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Adiponectin, one of the most ubiquitous adipokines found in the blood, plays a major role in glucolipid metabolism and energy metabolism and regulation. In recent years, a growing body of research indicates that adiponectin also plays a significant role in diabetic retinopathy. In the present review, we specifically address the protective effects of adiponectin on the development and progression of diabetic retinopathy through improvement in insulin resistance, alleviation of oxidative stress, limiting of inflammation, and prevention of vascular remodeling, with the aim to explore new potential approaches and targets for the prevention and treatment of diabetic retinopathy.
Hui Deng, Meichen Ai, and Yuchen Cao have contributed equally to this review.
Key Summary Points
The primary aim of diabetic retinopathy (DR) treatment is to address advanced organic changes, but attention should be paid to early inflammation. Controlling early inflammation may prevent the onset of DR, while decreasing long-term low-grade inflammation may delay the progress of DR.
Adiponectin (APN) has been found to have a protective effect on inflammation; thus the aim of this review is to explore the role of APN in DR in detail.
APN improves insulin resistance, oxidative stress, and apoptosis.
APN has anti-inflammatory properties and improves vascular dysfunction.
APN is a potential DR-targeted therapeutic site and predictive marker for DR.
Introduction
One of the most prevalent microvascular complications of diabetes is diabetic retinopathy (DR) [1]. Long-term chronic hyperglycemia in diabetic patients contributes to abnormal intracellular metabolism, degenerative pericyte degeneration, blood circulation disturbances, retinal ischemia, hypoxia and, ultimately, the onset of proliferative retinopathy. There are many risk factors for DR, including genetic predisposition, duration of diabetes, aberrant lipid metabolism, pregnancy, puberty, high blood pressure [2], hemoglobin A1c (HbA1c), nephropathy, serum creatinine, insulin treatment, and diabetic lower extremity arterial disease (DLEAD) [3]. Researchers typically use the International Clinical Diabetic Retinopathy Disease Severity Scale to classify DR severity into three main categories: no diabetic retinopathy (NDR), mild/moderate/severe non-proliferative diabetic retinopathy (NPDR), and proliferative diabetic retinopathy (PDR).
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It was originally assumed that adipose tissue served only as a storage site for energy. The discovery that cytokines are secreted by adipocytes (adipokines) has led to the classification of adipose tissue as an endocrine organ [4]. Adiponectin (APN), one of the most abundant adipokines in the blood [5], is synthesized and expressed in myoblasts [6], osteoblasts [7], epithelial cells [8], hepatic parenchymal cells [9], the brain [10], and the eye [11]. It regulates glucolipid and energy metabolism via adiponectin receptors 1 (AdipoR1) and 2 (AdipoR2) [12]. Extensive research has been conducted on the relationship between plasma APN levels and various metabolic diseases, such as type 2 diabetes mellitus (T2DM) [13, 14], atherosclerosis, inflammation, obesity, insulin resistance [15], cardiovascular disease [16, 17], and many others. Few studies, however, have concentrated on the causes of the association between plasma APN levels and DR, the impact of APN on DR, and the role APN plays in the pathogenesis of DR. There is also a lack of consistency in the research that is currently available on the correlation between circulating APN levels and DR and its various pathological stages [18‐20]. It is therefore crucial to distinguish whether APN plays a causal role in DR, whether it is a marker of the underlying mechanism of DR, and what impact it has on the eye under the diverse pathological conditions of DR. Concomitantly, the treatment of DR still involves major issues and challenges.
In this review, we search the PubMed database using the keywords “adiponectin” and “diabetic retinopathy” to identify pertinent publications in PubMed up to December 2022, and found a total of 88 articles related to our interests. After carefully reading the research articles, we looked at the structure and physiological function of APN to summarize the development of research on APN in DR and to better understand the role of APN, with the aim to generate new ideas for pharmacological intervention, treatment, and prevention of DR.
This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.
Adiponectin
Structure
In 1995, a 30-kDa adipocyte complement-associated protein (Acrp30), also known as APN, was identified as a novel adipocytokine that is exclusively produced by adipocytes [21]. Subsequent research revealed APN to be a protein encoded by the ADIPOQ gene (Adipose Most Abundant Gene Transcript 1 [APM1]) [22]. Its N- and C-termini of APN both contain a globular area, and the protein is structurally a member of the complement 1q (C1q) protein family. The collagen structural domain regulates APN multimerization, and disulfide bonds hold the APN oligomers together, which can structures ranging from trimers and hexamers to high-molecular-weight multimers [23‐25]. Nearly all APN present in plasma appear to be full-length APN, but earlier research detected small amounts of globular APN (gAPN) in human plasma [26], possibly resulting from cleavage of APN by leukocyte elastase secreted by activated monocytes and/or neutrophils [27].
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Physiological Function
Mainly through the actions of AdipoR1 and AdipoR2 on muscle and liver, APN is involved in the regulation of glucose, lipid, and energy metabolism as well as having anti-inflammatory effects [12]. Administration of recombinant APN in mice increases glucose uptake and increases lipid oxidation in muscle, reduces fatty acid uptake and hepatic gluconeogenesis in the liver, enhances insulin sensitivity [26, 28] and glucose tolerance [29], improves systemic insulin resistance [30], and may increase free fatty acid oxidation in muscle [26, 31]. This insulin-sensitizing effect of APN appears to be mediated, at least in part, via activation of AMP-activated protein kinase (AMPK) [32‐34]and through peroxisome proliferator-activated receptors (PPARs) [35, 36] to promote fatty acid oxidation [37]. Dysregulation of APN is therefore thought to be related with diseases associated with metabolic X syndrome, such as insulin resistance [38], obesity [39], T2DM [40], and cardiovascular disease [41]. Additionally, AdipoR1 and AdipoR2 are progestin and adipoQ (PAQ) receptors and may work to improve ceramidase activity, lower serum ceramide levels, and increase sphingosine-1-phosphate (S1P) levels, which shield cardiomyocytes and shield pancreatic-cells from apoptosis. Additionally, AdipoR1 and AdipoR2 are PAQ receptors and may work to improve ceramidase activity, lower serum ceramide levels, and increase S1P levels, which protect cardiomyocytes and prevent pancreatic cells from apoptosis [42].
Diabetic Retinopathy
To date, the connection between APN and DR has not yet been conclusively established. APN levels in plasma and aqueous humor have been found to be significantly greater in patients with DR than in those without DR and to be positively linked with DR severity [43], albeit APN levels in serum [44] and vitreous humor [45] have been found to be significantly lower in patients with DR. It is interesting to note that certain studies [46‐48] did not discover a relationship between serum APN levels and DR. Furthermore, current evidence regarding how APN relates to various DR severity levels is conflicting. A meta-analysis reported that there was no difference in the APN level between patients with NPDR and those with PDR and that the APN level in patients with T2DM with DR was significantly higher than that in patients with NDR [20]. Although serum APN was also considerably greater in patients with T1DM with PDR than in those with NDR or simple retinopathy, there was no difference between the two [49]. Thus, the relationship between APN levels in the diabetic state and DR is complicated and ambiguous. These results may be influenced by various molecular patterns of APN, diverse types of diabetes, treatment-related confounding factors, diabetes diagnosis and recruitment criteria, sample size, ethnicity, age of subjects, intricate technical procedures, staging, duration and severity of DR, and other factors. The majority of research carried out to date is cross-sectional in nature, and there is currently no definitive causal association between APN and DR. More studies are required to confirm the link between serum, aqueous humor, and vitreous APN concentrations and DR and its severity, as well as whether there is any correlation between APN levels in these three separate microenvironments in the same DR patient.
It is unclear how DR and APN gene polymorphisms are related. The majority of research has found no significant correlation between DR and the polymorphisms of the APN gene, including G276T (rs1501299), 94 (T/G), T45G (rs2241766), C-11377G (rs266729), and A-4034C (rs822394) [50‐55], possibly suggesting that APN gene polymorphisms may not be an independent risk factor for DR. However, the C-11377G polymorphism may be a possible risk factor for the development of diabetes and may potentially modulate the influence of insulin therapy on the risk of DR, since patients with the APN C-11377G polymorphism who receive insulin therapy have been found to be more likely to develop DR [50]. APN levels may not be related to DR according to a previous study that used APN-related single nucleotide polymorphisms as instrumental factors and Mendelian randomization analysis to corroborate this result [18]. By contrast, Mendelian randomization was used in another investigation in which the authors drew the conclusion that genetic variability in ADIPOQ caused lower APN levels [56]. An independent risk factor for DR has been shown to be the frequency of the G276T genotype, which is strongly and directly related to an elevated risk of developing DR in patients with DR [53]. Significant correlations exist between the T45G polymorphism and T2DM and DR. The ADIPOQ TT genotype is associated with a higher risk of T2DM and DR, with the ADIPOQ +45T/G and tumor necrosis factor-alpha (TNF-α) gene —308G/A polymorphisms together raising the risk of T2DM by 1.45-fold [57]. Patients heterozygous for the +45T → G (Gly15Gly) polymorphism have a decreased prevalence of DR, and the APN Tyr111His (T → C) polymorphism alters APN serum levels [58]. Further study is required to determine whether there is a specific association between DR and genetic susceptibility to APN, as well as whether there is an interaction with other risk factors.
APN Improves Insulin Resistance, Oxidative Stress, and Apoptosis
In diabetes patients, APN regulates glucolipid homeostasis and improves insulin resistance. In T2DM, hypoadiponectinemia boosts the levels of plasma glucose by limiting fatty acid oxidation, ramping up free fatty acids, slowing glucose absorption by skeletal muscle cells, and promoting gluconeogenesis in hepatic cells [59]. By encouraging lipid oxidative expansion and benign storage, APN improves the lipid profile. Additionally, it prevents inflammation, fibrosis, and steatosis while maintaining functional β cells to promote glucose homeostasis [60]. Furthermore, by binding to AdipoR1 and AdipoR2, APN increases ceramidase activity, resulting in increased ceramide catabolism and formation of its anti-apoptotic metabolite, S1P, which counteracts apoptosis in pancreatic β cells, improves hepatocyte insulin sensitivity [61], and promotes glycogen synthesis in skeletal muscle in T2DM [62]. Importantly, APN may also improve insulin resistance via the AMPK pathway by improving the catabolic state of the branched-chain amino acids (BCAAs) in the diabetic state (BCAAs are closely associated with insulin resistance) [63].
In hyperglycemic human microvascular retinal endothelial cells (HMRECs), APN was found to dramatically decrease the rate of reactive oxidative stress (ROS) and reactive nitrogen species (RNS) formation, elevate the expression of the antioxidant enzyme superoxide dismutase 2 (SOD2), and improve oxidative stress and apoptosis rates [64]. In one study, the level of oxidative stress-responsive apoptosis-inducing protein ORAIP, which acts as a pro-apoptotic ligand to promote apoptosis and damage the retina, was considerably higher in the vitreous humor of patients with PDR than in controls when exposed to oxidative stress. Oxidative stress downregulates microRNA (miRNA) levels, which encourages vascular endothelial growth factor (VEGF) expression and aids the progression of DR [65]. APN is associated with increased overall antioxidant status and decreased oxidative load cells [66]. Low APN concentration is significantly associated with elevated superoxide anion produced by NADPH oxidase in human artery wall arteries in T2DM [56]. Meanwhile, APN elevates nitric oxide (NO) bioavailability and lowers oxidative stress in the aorta via activating the AMPK/eNOS and cAMP/PKA signaling pathways [67]. By enhancing the PI3K/AKT/mTOR pathway, APN may inhibit rhesus choroid endothelial (RF-6A) cell autophagy [68]. However, more research is required to determine whether the aforementioned routes exist in the retinal microvasculature.
One study identified ceramide as a key factor in TOLL-like receptor 4-mediated insulin antagonism, and the anti-inflammatory effects of APN may be directly related to ceramide depletion [61]. Ceramide intracellular accumulation contributes to the development of diabetic microvascular complications through lipotoxic mechanisms, such as cell death, oxidative stress, and inflammation [69]. T-calmodulin mediates the function of APN in promoting exosome biogenesis and secretion, which can promote ceramide efflux and reduce cytosolic ceramide content in cultured endothelial cells and serve as a preventative measure against vascular injury [70] (Fig. 1).
Fig. 1
Schematic showing the production of adiponectin (APN), how it interacts with different microstructures, cells, tissues, and organs, and the different biological tasks it affects. DR Diabetic retinopathy, RNS reactive nitrogen species, ROS reactive oxygen species
APN has Anti-Inflammatory Properties and Improves Vascular Dysfunction
The concentrations of several intraocular cytokines in the aqueous humor and serum APN are well correlated [71]. APN levels in the brain and aqueous humor are significantly lower than those in the blood, pointing to a possible role for the blood–brain barrier and blood-retinal barrier (BRB) in maintaining APN homeostasis. AdipoR1 actively transports APN into the retina through the BRB, or via BRB catabolism, or it may be stimulated in DR to express endogenous or local APN [11, 47, 72].
APN can stabilize the BRB by inhibiting the increase in inflammatory factors, thereby ultimately delaying the DR process. Inflammation is inextricably linked to the development of DR: individuals with DR have considerably higher levels of inflammatory biomarkers than those without DR in their serum, aqueous humor, vitreous humor, and retina [45, 73‐76]. Diabetic rat models were found to have significantly higher levels of vitreous APN, TNF-α, interferon-gamma (INF-γ), matrix metalloproteinase (MMP)-2, and MMP-9 than the controls [77]. There is evidence that every unit increase in TNF-α level in T2DM increases the risk of retinopathy by 4085-fold [48]. Inflammatory cytokines, such as IFN-γ and TNF-α, increase VEGF-A and -C secretion in retinal pigment epithelium (RPE) cells and choroidal fibroblasts. VEGF-A causes BRB disruption and increases vascular permeability, activates a number of molecules that activate the kallikrein-kinin System (KKS) pathway, produces significant amounts of bradykinin binding to bradykinin receptor 1 (inflammatory response) and bradykinin receptor 2 (retinal vasodilatation) in the retina, promotes aggregation of neutrophils and microglia, and may increase vascular permeability and vascular edema, affecting inflammatory and angiogenic functions [45, 65]. BRB disruption results in cellular hypoxia, increased expression of hypoxia-inducible factor 1 (HIF-1), basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF), and oxygen-regulated protein 150 (ORP150), increased transcriptional translation of VEGF genes, binding of VEGF to ORP150 at the endoplasmic reticulum, secretion of cells to bind to the VEGF receptor (VEGFR) in target cells, and activation of downstream PI3K. Through the FAK pathway, VEGFR also activates paxillin, which causes cytoskeletal reorganization and cell migration [65]. The bioavailability of PDGF, FGF, and epidermal growth factor can all be decreased by the formation of complexes with APN [78]. APN inhibits TNF-α-induced activation of IKB-NF-κB (inhibitor of κB-nuclear factor kappa B) signaling via the cAMP pathway, decreases vascular cell adhesion molecule 1 (VCAM-1), prevents retinal leukocytes from adhering to vessel walls with inflammatory lesions, and inhibits endothelial cell migration and engraftment. These actions prevent BRB breakdown [70] and the development of pathological microvessels in the retina [79]. APN may inhibit myelomonocyte proliferation, phagocytic activity, and macrophage production of inflammatory mediators such as TNF-α [80]. The lack of APN-dependent anti-inflammatory and anti-MMP actions may hasten the degradation of retinal Claudin-5 and significantly enhance vascular permeability [70].
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By preventing a high glucose-induced reduction in cell viability, cell migration, and tube formation, APN interferes with retinal angiogenesis [68]. Inhibition of basal tube formation and blood vessel migration by APN expression in human umbilical vein macrovascular endothelial cells (HUVEC) and human retinal microvascular endothelial cells (hREC) is consistent with the action of intravitreal bevacizumab (IVB). APN is able to suppress retinal neovascularization by limiting the migration and proliferation of recombinant VEGF and PDR vitreous-induced hREC, as well as by inhibiting the proliferation and phosphorylation of ERK1/2 in recombinant VEGF-induced hREC [81]. APN upregulates the expression of the AdipoR1 and AdipoR2 genes, downregulates the expression of the TNF-α, interleukin-8 (IL-8), and interleukin-1beta (IL-1β) inflammatory proteins, adhesion molecules Intercellular adhesion molecule-1 (ICAM-1) and E-selectin, improves barrier dysfunction in hyperglycemic cells, inhibits leucocyte and endothelial cell migration, and improves basal tube formation. During hyperglycemia, APN enhances barrier function and decreases retinal endothelial cell permeability, consequently reducing inflammation and promoting angiogenesis. Molecular mechanisms of APN may directly affect inflammatory HMRECs and leukocytes, inhibit ROS, induce apoptosis, suppress NF-κB inflammatory signaling pathways, and downregulate TNF-α-mediated inflammatory responses. APN lessens the hyperglycemic effects of HMRECs by inhibiting endothelial cell adhesion and modulating extracellular matrix organization while improving barrier function (Fig. 2) [64].
Fig. 2
Schematic of the pathological manifestations of proliferative DR. The major characteristics of proliferative DR (PDR) include an inflammatory response, retinal vascular leakage, and retinal neovascularization. Through anti-inflammatory effects, blood–retinal barrier stabilization, and anti-neovascularization properties, APN can suppress the onset and progression of DR. IL Interleukin, INF interferon, MMP matrix metalloproteinase, PDGF platelet-derived growth factor, VEGF vascular endothelial growth factor
APN is thought to be a regulator of vascular remodeling because of its pleiotropic effects on maintaining vascular integrity. Based on research on the human retinal pigment epithelial cell line ARPE-19, which revealed a negative association between APN and VEGF levels [82], APN may play a preventative role in disorders associated with angiogenesis. APN is a crucial modulator of pathological neovascularization and inflammation [83]. Endothelial dysfunction resulting in poor endothelial cell repair and neovascularization are the primary symptoms of DR. Endothelial cell destruction, blood vessel loss, an increase in ROS production, an increase in inflammatory cells and cytokines, leukocyte leakage, and an increase in vascular leakage are all caused by hyperglycemia. Subsequent cellular hypoxia and ischemia will result in compensatory neovascularization.
APN can slow down or even inhibit the development of DR by improving hemodynamics. APN activates AMPK activity-dependent guanylyl cyclase, which in turn activates eNOS, causing NO production by endothelial cells, regulating vascular diameter, altering blood flow, and causing diastole of small porcine retinal arteries in vitro [84]. In men with T2DM and no or mild NPDR, circulating APN levels have been found to be positively linked with retinal blood flow. Retinal blood flow and APN concentrations are raised by increased blood flow velocity, expanded blood tube diameter, and decreased resistance [85]. In the early stages of DR, blood flow is reduced. It is possible that early use of APN may be able to prevent or even suppress the development of DR by increasing blood flow and delaying the onset of hypoxia.
APN as a Possible DR-Targeted Therapeutic Site and Predictive Marker for DR
Laser photocoagulation, vitreous injection of anti-VEGF medication, and vitreous surgery are currently used to treat DR. Lasers, however, can harm retinal cells permanently since they are destructive. There are also many shortcomings in the use of anti-VEGF drugs, including long-term resistance, high treatment costs, potential risk of retinal detachment due to intraocular injections, unresponsiveness in some patients, and poor patient compliance [86, 87]. It is urgently necessary to find a safe and effective target with minimal side effects in terms of treating DR and enhancing patient quality of life (Table 1).
CTRP9 protects against DR primarily by preventing the production of molecules linked to inflammation and maintaining the integrity of the BRB and tight junction proteins
APN has the potential to effectively treat retinal neovascularization because it may reduce VEGF and PDR vitreous-mediated endothelial cell proliferation, migration, and tube formation
The absence of ADIPOR1 drives retinal degeneration and elevated levels and abnormal spatial distribution of IRBP, which postulates a role for ADIPOR1 in retinol-like metabolism
APN may become a target therapeutic site for DR in the future. Leukemia inhibitory factor-human umbilical cord mesenchymal stem cells (LIF-hUCMSCs) protect the retina of diabetic rats by upregulating APN and neurotrophin-4 (NT-4) expression and downregulating high-sensitivity C-reactive protein (hs-CRP) expression in the retina [88]. Recombinant adeno-associated virus-adiponectin (rAAV2/1-ACrp30) downregulates NF-κBp65 and IκBα expression to improve impaired glucolipid metabolism, diabetes and its liver disease in diabetic rats, inhibits TNF-α secretion by macrophages, induces IκB degradation, blocks NF-κB activation, and reduces inflammatory responses. Clinical trials for recombinant APN therapy are not yet underway, however APN is a promising therapeutic target for the prevention and treatment of T2DM and its complications [89]. Higher concentrations of APN do not induce cytotoxicity in human endothelial cells and can be safely used as a therapeutic anti-angiogenic target for retinal angiogenesis. APN, which has anti-angiogenic, anti-proliferative, and anti-migratory activities, may be a possible therapeutic target for the therapy of posterior segment angiogenic processes (PDR and choroidal neovascular) in the eye. APN can be used in conjunction with IVB for the treatment of ocular angiogenesis based on the results of in vitro experiments demonstrating that APN and IVB have a comparable ability to inhibit tube formation and that the combination of APN and IVB significantly prevents the formation of VEGF and PDR vitreous-induced tubes in HUVEC [81]. IVB has also been linked to cases of herpetic epithelial keratitis that turned into meta-herpetic ulcers [90]. APN may be utilized in the future to treat patients who have not responded to IVB treatment or even as an alternative to IVB treatment. More research might be done in the meantime to show whether the combination of APN and IVB protects DR more effectively and safely than APN alone and whether the combination could lessen some of the negative effects of IVB. In contrast, other research suggests that the anti-APN antibody may be able to improve retinal edema and ischemia by decreasing the expression of VEGF-related factors and tight junction-related proteins in the retina. Retinal neovascularization was also reduced [86]. These various results could be the outcome of different experimental models, treatments, and observation periods. One study showed that higher levels of physical activity were associated with a lower incidence of glycoplasia [91] and that better behavioral tests and electroretinogram (ERG) results were obtained after exercise in a glucose rat model [92, 93]. Therefore, the authors hypothesized that exercise may have its protective effect on the eye by modulating the expression of APN and AdipoR in the plasma and retinal regions [94], pending further studies.
APN may have varied effects on the retina depending on the stage of DR, providing protection in the early stages and causing fibrosis in the later stages by inhibiting blood vessels. In one study, an increase in APN among various inflammatory molecules associated with retinal fibrosis in patients with proliferative vitreoretinopathy (PVR) and in patients with PDR led the authors to hypothesize that APN may regulate the switch to vascular fibrosis and drive the formation of fibrovascular membranes in the late stages of PVR and PDR, promoting the progression of retinal fibrosis [95]. According to these authors, APN may be a candidate for treating angiogenesis early on in PDR and promoting posterior segment fibrosis at a later stage. Additionally, novel therapeutic modalities may be created to specifically target APN for the treatment of posterior segment fibrosis in vitreoretinal disease [95].
The APN receptor (APNR), certain drugs, and APN homologs may have beneficial effects on DR. APN and its receptors are expressed in the murine neural retina and RPE choroid. Orthox endothelium angiogenic cells are activated by APN-AdipoR1-AMPK to protect and repair endothelial damage. APN-AdipoR2-PPARα inhibits inflammation and oxidative stress-induced insulin resistance [11]. Animals with knockouts of ADIPOR1 display early visual system abnormalities that ultimately result in retinal degeneration, elevated interphotoreceptor retinoid-binding protein (IRBP) levels, and spatial distribution anomalies. As a result, it is possible that APNR1 functions independently of APN and contributes more to visual biology than glucose metabolism [96]. In muscle and liver, AdipoRon had very similar effects to APN. Oral AdipoR agonists are a promising treatment for T2DM, even if only APN shows the most benefits, including reducing insulin resistance and impaired glucose tolerance and lengthening the shorter life expectancy of patients on a high-fat diet [37]. Some medications may protect against DR via the APN pathway. Through APN-mediated regulation of TNF-α, thiazolidinediones (TZDs) reduce pathological retinal microangiogenesis in ischemic retinal disease [97]. The fibroblast growth factor 21 (FGF21)-APN-ceramide axis regulates energy expenditure and insulin action in mice. FGF21 is heavily reliant on APN and can rapidly and potently stimulate APN secretion while reducing ceramide accumulation in obese animals [98], improving the lipid profile and insulin resistance, and preventing kidney damage [99]. However, it has also been suggested that FGF21 prevents early DR independently of downstream APN [100]. FGF21/APN can be used as a biomarker of glycemic deterioration and a stand-alone predictor of prodromal diabetes and diabetes mellitus since its level increases gradually with decreasing glycemic control in T2DM [101]. A long-acting FGF21 analog (PF-05231023) with protective effects on DR in streptozotocin-induced diabetic mice was shown to restore retinal function and photoreceptor cell morphology, inhibit oxidative stress-induced photoreceptor cell inflammation, and reduce retinal inflammation [100]. The closest paralog to APN is an adipocytokine called C1q/TNF-related protein-9 (CTRP9) [102], which plays a beneficial role in glucose metabolism and vascular protection, lowering blood glucose in diabetic mice [103]. CTRP9 inhibits the expression of IL-1β, TNF-α, monocyte chemoattractant protein-1 (MCP-1), and adhesion molecules in the retina of db/db mice, inhibits the activation of NF-κB, balances the expression of pigment epithelium-derived factor (PEDF) and VEGF, and downregulates tight junction protein, thereby inhibiting the breakdown of BRB and alleviating early vascular leakage in the diabetic retina, and ultimately achieving protection against DR [104]. It may be that in the future, APNR, drugs that protect against DR via the APN pathway, and the relationship between homologs of APN and DR and the specific mechanisms can be used in conjunction with APN to diagnose DR and co-administer drugs, among other possibilities.
APN may be a potential marker in the future as a target therapeutic site for DR and as a predictor of DR. APN may be utilized as a predictor and marker of T2DM and its prognostic analysis [105], and as a predictor and marker for complications in type 1 diabetes mellitus [106]. Serum APN correlates with intraocular cytokine (including VEGF) concentrations in atrial fluid and can be used as a clinical predictive marker for intraocular inflammation associated with aqueous humor APN, aqueous humor VEGF, and serum VEGF [71].
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Discussion
The results of the studies mentioned in the preceding sections suggest that APN may have a protective effect on the retina by reducing insulin resistance, oxidative stress, apoptosis, inflammation, and endothelial dysfunction. Nevertheless, the relevance of APN and its genetic polymorphisms to DR and of the upstream and downstream pathways involved is not particularly clear. In addition, although there is a lack of high-quality evidence on the therapeutic effect of APN in diabetes and DR, many results to date support our view that APN may have a protective function and be a potential therapeutic target, and we will be conducting rigorous trials to obtain evidence to support this perspective in the future. In conclusion, this review suggests that APN is likely to be a new therapeutic target and a predictive marker for DR, but additional basic and clinical research is required to further elucidate its mechanisms. Animal models of diabetes are crucial for the study of DR, but there is currently no single model that accurately represents how DR develops in humans. Although rodent models only exhibit early signs of DR and higher-order animals have relatively advanced retinopathy, neither of these models simulate late stages of human DR. Long-term hyperglycemia does not stimulate the development of neovascularization in animals overexpressing VEGF, and rodents undergoing hypoxic excitation induce regression of neovascularization [107]. Therefore, the choice of an appropriate animal model needs to take into account both the advantages and limitations of that model, and better animal models need to be investigated.
Diabetic macular edema (DME) can occur at any stage of DR. The neuroretina's aberrant thickening due to fluid accumulation, frequently accompanied by macular cystoid edema, is the most common cause of vision loss in patients with DR [108]. Intravitreal injections of corticosteroids and anti-VEGF medications are effective treatments for DME [109]. One study showed that bevacizumab reduced VEGF and APN concentrations in patients with T2DM, with a corresponding improvement in visual function and no ocular or systemic side effects [110]. A promising strategy for future research is examination of the possible contribution of APN to improve DME. It has been suggested that in patients with gestational diabetes mellitus (GDM), TNF-α and leptin circulating levels are increased and APN levels are decreased [111], and that hypolipoproteinemia may play an important role in the development of GDM [112]. Serum APN level in early pregnancy may be a strong predictor of GDM [113] with moderate predictive accuracy [114], and the serum Ficolin-3/APN ratio may also be a predictor of GDM [115]. Gestational diabetes can worsen DR in pregnant patients with pre-existing diabetes [116], but it does not raise the risk of DR during pregnancy. To our knowledge, there are no studies that correlate APN with GDM retinopathy and associated mechanisms. Future studies could investigate whether APN can predict gestational diabetic retinopathy, whether it can be graded for severity, and whether it can be used as a therapeutic target for GDM.
In addition to DR, a number of other ophthalmic diseases, including retinal degeneration of prematurity (ROP) [117], age-related macular degeneration (AMD) [95], and hypertensive retinopathy (HR) [118], may be inextricably linked to reduced levels of APN. APN and its related compounds play a protective role in ROP, AMD, and HR. However, the regulatory mechanisms are still unclear [10]. As a result, research into disease and APN processes is crucial since it could lead to future forecasts for these diseases as well as therapeutic and innovative drug development regarding this target. There is currently a developing corpus of study on omega-3 long-chain polyunsaturated fatty acid (LCPUFA) [119, 120], whose protective mechanisms in ROP and AMD [121] are strongly related to APN. Patients with HR may benefit from the therapeutic strategy of consuming more omega-3 LCPUFA to promote APN production since APN can lower blood pressure by encouraging endothelium-dependent vasodilation [122]. Therefore, future research could focus on the protective benefits of omega-3 LCPUFA and its related medicines on ROP, AMD, and HR, as well as their prospective uses and the mechanisms and roles of APN activity in them.
Acknowledgements
Funding
No funding or sponsorship was received for this study, and the journal’s Rapid Service fee was funded by the authors.
Author Contributions
All of the authors contributed to the conception of the review. Hui Deng, Meichen Ai, and Yuchen Cao conceived the study and made substantive revisions to the important content of the manuscript. These authors are also the major contributors to the writing of the manuscript. Liyang Cai, Xi Guo, and Xiongyi Yang provided suggestions and technical support, revised important sections of the manuscript, and assisted in the literature search. Guoguo Yi and Min Fu critically reviewed the manuscript. All of the authors read and approved the final manuscript.
Disclosures
Hui Deng, Meichen Ai, Yuchen Cao, Liyang Cai, Xi Guo, Xiongyi Yang, Guoguo Yi, and Min Fu have nothing to disclose.
Compliance with Ethics Guidelines
This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.
Data Availability
Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.
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Cheung N, Mitchell P, Wong TY. Diabetic retinopathy. Lancet. 2010;376(9735):124–36.PubMedCrossRef
2.
Moreno A, Lozano M, Salinas P. Diabetic retinopathy. Nutr Hosp. 2013;28(Suppl 2):53–6.PubMed
3.
Li W, Song Y, Chen K, et al. Predictive model and risk analysis for diabetic retinopathy using machine learning: a retrospective cohort study in China. BMJ Open. 2021;11(11):e050989.PubMedPubMedCentralCrossRef
4.
Lyzogubov VV, Tytarenko RG, Thotakura S, Viswanathan T, Bora NS, Bora PS. Inhibition of new vessel growth in mouse model of laser-induced choroidal neovascularization by adiponectin peptide II. Cell Biol Int. 2009;33(7):765–71.PubMedPubMedCentralCrossRef
5.
Letra L, Rodrigues T, Matafome P, Santana I, Seiça R. Adiponectin and sporadic Alzheimer’s disease: clinical and molecular links. Front Neuroendocrinol. 2019;52:1–11.PubMedCrossRef
6.
Delaigle AM, Jonas JC, Bauche IB, Cornu O, Brichard SM. Induction of adiponectin in skeletal muscle by inflammatory cytokines: in vivo and in vitro studies. Endocrinology. 2004;145(12):5589–97.PubMedCrossRef
7.
Berner HS, Lyngstadaas SP, Spahr A, et al. Adiponectin and its receptors are expressed in bone-forming cells. Bone. 2004;35(4):842–9.PubMedCrossRef
8.
Patel S, Flyvbjerg A, Kozàkovà M, et al. Variation in the ADIPOQ gene promoter is associated with carotid intima media thickness independent of plasma adiponectin levels in healthy subjects. Eur Heart J. 2008;29(3):386–93.PubMedCrossRef
9.
Yoda-Murakami M, Taniguchi M, Takahashi K, et al. Change in expression of GBP28/adiponectin in carbon tetrachloride-administrated mouse liver. Biochem Biophys Res Commun. 2001;285(2):372–7.PubMedCrossRef
10.
Thundyil J, Pavlovski D, Sobey CG, Arumugam TV. Adiponectin receptor signalling in the brain. Br J Pharmacol. 2012;165(2):313–27.PubMedPubMedCentralCrossRef
11.
Lin T, Qiu Y, Liu Y, Mohan R, Li Q, Lei B. Expression of adiponectin and its receptors in type 1 diabetes mellitus in human and mouse retinas. Mol Vis. 2013;19:1769–78.PubMedPubMedCentral
12.
Kaarniranta K, Paananen J, Nevalainen T, et al. Adiponectin receptor 1 gene (ADIPOR1) variant is associated with advanced age-related macular degeneration in Finnish population. Neurosci Lett. 2012;513(2):233–7.PubMedCrossRef
13.
Nielsen MB, Çolak Y, Benn M, Nordestgaard BG. Low plasma adiponectin in risk of type 2 diabetes: observational analysis and one- and two-sample mendelian randomization analyses in 756,219 individuals. Diabetes. 2021;70(11):2694–705.PubMedCrossRef
14.
Lian K, Guo X, Huang Q, et al. Reduction levels and the effects of high-molecular-weight adiponectin via AMPK/eNOS in chinese type 2 diabetes. Exp Clin Endocrinol Diabetes. 2016;124(9):541–7.PubMedCrossRef
Ebrahimi-Mamaeghani M, Mohammadi S, Arefhosseini SR, Fallah P, Bazi Z. Adiponectin as a potential biomarker of vascular disease. Vasc Health Risk Manag. 2015;11:55–70.PubMedPubMedCentral
17.
Villarreal-Molina MT, Antuna-Puente B. Adiponectin: anti-inflammatory and cardioprotective effects. Biochimie. 2012;94(10):2143–9.PubMedCrossRef
18.
Huang YC, Chang YW, Cheng CW, Wu CM, Liao WL, Tsai FJ. Causal relationship between adiponectin and diabetic retinopathy: a Mendelian randomization study in an Asian population. Genes (Basel). 2020;12(1):17.PubMedPubMedCentralCrossRef
19.
Fan X, Wu Q, Li Y, et al. Association between adiponectin concentrations and diabetic retinopathy in patients with type 2 diabetes: a meta analysis. Chin Med J. 2014;127(4):765–71.PubMed
20.
Rodríguez AJ, Nunes VS, Mastronardi CA, Neeman T, Paz-Filho GJ. Association between circulating adipocytokine concentrations and microvascular complications in patients with type 2 diabetes mellitus: a systematic review and meta-analysis of controlled cross-sectional studies. J Diabetes Complic. 2016;30(2):357–67.CrossRef
21.
Scherer PE, Williams S, Fogliano M, Baldini G, Lodish HF. A novel serum protein similar to C1q, produced exclusively in adipocytes. J Biol Chem. 1995;270(45):26746–9.PubMedCrossRef
22.
Mtiraoui N, Ezzidi I, Turki A, Chaieb A, Mahjoub T, Almawi WY. Single-nucleotide polymorphisms and haplotypes in the adiponectin gene contribute to the genetic risk for type 2 diabetes in Tunisian Arabs. Diabetes Res Clin Pract. 2012;97(2):290–7.PubMedCrossRef
23.
Waki H, Yamauchi T, Kamon J, et al. Impaired multimerization of human adiponectin mutants associated with diabetes. Molecular structure and multimer formation of adiponectin. J Biol Chem. 2003;278(41):40352–63.PubMedCrossRef
24.
Tsao TS, Tomas E, Murrey HE, et al. Role of disulfide bonds in Acrp30/adiponectin structure and signaling specificity. Different oligomers activate different signal transduction pathways. J Biol Chem. 2003;278(50):50810–7.PubMedCrossRef
25.
Kadowaki T, Yamauchi T. Adiponectin and adiponectin receptors. Endocr Rev. 2005;26(3):439–51.PubMedCrossRef
26.
Fruebis J, Tsao TS, Javorschi S, et al. Proteolytic cleavage product of 30-kDa adipocyte complement-related protein increases fatty acid oxidation in muscle and causes weight loss in mice. Proc Natl Acad Sci USA. 2001;98(4):2005–10.PubMedPubMedCentralCrossRef
27.
Waki H, Yamauchi T, Kamon J, et al. Generation of globular fragment of adiponectin by leukocyte elastase secreted by monocytic cell line THP-1. Endocrinology. 2005;146(2):790–6.PubMedCrossRef
28.
Yamauchi T, Kamon J, Waki H, et al. The fat-derived hormone adiponectin reverses insulin resistance associated with both lipoatrophy and obesity. Nat Med. 2001;7(8):941–6.PubMedCrossRef
29.
Berg AH, Combs TP, Du X, Brownlee M, Scherer PE. The adipocyte-secreted protein Acrp30 enhances hepatic insulin action. Nat Med. 2001;7(8):947–53.PubMedCrossRef
30.
Heilbronn LK, Smith SR, Ravussin E. The insulin-sensitizing role of the fat derived hormone adiponectin. Curr Pharm Des. 2003;9(17):1411–8.PubMedCrossRef
31.
Wolf G. Adiponectin: a regulator of energy homeostasis. Nutr Rev. 2003;61(8):290–2.PubMedCrossRef
32.
Yamauchi T, Kamon J, Minokoshi Y, et al. Adiponectin stimulates glucose utilization and fatty-acid oxidation by activating AMP-activated protein kinase. Nat Med. 2002;8(11):1288–95.PubMedCrossRef
33.
Tomas E, Tsao TS, Saha AK, et al. Enhanced muscle fat oxidation and glucose transport by ACRP30 globular domain: acetyl-CoA carboxylase inhibition and AMP-activated protein kinase activation. Proc Natl Acad Sci USA. 2002;99(25):16309–13.PubMedPubMedCentralCrossRef
34.
Kahn BB, Alquier T, Carling D, Hardie DG. AMP-activated protein kinase: ancient energy gauge provides clues to modern understanding of metabolism. Cell Metab. 2005;1(1):15–25.PubMedCrossRef
35.
Kersten S, Desvergne B, Wahli W. Roles of PPARs in health and disease. Nature. 2000;405(6785):421–4.PubMedCrossRef
36.
Yamauchi T, Kamon J, Waki H, et al. Globular adiponectin protected ob/ob mice from diabetes and ApoE-deficient mice from atherosclerosis. J Biol Chem. 2003;278(4):2461–8.PubMedCrossRef
37.
Okada-Iwabu M, Yamauchi T, Iwabu M, et al. A small-molecule AdipoR agonist for type 2 diabetes and short life in obesity. Nature. 2013;503(7477):493–9.PubMedCrossRef
38.
Vasseur F, Leprêtre F, Lacquemant C, Froguel P. The genetics of adiponectin. Curr Diab Rep. 2003;3(2):151–8.PubMedCrossRef
39.
Hu E, Liang P, Spiegelman BM. AdipoQ is a novel adipose-specific gene dysregulated in obesity. J Biol Chem. 1996;271(18):10697–703.PubMedCrossRef
40.
Hotta K, Funahashi T, Arita Y, et al. Plasma concentrations of a novel, adipose-specific protein, adiponectin, in type 2 diabetic patients. Arterioscler Thromb Vasc Biol. 2000;20(6):1595–9.PubMedCrossRef
41.
Dzielińska Z, Januszewicz A, Wiecek A, et al. Decreased plasma concentration of a novel anti-inflammatory protein–adiponectin–in hypertensive men with coronary artery disease. Thromb Res. 2003;110(5–6):365–9.PubMedCrossRef
42.
Villa NY, Kupchak BR, Garitaonandia I, et al. Sphingolipids function as downstream effectors of a fungal PAQR. Mol Pharmacol. 2009;75(4):866–75.PubMedCrossRef
43.
Hadjadj S, Aubert R, Fumeron F, et al. Increased plasma adiponectin concentrations are associated with microangiopathy in type 1 diabetic subjects. Diabetologia. 2005;48(6):1088–92.PubMedCrossRef
44.
Yilmaz MI, Sonmez A, Acikel C, et al. Adiponectin may play a part in the pathogenesis of diabetic retinopathy. Eur J Endocrinol. 2004;151(1):135–40.PubMedCrossRef
45.
Ucgun NI, Zeki-Fikret C, Yildirim Z. Inflammation and diabetic retinopathy. Mol Vis. 2020;26:718–21.PubMedPubMedCentral
46.
Dossarps D, Petit JM, Guiu B, et al. Body fat distribution and adipokine secretion are not associated with diabetic retinopathy in patients with type 2 diabetes mellitus. Ophthalmic Res. 2014;51(1):42–5.PubMedCrossRef
47.
Mao D, Peng H, Li Q, et al. Aqueous humor and plasma adiponectin levels in proliferative diabetic retinopathy patients. Curr Eye Res. 2012;37(9):803–8.PubMedCrossRef
48.
Matsuda M, Kawasaki F, Yamada K, et al. Impact of adiposity and plasma adipocytokines on diabetic angiopathies in Japanese Type 2 diabetic subjects. Diabet Med. 2004;21(8):881–8.PubMedCrossRef
49.
Frystyk J, Tarnow L, Krarup Hansen T, Parving HH, Flyvbjerg A. Increased serum adiponectin levels in type 1 diabetic patients with microvascular complications. Diabetologia. 2005;48(9):1911–8.PubMedCrossRef
50.
Li Y, Wu QH, Jiao ML, et al. Gene-environment interaction between adiponectin gene polymorphisms and environmental factors on the risk of diabetic retinopathy. J Diabetes Investig. 2015;6(1):56–66.PubMedCrossRef
51.
Choe EY, Wang HJ, Kwon O, et al. Variants of the adiponectin gene and diabetic microvascular complications in patients with type 2 diabetes. Metabolism. 2013;62(5):677–85.PubMedCrossRef
52.
Rudofsky G Jr, Schlimme M, Schlotterer A, et al. No association of the 94T/G polymorphism in the adiponectin gene with diabetic complications. Diabetes Obes Metab. 2005;7(4):455–9.PubMedCrossRef
53.
Gouliopoulos N, Siasos G, Bouratzis N, et al. Polymorphism analysis of ADIPOQ gene in Greek patients with diabetic retinopathy. Ophthalmic Genet. 2022;43(3):326–31.PubMedCrossRef
54.
Yoshioka K, Yoshida T, Takakura Y, et al. Adiponectin gene polymorphism (G276T) and diabetic retinopathy in Japanese patients with Type 2 diabetes. Diabet Med. 2004;21(10):1158–9.PubMedCrossRef
55.
Aioanei CS, Ilies RF, Bala C, et al. The role of adiponectin and toll-like receptor 4 gene polymorphisms on non-proliferative retinopathy in type 2 diabetes mellitus patients. A case-control study in Romanian Caucasians patients. Acta Endocrinol (Buchar). 2019;5(1):32–8.PubMedCrossRef
56.
Antonopoulos AS, Margaritis M, Coutinho P, et al. Adiponectin as a link between type 2 diabetes and vascular NADPH oxidase activity in the human arterial wall: the regulatory role of perivascular adipose tissue. Diabetes. 2014;64(6):2207–19.PubMedCrossRef
57.
Sikka R, Raina P, Matharoo K, et al. TNF-α (g.−308 G > A) and ADIPOQ (g. + 45 T > G) gene polymorphisms in type 2 diabetes and microvascular complications in the region of Punjab (North–West India). Curr Eye Res. 2014;39(10):1042–51.PubMedCrossRef
58.
Zietz B, Buechler C, Kobuch K, Neumeier M, Schölmerich J, Schäffler A. Serum levels of adiponectin are associated with diabetic retinopathy and with adiponectin gene mutations in Caucasian patients with diabetes mellitus type 2. Exp Clin Endocrinol Diabetes. 2008;116(09):532–6.PubMedCrossRef
59.
Sheng T, Yang K. Adiponectin and its association with insulin resistance and type 2 diabetes. J Genet Genom. 2008;35(6):321–6.CrossRef
60.
Tao C, Sifuentes A, Holland WL. Regulation of glucose and lipid homeostasis by adiponectin: effects on hepatocytes, pancreatic β cells and adipocytes. Best Pract Res Clin Endocrinol Metab. 2014;28(1):43–58.PubMedCrossRef
61.
Holland WL, Miller RA, Wang ZV, et al. The pleiotropic actions of adiponectin are initiated via receptor-mediated activation of ceramidase activity. Nat Med. 2011;17(1):55–63.PubMedCrossRef
62.
Yokoyama H, Emoto M, Mori K, et al. Plasma adiponectin level is associated with insulin-stimulated nonoxidative glucose disposal. J Clin Endocrinol Metab. 2006;91(1):290–4.PubMedCrossRef
63.
Lian K, Du C, Liu Y, et al. Impaired adiponectin signaling contributes to disturbed catabolism of branched-chain amino acids in diabetic mice. Diabetes. 2014;64(1):49–59.PubMedCrossRef
64.
Bushra S, Al-Sadeq DW, Bari R, Sahara A, Fadel A, Rizk N. Adiponectin ameliorates hyperglycemia-induced retinal endothelial dysfunction, highlighting pathways, regulators, and networks. J Inflamm Res. 2022;15:3135–66.PubMedPubMedCentralCrossRef
65.
Xia HQ, Yang JR, Zhang KX, et al. Molecules related to diabetic retinopathy in the vitreous and involved pathways. Int J Ophthalmol. 2022;15(7):1180–9.PubMedPubMedCentralCrossRef
66.
Prior SL, Tang TS, Gill GV, Bain SC, Stephens JW. Adiponectin, total antioxidant status, and urine albumin excretion in the low-risk “Golden Years” type 1 diabetes mellitus cohort. Metabolism. 2011;60(2):173–9.PubMedCrossRef
67.
Wong WT, Tian XY, Xu A, et al. Adiponectin is required for PPARgamma-mediated improvement of endothelial function in diabetic mice. Cell Metab. 2011;14(1):104–15.PubMedCrossRef
68.
Li R, Du J, Yao Y, Yao G, Wang X. Adiponectin inhibits high glucose-induced angiogenesis via inhibiting autophagy in RF/6A cells. J Cell Physiol. 2019;234(11):20566–76.PubMedCrossRef
69.
Mandal N, Grambergs R, Mondal K, Basu SK, Tahia F, Dagogo-Jack S. Role of ceramides in the pathogenesis of diabetes mellitus and its complications. J Diabetes Complicat. 2021;35(2): 107734.CrossRef
70.
Sakaue TA, Fujishima Y, Fukushima Y, et al. Adiponectin accumulation in the retinal vascular endothelium and its possible role in preventing early diabetic microvascular damage. Sci Rep. 2022;12(1):4159.PubMedPubMedCentralCrossRef
71.
Yang HS, Choi YJ, Han HY, et al. Serum and aqueous humor adiponectin levels correlate with diabetic retinopathy development and progression. PLoS ONE. 2021;16(11): e0259683.PubMedPubMedCentralCrossRef
72.
Fu Z, Gong Y, Löfqvist C, Hellström A, Smith LE. Review: adiponectin in retinopathy. Biochim Biophys Acta. 2016;1862(8):1392–400.PubMedPubMedCentralCrossRef
73.
Mason RH, Minaker SA, Lahaie Luna G, et al. Changes in aqueous and vitreous inflammatory cytokine levels in proliferative diabetic retinopathy: a systematic review and meta-analysis. Eye (Lond). 2022.
74.
Slepova OS, Gerasimenko VL, Zakharova G, Novikova-Bilak TI. Comparative study of the role of cytokines in various eye diseases. 2. Diabetic retinopathy. Vestn Oftalmol. 2001;117(3):35–7.PubMed
75.
Johnsen-Soriano S, Sancho-Tello M, Arnal E, et al. IL-2 and IFN-gamma in the retina of diabetic rats. Graefes Arch Clin Exp Ophthalmol. 2010;248(7):985–90.PubMedCrossRef
76.
Cvitkovic K, Sesar A, Sesar I, et al. Concentrations of selected cytokines and vascular endothelial growth factor in aqueous humor and serum of diabetic patients. Semin Ophthalmol. 2020;35(2):126–33.PubMedCrossRef
77.
Özay Y, Ozek D, Yıldırım F, Yıldırım Z. The effect of diabetes on vitreous levels of adiponectin and inflammatory cytokines in experimental rat model. Adv Clin Exp Med. 2020;29(4):449–52.PubMedCrossRef
78.
Wang Y, Lam KSL, Xu JY, et al. Adiponectin inhibits cell proliferation by interacting with several growth factors in an oligomerization-dependent manner. J Biol Chem. 2005;280(18):18341–7.PubMedCrossRef
79.
Higuchi A, Ohashi K, Kihara S, Walsh K, Ouchi N. Adiponectin suppresses pathological microvessel formation in retina through modulation of tumor necrosis factor-alpha expression. Circ Res. 2009;104(9):1058–65.PubMedPubMedCentralCrossRef
80.
Ouchi N, Kihara S, Arita Y, et al. Adiponectin, an adipocyte-derived plasma protein, inhibits endothelial NF-κB signaling through a cAMP-dependent pathway. Circulation. 2000;102(11):1296–301.PubMedCrossRef
81.
Palanisamy K, Nareshkumar RN, Sivagurunathan S, Raman R, Sulochana KN, Chidambaram S. Anti-angiogenic effect of adiponectin in human primary microvascular and macrovascular endothelial cells. Microvasc Res. 2019;122:136–45.PubMedCrossRef
82.
Srinivasan V, Sulochana KN. Effect of adiponectin on expression of vascular endothelial growth factor and pigment epithelium-derived factor: an in vitro study. Indian J Pharmacol. 2015;47(1):117–20.PubMedPubMedCentralCrossRef
Omae T, Nagaoka T, Tanano I, Yoshida A. Adiponectin-induced dilation of isolated porcine retinal arterioles via production of nitric oxide from endothelial cells. Invest Ophthalmol Vis Sci. 2013;54(7):4586–94.PubMedCrossRef
85.
Omae T, Nagaoka T, Yoshida A. Relationship between retinal blood flow and serum adiponectin concentrations in patients with type 2 diabetes mellitus. Invest Ophthalmol Vis Sci. 2015;56(6):4143–9.PubMedCrossRef
86.
Nishinaka A, Nakamura S, Tanaka M, et al. Excess adiponectin in eyes with progressive ocular vascular diseases. FASEB J. 2021;35(2): e21313.PubMedCrossRef
87.
Wang W, Lo ACY. Diabetic retinopathy: pathophysiology and treatments. Int J Mol Sci. 2018;19(6):1816.PubMedPubMedCentralCrossRef
88.
Chen SN, Xu ZG, Ma YX, et al. Protective effect of LIF-huMSCs on the retina of diabetic model rats. Int J Ophthalmol. 2021;14(10):1508–17.PubMedPubMedCentralCrossRef
89.
Long W, Hui JuZ, Fan Z, Jing W, Qiong L. The effect of recombinant adeno-associated virus-adiponectin (rAAV2/1-Acrp30) on glycolipid dysmetabolism and liver morphology in diabetic rats. Gen Comp Endocrinol. 2014;206:1–7.PubMedCrossRef
90.
Behera G, Gokhale T, Deb AK, Babu KR. Meta-herpetic ulcer following intravitreal bevacizumab. Eur J Ophthalmol. 2022;32(1):np24–6.PubMedCrossRef
91.
Wang YX, Wei WB, Xu L, Jonas JB. Physical activity and eye diseases. The Beijing Eye Study. Acta Ophthalmol. 2019;97(3):325–31.PubMedCrossRef
92.
Allen RS, Hanif AM, Gogniat MA, et al. TrkB signalling pathway mediates the protective effects of exercise in the diabetic rat retina. Eur J Neurosci. 2018;47(10):1254–65.PubMedPubMedCentralCrossRef
93.
Kim DY, Jung SY, Kim CJ, Sung YH, Kim JD. Treadmill exercise ameliorates apoptotic cell death in the retinas of diabetic rats. Mol Med Rep. 2013;7(6):1745–50.PubMedCrossRef
94.
Li HY, Hong X, Cao QQ, So KF. Adiponectin, exercise and eye diseases. Int Rev Neurobiol. 2019;147:281–94.PubMedCrossRef
95.
Palanisamy K, Raman R, Sulochana KN, Chidambaram S. Adiponectin: a potential candidate for treating fibrosis in posterior segment of the eye. Med Hypotheses. 2019;123:9–12.PubMedCrossRef
96.
Sluch VM, Banks A, Li H, et al. ADIPOR1 is essential for vision and its RPE expression is lost in the Mfrp(rd6) mouse. Sci Rep. 2018;8(1):14339.PubMedPubMedCentralCrossRef
97.
Higuchi A, Ohashi K, Shibata R, Sono-Romanelli S, Walsh K, Ouchi N. Thiazolidinediones reduce pathological neovascularization in ischemic retina via an adiponectin-dependent mechanism. Arterioscler Thromb Vasc Biol. 2010;30(1):46–53.PubMedCrossRef
98.
Holland WL, Adams AC, Brozinick JT, et al. An FGF21-adiponectin-ceramide axis controls energy expenditure and insulin action in mice. Cell Metab. 2013;17(5):790–7.PubMedPubMedCentralCrossRef
99.
Kim HW, Lee JE, Cha JJ, et al. Fibroblast growth factor 21 improves insulin resistance and ameliorates renal injury in db/db mice. Endocrinology. 2013;154(9):3366–76.PubMedCrossRef
100.
Fu Z, Wang Z, Liu CH, et al. Fibroblast growth factor 21 protects photoreceptor function in type 1 diabetic mice. Diabetes. 2018;67(5):974–85.PubMedPubMedCentralCrossRef
101.
Liu D, Wu L, Gao Q, et al. FGF21/adiponectin ratio predicts deterioration in glycemia: a 4.6-year prospective study in China. Cardiovasc Diabetol. 2021;20(1):157.PubMedPubMedCentralCrossRef
102.
Kambara T, Shibata R, Ohashi K, et al. C1q/tumor necrosis factor-related protein 9 protects against acute myocardial injury through an adiponectin receptor I-AMPK-dependent mechanism. Mol Cell Biol. 2015;35(12):2173–85.PubMedPubMedCentralCrossRef
103.
Wong GW, Krawczyk SA, Kitidis-Mitrokostas C, et al. Identification and characterization of CTRP9, a novel secreted glycoprotein, from adipose tissue that reduces serum glucose in mice and forms heterotrimers with adiponectin. FASEB J. 2009;23(1):241–58.PubMedPubMedCentralCrossRef
104.
Li W, Ma N, Liu M-X, et al. C1q/TNF-related protein-9 attenuates retinal inflammation and protects blood–retinal barrier in db/db mice. Eur J Pharmacol. 2019;853:289–98.PubMedCrossRef
105.
Li S, Shin HJ, Ding EL, van Dam RM. Adiponectin levels and risk of type 2 diabetes: a systematic review and meta-analysis. JAMA. 2009;302(2):179–88.PubMedCrossRef
106.
Jung CH, Kim BY, Mok JO, Kang SK, Kim CH. Association between serum adipocytokine levels and microangiopathies in patients with type 2 diabetes mellitus. J Diabetes Investig. 2014;5(3):333–9.PubMedCrossRef
107.
Lai AK, Lo AC. Animal models of diabetic retinopathy: summary and comparison. J Diabetes Res. 2013;2013: 106594.PubMedPubMedCentralCrossRef
108.
Rübsam A, Parikh S, Fort PE. Role of inflammation in diabetic retinopathy. Int J Mol Sci. 2018;19(4):942.PubMedPubMedCentralCrossRef
109.
Ehlers JP, Yeh S, Maguire MG, et al. Intravitreal pharmacotherapies for diabetic macular edema: a report by the American academy of ophthalmology. Ophthalmology. 2022;129(1):88–99.PubMedCrossRef
110.
Costagliola C, Daniele A, dell’Omo R, et al. Aqueous humor levels of vascular endothelial growth factor and adiponectin in patients with type 2 diabetes before and after intravitreal bevacizumab injection. Exp Eye Res. 2013;110:50–4.PubMedCrossRef
111.
Xu J, Zhao YH, Chen YP, et al. Maternal circulating concentrations of tumor necrosis factor-alpha, leptin, and adiponectin in gestational diabetes mellitus: a systematic review and meta-analysis. Sci World J. 2014;2014: 926932.CrossRef
112.
Greenhill C. The role of adiponectin in gestational diabetes mellitus. Nat Rev Endocrinol. 2017;13(3):128–128.PubMed
113.
Madhu SV, Bhardwaj S, Jhamb R, Srivastava H, Sharma S, Raizada N. Prediction of gestational diabetes from first trimester serum adiponectin levels in Indian women. Indian J Endocrinol Metab. 2019;23(5):536–9.PubMedPubMedCentralCrossRef
114.
Iliodromiti S, Sassarini J, Kelsey TW, Lindsay RS, Sattar N, Nelson SM. Accuracy of circulating adiponectin for predicting gestational diabetes: a systematic review and meta-analysis. Diabetologia. 2016;59(4):692–9.PubMedPubMedCentralCrossRef
115.
Yuan XS, Shi H, Wang HY, Yu B, Jiang J. Ficolin-3/adiponectin ratio for the prediction of gestational diabetes mellitus in pregnant women. J Diabetes Investig. 2018;9(2):403–10.PubMedCrossRef
116.
Chandrasekaran PR, Madanagopalan VG, Narayanan R. Diabetic retinopathy in pregnancy—a review. Indian J Ophthalmol. 2021;69(11):3015–25.PubMedPubMedCentralCrossRef
117.
Siahanidou T, Mandyla H, Papassotiriou GP, Papassotiriou I, Chrousos G. Circulating levels of adiponectin in preterm infants. Arch Dis Child Fetal Neonatal Ed. 2007;92(4):F286-290.PubMedCrossRef
118.
Yilmaz MI, Sonmez A, Kilic S, et al. The association of plasma adiponectin levels with hypertensive retinopathy. Eur J Endocrinol. 2005;152(2):233–40.PubMedCrossRef
119.
Arterburn LM, Hall EB, Oken H. Distribution, interconversion, and dose response of n-3 fatty acids in humans. Am J Clin Nutr. 2006;83(6 Suppl):1467s–76s.PubMedCrossRef
120.
Vannice G, Rasmussen H. Position of the academy of nutrition and dietetics: dietary fatty acids for healthy adults. J Acad Nutr Diet. 2014;114(1):136–53.PubMedCrossRef
121.
Yanai R, Mulki L, Hasegawa E, et al. Cytochrome P450-generated metabolites derived from ω-3 fatty acids attenuate neovascularization. Proc Natl Acad Sci USA. 2014;111(26):9603–8.PubMedPubMedCentralCrossRef
122.
Yiannikouris F, Gupte M, Putnam K, Cassis L. Adipokines and blood pressure control. Curr Opin Nephrol Hypertens. 2010;19(2):195–200.PubMedPubMedCentralCrossRef
Erhöhte kardiale Troponine gelten als Schlüsselmarker des Myokardinfarkts. In seltenen Fällen beruhen stark erhöhte Werte jedoch nicht auf einer Myokardschädigung, sondern auf Störfaktoren. Wie sollte man mit einem derartigen Verdacht umgehen?
Für die Therapie von Patientinnen – betroffen sind fast ausschließlich Frauen – mit Lipödem existiert eine Reihe von Optionen, mit einem eindeutigen Favoriten in puncto Effektivität. Ein großes Problem ist jedoch die korrekte Diagnose.
Ergebnisse einer kleinen randomisierten Studie aus den Niederlanden legen nahe, dass sich unter einer gewissen Dosisanpassung L-Thyroxin auch zum Essen einnehmen lässt, anstatt nüchtern vor der Mahlzeit. Optimalerweise würden die Ergebnisse indes noch in größeren Analysen bestätigt werden.
Massiver Gewichtsverlust, erhöhte Cholestaseparameter und ein extrem hoher Wert des Tumormarkers CA-19-9 bei einem Diabetiker werden als Zeichen eines Pankreaskarzinoms gedeutet. Doch Krebsangst und Tumorsuche hätten dem Mann erspart werden können.
