CagA-positive H. pylori may protect against disease of the hands, feet, and mouth

Fever, anorexia, and sadness are common symptoms of hand-foot and mouth disease (HFMD), which is an acute infectious disease that affects children and is brought about by enteroviral infections. This disease is characterized by skin rashes, herpes, and blisters on the feet, hands, mouth, and buttocks. Over the past several years, the prevalence of HFMD has remained extremely high in mainland China and other Asia-Pacific areas. Furthermore, the growing number of severe illnesses and fatalities that have been attributed to HFMD has garnered a significant amount of attention from across the world [1].

Hosts harboring the HFMD virus may exhibit latent infection, herpetic pharyngitis, a straightforward rash, or characteristic HFMD. Most occurrences are moderate and self-limiting, but a tiny percentage of cases progress quickly, are linked to serious problems with the central nervous system, and, in severe instances, can result in death from cardiopulmonary failure [1]. Protecting the host from HFMD virus infection is mostly dependent on innate and mucosal immunity [2]. Innate immunity and mucosal immunity are essential components in the process of safeguarding the host against HFMD viral infection [2]. On the other hand, immunity in cells is primarily responsible for the elimination of the virus within the host after the infection has been established.cellular immunity is primarily responsible for eliminating cells infected by viruses. Children with HFMD exhibit diminished levels of CD3 + T, CD4 + T, CD8 + T, CD4+/CD8+, and Th cells, particularly in severe cases, as indicated by certain studies [3, 4]. This suggests that cellular immunity is inadequate in these children. Additionally, it has been observed that the blood of patients with HFMD has a lower percentage of Treg cells. As a result, it is thought that T cell activation in patients infected with EV71 may be down-regulated, indicating that the Th1/Th2 and Th17/Treg ratios in these patients may be unbalanced [5]. After infection, the microaerobic, gram-negative bacteria known as Helicobacter pylori (H. pylori) continues to colonize the mucosa of the stomach for the rest of the patient’s life, which leads to chronic persistent infection. Recent research has increasingly concentrated on the relationship between H pylori and extra-gastrointestinal diseases [6]. Research has indicated that infections brought on by viruses including HIV, HCV, and Borrelia burgdorferi are linked to H. pylori infection [7‐9]. Additionally, studies have demonstrated that H. pylori may offer protection against tuberculosis, atopy, asthma, shigellosis, and other diarrheal illnesses [10‐12]. Childhood H. pylori infection permanently changes naïve T cells into Th1 phenotypes and causes high levels of Treg cells both locally and systemically. Treg cells are a type of cells with immunoregulatory functions that keep the immune system in balance. It provides theoretical support for the “hygiene hypothesis,” which holds that early infection exposure helps the immune system mature and makes it easier to respond to previous or current infections [10]. Besides, H. pylori needs a healthy immune system in order to colonize the human stomach mucosa successfully and persistently. Studies have shown that H. pylori-related inflammatory environment selectively increases [13] in CD4 + T cells, which plays an important role in the host’s immune response to viral infection. H. pylori expresses virulence proteins, with CagA being a significant one. It’s a key effector protein in H. pylori’s interaction with the host. CagA-positive people can also be stimulated to produce potent cytokines [14]. It has also been demonstrated that H. pylori promotes the production of IL-10 by regulatory T cells in order to regulate local inflammation and maintain immunological homeostasis [15]. This immune response is enhanced in infections caused by the cagA+/vacA s1m1 strain. These immunological pathways cause the connections between H. pylori and other infectious illnesses. Likewise, our group has shown in earlier research that scrub typhus is both facilitated and intensified by CagA + H. pylori infection due to impacts on host immunity [16].

In conclusion, the range of symptoms and clinical regression associated with HFMD varies greatly following host infection with the HFMD virus. Although the precise mechanism underlying this variation remains unclear, It has been proposed that there may be a connection among the immune system of the patient and a particular type of the HFMD virus [17, 18]. HFMD and H. pylori infections are two disorders that may be transmitted via the gastrointestinal system. For the most part, the symptoms of both conditions manifest themselves in youngsters. Our theory is that H. pylori infection may influence the host’s resistance to the HFMD virus, hence impacting the clinical spectrum of HFMD. The aim of this research was to determine if HFMD and H. pylori, particularly CagA + strains, are related.

The majority of H. pylori infections happen in childhood, and if treatment is not successful, infections frequently last a lifetime [21]. However, enterovirus-induced HFMD is more common in children under five. In clinical terms, HFMD diminishes with age, but H. pylori increases. Therefore, a thorough consideration of the potential clinical relationship between the two is warranted. We investigated the association between the two for the first time in the current study. In order to reduce the impact of age, gender, and geographic variables, we carefully matched the age, gender, and regional distribution of children with HFMD with those of healthy children who underwent medical examinations.

Children with HFMD had a substantially lower infection in the bacteria H. pylori (16.2% against 29.3%, P < 0.05) than children who had healthy check-ups, according to first-time results in this study. This suggests that H. pylori infection may have a protective effect against HFMD. Children over five years old exhibited a considerably lower likelihood of infections caused by H. pylori (18.5% compared to 41.5%, P < 0.05) than children without HFMD, according to the results of this study’s further age stratification. Still, this phenomenon was not observed in children younger than five years old. It could also be a significant factor in the frequency of HFMD declining with age and being more common in children under the age of five. The exact mechanism underlying this phenomenon remains ambiguous; nonetheless, during an intestinal H. pylori infection, neutrophils, B lymphocytes, and T lymphocytes infiltrate the stomach and duodenal mucosa. This infiltration does not result in H. pylori clearance, which could be caused by insufficient cytokine secretion or by the immune system being down-regulated because of the increased number of regulatory cells(Tregs) that are present [22]. Additional research has demonstrated that during Helicobacter infection, there is an increase in Tregs, which results in a reduction in the rate of cytokine production [23‐25]. There may be a connection between the immunosuppression of Tregs and the survival and persistence of some infectious pathogens, as evidenced by the association between increased Tregs activity and the stability of illnesses, including leishmaniasis, malaria, and tuberculosis [26]. According to the “hygiene hypothesis,” which was progressively developed by Strachan [27] and Bach [28], childhood exposure to microorganisms strengthens the immune system, may prevent the onset of autoimmune diseases in adulthood, and improves the body’s ability to respond to previous or current infections [29]. In the lack for H. pylori infection, the processes that may be participating may include, on the one hand, insufficient microbial stimulation if gut-associated lymphoid tissues, which is an essential location for the development of the mucosal immune system [30]. Conversely, childhood getting ill with H. pylori can lead to the permanent differentiation of naïve T cells into a Th1 phenotype and induce elevated levels of Treg cells both locally and systemically [10]. Innate immunity and mucosal immunity have a major role in the host’s resistance to the virus during the early stages of HFMD viral infection [2]. The “hygiene hypothesis” suggests that prior contact with H. pylori plays an instrumental part in the establishment about intestinal mucosal immunity, potentially explaining the protective effect of H. pylori getting sick against HFMD. Studies also indicate that it may exhibit a synergistic effect in conjunction with EV71 infection. Ammar M. Hassanbhai [31] et al. Constructed a model of EV71 interaction with dehydrated H. pylori biofilm to simulate the relationship between the two in the natural state of the environment. The study found that EV71 was more likely to survive and replicate in the presence of H.pylori biofilm, and that the number of biofilms determined the viral viability. This suggests that H.pylori biofilms may provide an alternate route for EV71 transmission, as the study suggests that EV71 particles are protected from degradation and inactivation by synergistic interactions with Helicobacter pylori.

Furthermore, by causing bystander effects through prolonged inflammation and T-cell signaling, H. pylori infection may enhance innate immune responses to other infectious illnesses [10]. When Listeria monocytogenes and Yersinia pestis attack mice, infectious diarrhea rarely occurs, similar to mice with herpesvirus infection [10].

While most childhood H. pylori infections do not cause any symptoms, a small percentage of infected people get gastrointestinal or extragastrointestinal disease. An assortment of variables may be at issue here, like the genetic composition of the hosts and the aggressiveness of those from H. pylori strains, namely the CagA + ones [14]. We used immunoblotting to figure out the presence of H. pylori strains while investigating the association involving these strains and HFMD in this research. The findings revealed that HFMD patients were more likely to have a smaller percentage of H. pylori CagA + strain infection compared to healthy control (8.5% vs. 18.0%, P < 0.05). likewise, in children who were over five years old, HFMD children were more bound to have a lower prevalence of CagA + H. pylori infection than healthy control (9.3% vs. 26.6%, P < 0.05), with a statistically significant difference. The results of multivariate regression analyses strengthened the hypothesis that H. pylori CagA + strain infection was a protective marker for HFMD. The results indicate that pylori bacteria harboring the CagA gene may confer an immune defense against HFMD, although it is unclear exactly how this protective effect works. According to research, H. pylori infections mostly cause a Th1/Th17 response [15]. Moreover, infections with the cagA+/vacA s1m1 strain had a stronger immune response than those with the cagA-/vacA s2/m2 strain [15]. IL-17 expressed following an infestation of H. pylori has been illustrated to increase early host resistance to Mycobacterium colonization in LTBI and trigger T-cell migration to the lungs [15]. On the other hand, Kienesberger et al. [32] also discovered that a significant factor in either tuberculosis susceptibility or protection is the H. pylori-induced migration of Treg and Th17 cells to distant regions, particularly high pathogenicity (CagA+) strains. We hypothesized that H. pylori infection harboring the the enzyme CagA gene contributes to the pathogenesis of HFMD via a comparable mechanism.

In the final analysis, HFMD patients had a considerably lower prevalence of H.pylori infection juxtaposed to the appropriate population. Furthermore, the type I H.pylori strain has been demonstrated to be an standalone safeguarding factor for the emergence of HFMD, demonstrating that H.pylori transporting the CagA gene might constitute an inhibitor of infection.

This study might have some drawbacks. The present investigation employed the immunoblotting approach, which is user-friendly and possesses high specificity and sensitivity, to determine the blood H. pylori antibodies and identify its strains. However, studies utilizing serology are also vulnerable to data bias, and we did not conduct duplicate testing to decrease error. Second, this paper only examined serological testing as our primary method of data analysis. It did not include other potential risk factors for H. pylori infection, in particular the family revenue, antibiotic usage, as well as the existence or absence of a presenting ailments.