Correspondence: Piacentini M (mauro.piacentini@uniroma2.it)
Background/Rationale
Transglutaminase 2 (TG2), the most ubiquitous member of the TG family, plays a crucial role in Cystic Fibrosis (CF) pathogenesis. TG2 is a multifunctional enzyme involved in a variety of cellular processes by playing a key regulatory role in intracellular proteostasis under stressful conditions. TG2 catalyses post-translational modifications of proteins through both Ca2+ dependent and independent reactions. In fact, in addition to its crosslinking activity, TG2 may also act as protein disulphide isomerase [1]. It has been demonstrated that TG2 is constitutively up regulated in CF airways and drives chronic inflammation. The enzyme deregulation in CF disrupts the TG2 mediated capability of fighting stress, making TG2 a harmful, instead of beneficial, player of the disease pathogenesis [2]. Several TG2 inhibitors can ameliorate the disease phenotype such as cysteamine, a small molecule with pleiotropic functions, among which the capability of controlling TG2 overactivation in CF improving the trafficking and the function of F508del CFTR [3].
Hypothesis and Objectives
The aim of this project is to elucidate the molecular mechanisms by which cysteamine modulates CFTR trafficking and consequently the susceptibility to opportunistic airways infections. We will assess the activity of cysteamine against bacterial infection and the effect on the activation of the innate immune response analysing the STING pathway in the CF models. Moreover, we will perform a transcriptome sequencing in human and mouse CF models using cysteamine to inhibit TG2 with the aim to obtain a platform of new possible CF targets.
Essential methods
We will use CF mouse models infected in vivo and ex vivo with Mabs and P. aeruginosa as well as peripheral blood mononuclear cell from CF patients.
Results
Our findings indicate that cysteamine can improve the clearance of other pathogenic mycobacteria such as Mycobacterium abscessus. Moreover, we found that TG2 is able to control the innate immune response by regulating type 1 interferon production, thus possibly explaining the negative role of the enzyme in the infection process.
Conclusions
The results of this project will define the molecular basis that supports the use of cysteamine not only as a CFTR corrector but also as a promising therapy against bacterial opportunistic infections [4, 5]. To understand the molecular pathway involved in bacterial infection could provide new possible targets and the possibility to define novel strategies aimed to improve the health care of CF patients.
Reference
1. Rossin F, Villella VR, D'Eletto M, Farrace MG, Esposito S, Ferrari E, Monzani R, Occhigrossi L, Pagliarini V, Sette C, Cozza G, Barlev NA, Falasca L, Fimia GM, Kroemer G, Raia V, Maiuri L, Piacentini M. 2018. TG2 regulates the heat-shock response by the post-translational modification of HSF1. EMBO Rep. 19.
2. Luciani, A., Villella, V. R., Esposito, S., Brunetti-Pierri, N., Medina, D., Settembre, C., Gavina, M., Pulze, L., Giardino, I., Pettoello-Mantovani, M., D'Apolito, M., Guido, S., Masliah, E., Spencer, B., Quaratino, S., Raia, V., Ballabio, A. and Maiuri, L. (2010). Defective CFTR induces aggresome formation and lung inflammation in cystic fibrosis through ROS-mediated autophagy inhibition. Nat. Cell Biol. 12, 863-75.
3. Tosco, A., De Gregorio, F., Esposito, S., De Stefano, D., Sana, I., Ferrari, E., Sepe, A., Salvadori, L., Buonpensiero, P., Di Pasqua, A., Grassia, R., Leone, C. A., Guido, S., De Rosa, G., Lusa, S., Bona, G., Stoll, G., Maiuri, M. C., Mehta, A., Kroemer, G., Maiuri, L. and Raia, V. (2016). A novel treatment of cystic fibrosis acting on-target: cysteamine plus epigallocatechin gallate for the autophagy-dependent rescue of class II-mutated CFTR. Cell Death Differ. 23, 1380-93.
4. Palucci I, Matic I, Falasca L, Minerva M, Maulucci G, De Spirito M, Petruccioli E, Goletti D, Rossin F, Piacentini M, Delogu G. 2018. Transglutaminase type 2 plays a key role in the pathogenesis of Mycobacterium tuberculosis infection. J Intern Med. 283, 303-313.
5. Ferrari E, Monzani R, Villella VR, Esposito S, Saluzzo F, Rossin F, D'Eletto M, Tosco A, De Gregorio F, Izzo V, Maiuri MC, Kroemer G, Raia V, Maiuri L. 2017. Cysteamine re-establishes the clearance of Pseudomonas aeruginosa by macrophages bearing the cystic fibrosis-relevant F508del-CFTR mutation. Cell Death Dis. 8, e2544.
Acknowledgment FFC#10/2018 funded by FFC and supported by Delegazione FFC di Napoli San Giuseppe Vesuviano e Associazione “Gli amici della Ritty" Casnigo