Enteroviral infections are associated with an increased risk to develop type 1 diabetes. Several stains of enteroviruses are able to infect beta cells leading to both inflammation and cell death, two major factors for the onset of type 1 diabetes (T1D). The cellular factors that modulate cellular permissiveness to enteroviral infection and beta cell death remain largely unknown. Since ER stress is involved in beta cell death and viral infections induce ER stress in other cell types, the aim of this project is to address the role of ER stress in virally induced beta cell death and local inflammation.

For this purpose, we will first determine whether components of the unfolded protein response (UPR) are induced during beta cell infection with a diabetogenic coxsackievirus (CVB5). Our preliminary data indicate an increase in CHOP, Bip and XBP1s mRNA expression in infected INS-1E cells. These results must be confirmed at the protein level and the activated UPR pathways further detailed.

Second, the role of the putative viral-induced ER stress in beta cell death and release of inflammatory mediators will be addressed by modulation of their expression through a silencing/overexpression approach and further evaluation of cell viability after CVB5 infection. These experiments, and the above described experiments, to be initially made in INS-1E cells, will be confirmed in primary rat and human beta cells. The accumulation of the involved ER stress markers in CVB5-infected beta cells, as well as co-detection of the capsid viral protein, will be evaluated by immunohistochemistry. To confirm the in vivo relevance of these observations, we will evaluate the co-localisation of the involved ER stress markers with viral capsid proteins in sections of pancreas from controls and coxsackievirus infected- and non infected-T1D donors. Altogether these results should shed light on the role of ER stress in beta cell death during coxsackievirus infection.