PROJECT SUMMARY
Type 1 diabetes (T1D) is a chronic autoimmune disease of unknown etiology leading to the destruction of
pancreatic beta cells, which secrete insulin and regulate glucose homeostasis. The incidence of T1D has been
increasing over the years, a trend inexplicable by only genetic predisposition, suggesting that environmental
factors such as viruses play an important role in triggering the disease. Decades of research have provided
epidemiological evidence for an association between T1D and viruses, particularly coxsackieviruses of the
Enterovirus genus. Patients with T1D had higher rates of antibodies anti-CVB, viral RNA and viral capsid protein
compared to non-diabetic. Studies have also shown that children who had developed islet autoantibodies had
more CVB infections. Viral infection can impact beta cells through a direct cytolytic effect or by bystander
activation of the immune system leading to gradual destruction. However, there is still little direct causal evidence
from human pancreata that would establish a link between viral infections and T1D development. Although
mouse studies have been very useful in understanding some of the mechanisms of the disease, there remain
substantial gaps and differences to human pathology. Therefore, studies on Human pancreatic tissue samples
become essential. Pancreas tissue slices are 150-200 µm thick sections of living human donor pancreatic tissue.
They enable functional analysis of intact islets in their endogenous environment and 3D morphological
assessment of the endocrine and exocrine pancreas as well as the blood vasculature, neurons and tissue
resident immune cells. In preliminary studies, we have been able to culture and infect Human pancreatic slices
using coxsackievirus B3 (CVB3)-GFP and identify the beta cells and tissue-resident macrophages as targets.
Thus, we hypothesize that virus infections induce changes in tissue-resident macrophages which then induce T
cells to attack and destroy beta cells. Aim 1 will evaluate the impact of CVB3-GFP infection on beta cells
function and viability. Aim 2 will characterize tissue-resident macrophages during CVB3 infection by single cell
RNA-seq. Aim 3 will examinate if the infection could lead to an immune destruction of beta cells when cocultured
with HLA matched or autologous PBMCs. Aim 4 will characterize the impact of CVB3 infection on autophagy
in infected Human pancreatic slices. Overall, this effort will generate a better understanding of the consequences
of viral infections in the pancreas and its role in the onset of T1D.
