Genetic risk and inflammatory signaling converge on cell type-specific regulatory programs in type 1 diabetes

Type 1 diabetes (T1D) is a complex autoimmune condition that involves the destruction of insulin-producing pancreatic beta cells. Both genetic susceptibility and epigenetic dysregulation play a role in increasing the risk of T1D. Recent research has shown that beta-cell dysfunction can occur before the onset of the disease, indicating that mechanisms within the beta cells themselves may contribute to its development.

However, the precise link between disease-associated genetic variants and beta-cell dysfunction is not yet fully understood. Researchers hypothesized that certain T1D-linked variants might directly impact cell type-specific candidate cis-regulatory elements (cCREs) by interfering with transcription factor (TF) binding and modifying gene expression.

To investigate this, the researchers integrated various epigenomic datasets, including bulk histone modification profiles and single-cell multiomic data derived from human pancreatic islets. By combining these datasets with genetic information from genome-wide association studies (GWAS) focused on T1D, they were able to pinpoint disease-associated SNPs situated within enhancer regions.

Using advanced single-cell multiomic datasets from the PANC-DB database, the scientists characterized chromatin accessibility differences between islets from non-diabetic individuals and those with T1D. They aimed to identify regulatory regions that could potentially control gene expression in beta cells and other islet cell types.

Employing ChromBPNet, a sophisticated deep learning model capable of predicting chromatin accessibility at a base-pair resolution from single-cell ATAC-seq data, the researchers evaluated how specific genetic variants might disrupt local regulatory activity in these regions. Simultaneously, they utilized TF footprinting to identify transcription factors that were likely to bind these variant-containing regions.

The combined analyses revealed that several T1D-associated SNPs are predicted to alter chromatin accessibility at sites near candidate TF binding locations. This suggests potential mechanisms by which noncoding variants may contribute to beta-cell dysfunction and the overall susceptibility to T1D. The findings underscore the connection between T1D-associated genetic variants and cell type-specific enhancer activity, offering promising leads for future mechanistic studies aimed at understanding the disease at a deeper level.