Profiling Associations Between IGHG-FCGR Ligand-Receptor Interactions and Disease Progression From Stage 1 and 2 to Stage 3 Type 1 Diabetes

The primary objective of this study was to investigate whether ligand-receptor interactions (LRIs) between IGHG and FCGR gene products are associated with progression to type 1 diabetes (T1D). Using two completed clinical trials (DPT-1 and TN07), we applied next-generation targeted sequencing to genotype IGHG and FCGR genes in a cohort of 1,214 individuals and assessed LRI associations with disease progression. A Cox regression model was used to quantify LRI associations. IGHG or FCGR alone was found to have weak and sporadic associations with progression. Multiple LRIs between IGHG and FCGR gene products were found to be associated with progression, especially LRIs of IGHG2 with multiple FCGR receptors that accelerate progression and those of IGHG4 with multiple FCGR receptors (some overlapping) that delay progression. Furthermore, as several crystal structures of FcγRs complexed with distinct IgG molecules are known, application of this knowledge here was hampered by the absence of any information on the subclass distribution of each of the several T1D-related autoantibodies. It cannot be excluded that their respective state of glycosylation may influence binding affinity to various FcγRs and the function of thus-formed complexes. Our findings suggest that LRIs of the IGHG and FCGR gene products probably influence progression, shedding new insights into some of the immunological mechanisms involved in progression to T1D. Our findings potentially facilitate the search for new immunotherapeutic treatment through intervening at key steps in the progression. Article Highlights This study investigated ligand-receptor interactions (LRIs) between IGHG and FCGR gene products in type 1 diabetes progression. Genes of 1,214 participants from the DPT-1 and TN07 trials were sequenced using next-generation targeted sequencing technology, and LRI associations with the progression time to type 1 diabetes were analyzed using Cox regression modeling. Weak associations were found for IGHG or FCGR variants individually, but multiple LRIs significantly impacted progression. Several IGHG2-FCGR interactions accelerated progression, while a few other IGHG4-FCGR interactions delayed it. The results may provide insights into certain immunogenetic mechanisms of T1D and suggest therapeutic potential of targeting specific LRIs.