Bhlhe40 promotes inflammatory property of ILC2s through differential regulation of IL-10 and GM-CSF expression 2308383

Abstract Introduction ILC2s (group 2 Innate lymphoid cells) are involved in type 2 immune responses during both phases of innate and adaptive response. The transcription factor Bhlhe40 has been reported to regulate the balance between inflammatory and anti-inflammatory reactions in CD4 T cells. However, although Bhlhe40 is also expressed by ILC2s, its functions in these cells are unknown. Methods By challenging Bhlhe40-germline knockout mice and ILC2-specific Bhlhe40 knockout mice with papain acutely, we found that eosinophils were reduced in these mice compared to their wild type controls, indicating that Bhlhe40 is required for ILC2 function in recruiting eosinophils in response to papain-induced lung damage. Results Interestingly, the expression of IL-5 known for recruiting eosinophils was not altered in Bhlhe40 deficient ILC2s. Instead, we found a reduction in GM-CSF expression but an increase in IL-10 production in the absence of Bhlhe40. To get a clearer picture of how Bhlhe40 regulates ILC2 function, we performed scRNA-seq and scATAC-seq of WT and Bhlhe40 knockout ILC2s, and found Bhlhe40 affected ILC2 subsets and regulated gene expression in distinct clusters of ILC2s. Further analysis of the Il10 locus identified several interesting elements at the Il10 promoter/enhancer regions that had differential gene accessibility between WT and knockout. Furthermore, we confirmed that Bhlhe40 can directly bind to Il10 locus in ILC2s by ChIP-Seq. On the other hand, no obvious changes in DNA accessibility were noted at the Csf2 (encoding GM-CSF) locus, suggesting Bhlhe40 may indirectly regulate GM-CSF expression. Conclusion Overall, our results demonstrate that just as its function in T cells, Bhlhe40 also regulates the balanced expression of inflammatory and anti-inflammatory cytokines in innate lymphoid cells. Funding Source n/a Topic Categories Innate Immune Responses and Host Defense: Molecular Mechanisms (INM)