| Summary |
Type 1 diabetes (T1D) is an autoimmune disease characterized by the destruction of pancreatic insulin-producing β cells. CD4+ T cells are integral to the pathogenesis of T1D, but biomarkers that define their pathogenic status in T1D are lacking. miRNAs have essential functions in a wide range of tissues/organs, including the immune system. We reasoned that CD4+ T cells from individuals at high risk for T1D (pre-T1D) might be distinguished by an miRNA signature. We sorted CD4+ T cells from 9 healthy and 7 pre-T1D individuals into 6 subsets, namely naïve, resting regulatory (rTreg), activated regulatory (aTreg), transitional memory (Ttm), central memory (Tcm) and effector memory (Tem) cells, and then compared miRNA profiles between these subsets and between pre-T1D and healthy individuals by deep sequencing. Differential expression of miRNAs was detected in each of the CD4+ T cell subsets. For example, expression of miRNAs that induce apoptosis (miR-15a) or FOXP3 instability (miR-31) was increased in rTreg and aTreg cells, respectively, in pre-T1D individuals, whereas miR-150 was increased in Tem cells of pre-T1D individuals. Importantly, increased miR-150 expression could be detected by qRT-PCR in total CD4+ T and PBMCs of pre-T1D individuals. Consistent with it being a marker of pathogenic CD4+ T cells, we showed that miR-150 regulates IFN-γ production in mouse CD4+ T cells. Thus, comprehensive profiling identifies miRNA profiles that not only distinguish CD4+ T cell subsets but also discriminate individuals with preclinical T1D. The ability to detect differentially expressed miRNAs in total CD4+ T cells or PBMCs should facilitate clinical application of miRNAs as biomarkers.
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