Single-cell transcriptomics reveals markers of regulatory T cell dysfunction in Gestational Diabetes Mellitus

Abstract

Gestational diabetes mellitus (GDM) is a common pregnancy complication associated with hyperglycaemia, chronic inflammation and adverse health outcomes. Regulatory T cells (Tregs) are thought to contribute to GDM due to their role in suppressing inflammation. However, it remains unclear whether specific Treg subsets are impaired in patients with GDM. To investigate transcriptional variation in GDM Tregs, we applied single-cell RNA sequencing to Tregs isolated from the blood of 13 healthy pregnant women and 10 patients with GDM. We identified naive and effector Treg subsets, none of which significantly differ in the proportion of cells captured from GDM and controls. We report a naive Treg subset with reduced expression of AP-1 transcription factor subunits in GDM, including JUN, FOS, and EGR1, and an effector Treg subset with increased signalling of angiogenesis marker genes. Genes dysregulated in GDM Tregs independently predicted GDM status in pseudobulk and whole blood mRNA from independent cohorts. Remarkably, TXNIP, which regulates glucose levels, emerged as the most reliable standalone predictor in bulk mRNA (minimum AUC 0.7) equivalent to using body mass index (AUC 0.72) in our cohort. This study uncovers a disrupted molecular pathway in Treg cell subsets from GDM patients and proposes a panel of genes with translational potential as early disease biomarkers.