Semaphorin3A Rewires CD4+ T-Cell Metabolism via AKT/mTORC1 Inhibition in Health and Rheumatoid Arthritis.

Semaphorin3A (Sema3A) is a regulatory protein found to be expressed on regulatory T and B cells and also secreted into peripheral blood. It has been identified as a potent immune regulator; however, not all its regulatory mechanisms have been evaluated. In this respect, we aim to investigate how Sema3A affects key metabolic pathways in T cells during homeostasis and rheumatoid arthritis (RA), and on the AKT/mTORC1 signaling axis. In this study, peripheral blood samples were collected from 119 healthy donors and 32 rheumatoid arthritis patients. T cells were subjected to Seahorse analysis to evaluate OXPHOS and glycolysis, live cell TMRE staining to evaluate mitochondrial activity, mass spectrometry for metabolite profiling, ATP determination to study ATP production, and Western blot analysis to investigate the signaling pathway activity. This study presents evidence showing that Sema3A inhibits the AKT/mTORC1 pathway, leading to a decreased glucose uptake and glycolysis disruption. Furthermore, we show that Sema3A reduces mitochondrial capacity and OXPHOS in activated T cells of healthy and RA donors, leading to a decreased ATP production. In contrast, Sema3A upregulates fatty acid oxidation (FA), probably as a backup pathway to ensure cell survival. Results with p values of <0.05 were considered significant. Our data may point to Sema3A's ability to convert activated T cells' metabolic profile back to its non-activated state. This may suggest that Sema3A might be a beneficial treatment for immune-mediated diseases by metabolically reprogramming activated T cells.