Targeting the mechanistic target of rapamycin complex 1 restricts pro-inflammatory T cell differentiation and ameliorates Takayasu's arteritis.

Objective Takayasu arteritis (TAK) is a progressive autoimmune large vessel vasculitis with infiltration of proinflammatory T cells, with a largely unknown etiology. This study was undertaken to explore the involvement of mechanistic target of rapamycin (mTOR) in proinflammatory T cell differentiation and disease progression in TAK. Methods Ninety-five patients with TAK, 26 patients with small vessel vasculitis, and 40 healthy donors were enrolled. Naive and memory CD4+ T cells were activated with anti-CD3/CD28 beads and analyzed for lineage differentiation. The mTORC1 activity was determined by quantifying intracellular phospho-S6 kinase 1 and phospho-S6 ribosomal protein. Rapamycin and lentiviral regulatory-associated protein of mTOR short hairpin RNA were used to block mTORC1 activity. Human artery-NSG mouse chimeras representing human TAK were established for targeting mTORC1 in disease treatment. Results TAK CD4+ T cells were selectively prepositioned with hyperactivity of mTORC1 (P < 0.001), resulting in spontaneous maldifferentiation of Th1 and Th17 cells (P < 0.001). Activity of mTORC1(high) in circulating CD4+ T cells predicted elevated frequencies of proinflammatory T cells and active disease in TAK patients (P < 0.001). Blockade of mTORC1 with rapamycin efficiently abrogated the maldifferentiation of Th1 and Th17 cells (P < 0.01) and ameliorated vasculitis in humanized TAK chimeras (P < 0.001). Inhibition of mTORC1 using RNA interference technology is sufficient to reduce proinflammatory T cell frequencies (P < 0.01) and restrict TAK disease progression in vivo (P < 0.01). Conclusion Our findings indicate that hyperactivity of mTORC1 is a critical cell-intrinsic mechanism underlying spontaneous maldifferentiation of proinflammatory T cells in TAK patients. Targeting mTORC1 is a promising therapeutic strategy against TAK.