NLRP3 inflammasome-mediated premature immunosenescence drives diabetic vascular aging dependent on the induction of perivascular adipose tissue dysfunction.

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The vascular aging process accelerated by type 2 diabetes mellitus (T2DM) is responsible for the elevated risk of associated cardiovascular diseases (CVDs). Metabolic disorder-induced immune senescence has been implicated in multi-organ/tissue damage. Herein, we sought to determine the role of immunosenescence in diabetic vascular aging and to investigate the underlying mechanisms. Aging hallmarks of the immune system appear prior to the vasculature in streptozotocin (STZ)/high-fat diet (HFD)-induced T2DM mice or db/db mice. Transplantation of aged splenocytes or diabetic splenocytes into young mice triggered vascular senescence and injury compared to normal control splenocyte transfer. RNA-seq profile and validation in immune tissues revealed that the Toll-like receptor 4 (TLR4)- Nuclear factor-kappa B (NF-κB) -NLRP3 axis might be the mediator of diabetic premature immunosenescence. The absence of Nlrp3 attenuated immune senescence and vascular aging during T2DM. Importantly, senescent immune cells, particularly T cells, provoked perivascular adipose tissue (PVAT) dysfunction and alternations in its secretome, which in turn impair vascular biology. In addition, senescent immune cells may uniquely affect vasoconstriction via influencing PVAT. Lastly, rapamycin alleviated diabetic immune senescence and vascular aging, which may be partly due to NLRP3 signaling inhibition. These results indicated that NLRP3 inflammasome-mediated immunosenescence precedes and drives diabetic vascular aging. The contribution of senescent immune cells to vascular aging is a combined effect of their direct effects and induction of PVAT dysfunction, the latter of which can uniquely affect vasoconstriction. We further demonstrated that infiltration of senescent T cells in PVAT was increased and associated with PVAT secretome alterations. Our findings suggest that blocking the NLRP3 pathway may prevent early immunosenescence and thus mitigate diabetic vascular aging and damage, and targeting senescent T cells or PVAT might also be the potential therapeutic approach.