A double-edged sword role of IFN-?-producing iNKT cells in sepsis: Persistent suppression of Treg cell formation in an Nr4a1-dependent manner
Sepsis, a leading cause of mortality in intensive care units worldwide, lacks effective treatments for advanced-stage sepsis. Therefore, understanding the underlying mechanisms of this disease is crucial. This study reveals that iNKT cells have an opposing role in the progression of sepsis by suppressing Treg differentiation and function. The activation of iNKT cells by a-Galcer enhances IFN-? production. Blocking antibodies or transferring IFN-?-deficient iNKT cells demonstrates that iNKT cells inhibit Treg differentiation through IFN-? production. Additionally, iNKT cell-mediated Treg inhibition prevents secondary infection caused by Listeria monocytogenes during the post-septic phase. The transcriptomic analysis of Tregs further reveals that the suppressive function of Tregs is impaired by iNKT cells. Finally, we demonstrate that iNKT cells inhibit Treg differetiation in a Nr4a1-dependent manner. Our data uncover the dual function of iNKT cells in sepsis progression and provide a potential treatment target for this adverse long-term outcome induced by sepsis. Overall design: The CD4+ T cells were isolated from splenocytes of septic mice treated with a-galcer or PBS (two days after CLP performance) using the negative CD4+T cell isolation kit, following the manufacturer's instructions. Subsequently, the Treg cell population, characterized by CD25highCD127low markers, was sorted using BD FACSAria™ Fusion Flow Cytometers. To ensure an adequate number of enriched Treg cells, Treg cells were collected from three mice. The isolated Treg cells with a purity about 90% were subjected to TRIzol treatment, and total RNA was extracted according to the manufacturer's protocol.