Heat shock protein 90α reduces CD8⁺ T cell exhaustion in acute lung injury induced by lipopolysaccharide

CD8⁺ T-cell exhaustion is a promising prognostic indicator of sepsis-induced acute respiratory distress syndrome (ARDS). Patients with sepsis-related ARDS had reduced levels of HSP90AA1. However, whether the changes in CD8⁺ T cells were related to HSP90α, encoded by the HSP90AA1 gene, was unclear. This study aimed to examine the regulatory mechanism of HSP90α and its impact on CD8⁺ T-cell exhaustion in lipopolysaccharide (LPS)-induced acute lung injury (ALI). In this study, by conducting a mouse model of ALI, we found that one week after LPS-induced ALI, CD8⁺ T cells showed exhaustion characteristics. At this time, proliferation and cytokine release in CD8⁺ T cells were reduced. The inhibitory costimulatory factors PD-1 and Tim-3, on the other hand, were enhanced. Meanwhile, the expression of HSP90α and STAT1 decreased significantly. The in vitro studies showed that HSP90α stimulation or inhibition affected the CD8⁺ T-cell exhaustion phenotype. Interference with STAT1 reduced the expression of HSP90α and impaired its regulation of CD8⁺ T cells. The Co-Immunoprecipitation results indicated that HSP90α can directly or indirectly bind to TOX to regulate TOX expression and downstream signal transduction. In summary, by inhibiting TOX-mediated exhaustion signaling pathways, HSP90α inhibited CD8⁺ T-cell exhaustion in ALI. The participation of STAT1 in the regulation of HSP90α was required.