Abstract
Increasing evidence has noted that neuroinflammation contributes to the pathological processes of cognitive impairment of obstructive sleep apnea (OSA) patients. Interleukin (IL) -33/suppression of tumorigenicity 2 (ST2) signaling pathway plays well-defined roles in the inflammatory progression. The study aims to elucidate whether IL-33/ST2 signaling pathway plays a role in the cognitive dysfunction in patients with OSA via regulating neuroinflammation. We found that compared with control subjects, patients with OSA showed significantly elevated IL-33, ST2 and p65 nuclear factor-kappa B (NF-κB) levels in peripheral blood mononuclear cells (PBMCs) and inflammatory cytokines IL-6, IL-8 in serum, which were positively correlated with disease severity. Meanwhile, OSA patients exhibited a decline in Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores, suggesting mild cognitive impairment. Continuous positive airway pressure (CPAP) treatment for 12 weeks significantly decreased the expression of IL-33, ST2, p65NF-κB, IL-6 and IL-8, as well as improved cognitive function of OSA patients. Moreover, the IL-33/ST2 signaling was closely correlated with sleep respiratory parameters and cognitive dysfunction. To further explore the underlying mechanism of IL-33/ST2 signaling pathway, we stimulated human microglial clone 3 (HMC3) cells with lipopolysaccharide (LPS) to mimic neuroinflammatory response in vitro. The results showed that LPS treatment led to an increase in IL-33 and ST2 expression in a dose- dependent manner, along with an increased secretion of IL-6 and IL-8. Functional experiments showed that knockdown of IL-33 ameliorated LPS-induced neuroinflammation via suppressing NF-κB signaling. Overall, current findings suggest that IL-33/ST2 signaling participated in the cognitive impairment of OSA patients by promoting neuroinflammation via activating NF-κB signaling. These results may provide a novel therapeutic target for treating OSA- associated cognitive dysfunction.