Restraint Stress-Induced Neutrophil Inflammation Contributes to Concurrent Gastrointestinal Injury in Mice.

Psychological stress increases risk of gastrointestinal tract diseases. However, the mechanism behind stress-induced gastrointestinal injury is not well understood. The objective of our study is to elucidate the putative mechanism of stress-induced gastrointestinal injury and develop an intervention strategy. To achieve this, we employed the restraint stress mouse model, a well-established method to study the pathophysiological changes associated with psychological stress in mice. By orally administering gut-nonabsorbable Evans blue dye and monitoring its plasma levels, we were able to track the progression of gastrointestinal injury in live mice. Additionally, flow cytometry was utilized to assess the viability, death, and inflammatory status of splenic leukocytes, providing insights into the stress-induced impact on the innate immune system associated with stress-induced gastrointestinal injury. Our findings reveal that neutrophils represent the primary innate immune leukocyte lineage responsible for stress-induced inflammation. Splenic neutrophils exhibited elevated expression levels of the pro-inflammatory cytokine IL-1, cellular reactive oxygen species, mitochondrial burden, and cell death following stress challenge compared to other innate immune cells such as macrophages, monocytes, and dendritic cells. Regulated cell death analysis indicated that NETosis is the predominant stress-induced cell death response among other analyzed regulated cell death pathways. NETosis culminates in the formation and release of neutrophil extracellular traps, which play a crucial role in modulating inflammation by binding to pathogens. Treatment with the NETosis inhibitor GSK484 rescued stress-induced neutrophil extracellular trap release and gastrointestinal injury, highlighting the involvement of neutrophil extracellular traps in stress-induced gastrointestinal inflammation. Our results suggest that neutrophil NETosis could serve as a promising drug target for managing psychological stress-induced gastrointestinal injuries.

Restraint Stress-Induced Immunosuppression Is Associated with Concurrent Macrophage Pyroptosis Cell Death in Mice.

Psychological stress is widely acknowledged as a major contributor to immunosuppression, rendering individuals more susceptible to various diseases. The complex interplay between the nervous, endocrine, and immune systems underlies stress-induced immunosuppression. However, the underlying mechanisms of psychological-stress-induced immunosuppression remain unclear. In this study, we utilized a restraint stress mouse model known for its suitability in investigating physiological regulations during psychological stress. Comparing it with cold exposure, we observed markedly elevated levels of stress hormones corticosterone and cortisol in the plasma of mice subjected to restraint stress. Furthermore, restraint-stress-induced immunosuppression differed from the intravenous immunoglobulin-like immunosuppression observed in cold exposure, with restraint stress leading to increased macrophage cell death in the spleen. Suppression of pyroptosis through treatments of inflammasome inhibitors markedly ameliorated restraint-stress-induced spleen infiltration and pyroptosis cell death of macrophages in mice. These findings suggest that the macrophage pyroptosis associated with restraint stress may contribute to its immunosuppressive effects. These insights have implications for the development of treatments targeting stress-induced immunosuppression, emphasizing the need for further investigation into the underlying mechanisms.