Identification of potential hub genes linked to immune and metabolic alterations in postoperative systemic inflammatory dysregulation

S100A12 triggers NETosis to aggravate myocardial infarction injury via the Annexin A5-calcium axis

Neutrophil extracellular traps (NETs) play a critical role in acute myocardial infarction (AMI) and the externalization of S100 family members. Here, we show the effects of S100A12 on NETs formation and myocardial injury following AMI. S100A12 expression increases rapidly in neutrophils and peaks on day 1 after AMI, promoting NETs production and exacerbating myocardial injury. DNase I, an inhibitor of NETs, reduces apoptosis of cardiomyocytes induced by S100A12. Mechanistically, the interaction of S100A12 and Annexin A5 (ANXA5) enhances calcium influx and promotes NETs formation. Blockage of ANXA5 effectively attenuates heart function impairment after AMI. Finally, we show that plasma S100A12 levels correlate with dsDNA concentration, and this correlation is associated with an increased risk of all-cause mortality during the 1-year follow-up of AMI patients. These findings, derived from male mice, reveal the S100A12-ANXA5-calcium influx axis as a potential therapeutic target and biomarker for AMI.

Early dynamic changes to monocytes following major surgery are associated with subsequent infections

Background

Post-operative infections are a common cause of morbidity following major surgery. Little is understood about how major surgery perturbs immune function leading to heightened risk of subsequent infection. Through analysis of paired blood samples obtained immediately before and 24 h following surgery, we evaluated changes in circulating immune cell phenotype and function across the first 24 h, to identify early immune changes associated with subsequent infection.

Methods

We conducted a prospective observational study of adult patients undergoing major elective gastrointestinal, gynecological, or maxillofacial surgery requiring planned admission to the post-anesthetic care unit. Patients were followed up to hospital discharge or death. Outcome data collected included mortality, length of stay, unplanned intensive care unit admission, and post-operative infections (using the standardized endpoints in perioperative medicine-core outcome measures for perioperative and anesthetic care criteria). Peripheral blood mononuclear cells were isolated prior to and 24 h following surgery from which cellular immune traits including activation and functional status were assessed by multi-parameter flow cytometry and serum immune analytes compared by enzyme-linked immunosorbent assay (ELISA).

Results

Forty-eight patients were recruited, 26 (54%) of whom developed a post-operative infection. We observed reduced baseline pre- and post-operative monocyte CXCR4 and CD80 expression (chemokine receptors and co-stimulation markers, respectively) in patients who subsequently developed an infection as well as a profound and selective post-operative increase in CD4+ lymphocyte IL-7 receptor expression in the infection group only. Higher post-operative monocyte count was significantly associated with the development of post-operative infection (false discovery rate < 1%; adjusted p-value = 0.001) with an area under the receiver operating characteristic curve of 0.84 (p < 0.0001).

Conclusion

Lower monocyte chemotaxis markers, higher post-operative circulating monocyte counts, and reduced co-stimulatory signals are associated with subsequent post-operative infections. Identifying the underlying mechanisms and therapeutics to reverse defects in immune cell function requires further exploration.