Tregs dysfunction aggravates postoperative cognitive impairment in aged mice

ObjectivesEnhanced neuroinflammation is an important mechanism underlying perioperative neurocognitive disorders. Regulatory T cells (Tregs) play a crucial role in regulating systemic immune responses. The present study was aimed to investigate the participation of Tregs in the development of postoperative cognitive dysfunction (POCD).MethodsSurgery-associated neurocognitive disorder was induced in 18-month-old mice subjected to internal fixation of tibial fracture. Morris water maze was used to examine mice cognitive function. Splenic Tregs were collected for RNA sequencing and flow cytometry. Levels of inflammatory factors in the circulation and hippocampus were measured by enzyme-linked immunosorbent assay. Protein presences of tight junction proteins were detected by immunofluorescence.ResultsSurgery of internal fixation of tibial fracture induced cognitive impairment in aged mice, accompanied by elevated plasma levels of inflammatory factors and increased circulating Tregs. Transfusion of Tregs from young mice partially restored the structure of the blood-brain barrier and alleviated POCD in aged mice. Compared with young Tregs, differentially expressed genes in aged Tregs were enriched in tumor necrosis factor (TNF) signaling pathway and cytokine-cytokine receptor interaction. Flow cytometry revealed that aged Tregs had blunted functions under basal and stimulated conditions. Blockade of the CD25 epitope protected the blood-brain barrier structure, reduced TNF-alpha levels in the hippocampus, and improved surgery-associated cognition in aged mice.ConclusionsBlocking peripheral regulatory T cells improves surgery-induced cognitive function in aged mice. Therefore, aged Tregs play an essential role in the occurrence of POCD.

Automated summary

This study aimed to investigate the involvement of regulatory T cells (Tregs) in the development of postoperative cognitive dysfunction (POCD). The findings from animal experiments demonstrated that POCD in aged mice was accompanied by elevated levels of inflammatory factors and increased circulating Tregs. Transfusion of Tregs from young mice partially restored the blood-brain barrier structure and alleviated POCD in aged mice, indicating a crucial role of aged Tregs in the occurrence of POCD.