Effect of dexmedetomidine on postoperative cognitive dysfunction and the T helper 17/regulatory T cell balance in...

To investigate the effect of dexmedetomidine (DEX) on alleviating postoperative cognitive dysfunction (POCD) and T helper 17 (Th17)/regulatory T cell (Treg) imbalance in geriatric patients undergoing orthopedic surgery.

A total of 82 geriatric patients undergoing lower extremity joint replacement surgery were enrolled and randomized into two groups. Patients in the experimental group received a loading dose of 0.5 µg/kg DEX for 10 min and then a maintenance dose of 0.5 µg/kg/h DEX until 30 min before the end of the surgery, while patients in the control group were administered with an equal volume of saline. The mini-mental state examination (MMSE) was used to evaluate the patients' cognitive function levels. The enzyme-linked immunosorbent assay (ELISA) was used to detect the protein levels of S100 calcium-binding protein B (S-100β), matrix metalloproteinase 9 (MMP9), interleukin-10 (IL-10) and interleukin-17A (IL-17A). The quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect and compare the mRNA levels of retinoic acid-related orphan receptor gamma-t (RORγt) and forkhead box P3 (Foxp3), the ratio of which reflected Th17/Treg balance.

Compared to the control group, the MMSE scores in the DEX group were obviously higher at 24 and 72 h after the surgery, and the incidence of POCD was lower in the DEX group. Simultaneously, DEX significantly decreased the level of S100β, MMP9, and the ratio of RORγt/Foxp3 mRNA at the end of the surgery and one day after surgery. Furthermore, IL-10 was upregulated, while the IL-17A and the IL-17A/IL-10 ratio were downregulated at the end of the surgery and one day after surgery in the DEX group.

DEX could reduce the incidence of POCD in elderly orthopedic patients, which might be related to the attenuation of inflammatory response and blood-brain barrier (BBB) damage through modulating the Th17/Treg imbalance.