Abstract:

Objective To investigate the role of Toll-like receptor（TLR）9 expression on the membrane surface of red blood cell（RBC） in sepsis patients with anemia. Methods A total of 237 sepsis patients（sepsis group），241 patients with local infections（local infection group） and 206 healthy subjects（healthy control group） at West China Hospital of Sichuan University from July 2022 to May 2023 were enrolled. The clinical data and 19 RBC-related parameters within 24 h of sepsis diagnosis were collected. The expressions of TLR9 on peripheral blood RBC membrane surface in 46 sepsis patients，35 common infection patients and 28 healthy subjects were determined simultaneously. The correlation between TLR9 and RBC-related parameters was assessed using Spearman analysis. Results The sepsis group had lower levels of RBC count，hemoglobin（Hb），mean corpuscular hemoglobin concentration（MCHC），the absolute value of reticulocyte（RET#），reticulocyte-hemoblobin（RET-He），red blood cell-O（RBC-O） and reticulocyte-Y（RET-Y） compared to local infection group（P<0.05）. The sepsis group had higher levels of mean corpuscular volume（MCV），red blood cell volume distribution width-standard deviation（RDW-SD），red blood cell volume distribution width-coefficient of variation（RDW-CV） and high fluorescence ratio（HFR） compared to local infection group（P<0.05）. The percentage of TLR9⁺ RBC in peripheral blood of sepsis group was higher than that in local infection group（P<0.01）. The percentage of TLR9⁺ RBC was negatively correlated with RBC count，Hb，RET#，RBC-O，MCHC，RET-He and RET-Y（P<0.01）. The percentage of TLR9⁺ RBC was positively correlated with RDW-SD and RDW-CV（P<0.001）. Conclusions The expression of TLR9 in RBC membrane surface of sepsis patients is increased，and the high expression of TLR9 is related to the degree of severe inflammatory anemia，low RBC hematopoietic ability and greater RBC morphological abnormality.

Key words: Toll-like receptor 9, Red blood cell-related parameter, Sepsis, Anemia