[The role of transferrin receptor CD71 as a diagnostic and prognostic biomarker in sepsis].

To find new biomarkers for the diagnosis and prognosis of sepsis through analyzing the differential expression protein in sepsis by proteomics and bioinformatics analysis and enzyme linked immunosorbent assay (ELISA).Patients with sepsis admitted to the emergency department of the Affiliated Hospital of Southwest Medical University from January to December 2019 were enrolled. And meanwhile, healthy volunteers who had normal physical examinations were included as the control group. Blood samples from two groups were collected. The samples were randomly selected for the protein concentration by data independent acquisition (DIA). Bioinformatics method was used in differentially expressed proteins by gene ontology (GO) pathway, enrichment analyses, groups meta-analysis and survival curves construction. ELISA method was used to verified marker screened. Then the data of transferrin receptor CD71 and the clinical data of procalcitonin (PCT), C-reactive protein (CRP) and blood lactic acid (Lac) were collected to construct receiver operator characteristic curve (ROC curve), and biomarker was screened for diagnostic and prognostic of sepsis.The result of DIA showed that 71 differentially expressed proteins were screened out from sepsis group, 6 proteins were down-regulated and 65 proteins were up-regulated. Those differentially expressed proteins were enriched in the inflammatory response, response to stress, leukocyte migration in the GO pathway and enrichment analyses. The meta-analysis showed that the expression level of CD71 was higher in sepsis group than normal control group [standardized mean difference (SMD) = -0.47, 95% confidence interval (95%CI) was -0.93 to 0.00, P < 0.01], the expression level of CD71 was higher in non-survivor group than survivor group (SMD = -0.44, 95%CI was -0.70 to -0.18, P = 0.63). Survival curve showed that the expression of CD71 was inversely correlated to survival rates, the patients with a lower expression had higher survival rates (P = 0.000 34); the ELISA showed that the level of CD71 was higher in sepsis group than normal control group (nmol/L: 156.83±84.71 vs. 87.99±47.89, P < 0.05), the level of CD71 was higher in non-survivor group than survivor group (nmol/L: 219.63±125.59 vs. 130.97±40.45, P < 0.05). The area under the ROC curve (AUC) of CD71 in diagnostic performance of sepsis was 0.790 (sensitivity was 65.1%, specificity was 90.0%), the AUC of CD71 in prognostic performance of sepsis was 0.744 (sensitivity was 57.1%, specificity was 94.1%); CD71 had a better prognostic performance than PCT (AUC = 0.547, sensitivity was 64.3%, specificity was 55.9%), CRP (AUC = 0.594, sensitivity was 64.3%, specificity was 61.8%), Lac (AUC = 0.540, sensitivity was 42.9%, specificity was 82.4%).CD71 had a great value of diagnostic and prognostic performance in sepsis, and it was expected to be a potential biomarker for sepsis.