Preoperative concentrations of suPAR and MBL proteins are associated with the development of pneumonia after elective surgery for colorectal cancer.

BACKGROUND: The urokinase-type plasminogen activation (uPA) system and the mannan-binding lectin (MBL) complement activation pathway are involved in regulation of immune responses. The blood concentrations of these molecules in the individual patient thus could be related to the risk of postoperative infectious complications. The aim of this retrospective study was to determine the association between the soluble uPA receptor (suPAR) and MBL concentrations and the development of postoperative bacterial infectious complications. METHODS: Blood samples were drawn preoperatively from 544 patients scheduled to undergo primary resection for colorectal cancer. Plasma suPAR was determined by enzyme-linked immunosorbent assay and serum MBL by time-resolved immunofluorescent assay. The following infectious events were recorded during the first month after surgery: surgical site or perineal infection or both, intra-abdominal abscess, anastomotic leakage, pneumonia, and blood stream infection. Data on perioperative blood transfusions in addition to clinical baseline characteristics were included as well. RESULTS: The numbers of surgical site infections, intra-abdominal abscesses, anastomotic leakages, pneumonias, and blood stream infections were 51, 20, 32, 78, and 19, respectively. Univariate analysis showed that elevated concentrations of suPAR (p = 0.01; odds ratio [OR] 2.2; 95% confidence interval [CI] 1.2, 3.9), low concentrations of MBL (p = 0.047; OR 0.9; 95% CI 0.8, 1.0), and perioperative blood transfusion (p = 0.006; OR 1.5; 95% CI 1.1, 2.0) were associated with the development of pneumonia. Significant associations with other bacterial infections could not be demonstrated. Multivariate analysis including disease stage, sex, and age showed that suPAR, MBL, and perioperative blood transfusion were significantly and independently associated with postoperative pneumonia. CONCLUSION: Concentrations of suPAR and MBL, in addition to perioperative blood transfusion, were significantly associated with the development of postoperative pneumonia. No other statistically significant relationships could be demonstrated. Thus, further research should be directed to clarifying the biological role of these two molecules in the development of postoperative pneumonia.