INTRO: Clusterin (Apolipoprotein J) is a 70-80kDa glycoprotein that is widely distributed in physiologic fluids such as plasma. It has been described as a circulating stress-induced cyto-protective chaperone; it acts by scavenging toxic lipid byproducts and inhibiting complement mediated cytolysis; the latter occurs in a dose dependent manner by binding to nascent C5b-9 thus preventing formation of the membrane attack complex (MAC). Major open and, to a lesser extent, minimally invasive surgery have been associated with transient post-operative immune-suppression. This study's aim was to further study the immune-regulatory effects of minimally invasive colorectal surgery, as reflected by changes, if any, in plasma levels of Clusterin.
Methods: A total of 35 patients (pts) undergoing minimally invasive resection (MIR) either for benign (n= 17) or malignant pathology (n=18) were studied. The groups were similar in regards to mean age (cancer pts, 68.5; benign pts, 55.8), male to female ratio (2:1 in both populations), operation performed, and complications. The mean incision size was 5.2 cm (range 3.5 to 13) for the benign pts and 5.4 cm (range 3.0 to 10.5) for the cancer pts. Plasma samples were obtained preoperatively (PO) and on post-operative days (POD) 1 and 3. Plasma Clusterin levels were assessed in duplicates via ELISA. The Wilcoxon signed rank test and Mann Whitney U test were used, where appropriate, to determine statistical significance (P < 0.05).
Results: The mean PO Clusterin levels were comparable between the 2 groups. In the benign pts, the PO plasma concentration of Clusterin was 83.83ng/ml ± 26.19; on POD1 the levels decreased to 63.21ng/ml ± 19.19 (p = 0.0068) and on POD3 further decreased to 53.63ng/ml ± 25.06 (p = 0.0088). However in the cancer group no significant change in Clusterin levels was noted post-op; the PO Clusterin level was 78.48ng/ml ± 35.46 whereas the POD 1 mean value was 67.07ng/ml ± 36.28 and the POD 3 result was 67.64 ± 39.45.(p-values 0.1051 and 0.1738, respectively).
Conclusion: A significant decrease in Clusterin levels early in the post-operative period was noted in pts undergoing MIR for benign pathology. It is unclear why this alteration was not observed in the cancer population. This phenomenon might be related to surgery-related immune suppression. Further research is warranted to determine the mechanism of and the clinical relevance, if any, of the plasma Clusterin decrease post benign surgery.