Association of circulating markers of gut barrier damage and inflammation with colorectal neoplasia stage
Abstract
A disturbance in the microbiome facilitated by gut barrier dysfunction and inflammation can influence the progression of colorectal neoplasia. One of the most studied indicators of gut barrier status is lipopolysaccharide (LPS). Increased permeability of the gut barrier leads to extensive translocation of microbes into the lamina propria, which is associated with higher circulating levels of LPS. Additionally, increased serum concentrations of inflammatory cytokines including IFNy, IL6, IL10, and TNFα have been associated with impaired gut integrity and its progressive dysfunction.
We investigated the role of gut barrier permeability and inflammation in colorectal cancer (CRC) development by assessing markers of intestinal barrier dysfunction and inflammation in two different patient cohorts; Irish (discovery) and Czech (validation). ELISA assays were used to assess circulating concentrations of lipopolysaccharide binding protein (LBP) and C-reactive protein (CRP) in serum from patients with CRC (n=30), colorectal adenoma (n=40), and negative after colonoscopy/blood donor controls (n=35). Circulating levels of inflammatory cytokines and calprotectin were assessed using an MSD MultiSPOT platform and an MSD R-plex assay (Mesocale Discovery, Rockville, Md, United States), respectively. Differences between pathology groups were assessed using the Kruskal Wallis or Mann-Whitney U test. Receiver operating curve (ROC) analysis was implemented to identify single and combinations of biomarkers capable of discriminating between CRC patients and controls with maximum sensitivity (SE) and specificity (SP) (RStudio, PBC, Boston, MA URL http://www.rstudio.com/).
In the discovery cohort, levels of LBP, TNFα, IL6, calprotectin and CRP were significantly higher in CRC patients than in controls after false discovery rate correction (p=0.02, p=0.03, p=0.006, p=0.01, p=0.006, respectively). The area under the ROC curve (AUC) was 0.76 (95% CI: 0.64-0.87, p = 0.003) for LBP, 0.69 (95% CI: 0.55-0.82, p = 0.007) for calprotectin and 0.87(95% CI: 0.74-1.00, p = 0.003) for CRP. The optimal biomarker combination for discriminating between CRC and controls was the combination of the three markers (SP= 0.75, SE = 0.75). In the validation cohort, levels of calprotectin and TNFα, were significantly higher in cancer compared to control (p=0.05, p=0.02, respectively). Furthermore, IFNγ and IL10 were also significantly elevated in cancer compared to control (p= 0.02, p=0.003, respectively). These results support the hypothesis that a dysfunctional gut barrier and attendant inflammation may influence CRC development and progression. Additionally, LBP, CRP and calprotectin may have potential as diagnostic biomarkers for CRC or for risk stratification. Gut bacterial and barrier wall modulation and stabilization has potential for preventing colorectal adenomas and hence colorectal cancer.