Investigating the Impact of Fusobacterium nucleatum on Oxidative Stress, Chemoresistance, and Inflammation in Inflammatory Bowel Disease and Colorectal Cancer: Rationale and Design of a Clinical Trial

Abstract

Fusobacterium nucleatum (F. nucleatum), a Gram-negative anaerobe, is increasingly implicated in the pathogenesis of colorectal cancer (CRC) and inflammatory bowel disease (IBD). Its adhesin FadA enables epithelial adherence and invasion, promoting inflammation and tumorigenesis. F. nucleatum has been shown to activate the NLRP3 inflammasome, leading to IL-1β release, and is associated with chemoresistance and poor prognosis in CRC. Additionally, lipid peroxidation markers such as malondialdehyde (MDA) and 4-hydroxy-nonenal (4-HNA) may contribute to inflammation-driven carcinogenesis. This study protocol aims to investigate the role of F. nucleatum in the development and progression of IBD and CRC through integrated clinical, molecular, and imaging approaches. The protocol involves quantifying F. nucleatum in tissue biopsies across disease stages and assessing correlations with inflammatory and oxidative markers. It will explore the bacterium's involvement in NLRP3 inflammasome activation, IL-1β production, and autophagy, and its potential contribution to chemoresistance. Furthermore, radiomic analysis of computed tomography (CT) images will be performed to identify imaging phenotypes associated with microbial load and inflammatory activity. Although primarily a protocol, the study includes preliminary in vitro data showing that exposure to FadA significantly increases inflammatory markers in Caco-2 cells, supporting the hypothesis that F. nucleatum contributes to a pro-inflammatory, pro-tumorigenic microenvironment relevant to CRC progression.

Keywords: CRC; IBD; NOS; ROS; autophagy; cancer cell death; chemoresistance; host immune responses; lipid peroxidation; microbiota; oxidative stress; prognostic factor.

Figure 1

Key role of F. nucleatum in colon cancer progression, metastasis, and chemoresistance. In brief, F. nucleatum can change the colon cancer microenvironment in a pro-inflammatory fashion with a switch Th1–Th17 phenotype. F. nucleatum, through its FadA and lipopolysaccharide (LPS), increases β-catenin, miR-21, and oxidative stress in colon cancer cells. Moreover, this interaction leads to an increase in epithelial–mesenchymal transition, to a greater predisposition to DNA damage and secretion of cytokines and growth factors with anti-apoptotic and pro-metastatic potential.

Figure 2

Intracellular levels of NLRP3 (A) and MyD88 (B), and secreted IL-6 (C) and IL-8 (D) in Caco-2 cells following FadA and LPS stimulation. Data are expressed as mean ± standard error (SE) from at least three independent experiments. Statistical significance: ns = not significant, p < 0.05, p < 0.01, p < 0.001 (ANOVA, post hoc Tukey’s test).