High molecular/low acetylated chitosans reduce adhesion of Campylobacter jejuni to host cells by blocking JlpA

Area of Science:

• Food microbiology
• Biomaterials science
• Infectious disease research

Background:

• Campylobacter spp. infections cause severe enteritis globally, necessitating effective prevention strategies.
• Antiadhesive approaches targeting early host-pathogen interactions offer a promising method to reduce bacterial load.
• Chitosan, a biopolymer, is explored for its potential antimicrobial and antiadhesive properties.

Purpose of the Study:

• To evaluate the antiadhesive and anti-invasive potential of specific chitosans against Campylobacter jejuni.
• To identify the molecular targets of chitosan's inhibitory effects on C. jejuni.
• To assess the efficacy of chitosan in reducing C. jejuni contamination in food products.

Main Methods:

• An in vitro flow cytometric adhesion assay using Caco-2 cells and C. jejuni.
• Confocal laser scanning microscopy to visualize antiadhesive and anti-invasive effects.
• Expression of C. jejuni adhesins (FlpA, JlpA) in E. coli to study chitosan's binding inhibition to fibronectin and HSP90α.
• Inoculation and treatment of chicken meat with chitosan, followed by bacterial load quantification.
• Atomic force microscopy to observe morphological changes in C. jejuni after chitosan treatment.

Main Results:

• Chitosans with high degree of polymerization and low degree of acetylation significantly reduced C. jejuni adhesion to Caco-2 cells at non-toxic concentrations.
• Chitosan demonstrated both antiadhesive and anti-invasive effects on C. jejuni.
• Chitosan specifically inhibited the binding of C. jejuni adhesin JlpA to HSP90α, but not FlpA to fibronectin.
• Treatment of chicken meat with chitosan resulted in a significant reduction of C. jejuni load.
• Atomic force microscopy revealed morphological alterations in C. jejuni cell walls upon chitosan treatment, suggesting disruption of cell wall formation via electrostatic interactions.

Conclusions:

• High molecular weight, de-acetylated chitosans show significant promise as antiadhesive and anti-invasive agents against Campylobacter jejuni.
• Chitosan's mechanism involves targeting the JlpA-HSP90α interaction and potentially disrupting bacterial cell wall integrity.
• Chitosan application presents a viable strategy for reducing C. jejuni contamination in livestock and food production, enhancing food safety.