Impact of Dietary Fiber on West Nile Virus Infection.

Duan Ni,Alanna Gabrielle Spiteri,Dragana Stanley,Jian Tan,Laurence Macia,Paula Niewold,Gabriela Veronica Pinget,Nicholas Jonathan Cole King

doi:10.3389/fimmu.2022.784486

Abstract

Dietary fiber supports healthy gut bacteria and their production of short-chain fatty acids (SCFA), which promote anti-inflammatory cell development, in particular, regulatory T cells. It is thus beneficial in many diseases, including influenza infection. While disruption of the gut microbiota by antibiotic treatment aggravates West Nile Virus (WNV) disease, whether dietary fiber is beneficial is unknown. WNV is a widely-distributed neurotropic flavivirus that recruits inflammatory monocytes into the brain, causing life-threatening encephalitis. To investigate the impact of dietary fiber on WNV encephalitis, mice were fed on diets deficient or enriched with dietary fiber for two weeks prior to inoculation with WNV. To induce encephalitis, mice were inoculated intranasally with WNV and maintained on these diets. Despite increased fecal SCFA acetate and changes in gut microbiota composition, dietary fiber did not affect clinical scores, leukocyte infiltration into the brain, or survival. After the brain, highest virus loads were measured in the colon in neurons of the submucosal and myenteric plexuses. Associated with this, there was disrupted gut homeostasis, with shorter colon length and higher local inflammatory cytokine levels, which were not affected by dietary fiber. Thus, fiber supplementation is not effective in WNV encephalitis.

Highlights

Consumption of dietary fiber confers health benefits and correlates with decreased mortality from both infectious and non-infectious diseases [1]
Dietary fiber and short-chain fatty acids (SCFA) are beneficial in infectious diseases with decreased mortality in a mouse model of influenza infection [8] and of Citrobacter rodentium infection [9]
To determine whether beneficial reshaping of the gut microbiota could affect the severity of WNV infection, mice were fed on diets enriched in dietary fiber or deficient in dietary fiber for 2 weeks prior to infection (Figure 1A)

Summary

Introduction

Consumption of dietary fiber confers health benefits and correlates with decreased mortality from both infectious and non-infectious diseases [1]. Dietary fiber comprises non-digestible complex carbohydrates that promote gut health through the beneficial reshaping of the gut microbiota. This occurs through the release of bacterial metabolites, short-chain fatty acids (SCFA), during its fermentation in the colon [2]. The benefits of dietary fiber and SCFA extend beyond the gastrointestinal tract, influencing immune responses in the lungs in a model of allergic airway inflammation [5], in the pancreas in a model of type 1 diabetes [6] or in the brain in multiple. Dietary fiber and SCFA are beneficial in infectious diseases with decreased mortality in a mouse model of influenza infection [8] and of Citrobacter rodentium infection [9]

Methods

Results

Conclusion