Intermittent Fasting Promotes Bacterial Clearance and Intestinal IgA Production in Salmonella typhimurium‐Infected Mice
The effects of intermittent fasting on bacterial clearance and intestinal IgA production in Salmonella infected mice.
The impact of intermittent fasting versus ad libitum feeding during Salmonella typhimurium infection was evaluated in terms of duodenum IgA levels, bacterial clearance and intestinal and extra-intestinal infection susceptibility. Mice that were intermittently fasted for 12 weeks or fed ad libitum were infected with S. typhimurium and assessed at 7 and 14 days post-infection. Next, we evaluated bacterial load in the faeces, Peyer’s patches, spleen and liver by plate counting, as well as total and specific intestinal IgA and plasmatic corticosterone levels (by immunoenzymatic assay) and lamina propria IgA levels in plasma cells (by cytofluorometry). Polymeric immunoglobulin receptor, a- and J-chains, Pax-5 factor, pro-inflammatory cytokine (tumour necrosis factor-a and interferon-c) and anti-inflammatory cytokine (transforming growth factor-b) mRNA levels were assessed in mucosal and liver samples (by real-time PCR). Compared with the infected ad libitum mice, the intermittently fasted infected animals had (1) lower intestinal and systemic bacterial loads; (2) higher SIgA and IgA plasma cell levels; (3) higher mRNA expression of most intestinal parameters; and (4) increased or decreased corticosterone levels on day 7 and 14 post-infection, respectively. No contribution of liver IgA was observed at the intestinal level. Apparently, the changes following metabolic stress induced by intermittent fasting during food deprivation days increased the resistance to S. typhimurium infection by triggering intestinal IgA production and presumably, pathogen elimination by phagocytic inflammatory cells.
In conclusion, metabolic stress caused by intermittent fasting during food deprivation favoured bacterial clearance at the intestinal level and was associated with increased intestinal IgA and bacterial resistance at the systemic level, presumably due to the increased IgA and inflammatory responses. Intermittent fasting up- and down regulated corticosterone levels, which may influence the production of IgA necessary for bacterial eradication.