Limited TB protection after time-restricted feeding despite fewer CD4 + T cells
Ranjan Kumar Nanda reports that pre-exposure time-restricted feeding reduced tissue CD4 + T cells but had limited effect on early Mycobacterium tuberculosis clearance.
Tuberculosis remains a global health challenge, and scientists are exploring how diet and metabolism influence the immune system's ability to fight infection. In new research led by Ranjan Kumar Nanda, investigators tested whether a short daily eating window known as time-restricted feeding (TRF) would change how mice respond to Mycobacterium tuberculosis. The team used male C57BL/6 mice (6–8 weeks old) and put them on an 8-hour dark-phase TRF schedule for 30 days. After that pre-exposure period the animals were aerosol infected with a low dose (100-400 colony-forming units) of Mycobacterium tuberculosis (Mtb) H37Rv. Over the course of the experiment the researchers tracked body weight gain, glucose handling, and changes across multiple tissues using metabolome and proteome analysis, and also measured the distribution of immune cells in organs such as the lung, spleen, liver and bone marrow. The study asked two main questions: does TRF change metabolism in ways that matter for infection, and does it alter immune cell numbers or the early ability to clear Mtb?
The researchers observed that during the first 15 days of TRF the mice showed better glucose tolerance and only marginal weight loss, indicating an improved metabolic phenotype. Detailed analyses of the serum and liver metabolome revealed perturbations in fatty acid biosynthesis and degradation, steroid hormone biosynthesis pathways, and tyrosine metabolism. Liver proteome data pointed to increased fatty acid oxidation, a change the authors suggest could influence the frequency and function of immune cells. To test infection outcomes, TRF and control mice were compared at 21 days post-infection. Tissue bacterial burden in lung, spleen and liver was similar between the two groups, indicating limited impact of the TRF regimen on early Mtb clearance. However, immune profiling showed differences: the bone marrow of Mtb-infected TRF mice had significantly lower CD3 + T cells, and CD4 + T cells were reduced both in the bone marrow and in the lungs. These cellular changes occurred despite metabolic benefits from TRF.
Taken together, the findings suggest a complex picture: pre-exposure to an 8-hour dark-phase TRF schedule produced clear metabolic shifts and improved glucose control, but those changes did not translate into improved early control of Mycobacterium tuberculosis infection. The observed reductions in CD3 + and CD4 + T cells in bone marrow and lung raise the possibility that altered lipid metabolism and increased fatty acid oxidation in the liver may influence immune cell numbers or trafficking during infection. The study also notes that discontinuing TRF curtails its potential positive effects on handling Mtb at this early time point, implying timing and duration of dietary interventions matter. While this work does not show a protective effect of short-term TRF against early Mtb growth, it highlights the need for further research to determine whether different TRF schedules, sustained feeding changes, or longer follow-up would yield different effects on immunity and bacterial clearance.
This work suggests that short-term time-restricted feeding changes metabolism but may not help clear early tuberculosis infection and can reduce key T cells. Clinicians and researchers should be cautious about assuming dietary timing boosts early immune defense against Mtb without further evidence.
Author: Ashish Gupta