Why immune aging weakens tuberculosis defenses in older populations

TB research has systematically sidelined what happens in aging organisms, leaving a pressing clinical question unanswered: why do adults over 60 show TB incidence 2–3 times higher, with mortality up to 4 times greater? New research in mice across age groups reveals the mechanism. Although young (2–4 months), old (17–19 months), and very old (31 months) mice showed similar bacterial loads in lung, spleen, and liver for the first 6 weeks post-infection, older animals exhibited markedly slower TB clearance two weeks after rifampicin and isoniazid treatment. Proteomic analysis identified the culprit: aged CD4+ T cells bearing severe mitochondrial dysfunction, marked by deregulation of proteins essential for cellular energy production. This immunometabolic failure is not merely a sign of aging, but a concrete therapeutic obstacle that slows bacterial elimination when it matters most—during treatment. For older populations, this opens a clear pathway: restoring immune mitochondrial function could become the complement traditional antibiotics need.