Neuron-like cells discovered inside tuberculosis granulomas

Tuberculosis (TB), caused by Mycobacterium tuberculosis, remains a major global killer and forms distinctive structures called granulomas in the lungs and other tissues. These granulomas are hubs where the bacterium and the host immune system interact, but researchers do not yet fully understand every cell type that takes part. In new work led by Olivier Neyrolles, scientists searched these structures across species and uncovered an unexpected cell population marked by β3-tubulin (TUBB3), a protein usually associated with nerve cells. The team found TUBB3+ cells within granulomas from mice, guinea pigs, non-human primates, and human TB patients. These TUBB3+ cells are not the typical pulmonary resident cells or the white blood cells usually studied in TB; instead, they have a branched, elongated appearance that looks neuron-like. Because the discovery spans multiple animal models and humans, it points to a conserved feature of granulomas rather than a quirk of a single species. The finding raises fresh questions about how the nervous system and immune system might interact inside the very structures that contain TB infection.

The core observation reported is the identification of a TUBB3-positive cell population inside tuberculosis granulomas across diverse hosts: mice, guinea pigs, non-human primates, and TB patients. TUBB3, also written as β3-tubulin, is a well-established pan-neuronal marker, yet these cells differed from known pulmonary resident cells and from leukocytes based on their morphology and location within granulomas. Morphologically, the TUBB3+ cells exhibited a branched, elongated shape that is suggestive of neuron-like features rather than conventional immune cell appearances. Importantly, the investigators noted that the appearance of these TUBB3+ cells did not require adaptive immunity, indicating they can arise independently of mature T and B cell responses. The same TUBB3+ population was also observed during some viral and fungal infections, but conspicuously absent in samples from asthma, suggesting a degree of specificity to infectious lung conditions. These consistent patterns across multiple infection types and species form the experimental backbone of the report and highlight TUBB3 as a marker worth following up in TB research.

If granulomas contain a bona fide neuro-immune element, as the presence of TUBB3+ cells suggests, this could change how scientists think about disease progression and host defense in TB. A neuro-immune component might influence inflammation, tissue remodeling, bacterial containment, or transmission in ways that classic immune-focused models have not captured. The authors emphasize that the origin, precise identity, and signaling pathways of these TUBB3+ cells remain unknown and require further study; determining whether they are resident nerve cells recruited into granulomas, a transformed immune cell type expressing neuronal markers, or a novel stromal population will be key. Understanding their function could reveal new angles for therapy or diagnostics: if these cells affect bacterial survival or tissue damage, they might become targets for interventions that modulate neuro-immune interactions rather than only targeting bacteria or conventional immune responses. In short, the discovery opens new lines of inquiry that could expand options for treating TB and other pulmonary infections where similar cells appear.