Inflammatory protein TNF-α blocks new brain cell growth

In the hippocampus (a brain region essential for memory and learning) new neurons are produced throughout life. This process is known as adult hippocampal neurogenesis. It slows down with aging and in neurodegenerative conditions, but the precise mechanisms were unclear. New research now offers part of the answer.

An inflammatory protein triggers a chain reaction

Researchers used a human hippocampal stem cell model combined with single-cell RNA sequencing and functional immune cell assays. They found that the inflammatory protein TNF-alpha triggers a type I interferon response in hippocampal progenitor cells, the cells from which new neurons develop.

That interferon response then recruits T-cells (a type of immune cell) via a signalling route involving the receptor CXCR3. This influx of T-cells causes the progenitor cells to switch function: instead of generating new neurons, they adopt an immune-defensive role. According to the researchers, this suppresses neurogenesis in a structural, not transient, way.

Possible therapeutic targets

The study, published in Nature Communications, used cells derived exclusively from female donors. Whether these findings apply to male cells, and certainly to living brains, remains unknown. The researchers stress that this is a laboratory model.

Even so, the findings are relevant from a broader longevity perspective. The aging brain displays persistent, low-grade inflammation. If that inflammation systematically suppresses neurogenesis via TNF-alpha, it could help explain cognitive decline in later life. The CXCR3 pathway involved is known from other conditions and represents a potential therapeutic target, though that remains speculative at this stage.

The study does not show whether blocking TNF-alpha or CXCR3 actually restores neurogenesis. That requires follow-up work in animal models and ultimately in humans.

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