BIONEWS
Antiretroviral therapy can push HIV to undetectable. It cannot rebuild the gut lining the virus tears apart. A Nature Microbiology paper this week points to a second axis of care: a single lipid from a common gut bacterium that, in a monkey model of HIV, switched on the body's own barrier-repair program and improved antiretroviral effect in the same animals.
About 40.9 million people are living with HIV worldwide, with roughly 1.2 million new infections and around 570,000 AIDS-related deaths in 2025, according to figures cited in the trade summary of the new work. The gut is where HIV does much of its early damage: gut-associated lymphoid tissue is an early viral target, and the resulting injury produces inflamed tissue, weakened defense, and disrupted mitochondrial function that current drugs do not repair. Satya Dandekar, a professor of medical microbiology and immunology at UC Davis Health who led the new work, has spent years on that gap.
The molecule is 10-hydroxystearic acid, a fatty substance made by Lactiplantibacillus plantarum, a bacterium found in the human gut, in over-the-counter probiotics, and in fermented foods such as kimchi and sauerkraut. L. plantarum is one of the most common lactic-acid bacteria in the human gut and one of the most studied probiotic species, which gave the team a large metabolite library to work from. Among the hundreds of metabolites L. plantarum produces, 10-HSA was the strongest gut-barrier-repair candidate when the team screened them in the virally inflamed gut environment of a nonhuman primate model of HIV/AIDS.
The mechanism runs through a host nuclear receptor called PPAR-alpha, a protein that senses lipids and turns on the genes for fat metabolism. The team confirmed the binding by X-ray crystallography, the technique that produces an atomic-resolution picture of a protein and the molecule it grips. PPAR-alpha is the molecular target of an existing class of drugs, the fibrates, that doctors already prescribe for lipid disorders, which means the receptor's biology is well-mapped. Once 10-HSA engaged PPAR-alpha, three linked changes followed in gut tissue: a shift in lipid metabolism, regeneration of the mitochondria that power cells, and crotonylation, a chemical mark cells place on histones, the spools around which DNA is wound, to switch repair genes on. Together those changes rebuilt the gut epithelium, the single-cell layer that decides what the body absorbs and what it keeps out, and dialed down the inflammation behind the so-called leaky gut seen in people on long-term therapy. Barrier repair and stronger antiretroviral effect showed up in the same animals.
The result splits HIV care into two axes. One is viral suppression, which antiretrovirals already handle. The other is tissue repair, which they do not. A patient on suppressive therapy can still carry inflamed, leaky gut tissue even when blood tests show no virus, and that persistent damage is the field's emerging frontier. PPAR-alpha is the kind of receptor small molecules can already be designed to engage, so a microbial lipid that turns it on gives the repair side of HIV care a concrete starting point.
The result is in a nonhuman primate model of HIV/AIDS, not a human trial, and primate data is a long way from a prescribing decision. The field's track record with microbial-metabolite adjuncts is mixed, and several candidates that rebuilt tissue in animals have not moved the needle in people. A monkey gut is not a human gut, and a single lipid at one dose is not yet a therapy. Human trials would need to show that 10-HSA, or a drug designed to engage PPAR-alpha the same way, both reaches the gut at useful concentrations and improves clinical outcomes on top of standard antiretrovirals. Until then, 10-HSA is a candidate lead compound, not a treatment.
Gut repair is a new avenue for more durable HIV control rather than a replacement for current therapy, said Dandekar in the UC Davis Health release. The next experiments to watch are dose-finding work in primates, pharmacokinetic studies that test whether 10-HSA reaches the gut at useful concentrations in people, and the first PPAR-alpha agonists tested in HIV-positive patients on suppressive therapy. For now, HIV's hidden damage, the part antiretrovirals never touched, has a candidate repair handle for the first time.