New Study Reveals How GDF15 Protects the Liver in MASH, Independent of Weight Loss
New Study Reveals How GDF15 Protects the Liver in MASH, Independent of Weight Loss
A study published online this month in Cell Metabolism has identified a previously unrecognized way that the hormone GDF15 protects the liver from inflammation and fibrosis in metabolic dysfunction-associated steatohepatitis (MASH), one that has nothing to do with weight loss. The researchers, led by Dongdong Wang and Gregory Steinberg at McMaster University, in collaboration with Novo Nordisk, found that GDF15 acts through a brain-liver signaling circuit involving the body's stress hormone system, offering a mechanistic explanation that could inform the next generation of MASH therapies.
Why It Matters
GDF15 has puzzled researchers for years. Blood levels of the hormone are consistently elevated in people with MASH, and levels track with how severe the liver disease is. But it was never clear whether GDF15 was a helpful signal the body produces to fight back against liver injury, a passive marker of cellular stress, or possibly even a contributor to the damage itself. Answering that question matters directly for drug development, since GDF15-mimicking compounds (working through the same GFRAL receptor pathway used by newer anti-obesity therapies) are already being explored as treatments for obesity and metabolic disease.
Complicating earlier research further, nearly all prior animal studies of GDF15 in liver disease were conducted in mice housed at standard room temperature, a condition known to impose chronic cold stress that independently suppresses inflammation and alters metabolism. That made it difficult to know whether GDF15's apparent benefits in past studies were real, or partly an artifact of how the mice were housed.
What the Researchers Did
To get a clearer answer, the team used a newer mouse model housed at thermoneutral temperature (avoiding the cold-stress confound) and fed a diet designed to closely replicate the histological and transcriptional features of human MASH. They then took a three-part approach: first, studying mice that genetically lacked either GDF15 or its receptor GFRAL; second, treating mice with recombinant GDF15 and comparing the results against a caloric-restriction group matched for identical reductions in food intake and body weight; and third, using detailed molecular tools, including spatial transcriptomics and plasma proteomics, to work out the mechanism.
Key Findings
- Loss of GDF15 or GFRAL worsened liver inflammation and fibrosis, even though steatosis (fat buildup) and insulin resistance were no different from normal mice. The damage tracked with inflammation specifically, not simply with more fat in the liver.
- Recombinant GDF15 outperformed matched caloric restriction. Despite mice in both groups losing identical amounts of weight and eating identical amounts of food, only the GDF15-treated group showed reduced liver inflammation and fibrosis.
- The mechanism runs through the brain's stress axis. GDF15 activated the hypothalamic-pituitary-adrenal (HPA) axis, raising circulating corticosterone and increasing glucocorticoid receptor signaling in the liver. Blocking this signaling erased GDF15's anti-inflammatory effects.
- GDF15 reprogrammed liver immune cells, reducing pro-inflammatory macrophages, antibody-producing plasma B cells, and activated fibrosis-driving stellate cells, while shifting resident liver macrophages toward a calmer, lipid-handling state.
- The effect required GFRAL but not adrenaline-related signaling, pointing specifically to the HPA-glucocorticoid pathway rather than the sympathetic nervous system.
A Signal Backed by Human Data
The researchers also looked for supporting evidence in humans. People carrying a rare loss-of-function GDF15 gene variant had higher liver enzyme levels (AST) than the general population, consistent with the idea that low GDF15 leaves the liver more vulnerable. Separately, a Mendelian randomization analysis using genetic data linked higher natural GDF15 levels to a trend toward lower rates of liver fibrosis and cirrhosis.
Both human findings support the animal data, though the authors are careful to note the human analyses were limited in statistical power.
What We Still Don't Know
This is preclinical, mechanistic research, not a clinical trial, and the authors are direct about its limits. The work was conducted exclusively in male mice; whether the same GDF15-GFRAL-HPA pathway operates the same way in females remains untested. The exact neural circuitry connecting GFRAL activation in the brainstem to downstream glucocorticoid release also hasn't been mapped in detail. And while the human genetic data are supportive, they fall well short of proof; larger cohorts with biopsy-confirmed MASH will be needed to establish how relevant this pathway is in real patients.
Bottom Line for Practice
There's no direct clinical action to take from this study today, but it's worth watching. It offers the clearest mechanistic case yet that GDF15 is a genuinely protective signal in liver disease, not just a biomarker of how sick the liver is, and it does so through a completely different pathway than the appetite and weight effects that have driven interest in GDF15-based drugs so far. For clinicians tracking the MASH treatment pipeline, this strengthens the rationale for GDF15-GFRAL-targeted therapies as a potential complement to existing approaches that work primarily by reducing liver fat.
Source:
Wang D, Jabile MJT, Di Pastena F, et al. GDF15 suppresses liver inflammation independently of weight loss through neuroendocrine glucocorticoid signaling. Cell Metab. 2026;38:1-15.
