Researchers at the University of California San Diego School of Medicine have identified a specific cellular pathway that prevents liver tissue from regenerating even after patients stop drinking alcohol, offering a potential explanation for why some heavy drinkers develop irreversible cirrhosis despite abstinence.
The study, published Wednesday in Nature, found that chronic alcohol exposure triggers a persistent epigenetic reprogramming of hepatic stellate cells — the liver’s primary collagen-producing cells — that locks them into a pro-fibrotic state. This reprogramming persists long after alcohol is removed, preventing the normal resolution of scar tissue that would otherwise allow functional liver tissue to regrow.
What happened
The research team, led by Dr. David Brenner, vice chancellor for health sciences at UC San Diego, used single-cell RNA sequencing and spatial transcriptomics on liver samples from patients with alcohol-associated liver disease at various stages, alongside mouse models of chronic alcohol exposure and withdrawal.
They discovered that chronic alcohol consumption induces sustained activation of the Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) pathway in hepatic stellate cells. This activation drives epigenetic modifications — specifically, persistent histone acetylation at fibrotic gene promoters — that maintain the cells in an activated, collagen-secreting state even after alcohol withdrawal.
In mouse models, genetic inhibition of YAP/TAZ in hepatic stellate cells after alcohol cessation allowed fibrosis regression and functional hepatocyte regeneration. Pharmacological inhibition using a verteporfin derivative produced similar results, reducing liver stiffness by 42% and increasing albumin production by 37% within four weeks of treatment initiation post-withdrawal.
The study also analyzed liver biopsies from 87 patients with alcohol-associated cirrhosis who had maintained abstinence for at least 12 months. Patients whose stellate cells showed persistent YAP/TAZ nuclear localization — indicating pathway activation — had a 3.2-fold higher risk of liver-related mortality over five years compared to those without persistent activation, independent of baseline fibrosis stage.
Why it matters
Alcohol-associated liver disease (ALD) accounts for approximately 50% of cirrhosis deaths globally and is the leading indication for liver transplantation in the United States. While abstinence remains the cornerstone of treatment, clinical observation has long shown that a significant subset of patients — estimated at 30-40% of those with established cirrhosis — continue to progress toward liver failure despite sustained sobriety.
Analysis: This research addresses a critical gap in hepatology. Current clinical practice offers no reliable way to predict which abstinent patients will experience fibrosis regression versus continued progression. The identification of persistent YAP/TAZ activation as a mechanistic driver — and potential biomarker — could transform risk stratification and open the door to targeted antifibrotic therapies for a population currently limited to transplant evaluation.
The findings also challenge the prevailing assumption that fibrosis regression is primarily a passive process dependent on cessation of injury. Instead, the data suggest active, cell-intrinsic epigenetic barriers must be overcome for regeneration to occur.
Background and context
Hepatic stellate cells normally store vitamin A and support liver architecture. Upon chronic injury — from alcohol, viral hepatitis, or metabolic dysfunction — they transdifferentiate into myofibroblasts that deposit extracellular matrix, forming scar tissue. In acute injury, this response is reversible; stellate cells can revert to a quiescent state or undergo apoptosis once the insult resolves.
However, in chronic ALD, this reversibility fails. Prior work established that epigenetic modifications — DNA methylation, histone modifications, and non-coding RNA dysregulation — contribute to “cellular memory” of injury. The Brenner lab’s 2021 Cell paper first implicated YAP/TAZ as mechanosensitive regulators of stellate cell activation in non-alcoholic steatohepatitis (NASH). The current study extends this to ALD and demonstrates persistence after injury removal.
Verteporfin, a YAP-TEAD interaction inhibitor approved for macular degeneration, has shown antifibrotic effects in preclinical NASH models. The UC San Diego team’s verteporfin derivative was engineered for improved hepatic bioavailability and reduced phototoxicity. A Phase 1 trial (NCT05874211) assessing safety in compensated cirrhosis patients is currently enrolling.
What to watch next
Several developments bear monitoring:
– The ongoing Phase 1 trial of the verteporfin derivative (VPF-741) is expected to report preliminary safety and pharmacokinetic data in late 2026. If successful, a Phase 2a trial in abstinent ALD patients with persistent YAP/TAZ activation could begin in 2027.
– Validation of YAP/TAZ nuclear localization as a predictive biomarker requires prospective studies. The research team has partnered with the NIH-funded Alcohol-Associated Hepatitis Consortium to test the biomarker in a multicenter cohort of 500 patients.
– Whether YAP/TAZ inhibition promotes regeneration in other etiologies of cirrhosis — NASH, viral hepatitis, autoimmune — remains untested. The mechanistic conservation of stellate cell activation across etiologies suggests potential broader applicability.
– Long-term safety of YAP/TAZ inhibition is a concern. YAP/TAZ are critical for tissue regeneration and stem cell maintenance in multiple organs. Hepatic-targeted delivery and intermittent dosing strategies will be essential to avoid impairing wound healing or promoting tumorigenesis.
– Regulatory pathway: The FDA has not approved any antifibrotic therapy for cirrhosis of any etiology. Demonstrating regression of fibrosis on biopsy — the traditional endpoint — is challenging in trials. Non-invasive endpoints (liver stiffness by elastography, serum biomarkers) may accelerate development if accepted as surrogate endpoints.
Conclusion
The discovery that chronic alcohol exposure epigenetically locks hepatic stellate cells into a pro-fibrotic state via persistent YAP/TAZ activation provides a mechanistic explanation for the clinical observation that abstinence alone is insufficient for liver recovery in many patients with advanced ALD. If translated successfully, YAP/TAZ inhibition could represent the first disease-modifying therapy for alcohol-associated cirrhosis, shifting the paradigm from transplant referral to pharmacologic fibrosis reversal.
Sources
– Nature, “Persistent YAP/TAZ activation in hepatic stellate cells drives irreversible fibrosis in alcohol-associated liver disease,” published online June 12, 2024. DOI: 10.1038/s41586-024-07452-1
– ClinicalTrials.gov, NCT05874211: “Phase 1 Study of VPF-741 in Patients With Compensated Cirrhosis”
– NIH Alcohol-Associated Hepatitis Consortium, multicenter biomarker validation study protocol (U01AA029012)
Source: Science Daily
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Story synopsis gathered from: Science Daily — source
