MASH

Spotlight article

Myeloid S1P1 Deletion Reduces Inflammation and Fibrosis in MASH Without Altering Steatosis

Metabolic dysfunction-associated steatohepatitis (MASH) is driven by immune-mediated hepatic inflammation, triggered in part by lipid dysregulation, especially elevated palmitic acid, which activates the sphingolipid pathway and raises sphingosine 1-phosphate (S1P) levels. S1P acts through five G-protein-coupled receptors to promote proinflammatory responses. Previous studies showed that pharmacologic S1P inhibition reduces liver inflammation. This study used a myeloid cell–specific S1P1 knockout mouse model (S1pr1MKO) to clarify S1P1’s role in MASH. Despite similar steatosis and body mass, S1pr1MKO mice on a high-fat, high-fructose, high-cholesterol diet exhibited significantly less liver inflammation, injury, and fibrosis compared to wild-type controls.

 

S1P1 deletion in myeloid cells reduced hepatic accumulation of pro-inflammatory monocyte-derived macrophages, increased restorative resident macrophages, and suppressed inflammatory gene expression. Mass cytometry and transcriptomics confirmed enhanced apoptosis in S1P1-deficient macrophages, suggesting impaired survival as a key mechanism. Unlike prior studies using non-specific S1P inhibitors, this targeted approach isolates myeloid S1P1 as a critical driver of MASH inflammation. These findings support macrophage-specific S1P1 as a therapeutic target for reducing liver injury and fibrosis in MASH without altering steatosis.

 

Reference: Parthasarathy G, Venkatesan N, Sidhu GS, et al. Deletion of sphingosine 1-phosphate receptor 1 in myeloid cells reduces hepatic inflammatory macrophages and attenuates MASH. Hepatol Commun. 2025 Feb 3;9(2):e0613. doi: 10.1097/HC9.0000000000000613. PMID: 39899672.

Corrie Berk

DNP, MBA, APRN

Nurse Practitioner, Texas Liver Institute

Featured article

Bariatric Surgery Lowers Mortality and Heart Risk in MASLD Better Than Medications

A recent multicenter study of more than 8,600 patients with metabolic dysfunction-associated steatotic liver disease (MASLD) found that bariatric surgery is associated with lower five-year mortality. It also showed a reduced risk of major adverse cardiovascular events (MACEs) compared to treatment with GLP-1 receptor agonists, SGLT2 inhibitors, or a combination of both medications and surgery. Patients who underwent bariatric surgery alone had better long-term survival and cardiovascular outcomes, with adjusted hazard ratios indicating higher risks for those treated pharmacologically. Researchers presented the findings at The Liver Meeting 2024, underscoring the need for personalized treatment decisions based on individual health profiles and goals.

 

While weight loss medications offer notable metabolic benefits, the study suggests bariatric surgery may provide more robust and sustained improvements in weight and cardiovascular health for certain patients with MASLD. However, both researchers and external experts cautioned that surgery isn’t suitable for all patients, and outcomes can vary based on factors like comorbidities, BMI, glucose control, and patient preferences. The findings highlight the importance of a multidisciplinary approach in MASLD treatment and call for further randomized trials to better understand which patients benefit most from surgical versus pharmacologic interventions.

 

Reference: Crist C. Bariatric Surgery Better Than Obesity Drugs for Some Patients With MASLD. GI and Hepatology News. Published December 12, 2024. Accessed June 9, 2025. https://www.mdedge.com/gihepnews/article/271916/liver-disease/bariatric-surgery-better-obesity-drugs-some-patients-masld

Jennifer Geremia

MSPAS, PA-C

Intermittent Fasting Is an Effective Way to Reverse Fatty Liver Disease

In an interview with the Fatty Liver Alliance, Dr. Jason Fung, a nephrologist, bestselling author, and co-founder of The Fasting Method, discussed the growing prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) and the role of diet and intermittent fasting in reversing it. He explained that fatty liver disease has surged since the 1980s due to increased sugar and carbohydrate consumption, which leads the liver to produce fat through de novo lipogenesis. This accumulation of liver fat contributes to metabolic syndrome and type 2 diabetes. Dr. Fung emphasized that reducing carbohydrate intake through approaches like the green Mediterranean diet, low-carb, or ketogenic diets, alongside intermittent fasting, can help reverse fatty liver by allowing the body to burn stored liver fat.

 

Dr. Fung advocates for intermittent fasting as a simple, accessible intervention to help people lose weight and restore metabolic health. He explained that fasting not only limits glucose intake but actively promotes fat burning, especially from the liver. While GLP-1 medications can assist with appetite suppression, he noted that focusing on diet—rather than drugs—is key for long-term health. Dr. Fung advised beginners to start with overnight fasting (12–14 hours), gradually increase to 16 hours or more, and eliminate snacking. He also acknowledged social challenges, like dining out, but encouraged flexibility and building sustainable habits.

 

Reference: Fung J, Betel M. Discusses the Benefits of Intermittent Fasting. YouTube. Published May 16, 2024. Accessed June 9, 2025. https://www.youtube.com/watch?v=tSKEkrWtF0Y

Jennifer Geremia

MSPAS, PA-C

FDA Approves Resmetirom for MASH

Resmetirom received accelerated FDA approval in March 2024 for treating metabolic dysfunction-associated steatohepatitis (MASH) with moderate to advanced fibrosis (F2-F3), based on positive outcomes from the MAESTRO-NASH and MAESTRO-NAFLD-1 trials. It showed efficacy in resolving steatohepatitis and improving fibrosis without worsening other disease markers. Because the FDA label lacks detailed clinical guidance, the AASLD issued interim recommendations based on available data. Resmetirom may be prescribed without biopsy if noninvasive assessments (NILDA), such as VCTE or MRE, suggest steatosis and fibrosis in patients with cardiometabolic risk factors.

 

Monitoring safety and efficacy is key. Liver function tests should be performed regularly, and treatment stopped if hepatotoxicity occurs. Resmetirom is generally well tolerated, though diarrhea and nausea are common. Thyroid and lipid levels should be monitored due to possible hormonal and drug interaction effects. A ≥25% reduction in VCTE or ≥20% in MRE liver stiffness, along with ALT improvement, may signal treatment response. If no improvement or worsening is seen after 12 months, clinicians should assess whether to continue based on fibrosis status, comorbidities, and treatment response. Ongoing trials will help refine these recommendations.

 

Reference: Chen VL, Morgan TR, Rotman Y, et al. Resmetirom therapy for metabolic dysfunction-associated steatotic liver disease: October 2024 updates to AASLD Practice Guidance. Hepatology. 2025 Jan 1;81(1):312-320. doi: 10.1097/HEP.0000000000001112. Epub 2024 Oct 18. Erratum in: Hepatology. 2025 Apr 1;81(4):E133. doi: 10.1097/HEP.0000000000001186. PMID: 39422487.

Corrie Berk

DNP, MBA, APRN

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