Kohli, Rohit

Pediatric metabolic dysfunction–associated steatotic liver disease (MASLD) has become more prevalent on a global scale over the last decades and is associated with significant comorbidities in childhood and a 40-fold higher risk of early mortality in young adulthood. MASLD has now become the leading indication for liver transplantation in young adults in the United States. However, pediatric MASLD is still perceived as an indolent condition by many patients, families, and clinicians. In this Call to Action, we aim to raise awareness of pediatric MASLD as a public health crisis. Herein, we describe insufficient screening and disease staging practices, and a lack of accurate non-invasive tests and effective pharmacotherapy, both stemming from a paucity of multicenter clinical trials in pediatric MASLD. We provide clear steps to address this public health emergency by promoting awareness campaigns, educating and empowering patients and families, addressing barriers including access to care, nutritional and exercise support programs, establishing multidisciplinary care, launching community initiatives, and conducting clinical trials in pediatric MASLD for an age-based evaluation of novel diagnostic and therapeutic options. We conclude by highlighting the urgent need for comprehensive public health policies to control the tide of pediatric MASLD and call upon stakeholders to act now.

Abstract Background Prevalence of metabolic dysfunction‐associated steatotic liver disease (MASLD), previously known as nonalcoholic fatty liver disease (NAFLD), and its sequelae of more severe forms such as metabolic dysfunction‐associated steatohepatitis (MASH) is rapidly increasing in children with the rise in obesity. Successful and sustainable treatments for MASLD are lacking in children. We determined the therapeutic effect of N ‐acetyl cysteine (NAC) on biomarkers of oxidative stress, inflammation and insulin resistance (IR), liver enzymes, liver fat fraction (LFF) and liver stiffness (LS) in children with obesity and biopsy‐confirmed MASLD. Methods Thirteen children ( n = 13; age: 13.6 ± 2.8 years; NAS score >2) underwent a double‐blind, placebo‐controlled trial of NAC (either 600 or 1200 mg NAC/day) or placebo for 16 weeks. Measurements included LFF (magnetic resonance imaging), LS (ultrasound elastography), and body composition. Erythrocyte glutathione (GSH), liver enzymes, insulin, glucose, adiponectin, high‐sensitivity c‐reactive protein (hs‐CRP), and interleukin‐6 (IL‐6) were also measured. homeostasis model assessment for insulin resistance (HOMA‐IR) was calculated. Results Sixteen‐week NAC treatment improved (baseline adjusted between‐group p < .05 for all) markers of inflammation (IL‐6 and hs‐CRP), oxidative stress (GSH), and IR (HOMA‐IR) and reduced liver enzymes, LFF and LS. Body weight and body composition did not show beneficial changes. Conclusions Sixteen‐week NAC treatment was well tolerated in children with obesity and MASLD and led to improvements in oxidative stress, inflammation and IR and liver outcomes. The results from this pilot study support further investigation of NAC as a therapeutic agent in children with MASLD.

With the increase in obesity worldwide, its associated comorbidities, including nonalcoholic steatohepatitis (NASH), have become a public health problem that still lacks effective therapy. We have previously reported that mixed-lineage kinase 3–deficient (MLK3-deficient) mice are protected against diet-induced NASH. Given the critical need to identify new therapeutic agents, we sought to examine whether the small-molecule MLK3 inhibitor URMC099 would be effective in reversing diet-induced murine NASH. C57BL/6J mice were fed either a diet high in saturated fat, fructose, and cholesterol (FFC), or a chow diet for 24 weeks. Mice were treated with either URMC099 (10 mg/kg) twice daily by intraperitoneal injection or its vehicle during the last 2 weeks of the feeding study. FFC-fed mice receiving URMC099 had similar body weight, caloric intake, homeostatic model assessment of insulin resistance, metabolic phenotype, and hepatic steatosis compared with vehicle-treated mice. Furthermore, FFC-fed mice treated with URMC099 had less hepatic macrophage infiltration, activation, and proinflammatory polarization, as well as less liver injury and fibrosis when compared with vehicle-treated mice. In conclusion, URMC099 is well tolerated in mice without obvious toxicities and appears to be efficacious in reversing diet-induced NASH. Hence, URMC099 may serve as a therapeutic agent in human NASH.

AbstractBackground & AimsC‐Jun N‐terminal kinase (JNK) activation is pivotal in the development of nonalcoholic steatohepatitis (NASH). Mixed lineage kinase 3 (MLK) 3 is one of the mitogen activated protein kinase kinase kinase (MAP3K) that mediates JNK activation in the liver. Despite this concept, the role of MLK3 in modulating liver injury during nutrient excess has not been explored. Our aim was to determine if MLK3 deficient mice were protected against high fat high carbohydrate (HFHC) diet‐induced NASH.MethodsWe employed eight‐week‐old Mlk3−/− male C57BL/6J mice, and wild type (WT) mice C57BL/6J as controls. Mice were fed a HFHC or a chow diet adlib for 16 weeks.ResultsHepatic JNK activating phosphorylation was readily absent in the Mlk3−/− mice fed the HFHC diet, but not in WT mice. This inhibition of JNK activation was hepatoprotective. Despite a comparable increase in weight gain, hepatic steatosis by histological examination and hepatic triglyceride quantification was reduced in HFHC diet‐fed Mlk3−/− mice compared with WT mice. In addition, compared with the WT mice, HFHC diet‐fed Mlk3−/− mice had significantly attenuated liver injury as manifested by reduced ALT levels, hepatocyte apoptosis, markers of hepatic inflammation and indices of hepatic fibrogenesis.ConclusionOur results suggest that loss of MLK3 in mice is protective against HFHC diet‐induced NASH, in a weight‐independent fashion, through attenuation of JNK activation. MLK3 is a potential therapeutic target for the treatment of human NASH.

AbstractBariatric surgery elevates serum bile acids. Conjugated bile acid administration, such as tauroursodeoxycholic acid (TUDCA), improves insulin sensitivity, whereas short-circuiting bile acid circulation through ileal interposition surgery in rats raises TUDCA levels. We hypothesized that bariatric surgery outcomes could be recapitulated by short circuiting the normal enterohepatic bile circulation. We established a model wherein male obese rats underwent either bile diversion (BD) or Sham (SH) surgery. The BD group had a catheter inserted into the common bile duct and its distal end anchored into the middistal jejunum for 4–5 weeks. Glucose tolerance, insulin and glucagon-like peptide-1 (GLP-1) response, hepatic steatosis, and endoplasmic reticulum (ER) stress were measured. Rats post-BD lost significantly more weight than the SH rats. BD rats gained less fat mass after surgery. BD rats had improved glucose tolerance, increased higher postprandial glucagon-like peptide-1 response and serum bile acids but less liver steatosis. Serum bile acid levels including TUDCA concentrations were higher in BD compared to SH pair-fed rats. Fecal bile acid levels were not different. Liver ER stress (C/EBP homologous protein mRNA and pJNK protein) was decreased in BD rats. Bile acid gavage (TUDCA/ursodeoxycholic acid [UDCA]) in diet-induced obese rats, elevated serum TUDCA and concomitantly reduced hepatic steatosis and ER stress (C/EBP homologous protein mRNA). These data demonstrate the ability of alterations in bile acids to recapitulate important metabolic improvements seen after bariatric surgery. Further, our work establishes a model for focused study of bile acids in the context of bariatric surgery that may lead to the identification of therapeutics for metabolic disease.

ABSTRACTWith the epidemic of childhood obesity, nonalcoholic fatty liver disease (NAFLD) has become the most common cause of chronic liver disease in pediatrics. NAFLD is strongly associated with insulin resistance and increased level of serum free fatty acids (FFAs). FFAs have direct hepatotoxicity through the induction of an endoplasmic reticulum stress response and subsequently activation of the mitochondrial pathway of cell death. FFAs may also result in lysosomal dysfunction and alter death receptor gene expression. Lipoapoptosis is a key pathogenic process in NAFLD, and correlates with progressive inflammation, and fibrosis. Accumulation of triglyceride in the liver results from uptake and esterification of FFAs by the hepatocyte, and is less likely to be hepatotoxic per se. To date, there are no proven effective therapies that halt NAFLD progression or unfortunately improve prognosis in children. The cellular mechanisms of lipotoxicity are complex but provide potential therapeutic targets for NAFLD. In this review we discuss several potential therapeutic opportunities in detail including inhibition of apoptosis, c‐Jun‐N‐terminal kinase, and endoplasmic reticulum stress pathways.

ABSTRACTBackground:The relations between hepatic steatosis and histological features of hepatocyte injury in children with nonalcoholic fatty liver disease have yet to be examined. The aims of the present study were to establish associations between steatosis amount, type, and distribution in a well‐characterized group of children with biopsy‐proven nonalcoholic fatty liver disease (NAFLD).Patients and Methods:One hundred eight children with NAFLD seen in 5 centers were studied. Clinical and laboratory data were collected. Hematoxylin‐eosin and Masson trichrome stains were evaluated by 2 expert liver pathologists. Steatosis grade (0–3), type (macrovesicular, microvesicular, or mixed), and zone (1, 3, azonal, or panacinar) were determined. The NAFLD activity score and fibrosis stage were determined.Results:Median patient age was 12 years and median body mass index was 31 kg/m2. Fibrosis was present in 87%. The median NAFLD activity score was 4. Mild, moderate, and severe steatosis were present in 42%, 34%, and 24% of biopsies, respectively. Macrovesicular steatosis was present in 81% and mixed steatosis was present in 19%. Panacinar distribution of steatosis was most frequent (40%), followed by azonal (27%). Steatosis grade positively correlated with portal inflammation (P = 0.018). Azonal distribution positively correlated with presence of hepatocyte ballooning (P = 0.03). Biopsies with mixed steatosis were approximately 20 times more likely to have megamitochondria than those with macrovesicular steatosis alone (95% confidence interval 2.3–204.9). There was no relation between steatosis amount, type, or distribution to fibrosis stage.Conclusions:Specific histological patterns of steatosis in children are associated with histological markers of steatohepatitis. Ballooning and portal inflammation correlated well with features of steatosis.