Pediatric NASH therapies: A speedbump on the road to success

Effect of N-acetyl cysteine in children with metabolic dysfunction-associated steatotic liver disease-A pilot study

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 (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. 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 insulin resistance (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.

Fructose impairs fat oxidation: Implications for the mechanism of western diet-induced NAFLD

Increased fructose intake from sugar-sweetened beverages and highly processed sweets is a well-recognized risk factor for the development of obesity and its complications. Fructose strongly supports lipogenesis on a normal chow diet by providing both, a substrate for lipid synthesis and activation of lipogenic transcription factors. However, the negative health consequences of dietary sugar are best observed with the concomitant intake of a HFD. Indeed, the most commonly used obesogenic research diets, such as "Western diet", contain both fructose and a high amount of fat. In spite of its common use, how the combined intake of fructose and fat synergistically supports development of metabolic complications is not fully elucidated. Here we present the preponderance of evidence that fructose consumption decreases oxidation of dietary fat in human and animal studies. We provide a detailed review of the mitochondrial β-oxidation pathway. Fructose affects hepatic activation of fatty acyl-CoAs, decreases acylcarnitine production and impairs the carnitine shuttle. Mechanistically, fructose suppresses transcriptional activity of PPARα and its target CPT1α, the rate limiting enzyme of acylcarnitine production. These effects of fructose may be, in part, mediated by protein acetylation. Acetylation of PGC1α, a co-activator of PPARα and acetylation of CPT1α, in part, account for fructose-impaired acylcarnitine production. Interestingly, metabolic effects of fructose in the liver can be largely overcome by carnitine supplementation. In summary, fructose decreases oxidation of dietary fat in the liver, in part, by impairing acylcarnitine production, offering one explanation for the synergistic effects of these nutrients on the development of metabolic complications, such as NAFLD.

Dietary Counseling Aimed at Reducing Sugar Intake Yields the Greatest Improvement in Management of Weight and Metabolic Dysfunction in Children with Obesity

Pediatric obesity is a significant public health problem, the negative outcomes of which will challenge individual well-being and societal resources for decades to come. The objective of this study was to determine the effects of dietary counseling on weight management and metabolic abnormalities in children with obesity. One hundred and sixty-five patients aged 2−18 years old were studied over a two and a half year period. Data collected included demographic information, anthropometric assessment, laboratory measurements, and self-reported eating behaviors. Dietary counseling was provided at each visit. The data was analyzed from the first and last visits and the subjects were retrospectively divided into responders and non-responders based on a decrease in their BMI. After receiving dietary guidance, BMI decreased in 44% of the children, and these participants were classified as responders (BMI-R; n = 72). However, BMI did not improve in 56% of the participants, and these were classified as non-responders (BMI-NR; n = 93). At the initial visit, anthropometric measurements and dietary habits were similar between the groups. At the time of the last visit, mean change in BMI was −1.47 (SD 1.31) for BMI-R and +2.40 (SD 9.79) for BMI-NR. Analysis of food intake revealed that BMI-R significantly improved their dietary habits (p = 0.002) by reducing the intake of sugar-sweetened beverages (p = 0.019), processed foods (p = 0.002), sweets (p < 0.001), and unhealthy snacks (p = 0.009), as compared with BMI-NR. There was no change in the intake of second helpings, portion sizes, skipping meals, frequency of meals eaten at school, condiment use, intake of fruits and vegetables and consumption of whole grains between the groups. BMI-R also achieved an improvement in fasted glucose (p = 0.021), triglycerides (p < 0.001), and total cholesterol (p = 0.023), as compared to BMI-NR. In conclusion, children with obesity who were able to decrease their BMI implemented a significant reduction in consumption of foods with high sugar content. Focusing on reducing sugar intake may yield the biggest impact in terms of weight management and the improvement of metabolic abnormalities.