How histopathologic changes in pediatric nonalcoholic fatty liver disease influence in vivo liver stiffness

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children and adolescents. About 30% of patients with NAFLD progress to the more severe condition of nonalcoholic steatohepatitis (NASH), which is typically diagnosed using liver biopsy. Liver stiffness (LS) quantified by elastography is a promising imaging marker for the noninvasive assessment of NAFLD and NASH in pediatric patients. However, the link between LS and specific histopathologic features used for clinical staging of NAFLD is not well defined. Furthermore, LS data reported in the literature can vary greatly due to the use of different measurement techniques. Uniquely, time-harmonic elastography (THE) based on ultrasound and magnetic resonance elastography (MRE) use the same mechanical stimulation, allowing us to compare LS in biopsy-proven NAFLD previously determined by THE and MRE in 67 and 50 adolescents, respectively. In the present work, we analyzed the influence of seven distinct histopathologic features on LS, including septal infiltration, bridging fibrosis, pericellular fibrosis, hepatocellular ballooning, portal inflammation, lobular inflammation, and steatosis. LS was highly correlated with periportal and lobular fibrosis as well as hepatocellular ballooning while no independent association was found for inflammation and steatosis. Based on this analysis, we propose a composite elastography score (CES) which includes the four key histopathologic features identified as mechanically relevant. Interestingly, CES-relevant histopathologic features were associated with zonal distribution patterns of pediatric NAFLD. Mechano-structural changes associated with NAFLD progression can be histopathologically staged using the CES, which is easily determined noninvasively based on LS measured by time-harmonic elastography.

Maternal Diet Alters Trained Immunity in the Pathogenesis of Pediatric NAFLD

Pediatric nonalcoholic fatty liver disease (NAFLD) affects 1 in 10 children in the US, increases risk of cirrhosis and transplantation in early adulthood, and shortens lifespan, even after transplantation. Exposure to maternal obesity and/or a diet high in fat, sugar and cholesterol is strongly associated with development of NAFLD in offspring. However, mechanisms by which "priming" of the immune system in early life increases susceptibility to NAFLD are poorly understood. Recent studies have focused on the role "non-reparative" macrophages play in accelerating inflammatory signals promoting fibrogenesis. In this Commentary, we review evidence that the pioneering gut bacteria colonizing the infant intestinal tract remodel the naïve immune system in the offspring. Epigenetic changes in hematopoietic stem and progenitor cells, induced by exposure to an obesogenic diet in utero, may skew lineage commitment of myeloid cells during gestation. Further, microbial dysbiosis in neonatal life contributes to training innate immune cell responsiveness in the gut, bone marrow, and liver, leading to developmental programming of pediatric NAFLD. Comprehensive understanding of how different gut bacteria and their byproducts shape development of the early innate immune system and microbiome will uncover early interventions to prevent NAFLD pathophysiology.

Advances in Pediatric Fatty Liver Disease: Pathogenesis, Diagnosis, and Treatment

Pediatric nonalcoholic fatty liver disease is an increasingly prevalent disease, but its pathophysiology is not fully elucidated, diagnosis is difficult and invasive, and therapeutic options are limited. This article addresses the recent advancements made in understanding the pathophysiology of nonalcoholic fatty liver disease, the development of less invasive diagnostic modalities, and emerging therapeutic options, including ongoing clinical trials in children.

Arterial function and structure after a 1-year lifestyle intervention in children with nonalcoholic fatty liver disease

BACKGROUND AND AIMS

Lifestyle modification has been the mainstay of controlling childhood obesity and has proved to be effective in reducing cardiovascular risk factors. However, it is currently unknown whether the subclinical atherosclerotic changes associated with nonalcoholic fatty liver disease (NAFLD) in such population are reversible.

METHODS AND RESULTS

We analyzed changes of brachial flow-mediated dilation (FMD), carotid intima-media thickness (cIMT), clinical, laboratory, and imaging data in 120 obese children with NAFLD, at the end of a 1-year intervention program with diet and physical exercise. The lifestyle intervention led to a significant mean decrease of body mass index (BMI)-standard deviation score (SDS), waist circumference (WC) and fat mass, along with diastolic blood pressure, triglycerides, liver enzymes, insulin, insulin resistance (homeostasis model assessment of insulin resistance, HOMA-IR), and high-sensitivity C-reactive protein. At the end of the study, FMD improved (P < 0.0001), while cIMT did not change significantly (P = 0.20). A significant decrease in hepatic fat content as measured by magnetic resonance imaging was also observed. Changes in FMD were inversely associated with changes in BMI-SDS, WC, total cholesterol, non-HDL cholesterol, liver enzymes, HOMA-IR, physical activity, and hepatic fat content. After including in the model all the significant variables as well as age, gender, pubertal status, and baseline FMD values, changes in FMD were significantly and independently associated with changes in WC and total cholesterol.

CONCLUSION

Also in obese children with NAFLD arterial function may be restored by improving metabolic risk factors and reducing visceral adiposity following a 1-year lifestyle intervention.

Arterial function and structure after a 1-year lifestyle intervention in children with nonalcoholic fatty liver disease

BACKGROUND AND AIMS

Lifestyle modification has been the mainstay of controlling childhood obesity and has proved to be effective in reducing cardiovascular risk factors. However, it is currently unknown whether the subclinical atherosclerotic changes associated with nonalcoholic fatty liver disease (NAFLD) in such population are reversible.

METHODS AND RESULTS

We analyzed changes of brachial flow-mediated dilation (FMD), carotid intima-media thickness (cIMT), clinical, laboratory, and imaging data in 120 obese children with NAFLD, at the end of a 1-year intervention program with diet and physical exercise. The lifestyle intervention led to a significant mean decrease of body mass index (BMI)-standard deviation score (SDS), waist circumference (WC) and fat mass, along with diastolic blood pressure, triglycerides, liver enzymes, insulin, insulin resistance (homeostasis model assessment of insulin resistance, HOMA-IR), and high-sensitivity C-reactive protein. At the end of the study, FMD improved (P < 0.0001), while cIMT did not change significantly (P = 0.20). A significant decrease in hepatic fat content as measured by magnetic resonance imaging was also observed. Changes in FMD were inversely associated with changes in BMI-SDS, WC, total cholesterol, non-HDL cholesterol, liver enzymes, HOMA-IR, physical activity, and hepatic fat content. After including in the model all the significant variables as well as age, gender, pubertal status, and baseline FMD values, changes in FMD were significantly and independently associated with changes in WC and total cholesterol.

CONCLUSION

Also in obese children with NAFLD arterial function may be restored by improving metabolic risk factors and reducing visceral adiposity following a 1-year lifestyle intervention.