Development and validation of pFIB scores for exclusion of significant liver fibrosis in pediatric MASLD.

BACKGROUND AIMS: Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most prevalent pediatric liver disease, yet accurate risk scores for referral of children/adolescents with suspected clinically significant liver fibrosis are currently lacking. APPROACH RESULTS: Clinical and biochemical variables were collected in a prospective cohort of 327 children and adolescents with severe obesity, in whom liver fibrosis was evaluated by transient elastography. Logistic regression was performed to establish continuous (pFIB-c) and simplified (pFIB-6) diagnostic scores that accurately exclude significant (≥F2) fibrosis. Performance for each was compared to established non-invasive fibrosis scores. These scores were validated in elastography (n=504) and multiple biopsy-proven MASLD (n=261) cohorts. Patient sex, ethnicity, weight z-score, HOMA-IR index, ALT, and presence of hypertension were included in the scores. The pFIB-c and pFIB-6 exhibited good discriminatory capacity (c-statistic of 0.839 and 0.826), outperforming existing indices. Negative predictive values (NPV) were >90% for both scores in the derivation and elastography validation cohorts. Performance in the histological cohorts varied (AUROCs for the pFIB-c between 0.710 and 0.770), as the scores were less accurate when applied to populations in tertiary referral centers characterized by a high prevalence of significant fibrosis and high ALT levels. CONCLUSIONS: Analyzing several cohorts totaling approximately 1100 children and adolescents, we developed novel risk scores incorporating readily available clinical variables. In accordance with the aim of excluding pediatric MASLD-associated fibrosis, the scores performed better in non-selected cohorts of children and adolescents living with obesity than in patients referred to tertiary liver units.

Noninvasive scores are poorly predictive of histological fibrosis in paediatric fatty liver disease.

OBJECTIVES: Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children. Roughly a quarter of paediatric patients with NAFLD develop nonalcoholic steatohepatitis and fibrosis. Here, we evaluated the diagnostic accuracy of previously published noninvasive fibrosis scores to predict liver fibrosis in a large European cohort of paediatric patients with NAFLD. METHODS: The 457 patients with biopsy-proven NAFLD from 10 specialized centers were included. We assessed diagnostic accuracy for the prediction of any (F ≥ 1), moderate (F ≥ 2) or advanced (F ≥ 3) fibrosis for the AST/platelet ratio (APRI), Fibrosis 4 score (FIB-4), paediatric NAFLD fibrosis score (PNFS) and paediatric NAFLD fibrosis index (PNFI). RESULTS: Patients covered the full spectrum of fibrosis (F0: n = 103; F1: n = 230; F2: n = 78; F3: n = 44; F4: n = 2). None of the scores were able to accurately distinguish the presence of any fibrosis from no fibrosis. For the detection of moderate fibrosis, area under the receiver operating characteristic curve (AUROC) were: APRI: 0.697, FIB-4: 0.663, PNFI: 0.515, PNFS: 0.665, while for detection of advanced fibrosis AUROCs were: APRI: 0.759, FIB-4: 0.611, PNFI: 0.521, PNFS: 0.712. Fibrosis scores showed no diagnostic benefit over using ALT ≤ 50/ > 50 IU/L as a cut-off. CONCLUSIONS: Established fibrosis scores lack diagnostic accuracy to replace liver biopsy for staging of fibrosis, giving similar results as compared to using ALT alone. New diagnostic tools are needed for Noninvasive risk-stratification in paediatric NAFLD.

Interactions between nocturnal melatonin secretion, metabolism, and sleeping behavior in adolescents with obesity.

BACKGROUND/OBJECTIVES: Sleeping behavior and individual prospensity in sleep timing during a 24 h period, known as chronotypes, are underestimated factors, which may favor the development of obesity and metabolic diseases. Furthermore, melatonin is known to play an important role in circadian rhythm, but was also suggested to directly influence metabolism and bodyweight regulation. Since disturbed and shifted sleep rhythms have been observed in adolescents with obesity, this study aimed to investigate potential interactions between melatonin secretion, chronobiology, and metabolism. In addition, the influence of artificial light especially emitted by electronic devices on these parameters was of further interest. SUBJECTS/METHODS: We performed a cross-sectional study including 149 adolescents (mean age 14.7 ± 2.1 years) with obesity. Metabolic blood parameters (e.g., cholesterol, triglycerides, uric acid, and insulin) were obtained from patients and correlated with nocturnal melatonin secretion. Melatonin secretion was determined by measuring 6-sulfatoxymelatonin (MT6s), the major metabolite of melatonin in the first-morning urine, and normalized to urinary creatinine levels to account for the urinary concentration. Chronobiologic parameters were further assessed using the Munich ChronoType Questionnaire. RESULTS: Subjects with insulin resistance (n = 101) showed significantly lower nocturnal melatonin levels compared to those with unimpaired insulin secretion (p = 0.006). Furthermore, triglyceride (p = 0.012) and elevated uric acid levels (p = 0.029) showed significant associations with melatonin secretion. Patients with late chronotype showed a higher incidence of insulin resistance (p = 0.018). Moreover, late chronotype and social jetlag were associated with the time and duration of media consumption. CONCLUSION: We identified an association of impaired energy metabolism and lower nocturnal melatonin secretion in addition to late chronotype and increased social jetlag (misalignment of biological and social clocks) in adolescents with obesity. This might point towards a crucial role of chronotype and melatonin secretion as risk factors for the development of pediatric and adolescent obesity.

Gustatory Function Can Improve after Multimodal Lifestyle Intervention: A Longitudinal Observational Study in Pediatric Patients with Obesity.

Introduction: Obesity is a major health burden in children and adolescents. One influential factor is the choice of food, which is partly determined by gustatory perception. Cross-sectional studies have provided evidence that gustatory function is reduced in patients with obesity compared to individuals with normal weight. This longitudinal study was aimed at investigating potential effects of a multimodal lifestyle intervention program on gustatory function in pediatric patients with obesity. Methods: Gustatory perception of five different taste qualities (sweet, sour, salty, bitter, and umami) was assessed in n = 102 patients (age 6-18) with obesity (BMI >97th percentile). Testing was performed before (T0) and after (T1) a residential multimodal weight reduction program between June and December 2015 using well-established taste strips. Results: Overall, identification performance increased between T0 and T1. Patients were most successful at identifying the taste quality sweet at both time points and reached higher scores at identifying umami and bitter at T1 compared to T0. Moreover, patients rated the highest concentration of sweet significantly sweeter at T1 compared to T0. Conclusion: Gustatory function can improve after a multimodal lifestyle intervention program in pediatric patients with obesity. This may lead to a modified choice of food, possibly resulting in a long-term therapeutic success. Therefore, these findings underline the importance of professional nutritional counseling as part of treatment for obesity.

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.

Regulation of the cytochrome P450 epoxyeicosanoid pathway is associated with distinct histologic features in pediatric non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is a significant health burden in obese children for which there is currently no specific therapy. Preclinical studies indicate that epoxyeicosanoids, a class of bioactive lipid mediators that are generated by cytochrome P450 (CYP) epoxygenases and inactivated by the soluble epoxide hydrolase (sEH), play a protective role in NAFLD. We performed a comprehensive lipidomics analysis using liver tissue and blood samples of 40 children with NAFLD. Proteomics was performed to determine CYP epoxygenase and sEH expressions. Hepatic epoxyeicosanoids significantly increased with higher grades of steatosis, while their precursor PUFAs were unaltered. Concomitantly, total CYP epoxygenase activity increased while protein level and activity of sEH decreased. In contrast, hepatic epoxyeicosanoids showed a strong decreasing trend with higher stages of fibrosis, accompanied by a decrease of CYP epoxygenase activity and protein expression. These findings suggest that the CYP epoxygenase/sEH pathway represents a potential pharmacologic target for the treatment of NAFLD.

Hepatocyte-specific NRF2 activation controls fibrogenesis and carcinogenesis in steatohepatitis.

BACKGROUND & AIMS: In chronic liver diseases, inflammation induces oxidative stress and thus may contribute to the progression of liver injury, fibrosis, and carcinogenesis. The KEAP1/NRF2 axis is a major regulator of cellular redox balance. In the present study, we investigated whether the KEAP1/NRF2 system is involved in liver disease progression in humans and mice. METHODS: The clinical relevance of oxidative stress was investigated by liver RNA sequencing in a well-characterized cohort of patients with non-alcoholic fatty liver disease (n = 63) and correlated with histological and clinical parameters. For functional analysis, hepatocyte-specific Nemo knockout (NEMOΔhepa) mice were crossed with hepatocyte-specific Keap1 knockout (KEAP1Δhepa) mice. RESULTS: Immunohistochemical analysis of human liver sections showed increased oxidative stress and high NRF2 expression in patients with chronic liver disease. RNA sequencing of liver samples in a human pediatric NAFLD cohort revealed a significant increase of NRF2 activation correlating with the grade of inflammation, but not with the grade of steatosis, which could be confirmed in a second adult NASH cohort. In mice, microarray analysis revealed that Keap1 deletion induces NRF2 target genes involved in glutathione metabolism and xenobiotic stress (e.g., Nqo1). Furthermore, deficiency of one of the most important antioxidants, glutathione (GSH), in NEMOΔhepa livers was rescued after deleting Keap1. As a consequence, NEMOΔhepa/KEAP1Δhepa livers showed reduced apoptosis compared to NEMOΔhepa livers as well as a dramatic downregulation of genes involved in cell cycle regulation and DNA replication. Consequently, NEMOΔhepa/KEAP1Δhepa compared to NEMOΔhepa livers displayed decreased fibrogenesis, lower tumor incidence, reduced tumor number, and decreased tumor size. CONCLUSIONS: NRF2 activation in patients with non-alcoholic steatohepatitis correlates with the grade of inflammation, but not steatosis. Functional analysis in mice demonstrated that NRF2 activation in chronic liver disease is protective by ameliorating fibrogenesis, initiation and progression of hepatocellular carcinogenesis. LAY SUMMARY: The KEAP1 (Kelch-like ECH-associated protein-1)/NRF2 (erythroid 2-related factor 2) axis has a major role in regulating cellular redox balance. Herein, we show that NRF2 activity correlates with the grade of inflammation in patients with non-alcoholic steatohepatitis. Functional studies in mice actually show that NRF2 activation, resulting from KEAP1 deletion, protects against fibrosis and cancer.

The Pathogenic TSH ß-subunit Variant C105Vfs114X Causes a Modified Signaling Profile at TSHR.

1) Background: Central congenital hypothyroidism (CCH) is a rare endocrine disorder that can be caused by mutations in the ß-subunit of thyrotropin (TSHB). The TSHB mutation C105Vfs114X leads to isolated thyroid-stimulating-hormone-(TSH)-deficiency and results in a severe phenotype. The aim of this study was to gain more insight into the underlying molecular mechanism and the functional effects of this mutation based on two assumptions: a) the three-dimensional (3D) structure of TSH should be modified with the C105V substitution, and/or b) whether the C-terminal modifications lead to signaling differences. 2) Methods: wild-type (WT) and different mutants of hTSH were generated in human embryonic kidney 293 cells (HEK293 cells) and TSH preparations were used to stimulate thyrotropin receptor (TSHR) stably transfected into follicular thyroid cancer cells (FTC133-TSHR cells) and transiently transfected into HEK293 cells. Functional characterization was performed by determination of Gs, mitogen activated protein kinase (MAPK) and Gq/11 activation. 3) Results: The patient mutation C105Vfs114X and further designed TSH mutants diminished cyclic adenosine monophosphate (cAMP) signaling activity. Surprisingly, MAPK signaling for all mutants was comparable to WT, while none of the mutants induced PLC activation. 4) Conclusion: We characterized the patient mutation C105Vfs114X concerning different signaling pathways. We identified a strong decrease of cAMP signaling induction and speculate that this could, in combination with diverse signaling regarding the other pathways, accounting for the patient's severe phenotype.

Minireview: Insights Into the Structural and Molecular Consequences of the TSH-ß Mutation C105Vfs114X.

Naturally occurring thyrotropin (TSH) mutations are rare, which is also the case for the homologous heterodimeric glycoprotein hormones (GPHs) follitropin (FSH), lutropin (LH), and choriogonadotropin (CG). Patients with TSH-inactivating mutations present with central congenital hypothyroidism. Here, we summarize insights into the most frequent loss-of-function ß-subunit of TSH mutation C105Vfs114X, which is associated with isolated TSH deficiency. This review will address the following question. What is currently known on the molecular background of this TSH variant on a protein level? It has not yet been clarified how C105Vfs114X causes early symptoms in affected patients, which are comparably severe to those observed in newborns lacking any functional thyroid tissue (athyreosis). To better understand the mechanisms of this mutant, we have summarized published reports and complemented this information with a structural perspective on GPHs. By including the ancestral TSH receptor agonist thyrostimulin and pathogenic mutations reported for FSH, LH, and choriogonadotropin in the analysis, insightful structure function and evolutionary restrictions become apparent. However, comparisons of immunogenicity and bioactivity of different GPH variants is hindered by a lack of consensus for functional analysis and the diversity of used GPH assays. Accordingly, relevant gaps of knowledge concerning details of GPH mutation-related effects are identified and highlighted in this review. These issues are of general importance as several previous and recent studies point towards the high impact of GPH variants in differential signaling regulation at GPH receptors (GPHRs), both endogenously and under diseased conditions. Further improvement in this area is of decisive importance for the development of novel targeted therapies.