Reliability of histologic assessment for NAFLD and development of an expanded NAFLD activity score

Reliability of an Expanded Non-alcoholic Steatohepatitis Grading and Staging System for Assessment of Disease Activity and Fibrosis

The nonalcoholic steatohepatitis clinical research network (NASH-CRN) system is commonly used for histologic assessment of disease activity and fibrosis in NASH. Despite this, the system does not fully capture the range of disease activity and fibrosis. As such, an expanded NAS (E-NAS) grading and staging system with a calculated E-NAS index was developed by our group. In this follow up study, we aim to revalidate the E-NAS system and compare its reliability to existing systems. Hematoxylin and eosin and trichrome stained sections from 40 liver biopsies were reviewed digitally by four hepatopathologists and assessed using the NASH-CRN and E-NAS systems as well as a modified Ishak fibrosis stage. The pathologist's gestalt impression of disease activity and fibrosis was scored on a Visual Analogue Scale (VAS), which ranged from 0 (no activity/fibrosis) to 100 (the worst activity/fibrosis ever seen). Inter-rater reliability was assessed, and Spearman correlation coefficients were calculated. The E-NAS index had higher inter-rater agreement versus the NAS score (ICC 0.70 vs 0.61). The inter-rater agreement for ballooning in the E-NAS system was also higher at 0.67 compared to the NAS (ICC 0.60). ICCs for fibrosis were comparable between all the systems assessed (0.78 to 0.88). Finally, the calculated E-NAS index was higher with increasing stage of fibrosis compared to the NAS suggesting that it associates better with fibrosis. In summary, the E-NAS system demonstrates substantial inter-rater reliability as well as improved correlation with disease activity VAS and fibrosis compared to the NAS score.

Extract of Silphium perfoliatum L. improve lipid accumulation in NAFLD mice by regulating AMPK/FXR signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Globally, the incidence rate and number of patients with nonalcoholic fatty liver disease are increasing, which has become one of the greatest threats to human health. However, there is still no effective therapy and medicine so far. Silphium perfoliatum L. is a perennial herb native to North America, which is used to improve physical fitness and treat liver and spleen related diseases in the traditional medicinal herbs of Indian tribes. This herb is rich in chlorogenic acids, which have the functions of reducing blood lipids, losing weight and protecting liver. However, the effect of these compounds on nonalcoholic fatty liver disease remains unclear.

AIM OF THE STUDY

Clarify the therapeutic effects and mechanism of the extract (CY-10) rich in chlorogenic acid and its analogues from Silphium perfoliatum L. on non-alcoholic fatty liver disease, and to determine the active compounds.

MATERIALS AND METHODS

A free fatty acid-induced steatosis model of HepG2 cells was established to evaluate the in vitro activity of CY-10 in promoting lipid metabolism. Further, a high-fat diet-induced NAFLD model in C57BL/6 mice was established to detect the effects of CY-10 on various physiological and biochemical indexes in mice, and to elucidate the in vivo effects of the extract on regulating lipid metabolism, anti-inflammation and hepatoprotection, and nontarget lipid metabolomics was performed to analyze differential metabolites of fatty acids in the liver. Subsequently, western blotting and immunohistochemistry were used to analyze the target of the extract and elucidate its mechanism of action. Finally, the active compounds in CY-10 were elucidated through in vitro activity screening.

RESULTS

The results indicated that CY-10 significantly attenuated lipid droplet deposition in HepG2 cells. The results of in vivo experiments showed that CY-10 significantly reduce HFD-induced mouse body weight and organ index, improve biochemical indexes, oxidation levels and inflammatory responses in the liver and serum, thereby protecting the liver tissue. It can promote the metabolism of unsaturated fatty acids in the liver and reduce the generation of saturated fatty acids. Furthermore, it is clarified that CY-10 can promote lipid metabolism balance by regulating AMPK/FXR/SREPB-1c/PPAR-γ signal pathway. Ultimately, the main active compound was proved to be cryptochlorogenic acid, which has a strong promoting effect on the metabolism of fatty acids in cells. Impressively, the activities of CY-10 and cryptochlorogenic acid were stronger than simvastatin in vitro and in vivo.

CONCLUSION

For the first time, it is clarified that the extract rich in chlorogenic acids and its analogues in Silphium perfoliatum L. have good therapeutic effects on non-alcoholic fatty liver disease. It is confirmed that cryptochlorogenic acid is the main active compound and has good potential for medicine.

Hepatic Fibrosis and Cancer: The Silent Threats of Metabolic Syndrome

Metabolic dysfunction-associated steatotic (fatty) liver disease (MASLD), previously termed non-alcoholic fatty liver disease, is a worldwide epidemic that can lead to hepatic inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). The disease is typically a component of the metabolic syndrome that accompanies obesity, and is often overlooked because the liver manifestations are clinically silent until late-stage disease is present (i.e., cirrhosis). Moreover, Asian populations, including Koreans, have a higher fraction of patients who are lean, yet their illness has the same prognosis or worse than those who are obese. Nonetheless, ongoing injury can lead to hepatic inflammation and ballooning of hepatocytes as classic features. Over time, fibrosis develops following activation of hepatic stellate cells, the liver's main fibrogenic cell type. The disease is usually more advanced in patients with type 2 diabetes mellitus, indicating that all diabetic patients should be screened for liver disease. Although there has been substantial progress in clarifying pathways of injury and fibrosis, there no approved therapies yet, but current research seeks to uncover the pathways driving hepatic inflammation and fibrosis, in hopes of identifying new therapeutic targets. Emerging molecular methods, especially single cell sequencing technologies, are revolutionizing our ability to clarify mechanisms underlying MASLD-associated fibrosis and HCC.

Diosgenin as a substitute for cholesterol alleviates NAFLD by affecting CYP7A1 and NPC1L1-related pathway

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) rapidly becomes the leading cause of end-stage liver disease or liver transplantation. Nowadays, there has no approved drug for NAFLD treatment. Diosgenin as the structural analogue of cholesterol attenuates hypercholesterolemia by inhibiting cholesterol metabolism, which is an important pathogenesis in NAFLD progression. However, there has been no few report concerning its effects on NAFLD so far.

METHODS

Using a high-fat diet & 10% fructose-feeding mice, we evaluated the anti-NAFLD effects of diosgenin. Transcriptome sequencing, LC/MS analysis, molecular docking simulation, molecular dynamics simulations and Luci fluorescent reporter gene analysis were used to evaluate pathways related to cholesterol metabolism.

RESULTS

Diosgenin treatment ameliorated hepatic dysfunction and inhibited NAFLD formation including lipid accumulation, inflammation aggregation and fibrosis formation through regulating cholesterol metabolism. For the first time, diosgenin was structurally similar to cholesterol, down-regulated expression of CYP7A1 and regulated cholesterol metabolism in the liver (p < 0.01) and further affecting bile acids like CDCA, CA and TCA in the liver and feces. Besides, diosgenin decreased expression of NPC1L1 and suppressed cholesterol transport (p < 0.05). Molecular docking and molecular dynamics further proved that diosgenin was more strongly bound to CYP7A1. Luci fluorescent reporter gene analysis revealed that diosgenin concentration-dependently inhibited the enzymes activity of CYP7A1.

CONCLUSION

Our findings demonstrated that diosgenin was identified as a specific regulator of cholesterol metabolism, which pave way for the design of novel clinical therapeutic strategies.

Artificial intelligence-assisted digital pathology for non-alcoholic steatohepatitis: current status and future directions

The worldwide prevalence of non-alcoholic steatohepatitis (NASH) is increasing, causing a significant medical burden, but no approved therapeutics are currently available. NASH drug development requires histological analysis of liver biopsies by expert pathologists for trial enrolment and efficacy assessment, which can be hindered by multiple issues including sample heterogeneity, inter-reader and intra-reader variability, and ordinal scoring systems. Consequently, there is a high unmet need for accurate, reproducible, quantitative, and automated methods to assist pathologists with histological analysis to improve the precision around treatment and efficacy assessment. Digital pathology (DP) workflows in combination with artificial intelligence (AI) have been established in other areas of medicine and are being actively investigated in NASH to assist pathologists in the evaluation and scoring of NASH histology. DP/AI models can be used to automatically detect, localise, quantify, and score histological parameters and have the potential to reduce the impact of scoring variability in NASH clinical trials. This narrative review provides an overview of DP/AI tools in development for NASH, highlights key regulatory considerations, and discusses how these advances may impact the future of NASH clinical management and drug development. This should be a high priority in the NASH field, particularly to improve the development of safe and effective therapeutics.

Discovery of LH10, a novel fexaramine-based FXR agonist for the treatment of liver disease

Farnesoid X receptor (FXR) was considered as a promising drug target in the treatment of cholestasis, drug-induced liver injury, and non-alcoholic steatohepatitis (NASH). However, the existing FXR agonists have shown different degrees of side effects in clinical trials without clear interpretation. MET-409 in clinical phase Ⅲ, has been proven significantly fewer side effects than that of other FXR agonists. This may be due to the completely different structure of FEX and other non-steroidal FXR agonists. Herein, the structure-based drug design was carried out based on FEX, and the more active FXR agonist LH10 (FEX EC50 = 0,3 μM; LH10 EC50 = 0.14 μM)) was screened out by the comprehensive SAR studies. Furthermore, LH10 exhibited robust hepatoprotective activity on the ANIT-induced cholestatic model and APAP-induced acute liver injury model, which was even better than positive control OCA. In the nonalcoholic steatohepatitis (NASH) model, LH10 significantly improved the pathological characteristics of NASH by regulating several major pathways including lipid metabolism, inflammation, oxidative stress, and fibrosis. With the above attractive results, LH10 is worthy of further evaluation as a novel agent for the treatment of liver disorders.

Digital pathology for nonalcoholic steatohepatitis assessment

Histological assessment of nonalcoholic fatty liver disease (NAFLD) has anchored knowledge development about the phenotypes of the condition, their natural history and their clinical course. This fact has led to the use of histological assessment as a reference standard for the evaluation of efficacy of drug interventions for nonalcoholic steatohepatitis (NASH) - the more histologically active form of NAFLD. However, certain limitations of conventional histological assessment systems pose challenges in drug development. These limitations have spurred intense scientific and commercial development of machine learning and digital approaches towards the assessment of liver histology in patients with NAFLD. This research field remains an area in rapid evolution. In this Perspective article, we summarize the current conventional assessment of NASH and its limitations, the use of specific digital approaches for histological assessment, and their application to the study of NASH and its response to therapy. Although this is not a comprehensive review, the leading tools currently used to assess therapeutic efficacy in drug development are specifically discussed. The potential translation of these approaches to support routine clinical assessment of NAFLD and an agenda for future research are also discussed.

Utility of pathologist panels for achieving consensus in NASH histologic scoring in clinical trials: Data from a phase 3 study

BACKGROUND

Liver histopathologic assessment is the accepted surrogate endpoint in NASH trials; however, the scoring of NASH Clinical Research Network (CRN) histologic parameters is limited by intraobserver and interobserver variability. We designed a consensus panel approach to minimize variability when using this scoring system. We assessed agreement between readers, estimated linear weighted kappas between 2 panels, compared them with published pairwise kappa estimates, and addressed how agreement or disagreement might impact the precision and validity of the surrogate efficacy endpoint in NASH trials.

METHODS

Two panels, each comprising 3 liver fellowship-trained pathologists who underwent NASH histology training, independently evaluated scanned whole slide images, scoring fibrosis, inflammation, hepatocyte ballooning, and steatosis from baseline and month 18 biopsies for 100 patients from the precirrhotic NASH study REGENERATE. The consensus score for each parameter was defined as agreement by ≥2 pathologists. If consensus was not reached, all 3 pathologists read the slide jointly to achieve a consensus score.

RESULTS

Between the 2 panels, the consensus was 97%-99% for steatosis, 91%-93% for fibrosis, 88%-92% for hepatocyte ballooning, and 84%-91% for inflammation. Linear weighted kappa scores between panels were similar to published NASH CRN values.

CONCLUSIONS

A panel of 3 trained pathologists independently scoring 4 NASH CRN histology parameters produced high consensus rates. Interpanel kappa values were comparable to NASH CRN metrics, supporting the accuracy and reproducibility of this method. The high concordance for fibrosis scoring was reassuring, as fibrosis is predictive of liver-specific outcomes and all-cause mortality.

Isotope Labeling and Biochemical Assessment of Liver-Triacylglycerol in Patients with Different Levels of Histologically-Graded Liver Disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) prevalence is rapidly growing, and fatty liver has been found in a quarter of the US population. Increased liver lipids, particularly those derived from the pathway of de novo lipogenesis (DNL), have been identified as a hallmark feature in individuals with high liver fat. This has led to much activity in basic science and drug development in this area. No studies to date have investigated the contribution of DNL across a spectrum of disease, although it is clear that inhibition of DNL has been shown to reduce liver fat.

OBJECTIVES

The purpose of this study was to determine whether liver lipid synthesis increases across the continuum of liver injury.

METHODS

Individuals (n = 49) consumed deuterated water for 10 d before their scheduled bariatric surgeries to label DNL; blood and liver tissue samples were obtained on the day of the surgery. Liver lipid concentrations were quantitated, and levels of protein and gene expression assessed.

RESULTS

Increased liver DNL, measured isotopically, was significantly associated with liver fatty acid synthase protein content (R = 0.470, P = 0.003), total steatosis assessed by histology (R = 0.526, P = 0.0008), and the fraction of DNL fatty acids in plasma very low-density lipoprotein-triacylglycerol (R = 0.747, P < 0.001). Regression analysis revealed a parabolic relationship between fractional liver DNL (percent) and NAFLD activity score (R = 0.538, P = 0.0004).

CONCLUSION

These data demonstrate that higher DNL is associated with early to mid stages of liver disease, and this pathway may be an effective target for the treatment of NAFLD and nonalcoholic steatohepatitis. This study was registered at clinicaltrials.gov as NCT03683589.

Noninvasive Tests Used in Risk Stratification of Patients with Nonalcoholic Fatty Liver Disease

As the prevalence of obesity and type 2 diabetes increases around the world, the prevalence of nonalcoholic fatty liver disease (NAFLD) has grown proportionately. Although most patients with NAFLD do not experience progressive liver disease, about 15% to 20% of those with nonalcoholic steatohepatitis can and do progress. Because liver biopsy's role in NAFLD has become increasingly limited, efforts have been undertaken to develop non-invasive tests (NITs) to help identify patients at high risk of progression. The following article discusses the NITs that are available to determine the presence of NAFLD as well as high-risk NAFLD.

AI-based histologic scoring enables automated and reproducible assessment of enrollment criteria and endpoints in NASH clinical trials

Clinical trials in nonalcoholic steatohepatitis (NASH) require histologic scoring for assessment of inclusion criteria and endpoints. However, guidelines for scoring key features have led to variability in interpretation, impacting clinical trial outcomes. We developed an artificial intelligence (AI)-based measurement (AIM) tool for scoring NASH histology (AIM-NASH). AIM-NASH predictions for NASH Clinical Research Network (CRN) grades of necroinflammation and stages of fibrosis aligned with expert consensus scores and were reproducible. Continuous scores produced by AIM-NASH for key histological features of NASH correlated with mean pathologist scores and with noninvasive biomarkers and strongly predicted patient outcomes. In a retrospective analysis of the ATLAS trial, previously unmet pathological endpoints were met when scored by the AIM-NASH algorithm alone. Overall, these results suggest that AIM-NASH may assist pathologists in histologic review of NASH clinical trials, reducing inter-rater variability on trial outcomes and offering a more sensitive and reproducible measure of patient therapeutic response.

Non-alcoholic fatty liver disease: the pathologist's perspective

Non-alcoholic fatty liver disease (NAFLD) is a spectrum of diseases characterized by fatty accumulation in hepatocytes, ranging from steatosis, non-alcoholic steatohepatitis, to cirrhosis. While histopathological evaluation of liver biopsies plays a central role in the diagnosis of NAFLD, limitations such as the problem of interobserver variability still exist and active research is underway to improve the diagnostic utility of liver biopsies. In this article, we provide a comprehensive overview of the histopathological features of NAFLD, the current grading and staging systems, and discuss the present and future roles of liver biopsies in the diagnosis and prognostication of NAFLD.

The nonalcoholic steatohepatitis extended hepatocyte ballooning score: histologic classification and clinical significance

BACKGROUND AND AIMS

The NAFLD activity score was developed to measure histologic changes in NAFLD during therapeutic trials. Hepatocyte ballooning (HB) is the most specific feature in steatohepatitis diagnosis, yet the impact of variations in HB has not been incorporated.

APPROACH AND RESULTS

Liver biopsies from patients enrolled in the NASH Clinical Research Network with an initial diagnosis of NASH or NAFL (n=1688) were evaluated to distinguish classic hepatocyte ballooning (cHB) from smaller, nonclassic hepatocyte ballooning (nHB), and also to designate severe ballooning and assign an extended hepatocyte ballooning (eB) score [0 points, no ballooning (NB); 1 point, few or many nHB; 2 points, few cHB; 3 points, many cHB; 4 points, severe cHB] to the biopsy assessment. The eB score was reproducible among NASH CRN liver pathologists (weighted kappa 0.76) and was significantly associated with older age (mean 52.1 y, cHB; 48.5 y, nHB, p<0.001), gender (72.3% female, cHB; 54.5% female, nHB, p<0.001), diabetes (49.8% diabetes, cHB; 28.2% diabetes, nHB, p<0.001), metabolic syndrome (68.5% metabolic syndrome, nHB; 50.2% metabolic syndrome, NB, p<0.001), and body mass index [33.2, 34.2, 35 mean body mass index (kg/m2); NB, nHB, and cHB, respectively, p<0.05]. Finally, fibrosis stage, as a marker of disease severity, was significantly correlated with the eB score (p<0.001).

CONCLUSIONS

The eB score allows for a reproducible and more precise delineation of the range of ballooned hepatocyte morphology and corresponds with both clinical features of NASH and fibrosis stage.

Non-invasive biomarkers for liver inflammation in non-alcoholic fatty liver disease: present and future

Inflammation is the key driver of liver fibrosis progression in non-alcoholic fatty liver disease (NAFLD). Unfortunately, it is often challenging to assess inflammation in NAFLD due to its dynamic nature and poor correlation with liver biochemical markers. Liver histology keeps its role as the standard tool, yet it is well-known for substantial sampling, intraobserver, and interobserver variability. Serum proinflammatory cytokines and apoptotic markers, namely cytokeratin-18, are well-studied with reasonable accuracy, whereas serum metabolomics and lipidomics have been adopted in some commercially available diagnostic models. Ultrasound and computed tomography imaging techniques are attractive due to their wide availability; yet their accuracies may not be comparable with magnetic resonance imaging-based tools. Machine learning and deep learning models, be they supervised or unsupervised learning, are promising tools to identify various subtypes of NAFLD, including those with dominating liver inflammation, contributing to sustainable care pathways for NAFLD.

Labeled breath tests in patients with NASH: Octanoate oxidation relates best to measures of glucose metabolism

In vivo methods to estimate human liver mitochondrial activity are lacking and this project's goal was to use a non-invasive breath test to quantify complete mitochondrial fat oxidation and determine how test results changed when liver disease state was altered over time. Patients with suspected non-alcoholic fatty liver disease (NAFLD; 9 men, 16 women, 47 ± 10 years, 113 ± 23 kg) underwent a diagnostic liver biopsy and liver tissue was histologically scored by a pathologist using the NAFLD activity score (0-8). To assess liver oxidation activity, a labeled medium chain fatty acid was consumed orally (23.4 mg ¹³C₄-octanoate) and breath samples collected over 135 min. Total CO₂ production rates were measured using breath ¹³CO₂ analysis by isotope ratio mass spectrometry. Fasting endogenous glucose production (EGP) was measured using an IV infusion of ¹³C₆-glucose. At baseline, subjects oxidized 23.4 ± 3.9% (14.9%-31.5%) of the octanoate dose and octanoate oxidation (OctOx) was negatively correlated with fasting plasma glucose (r = -0.474, p = 0.017) and EGP (r = -0.441, p = 0.028). Twenty-two subjects returned for repeat tests 10.2 ± 1.0 months later, following lifestyle treatment or standardized care. OctOx (% dose/kg) was significantly greater across all subjects (p = 0.044), negatively related to reductions in EGP (r = -0.401, p = 0.064), and tended to correlate with reduced fasting glucose (r = -0.371, p = 0.090). Subjects exhibited reductions in steatosis (p = 0.007) which tended to correlate with increased OctOx (% of dose/kg, r = -0.411, p = 0.058). Based on our findings, the use of an ¹³C-octanoate breath test may be an indicator of hepatic steatosis and glucose metabolism, but these relationships require verification through larger studies in NAFLD populations.