NASH in Lean Individuals Younes, Ramy; Bugianesi, Elisabetta
Seminars in liver disease,
02/2019, Letnik:
39, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Nonalcoholic fatty liver disease (NAFLD) is generally associated with obesity and the related comorbidities but it can also develop in subjects with a body mass index (BMI) within the ethnic-specific ...cutoff of 25 kg/m
BMI in Caucasian and 23 kg/m
in Asian subjects, the so-called "lean" NAFLD. This sub-phenotype of NAFLD patients has been described across populations of different ethnicity, particularly in Asia, but it can be diagnosed in 10 to 20% of nonobese Americans and Caucasians. Pathophysiological mechanisms underpinning the "lean" phenotype are not completely understood, but they may include a more dysfunctional fat (visceral obesity, differences in adipocyte differentiation and altered lipid turnover), altered body composition (decreased muscle mass), a genetic background, not limited to patatin-like phospholipase domain-containing protein 3 (PNPLA3) C > G polymorphisms, epigenetic changes occurring early in life and a different pattern of gut microbiota. Lean subjects with NAFLD have milder features of the metabolic syndrome when compared with obese patients. Nonetheless they have a higher prevalence of metabolic alterations (e.g., dyslipidemia, arterial hypertension, insulin resistance, and diabetes) compared with healthy controls. Data on histological severity are controversial, but they can develop the full spectrum of liver disease associated with nonalcoholic steatohepatitis NASH. Since lean NAFLD usually present with less obesity-related comorbidities, it is commonly believed that this group would follow a relatively benign clinical course but recent data challenge this concept. Here, the authors describe the current knowledge about NAFLD in lean individuals and highlight the unanswered questions and gaps in the field.
Background and Aims
Nonalcoholic fatty liver disease (NAFLD) affects a quarter of the adult population. A significant subset of patients are lean, but their underlying pathophysiology is not well ...understood.
Approach and Results
We investigated the role of bile acids (BAs) and the gut microbiome in the pathogenesis of lean NAFLD. BA and fibroblast growth factor (FGF) 19 levels (a surrogate for intestinal farnesoid X receptor FXR activity), patatin‐like phospholipase domain containing 3 (PNPLA3), and transmembrane 6 superfamily member 2 (TM6SF2) variants, and gut microbiota profiles in lean and nonlean NAFLD were investigated in a cohort of Caucasian patients with biopsy‐proven NAFLD (n = 538), lean healthy controls (n = 30), and experimental murine models. Patients with lean NAFLD had a more favorable metabolic and histological profile compared with those with nonlean NAFLD (P < 0.05 for all). BA levels were significantly higher in NAFLD with advanced compared with earlier stages of liver fibrosis. Patients with lean NAFLD had higher serum secondary BA and FGF19 levels and reduced 7‐alpha‐hydroxy‐4‐cholesten‐3‐one (C4) levels (P < 0.05 for all). These differences were more profound in early compared with advanced stages of fibrosis (P < 0.05 for both). Lean patients demonstrated an altered gut microbiota profile. Similar findings were demonstrated in lean and nonlean murine models of NAFLD. Treating mice with an apical sodium‐dependent BA transporter inhibitor (SC‐435) resulted in marked increases in fgf15, a shift in the BA and microbiota profiles, and improved steatohepatitis in the lean model.
Conclusions
Differences in metabolic adaptation between patients with lean and nonlean NAFLD, at least in part, explain the pathophysiology and provide options for therapy.
The mechanisms that drive nonalcoholic fatty liver disease (NAFLD) remain incompletely understood. This large multicenter study characterized the transcriptional changes that occur in liver tissue ...across the NAFLD spectrum as disease progresses to cirrhosis to identify potential circulating markers. We performed high-throughput RNA sequencing on a discovery cohort comprising histologically characterized NAFLD samples from 206 patients. Unsupervised clustering stratified NAFLD on the basis of disease activity and fibrosis stage with differences in age, aspartate aminotransferase (AST), type 2 diabetes mellitus, and carriage of
, a genetic variant associated with NAFLD. Relative to early disease, we consistently identified 25 differentially expressed genes as fibrosing steatohepatitis progressed through stages F2 to F4. This 25-gene signature was independently validated by logistic modeling in a separate replication cohort (
= 175), and an integrative analysis with publicly available single-cell RNA sequencing data elucidated the likely relative contribution of specific intrahepatic cell populations. Translating these findings to the protein level, SomaScan analysis in more than 300 NAFLD serum samples confirmed that circulating concentrations of proteins AKR1B10 and GDF15 were strongly associated with disease activity and fibrosis stage. Supporting the biological plausibility of these data, in vitro functional studies determined that endoplasmic reticulum stress up-regulated expression of
,
, and
, whereas GDF15 supplementation tempered the inflammatory response in macrophages upon lipid loading and lipopolysaccharide stimulation. This study provides insights into the pathophysiology of progressive fibrosing steatohepatitis, and proof of principle that transcriptomic changes represent potentially tractable and clinically relevant markers of disease progression.
The pandemic of obesity and its related complications is rapidly changing the epidemiology of many types of cancer, including hepatocellular carcinoma (HCC). Non-alcoholic fatty liver disease (NAFLD) ...is becoming a major cause of HCC, with a steadily rising trend compared to viral or alcohol-induced chronic hepatitis. The much greater prevalence of the underlying liver disease in the general population and the chance of HCC occurrence in non-cirrhotic liver are the most worrisome aspects of HCC in NAFLD. Effective screening programmes are currently hampered by limited knowledge of the pathways of carcinogenesis and a lack of tools able to stratify the risk of HCC in the NAFLD population. Hence, poor surveillance has prevented the development of an adequate treatment for NAFLD-related HCC. Systemic and hepatic molecular mechanisms involved in hepatocarcinogenesis, as well as potential early markers of HCC are being extensively investigated. This review describes the current clinical impact of HCC in NAFLD and discusses the most important unmet needs for its effective management.
Non-Alcoholic Fatty Liver Disease (NAFLD), a progressive liver disease that is closely associated with obesity, type 2 diabetes, hypertension and dyslipidaemia, represents an increasing global public ...health challenge. There is significant variability in the disease course: the majority exhibit only fat accumulation in the liver but a significant minority develop a necroinflammatory form of the disease (non-alcoholic steatohepatitis, NASH) that may progress to cirrhosis and hepatocellular carcinoma. At present our understanding of pathogenesis, disease natural history and long-term outcomes remain incomplete. There is a need for large, well characterised patient cohorts that may be used to address these knowledge gaps and to support the development of better biomarkers and novel therapies.
The European NAFLD Registry is an international, prospectively recruited observational cohort study that aims to establish a large, highly-phenotyped patient cohort and linked bioresource. Here we describe the infrastructure, data management and monitoring plans, and the standard operating procedures implemented to ensure the timely and systematic collection of high-quality data and samples. Already recruiting subjects at secondary/tertiary care centres across Europe, the Registry is supporting the European Union IMI2-funded LITMUS ‘Liver Investigation: Testing Marker Utility in Steatohepatitis’ consortium, which is a major international effort to robustly validate biomarkers that diagnose, risk stratify and/or monitor NAFLD progression and liver fibrosis stage. The European NAFLD Registry has the demonstrable capacity to support research and biomarker development at scale and pace.
There is an unmet need for non-invasive biomarkers in non-alcoholic fatty liver disease (NAFLD) that can diagnose advanced disease and identify patients suitable for clinical trials. The PRO-C3 ...collagen neo-epitope is a putative direct marker of fibrogenesis. We assessed the performance of PRO-C3 in a large, well-characterised international NAFLD cohort and report the development and validation of 2 novel panels for the diagnosis of advanced fibrosis (F≥3) in NAFLD, including a simplified clinical score which eliminates the need for online calculators.
Plasma PRO-C3 levels were determined in a prospectively recruited international cohort of 449 patients with biopsy diagnosed NAFLD across the full disease spectrum (F0: n = 90; F1: 100; F2: 92; F3: 101; F4: 66). The cohort was divided into a discovery group (n = 151) and a validation group (n = 298). Logistic regression was performed to establish complex (FIBC3) and simplified (ABC3D) diagnostic scores that accurately identify advanced fibrosis. Performance for each was compared to established non-invasive fibrosis scoring systems.
Plasma PRO-C3 levels correlated with grade of histological steatohepatitis (r
= 0.367,
0.0001) and stage of fibrosis (r
= 0.462,
0.0001), exhibiting similar performance to current fibrosis scores such as FIB4 for the detection of F≥3 fibrosis. FIBC3 exhibited substantially improved accuracy (AUROC 0.89 and 0.83 in the discovery and validation sets, respectively) and outperformed FIB4 and other similar diagnostic panels. The simplified version, ABC3D, was concurrently developed and had comparable diagnostic accuracy (AUROC 0.88 and 0.81 in the discovery and validation sets, respectively).
Plasma PRO-C3 levels correlate with severity of steatohepatitis and fibrosis stage. The FIBC3 panel is an accurate tool with a single threshold value that maintains both sensitivity and specificity for the identification of F≥3 fibrosis in NAFLD, eliminating indeterminate results and outperforming commonly used non-invasive tools. A greatly simplified version (ABC3D) that is readily amenable to use in the clinic has been validated and shown to perform with similar accuracy, and may prove a useful tool in routine clinical practice.
We performed a comprehensive, independent evaluation of a collagen biomarker (PRO-C3) to detect and quantify liver fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). We report the development of 2 diagnostic panels using PRO-C3 to identify patients with advanced fibrosis, one optimal but more complex to calculate (FIBC3), the other easier to use (ABC3D) whilst still performing well.
We investigated the longitudinal impact of antinuclear antibody (ANA) on clinical outcomes and survival in nonalcoholic fatty liver disease (NAFLD).
ANA were found in 16.9% of 923 biopsy-proven NAFLD ...patients, but none of them had histologic autoimmune hepatitis (AIH) or developed AIH after a mean follow-up of 106±50 months.
Although ANA-positive cases had a higher prevalence of nonalcoholic steatohepatitis at baseline, the occurrence of liver-related events, hepatocellula carcinoma, cardiovascular events, extrahepatic malignancy, and overall survival were similar to ANA-negative.
Once AIH has been ruled out, the long-term outcomes and survival are unaffected by the presence of ANA in patients with NAFLD.
In patients with inflammatory bowel diseases (IBD) undergoing biologic therapy, biomarkers of treatment response are still scarce. This study aimed to evaluate whether serum zonulin, a biomarker of ...intestinal permeability; soluble CD163 (sCD163), a macrophage activation marker; and a panel of serum cytokines could predict the response to biologic treatment in patients with IBD. For this purpose, we prospectively enrolled 101 patients with IBD and 19 patients with irritable bowel syndrome (IBS) as a control group; 60 out of 101 patients underwent treatment with biologics. Zonulin, sCD163, and cytokines were measured at the baseline in all patients and after 10 weeks of treatment in the 60 patients who underwent biologic therapy. We observed that zonulin levels were higher in IBD patients with active disease compared to those in remission (
= 0.035), and that sCD163 values were higher in patients with IBD compared to those with IBS (
= 0.042), but no association with therapy response was observed for either biomarker. Conversely, interleukin (IL)-6, IL-8, IL-10, and tumor necrosis factor-alpha showed a significant reduction from baseline to week 10 of treatment, particularly in responder patients. By multivariate logistic regression analysis corrected for disease (Crohn's disease or ulcerative colitis), type of biologic drug (Infliximab, Adalimumab, Vedolizumab, or Ustekinumab) and disease activity, the reduction in IL-6 values was associated with a clinical response at 12 months of biological therapy (odds ratio (OR) = 4.75, 95% confidence interval (CI) 1.25-18.02,
= 0.022). In conclusion, the measurement of serum IL-6 in biologics-treated IBD patients may allow for the prediction of response to treatment at 12 months of therapy and thus may help with tailoring personalized treatment strategies.
Serum microRNA (miRNA) levels are known to change in non-alcoholic fatty liver disease (NAFLD) and may serve as useful biomarkers. This study aimed to profile miRNAs comprehensively at all NAFLD ...stages.
We profiled 2,083 serum miRNAs in a discovery cohort (183 cases with NAFLD representing the complete NAFLD spectrum and 10 population controls). miRNA libraries generated by HTG EdgeSeq were sequenced by Illumina NextSeq. Selected serum miRNAs were profiled in 372 additional cases with NAFLD and 15 population controls by quantitative reverse transcriptase PCR.
Levels of 275 miRNAs differed between cases and population controls. Fewer differences were seen within individual NAFLD stages, but miR-193a-5p consistently showed increased levels in all comparisons. Relative to NAFL/non-alcoholic steatohepatitis (NASH) with mild fibrosis (stage 0/1), 3 miRNAs (miR-193a-5p, miR-378d, and miR378d) were increased in cases with NASH and clinically significant fibrosis (stages 2–4), 7 (miR193a-5p, miR-378d, miR-378e, miR-320b, miR-320c, miR-320d, and miR-320e) increased in cases with NAFLD activity score (NAS) 5–8 compared with lower NAS, and 3 (miR-193a-5p, miR-378d, and miR-378e) increased but 1 (miR-19b-3p) decreased in steatosis, activity, and fibrosis (SAF) activity score 2–4 compared with lower SAF activity. The significant findings for miR-193a-5p were replicated in the additional cohort with NAFLD. Studies in Hep G2 cells showed that following palmitic acid treatment, miR-193a-5p expression decreased significantly. Gene targets for miR-193a-5p were investigated in liver RNAseq data for a case subgroup (n = 80); liver GPX8 levels correlated positively with serum miR-193a-5p.
Serum miR-193a-5p levels correlate strongly with NAFLD activity grade and fibrosis stage. MiR-193a-5p may have a role in the hepatic response to oxidative stress and is a potential clinically tractable circulating biomarker for progressive NAFLD.
MicroRNAs (miRNAs) are small pieces of nucleic acid that may turn expression of genes on or off. These molecules can be detected in the blood circulation, and their levels in blood may change in liver disease including non-alcoholic fatty liver disease (NAFLD). To see if we could detect specific miRNA associated with advanced stages of NAFLD, we carried out miRNA sequencing in a group of 183 patients with NAFLD of varying severity together with 10 population controls. We found that a number of miRNAs showed changes, mainly increases, in serum levels but that 1 particular miRNA miR-193a-5p consistently increased. We confirmed this increase in a second group of cases with NAFLD. Measuring this miRNA in a blood sample may be a useful way to determine whether a patient has advanced NAFLD without an invasive liver biopsy.
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•Serum miRNA was sequenced in 183 NAFLD cases of varying severity and 10 population controls.•Plasma levels of miR-193a-5p were significantly increased in patients with advanced fibrosis, high NAS scores, or high SAF scores.•Other miRNAs including miR378d and miR378e were also significantly increased in certain comparisons.•The findings for miR-193a-5p were replicated in a cohort of 372 additional NAFLD cases.
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