Low-fasting triglyceride levels are associated with non-invasive markers of advanced liver fibrosis among adults in the United States

VLDL lipidomics reveals hepatocellular lipidome changes in metabolic dysfunction-associated steatotic liver disease

BACKGROUND

The production of VLDL is one of the primary mechanisms through which liver cells regulate intracellular lipid homeostasis. We hypothesize that the disease characteristics of metabolic dysfunction-associated steatotic liver disease (MASLD) differentially impact VLDL lipid composition. This study comprehensively examines the relationship between VLDL-lipidome and MASLD histology and disease-associated genetics, aiming to define MASLD-related VLDL changes.

METHODS

We performed untargeted lipidomics on serum VLDL particles in a cohort of biopsy-proven MASLD patients to examine the relationship between VLDL-lipidome and MASLD disease features as well as MASLD-related genetic variants.

RESULTS

Among 1514 detected lipid species in VLDL, triglyceride (TG), phosphatidylcholine (PC), and ceramide (Cer) were the top classes. Moderate to severe hepatic steatosis was associated an increase in VLDL-TG, especially those with palmitic acid (C16:0). A unified acyl chain distribution analysis revealed that steatosis was associated with increases in TGs with saturated and monounsaturated fatty acyl chains, but decreases in polyunsaturated fatty acyl chains, a pattern that was not mirrored in acyl chains from VLDL-PC or VLDL-Cer. Lobular inflammation was associated with reductions in lipids with polyunsaturated acyl chains, particularly docosahexaenoic acid (C22:6). Meanwhile, patients with advanced liver fibrosis (stages 3-4) had reductions in VLDL-TGs with both saturated and polyunsaturated acyl chains and overall enrichment in Cer species. Furthermore, MASLD-associated genetic variants in PNPLA3, TM6SF2, GPAM, HSD17B13, and MTARC1 demonstrated distinct VLDL-lipidomic signatures in keeping with their biology in lipoprotein metabolism.

CONCLUSIONS

Hepatic steatosis and liver fibrosis in MASLD are associated with distinct VLDL-lipidomic signatures, respectively. This relationship is further modified by MASLD-genetics, suggesting a differential impact of pathogenic features on hepatocellular lipid homeostasis.

Associations between non-insulin-based insulin resistance surrogate markers and liver-related outcomes in metabolic dysfunction-associated steatotic liver disease: a nationwide cohort study in South Korea

BACKGROUND

Insulin resistance (IR) is a crucial mechanism in the pathogenesis and clinical progression of metabolic dysfunction-associated steatotic liver disease (MASLD). This study aimed to examine the relationship between non-insulin-based IR surrogate markers and the incidence of liver-related outcomes in individuals with MASLD in a nationwide Korean cohort.

METHODS

A total of 66,334 individuals with MASLD who underwent a health examination between 1 January 2009 and 31 December 2010 were included in the study and followed until 31 December 2019, with a median follow-up period of 9.4 years. Hepatic steatosis was defined as a fatty liver index ≥ 30. The triglyceride-glucose (TyG) index, triglyceride-to-high-density lipoprotein cholesterol (TG/HDL) ratio, and metabolic score of IR (METS-IR) were employed as non-insulin-based IR surrogate markers. The MASLD groups were divided into four groups based on the non-insulin-based IR surrogate markers quartiles. The primary outcome was liver-related outcomes, as a composite of hepatocellular carcinoma and decompensated liver cirrhosis.

RESULTS

The MASLD group was 64.4% male (average age, 59.0 years). Using the lowest quartile (Q1) of the three non-insulin-based IR surrogate markers as a reference, a decrease in the adjusted hazard ratio for liver-related outcomes was observed from Q2 to Q4: (TyG: Q2 0.90 [95% confidence interval [CI]: 0.79-1.02], Q3 0.80 [95% CI: 0.70-0.91], Q4 0.80 [95% CI: 0.69-0.92]; TG/HDL: Q2 0.85 [95% CI: 0.75-0.97], Q3 0.81 [95% CI: 0.71-0.92], Q4 0.81 [95% CI: 0.71-0.93]; METS-IR: Q2 0.83 [95% CI: 0.73-0.95], Q3 0.80 [95% CI: 0.70-0.91], Q4 0.80 [95% CI: 0.70-0.92]).

CONCLUSIONS

A lower non-insulin-based IR surrogate marker in the MASLD group may be associated with an increased risk of liver-related outcomes. In the course of monitoring MASLD, metabolic alterations must be meticulously observed.

Apolipoprotein C-III in association with metabolic-dysfunction associated steatotic liver disease: A large, multicenter study

BACKGROUND & AIMS

The available literature on the effect of apolipoprotein C-III (ApoC-III) inhibition in MASLD reveals inconsistencies. The aim of the present work was to examine levels of ApoC-III in the entire spectrum of metabolic-dysfunction associated steatotic liver disease (MASLD).

METHODS

This is a multicenter study involving patients enrolled in two gastroenterology-hepatology clinics (Greece and Australia) and in a bariatric-metabolic surgery clinic (Italy), with liver biopsy before and after bariatric surgery or lifestyle modification.

RESULTS

Comparing simple MASL to steatohepatitis (MASH) with fibrosis stage F ≥ 2 (at-risk MASH), revealed a marginally significant trend for decreased ApoC-III levels in the latter group (p = 0.07). Multi-adjusted analysis revealed an inverse association between ApoC-III and at-risk MASH (Odds Ratioper 1 mg/dL increase in ApoC-III = 0.91, 95 % Confidence Interval (0.83, 0.99)). ApoC-III interacted with triglycerides in predicting at-risk MASH (p-for-interaction = 0.002). Participants with ApoC-III > median (∼3.75 mg/dL) and normal triglycerides (triglyceridese≤150 mg/dL) had the lowest likelihood to present at-risk MASH (31.8 %) in contrast with participants with ApoC-III < median and hypertriglyceridemia among whom at-risk MASH was recorded in 57.1 %. In multi-adjusted analysis participants with normal triglycerides and high ApoC-III had 64 % lower odds of at-risk MASH compared with their counterparts with ApoC-III < median (OR = 0.36, 95%CI (0.14, 0.86)). Among participants with hypertriglyceridemia, those with ApoC-III < median had less prevalent at-risk MASH compared with those with ApoC-III ≥ median (OR = 0.54, 95%CI (0.32, 0.98)); however in all cases significance was lost when liver enzymes were taken into account.

CONCLUSIONS

In advanced disease stages, ApoC-III levels seem to be decreased and advanced organ damage may be a potential explanation. Mendelian randomization studies are needed to confirm or refute this hypothesis.

Legacy and alternative per- and polyfluoroalkyl substances (PFAS) alter the lipid profile of HepaRG cells

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used in various industrial and consumer products. They have gained attention due to their ubiquitous occurrence in the environment and potential for adverse effects on human health, often linked to immune suppression, hepatotoxicity, and altered cholesterol metabolism. This study aimed to explore the impact of ten individual PFAS, 3 H-perfluoro-3-[(3-methoxypropoxy) propanoic acid] (PMPP/Adona), ammonium perfluoro-(2-methyl-3-oxahexanoate) (HFPO-DA/GenX), perfluorobutanoic acid (PFBA), perfluorobutanesulfonic acid (PFBS), perfluorodecanoic acid (PFDA), perfluorohexanoic acid (PFHxA), perfluorohexanesulfonate (PFHxS), perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), and perfluorooctanesulfonic acid (PFOS) on the lipid metabolism in human hepatocyte-like cells (HepaRG). These cells were exposed to different concentrations of PFAS ranging from 10 µM to 5000 µM. Lipids were extracted and analyzed using liquid chromatography coupled with mass spectrometry (LC- MS-QTOF). PFOS at 10 µM and PFOA at 25 µM increased the levels of ceramide (Cer), diacylglycerol (DAG), N-acylethanolamine (NAE), phosphatidylcholine (PC), and triacylglycerol (TAG) lipids, while PMPP/Adona, HFPO-DA/GenX, PFBA, PFBS, PFHxA, and PFHxS decreased the levels of these lipids. Furthermore, PFOA and PFOS markedly reduced the levels of palmitic acid (FA 16.0). The present study shows distinct concentration-dependent effects of PFAS on various lipid species, shedding light on the implications of PFAS for essential cellular functions. Our study revealed that the investigated legacy PFAS (PFOS, PFOA, PFBA, PFDA, PFHxA, PFHxS, and PFNA) and alternative PFAS (PMPP/Adona, HFPO-DA/GenX and PFBS) can potentially disrupt lipid homeostasis and metabolism in hepatic cells. This research offers a comprehensive insight into the impacts of legacy and alternative PFAS on lipid composition in HepaRG cells.

High-Fructose/High-Fat Diet Downregulates the Hepatic Mitochondrial Oxidative Phosphorylation Pathway in Mice Compared with High-Fat Diet Alone

Both high-fat diet (HFD) alone and high-fructose plus HFD (HFr/HFD) cause diet-induced non-alcoholic fatty liver disease in murine models. However, the mechanisms underlying their impacts on inducing different levels of liver injury are yet to be elucidated. This study employed a proteomic approach to elucidate further on this issue. Adult male C57BL/6J mice were allocated to the HFD or the HFr/HFD group. After feeding for 12 weeks, all mice were euthanized and samples were collected. The proteomic profiles in liver tissues were analyzed using liquid chromatography-tandem mass spectrometry followed by canonical pathway analysis. We demonstrated that the mitochondrial oxidative phosphorylation (OXPHOS) pathway was the most significantly downregulated canonical pathway in the HFr/HFD group when compared with the HFD group. Within the OXPHOS pathway, the HFr/HFD group demonstrated significant downregulation of complexes I and III and significant upregulation of complex IV when compared with the HFD group. Moreover, the HFr/HFD group had lower protein levels of NADH: ubiquinone oxidoreductase subunits S3, S6, A5, and A12 in complex I (p < 0.001, =0.03, <0.001, and <0.001, respectively), lower protein level of cytochrome C in complex III (p < 0.001), and higher protein level of cytochrome C oxidase subunit 2 in complex IV (p = 0.002), when compared with the HFD group. To summarize, we have demonstrated that the hepatic mitochondrial OXPHOS pathway is significantly downregulated in long-term HFr/HFD feeding when compared with long-term HFD feeding. These data support the concept that the hepatic mitochondrial OXPHOS pathway should be involved in mediating the effects of HFr/HFD on inducing more severe liver injury than HFD alone.

Sex-specific changes in triglyceride profiles in liver cirrhosis and hepatitis C virus infection

Background

Hepatitis C virus (HCV) infection is associated with serum lipid abnormalities, which partly normalize following direct-acting antiviral (DAA) therapy. Here, associations of serum triglycerides (TGs) with viral genotype and markers of liver disease severity were evaluated in patients with chronic HCV. 

Methods

The study included the serum of 177 patients with chronic HCV. TGs were quantified by flow injection analysis Fourier transform mass spectrometry. Laboratory values and noninvasive scores for liver fibrosis assessment were determined. The nonparametric Kruskal‒Wallis test, one-way ANOVA, multiple linear regression and Student’s t test were used as appropriate. P values were adjusted for multiple comparisons.

Results

HCV-infected women had lower serum TGs than men, and thus, a sex-specific analysis was performed. None of the 46 TG species analyzed differed in the serum of female patients with and without liver cirrhosis. In contrast, in the serum of male patients with liver cirrhosis, TGs with 53, 56 and 58 carbon atoms and three to eight double bonds were diminished. These polyunsaturated TGs were also low in males with a high fibrosis-4 score. TGs with 7 or 8 double bonds negatively correlated with the model of end-stage liver disease score in males. In addition, TGs with 49, 51 and 53 carbon atoms were reduced in male patients infected with genotype 3a in comparison to genotype 1a. TGs with 56 carbon atoms were lower in genotype 3a-infected males than in genotype 1b-infected males. TGs did not differ in females by genotype. Genotype 3-related changes disappeared at the end of therapy with DAAs. Overall, the levels of serum TGs did not change during DAA therapy in either sex. Consequently, the serum TGs of males with liver cirrhosis were lower than those of males without cirrhosis at the end of therapy. Such a difference was not apparent in females.

Conclusions

The decline in TGs observed only in male patients with liver cirrhosis and male patients infected with genotype 3 illustrates sex-specific changes in lipid metabolism in chronic HCV.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01715-w.

Metabolic Score for Insulin Resistance Is Inversely Related to Incident Advanced Liver Fibrosis in Patients with Non-Alcoholic Fatty Liver Disease

We determined the relationships between metabolic score for IR (METS-IR), triglyceride-glucose (TyG) index, and homeostatic model assessment for IR (HOMA-IR) and incident advanced liver fibrosis (ALF) and assessed the abilities of the three IR indicators to predict ALF in patients with non-alcoholic fatty liver disease (NAFLD) in adults with NAFLD who were aged 40–69 years old. Among 2218 participants with NAFLD at baseline, the areas under the receiver operating characteristic curve for predicting ALF of the METS-IR was 0.744 (0.679–0.810), significantly higher than that of TyG index (0.644 (0.569–0.720)) or that of HOMA-IR (0.633 (0.556–0.710)). Among 1368 patients with NAFLD and without ALF at baseline, 260 (19.0%) patients with NAFLD progressed to ALF during the 16-year follow-up period. Multivariable Cox proportional hazard regression analysis revealed that the adjusted hazard ratio (95% confidence interval) for incident ALF in the highest tertiles of METS-IR, TyG index, and HOMA-IR compared with the lowest tertile of each IR indicator were 0.5 (0.36–0.91), 0.7 (0.49–1.00), and 1.01 (0.71–1.42), respectively. METS-IR was inversely associated with ALF in patients with NAFLD, which cautiously suggests that the risk of ALF may need to be evaluated when metabolic parameters improve in individuals with NAFLD.

Cumulative Betel Quid Chewing and the Risk of Significant Liver Fibrosis in Subjects With and Without Metabolic Syndrome

BACKGROUND

Betel quid chewing is associated with metabolic disorders, oral cancer, cardiovascular disease, and chronic liver diseases. Metabolic syndrome (MetS) is also a factor associated with liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). However, studies on the relationship between betel quid and liver fibrosis while also considering MetS are lacking. The aim of this study was thus to investigate the association of betel quid chewing and liver fibrosis with MetS.

METHODS

A total of 9,221 subjects were enrolled after excluding subjects <18 years of age, with past history of chronic liver diseases, cancer, significant alcohol consumption, and incomplete data. Betel nut chewing habit was classified into three groups: none, former-chewing, and current-chewing, and cumulative exposure was calculated by multiplying the duration with the quantity. Liver fibrosis was evaluated based on the NAFLD fibrosis score (NFS), which is a composite score of age, hyperglycemia, BMI, platelet count, albumin, and the AST/ALT ratio. Significant liver fibrosis was defined as NFS ≥-1.455.

RESULTS

After adjusting for other variables, MetS was positively associated with significant liver fibrosis. Subjects with both MetS and betel quid chewing had a higher associated risk of significant liver fibrosis than those with neither MetS nor betel quid chewing (adjusted OR: 3.03, 95% CI: 2.04-4.50, p < 0.001). Betel quid chewing was associated with significant liver fibrosis (adjusted OR: 2.00, 95% CI: 1.14-3.49, p = 0.015) in subjects with MetS, but not in subjects without.

CONCLUSION

Metabolic syndrome increased the associated risk of significant liver fibrosis. Cumulative betel quid exposure increased the associated risk of significant liver fibrosis in subjects with MetS, but not in subjects without.

Metabolic-associated fatty liver disease and lipoprotein metabolism

BACKGROUND

Non-alcoholic fatty liver disease, or as recently proposed 'metabolic-associated fatty liver disease' (MAFLD), is characterized by pathological accumulation of triglycerides and other lipids in hepatocytes. This common disease can progress from simple steatosis to steatohepatitis, and eventually end-stage liver diseases. MAFLD is closely related to disturbances in systemic energy metabolism, including insulin resistance and atherogenic dyslipidemia.

SCOPE OF REVIEW

The liver is the central organ in lipid metabolism by secreting very low density lipoproteins (VLDL) and, on the other hand, by internalizing fatty acids and lipoproteins. This review article discusses recent research addressing hepatic lipid synthesis, VLDL production, and lipoprotein internalization as well as the lipid exchange between adipose tissue and the liver in the context of MAFLD.

MAJOR CONCLUSIONS

Liver steatosis in MAFLD is triggered by excessive hepatic triglyceride synthesis utilizing fatty acids derived from white adipose tissue (WAT), de novo lipogenesis (DNL) and endocytosed remnants of triglyceride-rich lipoproteins. In consequence of high hepatic lipid content, VLDL secretion is enhanced, which is the primary cause of complex dyslipidemia typical for subjects with MAFLD. Interventions reducing VLDL secretory capacity attenuate dyslipidemia while they exacerbate MAFLD, indicating that the balance of lipid storage versus secretion in hepatocytes is a critical parameter determining disease outcome. Proof of concept studies have shown that promoting lipid storage and energy combustion in adipose tissues reduces hepatic lipid load and thus ameliorates MAFLD. Moreover, hepatocellular triglyceride synthesis from DNL and WAT-derived fatty acids can be targeted to treat MAFLD. However, more research is needed to understand how individual transporters, enzymes, and their isoforms affect steatosis and dyslipidemia in vivo, and whether these two aspects of MAFLD can be selectively treated. Processing of cholesterol-enriched lipoproteins appears less important for steatosis. It may, however, modulate inflammation and consequently MAFLD progression.

African Americans have a distinct clinical and histologic profile with lower prevalence of NASH and advanced fibrosis relative to Caucasians

BACKGROUND AND AIMS

Racial/ethnic disparities have been reported in the prevalence of nonalcoholic fatty liver disease (NAFLD). Thus, we aimed to understand the inter-ethnic clinical, biochemical, and histological differences in a large cohort of Caucasians and African-Americans (AA).

METHODS

Laboratory and liver biopsy data of 942 NAFLD patients were retrospectively analyzed. Nine hundred seven patients were included in the analysis: 677 (74.6%) Caucasians and 230 (25.3%) AA.

RESULTS

AA had higher mean BMI compared to Caucasians (42.6 ± 9.5 vs. 39 ± 8.6 kg/m2). The prevalence of nonalcoholic steatohepatitis (NASH), defined by NAFLD activity score (NAS . 5), was higher in the Caucasians (n = 67) compared to AA (n = 7) (9.8% vs. 3%, P = 0.0007). One hundred fifteen patients (12.8%) had advanced fibrosis: 109 (16.2%) Caucasians and six (2.6%) AA. No AA patients had stage 4 fibrosis or cirrhosis. Multivariate logistic regression analysis revealed advanced fibrosis was significantly associated with age at liver biopsy (OR 1.03, 95% CI 1.0.1.1, P = 0.017, lower platelet count (OR 0.99, 95% CI 0.98.0.99, P = <0.0001), AST/ALT ratio (OR 5.19, 95% CI 2.9.9.2, P <0.0001) and Caucasian race (OR 7.49, 95% CI 2.53.22.2, P = 0.0003). Advanced fibrosis in AA was predicted by lower platelet count and AST/ALT ratio. Whereas Advanced fibrosis in Caucasians was predicted by age at biopsy, lower platelet count and AST/ALT ratio.

CONCLUSION

The AA have a distinct clinical and histologic phenotype. Caucasians have a significantly greater proportion of NASH and are eight times more likely to develop advanced fibrosis than AA.

Effectiveness and safety of obeticholic acid in a Southern European multicentre cohort of patients with primary biliary cholangitis and suboptimal response to ursodeoxycholic acid

BACKGROUND

Obeticholic acid (OCA) was recently approved as the only on-label alternative for patients with primary biliary cholangitis (PBC) with intolerance or suboptimal response to ursodeoxycholic acid (UDCA). However, few data are available outside clinical trials.

AIM

To assess the effectiveness and safety of OCA in a real-world cohort of patients with non-effective UDCA therapy.

METHODS

Open-label, prospective, real-world, multicentre study, enrolling consecutive patients who did not meet Paris II criteria, from 18 institutions in Spain and Portugal. Effectiveness was assessed by the changes in GLOBE and UK-PBC scores from baseline. POISE and Paris II criteria were evaluated after 12 months of OCA . Liver fibrosis was evaluated by FIB-4 and AST to platelet ratio index (APRI).

RESULTS

One hundred and twenty patients were eligible, median time since PBC diagnosis 9.3 (4.0-13.8) years, 21.7% had cirrhosis, and 26.7% received had previous or concomitant treatment with fibrates. Seventy-eight patients completed at least 1 year of OCA. The Globe-PBC score decreased to 0.17 (95% CI 0.05 to 0.28; P = 0.005) and the UK-PBC score decreased to 0.81 (95% CI -0.19 to 1.80; P = 0.11). There was a significant decrease in alkaline phosphatase of 81.3 U/L (95% CI 42.5 to 120; P < 0.001), ALT 22.1 U/L (95% CI 10.4 to 33.8; P < 0.001) and bilirubin 0.12 mg/dL (95% CI 0 to 0.24; P = 0.044). FIB-4 and APRI remained stable. According to the POISE criteria, 29.5% (23 out of 78) achieved response. The adverse events rate was 35%; 11.67% discontinued (8.3% due to pruritus).

CONCLUSIONS

This study supports data from phase III trials with significant improvement of PBC-Globe continuous prognostic marker score among OCA-treated patients with good tolerability.

Associations among liver disease, serum lipid profile, body mass index, ketonuria, meal skipping, and the alcohol dehydrogenase-1B and aldehyde dehydrogenase-2 genotypes in Japanese men with alcohol dependence

AIM

To elucidate associations among liver disease, lipid profile, body mass index (BMI), ketonuria, and meal skipping under the influence of alcohol dehydrogenase-1B (ADH1B; rs1229984) and aldehyde dehydrogenase-2 (ALDH2; rs671) genotypes in men with alcohol dependence.

METHODS

We investigated the associations among these variables in 1768 Japanese men with alcohol dependence. Serum lipid levels were followed up after abstinence.

RESULTS

The slow-metabolizing ADH1B Arg/Arg genotype and inactive ALDH2 Glu/Lys genotype increased the age- and drinking-adjusted odds ratio or regression coefficient for fatty liver, ketonuria, and serum high-density-lipoprotein cholesterol levels (HDL-C), and decreased these for cirrhosis and serum triglyceride levels (TG). The ADH1B Arg/Arg genotype increased the adjusted regression coefficient for BMI and non-HDL-C. In addition to the positive interlinkage among fatty liver, BMI, and atherogenic dyslipidemia, positive associations were observed of fatty liver with ketonuria and meal skipping, of cirrhosis with the BMI, and of ketonuria with non-HDL-C. Negative associations were observed of cirrhosis with fatty liver, TG, non-HDL-C, and HDL-C, and of ketonuria with BMI and TG. Overall, after admission for 4 or 6 weeks, the TG and HDL-C decreased, and the serum low-density lipoprotein cholesterol levels increased. However, there was no change of the serum low-density lipoprotein in the patients with cirrhosis or of the serum TG in those with fatty liver.

CONCLUSIONS

These associations and the alterations in lipid profile after abstinence serve as useful information for a better understanding of the clinical features of men with alcohol dependence.

Older age and HDL-cholesterol as independent predictors of liver fibrosis assessed by BARD score

BACKGROUND

It is known that non-alcoholic fatty liver disease (NAFLD), and in particular non-alcoholic steatohepatitis, can progress to advanced fibrosis. However, pathophysiological mechanisms implicated in this evolution are not elucidated yet. We aimed to investigate the independent predictors of liver fibrosis in patients with NAFLD, determined by BARD score, one of the most used algorithms for fibrosis evaluation.

METHODS

This prospective study enrolled a total of 301 participants with NAFLD, as determined by a Fatty Liver Index (FLI) ≥60. All patients were categorized into two groups: with no/mild fibrosis (BARD score 1, N.=62) and with advanced fibrosis (BARD score 2, 3 and 4 N.=239).

RESULTS

Serum high density lipoprotein cholesterol (HDL-c), glucose and glycated hemoglobin were higher (P=0.028, P<0.001 and P=0.002, respectively), whereas serum transaminases and gamma glutamil transferase levels were lower in patients with advanced fibrosis than in those with no/mild fibrosis (P=0.010, P<0.001 and P=0.005, respectively). There were no significant differences in oxidative stress (i.e., advanced oxidant protein products and malondialdehyde) and anti-oxidative protection markers (i.e., catalase) between patients with no/mild fibrosis and advanced fibrosis. Multivariate ordinal regression analysis showed independent associations and predictions of ages (OR=1.071, 95% CI 1.004-1.097, P<0.001), and HDL-c levels (OR=2.549, 95% CI 1.087-5.989, P=0.032) on BARD score categories in patients with NAFLD.

CONCLUSIONS

In conclusion, we found that older age and higher HDL-c, are independent predictors for advanced liver fibrosis assessed with the BARD score. Future investigations are needed to further explore this relationship.

Lipoprotein metabolism in liver diseases

PURPOSE OF REVIEW

The liver is the central hub of lipoprotein metabolism. A complex relationship exists between dyslipidemia and chronic liver diseases (CLDs). Recent advances in the genetics of nonalcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD) exemplify the pivotal role of lipoprotein metabolism in the pathogenesis of CLD. We review these relationships in four quintessential forms of CLD: NAFLD, ALD, cholestatic liver disease and cirrhosis, with a focus on recent discoveries.

RECENT FINDINGS

An I148 M variant in patatin-like phospholipase domain-containing protein 3 (PNPLA3) and an E167K variant in transmembrane 6 superfamily 2 (TM6SF2) are major genetic risk factors for the development and progression of NAFLD. These genetic variants also increase the risk of ALD. Both PNPLA3 and TM6SF2 are involved in the hepatic assembly of very low-density lipoprotein. The discovery of these two genetic variants highlights the risk of CLD when environmental factors are combined with functional modifications in the lipoprotein metabolism pathway.

SUMMARY

The relationship between CLD and lipoprotein metabolism is reciprocal. On the one hand, the progression of CLD impairs lipoprotein metabolism; on the other hand, modifications in lipoprotein metabolism can substantially increase the risk of CLD. These relationships are at play among the most common forms of CLD affecting a significant proportion of the population.

Genetic Determinants of Circulating Lipoproteins in Nonalcoholic Fatty Liver Disease

BACKGROUND

Recent genome-wide association studies have identified 2 genetic polymorphisms in association with nonalcoholic fatty liver disease (NAFLD): patatin-like phospholipase domain containing 3 (PNPLA3) and transmembrane 6 superfamily member 2 (TM6SF2), both of which appear to influence the production of very low density lipoprotein (VLDL). The impact of these genetic variations on lipoprotein metabolism in the setting of nonalcoholic steatohepatitis and liver fibrosis are not fully characterized.

MATERIALS AND METHODS

We measured comprehensive lipoprotein profiles by nuclear magnetic resonance among 170 serially recruited patients in an NAFLD registry, and determined their relationships with PNPLA3 and TM6SF2 genotypes.

RESULTS

In this cohort, 72% patients had at least 1 allele of either PNPLA3 I148M or TM6SF2 E167K, and 30% carried 2 alleles. In multivariate models adjusting for histologic features of nonalcoholic steatohepatitis and liver fibrosis, PNPLA3 I148M is associated with a decrease in VLDL particle size. Both PNPLA3 I148M and TM6SF2 E167K genotypes were associated with increases in the size of low density lipoprotein (LDL) and high density lipoprotein particles, phenotypes considered atheroprotective. When adjusted for both genotypes, NAFLD activity score, in particular the degree of hepatic steatosis was strongly associated with increases in the size of VLDL particles, the concentration of LDL, especially small LDL particles, and a decrease in the size of high density lipoprotein particles, all of which are linked with a proatherogenic phenotype.

CONCLUSIONS

PNPLA3 and TM6SF2 are common genetic variants among NAFLD patients and impact lipoprotein profiles in slightly different ways. The interactions between genotypes, hepatic steatosis, and lipoprotein metabolism shed lights on the pathophysiology of NAFLD, and provide opportunities for personalized treatment in the era of emerging NAFLD therapeutics.

Nonalcoholic fatty liver disease associated with metabolic syndrome: Influence of liver fibrosis stages on characteristics of very low-density lipoproteins

BACKGROUND

We evaluated possible changes in VLDLcharacteristics, and metabolic related factors, in MetS-associated NAFLD and accompanying liver fibrosis.

METHODS

We studied 36 MetS patients with biopsy-proven NAFLD (MetS+NAFLD) and 24 MetS without ultrasound NAFLD evidence. Further, MetS+NAFLD was sub-divided according to fibrosis stage into, non-to-moderate (F0-F2, n=27) and severe (F3-F4, n=9) fibrosis. We measured: lipid profile, VLDL composition and size (size exclusion-HPLC), CETP and lipoprotein lipase (LPL) activities and adiponectin. Additionally, in MetS+NAFLD type IV collagen 7S domain was measured.

RESULTS

MetS+NAFLD showed increased VLDL-mass, VLDL particle number, VLDL-triglyceride% and large VLDL-% (p<0.04). CETP activity tended to increase in MetS+NAFLD (p=0.058), while LPL activity was unchanged. Moreover, in MetS+NAFLD, adiponectin was decreased (p<0.001), and negatively correlated with VLDL-mass and VLDL particle number (p<0.05), independently of insulin-resistance. Within MetS+NAFLD group, despite greater insulin-resistance, patients with severe fibrosis showed lower plasma triglycerides, VLDL-mass, VLDL-triglyceride%, large VLDL-% and CETP activity (p<0.05), while type IV collagen was increased (p=0.009) and inversely correlated with large VLDL-% (p=0.045).

CONCLUSIONS

In MetS, NAFLD is associated with larger and triglyceride over-enriched circulating VLDLs, of greater atherogenicity. However, when NAFLD progresses to severe fibrosis, circulating VLDL features apparently improved, probably due to early alterations in hepatic synthetic function.

Infrared analysis of lipoproteins in the detection of alcohol biomarkers

Background:

Alcoholism is a major public health problem. Alcohol causes modifications in the composition and concentration of lipoproteins and influences the enzymes and transfer proteins that transform lipoproteins in plasma. Alcohol is associated with the presence of alcohol biomarkers (fatty acid ethyl esters [FAEEs] and phosphatidylethanol [PEth]) in lipoproteins. We explore the possibilities of detecting alcohol biomarkers in non-high-density-lipoproteins (non-HDLs) precipitated from serum using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR).

Methods:

Analyzes were carried out on stored serum samples, with known % carbohydrate-deficient transferrin (CDT) values, included in a driver’s license regranting program under the control of the Belgian Institute of Road Safety. The study consisted of 127 control samples (CDT≤1.3%) and 114 alcoholic samples (CDT>1.3%). Liver enzymes, CRP, triglycerides, total, HDL- and LDL-cholesterol values were determined. Non-HDLs were precipitated with sodium phosphotungstate and MgCl2 and analyzed using ATR-FTIR in the range from 4500 cm−1 to 450 cm−1 using a Perkin Elmer ATR-FTIR Spectrometer Two.

Results:

The area under the curve of the 1130–990 cm−1 region (AUC1130−990 cm−1) was able to discriminate controls from alcoholics (p<0.0001) due to the presence of FAEEs in lipoproteins. Multiple regression analysis significantly predicted the AUC1130−990 cm−1 (adj. r2=0.13, p<0.0001). Significant correlations were found between AUC1130−990 cm−1 and CDT values (r=0.32, p<0.0001), AST/ALT ratio (r=0.21, p=0.001). GGT showed no significant correlation.

Conclusions:

Infrared analysis of lipoproteins is a potential tool in the detection of alcohol biomarkers.

Steatohepatitis and liver fibrosis are predicted by the characteristics of very low density lipoprotein in nonalcoholic fatty liver disease

BACKGROUND & AIMS

A major challenge in the management of nonalcoholic fatty liver disease (NAFLD) is to identify patients with nonalcoholic steatohepatitis (NASH) and early liver fibrosis. The progression of NAFLD is accompanied by distinctive changes in very low density lipoprotein (VLDL), a lipoprotein particle produced exclusively in the liver. Herein, we sought to determine the characteristics of VLDL profiles associated with NASH and liver fibrosis.

METHODS

We evaluated VLDL profiles of 128 patients from a single centre NAFLD registry, and examined VLDL size, total and subclass VLDL concentrations in relation to NAFLD activity score (NAS), steatohepatitis and liver fibrosis as determined by liver biopsy.

RESULTS

A near linear relationship was observed between mean VLDL particle size and NAFLD activity score (NAS). In multivariate models, VLDL particle size was significantly associated with both NAS and NASH, after adjustment for BMI and diabetes. A decrease in small VLDL particle concentration was associated with more advanced liver fibrosis. In receiver operative characteristic analyses, mean VLDL size performed similarly to cytokeratin 18 in predicting NASH, whereas small VLDL particle concentration had similar performance to NAFLD fibrosis score in predicting stage 2 or above liver fibrosis.

CONCLUSIONS

The increase in mean VLDL size in NASH and decrease in small VLDL particle concentration in liver fibrosis likely reflect changes in the number and state of hepatocytes associated with NASH and fibrosis. In addition to its value in risk stratification of cardiovascular diseases, circulating VLDL profile may provide information for the staging of NAFLD disease severity.

Aspirin use is associated with lower indices of liver fibrosis among adults in the United States

BACKGROUND

Recent animal studies have shown that platelets directly activate hepatic stellate cells to promote liver fibrosis, whereas anti-platelet agents decrease liver fibrosis. It is unknown whether platelet inhibition by aspirin prevents liver fibrosis in humans.

AIM

To examine the association between aspirin use and liver fibrosis among adults with suspected chronic liver disease.

METHODS

We conducted a cross-sectional analysis using data from the National Health and Nutrition Examination Survey III. We identified 1856 individuals with suspected chronic liver disease (CLD). The degree of liver fibrosis was determined using four validated fibrosis indices and a composite index.

RESULTS

The use of aspirin was associated with a significantly lower composite liver fibrosis index calculated from FIB4, APRI, Forns and NFS [0.24 standard deviation (s.d.) units lower; 95% CI -0.42 to -0.06, P = 0.009]. The association of aspirin with lower fibrosis scores was significantly larger among those with suspected CLD compared to those without (-0.23 vs. -0.03 s.d. units; P interaction = 0.05). The negative association between aspirin use and lower fibrosis index was consistent across all four fibrosis indices (P = 0.002-0.08) in individuals with chronic viral hepatitis, suspected alcoholic liver disease and NASH. In comparison, no negative associations with liver fibrosis were seen with ibuprofen in parallel analyses.

CONCLUSIONS

The use of aspirin was associated with significantly lower indices of liver fibrosis among US adults with suspected chronic liver diseases. Aspirin and other anti-platelet drugs warrant further investigation for the prevention and treatment of liver fibrosis.

Associations of insulin resistance, inflammation and liver synthetic function with very low-density lipoprotein: The Cardiovascular Health Study

INTRODUCTION

Production of very low-density lipoprotein (VLDL) is increased in states of metabolic syndrome, leading to hypertriglyceridemia. However, metabolic syndrome is often associated with non-alcoholic fatty liver disease, which leads to liver fibrosis and inflammation that may decrease VLDL production. In this study, we aim to determine the interactive impact on VLDL profiles from insulin resistance, impairment in liver synthetic function and inflammation.

METHODS

We examined cross-sectional associations of insulin sensitivity, inflammation, and liver synthetic function with VLDL particle (VLDL-P) concentration and size among 1,850 older adults in the Cardiovascular Health Study.

RESULTS

Indices for high insulin sensitivity and low liver synthetic function were associated with lower concentrations of VLDL-P. In addition, insulin resistance preferentially increased concentration of large VLDL and was associated with mean VLDL size. Indices for inflammation however demonstrated a nonlinear relationship with both VLDL-P concentration and VLDL size. When mutually adjusted, one standard deviation (SD) increment in Matsuda index and C-reactive protein (CRP) were associated with 4.9 nmol/L (-8.2 to -1.5, p=0.005) and 6.3 nmol/L (-11.0 to -1.6, p=0.009) lower VLDL-P concentration respectively. In contrast, one-SD increment in factor VII, a marker for liver synthetic function, was associated with 16.9 nmol/L (12.6-21.2, p<0.001) higher VLDL-P concentration. Furthermore, a one-SD increment in the Matsuda index was associated with 1.1 nm (-2.0 to -0.3, p=0.006) smaller mean VLDL size, whereas CRP and factor VII were not associated with VLDL size.

CONCLUSION

Insulin sensitivity, inflammation and markers for liver synthetic function differentially impact VLDL-P concentration and VLDL size. These results underscore the complex effects of insulin resistance and its complications on VLDL production.