Sirtuin3 promotes the degradation of hepatic Z alpha-1 antitrypsin through lipophagy

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is a genetic disease caused by misfolding and accumulation of mutant alpha-1 antitrypsin (ZAAT) in the endoplasmic reticulum of hepatocytes. Hepatic ZAAT aggregates acquire a toxic gain-of-function that impacts the endoplasmic reticulum which is theorized to cause liver disease in individuals with AATD who present asymptomatic until late-stage cirrhosis. Currently, there is no treatment for AATD-mediated liver disease except liver transplantation. In our study of mitochondrial RNA, we identified that Sirtuin3 (SIRT3) plays a role in the hepatic phenotype of AATD.

METHODS

Utilizing RNA and protein analysis in an in vitro AATD model, we investigated the role of SIRT3 in the pathophysiology of AATD-mediated liver disease while also characterizing our novel, transgenic AATD mouse model.

RESULTS

We show lower expression of SIRT3 in ZAAT-expressing hepatocytes. In contrast, the overexpression of SIRT3 increases hepatic ZAAT degradation. ZAAT degradation mediated by SIRT3 appeared independent of proteasomal degradation and regular autophagy pathways. We observed that ZAAT-expressing hepatocytes have aberrant accumulation of lipid droplets, with ZAAT polymers localizing on the lipid droplet surface in a direct interaction with Perilipin2, which coats intracellular lipid droplets. SIRT3 overexpression also induced the degradation of lipid droplets in ZAAT-expressing hepatocytes. We observed that SIRT3 overexpression induces lipophagy by enhancing the interaction of Perilipin2 with HSC70. ZAAT polymers then degrade as a consequence of the mobilization of lipids through this process.

CONCLUSIONS

In this context, SIRT3 activation may eliminate the hepatic toxic gain-of-function associated with the polymerization of ZAAT, providing a rationale for a potential novel therapeutic approach to the treatment of AATD-mediated liver disease.

Meta-analysis: Prevalence of significant or advanced fibrosis in adults with alpha-1-antitrypsin deficiency

BACKGROUND

The prevalence of liver fibrosis detected by non-invasive imaging in alpha-1-antitrypsin (AAT) deficiency has not been systematically assessed.

AIMS

We conducted a systematic review and meta-analysis to determine the prevalence of significant fibrosis and advanced fibrosis in AAT deficiency based on non-invasive imaging.

METHODS

Medline and Embase electronic databases were searched for studies from inception to 13 November 2022 that provided data for the prevalence of fibrosis in adults with AAT deficiency. A generalised linear mixed model with Clopper-Pearson intervals was used to pool single-arm outcomes.

RESULTS

Of the 214 records identified, 8 studies were included. Five studies assessed fibrosis using vibration-controlled transient elastography. The prevalence of significant fibrosis (defined as ≥7.1 kPA) in Z homozygosity, Z heterozygosity and non-carrier status was 22.10% (five studies, 95% CI: 17.07-28.12), 9.24% (three studies, 95% CI: 4.68-17.45) and 5.38% (one study, 95% CI: 3.27-8.73), respectively, p < 0.0001, and the prevalence of advanced fibrosis (defined as ≥9.5 kPa) was 8.13% (five studies, 95% CI: 4.60-13.96), 2.96% (three studies, 95% CI: 1.49-5.81) and 1.08% (one study, 95% CI: 0.35-3.28), respectively, p = 0.003. There were limited data regarding the use of magnetic resonance elastography or acoustic radiation force impulse to assess for fibrosis.

CONCLUSION

More than one in five adult individuals with AAT deficiency and Z homozygosity harbour significant fibrosis, and nearly 1 in 10 harbours advanced fibrosis. The risk of fibrosis increases incrementally with the frequency of Pi*Z mutations.

Performance of Plasma Biomarkers and Diagnostic Panels for Nonalcoholic Steatohepatitis and Advanced Fibrosis in Patients With Type 2 Diabetes

OBJECTIVE

The 2019 Standards of Medical Care in Diabetes suggested that patients with nonalcoholic fatty liver disease (NAFLD) should be evaluated for liver fibrosis. However, the performance of noninvasive clinical models/scores and plasma biomarkers for the diagnosis of nonalcoholic steatohepatitis (NASH) and advanced fibrosis has not been carefully assessed in patients with type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

In this cross-sectional study, patients (n = 213) had a liver MRS, and those with a diagnosis of NAFLD underwent a percutaneous liver biopsy. Several noninvasive clinical models/scores and plasma biomarkers were measured to identify NASH and advanced fibrosis (NASH: ALT, cytokeratin-18, NashTest 2, HAIR, BARD, and OWLiver; advanced fibrosis: AST, fragments of propeptide of type III procollagen [PRO-C3], FIB-4, APRI, NAFLD fibrosis score, and FibroTest).

RESULTS

None of the noninvasive tools assessed for the diagnosis of NASH in patients with T2DM had an optimum performance (all areas under the curve [AUCs] <0.80). Of note, none of the panels or biomarkers was able to outperform plasma ALT (AUC 0.78 [95% CI 0.71-0.84]). Performance was better to diagnose advanced fibrosis, in which plasma PRO-C3, AST, and APRI showed better results than the other approaches (AUC 0.90 [0.85-0.95], 0.85 [0.80-0.91], and 0.86 [0.80-0.91], respectively). Again, none of the approaches did significantly better than plasma AST. Sequential use of plasma AST and other noninvasive tests may help in limiting the number of liver biopsies required to identify patients with advanced fibrosis.

CONCLUSIONS

Performance of noninvasive clinical models/scores and plasma biomarkers for the diagnosis of NASH or advanced fibrosis was suboptimal in patients with T2DM. Combination of multiple tests may provide an alternative to minimize the need for liver biopsies to detect fibrosis in these patients.

Alpha-1 Antitrypsin Deficiency Liver Disease, Mutational Homogeneity Modulated by Epigenetic Heterogeneity With Links to Obesity

Alpha-1 antitrypsin deficiency (AATD) liver disease is characterized by marked heterogeneity in presentation and progression, despite a common underlying gene mutation, strongly suggesting the involvement of other genetic and/or epigenetic modifiers. Variation in clinical phenotype has added to the challenge of detection, diagnosis, and testing of new therapies in patients with AATD. We examined the contribution of DNA methylation (5-methylcytosine [5mC]) to AATD liver disease heterogeneity because 5mC responds to environmental and genetic cues and its deregulation is a major driver of liver disease. Using liver biopsies from adults with early-stage AATD and the ZZ genotype, genome-wide 5mC patterns were interrogated. We compared DNA methylation among patients with early AATD, and among patients with normal liver, cirrhosis, and hepatocellular carcinoma derived from multiple etiologic exposures, and linked patient clinical/demographic features. Global analysis revealed significant genomic hypomethylation in AATD liver-impacting genes related to liver cancer, cell cycle, and fibrosis, as well as key regulatory molecules influencing growth, migration, and immune function. Further analysis indicated that 5mC changes are localized, with hypermethylation occurring within a background of genome-wide 5mC loss and with patients with AATD manifesting distinct epigenetic landscapes despite their mutational homogeneity. By integrating clinical data with 5mC landscapes, we observed that CpGs differentially methylated among patients with AATD disease are linked to hallmark clinical features of AATD (e.g., hepatocyte degeneration and polymer accumulation) and further reveal links to well-known sex-specific effects of liver disease progression. Conclusion: Our data reveal molecular epigenetic signatures within this mutationally homogeneous group that point to ways to stratify patients for liver disease risk.

Clinical and histologic features of adults with alpha-1 antitrypsin deficiency in a non-cirrhotic cohort

BACKGROUND & AIMS

Alpha-1 antitrypsin deficiency (AATD) is an uncommonly recognized cause of liver disease in adults, with descriptions of its natural history limited to case series and patient-reported data from disease registries. Liver pathology is limited to selected patients or unavailable. Therefore, we aimed to determine the prevalence and severity of liver fibrosis in an adult AATD population who were not known to have cirrhosis, while defining risk factors for fibrosis and testing non-invasive markers of disease.

METHODS

A total of 94 adults with classic genotype 'PI*ZZ' AATD were recruited from North America and prospectively enrolled in the study. Liver aminotransferases and markers of synthetic function, transient elastography, and liver biopsy were performed.

RESULTS

The prevalence of clinically significant liver fibrosis (F ≥ 2) was 35.1%. Alanine aminotransferase, aspartate aminotransferase and gamma-glutamyltransferase values were higher in the F ≥ 2 group. Metabolic syndrome was associated with the presence of clinically significant fibrosis (OR 14.2; 95% CI 3.7-55; p <0.001). Additionally, the presence of accumulated abnormal AAT in hepatocytes, portal inflammation, and hepatocellular degeneration were associated with clinically significant fibrosis. The accuracy of transient elastography to detect F ≥ 2 fibrosis was fair, with an AUC of 0.70 (95% CI 0.58-0.82).

CONCLUSIONS

Over one-third of asymptomatic and lung affected adults with 'PI*ZZ' AATD have significant underlying liver fibrosis. Liver biopsies demonstrated variable amounts of accumulated Z AAT. The risk of liver fibrosis increases in the presence of metabolic syndrome, accumulation of AAT in hepatocytes, and portal inflammation on baseline biopsy. The results support the hypothesis that liver disease in this genetic condition may be related to a "toxic gain of function" from accumulation of AAT in hepatocytes.

LAY SUMMARY

Individuals diagnosed with classic alpha-1 antitrypsin deficiency (ZZ) are at risk of liver injury and scarring, because of the accumulation of abnormal alpha-1 antitrypsin in the liver. A liver biopsy in ZZ individuals can demonstrate the accumulation of alpha-1 antitrypsin within the liver and identify if any associated liver scarring is present. Indviduals with large amounts of alpha-1 antitrypsin on biopsy may be at risk of liver injury and fibrosis. Additional common medical conditions of diabetes, obesity, high cholesterol, and hypertension (known as metabolic syndrome) are associated with a greater degree of liver injury. CLINICAL TRIAL NUMBER: clinicaltrials.gov NCT01810458.

Performance of the SteatoTest, ActiTest, NashTest and FibroTest in a multiethnic cohort of patients with type 2 diabetes mellitus

Fibromax is a diagnostic tool composed of the combination of 4 non-invasive biomarker panels for the diagnosis of steatosis (SteatoTest), necrosis and inflammation (ActiTest and NashTest-2) and fibrosis (FibroTest). The purpose of this study was to assess the performance of these biomarker panels in patients with type 2 diabetes mellitus (T2DM). All patients underwent routine labs, a 75 g oral glucose tolerance test, a liver proton magnetic resonance spectroscopy (¹H-MRS) to measure intrahepatic triglyceride content, and a percutaneous liver biopsy to establish the diagnosis of non-alcoholic steatohepatitis (NASH) and to grade and stage the disease in those patients with non-alcoholic fatty liver disease (NAFLD) by ¹H-MRS. For determination of the scores, plasma samples were blindly provided to establish the SteatoTest, ActiTest, NashTest-2 and FibroTest scores. A total of 220 patients with T2DM were included in this study. When the ability of the SteatoTest to identify patients with T2DM with NAFLD by ¹H-MRS was assessed, the overall performance expressed as the area under the receiver operating characteristic curve was 0.73 (95% CI 0.65 to 0.81). The performance of the ActiTest and NashTest-2 to diagnose definite NASH among patients with T2DM was 0.70 (95% CI 0.63 to 0.77) and 0.69 (95% CI 0.62 to 0.76), respectively. Regarding the FibroTest score, its performance to identify patients with moderate or advanced fibrosis was 0.67 (95% CI 0.58 to 0.76) and 0.72 (95% CI 0.61 to 0.83), respectively. Non-invasive panels for the diagnosis of steatosis, NASH and/or fibrosis, which were developed and validated in non-diabetic cohorts, underperformed when applied to a large cohort of patients with T2DM. Results from non-diabetic populations should not be extrapolated to patients with T2DM.

Response to Pioglitazone in Patients With Nonalcoholic Steatohepatitis With vs Without Type 2 Diabetes

BACKGROUND & AIMS

Pioglitazone is effective for long-term treatment of patients with nonalcoholic steatohepatitis (NASH) with prediabetes or type 2 diabetes. However, it is not clear how the presence of type 2 diabetes affects the drug's efficacy. We compared metabolic and histologic responses to pioglitazone in patients with NASH and prediabetes vs type 2 diabetes.

METHODS

We performed a prospective study of adults with biopsy-proven NASH (52 with type 2 diabetes and 49 with prediabetes), enrolled from the general population of San Antonio, Texas, from 2008 through 2014. After a run-in period of approximately 4 weeks, when all baseline measurements were made (liver magnetic resonance proton spectroscopy, euglycemic insulin clamp with glucose turnover measurements, dual-energy absorptiometry, and liver biopsy), subjects were randomly assigned to groups given pioglitazone or placebo (45 mg/d) for 18 months; all procedures performed at baseline were then repeated. The primary outcome was a reduction in nonalcoholic fatty liver disease activity score of 2 points or more (for at least 2 components) without worsening of fibrosis (and expressed as difference vs placebo). Secondary outcomes included NASH resolution, individual histologic components, intrahepatic triglyceride content (measured by ¹H magnetic resonance spectroscopy), and insulin sensitivity (measured by euglycemic insulin clamp).

RESULTS

The primary outcome was met by 48% of patients with type 2 diabetes vs 46% without diabetes. Resolution of NASH was achieved in 44% of patients with type 2 diabetes vs 26% without diabetes. A significant reduction in fibrosis, from baseline, was observed only in patients with type 2 diabetes (P = .035). Intrahepatic triglyceride content was reduced by 11% ± 2% in patients with diabetes vs a reduction of 9% ± 2% in patients without diabetes (P = .62); the plasma level of alanine aminotransferase was reduced by 50 ± 10 U/L in patients with diabetes vs a reduction of 36 ± 5 U/L in patients without diabetes (P = .22). Pioglitazone was associated with a significantly greater insulin sensitivity in adipose tissue of patients with diabetes vs without diabetes (P < .001), but nonsignificant differences in responses in hepatic (P = .49) and skeletal muscle (P = .32) insulin sensitivity.

CONCLUSIONS

In a prospective study, we found pioglitazone to be effective in patients with and without type 2 diabetes. However, pioglitazone reduced liver fibrosis and increased adipose tissue insulin sensitivity at significantly greater levels in patients with type 2 diabetes than in patients with prediabetes. Further studies are needed to determine the mechanisms by which pioglitazone reduces liver disease in patients with type 2 diabetes. ClinicalTrials.gov: NCT00994682.

Evaluating the Efficacy of a Registry linked to a Consent to Re-Contact Program and Communication Strategies for Recruiting and Enrolling Participants into Clinical Trials

INTRODUCTION

Although registries can rapidly identify clinical study participants, it is unknown which follow up methods for recruiting are most effective. Our goal is to examine the efficacy of three communication strategies for recruiting and enrolling patients who were identified via a contact registry (i.e., registry linked to a consent to re-contact program).

METHODS

Patients who met the study criteria were identified via the contact registry and targeted for recruitment. In condition 1, patients established in the university hepatology specialty clinics were contacted one time via phone call by the study coordinator and asked to participate (C1). In condition 2, non-established specialty clinic patients were mailed an IRB-approved letter with study information and instructions for calling the study coordinator to participate (C2). Condition 2A included patients who called within two weeks of receiving the letter (C2A); condition 2B included patients who did not call after receiving the letter but were subsequently contacted via phone call.

RESULTS

A registry identified 1,060 patients, of which 661were eligible and targeted for recruiting. All 37 patients were reached in C1 and 17 (45.9%) were recruited. Nineteen of the 624 patients in C2A were reached and 10 were recruited whereas 120 of the 605 patients in C2B were reached and 53 (8.7%) were recruited. Seventy patients enrolled with C2B being the most effective (total, cost) recruitment strategy (n = 50) (p < .001).

CONCLUSION

The efficacy of enrolling patients identified via a contact registry into clinical trials varies based on the communication strategies used for recruiting.

Liver Transplantation in Alpha-1 Antitrypsin Deficiency

Alpha-1 antitrypsin (AAT) deficiency is a common inherited metabolic disorder caused by a point mutation in the SERPIN1A gene. A small portion of homozygous PI*ZZ individuals develop severe liver disease that requires liver transplantation. Posttransplant survival is excellent. The largest burden of advanced liver disease lies within the adult population rather than children. Evaluation of lung function in adults before transplant is essential because of the underlying risk for chronic obstructive pulmonary disease. Post-liver transplantation lung function should also be monitored for decline. Although uncommon, cases of simultaneous lung and liver transplant for AAT deficiency have been reported.

Hepatic preservation injury: severity of hepatitis C recurrence and survival after liver transplantation

BACKGROUND

Preservation injury in the HCV liver transplant population has been reported to correlate with poorer survival outcomes compared to preservation injury in the non-HCV liver transplant population. However, determinants of progression to cirrhosis in HCV infection remain poorly defined in this population.

AIM

This study aimed to determine if the presence and severity of preservation injury impact the acceleration of HCV recurrence and survival after liver transplant.

METHODS

We retrospectively reviewed liver transplant HCV patients over a 10-year period. Biopsies from postoperative day 7 were assessed for preservation injury and 4- and 12-month biopsies were assessed for fibrosis. Patients with Ishak fibrosis >0.8 Units/year were considered rapid fibrosers.

RESULTS

Our study group consisted of 255 patients. The mean age was 49.3 years old, 180 (70.6 %) were male, and 221 (86.7 %) were Caucasian. The incidence of preservation injury on the 7-day biopsy was 69.0 %. A strong correlation between postoperative peak AST within the first week and preservation injury was found. The overall prevalence of rapid fibrosers at 4 months, 1 and 2 years was 47.4, 75.2, and 58.9 %, respectively. The prevalence of rapid fibrosers at 4 months, 1 and 2 years between patients with or without preservation injury was not statistically significant (p = 0.39, p = 0.46, and p = 0.53, respectively). No differences were seen between patients with and without PI in terms of patient and graft survival.

CONCLUSION

In this study, the presence and severity of preservation injury were not associated with development of rapid HCV recurrence or worsening in survival.

New therapeutic strategies in HCV: second-generation protease inhibitors

Telaprevir and boceprevir are the first direct-acting antiviral agents approved for use in HCV treatment and represent a significant advance in HCV therapy. However, these first-generation drugs also have significant limitations related to thrice-daily dosing, clinically challenging side-effect profiles, low barriers to resistance and a lack of pan-genotype activity. A second wave of protease inhibitors are in phase II and III trials and promise to provide a drug regimen with a better dosing schedule and improved tolerance. These second-wave protease inhibitors will probably be approved in combination with PEG-IFN and Ribavirin (RBV), as well as future all-oral regimens. The true second-generation protease inhibitors are in earlier stages of development and efficacy data are anxiously awaited as they may provide pan-genotypic antiviral activity and a high genetic barrier to resistance.

CC genotype donors for the interleukin-28B single nucleotide polymorphism are associated with better outcomes in hepatitis C after liver transplant

BACKGROUND/AIMS

Interleukin-28B (IL-28B) polymorphism is the strongest pretreatment predictor of viral clearance in the hepatitis C (HCV) population. Donor and recipient IL-28B genomic background may play an important role in post-transplant HCV recurrence. We sought to examine the role of IL-28B polymorphisms of donor and recipients in liver transplant patients with recurrent HCV and its impact on the response to interferon-based therapy.

METHODS

The cohort study consisted of 135 adult liver transplant patients who received interferon-based therapy for recurrent HCV between 1996 and 2005 at the University of Florida. IL-28B single nucleotide polymorphism (rs. 12979860) was characterized using liver tissue from all donors and recipients.

RESULTS

The CC genotype was observed in approximately 30% of donors and recipients. Sustained viral response (SVR) to HCV therapy was 100% if both recipient and donor were CC genotype, while the SVR was only 25% if neither donor nor recipient had a CC genotype. (Recipient, P = 0.025, Donor, P < 0.001). Recipients and donors with CC genotype had less fibrosis than recipients with genotypes CT and TT, but the difference was not statistically significant. IL-28B genotype did not seem to play a role in the overall survival in these patients.

CONCLUSION

In conclusion, recipient and donor CC genotype is associated with a better treatment response to interferon-based therapy after liver transplant. Our study suggests that using CC genotype donor livers for HCV patients may improve the overall clinical outcome after liver transplantation.

Liver test results do not identify liver disease in adults with α(1)-antitrypsin deficiency

BACKGROUND & AIMS

Liver disease is a significant cause of death among adults with α(1)-antitrypsin (A-AT) deficiency. Age and male sex are reported risk factors for liver disease. In the absence of adequate risk stratification, current recommendations are to intermittently test A-AT-deficient adults for liver function. We evaluated this recommendation in a large group of adults with A-AT deficiency to determine the prevalence of increased levels of alanine aminotransferase (ALT) and identify risk factors for liver disease.

METHODS

We used the Alpha-1 Foundation DNA and Tissue Bank to identify a cross section of A-AT-deficient adults (n = 647) with and without liver disease; individuals without A-AT deficiency were used as controls (n = 152). Results from ALT tests were compared between groups.

RESULTS

The prevalence of liver disease among individuals with A-AT deficiency was 7.9%; an increased level of ALT was observed in 7.8% of A-AT-deficient individuals, which did not differ significantly from controls. Mean levels of ALT fell within normal range for all groups. An increased level of ALT identified patients with liver disease with 11.9% sensitivity. The level of only γ-glutamyl transpeptidase was significantly higher in the A-AT-deficient group than in controls (43 vs 30 IU/mL; P < .003). A childhood history of liver disease and male sex were risk factors for adult liver disease in the multivariate analysis.

CONCLUSIONS

An increased level of ALT does not identify adults with A-AT deficiency who have liver disease. Male sex and liver disease during childhood might help identify those at risk.

The use of cyclosporine for recurrent hepatitis C after liver transplant: a randomized pilot study

BACKGROUND

Cyclosporine has antiviral activity in vitro against hepatitis C (HCV). We performed a pilot study to prospectively determine the antiviral effect of cyclosporine during therapy with PEGalfa-2a and ribavirin in liver transplant recipients with recurrent HCV infection.

METHODS

Patients with HCV recurrence (Ishak Fibrosis Stage > or = 2) were enrolled for 2 years at the University of Florida. Thirty-eight patients were randomized to continued tacrolimus or switched to cyclosporine. Both groups received PEGalfa-2a and ribavirin.

RESULTS

Twenty patients received tacrolimus and 18 cyclosporine, with a mean age of 53. Eighty-two percent were men, 84% Caucasian, and 90% genotype 1. In patients switched from tacrolimus to cyclosporine, HCVRNA levels decreased by a mean of 0.39 million IU/ml during the 1 month prior to initiating PEG/RBV. Sustained viral response for cyclosporine was higher than in patients on tacrolimus receiving PEG/RBV therapy.

CONCLUSIONS

This randomized controlled pilot study is the first in vivo study evaluating cyclosporine versus tacrolimus in liver transplant recipients undergoing antiviral therapy. Change from tacrolimus to cyclosporine led to a modest HCV RNA drop and appeared to enhance the antiviral response of PEG/RBV. A larger randomized study is necessary to see if cyclosporine offers any advantage over tacrolimus.