Antibody against apolipoprotein-A1, non-alcoholic fatty liver disease and cardiovascular risk: a translational study

Hormone correction of dysfunctional metabolic gene expression in stem cell-derived liver tissue

The increase in metabolic dysfunction-associated steatotic liver disease (MASLD) and its progression to metabolic dysfunction-associated steatohepatitis (MASH) is a worldwide healthcare challenge. Heterogeneity between men and women in the prevalence and mechanisms of MASLD and MASH is related to differential sex hormone signalling within the liver, and declining hormone levels during aging. In this study we used biochemically characterised pluripotent stem cell derived 3D liver spheres to model the protective effects of testosterone and estrogen signalling on metabolic liver disease 'in the dish'. We identified sex steroid-dependent changes in gene expression which were protective against metabolic dysfunction, fibrosis, and advanced cirrhosis patterns of gene expression, providing new insight into the pathogenesis of MASLD and MASH, and highlighting new druggable targets. Additionally, we highlight gene targets for which drugs already exist for future translational studies.

Linking Antibodies Against Apolipoprotein A-1 to Metabolic Dysfunction-Associated Steatohepatitis in Mice

Metabolic dysfunction-associated fatty liver disease (MASLD) is a common liver and health issue associated with heightened cardiovascular disease (CVD) risk, with Cytokeratin 18 (CK-18) as a marker of liver injury across the MASLD to cirrhosis spectrum. Autoantibodies against apolipoprotein A-1 (AAA-1s) predict increased CVD risk, promoting atherosclerosis and liver steatosis in apoE-/- mice, though their impact on liver inflammation and fibrosis remains unclear. This study examined AAA-1s' impact on low-grade inflammation, liver steatosis, and fibrosis using a MASLD mouse model exposed to AAA-1s passive immunization (PI). Ten-week-old male C57BL/6J mice under a high-fat diet underwent PI with AAA-1s or control antibodies for ten days. Compared to controls, AAA-1-immunized mice showed higher plasma CK-18 (5.3 vs. 2.1 pg/mL, p = 0.031), IL-6 (13 vs. 6.9 pg/mL, p = 0.035), IL-10 (27.3 vs. 9.8 pg/mL, p = 0.007), TNF-α (32.1 vs. 24.2 pg/mL, p = 0.032), and liver steatosis (93.4% vs. 73.8%, p = 0.007). Transcriptomic analyses revealed hepatic upregulation of pro-fibrotic mRNAs in AAA-1-recipient mice, though histological changes were absent. In conclusion, short-term AAA-1 PI exacerbated liver steatosis, inflammation, and pro-fibrotic gene expression, suggesting that AAA-1s may play a role in MASLD progression. Further research with prolonged AAA-1 exposure is warranted to clarify their potential role in liver fibrosis and associated complications.

People living with HIV display increased anti-apolipoprotein A1 auto-antibodies, inflammation, and kynurenine metabolites: a case-control study

Objective

This study aimed to study the relationship between auto-antibodies against apolipoprotein A1 (anti-apoA1 IgG), human immunodeficiency virus (HIV) infection, anti-retroviral therapy (ART), and the tryptophan pathways in HIV-related cardiovascular disease.

Design

This case-control study conducted in South Africa consisted of control volunteers (n = 50), people living with HIV (PLWH) on ART (n = 50), and untreated PLWH (n = 44). Cardiovascular risk scores were determined, vascular measures were performed, and an extensive biochemical characterisation (routine, metabolomic, and inflammatory systemic profiles) was performed.

Methods

Anti-apoA1 IgG levels were assessed by an in-house ELISA. Inflammatory biomarkers were measured with the Meso Scale Discovery® platform, and kynurenine pathway metabolites were assessed using targeted metabolomic profiling conducted by liquid chromatography-multiple reaction monitoring/mass spectrometry (LC-MRM/MS).

Results

Cardiovascular risk scores and vascular measures exhibited similarities across the three groups, while important differences were observed in systemic inflammatory and tryptophan pathways. Anti-apoA1 IgG seropositivity rates were 15%, 40%, and 70% in control volunteers, PLWH ART-treated, and PLWH ART-naïve, respectively. Circulating anti-apoA1 IgG levels were significantly negatively associated with CD4+ cell counts and positively associated with viremia and pro-inflammatory biomarkers (IFNγ, TNFα, MIPα, ICAM-1, VCAM-1). While circulating anti-apoA1 IgG levels were associated with increased levels of kynurenine in both control volunteers and PLWH, the kynurenine/tryptophan ratio was significantly increased in PLWH ART-treated.

Conclusion

HIV infection increases the humoral response against apoA1, which is associated with established HIV severity criteria and kynurenine pathway activation.

(+)-Lipoic acid reduces mitochondrial unfolded protein response and attenuates oxidative stress and aging in an in vitro model of non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a liver disorder characterized by the ac-cumulation of fat in hepatocytes without alcohol consumption. Mitochondrial dysfunction and endoplasmic reticulum (ER) stress play significant roles in NAFLD pathogenesis. The unfolded protein response in mitochondria (UPRmt) is an adaptive mechanism that aims to restore mitochondrial protein homeostasis and mitigate cellular stress. This study aimed to investigate the effects of ( +)-Lipoic acid (ALA) on UPRmt, inflammation, and oxidative stress in an in vitro model of NAFLD using HepG2 cells treated with palmitic acid and oleic acid to induce steatosis.

RESULTS

Treatment with palmitic and oleic acids increased UPRmt-related proteins HSP90 and HSP60 (heat shock protein), and decreased CLPP (caseinolytic protease P), indicating ER stress activation. ALA treatment at 1 μM and 5 μM restored UPRmt-related protein levels. PA:OA (palmitic acid:oleic acid)-induced ER stress markers IRE1α (Inositol requiring enzyme-1), CHOP (C/EBP Homologous Protein), BIP (Binding Immunoglobulin Protein), and BAX (Bcl-2-associated X protein) were significantly reduced by ALA treatment. ALA also enhanced ER-mediated protein glycosylation and reduced oxidative stress, as evidenced by decreased GPX1 (Glutathione peroxidase 1), GSTP1 (glutathione S-transferase pi 1), and GSR (glutathione-disulfide reductase) expression and increased GSH (Glutathione) levels, and improved cellular senescence as shown by the markers β-galactosidase, γH2Ax and Klotho-beta.

CONCLUSIONS

In conclusion, ALA ameliorated ER stress, oxidative stress, and inflammation in HepG2 cells treated with palmitic and oleic acids, potentially offering therapeutic benefits for NAFLD providing a possible biochemical mechanism underlying ALA beneficial effects.