Alpha-1 Antitrypsin Augmentation and the Liver Phenotype of Adults With Alpha-1 Antitrypsin Deficiency (Genotype Pi∗ZZ)

Proteomic insights into metabolic dysfunction-associated steatotic disease: Identifying therapeutic targets and assessing on-target side effects

AIMS

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) is rising sharply, yet treatment options remain inadequate. To uncover new therapeutic targets for MASLD, we conducted a comprehensive proteome-wide Mendelian randomization (MR) and phenome-wide association study (PheWAS).

MATERIALS AND METHODS

Discovery MR utilized protein quantitative trait loci (pQTL) data on 4907 plasma protein levels from 35,559 individuals, alongside genome-wide association study (GWAS) on MASLD from the Million Veteran Program (68,725 cases / 95,482 controls). Validation comprised five pairwise combinations of these discovery datasets with three additional datasets: pQTL data for 2923 proteins from the UK Biobank, and liver biopsy-confirmed MASLD GWAS (1483 cases/17,781 controls) and MRI-liver fat GWAS (31,377 subjects) (excluding discovery pair). Candidate proteins underwent druggability assessment and on-target side effect evaluation via PheWAS.

KEY FINDINGS

We identified 26 proteins associated with MASLD after Bonferroni correction (P < 1.16 × 10-5), with 19 of them showing no significant reverse association. Interleukin-6 (IL-6), alpha-1-antitrypsin (α1-antitrypsin), 5-hydroxytryptamine receptor 7 (5-HT7R), ephrin-B1 (EFNB1), and protein MENT (CA056) were replicated. Notably, IL-6 (OR = 2.02; 95 % CI 1.54-2.64), 5-HT7R (OR = 2.73; 95 % CI 1.96-3.80), and EFNB1 (OR = 1.82; 95 % CI 1.59-2.08) were positively associated with MASLD risk, whereas α1-antitrypsin (OR = 0.84; 95 % CI 0.78-0.90) and CA056 (OR = 0.90; 95 % CI 0.86-0.94) appeared protective. Among these, IL-6, 5-HT7R, and α1-antitrypsin were druggable. PheWAS identified potential cardiovascular side effects for 5-HT7R and α1-antitrypsin.

SIGNIFICANCE

The integrative study identified several plasma proteins associated with MASLD. IL-6, α1-antitrypsin, 5-HT7R, EFNB1 and CA056 deserve further investigation as potential drug targets for MASLD.

Alpha-1 antitrypsin deficiency and primary liver cancers

Primary liver cancers (PLCs) remain a major challenge to global health and an escalating threat to human life, with a growing incidence worldwide. PLCs are composed of hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), and mixed HCC-CCA, accounting for 85 %, 10 %, and 5 % of cases, respectively. Among the numerous identified risk factors associated with liver cancers, Alpha 1-AntiTrypsin Deficiency (AATD) genetic disease emerges as an intriguing one. AATD-related liver disease may lead to chronic hepatitis, cirrhosis, and PLCs in adulthood. Although our knowledge about the natural history of AATD-liver disease has improved recently, liver cancers associated with AATD remain poorly understood and explored, while this specific population is at a 20 to 50 times higher risk of developing PLC. Thus, we review here current knowledge about AATD-associated PLCs, describing the impact of AATD genotypes on their occurrence. We also discuss emerging hypotheses regarding the AATD PiZZ genotype-related hepatic carcinogenesis process. Finally, we perform an updated analysis of the United Kingdom Biobank database that highlights and confirms AATD PiZZ genotype as an important HCC risk factor.

Alpha-1 Antitrypsin as a Regulatory Protease Inhibitor Modulating Inflammation and Shaping the Tumor Microenvironment in Cancer

Alpha-1 antitrypsin (AAT) is a key serine protease inhibitor for regulating proteases such as neutrophil elastase. AAT restrains the pulmonary matrix from enzymatic degradation, and a deficiency in AAT leads to inflammatory tissue damage in the lungs, resulting in chronic obstructive pulmonary disease. Due to the crucial biological function of AAT, the emerging research interest in this protein has shifted to its role in cancer-associated inflammation and the dynamics of the tumor microenvironment. However, the lack of comprehensive reviews in this field hinders our understanding of AAT as an essential immune modulator with great potential in cancer immunotherapy. Therefore, in this review, we have elucidated the pivotal roles of AAT in inflammation and the tumor microenvironment, including the structure and molecular properties of AAT, its molecular functions in the regulation of the inflammatory response and tumor microenvironment, and its clinical implications in cancer including its diagnosis, prognosis, and therapeutic intervention. This review seeks to bridge the gap in the understanding of AAT between inflammatory diseases and cancer, and to foster deeper investigations into its translational potential in cancer immunotherapy in the future.

Review article: New developments in biomarkers and clinical drug development in alpha-1 antitrypsin deficiency-related liver disease

BACKGROUND

Alpha-1 antitrypsin liver disease (AATLD) occurs in a subset of patients with alpha-1 antitrypsin deficiency. Risk factors for disease progression and specific pathophysiologic features are not well known and validated non-invasive assessments for disease severity are lacking. Currently, there are no approved treatments for AATLD.

AIMS

To outline existing understanding of AATLD and to identify knowledge gaps critical to improving clinical trial design and development of new treatments.

METHODS

This report was developed following a multi-stakeholder forum organised by the Alpha-1 Antitrypsin Deficiency Related Liver Disease Expert Panel in which experts presented an overview of the available literature on this topic.

RESULTS

AATLD results from a 'gain of toxic function' and primarily manifests in those with the homozygous Pi*ZZ genotype. Accumulation of misfolded 'Z' AAT protein in liver cells triggers intracellular hepatocyte injury which may ultimately lead to hepatic fibrosis. Male gender, age over 50 years, persistently elevated liver tests, concomitant hepatitis B or C virus infection, and metabolic syndrome, including obesity and type 2 diabetes mellitus, are known risk factors for adult AATLD. While the gold standard for assessing AATLD disease activity is liver histology, less invasive measures with low intra- and inter-observer variability are needed. Measurement of liver stiffness shows promise; validated thresholds for staging AATLD are in development. Such advances will help patients by enabling risk stratification and personalised surveillance, along with streamlining the development process for novel therapies.

CONCLUSIONS

This inaugural forum generated a list of recommendations to address unmet needs in the field of AATLD.