HSD17B13 as a promising therapeutic target against chronic liver disease

Precision medicine and nucleotide-based therapeutics to treat steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a complex multifactorial disease and becoming the leading cause of liver-related morbidity and mortality. MASLD spans from isolated steatosis to metabolic dysfunction-associated steatohepatitis (MASH), that may progress to cirrhosis and hepatocellular carcinoma (HCC). Genetic, metabolic, and environmental factors strongly contribute to the heterogeneity of MASLD. Lifestyle intervention and weight loss represent a viable treatment for MASLD. Moreover, Resmetirom, a thyroid hormone beta receptor agonist, has recently been approved for MASLD treatment. However, most individuals treated did not respond to this therapeutic, suggesting the need for a more tailored approach to treat MASLD. Oligonucleotide-based therapies, namely small-interfering RNA (siRNA) and antisense oligonucleotide (ASO), have been recently developed to tackle MASLD by reducing the expression of genes influencing MASH progression, such as PNPLA3 and HSD17B13. Here, we review the latest progress made in the synthesis and development of oligonucleotide-based agents targeting genetic determinants of MASH.

The rs72613567:TA polymorphism in HSD17B13 is associated with survival benefit after development of hepatocellular carcinoma

BACKGROUND

The influence of genetic factors on survival following a diagnosis of hepatocellular carcinoma (HCC) remains unclear.

AIM

To assess whether genetic polymorphisms influencing the susceptibility to develop HCC are also associated with HCC prognosis.

METHODS

We included United Kingdom Biobank (UKB) participants diagnosed with HCC after study enrolment. The primary outcome was all-cause mortality. Patients were followed from the date of HCC diagnosis to death or the registry completion date. Five HCC susceptibility loci were investigated: rs738409 (PNPLA3), rs58542926 (TM6SF2); rs72613567 (HSD17B13); rs2242652 (TERT) and rs708113 (WNT3A). The associations between these genetic variants and HCC mortality risk were assessed using Cox regression, adjusted for age, sex, ethnicity, aetiology, severity of the underlying liver disease and receipt of curative HCC treatment.

RESULTS

The final sample included 439 patients; 74% had either non-alcoholic fatty liver disease or alcohol-related liver disease. There were 321 deaths during a mean follow-up of 1.9 years per participant. Kaplan-Meier survival estimates at 1, 3 and 5 years were 53.2%, 31.2% and 22.6% respectively. In multivariate analysis, rs72613567:TA (HSD17B13) was the only genetic susceptibility variant significantly associated with all-cause mortality risk (aHR: 0.74; 95% CI: 0.61-0.90; p = 0.003). Other associated factors were Baveno stage 3-4 (aHR: 1.65; 95% CI: 1.05-2.59; p = 0.03) and HCC treatment with curative intent (aHR: 0.25; 95% CI: 0.17-0.37; p < 0.001).

CONCLUSIONS

The rs72613567:TA polymorphism in HSD17B13 is not only associated with a reduction in the risk of developing HCC but with a survival benefit in HCC once established. Therapeutic inhibition of HSD17B13 may augment survival in individuals with HCC.

Liver phenotypes in PCOS: Analysis of exogenous and inherited risk factors for liver injury in two European cohorts

BACKGROUND & AIMS

Fatty liver disease (FLD) is common in women with polycystic ovary syndrome (PCOS). Here, we use non-invasive tests to quantify liver injury in women with PCOS and analyse whether FLD-associated genetic variants contribute to liver phenotypes in PCOS.

METHODS

Prospectively, we recruited women with PCOS and controls at two university centres in Germany and Poland. Alcohol abuse was regarded as an exclusion criterion. Genotyping of variants associated with FLD was performed using TaqMan assays. Liver stiffness measurements (LSM), controlled attenuation parameters (CAP) and non-invasive HSI, FLI, FIB-4 scores were determined to assess hepatic steatosis and fibrosis.

RESULTS

A total of 42 German (age range 18-53 years) and 143 Polish (age range 18-40 years) women with PCOS, as well as 245 German and 289 Polish controls were recruited. In contrast to Polish patients, Germans were older, presented with more severe metabolic profiles and had significantly higher LSM (median 5.9 kPa vs. 3.8 kPa). In the German cohort, carriers of the PNPLA3 p.I148M risk variant had an increased LSM (p = .01). In the Polish cohort, the minor MTARC1 allele was linked with significantly lower serum aminotransferases activities, whereas the HSD17B13 polymorphism was associated with lower concentrations of 17-OH progesterone, total testosterone, and androstenedione (all p < .05).

CONCLUSIONS

FLD is common in women with PCOS. Its extent is modulated by both genetic and metabolic risk factors. Genotyping of variants associated with FLD might help to stratify the risk of liver disease progression in women suffering from PCOS.

Letrozole ameliorates liver fibrosis through the inhibition of the CTGF pathway and 17β-hydroxysteroid dehydrogenase 13 expression

BACKGROUND

To establish a treatment option for liver fibrosis, the possibility of the drug repurposing theory was investigated, with a focus on the off-target effects of active pharmaceutical ingredients.

METHODS

First, several active pharmaceutical ingredients were screened for their effects on the gene expression in the hepatocytes using chimeric mice with humanized hepatocytes. As per the gene expression-based screening assay for 36 medications, we assessed the mechanism of the antifibrotic effect of letrozole, a third-generation aromatase inhibitor, in mouse models of liver fibrosis induced by carbon tetrachloride (CCl4) and a methionine choline-deficient (MCD) diet. We assessed liver histology, serum biochemical markers, and fibrosis-related gene and protein expressions in the hepatocytes.

RESULTS

A gene expression-based screening assay revealed that letrozole had a modifying effect on fibrosis-related gene expression in the hepatocytes, including YAP, CTGF, TGF-β, and CYP26A1. Letrozole was administered to mouse models of CCl4- and MCD-induced liver fibrosis and it ameliorated the liver fibrosis. The mechanisms involved the inhibition of the Yap-Ctgf profibrotic pathway following a decrease in retinoic acid levels in the hepatocytes caused by suppression of the hepatic retinol dehydrogenase, Hsd17b13 and activation of the retinoic acid hydrogenase, Cyp26a1.

CONCLUSIONS

Letrozole slowed the progression of liver fibrosis by inhibiting the Yap-Ctgf pathway. The mechanisms involved the modification of the Hsd17b13 and Cyp26a1 expressions led to the suppression of retinoic acid in the hepatocytes, which contributed to the activation of Yap-Ctgf pathway. Because of its off-target effect, letrozole could be repurposed for the treatment of liver fibrosis. The third-generation aromatase inhibitor letrozole ameliorated liver fibrosis by suppressing the Yap-Ctgf pathway by partially modifying the Hsd17b13 and Cyp26a1 expressions, which reduced the retinoic acid level in the hepatocytes. The gene expression analysis using chimeric mice with humanized liver revealed that the mechanisms are letrozole specific and, therefore, may be repurposed for the treatment of liver fibrosis.

Advances in pediatric non-alcoholic fatty liver disease: From genetics to lipidomics

As a result of the obesity epidemic, non-alcoholic fatty liver disease (NAFLD) represents a global medical concern in childhood with a closely related increased cardiometabolic risk. Knowledge on NAFLD pathophysiology has been largely expanded over the last decades. Besides the well-known key NAFLD genes (including the I148M variant of the PNPLA3 gene, the E167K allele of the TM6SF2, the GCKR gene, the MBOAT7-TMC4 rs641738 variant, and the rs72613567:TA variant in the HSD17B13 gene), an intriguing pathogenic role has also been demonstrated for the gut microbiota. More interestingly, evidence has added new factors involved in the "multiple hits" theory. In particular, omics determinants have been highlighted as potential innovative markers for NAFLD diagnosis and treatment. In fact, different branches of omics including metabolomics, lipidomics (in particular sphingolipids and ceramides), transcriptomics (including micro RNAs), epigenomics (such as DNA methylation), proteomics, and glycomics represent the most attractive pathogenic elements in NAFLD development, by providing insightful perspectives in this field. In this perspective, we aimed to provide a comprehensive overview of NAFLD pathophysiology in children, from the oldest pathogenic elements (including genetics) to the newest intriguing perspectives (such as omics branches).

Human and molecular genetics shed lights on fatty liver disease and diabetes conundrum

The causal role of abdominal overweight/obesity, insulin resistance and type 2 diabetes (T2D) on the risk of fatty liver disease (FLD) has robustly been proven. A consensus of experts has recently proposed the novel definition of 'metabolic dysfunction-associated fatty liver disease, MAFLD' instead of 'nonalcoholic fatty liver disease, NAFLD', emphasizing the central role of dysmetabolism in the disease pathogenesis. Conversely, a direct and independent contribution of FLD per se on risk of developing T2D is still a controversial topic. When dealing with FLD as a potential risk factor for T2D, it is straightforward to think of hepatic insulin resistance as the most relevant underlying mechanism. Emerging evidence supports genetic determinants of FLD (eg PNPLA3, TM6SF2, MBOAT7, GCKR, HSD17B13) as determinants of insulin resistance and T2D. However, recent studies highlighted that the key molecular mechanism of dysmetabolism is not fat accumulation per se but the degree of hepatic fibrosis (excess liver fat content-lipotoxicity), leading to reduced insulin clearance, insulin resistance and T2D. A consequence of these findings is that drugs that will ameliorate liver fat accumulation and fibrosis in principle may also exert a beneficial effect on insulin resistance and risk of T2D in individuals with FLD. Finally, initial findings show that these genetic factors might be directly implicated in modulating pancreatic beta-cell function, although future studies are needed to fully understand this relationship.

Pharmacokinetics and pharmacogenetics of sorafenib in patients with hepatocellular carcinoma: Implications for combination trials

BACKGROUND & AIMS

Sorafenib and lenvatinib are the first-line treatments approved in hepatocellular carcinoma (HCC), but information is lacking about the relationships between their pharmacokinetics, patients pharmacogenetic profiles, adverse events (AE) and overall survival. We aimed to elucidate these relationships of tyrosine Kinase Inhibitors, such as sorafenib, in order to improve the design of trials testing it in combination with checkpoint inhibitors.

METHODS

We assessed the pharmacokinetics of sorafenib and its N-oxide metabolite at day-0, day-7, day-30, day-60, day-90, day-120, day-150 and day-180 and nine single-nucleotide polymorphisms (SNP) in five genes related to sorafenib metabolism/transport to identify the best point for starting the combination between tyrosine kinases and checkpoint inhibitors.

RESULTS

We prospectively included 49 patients (96% cirrhotic, 37% hepatitis-C, 82% Child-Pugh-A and 59% BCLC-C). Pharmacokinetic values peaked at day-7 and progressively declined until day-60. In the 16 patients without further dose modifications after day-60, pharmacokinetic values remained stable through day-180 (sorafenib P = .90; N-oxide P = .93). Pharmacokinetic values were higher in patients with early dermatological adverse events and lower in patients with early diarrhoea. Sorafenib and N-oxide pharmacokinetic values varied linearly with different alleles of MRP2*3972.

CONCLUSIONS

Sorafenib's pharmacokinetics is heterogeneous across HCC patients. This heterogeneity affects adverse events development and must be taken into account in setting the dose and timing of its combination with checkpoint inhibitors.

Genetic Susceptibility to Chronic Liver Disease in Individuals from Pakistan

Chronic liver disease, with viral or non-viral etiology, is endemic in many countries and is a growing burden in Asia. Among the Asian countries, Pakistan has the highest prevalence of chronic liver disease. Despite this, the genetic susceptibility to chronic liver disease in this country has not been investigated. We performed a comprehensive analysis of the most robustly associated common genetic variants influencing chronic liver disease in a cohort of individuals from Pakistan. A total of 587 subjects with chronic liver disease and 68 healthy control individuals were genotyped for the HSD17B13 rs7261356, MBOAT7 rs641738, GCKR rs1260326, PNPLA3 rs738409, TM6SF2 rs58542926 and PPP1R3B rs4841132 variants. The variants distribution between case and control group and their association with chronic liver disease were tested by chi-square and binary logistic analysis, respectively. We report for the first time that HSD17B13 variant results in a 50% reduced risk for chronic liver disease; while MBOAT7; GCKR and PNPLA3 variants increase this risk by more than 35% in Pakistani individuals. Our genetic analysis extends the protective role of the HSD17B13 variant against chronic liver disease and disease risk conferred by the MBOAT7; GCKR and PNPLA3 variants in the Pakistani population.