Cytoskeleton alterations in non-alcoholic fatty liver disease

Apocrine Gland Damage and the Release of Specific Keratins in Early Stage Indicate the Crucial Involvement of Apocrine Glands in Hidradenitis Suppurativa

The apocrine glands (AGs) are not considered to be primarily involved in hidradenitis suppurativa (HS). This study investigated the potential role of AGs in HS pathogenesis using immunohistochemistry and single-cell sequencing of nonlesional skin and early lesional skin (LS) from patients with HS (n = 12) and healthy controls (n = 8). AG cell destruction was more frequent, and AG size was significantly reduced in the nonlesional skin and LS. Barrier-related genes (eg, CLDN1 and CDH1) were downregulated in the AGs of the nonlesional skin and LS. Damaged AGs in the LS primarily recruited and activated neutrophils through the CXCL-CXCR and SAA1-FPR2 pathways. Elevated levels of specific keratins (keratin 18 and keratin 19) released from damaged AGs were observed on the skin surface of patients and were associated with disease severity. Keratin 19 was also detected in the dermis of the nonlesional skin and LS and was surrounded by neutrophils and macrophages. Moreover, serum keratin 19 levels in patients (N = 20) were significantly negatively correlated with the age at HS onset. Collectively, our findings provide previously unreported evidence that the AGs are damaged and release specific keratins in early HS lesions, indicating a crucial role of the AGs in HS pathogenesis.

Diagnostic Value of Serum Cytokeratin 18 for the Staging of Liver Inflammation and Fibrosis: A Meta-Analysis

BACKGROUND AND AIMS

Accurate assessment of liver inflammation and fibrosis is of vital importance in the clinical management of patients with liver diseases. Our aim is to conduct a meta-analysis to evaluate the diagnostic accuracy of serum cytokeratin 18 (CK18) for staging of liver inflammation and fibrosis against a liver biopsy in adults.

METHODS

We systematically searched articles from eight electronic databases. Two authors independently selected included studies, extracted data, and assessed quality. In our meta-analysis, we used the random-effects meta-analysis model. Publication bias, sensitivity analysis, heterogeneity analysis, and post-test probability were used in this meta study.

RESULTS

A total of 20 studies with 2235 patients were initially found by the search strategies. The pooled sensitivity, specificity, and area under the curve (AUC) of the summary receiver operating characteristic curve were 0.56, 0.81, and 0.810 for significant fibrosis; 0.64, 0.76, and 0.785 for advanced fibrosis; 0.53, 0.76, and 0.830 for cirrhosis; and 0.68, 0.73, and 0.786 for significant inflammation, respectively. High heterogeneity was observed in our meta-analysis because of factors such as the proportion of males, total number, and antigens of CK-18.

CONCLUSION

Serum CK18 had moderate diagnostic value (AUC > 0.7) in different stages of liver fibrosis and significant inflammation, offering a complementary approach to other non-invasive indicators such as serological biomarkers and imaging techniques. Future research should focus on elucidating the role of CK18 in the occurrence and progression of hepatitis and liver fibrosis, particularly in liver diseases with diverse etiologies.

Cytokeratin 18 fragment in liver inflammation and fibrosis: Systematic review and meta-analysis

BACKGROUND

This meta-analysis aimed to summarize the diagnostic accuracy and cut-off values of cytokeratin (CK) 18 measurements, specifically M30 and M65, as candidate biomarkers for the pathological evaluation of biopsy specimens used to stage liver inflammation and fibrosis in patients with chronic liver diseases.

METHODS

Databases were searched for studies collected up to January 11th, 2025. Pooled sensitivity, specificity, area under the receiver-operating characteristic curves, and mean cut-off values were calculated using random-effects models regardless of heterogeneity. A meta-regression analysis and subgroup analysis were performed to explore heterogeneity.

RESULTS

Sixty-three studies comprising 9137 patients were included. The summarized AUROC curve of CK18 M30 for the diagnosis of significant liver inflammation, fibrosis ≥F1, ≥F2, ≥F3, and =F4 according to the METAVIR score system were 0.82, 0.75, 0.78, 0.78 and 0.76, with mean cut-off values of 264.3, 188.0, 276.9, 322.8 and 169.4 U/L. For M65, the summarized AUROC curve for detecting significant liver inflammation, fibrosis ≥F1, ≥F2, and =F4 were 0.79, 0.70, 0.76, 0.64 and 0.72, with mean cut-off values of 541.1, 417.6, 500.1, 424.6 and 674.0 U/L. The subgroup analyses implied that ethnicity may be the primary factor related to heterogeneity in CK18 M30 when applied to detect significant inflammation. Asian patients had values 79.7 U/L higher than those of non-Asian patients (p = 0.0157).

CONCLUSIONS

CK18 M30 and M65 have clinically meaningful accuracy as alternative diagnostic tools for determining liver inflammation and fibrosis using biopsy specimens of patients with steatotic liver disease or viral hepatitis.

REGISTRATION

PROSPERO registration number: CRD42022364598.

Mechanobiology in Metabolic Dysfunction-Associated Steatotic Liver Disease and Obesity

With the ongoing obesity epidemic, the prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) is expected to rise and necessitates a greater understanding of how the disease proceeds from benign excess lipid in hepatocytes to liver fibrosis and eventually to liver cancer. MASLD is caused, at least in part, by hepatocytes' storage of free fatty acids (FAs) that dysfunctional adipocytes are no longer able to store, and therefore, MASLD is a disease that involves both the liver and adipose tissues. The disease progression is not only facilitated by biochemical signals, but also by mechanical cues such as the increase in stiffness often seen with fibrotic fatty livers. The change in stiffness and accumulation of excess lipid droplets impact the ability of a cell to mechanosense and mechanotranduce, which perpetuates the disease. A mechanosensitive protein that is largely unexplored and could serve as a potential therapeutic target is the intermediate filament vimentin. In this review, we briefly summarize the recent research on hepatocyte and adipocyte mechanobiology and provide a synopsis of studies on the varied, and sometimes contradictory, roles of vimentin. This review is intended to benefit and encourage future studies on hepatocyte and adipocyte mechanobiology in the context of MASLD and obesity.

Unveiling the hub genes associated with aflatoxin B1-induced hepatotoxicity in chicken

Aflatoxin B1 (AFB1), a ubiquitous and toxic mycotoxin in human food and animal feedstuff, can impair the function and health of some organs, especially the liver. However, the knowledge about the potential mechanisms of AFB1-induced hepatotoxicity in chickens is limited. Therefore, we analyzed the gene expression data of chicken embryo primary hepatocytes (CEPHs) treated with and without AFB1 at the dose of 0.1 μg/mL which were cultured at 37 °C in Medium 199 (Life Technologies, Shanghai, China) with 5.0% CO2 for 48 h. Totally 1,711 differentially expressed genes (DEGs) were identified, in which 1,170 and 541 genes were up- and down-regulated in AFB1-administrated CEPHs compared to the control, respectively. Biological process analysis suggested that these DEGs might take part in angiogenesis, cell adhesion, immune response, cell differentiation, inflammatory response, cell migration regulation, and blood coagulation. Signaling pathways analysis revealed that these DEGs were mainly linked to metabolic pathways, MAPK, TLR2, and actin cytoskeleton regulation pathways. Moreover, the hub genes, including GYS2, NR1H4, ALDH8A1, and ANGPTL3, might participate in AFB1-induced hepatotoxicity. Taken together, our study offers a new insight into the mechanisms of the AFB1-induced hepatotoxicity.

Mechanistic Study for Drug Induced Cholestasis Using Batch-Fabricated 3D Spheroids Developed by Agarose-Stamping Method

Cell spheroid culture can recapitulate the tissue microstructure and cellular responses in vivo. While there is a strong need to understand the modes of toxic action using the spheroid culture method, existing preparation techniques suffer from low efficiency and high cost. Herein, we developed a metal stamp containing hundreds of protrusions for batch bulk preparation of cell spheroids in each well of the culture plates. The agarose matrix imprinted by the stamp can form an array of hemispherical pits, which facilitated the fabrication of hundreds of uniformly sized rat hepatocyte spheroids in each well. Chlorpromazine (CPZ) was used as a model drug to investigate the mechanism for drug induced cholestasis (DIC) by agarose-stamping method. Hepatocyte spheroids showed a more sensitive detection of hepatotoxicity compared to 2D and Matrigel-based culture systems. Cell spheroids were also collected for staining of cholestatic protein and showed a CPZ-concentration-dependent decrease of bile acid efflux related proteins (BSEP and MRP2) and tight junction (ZO-1). In addition, the stamping system successfully delineated the DIC mechanism by CPZ that may be associated with the phosphorylation of MYPT1 and MLC2, two central proteins in the Rho-associated protein kinase pathway (ROCK), which were significantly attenuated by ROCK inhibitors. Our results demonstrated a large-scale fabrication of cell spheroids by the agarose-stamping method, with promising benefits for exploring the mechanisms for drug hepatotoxic responses.

Plasma Cytokeratin-18 Fragment Level Reflects the Metabolic Phenotype in Obesity

There is growing interest in the non-invasive identification and monitoring of the outcome of liver damage in obese patients. Plasma cytokeratin-18 (CK-18) fragment levels correlate with the magnitude of hepatocyte apoptosis and have recently been proposed to independently predict the presence of non-alcoholic steatohepatitis (NASH). The aim of the study was to analyze the associations of CK-18 with obesity and related complications: insulin resistance, impaired lipid metabolism and the secretion of hepatokines, adipokines and pro-inflammatory cytokines. The study involved 151 overweight and obese patients (BMI 25-40), without diabetes, dyslipidemia or apparent liver disease. Liver function was assessed based on alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT) and the fatty liver index (FLI). CK-18 M30 plasma levels, FGF-21, FGF-19 and cytokines were determined by ELISA. CK-18 values >150 U/l were accompanied by high ALT, GGT and FLI, insulin resistance, postprandial hypertriglyceridemia, elevated FGF-21 and MCP-1 and decreased adiponectin. ALT activity was the strongest independent factor influencing high CK-18 plasma levels, even after an adjustment for age, sex and BMI [β coefficient (95%CI): 0.40 (0.19-0.61)]. In conclusion, the applied CK-18 cut-off point at 150 U/l allows to distinguish between two metabolic phenotypes in obesity.

Impaired hepatic glucose metabolism and liver-α-cell axis in mice with liver-specific ablation of the Hepatocyte Nuclear Factor 4α (Hnf4a) gene

BACKGROUND

Hnf4a gene ablation in mouse liver causes hepatic steatosis, perturbs HDL structure and function and affects many pathways and genes related to glucose metabolism. Our aim here was to investigate the role of liver HNF4A in glucose homeostasis.

METHODS

Serum and tissue samples were obtained from Alb-Cre;Hnf4a^fl/fl (H4LivKO) mice and their littermate Hnf4a^fl/fl controls. Fasting glucose and insulin, glucose tolerance, insulin tolerance and glucagon challenge tests were performed by standard procedures. Binding of HNF4A to DNA was assessed by chromatin immunoprecipitation assays. Gene expression analysis was performed by quantitative reverse transcription PCR.

RESULTS

H4LivKO mice presented lower blood levels of fasting glucose, improved glucose tolerance, increased serum lactate levels and reduced response to glucagon challenge compared to their control littermates. Insulin signaling in the liver was reduced despite the increase in serum insulin levels. H4LivKO mice showed altered expression of genes involved in glycolysis, gluconeogenesis and glycogen metabolism in the liver. The expression of the gene encoding the glucagon receptor (Gcgr) was markedly reduced in H4LivKO liver and chromatin immunoprecipitation assays revealed specific and strong binding of HNF4A to the Gcgr promoter. H4LivKO mice presented increased amino acid concentration in the serum, α-cell hyperplasia and a dramatic increase in glucagon levels suggesting an impairment of the liver-α-cell axis. Glucose administration in the drinking water of H4LivKO mice resulted in an impressive extension of survival. The expression of several genes related to non-alcoholic fatty liver disease progression to more severe liver pathologies, including Mcp1, Gdf15, Igfbp-1 and Hmox1, was increased in H4LivKO mice as early as 6 weeks of age and this increased expression was sustained until the endpoint of the study.

CONCLUSIONS

Our results reveal a novel role of liver HNF4A in controlling blood glucose levels via regulation of glucagon signaling. In combination with the steatotic phenotype, our results suggest that H4LivKO mice could serve as a valuable model for studying glucose homeostasis in the context of non-alcoholic fatty liver disease.