Stage-dependent expression of fibrogenic markers in alcohol-related liver disease.

Alcohol-related liver disease (ALD) is the primary cause of liver-related mortality and morbidity. Liver fibrosis remains the best validated surrogate marker for patient prognosis and is usually assessed in liver biopsies using histochemical stains detecting collagen as the major extracellular matrix (ECM) component in ALD. Distinction of collagen subtypes is of clinical interest, as they, including their cleavage products, have different functions. Changes in production, distribution, and composition of specific collagen subtypes and other extracellular matrix (ECM) components as well as markers for their main cellular source (activated hepatic stellate cells (aHSCs) and myofibroblasts (MFBs)) have not been fully elucidated in ALD. Our aims were to investigate the stage-dependent expression of collagen subtypes and markers for aHSCs and MFBs in ALD. We included liver biopsies from 49 ALD patients with fibrosis stages F0-F4. Biopsies were classified according to the semi-quantitative non-alcoholic fatty liver disease (NAFLD) activity score (NAS-CRN). Slides were stained with H&E, Sirius Red, and immunohistochemically with antibodies against collagen types I, III, IV and VI, and aHSC/MFB markers α-SMA, osteonectin, and CD271. Expression was examined using automated digital imaging analysis (DIA), by calculating the positive area relative to the total liver biopsy area (proportionate area). Likewise, collagen-proportionate area (CPA) was assessed using DIA of Sirius Red stained slides. CPA correlated highly with fibrosis stage (rs = 0.88, P = 5.9E-17) and moderately with activity score (rs = 0.58, P = 0.00001). Collagen type I proportionate area increased from 0.3% (± 0.1) at F1 to 10.2% (± 1.6) at F4 (P < 0.001). Collagen type III proportionate area increased from 0.6% (± 0.2) at F0 to 11.9% (± 1.7) at F4 (P < 0.001). Collagen type IV proportionate area increased from 17.0% (± 2.5) at F0 to 27.0% (± 3.9) at F4 (P = 0.079). Collagen type VI proportionate area increased from 14.8% (± 1.4) at F0 to 31.4% (± 2.4) at F4 (P < 0.001). Proportionate areas for α-SMA and CD271 increased from 10.7% (± 1.6) and 6.5% (± 1.0) at F0 to 29.5% (± 3.4) and 22.1% (± 2.2) at F4 (P < 0.001). Proportionate area for osteonectin increased from 1.4-1.8% at F0-F2 to 3.1% (± 0.5) at F3 and 3.2% (± 0.6) at F4 (P < 0.05). In conclusion, our data indicate that collagen types I, III and VI and the aHSC/MFB markers α-SMA and CD271 show a stage-dependent increase in ALD. In early ALD, collagen types IV and VI are important components of the perisinusoidal and pericellular fibrosis. Immunohistochemistry is a valuable additional tool to characterize the ECM changes in ALD. Further research is needed to explore the functional role of CD271 and the stage-dependent expression of other collagen subtypes in ALD.

Review article: the signalling and functional role of the extracellular matrix in the development of liver fibrosis.

BACKGROUND: Patients with liver fibrosis show a large heterogeneity, and for that reason effective treatments are still lacking. Emerging data suggest that there is more to fibrosis than previously understood. Opposed to earlier belief of being a passive scaffold for cells to reside in, the extracellular matrix (ECM) is now known to hold both signalling and functional properties important for the development of fibrosis. The interaction between the ECM and the collagen-producing cells determines the course of the disease but is still poorly understood. Exploring the dynamics of this interplay will aid in the development of effective treatments. AIM: To summarise and discuss the latest advances in the pathogenesis of liver fibrosis as well as key mediators of early disease progression. METHODS: Through literature search using databases including PubMed and Google Scholar, manuscripts published between 1961 and 2019 were included to assess both well-established and recent theories of fibrosis development. Both pre-clinical and clinical studies were included. RESULTS: Fibrosis alters the structure of the ECM releasing signalling fragments with the potential to escalate disease severity. In a diseased liver, hepatic stellate cells and other fibroblasts, together with hepatocytes and sinusoidal cells, produce an excessive amount of collagens. The cell-to-collagen interactions are unique in the different liver aetiologies, generating ECM profiles with considerable patient-monitoring potential. CONCLUSIONS: The local milieu in the injured area affects the course of fibrosis development in a site-specific manner. Future research should focus on the dissimilarities in the ECM profile between different aetiologies of liver fibrosis.

Serological Assessment of Activated Fibroblasts by alpha-Smooth Muscle Actin (α-SMA): A Noninvasive Biomarker of Activated Fibroblasts in Lung Disorders.

OBJECTIVES: Remodeling of the extracellular matrix (ECM) is a key event in different lung disorders, such as fibrosis and cancer. The most common cell type in the connective tissue is fibroblasts, which transdifferentiate into myofibroblasts upon activation. All myofibroblasts express α-SMA, which has been found to be upregulated in lung fibrosis and cancer. We evaluated the potential of α-SMA as a noninvasive biomarker of activated fibroblasts in lung fibrosis and cancer. METHODS: A monoclonal antibody was raised against the N-terminal of α-SMA, and a novel competitive enzyme-linked immunosorbent assay (ELISA) measuring α-SMA was developed and technically characterized. Levels of α-SMA were measured in the fibroblast model, "scar-in-a-jar", and in serum from patients with idiopathic pulmonary fibrosis (IPF), chronic obstructive lung disorder (COPD) and non-small cell lung cancer (NSCLC) belonging to two different cohorts. RESULTS: The novel α-SMA assay was developed and validated as technically robust. Based on the scar-in-a-jar results, α-SMA was only present in the fibroblasts activated by TGF-ß. In cohort 1, levels of α-SMA were significantly higher in IPF, COPD and NSCLC patients compared to healthy controls (P = 0.04, P = 0.001 and P <0.0001, respectively). The area under the receiver operating characteristics (AUROC) for separation of healthy controls from IPF patients was 0.865, healthy controls from COPD patients was 0.892 and healthy controls from NSCLC patients was 0.983. In cohort 2, levels of α-SMA were also significantly higher in NSCLC patients compared to healthy controls (P = 0) and the AUROC for separating NSCLC and healthy controls was 0.715. CONCLUSIONS: In this study we developed and validated a robust competitive ELISA assay targeting the N-terminal of α-SMA. The level of α-SMA was upregulated when adding TGF-ß, indicating that α-SMA is increased in activated fibroblasts. The level of α-SMA in circulation was significantly higher in patients with IPF, COPD and NSCLC compared to healthy controls. This assay could potentially be used as a novel noninvasive serological biomarker for lung disorders by providing a surrogate measure of activated fibroblasts.