Hyaluronan histochemistry—a potential new tool to assess the progress of liver disease from simple steatosis to hepatocellular carcinoma

Abstract

Non-alcoholic fatty liver disease is among the most common liver diseases worldwide and one cause of cirrhosis that can result in the development of hepatocellular carcinoma (HCC). Hyaluronan (HA) is a high-molecular-mass glycosaminoglycan with diverse functions in tissue injury and repair, for instance, in inflammation and fibrogenesis. The aim of the present study was to investigate the relationships between the HA synthesizing and degrading enzymes in a spectrum of liver pathologies. This was realized by histological staining of liver sections from controls and patients with simple steatosis, steatohepatitis, cirrhosis, and HCC (n = 90). HA-positive staining intensified in connective tissue in all liver pathologies, and staining of CD44, the major HA receptor, similarly increased in steatohepatitis and cirrhosis. HA synthase 1 (HAS1)-positive staining was reduced in steatosis, steatohepatitis, and HCC. Staining of HAS3, which produces HA of a lower molecular mass, promotes inflammation, and is pathogenic in animal models, increased in all diagnoses. The responses in staining intensity of HAS2 and hyaluronidases 1-2 were specific for different cell types. These findings suggest that HAS1-2 are responsible for HA synthesis in healthy livers, while HAS3 increases in importance in liver diseases. It is noteworthy that the pathological changes in HA metabolism are already visible in simple steatosis and, thus, precede the histological changes of inflammation and fibrosis. It could be possible to intervene in disease progression at an early stage by influencing HA metabolism. The results could have potential clinical applications with HAS3 immunostaining supplementing the existing HCC diagnostics.

Immunomodulatory Role of the Extracellular Matrix Within the Liver Disease Microenvironment

“…This produces LMW-HA that gathers at sites of active tissue catabolism and promotes inflammation. In a study by Mustonen and colleagues, the relationship between HA synthesis and degrading enzymes was demonstrated in histological stainings of liver sections from controls and patients with steatosis, steatohepatitis, cirrhosis and HCC (197), highlighting the importance of HA turnover in healthy liver and in CLD.…”

“…-Facilitates viral particle binding in both HBV and HCV (189,190) LMW-HA TLR2, TLR4, CD44 (119,120,122,(191)(192)(193) Direct Ligand: Immune cell interactions -Generated during inflammation and tissue injury by endogenous and bacterial hyaluronidases and by mechanical forces and oxidative stress (194,195) -Activates pro-inflammatory response in macrophages (119,121,122), dendritic cells via TLR4 and endothelial cells (191) -Stimulates macrophages to produce IL-8, IL-12, MIP-1a, MIP-1b, and MCP-1 (119,121,122) -Stimulates DCs and endothelial cells to produce IL-1b, TNF-a, and IL-12 (191) ECM-DAMP -LMW-HA is considered an ECM-DAMP known to activate the inflammasome and subsequently caspase-1 (126). The activation of the -Hyaluronic acid is upregulated in liver connective tissue of patients with steatosis, steatohepatitis, cirrhosis, and HCC (197) (Continued) and HSCs, HBV core protein was able to induce expression of TSP-1 by hepatic cells and induce activation of TGF-b1 (294).…”

Interplay between Cellular and Non-Cellular Components of the Tumour Microenvironment in Hepatocellular Carcinoma

“…By binding to integrins, it increases focal adhesions, initiates PI3K signalling and promotes the growth of tumour cells [39]. There is elevated deposition of other stromal components such as hyaluronic acid (HA) and its receptor CD44 that together increase growth factor signalling [40]. Other components such as heparan sulphate proteoglycans are also excessively produced [36] and due to their involvement in cancer signalling, proteoglycans have been proposed as potential biomarkers and therapeutic candidates in HCC [41].…”

The Role of the Tumor Microenvironment in the Development and Progression of Hepatocellular Carcinoma

“…Activities of these enzymes are shown to greatly influence tumor growth and metastasis (15). HA is overexpressed in both cirrhotic and liver tumor tissues, promoting tumor progression (16,17). Several pieces of evidence indicate that HA inhibition by 4-methylumbelliferone (4-MU), a specific HA synthesis inhibitor, delays HCC growth (18,19).…”