30 - Immunohistochemical Study Demonstrating Expression of Collagen V and VI by Hepatic Stellate Cells

Poster Board Number: 30
There are separate poster presentation times for odd and even posters.
Odd poster #s – first hour
Even poster #s – second hour

Co-authors:

Ting-Fang Lee, PhD - Investigator, Department of Surgery, Vanderbilt University Medical Center; Youngmin Lee, MD - Investigator, Department of Surgery, Vanderbilt University Medical Center

Abstract Body :Collagen types 1, III, V and VI are the principal molecules that constitute the extracellular matrix of the liver parenchyma. Among these, collagen V is a fibrillar-forming collagen that regulates fibrilogenesis of collagen I and III fibrils, and its expression increases in the progression of hepatic fibrosis. Collagen VI is a filamentous network-forming collagen that links other collagens and extracellular proteins to form a structural scaffold in the liver parenchyma, and its expression also increases in hepatic fibrosis progression. Both collagen V and VI have wide distribution in the liver, including walls of central veins, perisinusoidal space of Disse and portal tract stroma. While hepatic stellate cells (HSC) are the main producers of collagen I and III, corresponding data for collagen V and VI production are limited. Aims and Methods: This study determined whether HSC express collagen V and VI by immunohistochemistry using antibodies against collagen V and VI, respectively, in three different protocols. Results: In normal mice, collagen V or VI immunoreactivity was detected in HSC that were also immuno-stained for reelin, a specific HSC marker. We then examined collagen V and VI immunostaining in a mouse model with depleted HSC induced by Jedi (just eGFP death-inducing) T cells. There was an obvious loss of collagen V and VI immunoreactivity in the parenchyma of liver with depletion of HSC compared to normal liver. Next, expression of collagen V and VI by HSC in vitro was evaluated. Isolated primary HSC that were positive for reelin or GFAP also showed cytoplasmic staining for collagen V or VI. Furthermore, a mouse cell line derived from primary HSC immortalized with Simian virus Large T antigen was immunoreactive to collagen V or VI. We then examined collagen V and VI in human liver. To that end, cadaveric livers with progressive stages of liver fibrosis were studied. Strong immunostaining for collagen V and VI was ubiquitous in the liver lobules—in walls of fibrotic central veins, the space of Disse showing perisinusoidal fibrosis, septa of septal fibrosis and cirrhosis, and stroma of fibrotic portal tracts. Moreover, HSC in the space of Disse revealed immunoreactivity to collagen V or VI. Conclusions: HSC in normal mouse liver express collagen V and VI. Depletion of HSC from mouse liver resulted in a loss of collagen V and VI expression in the parenchyma. In vitro, mouse HSC express collagen V and VI, corroborating the in vivo observation. Human livers demonstrate marked deposition of collagen V and VI in fibrotic foci. Looking forward, studies are warranted to assess collagen V and VI biosynthesis in HSC and their secretion into the extracellular matrix.