LR8 gene expression in normal and fibrotic human tissues

LR8 gene was first isolated from a subpopulation of human lung fibroblasts expressing the C1q receptor. LR8 expression was found to be upregulated in human lungs with IPF and bleomycin-induced fibrotic mouse lungs. Previous studies on LR8 expression in gingival fibroblasts have shown that LR8 gene is expressed in fibroblasts cultured from only some healthy patients, whereas it was expressed in fibroblasts from all patients with phenytoin induced gingival overgrowth. The purpose of this study was to determine if fibroblasts expressing LR8 also express SMA and if these cells are selected and expanded in human fibrosis. Real time quantitative PCR was performed with normal and fibrotic liver and gingiva to quantitate expression of LR8, SMA and COL1A1 genes. Immunohistochemistry was performed in normal and fibrotic human tissues using LR8 and SMA antibodies. RT-PCR was performed to examine the presence of variants of LR8 gene in liver and gingiva. There was considerable variability in LR8 gene expression among the individual human patients in the results from PCR. LR8 expression was higher in fibrotic liver tissues as compared to normal liver tissues and there was lack of correlation between LR8 and SMA expression in tissues. Number of LR8 expressing cells increased in fibrotic tissues and number of cells coexpressing both LR8 and SMA increased in fibrosis. RT-PCR using three sets of primers from different LR8 domains showed tissue specific differences in LR8 expression between human liver and gingiva.