C71-12 Mrc2-Deficient Cell-Derived Matrix Modulates Lung Fibroblast Profibrotic-like Characteristics

Abstract Rationale Mannose Type C receptor (MRC2) is a fibroblast-enriched endocytic receptor in the lung that is critical for collagen turnover. Dysregulation of MRC2-mediated collagen uptake has been implicated in the development of lung fibrosis. In previous studies, we demonstrated that MRC2-null mice exhibit increased lung stiffness at baseline, despite no detectable changes in total collagen content as measured by hydroxyproline. Furthermore, lung fibroblasts from MRC2-null mice show enhanced proliferation. Building on these findings, we investigated whether the extracellular matrix (ECM) associated with MRC2 deficiency influences fibroblast phenotype by assessing the expression of Yap/Taz—transcriptional effectors of the Hippo pathway—and TGF-β1, all of which are well-established key regulators of matrix remodeling and fibrosis. Methods Primary mouse lung fibroblasts were harvested from age- and sex-matched wild-type (WT) and MRC2-null mice. Fibroblasts were cultured in 24-well plates for 14 days with ascorbic acid to allow maximal matrix accumulation. The resulting cell-derived matrices were subsequently decellularized, then reseeded with either WT or MRC2-null cells. The cells were then collected 24 hours post-reseeding and RNA was extracted for quantitative real-time PCR (qPCR) analysis. Results qPCR analysis revealed that WT fibroblasts reseeded onto ECM derived from MRC2-null cells exhibited significantly increased expression of Yap, Taz and Tgfb1 compared to those reseeded onto WT ECM. Further, MRC2-null fibroblasts show the same response to MRC2-null matrix suggesting that this fibroblast phenotype is dominated by the matrix and is likely cell-extrinsic. Conclusions MRC2-null fibroblasts produce a matrix that promotes a profibrotic-like phenotype, underscoring the importance of the ECM in shaping fibroblast activation and responses. Ongoing and future studies will assess the effect of the MRC2-null ECM on other aspects of fibroblast biology, such as morphology and proliferation, as well as investigate the key differences in MRC2-null ECM that are responsible for modulating fibroblast phenotype. This abstract is funded by: Department of Defense