Addition of High Molecular Weight Hyaluronic Acid to Fibroblast-Like Stromal Cells Modulates Endogenous Hyaluronic Acid Metabolism and Enhances Proteolytic Processing and Secretion of Versican.

Jiapeng Xue,Jun Li,Quan Shen,Faizan Niazi,Tannin A Schmidt,Anna Plaas,Deva Chan,Adam P Tanguay,Jinnan Chen

doi:10.3390/cells9071681

Abstract

We have examined the effect of exogenous linear chain high molecular weight hyaluronic acid (HMW HA) on endogenously synthesized hyaluronic acid (HA) and associated binding proteins in primary cultures of fibroblast-like stromal cells that were obtained by collagenase digestion of the murine peripatellar fat pad. The cultures were expanded in DMEM that was supplemented with fetal bovine serum and basic fibroblast growth factor (bFGF) then exposed to macrophage-colony-stimulating factor (MCSF) to induce macrophage properties, before activation of inflammatory pathways using E. coli lipopolysaccharide (LPS). Under all culture conditions, a significant amount of endogenously synthesized HA localized in LAMP1-positive lysosomal vesicles. However, this intracellular pool was depleted after the addition of exogenous HMW HA and was accompanied by enhanced proteolytic processing and secretion of de novo synthesized versican, much of which was associated with endosomal compartments. No changes were detected in synthesis, secretion, or proteolytic processing of aggrecan or lubricin (PRG4). The addition of HMW HA also modulated a range of LPS-affected genes in the TLR signaling and phagocytosis pathways, as well as endogenous HA metabolism genes, such as Has1, Hyal1, Hyal2, and Tmem2. However, there was no evidence for association of endogenous or exogenous HMW HA with cell surface CD44, TLR2 or TLR4 protein, suggesting that its physiochemical effects on pericelluar pH and/or ionic strength might be the primary modulators of signal transduction and vesicular trafficking by this cell type. We discuss the implications of these findings in terms of a potential in vivo effect of therapeutically applied HMW HA on the modification of osteoarthritis-related joint pathologies, such as pro-inflammatory and degradative responses of multipotent mesenchymal cells residing in the synovial membrane, the underlying adipose tissue, and the articular cartilage surface.

Highlights

Many chronic musculoskeletal diseases are driven by innate inflammatory responses following acute or chronic soft tissue injuries and they can lead to tissue destruction and pain with long term disabilities
We assayed the expression of genes involved in hyaluronic acid (HA) synthesis and extracellular organization previously reported to be expressed by fibroblastic cell types (Has1, Has2, Tnfaip6, Petx3, and CD44) and HA degradation (Hyal1, Hyal2, Tmem2, and Cemip) to determine the capacity of the cells for endogenous HA metabolism
In the in vitro inflammation model system, exogenous high molecular weight hyaluronic acid (HMW HA) was not associated with cell surface CD44, TLR2, or TLR4 and, the effects on gene modulation are unlikely to be mediated through these receptors

Summary

Introduction

Many chronic musculoskeletal diseases are driven by innate inflammatory responses following acute or chronic soft tissue injuries and they can lead to tissue destruction and pain with long term disabilities. The majority of research on these diseases, such as osteoarthritis (OA) [1,2,3] and the tendinopathies [4,5], have focused on defining the involvement of specific tissue and cell types as well as inflammatory mediators and down-stream signaling pathways These considerations have largely guided translational research approaches in the attempt to discover new therapeutics to slow disease progression and to alleviate pain and disability. Research on the pathogenesis of chronic diseases in organs such as the liver, gut, kidney, respiratory, and cardiovascular tissues, has evaluated the prominent role of the polysaccharide-rich pericellular matrix (glycocalyx) [6,7,8] This has been studied in a more limited way in the musculoskeletal diseases. While a number of studies report on the effects of (HMW HA) injections in diminishing tissue inflammation and joint pain in symptomatic OA patients, the lack of appropriate global guidelines for clinical trial designs has resulted in heterogeneity of the research, impeding the more widespread use of this therapy in slowing the progression of OA [16,17]

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