Calcium pentosan polysulfate is a multifaceted exosite inhibitor of aggrecanases

Abstract

Degradation of the cartilage proteoglycan aggrecan is a key early event in the development of osteoarthritis. Adamalysin with thrombospondin motifs (ADAMTS) -4 and ADAMTS-5 are considered to be the main enzymes responsible for aggrecan breakdown, making them attractive drugs targets. Here we show that calcium pentosan polysulfate (CaPPS), a chemically sulfated xylanopyranose from beechwood, is a multifaceted exosite inhibitor of the aggrecanases and protects cartilage against aggrecan degradation. CaPPS interacts with the noncatalytic spacer domain of ADAMTS-4 and the cysteine-rich domain of ADAMTS-5, blocking activity against their natural substrate aggrecan with inhibitory concentration 50 values of 10-40 nM but only weakly inhibiting hydrolysis of a nonglycosylated recombinant protein substrate. In addition, CaPPS increased cartilage levels of tissue inhibitor of metalloproteinases-3 (TIMP-3), an endogenous inhibitor of ADAMTS-4 and -5. This was due to the ability of CaPPS to block endocytosis of TIMP-3 mediated by low-density lipoprotein receptor-related protein. CaPPS also increased the affinity of TIMP-3 for ADAMTS-4 and -5 by more than 100-fold, improving the efficacy of TIMP-3 as an aggrecanase inhibitor. Studies with TIMP-3-null mouse cartilage indicated that CaPPS inhibition of aggrecan degradation is TIMP-3 dependent. These unique properties make CaPPS a prototypic disease-modifying agent for osteoarthritis.

Differential Regulation of Extracellular Tissue Inhibitor of Metalloproteinases-3 Levels by Cell Membrane-bound and Shed Low Density Lipoprotein Receptor-related Protein 1

“…We reported previously that TIMP-3 accumulated in the conditioned medium of HTB94 cells in the presence of RAP, an antagonist of ligand binding to the LRP family of endocytic receptors (18). In line with this finding, RAP (500 nM) reduced endocytosis of [ 35 S]TIMP-3 by HTB94 cells, i.e.…”

“…We previously reported that levels of this physiologically and pathologically important inhibitor can be post-translationally regulated by endocytosis (18). TIMP-3 accumulates in the medium of HTB94 chondrosarcoma cells and porcine articular chondrocytes treated with receptorassociated protein (RAP), an antagonist of ligand binding to the LRP family of endocytic receptors (18). Using radiolabeled TIMP-3 we investigated the kinetics of TIMP-3 endocytosis and degradation by LRP-1-deficient PEA-13 mouse embryonic fibroblasts and their wild-type counterpart.…”

“…We have recently shown that TIMP-3 levels can be posttranslationally regulated by endocytosis and intracellular degradation and suggested that this is an important factor determining extracellular levels of TIMP-3 (18). In the previous studies we used endocytic blockers to demonstrate the cellular uptake of TIMP-3.…”

“…When heparin, pentosan polysulfate (PPS), or receptor-associated protein (RAP), an antagonist of ligand binding to low density lipoprotein (LDL) receptor and related receptors, was added to the cells, TIMP-3 accumulated in the medium. These studies suggested that the receptor responsible for TIMP-3 endocytosis is a member of the LDL receptor-related protein (LRP) family (18). There are 13 members in the mammalian LDL receptor family that endocytose a wide variety of ligands and deliver them to endosomes for degradation (19).…”

Mesenchymal progenitor cells combined with pentosan polysulfate mediating disc regeneration at the time of microdiscectomy: a preliminary study in an ovine model

“…23,24,43 Apart from its antiinflammatory properties, 8,9,40,41,71,72,85 PPS is a potent leukocyte elastase 4 and aggrecanase (ADAMTS-4 and ADAMTS-5) inhibitor. [77][78][79][80] Pentosan polysulfate has been shown to mediate part of its antiinflammatory effects by downregulating TNF-a activity via the suppression of NF-Kb nuclear translocation and inhibition of the MAPKs pathways. 75,76,85 Since the levels of TNF-a 68 and ADAMTS-4/ADAMTS-5 51 are elevated in degenerative discs and have been implicated in the degradation of disc PGs, the combination of PPS with MPCs in the present study offered several potential advantages over the use of MPCs alone.…”