Rheumatoid Arthritis: Brömme D

Wang D, Brömme D. · Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA. · Expert Opin Drug Deliv. · Pubmed #16296806 No free full text.

Abstract: Cathepsins play important roles in the development of joint and bone diseases such as osteoporosis, rheumatoid arthritis (RA) and osteoarthritis (OA). Cathepsin inhibitors are presently in development and clinical testing for use as novel disease-modifying drugs for the improved treatment of osteoporosis. They may also be applicable for the treatment of joint diseases. However, some barriers still hamper their clinical applications in these indications. Based on pathophysiological features of RA and OA, the authors discuss six potential drug delivery strategies for the effective delivery of cathepsin inhibitors or other antiarthritic drugs to the arthritic joint tissue. Successful application of these strategies may significantly contribute to a more effective and safe treatment of RA and OA.

Yasuda Y, Kaleta J, Brömme D. · University of British Columbia, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, 2199 Wesbrook Mall, Vancouver, BC, Canada V6T 1Z3. · Adv Drug Deliv Rev. · Pubmed #15876399 No free full text.

Abstract: Human cysteine proteases of the papain family have been recognized as potential drug targets for musculoskeletal diseases. Most of the interest is focused on cathepsins S and K, which display selective expression in cells of the immune system and cells capable to efficiently degrade extracellular matrix proteins, in particular collagens. The predominant expression of cathepsin K in osteoclasts has rendered the enzyme into a major target for the development of novel anti-resorptive drugs in osteoporosis whereas cathepsin S appears to be an attractive drug target candidate for various inflammatory diseases including rheumatoid arthritis. Since rheumatoid arthritis is at the same time an inflammatory and joint destructive disorder, the combined inhibition of both cathepsins S and K should be beneficial. This review will outline the rationale and recent progress for targeting cathepsins in arthritis and osteoporosis.

Wang D, Li W, Pechar M, Kopecková P, Brömme D, Kopecek J. · Department of Pharmaceutics and Pharmaceutical Chemistry/CCCD, University of Utah, 30 S 2000 E Rm. 301, Salt Lake City, UT 84112, USA. · Int J Pharm. · Pubmed #15158970 No free full text.

Abstract: The role of the newly discovered cysteine protease, cathepsin K, in osteoporosis and rheumatoid arthritis is reviewed. The current development of cathepsin K inhibitors and their targeted delivery using synthetic polymer carriers are discussed. Future challenges and possible strategies to improve these delivery systems are addressed.

Weidauer E, Yasuda Y, Biswal BK, Cherny M, James MN, Brömme D. · Department of Human Genetics, Mount Sinai School of Medicine, New York, NY 10029, USA. · Biol Chem. · Pubmed #17338641 No free full text.

Abstract: Rheumatoid arthritis is an inflammatory and disabling joint disease affecting 0.5-1.5% of the population. Although various anti-inflammatory (NSAIDs) and disease-modifying (DMARDs) drugs are in clinical use, their precise mechanisms of action are not always defined. In this report, we discuss the effects of widely used DMARDs such as gold derivatives and chloroquine on cathepsins K and S, which have been implicated as critical mediators of inflammation and joint erosion in rheumatoid arthritis. We demonstrate that clinically potent gold derivatives inhibit cathepsins K and S in in vitro and cell-based assays. An X-ray analysis of the gold thiomalate/cathepsin K complex reveals that the inhibitor is bound to the active-site cysteine residue of the protease. Chloroquine, a lysosomotropic agent of lower clinical potency than gold derivatives, inhibits neutral pH-labile cathepsins intracellularly, but does not affect the neutral pH-stable cathepsin S. The potent inhibition of cathepsins implicated in the pathogenesis of rheumatoid arthritis by gold derivatives may explain the therapeutic efficacy of these drugs.

Wang D, Pechar M, Li W, Kopecková P, Brömme D, Kopecek J. · Department of Pharmaceutics and Pharmaceutical Chemistry/CCCD, University of Utah, 30 S 2000 E, Salt Lake City, UT 84112, USA. · Biochemistry. · Pubmed #12102627 No free full text.

Abstract: Cathepsin K is the major enzyme responsible for the degradation of the protein matrix of bone and probably for the destruction of articular cartilage in rheumatoid arthritis joints. These processes occur mainly in the resorption lacuna and within the lysosomal compartment. Here, we have designed, synthesized, and evaluated new lysosomotropic (water-soluble) polymer-cathepsin K inhibitor conjugates. In particular, we characterized the relationship between conjugate structures and their activity to inhibit cathepsins K, B, L, and papain. A potent selective cathepsin K inhibitor, 1,5-bis(N-benzyloxycarbonylleucyl)carbohydrazide, was modified to 1-(N-benzyloxycarbonylleucyl)-5-(phenylalanylleucyl)carbohydrazide (I) to facilitate polymer conjugation. It was conjugated to the polymer chain termini of two water-soluble polymers [alpha-methoxy poly(ethylene glycol), abbreviated as mPEG-I; semitelechelic poly[N-(2-hydroxypropyl)methacrylamide], abbreviated as ST-PHPMA-I]. The conjugation of inhibitor I to N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer side chains was accomplished via either a Gly-Gly spacer (PHPMA-GG-I) or with no spacer between I and the copolymer backbone (PHPMA-I). Kinetic analysis revealed that free inhibitor I possessed an apparent second-order rate constant against cathepsin K (k(obs)/[I] = 1.3 x 10(6) M(-1) s(-1)) similar to that of unmodified 1,5-bis(Cbz-Leu) carbohydrazide, while I conjugated to the chain termini of mPEG and ST-PHPMA-COOH had slightly lower values (about 5 x 10(5) M(-1) s(-1)). The k(obs)/[I] values for I attached to the side chains of HPMA copolymers (PHPMA-GG-I and PHPMA-I) were about 3 x 10(4) M(-1) s(-1). When tested against cathepsin L, inhibitor I and all its polymer conjugates produced k(obs)/[I] values 1-2 orders of magnitude less than those determined for cathepsin K, while for cathepsin B and papain, the values were 2-4 orders of magnitude lower. The ability of mPEG-I and ST-PHPMA-I to inhibit cathepsin K activity in synovial fibroblasts was also evaluated. Both polymer-bound inhibitors were internalized by endocytosis and were ultimately trafficked to the lysosomal compartment. ST-PHPMA-I was internalized faster than mPEG-I. The inhibitory activity in the synovial fibroblast assay correlated with the rate of internalization.

Hou WS, Li W, Keyszer G, Weber E, Levy R, Klein MJ, Gravallese EM, Goldring SR, Brömme D. · Mount Sinai School of Medicine, New York, New York 10029, USA. · Arthritis Rheum. · Pubmed #11920402 links to  free full text

Abstract: OBJECTIVE: To determine and compare the expression of cathepsins K and S proteins in joints with rheumatoid arthritis (RA) and osteoarthritis (OA) and to determine the effect of interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) on the expression of cathepsin K in fibroblast-like synoviocytes. METHOD: Expression and localization of cathepsins K and S were determined by immunohistochemistry in the synovium of 10 RA- and 8 OA-affected joints. Northern and Western blot analyses were performed to analyze cathepsin K and S expression in primary fibroblast-like synoviocyte cultures from RA and OA patients. The effect of IL-1 beta and TNF alpha on the expression and secretion of cathepsin K in primary cultures of synoviocytes was determined by real-time polymerase chain reaction and Western blot analysis. Staining of in situ activity was used to identify active cathepsin K enzyme in primary synovial fibroblast cultures. RESULTS: Cathepsin K and S protein expression was identified in the synovium from patients with RA and OA. Cathepsin K protein was localized in synovial fibroblasts, stromal multinucleated giant cells, and, to a lesser degree, in CD68+ macrophage-like synoviocytes. Of note is the expression of cathepsin K in synovial fibroblasts and mononuclear macrophage-like cells at sites of cartilage erosion in RA and in interdigitating cells of lymphocyte-rich areas. In contrast, cathepsin S expression was restricted to CD68+ macrophage-like synoviocytes, interdigitating cells, and endothelial cells of blood vessels. Cathepsin K protein expression in the interstitial areas and perivascular regions of RA-derived synovial specimens was 2-5 times higher than in OA samples (P < 0.001), whereas the expression of cathepsin S did not significantly differ in these diseases. Cathepsin K expression levels in normal synovium were low and restricted to fibroblast-like cells. Of note, cathepsin K also was expressed in repairing fibrocartilage in 1 OA specimen. Primary cell cultures of RA- and OA-derived synovial fibroblasts expressed comparable amounts of cathepsin K at the transcript and protein levels. Both cell cultures secreted mature cathepsin K as well as procathepsin K, and expressed active cathepsin K in cytosolic vesicles. In contrast, neither RA- nor OA-derived fibroblasts expressed detectable levels of cathepsin S. IL-1 beta and TNF alpha stimulated the transcript (7-8-fold) and protein expression (2-fold) of cathepsin K (P < 0.05) in primary synovial fibroblast cultures, without differences in expression between RA- and OA-derived synovial fibroblasts. CONCLUSION: The presence of cathepsin K polypeptide in synovial fibroblasts and macrophage-like cells in normal, OA, and RA synovia suggests a constitutive expression of this protease and a role in synovial remodeling. The comparable increase in cathepsin K expression after stimulation of RA- and OA-derived synovial fibroblasts with IL-1 beta and TNF alpha further suggests that the expression of cathepsin K is independent of cellular alterations leading to the invasive phenotype of RA-synovial fibroblasts. However, the overexpression of cathepsin K in RA synovia due to an increase in the number of cathepsin K-expressing cells identifies this enzyme as a candidate protease for the pathologic degradation of articular cartilage. Cathepsin S expression in macrophage-like synoviocytes suggests dual activity in antigen presentation and matrix degradation in the inflamed synovia.

Hou WS, Li Z, Gordon RE, Chan K, Klein MJ, Levy R, Keysser M, Keyszer G, Brömme D. · Department of Human Genetics, Mount Sinai School of Medicine, New York, New York 10029-6574, USA. · Am J Pathol. · Pubmed #11733367 links to  free full text

Abstract: Synovial fibroblasts (SFs) play a critical role in the pathogenesis of rheumatoid arthritis (RA) and are directly involved in joint destruction. Both SF-resident matrix metalloproteases and cathepsins have been implicated in cartilage degradation although their identities and individual contributions remain unclear. The aims of this study were to investigate the expression of cathepsin K in SFs, the correlation between cathepsin K expression and disease severity, and the contribution of cathepsin K to fibroblast-mediated collagen degradation. Immunostaining of joint specimens of 21 patients revealed high expression of cathepsin K in SFs in the synovial lining and the stroma of synovial villi, and to a lesser extent in CD68-positive cells of the synovial lining. Cathepsin K-positive SFs were consistently observed at sites of cartilage and bone degradation. Expression levels of cathepsin K in the sublining and vascularized areas of inflamed synovia showed a highly significant negative correlation with results derived from the Hannover Functional Capacity Questionnaire (r = 0.78, P = 0.003; and r = 0.70, P = 0.012, respectively) as a measure of the severity of RA in individual patients. For comparison, there was no correlation between Hannover Functional Capacity Questionnaire and cathepsin S whose expression is limited to CD-68-positive macrophage-like synoviocytes. The expression of cathepsin K was also demonstrated in primary cell cultures of RA-SFs. Co-cultures of SFs on cartilage disks revealed the ability of fibroblast-like cells to phagocytose collagen fibrils whose intralysosomal hydrolysis was prevented in the presence of a potent cathepsin K inhibitor but not by an inhibitor effective against cathepsins L, B, and S. The selective and critical role of cathepsin K in articular cartilage and subchondral bone erosion was further corroborated by the finding that cathepsin K has a potent aggrecan-degrading activity and that cathepsin K-generated aggrecan cleavage products specifically potentiate the collagenolytic activity of cathepsin K toward type I and II collagens. This study demonstrates for the first time a critical role of cathepsin K in cartilage degradation by SFs in RA that is comparable to its well-known activity in osteoclasts.

Li Z, Hou WS, Brömme D. · Mount Sinai School of Medicine, Department of Human Genetics, Box 1498, Fifth Avenue at 100 Street, New York, New York 10029, USA. · Biochemistry. · Pubmed #10642177 No free full text.

Abstract: Cathepsin K is the predominant cysteine protease in osteoclast-mediated bone remodeling, and the protease is thought to be involved in the pathogenesis of diseases with excessive bone and cartilage resorption. Osteoclastic matrix degradation occurs in the extracellular resorption lacuna and upon phagocytosis within the cell's lysosomal-endosomal compartment. Since glycosaminoglycans (GAGs) are abundant in extracellular matrixes of cartilage and growing bone, we have analyzed the effect of GAGs on the activity of bone and cartilage-resident cathepsins K and L and MMP-1. GAGs, in particular chondroitin sulfates, specifically and selectively increased the stability of cathepsin K but had no effect on cathepsin L and MMP-1. GAGs strongly enhanced the stability and, to a lesser extent, the catalytic activity of cathepsin K. To combine the activity and stability parameters, we defined a novel kinetic term, named cumulative activity (CA), which reflects the total substrate turnover during the life span of the enzyme. In the presence of chondroitin-4-sulfate (C-4S), the CA value increased 200-fold for cathepsin K but only 25-fold with chondroitin-6-sulfate (C-6S). C-4S dramatically increased the hydrolysis of soluble as well insoluble type I and II collagens, whereas the effects of C-6S and hyaluronic acid were less pronounced. C-4S acts in a concentration-dependent manner but reaches saturation at approximately 0.1%, a concentration similar to that found in the synovial fluid of arthritis patients. C-4S increased the cathepsin K-mediated release of hydroxyproline from insoluble type I collagen 10-fold but had only a less than 2-fold enhancing effect on the hydrolysis of intact cartilage. The relatively small increase in the hydrolysis of cartilage by C-4S was attributed to the endogenous chondroitin sulfate content present in the cartilage. Although C-4S increased the pH stability at neutral pH, a significant increase in the collagenolytic activity of cathepsin K at this pH was not observed, thus suggesting that the unique collagenolytic activity of cathepsin K at acidic pH is mechanistically determined and not by the enzyme's instability at neutral pH. The selective and significant stabilization and activation of cathepsin K activity by C-4S may provide a rationale for a novel mechanism to regulate the enzyme's activity during bone growth and aging, two processes known for significant changes in the GAG content.