Research Article

The Effects of Corticosteroids and Gold Therapy on the Serum Concentrations of Cartilage Oligomeric Matrix Protein in Patients with Rheumatoid Arthritis

Chikanza IC¹*and Saxne T²

¹International Arthritis and Hypermobility Centre, London W1G 7AF, UK ; and Department of Medicine, Catholic University, Harare, Zimbabwe.

²Department of Rheumatology and Department of Cell and Molecular Biology, Lund University, Lund, Sweden

Submission: August 12, 2024; Published: August 29, 2024

*Corresponding author: Chikanza IC, International Arthritis and Hypermobility Centre, London W1G 7AF, UK ; and Department of Medicine, Catholic University, Harare, Zimbabwe. , E-mail: i.c.chikanza@btinternet.com

How to cite this article: Chikanza IC* and Saxne T. The Effects of Corticosteroids and Gold Therapy on the Serum Concentrations of Cartilage Oligomeric Matrix Protein in Patients with Rheumatoid Arthritis. Ortho & Rheum Open Access J. 2024; 23(5): 556122. DOI: 10.19080/OROAJ.2024.23.556122

Abstract

Objective: Cartilage oligomeric matrix protein (COMP) has been identified and quantified in sera and synovial fluids of patients with inflammatory arthritis and osteoarthritis and the levels may reflect processes in cartilage. We have studied the effects of drug therapy on the serum levels of COMP as well as the relationship of serum COMP levels to disease activity in patients with rheumatoid arthritis (RA).

Method: COMP serum levels were measured at weeks 0, 8, 12 and 24 in patients with RA who were starting gold therapy alone (Au, n=10) and in those who received gold and intramuscular depot methyl prednisolone acetate 120 mg given at weeks 0, 4 and 8 (DMAu, n=14).

Results: The addition of intermittent intramuscular depot methyl prednisolone acetate induced a rapid onset of disease remission in the DMAu patient group as well as significantly reducing the serum levels of COMP (p=0.001) by week 12. This was followed by an increase in the levels of COMP at week 24 (p=0.05). No significant changes in the levels of COMP were seen in the Au group. There was no correlation between the levels of COMP and the radiological indices or clinical and/or laboratory indices of disease activity at any time during the study. The changes in the radiological scores were similar in the two groups of patients.

Conclusion: Intramuscular corticosteroid therapy decreases the levels of COMP in RA. COMP serum levels do not correlate with the indices of disease activity and radiological changes. Long term sequential measurements of serum concentrations of COMP may shed more light on whether COMP could be used for monitoring tissue effects of RA therapy.

Keywords: Rheumatoid Arthritis (RA); cartilage oligomeric matrix protein (COMP); corticosteroids; Microfocal radiography; Histopathological changes

Abbreviations: COMP: Cartilage oligomeric matrix protein; RA: Rheumatoid Arthritis; DM: Depot Methyl

Introduction

Pro-inflammatory cytokines (interleukin-1β and tumor necrosis factor alpha) involved in the pathogenesis of RA stimulate the synthesis of matrix metalloproteinases and other enzymes which cause proteolytic degradation of extracellular matrix macromolecules [1-4]. Fragments of cartilage matrix components are released into synovial fluid and a fraction of these reaches the circulation. These non-collagenous proteins show different distributions among cartilages [4]. One such matrix component, cartilage oligomeric matrix protein (COMP), is found in highest amounts in articular cartilage [5]. It consists of five identical subunits, each with a Mw of 83 kDa, held together in an α-helical bundle which is stabilized by disulphide bridges close to the N-terminal end [6]. COMP is the product of a unique gene which is structurally related to the thrombospondins [7]. Its true function is not fully elucidated but it has been shown to interact with collagens type I and II at very specific sites on the collagen molecule [8]. Point mutations in COMP result in severe chondrodysplasias or epiphyseal dysplasias indicating its critical role in cartilage formation and/or function [9,10]. COMP was initially considered cartilage specific but later the protein has been found in tendon, meniscus, and synovial membrane [11,12]. However, the relative abundance of the protein differs considerably, being hundred-fold higher in cartilage as compared to synovial membrane (Heinegård D, Saxne T, Månsson B, unpublished observations).

Higher levels of COMP in synovial fluid than in serum was observed in patients with RA, reactive arthritis, osteoarthritis and juvenile chronic arthritis [13]. More interestingly, patients with less advanced RA tended to have higher levels than those with advanced RA in whom most of the articular cartilage had been lost [13]. It has been suggested that measurements of serum COMP in the early course of RA could be a prognostic marker for the development of joint destruction [14], Månsson B and Saxne T, unpublished). In studies of collagen II induced arthritis in rats and mice and pristane-induced arthritis in rats, serial observations indicate, that serum COMP increases during development of arthritis to reach a maximum coinciding with developing cartilage changes, as confirmed by histopathologic observations [15,16]. Cytokine modulating treatment which reduced cartilage pathology also reduced serum COMP, whereas treatment which only reduced inflammation without influencing cartilage pathology did not influence the serum levels of COMP [17,18], Joosten LAB et al, unpublished observations). These findings convincingly show that changes in serum COMP reflect cartilage involvement despite that the protein is not entirely cartilage specific. Thus, COMP should be a suitable marker for monitoring cartilage response to therapy. Thus, serial measurements of COMP in RA patients could be a potential means to monitor the effect of therapy on articular cartilage damage and/or repair. The synovial COMP and ultrasonographic joint evaluation have been proposed as markers of disease activity and cartilage destruction in both RA and OA patients.

It has been shown that the addition of intramuscular depot methyl prednisolone acetate (DM) during the induction phase of gold therapy in RA induces a prompt onset of reduction of disease activity [19]. In this study we assed serially the effects of drug therapy on serum COMP levels in RA patients receiving gold alone or gold and DM therapy over a 24 week period. The relationship of the serum levels of COMP with the changes in clinical, laboratory indices and radiologic changes until week 24 were also analyzed.

Patients and Methods

Patients

Stored serum from patients with classical or definite RA [20] who were being commenced on gold were randomly assigned to receive in addition, intramuscular depot methyl prednisolone acetate 120 mg (DMAu, n=14) at weeks 0, 4 and 8 or continuing with gold only with placebo injections, (Au, n= 10) was used. Disease activity was measured by counting the number of tender and/or swollen joints, the duration of early morning stiffness, grip strength, visual analogue scale for pain, heamoglobin and ESR for 24 weeks. Serum was collected for the measurement of COMP at weeks 0, 8, 12 and 24.

Radiologic Assessment

Radiographs of hands and feet were taken at week 0 and repeated at week 24. The X-rays for each individual were read blind by a rheumatologist using the method of Larsen [21].

COMP Measurements

Serum COMP levels were measured by an inhibition ELISA using polyclonal antibodies raised in a rabbit against the bovine protein in Prof Saxne’s Laboratory [13]. Microtitre plates were coated with purified human COMP and standards of human COMP were included in each plate.

Statistical Analysis

The data were analysed by the Student’s t-test for significance of differences between the different time points. The relationship of COMP to clinical, laboratory and radiological parameters was assessed by Pearson’s linear correlation coefficient. A p value of <0.05 was considered significant.

Results

Clinical and Laboratory Changes

There was a significant reduction in the inflammatory disease activity in both groups as shown by a consistent improvement in clinical and laboratory indices though the response was more rapid in the DMAu group of patients compared to the Au group. There was no correlation between the clinical parameters i.e., number of tender or swollen joints (r=0.25, p=ns), early morning stiffness (r=0.27, p=ns), grip strength (r=0.24, p=ns) and the laboratory indices of disease activity i.e., ESR (r=0.37, p=ns), Hb (r=0.22, p=ns) with the levels of COMP at any time point in the study.

Serum COMP Levels

There was a significant decrease in the serum levels of COMP in the DMAu group from baseline by week 12 (p<0.001). This was followed by a significant increase in levels by week 24 (p<0.05) reaching pre-treatment levels. By contrast, there was no change in COMP levels in patients treated with gold alone.

Radiographic Changes

The median score of joint damage equally increased in the DMAu and Au groups of patients and there was no difference in the increase in joint damage score between the two groups (median increase in Larsen Index of 1.2 for Au and 0.9 for DMAu, p = ns (Table 1). Furthermore, there was no correlation between changes in the Larsen score for erosion damage and the levels of COMP.

Discussion

Gold therapy is now rarely used to treat RA having been superseded by methotrexate and the novel targeted therapies. It has a slow onset of action but the addition of intramuscular 120mg depot methyl prednisolone during the induction phase of gold therapy in patients with RA induces a rapid onset of reduction of disease activity [19]. In the present study, the combination the addition of DM to gold therapy led to a significant fall in the serum COMP levels at week 12 of therapy. Following the discontinuation of DM, the levels of COMP increased to pre-treatment levels by week 24. This indicates that corticosteroids can modulate and suppress COMP production in RA patients.

The levels of COMP did not correlate with the clinical and laboratory measures of disease activity. The radiologic changes continued to deteriorate in both groups of patients during the study period. This discordance might reflect the fact that the radiologic assessment of joint damage is not sensitive enough to detect changes in joint damage in such a short period of time in such a severely affected group of patients. We have shown that gold therapy in patients with early RA can halt the progression of erosions and initiate repair using the very sensitive radiologic technique of microfocal radiography [22]. Similar results have been obtained by Luukkainen and others using conventional radiography and Larsen radiologic scores [23,24]. However, even when using this sensitive technique, we showed that erosion area continued to increase in the first 24 weeks of gold therapy [22], supporting the notion that healing of erosions is a delayed phenomenon [25] so that perhaps X-rays in the present study should have been taken at some time point after the 6 months point.

Since COMP is released during cartilage turnover, it was hoped that the serum concentrations might reflect cartilage damage and erosion progression. However, we did not find any correlation between the serum levels and the radiographic changes. This may have at least two explanations. It is very likely that there may be differences in the sensitivity between the two techniques in the detection of joint damage with the biochemical markers being more sensitive as well as being more responsive to the effects of corticosteroids. An additional explanation is that the serum levels of COMP in RA are lower than those in paired synovial fluid and may thus only weakly reflex the processes in the joint tissues [13]. However, studies in both experimental arthritis and osteoarthritis indicate that changes in serum COMP reflect changes in cartilage matrix turnover [15-18,26]. Thus, although we cannot rule out that the variations in serum levels seen in the present study may be due to corticosteroid induced changes in the extra-articular metabolism of COMP, it is more likely that the changes seen reflect changes in cartilage turnover. More information about the synovial and lymphatic clearance as well as the hepatic elimination and renal clearance is obviously needed to verify this hypothesis [27]. Furthermore, we need to combine the results of a panel of wellcharacterized markers and to characterize the nature of released fragments to know if and when levels of a protein preferentially reflect degradation or repair.

However, the crucial experiments are those that link histopathological changes in cartilage to changes in serum COMP in experimental systems or clinical trials in which changes in serum COMP can be related to development and/or protection of joint damage by therapeutic principles with the potential to modify cartilage turnover. Work along these lines is as indicated in progress both in man and in experimental animals.

Conclusion

In conclusion, we have shown that that it is now possible to detect changes in the metabolism of COMP by serum analyses following drug therapy. The use of such sequential measurements could prove useful for monitoring the effects of therapy aimed at retarding joint damage in arthritis. Further research is needed to validate its utility and refine its clinical application.

Acknowledgement

We wish to thank Professor R Grahame, Drs L. Fernandes, B Latham and D Macfarlane, T Gibson, G S Panayi for kindly allowing us to study their patients.

Support

This work was supported in part by the Arthritis and Rheumatism Council of Great Britain. Prof T Saxne’s work was supported by the Swedish Medical Research Council, The Medical Faculty of Lund university, The Österlund, Kock and Crafoord Foundations and Reumatikerförbundet.

References

1. Firestein GS, Zvaifler NJ (1990) How important are T cells in chronic rheumatoid synovitis. Arthritis Rheum 33(6): 768-772.
2. Brennan FM, Maini RN, Feldmann M (1992) TNF alpha - A pivotal role in rheumatoid arthritis ? Brit J Rheumatol 31(5): 293-298.
3. Akira S, Hirano T, Taga T, Kishimoto I (1990) Biology of multi-functional cytokines: IL-6 and related molecules (IL-1 and TNF). FASEB J 4: 2860-2867.
4. Heinegård D, Oldberg A. Royce PM, Steinmann B, (1993) Connective tissue and its heritable disorders. Molecular, genetic, and medical aspects. (1^st edn). New York: Wiley-Liss; Glycosylated matrix proteins. p. 189-209.
5. Hedbom E, Antonsson P, Hjerpe A, Aeschlimann D, Paulsson M, et al. (1992) Cartilage matrix proteins. An acidic oligomeric protein (COMP) detected only in cartilage. J Biol Chem 267(9): 6132-6136.
6. Efimov VP, Lustig A, Engel J (1994) The thrombospondin-like chains of cartilage oligomeric matrix protein are assembled by a five-stranded alpha-helical bundle between residues 20 and 83. FEBS Lett 341(1): 54-58.
7. Oldberg Å, Antonsson P, Lindblom K, Heinegård D (1992) COMP (cartilage oligomeric matrix protein) is structurally related to thrombospondins. J Biol Chem 267(31): 223116-22350.
8. Rosenberg K, Olsson H, Mörgelin M, Heinegård D (1998) Cartilage oligomeric matrix protein shows high affinity zinc-dependent interaction with triple helical collagen. J Biol Chem 273(32): 20397-20403.
9. Ballo R, Briggs MD, Cohn DH, Knowlton RG, Beighton PH, et al. (1997) Multiple epiphyseal dysplasia, ribbing type: a novel point mutation in the COMP gene in a South African family. Am J Med Genet 68(4): 396-400.
10. Briggs MD, Mortier GR, Cole WG, King LM, Golik SS, et al. (1998) Diverse mutations in the gene for cartilage oligomeric matrix protein in the pseudoachondroplasia-multiple epiphyseal dysplasia disease spectrum. Am J Hum Genet 62(2): 311-319.
11. DiCesare CP, Carlson CS, Stollerman ES, Chen FS, Leslie M, et al. (1997) Expression of cartilage oligomeric matrix protein by human synovium. FEBS Lett 412(1): 249-252.
12. DiCesare P, Hauser N, Lehman D, Pasumarti S, Paulsson M (1994) Cartilage oligomeric matrix protein (COMP) is an abundant component of tendon. FEBS Lett 354(2): 237-240.
13. Saxne T, Heinegård D (1992) Cartilage oligomeric matrix protein: A novel marker of cartilage turnover detectable in synovial fluid and blood. Brit J Rheumatol 31(9): 583-591.
14. Forslind K, Eberhardt K, Jonsson A, Saxne T (1992) Increased serum concentration of COMP: a prognostic marker in early rheumatoid arthritis. Brit J Rheumatol 31(9): 593-598.
15. Larsson E, Mussener A, Heinegård D, Klareskog L, Saxne T (1997) Increased serum levels of cartilage oligomeric matrix protein and bone sialoprotein in rats with collagen arthritis. Br J Rheumatol 36(12): 1258-1261.
16. Vingsbo Lundgren C, Saxne T, Olsson H, Holmdahl R (1998) Increased serum levels of cartilage oligomeric matrix protein in chronic erosive arthritis in rats. Arthritis Rheum 41(3): 544-550.
17. Joosten LAB, Helsen MMA, Saxne T, van de Loo FAJ, Heinegård D, et al. (1998) Neutralization of TNF-alpha or IL-1 ameliorates disease activity in murine collagen arthritis but only anti-IL-1 treatment reduced cartilage pathology and serum cartilage oligomeric matrix protein (COMP). Arthritis Rheum 41: 9.
18. Joosten LAB, Helsen MMA, Saxne T, Heinegård D, van de Putte LBA, et al. (1998) Synergistic effects of prednisolone and IL 10 in established collagen arthritis. Arthritis Rheum 41: 9.
19. Corkill MM, Kirkham B, Chikanza IC, Gibson T, Panayi GS (1990) Intramuscular methyl prednisolone induction of chrysotherapy : A 24 week randomised double blind placebo controlled trial. Brit J Rheumatol 29(4): 274-279.
20. Ropes MW, Bennett GA, Lobbs JR, Jessar RA (1958) 1958 revision of diagnostic criteria for rheumatoid arthritis. Bull Rheum Dis 9(4): 175-176.
21. Larsen A, Dale K, Eek M (1977) Radiographic evaluation of rheumatoid arthritis and related conditions by reference films. Acta Radiol Diagn 18: 481-491.
22. Chikanza IC, Clarke GS, Buckland-Wright JC, Grahame R (1992) Quantitative microfocal radiography detects the onset of erosion repair in patients with RA treated early with myocrisin. Brit J Rheumatol 31(supl 2): 96.
23. Luukkainen R (1980) Chrysotherapy in rheumatoid arthritis: with particular emphasis on the effect of chrysotherapy on radiological changes and on the optimal time of initiation of therapy. Scand J Rheumatol 34: 1-56.
24. Sigler JW, Bluhm GB, Duncan H, Sharp JT, Ensign DC, McCrum WR (1974) Gold salts in the treatment of rheumatoid arthritis: a double blind study. Ann Intern Med 80(1): 21-26.
25. Van Leeuwen MA, Van Ryswijk MH, Van Heijide DM, Te Meerman GJ, Van Riel PL, et al. (1993) The acute phase response in early rheumatoid arthritis. Brit J Rheumatol 32: 9-13.
26. Petersson IF, Boegård T, Svensson B, Heinegård D, Saxne T (1998) Changes in cartilage and bone metabolism identified by serum markers in early osteoarthritis of the knee joint. Br J Rheumatol 37(1): 46-50.
27. Saxne T, Heinegård D, Wollheim FA (1997) Cartilage macromolecules and the development of new methods for the assessment of joint disease. Rheumatology in Europe 26(3): 108-110.