Spontaneous production of nitric oxide (NO), prostaglandin (PGE2) and neutral metalloproteinases (NMPs) in media of explant cultures of equine synovial membrane and articular cartilage from normal and osteoarthritic joints

Studying Edema Formation After Release of the Infraspinatus Muscle as an Experimental Model of Rotator Cuff Lesions in Sheep: A Histological Analysis

BACKGROUND

Muscle edema formation and inflammatory processes are early manifestations of acute rotator cuff lesions in sheep. Histological analysis of affected muscles revealed edema formation, inflammatory changes, and muscle tissue disruption in MRs.

HYPOTHESIS

Edema contributes to inflammatory reactions and early muscle fiber degeneration before the onset of fatty infiltration.

STUDY DESIGN

Controlled laboratory study.

METHODS

Osteotomy of the greater tuberosity, including the insertion of the infraspinatus tendon, was performed on 14 sheep. These experimental animal models were divided into 2 groups: a nontrauma group with surgical muscle release alone (7 sheep) and a trauma group with standardized application of additional trauma to the musculotendinous unit (7 sheep). Excisional biopsy specimens of the infraspinatus muscle were taken at 0, 3, and 4 weeks.

RESULTS

Edema formation was histologically demonstrated in both groups and peaked at 3 weeks. At 3 weeks, signs of muscle fiber degeneration were observed. At 4 weeks, ingrowth of loose alveolar and fibrotic tissue between fibers was detected. Fatty tissue was absent. The diameter of muscle fibers increased in both groups, albeit to a lesser degree in the trauma group, and practically normalized at 4 weeks. Immunohistology revealed an increase in macrophage types 1 and 2, as well as inflammatory mediators such as prostaglandin E2 and nuclear factor kappa-light-chain-enhancer of activated B cells.

CONCLUSION

Early muscle edema and concomitant inflammation precede muscle fiber degeneration and fibrosis. Edema formation results from tendon release alone and is only slightly intensified by additional trauma.

CLINICAL RELEVANCE

This study illustrates that early edema formation and inflammation elicit muscle fiber degeneration that precedes fatty infiltration. Should this phenomenon be applicable to human traumatic rotator cuff tears, then surgery should be performed as soon as possible, ideally within the first 21 days after injury.

Role of vasoactive intestinal peptide in osteoarthritis

Vasoactive intestinal peptide (VIP) plays important roles in many biological functions, such as, stimulation of contractility in the heart, vasodilation, promoting neuroendocrine-immune communication, lowering arterial blood pressure, and anti-inflammatory and immune-modulatory activity. Osteoarthritis (OA) is a chronic and degenerative bone disease, which is one of the most common causes of disability and most common in both sexes as people become older. Interestingly VIP can prevent chronic cartilage damage and joint remodeling. This review article provides update information on the association of VIP and OA and its treatment. Evidences suggest that VIP is down-regulated in synovial fluid of OA, and VIP down-regulation leads to increase in the production of pro-inflammatory cytokines that might contribute to the pathogenesis of OA; however contradictory reports also exist suggesting that accumulation of VIP in joints can also contribute OA. A number of studies indicated that up-regulation of VIP can counteract the action of pro-inflammatory stimuli and alleviate the pain in OA. More clinical investigations are necessary to determine the biology of VIP and its therapeutic potential in OA that might represent the future standards of care for OA.

Biomarkers of antioxidant status, inflammation, and cartilage metabolism are affected by acute intense exercise but not superoxide dismutase supplementation in horses

Objectives were to evaluate effects of (1) repetitive arthrocentesis on biomarkers of inflammation (prostaglandin E(2), PGE(2)) and aggrecan synthesis (chondroitin sulfate-846; CS) in synovial fluid (SF); (2) exercise and superoxide dismutase (SOD) supplementation on biomarkers of inflammation, antioxidant status, and aggrecan synthesis, in horses. Preliminary trial. Standardbreds underwent four arthrocentesis procedures within 48 h and exhibited elevated CS and no changes in PGE(2). Exercise trial. this randomized crossover design used twelve Standardbred mares which received either treatment (3000 IU d(-1) oral SOD powder) or placebo (cellulose powder) for 6 wks which culminated with them running a repeated sprint exercise test (RSET). Samples were collected before (PRE), during (PEAK), and following exercise (POST). Exercise resulted in increased (P < 0.05) antioxidant defenses including erythrocyte SOD, total glutathione, glutathione peroxidase, gene transcripts for interferon-gamma, interleukin-10, and interleukin-1β in blood, and decreased plasma nitric oxide. Exercise increased (P < 0.05) SF CS and adjusted-PGE(2), and higher (P < 0.05) CS and PGE(2) were found in hock versus carpus joints. No treatment effects were detected. Results suggest normal adaptive responses likely due to exercise-induced tissue microdamage and oxidative stress. Additional research is needed to identify benefit(s) of SOD supplementation in horses.

Age-related differences in prostaglandin E2 synthesis by equine cartilage explants and synoviocytes

Time- and concentration-related actions of lipopolysaccharide (LPS) on the synthesis of prostaglandin E(2) (PGE(2)) were investigated in cartilage explants and synoviocytes harvested from 3 age groups of horses, all with clinically normal joint function: group A <10 years; group B 11-20 years and group C >20 years. Cartilage explants from group A horses were least and those from group C were most sensitive to LPS. Significant increases in PGE(2) concentration (P <or= 0.01) were obtained in group C horses in response to LPS concentrations of 1.0 microg/mL (and higher) after exposure for 24, 36 and 48 h, whereas explants from group A horses failed to respond to LPS at concentrations up to 100 microg/mL after exposure times up to 48 h. In contrast, synoviocytes from group A horses were most and those from group C horses were least sensitive to LPS stimulation. Synoviocytes from group A horses responded to LPS concentrations of 1 microg/mL (and higher) with significantly increased concentrations of PGE(2) at 24 and 36 h. Significant but numerically smaller increases in PGE(2) concentration were induced by LPS in synoviocytes from groups B and C. As the effects of high PGE(2) concentrations are catabolic for cartilage, these observations suggest that both synoviocytes and chondrocytes might exert roles in the degenerative changes which occur in cartilage in horses with osteoarthritis.

Influence of repeated arthrocentesis and exercise on synovial fluid concentrations of nitric oxide, prostaglandin E2 and glycosaminoglycans in healthy equine joints

REASONS FOR PERFORMING STUDY

The importance of osteoarthritis (OA) in the horse and the difficulty in its early diagnosis have led to a search for potential biomarkers of joint disease. If the levels of such markers are to be interpreted accurately, clinicians and researchers need to know whether they are influenced by environmental factors and/or interventions such as exercise and repeated arthrocentesis.

OBJECTIVE

To investigate the influence of repeated arthrocentesis and exercise on nitric oxide (NO), prostaglandin E2 (PGE2) and glycosaminoglycan (GAG) concentrations in synovial fluid (SF) from normal equine joints.

METHODS

SF was collected from the left metacarpophalangeal (MCP), radiocarpal and tarsocrural joints of 16 horses. Half of the horses were exercised and arthrocentesis was repeated 14, 14.5, 17 and 24 days after the start of the exercise programme, in both exercised and control horses. Nitric oxide was determined in SF from the MCP joint only and PGE2 and GAG concentrations were determined in SF from all joints.

RESULTS

Repeated arthrocentesis caused an increase in NO concentration in the MCP joint on Day 145, in PGE2 concentrations in the radiocarpal and tarsocrural joints on Day 145 and the release of GAGs into SF of the MCP and radiocarpal joints on Day 17. Exercise resulted in an increase in PGE2 levels in all joints but did not influence the other parameters measured.

POTENTIAL RELEVANCE

Repeated arthrocentesis is a potential confounding factor for the use of synovial NO, PGE2 and GAG concentrations as markers of joint disease. Based on this study, such a confounding effect can be avoided if one week or more separates arthrocentesis procedures. Moderate exercise causes a transient rise in PGE2 in SF.

The contribution of the synovium, synovial derived inflammatory cytokines and neuropeptides to the pathogenesis of osteoarthritis

Osteoarthritis (OA) is one of the most common and disabling chronic joint disorders affecting horses, dogs and humans. Synovial inflammation or synovitis is a frequently observed phenomenon in osteoarthritic joints and contributes to the pathogenesis of OA through formation of various catabolic and pro-inflammatory mediators altering the balance of cartilage matrix degradation and repair. Catabolic mediators produced by the inflamed synovium include pro-inflammatory cytokines, nitric oxide, prostaglandin E(2) and several neuropeptides, which further contribute to the pathogenesis of OA by increasing cartilage degradation. Recent studies suggest that substance P, corticotropin-releasing factor, urocortin and vasoactive intestinal peptide may also be involved in OA development, but the precise role of these neuropeptides in the pathogenesis of OA is not known. Since increased production of matrix metalloproteinases by the synovium is stimulated by pro-inflammatory cytokines, future anti-inflammatory therapies should focus on the synovium as a means of controlling subsequent inflammatory damage.

Equine osteoarthritis: a brief review of the disease and its causes

Degenerative joint diseases, such as osteoarthritis, adversely impact the health of the equine athlete as well as the economics of the equine industry. Our understanding of the aetiology of osteoarthritis, although not nearly exhaustive, has increased substantially in recent years. Molecules, including cytokines, inflammatory mediators, and metalloproteinases, have been identified and associated with the progression of joint disease. Several factors, including trauma to the joint, immobilization, conformation, shoeing, and ageing, have been linked with osteoarthritis. Our continued efforts into elucidating critical biological mediators and risk factors, coupled with better chondroprotective therapies and diagnostic tools, should facilitate our ability to maintain the skeletal health of the equine athlete

A type II-collagen derived peptide and its nitrated form as new markers of inflammation and cartilage degradation in equine osteochondral lesions

Markers of cartilage breakdown enable studying the degradation of cartilage matrix in equine joint pathologies. This study was designed to determine the levels of Coll2-1, a peptide of the triple helix of type II collagen, and Coll2-1NO(2), its nitrated form in the plasma of healthy horses (controls; n=37) and horses suffering from osteochondrosis (n=34). Clinical and arthroscopic scores were attributed reflecting the severity of lesions and were related to the plasma levels of Coll2-1 and Coll2-1NO(2). The median of Coll2-1 was significantly higher in the control group, whereas the mean of Coll2-1NO(2) showed significant elevation in the pathological group. However, the measurement means of scoring classes did not vary significantly. The markers were able to differentiate the group of horses suffering from osteochondrosis from the group of healthy horses. The elevation of Coll2-1NO(2) in the pathological group indicates an inflammation, mediated through reactive oxygen species and/or increased myeloperoxidase activity.

Evaluation of coexpression of microsomal prostaglandin E synthase-1 and cyclooxygenase-2 in interleukin-1- stimulated equine articular chondrocytes

OBJECTIVE

To characterize expression of cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1) and regulation of prostaglandin E2 (PGE2) production by equine articular chondrocytes.

SAMPLE POPULATION

Articular cartilage from the metacarpophalangeal joints of 7 adult horses.

PROCEDURE

Equine chondrocyte monolayer cultures were stimulated with different concentrations (2.5, 5, 10, and 20 ng/mL) of recombinant human interleukin-1beta (rhIL-1beta) for 24 hours and then with rhIL-1beta (5 ng/mL) for 3, 6, 9, 12, and 24 hours. Concentration of PGE2 in the media was measured via radioimmunoassay. Total RNA was extracted from harvested chondrocytes, and regulation of COX-2 and mPGES-1 mRNA was studied via reverse transcriptase-polymerase chain reaction assay and Southern blot analysis with equine-specific probes. Western blot analyses were performed on cellular extracts to characterize expression of COX-2 and mPGES-1 protein.

RESULTS

Stimulation with 5, 10, and 20 ng of rhIL-1beta/mL caused a significant increase in PGE2 concentrations in the culture media, and incubation of cells with rhIL-1beta (5 ng/mL) for 6 to 24 hours increased PGE2 production significantly. The increase in prostaglandin production was associated with an induction of COX-2 and mPGES-1 transcripts. There also was an rhIL-1beta-dependent induction in COX-2 and mPGES-1 protein expression.

CONCLUSIONS AND CLINICAL RELEVANCE

Collectively, results indicated that the rhIL-1beta-dependent increase in PGE2 production in equine chondrocytes in monolayer culture was associated with coordinated upregulation of COX-2 and mPGES-1 expression. The pathophysiologic consequences of upregulated COX-2 and mPGES-1 expression and of PGE2 synthesis in rhIL-1beta-stimulated equine chondrocytes remain to be elucidated.

Effects of the omega-3 fatty acid, α-linolenic acid, on lipopolysaccharide-challenged synovial explants from horses

OBJECTIVE

To determine the effects of pretreatment with alpha-linolenic acid, an omega-3 polyunsaturated fatty acid, on equine synovial explants challenged with lipopolysaccharide (LPS).

ANIMALS

8 mature mixed-breed horses (4 mares and 4 geldings).

PROCEDURE

Synovial explants were assigned to receive 1 of 7 concentrations of alpha-linolenic acid, ranging from 0 to 300 microg/mL. At each concentration, half of the explants were controls and half were challenged with 0.003 microg of LPS as a model of synovial inflammation. Cell inflammatory response was evaluated by measurement of prostaglandin E2 production via an ELISA. Synovial cell viability, function, histomorphologic characteristics, and cell membrane composition were evaluated by use of trypan blue dye exclusion, hexuronic acid assay for hyaluronic acid, objective microscopic scoring, and high-performance liquid chromatography, respectively.

RESULTS

Challenge with LPS significantly increased production of prostaglandin E2 and decreased production of hyaluronic acid. Treatment with alpha-linolenic acid at the highest dose inhibited prostaglandin E2 production. Cell viability and histomorphologic characteristics were not altered by treatment with alpha-linolenic acid or LPS challenge. Treatment with alpha-linolenic acid increased the percentage of this fatty acid in the explant cell membranes.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that investigation of alpha-linolenic acid as an anti-inflammatory medication for equine synovitis is warranted.

An experimental animal model of aseptic loosening of hip prostheses in sheep to study early biochemical changes at the interface membrane

BACKGROUND

Aseptic loosening of hip prosthesis as it occurs in clinical cases in human patients was attributed to wear particles of the implants, the response of the tissue dominated by macrophages and the production of inflammatory mediators and matrix degrading enzymes; however, the cascade of events initiating the process and their interaction regarding the time course is still open and discussed controversially. Therefore, the goal of this study was to establish an experimental animal model in sheep allowing to follow the cascade of early mechanical and biochemical events within the interface membrane and study the sequence of how they contribute to the pathological bone resorption necessary for aseptic loosening of the implant.

METHODS

A cemented modular system (Biomedtrix) was used as a hip replacement in 24 adult Swiss Alpine sheep, with one group receiving a complete cement mantle as controls (n = 12), and the other group a cement mantle with a standardized, lateral, primary defect in the cement mantle (n = 12). Animals were followed over time for 2 and 8.5 months (n = 6 each). After sacrifice, samples from the interface membranes were harvested from five different regions of the femur and joint capsule. Explant cell cultures were performed and supernatant of cultures were tested and assayed for nitric oxide, prostaglandin E2, caseinolytic and collagenolytic activity. RNA extraction and quantification were performed for inducible nitric oxide synthase, cyclooxygenase-2, interleukin 1, and interleukin 6. Overall differences between groups and time periods and interactions thereof were calculated using a factorial analysis of variance (ANOVA).

RESULTS

The development of an interface membrane was noticed in both groups at both time points. However, in the controls the interface membrane regressed in thickness and biological activity, while both variables increased in the experimental group with the primary cement mantle defect over time. Nitric oxide (NO) and PGE2 concentrations were higher in the 8.5 months group (P < 0.0001) compared to the 2 months group with a tendency for the unstable group to have higher concentrations. The same was true for collagenolytic activity (P = 0.05), but not for caseinolytic activity that decreased over time (P < 0.0001).

CONCLUSION

In this study, a primary cement mantle defect of the femoral shaft elicited biomechanical instability and biochemical changes over time in an experimental animal study in sheep, that resembled the changes described at the bone cement-interface in aseptic loosening of total hip prosthesis in humans. The early biochemical changes may well explain the pathologic bone resorption and formation of an interface membrane as is observed in clinical cases. This animal model may aid in future studies aiming at prevention of aseptic loosening of hip prosthesis and reflect some aspects of the pathogenesis involved.

Effects of ginger (Zingiber officinale Rosc.) on decreasing the production of inflammatory mediators in sow osteoarthrotic cartilage explants

The herbal remedy Zingiber officinale (ginger root) has been used for perhaps thousands of years in the Far East to treat inflammatory diseases, including osteoarthritis. However, the anti-arthritic effect of ginger root has never been evaluated on osteoarthrotic cartilage of sow. The objective of this study was to investigate the effects of ginger root extract (GRE) on the viability and the production of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) by sow osteoarthrotic cartilage explants. The cartilage explants (~20 mg/96-well plate) were grown in Ham's F-12/Dulbecco's Modified Eagle's Medium supplemented with 10% fetal bovine serum and antibiotics for 72 hours and depleted for 24 hours. GRE was then added at different concentrations (0-2,000 microg/mL), and the explants were allowed to grow for 24 hours. The cell viability was reduced (P<.05) with GRE >/=500 microg/mL, whereas it was not affected with GRE <100 microg/mL. In a follow-up experiment, the supernatants of cartilage explants with GRE (0-500 microg/mL) in the presence of interleukin-1beta (2 ng/mL), tumor necrosis factor-alpha (1 ng/mL), and lipopolysaccharides (10 microg/mL) were used to measure NO and PGE production. Increasing GRE concentration (1-100 microg/mL) reduced (P <.05) NO production by cartilage tissue explants, and a similar pattern was observed in the production of PGE(2). The inhibitory effects of GRE on NO and PGE(2) production by sow osteoarthrotic cartilage explants observed in this study suggest an important role for GRE as an anti-arthritic agent in osteoarthrosis in the sow.

Plasma and synovial fluid endothelin-1 and nitric oxide concentrations in horses with and without joint disease

OBJECTIVE

To compare plasma and synovial fluid endothelin-1 (ET-1) and nitric oxide (NO) concentrations in clinically normal horses and horses with joint disease.

ANIMALS

36 horses with joint disease, and 15 horses without joint disease.

PROCEDURE

Horses with joint disease were assigned to 1 of the 3 groups (ie, synovitis, degenerative joint disease [DJD], or joint sepsis groups) on the basis of findings on clinical and radiographic examination and synovial fluid analysis. Endothelin-1 and NO concentrations were measured in plasma from blood samples, collected from the jugular vein and ipsilateral cephalic or saphenous vein of the limb with an affected or unaffected joint, as well as in synovial fluid samples obtained via arthrocentesis from the involved joint.

RESULTS

Plasma ET-1 concentrations between affected and unaffected groups were not significantly different. Median concentration and concentration range of ET-1 in synovial fluid obtained from the joint sepsis group (35.830 pg/mL, 7926 to 86.614 pg/mL; n = 7) were significantly greater than values from the synovitis (17.531 pg/mL, 0.01 to 46.908 pg/mL; 18), DJD (22.858 pg/mL, 0.01 to 49.990 pg/mL; 10), and unaffected (10.547 pg/mL, 0.01 to 35.927 pg/mL; 10) groups. Plasma and synovial fluid NO concentrations between affected and unaffected groups were not significantly different.

CONCLUSIONS AND CLINICAL RELEVANCE

Endothelin-1 is locally synthesized in the joints of horses with various types of joint disease. Synovial fluid concentrations of ET-1 varied among horses with joint disease, with concentrations significantly higher in the synovial fluid of horses with joint sepsis. These results indicate that ET-1 may play a role in the pathophysiologic mechanism of joint disease in horses.

Inhibition of articular cartilage degradation by glucosamine-HCl and chondroitin sulphate

Glucosamine and chondroitin sulphate in many animal and human trials has improved joint health. In vitro studies are beginning to clarify their mode of action. The objective of this research was to: 1) determine at what concentrations glucosamine-HCl (GLN) and/or chondroitin sulphate (CS) would inhibit the cytokine-induced catabolic response in equine articular cartilage explants and 2) to determine if a combination of the 2 was more effective at inhibiting the catabolic response than the individual compounds. Articular cartilage was obtained from carpal joints of horses (age 1-4 years). Cartilage discs (3.5 mm) were biopsied and cultured. Explants were incubated with lipopolysaccharide (LPS) in the presence of varying concentrations of GLN, CS, or both. Control treatments included explants with no LPS and LPS without GLN or CS. Media were analysed for nitric oxide (NO), prostaglandin E2 (PGE2) and keratan sulphate. Cartilage was extracted for analysis of metalloproteinases (MMP). Four experiments were conducted. In all experiments, GLN at concentrations as low as 1 mg/ml decreased NO production relative to LPS stimulated cartilage without GLN over the 4 day period. In general, CS at either 0.25 or 0.5 mg/ml did not inhibit NO production. The addition of CS to GLN containing media did not further inhibit NO production. GLN at concentrations as low as 0.5 mg/ml decreased PGE2 production, whereas CS did not effect on PGE2. The combination of GLN/CS decreased MMP-9 gelatinolytic activity but had no effect on MMP-2 activity. The combination in 2 experiments tended to decrease MMP-13 protein concentrations and decreased keratan sulphate levels in media. Overall, the combination of GLN (1 mg/ml) and CS (0.25 mg/ml) inhibited the synthesis of several mediators of cartilage degradation. These results further support the effort to understand the role of GLN and CS in preserving articular cartilage in athletic horses.

In vitro studies of a photo-oxidized bovine articular cartilage

Bovine articular cartilage was photo-oxidized and cultured with native articular bovine cartilage and synovial membrane to study the interaction between these tissues mimicking the physiological situation in the joint. The photo-oxidation was applied as a pretreatment of cartilage for future use in cartilage resurfacing procedures in joints. Properties of the transplant were assessed by testing the production of local mediators, such as nitric oxide (NO) and prostaglandin E2 (PGE2), and neutral metalloproteinase activities under normal conditions and after stimulation with various stimulants representative of inflammatory changes in pathophysiological conditions. Unlike normal cartilage photo-oxidized cartilage did not release significant amounts of NO and PGE2 and showed less gelatinolytic and caseinolytic activity compared to native bovine articular cartilage. Enzyme activity of the combined cultures was at a level intermediate between that of photo-oxidized cartilage and native cartilage cultures alone. In contrast to normal cartilage, living chondrocytes were not visible in photo-oxidized cartilage using live/dead staining. These results indicate, that the photo-oxidized cartilage may have a beneficial effect on adjacent native host cartilage and therefore be a suitable transplant for use in in vivo experiments.