Inflammation in joint injury and post-traumatic osteoarthritis.

Inflammation is a variable feature of osteoarthritis (OA), associated with joint symptoms and progression of disease. Signs of inflammation can be observed in joint fluids and tissues from patients with joint injuries at risk for development of post-traumatic osteoarthritis (PTOA). Furthermore, inflammatory mechanisms are hypothesized to contribute to the risk of OA development and progression after injury. Animal models of PTOA have been instrumental in understanding factors and mechanisms involved in chronic progressive cartilage degradation observed after a predisposing injury. Specific aspects of inflammation observed in humans, including cytokine and chemokine production, synovial reaction, cellular infiltration and inflammatory pathway activation, are also observed in models of PTOA. Many of these models are now being utilized to understand the impact of post-injury inflammatory response on PTOA development and progression, including risk of progressive cartilage degeneration and development of chronic symptoms post-injury. As evidenced from these models, a vigorous inflammatory response occurs very early after joint injury but is then sustained at a lower level at the later phases. This early inflammatory response contributes to the development of PTOA features including cartilage erosion and is potentially modifiable, but specific mediators may also play a role in tissue repair. Although the optimal approach and timing of anti-inflammatory interventions after joint injury are yet to be determined, this body of work should provide hope for the future of disease modification tin PTOA.

Synovial chemokine expression and relationship with knee symptoms in patients with meniscal tears.

OBJECTIVE: In patients with knee OA, synovitis is associated with knee pain and symptoms. We previously identified synovial mRNA expression of a set of chemokines (CCL19, IL-8, CCL5, XCL-1, CCR7) associated with synovitis in patients with meniscal tears but without radiographic OA. CCL19 and CCR7 were also associated with knee symptoms. This study sought to validate expression of these chemokines and association with knee symptoms in more typical patients presenting for meniscal arthroscopy, many who have pre-existing OA. DESIGN: Synovial fluid (SF) and biopsies were collected from patients undergoing meniscal arthroscopy. Synovial mRNA expression was measured using quantitative RT-PCR. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was administered preoperatively. Regression analyses determined if associations between chemokine mRNA levels and KOOS scores were independent of other factors including radiographic OA. CCL19 in SF was measured by ELISA, and compared to patients with advanced knee OA and asymptomatic organ donors. RESULTS: 90% of patients had intra-operative evidence of early cartilage degeneration. CCL19, IL-8, CCL5, XCL1, CCR7 transcripts were detected in all patients. Synovial CCL19 mRNA levels independently correlated with KOOS Activities of Daily Living (ADL) scores (95% CI [-8.071, -0.331], P = 0.036), indicating higher expression was associated with more knee-related dysfunction. SF CCL19 was detected in 7 of 10 patients, compared to 4 of 10 asymptomatic donors. CONCLUSION: In typical patients presenting for meniscal arthroscopy, synovial CCL19 mRNA expression was associated with knee-related difficulty with ADL, independent of other factors including presence of radiographic knee OA.

The influence of synovial inflammation and hyperplasia on symptomatic outcomes up to 2 years post-operatively in patients undergoing partial meniscectomy.

OBJECTIVE: Synovitis is associated with pain and other symptoms in patients with knee osteoarthritis (OA), and in patients with meniscal tears even in the absence of radiographic OA. Patients undergoing arthroscopic partial meniscectomy were followed for 2 years to determine whether synovitis predicts post-operative symptoms. DESIGN: Thirty-three patients scheduled for arthroscopy were recruited for this pilot study. Symptoms were assessed using a knee pain scale, the Lysholm score, and the short form-12 (SF-12(®)) pre-operatively and at 16 weeks, 1 year and 2 years post-operatively. Synovial inflammation and hyperplasia were graded on surgical biopsies. Linear mixed effects models were tested to determine whether inflammation or hyperplasia is associated with outcome scores over time. RESULTS: Lysholm scores and SF-12(®) physical component sub-scores were worse pre-operatively in patients with inflammation (Lysholm: 52.42 [95% confidence interval (CI) 42.37, 62.47] vs 72.38 [66.03, 78.72], P < 0.001; SF-12: 36.81 [28.26, 45.37] vs 46.23 [40.14, 52.32], P < 0.05). Up to 2-years post-operatively, patients with inflammation achieved mean scores similar to those without inflammation. As a result, the mean improvement in Lysholm scores was 13.01 [1.48-24.53] points higher than patients without inflammation, P = 0.03. 33% (4/12) of patients with inflammation still had fair to poor Lysholm scores 2 years after surgery compared to 7% (1/15, P=0.14) without inflammation. No association between hyperplasia and symptoms was noted. CONCLUSIONS: In this pilot study of patients undergoing partial meniscectomy, synovial inflammation was associated with worse pre-operative symptoms, but not with poorer outcomes in the first 2 years post-arthroscopy. Larger cohorts and longer follow-up should be pursued to confirm this relationship, and determine if the initial response is sustained.

Local cytokine profiles in knee osteoarthritis: elevated synovial fluid interleukin-15 differentiates early from end-stage disease.

OBJECTIVE: Much of what is known about the inflammatory response in the synovial membrane (SM) of patients with osteoarthritis (OA) comes from studies of synovial tissues from end-stage disease. In this study, we sought to better characterize the inflammatory infiltrate in symptomatic patients with early signs of knee OA, and to determine how inflammatory cell populations relate to the pattern of cytokine and degradative enzyme production. METHODS: Study populations comprised patients with degenerative meniscal tears and early cartilage thinning undergoing arthroscopic procedures (early OA) and patients undergoing total knee replacement for end-stage OA. Quantitative real-time polymerase chain reaction (PCR) was used to measure expression of SM cytokines and enzymes implicated in the pathogenesis of inflammatory arthritis and OA, as well as cell lineage-specific markers. We quantified synovial fluid (SF) cytokines and enzymes by enzyme-linked immunosorbent assay (ELISA) and SM cell populations by immunohistochemistry. RESULTS: We found increased levels of SF interleukin-15 (IL-15) protein in the early knee OA patients when compared to end-stage OA. Both SF IL-15 protein and numbers of CD8 cells within SM correlated with matrix metalloproteinase-1 (MMP-1) and three levels. TNF-alpha, IL-6 and IL-21 were also detectable in the SF of the majority of patients, and IL-15 levels were associated with IL-6 levels. CONCLUSION: IL-15 is elevated in early knee OA, suggesting activation of an innate immune response in the SM. The association of IL-15 expression with CD8 transcripts and MMPs implicates this cytokine in OA pathogenesis and as a candidate therapeutic target.

Elevated high-sensitivity C-reactive protein levels are associated with local inflammatory findings in patients with osteoarthritis.

OBJECTIVE: C-reactive protein (CRP) has been associated with disease progression in patients with osteoarthritis (OA), but the reasons for this remain unclear. We hypothesized that higher CRP would be related to local inflammatory findings in the joints of patients with OA. METHODS: Plasma and synovial membrane specimens from 54 OA patients undergoing total hip or knee arthroplasty or arthroscopy were obtained. Synovial fluid was obtained from 25 of these patients. Hematoxylin and eosin stained synovial membrane sections were scored for degree of inflammatory cell infiltration. Plasma high-sensitivity CRP (hsCRP) levels, and serum and synovial fluid interleukin (IL)-6 and IL-1beta levels were measured by enzyme-linked immunosorbent assay. RESULTS: Fifty-seven percent of patients with idiopathic OA had inflammatory infiltrates within the synovial membrane. The mean hsCRP level in patients with inflammatory infiltrates was significantly higher than those without inflammation (4.7 +/- 5.0 mg/L vs 1.7 +/- 3.6 mg/L, P = 0.003). There were significant correlations between hsCRP levels and synovial fluid IL-6 (r = 0.64, P = 0.0006), degree of synovial inflammatory infiltration (r = 0.43, P = 0.002), and body mass index (r = 0.31, P = 0.02). Multivariate analysis indicated that only degree of inflammatory infiltrate was significantly associated with hsCRP level (P = 0.026). CONCLUSION: These results suggest that systemic hsCRP levels reflect synovial inflammation in OA patients, perhaps by means of synovial IL-6 production. Future studies are needed to clarify how these infiltrates and their products may contribute to disease pathogenesis.

Interleukin-12 is expressed by infiltrating macrophages and synovial lining cells in rheumatoid arthritis and osteoarthritis.

TH1 cytokines have recently been detected in rheumatoid arthritis (RA) and osteoarthritis (OA). For this reason we studied the TH-1-promoting cytokine IL-12 in synovial membranes from patients with RA and OA. IL-12 transcripts and protein were analyzed by reverse transcriptase-polymerase chain reaction (PCR) and immunohistochemistry, respectively. In addition, IL-12 transcripts were quantitated by competitive PCR. IL-12 transcripts (p40) were detected in 8 of 13 patients with RA and in 10 of 18 patients with OA. Their levels did not differ significantly between RA and OA. IL-12 heterodimer protein was detected by immunostaining using an anti-IL-12p70 mAb. Double labeling with anti-IL-12p70 and anti-CD68 mAbs showed that synovial lining cells and monocytes/macrophages expressed IL-12 p70 protein. The presence of IL-12 p70 protein in the synovial membranes of patients with RA and OA suggests that IL-12 may play an important immunoregulatory role in these diseases by perpetuating inflammation.

Serotonergic recovery after (+/-)3,4-(methylenedioxy) methamphetamine injury: observations in rats.

(+/-)-3,4-Methylenedioxymethamphetamine (MDMA) is a recreational drug of abuse which damages serotonin (5-HT) neurons in animals. In monkeys, the damage appears to be permanent. By contrast, in rats there is indication that neuronal recovery takes place, although there is question as to whether the recovery is sustained. The purpose of the present study was to examine the fate of 5-HT neurons in MDMA-treated rats, and to compare findings in the rat with those in the monkey. Rats were treated with MDMA (10 mg/kg i.p.) every 2 hr for a total dose of 40 mg/kg. Two, 8, 16, 32 and 52 weeks later, groups (n = 8) of MDMA-treated rats, along with age-matched controls (n = 8), were analyzed for regional brain 5-HT, 5-hydroxyindoleacetic acid and [3H]paroxetine-labeled 5-HT uptake sites. Two weeks after MDMA, 5-HT neuronal markers were reduced markedly. Reductions ranged from 42 to 82% depending on brain region. By 16 weeks, there was evidence of recovery in some brain regions (e.g., hypothalamus and striatum) and by 32 weeks, recovery was nearly complete in most brain regions examined. One year after MDMA, recovery was still evidence in all brain regions evaluated, although closer inspection of the group data revealed that whereas most MDMA-treated rats recovered, some did not. These few animals had severe and enduring serotonergic deficits in multiple brain regions. Morphologic immunocytochemical studies yielded results which corroborated the neurochemical findings.(ABSTRACT TRUNCATED AT 250 WORDS)