Evidencia de mecanismos inflamatorios en la osteoartritis

Effect of smoking on the redox status of knee osteoarthritis: A preliminary study

Even though smoking has been scarcely studied in osteoarthritis (OA) etiology, it is considered a controversial risk factor for the disease. Exposure to tobacco smoke has been reported to promote oxidative stress (OS) as part of the damage mechanism. The aim of this study was to assess whether smoking increases cartilage damage through the generation of OS. Peripheral blood (PB) and synovial fluid (SF) samples from patients with OA were analyzed. The samples were stratified according to smoking habit, Kellgren-Lawrence score, pain, and cotinine concentrations in PB. Malondialdehyde (MDA), methylglyoxal (MGO), advanced protein oxidation products (APOPs), and myeloperoxidase (MPO) were assessed; the activity of antioxidant enzymes such as gamma-glutamyl transferase (GGT), glutathione S-transferase (GST) and catalase (CAT), as well as the activity of arginase, which favors the destruction of cartilage, was determined. When stratified by age, for individuals <60 years, the levels of MDA and APOPs and the activity of MPO and GST were higher, as well as antioxidant system activity in the smoking group (OA-S). A greater degree of pain in the OA-S group increased the concentrations of APOPs and arginase activity (P < 0.01 and P < 0.05, respectively). Arginase activity increased significantly with a higher degree of pain (P < 0.01). Active smoking can be an important risk factor for the development of OA by inducing systemic OS in young adults, in addition to reducing antioxidant enzymes in older adults and enhancing the degree of pain and loss of cartilage.

IL-37 is associated with osteoarthritis disease activity and suppresses proinflammatory cytokines production in synovial cells

The objective of this study is to investigate the correlation between IL-37 level and osteoarthritis activity and to determine the anti-inflammatory effects of IL-37 in peripheral blood mononuclear cells (PBMCs) and synovial cells (SCs) from osteoarthritis (OA) patients, which including 32 patients with erosive inflammatory OA (EIOA) and 40 patients with primary generalized OA (PGOA), 40 age and sex matched healthy volunteers were recruited as healthy controls (HCs). The protein and relative mRNA levels of IL-37 were significant increased in the blood of EIOA patients compared with those of PGOA patients and HCs. Serum IL-37 levels of OA patients were positively correlated with VAS score, as well as with CRP, ESR in blood. Positive correlations were also observed among IL-37 with IL-1β, TNF-α and IL-6 in synovial cells. Furthermore, the expression of IL-1β, TNF-α and IL-6 in PBMCs and SCs from EIOA patients was suppressed by IL-37 in vitro. In conclusion, our results indicated that IL-37 increased in EIOA patients and was positively correlated with disease activity, the pro-inflammatory cytokines such as IL-1β, TNF-α and IL-6 in PBMCs and synovial cells from EIOA patients were restrained by recombinant IL-37. Thus, IL-37 may serve as a novel therapeutic target for the treatment of OA inflammation.

Mitochondrial respiratory chain dysfunction modulates metalloproteases -1, -3 and -13 in human normal chondrocytes in culture

BACKGROUND

Mitochondrion has an important role in the osteoarthritis (OA) pathology. We have previously demonstrated that the alteration of the mitochondrial respiratory chain (MRC) contributes to the inflammatory response of the chondrocyte. However its implication in the process of cartilage destruction is not well understood yet. In this study we have investigated the relationship between the MRC dysfunction and the regulation of metalloproteases (MMPs) in human normal chondrocytes in culture.

METHODS

Human normal chondrocytes were isolated from human knees obtained form autopsies of donors without previous history of rheumatic disease. Rotenone, 3-Nitropropionic acid (NPA), Antimycin A (AA), Sodium azide and Oligomycin were used to inhibit the activity of the mitochondrial complexes I, II, III, IV and V respectively. The mRNA expression of MMPs -1, -3 and -13 was studied by real time PCR. The intracellular presence of MMP proteins was evaluated by western blot. The liberation of these proteins to the extracellular media was evaluated by ELISA. The presence of proteoglycans in tissue was performed with tolouidin blue and safranin/fast green. Immunohistochemistry was used for evaluating MMPs on tissue.

RESULTS

Firstly, cells were treated with the inhibitors of the MRC for 24 hours and mRNA expression was evaluated. An up regulation of MMP-1 and -3 mRNA levels was observed after the treatment with Oligomycin 5 and 100 μg/ml (inhibitor of the complex V) for 24 hours. MMP-13 mRNA expression was reduced after the incubation with AA 20 and 60 μg/ml (inhibitor of complex III) and Oligomycin. Results were validated at protein level observing an increase in the intracellular levels of MMP-1 and -3 after Oligomycin 25 μg/ml stimulation [(15.20±8.46 and 4.59±1.83 vs. basal=1, respectively (n=4; *P<0.05)]. However, AA and Oligomycin reduced the intracellular levels of the MMP-13 protein (0.70±0.16 and 0.3±0.24, respectively vs. basal=1). In order to know whether the MRC dysfunction had an effect on the liberation of MMPs, their levels were evaluated in the supernatants. After 36 hours of stimulation, values were: MMP-1=18.06±10.35 with Oligomycin 25 μg/ml vs. basal=1, and MMP-3=8.49±4.32 with Oligomycin 5 μg/ml vs. basal=1 (n=5; *P<0.05). MMP-13 levels in the supernatants were reduced after AA 60 μg/ml treatment (0.50±0.13 vs. basal=1) and Oligomycin 25 μg/ml (0.41±0.14 vs. basal=1); (n=5; *P<0.05). The treatment of explants with Oligomycin, showed an increase in the positivity of MMP-1 and -3. Explants stimulated with AA or Oligomycin revealed a decrease in MMP-13 expression. Proteoglycan staining demonstrated a reduction of proteoglycan levels in the tissues treated with Oligomycin.

CONCLUSIONS

These results reveal that MRC dysfunction modulates the MMPs expression in human normal chondrocytes demonstrating its role in the regulation of the cartilage destruction.

[Changes in synovial fluid in different knee-joint diseases]

OBJECTIVE

To analyse the changes in synovial fluid (SF) in the most common knees joint diseases, and to establish a relationship according to its concentration.

MATERIAL AND METHODS

A total of 62 synovial fluids were analysed from knees with, meniscus disease (32), anterior cruciate ligament (ACL) (17) and isolated chondral injury (13). A quantitative and quality study was performed on each sample, which included cytokines IL-1, IL-2, IL-6, IL-10, TNF-α, and growth factors, IGF-1 and TGF-ß).

RESULTS

The SF environment in the ACL injury was mainly anabolic and inflammatory, with increased levels of IL1, IL6, significant levels of TGF-ß (P=.02 and P=.004), IL-10 (P=.046 and P=.047) and significantly decreased levels of TNF-α (P=.02 and P=.004). There was mainly a catabolic environment in chondral and meniscal disease, with a significant increase in TNF-α and a significant decrease in TGF-ß (P=.02 and P=.004). The differences were greater in the case of isolated chondral injury.

CONCLUSION

The changes observed show that, as well as the biomechanical changes, the SF has a negative effect on joint homeostasis, it composition varying depending on the type of pathology.