Objective. To examine the role of tumor necrosh factor a (TNF'a), interleukin-la (IL-la), and IL-lf? in collagen-induced arthritis (CIA), immediately after onset and during the phase of established arthritis.Methods. Male DBAA mice with collageninduced arthritis were treated with antibodies against murine TNFa and I L -l d p at different time points of the disease. IL-1 receptor antagonist (IL-1Ra) was administered using Abet osmotic minipumps. The effect of anticytokine treatment was monitored by visual scoring. Histology and cytokine reverse transcription polymerase chain reaction (RT-PCR) analyses were performed at the end of the treatment period.Results. Anti-TNFa treatment showed efficacy shortly after onset of the disease, but had little effect on fully established CIA. Histologic analysis after early treatment revealed that anti-TNFa significantly reduced joint pathology, as determined by infiltration of inflammatory cells and cartilage damage. Anti-IL-1 dfl treatment ameliorated both early and full-blown CIA. This clear suppression of established arthritis was confirmed by administration of high doses of IL-1Ra. Dose-response experiments showed that a continuous supply of 1 mg/day was needed for optimal suppression. Histologic analysis showed markedly reduced cartilage destruction both in the knee and the ankle joints. Autoradiography demonstrated full recovery of chondrocyte synthetic function of articular cartilage. In

IL-32 is a recently discovered cytokine that induces TNF␣, IL-1␤, IL-6, and chemokines. We investigated whether IL-32 is expressed in the synovia of patients with rheumatoid arthritis (RA) and studied associations with disease severity and the presence of other cytokines. Immunohistochemistry revealed that IL-32 is highly expressed in RA synovial tissue biopsies, whereas IL-32 was not observed in synovial tissues from patients with osteoarthritis. Moreover, in synovial biopsies from 29 RA patients with active disease, the level of IL-32 staining correlated with erythrocyte sedimentation rate, a marker of systemic inflammation (R ‫؍‬ 0.63 and P < 0.0003). Synovial staining of IL-32 also correlated with indices of synovial inflammation (R ‫؍‬ 0.80 and P < 0.0001) as well as synovial presence of TNF␣ (R ‫؍‬ 0.68 and P < 0.004), IL-1␤ (R ‫؍‬ 0.79 and P < 0.0001), and IL-18 (R ‫؍‬ 0.82 and P < 0.001). IL-32 was a potent inducer of prostaglandin E2 release in mouse macrophages and human blood monocytes, an important property for inflammation. After the injection of human IL-32␥ into the knee joints of naïve mice, joint swelling, with pronounced influx of inflammatory cells and cartilage damage, was observed. In TNF␣-deficient mice, IL-32-driven joint swelling was absent and cell influx was markedly reduced, but loss of proteoglycan was unaffected, suggesting that IL-32 activity is, in part, TNF␣-dependent. IL-32, strongly associated with TNF␣, IL-1␤, and IL-18, appears to play a role in human RA and may be a novel target in autoimmune diseases.autoimmune ͉ inflammation ͉ tumor necrosis factor

T cell IL-17 displays proinflammatory properties and is expressed in the synovium of patients with rheumatoid arthritis. Its contribution to the arthritic process has not been identified. Here, we show that blocking of endogenous IL-17 in the autoimmune collagen-induced arthritis model results in suppression of arthritis. Also, joint damage was significantly reduced. In contrast, overexpression of IL-17 enhanced collagen arthritis. Moreover, adenoviral IL-17 injected in the knee joint of type II collagen-immunized mice accelerated the onset and aggravated the synovial inflammation at the site. Radiographic and histologic analysis showed markedly increased joint destruction. Elevated levels of IL-1β protein were found in synovial tissue. Intriguingly, blocking of IL-1αβ with neutralizing Abs had no effect on the IL-17-induced inflammation and joint damage in the knee joint, implying an IL-1 independent pathway. This direct potency of IL-17 was underscored in the unabated IL-17-induced exaggeration of bacterial cell wall-induced arthritis in IL-1β−/− mice. In conclusion, this data shows that IL-17 contributes to joint destruction and identifies an IL-1-independent role of IL-17. These findings suggest IL-17 to be a novel target for the treatment of destructive arthritis and may have implications for tissue destruction in other autoimmune diseases.

This is the first report that oral delivery of BMEVs ameliorates experimental arthritis and this warrants further research to determine whether this beneficial effect can be seen in rheumatoid arthritis patients.

This study shows that overexpression of active TGF-beta1 in the knee joint results in OA-like changes and suggests the synovial lining cells contribute to the chondro-osteophyte formation.

ScopeExtracellular vesicles, including exosomes, have been identified in all biological fluids and rediscovered as an important part of the intercellular communication. Breast milk also contains extracellular vesicles and the proposed biological function is to enhance the antimicrobial defense in newborns. It is, however, unknown whether extracellular vesicles are still present in commercial milk and, more importantly, whether they retained their bioactivity. Here, we characterize the extracellular vesicles present in semi-skimmed cow milk available for consumers and study their effect on T cells.Methods and ResultsExtracellular vesicles from commercial milk were isolated and characterized. Milk-derived extracellular vesicles contained several immunomodulating miRNAs and membrane protein CD63, characteristics of exosomes. In contrast to RAW 267.4 derived extracellular vesicles the milk-derived extracellular vesicles were extremely stable under degrading conditions, including low pH, boiling and freezing. Milk-derived extracellular vesicles were easily taken up by murine macrophages in vitro. Furthermore, we found that they can facilitate T cell differentiation towards the pathogenic Th17 lineage. Using a (CAGA)12-luc reporter assay we showed that these extracellular vesicles carried bioactive TGF-β, and that anti-TGF-β antibodies blocked Th17 differentiation.ConclusionOur findings show that commercial milk contains stable extracellular vesicles, including exosomes, and carry immunoregulatory cargo. These data suggest that the extracellular vesicles present in commercial cow milk remains intact in the gastrointestinal tract and exert an immunoregulatory effect.

The IL-1R/Toll-like receptor (TLR) superfamily of receptors has a key role in innate immunity and inflammation. In this study, we report that streptococcal cell wall (SCW)-induced joint inflammation is predominantly dependent on TLR-2 signaling, since TLR-2-deficient mice were unable to develop either joint swelling or inhibition of cartilage matrix synthesis. Myeloid differentiation factor 88 (MyD88) is a Toll/IL-1R domain containing adaptor molecule known to have a central role in both IL-1R/IL-18R and TLR signaling. Mice deficient for MyD88 did not develop SCW-induced arthritis; both joint swelling and disturbance of cartilage chondrocyte anabolic function was completely abolished. Local levels of proinflammatory cytokines and chemokines in synovial tissue washouts were strongly reduced in MyD88-deficient mice. Histology confirmed the pivotal role of MyD88 in acute joint inflammation. TLR-2-deficient mice still allow influx of inflammatory cells into the joint cavity, although the number of cells was markedly reduced. No influx of inflammatory cells was seen in joints of MyD88-deficient mice. In addition, cartilage matrix proteoglycan loss was completely absent in MyD88 knockout mice. These findings clearly demonstrated that MyD88 is a key component in SCW-induced joint inflammation. Since agonists of the Toll-like pathway are abundantly involved in both septic and rheumatoid arthritis, targeting of MyD88 may be a novel therapy in inflammatory joint diseases.

Increasing epidemiologic evidence supports a link between periodontitis and rheumatoid arthritis. The actual involvement of periodontitis in the pathogenesis of rheumatoid arthritis and the underlying mechanisms remain, however, poorly understood. We investigated the influence of concomitant periodontitis on clinical and histopathologic characteristics of T cell–mediated experimental arthritis and evaluated modulation of type II collagen (CII)–reactive Th cell phenotype as a potential mechanism. Repeated oral inoculations of periodontal pathogens Porphyromonas gingivalis and Prevotella nigrescens induced periodontitis in mice, as evidenced by alveolar bone resorption. Interestingly, concurrent periodontitis induced by both bacteria significantly aggravated the severity of collagen-induced arthritis. Exacerbation of arthritis was characterized by increased arthritic bone erosion, whereas cartilage damage remained unaffected. Both P. gingivalis and P. nigrescens skewed the CII-specific T cell response in lymph nodes draining arthritic joints toward the Th17 phenotype without affecting Th1. Importantly, the levels of IL-17 induced by periodontal pathogens in CII-specific T cells directly correlated with the intensity of arthritic bone erosion, suggesting relevance in pathology. Furthermore, IL-17 production was significantly correlated with periodontal disease–induced IL-6 in lymph node cell cultures. The effects of the two bacteria diverged in that P. nigrescens, in contrast to P. gingivalis, suppressed the joint-protective type 2 cytokines, including IL-4. Further in vitro studies showed that the Th17 induction strongly depended on TLR2 expression on APCs and was highly promoted by IL-1. Our data provide evidence of the involvement of periodontitis in the pathogenesis of T cell–driven arthritis through induction of Ag-specific Th17 response.