IL-1β In Fibroblast-like Synoviocytes Research Articles

The therapeutic effects of lipoxin A4 during treadmill exercise on monosodium iodoacetate-induced osteoarthritis in rats

Lipoxin A4 (LXA4), a kind of adipokines, is a potent stop signal of inflammation. Our preliminary study found that LXA4 of serum and intra-articular lavage fluid (IALF) was rapidly elevated in 2 h and rapidly reduced to normal level at 4 h after moderate-intensity treadmill exercise. The aim was to confirm the therapeutic effects of LXA4 during treadmill exercise on rat model of monosodium iodoacetate (MIA)-induced OA and the detailed mechanism of LXA4 on OA. One hundred and twenty-four male Sprague-Dawley rats were submitted to two different protocols. A single session of treadmill exercise: sixty-four rats were randomly divided into treadmill exercise of different intensities for 60 min only once (n = 4). Formal treadmill exercise: sixty rats were randomly divided into six groups (n = 10): control group (CG), knee OA group (OAG), OA with treadmill exercise of different intensities (OAL, OAM and OAH), and OAM + BOC-2 (an antagonist of LXA4 receptor). The rats were evaluated by ELISA, histology, immunohistochemistry and western blotting. Fibroblast-like synoviocytes (FLSs) were obtained from knee joint of rats. The effects of LXA4 on interleukin (IL)-1β induced FLSs were evaluated by western blotting and immunofluorescence. The results of ELISA, histological evaluation, western blotting and immunohistochemistry indicated that OAM had a better treatment which could be suppressed by BOC-2. Moreover, LXA4 could attenuate the expression of matrix metalloproteinase (MMP)-3 and MMP-13 and suppress the expression of nuclear factor-kappa B (NF-κB) p65 induced by IL-1β in FLSs. The therapeutic effects of LXA4 during treadmill exercise on MIA-induced OA via inhibiting NF-κB signaling pathway.

GATA4 regulates angiogenesis and persistence of inflammation in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by abnormal inflammation, angiogenesis, and cartilage destruction. In RA, neoangiogenesis is an early and crucial event to promote the formation of pannus, causing further inflammatory cell infiltration. The transcription factor GATA4 is a critical regulator of cardiac differentiation-specific gene expression. We find that a higher level of GATA4 exists in synovium of rheumatoid arthritis (RA) patients, but the function of GATA4 in RA remains unclear. In the present study, IL-1β induces inflammation in fibroblast-like synoviocytes (FLS) MH7A, which is accompanied with the increased expression of GATA4 and VEGF production. Through application of GATA4 loss-of-function assays, we confirm the requirement of GATA4 expression for inflammation induced by IL-1β in FLS. In addition, we demonstrate for the first time that GATA4 plays key roles in regulating VEGF secretion from RA FLS to promote cellular proliferation, induce cell migration, and angiogenic tube formation of endothelial cells. GATA4 induces the angiogenic factors VEGFA and VEGFC, by directly binding to the promoter and enhancing transcription. The knockdown of GATA4 attenuates the development of collagen-induced arthritis (CIA) and prevents RA-augmented angiogenesis in vivo, which are accompanied with decreased VEGF level. These results reveal a previously unrecognized function for GATA4 as a regulator of RA angiogenesis and we provide experimental data validating the therapeutic target of GATA4 in RA mice.

Role of the NLRP3 inflammasome in the transient release of IL-1β induced by monosodium urate crystals in human fibroblast-like synoviocytes.

BackgroundTo investigate whether monosodium urate (MSU) crystals induce interleukin (IL)-1β in human fibroblast-like synoviocytes (FLS), and whether the NLRP3 inflammasome is involved in the inflammatory mechanism.MethodsHuman FLS isolated from explants of synovial tissue were stimulated with MSU crystals (0.001 to 0.5 mg/ml) for different time course (6 hours to 48 hours). The expressions of IL-1β, IL-6, TNF-α and NLRP3 were evaluated with ELISA, Western blot and quantitative real-time PCR.ResultsExposure of FLS to MSU crystals transiently induced a significant increase in IL-1β expression in culture medium with a peak at 6 h. The mRNA level of IL-1β in the FLS cells had a similar pattern at this time point. Changes in IL-6 and TNF-α expression were not observed. Simultaneously, intercellular pro-IL-1β was detected at 6 h. Furthermore, MSU crystals also induced NLRP3 mRNA and protein expression at 6 h to 48 h after MSU treatment.ConclusionsMSU crystals directly increased IL-1β and intercellular NLRP3 expression in FLS cells. It is suggested that the NLRP3 inflammasome may be associated with IL-1β in FLS treated with MSU. Altogether, MSU could induce production and release of IL-1β through the NLRP3 inflammasome in human synoviocytes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12950-015-0070-7) contains supplementary material, which is available to authorized users.

Characterization of an Ebosin derivative produced by heterologous gene replacement in Streptomyces sp. 139.

BackgroundEbosin is a novel exopolysaccharide (EPS) produced by Streptomyces sp. 139 and evidenced to possess an anti-rheumatic arthritis activity in vivo. The Ebosin biosynthesis gene cluster (ste) consists of 27 ORFs and ste7 has previously been demonstrated to code for a fucosyltransferase, which plays an essential role in the formation of repeating sugar units during Ebosin production. Aiming to generate derivatives of Ebosin for better activity, we replaced ste7 with a gene encoding for a glucosyltransferase (gtf) from Streptococcus thermophilus.ResultsThis alteration resulted in a novel Ebosin derivative (EPS-7 g) with its monosaccharide composition dramatically changed, especially in the proportion of glucose which increased from 1.1% (Ebosin) to 84.01% (EPS-7 g). In an ELISA analysis, EPS-7 g exhibited a higher binding activity for IL-1R, as a competitor of interleukin-1, than that of Ebosin. It also exhibited a higher inhibitory effect on the activity of IL-1β-converting enzyme and production of IL-1β in fibroblast-like synoviocytes (FLS). In addition, experiments with acute inflamed mice induced by croton oil showed a significantly higher anti-inflammatory activity of EPS-7 g compared with Ebosin.ConclusionsThe new Ebosin derivative EPS-7 g is more bioactive than Ebosin evaluated by a series of experiments. This is the first report demonstrating a modification of EPS structure via heterologous gene replacement in Streptomyces.

Decreased induction of IL-1β in fibroblast-like synoviocytes: A possible regulatory mechanism maintaining joint homeostasis

The response of fibroblast-like synoviocytes (FLS) to inflammatory stimuli was compared to their, respectively, derived dermal fibroblasts (DF) to determine whether regulatory controls exist within FLS to insure normal joint homeostasis. We further analyzed whether the loss of the normal regulatory controls present within the FLS could predispose to the development of non-rheumatic joint disease (non-RA). Primary fibroblast cell lines were generated from synovial and skin tissue from ten rheumatoid arthritis (RA) and ten non-RA patients. Cell lines were pulse labeled with [ 35S]-methionine and stimulated with TNFα or IL-1β. Protein synthesis of IL-1β, IL-6 and IL-8 was quantitated following immunoprecipitation. Gene expression was determined by Northern blot analysis. We noted, IL-1β was minimally detected in FLS under nonstimulated conditions. In response to stimulation with IL-1β or TNFα, production of IL-1β was found to be 3.5 and 5-fold lower in FLS, respectively, when compared to DF from the same individual. In contrast, the production of IL-6 and IL-8 in FLS upon stimulation was 3-fold and 1.6-fold higher, respectively, than in DF. Furthermore, induced IL-1β production in FLS, normalized relative to their, respectively, stimulated DF, was 2.5 times higher in non-RA versus RA-derived cells ( p = 0.032), an effect noted even after several passages of growth. Our data suggest that inductive expression of IL-1β in FLS is under specific inhibitory control. Increased production of IL-1β in FLS of susceptible individuals may lead to a higher risk of developing severe joint damage even in the absence of systemic inflammation.