Objective: Interleukin‐22 (IL‐22) is a novel cytokine of the IL‐10 family. Although its pathophysiologic function is largely unknown, induction of acute‐phase responses by IL‐22 has suggested proinflammatory properties. In this study, we sought to examine whether IL‐22 plays a role in the pathogenesis of rheumatoid arthritis (RA).Methods: Expression of IL‐22 and IL‐22 receptor 1 (IL‐22R1) was examined by reverse transcription–polymerase chain reaction (RT‐PCR), Western blot, and immunohistochemical analysis. The effects of recombinant IL‐22 (rIL‐22) on cultured synovial fibroblasts derived from RA patients (RASF), with regard to the proliferation of synovial fibroblasts and production of monocyte chemoattractant protein 1 (MCP‐1), were examined by alamer blue assay and enzyme‐linked immunosorbent assay, respectively.Results: IL‐22 messenger RNA was detected by RT‐PCR in RA synovial tissues and mononuclear cells isolated from RA synovial fluid samples. High levels of IL‐22 were expressed both in the lining and the sublining layers of RA synovial tissues. Staining for vimentin and CD68, as markers of synovial fibroblasts and macrophages, respectively, showed that the majority of IL‐22–positive cells were synovial fibroblasts and macrophages. IL‐22R1 was also expressed in both the lining and the sublining layers of RA synovial tissues. The majority of cells expressing IL‐22R1 were positive for vimentin, but not for CD68. Expression of IL‐22 and IL‐22R1 in RASF was confirmed by RT‐PCR and Western blot analysis. In vitro, rIL‐22 significantly increased proliferation of RASF and production of MCP‐1 by RASF above the value of medium controls. Moreover, MAPK activation was induced in RASF in response to IL‐22 stimulation.Conclusion: These data suggest that IL‐22, produced by synovial fibroblasts and macrophages, promotes inflammatory responses in RA synovial tissues by inducing the proliferation and chemokine production of synovial fibroblasts.

Objectives. To determine if the International Society of Nephrology/Renal Pathology Society (ISN/RPS) 2003 classification of lupus nephritis (LN) is helpful in predicting renal outcome. Methods. A total of 92 patients with LN who underwent renal biopsy in our hospital were re-classified according to the ISN/RPS 2003 criteria. Results. The mean patient age was 36.8 yrs and the median observation period was 65 months. The relative frequency for each class was as follows: Class I (minimal mesangial LN) 0%, Class II (mesangial proliferative LN) 13%, Class III (focal LN) 17%, Class IV (diffuse LN) 60% and Class V (membranous LN) 10%. Within Class IV, diffuse segmental (Class IV-S) was 25% and diffuse global (Class IV-G) 75%. During the observation period, renal function was more likely to deteriorate in Class IV-G cases than in Class IV-S cases. Importantly, when Class IV-G was subdivided into cases involving active lesion alone [IV-G (A)] or chronic lesion [IV-G (A/C)], the majority of cases in IV-G (A) was nephrotic, but responded well to therapy. In contrast, renal function declined only in IV-G (A/C) cases. Patients with Class IV-G (A/C) had persistent proteinuria in spite of intensified therapies. Moreover, the higher proportion of chronic lesions was related with the deterioration of renal function. Conclusions. This study showed that in Class IV-G cases, renal outcome differed in the presence of chronicity. Chronicity could be a critical factor in predicting outcome. Thus, the revised classification of LN is clinically valuable in identifying different renal outcomes among patients with diffuse LN.

Objective: To investigate the expression of activin A and its receptors in rheumatoid arthritis (RA) synovial tissues, and to determine the effect of activin A on cultured fibroblast‐like synoviocytes (FLS).Methods: The localization of activin A and activin type II receptor (ARII) in synovial tissues of RA patients was analyzed by immunohistochemistry. The expression of activin A and activin receptors in human cultured FLS was examined by reverse transcriptase–polymerase chain reaction and Western blotting. Enzyme‐linked immunosorbent assay was used to measure activin A in culture supernatants. The cell growth of FLS was determined by ³H‐thymidine incorporation and MTT assay.Results: Immunohistochemical analysis confirmed the up‐regulation of activin A in rheumatoid synovium as compared with osteoarthritis or normal joint tissues. CD68+ macrophage‐lineage cells and vimentin‐positive FLS were identified as activin‐producing cells in rheumatoid synovium. Both cell types also expressed ARII. The expression of activin A and ARII on cultured FLS was confirmed at the protein and messenger RNA levels. Interleukin‐1β (IL‐1β), tumor necrosis factor α, and transforming growth factor β activated FLS to secrete activin A. Recombinant activin A accelerated the proliferation of FLS, while follistatin, an endogenous activin antagonist, partially inhibited FLS proliferation induced by IL‐1β.Conclusion: These results suggest that activin A acts as a growth factor of FLS in RA.

Objective. IL-19 is a novel cytokine of the IL-10 family. In this study, we sought to examine whether IL-19 plays a role in the pathogenesis of RA. Methods. Expression of IL-19, IL-20 receptor 1 (IL-20R1) and IL-20R2 was examined by RT-PCR and immunohistochemical analysis in rheumatoid synovium. The effects of IL-19 on synovial cells established from rheumatoid synovium (RASCs), with regard to IL-6 production and signal transducers and activators of transcription3 (STAT3) activation, were examined by ELISA and western blot analysis, respectively. The effect of IL-19 on RASC apoptosis was examined by Hoechst staining, flow cytometry analysis of annexin V binding and caspase-3 activity. Results. IL-19, IL-20R1 and IL-20R2 mRNA were detected by RT-PCR in synovial tissues from RA patients. Immunohistochemical analysis showed IL-19 was predominantly expressed in the hyperplastic lining layers of RA synovial tissues. The majority of IL-19-positive cells were vimentin-positive and CD68-positive synovial cells, serving as markers of fibroblasts and macrophages, respectively. IL-20R1 and IL-20R2 (IL-20Rs) were expressed in both the lining and sublining layers of RA synovium. In RASC, IL-19 was induced by lipopolysaccharide stimulation and constitutive expression of IL-20Rs was observed, suggesting IL-19 has an autocrine action. In terms of this function, IL-19 induced STAT3 activation and increased IL-6 production by RASC above the medium control. Moreover, IL-19 significantly reduced RASC apoptosis induced by serum starvation. Conclusions. These data suggest that IL-19, produced by synovial cells, promotes joint inflammation in RA by inducing IL-6 production and decreasing synovial cell apoptosis.

Objective. To examine whether IL-6 promotes angiogenesis by modulating angiopoietin (Ang) expression in RA. Methods. Synovial fibroblasts derived from RA patients (RASFs) and human umbilical vein endothelial cells (HUVECs) were co-cultured for 6 days with or without recombinant IL-6, VEGF or Ang-1. HUVECs were stained with anti-CD31 antibody and their growth was determined by quantifying the CD31-positive area. SFs were collected from RA (n = 25) and OA (n = 7) patients. Results. In the co-culture system, IL-6 and VEGF significantly enhanced HUVEC growth to a similar extent. However, the morphology of proliferating cells was distinct between IL-6- and VEGF-stimulated HUVEC. HUVEC stimulated with IL-6 exhibited small, loose clusters surrounded by dispersed single cells, suggesting destabilized angiogenesis by IL-6. In the supernatants, IL-6 up-regulated VEGF compared with controls and Ang-2, while it down-regulated Ang-1. In contrast, down-regulation of Ang-1 was not observed with VEGF stimulation. Consistent with the destabilized morphology, stimulation with IL-6 decreased cell surface expression of vascular endothelial cadherin (VE-cadherin) on HUVEC, presumably by inducing internalization. Interestingly, adding recombinant Ang-1 partially inhibited IL-6-induced morphological changes in HUVEC including a destabilized morphology with small, loose clusters and internalization of VE-cadherin. In SFs from RA patients, VEGF was negatively correlated with Ang-1 (r = −0.559, P = 0.004). Conclusion. IL-6 not only enhances VEGF expression but also inhibits Ang-1 signalling by directly down-regulating Ang-1 expression and up-regulating Ang-2, an antagonist of Ang-1. These synergistic effects may play a critical role in destabilized angiogenesis in RA.

Sulfite, a common air pollutant, is toxic for humans, causing hypersensitivity or chronic airway diseases. We previously reported that sulfite is actively produced from neutrophils by stimulation with bacterial endotoxin, lipopolysaccharide (LPS). We also found that the serum sulfite concentration is increased in a rat model of sepsis induced by systemic injection of LPS. However, information on sulfite metabolism in human inflammatory conditions is limited. In the current study, the serum concentration of sulfite was determined in 25 patients with acute pneumonia. Serum sulfite concentration in pneumonia patients was significantly higher than that in control subjects (3.75 +/- 0.88 vs. 1.23 +/- 0.48 microM, respectively, P < 0.05). Among 20 patients, serum sulfite was serially determined before and after antibiotic therapy. The levels of serum sulfite were significantly reduced during the recovery phase compared with those during the acute phase (1.34 +/- 0.56 vs. 3.65 +/- 0.92 microM, respectively, P < 0.05). Moreover, neutrophils obtained from three patients during the acute phase of pneumonia spontaneously produced higher amounts of sulfite in vitro than those obtained after recovery. There was a close positive correlation (r = 0.71, P < 0.05) between serum sulfite and C-reactive protein (CRP) in patients with pneumonia. Taken together, the current findings suggest that serum sulfite increases during systemic inflammation in humans. Activated neutrophils might be responsible, at least in part, for the up-regulation of sulfite. Given various biological effects reported previously, sulfite may act as a mediator in inflammation.