Xiaoxia Zhu

Activation of Sirt1 by Resveratrol Inhibits TNF-α Induced Inflammation in Fibroblasts

Inflammation is one of main mechanisms of autoimmune disorders and a common feature of most diseases. Appropriate suppression of inflammation is a key resolution to treat the diseases. Sirtuin1 (Sirt1) has been shown to play a role in regulation of inflammation. Resveratrol, a potent Sirt1 activator, has anti-inflammation property. However, the detailed mechanism is not fully understood. In this study, we investigated the anti-inflammation role of Sirt1 in NIH/3T3 fibroblast cell line. Upregulation of matrix metalloproteinases 9 (MMP-9), interleukin-1beta (IL-1β), IL-6 and inducible nitric oxide synthase (iNOS) were induced by tumor necrosis factor alpha (TNF-α) in 3T3 cells and resveratrol suppressed overexpression of these pro-inflammatory molecules in a dose-dependent manner. Knockdown of Sirt1 by RNA interference caused 3T3 cells susceptible to TNF-α stimulation and diminished anti-inflammatory effect of resveratrol. We also explored potential anti-inflammatory mechanisms of resveratrol. Resveratrol reduced NF-κB subunit RelA/p65 acetylation, which is notably Sirt1 dependent. Resveratrol also attenuated phosphorylation of mammalian target of rapamycin (mTOR) and S6 ribosomal protein (S6RP) while ameliorating inflammation. Our data demonstrate that resveratrol inhibits TNF-α-induced inflammation via Sirt1. It suggests that Sirt1 is an efficient target for regulation of inflammation. This study provides insight on treatment of inflammation-related diseases.

Adipokines in Psoriatic Arthritis Patients: The Correlations with Osteoclast Precursors and Bone Erosions

Significant bone remodeling with disordered osteoclastogenesis has been implicated in the pathogenesis of psoriatic arthritis (PsA). And there is a high prevalence of the metabolic syndrome (MS) in PsA patients. Adipokines, especially leptin and adiponectin, have recently been reported to be involved in the development and regulation of some autoimmune diseases. In this study, we examined the alternation of circulating osteoclastogenesis related cytokines [tumor necrosis factor-α (TNF-α), osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL)] and adipokines (leptin, adiponectin, resistin, chemerin, omentin) in PsA patients, and analysed the correlations between these factors and osteoclast precursors numbers, radiographic damage scores, and disease activity index. 41 PsA patients, 20 psoriasis patients, and 24 healthy controls were recruited. Blood samples were obtained for detecting the levels of TNF-α, OPG, RANKL and the adipokines. The numbers of osteoclast precursors (OCs) in peripheral blood were assessed. Radiographs of affected joints in PsA patients were scored for erosion, joint-space narrowing, osteolysis, and new bone formation. Compared with healthy controls, patients with PsA had higher TNF-α, RANKL, OCs, leptin and omentin but lower adiponectin and chemerin. Increased serum levels of TNF-α, RANKL, leptin, and omentin were positively correlated with OCs numbers. In contrast, serum adiponectin levels were decreased in PsA patients and negatively correlated with OCs numbers. TNF-α, RANKL and leptin were positively correlated with Psoriatic Arthritis Joint Activity Index (PsAJAI). Only TNF-α was positively correlated with radiographic damage scores. Our data demonstrated that systemic expression of soluble mediators of osteoclastogenesis and adipokines were disordered in PsA. Certain adipokines were elevated in the circulation of patients with PsA and might contribute to pathogenesis of arthritis. Prospective studies will be of interest to determine the pluripotent effects of adipokines on osteoclastogenesis in chronic inflammatory rheumatic diseases. Future studies may lead to novel therapeutic strategies.

T Follicular Helper Cells Mediate Expansion of Regulatory B Cells via IL-21 in Lupus-Prone MRL/lpr Mice

T follicular helper (Tfh) cells can mediate humoral immune responses and augment autoimmunity, whereas the role of Tfh cells on regulatory B (B10) cells in autoimmunity diseases is not clear. Here, we investigated the percentages of Tfh cells and B10 cells in lupus-prone MRL/Mp-lpr/lpr (MRL/lpr) mice and examined the effects and mechanism of Tfh cell-derived interleukin-21 (IL-21) on IL-10 production during the differentiation of B10 cells. Both Tfh cells and B10 cells were expanded in spleens of MRL/lpr mice. In addition, a positive correlation between the proportions of Tfh cells and B10 cells was observed. Tfh cell-derived IL-21 from MRL/lpr mice could promote IL-10 production during the differentiation of B10 cells. Importantly, neutralization of IL-21 inhibited IL-10 production and expansion of B10 cells both in vitro and in vivo. IL-21 induced IL-10 production via activation of phosphorylated signal transduction and activator of transcription 3 (p-STAT3). Inhibition of p-STAT3 effectively blocked IL-10 production during the differentiation of B10 cells. Moreover, IL-21-induced IL-10 exerted a regulatory function by inhibiting the proliferation of T cells. These data suggest that Tfh cells not only mediate humoral immune responses and augment autoimmunity but also play a broader role in immune regulatory actions via the induction of IL-10 production.

S100A9 promotes human lung fibroblast cells activation through receptor for advanced glycation end‐product‐mediated extracellular‐regulated kinase 1/2, mitogen‐activated protein‐kinase and nuclear factor‐κB‐dependent pathways

S100A9 belongs to the S100 family of calcium‐binding proteins and plays a key role in many inflammatory conditions. Recent studies have found that S100A9 was elevated significantly in the bronchoalveolar lavage fluid of idiopathic pulmonary fibrosis patients, and might be a biomarker for fibrotic interstitial lung diseases. However, the exact function of S100A9 in pulmonary fibrosis needs further studies. We performed this study to investigate the effect of S100A9 on human embryo lung fibroblast (HLF) proliferation and production of cytokines and collagen, providing new insights into the possible mechanism. S100A9 promoted proliferation of fibroblasts and up‐regulated expression of both proinflammatory cytokines interleukin (IL)‐6, IL‐8, IL‐1β and collagen type III. S100A9 also induced HLF cells to produce α‐smooth muscle actin (α‐SMA) and receptor for advanced glycation end‐product (RAGE). In addition, S100A9 caused a significant increase in extracellular‐regulated kinase (ERK)1/2 mitogen‐activated protein kinase (MAPK) phosphorylation, while the status of p38 and c‐Jun N‐terminal kinase (JNK) phosphorylation remained unchanged. Treatment of cells with S100A9 also enhanced nuclear factor kappa B (NF‐κB) activation. RAGE blocking antibody pretreatment inhibited the S100A9‐induced cell proliferation, cytokine production and pathway phosphorylation. S100A9‐mediated cell activation was suppressed significantly by ERK1/2 MAPK inhibitor and NF‐κB inhibitor. In conclusion, S100A9 promoted HLF cell growth and induced cells to secret proinflammatory cytokines and collagen through RAGE signalling and activation of ERK1/2 MAPK and NF‐κB pathways.

Interleukin-22 Inhibits Bleomycin-Induced Pulmonary Fibrosis

Pulmonary fibrosis is a progressive and fatal fibrotic disease of the lungs with unclear etiology. Recent insight has suggested that early injury/inflammation of alveolar epithelial cells could lead to dysregulation of tissue repair driven by multiple cytokines. Although dysregulation of interleukin- (IL-) 22 is involved in various pulmonary pathophysiological processes, the role of IL-22 in fibrotic lung diseases is still unclear and needs to be further addressed. Here we investigated the effect of IL-22 on alveolar epithelial cells in the bleomycin- (BLM-) induced pulmonary fibrosis. BLM-treated mice showed significantly decreased level of IL-22 in the lung. IL-22 produced γ δT cells were also decreased significantly both in the tissues of lungs and spleens. Administration of recombinant human IL-22 to alveolar epithelial cell line A549 cells ameliorated epithelial to mesenchymal transition (EMT) and partially reversed the impaired cell viability induced by BLM. Furthermore, blockage of IL-22 deteriorated pulmonary fibrosis, with elevated EMT marker (α-smooth muscle actin (α-SMA)) and overactivated Smad2. Our results indicate that IL-22 may play a protective role in the development of BLM-induced pulmonary fibrosis and may suggest IL-22 as a novel immunotherapy tool in treating pulmonary fibrosis.

Increased expression of S100A8 and S100A9 in patients with diffuse cutaneous systemic sclerosis. A correlation with organ involvement and immunological abnormalities

S100A8 and S100A9 play important roles in immune and inflammatory disorders. The role of the two proteins in systemic sclerosis (SSc) remains unknown. Fifty-seven diffuse cutaneous SSc (dcSSc) patients, 31 limited cutaneous SSc (lcSSc) patients were recruited in the present study. The expression of S100A8 and S100A9 in plasma was measured using an enzyme-linked immunosorbent assay and the mRNA levels in peripheral blood were assessed using reverse transcriptase quantitative PCR. The expression and distribution of S100A8, S100A9, and receptor for advanced glycation end products (RAGE), in skin tissues was analyzed by immunohistochemistry. The plasma concentrations of S100A8 and S100A9 were significantly higher in dcSSc patients than in normal controls and lcSSc patients. Both S100A8 and S100A9 levels were significantly increased in dcSSc patients with lung or kidney involvement. Increased plasma levels of S100A8 and S100A9 in dcSSc patients were associated with several autoantibodies. Transcription levels of S100A8 and S100A9 in peripheral blood were found elevated in both dcSSc and lcSSc patients than normal controls. Immunohistochemistry demonstrated higher S100A8 and S100A9 expression in sclerotic skin than in normal skin. The number of S100A8, S100A9, or RAGE positive fibroblasts was also significantly increased. Highly elevated expression of both S100A8 and S100A9 was found in dcSSc patients. There was close correlation with disease severity and serological abnormalities, suggesting that the two proteins may play important roles in the development of systemic sclerosis.

New Interleukins in Psoriasis and Psoriatic Arthritis Patients: The Possible Roles of Interleukin-33 to Interleukin-38 in Disease Activities and Bone Erosions

Objectives: New interleukins (ILs), especially members of IL-1 and IL-12 families, have recently been reported to be involved in the development and regulation of autoimmune and inflammatory diseases. In this study, we aimed to explore the impact of these new ILs in psoriasis (Ps) and psoriatic arthritis (PsA). Methods: Forty PsA patients, 20 Ps patients, and 20 healthy controls (HCs) were recruited. Blood samples were obtained for detecting the levels of ILs, IL-12/23p40, and tumor necrosis factor α (TNF-α). The severity of skin lesions was assessed by the Psoriasis Area and Severity Index (PASI). Arthritis activities of PsA patients were assessed by the PsA Joint Activity Index. For PsA patients, circulating osteoclastogenesis-related cytokines (osteoprotegerin and receptor activator of nuclear factor-κB ligand) and numbers of osteoclast precursors were evaluated. Radiographic features of affected joints in these patients were scored for erosion, joint-space narrowing, osteolysis, and new bone formation. Correlations among levels of these ILs, Ps, and PsA disease activities and bone erosions were studied. Results: Ps and PsA patients had higher serum levels of TNF-α, IL-12/23p40, and IL-33. Serum levels of IL-34 and IL-35 were higher in PsA patients than in Ps patients and HCs. Patients with pustular Ps had higher serum levels of IL-36α and IL-38 than patients with Ps vulgaris or HCs. Increased serum levels of IL-36α were positively correlated with PASI. Conclusion: Certain ILs were elevated in the circulation of patients with Ps and PsA, which might contribute to the pathogenesis of skin lesions and arthritis.

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.

Vertical inhibition of PI3K/Akt/mTOR signaling demonstrates in vitro and in vivo anti-fibrotic activity

BACKGROUND The mammalian target of rapamycin (mTOR) regulates cellular activity in many diseases, but the complex interplay with PI3K/Akt pathway may hampers its function. OBJECTIVE This study was undertaken to determine the activity of PI3K/Akt/mTOR signaling in the fibroblasts from systemic sclerosis (SSc) patients, and compare the effects of vertical inhibiting PI3K/Akt/mTOR by BEZ235 and inhibiting mTOR alone by rapamycin in fibroblast activation and in two complementary established mouse model of SSc. METHODS Pharmaceutical specific inhibitors BEZ235 and rapamycin were used to vertical inhibit PI3K/Akt/mTOR signaling and mTOR signaling alone in cultured fibroblasts and in mice. SSc mouse model was established by daily injecting bleomycin subcutaneously or by overexpression of constitutively active type I TGF-β receptor (TβRI(ca)). To delineate the mechanisms underlying the antifibrotic effects of BEZ235 and rapamycin, activity of PI3K/Akt/mTOR signaling was analyzed by determining the expressions of phosphorylated Akt, GSK-3β, mTOR and S6 ribosomal protein (S6). RESULTS Primary dermal fibroblasts demonstrated hyperactivity of PI3K/Akt and mTOR signaling. mTOR inhibitor rapamycin failed to inhibit dermal fibrosis in an established SSc mouse model. However, administration of a dual inhibitor for PI3K/Akt and mTOR signaling BEZ235 attenuated dermal fibrosis by reversing increased dermal thickness and collagen deposition in two SSc mouse models. Furthermore, BEZ235 showed superior inhibitory effect on fibroblast activation relative to rapamycin in vitro. Also both BEZ235 and rapamycin could prevent the phosphorylation of mTOR and S6 completely. BEZ235 also blocked the activation of Akt and GSK-3β dramatically, whereas rapamycin has been shown to increase further upregulation of phosphorylated Akt on Ser473 both in vitro and in vivo. CONCLUSION These data show that blocking PI3K/Akt/mTOR with BEZ235 leads to superior inhibitory effect for dermal fibrosis, suggesting that vertical inhibition of PI3K/Akt/mTOR signaling may have therapeutic potential for SSc.

The effect of resveratrol on the recurrent attacks of gouty arthritis.

Gouty arthritis is characterized by inflammation induced by monosodium urate (MSU) crystal deposition, which is resulted by an increase of serum urate concentration. The management of gout, especially the recurrent acute attacks of chronic gouty arthritis, is still a problem to be resolved. In this study, we aimed to develop the preventive and therapeutic effect of resveratrol on gouty arthritis. MSU was used to induce gouty arthritis in the foot pad of C57BL/6 mice. Yeast polysaccharide and potassium oxonate were used to induce hyperuricemia in Kunming mice. Resveratrol was intraperitoneal injected to the mice in the treatment group. The pad inflammation and the level of serum uric acid were investigated to estimate the effect of resveratrol in gouty arthritis. Hyperuricemia was significantly detected in the mice treated with yeast polysaccharide and potassium oxonate, and gouty arthritis was successfully induced with MSU in mice. We further identified that resveratrol inhibited pad swelling and pad 99mTc uptake in gouty mice. Moreover, serum uric acid level was also decreased by resveratrol in hyperuricemia mice. This study highlighted that resveratrol might be applied to prevent the recurrent acute attack of gouty arthritis because of its inhibition of articular inflammation and down-regulation of serum uric acid.