Hongyue Wang

P2X7 Blockade Attenuates Murine Lupus Nephritis by Inhibiting Activation of the NLRP3/ASC/Caspase 1 Pathway

OBJECTIVE The NLRP3 inflammasome plays key roles in inflammation and autoimmunity, and purinergic receptor P2X7 has been proposed to be upstream of NLRP3 activation. The aim of the present study, using murine models, was to investigate whether the P2X7 /NLRP3 inflammasome pathway contributes to the pathogenesis of lupus nephritis (LN). METHODS MRL/lpr mice were treated with the selective P2X7 antagonist brilliant blue G (BBG) for 8 weeks. Following treatment, the severity of renal lesions, production of anti-double-stranded DNA (anti-dsDNA) antibodies, rate of survival, activation of the NLRP3/ASC/caspase 1 inflammasome pathway, and ratio of Th17 cells to Treg cells were evaluated. P2X7 -targeted small interfering RNA (siRNA) was also used for in vivo intervention. Similar evaluations were carried out in NZM2328 mice, a model of LN in which the disease was accelerated by administration of adenovirus-expressing interferon-α (AdIFNα). RESULTS Significant up-regulation of P2X7 /NLRP3 inflammasome signaling molecules was detected in the kidneys of MLR/lpr mice as compared with normal control mice. Blockade of P2X7 activation by BBG suppressed NLRP3/ASC/caspase 1 assembly and the subsequent release of interleukin-1β (IL-1β), resulting in a significant reduction in the severity of nephritis and circulating anti-dsDNA antibodies. The lifespan of the treated mice was significantly prolonged. BBG treatment reduced the serum levels of IL-1β and IL-17 and the Th17:Treg cell ratio. Similar results were obtained by specific siRNA silencing of P2X7 in vivo. The effectiveness of BBG treatment in modulating LN was confirmed in NZM2328 mice with AdIFNα-accelerated disease. CONCLUSION Activation of the P2X7 signaling pathway accelerates murine LN by activating the NLRP3/ASC/caspase 1 inflammasome, resulting in increased IL-1β production and enhanced Th17 cell polarization. Thus, targeting of the P2X7 /NLRP3 pathway should be considered as a novel therapeutic strategy in patients with lupus.

Bay11-7082 attenuates murine lupus nephritis via inhibiting NLRP3 inflammasome and NF-κB activation.

Nuclear factor-kappa B (NF-κB) and NLRP3 inflammasome are involved in inflammation and autoimmunity. In vitro data have shown that Bay11-7082 selectively inhibits NLRP3 inflammasome activity independent of NF-κB activity. In this study, we evaluated the therapeutic effects of Bay11-7082 on murine lupus nephritis (LN) in vivo. Twelve-week-old MRL/lpr mice were treated with either Bay11-7082 (5mg/kg) or vehicle (DMSO/PBS buffer) by intraperitoneal injection thrice per week for 8 weeks. NLRP3 inflammasome formation and NF-κB activation were measured. Histopathology, immune complex deposits, proteinuria, renal function and production of anti-dsDNA antibody as well as inflammatory markers were evaluated. Bay11-7082 treatment inhibited renal NLRP3 inflammasome formation and NF-κB activation in vivo. Bay11-7082 decreased proteinuria, blood urea nitrogen, resulting in dramatically attenuated renal damage. Bay11-7082-treated mice had decreased serum anti-dsDNA level and less renal immune complex deposition. The IL-1β, TNF-α and chemokine (C-C Motif) ligand 2 (CCL2) levels and infiltration of macrophages as well as the mortality were significantly reduced by Bay11-7082 treatment. This study suggests that dual inhibition of NLRP3 inflammasome and NF-κB activation using Bay11-7082 or its analogues may be a promising therapeutic strategy for preventing the progression of LN.

Myeloid-derived suppressor cells are proinflammatory and regulate collagen-induced arthritis through manipulating Th17 cell differentiation

Myeloid-derived suppressor cells (MDSC) and Th17 cells were found to expand in collagen-induced arthritis (CIA) significantly. Two subsets of MDSC, polymorphonuclear (PMN) and mononuclear (MO), were detected and their ratios varied during the development of CIA. The depletion of MDSC in vivo resulted in suppression of T-cell proliferation and decreased IL-17A and IL-1β production. The adoptive transfer of MDSC restored the severity of arthritis and Th17 cell differentiation. The depletion of MDSCs on day 35 resulted in arthritis amelioration without reaching a significant difference. Furthermore, MDSCs from CIA mice had higher production of IL-1β and promoted Th17 cell differentiation. The expansion of MDSCs in the peripheral blood of rheumatoid arthritis (RA) patients was in correlation with increased Th17 cells and disease activity DAS28. These results support the hypothesis that MDSC may play a significant proinflammatory role in the pathogenesis of CIA and RA by inducing Th17 development in an IL-1β-dependent manner.

Lupus Nephritis: Glycogen Synthase Kinase 3β Promotion of Renal Damage Through Activation of the NLRP3 Inflammasome in Lupus-Prone Mice

Glycogen synthase kinase 3β (GSK‐3β) has been demonstrated to be involved in immune and inflammatory responses via multiple signaling pathways, leading to the production of proinflammatory cytokines. The purpose of this study was to investigate the role of GSK‐3β in the pathogenesis of lupus nephritis in 2 mouse models.

Blockage of P2X7 attenuates acute lung injury in mice by inhibiting NLRP3 inflammasome.

Abstract NLRP3 inflammasome is engaged in the inflammatory response during acute lung injury (ALI). Purinergic receptor P2X7 has been reported to be upstream of NLRP3 activation. However, the therapeutic implication of P2X7 in ALI remains to be explored. The present study used lipopolysaccharide (LPS)-induced mouse model to investigate the therapeutic potential of P2X7 blockage in ALI. Our results showed that P2X7/NLRP3 inflammasome pathway was significantly upregulated in the lungs of ALI mice as compared with control mice. P2X7 antagonist A438079 suppressed NLRP3/ASC/caspase 1 activation, production of IL-1β, IL-17A and IFN-γ and neutrophil infiltration but not the production of IL-10, resulting in a significant amelioration of lung injury. Moreover, blockage of P2X7 significantly inhibited NLRP3 inflammasome activation and IL-1β production in bone marrow derived macrophages. Similar results were obtained using another P2X7 inhibitor brilliant blue G (BBG) in vivo. Thus, pharmacological blockage of P2X7/NLRP3 pathway can be considered as a potential therapeutic strategy in patients with ALI.

Myeloid-derived suppressor cells contribute to bone erosion in collagen-induced arthritis by differentiating to osteoclasts

Bone erosion is a sign of severe rheumatoid arthritis and osteoclasts play a major role in the bone resorption. Recently, myeloid-derived suppressor cells (MDSC) has been reported to be increased in collagen-induced arthritis (CIA). The number of circulating MDSCs is shown to correlate with rheumatoid arthritis. These findings suggest that MDSCs are precursor cells involved in bone erosion. In this study, MDSCs isolated from mice with CIA stimulated with M-CSF and RANKL in vitro expressed osteoclast markers and acquired osteoclast bone resorption function. MDSCs sorted from CIA mice were transferred into the tibia of normal DBA/1J mice and bones were subjected to histological and Micro CT analyses. The transferred CIA-MDSCs were shown to differentiate into TRAP(+) osteoclasts that were capable of bone resorption in vivo. MDSCs isolated from normal mice had more potent suppressor activity and much less capability to differentiate to osteoclast. Additional experiments showed that NF-κB inhibitor Bay 11-7082 or IκB inhibitor peptide blocked the differentiation of MDSCs to osteoclast and bone resorption. IL-1Ra also blocked this differentiation. In contrast, the addition of IL-1α further enhanced osteoclast differentiation and bone resorption. These results suggest that MDSCs are a source of osteoclast precursors and inflammatory cytokines such as IL-1, contributing significantly to erosive changes seen in rheumatoid arthritis and related disorders.

Anti-dsDNA antibodies induce inflammation via endoplasmic reticulum stress in human mesangial cells

BackgroundAnti-dsDNA antibodies play an important role in the pathogenesis of lupus nephritis (LN). Endoplasmic reticulum (ER) stress is a physical reaction under stressful condition and can cause inflammation when stimulation is sustained. This study investigated the roles of ER stress in anti-dsDNA antibody-induced inflammation response in human mesangial cells (HMCs).MethodAnti-dsDNA antibodies isolated from LN patients were used to stimulate HMCs. The expression of GRP78, PERK, p-PERK, p-eIF2α, ATF4, p-IRE1α, ATF6 and CHOP in HMCs was measured by western blot. NF-κB activation was detected by examining nuclear translocation of NF-κB p65. The expression and production of IL-1β, TNF-α and MCP-1 were examined by qPCR and ELISA.ResultsFlow cytometry and cellular ELISA showed that anti-dsDNA antibodies can bind to HMCs. The binding was not inhibited by blockage of Fc receptor. Anti-dsDNA antibody stimulation significantly enhanced the expression of GRP78, p-PERK, p-eIF2α and ATF4 in HMCs. However, no significant increase in the expression of p-IRE1α and ATF6 was found. In addition, anti-dsDNA antibodies also significantly increased the activation of NF-κB and upregulated the expression of IL-1β, TNF-α and MCP-1, which were suppressed by pretreatment of HMCs with chemical ER stress inhibitor 4-PBA. Transfection of specific ATF4 siRNA also significantly reduced the activation of NF-κB and expression of proinflammatory cytokines.ConclusionAnti-dsDNA antibodies induce NF-κB activation and inflammation in HMCs via PERK-eIF2α-ATF4 ER stress pathway.

Serum procalcitonin and C-reactive protein for differentiating bacterial infection from disease activity in patients with systemic lupus erythematosus

Abstract Objective. To study the clinical value of procalcitonin (PCT) and C-reactive protein (CRP) in differentiating bacterial infection from disease activity in systemic lupus erythematosus (SLE) patients. Method. PCT and CRP in active SLE patients complicated with and without bacterial infection were retrospectively studied. Bacterial infection was diagnosed by positive culture results or typical symptoms and signs combined with positive response to antibiotics. Disease activity of SLE was assessed by systemic lupus erythematosus disease activity index (SLEDAI). Result. One hundred and fourteen active SLE patients were recruited, 47 of which were with bacterial infection and 67 were non-infected. PCT and CRP levels were significantly elevated in patients with bacterial infection (P < 0.05). The ideal cutoff value for PCT was 0.38 ng/ml, at which the sensitivity (74.5%) and specificity (95.5%) combined the best. The negative predictive value and positive predictive value to detect bacterial infection were 84.2% and 92.1%, respectively. PCT but not the CRP level in the septic patients was significantly higher than that of non-septic ones. Meanwhile, in patients with SLEDAI score of > 10, both PCT and CRP levels were higher in patients with bacterial infection, but the difference was only statistically significant for PCT (P < 0.05). PCT was significantly reduced after anti-bacterial treatment. Conclusion. PCT test is superior to CRP test in detecting superimposed bacterial infection in active SLE patients. The levels of PCT are correlated with the severity of bacterial infection and can be used to monitor the response to antibiotic treatment.

Ac-SDKP ameliorates the progression of lupus nephritis in MRL/lpr mice.

N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is an endogenous tetrapeptide which can inhibit the differentiation, migration and activation of macrophages and suppress the proliferation of fibroblast. This study examined the effects of Ac-SDKP on the progression of lupus nephritis (LN). MRL/lpr mice received subcutaneous infusion of Ac-SDKP (1.0 mg kg(-1) d(-1)) or vehicle through implanted osmotic mini-pumps from 12 to 20 weeks until being euthanized. MRL/MpJ mice served as normal controls. The data indicative of renal inflammation and fibrosis were evaluated before and after treatment. Ac-SDKP-treated MRL/lpr mice showed reduced proteinuria and improved renal function compared with vehicle-treated controls. Ac-SDKP-treated mice demonstrated decreased inflammatory infiltrates of T cells and macrophages in the kidneys as compared to vehicle-treated animals. The treatment also inhibited the activation of NF-κB and production of TNF-α. Despite this, immune complex deposition and plasma anti-dsDNA levels were not statistically different between the two groups. In addition, the treatment inhibited renal expression of TGF-β1, α-SMA and fibronectin as well as the phosphorylation of Smad2/3. Ac-SDKP treatment ameliorated LN through exerting anti-inflammatory and anti-fibrotic effects on MRL/lpr mice, providing therapeutic potential for halting the progression of LN.

CARD11 blockade suppresses murine collagen-induced arthritis via inhibiting CARD11/Bcl10 assembly and T helper type 17 response

The scaffold protein caspase recruitment domain‐containing protein 11 (CARD11) is implicated in the regulation of inflammation and autoimmunity. The present study aimed to explore the role of CARD11 in the pathogenesis of rheumatoid arthritis (RA). Mice with collagen‐induced arthritis (CIA) were treated with either CARD11‐targeted interfering RNA (CARD11 siRNA) or control siRNA by intraperitoneal injection every 3 days after CIA establishment. The clinical score of arthritis was recorded every other day. Synovial inflammation and cartilage erosion were evaluated by histology and microcomputed tomography (micro‐CT). Serum anti‐type II collagen (anti‐CII) antibodies and cytokines were measured by enzyme‐linked immunosorbent assay (ELISA). The CARD11/Bcl10 formation and nuclear factor‐kappa B (NF‐κB) activation was assessed by immunoprecipitation and immunoblotting, and the percentage of T helper type 17 (Th17) cells was determined by flow cytometry. Systemic administration of CARD11 siRNA significantly reduced the clinical score of CIA severity. As indicated by the histology, joint inflammation and destruction were attenuated by CARD11 siRNA treatment. Micro‐CT demonstrated less severe joint destruction in CARD11 siRNA‐treated mice than in control mice. CARD11 siRNA treatment resulted in inhibition of CARD11/Bcl10 formation and the subsequent NF‐κB activation. In addition, treatment with CARD11 siRNA resulted in a pronounced decrease in proinflammatory cytokines interleukin (IL)‐1β, IL‐6 and IL‐17. Serum anti‐CII antibody and the percentage of Th17 cells were also significantly reduced. CARD11 is involved in the pathogenesis of CIA by formation of the CARD11/Bcl10 complex and enhancement of the Th17 cell response. Targeting CARD11 provides a novel research direction in the development of therapeutic strategies for RA.