Mesangial cells of lupus-prone mice are sensitive to chemokine production

Cordyceps protein alleviates renal injury by inhibiting T cell infiltration and Th1 cell differentiation in lupus nephritis mice

BACKGROUND

T cell infiltration and differentiation play a central part in the development of lupus nephritis (LN). Our prior research has indicated that protein, the primary active component of cordyceps (WCP), a traditional Chinese medicine, possesses properties that can enhance renal fibrosis and provide kidney protection. Nonetheless, the connection between WCP and T cell infiltration and differentiation in LN remains poorly understood.

OBJECTIVE

The objective of this research was to assess the immunomodulatory impacts of WCP in LN mice and elucidate the underlying mechanism through in vivo and in vitro investigations.

METHODS

To investigate the impact and mechanism of WCP in MRL/lpr lupus-prone mice, WCP (1.5 g/kg/d), Bailing capsules (BC, 0.75 g/kg/d), and saline in equivalent quantities were administered to the mice over a period of 8 weeks. The therapeutic effects, T cell infiltration and differentiation of WCP on MRL/lpr mice were verified through ELISA, Hematoxylin-eosin (H&E), Periodic Acid Schiff (PAS) staining, immunofluorescence, Luminex analysis and flow cytometry. The mechanism by which WCP alleviates LN was investigated using tissues of mice, T cells and Mouse Podocyte Clone-5 (MPC-5) cells by transcriptomics, Western blot (WB), and Real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

We found that WCP improved LN in MRL/lpr mice by reducing urinary protein, creatinine, and serum auto antibodies, increasing complement 3 (C3) level, improving renal immunopathology and downregulating serum cytokines, including IFN-γ, IL-12, and RANTES. Notably, the infiltration of CD4+ and CD8+ T cells in the kidney was reduced by WCP. Similarly, the cell transwell co-culturation study showed that the WCP treated MPC-5 cells were weaker in inducing T cell migration. Consistent with this finding, our observations revealed that WCP could inhibit T cell-related chemokine expression in kidney and MPC-5 cells, as well as reduce the levels of TLR4, MYD88, phosphorylated-p38, phosphorylated-ERK, and phosphorylated-JNK. On the other hand, WCP was found to greatly inhibit the Th1 cells differentiation in vivo and in vitro. Cytokine-receptor induced Th1 cell differentiation pathway and PI3K-AKT pathway were the most enriched pathways based on differentially expressed genes (DEGs) enrichment analysis among different cell groups. Results from RT-qPCR and WB showed that WCP notably reduced the levels of IL-12, p-STAT4, IFN-γ, p-STAT1, p-PI3K, and p-AKT in T cells.

CONCLUSION

WCP demonstrated positive immunomodulatory effects on LN disease, by decreasing the T cells infiltration through TLR4/MYD88/MAPK signaling pathway and inhibiting Th1 cells differentiation via IL-12-STAT4 and IFN-γ-STAT1 pathways, in addition to the PI3K-AKT pathway.

Sirtuin 3 is required for the dexmedetomidine-mediated alleviation of inflammation and oxidative stress in nephritis

INTRODUCTION

Although sirtuin 3 (SIRT3) is known to be involved in dexmedetomidine (DEX)-mediated alleviation of renal ischemia and reperfusion injury, the influence of the association between DEX and SIRT3 on nephritis development remains unclear. In this study, the role of SIRT3 in DEX-mediated amelioration of inflammation and oxidative stress in nephritis as well as the possible underlying mechanism were explored in vivo and in vitro.

METHODS

An animal model of glomerulonephritis was generated by injecting mice with interferon-alpha (IFNα)-expressing adenoviruses, and periodic acid-Schiff staining was then used to reveal pathogenicity-related changes in the renal tissue. Additionally, human embryonic kidney cells (HEK293) and renal mesangial cells (RMCs) were treated with IFNα to establish cell models of inflammation in vitro.

RESULTS

DEX administration alleviated glomerulonephritis in the animal model and upregulated SIRT3 expression in the renal tissue. SIRT3 knockdown inhibited the renoprotective effects of DEX against nephritis. IFNα induced inflammation, oxidative stress, and apoptosis in the RMCs and HEK293 cells and reduced their growth, as evidenced by the evaluation of cytokine levels (enzyme-linked immunosorbent assay), reactive oxygen species generation, catalase and superoxide dismutase activities, nuclear factor-erythroid factor 2-related factor 2/heme oxygenase-1 signal transduction, apoptotic cell proportion, and cell viability. In addition to promoting SIRT3 expression, DEX inhibited IFNα-induced inflammation, oxidative stress, and apoptosis in these cells and promoted their viability. SIRT3 knockdown partially reversed the beneficial effects of DEX on RMCs and HEK293 cells.

CONCLUSIONS

Our results suggest that DEX exhibits renoprotective activity during nephritis progression, protecting renal cells against inflammatory injury by promoting SIRT3 expression.

Downregulation of Renal Hsa-miR-127-3p Contributes to the Overactivation of Type I Interferon Signaling Pathway in the Kidney of Lupus Nephritis

MicroRNAs are involved in the pathogenesis of systemic lupus erythematosus (SLE) and dysregulated in the kidneys of lupus nephritis (LN) patients, but their pathogenic roles in LN are largely unknown. Janus Kinase 1 (JAK1) mediates the activation of the downstream signaling pathways of many inflammatory cytokines, including type I interferon (IFN-I) signaling pathway which is critical to the development of SLE and LN. Thus, JAK1 is a potent therapeutic target for these autoimmune diseases. However, there are few studies demonstrating the dysregulation of JAK1 in autoimmune diseases and the molecular mechanism behind it. In this concise report, we show an inhibitory effect of hsa-miR-127-3p, a microRNA that is downregulated in the renal tissues of LN patients, on IFN-I signaling. We found the overexpression of hsa-miR-127-3p could inhibit the induction of ISRE and GAS mediated gene expression, the phosphorylation of STAT1 and STAT2, and the upregulation of IFN stimulated genes (ISGs) stimulated by IFN-I. While, hsa-miR-127-3p antagonist enhanced the activation of IFN-I signaling in primary renal mesangial cells. Subsequently, we identified JAK1 as a bona fide target gene of hsa-miR-127-3p and showed hsa-miR-127-3p targeted JAK1 through binding to its 3’UTR and coding region. Consistently, we found the downregulation of hsa-miR-127-3p was associated with the upregulation of JAK1 and ISGs in kidney tissues of LN patients. Our data indicate renal downregulation of hsa-miR-127-3p contributes to the overactivation of IFN-I signaling pathway in the kidneys of LN patients through promoting the expression of JAK1, suggesting hsa-miR-127-3p mimics may be used to inhibit JAK1 and IFN-I signaling pathway in LN.

Circular RNA-0007059 protects cell viability and reduces inflammation in a nephritis cell model by inhibiting microRNA-1278/SHP-1/STAT3 signaling

Background

Increasing evidence has indicated that circular RNAs (circRNAs) play a role in various diseases. However, the influence of circRNAs in nephritis remains unknown.

Methods

Microarray analysis and RT-qPCR were used to detect the expression of circRNA. Type I IFN were administrated to RMC and HEK293 cells to establish a nephritis cell model. CCK-8, MTT assay, and flow cytometry were used to assess cell proliferation, viability, and apoptosis of cells. Bioinformatics analysis and dual luciferase reporter assay detect the interaction of circ_0007059, miRNA-1278, and SHP-1. Glomerulonephritis was performed in a mouse model by administration of IFNα-expressing adenovirus. IHC staining showed the pathogenic changes.

Results

In the present study, the expression of circ_0007059 in type I interferon (IFN)-treated renal mesangial cells (RMCs), lupus nephritis (LN) specimens, and HEK293 cells was downregulated compared with that in normal healthy samples and untreated cells. Circ_0007059 overexpression resulted in increased cell proliferation, cell viability, apoptosis, and inflammation-associated factors (CXCL10, IFIT1, ISG15, and MX1) in RMCs and HEK293 cells. In addition, circ_0007059 overexpression significantly restored cell proliferation and viability and inhibited IFN-induced apoptosis. Further, the increased expression resulted in reduced inflammation and the downregulation of CXCL10, IFIT1, ISG15, and MX1 in RMCs and HEK293 cells. Circ_0007059 serves as a sponge for miR-1278 so that the latter can target the 3′-untranslated region of SHP-1. Overexpressed circ_0007059 inhibited miR-1278 expression and elevated SHP-1 expression, subsequently reducing STAT3 phosphorylation. Meanwhile, miR-1278 was upregulated and SHP-1 was downregulated in LN samples and IFN-treated cells. The restoration of miR-1278 counteracted the effect of circ_0007059 on viability, apoptosis, and inflammation as well as on SHP-1/STAT3 signaling in RMCs and HEK293 cells. We also investigated the role of SHP-1 overexpression in IFN-treated RMCs and HEK293 cells; SHP-1 overexpression resulted in a similar phenotype as that observed with circ_0007059 expression.

Conclusions

The study indicates that circ_0007059 protects RMCs against apoptosis and inflammation during nephritis by attenuating miR-1278/SHP-1/STAT3 signaling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00372-6.

Quercetin reduces TNF-α-induced mesangial cell proliferation and inhibits PTX3 production: Involvement of NF-κB signaling pathway

Lupus nephritis (LN) is an autoimmune disease caused by systemic lupus erythematosus. Excessive proliferation of mesangial cells is one of the most serious pathological manifestations of LN. In addition, the expression of PTX3 is elevated in the serum of patients with LN. Quercetin has good anti-inflammatory effects and immunomodulatory activities. In this study, the result of MTT indicated that quercetin treatment alleviated the excessive proliferation of mesangial cells. ELISA and immunofluorescence experiments showed that quercetin treatment inhibited the expression of PTX3. Three doses of quercetin (20, 40, and 80 μM) were selected for the experiment. It is noteworthy that the efficacy of quercetin at 80 μM was significantly better than that of other dose groups. And the effect in inhibiting PTX3 expression was comparable with that of the PDTC (80 μM) positive control. Western blot and qRT-PCR analysis revealed that quercetin treatment reduced the expression of nuclear factor-κB p65 and IKKβ, increased the expression of IκBα, and inhibited the expression of PTX3. In conclusion, through inhibiting the activation of nuclear factor-κB signaling pathway, quercetin treatment could reduce the expression of PTX3 and inhibit the excessive proliferation of mesangial cells, suggesting that quercetin is a potential therapeutic drug for LN.

Toll-like receptors in lupus nephritis

The pathogenesis of systemic autoimmune diseases such as systemic lupus erythematosus (SLE) is based on the loss of self-tolerance against ubiquitous autoantigens involving all mechanisms of adaptive immunity. However, data accumulating over the last decade imply an important role also for numerous elements of innate immunity, namely the Toll-like receptors in the pathogenesis of SLE. Here we discuss their role in the most common organ complication of SLE, i.e. lupus nephritis. We summarize experimental and clinical data on the expression and functional contribution of the Toll-like receptors in immune complex glomerulonephritis, and intrarenal inflammation. Based on these discoveries Toll-like receptors are evolving as therapeutic targets for the treatment of SLE and lupus nephritis.

New insights into the role of renal resident cells in the pathogenesis of lupus nephritis

Systemic lupus erythematosus (SLE), an autoimmune disease of unknown etiology, is characterized by the production of autoantibodies and end-organ damage. Lupus nephritis affects up to 70% of patients with SLE and is the most critical predictor of morbidity and mortality. The immunopathogenesis of SLE is complex and most clinical trials of biologics targeting immune cells or their mediators have failed to show efficacy in SLE patients. It has therefore become increasingly clear that additional, local factors give rise to the inflammation and organ damage. In this review, we describe recent advances in the role of renal resident cells, including podocytes, mesangial cells, and epithelial cells, in the pathogenesis of lupus nephritis.

NLRP3 inflammasome: Pathogenic role and potential therapeutic target for IgA nephropathy

We have previously showed that IL-1β is involved in the pathogenesis of both spontaneously occurring and passively induced IgA nephropathy (IgAN) models. However, the exact causal-relationship between NLRP3 inflammasome and the pathogenesis of IgAN remains unknown. In the present study, we showed that [1] IgA immune complexes (ICs) activated NLRP3 inflammasome in macrophages involving disruption of mitochondrial integrity and induction of mitochondrial ROS, bone marrow-derived dendritic cells (BMDCs) and renal intrinsic cells; [2] knockout of NLRP3 inhibited IgA ICs-mediated activation of BMDCs and T cells; and [3] knockout of NLRP3 or a kidney-targeting delivery of shRNA of NLRP3 improved renal function and renal injury in a mouse IgAN model. These results strongly suggest that NLRP3 inflammasome serves as a key player in the pathogenesis of IgAN partly through activation of T cells and mitochondrial ROS production and that a local, kidney-targeting suppression of NLRP3 be a therapeutic strategy for IgAN.

SPAK plays a pathogenic role in IgA nephropathy through the activation of NF-κB/MAPKs signaling pathway

Sterile 20/SPS1-related proline/alanine-rich kinase (SPAK) can stimulate production of proinflammatory cytokines and interact with inflammation-related molecules. However, it has yet to be determined whether SPAK plays a pathophysiological role in the complicated pathological mechanisms of IgA nephropathy (IgAN), which is mainly characterized by mesangial cell (MC) proliferation and is the most common form of glomerulonephritis. In the present study, we examined the pathophysiological role of SPAK in IgAN using a mouse model and cell models. Our results clearly showed that (1) SPAK deficiency prevents the development of IgAN and inhibits production of immune/inflammatory mediators and T cell activation and proliferation; and (2) when primed with IgA immune complexes (IgA IC), both peritoneal macrophages and primary MCs from SPAK knockout mice show markedly reduced production of proinflammatory cytokines and inhibition of NF-κB/MAPKs activation. We proposed that activation of SPAK and the NF-κB/MAPKs signaling pathway in MCs, macrophages and T cells of the glomerulus may be a mechanism underlying the pathogenesis of IgAN. The activation of SPAK in renal tubuloepithelial cells either directly by IgA IC or an indirect action of the activated MCs or infiltrating mononuclear leukocytes seen in the kidney may further aggravate the disease process of IgAN. Our results suggest that SPAK is a potential therapeutic target for the glomerular disorder.

Neutrophils, Dendritic Cells, Toll-Like Receptors, and Interferon-α in Lupus Nephritis

Finding better treatments for lupus nephritis requires an understanding of the pathogenesis of the causative systemic disease, how this leads to kidney disease, and how lupus nephritis progresses to end-stage kidney disease. Here, we provide a brief conceptual overview on the related pathomechanisms. As a main focus we discuss in detail the roles of neutrophils, dendritic cells, Toll-like receptors, and interferon-α in the pathogenesis of lupus nephritis by separately reviewing their roles in extrarenal systemic autoimmunity and in intrarenal inflammation and immunopathology.

Hyperoside ameliorates glomerulosclerosis in diabetic nephropathy by downregulating miR-21

The purpose of this study was to investigate the therapeutic effects of hyperoside (Hyp) on glomerulosclerosis in diabetic nephropathy and its underlying mechanisms. Blood glucose, kidney mass, and renal function of mice were measured. Renal morphology was observed using hematoxylin and eosin, periodic acid - Schiff's, and Masson's trichrome stain. Fibronectin (FN) and collagen IV (COL IV) in kidney were determined by Western blot and immunohistochemical studies. Matrix metalloproteinases (MMP)-2 and -9 and tissue inhibitors of metalloproteinase (TIMP)-1 in renal tissues were detected on both the mRNA and protein levels. miRNA expression and artificial alterations by miRNA agomir transfection were evaluated to investigate the protective mechanism of Hyp in mesangial cells. Hyp effectively improved renal function and physiologic features of db/db mice. Hyp also ameliorated glomerulosclerosis by suppressing FN, COL IV, and TIMP-1 expressions and promoting MMP-9 and MMP-2 expressions. The change in MMP-9 mRNA expression was inconsistent with that in protein levels in kidney, indicating that there was a post-transcriptional regulation. Further exploration in vitro showed that miR-21 was downregulated by Hyp, increasing expression of its target, MMP-9. These results suggest that Hyp can ameliorate glomerulosclerosis in diabetic nephropathy by downregulating miR-21 to increase expression of its target, MMP-9.

Toll-like receptor activation in the pathogenesis of lupus nephritis

The pathogenesis of systemic lupus erythematosus (SLE) and lupus nephritis is complex but no longer enigmatic. Much progress has been made to on the polygenetic origin of lupus in identifying gene variants that permit the loss of tolerance against nuclear autoantigens. Along the same line in about 50% of lupus patients additional genetic weaknesses promote immune complex glomerulonephritis and filtration barrier dysfunction. Here we briefly summarize the pathogenesis of SLE with a focus on loss of tolerance and the role of toll-like receptors in the "pseudo"-antiviral immunity concept of systemic lupus. In addition, we discuss the local role of Toll-like receptors in intrarenal inflammation and kidney remodeling.

Chemokines and Chemokine Receptors in the Development of Lupus Nephritis

Lupus nephritis (LN) is a major cause of morbidity and mortality in the patients with systemic lupus erythematosus (SLE), an autoimmune disease with damage to multiple organs. Leukocyte recruitment into the inflamed kidney is a critical step to promote LN progression, and the chemokine/chemokine receptor system is necessary for leukocyte recruitment. In this review, we summarize recent studies on the roles of chemokines and chemokine receptors in the development of LN and discuss the potential and hurdles of developing novel, chemokine-based drugs to treat LN.

A low toxicity synthetic cinnamaldehyde derivative ameliorates renal inflammation in mice by inhibiting NLRP3 inflammasome and its related signaling pathways

Uncontrolled inflammation is a leading cause of various chronic diseases. Cinnamaldehyde (CA) is a major bioactive compound isolated from the essential oil of the leaves of Cinnamomum osmophloeum kaneh that exhibits anti-inflammatory activity; however, the use of CA is limited by its cytotoxicity. Here, we synthesized three CA derivatives and identified 4-hydroxycinnamaldehyde-galactosamine (HCAG) as a low toxicity anti-inflammatory compound in vitro (HCAG IC50 ≫ 1600 µM; CA IC50=40 µM) and in vivo. HCAG reduced pro-inflammatory mediator expression in LPS-activated macrophages by inhibiting MAPK and PKC-α/δ phosphorylation, decreasing ROS generation and reducing NF-κB activation. HCAG also reduced NLRP3 inflammasome-derived IL-1β secretion by inhibiting the ATP-mediated phosphorylation of AKT and PKC-α/δ. In a mouse model of LPS-induced renal inflammation, we observed reduced albuminuria and a mild degree of glomerular proliferation, glomerular sclerosis and periglomerular inflammation in the HCAG-treated mice compared with the vehicle-treated mice. The underlying mechanisms for these renoprotective effects involved: (1) inhibited NLRP3 inflammasome activation; (2) decreased superoxide anion levels and apoptosis; and (3) suppressed activation of NF-κB and related downstream inflammatory mediators.

Genetics and pathogenesis of systemic lupus erythematosus and lupus nephritis

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder that has a broad spectrum of effects on the majority of organs, including the kidneys. Approximately 40-70% of patients with SLE will develop lupus nephritis. Renal assault during SLE is initiated by genes that breach immune tolerance and promote autoantibody production. These genes might act in concert with other genetic factors that augment innate immune signalling and IFN-I production, which in turn can generate an influx of effector leucocytes, inflammatory mediators and autoantibodies into end organs, such as the kidneys. The presence of cognate antigens in the glomerular matrix, together with intrinsic molecular abnormalities in resident renal cells, might further accentuate disease progression. This Review discusses the genetic insights and molecular mechanisms for key pathogenic contributors in SLE and lupus nephritis. We have categorized the genes identified in human studies of SLE into one of four pathogenic events that lead to lupus nephritis. We selected these categories on the basis of the cell types in which these genes are expressed, and the emerging paradigms of SLE pathogenesis arising from murine models. Deciphering the molecular basis of SLE and/or lupus nephritis in each patient will help physicians to tailor specific therapies.

Qufeng Tongluo Prescription () inhibits mesangial cell proliferation and promotes apoptosis through regulating cell cycle progression

OBJECTIVE

To study the effects and possible underlying mechanism of Qufeng Tongluo Prescription (, QFTL) on the regulation of mesangial cells (MCs) proliferation and apoptosis.

METHODS

The MCs used in this experiment have undergone five passages induced by lipopolysaccharide (LPS). Changes in the proliferation, apoptosis, cell cycle regulatory proteins and mRNA expression levels of the MCs after administration of Benazepril or QFTL were measured by methyl thiazolyl tetrazolium (MTT) reduction assay, flow cytometry, Western blot and quantitative real-time polymerase chain reaction (qRT-PCR), respectively.

RESULTS

The addition of Benazepril or QFTL serum inhibited LPS-induced MC proliferation after treatment for 24, 48 and 72 h, respectively (P<0.05 or P<0.01). Moreover, the inhibitory effect is more significant in the QFTL group at 48 h (P<0.05). Compared with the control group, LPS-induced cell proliferation decreased the number of cells in G1 phase versus cells in S and G2/M phases, while the addition of QFTL and Benazepril serum increased the ratio of cells at G1 phase (P<0.05 or P<0.01) to cells at S phase (P<0.01), implicating the cell cycle inhibition effect exerted by QFTL. LPS decreased the level of MC apoptosis, compared with the control group (P<0.05), while QFTL and Benazepril serum increased the level of MC apoptosis (P<0.01). Moreover, the difference between the QFTL group and the Benazepril group was statistically significant (P<0.01). Compared with the control group, the protein and mRNA expression levels of cylinD1, cyclin dependent kinase 2 (CDK2) and p21 were significantly increased (P<0.05 or P<0.01), p27 was decreased but with no statistical significance (P>0.05); After being treated with QFTL and Benazepril serum, the protein and mRNA expression levels of cylinD1, CDK2, p21 were decreased and p27 increased significantly (P<0.05 or P<0.01); Compared with the Benazepril group, QFTL show better effects on protein and mRNA expression levels of cylinD1, CDK2 (P<0.05 or P<0.01) and p21 protein expression (P<0.05).

CONCLUSION

QFTL inhibits MCs proliferation, promotes MCs apoptosis through an underlying mechanism of down-regulating the protein and mRNA expression levels of cylinD1, CDK2, p21 and up-regulation of the expression level of p27.

MicroRNAs implicated in the immunopathogenesis of lupus nephritis

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the deposition of immune complexes due to widespread loss of immune tolerance to nuclear self-antigens. Deposition in the renal glomeruli results in the development of lupus nephritis (LN), the leading cause of morbidity and mortality in SLE. In addition to the well-recognized genetic susceptibility to SLE, disease pathogenesis is influenced by epigenetic regulators such as microRNAs (miRNAs). miRNAs are small, noncoding RNAs that bind to the 3′ untranslated region of target mRNAs resulting in posttranscriptional gene modulation. miRNAs play an important and dynamic role in the activation of innate immune cells and are critical in regulating the adaptive immune response. Immune stimulation and the resulting cytokine milieu alter miRNA expression while miRNAs themselves modify cellular responses to stimulation. Here we examine dysregulated miRNAs implicated in LN pathogenesis from human SLE patients and murine lupus models. The effects of LN-associated miRNAs in the kidney, peripheral blood mononuclear cells, macrophages, mesangial cells, dendritic cells, and splenocytes are discussed. As the role of miRNAs in immunopathogenesis becomes delineated, it is likely that specific miRNAs may serve as targets for therapeutic intervention in the treatment of LN and other pathologies.

Estrogen receptor-alpha mediates Toll-like receptor-2 agonist-induced monocyte chemoattractant protein-1 production in mesangial cells

TLR2 agonists are well known for inducing NF-kB activation and inflammation, while estrogen receptor-alpha (ER-α) is a regulator of estrogen-mediated anti-inflammatory responses. In the present work, we determined the role of ER-α and phosphorylated ER-α in TLR2 agonist-induced MCP1 production in mesangial cells. We found that TLR2 agonists induced nuclear localization of phospho-ER-α (serine 118), and estrogen and TLR2 agonists both induced phosphorylation of ER-α at the serine 118 and 104/106 positions. Incubation of MRL/lpr mesangial cells with estrogen was found to attenuate TLR2 agonist-mediated MCP1 production. To determine the mode of action of ER-α/pER-α (serine-118), we used the ER-α inhibitor MPP and transfected mesangial cells with ER-α siRNA. ER-α inhibition was found to decrease MCP1 production in mesangial cells. Thus, ER-α/pER-α is an intermediate regulator for both TLR2-mediated MCP1 production during inflammation and estrogen-mediated anti-inflammatory signals in mesangial cells.

Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) mediates p38 mitogen-activated protein kinase activation and signal transduction in peripheral blood mononuclear cells from patients with lupus nephritis

Forty-two patients with systemic lupus erythematosus (SLE), including 26 patients with renal damage and 16 without, and 20 healthy controls were included in the study. The isolated peripheral blood mononuclear cells (PBMCs) were treated with a p38 inhibitor (SB203580) or anti-tumor necrosis factor-like weak inducer of apoptosis (TWEAK) mAb, with or without phytohemagglutinin/phorbol myristate acetate (PHA/PMA) stimulation. Western blot experiments were used to evaluate the protein expression of TWEAK and p38 MAPK in PBMCs .Next, the contents of interleukin-10 (IL-10) and monocyte chemoattractant protein-1 (MCP-1) in the supernatant were measured by ELISA. The results showed that expression of TWEAK protein in PBMCs from lupus nephritis patients was significantly higher than that from SLE patients without renal damage and healthy controls. PHA/PMA simulation could upregulate the productions of TWEAK and p-p38MAPK in PBMCs from patients with SLE. Anti-TWEAK mAb treatment downregulated both TWEAK and p-p38 MAPK expression in PBMCs, as well as IL-10 and MCP-1 in the supernatant; SB203580 had the same effect on cytokine production in PBMC, but had no effect on the expression of TWEAK. Our results suggested that TWEAK-p38 MAPK-IL-10, MCP-1 signaling pathway in PBMC played an important pathogenic role in lupus nephritis.

Heat shock protein 90 inhibition by 17-DMAG lessens disease in the MRL/lpr mouse model of systemic lupus erythematosus

Elevated expression of heat shock protein 90 (HSP90) has been found in kidneys and serum of systemic lupus erythematosus (SLE) patients and MRL/Mp-Fas(lpr)/Fas(lpr) (MRL/lpr) autoimmune mice. We investigated if inhibition of HSP90 would reduce disease in MRL/lpr mice. In vitro, pretreatment of mesangial cells with HSP90 inhibitor Geldanamycin prior to immune-stimulation showed reduced expression of IL-6, IL-12 and NO. In vivo, we found HSP90 expression was elevated in MRL/lpr kidneys when compared to C57BL/6 mice and MRL/lpr mice treated with HSP90 inhibitor 17-DMAG. MRL/lpr mice treated with 17-DMAG showed decreased proteinuria and reduced serum anti-dsDNA antibody production. Glomerulonephritis and glomerular IgG and C3 were not significantly affected by administration of 17-DMAG in MRL/lpr. 17-DMAG increased CD8(+) T cells, reduced double-negative T cells, decreased the CD4/CD8 ratio and reduced follicular B cells. These studies suggest that HSP90 may play a role in regulating T-cell differentiation and activation and that HSP90 inhibition may reduce inflammation in lupus.

Lupus nephritis: current update

Lupus nephritis is a major cause of morbidity and mortality in patients with systemic lupus erythematosus. The general consensus is that 60% of lupus patients will develop clinically relevant nephritis at some time in the course of their illness. Prompt recognition and treatment of renal disease is important, as early response to therapy is correlated with better outcome. The present review summarizes our current understanding of the pathogenic mechanisms underlying lupus nephritis and how the disease is currently diagnosed and treated.

Toll-like receptor 4 signaling is involved in IgA-stimulated mesangial cell activation

PURPOSE

Deposition of polymeric IgA1 in the kidney mesangium is the hallmark of IgA nephropathy, but the molecular mechanisms of IgA-mediated mesangial responses and inflammatory injuries remain poorly understood. We hypothesize that Toll-like receptor 4 (TLR4) is involved in IgA-induced mesangial cell activation.

MATERIALS AND METHODS

Mouse mesangial cells were stimulated with lipopolysaccharide (LPS) (1 μg/mL), IgA (20 μg/mL), or both, and TLR4 expression was measured by real time RT-PCR and Western blot. Intracellular responses to LPS or IgA were assessed by Western blot for ERK1/2, JNK, p38 MAP kinases (MAPKs), Iκ-Bα degradation and fibronectin secretion. MCP-1 secretion was assessed by ELISA. Small interfering RNA (siRNA) of TLR4 was used to confirm that the effects were caused by TLR4 activity.

RESULTS

LPS- or IgA-treatment upregulated the levels of TLR4 mRNA and protein in cultured MMC at 24 h. LPS and IgA induced rapid phosphorylation of MAPKs, but degradation of Iκ-Bα was observed only in LPS-treated MMC. LPS, but not IgA, induced increased secretion of MCP-1 and fibronectin at 24 h or 48 h. Combined LPS and IgA treatment did not cause additional increases in TLR4 mRNA and protein levels or Iκ-Bα degradation, and MCP-1 and fibronectin secretions were less than with LPS alone. LPS- or IgA-induced TLR4 protein levels and MAPK activation were inhibited by transfection with TLR4 siRNA.

CONCLUSION

These results indicate that the activation of MAPKs and MCP-1 secretion are mediated by TLR4, at least in part, in IgA-treated mesangial cells. TLR4 is involved in mesangial cell injury by induction of pro-inflammatory cytokines in IgA nephropathy.

Toll-like receptor 4 signaling is involved in IgA-stimulated mesangial cell activation

PURPOSE

Deposition of polymeric IgA1 in the kidney mesangium is the hallmark of IgA nephropathy, but the molecular mechanisms of IgA-mediated mesangial responses and inflammatory injuries remain poorly understood. We hypothesize that Toll-like receptor 4 (TLR4) is involved in IgA-induced mesangial cell activation.

MATERIALS AND METHODS

Mouse mesangial cells were stimulated with lipopolysaccharide (LPS) (1 μg/mL), IgA (20 μg/mL), or both, and TLR4 expression was measured by real time RT-PCR and Western blot. Intracellular responses to LPS or IgA were assessed by Western blot for ERK1/2, JNK, p38 MAP kinases (MAPKs), Iκ-Bα degradation and fibronectin secretion. MCP-1 secretion was assessed by ELISA. Small interfering RNA (siRNA) of TLR4 was used to confirm that the effects were caused by TLR4 activity.

RESULTS

LPS- or IgA-treatment upregulated the levels of TLR4 mRNA and protein in cultured MMC at 24 h. LPS and IgA induced rapid phosphorylation of MAPKs, but degradation of Iκ-Bα was observed only in LPS-treated MMC. LPS, but not IgA, induced increased secretion of MCP-1 and fibronectin at 24 h or 48 h. Combined LPS and IgA treatment did not cause additional increases in TLR4 mRNA and protein levels or Iκ-Bα degradation, and MCP-1 and fibronectin secretions were less than with LPS alone. LPS- or IgA-induced TLR4 protein levels and MAPK activation were inhibited by transfection with TLR4 siRNA.

CONCLUSION

These results indicate that the activation of MAPKs and MCP-1 secretion are mediated by TLR4, at least in part, in IgA-treated mesangial cells. TLR4 is involved in mesangial cell injury by induction of pro-inflammatory cytokines in IgA nephropathy.

Interferon-lambda1 induces peripheral blood mononuclear cell-derived chemokines secretion in patients with systemic lupus erythematosus: its correlation with disease activity

INTRODUCTION

Systemic lupus erythematosus (SLE) is an autoimmune disease involving multiple organ systems. Previous studies have suggested that interferon-lambda 1 (IFN-λ1), a type III interferon, plays an immunomodulatory role. In this study we investigated its role in SLE, including its correlation with disease activity, organ disorder and production of chemokines.

METHODS

We determined levels of IFN-λ1 mRNA in peripheral blood mononuclear cells (PBMC) and serum protein levels in patients with SLE using real-time polymerase chain reaction (real-time PCR) and enzyme-linked immunoassay (ELISA). Further, we detected the concentration of IFN-inducible protein-10 (IP-10), monokine induced by IFN-γ (MIG) and interleukin-8 (IL-8) secreted by PBMC under the stimulation of IFN-λ1 using ELISA.

RESULTS

IFN-λ1 mRNA and serum protein levels were higher in patients with SLE compared with healthy controls. Patients with active disease showed higher IFN-λ1 mRNA and serum protein levels compared with those with inactive disease as well. Serum IFN-λ1 levels were positively correlated with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), anti-dsDNA antibody, C-reactive protein (CRP) and negatively correlated with complement 3. Serum IFN-λ1 levels were higher in SLE patients with renal involvement and arthritis compared with patients without the above-mentioned manifestations. IFN-λ1 with different concentrations displayed different effects on the secretion of the chemokines IP-10, MIG and IL-8.

CONCLUSIONS

These findings indicate that IFN-λ1 is probably involved in the renal disorder and arthritis progression of SLE and associated with disease activity. Moreover, it probably plays an important role in the pathogenesis of SLE by stimulating secretion of the chemokines IP-10, MIG and IL-8. Thus, IFN-λ1 may provide a novel research target for the pathogenesis and therapy of SLE.

Therapeutic potential of DCB-SLE1, an extract of a mixture of Chinese medicinal herbs, for severe lupus nephritis

The pathogenesis of lupus nephritis is mainly attributable to a complex interaction between the innate and adaptive immune systems, including T and B cell function abnormalities. In addition to autoantibody production and immune complex deposition, Th1 and Th17 cytokines may play key roles in the development and progression of lupus nephritis. Acute onset of severe lupus nephritis remains a challenge in terms of prevention and treatment. In the present study, we evaluated the therapeutic effects of DCB-SLE1, an extract of a mixture of four traditional Chinese medicinal herbs (Atractylodis macrocephalae Rhizoma, Eucommiae cortex, Lonicerae caulis, and Hedyotidis diffusae Herba), on an accelerated severe lupus nephritis model, characterized by acute onset of proteinuria, azotemia, autoantibody production, and development of severe nephritis, induced by twice weekly injection of New Zealand black/white F1 mice with Salmonella-type lipopolysaccharide. DCB-SLE1 was administered daily by gavage starting 2 days after the first dose of induction of lipopolysaccharide, and the mice were euthanized at week 1 or week 5. The results showed that DCB-SLE1 significantly ameliorated the hematuria, proteinuria, renal dysfunction, and severe renal lesions by 1) suppression of B cell activation and decreased autoantibody production; 2) negative regulation of T cell activation/proliferation and natural killer cell activity; 3) suppression of IL-18, IL-6, and IL-17 production and blocking of NF-κB activation in the kidney; and 4) prevention of lymphoid and renal apoptosis. These results show that DCB-SLE1 can protect the kidney from autoimmune response-mediated acute and severe damage through systemic immune modulation and anti-inflammation pathways.

Innate immune receptors and autophagy: implications for autoimmune kidney injury

Inflammation is the immune system's response to infectious or noninfectious sources of danger. Danger recognition is facilitated by various innate immune receptor families including the Toll-like receptors (TLRs), which detect danger signals in extracellular and intracellular compartments. It is an evolving concept that renal damage triggers intrarenal inflammation by immune recognition of molecules that are being released by dying cells. Such danger-associated molecules act as immunostimulatory agonists to TLRs and other innate immune receptors and induce cytokine and chemokine secretion, leukocyte recruitment, and tissue remodeling. As a new entry to this concept, autophagy allows stressed cells to reduce intracellular microorganisms, protein aggregates, and cellular organelles by moving and subsequently digesting them in autophagolysosomes. Within the autophagolysosome, endogenous molecules and danger-associated molecules may be presented to TLRs or loaded onto the major histocompatibility complex and presented as autoantigens. Here we discuss the current evidence for the danger signaling concept in autoimmune kidney injury and propose that autophagy-related processing of self-proteins provides a source of immunostimulatory molecules and autoantigens. A better understanding of danger signaling should enable us to unravel yet unknown triggers for renal immunopathology and progressive kidney disease.

Peptide corresponding to the C terminus of tissue factor pathway inhibitor inhibits mesangial cell proliferation and activation in vivo

Mesangial cells (MsCs) are one of the resident cell types in the glomerulus and are important with respect to its function and structure. The activation and proliferation of MsCs occur in several types of glomerulonephritis, particularly proliferative glomerulonephritis, producing a series of protein factors and matrix components that impair the normal structure and function of the glomerulus. To inhibit proliferation or induction of apoptosis is considered to be one mechanism that can be used to treat these diseases. In previous studies, we found that the tissue factor pathway inhibitor (TFPI) induces the apoptosis of cultured rat MsCs. Here, we expressed a series of TFPI fragments as fusion proteins to maltose binding protein (MBP-TFPI(162-188), MBP-TFPI(187-241), MBP-TFPI(240-276), MBP-TFPI(162-241), MBP-TFPI(187-276) and MBP-TFPI(162-276)) and applied them to cultured rat mesangial cells. The C terminus of TFPI, a peptide corresponding to residues 240-276 of TFPI, was confirmed to induce apoptosis of MsCs in vitro. To observe the effect of this peptide on MsCs in vivo, we performed intramuscular gene transfer treatment on a rat model of proliferative glomerulonephritis with a plasmid containing the gene for the C terminus of TFPI. This revealed that the C terminus of TFPI exhibited suppressive effects on the activation and proliferation of MsCs and, thereby, improved renal function. Our data indicate that the C terminus of TFPI could be used in the treatment of proliferative glomerulonephritis.

Infections and autoimmunity--friends or foes?

Autoimmunity can be triggered by many environmental factors, among which infectious agents are pivotal. Here, we summarize current knowledge of the relationship between infection and autoimmunity. An autoimmune disease can be induced or triggered by infectious agents, which can also determine its clinical manifestations. Most infectious agents, such as viruses, bacteria and parasites, can induce autoimmunity via different mechanisms. In many cases, it is not a single infection but rather the 'burden of infections' from childhood that is responsible for the induction of autoimmunity. The development of an autoimmune disease after infection tends to occur in genetically susceptible individuals. By contrast, some infections can protect individuals from specific autoimmune diseases (i.e. the hygiene hypothesis).

Pathogenic anti-DNA antibodies modulate gene expression in mesangial cells: involvement of HMGB1 in anti-DNA antibody-induced renal injury

Although anti-DNA antibodies have been decisively linked to the pathogenesis of lupus nephritis, the mechanisms have not been conclusively determined. Recently, we reported that anti-DNA antibodies may contribute to kidney damage by upregulation of proinflammatory genes in mesangial cells (MC), a process involving both Fc receptor-dependent and independent pathways. In investigating the mechanism by which pathogenic anti-DNA antibodies modulate gene expression in MC, we found that the pathogenic anti-DNA antibody 1A3F bound to high mobility group binding protein 1 (HMGB1), an endogenous ligand for TLR2/4 and RAGE (receptor for advanced glycation end products). Interestingly, HMGB1 treatment of MC induced a similar pattern of genes as stimulation with 1A3F. Furthermore, HMGB1 and 1A3F exhibited a synergistic proinflammatory effect in the kidney, where increased expression of HMGB1 was found in lupus patients but not in patients with other types of renal disease. TLR2/Fc and RAGE/Fc inhibited the proinflammatory effects of 1A3F on MC. Finally, we found enhanced susceptibility of lupus prone MRL-lpr/lpr (MRL/lpr) as compared to normal BALB/c derived MC to pathogenic anti-DNA antibody and LPS stimulation (in particular enhanced chemokine synthesis), in addition to significantly increased expression of TLR4. Our results suggest that gene upregulation in MC induced by nephritogenic anti-DNA antibodies is TLR2/4 and RAGE-dependent. Finally, HMGB1 may act as a proinflammatory mediator in antibody-induced kidney damage in systemic lupus erythematosus (SLE).

A novel transcript of mouse interleukin-20 receptor acts on glomerular mesangial cells as an aggravating factor in lupus nephritis

We identified a novel soluble protein, mouse (m)IL-20R1a, generated by alternative splicing of the mIL-20R1 gene, which encodes one subunit of the receptor complex for mIL-19, mIL-20 and mIL-24. mIL-20R1a has 77.14% amino-acid identity with the extracellular domain of mIL-20R1. However, no significant interaction between mIL-20R1a and mIL-19 or mIL-20 was detected. Consequently, we aimed to clarify whether mIL-20R1a might function as a novel effector on certain cells. Competitive binding assays demonstrated that mIL-20R1a bound to cell surfaces and resulted in AKT and JNK phosphorylation in primary mesangial cells (MCs) isolated from either the wild-type mice, DBA/W mice, or the SLE-prone mice, NZB/W mice. NZB/W MCs expressed more mIL-20R1a transcript than DBA/W MCs did. Furthermore, mIL-20R1a-treated NZB/W MCs produced higher level of chemokines, renal fibrogenic factors and ROS than mIL-20R1a-treated DBA/W MCs did. These factors are involved in the pathogenesis of lupus nephritis. Endogenous mIL-20R1a was upregulated in the bladder, colon and spleen tissue of NZB/W mice. Elevated mIL-20R1a in the spleen tissue of NZB/W mice was expressed mainly in monocytes and B cells. mIL-20R1a further induced mIL-10 production by the anti-IgM antibody-stimulated B cells in NZB/W mice. Therefore, mIL-20R1a-mediated effects may exacerbate the disease outcome of lupus nephritis.