Pristane-induced Lupus Nephritis Research Articles

Fibroblast growth factor 21 mitigates lupus nephritis progression via the FGF21/Irgm 1/NLRP3 inflammasome pathway

As an endocrine cytokine, fibroblast growth factor 21 (FGF21) exhibits anti-inflammatory properties. With the development of lupus nephritis (LN), which is tightly related to pathogenic factors, including inflammation and immune cell dysregulation, we explored the impact of Fibroblast Growth Factor 21 (FGF21) as well as its underlying mechanism. We induced an in vivo LN model using pristane in both wild-type C57BL/6 and FGF21 knockout (FGF21–/–) mice. LN serum obtained from 32-week-old wild-type LN mice was used to stimulate RAW264.7 and human renal tubular epithelial (HK-2) cells to mimic an in vitro LN model. Moreover, our findings revealed that FGF21–/– mice showed more severe kidney injury compared to wild-type mice, as evidenced by increased levels of renal function markers, inflammatory factors, and fibrosis markers. Notably, exogenous administration of FGF21 to wild-type LN mice markedly mitigated these adverse effects. Additionally, we used tandem mass tag (TMT)-based quantitative proteomics to detect differentially expressed proteins following FGF21 treatment. Results indicated that 121 differentially expressed proteins influenced by FGF21 were involved in biological processes such as immune response and complement activation. Significantly upregulated protein Irgm 1, coupled with modulated inflammatory response, appeared to contribute to the beneficial effects of FGF21. Furthermore, Western blot analysis demonstrated that FGF21 upregulated Irgm 1 while inhibiting nucleotide-binding oligomerization domain-like receptors family pyrin domain including 3 (NLRP3) inflammasome expression. Silencing Irgm 1, in turn, reversed FGF21′s inhibitory effect on NLRP3 inflammasome. In summary, FGF21 can potentially alleviate pristane-induced lupus nephritis in mice, possibly through the FGF21/Irgm 1/NLRP3 inflammasome pathway.

Anti-complement factor H (CFH) autoantibodies could delay pristane-induced lupus nephritis

PurposeAnti-complement factor H (CFH) autoantibodies could be detected in lupus and its significance remained to be elucidated. Herein, we aimed to explore the roles of anti-CFH autoantibodies based on pristane-induced lupus mice.MethodsTwenty-four female Balb/c mice were randomly divided into four groups, with one group injected with pristane (pristane group), one group with pristane and then human CFH (hCFH) (pristane-CFH group) 3 times, and the other two as vertical controls, PBS group and PBS-CFH group. Histopathological analysis was performed six months after pristane administration. Levels of hCFH, anti-CFH autoantibodies and anti-dsDNA antibody were detected. Murine IgG (mIgG) were purified and cross-reactivity, epitopes, subclasses and functional analysis were further evaluated in vitro.ResultsImmunization with hCFH and subsequent development of anti-CFH autoantibodies significantly attenuated nephritis of pristane-induced lupus, including lower levels of urinary protein and serum creatinine, decreased levels of serum anti-dsDNA antibody, greatly ameliorated renal histopathologic damage, decreased IgG, complements (C1q, C3) deposits and lower inflammatory factor (IL-6) expression in glomerulus. Furthermore, the purified mIgG (contained anti-CFH autoantibodies) could recognize both hCFH and murine CFH, and the epitopes were predominantly located in hCFH short consensus repeats (SCRs) 1–4, 7 and 11–14. The IgG subclasses were predominant IgG1. The autoantibodies could enhance the binding between hCFH and C3b, and increase factor I mediated-C3b lysis in vitro.ConclusionOur results suggested that anti-CFH autoantibodies could attenuate pristane-induced lupus nephritis by increasing bio-functions of CFH on regulating complement activation and controlling inflammation.

The Effect of Snail Mucus (Achatina Fulica) Toward The Activity and Chronicity Indices of Renal Histology in Pristane-Induced Lupus Nephritis Mice Model

Background: Snail mucus (Achatina Fulica) has been known to contain heparan sulfate, and acharan sulfate, a glycosaminoglycan with anti-inflammatory properties and might repair the injured glomeruli. Aim: This study aims to find the effect of snail mucus on activity and chronicity indices of renal histology in a pristane-induced lupus nephritis mice model. Method: This was an experimental study with a post-test-only control group design using 42 mice strains Balb/C. Mice were randomized into six groups: control, lupus nephritis, methylprednisolone, snail mucus 0.5 ccs, snail mucus 0,5 cc and methylprednisolone, and snail mucus one cc and methylprednisolone group. Result: Snail mucus significantly affected the activity index (p = 0.001). The lowest activity index was shown by snail mucus one cc and methylprednisolone group. While the chronicity index was not significantly affected by the snail mucus with p = 0.195. Snail mucus decreases the activity index of renal histology in the pristane-induced lupus nephritis mice model but not the chronicity index. Bangladesh Journal of Medical Science Vol. 22 No. 03 July’23 Page : 515-520

#3635 THERAPEUTIC STRATEGIES TARGETING RAGE IMPROVES RENAL OUTCOME IN LUPUS NEPHRITIS

Abstract Background and Aims Lupus nephritis (LN) occurs in up to 60% of patients with systemic lupus erythematosus (SLE). Despite of current development of immunosuppressant agents, LN still impairs the survival and quality of life in SLE patients. Receptor for advanced glycation endproducts (RAGE) is a multi-ligand receptor that belongs to the immunoglobulin superfamily, which is strongly associated with innate immune system. In the present study, we examined whether RAGE is involved in the development of LN. Further, we explored the therapeutic impact of DNA-aptamer directed against RAGE on lupus-related kidney injury. Method [Protocol 1] RAGE expression in kidneys and urinary RAGE excretion (uRAGE) were determined at 8, 12, 16, 18, 20-week-old by real-time PCR and ELISA, respectively in MRL/lpr, SLE-prone mice. [Protocol 2] LN was induced by peritoneally injecting pristane in wild type and RAGE globally knockout mice. [Protocol 3] MRL/lpr mice were subcutaneously administrated with DNA-aptamer raised against RAGE (RAGE-apt) or Control-aptamer (Ctrl-apt) for 10weeks. Results [Protocol 1] uRAGE, but not urinary protein excretion, was increased in 8-week-old MRL/lpr mice when compared to that of the control of MRL/MPJ mice. uRAGE is positively correlated with urinary NAG, a tubular injury marker, suggesting that uRAGE can predict the onset and the progression of LN. Immunofluorescence staining demonstrated that RAGE was upregulated in distal tubules but not in glomerulus in early stage, meanwhile RAGE started to be extensively expressed in nephron at late stage of LN. Not only tubules, but RAGE was also found in infiltrated macrophages in glomerulus. In proximal tubules (PTC), RAGE was co-localized with cathepsine D, a lysosomal aspartyl protease, and Rab7, a marker of late endocytosis, suggesting that PTC RAGE is involved in endosome-related protein degradation. [Protocol 2] Pristane-induced the increase in systolic blood pressure was reduced with improvement of renal dysfunction in RAGE knockouts. RAGE knockouts also showed less fibrosis with the decrease in macrophage infiltration when compared to wild type mice in pristane-induced lupus nephritis. [Protocol 3] Similar to RAGE knockouts, administration of RAGE-apt reduced systolic blood pressure and attenuated the renal dysfunction. RAGE-apt also ameliorated mesangial expansion, crescent formation, and macrophage infiltration into glomerulus in MRL/lpr mice. The level of pro-inflammatory cytokines gene expression including IL-6, TNF-a, and MCP-1 was reduced by RAGE-apt, but not Ctrl-apt, in MRL/lpr mice. Conclusion RAGE could be involved in the pathogenesis of LN, and RAGE-DNA aptamer might be one of the promising therapeutic strategies for preventing the development of LN.

Effects of Hyperbaric Oxygen on Anti-dsDNA Antibodies and IL-6 in BALB/c Mice with Pristane-Induced Lupus Nephritis

Effects of Hyperbaric Oxygen on Anti-dsDNA Antibodies and IL-6 in BALB/c Mice with Pristane-Induced Lupus Nephritis

Hyperbaric Oxygen Ameliorates The Expression of Tumor Growth Factor-β and Malondialdehyde in Pristane-induced Lupus Nephritis Mice Model

BACKGROUND: Lupus nephritis (LN) is associated with chronic renal failure and a high mortality rate. Tumor growth factor-β (TGF-β) plays a basic part in keeping up immune homeostasis, meanwhile extensive oxidation of the lipid membrane in LN causes the arrangement of malondialdehyde (MDA). Up to date, the mechanism of hyperbaric oxygen (HBO) therapy in LN has not been elucidated well. Hence this study was conducted to assess the impact of HBO therapy on TGF-β and MDA expression in the pristane-induced LN mice model.METHODS: Thirty-two mice aged 8-12 old weeks were isolated into 4 groups: normal saline-injected mice (group 1); pristane-injected mice (group 2); as well as pristane-injected followed by HBO-exposured with 2.4 (group 3) and 1.5 (group 4) atmosphere absolute (ATA) pressure. Pristane were injected intraperitoneal to initiate LN. Two months after pristane injection, the mice were placed within 24 hours in the special cage for metabolic examination to determined that pristane-induced LN mice model was successfully formed and marked by the occurring proteinuria. Oxidative stress was assessed by examining MDA, while systemic inflammation was assessed by examining by TGF-β. MDA and TGF-β serum were measured by enzyme-linked immunosorbent assay (ELISA).RESULTS: A significantly lower (p<0.050) MDA expression was found in group 3 in comparison with group 2. The results also showed that TGF-β level was significantly increased (p<0.050) in group 3 compared to group 2.CONCLUSION: HBO therapy ameliorates inflammation in LN by diminishing MDA and expanding TGF-β levels through activating antioxidants.KEYWORDS: lupus nephritis, hyperbaric oxygen, malondialdehyde, tumor growth factor-β

PS-B08-8: THERAPEUTIC STRATEGIES TARGETING RAGE IMPROVES RENAL OUTCOME IN LUPUS NEPHRITIS

Introduction: Lupus nephritis (LN) is present in 60% of patients with systemic lupus erythematosus (SLE). Despite of current development of immunosuppressant agents, LN still impairs the survival and quality of life in SLE patients. Receptor for advanced glycation endproducts (RAGE) is a multi-ligand receptor that belongs to the immunoglobulin superfamily, which is strongly associated with innate immune system. In the present study, we examined whether RAGE is involved in the development of LN. Further, we explored the therapeutic impact of DNA-aptamer directed against RAGE on lupus-related kidney injury. Methods: [Protocol 1] RAGE expression in kidneys and urinary RAGE excretion (uRAGE) were determined at 8, 12, 16, 18, 20-week-old by real-time PCR and ELISA, respectively in MRL/lpr, SLE-prone mice. [Protocol 2] LN was induced by peritoneally injecting pristane in wild type and RAGE globally knockout mice. [Protocol 3] MRL/lpr mice were subcutaneously administrated with DNA-aptamer raised against RAGE (RAGE-apt) or Control-aptamer (Ctrl-apt) for 10weeks. Results: [Protocol 1] uRAGE levels, but not urinary protein excretion, were significantly increased in 8-week-old MRL/lpr mice when compared to those in control MRL/MPJ mice, suggesting that uRAGE could be an early marker of LN.. Immunofluorescence staining demonstrated that RAGE was upregulated in distal tubules but not in glomerulus in 8-week-old mice. Glomerular RAGE expression was increased from 12-week-old with mesangial matrix expansion and formation of cellular crescents. RAGE expression was also found in endothelium and infiltrated macrophages in glomerulus while RAGE was merged with cathepsine D, a lysosomal aspartyl protease, and Rab7, a marker of late endocytosis in tubular epithelial cells. [Protocol 2] Pristane-induced increase in systolic blood pressure was reduced with improvement of renal dysfunction in RAGE knockouts. RAGE knockouts also showed less fibrosis with decrease in macrophage infiltration when compared to wild type mice in pristane-induced lupus nephritis. [Protocol 3] Administration of RAGE-apt ameliorated mesangial expansion, crescent formation, and macrophage infiltration into glomerulus in MRL/lpr mice. RAGE-apt, but not Ctrl-apt, reduced the level of pro-inflammatory cytokines gene expression including IL-6, TNF-α, and MCP-1 in renal cortex of MRL/lpr mice. Conclusion: RAGE could be involved in the pathogenesis of LN, and RAGE-DNA aptamer might be one of the promising therapeutic strategies for preventing the development of LN.

The Amphiregulin/EGFR axis protects from lupus nephritis via downregulation of pathogenic CD4+ T helper cell responses

Systemic lupus erythematosus (SLE) is a common autoimmune disorder with a complex and poorly understood immuno-pathogenesis. Lupus nephritis (LN) is a frequent and difficult to treat complication, which causes high morbidity and mortality. The multifunctional cytokine amphiregulin (AREG) has been implicated in SLE pathogenesis, but its function in LN currently remains unknown. We thus studied the model of pristane-induced LN and found increasing renal and systemic AREG expression during the course of disease. Importantly, renal injury was significantly aggravated in the absence of AREG, revealing a net anti-inflammatory role. Analyses of immune responses showed dual effects. On the one hand, AREG enhanced activation of pro-inflammatory myeloid cells, which however did not play a major role for the course of LN. More importantly, on the other hand, AREG strongly suppressed pathogenic cytokine production by T helper effector cells. This effect was more general in nature and could be reproduced in response to antigen immunization. Since AREG has been postulated to downregulate T cell responses via enhancing Treg suppressive capacity, we followed up on this aspect. Interestingly, however, in vitro studies revealed potential direct and Treg independent effects of AREG on T helper effector cells. In favor of this notion, we found significantly enhanced T cell responses and consecutive aggravation of LN, only if epidermal growth factor receptor (EGFR) signaling was abrogated in total T cells, but not if the EGFR was absent on Tregs alone. Finally, we also found enhanced AREG expression in plasma and renal biopsies of patients with LN, supporting the relevance of our findings for human disease. In summary, our data identify AREG as an anti-inflammatory mediator of LN via broad downregulation of pathogenic T cell immunity. These findings further highlight the AREG/EGFR axis as a potential therapeutic target.

Total Glucosides of Paeony Ameliorate Pristane-Induced Lupus Nephritis by Inducing PD-1 ligands+ Macrophages via Activating IL-4/STAT6/PD-L2 Signaling.

Macrophages, a major subset of innate immune cells, are main infiltrating cells in the kidney in lupus nephritis. Macrophages with different phenotypes exert diverse or even opposite effects on the development of lupus nephritis. Substantial evidence has shown that macrophage M2 polarization is beneficial to individuals with chronic kidney disease. Further, it has been reported that PD-1 ligands (PD-Ls) contribute to M2 polarization of macrophages and their immunosuppressive effects. Total glucosides of paeony (TGP), originally extracted from Radix Paeoniae Alba, has been approved in China to treat some autoimmune diseases. Here, we investigated the potentially therapeutic effects of TGP on lupus nephritis in a pristane-induced murine model and explored the molecular mechanisms regulating macrophage phenotypes. We found that TGP treatment significantly improved renal function by decreasing the urinary protein and serum creatinine, reducing serum anti-ds-DNA level and ameliorating renal immunopathology. TGP increased the frequency of splenic and peritoneal F4/80+CD11b+CD206+ M2-like macrophages with no any significant effect on F4/80+CD11b+CD86+ M1-like macrophages. Immunofluorescence double-stainings of the renal tissue showed that TGP treatment increased the frequency of F4/80+Arg1+ subset while decreasing the percentage of F4/80+iNOS+ subset. Importantly, TGP treatment increased the percentage of both F4/80+CD11b+PD-L1+ and F4/80+CD11b+PD-L2+ subsets in spleen and peritoneal lavage fluid as well as the kidney. Furthermore, TGP augmented the expressions of CD206, PD-L2 and phosphorylated STAT6 in IL-4-treated Raw264.7 macrophages in vitro while its effects on PD-L2 were abolished by pretreatment of the cells with an inhibitor of STAT6, AS1517499. However, TGP treatment did not affect the expressions of STAT1 and PD-L1 in Raw264.7 macrophages treated with LPS/IFN-γ in vitro, indicating a possibly indirect effect of TGP on PD-L1 expression on macrophages in vivo. Thus, for the first time, we demonstrated that TGP may be a potent drug to treat lupus nephritis by inducing F4/80+CD11b+CD206+ and F4/80+CD11b+PD-L2+ macrophages through IL-4/STAT6/PD-L2 signaling pathway.

5,6,7,8-Tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidine derivative attenuates lupus nephritis with less effect to thymocyte development.

Retinoic‑acid‑receptor‑related orphan nuclear hormone receptor gamma t (RORγt), a critical transcriptional factor of Th17 cells, is a potential therapeutic target for Th17-mediated autoimmune diseases. In addition, RORγt is essential for thymocyte survival and lymph node development, and RORγt inhibition or deficiency causes abnormal thymocyte development, thymus lymphoma, and lymph node defect. Recent study demonstrated that specific regulation of Th17 differentiation related to the hinge region of RORγt. In this research, we investigated the effect of RORγt inhibitor, 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidine derivative (TTP), in the therapy of lupus nephritis and its safety on thymocyte development. We demonstrated that TTP repressed the development of Th17 cells and ameliorated the autoimmune disease manifestation in the pristane-induced lupus nephritis mice model. The treatment of TTP in the mice did not interfere with thymocyte development, including total thymocyte number and proportion of CD4+CD8+ double-positive populations in the thymus, and had no substantial effects on the pathogenesis of thymoma. The TTP had a stronger affinity with full-length RORγt protein compared with the truncated RORγt LBD region via surface plasmon resonance, which indicated TTP binding to RORγt beyond LBD region. Molecular docking computation showed that the best binding pocket of TTP to RORγt is located in the hinge region of RORγt. In summary, as a RORγt inhibitor, TTP had a potential to develop the clinical medicine for treating Th17-mediated autoimmune diseases with low safety risk for thymocyte development.

Preclinical Testing of Viral Therapeutic Efficacy in Pristane-Induced Lupus Nephritis and Diffuse Alveolar Hemorrhage Mouse Models.

Systemic lupus erythematosus (SLE) is a multifactorial and heterogeneous autoimmune disease involving multiple organ systems and tissues. Lupus nephritis occurs in approximately 60% of patients with SLE and is the leading cause of morbidity. Diffuse alveolar hemorrhage (DAH) is a rare but very serious complication of SLE with a greater than 50% associated mortality. The etiology of SLE is unclear but has proposed genetic, hormonal, and environmental aspects. Pristane is a saturated terpenoid alkane and has become the most popular laboratory model for inducing lupus in mice. The pristane model of SLE has the capacity to reproduce many components of the human presentation of the disease. Previous studies have demonstrated that virus-derived immune-modulating proteins have the potential to control inflammatory and autoimmune disorders. Serp-1, a 55kDa secreted and highly glycosylated immune modulator derived from myxoma virus (MYXV), has potent immunomodulatory activity in models of vasculitis, viral sepsis, collagen-induced arthritis, and transplant rejection. This chapter describes the mouse preclinical pristane lupus model as a method to examine virus-derived protein efficacy for treating autoimmune diseases and specifically lupus nephritis and DAH.

Expression of XBP1s in B lymphocytes is critical for pristane-induced lupus nephritis in mice.

B lymphocyte hyperactivity plays a pathogenic role in systemic lupus erythematosus (SLE), and spliced X box-binding protein 1 (XBP1s) has been implicated in B cell maturation and differentiation. We hypothesized that blockade of the XBP1s pathway inhibits the B cell hyperactivity underlying SLE and lupus nephritis (LN) development. In the present study, we systematically evaluated the changes in B cell activation induced by the Xbp1 splicing inhibitor STF083010 in a pristane-induced lupus mouse model. The lupus mouse model was successfully established, as indicated by the presence of LN with markedly increased urine protein levels, renal deposition of Ig, and mesangial cell proliferation. In lupus mice, B cell hyperactivity was confirmed by increased CD40 and B cell-activating factor levels. B cell activation and plasma cell overproduction were determined by increases in CD40-positive and CD138-positive cells in the spleens of lupus mice by flow cytometry and further confirmed by CD45R and Ig light chain staining in the splenic tissues of lupus mice. mRNA and protein expression of XBP1s in B cells was assessed by real-time PCR, Western blot analysis, and immunofluorescence analysis and was increased in lupus mice. In addition, almost all changes were reversed by STF083010 treatment. However, the expression of XBP1s in the kidneys did not change when mice were exposed to pristane and STF083010. Taken together, these findings suggest that expression of XBP1s in B cells plays key roles in SLE and LN development. Blockade of the XBP1s pathway may be a potential strategy for SLE and LN treatment.

α-mangostin attenuates pristane-induced lupus nephritis by regulating Th17 differentiation.

α-mangostin, a polyphenolic xanthone derivative of mangosteen, has been reported to possess multiple therapeutic properties, such as anti-cancer, anti-allergy and anti-inflammatory activity. However, its anti-inflammatory effects in autoimmune diseases such as lupus nephritis (LN) remain unclear. In this study, we want to investigate the therapeutic effect of α-mangostin in LN. First, we elucidated the retinoic acid receptor related orphan receptor gamma t (RORγt) inhibitory activity of α-mangostin in cell-based assay and T helper 17 (Th17) differentiation in vitro assay. Then, we established a pristane-induced LN mouse model and randomly divided these into a normal control group, model control group, α-mangostin group and prednisone acetate group. Finally, anti-double-stranded DNA (anti-dsDNA) level in serum was detected by enzyme-linked immunosorbent assay, interleukin (IL)-17A and interferon (IFN)-γ expression in spleen cells by flow cytometry; histomorphology examination of kidneys was performed by periodic acid-Schiff staining and immunofluorescence analysis with an anti-immunoglobulin G (anti-IgG) and anti-IgM antibodies. We found that α-mangostin inhibited RORγt transcription activity in a cell-based assay and also polarized Th17 cells in an in vitro induction experiment. Our results also showed that α-mangostin could significantly decrease serum anti-dsDNA antibody levels, IL-17A and IFN-γ expression and alleviate renal pathological damage in the α-mangostin-treated group mice than in the model group mice. Thus, α-mangostin demonstrated its potential as a candidate therapeutic drug for LN and other Th17-mediated autoimmune diseases by inhibiting the function of Th17.

NLRP3 Inflammasome Modulation by Melatonin Supplementation in Chronic Pristane-Induced Lupus Nephritis.

Lupus nephritis (LN) is a kidney inflammatory disease caused by systemic lupus erythematosus (SLE). NLRP3 inflammasome activation is implicated in LN pathogenesis, suggesting its potential targets for LN treatment. Melatonin, an endogenous indoleamine, is considered an important multitasking molecule that has been reported to have anti-inflammatory effects by inhibiting nuclear factor-kappa B (NF-κB)-mediated inflammatory responses in vivo. This molecule has also protective effects against the activation of the inflammasomes and, in particular, the NLRP3 inflammasome. Thus, this work evaluated the effect of melatonin on morphological alteration and NLRP3 inflammasome activation in LN pristane mouse models. To evaluate the melatonin effects in these mice, we studied the renal cytoarchitecture by means of morphological analyses and immunohistochemical expression of specific markers related to oxidative stress, inflammation and inflammasome activation. Our results showed that melatonin attenuates pristane-induced LN through restoring of morphology and attenuation of oxidative stress and inflammation through a pathway that inhibited activation of NLRP3 inflammasome signaling. Our data clearly demonstrate that melatonin has protective activity on lupus nephritis in these mice that is highly associated with its effect on enhancing the Nrf2 antioxidant signaling pathway and decreasing renal NLRP3 inflammasome activation.

3β-Acetyloxy-oleanolic Acid Attenuates Pristane-Induced Lupus Nephritis by Regulating Th17 Differentiation.

Th17 activity has been implicated in systemic lupus erythematosus (SLE), which is a systemic autoimmune disease with a typical clinical manifestation of lupus nephritis (LN). Retinoic acid receptor-related orphan receptor gamma t (RORγt) has been shown to be important for Th17 differentiation. In this study, we evaluated the inhibition of RORγt activity by 3β-acetyloxy-oleanolic acid (AOA), a small molecule isolated from the root of Symplocos laurina, a traditional herb belonging to South China. We demonstrated that AOA can inhibit RORγt activity and prevent SLE pathogenesis in a pristane-induced LN model. The results showed that AOA decreased RORγt transcription activity in a reporter assay and prevented Th17 differentiation in vitro. In vivo studies showed that AOA treatment decreased serum anti-dsDNA antibody and alleviated renal pathologic damage as well as antibody complex accumulation in the pristane-induced LN model. These results demonstrated that AOA can improve the clinical manifestation of LN, indicating potential application in SLE therapy.

Baicalein ameliorates pristane-induced lupus nephritis via activating Nrf2/HO-1 in myeloid-derived suppressor cells

IntroductionLupus nephritis (LN) is a representative manifestation in systemic lupus erythematosus (SLE). Some studies have shown that myeloid-derived suppressor cells (MDSCs) play a vital role in the regulation of the SLE process. MDSC infiltration in the kidney as well as inflammation and oxidative stress provokes the acceleration and deterioration of LN. Nuclear factor E2-related factor 2 (Nrf2) is thought to be a major regulator of the antioxidant response. Baicalein is a flavonoid with known anti-inflammatory effects and antioxidant response. However, the effects of baicalein on MDSCs, inflammation, and oxidative stress are not evaluated in the development of pristane-induced LN in mice.MethodsThe renoprotective effect of baicalein was detected in a pristane-induced lupus mice model. NLRP3 inflammasome activation and NF-κB phosphorylation as well as reactive oxygen species (ROS) production and Nrf2 activation were examined. The percentages and function changes of MDSCs were measured. The possible mechanisms of the underlying effects of baicalein on ROS production and signaling pathways of Nrf2/heme-oxygenase (HO)-1, NLRP3 inflammasome, and NF-κB phosphorylation in lipopolysaccharide (LPS)-primed MDSCs were analyzed.ResultsBaicalein reduced proteinuria and attenuated renal function impairment and renal histopathology including intrinsic cell proliferation, cellular crescents, and podocyte injury as well as glomerulonephritis activity in lupus mice. Moreover, baicalein downregulated the activation of NLRP3 inflammasome and levels of ROS or NF-κB phosphorylation, and it enhanced Nrf2 activation. Of note, baicalein inhibited the expansion of MDSCs and improved the function of MDSCs in lupus mice. Through analyzing LPS-primed MDSCs in vitro, baicalein was found to exhibit cytoprotective effects coincident with the induction of Nrf2/HO-1 signaling and the suppression of the NLRP3 inflammasome.ConclusionThe data show that baicalein alleviates the symptoms of pristane-induced LN and suggest that the alleviation may be attributed to inhibition of MDSC expansion and regulation of the balance of the Nrf2/HO-1 signal and NLRP3 expression in MDSCs.

IL-17C/IL-17 Receptor E Signaling in CD4+ T Cells Promotes TH17 Cell-Driven Glomerular Inflammation.

The IL-17 cytokine family and the cognate receptors thereof have a unique role in organ-specific autoimmunity. Most studies have focused on the founding member of the IL-17 family, IL-17A, as the central mediator of diseases. Indeed, although pathogenic functions have been ascribed to IL-17A and IL-17F in the context of immune-mediated glomerular diseases, the specific functions of the other IL-17 family members in immunity and inflammatory kidney diseases is largely unknown. Here, we report that compared with healthy controls, patients with acute Anti-neutrophil cytoplasmatic antibody (ANCA)-associated crescentic glomerulonephritis (GN) had significantly elevated serum levels of IL-17C (but not IL-17A, F, or E). In mouse models of crescentic GN (nephrotoxic nephritis) and pristane-induced lupus nephritis, deficiency in IL-17C significantly ameliorated the course of GN in terms of renal tissue injury and kidney function. Deficiency of the unique IL-17C receptor IL-17 receptor E (IL-17RE) provided similar protection against crescentic GN. These protective effects associated with a reduced TH17 response. Bone marrow transplantation experiments revealed that IL-17C is produced by tissue-resident cells, but not by lymphocytes. Finally, IL-17RE was highly expressed by CD4+ TH17 cells, and loss of this expression prevented the TH17 responses and subsequent tissue injury in crescentic GN. Our findings indicate that IL-17C promotes TH17 cell responses and immune-mediated kidney disease via IL-17RE expressed on CD4+ TH17 cells. Targeting the IL-17C/IL-17RE pathway may present an intriguing therapeutic strategy for TH17-induced autoimmune disorders.

Protective effects of quercetin treatment in a pristane-induced mouse model of lupus nephritis

Introduction: Lupus nephritis (LN) is one of the most severe complications of systemic lupus erythematosus. As murine models of LN are valuable tools to better understand its pathophysiology and to search for new effective treatments, we investigated the effects of the bioflavonoid quercetin on pristane-induced LN mice through histomorphological analyses.Methods: Immunofluorescence and biochemical assays were used to evaluate the expression of markers of inflammation (interleukin-6, IL-6; tumour necrosis factor-α, TNF-α), oxidative stress (catalase, CAT; superoxide dismutase 1, SOD1; thiobarbituric acid reactive substances, TBARS), apoptosis (Bax), and fibrosis (transforming growth factor-β1, TGF-β1). Glomerular and tubular ultrastructure was analysed, and tissue messenger RNA of podocin, podoplanin and α3β1-integrin were quantified using the real-time polymerase chain reaction.Results: Pristane-induced LN mice showed severe kidney injury, characterized by increased proteinuria, glomerular mesangial expansion and inflammation, high expression of the pro-fibrotic, apoptotic and prooxidant markers and reduction of antioxidants. In the kidney ultrastructure, foot process (FP) effacement, apoptotic mesangial cells and abnormal mitochondria with disrupted cristae were observed, along with suppressed tissue mRNA of podocin, podoplanin and α3β1-integrin. Treatment with quercetin in the pristane-induced LN mice model was nephroprotective, decreasing proteinuria levels and significantly lowering tissue expression of IL-6, TNF-α, TGF-β1, Bax and TBARS. Simultaneously, quercetin significantly increased CAT and SOD1 expressions in these mice. In addition, it was observed improvement of the kidney ultrastructure, and tissue mRNA of podocin, but not podoplanin and α3β1-integrin, was restored to the levels found in the control mice.Conclusion: In conclusion, these findings provide experimental evidence of the renoprotective effects of quercetin in the pristane-induced LN mice model. We suggest that quercetin effectively ameliorates the kidney damage caused by pristane, a bioflavonoid to be further evaluated as a new therapeutic strategy in this disease.

Oral supplementation of melatonin protects against lupus nephritis renal injury in a pristane-induced lupus mouse model

AimsSince lupus nephritis (LN) etiopathogenesis is not fully understood, herein we investigated the morphological basis of LN in mice induced with pristane. Main methodsTo evaluate the melatonin effects in these animals, we studied the renal cytoarchitecture by means of morphological analyses, immunofluorescence expression of specific markers related to fibrosis, oxidative stress, inflammation and apoptosis. Key findingsWe observed that pristane-LN mice have serious alterations in the kidney cytoarchitecture, i.e. tubular degeneration, glomerular hypercellularity, matrix mesangial expansion and interstitial inflammation. The pristane-induced LN mice treated with melatonin exhibited a well preserved cytoarchitecture. SignificanceOur results document that LN etiopathogenesis is related to both tubular damage and glomerular lesions. We suggest that it is essential to take in consideration both these lesions for LN diagnosis and classification. Clearly, we show that the use of melatonin may be a possible therapeutic strategy for improvement the renal injury in this disorder.

Basophils contribute to pristane-induced Lupus-like nephritis model

Lupus nephritis (LN), one of the most severe outcomes of systemic lupus erythematosus (SLE), is initiated by glomerular deposition of immune-complexes leading to an inflammatory response and kidney failure. Autoantibodies to nuclear antigens and autoreactive B and T cells are central in SLE pathogenesis. Immune mechanisms amplifying this autoantibody production drive flares of the disease. We previously showed that basophils were contributing to LN development in a spontaneous lupus-like mouse model (constitutive Lyn−/− mice) and in SLE subjects through their activation and migration to secondary lymphoid organs (SLOs) where they amplify autoantibody production. In order to study the basophil-specific mechanisms by which these cells contribute to LN development, we needed to validate their involvement in a genetically independent SLE-like mouse model. Pristane, when injected to non-lupus-prone mouse strains, induces a LN-like disease. In this inducible model, basophils were activated and accumulated in SLOs to promote autoantibody production. Basophil depletion by two distinct approaches dampened LN-like disease, demonstrating their contribution to the pristane-induced LN model. These results enable further studies to decipher molecular mechanisms by which basophils contribute to lupus progression.