Vasoactive intestinal peptide ameliorates renal injury in a pristane-induced lupus mouse model by modulating Th17/Treg balance

The roles of adenosine signaling in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease with multiple etiological factors. Immune disorder contributes to SLE development and is an important clinical manifestation of SLE patients. Immune dysfunction is characterized by abnormal of B cells, T cells, monocyte-macrophages and dendritic cells (DCs), in both quantity and quality. Adenosine is a critical factor for human immune homeostasis, which acts as an immunosuppressive signal and can prevent the hyperactivity of human immune system. Adenosine levels are significant decreased in serum from SLE patients. Adenosine level is regulated by the CD39, CD73 and adenosine deaminase (ADA). CD39/CD73/ADA catalyzed the cascade enzymatic reaction, which contained the adenosine generation and degradation. Adenosine affects the function of various immune cells via bind to the adenosine receptors, which are expressed on the cell surface. This review aims to export the changes of immune cells and adenosine signal pathway in SLE, as well as the effect of adenosine signal pathway in SLE development.

Pathogenesis and novel therapeutics of regulatory T cell subsets and interleukin-2 therapy in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a heterogeneous multisystem inflammatory disease with wide variability in clinical manifestations. Natural arising CD4+ regulatory T cells (Tregs) play a critical role in maintaining peripheral tolerance by suppressing inflammation and preventing autoimmune responses in SLE. Additionally, CD8+ regulatory T cells, type 1 regulatory T cells (Tr1), and B regulatory cells also have a less well-defined role in the pathogenesis of SLE. Elucidation of the roles of various Treg subsets dedicated to immune homeostasis will provide a novel therapeutic approach that governs immune tolerance for the remission of active lupus. Diminished interleukin (IL)-2 production is associated with a depleted Treg cell population, and its reversibility by IL-2 therapy provides important reasons for the treatment of lupus. This review focuses on the pathogenesis and new therapeutics of human Treg subsets and low-dose IL-2 therapy in clinical benefits with SLE.

Lactobacillus plantarum CQPC02 intervenes in mouse lupus nephritis by regulating the NF-κB signaling pathway

A strain of Lactobacillus plantarum CQPC02 (LP-CQPC02) isolated from naturally fermented kimchi was utilized in this investigation. In order to construct an animal model of lupus nephritis, pristane was used. We then used a kit to identify markers in mouse blood and tissues and a quantitative polymerase chain reaction (qPCR) to measure the expression of genes associated to nuclear factor kappa-B (NF-κB) in mouse kidney tissue. According to the results of the experiments, oral administration of LP-CQPC02 LP-CQPC02 may lessen the lupus nephritis-related rise in urine protein as well as the cytokine levels that were rising in the serum and renal tissues, including IL-6, IL-12, tumor necrosis factor alpha, and interferon. Additionally, in mice with nephritis, LP-CQPC02 can lower serum creatinine (SCr), blood urea nitrogen (BUN), total cholesterol (TC), triglyceride (TG), and raise total protein (TP) and albumin (ALB) levels. In mice with nephritis, LP-CQPC02 can also reduce the positive rate of double-stranded deoxyribonucleic acid (dsDNA). Pathological sections were examined, and it was shown that LP-CQPC02 can lessen tissue damage such incomplete glomerular morphology and inflammatory infiltration brought on by nephritis. In the kidneys of mice with lupus nephritis, LP-CQPC02 can upregulate the expression of inhibitor of NF-κB (IκB-α), downregulate the expression of NF-κB, transforming growth factor-β1 (TGF-β1), vascular endothelial growth factor (VEGF), intercellular cell adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1). Lactobacillus plantarum CQPC02 has been confirmed to have an intervention effect on nephritis in mice and has the potential as a probiotic.

Asiaticoside ameliorates renal ischemia/reperfusion injury by promoting CD4+CD25+FOXP3+ treg cell differentiation

Ischemia/reperfusion injury (I/R) is the major cause of acute kidney injury, which becomes a global health problem. The effects of asiaticoside, as an anti-inflammatory drug, on renal ischemia-reperfusion injury have not been well defined. After the CD4+ cells were treated with asiaticoside, the CD4+CD25+FOXP3+ Treg cell differentiation was detected by flow cytometry. The viability and release of inflammatory factors of CD4+CD25+FOXP3+ Treg cell were detected by CCK-8 and ELISA. Renal I/R injury mice model was established, and the mice were pre-treated with asiaticoside or CD25 antibody or infused with Treg cells. The histological changes of renal tissue were evaluated by Hematoxylin-eosin, PAS, and Masson staining. The renal function markers were evaluated by colorimetry, the release of inflammatory factors was determined by ELISA. The Th17 and Treg cells in the blood and spleen were quantified by flow cytometry. The expressions of FOXP3 and RoR-γt in renal tissues were determined by western blotting. Asiaticoside promoted CD4+CD25+FOXP3+ Treg cell differentiation, increased the cell viability and down-regulated TNF-α, IL-1β, and IL-6, while up-regulated IL-10 of CD4+CD25+FOXP3+ Treg cells. Moreover, asiaticoside ameliorated the histological damage, decreased the Th17 cells and increased Treg cells, and down-regulated the TNF-α, IL-1β, IL-6, blood urea nitrogen, serum creatinine, and RoR-γt, while up-regulated IL-10 and FOXP3 of renal I/R injury mice. Effect of asiaticoside on renal I/R injury mice was reversed by CD25 antibody whose role was further reversed by Treg cell infusing. In conclusion, asiaticoside ameliorated renal I/R injury due to promoting CD4+CD25+FOXP3+ Treg cell differentiation.

Research on the mechanism of prednisone in the treatment of ITP via VIP/PACAP-mediated intestinal immune dysfunction

RATIONALE

Immune thrombocytopenia (ITP) is thought to be a result of immune dysfunction, which is treated by glucocorticoids such as prednisone. Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) have immunomodulatory properties, but their role in intestinal immune control is unclear. The major goal of this study was to look at the effects of prednisone on platelet, VIP, and PACAP levels in ITP mice, as well as the regulatory system that controls intestinal immunity.

METHODS

Eighteen BALB/c mice were randomly divided into three groups: blank control group, model control group, and prednisone group, with six mice in each group. The ITP animal model control group and the prednisone group were injected with anti-platelet serum (APS) to replicate the ITP animal model. The prednisone group began prednisone intervention on the 8th day. Platelet count was dynamically measured before APS injection, on the 4th day of injection, on the 1st day of administration, on the 4th day of administration, and at the end of the experiment. After the experiment, the expression of p53 protein in mouse mesenteric lymph node lymphocytes was detected by immunohistochemistry. The changes in lymphocyte apoptosis rate in mouse mesenteric lymph nodes were detected by in situ terminal transferase labeling (TUNEL). The contents of VIP and PACAP in the mouse brain, colon, and serum were detected by enzyme-linked immunosorbent assay (ELISA). The contents of IFN-γ, IL-4, IL-10, IL-17A in the mouse spleen were detected by ELISA.

RESULTS

①Changes of peripheral platelet count: there was no significant difference in platelet count among the three groups before modeling; on the 4th day, the platelet count decreased in the model control group and prednisone group; on the 8th day, the number of platelets in model control group and prednisone group was at the lowest level; on the 12th day, the platelet count in prednisone group recovered significantly; on the 15th day, the platelet count in prednisone group continued to rise. ②Changes of VIP, PACAP: compared with the blank control group, VIP and PACAP in the model control group decreased significantly in the brain, colon, and serum. Compared with the model control group, the levels of VIP and PACAP in the brain, colon, and serum in the prednisone group were increased except for serum PACAP. ③Changes of mesenteric lymphocytes: the expression of p53 protein in the mesenteric lymph nodes of model control group mice was significantly higher than that of blank control group mice. After prednisone intervention, the expression of p53 protein decreased significantly.④Changes of cytokines in spleen: compared with blank control group, IFN- γ, IL-17A increased and IL-4 and IL-10 decreased in model control group. After prednisone intervention, IFN- γ, IL-17A was down-regulated and IL-4 and IL-10 were upregulated.

CONCLUSIONS

Prednisone-upregulated VIP and PACAP levels decreased P53 protein expression and apoptosis rate in mesenteric lymph node lymphocytes and affected cytokine expression in ITP model mice. Therefore, we speculate that the regulation of intestinal immune function may be a potential mechanism of prednisone in treating ITP.

YY1 alleviates lupus nephritis-induced renal injury by reducing the Th17/Treg cell ratio via the IFN-γ/Fra2 axis

Lupus nephritis (LN) is associated with extensive injury and nephron loss in the afflicted kidney. Evidence has revealed the involvement of dysregulated Yin Yang 1 (YY1), a reported inflammatory modulator, in LN-induced kidney injury, and our microarray profile identified downregulated YY1 expression. Therefore, this study explored the functional relevance and mechanism of YY1 in LN-induced kidney injury. LN was modeled in mice by intraperitoneal injection of pristane, and Jurkat cells (CD41 human T lymphocytes) were activated with TNF-α to mimic the inflammatory environment found in LN. The expression patterns of YY1 and bioinformatics predictions of the downstream factor IFN-γ were confirmed in renal tissues from the mice with LN using qRT-PCR and Western blot analyses. The contents of proinflammatory cytokines in mouse serum samples and cell supernatants were determined using enzyme-linked immunosorbent assays (ELISAs). Ectopic expression and depletion approaches were subsequently used in vitro and in vivo to examine the effects of the YY1/IFN-γ/Fra2/PARP-1/FOXO1 axis on TNF-α-induced inflammation and LN-induced kidney injury. The results showed downregulated expression of YY1 and FOXO1 in the kidney tissues of the mice with LN. Increased proinflammatory factor production was observed in the mice with LN and TNF-α-treated Jurkat cell supernatant, accompanied by increased cell apoptosis and a high ratio of Th17/Treg cells, and these effects were reversed by YY1 restoration. YY1 was further shown to inhibit IFN-γ expression and thereby downregulate Fra2 expression. Fra2 depletion then inhibited PARP-1 expression and promoted FOXO1 expression to suppress cell apoptosis and the release of inflammatory factors. Collectively, our findings revealed that YY1 may alleviate LN-induced renal injury via the IFN-γ/Fra2/PARP-1/FOXO1 axis.

Effects of Lactobacillus plantarum HFY15 on Lupus Nephritis in Mice by Regulation of the TGF-β1 Signaling Pathway

Objective

In this study, the Lactobacillus plantarum HFY15 (LP-HFY15) strain isolated from naturally fermented yak yogurt was investigated. An animal model of lupus nephritis was established by pristane to verify the interventional effect of LP-HFY15 on mouse lupus nephritis by regulating the transforming growth factor-β1 (TGF-β1) signaling pathway.

Materials and Methods

Indexes in mouse serum and tissues were detected by kits, pathological changes in mouse kidney were observed by hematoxylin-eosin (H&E) staining, and quantitative polymerase chain reaction (qPCR) was used to detect TGF-β 1-related expression in mouse kidney tissue, which further elucidated the mechanism of LP-HFY15.

Results

LP-HFY15 decreased the elevation of urinary protein and the levels of interleukin-6 (IL-6), IL-12, tumor necrosis factor alpha (TNF-α), and interferon γ (IFN-γ) in serum and kidney tissue. LP-HFY15 also reduced serum creatinine (SCr), blood urea nitrogen (BUN), total cholesterol (TC), triglyceride (TG), and raised total protein (TP), and albumin (ALB) levels in mice with nephritis. In addition, LP-HFY15 inhibited the positive rate of double-stranded deoxyribonucleic acid (dsDNA) antibodies in mice with nephritis. The observation of H&E sections showed that LP-HFY15 alleviated the glomerulus morphological incompleteness and inflammatory infiltration caused by nephritis. Further results showed that LP-HFY15 downregulated the mRNA expression of TGF-β1, vascular endothelial growth factor (VEGF), and nuclear factor kappa-B (NF-κB) in the kidneys of lupus nephritis mice, and the expression of inhibitor of NF-κB (IκB-α), copper/zinc superoxide dismutase (Cu/Zn-SOD), and manganese superoxide dismutase (Mn-SOD) was also upregulated.

Conclusion

These results indicated that LP-HFY15 plays a significant role in experimental intervention for lupus nephritis. The effect of LP-HFY15 was positively correlated with its concentration, and the effect was similar to that of prednisone at 10⁹ CFU/kg.

Depletion of Fractalkine ameliorates renal injury and Treg cell apoptosis via the p38MAPK pathway in lupus-prone mice

Fractalkine (FKN) is a chemokine with several roles, including chemotaxis; adhesion; and immune damage, which also participates in cell inflammation and apoptosis and responds to the pathogenesis of autoimmune diseases. Given the involvement of regulatory T cells (Treg) cells in autoimmune diseases, this study investigated the regulatory mechanism of FKN in renal injury and Treg apoptosis via the p38 mitogen-activated protein kinase (p38MAPK) signaling pathway in lupus-prone mice. Lupus was induced in BALB/c female mice by injection of pristane, followed by isolation of CD4+CD25+ Treg cells from the spleen of lupus model mice. To deplete FKN, mice received injection of an anti-FKN antibody, and Treg cells were transfected with FKN small-interfering RNA. Lupus mice and Treg cells were treated with the p38MAPK inhibitor SB203580 and activator U-46619, respectively, and urine protein and serum urea nitrogen, creatinine, and autoantibodies were measured and renal histopathological changes analyzed. We determined levels of FKN, phosphorylated p38 (p-p38), and forkhead box P3 (FOXP3) in renal tissue and Treg cells, and analyzed apoptosis rates and levels of key apoptotic factors in Treg cells. The renal FKN and p-p38 levels increased, whereas renal FOXP3 level decreased in lupus-prone mice. Treatment with the anti-FKN antibody and the p38MAPK inhibitor ameliorated proteinuria and renal function, significantly reducing serum autoantibody, renal FKN, and p-p38 levels while increasing renal FOXP3 level in lupus-prone mice. Moreover, FKN knockdown and administration of the p38MAPK inhibitor reduced apoptosis and levels of pro-apoptotic factors, increased levels of anti-apoptotic factors, and suppressed activation of p38MAPK signaling in Treg cells derived from lupus model mice. Furthermore, treatment with the p38MAPK activator U-46619 had the opposite effect on these cells. These data indicated that depletion of FKN ameliorated renal injury and Treg cell apoptosis via inhibition of p38MAPK signaling in lupus nephritis, suggesting that targeting FKN represents a potential therapeutic strategy for treating Lupus nephritis.

Metformin improves FOXP3 mRNA expression through suppression of interferon gamma levels in pristane-induced murine models of lupus

Background:  A recent study has indicated the potential of metformin therapy for lupus in animal models, but there has been no study evaluating the effect on pristane-induced lupus. This study aims to evaluate the effect of intraperitoneal versus oral metformin on interferon (IFN)-γ levels and FOXP3 mRNA expression on pristane-induced female BALB/c mice.

Methods: In total, 31 female BALB/c mice, aged 6 weeks, were intraperitoneally induced with 0.5 ml of pristane (2,6,10,14-tetramethylpentadecane). After 120 days, the mice were grouped and treated with various treatments: normal saline 100 MCL, oral metformin 100mg/kg-BW, or intraperitoneal metformin 100mg/kg-BW. After 60 days of treatment, all treatment groups were sacrificed, and kidney specimens prepared and stained using hematoxylin and eosin.

Results: IFNγ levels of saline controls vs. oral metformin group was 309.39 vs. 292.83 pg/mL (mean difference 16.56 pg/mL; 95% CI 0.74-32.37; p=0.042), and saline control vs. intraperitoneal metformin group was 309.39 vs. 266.90 pg/mL (mean difference 42.49 pg/mL; 95% CI 29.24-55.73 pg/mL; p<0.001). FOXP3 mRNA expression changes in saline controls vs. oral metformin group was 6.90 vs. 7.79-fold change (mean difference -0.89-fold change; 95% CI -1.68-(-0.11); p=0.03)  and in saline controls vs. intraperitoneal metformin group was 6.90 vs. 9.02-fold change (mean difference -2.12-fold change; 95% CI -2.99-(-1.25); p=<0.001). Correlation analysis of FOXP3 mRNA expression and IFNγ level changes revealed a Pearson correlation of -0.785 (p=0.001) and R2 value of 0.616 (p=0.001).

Conclusion: Metformin is a potential new therapy to reduce the levels of IFNγ and increase FOXP3 mRNA expression in mice models of systemic lupus erythematosus.

Cucurbitacin IIb improved active chromatin-induced systemic lupus erythematosus via balancing the percentage of Th17 and Treg cells

The pathogenesis of systemic lupus erythematosus (SLE) is closely associated with aberrant immune system. Here, the aim of our study was to explore the regulation of cucurbitacin IIb (CuIIb) to Th17/Treg cells in SLE. Compared with normal mice, the percentage of Treg cells was downregulated in SLE mouse model, and Th17 was upregulated. Meantime, the production of Treg-related transcription factor (foxp3) in SLE model mouse was reduced, and the production of Th17-related transcription factor (RORγt) was increased. After treatment with CuIIb, the percentage of Treg cells in SLE mice was partly upregulated, and Th17 cells percentage was downregulated. The expression of foxp3 and RORγt in SLE mice were promoted and inhibited by CuIIb treatment, respectively. SLE-induced kidney injury also was improved by CuIIb treatment. In vitro, we demonstrated again that CuIIb upregulated the percentage of Treg cells in lymphocytes from SLE mice, and downregulated the percentage of Th17 cells. Highly expressed IL-6 and IL17, and lowly expressed IL-10 and TGF-β in lymphocytes from SLE mice were repressed and facilitated by CuIIb treatment, respectively. Overall, our data proved that CuIIb improved kidney injury in SLE mice through balancing the percentage of Th17 and Treg cells. Our data provided a reliable evidence to support the potential of CuIIb in SLE treatment.

Fractalkine mediates lymphocyte inflammation and tubulointerstitial lesions by modifying the Treg/Th17 balance in lupus-prone MRL/lpr mice

In this study, we first analyzed the expression level of fractalkine (FKN) in the serum of patients with lupus nephritis (LN) and the distribution of peripheral blood Treg cells, and explored FKN and Treg cells, systemic lupus erythematosus disease activity index 2000 (SLEDAI-2K) correlation. Subsequently, we explored the specific role of FKN in tubule interstitial lesions (TILs) and regulatory T (Treg) cells/T helper (Th) 17 cell balance in lupus model mice. Treated with an anti-FKN antibody (aFKN), recombinant FKN (rFKN), or an isotype antibody (IgG) in MRL/MpJ-Faslpr/J and C57BL/6 mice, and then detected TIL level and forkhead box p3 (Foxp3), IL-10, IL-17 and IL-6 expression levels in the kidney and spleen in the proportion of Treg and Th17 cells. Finally, then use aFKN, rFKN, or IgG to intervene in polarized Tregs with IL-6, TGF-β, IL-23, anti-interferon, and Th17 cells with anti-IL-4 after transforming to transform growth factor (TGF)-β and interleukin (IL)-2 in isolated mouse spleen lymphocytes. The results showed that the expression level of FKN was positively correlated with SLEDAI-2K and negatively correlated with the distribution of Treg cells. After treatment with aFKN in lupus model mice, kidney damage was delayed, TIL formation was reduced, Foxp3 and IL-10 levels were up-regulated, IL-17 and IL-6 levels were down-regulated in renal tissues, Th17 cell subsets and Treg cell subsets were reduced The increase is in the spleen, and rFKN treatment has the opposite effect in mouse. In addition, after interfering with polarized cells by aFKN, it was found that IL-17 and IL-6 expression levels were down-regulated in Th17 cells, Foxp3 and IL-10 levels in Tregs were up-regulated, and rFKN treatment had the opposite effect in vitro. These results indicate that FKN participates in and promotes SLE target organ damage including: secretion of inflammatory factors and renal TIL, and most importantly, these effects might have been due to modification of the Treg/Th17 cell balance.

Metformin improves FOXP3 mRNA expression through suppression of interferon gamma levels in pristane-induced murine models of lupus

Background:  A recent study has indicated the potential of metformin therapy for lupus in animal models, but there has been no study evaluating the effect on pristane-induced lupus. This study aims to evaluate the effect of intraperitoneal versus oral metformin on interferon (IFN)-γ levels and FOXP3 mRNA expression on pristane-induced female BALB/c mice. Methods: In total, 31 female BALB/c mice, aged 6 weeks, were intraperitoneally induced with 0.5 ml of pristane (2,6,10,14-tetramethylpentadecane). After 120 days, the mice were grouped and treated with various treatments: normal saline 100 MCL, oral metformin 100mg/kg-BW, or intraperitoneal metformin 100mg/kg-BW. After 60 days of treatment, all treatment groups were sacrificed, and kidney specimens prepared and stained using hematoxylin and eosin. Results: IFNγ levels of saline controls vs. oral metformin group was 309.39 vs. 292.83 pg/mL (mean difference 16.56 pg/mL; 95% CI 0.74-32.37; p=0.042), and saline control vs. intraperitoneal metformin group was 309.39 vs. 266.90 pg/mL (mean difference 42.49 pg/mL; 95% CI 29.24-55.73 pg/mL; p<0.001). FOXP3 mRNA expression changes in saline controls vs. oral metformin group was 6.90 vs. 7.79-fold change (mean difference -0.89-fold change; 95% CI -1.68-(-0.11); p=0.03)  and in saline controls vs. intraperitoneal metformin group was 6.90 vs. 9.02-fold change (mean difference -2.12-fold change; 95% CI -2.99-(-1.25); p=<0.001). Correlation analysis of FOXP3 mRNA expression and IFNγ level changes revealed a Pearson correlation of -0.785 (p=0.001) and R2 value of 0.616 (p=0.001). Conclusion: Metformin is a potential new therapy to reduce the levels of IFNγ and increase FOXP3 mRNA expression in mice models of systemic lupus erythematosus.

A Clinical Approach for the Use of VIP Axis in Inflammatory and Autoimmune Diseases

The neuroendocrine and immune systems are coordinated to maintain the homeostasis of the organism, generating bidirectional communication through shared mediators and receptors. Vasoactive intestinal peptide (VIP) is the paradigm of an endogenous neuropeptide produced by neurons and endocrine and immune cells, involved in the control of both innate and adaptive immune responses. Exogenous administration of VIP exerts therapeutic effects in models of autoimmune/inflammatory diseases mediated by G-protein-coupled receptors (VPAC1 and VPAC2). Currently, there are no curative therapies for inflammatory and autoimmune diseases, and patients present complex diagnostic, therapeutic, and prognostic problems in daily clinical practice due to their heterogeneous nature. This review focuses on the biology of VIP and VIP receptor signaling, as well as its protective effects as an immunomodulatory factor. Recent progress in improving the stability, selectivity, and effectiveness of VIP/receptors analogues and new routes of administration are highlighted, as well as important advances in their use as biomarkers, contributing to their potential application in precision medicine. On the 50th anniversary of VIP's discovery, this review presents a spectrum of potential clinical benefits applied to inflammatory and autoimmune diseases.