Effect of induction therapy on circulating T-helper 17 and T-regulatory cells in active proliferative lupus nephritis

Pathogenic cellular and molecular mediators in lupus nephritis

Kidney involvement in patients with systemic lupus erythematosus - lupus nephritis (LN) - is one of the most important and common clinical manifestations of this disease and occurs in 40-60% of patients. Current treatment regimens achieve a complete kidney response in only a minority of affected individuals, and 10-15% of patients with LN develop kidney failure, with its attendant morbidity and considerable prognostic implications. Moreover, the medications most often used to treat LN - corticosteroids in combination with immunosuppressive or cytotoxic drugs - are associated with substantial side effects. Advances in proteomics, flow cytometry and RNA sequencing have led to important new insights into immune cells, molecules and mechanistic pathways that are instrumental in the pathogenesis of LN. These insights, together with a renewed focus on the study of human LN kidney tissue, suggest new therapeutic targets that are already being tested in lupus animal models and early-phase clinical trials and, as such, are hoped to eventually lead to meaningful improvements in the care of patients with systemic lupus erythematosus-associated kidney disease.

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.

New insights for regulatory T cell in lupus nephritis

Lupus nephritis (LN) is a complicated autoimmune disease marked by out-of-balance of immunological reactivity and immune tolerance. With the advance of immunotherapy in human disease, regulatory T (Treg) cells serve a crucial function in immune tolerance regulation and are characterized with suppression function as one of the most important research hotspots for autoimmunity diseases. In recent years, Treg cells have shown the robust potential for treatment to autoimmunity diseases like type I diabetic mellitus and rheumatoid arthritis. However, Treg cell therapy is poorly understood for LN patients. This review aims to summarize new insights for Treg-targeting techniques in LN patients. The current data regarding the biology features of Treg cells in LN patients is discussed. The propotion of Treg cells in LN patients have contradictory results regarding the use of different molecular markers. Forkhead box protein 3 (FOXP3) are hallmarks for control function of Treg cells. Treg cells can directly or indirectly target T cells and B cells by playing supressive role. The molecular targets for Treg cells in LN patients includes gene variants, miRNAs, and inflammatory related factors. Based on the current knowledge of Treg cell biology, several therapeutic strategies could be used to treat LN: cell transplantation, low dose IL-2 treatment, drugs target the balance of Treg and type 17 T helper (Th17) cells, and Chinese medicine.

Th17 and Th1 cells in systemic lupus erythematosus with focus on lupus nephritis

Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by T cells imbalance. Indeed, a correlation between levels of Th17 cells and disease activity has been reported. Our work aimed to study the functional association of subpopulations of Th cells and SLE with (lupus nephritis, LN) or without (lupus erythematosus, LE) renal involvement in Tunisian patients through the detection of intracellular cytokines and surface marker expression. The IL23R and RORC mRNA expression levels were evaluated. The level of Th17 and Th1 cells was higher in LE and LN patients compared to healthy controls (HC) (p = 0.007 and p = 0.018, respectively), while Th1/17 cells were increased only in LN patients compared to HC (p = 0.011). However, no significant difference was described in the mRNA expression levels of RORC and IL-23R between SLE and HC. Our findings suggest that the Th1/Th17 differentiation mechanisms are altered in SLE and that this imbalance should have an important influence on the development and severity of the disease.

Th17.1 lymphocytes: emerging players in the orchestra of immune-mediated inflammatory diseases

It is now well established that Th17 lymphocytes associate with myriad immune-mediated inflammatory diseases. Over the past one and a half decades, a subset of Th17 lymphocytes viz. Th17.1 lymphocytes has been identified in pre-clinical and clinical models of inflammatory rheumatic diseases. These lymphocytes secrete IL-17A (signature cytokine of Th17 lymphocytes) as well as IFN-γ (the signature cytokine of Th1 lymphocytes). They express the chemokine markers for Th1 (CXCR3) as well as Th17 (CCR6) lymphocytes. Th17.1 lymphocytes also express the drug efflux protein p-glycoprotein, which associates with resistance to corticosteroids and other immunosuppressive drugs. This narrative review overviews the evidence regarding Th17.1 lymphocytes in different inflammatory rheumatic diseases. It is now recognized that Th17.1 lymphocytes are increased in the synovial fluid of affected joints in rheumatoid arthritis (RA) and associate with poor treatment response to abatacept. Th17.1 lymphocytes from synovial fluid of RA are less responsive to immunosuppression than those from the peripheral blood. In sarcoidosis, Th17.1 lymphocytes are concentrated in mediastinal lymph nodes and alveolar lining. Such Th17.1 lymphocytes in sarcoidosis are the predominant source of IFN-γ in the sarcoid lung. Th17.1 lymphocytes are elevated in lupus and Takayasu arteritis and associate with disease activity. Future studies should evaluate isolated Th17.1 lymphocytes from peripheral blood or sites of pathology such as synovial fluid and assess their modulation with immunosuppressive therapy in vitro. The analysis of gene expression signature of isolated Th17.1 lymphocytes might enable the identification of newer therapeutic strategies specifically targeting these cell populations in inflammatory rheumatic diseases. Key Points • Th17.1 lymphocytes are a subset of Th17 lymphocytes secreting both IFN-γ and IL-17 • Th17.1 lymphocytes drive neutrophilic inflammation, granuloma formation, and corticosteroid resistance • Th17.1 lymphocytes are elevated in rheumatoid arthritis and sarcoidosis at sites of inflammation • Increased circulating Th17.1 lymphocytes have been identified in lupus and Takayasu arteritis and associate with active disease.

Tris DBA Ameliorates Accelerated and Severe Lupus Nephritis in Mice by Activating Regulatory T Cells and Autophagy and Inhibiting the NLRP3 Inflammasome

Tris (dibenzylideneacetone) dipalladium (Tris DBA), a small-molecule palladium complex, has been shown to inhibit cell growth and proliferation in pancreatic cancer, lymphocytic leukemia, and multiple myeloma. In the current study, we examined the therapeutic effects of Tris DBA on glomerular cell proliferation, renal inflammation, and immune cells. Treatment of accelerated and severe lupus nephritis (ASLN) mice with Tris DBA resulted in improved renal function, albuminuria, and pathology, including measurements of glomerular cell proliferation, cellular crescents, neutrophils, fibrinoid necrosis, and tubulointerstitial inflammation in the kidneys as well as scoring for glomerulonephritis activity. The treated ASLN mice also showed significantly decreased glomerular IgG, IgM, and C3 deposits. Furthermore, the compound was able to 1) inhibit bone marrow-derived dendritic cell-mediated T cell functions and reduce serum anti-dsDNA autoantibody levels; 2) differentially regulate autophagy and both the priming and activation signals of the NLRP3 inflammasome; and 3) suppress the phosphorylation of JNK, ERK, and p38 MAPK signaling pathways. Tris DBA improved ASLN in mice through immunoregulation by blunting the MAPK (ERK, JNK)-mediated priming signal of the NLRP3 inflammasome and by regulating the autophagy/NLRP3 inflammasome axis. These results suggest that the pure compound may be a drug candidate for treating the accelerated and deteriorated type of lupus nephritis.

Leptin facilitates the differentiation of Th17 cells from MRL/Mp-Fas lpr lupus mice by activating NLRP3 inflammasome

Both NLRP3 inflammasome and Th17 cells play important roles in the pathogenesis of systemic lupus erythematosus (SLE). Here we tried to investigate whether leptin promotes the differentiation of Th17 cells from lupus mice by activating the NLRP3 inflammasome. Th17 cells induced from MRL/Mp-Fas lpr mice splenocytes under Th17 polarizing condition were treated with leptin at scalar doses during the last 18 h of culture. The mRNA levels of IL-17A, IL-17F, RORγt, IL-1β, IL-18, NLRP3, ASC, and IL-1R1 were detected by quantitative PCR. IL-17A, IL-17F, IL-1β, and IL-18 were tested by ELISA, while the activity of caspase-1 and number of Th17 cells were counted by flow cytometry before/after inhibition of the NLRP3 inflammasome. We found that leptin pushed up the expression of IL-17A, IL-17F, NLRP3, and IL-1β and increased the number of Th17 cells in lupus mice, while the expression of IL-17A, RORγt, and IL-1β and the number of Th17 cells were decreased after inhibition of the NLRP3 inflammasome. Leptin promoted the differentiation of Th17 cells from lupus mice by activating the NLRP3 inflammasome.

Facilitated expansion of Th17 cells in lupus nephritis patients

The objective of this study was to investigate the mechanisms of T helper type 17 (Th17) expansion in lupus nephritis (LN) patients, and to determine whether or not it is associated with impaired function of regulatory T cells (T_reg ). Major effector subsets of peripheral blood CD4⁺ T cells were assessed by flow cytometry in 33 LN patients with different activity of the disease and 19 healthy controls. The percentage of circulating Th17 cells was increased in LN (median = 1·2% of CD4⁺ compared to 0·6% in the control group, P < 0·01), while T_reg cells remained unchanged (12·3 versus 12·1% in controls), resulting in a significantly lower T_reg /Th17 ratio. Th17 expansion in the patient group was not related to LN activity, renal histology or blood and urine inflammatory biomarkers, but has been associated with a higher cumulative dose of cyclophosphamide. T_reg cells in LN displayed mainly effector memory phenotype and expressed higher levels of transforming growth factor (TGF)-β; however, their suppressant activity in lymphocyte proliferation assay was diminished compared to controls (~fourfold, P < 0·05). Co-culture of T_reg and conventional CD4⁺ T cells resulted in marked suppression of the Th1 subset in both of the groups studied, but also in a potent expansion of Th17 cells, which in LN was twofold higher, as in controls (P < 0·05). In conclusion, our results demonstrate that Th17 expansion in LN is not increased during disease exacerbation, but is related to chronic immunosuppressive therapy. This immune signature is probably linked to the abnormal function of T_reg cells, which were less suppressive in LN patients and even facilitated differentiation of Th17 cells.