Interleukin-33 Exacerbates IgA Glomerulonephritis in Transgenic Mice Overexpressing B Cell Activating Factor.

BACKGROUND: The cytokine IL-33 is an activator of innate lymphoid cells 2 (ILC2s) in innate immunity and allergic inflammation. B cell activating factor (BAFF) plays a central role in B cell proliferation and differentiation, and high levels of this protein cause excess antibody production, including IgA. BAFF-transgenic mice overexpress BAFF and spontaneously develop glomerulonephritis that resembles human IgA nephropathy. METHODS: We administered IL-33 or PBS to wild-type and BAFF-transgenic mice. After treating Rag1-deficient mice with IL-33, with or without anti-CD90.2 to preferentially deplete ILC2s, we isolated splenocytes, which were adoptively transferred into BAFF-transgenic mice. RESULTS: BAFF-transgenic mice treated with IL-33 developed more severe kidney dysfunction and proteinuria, glomerular sclerosis, tubulointerstitial damage, and glomerular deposition of IgA and C3. Compared with wild-type mice, BAFF-transgenic mice exhibited increases of CD19+ B cells in spleen and kidney and ILC2s in kidney and intestine, which were further increased by administration of IL-33. Administering IL-33 to wild-type mice had no effect on kidney function or histology, nor did it alter the number of ILC2s in spleen, kidney, or intestine. To understand the role of ILC2s, splenocytes were transferred from IL-33-treated Rag1-deficient mice into BAFF-transgenic mice. Glomerulonephritis and IgA deposition were exacerbated by transfer of IL-33-stimulated Rag1-deficient splenocytes, but not by ILC2 (anti-CD90.2)-depleted splenocytes. Wild-type mice infused with IL-33-treated Rag1-deficient splenocytes showed no change in kidney function or ILC2 numbers or distribution. CONCLUSIONS: IL-33-expanded ILC2s exacerbated IgA glomerulonephritis in a mouse model. These findings indicate that IL-33 and ILC2s warrant evaluation as possible mediators of human IgA nephropathy.

Redirecting TGF-ß Signaling through the ß-Catenin/Foxo Complex Prevents Kidney Fibrosis.

TGF-ß is a key profibrotic factor, but targeting TGF-ß to prevent fibrosis also abolishes its protective anti-inflammatory effects. Here, we investigated the hypothesis that we can redirect TGF-ß signaling by preventing downstream profibrotic interaction of ß-catenin with T cell factor (TCF), thereby enhancing the interaction of ß-catenin with Foxo, a transcription factor that controls differentiation of TGF-ß induced regulatory T cells (iTregs), and thus, enhance anti-inflammatory effects of TGF-ß In iTregs derived from EL4 T cells treated with recombinant human TGF-ß1 (rhTGF-ß1) in vitro, inhibition of ß-catenin/TCF transcription with ICG-001 increased Foxp3 expression, interaction of ß-catenin and Foxo1, binding of Foxo1 to the Foxp3 promoter, and Foxo transcriptional activity. Moreover, the level of ß-catenin expression positively correlated with the level of Foxo1 binding to the Foxp3 promoter and Foxo transcriptional activity. T cell fate mapping in Foxp3gfp Ly5.1/5.2 mice revealed that coadministration of rhTGF-ß1 and ICG-001 further enhanced the expansion of iTregs and natural Tregs observed with rhTGF-ß1 treatment alone. Coadministration of rhTGF-ß1 with ICG-001 also increased the number of Tregs and reduced inflammation and fibrosis in the kidney fibrosis models of unilateral ureteric obstruction and ischemia-reperfusion injury. Notably, ICG-001 prevented the fibrosis in distant organs (lung and liver) caused by rhTGF-ß1. Together, our results show that diversion of ß-catenin from TCF- to Foxo-mediated transcription inhibits the ß-catenin/TCF-mediated profibrotic effects of TGF-ß while enhancing the ß-catenin/Foxo-mediated anti-inflammatory effects. Targeting ß-catenin/Foxo may be a novel therapeutic strategy in the treatment of fibrotic diseases that lead to organ failure.

Development and function of Foxp3(+) regulatory T cells.

Regulatory T cells (Tregs) have been recognized as having a major role in maintaining peripheral tolerance and preventing and limiting autoimmune and chronic inflammatory diseases. Tregs derive from the thymus and also develop peripherally. In this review, we discuss recent progress in our understanding of the basic mechanisms involved in Treg development and function in protecting against autoimmunity in the periphery, including thymic selection, peripheral induction and the many mechanisms of Treg suppression. Specifically in kidney disease, Tregs have been shown to play a role in limiting injury and may potentially have a therapeutic role.

DNA vaccine encoding CD40 targeted to dendritic cells in situ prevents the development of Heymann nephritis in rats.

The CD40-CD154 costimulatory pathway has been shown to be critical for both T- and B-cell activation in autoimmune disease. Here, we assessed the effects of blocking this pathway using CD40 DNA vaccine enhanced by dendritic cell targeting on the development of active Heymann nephritis, a rat model of human membranous nephropathy. DNA vaccination delivers plasmid DNA encoding the target antigen, either alone or in combination with enhancing elements, to induce both humoral and cellular immune responses. To determine whether CD40 DNA vaccine targeting the encoded CD40 directly to dendritic cells would improve the efficacy of the vaccination against self-protein CD40, we utilized a plasmid encoding a single-chain Fv antibody specific for the dendritic cell-restricted antigen-uptake receptor DEC205 (scDEC), the target gene CD40, and the adjuvant tetanus sequence p30. This vaccine plasmid was compared to a control plasmid without scDEC. Rats vaccinated with scDEC-CD40 had significantly less proteinuria and renal injury than did rats receiving scControl-CD40 and were protected from developing Heymann nephritis. Thus, CD40 DNA vaccination targeted to dendritic cells limits the development of Heymann nephritis.

Regulatory T cells participate in CD39-mediated protection from renal injury.

CD39 is an ecto-enzyme that degrades extracellular nucleotides, such as ATP, and is highly expressed on by the vasculature and circulating cells including Foxp3+ regulatory T (Treg) cells. To study the role of purinergic regulation in renal disease, we used the adriamycin nephropathy (AN) mouse model of chronic renal injury, using human CD39-transgenic (hCD39Tg) and wild-type (WT) BALB/c mice. Effects of CD39 expression by Treg cells were assessed in AN by adoptive transfer of CD4(+) CD25(+) and CD4(+) CD25(-) T cells isolated from hCD39Tg and WT mice. hCD39Tg mice were protected from renal injury in AN with decreased urinary protein and serum creatinine, and significantly less renal injury compared with WT mice. While WT CD25(+) and hCD39Tg CD25(-) T cells conferred some protection against AN, hCD39Tg CD25(+) Treg cells offered greater protection. In vitro studies showed direct pro-apoptotic effects of ATP on renal tubular cells. In conclusion, hCD39 expressed by circulating leukocytes and intrinsic renal cells limits innate AN injury. Specifically, CD39 expression by Treg cells contributes to its protective role in renal injury. These findings suggest that extracellular nucleotides mediate AN kidney injury and that CD39, expressed by Treg cells and other cells, is protective in this model.

IL-2/IL-2Ab complexes induce regulatory T cell expansion and protect against proteinuric CKD.

Regulatory T cells (Tregs) help protect against autoimmune renal injury. The use of agonist antibodies and antibody/cytokine combinations to expand Tregs in vivo may have therapeutic potential for renal disease. Here, we investigated the effects of administering IL-2/IL-2Ab complexes in mice with adriamycin nephropathy, a model of proteinuric kidney disease that resembles human focal segmental glomerulosclerosis. Injecting IL-2/IL-2Ab complexes before or, to a lesser extent, after induction of disease promoted expansion of Tregs. Furthermore, administration of this complex was renoprotective, evidenced by improved renal function, maintenance of body weight, less histologic injury, and reduced inflammation. IL-2/IL-2Ab reduced serum IL-6 and renal expression of IL-6 and IL-17 but enhanced expression of IL-10 and Foxp3 in the spleen. In vitro, the addition of IL-2/IL-2Ab complexes induced rapid STAT-5 phosphorylation in CD4 T cells. In summary, these data suggest that inducing the expansion of Tregs by administering IL-2/IL-2Ab complexes is a possible strategy to treat renal disease.

CD8+ regulatory T cells induced by T cell vaccination protect against autoimmune nephritis.

Autoreactive T cells play a pivotal role in the pathogenesis of autoimmune kidney disease. T cell vaccination (TCV) may limit autoimmune disease and induce CD8+ regulatory T cells (Tregs). We used Heymann nephritis (HN), a rat model of human membranous nephritis, to study the effects of TCV on autoimmune kidney disease. We harvested CD4+ T cells from renal tubular antigen (Fx1A) -immunized rats and activated these cells in vitro to express the MHC Class Ib molecule Qa-1. Vaccination of Lewis rats with these autoreactive Fx1A-induced T cells protected against HN, whereas control-primed T cells did not. Rats that underwent TCV had lower levels of proteinuria and serum creatinine and significantly less glomerulosclerosis, tubular damage, and interstitial infiltrates. Furthermore, these rats expressed less IFN-γ and IL-6 in splenocytes, whereas the numbers of Tregs and the expression of Foxp3 were unchanged. In vitro cytotoxicity assays showed CD8+ T cell-mediated elimination of Qa-1-expressing CD4+ T cells. In vivo, TCV abrogated the increase in Qa-1-expressing CXCR5+ TFH cells observed in HN compared with controls. Taken together, these results suggest that TCV protects against autoimmune kidney disease by targeting Qa-1-expressing autoreactive CD4+ cells.

Indirectly Activated Treg Allow Dominant Tolerance to Murine Skin-grafts Across an MHC Class I Mismatch After a Single Donor-specific Transfusion.

BACKGROUND: Tolerance induced in stringent animal transplant models using donor-specific transfusions (DST) has previously required additional immunological manipulation. Here, we demonstrate a dominant skin-allograft tolerance model induced by a single DST across an major histocompatibility class I mismatch in an unmanipulated B6 host. METHODS: C57BL/6 (H-2) (B6) mice were injected intravenously with splenocytes from B6.C.H-2 (H-2k) (bm1) or F1 (B6 × bm1) mice before skin transplantation. Mice were transplanted 7 days postinjection with donor (bm1 or F1) and third-party B10.BR (H-2) skin grafts. RESULTS: B6 hosts acutely rejected skin grafts from B6.C.H-2 (bm1) and F1 (B6 × bm1) mice. A single transfusion of F1 splenocytes into B6 mice without any additional immune modulation led to permanent acceptance of F1 skin grafts. This graft acceptance was associated with persistence of donor cells long-term in vivo. The more rapid removal of DST bm1 cells than F1 cells was reduced by natural killer-cell depletion. Tolerant grafts survived an in vivo challenge with naive splenocytes. Both CD4CD25 and CD4CD25 T cells from F1 DST treated B6 mice suppressed alloproliferation in vitro. Tolerance was associated with expansion of peripheral Foxp3CD4CD25 regulatory T cells (Treg) and increased forkhead box P3 (Foxp3) expression in tolerant grafts. In tolerant mice, Foxp3 Treg arises from the proliferation of indirectly activated natural Foxp3 Treg (nTreg) and depletion of Foxp3 Treg abrogates skin-graft tolerance. CONCLUSIONS: This study demonstrates that the persistence of transfused semiallogeneic donor cells mismatched at major histocompatibility class I can enhance tolerance to subsequent skin allografts through indirectly expanded nTreg leading to dominant tolerance without additional immunological manipulation.

DEC205-DC targeted DNA vaccine against CX3CR1 protects against atherogenesis in mice.

Studies disrupting the chemokine pathway CX3CL1 (fractalkine)/ CX3CR1 have shown decreased atherosclerosis in animal models but the techniques used to interrupt the pathway have not been easily translatable into human trials. DNA vaccination potentially overcomes the translational difficulties. We evaluated the effect of a DNA vaccine, targeted to CX3CR1, on atherosclerosis in a murine model and examined possible mechanisms of action. DNA vaccination against CX3CR1, enhanced by dendritic cell targeting using DEC-205 single chain variable region fragment (scFv), was performed in 8 week old ApoE-/- mice, fed a normal chow diet. High levels of anti-CX3CR1 antibodies were induced in vaccinated mice. There were no apparent adverse reactions to the vaccine. Arterial vessels of 34 week old mice were examined histologically for atherosclerotic plaque size, macrophage infiltration, smooth muscle cell infiltration and lipid deposition. Vaccinated mice had significantly reduced atherosclerotic plaque in the brachiocephalic artery. There was less macrophage infiltration but no significant change to the macrophage phenotype in the plaques. There was less lipid deposition in the lesions, but there was no effect on smooth muscle cell migration. Targeted DNA vaccination to CX3CR1 was well tolerated, induced a strong immune response and resulted in attenuated atherosclerotic lesions with reduced macrophage infiltration. DNA vaccination against chemokine pathways potentially offers a potential therapeutic option for the treatment of atherosclerosis.

Transforming growth factor beta (TGFß) plays a crucial role in prolonging allograft survival in an allodepletion ("pruning") skin transplant model.

Adoptive cell therapies involving cell manipulation to achieve tolerance are increasingly being studied in animal models and in human trials. We have demonstrated that the specific removal of allo-stimulated dividing cells (or "pruning") promotes long-term allograft survival across a major MHC mismatch in transplant models including skin, heart and islet transplants. In this study, we examine the role of transforming growth factor beta (TGFß), an important regulatory cytokine, on allograft survival in our allodepletion or "pruning" skin transplant model. Increased proliferation of CD4(+) T cells was observed following allo-stimulation of BALB/c spleen cells (labeled with CFSE) in the presence of the regulatory cytokines TGFß and (interleukin-2) IL-2 in a mixed lymphocyte culture (MLC). Expression of the regulatory gene forkhead box-3 (FoxP3) was increased in both the allo-stimulated non-dividing (ND) (CFSE(high)) and dividing (D) (CFSE(low)) CD4(+) T cell populations, with the highest expression found in the D CD4(+) T cell population. Mice reconstituted with allo-stimulated ND CD4(+) T cells following TGFß/IL-2 stimulation showed prolonged allograft survival, similar to previous data. Significantly, TGFß/IL-2 stimulation prevented acute rejection of allografts across a major MHC mismatch in the presence of highly activated allo-stimulated D CD4(+) T cells. Blockade of TGFß promoted rejection of allografts even following depletion of allo-stimulated D CD4(+) T cells. These studies support a crucial role for TGFß in the survival of allografts and shows that regulatory cytokines TGFß/IL2 can delay the rejection of allografts, even in the presence of highly activated alloreactive T cells.

Regulatory T cells require renal antigen recognition through the TCR to protect against injury in nephritis.

Regulatory T cells (Treg) are important for maintaining immune homeostasis. Adoptive transfer of Tregs is protective in renal disease models in both immunocompetent and immunodeficient mice. However the involvement of TCR recognition of renal antigens remains to be clarified. To address this question, we made use of Tregs from the DO11.10 mouse (a TCR transgenic (Tg) mouse), that recognise the non-murine antigen Ovalbumin (OVA) and therefore are not activated by renal antigens. DO11.10 Tregs were assessed functionally in vitro and demonstrated equivalent suppression to WT BALB/c Tregs. Adriamycin Nephropathy (AN) was induced in mice which had been transfused with CD4+CD25+Tregs isolated from DO11.10 or BALB/c mice. To eliminate the memory/activation state as a cause of differences in activity, the protective capacity of DO11.10 Tregs pre-activated with OVA in vivo was assessed. Transfer of WT BALB/c Tregs significantly attenuated the development of AN with less glomerulosclerosis, tubular atrophy and macrophage infiltration as compared to AN mice without Treg transfer. However, mice receiving either naïve or pre-activated DO11.10 Tregs were not protected from AN. The lack of protection by DO11.10 Tregs was not due to failure to traffic to the affected kidney. These results suggest that antigen recognition in the kidney is important for Treg protection against injury.

Daedalic DNA vaccination against self antigens as a treatment for chronic kidney disease.

Chronic kidney disease (CKD) is a major cause of death and morbidity in Australia and worldwide. DNA vaccination has been used for targeting foreign antigens to induce immune responses and prevent autoimmune disease, viral infection and cancer. However, the use of DNA vaccination has been restricted by a limited ability to induce strong immune responses, especially against self-antigens which are limited by mechanisms of self-tolerance. Furthermore, there have been few studies on the potential of DNA vaccination in chronic inflammatory diseases, including CKD. We have established strategies of DNA vaccination targeting specific self-antigens in the immune system including co-stimulatory pathways, T cell receptors and chemokine molecules, which have been effective in protecting against the development of CKD in a variety of animal models. In particular, we find that the efficacy of DNA vaccination is improved by dendritic cell (DC) targeting and can protect against animal models of autoimmune nephritis mimicking human membranous nephropathy. In this review, we summarize several approaches that have been tested to improve the efficacy of DNA vaccination in CKD models, including enhanced DNA vaccine delivery methods, DNA vaccine modifications and new molecular targets for DNA vaccination. Finally, we discuss the specific application of DNA vaccination for preventing and treating CKD.

DEC205-DC targeted DNA vaccines to CX3CR1 and CCL2 are potent and limit macrophage migration.

Monocytes utilise a variety of chemokines to traffic to atherosclerotic plaques. CX3C chemokine ligand 1 (CX3CL1 & Fractalkine) and its receptor CX3CR1 and monocyte chemoattractant protein 1 (CCL2) have been identified as chemokines/receptors that have an important role in the migration and recruitment of monocytes during the pathogenesis of several inflammatory diseases including atherosclerosis. DNA vectors containing single chain variable region fragment (scFv) for DC-targeted receptor DEC205 were cloned with mouse CX3CR1 and CCL2 genes respectively, and vaccinated into C57/BL6 mice weekly for 3 weeks. Induced anti-CX3CR1 and anti-CCL2 in vaccinated mice was examined by ELISA and Western Blot analysis, while the cellular response was examined by ELISPOT. The inhibition of chemotaxis of J774 macrophages to Py-4-1 endothelial cells was examined by in vitro transwell migration assay using serum collected from vaccinated mice. All vaccinated mice generated anti-CX3CR1 and anti-CCL2 Ab and cellular response by 8 weeks after DNA vaccination. Macrophage migration towards TNF-α activated endothelial cells was significantly inhibited by serum containing both anti-CX3CR1 or anti-CCL2 Ab from vaccinated mice. These results demonstrate that DC-targeting of DNA vaccines to self-antigens generates functional immune responses which can inhibit specific key chemotactic targets. This suggests a potential therapeutic role for chemokine/receptor DNA vaccination in atherosclerosis, where chemotaxis has a pivotal role in the inflammatory process.

Regulatory T cells in renal disease.

Regulatory T cells (Tregs) have a key role in immune homeostasis and in suppressing unwanted inflammatory responses toward self-antigens. Tregs have been implicated in the control of initial activation events, and play roles in limiting proliferation, differentiation and effector functions of T helper cells. However, the activities of Tregs in the development and progression of kidney disease are not fully elucidated. We have demonstrated the potency of Tregs in animal models of kidney disease. In this review, we summarise mechanistic information from rodent models on the roles of Tregs in glomerular immunopathology and discuss the function of Tregs in diverse kidney diseases. Further studies of Tregs should provide important insights into designing of therapeutic strategies to prevent human kidney disease.

Depletion of gammadelta T cells exacerbates murine adriamycin nephropathy.

It has been reported that the presence of gammadelta T cells in kidney is associated with kidney damage in human IgA nephropathy and in rat models of chronic renal injury, including Adriamycin nephropathy (AN), but the functional role of gammadelta T cells in this setting is unknown. This study examined the functional role of gammadelta T cells in tissue injury in a murine model of AN. Murine AN was induced in BALB/c mice by a single injection of Adriamycin. gammadelta T cells as a proportion of CD3(+) T cells were significantly increased in AN kidneys (16.8 +/- 3.9%) but not in lymph nodes (1.3 +/- 0.8%; P < 0.001). The proportion of gammadelta T cells in AN kidney correlated positively with serum creatinine and glomerular sclerosis. The Vgammadelta T cell receptor (TCR) repertoire in kidney showed expansion of a subset of cells that expressed Vgamma6/Vdelta1 genes and that used canonical TCR Vgamma6/Vdelta1 sequences in the CDR3 region of the TCR. gammadelta T cells that were sorted from the kidneys expressed TGF-beta but not IL-4, IL-10, or IFN-gamma. gammadelta T cells also expressed the activating receptor NKG2D and the NKG2D adaptor molecule DAP12. RAE-1, a ligand of NKG2D, was upregulated in AN kidney. Depletion of gammadelta T cells using anti-TCR gammadelta antibody resulted in worsening of serum creatinine, glomerulosclerosis, and interstitial inflammation. These studies indicate the involvement of the gammadelta T cell in innate recognition and regulation of inflammation in AN.

Foxp3-transduced polyclonal regulatory T cells protect against chronic renal injury from adriamycin.

Chronic proteinuric renal injury is a major cause of ESRD. Adriamycin nephropathy is a murine model of chronic proteinuric renal disease whereby chemical injury is followed by immune and structural changes that mimic human disease. Foxp3 is a gene that induces a regulatory T cell (Treg) phenotype. It was hypothesized that Foxp3-transduced Treg could protect against renal injury in Adriamycin nephropathy. CD4+ T cells were transduced with either a Foxp3-containing retrovirus or a control retrovirus. Foxp3-transduced T cells had a regulatory phenotype by functional and phenotypic assays. Adoptive transfer of Foxp3-transduced T cells protected against renal injury. Urinary protein excretion and serum creatinine were reduced (P<0.05), and there was significantly less glomerulosclerosis, tubular damage, and interstitial infiltrates (P<0.01). It is concluded that Foxp3-transduced Treg cells may have a therapeutic role in protecting against immune injury and disease progression in chronic proteinuric renal disease.

"Pruning" of alloreactive CD4+ T cells using 5- (and 6-)carboxyfluorescein diacetate succinimidyl ester prolongs skin allograft survival.

Removal of alloreactive cells by either thymic deletion or deletion/anergy in the periphery is regarded as crucial to the development of tolerance. Dyes, such as CFSE, that allow monitoring of cell division suggest that in vitro proliferation could be a used as a way of "pruning" alloreactive cells while retaining a normal immune repertoire with retention of memory to previously encountered pathogens. This would overcome the problems occurring as a result of therapies that use massive depletion of T cells to allow acceptance of organ transplants or bone marrow grafts. We therefore used a skin graft model of CD4-mediated T cell rejection across a major H-2 mismatch (C57BL/6 (H-2(b)) to BALB/c (H-2(d)) mice) to evaluate whether nondividing CD4(+) T cells derived from a mixed lymphocyte culture would exhibit tolerance to a skin graft from the initial stimulator strain. We demonstrate that selective removal of dividing alloreactive CD4(+) T cells resulted in marked specific prolongation of allogeneic skin graft survival, and that the nondividing CD4(+) T cells retained a broad TCR repertoire and the ability to maintain memory. This novel way of depleting alloreactive T cells may serve as a useful strategy in combination with other mechanisms to achieve transplant tolerance.