Recombinant interleukin-17A Research Articles

Bidirectional interaction between IL and 17A/IL-17RA pathway dysregulation and α-synuclein in the pathogenesis of Parkinson’s disease

Parkinson’s disease (PD) pathogenesis is characterized by α-synuclein (α-syn) pathology, which is influenced by various factors such as neuroinflammation and senescence. Increasing evidence has suggested a pivotal role for Interleukin-17A(IL-17A) and Interleukin-17 Receptor A (IL-17RA) in PD, yet the trigger and impact of IL-17A/IL-17RA activation in PD remains elusive. This study observed an age-related increase in IL-17A and IL-17RA in the human central nervous system, accompanied by increased α-syn and senescence biomarkers. Interestingly, both levels of IL-17A and IL-17RA in PD patients were significantly elevated compared to age-matched controls, wherein the IL-17A was mainly present in neurons. This abnormal neuronal IL-17A activation in the PD brain was recapitulated in α-syn mouse models. Correspondingly, administration of recombinant IL-17A exacerbated pathological α-syn in both neuron and mouse models. Furthermore, IL-17A/IL-17RA pathway interventions via blocking antibody or shRNA-mediated knockdown can mitigate the effects of pathological α-syn. This study reveals an interplay between dysregulation of the IL-17A/IL-17RA pathway and α-syn, suggesting that regulating the IL-17A/IL-17RA pathway could modify PD progression by disrupting the detrimental cycle.

Pre-treatment with chicken IL-17A secreted by bioengineered LAB vector protects chicken embryo fibroblasts against Influenza Type A Virus (IAV) infection

The recent advances in our understanding of the host factors in orchestrating qualitatively different immune responses against influenza Type A virus (IAV) have changed the perception of conventional approaches for controlling avian influenza virus (AIV) infection in chickens. Given that infection-induced pathogenicity and replication of influenza virus largely rely on regulating host immune responses, immunoregulatory cytokine profiles often determine the disease outcomes. However, in contrast to the function of other inflammatory cytokines, interleukin-17A (IL-17A) has been described as a ‘double-edged sword’, indicating that in addition to antiviral host responses, IL-17A has a distinct role in promoting viral infection. Therefore, in the present study, we investigated the chicken IL-17A mediated antiviral immune effects on IAVs infection in primary chicken embryo fibroblasts cells (CEFs). To this end, we first bioengineered a food-grade Lactic Acid Producing Bacteria (LAB), Lactococcus lactis (L. lactis), secreting bioactive recombinant chicken IL-17A (sChIL-17A). Next, the functionality of sChIL-17A was confirmed by transcriptional upregulation of several genes associated with antiviral host responses, including granulocyte-monocyte colony-stimulating factor (GM-CSF) (CSF3 in the chickens), interleukin-6 (IL-6), interferon-α (IFN-α), -β and -γ genes in primary CEFs cells. Consistent with our hypothesis that such a pro-inflammatory state may translate to immunoprotection against IAVs infection, we observed that sChIL-17A pre-treatment could significantly limit the viral replication and protect the primary CEFs cells against two heterotypic IAVs such as A/turkey/Wisconsin/1/1966(H9N2) and A/PR/8/1934(H1N1). Together, the data presented in this work suggest that exogenous application of sChIL-17A secreted by modified LAB vector may represent an alternative strategy for improving antiviral immunity against avian influenza virus infection in chickens.

Recombinant bovine IL17A acts as an adjuvant for bovine herpesvirus vaccine

The Bovine herpes virus type 5 glycoprotein D (gD) is essential for viral penetration into host permissive cells. The Herpes virus gD glycoprotein has been used for bovine immunization, being efficient in reduction of viral replication, shedding and clinical signs, however sterilizing immunity is still not achieved. Recombinant subunit vaccines are, in general, poorly immunogenic requiring additional adjuvant components. Interleukin 17A (IL17A) is a pro-inflammatory cytokine produced by T helper 17 cells that mediate mucosal immunity. IL17 production during vaccine-induced immunity is a requirement for mucosal protection to several agents. In this study, we investigated the potential of a recombinant IL17A to act as an adjuvant for a recombinant BoHV-5 glycoprotein D vaccine in cattle. Three cattle groups were divided as: group 1) rgD5 + alumen + rIL-17A; 2) rgD5 + alumen; and 3) PBS + alumen. The cattle (3 per group) received two doses of their respective vaccines at an interval of 21 days. The group that received rIL17 in its vaccine formulation at the 7th day after the prime immunization had significant higher levels of specific rgD-IgG than the alumen group. Addition of rIL17 also led to a significant fold increase in specific anti-rgD IgG and neutralizing antibodies to the virus, respectively, when compared with the alumen group. Cells stimulated with rIL17A responded with IL17 transcription, as well IL2, IL4, IL10, IL15, Bcl6 and CXCR5. Our findings suggest that the rIL17A has adjuvant potential for use in vaccines against BoHV-5 as well as potentially other pathogens of cattle.

Interleukin-17A Facilitates Chikungunya Virus Infection by Inhibiting IFN-α2 Expression.

Interferons (IFNs) are the key components of innate immunity and are crucial for host defense against viral infections. Here, we report a novel role of interleukin-17A (IL-17A) in inhibiting IFN-α2 expression thus promoting chikungunya virus (CHIKV) infection. CHIKV infected IL-17A deficient (Il17a−/−) mice expressed a higher level of IFN-α2 and developed diminished viremia and milder footpad swelling in comparison to wild-type (WT) control mice, which was also recapitulated in IL-17A receptor-deficient (Il17ra−/−) mice. Interestingly, IL-17A selectively blocked IFN-α2 production during CHIKV, but not West Nile virus (WNV) or Zika virus (ZIKV), infections. Recombinant IL-17A treatment inhibited CHIKV-induced IFN-α2 expression and enhanced CHIKV replication in both human and mouse cells. We further found that IL-17A inhibited IFN-α2 production by modulating the expression of Interferon Regulatory Factor-5 (IRF-5), IRF-7, IFN-stimulated gene 49 (ISG-49), and Mx1 expression during CHIKV infection. Neutralization of IL-17A in vitro leads to the increase of the expression of these antiviral molecules and decrease of CHIKV replication. Collectively, these results suggest a novel function of IL-17A in inhibiting IFN-α2–mediated antiviral responses during CHIKV infection, which may have broad implications in viral infections and other inflammatory diseases.

Interleukin 17A deficiency alleviates fluoride-induced testicular injury by inhibiting the immune response and apoptosis

The reproductive toxicity of fluoride (F) has been verified by various epidemiological and experimental studies. Our previous work suggested that the interleukin 17A (IL-17A) is involved in the testicular damage induced by excessive F exposure. In this study, we further investigated the role of IL-17A in F-induced testicular injury. Wild type (WT) and IL-17A knockout (IL-17A-/-) mice were exposed to 0, 25, 50, or 100 mg/L sodium fluoride (NaF) for 90 days. We found that exposure to excessive F levels caused testicular damage, decreased semen quality, negatively affected testicular morphology, and increased the inflammatory response. Specifically, excessive F intake increased the expression levels of IL-17A in the testis and increased the protein levels of Act1, NF-κB, IL-17R, C/EBP-α, and TRAF6 in the IL-17A signaling pathway. The increase in IL-17A expression corresponded to increases expression of IL-17R, IL-6, IL-23, IL-1β, TGF-β and TNF-α as assessed by RT-PCR and ELISA assays. Remarkably, IL-17A knockout in mice ameliorated the effects of F on testicular damage, semen quality, testicular morphology, and the immune response. Additionally, we found the in vitro exposure of Leydig cells to NaF and recombinant IL-17A led to abnormal apoptosis and a decrease in testosterone secretion. Our findings prove that IL-17A plays a key role in the exacerbation of testicular injuries in F-exposed mice, and that IL-17A deficiency can alleviate F-induced injury by inhibiting the immune response and apoptosis in the testis. These data suggest that targeting IL-17A may be a useful therapeutic strategy for treating F-mediated toxicity in the testis.

Long-term PM2.5 exposure increases the risk of non-small cell lung cancer (NSCLC) progression by enhancing interleukin-17a (IL-17a)-regulated proliferation and metastasis.

PM2.5 is a class of airborne particles and droplets with sustained high levels in many developing countries. Epidemiological studies have indicated that PM2.5 is closely associated with the increased morbidity and mortality of lung cancer in the world. Unfortunately, the effects of PM2.5 on lung cancer are largely unknown. In the present study, we attempted to explore the role of PM2.5 in the etiology of NSCLC. Here, we found that long-term PM2.5 exposure led to significant pulmonary injury. Epithelial-mesenchymal transition (EMT) and cancer stem cells (CSC) properties were highly induced by PM2.5 exposure. EMT was evidenced by the significant up-regulation of MMP2, MMP9, TGF-β1, α-SMA, Fibronectin and Vimentin. Lung cancer progression was associated with the increased expression of Kras, c-Myc, breast cancer resistance protein BCRP (ABCG2), OCT4, SOX2 and Aldh1a1, but the decreased expression of p53 and PTEN. Importantly, mice with IL-17a knockout (IL-17a-/-) showed significantly alleviated lung injury and CSC properties following PM2.5 exposure. Also, IL-17a-/--attenuated tumor growth was recovered in PM2.5-exposed mice injected with recombinant mouse IL-17a, accompanied with significantly restored lung metastasis. Taken together, these data revealed that PM2.5 could promote the progression of lung cancer by enhancing the proliferation and metastasis through IL-17a signaling.

High levels of plasma interleukin-17A are associated with severe neurological sequelae in Langerhans cell histiocytosis

ObjectiveLangerhans cell histiocytosis (LCH) is a granulomatous inflammatory myeloid neoplasia associated with a cytokine storm in both serum and lesions. Increased levels of plasma interleukin-17A (IL-17A) in LCH patients have been reported, but this finding was not confirmed in all studies. Neurodegeneration is a devastating complication of LCH (ND-LCH). We aimed to revisit the issue of plasma IL-17A levels in LCH, by using a larger number of patients, and also to investigate the relationship between IL-17A and LCH sequelae, especially ND-LCH. MethodsPlasma samples from 68 LCH patients and 127 controls were analyzed for IL-17A levels by two ELISAs with different anti-IL-17A capture antibodies: either polyclonal or neutralizing monoclonal antibodies in 17polyAb-ELISA or 17mAb-ELISA, respectively. ResultsBoth ELISAs had a similar capacity to specifically detect recombinant or native human IL-17A, as well as plasma IL-17A from LCH patients. We confirmed the finding of higher levels of plasma IL-17A in LCH patients compared to controls (p < 0.0001). The association of IL-17A with LCH was independent of the ELISA used, and of gender, age, disease class activity, and pattern of tissue-organ involvement (single-system versus multi-system). ROC analyses (p < 0.0001) allow to discriminate LCH patients from the control group, supporting the notion that IL-17A may be a potential biomarker for LCH. More interestingly, high IL-17A levels were significantly associated with LCH patients having sequelae, with the highest plasma levels in patients with ND-LCH (p < 0.0001). ConclusionThe association between high levels of IL-17A and LCH was confirmed. IL-17A may be associated with ND-LCH development. This might have therapeutic implications, offering a novel target for precision therapy of ND-LCH.

Effects of skin γδ T lymphocytes on wound healing of mice through regulating proliferation and differentiation of mice epidermal cells

Effects of skin γδ T lymphocytes on wound healing of mice through regulating proliferation and differentiation of mice epidermal cells

IL-17A contributes to perioperative neurocognitive disorders through blood-brain barrier disruption in aged mice

BackgroundPerioperative neurocognitive disorders (PND) occur frequently after surgery, especially in aged patients. Surgery-induced neuroinflammation and blood-brain barrier (BBB) dysfunction play a crucial role in the pathogenesis of PND. Interleukin-17A (IL-17A) increases after surgical stress and will be involved in BBB dysfunction. However, the effect of IL-17A on BBB function during PND remains poorly understood.MethodsMale wild-type C57BL/6J mice (15 months old) received tibial fracture surgery and fixation to establish the PND model. All the mice were injected intraperitoneally with an IL-17A-neutralizing antibody (Abs) or isotype-control Abs 30 min before tibial fracture surgery. Animal behaviour tests conducted 24 h after surgery included the contextual fear conditioning and Y maze tests. Serum and hippocampus IL-17A levels and hippocampus IL-6 and IL-1β levels were detected by ELISA. BBB function was detected by Evans blue (EB) test. Hippocampus matrix metalloproteinase-2 (MMP-2)- and MMP-9-positive cells were detected by immunohistochemistry. Hippocampus albumin, occludin, claudin-5 and IL-17A receptors were detected by Western blot. For the in vitro experiment, bEnd.3 cells were incubated with IL-17A. Cell IL-17A receptors were detected by immunofluorescence. Cellular MMP-2, MMP-9, occludin, and claudin-5 were detected by Western blot.ResultsTibial fracture surgery promoted memory impairment, increased levels of IL-17A and IL-17A receptors, inflammatory factor production and BBB dysfunction. IL-17A Abs inhibited this effect, including improving memory function, decreasing inflammatory factor production and alleviating BBB disruption, indicated by decreased tight junctions (TJs) and increased MMPs after surgery. The in vitro study suggested that recombinant IL-17A could upregulate the expression of IL-17A receptors, decrease TJs and increase the level of MMPs in bEnd.3 cells.ConclusionsOur results suggested that IL-17A-promoted BBB disruption might play an important role in the pathogenesis of PND.

Interleukin-17A promotes osteogenic differentiation by increasing OPG/RANKL ratio in stem cells from human exfoliated deciduous teeth (SHED).

Stem cells derived from human exfoliated deciduous teeth (SHED) represent a promising cell source for bone tissue regeneration. This study evaluated the effects of interleukin-17A (IL-17A) on the osteogenic differentiation of SHED. SHED were cultured in complete alpha minimum essential medium supplemented with osteoinducing reagents and treated with recombinant IL-17A. The cells were quantitatively analysed for proliferative activity by MTS assay, cell markers expression, and apoptotic activity by flow cytometry. For osteogenic differentiation, alkaline phosphatase (ALP) activity was quantified; mineralization assays were carried out using von Kossa and Alizarin red, and expression of osteogenic markers were analysed by real-time polymerase chain reaction and Western blot. The results showed that treatment with IL-17A increased proliferative activity in a dose-dependent manner, but reduced the expression of stem cell markers (c-Myc and Nanog) as the days progressed. IL-17A induced osteogenic differentiation in SHED as evidenced by high ALP activity, increased matrix mineralization, and upregulation of the mRNA expression of the osteogenic markers ALP, alpha 1 type 1 collagen (Col1A1), runt-related transcription factor 2 (RUNX2), osteopontin (OPN), osteocalcin (OCN), and osteoprotegerin (OPG) but downregulation of receptor activator of nuclear factor κB ligand (RANKL) as well as altering the OPG/RANKL ratio. Findings from our study indicate that IL-17A enhances proliferation and osteogenic differentiation of SHED by regulating OPG/RANKL mechanism thus suggests therapeutic potential of IL-17A in bone regeneration.

Interleukin-17A-Deficient Mice Are Highly Susceptible to Toxoplasma gondii Infection Due to Excessively Induced T. gondii HSP70 and Interferon Gamma Production.

Interleukin17A (IL-17A) is known to be involved in the host defense against pathogens and the pathogenesis of autoimmune diseases. Previously, we showed that excessive amounts of interferon gamma (IFN-γ) play an important role in the pathogenesis of the lethal effects of Toxoplasma gondii by inducing anaphylactic responses. In the study described in this report, we examined the effects of IL-17A deficiency on murine host defense against oral T. gondii infection. IL-17A-deficient C57BL/6 (B6) mice exhibited higher rates of mortality than wild-type (WT) mice during the acute phase of T. gondii infection. CD4+ T cells in the mesenteric lymph nodes (mLNs) and ileum of T. gondii-infected IL-17A-deficient mice produced higher levels of IFN-γ than did those of WT mice. In addition, the level of T. gondii HSP70 (T.gHSP70) expression was also significantly increased in the ileum, mLNs, liver, and spleen of infected IL-17A-deficient mice compared with that in WT mice. These elevated levels of expression of T.gHSP70 and IFN-γ in infected IL-17A-deficient mice were presumably linked to the IL-17A defect since they decreased to WT levels after treatment with recombinant IL-17A. Furthermore, IL-17A-deficient mice were highly susceptible to the anaphylactic effect of T.gHSP70, and the survival of IL-17A-deficient mice during the acute phase was improved by treatment with an anti-T.gHSP70 monoclonal antibody. These results suggest that IL-17A plays an important role in host survival against T. gondii infection by protecting the host from an anaphylactic reaction via the downregulation of T.gHSP70 and IFN-γ production.

Interleukin-17A Promotes CD8+ T Cell Cytotoxicity To Facilitate West Nile Virus Clearance.

Interleukin-17A (IL-17A) and CD8+ T cells regulate diverse immune functions in microbial infections, malignancies, and autoimmune diseases. IL-17A is a proinflammatory cytokine produced by diverse cell types, while CD8+ T cells (known as cytotoxic T cells) are major cells that provide immunity against intracellular pathogens. Previous studies have demonstrated a crucial role of CD8+ T cells in recovery from West Nile virus (WNV) infection. However, the role of IL-17A during WNV infection remains unclear. Here, we demonstrate that IL-17A protects mice from lethal WNV infection by promoting CD8+ T cell-mediated clearance of WNV. In addition, treatment of WNV-infected mice with recombinant IL-17A reduces the viral burden and increases survival of mice, suggesting a potential therapeutic. This novel IL-17A-CD8+ T cell axis may also have broad implications for immunity to other microbial infections and cancers, where CD8+ T cell functions are crucial.

IL-17A promotes neutrophilic inflammation and disturbs acute wound healing in skin.

In the wound healing process, neutrophils are the first inflammatory cells to move to the wound tissues. They sterilize wounds by killing microbes, and they stimulate other immune cells to protect the host from infection. In contrast, neutrophil-derived proteases cause damage to host tissues, so neutrophils play dual opposite roles in wound healing. Interleukin-17A (IL-17A) is a proinflammatory cytokine that promotes the recruitment of these cells. The role of this cytokine in the wound healing process is not fully clarified. In the present study, therefore, we examined how defect in IL-17A production affected the wound healing in skin. IL-17A-knockout (KO) mice showed promoted wound closure, myofibroblast differentiation and collagen deposition and decreased the neutrophil accumulation compared with wild-type (WT) mice. In contrast, the administration of recombinant IL-17A led to delayed wound closure, low collagen deposition and accelerated neutrophilic accumulation. In addition, the treatment of IL-17A-administered mice with a neutrophil elastase inhibitor improved the wound repair to the same level as that of WT mice. These results indicated that IL-17A hampered the wound healing process and suggested that neutrophilic inflammation caused by IL-17A may be associated with impaired wound healing in skin.

The dendritic cell-T helper 17-macrophage axis controls cholangiocyte injury and disease progression in murine and human biliary atresia.

These findings identify the dendritic cell-T helper 17-macrophage axis as a target for the development of strategies to block progression of intrahepatic bile duct injury in patients with BA. (Hepatology 2017;65:174-188).

Knockout of microRNA-155 ameliorates the Th1/Th17 immune response and tissue injury in chronic rejection

MicroRNAs (miRNAs) are integral for maintaining immune homeostasis and self-tolerance. The influence of miRNAs on T-cell differentiation and plasticity are critical in the development of chronic rejection of transplanted hearts. In this study, we sought to determine whether the knockout of miR-155 affects the development of cardiac allograft vasculopathy (CAV) in a murine model. miRNA microarray and quantitative polymerase chain reaction (qPCR) analyses were performed for allograft neointimal lesion samples in chronic rejection. A model of heterotopic murine heart transplantation (bm12 to miR-155+/+ or miR-155-/- mice) was then used to analyze allograft survival, histology, mRNA expression and T-cell sub-populations in spleens. The accelerated experiments were performed by intraperitoneal injection of either recombinant interleukin-17A or phosphate-buffered saline (PBS) after heart transplantation. For the competitive transfer experiments, CD4+ splenocytes from wild-type (WT) or miR-155-/- mice were mixed and injected into Rag1-/- mice, and cardiac transplantation was performed after 24 hours. The differentiation of T-helper subsets (Th1/Th17/iTreg) was investigated in vitro. miR-155-/- mice showed resistance to cardiac rejection along with weakened T-cell-mediated inflammation, especially for Th17 cells. Recombinant IL-17A could restore this relieved injury. The competitive experiments implied that miR-155 plays a vital role in the stability of the Th17 phenotype. In vitro, we also demonstrated that miR-155-/- mice exhibit a defect in Th17 differentiation. miR-155 regulates Th1/Th17-related inflammation in chronic cardiac rejection and may be a potential therapeutic target to attenuate cardiac allograft rejection. Despite advancements in immunosuppressive therapy, the immunologic mechanisms responsible for allograft rejection remain an important issue for both clinicians and researchers. Allograft rejection is a T-cell-dependent phenomenon and is critically dependent on inflammation mediated by CD4+ Th subsets, including Th1, Th2, Th17, Th9 and regulatory T (Treg) cells.

IFN-γ induction by neutrophil-derived IL-17A homodimer augments pulmonary antibacterial defense.

The role of interleukin-17A (IL-17A) in host defense against Legionella pneumophila remains elusive. To address this issue, we used Il17a(-/-), Il17f(-/-), and Il17a/Il17f(-/-) mice on a C57Bl/6 (non-permissive) background and IL-17 neutralizing Abs in mice on an A/J (permissive) background. Higher bacterial (L. pneumophila) counts in the lung and blood along with reduced neutrophil recruitment were detected in Il17a(-/-), but not Il17f(-/-), mice. We found that neutrophils produce IL-17A homodimer (IL-17A) during L. pneumophila infection, and hematopoietic cell-derived IL-17A is known to be important for bacterial clearance. Thus, intratracheal administration of wild-type neutrophils or recombinant IL-17A restored bacterial clearance and neutrophil recruitment in Il17a(-/-) mice. Furthermore, neutrophil-depleted Rag2(-/-) and Rag2/Il-2rγ(-/-) mice exhibited increased bacterial burden, reduced neutrophil influx and IL-17A production in the lung. Recombinant IFN-γ administration in Il17a(-/-) mice augmented bacterial elimination, whereas IL-17A administration in Ifnγ(-/-) mice did not augment bacterial clearance. IFN-γ is produced by T cells, but not neutrophils or macrophages, suggesting that neutrophil-derived IL-17A induces IFN-γ in a paracrine fashion. Human pneumonic lungs and human neutrophils challenged with L. pneumophila exhibited increased numbers of IL-17A producing cells. These findings display a novel function of neutrophil-derived IL-17A in antibacterial defense via the induction of IFN-γ in a paracrine manner.

Orthodontic treatment mediates dental pulp microenvironment via IL17A

ObjectiveOrthodontic treatment induces dental tissue remodeling; however, dental pulp stem cell (DPSC)-mediated pulp micro-environmental alteration is still largely uncharacterized. In the present study, we identified elevated interleukin-17A (IL17A) in the dental pulp, which induced the osteogenesis of DPSCs after orthodontic force loading. DesignTooth movement animal models were established in Sprague-Dawley rats, and samples were harvested at 1, 4, 7, 14, and 21 days after orthodontic treatment loading. DPSC self-renewal and differentiation at different time points were examined, as well as the alteration of the microenvironment of dental pulp tissue by histological analysis and the systemic serum IL17A expression level by an ELISA assay. In vitro recombinant IL17A treatment was used to confirm the effect of IL17A on the enhancement of DPSC self-renewal and differentiation. ResultsOrthodontic treatment altered the dental pulp microenvironment by activation of the pro-inflammatory cytokine IL17A in vivo. Orthodontic loading significantly promoted the self-renewal and differentiation of DPSCs. Inflammation and elevated IL17A secretion occurred in the dental pulp during orthodontic tooth movement. Moreover, in vitro recombinant IL17A treatment mimicked the enhancement of the self-renewal and differentiation of DPSCs. ConclusionsOrthodontic treatment enhanced the differentiation and self-renewal of DPSCs, mediated by orthodontic-induced inflammation and subsequent elevation of IL17A level in the dental pulp microenvironment.

Abstract 101: Interleukin 17A Upregulates Both Renal Proximal and Distal Tubule Sodium Transporters in Angiotensin II-dependent Hypertension

We have previously shown that angiotensin II (Ang II)-induced hypertension is associated with an increase in T cell production of interleukin 17A (IL17A), and that IL17A promotes hypertension and end-organ damage. However, the precise mechanism is unknown. Recently, we reported that Ang II infusion into C56Bl/6J wild type (WT) mice blunted the rate of natriuresis following an acute saline challenge, while the rate of salt and water excretion in IL17A-/- mice was unaffected by Ang II. Following 2 weeks of Ang II infusion (490 ng/kg/min), proximal tubule sodium hydrogen exchanger 3 (NHE3) abundance was depressed in IL17A-/- but not WT mice, suggesting enhanced pressure natriuresis in IL17A-/- mice. We then performed renal transporter profiling on mice deficient in IL17A, or the related isoform IL17F, after prolonged (4 weeks) of Ang II infusion (490 ng/kg/min), a time when the blood pressure reduction in IL17A-/- mice is most prominent. Interestingly, at this time, deficiency of IL17A, but not IL17F, blunted the activation of distal tubule transporters, specifically sodium-chloride cotransporter (NCC) and the epithelial sodium channel (ENaC). We hypothesized that IL17A directly modulates renal sodium transporters as a mechanism to regulate salt and water excretion and hypertension. To test this hypothesis, we treated cultured human renal proximal tubule cells and mouse distal convoluted tubule (mDCT15) cells with recombinant IL17A or IL17F. We found that IL17A, but not IL17F, increased NHE3 protein levels (1.4-fold, p=0.003) and SGK1 mRNA expression (3.9-fold, p=0.01). In mDCT15 cells, IL17A but not IL17F, increased NCC activity as measured by thiazide-inhibited sodium uptake (1.78 vs 1.62 μmol/mg/20min, p&lt;0.001), and this increase was significantly blunted with an SGK1 inhibitor (GSK 650394) and in cells lacking Nedd4-2 (an E3 ubiquitin ligase downstream of SGK1). Moreover, in mDCT15 cells, acute IL17A treatment caused phosphorylation of SGK1 on Ser78. These studies are the first to describe a mechanistic link by which IL17A modulates renal sodium transporters and suggests that targeting IL17A may improve renal function and slow the progression to renal failure in hypertension and other autoimmune disorders.

IL-17 protects T cells from apoptosis and contributes to development of ALPS-like phenotypes

AbstractIn autoimmune/lymphoproliferative syndrome (ALPS), defective Fas death receptor function causes lymphadenomegaly/splenomegaly, the expansion of T-cell receptor αβ+ CD4/CD8 double-negative T cells, and frequent development of hematologic autoimmunity. Dianzani autoimmune lymphoproliferative disease (DALD) has a similar phenotype but lacks the expansion of double-negative T cells. This work shows that patients with ALPS and DALD have high serum levels of interleukin 17A (IL-17A), IL-17F, and IL-17AF, which are involved in several autoimmune diseases, and that their T cells show increased secretion of these cytokines upon activation in vitro. The following data indicate that these cytokines may contribute to ALPS and DALD: (1) recombinant IL-17A and IL-17F significantly inhibit Fas-induced cell death in Fas-sensitive T cells from healthy donors; (2) this inhibitory effect is also induced by the patients' serum and is reversed by anti–IL-17A antibodies; (3) IL-17A neutralization substantially increases Fas-induced cell death in T cells from ALPS and DALD patients in vitro; and (4) treatment with anti–IL-17A antibodies ameliorates the autoimmune manifestations and, at a lesser extent, the lymphoproliferative phenotype and prolongs survival in MRLlpr/lpr mice, which are an animal model of ALPS. These data suggest that IL-17A and IL-17F could be targeted therapeutically to improve Fas function in ALPS and DALD.

The role of interchain disulfide bond in a recombinant human interleukin-17A variant

Interleukin-17A (IL-17A) is the prototype of IL-17 family and has been implicated in the pathogenesis of a variety of autoimmune diseases. Therefore its structural and functional properties are of great medical interest. During our research on a recombinant human IL-17A (rhIL-17A) variant, four isoforms were obtained when it was refolded. While isoforms 1 and 2 represented non-covalent dimers, isoforms 3 and 4 were determined to be covalent dimers. All four isoforms were structurally similar by Circular Dichroism and fluorescence spectroscopy studies, but differential scanning calorimetry demonstrated thermal stability in the order of isoform 1=isoform 2<isoform 4<isoform 3. In addition, compared to covalent dimers (isoform 3 and 4), the non-covalent dimers (isoforms 1 and 2) are slightly less active in a receptor-binding assay but at least 5-fold less active in a cell-based assay.