Absence Of IL-17RA Research Articles

Abstract 1188: IL-17/IL-17RA signaling in the pancreatic epithelium upregulates B7-H4 to promote tumorigenesis

Abstract Pancreatic ductal adenocarcinoma (PDAC) is expected to overtake other cancers as the second leading cause of death from cancer. PDAC is distinguished by the early formation of a highly immunosuppressive fibro-cellular tumor microenvironment (TME). Our group has demonstrated that IL-17 is necessary for the development and spread of pancreatic cancer, but we have not yet identified the cellular compartment responsible for IL-17-mediated tumor promotion. We propose that early pancreatic carcinogenesis is mediated by modification of an immunosuppressive program and is dependent on pancreatic epithelial IL-17/IL-17RA signaling. We created mice with Kras activated and IL-17RA selectively deleted from the pancreatic compartment (KC; IL-17RAfl/fl). In order to specifically remove IL-17RA from hematopoietic cells, we implanted IL-17RA deficient (IL17-RA−/−) bone marrow cells into KC animals. While deletion of IL-17RA in the hematological compartment had no effect on the progression of pancreatic carcinogenesis, deletion of IL-17RA from the epithelial compartment delayed the development of premalignant lesions, indicating that the pancreatic epithelium is the compartment required for IL-17/IL-17RA signaling during tumorigenesis. Deletion of IL-17RA from the oncogenic epithelium resulted in increased cytotoxic CD8+T cells infiltration in the TME. To learn more about the transcriptional alterations brought on by the lack of IL-17RA in the pancreatic compartment we performed single cell sequencing of pancreas tissue of KC and KC; IL-17RAfl/fl. We found that the absence of IL-17RA in the pancreatic compartment had an impact on epithelial cells transcriptional profiles, with modulation of several immune pathways including regulation of B7-H4, a negative regulator of T cells through Eomes activation. We have generated pancreatic cancer transgenic animals that lack B7-H4 and found that KC; B7-H4−/− mice have delayed tumorigenesis and decreased immunosuppression. In sum, we describe a novel IL-17-mediated regulation of B7-H4 and unravel its function in pancreatic tumorigenesis. Citation Format: Susana Castro Pando, Le Li, Rian Morgan Howel, Marilina Mascaro, Olivereen Le Roux, David Romanin, Erick Riquelme, Yu Zhang, Jay Kolls, Seyed Javad Moghaddam, Florencia McAllister. IL-17/IL-17RA signaling in the pancreatic epithelium upregulates B7-H4 to promote tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1188.

The Role of Interleukin-17 in Tissue Protection during Radiation-Induced Oral Mucositis

<h3>Purpose/Objective(s)</h3> Oral mucositis (OM) is a common non-hematological side effect of radiotherapy and chemotherapy for head and neck cancers. Tissue injury associated with OM is painful, and can be difficult to treat. While the clinical progression of OM is understood, the signaling networks involved in the progression and resolution of damage have not been fully elucidated. Interleukin-17 (IL-17) is a proinflammatory cytokine produced by ‘type-17' lymphocytes, including T-helper 17 (Th17) cells. IL-17 is important in host protection against microbes, but it also can be pathogenic in autoimmune conditions. The role of IL-17 in other inflammatory disorders is not straightforward either. Due to the proliferative and inflammatory properties of IL-17 it is implicated in several malignancies, including esophageal cancer and tongue squamous cell carcinoma. Yet, in the distal gastrointestinal tract, IL-17 can be protective in tissue repair and maintenance. We set out to determine the role of IL-17 during severe ulceration of the oral mucosa associated with head and neck irradiation. We hypothesized that IL-17 is beneficial in repair of the oral mucosa after radiation exposure. <h3>Materials/Methods</h3> We approached this question by exposing wild-type (WT) mice and mice deficient in the receptor for IL-17, IL-17RA (<i>Il17ra</i>^−/−), to head and neck irradiation (HNI)-induced OM. Mice received a single dose of 22.5Gy of targeted irradiation using 6 MeV electrons from a linear accelerator. Tongue tissue was excised and processed for RNA-Seq analysis. The tissue was assessed macroscopically and histologically for damage, and the immune cells present in the oral tissue after HNI were determined by flow cytometry. <h3>Results</h3> RNA-Seq of oral tissue showed elevated expression of IL-17 and related immune pathways in response to HNI. Mice lacking IL-17RA exhibited markedly more severe OM. Restoration of the oral mucosa was compromised in the <i>Il17ra</i>^−/- mice and components associated with healing were diminished. The absence of IL-17RA also resulted in excess neutrophils and immunopathology compared to WT mice. <h3>Conclusion</h3> IL-17RA is required to prevent severe mucosal damage, and optimize healing after ionizing radiation. IL-17RA contributes to the proliferative capacity of the oral epithelia and maintains immune cell balance in the oral mucosa creating an environment conducive to restoration of the damaged tissue. This important contribution of IL-17 post-irradiation has implications for other cancer therapies related to the Th17 pathway.

IL-17RA receptor signaling contributes to lung inflammation and parasite burden during Toxocara canis infection in mice.

IL-17 is a cytokine produced by innate and acquired immunity cells that have an action against fungi and bacteria. However, its action in helminth infections is unclear, including in Toxocara canis infection. Toxocariasis is a neglected zoonosis representing a significant public health problem with an estimated seroprevalence of 19% worldwide. In the present study, we describe the immunopathological action of IL-17RA in acute T. canis infection. C57BL/6j (WT) and IL-17RA receptor knockout (IL-17RA-/-) mice were infected with 1000 T. canis eggs. Mice were evaluated 3 days post-infection for parasite load and white blood cell count. Lung tissue was harvested for histopathology and cytokine expression. In addition, we performed multiparametric flow cytometry in the BAL and peripheral blood, evaluating phenotypic and functional changes in myeloid and lymphoid populations. We showed that IL-17RA is essential to control larvae load in the lung; however, IL-17RA contributed to pulmonary inflammation, inducing inflammatory nodular aggregates formation and presented higher pulmonary IL-6 levels. The absence of IL-17RA was associated with a higher frequency of neutrophils as a source of IL-4 in BAL, while in the presence of IL-17RA, mice display a higher frequency of alveolar macrophages expressing the same cytokine. Taken together, this study indicates that neutrophils may be an important source of IL-4 in the lungs during T. canis infection. Furthermore, IL-17/IL-17RA axis is important to control parasite load, however, its presence triggers lung inflammation that can lead to tissue damage.

IL–17 receptor signaling regulates Citrobacter rodentium growth

Abstract The type 17 cytokine receptors are thought to play critical roles in mucosal immunity. We have shown that intestinal epithelial expression of IL–17 receptor control the development of microbiota in the terminal ileum and conditional deletion of these receptors results in overgrowth of segmented filamentous bacteria. To study the roles of these receptors in response to an attaching and effacing pathogen we challenged intestinal specific Il17ra mice and Il17rc mice with Citrobacter rodentium (C. rodentium). Conditional deletion of Il17ra and l17rc Iresulted in increased bacterial growth in the colon as well as enhanced dissemination to the liver suggesting that intestinal epithelial IL–17 receptors expression is required for control of this infection. This was supported by unbiased RNAseq analysis of the colon that showed diminished expression of Pigr, Tnfsf13 and Nox1 in the absence of Il17ra. IgA has crucial role in mucosal immunity to protect from pathogenic bacteria. PIGR binds dimeric IgA and translocation into lumen, while TNFSF13 activates induce differentiation to plasma cells following–crass switch. C. rodentium specific IgA in stool and C. rodentium specific IgA producing cells in lamina propria were reduced in Il17ra mice. These results suggested IL-17 receptor signaling regulates transcytosis of C. rodentium specific IgA as well as secretion of bacteria specific IgA. On the other hands Nox1 can produce apical hydrogen peroxide. Nox1 null mice were more sensitive for C. rodentium infection. Furthermore Nox1 was expressed by IL–17A stimulation in colonic organoid. Taken together, IL–17 receptor signaling control to produce C. rodentium specific IgA through PIGR and TNFSF13 as well as hydrogen peroxide through NOX1.

IL-17RA-Signaling Modulates CD8+ T Cell Survival and Exhaustion During Trypanosoma cruzi Infection.

The IL-17 family contributes to host defense against many intracellular pathogens by mechanisms that are not fully understood. CD8+ T lymphocytes are key elements against intracellular microbes, and their survival and ability to mount cytotoxic responses are orchestrated by several cytokines. Here, we demonstrated that IL-17RA-signaling cytokines sustain pathogen-specific CD8+ T cell immunity. The absence of IL-17RA and IL-17A/F during Trypanosoma cruzi infection resulted in increased tissue parasitism and reduced frequency of parasite-specific CD8+ T cells. Impaired IL-17RA-signaling in vivo increased apoptosis of parasite-specific CD8+ T cells, while in vitro recombinant IL-17 down-regulated the pro-apoptotic protein BAD and promoted the survival of activated CD8+ T cells. Phenotypic, functional, and transcriptomic profiling showed that T. cruzi-specific CD8+ T cells derived from IL-17RA-deficient mice presented features of cell dysfunction. PD-L1 blockade partially restored the magnitude of CD8+ T cell responses and parasite control in these mice. Adoptive transfer experiments established that IL-17RA-signaling is intrinsically required for the proper maintenance of functional effector CD8+ T cells. Altogether, our results identify IL-17RA and IL-17A as critical factors for sustaining CD8+ T cell immunity to T. cruzi.

House dust mite-driven neutrophilic airway inflammation in mice with TNFAIP3-deficient myeloid cells is IL-17-independent.

Asthma is a heterogeneous disease of the airways that involves several types of granulocytic inflammation. Recently, we have shown that the activation status of myeloid cells regulated by TNFAIP3/A20 is a crucial determinant of eosinophilic or neutrophilic airway inflammation. However, whether neutrophilic inflammation observed in this model is dependent on IL-17 remains unknown. In this study, we investigated whether IL-17RA-signalling is essential for eosinophilic or neutrophilic inflammation in house dust mite (HDM)-driven airway inflammation. Tnfaip3fl/fl xLyz2+/cre (Tnfaip3LysM-KO ) mice were crossed to Il17raKO mice, generating Tnfaip3LysM Il17raKO mice and subjected to an HDM-driven airway inflammation model. Both eosinophilic and neutrophilic inflammation observed in HDM-exposed WT and Tnfaip3LysM-KO mice respectively were unaltered in the absence of IL-17RA. Production of IL-5, IL-13 and IFN-γ by CD4+ T cells was similar between WT, Tnfaip3LysM-KO and Il17raKO mice, whereas mucus-producing cells in Tnfaip3LysM-KO Il17raKO mice were reduced compared to controls. Strikingly, spontaneous accumulation of pulmonary Th1, Th17 and γδ-17 T cells was observed in Tnfaip3LysM-KO Il17raKO mice, but not in the other genotypes. Th17 cell-associated cytokines such as GM-CSF and IL-22 were increased in the lungs of HDM-exposed Tnfaip3LysM-KO Il17raKO mice, compared to IL-17RA-sufficient controls. Moreover, neutrophilic chemo-attractants CXCL1, CXCL2, CXCL12 and Th17-promoting cytokines IL-1β and IL-6 were unaltered between Tnfaip3LysM-KO and Tnfaip3LysM-KO Il17raKO mice. These findings show that neutrophilic airway inflammation induced by activated TNFAIP3/A20-deficient myeloid cells can develop in the absence of IL-17RA-signalling. Neutrophilic inflammation is likely maintained by similar quantities of pro-inflammatory cytokines IL-1β and IL-6 that can, independently of IL-17-signalling, induce the expression of neutrophil chemo-attractants.

Neutralization of either IL-17A or IL-17F is sufficient to inhibit house dust mite induced allergic asthma in mice.

T helper (Th)17 immune response participates in allergic lung inflammation and asthma is reduced in the absence of interleukin (IL)-17 in mice. Since IL-17A and IL-17F are induced and bind the shared receptor IL-17RA, we asked whether both IL-17A and IL-17F contribute to house dust mite (HDM) induced asthma. We report that allergic lung inflammation is attenuated in absence of either IL-17A or IL-17F with reduced airway hyperreactivity, eosinophilic inflammation, goblet cell hyperplasia, cytokine and chemokine production as found in absence of IL-17RA. Furthermore, specific antibody neutralization of either IL-17A or IL-17F given during the sensitization phase attenuated allergic lung inflammation and airway hyperreactivity. In vitro activation by HDM of primary dendritic cells revealed a comparable induction of CXCL1 and IL-6 expression and the response to IL-17A and IL-17F relied on IL-17RA signaling via the adaptor protein act1 in fibroblasts. Therefore, HDM-induced allergic respiratory response depends on IL-17RA via act1 signaling and inactivation of either IL-17A or IL-17F is sufficient to attenuate allergic asthma in mice.

The IL-17F/IL-17RC Axis Promotes Respiratory Allergy in the Proximal Airways

The interleukin 17 (IL-17) cytokine and receptor family is central to antimicrobial resistance and inflammation in the lung. Mice lacking IL-17A, IL-17F, or the IL-17RA subunit were compared with wild-type mice for susceptibility to airway inflammation in models of infection and allergy. Signaling through IL-17RA was required for efficient microbial clearance and prevention of allergy; in the absence of IL-17RA, signaling through IL-17RC on epithelial cells, predominantly by IL-17F, significantly exacerbated lower airway Aspergillus or Pseudomonas infection and allergic airway inflammation. In contrast, following infection with the upper respiratory pathogen Staphylococcus aureus, the IL-17F/IL-17RC axis mediated protection. Thus, IL-17A and IL-17F exert distinct biological effects during pulmonary infection; the IL-17F/IL-17RC signaling axis has the potential to significantly worsen pathogen-associated inflammation of the lower respiratory tract in particular, and should be investigated further as a therapeutic target for treating pathological inflammation in the lung.

IL-17 Receptor A Maintains and Protects the Skin Barrier To Prevent Allergic Skin Inflammation.

Atopic dermatitis (AD) is a common inflammatory skin disease affecting up to 20% of children and 3% of adults worldwide and is associated with dysregulation of the skin barrier. Although type 2 responses are implicated in AD, emerging evidence indicates a potential role for the IL-17A signaling axis in AD pathogenesis. In this study we show that in the filaggrin mutant mouse model of spontaneous AD, IL-17RA deficiency (Il17ra-/- ) resulted in severe exacerbation of skin inflammation. Interestingly, Il17ra-/- mice without the filaggrin mutation also developed spontaneous progressive skin inflammation with eosinophilia, as well as increased levels of thymic stromal lymphopoietin (TSLP) and IL-5 in the skin. Il17ra-/- mice have a defective skin barrier with altered filaggrin expression. The barrier dysregulation and spontaneous skin inflammation in Il17ra-/- mice was dependent on TSLP, but not the other alarmins IL-25 and IL-33. The associated skin inflammation was mediated by IL-5-expressing pathogenic effector Th2 cells and was independent of TCRγδ T cells and IL-22. An absence of IL-17RA in nonhematopoietic cells, but not in the hematopoietic cells, was required for the development of spontaneous skin inflammation. Skin microbiome dysbiosis developed in the absence of IL-17RA, with antibiotic intervention resulting in significant amelioration of skin inflammation and reductions in skin-infiltrating pathogenic effector Th2 cells and TSLP. This study describes a previously unappreciated protective role for IL-17RA signaling in regulation of the skin barrier and maintenance of skin immune homeostasis.

Interleukin-17RA Promotes Humoral Responses and Glomerular Injury in Experimental Rapidly Progressive Glomerulonephritis

Background/Aims: Interleukin (IL)-17A and IL-17F are proinflammatory cytokines, which signal through a receptor complex consisting of IL-17RA and IL-17RC subunits. We sought to define the role of IL-17RA expression by leukocytes and stromal cells in nephritogenic immunity and injury in experimental glomerulonephritis. Methods: Glomerulonephritis was induced in wild-type and IL-17RA-deficient (IL-17RA^-/-) mice by sheep anti-mouse glomerular basement membrane globulin. Renal injury and immune responses were assessed at day 21. Glomerulonephritis was induced in bone marrow (BM) chimeric mice, with either BM or tissue cell (TC) deficiency of IL-17RA. To assess humoral responses, WT and IL-17RA^-/- mice were sensitized to sheep globulin and euthanized 10 days later. Results: IL-17RA^-/- mice had reduced glomerular crescent formation, neutrophils and macrophages compared to wild-type mice, while nephritic BM-TC+ mice developed less glomerular segmental necrosis. IL-17RA expression was required in both BM and TC for maximal systemic interferon-γ expression. Antigen-specific humoral immune responses were impaired in the absence of IL-17RA. Compared to BM+TC+ mice, glomerular IgG and C3 deposition was reduced in BM+TC- and BM-TC+ mice, respectively. Humoral immunity was also impaired in BM- and TC-deficient chimeras. BM+TC- mice had fewer B cells expressing CXCR5, while IL-17RA^-/- mice had abnormal germinal centre development after immunization, with reduced follicular B cell and follicular helper T-cell CXCR5 expression, explaining the impaired humoral immunity. Conclusion: IL-17RA contributes to experimental glomerulonephritis, with IL-17RA expression on both leukocytes and stromal cells being required for the full expression of nephritogenic humoral immunity.

Interleukin 17 Receptor A Modulates Monocyte Subsets and Macrophage Generation In Vivo

Interleukin (IL)-17A signaling via Interleukin 17 receptor A (Il17ra) contributes to the inflammatory host response by inducing recruitment of innate immune cells, but also plays a role in homeostatic neutrophilic granulocyte regulation. Monocytes, the other main innate immune cell, have a longer life span and can pursue multiple differentiation pathways towards tissue macrophages. Monocytes are divided into two subpopulations by expression of the Ly6C/Gr1 surface marker in mice. We here investigated the role of Il17ra in monocyte homeostasis and macrophage generation. In Il17ra-/- and in mixed bone marrow chimeric wt/Il17ra-/- mice, the concentrations of circulating Il17ra-/-Gr1low monocytes were significantly decreased compared to wt cells. Pulmonary, splenic and resident peritoneal Il17ra-/- macrophages were significantly fewer than of wt origin. Bone marrow progenitor and monocyte numbers were equal, but the proportion of Il17ra-/-Gr1low monocytes was already decreased at bone marrow level. After monocyte depletion, initial Gr1high and Gr1low monocyte regeneration of Il17ra-/- and wt cells was very similar. However, Il17ra-/-Gr1low counts were not sustained. After labeling with either fluorescent beads or BrdU, Il17ra-/-Gr1high monocyte transition to Gr1low cells was not detectable unlike wt cells. Monocyte recruitment in acute peritonitis, which is known to be largely due to Gr1high cell migration, was unaffected in an identical environment. Unilateral ureteral obstruction induces a less acute inflammatory and fibrotic kidney injury. Compared to wt cells in the same environment, Il17ra-/- macrophage accumulation in the kidney was decreased. In the absence of Il17ra on all myeloid cells, renal fibrosis was significantly attenuated. Our data show that Il17ra modulates Gr1low monocyte counts and suggest defective Gr1high to Gr1low monocyte transition as an underlying mechanism. Lack of Il17ra altered homeostatic tissue macrophage formation and diminished renal inflammation and fibrosis. Il17ra appears to be a novel modulator of monocyte phenotype and possible therapeutic target in renal fibrosis.

IL-17RA Signaling Reduces Inflammation and Mortality during Trypanosoma cruzi Infection by Recruiting Suppressive IL-10-Producing Neutrophils

Members of the IL-17 cytokine family play an important role in protection against pathogens through the induction of different effector mechanisms. We determined that IL-17A, IL-17E and IL-17F are produced during the acute phase of T. cruzi infection. Using IL-17RA knockout (KO) mice, we demonstrate that IL-17RA, the common receptor subunit for many IL-17 family members, is required for host resistance during T. cruzi infection. Furthermore, infected IL-17RA KO mice that lack of response to several IL-17 cytokines showed amplified inflammatory responses with exuberant IFN-γ and TNF production that promoted hepatic damage and mortality. Absence of IL-17RA during T. cruzi infection resulted in reduced CXCL1 and CXCL2 expression in spleen and liver and limited neutrophil recruitment. T. cruzi-stimulated neutrophils secreted IL-10 and showed an IL-10-dependent suppressive phenotype in vitro inhibiting T-cell proliferation and IFN-γ production. Specific depletion of Ly-6G+ neutrophils in vivo during T. cruzi infection raised parasitemia and serum IFN-γ concentration and resulted in increased liver pathology in WT mice and overwhelming wasting disease in IL-17RA KO mice. Adoptively transferred neutrophils were unable to migrate to tissues and to restore resistant phenotype in infected IL-17RA KO mice but migrated to spleen and liver of infected WT mice and downregulated IFN-γ production and increased survival in an IL-10 dependent manner. Our results underscore the role of IL-17RA in the modulation of IFN-γ-mediated inflammatory responses during infections and uncover a previously unrecognized regulatory mechanism that involves the IL-17RA-mediated recruitment of suppressive IL-10-producing neutrophils.