IL-17A Responses Research Articles

Abstract PR10: Candida albicans infection mediates gastrointestinal track malignancy independently of Il17a in an APECED mouse model

Abstract The cytokine Il17a plays an important role in protection against fungal infection, yet it also serves as a pathogenic factor in several inflammation-related cancers. Previously we reported that fungal infection promotes the development of esophageal squamous cell carcinoma (ESCC) in the IKKalpha kinase-dead KA knock-in (KA) mice that mimic a human autoimmune disorder, autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). Our data showed that KA T cells failed to induce Il17a in response to fungal infection. However, the role of Il17a in fungal infection-mediated esophageal carcinogenesis remains to be further determined. In this study, we crossed KA mice with Il17a-/- mice to generate KA;Il17a-/- double mutant mice. We orally inoculated WT, Il17a-/-, KA, and KA;Il17a-/- mice with Candida albicans weekly for 3 months to investigate gastrointestinal (GI) track tumorigenesis, including the SCC development in the oral cavity, esophagus, and forestomach. We found that loss of Il17a leads to much earlier onset of GI track tumors in KA;Il17a-/- mice than that in KA mice. KA;Il17a-/- mice also died much earlier compared to KA mice, which is likely due to increased C. albicans burden in the absence of Il17a. The incidence of GI track tumors is comparable between KA and KA;Il17a-/- mice, suggesting that C. albicans infection-associated GI track tumorigenesis is independent of Il17a in KA mouse model. To further understand the underlying mechanism, we performed single-cell RNA sequencing analysis for CD45+ immune cells isolated from long-term C. alibicans-infected mouse esophagi of WT, Il17a-/-, KA, and KA;Il17a-/- mouse cohorts. Interestingly, the neutrophil population was significantly increased in the esophagi of KA and KA;Il17a-/- mice compared to WT and Il17a-/- mice. However, KA neutrophils exhibited reduced capacity in killing C. albicans with reduced NETs formation compared to WT neutrophils, suggesting that the defect in NETs formation may play a pivotal role in GI track tumorigenesis in the context of fungal infection. We are currently investigating how the interplay between C. albicans infection and host neutrophils regulates Candida infection-associated GI track tumorigenesis. This abstract is also being presented as Poster B01. Citation Format: Feng Zhu, Jami Willette-Brown, Trang Phan, Yongmei Zhao, Bao Tran, Scott G. Filler, Mihalis S. Lionakis, Yinling Hu. Candida albicans infection mediates gastrointestinal track malignancy independently of Il17a in an APECED mouse model [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr PR10.

CUX1 and IκBζ (NFKBIZ) mediate the synergistic inflammatory response to TNF and IL-17A in stromal fibroblasts

The role of stromal fibroblasts in chronic inflammation is unfolding. In rheumatoid arthritis, leukocyte-derived cytokines TNF and IL-17A work together, activating fibroblasts to become a dominant source of the hallmark cytokine IL-6. However, IL-17A alone has minimal effect on fibroblasts. To identify key mediators of the synergistic response to TNF and IL-17A in human synovial fibroblasts, we performed time series, dose-response, and gene-silencing transcriptomics experiments. Here we show that in combination with TNF, IL-17A selectively induces a specific set of genes mediated by factors including cut-like homeobox 1 (CUX1) and IκBζ (NFKBIZ). In the promoters of CXCL1, CXCL2, and CXCL3, we found a putative CUX1-NF-κB binding motif not found elsewhere in the genome. CUX1 and NF-κB p65 mediate transcription of these genes independent of LIFR, STAT3, STAT4, and ELF3. Transcription of NFKBIZ, encoding the atypical IκB factor IκBζ, is IL-17A dose-dependent, and IκBζ only mediates the transcriptional response to TNF and IL-17A, but not to TNF alone. In fibroblasts, IL-17A response depends on CUX1 and IκBζ to engage the NF-κB complex to produce chemoattractants for neutrophil and monocyte recruitment.

The development of colitis in Il10-/- mice is dependent on IL-22.

Mice deficient in the IL-10 pathway are the most widely-used models of intestinal immunopathology.IL-17A is strongly implicated in gut disease in mice and humans, but conflicting evidence has drawn IL-17’s role in the gut into question.IL-22 regulates antimicrobial and repair activities of intestinal epithelial cells (IECs) and is closely associated with IL-17A responses but it’s role in chronic disease is uncertain. We report that IL-22, like IL-17A, is aberrantly expressed in colitic Il10−/− mice. While IL-22+Th17 cells were elevated in the colon, IL-22-producing ILC3s were highly enriched in the small intestines of Il10−/− mice. Remarkably, Il10−/−Il22−/− mice did not develop colitis despite retaining high levels of Th17 cells and remaining colonized with colitogenic Helicobacter spp.. Accordant with IL-22-induced IEC proliferation, the epithelia hyperplasia observed in Il10−/− animals was reversed in Il10−/−Il22−/− mice. Also, the high levels of antimicrobial IL-22-target genes, including Reg3g, were normalized in Il10−/−Il22−/− mice. Consistent with a heightened antimicrobial environment, Il10−/− mice had reduced diversity of the fecal microbiome that was reestablished in Il10−/−Il22−/− animals. These data suggest that spontaneous colitis in Il10−/− mice is driven by IL-22 and implicates an underappreciated IL-10-IL-22 axis in regulating intestinal homeostasis.

IL-13 and IL-4, but not IL-5 nor IL-17A, induce hyperresponsiveness in isolated human small airways

Specific inflammatory pathways are indicated to contribute to severe asthma, but their individual involvement in the development of airway hyperresponsiveness remains unexplored. This experimental study in human small bronchi aimed to provide insight into which of the type 2 and type 17 cytokines cause hyperresponsiveness of airway smooth muscle. Explanted small bronchi isolated from human lung tissue and human airway smooth muscle cells were treated for 2 and 1 day(s), respectively, with 100 ng/mL of IL-4, IL-5, IL-13, or IL-17A, and contractile responses, Ca2+ mobilization, and receptor expression were assessed. Treatment with IL-13 increased the potency of histamine, carbachol, and leukotriene D4 as contractile agonists. IL-4, but not IL-5 or IL-17A, also increased the potency of histamine. In human airway smooth muscle cells, IL-13 and IL-4, but not IL-5 and IL-17A, enhanced the histamine-induced Ca2+ mobilization that was accompanied with increased mRNA expression of histamine H1 and cysteinyl leukotriene CysLT1 receptors. RNA sequencing of isolated bronchi confirmed the IL-13-mediated upregulation of H1 and CysLT1 receptors, without showing an alteration of muscarinic M3 receptors. Dexamethasone had no effects on IL-13-induced hyperresponsiveness in human bronchi, the increased Ca2+ mobilization, or the enhanced receptor expression. In contrast, antagonism of the common receptor for IL-13 and IL-4 by the biologic dupilumab prevented the effects of both IL-13 and IL-4 in human bronchi and human airway smooth muscle cells. The glucocorticoid-insensitive hyperrresponsiveness in isolated human airways induced by IL-13 and IL-4 provides further evidence that the IL-4Rα pathway should be targeted as a new strategy for the treatment of airway hyperresponsiveness in asthma.

Differential IL-17A response to S. pneumoniae in adenoid tissue of children with sleep disordered breathing and otitis media with effusion

Streptococcus pneumonia, one of the major colonizers in nasopharyngeal adenoids, has been the predominant pathogen causing acute otitis media (AOM) in children. Recent evidence suggests an association between IL-17A-mediated immune response and the clearance of pneumococcal colonization in nasopharyngeal adenoids. Here, we evaluated the expressions of IL-17A and associated genes in hypertrophic adenoid tissues of children with sleep-disordered breathing (SDB) and otitis media with effusion (OME) and their association with pneumococcal carriage. Sixty-six pediatric patients with adenoid hypertrophy were enrolled. During adenoidectomy, nasopharyngeal swab and adenoid tissues were used to determine pneumococcal carriage and IL-17A expression. Our results revealed significantly higher levels of IL-17A and IL-17A:IL-10 mRNA in the SDB patients positive for nasopharyngeal pneumococcal carriage than those negative. However, these differences were not significant in the OME group. These results suggested, in OME patients, prolonged or chronic pneumococcal carriage may occur because of insufficient IL-17A-mediated mucosal clearance, and could further lead to AOM and OME development.

Extracellular Membrane Vesicles from Lactobacilli Dampen IFN-\u03b3 Responses in a Monocyte-Dependent Manner

Secreted factors derived from Lactobacillus are able to dampen pro-inflammatory cytokine responses. Still, the nature of these components and the underlying mechanisms remain elusive. Here, we aimed to identify the components and the mechanism involved in the Lactobacillus-mediated modulation of immune cell activation. PBMC were stimulated in the presence of the cell free supernatants (CFS) of cultured Lactobacillus rhamnosus GG and Lactobacillus reuteri DSM 17938, followed by evaluation of cytokine responses. We show that lactobacilli-CFS effectively dampen induced IFN-γ and IL-17A responses from T- and NK cells in a monocyte dependent manner by a soluble factor. A proteomic array analysis highlighted Lactobacillus-induced IL-1 receptor antagonist (ra) as a potential candidate responsible for the IFN-γ dampening activity. Indeed, addition of recombinant IL-1ra to stimulated PBMC resulted in reduced IFN-γ production. Further characterization of the lactobacilli-CFS revealed the presence of extracellular membrane vesicles with a similar immune regulatory activity to that observed with the lactobacilli-CFS. In conclusion, we have shown that lactobacilli produce extracellular MVs, which are able to dampen pro-inflammatory cytokine responses in a monocyte-dependent manner.

Cutaneous Immune Cell-Microbiota Interactions Are Controlled by Epidermal JunB/AP-1

SummaryAtopic dermatitis (AD) is a multi-factorial skin disease with a complex inflammatory signature including type 2 and type 17 activation. Although colonization by S. aureus is common in AD, the mechanisms rendering an organism prone to dysbiosis, and the role of IL-17A in the control of S. aureus-induced skin inflammation, are not well understood. Here, we show several pathological aspects of AD, including type 2/type 17 immune responses, elevated IgE, barrier dysfunction, pruritus, and importantly, spontaneous S. aureus colonization in JunBΔep mice, with a large transcriptomic overlap with AD. Additionally, using Rag1−/− mice, we demonstrate that adaptive immune cells are necessary for protection against S. aureus colonization. Prophylactic antibiotics, but not antibiotics after established dysbiosis, reduce IL-17A expression and skin inflammation, examined using Il17a-eGFP reporter mice. Mechanistically, keratinocytes lacking JunB exhibit higher MyD88 levels in vitro and in vivo, previously shown to regulate S. aureus colonization. In conclusion, our data identify JunB as an upstream regulator of microbiota-immune cell interactions and characterize the IL-17A response upon spontaneous dysbiosis.

Riemerella anatipestifer infection in ducks induces IL-17A production, but not IL-23p19

R. anatipestifer (RA) is one of the most harmful bacterial pathogens affecting the duck industry, and infection is associated with the production of proinflammatory cytokines, including IL-17A. Another proinflammatory cytokine, IL-23, is critical for the development of Th17 cells, which produce IL-17. However, IL-23 roles have not been studied in this infection. Here, we describe the identification and mRNA expression analysis of duck IL-23p19 (duIL-23p19) in splenic lymphocytes and macrophages stimulated with killed RA and in spleens of RA-infected ducks. Expression of duIL-23p19 transcript identified in this study was relatively high in livers of healthy ducks and was upregulated in mitogen-activated splenic lymphocytes as well as in splenic lymphocytes and macrophages stimulated with killed RA. In spleens of RA-infected ducks, expression levels of duIL-23p19 transcript were unchanged at all time points except on days 4 and 7 post-infection; however, duIL-17A and IL-17F expression levels were upregulated in both spleens of RA-infected ducks and splenic lymphocytes and macrophages stimulated with killed RA. In sera collected at 24 h after this infection, duIL-23p19 expression levels were unchanged, whereas IL-17A significantly upregulated. These results suggest that IL-23p19 does not play a critical role in the IL-17A response in early stages of RA-infected ducks.

A T cell–myeloid IL-10 axis regulates pathogenic IFN-γ–dependent immunity in a mouse model of type 2–low asthma

BackgroundAlthough originally defined as a type 2 (T2) immune-mediated condition, non-T2 cytokines, such as IFN-γ and IL-17A, have been implicated in asthma pathogenesis, particularly in patients with severe disease. IL-10 regulates TH cell phenotypes and can dampen T2 immunity to allergens, but its functions in controlling non-T2 cytokine responses in asthmatic patients are unclear.ObjectiveWe sought to determine how IL-10 regulates the balance of TH cell responses to inhaled allergen.MethodsAllergic airway disease was induced in wild-type, IL-10 reporter, and conditional IL-10 or IL-10 receptor α (IL-10Rα) knockout mice by means of repeated intranasal administration of house dust mite (HDM). IL-10 and IFN-γ signaling were disrupted by using blocking antibodies.ResultsRepeated HDM inhalation induced a mixed IL-13/IL-17A response and accumulation of IL-10–producing forkhead box P3–negative effector CD4+ T cells in the lungs. Ablation of T cell–derived IL-10 increased the IFN-γ and IL-17A response to HDM, reducing IL-13 levels and airway eosinophilia without affecting IgE levels or airway hyperresponsiveness. The increased IFN-γ response could be recapitulated by IL-10Rα deletion in CD11c+ myeloid cells or local IL-10Rα blockade. Disruption of the T cell–myeloid IL-10 axis resulted in increased pulmonary monocyte–derived dendritic cell numbers and increased IFN-γ–dependent expression of CXCR3 ligands by airway macrophages, which is suggestive of a feedforward loop of TH1 cell recruitment. Augmented IFN-γ responses in the HDM allergic airway disease model were accompanied by increased disruption of airway epithelium, which was reversed by therapeutic blockade of IFN-γ.ConclusionsIL-10 from effector T cells signals to CD11c+ myeloid cells to suppress an atypical and pathogenic IFN-γ response to inhaled HDM.

Delayed development of the protective IL-17A response following a Giardia muris infection in neonatal mice

Giardia is an intestinal protozoan parasite that has the ability to infect a wide range of hosts, which can result in the clinical condition ‘giardiasis’. Over the years, experimental research has shown the crucial involvement of IL-17A to steer the protective immune response against Giardia. The development of the protective response, as reflected by a significant drop in cyst secretion, typically takes around 3 to 4 weeks. However, early-life infections often have a more chronic character lasting for several weeks or months. Therefore, the aim of the current study was to investigate the dynamics of a Giardia muris infection and the subsequent host immune response in neonatal mice infected 4 days after birth. The outcome of the study showed that a G. muris infection in pre-weaned mice failed to trigger a protective IL-17A response, which could explain the prolonged course of infection in comparison to older mice. Only after weaning, a protective intestinal immune response started to develop, characterized by an upregulation of IL-17A and Mbl2 and the secretion of parasite-specific IgA.

CD74 is a T cell antigen in spondyloarthritis

Spondyloarthritis (SpA) is a chronic inflammatory disease of unknown aetiology. Previously, we identified autoantibodies against CD74 in sera of SpA patients. The aim of this study was to evaluate CD74 as a T cell antigen in SpA. Recombinant CD74 protein and a panel of selected peptides representing its amino acid residues were examined for their capability to stimulate peripheral blood mononuclear cells from patients with SpA. In particular, cytokine production by CD4+ T cells was evaluated with flow cytometric detection of intracellular TNF-α, IFNγ, TGFβ and IL-17A. Patients' sera were tested for antibodies against CD74 using ELISA. Samples from patients with rheumatoid arthritis and healthy blood donors were similarly tested as controls. Significantly more CD4+ T cells from SpA patients produced TNF-α, IFNγ and IL-17A in response to recombinant CD74 than patients with rheumatoid arthritis or healthy blood donors. Among evaluated epitopes, the most promiscuous one lies within the peptide of the amino acid residues 142-185, which appeared more immunogenic. Further, the proportion of cytokine producing CD4+ T cells was significantly higher among SpA patients with autoantibodies against CD74. CD74 is a T cell antigen in SpA, eliciting Th1 and Th17 responses, which may be relevant in disease pathogenesis. Recognition of the highly immunogenic amino acid residues of CD74 may contribute to our understanding of autoimmune responses of T helper cells in SpA.

Prediction and Validation of Immunogenic Domains of Pneumococcal Proteins Recognized by Human CD4+ T Cells.

CD4+ T-cell mechanisms are implied in protection against pneumococcal colonization; however, their target antigens and function are not well defined. In contrast to high-throughput protein arrays for serology, basic antigen tools for CD4+ T-cell studies are lacking. Here, we evaluate the potential of a bioinformatics tool for in silico prediction of immunogenicity as a method to reveal domains of pneumococcal proteins targeted by human CD4+ T cells. For 100 pneumococcal proteins, CD4+ T-cell immunogenicity was predicted based on HLA-DRB1 binding motifs. For 20 potentially CD4+ T-cell immunogenic proteins, epitope regions were verified by testing synthetic peptides in T-cell assays using peripheral blood mononuclear cells from healthy adults. Peptide pools of 19 out of 20 proteins evoked T-cell responses. The most frequent responses (detectable in ≥20% of donors tested) were found to SP_0117 (PspA), SP_0468 (putative sortase), SP_0546 (BlpZ), SP_1650 (PsaA), SP_1923 (Ply), SP_2048 (conserved hypothetical protein), SP_2216 (PscB), and SPR_0907 (PhtD). Responding donors had diverging recognition patterns and profiles of signature cytokines (gamma interferon [IFN-γ], tumor necrosis factor alpha [TNF-α], interleukin-13 [IL-13], and/or IL-17A) against single-epitope regions. Natural HLA-DR-restricted presentation and recognition of a predicted SP_1923-derived epitope were validated through the isolation of a CD4+ T-cell clone producing IFN-γ, TNF-α, and IL-17A in response to the synthetic peptide, whole protein, and heat-inactivated pneumococcus. This proof of principle for a bioinformatics tool to identify pneumococcal protein epitopes targeted by human CD4+ T cells provides a peptide-based strategy to study cell-mediated immune mechanisms for the pneumococcal proteome, advancing the development of immunomonitoring assays and targeted vaccine approaches.

Nrf2 selectively regulates IL-22 and IL-17A production in Th17 cells

Abstract Th17 cell-derived IL-17A and IL-22 are critical for mounting both inflammatory and tissue protective responses. It remains unclear whether cytokine responses can be modified differently to achieve targeted functional outcome. A therapeutic strategy which inhibits CD4+ T cell-derived inflammatory IL-17A responses but concomitantly promotes IL-22-dependent tissue protective or regenerative response is of great clinical significance. Here, we showed that nuclear factor (erythroid-derived 2)-like 2 (Nrf2) selectively regulated IL-17A and IL-22 responses in CD4+ T cells. We found that Nrf2−/− mice had reduced IL-22 responses in Ovaalbumin (Ova) + LPS and separately concanavalin A (Con A) administered mice. Furthermore, CDDO-Im, a selective Nrf2 activator, induced IL-22 but suppressed IL-17A response in CD4+ T cells polarized under Th17 cell condition. Our qPCR data revealed that CDDO-Im-activated CD4+ T cells had lower Rorc, but increased Cybb, Sod1 and Sod3 transcript. The expression pattern of Il23r and Sod2 was unaltered. CDDO-Im-dependent IL-17A but not IL-22 response was regulated by Sod3. Interestingly, we found that CDDO-Im induced aryl hydrocarbon receptor (Ahr) and its downstream Cyp1a1 and Cyp1b1 gene expression. The luciferase reporter assay data showed that CDDO-Im regulated Ahr promoter activity in a dose-dependent manner. Additionally, CDDO-Im induced Nqo1 expression, a Nrf2-activated gene, in WT mice but not in Ahr−/− mice. Finally, we confirmed that the CDDO-Immediated induction of IL-22 production in CD4+ T cells was abrogated in Ahr−/− mice. Collectively, our data show that Nrf2 promotes IL-22 production while it inhibits IL-17A expression in Th17 cells.

Immunity of a Klebsiella Pneumoniae Vaccine Independent of Antigen Specific Antibody

Abstract Objective We demonstrated the serotype independent immunity of Klebsiella pneumoniae (K. pneumoniae) vaccine. We would like to declare next if the noble effect is dependent on the antibody specific manner. Methods Mice were vaccinated via intranasal with Kp serotype 2 OMPx adjuvanted with heat-labile enterotoxin A1 domain (LTA1) and boosted at 3 weeks after the initial immunization. Protective immunity was compared among the C57Bl/6 mice, STAT3 fl/fl×CD4 Cre mice, and Il21r −/− mice by infecting with K1 strain of K. pneumoniae. Lung T-cell responses were evaluated by FACS and ELISPOT as well as K1 strain specific antibodies were assessed by ELISA. Results CD4+ T-cells of the vaccinated lungs in the CD4+ STAT3 deficient mice were significantly decreased compared to the WT mice and the Il21r −/− mice, and IL17A response by ELISPOT were significantly reduced as well. Meanwhile, K1 strain specific IgG in the serum and IgA in the lung homogenates of vaccinated WT mice were significantly increased in vaccinated mice and these responses were reduced in vaccinated CD4+ STAT3 deficient mice and Il21r −/− mice. Furthermore, vaccine induced protection was compromised in vaccinated CD4+ STAT3 deficient mice whereas the protection as well as antigen elicited lung IL-17 responses were maintained in Il21r −/− mice. Conclusions STAT3 activation in CD4+ T-cells regulated by IL-21R signaling are required for the K. pneumoniae specific antibodies, but these antibody responses were dispensable for the serotype independent immunity LTA1 adjuvanted K. pneumoniae vaccine. However, CD4 STAT3 was essential for Th17 immunity and therapeutic efficacy of the vaccine.

The role of tyrosine kinase Itk in T helper 17 and T regulatory cells in IL17 mediated hypersensitivity pneumonitis

Abstract The balance of inflammatory and suppressive cytokines is critical in controlling inflammatory responses, and the pro- and anti-inflammatory cytokines IL17A and IL10 has been implicated in numerous pulmonary inflammatory diseases. The tyrosine kinase, Itk, plays a critical role in T cell activation. We have previously shown that Itk−/− mice do not develop allergic airway disease coupled with reduced production of IL17A in the lungs. In vitro, Itk is required for the development of Th17 cells and their production of the pro-inflammatory cytokine IL17A. Furthermore, Type I regulatory and Foxp3+ T regulatory (Tregs) cells, suppressive producers of IL10, are positively and negatively regulated by Itk respectively. Farmer’s lung is a subset of hypersensitivity pneumonitis caused by repeated exposure to the bacteria Saccharopolyspora rectivirgula (SR), and is dependent on IL17A and regulated by IL10. We find that surprisingly, exposure to SR drives robust IL17A response produced by CD4+ T cells even in the absence of Itk, accompanied by the development of pulmonary inflammation. SR also induced Itk independent development of a population of population of Foxp3+ Tregs cells that produce IL17A, accompanied by a significant decrease in Tr1 cells compared to WT mice. These studies suggest that TCR signaling through Itk differentially regulates the development of inflammatory Th17 cells and suppressive Tregs and Tr1 cells. Understanding how Itk modulates the development of Th17/Treg cytokine responses will allow us to better understand the precise role of Itk in the production of IL17A and IL10 in airway inflammation.

Expression of c-Kit discriminates between two functionally distinct subsets of human type 2 innate lymphoid cells.

Human type 2 innate lymphoid cells (ILC2) are the only ILC subset that shows heterogeneous expression of the SCF receptor c-Kit (CD117). Despite its use as surface marker to distinguish ILC populations, its influence on ILC2 biology has not been investigated. Here, we show that c-Kit expression of peripheral blood ILC distinguishes two functionally distinct ILC2 subsets (c-Kithi and c-Kitlo ). When examined for their potential for functional plasticity we found that c-Kitlo ILC2 displayed greater potential to produce type 2 cytokines, possibly representing fully mature and lineage committed ILC2. On the other hand, c-Kithi ILC2 coexpressed the ILC3-marker and chemokine receptor CCR6 and were able to mount a significant IL-17A response under ILC3-promoting conditions. In addition, c-Kithi ILC2 produced higher levels of IFN-γ than c-Kitlo ILC2 under ILC1-conditions. Although costimulation with SCF did not further influence ILC2 plasticity, it augmented type 2 cytokine production. We conclude that c-Kit marks distinct subpopulations of ILC2, which has therapeutic implications for conditions in which ILC2 are involved, such as allergy and asthma.

Segmented Filamentous Bacteria Induce Divergent Populations of Antigen-Specific CD4 T Cells in the Small Intestine.

CD4 T cells differentiate into RORγt/IL-17A-expressing cells in the small intestine following colonization by segmented filamentous bacteria (SFB). However, it remains unclear whether SFB-specific CD4 T cells can differentiate directly from naïve precursors, and whether their effector differentiation is solely directed towards the Th17 lineage. In this study, we used adoptive T cell transfer experiments and showed that naïve CD4 T cells can migrate to the small intestinal lamina propria (sLP) and differentiate into effector T cells that synthesize IL-17A in response to SFB colonization. Using single cell RT-PCR analysis, we showed that the progenies of SFB responding T cells are not uniform but composed of transcriptionally divergent populations including Th1, Th17 and follicular helper T cells. We further confirmed this finding using in vitro culture of SFB specific intestinal CD4 T cells in the presence of cognate antigens, which also generated heterogeneous population with similar features. Collectively, these findings indicate that a single species of intestinal bacteria can generate a divergent population of antigen-specific effector CD4 T cells, rather than it provides a cytokine milieu for the development of a particular effector T cell subset.

Immunization of young heifers with staphylococcal immune evasion proteins before natural exposure to Staphylococcus aureus induces a humoral immune response in serum and milk

BackgroundStaphylococcus aureus, a leading cause of mastitis in dairy cattle, causes severe mastitis and/or chronic persistent infections with detrimental effects on the cows’ wellbeing, lifespan and milk production. Despite years of research there is no effective vaccine against S. aureus mastitis. Boosting of non-protective pre-existing immunity to S. aureus, induced by natural exposure to S. aureus, by vaccination may interfere with vaccine efficacy. The aim was to assess whether experimental immunization of S. aureus naïve animals results in an immune response that differs from immunity following natural exposure to S. aureus.ResultsFirst, to define the period during which calves are immunologically naïve for S. aureus, Efb, LukM, and whole-cell S. aureus specific serum antibodies were measured in a cohort of newborn calves by ELISA. Rising S. aureus specific antibodies indicated that from week 12 onward calves mounted an immune response to S. aureus due to natural exposure. Next, an experimental immunization trial was set up using 8-week-old heifer calves (n = 16), half of which were immunized with the immune evasion molecules Efb and LukM. Immunization was repeated after one year and before parturition and humoral and cellular immunity specific for Efb and LukM was determined throughout the study. Post-partum, antibody levels against LukM and EfB were significantly higher in serum, colostrum and milk in the experimentally immunized animals compared to animals naturally exposed to S. aureus. LukM specific IL17a responses were also significantly higher in the immunized cows post-partum.ConclusionsExperimental immunization with staphylococcal immune evasion molecules starting before natural exposure resulted in significantly higher antibody levels against Efb and LukM around parturition in serum as well as the site of infection, i.e. in colostrum and milk, compared to natural exposure to S. aureus. This study showed that it is practically feasible to vaccinate S. aureus naïve cattle and that experimental immunization induced a humoral immune response that differed from that after natural exposure only.

An airway epithelial IL-17A response signature identifies a steroid-unresponsive COPD patient subgroup

An airway epithelial IL-17A response signature identifies a steroid-unresponsive COPD patient subgroup

An airway epithelial IL-17A response signature identifies a steroid-unresponsive COPD patient subgroup.

BACKGROUND. Chronic obstructive pulmonary disease (COPD) is a heterogeneous smoking-related disease characterized by airway obstruction and inflammation. This inflammation may persist even after smoking cessation and responds variably to corticosteroids. Personalizing treatment to biologically similar “molecular phenotypes” may improve therapeutic efficacy in COPD. IL-17A is involved in neutrophilic inflammation and corticosteroid resistance, and thus may be particularly important in a COPD molecular phenotype.METHODS. We generated a gene expression signature of IL-17A response in bronchial airway epithelial brushings from smokers with and without COPD (n = 238), and validated it using data from 2 randomized trials of IL-17 blockade in psoriasis. This IL-17 signature was related to clinical and pathologic characteristics in 2 additional human studies of COPD: (a) SPIROMICS (n = 47), which included former and current smokers with COPD, and (b) GLUCOLD (n = 79), in which COPD participants were randomized to placebo or corticosteroids.RESULTS. The IL-17 signature was associated with an inflammatory profile characteristic of an IL-17 response, including increased airway neutrophils and macrophages. In SPIROMICS the signature was associated with increased airway obstruction and functional small airways disease on quantitative chest CT. In GLUCOLD the signature was associated with decreased response to corticosteroids, irrespective of airway eosinophilic or type 2 inflammation.CONCLUSION. These data suggest that a gene signature of IL-17 airway epithelial response distinguishes a biologically, radiographically, and clinically distinct COPD subgroup that may benefit from personalized therapy.TRIAL REGISTRATION. ClinicalTrials.gov NCT01969344.FUNDING. Primary support from the NIH, grants K23HL123778, K12HL11999, U19AI077439, DK072517, U01HL137880, K24HL137013 and R01HL121774 and contracts HHSN268200900013C, HHSN268200900014C, HHSN268200900015C, HHSN268200900016C, HHSN268200900017C, HHSN268200900018C, HHSN268200900019C and HHSN268200900020C.