IL-17A Responses Research Articles

Abstract P395: Activated T cells from Bph/2 Mice Have an Attenuated Cytokine Response to a Polyclonal T Cell Activator Compared to T cells from Bpn/3 Mice

Numerous studies point to a role for the immune system in various animal models of hypertension. However, there is little known about the immune system of Bph/2 mice, a spontaneously hypertensive mouse model. To address this, the purpose of the current study was a comprehensive comparison of the cytokine response of activated T cells from Bph/2 mice and Bpn/3 normotensive controls. To implement this, we quantified cytokine secretion from cell supernatants from anti-CD3/anti-CD28-activated splenocytes derived from either Bph/2 mice or the normotensive Bpn/3 control mice. In comparison to Bph/2 mice, activated T cells from Bpn/3 mice secreted greater levels of cytokines including, IL-2, IL-3, IL-4, IL-5, IFNγ, GM-CSF, TNFβ and TNFα. We noticed a particularly marked discrepancy in Th17 cytokines where T cells from Bph/2 mice had little to no induction of IL-17F (0 ± 0 pg/ml), IL-21 (1.388 ± 1.388 pg/ml) and IL-22 (1.922 ± 0.633 pg/ml ) in comparison to T cells from Bpn/3 mice (IL-17F: 2.972 ± 1.525 pg/ml; IL-21: 16.48 ± 8.368 pg/ml; IL-22: 62.84 ± 15.94 pg/ml) which showed a measurable induction of these cytokines. Likewise, the IL-17A response was lower in T cells from Bph/2 mice (19.23 ± 5.576 pg/ml) compared to those from Bpn/3 mice (55.79 ± 11.32 pg/ml). There was also a notable disparity in the secretion of TNFβ where T cells from Bpn/3 mice (543.6 ± 175.8 pg/ml) showed a robust response versus the response of T cells from Bph/2 mice (20.64 ± 16.43 pg/ml), which was less than 10% than that of T cells from Bpn/3 mice. Interestingly, while T cells from Bph/2 mice had much lower induction of the signature Th2 cytokine, IL-4 (Bpn/3: 326.2 ± 59.18 pg/ml vs. Bph/2: 130.3 ± 21.58 pg/ml), there was little difference in IL-9 (Bpn/3: 12.9 ± 1.689 pg/ml vs. Bph/2: 19.06 ± 2.903 pg/ml), which is also associated with a Th2 response. We also found that Bph/2 mice had a diminished chemokine response as compared to T cells from Bpn/3 mice. Overall, the data suggest that polyclonally activated T cells from Bph/2 mice have a weaker cytokine/chemokine response as compared to T cells from Bpn/3 mice which may be due to an overall attenuated activation of T cells from Bph/2 mice.

Enhanced efficacy of BCG vaccine formulated in adjuvant is dependent on IL-17A expression

A new, more effective vaccine against tuberculosis (TB) is urgently needed to curtail the current TB problem. The only licensed vaccine, BCG, has been shown to have highly variable protective efficacy in several clinical trials ranging from zero to 80 % against TB disease. We have previously reported that BCG formulated in dimethyl dioctadecyl-ammonium bromide (DDA) with D-(+)-Trehalose 6,6′-Dibehenate (TDB) adjuvant (BCG + Adj) is significantly more protective than BCG alone following murine aerosol Mycobacterium tuberculosis infection. Here we investigate the immunological basis for this improved efficacy by examining expression of different immune markers and cytokines in the lungs of vaccinated mice after M. tuberculosis aerosol challenge. We found significantly greater numbers of pulmonary IL-17A-expressing CD4+ T cells in mice immunized with BCG+Adj as compared to nonvaccinated and BCG-immunized mice at one-month post-challenge and that the enhanced protection was abrogated in IL-17A-deficient mice. Furthermore, we found significantly higher levels of IL-17A, IL-12p40 and IL-33 expression in the lungs of BCG + Adj immunized animals relative to nonvaccinated mice after M. tuberculosis challenge. These results demonstrate that the DDA/TDB adjuvant increases expression of IL-17A in response to the BCG vaccine and that these augmented IL-17A levels enhance control of M. tuberculosis infection.

An IL-17A-centric response to Epstein-Barr virus DNA mediated by dendritic Cell-T cell interactions.

Introduction: The Epstein-Barr virus has been associated with a considerable number of autoimmune diseases. We have previously demonstrated that EBV DNA enhances the production of IL-17A, a pro-inflammatory cytokine, via endosomal Toll-like receptor signalling. Methods: We used RNA-seq to analyze the transcriptional profile of mouse immune cells treated with EBV DNA. Results: We observed that EBV DNA upregulates an IL-17A-centric network of mediators. Ensemble Gene Set Enrichment Analysis (EGSEA) showed enriched expression of sets involved in inflammatory responses including IFNγ and TNF-α-associated pathways as well as proinflammatory diseases. On the other hand, while macrophages and B cells were somewhat able to induce an IL-17A response from T cells to EBV DNA, they were less potent than dendritic cells. EBV virions were also capable of eliciting the production of inflammatory mediators from dendritic cell-T cell cultures largely mirroring responses to the viral DNA. Conclusions: Given the wide prevalence of EBV in the population, our analyses reveal a network of mediators and cell types that may serve as therapeutic targets in a large proportion of people affected by autoimmune diseases.

Intranasal delivery of Salmonella OMVs decorated with Chlamydia trachomatis antigens induces specific local and systemic immune responses

ABSTRACT Chlamydia trachomatis is an obligate intracellular pathogen responsible for the most prevalent bacterial sexually transmitted disease globally. The high prevalence of chlamydial infections underscores the urgent need for licensed and effective vaccines to prevent transmission in populations. Bacterial outer membrane vesicles (OMVs) have emerged as promising mucosal vaccine carriers due to their inherent adjuvant properties and the ability to display heterologous antigens. In this proof-of-concept study, we evaluated the immunogenicity of Salmonella OMVs decorated with C. trachomatis MOMP-derived CTH522 or HtrA antigens in mice. Following a prime-boost intranasal vaccination approach, two OMV-based C. trachomatis vaccines elicited significant humoral responses specific to the antigens in both systemic and vaginal compartments. Furthermore, we demonstrated strong antigen-specific IFN-γ and IL17a responses in splenocytes and cervical lymph node cells of vaccinated mice, indicating CD4+ Th1 and Th17 biased immune responses. Notably, the OMV-CTH522 vaccine also induced the production of spleen-derived CD8+ T cells expressing IFN-γ. In conclusion, these results highlight the potential of OMV-based C. trachomatis vaccines for successful use in future challenge studies and demonstrate the suitability of our modular OMV platform for intranasal vaccine applications.

In vitro stimulation with nontuberculous mycobacteria induced a stronger cytokine response in leukocytes isolated from individuals with latent tuberculosis compared to those isolated from active tuberculosis or cystic fibrosis patients

Mycobacterium tuberculosis and opportunistic environmental non-tuberculous mycobacteria (NTM) can cause severe infection. Why latent tuberculosis infection advances to active disease, and why some individuals with cystic fibrosis (CF) develop pulmonary infections with NTM is still poorly understood. The aim of this study was to investigate the effector function of peripheral blood mononuclear cells (PBMC) from individuals with active or latent tuberculosis, individuals with CF with or without pulmonary NTM-infection and healthy controls, by measuring cytokine response to in vitro stimulation with different species of NTMs. The cytokine concentrations of IL-17A, IL-22, IL-23, IL-10, IL12p70 and IFN-γ were measured in PBMC-culture supernatants after stimulation with NTMs. PBMCs from individuals with latent tuberculosis infection showed strong IL-17A, IL-22, and IFN-γ responses compared to individuals with active tuberculosis or CF. IL-10 production was low in both tuberculosis groups compared to the CF groups and controls. This study suggests that IL-17A and IL-22 might be important to keep tuberculosis in a latent phase and that individuals with CF with an ongoing NTM infection seem to have a low cytokine response.

T helper cell responses in adult diarrheal patients following natural infection with enterotoxigenic Escherichia coli are primarily of the Th17 type.

Infection with enterotoxigenic Escherichia coli (ETEC) gives rise to IgA antibodies against both the heat labile toxin (LT) and colonization factors (CFs), which are considered to synergistically protect against ETEC diarrhea. Since the development of ETEC-specific long lived plasma cells and memory B cells is likely to be dependent on T helper (Th) cells, we investigated if natural ETEC diarrhea elicits ETEC-specific Th cells and their relation to IgA responses. Th cell subsets were analyzed in adult Bangladeshi patients hospitalized due to ETEC diarrhea by flow cytometric analysis of peripheral blood mononuclear cells (PBMCs) isolated from blood collected day 2, 7, 30 and 90 after hospitalization as well as in healthy controls. The LT- and CF-specific Th responses were determined by analysis of IL-17A and IFN-γ in antigen stimulated PBMC cultures using ELISA. ETEC-specific IgA secreted by circulating antibody secreting cells (plasmablasts) were analyzed by using the antibodies in lymphocyte supernatants (ALS) ELISA-based method and plasma IgA was also measured by ELISA. ETEC patients mounted significant ALS and plasma IgA responses against LTB and CFs on day 7 after hospitalization. ETEC patients had significantly elevated proportions of memory Th cells with a Th17 phenotype (CCR6+CXCR3-) in blood compared to controls, while frequencies of Th1 (CCR6-CXCR3+) or Th2 (CCR6-CXCR3-) cells were not increased. Antigen stimulation of PBMCs revealed IL-17A responses to LT, most clearly observed after stimulation with double mutant heat labile toxin (dmLT), but also with LT B subunit (LTB), and to CS6 in samples from patients with LT+ or CS6+ ETEC bacteria. Some individuals also mounted IFN-γ responses to dmLT and LTB. Levels of LTB specific IgA antibodies in ALS, but not plasma samples correlated with both IL-17A (r=0.5, p=0.02) and IFN-γ (r=0.6, p=0.01) responses to dmLT. Our results show that ETEC diarrhea induces T cell responses, which are predominantly of the Th17 type. The correlations between IL-17A and IFN-g and intestine-derived plasmablast responses support that Th responses may contribute to the development of protective IgA responses against ETEC infection. These observations provide important insights into T cell responses that need to be considered in the evaluation of advanced ETEC vaccine candidates.

Single cell and spatial sequencing define processes by which keratinocytes and fibroblasts amplify inflammatory responses in psoriasis

The immunopathogenesis of psoriasis, a common chronic inflammatory disease of the skin, is incompletely understood. Here we demonstrate, using a combination of single cell and spatial RNA sequencing, IL-36 dependent amplification of IL-17A and TNF inflammatory responses in the absence of neutrophil proteases, which primarily occur within the supraspinous layer of the psoriatic epidermis. We further show that a subset of SFRP2+ fibroblasts in psoriasis contribute to amplification of the immune network through transition to a pro-inflammatory state. The SFRP2+ fibroblast communication network involves production of CCL13, CCL19 and CXCL12, connected by ligand-receptor interactions to other spatially proximate cell types: CCR2+ myeloid cells, CCR7+LAMP3+ dendritic cells, and CXCR4 expressed on both CD8+ Tc17 cells and keratinocytes, respectively. The SFRP2+ fibroblasts also express cathepsin S, further amplifying inflammatory responses by activating IL-36G in keratinocytes. These data provide an in-depth view of psoriasis pathogenesis, which expands our understanding of the critical cellular participants to include inflammatory fibroblasts and their cellular interactions.

Topical histone deacetylase 1 inhibitor Entinostat ameliorates psoriasiform dermatitis through suppression of IL-17A response

BackgroundBiologics against IL-17A, IL-23 and TNF-α achieve a great success in treating psoriasis. However, the majority of patients still have some residual lesions left and require combination therapy to reach complete clearance. Topical medicine is an optional choice but only has limited categories. Besides, drug resistance is very often. Thus, topical medicine targeting new signaling pathway is still in an urgent need in the biologics era. ObjectiveTo investigate the role of topical Entinostat, a selective inhibitor of histone deacetylases 1 (HDAC1) that has been tested in clinic trials to treat solid tumors and hematological malignancies, in psoriasis therapy. MethodsEfficacious Entinostat were tested in a mouse imiquimod (IMQ)-induced psoriasiform dermatitis (PsD) model. An in vitro model consisting of human CD4 + T cell, murine T cells and NHEKs were used to screen Entinostat for inhibition of cutaneous inflammatory genes. ResultsTopical application of Entinostat significantly improved psoriasiform inflammation in imiquimod-induced mice model with great reduction of IL-17A+ γδT cell infiltration in skin. Entinostat is powerful agent in inhibition of Th17 cell generation and the expression of psoriasis-related inflammatory mediators by primary keratinocytes upon CD4+ T cells stimulation. ConclusionOur findings suggest Entinostat is a promising topical medicine for psoriasis treatment.

TLR2 in γδ T cells is required for metabolic support of their IL-17A response to a commensal bacterium on the ocular surface

Abstract The ocular surface is colonized by commensal microbiota, which tune the local mucosal immune response. We previously identified an ocular surface commensal, Corynebacterium mastitidis (C. mast), which induced IL-17A production from γδ T cells in the conjunctiva and eye-draining lymph nodes (DLN), and enhanced host resistance to fungal and bacterial pathogens. To elucidate how IL-17A producing γδ T cells (γδT17) are activated by C. mast, we associated WT and TLR2−/− mice with C. mast, and investigated the role of TLR2 in this process. This was based on the rationale that C. mastis a Gram-positive bacterium and that TLR2 expression on γδT cells increased after C. mast association. Mechanistic studies showed that TLR2 expression was required not only on DCs (for IL-1 production) but also on the γδT cells. RNA-Seq revealed that genes related to mitochondrial oxidative phosphorylation were dysregulated in TLR2−/− γδT17 cells, indicating that engagement of TLR2 may regulate metabolic processes in γδT17 cells. Seahorse assay confirmed that TLR2−/− γδ T17 cells displayed impaired oxygen consumption rates and lower ATP production. Interestingly, lysosomal activity, which plays a central role in cellular metabolism, was decreased in TLR2−/− γδ T17 cells. Enhancement of lysosomal activity by curcumin C1 restored ATP generation in TLR2−/− γδ T17 cells. We propose that intrinsic TLR2 signaling in γδ T cells is required for metabolic support of their IL-17A response.

Regulatory T cells limit opportunistic colonization of Staphylococcus aureusto promote lesion resolution in cutaneous leishmaniasis

Abstract The severity and responsiveness to treatment in L. braziliensis patients is influenced by a variety of factors, including microbiota and cytolytic T cells. Recently, we studied the skin microbiome in patients and demonstrated that high levels of S. aureus are associated with delayed healing in patients. To understand how S. aureus might influence cutaneous leishmaniasis, we studied the immune responses in mice following colonization with a S. aureus isolate from a L. braziliensis patient. Colonization of the skin with S. aureus alone induced a dominant type-17 response as well as an accumulation of Foxp3 T regulatory cells, and subsequent infection of mice with L. braziliensis led to increased IL-17 dependent pathology. Unexpectedly, transient depletion of total Tregs or RORγtin Foxp3 Tregs in S. aureus colonized mice increased IFN-γ and decreased the IL-17A response in skin. These mice exhibited increased pathology, which was accompanied by epidermal cell death and loss of barrier integrity. Additionally, the mice had substantially more S. aureus in the skin, and in the lymph nodes. In mice colonized with S. aureus and infected with L. braziliensis partial reduction led to a substantial increase in disease and a higher burden of S. aureus. Consistent with these results, in a transcriptional analysis of lesions from L. braziliensis patients, we found that low Foxp3 expression in patients had increased expression of cytolytic genes and IFN-γ, increased S. aureus in the lesions and had a delay in lesion resolution compared to patients with high Foxp3. Taken, together, these results suggest that in L. braziliensis patients Tregs are critical to regulate type-1 responses that in the context of S. aureus can promote more severe disease.

Bronchial epithelial cell transcriptome shows endotype heterogeneity of asthma in patients with NSAID-exacerbated respiratory disease

Nonsteroidal anti-inflammatory drugs-exacerbated respiratory disease (N-ERD) is currently classified as a type-2 (T2) immune-mediated disease characterized by asthma, chronic rhinosinusitis, and hypersensitivity to cyclooxygenase-1 inhibitors. The aim of this study was to characterize immunological endotypes of N-ERD based on the gene expression profile in the bronchial epithelium. mRNA transcriptome (mRNA-sequencing) was analyzed in bronchial brushings from patients with N-ERD (n=22), those with nonsteroidal anti-inflammatory drug-tolerant asthma (NTA, n= 21), and control subjects (n=11). Additionally, lipid and protein mediators were measured in bronchoalveolar lavage fluid (BALF). Initial analysis of the entire asthma group revealed 2 distinct gene expression signatures: "T2-high" with increased expression of T2-related genes (eg, CLCA1, CST1), and "proinflammatory" characterized by the expression of innate immunity (eg, FOSB, EGR3) and IL-17A response genes. These endotypes showed similar prevalence in N-ERD and NTA (eg, T2-high: 33% and 32%, respectively). T2-high asthma was characterized by increased expression of mast cell and eosinophil markers, goblet cell hyperplasia, and elevated LTE4 and PGD2 in BALF. Patients with a proinflammatory endotype showed mainly neutrophilic inflammation and increased innate immunity mediators in BALF. Furthermore, the proinflammatory signature was associated with a more severe course of asthma and marked airway obstruction. These signatures could be recreated invitro by exposure of bronchial epithelial cells to IL-13 (T2-high) and IL-17A (proinflammatory). T2-high signature was found only in one-third of patients with N-ERD, which was similar to what was found in patients with NTA. The proinflammatory endotype, which also occurred in N-ERD, suggests a novel mechanism of severe disease developing on a non-T2 background.

Bystander activation of tissue-resident memory CD4 T cells: Getting by with a little help from unfamiliar T-cell friends.

Reexposure to a pathogen triggers the activation of memory T cells that have already encountered a similar microbe. These long-lived CD4 T cells either circulate through the blood and tissues or reside within organs and are referred to as tissue-resident T cells (CD4 TRM ). In the current issue of the European Journal of Immunology [Eur. J. Immunol. 2023. 53: 2250247] issue, Curham etal. found that tissue-resident memory CD4 T cells in the lung and nasal tissues can respond to noncognate immune challenges. CD4 TRM cells, which were formed in response to Bordetella pertussis, proliferated and produced IL-17A in response to a secondary challenge with heat-killed Klebsiella pneumonia or lipopolysaccharide (LPS). This bystander response depends on the presence of dendritic cells that provide inflammatory cytokines. Furthermore, post K. pneumonia, intranasal immunization with whole cell pertussis vaccine reduced bacterial burden in the nasal tissue in a CD4 T-cell-dependent manner. The study indicates that the noncognate activation of TRM may serve as an innate-like immune response that rapidly develops before establishing a new pathogen-specific adaptive immune response.

Bystander activation of Bordetella pertussis-induced nasal tissue-resident memory CD4 T cells confers heterologous immunity to Klebsiella pneumoniae.

Tissue-resident memory CD4 T (TRM ) cells induced by infection with Bordetella pertussis persist in respiratory tissues and confer long-term protective immunity against reinfection. However, it is not clear how they are maintained in respiratory tissues. Here, we demonstrate that B. pertussis-specific CD4 TRM cells produce IL-17A in response to in vitro stimulation with LPS or heat-killed Klebsiella pneumoniae (HKKP) in the presence of dendritic cells. Furthermore, IL-17A-secreting CD4 TRM cells expand in the lung and nasal tissue of B. pertussis convalescent mice following in vivo administration of LPS or HKKP. Bystander activation of CD4 TRM cells was suppressed by anti-IL-12p40 but not by anti-MHCII antibodies. Furthermore, purified respiratory tissue-resident, but not circulating, CD4 T cells from convalescent mice produced IL-17A following direct stimulation with IL-23 and IL-1β or IL-18. Intranasal immunization of mice with a whole-cell pertussis vaccine induced respiratory CD4 TRM cells that were reactivated following stimulation with K. pneumoniae. Furthermore, the nasal pertussis vaccine conferred protective immunity against B. pertussis but also attenuated infection with K. pneumoniae. Our findings demonstrate that CD4 TRM cells induced by respiratory infection or vaccination can undergo bystander activation and confer heterologous immunity to an unrelated respiratory pathogen.

P064 High intestinal Secretory Leukocyte Protease Inhibitor (SLPI) expression correlates with abundant neutrophilic inflammation and identifies Inflammatory Bowel Disease patients with a strong IL-17 response.

Abstract Background Inflammatory bowel disease, comprising Crohn’s disease (CD) and ulcerative colitis (UC), is driven by aberrant host-microbial immune interactions. Disease heterogeneity and severity hamper effective treatment, thus new therapeutic strategies tailored to the patient’s underlying immune defect are required. In mice, upon epithelial barrier breach and microbiota driven inflammation, colonic intestinal epithelial cells increase Secretory Leukocyte Protease Inhibitor (SLPI) expression. SLPI can exert anti-microbial activity and inhibit NF-kB activation. Therefore, we hypothesized that SLPI expression is increased in the intestine of IBD patients and may differentiate a subgroup of patients with a distinctive underlying immune disease. Methods Intestinal biopsies and plasma from therapy-naive pediatric patients (age 6-18) with CD (n=41), UC (n=22) or IBD-negative controls (n=15) were collected. Intestinal SLPI protein was detected by immunohistochemistry (IHC), scored semi-quantitatively, and patients were dichotomized into ‘SLPI-high’ and ‘SLPI-low’ groups. RNA sequencing and quantitative PCR (qPCR) were performed. Plasma protein concentrations were assessed with Olink technology®. Results We observed increased SLPI mRNA and protein expression in intestinal tissue of CD and UC patients, compared to IBD-negative controls. Expression was the strongest in macroscopically inflamed tissue and more dominant in colon than in small intestinal ileum. Colonic SLPI expression was associated with endoscopic severity of inflammation, with histologic disease activity, and with clinical disease activity in CD and UC patients. Furthermore, high epithelial SLPI expression associated with abundant neutrophil infiltration and calprotectin expression. RNA-seq revealed that biopsies of SLPI-high patients had a signature of inflammatory neutrophilic inflammation including the genes OSM, IL-1B, and CXCL8, which have been associated with severe disease progression and resistance to anti-TNF treatment. Most notably, biopsies of SLPI-high patients had a signature of increased IL-17 signaling, which was supported by IHC detection of high frequencies of IL-17 producing cells in the paired biopsies and higher plasma concentrations of CCL20, MMP10 and IL-17A. Conclusion Together, these results demonstrate that intestinal SLPI expression identifies severe IBD patients with high intestinal SLPI expression and immune features of therapy resistance, who have increased IL-17A responses and subsequent neutrophilic inflammation compared to SLPI-low patients. As such, epithelial SLPI expression is a histological parameter that could support tailored treatment strategies in pediatric IBD patients at the time of diagnosis.

The trehalose glycolipid C18Brar promotes antibody and T-cell immune responses to Mannheimia haemolytica and Mycoplasma ovipneumoniae whole cell antigens in sheep.

Bronchopneumonia is a common respiratory disease in livestock. Mannheimia haemolytica is considered the main causative pathogen leading to lung damage in sheep, with Mycoplasma ovipneumoniae and ParaInfluenza virus type 3, combined with adverse physical and physiological stress, being predisposing factors. A balance of humoral and cellular immunity is thought to be important for protection against developing respiratory disease. In the current study, we compared the ability of the trehalose glycolipid adjuvant C18Brar (C18-alkylated brartemicin analogue) and three commercially available adjuvant systems i.e., Quil-A, Emulsigen-D, and a combination of Quil-A and aluminium hydroxide gel, to stimulate antibody and cellular immune responses to antigens from inactivated whole cells of M. haemolytica and M. ovipneumoniae in sheep. C18Brar and Emulsigen-D induced the strongest antigen-specific antibody responses to both M. haemolytica and M. ovipneumoniae, while C18Brar and Quil-A promoted the strongest antigen-specific IL-17A responses. The expression of genes with known immune functions was determined in antigen-stimulated blood cultures using Nanostring nCounter technology. The expression levels of CD40, IL22, TGFB1, and IL2RA were upregulated in antigen-stimulated blood cultures from animals vaccinated with C18Brar, which is consistent with T-cell activation. Collectively, the results demonstrate that C18Brar can promote both antibody and cellular responses, notably Th17 immune responses in a ruminant species.

Mycobacterium avium subsp. paratuberculosis antigens induce cellular immune responses in cattle without causing reactivity to tuberculin in the tuberculosis skin test.

Mycobacterium avium subspecies paratuberculosis (MAP) causes chronic progressive granulomatous enteritis leading to diarrhea, weight-loss, and eventual death in ruminants. Commercially available vaccine provides only partial protection against MAP infection and can interfere with the use of current diagnostic tests for bovine tuberculosis in cattle. Here, we characterized immune responses in calves to vaccines containing four truncated MAP antigens as a fusion (Ag85A202-347-SOD1-72-Ag85B173-330-74F1-148+669-786), either displayed on protein particles, or expressed as a soluble recombinant MAP (rMAP) fusion protein as well as to commercially available Silirum® vaccine. The rMAP fusion protein elicited the strongest antigen-specific antibody responses to both PPDA and recombinant antigen and strong and long-lasting T-cell immune responses to these antigens, as indicated by increased production of IFN-γ and IL-17A in antigen-stimulated whole blood cultures. The MAP fusion protein particle vaccine induced minimal antibody responses and weak IFN-γ responses but stimulated IL-17A responses to recombinant antigen. The immune response profile of Silirum® vaccine was characterized by weak antibodies and strong IFN-γ and IL-17A responses to PPDA. Transcription analysis on antigen-stimulated leukocytes from cattle vaccinated with rMAP fusion protein showed differential expression of several immune response genes and genes involved in costimulatory signaling, TLR4, TLR2, PTX3, PTGS2, PD-L1, IL1B, IL2, IL6, IL12B, IL17A, IL22, IFNG, CD40, and CD86. Moreover, the expression of several genes of immune pathways correlated with cellular immune responses in the rMAP fusion protein vaccinated group. These genes have key roles in pathways of mycobacterial immunity, including autophagy, manipulation of macrophage-mediated killing, Th17- and regulatory T cells- (Treg) mediated responses. Calves vaccinated with either the rMAP fusion protein or MAP fusion protein particle vaccine did not induce reactivity to PPDA and PPDB in a comparative cervical skin test, whereas Silirum® induced reactivity to these tuberculins in most of the vaccinated animals. Overall, our results suggest that a combination of recombinant MAP antigens in the form of a soluble fusion protein vaccine are capable of inducing strong antigen-specific humoral and a balanced Th1/Th17-cell immune response. These findings, together with the absence of reactivity to tuberculin, suggest this subunit vaccine could provide protective immunity against intracellular MAP infection in cattle without compromising the use of current bovine tuberculosis surveillance test.

003 Interleukin (IL)-26 drives pathogenic IL-17A responses through a TH17-keratinocyte crosstalk

Interleukin (IL)-26 is a TH17 cytokine with known antimicrobial and pro-inflammatory functions and is highly expressed in tissues of TH17-mediated inflammatory diseases including psoriasis. However, the expression of IL-26 with respect to IL-17A and its precise function in the context of pathogenic TH17 responses are still unclear. In this study, we used flow cytometry-based fluorescent in situ hybridization of blood TH17 cells along with single-cell and spatial transcriptomics of psoriatic skin lesions to analyze the dynamic of the regulation of IL-26 expression in TH17 cells. We show that blood TH17 cells contain a large population of IL-26-producing cells that do not produce IL-17A. Unlike IL-17A-producing cells, these IL-26-producing cells develop at early stages of TH17 differentiation and do not require TGF-β. However, when exposed to TGF-β, IL-26-producing cells transition into IL-17 producers, a process also observed in psoriatic skin lesions, where TGF-β is highly expressed by basal keratinocytes in close vicinity to IL-26-producing T cells. T cell-derived IL-26 was able to induce TGF-β expression in keratinocytes themselves, suggesting a mechanism by which TH17 cells control IL-17A responses in tissues via the expression of IL-26. Thus, our study identifies IL-26-producing cells as an early differentiation stage of TH17 cells that can further differentiate into IL-17A producing cells upon tissues infiltration via a paracrine loop involving TGF-β.

Helminth species dependent effects on Th1 and Th17 cytokines in active tuberculosis patients and healthy community controls.

Despite that the impact of different helminth species is not well explored, the current dogma states that helminths affect the Th1/Th2 balance which in turn affects the risk of tuberculosis (TB) reactivation and severity of disease. We investigated the influence of helminth species on cytokine profiles including IL-17A in TB patients and healthy community controls (CCs). In total, 104 newly diagnosed pulmonary TB patients and 70 HIV negative and QuantiFERON negative CCs in Gondar, Ethiopia were included following helminth screening by stool microscopy. Plasma samples and ex vivo stimulation of peripheral blood mononuclear cells (PBMCs) with purified protein derivative (PPD) and Staphylococcus enterotoxin B (SEB) was used to determine cytokine profiles by cytometric bead array. In CCs, Ascaris lumbricoides or Schistosoma mansoni infections were associated with an impaired Th1-type response (IFN-gamma, IL-6 and TNF-alpha) in PBMCs mainly with SEB stimulations, whereas in TB patients only hookworm infection showed a similar pattern. Among CCs, the IL-17A response in PBMCs stimulated with SEB was higher only for S. mansoni, whereas in TB patients, the elevated systemic IL-17A plasma level was significantly suppressed in hookworm infected TB patients compared to patients without helminth coinfection. Following treatment of TB and helminth infection there was a general decrease in ex vivio IL-10 and TNF-alpha production in unstimulated, PPD or SEB stimulated PBMCs that was the most pronounced and significant in TB patients infected with S. mansoni, whereas the follow-up levels of IFN-gamma and IL-17A was significantly increased only in TB patients without helminth coinfection from PBMCs stimulated mainly with SEB. In summary, in addition to confirming helminth specific effects on the Th1/Th2 response before and after TB treatment, our novel finding is that IL-17A was impaired in helminth infected TB patients especially for hookworm, indicating a helminth species-specific immunoregulatory effect on IL-17A which needs to be further investigated.

Vaccine protection by Cryptococcus neoformans Δsgl1 is mediated by γδ T cells via TLR2 signaling

We previously reported that administration of Cryptococcus neoformans Δsgl1 mutant vaccine, accumulating sterylglucosides (SGs) and having normal capsule (GXM), protects mice from a subsequent infection even during CD4+ T cells deficiency, a condition commonly associated with cryptococcosis. Here, we studied the immune mechanism that confers host protection during CD4+T deficiency. Mice receiving Δsgl1 vaccine produce IFNγ and IL-17A during CD4+ T (or CD8+ T) deficiency, and protection was lost when either cytokine was neutralized. IFNγ and/or IL-17A are produced by γδ T cells, and mice lacking these cells are no longer protected. Interestingly, ex vivo γδ T cells are highly stimulated in producing IFNγ and/or IL-17A by Δsgl1 vaccine, but this production was significantly decreased when cells were incubated with C. neoformans Δcap59/Δsgl1 mutant, accumulating SGs but lacking GXM. GXM modulates toll-like receptors (TLRs), including TLR2. Importantly, neither Δsgl1 nor Δcap59/Δsgl1 stimulate IFNγ or IL-17A production by ex vivo γδ T cells from TLR2−/− mice. Finally, TLR2−/− animals do not produce IL-17A in response to Δsgl1 vaccine and were no longer protected from WT challenge. Our results suggest that SGs may act as adjuvants for GXM to stimulate γδ T cells in producing IFNγ and IL-17A via TLR2, a mechanism that is still preserved upon CD4+ T deficiency.

Signaling via dopamine and adenosine receptors modulate viral peptide-specific and T-cell IL-8 response in COVID-19

B-cell but not T-cell responses have been extensively studied using peripheral blood mononuclear cells (PBMCs) obtained from patients with coronavirus disease 2019 (COVID-19). Our recent study showed that not only T-helper (Th) 17 but also Th1 cells directly produce interleukin (IL)-8, a major source of neutrophilic inflammation, which is also known to induce disseminated intravascular coagulation (DIC) in COVID-19 patients. Neutrophilic inflammation caused by IL-17A or IL-8 can be fatal; thus, therapeutic intervention is highly expected. The present study aimed to investigate the T-cell responses in the Japanese patients. We synthesized spike protein-derived 15-mer peptides that are expected to bind to HLA class II allelic products frequently observed in the Japanese population, and checked the T-cell responses in Japanese patients with COVID-19. We have found that (i) patients show marked IL-8 but not IL-17A responses; (ii) these responses are restricted by HLA-DR; and (iii) IL-8 responses are abrogated by a dopamine D2 like receptor (D2R) agonist, ropinirole, and an adenosine A2a receptor (A2aR) antagonist, istradefylline. Compounds used for the treatment of Parkinson’s disease may ease DIC in COVID-19. (183 words)