IL‐22 neutralizing autoantibodies impair fungal clearance in murine oropharyngeal candidiasis model

Protection against mucocutaneous candidiasis depends on the T helper (Th)17 pathway, as gene defects affecting its integrity result in inability to clear Candida albicans infection on body surfaces. Moreover, autoantibodies neutralizing Th17 cytokines have been related to chronic candidiasis in a rare inherited disorder called autoimmune polyendocriopathy candidiasis ectodermal dystrophy (APECED) caused by mutations in autoimmune regulator (AIRE) gene. However, the direct pathogenicity of these autoantibodies has not yet been addressed. Here we show that the level of anti‐IL17A autoantibodies that develop in aged Aire‐deficient mice is not sufficient for conferring susceptibility to oropharyngeal candidiasis. However, patient‐derived monoclonal antibodies that cross‐react with murine IL‐22 increase the fungal burden on C. albicans infected mucosa. Nevertheless, the lack of macroscopically evident infectious pathology on the oral mucosa of infected mice suggests that additional susceptibility factors are needed to precipitate a clinical disease.     

Mucocutaneous candidiasis and autoimmunity against cytokines in APECED and thymoma patients: clinical and pathogenetic implications

Much has been learnt about the mechanisms of thymic self-tolerance induction from work on both the rare autosomal recessive disease autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) and the autoimmune regulator (AIRE) protein mutated in this disease. Normally, AIRE drives low-level expression of huge numbers of peripheral tissue-specific antigens (TSAgs) in medullary thymic epithelial cells (mTECs), leading to the deletion of TSAg-reactive thymocytes maturing nearby. The very recently discovered neutralizing autoantibodies (autoAbs) against Th17-related cells and cytokines in two autoimmunity-related syndromes associated with AIRE-mutant thymi or AIRE-deficient thymomas help to explain the chronic mucocutaneous candidiasis (CMC) seen in both syndromes. The surprising parallels between these syndromes also demand new hypotheses and research into the consequences of AIRE deficiency and the ensuing autoimmunizing pathways, and suggest more appropriate treatment regimens as discussed in this review.     

Introduction

Abstract

Autoimmune polyendocrinopathy – candidiasis – ectodermal dystrophy (APECED) is caused by mutations in the Autoimmune regulator (AIRE) gene and is associated with neutralizing anti-cytokine autoantibodies. We have used an in vivo challenge model to analyze antigen-specific CD4⁺ T cell responses. Bacille Calmette–Guérin (BCG)-vaccinated patients and controls were injected tuberculin intradermally, skin blisters were induced by suction on the indurations and on unexposed skin, and the infiltrating cells harvested. The patients had a quantitatively normal CD4⁺ T cell response and no significant abnormalities in the expression of T helper type (Th) 1- or Th2-related genes. The expression of interleukin (IL)-22, in contrast, was lower in the patients. Two patients, both with a pre-existing ocular keratopathy, experienced a relapse of keratoconjunctivitis, suggesting a possible immunological basis for this APECED component. Our in vivo data are compatible with a selective IL-22 defect in the activated CD4⁺ T cells of APECED patients, affecting also unexposed skin in steady-state conditions.     

Comparative and correlative assessments of cytokine,complement and antibody patterns in paediatric type 1 diabetes

One of the most widespread and effective environmental factors is the infection with enteroviruses (EVs) which accelerate β cell destruction in type 1 diabetes (T1D). This study represented a comparison between diabetic EV⁺ and EV^– children as well as correlation analysis between autoantibodies, T1D markers, cytokines, complement activation products and anti‐coxsackievirus (CV) immunoglobulin (Ig)G. EV RNA was detected in Egyptian children with T1D (26·2%) and healthy controls (0%). Detection of anti‐CV IgG in T1D‐EV⁺ resulted in 64% positivity. Within T1D‐EV⁺, previously diagnosed (PD) showed 74 versus 56% in newly diagnosed (ND) children. Comparisons between populations showed increased levels of haemoglobin A1c (HbA1c), C‐reactive protein (CRP), nitric oxide (NO), glutamic acid decarboxylase and insulin and islet cell autoantibodies [glutamic acid decarboxylase autoantibodies (GADA), insulin autoantibodies (IAA) and islet cell cytoplasmic autoantibodies (ICA), respectively], interferon (IFN)‐γ, tumour necrosis factor (TNF)‐α, interleukin (IL)‐1β, IL ?10, IL ?12, IL ?17, C3d and sC5–9 in T1D‐EV⁺ versus T1D‐EV^–. Conversely, both IL‐20 and transforming growth factor (TGF‐β) decreased in T1D‐EV⁺ versus EV^–, while IL‐4, ?6 and ?13 did not show any changes. Correlation analysis showed dependency of accelerated autoimmunity and β cell destruction on increased IFN‐γ, IL‐12 and IL‐17 versus decreased IL‐4, ?6 and ?13. In conclusion, IFN‐γ, IL‐12 and IL‐17 played an essential role in exacerbating EV⁺‐T1D, while C3d, sC5b ?9, IL‐10 and ?20 displayed distinct patterns.     

Autoantibodies to IL-17A may be Correlated with the Severity of Mucocutaneous Candidiasis in APECED Patients

The relative roles of various autoantibodies against IL-17-type cytokines in susceptibility to chronic mucocutaneous candidiasis (CMC) in patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) remain poorly defined. The purpose of this longitudinal study was to analyze the relationship between the occurrence of mucocutaneous candidiasis and levels of anti-IL-17A, anti-IL-17F and anti-IL-22 autoantibodies. We studied six APECED patients from four families with various disease manifestations. Clinical data were collected during regular follow-up. Anti-endocrine organ antibody levels and clinical chemistry and immunology parameters were determined in routine laboratory assays on freshly isolated serum. Levels of autoantibodies against IL-17A, IL-17F, IL-22, IFN-α, IFN-ω and TNF-α, and cytokine release by Candida-exposed blood cells were determined by ELISA. Mutations were analyzed by sequencing genomic DNA. Four patients carried the germline c.769C?>?T homozygous nonsense mutation, which results in R257X truncation of the AIRE protein, and two patients from the same family were compound heterozygous for the c.769C?>?T/c.1344delC mutation. We found persistently high levels of antibodies against IL-17A in the serum samples of one patient presenting CMC since infancy and low or undetectable anti-IL-17A antibody levels in the sera of five patients with no candidiasis or without severe candidiasis. By contrast, levels of autoantibodies against IL-17F and IL-22 were higher in all patients than in healthy controls. Release of IL-17-type cytokines by Candida-exposed blood mononuclear cells was low or negligible in all patients tested. We suggest that anti-IL-17A antibodies may play an important role in the predisposition to candidiasis of APECED patients. However, the lack of severe CMC in APECED patients with high levels of IL-17F and anti-IL-22 autoantibodies clearly calls into question the role of these antibodies as the principal cause of cutaneous and mucosal candidiasis in at least some APECED patients. These data also suggest that the impaired release of IL-17-type cytokines by blood cells may be an element of the immunopathology of CMC in APECED patients.     

Mitigated Tregs and Augmented Th17 Cells and Cytokines are Associated with Severity of Experimental Autoimmune Neuritis

Experimental autoimmune neuritis (EAN), an animal model of human Guillain–Barré syndrome, has long been considered as a T helper (Th) 1 cell–mediated autoimmune disorder. However, deficiency of IFN‐γ, a signature Th1 cytokine, aggravated EAN, with features of elevated production of IL‐17A, despite an alleviated systemic Th1 immune response. We hypothesized that Th17 cells and their cytokines might play a pathogenic role in EAN. To further clarify the roles of these Th and regulatory T cell (Treg) cytokines in the pathogenesis of EAN and their interrelationship, we investigated the expression of Th1/Th2/Th17/Treg cytokines in EAN in this study. We found that the levels of Th17 cells and IL‐17A in cauda equina (CE)‐infiltrating cells and splenic mononuclear cells (MNCs) as well as in serum paralleled the disease evolution, which increased progressively during the initiation stage and reached higher value at the peak of EAN. The same pattern was also noticed for the expression of IL‐22. The diverse expression profiles of FoxP3, IL‐17 receptors A and C were seen in CE‐infiltrating cells and splenic MNCs in EAN. These findings indicate a major pro‐inflammatory role of Th17 cells and IL‐17A in the pathogenesis of EAN. Therapeutic interventions may be focused upon inhibiting Th17 cells and their cytokines in the early phase of EAN, so as to delay and suppress clinical signs of the disease, which has relevance for future studies on pathogenesis and treatment of GBS in humans.     

The influence of regulatory T cells and diurnal hormone rhythms on T helper cell activity

Symptoms of diseases such as rheumatoid arthritis, which is T helper 1 (Th1) dependent, and asthma, which is T helper 2 (Th2) dependent, are influenced by diurnal rhythms and natural regulatory T cells (nTreg). However, the mechanisms responsible for the diurnal rhythm of disease activity have not been identified and it is unclear whether nTreg activity is diurnal rhythm‐dependent. We therefore investigated whether a 24‐hr diurnal cycle affected the ability of various helper T‐cell populations to generate immunomodulatory and pro‐inflammatory cytokines, as well as its suppression by nTreg cells. Using a within‐subject crossover design, sleep versus continuous wakefulness was compared over a 24‐hr period in healthy young volunteers under defined environmental conditions. Venous blood was drawn periodically every 5 hr and the function of T cells was explored in vitro. We demonstrated that interleukin (IL)‐2, interferon‐γ (IFN‐γ), tumour necrosis factor‐α (TNF‐α) and IL‐10 secretion by naïve CD4⁺ T cells follows a diurnal rhythm. Furthermore, multiple regression analysis, as well as subsequent in vitro experiments, suggested that serum levels of cortisol and prolactin are part of the underlying mechanism. Additionally, we observed that nTreg suppressed the secretion of IFN‐γ, IL‐2 and TNF‐α, but not the secretion of IL‐4, IL‐6, IL‐10 and IL‐17A. However, the abrogation of IL‐2 release was reversed upon inhibiting CD25 on nTreg. Highly purified nTreg secreted IL‐6, IL‐10 and IL‐17A, but not IL‐2, IL‐4, IFN‐γ or TNF‐α. Taken together, our results demonstrate that hormones and nTreg modulate the diurnal rhythm of T helper cell activity.     

Serum cytokine pattern in young children with screening detected coeliac disease

Coeliac disease is an autoimmune disease characterized by inflammation localized to the small bowel, but less is known about systemic signs of inflammation. The aim was to measure cytokines of the T helper 1 (Th1) and T helper 2 (Th2) cell patterns in children with screening‐detected coeliac disease before and after treatment with a gluten‐free diet. Serum samples selected before and after the start of a gluten‐free diet from 26 3‐year‐old children diagnosed with biopsy‐proven coeliac disease and from 52 matched controls were assayed in an multiplex enzyme‐linked immunosorbent assay (ELISA) for the 10 cytokines: interferon (IFN)‐γ, interleukin (IL)‐1β, IL‐2, IL‐4, IL‐5, IL‐8, IL‐10, IL‐12p70, IL‐13 and tumour necrosis factor (TNF)‐α. Among Th1 cytokines, IFN‐γ and IL‐12p70 were elevated significantly in children with coeliac disease compared to controls (P < 0·001 and P = 0·001, respectively). Similar findings were demonstrated for the Th2 cytokines IL‐5 (P < 0·001), IL‐10 (P = 0·001) and IL‐13 (P = 0·002). No difference in cytokine levels between the two groups was found for TNF‐α, IL‐1β, IL‐2, IL‐4 and IL‐8. After gluten‐free diet, levels of IL‐5, IL‐12 and IL‐10 decreased significantly (P < 0·001, P = 0·002 and P = 0·007) and IFN‐γ levels were reduced (P = 0·059). Young children with coeliac disease detected by screening demonstrate elevated levels of serum cytokines at time of diagnosis. A prolonged systemic inflammation may, in turn, contribute to long‐term complications known to be associated with untreated coeliac disease.     

Effects of Pregnancy‐associated Malaria on T Cell Cytokines in Cameroonian Women

Although Th17 cells subsets improve immunity against extra and intracellular pathogens, and in modulating Th1 and other immune responses, its role on pregnancy‐associated malaria (PAM) is unknown. This study aims to investigate the effects of PAM on Th1 (IFN‐γ, TNF‐α), IL‐10 family (IL‐10, IL‐19, IL‐22), Th17 (IL‐17A, IL‐23) cytokines and on CXCL‐10 chemokine profiles in pregnant women. Between 2010 and 2011, venous blood specimens from 107 volunteer pregnant Cameroonian women was used to determine parasitaemia microscopically and haemoglobin levels using HemoCue analyzer. Plasma levels of the biomarkers were determined by ELISA. Parasitaemia was higher in women with low haemoglobin levels, parity and mother's age. IL‐10 and CXCL‐10 plasma levels were higher in the malaria infected and in anaemic women while IFN‐γ and IL‐17A levels were higher in malaria non‐infected and in non‐anaemic women. Parasitaemia correlated positively with IL‐10 and CXCL‐10 levels but inversely with IFN‐γ and IL‐17A. Haemoglobin levels were higher in women with low IL‐10 and CXCL‐10 levels, and in group with high IFN‐γ, IL‐17A and IL‐23 levels. Only IL‐10 levels associated negatively with parity. Positive correlations were observed between Th17 (IL‐17A) and Th1 (IFN‐γ, TNF‐α), IL‐10 family (IL‐19 and IL‐22) and Th17 (IL‐23) cytokines. Multivariate analysis showed association between: mother's age and IFN‐γ levels, parasitaemia and IL‐10 and CXCL‐10 levels and haemoglobin levels, gestational age and IL‐17A levels. In conclusion, during PAM, CXCL‐10 and IL‐10 responses are implicated in the pathogenesis while Th17 and Th1 immune responses, via IL‐17A and IFN‐γ might play protective roles.     

Comparative analysis of autoantibodies targeting peptidylarginine deiminase type 4, mutated citrullinated vimentin and cyclic citrullinated peptides in rheumatoid arthritis: associations with cytokine profiles,clinical and genetic features

Antibodies against cyclic citrullinated peptides (anti‐CCP) are widely used for diagnosis of rheumatoid arthritis (RA). We performed a comparative analysis of antibodies targeting the citrullinating enzyme peptidylarginine deiminase type 4 (anti‐PAD4) and mutated citrullinated vimentin (anti‐MCV) with anti‐CCP autoantibodies in RA patients and examined their relationships with clinical parameters, cytokine profiles and the PADI4 gene. Autoantibodies were examined by enzyme‐linked immunosorbent assay (ELISA) in sera of 170 RA patients and 103 controls. Cytokine profiles were measured using a multiplex system. PADI4 polymorphisms (89G > A, 90T > C and 92G > C) were genotyped by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). Anti‐PAD4, anti‐MCV and anti‐CCP autoantibodies were detected in 24, 61 and 74% of RA patients, respectively. Positive correlations were observed between anti‐PAD4 and disease duration; anti‐CCP and erythrocyte sedimentation rate (ESR); anti‐MCV and ESR and C‐reactive protein. Anti‐MCV antibodies were associated with high disease activity score 28 (DAS‐28) in early RA. Concentrations of T helper type 1 (Th1) [tumour necrosis factor (TNF)‐α, interleukin (IL)‐12, IL‐2, IL‐1β], Th2 (IL‐4, IL‐6, IL‐10, IL‐13) and Th17 (IL‐17) cytokines were higher in RA than in controls. Th2 and, to a lesser extent, Th1‐related cytokines, showed positive correlations with anti‐MCV and anti‐CCP. The GTG haplotype in PADI4 was associated with anti‐CCP and anti‐MCV, but not anti‐PAD4 antibodies. In conclusion, anti‐PAD4 antibodies are detected mainly in established RA, which is in contrast to the early detection of antibodies against citrullinated peptide/proteins (ACPAs). Among autoantibodies, anti‐MCV appear to perform better as markers of disease activity. Furthermore, anti‐CCP and anti‐MCV are associated genetically with the citrullinating enzyme PAD4 and are related strongly to Th1 and Th2 cytokines, suggesting a feed‐forward loop between cytokines and ACPA production.     

Excessive CD4+ T cells co-expressing interleukin-17 and interferon-γ in patients with Behçet's disease

Excessive T helper type 1 (Th1) cell activity has been reported in Behçet's disease (BD). Recently, association of Th17 cells with certain autoimmune diseases was reported, and we thus investigated circulating Th17 cells in BD. CD4⁺CD45RO^– (naive) T cells were cultured with Th0‐, Th1‐, Th2‐ and Th17‐related cytokines and antibodies, and their mRNA was studied by real‐time polymerase chain reaction (PCR). When naive CD4⁺ T cells were cultured with Th1‐ and Th17‐related cytokines, interferon (IFN)‐γ mRNA and interleukin (IL)‐17 mRNA were up‐regulated, respectively, in BD patients. Naive CD4⁺ T cells cultured in a Th17 cell‐inducing condition expressed IL‐23 receptor (IL‐23R) mRNA excessively. IL‐17 mRNA expression was induced only when naive CD4⁺T cells were cultured in the presence of IL‐23. CD4⁺ T cells cultured with Th17 cytokines expressed excessive RAR‐related orphan receptor C (RORC) mRNA. Using intracellular cytokine staining, we found that CD45RO⁺(memory) CD4⁺ T cells producing IL‐17 and IFN‐γ simultaneously were increased significantly. Memory CD4⁺ T cells producing IFN‐γ but not IL‐17 decreased profoundly in BD patients. CD4⁺ T cells producing IL‐17 and IFN‐γ simultaneously were found in BD skin lesions. Collectively, we found excessive CD4⁺ T cells producing IL‐17 and IFN‐γ (Th1/Th17) cells in patients with BD, and possible involvement of IL‐23/IL‐23R pathway for the appearance of excessive Th1/Th17 cells.     

Induction, function and regulation of IL-17-producing T cells

Recent reports have provided convincing evidence that IL‐17‐producing T cells play a key role in the pathogenesis of organ‐specific autoimmune diseases, a function previously attributed exclusively to IFN‐γ‐secreting Th1 cells. Furthermore, it appears that IL‐17‐producing T cells can also function with Th1 cells to mediate protective immunity to pathogens. Although much of the focus has been on IL‐17‐secreting CD4⁺ T cells, termed Th17 cells, CD8⁺ T cells, γδ T cells and NKT cells are also capable of secreting IL‐17. The differentiation of Th17 cells from naïve T cells appears to involve signals from TGF‐β, IL‐6, IL‐21, IL‐1β and IL‐23. Furthermore, IL‐1α or IL‐1β in synergy with IL‐23 can promote IL‐17 secretion from memory T cells. The induction or function of Th17 cells is regulated by cytokines secreted by the other major subtypes of T cells, including IFN‐γ, IL‐4, IL‐10 and at high concentrations, TGF‐β. The main function of IL‐17‐secreting T cells is to mediate inflammation, by stimulating production of inflammatory cytokines, such as TNF‐α, IL‐1β and IL‐6, and inflammatory chemokines that promote the recruitment of neutrophils and macrophages.     

Modified vaccinia Ankara‐expressing Ag85A,a novel tuberculosis vaccine,is safe in adolescents and children,and induces polyfunctional CD4+ T cells

Modified vaccinia Ankara‐expressing Ag85A (MVA85A) is a new tuberculosis (TB) vaccine aimed at enhancing immunity induced by BCG. We investigated the safety and immunogenicity of MVA85A in healthy adolescents and children from a TB endemic region, who received BCG at birth. Twelve adolescents and 24 children were vaccinated and followed up for 12 or 6 months, respectively. Adverse events were documented and vaccine‐induced immune responses assessed by IFN‐γ ELISpot and intracellular cytokine staining. The vaccine was well tolerated and there were no vaccine‐related serious adverse events. MVA85A induced potent and durable T‐cell responses. Multiple CD4⁺ T‐cell subsets, based on expression of IFN‐γ, TNF‐α, IL‐2, IL‐17 and GM‐CSF, were induced. Polyfunctional CD4⁺ T cells co‐expressing IFN‐γ, TNF‐α and IL‐2 dominated the response in both age groups. A novel CD4⁺ cell subset co‐expressing these three Th1 cytokines and IL‐17 was induced in adolescents, while a novel CD4⁺ T‐cell subset co‐expressing Th1 cytokines and GM‐CSF was induced in children. Ag‐specific CD8⁺ T cells were not detected. We conclude that in adolescents and children MVA85A safely induces the type of immunity thought to be important in protection against TB. This includes induction of novel Th1‐cell populations that have not been previously described in humans.     

Decreased Plasma IL‐22 Levels and Correlations with IL‐22‐Producing T Helper Cells in Patients with New‐Onset Systemic Lupus Erythematosus

Interleukin‐22 (IL‐22) and IL‐22‐producing T helper (Th) cells are involved in the pathogenesis of autoimmune diseases. However, the roles of IL‐22 and IL‐22‐producing T helper cells in systemic lupus erythematosus (SLE) remain unclear. Plasma levels of IL‐22 were measured in 41 patients with SLE (19 new‐onset and 22 relapsing patients) and 20 healthy controls by enzyme‐linked immunosorbent assay (ELISA). Meanwhile, the percentages of CD4⁺IFN‐γ⁺ (Th1), CD4⁺IL‐17⁺ (Th17) and CD4⁺IFN‐γ^?IL‐17^? IL‐22⁺ (Th22) cells in peripheral lymphocytes were determined by flow cytometry, and plasma IL‐22 autoantibodies were detected by ELISA in 19 new‐onset SLE patients and 20 healthy controls. Plasma IL‐22 levels in new‐onset SLE patients were significantly decreased compared with relapsing SLE patients and healthy controls. After treatment with prednisone and hydroxychloroquine, the levels of plasma IL‐22 in new‐onset SLE patients were obviously increased but still lower than healthy controls. There was a positive correlation between plasma IL‐22 levels and the percentages of Th22 cells, but not Th1 and Th17 cells. Moreover, plasma IL‐22 levels as well as peripheral Th17 and Th22 cells correlated with SLE disease activity index (SLEDAI) scores and erythrocyte sedimentation rate (ESR). High frequencies of plasma IL‐22 autoantibodies were detected in new‐onset SLE patients. However, IL‐22 levels did not correlate with IL‐22 autoantibody. Decreased plasma IL‐22 levels and correlation with Th22 cells may be distinct features in new‐onset SLE. Moreover, IL‐22 and Th22 cell correlated with SLE disease activity.     

Absence of Notch1 in murine myeloid cells attenuates the development of experimental autoimmune encephalomyelitis by affecting Th1 and Th17 priming

Inhibition of Notch signalling in T cells attenuates the development of experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. Growing evidence indicates that myeloid cells are also key players in autoimmune processes. Thus, the present study evaluates the role of the Notch1 receptor in myeloid cells on the progression of myelin oligodendrocyte glycoprotein (MOG)_35‐55‐induced EAE, using mice with a myeloid‐specific deletion of the Notch1 gene (MyeNotch1KO). We found that EAE progression was less severe in the absence of Notch1 in myeloid cells. Thus, histopathological analysis revealed reduced pathology in the spinal cord of MyeNotch1KO mice, with decreased microglia/astrocyte activation, demyelination and infiltration of CD4⁺ T cells. Moreover, these mice showed lower Th1 and Th17 cell infiltration and expression of IFN‐γ and IL‐17 mRNA in the spinal cord. Accordingly, splenocytes from MyeNotch1KO mice reactivated in vitro presented reduced Th1 and Th17 activation, and lower expression of IL‐12, IL‐23, TNF‐α, IL‐6, and CD86. Moreover, reactivated wild‐type splenocytes showed increased Notch1 expression, arguing for a specific involvement of this receptor in autoimmune T cell activation in secondary lymphoid tissues. In summary, our results reveal a key role of the Notch1 receptor in myeloid cells for the initiation and progression of EAE.     

The imbalance of gut microbiota and its correlation with plasma inflammatory cytokines in pemphigus vulgaris patients

Pemphigus vulgaris (PV) is an autoimmune disease characterized by the production of IgG autoantibodies owing to an imbalance in the Th1/Th2 and Th17/Tregs cell pathways. The role of gut microbiota in the development of immune system and autoimmune diseases has been unraveled in the last two decades. However, data pertaining to gut microbiota of PV patients is largely lacking. We aimed to compare the gut microbiota of PV patients and healthy controls and assessed potential correlation with circulating cytokines of Th1/Th2/Th17 cell. Faecal bacterial diversity was analysed in 18 PV patients and 14 age‐ and gender‐matched healthy individuals using hypervariable tag sequencing of the V3‐V4 region of the 16S rRNA gene. Plasma levels of 20 inflammatory cytokines were assessed using the Luminex screening system. As a result, we identified 10 differentially abundant taxa between patients and controls. At the genera level, Lachnospiracea_incertae_sedis and Coprococcus decreased, while Granulicatella, Flavonifractor enriched in PV. Plasma levels of C5a, interleukin (IL)‐2R, IL‐6, IL‐8, IL‐7, IL‐1β, IL17A, IL‐5 and IL‐21 were significantly increased in PV Flavonifractor exhibited a positive correlation with C5a, IL‐6, IL‐8, IL‐7, IL‐1β, IL17A and IL‐21. Lachnospiracea_incertae_sedis and Coprococcus showed a negative correlation with IL‐17A. Our results are consistent with the hypothesis that PV patients have gut microbial dysbiosis which might contribute to the immune disorder and the development of PV.     

Subtypes of type I IFN differentially enhance cytokine expression by suboptimally stimulated CD4+ T cells

Human type I interferons (IFNs) include IFN‐β and 12 subtypes of IFN‐α. During viral infection, infiltrating memory CD4 ⁺ T cells are exposed to IFNs, but their impact on memory T‐cell function is poorly understood. To address this, we pretreated PBMCs with different IFNs for 16 h before stimulation with Staphylococcus aureus enterotoxin B and measured cytokine expression by flow cytometry. IFN‐α8 and ‐α10 most potently enhanced expression of IFN‐γ, IL‐2, and IL‐4. Potency among the subtypes differed most at doses between 10 and 100 U/mL. While enhancement of IL‐2 and IL‐4 correlated with the time of preincubation with type I IFN, IFN‐γ production was enhanced best when IFN‐α was added immediately preceding or simultaneously with T‐cell stimulation. Comparison of T‐cell responses to multiple doses of Staphylococcus aureus enterotoxin B and to peptide libraries from RSV or CMV demonstrated that IFN‐α best enhanced cytokine expression when CD4 ⁺ T cells were suboptimally stimulated. We conclude that type I IFNs enhance Th1 and Th2 function with dose dependency and subtype specificity, and best when T‐cell stimulation is suboptimal. While type I IFNs may beneficially enhance CD4 ⁺ T‐cell memory responses to vaccines or viral pathogens, they may also enhance the function of resident Th2 cells and exacerbate allergic inflammation.     

Multifunctional CD4+ T cells correlate with active Mycobacterium tuberculosis infection

Th1 CD4⁺ T cells and their derived cytokines are crucial for protection against Mycobacterium tuberculosis. Using multiparametric flow cytometry, we have evaluated the distribution of seven distinct functional states (IFN‐γ/IL‐2/TNF‐α triple expressors, IFN‐γ/IL‐2, IFN‐γ/TNF‐α or TNF‐α/IL‐2 double expressors or IFN‐γ, IL‐2 or TNF‐α single expressors) of CD4⁺ T cells in individuals with latent M. tuberculosis infection (LTBI) and active tuberculosis (TB). We found that triple expressors, while detectable in 85–90%TB patients, were only present in 10–15% of LTBI subjects. On the contrary, LTBI subjects had significantly higher (12‐ to 15‐fold) proportions of IL‐2/IFN‐γ double and IFN‐γ single expressors as compared with the other CD4⁺ T‐cell subsets. Proportions of the other double or single CD4⁺ T‐cell expressors did not differ between TB and LTBI subjects. These distinct IFN‐γ, IL‐2 and TNF‐α profiles of M. tuberculosis‐specific CD4⁺ T cells seem to be associated with live bacterial loads, as indicated by the decrease in frequency of multifunctional T cells in TB‐infected patients after completion of anti‐mycobacterial therapy. Our results suggest that phenotypic and functional signatures of CD4⁺ T cells may serve as immunological correlates of protection and curative host responses, and be a useful tool to monitor the efficacy of anti‐mycobacterial therapy.     

NK cells modulate the lung dendritic cell‐mediated Th1/Th17 immunity during intracellular bacterial infection

The impact of the interaction between NK cells and lung dendritic cells (LDCs) on the outcome of respiratory infections is poorly understood. In this study, we investigated the effect and mechanism of NK cells on the function of LDCs during intracellular bacterial lung infection of Chlamydia muridarum in mice. We found that the naive mice receiving LDCs from C. muridarum‐infected NK‐cell‐depleted mice (NK‐LDCs) showed more serious body weight loss, bacterial burden, and pathology upon chlamydial challenge when compared with the recipients of LDCs from infected sham‐treated mice (NK+LDCs). Cytokine analysis of the local tissues of the former compared with the latter exhibited lower levels of Th1 (IFN‐γ) and Th17 (IL‐17), but higher levels of Th2 (IL‐4), cytokines. Consistently, NK‐LDCs were less efficient in directing C. muridarum‐specific Th1 and Th17 responses than NK+LDCs when cocultured with CD4⁺ T cells. In NK cell/LDC coculture experiments, the blockade of NKG2D receptor reduced the production of IL‐12p70, IL‐6, and IL‐23 by LDCs. The neutralization of IFN‐γ in the culture decreased the production of IL‐12p70 by LDCs, whereas the blockade of TNF‐α resulted in diminished IL‐6 production. Our findings demonstrate that NK cells modulate LDC function to elicit Th1/Th17 immunity during intracellular bacterial infection.