IL-17-producing T cells in lung immunity and inflammation

Interleukin 23/interleukin 17 axis activated by Mycobacterium avium complex (MAC) is attenuated in patients with MAC-lung disease

BACKGROUND

Mycobacterium avium complex (MAC)-lung disease (LD) is increasing in patients without human immunodeficiency virus infection. However, data on host vulnerability to MAC-related immune responses, and in particular the interleukin (IL)-23/IL-17 axis, are lacking.

METHODS

We enrolled 50 patients with MAC-LD, 25 age-matched patients with tuberculosis (TB) and 25 controls. We measured levels of plasma cytokines, and studied IL-12/IL-17 responses in macrophage and lymphocyte activation to MAC.

RESULTS

The plasma level of IL-17 in the MAC group was higher than in the TB and control groups. In in-vitro macrophage stimulation, the expression of IL-23 in macrophages was similar in the patients with MAC-LD and controls, although the expression of IL-12 p40 was lower in the patients with MAC-LD. In assays of lymphocyte activation, IL-17 was induced by MAC-primed macrophages, but its level was lower in the patients with MAC-LD and TB than in the controls. The expression of programmed death (PD)-1 receptor was higher in CD4⁺IL17A⁺ lymphocytes in the patients with MAC-LD, and the production of IL-17 was significantly increased by blockade of PD-1 and PD-ligand 1.

CONCLUSIONS

MAC induced a similar expression of IL-23 from macrophages in the patients with MAC-LD compared to the controls, but a lower expression of IL-17 from lymphocytes, which may be through an increased expression of PD-1. The macrophage response of IL-12 p40 was stronger than that of IL-12 p70, and higher in the controls during MAC disease, which may suggest another kind of MAC-related immune evasion.

Novel Approaches to Exploiting Invariant NKT Cells in Cancer Immunotherapy

iNKT cells are a subset of innate-like T cells that utilize an invariant TCR alpha chain complexed with a limited repertoire of TCR beta chains to recognize specific lipid antigens presented by CD1d molecules. Because iNKT cells have an invariant TCR, they can be easily identified and targeted in both humans and mice via standard reagents, making this a population of T cells that has been well characterized. iNKT cells are some of the first cells to respond during an infection. By making different types of cytokines in response to different infection stimuli, iNKT cells help determine what kind of immune response then develops. It has been shown that iNKT cells are some of the first cells to respond during infection with a pathogen and the type of cytokines that iNKT cells make help determine the type of immune response that develops in various situations. Indeed, along with immunity to pathogens, pre-clinical mouse studies have clearly demonstrated that iNKT cells play a critical role in tumor immunosurveillance. They can mediate anti-tumor immunity by direct recognition of tumor cells that express CD1d, and/or via targeting CD1d found on cells within the tumor microenvironment. Multiple groups are now working on manipulating iNKT cells for clinical benefit within the context of cancer and have demonstrated that targeting iNKT cells can have a therapeutic benefit in patients. In this review, we briefly introduce iNKT cells, then discuss preclinical data on roles of iNKT cells and clinical trials that have targeted iNKT cells in cancer patients. We finally discuss how future trials could be modified to further increase the efficacy of iNKT cell therapies, in particular CAR-iNKT and rTCR-iNKT cells.

Taurine chloramine potentiates phagocytic activity of peritoneal macrophages through up-regulation of dectin-1 mediated by heme oxygenase-1-derived carbon monoxide

Resolution of inflammation that occurs after microbial infection or tissue damage is an important physiologic process in maintaining or restoring host homeostasis. Taurine chloramine (TauCl) is formed by a reaction between taurine and hypochlorite in leukocytes, and it is especially abundant in activated neutrophils that encounter an oxidative burst. As neutrophils undergo apoptosis, TauCl is released to the extracellular matrix at the inflamed sites, thereby affecting coexisting macrophages in the inflammatory microenvironment. In this study, we investigated the role of TauCl in phagocytosis by macrophages during resolution of fungal infection-induced inflammation. We found that exogenous TauCl substantially increased the phagocytic efficiency of macrophages through up-regulation of dectin-1, a receptor for fungal β-1,3-glucans, which is present on the membrane of macrophages. Our previous studies demonstrated the induction of heme oxygenase-1 (HO-1) expression in murine peritoneal macrophages treated with TauCl. In the present study, knocking out HO-1 or pharmacologic inhibition of HO-1 with zinc protoporphyrin IX attenuated the TauCl-induced expression of dectin-1 and subsequent phagocytosis. Furthermore, carbon monoxide (CO), a by-product of the HO-1-catalyzed reaction, induced expression of dectin-1 and potentiated phagocytic capability of the macrophages, which appeared to be mediated through up-regulation of peroxisome proliferator-activated receptor γ. Taken together, induction of HO-1 expression and subsequent CO production by TauCl are essential for phagocytosis of fungi by macrophages. Our results suggest that TauCl has important roles in host defense against fungal infection and has therapeutic potential in the management of inflammatory diseases.-Kim, S. H., Zhong, X., Kim, W., Kim, K., Suh, Y.-G., Kim, C., Joe, Y., Chung, H. T., Cha, Y.-N., Surh, Y.-J. Taurine chloramine potentiates phagocytic activity of peritoneal macrophages through up-regulation of dectin-1 mediated by heme oxygenase-1-derived carbon monoxide.

Th17/Treg immunoregulation and implications in treatment of sulfur mustard gas-induced lung diseases

INTRODUCTION

Sulfur mustard (SM) is an extremely toxic gas used in chemical warfare to cause massive lung injury and death. Victims exposed to SM gas acutely present with inhalational lung injury, but among those who survive, some develop obstructive airway diseases referred to as SM-lung syndrome. Pathophysiologically, SM-lung shares many characteristics with smoking-induced chronic obstructive pulmonary disease (COPD), including airway remodeling, goblet cell metaplasia, and obstructive ventilation defect. Some of the hallmarks of COPD pathogenesis, which include dysregulated lung inflammation, neutrophilia, recruitment of interleukin 17A (IL -17A) expressing CD4⁺T cells (Th17), and the paucity of lung regulatory T cells (Tregs), have also been described in SM-lung. Areas covered: A literature search was performed using the MEDLINE, EMBASE, and Web of Science databases inclusive of all literature prior to and including May 2017. Expert commentary: Here we review some of the recent findings that suggest a role for Th17 cell-mediated inflammatory changes associated with pulmonary complications in SM-lung and suggest new therapeutic approaches that could potentially alter disease progression with immune modulating biologics that can restore the lung Th17/Treg balance.

The immunology of asthma: Asthma phenotypes and their implications for personalized treatment

OBJECTIVES

To review current thinking regarding the role of personalized phenotype-driven as opposed to broad guideline-based therapies in asthma and to speculate on the relative contributions of innate (lung) and adaptive (T and B lymphocyte) roles in asthma pathogenesis.

DATA SOURCES

PubMed literature review.

STUDY SELECTIONS

Articles pertaining to asthma pathogenesis, with emphasis on those that included biotherapeutic interventions.

RESULTS

Current methods allow asthma to be divided into phenotypes characterized by the presence or absence of eosinophilic inflammation. Corticosteroids are likely to be only effective in the context of eosinophilic inflammation. Similarly, interventions with biotherapeutic agents currently available or in development have efficacious only when administered to patients with asthma of relevant phenotypes.

CONCLUSION

The availability of biotherapeutic agents that target IgE, interleukin (IL) 5, and, in the near future, IL-13 is an exciting vindication of molecular medicine. However, these biotherapeutic agents are only effective when targeted to patients with specific asthma phenotypes. In Promising biotherapeutic targets are the airway epithelial-derived cytokines IL-25, IL-33, and thymic stromal lymphopoietin. Targeting these lung epithelial-derived mediators, instead of products of the adaptive immune system, may be more likely to improve day-to-day asthma symptoms in contrast to agents that target the adaptive immune system, approaches that primarily act to ameliorate asthma exacerbations.

Pulmonary Interleukin-17-Positive Lymphocytes Increase during Pneumocystis murina Infection but Are Not Required for Clearance of Pneumocystis

Pneumocystis remains an important pathogen of immunosuppressed patients, causing a potentially life-threatening pneumonia. Despite its medical importance, the immune responses required to control infection, including the role of interleukin-17 (IL-17), which is important in controlling other fungal infections, have not been clearly defined. Using flow cytometry and intracellular cytokine staining after stimulation with phorbol myristate acetate and ionomycin, we examined gamma interferon (IFN-γ), IL-4, IL-5, and IL-17 production by lung lymphocytes in immunocompetent C57BL/6 mice over time following infection with Pneumocystismurina We also examined the clearance of Pneumocystis infection in IL-17A-deficient mice. The production of both IFN-γ and IL-17 by pulmonary lymphocytes increased during infection, with maximum production at approximately days 35 to 40, coinciding with peak Pneumocystis levels in the lungs, while minimal changes were seen in IL-4- and IL-5-positive cells. The proportion of cells producing IFN-γ was consistently higher than for cells producing IL-17, with peak levels of ∼25 to 30% of CD3⁺ T cells for the former compared to ∼15% for the latter. Both CD4⁺ T cells and γδ T cells produced IL-17. Administration of anti-IFN-γ antibody led to a decrease in IFN-γ-positive cells, and an increase in IL-5-positive cells, but did not impact clearance of Pneumocystis infection. Despite the increases in IL-17 production during infection, IL-17A-deficient mice cleared Pneumocystis infection with kinetics similar to C57BL/6 mice. Thus, while IL-17 production in the lungs is increased during Pneumocystis infection in immunocompetent mice, IL-17A is not required for control of Pneumocystis infection.

Inflammatory biomarkers for asthma endotyping and consequent personalized therapy

INTRODUCTION

We argue that asthma be considered a syndrome caused by multiple inflammatory pathogenic processes. Bronchial hyperresponsiveness, reversible airflow limitation, and chronic airway inflammation characterize asthma pathophysiology. Personalized Medicine, i.e. a tailored management approach, is appropriate for asthma management and is based on the identification of discrete phenotypes and endotypes. Biomarkers can help define phenotypes and endotypes. Several biomarkers have been described in asthma, but most of them are not commonly available or still need external validation. Areas covered: This review presents useful pragmatic biomarkers available in daily clinical practice for assessing airway inflammation in asthmatic patients. Expert commentary: Eosinophil counts and serum allergen-specific IgE assessments are the most reliable biomarkers. Lung function, mainly concerning FEF_25-75, and nasal cytology may be envisaged as ancillary biomarkers in asthma management. In conclusion, biomarkers have a clinical relevance in asthma in identifying asthma endotypes to direct personalized therapy.

Interluekin-17A (IL17A)

The discovery of the key roles of interleukin-17A (IL-17A) and IL-17A producing cells in inflammation, autoimmune diseases and host defense has led to the experimental targeting of the IL-17A pathway in animal models of diseases as well as in clinical trials in humans. These therapeutic agents include biological products that target IL-17A and IL-23, an upstream regulator of IL-17A production. IL-17A producing T helper cells (Th17 cells) are a distinct lineage from the Th1 and Th2 CD4+ lineages and have been suggested to represent a good drug target in certain inflammatory conditions. Targeting IL-17A has been proven to be a good approach as anti-IL-17A is FDA approved for the treatment of psoriasis in 2015. In host defense, IL-17A has been shown to be mostly beneficial against infection caused by extracellular bacteria and fungi. This review will overview the discovery of IL-17A, the receptors used by this cytokine and its role in mucosal immunity and inflammation.

Identification of IL-17F/frequent exacerbator endotype in asthma

BACKGROUND

Severe asthma might be associated with overexpression of T_h17 cytokines, which induce neutrophil recruitment via neutrophil-mobilizing cytokines in airways.

OBJECTIVE

To study IL-17-related cytokines in nasal/bronchial biopsies from controls and mild asthmatics (MAs) to severe asthmatics (SAs) in relation to exacerbation rate.

METHODS

Inflammatory cells and IL-17A⁺, IL-17F⁺, IL-21⁺, IL-22⁺, and IL-23⁺ cells were examined by immunohistochemistry in cryostat sections of bronchial/nasal biopsies obtained from 33 SAs (21 frequent exacerbators [FEs]), 31 MAs (3 FEs), and 14 controls. IL-17F protein was also measured by ELISA in bronchial/nasal lysates and by immunohistochemistry in bronchial tissue obtained from subjects who died because of fatal asthma. Immunofluorescence/confocal microscopy was used for IL-17F colocalization.

RESULTS

Higher number (P < .05) of neutrophils, IL-17A⁺, IL-17F⁺, and IL-21⁺ cells in bronchial biopsies and higher numbers (P < .01) of IL-17F⁺ and IL-21⁺ cells in nasal biopsies were observed in SAs compared with MAs. Bronchial IL-17F⁺ cells correlated with bronchial neutrophils (r = 0.54), exacerbation rate (r = 0.41), and FEV₁ (r = -0.46). Nasal IL-17F⁺ cells correlated with bronchial IL-17F (r = 0.35), exacerbation rate (r = 0.47), and FEV₁ (r = -0.61). FEs showed increased number of bronchial neutrophils/eosinophils/CD4⁺/CD8⁺ cells and bronchial/nasal IL-17F⁺ cells. Receiver operating characteristic curve analysis evidenced predictive cutoff values of bronchial neutrophils and nasal/bronchial IL-17F for discriminating between asthmatics and controls, between MAs and SAs and between FEs and non-FEs. IL-17F protein increased in bronchial/nasal lysates of SAs and FEs and in bronchial tissue of fatal asthma. IL-17F colocalized in CD4⁺/CD8⁺ cells.

CONCLUSIONS

IL-17-related cytokines expression was amplified in bronchial/nasal mucosa of neutrophilic asthma prone to exacerbation, suggesting a pathogenic role of IL-17F in FEs.

Neutrophil plasticity enables the development of pathological microenvironments: implications for cystic fibrosis airway disease

INTRODUCTION

The pathological course of several chronic inflammatory diseases, including cystic fibrosis, chronic obstructive pulmonary disease, and rheumatoid arthritis, features an aberrant innate immune response dominated by neutrophils. In cystic fibrosis, neutrophil burden and activity of neutrophil elastase in the extracellular fluid have been identified as strong predictors of lung disease severity.

REVIEW

Although neutrophils are generally considered to be rigid, pre-programmed effector leukocytes, recent studies suggest extensive plasticity in how neutrophil functions unfold upon recruitment to peripheral tissues, and how they choose their ultimate fate. Indeed, upon migration to cystic fibrosis airways, neutrophils display dysregulated lifespan, metabolic activation, and altered effector and regulatory functions, consistent with profound adaptation and phenotypic reprogramming. Licensed by signals present in cystic fibrosis airway microenvironment to survive and develop these novel functions, neutrophils orchestrate, in partnership with the epithelium and with the resident microbiota, the evolution of a pathological microenvironment. This microenvironment is defined by altered proteolytic, redox, and metabolic balance and the presence of stable luminal structures in which neutrophils and microbes coexist.

CONCLUSIONS

The elucidation of molecular mechanisms driving neutrophil plasticity in vivo will open new treatment opportunities designed to modulate, rather than block, the crucial adaptive functions fulfilled by neutrophils. This review aims to outline emerging mechanisms of neutrophil plasticity and their participation in the building of pathological microenvironments in the context of cystic fibrosis and other diseases with similar features.

Serum interleukin-17 in Egyptian children with systemic lupus erythematosus: is it related to pulmonary affection?

Objective Pulmonary involvement in paediatric systemic lupus erythematosus (pSLE) is not an uncommon finding; however, subclinical affection occurs more frequently. Many studies have reported that cytokine dysregulation as interleukin-17 (IL-17) over-expression plays a key role in the pathogenesis of systemic lupus erythematosus (SLE). We aim to assess serum levels of IL-17 A and their association with pulmonary involvement in children with SLE. Methods Serum IL-17A levels - determined by solid phase sandwich ELISA - were assessed in forty-two pSLE patients and compared to 45 age-matched healthy controls. All patients were subjected to pulmonary function tests to detect subclinical pulmonary affection. High-resolution CT (HRCT) chest scan was carried out in patients with abnormal pulmonary function tests (PFTs) and those with chronic respiratory symptoms. Results Abnormal PFTs were found in 73% of patients; of them, only 25% had abnormal findings in HRCT chest. Serum levels of IL-17 A were significantly elevated in pSLE patients as compared to healthy controls ( p < 0.001). The serum levels of IL-17 A had a highly significant positive correlation with SLEDAI ( r = 0.811 and p < 0.001) Strong negative correlation was found between serum levels of IL-17A with both FEV1 and FVC ( p < 0.05). Conclusions Serum IL-17A is elevated in pSLE patients, which correlates with disease activity. IL-17 seems to have a possible role in the pathogenesis of subclinical lung affection. Abnormal PFTS may be found in pSLE patients even with normal radiology.

Interleukin-17 Pathophysiology and Therapeutic Intervention in Cystic Fibrosis Lung Infection and Inflammation

Cystic fibrosis (CF) is characterized by an excessive neutrophilic inflammatory response within the airway as a result of defective cystic fibrosis transmembrane receptor (CFTR) expression and function. Interleukin-17A induces airway neutrophilia and mucin production associated with Pseudomonas aeruginosa colonization, which is associated with the pathophysiology of cystic fibrosis. The objectives of this study were to use the preclinical murine model of cystic fibrosis lung infection and inflammation to investigate the role of IL-17 in CF lung pathophysiology and explore therapeutic intervention with a focus on IL-17. Cftr-deficient mice (CF mice) and wild-type mice (WT mice) infected with P. aeruginosa had robust IL-17 production early in the infection associated with a persistent elevated inflammatory response. Intratracheal administration of IL-17 provoked a neutrophilic response in the airways of WT and CF animals which was similar to that observed with P. aeruginosa infection. The neutralization of IL-17 prior to infection significantly improved the outcomes in the CF mice, suggesting that IL-17 may be a therapeutic target. We demonstrate in this report that the pathophysiological contribution of IL-17 may be due to the induction of chemokines from the epithelium which is augmented by a deficiency of Cftr and ongoing inflammation. These studies demonstrate the in vivo contribution of IL-17 in cystic fibrosis lung disease and the therapeutic validity of attenuating IL-17 activity in cystic fibrosis.

Blockade of Interleukin-17 Restrains the Development of Acute Lung Injury

The acute respiratory distress syndrome (ARDS), a clinical complication of severe acute lung injury (ALI) in humans, is a leading cause of morbidity and mortality in critically ill patients. Here, we explored the association between IL-17 and development of ALI using LPS-induced murine model. We found that IL-17 level was elevated in bronchoalveolar lavage (BAL) fluid of ALI mice. Upregulation of IL-17 resulted in increased severity of ALI as evidenced by decreased body weight and survival rate, elevated level of total protein and albumin in BAL fluid, as well as more apparent histopathology changes of lung. Induction of ALI was impaired in IL-17-deficient mice. Management of IL-17 could modulate LPS-induced pulmonary inflammation, as reflected by the total cell and neutrophil counts, proinflammatory cytokines, as well as chemokines in BAL fluid. Of note, blockade of IL-17 effectively inhibited the lung inflammation and alleviated ALI severity. Finally, we confirmed the clinical relevance and found that IL-17 expression was elevated and associated with the disease severity in patients with ARDS. In essence, IL-17 was crucial for development of ALI, suggesting a potential application for IL-17-based therapy in clinical practice.

Endotypes of allergic diseases and asthma: An important step in building blocks for the future of precision medicine

Discoveries from basic science research in the last decade have brought significant progress in knowledge of pathophysiologic processes of allergic diseases, with a compelling impact on understanding of the natural history, risk prediction, treatment selection or mechanism-specific prevention strategies. The view of the pathophysiology of allergic diseases developed from a mechanistic approach, with a focus on symptoms and organ function, to the recognition of a complex network of immunological pathways. Several subtypes of inflammation and complex immune-regulatory networks and the reasons for their failure are now described, that open the way for the development of new diagnostic tools and innovative targeted-treatments. An endotype is a subtype of a disease condition, which is defined by a distinct pathophysiological mechanism, whereas a disease phenotype defines any observable characteristic of a disease without any implication of a mechanism. Another key word linked to disease endotyping is biomarker that is measured and evaluated to examine any biological or pathogenic processes, including response to a therapeutic intervention. These three keywords will be discussed more and more in the future with the upcoming efforts to revolutionize patient care in the direction of precision medicine and precision health. The understanding of disease endotypes based on pathophysiological principles and their validation across clinically meaningful outcomes in asthma, allergic rhinitis, chronic rhinosinusitis, atopic dermatitis and food allergy will be crucial for the success of precision medicine as a new approach to patient management.

Patient stratification and the unmet need in asthma

Asthma is often described as an inflammatory disease of the lungs and in most patients symptomatic treatment with bronchodilators or inhaled corticosteroids is sufficient to control disease. Unfortunately there are a proportion of patients who fail to achieve control despite treatment with the best current treatment. These severe asthma patients have been considered a homogeneous group of patients that represent the unmet therapeutic need in asthma. Many novel therapies have been tested in unselected asthma patients and the effects have often been disappointing, particularly for the highly specific monoclonal antibody-based drugs such as anti-IL-13 and anti-IL-5. More recently, it has become clear that asthma is a syndrome with many different disease drivers. Clinical trials of anti-IL-13 and anti-IL-5 have focused on biomarker-defined patient groups and these trials have driven the clinical progression of these drugs. Work on asthma phenotyping indicates that there is a group of asthma patients where T helper cell type 2 (Th2) cytokines and inflammation predominate and these type 2 high (T2-high) patients can be defined by biomarkers and response to therapies targeting this type of immunity, including anti-IL-5 and anti-IL-13. However, there is still a subset of T2-low patients that do not respond to these new therapies. This T2-low group will represent the new unmet medical need now that the T2-high-targeting therapies have made it to the market. This review will examine the current thinking on patient stratification in asthma and the identification of the T2-high subset. It will also look at the T2-low patients and examine what may be the drivers of disease in these patients.

Decreased IL-17 during treatment of sputum smear-positive pulmonary tuberculosis due to increased regulatory T cells and IL-10

BACKGROUND

Tuberculosis (TB) remains a major public health concern worldwide. Previous studies have demonstrated that IL-17 plays an important role in initial immune response and is involved in both immune-mediated protection and pathology following infection with Mycobacterium tuberculosis (MTB). However, the alterations and regulation of plasma IL-17 level during TB treatment remain unclear. Moreover, the cell type responsible for the production of IL-17 in TB patients requires further study.

METHODS

A total of 20 acid-fast bacilli smear-positive (AFB-positive) pulmonary TB patients and 20 age- and gender-matched healthy volunteers were included in our study. Blood samples were collected in heparinized tubes at the time of diagnosis (AFB-positive group) and 3 weeks after the initiation of therapy, when the sputum smear conversion (AFB-negative group) occurred, followed by symptomatic improvement. IL-17 levels and IL-17-producing cells in PBMCs were detected. Lymphocyte populations in the peripheral blood between the AFB-positive and AFB-negative groups were compared by flow-cytometry. A549 cells, a cell line of alveolar epithelial cells, were applied to determine the extent of the pathological damage mediated by IL-17 following MTB infection. Recombinant human IL-10 was used to investigate the regulation of IL-17 expression after sputum smear conversion in AFB-positive pulmonary TB patients.

RESULTS

Plasma IL-17 level were elevated in patients with sputum AFB-positive pulmonary TB, but substantially decreased after TB treatment and smear conversion. Our data indicate that NKT-like cells might be the main source of IL-17, in addition to conventional T cells in AFB-positive pulmonary TB patients. The secretion of IL-17 may be suppressed by regulatory T (Treg) cells and IL-10 during TB treatment. Moreover, the IL-17 levels were positively correlated to both the C-reactive protein and erythrocyte sedimentation rate. Therefore, IL-17 was capable of alveolar epithelial cell damage following MTB infection.

CONCLUSION

The increase in the frequency of Treg cells and IL-10 levels was associated with a decrease in IL-17 in patients receiving TB treatment. Thus, IL-10 and Tregs may function to inhibit immune-mediated pathology in TB patients.

S-adenosylmethionine reduces airway inflammation and fibrosis in a murine model of chronic severe asthma via suppression of oxidative stress

Increased oxidative stress has an important role in asthmatic airway inflammation and remodeling. A potent methyl donor, S-adenosylmethionine (SAMe), is known to protect against tissue injury and fibrosis through modulation of oxidative stress. The aim of this study was to evaluate the effect of SAMe on airway inflammation and remodeling in a murine model of chronic asthma. A mouse model was generated by repeated intranasal challenge with ovalbumin and Aspergillus fungal protease twice a week for 8 weeks. SAMe was orally administered every 24 h for 8 weeks. We performed bronchoalveolar lavage (BAL) fluid analysis and histopathological examination. The levels of various cytokines and 4-hydroxy-2-nonenal (HNE) were measured in the lung tissue. Cultured macrophages and fibroblasts were employed to evaluate the underlying anti-inflammatory and antifibrotic mechanisms of SAMe. The magnitude of airway inflammation and fibrosis, as well as the total BAL cell counts, were significantly suppressed in the SAMe-treated groups. A reduction in T helper type 2 pro-inflammatory cytokines and HNE levels was observed in mouse lung tissue after SAMe administration. Macrophages cultured with SAMe also showed reduced cellular oxidative stress and pro-inflammatory cytokine production. Moreover, SAMe treatment attenuated transforming growth factor-β (TGF-β)-induced fibronectin expression in cultured fibroblasts. SAMe had a suppressive effect on airway inflammation and fibrosis in a mouse model of chronic asthma, at least partially through the attenuation of oxidative stress and TGF-β-induced fibronectin expression. The results of this study suggest a potential role for SAMe as a novel therapeutic agent in chronic asthma.

Innate and Adaptive Immunity in Cystic Fibrosis

Cystic fibrosis (CF) lung disease is characterized by persistent and unresolved inflammation, with elevated proinflammatory and decreased anti-inflammatory cytokines, and greater numbers of immune cells. Hyperinflammation is recognized as a leading cause of lung tissue destruction in CF. Hyper-inflammation is not solely observed in the lungs of CF patients, since it may contribute to destruction of exocrine pancreas and, likely, to defects in gastrointestinal tract tissue integrity. Paradoxically, despite the robust inflammatory response, and elevated number of immune cells (such as neutrophils and macrophages), CF lungs fail to clear bacteria and are more susceptible to infections. Here, we have summarized the current understanding of immune dysregulation in CF, which may drive hyperinflammation and impaired host defense.

Th17 cells reflect colon submucosal pathologic changes in active eosinophilic granulomatosis with polyangiitis

BACKGROUND

Chronic eosinophilic pneumonia (CEP) or eosinophilic gastroenteritis (EG), or both, with asthma precede the onset of eosinophilic granulomatosis with polyangiitis (EGPA) in half of all EGPA patients. It is not known what determines whether patients with CEP or with EG following asthma will develop EGPA.

METHODS

We studied 17 EGPA patients and 12 patients with CEP but without EGPA. We assayed serum ICAM-1, VCAM-1, and VEGF, and the percentage of peripheral blood CD4(+) T cells producing IL-17 (Th17 cells), at both onset and remission. We also examined the numbers of submucosal eosinophils and the basement membrane-to-crypt and crypt-to-crypt distance to evaluate edema in the colon submucosa at onset and remission in EGPA and at onset in CEP.

RESULTS

Nine of 12 (75.0%) CEP patients had symptoms or endoscopic findings. Colonic submucosal eosinophil counts and edema in EGPA at onset were greater than at remission or in CEP at onset. Th17 cells (%) and serum ICAM-1 levels at onset were greater in EGPA than in CEP. In EGPA, peripheral blood Th17 cells (%) were significantly correlated with serum ICAM-1 level, colonic submucosal eosinophil count, and degree of edematous change; inversely correlated with serum VEGF level; but not correlated with VCAM-1 level.

CONCLUSIONS

Eosinophilia and colonic submucosal edematous change were greater in EGPA than in CEP. The mechanism of vasculitis in EGPA appears related to increases in serum Th17 cell numbers and ICAM-1 levels and decreases in VEGF levels.

Expression of IL-17A concentration and effector functions of peripheral blood neutrophils in food allergy hypersensitivity patients

Lymphocytes Th17 and other types of immune system cells produce IL17. By induction of cytokines and chemokines, the IL17 cytokine is involved in mechanisms of allergic reaction with participation of neutrophil granulocytes. It affects activation, recruitment, and migration of neutrophils to the tissues, regulating inflammatory reaction intensity. Excited neutrophils secrete inter alia elastase and reactive oxygen species (ROS)--significant mediators of inflammation process responsible for tissues damage.The aim of the study was to evaluate the concentrations of serum interleukin 17A, serum neutrophil elastase, and ROS production by neutrophils in patients with food allergy.The study included 30 patients with food allergy diagnosed based on interview, clinical symptoms, positive SPT, placebo controlled double-blind oral provocation trial, and the presence of asIgE in blood serum against selected food allergens using fluoro-immuno-enzymatic method FEIA UNICap 100. The control group consisted of 10 healthy volunteers. The concentrations of IL17A were determined in all patients using ELISA method with eBioscience kits, and elastase using BenderMed Systems kits. Chemiluminescence of non-stimulated neutrophils was evaluated using luminol-dependent kinetic method for 40 min on Luminoskan (Labsystems luminometer).The results of serum IL-17A concentrations and the values of chemiluminescence obtained by non-activated neutrophils, as well as elastase concentrations, were higher in patients with food allergic hypersensitivity compared to healthy volunteers.This study demonstrates a significance of IL-17A and activated neutrophil granulocytes in the course of diseases with food allergic hypersensitivity.

Cigarette smoke affects IL-17A, IL-17F and IL-17 receptor expression in the lung tissue: Ex vivo and in vitro studies

Cigarette smoke is a risk factor for Chronic Obstructive Pulmonary Disease (COPD). Th-17 cytokines are involved in the pathogenesis of COPD. We aimed to evaluate the role of cigarette smoke on the expression of IL-17A, IL-17F and IL-17R in airways of COPD patients. Epithelial and subepithelial immunoreactivity for IL-17A, IL-17F and IL-17R was assessed in surgical specimens from COPD patients (n=15) and from healthy subjects (HC) (n=10) by immunohistochemistry. In vitro, human epithelial cell line 16HBE and A549 as well as PBMC from normal donors were stimulated with cigarette smoke extract (CSE) (0%, 2.5%, 5%, 10%) to evaluate the IL-17A, IL-17F and IL-17R expression by flow cytometry. Furthermore, rhIL-17A and CSE stimulation was evaluated on proliferation and apoptosis in 16HBE and in A549. In central and distal airways immunoreactivity for IL-17A, IL-17F and IL-17R significantly increased in the epithelium and IL-17A in the subepithelium from COPD than in HC. In distal airway, immunoreactivity for IL-17F increased in the subepithelium of COPD than in HC. IL-17A immunoreactivity positively correlate with IL-17R and total pack years in the epithelium from central and distal airways of COPD patients. In vitro, CSE stimulation significantly increased IL-17F and IL-17R in 16HBE (2.5%) and A549 (5%) while IL-17A and IL-17F in PBMC (10%). IL-17A and CSE stimulation, rather than CSE or rhIL-17A alone, significantly increased proliferation in 16HBE and apoptosis in A549. Cigarette smoke increases Th17 immunity in lung tissue of COPD patients, promoting the mechanism of proliferation and apoptosis in airway epithelial cells.

The association between the Th-17 immune response and pulmonary complications in a trauma ICU population

BACKGROUND

The overall immunopathology of the T-helper cell (Th)-17 immune response has been implicated in various inflammatory diseases including pulmonary inflammation; however its potential role in acute respiratory distress syndrome (ARDS) is not defined. This study aimed to evaluate the Th-17 response in bronchoalveolar lavage fluid (BALF) and blood and from trauma patients with pulmonary complications.

METHODS

A total of 21 severely injured intensive care unit (ICU) subjects, who were mechanically ventilated and undergoing bronchoscopy, were enrolled. BALF and blood were collected and analyzed for Th-1 (interferon [IFN]γ), Th-2 (interleukin [IL]-4, -10), Th-17 (IL-17A, -17F, -22, 23) and pro-inflammatory (IL-1β, IL-6, tumor necrosis factor [TNF]α) cytokine levels.

RESULTS

Significant levels of the Th-17 cytokines IL-17A, -17F and -21 and IL-6 (which can be classified as a Th-17 cytokine) were observed in the BALF of all subjects. There were no significant differences in Th-17 cytokines between those subjects with ARDS and those without, with the exception of plasma and BALF IL-6, which was markedly greater in ARDS subjects, as compared with controls and non-ARDS subjects.

CONCLUSIONS

Trauma patients with pulmonary complications exhibited a significant Th-17 response in the lung and blood, suggesting that this pro-inflammatory milieu may be a contributing factor to such complications.

IL-17 polymorphisms and asthma risk: a meta-analysis of 11 single nucleotide polymorphisms

OBJECTIVE

There has been significant interest in the association between asthma and the polymorphisms of IL-17A and IL-17F for a period of time. This work aims to present a clearer relationship between asthma and the polymorphisms of IL-17A and IL-17F.

METHOD

Searches were performed in Medline, EMBASE, and the Chinese National Knowledge Infrastructure (CNKI) databases. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the relationship between polymorphisms of IL-17A and IL-17F and asthma.

RESULTS

Nine studies comprising 3650 asthmatics and 3370 controls were included in this meta-analysis for all single nucleotide polymorphisms (SNPs) (2-6 per SNP). Our study examined the polymorphisms of IL-17F rs1889570 (C/T) (CC versus TT: OR = 0.55, 95%CI = 0.41-0.75; CT versus TT: OR = 0.54, 95%CI = 0.40-0.72; CC/CT versus TT: OR = 0.55, 95%CI = 0.42-0.72; CC versus CT/TT, OR = 1.83, 95%CI = 1.39-2.41), IL-17A rs4711998(A/G) (AA/AG versus GG: OR = 0.67, 95%CI = 0.46-0.98), and IL-17A rs3819024(A/G) (AA versus GG: OR = 1.77, 95%CI = 1.39-2.25) and found they were significantly related to the risk of asthma.

CONCLUSION

Our systematic review showed that IL-17F rs1889570(C/T), IL-17A rs4711998(A/G) and IL-17A rs3819024(A/G) may be potential risk factors for asthma susceptibility.

IL-17 and neutrophils: unexpected players in the type 2 immune response

The study of immunity to helminth infection has been central to understanding the function of type 2 cytokines and their targets. Although type 2 cytokines are considered anti-inflammatory and promote tissue repair, they also contribute to allergy and fibrosis. Here, we utilise data from helminth infection models, to illustrate that IL-17 and neutrophils, typically associated with pro-inflammatory responses, are intimately linked with type 2 immunity. Neutrophils work with IL-4Rα-activated macrophages to control incoming larvae but this comes at a cost of enhanced tissue damage. Chitinase like proteins (CLPs) bridge these diverse outcomes, inducing both protective IL-17 and reparative Th2 responses. Dysregulation of CLPs, IL-17 and neutrophils likely contribute to disease severity and pathology associated with type 2 immunity.

IL-17 in severe asthma. Where do we stand?

Asthma is a major chronic disease ranging from mild to severe refractory disease and is classified into various clinical phenotypes. Severe asthma is difficult to treat and frequently requires high doses of systemic steroids. In some cases, severe asthma even responds poorly to steroids. Several studies have suggested a central role of IL-17 (also called IL-17A) in severe asthma. Indeed, high levels of IL-17 are found in induced sputum and bronchial biopsies obtained from patients with severe asthma. The recent identification of a steroid-insensitive pathogenic Th17 pathway is therefore of major interest. In addition, IL-17A has been described in multiple aspects of asthma pathogenesis, including structural alterations of epithelial cells and smooth muscle contraction. In this perspective article, we frame the topic of IL-17A effects in severe asthma by reviewing updated information from human studies. We summarize and discuss the implications of IL-17 in the induction of neutrophilic airway inflammation, steroid insensitivity, the epithelial cell profile, and airway remodeling.

Nasal IL-17F is related to bronchial IL-17F/neutrophilia and exacerbations in stable atopic severe asthma

Severe asthma (SA) is associated with neutrophil recruitment and T helper (TH )17 chemokine overexpression in bronchial biopsies. We aimed to evaluate IL-17A and IL-17F expression in nasal/bronchial lamina propria of atopic mild-to-severe asthmatics and controls in relation to neutrophilia and asthma exacerbations. Cryostat sections of nasal/bronchial biopsies obtained from 14 SA and 14 mild asthma (MA) stable atopic patients with rhinitis, and seven healthy controls were analyzed by immunohistochemistry for neutrophils, IL-17A and IL-17F expression. Atopic SA showed an increase in asthma exacerbations number, IL-17F and IL-17A expression in nasal/bronchial lamina propria compared to MA and controls, and a higher expression of bronchial neutrophils in SA compared to MA and controls. In all asthmatics, significant relationships were found between bronchial IL-17F and neutrophils/FEV1 , nasal IL-17F and bronchial neutrophil/IL-17 markers and between the latter and exacerbations, suggesting that nasal IL-17F might be informative on bronchial IL17-driven neutrophilia in atopic SA.

Therapeutic effects of resveratrol in a mouse model of HDM-induced allergic asthma

Asthma is an inflammatory disease of the lungs characterized by airway remolding. In this study, we examined whether resveratrol exerts protective effects on allergic asthma in a murine model. To investigate the effects of resveratrol on allergic airway inflammation in house dust mite (HDM)-induced mouse asthma and explore its mechanism, a chronic asthma mouse model was established by intranasally administering extracts of HDM (25μg of protein in 10μl of saline) for 5days/week for up to 7 consecutive weeks. Resveratrol (50mg/kg body weight), dexamethasone (1mg/kg body weight) or a vehicle was administered orally 1h before antigen challenges for up to 2weeks. Compared with the HDM-induced mice, the level of TNF-α of the BALF in the resveratrol+HDM-treated mice had obviously decreased. Histological examination of the lung tissue revealed that the resveratrol treatments attenuated the fibrotic response and airway inflammation. In addition, resveratrol inhibited the expression of the Syk protein and degranulation in mast cells. The presented findings collectively suggest that resveratrol has a therapeutic effect on mouse allergic asthma, and its mechanism of action might be related to reducing the production of the Syk protein.

CD3bright signals on γδ T cells identify IL-17A-producing Vγ6Vδ1+ T cells

Interleukin-17A (IL-17A) is a pro-inflammatory cytokine that has an important role at mucosal sites in a wide range of immune responses including infection, allergy and auto-immunity. γδ T cells are recognized as IL-17 producers, but based on the level of CD3 expression, we now define the remarkable ability of a CD3(bright) γδ T-cell subset with an effector memory phenotype to rapidly produce IL-17A, but not interferon-γ. CD3(bright) γδ T cells uniformly express the canonical germline encoded Vγ6/Vδ1(+) T-cell receptor. They are widely distributed with a preferential representation in the lungs and skin are negatively impacted in the absence of retinoic acid receptor-related orphan receptor gammat expression or endogenous flora. This population responded rapidly to various stimuli in a mechanism involving IL-23 and NOD-like receptor family, pyrin domain containing 3 (NLRP3)-inflammasome-dependent IL-1β. Finally, we demonstrated that IL-17-producing CD3(bright) γδ T cells responded promptly and strongly to pneumococcal infection and during skin inflammation. Here, we propose a new way to specifically analyze IL-17-producing Vγ6/Vδ1(+) T cells based on the level of CD3 signals. Using this gating strategy, our data reinforce the crucial role of this γδ T-cell subset in respiratory and skin disorders.

B lymphocytes regulate airway granulocytic inflammation and cytokine production in a murine model of fungal allergic asthma

Sensitization to fungi often leads to a severe form of asthma that is particularly difficult to manage clinically, resulting in increased morbidity and hospitalizations in these patients. Although B lymphocytes might exacerbate asthma symptoms through the production of IgE, these cells might also be important in the protective response against inhaled fungi. Through cytokine release and T-cell interactions, these lymphocytes might also influence the development and maintenance of airway wall fibrosis. J(H)(-/-) mice lack the JH gene for the heavy chain component of antibodies, which is critical for B-cell function and survival. These animals have facilitated the elucidation of the role of B lymphocytes in a number of immune responses; however, J(H)(-/-) mice have not been used to study fungal allergy. In this study, we examined the role of B lymphocytes using an Aspergillus fumigatus murine fungal aeroallergen model that mimics human airway disease that is triggered by environmental fungal exposure. We compared disease progression in sensitized wild-type BALB/c and J(H)(-/-) mice that were exposed to repeated fungal exposure and found no differences in airway hyperresponsiveness, overall pulmonary inflammation or collagen deposition around the large airways. However, the levels of the Th2-type cytokines IL-4 and IL-13 were significantly attenuated in the airways of J(H)(-/-) mice relative to the BALB/c controls. By contrast, levels of the inflammatory cytokines IL-17A and IL-6 were significantly elevated in the J(H)(-/-) animals, and there was significantly more robust airway eosinophilia and neutrophilia than in control animals. Taken together, these findings demonstrate that B lymphocytes help to regulate granulocytic responses to fungal exposure in the pulmonary compartment.

Interleukin-22 exacerbates airway inflammation induced by short-term exposure to cigarette smoke in mice

AIM

Interleukin-22 (IL-22) exhibits both proinflammatory and anti-inflammatory properties in various biological processes. In this study we explored the effects of exogenous recombinant IL-22 (rIL-22) on cigarette smoke (CS)-induced airway inflammation in mice.

METHODS

Male C57BL/6 mice were divided into groups: (1) CS group exposed to tobacco smoke for 3 consecutive days, (2) rIL-22 group received rIL-22 (100 mg/kg, ip), and (3) CS plus rIL-22 group, received rIL-22 (100 mg/kg, ip) before the CS exposure. The airway resistance (Rn), lung morphology, inflammatory cells in the airways, and inflammatory cytokines and CXCR3 ligands in both bronchoalveolar lavage (BAL) fluids and lung tissues were analyzed.

RESULTS

CS alone significantly elevated IL-22 level in the BAL fluid. Both CS and rIL-22 significantly augmented airway resistance, an influx of inflammatory cells into the airways and lung parenchyma, and significantly elevated levels of pro-inflammatory cytokines (TGFβ1 and IL-17A) and CXCR3 chemokines (particularly CXCL10) at the mRNA and/or protein levels. Furthermore, the effects of rIL-22 on airway resistance and inflammation were synergistic with those of CS, as demonstrated by a further increased Rn value, infiltration of greater numbers of inflammatory cells into the lung, higher levels of inflammatory cytokines and chemokines, and more severe pathological changes in CS plus rIL-22 group as compared to those in CS group.

CONCLUSION

Exogenous rIL-22 exacerbates the airway inflammatory responses to CS exposure in part by inducing expression of several proinflammatory cytokines and CXCR3 ligands.

Th17 can regulate silica-induced lung inflammation through an IL-1β-dependent mechanism

Silicosis is an occupational lung disease caused by the inhalation of silica dust and characterized by lung inflammation and fibrosis. Interleukin (IL)-1β is induced by silica and functions as the key pro-inflammatory cytokine in this process. The Th17 response, which is induced by IL-1β, has been reported very important in chronic human lung inflammatory diseases. To elucidate the underlying mechanisms of IL-1β and IL-17 in silicosis, we used anakinra and an anti-IL-17 monoclonal antibody (mAb) to block the receptor of IL-1β (IL-RI) and IL-17, respectively, in a mouse model of silicosis. We observed increased IL-1β expression and an enhanced Th17 response after silica instillation. Treatment with an IL-1 type I receptor (IL-1RI) antagonist anakinra substantially decreased silica-induced lung inflammation and the Th17 response. Lung inflammation and the accumulation of inflammatory cells were attenuated in the IL-17-neutralized silicosis group. IL-17 may promote lung inflammation by modulating the differentiation of Th1 and regulatory T cells (Tregs) and by regulating the production of IL-22 and IL-1β during the lung inflammation of silicosis. Silica may induce IL-1β production from alveolar macrophages and promote inflammation by initiating a Th17 response via an IL-1β/IL-1RI-dependent mechanism. The Th17 response could induce lung inflammation during the pathogenesis of silicosis by regulating the homoeostasis of the Th immune responses and affecting the production of IL-22 and IL-1β. This study describes a potentially important inflammatory mechanism of silicosis that may bring about novel therapies for this inflammatory and fibrotic disease.

Could T cells be involved in lung deterioration and hyperglycemia in cystic fibrosis?

Cystic fibrosis-related diabetes (CFRD) is the most frequent complication of cystic fibrosis (CF) and associated with increased mortality. Why patients have an accelerated loss of lung function before the diagnosis of CFRD remains poorly understood. We reported that patients with or without CFRD had increased glucose excursions when compared to healthy peers. Studies have demonstrated that patients with CF have increased glucose fluctuations and hyperglycemia and that this may affect the clinical course of CF and lead to lymphocyte dysfunction. T-helper 17 (Th17) lymphocytes produce and secrete the pro-inflammatory cytokine IL-17. The Th17 pathway is involved in CF lung inflammation, β-cell destruction in type 1 diabetes (T1D) and Th17 cells of patients with type 2 diabetes have increased production of IL-17 when compared to healthy peers. Also, regulatory T-cells (Tregs) have been shown to be dysfunctional and produce IL-17 in T1D. Furthermore, vitamin D can affect inflammation in CF, diabetes and the differentiation of lymphocytes. In this review, we discuss the potential roles of hyperglycemia on Th17 cells, Tregs and IL-17 as a potential cause for accelerated lung function decline before CFRD and how this could be modulated by vitamin D or by directly intervening in the IL-17A pathway.

Key mediators in the immunopathogenesis of allergic asthma

Asthma is described as a chronic inflammatory disorder of the conducting airways. It is characterized by reversible airway obstruction, eosinophil and Th2 infiltration, airway hyper-responsiveness and airway remodeling. Our findings to date have largely been dependent on work done using animal models, which have been instrumental in broadening our understanding of the mechanism of the disease. However, using animals to model a uniquely human disease is not without its drawbacks. This review aims to examine some of the key mediators and cells of allergic asthma learned from animal models and shed some light on emerging mediators in the pathogenesis allergic airway inflammation in acute and chronic asthma.

The role of the γ δ T cell in allergic diseases

The predominant distribution of γδ T cells in the mucosal and epithelial tissues makes these unconventional lymphocytes the “guards” to contact external environment (like allergens) and to contribute to immune surveillance, as well as “vanguards” to participate in initiating mucosal inflammation. Therefore, γδ T cells have been considered to bridge the innate and adaptive immunity. The role these cells play in allergy seems to be complicated and meaningful, so it makes sense to review the characteristics and role of γδ T cells in allergic diseases.

IL-17A mediates a selective gene expression profile in asthmatic human airway smooth muscle cells

Airway smooth muscle (ASM) cells are thought to contribute to the pathogenesis of allergic asthma by orchestrating and perpetuating airway inflammation and remodeling responses. In this study, we evaluated the IL-17RA signal transduction and gene expression profile in ASM cells from subjects with mild asthma and healthy individuals. Human primary ASM cells were treated with IL-17A and probed by the Affymetrix GeneChip array, and gene targets were validated by real-time quantitative RT-PCR. Genomic analysis underlined the proinflammatory nature of IL-17A, as multiple NF-κB regulatory factors and chemokines were induced in ASM cells. Transcriptional regulators consisting of primary response genes were overrepresented and displayed dynamic expression profiles. IL-17A poorly enhanced IL-1β or IL-22 gene responses in ASM cells from both subjects with mild asthma and healthy donors. Interestingly, protein modifications to the NF-κB regulatory network were not observed after IL-17A stimulation, although oscillations in IκBε expression were detected. ASM cells from subjects with mild asthma up-regulated more genes with greater overall variability in response to IL-17A than from healthy donors. Finally, in response to IL-17A, ASM cells displayed rapid activation of the extracellular signal-regulated kinase/ribosomal S6 kinase signaling pathway and increased nuclear levels of phosphorylated extracellular signal-regulated kinase. Taken together, our results suggest that IL-17A mediated modest gene expression response, which, in cooperation with the NF-κB signaling network, may regulate the gene expression profile in ASM cells.

Timed action of IL-27 protects from immunopathology while preserving defense in influenza

Infection with influenza virus can result in massive pulmonary infiltration and potentially fatal immunopathology. Understanding the endogenous mechanisms that control immunopathology could provide a key to novel adjunct therapies for this disease. Here we show that the cytokine IL-27 plays a crucial role in protection from exaggerated inflammation during influenza virus infection. Using Il-27ra^−/− mice, IL-27 was found to limit immunopathology, neutrophil accumulation, and dampened T_H1 or T_H17 responses via IL-10–dependent and -independent pathways. Accordingly, the absence of IL-27 signals resulted in a more severe disease course and in diminished survival without impacting viral loads. Consistent with the delayed expression of endogenous Il-27p28 during influenza, systemic treatment with recombinant IL-27 starting at the peak of virus load resulted in a major amelioration of lung pathology, strongly reduced leukocyte infiltration and improved survival without affecting viral clearance. In contrast, early application of IL-27 impaired virus clearance and worsened disease. These findings demonstrate the importance of IL-27 for the physiological control of immunopathology and the potential value of well-timed IL-27 application to treat life-threatening inflammation during lung infection.

Annual epidemics of influenza result in 3 to 5 million cases of severe illness and approximately 300,000 deaths around the world. Although most patients infected with normal circulating influenza A viruses recover from the illness, complications arise during infections with highly pathogenic strains of the virus, resulting in increased mortality associated with severe immunopathology and acute respiratory distress. Previous studies suggested a major contribution of the vigorous immune response to lung damage. How the immune system constrains the negative impact of inflammation might therefore be of significant importance for future therapies. Our study in a mouse model of influenza shows that the cytokine IL-27 plays a crucial role in survival by protecting against lung damage. Its actions include regulation of innate (neutrophil influx) and adaptive (inflammatory cytokine production of T cells) arms of immunity during the acute respiratory infection. The data also suggest a therapeutic potential of IL-27, as mice treated with recombinant cytokine at later stages of infection exhibited decreased immunopathology and showed improved survival. The findings uncover an important role of IL-27 in limiting the collateral damages of anti-viral immunity and provide initial evidence that these mechanisms might be exploited for the management of severe immunopathology after infection.

Local expression of interleukin-17a is correlated with nasal eosinophilia and clinical severity in allergic rhinitis

Interleukin (IL)-17A is a major cytokine produced by Th17 cells, which are associated with chronic inflammations. The local expression of IL-17A in allergic rhinitis (AR) remains to be characterized. We sought to determine the role of IL-17A expression in human inferior turbinate mucosa in the pathophysiology of AR. Inferior turbinate mucosa was sampled from medical treatment–resistant, surgery-required patients with perennial AR (PAR, n = 21), nonallergic rhinitis with eosinophilia syndrome (NARES, n = 7), and nonallergic hypertrophic rhinitis (HR, n = 13). IL-17A expression was determined with immunohistochemical staining. The mean number of IL-17A⁺ cells and eosinophils per field were counted. Total serum immunoglobulin E (IgE) levels, blood eosinophil count, and forced expiratory volume in 1 second (FEV₁)/forced vital capacity (FVC) ratio were also examined in each patient. IL-17A was primarily expressed in infiltrating inflammatory cells. The number of IL-17A⁺ cells in nasal mucosa was significantly higher in the PAR group compared with HR (p = 0.002) and NARES (p = 0.021) groups. There was a significant and positive correlation between the number of IL-17A⁺ cells and total nasal symptom score (rho = 0.403; p = 0.011), especially sneezing score (rho = 0.471; p = 0.003). The number of IL-17A⁺ cells was significantly and positively correlated with the degree of eosinophil infiltration (rho = 0.623; p < 0.001), but not with total serum IgE levels (rho = 0.284; p = 0.098), blood eosinophil counts (rho = 0.302; p = 0.056), or FEV₁/FVC ratio (rho = 0.092; p = 0.569). The present study provides evidence that IL-17A expression in the nasal mucosa is associated with the pathophysiology of AR, including disease severity and nasal eosinophilia.

Pulmonary immune responses to Aspergillus fumigatus in an immunocompetent mouse model of repeated exposures

Aspergillus fumigatus is a filamentous fungus that produces abundant pigmented conidia. Several fungal components have been identified as virulence factors, including melanin; however, the impact of these factors in a repeated exposure model resembling natural environmental exposures remains unknown. This study examined the role of fungal melanin in the stimulation of pulmonary immune responses using immunocompetent BALB/c mice in a multiple exposure model. It compared conidia from wild-type A. fumigatus to two melanin mutants of the same strain, Δarp2 (tan) or Δalb1 (white). Mass spectrometry-based analysis of conidial extracts demonstrated that there was little difference in the protein fingerprint profiles between the three strains. Field emission scanning electron microscopy demonstrated that the immunologically inert Rodlet A layer remained intact in melanin-deficient conidia. Thus, the primary difference between the strains was the extent of melanization. Histopathology indicated that each A. fumigatus strain induced lung inflammation, regardless of the extent of melanization. In mice exposed to Δalb1 conidia, an increase in airway eosinophils and a decrease in neutrophils and CD8(+) IL-17(+) (Tc17) cells were observed. Additionally, it was shown that melanin mutant conidia were more rapidly cleared from the lungs than wild-type conidia. These data suggest that the presence of fungal melanin may modulate the pulmonary immune response in a mouse model of repeated exposures to A. fumigatus conidia.

Attenuated Bordetella pertussis vaccine protects against respiratory syncytial virus disease via an IL-17-dependent mechanism

RATIONALE

We attenuated virulent Bordetella pertussis by genetically eliminating or detoxifying three major toxins. This strain, named BPZE1, is being developed as a possible live nasal vaccine for the prevention of whooping cough. It is immunogenic and safe when given intranasally in adult volunteers.

OBJECTIVES

Before testing in human infants, we wished to examine the potential effect of BPZE1 on a common pediatric infection (respiratory syncytial virus [RSV]) in a preclinical model.

METHODS

BPZE1 was administered before or after RSV administration in adult or neonatal mice. Pathogen replication, inflammation, immune cell recruitment, and cytokine responses were measured.

MEASUREMENTS AND MAIN RESULTS

BPZE1 alone did not cause overt disease, but induced efflux of neutrophils into the airway lumen and production of IL-10 and IL-17 by mucosal CD4(+) T cells. Given intranasally before RSV infection, BPZE1 markedly attenuated RSV, preventing weight loss, reducing viral load, and attenuating lung cell recruitment. Given neonatally, BPZE1 also protected against RSV-induced weight loss even through to adulthood. Furthermore, it markedly increased IL-17 production by CD4(+) T cells and natural killer cells and recruited regulatory cells and neutrophils after virus challenge. Administration of anti-IL-17 antibodies ablated the protective effect of BPZE1 on RSV disease.

CONCLUSIONS

Rather than enhancing RSV disease, BPZE1 protected against viral infection, modified viral responses, and enhanced natural mucosal resistance. Prevention of RSV infection by BPZE1 seems in part to be caused by induction of IL-17. Clinical trial registered with www.clinicaltrials.gov (NCT 01188512).

Enhanced response to pulmonary Streptococcus pneumoniae infection is associated with primary ciliary dyskinesia in mice lacking Pcdp1 and Spef2

Background

Lower airway abnormalities are common in patients with primary ciliary dyskinesia (PCD), a pediatric syndrome that results from structural or functional defects in motile cilia. Patients can suffer from recurrent bacterial infection in the lung, bronchiectasis, and respiratory distress in addition to chronic sinusitis, otitis media, infertility, and laterality defects. However, surprisingly little is known about the pulmonary phenotype of mouse models of this disorder.

Results

The pulmonary phenotype of two mouse models of PCD, nm1054 and bgh, which lack Pcdp1 and Spef2, respectively, was investigated by histological and immunohistochemical analysis. In addition, both models were challenged with Streptococcus pneumoniae, a common respiratory pathogen found in the lungs of PCD patients. Histopathological analyses reveal no detectable cellular, developmental, or inflammatory abnormalities in the lower airway of either PCD model. However, exposure to S. pneumoniae results in a markedly enhanced inflammatory response in both models. Based on analysis of inflammatory cells in bronchoalveolar lavage fluid and flow cytometric analysis of cytokines in the lung, the bgh model shows a particularly dramatic lymphocytic response by 3 days post-infection compared to the nm1054 model or wild type animals.

Conclusions

Defects in ciliary motility result in a severe response to pulmonary infection. The PCD models nm1054 and bgh are distinct and clinically relevant models for future studies investigating the role of mucociliary clearance in host defense.

Pathogenic memory type Th2 cells in allergic inflammation

Immunological memory is a hallmark of adaptive immunity. Memory CD4 T helper (Th) cells are central to acquired immunity, and vaccines for infectious diseases are developed based on this concept. However, memory Th cells also play a critical role in the pathogenesis of various chronic inflammatory diseases, including asthma. We refer to these populations as 'pathogenic memory Th cells.' Here, we review recent developments highlighting the functions and characteristics of several pathogenic memory type Th2 cell subsets in allergic inflammation. Also discussed are the similarities and differences between pathogenic memory Th2 cells and recently identified type 2 innate lymphoid cells (ILC2), focusing on cytokine production and phenotypic profiles.

Interleukin-17A enhances host defense against cryptococcal lung infection through effects mediated by leukocyte recruitment, activation, and gamma interferon production

Infection of C57BL/6 mice with the moderately virulent Cryptococcus neoformans strain 52D models the complex adaptive immune response observed in HIV-negative patients with persistent fungal lung infections. In this model, Th1 and Th2 responses evolve over time, yet the contribution of interleukin-17A (IL-17A) to antifungal host defense is unknown. In this study, we show that fungal lung infection promoted an increase in Th17 T cells that persisted to 8 weeks postinfection. Our comparison of fungal lung infection in wild-type mice and IL-17A-deficient mice (IL-17A(-/-) mice; C57BL/6 genetic background) demonstrated that late fungal clearance was impaired in the absence of IL-17A. This finding was associated with reduced intracellular containment of the organism within lung macrophages and deficits in the accumulation of total lung leukocytes, including specific reductions in CD11c+ CD11b+ myeloid cells (dendritic cells and exudate macrophages), B cells, and CD8+ T cells, and a nonsignificant trend in the reduction of lung neutrophils. Although IL-17A did not alter the total number of CD4 T cells, decreases in the total number of CD4 T cells and CD8 T cells expressing gamma interferon (IFN-γ) were observed in IL-17A(-/-) mice. Lastly, expression of major histocompatibility complex class II (MHC-II) and the costimulatory molecules CD80 and CD86 on CD11c+ CD11b+ myeloid cells was diminished in IL-17A(-/-) mice. Collectively, these data indicate that IL-17A enhances host defenses against a moderately virulent strain of C. neoformans through effects on leukocyte recruitment, IFN-γ production by CD4 and CD8 T cells, and the activation of lung myeloid cells.

Peripheral Mononuclear Response to Antigenic Stimulation in Children with Obese Asthma Phenotype

An investigation of immunopathogenetic mechanisms of obesity-associated asthma may demonstrate novel therapeutic targets. The aim of this study was to compare levels of T-helper lymphocyte (Th)1, Th2, regulatory T lymphocyte (Treg), and Th17 cytokines secreted by peripheral blood mononuclear cell culture (PBMC) in response to nonspecific stimulation in obese and nonobese children with asthma. Obese and nonobese children with asthma aged 5-16 were enrolled into this case-control study consecutively. Age at asthma diagnosis and clinical severity were recorded. A skin prick test was performed. Serum adipokine levels and PBMC supernatant interleukin (IL)-4, IL-10, IL-17, IL-23, interferon (IFN)γ, and transforming growth factor (TGF)-β levels were measured. Mean (±standard deviation) ages of obese (n=28) and nonobese (n=39) children with asthma were 8.7±2.9 and 10.5±3.2, respectively. Asthma symptom score was higher, and age at asthma diagnosis was lower in obese compared with nonobese children with asthma (P=0.03 and P=0.004, respectively). Leptin levels were significantly higher in obese than in nonobese asthma group (P<0.001). IL-10 and IL-17 levels in obese group were significantly lower than in nonobese group (P=0.005 and P=0.017, respectively). On the other hand, TGF-β levels were significantly higher in obese compared with nonobese children with asthma (P=0.015). IL-4, IL-23, and IFNγ levels were not significantly different between the groups (P<0.05 for all). Low IL-10 and high TGF-β levels in obese compared with nonobese children with asthma might indicate lower anti-inflammatory cytokine secretion and Treg function as well as a higher remodeling process in obesity-associated asthma in children.

Staphylococcal vaccine development: review of past failures and plea for a future evaluation of vaccine efficacy not only on staphylococcal infections but also on mucosal carriage

Staphylococcal disease represents a universal burden including acute, life-threatening infections as well as chronic infections usually associated with foreign materials. Infections occur notably in permanent carriers of Staphylococcus aureus. To date, all the attempts to develop an efficacious vaccine against S. aureus have failed. Failures in vaccine clinical trials might be related to a focus on single targets and development of humoral-based vaccines rather than vaccines with a combination of antigens stimulating both humoral and cellular immunity. The end points of these unsuccessful trials were a reduction in mortality or bacteremia, whereas the patient's decolonization was not assessed. Adopting the latter point of view, the aim of this article is to discuss nasal mucosal decolonization as a complementary marker of vaccine efficacy for clinical research in vaccine development.