Marthe S. Paats

Increased IL-17A expression in granulomas and in circulating memory T cells in sarcoidosis

OBJECTIVE Sarcoidosis is a systemic inflammatory disorder characterized by granulomas. Although the aetiology is unknown, sarcoidosis is thought to be mediated by Th1 lymphocytes. Recently, IL-17A has been implicated in granuloma formation in various diseases, including tuberculosis. Therefore, we hypothesized that Th17 cells play a role in sarcoidosis, paralleling recent findings in autoimmune diseases such as RA. The aim of our study was to investigate the role of Th17 cells in sarcoidosis. METHODS T cells were investigated by intracellular flow cytometry and immunohistochemistry, in blood, bronchoalveolar lavages (BALs) and bronchial mucosal biopsies from a cohort of newly diagnosed sarcoidosis patients and healthy controls. RESULTS Circulating memory CD4(+) T-cell populations of sarcoidosis patients contained significantly increased proportions of IL-17A(+) cells when compared with healthy controls. Interestingly, proportions of IL-17A/IFN-γ and IL-17A/IL-4 double-producing cells were significantly increased in blood of sarcoidosis patients and were present in substantial numbers in BAL. In granuloma-containing, but not in non-granulomatous sarcoidosis biopsies, we found significantly increased numbers of IL-17A(+) T cells, located in and around granulomas throughout the lamina propria. IL-22(+) T cells were increased in the subepithelial layer. CONCLUSIONS Enhanced IL-17A expression in granulomas and the presence of IL-17A(+), IL-17A(+)IFN-γ(+) and IL-17A(+)IL-4(+)memory Th cells in the circulation and BAL indicate Th17 cell involvement in granuloma induction or maintenance in sarcoidosis. Therefore, neutralization of IL-17A activity may be a novel strategy to treat sarcoidosis.

Incidence of viral respiratory pathogens causing exacerbations in adult cystic fibrosis patients.

Abstract Respiratory infections caused by respiratory viruses are common in paediatric cystic fibrosis (CF) patients and are associated with increased morbidity. There is only little data on the incidence of viral respiratory pathogens causing exacerbations in the adult CF patient population. In this observational pilot study we show, by using molecular as well as conventional techniques for viral isolation, that during 1 y a viral pathogen could be isolated in 8/24 (33%) adult CF patients who presented with a pulmonary exacerbation. This result shows that there is a considerable incidence of viral pathogens in pulmonary exacerbations in adult CF patients. Newly identified viruses such as pandemic influenza A/H1N1, human metapneumovirus, human bocavirus, and human coronavirus NL63 were not detected in our population, except for 1 human coronavirus NL63.

Local and systemic cytokine profiles in nonsevere and severe community-acquired pneumonia.

Local inflammatory responses in community-acquired pneumonia (CAP) remain insufficiently elucidated, especially in patients with nonsevere CAP. In this study we determined local and systemic cytokine responses in CAP patients and correlated these with disease severity and other clinical parameters. Levels of interleukin (IL)-6, IL-8, IL-10, IL-1&bgr;, tumour necrosis factor-&agr;, interferon (IFN)-&ggr;, IL-22, IL-17A and IL-4 were determined in bronchoalveolar lavage fluid and serum of 20 CAP patients upon admission and 10 healthy individuals. Systemic cytokine levels were also measured on days 7 and 30. In bronchoalveolar lavage fluid of CAP patients, levels of IL-6, IL-8 and IFN-&ggr; were significantly increased compared with healthy individuals, but no correlations with disease severity were found. Systemic levels of IL-6, IL-10 and IFN-&ggr; were significantly higher in severe CAP patients than in nonsevere CAP patients and healthy individuals. Moreover, these cytokines showed a significant correlation with the pneumonia severity index. In the total group of CAP patients, systemic IL-8 and IL-22 levels were also increased compared with healthy individuals. We therefore conclude that IL-6, IL-10 and IFN-&ggr; are important cytokines in CAP, although differences in disease severity upon admission are only reflected by systemic levels of these cytokines.

Systemic CD4+ and CD8+ T-cell cytokine profiles correlate with GOLD stage in stable COPD.

Chronic obstructive pulmonary disease (COPD) is associated with pulmonary and systemic inflammation. Both CD4+ and CD8+ T-lymphocytes play a key role in COPD pathogenesis, but cytokine profiles in circulating T-lymphocytes have not been well characterised. Here we report the analysis of peripheral blood T-cells from 30 stable COPD patients and 10 healthy never-smokers for interferon (IFN)-&ggr;, interleukin (IL)-4, tumour necrosis factor (TNF)-&agr; and the T-helper 17 cytokines IL-17A, IL-17F and IL-22 by intracellular flow cytometry. We found significantly increased proportions of IFN-&ggr;+ and TNF-&agr;+ CD8+ T-cells in COPD patients, when compared with healthy controls. This was most evident in patients with less severe disease. In contrast, expression profiles in circulating CD4+ T-cells were similar in COPD patients and healthy controls for all cytokines tested, except for IL-17F. COPD patients with more severely reduced diffusing capacity had lower proportions of IL-17A+ CD4+ T-cells. Proportions of IL-22+ cells in the CD4+ memory T-cell population were significantly increased in active smokers, when compared with past smokers. Collectively, this comprehensive cytokine analysis of circulating T-cells in COPD patients revealed a correlation for CD8+ T-cells between Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage and IFN-&ggr; or TNF-&agr; expression, but not for CD4+ T-cells.

T helper 17 cells are involved in the local and systemic inflammatory response in community-acquired pneumonia

Background Recent findings in mouse models suggest that T helper (Th)17 cells, characterised by production of interleukin (IL)-17A and IL-22, are involved in the immunopathogenesis of pneumonia. Objective In this study, we aimed to identify the involvement of Th17 cells in human community-acquired pneumonia (CAP). Design Within 24 h of admission, T cells from peripheral blood (n=39) and bronchoalveolar lavage (BAL, n=20) of CAP patients and of 10 healthy individuals were analysed by intracellular flow cytometry for the production of various cytokines, including IL-17A and IL-22. Peripheral blood T cells were also analysed 7 and 30 days after admission. Th17 cytokine profiles were correlated with pneumonia severity index and microbial aetiology. Results In the BAL of CAP patients, proportions of IL-17A and IL-22 single positive, as well as IL-17A/IL-22 double positive CD4 T cells were significantly increased compared with healthy individuals. Significantly increased proportions of IL-17A/IL-22 double positive CD4 T cells in BAL were found in non-severe and severe CAP patients, as well as in pneumococcal and non-pneumococcal CAP. In the peripheral blood of CAP patients upon admission, we found significantly increased proportions of IL-17A/IL-22 double positive CD4 T cells. One week after admission, the proportions of these double positive cells were still significantly increased in CAP patients compared with healthy individuals. Conclusions These data indicate that Th17 cells are engaged in the local and systemic immune response in human pneumonia. Especially, IL-17A/IL-22 double positive Th17 cells may be involved in the immunopathogenesis of CAP.

Cytokines in nasal lavages and plasma and their correlation with clinical parameters in cystic fibrosis

BACKGROUND Because persistent inflammation plays a dominant role in cystic fibrosis (CF), we assessed systemic and local upper airway responses during and after pulmonary exacerbation. METHODS We followed a cohort of Pseudomonas aeruginosa-infected adult CF patients (n=16) over time in pulmonary exacerbation and in stable disease. Interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-17A, IL-22, interferon-γ and TNFα levels were measured in sputum, nasal lavages and plasma. RESULTS In CF patients IL-6 and IL-10 levels in nasal lavages were significantly increased in exacerbation compared with stable disease. Systemic IL-6 significantly correlated with CRP levels and FEV1 (%predicted), independently of disease status. Systemic IL-10 also correlated significantly with CRP and FEV1 (%predicted), but only in exacerbation. Other cytokines tested did not discriminate between exacerbation and stable disease. CONCLUSIONS Determination of IL-6 and IL-10 in nasal lavages may provide a minimally invasive tool in the assessment of an exacerbation in CF.

Interleukin-17 and T Helper 17 Cells in Mucosal Immunity of the Lung

In all mammals, including humans, the immune system is responsible for the protection against potentially hazardous pathogens, such as bacteria, viruses, parasites and fungi. In this remarkably effective defense system leukocytes, which mediate both innate and adaptive immune responses, play a central role. The innate immune system comprises granulocytes (neutrophils, eosinophils and basophils), natural killer (NK) cells, mast cells and macrophages. These cells are the first line of defense and provide the immediate response against pathogens. Neutrophils and macrophages can eliminate a pathogen directly by phagocytosis. Moreover, their pattern-recognition receptors, recognizing structurally conserved molecules derived from microbes such as bacterial lipopolysaccharides, unmethylated CpG, or viral double-stranded RNA, allow them to respond to a wide variety of microbial invaders, e.g. by producing cytokines that activate T lymphocytes of the adaptive immune system. Acquired or adaptive immunity is characterized by a slower but highly specific immune response. Three major cell types are involved in adaptive immunity: antigen presenting cells (APCs), T lymphocytes and B lymphocytes. Dendritic cells (DCs) are the most potent APCs. They act as messengers between the innate and the adaptive immune system by taking up, processing and presenting antigens to T lymphocytes. In response to presented antigens, T lymphocytes may react in different ways: CD4+ T helper cells produce various cytokines that direct the immune response, whereas CD8+ cytotoxic T cells produce toxic granules that induce death of infected cells. B cells are able to respond to pathogens by terminal differentiation into plasma cells after which they produce large quantities of antibodies. Modulation of B cell function and antibody production by CD4+ T cells is an important step in coordinating immune responses. Upon activation, B cells can migrate to germinal centers, which are specialized structures in secondary lymphoid organs, where they interact with T cells and DCs. Costimulatory signals from T cells then facilitate selection of B cells with high affinity for immunoglobulins and control class switching of the immunoglobulin (Ig) to IgG, IgA and IgE. Following pathogen elimination, lymphocytes leave a lasting legacy of the antigens they have come across represented by memory cells. As a result, lymphocytes are able to mount a faster and stronger immune response in future encounters with the same antigen. Defective T cell function can increase susceptibility to infections, allergies and autoimmune diseases. T