Yves Sibille

LPS induces IL-10 production by human alveolar macrophages via MAPKinases- and Sp1-dependent mechanisms.

BackgroundIL-10 is a cytokine mainly produced by macrophages that plays key roles in tolerance to inhaled antigens and in lung homeostasis. Its regulation in alveolar macrophages (HAM), the resident lung phagocytes, remains however unknown.MethodsThe present study investigated the role of intracellular signalling and transcription factors controlling the production of IL-10 in LPS-activated HAM from normal nonsmoking volunteers.ResultsLPS (1–1000 pg/ml) induced in vitro IL-10 production by HAM, both at mRNA and protein levels. LPS also activated the phosphorylation of ERK, p38 and JNK MAPkinases (immunoblots) and Sp-1 nuclear activity (EMSA). Selective inhibitors of MAPKinases (respectively PD98059, SB203580 and SP600125) and of Sp-1 signaling (mithramycin) decreased IL-10 expression in HAM. In addition, whilst not affecting IL-10 mRNA degradation, the three MAPKinase inhibitors completely abolished Sp-1 activation by LPS in HAM.ConclusionThese results demonstrate for the first time that expression of IL-10 in lung macrophages stimulated by LPS depends on the concomitant activation of ERK, p38 and JNK MAPKinases, which control downstream signalling to Sp-1 transcription factor. This study further points to Sp-1 as a key signalling pathway for IL-10 expression in the lung.

Lung mucosal immunity: immunoglobulin‐A revisited

Mucosal defence mechanisms are critical in preventing colonization of the respiratory tract by pathogens and penetration of antigens through the epithelial barrier. Recent research has now illustrated the active contribution of the respiratory epithelium to the exclusion of microbes and particles, but also to the control of the inflammatory and immune responses in the airways and in the alveoli. Epithelial cells also mediate the active transport of polymeric immunoglobulin-A from the lamina propria to the airway lumen through the polymeric immunoglobulin receptor. The role of IgA in the defence of mucosal surfaces has now expanded from a limited role of scavenger of exogenous material to a broader protective function with potential applications in immunotherapy. In addition, the recent identification of receptors for IgA on the surface of blood leukocytes and alveolar macrophages provides an additional mechanism of interaction between the cellular and humoral immune systems at the level of the respiratory tract.We read through the Review by PILETTE et al. [1] with extreme interest and would like to add a contribution to the subject of airways immunity in chronic obstructive pulmonary disease (COPD). For a long time, we have witnessed, at least in Italy, the predominance of the notion that all COPD patients have a certain degree of immune deficiency as a basic pathogenetic mechanism, since they experience recurrent bronchitis exacerbations. Scientific evidence of true general or local immune defects in COPD is, in our opinion, inconclusive, although we fully agree on the point made by the authors that all the studies in the literature share methodological limitations, both in sampling and analysis techniques and in selection of patients. In our experience, different immune components can appear either similar to controls or increased (as a likely consequence of repeated stimulation by exacerbations or chronic bacterial colonization of the airways), or decreased in a specific group of COPD patients. Indeed, we recently reported decreased numbers of CD3 and CD8 lymphocytes in the bronchial biopsies of severe COPD patients, associated with an increase of neutrophils and macrophages [2]. With particular regard to immunoglobulin (Ig)-A, we found only an insignificant increase in patients with mild COPD who had never smoked [3], and a high increase in severe but clinically stable COPD patients with chronic tracheostomy and a high level of bacterial colonization [4]. The experience with tracheostomized COPD patients is very interesting because they provide a model of bacteria/host interaction in which the role of immunity can be evaluated prospectively. The presence of high levels of IgA in bronchial aspirates could, in part, justify the relatively low rate of lower respiratory tract infections in these patients after discharge from hospital [5]. We appreciated the long and accurate list of defence mechanisms in the respiratory tract reported by the authors, which clearly shows that specific immune functions are only a part of the airways protection system. Indirect proof that immunoglobulins are only a part, albeit an important part, of mucosal immunity, comes from studies on the stimulation of mucosaassociated lymphoid tissues with oral vaccines or bacterial extracts, which have been demonstrated to reduce the impact of bronchitis exacerbations, at least in mild-to-moderate chronic obstructive pulmonary disease [6]. The mechanisms of action were reflected in an increase of immunoglobulin-A in the airways9 fluids, but more solid evidence, from a biological point of view, was the activation of alveolar macrophages [7]. In our opinion, the potential of oral bacterial extracts to stimulate immunoglobulin-A production in the airways should be further investigated. In conclusion, we would once again like to stress that the impairment of defence systems in the airways is not simply a question of specific immunity, and that a clinically relevant imbalance in chronic obstructive pulmonary disease must be evaluated within a complex defence network concept, rather than in a simple cause/effect perspective.

Asthma phenotypes and IgE responses.

The discovery of IgE represented a major breakthrough in allergy and asthma research, whereas the clinical interest given to IgE in asthma has been blurred until the arrival of anti-IgE biotherapy. Novel facets of the complex link between IgE and asthma have been highlighted by the effect of this treatment and by basic research. In parallel, asthma phenotyping recently evolved to the concept of endotypes, relying on identified/suspected pathobiological mechanisms to phenotype patients, but has not yet clearly positioned IgE among biomarkers of asthma. In this review, we first summarise recent knowledge about the regulation of IgE production and its main receptor, FcεRI. In addition to allergens acting as classical IgE inducers, viral infections as well as air pollution may trigger the IgE pathway, notably resetting the threshold of IgE sensitivity by regulating FcεRI expression. We then analyse the place of IgE in different asthma endo/phenotypes and discuss the potential interest of IgE among biomarkers in asthma. We summarise regulation of IgE production, and discuss IgE in different asthma endo/phenotypes and among biomarkers http://ow.ly/TLxcW

Modulation of Intracellular Growth of Listeria monocytogenes in Human Enterocyte Caco-2 Cells by Interferon-γ and Interleukin-6: Role of Nitric Oxide and Cooperation with Antibiotics

The influence of interferon (IFN)-gamma and interleukin (IL)-6 on the intracellular growth of Listeria monocytogenes phagocytosed from the apical pole was examined in polarized Caco-2 cells. IFN-gamma (from the apical pole) and IL-6 (from the basolateral pole) considerably reduced the bacterial intracellular growth, an effect largely abolished by l-monomethyl arginine. Both cytokines caused overexpression of inducible nitric oxide synthase. IL-6, but not IFN-gamma, caused a partial restriction of L. monocytogenes in phagosomes and largely prevented the cytosolic forms from being surrounded by actin. Ampicillin was bacteriostatic in unstimulated cells but modestly bactericidal in cells treated with IFN-gamma and IL-6. Azithromycin (a macrolide) was fairly bactericidal and sparfloxacin (a fluoroquinolone) highly bactericidal in all situations. IFN-gamma and IL-6 may therefore be important determinants in the protection of epithelial cells from intracellular multiplication of L. monocytogenes. Ampicillin may fail in their absence, requiring the use of other antibiotics such as the fluoroquinolones.

Diagnostic Accuracy and Safety of CT-Guided Percutaneous Transthoracic Needle Biopsies: 14-Gauge versus 22-Gauge Needles.

PURPOSEnTo compare the diagnostic accuracy and safety of a 14-gauge core needle versus a 22-gauge fine needle in the evaluation of thoracic lesions by CT-guided percutaneous transthoracic needle biopsy (TTNB).nnnMATERIALS AND METHODSnMedical charts of all patients who underwent CT-guided percutaneous transthoracic core-needle biopsies (CNBs) with a 14-gauge Spirotome device (99 patients, 102 procedures) and fine-needle biopsies (FNBs) with a 22-gauge Rotex needle (92 patients, 102 procedures) between 2007 and 2013 at a single academic institution were retrospectively reviewed. Variables that could influence diagnostic accuracy and safety were collected.nnnRESULTSnThe overall and cancer-specific diagnostic accuracy rates were 90% and 94%, respectively, with CNB, versus 82% and 89% with FNB. Precise cancer type/subtype was provided by 97% of CNBs versus 65% of FNBs (P < .001). In patients with lung cancer considered for targeted therapy, biomarker analyses were feasible in 80% of CNBs versus 0% of FNBs (P < .001). The rate of pneumothorax was significantly higher with CNB versus FNB (31% vs 19%; P = .004), but chest tube insertion rates were similar (10% vs 11%, respectively). Major bleeding complications occurred in 1% of CNBs versus 2% of FNBs and were associated with one death in the CNB group.nnnCONCLUSIONSnPercutaneous transthoracic CNB with a 14-gauge Spirotome needle provided better characterization of cancer lesions and allowed biomarker analyses without a significant increase in major procedural complications.

L'immunoglobuline-A module la production de cytokines induites par le LPS dans les Macrophages Alvéolaires via sa liaison au "core" du LPS.

Introductionxa0: Dans le poumon, une interaction physiologique s’etablit continuellement entre les HAM (Human Alveolar Macrophages) et l’IgA, l’immunoglobuline la plus abondante des muqueuses presente a ce niveau surtout sous forme polymerique (pIgA). Des effets pro- et anti-inflammatoires de l’IgA sur les HAM ont ete decrits, mais les mecanismes impliquees restent mal connus. En particulier, les mecanismes de regulation de la production d’IL- 10 et de l’IL-8, deux cytokines cles des reponses inflammatoires des muqueuses, ont ete investigues dans les HAMs en reponse au lipopolysaccharide (LPS). Methodesxa0: Les HAM obtenus par lavage bronchoalveolaire de sujets volontaires non fumeurs ont ete stimules par la pIgA (1xa0mg/ml) et/ou le LPS (1xa0µg/ml). Les productions d’IL-10 et IL-8 ont ete evaluees par ELISA et PCR en temps reel. L’implication des MAPkinases (ERK, p38 et JNK) a ete etudiee par l’utilisation d’inhibiteurs selectifs et par Western Blotting. L’interaction entre LPS et IgA a ensuite ete evaluee par electrophorese, western blot. Resultatsxa0: Un effet inhibiteur de l’IgA est observe sur la production d’IL-10 et IL-8 induite par le LPS dans les HAM. L’activation intracellulaire des MAPkinases par l’IgA est similaire en presence ou en absence de LPS. Les facteurs suivants sont observes pour l’effet inhibiteur de l’IgA:(1) la concentration d’IgA doit etre superieure a 100xa0µg/ml, (2) le LPS et l’IgA doivent etre presents de maniere concomitante et (3) l’inhibition de l’internalisation par la cytochalasine D, n’interfere pas avec l’effet de l’IgA sur le LPS. Une liaison de l’IgA au LPS a ete confirmee par d’electrophorese native impliquant le core du LPS. L’utilisation d’un antiCD14 mAb, montre aussi qu’en liant le LPS, l’IgA neutralise l’activation de la cellule par le CD14. Conclusionxa0: Ces resultats indiquent que l’IgA interfere avec les mecanismes d’activation macrophagique par l’endotoxine, en particulier pour la production de cytokines comme l’IL-10 et l’IL-8. Cette immuno-modulation qui implique, au moins en partie, une liaison du LPS par IgA, pourrait constituer un mecanisme important de controle des reponses pulmonaires innees.