Chronic obstructive pulmonary disease (COPD) is mainly caused by cigarette smoking, and is characterized by an increase in inflammatory cells in the airways and pulmonary tissue. The chemokine receptor CCR6 and its ligand MIP-3α/CCL20 may be involved in the recruitment of these inflammatory cells. To investigate the role of CCR6 in the pathogenesis of COPD, we analyzed the inflammatory responses of CCR6 knockout (KO) and wild-type mice upon cigarette smoke (CS) exposure. Both subacute and chronic exposure to CS induced an increase in cells of the innate and adaptive immune system in the bronchoalveolar lavage, both in CCR6 KO and wild-type mice. However, the accumulation of dendritic cells, neutrophils, and T lymphocytes, which express CCR6, was significantly attenuated in the CCR6 KO mice, compared with their wild-type littermates. In the lung tissue of CCR6 KO mice, there was an impaired increase in dendritic cells, activated CD8+ T lymphocytes, and granulocytes. Moreover, this attenuated inflammatory response in CCR6 KO mice offered a partial protection against pulmonary emphysema, which correlated with an impaired production of MMP-12. Importantly, protein levels of MIP-3α/CCL20, the only chemokine ligand of the CCR6 receptor, and MCP-1/CCL2 were significantly increased upon CS exposure in wild-type, but not in CCR6 KO mice. In contrast, CCR6 deficiency had no effect on the development of airway wall remodeling upon chronic CS exposure. These results indicate that the interaction of CCR6 with its ligand MIP-3α contributes to the pathogenesis of CS-induced pulmonary inflammation and emphysema in this murine model of COPD.

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Expression of miR-223-3p, miR-142-3p, and miR-629-3p is increased in sputum of patients with severe asthma and is linked to neutrophilic airway inflammation, suggesting that these miRNAs contribute to this asthma inflammatory phenotype.

BackgroundInnate lymphoid cells (ILC) are a new family of innate immune cells that have emerged as important regulators of tissue homeostasis and inflammation. However, limited data are available concerning the relative abundance and characteristics of ILC in the human lung.MethodsThe aim of this study was to characterize and enumerate the different ILC subsets in human lung by multi-color flow cytometry.ResultsWithin the CD45+ Lin- CD127+ pulmonary ILC population, we identified group 1 (ILC1), group 2 (ILC2) and group 3 (ILC3) innate lymphoid cells using specific surface markers (i.e. IL12Rβ2, CRTH2 and CD117 respectively) and key transcription factors (i.e. T-bet, GATA-3 and RORγT respectively). Based on the presence of NKp44, ILC3 were further subdivided in natural cytotoxicity receptor (NCR)+ and NCR- ILC3. In addition, we demonstrated the production of signature cytokines IFN-γ, IL-5, IL-17A, IL-22 and GM-CSF in the pulmonary ILC population. Interestingly, we observed a tendency to a higher frequency of NCR- ILC3 in lungs of patients with chronic obstructive pulmonary disease (COPD) compared with controls.ConclusionsWe show that the three main ILC subsets are present in human lung. Importantly, the relative abundance of ILC subsets tended to change in COPD patients in comparison to control individuals.

Dendritic cells (DCs) appear to be strategically implicated in allergic diseases, including asthma. Matrix metalloproteinase (MMP)-9 mediates transmigration of inflammatory leukocytes across basement membranes. This study investigated the role of MMP-9 in airway DC trafficking during allergen-induced airway inflammation. MMP-9 gene deletion affected the trafficking of pulmonary DCs in a specific way: only the inflammatory transmigration of DCs into the airway lumen was impaired, whereas DC-mediated transport of airway Ag to the thoracic lymph nodes remained unaffected. In parallel, the local production of the Th2-attracting chemokine CC chemokine ligand 17/thymus and activation-regulated chemokine, which was highly concentrated in purified lung DCs, fell short in the airways of allergen-exposed MMP-9−/− mice. This was accompanied by markedly reduced peribronchial eosinophilic infiltrates and impaired allergen-specific IgE production. We conclude that the specific absence of MMP-9 activity inhibits the development of allergic airway inflammation by impairing the recruitment of DCs into the airways and the local production of DC-derived proallergic chemokines.

The S aureus-derived protein SplD is a potent allergen of S aureus and induces a T2-biased inflammatory response in the airways in an IL-33-dependent but TRL4-independent manner. The soluble ST2 receptor could be an efficient strategy to interfere with SplD-induced T2 inflammation but does not prevent the allergic sensitization.

Dendritic cells (DC) have a central role in the initiation of adequate immune responses. They recognize pathogens by means of Toll-like receptors (TLR) and link innate to adaptive immune responses by releasing proinflammatory cytokines and inducing T cell proliferation. We conducted this study to evaluate the expression and function of TLR on human lung DC subsets and to study their T cell stimulatory capacity. TLR gene expression by human pulmonary DC was evaluated by RT-PCR, while protein expression was analyzed by flow cytometry. We investigated cytokine release by DC in response to different TLR ligands. T cell stimulatory capacity was evaluated by mixed leukocyte reactions of purified lung DC with allogeneic T cells. Myeloid dendritic cells type 1 (mDC1) and myeloid dendritic cells type 2 (mDC2) express mRNA transcripts for TLR1, TLR2, TLR3, TLR4, TLR6, and TLR8. Flow cytometric analysis demonstrated high TLR2 protein expression for mDC1 and moderate TLR4 expression for mDC2. mDC1 and mDC2 release proinflammatory cytokines (TNF-alpha, IL-1beta, IL-6, and IL-8) in response to TLR2 and TLR4 ligands. TLR3 ligands induce cytokine release in mDC1, but not in mDC2. Plasmacytoid DC (pDC) express TLR7 and TLR9 and release proinflammatory cytokines in response to imiquimod and IFN-alpha in response to CpG oligonucleotides. mDC1 are strong inducers of T cell proliferation, while pDC hardly induce any T cell proliferation. mDC2 have an intermediate T cell-stimulatory capacity. Our results show divergent roles for the different human lung DC subsets, both in innate and adaptive immune responses.

We highlight a role for miR-218-5p in the pathogenesis of COPD.