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IFN-? induction by neutrophil-derived IL-17A homodimer augments pulmonary antibacterial defense.

ABSTRACT: The role of interleukin-17A (IL-17A) in host defense against Legionella pneumophila remains elusive. To address this issue, we used Il17a(-/-), Il17f(-/-), and Il17a/Il17f(-/-) mice on a C57Bl/6 (non-permissive) background and IL-17 neutralizing Abs in mice on an A/J (permissive) background. Higher bacterial (L. pneumophila) counts in the lung and blood along with reduced neutrophil recruitment were detected in Il17a(-/-), but not Il17f(-/-), mice. We found that neutrophils produce IL-17A homodimer (IL-17A) during L. pneumophila infection, and hematopoietic cell-derived IL-17A is known to be important for bacterial clearance. Thus, intratracheal administration of wild-type neutrophils or recombinant IL-17A restored bacterial clearance and neutrophil recruitment in Il17a(-/-) mice. Furthermore, neutrophil-depleted Rag2(-/-) and Rag2/Il-2r?(-/-) mice exhibited increased bacterial burden, reduced neutrophil influx and IL-17A production in the lung. Recombinant IFN-? administration in Il17a(-/-) mice augmented bacterial elimination, whereas IL-17A administration in Ifn?(-/-) mice did not augment bacterial clearance. IFN-? is produced by T cells, but not neutrophils or macrophages, suggesting that neutrophil-derived IL-17A induces IFN-? in a paracrine fashion. Human pneumonic lungs and human neutrophils challenged with L. pneumophila exhibited increased numbers of IL-17A producing cells. These findings display a novel function of neutrophil-derived IL-17A in antibacterial defense via the induction of IFN-? in a paracrine manner.

SUBMITTER: Cai S

PROVIDER: S-EPMC4785101 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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IFN-γ induction by neutrophil-derived IL-17A homodimer augments pulmonary antibacterial defense.

Cai S S Batra S S Langohr I I Iwakura Y Y Jeyaseelan S S

Mucosal immunology 20150909 3

The role of interleukin-17A (IL-17A) in host defense against Legionella pneumophila remains elusive. To address this issue, we used Il17a(-/-), Il17f(-/-), and Il17a/Il17f(-/-) mice on a C57Bl/6 (non-permissive) background and IL-17 neutralizing Abs in mice on an A/J (permissive) background. Higher bacterial (L. pneumophila) counts in the lung and blood along with reduced neutrophil recruitment were detected in Il17a(-/-), but not Il17f(-/-), mice. We found that neutrophils produce IL-17A homodi ...[more]

PMID: 26349661

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Project description:The clinical features of psoriasis, characterized by sharply demarcated scaly erythematous plaques, are typically so distinctive that a diagnosis can easily be made on these grounds alone. However, there is great variability in treatment response between individual patients, and this may reflect heterogeneity of inflammatory networks driving the disease. In this study, whole-genome transcriptional profiling was used to characterize inflammatory and cytokine networks in 62 lesional skin samples obtained from patients with stable chronic plaque psoriasis. We were able to stratify lesions according to their inflammatory gene expression signatures, identifying those associated with strong (37% of patients), moderate (39%) and weak inflammatory infiltrates (24%). Additionally, we identified differences in cytokine signatures with heightened cytokine-response patterns in one sub-group of lesions (IL-13-strong; 50%) and attenuation of these patterns in a second sub-group (IL-13-weak; 50%). These sub-groups correlated with the composition of the inflammatory infiltrate, but were only weakly associated with increased risk allele frequency at some psoriasis susceptibility loci (e.g., REL, TRAF3IP2 and NOS2). Our findings highlight variable points in the inflammatory and cytokine networks known to drive chronic plaque psoriasis. Such heterogeneous aspects may shape clinical course and treatment responses, and can provide avenues for development of personalized treatments. We used Affymetrix microarrays to evaluate genome-wide expression in primary human keratinocytes exposed to cytokines. Cytokine activity signatures were used to interpret the shifts in gene expression that occur in psoriasis plaques relative to normal uninvolved skin. Primary keratinocytes from three donors (subjects 1, 2, and 3) were obtained and were either untreated (control) or exposed to cytokines (IL-4, IL-13, IFN-alpha, IFN-gamma and TNF). For the IL17A samples, primary keratinocytes were obtained from six donors, with cells derived from three donors treated with IL-17A and cells derived from the other three donors left untreated (i.e., unpaired control samples).

Dataset Information

IFN-? induction by neutrophil-derived IL-17A homodimer augments pulmonary antibacterial defense.

Publications

IFN-γ induction by neutrophil-derived IL-17A homodimer augments pulmonary antibacterial defense.

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