ADAM8 signaling drives neutrophil migration and ARDS severity

Acute respiratory distress syndrome (ARDS) results in catastrophic lung failure and has an urgent, unmet need for improved early recognition and therapeutic development. Neutrophil influx is a hallmark of ARDS and is associated with the release of tissue-destructive immune effectors, such as matrix metalloproteinases (MMPs) and membrane-anchored metalloproteinase disintegrins (ADAMs). Here, we observed using intravital microscopy that Adam8–/– mice had impaired neutrophil transmigration. In mouse pneumonia models, both genetic deletion and pharmacologic inhibition of ADAM8 attenuated neutrophil infiltration and lung injury while improving bacterial containment. Unexpectedly, the alterations of neutrophil function were not attributable to impaired proteolysis but resulted from reduced intracellular interactions of ADAM8 with the actin-based motor molecule Myosin1f that suppressed neutrophil motility. In 2 ARDS cohorts, we analyzed lung fluid proteolytic signatures and identified that ADAM8 activity was positively correlated with disease severity. We propose that in acute inflammatory lung diseases such as pneumonia and ARDS, ADAM8 inhibition might allow fine-tuning of neutrophil responses for therapeutic gain

IL-17+ CD8+ T cell suppression by dimethyl fumarate associates with clinical response in multiple sclerosis

IL-17-producing CD8+ (Tc17) cells are enriched in active lesions of patients with multiple sclerosis (MS), suggesting a role in the pathogenesis of autoimmunity. Here we show that amelioration of MS by dimethyl fumarate (DMF), a mechanistically elusive drug, associates with suppression of Tc17 cells. DMF treatment results in reduced frequency of Tc17, contrary to Th17 cells, and in a decreased ratio of the regulators RORC-to-TBX21, along with a shift towards cytotoxic T lymphocyte gene expression signature in CD8+ T cells from MS patients. Mechanistically, DMF potentiates the PI3K-AKT-FOXO1-T-BET pathway, thereby limiting IL-17 and RORγt expression as well as STAT5-signaling in a glutathione-dependent manner. This results in chromatin remodeling at the Il17 locus. Consequently, T-BET-deficiency in mice or inhibition of PI3K-AKT, STAT5 or reactive oxygen species prevents DMF-mediated Tc17 suppression. Overall, our data disclose a DMF-AKT-T-BET driven immune modulation and suggest putative therapy targets in MS and beyond

Identification of microRNAs involved in NOD-dependent induction of pro-inflammatory genes in pulmonary endothelial cells.

The nucleotide-binding oligomerization domain-containing proteins (NOD) 1 and 2 are mammalian cytosolic pattern recognition receptors sensing bacterial peptidoglycan fragments in order to initiate cytokine expression and pathogen host defense. Since endothelial cells are relevant cells for pathogen recognition at the blood/tissue interface, we here analyzed the role of NOD1- and NOD2-dependently expressed microRNAs (miRNAs, miR) for cytokine regulation in murine pulmonary endothelial cells. The induction of inflammatory cytokines in response to NOD1 and NOD2 was confirmed by increased expression of tumour necrosis factor (Tnf)-α and interleukin (Il)-6. MiRNA expression profiling revealed NOD1- and NOD2-dependently regulated miRNA candidates, of which miR-147-3p, miR-200a-3p, and miR-298-5p were subsequently validated in pulmonary endothelial cells isolated from Nod1/2-deficient mice. Analysis of the two down-regulated candidates miR-147-3p and miR-298-5p revealed predicted binding sites in the 3' untranslated region (UTR) of the murine Tnf-α and Il-6 mRNA. Consequently, transfection of endothelial cells with miRNA mimics decreased Tnf-α and Il-6 mRNA levels. Finally, a novel direct interaction of miR-298-5p with the 3' UTR of the Il-6 mRNA was uncovered by luciferase reporter assays. We here identified a mechanism of miRNA-down-regulation by NOD stimulation thereby enabling the induction of inflammatory gene expression in endothelial cells

Genome-wide Chromatin Profiling of Legionella pneumophila-Infected Human Macrophages Reveals Activation of the Probacterial Host Factor TNFAIP2

BACKGROUND: Legionella pneumophila is a causative agent of severe pneumonia. Infection leads to a broad host cell response, as evident, for example, on the transcriptional level. Chromatin modifications, which control gene expression, play a central role in the transcriptional response to L. pneumophila METHODS: We infected human-blood-derived macrophages (BDMs) with L. pneumophila and used chromatin immunoprecipitation followed by sequencing to screen for gene promoters with the activating histone 4 acetylation mark. RESULTS: We found the promoter of tumor necrosis factor alpha-induced protein 2 (TNFAIP2) to be acetylated at histone H4. This factor has not been characterized in the pathology of L. pneumophila TNFAIP2 messenger RNA and protein were upregulated in response to L. pneumophila infection of human-BDMs and human alveolar epithelial (A549) cells. We showed that L. pneumophila-induced TNFAIP2 expression is dependent on the NF-kappaB transcription factor. Importantly, knock down of TNFAIP2 led to reduced intracellular replication of L. pneumophila Corby in A549 cells. CONCLUSIONS: Taken together, genome-wide chromatin analysis of L. pneumophila-infected macrophages demonstrated induction of TNFAIP2, a NF-kappaB-dependent factor relevant for bacterial replication

Current concepts in chronic inflammatory diseases : Interactions between microbes, cellular metabolism, and inflammation

Recent research indicates that chronic inflammatory diseases, including allergies and autoimmune and neuropsychiatric diseases, share common pathways of cellular and molecular dysregulation. It was the aim of the International von-Behring-Rontgen Symposium (October 16-18, 2014, in Marburg, Germany) to discuss recent developments in this field. These include a concept of biodiversity; the contribution of urbanization, lifestyle factors, and nutrition (eg, vitamin D); and new mechanisms of metabolic and immune dysregulation, such as extracellular and intracellular RNAs and cellular and mitochondrial stress. Epigenetic mechanisms contribute further to altered gene expression and therefore to the development of chronic inflammation. These novel findings provide the foundation for further development of preventive and therapeutic strategies.Peer reviewe

Transcriptomic comparison of primary human lung cells with lung tissue samples and the human A549 lung cell line highlights cell type specific responses during infections with influenza A virus

Abstract Influenza A virus (IAV) causes pandemics and annual epidemics of severe respiratory infections. A better understanding of the molecular regulation in tissue and cells upon IAV infection is needed to thoroughly understand pathogenesis. We analyzed IAV replication and gene expression induced by IAV strain H3N2 Panama in isolated primary human alveolar epithelial type II cells (AECIIs), the permanent A549 adenocarcinoma cell line, alveolar macrophages (AMs) and explanted human lung tissue by bulk RNA sequencing. Primary AECII exhibit in comparison to AM a broad set of strongly induced genes related to RIG-I and interferon (IFN) signaling. The response of AECII was partly mirrored in A549 cells. In human lung tissue, we observed induction of genes unlike in isolated cells. Viral RNA was used to correlate host cell gene expression changes with viral burden. While relative induction of key genes was similar, gene abundance was highest in AECII cells and AM, while weaker in the human lung (due to less IAV replication) and A549 cells (pointing to their limited suitability as a model). Correlation of host gene induction with viral burden allows a better understanding of the cell-type specific induction of pathways and a possible role of cellular crosstalk requiring intact tissue