Extravasation of monocytes into tissue and to the site of injury is a fundamental immunological process, which requires rapid responses via post translational modifications (PTM) of proteins. Protein ...arginine methyltransferase 7 (PRMT7) is an epigenetic factor that has the capacity to mono-methylate histones on arginine residues. Here we show that in chronic obstructive pulmonary disease (COPD) patients, PRMT7 expression is elevated in the lung tissue and localized to the macrophages. In mouse models of COPD, lung fibrosis and skin injury, reduced expression of PRMT7 associates with decreased recruitment of monocytes to the site of injury and hence less severe symptoms. Mechanistically, activation of NF-κB/RelA in monocytes induces PRMT7 transcription and consequential mono-methylation of histones at the regulatory elements of RAP1A, which leads to increased transcription of this gene that is responsible for adhesion and migration of monocytes. Persistent monocyte-derived macrophage accumulation leads to ALOX5 over-expression and accumulation of its metabolite LTB4, which triggers expression of ACSL4 a ferroptosis promoting gene in lung epithelial cells. Conclusively, inhibition of arginine mono-methylation might offer targeted intervention in monocyte-driven inflammatory conditions that lead to extensive tissue damage if left untreated.
Increased expression of pulmonary ACE2, the SARS-CoV-2 receptor, could contribute to increased infectivity of COVID-19 in patients with diabetes, but ACE2 expression has not been studied in lung ...tissue of subjects with diabetes. We therefore studied ACE2 mRNA and protein expression in lung tissue samples of subjects with and without diabetes that were collected between 2002 and 2020 from patients undergoing lobectomy for lung tumors. For RT-PCR analyses, samples from 15 subjects with diabetes were compared with 91 randomly chosen control samples. For immunohistochemical staining, samples from 26 subjects with diabetes were compared with 66 randomly chosen control samples. mRNA expression of ACE2 was measured by quantitative RT-PCR. Protein levels of ACE2 were visualized by immunohistochemistry on paraffin-embedded lung tissue samples and quantified in alveolar and bronchial epithelium. Pulmonary ACE2 mRNA expression was not different between subjects with or without diabetes. In contrast, protein levels of ACE2 were significantly increased in both alveolar tissue and bronchial epithelium of patients with diabetes compared with control subjects, independent of smoking, chronic obstructive pulmonary disease, BMI, renin-angiotensin-aldosterone system inhibitor use, and other potential confounders. To conclude, we show increased bronchial and alveolar ACE2 protein expression in patients with diabetes. Further research is needed to elucidate whether upregulation of ACE2 expression in airways and lungs has consequences on infectivity and clinical outcomes of COVID-19.
Acetaminophen (APAP) intoxication is the foremost cause of drug‐induced liver failure in developed countries. The only pharmacologic treatment option, N‐acetylcysteine (NAC), is not effective for ...patients who are admitted too late and/or who have excessive liver damage, emphasizing the need for alternative treatment options. APAP intoxication results in hepatocyte death and release of danger signals, which further contribute to liver injury, in part by hepatic monocyte/macrophage infiltration and activation. Metallothionein (MT) 1 and 2 have important danger signaling functions and might represent novel therapeutic targets in APAP overdose. Therefore, we evaluated hepatic MT expression and the effect of anti‐MT antibodies on the transcriptional profile of the hepatic macrophage population and liver injury following APAP overdose in mice. Hepatic MT expression was significantly induced in APAP‐intoxicated mice and abundantly present in human livers. APAP intoxication in mice resulted in increased serum transaminase levels, extended necrotic regions on liver histology and induced expression of proinflammatory markers, which was significantly less pronounced in mice treated with anti‐MT antibodies. Anti‐MT antibody therapy attenuated proinflammatory macrophage polarization, as demonstrated by RNA sequencing analyses of isolated liver macrophages and in LPS‐stimulated bone marrow‐derived macrophages. Importantly, NAC and anti‐MT antibodies were equally effective whereas administration of anti‐MT antibody in combination with NAC exceeded the efficiency of both monotherapies in APAP‐induced liver injury (AILI). We conclude that the neutralization of secreted MTs using a monoclonal antibody is a novel therapeutic strategy as mono‐ or add‐on therapy for AILI. In addition, we provide evidence suggesting that MTs in the extracellular environment are involved in macrophage polarization.
Graphical
Anti‐metallothionein antibody therapy reduces liver injury in experimental acetaminophen overdose.
The delivery of RNA across biological barriers can be achieved by encapsulation in lipid nanoparticles (LNPs). Cationic amphiphilic drugs (CADs) are pharmacologically diverse compounds with ionizable ...lipid-like features. In this work, we applied CADs as a fifth component of state-of-the-art LNPs via microfluidic mixing. Improved cytosolic delivery of both siRNA and mRNA was achieved by partly replacing the cholesterol fraction of LNPs with CADs. The LNPs could cross the mucus layer in a mucus-producing air–liquid interface model of human primary bronchial epithelial cells following nebulization. Moreover, CAD-LNPs demonstrated improved epithelial and endothelial targeting following intranasal administration in mice, without a marked pro-inflammatory signature. Importantly, quantification of the CAD-LNP molar composition, as demonstrated for nortriptyline, revealed a gradual leakage of the CAD from the formulation during LNP dialysis. Altogether, these data suggest that the addition of a CAD prior to the rapid mixing process might have an impact on the composition, structure, and performance of LNPs.
Receptor-interacting protein kinase 1 (RIPK1) is a key mediator of regulated cell death (including apoptosis and necroptosis) and inflammation, both drivers of COPD pathogenesis. We aimed to define ...the contribution of RIPK1 kinase-dependent cell death and inflammation in the pathogenesis of COPD.
We assessed
expression in single-cell RNA sequencing (RNA-seq) data from human and mouse lungs, and validated RIPK1 levels in lung tissue of COPD patients
immunohistochemistry. Next, we assessed the consequences of genetic and pharmacological inhibition of RIPK1 kinase activity in experimental COPD, using
kinase-deficient mice and the RIPK1 kinase inhibitor GSK'547.
expression increased in alveolar type 1 (AT1), AT2, ciliated and neuroendocrine cells in human COPD. RIPK1 protein levels were significantly increased in airway epithelium of COPD patients compared with never-smokers and smokers without airflow limitation. In mice, exposure to cigarette smoke (CS) increased
expression similarly in AT2 cells, and further in alveolar macrophages and T-cells. Genetic and/or pharmacological inhibition of RIPK1 kinase activity significantly attenuated airway inflammation upon acute and subacute CS exposure, as well as airway remodelling, emphysema, and apoptotic and necroptotic cell death upon chronic CS exposure. Similarly, pharmacological RIPK1 kinase inhibition significantly attenuated elastase-induced emphysema and lung function decline. Finally, RNA-seq on lung tissue of CS-exposed mice revealed downregulation of cell death and inflammatory pathways upon pharmacological RIPK1 kinase inhibition.
RIPK1 kinase inhibition is protective in experimental models of COPD and may represent a novel promising therapeutic approach.
Objectives
Innate lymphoid cells (ILCs) secrete cytokines, such as IFN‐γ, IL‐13 and IL‐17, which are linked to chronic obstructive pulmonary disease (COPD). Here, we investigated the role of ...pulmonary ILCs in COPD pathogenesis.
Methods
Lung ILC subsets in COPD and control subjects were quantified using flow cytometry and associated with clinical parameters. Tissue localisation of ILC and T‐cell subsets was determined by immunohistochemistry. Mice were exposed to air or cigarette smoke (CS) for 1, 4 or 24 weeks to investigate whether pulmonary ILC numbers and activation are altered and whether they contribute to CS‐induced innate inflammatory responses.
Results
Quantification of lung ILC subsets demonstrated that ILC1 frequency in the total ILC population was elevated in COPD and was associated with smoking and severity of respiratory symptoms (COPD Assessment Test CAT score). All three ILC subsets localised near lymphoid aggregates in COPD. In the COPD mouse model, CS exposure in C57BL/6J mice increased ILC numbers at all time points, with relative increases in ILC1 in bronchoalveolar lavage (BAL) fluid. Importantly, CS exposure induced increases in neutrophils, monocytes and dendritic cells that remained elevated in Rag2/Il2rg‐deficient mice that lack adaptive immune cells and ILCs. However, CS‐induced CXCL1, IL‐6, TNF‐α and IFN‐γ levels were reduced by ILC deficiency.
Conclusion
The ILC1 subset is increased in COPD patients and correlates with smoking and severity of respiratory symptoms. ILCs also increase upon CS exposure in C57BL/6J mice. In the absence of adaptive immunity, ILCs contribute to CS‐induced pro‐inflammatory mediator release, but are redundant in CS‐induced innate inflammation.
In this article, we investigated the role of pulmonary innate lymphoid cells (ILCs) in the pathogenesis of chronic obstructive pulmonary disease (COPD). We found that the ILC1 subset is increased in COPD patients and correlates with smoking and severity of respiratory symptoms. In C57BL/6 mice, ILCs increase upon cigarette smoke (CS) exposure. In the absence of adaptive immunity, ILCs contribute to CS‐induced pro‐inflammatory mediator release, but they are redundant in CS‐induced innate inflammation.
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