MicroRNA-1 protects the endothelium in acute lung injury

Acute lung injury (ALI) and its most severe form, acute respiratory distress syndrome (ARDS), cause severe endothelial dysfunction in the lung, and vascular endothelial growth factor (VEGF) is elevated in ARDS. We found that the levels of a VEGF-regulated microRNA, microRNA-1 (miR-1), were reduced in the lung endothelium after acute injury. Pulmonary endothelial cell-specific (EC-specific) overexpression of miR-1 protected the lung against cell death and barrier dysfunction in both murine and human models and increased the survival of mice after pneumonia-induced ALI. miR-1 had an intrinsic protective effect in pulmonary and other types of ECs; it inhibited apoptosis and necroptosis pathways and decreased capillary leak by protecting adherens and tight junctions. Comparative gene expression analysis and RISC recruitment assays identified miR-1 targets in the context of injury, including phosphodiesterase 5A (PDE5A), angiopoietin-2 (ANGPT2), CNKSR family member 3 (CNKSR3), and TNF-α-induced protein 2 (TNFAIP2). We validated miR-1-mediated regulation of ANGPT2 in both mouse and human ECs and found that in a 119-patient pneumonia cohort, miR-1 correlated inversely with ANGPT2. These findings illustrate a previously unknown role of miR-1 as a cytoprotective orchestrator of endothelial responses to acute injury with prognostic and therapeutic potential.

Platelet-derived TLT-1 promotes tumor progression by suppressing CD8+ T cells

Current understanding of tumor immunosuppressive mechanisms forms the basis for modern day immunotherapies. Immunoregulatory role of platelets in cancer remains largely elusive. Platelets from non-small cell lung cancer (NSCLC) patients revealed a distinct activation phenotype. TREM-like transcript 1 (TLT-1), a platelet protein, was increased along with enhanced extracellular release from NSCLC platelets. The increased platelet TLT-1 was also evident in humanized mice with patient-derived tumors. In immunocompetent mice with syngeneic tumors, TLT-1 binding to T cells, in vivo, led to suppression of CD8 T cells, promoting tumor growth. We identified direct interaction between TLT-1 and CD3ε on T cells, implicating the NF-κB pathway in CD8 T cell suppression. Anti-TLT-1 antibody rescued patients' T cells from platelet-induced suppression ex vivo and reduced tumors in mice in vivo. Clinically, higher TLT-1 correlated with reduced survival of NSCLC patients. Our findings thus identify TLT-1 as a platelet-derived immunosuppressor that suppresses CD8 T cells and demonstrate its therapeutic and prognostic significance in cancer.

Coronavirus Lung Infection Impairs Host Immunity against Secondary Bacterial Infection by Promoting Lysosomal Dysfunction

Postviral bacterial infections are a major health care challenge in coronavirus infections, including COVID-19; however, the coronavirus-specific mechanisms of increased host susceptibility to secondary infections remain unknown. In humans, coronaviruses, including SARS-CoV-2, infect lung immune cells, including alveolar macrophages, a phenotype poorly replicated in mouse models of SARS-CoV-2. To overcome this, we used a mouse model of native murine β-coronavirus that infects both immune and structural cells to investigate coronavirus-enhanced susceptibility to bacterial infections. Our data show that coronavirus infection impairs the host ability to clear invading bacterial pathogens and potentiates lung tissue damage in mice. Mechanistically, coronavirus limits the bacterial killing ability of macrophages by impairing lysosomal acidification and fusion with engulfed bacteria. In addition, coronavirus-induced lysosomal dysfunction promotes pyroptotic cell death and the release of IL-1β. Inhibition of cathepsin B decreased cell death and IL-1β release and promoted bacterial clearance in mice with postcoronavirus bacterial infection.

Abstract PO012: Cigarette smoke downregulates mature microRNA-1 in non-small cell cancer (NSCLC) tumor microenvironment

Rationale: We and others had shown that microRNA-1 (miR-1) is downregulated in the non-small cell lung cancer (NSCLC) tumor microenvironment and that a low mature miR-1 level in the tumor is a predictor of shorter overall survival in lung adenocarcinoma patients. Molecular alterations within the tumor microenvironment can induce cancerization and CS is the most prevalent inducer of NSCLC. In this study we evaluated the clinical associations of miR-1 in clinical samples and its significance as an indicator of cancerization. Methods: We assessed the clinical associations of miR-1 in the tumor (T), adjacent cancer-free (AT), and distant cancer-free (DT) lung tissues of 82 NSCLC patients which were obtained by bronchoscopy and surgery. Ex-vivo cultures of normal human lung tissues and cultured human bronchial epithelial cells, immortalized human endothelial cell were exposed to increasing percentage of CS extract in the growth media and harvested after 24 hours. Mature miR-1 levels and mRNA were measured by Taqman assay and quantitative real time PCR, respectively. Human lung epithelial and endothelial fractions were isolated by Magnetic-activated cell sorting (MACS) technique. For clinical data analysis we used SAS 9.4 proc correction for spearman rank test, proc logistic for regression model analysis and Kaplan-Meier analysis for survival studies. Results: In NSCLC patients, mature miR-1 levels in the tumor had an inverse correlation with the extent of CS exposure (pack-year of smoking). Also, miR-1 levels in AT and DT samples of current smokers were significantly lower than the former smokers, suggesting that CS has a suppressive effect on miR-1 levels. We asked whether CS exposure decreases mature miR-1 levels in the lung tissue. Treatment of ex vivo human lung sample with CS specifically decreased mature miR-1 levels without altering its precursors. This change was observed in both epithelial and endothelial cells isolated from the ex-vivo lungs, as well as cultured cells. Next, we asked whether miR-1 changes in the lungs of NSCLC patients has clinical significance. We found that miR-1 levels in the tumor, AT and DT tissues follows a cancerization gradient. MiR-1 levels were lowest and showed the least variability in the tumors and became higher and more widely distributed in the AT and DT samples. Moreover, mature miR-1 levels in the AT samples had a significant association with overall survival of the patient. Conclusion:Our observations show that CS specifically downregulates mature miR-1 in the NSCLC microenvironment, and together with our previous findings strongly suggests that miR-1 downregulation is an inducer of cancerization.

Citation Format: Asawari Korde, Anuradha Ramaswamy, Mark S. Godfrey, Margaret A. Pisani, Jonathan T. Puchalski, Shervin S. Takyar. Cigarette smoke downregulates mature microRNA-1 in non-small cell cancer (NSCLC) tumor microenvironment [abstract]. In: Proceedings of the AACR Virtual Special Conference on the Evolving Tumor Microenvironment in Cancer Progression: Mechanisms and Emerging Therapeutic Opportunities; in association with the Tumor Microenvironment (TME) Working Group; 2021 Jan 11-12. Philadelphia (PA): AACR; Cancer Res 2021;81(5 Suppl):Abstract nr PO012.

An endothelial microRNA-1-regulated network controls eosinophil trafficking in asthma and chronic rhinosinusitis

BACKGROUND

Airway eosinophilia is a prominent feature of asthma and chronic rhinosinusitis (CRS), and the endothelium plays a key role in eosinophil trafficking. To date, microRNA-1 (miR-1) is the only microRNA known to be regulated in the lung endothelium in asthma models.

OBJECTIVE

We sought to determine the role of endothelial miR-1 in allergic airway inflammation.

METHODS

We measured microRNA and mRNA expression using quantitative RT-PCR. We used ovalbumin and house dust mite models of asthma. Endothelium-specific overexpression of miR-1 was achieved through lentiviral vector delivery or induction of a transgene. Tissue eosinophilia was quantified by using Congo red and anti-eosinophil peroxidase staining. We measured eosinophil binding with a Sykes-Moore adhesion chamber. Target recruitment to RNA-induced silencing complex was assessed by using anti-Argonaute2 RNA immunoprecipitation. Surface P-selectin levels were measured by using flow cytometry.

RESULTS

Serum miR-1 levels had inverse correlations with sputum eosinophilia, airway obstruction, and number of hospitalizations in asthmatic patients and sinonasal tissue eosinophilia in patients with CRS. IL-13 stimulation decreased miR-1 levels in human lung endothelium. Endothelium-specific overexpression of miR-1 reduced airway eosinophilia and asthma phenotypes in murine models and inhibited IL-13-induced eosinophil binding to endothelial cells. miR-1 recruited P-selectin, thymic stromal lymphopoietin, eotaxin-3, and thrombopoietin receptor to the RNA-induced silencing complex; downregulated these genes in the lung endothelium; and reduced surface P-selectin levels in IL-13-stimulated endothelial cells. In our asthma and CRS cohorts, miR-1 levels correlated inversely with its target genes.

CONCLUSION

Endothelial miR-1 regulates eosinophil trafficking in the setting of allergic airway inflammation. miR-1 has therapeutic potential in asthmatic patients and patients with CRS.

Lung Endothelial MicroRNA-1 Regulates Tumor Growth and Angiogenesis

RATIONALE

Vascular endothelial growth factor down-regulates microRNA-1 (miR-1) in the lung endothelium, and endothelial cells play a critical role in tumor progression and angiogenesis.

OBJECTIVES

To examine the clinical significance of miR-1 in non-small cell lung cancer (NSCLC) and its specific role in tumor endothelium.

METHODS

miR-1 levels were measured by Taqman assay. Endothelial cells were isolated by magnetic sorting. We used vascular endothelial cadherin promoter to create a vascular-specific miR-1 lentiviral vector and an inducible transgenic mouse. KRAS^{G12D mut}/Trp^53-/- (KP) mice, lung-specific vascular endothelial growth factor transgenic mice, Lewis lung carcinoma xenografts, and primary endothelial cells were used to test the effects of miR-1.

MEASUREMENTS AND MAIN RESULTS

In two cohorts of patients with NSCLC, miR-1 levels were lower in tumors than the cancer-free tissue. Tumor miR-1 levels correlated with the overall survival of patients with NSCLC. miR-1 levels were also lower in endothelial cells isolated from NSCLC tumors and tumor-bearing lungs of KP mouse model. We examined the significance of lower miR-1 levels by testing the effects of vascular-specific miR-1 overexpression. Vector-mediated delivery or transgenic overexpression of miR-1 in endothelial cells decreased tumor burden in KP mice, reduced the growth and vascularity of Lewis lung carcinoma xenografts, and decreased tracheal angiogenesis in vascular endothelial growth factor transgenic mice. In endothelial cells, miR-1 level was regulated through phosphoinositide 3-kinase and specifically controlled proliferation, de novo DNA synthesis, and ERK1/2 activation. Myeloproliferative leukemia oncogene was targeted by miR-1 in the lung endothelium and regulated tumor growth and angiogenesis.

CONCLUSIONS

Endothelial miR-1 is down-regulated in NSCLC tumors and controls tumor progression and angiogenesis.

Tissue inhibitor of metalloproteinase-1 modulates allergic lung inflammation in murine asthma

Matrix metalloproteinases (MMPs) modulate development, inflammation, and repair in lungs. Tissue inhibitors of MMPs (TIMPs) interact with MMPs, controlling the intensity and nature of the response to injury. Absence of MMP-9, -2, and -8 activities is associated with altered lung inflammation during allergic sensitization. To test the hypothesis that the absence of TIMP-1 enhances allergic lung inflammation, airway hyperreactivity (AHR), and lung remodeling in asthma, we studied TIMP-1 null (TIMP-1 KO) mice and their WT controls using an ovalbumin (OVA) asthma model. TIMP-1 KO mice, compared to WT controls, developed an asthma phenotype characterized by AHR, pronounced cellular lung infiltrates, greater reduction in lung compliance, enhanced Th2 cytokine mRNA and protein expression, and altered collagen lung content associated with enhanced MMP-9 activity. Our findings support the hypothesis that TIMP-1 plays a protective role by preventing AHR and modulating inflammation, remodeling, and cytokine expression in an animal model of asthma.

Vitamin B12 and hepatitis C: molecular biology and human pathology

Cobalamins are stored in high concentrations in the human liver and thus are available to participate in the regulation of hepatotropic virus functions. We show that cyanocobalamin (vitamin B12) inhibited the HCV internal ribosome entry site (IRES)-dependent translation of a reporter gene in vitro in a dose-dependent manner without significantly affecting the cap-dependent mechanism. Vitamin B12 failed to inhibit translation by IRES elements from encephalomyocarditis virus (EMCV) or classical swine fever virus (CSFV). We also demonstrate a relationship between the total cobalamin concentration in human sera and HCV viral load (a measure of viral replication in the host). The mean viral load was two orders of magnitude greater when the serum cobalamin concentration was above 200 pM (P < 0.003), suggesting that the total cobalamin concentration in an HCV-infected liver is biologically significant in HCV replication.