Human iPSC-Based Model of COPD to Investigate Disease Mechanisms, Predict SARS-COV-2 Outcome, and Test Preventive Immunotherapy.

Chronic inflammation and dysregulated repair mechanisms after epithelial damage have been implicated in chronic obstructive pulmonary disease (COPD). However, the lack of ex vivo-models that accurately reflect multicellular lung tissue hinders our understanding of epithelial-mesenchymal interactions in COPD. Through a combination of transcriptomic and proteomic approaches applied to a sophisticated in vitro iPSC-alveolosphere with fibroblasts model, epithelial-mesenchymal crosstalk was explored in COPD and following SARS-CoV-2 infection.

Functional Impact of Human Genetic Variants of /Endostatin on Pulmonary Endothelium.

Pulmonary arterial hypertension (PAH) is an incurable disease characterized by disordered and dysfunctional angiogenesis leading to small-vessel loss and an obliterative vasculopathy. The pathogenesis of PAH is not fully understood, but multiple studies have demonstrated links between elevated angiostatic factors, disease severity, and adverse clinical outcomes. ES (endostatin), one such circulating angiostatic peptide, is the cleavage product of the proteoglycan (collagen α1[XVIII] chain).

CD11b interstitial macrophages are required for ischemia-induced lung angiogenesis.

The importance of myeloid cells in promoting neovascularization has been shown in a number of pathological settings in several organs. However, the specific role of macrophages in promoting systemic angiogenesis during pulmonary ischemia is not fully determined. Our past work suggested that cells of monocytic lineage contributed to systemic angiogenesis in the lung since clodronate-induced depletion of all macrophages resulted in attenuated neovascularization.

Anti-angiogenic Nanotherapy Inhibits Airway Remodeling and Hyper-responsiveness of Dust Mite Triggered Asthma in the Brown Norway Rat.

Although angiogenesis is a hallmark feature of asthmatic inflammatory responses, therapeutic anti-angiogenesis interventions have received little attention. Assess the effectiveness of anti-angiogenic Sn2 lipase-labile prodrugs delivered via αβ-micellar nanotherapy to suppress microvascular expansion, bronchial remodeling, and airway hyper-responsiveness in Brown Norway rats exposed to serial house dust mite (HDM) inhalation challenges. Anti-neovascular effectiveness of αβ-mixed micelles incorporating docetaxel-prodrug (Dxtl-PD) or fumagillin-prodrug (Fum-PD) were shown to robustly suppress neovascular expansion (p<0.

Lymphangiogenesis in rat asthma model.

Although bronchial angiogenesis has been well documented in allergic asthma, lymphangiogenesis has not been widely studied. Therefore, we evaluated changes in lung lymphatics in a rat model of allergen-induced asthma using house dust mite (Der p 1; 100 μg/challenge). Additionally, properties of isolated lung lymphatic endothelial cells (CD45, CD141, LYVE-1, Prox-1) were studied in vitro.

Bronchial Artery Angiogenesis Drives Lung Tumor Growth.

Angiogenesis is vital for tumor growth but in well-vascularized organs such as the lung its importance is unclear. This situation is complicated by the fact that the lung has two separate circulations, the pulmonary and the systemic bronchial circulation. There are few relevant animal models of non-small cell lung cancer, which can be used to study the lung's complex circulations, and mice, lacking a systemic bronchial circulation cannot be used.

Effector T Cells and Ischemia-Induced Systemic Angiogenesis in the Lung.

Lymphocytes have been shown to modulate angiogenesis. Our previous work showed that T regulatory (Treg) cell depletion prevented angiogenesis. In the present study, we sought to examine T-cell populations during lung angiogenesis and subsequent angiostasis.

Lung Angiogenesis Requires CD4(+) Forkhead Homeobox Protein-3(+) Regulatory T Cells.

Angiogenesis in ischemic organs is modulated by immune cells. Systemic neovascularization of the ischemic lung requires macrophages, with chemokines playing a central role in new vessel growth. Because regulatory T (Treg) cells modulate tumor-induced neovascularization, we questioned whether this CD4(+) lymphocyte subset impacts blood vessel growth during ischemia.

Nitric oxide synthase promotes distension-induced tracheal venular leukocyte adherence.

The process of leukocyte recruitment to the airways in real time has not been extensively studied, yet airway inflammation persists as a major contributor to lung pathology. We showed previously in vivo, that neutrophils are recruited acutely to the large airways after periods of airway distension imposed by the application of positive end-expiratory pressure (PEEP). Given extensive literature implicating products of nitric oxide synthase (NOS) in lung injury after ventilatory over-distension, we questioned whether similar mechanisms exist in airway post-capillary venules.

Angiogenesis and airway reactivity in asthmatic Brown Norway rats.

Expanded and aberrant bronchial vascularity, a prominent feature of the chronic asthmatic airway, might explain persistent airway wall edema and sustained leukocyte recruitment. Since it is well established that there are causal relationships between exposure to house dust mite (HDM) and the development of asthma, determining the effects of HDM in rats, mammals with a bronchial vasculature similar to humans, provides an opportunity to study the effects of bronchial angiogenesis on airway function directly. We studied rats exposed bi-weekly to HDM (Der p 1; 50 μg/challenge by intranasal aspiration, 1, 2, 3 weeks) and measured the time course of appearance of increased blood vessels within the airway wall.

Loss of cystic fibrosis transmembrane conductance regulator impairs lung endothelial cell barrier function and increases susceptibility to microvascular damage from cigarette smoke.

Abnormal lung microvascular endothelial vascular barrier function may contribute to pulmonary inflammation, such as that occurring during inhalation of cigarette smoke (CS). Cystic fibrosis transmembrane conductance regulator (CFTR), an anion channel expressed in both epithelial and endothelial cells, regulates the organization of tight junctions between epithelial cells and has also been implicated in the transport of sphingosine-1 phosphate (S1P), a vascular barrier-enhancing sphingolipid. Because CS has been shown to affect CFTR function, we hypothesized that CFTR function contributes to lung endothelial cell barrier and that CFTR dysfunction worsens CS-induced injury.

Chemokine localization in bronchial angiogenesis.

Angiogenesis in the lung involves the systemic bronchial vasculature and becomes prominent when chronic inflammation prevails. Mechanisms for neovascularization following pulmonary ischemia include growth factor transit from ischemic parenchyma to upstream bronchial arteries, inflammatory cell migration/recruitment through the perfusing artery, and paracrine effects of lung cells within the left bronchus, the niche where arteriogenesis takes place. We analyzed left lung bronchoalveolar lavage (BAL) fluid and left bronchus homogenates after left pulmonary artery ligation (LPAL) in rats, immediately after the onset of ischemia (0 h), 6 h and 24 h later.

Strain variation in response to lung ischemia: role of MMP-12.

Background: Systemic neovascularization of the lung during chronic ischemia has been observed in all mammals studied. However, the proteins that orchestrate the complex interaction of new vessel growth and tunneling through lung tissue matrix have not been described. Although previous work has demonstrated the CXC chemokines are essential growth factors in the process of angiogenesis in mice and rats, key matrix proteins have not been identified.

Effects of ischemia on lung macrophages.

Angiogenesis after pulmonary ischemia is initiated by reactive O(2) species and is dependent on CXC chemokine growth factors, and its magnitude is correlated with the number of lavaged macrophages. After complete obstruction of the left pulmonary artery in mice, the left lung is isolated from the peripheral circulation until 5-7 days later, when a new systemic vasculature invades the lung parenchyma. Consequently, this model offers a unique opportunity to study the differentiation and/or proliferation of monocyte-derived cells within the lung.

Increased hyaluronan fragmentation during pulmonary ischemia.

Hyaluronan (HA), a glycosaminoglycan critical to the lung extracellular matrix, has been shown to dissociate into low-molecular-weight (LMW) HA fragments following exposure to injurious stimuli. In the present study we questioned whether lung HA changed during ischemia and whether changes had an effect on subsequent angiogenesis. After left pulmonary artery ligation (LPAL) in mice, we analyzed left lung homogenates immediately after the onset of ischemia (0 h) and intermittently for 14 days.

Role of ROS in ischemia-induced lung angiogenesis.

Pulmonary artery obstruction and subsequent lung ischemia have been shown to induce systemic angiogenesis despite preservation of normoxia. The underlying mechanisms, however, remain poorly understood. In a mouse model of lung ischemia induced by left pulmonary artery ligation (LPAL), we showed previously, the formation of a new systemic vasculature to the ischemic lung.

cGMP increases antioxidant function and attenuates oxidant cell death in mouse lung microvascular endothelial cells by a protein kinase G-dependent mechanism.

Increasing evidence suggests that endothelial cytotoxicity from reactive oxygen species (ROS) contributes to the pathogenesis of acute lung injury. Treatments designed to increase intracellular cGMP attenuate ROS-mediated apoptosis and necrosis in several cell types, but the mechanisms are not understood, and the effect of cGMP on pulmonary endothelial cell death remains controversial. In the current study, increasing intracellular cGMP by either 8pCPT-cGMP (50 microM) or atrial natriuretic peptide (10 nM) significantly attenuated cell death in H(2)O(2)-challenged mouse lung microvascular (MLMVEC) monolayers.

Differential activity of pro-angiogenic CXC chemokines.

We showed previously in a mouse model of lung ischemia-induced angiogenesis, enhanced expression of the three ELR+ CXC chemokines (KC, LIX, and MIP-2) and that blockade of the ligand receptor CXCR(2) limited neovascularization. The present study was undertaken to determine the relative abundance and angiogenic potential of the three CXC chemokines and whether RhoA activation explained the measured differences in potencies. We found that LIX showed the greatest absolute amount in the in vivo model 4 h after left pulmonary artery obstruction (LIX>KC>MIP-2; p<0.

Soluble guanylyl cyclase contributes to ventilator-induced lung injury in mice.

High tidal volume (HV(T)) ventilation causes pulmonary endothelial barrier dysfunction. HV(T) ventilation also increases lung nitric oxide (NO) and cGMP. NO contributes to HV(T) lung injury, but the role of cGMP is unknown.

Effects of distension on airway inflammation and venular P-selectin expression.

We previously have shown in mice and rats, enhanced leukocyte recruitment to airway postcapillary venules after excessive distention imposed by the application of positive end-expiratory pressure. Because P-selectin was shown to be essential for this outcome, we sought to establish an in vitro endothelial cell model and determine the mechanisms whereby mechanical distension alters adhesion molecule expression. P-selectin surface expression on mouse jugular vein endothelial cells exposed to cyclic stretch (5 or 20% elongation for 5 min; Flexercell) were compared with static cells.

Inflammation and ischemia-induced lung angiogenesis.

A role for inflammation in modulating the extent of angiogenesis has been shown for a number of organs. The present study was undertaken to evaluate the importance of leukocyte subpopulations for systemic angiogenesis of the lung after left pulmonary artery ligation (LPAL) in a mouse model of chronic pulmonary thromboembolism. Since we (24) previously showed that depletion of neutrophils did not alter the angiogenic outcome, we focused on the effects of dexamethasone pretreatment (general anti-inflammatory) and gadolinium chloride treatment (macrophage inactivator) and studied Rag-1(-/-) mice (T/B lymphocyte deficient).

MIP-2 causes differential activation of RhoA in mouse aortic versus pulmonary artery endothelial cells.

Previously, we have shown that endothelial cell chemotaxis to the proangiogenic chemokine MIP-2 (macrophage inflammatory protein-2) is much greater in mouse aortic endothelial cells (EC) than pulmonary arterial endothelial cells (PA EC). This was true despite the observation that both cell types display comparable levels of the ligand receptor, CXCR(2) (8). Since the systemic arterial circulation is proangiogenic in the adult lung and the pulmonary circulation is relatively resistant to neovascularization, we questioned whether the observed functional heterogeneity is related to inherent differences in cell signaling cascades of the two EC subtypes.

Role of protein kinase G in barrier-protective effects of cGMP in human pulmonary artery endothelial cells.

Increases in endothelial cGMP prevent oxidant-mediated endothelial barrier dysfunction, but the downstream mechanisms remain unclear. To determine the role of cGMP-dependent protein kinase (PKG)(I), human pulmonary artery endothelial cells (HPAEC) lacking PKG(I) expression were infected with a recombinant adenovirus encoding PKG(Ibeta) (Ad.PKG) and compared with uninfected and control-infected (Ad.

Difference in proangiogenic potential of systemic and pulmonary endothelium: role of CXCR2.

The systemic vasculature in and surrounding the lung is proangiogenic, whereas the pulmonary vasculature rarely participates in neovascularization. We studied the effects of the proangiogenic ELR+ CXC chemokine MIP-2 (macrophage inflammatory protein-2) on endothelial cell proliferation and chemotaxis. Mouse aortic, pulmonary arterial, and lung microvascular endothelial cells were isolated and subcultured.