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H&E images of a plexiform lesion (PL) in the lung of a 2-day-old layer chicken, captured in the same section at 200 × (2A, upper panel) and 400 × (2B, lower panel) magnifications. 2A: This lesion apparently arises from the adjacent interparabronchial arteriole (ar) coursing between 3 adjacent parabronchi. 2B: The lesion contains several foam-like macrophages (MΦ) and slit-like channels (c) lined by endothelial cells.
Source publication
Plexiform lesions are characteristic histological changes of pulmonary arteries in human patients with severe pulmonary arterial hypertension (PAH) and are regarded as angiogenic lesions. Meat-type broiler chickens are susceptible to PAH and can develop plexiform lesions spontaneously. Whether the lesion development in broilers is associated with P...
Citations
... In addition, our group have recently identified CD133+/VEGFR-2+ EPCs in the lesions and proposed a concept that the formation of plexiform lesions is associated with the phenotypical change of EPCs to macrophages [30,31]. Furthermore, studies have shown that the incidence and density of plexiform-like lesions in broilers tend to increase with elevated pulmonary pressure [22,32]. Unexpectedly, our previous studies have shown that the development of plexiform lesions in post-hatch broilers is not associated with any of the major angiogenic pathways [32]. ...
... Furthermore, studies have shown that the incidence and density of plexiform-like lesions in broilers tend to increase with elevated pulmonary pressure [22,32]. Unexpectedly, our previous studies have shown that the development of plexiform lesions in post-hatch broilers is not associated with any of the major angiogenic pathways [32]. ...
... Indeed, several studies, including our own, have documented the presence of plexiform lesions in newly hatched broilers [29,32], suggesting that these lesions may originate during embryonic development and persist post-hatch. This may provide an explanation for the absence of an association between angiogenic factors and plexiform lesion development in post-hatch birds. ...
Plexiform lesions are a hallmark of pulmonary arterial hypertension (PAH) in humans and are proposed to stem from dysfunctional angioblasts. Broiler chickens (Gallus gallus) are highly susceptible to PAH, with plexiform-like lesions observed in newly hatched individuals. Here, we reported the emergence of plexiform-like lesions in the embryonic lungs of broiler chickens. Lung samples were collected from broiler chickens at embryonic day 20 (E20), hatch, and one-day-old, with PAH-resistant layer chickens as controls. Plexiform lesions consisting of CD133+/vascular endothelial growth factor receptor type-2 (VEGFR-2)+ angioblasts were exclusively observed in broiler embryos and sporadically in layer embryos. Distinct gene profiles of angiogenic factors were observed between the two strains, with impaired VEGF-A/VEGFR-2 signaling correlating with lesion development and reduced arteriogenesis. Pharmaceutical inhibition of VEGFR-2 resulted in enhanced lesion development in layer embryos. Moreover, broiler embryonic lungs displayed increased activation of HIF-1α and nuclear factor erythroid 2-related factor 2 (Nrf2), indicating a hypoxic state. Remarkably, we found a negative correlation between lung Nrf2 activation and VEGF-A and VEGFR-2 expression. In vitro studies indicated that Nrf2 overactivation restricted VEGF signaling in endothelial progenitor cells. The findings from broiler embryos suggest an association between plexiform lesion development and impaired VEGF system due to aberrant activation of Nrf2.
... Domesticated fast growing meat-type chickens (broiler chickens) are highly prone to idiopathic PAH (previously known as ascites syndrome; pulmonary hypertension syndrome) [35][36][37], and can spontaneously develop plexiform lesions in small pulmonary arteries exhibiting histological features similar to that seen in human PAH [38][39][40]. We have recently confirmed the presence of eEPCs (CD133+/VEGFR-2+ cells) and foam-like macrophages in the structures, and provided evidence that the lesion development in this avian model is associated with hemodynamic stress [41,42]. More recently, we showed that transplantation of mesenchymal stromal cells attenuates neointimal and plexogenic arteriopathy in PAH broiler chickens through modulating lung inflammation [43]. ...
... Despite that fact that PAH broilers demonstrate increased plexiform lesions in their lungs [60], we and others have shown that PAH is not an essential prerequisite of the structures [38,39,42]. Nevertheless, an elevation in pulmonary arterial pressure appears to play a role in the process [41]. It is now believed that increases in pulmonary arterial pressure may create turbulent flow in increasing numbers of branch points or curved portions, leading to increased plexiform lesions as observed in PAH broilers [60]. ...
Background
Plexiform lesions, which have a dynamic appearance in structure and cellular composition, are the histological hallmark of severe pulmonary arterial hypertension in humans. The pathogenesis of the lesion development remains largely unknown, although it may be related to local inflammation and dysfunction in early progenitor endothelial cells (eEPCs). We tested the hypothesis that eEPCs contribute to the development of plexiform lesions by differentiating into macrophages in the setting of chronic inflammation.
Methods
The eEPC markers CD133 and VEGFR-2, macrophage lineage marker mannose receptor C-type 1 (MRC1), TNFα and nuclear factor erythroid 2-related factor 2 (Nrf2) in plexiform lesions in a broiler model were determined by immunohistochemistry. eEPCs derived from peripheral blood mononuclear cells were exposed to TNFα, and macrophage differentiation and angiogenic capacity of the cells were evaluated by phagocytotic and Matrigel plug assays, respectively. The role of Nrf2 in eEPC-to-macrophage transition as well as in MRC1 expression was also evaluated. Intratracheal installation of TNFα was conducted to determine the effect of local inflammation on the formation of plexiform lesions.
Results
Cells composed of the early lesions have a typical eEPC phenotype whereas those in more mature lesions display molecular and morphological characteristics of macrophages. Increased TNFα production in plexiform lesions was observed with lesion progression. In vitro studies showed that chronic TNFα challenge directed eEPCs to macrophage differentiation accompanied by hyperactivation of Nrf2, a stress-responsive transcription factor. Nrf2 activation (Keap1 knockdown) caused a marked downregulation in CD133 but upregulation in MRC1 mRNA. Dual luciferase reporter assay demonstrated that Nrf2 binds to the promoter of MRC1 to trigger its expression. In good agreement with the in vitro observation, TNFα exposure induced macrophage differentiation of eEPCs in Matrigel plugs, resulting in reduced neovascularization of the plugs. Intratracheal installation of TNFα resulted in a significant increase in plexiform lesion density.
Conclusions
This work provides evidence suggesting that macrophage differentiation of eEPCs resulting from chronic inflammatory stimulation contributes to the development of plexiform lesions. Given the key role of Nrf2 in the phenotypic switching of eEPCs to macrophages, targeting this molecular might be beneficial for intervention of plexiform lesions.
... [18][19][20][21][22][23] We have recently proposed a concept that the formation of plexiform lesions is associated with local immune/inflammatory response resulting from hemodynamic stress. 21,24 It is now well established that, like that in humans, pulmonary artery endothelial cell damage plays a major role in the pathogenesis of PAH in broilers. [25][26][27] Thus, broilers offer a particularly useful model for the study of PAH pathogenesis and development of new therapies for PAH. ...
... Plexiform lesions in each slide were also counted and lesion density (number of lesions per section/cm 2 per section) was calculated as described previously. 24,33 Real-Time Quantitative PCR (qPCR) Total RNA was extracted from frozen lung tissue by using RNA-Quick Purification Kit according to the manufacturer's instructions (Yishan, Shanghai, China). First-strand cDNA was synthesized from 1000 ng total RNA using HiScript II Q RT SuperMix for qPCR with genomic DNA wiper (Vazyme, Nanjing, China). ...
... The primer sets used and the amplification program have been described previously. 24 The relative expression of the target genes was corrected to reference genes B2M and RPL19 using efficiency corrected method (Pfaffl). ...
Purpose
Pulmonary arterial hypertension (PAH) is a progressive and fatal pulmonary vascular disease initiated by endothelial dysfunction. Mesenchymal stromal cells (MSCs) have been shown to ameliorate PAH in various rodent models; however, these models do not recapitulate all the histopathological alterations observed in human PAH. Broiler chickens (Gallus gallus) can develop PAH spontaneously with neointimal and plexogenic arteriopathy strikingly similar to that in human patients. Herein, we examined the protective effects of MSC transplantation on the development of PAH in this avian model.
Methods
Mixed-sex broilers at 15 d of age were received 2×10⁶ MSCs or PBS intravenously. One day later, birds were exposed to cool temperature with excessive salt in their drinking water to induce PAH. Cumulative morbidity from PAH and right-to-left ventricle ratio were recorded. Lung histologic features were evaluated for the presence of endothelial damage, endothelial proliferation and plexiform lesions. Expression of proinflammatory mediators and angiogenic factors in the lung was detected. Matrigel tube formation assay was performed to determine the angiogenic potential of endogenous MSCs.
Results
MSC administration reduced cumulative PAH morbidity and attenuated endothelial damage, plexiform lesions and production of inflammatory mediators in the lungs. No significant difference in the expression of paracrine angiogenic factors including VEGF-A and TGF-β was determined between groups, suggesting that they are not essential for the beneficial effect of MSC transplantation. Interestingly, the endogenous MSCs from birds receiving MSC transplantation demonstrated endothelial differentiatial capacity in vitro whereas those from the mock birds did not.
Conclusion
Our results support the therapeutic use of MSC transplantation for PAH treatment and suggest that exogenous MSCs produce beneficial effects through modulating inflammation and endogenous MSC-mediated vascular repair.
... Several studies suggest that chronic hypoxia or areas of high altitudes result in pulmonary hypertension (Riley and Sciurba, 2019;Zhang et al., 2018). Pulmonary arterial remodeling is a pathological characteristic of pulmonary hypertension (Tan et al., 2018). Vascular remodeling is mainly manifested by abnormal proliferation of the inner, middle ...
Ascites syndrome (AS) is a common nutritional metabolic disease in broilers that results in major loss to the breeding industry. The occurrence of AS is closely related to the abnormal proliferation of pulmonary artery smooth muscles cells (PASMCs) caused by hypoxia. The transient receptor potential cation channel subfamily C member 6 (TRPC6) is a Ca 2+ channel situated on cell membranes, and belongs to the proliferation of PASMCs caused by hypoxia in mammals. However, its role in hypoxic PASMCs in broilers remains unclear. Here, we investigated the effects of TRPC6 on the proliferation and apoptosis of primary chicken PASMCs under hypoxic conditions using an in vitro model. Primary chicken PASMCs were cultured under normoxic or hypoxic conditions (3% O2). The hypoxic cells were treated with 10 μM of SKF 96365 or 50 μM of fluofenamic acid (FFA) to inhibit or activate TRPC6, respectively. Cell viability was detected by CCK-8, intracellular Ca 2+ levels, cell cycle and cell apoptosis were assayed by a flow cytometric assay, the mRNA levels of TRPC6 were measured by digital-droplet PCR (ddPCR), the protein levels of TRPC6 were tested by immunoblotting, and the mRNA levels of caspase3 were detected by RT-PCR. Our results revealed that exposing PASMCs to hypoxic conditions for 48h increased cell viability and intracellular Ca 2+ levels. Additionally, hypoxic conditions increased the expression of TRPC6 and promoted cell cycle progression, but decreased cell apoptosis and caspase 3 mRNA levels. When the hypoxic PASMCs were treated with SKF 96365, inhibition of TRPC6 and cell proliferation and promotion of apoptosis were observed only in the first 24h of treatment. Treatment with FFA for 24h had the opposite effects. These results suggested that TRPC6-mediated Ca 2+ entry contributed to hypoxia-induced PASMCs proliferation and apoptosis resistance, which identified TRPC6 as a possible key target in vascular remodeling in chicken.
... PASMCs increase CXCL8 expression in response to mechanical stress (Costa et al., 2018). Broiler chickens, which develop spontaneous PAH with plexiform-like lesions, display decreased expression of CXCL8 compared to layer chickens which are resistant to PAH (Tan, Shao, Fan, & Ying, 2018). Consistent with a link to inflammation, NF-κB induces CXCL8 expression in PAECs via specifically binding to its promoter (Mumby et al., 2017). ...
Pulmonary arterial hypertension (PAH) is characterized by progressive pulmonary artery remodelling leading to increased right ventricular pressure overload, which results in right heart failure and premature death. Inflammation plays a central role in the development of PAH, and the recruitment and function of immune cells are tightly regulated by chemotactic cytokines called chemokines. A number of studies have shown that the development and progression of PAH are associated with the dysregulated expression of several chemokines and chemokine receptors in the pulmonary vasculature. Moreover, some chemokines are differentially regulated in the pressure‐overloaded right ventricle. Recent studies have tested the efficacy of pharmacological agents targeting several chemokines and chemokine receptors for their effects on the development of PAH, suggesting that these receptors could serve as useful therapeutic targets. In this review, we provide recent insights into the role of chemokines and chemokine receptors in PAH and RV remodelling and the opportunities and roadblocks in targeting them.
LINKED ARTICLES
This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.1/issuetoc
Ascites syndrome in broilers (AS), also known as broiler pulmonary hypertension syndrome (PHS), is a common nutritional and metabolic disease in commercial broilers. It is a disease characterised by a progressive increase in pulmonary artery pressure, followed by right ventricular hypertrophy, right heart failure and ultimately death. Diseased chickens with AS have characteristic lesions including right heart hypertrophy, ascites, pulmonary congestion and pulmonary oedema can be observed after opening the thoracic cavity. Pulmonary arterial hypertension (PAH) is a key link in the development of AS in broilers. Pulmonary artery vasoconstriction and pulmonary artery remodelling promote the development of AS. The AS is commonly influenced by a variety of mechanisms including hypoxia, endothelial dependency regulation, vascular active material imbalance, oxidative stress, inflammation, in situ thrombosis and genetic tendency. This review focuses on the regulation of vasoactive substances, oxidative stress, Hypoxia-inducible factors, immunomodulation and non-epigenetic phenomena on AS. The aim of this study is to review the current understanding of the pathogenesis of AS and to provide insights into the future development of this growing field for the control of AS in broiler chickens.
Pulmonary arterial hypertension (PAH) is the major cause of death in fast growing meat-type chickens (broiler chickens). At present, the underlying mechanisms that give rise to PAH are not fully understood. In order to identify the metabonomics profiles characterizing the process, we conducted a comprehensive gas chromatography-mass spectrometry (GC-MS)-based metabolic profiling of lung tissues from PAH broilers and age-matched controls. PAH was induced by excess salt in drinking water. Medial hypertrophy of pulmonary arteries was present in PAH birds as compared with controls. The metabonomics profiles of lung tissues well distinguished PAH broilers from control subjects. Significant changes in the levels of 41 metabolites were detected in PAH vs. normal birds. Aside from the metabolic alterations indicating a status of oxidative stress and inflammation, evidence of reduced cellular uptake of arginine due to increased lysine biosynthesis and of a shift of arginine metabolism to arginase pathway were observed. In addition, PAH birds showed increased biosynthesis of fatty acids, which may be associated with excessive proliferation of vascular cells during pulmonary vascular remodeling. Furthermore, we observed significant changes in pentose phosphate pathway (PPP) and increased aminomalonic acid in PAH broilers. These results provide additional biochemical insights into the pathogenesis of the PAH. Our data may lead to the development of new strategies to control PAH in broilers.
