Sildenafil limits monocrotaline-induced pulmonary hypertension in rats through suppression of pulmonary vascular remodeling

Jaggeds/Notches promote endothelial-mesenchymal transition-mediated pulmonary arterial hypertension via upregulation of the expression of GATAs

This study tested the hypothesis that Jagged2/Notches promoted the endothelial-mesenchymal transition (endMT)-mediated pulmonary arterial hypertension (PAH) (i.e. induction by monocrotaline [MCT]/63 mg/kg/subcutaneous injection) through increasing the expression of GATA-binding factors which were inhibited by propylthiouracil (PTU) (i.e. 0.1% in water for daily drinking since Day 5 after PAH induction) in rodent. As compared with the control (i.e. HUVECs), the protein expressions of GATAs (3/4/6) and endMT markers (Snail/Zeb1/N-cadherin/vimentin/fibronectin/α-SMA/p-Smad2) were significantly reduced, whereas the endothelial-phenotype markers (CD31/E-cadherin) were significantly increased in silenced JAG2 gene or in silenced GATA3 gene of HUVECs (all p < 0.001). As compared with the control, the protein expressions of intercellular signallings (GATAs [3/4/6], Jagged1/2, notch1/2 and Snail/Zeb1/N-cadherin/vimentin/fibronectin/α-SMA/p-Smad2) were significantly upregulated in TGF-ß/monocrotaline-treated HUVECs that were significantly reversed by PTU treatment (all p < 0.001). By Day 42, the results of animal study demonstrated that the right-ventricular systolic-blood-pressure (RVSBP), RV weight (RVW) and lung injury/fibrotic scores were significantly increased in MCT group than sham-control (SC) that were reversed in MCT + PTU groups, whereas arterial oxygen saturation (%) and vasorelaxation/nitric oxide production of PA exhibited an opposite pattern of RVW among the groups (all p < 0.0001). The protein expressions of hypertrophic (ß-MHC)/pressure-overload (BNP)/oxidative-stress (NOX-1/NOX-2) biomarkers in RV and the protein expressions of intercellular signalling (GATAs3/4/6, Jagged1/2, notch1/2) and endMT markers (Snail/Zeb1/N-cadherin/vimentin/fibronectin/TGF-ß/α-SMA/p-Smad2) in lung parenchyma displayed an identical pattern of RVW among the groups (all p < 0.0001). Jagged-Notch-GATAs signalling, endMT markers and RVSBP that were increased in PAH were suppressed by PTU.

1,8-cineole Ameliorates Right Ventricle Dysfunction Associated With Pulmonary Arterial Hypertension by Restoring Connexin 43 and Mitochondrial Homeostasis

For the first time, the present study unravels a cardiospecific therapeutic approach for Pulmonary Arterial Hypertension (PAH), a disease with a very poor prognosis and high mortality rates due to right ventricle dysfunction. We first established a new in vitro model of high-pressure-induced hypertrophy that closely resembles heart defects associated with PAH and validated our in vitro findings on a preclinical in vivo model of monocrotaline (MCT)-induced PAH. Our results showed the in vitro antihypertrophic effect of 1,8-cineole, a monoterpene widely found in several essential oils. Also, a decrease in RV hypertrophy and fibrosis, and an improvement in heart function in vivo was observed, when 1,8-cineole was applied topically. Furthermore, 1,8-cineole restored gap junction protein connexin43 distribution at the intercalated discs and mitochondrial functionality, suggesting it may act by preserving cardiac cell-to-cell communication and bioenergetics. Overall, our results point out a promising therapeutic compound that can be easily applied topically, thus paving the way for the development of effective cardiac-specific therapies to greatly improve PAH outcomes.

The left ventricle undergoes biomechanical and gene expression changes in response to increased right ventricular pressure overload

Pulmonary hypertension (PH) results in right ventricular (RV) pressure overload and eventual failure. Current research efforts have focused on the RV while overlooking the left ventricle (LV), which is responsible for mechanically assisting the RV during contraction. The objective of this study is to evaluate the biomechanical and gene expression changes occurring in the LV due to RV pressure overload in a mouse model. Nine male mice were divided into two groups: (a) pulmonary arterial banding (PAB, N = 4) and (b) sham surgery (Sham, N = 5). Tagged and steady‐state free precision cardiac MRI was performed on each mouse at 1, 4, and 7 weeks after surgery. At/week7, the mice were euthanized following right/left heart catheterization with RV/LV tissue harvested for histology and gene expression (using RT‐PCR) studies. Compared to Sham mice, the PAB group revealed a significantly decreased LV and RV ejection fraction, and LV maximum torsion and torsion rate, within the first week after banding. In the PAB group, there was also a slight but significant increase in LV perivascular fibrosis, which suggests elevated myocardial stress. LV fibrosis was also accompanied with changes in gene expression in the hypertensive group, which was correlated with LV contractile mechanics. In fact, principal component (PC) analysis of LV gene expression effectively separated Sham and PAB mice along PC2. Changes in LV contractile mechanics were also significantly correlated with unfavorable changes in RV contractile mechanics, but a direct causal relationship was not established. In conclusion, a purely biomechanical insult of RV pressure overload resulted in biomechanical and transcriptional changes in both the RV and LV. Given that the RV relies on the LV for contractile energy assistance, considering the LV could provide prognostic and therapeutic targets for treating RV failure in PH.

Role of Farnesoid X Receptor in the Pathogenesis of Respiratory Diseases

Farnesoid X receptor (FXR) is a bile acid receptor encoded by the Nr1h4 gene. FXR plays an important role in maintaining the stability of the internal environment and the integrity of many organs, including the liver and intestines. The expression of FXR in nondigestible tissues other than in the liver and small intestine is known as the expression of “nonclassical” bile acid target organs, such as blood vessels and lungs. In recent years, several studies have shown that FXR is widely involved in the pathogenesis of various respiratory diseases, such as chronic obstructive pulmonary disease, bronchial asthma, and idiopathic pulmonary fibrosis. Moreover, a number of works have confirmed that FXR can regulate the bile acid metabolism in the body and exert its anti-inflammatory and antifibrotic effects in the airways and lungs. In addition, FXR may be used as a potential therapeutic target for some respiratory diseases. For example, FXR can regulate the tumor microenvironment by regulating the balance of inflammatory and immune responses in the body to promote the occurrence and development of non-small-cell lung cancer (NSCLC), thereby being considered a potential target for immunotherapy of NSCLC. In this article, we provide an overview of the internal relationship between FXR and respiratory diseases to track the progress that has been achieved thus far in this direction and suggest potential therapeutic prospects of FXR in respiratory diseases.

Connexin 43 plays a role in proliferation and migration of pulmonary arterial fibroblasts in response to hypoxia

Pulmonary hypertension (PH) is a disease associated with vasoconstriction and remodelling of the pulmonary vasculature. Pulmonary artery fibroblasts (PAFs) play an important role in hypoxic-induced remodelling. Connexin 43 (Cx43) is involved in cellular communication and regulation of the pulmonary vasculature. Using both in vitro and in vivo models of PH, the aims of this study were to (i) investigate the role of Cx43 in hypoxic-induced proliferation and migration of rat PAFs (rPAFs) and rat pulmonary artery smooth muscle cells (rPASMCs) and (ii) determine whether Cx43 expression is dysregulated in the rat sugen5416/hypoxic model of PH. The role of Cx43 in hypoxic-induced proliferation and migration was investigated using Gap27 (a pharmacological inhibitor of Cx43) or genetic knockdown of Cx43 using siRNA. Cx43 protein expression was increased by hypoxia in rPAFs but not rPASMCs. Hypoxic exposure, in the presence of serum, resulted in an increase in proliferation of rPAFs but not rPASMCs. Hypoxic exposure caused migration of rPAFs but not rPASMCs. Phosphorylation of p38 mitogen-activated protein kinase (MAPK) and ERK1/2 were increased by hypoxia in rPAFs. The effects of hypoxia on proliferation, migration and MAPK phosphorylation in rPAFs were attenuated in the presence of Gap27 or Cx43 siRNA. Cx43 protein expression was increased in sugen5416/hypoxic rat lung; this increased expression was not observed in sugen5416/hypoxic rats treated with the MAPK pathway inhibitor GS-444217. In conclusion, Cx43 is involved in the proliferation and migration of rPAFs in response to hypoxia via the MAPK signalling pathway.

Therapeutic effects of the selective farnesoid X receptor agonist obeticholic acid in a monocrotaline-induced pulmonary hypertension rat model

BACKGROUND

Activation of the farnesoid X receptor (FXR), a member of the nuclear receptor steroid superfamily, leads to anti-inflammatory and anti-fibrotic effects in several tissues, including the lung. We have recently demonstrated a protective effect of the farnesoid X receptor (FXR) agonist obeticholic acid (OCA) in rat models of monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) and bleomycin-induced pulmonary fibrosis. The aim of the present study was to investigate whether the positive effects of OCA treatment could be exerted also in established MCT-induced PAH, i.e., starting treatment 2 weeks after MCT administration.

METHODS

Rats with MCT-induced PAH were treated, 2 weeks after MCT administration, with OCA or tadalafil for two additional weeks. Pulmonary functional tests were performed at week 2 (before treatment) and four (end of treatment). At the same time points, lung morphological features and expression profile of genes related to smooth muscle relaxation/contraction and tissue remodeling were also assessed.

RESULTS

2 weeks after MCT-induced injury, the treadmill resistance (a functional parameter related to pulmonary hypertension) was significantly decreased. At the same time point, we observed right ventricular hypertrophy and vascular remodeling, with upregulation of genes related to inflammation. At week 4, we observed a further worsening of the functional and morphological parameters, accompanied by dysregulation of inflammatory and extracellular matrix markers mRNA expression. Administration of OCA (3 or 10 mg/kg/day), starting 2 weeks after MCT-induced injury, significantly improved pulmonary function, effectively normalizing the exercise capacity. OCA also reverted most of the lung alterations, with a significant reduction of lung vascular wall thickness, right ventricular hypertrophy, and restoration of the local balance between relaxant and contractile pathways. Markers of remodeling pathways were also normalized by OCA treatment. Notably, results with OCA treatment were similar, or even superior, to those obtained with tadalafil, a recently approved treatment for pulmonary hypertension.

CONCLUSIONS

The results of this study demonstrate a significant therapeutic effect of OCA in established MCT-induced PAH, improving exercise capacity associated with reduction of right ventricular hypertrophy and lung vascular remodeling. Thus, OCA dosing in a therapeutic protocol restores the balance between relaxant and contractile pathways in the lung, promoting cardiopulmonary protective actions in MCT-induced PAH.

The Impact of Maternal Fructose Exposure on Angiogenic Activity of Endothelial Progenitor Cells and Blood Flow Recovery After Critical Limb Ischemia in Rat Offspring

Adult metabolic syndrome is considered to be elicited by the developmental programming which is regulated by the prenatal environment. The maternal excess intake of fructose, a wildly used food additive, is found to be associated with developmental programing-associated cardiovascular diseases. To investigate the effect of maternal fructose exposure (MFE) on endothelial function and repair, which participate in the initiation and progress of cardiovascular disease, we applied a rat model with maternal fructose excess intake during gestational and lactational stage and examined the number and function of endothelial progenitor cells (EPCs) in 3-month-old male offspring with induction of critical limb ischemia (CLI). Results showed that the circulating levels of c-Kit+/CD31+ and Sca-1+/KDR+ EPC were reduced by MFE. In vitro angiogenesis analysis indicated the angiogenic activity of bone marrow-derived EPC, including tube formation and cellular migration, was reduced by MFE. Western blots further indicated the phosphorylated levels of ERK1/2, p38-MAPK, and JNK in circulating peripheral blood mononuclear cells were up-regulated by MFE. Fourteen days after CLI, the reduced blood flow recovery, lowered capillary density, and increased fibrotic area in quadriceps were observed in offspring with MFE. Moreover, the aortic endothelium-mediated vasorelaxant response in offspring was impaired by MFE. In conclusion, maternal fructose intake during gestational and lactational stage modulates the number and angiogenic activity of EPCs and results in poor blood flow recovery after ischemic injury.

Hypoxia Exacerbates Inflammatory Acute Lung Injury via the Toll-Like Receptor 4 Signaling Pathway

Acute lung injury (ALI) is characterized by non-cardiogenic diffuse alveolar damage and often leads to a lethal consequence, particularly when hypoxia coexists. The treatment of ALI remains a challenge: pulmonary inflammation and hypoxia both contribute to its onset and progression and no effective prevention approach is available. Here, we aimed to investigate the underlying mechanism of hypoxia interaction with inflammation in ALI and to evaluate hypoxia-inducible factor 1 alpha (HIF-1α)—the crucial modulator in hypoxia—as a potential therapeutic target against ALI. First, we developed a novel ALI rat model induced by a combined low-dose of lipopolysaccharides (LPS) with acute hypoxia. Second, we used gene microarray analysis to evaluate the inflammatory profiles of bronchi alveolar lavage fluid cells of ALI rats. Third, we employed an alveolar macrophage cell line, NR8383 as an in vitro system together with a toll-like receptor 4 (TLR4) antagonist TAK-242, to verify our in vivo findings from ALI animals. Finally, we tested the therapeutic effects of HIF-1α augmentation against inflammation and hypoxia in ALI. We demonstrated that (i) LPS upregulated inflammatory genes, tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6), in the alveolar macrophages of ALI rats, which were further enhanced when ALI combined with hypoxia; (ii) hypoxia exposure could further enhance the upregulation of alveolar macrophageal TLR4 that was noticed in LPS-induced inflammatory ALI, conversely, TLR4 antagonist TAK-242 could suppress the macrophageal expression of TLR4 and inflammatory cytokines, including TNF-α, IL-1β, and IL-6, suggesting that the TLR4 signaling pathway as a central link between inflammation and hypoxia in ALI; (iii) manipulation of HIF-1α in vitro could suppress TLR4 expression induced by combined LPS and hypoxia, via suppressing promoter activity of the TLR4 gene; (iv) preconditioning augmentation of HIF-1α in vivo by HIF hydroxylase inhibitor, DMOG excreted protection against inflammatory, and hypoxic processes in ALI. Together, we see that hypoxia can exacerbate inflammation in ALI via the activation of the TLR4 signaling pathway in alveolar macrophages and predispose impairment of the alveolar-capillary barrier in the development of ALI. Targeting HIF-1α can suppress TLR4 expression and macrophageal inflammation, suggesting the potential therapeutic and preventative value of HIF-1α/TLR4 crosstalk pathway in ALI.

Angiotensin-(1-9) ameliorates pulmonary arterial hypertension via angiotensin type II receptor

Angiotensin-(1-9) [Ang-(1-9)], generated from Ang I by Ang II converting enzyme 2, has been reported to have protective effects on cardiac and vascular remodeling. However, there is no report about the effect of Ang-(1-9) on pulmonary hypertension. The aim of the present study is to investigate whether Ang-(1-9) improves pulmonary vascular remodeling in monocrotaline (MCT)-induced pulmonary hypertensive rats. Sprague-Dawley rats received Ang-(1-9) (576 µg/kg/day) or saline via osmotic mini-pumps for 3 weeks. Three days after implantation of osmotic mini-pumps, 50 mg/kg MCT or vehicle were subcutaneously injected. MCT caused increases in right ventricular weight and systolic pressure, which were reduced by co-administration of Ang-(1-9). Ang-(1-9) also attenuated endothelial damage and medial hypertrophy of pulmonary arterioles as well as pulmonary fibrosis induced by MCT. The protective effects of Ang-(1-9) against pulmonary hypertension were inhibited by Ang type 2 receptor (AT₂R) blocker, but not by Mas receptor blocker. Additionally, the levels of LDH and inflammatory cytokines, such as TNF-α, MCP-1, IL-1β, and IL-6, in plasma were lower in Ang-(1-9) co-treated MCT group than in vehicle-treated MCT group. Changes in expressions of apoptosis-related proteins such as Bax, Bcl-2, Caspase-3 and -9 in the lung tissue of MCT rats were attenuated by the treatment with Ang-(1-9). These results indicate that Ang-(1-9) improves MCT-induced pulmonary hypertension by decreasing apoptosis and inflammatory reaction via AT₂R.

Bone Morphogenetic Protein-Based Therapeutic Approaches

Bone morphogenetic proteins (BMPs) constitute the largest subdivision of the transforming growth factor (TGF)-β family of ligands and exert most of their effects through the canonical effectors Smad1, 5, and 8. Appropriate regulation of BMP signaling is critical for the development and homeostasis of numerous human organ systems. Aberrations in BMP pathways or their regulation are increasingly associated with diverse human pathologies, and there is an urgent and growing need to develop effective approaches to modulate BMP signaling in the clinic. In this review, we provide a wide perspective on diseases and/or conditions associated with dysregulated BMP signal transduction, outline the current strategies available to modulate BMP pathways, highlight emerging second-generation technologies, and postulate prospective avenues for future investigation.

Beneficial effects of bile acid receptor agonists in pulmonary disease models

INTRODUCTION

Bile acids act as steroid hormones, controlling lipid, glucose and energy metabolism, as well as inflammation and fibrosis. Their actions are implemented through activation of nuclear (FXR, VDR, PXR) and membrane G protein-coupled (TGR5, S1PR2) receptors. Areas covered: This review discusses the potential of FXR and TGR5 as therapeutic targets in the treatment of pulmonary disorders linked to metabolism and/or inflammation. Obeticholic acid (OCA) is the most clinically advanced bile acid-derived agonist for FXR-mediated anti-inflammatory and anti-fibrotic effects. It therefore represents an attractive pharmacological approach for the treatment of lung conditions characterized by vascular and endothelial dysfunctions. Expert opinion: Inflammation, vascular remodeling and fibrotic processes characterize the progression of pulmonary arterial hypertension (PAH) and idiopathic pulmonary fibrosis (IPF). These processes are only partially targeted by the available therapeutic options and still represent a relevant medical need. The results hereby summarized demonstrate OCA efficacy in preventing experimental lung disorders, i.e. monocrotaline-induced PAH and bleomycin-induced fibrosis, by abating proinflammatory and vascular remodeling progression. TGR5 is also expressed in the lung, and targeting the TGR5 pathway, using the TGR5 agonist INT-777 or the dual FXR/TGR5 agonist INT-767, could also contribute to the treatment of pulmonary disorders mediated by inflammation and fibrosis.

The role of gap junctions in inflammatory and neoplastic disorders (Review)

Gap junctions are intercellular channels made of connexin proteins, mediating both electrical and biochemical signals between cells. The ability of gap junction proteins to regulate immune responses, cell proliferation, migration, apoptosis and carcinogenesis makes them attractive therapeutic targets for treating inflammatory and neoplastic disorders in different organ systems. Alterations in gap junction profile and expression levels are observed in hyperproliferative skin disorders, lymphatic vessel diseases, inflammatory lung diseases, liver injury and neoplastic disorders. It is now recognized that the therapeutic effects mediated by traditional pharmacological agents are dependent upon gap junction communication and may even act by influencing gap junction expression or function. Novel strategies for modulating the function or expression of connexins, such as the use of synthetic mimetic peptides and siRNA technology are considered.

Adventitial Fibroblast Nox4 Expression and ROS Signaling in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease arising from remodeling and narrowing of pulmonary arteries (PA) resulting in high pulmonary arterial blood pressure and ultimately right ventricular failure. Elevated production of reactive oxygen species (ROS) by NADPH oxidase 4 (Nox4), a constitutively active enzyme, has been associated with oxygen sensing, vasomotor control, cellular proliferation, differentiation, migration, apoptosis, senescence, fibrosis, and angiogenesis. Further, elevated expression of Nox4 has been reported in a number of cardiovascular diseases, including atherosclerosis, hypertension, cardiac failure, ischemic stroke, and PAH. However, the cellular location of Nox4 and its contribution to aberrant vascular remodeling in PAH remains poorly understood. The goal of this review is to summarize the recent literature on the enzymatic regulation of Nox4 in the production of ROS in PAH. In the vascular wall, Nox4 is present in fibroblasts, a primary cell of the adventitia, and matches the adventitial location of ROS production in PAH. Further, in adventitial fibroblasts, Nox4 overexpression stimulates migration and proliferation as well as matrix gene expression. Collectively, reports indicate that Nox4 contributes to altered fibroblast behavior, ROS production leading to hypertensive vascular remodeling and the development of PAH. Finally, we address the functional significance of Nox4 in fibroblasts, and also suggest an "outside in" (adventitial) process of vascular remodeling that is mediated by Nox4, which although has physiological roles in the intimal layer (i.e., endothelium), may also have pathologic importance in the adventitial layer of the vascular wall through signaling in fibroblasts.

Cardiopulmonary protective effects of the selective FXR agonist obeticholic acid in the rat model of monocrotaline-induced pulmonary hypertension

Farnesoid X receptor (FXR) activation by obeticholic acid (OCA) has been demonstrated to inhibit inflammation and fibrosis development and even induce fibrosis regression in liver, kidney and intestine in multiple disease models. OCA also inhibits liver fibrosis in nonalcoholic steatohepatitis patients. FXR activation has also been demonstrated to suppress the inflammatory response and to promote lung repair after lung injury. This study investigated the effects of OCA treatment (3, 10 or 30mg/kg, daily for 5days a week, for 7 and/or 28 days) on inflammation, tissue remodeling and fibrosis in the monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) rat model. Treatment with OCA attenuated MCT-induced increased pulmonary arterial wall thickness and right ventricular hypertrophy, by i) blunting pathogenic inflammatory mechanisms (downregulation of interleukin 6, IL-6, and monocyte chemoattractant protein-1, MCP-1) and ii) enhancing protective mechanisms counteracting fibrosis and endothelial/mesenchymal transition. MCT-injected rats also showed a marked decrease of pulmonary artery responsiveness to both endothelium-dependent and independent relaxant stimuli, such as acetylcholine and a nitric oxide donor, sodium nitroprusside. Administration of OCA (30mg/kg) normalized this decreased responsiveness. Accordingly, OCA treatment induced profound beneficial effects on lung histology. In particular, both OCA doses markedly reduced the MCT-induced medial wall thickness increase in small pulmonary arteries. To evaluate the objective functional improvement by OCA treatment of MCT-induced PAH, we performed a treadmill test and measured duration of exercise. MCT significantly reduced, and OCA normalized treadmill endurance. Results with OCA were similar, or even superior, to those obtained with tadalafil, a well-established treatment of PAH. In conclusion, OCA treatment demonstrates cardiopulmonary protective effects, modulating lung vascular remodeling, reducing right ventricular hypertrophy and significantly improving exercise capacity. Thus, OCA can restore the balance between relaxant and contractile pathways in the lung, promoting cardiopulmonary protective actions.

A Survey of Strategies to Modulate the Bone Morphogenetic Protein Signaling Pathway: Current and Future Perspectives

Bone morphogenetic proteins (BMPs) constitute the largest subdivision of the TGF-β family of ligands and are unequivocally involved in regulating stem cell behavior. Appropriate regulation of canonical BMP signaling is critical for the development and homeostasis of numerous human organ systems, as aberrations in the BMP pathway or its regulation are increasingly associated with diverse human pathologies. In this review, we provide a wide-perspective on strategies that increase or decrease BMP signaling. We briefly outline the current FDA-approved approaches, highlight emerging next-generation technologies, and postulate prospective avenues for future investigation. We also detail how activating other pathways may indirectly modulate BMP signaling, with a particular emphasis on the relationship between the BMP and Activin/TGF-β pathways.

Salvianolic acid A attenuates vascular remodeling in a pulmonary arterial hypertension rat model

AIM

The current therapeutic approaches have a limited effect on the dysregulated pulmonary vascular remodeling, which is characteristic of pulmonary arterial hypertension (PAH). In this study we examined whether salvianolic acid A (SAA) extracted from the traditional Chinese medicine 'Dan Shen' attenuated vascular remodeling in a PAH rat model, and elucidated the underlying mechanisms.

METHODS

PAH was induced in rats by injecting a single dose of monocrotaline (MCT 60 mg/kg, sc). The rats were orally treated with either SAA (0.3, 1, 3 mg·kg(-1)·d(-1)) or a positive control bosentan (30 mg·kg(-1)·d(-1)) for 4 weeks. Echocardiography and hemodynamic measurements were performed on d 28. Then the hearts and lungs were harvested, the organ indices and pulmonary artery wall thickness were calculated, and biochemical and histochemical analysis were conducted. The levels of apoptotic and signaling proteins in the lungs were measured using immunoblotting.

RESULTS

Treatment with SAA or bosentan effectively ameliorated MCT-induced pulmonary artery remodeling, pulmonary hemodynamic abnormalities and the subsequent increases of right ventricular systolic pressure (RVSP). Furthermore, the treatments significantly attenuated MCT-induced hypertrophic damage of myocardium, parenchymal injury and collagen deposition in the lungs. Moreover, the treatments attenuated MCT-induced apoptosis and fibrosis in the lungs. The treatments partially restored MCT-induced reductions of bone morphogenetic protein type II receptor (BMPRII) and phosphorylated Smad1/5 in the lungs.

CONCLUSION

SAA ameliorates the pulmonary arterial remodeling in MCT-induced PAH rats most likely via activating the BMPRII-Smad pathway and inhibiting apoptosis. Thus, SAA may have therapeutic potential for the patients at high risk of PAH.

Administration of antioxidant peptide SS-31 attenuates transverse aortic constriction-induced pulmonary arterial hypertension in mice

AIM

Antioxidant peptide SS-31 is a class of cell-permeable small peptides, which selectively resides on the inner mitochondrial membrane and possesses intrinsic mitochondrial protective capacities. In this study we investigated the therapeutic effects of antioxidant peptide SS-31 on transverse aortic constriction (TAC)-induced pulmonary arterial hypertension (PAH) in a murine model.

METHODS

Adult male mice were divided into 3 groups: sham-operated mice, TAC mice, and TAC+SS-31 mice that underwent TAC surgery and received SS-31 (2 mg/d, ip) for 60 d. The right ventricular systolic blood pressure (RVSBP) was measured on d 60 prior to sacrificing the mice; then their right heart and lung tissues were collected for histological and biochemical examinations. Lung injury scores were defined by the increased crowded area and decreased number of alveolar sacs.

RESULTS

TAC mice showed significantly higher RVSBP compared with sham-operated mice, the elevation was substantially suppressed in TAC+SS-31 mice. The same pattern of changes was found in pulmonary levels of oxidative stress proteins (NOX-1/NOX-2/oxidized proteins), cytosolic cytochrome c, biomarkers related to inflammation (MMP-9/TNF-α/iNOS), calcium overload index (TRPC1, 2, 4, 6), apoptosis (mitochondrial BAX, cleaved caspase 3/PARP), fibrosis (Smad3/TGF-β), hypoxic (HIF-1α), DNA damage (γ-H2AX) and endothelial function (eNOS/ET-1R), as well as in lung injury score, number of muscularized vessels in lungs, number of TRPC1(+) and HIF-1α(+) cells in pulmonary artery, and number of γ-H2AX(+) and Ki-67(+) cells in lung parenchyma. An opposite pattern of changes was observed in pulmonary anti-fibrotic markers (Smad1/5, BMP-2), number of small vessels, and number of alveolar sacs. In contrast, the levels of antioxidant proteins (HO-1/NQO-1/GR/GPx) in lung parenchyma were progressively and significantly increased from sham-operated mice, TAC mice to TAC+SS-31 mice.

CONCLUSION

Antioxidant peptide SS-31 administration effectively attenuates TAC-induced PAH in mice.

Expression and role of connexin-based gap junctions in pulmonary inflammatory diseases

Connexins are transmembrane proteins that can generate intercellular communication channels known as gap junctions. They contribute to the direct movement of ions and larger cytoplasmic solutes between various cell types. In the lung, connexins participate in a variety of physiological functions, such as tissue homeostasis and host defence. In addition, emerging evidence supports a role for connexins in various pulmonary inflammatory diseases, such as asthma, pulmonary hypertension, acute lung injury, lung fibrosis or cystic fibrosis. In these diseases, the altered expression of connexins leads to disruption of normal intercellular communication pathways, thus contributing to various pathophysiological aspects, such as inflammation or tissue altered reactivity and remodeling. The present review describes connexin structure and organization in gap junctions. It focuses on connexins in the lung, including pulmonary bronchial and arterial beds, by looking at their expression, regulation and physiological functions. This work also addresses the issue of connexin expression alteration in various pulmonary inflammatory diseases and describes how targeting connexin-based gap junctions with pharmacological tools, synthetic blocking peptides or genetic approaches, may open new therapeutic perspectives in the treatment of these diseases.

Salvia Miltiorrhiza Bge.f.alba Ameliorates the Progression of Monocrotaline-Induced Pulmonary Hypertension by Protecting Endothelial Injury in Rats

Pulmonary hypertension (PH) is a life-threatening disease that is characterized by elevated pulmonary blood pressure, abnormally thickened pulmonary arteries, and right ventricular hypertrophy. Monocrotaline (MCT) has been used to generate an experimental model of PH in rats, with PH initiated from injuries of lung vascular endothelium. Salvia Miltiorrhiza Bge.f.alba is a widely used traditional herb in China, known to exert protective effects on vascular endothelial cell injury in animal experiments. However, the role of Salvia Miltiorrhiza Bge.f.alba in PH remains unclear. Thus, we investigated the effects of the aqueous extract of Salvia Miltiorrhiza Bge.f.alba (AESM) on MCT-induced PH and explored the pertinent mechanism. PH was induced in rats by a single subcutaneous injection of MCT (60 mg/kg body weight). Low or high dose (4.6 g/kg or 14 g/kg body weight) of AESM was then administered orally for 21 days to PH rats. Hemodynamic study showed that AESM reduced mean pulmonary artery pressure and improved right ventricle function. Lung pathological analysis revealed that AESM reduced wall thickness and lumen stenosis of pulmonary vessels. Also AESM ameliorated right ventricular hypertrophy. Measurement of biochemical parameters indicated that AESM decreased endothelin-1 and thromboxane A2 in plasma and increased nitrogen monoxide and prostacyclin in the plasma and reduced the increase of transforming growth factor β1 in lung tissue. Our results suggest that AESM may ameliorate the progression of MCT-induced PH in rats, at least in part by its protective effect on endothelial injury. Therefore, Salvia Miltiorrhiza Bge.f.alba could be useful in the treatment of PH.

The lung communication network

The different types of cells in the lung, from the conducting airway epithelium to the alveolar epithelium and the pulmonary vasculature, are interconnected by gap junctions. The specific profile of gap junction proteins, the connexins, expressed in these different cell types forms compartments of intercellular communication that can be further shaped by the release of extracellular nucleotides via pannexin1 channels. In this review, we focus on the physiology of connexins and pannexins and describe how this lung communication network modulates lung function and host defenses in conductive and respiratory airways.

Reducing TRPC1 Expression through Liposome-Mediated siRNA Delivery Markedly Attenuates Hypoxia-Induced Pulmonary Arterial Hypertension in a Murine Model

We tested the hypothesis that Lipofectamine siRNA delivery to deplete transient receptor potential cation channel (TRPC) 1 protein expression can suppress hypoxia-induced pulmonary arterial hypertension (PAH) in mice. Adult male C57BL/6 mice were equally divided into group 1 (normal controls), group 2 (hypoxia), and group 3 (hypoxia + siRNA TRPC1). By day 28, right ventricular systolic pressure (RVSP), number of muscularized arteries, right ventricle (RV), and lung weights were increased in group 2 than in group 1 and reduced in group 3 compared with group 2. Pulmonary crowded score showed similar pattern, whereas number of alveolar sacs exhibited an opposite pattern compared to that of RVSP in all groups. Protein expressions of TRPCs, HIF-1α, Ku-70, apoptosis, and fibrosis and pulmonary mRNA expressions of inflammatory markers were similar pattern, whereas protein expressions of antifibrosis and VEGF were opposite to the pattern of RVSP. Cellular markers of pulmonary DNA damage, repair, and smooth muscle proliferation exhibited a pattern similar to that of RVSP. The mRNA expressions of proapoptotic and hypertrophy biomarkers displayed a similar pattern, whereas sarcomere length showed an opposite pattern compared to that of RVSP in all groups. Lipofectamine siRNA delivery effectively reduced TRPC1 expression, thereby attenuating PAH-associated RV and pulmonary arteriolar remodeling.

The role of phosphodiesterase inhibitors in the management of pulmonary vascular diseases

Phosphodiesterase inhibitors (PDE) can be used as therapeutic agents for various diseases such as dementia, depression, schizophrenia and erectile dysfunction in men, as well as congestive heart failure, chronic obstructive pulmonary disease, rheumatoid arthritis, other inflammatory diseases, diabetes and various other conditions. In this review we will concentrate on one type of PDE, mainly PDE5 and its role in pulmonary vascular diseases.

Benefit of combined therapy with nicorandil and colchicine in preventing monocrotaline-induced rat pulmonary arterial hypertension

This study tested the hypothesis that combined therapy with nicorandil and colchicine is superior to either alone in attenuating monocrotaline (MCT)-induced rat pulmonary arterial hypertension (PAH). Adult male Sprague-Dawley rats (n=50) were equally randomized into group 1 (sham control), group 2 [MCT (60 mg/kg i.p.)], group 3 [MCT-Nicorandil (5.0 mg/kg/day)], group 4 [MCT-Colchicine (1.0 mg/kg/day)], and group 5 (MCT-Nicorandil-Colchicine). Drugs were given on day 5. All animals were sacrificed on day 90 after MCT administration. Right ventricular systolic blood pressure (RVSBP) and RV weight were increased in group 2 compared to group 1, reduced in groups 3 and 4 compared to group 2, and further reduced in group 5, whereas arterial-oxygen saturation showed an opposite pattern (all p<0.001). Pulmonary damage severity (thickened alveolar septum and pulmonary arteriolar wall, decreased alveolar-sac numbers), number of CD3+ cells, and protein expressions of inflammatory (MMP-9, NF-κB, VCAM-1, angiotensin II-receptor), apoptotic (Bax, caspase 3, cleaved PARP), and fibrotic (TGF-β, Smad3) biomarkers showed an identical pattern compared to that of RVSBP, whereas pulmonary expressions of anti-apoptotic (Bcl-2) and anti-fibrotic (BMP-2, Smad1/5) biomarkers displayed a reverse pattern (all p<0.01). The protein expressions of RV damage markers (BNP, caspase 3) were increased, whereas expression of biomarker for RV functional preservation (Cx43) was reduced in group 2 compared with group 1, elevated in groups 3 and 4 compared to group 2, and further increased in group 5 (all p<0.01). Combined therapy with nicorandil and colchicine is superior to either alone in attenuating MCT-induced PAH in rats.

Paradoxical impairment of angiogenesis, endothelial function and circulating number of endothelial progenitor cells in DPP4-deficient rat after critical limb ischemia

Introduction

We hypothesized that dipeptidyl peptidase-IV (DPP4) may impair angiogenesis, endothelial function, and the circulating number of endothelial progenitor cells (EPC) in a model of critical limb ischemia (CLI) through ligating the left femoral artery using DPP4-deficient rats.

Methods

Adult male DPP4-deficient (DPP4^D) rats (n = 18) were equally divided into CLI only (DPP4^D-CLI) and CLI treated by granulocyte colony-stimulating factor (GCSF) (DPP4^D-CLI-GCSF). For comparison, age-matched wild-type (WT) Fischer 344 rats (n = 18) were randomized into two groups receiving identical treatment compared to their DPP4-deficient counterparts and labeled as WT-CLI (n = 9) and WT-CLI-GCSF (n = 9), respectively.

Results

The circulating number of EPCs (CD31+, CD34+, CD133, C-kit+) was significantly lower in DPP4-deficient than in WT rats on post-CLI days 1 and 4 (all P < 0.01). The ratio of ischemia/normal blood flow was remarkably lower in DPP4^D-CLI-GCSF rats than in WT-CLI-GCSF animals on post-CLI Day 14 (all P < 0.01). Protein expressions of pro-angiogenic factors (endothelial nitric oxide synthase (eNOS), CXCR4, SDF-1α, vascular endothelial growth factor (VEGF)) were remarkably higher in WT-CLI than in DPP4^D-CLI rats, and higher in WT-CLI-GCSF than in DPP4^D-CLI-GCSF animals (all P < 0.01). Moreover, the numbers of small vessel in the ischemic area were substantially higher in WT-CLI-GCSF than in DPP4^D-CLI-GCSF rats (P < 0.001). Furthermore, vasorelaxation and nitric oxide production of the normal femoral artery were significantly reduced in DPP4-deficient than in WT Fischer rats (all P < 0.01).

Conclusions

Contrary to our hypothesis, DPP4-deficient rats were inferior to age-matched WT Fischer rats in terms of angiogenesis, endothelial function, circulating EPC number and response to GCSF, suggesting a positive role of DPP4 in maintaining vascular function and tissue perfusion in this experimental setting.

Sildenafil improves long-term effect of endothelial progenitor cell-based treatment for monocrotaline-induced rat pulmonary arterial hypertension

BACKGROUND AIMS

We hypothesized that the long-term therapeutic effect of combined sildenafil and bone marrow-derived endothelial progenitor cells (BMDEPCs) on monocrotaline (MCT)-induced rat pulmonary arterial hypertension (PAH) is superior to either treatment alone.

METHODS

Male Sprague-Dawley rats (n = 40) were equally divided into normal controls, MCT (65 mg/kg, subcutaneously) only, MCT + sildenafil (25 mg/kg/day, orally), MCT + BMDEPCs (2.0 × 10(6) autologous cells, intravenously) and MCT + sildenafil+ BMDEPCs. BMDEPCs and sildenafil were given on day 21 after MCT administration. Animals were sacrificed by day 90 after MCT administration.

RESULTS

The apoptotic (caspase 3, Bax) and inflammatory (tumor necrosis factor-α, matrix metalloproteinase-9) biomarkers in right ventricle and lung and pulmonary expressions of fibrotic biomarkers (transforming growth factor-β, p-Smad3) and connexin 43 protein were lower in monotherapy groups (i.e., MCT + sildenafil and MCT + BMDEPCs) and further decreased in normal controls and combined treatment groups (i.e., MCT + sildenafil + BMDEPCs) compared with untreated animals (i.e., MCT only) (all P < 0.01). Expressions of anti-fibrotic biomarkers (bone morphogenetic protein-2, p-Smad1/5) and numbers of alveolar sacs and arterioles in lung were higher in monotherapy groups and further increased in normal controls and combined treatment groups compared with untreated animals (all P < 0.005). In right ventricle, connexin 43 and α-myosin heavy chain (MHC) expressions were higher in the monotherapy groups and further elevated in normal controls and combined treatment groups compared with untreated animals, whereas β-MHC exhibited the opposite pattern (all P < 0.01). Right ventricular systolic pressure and weight were lower in the monotherapy animals and further reduced in normal controls and combined treatment groups compared with untreated animals (all P < 0.0001).

CONCLUSIONS

Combined therapy with BMDEPCs and sildenafil was superior to either treatment alone in attenuating rodent MCT-induced PAH.

Assessment of the endothelial functions in monocrotaline-induced pulmonary hypertension

Pulmonary hypertension (PH) is a life-threatening disease that causes endothelial dysfunction in the pulmonary vascular bed. Systemic endothelial dysfunction has also been reported in PH. This study compared the systemic and pulmonary vascular responses and some blood biomarkers of endothelial function in monocrotaline (MCT)-induced PH of rats. It also investigated the effect of sildenafil and iloprost treatment. MCT application induced elevation in the right ventricular pressures of the rat heart that had been reversed by sildenafil and iloprost treatment. Acetylcholine-induced endothelium-dependent relaxations of the isolated pulmonary artery were decreased in the PH group and this failure was reversed by sildenafil and iloprost treatment. Acetylcholine-induced endothelium-dependent relaxations of the isolated thoracic aorta were similar in all groups. Serotonin-induced contractions of the pulmonary artery were augmented by PH. In the isolated aorta, serotonin-stimulated contraction was not different in the control and MCT groups, but sildenafil and iloprost treatment decreased serotonin responses. The nitric oxide (NO) level in systemic circulation was not significantly changed by PH. However, sildenafil and iloprost treatments caused a decrease in the plasma level of NO. Asymmetric dimethylarginine levels in plasma were significantly decreased after MCT application and were not recovered by sildenafil and iloprost treatment. Total antioxidant capacity and H2S level of plasma were similar in all groups. Results of this study showed that MCT-induced PH caused specific toxic effects on pulmonary vasculature without any functional effects on the aorta. In addition, it was also demonstrated that sildenafil and iloprost treatments were effective in the MCT-induced PH.

Continuing exposure to low-dose nonylphenol aggravates adenine-induced chronic renal dysfunction and role of rosuvastatin therapy

Background

Nonylphenol (NP), an environmental organic compound, has been demonstrated to enhance reactive-oxygen species (ROS) synthesis. Chronic exposure to low-dose adenine (AD) has been reported to induce chronic kidney disease (CKD).

Methods

In this study, we tested the hypothesis that chronic exposure to NP will aggravate AD-induced CKD through increasing generations of inflammation, ROS, and apoptosis that could be attenuated by rosuvastatin. Fifty male Wistar rats were equally divided into group 1 (control), group 2 (AD in fodder at a concentration of 0.25%), group 3 (NP: 2 mg/kg/day), group 4 (combined AD & NP), and group 5 (AD-NP + rosuvastatin: 20 mg/kg/day). Treatment was continued for 24 weeks for all animals before being sacrificed.

Results

By the end of 24 weeks, serum blood urea nitrogen (BUN) and creatinine levels were increased in group 4 than in groups 1–3, but significantly reduced in group 5 as compared with group 4 (all p < 0.05). Histopathology scorings of renal-parenchymal and tubular damages were significantly higher in group 4 than in groups 1–3, but remarkably lower in group 5 compared with group 4 (all p < 0.01). Both gene and protein levels of inflammation, oxidative stress, ROS, and cellular apoptosis were remarkably higher in group 4 compared with groups 1–3, but lowered in group 5 than in group 4 (all p < 0.001). Conversely, both gene and protein levels of anti-oxidants, anti-inflammation and anti-apoptosis were markedly increased in group 5 compared with group 4 (all p < 0.001).

Conclusion

NP worsened AD-induced CKD that could be reversed by rosuvastatin therapy.

Resveratrol reverses monocrotaline-induced pulmonary vascular and cardiac dysfunction: a potential role for atrogin-1 in smooth muscle

Arterial remodeling contributes to elevated pulmonary artery (PA) pressures and right ventricular hypertrophy seen in pulmonary hypertension (PH). Resveratrol, a sirtuin-1 (SIRT1) pathway activator, can prevent the development of PH in a commonly used animal model, but it is unclear whether it can reverse established PH pathophysiology. Furthermore, atrophic ubiquitin ligases, such as atrogin-1 and MuRF-1, are known to be induced by SIRT1 activators but have not been characterized in hypertrophic vascular disease. Therefore, we hypothesized that monocrotaline (MCT)-induced PH would attenuate atrophy pathways in the PA while, conversely, SIRT1 activation (resveratrol) would reverse indices of PH and restore atrophic gene expression. Thus, we injected Sprague-Dawley rats with MCT (50 mg/kg i.p.) or saline at Day 0, and then treated with oral resveratrol or sildenafil from days 28-42 post-MCT injection. Oral resveratrol attenuated established MCT-induced PH indices, including right ventricular systolic pressure, right ventricular hypertrophy, and medial thickening of intrapulmonary arteries. Resveratrol also normalized PA atrogin-1 mRNA expression, which was significantly reduced by MCT. In cultured human PA smooth muscle cells (hPASMC), resveratrol significantly inhibited PDGF-stimulated proliferation and cellular hypertrophy, which was also associated with improvements in atrogin-1 levels. In addition, SIRT1 inhibition augmented hPASMC proliferation, as assessed by DNA mass, and suppressed atrogin mRNA expression. These findings demonstrate an inverse relationship between indices of PH and PA atrogin expression that is SIRT1 dependent and may reflect a novel role for SIRT1 in PASMCs opposing cellular hypertrophy and proliferation.

Autologous transplantation of adipose-derived mesenchymal stem cells markedly reduced acute ischemia-reperfusion lung injury in a rodent model

Background

This study tested the hypothesis that autologous transplantation of adipose-derived mesenchymal stem cells (ADMSCs) can effectively attenuate acute pulmonary ischemia-reperfusion (IR) injury.

Methods

Adult male Sprague-Dawley (SD) rats (n = 24) were equally randomized into group 1 (sham control), group 2 (IR plus culture medium only), and group 3 (IR plus intravenous transplantation of 1.5 × 10⁶ autologous ADMSCs at 1h, 6h, and 24h following IR injury). The duration of ischemia was 30 minutes, followed by 72 hours of reperfusion prior to sacrificing the animals. Blood samples were collected and lungs were harvested for analysis.

Results

Blood gas analysis showed that oxygen saturation (%) was remarkably lower, whereas right ventricular systolic pressure was notably higher in group 2 than in group 3 (all p < 0.03). Histological scoring of lung parenchymal damage was notably higher in group 2 than in group 3 (all p < 0.001). Real time-PCR demonstrated remarkably higher expressions of oxidative stress, as well as inflammatory and apoptotic biomarkers in group 2 compared with group 3 (all p < 0.005). Western blot showed that vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule (ICAM)-1, oxidative stress, tumor necrosis factor-α and nuclear factor-κB were remarkably higher, whereas NAD(P)H quinone oxidoreductase 1 and heme oxygenase-1 activities were lower in group 2 compared to those in group 3 (all p < 0.004). Immunofluorescent staining demonstrated notably higher number of CD68+ cells, but significantly fewer CD31+ and vWF+ cells in group 2 than in group 3.

Conclusion

ADMSC therapy minimized lung damage after IR injury in a rodent model through suppressing oxidative stress and inflammatory reaction.

Estrogen rescues preexisting severe pulmonary hypertension in rats

RATIONALE

Pulmonary hypertension (PH) is characterized by progressive increase in pulmonary artery pressure leading to right ventricular (RV) hypertrophy, RV failure, and death. Current treatments only temporarily reduce severity of the disease, and an ideal therapy is still lacking.

OBJECTIVES

Estrogen pretreatment has been shown to attenuate development of PH. Because PH is not often diagnosed early, we examined if estrogen can rescue preexisting advanced PH.

METHODS

PH was induced in male rats with monocrotaline (60 mg/kg). At Day 21, rats were either treated with 17-β estradiol or estrogen (E2, 42.5 μg/kg/d), estrogen receptor-β agonist (diarylpropionitrile, 850 μg/kg/d), or estrogen receptor α-agonist (4,4',4"-[4-Propyl-(1H)-pyrazole-1,3,5-triyl] trisphenol, 850 μg/kg/d) for 10 days or left untreated to develop RV failure. Serial echocardiography, cardiac catheterization, immunohistochemistry, Western blot, and real-time polymerase chain reaction were performed.

MEASUREMENTS AND MAIN RESULTS

Estrogen therapy prevented progression of PH to RV failure and restored lung and RV structure and function. This restoration was maintained even after removal of estrogen at Day 30, resulting in 100% survival at Day 42. Estradiol treatment restored the loss of blood vessels in the lungs and RV. In the presence of angiogenesis inhibitor TNP-470 (30 mg/kg) or estrogen receptor-β antagonist (PHTPP, 850 μg/kg/d), estrogen failed to rescue PH. Estrogen receptor-β selective agonist was as effective as estrogen in rescuing PH.

CONCLUSIONS

Estrogen rescues preexisting severe PH in rats by restoring lung and RV structure and function that are maintained even after removal of estrogen. Estrogen-induced rescue of PH is associated with stimulation of cardiopulmonary neoangiogenesis, suppression of inflammation, fibrosis, and RV hypertrophy. Furthermore, estrogen rescue is likely mediated through estrogen receptor-β.

Connexins as therapeutic targets in lung disease

INTRODUCTION

The lung is a mechanically active system exposed to the external environment and is particularly sensitive to injury and inflammation. Studies have identified intercellular communication pathways that promote proper lung function in response to injury and disease. These pathways involve connexins (Cxs) and gap junctional intercellular communication (GJIC).

AREAS COVERED IN THIS REVIEW

The functional expression of Cxs in airway epithelium and vasculature, under normal and pathological conditions, is reviewed. Inhibition of GJIC and/or silencing of Cxs have been shown to modulate the course of disease development. Cx-based channels: i) coordinate ciliary beating and fluid transport to promote clearance of particulates, ii) regulate secretion of pulmonary surfactant, in response to deep inhalation by interconnecting type I and type II alveolar epithelial cells, and iii) are key mediators of pro- and anti-inflammatory signalling by the pulmonary endothelium, in order to modulate leukocyte recruitment from the circulation.

EXPERT OPINION

Cx-based channels play several central roles in promoting a regulated inflammatory response and facilitating lung repair, thus enabling the pulmonary epithelium and vasculature to behave as integrated systems. Several pathologies can disrupt the normal communication pathways required for proper lung function, including acute lung injury, asthma, cystic fibrosis, pulmonary fibrosis and cancer.

Early combined treatment with sildenafil and adipose-derived mesenchymal stem cells preserves heart function in rat dilated cardiomyopathy

Background

We investigated whether early combined autologous adipose-derived mesenchymal stem cell (ADMSC) and sildenafil therapy offers an additive benefit in preserving heart function in rat dilated cardiomyopathy (DCM).

Methods

Adult Lewis rats (n = 8 per group) were divided into group 1 (normal control), group 2 (saline-treated DCM rats), group 3 [2.0 × 10⁶ ADMSC implanted into left ventricular (LV) myocardium of DCM rats], group 4 (DCM rats with sildenafil 30 mg/kg/day, orally), and group 5 (DCM rats with combined ADMSC-sildenafil). Treatment was started 1 week after DCM induction and the rats were sacrificed on day 90.

Results

The results showed that mitochondrial protein expressions of connexin43 and cytochrome-C were lowest in group 2, and lower in groups 3 and 4 than in group 5 (p < 0.002). Conversely, oxidative index was highest in group 2, and also higher in groups 3 and 4 than in group 5 (p < 0.0003). The mRNA expressions of interleukin (IL)-10, Gro/IL-8, endothelial nitric oxide synthase, and Bcl-2 were lowest in group 2, and lower in groups 3 and 4 compared with group 5 (p < 0.0001). The mRNA expressions of matrix metalloproteinase-9, Bax, caspase 3, and stromal-cell derived factor-1α were highest in group 2, and higher in groups 3 and 4 than in group 5 (p < 0.0004). Apoptosis and fibrosis in LV myocardium were most prominent in group 2 and higher in groups 3 and 4 than in group 5, whereas angiogenesis and LV ejection fraction were lowest in group 2 and lower in groups 3 and 4 than in group 5 (p < 0.003).

Conclusion

Early combined ADMSC/sildenafil is superior to either treatment alone in preserving LV function.