TRPC4 aggravates hypoxic pulmonary hypertension by promoting pulmonary endothelial cell apoptosis.

Pulmonary hypertension (PH) is a devastating disease that lacks effective treatment options and is characterized by severe pulmonary vascular remodeling. Pulmonary arterial endothelial cell (PAEC) dysfunction drives the initiation and pathogenesis of pulmonary arterial hypertension. Canonical transient receptor potential (TRPC) channels, a family of Ca2+-permeable channels, play an important role in various diseases. However, the effect and mechanism of TRPCs on PH development have not been fully elucidated. Among the TRPC family members, TRPC4 expression was markedly upregulated in PAECs from hypoxia combined with SU5416 (HySu)-induced PH mice and monocrotaline (MCT)-treated PH rats, as well as in hypoxia-exposed PAECs, suggesting that TRPC4 in PAECs may participate in the occurrence and development of PH. In this study, we aimed to investigate whether TRPC4 in PAECs has an aggravating effect on PH and elucidate the molecular mechanisms. We observed that hypoxia treatment promoted PAEC apoptosis through a caspase-12/endoplasmic reticulum stress (ERS)-dependent pathway. Knockdown of TRPC4 attenuated hypoxia-induced apoptosis and caspase-3/caspase-12 activity in PAECs. Accordingly, adeno-associated virus (AAV) serotype 6-mediated pulmonary endothelial TRPC4 silencing (AAV6-Tie-shRNA-TRPC4) or TRPC4 antagonist suppressed PH progression as evidenced by reduced right ventricular systolic pressure (RVSP), pulmonary vascular remodeling, PAEC apoptosis and reactive oxygen species (ROS) production. Mechanistically, unbiased RNA sequencing (RNA-seq) suggested that TRPC4 deficiency suppressed the expression of the proapoptotic protein sushi domain containing 2 (Susd2) in hypoxia-exposed mouse PAECs. Moreover, TRPC4 activated hypoxia-induced PAEC apoptosis by promoting Susd2 expression. Therefore, inhibiting TRPC4 ameliorated PAEC apoptosis and hypoxic PH in animals by repressing Susd2 signaling, which may serve as a therapeutic target for the management of PH.

Cannabidiol may prevent the development of congestive hepatopathy secondary to right ventricular hypertrophy associated with pulmonary hypertension in rats.

BACKGROUND: Pulmonary hypertension (PH) can cause right ventricular (RV) failure and subsequent cardiohepatic syndrome referred to as congestive hepatopathy (CH). Passive blood stasis in the liver can affect inflammation, fibrosis, and ultimately cirrhosis. Cannabidiol (CBD) has many beneficial properties including anti-inflammatory and reduces RV systolic pressure and RV hypertrophy in monocrotaline (MCT)-induced PH in rats. Thus, it suggests that CBD may have the potential to limit CH development secondary to RV failure. The present study aimed to determine whether chronic administration of CBD can inhibit the CH secondary to RV hypertrophy associated with MCT-induced PH. METHODS: The experiments involved rats with and without MCT-induced PH. CBD (10 mg/kg) or its vehicle was administered once daily for 3 weeks after MCT injection (60 mg/kg). RESULTS: Monocrotaline administration increased the liver/body weight ratio. In histology examinations, we observed necrosis and vacuolar degeneration of hepatocytes as well as sinusoidal congestion. In biochemical studies, we observed increased levels of nuclear factor-κappa B (NF-κB), tumour necrosis factor-alpha (TNA-α), interleukin 1 beta (IL-1ß), and interleukin 6 (IL-6). CBD administration to PH rats reduced the liver/body weight ratio, improved the architecture of the liver, and inhibited the formation of necrosis. Cannabidiol also decreased the level of NF-κB, TNF-α, IL-1ß and IL-6. CONCLUSIONS: The studies show that CBD can protect the liver from CH probably through attenuating PH, protective effects on the RV, and possibly direct anti-inflammatory effects on liver tissue through regulation of the NF-κB pathway.

Tumor Necrosis Factor-α-Induced Protein-8-like 2 Transfected Adipose-Derived Stem Cells Regulated the Dysfunction of Monocrotaline Pyrrole-Induced Pulmonary Arterial Smooth Muscle Cells and Pulmonary Arterial Endothelial Cells.

ABSTRACT: Pulmonary arterial hypertension (PAH) is characterized by pulmonary arterial endothelial cell (PAEC) dysfunction and pulmonary arterial smooth muscle cell (PASMC) activation. For decades, the therapies for PAH based on stem cells have been shown to be effective. Meanwhile, tumor necrosis factor-α-induced protein-8-like 2 (TIPE2) promote the viability of human amniotic mesenchymal stem cells. Therefore, we aimed to explore the role of TIPE2 in adipose-derived stem cells (ADSCs) and the function of TIPE2-transfected ADSCs in the regulation of PAH. We first explored the role and underlying molecular mechanism of TIPE2 in viability and migration of ADSCs. Moreover, the ADSCs transfected with TIPE2 were cocultured with monocrotaline pyrrole (MCTP)-stimulated PASMCs or PAECs. The effects and mechanisms of TIPE2-transfected ADSCs on MCTP-induced PASMCs and PAECs were further investigated. The results showed that TIPE2 overexpression promoted viability and migration of ADSCs by activating the TLR4-ERK1/2 pathway. In addition, TIPE2-transfected ADSCs inhibited the abnormal proliferation and the impaired apoptosis of PASMCs via NF-κB signaling and promoted the conversion of PASMCs from synthetic to contractile. Meanwhile, TIPE2-transfected ADSCs reduced the apoptosis, endothelial-to-mesenchymal transition, and migration of PAECs via PI3K/AKT signaling after MCTP treatment. MCTP-induced oxidative stress and inflammation of PAECs were significantly decreased by TIPE2-transfected ADSCs. In rat model, TIPE2-ADSCs administration further decreased the monocrotaline-induced increase in the right ventricular systolic pressure and ratio of right ventricle weight/left ventricle and septa weight (L + S) and right ventricle weight/body weight compared with the ADSCs group. In conclusion, TIPE2-transfected ADSCs dramatically attenuated the PAH via inhibiting the dysfunction of PASMCs and PAECs.

Impact of inhalation exposure to cigarette smoke on the pathogenesis of pulmonary hypertension primed by monocrotaline in rats.

Extensive, long-term exposure to cigarette smoke (CS) was recently suggested to be a risk factor for pulmonary hypertension, although further validation is required. The vascular effects of CS share similarities with the etiology of pulmonary hypertension, including vascular inflammation and remodeling. Thus, we examined the influence of CS exposure on the pathogenesis of monocrotaline (MCT)-induced pulmonary hypertension, hypothesizing that smoking might accelerate the development of primed pulmonary hypertension. CS was generated from 3R4F reference cigarettes, and rats were exposed to CS by inhalation at total particulate matter concentrations of 100-300 µg/L for 4 h/day, 7 days/week for 4 weeks. Following 1 week of initial exposure, rats received 60 mg/kg MCT and were sacrificed and analyzed after an additional 3 weeks of exposure. MCT induced hypertrophy in pulmonary arterioles and increased the Fulton index, a measure of right ventricular hypertrophy. Additional CS exposure exacerbated arteriolar hypertrophy but did not further elevate the Fulton index. No significant alterations were observed in levels of endothelin-1 and vascular endothelial growth factor, or in hematological and serum biochemical parameters. Short-term inhalation exposure to CS exacerbated arteriolar hypertrophy in the lung, although this effect did not directly aggravate the overworked heart under the current experimental conditions.

Monocrotaline presence in the Crotalaria (Fabaceae) plant genus and its influence on arthropods in agroecosystems / Presença de monocrotalina em plantas do gênero Crotalaria (Fabaceae) e a sua influência sobre artrópodes nos agroecossistemas

Abstract Crotalaria (Fabaceae) occurs abundantly in tropical and subtropical regions and has about 600 known species. These plants are widely used in agriculture, mainly as cover plants and green manures, in addition to their use in the management of phytonematodes. A striking feature of these species is the production of pyrrolizidine alkaloids (PAs), secondary allelochemicals involved in plant defense against herbivores. In Crotalaria species, monocrotaline is the predominant PA, which has many biological activities reported, including cytotoxicity, tumorigenicity, hepatotoxicity and neurotoxicity, with a wide range of ecological interactions. Thus, studies have sought to elucidate the effects of this compound to promote an increase in flora and fauna (mainly insects and nematodes) associated with agroecosystems, favoring the natural biological control. This review summarizes information about the monocrotaline, showing such effects in these environments, both above and below ground, and their potential use in pest management programs.

Resumo Crotalaria (Linnaeus, 1753) (Fabaceae) ocorre abundantemente em regiões tropicais e subtropicais e tem cerca de 600 espécies conhecidas. Estas plantas são amplamente utilizadas na agricultura, principalmente como cobertura e adubos verdes, além da sua utilização no manejo de fitonematoides. Uma característica marcante destas espécies é a produção de alcalóides pirrolizidinicos (APs), aleloquímicos secundários envolvidos na defesa das plantas contra os herbívoros. Nas espécies de Crotalaria, a monocrotalina é a AP predominante, que tem muitas atividades biológicas relatadas, incluindo citotoxicidade, tumorigenicidade, hepatotoxicidade e neurotoxicidade, além de uma vasta gama de interações ecológicas. Assim, estudos têm procurado elucidar os efeitos desse composto para promover um incremento na flora e fauna (principalmente insetos e nematoides) associados aos agroecossistemas, favorecendo o controle biológico natural. Esta revisão compila informações sobre a monocrotalina, mostrando tais efeitos nesses ambientes, tanto acima como abaixo do solo e a sua potencial utilização em programas de manejo de pragas.

The Role of Rosmarinic Acid in the Protection Against Inflammatory Factors in Rats Model With Monocrotaline-Induced Pulmonary Hypertension: Investigating the Signaling Pathway of NFκB, OPG, Runx2, and P-Selectin in Heart.

ABSTRACT: Shortness of breath and syncope are common symptoms of right ventricular failure caused by pulmonary arterial hypertension (PAH), which is the result of blockage and increased pressure in the pulmonary arteries. There is a significant amount of evidence supporting the idea that inflammation and vascular calcification (VC) are important factors in PAH pathogenesis. Therefore, we aimed to investigate the features of the inflammatory process and gene expression involved in VC in monocrotaline (MCT)-induced PAH rats. MCT (60 mg/kg, i.p.) was used to induce PAH. Animals were given normal saline or rosmarinic acid (RA) (10, 15, and 30 mg/kg, gavage) for 21 days. An increase in right ventricular systolic pressure was evaluated as confirming PAH. To determine the level of inflammation in lung tissue, pulmonary edema and the total and differential white blood cell counts in the bronchoalveolar lavage fluid were measured. Also, the expression of NFκB, OPG, Runx2, and P-selectin genes was investigated to evaluate the level of VC in the heart. Our experiment showed that RA significantly decreased right ventricular hypertrophy, inflammatory factors, NFκB, Runx2, and P-selectin gene expression, pulmonary edema, total and differential white blood cell count, and increased OPG gene expression. Therefore, our research showed that RA protects against MCT-induced PAH by reducing inflammation and VC in rats.

Targeting Wnt-ß-Catenin-FOSL Signaling Ameliorates Right Ventricular Remodeling.

BACKGROUND: The ability of the right ventricle (RV) to adapt to an increased pressure afterload determines survival in patients with pulmonary arterial hypertension. At present, there are no specific treatments available to prevent RV failure, except for heart/lung transplantation. The wingless/int-1 (Wnt) signaling pathway plays an important role in the development of the RV and may also be implicated in adult cardiac remodeling. METHODS: Molecular, biochemical, and pharmacological approaches were used both in vitro and in vivo to investigate the role of Wnt signaling in RV remodeling. RESULTS: Wnt/ß-catenin signaling molecules are upregulated in RV of patients with pulmonary arterial hypertension and animal models of RV overload (pulmonary artery banding-induced and monocrotaline rat models). Activation of Wnt/ß-catenin signaling leads to RV remodeling via transcriptional activation of FOSL1 and FOSL2 (FOS proto-oncogene [FOS] like 1/2, AP-1 [activator protein 1] transcription factor subunit). Immunohistochemical analysis of pulmonary artery banding -exposed BAT-Gal (ß-catenin-activated transgene driving expression of nuclear ß-galactosidase) reporter mice RVs exhibited an increase in ß-catenin expression compared with their respective controls. Genetic inhibition of ß-catenin, FOSL1/2, or WNT3A stimulation of RV fibroblasts significantly reduced collagen synthesis and other remodeling genes. Importantly, pharmacological inhibition of Wnt signaling using inhibitor of PORCN (porcupine O-acyltransferase), LGKK-974 attenuated fibrosis and cardiac hypertrophy leading to improvement in RV function in both, pulmonary artery banding - and monocrotaline-induced RV overload. CONCLUSIONS: Wnt- ß-Catenin-FOSL signaling is centrally involved in the hypertrophic RV response to increased afterload, offering novel targets for therapeutic interference with RV failure in pulmonary hypertension.

A modified Fangji Huangqi decoction ameliorates pulmonary artery hypertension via phosphatidylinositide 3-kinases/protein kinase B-mediated regulation of proliferation and apoptosis of smooth muscle cells in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE: Pulmonary artery hypertension (PAH) is a progressive and fatal lung disease of multifactorial etiology, which arouses an enhanced interest in PAH disease therapy. Modified Fangji Huangqi decoction (MFJHQ), a traditional Chinese medicine (TCM) formula, has a crucial role in the treatment of PAH. However, the pharmacological roles and mechanisms of MFJHQ on PAH remain unknown. AIM OF THE STUDY: To investigate the effects and potential mechanism of MFJHQ on pulmonary vascular remodeling in PAH. MATERIAL AND METHODS: Ultra-performance liquid chromatography (UPLC) was employed to quantitate the principal components in MFJHQ. Rats were treated with MFJHQ by gavage for final 2 weeks in monocrotaline (MCT)-induced PAH rats. RNA-sequencing and network pharmacology analysis were performed to explore the potential mechanism. The primary rat pulmonary artery smooth muscle cells (PASMCs) were utilized to evaluate the regulatory effect of MFJHQ in vitro. RESULTS: Seven active components from MFJHQ were quantitated by UPLC. In rats with MCT-induced PAH, MFJHQ treatment significantly improved hemodynamic parameters, right ventricular hypertrophy index, lung function, and attenuated pulmonary vascular remodeling. Mechanistically, we further confirmed that MFJHQ inhibits MCT-induced phosphatidylinositide 3-kinases/protein kinase B (PI3K/Akt) pathway predicated by network pharmacology and RNA-sequencing analysis to reduce the proliferation of pulmonary arteries and promote pulmonary artery apoptosis in lung tissues. Additionally, MFJHQ hindered the proliferation and migration, and accelerated apoptosis in PDGF-BB-induced PASMCs in vitro, which can be enhanced by the presence of the PI3K inhibitor LY294002. CONCLUSIONS: Our results indicated that MFJHQ inhibited MCT-induced pulmonary vascular remodeling by decreasing proliferation and migration of PASMCs and promoting PASMC apoptosis through PI3K/Akt pathway, which provides a novel treatment option for PAH with multi-targeting mechanisms inspired by TCM theory.

Targeting erythrocyte-mediated hypoxia to alleviate lung injury induced by pyrrolizidine alkaloids.

Pyrrolizidine alkaloids (PAs) are widely distributed natural toxins and have been extensively studied for their hepatotoxicity. However, PA-induced pulmonary toxicity remains less studied regarding the initiating mechanism and treatment approaches. Our previous study demonstrated the formation of pyrrole-hemoglobin adducts after PA exposure in vivo, which is suspected to affect the oxygen-carrying capacity of erythrocytes [red blood cells (RBCs)] consequently. The present study aimed to investigate the effects of PAs on the oxygen-carrying capacity of RBCs and the potential of targeting RBC-mediated hypoxia to alleviate PA-induced lung injury. First, rats were treated with retrorsine (RTS) or monocrotaline (MCT) intravenously at 0.2 mmol/kg. The results of Raman spectrometry analysis on blood samples revealed both RTS and MCT significantly reduced the oxygen-carrying capacity of RBCs. Further, MCT (0.2 mmol/kg) was orally given to the rats with or without pretreatment with two doses of erythropoietin (Epo, 500 IU/kg/dose every other day), an RBC-stimulating agent. Biochemical and histological results showed pretreatment with Epo effectively reduced the cardiopulmonary toxicity induced by MCT. These findings provide the first evidence that adduction on hemoglobin, and the resulting RBC damage and impaired oxygen-carrying capacity, are the major initiating mechanism underlying PA-induced pulmonary arterial hypertension (PAH), while targeting the RBC damage is a potential therapeutic approach for PA-induced lung injury.

Role of Endothelin-1 in Right Atrial Arrhythmogenesis in Rabbits with Monocrotaline-Induced Pulmonary Arterial Hypertension.

Atrial arrhythmias are considered prominent phenomena in pulmonary arterial hypertension (PAH) resulting from atrial electrical and structural remodeling. Endothelin (ET)-1 levels correlate with PAH severity and are associated with atrial remodeling and arrhythmia. In this study, hemodynamic measurement, western blot analysis, and histopathology were performed in the control and monocrotaline (MCT, 60 mg/kg)-induced PAH rabbits. Conventional microelectrodes were used to simultaneously record the electrical activity in the isolated sinoatrial node (SAN) and right atrium (RA) tissue preparations before and after ET-1 (10 nM) or BQ-485 (an ET-A receptor antagonist, 100 nM) perfusion. MCT-treated rabbits showed an increased relative wall thickness in the pulmonary arterioles, mean cell width, cross-sectional area of RV myocytes, and higher right ventricular systolic pressure, which were deemed to have PAH. Compared to the control, the spontaneous beating rate of SAN-RA preparations was faster in the MCT-induced PAH group, which can be slowed down by ET-1. MCT-induced PAH rabbits had a higher incidence of sinoatrial conduction blocks, and ET-1 can induce atrial premature beats or short runs of intra-atrial reentrant tachycardia. BQ 485 administration can mitigate ET-1-induced RA arrhythmogenesis in MCT-induced PAH. The RA specimens from MCT-induced PAH rabbits had a smaller connexin 43 and larger ROCK1 and phosphorylated Akt than the control, and similar PKG and Akt to the control. In conclusion, ET-1 acts as a trigger factor to interact with the arrhythmogenic substrate to initiate and maintain atrial arrhythmias in PAH. ET-1/ET-A receptor/ROCK signaling may be a target for therapeutic interventions to treat PAH-induced atrial arrhythmias.

Inhibition of Bruton's Tyrosine Kinase Alleviates Monocrotaline-Induced Pulmonary Arterial Hypertension by Modulating Macrophage Polarization.

Macrophage accumulation and activation contribute to the development of pulmonary arterial hypertension (PAH), while Bruton's tyrosine kinase (BTK) is an important regulator for the activation and polarization of macrophage. However, the role of BTK in PAH remains unknown. In the present study, a selective BTK inhibitor (BTKi) BGB-3111 was applied to investigate the role of BTK in monocrotaline- (MCT-) induced PAH rat and phorbol myristate acetate- (PMA-) differentiated U937 macrophages. Our results showed that BTK was mainly distributed and upregulated in CD68+ macrophages in the lungs of PAH rats. Daily treated with BTKi BGB-3111 alleviated MCT-induced PAH, as indicated by the decrease in right ventricular systolic pressure (RVSP), attenuation in right ventricle hypertrophy and pulmonary vascular remodeling, reduction in perivascular collagen deposition, as well as inhibition of inflammation and endothelial-to-mesenchymal transition (EndMT) in the lung. Moreover, BTK inhibition suppressed MCT-induced recruitment of macrophages, especially the classical activated macrophages (M1) in the lung. In vitro, BGB-3111 significantly suppressed lipopolysaccharide- (LPS-) induced M1 polarization and proinflammatory cytokine production in U937-derived macrophages. The underlying mechanism is associated with the inhibition of NF-κB/MAPK pathways and nucleotide-binding oligomerization domain-like receptor with pyrin domain 3 (NLRP3) inflammasome activation. Furthermore, macrophage conditioned medium (CM) from LPS-induced M1 macrophages promoted migration and EndMT of HPAECs, while CM from BGB-3111-pretreated LPS-induced M1 macrophages failed to induce this response. These findings suggest that BTK inhibition alleviates PAH by regulating macrophage recruitment and polarization and may be a potential therapeutic strategy for the treatment of PAH.

Activation of Autophagy Induces Monocrotaline-Induced Pulmonary Arterial Hypertension by FOXM1-Mediated FAK Phosphorylation.

PURPOSE: It has been shown that activation of autophagy promotes the development of pulmonary arterial hypertension (PAH). Meanwhile, forkhead box M1 (FOXM1) has been found to induce autophagy in several types of cancer. However, it is still unclear whether FOXM1 mediates autophagy activation in PAH, and detailed mechanisms responsible for these processes are indefinite. METHOD: PAH was induced by a single intraperitoneal injection of monocrotaline (MCT) to rats. The right ventricle systolic pressure (RVSP), right ventricular hypertrophy index (RVHI), percentage of medial wall thickness (%MT), α-smooth muscle actin (α-SMA) staining, and Ki67 staining were performed to evaluate the development of PAH. The protein levels of FOXM1, phospho-focal adhesion kinase (p-FAK), FAK, and LC3B were determined by immunoblotting or immunohistochemistry. RESULTS: FOXM1 protein level and FAK activity were significantly increased in MCT-induced PAH rats, this was accompanied with the activation of autophagy. Pharmacological inhibition of FOXM1 or FAK suppressed MCT-induced autophagy activation, decreased RVSP, RVHI and %MT in MCT-induced PAH rats, and inhibited the proliferation of pulmonary arterial smooth muscle cells and pulmonary vessel muscularization in MCT-induced PAH rats. CONCLUSION: FOXM1 promotes the development of PAH by inducing FAK phosphorylation and subsequent activation of autophagy in MCT-treated rats.

Dapagliflozin reduces the vulnerability of rats with pulmonary arterial hypertension-induced right heart failure to ventricular arrhythmia by restoring calcium handling.

BACKGROUND: Malignant ventricular arrhythmia (VA) is a major contributor to sudden cardiac death (SCD) in patients with pulmonary arterial hypertension (PAH)-induced right heart failure (RHF). Recently, dapagliflozin (DAPA), a sodium/glucose cotransporter-2 inhibitor (SGLT2i), has been found to exhibit cardioprotective effects in patients with left ventricular systolic dysfunction. In this study, we examined the effects of DAPA on VA vulnerability in a rat model of PAH-induced RHF. METHODS: Rats randomly received monocrotaline (MCT, 60 mg/kg) or vehicle via a single intraperitoneal injection. A day later, MCT-injected rats were randomly treated with placebo, low-dose DAPA (1 mg/kg/day), or high-dose (3 mg/kg/day) DAPA orally for 35 days. Echocardiographic analysis, haemodynamic experiments, and histological assessments were subsequently performed to confirm the presence of PAH-induced RHF. Right ventricle (RV) expression of calcium (Ca2+) handling proteins were detected via Western blotting. RV expression of connexin 43 (Cx43) was determined via immunohistochemical staining. An optical mapping study was performed to assess the electrophysiological characteristics in isolated hearts. Cellular Ca2+ imaging from RV cardiomyocytes (RVCMs) was recorded using Fura-2 AM or Fluo-4 AM. RESULTS: High-dose DAPA treatment attenuated RV structural remodelling, improved RV function, alleviated Cx43 remodelling, increased the conduction velocity, restored the expression of key Ca2+ handling proteins, increased the threshold for Ca2+ and action potential duration (APD) alternans, decreased susceptibility to spatially discordant APD alternans and spontaneous Ca2+ events, promoted cellular Ca2+ handling, and reduced VA vulnerability in PAH-induced RHF rats. Low-dose DAPA treatment also showed antiarrhythmic effects in hearts with PAH-induced RHF, although with a lower level of efficacy. CONCLUSION: DAPA administration reduced VA vulnerability in rats with PAH-induced RHF by improving RVCM Ca2+ handling.

Silencing TUFM Inhibits Development of Monocrotaline-Induced Pulmonary Hypertension by Regulating Mitochondrial Autophagy via AMPK/mTOR Signal Pathway.

Pulmonary arterial hypertension (PAH) is an extremely malignant cardiovascular disease which mainly involves the uncontrollable proliferation of the pulmonary arterial smooth muscular cells (PASMCs). Recent studies have confirmed that mitochondria play an important role in the pathogenesis of pulmonary hypertension through sensing cell hypoxia, energy metabolism conversion, and apoptosis. As a mitochondrial membrane protein, TUFM has been regarded to be related to mitochondrial autophagy (mitophagy), apoptosis, and oxidative stress. Considering these factors are closely associated with the pathogenesis of PAH, we hypothesize that TUFM might play a role in the development of PAH. Our preliminary examination has showed TUFM mainly expressed in the PASMCs, and the subsequent test indicated an increased TUFM expression in the SMCs of pulmonary arteriole in monocrotaline- (MCT-) induced PAH rat model compared with the normal rat. The TUFM knockdown (Sh-TUFM) or overexpressed (OE-TUFM) rats were used to establish PAH by treating with MCT. A notable lower pulmonary arterial systolic pressure together with slightly morphological changes of pulmonary arteriole was observed in the Sh-TUFM group compared with the single MCT-induced PAH group. Increased levels of P62 and Bax and reduced LC3II/I, BECN1, and Bcl2 were detected in the Sh-TUFM group, while the expressions of these proteins in the OE-TUFM group were contrast to the results of the Sh-TUFM group. To elucidate the possible mechanism underlying biological effect of TUFM in PAH, PASMCs were treated with silence or overexpression of TUFM and then exposed to hypoxia condition. An obviously high levels of P62 and Bax along with a decreased LC3 II/I, BECN1, ULK1, Atg12, Atg13, and Bcl2 levels were noticed in cells with silence of TUFM. Moreover, the phosphorylated AMPK and mTOR which was well known in mitophagy modulating vary by the alternation of TUFM. These observations suggested that TUFM silence inhibits the development of MCT-induced PAH via AMPK/mTOR pathway.

HNRNPA2B1: RNA-Binding Protein That Orchestrates Smooth Muscle Cell Phenotype in Pulmonary Arterial Hypertension.

BACKGROUND: RNA-binding proteins are master orchestrators of gene expression regulation. They regulate hundreds of transcripts at once by recognizing specific motifs. Thus, characterizing RNA-binding proteins targets is critical to harvest their full therapeutic potential. However, such investigation has often been restricted to a few RNA-binding protein targets, limiting our understanding of their function. In cancer, the RNA-binding protein HNRNPA2B1 (heterogeneous nuclear ribonucleoprotein A2B1; A2B1) promotes the pro-proliferative/anti-apoptotic phenotype. The same phenotype in pulmonary arterial smooth muscle cells (PASMCs) is responsible for the development of pulmonary arterial hypertension (PAH). However, A2B1 function has never been investigated in PAH. METHOD: Through the integration of computational and experimental biology, the authors investigated the role of A2B1 in human PAH-PASMC. Bioinformatics and RNA sequencing allowed them to investigate the transcriptome-wide function of A2B1, and RNA immunoprecipitation and A2B1 silencing experiments allowed them to decipher the intricate molecular mechanism at play. In addition, they performed a preclinical trial in the monocrotaline-induced pulmonary hypertension rat model to investigate the relevance of A2B1 inhibition in mitigating pulmonary hypertension severity. RESULTS: They found that A2B1 expression and its nuclear localization are increased in human PAH-PASMC. Using bioinformatics, they identified 3 known motifs of A2B1 and all mRNAs carrying them. In PAH-PASMC, they demonstrated the complementary nonredundant function of A2B1 motifs because all motifs are implicated in different aspects of the cell cycle. In addition, they showed that in PAH-PASMC, A2B1 promotes the expression of its targets. A2B1 silencing in PAH-PASMC led to a decrease of all tested mRNAs carrying an A2B1 motif and a concomitant decrease in proliferation and resistance to apoptosis. Last, in vivo A2B1 inhibition in the lungs rescued pulmonary hypertension in rats. CONCLUSIONS: Through the integration of computational and experimental biology, the study revealed the role of A2B1 as a master orchestrator of the PAH-PASMC phenotype and its relevance as a therapeutic target in PAH.

Monocrotaline Toxicity Alters the Function of Hepatocyte Membrane Transporters in Rats.

Pyrrolizidine alkaloid monocrotaline (MCT) induces sinusoidal obstruction syndrome (SOS) in rats characterised by a sinusoidal congestive obstruction. Additionally, MCT administration decreases the biliary excretion of gadobenate dimeglumine (BOPTA), a hepatobiliary substrate used in clinical imaging. BOPTA crosses hepatocyte membranes through organic anion transporting polypeptides, multidrug-resistance-associated protein 2, and Mrp3/4 transporters, and a modified function of these transporters is likely to explain the decreased biliary excretion. This study compared BOPTA transport across hepatocytes in livers isolated from normal (Nl) rats and rats with intragastric administration of MCT. BOPTA hepatocyte influx clearance was similar in both groups, while biliary clearance and bile concentrations were much lower in MCT than in Nl livers. BOPTA efflux clearance back to the sinusoids compensated for the low biliary excretion, and hepatocyte concentrations remained similar in both groups. This SOS-associated changes of transporter functions might impact the pharmacokinetics of numerous drugs that use similar transporters to cross hepatocytes.

[Tanshinone IIA alleviates monocrotaline-induced pulmonary hypertension in rats through the PI3K/Akt-eNOS signaling pathway].

OBJECTIVE: To explore the therapeutic mechanism of tanshinone IIA in the treatment of pulmonary arterial hypertension (PAH) in rats. METHODS: A total of 100 male SD rats were randomized into 5 groups (n=20), and except for those in the control group with saline injection, all the rats were injected with monocrotaline (MCT) on the back of the neck to establish models of pulmonary hypertension. Two weeks after the injection, the rat models received intraperitoneal injections of tanshinone IIA (10 mg/kg), phosphatidylinositol 3 kinase (PI3K) inhibitor (1 mg/kg), both tanshinone IIA and PI3K inhibitor, or saline (model group) on a daily basis. After 2 weeks of treatment, HE staining and α-SMA immunofluorescence staining were used to evaluate the morphology of the pulmonary vessels of the rats. The phosphorylation levels of PI3K, protein kinase B (PKB/Akt) and endothelial nitric oxide synthase (eNOS) in the lung tissue were determined with Western blotting; the levels of eNOS and NO were measured using enzyme-linked immunosorbent assay (ELISA). RESULTS: The results of HE staining and α-SMA immunofluorescence staining showed that tanshinone IIA effectively inhibited MCT-induced pulmonary artery intimamedia thickening and muscularization of the pulmonary arterioles (P < 0.01). The results of Western blotting showed that treatment with tanshinone IIA significantly increased the phosphorylation levels of PI3K, Akt and eNOS proteins in the lung tissue of PAH rats; ELISA results showed that the levels of eNOS and NO were significantly decreased in the rat models after tanshinone IIA treatment (P < 0.01). CONCLUSION: Treatment with tanshinone IIA can improve MCT-induced pulmonary hypertension in rats through the PI3K/Akt-eNOS signaling pathway.

A potential model of systemic sclerosis with pulmonary hypertension induced by monocrotaline plus bleomycin.

OBJECTIVE: The lack of a well-established animal model limits the clarification of the detailed mechanisms of the pathogenesis of systemic sclerosis with pulmonary hypertension (SSc-PH) and the development of effective treatments for it. METHODS: In this study, New Zealand rabbits were injected with monocrotaline (MCT), bleomycin (BLM), and MCT plus BLM, respectively. Three and six weeks after the first injection, the mean pulmonary artery pressure (mPAP) was measured. Skin and lung samples were isolated and the histological changes were analyzed by hematoxylin and eosin staining or Masson's trichrome staining. RESULTS: All groups of rabbits showed an increased mean mPAP compared with the saline-injected rabbits. The high mPAP persisted until week six only in the MCT and MCT + BLM groups. Furthermore, persistent high Fulton's indices were found in the MCT and MCT + BLM groups, indicating that these treatments successfully induced right ventricular hypertrophy. The rabbits in the MCT + BLM group developed severe lung inflammation, as evidenced by a high level of neutrophil infiltration in the pulmonary interstitium. Importantly, pathological changes of the skin in the MCT + BLM group were observed, and further damage to the skin was caused by additional exposure to MCT plus BLM. Meanwhile, an excessive production of cytokines, including tumor necrosis factor alpha (TNF-α), and transforming growth factor beta 1 (TGF-ß1), were detected in the MCT + BLM group. CONCLUSION: These data indicate that SSc-PH induced by co-injection with MCT plus BLM shows persistent fibrosis and progressive PH, constituting a potential study model for SSc-PH.

Paeoniflorin attenuates monocrotaline-induced pulmonary arterial hypertension in rats by suppressing TAK1-MAPK/NF-κB pathways.

Pulmonary arterial hypertension (PAH) characterized by pulmonary vascular remodeling is a lethal disease. Paeoniflorin (PF) is a monoterpene glycoside with numerous beneficial functions, such as vasodilation, anti-inflammation and immunomodulation. This study aims to investigate the effects of PF on monocrotaline (MCT)-induced PAH rats. Our data showed that both prophylactic or therapeutic administration of PF alleviated MCT-induced increasing of right ventricular systolic pressure (RVSP), prevented right ventricle hypertrophy and pulmonary arterial remodeling, as well as inhibited inflammatory cell infiltration around pulmonary arteries. Meanwhile, PF blocked MCT-induced endothelial-mesenchymal transition (EndMT) as indicated by the restored expression of endothelial markers in lung. Moreover, PF inhibited MCT-induced down-regulation of bone morphogenetic protein receptor 2 (BMPR2) and suppressed MCT-induced phosphorylation of transforming growth factor-ß (TGFß) activated kinase 1 (TAK1) in vivo. In vitro studies indicated that PF prevented human pulmonary arterial smooth muscle cells (PASMCs) from platelet-derived growth factor-BB (PDGF-BB)-stimulated proliferation and migration. PF also partially reversed TGFß1, interleukin-1ß (IL-1ß) and tumor necrosis factor (TNF-α) co-stimulated endothelial-to-mesenchymal transition (EndMT) in cultured human pulmonary artery endothelial cells (HPAECs). Signaling pathway analysis demonstrated that the underlying mechanism might be associated with the inhibition of TAK1-MAPK/NF-κB pathways. Taken together, our results suggested that PF could be a potential drug for the treatment of PAH.

Neutralization of GDF15 Prevents Anorexia and Weight Loss in the Monocrotaline-Induced Cardiac Cachexia Rat Model.

Growth and differentiation factor 15 (GDF15) is a cytokine reported to cause anorexia and weight loss in animal models. Neutralization of GDF15 was efficacious in mitigating cachexia and improving survival in cachectic tumor models. Interestingly, elevated circulating GDF15 was reported in patients with pulmonary arterial hypertension and heart failure, but it is unclear whether GDF15 contributes to cachexia in these disease conditions. In this study, rats treated with monocrotaline (MCT) manifested a progressive decrease in body weight, food intake, and lean and fat mass concomitant with elevated circulating GDF15, as well as development of right-ventricular dysfunction. Cotreatment of GDF15 antibody mAb2 with MCT prevented MCT-induced anorexia and weight loss, as well as preserved lean and fat mass. These results indicate that elevated GDF15 by MCT is causal to anorexia and weight loss. GDF15 mAb2 is efficacious in mitigating MCT-induced cachexia in vivo. Furthermore, the results suggest GDF15 inhibition is a potential therapeutic approach to alleviate cardiac cachexia in patients.