DT-13 Ameliorates TNF-α-Induced Vascular Endothelial Hyperpermeability via Non-Muscle Myosin IIA and the Src/PI3K/Akt Signaling Pathway

Endothelial Cell Integrin α6 Regulates Vascular Remodeling Through the PI3K/Akt-eNOS-VEGFA Axis After Stroke

The angiogenic response is essential for the repair of ischemic brain tissue. Integrin α6 (Itga6) expression has been shown to increase under hypoxic conditions and is expressed exclusively in vascular structures; however, its role in post-ischemic angiogenesis remains poorly understood. In this study, we demonstrate that mice with endothelial cell-specific knockout of Itga6 exhibit reduced neovascularization, reduced pericyte coverage on microvessels, and accelerated breakdown of microvascular integrity in the peri-infarct area. In vitro, endothelial cells with ITGA6 knockdown display reduced proliferation, migration, and tube-formation. Mechanistically, we demonstrated that ITGA6 regulates post-stroke angiogenesis through the PI3K/Akt-eNOS-VEGFA axis. Importantly, the specific overexpression of Itga6 in endothelial cells significantly enhanced neovascularization and enhanced the integrity of microvessels, leading to improved functional recovery. Our results suggest that endothelial cell Itga6 plays a crucial role in key steps of post-stroke angiogenesis, and may represent a promising therapeutic target for promoting recovery after stroke.

Potential bidirectional regulatory effects of botanical drug metabolites on tumors and cardiovascular diseases based on the PI3K/Akt/mTOR pathway

Pharmacological interventions targeting the phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway are predominantly employed as anticancer therapies, yet they are frequently associated with significant cardiac toxicity. Additionally, the PI3K/Akt/mTOR pathway plays a crucial role in the treatment of cardiovascular diseases, highlighting its dual significance in both oncology and cardiology. Therefore, the PI3K/Akt/mTOR pathway has become an ideal signaling pathway for studying cardioprotection, anticancer effects, and their associated cardiac toxicity. Botanical drugs have emerged as a significant source for developing therapeutic agents with anticancer and cardioprotective effects, often exhibiting bidirectional protective properties. Consequently, this study investigates the bidirectional regulatory influence of botanical drug metabolites in oncology and cardiology via the PI3K/Akt/mTOR pathway. The research indicated that the PI3K/Akt/mTOR signaling pathway plays a critical regulatory role in the pathogenesis of both tumors and cardiovascular diseases. The botanical drug metabolites Ruscogenin, Sulforaphane, Naringenin, Kaempferol, Poncirin, and Puerarin can improve cancer by inhibiting the phosphorylation levels within the PI3K/Akt/mTOR signaling cascade. Moreover, they also provide cardioprotective effects in cardiac injury conditions by activating the phosphorylation levels of the PI3K/Akt/mTOR pathway. Therefore, the phosphorylation dynamics of key components in the PI3K/Akt/mTOR pathway, particularly the phosphorylation of Akt, along with the functional implications of different phosphorylation sites, may offer new therapeutic strategies and insights for cancer treatment and the mitigation of cardiotoxicity associated with cancer therapies.

Distinguishing host responses, extensive viral dissemination and long-term viral RNA persistence in domestic sheep experimentally infected with Crimean-Congo haemorrhagic fever virus Kosovo Hoti

Crimean-Congo haemorrhagic fever orthonairovirus (CCHFV) is a tick-borne, risk group 4 pathogen that often causes a severe haemorrhagic disease in humans (CCHF) with high case fatality rates. The virus is believed to be maintained in a tick-vertebrate-tick ecological cycle involving numerous wild and domestic animal species; however the biology of CCHFV infection in these animals remains poorly understood. Here, we experimentally infect domestic sheep with CCHFV Kosovo Hoti, a clinical isolate representing high pathogenicity to humans and increasingly utilized in current research. In the absence of prominent clinical signs, the infection leads to an acute viremia and coinciding viral shedding, fever and markers for potential impairment in liver and kidney functions. A number of host responses distinguish the subclinical infection in sheep versus fatal infection in humans. These include an early reduction of neutrophil recruitment and its chemoattractant, IL-8, in the blood stream of infected sheep, whereas neutrophil infiltration and elevated IL-8 are features of fatal CCHFV infections reported in immunodeficient mice and humans. Several inflammatory cytokines that correlate with poor disease outcomes in humans and have potential to cause vascular dysfunction, a primary hallmark of severe CCHF, are down-regulated or restricted from increasing in sheep. Of particular interest, the detection of CCHFV RNA (including full-length genome) in a variety of sheep tissues long after the acute phase of infection indicates a widespread viral dissemination in the host and suggests a potentially long-term persisting impact of CCHFV infection. These findings reveal previously unrecognized aspects of CCHFV biology in animals.

In vitro analysis of VEGF-mediated endothelial permeability and the potential therapeutic role of Anti-VEGF in severe dengue

Background

Vascular endothelial growth factor (VEGF) is one of the proteins involved in dengue immunopathogenesis. It is overexpressed in severe dengue and contributes to vascular permeability and plasma leakage. In this study, we investigated the effects of VEGF and anti-VEGF treatments on endothelial cells in vitro, to assess the potential use of anti-VEGF antibodies in managing severe dengue.

Methods

Human pulmonary microvascular endothelial cells were treated with VEGF and a VEGF/anti-VEGF combination. The effects of the treatments were studied using an endothelial permeability assay and microarray gene expression profiling. In the permeability assay, the fluorescein isothiocyanate (FITC)-dextran fluorescence signal across the endothelial monolayer was recorded, and the cells were stained with PECAM-1 to detect gap formation. RNA was extracted from treated cells for microarray gene profiling and analysis. The results were analyzed for differentially expressed genes (DEGs) and gene enrichment analysis. The DEGs were subjected to STRING to construct the protein-protein interaction network and then Cytoscape to identify the hub genes.

Results

VEGF-treated endothelial cells showed greater movement of FITC-dextran across the monolayer than VEGF/anti-VEGF-treated cells. There were 111 DEGs for VEGF-treated cells and 118 DEGs for VEGF/anti-VEGF-treated cells. The genes upregulated in VEGF-treated cells were enriched in inflammatory responses and regulation of the endothelial barrier, nitric oxide synthesis, angiogenesis, and the nucleotide-binding oligomerization domain-like receptor signaling pathway. Top 10 hub genes were identified from the DEGs.

Conclusions

VEGF treatment increased permeability across endothelial cells, while anti-VEGF reduced this leakage. Analysis of VEGF-treated endothelial cells identified hub genes implicated in severe dengue. The top 10 hub genes were TNF, IL1B, IL6, CCL2, PTGS2, ICAM1, CXCL2, CXCL1, CSF2, and TLR2. The results of this study show that using anti-VEGF antibodies to neutralize VEGF may be a promising therapy to prevent the progression of dengue to severe dengue.

Ruxolitinib attenuates microglial inflammatory response by inhibiting NF-κB/MAPK signaling pathway

Neuroinflammation is involved in the physiological and pathological processes of numerous neurological diseases, and its inhibition seems to be a promising therapeutic direction for these diseases. Ruxolitinib is a classical Janus kinase (JAK) inhibitor that is oral, highly potent and bioavailable, which has recently gained approval from the US Food and Drug Administration (FDA) for the treatment of inflammatory disorders. The potential inhibitory effect of ruxolitinib on neuroinflammation has not been fully studied. In the lipopolysaccharide (LPS) induced neuroinflammatory cell model, we observed that ruxolitinib reduced the levels of IL-1β, IL-6 and tumor necrosis factor-α (TNF-α) expression, and neuroinflammation by inhibiting the Mitogen-Activated Protein Kinase/Nuclear factor-κ B (MAPK/NF-κB) signaling pathway. Similarly, mice injected intracerebroventricular with ruxolitinib exhibited significantly reduced LPS-stimulated activation of microglia and astrocytes, and expression of proinflammatory cytokine IL-1β, TNF-α and IL-6. These results demonstrate that ruxolitinib attenuates the neuroinflammatory responses both in vivo and in vitro, at least in part by inhibiting MAPK/NF-κB signaling pathway. Our findings suggest that ruxolitinib may serve as a potential drug for the treatment of microglia-mediated neuroinflammation.

MYH9: A key protein involved in tumor progression and virus-related diseases

The myosin heavy chain 9 (MYH9) gene encodes the heavy chain of non-muscle myosin IIA (NMIIA), which belongs to the myosin II subfamily of actin-based molecular motors. Previous studies have demonstrated that abnormal expression and mutations of MYH9 were correlated with MYH9-related diseases and tumors. Furthermore, earlier investigations identified MYH9 as a tumor suppressor. However, subsequent research revealed that MYH9 promoted tumorigenesis, progression and chemoradiotherapy resistance. Note-worthily, MYH9 has also been linked to viral infections, like severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Epstein-Barr virus, and hepatitis B virus, as a receptor or co-receptor. In addition, MYH9 promotes the development of hepatocellular carcinoma by interacting with the hepatitis B virus-encoding X protein. Finally, various findings highlighted the role of MYH9 in the development of these illnesses, especially in tumors. This review summarizes the involvement of the MYH9-regulated signaling network in tumors and virus-related diseases and presents possible drug interventions on MYH9, providing insights for the use of MYH9 as a therapeutic target for tumors and virus-mediated diseases.

Ruscogenin ameliorates dasatinib-induced intestinal barrier dysfunction via ErbB4/YAP and ROCK/MLC pathways

Dasatinib is effective in the treatment of chronic and acute myeloid leukemia, which could cause the side effect of gastrointestinal bleeding by overdose or longtime use. Ruscogenin (RUS) from the traditional Chinese medicine Ophiopogon japonicas could protect endothelial microvascular barrier function. In this study, the therapeutic effect and underlying mechanisms of RUS were investigated on intestinal barrier dysfunction induced by dasatinib. Male C57BL/6 J mice were given three doses of dasatinib (70, 140, 210 mg/kg, ig) and RUS (3, 10, 30 μg/kg, ip) to explore the effect of dasatinib on intestinal barrier and the intervention of RUS. It was proved that dasatinib could reduce intestinal blood flow, inhibit phosphorylation of EGFR family member v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 4 (ErbB4)/YES-associated protein (YAP) and activation of Rho-associated coiled coil-containing protein kinase (ROCK)/phosphorylation of (myosin light chain) MLC. RUS could significantly increase intestinal blood flow, improve intestinal injury, reduce Evans blue leakage and serum content of FITC-dextran 4 kDa, and increase the expression of connexin (ZO-1, Occludin and VE-cadherin). Meanwhile, the in vitro effect of RUS (0.01, 0.1, 1 μM) on the dysfunction of the endothelial barrier was observed in dasatinib (150 nM)-pretreated HUVECs. The results showed that RUS suppressed dasatinib-induced the leakage of Evans blue, and degradation of F-actin and connexin. Furthermore, RUS could significantly increase the phosphorylation of ErbB4 at Tyr1284 site and YAP at Ser397 site, and inhibit ROCK expression and phosphorylation of MLC at Ser19 site in vivo and in vitro. In conclusion, the present research proved that RUS could suppress the side effects of dasatinib-induced intestinal barrier dysfunction by regulating ErbB4/YAP and ROCK/MLC pathways.

Siponimod As a Novel Inhibitor of Retinal Angiogenesis: In Vitro and In Vivo Evidence of Therapeutic Efficacy

Sphingosine-1-phosphate (S1P) receptors control endothelial cell proliferation, migration, and survival. Evidence of the ability of S1P receptor modulators to influence multiple endothelial cell functions suggests their potential use for antiangiogenic effect. The main purpose of our study was to investigate the potential of siponimod for the inhibition of ocular angiogenesis in vitro and in vivo. We investigated the effects of siponimod on the metabolic activity (thiazolyl blue tetrazolium bromide assay), cell toxicity (lactate dehydrogenase release), basal proliferation and growth factor-induced proliferation (bromodeoxyuridine assay), and migration (transwell migration assay) of human umbilical vein endothelial cells (HUVEC) and retinal microvascular endothelial cells (HRMEC). The effects of siponimod on HRMEC monolayer integrity, barrier function under basal conditions, and tumor necrosis factor alpha (TNF-α)-induced disruption were assessed using the transendothelial electrical resistance and fluorescein isothiocyanate-dextran permeability assays. Siponimod's effect on TNF-α-induced distribution of barrier proteins in HRMEC was investigated using immunofluorescence. Finally, the effect of siponimod on ocular neovascularization in vivo was assessed using suture-induced corneal neovascularization in albino rabbits. Our results show that siponimod did not affect endothelial cell proliferation or metabolic activity but significantly inhibited endothelial cell migration, increased HRMEC barrier integrity, and reduced TNF-α-induced barrier disruption. Siponimod also protected against TNF-α-induced disruption of claudin-5, zonula occludens-1, and vascular endothelial-cadherin in HRMEC. These actions are mainly mediated by sphingosine-1-phosphate receptor 1 modulation. Finally, siponimod prevented the progression of suture-induced corneal neovascularization in albino rabbits. In conclusion, the effects of siponimod on various processes known to be involved in angiogenesis support its therapeutic potential in disorders associated with ocular neovascularization. SIGNIFICANCE STATEMENT: Siponimod is an extensively characterized sphingosine-1-phosphate receptor modulator already approved for the treatment of multiple sclerosis. It inhibited retinal endothelial cell migration, potentiated endothelial barrier function, protected against tumor necrosis factor alpha-induced barrier disruption, and also inhibited suture-induced corneal neovascularization in rabbits. These results support its use for a novel therapeutic indication in the management of ocular neovascular diseases.

Aucubin supplementation alleviate diabetes induced-disruption of blood-testis barrier and testicular damage via stabilizing cell junction integrity

Disruption of blood-testis barrier (BTB) was a crucial pathological feature of diabetes induced-testicular injury at early phase. Aucubin (AU), a main active component in Eucommiae Cortex, has drawn attention for its benefits against male reproductive system disease. The current study was aimed at investigating the protective role of AU and exploring the underlying mechanism in diabetic model. A murine model of type 2 diabetes mellitus (T2DM) was induced by high-fat diet (HFD) combined with streptozocin (STZ). Testicular weight index and morphology, sperm quality, integrity of BTB and protein levels were analyzed. The underlying mechanism of the protective effect of AU was further explored in Sertoli cells (SCs) cultured with high glucose (HG). Our results showed AU inhibited testicular structural destruction, restored disruption of BTB and improved abnormal spermatogenic function in diabetic mice. Consistent with in vivo results, HG induced decreased transcellular resistance and increased permeability in SCs monolayers, while AU exposure reverses this trend. Meanwhile, reduced expression of Zonula occludin-1(ZO-1) and Connexin43(Cx43) in testicular tissue diabetic mice and HG-induced SCs was prominently reversed via AU treatment. Mechanistic studies suggested a high affinity interaction between AU and c-Src protein was identified based on molecular docking, and the activation of c-Src was significantly inhibited in AU treatment. Furthermore, AU significantly increased the expression of Cx43 and ZO-1 proteins HG-induced SCs, which can be further enhanced in gene-silenced c-Src cells to some extent. Our results suggested that AU ameliorated disruption of BTB and spermatogenesis dysfunction in diabetic mice via inactivating c-Src to stabilize cell junction integrity.

Fumonisin B1 Inhibits Cell Proliferation and Decreases Barrier Function of Swine Umbilical Vein Endothelial Cells

The fumonisins are a group of common mycotoxins found around the world that mainly contaminate maize. As environmental toxins, they pose a threat to human and animal health. Fumonisin B₁ (FB₁) is the most widely distributed and the most toxic. FB₁ can cause pulmonary edema in pigs. However, the current toxicity mechanism of fumonisins is still in the exploratory stage, which may be related to sphingolipid metabolism. Our study is designed to investigate the effect of FB₁ on the cell proliferation and barrier function of swine umbilical vein endothelial cells (SUVECs). We show that FB₁ can inhibit the cell viability of SUVECs. FB₁ prevents cells from entering the S phase from the G1 phase by regulating the expression of the cell cycle-related genes cyclin B1, cyclin D1, cyclin E1, Cdc25c, and the cyclin-dependent kinase-4 (CDK-4). This results in an inhibition of cell proliferation. In addition, FB₁ can also change the cell morphology, increase paracellular permeability, destroy tight junctions and the cytoskeleton, and reduce the expression of tight junction-related genes claudin 1, occludin, and ZO-1. This indicates that FB₁ can cause cell barrier dysfunction of SUVECs and promote the weakening or even destruction of the connections between endothelial cells. In turn, this leads to increased blood vessel permeability and promotes exudation. Our findings suggest that FB₁ induces toxicity in SUVECs by affecting cell proliferation and disrupting the barrier function.

Quantum dots combined with a fluorescence-linked immunosorbent assay for detecting the metabolic balance of DT-13 excretion in rats

Saponin monomer 13 of the dwarf lilyturf tuber (DT-13) is a steroidal saponin component isolated from the tuber of Liriope muscari (Decne.) Bailey that exhibits multiple pharmacological activities. We used a liquid chromatography-tandem mass spectrometry method and MetaboLynx XS software to investigate the metabolites of DT-13 in vivo and obtained potential metabolites and changes in functional groups during the formation of metabolites from the substrate. The main metabolites obtained had the ruscogenin (RUS) backbone structure. We also report a competitive fluorescence-linked immunosorbent assay (FLISA) based on monoclonal antibodies (MABS) conjugated with quantum dots (QDs) for rapid and sensitive quantitative analysis of DT-13 and its metabolite levels in biological samples. Using this method, the DT-13 levels detected in rat urine and feces displayed a good linear relationship within the corresponding linear ranges. The DT-13 recovery rate ranged from 85.28 to 101.40%, with a relative standard deviation of 2.96-9.26%. The method was successfully applied to study the distribution of DT-13 excretion in rats after oral administration. DT-13 was primarily excreted in the urine after metabolism. This study provides a new tool for pharmacokinetic studies of DT-13 and other active substances for which the analysis efficacy does not match the bioavailability or that are difficult to study using isotope labeling.

Unfractionated heparin attenuates endothelial barrier dysfunction via the phosphatidylinositol-3 kinase/serine/threonine kinase/nuclear factor kappa-B pathway

Background

Vascular endothelial dysfunction is considered a key pathophysiologic process for the development of acute lung injury. In this study, we aimed at investigating the effects of unfractionated heparin (UFH) on the lipopolysaccharide (LPS)-induced changes of vascular endothelial-cadherin (VE-cadherin) and the potential underlying mechanisms.

Methods

Male C57BL/6 J mice were randomized into three groups: vehicle, LPS, and LPS + UFH groups. Intraperitoneal injection of 30 mg/kg LPS was used to induce sepsis. Mice in the LPS + UFH group received subcutaneous injection of 8 U UFH 0.5 h before LPS injection. The lung tissue of the mice was collected for assessing lung injury by measuring the lung wet/dry (W/D) weight ratio and observing histological changes. Human pulmonary microvascular endothelial cells (HPMECs) were cultured and used to analyze the effects of UFH on LPS- or tumor necrosis factor-alpha (TNF-α)-induced vascular hyperpermeability, membrane expression of VE-cadherin, p120-catenin, and phosphorylated myosin light chain (p-MLC), and F-actin remodeling, and on the LPS-induced activation of the phosphatidylinositol-3 kinase (PI3K)/serine/threonine kinase (Akt)/nuclear factor kappa-B (NF-κB) signaling pathway.

Results

In vivo, UFH pretreatment significantly attenuated LPS-induced pulmonary histopathological changes (neutrophil infiltration and erythrocyte effusion, alveolus pulmonis collapse, and thicker septum), decreased the lung W/D, and increased protein concentration (LPS vs. LPS + UFH: 0.57 ± 0.04 vs. 0.32 ± 0.04 mg/mL, P = 0.0092), total cell count (LPS vs. LPS + UFH: 9.57 ± 1.23 vs. 3.65 ± 0.78 × 10⁵/mL, P = 0.0155), polymorphonuclear neutrophil percentage (LPS vs. LPS + UFH: 88.05% ± 2.88% vs. 22.20% ± 3.92%, P = 0.0002), and TNF-α (460.33 ± 23.48 vs. 189.33 ± 14.19 pg/mL, P = 0.0006) in the bronchoalveolar lavage fluid. In vitro, UFH pre-treatment prevented the LPS-induced decrease in the membrane expression of VE-cadherin (LPS vs. LPS + UFH: 0.368 ± 0.044 vs. 0.716 ± 0.064, P = 0.0114) and p120-catenin (LPS vs. LPS + UFH: 0.208 ± 0.018 vs. 0.924 ± 0.092, P = 0.0016), and the LPS-induced increase in the expression of p-MLC (LPS vs. LPS + UFH: 0.972 ± 0.092 vs. 0.293 ± 0.025, P = 0.0021). Furthermore, UFH attenuated LPS- and TNF-α-induced hyperpermeability of HPMECs (LPS vs. LPS + UFH: 8.90 ± 0.66 vs. 15.84 ± 1.09 Ω·cm², P = 0.0056; TNF-α vs. TNF-α + UFH: 11.28 ± 0.64 vs. 18.15 ± 0.98 Ω·cm², P = 0.0042) and F-actin remodeling (LPS vs. LPS + UFH: 56.25 ± 1.51 vs. 39.70 ± 1.98, P = 0.0027; TNF-α vs. TNF-α + UFH: 55.42 ± 1.42 vs. 36.51 ± 1.20, P = 0.0005) in vitro. Additionally, UFH decreased the phosphorylation of Akt (LPS vs. LPS + UFH: 0.977 ± 0.081 vs. 0.466 ± 0.035, P = 0.0045) and I kappa B Kinase (IKK) (LPS vs. LPS + UFH: 1.023 ± 0.070 vs. 0.578 ± 0.044, P = 0.0060), and the nuclear translocation of NF-κB (LPS vs. LPS + UFH: 1.003 ± 0.077 vs. 0.503 ± 0.065, P = 0.0078) in HPMECs, which was similar to the effect of the PI3K inhibitor, wortmannin.

Conclusions

The protective effect of UFH against LPS-induced pulmonary endothelial barrier dysfunction involves VE-cadherin stabilization and PI3K/Akt/NF-κB signaling.

Ophiopogon Saponin C1 Inhibits Lung Tumors by Stabilizing Endothelium Permeability via Inhibition of PKCδ

As the most frequent cause of cancer-related death worldwide, lung cancer is closely related to inflammation. The interaction between tumor cells and inflammatory cells promotes tumor development and metastasis. During tumor development, vascular endothelial cells form the most important barrier to prevent tumor cell migration to the blood and tissue. Increased vascular permeability provides favorable conditions for the migration of tumor cells, and endothelial tight junctions are an important component of the vascular barrier. Protein kinase C δ is involved in the occurrence of non-small cell lung cancer and regulates vascular permeability and tight junction protein expression. Src kinase was reported to play an important role in TNF-α-induced endothelial inflammation. Ophiopogon Saponin C1 is a new chemical compound isolated from Liriope muscari, but its pharmacological activities have not been fully elucidated. Therefore, we tested the protective effects of C1 on endothelial permeability in a model of TNF-α-induced endothelial inflammation by transendothelial electrical resistance and sodium fluorescein assays and verified these results in a nude mouse model of experimental pulmonary adenocarcinoma metastasis. We further elucidated the mechanism of C1, which was based on the PKCδ and Src proteins, by Western blotting. C1 can inhibit lung cancer in vivo, regulate the level of plasma inflammation in tumor-bearing mice, and protect the pulmonary vascular barrier against injury induced by cancer. It was investigated the expression and distribution of the TJ index protein ZO-1 in mouse vascular endothelium and HUVECs and found that C1 could inhibit the degradation and breakage of the ZO-1 protein. Related signaling experiments confirmed that C1 can inhibit TNF-α and activation of PKCδ and Src kinase. This study laid the foundation for further analysis of new drugs with clear mechanisms and independent intellectual property rights of traditional Chinese medicines.

Endothelial tight junctions and their regulatory signaling pathways in vascular homeostasis and disease

Endothelial tight junctions (TJs) regulate the transport of water, ions, and molecules through the paracellular pathway, serving as an important barrier in blood vessels and maintaining vascular homeostasis. In endothelial cells (ECs), TJs are highly dynamic structures that respond to multiple external stimuli and pathological conditions. Alterations in the expression, distribution, and structure of endothelial TJs may lead to many related vascular diseases and pathologies. In this review, we provide an overview of the assessment methods used to evaluate endothelial TJ barrier function both in vitro and in vivo and describe the composition of endothelial TJs in diverse vascular systems and ECs. More importantly, the direct phosphorylation and dephosphorylation of TJ proteins by intracellular kinases and phosphatases, as well as the signaling pathways involved in the regulation of TJs, including and the protein kinase C (PKC), PKA, PKG, Ras homolog gene family member A (RhoA), mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K)/Akt, and Wnt/β-catenin pathways, are discussed. With great advances in this area, targeting endothelial TJs may provide novel treatment for TJ-related vascular pathologies.

Inhibition of Src activation reverses pulmonary vascular remodeling in experimental pulmonary arterial hypertension via Akt/mTOR/HIF-1<alpha> signaling pathway

Pulmonary arterial hypertension (PAH) is a diffuse pulmonary microvascular remodeling disease accompanied by malignant proliferation of pulmonary artery smooth muscle cells (PASMCs), which causes persistent pulmonary artery pressure elevation, right ventricular hypertrophy (RVH) and death. However, current therapies targeting pulmonary vascular remodeling and RVH remain poorly effective in reversing PAH. Overactivation of the protein tyrosine kinase Src plays an important role in tumor cell growth, proliferation and invasion; we thus hypothesized that inhibitors targeting Src activation could reverse experimental PAH. We demonstrated that Src was markedly activated in hypoxia-stimulated PASMCs from donors and PASMCs isolated from PAH patients. We investigated the effects of the Src-selective inhibitor 1-(1,1-dimethylethyl)-1-(4-methylphenyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine (PP1) and berberine (BBR) on PAH-PASMC proliferation and migration by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine (EdU) and wound-healing assays. Our in vitro results showed that inhibition of Src (Tyr416) phosphorylation repressed PAH-PASMC proliferation and migration by inhibiting hypoxia-inducible factor-1α (HIF-1α) expression through Akt/mTOR signal pathway. In vivo, PP1 and BBR significantly alleviated distal pulmonary vascular remodeling and decreased right ventricular systolic pressure (RVSP) and RVH in Sugen (SU) 5416/hypoxia (SU-PAH) mice. These findings demonstrate that pharmacological (PP1 or BBR) inhibition of Src activation could be a novel means of treating severe pulmonary vascular remodeling and RVH in PAH patients.