Halofuginone, a promising drug for treatment of pulmonary hypertension

Dichroa febrifuga Lour.: A review of its botany, traditional use, phytochemistry, pharmacological activities, toxicology, and progress in reducing toxicity

ETHNOPHARMACOLOGICAL RELEVANCE

Dichroa febrifuga Lour., a toxic but extensively used traditional Chinese medicine with a remarkable effect, is commonly called "Changshan" in China. It has been used to treat malaria and many other parasitic diseases.

AIM OF THE REVIEW

The study aims to provide a current overview of the progress in the research on traditional use, phytochemistry, pharmacological activities, toxicology, and methods of toxicity reduction of D. febrifuga. Additionally, further research directions and development prospects for the plant were put forward.

MATERIALS AND METHODS

The article uses "Dichroa febrifuga Lour." "D. febrifuga" as the keyword and all relevant information on D. febrifuga was collected from electronic searches (Elsevier, PubMed, ACS, CNKI, Google Scholar, and Baidu Scholar), doctoral and master's dissertations and classic books about Chinese herbs.

RESULTS

30 chemical compounds, including alkaloids, terpenoids, flavonoids and other kinds, were isolated and identified from D. febrifuga. Modern pharmacological studies have shown that these components have a variety of pharmacological activities, including anti-malarial activities, anti-inflammatory activities, anti-tumor activities, anti-parasitic activities and anti-oomycete activities. Meanwhile, alkaloids, as the material basis of its efficacy, are also the source of its toxicity. It can cause multiple organ damage, including liver, kidney and heart, and cause adverse reactions such as nausea and vomiting, abdominal pain and diarrhea. In the current study, the toxicity can be reduced by modifying the structure of the compound, processing and changing the dosage forms.

CONCLUSIONS

There are few studies on the chemical constituents of D. febrifuga, so the components and their structure characterization contained in it can become the focus of future research. In view of the toxicity of D. febrifuga, there are many methods to reduce it, but the safety and rationality of these methods need further study.

miR-210-5p Promotes Pulmonary Hypertension by Blocking ATP2A2

AIM

Aberrant expression of ATPase sarcoplasmic/endoplasmic retic Ca2+ transporting 2 (ATP2A2) has attracted attention for its pathophysiologic role in pulmonary hypertension (PH). Several miRNAs, including miR-210-5p, have also been reported to be pathogenic factors in PH, but their exact mechanisms remain unknown. This study aimed to elucidate the potential mechanisms of miR-210-5p and ATP2A2 in MCT-induced PH.

METHODS

Eighteen Sprague-Dawley rats were randomly divided into two groups-monoclonal (MCT) group and control group-and then administered MCT (60 mg/kg) and saline, respectively. mPAP, PVR, RVHI, WT%, and WA% were significantly increased in PH rats after 3 weeks, confirming that the modeling of PH rats was successful. Subsequently, we determined the expression of ATP2A2 and miR-210-5p in lung tissues using WB and qRT-PCR methods. We established an in vitro model using BMP4 and TGF-β1 treatment of pulmonary artery smooth muscle cells (PASMCs) and examined the expression of ATP2A2 and miR-210-5p using the same method. To further elucidate the regulatory relationship between ATP2A2 and miR-210-5p, we altered the expression level of miR-210-5p and detected the corresponding changes in ATP2A2 levels. In addition, we demonstrated the relationship by dual luciferase experiments. Finally, the effect of silencing ATP2A2 could be confirmed by the level of cell membrane Ca2+ in PAMSCs.

RESULTS

Up-regulation of miR-210-5p and down-regulation of ATP2A2 were observed in the MCT group compared with the control group, which was confirmed in the in vitro model. In addition, elevated miR-210-5p expression decreased the level of ATP2A2 while increasing the proliferation of PASMCs, and the results of the dual luciferase assay further confirmed that ATP2A2 is a downstream target of miR-210-5p. Additionally, silencing ATP2A2 resulted in increased cytoplasmic Ca2+ levels in PAMSCs.

CONCLUSION

In MCT-induced PH, miR-210-5p promotes pulmonary vascular remodeling by inhibiting ATP2A2.

Preventive effect of LCZ696 on hypoxic pulmonary hypertension in rats via regulating the PI3K/AKT signaling pathway

Hypoxic pulmonary hypertension (HPH) is a devastating disease worldwide; however, effective therapeutic drugs are lacking. This study investigated the effects and underlying mechanisms of LCZ696 treatment on hypoxia-induced pulmonary hypertension. Male Sprague-Dawley (SD) rats were kept in a hypobaric chamber with an oxygen concentration of 5% for 4 weeks. Rats were treated with either LCZ696 (18 mg/kg, 36 mg/kg, and 72 mg/kg) or sildenafil. The mean pulmonary artery pressure (mPAP), right ventricle hypertrophy index (RVHI), and lung system index were measured. Hematoxylin-eosin (HE) staining, Masson staining, and immunofluorescence staining were used for histological analysis. Enzyme linked immunosorbent assay (ELISA) kits were used to determine the concentrations of inflammatory and hypoxia-related factors. Western blotting was used to examine the expression of apoptotic and PI3K/AKT signaling pathway proteins in rat lung tissue. Hypoxia increased mPAP, RVHI, and lung system index and induced pulmonary vascular remodeling, pulmonary arteriomyosis, and pulmonary artery fibrosis. LCZ696 treatment reduced the increase in mPAP, RVHI, and the lung system index and ameliorated the induced pathological changes. Hypoxia upregulated expression of NF-kB, TNF-α, IL-6, HIF-1α, and Vascular endothelial growth factor (VEGF), decreased the ratio of Bax/Bcl-2, and activated the PI3K/AKT signaling pathway in lung tissue, and these effects were partially reversed by treatment with LCZ696. These results demonstrated that LCZ696 can ameliorate hypoxia-induced HPH by suppressing apoptosis, inhibiting the inflammatory response, and inhibiting the PI3K/AKT signaling pathway. It provides a reference for clinical rational drug use and lays a foundation for the study of HPH therapeutic drugs.

Phytochemicals targeting glycolysis in colorectal cancer therapy: effects and mechanisms of action

Colorectal cancer (CRC) is the third most common malignant tumor in the world, and it is prone to recurrence and metastasis during treatment. Aerobic glycolysis is one of the main characteristics of tumor cell metabolism in CRC. Tumor cells rely on glycolysis to rapidly consume glucose and to obtain more lactate and intermediate macromolecular products so as to maintain growth and proliferation. The regulation of the CRC glycolysis pathway is closely associated with several signal transduction pathways and transcription factors including phosphatidylinositol 3-kinases/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR), adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), hypoxia-inducible factor-1 (HIF-1), myc, and p53. Targeting the glycolytic pathway has become one of the key research aspects in CRC therapy. Many phytochemicals were shown to exert anti-CRC activity by targeting the glycolytic pathway. Here, we review the effects and mechanisms of phytochemicals on CRC glycolytic pathways, providing a new method of drug development.

Halofuginone inhibits cell proliferation and AKT/mTORC1 signaling in uterine leiomyoma cells

The present study aimed to explore the effects of antifibrotic agent halofuginone on uterine leiomyomas (ULs) cells. The survival of the uterine smooth muscle (UtSMC) cells and UL ELT3 cells were measured. Flow cytometry was used to assess the cell cycle distribution and apoptosis. Effects of halofuginone on the state of AKT/mTOR pathway were evaluated. Xenograft animal model was applied to explore the effects of halofuginone in vivo. Halofuginone inhibited the proliferation of ELT3 cells dose-dependently without obvious influence on UtSMC cells. Halofuginone suppressed cell cycle progression and promoted apoptosis of ELT3 cells dose-dependently. Also, p-AKT/AKT and p-p70S6/p70S6 were significantly lowered after treatment with 20 nM halofuginone. Additionally, halofuginone reduced ELT3 tumor growth in xenograft tumor animal model. The present study illustrates that halofuginone inhibits cell proliferation of ULs with low side effects on normal smooth muscle cells, and AKT/mTOR signaling pathway was inactivated meanwhile.

Puerarin-V prevents the progression of hypoxia- and monocrotaline-induced pulmonary hypertension in rodent models

Pulmonary hypertension (PH) is a cardiopulmonary disease characterized by a progressive increase in pulmonary vascular resistance. One of the initial pathogenic factors of PH is pulmonary arterial remodeling under various stimuli. Current marketed drugs against PH mainly relieve symptoms without significant improvement in overall prognosis. Discovering and developing new therapeutic drugs that interfere with vascular remodeling is in urgent need. Puerarin is an isoflavone compound extracted from the root of Kudzu vine, which is widely used in the treatment of cardiovascular diseases. In the present study, we evaluated the efficacy of puerarin in the treatment of experimental PH. PH was induced in rats by a single injection of MCT (50 mg/kg, sc), and in mice by exposure to hypoxia (10% O2) for 14 days. After MCT injection the rats were administered puerarin (10, 30, 100 mg · kg-1 · d-1, i.g.) for 28 days, whereas hypoxia-treated mice were pre-administered puerarin (60 mg · kg-1 · d-1, i.g.) for 7 days. We showed that puerarin administration exerted significant protective effects in both experimental PH rodent models, evidenced by significantly reduced right ventricular systolic pressure (RVSP) and lung injury, improved pulmonary artery blood flow as well as pulmonary vasodilation and contraction function, inhibited inflammatory responses in lung tissues, improved resistance to apoptosis and abnormal proliferation in lung tissues, attenuated right ventricular injury and remodeling, and maintained normal function of the right ventricle. We revealed that MCT and hypoxia treatment significantly downregulated BMPR2/Smad signaling in the lung tissues and PPARγ/PI3K/Akt signaling in the lung tissues and right ventricles, which were restored by puerarin administration. In addition, we showed that a novel crystal type V (Puer-V) exerted better therapeutic effects than the crude form of puerarin (Puer). Furthermore, Puer-V was more efficient than bosentan (a positive control drug) in alleviating the abnormal structural changes and dysfunction of lung tissues and right ventricles. In conclusion, this study provides experimental evidence for developing Puer-V as a novel therapeutic drug to treat PH.

Exosomes: A novel insight into traditional Chinese medicine

Exosomes are small extracellular vesicles and play an essential role in the mediation of intercellular communication both in health and disease. Traditional Chinese medicine (TCM) has historically been used to maintain human health and treat various diseases up till today. The interplay between exosomes and TCM has attracted researchers’ growing attention. By integrating the available evidence, TCM formulas and compounds isolated from TCM as exosome modulators have beneficial effects on multiple disorders, such as tumors, kidney diseases, and hepatic disease, which may associate with inhibiting cells proliferation, anti-inflammation, anti-oxidation, and attenuating fibrosis. Exosomes, a natural delivery system, are essential in delivering compounds isolated from TCM to target cells or tissues. Moreover, exosomes may be the potential biomarkers for TCM syndromes, providing strategies for TCM treatment. These findings may provide a novel insight into TCM from exosomes and serve as evidence for better understanding and development of TCM.

Mechanistic and therapeutic perspectives of baicalin and baicalein on pulmonary hypertension: A comprehensive review

Pulmonary hypertension (PH) is a chronic and fatal disease, for which new therapeutic drugs and approaches are needed urgently. Baicalein and baicalin, the active compounds of the traditional Chinese medicine, Scutellaria baicalensis Georgi, exhibit a wide range of pharmacological activities. Numerous studies involving in vitro and in vivo models of PH have revealed that the treatment with baicalin and baicalein may be effective. This review summarizes the potential mechanisms driving the beneficial effects of baicalin and baicalein treatment on PH, including anti-inflammatory response, inhibition of pulmonary smooth muscle cell proliferation and endothelial-to-mesenchymal transformation, stabilization of the extracellular matrix, and mitigation of oxidative stress. The pharmacokinetics of these compounds have also been reviewed. The therapeutic potential of baicalin and baicalein warrants their continued study as natural treatments for PH.

Combined intermittent and sustained hypoxia is a novel and deleterious cardio-metabolic phenotype

STUDY OBJECTIVES

Chronic obstructive pulmonary disease and obstructive sleep apnea overlap syndrome is associated with excess mortality, and outcomes are related to the degree of hypoxemia. People at high altitudes are susceptible to periodic breathing, and hypoxia at altitude is associated with cardio-metabolic dysfunction. Hypoxemia in these scenarios may be described as superimposed sustained hypoxia (SH) plus intermittent hypoxia (IH), or overlap hypoxia (OH), the effects of which have not been investigated. We aimed to characterize the cardio-metabolic consequences of OH in mice.

METHODS

C57BL/6J mice were subjected to either SH (FiO2 = 0.10), IH (FiO2 = 0.21 for 12 h, and FiO2 oscillating between 0.21 and 0.06, 60 times/hour, for 12 h), OH (FiO2 = 0.13 for 12 h, and FiO2 oscillating between 0.13 and 0.06, 60 times/hour, for 12 h), or room air (RA), n = 8/group. Blood pressure and intraperitoneal glucose tolerance test were measured serially, and right ventricular systolic pressure (RVSP) was assessed.

RESULTS

Systolic blood pressure transiently increased in IH and OH relative to SH and RA. RVSP did not increase in IH, but increased in SH and OH by 52% (p < .001) and 20% (p = .001). Glucose disposal worsened in IH and improved in SH, with no change in OH. Serum low- and very-low-density lipoproteins increased in OH and SH, but not in IH. Hepatic oxidative stress increased in all hypoxic groups, with the highest increase in OH.

CONCLUSIONS

OH may represent a unique and deleterious cardio-metabolic stimulus, causing systemic and pulmonary hypertension, and without protective metabolic effects characteristic of SH.

Advances in Immunosuppressive Agents Based on Signal Pathway

Immune abnormality involves in various diseases, such as infection, allergic diseases, autoimmune diseases, as well as transplantation. Several signal pathways have been demonstrated to play a central role in the immune response, including JAK/STAT, NF-κB, PI3K/AKT-mTOR, MAPK, and Keap1/Nrf2/ARE pathway, in which multiple targets have been used to develop immunosuppressive agents. In recent years, varieties of immunosuppressive agents have been approved for clinical use, such as the JAK inhibitor tofacitinib and the mTOR inhibitor everolimus, which have shown good therapeutic effects. Additionally, many immunosuppressive agents are still in clinical trials or preclinical studies. In this review, we classified the immunosuppressive agents according to the immunopharmacological mechanisms, and summarized the phase of immunosuppressive agents.

Mechanisms of pulmonary vascular dysfunction in pulmonary hypertension and implications for novel therapies

Pulmonary hypertension (PH) is a serious disease characterized by various degrees of pulmonary vasoconstriction and progressive fibroproliferative remodeling and inflammation of the pulmonary arterioles that lead to increased pulmonary vascular resistance, right ventricular hypertrophy, and failure. Pulmonary vascular tone is regulated by a balance between vasoconstrictor and vasodilator mediators, and a shift in this balance to vasoconstriction is an important component of PH pathology, Therefore, the mainstay of current pharmacological therapies centers on pulmonary vasodilation methodologies that either enhance vasodilator mechanisms such as the NO-cGMP and prostacyclin-cAMP pathways and/or inhibit vasoconstrictor mechanisms such as the endothelin-1, cytosolic Ca2+, and Rho-kinase pathways. However, in addition to the increased vascular tone, many patients have a "fixed" component in their disease that involves altered biology of various cells in the pulmonary vascular wall, excessive pulmonary artery remodeling, and perivascular fibrosis and inflammation. Pulmonary arterial smooth muscle cell (PASMC) phenotypic switch from a contractile to a synthetic and proliferative phenotype is an important factor in pulmonary artery remodeling. Although current vasodilator therapies also have some antiproliferative effects on PASMCs, they are not universally successful in halting PH progression and increasing survival. Mild acidification and other novel approaches that aim to reverse the resident pulmonary vascular pathology and structural remodeling and restore a contractile PASMC phenotype could ameliorate vascular remodeling and enhance the responsiveness of PH to vasodilator therapies.

Mechanosensitive channel Piezo1 is required for pulmonary artery smooth muscle cell proliferation

Concentric pulmonary vascular wall thickening due partially to increased pulmonary artery (PA) smooth muscle cell (PASMC) proliferation contributes to elevating pulmonary vascular resistance (PVR) in patients with pulmonary hypertension (PH). Although pulmonary vasoconstriction may be an early contributor to increasing PVR, the transition of contractile PASMCs to proliferative PASMCs may play an important role in the development and progression of pulmonary vascular remodeling in PH. A rise in cytosolic Ca2+ concentration ([Ca2+]cyt) is a trigger for PASMC contraction and proliferation. Here, we report that upregulation of Piezo1, a mechanosensitive cation channel, is involved in the contractile-to-proliferative phenotypic transition of PASMCs and potential development of pulmonary vascular remodeling. By comparing freshly isolated PA (contractile PASMCs) and primary cultured PASMCs (from the same rat) in a growth medium (proliferative PASMCs), we found that Piezo1, Notch2/3, and CaSR protein levels were significantly higher in proliferative PASMCs than in contractile PASMCs. Upregulated Piezo1 was associated with an increase in expression of PCNA, a marker for cell proliferation, whereas downregulation (with siRNA) or inhibition (with GsMTx4) of Piezo1 attenuated PASMC proliferation. Furthermore, Piezo1 in the remodeled PA from rats with experimental PH was upregulated compared with PA from control rats. These data indicate that PASMC contractile-to-proliferative phenotypic transition is associated with the transition or adaptation of membrane channels and receptors. Upregulated Piezo1 may play a critical role in PASMC phenotypic transition and PASMC proliferation. Upregulation of Piezo1 in proliferative PASMCs may likely be required to provide sufficient Ca2+ to assure nuclear/cell division and PASMC proliferation, contributing to the development and progression of pulmonary vascular remodeling in PH.

TRPC6, a therapeutic target for pulmonary hypertension

Idiopathic pulmonary arterial hypertension (PAH) is a fatal and progressive disease. Sustained vasoconstriction due to pulmonary arterial smooth muscle cell (PASMC) contraction and concentric arterial remodeling due partially to PASMC proliferation are the major causes for increased pulmonary vascular resistance and increased pulmonary arterial pressure in patients with precapillary pulmonary hypertension (PH) including PAH and PH due to respiratory diseases or hypoxemia. We and others observed upregulation of TRPC6 channels in PASMCs from patients with PAH. A rise in cytosolic Ca2+ concentration ([Ca2+]cyt) in PASMC triggers PASMC contraction and vasoconstriction, while Ca2+-dependent activation of PI3K/AKT/mTOR pathway is a pivotal signaling cascade for cell proliferation and gene expression. Despite evidence supporting a pathological role of TRPC6, no selective and orally bioavailable TRPC6 antagonist has yet been developed and tested for treatment of PAH or PH. In this study, we sought to investigate whether block of receptor-operated Ca2+ channels using a nonselective blocker of cation channels, 2-aminoethyl diphenylborinate (2-APB, administered intraperitoneally) and a selective blocker of TRPC6, BI-749327 (administered orally) can reverse established PH in mice. The results from the study show that intrapulmonary application of 2-APB (40 µM) or BI-749327 (3-10 µM) significantly and reversibly inhibited acute alveolar hypoxia-induced pulmonary vasoconstriction. Intraperitoneal injection of 2-APB (1 mg/kg per day) significantly attenuated the development of PH and partially reversed established PH in mice. Oral gavage of BI-749327 (30 mg/kg, every day, for 2 wk) reversed established PH by ∼50% via regression of pulmonary vascular remodeling. Furthermore, 2-APB and BI-749327 both significantly inhibited PDGF- and serum-mediated phosphorylation of AKT and mTOR in PASMC. In summary, the receptor-operated and mechanosensitive TRPC6 channel is a good target for developing novel treatment for PAH/PH. BI-749327, a selective TRPC6 blocker, is potentially a novel and effective drug for treating PAH and PH due to respiratory diseases or hypoxemia.

Endothelial upregulation of mechanosensitive channel Piezo1 in pulmonary hypertension

Piezo is a mechanosensitive cation channel responsible for stretch-mediated Ca2+ and Na+ influx in multiple types of cells. Little is known about the functional role of Piezo1 in the lung vasculature and its potential pathogenic role in pulmonary arterial hypertension (PAH). Pulmonary arterial endothelial cells (PAECs) are constantly under mechanic stretch and shear stress that are sufficient to activate Piezo channels. Here, we report that Piezo1 is significantly upregulated in PAECs from patients with idiopathic PAH and animals with experimental pulmonary hypertension (PH) compared with normal controls. Membrane stretch by decreasing extracellular osmotic pressure or by cyclic stretch (18% CS) increases Ca2+-dependent phosphorylation (p) of AKT and ERK, and subsequently upregulates expression of Notch ligands, Jagged1/2 (Jag-1 and Jag-2), and Delta like-4 (DLL4) in PAECs. siRNA-mediated downregulation of Piezo1 significantly inhibited the stretch-mediated pAKT increase and Jag-1 upregulation, whereas downregulation of AKT by siRNA markedly attenuated the stretch-mediated Jag-1 upregulation in human PAECs. Furthermore, the mRNA and protein expression level of Piezo1 in the isolated pulmonary artery, which mainly contains pulmonary arterial smooth muscle cells (PASMCs), from animals with severe PH was also significantly higher than that from control animals. Intraperitoneal injection of a Piezo1 channel blocker, GsMTx4, ameliorated experimental PH in mice. Taken together, our study suggests that membrane stretch-mediated Ca2+ influx through Piezo1 is an important trigger for pAKT-mediated upregulation of Jag-1 in PAECs. Upregulation of the mechanosensitive channel Piezo1 and the resultant increase in the Notch ligands (Jag-1/2 and DLL4) in PAECs may play a critical pathogenic role in the development of pulmonary vascular remodeling in PAH and PH.

Heterozygous Tropomodulin 3 mice have improved lung vascularization after chronic hypoxia

The molecular mechanisms leading to high altitude pulmonary hypertension (HAPH) remains poorly understood. We previously analyzed the whole genome sequence of Kyrgyz highland population and identified eight genomic intervals having a potential role in HAPH. Tropomodulin 3 gene (TMOD3) which encodes a protein that binds and caps the pointed ends of actin filaments and inhibits cell migration, was one of the top candidates. Here we systematically sought additional evidence to validate the functional role of TMOD3. In-silico analysis reveals that some of the SNPs in HAPH associated genomic intervals were positioned in a regulatory region that could result in alternative splicing of TMOD3. In order to functionally validate the role of TMOD3 in HAPH, we exposed Tmod3-/+ mice to 4 weeks of constant hypoxia, i.e. 10% O2 and analyzed both functional (hemodynamic measurements) and structural (angiography) parameters related to HAPH. The hemodynamic measurements, such as right ventricular systolic pressure, a surrogate measure for pulmonary arterial systolic pressure, and right ventricular contractility (RV- ± dP/dt), increases with hypoxia did not separate between Tmod3-/+ and control mice. Remarkably, there was a significant increase in the number of lung vascular branches and total length of pulmonary vascular branches (p < 0.001) in Tmod3-/+ after 4 weeks of constant hypoxia as compared to controls. Notably, the Tmod3-/+ endothelial cells migration was also significantly higher than that from the wild-type littermates. Our results indicate that, under chronic hypoxia, lower levels of Tmod3 play an important role in the maintenance or neo-vascularization of pulmonary arteries.