Rho-Kinase Inhibition Ameliorates Dasatinib-Induced Endothelial Dysfunction and Pulmonary Hypertension

Endothelium as a Source of Cardiovascular Toxicity From Antitumor Kinase Inhibitors

Kinase inhibitors (KIs) targeting oncogenic molecular pathways have revolutionized cancer therapy. By directly targeting specific tumor-driving kinases, targeted therapies have fewer side effects compared with chemotherapy. Despite the enhanced specificity, cardiovascular side effects have emerged with many targeted cancer therapies that limit long-term outcomes in patients with cancer. Endothelial cells lining all blood vessels are critical to cardiovascular health and are also exposed to circulating levels of systemic anticancer therapies. Both on- and off-target perturbation of signaling pathways from KIs can cause endothelial dysfunction, resulting in cardiovascular toxicity. As such, the endothelium is a potential source, and also a therapeutic target for prevention, of cardiovascular toxicity. In this review, we examine the evidence for KI-induced endothelial cell dysfunction as a mechanism for the cardiovascular toxicities of vascular endothelial growth factor inhibitors, BCR-Abl (breakpoint cluster region-Abelson proto-oncogene) KIs, Bruton tyrosine inhibitors, and emerging information regarding endothelial toxicity of newer classes of KIs.

An association between Dasatinib, elevated left atrial pressure and pleural effusion

BACKGROUND

Tyrosine kinase inhibitors (TKI), such as Dasatinib, are effective in the treatment of chronic myeloid leukemia (CML) but associated with development of pleural effusions (PE). The relationship between haemodynamic parameters identified on transthoracic echocardiogram (TTE) such as elevated estimated left atrial pressure (LAP), and PE development is unknown. This study aims to describe associations between Dasatinib, elevated LAP and PE.

METHODS

This was a retrospective study of 71 CML patients who underwent TTE during treatment with various TKIs. Descriptive analysis was performed to identify associations between TKI use, PE and elevated LAP on TTE. Multivariate logistic regression was performed to identify predictors of elevated LAP.

RESULTS

There were 36 patients treated with Dasatinib, 15 Nilotinib, and 20 Imatinib. Those treated with Dasatinib had higher rates of elevated LAP (44% vs 7% Nilotinib vs 10% Imatinib, p < 0.01) and PE (39% vs 7% vs 0%, p < 0.01). In the 15 patients who developed PE, 14 (93%) patients were treated with Dasatinib. Patients with PE had higher rates of elevated LAP (67% vs 16%, p < 0.01). Nineteen (26.8%) patients in the entire cohort had elevated LAP. After multivariate adjustment, Dasatinib (OR 33.50, 95% CI = 4.99-224.73, p < 0.01) and age (OR 1.12, 95% CI = 1.04-1.20, p < 0.01) were associated with elevated LAP.

CONCLUSIONS

Among patients with CML, there was an association between Dasatinib use, PE and elevated LAP on TTE. These findings are hypothesis generating and further studies are required to evaluate the utility of elevated LAP on TTE as a novel marker for prediction and surveillance of PE.

A Comprehensive Review of Cancer Drug-Induced Cardiotoxicity in Blood Cancer Patients: Current Perspectives and Therapeutic Strategies

OPINION STATEMENT

Cardiotoxicity has emerged as a serious outcome catalyzed by various therapeutic targets in the field of cancer treatment, which includes chemotherapy, radiation, and targeted therapies. The growing significance of cancer drug-induced cardiotoxicity (CDIC) and radiation-induced cardiotoxicity (CRIC) necessitates immediate attention. This article intricately unveils how cancer treatments cause cardiotoxicity, which is exacerbated by patient-specific risks. In particular, drugs like anthracyclines, alkylating agents, and tyrosine kinase inhibitors pose a risk, along with factors such as hypertension and diabetes. Mechanistic insights into oxidative stress and topoisomerase-II-B inhibition are crucial, while cardiac biomarkers show early damage. Timely intervention and prompt treatment, especially with specific agents like dexrazoxane and beta-blockers, are pivotal in the proactive management of CDIC.

Recent Advancement in Elimination Strategies and Potential Rejuvenation Targets of Senescence

Cellular senescence is a state of exiting the cell cycle, resisting apoptosis, and changing phenotype. Senescent cells (SCs) can be identified by large, distorted morphology and irreversible inability to replicate. In early development, senescence has beneficial roles like tissue patterning and wound healing, where SCs are cleared by the immune system. However, there is a steep rise in SC number as organisms age. The issue with SC accumulation stems from the loss of cellular function, alterations of the microenvironment, and secretions of pro-inflammatory molecules, consisting of cytokines, chemokines, matrix metalloproteinases (MMPs), interleukins, and extracellular matrix (ECM)-associated molecules. This secreted cocktail is referred to as the senescence-associated secretory phenotype (SASP), a hallmark of cellular senescence. The SASP promotes inflammation and displays a bystander effect where paracrine signaling turns proliferating cells into senescent states. To alleviate age-associated diseases, researchers have developed novel methods and techniques to selectively eliminate SCs in aged individuals. Although studies demonstrated that selectively killing SCs improves age-related disorders, there are drawbacks to SC removal. Considering favorable aspects of senescence in the body, this paper reviews recent advancements in elimination strategies and potential rejuvenation targets of senescence to bring researchers in the field up to date.

Pentastatin, a matrikine of the collagen IVα5, is a novel endogenous mediator of pulmonary endothelial dysfunction

Deposition of basement membrane components, such as collagen IVα5, is associated with altered endothelial cell function in pulmonary hypertension. Collagen IVα5 harbors a functionally active fragment within its C-terminal noncollageneous (NC1) domain, called pentastatin, whose role in pulmonary endothelial cell behavior remains unknown. Here, we demonstrate that pentastatin serves as a mediator of pulmonary endothelial cell dysfunction, contributing to pulmonary hypertension. In vitro, treatment with pentastatin induced transcription of immediate early genes and proinflammatory cytokines and led to a functional loss of endothelial barrier integrity in pulmonary arterial endothelial cells. Mechanistically, pentastatin leads to β1-integrin subunit clustering and Rho/ROCK activation. Blockage of the β1-integrin subunit or the Rho/ROCK pathway partially attenuated the pentastatin-induced endothelial barrier disruption. Although pentastatin reduced the viability of endothelial cells, smooth muscle cell proliferation was induced. These effects on the pulmonary vascular cells were recapitulated ex vivo in the isolated-perfused lung model, where treatment with pentastatin-induced swelling of the endothelium accompanied by occasional endothelial cell apoptosis. This was reflected by increased vascular permeability and elevated pulmonary arterial pressure induced by pentastatin. This study identifies pentastatin as a mediator of endothelial cell dysfunction, which thus might contribute to the pathogenesis of pulmonary vascular disorders such as pulmonary hypertension.NEW & NOTEWORTHY This study is the first to show that pentastatin, the matrikine of the basement membrane (BM) collagen IVα5 polypeptide, triggers rapid pulmonary arterial endothelial cell barrier disruption, activation, and apoptosis in vitro and ex vivo. Mechanistically, pentastatin partially acts through binding to the β1-integrin subunit and the Rho/ROCK pathway. These findings are the first to link pentastatin to pulmonary endothelial dysfunction and, thus, suggest a major role for BM-matrikines in pulmonary vascular diseases such as pulmonary hypertension.

Hypoxia activates GPR146 which participates in pulmonary vascular remodeling by promoting pyroptosis of pulmonary artery endothelial cells

BACKGROUND

Hypoxia is a risk factor of pulmonary hypertension (PH) and may induce pulmonary artery endothelial cells (PAECs) injury and inflammation. Pyroptosis is a form of cell death through maturation and secretion of inflammatory mediators. However, the mechanistic association of pyroptosis, PAECs injury, and inflammation remain unknown. Here, we explored in detail the effects of hypoxia on pyroptosis of PAECs.

EXPERIMENTAL APPROACH

Using RNA sequencing, we screened differentially expressed genes in pulmonary artery tissue of a Sugen5416/hypoxia-induced (SuHx) rat PH model. We examined the role of the differentially expressed gene G-protein coupled receptor 146 (GPR146) in PAECs through immunohistochemistry, immunofluorescence, CCK-8 assays, western blotings, real-time PCR, detection of reactive oxygen species, and lactate dehydrogenase release experiments.

KEY RESULTS

According to RNA sequencing, GPR146 was 11.64-fold increased in the SuHx-induced PH model, compared to the controls. Further, GPR146 was highly expressed in pulmonary arterial hypertension human lung tissue and SuHx-induced rat PH lung tissues. Our results suggested that the expression of pyroptosis-related proteins was markedly increased under hypoxia, both in vivo and in vitro, which was inhibited by silencing GPR146. Moreover, inhibiting NLRP3 or caspase-1 effectively suppressed cleavage of caspase-1, production of interleukin (IL)-1β, IL-6, and IL-18 in PAECs by hypoxia and overexpression of GPR146.

CONCLUSION

Our results indicated that GPR146 induced pyroptosis and inflammatory responses through the NLRP3/caspase-1 signaling axis, thus triggering endothelial injury and vascular remodeling. Hypoxia may promote PAECs pyroptosis through upregulation of GPR146 and thereby facilitate the progression of PH. Taken together, these insights may help identify a novel target for the treatment of PH.

Adverse reactions after treatment with dasatinib in chronic myeloid leukemia: Characteristics, potential mechanisms, and clinical management strategies

Dasatinib, a second-generation tyrosine kinase inhibitor, is recommended as first-line treatment for patients newly diagnosed with chronic myeloid leukemia (CML) and second-line treatment for those who are resistant or intolerant to therapy with imatinib. Dasatinib is superior to imatinib in terms of clinical response; however, the potential pulmonary toxicities associated with dasatinib, such as pulmonary arterial hypertension and pleural effusion, may limit its clinical use. Appropriate management of dasatinib-related severe events is important for improving the quality of life and prognosis of patients with CML. This review summarizes current knowledge regarding the characteristics, potential mechanisms, and clinical management of adverse reactions occurring after treatment of CML with dasatinib.

Imatinib attenuates reperfusion injury in a rat model of acute myocardial infarction

Following an acute myocardial infarction, reperfusion of an occluded coronary artery is often accompanied by microvascular injury, leading to worse long-term prognosis. Experimental studies have revealed the potential of tyrosine-kinase inhibitor imatinib to reduce vascular leakage in various organs. Here, we examined the potential of imatinib to attenuate microvascular injury in a rat model of myocardial reperfusion injury. Isolated male Wistar rat hearts (n = 20) in a Langendorff system and male Wistar rats (n = 37) in an in vivo model were randomly assigned to imatinib or placebo and subjected to ischaemia and reperfusion. Evans-blue/Thioflavin-S/TTC staining and Cardiac Magnetic Resonance Imaging were performed to assess the extent of reperfusion injury. Subsequently, in vivo hearts were perfused ex vivo with a vascular leakage tracer and fluorescence and electron microscopy were performed. In isolated rat hearts, imatinib reduced global infarct size, improved end-diastolic pressure, and improved rate pressure product recovery compared to placebo. In vivo, imatinib reduced no-reflow and infarct size with no difference between imatinib and placebo for global cardiac function. In addition, imatinib showed lower vascular resistance, higher coronary flow, and less microvascular leakage in the affected myocardium. At the ultrastructural level, imatinib showed higher preserved microvascular integrity compared to placebo. We provide evidence that low-dose imatinib can reduce microvascular injury and accompanying myocardial infarct size in a rat model of acute myocardial infarction. These data warrant future work to examine the potential of imatinib to reduce reperfusion injury in patients with acute myocardial infarction.

Endothelial dysfunction as a complication of anti-cancer therapy

Recent strides in anti-cancer therapeutics have improved longevity and led to a growing population of cancer survivors, who are increasingly likely to die of other causes. Treatment-induced cardiotoxicity is a complication of several therapeutic agents with acute and long-term consequences for cancer patients. Vascular endothelial dysfunction is a precursor and hallmark of ischemic coronary disease and may play a role in anti-cancer therapy-induced cardiotoxicity. This review summarizes clinical evidence for endothelial dysfunction following anti-cancer therapy and extends the discussion to include the impact of therapeutic agents on conduit arteries and the microcirculation. We highlight the role of innate immune system activation and cross-talk between inflammation and oxidative stress as pathogenic mechanisms underlying anti-cancer therapy-induced vascular toxicity. Understanding the impact of anti-cancer agents on the vascular endothelium will inform therapeutic approaches to prevent or reverse treatment-induced cardiotoxicity and may serve as an important tool to predict, monitor, and prevent adverse cardiovascular outcomes in patients undergoing treatment.

Melatonin Attenuates Dasatinib-Aggravated Hypoxic Pulmonary Hypertension via Inhibiting Pulmonary Vascular Remodeling

Dasatinib treatment is approved as first-line therapy for chronic myeloid leukemia. However, pulmonary hypertension (PH) is a highly morbid and often fatal side-effect of dasatinib, characterized by progressive pulmonary vascular remodeling. Melatonin exerts strong antioxidant capacity against the progression of cardiovascular system diseases. The present work aimed to investigate the effect of melatonin on dasatinib-aggravated hypoxic PH and explore its possible mechanisms. Dasatinib-aggravated rat experimental model of hypoxic PH was established by utilizing dasatinib under hypoxia. The results indicated that melatonin could attenuate dasatinib-aggravated pulmonary pressure and vascular remodeling in rats under hypoxia. Additionally, melatonin attenuated the activity of XO, the content of MDA, the expression of NOX4, and elevated the activity of CAT, GPx, and SOD, the expression of SOD2, which were caused by dasatinib under hypoxia. In vitro, dasatinib led to decreased LDH activity and production of NO in human pulmonary microvascular endothelial cells (HPMECs), moreover increased generation of ROS, and expression of NOX4 both in HPMECs and primary rat pulmonary arterial smooth muscle cells (PASMCs) under hypoxia. Dasatinib up-regulated the expression of cleaved caspase-3 and the ratio of apoptotic cells in HPMECs, and also elevated the percentage of S phase and the expression of Cyclin D1 in primary PASMCs under hypoxia. Melatonin ameliorated dasatinib-aggravated oxidative damage and apoptosis in HPMECs, meanwhile reduced oxidative stress level, proliferation, and repressed the stability of HIF1-α protein in PASMCs under hypoxia. In conclusion, melatonin significantly attenuates dasatinib-aggravated hypoxic PH by inhibiting pulmonary vascular remodeling in rats. The possible mechanisms involved protecting endothelial cells and inhibiting abnormal proliferation of smooth muscle cells. Our findings may suggest that melatonin has potential clinical value as a therapeutic approach to alleviate dasatinib-aggravated hypoxic PH.

Oxidative Stress: Meeting Multiple Targets in Pathogenesis of Vascular Endothelial Dysfunction

Vascular endothelium is the innermost lining of blood vessels, which maintains vasoconstriction and vasodilation. Loss of vascular tone is a hallmark for cardiovascular disorders. Though there are numerous factors, such as over activation of renin angiotensin aldosterone system, kinases, growth factors, etc. play crucial role in induction and progression of vascular abrasion. Interestingly, dysregulation of these pathways either enhances the intensity of oxidative stress, or these pathways are affected by oxidative stress. Thus, oxidative stress has been considered a key culprit in the progression of vascular endothelial dysfunction. Oxidative stress induced by reactive oxygen and nitrogen species causes abnormal gene expression, alteration in signal transduction, and the activation of pathways leading to induction and progression of vascular injury. In addition, numerous antioxidants have been noted to possess promising therapeutic potential in preventing the development of vascular endothelial dysfunction. Therefore, we have focused on current perspectives in oxidative stress signalling to evaluate common biological processes whereby oxidative stress plays a crucial role in the progression of vascular endothelial dysfunction.

Differential Expression Profile of microRNAs and Tight Junction in the Lung Tissues of Rat With Mitomycin-C-Induced Pulmonary Veno-Occlusive Disease

Background

Pulmonary veno-occlusive disease (PVOD) is characterized by increased pulmonary vascular resistance. Currently, there is a lack of effective treatment. It is of great significance to explore molecular targets for treatment. This study investigated the differential expression profile of miRNAs and tight junction in the lung tissues of rats with mitomycin-C (MMC)-induced PVOD.

Methods

A total of 14 rats were divided into the control group and he PVOD group. We measured mean pulmonary arterial pressure (mPAP) and right ventricular hypertrophy index (RVHI). Pathological changes including those in lung tissues, pulmonary venules, and capillary were detected by H&E and orcein staining. Western blot was used to detect GCN2, ZO-1, occludin, and claudin-5 expression. We analyzed the miRNAs profile in the rat lung tissues by high-throughput sequencing. The top differentially expressed miRNAs were validated by using real-time polymerase chain reaction (RT-PCR).

Results

There were severe pulmonary artery hypertrophy/hyperplasia, thickening, and occlusion in the small pulmonary veins, pulmonary edema, and dilated capillaries in MMC-induced rats with PVOD. In addition, mPAP and RVHI were significantly increased (P < 0.05). The expression of GCN2 was significantly decreased (P < 0.05). A total of 106 differentially expressed miRNAs were identified. According to the fold changes, the top ten upregulated miRNAs were miRNA-543-3p, miRNA-802-5p, miRNA-493-3p, miRNA-539-3p, miRNA-495, miRNA-380-5p, miRNA-214-5p, miRNA-539-5p, miRNA-190a-3p, and miRNA-431. The top 10 downregulated miRNAs were miRNA-201-3p, miRNA-141-3p, miRNA-1912-3p, miRNA-500-5p, miRNA-3585-5p, miRNA-448-3p, miRNA-509-5p, miRNA-3585-3p, miRNA-449c-5p, and miRNA-509-3p. RT-PCR confirmed that miRNA-214-5p was upregulated, while miRNA-141-3p was downregulated (P < 0.05). Functional analysis showed various signaling pathways and metabolic processes, such as fatty acid biosynthesis, tight junction, and the mTOR signaling pathway. In addition, the expression of the tight junction-related protein of ZO-1, occludin, and claudin-5 was significantly decreased in rats with PVOD (P < 0.05).

Conclusion

miRNAs may be involved in the pathogenesis of PVOD. Furthermore, ZO-1, occludin, and claudin-5 verification confirmed that the tight junction may be involved in the development of the disease.

A narrative review on adverse effects of dasatinib with a focus on pharmacotherapy of dasatinib-induced pulmonary toxicities

Chronic myeloid leukemia (CML), a myeloproliferative disorder caused by the over activity of BCR-ABL1 (breakpoint cluster region-Abelson), has been successfully treated by Tyrosine kinase inhibitors (TKIs). While imatinib is known as the first-line treatment of CML, in some cases other TKIs including dasatinib, nilotinib, bosutinib, and ponatinib may be preferred. Dasatinib, a second-generation TKI, inhibits multiple family kinases including BCR-ABL, SRC family kinases, receptor kinases, and TEC family kinases. It is effective against most imatinib-resistant cases except T315I mutation. Despite the superiority of dasatinib in its hematologic and cytogenetic responses in CML compared to imatinib, its potentially harmful pulmonary complications including pleural effusion (PE) and pulmonary arterial hypertension (PAH) may limit its use. Appropriate management of these serious adverse reactions is critical in both improving the quality of life and the outcome of the patient. In this narrative review, we will scrutinize the pulmonary complications of dasatinib and focus on the management of these toxicities.

Exploiting polypharmacology to dissect host kinases and kinase inhibitors that modulate endothelial barrier integrity

Kinase inhibitors are promising drugs to stabilize the endothelial barrier following inflammatory damage. However, our limited knowledge of how kinase signaling activates barrier-restorative pathways and the complexity of multi-target drugs have hindered drug discovery and repurposing efforts. Here, we apply a kinase regression approach that exploits drug polypharmacology to investigate endothelial barrier regulation. A screen of 28 kinase inhibitors identified multiple inhibitors that promote endothelial barrier integrity and revealed divergent barrier phenotypes for BCR-ABL drugs. Target deconvolution predicted 50 barrier-regulating kinases from diverse kinase families. Using gene knockdowns, we identified kinases with a role in endothelial barrier regulation and dissected different mechanisms of action of barrier-protective kinase inhibitors. These results demonstrate the importance of polypharmacology in the endothelial barrier phenotype of kinase inhibitors and provide promising new leads for barrier-strengthening therapies.

[Analysis of endothelial dysfunction in the context of pleural effusions of various origins using skin thermometry]

OBJECTIVE

To analyze the mechanisms and severity of endothelial dysfunction in patients with pleural effusion of various origins using skin thermometry.

MATERIAL AND METHODS

We studied microcirculation in 135 patients with pleural effusions of various origins. Local skin thermometry and computer wavelet analysis were performed in 3-5 days after thoracoscopy with pleural biopsy using Microtest-100WF device with a temperature measuring resolution of 0.001°C. We estimated endothelial, myogenic and neurogenic indices using spectral analysis of skin temperature fluctuations in a range 0.0095-2 Hz. The control group comprised 40 healthy participants aged 23-36 years.

RESULTS

Three groups of patients were distinguished depending on the cause of effusion: malignant pleural effusions (n=65, 48.1%); inflammatory pleural effusions (para-pneumonic, post-traumatic, pancreatogenic, tuberculous) (n=58, 43%); transudates (hepatogenic, cardiogenic, and nephrogenic) (n=12, 8.9%). There were no significant differences in vascular tone in response to local heating of the second finger of the hand up to 40°C. Measurements were carried out within 10 min in all groups. Patients with diabetes mellitus and cardiovascular diseases (n=48, 35.6%) had significant decrease of thermal vasodilation index in endothelial range up to 2.93±1.77, in the control group - up to 4.21±2.40 (p=0.041).

CONCLUSION

Endothelial dysfunction is a universal non-specific aspect in pathogenesis of various diseases. This process is essential in pleural effusion. Local thermometry and computer wavelet analysis revealed no significant differences between patients with malignant, inflammatory and transudative pleural effusions. Pleural effusions in the context of cardiovascular pathology and/or diabetes mellitus occur due to impaired vasodilatation mechanisms in endothelial range.

Inhibition of Rho-kinase is involved in the therapeutic effects of atorvastatin in heart ischemia/reperfusion

The aim of the present study was to investigate the effects of atorvastatin against heart ischemia/reperfusion (I/R) injury and its potential underlying mechanism. Rats were allocated into the following groups: Sham, I/R, atorvastatin (10 mg/kg daily), fasudil (10 mg/kg daily) and atorvastatin + fasudil in combination. Drugs were administered for 2 weeks prior to I/R injury. I/R was established by ligating the left anterior descending branch (LAD) for 30 min and releasing the ligature for 180 min. The I/R group was found to have increased myocardial infarct size, cardiomyocyte apoptosis, levels of plasma interleukin (IL)-6 and tumor necrosis factor (TNF)-α, superoxide dismutase (SOD) activity, malondialdehyde (MDA) levels and Rho-kinase activity compared with the other treatment groups (P<0.05). Moreover, pretreatment with atorvastatin significantly attenuated Rho-kinase activity, myocardial infarct size, cardiomyocyte apoptosis, levels of plasma IL-6 and TNF-α, SOD activity and MDA levels, and upregulated nitric oxide production. It was also indicated that the specific Rho-kinase inhibitor, fasudil, had the same effects as atorvastatin in I/R. Therefore, the present results suggested atorvastatin may lead to cardiovascular protection, which may be mediated by Rho-kinase inhibition in heart I/R injury.

Pulmonary complications of Bcr-Abl tyrosine kinase inhibitors

Tyrosine kinase inhibitors (TKIs) targeting the Bcr-Abl oncoprotein revolutionised the treatment of chronic myelogenous leukaemia. Following the success of imatinib, second- and third-generation molecules were developed. Different profiles of kinase inhibition and off-target effects vary between TKIs, which leads to a broad spectrum of potential toxicities.

Pulmonary complications are most frequently observed with dasatinib but all other Bcr-Abl TKIs have been implicated. Pleural effusions are the most frequent pulmonary complication of TKIs, usually associated with dasatinib and bosutinib. Pulmonary arterial hypertension is an uncommon but serious complication of dasatinib, which is often reversible upon discontinuation. Bosutinib and ponatinib have also been associated with pulmonary arterial hypertension, while imatinib has not. Rarely, interstitial lung disease has been associated with TKIs, predominantly with imatinib.

Mechanistically, dasatinib affects maintenance of normal pulmonary endothelial integrity by generating mitochondrial oxidative stress, inducing endothelial apoptosis and impairing vascular permeability in a dose-dependent manner. The mechanisms underlying other TKI-related complications are largely unknown. Awareness and early diagnosis of the pulmonary complications of Bcr-Abl TKIs is essential given their seriousness, potential reversibility, and impact on future treatment options for the underlying chronic myelogenous leukaemia.

Application of Cell Impedance as a Screening Tool to Discover Modulators of Intraocular Pressure

Purpose: To identify new targets and compounds involved in mediating cellular contractility or relaxation in trabecular meshwork (TM) cells and test their efficacy in an ex vivo model measuring outflow facility. Methods: A low-molecular weight compound library composed of 3,957 compounds was screened for cytoskeletal changes using the Acea xCelligence impedance platform in immortalized human NTM5 TM cells. Hits were confirmed by 8-point concentration response and were subsequently evaluated for impedance changes in 2 primary human TM strains, as well as cross-reactivity in bovine primary cells. A recently described bovine whole eye perfusion system was used to evaluate effects of compounds on aqueous outflow facility. Results: The primary screen conducted was robust, with Z' values >0.5. Fifty-two compounds were identified in the primary screen and confirmed to have concentration-dependent effects on impedance in NTM5 cells. Of these, 9 compounds representing distinct drug classes were confirmed to modulate impedance in both human primary TM cells and bovine cells. One of these compounds, wortmannin, an inhibitor of phosphoinositide 3-kinase, increased outflow facility by 11%. Conclusions: A robust phenotypic assay was developed that enabled identification of contractility modulators in immortalized TM cells. The screening hits were translatable to primary TM cells and modulated outflow facility in an ex vivo perfusion assay.

Tyrosine Kinase Inhibitors in Leukemia and Cardiovascular Events: From Mechanism to Patient Care

Targeted oncology therapies have revolutionized cancer treatment over the last decade and have resulted in improved prognosis for many patients. This advance has emanated from elucidation of pathways responsible for tumorigenesis followed by targeting of these pathways by specific molecules. Cardiovascular care has become an increasingly critical aspect of patient care in part because patients live longer, but also due to potential associated toxicities from these therapies. Because of the targeted nature of cancer therapies, cardiac and vascular side effects may additionally provide insights into the basic biology of vascular disease. We herein provide the example of tyrosine kinase inhibitors utilized in chronic myelogenous leukemia to illustrate this medical transformation. We describe the vascular considerations for the clinical care of chronic myelogenous leukemia patients as well as the emerging literature on mechanisms of toxicities of the individual tyrosine kinase inhibitors. We additionally postulate that basic insights into toxicities of novel cancer therapies may serve as a new platform for investigation in vascular biology and a new translational research opportunity in vascular medicine.

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.

Increasing the effectiveness of tyrosine kinase inhibitor (TKI) in combination with a statin in reducing liver fibrosis

It has been shown that both nilotinib as a tyrosine kinase inhibitor, and atorvastatin as a rho-kinase inhibitor, have antifibrotic effects. Therefore, considering the relationship between these two pathways, this study aimed to investigate the effects of their co-treatment against hepatic stellate cells (HSCs) activation and liver fibrosis. For this purpose, the activation of HSCs coincided with these therapies. Also, liver fibrosis by carbon tetrachloride (CCl₄ ) was induced in male Wistar rats and treated simultaneously with these compounds. The expression of alpha-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF), Ras homolog gene family, and member A (RhoA)/Rho-associated protein kinase (ROCK) in HSCs were measured. The expression of transforming growth factor beta-1 (TGF-β1), its receptor (TβRII), CTGF, and platelets derived growth factor (PDGF), in the livers, were also investigated, all by real-time PCR and western blot analysis. Also, histopathologic and immunohistochemical evaluations were performed to evaluate changes in liver fibrosis during treatment. The results indicated the down-regulation of RhoA/ROCK, CTGF, and α-SMA, and inhibition of the HSCs activation toward myofibroblasts. The results also showed that the combined use of atorvastatin and nilotinib has significantly higher inhibitory effects. The antifibrotic effects of atorvastatin and nilotinib co-administration were also observed by histopathologic and immunohistochemical observations, and inhibiting the expression of TGF-β1, TβRII, CTGF, and PDGF. Taken together, this study revealed that co-administration of nilotinib-atorvastatin has novel antifibrotic effects, by inhibiting RhoA/ROCK, and CTGF pathway. Therefore, the importance of the common pathway of RhoA/ROCK and CTGF, in reducing fibrosis may almost be concluded.

EXPRESS: Pulmonary hypertension with dasatinib and other tyrosine kinase inhibitors

Dasatinib and other tyrosine kinase inhibitors are commonly utilized in the management of chronic myelogenous leukemia. Pulmonary hypertension is an important adverse event associated with dasatinib. Mechanisms for pulmonary hypertension include pulmonary endothelial injury, apoptosis, and increased susceptibility to other triggers for pulmonary hypertension. The diagnosis is suspected based on symptoms, suggested by echocardiographic findings, and confirmed with right heart catheterization. Management includes discontinuation of dasatinib and initiation of pulmonary vasodilators. Persistent pulmonary hypertension is present in up to one third of patients after cessation of dasatinib. Other tyrosine kinase inhibitors, including bosutinib, lapatinib, and ponatinib have also been implicated in pulmonary hypertension in small series, although evidence for causation is less robust. A high index of suspicion, continued vigilance for pulmonary hypertension with long-term use, and early therapy are important in optimizing outcomes in this population.