Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare and life-threatening complication of pulmonary embolism. As existing animal models of CTEPH do not fully recapitulate complex disease pathophysiology, we report a new rat model for CTEPH evoked by repetitive embolization of the distal pulmonary artery branches with partially biodegradable alginate microspheres (MSs). MSs (180 ± 28 μm) were intravenously administered eight times at 4-day intervals; control animals received saline. The validity of the model was confirmed using transthoracic echocardiography, exercise testing, catheterization of the right ventricle, and histological examination of the lung and heart. The animals in the CTEPH group demonstrated a stable increase in right ventricular systolic pressure (RVSP) and decreased exercise tolerance. Histopathological examination revealed advanced medial hypertrophy in the small pulmonary arteries associated with fibrosis. The diameter of the main pulmonary artery was significantly larger in the CTEPH group than in the control group. Marinobufagenin and endothelin-1 serum levels were significantly elevated in rats with CTEPH. In conclusion, repetitive administration of alginate MSs in rats resulted in CTEPH development characterized by specific lung vasculature remodeling, reduced exercise tolerance, and a persistent rise in RVSP. The developed model can be used for pre-clinical testing of promising drug candidates.

Chronic thromboembolic pulmonary hypertension (CTEPH) develops in 1.5–2.0% of patients experiencing pulmonary embolism (PE) and is characterized by stable pulmonary artery obstruction, heart failure, and poor prognosis. Little is known about involvement of autonomic nervous system (ANS) in the mechanisms of CTEPH. This study was aimed at evaluation of the effect of vagal and sympathetic denervation, as well as stimulation of the parasympathetic nervous system, on the outcomes of CTEPH in rats. CTEPH was induced by multiple intravenous injections of alginate microspheres. Sympathetic and vagal denervation was performed using unilateral surgical ablation of the stellate ganglion and vagotomy, respectively. Stimulation of the parasympathetic nervous system was carried out by administering pyridostigmine. The effect of neuromodulatory effects was assessed in terms of hemodynamics, histology, and gene expression. The results demonstrated the key role of ANS in the development of CTEPH. Sympathetic denervation as well as parasympathetic stimulation resulted in attenuated pulmonary vascular remodeling. These salutary changes were associated with altered MMP2 and TIMP1 expression in the lung and decreased FGFb level in the blood. Unilateral vagotomy had no effect on physiological and morphological outcomes of the study. The data obtained contribute to the identification of new therapeutic targets for CTEPH treatment.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare complication of acute pulmonary embolism with poor clinical outcomes. Therapeutic approaches to prevention of fibrotic remodeling of the pulmonary vascular bed in CTEPH are limited. In this work, we tested the hypothesis that Janus kinase 1/2 (JAK1/2) inhibition with ruxolitinib might prevent and attenuate CTEPH in a rat model. CTEPH was induced by repeated embolization of the pulmonary artery with partially biodegradable 180 ± 30 μm alginate microspheres. Two weeks after the last injection of microspheres, ruxolitinib was administered orally at doses of 0.86, 2.58, and 4.28 mg/kg per day for 4 weeks. Prednisolone (1.475 mg/kg, i.m.) was used as a reference drug. Ruxolitinib in all doses as well as prednisolone reduced pulmonary vascular wall hypertrophy. Ruxolitinib at a dose of 2.58 mg/kg and prednisolone reduced vascular wall fibrosis. Prednisolone treatment resulted in decreased right ventricular systolic pressure. Pulmonary vascular resistance was lower in the prednisolone and ruxolitinib (4.28 mg/kg) groups in comparison with the placebo group. The plasma level of brain natriuretic peptide was lower in groups receiving ruxolitinib at doses of 2.58 and 4.28 mg/kg versus placebo. This study demonstrated that JAK1/2 inhibitor ruxolitinib dose-dependently reduced pulmonary vascular remodeling, thereby preventing CTEPH formation in rats.

HighlightsIL-8 and MCP-1 have a significant role in the CTEPH pathogenesis, which indicates the importance of nonspecific immunity in the formation and progression of CTEPH. The coupling between cytokines and hemodynamic parameters, cardiac structural changes and plasma biochemical parameters were determined. AbstractBackground. Chronic thromboembolic pulmonary hypertension (CTEPH) pathogenesis is complex and not fully understood. Particular attention to the microvascular damage genesis in CTEPH is given to aseptic inflammation, which in turn could be mediated through various molecular mechanisms. According to the conflicting and incomplete data on changes in the profile of factors controlling inflammation in CTEPH, research in this field would identify new therapeutic targets for the prevention and treatment of CTEPH.Aim. To study the profile of plasma proinflammatory cytokines in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and evaluate the coupling of these cytokines with the main morphofunctional and laboratory values of the disease severity.Methods. 34 patients with CTEPH were included in this study. To characterize the group, the following methods were used: echocardiographic examination, catheterization of the right cardiac chambers. Biomarkers of heart failure, systemic inflammation, as well as erythropoiesis and iron metabolism were assessed in all patients. The control group included 10 donors. To study the proinflammatory cytokine profile in plasma, interleukins (IL) 6, 8, 18, monocyte chemoattractant protein-1 (MCP-1) and matrix metalloproteinase 9 were determined using standard enzyme-linked immunosorbent assay (ELISA) kits.Results. Hemodynamic and morphofunctional changes in the pulmonary circulation specific to pulmonary hypertension were determined with catheterization of the right cardiac chambers and echocardiography. During plasma proinflammatory cytokines analysis, a significant increase in the level of IL-8 (p = 0.030) and MCP-1 (p = 0.031) in CTEPH group compared to the control group was observed. No significant differences for other analyzed markers were found. In the elaboration of the correlation analysis, moderate inverse coupling between proinflammatory markers and hemodynamic parameters characterizing the CTEPH severity were revealed, as well as positive correlations with parameters of remodeling of the right cardiac chambers and iron metabolism.Conclusion. The increased levels of IL-8 and MCP-1 in patients with CTEPH identified in the present study indicate a significant role of nonspecific immunity in the formation and progression of CTEPH. The coupling between cytokines and hemodynamic parameters, structural cardiac changes and plasma biochemical parameters were determined. Based on the obtained data, it is possible to develop new medicinal substances, targeting towards proinflammatory cytokines, their receptors and signaling pathways.

Ischemic stroke is one of the leading causes of disability and mortality. The key approaches to the treatment of this pathology are thrombolytic therapy and thromboaspiration. Despite their proven efficacy, the application of these methods is limited by a relatively narrow therapeutic window. There remains a great relevance in the further study of the molecular mechanisms of ischemic- reperfusion brain damage within the framework of the ischemic cascade concept. The impact on the mechanisms of induction and implementation of various types of programmed cell death with the help of pharmacological agents is a promising approach to reduce brain damage in ischemic stroke. This review considers the key processes leading to irreversible damage to neurons and their death. The mechanisms of formation and the role of excitotoxicity, calcium overload, oxidative and nitrosyl stress, mitochondrial dysfunction, as well as the triggering of signaling pathways of apoptosis and aseptic inflammation are considered in detail. The issue of various variants of cell death against the background of these pathological processes is discussed. Along with the consideration of signaling pathways that contribute to the progression of brain damage, special attention is paid to the activation of protective signaling mechanisms during ischemia, which provide an increase in cell resistance to death.

Aim. To develop a model of chronic thromboembolic pulmonary hypertension (CTEPH) in rats by embolization of the pulmonary vascular bed with microencapsulated fibrin (MF).Materials and methods. Microencapsulated fibrin (MF) was prepared by encapsulating fibrin particles smaller than 71 μm in sodium alginate. Non-encapsulated fibrin with a particle size of 71–200 µm was used as an alternative embolic particle. Modeling was performed on male Wistar rats. The animals were divided into 4 groups. Intact (INT) animals (n = 7) were administered normal saline intravenously. In the NF8 group (n = 14), non-encapsulated fibrin was injected as embolic particles 8 times every 4 days. In the MF5 group (n = 14), 0.5 ml MF (9,047 ± 430 particles) was administered intravenously 5 times every 5 days. In the MF8 group (n = 14), MF was administered 8 times every 4 days. Six weeks after the last injection of embolic particles, cardiac catheterization with manometry and histologic examination of the lungs were performed.Results. According to cardiac catheterization, right ventricular systolic pressure (RVSP) in the MF8 group was significantly higher compared to rats from the INT and NF8 groups (p < 0.05). The hypertrophy index and the percentage of collagen fibers in the structure of the vascular wall of the pulmonary artery branches were significantly higher in the MF5 and MF8 groups than in the INT and NF8 groups (p < 0.01). There were no significant differences between the MF5 and MF8 groups.Conclusion. A representative CTEPH model in rats was developed, characterized by a stable increase in RVSP and pronounced structural changes in the branches of the pulmonary artery.