Pulmonary hypertension related to drugs and toxins

Immune Cells in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a complex and serious cardiopulmonary disease; it is characterised by increased pulmonary arterial pressure and pulmonary vascular remodelling accompanied by disordered endothelial and smooth muscle cell proliferation within pulmonary arterioles and arteries. Although recent reports have suggested that dysregulated immunity and inflammation are key players in PAH pathogenesis, their roles in PAH progression remain unclear. Intriguingly, altered host immune cell distribution, number, and polarisation within the lung arterial vasculature have been linked to disease development. This review mainly focusses on the roles of different immune cells in PAH and discusses the underlying mechanisms.

Thyrotoxicosis presenting as exertional dyspnea and pulmonary hypertension: Case report and review of literature

Objectives:

In this case study, we describe a 35-year-old woman with pulmonary hypertension that was secondary to thyrotoxicosis who presented with exertional dyspnea. In the approach to exertional dyspnea, detailed physical examination and laboratory findings helped to get the diagnosis.

Methods:

Echocardiography showed right ventricular systolic pressure = 60 mmHg. A suppressed thyroid-stimulating hormone was seen in lab tests. The patient was treated with radioactive iodine.

Results:

Palpitations and shortness of breath improved, and both her thyroid-stimulating hormone and T4 levels decreased. Echocardiography and the pulmonary pressure were normal after treatment.

Conclusions:

Thyrotoxicosis is one of the etiologies of pulmonary hypertension, but the exact etiology and pathogenesis remain unknown. Some patients may have symptomatic pulmonary hypertension that can be resolved by hyperthyroidism treatment.

Investigation of mutual pharmacokinetic interactions between macitentan, a novel endothelin receptor antagonist, and sildenafil in healthy subjects

AIM

To study the mutual pharmacokinetic interactions between macitentan, an endothelin receptor antagonist, and sildenafil in healthy male subjects.

METHODS

In this open-label, randomized, three way crossover study, 12 healthy male subjects received the following oral treatments: A) a loading dose of 30 mg macitentan on day 1 followed by 10 mg once daily for 3 days, B) sildenafil 20 mg three times a day for 3 days and a single 20 mg dose on day 4 and C) both treatments A and B concomitantly. Plasma concentration-time profiles of macitentan and its active metabolite ACT-132577 (treatments A and C) and sildenafil and its N-desmethyl metabolite (treatments B and C) were determined on day 4 and analyzed non-compartmentally.

RESULTS

The pharmacokinetics of macitentan were not affected by sildenafil. In the presence of sildenafil Cmax and AUCτ of the metabolite ACT-132577 decreased with geometric mean ratios (90% confidence interval (CI)) of 0.82 (0.76, 0.89) and 0.85 (90% CI 0.80, 0.91), respectively. In the presence of macitentan, plasma concentrations of sildenafil were higher than during treatment with sildenafil alone, resulting in increased Cmax and AUCτ values. The respective geometric mean ratios were 1.26 (90% CI 1.07, 1.48) and 1.15 (90% CI 0.94, 1.41). The pharmacokinetics of N-desmethylsildenafil were not affected by macitentan. All treatments were well tolerated.

CONCLUSION

A minor, not clinically relevant, pharmacokinetic interaction was observed between macitentan and sildenafil. Based on these results, no dose adjustment of either compound appears necessary during concomitant treatment with macitentan and sildenafil.

MicroRNA in pulmonary vascular disease

MicroRNA (miRNA) are short noncoding RNA that regulate gene expression by inhibiting translation or promoting degradation of target mRNA. miRNA are key regulators of a wide range of cellular processes and their discovery has revolutionized our understanding of gene regulatory networks. Pulmonary arterial hypertension (PAH) is a debilitating and fatal disease characterized by remodeling of pulmonary arteries and right heart failure. Factors including sustained pulmonary vasoconstriction, inflammation, and altered cellular signaling pathways drive disease through pulmonary artery endothelial dysfunction, smooth muscle cell proliferation, and the recruitment of circulating cells. miRNA have been shown to regulate many of the key drivers of pathology, yet the role of only a limited number of miRNA has been recognized in PAH. Investigation of the diverse regulatory functions of miRNA offers the potential to further understanding of the cellular pathology of PAH and to provide much needed diagnostic and therapeutic strategies. This review focuses on recent advances in the investigation of miRNA in PAH.

Molecular pathogenesis of pulmonary arterial hypertension

Recent clinical and experimental studies are redefining the cellular and molecular bases of pulmonary arterial hypertension (PAH). The genetic abnormalities first identified in association with the idiopathic form of PAH--together with a vast increase in our understanding of cell signaling, cell transformation, and cell-cell interactions; gene expression; microRNA processing; and mitochondrial and ion channel function--have helped explain the abnormal response of vascular cells to injury. Experimental and clinical studies now converge on the intersection and interactions between a genetic predisposition involving the BMPR2 signaling pathway and an impaired metabolic and chronic inflammatory state in the vessel wall. These deranged processes culminate in an exuberant proliferative response that occludes the pulmonary arterial (PA) lumen and obliterates the most distal intraacinar vessels. Here, we describe emerging therapies based on preclinical studies that address these converging pathways.

New approaches to the treatment of pulmonary hypertension: from bench to bedside

Pulmonary hypertension (PH) is a severe, life-threatening disease for which there are no effective curative therapies. A diverse group of agents such as prostacyclins, endothelin antagonists, phosphodiesterase inhibitors, calcium channel blockers, diuretics, inotropic agents, and anticoagulants are used to treat PH; however, none of these agents have a marked effect upon survival. Among the new agents that promise treatment of PH are rho-kinase inhibitors and soluble guanylate cyclase stimulators. Although these new classes of agents have beneficial effects in experimental animal models and clinical studies, they are not selective in their actions on the pulmonary vascular bed. This manuscript reviews the actions of rho-kinase inhibitors and soluble guanylate cyclase stimulators on the pulmonary vascular bed. It is our hypothesis that these new agents may be more effective than current therapies in the treatment of PH. Moreover, new methods in the delivery of these agents to the lung need to be developed so that their main effects will be exerted in the pulmonary vascular bed and their systemic effects can be minimized or avoided.

Hyperthyroidism and pulmonary hypertension

In recent years, many authors have described several cases revealing an association between hyperthyroidism and pulmonary hypertension (PH). This observational study was designed to evaluate the incidence of PH in hyperthyroidism and was set in a department of internal medicine and pulmonary diseases with an out-patients department of endocrinology. Thirty-four patients, 25 women and nine men, with a mean age of 38 +/- 15 SD years participated. Twenty had Graves' disease and 14 had a nodular goitre. The patients were divided into two equally matched groups: those with a recently diagnosed hyperthyroidism, taking no drugs (group 1; n = 17) and those in a euthyroid state taking methimazole (group 2; n= 17). Transthoracic Doppler echocardiography was performed and systolic pulmonary artery pressurements of (PAPs) was determined by the tricuspid regurgitation method using the Bernoulli equation. Measurements of triiodothyronine, tetraiodothyronine, free thyroxine (Ft4), thyroid-stimulating hormone (TSH) and antithyroglobulin and antimicrosomal antibodies were also taken. We found a mild PH in seven patients of group 1 and in none of group 2. The mean +/- SD systolic pulmonaryartery pressurewas 28.88 +/- 6.41 in group 1 and 22.53 +/- 1.84 ingroup 2 (P<0.0001). A correlation was found between the TSH value and PAPs (r = -082;P < 0.001) and Ft4 and PAPs (r = 0 85; P < 0.001) in group 1. These findings indicate the presence of a frequent association between PH and hyperthyroidism. We suggest that hyperthyroidism be included in the differential diagnosis of PH.

Risk factors for pulmonary arterial hypertension

The present limitations in knowledge of the potential risk factors for PPH undoubtedly are attributable to the facts that PPH is a rare disease with an unknown pathogenesis and lacking large case series. Moreover, definite epidemiologic data are rare and ideally should be obtained from epidemiologic surveys such as large case-control studies. The increased incidence of the disease in young women, the familial cases, the association with autoimmune disorders, and the recent discovery that mutation of the PPH1 gene may not be restricted to familial PPH support the hypothesis that the development of pulmonary hypertension likely implies an individual susceptibility or predisposition, which is probably genetically determined. It is also now commonly believed that the development of pulmonary hypertension in some of these predisposed individuals could be hastened or precipitated by various expression factors (some of them yet unrecognized), such as ingestion of certain drugs or diets, portal hypertension, or HIV infection.