Schistosomiasis-associated Pulmonary Arterial Hypertension Research Articles

Role and predictive value of microRNAs 204 and 210 in the diagnosis of pulmonary arterial hypertension and the distinction between idiopathic, systemic sclerosis, and schistosomiasis-associated pulmonary arterial hypertension

BackgroundPulmonary arterial hypertension is most of the time diagnosed late in the course of the disease and necessitates right cardiac catheterization which is an invasive and costly tool. MicroRNAs have a role in the pathogenesis of pulmonary hypertension, systemic sclerosis, and schistosomiasis and their dosages are easy and non-expensive. Therefore, determining their levels in the blood may be helpful in detecting PAH and differentiating its idiopathic form from those caused by systemic sclerosis and schistosomiasis.Purpose of the studyTo evaluate the role of microRNA (miR) 204 and miR-210 in the diagnosis of PAH and to distinguish between idiopathic PAH (IPAH), systemic sclerosis-associated PAH (SSc-PAH), and schistosomiasis-associated PAH (Sch-PAH) and to identify patients who may benefit from simple non-expensive and non-invasive methods in diagnosis of PAH.MethodsSixty patients with PAH and 30 subjects as control were enrolled in the study. PAH was diagnosed by right heart catheterization, echocardiography, and laboratory tests. Blood samples were taken from all patients for measuring miR-204 and miR-210.ResultsMiR-204 was downregulated in PAH and there was a highly significant difference between PAH and control (p = 0.003) with cut-off predictive value ≤ 0.15 µM and 70% sensitivity, 85% specificity with AUC (0.749). However, miR-204 failed to distinguish between IPAH, SSc-PAH, and Sch-PAH. MiR-210 was upregulated in PAH with a highly significant difference between PAH and control (p < 0.001) with cut-off predictive value ≥ 1.16 µM and 93.33% sensitivity, 85% specificity with AUC (0.917). MiiR-210 showed a significant difference between SSc-PAH and idiopathic PAH (P = 0.012) and between SSc-PAH and Sch-PAH (P = 0.035).ConclusionsMiR-204 and miR-210 are useful non-invasive and non-expensive markers for the diagnosis of PAH, miR-210 is an excellent predictor in the diagnosis of PAH and also miR-210 might be used to distinguish SSc-PAH from idiopathic PAH and Sch-PAH.

Abstract 15005: Tlr4/py14-Caveolin-1-Mediated Endothelial C-iap2 Expression During Schistosomiasis-Associated Pulmonary Arterial Hypertension

Introduction: During schistosomiasis-associated pulmonary arterial hypertension (Sch-PAH), hyperproliferation of abnormal endothelial cells (ECs) contributes to development of severe vascular lesions within the lungs; a life-threatening phenomenon that remains with no target therapy. Hypothesis: Here, we found that antigenic molecules from the major etiological agent of Sch-PAH, i.e., S. mansoni , amplify the secretion of the antiapoptotic protein c-IAP2 via TLR4-pY14Cav-1 signaling pathway, which we hypothesized to contribute to generation of an EC memory of survival and severity of PAH. Methods/Results: Cav-1 deficiency via shedding of extracellular vesicles (EVs) leads to survival of an apoptosis-resistant EC phenotype during idiopathic PAH. Similarly, S. mansoni egg antigens also reduced lung EC-Cav-1 expression, suggesting that Cav-1 also plays a role during pathogen-associated PAH. Cav-1 depletion via EVs precedes its phosphorylation at residue Tyr14 (pY14Cav-1), which in turn, contributes to EV loading. Among apoptotic regulators, IAPs have been found as a cargo of EVs in different conditions, including in TLR4-activated cells. Accordingly, our data indicates that S. mansoni egg antigen p40 also activated TLR4/NFkB-mediated signaling, inducing c-IAP2 expression and a time-dependent phosphorylation of Cav-1 in human lung microvascular EC (HMVEC-L: 228.2 +/- 38.28% of control; p&lt;0.05; n=4). Moreover, although Sm-p40 alone was unable to induce shedding of EVs, combination with NFkB-associated proinflammatory mediators (TNF-α, IL-6, and ATP), significantly increased EV shedding by HMVEC-L, suggesting that S. mansoni may epigenetically prime ECs, but co-factors are required to induce EV shedding. Finally, Sch-PAH model using EC- Cav1 -/- mice ( End-scl.Cre ERT2 ;Rosa mt/mg ;Cav1 fl/fl ) revealed that Cav-1 absence led to accumulation of eggs within the lungs and loss of eGFP+ cells, indicating that EC-Cav-1 phosphorylation may be required to development of Sch-PAH. Conclusions: Our data suggest that S. mansoni -induced pY14Cav-1 is associated to expression of the anti-apoptotic c-IAP2 protein, which may be critical for prolonged survival of a pathogenic EC phenotype during the development of Sch-PAH.

Schistosomiasis-Associated Pulmonary Arterial Hypertension

Schistosomiasis is a major cause of group 1 pulmonary arterial hypertension (PAH) worldwide. Schistosomiasis results from a parasitic infection present in over 200 million individuals worldwide. Schistosomiasis-associated PAH was initially thought to be obstructive due to egg embolization but has a pulmonary vascular pathology like other forms of group 1 PAH and can be treated using conventional PAH therapies. Mechanisms that underlie the development of schistosomiasis-associated PAH include type 2 inflammation which triggers TGF-β signaling; importantly, TGF-β signaling is a pathway shared with other PAH etiologies. However, many things which are unknown about this disease remain, including if the lung vascular pathology results from egg embolization causing localized inflammation and vessel remodeling, or if this is a form of portopulmonary hypertension resulting from schistosomiasis liver disease.

Guest Editors’ Memo

This issue of Advances in Pulmonary Hypertension highlights several associated conditions causing pulmonary arterial hypertension (PAH) that are of particular relevance globally and deserve to be on our radar: schistosomiasis, Human immunodeficiency virus (HIV), and liver disease. These well-known conditions provide unique challenges to our understanding and treatment of PAH.Schistosomiasis affects a shocking 200 million or more throughout the world, with 5–10% developing PAH. Yet it can be easy to forget that schistosomiasis is cause of Group I PAH. Brian Graham reviews the background, mechanisms, diagnosis, and treatment schistosomiasis-associated pulmonary arterial hypertension. Graham leaves us with several cutting-edge questions yet to be answered regarding this disease.Nicholas Kolaitis and Christopher Barnett provide us with an updated review on HIV-associated PAH. They take us through epidemiology, pathogenesis, and the impact of antiretroviral therapy. The approach to treatment includes a critical review of drug-drug interactions between HIV and PAH medications.Rosechelle Ruggiero and Sonja Bartolome deliver a focused review of portopulmonary hypertension for the treating provider. They take us through current definitions, clinical features, and management with a crucial focus on special considerations for liver transplantation.We gratefully thank all of our contributing authors for sharing their knowledge and insights. As the world shrinks, and our knowledge of mechanisms of disease and treatment grow, these articles are timely and well worth the read.

Progress of researches on schistosomiasis-associated pulmonary arterial hypertension

Schistosomiasis-associated pulmonary arterial hypertension (Sch-PAH) is categorized as WHO Group I PAH because its clinical manifestations, laboratory and hemodynamic features share with PAH of other etiologies, such as idiopathic, heritable, HIV and autoimmune disorders. Sch-PAH is usually a life-threatening complication of hepatosplenic schistosomiasis characterized by changes in the vascular wall, remodeling and vasoconstriction with lesions primarily located in the precapillary segments of the pulmonary vasculature, which may result in a marked and sustained increase in pulmonary vascular resistance, right ventricular failure and ultimately death. Although egg deposition into lung and subsequent inflammatory cascades are key factors in the pathogenesis of Sch-PAH, the exact pathogenesis, course of disease and treatment of Sch-PAH remain largely uncertain. This review mainly discusses the pathophysiological and immunological mechanisms of Sch-PAH, so as to provide insights into the clinical diagnosis and treatment of Sch-PAH.

Abstract 388: Role Of The Antiapoptotic C-iap2 On The Generation Of An Endothelial Memory In Schistosomiasis-associated Pulmonary Arterial Hypertension

Introduction: Schistosomiasis-associated Pulmonary Arterial Hypertension (Sch-PAH) is a life-threatening complication of chronic S. mansoni infection, which can evolve to heart failure and death. During PAH, hyperproliferation of apoptosis-resistant endothelial cells (ECs) has been extensively reported, but therapeutic approaches to reverse this pathological phenotype remain clinically challenging. Hypothesis: Thus, our hypothesis is that antigenic molecules from S. mansoni eggs amplify the secretion of inhibitor of apoptosis protein 2 (c-IAP2), leading to generation of an abnormal EC memory of survival and the development of PAH. Methods/Results: Previously, we showed that depletion of the anti-apoptotic protein Caveolin-1 (Cav-1) via shedding of extracellular vesicles (EVs) leads to the survival of an abnormal EC phenotype through an unclear mechanism. Analysis of survival-associated genes in isolated murine lung ECs from Flk1 +/GFP ;Cav1 -/- mice, revealed high expression of the anti-apoptotic genes BIRC3 and BIRC5 (which encodes cIAP2 and survivin, respectively) when compared to control ECs. Interesting, exposure to 1 μg/mL of the major S. mansoni egg antigen Sm-p40 induced time-dependent phosphorylation of Cav-1 at residue Tyr14 in human lung microvascular EC (HMVEC-L: 228.2 +/- 38.28% of control; p&lt;0.05; n=4), culminating in c-IAP2 expression with no difference on the constitutive expression of c-IAP1. Furthermore, Sm-p40 treatment of HMVEC-L in the presence of pro-inflammatory mediators IL-6, TNF-α, and ATP induced a significant release of EVs containing c-IAP2. Finally, in vivo analysis of lungs from S. mansoni -infected mice confirmed a significant decrease in Cav-1 expression unique to the egg-dependent granuloma area, indicating that local inflammatory response due to egg-derived antigenic molecules is essential for reprogramming and survival of an abnormal EC phenotype during Sch-PAH. Conclusions: Our data suggest that S. mansoni -induced Cav-1 depletion promotes the secretion of the anti-apoptotic c-IAP2 protein, which may be critical for prolonged survival of a pathogenic EC phenotype during the development of Sch-PAH.

Experimental Schistosoma japonicum-induced pulmonary hypertension.

Schistosomiasis, a major cause of pulmonary arterial hypertension (PAH) worldwide, is most clearly described complicating infection by one species, Schistosoma mansoni. Controlled exposure of mice can be used to induce Type 2 inflammation-dependent S. mansoni pulmonary hypertension (PH). We sought to determine if another common species, S. japonicum, can also cause experimental PH. Schistosome eggs were obtained from infected mice, and administered by intraperitoneal sensitization followed by intravenous challenge to experimental mice, which underwent right heart catheterization and tissue analysis. S. japonicum sensitized and challenged mice developed PH, which was milder than that following S. mansoni sensitization and challenge. The degree of pulmonary vascular remodeling and Type 2 inflammation in the lungs was similarly proportionate. Cross-sensitization revealed that antigens from either species are sufficient to sensitize for intravenous challenge with either egg, and the degree of PH severity depended on primarily the species used for intravenous challenge. Compared to a relatively uniform distribution of S. mansoni eggs, S. japonicum eggs were observed in clusters in the lungs. S. japonicum can induce experimental PH, which is milder than that resulting from comparable S. mansoni exposure. This difference may result from the distribution of eggs in the lungs, and is independent of which species is used for sensitization. This result is consistent with the clearer association between S. mansoni infection and the development of schistosomiasis-associated PAH in humans.

Rationale and design of a screening study to detect schistosomiasis-associated pulmonary hypertension in Ethiopia and Zambia.

Schistosomiasis is a major cause of pulmonary arterial hypertension (PAH) worldwide, but the prevalence and risk factors for schistosomiasis‐associated PAH (SchPAH) development are not well understood. Schistosomiasis‐associated hepatosplenic disease (SchHSD) is thought to be a major risk factor for PAH development. Herein, we describe our plans for prospectively screening SchHSD subjects for clinical evidence of PAH at two major academic medical centers and national referral hospitals in Addis Ababa, Ethiopia and Lusaka, Zambia. The screening study will primarily be conducted by echocardiography, in addition to clinical assessments. Plasma samples will be drawn and banked for subsequent analysis based on preclinical animal model rationale. If successful, this study will demonstrate feasibility of conducting prospective cohort studies of SchPAH screening in schistosomiasis‐endemic regions of Africa, and provide initial data on clinic‐based disease prevalence and potential mechanistic biomarkers underlying disease pathogenesis.

Abstract P138: Schistosoma Mansoni- Induced Shedding Of Extracellular Vesicles From Lung Microvascular Endothelial Cells

Introduction: Schistosomiasis-associated Pulmonary Arterial Hypertension (Sch-PAH) is a life-threatening complication of chronic Schistosoma mansoni infection. Sch-PAH is marked by obliteration and remodeling of the pulmonary vasculature in response to S. mansoni eggs. Remodeled and occluded vessels increase vascular resistance and can lead to heart failure and death. Currently, there are no target therapies for the treatment of Sch-PAH. Hypothesis: S. mansoni egg-derived antigens alter pulmonary endothelial cell (EC) Caveolin-1 (Cav-1) expression and phosphorylation contributing to the loading and shedding of extracellular vesicles (EVs), which in turn stimulates abnormal EC survival leading to Sch-PAH. Methods/Results: Immunohistology and western blot analysis of lungs from S. mansoni -infected mice revealed a significant decrease in Cav-1 expression in the egg-dependent granuloma area when compared to uninfected control animals, indicating that local S. mansoni -associated molecules and inflammatory mediators contribute to Cav-1 depletion. Previously we showed that upon vascular injury, Cav-1 deficiency leads to the survival of an abnormal EC phenotype through an unclear mechanism. Analysis of survival-associated genes in isolated lung ECs from Flk1 +/GFP ; Cav1 -/- mice, revealed a high expression of the anti-apoptotic BIRC2 and BIRC5 (known as c-IAP2 and surviving, respectively) when compared to control ECs. Interesting, in vitro exposure to the major S. mansoni egg antigen, Sm-p40 (1 μg/mL), induced time-dependent phosphorylation of Cav-1 Tyr14 in human lung microvascular ECs (HMVEC-L; 228.2 +/- 38.28% of control; p&lt;0.05; n=4), which culminated in c-IAP2 expression. Furthermore, Sm-p40 treatment of HMVEC-L increased ERK1/2 phosphorylation, which in presence of pro-inflammatory mediators IL-6, TNF-a, and ATP, significantly increased the shedding of EVs implicating P-ERK1/2 in the mechanism of shedding of Cav-1-EVs. Conclusions: This work is uncovering the biological role and potential translational relevance of pathogen-induced EC-Cav-1 depletion via shedding of EVs during Sch-PAH.

Schistosomiasis-associated pulmonary arterial hypertension: a systematic review

Schistosomiasis-associated pulmonary arterial hypertension (Sch-PAH) is a life-threatening complication of chronic hepatosplenic schistosomiasis. It is suggested to be the leading cause of pulmonary arterial hypertension (PAH) worldwide. However, pathophysiological data on Sch-PAH are scarce. We examined the hypothesis that there are pronounced similarities in pathophysiology, haemodynamics, and survival of Sch-PAH and idiopathic PAH (iPAH).This systematic review and meta-analysis was registered in the PROSPERO database (identifier CRD42018104066). A systematic search and review of the literature was performed according to PRISMA guidelines for studies published between 01 January 1990 and 29 June 2018.For Sch-PAH, 18 studies evaluating pathophysiological mechanisms, eight studies on haemodynamics (n=277), and three studies on survival (n=191) were identified. 16 clinical registries reporting data on haemodynamics and survival including a total of 5792 patients with iPAH were included for comparison. Proinflammatory molecular pathways are involved in both Sch-PAH and iPAH. The transforming growth factor (TGF)-β signalling pathway is upregulated in Sch-PAH and iPAH. While there was no difference in mean pulmonary artery pressure (54±17 mmHg versus 55±15 mmHg, p=0.29), cardiac output (4.4±1.3 L·min-1 versus 4.1±1.4 L·min-1, p=0.046), and cardiac index (2.6±0.7 L·min-1·m-2 versus 2.3±0.8 L·min-1·m-2, p<0.001) were significantly higher in Sch-PAH compared to iPAH, resulting in a lower pulmonary vascular resistance in Sch-PAH (10±6 Woods units versus 13±7 Woods units, p<0.001). 1- and 3-year survival were significantly better in the Sch-PAH group (p<0.001).Sch-PAH and iPAH share common pathophysiological mechanisms related to inflammation and the TGF-β signalling pathway. Patients with Sch-PAH show a significantly better haemodynamic profile and survival than patients with iPAH.

Schistosomiasis-associated pulmonary arterial hypertension: survival in endemic area in Brazil

BackgroundThe survival of schistosomiasis-associated pulmonary arterial hypertension (Sch-PAH) patients in endemic areas is unknown, but can be estimated using predictive equations. MethodsWe retrospectively analyzed all consecutive patients diagnosed with Sch-PAH referred to the Pronto SocorroCardiologico de Pernambuco between 2004 and 2010 using specific therapy and measured laboratory, diagnostic imaging, and baseline hemodynamic parameters. Observed and predicted survivals according to the National Institutes of Health (NIH) and Pulmonary Hypertension Connection (PHC) registry equations were compared by the Kaplan–Meier method, log-rank test and Cox proportional hazards model. ResultsSixty-eight patients (47 [69.1%] women) observed for a mean of 3.1years (range, 7–72months), median survival was 74months, and 42 (61.7%) survived. The sex and age distributions were similar for functional class I/II and III/IV patients. Hemodynamic abnormalities were severe: mean right atrial pressure, 12.6±6.2mmHg; mean pulmonary artery pressure, 60.3±13.69mmHg; pulmonary vascular resistance, 14.62±7.04 Wood units; and cardiac index, 2.3±0.8L/min/m2. The usual idiopathic PAH predictors were not prognostic in Sch-PAH patients. The 1-, 3- and 5-year survival rates were 92.1%, 75.2%, and 50.8%, respectively, and those estimatedby the NIH and PHC registry equations were 68%, 45% and 32% (p=0.001), and 93%, 79% and 68% (p=0.340), respectively. ConclusionsSch-PAH patients in endemic areas have severe hemodynamic profiles and reduced long-term survivaldespite treatment. The PHC registry equation may be a useful tool to estimate survival in Sch-PAH.

IL-13 enhances mesenchymal transition of pulmonary artery endothelial cells via down-regulation of miR-424/503 in vitro

Pulmonary arterial hypertension (PAH) has a major effect on life expectancy with functional degeneracy of the lungs and right heart. Interleukin-13 (IL-13), one of the type 2 cytokines mainly associated with allergic diseases, has recently been reported to be associated with Schistosomiasis-associated PAH which shares pathological features with other forms of PAH, such as idiopathic PAH and connective tissue disease-associated PAH. But a direct pathological role of IL-13 in the development of PAH has not been explored. We examined the effects of recombinant human IL-13 on the function of primary human pulmonary artery endothelial cells (HPAECs) to examine how IL-13 influences exacerbation of PAH. IL-13 increased the expression of Rictor, which is a key molecule of mammalian target of rapamycin complex 2. Treatment of IL-13 induced HPAEC migration via Rictor. Rictor was directly regulated by both miR-424 and 503 (miR-424/503). Therefore, IL-13 increases Rictor level by regulating miR-424/503, causing the increase of HPAEC migration. Since enhancement of HPAEC migration in the lung is thought to be associated with PAH, these data suggest that IL-13 takes some roles in exacerbating PAH.

Schistosomiasis and pulmonary hypertension

Schistosomiasis is one of the most prevelant parazitic diseases in the world. It is endemic in more than 70 countries, and more than 200 million people worldwide are infected with Schistosoma. Pulmonary hypertension (PHT) is one of the chronic complications of schistosomiasis. The exact pathogenesis of schistosomiasis-associated pulmonary hypertension (S-PHT) remains unclear, although several mechanisms such as parazitic arterial embolisation, pulmonary arteriopathy, and portopulmonary hypertension have been suggested. Pathological pulmonary vascular changes in S-PHT were found similar to those in idiopathic pulmonary arterial hypertension (IPAH). The fact that schistosomiasis is one of the most common causes of pulmonary arterial hypertension (PAH), particularly in the developing countries, underlines the importance of enhancing our knowledge on this disease. Developments in the treatment of PAH have resulted in improved prognosis and significant increase in life expectancy and quality of life in the last two decades, which has enhanced the importance of S-PHT. Schistosomiasis is treated with praziquantel. Nevertheless, there is limited evidence that this treatment is effective for PHT. Although antihelmintic medications do not lead to significant improvement, they have beneficial effects and may slow down disease progression. Using PAH-specific treatments in the patients with schistosomiasis-associated PAH (S-PAH) can improve prognosis. However, inadequate clinical studies and limited sources in the endemic regions restrict extensive usage of these expensive medications. Further studies are required to determine the efficacy of these treatment modalities.

TGF-\u03b2 activation by bone marrow-derived thrombospondin-1 causes Schistosoma- and hypoxia-induced pulmonary hypertension

Pulmonary arterial hypertension (PAH) is an obstructive disease of the precapillary pulmonary arteries. Schistosomiasis-associated PAH shares altered vascular TGF-β signalling with idiopathic, heritable and autoimmune-associated etiologies; moreover, TGF-β blockade can prevent experimental pulmonary hypertension (PH) in pre-clinical models. TGF-β is regulated at the level of activation, but how TGF-β is activated in this disease is unknown. Here we show TGF-β activation by thrombospondin-1 (TSP-1) is both required and sufficient for the development of PH in Schistosoma-exposed mice. Following Schistosoma exposure, TSP-1 levels in the lung increase, via recruitment of circulating monocytes, while TSP-1 inhibition or knockout bone marrow prevents TGF-β activation and protects against PH development. TSP-1 blockade also prevents the PH in a second model, chronic hypoxia. Lastly, the plasma concentration of TSP-1 is significantly increased in subjects with scleroderma following PAH development. Targeting TSP-1-dependent activation of TGF-β could thus be a therapeutic approach in TGF-β-dependent vascular diseases.

Pulmonary arterial hypertension in schistosomiasis.

Schistosomiasis is one of the most prevalent parasitic diseases in the world, being present in more than 70 countries. Pulmonary hypertension is one of the several chronic complications of schistosomiasis; particularly in developing countries, schistosomiasis-associated pulmonary arterial hypertension might represent one of the most prevalent causes of pulmonary arterial hypertension. New epidemiological data reinforce the importance of schistosomiasis in the context of pulmonary hypertension; furthermore, the inflammatory components of the pathophysiology of pulmonary hypertension associated with schistosomiasis have been recently explored, opening the perspective of new targets to be explored. Clinical and hemodynamic features of this particular complication of schistosomiasis, and the role of targeted therapies in this setting, have been better described in recent years. The importance of schistosomiasis-associated pulmonary hypertension is now recognized with better knowledge about its pathophysiology and management. Nevertheless, there is a need for better understanding the predisposal factors (genetic, environmental and so on) for the development of pulmonary hypertension in schistosomiasis as a way to prevent it from occurring. Furthermore, better control programs to decrease disease transmission are still missing, ensuring that we will have to face this devastating complication of schistosomiasis for a long future.

The Causal Role of IL-4 and IL-13 in Schistosoma mansoni Pulmonary Hypertension.

The etiology of schistosomiasis-associated pulmonary arterial hypertension (PAH), a major cause of PAH worldwide, is poorly understood. Schistosoma mansoni exposure results in prototypical type-2 inflammation. Furthermore, transforming growth factor (TGF)-β signaling is required for experimental pulmonary hypertension (PH) caused by Schistosoma exposure. We hypothesized type-2 inflammation driven by IL-4 and IL-13 is necessary for Schistosoma-induced TGF-β-dependent vascular remodeling. Wild-type, IL-4(-/-), IL-13(-/-), and IL-4(-/-)IL-13(-/-) mice (C57BL6/J background) were intraperitoneally sensitized and intravenously challenged with S. mansoni eggs to induce experimental PH. Right ventricular catheterization was then performed, followed by quantitative analysis of the lung tissue. Lung tissue from patients with schistosomiasis-associated and connective tissue disease-associated PAH was also systematically analyzed. Mice with experimental Schistosoma-induced PH had evidence of increased IL-4 and IL-13 signaling. IL-4(-/-)IL-13(-/-) mice, but not single knockout IL-4(-/-) or IL-13(-/-) mice, were protected from Schistosoma-induced PH, with decreased right ventricular pressures, pulmonary vascular remodeling, and right ventricular hypertrophy. IL-4(-/-)IL-13(-/-) mice had less pulmonary vascular phospho-signal transducer and activator of transcription 6 (STAT6) and phospho-Smad2/3 activity, potentially caused by decreased TGF-β activation by macrophages. In vivo treatment with a STAT6 inhibitor and IL-4(-/-)IL-13(-/-) bone marrow transplantation also protected against Schistosoma-PH. Lung tissue from patients with schistosomiasis-associated and connective tissue disease-associated PAH had evidence of type-2 inflammation. Combined IL-4 and IL-13 deficiency is required for protection against TGF-β-induced pulmonary vascular disease after Schistosoma exposure, and targeted inhibition of this pathway is a potential novel therapeutic approach for patients with schistosomiasis-associated PAH.

Pulmonary artery enlargement in schistosomiasis associated pulmonary arterial hypertension

BackgroundSchistosomiasis associated pulmonary arterial hypertension (Sch-PAH) might represent the most prevalent form of PAH worldwide. In Sch-PAH, the presence of aneurismal dilation of the pulmonary artery has been described, although it is still a matter of debate whether on average the pulmonary artery is more enlarged in Sc-PAH than IPAH.MethodsWe retrospectively evaluated patients with IPAH (n = 25) and Sch-PAH (n = 22) who underwent computed tomography pulmonary angiogram and right heart catheterization.ResultsSch-PAH patients were older and presented less severe hemodynamic profiles. Main pulmonary artery diameter (MPAD) was greater in Sch-PAH than IPAH (4.5 ± 1.8 vs 3.7 ± 1.1 cm, p = 0.018). For the same level of mean pulmonary artery pressure, the MPAD in Sch-PAH was 0.89 cm larger than in IPAH (Covariance model p = 0.02).ConclusionThis study demonstrated that pulmonary artery enlargement is more pronounced in Sch-PAH than IPAH, independently of mean pulmonary artery pressure level, suggesting that this is more likely a feature of Sch-PAH.

Pulmonary Arterial Hypertension in the Southern Hemisphere

Pulmonary arterial hypertension (PAH) is a rare and ultimately fatal disorder of the pulmonary vasculature. There is increasing interest in the worldwide characteristics of patients with PAH, although data coming from the Southern Hemisphere remain scarce. The objective of this study was to describe a cohort of incident patients with PAH from a large reference center in Brazil. All consecutive patients who received a diagnosis of PAH by right-sided heart catheterization between 2008 and 2013 were included in the study. A total of 178 patients with newly diagnosed PAH were enrolled in the study (mean age, 46 years; female/male ratio, 3.3:1; 45.5% in New York Heart Association functional class III or IV). Idiopathic PAH (IPAH), connective tissue disease (CTD), and schistosomiasis-associated PAH (Sch-PAH) accounted for 28.7%, 25.8%, and 19.7% of all cases, respectively. The patients were treated with phosphodiesterase type 5 inhibitors (66%), endothelin receptor antagonists (27%), or a combination of both (5%). For the PAH group as a whole, the estimated survival rate 3 years after diagnosis was 73.9%. The prognosis for the patients with CTD was worse than that for the patients with IPAH and Sch-PAH (P = .03). The distribution of PAH causes and the baseline characteristics in our registry clearly differ from the previously published European and US-based registries. These differences highlight the importance of regional registries and also raise questions regarding the need to better account for such differences in future clinical trials.

Schistosomiasis and the pulmonary vasculature (2013 Grover Conference series).

Inflammation is associated with multiple forms of pulmonary arterial hypertension (PAH), including autoimmune (scleroderma) and infectious (HIV, schistosomiasis) etiologies. More than 200 million people worldwide are infected with Schistosoma, predominantly in Brazil, Africa, the Middle East, and South Asia. Schistosomiasis causes PAH in about 6.1% of those chronically infected and is particularly associated with the species Schistosoma mansoni. Treatment for schistosomiasis-associated PAH includes antihelminthic treatment, if active infection is present (although associated with little immediate benefit to the pulmonary hypertension), and then pharmacologic treatment with targeted pulmonary vascular therapies, including phosphodiesterase type 5 inhibitors and endothelin receptor antagonists. The pathophysiological mechanism by which this parasitic infection causes pulmonary hypertension is unknown but is unlikely to be simple mechanical obstruction of the pulmonary vasculature by parasite eggs. Preexisting hepatosplenic disease due to Schistosoma infection is likely important because of portopulmonary hypertension and/or because it allows egg embolization to the lung by portocaval shunts. Potential immune signaling originating in the periegg granulomas causing the pulmonary vascular disease includes the cytokines interleukin (IL)-4, IL-6, IL-13, and transforming growth factor β. Modulating these pathways may be possible targets for future therapy of schistosomiasis-associated PAH specifically, and study of this disease may provide novel insights into other inflammatory causes of PAH.

Role of IL‐4 and IL‐13 in Schistosoma‐induced pulmonary hypertension (LB780)

Background: Schistosomiasis‐associated pulmonary arterial hypertension (PAH) occurs in the context of Th2 inflammation, which is induced by IL‐4 and IL‐13. We had previously observed that TGF‐β signaling is necessary for Schistosoma‐induced pulmonary hypertension (PH) in the mouse. We hypothesized that IL‐4 and IL‐13 were necessary for the TGF‐β‐induced pulmonary vascular disease induced by Schistosoma.Methods: Wild type, IL‐13YFP, IL‐4GFP, IL‐4‐/‐, IL‐13‐/‐ and IL‐4‐/‐IL‐13‐/‐ mice (N=5‐17 per group) were intraperitoneally (IP) sensitized with 175 S. mansoni eggs/gram body weight, two weeks later intravenously (IV) challenged via tail vein with the same dose of eggs, and one week thereafter underwent right ventricular catheterization followed by quantitative histologic and protein analysis, or lung digestion and flow cytometry. Lung tissue from patients who died of schistosomiasis‐associated PAH was studied by immunostaining.Results: The lungs of patients with schistosomiasis‐associated PAH and mice with experimental disease had an increase in IL‐13, IL‐4Rα, phospho‐STAT6 and periostin, a target of IL‐13 signaling. Flow cytometry with IL‐13YFP and IL‐4GFP mice identified both of these cytokines were produced by CD4+ T‐cells. IL‐4‐/‐IL‐13‐/‐ mice, but not IL‐4‐/‐IL13+/+ or IL4+/+IL‐13‐/‐ mice, were protected from Schistosoma‐induced vascular remodeling, although the elevated right ventricular pressure persisted. Immunostaining of Schistosoma‐exposed mice demonstrated decreased phospho‐STAT6, perivascular TGF‐β ligand, and intravascular nuclear phospho‐Smad2/3 in IL4/IL13 double‐deficient mice only.Conclusions: Combined IL‐4 and IL‐13 deficiency are required for protection against Schistosoma‐induced pulmonary vascular remodeling.