Systemic sclerosis-associated pulmonary arterial hypertension

Future perspectives in pulmonary arterial hypertension

While there have been advances in the field of pulmonary arterial hypertension (PAH), disease management remains suboptimal for many patients. The development of novel treatments and strategies can provide opportunities to target other mechanisms that play a role in the complex pathobiology of PAH outside of the three main pathophysiological pathways. In this review, we highlight some of the potential PAH therapies or techniques that are being, or have been, investigated in phase II clinical trials. This review also discusses potential points for consideration in the development of novel therapies that target putative disease mediators or modifiers.

Novel therapies and well-designed trials are important for improving the management of PAH patientshttp://ow.ly/YHPY304XdvH

Beneficial effects of long-term treatment with bosentan on the development of pulmonary arterial hypertension in patients with systemic sclerosis

Objective

To investigate the effects of long-term treatment with bosentan on pulmonary arterial hypertension (PAH) in patients with systemic sclerosis.

Methods

Patients with systemic sclerosis were followed between 2003 and 2014; those who developed digital ulcers were treated with standard regimens of bosentan. Patients were assessed at baseline and every 12 months using transthoracic Doppler echocardiography, 6-min walking distance test, Borg dyspnoea index and monitoring of plasma levels of 76-amino-acid N-terminal probrain natriuretic peptide. Patients who developed PAH underwent right heart catheterization to confirm the diagnosis.

Results

Sixty-nine patients with systemic sclerosis were enrolled in the study. Of these, 25 developed digital ulcers and received treatment with bosentan; the remaining 44 comprised the control group. None of the patients treated with bosentan developed PAH during the follow-up period. Furthermore, in these patients the mean ± SD systolic pulmonary arterial pressure significantly decreased from 33.64 ± 2.91 mmHg at baseline to 26.20 ± 1.78 mmHg at the end of the follow-up period. In contrast, in the control group, seven patients developed PAH during the follow-up period, with the mean ± SD systolic pulmonary arterial pressure significantly increasing from 33.57 ± 2.75 mmHg at baseline to 39.41 ± 4.11 mmHg at the end of the follow-up period.

Conclusion

Long-term treatment with bosentan reduces the risk of developing PAH in patients with systemic sclerosis.

Association Between Initial Oral Therapy and Outcomes in Systemic Sclerosis-Related Pulmonary Arterial Hypertension

OBJECTIVE

To compare time to clinical worsening (TTCW) based on initial oral therapy for pulmonary arterial hypertension (PAH) in patients with systemic sclerosis (SSc)-related PAH.

METHODS

Using data from the Pulmonary Hypertension Assessment and Recognition of Outcomes in Scleroderma (PHAROS) registry (a multicenter prospective observational study enrolling SSc patients with incident pulmonary hypertension), we selected patients with group 1 PAH (World Health Organization Clinical Classification system) who received initial therapy (for 6 months) with an endothelin receptor antagonist (ERA), a phosphodiesterase 5 (PDE5) inhibitor, or a combination of these 2 agents (ERA/PDE5 inhibitor). The main outcome was TTCW, defined as the first occurrence of death, PAH-related hospitalization, lung transplantation, initiation of parenteral prostacyclin treatment, or worsening symptoms.

RESULTS

Ninety-eight patients (24 in the ERA group, 59 in the PDE5 inhibitor group, and 15 in the ERA/PDE5 inhibitor group) were included. No significant differences in the baseline characteristics of the patients were observed. TTCW was significantly worse in patients in the ERA group compared with those in the PDE5 inhibitor group or the ERA/PDE5 inhibitor group. Ten patients (41.6%) in the ERA group died during the 3-year observation period, compared with 4 patients (6.8%) in the PDE5 inhibitor group and 1 patient (6.7%) in the ERA/PDE5 inhibitor group. Baseline factors that were independently associated with a shorter TTCW were initial treatment with an ERA (hazard ratio [HR] 2.63 [P = 0.009]), lower diffusing capacity for carbon monoxide (HR 0.69 per 10% of predicted change [P = 0.04]), and higher pulmonary vascular resistance (HR 1.10 per Wood unit change [P = 0.007]).

CONCLUSION

Compared with initial treatment with a PDE5 inhibitor or combination therapy with an ERA and a PDE5 inhibitor, initial therapy with an ERA in patients with SSc-related PAH was associated with significantly worse TTCW, even after adjustment for commonly accepted prognostic factors. Further study into the optimal initial oral therapy for patients with SSc-related PAH is needed.

The Effects of Antigen-Specific IgG1 Antibody for the Pulmonary-Hypertension-Phenotype and B Cells for Inflammation in Mice Exposed to Antigen and Fine Particles from Air Pollution

Air pollution is known to exacerbate chronic inflammatory conditions of the lungs including pulmonary hypertension, cardiovascular diseases and autoimmune diseases. Directly pathogenic antibodies bind pro-inflammatory cell receptors and cause or exacerbate inflammation. In contrast, anti-inflammatory antibody isotypes (e.g. mouse immunoglobulin G1, IgG1) bind inhibitory cell receptors and can inhibit inflammation. Our previous studies showed that co-exposure to antigen and urban ambient particulate matter (PM_2.5) induced severe pulmonary arterial thickening and increased right ventricular systolic pressures in mice via T-cell produced cytokines, Interleukin (IL)-13 and IL-17A. The aim of the current study was to understand how B cell and antibody responses integrate into this T cell cytokine network for the pulmonary hypertension phenotype. Special focus was on antigen-specific IgG1 that is the predominant antibody in the experimental response to antigen and urban ambient PM_2.5. Wild type and B cell-deficient mice were primed with antigen and then challenged with antigen and urban particulate matter and injected with antibodies as appropriate. Our data surprisingly showed that B cells were necessary for the development of increased right ventricular pressures and molecular changes in the right heart in response to sensitization and intranasal challenge with antigen and PM_2.5. Further, our studies showed that both, the increase in right ventricular systolic pressure and right ventricular molecular changes were restored by reconstituting the B cell KO mice with antigen specific IgG1. In addition, our studies identified a critical, non-redundant role of B cells for the IL-17A-directed inflammation in response to exposure with antigen and PM_2.5, which was not corrected with antigen-specific IgG1. In contrast, IL-13-directed inflammatory markers, as well as severe pulmonary arterial remodeling induced by challenge with antigen and PM_2.5 were similar in B cell-deficient and wild type mice. Our studies have identified B cells and antigen specific IgG1 as potential therapeutic targets for pulmonary hypertension associated with immune dysfunction and environmental exposures.

Systemic sclerosis

Systemic sclerosis is a complex autoimmune disease characterized by a chronic and frequently progressive course and by extensive patient-to-patient variability. Like other autoimmune diseases, systemic sclerosis occurs more frequently in women, with a peak of onset in the fifth decade of life. The exact cause of systemic sclerosis remains elusive but is likely to involve environmental factors in a genetically primed individual. Pathogenesis is dominated by vascular changes; evidence of autoimmunity with distinct autoantibodies and activation of both innate and adaptive immunity; and fibrosis of the skin and visceral organs that results in irreversible scarring and organ failure. Intractable progression of vascular and fibrotic organ damage accounts for the chronic morbidity and high mortality. Early and accurate diagnosis and classification might improve patient outcomes. Screening strategies facilitate timely recognition of life-threatening complications and initiation of targeted therapies to halt their progression. Effective treatments of organ-based complications are now within reach. Discovery of biomarkers - including autoantibodies that identify patient subsets at high risk for particular disease complications or rapid progression - is a research priority. Understanding the key pathogenetic pathways, cell types and mediators underlying disease manifestations opens the door for the development of targeted therapies with true disease-modifying potential. For an illustrated summary of this Primer, visit: http://go.nature.com/lchkcA.

Interleukin 13- and interleukin 17A-induced pulmonary hypertension phenotype due to inhalation of antigen and fine particles from air pollution

Pulmonary hypertension has a marked detrimental effect on quality of life and life expectancy. In a mouse model of antigen-induced pulmonary arterial remodeling, we have recently shown that coexposure to urban ambient particulate matter (PM) significantly increased the thickening of the pulmonary arteries and also resulted in significantly increased right ventricular systolic pressures. Here we interrogate the mechanism and show that combined neutralization of interleukin 13 (IL-13) and IL-17A significantly ameliorated the increase in right ventricular systolic pressure, the circumferential muscularization of pulmonary arteries, and the molecular change in the right ventricle. Surprisingly, our data revealed a protective role of IL-17A for the antigen- and PM-induced severe thickening of pulmonary arteries. This protection was due to the inhibition of the effects of IL-13, which drove this response, and the expression of metalloelastase and resistin-like molecule α. However, the latter was redundant for the arterial thickening response. Anti-IL-13 exacerbated airway neutrophilia, which was due to a resulting excess effect of IL-17A, confirming concurrent cross inhibition of IL-13- and IL-17A-dependent responses in the lungs of animals exposed to antigen and PM. Our experiments also identified IL-13/IL-17A-independent molecular reprogramming in the lungs induced by exposure to antigen and PM, which indicates a risk for arterial remodeling and protection from arterial constriction. Our study points to IL-13- and IL-17A-coinduced inflammation as a new template for biomarkers and therapeutic targeting for the management of immune response-induced pulmonary hypertension.

Haemosiderin-laden sputum macrophages for diagnosis in pulmonary veno-occlusive disease

Aims

Pulmonary veno-occlusive disease (PVOD) is a rare condition of pulmonary arterial hypertension (PAH), in which post-capillary veins are affected. Since the therapeutic approach in PVOD differs from other forms of PAH, it is crucial to establish the diagnosis. Due to the fact that affected patients are often hemodynamically unstable, minimal invasive procedures are necessary for the diagnostic work-up. Chronic alveolar haemorrhage has been observed during bronchoalveolar lavage in PVOD cases. This study therefore investigates whether signs of alveolar haemorrhage can also be found in the sputum of these patients.

Methods and Results

Six patients suffering from PVOD were included in this analysis. As controls, patients with idiopathic PAH (n = 11), chronic thromboembolic PH (n = 9) and with sclerodermia-associated PH (n = 10) were assessed. Sputum from every patient was obtained by a non-invasive manner. The amount of haemosiderin-laden macrophages was determined using the Golde score. There were statistically significant more haemosiderin-laden macrophages in the sputum of patients suffering from PVOD as compared to the other groups (P<0.05). Assuming a cut-off of 200 on the Golde score, all of the 6 PVOD patients surpassed this value compared with only 1 out of the 30 cases with precapillary PH. Thus, sensitivity and specificity with respect to the diagnosis of PVOD was 100% and 97%, respectively.

Conclusion

The content of haemosiderin-laden macrophages in the sputum of patients suffering from PVOD is significantly higher as compared to other forms of PH and may be useful in the non-invasive diagnostic work-up of these patients.

Undifferentiated Connective Tissue Disease at risk for systemic sclerosis (SSc) (so far referred to as very early/early SSc or pre-SSc)

In the last few years, a number of studies have been published on a condition characterized by Raynaud's phenomenon (RP) associated with systemic sclerosis (SSc) marker autoantibodies and/or scleroderma-type capillaroscopic abnormalities and referred to as very early/early SSc. The present review is devoted to analyze pathophysiologic, clinical, and evolutive aspects of the condition that would induce to label it as Undifferentiated Connective Tissue Disease at risk for SSc and to split it into 3 subsets (i.e. RP associated to marker autoantibodies and scleroderma-type capillaroscopic abnormalities; RP associated to marker autoantibodies in the absence of scleroderma-type capillaroscopic abnormalities; and RP associated to scleroderma-type capillaroscopic abnormalities without any detectable marker autoantibody), which have been shown to carry different degrees of risk, but not the certainty, to develop overt SSc over time. This nosographic approach is instrumental to plan future studies devoted to investigate validated biomarkers heralding the development of major vascular disease manifestations as well as skin and/or organ fibrosis in patients at risk.

Oxidative stress-dependent activation of collagen synthesis is induced in human pulmonary smooth muscle cells by sera from patients with scleroderma-associated pulmonary hypertension

Pulmonary arterial hypertension is a major complication of systemic sclerosis. Although oxidative stress, intima hyperplasia and a progressive vessel occlusion appear to be clearly involved, the fine molecular mechanisms underpinning the onset and progression of systemic sclerosis-associated pulmonary arterial hypertension remain largely unknown. Here we shows for the first time that an increase of NADPH-derived reactive oxygen species production induced by sera from systemic sclerosis patients with pulmonary arterial hypertension drives collagen type I promoter activity in primary human pulmonary artery smooth muscle cells, suggesting that antioxidant-based therapies should be considered in the treatment of systemic sclerosis-associated vascular diseases.