The Roles of S100A4 and the EGF/EGFR Signaling Axis in Pulmonary Hypertension with Right Ventricular Hypertrophy

Pulmonary hypertension (PH) is characterized by increased pulmonary arterial pressure caused by the accumulation of mesenchymal-like cells in the pulmonary vasculature. PH can lead to right ventricular hypertrophy (RVH) and, ultimately, heart failure and death. In PH etiology, endothelial-to-mesenchymal transition (EndMT) has emerged as a critical process governing the conversion of endothelial cells into mesenchymal cells, and S100A4, EGF, and EGFR are implicated in EndMT. However, a potential role of S100A4, EGF, and EGFR in PH has to date not been elucidated. We therefore quantified S100A4, EGF, and EGFR in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH) and idiopathic pulmonary arterial hypertension (iPAH). To determine specificity for unilateral heart disease, the EndMT biomarker signature was further compared between PH patients presenting with RVH and patients suffering from aortic valve stenosis (AVS) with left ventricular hypertrophy. Reduced S100A4 concentrations were found in CTEPH and iPAH patients with RVH. Systemic EGF was increased in CTEPH but not in iPAH, while AVS patients displayed slightly diminished EGF levels. EGFR was downregulated in all patient groups when compared to healthy controls. Longitudinal data analysis revealed no effect of surgical therapies on EndMT markers. Pulmonary thrombo-endarterectomized samples were devoid of S100A4, while S100A4 tissue expression positively correlated with higher grades of Heath–Edwards histopathological lesions of iPAH-derived lung tissue. Histologically, EGFR was not detectable in CTEPH lungs or in iPAH lesions. Together, our data suggest an intricate role for S100A4 and EGF/EGFR in PH with right heart pathology.

Congestive Hepatopathy Secondary to Right Ventricular Hypertrophy Related to Monocrotaline-Induced Pulmonary Arterial Hypertension

Heart dysfunction and liver disease often coexist. Among the types of cardiohepatic syndrome, Type 2 is characterized by the chronic impairment of cardiac function, leading to chronic liver injury, referred to as congestive hepatopathy (CH). In this study, we aimed to establish a rat model of CH secondary to right ventricular hypertrophy (RVH) related to monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH). Fifty male Wistar rats were divided into four groups and randomly assigned to control and experimental groups. Three experimental groups were submitted to intraperitoneal MCT inoculation (60 mg/kg) and were under its effect for 15, 30 and 37 days. The animals were then sacrificed, obtaining cardiac and hepatic tissues for anatomopathological and morphometric analysis. At macroscopic examination, the livers in the MCT groups presented a nutmeg-like appearance. PAH produced marked RVH and dilatation in the MCT groups, characterized by a significant increase in right ventricular free wall thickness (RVFWT) and chamber area. At histological evaluation, centrilobular congestion was the earliest manifestation, with preservation of the hepatocytes. Centrilobular hemorrhagic necrosis was observed in the groups exposed to prolonged MCT. Sinusoidal dilatation was markedly increased in the MCT groups, quantified by the Sinusoidal Lumen Ratio (SLR). The Congestive Hepatic Fibrosis Score and the Centrilobular Fibrosis Ratio (CFR) were also significantly increased in the MCT30 group. Hepatic atrophy, steatosis, apoptotic bodies and, rarely, hydropic swelling were also observed. SLR correlated strongly with CFR and RVFWT, and CFR correlated moderately with RVFWT. Our rat model was able to cause CH, related to monocrotaline-induced PAH and RVH; it was feasible, reproducible, and safe.

Percutaneous balloon pulmonary valvuloplasty in a pregnant woman with severe pulmonary valve restenosis

A 34-year-old woman, a known case of valvular heart disease, post balloon pulmonary valvuloplasty done 8 years ago during her first pregnancy, presented with progressive exertional breathlessness with New York Heart Association class III symptoms in her third trimester of pregnancy. On examination, she had features of right heart failure. ECG showed right axis deviation, right ventricular hypertrophy with strain pattern. Transthoracic echocardiography showed severe pulmonary valve stenosis, right ventricular hypertrophy, right ventricular and atrial dilatation with reduced right ventricular function. As the patient was symptomatic, she underwent percutaneous balloon pulmonary valvuloplasty. The procedure was successful with a significant reduction in the pulmonary valve gradient and the patient was discharged in stable condition with reduced symptoms. The timely intervention of the valvular stenotic lesion in pregnancy reduces the mortality risk to both the mother and the fetus.

Increased incidence of Persistent Pulmonary Hypertension of the Newborn following third trimester maternal COVID-19 infection

Background Novel coronavirus (COVID-19) has been a world concern since December 2019. The knowledge about vertical transmission and fetal morbidity and mortality from maternal COVID-19 infection is limited. We detected an increase in the number of cases of term and near-term neonates with persistent pulmonary hypertension (PPHN) during the COVID-19 pandemic in 2020. Methods and results We collected data on all newborns with PPHN born between 2018 and 2020. We excluded premature infants (<34+0 weeks) and infants with other significant pathology or genetic syndromes. Compared to 5 cases of PPHN of 22930 live births in 2018, and 6 cases of PPHN of 22270 live births in 2019 (2-year average 0.02%, 95% CI 0.013%-0.043%), there were 16 PPHN cases from 22323 live births in 2020 (0.07%, 95% CI 0.044%-0.12%), a 3 fold increase (p<0.01). We report 5 cases of term and near-term neonates born to mothers who had highly suspected (2) and PCR proven (3) COVID-19 infection during the third trimester of pregnancy, who presented with PPHN during COVID-19 pandemic in 2020. All had otherwise unexplained pulmonary hypertension, right ventricular hypertrophy (RVH) and dilatation. Two patients needed endotracheal intubation, one was supported by nasal continuous positive airway pressure (CPAP) without intubation, two needed O2 support by nasal cannula only ant two newborns (one of them was intubated) needed Nitric oxide (NO) as pulmonary vasodilator therapy. No patient required Extracorporeal membrane oxygenation (ECMO) or died, and no prolonged residual cardiovascular or pulmonary morbidity was recorded during a median follow up of 4.8 months (range 4–6 months). Conclusions The increase in the incidence of PPHN during the COVID-19 pandemic, and the cases presented, suggest an intrauterine effect of maternal COVID-19 infection on the fetal pulmonary circulation. It is possible that the maternal infection affected the fetal pulmonary vascular resistance, or altered the normal decline in the resistance after birth. The right ventricular hypertrophy and dilatation with reduced function may be secondary to this hypothetical increased afterload or a direct effect of the infection. Further studies are warranted to elucidate the pathogenesis and clinical implications of this phenomenon. FUNDunding Acknowledgement Type of funding sources: None.

Parathyroid hormone affects right heart hemodynamics and exacerbates pulmonary hypertension

Background Pulmonary hypertension (PH) is characterized by increased pulmonary artery pressure and develops right heart failure. Parathyroid hormone (PTH) is secreted from parathyroid gland and regulates a calcium homeostasis. Recent studies have suggested that PTH also acts on the cardiovascular system and affects cardiovascular prognosis. We hypothesized that PTH would play a role in the pathogenesis of PH. Purpose This study aimed to investigate the effect of PTH on pulmonary hemodynamics. Method We measured serum PTH levels in patients who were suspected of PH and underwent right heart catheter examination. We used two types of PH animal models, hypoxia (Hx)-induced PH mouse model and Sugen/hypoxia (SuHx)-induced PH rat model. Hx mice were administered PTH daily for 3 weeks. SuHx rats underwent parathyroidectomy, after which they received SuHx treatment for 10weeks. We measured physical data and right ventricular systolic pressure (RVSP) in these models. We cultured pulmonary artery smooth muscle cell (PASMC) treated with PTH to analyze cell signaling, proliferation and migration. Result We enrolled 20 participants. PTH concentration was significantly correlated with mean pulmonary artery pressure (r=0.58, p=0.006) as well as with pulmonary vascular resistance (r=0.61, p=0.04). Receiver operating characteristic curve displayed a cut-off PTH level of 48.0pg/ml that offered optimal differentiation between patients with and without PH (100% sensitivity, 73% specificity). PTH treatment exacerbated right ventricular hypertrophy and increased RVSP (33.6mmHg vs. 48.2mmHg) in Hx mice compared with non-treated Hx mice (Figure 1). Conversely, parathyroidectomy significantly attenuated right ventricular hypertrophy and reduced RVSP (54.2mmHg vs. 29.3mmHg) in SuHx rats compared with sham-operated SuHx rats. PTH promoted migration and proliferation through ERK signaling in PASMC. Conclusion Our clinical and experimental data demonstrated a critical role of PTH in the development of PH and suggested that PTH would be a novel therapeutic target for PH treatment. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grant-in-Aid for Young Scientists Figure 1. PTH treatment exacerbated RVSP

The pan-PPAR agonist lanifibranor reduces development of lung fibrosis and attenuates cardiorespiratory manifestations in a transgenic mouse model of systemic sclerosis

Background The TβRII∆k-fib transgenic (TG) mouse model of scleroderma replicates key fibrotic and vasculopathic complications of systemic sclerosis through fibroblast-directed upregulation of TGFβ signalling. We have examined peroxisome proliferator-activated receptor (PPAR) pathway perturbation in this model and explored the impact of the pan-PPAR agonist lanifibranor on the cardiorespiratory phenotype. Methods PPAR pathway gene and protein expression differences from TG and WT sex-matched littermate mice were determined at baseline and following administration of one of two doses of lanifibranor (30 mg/kg or 100 mg/kg) or vehicle administered by daily oral gavage up to 4 weeks. The prevention of bleomycin-induced lung fibrosis and SU5416-induced pulmonary hypertension by lanifibranor was explored. Results Gene expression data were consistent with the downregulation of the PPAR pathway in the TβRII∆k-fib mouse model. TG mice treated with high-dose lanifibranor demonstrated significant protection from lung fibrosis after bleomycin and from right ventricular hypertrophy following induction of pulmonary hypertension by SU5416, despite no significant change in right ventricular systolic pressure. Conclusions In the TβRII∆k-fib mouse strain, treatment with 100 mg/kg lanifibranor reduces the development of lung fibrosis and right ventricular hypertrophy induced by bleomycin or SU5416, respectively. Reduced PPAR activity may contribute to the exaggerated fibroproliferative response to tissue injury in this transgenic model of scleroderma and its pulmonary complications.