Antenatal BAY 41-2272 reduces pulmonary hypertension in the rabbit model of congenital diaphragmatic hernia

Increased Elastase and Matrix Metalloproteinase Levels in the Pulmonary Arteries of Infants With Congenital Diaphragmatic Hernia

BACKGROUND

Pulmonary vascular disease (PVD) complicated with pulmonary hypertension (PH) is a leading cause of mortality in congenital diaphragmatic hernia (CDH). Unfortunately, CDH patients are often resistant to PH therapy. Using the nitrogen CDH rat model, we previously demonstrated that CDH-associated PVD involves an induction of elastase and matrix metalloproteinase (MMP) activities, increased osteopontin and epidermal growth factor (EGF) levels, and enhanced smooth muscle cell (SMC) proliferation. Here, we aimed to determine whether the levels of the key members of this proteinase-induced pathway are also elevated in the pulmonary arteries (PAs) of CDH patients.

METHODS

Neutrophil elastase (NE), matrix metalloproteinase-2 (MMP-2), epidermal growth factor (EGF), tenascin-C, and osteopontin levels were assessed by immunohistochemistry in the PAs from the lungs of 11 CDH patients and 5 normal age-matched controls. Markers of proliferation (proliferating cell nuclear antigen (PCNA)) and apoptosis (cleaved (active) caspase-3) were also used.

RESULTS

While expressed by both control and CDH lungs, the levels of NE, MMP-2, EGF, as well as tenascin-C and osteopontin were significantly increased in the PAs from CDH patients. The percentage of PCNA-positive PA SMCs were also enhanced, while those positive for caspase-3 were slightly decreased.

CONCLUSIONS

These results suggest that increased elastase and MMPs, together with elevated tenascin-C and osteopontin levels in an EGF-rich environment may contribute to the PVD in CDH infants. The next step of this study is to expand our analysis to a larger cohort, and determine the potential of targeting this pathway for the treatment of CDH-associated PVD and PH.

TYPE OF STUDY

Therapeutic.

LEVEL OF EVIDENCE

LEVEL III.

Cannabidiol alleviates right ventricular fibrosis by inhibiting the transforming growth factor β pathway in monocrotaline-induced pulmonary hypertension in rats

Cannabidiol (CBD) is a non-intoxicating compound of Cannabis with anti-fibrotic properties. Pulmonary hypertension (PH) is a disease that can lead to right ventricular (RV) failure and premature death. There is evidence that CBD reduces monocrotaline (MCT)-induced PH, including reducing right ventricular systolic pressure (RVSP), vasorelaxant effect on pulmonary arteries, and decreasing expression of profibrotic markers in the lungs. The aim of our study was to investigate the effect of chronic administration of CBD (10 mg/kg daily for 21 days) on profibrotic parameters in the RVs of MCT-induced PH rats. In MCT-induced PH, we found an increase in profibrotic parameters and parameters related to RV dysfunction, i.e. plasma pro-B-type natriuretic peptide (NT-proBNP), cardiomyocyte width, interstitial and perivascular fibrosis area, amount of fibroblasts and fibronectin, as well as overexpression of the transforming growth of factor β1 (TGF-β1), galectin-3 (Gal-3), suppressor of mothers against decapentaplegic 2 (SMAD2), phosphorylated SMAD2 (pSMAD2) and alpha-smooth muscle actin (α-SMA). In contrast, vascular endothelial cadherin (VE-cadherin) levels were decreased in the RVs of MCT-induced PH rats. Administration of CBD reduced the amount of plasma NT-proBNP, the width of cardiomyocytes, the amount of fibrosis area, fibronectin and fibroblast expression, as well as decreased the expression of TGF-β1, Gal-3, SMAD2, pSMAD2, and increased the level of VE-cadherin. Overall, CBD has been found to have the anti-fibrotic potential in MCT-induced PH. As such, CBD may act as an adjuvant therapy for PH, however, further detailed investigations are recommended to confirm our promising results.

CONGENITAL DIAPHRAGMATIC HERNIA INCREASES THE SENSITIVITY OF PULMONARY ARTERIES TO NITRIC OXIDE

Left congenital diaphragmatic hernia (CDH) can lead to pulmonary arteries abnormalities in the contralateral and ipsilateral sides of the diaphragm. Nitric oxide (NO) is the main therapy used to attenuate the vascular effects of CDH, but it is not always effective. We hypothesized that the left and right pulmonary arteries do not respond similarly to NO donors during CDH. Therefore, vasorelaxant responses of the left and right pulmonary arteries to sodium nitroprusside (SNP, a NO donor) were determined in a rabbit experimental model of left CDH. CDH was surgically induced in the fetuses of rabbits on the 25^th day of pregnancy. On the 30^th day of pregnancy, a midline laparotomy was performed to access the fetuses. The fetuses' left and right pulmonary arteries were isolated and mounted in myograph chambers. Vasodilation was evaluated by cumulative concentration-effect curves to SNP. Protein expression of guanylate cyclase isoforms (GCα, GCβ) and the α isoform of cGMP-dependent protein kinase 1 (PKG1α), and the concentration of NO and cGMP were determined in the pulmonary arteries. The left and right pulmonary arteries of newborns with CDH exhibited increased vasorelaxant responses to SNP (i.e. the potency of SNP was increased) compared to the control group. GCα, GCβ, and PKG1α expression were decreased, while NO and cGMP concentrations were increased in the pulmonary arteries of newborns with CDH compared to the control group. The increased cGMP mobilization may be responsible for the increased vasorelaxant responses to the SNP in the pulmonary arteries during left CDH.

Emerging antenatal therapies for congenital diaphragmatic hernia-induced pulmonary hypertension in preclinical models

Congenital diaphragmatic hernia (CDH)-related deaths are the largest contributor to in-hospital neonatal deaths in children with congenital malformations. Morbidity and mortality in CDH are directly related to the development of pulmonary hypertension (PH). Current treatment consists of supportive measures. To date, no pharmacotherapy has been shown to effectively reverse the hallmark finding of pulmonary vascular remodeling that is associated with pulmonary hypertension in CDH (CDH-PH). As such, there is a great need for novel therapies to effectively manage CDH-PH. Our review aims to evaluate emerging therapies, and specifically focuses on those that are still under investigation and not approved for clinical use by the Food and Drug Administration. Therapies were categorized into antenatal pharmacotherapies or antenatal regenerative therapies and assessed on their method of administration, safety profile, the effect on pulmonary vascular pathophysiology, and overall efficacy. In general, emerging antenatal pharmaceutical and regenerative treatments primarily aim to alleviate pulmonary vascular remodeling by restoring normal function and levels of key regulatory factors involved in pulmonary vascular development and/or in promoting angiogenesis. Overall, while these emerging therapies show great promise for the management of CDH-PH, most require further assessment of safety and efficacy in preclinical models before translation into the clinical setting. IMPACT: Emerging antenatal therapies for congenital diaphragmatic hernia-induced pulmonary hypertension (CDH-PH) show promise to effectively mitigate vascular remodeling in preclinical models. Further investigation is needed in preclinical and human studies to evaluate safety and efficacy prior to translation into the clinical arena. This review offers a comprehensive and up-to-date summary of emerging therapies currently under investigation in experimental animal models. There is no cure for CDH-PH. This review explores emerging therapeutic options for the treatment of CDH-PH and evaluates their impact on key molecular pathways and clinical markers of disease to determine efficacy in the preclinical stage.

Pulmonary hypertension secondary to congenital diaphragmatic hernia: factors and pathways involved in pulmonary vascular remodeling

Congenital diaphragmatic hernia (CDH) is a severe birth defect that is characterized by pulmonary hypoplasia and pulmonary hypertension (PHTN). PHTN secondary to CDH is a result of vascular remodeling, a structural alteration in the pulmonary vessel wall that occurs in the fetus. Factors involved in vascular remodeling have been reported in several studies, but their interactions remain unclear. To help understand PHTN pathophysiology and design novel preventative and treatment strategies, we have conducted a systematic review of the literature and comprehensively analyzed all factors and pathways involved in the pathogenesis of pulmonary vascular remodeling secondary to CDH in the nitrofen model. Moreover, we have linked the dysregulated factors with pathways involved in human CDH. Of the 358 full-text articles screened, 75 studies reported factors that play a critical role in vascular remodeling secondary to CDH. Overall, the impairment of epithelial homeostasis present in pulmonary hypoplasia results in altered signaling to endothelial cells, leading to endothelial dysfunction. This causes an impairment of the crosstalk between endothelial cells and pulmonary artery smooth muscle cells, resulting in increased smooth muscle cell proliferation, resistance to apoptosis, and vasoconstriction, which clinically translate into PHTN.

Elastase and matrix metalloproteinase activities are associated with pulmonary vascular disease in the nitrofen rat model of congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Pulmonary vascular disease (PVD) is a leading cause of congenital diaphragmatic hernia (CDH) mortality. Progression of PVD involves extracellular matrix remodeling by elastases and matrix metalloproteinases (MMP), concomitant with proliferation of smooth muscle cells in a growth factor-enriched environment. Blockade of this pathway reversed primary pulmonary hypertension and improved survival. This study was designed to determine whether a similar pathway is induced in PVD secondary to CDH.

METHODS

Fetal rats exposed to nitrofen at gestational day 9 developed left-sided CDH and were compared at term to their non-CDH littermates by assessing histologic and biochemical features of PVD.

RESULTS

Rats with CDH displayed right ventricle hypertrophy, increased pulmonary artery medial wall thickness and muscularization, and decreased lumen size. As revealed by in situ zymography and immunohistochemistry, this was associated with an induction of elastolytic and MMP activities as well as an elevation of epidermal growth factor and osteopontin levels in the diseased lung vasculature.

CONCLUSIONS

CDH-associated PVD involves an induction of elastase and MMP activities and increased osteopontin deposition in an epidermal growth factor-rich environment. Inhibition of this pathway may thus represent a novel therapeutic approach for the treatment of CDH-associated PVD.

LEVEL OF EVIDENCE

Level I (Basic Science Study).

Cord blood-derived endothelial colony-forming cell function is disrupted in congenital diaphragmatic hernia

Vascular growth is necessary for normal lung development. Although endothelial progenitor cells (EPCs) play an important role in vascularization, little is known about EPC function in congenital diaphragmatic hernia (CDH), a severe neonatal condition that is associated with pulmonary hypoplasia. We hypothesized that the function of endothelial colony-forming cells (ECFCs), a type of EPC, is impaired in CDH. Cord blood (CB) was collected from full-term CDH patients and healthy controls. We assessed CB progenitor cell populations as well as plasma vascular endothelial growth factor (VEGF) and stromal cell-derived factor 1α (SDF1α) levels. CB ECFC clonogenicity; growth kinetics; migration; production of VEGF, SDF1α, and nitric oxide (NO); vasculogenic capacity; and mRNA expression of VEGF-A, fms-related tyrosine kinase 1 (FLT1), kinase insert domain receptor (KDR), nitric oxide synthase (NOS) 1-3, SDF1, and chemokine (C-X-C motif) receptor 4 (CXCR4) were also assessed. Compared with controls, CB ECFCs were decreased in CDH. CDH ECFCs had reduced potential for self-renewal, clonogenicity, proliferation, and migration. Their capacity for NO production was enhanced but their response to VEGF was blunted in CDH ECFCs. In vivo potential for de novo vasculogenesis was reduced in CDH ECFCs. There was no difference in CB plasma VEGF and SDF1α concentrations, VEGF and SDF1α production by ECFCs, and ECFC mRNA expression of VEGF-A, FLT1, KDR, NOS1-3, SDF1, and CXCR4 between CDH and control subjects. In conclusion, CB ECFC function is disrupted in CDH, but these changes may be caused by mechanisms other than alteration of VEGF-NO and SDF1-CXCR4 signaling.