INTRODUCTION:

Pulmonary arterial hypertension (PAH) is one of the most important and potentially life-threatening disorders of the pulmonary circulation and is defined as a systolic pulmonary artery pressure of > 35 mm Hg or, alternatively, as a mean pulmonary artery pressure of > 25 mm Hg at rest or > 30 mm Hg with exertion¹.Bone morphogenetic protein receptor II (BMPR2) is a receptor for the bone morphogenetic proteins (members of the transforming growth factor-β super family),

This group of homologous signaling proteins has a diverse number of functions and plays an important role in embryogenesis, organogenesis, cell proliferation and stem cell differentiation, mutations in the BMPR2 gene cause loss of function and reduced signaling downstream of the receptor, subsequently BMPR2 mutations have been identified in apparently sporadic cases of idiopathic PAH with a frequency ranging from 11%9 to 40% ²also the BMPs are regulators of animal development³. BMPs were first identified in bone matrix^,4, they were shown to be important in embryonic development ⁵.

BMP2 is made up of 103 residues, The secondary structure is primarily beta sheets with 49 residues forming 10 strands These strands form a defining structural feature of two finger-like double-stranded beta-sheets and this protein contains 14% helical structure, concentrated as a four-turn helix perpendicular to the beta-sheets, dimerization createsa hydrophobic core between the monomers that stabilizes the molecule⁶.

MATERIALS AND METHODS:

Subjects (Patients and apparently healthy groups):

The current study included fifty six (56) patients suffered from pulmonary artery hypertension.

The Patients are divided into subgroups according to gender, ages, types, smoking, types of secondary pulmonary artery hypertension, body mass index and grades.

The samples were collected from AL-Najaf AL-Ashraf / AL-Sadder Teaching Hospital during the period from September 2016 to February 2017. The patients were taken from the Echocardiography unit and Najaf Cardiac Centre. The control group was composed of thirty four (34) appear healthy aged (30-39) years. A full history of each subjects was recorded, they should have no history of heart disease , PAH and diabetes .The control group also entered to Echocardiography unit to evaluated the presence of pulmonary arterial hypertension or any disease related with PAH.

Symptoms and diagnosis of pulmonary arterial hypertension patients:

The symptoms of pulmonary arterial hypertension include; Shortness of breath, chest pain and irregular heartbeat, swelling in the limbs and blue lips, fatigue and dizziness.

The pulmonary arterial hypertension were diagnosed depend on specialized physician and cardiologist; Echocardiograph was used to estimate pulmonary arterial pressure and to assess for right arterial enlargement systolic or non-systolic dysfunction, vulvular disease, congenital heart disease also respiratory dysfunction by chronic obstructive pulmonary disease (COPD).

Collection of blood samples:

Five milliliters of venous blood were drown from pulmonary arterial hypertension patients and healthy group among 9-11 A.M from antecubital venipuncture using a disposable needle and plastic syringes blood was left at room temperature for 10 minutes to clot in the gel tube The serum was isolated after centrifugation at 3000 R.P.M for 15 minutes and then serum was separated and transported into new disposable tubes and stored at -20ᴼ C

Biochemical markers:

Determination of serum BMPR2 level:

Specific kit for measurement human CYP-A concentrations in serum was supplied by Elabscience Biotechnology Co., Ltd. A Catalog No: E-EL-H1934.

Statistical Analysis:

The data of present study were articulated as (Mean±StandardError), the statistical analysis (descriptive statistics, and Graph pad prism, when Pvalue<0.05 was statistically asignificant⁷.

RESULTS:

Serum Bone morphogenetic protein receptor IIlevel

In Control and patients groups:

The results in figure (4.1) indicate a significant decrease (P<0.05) in serum Bone morphogenetic protein receptor II (BMPR2) level in pulmonary arterial hypertension patients 2.495 ± 0.221 ng/ml in comparing with control (healthy) group 6.838 ± 0.372 ng/ml.

P – value = 1.27E- 17

Figure (1): Bone morphogenetic protein receptor II level in pulmonary arterial hypertension patients and control groups.

(*)Statistically significant differences (p<0.05) between patients and control groups.

Bone morphogenetic protein receptor II level in pulmonary arterial hypertension patients according to gender

The results of figure (2) indicate a significant increase (P<0.05) in serum Bone morphogenetic protein receptor II (BMPR2) level in pulmonary arterial hypertension patients (male) 3.943 ± 0.321 comparing with female 2.419 ± 0.533 .

P – value = 0.0118

Figure (2): Bone morphogenetic protein receptor II level according to gender.

(*)Statistically significant differences (p<0.05) between male and female groups.

Bone morphogenetic protein receptor II level according to types of pulmonary artery hypertension.

The results of figure (3) indicate a significant increase (P<0.05) in secondary pulmonary arteries hypertension 3.106 ± 0.335 ng/ml comparing with primary type 1.031 ± 0.141 ng/ml,

P – value = 2.75E – 05.

Figure (3): Bone morphogenetic protein receptor II level according to types of pulmonary artery hypertension (PAH).

(*)Statistically significant differences (p<0.05) between primary and secondary types.

Bone morphogenetic protein receptor II level according to Smoker and non Smoker:

The results of figure (4) reveal no significant differences (p> 0.05) in serum Bone morphogenetic protein receptor II level between pulmonary arterial hypertension patients (Smoker) 3.136 ± 0.352 ng/ml and (non Smoker) 2.844 ± 0.411 ng/ml.

P – value = 0.5969

Figure (4): Bone morphogenetic protein receptor II level according to Smoker and non Smoker pulmonary arterial hypertension.

Bone morphogenetic protein receptor II level according to the types of secondary pulmonary arterial hypertension:

The results of figure (.5) shows there is significant increase (p<0.05) in serum Bone morphogenetic protein receptor II level in patients of vulvular heart disease 5.087 ±0.881 ng/ml comparing with congenital heart disease and Chronic obstructive pulmonary disease while there is no significant between congenital heart disease and Chronic obstructive pulmonary disease .

Figure (5):Bone morphogenetic protein receptor II level according to the types of secondary pulmonary arterial hypertension.

The different letters refer to significant difference at level (P<0.05), The same letters refer to no significant differences.

Bone morphogenetic protein receptor II level according to ages:

The results of figure (6) shows there is significant increase (p<0.05) in serum Bone morphogenetic protein receptor II level in patients at ages (60 – 69 year)3.875 ± 0.529 ng/ml comparing with patients at ages (30 – 39 year) 1.017 ± 0.171 ng/ml, while there is no significant between patients at ages (60 – 69 year)3.875 ± 0.529 ng/ml, (40 – 49 year) 3.754 ±0.582 ng/ml and (50 – 59 year) 3.550 ±0.472 ng/ml.

Figure (6): Bone morphogenetic protein receptor II level according to ages.

The different letters refer to significant difference at level (P<0.05), The same letters refer to no significant differences.

Bone morphogenetic protein receptor II level according to grades:

The results of figure (7) shows there is significant increase (p<0.05) in serum Bone morphogenetic protein receptor II level in patients at (moderate) 3.935± 0.546 ng/ml comparing with (severe)1.471±0.260while there is no significant between (mild 3.537 ± 0.442 and moderate 3.935± 0.546 ng/ml.

Figure (7): Bone morphogenetic protein receptor II level according to grades.

The different letters refer to significant difference at level (P<0.05), The same letters refer to no significant differences.

DISCUSSION:

The present study indicate a significant decrease (p>0.05) in serum level BMPR2 in PAH in comparison of healthy group. ⁸Study of suggested that deletion of BMPR2 lead to attenuated of BMP signaling in the endothelium and cause of pulmonary vascular remolding and spontaneous development of pulmonary artery hypertension in mice. The antagonistic effect of Gremlin have been demonstrated in the lung recently and showed that gremlin can bind with BMPR2 and preventing to produce sufficient protein and therefore the efficient BMP protein signalingcan be inhibited in embryonic lung⁹. Previous studies demonstrated the antagonistic effect of gremlin directly with the cell surface protein such as slite protein or heparan-sulfate proteoglycansand therefore lead to altered the cell functions and the signaling of BMP was inhibited¹⁰. Some studies have been suggested that low expression of BMPR2 due to specific mutations that cause attenuation of normal cellular response to (BMPs) in the lung resulting in the pathogenesis of pulmonary arterial hypertension¹¹. Study of ¹²and ¹³ have been showed that a BMPs signals are a homeostatic roles in the lung also the insufficient or depression of noggin protein lead to de – repression of BMP signaling because the noggin is a highly broad spectrum endogenous protein antagonists to BMP.

The current results also indicated in a significant decrease (p˂0.05) in BMPR2 level in female patients than male. The study of ¹⁴ have been indicated that a high prevalence of PAH in female than male and another study demonstrated that found of deletion in X- chromosome of BMPR2 as a genetic cause of PAH. The study of¹⁵ have been indicated the role of estrogen in women during pregnancy, contraceptive and after menopause in aggravate PAH. The decrement of BMPR2 level in primary arterial hypertension than secondary arterial hypertension reflected that most of familial (PAH) that resulted from mutation in BMPR2 and reduced of expression were concentrated in these patients¹⁶. The smokers PAH patients were significantly decrease in BMPR2 than non-smoker patients .Several studies have been concentrated on the effect of smoking on the expression of BMPR2 level and found that an association between hypoxia induced pathogenesis of PAH may lead to altered in the signaling of BMPR2 level and cell function. The results also revealed significant decrease (p˂0.05) in BMPR2 in COPD and congenital heart disease in comparing with vulvular heart disease. Many researchers have been showed that animals with congenital absence of T-cells and vascular injury of the lung lead to macrophage infiltrate due to defect in cell surface and BMP signaling and low expression of BMPR2¹⁷. In a study of¹⁸ were suggested that a mutation in smad 6 gene in congenital cardiovascular disease lead to inhibit BMP-induced osteogenic differentiation. The hypoxia of COPD patients may play important roles in reduced of BMP signaling and altered cell membrane surfaces capacity and defects in BMPs receptors^{19 .}The present study demonstrated that significant decrease in BMPR2 in Age (30 – 39) year in comparing with other ages in patients with PAH. The study of ²⁰have been demonstrated that primary PAH patient with younger aged were highly prevalence due to mutation in Gremlin 1 and BMPRII that lead to decrease in BMPs signaling. The results showed a significant decrease (p˂0.05) in BMPR2 in severe PAH patients in comparing with other groups. The study of²⁰have been showed that reduction in BMPR2 function in severe PAH patients especially in the endothelium lead to enhance the apoptosis and ingress other serum factors, which increase smooth muscle proliferation, myofibroblast, proliferation, matrix and vascular remodeling changes therefore the dysfunction or abnormal pathway of BMPRII play important roles in homeostasis and pathogenesis of PAH.

REFERENCES:

1 McGoon, M.; Gutterman, D.; and Steen, V.; et al (2004). Screening, early detection, and diagnosis of pulmonary arterial hypertension: ACCP evidence-based clinical practice guidelines. Chest.,126:14S-34S.

2 Morisaki, H.; Nakanishi, N.; Kyotani, S.; and Takashima, A.; et al (2004). BMPR2 mutations found in Japanese patients with familial and sporadic primary pulmonary hypertension. Hum Mutat., 23: 632.

3 Nohe, A.; et al (2002). The mode of bone morphogeneticprotein (BMP) receptor oligomerization determines differentBMP-2 signaling pathways. Journal of Biological Chemistry. 277:5330-5338.

4 Ducy, P.; and Karsenty, G.; (2000). The family of bone morphogenetic proteins. Kidney International. 57: 2207-2214.

5 Beppu, H.; et al (2000). BMP type II receptor is required for gastrulation and early development of mouse embryos. Developmental Biology. 221: 249-258.

6 Weber, C.; Zernecke, A.; and Libby, P.; (2008).The multifaceted contributions of leukocyte subsets to atherosclerosis: lessons from mouse models. Nat. Rev. Immunol., 8:802-815.

7 Al-Rawi, K. (2000). Entrance to the Statistics. Second edition. Faculty of Agriculture and Forestry, University of Mosul.

8 Lu, M.M.; Yang, H.; Zhang, L.; and Shu, W.; et al (2001). The bone morphogenic protein antagonist gremlin regulates proximal-distal patterning of the lung. DevDyn.222:667–680.

9 Sun, J.; Zhuang, F.F.; Mullersman, J.E.; and Chen, H.; et al (2006). BMP4 activation and secretion are negatively regulated by an intracellular gremlin-BMP4 interaction. J. Biol. Chem., 281:29349–29356.

10 Chen, B.; Blair, D.G.; Plisov, S.; and Vasiliev, G.; et al (2004). Bonemorphogenetic protein antagonists Drm/Gremlin and Dan interact with Slits and act as negative regulators of monocyte chemotaxis. J. Immunol. 173:5914–5917.

11 Wagner, T.U.; (2007). Bone morphogenetic protein signaling in stem cells: onesignal, many consequences. FEBS. J, 274:2968–2976.

12 Sountoulidis, A.; Stavropoulos, A.; Giaglis, S.; and Apostolou, E.; et al (2012).Activation of the canonical Bone Morphogenetic Protein (BMP) pathway during lung morphogenesis and adult lung tissue repair. PLoS One.,7:e41460

13 Bartram, U.; and Speer, C.P.;(2004).The role of transforming growth factor beta in lung development and disease. Chest.125:754–65.

14 McLaughlin, V.V.; Archer, S.L.; and Badesch, D. B.; et al (2009). ACCF/AHA expert consensus document on pulmonary hypertension. Circulation., 119(16):2276.

15 Austin, E.D.; Cogan, J.D.; West, J.D.; and Hedges, L.K.; et al (2009). Alterations in oestrogen metabolism: implications for higher penetrance of familial pulmonary arterial hypertension in females. Eur. Respir. J.,34(5):1093–1099.

16 Nolan, K.; Kattamuri, C.; Luedeke, D.M.; and Deng, X.; et al( 2013). Structure of protein related to Dan and Cerberus: insights into the mechanism of bone.12874-59874.

17 Soon, E.; Holmes, A.M.; and Treacy, C. M.; et al (2010). Elevated levels of inflammatory cytokines predict survival in idiopathic and familial pulmonary arterial hypertension. Circulation., 122: 920–927.

18 Tan, H.L.; Glen, E.; Topf, A.; and Hall, D.; et al (2012). Non-synonymous variants in the SMAD6 gene predispose to congenital cardiovascular malformation. Hum Mutat. 12(4):564-678.

19 Eric, D.; John, A.; James, E.; and Loyd; et al (2009). Genetics of Pulmonary Arterial Hypertension. Semin.Respir. Crit. Care. Med., 30(4): 386-398.

20 Thompson, J.R.; Machado, R.D.; and Pauciulo, M.W.; (2000). Sporadic primary pulmonary hypertension is associated with germline mutations of the gene encoding BMPR-II, a receptor member of the TGF-β family. J. Med. Genet.,37:741–5.

Received on 11.05.2017 Modified on 14.07.2017

Research J. Pharm. and Tech. 2017; 10(8): 2614-2618.

DOI: 10.5958/0974-360X.2017.00464.4