Matrix Metalloproteinase-9 Is a Predictive Factor for Systematic Hypertension and Heart Dysfunction in Patients with Obstructive Sleep Apnea Syndrome.

Qinglai Tang,Bin Wang,Shuhui Wang,Jiajia Liu,Shisheng Li

doi:10.1155/2018/1569701

Abstract

Patients with obstructive sleep apnea syndrome (OSAS) showed higher prevalence in cardiovascular diseases due to aberrant hypoxia and oxidative stress. However, not all OSAS patients end up with cardiovascular disorders, and identification of novel biomarker will be invaluable for differentiating patients at risk. Here we tested the serum matrix metalloproteinase-9 (MMP-9) levels in 47 untreated OSAS patients and found that the MMP-9 level was positively correlated with severity of OSAS, which was consistent with hypoxia degree and duration. Besides, the MMP-9 level was higher in patients complicated with systematic hypertension (P < 0.001). Furthermore, we selected those OSAS patients without any cardiovascular dysfunction (n = 35) and followed up for up to five years. By the end of follow-up, 12 patients had hypertension onset and 3 patients had left ventricular hypertrophy. By analyzing the clinical outcomes with MMP-9 expression, we demonstrated that high serum MMP-9 in OSAS patients was a risk factor for occurrence of cardiovascular diseases. In addition, we cultured the vascular endothelial cells (VEC) from rat aorta in hypoxia condition to investigate whether MMP-9 was elevated due to hypoxia in OSAS patients. Cellular results revealed that the expression, secretion, and activity of MMP-9 were all upregulated by hypoxia and can cleave the beta2-adrenergic receptor (β2AR) on VEC surface. Our results not only determined MMP-9 as a risk factor for cardiovascular diseases in OSAS patients, but also showed the possible involvement of hypoxia-MMP-9-β2AR signaling axis.

Highlights

Apnea is defined as the absence of inspiratory airflow for at least 10 seconds, which can be classified as obstructive or central [1]
An elevated matrix metalloproteinase-9 (MMP-9) secretion was reported to be induced by hypoxia conditions [11, 12], which triggered us to investigate whether and how serum MMP-9 in obstructive sleep apnea syndrome (OSAS) patients affects the risk of systematic hypertension and heart dysfunction
By analyzing the hypertension-free survival, we found that OSAS severity (Figure 3(b)), lowest sleeping SpO2 (Figure 3(c)), and serum MMP-9 (Figure 3(d)) were all risk factors for hypertension onset

Summary

Introduction

Apnea is defined as the absence of inspiratory airflow for at least 10 seconds, which can be classified as obstructive or central [1]. A recent study reported a statistical correlation between higher serum matrix metalloproteinase-9 (MMP-9) level and the progression of blood pressure in healthy individuals [6]. An elevated MMP-9 secretion was reported to be induced by hypoxia conditions [11, 12], which triggered us to investigate whether and how serum MMP-9 in OSAS patients affects the risk of systematic hypertension and heart dysfunction. By testing the serum level of MMP-9 in these patients, we can tell its statistical correlation with OSAS severity. We followed up the cases without cardiovascular dysfunction to explore the effect of MMP-9 on the occurrence of hypertension and/or left ventricular hypertrophy in OSAS patients. We performed cellular and molecular experiments to investigate the possible functional mechanisms of MMP-9 in promoting cardiovascular diseases of OSAS patients

Patients and Methods

Results

Discussion