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Lymphocytes from intermittent hypoxia-exposed rats increase the apoptotic signals in endothelial cells via oxidative and inflammatory injury in vitro

Abstract

Objective

Obstructive sleep apnea (OSA) has been implicated as a risk factor for atherosclerosis. Intermittent hypoxia (IH) induces oxidative and immuno-inflammatory alterations that could contribute to atherosclerosis. The aim of this study was to examine the effect of lymphocytes from intermittent hypoxia-exposed rats on the apoptotic signals in endothelial cells and the interventional role of tempol.

Method

Male Wistar rats were randomly distributed into three groups (n = 8 each): control group, IH group, and tempol group (exposed to IH and treated with tempol). Lymphocytes isolated from the rats were coincubated subsequently with endothelial cells under normoxia or IH condition. We analyzed endothelial apoptosis-related proteins (Bcl-2, Bax, and caspase-3) by Western blotting and measured the marks of oxidative stress (MDA, SOD, and CAT) and inflammation (TNF-α, IL-8, CRP, and ICAM-1) in cocultural supernatants by ELISA. We also determined endothelial p22phox, c-fos, and HIF-1α messenger RNA (mRNA) expressions using real time PCR.

Results

A significant decrease in the Bcl-2 level and the Bcl-2/Bax ratio and a significant increase in Bax and caspase-3 levels in endothelial cells were observed when coincubated normoxically with lymphocytes from IH-exposed rats compared to control (P < 0.01). Moreover, the oxidative stress, inflammation, and mRNA expressions of endothelial p22phox, c-fos, and HIF-1α were elevated significantly (P < 0.01). The alterations induced by lymphocytes were partially restored by tempol pretreatment while exacerbated by intermittent hypoxic coincubation.

Conclusions

Lymphocytes from intermittent hypoxia-exposed rats increased the apoptotic signals in endothelial cells via oxidative and inflammatory injury in vitro, which could be attenuated by tempol.

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Acknowledgments

This work was supported by the grants from the National Natural Science Foundation of China (No. 81170071, 81270144 and 81100060).

Conflict of interest

The authors declare that they have no conflict of interest.

Author information

Correspondence to Baoyuan Chen.

Additional information

Hengjuan Guo and Jie Cao contributed equally to this work.

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Guo, H., Cao, J., Li, J. et al. Lymphocytes from intermittent hypoxia-exposed rats increase the apoptotic signals in endothelial cells via oxidative and inflammatory injury in vitro. Sleep Breath 19, 969–976 (2015). https://doi.org/10.1007/s11325-015-1128-8

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Keywords

  • Obstructive sleep apnea
  • Intermittent hypoxia
  • Apoptotic signals
  • Oxidative stress
  • Inflammation