Effects of varying degrees of intermittent hypoxia on proinflammatory cytokines and adipokines in rats and 3T3-L1 adipocytes.
OBJECTIVE
Intermittent hypoxia (IH), resulted from recurring episodes of upper airway obstruction, is the hallmark feature and the most important pathophysiologic pathway of obstructive sleep apnea (OSA). IH is believed to be the most important factor causing systemic inflammation. Studies suggest that insulin resistance (IR) is positively associated with OSA. In this study, we hypothesized that the recurrence of IH might result in cellular and systemic inflammation, which was manifested through the levels of proinflammatory cytokines and adipokines after IH exposure, and because IR is linked with inflammation tightly, this inflammatory situation may implicate an IR status.


METHODS
We developed an IH 3T3-L1 adipocyte and rat model respectively, recapitulating the nocturnal oxygen profile in OSA. In IH cells, nuclear factor kappa B (NF-κB) DNA binding reactions, hypoxia-inducible factor-1α (HIF-1α), glucose transporter-1 (Glut-1), necrosis factor alpha (TNF-α), interleukin (IL) -6, leptin, adiponectin mRNA transcriptional activities and protein expressions were measured. In IH rats, blood glucose, insulin, TNF-α, IL-6, leptin and adiponectin levels were analyzed.


RESULTS
The insulin and blood glucose levels in rats and NF-κB DNA binding activities in cells had significantly statistical results described as severe IH>moderate IH>mild IH>sustained hypoxia>control. The mRNA and protein levels of HIF-1α and Glut-1 in severe IH group were the highest. In cellular and animal models, both the mRNA and protein levels of TNF-α, IL-6 and leptin were the highest in severe IH group, when the lowest in severe IH group for adiponectin.


CONCLUSIONS
Oxidative stress and the release of pro-inflammatory cytokines/adipokines, which are the systemic inflammatory markers, are associated with IH closely and are proportional to the severity of IH. Because IR and glucose intolerance are linked with inflammation tightly, our results may implicate the clinical relationships between OSA and IR.
Department of Endocrinology, Tianjin Medical University General Hospital, Tianjin, China.
Qing
Q
He
Respiratory Department of Tianjin Medical University General Hospital, Tianjin, China.
Qing-chan
QC
Yang
Department of Endocrinology, Tianjin Medical University General Hospital, Tianjin, China.
Qin
Q
Zhou
Department of Endocrinology, Tianjin Medical University General Hospital, Tianjin, China.
Hui
H
Zhu
Immunology Department, Tianjin Medical University, Tianjin, China.
Wen-yan
WY
Niu
Respiratory Department of Tianjin Medical University General Hospital, Tianjin, China.
Jing
J
Feng
Respiratory Department of Tianjin Medical University General Hospital, Tianjin, China.
Yan
Y
Wang
Respiratory Department of Tianjin Medical University General Hospital, Tianjin, China.
Jie
J
Cao
Respiratory Department of Tianjin Medical University General Hospital, Tianjin, China.
Bao-yuan
BY
Chen
D017667:Adipocytes / Q000378:metabolism*; D054392:Adipokines / Q000097:blood / Q000378:metabolism*; D052242:Adiponectin / Q000097:blood / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D051272:Glucose Transporter Type 1 / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D007249:Inflammation / Q000378:metabolism*; D007328:Insulin / Q000097:blood / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology; D015850:Interleukin-6 / Q000097:blood / Q000378:metabolism; D020738:Leptin / Q000097:blood / Q000378:metabolism; D023421:Models, Animal; D016328:NF-kappa B / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D020181:Sleep Apnea, Obstructive / Q000097:blood / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000097:blood / Q000378:metabolism
D054392:Adipokines; D052242:Adiponectin; D001786:Blood Glucose; D016207:Cytokines; D051272:Glucose Transporter Type 1; C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007328:Insulin; D015850:Interleukin-6; D020738:Leptin; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D010100:Oxygen