Treating obstructive sleep apnea with continuous positive airway pressure benefits type 2 diabetes management

Up-regulation of selenoprotein P and HIP/PAP mRNAs in hepatocytes by intermittent hypoxia via down-regulation of miR-203

Sleep apnea syndrome is characterized by recurrent episodes of oxygen desaturation and reoxygenation (intermittent hypoxia [IH]) and is a risk factor for insulin resistance/type 2 diabetes. However, the mechanisms linking IH stress and insulin resistance remain elusive. We exposed human hepatocytes (JHH5, JHH7, and HepG2) to experimental IH or normoxia for 24 h, measured mRNA levels by real-time reverse transcription polymerase chain reaction (RT-PCR), and found that IH significantly increased the mRNA levels of selenoprotein P (SELENOP) — a hepatokine — and hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein (HIP/PAP) — one of REG (Regenerating gene) family. We next investigated promoter activities of both genes and discovered that they were not increased by IH. On the other hand, a target mRNA search of micro RNA (miRNA) revealed that both mRNAs have a potential target sequence for miR-203. The miR-203 level of IH-treated cells was significantly lower than that of normoxia-treated cells. Thus, we introduced miR-203 inhibitor and a non-specific control RNA (miR-203 inhibitor NC) into HepG2 cells and measured the mRNA levels of SELENOP and HIP/PAP. The IH-induced expression of SELENOP and HIP/PAP was abolished by the introduction of miR-203 inhibitor but not by miR-203 inhibitor NC. These results demonstrate that IH stress up-regulates the levels of SELENOP in human hepatocytes to accelerate insulin resistance and up-regulates the levels of HIP/PAP mRNAs to proliferate such hepatocytes, via the miR-203 mediated mechanism.

Diabetic kidney disease and obstructive sleep apnea: a new frontier?

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) has been shown to be an independent risk factor for the development and progression of diabetes mellitus. Interestingly, there is also a strong correlation between OSA and the development and progression of chronic kidney disease (CKD). As diabetes mellitus is the most common cause of CKD, in this review we summarize the current literature regarding this interconnecting relationship between OSA, CKD, and diabetes mellitus. The literature increasingly supports a bidirectional relationship between CKD and OSA among diabetes mellitus patients leading to an increased rate of progression of diabetic nephropathy.

RECENT FINDINGS

There is growing evidence that among patients with diabetes mellitus, OSA may be a strong risk factor for the development of diabetic nephropathy. The treatment of OSA in CKD patients may play a role in attenuating the rate of the progression of CKD.

SUMMARY

Clinicians should have a low threshold for evaluating diabetic patients with CKD for OSA. Further studies examining if treatment of OSA would improve the outcomes of CKD patients in general and diabetic CKD patients in particular are needed.

Obstructive Sleep Apnea in Pregnancy: Assessment of Current Screening Tools

OBJECTIVE

To estimate the predictive ability of current obstructive sleep apnea (OSA) screening tools and the individual questions in these tools at identifying pregnant women who have OSA.

METHODS

A total of 293 third-trimester patients were enrolled between 2010 and 2012, and 248 patients had sleep monitor results. Recruited participants completed a questionnaire consisting of six OSA screening tools and overnight portable sleep monitoring. Predictive ability of the screening tools for OSA compared with results of the diagnosis from overnight sleep monitoring was estimated using the area under receiver operating characteristic curves.

RESULTS

Two hundred eighteen (88%) of the patients were OSA-negative, and 30 patients (12%) were OSA-positive based on sleep monitoring results. Compared with OSA-negative patients, OSA-positive patients had greater body mass indices and neck circumferences as well as significantly higher rates of hypertension (chronic and gestational), pregestational diabetes mellitus, asthma, and preeclampsia. The overall predictive ability of the screening tools for OSA was modest (area under receiver operating characteristic curves 0.62-0.695). However, individual components of the questionnaire were strongly associated with OSA.

CONCLUSION

We found that none of the studied OSA screening tools accurately detected OSA in pregnant women in the third trimester. We have identified proposed elements of a new screening tool based on promising components from several tools that may more accurately detect patients with OSA.

LEVEL OF EVIDENCE

II.

Resveratrol attenuates intermittent hypoxia-induced macrophage migration to visceral white adipose tissue and insulin resistance in male mice

Chronic intermittent hypoxia during sleep (IH), as occurs in sleep apnea, promotes systemic insulin resistance. Resveratrol (Resv) has been reported to ameliorate high-fat diet-induced obesity, inflammation, and insulin resistance. To examine the effect of Resv on IH-induced metabolic dysfunction, male mice were subjected to IH or room air conditions for 8 weeks and treated with either Resv or vehicle (Veh). Fasting plasma levels of glucose, insulin, and leptin were obtained, homeostatic model assessment of insulin resistance index levels were calculated, and insulin sensitivity tests (phosphorylated AKT [also known as protein kinase B]/total AKT) were performed in 2 visceral white adipose tissue (VWAT) depots (epididymal [Epi] and mesenteric [Mes]) along with flow cytometry assessments for VWAT macrophages and phenotypes (M1 and M2). IH-Veh and IH-Resv mice showed initial reductions in food intake with later recovery, with resultant lower body weights after 8 weeks but with IH-Resv showing better increases in body weight vs IH-Veh. IH-Veh and IH-Resv mice exhibited lower fasting glucose levels, but only IH-Veh had increased homeostatic model assessment of insulin resistance index vs all 3 other groups. Leptin levels were preserved in IH-Veh but were significantly lower in IH-Resv. Reduced VWAT phosphorylated-AKT/AKT responses to insulin emerged in both Mes and Epi in IH-Veh but normalized in IH-Resv. Increases total macrophage counts and in M1 to M2 ratios occurred in IH-Veh Mes and Epi compared all other 3 groups. Thus, Resv ameliorates food intake and weight gain during IH exposures and markedly attenuates VWAT inflammation and insulin resistance, thereby providing a potentially useful adjunctive therapy for metabolic morbidity in the context of sleep apnea.