The role of inflammation in the association between gestational diabetes and obstructive sleep apnea: A pilot study

Background

Obstructive sleep apnea is associated with pregnancy complications including gestational diabetes. Mechanisms underlying the association between obstructive sleep apnea and gestational diabetes remain to be elucidated.

Methods

Twenty-three participants with gestational diabetes underwent home sleep apnea testing. Obstructive sleep apnea was defined as an apnea hypopnea index > 5. Fasting morning blood samples were measured using multianalyte profiling (xMAP) multiplexed bead array immunoassay for Interleukin 6, tumor necrosis factor-alpha, and Interleukin 8.

Results

Age, body mass index, and gestational age at enrollment were 31 + 4.4 years, 35.7 + 7.4 kg/m², and 28 ± 4 weeks, respectively. Participants were 52% Caucasian and 16% had obstructive sleep apnea. We observed positive correlations between apnea hypopnea index and Interleukin 6 (r = 0.62, p = 0.005), Interleukin 8 (r = 0.56, p = .56), and tumor necrosis factor-alpha (r = .58, p = .009). Women with obstructive sleep apnea had higher levels of Interleukin 6 (F = 5.01, p = .037) and Interleukin 8 (F = 6.33, p = .021) vs. women without obstructive sleep apnea.

Conclusion

These preliminary results indicate that in women with gestational diabetes, apnea hypopnea index is associated with an elevated inflammatory profile.

The Differential Effects of Alcohol and Nicotine-Specific Nitrosamine Ketone on White Matter Ultrastructure

Aims

The chronic consumption of alcohol is known to result in neurodegeneration and impairment of cognitive function. Pathological and neuroimaging studies have confirmed that brain atrophy in alcoholics is mainly due to widespread white matter (WM) loss with neuronal loss restricted to specific regions, such as the prefrontal cortex. Neuroimaging studies of cigarette smokers also suggest that chronic inhalation of tobacco smoke leads to brain atrophy, although the neurotoxic component is unknown. As a high proportion of chronic alcoholics also smoke cigarettes it has been hypothesized that at least some alcohol-related brain damage is due to tobacco smoke exposure.

Methods

39 Long Evans rats were subjected to 8 weeks exposure to alcohol and/or 5 weeks co-exposure to nicotine-specific nitrosamine ketone (NNK), a proxy for tobacco smoke. Their frontal WM was then assayed with transmission electron microscopy.

Results

NNK and ethanol co-exposure had a synergistic effect in decreasing myelinated fibre density. Furthermore, NNK treatment led to a greater reduction in myelin sheath thickness than ethanol whereas only the ethanol-treated animals showed a decrease in unmyelinated fibre density.

Conclusion

These data suggest that NNK causes WM degeneration, an effect that is exacerbated by alcohol, but unlike alcohol, it has little impact on the neuronal components of the brain.

The rise and fall of insulin signaling in Alzheimer's disease

The prevalence of both diabetes and Alzheimer's disease (AD) are reaching epidemic proportions worldwide. Alarmingly, diabetes is also a risk factor for Alzheimer's disease. The AD brain is characterised by the accumulation of peptides called Aβ as plaques in the neuropil and hyperphosphorylated tau protein in the form of neurofibrillary tangles within neurons. How diabetes confers risk is unknown but a simple linear relationship has been proposed whereby the hyperinsulinemia associated with type 2 diabetes leads to decreased insulin signaling in the brain, with downregulation of the PI3K/AKT signalling pathway and its inhibition of the major tau kinase, glycogen synthase kinase 3β. The earliest studies of post mortem AD brain tissue largely confirmed this cascade of events but subsequent studies have generally found either an upregulation of AKT activity, or that the relationship between insulin signaling and AD is independent of glycogen synthase kinase 3β altogether. Given the lack of success of beta-amyloid-reducing therapies in clinical trials, there is intense interest in finding alternative or adjunctive therapeutic targets for AD. Insulin signaling is a neuroprotective pathway and represents an attractive therapeutic option. However, this incredibly complex signaling pathway is not fully understood in the human brain and particularly in the context of AD. Here, we review the ups and downs of the research efforts aimed at understanding how diabetes modifies AD risk.

Metabolic derangements mediate cognitive impairment and Alzheimer's disease: role of peripheral insulin-resistance diseases

Herein, we review evidence that systemic insulin-resistance diseases linked to obesity, type 2 diabetes, and non-alcoholic steatohepatitis promote neurodegeneration. Insulin-resistance dysregulates lipid metabolism, which promotes ceramide accumulation with attendant inflammation and endoplasmic reticulum (ER) stress. Mechanistically, we propose that toxic ceramides generated in extra-CNS tissues, e.g. liver, get released into peripheral blood, and subsequently transit across the blood-brain barrier into the brain where they induce brain insulin-resistance, inflammation, and cell death (extrinsic pathway). These abnormalities establish or help propagate a cascade of neurodegeneration associated with increased ER stress and ceramide generation, which exacerbate brain insulin-resistance, cell death, myelin degeneration, and neuro-inflammation. The data suggest that a mal-signaling network mediated by toxic ceramides, ER stress, and insulin-resistance should be targeted to disrupt positive feedback loops that drive the AD neurodegeneration cascade.

Profiles of neuronal thread protein expression in Alzheimer's disease

Neuronal thread proteins (NTPs) comprise a family of molecules expressed in brain and primitive neuroectodermal tumor cell lines. In Alzheimer's disease (AD), increased CNS levels of the 21 kD NTP species are correlated with dementia. The present study characterizes the nature and distribution of NTP expression using recently generated brain-derived polyclonal and monoclonal antibodies (MoAbs) to recombinant AD7c-NTP protein. In AD, high levels of NTP immunoreactivity were detected in neuronal perikarya, neuropil fibers, and white matter fibers (axons). In addition, 4 of the 23 AD7c-NTP MoAbs labeled degenerating neurons (with or without neurofibrillary tangles), axonal spheroids, dystrophic neurites, or irregular, wavy threadlike neuropil fibers in AD. Increased neuronal AD7c-NTP immunoreactivity in AD colocalized with perikaryal accumulations of tau-1, phosphorylated neurofilament, and the ganglioside, A2B5. In addition, AD7c-NTP immunoreactivity was detected in early neuritic plaques along with beta-amyloid-containing fibrils, but not in mature plaques, nor was it colocalized in beta A4-immunoreactive fibrils. This study demonstrates the profiles of NTP overexpression in relation to paired helical filament-associated neurodegenerative lesions in AD.