Stretching the stress boundary: Linking air pollution health effects to a neurohormonal stress response

Environmental/lifestyle factors in the pathogenesis and prevention of type 2 diabetes

BACKGROUND

Environmental and lifestyle changes, in addition to the ageing of populations, are generally believed to account for the rapid global increase in type 2 diabetes prevalence and incidence in recent decades.

DISCUSSION

In this review, we present a comprehensive overview of factors contributing to diabetes risk, including aspects of diet quality and quantity, little physical activity, increased monitor viewing time or sitting in general, exposure to noise or fine dust, short or disturbed sleep, smoking, stress and depression, and a low socioeconomic status. In general, these factors promote an increase in body mass index. Since loss of β-cell function is the ultimate cause of developing overt type 2 diabetes, environmental and lifestyle changes must have resulted in a higher risk of β-cell damage in those at genetic risk. Multiple mechanistic pathways may come into play.

CONCLUSIONS

Strategies of diabetes prevention should aim at promoting a 'diabetes-protective lifestyle' whilst simultaneously enhancing the resistance of the human organism to pro-diabetic environmental and lifestyle factors. More research on diabetes-protective mechanisms seems warranted.

Ambient levels of concentrated PM2.5 affects cell kinetics in adrenal glands: an experimental study in mice

We evaluated the effects of air pollution on the adrenal cortex using 30 female mice divided into two groups of fifteen animals each. One group was conditioned daily in a chamber with exposure to particulate matter (PM) 2.5 μm (GExp). Animals were exposed on daily basis in an ambient particles concentrator during the period of time enough to reach an accumulated dose of 600 μg/m³, which corresponds to a 24-h exposure of 25 μg/m³ that approximates to the annual mean of PM2.5 in São Paulo. The other group was allocated to another chamber with filtered air (GCrt). After euthanasia, the adrenals underwent histological processing and immunohistochemistry staining for Ki-67 and cleaved caspase-3. Histomorphometry of the adrenal glands in GExp showed increased thickness of the zona glomerulosa, while in GCrt; the adrenal glands from GExp had higher Ki-67 immunostaining scores in the zona reticularis than those from GCrt. The adrenal from GExp showed higher cleaved caspase-3 immunoreactivity in the zona fasciculata than the unexposed group (GCrt). The homeostasis index indicated higher cell proliferation in the zona glomerulosa and zona reticularis in GExp than in GCrt. Our data indicate that PM2.5 air pollution induces alterations on cell kinetics in mouse adrenal glands.

A Voxel-Based Morphometry Study Reveals Local Brain Structural Alterations Associated with Ambient Fine Particles in Older Women

Objective: Exposure to ambient fine particulate matter (PM_2.5: PM with aerodynamic diameters < 2.5 μm) has been linked with cognitive deficits in older adults. Using fine-grained voxel-wise analyses, we examined whether PM_2.5 exposure also affects brain structure.

Methods: Brain MRI data were obtained from 1365 women (aged 71–89) in the Women's Health Initiative Memory Study and local brain volumes were estimated using RAVENS (regional analysis of volumes in normalized space). Based on geocoded residential locations and air monitoring data from the U.S. Environmental Protection Agency, we employed a spatiotemporal model to estimate long-term (3-year average) exposure to ambient PM_2.5 preceding MRI scans. Voxel-wise linear regression models were fit separately to gray matter (GM) and white matter (WM) maps to analyze associations between brain structure and PM_2.5 exposure, with adjustment for potential confounders.

Results: Increased PM_2.5 exposure was associated with smaller volumes in both cortical GM and subcortical WM areas. For GM, associations were clustered in the bilateral superior, middle, and medial frontal gyri. For WM, the largest clusters were in the frontal lobe, with smaller clusters in the temporal, parietal, and occipital lobes. No statistically significant associations were observed between PM_2.5 exposure and hippocampal volumes.

Conclusions: Long-term PM_2.5 exposures may accelerate loss of both GM and WM in older women. While our previous work linked smaller WM volumes to PM_2.5, this is the first neuroimaging study reporting associations between air pollution exposure and smaller volumes of cortical GM. Our data support the hypothesized synaptic neurotoxicity of airborne particles.