Systemic Th17/IL-17A response appears prior to hippocampal neurodegeneration in rats exposed to low doses of ozone

Ozone-induced neurotoxicity: In vitro and in vivo evidence

Together with cities in higher-income nations, it is anticipated that the real global ozone is rising in densely populated areas of Asia and Africa. This review aims to discuss the possible neurotoxic pollutants and ozone-induced neurotoxicity: in vitro and in vivo, along with possible biomarkers to assess ozone-related oxidative stress. As a methodical and scientific strategy for hazard identification and risk characterization of human chemical exposures, toxicological risk assessment is increasingly being implemented. While traditional methods are followed by in vitro toxicology, cell culture techniques are being investigated in modern toxicology. In both human and rodent models, aging makes the olfactory circuitry vulnerable to spreading immunological responses from the periphery to the brain because it lacks the blood-brain barrier. The ozone toxicity is elusive as it shows ventral and dorsal root injury cases even in the milder dose. Its potential toxicity should be disclosed to understand further the clear mechanism insights of how it acts in cellular aspects. Human epidemiological research has confirmed the conclusions that prenatal and postnatal exposure to high levels of air pollution are linked to behavioral alterations in offspring. O3 also enhances blood circulation. It has antibacterial action, which may have an impact on the gut microbiota. It also activates immunological, anti-inflammatory, proteasome, and growth factor signaling Prolonged O3 exposure causes oxidative damage to plasma proteins and lipids and damages the structural and functional integrity of the mitochondria. Finally, various studies need to be conducted to identify the potential biomarkers associated with ozone and the brain.

A multifunctional chitosan-based hydrogel with self-healing, antibacterial, and immunomodulatory effects as wound dressing

Bacterial infection often leads to inflammatory responses and delays wound healing. Chitosan (CS)-based composite hydrogels can hold desirable mechanical properties and maintain excellent antibacterial abilities, and thus may be promising as wound dressings. Although CS-based hydrogels have been widely studied on the antibacterial and wound-healing abilities, their immunomodulatory abilities were rarely evaluated. Herein, we developed a multifunctional CS/Poly[2-(methacryloyloxy)ethyl] trimethyl ammonium chloride (PMETAC) hydrogel. In vitro, this hydrogel exhibited self-healing ability and excellent biocompatibility, promoted macrophage polarization towards M2 phenotype, and showed desirable antibacterial activity. In vivo, this hydrogel accelerated the wound regeneration process by reducing bacterial burden, increasing collagen deposition, stimulating angiogenesis, promoting macrophage polarization to M2 direction, and shifting the balance of T helper type 17 (Th17) cells towards anti-inflammatory regulatory T (Treg) cells. This work revealed the potential immunomodulatory effect of CS-based wound dressings and thus may provide a novel target for developing efficient wound healing tools.

Ozone Pollution, Oxidative Stress, Regulatory T Cells and Antioxidants

Ozone pollution, is a serious health problem worldwide. Repeated exposure to low ozone doses causes a loss of regulation of the oxidation–reduction systems, and also induces a chronic state of oxidative stress. This fact is of special importance for the regulation of different systems including the immune system and the inflammatory response. In addition, the oxidation–reduction balance modulates the homeostasis of these and other complex systems such as metabolism, survival capacity, cell renewal, and brain repair, etc. Likewise, it has been widely demonstrated that in chronic degenerative diseases, an alteration in the oxide-reduction balance is present, and this alteration causes a chronic loss in the regulation of the immune response and the inflammatory process. This is because reactive oxygen species disrupt different signaling pathways. Such pathways are related to the role of regulatory T cells (Treg) in inflammation. This causes an increase in chronic deterioration in the degenerative disease over time. The objective of this review was to study the relationship between environmental ozone pollution, the chronic state of oxidative stress and its effect on Treg cells, which causes the loss of regulation in the inflammatory response as well as the role played by antioxidant systems in various pathologies.

Air Pollution and Alzheimer's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Ambient air pollution has been associated with Alzheimer's disease (AD) in the elderly. However, its effects on AD have not been meta-analyzed comprehensively.

OBJECTIVE

We conducted a systematic review and meta-analysis to assess the associations between air pollution and AD incidence.

METHODS

We searched PubMed and Web of Science for indexed publications up to March 2020. Odds risk (OR) and confidence intervals (CI) were estimated for particulate matter (PM)10 (PM10), PM2.5, ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO). The subgroup analysis was conducted based on the pollution levels.

RESULTS

Nine studies were included in the meta-analysis and review. The OR per 10μg/m3 increase of PM2.5 was 1.95 (95% CI: 0.88-4.30). The corresponding values per 10μg/m3 increment of other pollutants were 1.03 (95% CI: 0.68-1.57) for O3, 1.00 (95% CI: 0.89-1.13) for NO2, and 0.95 (95% CI: 0.91-0.99) for PM10 (only one study), respectively. Overall OR of the five air pollutants above with AD was 1.32 (95% CI: 1.09-1.61), suggesting a positive association between ambient air pollution and AD incidence. The sub-analysis indicated that the OR (2.20) in heavily polluted regions was notably higher than that in lightly polluted regions (1.06). Although AD risk rate data related to SO2 or CO exposure are still limited, the epidemiologic and toxicological evidence indicated that higher concentration of SO2 or CO exposure increased risks of dementia, implying that SO2 or CO might have a potential impact on AD.

CONCLUSION

Air pollution exposure may exacerbate AD development.

microRNA-592 blockade inhibits oxidative stress injury in Alzheimer's disease astrocytes via the KIAA0319-mediated Keap1/Nrf2/ARE signaling pathway

MicroRNA-592 (miR-592) has been reported to play a significant role in mediating neuronal activity, but its possible link with Alzheimer's disease (AD) remains unclear. We aimed to explore the mechanism of miR-592 in oxidative stress (OS) injury of astrocytes (ASTs) from AD rat models induced by D-galactose or Aβ_25-35 injection. Bioinformatics website and dual-luciferase reporter gene assay clarified the binding affinity between miR-592 and KIAA0319. KIAA0319 was identified as a target gene of miR-592. The mechanism of miR-592, KIAA0319 and the Keap1/Nrf2/ARE signaling pathway in AD was examined after transducing miR-592 mimic, miR-592 inhibitor and siRNA-KIAA0319 into ASTs to query cell viability, OS injury and reactive oxygen species (ROS). The rat models of AD Exhibited highly expressed miR-592 and poorly expressed KIAA0319. Furthermore, inhibition of miR-592 diminished C-Keap1 expression and enhanced N-Nrf2 and NQO1 expression, thus promoting cell viability and reducing OS injury of ASTs. Taken together, these findings suggested that the downregulation of miR-592 inhibited OS injury of ASTs in rat models of AD by up-regulating KIAA0319 through the activation of the Keap1/Nrf2/ARE signaling pathway.

Ozone Pollution: A Major Health Hazard Worldwide

Oxides of nitrogen (NO_x) and volatile organic compounds (VOCs) released into the atmosphere can react in the presence of solar irradiation, leading to ozone formation in the troposphere. Historically, before clean air regulations were implemented to control NO_x and VOCs, ozone concentrations were high enough to exert acute effects such as eye and nose irritation, respiratory disease emergencies, and lung function impairment. At or above current regulatory standards, day-to-day variations in ozone concentrations have been positively associated with asthma incidence and daily non-accidental mortality rate. Emerging evidence has shown that both short-term and long-term exposures to ozone, at concentrations below the current regulatory standards, were associated with increased mortality due to respiratory and cardiovascular diseases. The pathophysiology to support the epidemiologic associations between mortality and morbidity and ozone centers at the chemical and toxicological property of ozone as a strong oxidant, being able to induce oxidative damages to cells and the lining fluids of the airways, and immune-inflammatory responses within and beyond the lung. These new findings add substantially to the existing challenges in controlling ozone pollution. For example, in the United States in 2016, 90% of non-compliance to the national ambient air quality standards was due to ozone whereas only 10% was due to particulate matter and other regulated pollutants. Climate change, through creating atmospheric conditions favoring ozone formation, has been and will continue to increase ozone concentrations in many parts of world. Worldwide, ozone is responsible for several hundreds of thousands of premature deaths and tens of millions of asthma-related emergency room visits annually. To combat ozone pollution globally, more aggressive reductions in fossil fuel consumption are needed to cut NO_x and VOCs as well as greenhouse gas emissions. Meanwhile, preventive and therapeutic strategies are needed to alleviate the detrimental effects of ozone especially in more susceptible individuals. Interventional trials in humans are needed to evaluate the efficacy of antioxidants and ozone-scavenging compounds that have shown promising results in animal studies.

Neutralization of IL-17 rescues amyloid-β-induced neuroinflammation and memory impairment

BACKGROUND AND PURPOSE

Alzheimer's disease (AD) is a common neurodegenerative disease characterized by a neuroinflammatory state, and to date, there is no cure and its treatment represents a large unmet clinical need. The involvement of Th17 cells in the pathogenesis of AD-related neuroinflammation has been reported in several studies. However, the role of the cytokine, IL-17 has not been well addressed. Herein, we investigate the effects of IL-17 neutralizing antibody (IL-17Ab) injected by i.c.v. or intranasal (IN) routes on amyloid-β (Aβ)-induced neuroinflammation and memory impairment in mice.

EXPERIMENTAL APPROACH

Aβ_1-42 was injected into cerebral ventricles of adult CD1 mice. These mice received IL-17Ab via i.c.v. either at 1 h prior to Aβ_1-42 injection or IN 5 and 12 days after Aβ_1-42 injection. After 7 and 14 days of Aβ_1-42 administration, we evaluated olfactory, spatial and working memory and performed biochemical analyses on whole brain and specific brain areas.

KEY RESULTS

Pretreatment with IL-17Ab, given, i.c.v., markedly reduced Aβ_1-42 -induced neurodegeneration, improved memory function, and prevented the increase of pro-inflammatory mediators in a dose-dependent manner at 7 and 14 days. Similarly, the double IN administration of IL-17Ab after Aβ_1-42 injection reduced neurodegeneration, memory decline, and the levels of proinflammatory mediators and cytokines.

CONCLUSION AND IMPLICATIONS

These findings suggest that the IL-17Ab reduced neuroinflammation and behavioural symptoms induced by Aβ. The efficacy of IL-17Ab IN administration in reducing Aβ_1-42 neurodegeneration points to a possible future therapeutic approach in patients with AD.

LINKED ARTICLES

This article is part of a themed section on Therapeutics for Dementia and Alzheimer's Disease: New Directions for Precision Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.18/issuetoc.