Environmental perturbations: Obesity

Obesity is associated with severe disease and mortality in patients with coronavirus disease 2019 (COVID-19): a meta-analysis

Background

The coronavirus disease 2019 (COVID-19) pandemic has led to global research to predict those who are at greatest risk of developing severe disease and mortality. The aim of this meta-analysis was to determine the associations between obesity and the severity of and mortality due to COVID-19.

Methods

We searched the PubMed, EMBASE, Cochrane Library and Web of Science databases for studies evaluating the associations of obesity with COVID-19.

Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using random- or fixed-effects models. Meta-regression analyses were conducted to estimate regression coefficients.

Results

Forty-six studies involving 625,153 patients were included. Compared with nonobese patients, obese patients had a significantly increased risk of infection.

(OR 2.73, 95% CI 1.53–4.87; I² = 96.8%), hospitalization (OR 1.72, 95% CI 1.55–1.92; I² = 47.4%), clinically severe disease (OR 3.81, 95% CI 1.97–7.35; I² = 57.4%), mechanical ventilation (OR 1.66, 95% CI 1.42–1.94; I² = 41.3%), intensive care unit (ICU) admission (OR 2.25, 95% CI 1.55–3.27; I² = 71.5%), and mortality (OR 1.61, 95% CI 1.29–2.01; I² = 83.1%).

Conclusion

Patients with obesity may have a greater risk of infection, hospitalization, clinically severe disease, mechanical ventilation, ICU admission, and mortality due to COVID-19. Therefore, it is important to increase awareness of these associations with obesity in COVID-19 patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-11546-6.

del V, Di Sciullo MP, Ramirez DC, Gomez Mejiba SE. Therapeutic targets to reduce the contribution of pulmonary neutrophilic inflammation towards obesity-associated co-morbidities: a mini-review

Epidemiology and experimental models have shown a close link between adipose tissue inflammation, systemic inflammation and pulmonary neutrophilic inflammation, which predispose obese patients to pulmonary diseases, obesity-associated co-morbidities and cancer. Increased content and activation of neutrophils in the lung microvasculature, resulting from peripheral activation of neutrophils, and increased adhesion of neutrophils to the lung microvasculature are important factors explaining the increased susceptibility of obese patients towards respiratory diseases and loss of insulin sensitivity. Mechanism-based therapies to break this link are urgently needed to reduce pulmonary damage in obesity, due to the growing prevalence of obesity world-wide. Current research suggests that these approaches should be focused on, one or more of the following: reduction of macrophage activation at the adipose tissue, healthy growing of adipose tissue by induction of Nrf-2, inhibition of NF-κB activation, reduction of circulating neutrophil activation, blocking adhesins/selectins, inhibition of neutrophil activation by targeting NADPH oxidase-2 activation, inhibition of myeloperoxidase activity and scavenging of hypochlorous acid. These strategies are expected to reduce adipose tissue inflammation, peripheral inflammation, pulmonary neutrophilic inflammation and obesity-associated co-morbidities.

Oxidative Stress in the Lung - The Essential Paradox

As eukaryotic life evolved, so too did the need for a source of energy that meets the requirements of complex organisms. Oxygen provides this vast potential energy source, but the same chemical reactivity which provides this potential also can have detrimental effects. The lung evolved as an organ that can efficiently promote gas exchange for the entire organism but as such, the lung is highly susceptible to its external environment. Oxygen can be transformed through both enzymatic and non-enzymatic processes into reactive oxygen species (ROS) and reactive nitrogen species (RNS), which can lead to protein, lipid, and DNA damage. Under normal conditions ROS/RNS concentrations are minimized through the activity of antioxidants located both intracellularly and in the epithelial lining fluid of the lung. Oxidative stress in the lung results when the antioxidant capacity is overwhelmed or depleted through external exposures, such as altered oxygen tension or air pollution, or internally. Internal sources of oxidative stress include systemic disease and the activation of resident cells and inflammatory cells recruited in response to an exposure or systemic response. Pulmonary responses to oxidative stress include activation of oxidases, lipid peroxidation, increases in nitric oxide, and autophagy. These internal and external exposures with the subsequent pulmonary responses contribute to development of diseases directly linked to oxidative stress. These include asthma, COPD, and lung cancers. While the vulnerability of the lung to oxidative stress is acknowledged, few effective preventative strategies or therapeutics are currently available.

Obesity as a risk factor for malignant melanoma and non-melanoma skin cancer

The dramatic increases in incidence of both obesity and many cancers including skin cancer emphasize the need to better understand the pathophysiology of both conditions and their connections. Melanoma is considered the fastest growing cancer and rates of non-melanoma skin cancer have also increased over the last decade. The molecular mechanisms underlying the association between obesity and skin cancer are not clearly understood but emerging evidence points to changes in the tumor microenvironment including aberrant cell signaling and genomic instability in the chronic inflammatory state many obese individuals experience. This article reviews the literature linking obesity to melanoma and non-melanoma skin cancer.