COVID-19: Major Metabolic and Immunological Relationships in Obesity

Abstract
Introduction: In the scenario of chronic non-communicable diseases, obesity stands out as a multifactorial disease that can cause several public health problems. Currently, about 30% of the world's population is overweight or obese. Estimates suggest that the prevalence of severe obesity in 2030 will be 11%, approximately twice the current prevalence. By 2025, Brazil will be in fifth place in the world ranking, with an estimated 18.0 million people. The appearance of the new coronavirus (SARS-CoV-2), which causes the disease COVID-19, has worsened the comorbidities of obesity. Objective: to explore, through a concise systematic review, the main metabolic and immunological relationships in obesity, especially in the presence of COVID-19. Methods: The present study followed a concise systematic review model (PRISMA). The search strategy was carried out in the databases PubMed, Embase, Ovid and Cochrane Library, Web Of Science, and Scopus. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results: A total of 76 studies were found that were submitted to the eligibility analysis, and, after that, 15 studies of high to medium quality and with risks of bias were selected that do not compromise the scientific basis of the studies, we found that obesity is an important predictor of worsening SARS-CoV-2 pathology. There are a complex interaction between multiple metabolic, immunological and inflammatory factors that result in meta-inflammation. It has been shown that obesity causes dysfunction in the immune system, increasing susceptibility to infections and death from sepsis, and increased oxidative stress in the body. SARS-CoV-2 amplifies the inflammatory response, enabling greater propensity to alveolar thrombotic microangiopathy and pulmonary thromboembolism. Meta-inflammation and insulin resistance with hyperinsulinemia is the main baseline changes in obesity. Conclusion: In the COVID-19 scenario, obesity is an important predictor of the worsening of SARS-CoV-2 pathology, mainly due to the worsening of metainflammation.