Immune Response to SARS-CoV-2 Infection in Obesity and T2D: Literature Review

Abstract

In December 2019, a novel coronavirus known as SARS-CoV-2 was first detected in Wuhan, China, causing outbreaks of the coronavirus disease COVID-19 that has now spread globally. For this reason, The World Health Organization (WHO) declared COVID-19 a public health emergency in March 2020. People living with pre-existing conditions such as obesity, cardiovascular diseases, type 2 diabetes (T2D), and chronic kidney and lung diseases, are prone to develop severe forms of disease with fatal outcomes. Metabolic diseases such as obesity and T2D alter the balance of innate and adaptive responses. Both diseases share common features characterized by augmented adiposity associated with a chronic systemic low-grade inflammation, senescence, immunoglobulin glycation, and abnormalities in the number and function of adaptive immune cells. In obese and T2D patients infected by SARS-CoV-2, where immune cells are already hampered, this response appears to be stronger. In this review, we describe the abnormalities of the immune system, and summarize clinical findings of COVID-19 patients with pre-existing conditions such as obesity and T2D as this group is at greater risk of suffering severe and fatal clinical outcomes.

Does abdominal obesity influence immunological response to SARS-CoV-2 infection?

“…The risk for cardiovascular heart disease (CVD) is higher in people with ‘central’ or ‘visceral-abdominal’ obesity [ 8 ]; CVD, especially heart failure, is a significant risk factor for worse outcomes in COVID-19 [ 9 ]. The innate immune response is also altered in diseases, such as obesity and type 2 diabetes mellitus (T2DM), thus making people more susceptible to SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection [ 10 ]. However, a higher BMI is also frequently associated with a worse prognosis and higher mortality in COVID-19 patients [ 11 , 12 ].…”

Immunopathology and Immunosenescence, the Immunological Key Words of Severe COVID-19. Is There a Role for Stem Cell Transplantation?

“…Pattern recognition receptors (PRRs) expressed on innate immune cells, such as DCs and macrophages, recognize and bind surface viral epitopes, leading to anti-pathogen responses. The activation of these cells by the virus leads secretion of several inflammatory cytokines and chemokines, which activate and recruit other immune cells generating a positive feedback loop of inflammation ( Pérez-Galarza et al, 2021 ). Aging alters also these actors involved in innate immunity in terms of both number/percentage and functionality, with different quantitative and qualitative consequences for DCs, monocytes, macrophages, neutrophils and myeloid derived suppressor cells (MDSCs) ( Agrawal et al, 2017 ; Ventura et al, 2017 ; Oh et al, 2019 ; Feng et al, 2021 ).…”

Impact of Host Immune Status on Discordant Anti-SARS-CoV-2 Circulating B Cell Frequencies and Antibody Levels

“…It leads to the emergence of oligoclonal B cell populations with high serum oligoclonality, and to the presence of autoAb, particularly against coagulation and vessel targets [14,15]. These comorbidities have in common chronic systemic low-grade inflammation, with an abnormal production of pro-inflammatory cytokines and the impairment of T cell mediated immune response involved in host defense [16][17][18][19]. These immune defects affect several critical pathways that support the cooperation between T cells and B cells, such as the CD40/CD40 ligand pathway, which are probably even more deregulated by the inflammation caused by the SARS-CoV-2 infection.…”