Inflammation, Immunity and Immunogenetics in COVID-19: A Narrative Review

Abstract

The novel Coronavirus Disease 2019 (COVID-19), that began in Wuhan Province, China was labelled as an International Public Health Emergency on January 30, 2020 and later was declared a pandemic by the World Health Organisation (WHO) on March 11, 2020. The causative agent, SARS-CoV-2 was the third coronavirus responsible for causing major disease outbreaks in human population after Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) caused by SARS-CoV and MERS-CoV respectively. The patients of COVID-19 present with a clinical feature resembling mild form of viral pneumonia which in certain cases progress to a severe form characterised by adult respiratory distress syndrome (ARDS) and/or multiorgan failure leading to death. The transition from mild to severe form of COVID-19 is affected by a lot of factors like age, co-morbidities etc. In the absence of an absolute cure, it is essential to explore the molecular pathogenesis of the disease to identify people at risk of developing severity so that alternative treatment modalities may be planned. The aim of this review is to provide an update on the general characteristics of SARS-CoV-2 and highlight the inflammatory changes and immune dysregulation that may help in identification of molecular predictors of disease severity.

Obesity and COVID-19: A Fatal Alliance

“…These pro-inflammatory cytokines regulate the proliferation and apoptosis of adipocytes through various mechanisms. Elevated levels of inflammatory mediators are responsible for long-term effects on glucose homeostasis, food intake regulation and inflammatory responses [61][62][63][64][65].…”

Pneumolysis and “Silent Hypoxemia” in COVID-19

“…Likewise, comorbidity in any disease implies worse outcomes. The inflammatory changes and immune dysregulation could give rise to irreversible damage [20]. Fast contagion of susceptible and immunosuppressed individuals could explain the epidemiological curve peak and subsequent fall, interpreted as nature's cleansing.…”

“…Antibiotic overuse with microbiome alterations could also be associated with a deficient immune system [ 19 ]. Chronic inflammation processes determine the permanent production of cytokines, interleukins, and other inflammatory molecules [ 20 ]. Likewise, "healthy" subjects suffering from asymptomatic underlying inflammation could have an over-reactive capacity to produce an abundance of inflammatory markers that add to the inflammation triggered by the virus.…”

Association of Comorbidities with Coronavirus Disease 2019: A Review

“…These cytokines and chemokines such as interleukin-6 (IL-6), tumor necrosis factor (TNF), CXC chemokine ligand 10 (CXCL10), and CC chemokine ligand 2 (CCL2) act as some of the major drivers of SARS-CoV-2 associated hyperinflammation and, in due course, lead to multiorgan failure. 40 For a long time, diabetes was considered as one of the leading causes of morbidity and mortality throughout the world. Elderly people with T2DM are often the most vulnerable group toward infections such as influenza and pneumonia.…”