**2. Pathogenesis and profile of various organ involvement in COVID-19**

COVID-19 disease affects all organs of the body, predominantly lung, manifesting in form of severe acute respiratory syndrome (SARS) [11–14]. Multiple organ dysfunction is reported in severe manifestation of COVID-19 infection and is considered as late manifestation, while loss of sense of smell and of taste; a neurological manifestation, is reported as an early sign [11]. Mechanisms of COVID-19 induced multi-organ dysfunction is multi factorial.

Angiotensin-converting enzyme-2 (ACE 2) receptors, inflammatory mediators, rouge antibodies (autoantibodies), and dysregulated host response play important role in pathogenesis of COVID-19 organ involvement [12]. COVID-19 can also regarded as

#### *COVID-19 and Multiorgan Dysfunction Syndrome DOI: http://dx.doi.org/10.5772/intechopen.99676*

autoimmune disorder in which auto-antibodies formation leads to organ dysfunction and severe disease and are called Rouge antibodies". They are auto- antibodies which is non-protective and may play part in targeted longer term organ demage [12].

SARS-CoV-2 virus enters human respiratory epithelial cells through attachment of its spike (S) protein to the human angiotensin converting enzyme-2(h-ACE2). Angiotensin-converting enzyme 2 (ACE2) is a key player in pathogenesis of lung involvement leading to SARS. ACE-2 also works as a receptor site and entry point of virus to host cells. Disruption of ACE/ACE2 balance and RAAS activation is responsible for COVID-19 progression which can lead to severe disease and result in multi organ dysfunction especially in patients having co-morbidities like diabetes mellitus, hypertension, and cardiovascular disease [13]. Massive cytokine release, immune depression, cytopathic effect of virus are other mechanisms by which severe COVID-19 disease develops which can result in multi-organ dysfunction [14].
