Definition of Cytokine storm syndrome (CSS)
Cytokine storm syndrome (CSS) is characterized by secretion of large amounts of cytokines including IL-1α, IL-1β, IL-6, IL-18 and TNF-α, continuous activation of lymphocytes and macrophages causing immune dysregulation, and finally, overwhelming systemic inflammation and multi-organ failure (MOF) with high mortality [5].
The term CSS was first used after allogeneic stem cell transplant to describe the hypercytokinemia (increased blood cytokines) in graft. Many viral, bacterial and parasitic infections can cause CSS such as Mycobacterium tuberculosis and Epstein-Barr virus (EBV), which cause pathological immune activation characterized by elevated cytokines such as interferon-γ (IFN-γ) in patients with immune defects [6].
It has been found that SARS-CoV2 is related to the dysfunction or damage of liver tissue, and after the lung, it seems to be the second organ. Acute liver failure (ALF) in COVID-19 patients may result from the virus invasion, which directly infects liver cells. Some infections of the upper respiratory tract can influence the liver. The function of the liver can be considered as a marker of disease progression, as the high frequency of serious COVID-19 cases showed of liver injury than mild cases. Several studies on COVID-19 patients primarily have demonstrated various degrees of raised serum biochemistries of the liver, such as irregular aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin (TB) levels. In another study, the elevated level of AST was identified in ICU admitted patients (62%) more frequently than other hospitalized patients (25%). Therefore, the ALF was predominant in critically ill cases than mild cases. Elevated GGT, a diagnostic factor of cholangiocyte injury, and ALP levels were reported in 30/56 (54%) and 1/56 (1.8%), respectively among COVID-19 patients during hospitalization. The higher levels of ALF indicators, especially AST, are strongly attributed to the higher mortality risk [7, 8].