6.5  SARS-CoV-2-liver injury
The SARS-CoV-2 infection has shown to increase the levels of ALT, AST, and bilirubin levels, indicating injury to the hepatic tissue [9,95,101,102]. Apart from these liver serum enzymes indicating hepatic damage, the levels of albumin were significantly decreased, indicating the severity of the infection [101]. The elated levels of gamma-glutamyl transferase (GGT) were observed only in patients with severe cases. In contrast, thealkaline phosphatize (AKP) levels remained unchanged irrespective of the severity of the infection [37] (represented in Table 1).
SARS-CoV and SARS-CoV-2 share the similarity in making an entry into the host cell through the ACE2 receptor. In addition to the type 2 cells in the lungs, both the bile duct cells and hepatocytes also express ACE2, which might be the reason that liver injury occurs during SARS-CoV-2 infection [103]. The bile duct epithelial cells are involved in immune responses and the regeneration of the hepatocytes [104]. Besides possessing a high number of ACE2 on its surface, bile duct cells are more prone to the SARS-CoV-2 infection resulting in liver injury, which indicates that the hepatocytes are not directly involved in the hepatic injury [37]. The histopathological manifestations of SARS-CoV-2 infected patients revealed mild lobular and portal activity and restrained microvascular steatosis [105]. The degree of liver damage is directly proportional to the severity of the SARS-CoV-2 infection. Still, the reason for the liver injury remains elusive. A recent study reported that the use of anti-viral medication lopinavir might result in hepatic damage [102]. Therefore, whether the liver injury is due to the virus entry or due to the drugs used as anti-viral medication needs to be elucidated.