ITIH4 and brain ischemia: found that ISG15 positively correlated with the degree of neuronal injury in animal models of ALS with no obvious signs of inflammation, a model cerebral ischemia, a model of cortical shock-induced brain injury, and a mouse model of chronic neuronal injury caused by the viral protein HIV gp120, with low levels of ISG15 in unaffected areas and high levels of ISG15 in neuronal injury areas.