Neuroprotective Mechanisms of Melatonin in Hemorrhagic Stroke.

Hemorrhagic stroke which consists of subarachnoid hemorrhage and intracerebral hemorrhage is a dominant cause of death and disability worldwide. Although great efforts have been made, the physiological mechanisms of these diseases are not fully understood and effective pharmacological interventions are still lacking. Melatonin (N-acetyl-5-methoxytryptamine), a neurohormone produced by the pineal gland, is a broad-spectrum antioxidant and potent free radical scavenger.

B7-H4 expression is elevated in human U251 glioma stem-like cells and is inducible in monocytes cultured with U251 stem-like cell conditioned medium.

Previous studies indicated that B7-H4, the youngest B7 family, negatively regulates T cell-mediated immunity and is significantly overexpressed in many human tumors. Tumor stem cells are purported to play a role in tumor renewal and resistance to radiation and chemotherapy. However, the link between B7-H4 and tumor stem cells is unclear.