Microglia-derived ADAM9 promote GHRH neurons pyroptosis by Mad2L2-JNK-caspase-1 pathway in subarachnoid hemorrhage.

The incidence of growth hormone deficiency (GHD) after subarachnoid hemorrhage (SAH) is significantly higher than that of other neuroendocrine disorders, but the mechanism is still elusive. We used mass spectrometry to identify differentially expressed proteins in cerebrospinal fluid samples from a well-characterized cohort of patients. A total of 683 proteins were identified, including 39 upregulated proteins in the GHD group. ADAM9 was most highly associated with GHD. In vivo, ADAM9 colocalized with M1 microglia markers, GH and cognitive ability of mice decreased significantly, and microglia secreted ADAM9 significantly. ADAM9 regulates pyroptosis of GHRH neurons by the Mad2L2-JNK-caspase-1 pathway. Sorafenib inhibits ADAM9 secretion by microglia and improves GH levels and the cognitive ability of mice. This study found that the crosstalk between GHRH neurons and neuroglial cells in the hypothalamic arcuate nucleus, i.e., microglia, is an essential factor in the formation of GHD in SAH. We propose that neutralization of ADAM9 production by microglia might be a potential therapy for GHD after SAH.