Preconditioned protective microglia by oxygen-glucose deprivation promote functional recovery in ischemic rats

Cryptotanshinone reduces neurotoxicity induced by cerebral ischemia-reperfusion injury involving modulation of microglial polarization

BACKGROUND

The diterpenoid cryptotanshinone (CTS) has wide biological functions, including inhibition of tumor growth, inflammation and apoptosis. The present study aimed to explore the possible effect of CTS on cerebral ischemia/reperfusion (I/R) injury and the underlying mechanisms.

METHODS

Male C57BL/6J mice underwent transient middle cerebral artery occlusion (tMCAO) and murine microglia BV2 cells were challenged by Oxygen/glucose deprivation, to mimic I/R and ischemic/hypoxic and reperfusion (H/R) injury, respectively. CTS was administered 0.5 h (10 mg/kg) after the onset of MCAO or 2 h (20μM) post OGD. Infarct volume and neurological deficit were measured. Immunofluorescence, qPCR, and western blot, were performed to detect the expression of cytokines, apoptotic marker, and M1/M2 phenotype-specific genes. Flow cytometry was applied for M1/M2 subpopulation or Annexin V/PI apoptosis assessment.

RESULTS

CTS significantly reduced cerebral infarct volume, neurologic deficit scores, pro-inflammatory cytokine production (IL-6, TNF-α, and IL-1β), apoptotic protein expression (cleaved caspase-3) of mice after tMCAO challenge. Furthermore, CTS attenuated CD16+ M1-type and elevated CD206+ M2-type microglia in vivo or in vitro.

CONCLUSIONS

We propose that the neuroprotective effect of CTS in the I/R or H/R context are explained modulation of microglial polarization, suggesting therapeutic potential for cerebral ischemic stroke.