Lipocalin-2-Mediated Insufficient Oligodendrocyte Progenitor Cell Remyelination for White Matter Injury After Subarachnoid Hemorrhage via SCL22A17 Receptor/Early Growth Response Protein 1 Signaling

Insufficient remyelination due to impaired oligodendrocyte precursor cell(OPC)differentiation and maturation is strongly associated with irreversible white matter injury(WMI)and neurological deficits.We analyzed whole transcriptome expression to elucidate the potential role and underlying mechanism of action of lipocalin-2(LCN2)in OPC differentiation and WMI and identified the receptor SCL22A17 and downstream transcription factor early growth response protein 1(EGR1)as the key signals contributing to LCN2-mediated insufficient OPC remyelination.In LCN-knockdown and OPC EGR1 conditional-knockout mice,we discovered enhanced OPC differentiation in developing and injured white matter(WM);consistent with this,the specific inactivation of LCN2/SCl22A17/EGR1 signaling promoted remyelination and neurological recovery in both atypical,acute WMI due to subarachnoid hemorrhage and typical,chronic WMI due to multiple sclerosis.This potentially represents a novel strategy to enhance differentiation and remyelination in patients with white matter injury.

Aggravated pulmonary injury after subarachnoid hemorrhage in PDGF-B^ret/ret mice

Background:Recent advances in surgical and neuroprotective strategies could effectively manage the pathophysiological progression of subarachnoid hemorrhage(SAH).However,pulmonary dysfunction frequently occurs in SAH patients with an increased risk of unsatisfactory outcomes.Based on the similar microvascular structures in the blood-air barrier and blood-brain barrier and possible brain-lung crosstalks,we believe that pericytes may be involved in both neurological and pulmonary dysfunction after SAH.Methods:In our experiments,platelet-derived growth factor B(PDGF-B)retention motif knockout(PDGF-Bret/ret)mice and adeno-associated virus PDGF-B were employed to show the involvement of pericyte deficiency and PDGF-B expression.Neurological score,SAH grade,hematoxylin-eosin staining,and PaO2/FiO2 ratio analysis were performed to evaluate the neurological deficits and pulmonary functions in endovascular perforation SAH models at 24 h after surgery,as well as western blotting and immunofluorescence staining for underlying molecular expressions.Results:We found that neonatal PDGF-Bret/ret mice exhibited pulmonary atelectasis 12 h after birth.Further investigation showed a decrease in PaO2/FiO2 and lung-specific surfactant proteins in adult PDGF-Bret/ret mice.These dysfunctions were much worse than those in wild-type mice at 24 h after SAH.PDGF-B overexpression alleviated pulmonary dysfunction after SAH.Conclusions:These results suggested pulmonary dysfunction after SAH and the pivotal role of PDGF-B signaling for the pathophysiological process and future therapeutic targets of pulmonary injury treatment after SAH.Further studies are needed for pathophysiological investigations and translational studies on pulmonary injuries after SAH.