Human albumin attenuates Mincle-associated early neuroinflammatory injury in subarachnoid hemorrhage rats / 中华神经科杂志

ABSTRACT

Objective To investigate the protective role of human serum albumin in treatment of monocyte-inducible C-type lectin (Mincle)-associated neuroinflammation in subarachnoid hemorrhage (SAH) rats and its underlying mechanisms.Methods Vascular perforation model was used to induce SAH.Ninety-two male SD rats were randomly assigned to sham (n =23),vehicle (n =23),low-dose albumin (0.63 g/kg,n =23) and high-dose albumin (1.25 g/kg,n =23) groups.Saline and albumin were intravenously injected into rats two hours after surgery.Modified Garcia scale was employed to assess neurological functions.Iba-1 and myeloperoxidase (MPO) staining was used to examine the activation of microglial cells and infiltration of neutrophils.Real-time PCR was applied to determine the changes of IL-1β,inducible nitric oxide synthase,CD11b,monocyte chemoattractant protein-1,cytokine-induced neutrophil chemoattractant-1 and CXC motif chemokine ligand-2 mRNA levels.Co-immunoprecipitation was conducted to assess the binding ability of albumin with Mincle.Immunoblotting was carried out to evaluate protein levels of Minlce,Syk and p-Syk.SAH severity measurement was performed before conductions of all the experiments.Results SAH severity scores were 11.4 ± 1.6,12.8 ±2.5 and 11.2 ±3.2 in the vehicle,low-dose albumin and high-dose albumin groups,respectively,without statistically significant difference among groups (F =0.694,P =0.516).Neurological score was 7.5 ± 2.9 in the vehicle group,while the low-dose albumin (14.6 ± 2.2) and high-dose albumin groups (13.6 ± 2.7) exhibited better neurological perfomance (P ＜ 0.01).Immunostaining showed that albumin significantly inhibited the activation of microglia,and reduced the percentage of MPO positive cells from 20.7％ ± 1.9％ in the vehicle group to 12.1％ ±2.1％ in the low-dose albumin group and 9.8％ ±0.9％ in the high-dose albunin group (F =32.216,P =0.001).mRNA levels of pro-inflammatory cytokines and chemotactic factors were also suppressed by albumin (P ＜ 0.05).The results of co-immunoprecipitation displayed that albumin could directly bind Mincle and disrupt the association between Mincle and SAP130.Immunoblotting demonstrated that albumin depressed the protein levels of Mincle,Syk and p-Syk.Conclusion Human serum albumin can inhibit Mincle/Syk-induced neuroinflammation via directly binding Mincle receptor in SAH rats.