ABSTRACT
Objective To explore whether serum amyloid A (SAA) can induce the formation of neutrophil extracellular traps(NETs)in neutrophils in vitro. Methods A stable method for inducing NETs formation in vitro was established, in-cluding isolation of peripheral blood neutrophils, cell culture, and NETs formation and observation. The neutrophils were iso-lated from peripheral blood of healthy volunteers. And cells were cultured in vitro and classified into three groups:negative control (NC) group, SAA group and lipopolysaccharide (LPS) group. Following the distinct stimulation in three groups, NETs formation was observed and its percentage was calculated. The concentration of hinstone (h) 3 in supernatant was detected by ELISA. Results The purification and vitality of isolated neutrophils were both more than 95%. The nuclei of neutrophils lost their shape and spread, NETs formation was found. More NETs formation was found in SAA group than that in NC group (P < 0.05). Moreover, the concentration of h3 in supernatant was significantly higher in SAA group than that in NC group (P<0.05). Conclusion SAA can induce the formation of NETs in vitro.
ABSTRACT
Objective To investigate the role of scavenger receptor class B type 1 (SR-B1) signaling pathway in serum amyloid A (SAA)-induced angiogenesis in rheumatoid arthritis (RA).Methods The expression and location of SR-B1 in RA and osteoarthritis (OA) synovial tissues were observed by immunohistochemistry.And SR-B1 expression in the resting human umbilical vein endothelial cells (HUVECs) was detected by immunoflourescence.Wound repair assessement and tube formation assessement were employed to evaluate the effect on cell migration and tube formation stimulated by SAA and/or anti-SR-B1 antibody.The t-test and one-way analysis of variance (ANOVA) were used for statistical analysis.Results ① SR-B1 was significantly highly expressed in RA tissue samples (A=6 788±819) when compared to the minimal expression in OA (A =31 849±6 977,t=3.567,P＜0.01).Positive staining of SR-B1 was observed in RA synovial vascular endothelial cells and perivascular areas.② Strong staining for SR-B1 was observed in all HUVECs tested.③ Significant wound healing induced by SAA (MI=2.50±0.17) was found compared with the untreated controls (MI=1.00±0.09,q=14.38,P＜0.01),and the effects were inhibited in the presence of anti-SR-B1 antibody (MI=1.16±0.14,q=13.02,P＜0.01).④ Compared to the untreated group (branch point number:6.6±0.8),there was an enhanced formation of branched and capillary-hke tube structure followed by SAA stimulation (branch point number:19.0±1.1,q=25.04,P＜0.01) after culturing for 72 h,whereas,tube formation decreased markedly upon pre-treated with anti-SR-B1 antibody (branch point number:7.6±1.3,vs SAA,q =23.32,P＜0.01).Conclusion Our present study suggests that serum amyloid A may induce angiogenesis via SR-B1 signaling pathway in RA.