Neutrophil extracellular traps (NETs) play an important role in the formation of immunothrombosis. However, how vascular endothelial cells mediate the formation of NETs has not been fully understood. We stimulated neutrophils firmly attached on the endothelial cell surface intercellular adhesion molecule-1 (ICAM-1) with lipopolysaccharide (LPS) or phorbol-12-myristate-13-acetate (PMA) for 4 h, then labeled NETs-DNA with Sytox green dye and the formation of NETs was observed by fluorescent microscopy. The area and fluorescence intensity of NETs-DNA were analyzed to quantify the formation of NETs. The results showed that both PMA and LPS were able to induce firmly adhered neutrophils on ICAM-1 to produce NETs. NETs induced by PMA were independent of neither β2 integrin lymphocyte function-associated antigen-1 (LFA-1) nor macrophage antigen complex-1 (Mac-1). In contrast, LPS-stimulated NETs were mediated by Mac-1 integrin, but not by LFA-1. After inhibition of actin filaments or Talin-1, the formation of NETs irrespective of the stimulus was significantly reduced. This study reveals the mechanism of the direct interaction between neutrophils and endothelial cells to produce NETs under inflammatory conditions, providing a new theoretical basis for the treatment of related diseases and the development of new drugs.
ObjectiveTo explore the effectiveness of proximal femoral nail antirotation (PFNA) assisted by mesh locator in treatment of intertrochanteric fracture in the elderly.MethodsNinety-four elderly patients with intertrochanteric fractures admitted between August 2014 and July 2017 were selected as the study subjects. They were randomly divided into trial group (48 cases) and control group (46 cases). In trial group, PFNA was implanted assisted by mesh locator after closed reduction; while in control group, PFNA was implanted by conventional method. There was no significant difference between the two groups in terms of gender, age, cause of injury, time from injury to admission, fracture side and classification, and medical complications (P>0.05). The operation time, intraoperative blood loss, fluoroscopy times, hospital stay, incision length, and complications were recorded. Visual analogue scale (VAS) was used to evaluate the degree of pain at 3 days after operation, and Harris score was used to evaluate hip function before operation and at 3, 6, and 9 months after operation.ResultsCompared with control group, the operation time and incision length of trial group shortened, the blood loss and fluoroscopy times reduced, the pain after operation alleviated obviously; the differences between the two groups were significant (P<0.05). There was no significant difference in hospital stay between the two groups (P>0.05). The patients in both groups were followed up 9-12 months, with an average of 10.6 months. X-ray films showed that the fractures healed in both groups, and the healing time in control group was (11.2±3.2) weeks, while that in trial group was (11.6±2.9) weeks, showing no significant difference between the two groups (t=1.262, P=0.120). There was no significant difference in Harris score between the two groups before operation and at 3, 6, and 9 months after operation (P>0.05). There was 1 case of incision infection, 2 cases of coxa vara, and 1 case of pressure ulcer in trial group, and the incidence of complications was 8.3%. There was 1 case of coxa vara, 2 cases of pressure ulcer, and 1 case of internal fixation loss in control group, and the incidence of complications was 8.7%. There was no significant difference in the incidence of complications between the two groups (χ2=0.783, P=0.112).ConclusionIt is feasible to implant PFNA assisted by mesh locator in treatment of intertrochanteric fracture in the elderly. Compared with the traditional operation, it can shorten the operation time, shorten the incision, and relieve the pain after operation.
Extracellular traps released by neutrophils (neutrophil extracellular traps, NETs) are a double-edged sword, and understanding the mechanism of NET formation is of great significance for disease treatment. However, the short lifespan, the large individual differences, and the inability to perform gene editing render it difficult to decipher NET formation using neutrophils. It is necessary to find a model cell to replace neutrophils to study the mechanism of NET formation. In this study, we used different concentrations (0, 0.1, 1, and 10 μmol/L) of all-trans retinoic acid (ATRA) to differentiate HL-60 cells for different days (1, 3, 5, and 7 days). By detecting the cell viability and nuclear morphology of cells, we confirmed that HL-60 cells were differentiated to neutrophil-like cells (dHL-60) after treated with ATRA for at least 5 days. Using immunofluorescence staining to detect the formation of NETs, we demonstrated that dHL-60 cells differentiated for 5 days with 1 μmol/L ATRA could generate NETs comparable to those produced by neutrophils upon phorbol 12-myristate 13-acetate (PMA) stimulation, without histone H3 citrullination. Furthermore, the formation of NETs by dHL-60 cells were NADPH-dependent and PAD4-independent, consistent with neutrophils. Taken together, these observations suggest that dHL-60 cells differentiated with 1 μmol/L ATRA for 5 days can be used as a model cell for neutrophils to study the mechanism of NET formation.