ABSTRACT
Objective To examine the expression profile of programmed death-ligand 1 (PD-L1) on lung endothelial or epithelial cells,and to determine the specific role of PD-L1 in mouse model of indirect acute lung injury (i-ALI).Methods Eighty male C57BL/6 mice were randomly divided into two parts (both n =40).The effects of different administration routes on the expression of PD-L1 were observed.The mice in each part were randomly divided into sham,i-ALI,i-ALI+small interfering RNA (siRNA) random sequence control,and i-ALI+PD-L1 siRNA which could specifically inhibit PD-L1 expression groups,with l0 mice in each group.i-ALI was reproduced in a mouse model of hemorrhagic shock in combination with a subsequent cecal ligation and puncture (CLP).In sham group,only bilateral femoral arteries were ligated without catheterization or bleeding,and only cecum was separated but perforation was not ligated.Intravenous or intratracheal delivery of PD-L1 siRNA was performed 2 hours following the resuscitation to suppress the expression of PD-L1 on lung endothelial or epithelial cells.The mice in i-ALI+siRNA random sequence control group were given siRNA random sequence without inhibition effect on PD-L1 expression,and those in sham group and i-ALI group were given 100 μL phosphate buffered saline (PBS).The mice were sacrificed at 24 hours after CLP,and samples of blood,lung tissue and bronchoalveolar lavage fluid (BALF) were harvested.Expressions of PD-L1 were determined with flow cytometry.Cytokines and chemokines in plasma,lung tissue and BALF were determined by enzyme linked immunosorbent assay (ELISA).The protein concentration in plasma and BALF and the activity of myeloperoxidase (MPO) in lung tissue were quantitatively measured.The pathological changes in lung tissue were observed under light microscope.Results ① Compared with sham group,PD-L1 expression on lung endothelial or epithelial cells were significantly elevated in i-ALI group [endothelial cells:(27.88 ± 1.53)％ vs.(19.64 ± 1.03)％,epithelial cells:(58.70 ± 8.21)％ vs.(29.23 ± 3.94)％,both P ＜ 0.05].② Mice received intravenous delivery of liposomal-encapsulated siRNA had significantly lower expression of PD-L1 on lung endothelial cells as compared with that of i-ALI group [(21.37 ± 0.76)％ vs.(27.88 ± 1.53)％,P ＜ 0.05].Intratracheal delivery of naked PD-L1 siRNA mainly inhibited the PD-L1 expression on epithelial cell as compared with that of i-ALI group [(31.23±4.71) ％ vs.(58.70±8.21) ％,P ＜ 0.05].The expression of PD-L1 in pulmonary microvascular endothelial cells or pulmonary epithelial cells of i-ALI mice was not affected by siRNA random sequence.③ PD-L1 silencing on pulmonary endothelial cells induced by intravenous delivery of PD-L1 siRNA led to a lower protein ratio of BALF/plasma [(4.48 ± 0.35) × 10-3 vs.(6.11 ± 0.56) × 10-3,P ＜ 0.05] and a decreased MPO activity in lung tissue (U · μg-1 · min-1:2.48 ± 0.47 vs.4.56 ± 0.52,P ＜ 0.05) as compared with that of i-ALI group.Moreover,inflammatory mediator levels such as interleukin-6 (IL-6),monocyte chemoattractant protein-1 (MCP-1),macrophage inflammatory protein-2 (MIP-2) and tumor necrosis factor-α (TNF-α) in lung tissue or plasma were significantly reduced following PD-L1 suppression on endothelial cells as compared with those of i-ALI group [IL-6 (ng/g):177.4±23.2 vs.287.9±57.3,MCP-1 (ng/g):839.6±91.7 vs.1 395.7±211.9,MIP-2 (ng/g):923.7± 107.3 vs.1 700.9±240.2 in lung tissue;IL-6 (ng/L):950.2±192.7 vs.1 828.2±243.6,TNF-α (ng/L):258.7±29.1 vs.443.0 ± 58.1,MCP-1 (ng/L):2 583.8±302.3 vs.4 328.1 ±416.4,MIP-2 (ng/L):1 512.9± 165.6 vs.2 005.9 ± 85.7 in plasma,all P ＜ 0.05],however,there was no significant change in the levels of inflammatory factors in BALF.It was shown in lung tissue histology that PD-L1 silencing on pulmonary endothelial cells induced by intravenous delivery of PD-L1 siRNA led to lessened pulmonary edema and reduced immune cells emigration.Intratracheal delivery of PD-L1 siRNA for PD-L1 suppression on epithelial cells had minimal effects on protein ratio of BALF/plasma,MPO activity,inflammatory mediator expressions in lung tissue,plasma,and BALF as well as lung tissue histology.Conclusion PD-L1 silencing on endothelial cells but not epithelial cells protected mice against hemorrhagic shock-sepsis induced i-ALI.
ABSTRACT
Objective To evaluate the prognostic value of human antibacterial peptide LL-37 in elderly patients with sepsis. Methods Elderly sepsis patients over 65-year-old satisfied the diagnostic criteria for sepsis and septic shock admitted to intensive care unit of East Hospital of Tongji University from January 2016 to December 2017 were enrolled (elderly sepsis group). Aged community-acquired pneumonia (CAP) patients hospitalized during the same period were enrolled as a control group for pneumonia, and the aged health check-ups served as a healthy control group during the same period. The peripheral blood LL-37 levels of all patients on the 1st, 3rd, 7th day of admission and the results on the day of physical examination in the healthy control group and on the day of admission in aged CAP group were recorded. C-reactive protein (CRP), arterial blood lactate (Lac), procalcitonin (PCT) were monitored, and acute physiology and chronic health evaluation Ⅱ (APACHEⅡ) and sequential organ failure assessment (SOFA) scores were calculated based on the worst values within 24 hours. The correlation between LL-37 and various indicators was analyzed by Spearman method. According to the 28-day clinical outcome, the elderly patients with sepsis were divided into survival group and non-survival group. The differences in all parameters between the two groups were compared. The statistically significant indicators were analyzed by receiver operating characteristic (ROC) curve, and the predictive value of each indicator for prognosis was evaluated. Results ① A total of 113 elderly patients with sepsis were enrolled in the final analysis, including 67 patients in sepsis group and 46 patients in septic shock group. Thirty-two patients were enrolled as healthy controls and 31 elderly patients with CAP as elderly pneumonia group. The PCT, CRP, Lac, APACHEⅡ and SOFA scores of the patients in the three groups were higher than those of the healthy control group, and they were gradually increased with the severity of infection. There was no significant difference in gender or age among the groups. Compared with the healthy control group, the other three groups had higher LL-37 level after admission, the LL-37 levels in the sepsis group and the septic shock group were decreased with the prolongation of the hospitalization time, and they were lower than the pneumonia group at 7 days after admission [LL-37 (μg/L): 1 403.9±501.9, 1 517.1±676.4 vs. 1 608.4±816.2, both P > 0.05]. It was shown by correlation analysis that the LL-37 level in peripheral blood of elderly patients with sepsis was significantly negatively correlated with APACHEⅡ score (r = -0.329, P = 0.007) and SOFA score (r = -0.344, P = 0.005), but no significant correlation with Lac was found (r = -0.128, P = 0.311). ② The 28-day survival analysis revealed that of the 113 elderly patients with sepsis, 54 (47.8%) survived at 28 days and 59 (52.2%) died. There was no significant difference in gender, age, PCT or CRP levels at 1 day after admission between the two groups. The 1-day Lac, APACHEⅡ and SOFA scores of the patients in the non-survival group were significantly higher than those in the survival group, they were gradually increased with the prolongation of the hospitalization time, and they were significantly higher than those in the survival group at 7 days after admission [Lac (mmol/L): 2.4 (1.4, 4.4) vs. 1.0 (0.8, 1.7), APACHEⅡ score: 21.77±5.85 vs. 13.74±4.99, SOFA score: 9.62±4.78 vs. 3.18±2.71, all P < 0.01]. With the prolongation of admission, there was no significant change in LL-37 level of peripheral blood in the survival group. The LL-37 level in the non-survival group showed a downward tendency, and it was significantly lower than that in the survival group at 7 days after admission (μg/L: 1 277.8±642.6 vs. 1 620.6±461.6, P < 0.05). It was shown by ROC curve analysis that the LL-37 in peripheral blood, Lac, APACHEⅡ score and SOFA score at 7-day of admission of elderly patients with sepsis had predictive value for prognosis, and LL-37 had the best predicted effect for 28-day death, the area under the ROC curve (AUC) of LL-37 was 0.670, 95% confidence interval (95%CI) = 0.513-0.757, when the optimal cut-off value was 1 283.0 μg/L, the sensitivity was 75.7%, and the specificity was 61.5%. Conclusions The expression of LL-37 increased in the early course of the disease in elderly patients with sepsis. However, as the disease progressed and worsened, the level of LL-37 had a decline tendency and was associated with death. The dynamic monitoring of LL-37 combined with APACHEⅡ and SOFA scores had clinical guidance value in predicting the prognosis of sepsis in the elderly.
ABSTRACT
Results showed that its action was satisfactory.Theclinical effects of all three kinds of disease were betterthan that of the control group,especially on the im-provement of deficiency of blood and Qi(P