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Objective:To investigate the effect of proprotein convertase subtilisin/kexin type 9 (PCSK9) on platelet activation in sepsis.Methods:① Clinical trial: a prospective study was conducted. Patients with sepsis and septic shock aged ≥ 18 years old who met the diagnostic criteria of Sepsis-3 admitted to the department of intensive care medicine of the Affiliated Hospital of Binzhou Medical College from January to October in 2021 were selected as subjects. Healthy subjects in the same period were taken as healthy control group. Platelet count (PLT) in the first routine blood test after admission was recorded. Venous blood was taken 1 day after diagnosis, and serum PCSK9 level was determined by enzyme-linked immunosorbent assay (ELISA). The differences of PCSK9 level and PLT between the two groups were compared, and subgroup analysis was conducted based on PLT for patients with sepsis. The correlation between PCSK9 level and PLT in septic patients was analyzed by Pearson correlation method. ② Animal experiment: 80 male C57BL/6 mice were randomly divided into control group, sepsis model group [lipopolysaccharide (LPS) group], PCSK9 inhibitor pretreatment group (PCSK9 inhibitor+LPS group) and PCSK9 inhibitor control group (PCSK9 inhibitor group), with 20 mice in each group. The mouse model of sepsis was reproduced by intraperitoneal injection of LPS 12 mg/kg, and the control group and PCSK9 inhibitor group were intraperitoneally injected with the same amount of sterile normal saline. PCSK9 inhibitor+LPS group and PCSK9 inhibitor group were pretreated with PCSK9 inhibitor 5 mg/kg intraperitoneal injection for 7 days before injection of LPS or normal saline, respectively, and the control group and LPS group were injected with an equal amount of sterile normal saline. The lung tissues were taken for pathological and immunohistochemical observation 24 hours after modeling. Blood was taken from the heart for determining PLT. Platelet activation was detected by flow cytometry. The expression level of platelet-activation marker CD40L was detected by Western blotting.Results:① Clinical trial: there were 57 cases in the sepsis group and 27 cases in the healthy control group. Serum PCSK9 level in the sepsis group was significantly higher than that in the healthy control group (μg/L: 232.25±72.21 vs. 191.72±54.92, P < 0.05), and PLT was significantly lower than that in the healthy control group [×10 9/L: 146.00 (75.50, 204.50) vs. 224.00 (194.00, 247.00), P < 0.01]. Subgroup analysis showed that the serum PCSK9 level in the thrombocytopenia patients ( n = 20) was significantly higher than that in the non-thrombocytopenia patients ( n = 37; μg/L: 264.04±60.40 vs. 215.06±72.95, P < 0.01). Correlation analysis showed a significant negative correlation between serum PCSK9 levels and PLT in septic patients ( r = -0.340, P = 0.010). ② Animal experiment: there were no significant pathological changes in lung tissue in the control group and PCSK9 inhibitor group under light microscope, and no significant differences in PLT, platelet activation and plasma CD40L protein expression was found between the two groups. In the LPS group, a large number of inflammatory cells were infiltrated in the pulmonary interstitium, the alveolar structure was damaged obviously, the alveolar septum was widened, the alveolar cavity was extensively bleeding, the capillary dilatation with bleeding and platelet aggregation were found, the PLT was significantly decreased, the platelet activation and the expression level of CD40L protein in plasma were significantly increased. The infiltration of inflammatory cells in lung tissue of mice in the PCSK9 inhibitor+LPS group was reduced to a certain extent, the thickening of alveolar septa was reduced, the platelet aggregation in lung tissue was decreased as compared with the LPS group, the PLT was significantly increased (×10 9/L: 515.83±46.60 vs. 324.83±46.31, P < 0.05), the platelet activation and the expression level of CD40L protein in plasma were significantly decreased [positive expression rate of platelet activation dependent granule surface facial mask protein CD62P: (12.15±1.39)% vs. (18.33±2.74)%, CD40L protein (CD40L/β-actin): 0.77±0.08 vs. 1.18±0.10, both P < 0.05]. Conclusion:PCSK9 level has a certain effect on promoting platelet activation in sepsis, and inhibition of PCSK9 level may have potential research value in improving adverse outcomes caused by sepsis thrombocytopenia.
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Objective@#To evaluate the effect of Notch-Hes1 signaling blockade by a γ-secretase inhibitor on the expression of γδT17 cells in a mouse model of psoriasis-like skin inflammation.@*Methods@#Forty-five healthy specific pathogen-free (SPF) male BALB/c mice were randomly divided into control group, model group and intervention group by simple random sampling. The model group and intervention group were both topically treated with imiquimod 5% cream (62.5 mg once a day) on the shaved back, the intervention group were then intraperitoneally injected with the γ-secretase inhibitor DAPT (10 mg/kg once a day) immediately after topical application of imiquimod, and the control group were topically treated with equivalent amount of vaseline once a day. After 6-day treatment, psoriasis area and severity index (PASI) was used to evaluate changes of skin lesions. On day 7, blood samples were obtained from all the mice through heart puncture after anesthetization, and spleen and skin tissues were acquired to prepare single cell suspension. Spleen index was compared among the 3 groups. Skin tissues on the mouse back were resected and subjected to hematoxylin-eosin staining to observe histopathological changes. Flow cytometry was performed to determine the percentage of γδT17 cells in the spleen and skin tissues, real-time reverse transcription (RT) -PCR to measure the mRNA expression of Hes1 in single cell suspension of the spleen, and enzyme-linked immunosorbent assay (ELISA) to determine the serum level of interleukin (IL) -17A. Statistical analysis was carried out by using one-way analysis of variance and repeated measures analysis of variance for comparison of indices among groups, and Pearson correlation analysis for evaluating the correlation between different indices.@*Results@#Twenty-four hours after the final treatment, the intervention group showed milder psoriasis-like skin inflammation, lower PASI score, and milder degree of epidermal thickening and dermal inflammatory cell infiltration compared with the model group. The model group showed significantly increased spleen index (12.534 ± 1.636) , proportions of γδT17 cells in the spleen (24.659% ± 4.603%) and skin tissues (22.127% ± 5.670%) , mRNA expression of Hes1 in the spleen (4.867 ± 0.543) , and serum level of IL-17A ([22.478 ± 2.776] ng/L) compared with the control group (all P < 0.01) . However, the above indices were significantly lower in the intervention group (9.449 ± 1.040, 14.966% ± 5.770%, 13.631% ± 5.946%, 2.541 ± 0.347, [18.639 ± 1.816] ng/L) than in the model group (all P < 0.01) . In the model group and intervention group, there were positive correlations between the proportions of γδT17 cells in the spleen and serum levels of IL-17A (r = 0.56, 0.53 respectively, both P < 0.05) , between the proportions of γδT17 cells in skin lesions and PASI scores (r = 0.56, 0.52 respectively, both P < 0.05) , as well as between the mRNA expression of Hes1 in the spleen and the proportions of γδT17 cells (r = 0.61, 0.58 respectively, both P < 0.05) or serum levels of IL-17A (r = 0.60, 0.54 respectively, both P < 0.05) .@*Conclusion@#Notch-Hes1 signaling blockade by γ-secretase inhibitor can markedly inhibit the expression of γδT17 cells, and effectively alleviate the severity of psoriasis-like skin inflammation in mouse models.
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Objective To investigate the effects of Trim34α on the activation of luciferase reporter gene containing NF-κB promoter induced by adaptor proteins TAB2. Methods The total RNA was isolated from HeLa cells. After amplification with RT-PCR, the target sequences were cloned into 5'-Flag-pcDNA3.1 (+) vector. The recombinant vector was confirmed by restriction enzyme digestion, colony PCR and sequencing. It was transfected into HEK293T cells to detected Trim34α expression by Western blot. Simultaneously, the effects of Trim34α on the NF-κB activation induced by TAB2 were determined by dual-luciferase reporter assay. Results Restriction enzyme digestion, colony PCR and sequencing confirmed the vector was constructed successfully, furthermore it expressed Trim34α protein in HEK293T cells. Moreover, trim34α could form high-molecular-weight oligomeric protein, and here we called it trimsome. Interestingly, dual-luciferase assay showed that Trim34α could effectively block TAB2-induced NF-κB activation. Conclusion Trim34α was involved in negative regulation of TAB2-induced NF-κB activation and could form high-molecular-weight oligomer.