Objective To observe the effects of keratinocyte growth factor-2 (KGF-2) on the expressions of chemokine FKN and tight junction protein claudin-5 in lung tissue of rats with acute lung injury (ALI). Methods Healthy male Sprague-Dawley (SD) rats were randomly divided into normal saline (NS) control group, ALI model group and KGF-2 pretreatment group, with 10 rats in each group. The rat ALI model was reproduced by injection of 0.01 mL/kg oleic acid into the tail vein, and the rats in NS control group were injected with the same amount of NS. The rats in KGF-2 pretreatment group were instilled with 5 mg/kg KGF-2 in the airway at 72 hours before the model reproduction, and the rats in the NS control group and the ALI model group were instilled with the same amount of NS. The abdominal aortic blood of rats was collected at 8 hours after model reproduction, and then the rats were sacrificed, bronchoalveolar in left lung was lavage, and the bronchoalveolar lavage fluid (BALF) was collected for determination of protein levels in plasma and BALF, and the lung permeability index (LPI) was calculated. The lung tissues were harvested, after hematoxylin-eosin (HE) staining, the histopathological changes were observed under light microscope, and the ALI pathology score (LIS) was calculated. The lung wet/dry weight (W/D) ratio was determined. Immunohistochemistry and Western Blot were used to qualitatively and quantitatively analyze the expressions of FKN and claudin-5 in the lung tissue. The correlation between two variables was analyzed by linear or curve fitting correlation analysis. Results In the ALI model group, the lung tissue was severely damaged, and obvious pathological changes were observed, including thickened alveolar space and inflammatory cell infiltration, and LIS score, lung W/D ratio and LPI were significantly higher than those of the NS control group (LIS: 3.56±0.28 vs. 0.62±0.36, lung W/D ratio: 6.37±0.29 vs. 4.39±0.33, LPI: 3.46±0.69 vs. 0.98±0.17, all P < 0.01). Compared with the NS control group, the positive expression of FKN in the lung tissue of the ALI model group was significantly increased, and the expression level was significantly increased (FKN/GAPDH: 0.97±0.18 vs. 0.62±0.04, P < 0.01); the positive expression of claudin-5 was significantly decreased, and the expression level was significantly decreased (claudin-5/GAPDH: 0.56±0.11 vs. 1.06±0.13, P < 0.01). There was a significant negative correlation between FKN and claudin-5 protein expression (r = -0.817, P = 0.025). After pretreatment with KGF-2, the degree of lung tissue damage was significantly reduced, and the pathological changes were significantly improved, and the LIS score, lung W/D ratio and LPI were significantly lower than those of the ALI model group (LIS: 2.41±0.17 vs. 3.56±0.28, lung W/D ratio: 5.45±0.55 vs. 6.37±0.29, LPI: 2.42±0.19 vs. 3.46±0.69, all P < 0.01). Compared with the ALI model group, the positive expression of FKN in the lung tissue of KGF-2 pretreatment group was significantly decreased, and the expression level was significantly decreased (FKN/GAPDH: 0.79±0.03 vs. 0.97±0.18, P < 0.01); the positive expression of claudin-5 was significantly increased, and the expression level was significantly increased (claudin-5/GAPDH: 0.80±0.05 vs. 0.56±0.11, P < 0.01). There was still a significant negative correlation between FKN and claudin-5 protein expression (r = -0.847, P = 0.012). Conclusion KGF-2 may restore the expression of tight junction protein claudin-5 by down-regulating the expression of chemokine FKN, thereby reducing the damage of blood barrier in ALI.

OBJECTIVE To systematically evaluate the efficacy and safety of midazolam and dexmedetomidine/propofol for the sedation of critically ill patients undergoing mechanical ventilation， and to provide evidence-based reference for clinical treatment. METHODS Retrieved from PubMed， Embase， Web of Science， Cochrane Library， Clinical trials. gov， China Journal Full Text Database， Chinese Science and Technology Journal Database， Wanfang database and China Biomedical Literature Database， the data on the efficacy and safety of midazolam and dexmetomidine/propofol for the sedation of critically ill patients undergoing mechanical ventilation were collected from the establishment of the database to March 31， 2023. After extracting data from clinical studies that met the inclusion criteria， the meta-analysis was conducted by using the RevMan 5.3 statistical software. RESULTS A total of 31 literature were included， with a total of 2 765 patients. Results of meta-analysis showed that the mechanical ventilation time [MD＝14.13， 95%CI （13.75， 14.52）， P＜0.000 01] and the length of hospitalization in the intensive care unit [MD＝0.92， 95%CI （0.54， 1.30）， P＜0.000 01] of patients in the midazolam group was longer than dexmedetomidine/ propofol group. The incidence of bradycardia in midazolam group was lower dexmedetomidine/propofol group [OR＝0.60， 95%CI （0.41， 0.90）， P＝0.01]， but there was no statistically significant difference in the incidence of hypotension between the two groups [OR＝0.69， 95%CI （0.47， 1.01）， P＝0.06]. The incidence of delirium [OR＝3.88， 95%CI （2.74， 5.49）， P＜0.000 01]， ventilator- associated pneumonia [OR＝2.32， 95%CI （1.19， 4.51）， P＝0.01]， and respiratory depression [OR＝5.70， 95%CI （3.09， 10.52）， P＜0.000 01] in midazolam group were higher than dexmedetomidine/propofol group. CONCLUSIONS Compared with dexmedetomidine/propofol， midazolam increases patients’ mechanical ventilation time and the length of hospitalization in the intensive care unit in terms of efficacy， and increases the risk of delirium and pulmonary complications in terms of safety， but has a smaller cardiovascular impact.