OBJECTIVE: To analyze the pathogens distribution in patients with ventilator-associated pneumonia (VAP), and their association with anti-β-glucan receptor-1 (Dectin-1)/spleen tyrosine kinase (Syk) signaling pathway, and to provide scientific basis for formulating more effective treatment strategies and preventive measures. METHODS: A prospective study was conducted. 160 patients with VAP admitted to the department of critical care medicine of Xingtai People's Hospital from January 2021 to March 2023 were enrolled. The respiratory secretions of patients were collected for Candida colonization analysis, and then the bacteria in the respiratory secretions were identified by automatic microbial identification instrument. The expression levels of Dectin-1 and Syk in peripheral blood mononuclear cells were detected by fluorescent immunopolymerase chain reaction. Clinical pulmonary infection score (CPIS) was performed based on imaging, clinical and microbiological criteria. The basic data, pathogen distribution, Dectin-1 and Syk expression levels and CPIS score of the two groups were compared. Spearman test was used to analyze the correlation between the expression levels of Dectin-1 and Syk and respiratory Candida colonization and CPIS score. RESULTS: 160 VAP patients, 97 were Candida colonized (colonized group) and 63 were not (non-colonized group). There were significantly differences in gender (males: 57.73% vs. 41.27%, P = 0.042) and age (years: 57.98±12.46 vs. 62.09±10.61, P = 0.029) between the colonized group and the non-colonized group, while there were no significantly differences in the data of duration of mechanical ventilation, underlying diseases and primary diseases. The distribution of pathogenic bacteria showed that the infection rate of Staphylococcus aureus in the colonized group was significantly higher than that in the non-colonized group (24.74% vs. 7.94%, P < 0.05), and there was no significantly difference in the infection rate of other G-positive and G-negative bacteria between the two groups. The CPIS score in the colonized group was significantly higher than that in the non-colonized group (8.73±0.43 vs. 7.31±0.39, P < 0.01), and the expression levels of Dectin-1 and Syk in peripheral blood mononuclear cells were significantly higher than those in the non-colonized group (Dectin-1/U6: 0.86±0.22 vs. 0.47±0.16, Syk/U6: 0.77±0.18 vs. 0.42±0.11, both P < 0.01). The expression levels of Dectin-1 and Syk in peripheral blood mononuclear cells of VAP patients were significantly positively correlated with the colonization of respiratory Candida (r values were 0.754 and 0.631, respectively, both P < 0.05), and were significantly positively correlated with CPIS score (r values were 0.594 and 0.618, respectively, both P < 0.05). CONCLUSION The proportion of Staphylococcus aureus in VAP patients with respiratory Candida colonization is higher, and Dectin-1/Syk signaling pathway is significantly positively correlated with respiratory Candida colonization and CPIS score.
Humans ; Syk Kinase ; Lectins, C-Type/metabolism* ; Signal Transduction ; Pneumonia, Ventilator-Associated/metabolism* ; Prospective Studies ; Male ; Female ; Middle Aged ; Candida ; Aged

OBJECTIVE: To investigate the interaction between α-amylase (α-AMS) and inflammatory response in patients with ventilator-associated pneumonia (VAP) and their predictive value for prognosis. METHODS: A prospective cohort study was conducted. Patients with mechanical ventilation who were treated in the intensive care unit (ICU) of the Second Hospital of Hebei Medical University from June 2020 to June 2023 were enrolled, and the patients were divided into VAP group and non-VAP group according to whether VAP occurred. VAP patients were stratified into mild [acute physiology and chronic health evaluation II (APACHE II) < 10 scores], moderate (APACHE II were 10-20 scores), and severe (APACHE II > 20 scores) groups based on the APACHE II. All patients were followed up for 28 days. In addition, healthy subjects who underwent health examination in our hospital at the same time were selected as the healthy control group. Baseline data including gender, age, mechanical ventilation mode, mechanical ventilation time, underlying diseases, drug use, and laboratory test indicators were collected. The serum levels of α-AMS, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), C-reactive protein (CRP) and other inflammatory factors were analyzed and compared. Pearson correlation analysis was performed to analyze the correlation between serum α-AMS and inflammatory factors. Logistic regression was used to analyze the influencing factors of poor prognosis in patients with VAP. The receiver operator characteristic curve (ROC curve) was plotted to evaluate the predictive value of α-AMS on the poor prognosis of patients with VAP. RESULTS: A total of 100 mechanically ventilated patients were enrolled, including 60 cases in the VAP group and 40 cases in the non-VAP group. Among the patients with VAP, there were 24 cases in the mild group, 20 cases in the moderate group, and 16 cases in the severe group. A total of 44 patients survived at 28 days, while 16 died. Additionally, 100 healthy individuals were included as the healthy control group. Serum levels of α-AMS, IL-6, TNF-α and CRP in the VAP group were significantly higher than those in the non-VAP group and the healthy control group, while the levels of α-AMS, IL-6, TNF-α and CRP in the non-VAP group were significantly higher than those in the healthy control group. There were statistically significant differences in serum α-AMS, IL-6, TNF-α, CRP levels and APACHE II scores among VAP patients with different disease severities, and the levels of the above indicators in the severe group were significantly higher than those in the moderate group and mild group, and the levels of the above indicators in the moderate VAP group were significantly higher than those in the mild group. Pearson correlation analysis showed that serum α-AMS was positively correlated with IL-6, TNF-α, CRP, and APACHE II scores (r values were 0.404, 0.392 and 0.493, 0.493, all P < 0.01). Univariate analysis showed that age, mechanical ventilation, diabetes mellitus, ventilation time, ventilation position, prophylactic use of antimicrobial drugs, and serum α-AMS, IL-6, TNF-α, CRP, and APACHE II scores were correlated with the prognosis of VAP patients (all P < 0.05). Multivariate Logistic regression analysis identified age [odds ratio (OR) = 1.340, 95% confidence interval (95%CI) was 1.119-1.605], tracheostomy (OR = 3.050, 95%CI was 1.016-9.157), diabetes mellitus (OR = 1.379, 95%CI was 1.102-1.724), and ventilation time ≥ 7 days (OR = 2.557, 95%CI was 1.163-5.623) and serum α-AMS (OR = 1.428, 95%CI was 1.098-1.856), IL-6 (OR = 1.543, 95%CI was 1.005-2.371), TNF-α (OR = 2.228, 95%CI was 1.107-4.485), CRP (OR = 1.252, 95%CI was 1.131-1.387), APACHE II scores (OR = 1.422, 95%CI was 1.033-1.957) were independent influencing factors for the 28-day prognosis of patients with VAP (all P < 0.05). ROC curve analysis demonstrated that serum α-AMS, IL-6, TNF-α and CRP exhibited significant predictive performance on the prognosis of patients with VAP. The best cut-off value for α-AMS had a sensitivity of 81.3%, specificity of 75.0%, and an area under the ROC curve (AUC) of 0.791, which was significantly higher than those of inflammatory markers IL-6, TNF-α, and CRP (P < 0.05). The combined parameter diagnostic performance was significantly better than those of individual parameters (P < 0.05), with the highest diagnostic performance when combined, corresponding to an AUC of 0.868 (95%CI was 0.798-0.938), sensitivity of 87.5%, and specificity of 79.5%. CONCLUSIONS VAP in mechanically ventilated patients can lead to an increase in the levels of peripheral blood α-AMS and inflammatory factors, and there is an interaction between α-AMS and inflammatory markers in severe VAP patients. These markers are closely related to the severity of the disease and prognosis and have significant implications for predicting patient outcomes.
Humans ; Pneumonia, Ventilator-Associated/diagnosis* ; Prognosis ; Prospective Studies ; Respiration, Artificial ; alpha-Amylases/blood* ; Interleukin-6/blood* ; Male ; Female ; C-Reactive Protein/metabolism* ; APACHE ; Inflammation ; Middle Aged ; Intensive Care Units ; Tumor Necrosis Factor-alpha/blood* ; Aged

OBJECTIVE: To study the changes in the expression of rat beta-defensin-2 (RBD-2) gene in the lung tissue with P. aeruginosa (PA) pneumonia following tracheal mechanical ventilation (MV), and to evaluate the pathogenesis of ventilator-associated pneumonia (VAP). METHODS: A total of 58 normal healthy Sprague-Dawley rats, weighing between 280 and 320 g, were randomly divided into the control group and the conventional MV group (CMV). A tracheal catheter was inserted via mouth in every rat under urethane anesthesia. PA (1 MIC, 0.2 ml) was instilled into the tracheal in the control group. Rats of CMV group received MV (V(T)=12 ml/kg) through tracheal tube for 24 hours, and then were challenged intra-tracheally with PA (1 MIC, 0.2 ml). Fluid loss was replenished through intravenous infusion. The arterial catheter was used for hemodynamics, parameters were monitored, and arterial blood gases were determined. Samples of lung were harvested at 0 hours, 15 hours, 3 hours, 6 hours, 12 hours, 1 day, 3 days and 5 days, respectively, after bacterial challenge. The mRNA of RBD-2 was detected by reverse transcription-polymerase chain reaction (RT-PCR), and the protein levels were analyzed by Western blotting. RESULTS: Expression of RBD-2 mRNA and protein was lower in CMV group compared with the control 3 hours before instillation of bacteria. RBD-2 mRNA increased 3 hours after bacteria instillation, reaching the peak at 12-24 hours. No significant difference in RBD-2 expression between the control group and the CMV group within 3 hours, but it was significantly higher at 3 hours, 6 hours, 12 hours, 1 day, 3 days and 5 days in the control group than in the CMV group. The number of inflammatory cells infiltrating the bronchial submucous layer was significantly higher in the control group than in the CMV group (P<0.05). There was milder interstitial pulmonary edema and less red blood cells in the alveoli in the control group than in the CMV group. The mortality rate of the CMV group was 60%, which was significantly higher than that of the control group (20%, P<0.05). The positive rates of blood culture and bronchoalveolar lavage fluid (BALF) bacterial culture were also higher in the CMV group (P<0.05). The survival rate in CMV group (40%) was lower than that of the control group (P<0.05). CONCLUSION: The lowering of BD-2 gene and protein expression in the CMV group 3 hours after bacteria challenge might be one of the contributory factors in causing VAP.
Disease Models, Animal ; Lung/metabolism ; Lung/pathology ; Pneumonia, Ventilator-Associated/*metabolism ; Pneumonia, Ventilator-Associated/pathology ; RNA, Messenger/metabolism ; Random Allocation ; Rats, Sprague-Dawley ; beta-Defensins/genetics ; beta-Defensins/*metabolism