Intranasal lipopolysaccharide administration to Sprague-Dawley rats as a biomodel of acute respiratory distress syndrome

High fatality rate and the lack of pathophysiological therapy are typical for acute respiratory distress syndrome (ARDS). Intratracheal lipopolysaccharide (LPS) administration is used to model ARDS in animals. The method has the limitation of requiring the use of equipment to perform intubation and control the animal’s state. The study aimed to assess the possibility of using intranasal LPS administration instead of intratracheal and determine the LPS optimal dose. A total of 150 mL of the E. coli O111:B4 LPS (7.5 mg/kg or 15 mg/kg) or 0.9% NaCl was administered to 21 Sprague-Dawley rats. After 48 h blood was collected from the tail vein to determine the white blood cell count and TNFa concentration. The lungs were retrieved to assess dry weight (wet/dry ratio) and to determine the expression of the genes encoding pro- and anti-inflammatory cytokines using real-time PCR. The relative counts of CD68-, CD86-, and MHC II-positive cells in the lung tissue were also evaluated using flow cytometry. The w/d ratio was higher when the dose of 15 mg/kg of body weight was used (p = 0.0228, ordinary one-way Anova). Вlood lymphocyte counts were decreased (p = 0.0019, ordinary one-way Anova), and neutrophil counts were increased (p = 0.0021, ordinary one-way Anova) upon administration of both doses. The counts of CD86- (p = 0.0014, ordinary one-way Anova) and MHC II-positive cells (p = 0.0050, ordinary one-way Anova) increased after LPS administration. The IL10 gene expression was significantly increased upon administration of the dose of 15 mg/kg (p = 0.0024, ordinary oneway Anova), while the IL4 expression (p = 0.0194, ordinary one-way Anova) was decreased upon administration of the dose of 7.5 mg/kg. Thus, intranasal LPS administration can be used to model ARDS in the Sprague-Dawley rats. Administration of the high dose leads to the rapid development of inflammation in the lung.