Sepsis by using Cecal Ligation and Single Puncture Causes Alveolar Space Enlargement in LPA2 Knockout Mice
Journal of Allergy & Therapy
Lysophosphatidic acid (LPA) plays a dual-function in lung inflammatory diseases. LPA receptors contribute to the pathogenesis of asthma, acute lung injury, and fibrosis. Here, we investigate the role of LPA receptor type 2 (LPA 2 ) in sepsis-induced lung inflammation and injury. Sepsis was induced using cecal ligation and single puncture (CLP) with 27 gauge needle. Plasma interleukin-6 (IL-6) and KC levels were elevated in septic wild type and LPA 2 -/-mice, while septic LPA 2 -/-mice reduces
... 2 -/-mice reduces plasma KC, not IL-6 levels, compared to septic wild type mice. Bronchoalveolar lavage (BAL) KC levels increased in septic wild type and LPA 2 -/-mice, while the sepsis had no effect on BAL IL-6 levels, protein leak, and inflammatory cell infiltration in the lungs in wild type and LPA 2 -/-mice. Hematoxylin and eosin (H&E) staining revealed that septic LPA 2 -/-mice aggravated alveolar space enlargement. Western blotting analysis of lung tissues demonstrate that the level of cortactin, an F-actin binding protein, was decreased in septic LPA 2 -/-mice, when compared to wild type mice. The level of immunoglobulin G (IgG) in BAL fluids significantly increased in septic LPA 2 -/-mice, when compared to septic wild type mice and sham mice. Furthermore, we found that sham and septic LPA 2 -/-mice increased surfactant proteins B, C, and D (SP-B, SP-C, and SP-D) expression in lungs, while SP-A levels in lungs was decreased in sham and septic LPA 2 -/-mice. These results suggest LPA 2 may regulate cortactin and surfactant protein expression in the lung. LPA 2 and its downstream signaling may play a protective role against sepsis induced emphysema like disease. Figure 5: Septic LPA 2 -/-mice altered surfactant protein levels in the lung -A. Four group mice were sacrificed at 24 h and lung tissues were lysed. Equal amount of lung tissue proteins (20 μg) were subjected to 12 % SDS/PAGE gel and surfactant protein levels were determined by Western blotting with antibodies to surfactant protein A-D and β-actin. B-E. Intensities of surfactant protein and β-actin bands were analyzed by ImageJ software. Data represent mean ± SD and n = 3-4. *p < 0.05 vs sham wild type mice. *p < 0.05 vs septic wild type mice.