Effects of acute hypercapnia with and without acidosis on lung inflammation and apoptosis in experimental acute lung injury.

We investigated the effects of acute hypercapnic acidosis and buffered hypercapnia on lung inflammation and apoptosis in experimental acute lung injury (ALI). Twenty-four hours after paraquat injection, 28 Wistar rats were randomized into four groups (n=7/group): (1) normocapnia (NC, PaCO2=35-45 mmHg), ventilated with 0.03%CO2+21%O2+balancedN2; (2) hypercapnic acidosis (HC, PaCO2=60-70 mmHg), ventilated with 5%CO2+21%O2+balancedN2; and (3) buffered hypercapnic acidosis (BHC), ventilated with 5%CO2+21%O2+balancedN2 and treated with sodium bicarbonate (8.4%). The remaining seven animals were not mechanically ventilated (NV). The mRNA expression of interleukin (IL)-6 (p=0.003), IL-1ß (p<0.001), and type III procollagen (PCIII) (p=0.001) in lung tissue was more reduced in the HC group in comparison with NC, with no significant differences between HC and BHC. Lung and kidney cell apoptosis was reduced in HC and BHC in comparison with NC and NV. In conclusion, in this experimental ALI model, hypercapnia, regardless of acidosis, reduced lung inflammation and lung and kidney cell apoptosis.

Bone marrow-derived mononuclear cell therapy attenuates silica-induced lung fibrosis.

This study tests the hypothesis that bone marrow-derived mononuclear cell (BMDMC) therapy may reduce lung inflammation and fibrosis leading to an improvement in respiratory mechanics in a murine model of silicosis. 52 female C57BL/6 mice were randomly assigned into four groups. In the silica group (SIL), silica suspension (20 mg/50 µL in saline) was intratracheally instilled. In the control animals, 50 µL saline was administered intratracheally. At 1 h, the control and SIL groups were further randomised, receiving BMDMC (2×106 i.v. control-cell and SIL-cell) or saline (50 µL i.v. control and SIL). BMDMC were obtained from male donor mice. At day 15, lung mechanics, histology, and the presence of Y chromosome, interleukin (IL)-1ß, IL-1α, IL-1 receptor antagonist (IL-1RN), IL-1 receptor type 1, transforming growth factor (TGF)-ß and caspase-3 mRNA expressions in lung tissue were analysed. In the SIL-cell group, the fraction area of granuloma, the number of macrophages and the collagen fibre content were reduced, yielding improved lung mechanics. The presence of male donor cells in lung tissue was not confirmed using detection of Y chromosome DNA. Nevertheless, caspase-3, IL-1ß, IL-1α, IL-1RN and TGF-ß mRNA expression diminished after cell therapy. In conclusion, BMDMC acted on inflammatory and fibrogenic processes improving lung function through paracrine effects.

Does the use of recombinant AAV5 in pulmonary gene therapy lead to lung damage?

This study investigated whether repeated administration of recombinant adeno-associated virus type 5 (rAAV5) to the airways induces inflammatory processes in the lungs of BALB/c-mice, with mechanical and histologic changes. Saline was instilled intratracheally in the control group, and rAAV5-green fluorescence protein (GFP) (4x10(11)particles) in the virus group (VR). These groups were subdivided into four subgroups: one dose analyzed 3 weeks later (VR1d3w) and two doses analyzed 1 (VR2d1w), 2 (VR2d2w) and 3 weeks (VR2d3w) after the second dose. Lung morphometry, mechanical parameters, airway responsiveness, rAAV5-GFP transduction and the expression of inflammatory cytokines were investigated. No significant differences in lung mechanics, airway responsiveness, and morphometry were observed. Re-administration of rAAV5 vector resulted in a decrease in GFP mRNA expression in the VR2d3w group. There was no evidence of inflammatory response or apoptosis in any group. rAAV5 did not induce an inflammatory process, mechanical or morphometric changes in the lungs. AAV5 may be an appropriate vector for lung gene therapy.

Atrial natriuretic peptide modulates cystic fibrosis transmembrane conductance regulator chloride channel expression in rat proximal colon and human intestinal epithelial cells.

The cystic fibrosis transmembrane conductance regulator (CFTR) is one of the most intensively investigated Cl- channels. Different mutations in the CFTR gene cause the disease cystic fibrosis (CF). CFTR is expressed in the apical membrane of various epithelial cells including the intestine. The major organ affected in CF patients is the lung, but it also causes an important dysfunction of intestinal ion transport. The modulation of CFTR mRNA expression by atrial natriuretic peptide (ANP) was investigated in rat proximal colon and in human intestinal CaCo-2 cells by RNase protection assay and semi-quantitative reverse transcriptase PCR techniques. Groups of rats subjected to volume expansion or intravenous infusion of synthetic ANP showed respective increases of 60 and 50% of CFTR mRNA expression in proximal colon. CFTR mRNA was also increased in cells treated with ANP, reaching a maximum effect at 10(-9) M ANP, probably via cGMP. ANP at 10(-9) M was also able to stimulate both the CFTR promoter region (by luciferase assay) and protein expression in CaCo-2 cells (by Western blot and immunoprecipitation/phosphorylation). These results suggested the involvement of ANP, a hormone involved with extracellular volume, in the expression of CFTR in rat proximal colon and CaCo-2 intestinal cells.