Integrin αDß2 (CD11d/CD18) mediates experimental malaria-associated acute respiratory distress syndrome (MA-ARDS).

BACKGROUND: Malaria-associated acute respiratory distress syndrome (MA-ARDS) is a potentially lethal complication of clinical malaria. Acute lung injury in MA-ARDS shares features with ARDS triggered by other causes, including alveolar inflammation and increased alveolar-capillary permeability, leading to leak of protein-rich pulmonary oedema fluid. Mechanisms and physiologic alterations in MA-ARDS can be examined in murine models of this syndrome. Integrin αDß2 is a member of the leukocyte, or ß2 (CD18), sub-family of integrins, and emerging observations indicate that it has important activities in leukocyte adhesion, accumulation and signalling. The goal was to perform analysis of the lungs of mice wild type C57Bl/6 (a D (+/+) ) and Knockout C57Bl/6 (a D (-/-) ) with malaria-associated acute lung injury to better determine the relevancy of the murine models and investigate the mechanism of disease. METHODS: C57BL/6 wild type (a D (+/+) ) and deficient for CD11d sub-unit (a D (-/-) ) mice were monitored after infection with 10(5) Plasmodium berghei ANKA. CD11d subunit expression RNA was measured by real-time polymerase chain reaction, vascular barrier integrity by Evans blue dye (EBD) exclusion and cytokines by ELISA. Protein and leukocytes were measured in bronchoalveolar lavage fluid (BALF) samples. Tissue cellularity was measured by the point-counting technique, F4/80 and VCAM-1 expression by immunohistochemistry. Respiratory function was analysed by non-invasive BUXCO and mechanical ventilation. RESULTS: Alveolar inflammation, vascular and interstitial accumulation of monocytes and macrophages, and disrupted alveolar-capillary barrier function with exudation of protein-rich pulmonary oedema fluid were present in P. berghei-infected wild type mice and were improved in αDß2-deficient animals. Key pro-inflammatory cytokines were also decreased in lung tissue from α D (-/-) mice, providing a mechanistic explanation for reduced alveolar-capillary inflammation and leak. CONCLUSIONS: The results indicate that αDß2 is an important inflammatory effector molecule in P. berghei-induced MA-ARDS, and that leukocyte integrins regulate critical inflammatory and pathophysiologic events in this model of complicated malaria. Genetic deletion of integrin subunit αD in mice, leading to deficiency of integrin αDß2, alters lung inflammation and acute lung injury in a mouse model of MA-ARDS caused by P. berghei.

Does the use of recombinant AAV2 in pulmonary gene therapy damage lung function?

Forty-eight BALB/c mice were divided into two groups of 24 animals each. In the control group (CTRL) saline was intratracheally instilled, while the virus group (VR) received rAAV2-GFP (4 x 10(9) particles). These groups were subdivided into four sub-groups (n=6). Pulmonary mechanical parameters were analyzed after 3 weeks (VR1d3w) and at 1 (VR2d1w), 2 (VR2d2w) and 3 weeks (VR2d3w) after a second AAV2 dose. Fractions of the area of alveolar collapse and the amount of polymorpho- and mononuclear cells were determined by point-counting technique. Viral transduction was evaluated by immunohistochemistry. Lung mechanical data were similar in all groups. However, there was an increase in airway and lung parenchyma cellularity and in the fraction of area of alveolar collapse in the VR2d2w group, which nonetheless decreased with time. There was no evidence of apoptosis in any group. In conclusion, the gene transfer vector AAV2 induces, in the lung, a discrete inflammatory reaction that does not affect either baseline lung mechanics or airway hyperresponsiveness.