Effects of pulmonary inhalation on hyperpolarized krypton-83 magnetic resonance T1 relaxation.

The (83)Kr magnetic resonance (MR) relaxation time T(1) of krypton gas in contact with model surfaces was previously found to be highly sensitive to surface composition, surface-to-volume ratio, and surface temperature. The work presented here explored aspects of pulmonary (83)Kr T(1) relaxation measurements in excised lungs from healthy rats using hyperpolarized (hp) (83)Kr with approximately 4.4% spin polarization. MR spectroscopy without spatial resolution was applied to the ex vivo lungs that actively inhale hp (83)Kr through a custom designed ventilation system. Various inhalation schemes were devised to study the influence of anatomical dead space upon the measured (83)Kr T(1) relaxation times. The longitudinal (83)Kr relaxation times in the distal airways and the respiratory zones were independent of the lung inhalation volume, with T(1) = 1.3 s and T(1) = 1.0 s, depending only on the applied inhalation scheme. The obtained data were highly reproducible between different specimens. Further, the (83)Kr T(1) relaxation times in excised lungs were unaffected by the presence of up to 40% oxygen in the hp gas mixture. The results support the possible importance of (83)Kr as a biomarker for evaluating lung function.

Alpha-4/beta-1 and alpha-L/beta-2 integrins mediate cytokine induced lung leukocyte-epithelial adhesion and injury.

BACKGROUND AND PURPOSE: Injury to the alveolar epithelium is a critical feature of acute lung injury (ALI). Using a cytokine model of ALI we demonstrated previously that newly recruited mononuclear phagocytes (MNP) contributed to lung inflammation and injury. We hypothesized that cytokines delivered into the alveolar airspace would have multiple effects on the lung that may contribute to lung injury. EXPERIMENTAL APPROACH: Intratracheal cytokine insufflation and leukocyte adoptive transfer in vivo were combined with in vitro analyses of lung epithelial cell-MNP adhesion and injury. Lung inflammatory injury was assessed by histology, leukocyte infiltration, and release of LDH and RAGE. KEY RESULTS: Cytokine insufflation was associated with apparent MNP-epithelial adhesion, up-regulation of alveolar ICAM-1 and VCAM-1, and the release of LDH and RAGE into the bronchoalveolar lavage. Insufflation of small molecule integrin antagonists suppressed adhesion of MNP and modulated release of LDH and RAGE. Adoptive transfer of MNP purified from cytokine insufflated lungs into leukopenic rats demonstrated the requirement of MNP for release of LDH that was not induced by cytokine alone. Corroboration that disrupting the ICAM/LFA1 interaction or the VCAM/VLA4 interaction blocked MNP-epithelial cell interaction and injury was obtained in vitro using both blocking monoclonal antibodies and the small molecule integrin antagonists, BIO5192 and XVA143. CONCLUSIONS AND IMPLICATIONS: MNP recruited following cytokine insufflation contributed to lung injury. Further, integrin antagonists reduced alveolar epithelial cell injury induced during lung inflammation. Intratracheal delivery of small molecule antagonsists of leukocyte-epithelial adhesion that prevent lung injury may have significant clinical utility.

Characteristics of pulmonary surfactant in adult respiratory distress syndrome associated with trauma and shock.

Broncho-alveolar lavage fluid was obtained from a 24-year-old man who developed the adult respiratory distress syndrome one day after massive trauma and hemorrhagic shock. The lungs were available 3 days later when organ transplantation was performed. When the various fractions of the lavage material obtained by centrifugation, including the purified surface-active lipid-protein aggregates, were examined on the film balance, they revealed the usual minimal surface tension of 16 to 18 dyne per cm at 37 degrees C, but the compressibility of the films from the lungs with adult respiratory distress syndrome was 5 to 10 times higher than the normal range. This suggests that surfactant films in the adult respiratory distress syndrome are less responsive to stress, and that as a result, a loss of film elasticity may contribute to the abnormal pressure-volume relationships observed with the intact lung. Changes in the lipid-to-protein ratios of the purified lipid-protein aggregates were also found, as indicated by the recovery of 3 lipid-protein aggregates with different isopycnic densities from the lung with adult respiratory distress syndrome; only one major aggregate could be recovered from the lavages of normal lungs.