Interplay Between Pulmonary Membrane Properties and Lung Disease: A Study of Seven Bottlenose Dolphins

Pneumonia is the leading cause of morbidity and mortality of bottlenose dolphins Tursiops truncatus. We investigate a series of rare and opportunistic samples of pulmonary surfactant membranes (PSMs) extracted from lungs of seven dolphins in the care of the U.S. Navy Marine Mammal Program. We found a striking correlation between PSM structure, lipidome, and mechanical properties with the severity of lung injury. Specifically, lipidomics reveals exacerbated contents of cardiolipins, confirming a result obtained for terrestrial mammals afflicted by experimental pneumonia. Employing a battery of X-ray scattering, atomic force, and electron microscopy, we evaluate how the altered lipid composition impairs the structural integrity of the PSM and leads to dehydration and enhanced rigidity. Our findings demonstrate that the function of pulmonary surfactant membranes goes far beyond lowering alveolar surface tension, regulating their biochemical and biophysical properties with lung pathology progression. This knowledge will be useful to the development of future diagnostics and therapeutics of respiratory diseases targeting lung membranes.