Pulmonary surfactant is a highly surface-active mixture of proteins and lipids that is synthesized
and secreted in the alveoli by type II epithelial cells and is found in the fluid lining the alveolar
surface. The protein part of surfactant constitutes two hydrophilic proteins (SP-A and SP-D) that regulate
surfactant metabolism and have immunologic functions, and two hydrophobic proteins (SP-B and
SP-C), which play a direct role in the organization of the surfactant structure in the interphase and in
the stabilization of the lipid layers during the respiratory cycle. Several studies have shown that cigarette smoke seems to
affect, in several ways, both surfactant homeostasis and function. The alterations in surfactants’ biophysical properties
caused by cigarette smoking, contribute to the development of several smoking related lung diseases. In this review we
provide information on biochemical and physiological aspects of the pulmonary surfactant and on its possible association
with the development of two major chronic diseases of the lung known to be related to smoking, i.e. chronic obstructive
pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Additional information on the possible role of surfactant
protein alterations and/or dysfunction in the combination of these two conditions, recently described as combined
pulmonary fibrosis and emphysema (CPFE) are also provided.
Keywords: Pulmonary Surfactant, Surfactant Proteins, Chronic Obstructive Pulmonary Disease, Idiopathic Pulmonary Fibrosis,
Combined Pulmonary Fibrosis and Emphysema.
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