Joanna Floros, Ph.D Evan Pugh Professor, Departments of Cellular and Molecular Physiology, Pediatrics, and Obstetrics and Gynecology. The Pennsylvania State University, College of Medicine, Hershey, PA, U.S.A Surfactant Composition and Function 8 th World Hellenic Biomedical Congress

1. Characteristics of Surfactant What is surfactant? What is its composition? Where is it made? What is its structure? Surfactant 2. Function of surfactant

MAJOR CONSTITUENTS OF PULMONARY SURFACTANT PC (DSPC) Cholesterol PG PI Other lipids Protein PE Surfactant SP-A SP-B SP-C Proteins Unsaturated Other Proteins SP-D Pulmonary surfactant biochemically, is a lipoprotein complex that lines the internal surface of the alveoli. What is Pulmonary Surfactant and What is its Composition? 16:/16:0 PC

Fishman 2-19

SURFACTANT HETEROGENEITY AND LIFE CYCLE SMALL AGGREGATES LARGE AGGREGATES SURFACE FILM TUBULAR MYELIN LAMELLAR BODIES HYPOPHASE FLUID (SUPERNATANT) SP-A LB, TM, SP-A

1. Characteristics of Surfactant What is surfactant? What is its composition? Where is it made? What is its structure? Surfactant 2. Function of surfactant and/or surfactant components Lowering of surface tension. Innate host defense. Initiation of parturition (SP-A, a hormone?)

Functions of surfactant Stabilizes alveoli and prevents alveolar (lung) collapse with each exhalation by lowering the surface tension at the air-liquid surface. Surfactant components play a role in host defense and protect the lung from injuries or infections caused by inhaled microorganisms, particles, toxins, other. One of the protein component of surfactant (SP-A) may serve as a hormone in parturition. Surface tension Host defense Initiation of labor

J. Kending Air-Liquid Interface Without surfactantWith surfactant Surfactant

MAJOR CONSTITUENTS OF PULMONARY SURFACTANT PC (DSPC) Cholesterol PG PI Other lipids Protein PE Surfactant SP-A SP-B SP-C Proteins Unsaturated Other Proteins SP-D 16:0/16:0 PC

Functions of surfactant Stabilizes alveoli and prevents alveolar (lung) collapse with each exhalation by lowering the surface tension at the air- liquid surface. Surfactant components play a role in host defense and protect the lung from injuries or infections caused by inhaled microorganisms, particles, toxins, other. One of the protein component of surfactant (SP-A) may serve as a hormone in parturition. Surface tension Host defense Initiation of labor

INHIBITION SP-A LIPID StimulationInhibition Oxidant Production Splenocyte Proliferation Cell Surface Markers Cytokine Production NF-kB Activation Fibroblast Apoptosis Collagen and Collagenase Production SP-A PE SM PC PG PI STIMULATION CHOL PC PG PI INHIBITION SP-A PE SM CHOL SURFACTANT REGULATION OF IMMUNE CELLS STIMULATION

LARGE AGGREGATES TUBULAR MYELIN SP-A Cell Surface Markers; Cytokine Production; NF-kB Activation; Collagen and Collagenase Production Surfactant-relatedHost defense-related SP-A FUNCTION InnateAdaptive myr present Regulation of inflammatory processes Innate Immunity

Human SP-A Genes, and Variants Genes 6A 2 1A 0 C T P SP-A1 SP-A2 Variants The above variants have been shown to exhibit qualitative and quantitative differences. In addition environmental insults, such as ozone, appear to differentially alter their functional activity and thus contribute to individual differences in disease susceptibility.

Differences exist among SP-A variants in their ability to enhance phagocytosis of bacteria by alveolar macrophages in the presence or absence of environmental factors.

agar plate agar plate suspension suspension of bacteria alveolar macrophages alveolar macrophages SP-A SP-A phagocytosis wash off free bacteria slide preparation light microscopy analysis BAL BAL insect cells or insect cells or mammalian cells rat rat ozone EXPERIMENTAL APPROACH EXPERIMENTAL APPROACH

Microscopic view of live P. aeruginosa, phagocytized by rat alveolar macrophages in the presence or absence of human SP-A No SP-ASP-A R E S U L T S R E S U L T S

SP-A2 products exhibit higher phagocytic ability than SP-A1 § hSP-A vs. SP-A variants (insect) Phagocytic index: % of bacteria-positive AMs  the average # of bacteria per bacteria-positive AMs * SP-A2 vs. SP-A1 ; ** 6A 2 vs. 6A 4 ; *** hSP-A vs. 6A 4 (mammalian); (hSP-A: 25 µg/ml) Mikerov et al Bacteria: P.aeruginosa Mammalian expressed variants Phagocytic index (%) 1.56  g/ml n=5 ** *** * * SP-A2 1A 0 1A 6A 2 6A 4 SP-A1 hSP-A

Ability of SP-A variants to enhance phagocytosis by alveolar macrophages following exposure to ozone. 1A 0 > 1A 0 (SP-A2) 6A 4 = 6A 4 (SP-A1) 1A 0 /6A 4 > 1A 0 /6A 4 (SP-A2/SP-A1) Ozone-exposedUnexposed

Functions of surfactant Stabilizes alveoli and prevents alveolar (lung) collapse with each exhalation by lowering the surface tension at the air- liquid surface. Surfactant components play a role in host defense and protect the lung from injuries or infections caused by inhaled microorganisms, particles, toxins, other. One of the protein component of surfactant (SP-A) may serve as a hormone in parturition. Surface tension Host defense Initiation of labor

Increased levels of SP-A Fetal macrophages activate Increased levels of proinflammatory cytokines (i.e. IL-b1) NF-kB Increase expression of genes that cause myometrial contractibility activate Surfactant lipids (Arachidonate derivatives) P65 antagonizes progesterone receptor activation of genes that modulate uterine quiescence. Prostaglandin synthesis Fetal SP-A initiates labor

Summary Pulmonary surfactant, a lipoprotein complex, is essential throughout life for normal lung function, host defense, and other functions. Derangement in surfactant either through alterations in composition or modification (i.e. oxidation) can negatively affect normal lung function and host defense. Genetic differences in surfactant components may contribute to differences in disease risk among individuals.