title: Effects of aerobic exercise on lipid-effector molecules of the innate immune response.
abstract: BACKGROUND
  Consistent, moderate-to-vigorous-intensity exercise has been associated with a lower risk of upper respiratory tract infection (URI). However, the molecular basis for this apparent protection has not yet been fully resolved. Host-derived lipids such as cholesteryl esters (CE) have emerged as important effector molecules of innate defense against infections. Here, we compared antimicrobial CE in nasal fluid before and after moderate-to-vigorous exercise between active and inactive subjects.
  
  
  METHODS
  Nasal fluid was collected from 14 healthy, recreationally active subjects (32 ± 11 yr, 7 men and 7 women) and 14 healthy, inactive subjects (25 ± 3 yr, 7 men and 7 women) before and after treadmill exercise at 70% heart rate reserve. Nasal fluid was analyzed for lysozyme, cholesteryl linoleate (CL), cholesteryl arachidonate (CA), and albumin (Alb) concentrations.
  
  
  RESULTS
  Baseline concentrations (mean ± SEM, inactive vs active) of lysozyme (117.7 ± 31.1 vs 122.9 ± 15.5 μg·mL), CL + CA (15.3 ± 1.8 vs 26.2 ± 10.05 μg·mL), and Alb (156.6 ± 54.5 vs 126.9 ± 32.8 μg·mL) were similar to previously reported levels and did not differ significantly between study groups. However, postexercise, CL + CA concentration was significantly lower in inactive compared with active subjects (7.8 ± 1.5 vs 20.1 ± 4.8 μg·mL, P = 0.036) dropping below the antimicrobial effective range. Once adjusted to Alb concentrations, the changes were no longer significant, suggesting that plasma transudation accounted for the increased CA + CL concentration postexercise in the active group relative to the inactive group.
  
  
  CONCLUSIONS
  Moderate-to-vigorous aerobic exercise acutely decreases the antimicrobial CE response in inactive subjects but does not modify baseline levels of CE between active and inactive subjects. This suggests that compared with active individuals, inactive individuals may be at greater risk for upper respiratory tract infection immediately postexercise.
authors.affiliation: 1Department of Biological Sciences, California State University Los Angeles, Los Angeles, CA; and 2School of Kinesiology and Nutritional Sciences, California State University Los Angeles, Los Angeles, CA.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Kiwata
authors.forename: Rabin
authors.initials: R
authors.lastname: Anouseyan
authors.forename: Robert
authors.initials: R
authors.lastname: Desharnais
authors.forename: Andrew
authors.initials: A
authors.lastname: Cornwell
authors.forename: Nazareth
authors.initials: N
authors.lastname: Khodiguian
authors.forename: Edith
authors.initials: E
authors.lastname: Porter
mesh_terms: D000293:Adolescent; D000328:Adult; D000418:Albumins / Q000032:analysis; D002788:Cholesterol Esters / Q000032:analysis*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D007113:Immunity, Innate / Q000502:physiology*; D008297:Male; D009113:Muramidase / Q000032:analysis; D017817:Nasal Lavage Fluid / Q000737:chemistry* / Q000276:immunology; D010101:Oxygen Consumption / Q000502:physiology; D012141:Respiratory Tract Infections; D055815:Young Adult
chemical_list: D000418:Albumins; D002788:Cholesterol Esters; D009113:Muramidase