In vitro and in vivo effects of unsaturated fatty acids on Schistosoma mansoni and S. haematobium lung-stage larvae

J Parasitol. 2005 Oct;91(5):1094-102. doi: 10.1645/GE-514R.1.


Incubation of Schistosoma mansoni lung-stage larvae in 90% corn oil for 6 hr was shown to elicit exposure of their, otherwise masked, apical membrane antigens to binding of anti-schistosome antibodies in the indirect membrane immunofluorescence test (IF). The possibility that unsaturated fatty acids (FA) are responsible for this effect was herein supported by IF data on ex vivo lung-stage larvae of S. mansoni and S. haematobium incubated for 1/2-2 hr with 80% corn oil, 50% olive oil, or 10-20 microM arachidonic acid. Treatment with unsaturated FA followed by filipin staining for cholesterol visualization indicated that unsaturated FA do not induce exposure of schistosomular surface membrane antigens via extraction of surface membrane cholesterol. Evidence using inhibitors and stimulators of neutral sphingomyelinase suggested that unsaturated FA perhaps activate worm tegument-bound neutral sphingomyelinase, leading to sphingomyelin hydrolysis and changes in surface membrane fluidity. Larval apical membrane antigens are, thus, allowed to diffuse freely in the plane of the membrane and bind specific antibodies in IE Excessive sphingomyelin hydrolysis might explain why high FA concentrations or long incubation periods eventually lead to larval death. The significant decrease (P < 0.01) in S. mansoni and increase (P < 0.02) in S. haematobium worm recovery in BALB/c mice given unsaturated FA-high and -poor diets, respectively, indicated these findings have in vivo relevance and led to the proposal that unsaturated FA likely plays a role in natural attrition of S. mansoni and S. haematobium lung-stage larvae.

MeSH terms

  • Animals
  • Antigens, Helminth / immunology
  • Antigens, Surface / immunology
  • Cholesterol / analysis
  • Cricetinae
  • Dietary Fats, Unsaturated / administration & dosage*
  • Dietary Fats, Unsaturated / pharmacology
  • Enzyme Activation / drug effects
  • Fatty Acids, Unsaturated / administration & dosage
  • Fatty Acids, Unsaturated / pharmacology*
  • Filipin
  • Fluorescent Antibody Technique, Indirect
  • Larva / drug effects
  • Larva / enzymology
  • Larva / immunology
  • Lung / parasitology*
  • Male
  • Mesocricetus
  • Mice
  • Mice, Inbred BALB C
  • Random Allocation
  • Schistosoma haematobium / drug effects*
  • Schistosoma haematobium / enzymology
  • Schistosoma haematobium / immunology
  • Schistosoma mansoni / drug effects*
  • Schistosoma mansoni / enzymology
  • Schistosoma mansoni / immunology
  • Schistosomiasis haematobia / diet therapy
  • Schistosomiasis haematobia / parasitology
  • Schistosomiasis mansoni / diet therapy
  • Schistosomiasis mansoni / parasitology
  • Sphingomyelin Phosphodiesterase / antagonists & inhibitors
  • Sphingomyelin Phosphodiesterase / drug effects
  • Sphingomyelin Phosphodiesterase / metabolism
  • Sphingomyelins / metabolism
  • Staining and Labeling / methods


  • Antigens, Helminth
  • Antigens, Surface
  • Dietary Fats, Unsaturated
  • Fatty Acids, Unsaturated
  • Sphingomyelins
  • Filipin
  • Cholesterol
  • Sphingomyelin Phosphodiesterase