Fatty acid and cholesterol synthesis in mice infected with the tapeworm Hymenolepis microstoma

Effects of excessive dietary zinc or zinc/cadmium and tapeworm infection on the biochemical parameters in rats

The main objective of this study was to determine which biochemical blood parameters can serve as indicators of Zn or Zn/Cd burden and tapeworm infection. This study was performed on 44 Wistar male rats during a 6-week period, when rats were or were not fed a zinc/cadmium rich diet and were or were not infected with tapeworms (Hymenolepis diminuta). Total protein, albumin, urea, glucose, triacylglycerols, non-esterified fatty acids, cholesterol, alkaline phosphatase, aspartate aminotransferase, uric acid, Mg, Ca, P and Zn levels were analysed. Control rats with tapeworm infection had significantly higher (p ≤ 0.05) total protein, urea and phosphorus concentrations than did rats unaffected by any experimental factor. Rats given overdoses of zinc lactate exhibited significantly lower glucose levels than did the other rats, especially those infected with tapeworms. Low glucose level in uninfected rats indicate a Zn overdose; high doses of zinc lactate likely decrease levels of glucose via cortisol, which is released during stress. Rats fed the Zn/Cd hyperaccumulating plant Arabidopsis halleri and infected with tapeworms had significantly higher (p ≤ 0.01) cholesterol and urea levels but lower zinc, triacylglycerol, and alkaline phosphatase levels than did rats fed the same diet but free of tapeworms. The increase of alkaline phosphatase level in uninfected rats may indicate both Zn/Cd burden and rat liver damage. Overall, this study not only supports the theory that H. diminuta can serve as a promising model for helminth therapy of the host mammal but also confirmed that this tapeworm is capable to protect somehow the host organism from the harmful effects of heavy metals.

Role of cholesterol in parasitic infections

The requirement of cholesterol for internalization of eukaryotic pathogens like protozoa (Leishmaniasis, Malaria and Toxoplasmosis) and the exchange of cholesterol along with other metabolites during reproduction in Schistosomes (helminths) under variable circumstances are poorly understood. In patients infected with some other helminthes, alterations in the lipid profile have been observed. Also, the mechanisms involved in lipid changes especially in membrane proteins related to parasite infections remain uncertain. Present review of literature shows that parasites induce significant changes in lipid parameters, as has been shown in the in vitro study where substitution of serum by lipid/cholesterol in medium and in experimental models (in vivo). Thus changes in lipid profile occur in patients having active infections with most of the parasites. Membrane proteins are probably involved in such reactions. All parasites may be metabolising cholesterol, but the exact relationship with pathogenic mechanism is not clear. So far, studies suggest that there may be some factors or enzymes, which allow the parasite to breakup and consume lipid/cholesterol. Further studies are needed for better understanding of the mechanisms involved in vivo. The present review analysis the various studies till date and the role of cholesterol in pathogenesis of different parasitic infections.

Phosphorus metabolites of liver from mice infected with Hymenolepis microstoma

31P NMR in vivo spectra of mouse livers infected with Hymenolepis microstoma for 130 or 265 days showed modifications in phosphorus-containing metabolite ratios when compared to those of normal liver. After 130 days of infection the metabolite ratio of inorganic phosphate (Pi)/beta ATP significantly increased whereas that of phosphocreatine (PCr)/beta ATP significantly decreased. In older, 265 day infections, the increase in Pi/beta ATP and decrease in PCr/beta ATP persisted. Changes in the group infected for 130 days were accompanied by lowered pH. Analysis of liver extracts from mice with 130-day-old. H. microstoma revealed significantly lower concentrations of Pi, ATP and ADP compounds. In those from mice infected for 265 days the concentration of Pi remained low whereas concentrations of ATP and ADP increased to levels in between those of controls and the 130-day-old infection. In addition, levels of phosphorylethanolamine (PE) and of an unknown metabolite significantly increased in this latter group. Worm extracts contained high levels of glycerophosphorylcholine (GPC), Pi, fructose 1,6-diphosphate (FDP), PE, diphosphodiesters (DPDE), phosphorylcholine (PC) and glycerolphosphorylethanolamine (GPE) in order of declining concentrations, respectively.