Tryptophan metabolism and vitamin B₆nutritional status in patients with schistosomiasis mansoni and in infected mice

Abstract

Patients infected with Schistosoma mansoni showed an abnormal response to a test dose of tryptophan, with little increase in the urinary excretion of kynurenine, hydroxykynurenine, xanthurenic and kynurenic acids, N1-methyl nicotinamide, methyl pyridone carboxamide, 5-hydroxytryptamine or 5-hydroxyindoleacetic acid. In contrast to previous reports, this is different from the pattern of tryptophan metabolism seen in vitamin B6 deficiency. Furthermore, the patients' plasma concentrations of pyridoxal phosphate were within the reference range, and supplementation for 5 days with 20 mg vitamin B6/day did not affect tryptophan metabolism. Treatment with a single dose of Praziquantel resulted in a substantial restoration of normal tryptophan metabolism. In mice infected with S. mansoni there was a similar impairment of tryptophan metabolism, as shown by considerably reduced formation of 14CO2 after the administration of a tracer dose of [14C]tryptophan. Again, the administration of vitamin B6 supplements did not correct tryptophan metabolism in the mice. Treatment with Praziquantel resulted in substantial restoration of the production of 14CO2 from [14C]tryptophan. There was no evidence of vitamin B6 deficiency (as determined by erythrocyte aspartate aminotransferase activation coefficient) associated with infection in the mice, although there was a redistribution of pyridoxal phosphate between tissues, with a reduction in the concentration of liver, spleen and kidney, and an increase in skeletal muscle.

Metabonomic investigations in mice infected with Schistosoma mansoni : An approach for biomarker identification

“…Furthermore, the elevation of tryptophan noted in the current study is consistent with a previous study, documenting impaired tryptophan metabolism associated with S. mansoni infections in humans and mice (38). The reduction in alanine excretion observed in the S. mansoni-infected mice may imply that conversion of pyruvate to alanine by alanine aminotransferase is depressed.…”

Echinococcus granulosus Infection Results in an Increase in Eisenbergiella and Parabacteroides Genera in the Gut of Mice

“…Based on pathway impact analysis, we found that tryptophan metabolism was decreased in the E. granulosus infection group. In mice infected with schistosomes , tryptophan or compounds from tryptophan metabolism were up-regulated and increased in urine which indicate possible problems in tryptophan metabolism in these infected animals ( Njagi et al, 1992 ; Wang et al, 2004 ).…”

Therapeutic and Operational Profiles of Metrifonate and Praziquantel in Schistosoma haematobium Infection

“…However, it must be underlined that except involvement of female genital organs, the other disease manifestations are relatively rare in S. haematobium. Interestingly, praziquantel was able to restore an abnormal tryptophan metabolism in patients as well as in animals [47] and to reduce chromosomal damage in urothelial cells [48]. The latter finding should have important implications since S. haematobium associated bladder disease is considered to promote the development of cancer of the bladder.…”