Objective: To explore the effects of STAT4 and STAT6 on the development of worms and granuloma formation in mice infected with Schistosoma japonicum.
Methods: All the intact BALB/cJ mice and STAT4(-/-), STAT6(-/-) mice with the same genetic background were infected with 25 S. japonicum cercariae. All the mice were sacrificed on the 42nd day after infection and the worms were collected. The total number of worms and the mean number of worm pairs were counted. The liver of each mouse was removed for the count of eggs, the histological examination and the determination of the size of single-egg granulomas in the liver.
Results: No significant differences were found in the total number of worms, the number of worm pairs and the number of eggs per pair of worms in the liver among STAT4(-/-), STAT6(-/-) and BALB/cJ mice. The size of single-egg granulomas in the liver of STAT6(-/-) mice (213.3 +/- 68.6) microm was significantly smaller than that in the liver of normal BALB/cJ mice (319.5 +/- 71.9) microm (P < 0.05). The liver granulomas were not well formed and the liver fibrosis decreased in STAT6(-/-) mice.
Conclusions: STAT4 or STAT6 deficiency has no conspicuous effect on the development and fecundity of S. japonicum. STAT6 plays an important role for the granuloma formation and liver fibrosis.