Summary
Objectives: Epidemiological surveys have shown that the
incidence of inflammatory bowel
disease (IBD) is relatively high
in developed countries but relatively low in countries with poor
sanitation and dense populations. Good hygiene and low parasitic
infections increase the susceptibility of individuals to IBD. The goal
of the present study was to assess the immune characteristics of hosts
infected with Trichinella spiralis(T. spiralis ) and the
relationship between intestinal worms and IBD. The ability of T.
spiralis infection to ameliorate the effects ofCitrobacter rodentium(C. rodentium ) in a mouse
IBD animal model was assessed, and the possible immunological mechanism
associated with this prevention and treatment of IBD was evaluated.
Materials and Methods: In the present study, 36 male BALB/c
mice aged 6-8 weeks were randomly divided into four groups: the control
group (PBS), the T. spiralis infection group (TS), the C.
rodentium -induced colon inflammation model group (CR) and the T.
spiralis pre-infected and C. rodentium induced colitis group
(TS+CR). The mice were sacrificed 7 and 14 days after the establishment
of the model. The changes in various colitis indicators were used to
investigate the effect of T. spiralis infection on the C.
rodentium -induced mouse CD model.
Results: The results showed that the weight, DAI score, and
macroscopic and microscopic colon damage in the TS+CR group was
significantly decreased compared with that observed in the CR group.
Flow cytometry results revealed that T. spiralis infection could
reduce the expression of IFN-γ, IL-17 and IL-12 and increase that of
IL-4 and IL-10 in colitis mice. Compared with that observed in the
control group, the number of
CD4+CD25+Foxp3+regulatory
T cells (Tregs) in the spleens and mesenteric lymph nodes (MLNs) of mice
in the TS group was increased (P <0.01). Compared with
that observed in the TS group mice, the expression of
CD4+CD25+Foxp3+Tregs
in the spleens and MLNs of the
TS+CR group mice was decreased (P <0.05). ELISA results
revealed that compared with the control group, the TS group produced a
strong IgG1 response (P <0.001) and low level of IgG2a
response (P >0.05), while increased expression of
IgG2a in serum was detected in the CR group mice
(P <0.05).
Conclusion: The results of the present study demonstrated thatT. spiralis -infected mice induced balanced Th2 immune responses
that balanced Th1 immune responses stimulated by C. rodentium to
ameliorate intestinal inflammation.
Key words: Trichinella spiralis ; Citrobacter
rodentium ; inflammatory bowel disease