Humoral immune response in IL‐12 and IFN‐γ deficient mice after infection with Cryptosporidium parvum

Abstract

Infection with Cryptosporidium spp. causes diarrhoeal disease and has become an important medical and veterinary problem especially in the immunocompromised host. The importance of the adaptive immune response, with CD4+ T-lymphocytes being the major players, has been clearly demonstrated. The requirement of IL-12 and IFN-gamma identifies this response as a Th1-dominated reaction. IFN-gamma is also important in the early phase of the host-parasite interaction. We analysed the outcome of infection in IL-12p40 (IL-12KO) and IFN-gamma (GKO) deficient C57BL/6 mice after primary and secondary challenge with the parasite and, for the first time, we demonstrate the resulting Ig response in sera and vaginal lavages. Although showing differences in the extent and the time course both strains of mice were able to clear infection and developed an almost complete resistance to re-infection. While GKO mice mounted prolonged parasite-specific IgG and IgA responses after primary infection, in IL-12KO mice IgG and IgA titres dropped over time. Re-challenge of mice 5 weeks after primary infection led to a booster effect in Ig response despite the absence of oocyst shedding. The data from infection and re-challenge experiments suggest that in IL-12- or IFN-gamma-deficient mice the development of resistance involves other protective immune responses.

Dynamics of gut mucosal and systemic Th1/Th2 cytokine responses in interferon-gamma and interleukin-12p40 knock out mice during primary and challenge Cryptosporidium parvum infection

“…IL-12 prevented C. parvum infection through an IFN-g-induction in vivo (Urban et al, 1996). However, IFN-g is induced by the parasite even in IL-12KO mice, as shown in this study as well as previous ones (Ehigiator et al, 2005;Jakobi and Petry, 2008), indicating the presence of IL-12 independent factors that regulate the production of IFN-g in C. parvum infection. IL-18 is a potential candidate as it regulates IFN-g in the presence or absence of IL-12 and this cytokine also regulates Th2 immune responses (reviewed in Nakanishi et al, 2001).…”

“…In order to analyze the mechanisms conferring resistance towards infection with C. parvum, a re-challenge was set at 5 weeks (36 days) post primary infection. Mice were sacrificed on arbitrarily selected days, 1, 4, and 15, as no oocyst shedding was detected post re-challenge in both mouse models due to development of resistance (Jakobi and Petry, 2008). Distal ilea, spleen and mesenteric lymph nodes (MLN) were collected and kept in RNA stabilizing solution (RNAlater, Qiagen, Hilden, Germany) and stored at À70 1C until processing for RNA isolation.…”

“…Animals were fed sterile food and water ad libitum, kept in filter top cages and handled under a laminar flow. Genotyping of the breeding colonies was performed as described (Jakobi and Petry, 2008). All animal experimentation was licensed by the regional health authorities.…”

“…A similar number of uninfected mice were used as controls for each set of experiment. The oocyst shedding pattern in both animal models was considered, as previously described (Jakobi and Petry, 2008), in choosing the time points for tissue preparation. Mice were sacrificed on days 1, 3, 8, and 15 post primary infections of GKO mice representing the times of ''before start'', ''start'', ''peak'' and ''resolution'' of fecal oocyst shedding.…”

“…We have recently reported that after resolution of the primary infection a re-challenge of both GKO and IL-12KO mice led to a booster of systemic and mucosal antibody responses (Jakobi and Petry, 2008). However, the cytokines induced in vivo in recovered animals upon re-challenge have not been completely studied yet.…”