Mucosal cytokine and antigen‐specific responses to Cryptosporidium parvum in IL‐12p40 KO mice

Abstract

Studies of cellular immune responses to Cryptosporidium parvum have been limited in part by lack of suitable animal models. IL-12p40(-/-)mice are susceptible to initial infection with C. parvum but recover within 2 weeks, rendering the animals resistant to reinfection. Because the host responses that determine duration and severity of primary infection are not yet understood, we studied the cellular immune response to primary infection with C. parvum in IL-12p40(-/-)mice and also explored possible mechanisms for this response. Female IL-12p40(-/-)mice were inoculated with 10,000 oocysts. Uninfected age-matched mice served as controls. At different time intervals following exposure to oocysts, mice were sacrificed and their intestine, spleen, and mesenteric lymph node tissues were harvested. Cellular immune responses to C. parvum were characterized. Infection of IL-12p40(-/-)mice induced changes in the gene expression of the cytokines IFN-gamma, IL-4, IL-15, IL-18, TNF-alpha and TGF-beta during primary infection. There was also a significant increase in total numbers of lymphocytes and CD19/CD62L-expressing cells in mesenteric lymph nodes. These MLN cells exhibited increased antigen-specific proliferation and cytokine production (IL-6 and IFN-gamma) levels when stimulated in vitro. These observations delineate the cellular immune responses during acute C. parvum infection of the IL-12p40(-/-)mouse model.

MyD88-Dependent Pathways Mediate Resistance toCryptosporidium parvumInfection in Mice

“…In other parasitic infections, IL-12 production by dendritic cells or macrophages in response to TLR activation is believed to play a crucial role in IFN-␥ production (14). It is possible that similar mechanisms may be operative in C. parvum infection, particularly since IL-12 is known to be important in immune responses to this parasite (12,40). However, the finding that mice deficient in both IFN-␥-and MyD88-dependent pathways have more-severe infection than those deficient in MyD88 alone suggests that MyD88-independent pathways may be involved in IFN-␥-mediated innate resistance to C. parvum infection.…”

Validation of IMP Dehydrogenase Inhibitors in a Mouse Model of Cryptosporidiosis

“…Here, we report the antiparasitic activity of our eight most promising compounds in the interleukin-12 (IL-12) knockout mouse model. Infection is confined to the intestine in this model and resolves in 2 weeks, which is similar to acute human cryptosporidiosis (51). One compound, P131, displays greater antiparasitic activity than paromomycin, validating CpIMPDH as a target.…”

“…In vivo antiparasitic activity was evaluated in the IL-12 knockout mouse model of acute disease (51,55). IL-12 knockout mice are highly susceptible to C. parvum.…”

“…The anticryptosporidial activity of the CpIMPDH inhibitors was assessed in the IL-12 knockout mouse model that resembles the acute human disease (51,55). The protocol was approved by the Institutional Animal Care and Use Committees of Emory University, the Atlanta VA Medical Center, and Brandeis University.…”

Oral Immunization with AttenuatedSalmonella entericaSerovar Typhimurium EncodingCryptosporidium parvumCp23 and Cp40 Antigens Induces a Specific Immune Response in Mice

“…C57BL/6 interleukin-12p40 Ϫ/Ϫ mice, used for DNA vaccine work in our laboratory, are generally too susceptible to Salmo- nella infection, even with attenuated strains, to tolerate the high doses needed for effective inoculation (19,21). We therefore opted to use an alternative mouse model, C57BL/6 IL-18KO background, previously used in this laboratory (7). It offers a number of advantages essential for immunological studies such as a high level of susceptibility to C. parvum infection, resolution of the infection, resistance to reinfection, and development of a mixed Th1/Th2 mucosal cytokine response (6, 7).…”