RESUMO
Current evidence indicates that the chronic inflammation observed in the intestines of patients with inflammatory bowel disease is due to an aberrant immune response to enteric flora. We have developed a lipid A-mimetic, CRX-526, which has antagonistic activity for TLR4 and can block the interaction of LPS with the immune system. CRX-526 can prevent the expression of proinflammatory genes stimulated by LPS in vitro. This antagonist activity of CRX-526 is directly related to its structure, particularly secondary fatty acyl chain length. In vivo, CRX-526 treatment blocks the ability of LPS to induce TNF-alpha release. Importantly, treatment with CRX-526 inhibits the development of moderate-to-severe disease in two mouse models of colonic inflammation: the dextran sodium sulfate model and multidrug resistance gene 1a-deficient mice. By blocking the interaction between enteric bacteria and the innate immune system, CRX-526 may be an effective therapeutic molecule for inflammatory bowel disease.
Assuntos
Adjuvantes Imunológicos/farmacologia , Anti-Inflamatórios não Esteroides/farmacologia , Glucosamina/análogos & derivados , Glucosamina/farmacologia , Doenças Inflamatórias Intestinais/patologia , Doenças Inflamatórias Intestinais/prevenção & controle , Lipídeo A/análogos & derivados , Lipídeo A/farmacologia , Receptores Imunológicos/antagonistas & inibidores , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/deficiência , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Adjuvantes Imunológicos/síntese química , Animais , Caproatos/química , Células Cultivadas , Colite/induzido quimicamente , Colite/genética , Colite/imunologia , Colite/prevenção & controle , Sulfato de Dextrana/toxicidade , Modelos Animais de Doenças , Feminino , Glucosamina/química , Células HeLa , Humanos , Doenças Inflamatórias Intestinais/genética , Doenças Inflamatórias Intestinais/imunologia , Lipopolissacarídeos/administração & dosagem , Lipopolissacarídeos/antagonistas & inibidores , Lipopolissacarídeos/farmacologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Camundongos Knockout , Monócitos/efeitos dos fármacos , Monócitos/imunologia , Monócitos/metabolismo , Receptores Imunológicos/metabolismo , Receptor 4 Toll-Like , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Three immunodominant leishmanial antigens (TSA, LmSTI1 and LeIF) previously identified in the context of host response to infection in infected donors and BALB/c mice, as well as their ability to elicit at least partial protection against Leishmania major infection in the BALB/c mouse model, were selected for inclusion into a subunit based vaccine. This is based on the premise that an effective vaccine against leishmaniasis (a complex parasitic infection) would require a multivalent cocktail of several antigens containing a broader range of protective epitopes that would cover a wide range of MHC types in a heterogeneous population. For practical considerations of vaccine development, we report on the generation of a single recombinant polyprotein comprising the sequences of all three open reading frames genetically linked in tandem. The resulting molecule, Leish-111f, comprises an open reading frame that codes for a 111kDa polypeptide. Evaluation of the immunogenicity and protective efficacy of Leish-111f formulated with IL-12 revealed that the immune responses to the individual components were maintained and as well, rLeish-111f protected BALB/c mice against L. major infection to a magnitude equal or superior to those seen with any of the individual components of the vaccine construct or SLA, a soluble Leishmania lysate. But because rIL-12 is expensive and difficult to manufacture and its efficacy and safety as an adjuvant for human use is questionable, we screened for other adjuvants that could potentially substitute for IL-12. We report that monophosphoryl lipid A (MPL) plus squalene (MPL-SE) formulated with rLeish-111f elicited protective immunity against L. major infection. The demonstrated feasibility to manufacture a single recombinant vaccine comprising multiple protective open reading frames and the potential use of MPL-SE as a substitute for IL-12, takes us closer to the realization of an affordable and safe Leishmania vaccine.
