In vivo protective effect of the lectin from Canavalia brasiliensis on BALB/c mice infected by Leishmania amazonensis.
ABSTRACT In vivo administration of Canavalia brasiliensis lectin (at the time of infection, or maintained throughout the infection) reduced the lesions of highly susceptible BALB/c mice infected by Leishmania amazonensis. At the doses used C. brasiliensis lectin (ConBr) does not interfere with penetration or fate of Leishmania in the macrophages in vitro. Since Interferon-gamma (IFN-gamma) is the major macrophage activating factor, and considered a critical element in the successful immune response against leishmaniasis, we explored its participation in this phenomenon. ConBr either in vivo or in vitro induced IFN-gamma production in normal or in leishmania-infected BALB/c mice. However we were unable to change the course of disease by in vivo IFN-gamma administration (although IFN-gamma preparations were effective in inducing a leishmanicidal effect in vitro on L. amazonensis-infected peritoneal macrophages). Additionally, IFN-gamma neutralization with anti-IFN-gamma monoclonal antibody did not alter the protection conferred by ConBr administration. These data show that lectin administration in vivo is protective in the otherwise unchecked L. amazonensis infection of BALB/c mice, and suggest that such effect is not mediated by IFN-gamma.
Article: Partitioning and recovery of Canavalia brasiliensis lectin by aqueous two-phase systems using design of experiments methodology[show abstract] [hide abstract]
ABSTRACT: Separation and Purification Technology j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / s e p p u r Partitioning and recovery of Canavalia brasiliensis lectin by aqueous two-phase systems using design of experiments methodology: Canavalia brasilienses lectin Aqueous two-phase systems (ATPS) Design of experiments (DoE) Optimization Downstream processing a b s t r a c t The performance of aqueous two-phase systems (ATPS) composed by poly(ethylene glycol) (PEG)-and different salts (sodium citrate, potassium phosphate, sodium sulfate and ammonium sulfate) has been evaluated and compared for the selective isolation of Canavalia brasilienses lectin (ConBr) from crude extracts of C. brasilienses seeds. Among the systems studied, PEG-phosphate was the most efficient for the purification of ConBr. A central composite design was applied to study the effects of different factors such as, PEG concentration, phosphate buffer concentration, sodium chloride concentration and pH on ConBr extraction and to optimize its isolation from a plant extract. ATPS comprising PEG 600–phosphate buffer provided a means for the recovery of proteins from crude extracts of C. brasilienses seeds. The best conditions of purification were achieved using an ATPS composed by 16.5% (w/w) PEG 600, 15.0% (w/w) phosphate pH 7.5, 4.5% (w/w) NaCl. The maximum percentage yield of protein extracted was about 100% with a final purity of 73.04%.Separation and Purification Technology 01/2010; 75:48-54. · 2.92 Impact Factor
Article: CD4+ Th1 cells induced by dendritic cell-based immunotherapy in mice chronically infected with Leishmania amazonensis do not promote healing.[show abstract] [hide abstract]
ABSTRACT: The susceptibility of mice to Leishmania amazonensis infection is thought to result from an inability to develop a Th1 response. Our data show that the low levels of gamma interferon (IFN-gamma) produced by the draining lymph node (DLN) cells of chronically infected mice could be enhanced in vitro and in vivo with L. amazonensis antigen-pulsed bone marrow-derived dendritic cells (BM-DC) and the Th1-promoting cytokine interleukin-12 (IL-12). Given intralesionally to chronically infected mice, this treatment induced the upregulation of mRNA levels for IFN-gamma, the transcription factor T-box expressed in T cells, and IL-12 receptor beta 2 in CD4(+) T cells from the DLN and an increase in parasite-specific immunoglobulin G2a in the serum. However, this Th1 response was not associated with healing, and the antigen-specific enhancement of IFN-gamma production remained impaired in the DLN. However, addition of IL-12 to the in vitro recall response was able to recover this defect, suggesting that antigen-presenting cell-derived IL-12 production may be limited in infected mice. This was supported by the fact that L. amazonensis amastigotes limited the production of IL-12p40 from BM-DC in vitro. Altogether, our data indicate that the immune response of mice chronically infected with L. amazonensis can be enhanced towards a Th1 phenotype but that the presence of Th1 CD4(+) T cells does not promote healing. This suggests that the phenotype of the CD4(+) T cells may not always be indicative of protection to L. amazonensis infection. Furthermore, our data support growing evidence that antigen-presenting cell function, such as IL-12 production, may limit the immune response in L. amazonensis-infected mice.Infection and Immunity 09/2004; 72(8):4455-63. · 4.16 Impact Factor
Article: Impaired expression of inflammatory cytokines and chemokines at early stages of infection with Leishmania amazonensis.[show abstract] [hide abstract]
ABSTRACT: Infection of mice with Leishmania major results in disease progression or resolution, largely depending on the genetic backgrounds of the mouse strains. Infection with Leishmania amazonensis, on the other hand, causes progressive cutaneous lesions in most inbred strains of mice. We hypothesized that deficient activation of early immune responses contributes to the pathogenesis in L. amazonensis-infected mice. To distinguish early molecular events that determine the outcome of Leishmania infections, we examined cytokine gene expression in C57BL/6 mice infected with either L. amazonensis or L. major (a healing model). After 2 to 4 weeks, L. amazonensis-infected mice had significantly delayed and depressed expression of inflammatory cytokines (interleukin-12 [IL-12], gamma interferon, IL-1 alpha, IL-1 beta), CC chemokines (CC chemokine ligand 3 [CCL3]/macrophage inflammatory protein 1 alpha [MIP-1 alpha], CCL4/MIP-1 beta, CCL5/RANTES, MIP-2), and chemokine receptors (CCR1, CCR2, CCR5) in foot tissues and draining lymph nodes compared to the expression in L. major-infected controls. These findings correlated with defective T-cell responsiveness to parasite stimulation in vivo and in vitro. Adoptive transfer of L. amazonensis-specific Th1 cells prior to infection overcame the immune defects of the animals, leading to complete control of the disease. Studies with gene knockout mice suggested that IL-10, but not IL-4, contributed partially to compromised immunity in L. amazonensis-infected hosts. The data suggest that there is impairment in multiple immune functions at early stages of infection with L. amazonensis parasites and provide a compelling rationale to explore immune augmentation as an intervention in American cutaneous leishmaniasis.Infection and Immunity 09/2003; 71(8):4278-88. · 4.16 Impact Factor