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[show abstract]
[hide abstract]
ABSTRACT: Crotalus durissus terrificus venom and its main component, crotoxin (CTX), have the ability to down-modulate the immune system. Certain mechanisms mediated by cells and soluble factors of the immune system are responsible for the elimination of pathogenic molecules to ensure the specific protection against subsequent antigen contact. Accordingly, we evaluated the immunomodulatory effects of CTX on the immune response of mice that had been previously primed by immunisation with human serum albumin (HSA). CTX inoculation after HSA immunisation, along with complete Freund's adjuvant (CFA) or Aluminium hydroxide (Alum) immunisation, was able to suppress anti-HSA IgG1 and IgG2a antibody production. We showed that the inhibitory effects of this toxin are not mediated by necrosis or apoptosis of any lymphoid cell population. Lower proliferation of T lymphocytes from mice immunised with HSA/CFA or HSA/Alum that received the toxin was observed in comparison to the mice that were only immunised. In conclusion, CTX is able to exert potent inhibitory effects on humoral and cellular responses induced by HSA immunisation, even when injected after an innate immune response has been initiated.
Toxicon 01/2011; 57(4):600-7. · 2.51 Impact Factor
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I Fernandes,
G G Assumpção,
C R F Silveira, E L Faquim-Mauro,
I Tanjoni,
A K Carmona,
M F M Alves,
H A Takehara,
A Rucavado,
O H P Ramos,
A M Moura-da-Silva,
J M Gutiérrez
[show abstract]
[hide abstract]
ABSTRACT: BaP1 is a P-I class of Snake Venom Metalloproteinase (SVMP) relevant in the local tissue damage associated with envenomations by Bothrops asper, a medically-important species in Central America and parts of South America. Six monoclonal antibodies (MoAb) against BaP1 (MABaP1) were produced and characterized regarding their isotype, dissociation constant (K(d)), specificity and ability to neutralize BaP1-induced hemorrhagic and proteolytic activity. Two MABaP1 are IgM, three are IgG1 and one is IgG2b. The K(d)s of IgG MoAbs were in the nM range. All IgG MoAbs recognized conformational epitopes of BaP1 and B. asper venom components but failed to recognize venoms from 27 species of Viperidae, Colubridae and Elapidae families. Clone 7 cross-reacted with three P-I SVMPs tested (moojeni protease, insularinase and neuwiedase). BaP1-induced hemorrhage was totally neutralized by clones 3, 6 and 8 but not by clone 7. Inhibition of BaP1 enzymatic activity on a synthetic substrate by MABaP1 was totally achieved by clones 3 and 6, and partially by clone 8, but not by clone 7. In conclusion, these neutralizing MoAbs against BaP1 may become important tools to understand structure-function relationships of BaP1 and the role of P-I class SVMP in snakebite envenomation.
Toxicon 11/2010; 56(6):1059-65. · 2.51 Impact Factor
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[hide abstract]
ABSTRACT: Adult Ascaris suum body extract (Asc) prepared from male and female worms (with stored eggs) down-regulates the specific immune response of DBA/2 mice to ovalbumin (OA) and preferentially stimulates a Th2 response to its own components, which is responsible for the suppression of the OA-specific Th1 response. Here, we investigated the participation of soluble extracts prepared from male or female worms or from eggs (E-Asc) in these immunological events. Extracts from either sex (1 mg/animal) or E-Asc (0.35 or 1 mg protein/animal) suppressed the delayed-type hypersensitivity (DTH) reaction (60-85%), proliferative response (50-70%), IL-2 and IFN-gamma secretion (below detection threshold) and IgG1 antibody production (70-90%) of DBA/2 mice to OA. A dose of 0.1 mg E-Asc/animal did not change DTH or proliferation, but was as effective as 0.35 mg in suppressing IL-2 and IFN-gamma, and OA-specific IgG1 antibodies. Lymph node cells from DBA/2 mice injected with Asc (1 mg/animal) or a high dose of E-Asc (1 mg protein/animal) secreted IL-4 upon in vitro stimulation with concanavalin A. As previously demonstrated for Asc, the cytokine profile obtained with the E-Asc was dose dependent and changed towards Th1 when a low dose (0.1 mg protein/animal) was used. Taken together, these results suggest that adult worms of either sex and eggs induce the same type of T cell response and share similar immunosuppressive properties.
Brazilian Journal of Medical and Biological Research 02/2002; 35(1):81-9. · 1.13 Impact Factor
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[hide abstract]
ABSTRACT: Crotoxin (CTX) is a potent neurotoxin from Crotalus durissus terrificus snake venom (CdtV) composed of two subunits: one without catalytic activity (crotapotin), and a basic phospolipase A2. Recent data have demonstrated that CdtV or CTX inhibit some immune and inflammatory reactions.
The aim of this paper was to investigate the mechanisms involved in these impaired responses.
Male Swiss mice were bled before and at different intervals of time after subcutaneous injection of CTX or bovine serum albumin (BSA) (control animals). The effect of treatments on circulating leukocyte mobilisation and on serum levels of interleukin (IL)-6, IL-10, interferon (IFN)-gamma and corticosterone were investigated. Spleen cells from treated animals were also stimulated in vitro with concanavalin A to evaluate the profile of IL-4, IL-6, IL-10 or IFN-gamma secretion. Cytokine levels were determined by immunoenzymatic assay and corticosterone levels by radioimmunoassay. To investigate the participation of endogenous corticosteroid on the effects evoked by CTX, animals were treated with metyrapone, an inhibitor of glucocorticoid synthesis, previous to CTX treatment.
Marked alterations on peripheral leukocyte distribution, characterised by a drop in the number of lymphocytes and monocytes and an increase in the number of neutrophils, were observed after CTX injection. No such alteration was observed in BSA-treated animals. Increased levels of IL-6, IL-10 and corticosterone were also detected in CTX-injected animals. IFN-gamma levels were not modified after treatments. In contrast, spleen cells obtained from CTX-treated animals and stimulated with concanavalin A secreted less IL-10 and IL-4 in comparison with cells obtained from control animals. Metyrapone pretreatment was effective only to reverse the neutrophilia observed after CTX administration.
Our results suggest that CTX may contribute to the deficient inflammatory and immune responses induced by crude CdtV. CTX induces endogenous mechanisms that are responsible, at least in part, for these impaired responses.
Mediators of Inflammation 07/2001; 10(3):125-33. · 3.26 Impact Factor
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ABSTRACT: Adjuvants can modulate the levels of anaphylactic- and non-anaphylactic-type IgG1 antibodies produced in response to a particular antigen. Mice immunized with ovalbumin (OVA) in Al(OH)(3) gel (alum) produced mostly the anaphylactic type, irrespective of the s.c. or i.p. route used, and this antibody was not detectable in IL-4(-/-) mice. In contrast, when OVA was injected in complete Freund's adjuvant (CFA), it induced substantial amounts of non-anaphylactic-type IgG1 in both IL-4(+/+) and IL-4(-/-) mice, and some anaphylactic IgG1 antibody in IL-4(+/+) mice only. When IFN-gamma was neutralized by specific mAb in wild-type mice immunized with OVA in CFA, the anaphylactic-type IgG1 antibody increased reaching the same levels as in alum-injected mice. This result indicates that the induction of IFN-gamma by the immunization with CFA down-regulates the production of IL-4-dependent, anaphylactic-type IgG1. Despite their different effects on IgG1 antibody production, both adjuvants dramatically increased the production of IgG2a in IL-4-deprived mice and did not induce any detectable IgE in these mice.
International Immunology 01/2001; 12(12):1733-40. · 3.41 Impact Factor
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ABSTRACT: IL-4-dependent and -independent IgG1 Abs differ in their ability to induce mast cell degranulation as measured by passive cutaneous anaphylaxis (PCA). Mice immunized with OVA or PIII (fraction of Ascaris suum) produced high titers of IgG1 as shown by ELISA and PCA. In contrast, another A. suum fraction, PI, elicited IgG1 Abs with no PCA activity. IgG1 with anaphylactic activity required IL-4, as IgG1 responses to OVA and PIII in IL-4-/- mice gave no PCA. PI-specific IgG1 was IL-4-independent, because no difference was found between the responses of IL-4-/- and IL-4+/+ mice. Significant PCA reactions were elicited, however, with PI-specific IgG1 from IL-12-/- or anti-IFN-gamma Ab-treated mice, although less Ab was measured by ELISA. These results indicate that one type of IgG1 has anaphylactic activity and its synthesis is IL-4-dependent, being inhibited by IL-12 or IFN-gamma; the other lacks this activity and its synthesis is stimulated by IL-12 or IFN-gamma.
The Journal of Immunology 11/1999; 163(7):3572-6. · 5.79 Impact Factor
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ABSTRACT: The role of isolated components obtained by gel filtration chromatography of Ascaris suum body extract (Asc) on the modulation of the immune response to ovalbumin (OvA) was evaluated and correlated with the immunogenic properties of such components. We showed that high (PI), but not low (PIII), molecular weight components have the ability to inhibit OvA-induced immediate and DTH reactions, lymph node (LN) cell proliferation, cytokine (IL-2, interferon-gamma (IFN-gamma), IL-4 and IL-10) and antibody (IgG1, IgG2a, IgM and IgE) production in mice concomitantly immunized with OvA and these high mol. wt components. The pattern of cytokines synthesized in response to PI or PIII was totally different: the former induced more IL-4 and IL-10 and the latter more IL-2 and IFN-gamma. The levels of Asc-specific IgG1 antibodies were higher in mice immunized with OvA plus PI and IgG2a anti-Asc antibodies predominated in those immunized with PIII. IgE antibody production, however, was low in the former group of mice. These results indicate that the high mol. wt components present in the body extract from the helminth A. suum are responsible for its suppressive effect upon Th1- and Th2-dependent immune responses to an unrelated antigen. The suppression of the Th1-dependent parameters could be related to high-level expression of IL-4 and IL-10 induced by such components.
Clinical & Experimental Immunology 12/1998; 114(2):245-51. · 3.36 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Crotalus durissus terrificus venom and its main component, crotoxin (CTX), have the ability to down-modulate the immune system. Certain mechanisms mediated by cells and soluble factors of the immune system are responsible for the elimination of pathogenic molecules to ensure the specific protection against subsequent antigen contact. Accordingly, we evaluated the immunomodulatory effects of CTX on the immune response of mice that had been previously primed by immunisation with human serum albumin (HSA). CTX inoculation after HSA immunisation, along with complete Freund’s adjuvant (CFA) or Aluminium hydroxide (Alum) immunisation, was able to suppress anti-HSA IgG1 and IgG2a antibody production. We showed that the inhibitory effects of this toxin are not mediated by necrosis or apoptosis of any lymphoid cell population. Lower proliferation of T lymphocytes from mice immunised with HSA/CFA or HSA/Alum that received the toxin was observed in comparison to the mice that were only immunised. In conclusion, CTX is able to exert potent inhibitory effects on humoural and cellular responses induced by HSA immunisation, even when injected after an innate immune response has been initiated.
Toxicon.
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I. Fernandes,
G.G. Assumpção,
C.R.F. Silveira, E.L. Faquim-Mauro,
I. Tanjoni,
A.K. Carmona,
M.F.M. Alves,
H.A. Takehara,
A. Rucavado,
O.H.P. Ramos,
A.M. Moura-da-Silva,
J.M. Gutiérrez
[show abstract]
[hide abstract]
ABSTRACT: BaP1 is a P-I class of Snake Venom Metalloproteinase (SVMP) relevant in the local tissue damage associated with envenomations by Bothrops asper, a medically-important species in Central America and parts of South America. Six monoclonal antibodies (MoAb) against BaP1 (MABaP1) were produced and characterized regarding their isotype, dissociation constant (Kd), specificity and ability to neutralize BaP1-induced hemorrhagic and proteolytic activity. Two MABaP1 are IgM, three are IgG1 and one is IgG2b. The Kds of IgG MoAbs were in the nM range. All IgG MoAbs recognized conformational epitopes of BaP1 and B. asper venom components but failed to recognize venoms from 27 species of Viperidae, Colubridae and Elapidae families. Clone 7 cross-reacted with three P-I SVMPs tested (moojeni protease, insularinase and neuwiedase). BaP1-induced hemorrhage was totally neutralized by clones 3, 6 and 8 but not by clone 7. Inhibition of BaP1 enzymatic activity on a synthetic substrate by MABaP1 was totally achieved by clones 3 and 6, and partially by clone 8, but not by clone 7. In conclusion, these neutralizing MoAbs against BaP1 may become important tools to understand structure–function relationships of BaP1 and the role of P-I class SVMP in snakebite envenomation.
Toxicon.
