Maternal immunization with ovalbumin prevents neonatal allergy development and up-regulates inhibitory receptor Fc gamma RIIB expression on B cells

Background: Preconception allergen immunization prevents neonatal allergen sensitization in mice by a complex interaction between regulatory cells/factors and antibodies. The present study assessed the influence of maternal immunization with ovalbumin (OVA) on the immune response of 3 day-old and 3 week-old offspring immunized or non-immunized with OVA and evaluated the effect of IgG treatment during fetal development or neonatal period. Results: Maternal immunization with OVA showed increased levels of Fc gamma RIIb expression in splenic B cells of neonates, which were maintained for up to 3 weeks and not affected by additional postnatal OVA immunization. Maternal immunization also exerted a down-modulatory effect on both IL-4 and IFN-gamma-secreting T cells and IL-4 and IL-12-secreting B cells. Furthermore, immunized neonates from immunized mothers showed a marked inhibition of antigen-specifc IgE Ab production and lowered Th2/Th1 cytokine levels, whereas displaying enhanced Fc gamma RIIb expression on B cells. These offspring also showed reduced antigen-specific proliferative response and lowered B cell responsiveness. Moreover, in vitro evaluation revealed an impairment of B cell activation upon engagement of B cell antigen receptor by IgG from OVA-immunized mice. Finally, in vivo IgG transference during pregnancy or breastfeeding revealed that maternal Ab transference was able to increase regulatory cytokines, such as IL-10, in the prenatal stage; yet only the postnatal treatment prevented neonatal sensitization. None of the IgG treatments induced immunological changes in the offspring, as it was observed for those from OVA-immunized mothers. Conclusion: Maternal immunization upregulates the inhibitory Fc gamma RIIb expression on offspring B cells, avoiding skewed Th2 response and development of allergy. These findings contribute to the advancement of prophylactic strategies to prevent allergic diseases in early life.

Immunological Basis for the Gender Differences in Murine Paracoccidioides brasiliensis Infection

This study aimed to investigate the immunological mechanisms involved in the gender distinct incidence of paracoccidioidomycosis (pcm), an endemic systemic mycosis in Latin America, which is at least 10 times more frequent in men than in women. Then, we compared the immune response of male and female mice to Paracoccidioides brasiliensis infection, as well as the influence in the gender differences exerted by paracoccin, a P. brasiliensis component with carbohydrate recognition property. High production of Th1 cytokines and T-bet expression have been detected in the paracoccin stimulated cultures of spleen cells from infected female mice. In contrast, in similar experimental conditions, cells from infected males produced higher levels of the Th2 cytokines and expressed GATA-3. Macrophages from male and female mice when stimulated with paracoccin displayed similar phagocytic capability, while fungicidal activity was two times more efficiently performed by macrophages from female mice, a fact that was associated with 50% higher levels of nitric oxide production. In order to evaluate the role of sexual hormones in the observed gender distinction, we have utilized mice that have been submitted to gonadectomy followed by inverse hormonal reconstitution. Spleen cells derived from castrated males reconstituted with estradiol have produced higher levels of IFN-gamma (1291+/-15 pg/mL) and lower levels of IL-10 (494+/-38 pg/mL), than normal male in response to paracoccin stimulus. In contrast, spleen cells from castrated female mice that had been treated with testosterone produced more IL-10 (1284+/-36 pg/mL) and less IFN-gamma (587614 pg/mL) than cells from normal female. In conclusion, our results reveal that the sexual hormones had a profound effect on the biology of immune cells, and estradiol favours protective responses to P. brasiliensis infection. In addition, fungal components, such as paracoccin, may provide additional support to the gender dimorphic immunity that marks P. brasiliensis infection.

The Spleen CD4(+) T Cell Response to Blood-Stage Plasmodium chabaudi Malaria Develops in Two Phases Characterized by Different Properties

The pivotal role of spleen CD4(+) T cells in the development of both malaria pathogenesis and protective immunity makes necessary a profound comprehension of the mechanisms involved in their activation and regulation during Plasmodium infection. Herein, we examined in detail the behaviour of non-conventional and conventional splenic CD4(+) T cells during P. chabaudi malaria. We took advantage of the fact that a great proportion of CD4(+) T cells generated in CD1d(-/-) mice are I-A(b)-restricted (conventional cells), while their counterparts in I-Ab(-/-) mice are restricted by CD1d and other class IB major histocompatibility complex (MHC) molecules (non-conventional cells). We found that conventional CD4(+) T cells are the main protagonists of the immune response to infection, which develops in two consecutive phases concomitant with acute and chronic parasitaemias. The early phase of the conventional CD4(+) T cell response is intense and short lasting, rapidly providing large amounts of proinflammatory cytokines and helping follicular and marginal zone B cells to secrete polyclonal immunoglobulin. Both TNF-alpha and IFN-gamma production depend mostly on conventional CD4(+) T cells. IFN-gamma is produced simultaneously by non-conventional and conventional CD4(+) T cells. The early phase of the response finishes after a week of infection, with the elimination of a large proportion of CD4(+) T cells, which then gives opportunity to the development of acquired immunity. Unexpectedly, the major contribution of CD1d-restricted CD4(+) T cells occurs at the beginning of the second phase of the response, but not earlier, helping both IFN-gamma and parasite-specific antibody production. We concluded that conventional CD4(+) T cells have a central role from the onset of P. chabaudi malaria, acting in parallel with non-conventional CD4(+) T cells as a link between innate and acquired immunity. This study contributes to the understanding of malaria immunology and opens a perspective for future studies designed to decipher the molecular mechanisms behind immune responses to Plasmodium infection.

Administration of Mycobacterium leprae rHsp65 Aggravates Experimental Autoimmune Uveitis in Mice

The 60kDa heat shock protein family, Hsp60, constitutes an abundant and highly conserved class of molecules that are highly expressed in chronic-inflammatory and autoimmune processes. Experimental autoimmune uveitis [EAU] is a T cell mediated intraocular inflammatory disease that resembles human uveitis. Mycobacterial and homologous Hsp60 peptides induces uveitis in rats, however their participation in aggravating the disease is poorly known. We here evaluate the effects of the Mycobacterium leprae Hsp65 in the development/progression of EAU and the autoimmune response against the eye through the induction of the endogenous disequilibrium by enhancing the entropy of the immunobiological system with the addition of homologous Hsp. B10. RIII mice were immunized subcutaneously with interphotoreceptor retinoid-binding protein [IRBP], followed by intraperitoneally inoculation of M. leprae recombinant Hsp65 [rHsp65]. We evaluated the proliferative response, cytokine production and the percentage of CD4(+)IL-17(+), CD4(+)IFN-gamma(+) and CD4(+)Foxp3(+) cells ex vivo, by flow cytometry. Disease severity was determined by eye histological examination and serum levels of anti-IRBP and anti-Hsp60/65 measured by ELISA. EAU scores increased in the Hsp65 group and were associated with an expansion of CD4(+)IFN-gamma(+) and CD4(+)IL-17(+) T cells, corroborating with higher levels of IFN-gamma. Our data indicate that rHsp65 is one of the managers with a significant impact over the immune response during autoimmunity, skewing it to a pathogenic state, promoting both Th1 and Th17 commitment. It seems comprehensible that the specificity and primary function of Hsp60 molecules can be considered as a potential pathogenic factor acting as a whistleblower announcing chronic-inflammatory diseases progression.

Salivary immunoglobulin a response to a match in top-level Brazilian soccer players

Moreira, A, Arsati, F, Cury, PR, Franciscon, C, Oliveira, PR, and Araujo, VC. Salivary immunoglobulin a response to a match in top-level brazilian soccer players. J Strength Cond Res 23(7): 1968-1973, 2009-It has been suggested that several parameters of mucosal immunity, including salivary immunoglobulin A (s-IgA), are affected by heavy exercise either in field sports or in the laboratory environment. Few observations have been made during a true sporting environment, particularly in professional soccer. We tested the hypothesis that salivary IgA levels will be decreased after a 70-minute regulation in a top-level professional soccer friendly match. Saliva samples from 24 male professional soccer players collected before and after the match were analyzed. Salivary immunoglobulin A concentration was measured by enzyme-linked immunosorbent assay and expressed as the absolute concentration (s-IgAabs), s-IgA relative to total protein concentration (IgA-Pro), and the secretion rate of IgA (s-IgArate). Rate of perceived exertion (RPE) was used to monitor the exercise intensity. The paired t-test showed no significant changes in s-IgAabs and s-IgArate (p > 0.05) from PRE to POST match. However, a significant (p < 0.05) increase in total protein concentration (1.46 +/- 0.4 to 2.00 +/- 07) and a decrease in IgA-Pro were observed. The best and most significant correlation was obtained with the RPE and changes in IgA-Pro (rs = -0.43) and could indicate that this expression may be an interesting marker of intensity in a soccer match. However, further investigation regarding exercise intensity, protein concentration, and immune suppression, particularly in team sports, is warranted. From a practical application, the variability of the responses among the players leads us to suggest that there is a need to individually analyze the results with team sports. Some athletes showed a decrease in s-IgA expressions, suggesting the need for taking protective actions to minimize contact with cold viruses or even reducing the training load.

Immunology of Dermatophytosis

The immune response to infection by dermatophytes ranges from a non-specific host mechanism to a humoral and cell-mediated immune response. The currently accepted view is that a cell-mediated immune response is responsible for the control of dermatophytosis. Indeed, some individuals develop a chronic or recurrent infection mediated by the suppression of a cell-mediated immune response. The immune response to Trichophyton is unusual in that this fungus can elicit both immediate hypersensitivity (IH) and delayed-type hypersensitivity (DTH) in different individuals when they are submitted to a skin test reaction. Understanding the nature and function of the immune response to dermatophytes is an exciting challenge that might lead to novel approaches in the treatment and immunological prophylaxis of dermatophytosis.

Protein-Energy Malnutrition Modifies the Production of Interleukin-10 in Response to Lipopolysaccharide (LPS) in a Murine Model

Malnutrition modifies resistance to infection by impairing a number of physiological processes including hematopoesis and the immune response. In this study, we examined the production of Interleukin-4 (IL-4) and IL-10 in response to lipopolysaccharide (LPS) and also evaluated the cellularity of the blood, bone marrow, and spleen in a mouse model of protein-energy malnutrition. Two-month-old male Swiss mice were subjected to protein-energy malnutrition (PEM) with a low-protein diet (4%) as compared to the control diet (20%). When the experimental group lost approximately 20% of their original body weight, the animals from both groups received 1.25 mu g of LPS intravenously. The Cells ill the blood, bone marrow, and spleen were counted, and circulating levels of IL-4 and IL-10 were evaluated in animals stimulated with LPS. Cells from the spleen, bone marrow, and peritoneal cavity of non-inoculated animals were collected for Culture to evaluate the production of IL-4 and IL-10 after stimulating these cells with 1.25 mu g of LPS in vitro. Malnourished animals presented leucopenia and a severe reduction in bone marrow, spleen, and peritoneal cavity cellularity before and after Stimulus with LPS. The circulating levels of IL-10 were increased in malnourished animals inoculated with LPS when compared to control animals, although the levels of IL-4 did not differ. In cells cultured with LPS, we observed high levels of IL-10 in the bone marrow cells of malnourished animals. These findings suggest that malnourished mice present a deficient immune response to LPS. These alterations may be partly responsible for the immunodeficiency observed in these malnourished mice.

Tityus serrulatus venom and toxins Ts1, Ts2 and Ts6 induce macrophage activation and production of immune mediators

Scorpion envenomation induces a systemic immune response, and neurotoxins of venom act on specific ion channels, modulating neurotransmitter release or activity. However, little is known about the immunomodulatory effects of crude venom from scorpion Tityus serrulatus (TsV) or its toxins (Ts1, Ts2 and Ts6) in combination with lipopolysaccharide (LPS). To investigate the immunomodulatory effects of TsV and its toxins (Ts1, Ts2 and Ts6), J774.1 cells were stimulated with different concentrations (25, 50 and 100 mu g/mL) of venom or toxins pre-stimulated or not with LPS (0.5 mu g/mL). Macrophage cytotoxicity was assessed, and nitric oxide (NO) and cytokine production were analyzed utilizing the culture supernatants. TsV and its toxins did not produce cytotoxic effects. Depending on the concentrations used, TsV, Ts1 and Ts6 stimulated the production of NO, interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha in J774.1 cells, which were enhanced under LPS co-stimulation. However, LPS + Ts2 inhibited NO, IL-6 and TNF-alpha production, and Ts2 alone stimulated the production of IL-10, suggesting an anti-inflammatory activity for this toxin. Our findings are important for the basic understanding of the mechanisms involved in macrophage activation following envenomation: additionally, these findings may contribute to the discovery of new therapeutic compounds to treat immune-mediated diseases. (C) 2011 Elsevier Ltd. All rights reserved.

DNAhsp65 vaccination induces protection in mice against Paracoccidioides brasiliensis infection

Heat-shock proteins are Molecules with extensive data showing their potential as immunomodulators of different types of diseases, The gene of HSP65 from Mycobacterium leprae has shown prophylactic and immunotherapeutic effects against a broad arrays of experimental models including tuberculosis, leishmaniasis, arthritis and diabetes. With this in mind, we tested the DNAhsp65 vaccine using an experimental model of Paraccocidiodomycosis, an important endemic mycosis in Latin America. The intramuscular immunization with DNAhsp65 induced, in BALB/c mice, an increase of Th1-levels cytokines and a reduction of fungal burdens resulted in a marked reduction of collagen and lung remodeling. DNAhsp65 may be an attractive candidate for prevention, therapy and as an adjuvant for mycosis treatment. (C) 2008 Elsevier Ltd. All rights reserved.

Leukotrienes Are Potent Adjuvant during Fungal Infection: Effects on Memory T Cells

Leukotrienes (LTs) are potent lipid mediators involved in the control of host defense. LTB(4) induces leukocyte accumulation, enhances phagocytosis and bacterial clearance, and increases NO synthesis. LTB(4) is also important in early effector T cell recruitment that is mediated by LTB(4) receptor 1, the high-affinity receptor for LTB(4). The aims of this study were to evaluate whether LTs are involved in the secondary immune response to vaccination in a murine model of Histoplasma capsulatum infection. Our results demonstrate that protection of wild-type mice immunized with cell-free Ags from H. capsulatum against histoplasmosis was associated with increased LTB(4) and IFN-gamma production as well as recruitment of memory T cells into the lungs. In contrast, cell-free Ag-immunized mice lacking 5-lipoxygenase(-/-), a critical enzyme involved in LT synthesis, displayed a marked decrease on recruitment of memory T cells to the lungs associated with increased synthesis of TGF-beta as well as IL-10. Strikingly, these effects were associated with increased mortality to 5-lipoxygenase(-/-)-infected mice. These data establish an important immunomodulatory role of LTs, in both the primary and secondary immune responses to histoplasmosis. The Journal of Immunology, 2008,181: 8544-8551.

Prostaglandin E(2)-loaded microspheres as strategy to inhibit phagocytosis and modulate inflammatory mediators release

PGE(2), an arachidonic acid metabolite produced by various type of cells regulates a broad range of physiological activities in the endocrine, cardiovascular, gastrointestinal, and immune systems, and is involved in maintaining the local homeostasis. In the immune system, PGE(2) is mainly produced by APCs and it can suppress the Th1-mediated immune responses. The aim of this study was to develop PGE(2)-loaded biodegradable MS that prolong and sustain the in vivo release of this mediator. An o/w emulsion solvent extraction-evaporation method was chosen to prepare the MS. We determined their diameters, evaluated the in vitro release of PGE(2), using enzyme immunoassay and MS uptake by peritoneal macrophages. To assess the preservation of biological activities of this mediator, we determined the effect of PGE(2) released from MS on LPS-induced TNF-alpha release by murine peritoneal macrophages. We also analyzed the effect of encapsulated PGE(2) on inflammatory mediators release from HUVECs. Finally, we studied the effect of PGE(2) released from biodegradable MS in sepsis animal model. The use of this formulation can provide an alternative strategy for treating infections, by modulating or inhibiting inflammatory responses, especially when they constitute an exacerbated profile. (C) 2008 Elsevier B.V. All rights reserved.

Melatonin enhances pro-inflammatory cytokine levels and protects against Chagas disease

Pro-inflammatory and modulatory cytokines have an essential role in host defense against human and murine Trypanosoma cruzi infection. Control of T. cruzi parasitism during the acute phase of infection is considered to be critically dependent on direct macrophage activation by cytokines. Melatonin has been proposed to regulate the immune system by affecting cytokine production in immunocompetent cells, enhancing the production of several T helper (Th)1 cytokines. The aims of this work were to evaluate in rats, the influences of exogenous melatonin treatment on T. cruzi-infected host`s immune responses. With this in mind, several immunological parameters were analyzed, including tumor necrosis factor-alpha, gamma-interferon, interleukin-12, nitric oxide (NO) and macrophage count. The melatonin therapy was provided in one of two different treatment regimens, that is, either beginning 7 days prior to infection or concomitant with the infection. Both treatments triggered an up-regulation of the immune response, with the concomitant treatment being more effective; in this case all cytokines studied, with exception of NO, displayed enhanced concentrations and there was a higher number of peritoneal macrophages, which displayed reduced concentrations under melatonin therapy. We conclude that melatonin plays a pivotal role in up-regulating the Th1 immune response thus controlling parasite replication.

Enhanced protection by melatonin and meloxicam combination in experimental infection by Trypanosoma cruzi

P>The aim of this study was to evaluate a possible synergism between melatonin and meloxicam in up-regulating the immune response in male Wistar rats infected with Trypanosoma cruzi during immunosuppression phenomenon, which characterizes the acute phase of the Chagas` disease. Male Wistar rats were infected with the Y strain of T. cruzi. Experiments were performed on 7, 14 and 21 days post-infection. Several immunological parameters were evaluated including gamma-interferon (IFN-gamma), interleukin-2 (IL-2), nitric oxide (NO) and prostaglandin E(2) (PGE(2)). The combined treatment with melatonin and meloxicam significantly enhanced the release of IL-2 and INF-gamma into animals` serum, when compared with the infected control groups during the course of infection. Furthermore, the blockade of PGE(2) synthesis and the increased release of NO by macrophage cells from T. cruzi-infected animals contributed to regulate the production of Th1 subset cytokines significantly reducing the parasitaemia in animals treated with the combination of both substances. Therefore, our results suggest that the association of melatonin and meloxicam was more effective in protecting animals against the harmful actions of T. cruzi infection as compared with the treatments of meloxicam or melatonin alone.

Trypanosoma cruzi: Do different sylvatic strains trigger distinct immune responses?

Strains of Trypanosoma cruzi are multiclonal populations that can be classified in groups or genotypes, differing in pathogenicity, virulence, and histotropism. In this experiment the distinct behavior of two strains of T. cruzi, MORC-1 and MORC-2, was documented. Blood parasitemia, spleen proliferation, nitric oxide, histopathology of the spleen and heart were used as tools to evaluate parasite persistence. Groups of male mice were separated and divided in three groups: Control (C), Infected (IM-1) and Infected (IM-2). The peak of parasitemia occurred on 10 days post infection for both strains. LPS stimulated animals, infected MORC-2 group displayed significant higher concentrations of NO when compared to infected MORC-1 group (P < 0.05). For ConA stimulated lymphoproliferation, infected MORC-1 group displayed higher proliferation index as compared to infected MORC-2 group. An opposite behavior for IL-4 and TNF-alpha was observed according to the strain. For MORC-1 enhanced concentrations of IL-4 were present with concomitant reduced levels of TNF-alpha, while for MORC-2 enhanced concentrations of TNF-alpha and reduced levels of IL-4 were found. The histopathology of heart and spleen showed important differences in which MORC-1 displayed statistically enhanced number of amastigote in the heart and spleen as compared to MORC-2. Concluding, each strain triggered a distinct immune response with enhanced cytokine TH-1 profile for MORC-2 and TH-2 for MORC-1. (C) 2009 Elsevier Inc. All rights reserved.

TLR2-dependent mast cell activation contributes to the control of Mycobacterium tuberculosis infection

Mast Cells (MCs) express toll-like receptor 2 (TLR2), a receptor known to be triggered by several major mycobacterial ligands and involved in resistance against Mycobacterium tuberculosis (MTB) infection. This study investigated whether adoptive transfer of TLR2 positive MCs (TLR2(+/+)) corrects the increased susceptibility of TLR2(-/-) mice to MTB infection. TLR2(-/-) mice displayed increased mycobacterial burden, diminished myeloid cell recruitment and proinflammatory cytokine production accompanied by defective granuloma formation. The reconstitution of these mice with TLR2(+/+) MCs, but not TLR2(-/-), confers better control of the infection, promotes the normalization of myeloid cell recruitment associated with reestablishment of the granuloma formation. In addition, adoptive transfer of TLR2(+/+) MC to TLR2(-/-) mice resulted in regulation of the pulmonary levels of IL-beta, IL-6, TNF-alpha, enhanced Th1 response and activated CD8(+) T cell homing to the lungs. Our results suggest that activation of MCs via TLR2 is required to compensate the defect in protective immunity and inability of TLR2(-/-) mice to control MTB infection. (C) 2009 Elsevier Masson SAS. All rights reserved.