Peptides containing T cell epitopes, derived from Sm14, but not from paramyosin, induce a Th1 type of immune response, reduction in liver pathology and partial protection against Schistosoma mansoni infection in mice

Sm14 and paramyosin are two major Schistosoma mansoni vaccine candidate antigens. Recently, we have identified Sm14 and paramyosin epitopes that are recognized by T cells of resistant individuals living in endemic areas for schistosomiasis. Herein, mice were immunized with these peptides separately or in association in order to evaluate their vaccine potential. Immunization of mice with Sm14 peptides alone or mixed with paramyosin peptides was able to induce 26%-36.7% or 28%-29.2% of worm burden reduction, 67% or 46% of intestinal eggs reduction and also 54%-61% or 43%-52% of liver pathology reduction, respectively. Protection was associated with a Th1 type of immune response induced by Sm14 peptide immunization. In contrast, paramyosin peptide vaccination did not engender protective immunity or liver pathology reduction and immunization was associated with a Th2 type of immune response. (C) 2008 Elsevier B.V. All rights reserved.

Lack of galectin-3 alters the balance of innate immune cytokines and confers resistance to Rhodococcus equi infection

Galectin-3 is a p-galactoside-binding lectin implicated in the fine-tuning of innate immunity. Rhodococcus equi, a facultative intracellular bacterium of macrophages, causes severe granulomatous bronchopneumonia in young horses and immunocompromised humans. The aim of this study is to investigate the role of galectin-3 in the innate resistance mechanism against R. equi infection. The bacterial challenge of galectin-3-deficient mice (gal3(-/-)) and their wild-type counterpart (gal3(+/+)) revealed that the LD50 for the gal3(-/-) mice was about seven times higher than that for the gal3(+/+) mice. When challenged with a sublethal dose, gal3(-/-) mice showed lower bacteria counts and higher production of IL-12 and IFN-gamma production, besides exhibiting a delayed although increased inflammatory reaction. Gal3(-/-) macrophages exhibited a decreased frequency of bacterial replication and survival, and higher transcript levels of IL-1 beta, IL-6, IL-10, TLR2 and MyD88. R. equi-infected gal3(+/+) macrophages showed decreased expression of TLR2, whereas R. equi-infected gal3(-/-) macrophages showed enhanced expression of this receptor. Furthermore, galectin-3 deficiency in macrophages may be responsible for the higher IL-1 beta serum levels detected in infected gal3(-/-) mice. Therefore galectin-3 may exert a regulatory role in innate immunity by diminishing IL-1 beta production and thus affecting resistance to R. equi infection.

Decrease in Mycobacterium tuberculosis specific immune responses in patients with untreated psoriasis living in a tuberculosis endemic area

Tuberculosis has emerged as a major concern in patients with immuno-mediated diseases, including psoriasis, undergoing treatment with biologicals. However, it is not known whether the chronically activated immune system of psoriasis patients interferes with their Mycobacterium tuberculosis (Mtb)-specific immunity, especially in tuberculosis-endemic areas like Brazil. We evaluated T-cell responses to a Mtb lysate and to the recombinant Mtb proteins ESAT-6 and Ag85B of tuberculin skin test (TST) positive and TST negative patients with severe or mild/moderate, untreated psoriasis in three different assays: lymphocyte proliferation, enzyme immunoassay for interferon (IFN)-gamma and interleukin (IL)-10 production by peripheral blood mononuclear cells and overnight enzyme immunospot (ELISpot) for enumerating IFN-gamma-secreting cells. In our cohort, a low proportion (29%) of the severe psoriasis patients tested were TST-positive. IFN-gamma and IL-10 secretion and T-cell proliferation to Mtb antigens were reduced in TST-negative but not in TST-positive patients with severe psoriasis when compared to healthy controls with the same TST status. Similarly, severe psoriasis patients had decreased cytokine secretion and proliferative response to phytohemagglutinin. However, most psoriasis patients and healthy controls showed detectable numbers of IFN-gamma-secreting effector-memory T-cells in response to Mtb antigens by ELISpot. TST-negative, mild/moderate psoriasis patients had responses that were mostly intermediary between TST-negative controls and severe psoriasis patients. Thus, patients with severe psoriasis possess decreased anti-Mtb central memory T-cell responses, which may lead to false-negative results in the diagnosis of TB infection, but retain T-cell memory-effector activity against Mtb antigens. We hypothesize that the latter may confer some protection against tuberculosis reactivation.

In situ apoptosis of adaptive immune cells and the cellular escape of rabies virus in CNS from patients with human rabies transmitted by Desmodus rotundus

The aim of the current study was to investigate the apoptosis of neurons, astrocytes and immune cells from human patients that were infected with rabies virus by vampire bats bite. Apoptotic neurons were identified by their morphology and immune cells were identified using double immunostaining. There were very few apoptotic neurons present in infected tissue samples, but there was an increase of apoptotic infiltrating CD4+ and TCD8+ adaptive immune cells in the rabies infected tissue. No apoptosis was present in NK, macrophage and astrocytes. The dissemination of the human rabies virus within an infected host may be mediated by viral escape of the virus from an infected cell and may involve an anti-apoptotic mechanism, which does not kill the neuron or pro-apoptosis of TCD4+ and TCD8+ lymphocytes and which allows for increased proliferation of the virus within the CNS by attenuation of the adaptive immune response. (C) 2011 Elsevier B.V. All rights reserved.

Immunization of neonatal mice with LAMP/p55 HIV gag DNA elicits robust immune responses that last to adulthood

Successful T cell priming in early postnatal life that can generate effective long-lasting responses until adulthood is critical in HIV vaccination strategies because it prevents early sexual initiation and breastfeeding transmission of HIV. A chimeric DNA vaccine encoding p55 HIV gag associated with lysosome-associated membrane protein 1 (LAMP-1; which drives the antigen to the MIIC compartment), has been used to enhance cellular and humoral antigen-specific responses in adult mice and macaques. Herein, we investigated LAMP-1/gag vaccine immunogenicity in the neonatal period in mice and its ability to generate long-lasting effects. Neonatal vaccination with chimeric LAMP/gag generated stronger Gag-specific immune responses, as measured by the breadth of the Gag peptide-specific IFN-gamma, proliferative responsiveness, cytokine production and antibody production, all of which revealed activation of CD4+ T cells as well as the generation of a more robust CTL response compared to gag vaccine alone. To induce long-lived T and B cell memory responses, it was necessary to immunize neonates with the chimeric IAMP/gag DNA vaccine. The LAMP/gag DNA vaccine strategy could be particularly useful for generating an anti-HIV immune response in the early postnatal period capable of inducing long-term immunological memory. (C) 2010 Elsevier Inc. All rights reserved.

Humoral responses and immune protection in mice immunized with irradiated T. gondii tachyzoites and challenged with three genetically distinct strains of T. gondii

Toxoplasma gondii is an obligate intracellular parasite that infects a variety of mammals and birds. T. gondii also causes human toxoplasmosis; although toxoplasmosis is generally a benign disease, ocular, congenital or reactivated disease is associated with high numbers of disabled people. Infection occurs orally through the ingestion of meat containing cysts or by the intake of food or water contaminated with oocysts. Although the immune system responds to acute infection and mediates the clearance of tachyzoites, parasite cysts persist for the lifetime of the host in tissues such as the eye, muscle, and CNS. However, T. gondii RH strain tachyzoites irradiated with 255 Gy do not cause residual infection and induce the same immunity as a natural infection. To assess the humoral response in BALB/c and C57BL/6J mice immunized with irradiated tachyzoites either by oral gavage (p.o.) or intraperitoneal (i.p.) injection, we analyzed total and high-affinity IgG and IgA antibodies in the serum. High levels of antigen-specific IgG were detected in the serum of parenterally immunized mice, with lower levels in mice immunized via the oral route. However, most serum antibodies exhibited low affinity for antigen in both mice strain. We also found antigen specific IgA antibodies in the stools of the mice, especially in orally immunized BALB/c mice. Examination of bone marrow and spleen cells demonstrated that both groups of immunized mice clearly produced specific lgG, at levels comparable to chronic infection, suggesting the generation of IgG specific memory. Next, we challenged i.p. or p.o. immunized mice with cysts from ME49. VEG or P strains of T. gondii. Oral immunization resulted in partial protection as compared to challenged naive mice: these findings were more evident in highly pathogenic ME49 strain challenge. Additionally, we found that while mucosal IgA was important for protection against infection, antigen-specific IgG antibodies were involved with protection against disease and disease pathogenesis. Most antigen responsive cells in culture produced specific high-affinity IgG after immunization, diverse of the findings in serum IgG or from cells after infection, which produced low proportion of high-avidity IgG. (C) 2011 Elsevier B.V. All rights reserved.

Histopathology, humoral and cellular immune response in the murine model of Leishmania (Viannia) shawi

Leishmania (Viannia) shawl was recently characterized and few studies concerning modifications in cellular and humoral immune responses in experimental leishmaniasis have been conducted. In this work, immunopathological changes induced by L. shawl in chronically infected BALB/c mice were investigated. Infected BALB/c mice developed increased lesion size associated with strong inflammatory infiltrate diffusely distributed in the dermis, with highly infected macrophages. The humoral immune response was predominantly directed toward the IgG1 isotype. The functional activity of CD4(+) and CD8(+) T cells showed significantly increased TNF-alpha mRNA levels associated with reduced IFN-gamma expression by CD4(+) T cells and the double negative (dn) CD4CD8 cell subset. High IL-4 levels expressed by CD8(+) T cells and dnCD4CD8 and TGF-beta by CD4(+) and CD8(+) T cells were detected, while IL-10 was highly expressed by all three cell subpopulations. Taken together, these results show an evident imbalance between TNF-alpha and IFN-gamma that is unfavorable to amastigote replication control. Furthermore, L. shawi seems to regulate different cell populations to express deactivating cytokines to avoid its own destruction. This study indicates BALB/c mice as a potentially good experimental model for further studies on American cutaneous leishmaniosis caused by L. shawi. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Characterization of cytotoxic immune response in skin and mucosal lesions of paracoccidioidomycosis

Background: CD8+ T cells and natural killer (NK) cells are involved in the immune response against some pathogens. For this purpose, we investigated the in situ paracoccidioidomycosis (PCM) immune response addressing the participation of NK cells, CD8+ T cells, perforin and granzyme B expression. Methods: Sixty biopsies of PCM skin and mucosa were classified according to the presence of compact granulomas (G1), poorly organized granulomas (G2) and both kinds in the same lesion (G3). CD8+ T cells, NK cells, perforin and granzyme B were showed by immunohistochemistry. Results: CD8+ T cells were increased over NK cells in cutaneous G1 and G2 lesions. There was no difference regarding such cells in G3 lesions, although they were abundant in such lesions. In mucosa, CD8+ T cells were increased in number over NK cells in all groups. Granzyme B in skin increased in G2 and G3. The number of granzyme did not differ in mucosal lesions in the three groups. Conclusions: CD8+ T cells and NK cells play a role in PCM cutaneous and mucosal lesions. The predominance of CD8+ T cells over NK cells may represent an effective response against the fungi. Moreover, the high number of granzyme B expressing cells corroborates this possibility.

Primary immune deficiency disorders presenting as autoimmune diseases: IPEX and APECED

Background Several primary immune deficiency disorders are associated with autoimmunity and malignancy, suggesting a state of immune dysregulation. The concept of immune dysregulation as a direct cause of autoimmunity in primary immune deficiency disorders (PIDDs) has been strengthened by the recent discovery of distinct clinical entities linked to single-gene defects resulting in multiple autoimmune phenomena including immune dysregulation, polyendocrinopathy, enteropathy and X-linked (IPEX) syndrome, and autoimmune polyendocrinopathy, candidiasis and ectodermal dystrophy (APECED) syndrome. Conclusion Reviewing recent advances in our understanding of the small subgroup of PIDD patients with defined causes for autoimmunity may lead to the development of more effective treatment strategies for idiopathic human autoimmune diseases.

A novel STAT5B mutation causing GH insensitivity syndrome associated with hyperprolactinemia and immune dysfunction in two male siblings

Background: GH insensitivity (GHI) syndrome caused by STAT5B mutations was recently reported, and it is characterized by extreme short stature and immune dysfunction. Treatment with recombinant human IGF1 (rhIGF1) is approved for patients with GHI, but the growth response to this therapy in patients with STAT5B mutations has not been reported. Objectives: To report the clinical features, molecular findings, and the short-term growth response to rhIGF1 therapy in patients with STAT5B mutation. Subjects and methods: Hormonal and immunological evaluations were performed in two male siblings with GHI associated with atopic eczema, interstitial lung disease, and thrombocytopenic purpura. STAT5B genes were directly sequenced. The younger sibling was treated with rhIGF1 at a dose of 110 mu g/kg BID. Results: Both siblings had laboratory findings compatible with GHI associated with hyperprolactinemia. Lymphopenia and reduced number of natural killer cells without immunoglobulin abnormalities were observed. STAT5B sequence revealed a homozygous frameshift mutation (p.L142fsX161) in both siblings. The younger sibling (9.9 years of age) was treated with rhIGF1 at appropriate dosage, and he did not present any significant change in his growth velocity (from 2.3 to 3.0 cm/year after 1.5 years of therapy). The presence of a chronic illness could possibly be responsible for the poor result of rhIGF1 treatment. Further studies in patients with STAT5B defects are necessary to define the response to rhIGF1 treatment in this disorder. Conclusion: GHI associated with immune dysfunction, especially interstitial lung disease, and hyperprolactinemia is strongly suggestive of a mutation in STAT5B in both sexes.

Immunization with pVAXhsp65 Decreases Inflammation and Modulates Immune Response in Experimental Encephalomyelitis

Background: A DNA vaccine (pVAXhsp65) containing the gene of a heat-shock protein (hsp65) from Mycobacterium leprae showed high immunogenicity and protective efficacy against tuberculosis in BALB/c mice. A possible deleterious effect related to autoimmunity needed to be tested because hsp65 is highly homologous to the correspondent mammalian protein. In this investigation we tested the effect of a previous immunization with DNAhsp65 in the development of experimental autoimmune encephalomyelitis (EAE), a rat model of multiple sclerosis. Methods: Female Lewis rats were immunized with 3 pVAXhsp65 doses by intramuscular route. Fifteen days after the last DNA dose the animals were evaluated for specific immunity or submitted to induction of EAE. Animals were evaluated daily for weight loss and clinical score, and euthanized during the recovery phase to assess the immune response and inflammatory infiltration at the central nervous system. Results: Immunization with pVAXhsp65 induced a specific immune response characterized by production of IgG(2b) anti-hsp65 antibodies and IFN-gamma secretion. Previous immunization with pVAXhsp65 did not change EAE clinical manifestations (weight and clinical score). However, the vaccine clearly decreased brain and lumbar spinal cord inflammation. In addition, it downmodulated IFN-gamma and IL-10 production by peripheral lymphoid organs. Conclusion: Our data demonstrated that this vaccine does not trigger a deleterious effect on EAE development and also points to a potential protective effect. Copyright (C) 2010 S. Karger AG, Basel

Reappraisal of the immunopathogenesis of disseminated leishmaniasis: in situ and systemic immune response

Disseminated leishmaniasis (DL) is an emerging form of Leishmania braziliensis infection characterised by multiple cutaneous lesions on different parts of the body and a high rate of mucosal involvement. Systemic production of TNF alpha and IFN-gamma in DL patients is lower than in cutaneous leishmaniasis (CL) caused by L braziliensis, which may account for parasite dissemination due to the decreased ability to control parasite growth. In this study, the systemic and in situ immune response of DL and CL patients was characterised through evaluation of chemokine and cytokine production. In situ evaluation showed similar production of IFN gamma, TNF alpha, IL-10, transforming growth factor-beta (TGF beta), chemokine (C-C motif) ligand 2 (CCL2), CCL3, CCL11 and chemokine (C-X-C motif) ligand 10 (CXCL10) in papular and ulcerative lesions from DL as well as in ulcerated lesions from CL. Serum levels of CXCL9, a chemokine that attracts 1-cells, was higher in serum from DL than from CL These data indicate that a decrease in the type 1 immune response in peripheral blood of DL patients is due to attraction of Leishmania antigen-activated T-cells to the multiple cutaneous lesions. This may account for the absence of or few parasites in the lesions and for the development of ulcers similar to those observed in CL (C) 2011 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

Host genetic background affects regulatory T-cell activity that influences the magnitude of cellular immune response against Mycobacterium tuberculosis

Using two mouse strains with different abilities to generate interferon (IFN)-gamma production after Mycobacterium tuberculosis infection, we tested the hypothesis that the frequency and activity of regulatory T (Treg) cells are influenced by genetic background. Our results demonstrated that the suppressive activity of spleen Treg cells from infected or uninfected BALB/c mice was enhanced, inhibiting IFN-gamma and interleukin (IL)-2 production. Infected C57BL/6 mice exhibited a decrease in the frequency of lung Treg cells and an increased ratio CD4(+):CD4(+)Foxp3(+) cells compared with infected BALB/c mice and uninfected C57BL/6 mice. Moreover, infected C57BL/6 mice also had a decrease in the immunosuppressive capacity of spleen Treg cells, higher lung IFN-gamma and IL-17 production, and restricted the infection better than BALB/c mice. Adoptive transfer of BALB/c Treg cells into BALB/c mice induced an increase in bacterial colony-forming unit (CFU) counts. Furthermore, BALB/c mice treated with anti-CD25 antibody exhibited lung CFU counts significantly lower than mice treated with irrelevant antibody. Our results show that in BALB/c mice, the Treg cells have a stronger influence than that in C57BL/6 mice. These data suggest that BALB/c and C57BL/6 mice may use some different mechanisms to control M. tuberculosis infection. Therefore, the role of Treg cells should be explored during the development of immune modulators, both from the perspective of the pathogen and the host. Immunology and Cell Biology (2011) 89, 526-534; doi:10.1038/icb.2010.116; published online 19 October 2010

Indirect immune detection of ecdysone receptor (EcR) during the formation of DNA puffs in Bradysia hygida (Diptera, Sciaridae)

Gene amplification occurs in Bradysia hygida salivary glands, at the end of the fourth larval instar. The hormone 20-hydroxyecdysone (20E) triggers this process, which results in DNA puff formation. Amplified genes are activated in two distinct groups. The activity of the first group is dependent on high levels of 20E, while the second group needs low hormone levels. Consequently, the salivary glands of B. hygida constitute an interesting biological model to study how 20E, and its receptors, affect gene amplification and activity. We produced polyclonal antibodies against B. hygida EcR (BhEcR). In western blots a polypeptide of about 66 kDa was detected in salivary gland extracts. The antibodies were also used for indirect immune-localization of BhEcR in polytene chromosomes. RNA-polymerase II was also immune-detected. We did not detect the receptor in chromosome C where the first and second groups of DNA puffs form during DNA puff anlage formation, but it was present during puff expansion. During the active phase of both groups of DNA puffs, RNA polymerase II co-localized with BhEcR. After puff regression, these antigens were not detected. Apparently, EcR plays a direct role in the transcription of amplified genes, but its role in gene amplification remains enigmatic.

A BALB/c mouse model shows that liver involvement in dengue disease is immune-mediated

In the present study, BALB/c mice were used to develop a model for the hepatic injury associated to dengue infection. Histological analysis after subcutaneous inoculation with a low viral dose of dengue-2 virus showed Kupffer cell hyperplasia and an increased inflammatory cellular infiltrate next to the bile ducts on days 5, 7 and 14 post-inoculation, mainly characterized by the presence of mononuclear cells. The liver mRNA transcription level of IL-1 beta was highest on the 5th day post-infection (p.i.) and decreased by the 21st day, TNF-alpha showed a peak of mRNA transcription after 14 days p.i. coinciding with the regression of cellular infiltrates and elevated expression of TGF-beta mRNA. Serum AST and ALT levels were slightly elevated at 7 and 14 days post-infection. Dengue-2 RNA levels were undetectable in the liver on any of the days following inoculation. Our observations suggest that, as it is true for humans, the animals undergo a transient and slight liver inflammation, probably due to local cytokine production and cellular infiltration in the liver. (C) 2010 Elsevier Inc. All rights reserved.