As most human immunodeficiency virus (HIV) infection occurs via mucosal surfaces, an important goal of vaccination may be the induction of virus-specific immune responses at mucosal sites to contain viral infection early on. Here we designed a study in macaques carrying the major histocompatibility complex class I Mamu-A‫10ء‬ molecule to assess the capacity of the highly attenuated poxvirus NYVAC/simian immunodeficiency virus (SIV) SIV gpe vaccine candidate administered by the intranasal, intramuscular, or intrarectal route to induce mucosal immunity. All macaques, including one naive macaque, were exposed to SIV mac251 by the intrarectal route and sacrificed 48 h after infection. The kinetics of immune response at various time points following immunization with NYVAC/SIV gpe and the anamnestic response to SIV mac251 at 48 h after challenge were assessed in blood, in serial rectal and vaginal biopsy samples, and in tissues at euthanasia with an SIV mac Gag-specific tetramer. In addition, at euthanasia, antigen-specific cells producing gamma interferon or tumor necrosis factor alpha from the jejunum lamina propria were quantified in all macaques. Surprisingly, antigenspecific CD8؉ T cells were found in the mucosal tissues of all immunized macaques regardless of whether the vaccine was administered by a mucosal route (intranasal or intrarectal) or systemically. In addition, following mucosal SIV mac251 challenge, antigen-specific responses were mainly confined to mucosal tissues, again regardless of the route of immunization. We conclude that immunization with a live vector vaccine results in the appearance of CD8 ؉ T-cell responses at mucosal sites even when the vaccine is delivered by nonmucosal routes.

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BackgroundExperimental colitis with features similar to inflammatory bowel disease (IBD) has initially been described. A detailed analysis of inflammatory cells has not yet been described. Therefore in this study we characterized the cells involved in the acute phase of the colitis and compared those findings to what is known about human IBD.MethodsColitis was induced in BALB/C and C57Bl6 mice by ingestion of 2.5% and 5% DSS in the drinking water for 8 days. Cells were labelled by immunohistochemical staining with F4/80 and ER-MP20 for macrophages, TIB 120 for MHC Class II presentation, and anti-CD4 and anti-CD8 antibodies. They were enumerated by using a novel method that employs video image analysis. Immunoglobulin-producing cells were enumerated by immunofluorescent staining for IgA, IgG and IgM and counting by using confocal microscopy.ResultsInflammatory infiltrate in the acute phase of the dextran sulphate sodium (DSS) -induced colitis consists predominantly of macrophages, neutrophils and eosinophils. Neutrophils increase in numbers and crypt abscesses were also seen. Increased macrophage numbers were due to recently recruited monocytes from the peripheral circulation. It does not appear that there are any changes in T cell numbers or distribution. The inflammation induced changes in immunoglobulin-producing cells with IgA-producing cells affected the most.ConclusionsThe effect on Ig-producing cells depends on the percentage of DSS used to induce colitis. In general, 2.5% DSS induces an increase and 5% DSS a depletion of these cells.

The importance of IL-4 and its effects in inflammatory bowel disease (IBD) was studied using the dextran sulphate sodium-induced model of experimental colitis. The model resembles ulcerative colitis in humans. IL-4 deficient mice and IL-4+/+ littermates were used to induce colitis. Activity of disease, extent of tissue damage, immunoglobulin isotypes, IFNgamma and IL-10 production was assessed. Both disease activity index (DAI) and histological scores were consistently lower in the IL-4 deficient mice than in the IL-4+/+ littermates. Furthermore, the lower histological scores reflected the milder inflammatory lesions and decreased ulceration found in the IL-4 deficient mice. Analysis of immunoglobulin subtypes showed that IgG1 was almost absent in the sera of IL-4 deficient mice. IFNgamma contents was much higher in colonic tissues from IL-4 deficient mice. Dextran sulphate sodium-induced colitis is ameliorated in IL-4 deficient mice. IL-4 either directly or through its effects on T and B cells influences its severity. It is unclear if the higher immunoglobulin-producing cells in the colonic tissues of IL-4 deficient mice before colitis was induced could have influenced the outcome of the disease. The high IFNgamma contents in colonic tissues of IL-4 deficient mice argue against the role of this cytokine as a crucial mediator of tissue damage during the acute phase of colitis.

Bacteria and their products have been implicated in the pathogenesis of chronic Inflammatory Bowel disease. The aim of this study was to investigate the potential role of lipopolysaccharides (LPS) in the development of intestinal injury by comparing the effects of the dextran sodium sulphate (DSS)-induced model of colitis in LPS-sensitive and -insensitive mice. Experimental colitis was induced in LPS-sensitive mice (C3H/He) and their LPS-insensitive congenic strain (C3H/HeJ). Colitis was assessed clinically using a disease activity index (derived from the three main clinical signs; diarrhoea, rectal bleeding and weight loss) and by histological scoring of the diseased colon. The clinical signs and disease activity index did not differ between the LPS-sensitive and -insensitive costrains. Similarly, histological scores did not differ significantly for either C3H strain at any time point during exposure to DSS. However, there were differences in the inflammatory response when different strains were compared (C3H vs CBA): the effects of DSS in C3H mice were immediate, more severe and mainly involved the caecum and ascending colon. These findings suggest that LPS from colonic bacteria do not play a primary role in the initiation of DSS-induced colitis and demonstrate clear differences in the responsiveness of different mouse strains to DSS.

Most human immunodeficiency virus (HIV

Tissue eosinophilia is a feature of idiopathic inflammatory bowel disease and other forms of colonic inflammation but it is not clear whether the role of eosinophils in the disease process is to contribute to tissue damage. Interleukin 5 (IL-5) stimulates production and activation of eosinophils in vitro and enhances immunoglobulin A (IgA) production. As very little is known about the function of IL-5 in the colon, the aim of this study was to assess its role in colonic inflammation. IL-5 deficient mice were studied using the dextran sulphate sodium (DSS)-induced colitis model and the results compared to a congenic IL-5+/+ strain. The absence of IL-5 resulted in reduction of tissue eosinophilia (P Ͻ 0.0001) but was not reflected in differences in the severity of the disease (P Ͼ 0.5) or in the extent of tissue damage in this model of colitis. Numbers of immunoglobulin-containing cells in IL-5 deficient mice were similar to those in the IL-5+ mice. We conclude that the main role of IL-5 in DSS-induced colonic inflammation is to attract a population of eosinophils which do not appear to contribute significantly to the initiation or development of tissue damage in this model of colitis. Genes and Immunity (2000) 1, 213-218.

The identification of several simian immunodeficiency virus mac251 (SIV mac251 ) cytotoxic T-lymphocyte epitopes recognized by CD8؉ T cells of infected rhesus macaques carrying the Mamu-A*01 molecule and the use of peptide-major histocompatibility complex tetrameric complexes enable the study of the frequency, breadth, functionality, and distribution of virus-specific CD8 ؉ T cells in the body. To begin to address these issues, we have performed a pilot study to measure the virus-specific CD8؉ and CD4 ؉ T-cell response in the blood, lymph nodes, spleen, and gastrointestinal lymphoid tissues of eight Mamu-A*01-positive macaques, six of those infected with SIV mac251 and two infected with the pathogenic simian-human immunodeficiency virus KU2. We focused on the analysis of the response to peptide p11C, C-M (Gag 181), since it was predominant in most tissues of all macaques. Five macaques restricted viral replication effectively, whereas the remaining three failed to control viremia and experienced a progressive loss of CD4 ؉ T cells. The frequency of the Gag 181 (p11C, C3M) immunodominant response varied among different tissues of the same animal and in the same tissues from different animals. We found that the functionality of this virus-specific CD8 ؉ T-cell population could not be assumed based on the ability to specifically bind to the Gag 181 tetramer, particularly in the mucosal tissues of some of the macaques infected by SIV mac251 that were progressing to disease. Overall, the functionality of CD8 ؉ tetramer-binding T cells in tissues assessed by either measurement of cytolytic activity or the ability of these cells to produce gamma interferon or tumor necrosis factor alpha was low and was even lower in the mucosal tissue than in blood or spleen of some SIV mac251 -infected animals that failed to control viremia. The data obtained in this pilot study lead to the hypothesis that disease progression may be associated with loss of virus-specific CD8 ؉ T-cell function.