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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The gut associated lymphoid tissue is responsible for specific responses to intestinal antigens. During HIV infection, mucosal immune deficiency may account for the gastrointestinal infections. In this review we describe the humoral and cellular mucosal immune responses in normal and HIV-infected subjects.
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PMID:Gastrointestinal immune responses in HIV infected subjects. 904 Aug 57

Good protection against systemic challenge in the SIVmac model of AIDS has been provided by prior infection with attenuated virus. To determine if such protection extends to intrarectal mucosal challenge two molecular clones, SIVmacC8 and SIVmacJ5, were used in this study. SIVmacC8 has an attenuated phenotype in vivo, due to a 12-bp deletion in the nef/ 3'-LTR, whereas SIVmacJ5 has a full size nef open reading frame and induces AIDS in infected macaques. The J5 molecular clone was shown to infect rhesus macaques following atraumatic intrarectal inoculation. The dynamics were similar to those following intravenous inoculation resulting in early, high, cell-associated viremia and seroconversion. Four macaques previously infected with the attenuated SIVmacC8 resisted superinfection with SIVmacJ5, following intrarectal inoculation. These animals also resisted intrarectal infection with an HIV/SIV chimeric virus (SHIV) composed of SIVmac239 expressing the HXBc2 env, tat, and rev genes, suggesting that immunity to the envelope proteins was unlikely to be involved in the superinfection resistance. Infection with the attenuated SIVmac generated cytotoxic T lymphocytes (CTL) detectable in the peripheral circulation, serum neutralizing antibodies, and SIV-binding antibodies in rectal fluids. SIVmacC8 proviral DNA was found in lymph nodes removed at necropsy but there was no evidence for local sequestration of challenge virus. SIV-specific CTL, were detected in gut-associated lymph nodes and may have a role in limiting superinfection following mucosal exposure.
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PMID:Macaques infected with live attenuated SIVmac are protected against superinfection via the rectal mucosa. 912 56

The objective of this study was to determine the initial and subsequent phenotypes of HIV-1 isolated from the blood, duodenal, and colonic biopsies of 51 HIV-1 positive patients followed prospectively over 2 years. Blood and tissues were cocultured with stimulated peripheral blood monocytes, and HIV was analyzed for phenotypic expression of syncytia-induction (SI). A total of 45/51 patients had HIV-1 isolated from the blood and 35/51 had HIV isolated from gastrointestinal tract. In 12/45 patients SI-HIV-1 was isolated from the blood. In 6/12 patients the blood phenotype reverted to the NSI phenotype. SI phenotypes were also isolated from the colon and duodenum of 8/35 patients and reversion from SI to NSI virus phenotype was again observed in gut tissue of 3/8 patients. These results show that gastrointestinal tissues can harbor SI HIV phenotype. Discordant phenotypes can be found in tissue and blood of late-stage patients. Reversion of phenotypic SI expression to NSI may occur in patients receiving monotherapy as antiretroviral treatment. These results suggest that gastrointestinal tissues may act as a separate and distinct site involved in HIV replication and its associated pathogenesis.
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PMID:Phenotypic variations and switches in HIV isolated from the blood and the gastrointestinal tissues of patients with HIV-1 infection. HIV/GI Research Study Group. 913 55

Although there have been dramatic strides in the therapy of human immunodeficiency virus infection over the last few years, the number of infected people world-wide is tremendous and, at least in developing countries, continues to expand. Complications which involve the gastrointestinal tract are common in these patients, because the gut is a major site for involvement by opportunistic infections and neoplasms in patients with the acquired immunodeficiency syndrome. It is important to recognize the clinical spectrum of gastrointestinal diseases, as well as the appropriate and most cost-effective diagnostic strategies, as therapies for a number of these disorders are both widely available and high effective. This review summarizes the major gastrointestinal infections which are seen in patients with the acquired immunodeficiency syndrome, and their treatment.
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PMID:Review article: the therapy of gastrointestinal infections associated with the acquired immunodeficiency syndrome. 921 66

Honduras has at least five-times more human immunodeficiency virus (HIV)-infected individuals than any other country in Central America. The relationship between HIV status and the presence of intestinal parasites in this part of the world is unknown. This study presents the results from a prospective, comparative study for the presence of parasites in 52 HIV-positive and 48 HIV-negative persons in San Pedro Sula, Honduras. Infection with HIV was determined by microagglutination and confirmed by Western blot analysis. Parasites were detected in stools using formalin-ether concentration, and Kinyoun and trichrome staining. Age, sex, and clinical state of HIV infection were recorded for each study participant. Our results indicate that Cryptosporidium parvum and Strongyloides stercoralis, which are intracellular or live in the mucosa, were found exclusively in persons infected with HIV. In comparison, the prevalence of the extracellular parasites Giardia lamblia, Ascaris lumbricoides, and Trichuris trichiura was significantly higher (P < 0.05) in persons who were HIV-negative. Trichuris worms are in contact with the gut epithelium and less so with the mucosa, whereas Strongyloides lives within the gut mucosa. It is possible that changes in the gut epithelium due to HIV infection do not affect the mucosa and therefore would not affect Strongyloides. We conclude that infection with HIV may selectively deter the establishment of certain intestinal parasites. This may be due to the fact that HIV-induced enteropathy does not favor the establishment of extracellular parasites. Intracellular and mucosal dwelling organisms, however, may benefit from pathologic changes and reduced local immune responses induced by the virus, which, in turn, may lead to higher prevalence among HIV-infected individuals.
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PMID:Intestinal parasitic infections in human immunodeficiency virus (HIV)-positive and HIV-negative individuals in San Pedro Sula, Honduras. 957 87

There is an interesting relationship between the HIV virus, the health of the gastrointestinal tract, and AIDS wasting syndrome, involving Tumor Necrosis Factor alpha (TNF alpha), specific and non-specific immunity in the gut, gut permeability, and oxidative stress. It is hypothesized that the progression of HIV to full-blown AIDS may be impacted by maintaining a healthy gut. A therapeutic protocol which decreases oxidative stress, inhibits TNF alpha, enhances phase I and II liver detoxification, and improves specific and non-specific immunity in the gut should be part of a therapeutic protocol for HIV-infected individuals. Through a better understanding of the pathophysiology of HIV advancing to AIDS, the practitioner can develop a treatment strategy of nutritional and lifestyle changes which could theoretically prevent an HIV infection from advancing to full-blown AIDS.
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PMID:AIDS wasting syndrome as an enterometabolic disorder: the gut hypothesis. 960 25

Lymphocytes stay in the blood only a short time before migrating to lymphoid and nonlymphoid organs. They represent only about 2% of all lymphocytes in the body. The ratio of CD4+/CD8+ lymphocytes in the blood depends on age and genetic influences. In HIV infection not only relative but also absolute numbers of lymphocyte subsets should be determined. The different effects of proliferation and apoptosis on lymphocytes in HIV infection have to be considered. Lymphocyte levels in the blood of HIV patients do not mirror alterations in the lamina propria of the gut or lymph nodes. The dynamic aspects of lymphocyte life span and migration during HIV infection and the progression to AIDS as well as the effects of treatment have to be taken into consideration to enable a meaningful interpretation of experimental data. More data from animal models of HIV infection are needed to study these kinetic aspects.
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PMID:Interpreting data on lymphocyte subsets in the blood of HIV patients - organ distribution, proliferation and migration kinetics are critical factors. 969 10

The human thymus is a lymphoepithelial organ in which T cells develop during fetal life. After maturation and selection in the fetal thymic microenvironment, T cells emigrate to peripheral lymphoid tissues such as the spleen, gut, and lymph nodes, and establish the peripheral T cell repertoire. Although the thymus has enormous regenerative capacity during fetal development, the regenerative capacity of the human postnatal thymus decreases over time. With the advent of intensive chemotherapy regimens for a variety of cancer syndromes, and the discovery that infection with the Human Immunodeficiency Virus (HIV) leads to severe loss of CD4+ T cells, has come the need to understand the role of the human thymus in reconstitution of the immune system in adults. During a recent study of the thymus in HIV infection, we observed many CD8+ T cells in AIDS thymuses that had markers consistent with those of mature effector cytotoxic T cells usually found in peripheral immune tissues, and noted these CD8+ effector T cells were predominately located in a thymic zone termed the thymic perivascular space. This article reviews our own work on the thymus in HIV-1 infection, and discusses the work of others that, taken together, suggest that the thymus contains peripheral immune cell components not only in the setting of HIV infection, but also in myasthenia gravis, as well as throughout normal life during the process of thymus involution. Thus, the human thymus can be thought of as a chimeric organ comprised of both central and peripheral lymphoid tissues. These observations have led us to postulate that the thymic epithelial atrophy and decrease in thymopoiesis that occurs in myasthenia gravis, HIV-1 infection, and thymic involution may in part derive from cytokines or other factors produced by peripheral immune cells within the thymic perivascular space.
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PMID:The human thymus. A chimeric organ comprised of central and peripheral lymphoid components. 995 49

The identification of mucosal immune responses required for protection against sexual transmission of HIV is essential for the development of an efficacious vaccine. To gain a better understanding of these responses, we have characterized the immune responses in the lamina propria (LP) and epithelium of the jejunum, the mesenteric lymph nodes, and peripheral blood (PBMC) of 11 rhesus monkeys following colonic exposure to two molecular clones of SIV. Two monkeys had no signs of infection. Three monkeys became persistently infected. Transient infections, characterized by the sporadic detection of virus in the periphery and/or detection of SIV-specific immune responses in either the gut-associated tissues or PBMC, were induced in six of the monkeys. One persistently infected and three transiently infected monkeys had high levels of SIV env-specific MHC class I restricted CTL in the jejunal LP. Another transiently infected monkey had SIV-specific IgA secreting B cells in the LP. Three or six months postexposure, these animals and four naive controls were challenged intracolonically with the heterologous primary isolate, SIV/DeltaB670. All four monkeys with strong SIV env-specific MHC-restricted CTL in the LP were protected, whereas none of the naive controls or the remaining seven monkeys with little or no CTL in the LP were protected. These experiments provide the first direct evidence that transient mucosal infection can induce SIV-specific immunity that remains localized to the gut-associated tissues. Furthermore, a strong correlation between SIV env-specific MHC-restricted CTL in the LP and protection against colonic mucosal challenge was observed.
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PMID:Selective induction of protective MHC class I-restricted CTL in the intestinal lamina propria of rhesus monkeys by transient SIV infection of the colonic mucosa. 988 31

Evidence is increasing that HIV/SIV-induced changes in the highly differentiated gut-associated immune system play a central role in the pathogenesis of gastrointestinal manifestations in HIV/SIV infection. It has been shown in both humans infected with HIV and in nonhuman primates infected with SIV that a rapid, very early, and more pronounced loss of CD4+ T-cells occurs in the mucosa in comparison to the peripheral blood. The loss of this important regulatory T-cell subset might explain mucosal immunodeficiency with the consequence of opportunistic mucosal infections. In addition, there is evidence that small intestinal damage occurs independently of secondary infections (HIV/SIV enteropathy). In late-stage human disease, HIV enteropathy is characterized by villous atrophy with hyporegeneration and dysmaturation of intestinal epithelial cells. In SIV infection of macaques, villous atrophy is a very early event; however, it is accompanied by crypt cell hyperproliferation. Early- and late-stage enteropathy in immunodeficiency virus infection may represent two types of immunologically mediated mucosal transformation in which the number and state of activation of regulatory T cells determine whether hypo- or hyperproliferative villous atrophy occurs.
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PMID:HIV/SIV enteropathy. 992 77


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