The immunopathogenesis of human immunodeficiency virus infection

Upregulation of Fas ligand expression by human immunodeficiency virus in human macrophages mediates apoptosis of uninfected T lymphocytes

Apoptosis has been proposed to mediate CD4+ T-cell depletion in human immunodeficiency virus (HIV)-infected individuals. Interaction of Fas ligand (FasL) with Fas (CD95) results in lymphocyte apoptosis, and increased susceptibility to Fas-mediated apoptosis has been demonstrated in lymphocytes from HIV-infected individuals. Cells undergoing apoptosis in lymph nodes from HIV-infected individuals do not harbor virus, and therefore a bystander effect has been postulated to mediate apoptosis of uninfected cells. These data raise the possibility that antigen-presenting cells are a source of FasL and that HIV infection of cells such as macrophages may induce or increase FasL expression. In this report, we demonstrate that HIV infection of monocytic cells not only increases the surface expression of Fas but also results in the de novo expression of FasL. Interference with the FasL-Fas interaction by anti-Fas blocking antibodies abrogates HIV-induced apoptosis of monocytic cells. Human monocyte-derived macrophages from healthy donors contain detectable FasL mRNA, which is further upregulated following HIV infection with monocytotropic strains. HIV-infected human macrophages result in the apoptotic death of Jurkat T cells and peripheral blood T lymphocytes. Interruption of the FasL-Fas interaction abrogates the HIV-infected macrophage-dependent death of T lymphocytes. These results provide evidence that human macrophages can provide a source of FasL, especially following HIV infection, and can thus participate in lymphocyte depletion in HIV-infected individuals.

Impaired antibody responses and loss of reactivity to Onchocerca volvulus antigens by HIV-seropositive onchocerciasis patients

The impact of concomitant human immunodeficiency virus (HIV) infection on the antibody response of onchocerciasis patients to Onchocerca volvulus antigens (OvAg) was studied by Western blotting and enzyme linked immunosorbent assay (ELISA). Immunoglobulin G (IgG) antibodies in sera from 45 HIV-sero-positive O. volvulus microfilariae (mf) carriers (HIV+/Ov+) recognized significantly fewer distinct O. volvulus antigenic bands, and responded less frequently to all detected bands compared to sera from 61 matched HIV-seronegative mf carriers (HIV-/Ov+). 29% of 31 follow-up sera from the HIV+/Ov+ patients failed to react to many of the antigenic bands recognized by initial sera from the same patients. Among 4 HIV+/Ov+ persons examined for total CD4+ cells, loss of reactivity corresponded with low CD4+ total cell counts. In an OvAg ELISA, sera from the HIV+/Ov+ individuals had significantly lower IgG+IgM antibody levels than sera from the HIV-/Ov+ persons, and the sensitivity of the assay was 87% for the HIV+/Ov+ subjects compared to 100% for those who were HIV-/Ov+. It is concluded that HIV-infected onchocerciasis patients exhibit significantly impaired antibody responses to O. volvulus antigens, and tend to lose their reactivity to these antigens over time due to immune response abnormalities caused by the concomitant HIV infection.

Immunological and virological markers of HIV-disease progression

This review, based upon scientific literature, evaluates a number of immunological and virological markers for their usefulness as prognostic indicators for progression of HIV disease. The most widely studied marker, the CD4 positive T lymphocyte count, is perhaps the best single indicator of stage of illness. Serum factors such as neopterin and beta-2 microglobulin, alone and in combination with CD4 cell counts, have been shown to have good predictive value. Measurement of viral burden by quantification of viral RNA levels in plasma and immune cells also holds promise for following disease progression. It is recommended that a combination of these factors be monitored in evaluating stage of illness and responses to therapy in HIV-infected persons.

Molecular biology and pathogenesis of animal lentivirus infections

Lentiviruses are a subfamily of retroviruses that are characterized by long incubation periods between infection of the host and the manifestation of clinical disease. Human immunodeficiency virus type 1, the causative agent of AIDS, is the most widely studied lentivirus. However, the lentiviruses that infect sheep, goats, and horses were identified and studied prior to the emergence of human immunodeficiency virus type 1. These and other animal lentiviruses provide important systems in which to investigate the molecular pathogenesis of this family of viruses. This review will focus on two animal lentivirus models: the ovine lentivirus visna virus; and the simian lentivirus, simian immunodeficiency virus. These animal lentiviruses have been used to examine, in particular, the pathogenesis of lentivirus-induced central nervous system disease as models for humans with AIDS as well as other chronic diseases.

Relationship between tumor necrosis factor alpha and feline immunodeficiency virus expressions

The presence of feline immunodeficiency virus (FIV) proviral DNA, expression of FIV p26 core protein, and production of tumor necrosis factor alpha (TNF-alpha) were assessed in sequential biopsies of spleen and lymph node sections, of mononuclear cells of the peripheral blood, and of the serum of specific-pathogen-free cats during the acute phase of FIV infection. A temporal relationship between TNF-alpha production and FIV p26 expression was noted. Two months following FIV infection, and preceding the detection of FIV viremia, levels of TNF-alpha in serum increased significantly (P = 0.04), and they remained elevated during FIV viremia in the third month postinfection. Immunoprecipitates representing expression of TNF-alpha and of FIV p26 were localized in common foci of lymph nodes of FIV-infected cats during this period of active viremia. With the advent of anti-FIV antibodies, circulating levels of TNF-alpha and p26 antigen and expression of TNF-alpha and p26 in the lymph nodes decreased during the fifth month postinfection, and p26 production became undetectable. With clearance of viremia, burden of proviral DNA in peripheral blood mononuclear cells became reduced (P = 0.041), with provirus remaining integrated principally within lymph nodes (P = 0.046). During aviremia, p26 expression was undetectable in any tissue but remained inducible in vitro. During acute FIV infection, TNF-alpha production and p26 expression are intimately linked.

Prospective characterization of the clinicopathologic and immunologic features of an immunodeficiency syndrome affecting juvenile llamas

The clinicopathologic and immunologic features of 15 llamas affected with juvenile llama immunodeficiency syndrome (JLIDS) are described. Healthy adult (n = 10) and juvenile (n = 10) llamas served as controls. JLIDS llamas were characterized by wasting, and clinically apparent, repeated infections were frequently observed. The median age at which a health problem was first perceived was 11.6 months. All 15 affected llamas died or were killed, and JLIDS was confirmed at necropsy. The median duration of illness was 3.5 months. Lymphocyte blastogenesis assays showed suppressed responses (particularly to Staphylococcus sp. Protein A) in JLIDS llamas. No evidence of retroviral infection was detected. Mild, normocytic, normochromic, non-regenerative anemia, low serum albumin concentration and low to low-normal globulin concentrations were typically found on initial clinical evaluation. Lymph node biopsies showed areas of paracortical depletion. All llamas affected with JLIDS had low serum IgG concentrations, pre-vaccination titers against Clostridium perfringens C and D toxoids of < or = 1:100, and no titer increase following vaccination.

Similar patterns of simian immunodeficiency virus env sequences are found in the blood and lymphoid tissues of chronically infected macaques

Two cynomolgus macaques were infected with a genetically complex challenge stock of simian immunodeficiency virus (SIVmac251-32H). One animal developed SIV-induced disease and was sacrificed at 16 months postinfection. The second remained healthy until it too was sacrificed at 20 months postinfection. The polymerase chain reaction (PCR) was used to amplify env gp120-coding sequences from provirus present in samples of blood, spleen, and inguinal lymph node taken from both animals on the day of sacrifice. The proviral burden present in each of the tissue samples was also determined using a quantitative PCR assay. The proviral burdens in the blood, spleen, and inguinal lymph node of the healthy animal (I225) were similar. This was not the case for animal I227, in which the burden in the inguinal lymph node was much higher than for blood or spleen. Phenogram analysis of the hypervariable V1 region of env revealed that the diversity of nucleotide sequences recovered from each tissue of both macaques were similar and overlapping. Some selected amino acid differences were observed that were specific for a tissue or one of the macaques. However, the results do not suggest that the overall evolution of env in provirus populations recovered from lymphoid tissues is distinct from that recovered from the blood.

Intracellular immunization against HIV-1 infection of human T lymphocytes: utility of anti-rev single-chain variable fragments

Genetic therapy offers a potentially promising approach with which to combat human immunodeficiency virus type 1 (HIV-1) infections. Several modalities, using protein- and RNA-based systems, have recently been shown to inhibit HIV-1 replication. A single-chain variable fragment (SFv), constructed from the cDNA of a monoclonal antibody to the HIV-1 regulatory protein Rev, has been demonstrated to potently inhibit HIV-1 replication, when expressed intracellularly in an epithelial cell-line (HeLa-CD4). Murine retroviral shuttle vectors, which express the anti-Rev SFv moiety, have now been constructed. HIV-1 infection was dramatically inhibited in human T-lymphocytic cell-lines, CEM and Sup-T1, transduced with these anti-Rev SFv-expressing vectors. This resistance to high levels of HIV-1 expression was demonstrated in both mixed populations and clones of these cells. Of further potential clinical significance, HIV-1 infection was also potently inhibited in human peripheral blood mononuclear cells (PBMC), transduced with retroviral vectors expressing the anti-Rev SFv molecule. These data suggest that intracellular expression of anti-Rev SFvs, or related approaches, may be utilized as genetic therapy, or intracellular immunization, for HIV-1 infections in vivo.

Human immunodeficiency virus type 1 Vpr arrests the cell cycle in G2 by inhibiting the activation of p34cdc2-cyclin B

Human immunodeficiency virus type 1 (HIV-1) vpr inhibits the replication of tumor cell lines and peripheral blood mononuclear cells. Here it is demonstrated that expression of vpr, either in the context of a provirus or from an independent genetic element, induces a discrete cell cycle arrest, with cells containing 4N DNA. Low cyclin B-associated kinase activity, as well as the status of p34cdc2 and cdc25C phosphorylation, indicates that the cascade of reactions which drives the cell into mitosis has not been initiated. The phosphatase inhibitor okadaic acid releases the block, suggesting that Vpr perturbs upstream regulatorsof the G2-M transition. These studies demonstrate that HIV-1 vpr has profound effects on the cellular factors which control entry into mitosis and indicate vpr's potential contribution to the cellular pathology associated with HIV-1 infection.

HIV preventive vaccines. Progress to date

The major conceptual problem for HIV vaccine development has been the lack of information on immune responses known to correlate with protection against HIV infection in humans. In this regard, studies on the natural history of HIV infection and AIDS, especially of people with apparent resistance to HIV infection and of patients with HIV infection who have long term survival without disease progression, may provide important information for vaccine development. In addition, a major concern for the development of broadly effective vaccines has been the extensive genetic variability which is characteristic of HIV. In spite of these unknowns, the first generation of HIV candidate vaccines has been developed and evaluated. HIV candidate vaccines based on the subunit recombinant envelope concept (gp120 or gp160) have been shown to protect chimpanzees from HIV infection on challenge, and have now been evaluated in humans in phase I and phase II trials. These products are well tolerated, and capable of inducing neutralising antibodies, but not cytotoxic T lymphocytes. A second vaccine concept, currently in phase I trials, is based on live recombinant vectors, especially using poxvirus vectors followed by boosting with subunit recombinant envelope vaccines. This concept is theoretically very attractive because preliminary data suggest that these vaccines induce both humoral and cell-mediated immunity. However, no published information is available on the ability of live recombinant vector vaccines to protect chimpanzees from HIV infection. The next step in HIV vaccine development is to proceed carefully to expanded phase II and phase III trials to assess the protective efficacy of these candidate vaccines in humans. These trials will be extremely complex from the logistical, scientific and ethical points of view, and will require close collaboration between clinical, basic science and behavioural researchers, national and international organisations, and the pharmaceutical industry.

Human immunodeficiency virus infection and human African trypanosomiasis: a case-control study in Côte d'Ivoire

To assess the association between human immunodeficiency virus (HIV) infection and human African trypanosomiasis (HAT) in Côte d'Ivoire, West Africa, a cross-sectional case-control study was conducted on 301 HAT patients recruited in the main foci of the country. For each HAT patient, 3 controls, matched for sex, age and residence, were selected. Data relating to socio-demographic factors and potential risk factors for Trypanosoma brucei gambiense and HIV infections were obtained, and serum samples were collected for HIV-1 and HIV-2 tests. A positive test consisted of enzyme immunoassay reactive to HIV-1, HIV-2 or both and confirmed by a synthetic peptide test or Western blot. Data were analyzed using conditional logistic regression with EGRET software. No statistically significant difference was found between the prevalence of HIV infection in HAT patients and controls (4.3% and 3.5% respectively; crude odds ratio (OR) 1.28, 95% confidence interval (CI) 0.65-2.50). In multivariate analysis, allowance for 5 covariates did not change the association between the 2 infections (adjusted OR 1.27, 95% CI 0.64-2.52). Although this study had limited statistical power, no significant association was found between HIV infection and T.b. gambiense infection in rural Côte d'Ivoire. Studies are needed to determine whether HIV infection influences the clinical course of HAT, a question not addressed in the present study.

Contact of human immunodeficiency virus type 1-infected and uninfected CD4+ T lymphocytes is highly cytolytic for both cells

Individuals infected with the human immunodeficiency virus (HIV) experience a marked loss of CD4+ T lymphocytes, leading to fatal immunodeficiency. The mechanisms causing the depletion of these cells are not yet understood. In this study, we observed that CD4+ T lymphocytes from HIV type 1 (HIV-1)-infected and uninfected individuals rapidly lysed B lymphoblasts expressing the HIV-1 envelope glycoprotein on the cell surface and Jurkat cells expressing the complete virus. Contact of uninfected CD4+ T cells with envelope glycoprotein-expressing cells also resulted in the lysis of the uninfected CD4+ T cells. Cytolysis did not require priming or in vitro stimulation of the CD4+ T cells and was not restricted by major histocompatibility complex molecules. Cytotoxicity was inhibited by soluble CD4 and anti-CD4 monoclonal antibodies that block binding of CD4 to gp120. In addition, neutralizing anti-CD4 and anti-gp120 monoclonal antibodies which block postbinding membrane fusion events and syncytium formation also inhibited cell lysis, suggesting that identical mechanisms in HIV-infected cultures underlie cell-cell fusion and the cytolysis observed. However, cytotoxicity was not always accompanied by the formation of visible syncytia. Rapid cell lysis after contact of uninfected and HIV-1-infected CD4+ T cells may explain CD4+ T-cell depletion in the absence of detectable syncytia in infected individuals. Moreover, because of its vigor, lysis of envelope-expressing targets by contact with unprimed CD4+ T lymphocytes may at first glance resemble antigen-specific immune responses and should be excluded when cytotoxic T-lymphocyte responses in infected individuals and vaccinees are evaluated.

Syncytium induction in primary CD4+ T-cell lines from normal donors by human immunodeficiency virus type 1 isolates with non-syncytium-inducing genotype and phenotype in MT-2 cells

Human immunodeficiency virus type 1 (HIV-1) isolates classified as syncytium-inducing (SI) or non-SI (NSI) in the MT-2 T-cell line exhibit characteristic sequence differences in the V1-V2 and V3 regions of the env gene. Seven HIV-1 isolates were phenotyped as NSI or SI in the MT-2 cell line. Unexpectedly, all four NSI viruses induced large syncytia 4 to 8 days postinoculation in a panel of five primary CD4+ T-cell lines (including two clones) generated from the peripheral blood of normal donors by exposure to infectious HIV-1, inactivated HIV-1, or Epstein-Barr virus. The primary T-cell lines yielded neither HIV-1 provirus nor infectious HIV by PCR analysis or exhaustive coculture with phytohemagglutinin-treated blast cells. Three isolates (TC354, PK1, and PK2) were biologically cloned and retained their SI or NSI phenotypes in MT-2 and primary T-cell lines. The biologically cloned provirus DNA was also used to clone and sequence the relevant V2 and V3 regions of the env genes. The amino acid sequences of the V2 and V3 regions were characteristic of patterns already reported for the NSI, switch NSI, and SI phenotypes, respectively. This evidence precludes the possibility that these results were due to contamination of the NSI isolates with SI virus. The results unequivocally indicate that HIV-1 isolates with the NSI genotype and phenotype in MT-2 cells may actively induce syncytia in cloned CD4+ T cells in vitro and support the view that direct cytopathic effects may contribute to the steady decline in CD4+ T cells in asymptomatic HIV-1-seropositive patients without detectable SI virus.

Immunological characteristics of HIV-infected children: relationship to age, CD4 counts, disease progression, and survival

We have evaluated immunologic markers of disease progression in 79 children perinatally infected with HIV. Laboratory testing included T lymphocyte subsets and lymphoproliferative responses (LPR) to mitogens (PHA, Con A, and PWM), antigens (Candida, Tetanus), and alloantigens (MLC). Patients were graded into grades I, II, and III based on results of CD4 counts, and into grades A, B, and C based on results of LPR, with grades I and grades A being normal, III and C being the lowest, and II and B falling in-between. CD4 counts, CD4/CD8 ratio, and lymphoproliferative responses were markedly decreased in a majority of children. Grade III CD4 counts were almost always associated with decreased LPR. A majority of the children with grade I CD4 numbers, however, also had abnormal lymphoproliferative responses. Results of laboratory testing were analyzed in relation to clinical disease progression and survival. The first AIDS defining illnesses (ADI), especially opportunistic infections (OI), was usually associated with Grade III/C results in immunologic assays. Survival was significantly decreased in children with grade III CD4 cell counts, and grade C LPR, and was poorest if these abnormalities developed within the first year of life. In this latter age group, if the CD4 counts fell to grade III, the risk for dying was at least five times greater than those children with higher CD4 counts (grades II and I); if the proliferative responses to PHA and MLC were in Grade C, the survival was 22 months. Severe immune defects in the first year of life in children with HIV infection, as assessed by CD4 counts and a battery of functional tests, predicted rapid disease progression.

The human immunodeficiency virus type 1 vpr gene arrests infected T cells in the G2 + M phase of the cell cycle

Human immunodeficiency virus type 1 (HIV-1) infection causes profound immunological defects in afflicted patients. Various mechanisms have been proposed to account for the immune dysfunction in AIDS ultimately leading to loss of CD4+ T cells, including HIV-1 envelope-mediated syncytium formation, apoptosis, and cytokine modulation. Here we present results which suggest a novel hypothesis for T-cell dysfunction. We show, using HIV-1 bearing a novel cell surface reporter gene, that infected cells are unable to progress normally through the cell cycle and became arrested in the G2 + M phase. Furthermore, we identify the HIV-1 vpr gene product as being both necessary and sufficient for eliciting this cell cycle arrest. Cell cycle arrest induced by Vpr correlates with an increase in the hyperphosphorylated (inactive) form of the cyclin-dependent serine/threonine kinase CDC2, consistent with an arrest of cells at the boundary of G2 and M.

Induction of accelerated feline immunodeficiency virus disease by acute-phase virus passage

Development of feline immunodeficiency virus (FIV) infection in cats as a small animal model for lentiviral immunodeficiency disease has been hampered by the prolonged and variable disease course following experimental infection. To address this issue, we generated high-titer, unselected FIV stocks by pooling plasma from cats acutely infected with a subgroup C FIV isolate designated CABCpadyOOC (FIV-C-PGammer). Subsequent infection with this virus pool resulted in rapidly progressive, fatal disease in greater than 50% of infected cats. Accelerated FIV disease was characterized by rapid and progressive CD4+ T-cell loss, lymphadenopathy, weight loss, lymphoid depletion, and severe thymic atrophy. Mortality and rate of disease progression were affected by the age of each cat at infection and whether the virus source animal was in the acute or chronic stage of infection. The rapid FIV disease syndrome was consistently associated with systemic lymphoid depletion, clinical disease, and susceptibility to opportunistic infections, analogous to accelerated and/or terminal HIV-1 infection. The results of this study demonstrate that FIV infection is a valid small animal model for lentiviral immunodeficiency disease.

Viral infection and cancer

Infection with specific viruses has a role in the pathogenesis of some cancers in human beings. However, the incidence of such cancers is much lower than the frequency of virus infection, suggesting either that infection alone does not result in cancer and that cellular events in addition to the presence of the virus must occur, or that cancer occurs only if viral proteins are expressed in an appropriate cell type or in an immunocompromised host. Molecular analysis of viruses found in association with cancer has revealed that they function, at least in part, by encoding proteins which can associate with and subvert the function of host cell-encoded tumour suppressor proteins which regulate pathways of growth arrest and apoptosis. Better understanding of the mechanisms underlying this association will have diagnostic, prognostic, and therapeutic implications in the near future.

Regulation of human immunodeficiency virus type 1 and cytokine gene expression in myeloid cells by NF-kappa B/Rel transcription factors

CD4+ macrophages in tissues such as lung, skin, and lymph nodes, promyelocytic cells in bone marrow, and peripheral blood monocytes serve as important targets and reservoirs for human immunodeficiency virus type 1 (HIV-1) replication. HIV-1-infected myeloid cells are often diminished in their ability to participate in chemotaxis, phagocytosis, and intracellular killing. HIV-1 infection of myeloid cells can lead to the expression of surface receptors associated with cellular activation and/or differentiation that increase the responsiveness of these cells to cytokines secreted by neighboring cells as well as to bacteria or other pathogens. Enhancement of HIV-1 replication is related in part to increased DNA-binding activity of cellular transcription factors such as NF-kappa B. NF-kappa B binds to the HIV-1 enhancer region of the long terminal repeat and contributes to the inducibility of HIV-1 gene expression in response to multiple activating agents. Phosphorylation and degradation of the cytoplasmic inhibitor I kappa B alpha are crucial regulatory events in the activation of NF-kappa B DNA-binding activity. Both N- and C-terminal residues of I kappa B alpha are required for inducer-mediated degradation. Chronic HIV-1 infection of myeloid cells leads to constitutive NF-kappa B DNA-binding activity and provides an intranuclear environment capable of perpetuating HIV-1 replication. Increased intracellular stores of latent NF-kappa B may also result in rapid inducibility of NF-kappa B-dependent cytokine gene expression. In response to secondary pathogenic infections or antigenic challenge, cytokine gene expression is rapidly induced, enhanced, and sustained over prolonged periods in HIV-1-infected myeloid cells compared with uninfected cells. Elevated levels of several inflammatory cytokines have been detected in the sera of HIV-1-infected individuals. Secretion of myeloid cell-derived cytokines may both increase virus production and contribute to AIDS-associated disorders.

Role of apoptosis in HIV disease pathogenesis

After approximately one and a half decades of intensive studies, the exact mechanisms to explain HIV-mediated cytopathicity are still enigmatic and need closer scrutiny. There has been a dichotomy between virological and immunological viewpoints in understanding HIV-mediated cytopathicity, the former emphasizing a killing of infected cells by HIV-1 and the latter emphasizing indirect mechanisms wherein HIV or its soluble component(s) alter CD4 T-cell function and induce susceptibility to apoptosis. Accumulating evidence points to the notion that apoptosis might be a major contributor to the depletion of CD4 T-cells in HIV infection. This review summarizes current information about the regulatory mechanisms of T-cell apoptosis and the role of apoptosis in HIV pathogenesis with the goal of providing an integrated view of HIV cytopathicity.

Rate of detection of human herpesvirus-6 at different stages of HIV infection

In a cross-sectional study, human herpesvirus-6 (HHV-6) infection was analysed by means of polymerase chain reaction in peripheral blood mononuclear cells (PBMCs) and saliva from 125 HIV-seropositive subjects and 29 HIV-seronegative controls. HHV-6 was detected in saliva significantly more frequently in HIV-seronegative subjects than in HIV-seropositive subjects (p = 0.023), with no significant difference between HIV-seropositive subgroups. The HIV proviral copy number in PBMCs differed significantly according to HIV subgroup, as expected, but did not differ according to either the presence of HHV-6 or the number of HHV-6 copies in PBMCs. All the HHV-6 identified were variant B except for one variant A strain detected in saliva from a healthy subject. These results do not support the hypothesis that there is synergistic activation of HHV-6 infection in the course of HIV infection.

Feline immunodeficiency virus replicates in salivary gland ductular epithelium during the initial phase of infection

Feline immunodeficiency virus (FIV) antigen was detected by immunochemistry in salivary glands of cats experimentally inoculated with West Australian isolate T91. Six cats were inoculated subcutaneously with 1.0 ml of tissue culture supernatant fluid from a feline T-lymphoblastoid cell line (MYA-1) infected with T91. FIV antigens were detected in the interlobular ducts of the salivary gland of cats infected with FIV 2, 4 and 6 weeks previously. FIV antigen was not detected in the salivary glands of three FIV negative cats and one naturally infected cat. Further, FIV antigen was located only in interlobular duct epithelial cells. The distribution of FIV in the interlobular ducts confirms the important role of salivary glands as a major reservoir of FIV in the early phase of infection and strengthens suggestions that the salivary route is an important mode of transmission of FIV.

Surgical treatment of lung cancer in patients with human immunodeficiency virus

BACKGROUND

Since January 1986, more than 20 patients have been seen at the University of Miami/Jackson Memorial Medical Center and the Miami Veterans Administration Medical Center with concurrent human immunodeficiency virus infection and bronchogenic carcinoma. Four of these patients were treated surgically with curative intent.

METHODS

The histories, records, operative reports, and pathology reports of the 4 patients were reviewed.

RESULTS

The 4 surgically treated patients had stage I T1 N0 M0 lung cancer. Three patients had T4 cell counts of less than 200/microL and were managed by lobectomy. These patients died 5, 3 1/2, and 5 months postoperatively. More recently, a fourth patient had a T4 cell count of 963/microL and was treated with wedge resection. He is currently alive 12 months postoperatively.

CONCLUSIONS

It is concluded that surgically treated patients with lung cancer, human immunodeficiency virus infection, and T4 cell counts lower than 200/microL have high mortality and morbidity. Although it may be best to base surgical intervention on the stage of the patient's human immunodeficiency virus infection, further analysis is essential to determine which subgroup of human immunodeficiency virus-positive patients, if any, would benefit from surgical treatment of lung cancer.

A controlled trial of zidovudine in primary human immunodeficiency virus infection

BACKGROUND

It is possible that antiretroviral treatment given early during primary infection with the human immunodeficiency virus (HIV) may reduce acute symptoms, help preserve immune function, and improve the long-term prognosis.

METHODS

To assess the effect of early antiviral treatment, we conducted a multicenter, double-blind, placebo-controlled trial in which 77 patients with primary HIV infection were randomly assigned to receive either zidovudine (250 mg twice daily; n = 39) or placebo (n = 38) for six months.

RESULTS

The mean time from the onset of symptoms until enrollment in the study was 25.1 days. Among the 43 patients who were still symptomatic at the time of enrollment, there was no appreciable difference in the mean (+/- SE) duration of the retroviral syndrome between the zidovudine group (15.0 +/- 4.1 days) and the placebo group (15.8 +/- 3.6 days). During a mean follow-up period of 15 months, minor opportunistic infections developed in eight patients: oral candidiasis in four, herpes zoster in two, and oral hairy leukoplakia in two. Disease progression was significantly less frequent in the zidovudine group (one opportunistic infection) than in the placebo group (seven opportunistic infections; P = 0.009 by the log-rank test). After adjustment for the base-line CD4 cell count, the patients treated with zidovudine had an average gain of 8.9 CD4 cells per cubic millimeter per month (95 percent confidence interval, -1.4 to 19.1) during the first six months of the study, whereas those receiving placebo had an average loss of 12.0 CD4 cells per cubic millimeter per month (95 percent confidence interval, 5.2 to 18.7), for a between-group difference of 20.9 CD4 cells per cubic millimeter per month (95 percent confidence interval, 8.5 to 33.2; P = 0.001).

CONCLUSIONS

Antiretroviral therapy administered during primary HIV infection may improve the subsequent clinical course and increase the CD4 cell count.

Study of LDL and acetylated LDL endocytosis by mononuclear cells in HIV infection

Activated lymphocytes have a high level of low density lipoprotein (LDL) uptake as compared to resting lymphocytes, whereas scavenger receptors for acetylated LDL (Ac-LDL) are expressed on limited number of immune cells, i.e., monocytes/macrophages. The endocytosis of LDL and Ac-LDL by mononuclear cells was studied during in vitro and in vivo HIV infection, in order to use LDL and Ac-LDL as carriers of antiviral and/or immunomodulatory drugs towards lymphocytes and monocytes. The uptake of LDL and Ac-LDL was analyzed by cytofluorimetry. LDL endocytosis in PHA/IL2-activated lymphocytes was higher than in resting lymphocytes. In vitro HIV infection of PHA/IL2-activated lymphocytes did not alter the high LDL endocytosis in lymphocytes. CD4+ and CD8+ cells. In a group of 12 symptomatic patients there was no alteration of LDL endocytosis in lymphocytes, CD4 and CD8 lymphocytes. In another group of 23 individuals, the Ac-LDL endocytosis mediated by CD14+ monocytes was unaltered in asymptomatic patients (n = 6) and in some symptomatic patients (n = 6, CD14+ cells > 100/mm3). On the contrary, in other symptomatic patients (n = 11, CD14+ cells < 100/mm3), the number of Ac-LDL+ CD14+ cells decreased, whereas their efficiency of Ac-LDL endocytosis increased as compared to those of other HIV+ patients. In conclusion, the use of lipoproteins as carriers to increase the drug delivery to CD4+ lymphocytes and to CD14+ monocytes can be envisaged, since: (i) the LDL endocytosis was not impaired in CD4 lymphocytes of HIV+ patients, and (ii) the Ac-LDL uptake by monocytes was altered only in some patients of stage IV.

Genetic background and environment contribute synergistically to the onset of autoimmune diseases

Autoimmune diseases result from the breakdown of "self" tolerance. Environmental factors appear to be responsible for triggering this errant immune response, directed against self-tissue determinants, only when a susceptible genetic background is present in an individual. Autoimmune diseases, normally characterized by their association with certain HLA alleles, also share other features: the presence of autoantibodies, autoreactive T lymphocytes, and an intermittent clinical course of exacerbations and remissions. In cases of organ-specific diseases, as well as in cases of multi-system autoimmune diseases, viruses are increasingly implicated as such environmental triggers. Current molecular biology techniques have permitted a fine dissection of the genetic background of susceptible individuals and have enabled a more complete characterization of the immunocompetent cells involved in this autoaggression. Molecular approaches will soon allow us to pinpoint the characteristics of the environmental stimuli, so that protective strategies could be formulated to spare susceptible individuals from their ill effects.

Pediatric AIDS

An estimated 1 million children worldwide have AIDS. Pediatricians should be aware of this disease and its many facets. This article provides information on the etiology and pathogenesis of AIDS in children, as well as its manifestations on the body. Prevention and clinical management are also reviewed.

Increased serum concentration of soluble HLA-DR antigens in HIV infection and following transplantation

HLA class I and class II antigens circulate in serum as soluble molecules. Increased concentrations of soluble HLA class I molecules have been demonstrated in viral diseases, in rejection episodes following organ transplantation and in graft versus host disease. To explore the possibility of a variation of the serum concentrations of soluble HLA class II molecules in the same pathologic conditions we developed a double determinant immune assay that detects whole soluble HLA-DR molecules (sHLA-DR). The mean level of sHLA-DR antigens in sera from 23 healthy individuals was 0.64 +/- 0.72 microgram/ml. Elevated serum concentrations of sHLA-DR molecules were detected in sera from HIV infected patients in CDC2/3 and in CDC4 C1 stages (2.0 +/- 1.7 micrograms/ml and 4.6 +/- 1.7 micrograms/ml, respectively), in sera from patients affected by acute rejection after liver transplantation (5.3 +/- 3.7 micrograms/ml) and in sera from patients affected by severe acute graft versus host disease following bone marrow transplantation (8.8 +/- 3.1 micrograms/ml). The increase of sHLA-DR molecules in these sera significantly correlated with the elevation of soluble HLA class I antigens (P = 0.0004). The reported data suggest that both soluble HLA class I and class II molecules serum levels increase during viral infections and strong immune reactions and could suggest the involvement of these molecules in immunoregulation.

Defective accessory genes in a human immunodeficiency virus type 1-infected long-term survivor lacking recoverable virus

We have been studying a patient who acquired human immunodeficiency virus (HIV) infection via a blood transfusion 13 years ago. She has remained asymptomatic since that time. The blood donor and two other recipients have all died of AIDS. Although this patient has shown persistently strong seroreactivity to HIV type 1 (HIV-1) antigens by Western blot (immunoblot), she has been continually HIV culture negative in results from multiple laboratories over the last 6 years and has a very low viral burden. Her CD4+ T-cell count has fluctuated around a mean of 399 cells per microliters, with little change in lymphocyte subset percentages. Strong cellular immune responses to HIV-1 epitopes by this patient have been demonstrated. We now report the results of an intensive molecular genetic analysis of the HIV-1 proviral quasispecies from this patient sampled over 5 years. Long terminal repeat region sequences supported the argument for normal basal and Tat-mediated promoter activities. Sequential sequencing of the nef gene revealed a low frequency (8.3%) of defective genes and a striking lack of sequence evolution. Functional analysis of predominant nef genes by both a cell surface CD4 downregulation and a viral infectivity complementation assay showed wild-type function. In contrast, sequential analysis of an amplicon containing the vif, vpr, vpu, tat1, and rev1 genes revealed the presence of inactivating mutations in 64% of the clones. These data suggest that this patient, initially infected with a virulent swarm of HIV-1, is presently infected with a more-attenuated viral quasispecies as a result of effective host immunity.

Failure of T-cell homeostasis preceding AIDS in HIV-1 infection. The Multicenter AIDS Cohort Study

We and others have postulated that a constant number of T lymphocytes is normally maintained without regard to CD4+ or CD8+ phenotype ('blind' T-cell homeostasis). Here we confirm essentially constant T-cell levels (despite marked decline in CD4+ T cells and increase in CD8+ T cells) in homosexual men with incident human immunodeficiency virus, type 1 (HIV-1), infection who remained free of acquired immunodeficiency syndrome (AIDS) for up to eight years after seroconversion. In contrast, seroconverters who developed AIDS exhibited rapidly declining T cells (both CD4+ and CD8+) for approximately two years before AIDS, independent of the time between seroconversion and AIDS, suggesting that homeostasis failure is an important landmark in HIV disease progression. Given the high rate of T-cell turnover in HIV-1 infection, blind T-cell homeostasis may contribute to HIV pathogenesis through a CD8+ T lymphocytosis that interferes with regeneration of lost CD4+ T cells.

Levels of the circulating cell adhesion molecule E-selectin and disease progression in HIV infection

The levels of soluble form of E-Selectin (sEs), or endothelial-leukocyte adhesion molecule-1, were measured in 96 sera derived from 72 HIV-infected patients at different stages of the disease, 60 healthy blood donors, and 50 HIV-negative patients with infections, using a quantitative ELISA. Levels of sEs in HIV-infected individuals without AIDS, according to the 1993 classification system of the Centers for Disease Control, were higher than normal (mean +/- SEM 48 +/- 4 versus 35 +/- 3 ng/ml, p = 0.003). Patients with established AIDS, who were afebrile and had no evidence of acute concurrent infection, had even higher sEs serum levels (70 +/- 9 ng/ml, p = 0.009, compared to those without AIDS). A significant increase in clinical category disease progression was present. Individual concentrations of sEs correlated directly with levels of soluble intercellular adhesion molecule-1 (p < 0.00001) and IL-2 receptor (p = 0.001), but not with CD4+ T-cell counts. Zidovudine treatment was not associated with changes in sEs serum levels. Elevated sEs levels were also found in HIV-seronegative patients with other bacterial and protozoal infections. Since sEs is a biologically active molecule, further studies should investigate the pathogenetic significance of circulating sEs in HIV-related disease progression, and assess the prognostic value of sEs determination for these patients.

Frequency of provirus-bearing CD4+ cells in HIV type 1 infection correlates with extent of in vitro apoptosis of CD8+ but not of CD4+ cells

Lymphocytes from HIV-1-infected subjects undergo massive apoptosis when cultured in vitro, and this phenomenon might reflect pathogenetic mechanisms leading to immune dysfunction in vivo. However, (1) lymphocyte death is not restricted to CD4+ cells but seems to involve predominantly CD8+ cells, and (2) the same phenomenon occurs in other viral infections. Furthermore, it is not known whether a relationship exists between the HIV-1 burden and this type of cell death. In this work we sought to determine whether the HIV-1 provirus load correlates with the propensity to apoptosis of CD4+ and CD8+ cells. We studied 10 HIV-1-infected patients with CD4+ cell counts above 500/mm3 and free of concomitant infections. We correlated the frequency of HIV-1-infected CD4+ cells with the extent of culture-induced apoptosis as well as with the phenotype of the apoptotic lymphocytes. We found that the magnitude of apoptosis correlated with the frequency of HIV-1-infected CD4+ cells (p = 0.0007), and that increasing viral load and apoptosis were associated with a shift to the selective death of CD8+ cells. Our data support the view that, in addition to CD4+ cell killing, another immunopathogenic effect of HIV might be that of priming CD8+ cells to apoptosis. In vivo, this could eventually lead to the exhaustion of the cytotoxic T cell compartment.

[Paracoccidioidomycosis in a patient with human immunodeficiency virus infection. A necropsy case]

This is a case report of the association of Paracoccidioidomycosis and Acquired Immunodeficiency Syndrome (AIDS) occurring in a 43-year old male. This is, to the best of our knowledge, the first detailed pathological account of that association. Also discussed are the low rates of that association, its natural history and treatment results. It is emphasised the importance of the associations of AIDS and tropical infectious diseases in this country.

Early appearance of antibodies to simian immunodeficiency virus in saliva and serum of infected macaques

Simian immunodeficiency virus (SIV) infection in macaques is an important animal model for human immunodeficiency virus infection in humans. This study evaluated the temporal development of antibodies to SIV in the parotid saliva of macaques inoculated with the virus and compared these findings with the development of antibodies to SIV in the animals' sera. Three animals (ages, 14, 18, and 18 years) were inoculated with the macrophagetropic strain SIVmac239. Prior to inoculation and at consecutive weekly intervals during a four-week period following the initial virus inoculations, parotid saliva and serum were collected from each animal. A fourth animal (age, 9 years) served as a negative control, and the fifth and sixth animals (ages, 2 and 22 years) served as positive controls (6 and 18 months postinoculation, respectively) with SIVmac239. Saliva and serum samples were reacted against SIV antigen in Western blots (immunoblots) prepared in the standard fashion to determine the presence of antibodies. The reactions of these antigen-antibody complexes with biotinylated anti-human immunoglobulin A (IgA), IgM, and IgG and biotinylated anti-human secretory component (SC) determined the class of antibody present or the presence of SC in the original parotid saliva or serum samples. In infected animals, the IgM to SIV was detectable in serum and saliva at 13 days, and antiviral IgA and IgG in serum and saliva were detectable at 20 to 27 days postinoculation. The antibody to SC reacted to saliva from only two animals at 20 and 27 days, and long-term positive controls were positive for SC in saliva, indicating that either secretory IgA or secretory IgM was present in these samples. Antibodies to SIVmac239 antigens have therefore been detected in saliva as early as 13 days postinfection. Saliva may be as useful as serum as a diagnostic specimen and/or disease-monitoring method in this important animal model.

Detection of CD4+ T cells harboring human immunodeficiency virus type 1 DNA by flow cytometry using simultaneous immunophenotyping and PCR-driven in situ hybridization: evidence of epitope masking of the CD4 cell surface molecule in vivo

Human immunodeficiency virus type 1 (HIV-1) infection of T cells and cells of the monocyte/macrophage lineage requires a specific interaction between the CD4 antigen expressed on the cell surface and the HIV-1 external envelope glycoprotein (gp120). To study the association between HIV-1 infection and modulation of cell surface expression of the CD4 molecule in vivo, we examined the CD4+ T cells harboring proviral DNA obtained from HIV-1-infected individuals who had received no antiretroviral therapy for at least 90 days. Simultaneous immunophenotyping of CD4 cell surface expression and PCR-driven in situ hybridization for HIV-1 DNA were used to resolve the CD4+ T cells into distinct populations predicted upon the presence or absence of proviral DNA. Among the HIV-1-infected study subjects, the percentage of CD4+ T cells harboring proviral DNA ranged from 17.3 to 55.5%, with a mean of 40.5%. Cell surface fluorescent staining with anti-CD4 antibody directed against a non-gp120 binding site-related epitope (L120) or a conformation-dependent epitope of the gp120 binding site (Leu 3A) demonstrated either an equivalent or a 1.5- to 3-fold-lower cell surface staining intensity for the HIV-1 DNA-positive subpopulation relative to the HIV-1 DNA-negative subpopulation, respectively. These data suggest that masking or alteration of specific epitopes on the CD4 molecule occurs after viral infection.

Infection prevention strategies for children with cancer and AIDS: contrasting dilemmas

Infectious complications represent significant challenges for children with cancer and those infected with HIV. Although both have similarities in the disease- and treatment-related alterations in host defences, there are significant differences that can have an impact on the approach to treatment and prevention of the dominant infectious complications. An important difference is that children with cancer readily recover from neutropenia. Thus, the immune deficits are interspersed with intervals of immunological recovery. On the other hand, children with HIV infection do not appreciably recover from the progressive, immunological changes associated with the underlying HIV infection. The loss of cellular and humoral immunity is generally not reversible, and thus the risk of infection only increases over time. Bacteria constitute the predominant pathogen for paediatric cancer patients but invasive mycoses, viruses and parasitic infections are emerging as important pathogens. In paediatric cancer patients, strategies have been directed at altering or suppressing the endogenous colonization patterns of pathogenic bacteria. The success of this approach has been limited and at the expense of selecting for antibiotic-resistant bacterial infections. Children with HIV infection are at risk of developing a wide spectrum of pathogens. Strategies for infection prevention in the HIV setting have been directed at specific organisms, generally using more specific antimicrobial agents and with greater success.

Selective mechanisms utilized by persistent and oncogenic viruses to interfere with antigen processing and presentation

Cell-mediated immunity is effective against cells harboring active virus replication, and is critical for the elimination of ongoing infections, regression of virus-associated tumors, and reducing or preventing the reactivation of persistent viruses. The capacity of persistent and oncogenic viruses to maintain a long-term relationship with their host presupposes viral mechanisms for circumventing antiviral defenses. By suppressing the expression of molecules associated with antigen processing and presentation, viruses abrogate the major immune mechanism that deals with the elimination of infected and tumor cells. This is accomplished either by transcriptional downregulation of genes encoding class I MHC antigens, peptide transporter molecules, and the proteasome-associated LMP subunits, or by interfering with transport of class I molecules to the cell surface. In some cases viruses shut off the expression of most viral proteins during latency or express mainly nonimmunogenic or antagonistic peptide epitopes. This review describes selective mechanisms utilized by viruses for interference with antigen processing and presentation, and addresses their significance for in vivo viral persistence and tumor progression.

T helper cell dichotomy to Candida albicans: implications for pathology, therapy, and vaccine design

Acquired immunity to Candida albicans is believed to prevent mucosal colonization of adult immunocompetent individuals from progressing to symptomatic infection. Resistance to disease appears to correlate with the detection of delayed-type hypersensitivity responses in vivo and a T helper type 1 (Th1) cytokine secretion profile in vitro. Cellular immunodeficiency, particularly HIV infection, greatly increases the risk of mucosal infection, confirming that CD(4+)-cell-directed immunity is effective locally in controlling infectivity of the yeast. While Th1-type CD4+ cell activation resulting in phagocyte-dependent immunity clearly represents an important mechanism of anticandidal resistance, clinical observations suggest that Th2-type CD4+ cell reactivity may be triggered by Candida antigens in several disease states, including symptomatic infections and immunopathology. This may imply that a Th1-type pattern of reactivity characterizes the saprophytic yeast carriage and resistance to disease by healthy humans, whereas Th2-type responses would be mostly associated with pathology. Moreover, Candida-specific T helper responses, namely humoral and cell-mediated immunity, appear to be reciprocally regulated, as typically occurs in experimental models of parasitic and retroviral infection, where the Th1/Th2 paradigm of acquired immunity has been best characterized. Recent studies, besides providing direct evidence for the occurrence of cross-regulatory Th1 and Th2 responses in mice with candidiasis, emphasize the potential of cytokine/anticytokine therapy for recruiting Candida-specific responses toward protective, Th1-type CD4+ cell reactivity. At the same time, these studies call attention to the possible consequences of C. albicans infection for immunopathology, allergy, and coinfection.

Review article: manipulation of cell death--the development of novel strategies for the treatment of gastrointestinal disease

The mechanisms underlying cell death are reviewed in order to propose new targets for the therapy of gastrointestinal disease. Necrosis is a set of precise biochemical and cellular lesions which culminate in cell destruction. A number of potential targets for drug therapy are discussed which will inhibit necrosis, including preservation of cellular ATP by inhibition of poly(ADP-ribose) polymerase. Such therapies may be useful either as adjuncts to other therapeutic modalities such as immunosuppressive agents for the treatment of inflammatory conditions or on their own for organ preservation prior to organ transplantation. Either excessive apoptosis or failure of apoptosis plays an important role in a variety of gastrointestinal diseases. Failure of apoptosis is of particular importance in the development of colorectal cancer. Mutations or deletions of p53, bcl-2 and myc prevents the appropriate deletion of malignant cells and causes resistance to anti-cancer drugs which act by the induction of apoptosis. Correction of these genetic defects or replacement of their function is a major strategy in cancer prevention and therapy. It is concluded that manipulation of cell death processes is an important new area for gastrointestinal research.