Anti-HIV effects of chloroquine: mechanisms of inhibition and spectrum of activity.

OBJECTIVE: To investigate the mechanisms and spectrum of the anti-HIV activity of chloroquine. DESIGN AND METHODS: MT-4 cells or peripheral blood mononuclear cells were infected with X4, R5 or R5/X4 HIV-1 strains from clades A-E and HIV-2. The cells were then treated with clinically relevant and achievable chloroquine concentrations (i.e. 0-12.5 microM), so as to determine the EC50. The effects of chloroquine on reverse transcription and integration were tested using a replication-defective reporter HIV-1 construct (pRRL.sin.hPGK.GFP). The effects of the drug on the viral envelope were assessed by syncytium assays and immunoprecipitation, using antibodies to different epitopes of gp120. RESULTS: In de-novo infected MT-4 cells, chloroquine selectively inhibited HIV-1 IIIB replication but not pRRL.sin.hPGK.GFP. In chronically HIV-1-infected H9 IIIB cells, chloroquine decreased the infectivity of the newly produced virus and the ability of these cells to form syncytia in co-culture with MT-2 cells. These effects were associated with structural changes in the gp120 glycoprotein, such as a reduction of reactivity with antibodies directed against the glycosylated 2G12 epitope. Although affecting a variable target such as gp120, chloroquine was capable of inhibiting X4, R5 and R5/X4 primary HIV-1 isolates from subtypes A, B, C, D, E and HIV-2. CONCLUSION: At clinically achievable concentrations chloroquine inhibits HIV-1 post-integrationally by affecting newly produced viral envelope glycoproteins, and the drug has broad-spectrum anti-HIV-1 and HIV-2 activity.

Regulation of class II expression in monocytic cells after HIV-1 infection.

Human macrophage hybridoma cells were used to study HLA-DR expression after HIV-1 infection. HLA-DR surface expression was lost 2 wk after infection that was associated with decreased mRNA transcription. Transfecting HLA-DR-alpha and HLA-DR-beta cDNA driven by a nonphysiological CMV promoter restored expression, suggesting that regulatory DNA-binding proteins may be affected by HIV-1 infection. There was no protein binding to conserved class II DNA elements (W/Z/S box, X-1 and X-2 boxes, and Y box) in a HIV-1-infected human macrophage hybridoma cell line, 43(HIV), and in primary monocytes that lost HLA-DR expression after HIV-1(BaL) infection. PCR analysis of the HIV-1-infected cells that lost HLA-DR expression revealed mRNA for W/Z/S (RFX-5), X-1 (RFX-5), X-2 (hX-2BP), and one Y box DNA-binding protein (NF-YB), and CIITA, a non-DNA-binding protein necessary for class II transcription. There was no mRNA for the Y box-binding protein, NF-YA. However, HLA-DR expression could be restored by transfection with NF-YA driven by a CMV promoter, although HLA-DR failed to localize in either the late endosomes, lysosomes, or acidic compartments. This was associated with a loss of class II-associated invariant chain peptide and leupeptin-induced protein in the 43(HIV) cells. To address this further, non-HIV-1-infected 43 cells were infected with vaccinia virus containing HIV-1 gag, nef, pol, and env proteins. HLA-DR failed to localize in neither the late endosomes, lysosomes, or acidic compartments in the vaccinia-infected cells containing HIV-1 env protein. HIV-1 appears to have multiple effects on class II expression in monocytic cells that may contribute to the immune defects seen in HIV-1-infected patients.

The additive in vitro anti-HIV-1 effect of chloroquine, when combined with zidovudine and hydroxyurea.

The 4-aminoquinoline chloroquine and its analogue hydroxychloroquine are endowed with anti-HIV-1 activity both in vitro and in vivo. We previously reported that the addition of CQ (chloroquine) to the combination of HU (hydroxyurea) and ddI (didanosine) provides additive anti-HIV-1 activity. We here extended this in vitro investigation by studying whether the addition of CQ also resulted in additive anti-HIV-1 activity when combined with HU plus AZT (zidovudine). The same effect was found, whether CQ was added to HU plus AZT or to HU plus ddI, in recently infected H-9 and U-937 cells or primary T cells and monocytes, as well as in immunologically or oxidatively stimulated ACH-2 and U-1 cells. At concentrations where CQ exerts its anti-HIV-1 effect in combination with the other drugs, CQ addition does not result in either cell toxicity or apoptosis.

Oral tolerance to protein antigens.

Oral tolerance is an active non-response to antigens delivered via the oral route. Mechanisms governing tolerance induction have been well characterized in mouse. Similar studies in man are lacking, although there is evidence that tolerance can be induced. In disease states, tolerance is altered and this may account for the presence of mucosal inflammation. In food hypersensitivity there is evidence that allergens may be handled differently and this may play a role in disease expression.

The anti-HIV-1 activity of chloroquine.

BACKGROUND: there is a dramatic need for drugs with anti-HIV-1 activity that are affordable for resource-poor countries. Chloroquine (CQ) is one such drug. OBJECTIVES: to review the data indicating that CQ has anti-HIV-1 activity. RESULTS: chloroquine (CQ) and its derivative hydroxychloroquine (HCQ) are endowed with a broad anti-HIV-1 activity inhibiting X4, R5, and X4/R5 stains in lymphocytic and monocytic cells. Interestingly, CQ is capable of inhibiting HIV-1 replication at concentrations within the range reported in plasma of individuals chronically treated with doses of the drug which have well-known and limited toxicity. These effects have been confirmed in vivo in two clinical trials. The principal mechanism of HIV-1 inhibition by CQ seems to be an effect on gp120 on a post-transcriptional level. Because CQ and HCQ appear to have a novel site of action (i.e. post-transcriptional inhibition of gp120), these drugs may be particularly useful in combination with other anti-retroviral agents (e.g. ZDV, ddI and HU). CONCLUSION: combining these drugs with other anti-HIV-1 agents, especially HU and ddI, may be an interesting option for the treatment for HIV-1 infected individuals in the developing world.

The potential place of chloroquine in the treatment of HIV-1-infected patients.

BACKGROUND: Chloroquine has been reported to be endowed with anti-HIV-1 activity. We previously found its anti-HIV-1 activity to be additive to that of of the hydroxyurea plus didanosine combination. OBJECTIVES: Here we wish to present reported data on chloroquine's effects other than its antiretroviral activity, that may be of benefit in the therapy of HIV-1-infected individuals. RESULTS: (1) Chloroquine exerts an inhibitory effect on several AIDS-opportunistic pathogens, at least in vitro and, in some cases, in murine infections. (2) The drug exerts an inhibitory effect on the synthesis of several pro-inflammatory cytokines that may play a pathogenic role in the progression of HIV infection. (3) The drug has the potential to restrict tissular iron accumulation that may play a negative role in HIV infection. (4) The drug has practical advantages, as it is widely distributed, inexpensive and not stigmatizing. (5) We hypothesized that the drug, if given to HIV-positive breast-feeding mothers, may be of potential benefit in decreasing the rate of mother-to-child transmission of HIV-1. CONCLUSION: in view of the above-given data, combination therapy with chloroquine warrants clinical studies in HIV-1-infected patients, mainly in the setting of resource-poor countries.

Antigen uptake and trafficking in human intestinal epithelial cells.

Primary intestinal epithelial cells, human colonic adenocarcinoma cell lines (DLD-1, Caco-2, and HT-29), and monocytes were used as model systems to study antigen uptake, antigen-presenting cell properties, as well as the kinetics of antigen uptake in intestinal epithelial cells (IEC). Intracellular staining of fluoresceinated tetanus toxoid was not evident in the IEC until after 30 min of incubation at 37 degrees C, whereas in monocytes intracellular punctate staining of fluoresceinated tetanus toxoid was evident after 5 mins. In polarized Caco-2 cells antigen could be internalized at both the apical and basolateral surfaces with polarized transport. When analyzed by electron microscopy, gold-labeled tetanus toxoid was internalized and found within endosomes and multivesicular bodies, but not within the lysosomal compartments by 60 min. By 2 hrs, gold-labeled tetanus toxoid was evident in the secondary lysosomes. These results demonstrate that tetanus toxoid follows an endocytic pathway in intestinal epithelial cells and that the kinetics of antigen uptake is slower than that of conventional antigen-presenting cells.

Factors affecting antigen uptake by human intestinal epithelial cell lines.

We assessed the role of size, solubility, and prophagocytic cytokines interferon-gamma (IFN-gamma), and granulocyte-macrophage colony stimulatory factor (GM-CSF) in antigen uptake and kinetics by intestinal epithelial cells using keyhole limpet hemocyanin and ovalbumin. Both fluoresceinated keyhole limpet hemocyanin (3000-7500 kDa) and fluoresceinated ovalbumin (45 kDa) were internalized by human colonic epithelial cell lines, with kinetics similar to those of fluoresceinated tetanus toxoid, and there was decreased uptake of insoluble immune complexes and no enhancement in the uptake of soluble immune complexes. In addition, neither IFN-gamma nor GM-CSF altered the kinetics of uptake nor enhanced antigen internalization by the intestinal epithelial cell lines. These data suggest that regardless of the size of the soluble antigen, the presence of prophagocytic cytokines, or the formation of soluble immune complexes, fluid phase endocytosis of antigen by intestinal epithelial cells appears to be a relatively stable process.

The effect of viruses on the ability to present antigens via the major histocompatibility complex.

We describe viral pathogens that cause significant human disease by their ability to interfere with the expression of major histocompatibility complex class I and II molecules. Herpesviruses and papillomaviruses encode gene products that interfere with the class I pathway of antigen processing and/or peptide translocation. Adenoviruses encode unique gene products that interfere with transport of class I molecules. Influenza virus, measles virus, and HIV interfere with the class II pathway by either suppressing the production of class II molecules or impeding antigen trafficking. Cytomegalovirus interferes with both class I and class II pathways. Better understanding of these mechanisms may lead to further insight into the pathogenesis of viral infections and allow for improved treatments.

Chloroquine exerts an additive in vitro anti-HIV type 1 effect when associated with didanosine and hydroxyurea.

Several groups, including ours, have reported that chloroquine (CQ) or its analog hydroxychloroquine has anti-HIV-1 activity both in vitro and in vivo. We studied in vitro whether the addition of CQ to the combination of hydroxyurea (HU) plus didanosine (ddI) had an additive effect in inhibiting the replication of HIV-1. Therefore both the H-9 T lymphocytic cell line and the U-937 promonocytic cell line as well as primary T cells and monocytes were infected with HIV-1 and then treated with HU at 0.2 mM and ddI at 1 microM and varying concentrations of CQ. Addition of CQ resulted in an additional inhibition of HIV-1 replication, as assessed by reverse transcriptase (RT) activity, with a CQ EC50 of 0.4-0.9 microM for the cell lines and of 0.2-0.9 microM for the primary cells. Similarly, addition of CQ further inhibited HIV-1 replication in U-1 cells stimulated either with LPS or H2O2 and in ACH-2 cells stimulated either with PMA or H2O2, with CQ EC50 values of 0.1 and 1 microM, respectively. Under the experimental conditions used, CQ induced neither toxicity nor apoptosis in the H-9 and U-937 cells. This in vitro additive anti-HIV-1 activity of CQ, in combination with HU + ddI, supports the idea that this triple regimen should be studied in clinical trials. It may become of particular interest to HIV-1-infected individuals from the developing world, in view of the low cost of both CQ and HU.

Antigen trafficking and accessory cell function in respiratory epithelial cells.

We investigated accessory cell function, antigen (Ag) trafficking, and uptake of immune complexes in isolated nasal epithelial cells (NEC) and airway epithelial cells (AEC), as well as in the two respiratory epithelial cell lines A549 and BEAS-2B. The NEC and AEC were capable of supporting Ag-specific as well as phytohemagglutinin-induced and anti-CD3 antibody-induced T-cell proliferation. We colocalized fluorescein isothiocyanate (FITC)-labeled Ags with human leukocyte antigen (HLA)-DR in A549 and BEAS-2B, utilizing laser confocal microscopy. Respiratory epithelial cells stimulated and unstimulated with interferon (IFN)-gamma were pulsed with FITC-labeled Ags for varying periods and evaluated for their ability to internalize Ag. In the unstimulated cells, intracellular punctate staining was evident at 60 min and persisted up to 120 min. In the IFN-gamma-stimulated cells (100 U/ml for 48 h), uptake occurred at 30 min, was maximal at 60 min, and diminished at 120 min. We conducted kinetic studies in the A549 and BEAS-2B cells, utilizing electron microscopy with colloidal gold-conjugated Ags (Au-OVA). At 15 min, Au-OVA was evident in the early compartments resembling the compartment of uncoupling of receptor and ligand. At 30 min, multivesicular bodies were labeled with Au-OVA, and by 60 min Au-OVA was present in the primary and secondary lysosomes. The FITC-labeled Ags colocalized with an early endosomal marker (anti-cathepsin D), a late endosomal marker (M6PR), a lysosomal marker (CD63), and with 3-(2, 4-dinitroanilino)-3'-aminomethyldipropylamine, a marker of acidic vesicles. The BEAS-2B and A549 cells, and NEC and AEC, expressed surface Fcgamma receptor and internalized IgG immune complexes. The NEC and AEC also expressed the costimulatory molecules CD80 and CD86 as determined with flow cytometry, the reverse transcription-polymerase chain reaction for RNA, and immunohistochemistry, and T-cell proliferation could be blocked by treating NEC and AEC with anti-CD80 and anti-CD86 antibodies. Our findings suggest that respiratory epithelial cells may have a role in local Ag presentation.

Correlation of clinical parameters and immunological function with human immunodeficiency virus plasma viremia in children.

Studies of immune function in human immunodeficiency virus (HIV)-infected children are important, because functional abnormalities can precede CD4+ T-cell loss and are associated with the development of opportunistic and bacterial infections. We sought to correlate clinical parameters and immunological function with HIV RNA plasma levels in 20 children. HIV RNA levels were measured by a polymerase chain reaction assay. We analyzed T-cell responses to mitogens (phytohemagglutinin, concanavalin A, and pokeweed [PWM]) and antigens (tetanus toxoid and Candida albicans); T-cell suppressor activity; and humoral immunity to Haemophilus influenzae, hepatitis B, tetanus, and diphtheria vaccines. The median age of the children was 6 years. Eight children had HIV RNA levels less than 200 to 9621 copies per milliliter (group I). Four children had 37,970 to 82,630 copies per milliliter (group II). Eight children had 102,100 to 191,200 copies per milliliter (group III). There were no differences in the HIV-related complications between group I and II children. Group I/II children had significantly higher CD4+ T-cell counts (P = 0.02), less symptomatic HIV disease (P = 0.005), and more detectable protective vaccine immunity (P = 0.014) compared with group III children. Responses to mitogens were conserved in most children. Group I children tended to have higher responses to tetanus toxoid than group II children and significantly higher responses than group III children (P = 0.01). Group I had significantly higher responses to C. albicans than groups II (P = 0.016) and III (P = 0.001). Group I/II children tended to have lower suppressor activity compared with group III children (median, 0 vs 64%). We demonstrated that humoral and cellular immune dysfunction exists at all stages of disease in HIV-infected children but was most severe in children with greater than or equal to 100,000 HIV RNA copies per milliliter. Function was the most intact in children with less than 10,000 copies per milliliter.

Desensitization to 5-fluorouracil.

Anaphylactic reactions to 5-fluorouracil (5-FU) are uncommon. We report a 40-year-old female with adenocarcinoma of the ovary who had two reactions immediately after being infused with 5-FU. The second reaction occurred despite prophylaxis with steroids and antihistamines. The patient was positive to 5-FU on puncture skin testing even though there was no previous exposure to the drug. We successfully desensitized her to 5-FU using a continuous intravenous protocol with sequential increments in the fusion rates and drug concentrations. This desensitization method may be useful to manage systemic reactions to 5-FU and other drugs.

A multicenter, randomized, double-blind, placebo-controlled trial of high-dose intravenous immunoglobulin for oral corticosteroid-dependent asthma.

To determine the efficacy of high doses of intravenous gammaglobulin (IVIG) for the treatment of severe, steroid-dependent asthma in patients between 6 and 68 years of age, a randomized, double-blind, placebo-controlled multicenter clinical trial was conducted in private and university hospitals in the United States. Patients were randomized to one of three treatment arms: 2 g IVIG/kg/month (16 patients); 1 g IVIG/kg/month (9 patients); or 2 g iv albumin (placebo)/kg/month (15 patients). The treatment consisted of seven monthly infusions followed by a posttreatment observation period. The primary outcome measurement was mean daily prednisone-equivalent dose requirements, determined during the observation month preceding initiation of treatment and compared to the month preceding the seventh infusion. Secondary clinical endpoints measured were pulmonary function, frequency of emergency room visits or hospitalizations, and number of days absent from school or work. When adjusted for body weight, the mean dose requirements fell by 33, 39, and 33% in the placebo, IVIG (1 g/kg), and IVIG (2 g/kg) treatment arms, respectively. The differences between therapies were not statistically different (P = 0.9728). The mean percentage-of-predicted FEV1 fell in all three treatment groups during the treatment period but there was no significant difference between treatment groups (P = 0.8291). There was also no significant difference in the percentage of subjects requiring emergency room visits or hospitalizations or missing days of work/school, among the three treatment groups. The trial was terminated prematurely after interim analysis determined the adverse experience rate was different between the three groups. Three patients, all randomized to the 2-g/kg IVIG dose group, were hospitalized with symptoms consistent with aseptic meningitis. In summary, in this randomized, double-blind, placebo-controlled multicenter study, high doses of IVIG did not demonstrate a clinically or statistically significant advantage over placebo (albumin) infusions for the treatment of corticosteroid-dependent asthma. Subgroup analysis failed to identify markers predicting responsiveness. High-dose IVIG can also be associated with a significant incidence of serious adverse events.

Effect of ethanol on monocytic function in human immunodeficiency virus type 1 infection.

We have developed a novel system to study monocytic function after human immunodeficiency virus type 1 (HIV-1) infection by infecting a series of human macrophage hybridoma cell lines with HIV-1. Since ethanol has detrimental effects on immune function, we investigated the effect of ethanol and its metabolites acetaldehyde and acetate on monocytic function by utilizing one human macrophage hybridoma cell line, clone 43, as well as primary monocytes. Pretreatment of clone 43 and primary monocytes with ethanol and its metabolites resulted in diminished accessory cell function for mitogen-, anti-CD3-, and antigen-induced T-cell proliferation. The decreased accessory cell function was associated with reduced interleukin 1alpha (IL-1alpha), IL-1beta, and tumor necrosis factor alpha production with loss of intracellular cytokine and mRNA production and the induction of transforming growth factor beta. In ethanol-, acetaldehyde-, and acetate-treated HIV-1-infected clone 43 cells (43HIV), there was a more rapid loss (3 days after infection) of accessory cell function at a lower infecting dose of HIV-1 than that in untreated 43HIV cells. We also observed a more rapid loss of surface class II antigen expression in the ethanol-, acetaldehyde-, and acetate-treated 43HIV cells, but no change in surface expression of CD80 or CD86. Ethanol-induced impairment of monocytic function may compound the immunologic defects of AIDS, making the infected individual more susceptible to the complications of the disease.

Chronically HIV-1-infected monocytic cells induce apoptosis in cocultured T cells.

We have previously developed a human macrophage hybridoma model system to study the effect of HIV-1 infection on monocytic function. Upon coculture of one chronically (35 days postinfection) HIV-1-infected human macrophage hybridoma cell line, 43HIV, there was a dose-dependent decrease in the viability of cocultured Ag-stimulated T cells associated with an increase in DNA strand breaks. Enhanced apoptosis was determined by labeling with biotinylated dUTP and propidium iodide, increased staining with annexin V, increased side light scatter and expression of CD95, and decreased forward light scatter and expression of Bcl-2. There was also increased DNA strand breaks as determined by propidium iodide staining in unstimulated T cells cocultured with 43HIV and in T cells stimulated with anti-CD3 mAb and PHA. Pretreatment with 5145, a human polyclonal anti-gp120 Ab that recognizes the CD4 binding region, as well as with an anti-Fas ligand mAb blocked apoptosis in CD4+ T cells but not in CD8+ T cells. A soluble factor with a Mr below 10,000 Da was defined that induced apoptosis in CD4+ and CD8+ T cells and B cells. SDS-PAGE analysis of the active fractions revealed a band of 6000 Da that, after electroelution, had proapoptotic activity. The pI of the activity was estimated to be between 6.5 and 7.0. In conclusion, chronically HIV-1-infected monocytic cells induce apoptosis in bystander-, Ag-, anti-CD3-, and mitogen-stimulated T cells by multiple factors, which may contribute to the depletion of lymphocytes induced by HIV-1.

Immunoglobulin and IgG subclass levels in the African American and Hispanic populations of east Harlem.

BACKGROUND: The normal levels of immunoglobulin and IgG subclasses in African American and Hispanic populations are uncertain. To determine immunoglobulin and IgG subclass levels in this community, we measured serum IgG, IgM, and IgA levels along with IgG subclasses in 303 African American and Hispanic patients in a general medical clinic and an allergy/asthma clinic in East Harlem in New York City. METHODS: Prospective measurement of immunoglobulins and IgG subclasses in a general medical clinic and an allergy/asthma clinic in East Harlem. RESULTS: Ten (3.4%) patients had IgG levels below the lower limit of normal values, two (0.07%) patients had IgA levels below the lower limit of normal values, and two (0.07%) patients had an IgM level below the lower limit of normal values. Twenty-four (8.1%) patients had IgG subclass levels below the lower limit of normal values; 1 patient had low levels of IgG1 and IgG3, 5 patients had low levels of IgG2, and 18 patients had low levels of IgG3. Because low IgG subclasses and allergy/asthma appeared to be associated, we compared IgG subclass levels of the patients with and without allergy/asthma. The mean IgG2 level in the patients without allergy/asthma was 425.1 +/- 199.1 mg/dL (p = 0.05) compared with 345.5 +/- 133.1 mg/dL in the allergy/asthma group, the mean IgG3 level in the patients without allergy/asthma was 85.0 +/- 57.1 mg/dL compared with 64 +/- 34.1 mg/dL in the allergy/asthma group (p = 0.016) but there were no differences in IgG1 and IgG4 levels between the two groups. CONCLUSION: Altogether, our data indicate that humoral immunoglobulin and IgG subclass levels below the lowest normal values occur in the low socioeconomic African American and Hispanic populations, especially in patients with asthma in East Harlem.