Thomas E. Fehniger

Early reduction of immune activation in lymphoid tissue following highly active HIV therapy.

Objective:To evaluate immune reconstitution within HIV-infected lymphoid tissue during highly active antiretroviral therapy (HAART). Design and methods:In situ cellular responses were studied in sequential tonsillar biopsies in three asymptomatic HIV-infected (CD4 cells greater than 400 × 106/l) antiretroviral treatment-naive volunteers enrolled in a clinical trial to determine the early effect of HAART. Computerized image analysis was used to study immunohistochemically stained sequential tonsil sections for the patterns of local cytokine production, chemokine receptor expression and cellular distribution. Replicate quantitative assessments of samples before and after 4 weeks of therapy were used for the evaluation of drug effects and compared with four uninfected controls. Tonsillar HIV proviral-DNA was determined by fluorescent in situ 5′-nuclease assay. Results:HIV-infected tonsil tissue was characterized by extensive pro-inflammatory and type 1 cytokine expression. A five- to 15-fold elevation of interleukin (IL)-1α, IL-12, IL-2 and interferon (IFN)-γ protein expression was found compared with controls, and each encompassed a mean of at least 4.5% of the tissue compartment. This was reduced by 20–90% in all individuals after 4 weeks of HAART. In contrast, type 2 cytokine expression (IL-4, IL-10), plus tumour necrosis factor (TNF)-α, remained low throughout the study. HAART reduced, by 40%, the expression of HIV co-receptors, CCR5 and CXCR4, which initially were elevated four to six times over the control values. In addition, the myelomonocytic inflammatory proteins, CD68 and calprotectin, diminished by 26–83% after therapy. The HIV RNA was reduced to undetectable levels in plasma by HAART. However, a large pool of tonsil cells (2–7%), remained HIV DNA positive after 4 weeks of therapy. Conclusions:Although immune activation may be the direct consequence of HIV replication, HAART-associated reconstitution begins with a reduction in inflammatory cytokine production which precedes the elimination of local proviral reservoirs.

Perforin is not co-expressed with granzyme A within cytotoxic granules in Cd8 T lymphocytes present in lymphoid tissue during chronic Hiv infection

BACKGROUNDnResidual HIV-1-infected cells are poorly eliminated from lymphoid tissue (LT) reservoirs by effector cytotoxic T lymphocytes (eCTL) despite antiretroviral therapy. Perforin and granzyme A (grA) constitute major effector molecules within eCTL granules that induce apoptosis and lysis of virally infected cells.nnnOBJECTIVEnExpression of perforin and grA was studied at the single cell level in LT and blood from 16 patients infected with HIV-1 (stage A1-C) who were not taking antiretroviral therapy.nnnMETHODnImmunohistochemical analysis by in situ imaging of cells from blood and LT.nnnRESULTSnQuantitative in situ imaging showed that perforin-expressing CD8 T cells comprised 0.3-1.5% of total cells within the LT from recent HIV-1 seroconverters, while grA was found in 2.1-7.2% of total cells. However, despite high-level grA upregulation (1.5-4.5% of total cells) compared with that in non-infected individuals (0.4-0.9%), perforin expression remained low (< 0.1% of total cells) (P < 0.02) in LT from patients with chronic HIV-1 infection (stage A2-C). This contrasted with findings in peripheral blood mononuclear cells (PBMC) from the same HIV-1 infected cohort where perforin was detected in 13-31% of all PBMC, which was 10- to 100-fold higher than in lymphoid tissue (P < 0.001); grA was found in 14-32% of total PBMC. Two-colour staining showed that granular expression of perforin and grA was restricted to CD8 T cells in over 90% of total cells in both LT and blood.nnnCONCLUSIONSnThese findings indicate that cytotoxic perforin expression is impaired at local sites of HIV replication within lymphoid tissue. Since perforin is required together with grA for granule-mediated cytolysis, the low perforin expression in the LT may limit the ability of eCTL to eliminate HIV-1 infected cells in lymphoid tissue.

Low levels of perforin expression in CD8+ T lymphocyte granules in lymphoid tissue during acute human immunodeficiency virus type 1 infection

Human immunodeficiency virus (HIV)-specific cytotoxic T lymphocyte (CTL) responses are detectable shortly after the acute phase of HIV infection, but they cannot control viral replication and prevent development of chronic immune suppression. This article describes a defect in the coexpression of perforin in granzyme A-positive CD8(+) T cells in lymphoid tissue from patients with acute HIV infection and a reduction in the perforin-dependent nuclear translocation of granzyme A. Furthermore, intracellular levels of HIV DNA and RNA found in lymphoid tissue were higher (10-100 times) than those found in blood, and blood samples showed more-coordinated cellular perforin/granzyme A expression. This suggests that mechanisms inhibiting CTL-mediated cytotoxicity are operative in lymphoid tissue early in the course of HIV infection.

Computerized assessment of production of multiple human cytokines at the single-cell level using image analysis.

A technique using a computerized image analysis system was developed for evaluating and quantifying human cytokine production. This system registered single cells as positive or negative cytokine producers based on a specific juxtanuclear staining pattern generated by accumulation of the proteins in the Golgi‐endoplasmatic reticulum compartment. The characteristic morphology of the immunocytochemical staining offered the opportunity to register individual producer cells within multicomponent cell populations. A color camera was then adapted to transfer on‐line images directly into the computer‐controlled operating system. In this study cultured human peripheral blood mononuclear cells were polyclonally stimulated and then analyzed for interleukin‐1α (IL‐1α), IL‐1β, IL‐1ra, IL‐2, IL‐4, IL‐6, IL‐8, IL‐10, tumor necrosis factor‐α (TNF‐α), TNF‐β, interferon‐γ, granulocyte colony‐stimulating factor and granulocyte‐macrophage colony‐stimulating factor production. The image‐analyzing system detected cytokine‐producing cells in a sensitive and reproducible manner, which was in total congruence with enumeration by conventional microscopy. Furthermore, accurate assessments of cell distributions by signal intensity and cell area were applied at the single‐cell level. The image‐analyzing system allowed the detection of at least 1 in 1,000 events by using unique cytokine‐associated morphometric criteria. The results of kinetic studies measuring cytokine production following activation and cell transformation provided data supporting increases in intensity of intracellular localized specific immunostaining and in cell size within the cytokine‐producing cells.

Interstitial pneumonitis in bone marrow transplant recipients is associated with local production of TH2-type cytokines and lack of T cell-mediated cytotoxicity

BACKGROUNDnInterstitial pneumonitis, especially associated with cytomegalovirus (CMV) infection, is a serious complication after bone marrow transplantation (BMT), with a high fatality rate despite adequate antiviral treatment. The aim of this study was to elucidate the local immunopathogenesis of interstitial pneumonitis caused by CMV or other agents in BMT recipients.nnnMETHODSnCryopreserved lung tissue obtained from 12 patients with interstitial pneumonitis following BMT was analyzed for cytokine production at the single-cell level using a cytokine-specific monoclonal antibody and immunohistochemical technique. Cytokine production in individual cells was analyzed using monoclonal antibodies to 23 different human cytokines: interleukin (IL)-1 to IL-13, tumor necrosis factor (TNF)-alpha, TNF-beta, interferon-gamma (IFNgamma), granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and transforming growth factor (TGF)-beta1 to 3.nnnRESULTSnMarrow transplant patients with interstitial pneumonia had increased numbers of infiltrating alveolar macrophages, CD3+, CD4+ T cells, and CD40+ B cells and significantly increased numbers of IL-4-, IL-10-, IL-1-, TGF-beta1-, TGF-beta2-, and TGF-beta3-producing cells than controls. IL-2-, IFN-gamma-, and TNF-beta-producing cells were undetectable in most patients with CMV pneumonitis (n=7). Neither perforin-positive CD8+ T lymphocytes nor up-regulation of the apoptotic pathway was detected in lung tissue from patients with interstitial pneumonia. In contrast, extensive local production of IgA, IgG, and IgM was demonstrated in all patients. Intracellular and extensive extracellular deposition of CD68, the L-1 antigen synthesized in CD14+ macrophages, was found.nnnCONCLUSIONSnThe cytokine profile suggested that Th1-type cytokine production was absent, whereas production of Th2-type cytokines was significantly up-regulated. Interstitial pneumonitis in BMT recipients with fatal outcome (11/12 patients) was associated with dysregulation in the local cytokine network notable for a predominant Th2 immune response with minimal or absent T cell-mediated cytotoxicity.

Targeted Suppression of Cytokine Production in Monocytes but Not in T Lymphocytes by a Tetravalent Guanylhydrazone (CNI-1493)

Image analysis was used to study the cytokine-inhibitory effect of the nitric oxide inhibitor tetravalent guanylhydrazone (CNI-1493) in individual immunocytochemically stained human peripheral blood mononuclear cells (PBMC). CNI-1493 inhibited lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-alpha, interleukin (IL)-1alpha, IL-1beta, IL-6, and IL-8 production whether or not LPS stimulation was enhanced by interferon (IFN)-gamma priming. Addition of TNF-alpha to CNI-1493-exposed LPS-stimulated cells partially restored the incidence of IL-1alpha-, IL-1beta-, and IL-8-producing cells. TNF-alpha production induced by costimulation by ligation of CD3 and CD28 was inhibited by CNI-1493 in monocytes but not in T lymphocytes. The prevalence of IL-2-, IFN-gamma-, and TNF-beta-producing T cells was not reduced by CNI-1493. Phorbol ester and ionomycin activation also resulted in a CNI-1493 -induced inhibition of TNF-alpha in monocytes but resistant production of TNF-alpha, IL-2, and IFN-gamma by T cells. Thus, CNI-1493 preferentially inhibited synthesis of proinflammatory cytokines in monocytes.

Comparison of parasitological and immunological methods in the diagnosis of leishmaniasis in Ethiopia

The sensitivity and specificity of parasite demonstration methods (smear, culture and histology) and serological assays (enzyme-linked immunosorbent assay [ELISA], direct agglutination test and immunoblot) were compared in the diagnosis of leishmaniasis in Ethiopia. Culture was found to be the most sensitive diagnostic method, followed by ELISA, for the diagnosis of cutaneous leishmaniasis (CL). When the clinical type of CL was taken into consideration, serological and parasitological methods were equally good for the diagnosis of diffuse cutaneous leishmaniasis. Overall, the serological assays were not sensitive enough to diagnose all the parasitologically confirmed cases of localized cutaneous leishmaniasis. Both groups of diagnostic methods performed equally well in the diagnosis of visceral leishmaniasis patients. In cases of CL where clinical diagnosis was a problem and histology could not give a definitive diagnosis due to the absence of demonstrable parasites, one of the serological assays, preferably ELISA, was very useful in establishing the final diagnosis.

HIV-1 exposed dendritic cells show increased pro-inflammatory cytokine production but reduced IL-1ra following lipopolysaccharide stimulation

OBJECTIVESnDendritic cells (DC) are potential first target cells in sexually transmitted HIV-1 infection. They are also considered to be central in the activation of naive T cells, which thereupon can become permissive for HIV-1. In addition, activated DC express effector molecules, which likely contribute to the direction of T helper (Th1/Th2)-specific immune responses.nnnMETHODSnThe capacity of cytokine and chemokine production in in vitro DC infected and uninfected with HIV-1 was assessed by enzyme-linked immunosorbent assay (ELISA) and by in situ immunocytochemical detection at the single cell level. Fluorescent in situ 5-nuclease assay (FISNA) was used for quantitative evaluation of HIV-1 gag-positive cells.nnnRESULTSnMacrophage-tropic HIV-1 effectively infected 20-40% of in vitro cultured DC. However, this activity alone did not induce detectable cytokine or chemokine protein expression in DC. In contrast, lipopolysaccharide (LPS) stimulation of these HIV-1-infected DC resulted in a significantly increased level of cells producing tumour necrosis factor alpha (TNF-alpha) and interleukin (IL) 1beta but reduced frequencies of cells producing IL-1 receptor antagonist (IL-1ra) compared with the LPS-stimulated but uninfected DC cultures (P < 0.05). Furthermore, an extensive production of the beta-chemokines [RANTES, macrophage inflammatory proteins (MIP) 1alpha and 1beta] was detected in DC in response to both LPS and HIV-1 plus LPS.nnnCONCLUSIONSnThese findings indicate that HIV-1 infected DC may have an increased proinflammatory activity. Elevated production of cytokines such as TNF-alpha and IL-1beta and reduced IL-1ra may contribute to enhanced replication of HIV-1 in bystander T cells. Gram-negative bacterial infection and gut-associated bacterial translocation in HIV-1-infected individuals may also result in endotoxin-mediated reactivation of HIV-1 in bystander CD4 CD45RO T cells caused by the increased production of proinflammatory cytokines in DC.

Immune responses to fractionated cytomegalovirus (CMV) antigens after HIV infection. Loss of cellular and humoral reactivity to antigens recognized by HIV-, CMV+ individuals

In order to delineate the molecular pathogenesis of the increased susceptibility to CMV disease in HIV infection, the patterns of antigen responsiveness in HIV‐infected and non‐infected individuals were investigated. CMV was fractionated by SDS‐PAGE and electroblotted onto nitrocellulose. Lymphoproliferative responses of healthy HIV–, CMV+ individuals and HIV+, CMV+ asymptomatic patients to a whole CMV antigen preparation and to 20 fractions of nitrocellulose‐bound CMV were then compared. Three fractions of approximate molecular weight of 130–165, 65–75, and 55–65 kD appeared to contain the major T cell stimulating antigens for HIV, CMV– individuals. A statistically significant depression of responses to fractions containing antigens in the ranges of 130–165 kD and 55–65 kD but not to whole CMV was seen in HIV+ individuals compared with controls. In healthy controls, the sum of the proliferative responses as measured by 3H‐thymidine uptake to these three major fractions was approximately equal to the response to a whole CMV antigen preparation, whereas it was less than half of this response in five out of six HIV+ subjects. When antibody activities to CMV antigens were analysed by immunoblotting of sera from the two subject groups and also sera of ARC and AIDS patients, a selective loss of reactivity was revealed in 10 out of 19 HIV+ subjects to a band of 26–28 kD whereas all 15HIV–, CMV+ controls recognized this band. Serum IgG and IgM values were both significantly higher in HIV+ individuals than in controls. These findings suggest that specific lesions in the repertoire of immune responsive CMV antigens occur in HiV+ individuals.

Quantitative single cell methods that identify cytokine and chemokine expression in dendritic cells

Two techniques based upon flow cytometry (FCM) and in situ image analysis were developed for quantification of intracellular cytokine and chemokine protein expression at the single cell level in dendritic cells (DCs). The qualitative and quantitative differences between the two methods were evaluated. In vitro differentiated DCs were stimulated with lipopolysaccaride (LPS) and thereafter stained for either IL-8, which is secreted through the Golgi-organelle, or IL-1ra, which localises diffusely in the cytoplasm. Microscopic examination, both for fluorophore and enzymatically stained cells, showed that DCs expressed IL-8 and IL-1ra with two different staining patterns. FCM analysis showed high frequencies of IL-1ra producing cells (76+/-13%), which was similar to the frequency obtained by in situ imaging. However, in contrast to IL-1ra, the incidence of IL-8 expressing DCs showed high variability between the donors. The numbers of positive cells were 19+/-19% as measured by FCM. The detection of IL-8 analysed by in situ imaging revealed higher frequencies (26+/-14%). The addition of brefeldin-A, leading to cytoplasmic accumulation of proteins secreted through the Golgi endoplasmatic route, generated a significantly increased signal intensity and incidence of producer cells, resulting in similar frequencies for both methods. FCM has the advantage of being less time consuming than image analysis and is also able to facilitate multiple colour analysis. However, FCM is less accurate in detecting and quantifying cytokines and chemokines with a preserved juxtanuclear staining pattern. The correct choice of detection technique therefore depends on the study question.