Emergence of Epstein-Barr virus-associated haemophagocytic syndrome upon treatment of systemic lupus erythematosus.

A 32-year-old female patient with systemic lupus erythematosus was admitted to our hospital with fever and cytopenia, and diagnosed as haemophagocytic syndrome (HPS) by bone marrow aspiration study showing haemophagocytosis. Since the serologic activity of lupus was not increased at that time and HPS was refractory to the conventional therapies, an additional aetiological factor was suspected. Real-time PCR analysis identified reactivation of Epstein-Barr virus (EBV). A combination therapy targetting EBV-associated HPS, consisting of intravenous administration of cyclosporine A as well as immunoglobulin with a high titre of anti-EBV antibody, significantly suppressed EBV viraemia and led to the remission of HPS until the time of writing.

A milk protein lactoferrin enhances human T cell leukemia virus type I and suppresses HIV-1 infection.

Human T cell leukemia virus type I (HTLV-I) and HIV-1, causative agents of adult T cell leukemia/lymphoma and AIDS, respectively, are transmitted vertically via breast milk. Here we demonstrate that lactoferrin, a milk protein that has a variety of antimicrobial and immunomodulatory activities, facilitates replication of HTLV-I in lymphocytes derived from asymptomatic HTLV-I carriers and transmission to cord blood lymphocytes in vitro. Transient expression assays revealed that lactoferrin can transactivate HTLV-I long terminal repeat promoter. In contrast, lactoferrin inhibits HIV-1 replication, at least in part, at the level of viral fusion/entry. These results suggest that lactoferrin may have different effects on vertical transmission of the two milk-borne retroviruses.

Reciprocal interactions between human T-lymphotropic virus type 1 and prostaglandins: implications for viral transmission.

Human T-lymphotropic virus type 1 (HTLV-1), the etiologic agent of adult T-cell leukemia/lymphoma, is transmitted through breast milk and seminal fluid, which are rich in prostaglandins (PGs). We demonstrate that PGE(2) upregulates the HTLV-1 long terminal repeat promoter through the protein kinase A pathway, induces replication of HTLV-1 in peripheral blood mononuclear cells (PBMC) derived from asymptomatic carriers, and enhances transmission of HTLV-1 to cord blood mononuclear cells (CBMC). Furthermore, HTLV-1 Tax transactivates a promoter for cyclooxygenase 2, a PG synthetase, and induces PGE(2) expression in PBMC or CBMC. Thus, HTLV-1 interacts with and benefits from PGs, constituents of its own vehicle for transmission.

Octamer transcription factors up-regulate the expression of CCR5, a coreceptor for HIV-1 entry.

T cell activation can induce expression of CCR5, a major coreceptor for macrophage-tropic (R5) human immunodeficiency virus type 1 (HIV-1). Here we report that overexpression of the Oct-2 transcription factor and octamer coactivator BOB.1/OBF/OCA-B, both of which are induced in T cells following T cell receptor signaling, synergistically up-regulates CCR5 promoter activity via interaction with an octamer motif on the promoter. We also show that the octamer transcription factors can increase cell surface expression of CCR5 and fusogenicity of the cells with R5 HIV-1 Env. These results suggest that octamer transcription factors may play a critical role in the induction of CCR5 expression on, and thereby susceptibility to, R5 HIV-1 of T cells following antigenic stimulation.

In vitro induction of HIV-1 replication in resting CD4(+) T cells derived from individuals with undetectable plasma viremia upon stimulation with human T-cell leukemia virus type I.

Microbial coinfections have been associated with transient bursts of human immunodeficiency virus (HIV) viremia in patients. In this study we investigated whether human T-cell leukemia virus type I (HTLV-I), another human retrovirus that is prevalent among certain HIV-infected populations, can induce HIV-1 replication in patients who had been successfully treated with highly active antiretroviral therapy. We demonstrate that supernatants from HTLV-I-producing MT-2 cells can induce in vitro replication of HIV-1 from highly purified, resting CD4(+) T cells obtained from individuals with undetectable plasma viremia. Depletion of proinflammatory cytokines from the supernatants reduced, but did not abrogate, the ability to induce HIV-1 replication, indicating that other factors such as HTLV-I Tax or Env also have a role. The HTLV-I-mediated effect does not require productive infection: exposure to heat-inactivated HTLV-I virions, purified Tax protein, or HTLV-I Env glycoprotein also induced expression of HIV-1. Furthermore, we demonstrate that coculture of resting CD4(+) T cells with autologous CD8(+) T cells markedly inhibits the HTLV-I-induced virus replication. Our results suggest that coinfection with HTLV-I may induce viral replication in the latent viral reservoirs; however, CD8(+) T cells may play an important role in controlling the spread of virus upon microbial stimulation.

Herpes simplex virus infection induces replication of human immunodeficiency virus type 1.

Genital herpes has been associated with increased efficiency of the sexual transmission and enhanced replication of human immunodeficiency virus type 1 (HIV-1). In this study we demonstrate that exposure to infectious or heat-inactivated herpes simplex virus (HSV) type 1 or 2 virions increases HIV-1 expression in macrophages at least in part by inducing NF-kappaB activity. Neutralizing antibodies to the HSV glycoprotein gB or gD markedly attenuated these virion-mediated effects on HIV-1 expression in macrophages. Thus HSV infection of macrophages that reside in genital mucosal tissue induces HIV-1 replication in these cells. Our study may have implications for the management of patients who are coinfected with the two viruses.

Class I-unrestricted noncytotoxic anti-HTLV-I activity of CD8(+) T cells.

Although it is widely believed that viral clearance is mediated principally by the destruction of infected cells by cytotoxic T cells, noncytolytic antiviral activity of CD8(+) T cells may play a role in preventing the progression to disease in infections with immunodeficiency viruses and hepatitis B virus. We demonstrate here that (1) replication of human T-lymphotropic virus type I (HTLV-I) is more readily detected from CD8(+) T-cell-depleted (CD8(-)) peripheral blood mononuclear cells (PBMCs) of healthy HTLV-I carriers than from unfractionated PBMCs, (2) cocultures of CD8(-) PBMCs with autologous or allogeneic CD8(+) T cells suppressed HTLV-I replication, and (3) CD8(+) T-cell anti-HTLV-I activity is not abrogated in trans-well cultures in which CD8(+) cells are separated from CD8(-) PBMCs by a permeable membrane filter. These results suggest that class I-unrestricted noncytolytic anti-HTLV-I activity is mediated, at least in part by a soluble factor(s), and may play a role in the pathogenesis of HTLV-I infection. (Blood. 2000;96:1994-1995)

Cathepsin G, a neutrophil-derived serine protease, increases susceptibility of macrophages to acute human immunodeficiency virus type 1 infection.

Neutrophils dominate acute inflammatory responses that generally evolve into chronic inflammatory reactions mediated by monocyte/macrophages and lymphocytes. The latter cell types also serve as major targets for human immunodeficiency virus type 1 (HIV-1). In this study we have investigated the role of neutrophil products, particularly cathepsin G, in HIV infection. Cathepsin G induced chemotaxis and production of proinflammatory cytokines by macrophages but not CD4(+) T cells. Pretreatment with cathepsin G markedly increased susceptibility of macrophages but not CD4(+) T cells to acute HIV-1 infection. When macrophages were exposed to pertussis toxin prior to cathepsin G treatment, the cathepsin G-mediated effect was almost abrogated, suggesting that enhancement of HIV-1 replication by cathepsin G requires Gi protein-mediated signal transduction. Although prolonged exposure to cathepsin G suppressed HIV infection of macrophages, serine protease inhibitors, which are exuded from the bloodstream later during inflammatory processes, neutralized the inhibitory effect. Neutrophil extracts or supernatants from neutrophil cultures, which contain cathepsin G, had effects similar to purified cathepsin G. Thus, cathepsin G, and possibly other neutrophil-derived serine proteases, may have multiple activities in HIV-1 infection of macrophages, including chemoattraction of monocyte/macrophages (HIV-1 targets) to inflamed tissue, activation of target cells, and increase in their susceptibility to acute HIV-1 infection.

In vitro reactivation of human immunodeficiency virus 1 from latently infected, resting CD4+ T cells after bacterial stimulation.

Microbial coinfections have been associated with transient bursts of human immunodeficiency virus (HIV) viremia in patients. In this study, we have investigated whether microbial coinfections can induce replication of HIV-1 in latently infected CD4(+) T cells derived from HIV-infected patients who are receiving highly active antiretroviral therapy and in whom plasma viremia is undetectable by sensitive assays. We demonstrate that supernatants from macrophages exposed to the bacterial product lipopolysaccharide can induce in vitro activation of HIV-1 from latently infected, resting CD4(+) T cells obtained from HIV-infected individuals. Depletion of proinflammatory cytokines from the supernatant markedly reduced-whereas depletion of ss chemokines increased--the ability of the supernatant to induce replication of HIV-1. Our results suggest that coinfection with microbial pathogens such as bacteria may induce viral replication in the latent viral reservoirs in vivo.

[Role of intravascular ultrasound imaging for assessing pathophysiology of coronary artery disease].

It has been nine years since intravascular ultrasound imaging(IVUS) was for the first time performed in Japan at our hospital. During this period, the progress of catheter technology brought about many improvements in catheter design and image quality. Also clinical utility of IVUS has been widely recognized with accumulation of clinical experiences. The most important feature of this method is the capability of both quantitative and qualitative analyses of the atheroma. IVUS has mainly been used to help guide procedures during catheter interventions and has provided information about the mechanisms of dilatation and restenosis. Recently, the ability of IVUS in diagnosing morphologic changes such as compensatory enlargement, vessel shrinkage and plaque rupture has much attention. IVUS should enhance our understanding of the pathophysiology of coronary artery disease.

Inefficient formation of a complex among CXCR4, CD4 and gp120 in U937 clones resistant to X4 gp120-gp41-mediated fusion.

Certain subclones (designated as minus clones) of the promonocytic U937 cell line do not support efficient infection and fusion mediated by T cell line adapted (TCLA) X4 HIV-1 gp120-gp41 (Env) although the CXCR4 and CD4 concentrations at their surfaces are similar to those at the surfaces of clones susceptible to HIV-1 entry (plus clones) (H. Moriuchi et al., J. Virol. 71, 9664-9671, 1997). To test the hypothesis that inefficient formation of gp120-CD4-CXCR4 complexes could contribute to the mechanism of resistance to Env-mediated fusion in the minus clones, we incubated plus and minus cells with HIV-1 LAI gp120 and coimmunoprecipitated CD4 by using anti-CXCR4 antibodies. The gp120 induced inefficient coimmunoprecipitation of CD4 in the minus clones but not in the plus ones. Overexpression of CD4 resulted in significant restoration of the minus clones' susceptibility to fusion in parallel with an increase in the amount of the gp120-CD4-CXCR4 complexes. These results not only suggest that the resistance to TCLA X4 HIV-1 entry in the U937 minus clones is due to the inability of these cells to efficiently form complexes among CD4, gp120, and CXCR4, but also provide a direct evidence for the correlation between fusion and the cell surface concentration of the complexes among CXCR4, CD4, and gp120. These data and similar recent observations in macrophages suggest that inefficient complex formation among CXCR4, CD4, and gp120 could be a general mechanism of cell resistance to gp120-gp41-mediated fusion and a major determinant of HIV-1 evolution in vivo.

HTLV type I Tax activation of the CXCR4 promoter by association with nuclear respiratory factor 1.

Human T lymphotropic virus type I trans-activator Tax protein regulates expression of several cellular genes that are involved in cellular activation, proliferation, and transformation. Tax mediates its regulatory activity through interaction with cellular transcription factors such as members of the cAMP-responsive element-binding factors/ATF family or the NF-kappaB/Rel family. In this study we have demonstrated that Tax trans-activates the promoter for CXCR4, a coreceptor for T cell-tropic HIV-1 through its association with nuclear respiratory factor 1 (NRF1). The promoter region for CXCR4 contains an NRF1-binding site, which is crucial for basal and Tax-induced activity. Glutathione S-transferase (GST) pull-down experiments showed association of GST-Tax fusion protein with NRF1 in vitro. Expression of Tax, in addition to stimulation with phorbol myristate acetate and ionomycin, increased formation of the NRF1 complex in a gel-mobility shift assay, indicating that Tax association with NRF1 in vivo facilitates its DNA binding. HTLV-I Tax activation of CXCR4 may contribute to the rapid progression of HIV disease observed in certain coinfected individuals.

Induction of HIV-1 replication by allogeneic stimulation.

Allogeneic stimulation presents an immunologic challenge during pregnancy, blood transfusions, and transplantations, and has been associated with reactivation of latently infected virus such as CMV. Since HIV-1 is transmitted vertically, sexually, or via contaminated blood, we have tested the effects of allostimulation on HIV-1 infection. 1) We show that allostimulated lymphocytes are highly susceptible to acute infection with T cell-tropic or dual-tropic HIV-1. 2) We show that allostimulation has dichotomous effects on replication of macrophage-tropic HIV-1; it activates HIV expression in already infected cells but inhibits HIV entry by secreting HIV-suppressive CC chemokines. 3) We show that allogeneic stimulation of latently infected, resting CD4+ T cells induced replication of HIV-1 in these cells. These observations suggest that allogeneic stimulation may play a role in the transmission, replication, and phenotypic transition of HIV-1.

USF/c-Myc enhances, while Yin-Yang 1 suppresses, the promoter activity of CXCR4, a coreceptor for HIV-1 entry.

Transcription factors USF1 and USF2 up-regulate gene expression (i.e. , HIV-1 long terminal repeats) via interaction with an E box on their target promoters, which is also a binding site for c-Myc. The c-Myc oncoprotein is important in control of cellular proliferation and differentiation, while Yin-Yang 1 (YY1) has been shown to control the expression of a number of cellular and viral genes. These two proteins physically interact with each other and mutually inhibit their respective biological functions. In this study, we show that USF/c-Myc up-regulates, while YY1 down-regulates the promoter activity of CXCR4, a coreceptor for T cell-tropic HIV-1 entry. We have identified an E box around -260 and a YY1 binding site around -300 relative to the transcription start site. Mutation of the E box abolished USF/c-Myc-mediated up-regulation of CXCR4 promoter activity, and mutation of the YY1 binding site was associated with unresponsiveness to YY1-mediated inhibition. These data suggest that USF/c-Myc and YY1 may play an important role in the HIV-1-replicative cycle, by modulating both the viral fusion/entry process and viral expression.

Clinical utility of negative contrast intravascular ultrasound to evaluate plaque morphology before and after coronary interventions.

Although intravascular ultrasound (IVUS) is used for evaluation of plaque volume and lumen size as well as detection of vessel wall structures after catheter-based interventions, differentiation between the lumen and plaque structures can be difficult. This study attempted to evaluate the efficacy of negative contrast IVUS imaging for assessment of vessel wall morphology after coronary interventions. IVUS studies were performed in 67 lesions in 66 patients before and after coronary interventions. After the baseline ultrasound imaging run, warm 5% glucose solution was injected manually through the guiding catheter into the coronary artery to washout blood from the lumen to avoid speckled reflections from red blood cells (negative contrast). Quantitative measurements were obtained and plaque morphology was assessed for the presence and extent of medial dissections and intimal flaps. There was no difference in each quantitative parameter between baseline images and negative contrast images. The vessel wall boundary was clearly delineated from the lumen, which was defined as effective negative contrast in 51 of 67 lesions (76%). The baseline images revealed plaque dissection in 9 lesions (18%) and an intimal flap in 13 lesions (25%). In addition, 4 dissections (8%) and 16 intimal flaps (31%) were visualized during the infusion of negative contrast. Additional treatment was performed in 4 lesions (8%) based on the images with negative contrast. Negative contrast IVUS was more sensitive in demonstrating a plaque fracture than were baseline images. This method is useful for enhancing the diagnostic capability of IVUS imaging and may influence the decision-making process during interventional procedures.

Exposure to bacterial products renders macrophages highly susceptible to T-tropic HIV-1.

Microbial coinfections variably influence HIV-1 infection through immune activation or direct interaction of microorganisms with HIV-1 or its target cells. In this study, we investigated whether exposure of macrophages to bacterial products impacts the susceptibility of these cells to HIV-1 of different cellular tropisms. We demonstrate that () macrophages exposed to bacterial cell wall components such as lipopolysaccharide (LPS) (Gram-negative rods), lipoteichoic acid (Gram-positive cocci), and lipoarabinomannan (Mycobacteria) become highly susceptible to T cell (T)-tropic HIV-1 (which otherwise poorly replicate in macrophages) and variably susceptible to macrophage (M)-tropic HIV-1; () LPS-stimulated macrophages secrete a number of soluble factors (i.e., chemokines, interferon, and proinflammatory cytokines) that variably affect HIV infection of macrophages, depending on the virus phenotype in question; and () LPS-stimulated macrophages express CCR5 (a major coreceptor for M-tropic HIV-1) at lower levels and CXCR4 (a major coreceptor for T-tropic HIV-1) at higher levels compared with unstimulated macrophages. We hypothesize that a more favorable environment for T-tropic HIV-1 and a less favorable or even unfavorable environment for M-tropic HIV-1 secondary to exposure of macrophages to those bacterial products may accerelate a transition from M- to T-tropic viral phenotype, which is indicative of disease progression.

Intracoronary ST-segment alternans during coronary balloon angioplasty.

ST-segment alternans has been described in experimental coronary artery occlusion and in patients with variant angina. It is also seen during coronary angioplasty. This report describes a patient who on balloon inflation during coronary angioplasty demonstrated ST-segment alternans only on intracoronary electrocardiogram but did not on surface 12 lead electrocardiogram. Hemodynamic pulsus alternans of the aortic pressure tracing was not observed during electrical alternans.

Factors secreted by human T lymphotropic virus type I (HTLV-I)-infected cells can enhance or inhibit replication of HIV-1 in HTLV-I-uninfected cells: implications for in vivo coinfection with HTLV-I and HIV-1.

It remains controversial whether human T lymphotropic virus type I (HTLV-I) coinfection leads to more rapid progression of human immunodeficiency virus (HIV) disease in dually infected individuals. To investigate whether HTLV-I infection of certain cells can modulate HIV-1 infection of surrounding cells, primary CD4(+) T cells were treated with cell-free supernatants from HTLV-I-infected MT-2 cell cultures. The primary CD4+ T cells became resistant to macrophage (M)-tropic HIV-1 but highly susceptible to T cell (T)-tropic HIV-1. The CC chemokines RANTES (regulated on activation, normal T cell expressed and secreted), macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta in the MT-2 cell supernatants were identified as the major suppressive factors for M-tropic HIV-1 as well as the enhancers of T-tropic HIV-1 infection, whereas soluble Tax protein increased susceptibility to both M- and T-tropic HIV-1. The effect of Tax or CC chemokines on T-tropic HIV-1 was mediated, at least in part, by increasing HIV Env-mediated fusogenicity. Our data suggest that the net effect of HTLV-I coinfection in HIV-infected individuals favors the transition from M- to T-tropic HIV phenotype, which is generally indicative of progressive HIV disease.