Biomedical subjects

A D Badley

Publications and source records attributed to A D Badley.

At least 19 recordsLinked to original sources

PubMed2005

In vitro and in vivo effects of HIV protease inhibitors on apoptosis.

Development of potent inhibitors of HIV protease has revolutionized the treatment of HIV infection. HIV protease inhibitors (PI) have caused more dramatic improvements in CD4 T-cell numbers than in other therapies that were available previously, prompting investigators to assess whether PI possess intrinsic immunomodulatory effects. An emerging body of data indicates that HIV PIs are antiapoptotic, although the exact molecular target responsible for this antiapoptotic effect remains to be defined in vitro and in vivo. Paradoxically, high-dose PI also may have proapoptotic effects, particularly when assessed in vitro in transformed cell lines and implanted mouse models. Future research will define molecular targets of PI that are responsible for their apoptotis modulatory effects (both pro- and anti-apoptotic). In addition, evaluation of the clinical utility of PI-based therapy in those non-HIV disease states that are characterized by excessive apoptotis will reveal the full clinical potential of this intriguing class of drugs.

Animals↗

PubMed2004

Antiretroviral therapy influences cellular susceptibility to apoptosis in vivo.

It has been proposed that antiretroviral therapies (ART) possess both antiviral and immunomodulatory activities when used in HIV infected patients. Few studies have addressed whether these putative immunomodulatory effects are also seen in HIV negative patients, for example, when used for post exposure prophylaxis (PEP). We chose to evaluate immunologic function in HIV negative patients who received Nelfinavir and Combivir (AZT and 3TC) as PEP. Lymphocytes from patients taken immediately before, during, and after PEP were analyzed. No changes were seen in absolute or percent CD4 or CD8 T lymphocyte numbers, nor in markers of activation, memory, or co-stimulatory molecules. Surface expression of apoptosis-related ligands and receptors were unaltered, but apoptosis susceptibility was significantly inhibited by PEP (P less than 0.05). These data confirm in vitro that apoptosis susceptibility is altered by ART, including in HIV-negative patients who take PEP.

Adult↗

PubMed2004

Cordyceps sinensis extracts do not prevent Fas-receptor and hydrogen peroxide-induced T-cell apoptosis.

Aqueous and alcohol extracts of Cordyceps sinensis (Berk) Succ. are used as a traditional medicine in China for the treatment of a wide range of diseases and are reported to have antioxidant and antiapoptotic properties. We therefore examined the ability of aqueous, organic, and alcohol extracts of Cordyceps sinensis to inhibit apoptosis induced either by hydrogen peroxide or Fas-receptor ligation; both stimuli induce apoptosis dependent on reactive oxygen species. Cells pre-incubated with Cordyceps sinensis extracts were equally sensitive to hydrogen peroxide and Fas-mediated apoptosis. Thus, the putative antioxidant and antiapoptotic properties of Cordyceps sinensis are insufficient to rescue cells from apoptosis induced by these stimuli in vitro.

Apoptosis↗

PubMed2002

Selection of lymphocyte gating protocol has an impact on the level of reliability of T-cell subsets in aging specimens.

BACKGROUND: In the past decade, human immunodeficiency virus (HIV) lymphocyte immunophenotyping has evolved significantly. New fluorochromes, new multicolor reagents, enhanced instruments, and the capacity to provide absolute cell counts using the single-platform technique have all contributed to the reliability of T-cell subset measurements. In this study, four gating protocols were evaluated to select the most robust method for T-cell subset enumeration. METHODS: Peripheral blood specimens from 21 HIV(+) and 20 HIV(-) individuals were monitored up to 96 h. Aliquots of specimens were stored at room temperature and analyzed at 6 (baseline), 48, 72, and 96 h. Aliquots were stained with CD45-fluorescein isothiocyanate (FITC)/CD3PC5/CD4RD1/CD8ECD. Data analysis was performed with all four gating protocols. RESULTS: Only with fresh blood did all protocols provide similar results. From samples that were 48 h old, the choice of gating strategy had a dramatic impact on immunophenotyping results. The largest deviations from baseline values occurred at 96 h and gating protocols that included dual light scatter gates provided the greatest shift of T-cell subset values over time. The gating protocols that were based exclusively on cell lineage-specific gates gave the most robust T-cell values up to 96 h. CONCLUSION: By selecting the appropriate gating protocol, the temporal integrity of specimens can be extended up to 4 days.

Acquired Immunodeficiency Syndrome↗

PubMed2002

Modulation of apoptosis by HIV protease inhibitors.

Advances in treatment have transformed the Human Immunodeficiency Virus (HIV) infection from a progressive and ultimately fatal disease to one that can be managed effectively by chronic suppressive antiretroviral therapy. The drugs now used to treat HIV infection not only inhibit viral replication but also have effects on cellular metabolism and homeostasis. Of particular interest to cellular immunologists, members of the HIV Protease Inhibitor (PI) class of antiretroviral agents possess intrinsic immunomodulatory and antiapoptotic properties. This review focuses on the development and use of PI together with their impact on HIV disease, immunity, and apoptosis.

Antiviral Agents↗

PubMed2002

HIV-1 protease processes procaspase 8 to cause mitochondrial release of cytochrome c, caspase cleavage and nuclear fragmentation.

Infection of T cells with HIV-1 induces apoptosis and modulates apoptosis regulatory molecules. Similar effects occur following treatment of cells with individual HIV-1 encoded proteins. While HIV-1 protease is known to be cytotoxic, little is known of its effect on apoptosis and apoptosis regulatory molecules. The ability of HIV-1 protease to kill cells, coupled with the degenerate substrate specificity of HIV-1 protease, suggests that HIV-1 protease may activate cellular factor(s) which, in turn, induce apoptosis. We demonstrate that HIV-1 protease directly cleaves and activates procaspase 8 in T cells which is associated with cleavage of BID, mitochondrial release of cytochrome c, activation of the downstream caspases 9 and 3, cleavage of DFF and PARP and, eventually, to nuclear condensation and DNA fragmentation that are characteristic of apoptosis. The effect of HIV-1 protease is not seen in T cell extracts which have undetectable levels of procaspase 8, indicating a specificity and requirement for procaspase 8.

Apoptosis↗

PubMed2002

Induction of apoptosis by a nonnucleoside human immunodeficiency virus type 1 reverse transcriptase inhibitor.

Inhibition of human immunodeficiency virus type 1 reverse transcriptase (RT) by both nucleoside and nonnucleoside RT inhibitors profoundly inhibits virus replication. Nucleoside RT inhibitors are known to be toxic, but there is little information regarding the toxicities of nonnucleoside RT inhibitors (NNRTI). We demonstrate that efavirenz (an NNRTI) induces caspase- and mitochondrion-dependent apoptosis of Jurkat T cells and human peripheral blood mononuclear cells. The clinical relevance of these observations is not yet clear.

Alkynes↗

PubMed2001

Poor CD4 T cell restoration after suppression of HIV-1 replication may reflect lower thymic function.

OBJECTIVE: To characterize immune phenotype and thymic function in HIV-1-infected adults with excellent virologic and poor immunologic responses to highly active antiretroviral therapy (HAART). METHODS: Cross-sectional study of patients with CD4 T cell rises of > or = 200 x 10(6) cells/l (CD4 responders; n = 10) or < 100 x 10(6) cells/l (poor responders; n = 12) in the first year of therapy. RESULTS: Poor responders were older than CD4 responders (46 versus 38 years; P < 0.01) and, before HAART, had higher CD4 cell counts (170 versus 35 x 106 cells/l; P = 0.11) and CD8 cell counts (780 versus 536 x 10(6) cells/l; P = 0.02). After a median of 160 weeks of therapy, CD4 responders had more circulating naive phenotype (CD45+CD62L+) CD4 cells (227 versus 44 x 10(6) cells/l; P = 0.001) and naive phenotype CD8 cells (487 versus 174 x 10(6) cells/l; P = 0.004) than did poor responders (after 130 weeks). Computed tomographic scans showed minimal thymic tissue in 11/12 poor responders and abundant tissue in 7/10 responders (P = 0.006). Poor responders had fewer CD4 cells containing T cell receptor excision circles (TREC) compared with CD4 responders (2.12 versus 27.5 x 10(6) cells/l; P = 0.004) and had shorter telomeres in CD4 cells (3.8 versus 5.3 kb; P = 0.05). Metabolic labeling studies with deuterated glucose indicated that the lower frequency of TREC-containing lymphocytes in poor responders was not caused by accelerated proliferation kinetics. CONCLUSION: Poor CD4 T cell increases observed in some patients with good virologic response to HAART may be caused by failure of thymic T cell production.

Adult↗

PubMed2001

Antiapoptotic mechanism of HIV protease inhibitors: preventing mitochondrial transmembrane potential loss.

Treatment of cells with the HIV drugs ritonavir, saquinavir, or nelfinavir (Nfv) inhibits apoptosis induced by a variety of stimuli. Because these drugs are protease inhibitors, they have been postulated to inhibit apoptosis by blocking caspase activity. This study shows that Nfv has no effect on caspase activity or on the transcription or synthesis of a variety of apoptosis regulatory molecules. Instead, Nfv inhibits mitochondrial transmembrane potential loss (Delta psi(m)) and the subsequent release of apoptotic mediators. Consequently, the antiapoptotic effects of Nfv are restricted to apoptotic pathways that involve Delta psi(m). (Blood. 2001;98:1078-1085)

Apoptosis↗

PubMed2001

Effect of cessation of highly active antiretroviral therapy during a discordant response: implications for scheduled therapeutic interruptions.

Although treatment with combination antiretroviral therapy leads to a reduction in the level of plasma viremia and an improvement in CD4 T cell count for most patients, for a minority of patients, an improvement in CD4 T cell count occurs despite the failure of treatment to suppress viral replication. Recent reports suggest that these discordant improvements in CD4 T cell count may last for months to years and are associated with improved clinical outcomes. In a retrospective observational study, we evaluated the effect of therapy cessation on 8 patients with discordant immunologic responses to therapy and found that improved CD4 T cell responses are dependent upon ongoing drug pressure. If antiretroviral agents that are likely to resuppress the virus are not available, we suggest that patients continue the therapy associated with immunologic improvement to maximize the clinical benefit of the discordant response.

Adult↗

PubMed2001

Progressive human immunodeficiency virus-specific immune recovery with prolonged viral suppression.

The degree of immune recovery achievable with anti-human immunodeficiency virus (HIV) therapy remains to be established. The effects of potent antiretroviral therapy, including ritonavir and saquinavir, on immune function were studied for a prolonged period in 41 patients. After 96 weeks, 88% of patients had plasma HIV RNA levels below the limit of quantitation. There were continuous increases in CD4 lymphocyte counts and in CD4:CD8 ratios over time. About half the patients developed lymphoproliferative responses to HIV p24 antigen, and nearly all developed responses to phytohemagglutinin. This occurred in parallel with increases in interleukin-12 production and expression of CD28 on CD8 lymphocytes, despite potential antiproliferative effects of protease inhibitors. Transient increases in virus load were temporally associated with loss of proliferative responses. The improved immune function, including HIV-specific immunity in many subjects, demonstrates the potential reversibility of HIV-induced immunodeficiency and does not identify a limit to immune recovery.

Anti-HIV Agents↗

PubMed2001

Modulation of HIV transcription by CD8(+) cells is mediated via multiple elements of the long terminal repeat.

HIV replication and LTR-mediated gene expression can be modulated by CD8(+) cells in a cell type-dependent manner. We have previously shown that supernatant fluids of activated CD8(+) cells of HIV-infected individuals suppress long terminal repeat (LTR)-mediated transcription of HIV in T cells while enhancing transcription in monocytic cells. Here, we have examined the effect of culture of T cells and monocytic cells with CD8(+) supernatant fluids, and subsequent binding of transcription factors to the HIV-1 LTR. In transfections using constructs in which NF kappa B or NFAT-1 sites were mutated, the LTR retained the ability to respond positively to culture with CD8 supernatant fluid in monocytic cells. Nuclear extracts prepared from both Jurkat T cells and U38 monocytic cells cultured with CD8(+) cell supernatant fluid demonstrated increased binding to the HIV-1 LTR at an AP-1 site which overlapped the chicken ovalbumin upstream promoter (COUP) site. In monocytic cells, increased binding activity was observed at the NF kappa B sites of the LTR. In contrast, an inhibition in binding at the NF kappa B sites was observed in Jurkat cells. Examination of two NFAT-1 sites revealed enhanced binding at - 260 to - 275 bp in U38 cells which was reduced by cellular activation. PMA and ionomycin-induced binding at a second NFAT-1 site (- 205 to - 216 bp) was abrogated by CD8(+) cell supernatant fluid in T cells. These results, taken together, suggest that factors present in CD8(+) supernatant fluids may act through several sites of the LTR to modulate transcription in a cell type-dependent manner.

CD8-Positive T-Lymphocytes↗

PubMed2001

Induction of cell death in human immunodeficiency virus-infected macrophages and resting memory CD4 T cells by TRAIL/Apo2l.

Because the persistence of human immunodeficiency virus (HIV) in cellular reservoirs presents an obstacle to viral eradication, we evaluated whether tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2L) induces apoptosis in such reservoirs. Lymphocytes and monocyte-derived macrophages (MDM) from uninfected donors do not die following treatment with either leucine zipper human TRAIL (LZhuTRAIL) or agonistic anti-TRAIL receptor antibodies. By contrast, such treatment induces apoptosis of in vitro HIV-infected MDM as well as peripheral blood lymphocytes from HIV-infected patients, including CD4(+) CD45RO(+) HLA-DR(-) lymphocytes. In addition, LZhuTRAIL-treated cells produce less viral RNA and p24 antigen than untreated controls. Whereas untreated cultures produce large amounts of HIV RNA and p24 antigen, of seven treated CD4(+) CD45RO(+) HLA-DR(-) cell cultures, viral RNA production was undetectable in all, p24 antigen was undetectable in six, and proviral DNA was undetectable in four. These data demonstrate that TRAIL induces death of cells from HIV-infected patients, including cell types which harbor latent HIV reservoirs.

Antiretroviral Therapy, Highly Active↗

PubMed2000

Mechanisms of HIV-associated lymphocyte apoptosis.

Infection with the human immunodeficiency virus (HIV) is associated with a progressive decrease in CD4 T-cell number and a consequent impairment in host immune defenses. Analysis of T cells from patients infected with HIV, or of T cells infected in vitro with HIV, demonstrates a significant fraction of both infected and uninfected cells dying by apoptosis. The many mechanisms that contribute to HIV-associated lymphocyte apoptosis include chronic immunologic activation; gp120/160 ligation of the CD4 receptor; enhanced production of cytotoxic ligands or viral proteins by monocytes, macrophages, B cells, and CD8 T cells from HIV-infected patients that kill uninfected CD4 T cells; and direct infection of target cells by HIV, resulting in apoptosis. Although HIV infection results in T-cell apoptosis, under some circumstances HIV infection of resting T cells or macrophages does not result in apoptosis; this may be a critical step in the development of viral reservoirs. Recent therapies for HIV effectively reduce lymphoid and peripheral T-cell apoptosis, reduce viral replication, and enhance cellular immune competence; however, they do not alter viral reservoirs. Further understanding the regulation of apoptosis in HIV disease is required to develop novel immune-based therapies aimed at modifying HIV-induced apoptosis to the benefit of patients infected with HIV.

Apoptosis↗

PubMed2000

Flow cytometric measurement of telomere length.

The regulation of telomere length may be involved in the cellular physiology of senescence, reproduction, cancer, immune response to infection, and possibly immune deficiency. The measurement of telomere length, critical to research in this area, has traditionally been performed by Southern blot analysis, which is cumbersome and time consuming. Several alternative methods have been described in recent years. Some, such as pulsed-field electrophoresis, slot blots, and centromere-to-telomere ratio measurements are essentially improvements to the Southern blot technique. However, other methods such as fluorescent in situ hybridization on metaphase chromosome spreads and flow cytometry-based fluorescent in situ hybridization represent a completely new technical approach to the problem. In this review, we compare methods, with particular emphasis placed on flow cytometric techniques for measuring telomere length in situ and identifying potential areas where improvements may still be made.

Animals↗

PubMed2000

Decreased HIV-associated T cell apoptosis by HIV protease inhibitors.

Antiretroviral treatment of patients infected with HIV results in improvements in CD4+ T cell number. Emerging evidence suggests that some of the improvements in CD4+ T cell number that occur in response to protease inhibitor (PI) therapy may not be accounted for solely by enhanced viral suppression, implying that PI may directly affect T cell survival. Since HIV T cell depletion is associated with enhanced apoptosis, we analyzed the effect of PIs on T cell apoptosis. In vitro treatment of peripheral blood lymphocytes (PBLs) from HIV-infected but untreated patients with reverse transcriptase inhibitors (RTIs) does not alter apoptosis, whereas PI treatment rapidly reduces CD4+ and CD8+ T cell apoptosis. In contrast, PI treatment does not alter apoptosis in PBL blasts from HIV-negative patients, or in Jurkat T cells. Consistent with this observation, 8 days of PI therapy in HIV-infected patients does not significantly alter plasma viremia, yet results in significant inhibition of CD4+ and CD8+ T cell apoptosis. The inhibitory effects of PI on apoptosis have implications concerning the treatment of HIV and its pathogenesis.

Apoptosis↗

PubMed2000

The economic impact of cytomegalovirus infection after liver transplantation.

BACKGROUND: We studied the economic impact of cytomegalovirus (CMV) disease and its effective reduction with antiviral prophylaxis in liver transplant recipients. METHOD: Analysis of institutional charge data accumulated during a prospective, randomized, controlled trial comparing oral acyclovir 800 mg four times daily for 120 days (ACV) and intravenous ganciclovir 5 mg/kg every 12 h for 14 days followed by ACV for 106 days (GCV) was performed. RESULTS: Liver transplant recipients who developed CMV disease had significantly higher charges (median: $148,300) than those who developed asymptomatic CMV infection ($119,600) or experienced no CMV infection ($114,100) (P<0.01). A multiple linear regression analysis indicated that CMV disease is associated with a 49% increase in charges, independent of other factors influencing increased hospitalization charges. In CMV-seronegative patients who received a CMV-seropositive donor organ, GCV prophylaxis was associated with a significant reduction in charges, as compared to ACV prophylaxis ($113,900 vs. $153,300, respectively; P=0.02). CONCLUSIONS: CMV disease is an independent risk factor for increased resource utilization associated with liver transplantation. The use of an effective prophylactic antiviral regimen provides savings in health care resources, particularly in patients at high risk for developing CMV disease.

Administration, Oral↗

PubMed1999

Activation-induced CD4+ T cell death in HIV-positive individuals correlates with Fas susceptibility, CD4+ T cell count, and HIV plasma viral copy number.

The relevance of activation-induced cell death (AICD) of CD4+ T cells to AIDS pathogenesis is unknown. The present study investigates the relationship of AICD to a defined molecular mechanism regulating peripheral T cell homeostasis, Fas-mediated apoptosis, and clinical correlates of the pathogenesis of AIDS. Increased pokeweed mitogen (PWM)-induced AICD (22.8 versus 4.4%, p = 0.006) and Fas-mediated apoptosis (27.7 versus 12.0%, p = 0.002) of CD4+ T cells were observed in HIV+ versus HIV- individuals. Similarly, increased PWM-mediated AICD (16.2 versus 2.2%, p < 0.001) and Fas-mediated apoptosis (25.8 versus 7.6%, p = 0.005) were noted in CD8+ T cells from HIV+ versus HIV- individuals. PWM-induced AICD of CD4+ T cells was blocked (83% median specific inhibition) by Fas-blocking antibodies, whereas PWM-induced AICD of CD8+ T cells was Fas independent. Comparison between PWM- and anti-CD3-mediated AICD of CD4+ T cells indicated that PWM- and not CD3-induced AICD is Fas dependent. HIV+ individuals with an HIV RNA copy number of <30,000 copies/ml had lower PWM-induced AICD of CD4+ T cells than did those with an HIV RNA copy number of >30,000 copies/ml (5.7 versus 22.1%, p = 0.034), and PWM-induced AICD inversely correlated with CD4+ T cell count (R = -0.567, p = 0.043). Initiation of HAART decreased PWM-induced CD4+ T cell AICD from 24.4 to 9.4% posttreatment (p = 0.035). These results demonstrate that PWM-induced AICD of CD4+ T cells from HIV+ individuals is mediated by Fas/FasL, parallels the in vivo susceptibility of the CD4+ T cell to Fas-mediated apoptosis, and correlates with clinical markers of AIDS pathogenesis and response to HAART.

Anti-HIV Agents↗