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Terri H Finkel

Publications and source records attributed to Terri H Finkel.

15 recordsLinked to original sources
PubMed2006

The Vif accessory protein alters the cell cycle of human immunodeficiency virus type 1 infected cells.

The viral infectivity factor gene (vif) of HIV-1 increases the infectivity of viral particles by inactivation of cellular anti-viral factors, and supports productive viral replication in primary human CD4 T cells and in certain non-permissive T cell lines. Here, we demonstrate that Vif also contributes to the arrest of HIV-1 infected cells in the G(2) phase of the cell cycle. Viruses deleted in Vif or Vpr induce less cell cycle arrest than wild-type virus, while cells infected with HIV-1 deleted in both Vif and Vpr have a cell cycle profile equivalent to that of uninfected cells. Furthermore, expression of Vif alone induces accumulation of cells in the G(2) phase of the cell cycle. These data demonstrate a novel role for Vif in cell cycle regulation and suggest that Vif and Vpr independently drive G(2) arrest in HIV-1 infected cells. Our results may have implications for the actions and interactions of key HIV-1 accessory proteins in AIDS pathogenesis.

Cell Cycle↗
PubMed2006

Effective gene suppression using small interfering RNA in hard-to-transfect human T cells.

RNA interference (RNAi) is an evolutionarily conserved cellular defense mechanism that protects cells from hostile genes and regulates the function of normal genes during growth and development. In this study, we established proof of principle of small interfering RNA (siRNA) silencing in hard-to-transfect human T cell lines and primary human CD4 T cells. We used public and in-house programs to design four siRNAs each for GFP, for our novel cellular gene HALP, and for their corresponding scrambled siRNA controls. We generated siRNA expression cassettes (SECs) by PCR and directly transfected the PCR products into T cells using amaxa Nucleofector technology. The most effective SECs were selected and cloned into a TA cloning vector and titered with their respective controls to increase transfection efficiency. Flow cytometry and fluorescence microscopy analyses were performed for GFP siRNAs, and Northern blot analysis was done to assess the HALP silencing effect. These experiments demonstrate that SECs are an excellent screening tool to identify siRNA sequences effective in silencing expression of genes of interest. The vector expressing the most effective siRNA robustly inhibited GFP expression (up to 92%) in the context of co-transfection in human T cell lines and primary CD4 T cells. The optimized siRNA for our endogenous cellular gene HALP also silenced its target RNA expression by more than 90%. These studies demonstrate that the combination of SEC, siRNA expression vectors and Nucleofector technology can be successfully applied to hard-to-transfect human T cell lines and primary T cells to effectively silence genes.

Asparaginase↗
PubMed2006

Early growth response-1 is required for CD154 transcription.

CD154 (CD40 ligand) expression on CD4 T cells is normally tightly controlled, but abnormal or dysregulated expression of CD154 has been well documented in autoimmune diseases, such as systemic lupus erythematosus. Beyond regulation by NFAT proteins, little is known about the transcriptional activation of the CD154 promoter. We identified a species-conserved purine-rich sequence located adjacent to the CD154 transcriptional promoter proximal NFAT site, which binds early growth response (Egr) transcription factors. Gel shift assays and chromatin immunoprecipitation assays reveal that Egr-1, Egr-3, and NFAT1 present in primary human CD4 T cells are capable of binding this combinatorial site in vitro and in vivo, respectively. Multimerization of this NFAT/Egr sequence in the context of a reporter gene demonstrates this sequence is transcriptionally active upon T cell activation in primary human CD4 T cells. Overexpression of Egr-1, but not Egr-3, is capable of augmenting transcription of this reporter gene as well as that of an intact CD154 promoter. Conversely, overexpression of small interfering RNA specific for Egr-1 in primary human CD4 T cells inhibits CD154 expression. Similarly, upon activation, CD154 message is notably decreased in splenic CD4 T cells from Egr-1-deficient mice compared with wild-type controls. Our data demonstrate that Egr-1 is required for CD154 transcription in primary CD4 T cells. This has implications for selective targeting of Egr family members to control abnormal expression of CD154 in autoimmune diseases such as systemic lupus erythematosus.

Animals↗
PubMed2006

Treatment of pediatric localized scleroderma with methotrexate.

OBJECTIVE: To analyze the effectiveness of methotrexate (MTX) for the therapy of pediatric localized scleroderma (LS). METHODS: A retrospective chart review was performed for 17 pediatric patients with LS who failed topical therapy and were subsequently treated with MTX (12.5-25 mg weekly) with or without oral corticosteroids. A structured followup telephone call to the families was used to assess patient satisfaction. RESULTS: Skin findings improved in 16 of 17 patients with a median time to improvement of 2.25 and 2.0 months for MTX alone or in combination with corticosteroids. Only one patient had active lesions at the most recent followup visit. Fifteen of 17 families reported improvement in their child's lesions after beginning MTX. Twelve of 17 patients were treated with MTX and oral corticosteroids. There were no major adverse events. CONCLUSION: MTX appears to be a safe and effective therapy for pediatric LS.

Adolescent↗
PubMed2005

Ligation of CD28 by its natural ligand CD86 in the absence of TCR stimulation induces lipid raft polarization in human CD4 T cells.

Stimulation of resting CD4 T cells with anti-CD3/CD28-coated beads leads to rapid polarization of lipid rafts (LRs). It has been postulated that a major role of costimulation is to facilitate LR aggregation. CD86 is up-regulated or expressed aberrantly on immune cells in a wide array of autoimmune and infectious diseases. Using an Ig fusion with the extracellular domain of CD86 (CD86Ig) bound to a magnetic bead or K562 cells expressing CD86, we demonstrated that ligation of CD28 by its natural ligand, but not by Ab, induced polarization of LRs at the cell-bead interface of fresh human CD4 T cells in the absence of TCR ligation. This correlated with activation of Vav-1, increase of the intracellular calcium concentration, and nuclear translocation of NF-kappaB p65, but did not result in T cell proliferation or cytokine production. These studies show, for the first time, that LR polarization can occur in the absence of TCR triggering, driven solely by the CD28/CD86 interaction. This result has implications for mechanisms of T cell activation. Abnormalities in this process may alter T and B cell tolerance and susceptibility to infection.

B7-2 Antigen↗
PubMed2005

The gammac-cytokine regulated transcription factor, STAT5, increases HIV-1 production in primary CD4 T cells.

Although HIV-1 (HIV) replicates poorly in non-dividing CD4 lymphocytes, resting T cells contribute to the latent reservoir. The gammac-related cytokines reverse this block to HIV infection; however, the molecular mechanisms controlling this process are not understood. We asked whether the gammac-cytokine regulated transcription factor, signal transducer and activator of transcription 5 (STAT5), activates HIV transcription. We identified three regions in the long terminal repeat (LTR) as close matches to the STAT5 consensus-binding site and show that STAT5 binds the LTR during HIV infection. Expression of Janus kinase 3 (JAK3) or STAT5 in primary human CD4 T cells activated LTR transcription, while transactivation-incompetent dominant-negative STAT5 inhibited JAK3-induced LTR activity and infection of activated HIV-producing CD4 T-cells. In addition, overexpression of STAT5 increased virus production in unstimulated primary T cells - both the number of p24+ cells and their level of p24 production - suggesting that STAT5 promotes a permissive state for HIV infection. These data may have implications for regulation of latency and therapeutic strategies for control of HIV disease.

Binding Sites↗
PubMed2004

Extensive replicative capacity of human central memory T cells.

To characterize the replicative capacity of human central memory (T(CM)) CD4 T cells, we have developed a defined culture system optimized for the ex vivo expansion of Ag-specific CD4(+) T cells. Artificial APCs (aAPCs) consisting of magnetic beads coated with Abs to HLA class II and a costimulatory Ab to CD28 were prepared; peptide-charged HLA class II tetramers were then loaded on the beads to provide Ag specificity. Influenza-specific DR*0401 CD4 T(CM) were isolated from the peripheral blood of normal donors by flow cytometry. Peptide-loaded aAPC were not sufficient to induce resting CD4 T(CM) to proliferate. In contrast, we found that the beads efficiently promoted the growth of previously activated CD4 T(CM) cells, yielding cultures with >80% Ag-specific CD4 cells after two stimulations. Further stimulation with peptide-loaded aAPC increased purity to >99% Ag-specific T cells. After in vitro culture for 3-12 wk, the flu-specific CD4 T(CM) had surface markers that were generally consistent with an effector phenotype described for CD8 T cells, except for the maintenance of CD28 expression. The T(CM) were capable of 20-40 mean population doublings in vitro, and the expanded cells produced IFN-gamma, IL-2, and TNF-alpha in response to Ag, and a subset of cells also secreted IL-4 with PMA/ionomycin treatment. In conclusion, aAPCs expand T(CM) that have extensive replicative capacity, and have potential applications in adoptive immunotherapy as well as for studying the biology of human MHC class II-restricted T cells.

Antigen-Presenting Cells↗
PubMed2004

Differential gene expression during HIV-1 infection analyzed by suppression subtractive hybridization.

OBJECTIVE: Characterization of the effects of HIV-1 infection and apoptosis on cellular and viral gene expression. METHODS: Flow cytometry was used to analyze infection and apoptosis concurrently in HIV-1IIIB-infected CEM-SS T cells. Suppression subtractive hybridization (SSH) was applied to cells from different time points of infection to construct subtracted complementary DNA (cDNA) libraries. Differential screening and Northern blots confirmed differential gene expression and these genes were sequenced and compared with database. RESULTS: T cells undergo apoptosis at early stages of HIV-1IIIB infection (days 5-7 post-infection). Surprisingly, cells begin to recover after day 9 and by day 18 almost all infected cells are viable, even though they maintain the same level of infection. By SSH, differential gene expression profiles between day 7 and day 18 after HIV-1IIIB infection were characterized. SSH yielded two subtracted cDNA libraries; differential screening of the subtracted cDNA libraries suggested that 200 out of 864 colonies were highly expressed at their respective time points. DNA sequence analysis identified specific apoptosis-related genes, HIV-1 viral genes, and other candidate genes of interest. Northern blot analysis confirmed that some of these genes were expressed predominantly at the 'apoptotic' or 'non-apoptotic' time points. CONCLUSIONS: Known and novel cellular gene products have been identified that are directly (or inversely) correlated with apoptosis and may regulate cell death in HIV-1 infection. These results provide a framework for functional studies on the differentially expressed genes and may suggest novel therapeutic approaches for treatment of HIV-1-infected individuals.

Apoptosis↗
PubMed2004

Chronic graft-versus-host reaction is associated with a decrease in Ig light chain receptor editing in bone marrow self-reactive B cells.

The encounter of developing B cells in the bone marrow with soluble hen egg lysozyme (sHEL) self antigen induces anergy and endogenous kappa light chain rearrangements ('receptor editing'). We have previously shown that induction of chronic graft-versus-host reaction (GVH) in tolerant Ig/sHEL mice results in prevention of B cell anergy in the bone marrow and the spleen. We now report that in chronic GVH, immature self-reactive B cells also show reduced levels of receptor editing in the bone marrow. This is evidenced by the following observations: (a) a small population of'receptor-edited' B cells, which is found in tolerant mice, is markedly reduced in mice that have lost tolerance in chronic GVH; (b) self-reactive B cells in GVH mice have reduced levels of endogenous kappa chain rearrangements; and (c) recombinase-activating gene (RAG)-2 expression is markedly decreased in immature self-reactive B cells in the bone marrow of chronic GVH mice. These results suggest that in chronic GVH newly emerging B cells escape tolerance, in part because of decreased receptor editing in the bone marrow. Thus, the autoimmunity induced by chronic GVH may ultimately result from the failure of B cell tolerance at multiple checkpoints.

Animals↗
PubMed2003

CXCR4 engagement is required for HIV-1-induced L-selectin shedding.

The chemokine receptor, CXCR4, serves as the primary coreceptor for entry of T-cell tropic human immunodeficiency virus (HIV). Binding of either the CXC-chemokine, stromal-derived factor 1 alpha (SDF-1 alpha), or a CXCR4 antagonist, AMD3100, to CXCR4 inhibits infection of CD4(+) T cells by T-tropic HIV-1, although only SDF-1 alpha triggers T-cell signaling cascades. We have previously demonstrated that ligation of CD4 by T-cell tropic HIV-1 NL4-3 induces metalloproteinase-dependent L-selectin (CD62L) shedding on resting CD4(+) T cells. However, the role of CXCR4 in HIV-induced L-selectin shedding is unclear. Here, we show that L-selectin shedding induced by HIV-1 NL4-3 is completely reversed by AMD3100, but not SDF-1 alpha, although SDF-1 alpha alone does not induce L-selectin shedding. These results indicate that engagement of both CD4 and CXCR4 is required for HIV-induced shedding of L-selectin on primary resting CD4(+) T cells.

CD4 Antigens↗
PubMed2003

Chronic GVH prevents anergy in bone marrow self-reactive B cells: a selective increase in post-endoplasmic reticulum processing and trafficking to the cell surface of autoreactive IgM receptors.

B cell autoreactivity is a component of chronic graft versus host (GVH) disease in humans and mice. Chronic GVH driven by I-A disparity results in loss of B cell tolerance in Ig/sHEL tolerant mice. In these mice, B cell anergy is characterized by down-modulation of sIgM mediated by intracellular retention in the endoplasmic reticulum (ER) and/or a block in post-ER processing of IgM receptors. Here, we report that GVH induces a selective increase in post-ER processing of the micro chain and trafficking to the cell surface of IgM receptors in B cells that bind HEL self-antigen. The increase in sIgM was detectable as early as 6 days post-GVH, before the appearance of circulating autoantibodies, and was particularly prominent in B cells that up-regulated surface I-A. A further increase in sIgM was found at later time points, along with circulating anti-HEL autoantibodies and a marked decrease in serum-free HEL, but no significant change in the amounts of HEL bound to B cells in vivo. These findings suggest that (i) abrogation of ER retention of IgM receptors in self-reactive B cells is an early event triggered by allogeneic T cells and (ii) at later stages of GVH disease the appearance of autoantibodies reduces the availability of free autoantigen, which may further escalate anergy escape of self-reactive B cells, and lead to exacerbation and perpetuation of autoimmunity.

Adoptive Transfer↗
PubMed2003

T cell signaling and apoptosis in HIV disease.

Groundbreaking research has led to an understanding of some of the pathogenic mechanisms of HIV-1 infection. Surprisingly, an unanswered question remains the mechanism(s) by which HIV-1 inactivates or kills T cells. Our goals are to define candidate T cell signaling cascades altered by HIV infection and to identify mechanisms whereby HIV-infected cells escape the apoptosis triggered by this aberrant signaling. In earlier work, we found that HIV reprograms healthy T cells to self-destruct by a process called apoptosis. We asked whether apoptosis occurs in organs of infected people and made a surprising discovery-this cell death occurs predominantly in healthy bystander cells and only rarely in infected cells. We hypothesize that HIV may be doubly diabolical-healthy T cells are killed in HIV infection, while infected cells resist killing. Thus, the virus protects its viral factory and allows HIV to turn the cell into a "Trojan Horse," with the virus in hiding or "latent." In this review, we discuss the role of viral and cellular proteins in HIV induced T cell anergy and death. We also discuss mechanisms by which HIV may protect infected T cells from apoptosis. These studies will yield new insights into the pathogenesis of AIDS, identify cellular targets that regulate HIV-1 infection, and suggest novel therapeutic approaches to cure HIV infection.

Animals↗
PubMed2002

Human CD8+ T cells do not require the polarization of lipid rafts for activation and proliferation.

Lipid rafts are important signaling platforms in T cells. Little is known about their properties in human CD8(+) T cells. We studied polarization of lipid rafts by digital immunofluorescence microscopy in primary human T cells, using beads coated with anti-CD3 and anti-CD28 mAbs (CD3/28 beads). Unlike CD4(+) T cells, CD8(+) T cells did not polarize lipid rafts when stimulated with CD3/28 beads, when the anti-CD28 antibody was substituted with B7.2Ig, or if an anti-CD8 antibody was added to the CD3/28 beads. This phenomenon was also observed in human antigen-specific CD8(+) T cells. On stimulation with CD3/28 beads, the T cell antigen receptor clustered at the cell/bead contact area in both CD4(+) and CD8(+) T cells. Examination of lipid rafts isolated by sucrose density gradient centrifugation revealed the constitutive expression of p(56)Lck in the raft fractions of unstimulated CD8(+) T cells, whereas p(56)Lck was recruited to the raft fraction of CD4(+) T cells only after stimulation with CD3/28 beads. Stimulation with CD3/28 beads induced marked calcium flux, recruitment of PKC-theta and F-actin to the cell/bead contact site, and similar proliferation patterns in CD4(+) and CD8(+) T cells. Thus, polarization of lipid rafts is not essential for early signal transduction events or proliferation of human CD8(+) lymphocytes. It is possible that the lower stringency of CD8(+) T cell activation obviates a requirement for raft polarization.

Antigens, CD↗
PubMed2002

Ligation of human CD4 interferes with antigen-induced activation of primary T cells.

The CD4 molecule functions to enhance T cell activation when it is co-aggregated with the T cell receptor for antigen (TCR) by MHC class II antigenic peptide complexes. However, independent ligation of CD4 has been shown to negatively effect signaling through the TCR in vitro. The interaction between the HIV-1 envelope glycoprotein gp120 and CD4 is a central event in the pathogenesis of AIDS and may contribute to immune deficiency via both direct and indirect mechanisms, including lytic infection of T cells and induction of CD4 signaling events resulting in apoptosis and anergy. Analysis of the consequences of interactions between CD4 and gp120 have yielded contradictory results presumably because most of these studies have focused on T cell clones of questionable relevance to the in vivo target of the virus. Here, we analyzed the effects of CD4 ligation on freshly isolated cells of human CD4 transgenic mice, and show that huCD4 preligation, in the absence of human CXCR4, has an inhibitory effect on both early and late T cell activation events. CD4 signaling negatively regulates the response to antigen, as well as to anti-TCR mAb. In addition, we show here that this negative signal requires the cytoplasmic tail of CD4. These results suggest that in HIV infected patients the interaction of gp120 with CD4 induces unresponsiveness of CD4+ T cells to subsequent activation by antigen.

Animals↗