Biomedical subjects

Todd J Suscovich

Publications and source records attributed to Todd J Suscovich.

9 recordsLinked to original sources

PubMed2006

Low perforin and elevated SHIP-1 expression is associated with functional anergy of natural killer cells in chronic HIV-1 infection.

Natural killer (NK) cells are critical for the first-line defense in infection. Treated viremic HIV-1 infection is associated with the expansion of an anergic subset of CD3-CD56-CD16+ NK cells unable to respond to stimulation with MHC-devoid target cells or with mitogens. These CD3-CD56-CD16+ NK cells expressed SHIP-1 and had significantly reduced perforin levels. This observation suggests a mechanism for the reduced functional activity of CD3-CD56-CD16+ NK cells in chronic HIV-1 infection.

Chronic Disease↗

PubMed2005

Alpha E beta 7 (CD103) expression identifies a highly active, tonsil-resident effector-memory CTL population.

The characterization of antiviral CTL responses has largely been limited to assessing Ag-specific immune responses in the peripheral blood. Consequently, there is an incomplete understanding of the cellular immune responses at mucosal sites where many viruses enter and initially replicate and how the Ag specificity and activation status of CTL derived from these mucosal sites may differ from that of blood-derived CTL. In this study, we show that EBV-specific CTL responses in the tonsils are of comparable specificity and breadth but of a significantly higher magnitude compared with responses in the peripheral blood. EBV-specific, tonsil-resident, but not PBMC-derived, T cells expressed the integrin/activation marker CD103 (alphaEbeta7), consistent with the detection of its ligand, E-cadherin, on tonsillar squamous cells. These CD8-positive, CD103-positive, tonsil-derived CTL were largely CCR7- and CD45RA- negative effector-memory cells and responded to lower Ag concentrations in in vitro assays than their CD103-negative PBMC-derived counterparts. Thus, EBV-specific CTL in the tonsil, a crucial site for EBV entry and replication, are of greater magnitude and phenotypically distinct from CTL in the peripheral blood and may be important for effective control of this orally transmitted virus.

Antigens, Viral↗

PubMed2005

Differential targeting and shifts in the immunodominance of Epstein-Barr virus--specific CD8 and CD4 T cell responses during acute and persistent infection.

The evolution of Epstein-Barr virus (EBV)-specific T cell responses that occurs during the acute and persistent stages of infection remains poorly characterized despite its importance for developing immune interventions for EBV-associated disorders. This study assessed T cell responses to 113 EBV-derived epitopes in 40 subjects with acute or persistent EBV infection. Although no significant differences were seen in the breadth of CD8 and CD4 T cell responses, their magnitude differed significantly over time; acutely infected subjects generated especially strong responses to lytic viral antigens. The cross-sectional shift in immunodominance was also confirmed in subjects followed longitudinally from acute to persistent infection. In addition, human leukocyte antigen-matched siblings with discordant histories of symptomatic EBV infection showed no significant differences in their response patterns, suggesting that symptomatic EBV infection does not lead to unique persistent-stage responses. These data provide an assessment of immunodominance patterns and guidance for developing immunotherapeutic interventions for EBV-associated disorders.

Amino Acid Sequence↗

PubMed2005

Impact of Kaposi sarcoma-associated herpesvirus (KSHV) burden and HIV coinfection on the detection of T cell responses to KSHV ORF73 and ORF65 proteins.

Cellular immune responses to Kaposi sarcoma-associated herpesvirus (KSHV), the etiological agent of KS and several other malignancies, are incompletely characterized. We assessed KSHV-specific interferon- gamma enzyme-linked immunospot responses in a cohort of 154 individuals, using overlapping peptide sets spanning the KSHV-encoded latency-associated nuclear antigen (ORF73) and the minor capsid glycoprotein (ORF65). Among KSHV-seropositive subjects, ORF73-specific responses dominated over responses to ORF65 and were preferentially detected in human immunodeficiency virus-coinfected individuals who had elevated levels of cell-associated KSHV DNA, indicating that the viral antigen burden may have been driving these responses. Responses to both ORF73 and ORF65 were also detected in several KSHV-seronegative subjects who were at increased risk for KSHV infection, which demonstrates that cellular immunity can be found in the absence of detectable humoral responses. These data have implications for the reliable identification of KSHV infection and may help guide the design of immune-based therapeutic and prophylactic interventions.

Antigens, Viral↗

PubMed2005

Sequential deregulation of NK cell subset distribution and function starting in acute HIV-1 infection.

Natural killer (NK) cells are critical in the first-line defense against viral infections. Chronic HIV-1 infection leads to a perturbation in the NK cell compartment, yet the kinetics of this deregulation and the functional consequences are unclear. Here, we characterized changes in the NK cell compartment longitudinally by multiparameter flow cytometry, starting in acute HIV-1 infection. Acute HIV-1 infection was associated with elevated NK cell numbers, with an expansion of CD3(neg)CD56(dim)CD16(pos) NK cells and an early depletion of CD3(neg)CD56(bright)CD16(neg) NK cells. Ongoing viral replication resulted in a depletion of CD3(neg)CD56(dim)CD16(pos) NK cells with a paralleled increase in functionally anergic CD3(neg)CD56(neg)CD16(pos) NK cells, accompanied by reduced functional activity, as measured by CD107a expression and cytokine secretion. Taken together, these studies demonstrate a sequential impairment of NK cell function with persistent viral replication resulting from a progressive deregulation of NK cell subsets with distinct functional properties.

Acute Disease↗

PubMed2005

Simultaneous assessment of cytotoxic T lymphocyte responses against multiple viral infections by combined usage of optimal epitope matrices, anti- CD3 mAb T-cell expansion and "RecycleSpot"

The assessment of cellular anti-viral immunity is often hampered by the limited availability of adequate samples, especially when attempting simultaneous, high-resolution determination of T cell responses against multiple viral infections. Thus, the development of assay systems, which optimize cell usage, while still allowing for the detailed determination of breadth and magnitude of virus-specific cytotoxic T lymphocyte (CTL) responses, is urgently needed. This study provides an up-to-date listing of currently known, well-defined viral CTL epitopes for HIV, EBV, CMV, HCV and HBV and describes an approach that overcomes some of the above limitations through the use of peptide matrices of optimally defined viral CTL epitopes in combination with anti-CD3 in vitro T cell expansion and re-use of cells from negative ELISpot wells. The data show that, when compared to direct ex vivo cell preparations, antigen-unspecific in vitro T cell expansion maintains the breadth of detectable T cell responses and demonstrates that harvesting cells from negative ELISpot wells for re-use in subsequent ELISpot assays (RecycleSpot), further maximized the use of available cells. Furthermore when combining T cell expansion and RecycleSpot with the use of rationally designed peptide matrices, antiviral immunity against more than 400 different CTL epitopes from five different viruses can be reproducibly assessed from samples of less than 10 milliliters of blood without compromising information on the breadth and magnitude of these responses. Together, these data support an approach that facilitates the assessment of cellular immunity against multiple viral co-infections in settings where sample availability is severely limited.

Journal Article↗

PubMed2004

Heat shock protein-mediated cross-presentation of exogenous HIV antigen on HLA class I and class II.

Strong CD4(+) and CD8(+) T cell responses are considered important immune components for controlling HIV infection, and their priming may be central to an effective HIV vaccine. We describe in this study an approach by which multiple CD4(+) and CD8(+) T cell epitopes are processed and presented from an exogenously added HIV-1 Gag-p24 peptide of 32 aa complexed to heat shock protein (HSP) gp96. CD8(+) T cell recognition of the HSP/peptide complex, but not the peptide alone, was inhibited by brefeldin A, suggesting an endoplasmic reticulum-dependent pathway. This is the first report to describe efficient processing and simultaneous presentation of overlapping class I- and class II-restricted epitopes from the same extracellularly added precursor peptide complexed to HSP. Given previous reports of the strong immunogenicity of HSP/peptide complexes, the present data suggest that HSP-complexed peptides containing multiple MHC class I- and class II-restricted epitopes represent potential vaccine candidates for HIV and other viral infections suitable to induce effective CTL memory by simultaneously providing CD4 T cell help.

AIDS Vaccines↗

PubMed2004

Defective immune function of primary effusion lymphoma cells is associated with distinct KSHV gene expression profiles.

Primary effusion lymphomas (PEL) are uniformly infected with Kaposi's sarcoma-associated herpesvirus (KSHV), and thus likely present both tumor and viral antigens to the immune system. In order to grow unrestricted and cause disease, multiple immune evasion strategies may be utilized by PEL to evade immune surveillance. Using six well-established PEL cell lines and comparing these to Epstein-Barr virus-transformed B cell lines and peripheral blood B cells, significant differences were found in the surface expression of molecules involved in antigen presentation, T cell activation and cell-cell adhesion. Significantly reduced stimulation of cytotoxic T lymphocytes, lowered sensitivity to natural killer cell-mediated lysis and impaired function as antigen presenting cells in mixed leukocyte reactions were found for three PEL cell lines with particularly low CD54, CD58 and CD81 expression. Comparative microarray analysis demonstrated specific patterns of KSHV-encoded gene expression that were associated with the different immune functions of these cell lines. Thus, the present data suggest that distinct patterns of KSHV gene expression may be associated with particular phenotypic and functional characteristics of PEL cells, which may influence PEL pathogenesis.

Adult↗

PubMed2003

Tissue distribution of liposome-mediated epidermal growth factor receptor antisense gene therapy.

Despite the widespread use of liposome-mediated gene transfer in cancer therapy protocols, little is known about the tissue distribution of intralesionally administered DNA. We have previously shown that antisense gene therapy targeting the epidermal growth factor receptor (EGFR) inhibited tumor growth in a human head and neck squamous cell carcinoma (HNSCC) xenograft model. Further investigation demonstrated lack of systemic toxicity with intramuscular or intratumoral administration of this liposomal-DNA complex. In the present study, we compared two approaches to determine the presence of exogenous DNA in the plasma and tissues of mice treated with intramuscular injection of EGFR antisense gene therapy. PCR analysis using genomic DNA plus plasmid DNA as template was 83-fold more sensitive than PCR using a mixture of total RNA and plasmid DNA as template. With the more sensitive method (able to detect fewer than 500 molecules of EGFR antisense DNA in 1 microg of genomic DNA), foreign DNA was detected in all organs up to 1 month following a single injection. In contrast, using RNA plus plasmid DNA as template, exogenous DNA was only detected at the injection site at 1 week, and was undetectable at 1 month. Optical imaging studies demonstrated plasmid DNA only at the injection site. Although less sensitive than PCCR, Southern blot hybridization showed no evidence of integration of foreign DNA into the host genome in vitro or in vivo. These results emphasize the importance of defining the assays used to detect foreign DNA and suggest that the ability to detect intralesionally administered liposomal gene therapy, in organs distant from the injection site, is directly correlated with the sensitivity of the method employed.

Animals↗