Biomedical subjects

William Harrington

Publications and source records attributed to William Harrington.

6 recordsLinked to original sources

PubMed2006

KSHV/HHV-8 infection of human hematopoietic progenitor (CD34+) cells: persistence of infection during hematopoiesis in vitro and in vivo.

The cellular reservoir for Kaposi sarcoma-associated herpesvirus (KSHV) infection in the hematopoietic compartment and mechanisms governing latent infection and reactivation remain undefined. To determine susceptibility of human CD34+ hematopoietic progenitor cells (HPCs) to infection with KSHV, purified HPCs were exposed to KSHV, and cells were differentiated in vitro and in vivo. Clonogenic colony-forming activity was significantly suppressed in KSHV-infected CD34+ cells, and viral DNA was predominantly localized to granulocyte-macrophage colonies differentiated in vitro. rKSHV.219 is a recombinant KSHV construct that expresses green fluorescent protein from a cellular promoter active during latency and red fluorescent protein from a viral lytic promoter. Infection of CD34+ HPCs with rKSHV.219 showed similar patterns of infection, persistence, and hematopoietic suppression in vitro in comparison with KSHV. rKSHV.219 infection was detected in human CD14+ and CD19+ cells recovered from NOD/SCID mouse bone marrow and spleen following reconstitution with rKSHV.219-infected CD34+ HPCs. These results suggest that rKSHV.219 establishes persistent infection in NOD/SCID mice and that virus may be disseminated following differentiation of infected HPCs into the B-cell and monocyte lineages. CD34+ HPCs may be a reservoir for KSHV infection and may provide a continuous source of virally infected cells in vivo.

Animals↗

PubMed2005

Inhibition of HHV-8/KSHV infected primary effusion lymphomas in NOD/SCID mice by azidothymidine and interferon-alpha.

Kaposi's sarcoma-associated herpesvirus/human herpesvirus type-8 (KSHV/HHV-8) is associated with primary effusion lymphomas (PEL), a rare form of B-cell lymphoma. PEL cell lines infected with HHV-8, but negative for Epstein-Barr virus (EBV), were analyzed for their tumorigenic potential in a small animal model system. Inoculation of PEL cell lines into non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice results in efficient engraftment and tumorigenesis in vivo. PEL-engrafted NOD/SCID (PEL/SCID) mice displayed malignant ascites development with notable abdominal distension, consistent with the clinical manifestations of PEL in humans. Azidothymidine (AZT, zidovudine) and interferon-alpha (IFN-alpha) induce apoptosis in HHV-8+/EBV- PEL cells in culture, by induction of a tumor necrosis factor-related apoptosis inducing ligand (TRAIL) mediated suicide program and has been proposed as a therapy for herpesvirus-associated lymphomas. Daily injection of AZT and IFN-alpha significantly increased mean survival time (MST) of PEL/SCID mice suggesting that induction of apoptosis in PEL cells in vivo may be exploited as an effective relatively non-toxic therapy targeting HHV-8 infected PEL. These data demonstrate that the PEL/SCID mouse is an important preclinical model to characterize efficacy and anti-tumor mechanisms of new therapeutic targets in vivo and will be useful in the design and testing of agents in viral lymphoproliferative diseases.

Animals↗

PubMed2005

Intestinal strongyloidiasis: recognition, management, and determinants of outcome.

Significant advances have occurred in our understanding of the biology, immunology, and immunopathology of the usually asymptomatic human infection by the intestinal parasite, Strongyloides stercoralis. Factors that increase the risk for the occurrence of symptomatic intestinal hyperinfection and/or often-fatal disseminated strongyloidiasis have been better defined. The pathophysiology underlying these risk factors, whether disease-related or iatrogenically induced, is a compromised immune system leading to dysfunction of TH-2 helper cells. These specialized lymphocytes are central to maintaining the delicate balance that exists between the infected human host and the stabilized parasite. Recognition of risk factors that impair the function of TH-2 lymphocytes is essential to heightening the index of clinical suspicion enhancing earlier, accurate diagnosis, and the introduction of appropriate therapy. This review summarizes what is understood about infection by S. stercoralis; its focus will be on the epidemiology, diagnosis, clinical presentation patterns in the immunocompetent and immunocompromised human hosts, and recommended treatment regimens.

Humans↗

PubMed2005

Modulation of human herpesvirus 8/Kaposi's sarcoma-associated herpesvirus replication and transcription activator transactivation by interferon regulatory factor 7.

Human herpesvirus 8 (HHV-8)/Kaposi's sarcoma-associated herpesvirus infection goes through lytic and latent phases that are regulated by viral gene products, but very little is known about the involvement of host proteins. The replication and transcription activator (RTA) is a viral protein sufficient to initiate lytic replication by activating downstream genes, including the viral early gene open reading frame 57 (ORF 57), which codes for a posttranscriptional activator. In this study, we demonstrate that cellular interferon regulatory factor 7 (IRF-7) negatively regulates this process by competing with RTA for binding to the RTA response element in the ORF 57 promoter to down-regulate RTA-induced gene expression. We also show that alpha interferon represses RTA-mediated transactivation and that repression involves IRF-7. Our study indicates that upon HHV-8 infection, the host responds by suppression of lytic gene expression through binding of IRF-7 to the lytic viral gene promoter. These findings suggest that HHV-8 has developed a novel mechanism to induce but then subvert the innate antiviral response, specifically the interferon-signaling pathway, to regulate RTA activity and ultimately the viral latent/lytic replicative cycle.

DNA-Binding Proteins↗

PubMed2002

Multicenter trial of low-dose paclitaxel in patients with advanced AIDS-related Kaposi sarcoma.

BACKGROUND: Treatment options are limited for patients with advanced acquired immunodeficiency syndrome (AIDS)-related Kaposi sarcoma (AIDS-KS) whose disease has progressed after receiving therapy with liposomal anthracyclines or combination chemotherapy with doxorubicin (Adriamycin), bleomycin, and vincristine (ABV). This study was performed to assess the safety and efficacy of a novel dose and schedule of paclitaxel in patients with AIDS-KS who failed to respond to previous systemic chemotherapy. METHODS: This was an open-label, multicenter Phase II study. Eligible patients had advanced AIDS-KS consisting of at least 25 mucocutaneous lesions, visceral disease, or lymphedema, and had failed to respond to at least one previous systemic chemotherapy regimen. Patients were treated with paclitaxel at a dose of 100 mg/m(2) given intravenously over 3 hours, every 2 weeks. Primary efficacy end points were tumor response, time to progression, time to treatment failure, and survival. Quality of life and adverse events were evaluated using the Symptom Distress Scale (SDS) and the World Health Organization Toxicity Criteria, respectively. RESULTS: One hundred and seven male patients with advanced AIDS-KS were enrolled from nine participating sites. The median entry CD4+ lymphocyte count was 41/mm(3) (range 0-1139). Previous treatment regimens included ABV in 52, liposomal daunorubicin in 49, and liposomal doxorubicin in 40 patients. Forty-one patients (38%) received two or more previous chemotherapy regimens. Protease inhibitor use during the study was reported by 82 (77%) patients overall; 47 patients (44%) were receiving a protease inhibitor before study entry. Complete or partial response was documented in 60 patients (56%). The median duration of response was 8.9 months. Major response rate was similar when comparing patients not on a protease inhibitor at the time of response (59%) with patients on a protease inhibitor at time of response (54%). However, protease inhibitor use had a significant impact on survival (P = 0.04). Grade 4 neutropenia was reported in 35% of patients; other life-threatening side effects were uncommon. Significant improvements were seen in the total quality of life scores measured by the SDS, including significant improvement in KS-related symptoms such as facial disease, tumor-associated edema, and pulmonary involvement. CONCLUSION: Paclitaxel given every 2 weeks induces major tumor regression in the majority of patients with advanced KS who failed to respond to previous systemic chemotherapy. Paclitaxel is associated with significant improvement in quality of life with acceptable toxicity and should be considered as an effective treatment option for patients with advanced KS.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

AIDS and associated malignancies.

AIDS associated malignancies (ARL) is a major complication associated with AIDS patients upon immunosuppression. Chronically immunocompromised patients have a markedly increased risk of developing lymphoproliferative disease. In the era of potent antiretrovirals therapy (ARV), the malignant complications due to HIV-1 infection have decreased in developed nations where ARV is administered, but still poses a major problem in developing countries where HIV-1 incidence is high and ARV is still not yet widely available. Even in ARV treated individuals there is a concern that the prolonged survival of many HIV-1 carriers is likely to eventually result in an increased number of malignancies diagnosed. Malignancies that were found to have high incidence in HIV-infected individuals are Kaposi's sarcoma (KS), Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL). The incidence of NHL has increased nearly 200 fold in HIV-positive patients, and accounts for a greater percentage of AIDS defining illness in the US and Europe since the advent of HAART therapy. These AIDS related lymphomas are distinct from their counterparts seen in HIV-1 seronegative patients. For example nearly half of all cases of ARL are associated with the presence of a gamma herpesvirus, Epstein Barr virus (EBV) or human herpesvirus-8 (HHV-8)/ Kaposi's sarcoma associated herpesvirus (KSHV). The pathogenesis of ARLs is complex. B-cell proliferation driven by chronic antigenemia resulting in the induction of polyclonal and ultimately monoclonal lymphoproliferation may occur in the setting of severe immunosuppression.

Acquired Immunodeficiency Syndrome↗