Human Immunodeficiency Virus Type-1 Infection of Human Myeloid Cells

Infection with human immunodeficiency virus type 1 (HIV-1) results in a wide range of immunologic and hematopoietic abnormalities. The overall goal of this dissertation was directed toward obtaining a better understanding of the interactions of HIV-1 and myeloid cells in relation to the pathogenesis of AIDS. The human myelomonocytic cell line, HL-60, was used as a model system to determine if HIV-1 infects myeloid progenitor cells and subsequently, if infection affects their differentiation. HL-60 cells and the human prototypic T cell line, H9 were infected with three different HIV-l isolates (IIIB, PM213, and NL4-3) which are known to infect T cells. All three isolates productively infected both H9 and HL-60 cells; however, HIV-1 antigen expression and cytopathicity was delayed by approximately 15 days in infected HL-60 cells compared H9 cells. To examine the effect of HIV-l infection on myeloid differentiation, chronically infected HL-60 cells and clonal lines derived from them were induced to differentiate into either granulocytes by treatment with dimethyl formamide (DMF) or into monocytes by treatment with phorbol l2-myristate 13 acetate (PMA). By both cellular morphology and function, approximately the same percentage of treated, HIV-infected HL-60 cells differentiated into either granulocytes or monocytes as treated, control HL-60 cells. Taken together, these results indicate that HIV-1 infection does not affect the morphological or functional differentiation of HL-60 cells. In an effort to understand the differences in the regulation of HIV-l infection in myeloid versus T cells, the life cycle of NL4-3 was examined in HL-60 cells and H9 cells. Initially, NL4-3 replication was restricted in HL-60 cells compared to H9 cells. This restriction was overcome 15 days after infection by the generation of a viral isolate, NL4-3(M). NL4-3(M), harvested during the lytic phase of NL4-3 infection of HL-60 cells, caused cell death approximately 8 days after infection in both H9 and HL-60 cells. Although measurements of viral entry kinetics demonstrated that the timing of entry of NL4-3 and NL4-3(M) in HL-60 cells and NL4-3 in H9 cells was similar, a quantitative polymerase chain reaction (PCR) analysis of newly reverse transcribed NL4-3 DNA in H9 and HL-60 cells revealed that NL4-3 infected H9 cells and NL4-3(M) infected HL-60 cells contain consistently higher amounts of newly reverse transcribed DNA than NL4-3 infected HL-60 cells. The delay in NL4-3 replication in HL-60 cells was further amplified by inefficient spread of the virus throughout the HL-60 culture as measured by RNA production and DNA integration suggesting that another step in the viral life cycle after reverse transcription was also restricted. These results suggest that the efficiency of NL43 replication in HL-60 cells is restricted at several steps in the viral life cycle. Further, these restrictions are overcome by the generation of a viral variant, NL4-3(M), which efficiently replicates in myeloid cells. The tropism of NL4-3(M) was further characterized by testing its growth in monocyte-derived macrophages (MDM). Unlike NL4-3, NL4-3(M) productively infected MDM cultures. The ability of NL4-3(M) to infect macrophages was conferred by the envelope gene. This was demonstrated by the ability of the recombinant virus, NL4-3envA, which contains the envelope of NL4-3(M) in the context of the NL4-3 genome, to infect and replicate in MDM cultures. The envelope gene of NL4-3(M), however, did not confer ability to rapidly kill HL-60 cells. Together, these findings demonstrate that viral determinants controlling entry into MDM are different trom the determinants controlling the cytopathic phenotype in HL-60 cells

T-cell development and function are modulated by dual specificity phosphatase DUSP5

Interleukin-2 (IL-2) is a pleiotropic cytokine that regulates lymphocyte proliferation and peripheral tolerance. IL-2 activates mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase, and signal transducer and activator of transcription (STAT) pathways and modulates expression of target genes. Systematic analysis of IL-2 target genes has revealed regulation of potential feedback inhibitors of IL-2 signaling, including several suppressor of cytokine signaling (SOCS) family members as well as MAPK pathway-regulating dual specificity phosphatases (DUSPs). Here we have evaluated the in vivo actions of DUSP5, an extracellular signal-regulated kinase 1/2 (ERK1/2)-specific phosphatase, by generating transgenic mice overexpressing DUSP5 within the lymphoid compartment. We show that transgenic DUSP5 expression results in a block in thymocyte development at the double positive stage. We also demonstrate that DUSP5-expressing mature T cells exhibit decreased IL-2-dependent proliferation and defective IL-2-mediated induction of genes. Finally, DUSP5 transgenic mice develop autoimmune symptoms, suggesting a role for the MAPK pathway in the regulation of tolerance. Thus, proper regulation of DUSP5 activity is critical for normal immune system development, IL-2 actions, and tolerance

A gene signature predicting for survival in suboptimally debulked patients with ovarian cancer

Despite the existence of morphologically indistinguishable disease, patients with advanced ovarian tumors display a broad range of survival end points. We hypothesize that gene expression profiling can identify a prognostic signature accounting for these distinct clinical outcomes. To resolve survival-associated loci, gene expression profiling was completed for an extensive set of 185 (90 optimal/95 suboptimal) primary ovarian tumors using the Affymetrix human U133A microarray. Cox regression analysis identified probe sets associated with survival in optimally and suboptimally debulked tumor sets at a P value of \u3c0.01. Leave-one-out cross-validation was applied to each tumor cohort and confirmed by a permutation test. External validation was conducted by applying the gene signature to a publicly available array database of expression profiles of advanced stage suboptimally debulked tumors. The prognostic signature successfully classified the tumors according to survival for suboptimally (P = 0.0179) but not optimally debulked (P = 0.144) patients. The suboptimal gene signature was validated using the independent set of tumors (odds ratio, 8.75; P = 0.0146). To elucidate signaling events amenable to therapeutic intervention in suboptimally debulked patients, pathway analysis was completed for the top 57 survival-associated probe sets. For suboptimally debulked patients, confirmation of the predictive gene signature supports the existence of a clinically relevant predictor, as well as the possibility of novel therapeutic opportunities. Ultimately, the prognostic classifier defined for suboptimally debulked tumors may aid in the classification and enhancement of patient outcome for this high-risk population