B-lymphocyte dysfunction in chronic HIV-1 infection does not prevent cross-clade neutralization breadth.

Aberrant expression of regulatory receptors programmed death-1 (PD-1) and B- and T-lymphocyte attenuator (BTLA) is linked with dysregulation and exhaustion of T lymphocytes during chronic human immunodeficiency virus type 1 (HIV-1) infection; however, less is known about whether a similar process impacts B-lymphocyte function during HIV-1 infection. We reasoned that disruption of the peripheral B cell compartment might be associated with decreased neutralizing antibody activity. Expression of markers that indicate dysregulation (BTLA and PD-1), immune activation (CD95), and proliferation (Ki-67) was evaluated in B cells from HIV-1-infected viremic and aviremic subjects and healthy subjects, in conjunction with immunoglobulin production and CD4 T cell count. Viral load and cross-clade neutralizing activity in plasma from viremic subjects were also assessed. Dysregulation of B lymphocytes was indicated by a marked disruption of peripheral B cell subsets, increased levels of PD-1 expression, and decreased levels of BTLA expression in viremic subjects compared to aviremic subjects and healthy controls. PD-1 and BTLA were correlated in a divergent fashion with immune activation, CD4 T cell count, and the total plasma IgG level, a functional correlate of B cell dysfunction. Within viremic subjects, the total IgG level correlated directly with cross-clade neutralizing activity in plasma. The findings demonstrate that even in chronically infected subjects in which B lymphocytes display multiple indications of dysfunction, antibodies that mediate cross-clade neutralization breadth continue to circulate in plasma.

Automated, quantitative screening assay for antiangiogenic compounds using transgenic zebrafish.

Pathologic angiogenesis has emerged as an important therapeutic target in several major diseases. Zebrafish offer the potential for high-throughput drug discovery in a whole vertebrate system. We developed the first quantitative, automated assay for antiangiogenic compound identification using zebrafish embryos. This assay uses transgenic zebrafish with fluorescent blood vessels to facilitate image analysis. We developed methods for automated drugging and imaging of zebrafish in 384-well plates and developed a custom algorithm to quantify the number of angiogenic blood vessels in zebrafish. The assay was used to screen the LOPAC1280 compound library for antiangiogenic compounds. Two known antiangiogenic compounds, SU4312 and AG1478, were identified as hits. Additionally, one compound with no previously known antiangiogenic activity, indirubin-3'-monoxime (IRO), was identified. We showed that each of the hit compounds had dose-dependent antiangiogenic activity in zebrafish. The IC(50) of SU4312, AG1478, and IRO in the zebrafish angiogenesis assay was 1.8, 8.5, and 0.31 micromol/L, respectively. IRO had the highest potency of the hit compounds. Moreover, IRO inhibited human umbilical vein endothelial cell tube formation and proliferation (IC(50) of 6.5 and 0.36 micromol/L, respectively). It is therefore the first antiangiogenic compound discovered initially in a zebrafish assay that also has demonstrable activity in human endothelial cell-based angiogenesis assays.