Deborah M. Brown

Human Papillomavirus Virus-Like Particles Are Efficient Oral Immunogens when Coadministered with Escherichia coli Heat-Labile Enterotoxin Mutant R192G or CpG DNA

ABSTRACT Certain human papillomaviruses (HPVs) cause most cervical cancer, which remains a significant source of morbidity and mortality among women worldwide. HPV recombinant virus-like particles (VLPs) are promising vaccine candidates for controlling anogenital HPV disease and are now being evaluated as a parenteral vaccine modality in human subjects. Vaccines formulated for injection generally are more costly, more difficult to administer, and less acceptable to recipients than are mucosally administered vaccines. Since oral delivery represents an attractive alternative to parenteral injection for large-scale human vaccination, the oral immunogenicity of HPV type 11 (HPV-11) VLPs in mice was previously investigated; it was found that a modest systemic neutralizing antibody response was induced (R. C. Rose, C. Lane, S. Wilson, J. A. Suzich, E. Rybicki, and A. L. Williamson, Vaccine 17:2129–2135, 1999). Here we examine whether VLPs of other genotypes may also be immunogenic when administered orally and whether mucosal adjuvants can be used to enhance VLP oral immunogenicity. We show that HPV-16 and HPV-18 VLPs are immunogenic when administered orally and that oral coadministration of these antigens with Escherichia coli heat-labile enterotoxin (LT) mutant R192G (LT R192G) or CpG DNA can significantly improve anti-VLP humoral responses in peripheral blood and in genital mucosal secretions. Our results also suggest that LT R192G may be superior to CpG DNA in this ability. These findings support the concept of oral immunization against anogenital HPV disease and suggest that clinical studies involving this approach may be warranted.

A molecular analysis of PGE receptor (EP) expression on normal and transformed B lymphocytes: Coexpression of EP1, EP2, EP3β and EP4

The E-series prostaglandins (PGEs) are complex lipid regulators of B lymphocyte function. They inhibit the growth of certain B lymphoma lines. We report that heterogeneity with respect to PGE-induced growth inhibition correlates with the maturation state of the B cell lines. Specifically, the pre-B cell line 70Z/3 and the immature lymphoma CH31 are extremely sensitive to PGE2. To a lesser degree, other immature lymphomas (CH33, ECH408.1 and WEHI-231) are sensitive to PGE2. More mature lymphomas (BAL-17, CH12 and CH27) and fully differentiated myelomas (J558 and MOPC-315) are insensitive to PGE2. It is unknown what subtype of PGE receptor(s) (EPs) are expressed by B lymphocytes. It is also unknown if modulation of EP receptor expression could account for the differences in the sensitivity of these B cell lines to PGE2. To investigate these issues, reverse transcriptase polymerase chain reaction, Northern blot and DNA sequencing analyses were employed to obtain a definitive EP receptor subtype profile for these B cell lines, and for normal splenic B lymphocytes. Both normal and transformed B lymphocytes express mRNA encoding EP1, EP3beta and EP4 subtypes of PGE receptors. The B lineage cells do not express EP3alpha nor EP3gamma mRNA. The B cell lines are clonal, indicating that EP1, EP3beta and EP4 mRNA are coexpressed. Surprisingly, quantitative differences in basal EP1, EP3beta and EP4 expression were not observed between B cell lines despite their differing susceptibilities to PGE-induced growth inhibition. Conversely, the polyclonal activator LPS selectively upregulates EP4 mRNA expression in the mature B cell line CH12, but not in the LPS-sensitive pre-B cell line, 70Z/3. The activator LPS does not affect EP1 nor EP3beta mRNA expression. Treatment with dbcAMP, an analog of cAMP, mimics PGE-induced growth inhibition indicating that Gs-coupled EP2 and/or EP4 receptors mediate this inhibitory signal. Indeed, EP2 agonists mimic PGE2-induced growth inhibition unlike IP, EP1 and EP3-selective agonists. These data indicate that EP2 receptors are sufficient for mediating PGE-induced growth inhibition of susceptible B lineage cells.

PGE2 Regulation of B Lymphocytes and T Helper 1 and T Helper 2 Cells: Induction of Inflammatory versus Allergic Responses

Immunoglobulin E (IgE) and T-helper type 2 (Th2) cytokines mediate many traits of allergic disease. Therefore, understanding regulation of these responses is critical for comprehending disease pathogenesis and for developing effective therapies. Numerous mechanisms regulate IgE and Th2 cytokine production, however, an emerging concept is that E-series prostaglandins (PGEs), shift the immune response towards allergy by promoting production of IgE and a Th2 profile of cytokines (1). PGEs are lipid molecules which regulate diverse processes throughout the body. Low levels of PGEs are constantly produced in most tissues by “constitutive” cyclooxygenases (COX-1), (2). In response to hormonal or inflammatory stimuli, PGEs are also synthesized by “inducible” cyclooxygenases (COX-2), (2). Of particular importance, PGEs are a major product of professional antigen presenting cells such as, macrophages, follicular dendritic cells and Langerhans cells (1, 2). PGEs are also produced by other APCs such as, fibroblasts and endothelial cells in response to inflammatory stimuli (2). PGEs promote IgE and Th2 responses at multiple levels. Firstly, PGEs induce development of Th2 cells via modulating cytokine production by antigen presenting cells. Secondly, PGEs inhibit Th1 and promote Th2 profiles of cytokine production from mature differentiated T cells. Finally, PGEs directly target B lymphocytes and enhance cytokine-directed recombination of the Ig heavy chain loci.