Intravaginal Immunization of Mice with Recombinant Salmonella enterica Serovar Typhimurium Expressing Human Papillomavirus Type 16 Antigens as a Potential Route of Vaccination against Cervical Cancer

Abstract

Cervical cancer, the second leading cause of cancer deaths in women, is the consequence of high-risk human papillomavirus (HPV) infections. Toward the development of therapeutic vaccines that can induce both innate and adaptive mucosal immune responses, we analyzed intravaginal (ivag) vaccine delivery of live attenuated Salmonella enterica serovar Typhimurium expressing HPV16L1 as a model antigen. Innate immune responses were examined in cervicovaginal tissues by determining gene expression patterns by microarray analysis using nylon membranes imprinted with cDNA fragments coding for inflammation-associated genes. At 24 h, a wide range of genes, including those for chemokines and Th1-and Th2-type cytokine and chemokine receptors were up-regulated in mice ivag immunized with Salmonella compared to control mice. However, the majority of transcripts returned to their steady-state levels 1 week after immunization, suggesting a transient inflamma- Cervical cancer is the second leading cause of cancer deaths among women worldwide, with half a million new cases per year, of which 83% occur in developing countries (54). Cervical cancer is caused by infection with a subset of human papillomavirus (HPV), of which type 16 is found most frequently (62). HPV vaccines based on highly purified virus-like particles (VLP) from HPV have been shown to be safe, highly immunogenic, and effective in preventing the development of HPV16 and -18 infections and associated cervical neoplasia (53, 70). However, these prophylactic vaccines can only prevent ca. 70% of all cervical cancers if administered to young adolescents before sexual activity. During the decades necessary to implement prophylactic strategies, millions of women will be or have already been infected by HPVs and may develop associated malignant lesions that could be treated by therapeutic vaccines. Up to now, different therapeutic vaccines, usually targeting the HPV E6 and/or E7 oncogenes and administered parenterally, have shown only limited clinical success (39). Cell-mediated immune responses are important in controlling both HPV infections and HPV-associated neoplasms, as shown by the increased prevalence of these diseases when impaired cell-mediated immunity occurs, such as in transplant recipients or in human immunodeficiency virus-infected patients (38,61,63). The immunosuppressive microenvironment of the cervical mucosa favors the development of high-grade squamous intraepithelial lesions and/or cervical cancer, which correlates with local type II cytokines (24), absence of gamma interferon (IFN-␥) (23), and reduced density and function of Langerhans cells (25), as well as an increased proportion of regulatory T cells in the draining lymph nodes of cervical cancer patients (17, 67). In addition, there is little or no inflammation at the site of primary HPV infection and HPV may be able to suppress the host immune response (35), in particular, type 16, which was recently shown to down-regulate the expression of Toll-like receptor 9 (TLR9) in human primary keratinocy...

Flagellin from Recombinant Attenuated Salmonella enterica Serovar Typhimurium Reveals a Fundamental Role in Chicken Innate Immunity

“…A previous study reported an upregulation in both IL-1 and IFN-␥ mRNAs in the Peyer's patches and mesenteric lymph nodes in mice following immunization with attenuated Salmonella constructs at day 7 (23). Similarly, Echchannaoui et al (12) showed that a wide range of genes, including those for chemokines and Th1-and Th2-type cytokines, were upregulated in mice immunized with live attenuated recombinant S. Typhimurium strains compared to control mice at day 1. In contrast, Trebichavsky et al (46) found that attenuated aroA S. Typhimurium did not induce IL-1␤, IL-18, TNF-␣, or IFN-␥ in the ileum and plasma in gnotobiotic pigs at 24 h after the infection.…”

Oral Immunization with RecombinantLactobacillus plantarumInduces a Protective Immune Response in Mice with Lyme Disease

“…Throughout the immunization regimen, stool samples were collected on days 0, 2,4,7,9,11,14,28,30,32,34,49,51,53, and 55 to determine the viability of L. plantarum and its ability to colonize the digestive tract. Suspensions of stools collected from mice immunized with LpA or LpA␣ contained on average 10 6 cells/g of luminal contents, in contrast to the control.…”

“…Mucosal vaccines using commensal bacteria rely on its endogenous regulation being transferred to the vaccine antigen (40). Vaccines based on attenuated bacterial pathogens, especially live Salmonellabased oral vaccines, have demonstrated the ability to induce protective mucosal and systemic immune responses (6,14,52,61,63). However, public fear of using an attenuated pathogen as a vaccine carrier has deterred its acceptance.…”

Oral Vaccination with AttenuatedSalmonella entericaStrains Encoding T-Cell Epitopes from Tumor Antigen NY-ESO-1 Induces Specific Cytotoxic T-Lymphocyte Responses

“…It has been clearly established that the use of attenuated Salmonella strains as live oral vaccines is a safe and effective means of inducing significant humoral and secretory antibody responses in animal species, including humans and mice (8,16,21,(32)(33)(34). The use of plasmid-based expression systems to elevate foreign antigen levels in Salmonella live vaccine vectors is ideal, but these systems have the serious disadvantages of instability and selective requirements in vivo (10,14,17,38).…”