Simian recombinant adenovirus delivered by the mucosal route modulates gammadelta T cells from murine genital tract

Double-edged sword: γδ T cells in mucosal homeostasis and disease

The mucosa is a tissue that covers numerous body surfaces, including the respiratory tract, digestive tract, eye, and urogenital tract. Mucosa is in direct contact with pathogens, and γδ T cells perform various roles in the tissue. γδ T cells efficiently defend the mucosa from various pathogens, such as viruses, bacteria, and fungi. In addition, γδ T cells are necessary for the maintenance of homeostasis because they select specific organisms in the microbiota and perform immunoregulatory functions. Furthermore, γδ T cells directly facilitate pregnancy by producing growth factors. However, γδ T cells can also play detrimental roles in mucosal health by amplifying inflammation, thereby worsening allergic responses. Moreover, these cells can act as major players in autoimmune diseases. Despite their robust roles in the mucosa, the application of γδ T cells in clinical practice is lacking because of factors such as gaps between mice and human cells, insufficient knowledge of the target of γδ T cells, and the small population of γδ T cells. However, γδ T cells may be attractive targets for clinical use due to their effector functions and low risk of inducing graft-versus-host disease. Therefore, robust research on γδ T cells is required to understand the crucial features of these cells and apply these knowledges to clinical practices.

Age-Related Changes in Female Murine Reproductive Mucosa with respect to γδ T Cell Presence

Many studies have demonstrated a general decline and dysregulation in immune functions with age. It is not clear, however, how the aging affects the immune surveillance of the female reproductive tract (FRT) by γδ T cells, a unique population of T lymphocytes that was shown to regulate homeostasis of epithelial barriers. First, we analyzed γδ T cell presence in FRT in young (2 months) and old (18 months) wild-type (WT) C57BL/6 mice. We did not detect any changes in γδ T cell number nor distribution in the vaginas between the age groups, while in uteri, there was a twofold increase in γδ T cell number in aged mice. To check if γδ T lymphocytes regulate a metabolic and immune status of aging vaginal tissue, we compared the expression of 84 aging-associated genes in young and old WT and γδ T-cell-deficient (Tcrd ^-/-) mice. We discovered that only the Ltf (lactotransferrin) gene was downregulated in old Tcrd ^-/- mice. In both mouse strains, we found similar age-dependent changes in cytokine production upon vaginal inflammation due to Toll-like receptor 9 (TLR9) stimulation with CpG. With age in the vaginas, IL-1α and IL-17A levels increased while IL-6, IL-10, MCP-1, and IFNγ levels were diminished in response to CpG. Similar trends were observed in uteri. Interestingly, under the inflammatory state, the lack of γδ T cells in young individuals enhanced MCP-1 production in the vagina and decreased MCP-1 level in the uterus in old females. Our gene expression data point to an antimicrobial role of γδ T lymphocytes. The profile of secreted inflammatory cytokines shifted during aging toward the proinflammatory type, and γδ T cells played a modest fine-tuning role in immunoregulation in aged FRT. We believe this work expands our understanding of γδ T cell functions and the inflammaging in the murine reproductive epithelia.

Impact of tissue enzymatic digestion on analysis of immune cells in mouse reproductive mucosa with a focus on γδ T cells

Mucosal tissues are enriched in γδ T lymphocytes, which maintain epithelial homeostasis, however, the homeostatic mechanisms are still incompletely understood. To elucidate their role in the tissue integrity governance within the female genital mucosa we employed flow cytometry, which is a powerful tool used for the characterization of tissue-resident immune cells, however, often requiring cell release upon tissue enzymatic disaggregation. Here, we analyzed the impact of various proteolytic enzymes in their ability to effectively isolate viable immune cells from the reproductive system of non-pregnant mice. Murine vaginas and uteri were digested using commercially available enzyme blends (liberases) and single enzymes (dispase II and collagenase IV). Among tested enzymes, liberases released the highest number of cells from digested tissues while dispase II and collagenase IV led to a significant decrease in the number of isolated live cells. Also, liberases had only minor detrimental effects on cell viability and detection of CD45, CD3ε, γδ TCR and CD11c positive cells. We found that a single liberase blend called Liberase TL was the most suited for the analysis of γδ T cells in the reproductive tract. By examining two distinct phases of the estrous cycle - estrus and diestrus, characterized by high and low epithelial stratification, respectively, we showed that higher numbers of γδ T lymphocytes were present in the latter cycle phase in vagina and uterus. Interestingly, the diestrus-associated increase in γδ T lymphocyte number was also observed in reproductive tract draining lumbar lymph nodes but not in more distant, inguinal lymph nodes. Our data indicate that enzymes used for reproductive mucosa digestion have profound effects on the cell viability and isolation efficiency, which consequently influence the phenotypic and quantitative analysis of immune cells.

Intravaginal Administration of Fc-Fused IL7 Suppresses the Cervicovaginal Tumor by Recruiting HPV DNA Vaccine-Induced CD8 T Cells

PURPOSE

The induction of tissue-localized virus-specific CD8 T-cell response is essential for the development of an effective therapeutic vaccine against genital diseases, such as cervical cancer and genital herpes. Here, we aimed to elucidate the immunologic role of IL7 in the induction of mucosal cellular immunity.

EXPERIMENTAL DESIGN

IL7 was engineered through Fc fusion to enhance mucosal delivery across the genital epithelial barrier. The immunomodulatory role of IL7 was evaluated by monitoring the kinetics of various immune cells and measuring the expression of chemokines and cytokines after intravaginal administration of Fc-fused IL7 (IL7-Fc). The antitumor effects of intramuscular human papillomavirus (HPV) DNA vaccine or topical IL7-Fc alone or in a combinational regimen on mice survival were compared using a orthotopic cervical cancer model.

RESULTS

Intravaginal treatment of IL7-Fc, but not native IL7, induces upregulation of chemokines (CXCL10, CCL3, CCL4, and CCL5), cytokines (IFNγ, TNFα, IL6, and IL1β), and an adhesion molecule (VCAM-1) in the genital tract, leading to the recruitment of several leukocytes, including CD4, CD8, γδ T cells, and dendritic cells. Importantly, in this murine cervical cancer model, topical administration of IL7-Fc after intramuscular HPV DNA vaccination increases the number of HPV-specific CD8 T cells in the genital mucosa, but not in the spleen, leading to stronger antitumor activity than the HPV DNA vaccine alone.

CONCLUSIONS

Our findings provide an important insight into the immunomodulatory role of IL7-Fc via topical application and the design of therapeutic vaccine regimen that induces effective genital-mucosal CD8 T-cell responses. Clin Cancer Res; 22(23); 5898-908. ©2016 AACR.

Intranasal delivery of Norwalk virus-like particles formulated in an in situ gelling, dry powder vaccine

The development of a vaccine to prevent norovirus infections has been focused on immunization at a mucosal surface, but has been limited by the low immunogenicity of self-assembling Norwalk virus-like particles (NV VLPs) delivered enterically or at nasal surfaces. Nasal immunization, which offers the advantage of ease of immunization, faces obstacles imposed by the normal process of mucociliary clearance, which limits residence time of applied antigens. Herein, we describe the use of a dry powder formulation (GelVac) of an inert in situ gelling polysaccharide (GelSite) extracted from Aloe vera for nasal delivery of NV VLP antigen. Powder formulations, with or without NV VLP antigen, were similar in structure in dry form or when rehydrated in simulated nasal fluids. Immunogenicity of the dry powder VLP formulation was compared to equivalent antigen/adjuvant liquid formulations in animals. For the GelVac powder, we observed superior NV-specific serum and mucosal (aerodigestive and reproductive tracts) antibody responses relative to liquid formulations. Incorporation of the TLR7 agonist gardiquimod in dry powder formulations did not enhance antibody responses, although its inclusion in liquid formulations did enhance VLP immunogenicity irrespective of the presence or absence of GelSite. We interpret these data as showing that GelSite-based dry powder formulations (1) stabilize the immunogenic structural properties of VLPs and (2) induce systemic and mucosal antibody titers which are equal or greater than those achieved by VLPs plus adjuvant in a liquid formulation. We conclude that in situ gelation of the GelVac dry powder formulation at nasal mucosal surfaces delays mucociliary clearance and thereby prolongs VLP antigen exposure to immune effector sites.