Antigen recognition in the female reproductive tract: I. Uptake of intraluminal protein tracers in the mouse vagina

Boosting of vaginal HSV-2-specific B and T cell responses by intravaginal therapeutic immunization results in diminished recurrent HSV-2 disease

Boosting herpes simplex virus (HSV)-specific immunity in the genital tissues of HSV-positive individuals to increase control of HSV-2 recurrent disease and virus shedding is an important goal of therapeutic immunization and would impact HSV-2 transmission. Experimental therapeutic HSV-2 vaccines delivered by a parenteral route have resulted in decreased recurrent disease in experimental animals. We used a guinea pig model of HSV-2 infection to test if HSV-specific antibody and cell-mediated responses in the vaginal mucosa would be more effectively increased by intravaginal (Ivag) therapeutic immunization compared to parenteral immunization. Therapeutic immunization with HSV glycoproteins and CpG adjuvant increased glycoprotein-specific IgG titers in vaginal secretions and serum to comparable levels in Ivag- and intramuscular (IM)-immunized animals. However, the mean numbers of HSV glycoprotein-specific antibody secreting cells (ASCs) and IFN-γ SCs were greater in Ivag-immunized animals demonstrating superior boosting of immunity in the vaginal mucosa compared to parenteral immunization. Therapeutic Ivag immunization also resulted in a significant decrease in the cumulative mean lesion days compared to IM immunization. There was no difference in the incidence or magnitude of HSV-2 shedding in either therapeutic immunization group compared to control-treated animals. Collectively, these data demonstrated that Ivag therapeutic immunization was superior compared to parenteral immunization to boost HSV-2 antigen-specific ASC and IFN-γ SC responses in the vagina and control recurrent HSV-2 disease. These results suggest that novel antigen delivery methods providing controlled release of optimized antigen/adjuvant combinations in the vaginal mucosa would be an effective approach for therapeutic HSV vaccines. IMPORTANCE HSV-2 replicates in skin cells before it infects sensory nerve cells where it establishes a lifelong but mostly silent infection. HSV-2 occasionally reactivates, producing new virus which is released back at the skin surface and may be transmitted to new individuals. Some HSV-specific immune cells reside at the skin site of the HSV-2 infection that can quickly activate and clear new virus. Immunizing people already infected with HSV-2 to boost their skin-resident immune cells and rapidly control the new HSV-2 infection is logical, but we do not know the best way to administer the vaccine to achieve this goal. In this study, a therapeutic vaccine given intravaginally resulted in significantly better protection against HSV-2 disease than immunization with the same vaccine by a conventional route. Immunization by the intravaginal route resulted in greater stimulation of vaginal-resident, virus-specific cells that produced antibody and produced immune molecules to rapidly clear virus.

Mucosal Vaccine Approaches for Prevention of HIV and SIV Transmission

Optimal protective immunity to HIV will likely require that plasma cells, memory B cells and memory T cells be stationed in mucosal tissues at portals of viral entry. Mucosal vaccine administration is more effective than parenteral vaccine delivery for this purpose. The challenge has been to achieve efficient vaccine uptake at mucosal surfaces, and to identify safe and effective adjuvants, especially for mucosally administered HIV envelope protein immunogens. Here, we discuss strategies used to deliver potential HIV vaccine candidates in the intestine, respiratory tract, and male and female genital tract of humans and nonhuman primates. We also review mucosal adjuvants, including Toll-like receptor agonists, which may adjuvant both mucosal humoral and cellular immune responses to HIV protein immunogens.

Seminal fluid and reproduction: much more than previously thought

The influence of seminal plasma on the cytokine and immune uterine environment is well characterised in mice and humans, while the effects of disruption to uterine seminal plasma exposure on pregnancy and offspring health is becoming more clearly understood. The cellular and molecular environment of the uterus during the pre- and peri-implantation period of early pregnancy is critical for implantation success and optimal foetal and placental development. Perturbations to this environment not only have consequences for the success of pregnancy and neonatal health and viability, but can also drive adverse health outcomes in the offspring after birth, particularly the development of metabolic disorders such as obesity, hypertension and insulin resistance. It is now reported that an absence of seminal plasma at conception in mice promotes increased fat accumulation, altered metabolism and hypertension in offspring. The evidence reviewed here demonstrates that seminal plasma is not simply a transport medium for sperm, but acts also as a key regulator of the female tract environment providing optimal support for the developing embryo and benefiting future health of offspring.

Nanoparticle transport from mouse vagina to adjacent lymph nodes

To test the feasibility of localized intravaginal therapy directed to neighboring lymph nodes, the transport of quantum dots across the vaginal wall was investigated. Quantum dots instilled into the mouse vagina were transported across the vaginal mucosa into draining lymph nodes, but not into distant nodes. Most of the particles were transported to the lumbar nodes; far fewer were transported to the inguinal nodes. A low level of transport was evident at 4 hr after intravaginal instillation, and transport peaked at about 36 hr after instillation. Transport was greatly enhanced by prior vaginal instillation of Nonoxynol-9. Hundreds of micrograms of nanoparticles/kg tissue (ppb) were found in the lumbar lymph nodes at 36 hr post-instillation. Our results imply that targeted transport of microbicides or immunogens from the vagina to local lymph organs is feasible. They also offer an in vivo model for assessing the toxicity of compounds intended for intravaginal use.

Effective vaginal DNA delivery with high transfection efficiency is a good system for induction of higher local vaginal immune responses

Objectives

To investigate the local vaginal and systemic immune responses of effective vaginal DNA delivery with high transfection efficiency, we determined the effects on Th1-dependent cytokine (interferon-γ) production in spleen and inguinal lymph node cells and antibody responses of vaginal pDNA immunization with a cell-penetrating peptide, and compared our vaginal immunization with intradermal and intranasal immunizations.

Methods

Mice were immunized by vaginal, nasal or dermal administration of pCMV-OVA with or without peptide carriers, and serum, vaginal fluids, spleen and inguinal cells were harvested. The serum immunoglobulin (Ig)G2a and vaginal IgA antibody responses were determined by sandwich enzyme-linked immunosorbent assay (ELISA). The interferon-γ production from spleen cells or inguinal lymph node cells was determined by an ELISA kit.

Key findings

The direct vaginal immunization strongly induced IgA in the vaginal fluids and interferon-γ production in the local lymph node draining from the vagina. In addition, co-vaccination with the peptide carriers elevated these immune responses compared with vaccination with pCMV-OVA alone. Vaginal immunization with high transfection efficiency promoted vaginal IgA production to a significantly greater extent than intradermal or nasal immunization.

Conclusions

These results suggested that direct vaginal DNA vaccines under high transfection conditions induced higher local vaginal antibody than that by intranasal or intradermal administration, and peptide carriers effectively elevated mucosal immune responses. Therefore, this vaginal DNA vaccination method may be expected to be useful in the prevention and treatment methods for vaginal infectious diseases such as HIV infection.

Immunopathogenesis of recurrent genital candidosis in women

Introduction. There are more and more women that suffer from chronic recurrent genital candidiasis. At the beginning of the research in this field the researchers usually studied the properties of the microorganism then nonspecific resistance of the vaginal mucosa, possibility of endogenous and exogenous reinfection, hormonal status of women in order to determine the cause of the recurrent genitall candidosis. After numerous studies, only the risk factors were determined, but not the very cause of the recurrence of this fungal infection. The following investigation encompassed examination of the immunity of the vaginal mucosa, as welll as the influence of the system cellular immunity to the course of the vaginal fungal infection. Results of those studies show that neither hyporeactivity, nor the disregulation of the system cellular immunity has influence to the course of the recurrent genital candidosis. Conclusion. Based on the existence of the antigen presenting cells and phenotypically different T- lymphocytes in the vaginal mucosa, it was determined that this mucous membrane represents immunocompetent tissue, and accordingly, one may assume that the cause of the recurrent genital candidosis may lie in disregulation of the local immune response to the Candida sp. antigens.

Regulatory T cells are locally induced during intravaginal infection of mice with Neisseria gonorrhoeae

Neisseria gonorrhoeae is a gram-negative diplococcus that in human beings produces gonorrhea. Much clinical evidence has led to the conclusion that gonococcus has important mechanisms to evade host immune functions; however, these mechanisms are only now beginning to be elucidated. In this study, we determined that the BALB/c mouse is a good animal model to study gonococcus infection and examined the immune response against the bacteria. We determined that after intravaginal inoculation of mice with Neisseria gonorrhoeae, the bacteria reached and invaded the upper female reproductive tissues and elicited a T-cell-specific immune response associated with a very weak humoral response, altogether resembling gonococcus infection and disease in women. Remarkably, in the draining lymph nodes of the genital tracts of infected mice, we found an increase of regulatory T lymphocytes, namely, transforming growth factor beta1-positive CD4(+) T cells and CD4(+) CD25(+) Foxp3(+) T cells. Altogether, results indicate that N. gonorrhoeae induces regulatory T cells, which might be related to the local survival of the pathogen and the establishment of a chronic asymptomatic infection.

Chlamydia trachomatis infection: host immune responses and potential vaccines

Chlamydia trachomatis causes genital tract infections that affect men, women, and children on a global scale. This review focuses on innate and adaptive immune responses in the female reproductive tract (FRT) to genital tract infections with C. trachomatis. It covers C. trachomatis infections and highlights our current knowledge of genital tract infections, serovar distribution, infectious load, and clinical manifestations of these infections in women. The unique features of the immune system of the FRT will be discussed and will include a review of our current knowledge of innate and adaptive immunity to chlamydial infections at this mucosal site. The use of animal models to study the pathogenesis of, and immunity to, Chlamydia infection of the female genital tract will also be discussed and a review of recent immunization and challenge experiments in the murine model of chlamydial FRT infection will be presented.

Immune-mediated control of Chlamydia infection

Infection with the bacterium Chlamydia trachomatis can lead to a variety of diseases, including ectopic pregnancy, infertility and blindness. Exposure of the host to C. trachomatis stimulates multiple innate and adaptive immune effectors that can contribute towards controlling bacterial replication. However, these effectors are often insufficient to resolve the infection and prevent re-infection, and the continued presence of C. trachomatis within the host may induce immune effectors to chronically produce inflammatory cytokines. This may eventually lead to the tissue pathologies associated with the infection. Reducing the incidence and sequelae of infection will ultimately require the development of a C. trachomatis vaccine that can stimulate sterilizing immunity while avoiding immune-mediated pathology.

Mucosal dendritic cells

The internal surfaces of the human body are covered by distinct types of epithelial cells and mucus-secreting cells. The mucosal surfaces serve many vital functions, such as respiration (nasal passage and lung), absorption (gastrointestinal tract), excretion (lung, urinary tract, large intestine), and reproduction (reproductive tract). In performing these functions, the host is inevitably exposed to environmental antigens, food particles, commensal flora, and pathogens. Mucosal surfaces contain specialized dendritic cells (DCs) capable of sensing these external stimuli and mounting appropriate local responses depending on the nature of the elements they encounter. In the absence of pathogens, mucosal DCs either ignore the antigen or induce regulatory responses. Upon recognition of microorganisms that invade the mucosal barrier, mucosal DCs mount robust protective immunity. This review highlights progress in our understanding of how mucosal DCs process external information and direct appropriate responses by mobilizing various cells of the innate and adaptive immune systems to achieve homeostasis and protection.

Monitoring the T cell response to genital tract infection

To date, it has not been possible to study antigen-specific T cell responses during primary infection of the genital tract. The low frequency of pathogen-specific T cells in a naïve mouse makes it difficult to monitor the initial events after antigen encounter. We developed a system to examine the response of pathogen-specific T cells in the genital mucosa after intrauterine infection. We identified the protective CD4(+) T cell antigen Cta1 from Chlamydia trachomatis and generated T cell receptor (TCR) transgenic (tg) mice with specificity for this protein. By transferring TCR tg T cells into naïve animals, we determined that Chlamydia-specific T cells were activated and proliferated in the lymph nodes draining the genital tract after primary intrauterine infection. Activated T cells migrated into the genital mucosa and secreted IFN-gamma. The development of Chlamydia-specific TCR tg mice provides an approach for dissecting how pathogen-specific T cells function in the genital tract.

Enhanced mucosal delivery of antigen with cell wall mutants of lactic acid bacteria

The potential of recombinant lactic acid bacteria (LAB) to deliver heterologous antigens to the immune system and to induce protective immunity has been best demonstrated by using the C subunit of tetanus toxin (TTFC) as a model antigen. Two types of LAB carriers have mainly been used, Lactobacillus plantarum and Lactococcus lactis, which differ substantially in their abilities to resist passage through the stomach and to persist in the mouse gastrointestinal tract. Here we analyzed the effect of a deficiency in alanine racemase, an enzyme that participates in cell wall synthesis, in each of these bacterial carriers. Recombinant wild-type and mutant strains of L. plantarum NCIMB8826 and L. lactis MG1363 producing TTFC intracellularly were constructed and used in mouse immunization experiments. Remarkably, we observed that the two cell wall mutant strains were far more immunogenic than their wild-type counterparts when the intragastric route was used. However, intestinal TTFC-specific immunoglobulin A was induced only after immunization with the recombinant L. plantarum mutant strain. Moreover, the alanine racemase mutant of either LAB strain allowed induction of a much stronger serum TTFC-specific immune response after immunization via the vagina, which is a quite different ecosystem than the gastrointestinal tract. The design and use of these mutants thus resulted in a major improvement in the mucosal delivery of antigens exhibiting vaccine properties.

In vivo role of nectin-1 in entry of herpes simplex virus type 1 (HSV-1) and HSV-2 through the vaginal mucosa

Herpes simplex virus type 2 (HSV-2) is transmitted through the genital mucosa during sexual encounters. In recent years, HSV-1 has also become commonly associated with primary genital herpes. The mechanism of viral entry of HSV-1 and HSV-2 in the female genital tract is unknown. In order to understand the molecular interactions required for HSV entry into the vaginal epithelium, we examined the expression of herpesvirus entry mediator nectin-1 in the vagina of human and mouse at different stages of their hormonal cycle. Nectin-1 was highly expressed in the epithelium of human vagina throughout the menstrual cycle, whereas the mouse vaginal epithelium expressed nectin-1 only during the stages of the estrous cycle in which mice are susceptible to vaginal HSV infection. Furthermore, the ability of nectin-1 to mediate viral entry following intravaginal inoculation was examined in a mouse model of genital herpes. Vaginal infection with either HSV-1 or HSV-2 was blocked by preincubation of the virus with soluble recombinant nectin-1. Viral entry through the vaginal mucosa was also inhibited by preincubation of HSV-2 with antibody against gD. Together, these results suggest the importance of nectin-1 in mediating viral entry for both HSV-1 and HSV-2 in the genital mucosa in female hosts.

The role of dendritic cells in immune responses against vaginal infection by herpes simplex virus type 2

Herpes simplex virus type 2 is a leading cause of genital ulcers that affects more women than men worldwide. Recent evidence indicates that protective immunity can be generated by specialized dendritic cells in the female genital mucosa. This article aims to provide an overview of the effector immunity required for protection from genital herpes, and to discuss the mechanism by which specific subsets of dendritic cells mediate induction of adaptive immunity following genital infection with herpes simplex virus type 2 in vivo.

Mucosal immunization with inactivated HIV-1-capturing nanospheres induces a significant HIV-1-specific vaginal antibody response in mice

Mucosal secretory IgA is considered to have an important role in the prevention of human immunodeficiency virus type 1 (HIV-1) transmission through sexual intercourse. Therefore, substances that induce HIV-1-specific IgA antibody in the genital tract may become promising candidates for prophylactic vaccine against HIV-1 infection. We have previously reported that concanavalin A-immobilized polystyrene nanospheres (Con A-NS) could efficiently capture HIV-1 particles and gp120 antigens on their surface and that intravaginal immunization with inactivated HIV-1-capturing nanospheres (HIV-NS) induced vaginal anti-HIV-1 IgA antibody in mice. In this study, various strategies for immunization with HIV-NS were undertaken to induce HIV-1-specific IgA response in the mouse genital tract. HIV-NS were administered intravaginally, orally, intranasally or intraperitoneally to mice. Progesterone treatment enhanced the anti-HIV-1 IgA response to intravaginal immunization significantly, but intranasal immunization with HIV-NS was more effective compared with other immunization routes in terms of vaginal IgA response. In addition, vaginal washes from intranasally immunized mice were capable of neutralizing HIV-1(IIIB). Thus, application of HIV-NS is a practical approach to promote HIV-1-specific IgA response by the vaginal mucosa in the mouse and intranasal appears to be an effective immunization route in this animal model. Intranasal immunization with HIV-NS should be further pursued for its potential as an HIV-1 prophylactic vaccine.

Gene expression and mucosal immune responses after vaginal DNA immunization in mice using a controlled delivery matrix

IgA antibodies in the vaginal tract are essential as a first defense line against microorganisms that enter the body via mucosal surfaces. Several studies have shown that direct application of DNA to the vaginal mucosal surface can induce secretion of IgA molecules specific to the expressed protein. The major challenge of formulating effective vaccines is to overcome the barriers to DNA administration caused by the estrus cycle and physical environment of the vaginal tract. In this study, we investigated whether controlled delivery of DNA to the vaginal surface would induce long-term IgA antibody production by applying controlled delivery matrices to the vaginal tract. The controlled DNA delivery matrices were composed of poly(ethylene-co-vinyl acetate) (EVAc) and loaded with a model plasmid encoding sperm-specific lactate dehydrogenase C(4) (LDH-C(4)). These EVAc matrices provided a controlled and sustained DNA release to the vaginal mucosal surface. The DNA released from the EVAc disks was functionally active and capable of transfecting vaginal tissues. When inserted into the vaginal tract of mice, the DNA-loaded EVAc matrices triggered the immune system and induced specific IgA to LDH-C(4) in the vaginal secretions. These results demonstrate that the EVAc disks are efficient and convenient vehicles for delivering DNA to the vaginal tract and providing long-term local immunity.

Female sex hormones as regulatory factors in the vaginal immune compartment

Sexually transmitted diseases (STD) are now considered to be among the most common human infections. The incidence of STD is on the rise, which is partly due to frequent transmission during the asymptomatic phase of infection. The compounded cost of STD just in the United States is estimated to exceed $10 billion annually. STD are particularly prevalent in teenagers and young adults and the health problems caused by these diseases tend to be more severe and more frequent in woman than in men. Despite considerable efforts, a vaccine that provides protective immunity against sexually transmitted diseases in humans has not been developed. Nonetheless, research in animal models indicates that strong local and regional immune responses can influence the outcome of vaginal challenge with microbial pathogens. Vaginal immunity is an area of basic immunology that has received relatively little attention, but it is already clear that the mucosal and regional immunology of the vagina has unique features. The present review summarizes some of the anatomical, physiological and immunological features of the vagina and uterus that distinguish humans, non-human primates, rats and mice. These interspecies differences need to be taken into account in laboratory efforts to develop effective vaccines for STD in humans.

Slight influence of the estrous cycle stage on the mucosal and systemic specific antibody response induced after vaginal and intraperitoneal immunization with protoxin Cry1Ac from Bacillus thuringiensis in mice

Since the immune response appears to be variable according to the hormonal stage of the mammalian female, the aim of this study was to determine whether estrous cycle stage modifies the mucosal and systemic immune responses induced by intraperitoneal and vaginal immunization of mice with protoxin Cry1Ac. We tested the influence of three immunizations on the specific antibody response elicited at estrus and diestrus, that were the same estrous cycle stages at which the antigen was applied. Both intraperitoneal and vaginal immunization of mice with Cry1Ac either at estrus or diestrus induces specific antibody responses at serum, vagina and large intestine. The stage of the estrous cycle have little or non influence in the magnitude of the response induced, since only at serum the IgM was slightly higher at estrus than at diestrus by both routes. At the large intestine only the IgA response elicited via the intraperitoneal route changed, being higher at diestrus, whereas at the vagina IgA response induced did not change significantly due to the cycle stage. Present results suggest that Cry1Ac may be used as an antigen carrier as it can elicit antibody responses at systemic level and at several mucosal sites including the vagina that are not modified significantly throughout the reproductive cycle.

Differential induction of mucosal and systemic antibody responses in women after nasal, rectal, or vaginal immunization: influence of the menstrual cycle

A cholera vaccine containing killed vibrios and cholera toxin B subunit (CTB) was used to compare mucosal immunization routes for induction of systemic and mucosal Ab. Four groups of women were given three monthly immunizations by the rectal immunization (R(imm)) route, nasal immunization (N(imm)) route, or vaginal immunization route during either the follicular (V-FP(imm)) or luteal (V-LP(imm)) menstrual cycle phase. N(imm) was performed with 10-fold less vaccine to determine if administration of less Ag by this route can, as in rodents, produce mucosal Ab responses comparable to those induced by higher dose R(imm) or vaginal immunization. Concentrations of Ab induced in sera and secretions were measured by ELISA. None of these routes produced durable salivary Ab responses. N(imm) induced greatest levels of CTB-specific IgG in sera. R(imm) failed to generate CTB-specific IgA in genital tract secretions. N(imm), V-FP(imm), and V-LP(imm) all produced cervical CTB-specific IgA responses comparable in magnitude and frequency. However, only V-FP(imm) induced cervical IgA2-restricted Ab to the bacterial LPS vaccine component. V-FP(imm), but not V-LP(imm), also induced CTB-specific IgA in rectal secretions. N(imm) was superior to V-FP(imm) for producing rectal CTB-specific IgA, but the greatest amounts of CTB-specific IgA and LPS-specific IgA, IgG, and IgM Ab were found in rectal secretions of R(imm) women. These data suggest that in women, N(imm) alone could induce specific Ab in serum, the genital tract, and rectum. However, induction of genital tract and rectal Ab responses of the magnitude generated by local V-FP(imm) or R(imm) will likely require administration of comparably high nasal vaccine dosages.

Fc receptor regulation of protective immunity against Chlamydia trachomatis

The prevailing paradigm for designing potentially efficacious vaccines against the obligate intracellular bacterium, Chlamydia trachomatis, advocates regimens capable of inducing a mucosal antigen-specific T helper type 1 (Th1) response. However, recent reports indicate that rapid and efficient clearance of a secondary infection also requires certain B-cell functions. We investigated the hypothesis that Fc receptor (FcR)-mediated antibody effector mechanisms are important B-cell-related functions involved in controlling a chlamydial genital reinfection. Microbiological analysis of genital chlamydial infection in FcR knockout (FcRKO) mice lacking the activatory FcgammaRI (CD64) and FcRgammaIII (CD16), as well as the inhibitory FcgammaRIIB1 (CD32), revealed a greater intensity of secondary infection (i.e. bacterial shedding) in FcRminus sign/minus sign as compared to FcR+/+ mice; however, the course of the primary infection was indistinguishable in both animals. Pathologically, FcRKO mice suffered greater ascending infection than immunocompetent wild-type (WT) mice after a secondary infection. Immunological evaluation indicated that the presence of specific anti-chlamydial antibodies enhanced chlamydial antigen presentation for induction of a Th1 response by FcR+/+, but not FcRminus sign/minus sign, antigen-presenting cells. In addition, specific anti-chlamydial antibodies augmented both macrophage killing of infected epithelial cells by antibody-dependent cellular cytotoxicity (ADCC) and macrophage inhibition of productive growth of chlamydiae in co-cultures. These results indicate that B cells participate in anti-chlamydial immunity via FcR-mediated effector functions of antibodies, which are operative during reinfections. Such effector functions include ADCC, and possibly enhanced uptake, processing and presentation of chlamydial antigens for rapid induction of a Th1 response, all facilitating the early clearance of an infection. These findings suggest that a future anti-chlamydial vaccine should elicit both humoral and T-cell-mediated immune responses for optimal memory response and vaccine efficacy.

Nasal and vaginal vaccinations have differential effects on antibody responses in vaginal and cervical secretions in humans

Sexually transmitted diseases are a major health problem worldwide, but there is still a lack of knowledge about how to induce an optimal immune response in the genital tract of humans. In this study we vaccinated 21 volunteers nasally or vaginally with the model mucosal antigen cholera toxin B subunit and determined the level of specific immunoglobulin A (IgA) and IgG antibodies in vaginal and cervical secretions as well as in serum. To assess the hormonal influence on the induction of antibody responses after vaginal vaccination, we administered the vaccine either independently of the stage in the menstrual cycle or on days 10 and 24 in the cycle in different groups of subjects. Vaginal and nasal vaccinations both resulted in significant IgA and IgG anti-cholera toxin B subunit responses in serum in the majority of the volunteers in the various vaccination groups. Only vaginal vaccination given on days 10 and 24 in the cycle induced strong specific antibody responses in the cervix with 58-fold IgA and 16-fold IgG increases. In contrast, modest responses were seen after nasal vaccination and in the other vaginally vaccinated group. Nasal vaccination was superior in inducing a specific IgA response in vaginal secretions, giving a 35-fold increase, while vaginal vaccination induced only a 5-fold IgA increase. We conclude that a combination of nasal and vaginal vaccination might be the best vaccination strategy for inducing protective antibody responses in both cervical and vaginal secretions, provided that the vaginal vaccination is given on optimal time points in the cycle.

Evaluation of the cervical cytobrush sampling technique for the preparation of CD45+ mononuclear cells from the human cervix

A cytobrush technique developed to prepare mononuclear cells from the intraepithelial layer of the endocervix has been evaluated. Specimens yielded approximately 4-6x10(6) cells, of which 10-15% were CD45+. Between 10% and 15% of these CD45+ cells were mononuclear leukocytes. The non-leukocyte cell fraction exhibited high levels of autofluorescence and for flow cytometry analysis, it was necessary to exclude these cells by gating. Macrophages constituted approximately 60% and T lymphocytes, 40% of the mononuclear cells in cytobrush samples. The CD4/CD8 T-cell ratio was similar to that observed in blood. In 9 of 13 specimens, B lymphocytes constituted less than 1% of the mononuclear cell fraction suggesting that the mononuclear cells were derived from the intraepithelial compartment rather then the deeper lamina propria. Lack of B lymphocytes also indicates minimal blood contamination in these samples, a conclusion supported by labelling for the red blood cell (RBC) glycoprotein glycophorin A. However, the need to monitor all samples for possible blood contamination was indicated by 4 of 13 samples in which B lymphocytes accounted for 2-8% of the mononuclear cells.

Macrophages are increased in cervical epithelium of women with cervicitis

BACKGROUND

Sexually transmitted diseases (STIs) are major causes of morbidity in women. The mechanisms involved in establishment of genital mucosal infection are poorly defined.

OBJECTIVE

To investigate changes in cervical epithelial (CE) CD45+ cell subpopulations in women with microscopic evidence of cervicitis (n=9) and those without (n=12).

METHODS

CE samples were obtained using cytobrush including matched venous blood. CE and peripheral blood (PB) mononuclear cells were analysed by flow cytometry for CD3+, CD4+, CD8+, CD14+,CD19+, and HLA-DR+ expression.

RESULTS

Women with cervicitis had increased CE macrophages compared with those without (p<0.05). MHC class II+ cells were predominant in all cervical samples. Considerably fewer B lymphocytes were found in cervical samples in both groups of women. No changes were observed in cervical T lymphocyte subsets. However, a relative CD8+ lymphocytosis in PB was noted in women with cervicitis.

CONCLUSION

The increased numbers of CE macrophages in women with cervicitis may have important implications for pathogenesis of STIs including human immunodeficiency virus infection.

Preparation and preclinical evaluation of experimental group B streptococcus type III polysaccharide-cholera toxin B subunit conjugate vaccine for intranasal immunization

Streptococcus group B (GBS) is usually carried asymptomatically in the vaginal tract of women and can be transferred to the newborn during parturition. Serum antibodies to the capsular polysaccharide (CPS) can prevent invasive diseases, whereas immunity acting at the mucosal surface may be more important to inhibit the mucosal colonization of GBS and thus the risk of infection for the newborn. We prepared different GBS type III CPS-protein conjugate vaccines and evaluated their systemic and mucosal immunogenicity in mice. GBS type III CPS was conjugated to tetanus toxoid (TT) or recombinant cholera toxin B subunit (rCTB) either directly or to rCTB indirectly via TT. The conjugation was performed by different methods: (1) CPS was coupled to TT with 1-ethyl-3 (3-dimethylaminopropyl)-carbodiimide (EDAC), using adipic acid dihydrazide (ADH) as a spacer; (2) CPS was conjugated with rCTB using reductive amination; or, (3) N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP) was used to bind rCTB to the TT of the CPS-TT conjugate. Mice were immunized with these conjugates or purified CPS by subcutaneous (s.c.) and intranasal (i. n.) routes. Antibodies to GBS III in serum, lungs and vagina were measured with ELISA. All of the CPS-protein conjugates were superior to unconjugated CPS in eliciting CPS-specific immune responses in serum and mucosal tissue extracts. The conjugates, when administrated s.c., induced only IgG responses in serum, lung and vagina, while i.n. vaccination also elicited IgA responses in the lungs and vagina. The CPS-TT conjugate administrated i.n. induced a strong serum IgG, but only a weak mucosal IgA response, while the CPS-rCTB conjugate elicited high IgG as well as IgA antibodies in the lungs after i.n. immunization. GBS III CPS-TT conjugated with rCTB produced a strong systemic and local anti-CPSIII response after i.n. administration. Co-administration of CT as adjuvant enhanced the anti-CPS systemic and mucosal immune responses further after i.n. administration with the CPS conjugates. These findings indicate that: (i) i.n. immunization with GBS CPS-protein conjugates was more effective than s.c immunization for stimulating serum as well as mucosal immune responses; (ii) rCTB as a carrier protein for GBS III CPS could markedly improve the mucosal immune response; and (iii) the experimental GBS type III CPS conjugates containing rCTB should be investigated as mucosal vaccine to prevent GBS infection in humans.

Expression of mucosal homing receptor alpha4beta7 is associated with enhanced migration to the Chlamydia-infected murine genital mucosa in vivo

The CD4 T helper cell type 1 (Th1) response is essential for the resolution of chlamydial genital infection in mice. However, not all Th1 clones are equally protective in eradicating the infection. Since oral immunization regimens produce protective immunity, we evaluated the role of the mucosa-associated homing receptor, alpha4beta7, in trafficking to the genital mucosa. Using a panel of CD4, Th1 cell lines and clones, we compared the lymphocyte homing patterns of a Chlamydia-specific, protective clone (P-MoPn), a nonprotective clone (N-MoPn), and a keyhole limpet hemocyanin (KLH)-specific cell line (KLH-1). T cells were labeled with the fluorescent dye PKH-26, adoptively transferred into Chlamydia-infected mice, and monitored at different time points throughout the course of a genital infection. We found that clones P-MoPn and N-MoPn migrated to similar extents to the genital tract and in significantly greater numbers than the KLH-specific T-cell line. Both clones and the KLH-1 line expressed similar levels of the adhesion molecules alpha4, beta1, CD44, and CD11a. However, clones P-MoPn and N-MoPn expressed higher levels of the mucosal homing receptor, alpha4beta7. Also, clones P-MoPn and N-MoPn but not the KLH-1 line migrated to the mesenteric lymph node, suggesting a mucosal recirculation pattern. Moreover, blocking alpha4beta7 adhesion interaction in vivo significantly reduced the recruitment of P-MoPn but not KLH-1 to the genital tract. These findings show that the mucosal homing receptor alpha4beta7 is utilized by a subset of CD4 cells during migration to the Chlamydia-infected genital tract.

Simian immunodeficiency virus rapidly penetrates the cervicovaginal mucosa after intravaginal inoculation and infects intraepithelial dendritic cells

Despite recent insights into mucosal human immunodeficiency virus (HIV) transmission, the route used by primate lentiviruses to traverse the stratified squamous epithelium of mucosal surfaces remains undefined. To determine if dendritic cells (DC) are used by primate lentiviruses to traverse the epithelial barrier of the genital tract, rhesus macaques were intravaginally exposed to cell-free simian immunodeficiency virus SIVmac251. We examined formalin-fixed tissues and HLA-DR(+)-enriched cell suspensions to identify the cells containing SIV RNA in the genital tract and draining lymph nodes within the first 24 h of infection. Using SIV-specific fluorescent in situ hybridization combined with immunofluorescent antibody labeling of lineage-specific cell markers, numerous SIV RNA(+) DC were documented in cell suspensions from the vaginal epithelium 18 h after vaginal inoculation. In addition, we determined the minimum time that the SIV inoculum must remain in contact with the genital mucosa for the virus to move from the vaginal lumen into the mucosa. We now show that SIV enters the vaginal mucosa within 60 min of intravaginal exposure, infecting primarily intraepithelial DC and that SIV-infected cells are located in draining lymph nodes within 18 h of intravaginal SIV exposure. The speed with which primate lentiviruses penetrate mucosal surfaces, infect DC, and disseminate to draining lymph nodes poses a serious challenge to HIV vaccine development.

Antibody responses to a mucosally delivered HIV-1 gp120-derived C4/V3 peptide

T1-SP10MN(A) is a synthetic peptide containing a T-helper (Th), cytotoxic T cell (CTL) and a B-cell epitope derived from the HIV-1 gp120 envelope protein. This peptide can elicit both systemic and mucosal antibody responses following nasal immunization in various species. In the present study, three different mucosal immunization strategies were performed in rabbits to determine which induced a more vigorous antibody response to T1-SP10MN(A). Nasal immunization followed by nasal boosting was found to be superior at inducing both serum IgG and vaginal secretory IgA (S-IgA) when compared to nasal followed by vaginal boosting. Conversely, vaginal priming followed by vaginal boosting elicited minimal serum IgG and vaginal S-IgA responses to T1-SP10MN(A), but moderate levels of vaginal IgG were detected. This study further demonstrates that vaginal immune responses can be elicited by immunization at distant and local mucosal sites.

Analysis of vaginal cell populations during experimental vaginal candidiasis

Studies with an estrogen-dependent murine model of vaginal candidiasis suggest that local cell-mediated immunity (CMI) is more important than systemic CMI for protection against vaginitis. The present study, however, showed that, compared to uninfected mice, little to no change in the percentage or types of vaginal T cells occurred during a primary vaginal infection or during a secondary vaginal infection where partial protection was observed. Furthermore, depletion of polymorphonuclear leukocytes (PMN) had no effect on infection in the presence or absence of pseudoestrus. These results indicate a lack of demonstrable effects by systemic CMI or PMN against vaginitis and suggest that if local T cells are important, they are functioning without showing significant increases in numbers within the vaginal mucosa during infection.

The potential use of sperm antigens as targets for immunocontraception; past, present and future

Immunocontraception, and in particular the targeting of antibodies to gamete-specific antigens implicated in sperm egg binding and fertilisation, offers an attractive approach to the growing global problem of overpopulation. Such an idea is not new; indeed several immunocontraception trials, using animal model systems, have been reported in recent years and a number are reviewed here. However, the results of these studies have been largely disappointing. We believe that two fundamental flaws attribute to the poor success of most of these preliminary immunocontraceptive trials. Firstly, loss of fertility has invariably been used as the assay. This presupposes that immuno-neutralisation of a single, gamete-specific antigen will be sufficient to cause a significant reduction in fertility; however, recent data suggests that such a premise may not be well-founded for a number of reasons. Secondly, and arguably the most important flaw, is the almost universal, but largely inappropriate, use of systemic immunisation as the sole route of antigen delivery. Whilst systemic immunisation regimes may lead to high serum IgG levels, these levels do not correlate with specific antibody levels in the reproductive tract or with contraceptive efficacy. Hence, an alternative antigen delivery approach is required which will induce an effective local immune response in the reproductive tract. Here we discuss the ways in which this might be achieved.

Immunity to Chlamydia trachomatis mouse pneumonitis induced by vaccination with live organisms correlates with early granulocyte-macrophage colony-stimulating factor and interleukin-12 production and with dendritic cell-like maturation

As is true for other intracellular pathogens, immunization with live Chlamydia trachomatis generally induces stronger protective immunity than does immunization with inactivated organism. To investigate the basis for such a difference, we studied immune responses in BALB/c mice immunized with viable or UV-killed C. trachomatis mouse pneumonitis (MoPn). Strong, acquired resistance to C. trachomatis infection was elicited by immunization with viable but not dead organisms. Immunization with viable organisms induced high levels of antigen-specific delayed-type hypersensitivity (DTH), gamma interferon production, and immunoglobulin A (IgA) responses. Immunization with inactivated MoPn mainly induced interleukin-10 (IL-10) production and IgG1 antibody without IgA or DTH responses. Analysis of local early cytokine and cellular events at days 3, 5, and 7 after peritoneal cavity immunization showed that high levels of granulocyte-macrophage colony-stimulating factor and IL-12 were detected with viable but not inactivated organisms. Furthermore, enrichment of a dendritic cell (DC)-like population was detected in the peritoneal cavity only among mice immunized with viable organisms. The results suggest that early differences in inducing proinflammatory cytokines and activation and differentiation of DCs may be the key mechanism underlying the difference between viable and inactivated organisms in inducing active immunity to C. trachomatis infection.

Intranasal Immunization with Plasmid DNA-Lipid Complexes Elicits Mucosal Immunity in the Female Genital and Rectal Tracts

The development of vaccines against pathogens transmitted across the genito-rectal mucosa that effectively stimulate both secretory IgA Abs and cytotoxic T lymphocytes in the genital tract and CTL in the draining lymph nodes (LN) has proven a major challenge. Here we report a novel, noninvasive approach of genetic vaccination via the intranasal route. Such vaccination elicits immune responses in the genital and rectal mucosa, draining LNs, and central lymphoid system. Intranasal immunization with plasmid DNA-lipid complexes encoding the model Ag firefly luciferase resulted in dissemination of the DNA and the encoded transcript throughout the respiratory and gastrointestinal tracts, draining LNs, and spleen. Complexing the plasmid DNA with the lipid DMRIE/DOPE enhanced expression of the encoded protein in the respiratory tract, increased specific secretory IgA Ab in the vaginal and rectal tracts, and increased the circulating levels of specific IgA and IgG. In addition, intranasal DNA immunization resulted in generation of Ag-specific CTL that were localized in the genital and cervical LNs and spleen. These results suggest that intranasal immunization with plasmid DNA-lipid complexes may represent a generic immunization strategy against pathogens transmitted across the genito-rectal and other mucosal surfaces.

Dendritic cells route human immunodeficiency virus to lymph nodes after vaginal or intravenous administration to mice

We have developed a murine model to study the involvement of dendritic cells (DC) in human immunodeficiency virus (HIV) routing from an inoculation site to the lymph nodes (LN). Murine bone marrow-derived DC migrate to the draining LN within 24 h after subcutaneous injection. After incubation of these cells with heat-inactivated (Hi) HIV type 1 (HIV-1), HIV RNA sequences were detected in the draining LN only. Upon injection of DC pulsed with infectious HIV, the virus recovered in the draining LN was still able to productively infect human T cells. After a vaginal challenge with Hi HIV-1, the virus could be detected in the iliac and sacral draining LN at 24 h after injection. After an intravenous challenge, the virus could be detected in peripheral LN as soon as 30 min after injection. The specific depletion of a myeloid-related LN DC population, previously shown to take up blood macromolecules and to translocate them into the LN, prevented HIV transport to LN. Together, our data demonstrate the critical role of DC for HIV routing to LN after either a vaginal or an intravenous challenge, which does not require their infection. Therefore, despite the fact that the mouse is not infectable by HIV, this small animal model might be useful to test preventive strategies against HIV.

Protection against ascending infection of the genital tract by Chlamydia trachomatis is associated with recruitment of major histocompatibility complex class II antigen-presenting cells into uterine tissue

A mouse model of ascending infection following intravaginal inoculation with a strain of Chlamydia trachomatis isolated from humans has been used to identify immune mechanisms associated with protection against genital infection. BALB/c and C3H mice differed in their susceptibilities to infection and inflammatory disease. In both mouse strains, ascension of the organism and recruitment of bone marrow-derived mononuclear leukocytes were evident in uterine tissue 1 week postinfection. By 3 weeks the organism had been cleared and inflammation had been resolved in the BALB/c mice, but both persisted in the C3H animals. In athymic nude BALB/c mice both the organism and inflammation persisted, indicating the influence of the hosts' immune response on the outcome of infection. Both BALB/c and C3H mice had a Th1 response in draining lymph nodes, with predominant production of gamma interferon and tumor necrosis factor alpha, low levels of interleukin-10, and no detectable levels of interleukin-4. However, the composition of the early uterine infiltrate differed in these two mouse strains. Cell surface labeling and analysis of light scatter properties by flow cytometry identified a population of large, CD45(+) major histocompatibility complex class II mononuclear cells, which were a prominent feature of the infiltrates in BALB/c mice but were present in significantly lower numbers in C3H mice. These cells expressed the costimulatory molecules CD86 and CD40 and stimulated allogeneic T cells, suggesting that these mononuclear cells are a population of antigen-presenting cells and that they may play a role in clearing antigen and protecting against inflammatory disease in BALB/c mice. An additional level of immunological control may thus exist in genital chlamydial infection.

Immunity to vaginal infection by herpes simplex virus type 2 in adult mice: characterization of the immunoglobulins in vaginal mucus

Progestin-treated female mice are susceptible to vaginal infection by two sexually transmitted disease organisms: herpes simplex virus type 2 (HSV-2) and Chlamydia trachomatis. Vaccination of mice with HSV-2 or chlamydial antigens elicits immunity to vaginal infection that may be due in part to secreted antibodies in the vaginal lumen. Analysis of the role of these antibodies in immunity would be aided by information about the vaginal secretion in progestin-treated mice and the antibodies it contains. Gross and histologic observations of progestin-treated mice that were immune to vaginal HSV-2 infection indicated that the vaginal lumen was filled with mucus. A procedure for extraction of immunoglobulin from the mucus was developed and shown to recover at least 98% of the secretory IgA (S-IgA) that was free to diffuse from the mucus. Immunoblotting revealed that the predominant molecular form of IgA in vaginal mucus was dimeric S-IgA. Immunoglobulin concentrations in vaginal secretions were higher in immune mice than in non-immune mice and S-IgA concentrations were higher than those of IgG. The IgG concentration in vaginal secretions of immune mice was 4.5-fold higher than in non-immune mice, while serum IgG increased only 1.5-fold, suggesting local production of IgG or increased transudation in immune mice. Specific IgG antibody to HSV-2 was demonstrated in vaginal secretions of immune mice at a mean ELISA titer of 6200, whereas the titer of specific S-IgA in the same secretions was only 1.9. Thus, while the predominant immunoglobulin by weight in the vaginal mucus of immune mice was S-IgA, the ELISA titers suggested that the virus-specific antibody was almost entirely IgG.

Vaginal immunization with recombinant gram-positive bacteria

PROBLEM

Many viral and bacterial pathogens enter the body through the genital mucosa. Therefore, one of the major goals of a vaccine against sexually transmitted diseases (STDs) should be to induce an immune response in the genital mucosa capable of controlling the entry of the pathogen. Our approach for the development of vaccines against STDs is based on the use of nonpathogenic Gram-positive bacteria as live vaccine vectors.

METHOD OF STUDY

Recombinant Gram-positive bacteria expressing vaccine antigens were constructed using genetic systems developed in our laboratory. Balb/c mice and Cynomolgus monkeys were inoculated by the vaginal route and vaginal samples were collected using absorbent wicks. Colonization was evaluated by the presence of recombinant bacteria in the vaginal samples. Local and systemic immune responses were studied.

RESULTS

We have developed genetic systems for the expression of heterologous antigens on the surface of the human commensals Streptococcus gordonii and Lactobacillus spp. Both S. gordonii and L. casei stably colonized the murine vagina after a single inoculum. Vaginal colonization of mice with recombinant strains of S. gordonii, expressing human papillomavirus (HPV) and human immunodeficiency virus (HIV) antigens, induced antigen-specific vaginal immunoglobulin A (IgA) and serum IgG. Local and systemic immune responses also were detected in monkeys immunized intravaginally with recombinant S. gordonii.

CONCLUSION

The results obtained indicated that the approach of using colonizing Gram-positive bacteria as live vectors has a great potential for the development of vaccines against STDs.

Internalization of Chlamydia by Dendritic Cells and Stimulation of Chlamydia-Specific T Cells

Chlamydia species are the causative agents of trachoma, various forms of pneumonia, and the most common sexually transmitted diseases. Although the infection cycle has been extensively characterized in epithelial cells, where the Chlamydia entry-vacuoles avoid fusion with host-cell lysosomes, the cellular immune response has received less attention. Moreover, despite the abundant presence of dendritic cells (DC) in the sites of infection, the interaction between Chlamydia and DC has never been studied. We observe that DC kill Chlamydia trachomatis and Chlamydia psittaci. The chlamydiae are internalized by the DC in a nonspecific manner through macropinocytosis, and the macropinosomes fuse subsequently with DC lysosomes expressing MHC class II molecules. The interaction induces maturation of the DC, since presentation of an exogenous Ag is severely inhibited after a 1-day incubation, although chlamydial Ags are still presented and recognized by Chlamydia-specific CD4+ T cells. Thus, DC most likely play a role in initiating the T cell response in vivo and could potentially be used in adoptive transfer therapies to vaccinate against Chlamydia.

Antibodies and antibody-secreting cells in the female genital tract after vaginal or intranasal immunization with cholera toxin B subunit or conjugates

We studied the antibody response including antibody-secreting cells (ASC) in the female genital tract of mice after mucosal immunizations with the recombinant B subunit of cholera toxin (rCTB) perorally, intraperitoneally, vaginally, and intranasally (i.n.). The strongest genital antibody responses as measured with a novel perfusion-extraction method were induced after vaginal and i.n. immunizations, and these routes also gave rise to specific immunoglobulin A (IgA) and IgG ASC in the genital mucosa. Specific ASC in the iliac lymph nodes, which drain the female genital tract, were seen only after vaginal immunization. Progesterone treatment increased the ASC response in the genital tissue after all mucosal immunizations but most markedly after vaginal immunization. We also tested rCTB as a carrier for human gamma globulin (HGG) and the effect of adding cholera toxin (CT) as an adjuvant for the induction of systemic and genital antibody responses to HGG after vaginal and i.n. immunizations. Vaginal immunizations with HGG conjugated to rCTB resulted in high levels of genital anti-HGG antibodies whether or not CT was added, while after i.n. immunization the strongest antibody response was seen with the conjugate together with CT. In summary, vaginal and i.n. immunization give rise to a specific mucosal immune response including ASC in the genital tissue, and vaginal immunization also elicits ASC in the iliac lymph nodes. We have also shown that rCTB can act as an efficient carrier for a conjugated antigen for induction of a specific antibody response in the genital tract of mice after vaginal or i.n. immunization.

Immunization of the female genital tract with a DNA-based vaccine

Vaccines are being sought for contraception and the prevention of sexually transmitted diseases. However, progress is slow in this area largely because of lack of information on induction of protective immune responses in genital tract mucosa. In this study, we investigated whether in vivo transfection with a model DNA-based antigen delivered by gene gun technology would induce an antibody response detectable in vaginal secretions. Female rats were immunized with plasmids encoding human growth hormone (HGH) under the control of a cytomegalovirus promoter (pCMV/HGH) via vaginal mucosa (V), Peyer's patch (PP), and/or abdominal skin (S) routes. Localization of HGH in the target tissues demonstrated that all three sites can be transfected in vivo with pCMV/HGH. Vaginal tissues expressed roughly the same level of plasmid as skin. Antibodies to HGH were detectable in serum and vaginal secretions in rats immunized with pCMV/HGH. In the rats primed and boosted vaginally, vaginal immunoglobulin A (IgA) and IgG antibody titers to HGH were sustained for at least 14 weeks, whereas rats immunized via other routes and protocols (S/V, S/S, PP/PP, or PP/V) did not consistently sustain significant vaginal antibody titers beyond week 6. DNA-based immunizations administered by the gene gun may be an effective method of inducing local immunity in the female genital tract.

Protective immunity against HSV-2 in the mouse vagina

Herpes simplex virus type 2 (HSV-2) is a sexually transmitted pathogen that infects the genital tract. The high prevalence of HSV-2 in humans underscores the need to develop an effective vaccine. Efforts to develop vaccines to protect women against this and other sexually transmitted pathogens would be facilitated by a better understanding of the immune mechanisms that protect the female reproductive tract against infections in animal models. Such information would be invaluable in developing vaccine strategies to promote the type and magnitude of immune responses in the genital tract that would effectively protect against infection. This review focuses on recent studies using a progestin-treated adult mouse model to explore mucosal immunity to HSV-2 in the vagina. Evidence indicating a major role for both humoral and T cell immunity is presented.

Immunopathogenesis of recurrent vulvovaginal candidiasis

Recurrent vulvovaginal candidiasis (RVVC) is a prevalent opportunistic mucosal infection, caused predominantly by Candida albicans, which affects a significant number of otherwise healthy women of childbearing age. Since there are no known exogenous predisposing factors to explain the incidence of symptomatic vaginitis in most women with idiopathic RVVC, it has been postulated that these particular women suffer from an immunological abnormality that prediposes them to RVVC. Because of the increased incidence of mucosal candidiasis in individuals with depressed cell-mediated immunity (CMI), defects in CMI are viewed as a possible explanation for RVVC. In this review, we attempt to place into perspective the accumulated information regarding the immunopathogenesis of RVVC, as well as to provide new immunological perspectives and hypotheses regarding potential immunological deficiencies that may predispose to RVVC and potentially other mucosal infections by the same organism. The results of both clinical studies and studies in an animal model of experimental vaginitis suggest that systemic CMI may not be the predominant host defense mechanism against C. albicans vaginal infections. Rather, locally acquired mucosal immunity, distinct from that in the peripheral circulation, is now under consideration as an important host defense at the vaginal mucosa, as well as the notion that changes in local CMI mechanism(s) may predispose to RVVC.

Antigen sampling across epithelial barriers and induction of mucosal immune responses

Epithelial barriers on mucosal surfaces at different sites in the body differ dramatically in their cellular organization, and antigen sampling strategies at diverse mucosal sites are adapted accordingly. In stratified and pseudostratified epithelia, dendritic cells migrate to the outer limit of the epithelium, where they sample antigens for subsequent presentation in local or distant organized lymphoid tissues. In simple epithelia, specialized epithelial M cells (a phenotype that occurs only in the epithelium over organized lymphoid follicles) deliver samples of foreign material by transepithelial transport from the lumen to organized lymphoid tissues within the mucosa. Certain pathogens exploit the M cell transport process to cross the epithelial barrier and invade the mucosa. Here we review the features of M cells that determine antigen and pathogen adherence and transport into mucosal lymphoid tissues.

Induction of antigen-specific antibodies in vaginal secretions by using a nontoxic mutant of heat-labile enterotoxin as a mucosal adjuvant

Immunization of the female reproductive tract is important for protection against sexually transmitted diseases and other pathogens of the reproductive tract. However, intravaginal immunization with soluble antigens generally does not induce high levels of secretory immunoglobulin A (IgA). We recently developed safe mucosal adjuvants by genetically detoxifying Escherichia coli heat-labile enterotoxin, a molecule with a strong mucosal adjuvant activity, and here we describe the use of the nontoxic mutant LTK63 to induce a response in the mouse vagina against ovalbumin (Ova). We compared intravaginal and intranasal routes of immunization for induction of systemic and vaginal responses against LTK63 and Ova. We found that LTK63 is a potent mucosal immunogen when given by either the intravaginal or intranasal route. It induces a strong systemic antibody response and IgG and long-lasting IgA in the vagina. The appearance of vaginal IgA is delayed in the intranasally immunized mice, but the levels of vaginal anti-LTK63 IgA after repeated immunizations are higher in the intranasally immunized mice than in the intravaginally immunized mice. LTK63 also acts as a mucosal adjuvant, inducing a serum response against Ova, when given by both the intravaginal and intranasal routes. However, vaginal IgA against Ova is stimulated more efficiently when LTK63 and antigen are given intranasally. In conclusion, our results demonstrate that LTK63 can be used as a mucosal adjuvant to induce antigen-specific antibodies in vaginal secretions and show that the intranasal route of immunization is the most effective for this purpose.

A recombinant Salmonella typhimurium vaccine induces local immunity by four different routes of immunization

Immunization of mice with an attenuated Salmonella typhimurium strain (Phopc) carrying a plasmid encoding a hybrid form of the hepatitis B virus core antigen (HBc) induced specific antibody responses against the bacterial lipopolysaccharide (LPS) and HBc. Different mucosal routes of immunization, i.e., oral, nasal, rectal, and vaginal, were compared for their ability to induce a systemic as well as a mucosal response at sites proximal or distant to the site of immunization. Anti-LPS and anti-HBc immunoglobulin A (IgA) antibodies were measured in saliva, in feces, and in genital, bronchial, and intestinal secretions. Specific antibodies in serum and secretions were observed after immunization via all routes; however, the response to LPS was independent of that against HBc. In serum, saliva, and genital and bronchial secretions, high amounts of anti-HBc IgA were obtained by the nasal route of immunization. Vaginal immunization resulted in two different responses in mice: high and low. We observed a correlation between the level of specific immune response and the estrous status of these mice at the time of immunization. Rectal immunization induced high amounts of IgA against HBc and LPS in colonorectal secretions and feces but not at distant sites. These data suggest that S. typhimurium is able to invade different mucosal tissues and induce long-lasting local IgA responses against itself and a carried antigen after a single immunization.

Local Th1-like responses are induced by intravaginal infection of mice with the mouse pneumonitis biovar of Chlamydia trachomatis

A critical role for cell-mediated immunity (CMI) has been demonstrated for effecting the resolution of genital infections of mice infected intravaginally with the mouse pneumonitis biovar of Chlamydia trachomatis (MoPn). However, little is known about expression of CMI in the murine genital tract. The mouse MoPn model was used to examine CMI responses in the genital tract and associated lymph nodes during the course of infection. MoPn-specific lymphocytes were present in the genital mucosa, with the maximum level of proliferation in response to MoPn at 3 weeks postinfection. MoPn-stimulated cells secreting gamma interferon were also detected in the cells from the genital mucosa, but few interleukin-4-secreting cells were seen at any time postinfection, indicating the induction of a Th1-like response in the cells of the genital mucosa. The iliac node draining the genital tract was the major node stimulated as a result of a genital infection and exhibited a predominant Th1-like pattern of cytokine secretion as well. Mesenteric lymph node cells demonstrated poor proliferative responses to MoPn and few antigen-stimulated cytokine-secreting cells after the primary infection. However, 7 days after a second infection administered 50 days following the primary infection, there was a marked increase in both proliferative responses and the frequencies of MoPn-stimulated gamma interferon- and interleukin-4-secreting cells. These studies provided information regarding the local CMI response to MoPn in mice which may prove valuable in the development of vaccination strategies for the prevention of chlamydial genital infections.