T lymphocytes in the murine vaginal mucosa are phenotypically distinct from those in the periphery

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.

High-Throughput Humanized Mouse Models for Evaluation of HIV-1 Therapeutics and Pathogenesis

Mice cannot be used as a model to evaluate HIV-1 therapeutics because they do not become infected by HIV-1 due to structural differences between several human and mouse proteins required for HIV-1 replication. This has limited their use for in vivo assessment of anti-HIV-1 therapeutics and the mechanism by which cofactors, such as illicit drug use accelerate HIV-1 replication and disease course in substance abusers. Here, we describe the development and application of two in vivo humanized mouse models that are highly sensitive and useful models for the in vivo evaluation of candidate anti-HIV therapeutics. The first model, hu-spl-PBMC-NSG mice, uses NOD-SCID IL2rγ(-/-) (NSG) mice intrasplenically injected with human peripheral blood mononuclear cells (PBMC) which develop productive splenic HIV-1 infection after intrasplenic inoculation with a replication-competent HIV-1 expressing Renilla reniformis luciferase (HIV-LucR) and enables investigators to use bioluminescence to visualize and quantitate the temporal effects of therapeutics on HIV-1 infection. The second model, hCD4/R5/cT1 mice, consists of transgenic mice carrying human CD4, CCR5 and cyclin T1 genes, which enables murine CD4-expressing cells to support HIV-1 entry, Tat-mediated LTR transcription and consequently develop productive infection. The hCD4/R5/cT1 mice develop disseminated infection of tissues including the spleen, small intestine, lymph nodes and lungs after intravenous injection with HIV-1-LucR. Because these mice can be infected with HIV-LucR expressing transmitted/founder and clade A/E and C Envs, these mouse models can also be used to evaluate the in vivo efficacy of broadly neutralizing antibodies and antibodies induced by candidate HIV-1 vaccines. Furthermore, because hCD4/R5/cT1 mice can be infected by vaginal inoculation with replication-competent HIV-1 expressing NanoLuc (HIV-nLucR)-, this mouse model can be used to evaluate the mechanisms by which substance abuse and other factors enhance mucosal transmission of HIV-1.

Vulvovaginal candidiasis: Epidemiology, microbiology and risk factors

Vulvovaginal candidiasis (VVC) is an infection caused by Candida species that affects millions of women every year. Although Candida albicans is the main cause of VVC, the identification of non-Candida albicans Candida (NCAC) species, especially Candida glabrata, as the cause of this infection, appears to be increasing. The development of VVC is usually attributed to the disturbance of the balance between Candida vaginal colonization and host environment by physiological or nonphysiological changes. Several host-related and behavioral risk factors have been proposed as predisposing factors for VVC. Host-related factors include pregnancy, hormone replacement, uncontrolled diabetes, immunosuppression, antibiotics, glucocorticoids use and genetic predispositions. Behavioral risk factors include use of oral contraceptives, intrauterine device, spermicides and condoms and some habits of hygiene, clothing and sexual practices. Despite a growing list of recognized risk factors, much remains to be elucidated as the role of host versus microorganisms, in inducing VVC and its recurrence. Thus, this review provides information about the current state of knowledge on the risk factors that predispose to VVC, also including a revision of the epidemiology and microbiology of VVC, as well as of Candida virulence factors associated with vaginal pathogenicity.

The Vaginal Acquisition and Dissemination of HIV-1 Infection in a Novel Transgenic Mouse Model Is Facilitated by Coinfection with Herpes Simplex Virus 2 and Is Inhibited by Microbicide Treatment

Epidemiological studies have demonstrated that herpes simplex virus 2 (HSV-2) infection significantly increases the risk of HIV-1 acquisition, thereby contributing to the expanding HIV-1 epidemic. To investigate whether HSV-2 infection directly facilitates mucosal HIV-1 acquisition, we used our transgenic hCD4/R5/cT1 mouse model which circumvents major entry and transcription blocks preventing murine HIV-1 infection by targeting transgenic expression of human CD4, CCR5, and cyclin T1 genes to CD4(+) T cells and myeloid-committed cells. Productive infection of mucosal leukocytes, predominantly CD4(+) T cells, was detected in all hCD4/R5/cT1 mice intravaginally challenged with an HIV-1 infectious molecular clone, HIV-Du151.2env-NLuc, which expresses an env gene (C.Du151.2) cloned from an acute heterosexually infected woman and a NanoLuc luciferase reporter gene. Lower genital tract HIV-1 infection after HIV-Du151.2env-NLuc intravaginal challenge was increased ~4-fold in hCD4/R5/cT1 mice coinfected with HSV-2. Furthermore, HIV-1 dissemination to draining lymph nodes was detected only in HSV-2-coinfected mice. HSV-2 infection stimulated local infiltration and activation of CD4(+) T cells and dendritic cells, likely contributing to the enhanced HIV-1 infection and dissemination in HSV-2-coinfected mice. We then used this model to demonstrate that a novel gel containing tenofovir disoproxil fumarate (TDF), the more potent prodrug of tenofovir (TFV), but not the TFV microbicide gel utilized in the recent CAPRISA 004, VOICE (Vaginal and Oral Interventions to Control the Epidemic), and FACTS 001 clinical trials, was effective as preexposure prophylaxis (PrEP) to completely prevent vaginal HIV-1 infection in almost half of HSV-2-coinfected mice. These results also support utilization of hCD4/R5/cT1 mice as a highly reproducible immunocompetent preclinical model to evaluate HIV-1 acquisition across the female genital tract.

IMPORTANCE

Multiple epidemiological studies have reported that genital herpes simplex virus 2 (HSV-2) infection increases the risk of HIV-1 sexual acquisition by severalfold. Understanding the underlying mechanisms by which HSV-2 facilitates HIV-1 infection and optimizing the efficacy of therapies to inhibit HIV-1 infection during HSV-2 coinfection should contribute to reducing HIV-1 transmission. Using our novel transgenic hCD4/R5/cT1 mouse model infectible with HIV-1, we demonstrated that HSV-2 infection enhances vaginal transmission and dissemination of HIV-1 infection while stimulating recruitment and activation of CD4(+) T cells and dendritic cells in the lower genital tract. HIV acquisition by hCD4/R5/cT1 mice vaginally coinfected with HSV-2 could be completely prevented in almost half the mice by preexposure prophylaxis (PrEP) with a novel gel containing tenofovir disoproxil fumarate (TDF), the tenofovir prodrug, but not with the tenofovir microbicide gel utilized in CAPRISA-004, VOICE, and FACTS-001 clinical trials. The hCD4/R5/cT1 mice represent a new preclinical mouse model to evaluate vaginal HIV-1 acquisition.

Transcriptomic analysis of vulvovaginal candidiasis identifies a role for the NLRP3 inflammasome

Treatment of vulvovaginal candidiasis (VVC), caused most frequently by Candida albicans, represents a significant unmet clinical need. C. albicans, as both a commensal and a pathogenic organism, has a complex and poorly understood interaction with the vaginal environment. Understanding the complex nature of this relationship is necessary for the development of desperately needed therapies to treat symptomatic infection. Using transcriptome sequencing (RNA-seq), we characterized the early murine vaginal and fungal transcriptomes of the organism during VVC. Network analysis of host genes that were differentially expressed between infected and naive mice predicted the activation or repression of several signaling pathways that have not been previously associated with VVC, including NLRP3 inflammasome activation. Intravaginal challenge of Nlrp3(-/-) mice with C. albicans demonstrated severely reduced levels of polymorphonuclear leukocytes (PMNs), alarmins, and inflammatory cytokines, including interleukin-1β (IL-1β) (the hallmarks of VVC immunopathogenesis) in vaginal lavage fluid. Intravaginal administration of wild-type (WT) mice with glyburide, a potent inhibitor of the NLRP3 inflammasome, reduced PMN infiltration and IL-1β to levels comparable to those observed in Nlrp3(-/-) mice. Furthermore, RNA-seq analysis of C. albicans genes indicated robust expression of hypha-associated secreted aspartyl proteinases 4, 5, and 6 (SAP4-6), which are known inflammasome activators. Despite colonization similar to that of the WT strain, ΔSAP4-6 triple and ΔSAP5 single mutants induced significantly less PMN influx and IL-1β during intravaginal challenge. Our findings demonstrate a novel role for the inflammasome in the immunopathogenesis of VVC and implicate the hypha-associated SAPs as major C. albicans virulence determinants during vulvovaginal candidiasis.

IMPORTANCE

Vaginitis, most commonly caused by the fungus Candida albicans, results in significant quality-of-life issues for all women of reproductive age. Recent efforts have suggested that vaginitis results from an immunopathological response governed by host innate immunity, although an explanatory mechanism has remained undefined. Using comprehensive genomic, immunological, and pharmacological approaches, we have elucidated the NLRP3 inflammasome as a crucial molecular mechanism contributing to host immunopathology. We have also demonstrated that C. albicans hypha-associated secreted aspartyl proteinases (SAP4-6 and SAP5, more specifically) contribute to disease immunopathology. Ultimately, this study enhances our understanding of the complex interplay between host and fungus at the vaginal mucosa and provides proof-of-principle evidence for therapeutic targeting of inflammasomes for symptomatic vulvovaginal candidiasis.

Serum interleukin-6 levels in murine models of Candida albicans infection

Two Balb/C mouse models of Candida infection were used to detect serum interleukin-6 (IL-6) responses. The first model used systemic infection by Candida albicans ATCC 10231 strain infected through the lateral tail vein of mice without any specific pretreatment. The median Candida burdens of the kidneys were 1.5 × 106 CFU/ml 24 h postinoculation (p.i.) and 1.2 × 107 CFU/ml 72 h p.i., while median serum IL-6 levels were 479.3 pg/ml and 934.5 pg/ml, respectively. The Candida burden showed significant correlation with serum IL-6 24 h p.i. (R2 = 0.6358; P = 0.0082) but not 72 h p.i.The second model was a mouse vaginitis model applying intravaginal inoculation of mice pretreated with subcutaneous estradiol-valerate (10 mg/ml) 3 days before infection. Candida cell count in vaginal lavage fluid was 2.8 × 106 CFU/ml 24 h p.i. and 1.4 × 108 CFU/ml 72 h p.i. Serum IL-6 response was detected in 4 of 15 mice 24 h p.i. and 9 of 15 mice 72 h p.i. Even the responders had low IL-6 serum levels (mean values 29.9 pg/ml and 60.1 pg/ml, respectively) not correlating with Candida cell count in vaginal lavage fluid.In conclusion, serum IL-6 had strong relationship with systemic C. albicans infection while the local C. albicans infection of the vagina led to partial, prolonged and limited serum IL-6 response.

Mice transgenic for CD4-specific human CD4, CCR5 and cyclin T1 expression: a new model for investigating HIV-1 transmission and treatment efficacy

Mice cannot be used to evaluate HIV-1 therapeutics and vaccines because they are not infectible by HIV-1 due to structural differences between several human and mouse proteins required for HIV-1 entry and replication including CD4, CCR5 and cyclin T1. We overcame this limitation by constructing mice with CD4 enhancer/promoter-regulated human CD4, CCR5 and cyclin T1 genes integrated as tightly linked transgenes (hCD4/R5/cT1 mice) promoting their efficient co-transmission and enabling the murine CD4-expressing cells to support HIV-1 entry and Tat-mediated LTR transcription. All of the hCD4/R5/cT1 mice developed disseminated infection of tissues that included the spleen, small intestine, lymph nodes and lungs after intravenous injection with an HIV-1 infectious molecular clone (HIV-IMC) expressing Renilla reniformis luciferase (LucR). Furthermore, localized infection of cervical-vaginal mucosal leukocytes developed after intravaginal inoculation of hCD4/R5/cT1 mice with the LucR-expressing HIV-IMC. hCD4/R5/cT1 mice reproducibly developed in vivo infection after inoculation with LucR-expressing HIV-IMC which could be bioluminescently quantified and visualized with a high sensitivity and specificity which enabled them to be used to evaluate the efficacy of HIV-1 therapeutics. Treatment with highly active anti-retroviral therapy or one dose of VRC01, a broadly neutralizing anti-HIV-1 antibody, almost completed inhibited acute systemic HIV-1 infection of the hCD4/R5/cT1 mice. hCD4/R5/cT1 mice could also be used to evaluate the capacity of therapies delivered by gene therapy to inhibit in vivo HIV infection. VRC01 secreted in vivo by primary B cells transduced with a VRC01-encoding lentivirus transplanted into hCD4/R5/cT1 mice markedly inhibited infection after intravenous challenge with LucR-expressing HIV-IMC. The reproducible infection of CD4/R5/cT1 mice with LucR-expressing HIV-IMC after intravenous or mucosal inoculation combined with the availability of LucR-expressing HIV-IMC expressing transmitted/founder and clade A/E and C Envs will provide researchers with a highly accessible pre-clinical in vivo HIV-1-infection model to study HIV-1 acquisition, treatment, and prevention.

In vitro Antifungal Susceptibility Patterns of Candida Albicans from HIV and AIDS Patients Attending the Nylon Health District Hospital in Douala, Cameroon

HIV and AIDS are major public health problems in Cameroon where the HIV prevalence is 5.5%. Candidiasis is the leading opportunistic mycosis in HIV and AIDS patients. The objective of this study was to determine the in vitro antifungal susceptibility pattern of Candida albicans in HIV and AIDS patients to eight antifungal agents in the Nylon Health District of Douala in Cameroon. Three hundred and four HIV and AIDS patients were recruited between March and August 2007 to participate in a cross-sectional study. All subjects who fulfilled the inclusion criteria were enrolled. Informed consent was obtained from all subjects before samples were collected. Three samples comprising oral swabs, vagina/urethra swabs and a mid-stream urine were collected from each subject. Specimens were cultured on sabouraud dextrose agar and C. albicans isolates were identified using the germ tube technique. The disk diffusion method was used for antifungal susceptibility testing using eight antifungal agents. The prevalence of candidiasis in the study population was 67.8% (95% CI: 62.5-73.1%) and that of C. albicans was 42.8% (95% CI: 37.2-48.4%). Oral swabs had the highest prevalence of C. albicans followed by vaginal/urethral samples (52.6% vs. 29.7% respectively). Forty (30.8%) subjects had C. albicans infection at more than one collection site. There was a statistically significant difference in the infectivity of C. albicans with age, sex and site of infection (P<0.05). C. albicans isolates were most sensitive to ketoconazole (80%) followed by econazole (64.6%) while fluconazole and 5-flurocytosin recorded the poorest sensitivities (22.9% vs 24.6%, respectively). There was a statistically significant difference in the sensitivity pattern of antifungal agents with respect to the site of isolation of the organism (P<0.05). Ketoconazole is the drug of choice for the treatment of C. albicans infection in HIV and AIDS patients in the Nylon Health District of Douala, Cameroon.

Protective role of α-galactosylceramide-stimulated natural killer T cells in genital tract infection with Chlamydia muridarum

Natural killer T (NKT) cells are a unique lymphocyte subpopulation which has an important role in the response to microbial pathogens. In this study, we used α-galactosylceramide (α-GalCer), a specific ligand of NKT cells, to enhance NKT response and examine its effect on host defense against genital tract Chlamydia muridarum infection. The results showed that α-GalCer treatment before infection led to reduced pathological changes and bacterial burden in the genital tract. Moreover, α-GalCer-treated mice showed greater local Th1 cytokine production [interferon γ (IFN-γ) and interleukin 12 (IL-12)] in local lymph node cells and genital tissues following challenge infection compared with untreated mice, as well as an enhanced level of IFN-γ production by NK and T cells. In addition, NKT cells in the mice with genital tract C. muridarum infection, unlike those from naïve mice, showed a polarized IFN-γ production. These results suggest a promoting role of NKT cells on type 1 T cell immune response and host resistance to Chlamydia in genital tract infection.

Cytokines in the host response to Candida vaginitis: Identifying a role for non-classical immune mediators, S100 alarmins

Vulvovaginal candidiasis (VVC), caused by Candida albicans, affects a significant number of women during their reproductive years. More than two decades of research have been focused on the mechanisms associated with susceptibility or resistance to symptomatic infection. Adaptive immunity by Th1-type CD4(+) T cells and downstream cytokine responses are considered the predominant host defense mechanisms against mucosal Candida infections. However, numerous clinical and animal studies have indicated no or limited protective role of cells and cytokines of the Th1 or Th2 lineage against vaginal infection. The role for Th17 is only now begun to be investigated in-depth for VVC with results already showing significant controversy. On the other hand, a clinical live-challenge study and an established animal model have shown that a symptomatic condition is intimately associated with the vaginal infiltration of polymorphonuclear leukocytes (PMNs) but with no effect on vaginal fungal burden. Subsequent studies identified S100A8 and S100A9 alarmins as key chemotactic mediators of the acute PMN response. These chemotactic danger signals appear to be secreted by vaginal epithelial cells upon interaction and early adherence of Candida. Thus, instead of a putative immunodeficiency against Candida involving classical immune cells and cytokines of the adaptive response, the pathological inflammation in VVC is now considered a consequence of a non-productive innate response initiated by non-classical immune mediators.

Th17 cells and IL-17 in protective immunity to vaginal candidiasis

BACKGROUND

Th17 cells play a major role in coordinating the host defence in oropharyngeal candidiasis. In this study we investigated the involvement of the Th17 response in an animal model of vulvovaginal candidiasis (VVC).

METHODS

To monitor the course of infection we exploited a new in vivo imaging technique.

RESULTS

i) The progression of VVC leads to a strong influx of neutrophils in the vagina soon after the challenge which persisted despite the resolution of infection; ii) IL-17, produced by vaginal cells, particularly CD4 T cells, was detected in the vaginal wash during the infection, reaching a maximum 14 days after the challenge; iii) The amount and kinetics of IL-23 in vaginal fluids were comparable to those in vaginal cells; iv) The inhibition of Th17 differentiation led to significant inhibition of IL-17 production with consequent exacerbation of infection; v) An increased production of βdefensin 2 was manifested in cells of infected mice. This production was strongly reduced when Th17 differentiation was inhibited and was increased by rIL-17 treatment.

CONCLUSIONS

These results imply that IL-17 and Th17, along with innate antimicrobial factors, have a role in the immune response to vaginal candidiasis.

Local expression of vaginal Th1 and Th2 cytokines in murine vaginal candidiasis under different immunity conditions

To investigate the expression of vaginal Th1 and Th2 cytokines in rats with experimental vaginal candidiasis under different immune conditions, ICR murine vaginal candidiasis model was established and immno-suppressed murine models of vaginal cadidiasis were established in estrogen-treated mice. Non-estrogen-treated mice were used as controls. The mRNA level of Th1 (IL-2)/Th2 (IL-4, IL-10, TGF-beta1) cytokines in murine vaginal tissues was determined by RT-PCR. The cykotine in local tissues was increased to different extent under normal immune condition. IL-2 mRNA was increased during early stage of infection, while IL-10 was increased transiently during late stage of infection. TGF-beta1 production was found to be increased persistently. At same time, the expression of IL-2 mRNA was suppressed in immno-suppressed group, and the level of IL-4, IL-10, and TGF-beta1 were higher than the normal immunity group to different degree during infection. The high level of IL-2 mRNA during early stage of infection was associated with clearance of mucosal Candidia albicans (C. albicans), and its expression suppressed leading to decreased clearance of mucosal C. albican in immuno-suppression. The over-expression of IL-4 and IL-10 could significantly enhance the susceptibility to C. albicans infection in mice.

Local Th1/Th2 cytokine expression in experimental murine vaginal candidiasis

In order to investigate the expression of Th1 and Th2 cytokines in the vaginal candidiasis caused by Candida, the fungal vaginitis model was established in female ICR mice by intravaginal inoculation of suspension of C. albicans after the animals were pretreated with estradiol. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the expression of IL-2, IL-4, IL-10 and TGF-beta1 in the vagina in the mice of different groups at different time points after the beginning of the experiment. The average expression level of IL-2 mRNA in group D (estrogen-treated mice) was significantly higher than that in groups H (estrogen-untreated mice) and I (control group) on the day 2. The average expression level of IL-4 mRNA in group D was significantly higher than that in groups I and H on the day 5. The average expression level of IL-10 mRNA in group D was significantly higher than that in groups H and I from day 7 to 11. The average expression level of TGF-beta1 mRNA in group D was significantly higher than that in groups H and I at all time points. It was concludes that the high-level expression of IL-2 mRNA during early infection was associated with clearance of mucosal C. albicans, and the high-level expression of IL-10 mRNA during late stage of the infection was related to susceptibility to infection. TGF-beta1 may play a predominant role when the virtual absence of changes in other Th-type cytokines during infection.

The case for extrathymic development of vaginal T lymphocytes

The vaginal tract mucosa is populated by a small, yet phenotypically diverse and functionally significant, subset of T cells that plays a major role in local cell-mediated immunity. Although phenotypic and functional characteristics of vaginal T cells have received some attention in recent years, little is known about the development of this cell population. In this mini review, the developmental origins of vaginal T cells are traced from published work related to vaginal T cells, the vaginal mucosa environment and vaginal tract infection animal models. A CD3(+)TCR(+)CD2(+)CD5(+)B220(-) (CD3(+)B220(-)) subpopulation, which is mostly CD4(+), makes up 30-40% of vaginal T lymphocytes. This population consists of a TCRalphabeta(+) subset and TCRgammadelta(+) subset. While CD3(+)B220(-)TCRalphabeta(+) vaginal T cells exhibit phenotypic and functional properties consistent with that of peripheral T cells, CD3(+)B220(-)TCRgammadelta(+) vaginal T cells exhibit unique phenotypic and functional features that set them apart from other TCRgammadelta(+) T cell subsets populating the periphery or other mucosal areas. The vaginal mucosa is populated also by CD3(+)TCRalphabeta(+)CD4(-)/8(-)B220(+)CD2(-)CD5(-) T cells (CD3(+)B220(+)) whose relative predominance increases significantly in systemic T cell deficiency. This subset is generally unresponsive to TCR-mediated stimuli and expresses high levels of CD25, perhaps indicative of a regulatory role. Current data suggest that, while CD3(+)B220(-) vaginal T cells are mostly thymic in origin, CD3(+)TCRalphabeta(+)B220(+) cells are exclusively extrathymic.

Tracking the elusive lymphocyte: methods of detection during adoptive immunotherapy

Adoptive immunotherapy is an attractive cancer treatment modality due to its capacity to target primary and metastatic lesions with large numbers of tumor-reactive, cytotoxic lymphocytes. The inability of fully armed lymphocytes to traffic into sites of tumor has been proposed as a causal factor for the minimal success observed clinically with this type of immunotherapy. The study of lymphocyte trafficking during adoptive immunotherapy has been limited, despite the existence of a variety of tracking methods. In murine models that simulate adoptive immunotherapy, the use of congenic mice and cell tracking dyes can be used to elucidate lymphocyte trafficking behavior. The continued development of novel technologies will further contribute to this expanding area of research.

Candidiasis--do we need to fight or to tolerate the Candida fungus?

Candidiases, infections caused by germination forms of the Candida fungus, represent a heterogeneous group of diseases from systemic infection, through mucocutaneous form, to vulvovaginal form. Although caused by one organism, each form is controlled by distinct host immune mechanisms. Phagocytosis by polymorphonuclears and macrophages is generally accepted as the host immune mechanism for Candida elimination. Phagocytes require proinflammatory cytokine stimulation which could be harmful and must be regulated during the course of infection by the activity of CD8+ and CD4+ T cells. In the vaginal tissue the phagocytes are inefficient and inflammation is generally an unwanted reaction because it could damage mucosal tissue and break the tolerance to common vagina antigens including the otherwise saprophyting Candida yeast. Recurrent form of vulvovaginal candidiasis is probably associated with breaking of such tolerance. Beside the phagocytosis, specific antibodies, complement, and mucosal epithelial cell comprise Candida eliminating immune mechanisms. They are regulated by CD4+ and CD8+ T cells which produce cytokines IL-12, IFN-gamma, IL-10, TGF-beta, etc. as the response to signals from dendritic cells specialized to sense actual Candida morphotypes. During the course of Candida infection proinflammatory signals (if initially necessary) are replaced successively by antiinflammatory signals. This balance is absolutely distinct during each candidiasis form and it is crucial to describe and understand the basic principles before designing new therapeutic and/or preventive approaches.

Susceptibility to vaginal candidiasis under different conditions in mice

In order to study the susceptibility of murine vaginal mucosa to Candida albicans under different conditions, vaginal lavage fluid and vaginal tissue of mice were observed and compared between murine models with normal immune system (estrogen-treated mice) and immunosuppressed murine model, and between primary infection model of vaginal candidiasis and secondary infection one. The average level of colony forming unit (CFU) from the immuosuppressed group was higher than that from estrogen-treated group at each time point and the peak time was delayed. The differences between the two groups were statistically significant (P < 0.05) from the fourth day after inoculation. A significant difference existed in the average level of CFU between the control group and the estrogen-treated group (P < 0.05), and between the control group and the immuosuppressed group (P < 0.01). It was concluded that the vaginal mucosa from the immunosuppressed mice is more susceptible to Candida albicans and no difference is found in susceptibility between mice with primary infection and secondary infection.

History and update on host defense against vaginal candidiasis

Vulvovaginal candidiasis (VVC), caused by Candida albicans, remains a significant problem in women of childbearing age. While cell-mediated immunity is considered the predominant host defense mechanism against mucosal candidal infections, two decades of research from animal models and clinical studies have revealed a lack of a protective role for adaptive immunity against VVC caused by putative immunoregulatory mechanisms. Moreover, natural protective mechanisms and factors associated with susceptibility to infection have remained elusive. That is until recently, when through a live challenge model in humans, it was revealed that protection against vaginitis coincides with a non-inflammatory innate presence, whereas symptomatic infection correlates with a neutrophil infiltrate in the vaginal lumen and elevated fungal burden. Thus, instead of VVC being caused by a putative deficient adaptive immune response, it is now being considered that symptomatic vaginitis is caused by an aggressive innate response.

Characterization of CD8+ T cells and microenvironment in oral lesions of human immunodeficiency virus-infected persons with oropharyngeal candidiasis

Oropharyngeal candidiasis (OPC), the most common oral infection in human immunodeficiency virus-positive persons, correlates with reduced blood CD4+ T cells. In those with OPC, CD8+ T cells accumulate at the lamina propria-epithelium interface at a distance from the organism at the outer epithelium. The present study aimed to characterize the tissue-associated CD8+ T cells and tissue microenvironment in both OPC+ and OPC- persons. The results show that the majority of CD8+ T cells possess the alphabeta T-cell receptor, the thymus-derived alphabeta CD8 antigen heterodimer, and similar levels of the alpha(4)beta(7), alpha(4)beta(1), and alpha(e)beta(7) homing receptors. Studies to evaluate the tissue microenvironment showed that in OPC+ persons, the adhesion molecule for T cells to enter mucosa, mucosal addressin cell adhesion molecule, is significantly increased, whereas E-cadherin, which allows T cells to migrate through mucosa, is significantly decreased compared to OPC- persons. These results continue to support a role for CD8+ T cells against OPC under conditions of reduced numbers of CD4+T cells, with susceptibility to infection potentially associated with a dysfunction in mucosal CD8+ T-cell migration by reduced tissue-associated E-cadherin.

Asymmetric antibodies (AAb) in the female reproductive tract

Vaginal mucosa has been shown to play an important role in fertility, since several changes during the estrous cycle determine fertility and pregnancy outcome. The contribution of vaginal fluid IgG antibodies (Abs) to these changes is not fully characterized. Asymmetric Abs (AAb) are a subpopulation of IgG Abs bearing a carbohydrate residue in only one Fab region of the molecule, being therefore functionally univalent and unable to trigger immunological mechanisms tending to destroy the antigens. Here, we investigated the presence of AAb in vaginal secretions of virgin mice. Vaginal fluids were extracted from CBA/J female, where asymmetric IgG molecules were characterized by differential ELISA tests. Additionally, the phenotype of vaginal lymphocytes (VL) was analyzed by flow cytometry. Our data indicate a variation in the percentage of AAb during estrous cycle, since we observed a significant increase in asymmetric IgG molecules levels after ovulation. Regarding the AAbs isotypes, we identified IgG1 as the principal component of the synthesized AAbs. Eighty percent of the AAbs were directed against normal flora, and about 20% of them reacted with vaginal epithelium antigens. Flow cytometry studies revealed TCRalphabeta and gammadelta populations, but a lack of CD8+ T-cells in vaginal mucosa. Since we found a high concentration of AAbs in murine vaginal secretions during metestrus and AAbs were previously found to be protective, it is tempting to speculate that AAbs would provide protection of normal flora in the vaginal lumen. Additionally, we observed that the levels of AAbs decrease when susceptibility to infection in mice occurs at proestrus/estrus, further suggesting a protective role for AAbs.

Immunity in vaginal candidiasis

PURPOSE OF REVIEW

Vulvovaginal candidiasis and recurrent vulvovaginal candidiasis remain a significant problem in women of child-bearing age. While host defense mechanisms against infection are poorly understood, the most recent studies continue to challenge dogma relative to anti-Candida immunity at other mucosal sites that is normally associated with T helper 1-type CD4 T cells.

RECENT FINDINGS

Four studies comprise the latest findings in host defense against vulvovaginal candidiasis. The first from an animal model provided the most definitive data to date for the lack of involvement by systemic or local T-cell-mediated immunity. The second study confirmed a limited role for antibodies in vaginal candidiasis; similar to past studies, systemic and local Candida-specific antibodies in women with vulvovaginal candidiasis were either similar or elevated compared with controls. The third study from a cohort of adolescents provided evidence for some form of local protective immunity based on high asymptomatic vaginal fungal burden with low incidence rate of vulvovaginal candidiasis. This was addressed more specifically through a natural history protocol involving an intravaginal challenge with live Candida. Results showed a strong correlation between infiltration of polymorphonuclear neutrophils and symptomatic vulvovaginal candidiasis, with no evidence of an inflammatory response in those protected against infection.

SUMMARY

Instead of vulvovaginal candidiasis being caused by defective or dysfunctional CD4 T helper 1-type cell-mediated immune reactivity, data suggest that symptomatic vulvovaginal candidiasis is associated with an aggressive response by polymorphonuclear neutrophils, whereas protection appears to be innate and noninflammatory. The role for innate immunity in both protection against, and promotion of, symptomatic vulvovaginal candidiasis is paradigm changing.

Estrogen-dependent induction of persistent vaginal candidosis in naïve mice

The capacity of estrogen to induce vaginal candidosis (VC) in the absence of previous or concurrent Candida albicans infections was examined. Adult female Balb/c mice were evaluated for vaginal C. albicans burden, C. albicans-specific delayed type hypersensitivity (DTH) responses and vaginal lymphocyte population kinetics at several time-points while receiving weekly injections of 0.5 mg estrogen. Estrogen treatment resulted in the appearance of significant levels of C. albicans vaginal colonization, which persisted for a period of 4 weeks. A marked suppression of DTH responses mounted against subsequent C. albicans challenge was observed. Absolute number of vaginal T lymphocytes gradually increased by several folds especially at weeks 5-6 following the start of estrogen treatment. These results clearly indicate that estrogen, independent of other predisposing factors, is capable of perturbing the commensal relationship between the host and the fungus, which results in the induction of persistent VC.

Immunopathogenesis of oropharyngeal candidiasis in human immunodeficiency virus infection

Oropharyngeal and esophageal candidiases remain significant causes of morbidity in human immunodeficiency virus (HIV)-infected patients, despite the dramatic ability of antiretroviral therapy to reconstitute immunity. Notable advances have been achieved in understanding, at the molecular level, the relationships between the progression of HIV infection, the acquisition, maintenance, and clonality of oral candidal populations, and the emergence of antifungal resistance. However, the critical immunological defects which are responsible for the onset and maintenance of mucosal candidiasis in patients with HIV infection have not been elucidated. The devastating impact of HIV infection on mucosal Langerhans' cell and CD4(+) cell populations is most probably central to the pathogenesis of mucosal candidiasis in HIV-infected patients. However, these defects may be partly compensated by preserved host defense mechanisms (calprotectin, keratinocytes, CD8(+) T cells, and phagocytes) which, individually or together, may limit Candida albicans proliferation to the superficial mucosa. The availability of CD4C/HIV transgenic mice expressing HIV-1 in immune cells has provided the opportunity to devise a novel model of mucosal candidiasis that closely mimics the clinical and pathological features of candidal infection in human HIV infection. These transgenic mice allow, for the first time, a precise cause-and-effect analysis of the immunopathogenesis of mucosal candidiasis in HIV infection under controlled conditions in a small laboratory animal.

Immune Regulation and Its Role in the Pathogenesis of Candida Vaginitis

The pathogenesis of vulvovaginal candidiasis, which is caused by Candida albicans, is poorly understood. Despite a strong protective role for cell-mediated immunity (CMI) against other mucosal candidal infections, numerous studies in humans and most animal models have revealed little to no role for CMI or other forms of acquired immunity against vaginal candidal infections. Studies suggest that this may be because of immunoregulatory mechanisms that inhibit more profound adaptive immune responses rather than the simple lack of responsiveness. Such regulatory mechanisms significantly influence the pathogenesis of Candida vaginitis.

A unique population of extrathymically derived alpha beta TCR+CD4-CD8- T cells with regulatory functions dominates the mouse female genital tract

A better understanding of the regulatory role of genital tract T cells is much needed. In this study, we have analyzed the phenotype, distribution, and function of T lymphocytes in the female genital tract of naive, pregnant, or Chlamydia trachomatis-infected C57BL/6 mice. Unexpectedly, we found that the dominant lymphocyte population (70-90%) in the genital tract was that of CD3(+)alphabetaTCR(int)CD4(-)CD8(-) T cells. Moreover, these cells were CD90(low) but negative for the classical T cell markers CD2 and CD5. The CD3(+)B220(low) cells were NK1.1 negative and found in nude mice as well as in mice deficient for MHC class II, beta(2)-microglobulin, and CD1, indicating extrathymic origin. They dominated the KJ126(+)Vbeta8.2(+) population in the genital tract of DO11.10 OVA TCR-transgenic mice, further supporting the idea that the CD3(+)B220(low) cells are truly T cells. The function of these T cells appeared not to be associated with immune protection, because only CD4(+) and CD8(+) T cells increased in the genital tract following chlamydial infection. Notwithstanding this, the infected, as well as the uninfected and the pregnant, uterus was dominated by a high level of the CD3(+)CD4(-)CD8(-)B220(low) cells. Following in vitro Ag or polyclonal stimulation of the CD3(+)CD4(-)CD8(-)B220(low) cells, poor proliferative responses were observed. However, these cells strongly impaired splenic T cell proliferation in a cell density-dependent manner. A large fraction of the cells expressed CD25 and produced IFN-gamma upon anti-CD3 plus anti-CD28 stimulation, arguing for a strong regulatory role of this novel T cell population in the mouse female genital tract.

Multiple experimental designs to evaluate the role of T-cell-mediated immunity against experimental vaginalCandida albicansinfection

Studies to date suggest a limited protective role for Candida-specific Th1-type cell-mediated immunity (CMI) against Candida albicans vaginitis, despite protection against other mucosal Candida infections. Recent evidence suggests this may be due to immunoregulatory mechanisms that inhibit a more profound CMI response against C. albicans vaginal infections. The present study was designed to conduct an evaluation of the protective role of CMI against experimental C. albicans vaginitis using multiple approaches, including the use of T-cell-immunodeficient (SCID, Nude) and knockout (CD4) mice and several immunization designs in immunocompetent mice. Results showed, with few exceptions, that most T-cell-immunodeficient or knockout mice had a vaginal fungal burden similar to that of wild-type strains throughout the observation period. In addition, no correlation was observed between vaginal T-helper and proinflammatory cytokines and fungal burden, suggesting a generalized state of immunoregulation. Evaluation of the effects of various immunization designs that included different Candida antigens, routes of delivery and strains of mice yielded no protection against vaginal candidiasis. These studies provide further evidence of a lack of a protective role of T cells against C. albicans vaginitis, and continue to support the concept of immunoregulation against vaginal CMI responses.

Vaginal T lymphocyte population kinetics during experimental vaginal candidosis: evidence for a possible role of CD8+ T cells in protection against vaginal candidosis

Vaginal candidosis represents a significant health problem to women of childbearing age worldwide. It has been postulated that localized T cells play a role in protection against vaginal candidosis. In an attempt to evaluate the role of vaginal T cells in protection against vaginal candidosis, T cell population kinetics was evaluated using an oestrogen-dependent vaginal candidosis murine model. Vaginal T lymphocytes were isolated at different time points post C. albicans inoculation, viable cells were enumerated, phenotypically analysed for the expression of CD3, CD4 and CD8 T cell markers and absolute numbers of T cell subsets were calculated. Oestrogen-induced persistence of vaginal candidosis resulted in a significant increase in the total number of vaginal lymphocytes within 24-48 h post infection; increased vaginal lymphocyte numbers persisted throughout the infection period. The number of CD3+ T cells dramatically increased following C. albicans administration and was maintained at high levels throughout the infection period. The majority of CD3+ T cells were of the CD8+ type; however, considerable numbers of both CD4+ T cells and CD4+CD8+ T cells were also observed throughout the infection period. The considerable and persistent increase in vaginal T cell numbers in general and that of CD8+ T cells in particular are evidence of the possible role played by localized T cells in protection against vaginal candidosis.

Immunity to Candida

Candida species are commensal fungal organisms as well as opportunistic pathogens of mucosal tissues. From the commensal relationship, most healthy individuals have demonstrable Candida-specific immunity. In immunocompromised persons, however, fungal infections caused primarily by C. albicans often occur. In HIV disease, up to 90% of HIV+ persons will have a symptomatic episode of oropharyngeal candidiasis (OPC) sometime during progression to AIDS, many of which become recurrent. In contrast, vulvovaginal candidiasis (VVC) and systemic Candida infections (candidaemia) are much less common during HIV disease, indicating the diversity and compartmentalization of the host response to Candida. Both innate resistance and acquired immunity play some role in maintaining C. albicans in the commensal state and protecting the systemic circulation. Polymorphonuclear leukocytes (PMNL) are critical for protection against systemic infections, whereas cell-mediated immunity (CMI) by Th1-type CD4+ T-cells is important for protection against mucosal infections. However, there is a discordant role for CMI at the vaginal versus oral mucosa, whereas little to no role for local or systemic CMI is evident at the vaginal mucosa. In contrast, there is a strong correlation between reduced blood CD4+ cells and the incidence of OPC, but it remains unclear whether systemic or local CMI is more important. Evaluation of systemic CMI in a cohort of HIV+ individuals with and without mucosal candidiasis revealed that Candida-specific CMI is not different between HIV+ persons with OPC or VVC and HIV- persons. Thus, the correlation of reduced CD4+ cell numbers to OPC may be explained by the requirement for a threshold number of systemic CD4+ cells to protect the oral mucosa together with the status of local immunity. Indeed, HIV+ persons with and without OPC had a Th2-type salivary cytokine profile suggestive of susceptibility to Candida infection compared with a protective Th0/Th1-type profile in HIV- persons. Candida-specific antibodies, although present, are controversial relative to a role in protection or eradication of infection. While studies of mucosal innate resistance are limited, we recently found that epithelial cells from saliva and vaginal lavages of healthy individuals inhibit the growth of Candida in vitro. This epithelial cell anti-Candida activity requires cell contact by viable cells with no role for soluble factors, including saliva. Interestingly, oral epithelial cells from HIV+ persons with OPC had significantly reduced activity, indicating some protective role for the epithelial cells. Taken together, these data suggest that immunity to Candida is site-specific, compartmentalized and involves innate and/or acquired mechanisms from systemic and/or local sources.

The protective immune response against vaginal candidiasis: lessons learned from clinical studies and animal models

Recurrent vulvovaginal candidiasis (RVVC) is a significant problem in women of childbearing ages and is caused by Candida albicans, a commensal organism of the intestinal and reproductive tracts. As a result of this commensalism, most healthy individuals have demonstrable Candida-specific adaptive immunity that is considered protective. In women with RVVC, a deficiency/dysfunction of this protective immunity is postulated to affect susceptibility to infection. Although cell-mediated immunity (CMI) is considered important for protection against mucosal candidal infections, little is understood about specific host defenses that are important at the vaginal mucosa. Studies to date suggest that a compartmentalized local, rather than systemic, immunity is important for defense against vaginitis. This review will summarize the current state of knowledge regarding protective host defense mechanisms against vaginal C. albicans infections both from clinical studies and animal models. From these data, hypotheses are presented for what host defense mechanisms appear important for resistance/susceptibility to vaginal infection.

Immune cell-mediated protection against vaginal candidiasis: evidence for a major role of vaginal CD4(+) T cells and possible participation of other local lymphocyte effectors

The protective roles of different lymphocyte subsets were investigated in a rat vaginal candidiasis model by adoptive transfer of vaginal lymphocytes (VL) or sorted, purified CD3(+) T cells, CD4(+) or CD8(+) T cells, or CD3(-) CD5(+) B cells from the vaginas of naïve or immune rats following three rounds of Candida albicans infection. The adoptive transfer of total VL from nonimmune animals did not alter the course of vaginal candidiasis of the recipient rats. In contrast, the animals receiving total VL or CD3(+) T cells from immune rats showed a highly significant acceleration of fungus clearance compared with animals which received nonimmune VL. The animals with vaginal CD3(-) CD5(+) B cells transferred from immune rats also had fewer Candida CFU than the controls, but fungal clearance was significantly retarded with respect to the animals administered immune T cells. Sorted, purified CD4(+) and CD8(+) vaginal T cells from immune rats were also adoptively transferred to naïve animals. Although both populations were seen to accelerate the clearance of the fungus from the vagina, CD4(+) T cells were much more effective than CD8(+) T cells. Overall, there was no difference between the antifungal effects of immune vaginal CD4(+) T cells and those achievable with the transfer of whole, immune VL. Histological observations of the vaginal tissues of rats with adoptively transferred immune T cells demonstrated a remarkable accumulation of lymphocytes in the subepithelial lamina propria and also infiltrating the mucosal epithelium. These results strongly suggest that distinct vaginal lymphocyte subsets participate in the adaptive anti-Candida immunity at the vaginal level, with the vaginal CD4(+) T cells probably playing a major role.

New immunotherapeutic strategies to control vaginal candidiasis

The widespread occurrence of mucosal infections caused by Candida, in particular recurrent vulvovaginal candidiasis among fertile-age women, together with the paucity of safe candidacidal antimycotics, have prompted a great number of investigations into the immunotherapy of candidal vaginitis. This article will discuss three different experimental approaches demonstrated to be potentially transferable to human disease: (1) the use of antibodies against well-defined cell-surface adhesins or enzymes; (2) the generation of yeast killer-toxin-like candidacidal anti-idiotypic antibodies and their engineered molecular derivatives (e.g. single chains, peptides); and (3) the generation of therapeutic vaccines and immunomodulators.

Resistance of T-cell receptor delta-chain-deficient mice to experimental Candida albicans vaginitis

Conditions consistent with tolerance or immunoregulation have been observed in experimental Candida albicans vaginal infections. The present study investigated the role of gamma/delta T cells in experimental vaginal candidiasis. Results showed that T-cell receptor delta-chain-knockout mice had significantly less vaginal fungal burden when compared to wild-type mice, suggesting an immunoregulatory role for gamma/delta T cells in Candida vaginitis.

Cell adhesion molecule and lymphocyte activation marker expression during experimental vaginal candidiasis

Cell-mediated immunity by Th1-type CD4(+) T cells is the predominant host defense mechanism against mucosal candidiasis. However, studies using an estrogen-dependent murine model of vaginal candidiasis have demonstrated little to no change in resident vaginal T cells during infection and no systemic T-cell infiltration despite the presence of Candida-specific systemic Th1-type responses in infected mice. The present study was designed to further investigate these observations by characterizing T-cell activation and cell adhesion molecule expression during primary and secondary C. albicans vaginal infections. While flow cytometry analysis of activation markers showed some evidence for activation of CD3(+) draining lymph node and/or vaginal lymphocytes during both primary and secondary vaginal Candida infection, CD3(+) cells expressing the homing receptors and integrins alpha(4)beta(7), alpha(M290)beta(7), and alpha(4)beta(1) in draining lymph nodes of mice with primary and secondary infections were reduced compared to results for uninfected mice. At the local level, few vaginal lymphocytes expressed integrins, with only minor changes observed during both primary and secondary infections. On the other hand, immunohistochemical analysis of vaginal cell adhesion molecule expression showed increases in mucosal addressin cell adhesion molecule 1 and vascular cell adhesion molecule 1 expression during both primary and secondary infections. Altogether, these data suggest that although the vaginal tissue is permissive to cellular infiltration during a vaginal Candida infection, the reduced numbers of systemic cells expressing the reciprocal cellular adhesion molecules may preempt cellular infiltration, thereby limiting Candida-specific T-cell responses against infection.

Suppression of type 2 NO-synthase activity in macrophages by Candida albicans

Macrophages (Mphi) are important for the defence against experimental disseminated candidiasis. Nitric oxide (NO) generated by the inducible isoform of NO-synthase (iNOS or NOS2) is thought to contribute to candidacidal effector functions by activated Mphi. In vitro, however, Mphi cannot control the growth and hyphal formation of Candida (C.) albicans. Using mouse peritoneal exudate Mphi stimulated with IFN-gamma and LPS, we examined the effect of C. albicans on NO synthesis, NOS2 enzyme activity and macrophage survival. C. albicans effectively inhibited the production of NO via suppression of total NOS2 protein and enzyme activity. Hyphal formation of C. albicans and direct interaction with host cells was required for maximum inhibition of NO production, whereas non-filamentous C. albicans mutants released soluble products that effected only partial inhibition. Ultimately, Mphi underwent apoptotic cell death after infection with C. albicans wild-type strains capable of hyphal formation, indicated by loss of the mitochondrial membrane potential and onset of chromatin degradation. NO suppression and Mphi killing are potent activities of C. albicans that may augment virulence of C. albicans.

Local Th1/Th2 cytokine production during experimental vaginal candidiasis: potential importance of transforming growth factor-beta

Host defense mechanisms against vaginal Candida albicans infections are poorly understood. Despite the protective role of T helper (Th)1-type cell-mediated immunity (CMI) against mucosal C. albicans infections, studies using an estrogen-dependent murine model of vaginal candidiasis have shown a lack of effect of systemic Th1-type CMI against a vaginal C. albicans infection, and a lack of changes in local T cells during infection. In the present study, the local Thl- (interleukin [IL]-2, interferon [IFN]-gamma and IL-12) and Th2- (IL-4, IL-10 and transforming growth factor [TGF]-beta1) type cytokines were evaluated in vaginal tissue during an experimental C. albicans infection. Results showed constitutive expression of TGF-beta1 in vaginal tissue of naive mice that was two-fold higher than the levels of the other cytokines examined. These high levels of TGF-beta1 were further increased as a result of pseudoestrus and/or infection, and were corroborated at the messenger RNA level. Furthermore, the levels of TGF-beta in naive or infected mice were significantly higher in the vagina compared to other areas of the genital tract. Finally, TGF-beta1 predominated as well in the draining, but not non-draining, lymph nodes during infection. These results suggest that TGF-beta1, a potent immunoregulatory cytokine, may be important in the lack of demonstrable CMI at the vaginal mucosa against C. albicans.

Evidence for a unique expression of CD4 on murine vaginal CD4+ cells

Mucosal cell-mediated immunity (CMI) by CD4+ T cells is postulated to be important for host defence against several vaginal pathogens. In addition to the recognized phenotypic distinctions of resident vaginal T lymphocytes, we recently provided evidence by fluorescence-activated cell sorter (FACS) that murine vaginal CD4+ T lymphocytes, are differentially recognized by two epitope-distinct anti-CD4 antibodies, suggesting that the CD4 protein on vaginal CD4+ cells is atypically expressed. In the present study, we confirm this by FACS and immunohistochemistry under non-denaturing conditions using two additional anti-CD4 antibodies. However, positive immunohistochemical staining of vaginal CD4+ cells under denaturing conditions revealed that the CD4 epitope in question is indeed present within the CD4 protein. Using reverse transcription polymerase chain reaction, amplification of CD3, T-cell receptor-beta (TCR-beta), and TCR-delta mRNA from lymph node and vaginal tissue, and CD4 mRNA from lymph node tissue was demonstrable. In contrast, amplification of CD4 mRNA from vaginal tissue, vaginal enriched lymphoid cells, or a purified (FACS-sorted) population of vaginal-specific CD4+ cells using two distinct primer sets was not demonstrable. Altogether, our results provide evidence that the CD4 protein on vaginal CD4+ T cells is conformationally distinct compared with its systemic counterpart, either as a result of a unique CD4 mRNA sequence or from a stable interaction of soluble CD4 with the surface of vaginal T cells.

Local production of chemokines during experimental vaginal candidiasis

Recurrent vulvovaginal candidiasis, caused by Candida albicans, is a significant problem in women of childbearing age. Although cell-mediated immunity (CMI) due to T cells and cytokines is the predominant host defense mechanism against C. albicans at mucosal tissue sites, host defense mechanisms against C. albicans at the vaginal mucosa are poorly understood. Based on an estrogen-dependent murine model of vaginal candidiasis, our data suggest that systemic CMI is ineffective against C. albicans vaginal infections. Thus, we have postulated that local immune mechanisms are critical for protection against infection. In the present study, the kinetic production of chemokines normally associated with the chemotaxis of T cells, macrophages (RANTES, MIP-1alpha, MCP-1), and polymorphonuclear neutrophils (MIP-2) was examined following intravaginal inoculation of C. albicans in estrogen-treated or untreated mice. Results showed significant increases in MCP-1 protein and mRNA in vaginal tissue of infected mice as early as 2 and 4 days postinoculation, respectively, that continued through a 21-day observation period, irrespective of estrogen status. No significant changes were observed with RANTES, MIP-1alpha, or MIP-2, although relatively high constitutive levels of RANTES mRNA and MIP-2 protein were observed. Furthermore, intravaginal immunoneutralization of MCP-1 with anti-MCP-1 antibodies resulted in a significant increase in vaginal fungal burden early during infection, suggesting that MCP-1 plays some role in reducing the fungal burden during vaginal infection. However, the lack of changes in leukocyte profiles in vaginal lavage fluids collected from infected versus uninfected mice suggests that MCP-1 functions to control vaginal C. albicans titers in a manner independent of cellular chemotactic activity.

Nasal immunization of mice with human papillomavirus type 16 (HPV-16) virus-like particles or with the HPV-16 L1 gene elicits specific cytotoxic T lymphocytes in vaginal draining lymph nodes

Human papillomavirus type 16 (HPV-16) infects the genital tract and is closely associated with the development of cervical cancer. HPV-16 initiates infection at the genital mucosal surface; thus, mucosal immune responses are likely to contribute to defense against HPV-16 infection. However, little information is available regarding the induction of immune responses in the genital tract mucosa. In this study, we evaluated the potential of intranasally administered papillomavirus vaccines to elicit both systemic and vaginal immune responses. HPV-16 virus-like particles (VLPs) produced by self-assembly of L1 protein and the HPV-16 L1 gene cloned into a mammalian expression vector were used as vaccines. Intranasally administered VLPs induced serum immunoglobulin G (IgG) and vaginal IgA secretory antibodies. Very weak serum IgG and vaginal IgA responses were found after DNA immunization. Both splenic and vaginal lymphocytes could be activated by intranasal immunization with VLPs and the HPV-16 L1 gene. Activated CD4(+) Th1-like T cells were shown to synthesize gamma interferon, and activated CD8(+) T cells were demonstrated to be cytotoxic.

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 management of superficial candidiasis

Superficial Candida infection includes several common conditions, most often related to some underlying local or systemic predisposition. Appropriate identification of the pathogen is important in the management of candidiasis as the result of differences in susceptibility among species and strains of Candida to different antifungal drugs. Treatment options are reviewed for oropharyngeal candidiasis, vaginal candidiasis, cutaneous candidiasis, paronychia and onychomycosis, and chronic mucocutaneous candidiasis. Because of the importance of predisposing conditions for candidiasis, adjunctive measures to abate these may be useful, although they are seldom effective in immunocompromised patients.

Development of an Animal Model for Neurocysticercosis: Immune Response in the Central Nervous System Is Characterized by a Predominance of γδ T Cells

Neurocysticercosis is the most common parasitic disease of the central nervous system worldwide. It is caused by the metacestode form of the helminth Taenia solium. Study of the immune response in the human brain has been limited by the chronic progression of the disease, the influence of corticosteroid treatment, and the scarcity of patients who undergo surgical intervention. To better understand the immune response and associated pathology in neurocysticercosis, a mouse model was developed by intracranial infection of BALB/c mice with Mesocestoides corti, a cestode organism related to T. solium. The immune response reveals the presence of abundant inflammatory infiltrates appearing as early as 2 days postinfection in extraparenchymal regions. In contrast, infiltration of immune cells into parenchymal tissue is significantly delayed. There is a natural progression of innate (neutrophils and macrophages), early induced (NK cells and γδ T cells), and adaptive immune responses (αβ T cells and B cells) in infected mice. γδ T cells are the predominant T cell population. A cell-mediated Th1 pathway of cytokine expression is evident in contrast to the previously described Th2 phenotype induced in the periphery.

Vaginal candidiasis: review and role of local mucosal immunity

Vulvovaginal candidiasis is a common mucosal fungal infection in women of child-bearing ages. Despite the role for cell-mediated immunity and T cells in host protection against the majority of mucosal Candida albicans infections, there is controversy as to whether immunosuppression by HIV infection enhances susceptibility to vaginal candidiasis. To date, host defense against C. albicans vaginitis has been studied in women with recurrent vaginitis, in HIV-infected women, and in animal models of experimental vaginitis. Together, data suggest that local immunity is more important than that in the systemic circulation for host defense against vaginitis. Thus, current investigations have been focused specifically on innate and acquired immune responses against C. albicans at the vaginal mucosa. This review will discuss the current knowledge of host defenses against C. albicans vaginitis, both systemically and locally, and try to shed some light on several issues surrounding the efficiency of this seemingly compartmentalized immune response.