Immunity in the female lower genital tract and the impact of HIV infection

Infiltrating T-cell markers in cervical carcinogenesis: a systematic review and meta-analysis

BACKGROUND

The host adaptive immune response helps determine which cervical HPV infections persist and progress to precancer and cancer, and systematic characterisation of T-cell infiltration would help inform key steps in cervical carcinogenesis.

METHODS

A systematic review and meta-analysis were conducted of infiltrating T-cells in normal cervix, low-grade lesions, high-grade lesions, and invasive cancers including epithelial, stromal, and total tissue and the following markers: CD3, CD4, CD8, FoxP3, CD25, and the CD4:CD8 ratio. An additional qualitative review summarised longitudinal data on associations between infiltrating T-cells and cervical disease persistence, regression, progression, or prognosis.

RESULTS

There were fewer CD3+, CD4+, and CD8+ cells in cervical lesions and more cells in cancers compared to normal epithelium. FoxP3 and CD25+ regulatory T-cell infiltration is high in persistent and precancerous lesions, and longitudinal data show improved outcomes with lower regulatory T-cell levels.

CONCLUSIONS

Successful immune evasion may reduce T-cell infiltration in HPV infected and precancerous epithelium, while invasive cancers are highly immunogenic, and regulatory T-cell infiltration increases with cervical disease progression. Understanding these factors may have prognostic value and could aid in novel treatment development and clinical guidelines, but published data are highly heterogeneous and leave important gaps to be filled by future studies.

Comparison of Mucosal Markers of Human Immunodeficiency Virus Susceptibility in Healthy Premenopausal Versus Postmenopausal Women

The objective of this study was to characterize cervicovaginal (CV) mucosal factors modulating susceptibility to human immunodeficiency virus (HIV) acquisition in healthy premenopausal (PRE) and postmenopausal (POST) women before and after treatment with estradiol (E2). We compared CV mucosal epithelial histology and immune cells, vaginal microbiota, antimicrobial activity of and soluble mucosal protein concentrations in the CV fluid lavage (CVL), and p24 antigen production after ex vivo infection of ectocervical tissues with HIV-1_BaL among PRE women (n = 20) in the follicular and luteal phases of the menstrual cycle and POST women (n = 17) at baseline and after ∼1 month of treatment with 0.01% vaginal E2 cream. Compared to PRE women, we measured higher levels of p24 antigen after ex vivo infection in tissues from POST women. POST women had a significantly thinner vaginal epithelium with decreased tight junction proteins and a higher density of mucosal immune T cells and lower levels of CD1a antigen-presenting cells, antimicrobial peptides, and inflammatory cytokines in the CVL (p values <.05). POST women had higher vaginal pH and lower vaginal Lactobacilli (p values <.05) than PRE women. After vaginal E2 therapy, CV endpoints and ex vivo HIV replication in POST tissues were similar to those observed in PRE tissues. The CV mucosa in POST women is thinned and compromised, with increased HIV-target immune cells and decreased antimicrobial factors, being more susceptible to HIV infection. After POST women receive topical E2 treatment, mucosal endpoints are similar to PRE levels.

A randomized clinical trial on the effects of progestin contraception in the genital tract of HIV-infected and uninfected women in Lilongwe, Malawi: Addressing evolving research priorities

Hormonal contraception is central in the prevention of unintended pregnancy; however there are concerns that certain methods may increase the risk of HIV acquisition and transmission. Hormonal contraceptives may modify the genital mucosa in several ways, however the mechanisms are incompletely understood. Few studies have examined genital HIV shedding prospectively before and after initiation of hormonal contraception. The effects of hormonal contraception on genital HIV shedding in the setting of antiretroviral therapy (ART) are also unknown. We designed a pilot clinical trial in which HIV-infected and uninfected women were randomized to either depot medroxyprogesterone acetate (DMPA) injectable or levonorgestrel (LNG) implant in Lilongwe, Malawi. The objectives were to: 1) assess the effect and compare the impact of type of progestin contraception (injectable versus implant) on HIV genital shedding among HIV-infected women, 2) assess the effect and compare the impact of type of progestin contraception on inflammatory/immune markers in the genital tract of both HIV-infected and uninfected women, and 3) assess the interaction of progestin contraception and ART by examining contraceptive efficacy and ART efficacy. An additional study aim was to determine the feasibility and need for a larger study of determinants of HIV transmissibility and acquisition. As injectable contraception is widely used in many parts of the world with high HIV prevalence, this study will provide important information in determining the need for and feasibility of a larger study to address these questions that can impact the lives of millions of women living with or at risk for HIV.

Mucosal and Systemic γδ+ T Cells Associated with Control of Simian Immunodeficiency Virus Infection

γδ T cells act as a first line of defense against invading pathogens. However, despite their abundance in mucosal tissue, little information is available about their functionality in this compartment in the context of HIV/SIV infection. In this study, we evaluated the frequency, phenotype, and functionality of Vδ1 and Vδ2 T cells from blood, rectum, and the female reproductive tract (FRT) of rhesus macaques to determine whether these cells contribute to control of SIV infection. No alteration in the peripheral Vδ1/Vδ2 ratio in SIV-infected macaques was observed. However, CD8⁺ and CD4⁺CD8⁺ Vδ1 T cells were expanded along with upregulation of NKG2D, CD107, and granzyme B, suggesting cytotoxic function. In contrast, Vδ2 T cells showed a reduced ability to produce the inflammatory cytokine IFN-γ. In the FRT of SIV⁺ macaques, Vδ1 and Vδ2 showed comparable levels across vaginal, ectocervical, and endocervical tissues; however, endocervical Vδ2 T cells showed higher inflammatory profiles than the two other regions. No sex difference was seen in the rectal Vδ1/Vδ2 ratio. Several peripheral Vδ1 and/or Vδ2 T cell subpopulations expressing IFN-γ and/or NKG2D were positively correlated with decreased plasma viremia. Notably, Vδ2 CD8⁺ T cells of the endocervix were negatively correlated with chronic viremia. Overall, our results suggest that a robust Vδ1 and Vδ2 T cell response in blood and the FRT of SIV-infected macaques contribute to control of viremia.

Evaluation of T, B and natural killer lymphocyte in the cervical stroma of HIV-positive and negative patients with cervical intraepithelial neoplasia

Cervical intraepithelial neoplasias (CIN) are closely associated with oncogenic subtypes of the human papillomavirus (HPV). In the presence of this virus, it is known that the activation or suppression of immune system is the key to the development, progression and/or regression of cervical lesions. Therefore, the objective of this study is to compare the local immune response among HIV-seropositive and seronegative patients with cervical intraepithelial neoplasia regarding the expression of T lymphocytes (CD3+, CD4+ and CD8+), B lymphocytes (CD20+) and natural killers cells (CD56+) in the cervical stroma. A cross-sectional study of paraffin blocks containing cervical tissue after conization by the Loop Electrosurgical Excision Procedure (LEEP) from 47 HIV-seropositive and 38 seronegative patients with CIN. Cervical stroma immunohistochemistry was performed in the CIN area. The Fisher's exact test was used for the statistical analysis. When HIV-seropositive and seronegative women were compared, the seropositive women had a higher count of CD8+ T lymphocytes (52.1% versus 28.9%, P<0.04). Considering CIN degree (CIN 1 and CIN 2/3), the HIV-seronegative patients with CIN 1 had a low count of CD20+B-lymphocytes (7.1%) in comparison with CIN 1 HIV seropositive and with CIN 2/3 HIV-seronegative patients, respectively 50% (P<0.018) and 54.5% (P<0.0048). The HIV infection and degree of CIN influenced the cytotoxic lymphocytes inducing an increase in the number of cells high count of CD20+ lymphocytes with CIN 1.

Relationship Between Genital Drug Concentrations and Cervical Cellular Immune Activation and Reconstitution in HIV-1-Infected Women on a Raltegravir Versus a Boosted Atazanavir Regimen

Determinants of HIV-infected women's genital tract mucosal immune health are not well understood. Because raltegravir (RAL) achieves relatively higher genital tract concentrations than ritonavir-boosted atazanavir (ATV), we examined whether an RAL-based regimen is associated with improved cervical immune reconstitution and less activation in HIV(+) women compared to an ATV-based regimen. Peripheral blood, cervical brushings, cervical-vaginal lavage (CVL), and cervical biopsies were collected from HIV(+) women on tenofovir disoproxil fumarate and emtricitabine (TDF/FTC) and either RAL (n=14) or ATV (n=19) with CD4(+) T cells>300 cells/mm(3) and HIV RNA<48 copies/ml. HLA-DR(+)CD38(+) T cells were measured in blood and cervical cells using flow cytometry, CD4(+) and CD8(+) T cells were quantified in cervical biopsies by immunofluorescent analysis, and HIV RNA (VL), ATV, and RAL concentrations were measured in CVL. In a linear regression model of log(CVL concentration) versus both log(plasma concentration) and treatment group, the RAL CVL level was 519% (95% CI: 133, 1,525%) higher than for ATV (p<0.001). Genital tract VL was undetectable in 90% of subjects and did not differ by regimen. There were no significant differences between groups in terms of cervical %HLA-DR(+)CD38(+)CD4(+) or CD8(+) T cells, CD4(+) or CD8(+) T cells/mm(2), or CD4:CD8 ratio. After adjusting for treatment time and group, the CVL:plasma drug ratio was not associated with the cervical CD4:CD8 ratio or immune activation (p>0.6). Despite significantly higher genital tract penetration of RAL compared to ATV, there were no significant differences in cervical immune activation or reconstitution between women on these regimens, suggesting both drug regimens achieve adequate genital tract levels to suppress virus replication.

Depot medroxyprogesterone acetate increases immune cell numbers and activation markers in human vaginal mucosal tissues

The relationship between exogenous contraceptive hormones and permissiveness of the female genital tract to human immunodeficiency virus type 1 (HIV-1) is the subject of renewed debate. To better characterize the effect of depot medroxyprogesterone acetate (DMPA) on HIV-1 cellular targets and epithelial integrity in the vagina, we compared leukocyte populations, markers of activation and proliferation, and the density of intercellular junctional proteins in the vaginal epithelium of women during the follicular and luteal phases of the menstrual cycle and approximately 12 weeks after receiving a DMPA injection. This prospective cohort study involved 15 healthy women. Vaginal biopsies were obtained in the follicular and luteal phases of the menstrual cycle, and approximately 12 weeks following a 150-mg intramuscular injection of DMPA. Leukocyte populations, activation phenotype, and epithelial tight junction and adherens proteins were evaluated by immunohistochemistry. After receiving DMPA, the numbers of CD45, CD3, CD8, CD68, HLA-DR, and CCR5 bearing immune cells were significantly (p<0.05) increased in vaginal tissues, compared to the follicular and/or luteal phases of untreated cycles. There were no significant differences in immune cell populations between the follicular and luteal phases of the control cycle. There were also no statistically significant differences in epithelial thickness and density of epithelial tight junction and adherens proteins among the follicular, luteal, and post-DMPA treatment sampling points. In this pilot study, vaginal immune cell populations were significantly altered by exogenous progesterone, resulting in increased numbers of T cells, macrophages, and HLA-DR- and CCR5-positive cells.

Dendritic cells and macrophages in the genitourinary tract

Dendritic cells (DCs) and macrophages are antigen-presenting cells (APCs) that are important in innate immune defense as well as in the generation and regulation of adaptive immunity against a wide array of pathogens. The genitourinary (GU) tract, which serves an important reproductive function, is constantly exposed to numerous agents of sexually transmitted infections (STIs). To combat these STIs, several subsets of DCs and macrophages are strategically localized within the GU tract. In the female genital mucosa, recruitment and function of these APCs are uniquely governed by sex hormones. This review summarizes the latest advances in our understanding of DCs and macrophages in the GU tract with respect to their subsets, lineage, and function. In addition, we discuss the divergent roles of these cells in immune defense against STIs as well as in maternal tolerance to the fetus.

TLR2-mediated cell stimulation in bacterial vaginosis

Bacterial vaginosis (BV) is associated with preterm labor, pelvic inflammatory disease (PID) and increased HIV acquisition, although the pathways that mediate these pathological effects have not been elucidated. To determine the presence of Toll-like receptor (TLR)-ligands and their specificity in BV, genital tract fluids were collected from women with and without BV by cervicovaginal lavage (CVL). The CVL samples were evaluated for their ability to stimulate secretion of proinflammatory cytokines and to activate NFkappaB and the HIV long terminal repeat (LTR), indicators of TLR activation, in human monocytic cells. Stimulation with BV CVLs induced higher levels of IL-8 and TNFalpha secretion, as well as higher levels of HIV LTR and NFkappaB activation, than CVLs from women with normal healthy bacterial flora. To identify which TLRs were important in BV, 293 cells expressing specific TLRs were exposed to CVL samples. BV CVLs induced higher IL-8 secretion by cells expressing TLR2 than CVLs from women without BV. Surprisingly, BV CVLs did not stimulate cells expressing TLR4/MD2, although these cells responded to purified lipopolysaccharide (LPS), a TLR4 ligand. BV CVLs, in cells expressing TLR2, also activated the HIV LTR. Thus, these studies show that soluble factor(s) present in the lower genital tract of women with BV activate cells via TLR2, identifying a pathway through which BV may mediate adverse effects.

T-Lymphocyte Profile and Total and Virus-Specific Immunoglobulin Concentrations in the Cervix of HIV-1-Infected Women

BACKGROUND

The mucosal lymphocyte population is the largest in the body, and the gastrointestinal compartment has been well characterized in HIV infection. Much less is known about the effects of HIV on the genital tract.

OBJECTIVE

: To examine the T-lymphocyte phenotype and receptor repertoire as well as total and virus-specific immunoglobulin concentrations in the endocervix of HIV-infected women at different stages of infection as compared with uninfected women.

PATIENTS AND METHODS

Participants were 12 seronegative women, 10 HIV-infected "slow progressors" not taking antiretroviral therapy, and 9 HIV-infected women whose antiretroviral therapy was failing. We used multiparameter flow cytometry to enumerate T-cell populations on cytobrush-obtained cervical specimens, the immunoscope technique to determine the T-cell receptor (TCR) repertoire, and quantitative enzyme-linked immunosorbent assays for antibody determinations on cervical secretions absorbed onto ophthalmic sponges. Nonparametric statistical analyses were performed.

RESULTS

We found marked depletion of leukocytes and CD4 T lymphocytes in the endocervix of HIV-infected women as compared with uninfected women; this was significant at more advanced disease stages. Naive T cells were rare in the endocervix of all groups. Activation marker expression was higher in endocervical T lymphocytes than in peripheral blood among control and slow-progressing HIV-infected women but not in women failing therapy. Endocervical T lymphocytes showed highly restricted utilization of Vbeta TCR families. Unlike other mucosal sites, the cervix contained IgG as the predominant immunoglobulin isotype. HIV-IgG was detected in the cervix of most HIV-infected women and in blood of all infected women.

CONCLUSIONS

HIV infection induces substantial changes in the immune profile of the female genital tract. Further study of the implications of these findings for HIV acquisition and transmission is needed.

Langerhans' cell count and HLA class II profile in cervical intraepithelial neoplasia in the presence or absence of HIV infection

OBJECTIVES

The progression of immunosuppression in human immunodeficiency virus (HIV)+ women has been correlated with elevated incidence of squamous intraepithelial lesions (SIL), probably indicating the role of local immune milieu. In this study, we analysed S100, and HLA class II molecule expression in cervical biopsies according to HIV status, to the severity of SIL and to human papillomavirus (HPV) type.

METHODS

Biopsies from 34 HIV+ and 44 HIV- patients with normal cervix or low- or high-grade SIL were studied. Langerhans' cells (LC) (S100), HLA class II and HLA-DQ molecules were evaluated by immunohistochemistry. HPV detection was performed using polymerase chain reaction (PCR). For statistical analysis Mann-Whitney (P< or =0.05) and Spearman test were used.

RESULTS

Epithelial S100 and HLA class II density were significantly increased with the severity of lesion (P=0.032; P=0.005). Epithelial S100+ increased in HPV+ (P=0.038), and HLA class II density decreased in HPV 16+ (P=0.035) or 18+ (P<0.0001) samples. HIV infection was associated with increased stromal S100+ (P=0.0005) and decreased HLA class II densities (P=0.0001). Decreased stromal S100+ was observed in women with CD4<500 cells/microl (P=0.050). Among HIV+ patients with SIL, the lowest S100 and epithelial HLA class II densities were detected in women with CD4<200 cells/microl (P=0.045).

CONCLUSIONS

After the establishment of AIDS, increased numbers of immature LCs and a reduction in HLA class II occurred, possibly turning the cervical milieu more favourable to HPV persistence. HPV 16 and 18 infections may interfere with the antigen presenting activity, possibly as an evasion mechanism.

Immunology of the human genital tract

PURPOSE OF REVIEW

Despite much interest in the mechanisms of immune protection against sexually transmitted diseases (STDs), little is known about the role of the immune system in the genital tract. A better knowledge is needed to understand not only host protection against STDs, but also how tolerance is established in pregnancy to avoid rejection of the foetus.

RECENT FINDINGS

The immune system of the genital tract displays characteristic features that are unique, and therefore distinct from those of other mucosal and systemic immune sites. It is functionally separate from the mucosal immune systems of the lung or intestine, and contrary to these systems, antibodies in the genital tract are dominated by IgG and not IgA. Most of the IgA is polymeric and consists of equal proportions IgA1 and IgA2. Polymeric IgA is actively transported via the polymeric immunoglobulin receptor on the basolateral surface of the epithelial cell, whereas it is not known how IgG antibodies are secreted. Antibody levels and isotypes exhibit strong hormonal dependence. Less is known about cell-mediated immune responses in the genital tract. Interest has focused on adhesion molecules, the existence of regulatory T and natural killer cells, and whether innate and early adaptive immune responses may be stimulated by local vaginal, intranasal or intestinal vaccinations. These topics are reviewed here and the most recent developments in these areas are reported.

SUMMARY

A greater knowledge of immune activation and the homing of leukocytes to the genital tract is important for future attempts to design vaccines against STDs, as well as in understanding foetal tolerance.

Calcium phosphate nanoparticles induce mucosal immunity and protection against herpes simplex virus type 2

Previously we reported that calcium phosphate nanoparticles (CAP) represented a superior alternative to alum adjuvants in mice immunized with viral protein. Additionally, we showed that CAP was safe and elicited no detectable immunoglobulin E (IgE) response. In this study, we demonstrated that following mucosal delivery of herpes simplex virus type 2 (HSV-2) antigen with CAP, CAP adjuvant enhanced protective systemic and mucosal immunity versus live virus. Mice were immunized intravaginally and intranasally with HSV-2 protein plus CAP adjuvant (HSV-2+CAP), CAP alone, phosphate-buffered saline, or HSV-2 alone. HSV-2+CAP induced HSV-specific mucosal IgA and IgG and concurrently enhanced systemic IgG responses. Our results demonstrate the potency of CAP as a mucosal adjuvant. Furthermore, we show that systemic immunity could be induced via the mucosal route following inoculation with CAP-based vaccine. Moreover, neutralizing antibodies were found in the sera of mice immunized intranasally or intravaginally with HSV-2+CAP. Also, the results of our in vivo experiments indicated that mice vaccinated with HSV-2+CAP were protected against live HSV-2 infection. In conclusion, these preclinical data support the hypothesis that CAP may be an effective mucosal adjuvant that protects against viral infection.

The cellular response associated with cervical intraepithelial neoplasia in HIV+ and HIV- subjects

This study investigates local alterations in T-cell and macrophage subsets that occur in cervical epithelial neoplasia (CIN), in the presence and absence of human immunodeficiency virus (HIV) infection. Ectocervical biopsies from 10 women with CIN who were infected with HIV, and 10 women with CIN but no HIV infection were studied by immunocytochemistry. Significantly increased proportions of activated CD8+ T cells were seen in all CIN biopsies, and these proportions were further increased in the presence of HIV infection. Levels of CD8+TIA-1+ cells were particularly increased in the CIN+HIV+ group. There was a lack of expression of CD28 on the CD8+ cells of the epithelium of CIN+HIV+ samples. A significant reduction in the proportion of epithelial inductive D1+ macrophages and an increase in D1+D7+-suppressive cells were observed in the CIN+HIV+ cohort. The lack of expression of CD28 on the CD8+ cells of the epithelium of CIN+HIV+ samples in combination with the reduced CD4+ T-cell numbers seen in the presence of HIV infection may contribute to the development of higher grade CIN in this susceptible group. This may be aggravated by the reduction in the D1+ epithelial inductive macrophages, which might reflect recruitment of more suppressive D1+D7+ cells. This would further compromise the ability of the local T-cell system to respond to antigens and thus contribute to the development of neoplasia at this site. These results suggest that the increase in activated CD8+ T cells is a consequence rather than a cause of CIN.

Interactions of the female hormonal environment, susceptibility to viral infections, and disease progression

Sex hormones influence susceptibility and disease predisposition for many genital tract infections. This review describes the mechanisms by which sex steroids affect mucosal immunity, with particular reference to human immunodeficiency virus (HIV) and genital herpes, and the stage-specific effects of hormonal contraception on human papillomavirus (HPV) infection. Estrogen's role is important in the early stages of several infections as it stimulates antibody- and cell-mediated immune responses. There is increased expression of some cytokines in peripheral blood and vaginal fluids during the follicular phase of the menstrual cycle and with use of hormonal contraception. Whether estrogen exerts a protective or deleterious influence depends on the infecting organism and stage of infection or disease. Estrogen apparently reduces susceptibility to primary HPV infection but in the event of persistent HPV infection, sex steroid hormones (estrogen and/or progesterone) are associated with progression to cervical cancer. It is important that these stage-specific effects are better described because most vaccines will try to prevent either infection or disease. Clinicians with patients at high risk of sexually transmitted infections, especially HIV, require better information on the risks associated with different hormonal contraceptive regimes.