Validation of a high sensitive immunoenzymatic assay to establish the origin of immunoglobulins in female genital secretions

Cervicovaginal Complement Activation and Microbiota During Pregnancy and in Parturition

Background

Vaginal microbiome and the local innate immune defense, including the complement system, contribute to anti- and proinflammatory homeostasis during pregnancy and parturition. The relationship between commensal vaginal bacteria and complement activation during pregnancy and delivery is not known.

Objective

To study the association of the cervicovaginal microbiota composition to activation and regulation of the complement system during pregnancy and labor.

Study design

We recruited women during late pregnancy (weeks 41 + 5 to 42 + 0, n=48) and women in active labor (weeks 38 + 4 to 42 + 2, n=25). Mucosal swabs were taken from the external cervix and lateral fornix of the vagina. From the same sampling site, microbiota was analyzed with 16S RNA gene amplicon sequencing. A Western blot technique was used to detect complement C3, C4 and factor B activation and presence of complement inhibitors. For semiquantitative analysis, the bands of the electrophoresed proteins in gels were digitized on a flatbed photo scanner and staining intensities were analyzed using ImageJ/Fiji win-64 software. Patient data was collected from medical records and questionnaires.

Results

The vaginal microbiota was Lactobacillus-dominant in most of the samples (n=60), L. iners and L. crispatus being the dominant species. L. gasseri and L. jensenii were found to be more abundant during pregnancy than active labor. L. jensenii abundance correlated with C4 activation during pregnancy but not in labor. Gardnerella vaginalis was associated with C4 activation both during pregnancy and labor. The amount of L. gasseri correlated with factor B activation during pregnancy but not during labor. Atopobium vaginae was more abundant during pregnancy than labor and correlated with C4 activation during labor and with factor B activation during pregnancy. Activation of the alternative pathway factor B was significantly stronger during pregnancy compared to labor. During labor complement activation may be inhibited by the abundant presence of factor H and FHL1.

Conclusions

These results indicate that bacterial composition of the vaginal microbiota could have a role in the local activation and regulation of complement-mediated inflammation during pregnancy. At the time of parturition complement activation appears to be more strictly regulated than during pregnancy.

Activation of the Complement System in the Lower Genital Tract During Pregnancy and Delivery

Background

Human pregnancy alters profoundly the immune system. The local involvement and mechanisms of activation of the complement system in the cervicovaginal milieu during pregnancy and delivery remain unexplored.

Objectives

To determine whether normal pregnancy and delivery are associated with local activation of complement or changes in the immunoglobulin profile in the cervix.

Study Design

This study was designed to assess IgA, IgG, and complement activation in the cervicovaginal area in three groups of patients: i) 49 pregnant women (week 41+3–42+0) not in active labor, ii) 24 women in active labor (38+4–42+2), and iii) a control group of nonpregnant women (n=23) at child-bearing age. We collected mucosal samples from the lateral fornix of the vagina and external cervix during routine visits and delivery. The Western blot technique was used to detect complement C3 and its activation products. For semiquantitative analysis, the bands of the electrophoresed proteins in gels were digitized on a flatbed photo scanner and analyzed. IgA and IgG were analyzed by Western blotting and quantified by ELISA. One-way ANOVA and Tukey’s Multiple Comparison tests were used for statistical comparisons.

Results

A higher abundance but lower activation level of C3 in both the external cervix (P<0.001) and lateral fornix of the vagina (P<0.001) was observed during delivery (58 ± 22, n= 24) in comparison to the groups of nonpregnant (72 ± 13%; mean ± SD, n=23) and pregnant women (78 ± 22%, n=49). Complement activating IgG was detected in higher abundance than IgA in the cervicovaginal secretions of pregnant women. In a small proportion samples also C3-IgG complexes were detected.

Conclusions

Our results reveal an unexpectedly strong activation of the complement system and the presence IgG immunoglobulins in the cervicovaginal area during pregnancy, active labor, and among nonpregnant women. In contrast to the higher amounts of C3 in the cervicovaginal secretions during labor, its activation level was lower. Complement activating IgG was detected in higher concentrations than IgA in the mucosal secretions during pregnancy and labor. Taken together our results imply the presence a locally operating humoral immune system in the cervicovaginal mucosa.

The Multifaceted Nature of Immunoglobulin A and Its Complex Role in HIV

IgA is the most abundant immunoglobulin in mucosal secretions, and understanding the role of IgA in both protection from HIV acquisition and modulation of HIV disease progression is a field of considerable controversy and renewed research interest. Analysis of the RV144 clinical trial associated plasma HIV envelope-specific monomeric IgA from vaccines with reduced vaccine efficacy. The RV144 trial, however, only assessed for plasma IgA, which was not further subclassed, and the role of mucosal IgA was not addressed as mucosal samples were not collected. On the other hand, several studies have detected envelope-specific IgA in mucosal secretions of highly exposed persistently seronegative cohorts, while recent macaque simian-HIV passive immunization studies have suggested a potentially protective role for mucosal IgA. It is well established that total IgA in serum appears to correlate with HIV disease progression. In contrast, a selective deficit of anti-HIV IgA responses in HIV infection is apparent, with a number of recent studies beginning to elucidate the mechanisms behind these dysfunctional IgA responses. In this review, we highlight the dichotomy that exists in the literature as to whether anti-HIV IgA is protective or harmful to the host. Herein, we emphasize the importance of distinguishing between monomeric, multimeric, and isoforms of IgA and review what is known about the complex and diverse interactions of various molecular forms of IgA with HIV in both the systemic circulation and mucosal compartments.

Distinct genital tract HIV-specific antibody profiles associated with tenofovir gel

The impact of topical antiretrovirals for pre-exposure prophylaxis on humoral responses following HIV infection is unknown. Using a binding antibody multiplex assay, we investigated HIV-specific IgG and IgA responses to envelope glycoproteins, p24 Gag and p66, in the genital tract (GT) and plasma following HIV acquisition in women assigned to tenofovir gel (n=24) and placebo gel (n=24) in the CAPRISA 004 microbicide trial to assess if this topical antiretroviral had an impact on mucosal and systemic antibody responses. Linear mixed effect modeling and partial least squares discriminant analysis was used to identify multivariate antibody signatures associated with tenofovir use. There were significantly higher response rates to gp120 Env (P=0.03), p24 (P=0.002), and p66 (P=0.009) in plasma and GT in women assigned to tenofovir than placebo gel at multiple time points post infection. Notably, p66 IgA titers in the GT and plasma were significantly higher in the tenofovir compared with the placebo arm (P<0.05). Plasma titers for 9 of the 10 HIV-IgG specificities predicted GT levels. Taken together, these data suggest that humoral immune responses are increased in blood and GT of individuals who acquire HIV infection in the presence of tenofovir gel.

Broadly neutralizing antibody specificities detected in the genital tract of HIV-1 infected women

BACKGROUND

Broadly neutralizing antibodies (bNAbs) targeting conserved epitopes on the HIV envelope glycoprotein have been identified in blood from HIV-1 infected women. We investigated whether antibodies in the genital tract from these women share similar epitope specificities and functional profiles as those in blood.

METHODS

Immunoglobulin (Ig)G and IgA antibodies were isolated from cervicovaginal lavages or Softcups from 13 HIV-infected women in the CAPRISA cohort using Protein G and Peptide M, respectively. Binding antibodies to envelope antigens were quantified by ELISA and binding antibody multiplex assay. Neutralizing antibody titers and epitope targets were measured using the TZM-bl assay with Env-pseudotyped wild-type and mutated viruses.

RESULTS

HIV-specific IgG, but not IgA, was detected in genital secretions and the ratio of total IgG to HIV-specific IgG was similar to plasma. HIV-specific IgG reacted with multiple envelope antigens, including V1V2, gp120, gp140 and gp41. Two women had high plasma titers of HIV-specific IgG3 which was also detected in their genital tract samples. IgG from the genital tract had neutralizing activity against both Tier 1 and Tier 2 primary HIV-isolates. Antibodies targeting well known glycan epitopes and the membrane proximal region of gp41 were detected in genital secretions, and matched specificities in plasma.

CONCLUSIONS

Women with plasma bNAbs have overlapping specificities in their genital secretions, indicating that these predominantly IgG isotype antibodies may transudate from blood to the genital tract. These data provide evidence that induction of systemic HIV-specific bNAbs can lead to antiviral immunity at the portal of entry.

Differential profiles of immune mediators and in vitro HIV infectivity between endocervical and vaginal secretions from women with Chlamydia trachomatis infection: a pilot study

Chlamydia trachomatis infection is one of the most prevalent bacterial STIs in the USA and worldwide, and women with C. trachomatis infection are at increased risk of acquiring HIV. Because immune activation at the genital mucosa facilitates HIV/SIV infection, C. trachomatis-mediated cytokine induction may contribute to increased HIV transmission in asymptomatic women. To begin to elucidate the mechanisms, we longitudinally analyzed profiles of innate immune factors and HIV infectivity in genital secretions from anatomically specific sites in asymptomatic women during C. trachomatis infection and post-antibiotic treatment. We found higher levels of cytokines and chemokines in endocervical secretions than vaginal secretions. Compared with the convalescent state, G-CSF, IL-1α, and RANTES were elevated in endocervical secretions, IFN-γ and TNF-α were elevated in vaginal secretions, and IFNγ, IL-1β, and MIP1-α were elevated in cervicolavage fluid (CVL), before adjustment of multiple comparisons. Elevated endocervical levels of IP-10 and MCP-1 were associated with the use of hormonal contraception in infected women after successful treatment, suggesting the role of hormonal contraception in inflammation independent of STIs. Importantly, soluble factors found in endocervical secretions during infection enhanced HIV infectivity while no difference in HIV infectivity was found with vaginal secretions or CVL during infection or at convalescence. Taken together, the profiles of immune mediators and in vitro HIV infectivity indicate that the endocervical and vaginal mucosa are immunologically distinct. Our results underscore the importance of considering anatomical site and local sampling methodology when measuring mucosal responses, particularly in the presence of C. trachomatis infection.

Infection of macrophages and dendritic cells with primary R5-tropic human immunodeficiency virus type 1 inhibited by natural polyreactive anti-CCR5 antibodies purified from cervicovaginal secretions

Heterosexual contact is the primary mode of human immunodeficiency virus (HIV) type 1 (HIV-1) transmission worldwide. The chemokine receptor CCR5 is the major coreceptor that is associated with the mucosal transmission of R5-tropic HIV-1 during sexual intercourse. The CCR5 molecule is thus a target for antibody-based therapeutic strategies aimed at blocking HIV-1 entry into cells. We have previously demonstrated that polyreactive natural antibodies (NAbs) from therapeutic preparations of immunoglobulin G and from human breast milk contain NAbs directed against CCR5. Such antibodies inhibit the infection of human macrophages and T lymphocytes by R5-tropic isolates of HIV in vitro. In the present study, we demonstrate that human immunoglobulins from the cervicovaginal secretions of HIV-seronegative or HIV-seropositive women contain NAbs directed against the HIV-1 coreceptor CCR5. Natural affinity-purified anti-CCR5 antibodies bound to CCR5 expressed on macrophages and dendritic cells and further inhibited the infection of macrophages and dendritic cells with primary and laboratory-adapted R5-tropic HIV but not with X4-tropic HIV. Natural anti-CCR5 antibodies moderately inhibited R5-tropic HIV transfer from monocyte-derived dendritic cells to autologous T cells. Our results suggest that mucosal anti-CCR5 antibodies from healthy immunocompetent donors may hamper the penetration of HIV and may be suitable for use in the development of novel passive immunotherapy regimens in specific clinical settings of HIV infection.

Comprehensive Proteomic Analysis of Human Cervical−Vaginal Fluid

Cervical-vaginal fluid (CVF) is a potential rich source of biomarkers for enhancing our understanding of human parturition and pathologic conditions affecting pregnancy. In this study, we performed a comprehensive survey of the CVF proteome in pregnancy utilizing multidimensional liquid chromatography (2D-LC) coupled with mass spectrometry and gel-electrophoresis-based protein separation and identification. In total, 150 unique proteins were identified using multiple protein identification algorithms. Metabolism (32%) and immune response-related (22%) proteins are the major functional categories represented in the CVF proteome. A comparison of the CVF, serum, and amniotic fluid proteomes showed that 77 proteins are unique to CVF, while 56 and 17 CVF proteins also occur in serum and amniotic fluid, respectively. This data set provides a foundation for evaluation of these proteins as potential CVF biomarkers for noninvasive diagnosis of pregnancy-related disorders.

Contraceptive responses of female hamsters immunized with recombinant sperm protein P26h

BACKGROUND

A number of antigens have been characterized and proposed as potential candidates for immunocontraception. P26h, a 26-kDa hamster sperm protein located on the acrosomal cap, is known to be involved in sperm-zona pellucida interactions. Furthermore, in vivo fertilization can be blocked by active immunization of male hamsters against P26h or maltose-binding protein recombinant P26h (MBP-P26h).

OBJECTIVE

The aim of this study was to investigate the immune response and reproductive function of female hamsters immunized against MBP-P26h.

RESULTS

Active immunization against MBP-P26h resulted in anti-P26h circulating antibodies, with enzyme-linked immunosorbent assay (ELISA) titers showing interindividual variability. The antibodies produced by the animals immunized against MBP-P26h reacted with the native P26h protein in ELISA, in Western blot analysis and in immunostaining performed on cauda epididymal spermatozoa. Mating of immunized female hamsters resulted in a significant decrease in the number of viable fetuses only in females with high titers of anti-P26h circulating antibodies.

DISCUSSION

This result is in agreement with the sperm-zona pellucida binding assay's results. Indeed, sera collected from immunized animals, and not from control animals, significantly blocked sperm-zona pellucida binding in vitro. Histological studies showed that active immunization did not cause any pathology in the reproductive tissues.

CONCLUSION

These findings suggest that P26h is a potential candidate for the development of a contraceptive vaccine in both males and females.

Effects of a short-course of amoxicillin/clavulanic acid on systemic and mucosal immunity in healthy adult humans

Although amoxicillin/clavulanic acid (AMC) is the most frequently administered antibiotic in France, its in vivo effects on immunity in healthy adults have never, to our knowledge, been described. Eighteen healthy adult male volunteers, 25+/-6 years old, were treated for 5 days with oral amoxicillin (1 g) /clavulanate potassium (125 mg), two times daily. Systemic and local intestinal immunity parameters were sequentially explored before, during and after the antibiotic treatment. No significant differences were obtained for transudation markers (albumin and alpha1-antitrypsin) in sera, feces and saliva, showing that AMC did not induce inflammatory reaction. Phagocytosis, peripheral blood cell subsets, intracellular interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha production by natural killer (NK) cells and cytotoxic T lymphocytes, intracellular TNF-alpha production by monocytes showed no significant differences throughout the trial. In fecal outputs, no significant differences were found in secretory immunoglobulin A (S-IgA), lactoferrin (Lf), lysozyme (Lz) and transforming growth factor (TGF)-beta1. In sera, concentrations of total IgA (T-IgA), S-IgA, IgM, Lf and Lz did not show any significant variations throughout the study, whereas concentrations of IgG were slightly but significantly reduced 15 days after AMC treatment. In saliva, concentrations of T-IgA were slightly but significantly higher, whereas S-IgA concentrations were unchanged. Our results showed that oral AMC intake did not induce any significant adverse effects on immunity in adult humans.

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.

High-Risk Papillomavirus Infection Is Associated with Altered Antibody Responses in Genital Tract: Non-specific Responses in HPV Infection

In order to gain more information about local humoral immune responses to HPV infection, we quantified IgG, IgM, secretory-IgA (S-IgA), and total-IgA by ELISA, and lysozyme and lactoferrin by TR-IFMA, in cervical and cervicovaginal secretions of 40 healthy women and 28 high-risk HPV infected patients (11 were HPV16+). IgG, total-IgA, and S-IgA concentrations in cervicovaginal secretions (p < 0.0001) and high IgG and total-IgA concentrations (p < 0.001 and p < 0.01, respectively) in endocervical secretions were significantly higher in HPV+ patients than in the healthy group. Since the S-IgA/total-IgA ratio was significantly lower in cervicovaginal (7.5%) and endocervical secretions (36.5%) in HPV+ women compared to the control group (p < 0.003 and p < 0.001, respectively), HPV could be responsible for an increase in local production of non-secretory IgA (monomeric and dimeric forms). IgG and total-IgA concentrations in cervicovaginal and endocervical secretions fell in the same general percentage range in both HPV16+ and HPV+ groups (80% and 15%, respectively). However, the S-IgA/total-IgA ratio was much lower in HPV16+ than in HPV+ women, in both cervicovaginal secretions (3.4%) (p < 0.003) and in endocervical secretions (23.3%) (p < 0.001). Innate immunity proteins and local S-IgA response could not stop the spread of HPV infection in spite of high lysozyme and lactoferrin concentrations. HPV16+ disturbed the local humoral immune system, which could partly explain its low clearance.

Paucity of antigen-specific IgA responses in sera and external secretions of HIV-type 1-infected individuals

This study was undertaken to resolve existing controversies with respect to the detection of IgA HIV-1-specific mucosal antibodies in infected individuals. External secretions, including tears, nasal, rectal, and vaginal washes, saliva, semen, urine, and sera were obtained from 50 HIV-1-infected individuals and 20 controls using collection procedures that minimize the irritation of mucosal surfaces. Levels of total and antigen (gp120 and gp160)-specific antibodies of the IgG and IgA isotypes were measured by assays that proved reliable in a large multicenter study: quantitative ELISA and chemiluminescence-enhanced Western blot analyses. Although the levels of total IgG and IgA were increased or remained unchanged in body fluids of HIV-1-infected individuals as compared to the controls, HIV-1-specific IgA antibodies were either absent or present at low levels even in secretions with characteristically high relative contents of total IgA vs. IgG (saliva, tears, and rectal and nasal washes). In these secretions, HIV-1-specific IgG antibodies dominated. In assessing levels and frequency of detection of IgG antibodies, both female and male genital tract secretions, urine, and nasal wash were preferable to parotid saliva and especially to rectal wash. External secretions contained IgG antibodies to gp160> gp120> gp41 and p24; when present, IgA antibodies were predominantly directed at gp160. Analyses of peripheral blood antibody-secreting cells (ASC) isolated from the same individuals paralleled these serological findings: gp160-specific IgG-secreting ASC were dominant. Therefore, in striking contrast to other mucosally encountered microbial infections, HIV-1 does not induce vigorous specific IgA responses in any body fluid examined or in ASC in peripheral blood.

New sensitive method for the measurement of lysozyme and lactoferrin for the assessment of innate mucosal immunity. part I: time-resolved immunofluorometric assay in serum and mucosal secretions

Mucous peristalsis, mucus and immunity proteins, such as lysozyme and lactoferrin, are part of humoral innate immunity. The aim of this study was to develop a quantitative method, a time-resolved-immunofluorometric assay, to measure lysozyme and lactoferrin in sera, saliva, stools and cervico-vaginal secretions. This method was validated in 51 healthy subjects. Linearity for lysozyme was between 1.02 and 25 microg/l and for lactoferrin between 1.02 and 100 microg/l. The detection limit was 0.5 microg/l for lysozyme and 1 microg/l for lactoferrin. Albumin and alpha1-antitrypsin were measured by immuno-nephelometry to calculate salivary, intestinal and cervico-vaginal coefficients of excretion. Lysozyme and lactoferrin were present in all types of mucosal surfaces. Very high concentrations of lysozyme and lactoferrin were found in cervico-vaginal fluid (166.2 and 72.7 mg/l, respectively), compared to the concentrations found in the other mucosal fluids. Lysozyme in stools was produced at the rate of 0.42 mg/d compared to 0.02 mg/d lactoferrin production. Lysozyme and lactoferrin greatly exceeded the values expected from the molecular weight-affected seepage from plasma, suggesting primarily local synthesis in healthy subjects. Quantitative measurement of lysozyme and lactoferrin can aid in the assessment of the activity of mucus-associated lymphoid tissues in innate immunity, and can help in further understanding of the role of these proteins in mucosal diseases.

Nonspecific secretory immunity in HIV-infected patients with oral candidiasis

Buccal and digestive tract opportunistic infections occur frequently in patients infected by HIV. In this study, we measured lysozyme (Lz), lactoferrin (Lf), total IgA (T-IgA), and secretory IgA (S-IgA) levels to investigate nonspecific secretory immunity in HIV-infected patients with oral candidiasis. Serum, saliva, and stool samples were analyzed by time-resolved immunofluorometric assay for Lz and Lf levels and by enzyme-linked immunosorbent assay for T-IgA and S-IgA levels. Mean salivary Lf and T-IgA levels (66.50 mg/L and 0.10 g/L, respectively) and mean fecal Lf, T-IgA, and S-IgA outputs (0.87, 54.0, and 43.6 mg/d, respectively) were significantly higher in HIV-infected patients with oropharyngeal candidiasis than in HIV-infected patients without oropharyngeal candidiasis and healthy subjects. There was a modification in the molecular form rate, with a high increase in S-IgA and monomeric IgA transudation from the plasmatic compartment into salivary and digestive fluids and an increase in salivary Lf local synthesis by polymorphonuclear neutrophils. HIV infection appears to be associated with dysregulation of some of the nonspecific immune factors at the mucosal surface. Despite high saliva concentrations and high intestinal output, innate immunity was not able to stop yeast expansion in HIV-infected patients.