Identification of biomarkers to measure HIV-specific mucosal and systemic CD8(+) T-cell immunity using single cell Fluidigm 48.48 Dynamic arrays

Thirty genes composed of cytokines, chemokines, granzymes, perforin and integrins were evaluated in gut and splenic K(d)Gag197-205-specific single CD8(+) T cells using Fluidigm 48.48 Dynamic arrays, with the aim of identifying biomarkers to predict effective mucosal and systemic vaccine efficacy. The mRNA expression profiles were analyzed in three ways: (i) the "number" of K(d)Gag197-205-specific CD8(+) T cells expressing the biomarker, (ii) "level" of mRNA expression using principal component analysis (PCA) and (iii) poly-functionality in relation to RANTES expression. In total, 21 genes were found to be differentially expressed between the vaccine groups and the immune compartments tested. Overall, the PCA indicated that IL-13Rα2 or IL-4R antagonist adjuvanted vaccines that previously induced high-avidity mucosal/systemic CD8(+) T cells with better protective efficacy, the "level" of mRNA expression, specifically RANTES, MIP-1β, and integrin α4 in gut K(d)Gag197-205-specific single CD8(+) T cells, were significantly elevated compared to unadjuvanted vaccine. Furthermore, significantly elevated granzymes/perforin levels were detected in IL-13(-/-) mice given the unadjuvanted vaccine, indicating that the degree of IL-13 inhibition (total, transient or no inhibition) can considerably alter the level of T-cell activity/poly-functionality. When splenic- and gut-K(d)Gag197-205-specific CD8(+) T cells were compared, PC1 vs. PC2 scores revealed that not only RANTES, MIP-1β, and integrin α4 mRNA, but also perforin, granzymes A/B, and integrins β1 and β2 mRNA were elevated in spleen. Collectively, data suggest that RANTES, MIP-1β, perforin, and integrins α4, β1 and β7 mRNA in single HIV-specific CD8(+) T cells could be used as a measure of effective mucosal and systemic vaccine efficacy.

Characterization of the Genital Microenvironment of Female Rhesus Macaques Prior to and After SIV Infection

PROBLEM

HIV infection among women is frequently modeled in female rhesus macaques. Longitudinal studies on genital compartment and hormonal factors that can influence susceptibility to SIV infection are lacking in this animal model.

METHOD OF STUDY

Genital specimens and menstruation of indoor-housed female rhesus macaques were analyzed prior to and after SIV infection.

RESULTS

Median menstrual cycle length averaged 27 days, although highly variable cycle lengths and frequent periods of amenorrhea were observed during summer months. The vaginal microbiota, characterized by adapted Nugent scoring, showed predominance of small Gram-variable rods and Gram-positive cocci. Highly variable vaginal cytokine levels were observed pre- and post-SIV infection. Vaginal viral loads correlated with plasma viral loads, but were not associated with progesterone levels.

CONCLUSION

These results provide an integrated characterization of important factors in the vaginal microenvironment that are relevant to the experimental design of HIV prevention and transmission studies in female rhesus macaques.

Randomized Cross-Sectional Study to Compare HIV-1 Specific Antibody and Cytokine Concentrations in Female Genital Secretions Obtained by Menstrual Cup and Cervicovaginal Lavage

Introduction

Optimizing methods for genital specimen collection to accurately characterize mucosal immune responses is a priority for the HIV prevention field. The menstrual cup (MC) has been proposed as an alternative to other methods including cervicovaginal lavage (CVL), but no study has yet formally compared these two methods.

Methods

Forty HIV-infected, antiretroviral therapy-naïve women from the CAPRISA 002 acute HIV infection cohort study were randomized to have genital fluid collected using the MC with subsequent CVL, or by CVL alone. Qualitative data, which assessed levels of comfort and acceptability of MC using a 5-point Likert scale, was collected. Luminex multiplex assays were used to measure HIV-specific IgG against multiple gene products and 48 cytokines.

Results

The majority (94%) of participants indicated that insertion, wearing and removal of the MC was comfortable. Nineteen MCs with 18 matching, subsequent CVLs and 20 randomized CVLs were available for analysis. Mucosal IgG responses against four HIV-antigens were detected in 99% of MCs compared to only 80% of randomized CVLs (p = 0.029). Higher specific antibody activity and total antibodies were observed in MCs compared to CVL (all p<0.001). In MCs, 42/48 (88%) cytokines were in the detectable range in all participants compared to 27/48 (54%) in CVL (p<0.001). Concentrations of 22/41 cytokines (53.7%) were significantly higher in fluid collected by MC. Both total IgG (r = 0.63; p = 0.005) and cytokine concentrations (r = 0.90; p<0.001) correlated strongly between MC and corresponding post-MC CVL.

Conclusions

MC sampling improves the detection of mucosal cytokines and antibodies, particularly those present at low concentrations. MC may therefore represent an ideal tool to assess immunological parameters in genital secretions, without interfering with concurrent collection of conventional CVL samples.

The Influence of Immunization Route, Tissue Microenvironment, and Cytokine Cell Milieu on HIV-Specific CD8+ T Cells Measured Using Fluidigm Dynamic Arrays

Thirty different genes including cytokines, chemokines, granzymes, perforin and specifically integrins were evaluated in Peyer's patch-KdGag_197–205-specific CD8+ T cells (pools of 100 cells) using Fluidigm 48.48 Dynamic arrays following three different prime-boost immunization strategies. Data revealed that the route of prime or the booster immunization differentially influenced the integrin expression profile on gut KdGag_197–205-specific CD8+ T cells. Specifically, elevated numbers of integrin αE and αD expressing gut KdGag_197–205-specific CD8+ T cells were detected following mucosal but not systemic priming. Also, αE/β7 and αD/β2 heterodimerization were more noticeable in an intranasal (i.n.)/i.n. vaccination setting compared to i.n./intramuscular (i.m) or i.m./i.m. vaccinations. Moreover, in all vaccine groups tested α4 appeared to heterodimerize more closely with β7 then β1. Also MIP-1β, RANTES, CCR5, perforin and integrin α4 bio-markers were significantly elevated in i.n./i.m. and i.m./i.m. immunization groups compared to purely mucosal i.n./i.n. delivery. Furthermore, when wild type (WT) BALB/c and IL-13 knockout (KO) mice were immunized using i.n./i.m. strategy, MIP-1α, MIP-1β, RANTES, integrins α4, β1 and β7 mRNA expression levels were found to be significantly different, in mucosal verses systemic KdGag_197–205-specific CD8+ T cells. Interestingly, the numbers of gut KdGag_197–205-specific CD8+ T cells expressing gut-homing markers α4β7 and CCR9 protein were also significantly elevated in IL-13 KO compared to WT control. Collectively, our findings further corroborate that the route of vaccine delivery, tissue microenvironment and IL-13 depleted cytokine milieu can significantly alter the antigen-specific CD8+ T cell gene expression profiles and in turn modulate their functional avidities as well as homing capabilities.

Challenges in mucosal HIV vaccine development: lessons from non-human primate models

An efficacious HIV vaccine is urgently needed to curb the AIDS pandemic. The modest protection elicited in the phase III clinical vaccine trial in Thailand provided hope that this goal might be achieved. However, new approaches are necessary for further advances. As HIV is transmitted primarily across mucosal surfaces, development of immunity at these sites is critical, but few clinical vaccine trials have targeted these sites or assessed vaccine-elicited mucosal immune responses. Pre-clinical studies in non-human primate models have facilitated progress in mucosal vaccine development by evaluating candidate vaccine approaches, developing methodologies for collecting and assessing mucosal samples, and providing clues to immune correlates of protective immunity for further investigation. In this review we have focused on non-human primate studies which have provided important information for future design of vaccine strategies, targeting of mucosal inductive sites, and assessment of mucosal immunity. Knowledge gained in these studies will inform mucosal vaccine design and evaluation in human clinical trials.

Induction of Potent and Long-Lived Antibody and Cellular Immune Responses in the Genitorectal Mucosa Could be the Critical Determinant of HIV Vaccine Efficacy

The field of HIV prevention has indeed progressed in leaps and bounds, but with major limitations of the current prevention and treatment options, the world remains desperate for an HIV vaccine. Sadly, this continues to be elusive, because more than 30 years since its discovery there is no licensed HIV vaccine. Research aiming to define immunological biomarkers to accurately predict vaccine efficacy have focused mainly on systemic immune responses, and as such, studies defining correlates of protection in the genitorectal mucosa, the primary target site for HIV entry and seeding are sparse. Clearly, difficulties in sampling and analysis of mucosal specimens, as well as their limited size have been a major deterrent in characterizing the type (mucosal antibodies, cytokines, chemokines, or CTL), threshold (magnitude, depth, and breadth) and viral inhibitory capacity of HIV-1-specific immune responses in the genitorectal mucosa, where they are needed to immediately block HIV acquisition and arrest subsequent virus dissemination. Nevertheless, a few studies document the existence of HIV-specific immune responses in the genitorectal mucosa of HIV-infected aviremic and viremic controllers, as well as in highly exposed persistently seronegative (HEPS) individuals with natural resistance to HIV-1. Some of these responses strongly correlate with protection from HIV acquisition and/or disease progression, thus providing significant clues of the ideal components of an efficacious HIV vaccine. In this study, we provide an overview of the key features of protective immune responses found in HEPS, elite and viremic controllers, and discuss how these can be achieved through mucosal immunization. Inevitably, HIV vaccine development research will have to consider strategies that elicit potent antibody and cellular immune responses within the genitorectal mucosa or induction of systemic immune cells with an inherent potential to home and persist at mucosal sites of HIV entry.

Modern Vaccine Adjuvant/Formulation--Session 9: Adjuvants

The Session 9 of the Modern Vaccine Adjuvant/Formulation meeting pointed out the permanent need for vaccine improvement and for adjuvant development. Indeed, the increasing use of recombinant subunit vaccines for both parenteral and mucosal vaccination necessitates the development of improved adjuvants. This session dealt with strategies for the development of new vaccine adjuvants with respect to the availability of new molecules targeting specifically the receptors of the systemic or mucosal immune system.

From the laboratory to clinical trials and back again: lessons learned from HIV prevention trials

PROBLEM

Inadequate, irrelevant, or inappropriate timing of biological specimen collection during clinical trials is a cause for delay in understanding and explaining correlates of protection and/or effectiveness, particularly at the portal of entry in the context of sexual HIV transmission and its prevention.

METHODS

We present examples of HIV prevention trials to illustrate the impact of preplanned versus unplanned laboratory science program on the interpretation of trial results and advancement of the field.

RESULTS

Of the five completed pre-exposure prophylaxis trials, only two announced main outcome results simultaneously with data on correlates of drug-related effectiveness. In four of the vaccine trials completed, the only one that showed a protective effect presented data on protection correlates significantly later.

CONCLUSION

Clinical trials must preplan collaborative immunophysiological research and prioritize biological specimen collection and storage for enhancement of research on correlates of protection. Similarly appropriate specimens should be prioritized for pathogenesis research.

Differences in the concentration and correlation of cervical immune markers among HPV positive and negative perimenopausal women

INTRODUCTION

Women≥45years of age with persistent HPV infections have distinct peripheral circulating immune profiles. Few studies have comprehensively evaluated the cervical immunologic microenvironment in HPV-positive and HPV-negative perimenopausal women.

METHODS

We collected cervical secretion specimens from 34 high risk HPV (HR-HPV) positive and 44 HR-HPV negative women enrolled in an ongoing prospective cohort assessing the natural history of HPV across the menopausal transition. We used these specimens to quantify concentrations of 27 different immune markers using multiplexed bead-based immunoassays.

RESULTS

HR-HPV positive women had significantly higher median concentrations of IL-5 (0.11 ng/mgtotal protein vs. 0.08 ng/mgtotal protein), IL-9 (2.7 ng/mgtotal protein vs. 2.1 ng/mgtotal protein), IL-13 (2.1 ng/mgtotal protein vs. 0.9 ng/mgtotal protein), IL-17 (2.9 ng/mgtotal protein vs. 1.1 ng/mgtotal protein), EOTAXIN (4.1 ng/mgtotal protein vs. 1.1 ng/mgtotal protein), GM-CSF (4.3 ng/mgtotal protein vs. 3.3 ng/mgtotal protein), and MIP-1α (3.5 ng/mgtotal protein vs. 1.9 ng/mgtotal protein) compared to HR-HPV negative women. A shift in the correlation of T-cell and pro-inflammatory cytokines (IFN-γ, IL-5, IL-9, IL-10, IL-12, IL-13, IL-15, and TNF-α) from IL-2 to EOTAXIN was observed between HR-HPV negative and positive women.

CONCLUSIONS

Higher local concentrations of anti-inflammatory and allergy associated markers, with a shift in T-cell associated cytokine correlation from IL-2 to EOTAXIN, are associated with HPV infection among older women.

Performance of swabs, lavage, and diluents to quantify biomarkers of female genital tract soluble mucosal mediators

Background

Measurement of immune mediators and antimicrobial activity in female genital tract secretions may provide biomarkers predictive of risk for HIV-1 acquisition and surrogate markers of microbicide safety. However, optimal methods for sample collection do not exist. This study compared collection methods.

Methods

Secretions were collected from 48 women (24 with bacterial vaginosis [BV]) using vaginal and endocervical Dacron and flocked swabs. Cervicovaginal lavage (CVL) was collected with 10 mL of Normosol-R (n = 20), saline (n = 14), or water (n = 14). The concentration of gluconate in Normosol-R CVL was determined to estimate the dilution factor. Cytokine and antimicrobial mediators were measured by Luminex or ELISA and corrected for protein content. Endogenous anti-HIV-1 and anti-E. coli activity were measured by TZM-bl assay or E. coli growth.

Results

Higher concentrations of protein were recovered by CVL, despite a 10-fold dilution of secretions, as compared to swab eluents. After protein correction, endocervical swabs recovered the highest mediator levels regardless of BV status. Endocervical and vaginal flocked swabs recovered significantly higher levels of anti-HIV-1 and anti-E. coli activity than Dacron swabs (P<0.001). BV had a significant effect on CVL mediator recovery. Normosol-R tended to recover higher levels of most mediators among women with BV, whereas saline or water tended to recover higher levels among women without BV. Saline recovered the highest levels of anti-HIV-1 activity regardless of BV status.

Conclusions

Endocervical swabs and CVL collected with saline provide the best recovery of most mediators and would be the optimal sampling method(s) for clinical trials.

Rational design of HIV vaccines and microbicides: report of the EUROPRISE network annual conference 2010

Novel, exciting intervention strategies to prevent infection with HIV have been tested in the past year, and the field is rapidly evolving. EUROPRISE is a network of excellence sponsored by the European Commission and concerned with a wide range of activities including integrated developmental research on HIV vaccines and microbicides from discovery to early clinical trials. A central and timely theme of the network is the development of the unique concept of co-usage of vaccines and microbicides. This review, prepared by the PhD students of the network captures much of the research ongoing between the partners. The network is in its 5^th year and involves over 50 institutions from 13 European countries together with 3 industrial partners; GSK, Novartis and Sanofi-Pasteur. EUROPRISE is involved in 31 separate world-wide trials of Vaccines and Microbicides including 6 in African countries (Tanzania, Mozambique, South Africa, Kenya, Malawi, Rwanda), and is directly supporting clinical trials including MABGEL, a gp140-hsp70 conjugate trial and HIVIS, vaccine trials in Europe and Africa.

HIV vaccines: lessons learned and the way forward

PURPOSE OF REVIEW

An effective HIV vaccine is a global health priority. We describe lessons learned from four HIV vaccine trials that failed to demonstrate efficacy and one that showed modest protection as a pathway forward.

RECENT FINDINGS

The Merck Ad5 phase IIb T-cell vaccine failed to show efficacy and might have increased the risk of HIV acquisition in men who have sex with men. Although VaxGen gp120 alone was not efficacious in groups at high risk for HIV-1 infection, the RV144 ALVAC prime and gp120 boost regimen showed 31% efficacy in low-incidence heterosexuals. All trials demonstrated the limitations of available laboratory and animal models to assess relevant vaccine-induced immune responses and predict clinical trial outcome. Analysis of innate and adaptive responses induced in RV144 will guide future trial design.

SUMMARY

Future HIV vaccine trials should define the RV144 immune responses relevant to protection, improve durability and level of protection, and assess efficacy in diverse risk groups. New strategies examining heterologous vector prime-boost, universal inserts, replicating vectors, and novel protein or adjuvant immunogens should be explored to induce T-cell and antibody responses. HIV vaccine development requires innovative ideas and a sustained long-term commitment of scientists, governments, and the community.

Update on mucosal HIV vaccine vectors

PURPOSE OF REVIEW

HIV's primary site of infection is at mucosal surfaces. To successfully defend against sexually transmitted diseases (STDs), including HIV, protection may need to be specifically elicited at the mucosal interface, where the organism enters the host. Recent advances in measuring adaptive responses at mucosal sites and optimization of techniques for low-dose repeated mucosal challenge in nonhuman primate animal models allow more in depth studies of mucosal vaccine vectors.

RECENT FINDINGS

Although parenterally administered vaccines can elicit responses at mucosal sites, vaccination of mucosal sites is being explored in an attempt to increase the frequency, strength and distribution of the adaptive mucosal response. Recent studies in nonhuman primates involve vaccination of the gastrointestinal tract and rectum, as well as the nose, oropharynx or respiratory tree in an attempt to elicit responses at the distal mucosal sites where HIV transmission occurs, the rectum and genital tract.

SUMMARY

Recent experiments in nonhuman primates indicate that vaccination at mucosal sites can elicit robust responses in the periphery and at mucosal sites, although the response pattern varies widely by route and regimen used. For most regimens, disease course after challenge did not differ by route of vaccination.

Clinical parameters essential to methodology and interpretation of mucosal responses

Research aimed at putting an end to the HIV pandemic is dynamic given the marked advances in understanding of pathogenesis since its origin. Attention has shifted from systemic management of disease to a focus on the most common site of acquisition, the female genital tract. Research on the female genital tract of humans requires consideration of a number of specific clinical parameters. If such parameters are not considered when enrolling subjects into studies, it could lead to faulty data ascertainment. This article reviews important clinical characteristics to consider when conducting studies of the human female genital tract in regard to mucosal immunity and HIV disease. Important topics to consider include the method and source of sample collection, the individual patient characteristics, and in the case of recruitment of HIV-infected women, HIV disease characteristics.

Methodological issues in sampling the local immune system of the female genital tract in the context of HIV prevention trials

The spread of HIV continues unabated in the most vulnerable populations of the world. HIV prevention methods, such as a vaginal microbicide, a mucosal vaccine, pre-exposure prophylaxis or a vaccine, are urgently needed in the fight against new infections. We must make a commitment to supporting innovative research and product design, so that one or more of these products provide a halt to the spread of HIV. Above all, these products should be proven to be safe and not negatively disturb the local immune system in a way that facilitates or enhances heterosexual transmission of HIV. HIV specific and non specific cellular and humoral local vaginal immunity must be assessed in clinical trials when testing prevention products for safety or efficacy. A proven, well-documented and standardized sampling strategy will provide high quality data to be able to assess both safety and local immune responses. In this paper, we will discuss methods for vaginal immunology sampling in the context of clinical trials.

Development of standard operating procedures to obtain longitudinal vaginal specimens from nulliparous rabbits as part of HIV vaccine mucosal immunogenicity studies

The New Zealand white rabbit model (Oryctolagus cuniculus) is widely used to test whether HIV vaccine candidates elicit systemic antibody responses; however, its use in mucosal immunology has not been fully exploited due to the difficulty in collecting mucosal specimens longitudinally and reproducibly. Here we describe feasible and non-feasible methods to collect vaginal and nasal specimens from nulliparous rabbits. Non-feasible methods were those resulting in poor reproducibility and considerable animal twitching during sampling, whereas feasible methods resulted in no animal twitching and potential for sampling reproducibility. Standard operating procedures (SOPs) were implemented to collect vaginal swabs yielding total IgA titres ranging from 12,500 to 312,500. Intranasal immunisation with a naked DNA vaccine encoding HIV gp140 elicited HIV envelope-specific IgA detectable in nasal but not in vaginal secretions. Our methods provide an alternative to reliably assess pre- and post-vaccination mucosal antibody titres longitudinally in rabbits as part of mucosal HIV vaccine immunogenicity studies.

Factors affecting transmission of mucosal human papillomavirus

Human papillomavirus (HPV) is the most common sexually transmitted infection. The effect of HPV on public health is especially related to the burden of anogenital cancers, most notably cervical cancer. Determinants of exposure to HPV are similar to those for most sexually transmitted infections, but determinants of susceptibility and infectivity are much less well established. Gaps exist in understanding of interactions between HPV, HIV, and other sexually transmitted infections. The roles of mucosal immunology, human microbiota at mucosal surfaces, host genetic factors and hormonal concentrations on HPV susceptibility and infectivity are poorly understood, as are the level of effectiveness of some primary or secondary preventive measures other than HPV vaccination (such as condoms, male circumcision, and combination antiretroviral therapy for HIV). Prospective couples studies, studies focusing on mucosal immunology, and in-vitro raft culture studies mimicking HPV infection might increase understanding of the dynamics of HPV transmission.