REVIEW ARTICLE

Humoral Immune Responses to HIV in the Mucosal Secretions and Sera of HIV-Infected Women Jiri Mestecky1,2, Qing Wei1, Rashada Alexander1,3, Milan Raska1,4, Jan Novak1, Zina Moldoveanu1 1

Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA; Institute of Immunology and Microbiology, Faculty of Medicine, Charles University, Prague, Czech Republic; 3 Office of the Director, National Institutes of Health, Bethesda, MD, USA; 4 Department of Immunology, Faculty of Medicine, Palacky University, Olomouc, Czech Republic 2

Keywords Antibody responses, human immunodeficiency virus, mucosal immunity, secretory IgA and IgG Correspondence Jiri Mestecky, University of Alabama at Birmingham, BBRB 757, 845 19th Street South, Birmingham, AL 35294-2170, USA. E-mail: [email protected] Submission November 20, 2013; accepted December 17, 2013. Citation Mestecky J, Wei Q, Alexander R, Raska M, Novak J, Moldoveanu Z. Humoral immune responses to HIV in the mucosal secretions and sera of HIV-infected women. Am J Reprod Immunol 2014; 71: 600–607

Although sera and all external secretions contain antibodies to human immunodeficiency virus (HIV), their levels, specificity, isotypes, and relevant effector functions display a great degree of variability. Antibodies that bind HIV antigens and neutralize the virus are predominantly associated with the IgG isotype in sera and in all external secretions, even where total levels of IgG are much lower than those of IgA. Rectal fluid that contains high IgA, but low IgG levels, displayed low neutralizing activity independent of antibodies. Therefore, external secretions should be evaluated before and after selective depletion of Ig. At the systemic level, HIV-specific IgA may interfere with the effector functions of IgG, as suggested by recent studies of individuals systemically immunized with an experimental HIV vaccine. Although HIV-specific IgG and IgA antibodies may exhibit their protective activities at mucosal surfaces through interference with viral entry and local neutralization at the systemic level, such antibodies may display discordant effector functions.

doi:10.1111/aji.12203

Introduction Although the majority of bacterial and viral infections, including human immunodeficiency virus (HIV), enter the body through the large surface areas of mucosal membranes, the ensuing humoral and cellular responses are most frequently determined in sera and in lymphocytes isolated from peripheral blood; immune responses in mucosal secretions and tissues are usually not evaluated. In view of the considerable independence of the systemic and mucosal compartments of the immune system, with respect to the immunoglobulin (Ig) isotypes and tissue origin of lymphocytes, the evaluation of systemic responses may not reflect the quality and magnitude of immune responses

600

generated at the site of entry of infectious agents. Furthermore, individual mucosal sites display marked differences with respect to the dominant Ig isotypes and effector functions involved in their protective activities, as well as the phenotypes and origin of B and T cells resident in mucosal tissues.1–3 These facts are particularly relevant to HIV infections. The mucosae of the genital and gastrointestinal tracts are the most common sites of viral entry through heterosexual and homosexual encounters. Importantly, these two compartments display highly significant differences in the total levels of IgA and IgG and their molecular forms, numbers, and isotypes of antibody-secreting cells (ASC), expression of Ig-transporting receptors on epithelial cells, and local versus systemic origin of antibodies. The presence of American Journal of Reproductive Immunology 71 (2014) 600–607 ª 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

MUCOSAL RESPONSES TO HIV

mucosal inductive sites, expression of homing receptors on lymphocytes, and corresponding ligands on endothelial capillary cells, and strong hormonal influence on the total levels of Ig in the female genital tract during the menstrual cycle are also characteristic of these two compartments.1–4 The purpose of this review is to critically discuss problems encountered in the evaluation of immune responses in external secretions, emphasize the unexpected dominance of HIV binding as well as neutralizing antibodies of the IgG isotype in sera and all external secretions examined, and to identify current controversial issues encountered in the evaluation of HIV-specific responses in mucosal secretions. Problems encountered in the evaluation of humoral immune responses in external secretions of HIV-infected individuals There are no uniformly accepted mucosal collection and specimen processing methods that would allow for the generation of comparable results from individual laboratories, despite attempts to standardize these procedures.5 Although the pronounced dominance of secretory IgA (S-IgA) was observed in almost all secretions irrespective of the collection procedure, the total levels of S-IgA, and especially of IgG, in female genital tract secretions display enormous differences during the menstrual cycle.4–7 All external secretions contain Ig at much lower levels than those in serum and display enormous variabilities in their concentrations, which is true even for the same type of secretion (e.g., genital tract fluids).5 This is partially due to different collection and sample processing methods, dilution with lavage fluids, increased flow rates upon inadvertent stimulation, sensitivity to bacterial and endogenous proteases, and binding to other proteins and glycoproteins, such as mucin, and the tendency of Ig to form aggregates which interfere with precise quantitation.5 ELISA provides reliable information with respect to the HIV-specific antibodies of the IgG, but not IgA isotypes. This point was convincingly demonstrated in two extensive comparative evaluation studies of rectal or cervico-vaginal lavage fluids (RL and CVL, respectively) performed in six different laboratories.8,9 Using well-established assays, there was a remarkable concordance of results with respect to the IgG HIV-specific antibodies. In contrast, marked differences were obvious in the positivity detection, American Journal of Reproductive Immunology 71 (2014) 600–607 ª 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

as well as the levels of antibodies of the IgA isotype. This may be partly due to the differences in antigens used for plate coating and/or antibodies used for the development of ELISA. Furthermore, frequent falsepositive results were reported earlier for the measurement of HIV-specific IgA antibodies in external secretions.10 Enhanced-chemiluminescence Western blot assay (ECL-WB) has been used in several studies.8,9,11–15 Due to the high sensitivity and the ability of antibodies to react with various HIV-derived antigens, ECL-WB has generated highly reliable results for the detection of HIV-specific antibodies of both IgG and IgA isotypes. Although not quantitative, the frequency of detection was higher than that observed by ELISA. Virus neutralization (VN) assessment in external secretions presents several unavoidable problems, including low content of total Ig,5 limited volumes of obtained fluids, which have to be used at low dilutions,9,11,14 the late appearance of VN antibodies after HIV infection,16–21 as well as the presence of innate humoral factors (e.g., secretory leukocyte protease inhibitor, lactoferrin, and others22–25). Therefore, a careful choice of viruses to be used, and the selective removal of IgG and IgA is required to ascertain that the VN is indeed mediated by antibodies.14 Furthermore, serum IgG and IgA HIV-specific antibodies exhibited different patterns and variability with respect to the stage of HIV infection, including acutely infected patients, elite controllers, long term non-progressors, AIDS, and patients on HAART.20 In addition to differences in specificity of antibodies for Env proteins and peptides,8,9,21 glycans associated with HIV antigens need to be also considered. Human immunodeficiency virus gp120 is a heavily glycosylated outer component of envelope glycoprotein (Env) trimers, with ~50% of its molecular mass contributed by N-linked glycans, which are involved in the binding to the host-cell receptor and coreceptor(s) and the initial steps of cell entry and infection.26 Another aspect of Env glycosylation is related to the antibody binding; gp120 glycans serve as epitopes for some antibodies and as shields against other VN antibodies.27 HIV-1 escape variants that emerge due to the pressure of the immune system during the chronic infection exhibit diverse env sequences.28 Recent studies identified transmitted ‘founder’ virus (TFV) genome sequences and revealed that in most cases, the infection starts from transmission of a single virus or few viruses.29,30 601

MESTECKY ET AL.

Env sequences from TFV and chronic-stage virus (CSV) often differ in the number and localization of potential N-glycosylation sites (PNGS); it has been speculated that these new PNGS may generate a shield against VN antibodies.31 The differential cellspecific glycosylation of gp120 affects recognition by HIV-1-specific antibodies.32,33 It is well-established that variable PNGS on Env gp120 are a characteristic of escape variants of HIV-1. Notably, some of the VN antibodies, such as PG9 and PG16, recognize Env glycopeptides in the context of specific glycosylation of some sites.32,33 Thus, it is important for the assays concerning measurement of virus binding, as well as VN antibodies, to use well-defined and well-characterized Env or viruses with these Env variants. In view of the fact that antibodies in sera and external secretions may differ in their strict antigen specificity patterns,34 it is obvious that experiments need to be performed using sera as well as external secretions. HIV-specific humoral responses in sera and all external secretions: Dominance of IgG HIV-binding Antibodies Mucosally acquired infections or mucosal immunizations induce antigen-specific humoral immune responses dominantly of the IgA isotype at the site of infection or immunization, and in secretions of anatomically remote mucosal tissues, due to the dissemination of precursors of ASC of the IgA isotype through the common mucosal immune system.35–37 Based on the dominance of S-IgA in almost all external secretions, many studies focused on the detection of HIV-specific antibodies of the IgA isotype.1,18,38,39 However, subsequent quantitative evaluations clearly demonstrated that in contrast to the pronounced S-IgA responses induced by the majority of bacterial and viral mucosal infections,40,41 HIV responses are represented by specific antibodies of the IgG isotype.1,8,9,11,12,14,42–44 Surprisingly, the dominance of IgG HIV-specific antibodies was obvious even in secretions in which S-IgA constitutes 95% or more of total Ig (such as the intestinal fluid and saliva).12,15 This marked dominance of HIV-specific IgG was detected irrespective of the differences in ELISA protocols and HIV antigens used.8,9,15 The evaluation of the IgG subclass association of HIV-specific antibodies demonstrated their restriction to the IgG1 and IgG3.44 Interestingly, the calculations of ‘specific antibody 602

activities’ (HIV-specific versus. total IgA or IgG antibodies) in various external secretions and also in sera clearly indicated that these values are not identical for all secretions and display marked, site-specific differences.12,15,44 These findings suggest that the HIV-specific antibodies may originate both from the local synthesis in individual mucosal tissues and from a highly variable plasma contribution.12,15,44 Based on such approaches, a significant local production of HIV-specific IgG1 antibodies was convincingly demonstrated for CVL.44 Using ELISA, HIV-specific antibodies of the IgA isotype were present at low levels in the majority of samples or even absent in others.8,9,11,12,15 However, the levels of total IgA in these secretions were comparable or even higher than in those collected from noninfected individuals.8,9,12,14,15 Although present in almost all plasma/serum samples, the levels of HIVspecific IgA antibodies displayed extremely high variability and were low in comparison with IgG (for example, median values for 50 individuals were 3290 ng/mL for IgA versus. 108,000 ng/mL for IgG, respectively).15 The low levels of HIV-specific IgA in all external secretions were also observed in serum samples, suggesting that HIV in humans and simian immunodeficiency virus in macaques do not elicit pronounced IgA responses in mucosal or in systemic compartments of the immune system.8,9,12,15,45 When present, HIV-specific IgA is restricted in sera and saliva to the IgA1 subclass.39 Enumeration of ASC in peripheral blood of HIVinfected individuals corroborated serological data.12 Irrespective of the route of acquisition, length of infection, CD4+ cell counts, and viral loads, ASC specific for HIV Env gp120 or gp160 of the IgG isotype were present in statistically significant higher numbers (0.71% or 1.24%, respectively) than those of the IgA (0.15% or 0.34%) or IgM (0.45% or 0.55%) isotypes.12 In the intestinal mucosa of jejunum, ileum, and rectum, IgA ASC greatly outnumbered those producing IgG. However, when ASC of the IgG versus IgA specific for gp160 and gp120 were enumerated as the percentage of total IgG or IgA ASC, it was obvious that in the intestine, 0.2–1.2% of IgG ASC were specific for Env antigens, while only 0.02–0.25% ASC were of the IgA isotype (Z. Moldoveanu, unpublished results). In other studies,46,47 a marked increase in total ASC of all isotypes was observed in the intestinal mucosal of HIV-infected individuals, apparently due to the polyclonal B-cell activation.47 A higher relative American Journal of Reproductive Immunology 71 (2014) 600–607 ª 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

MUCOSAL RESPONSES TO HIV

frequency of ASC specific for gp160 in the IgG than the IgA isotype was observed.46 HIV-neutralizing Antibodies The protective effect of HIV-neutralizing antibodies has been demonstrated in vitro and in vivo in extensive studies performed in macaques.48–51 Therefore, the induction of such antibodies is one of the most important current efforts in HIV vaccinology.19,52,53 In the majority of studies, VN antibodies have been evaluated in the sera of HIV-infected or immunized individuals. As discussed above, the determination of VN in mucosal secretions is complicated by a number of unavoidable problems. Virus neutralization antibodies are usually induced at later stages of infection and in comparison with binding antibodies, reach low levels.1,17,19–21 With the exception of CVL and semen, in which total IgG represents the dominant Ig isotype, other secretions contain IgA at concentrations that are much higher than those of IgG.5 In view of the fact that the HIV-binding antibodies are mainly associated with the IgG isotype, the evaluation of VN in some secretions (e.g., RL fluid) is difficult.14 Furthermore, the antiviral activity of external secretions may be also mediated by many factors of innate humoral immunity, which may mask or interfere with antibody-dependent VN (see above). To avoid this problem, VN should be performed before and after selective removal of IgG and/or IgA from the secretion examined.14 This approach is feasible in contrast to the evaluation of Ig isolated from RL or CVL. The low levels of total and especially HIV-specific VN antibodies and the partial loss and denaturation of Ig molecules during desorption from affinity gels (low pH, high salt concentration, etc.,) contribute to the difficulties encountered with a reliable determination of VN activity of Ig isolated from CVL and RL. In HIVinfected individuals’ sera and external secretions, represented by CVL, VN antibodies were associated dominantly with the IgG isotype.9,14 This conclusion was confirmed by the selective removal of IgG: the VN became greatly reduced or even undetectable.14 In contrast, selective removal of IgA from sera reduced but did not abolish VN activity, indicating that IgA VN antibodies are present, but at levels much lower than those of IgG.14 In contrast to CVL, evaluation of VN in RL collected in parallel yielded results indicating that VN was mostly mediated by innate humoral factors rather than Ig: selective American Journal of Reproductive Immunology 71 (2014) 600–607 ª 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

removal of IgG and/or IgA did not substantially alter the low level of VN observed in RL samples.14 It should be emphasized that in this as well as many previous studies, properly collected RL contain (in contrast to CVL) only trace amounts of IgG5, the dominant isotype associated with VN, and the IgA present in RL in relatively larger quantities does not exhibit VN activity.14 However, VN IgA antibodies have been detected in external secretions by some, but not all investigators (for review see1). Nevertheless, it is generally agreed that HIV-specific antibodies of the IgA isotype, which in vitro display effector functions desirable for the protection against HIV infection, including VN,1,38,54–58 are not regularly induced by HIV infection or immunization with experimental HIV vaccines.1 Current controversies and future directions Although the evaluation of humoral responses in external secretions of genital and intestinal tracts of HIV-infected or vaccinated individuals is compromised by the above-described difficulties, the importance of a parallel evaluation of humoral responses in plasma/sera and relevant secretions is justified by the infrequently appreciated mutual independence in magnitude and quality of immune responses induced in the systemic and mucosal compartments.35–37 The dominant Ig isotype in most external secretions, S-IgA, is derived almost exclusively from the local production and selective receptormediated transport into external secretions.59 Several comparative studies clearly indicated the independence of IgA present in plasma and external secretions with respect to the maturation patterns, molecular forms, and particularly to effector functions, some of which are highly relevant to HIV infection. The protective function of HIV-specific IgA in mucosal protection has been demonstrated in vitro by its extracellular and intracellular VN activity, inhibition of HIV uptake by epithelial cells, and exclusion of HIV-IgA immune complexes from the epithelial cells.1,3,38,54–58,60 Unexpectedly, and in sharp contrast to this demonstrable protective effect of S-IgA, the induction of HIV Env-specific IgA responses in plasma of volunteer systemically immunized with an experimental HIV vaccine correlated directly with the higher rate of HIV infection.61 Although the reasons for this unexpected finding have not been elucidated, there are several potential mechanisms involved. It is possible that IgA bound 603

MESTECKY ET AL.

to HIV interferes with effector functions of IgG including VN, antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cell-mediated viral inhibition (ADCVI), and protection of HIV-infected cells from immunologically mediated elimination (see Tables I). This finding underlines

underappreciated differences in effector functions of IgA in mucosal and systemic compartments.62 In HIV infection, it appears that strong IgA responses in the systemic compartment may have detrimental effects, in contrast to the protective functions of S-IgA in secretions of the genital and intestinal tract

Table I Comparative effector functions of HIV-specific antibodies of IgG and IgA isotypes in the systemic and mucosal compartment of the immune system Compartment

IgG

IgA

Systemic Plasma/serum

Present in all infected individuals VN ADCC ADCVI

Present in the majority of infected individuals at low levels VN? Possible blocking of functions (VN, ADCC, ADCVI) mediated by IgG ‘Protection’ of the virus and/or virus-infected cells

Dominant Ig isotype HIV binding and VN Protective effect of antibodies ADCC in mucosal tissues? pH-dependent, FcRn-mediated IgG HIV uptake Low levels VN difficult to detect

Low or absent IgA anti-HIV responses VN in some secretions Inhibition of virus attachment Intracellular neutralization HIV-IgA excretion Low or absent HIV-specific IgA antibodies Excretion of HIV-IgA complexes

Mucosal Genital tract

Intestinal tract

ADCVI, antibody-dependent cell-mediated viral inhibition; HIV, human immunodeficiency virus; VN, virus neutralization.

Table II Paucity of HIV-specific IgA responses in HIV-infected individuals

Fluid

Isotype

Serum

IgG

IgA

Cervicovaginal lavage (CVL)

IgG

IgA

Rectal lavage (RL)

IgG

IgA

604

Total level (in lg/ml) means 15,513 18,632 28,128 2173 2405 2024 107.9 47 62.2 31.3 6 7.4 4.5 8 9.4 164.9 72 129

Frequency of HIV+ (in %)

HIV Envspecific (in lg/ml)

Specific/ Total (in %)

Virus neutralization (in %) 98–100

ELISA

WB

100 100 100 98

100 100 100 94 94

108

0.7

3.2

0.15

100

3.1

2.9

0.07

0.2

0.1

2.2

0.03

0.02

8–100 100 100 100 81 0–30 86 82 62 14 6

100 100 100 42 82 81 73 73 7.7

7.7–38.5

American Journal of Reproductive Immunology 71 (2014) 600–607 ª 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

MUCOSAL RESPONSES TO HIV

(Table I). The potential mechanisms involved in the suppression of IgA and IgG2 HIV-specific antibodies were recently elucidated and are apparently mediated by the interaction of HIV-infected dendritic cells, producing Nef, which upon contact with relevant B cells, selectively inhibit their differentiation, and production of IgA and IgG2 antibodies.63,64 The levels and spectra of antigen-specific antibodies, and effector functions of IgG antibodies in plasma/serum and external secretions also display marked differences (Table II), some of which may be relevant to HIV-specific humoral responses. In the macaque models, systemically or vaginally administered monoclonal VN HIV-specific antibodies of the IgG isotype protected animals against intravaginal SHIV challenge.48–51 Effective transport of IgG from the circulation and also from local production in the genital tract65,66 is mediated by the FcRn receptor expressed on epithelial cells.65 Most recent in vitro generated results indicate that the FcRn-mediated and pH-dependent transport of IgG also enhances transcytosis of IgG-bound HIV across intact monolayers of epithelial cells of genital, as well as intestinal origin.67 Interestingly, the FcRn-mediated transport as well as IgG-dependent ADCVI are influenced by the glycosylation pattern of IgG in that only fully glycosylated molecules react with corresponding cellular receptors; alterations and deficiencies of terminal glycan residues result in the diminished receptor reactivity.68,69 Consequently, the vaginal pH and the glycosylation pattern of IgG may play an important role in the protection or enhanced acquisition of HIV infection. Based on the marked immunologic differences in the systemic and mucosal compartments, as well as the unique immunologic characteristics of the genital and intestinal tract, with respect to the magnitude, quality, and duration and Ig isotype-dependent effector functions, the mucosal humoral immune responses should be evaluated in parallel with responses in the systemic compartment. Acknowledgements This work was supported by grants from NIH-NIAID (PO1 AI083027; R21 AI083613), a Pilot Grant from the University of Alabama at Birmingham (UAB) School of Medicine, a grant from UAB Immunology, Autoimmunity, and Transplantation Strategic Planning and a Developmental Grant from UAB CFAR (P30 AI027767). American Journal of Reproductive Immunology 71 (2014) 600–607 ª 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

Conflict of interest None. References 1 Mestecky J: Humoral immune responses to the human immunodeficiency virus type-1 (HIV-1) in the genital tract as compared to other mucosal sites. J Reprod Immunol 2007; 73:86–97. 2 Mestecky J, Moldoveanu Z, Smith PD, Hel Z, Alexander RC: Mucosal immunology of the genital and gastrointestinal tracts and HIV-1 infection. J Reprod Immunol 2009; 83:196–200. 3 Mestecky J, Raska M, Alexander RC, Moldoveanu Z: Antibody– mediated protection and the mucosal immune system of the genital tract: relevance to vaccine design. J Reprod Immunol 2010; 85:81–85. 4 Wira C, Fahley J: A new strategy to understand how HIV infects women: identification of a window of vulnerability during the menstrual cycle. AIDS 2008; 22:1909–1917. 5 Jackson S, Mestecky J, Moldoveanu Z, Spearman P: Appendix I: collection and processing of human mucosal secretions. In Mucosal Immunology, 3rd edn. J Mestecky, ME Lamm, L Mayer, W Strober, J Bienenstock, JR McGhee, L Mayer (eds). Amsterdam, The Netherlands, Elsevier Academic Press, 2005, pp 1647–1659. 6 Kutteh WH, Mestecky J, Wira CR: Mucosal immunity in the human female reproductive tract. In Mucosal Immunology, J Mestecky, ME Lamm, L Mayer, W Strober, J Bienenstock, JR McGhee, L Mayer (eds). Amsterdam, The Netherlands, Elsevier Academic Press, 2005, pp 1631–1646. 7 Kutteh WH, Prince SJ, Hammonds KR, Kutteh CC, Mestecky J: Variations in immunoglobulins and IgA subclasses of human uterine cervical secretions around the time of ovulation. Clin Exp Immunol 1996; 104:538–542. 8 Wright PF, Kozlowski PA, Rybczyk GK, Goepfert P, Staats HF, VanCott TC, Trabottoni D, Sannella E, Mestecky J: Detection of mucosal antibodies in HIV type 1-infected individuals. AIDS Res Hum Retroviruses 2002; 18:1291–1300. 9 Mestecky J, Wright PF, Lopalco L, Staats HF, Kozlowski PA, Moldoveanu Z, Alexander RC, Kulhavy R, Pastori C, Maboko L, Riedner G, Zhu Y, Wrinn T, Hoelscher M: Scarcity or absence of humoral immune responses in the plasma and cervicovaginal lavage fluids of heavily HIV-1-exposed but persistently seronegative women. AIDS Res Hum Retroviruses 2011; 27:469–486. 10 Jackson S, Prince S, Kulhavy R, Mestecky J: False positivity of enzyme-linked immunosorbent assay for measurement of secretory IgA antibodies directed at HIV-1 antigens. AIDS Res Hum Retroviruses 2000; 16:595–602. 11 Moldoveanu Z, Mestecky J: Mucosal antibody responses to HIV. In HIV Protocols, 2nd edn. VR Prasad, GV Kalpana (eds). New York, Humana Press ⁄ Springer Science, Methods Mol Biol 2009; 48: pp333–345. 12 Mestecky J, Jackson S, Moldoveanu Z, Nesbit LR, Kulhavy R, Prince S, Sabbaj S, Mulligan MJ, Goepfert PA: Paucity of antigenspecific IgA responses in sera and external secretions of HIV-1infected individuals. AIDS Res Hum Retroviruses 2004; 20:972–988. 13 Mohamed OA, Ashley R, Goldstein A, McElrath J, Dalessio J, Corey L: Detection of rectal antibodies to HIV-1 by a sensitive chemiluminescent western blot immunodetection method. J Acquir Immune Defic Syndr 1994; 7:375–380.

605

MESTECKY ET AL.

14 Wei Q, Moldoveanu Z, Huang WQ, Alexander RC, Goepfert PA, Mestecky J: Comparative evaluation of HIV-1 neutralization in external secretions and sera of HIV-1-infected women. Open AIDS J 2012; 6:293–302. 15 Mestecky J, Alexander RC, Wei Q, Moldoveanu Z: Methods of evaluation of humoral immune responses in human genital tract secretions. Am J Reprod Immunol 2011; 65:361–367. 16 Tamaras GD, Haynes BF: HIV-1-specific antibody responses during acute and chronic HIV-1 infection. Curr Opin HIV AIDS 2009; 4:373–379. 17 Overbaugh J, Morris L: The antibody response against HIV-1. In Cold Spring Harbor Perspectives In Medicine, FD Bushman, GJ Nabel, R Swanstrom (eds). Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 2012, pp 1–19. 18 Alexander R, Mestecky J: Neutralizing antibodies in mucosal secretions: IgG or IgA? Curr HIV Res 2007; 5:588–593. 19 Kwong PD, Mascola JR, Nabel GJ: Rational design of vaccines to elicit broadly neutralizing antibodies to HIV-1. In Cold Spring Harbor Perspectives in Medicine, FD Bushman, GJ Nabel, R Swanstrom (eds). Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 2011, pp 1–17. 20 Vaine M, Duenas-Decamp M, Peters P, Liu Q, Arthos J, Wang S, Clapham P, Lu S: Two closely related Env antigens from the same patient elicited different spectra of neutralizing antibodies against heterologous HIV-1 isolates. J Virol 2011; 85:4927–4936. 21 Brombin C, Diomede L, Tudor D, Drillet AS, Pastori C, Poli E, Riva A, Uberti-Foppa C, Galli M, Di Serio C, Bomsel M, Lopalco L: A nonparametric procedure for defining a new humoral immunologic profile in a pilot study on HIV infected patients. PLoS ONE 2013; 8:1–13. 22 Mcneely TB, Dealy M, Dripps DJ, Orenstein JM, Eisenberg SP, Wahl SM: Secretory leukocyte protease inhibitor:a human saliva protein exhibiting anti-human immunodeficiency virus 1 activity in vitro. J Clin Invest 1995; 96:456–464. 23 Wahl SM, McNeely TB, Janoff EN, Shugars D, Worley P, Tucker C, Orenstein JM: Secretory leukocyte protease inhibitor (SLPI) in mucosal fluids inhibits HIV-1. Oral Dis 1997; 3:64–69. 24 Kazmi SH, Naglik JR, Sweet SP, Evans RW, O’Shea S, Banatvala JE, Challacombe SJ: Comparison of human immunodeficiency virus type 1-specific inhibitory activities in saliva and other human mucosal fluids. Clin Vaccine Immunol 2006; 13:1111–1118. 25 Orsi N: The antimicrobial activity of lactoferrin: current status and perspectives. Biometals 2004; 17:189–196. 26 Raska M, Novak J: Involvement of envelope-glycoprotein glycans in HIV-1 biology and infection. Arch Immunol Ther Exp 2010; 58:191– 208. 27 Kwong PD, Wyatt R, Robinson J, Sweet RW, Sodroski J, Hendrickson WA: Structure of an HIV gp120 envelope glycoprotein in complex with the CD4 receptor and a neutralizing human antibody. Nature 1998; 393:648–659. 28 Saag MS, Hahn BH, Gibbons J, Li Y, Parks ES, Parks WP, Shaw GM: Extensive variation of human immunodeficiency virus type-1 in vivo. Nature 1988; 334:440–444. 29 Keele BF, Giorgi EE, Salazar-Gonzalez F, Decker JM, Pham KT, Salazar MG, Sun C, Grayson T, Wang S, Li H, We X, Jiang C, Kirchherr JL, Gao F, Anderson JA, Ping LH, Swanstrom R, Tomaras GD, Blattner WA, Goepfert PA, Kilby JM, Saag MS, Delwart EL, Busch MP, Cohen MS, Montefiori DC, Haynes BF, Gaschen B, Athreya GS, Lee HY, Wood N, Seoighe C, Perelson AS, Bhattacharya T, Korber BT, Hahn BH, Shaw GM: Identification and characterization of transmitted and early founder virus envelopes in

606

30

31

32

33

34

35

36 37

38

39

40

41

42

43

primary HIV-1 infection. Proc Natl Acad Sci USA 2008; 105:7552– 7557. Salazar-Gonzalez JF, Salazar MG, Keele BF, Learn GH, Giorgi EE, Li H, Decker JM, Wang S, Baalwa J, Kraus MH, Parrish NF, Shaw KS, Guffey MB, Bar KJ, Davis KL, Oshenbauer-Jambor C, Kappes JC, Saag MS, Cohen MS, Mulenga J, Derdeyn CA, Allen S, Hunter E, Markowitz M, Hraber P, Perelson AS, Bhattacharya T, Haynes BF, Korber BT, Hahn BH, Shaw GM: Genetic identity, biological phenotype, and evolutionary pathways of transmitted/founder viruses in acute and early HIV-1 infection. J Exp Med 2009; 206:1273–1289. Wei X, Decker JM, Wang S, Hui H, Kappes JC, Wu X, Salazar MG, Kilby JM, Saag MS, Komarova NL, Nowak MA, Hahn BH, Kwong PD, Shaw GM: Antibody neutralization and escape by HIV-1. Nature 2003; 422:307–312. Raska M, Takahashi K, Czernekova L, Zachova K, Hall S, Moldoveanu Z, Elliott MC, Wilson L, Brown R, Jancova D, Barnes S, Vrbkova J, Tomana M, Smith PD, Mestecky J, Renfrow MB, Novak J: Glycosylation patterns of HIV-1 gp120 depend on the type of expressing cells and affect antibody recognition. J Biol Chem 2010; 285:20860–20869. Amin MN, McLellan JS, Huang W, Orwenyo J, Burton DR, Koff WC, Kwong PD, Wang LX: Synthetic glycopeptides reveal the glycan specificity of HIV-neutralizing antibodies. Nat Chem Biol 2013; 9:521–526. Berneman A, Belec L, Fischetti VA, Bouvet JP: The specificity patterns of human immunoglobulin G antibodies in serum differ from those in autologous secretions. Infect Immun 1998; 66:4163– 4168. Mestecky J, Moldovenu Z, Russell MW: Immunologic uniqueness of the genital tract: challenge for vaccine development. Am J Reprod Immunol 2005; 53:208–214. Russell MW, Mestecky J: Humoral immune responses to microbial infections in the genital tract. Microbes Infect 2002; 4:667–677. Mestecky J: The common mucosal immune system and current strategies for induction of immune responses in external secretions. J Clin Immunol 1987; 7:265–276. Hur EM, Patel SN, Shimizu S, Rao DS, Gnanapragasam PNP, Sung An D, Yang L, Baltimore D: Inhibitory effect of HIV-specific neutralizing IgA on mucosal transmission of HIV in humanized mice. Blood 2012; 120:4571–4582. Kozlowski PA, Jackson S: Serum IgA subclasses and molecular forms in HIV infection: selective increase in monomer and apparent restriction of the antibody response to IgA1 antibodies mainly directed at env glycoproteins. AIDS Res Hum Retroviruses 1992; 8:1773–1780. Murphy BR: Mucosal immunity to viruses. In Mucosal Immunology, 3rd edn. J Mestecky, ME Lamm, W Strober, J Bienenstock, JR McGhee, L Mayer (eds). Amsterdam, The Netherlands, Elsevier Academic Press, 2005, pp 799–813. Holmgren J, Svennerholm A-M: Mucosal immunity to bacteria. In Mucosal Immunology, 3rd edn. J Mestecky, ME Lamm, W Strober, J Bienenstock, JR McGhee, L Mayer (eds). Amsterdam, The Netherlands, Elsevier Academic Press, 2005, pp 783–798. Raux M, Finkielsztejn L, Salmon-Ceron D, Bouchez H, Excler JL, Dulioust E, Grouin JM, Sicard D, Blondeau C: Development and standardization of methods to evaluate the antibody response to an HIV-1 candidate vaccine in secretions and sera of seronegative vaccine recipients. J Immunol Methods 1999; 222:111–124. Raux M, Finkielsztejn L, Salmon-Ceron D, Bouchez H, Excler JL, Dulioust E, Grouin JM, Sicard D, Bloudeau C: Comparison of American Journal of Reproductive Immunology 71 (2014) 600–607 ª 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

MUCOSAL RESPONSES TO HIV

44

45

46

47

48

49

50

51

52

53 54

55

56

antibodies in serum and various mucosal fluids of HIV type 1infected subjects. AIDS Res Hum Retroviruses 1999; 15:1365–1376. Raux M, Finkielsztejn L, Salmon-Ceron D, Bouchez H, Excler JL, Dulioust E, Gouin E, Sicard D, Blondeau C: IgG subclass distribution in serum and various mucosal fluids of HIV type 1infected subjects. AIDS Res Hum Retroviruses 2000; 6:583–594. Chaoul N, Burelout C, Peruchon S, van Buu BN, Laurent P, Proust A, Raphael M, Garraud O, Le Grand R, Prevot S, Richard Y: Default in plasma and intestinal IgA responses during acute infection by simian immunodeficiency virus. Retrovirology 2012; 9:43. Eriksson K, Kilander A, Hagberg L, Norkrans G, Holmgren J, Czerkinsky C: Virus-specific antibody production and polyclonal Bcell activation in the intestinal mucosa of HIV-infected individuals. AIDS 1995; 9:695–700. Eriksson K, Kilander A, Hagberg L, Norkrans G, Holmgren J, Czerkinsky C: Induction and expression of intestinal humoral immunity in HIV-infected individuals: prospects for vaccination against secondary enteric infections. Pathobiology 1998; 66: 176–182. Burton DR, Hessell AJ, Keele BF, Klasse PJ, Ketas TA, Moldt B, Dunlop DC, Poignard P, Doyle LA, Cavacini L, Veazey RS, Moore JP: Limited or no protection by weakly or nonneutralizing antibodies against vaginal SHIV challenge of macaques compared with a strongly neutralizing antibody. Proc Natl Acad Sci USA 2011; 108:11181–11186. Mascola JR: Passive transfer studies to elucidate the role of antibody-mediated protection against HIV-1. Vaccine 2002; 20:1922– 1925. Veazey RS, Shattock RJ, Pope M, Kirijan JC, Jones J, Hu Q, Ketas T, Marx PA, Klasse PJ, Burton DR, Moore JP: Prevention of virus transmission to macaque monkeys by a vaginally applied monoclonal antibody to HIV-1 gp120. Nat Med 2003; 9:343–346. Parren PW, Marx PA, Hessell AJ, Luckay A, Harouse J, ChengMayer C, Moore JP, Burton DR: Antibody protects macaques against vaginal challenge with a pathogenic R5 simian/human immunodeficiency virus at serum levels giving complete neutralization in vitro. J Virol 2001; 75:8340–8347. Walker LM, Burton DR: Rational antibody-based HIV-1 vaccine design: current approaches and future directions. Curr Opin Immunol 2010; 22:1–9. Mascola JR: Define the protective antibody response for HIV-1. Curr Mol Med 2003; 3:209–216. Lamm ME: Protection of mucosal epithelia by IgA: intracellular neutralization and excretion of antigens. In Mucosal Immune Defense: Immunoglobuin A, CS Kaetzel (ed). New York, Springer Science+Business Media, LLC, 2007, pp 173–182. Mantis NJ, Palaia J, Hessell AJ, Mehta S, Zhu Z, Corthesy B, Neutra MR, Burton DR, Janoff EN: Inhibitionof HIV-1 infectivity and epithelial cell transfer by human monoclonal IgG and IgA antibodies carrying the b12 V region. J Immunol 2007; 179:3144– 3152. Wright A, Lamm ME, Huang YT: Excretion of human immunodeficiency virus type 1 through polarized epithelium by immunoglobulin A. J Virol 2008; 82:11526–11535.

American Journal of Reproductive Immunology 71 (2014) 600–607 ª 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

57 Huang YT, Wright A, Gao X, Kulick L, Yan H, Lamm M: Intraepithelial cell neutralization of HIV-1 replication. J Immunol 2005; 174:4828–4835. 58 Dembert T, Robert-Guroff M: Mucosal immunity and protection against HIV ⁄ SIV infection: strategies and challenges for vaccine design. Int Rev Immunol 2009; 28:20–48. 59 Woof JM, Mestecky J: Mucosal Immunoglobulins. Immunol Rev 2005; 206:64–82. 60 Mestecky J, Russell MW: Specific antibody activity, glycan heterogeneity and polyreactivity contribute to the protective activity of S-IgA at mucosal surfaces. Immunol Lett 2009; 124:57–62. 61 Haynes BF, Gilbert PB, McElrath MJ, Zolla-Pazner S, Tomaras GD, Alam SM, Evans DT, Montefiori DC, Karnasuta C, Sutthent R, Liao H-X, DeVico AL, Lewis GK, Williams C, Pinter A, Fong Y, Janes H, DeCamp A, Huang Y, Rao M, Billings E, Karasavvas N, Robb ML, Ngauy V, deSouza MS, Paris R, Ferrari G, Bailer RT, Soderberg KA, Andrews C, Berman PW, Frahm N, De Rosa SC, Alpert MD, Yates NL, Shen X, Koup RA, Pitisuttithum P, Kaewkungwal J, Nitayaphan S, Rerks-Ngarm S, Michael NL, Kim JH: Immunecorrelates analysis of an HIV-1 vaccine efficacy trail. N Engl J Med 2012; 366:1275–1286. 62 Russell MW, Kilian M: Biological activities of IgA. In Mucosal Immunology, 3rd edn. J Mestecky, ME Lamm, W Strober, J Bienenstock, JR McGhee, L Mayer (eds). Amsterdam, The Netherlands, Elsevier Academic Press, 2005, pp 267–289. 63 Xu W, Santini PA, Sullivan JS, He B, Shan M, Ball SC, Dyer WB, Ketas TJ, Chadburn A, Cohen-Gould L, Knowles DM, Chiu A, Sanders RW, Chen K, Cerutti A: HIV-1 evades virus-specific IgG2 and IgA responses by targeting systemic and intestinal B cells via long-range intercellular conduits. Nat Immunol 2009; 10:1008–1017. 64 Qiao X, He B, Chiu A, Knowles DM, Chadburn A, Cerutti A: Human immunodeficiency virus 1 Nef suppresses CD40-dependent immunoglobulin class switching in bystander B cells. Nat Immunol 2006; 7:302–310. 65 Li Z, Palaniyandi S, Zeng R, Tuo W, Roopenian DC, Zhu X: Transfer of IgG in the female genital tract by MHC class I-related neonatal Fc receptor (FcRn) confers protective immunity to vaginal infection. Proc Natl Acad Sci USA 2011; 108:4388–4393. 66 Crowley-Nowick PA, Bell M, Edwards RP, McCallister D, Gore H, Kanbour-Shakir A, Mestecky J, Partridge EE: Normal uterine cervix: characterization of isolated lymphocyte phenotypes and immunoglobulin secretion. Am J Reprod Immunol 1995; 34:214–247. 67 Gupta S, Becerra JC, Gach JS, Phan TB, Pudney J, Moldoveanu Z, Joseph SB, Landucci G, Supnet MJ, Ping L-H, Corti D, Moldt B, Lanzavecchia A, Ruprecht RM, Burton DR, Mestecky J, Anderson DJ, Forthal DN: The neonatal Fc receptor (FcRn) enhances transcytosis of IgG-bound HIV-1 across intact epithelial monolayers. PLoS Pathog 2013; 9:e1003776. 68 Kibe T: Glycosylation and placental transport of immunologlobulin G. J Clin Biochem Nutr 1996; 21:57–63. 69 Forthal DN, Gash JS, Landucci G, Jez J, Strasser R, Kunert R, Steinkellner H: Fc-glycosylation influences receptor binding and cell-mediated anti-HIV activity of monoclonal antibody 2G12. J Immunol 2010; 185:6876–6882.

607