Cationic polypeptides are required for anti-HIV-1 activity of human vaginal fluid

Polyanionic candidate microbicides accelerate the formation of semen-derived amyloid fibrils to enhance HIV-1 infection

Polyanionic candidate microbicides, including cellulose sulfate, carrageenan, PRO 2000, were proven ineffective in preventing HIV-1 transmission and even cellulose sulfate showed increased risk of HIV acquisition in the Phase III efficacy trials. Semen plays critical roles in HIV-1 sexual transmission. Specifically, amyloid fibrils formed by fragments of prostatic acidic phosphatase (PAP) in semen termed semen-derived enhancer of virus infection (SEVI) could drastically enhance HIV-1 infection. Here we investigated the interaction between polyanions and PAP248-286, a prototype peptide of SEVI, to understand the possible cause of polyanionic candidate microbicides to fail in clinical trials. We found anionic polymers could efficiently promote SEVI fibril formation, most likely mediated by the natural electrostatic interaction between polyanions and PAP248-286, as revealed by acid native PAGE and Western blot. The overall anti-HIV-1 activity of polyanions in the presence or absence of PAP248-286 or semen was evaluated. In the viral infection assay, the supernatants of polyanions/PAP248-286 or polyanions/semen mixtures containing the free, unbound polyanionic molecules showed a general reduction in antiviral efficacy, while the pellets containing amyloid fibrils formed by the polyanion-bound PAP248-286 showed aggravated enhancement of viral infection. Collectively, from the point of drug-host protein interaction, our study revealed that polyanions facilitate SEVI fibril formation to promote HIV-1 infection, thus highlighting a molecular mechanism underlying the failure of polyanions in clinical trials and the importance of drug-semen interaction in evaluating the anti-HIV-1 efficacy of candidate microbicides.

Proteomic analysis of human cervicovaginal fluid collected before preterm premature rupture of the fetal membranes

A significant obstetric complication facing contemporary materno–fetal medicine is preterm premature rupture of the fetal membranes (preterm PROM), which occurs in 30% of all preterm births. The objective of this study was to identify differentially expressed proteins in the cervicovaginal fluid of asymptomatic women before the clinical manifestation of preterm PROM. The preterm PROM group comprised of women with samples collected 6–23 days before PROM, who subsequently delivered preterm (n=5). Women who spontaneously delivered at term served as gestation-matched controls (n=10). Two-dimensional difference in-gel electrophoresis was used to distinguish differential expression between the pooled groups and fold changes were subsequently confirmed by two-dimensional PAGE of individual samples. Spots of interest were identified by mass spectrometry. Proteins that were significantly reduced with impending preterm PROM included the following: thioredoxin (2.7-fold), interleukin 1 receptor antagonist (1.7-fold), fatty acid-binding protein 5 (2.1-fold), cystatin A (dimer; 1.9-fold), monocyte/neutrophil elastase inhibitor (1.6-fold), squamous cell carcinoma antigen-1 (2.1-fold) and γ-glutamyl cyclotransferase (3.0-fold). By contrast, annexin A3 (3.7-fold) and vitamin D binding protein (3.9-fold) were significantly increased with impending preterm PROM. Western blot analysis was also performed on an independent cohort of preterm PROM and control samples to validate these candidate biomarkers. These proteins have known biological functions in oxidative balance, anti-inflammatory activity, metabolism or protease inhibition that may facilitate membrane rupture.

Amniotic fluid exhibits an innate inhibitory activity against HIV type 1 replication in vitro

Indirect evidence suggests that amniotic fluid (AF) may play a role in the pathogenesis of in utero HIV-1 transmission. The purpose of this study was to evaluate the potential innate inhibitory role of AF on HIV replication, which may contribute to protection of the fetus against intrauterine transmission. AF was collected from term HIV-1-negative women undergoing scheduled cesarean section. The inhibitory effect of AF against HIV-1(BA-L) replication was tested in vitro with or without the addition of protease inhibitor cocktail (PIC) in PHA-stimulated PBMC cultures. Quantitative measurement of human neutrophil peptides 1-3 (HNP1-3) was performed on all AF samples, using an ELISA assay. AF exhibited a dose-dependent inhibitory activity against HIV-1(BA-L) replication, with all samples (n=12) reaching significant inhibitory effect using 50% AF. In vitro, this activity decreased over time, but was able to be sustained with the addition of PIC. The HNP1-3 concentration in AF samples (n=12) ranged from undetectable (<41 pg/ml, n=3) to >250,000 pg/ml with a median of 5,146 pg/ml. AF exhibited a significant and dose-dependent innate inhibitory activity against HIV-1 replication, which was present in all AF samples tested. This effect was prolonged in the presence of PIC, suggesting that the inhibitory factor was in the cell-free protein fraction. The HNP1-3 concentration in AF was in the subinhibitory range for HIV with no correlation between its concentration and the HIV-1 inhibitory activity. These data show the presence of a significant innate inhibitory activity against HIV in AF.

Anti-HIV-1 activity of elafin depends on its nuclear localization and altered innate immune activation in female genital epithelial cells

Elafin (E) and its precursor trappin-2 (Tr) are alarm antiproteases with antimicrobial and immunomodulatory activities. Tr and E (Tr/E) have been associated with HIV-1 resistance. We recently showed that Tr/E reduced IL-8 secretion and NF-κB activation in response to a mimic of viral dsRNA and contributed to anti-HIV activity of cervicovaginal lavage fluid (CVL) of HIV-resistant (HIV-R) commercial sex workers (CSWs). Additionally, Tr, and more so E, were found to inhibit attachment/entry and transcytosis of HIV-1 in human endometrial HEC-1A cells, acting through virus or cells. Given their immunomodulatory activity, we hypothesized that Tr/E could exert anti-HIV-1 activity at multiple levels. Here, using tagged and untagged Tr/E proteins, we comparatively evaluated their protease inhibitory, anti-HIV-1, and immunomodulatory activities, and cellular distribution. E appeared to function as an autocrine/paracrine factor in HEC-1A cells, and anti-HIV-1 activity of E depended on its unmodified N-terminus and altered cellular innate activation, but not its antiprotease activity. Specifically, exogenously added N-terminus-unmodified E was able to enter the nucleus and to reduce viral attachment/entry and transcytosis, preferentially affecting R5-HIV-1(ADA), but not X4-HIV-1(IIIB). Further, anti-HIV-1 activity of E was associated with significantly decreased HIV-1-triggered IL-8 release, attenuated NF-κB/p65 nuclear translocation, and significantly modulated mRNA expression of innate sensors TLR3 and RIG-I in HEC-1A cells. Most importantly, we found that elevated Tr/E in CVLs of HIV-R CSWs were associated with lower mRNA levels of TLRs 2, 3, 4 and RIG-I in the genital ECs from this cohort, suggesting a link between Tr/E, HIV-1 resistance and modulated innate viral recognition in the female genital mucosa. Collectively, our data indicate that unmodified N-terminus is critical for intranuclear localization and anti-HIV-1 activity of E. We also propose that E-mediated altered cellular innate activation most likely contributes to the HIV-R phenotype of these subjects.

Changes in the soluble mucosal immune environment during genital herpes outbreaks

BACKGROUND

Genital tract secretions provide variable inhibitory activity against herpes simplex virus (HSV) ex vivo. We hypothesize that the anti-HSV activity may prevent the spread of virus from the more commonly affected sites, such as the external genitalia, to the upper genital tract.

METHODS

The antimicrobial activity of cervicovaginal lavage (CVL) and concentrations of mucosal immune mediators were measured in 10 HIV-seronegative women with an active external herpetic lesion and compared with 10 HIV-seronegative women who were HSV-1 and HSV-2 seronegative. Samples were obtained at the time of a symptomatic external lesion (day 0), after 1 week of oral acyclovir (day 7), and 1 week after completing treatment (day 14). Controls were evaluated at parallel intervals.

RESULTS

The anti-HSV activity was higher in CVL obtained from cases compared to controls at presentation (day 0) (54.3% vs. 28%), fell to similar levels on day 7, and then rebounded on day 14 (69% vs. 25%). The anti-HSV activity correlated positively and significantly with the concentrations of several inflammatory proteins; the concentrations of these proteins tended to be higher in cases compared with controls and followed a similar temporal pattern.

CONCLUSIONS

Increases in inflammatory immune mediators and anti-HSV activity were detected in CVL at the time of clinical outbreaks and after completion of a short course of acyclovir. These mucosal responses may protect against HSV spread but could facilitate HIV infection and contribute to the clinical observation that, independent of clinical lesions, HSV-2 is a risk factor for HIV acquisition.

Genital tract viral load in HIV Type 1-positive women correlates with specific cytokine levels in cervical-vaginal secretions but is not a determinant of infectious virus or anti-HIV activity

As the AIDS epidemic continues with women being disproportionately affected, it is crucial to understand factors that predict the risk of heterosexual HIV-1 transmission. We investigated whether genital tract viral load (GTVL) in cervical-vaginal lavages (CVL) from HIV-1-positive women with moderately low CD4 T cell counts correlates with cytokine levels, antimicrobial concentrations, and intrinsic anti-HIV activity. CVL were collected from 19 HIV-1-positive women with moderately low CD4 T cell counts [mean 381 cells/mm(3) (227-536 cells/mm(3))]. None of the women was on antiretroviral therapy. The women were categorized into those with detectable GTVL or those with undetectable GTVL (detectable GTVL RNA levels > 400 copies/ml). Women were also categorized according to bacterial vaginosis (BV) status irrespective of GTVL. The TZM-bl assay was used to determine the presence of infectious virus and anti-HIV activity. Significantly higher levels of RANTES, Eotaxin, Fractalkine, IL-1α, IL-6, MCP-1, MIP1β, MIP1α, TNF-α, and GM-CSF were observed in women with detectable GTVL compared to women with undetectable GTVL. No significant differences were observed in the following cytokines and chemokines: G-CSF, IL-1RA, IL-8, and IP-10. GTVL did not correlate either with antimicrobials known to have anti-HIV activity or with the presence of infectious virus. BV status did not have a significant effect on anti-HIV activity. These findings further our understanding of the role of GTVL in determining the cytokine and chemokine milieu in the female reproductive tract.

Inhibition of HIV-1 infection by human α-defensin-5, a natural antimicrobial peptide expressed in the genital and intestinal mucosae

BACKGROUND

α-defensin-5 (HD5) is a key effector of the innate immune system with broad anti-bacterial and anti-viral activities. Specialized epithelial cells secrete HD5 in the genital and gastrointestinal mucosae, two anatomical sites that are critically involved in HIV-1 transmission and pathogenesis. We previously found that human neutrophil defensins (HNP)-1 and -2 inhibit HIV-1 entry by specific bilateral interaction both with the viral envelope and with its primary cellular receptor, CD4. Despite low amino acid identity, human defensin-5 (HD5) shares with HNPs a high degree of structural homology.

METHODOLOGY/PRINCIPAL FINDINGS

Here, we demonstrate that HD5 inhibits HIV-1 infection of primary CD4(+) T lymphocytes at low micromolar concentration under serum-free and low-ionic-strength conditions similar to those occurring in mucosal fluids. Blockade of HIV-1 infection was observed with both primary and laboratory-adapted strains and was independent of the viral coreceptor-usage phenotype. Similar to HNPs, HD5 inhibits HIV-1 entry into the target cell by interfering with the reciprocal interaction between the external envelope glycoprotein, gp120, and CD4. At high concentrations, HD5 was also found to downmodulate expression of the CXCR4 coreceptor, but not of CCR5. Consistent with its broad spectrum of activity, antibody competition studies showed that HD5 binds to a region overlapping with the CD4- and coreceptor-binding sites of gp120, but not to the V3 loop region, which contains the major determinants of coreceptor-usage specificity.

CONCLUSION/SIGNIFICANCE

These findings provide new insights into the first line of immune defense against HIV-1 at the mucosal level and open new perspectives for the development of preventive and therapeutic strategies.

Salivary basic proline-rich proteins are elevated in HIV-exposed seronegative men who have sex with men

OBJECTIVE

Innate mucosal factors are associated with protection in HIV-exposed seronegative (HESN) individuals, but studies of MSM have been very limited. We performed proteomic analysis of saliva from a cohort of HESN MSM who have regular unprotected oral receptive intercourse with their HIV-infected partner.

METHODS

Saliva samples from HESN (n = 25) and non-exposed male controls (n = 22) were analyzed by 2D-LC mass spectrometry. An overexpressed innate protein factor was further characterized by immunoblot, and compared with CC-chemokine expression, HIV-neutralizing activity, clinical factors, and sexual behavior.

RESULTS

Of 337 total proteins, seven were identified as differentially abundant in the HESN group. The five overabundant proteins (Basic salivary proline-rich proteins (bPRP) 2 and 3, Histatin-3, Lysozyme C, and SLPI) have known antimicrobial activity. bPRP2 showed the highest overabundance (>six-fold) in HESN individuals compared with controls (P = 0.009), including multiple isoforms. Salivary bPRP2 correlated with CC-chemokine levels in HESN individuals including RANTES (P = 0.02), MIP-1-alpha (P = 0.01), MIP-1-beta (P = 0.0002), MCP-1 (P = 0.005) and Eotaxin (P = 0.003) but not with frequency of HIV neutralizing activity, oral sexual practices, or viral load of the sexual partner.

CONCLUSION

This study identifies salivary bPRP2 as a novel soluble factor elevated in the oral compartment of HIV-exposed MSM.

[Innate and adaptative immunity of the female genital tract]

Most of molecules and cells involved in both types, innate and adaptive immunity are present within the feminine genital tract. This article attempts to list some of the various actors involved in these immunities, essentially at the vaginal level and to illustrate their implications in the most frequent pathologies. Among these molecules: defensins, collectins lysozyme, lactoferrin, calprotectin, SLP1, HSP and many others as well as Toll receptors and immunoglobulins (IgG and IgA) play a major role. Epithelial cells, antigen presenting cells, lymphocytes T, B, NK also contribute efficiently to the defenses in a coordinated way partially under the influence of sex hormones. The therapeutic perspectives, of which vaccines are briefly mentioned.

Proteomic analysis of menstrual blood

Menstruation is the expulsion of the endometrial lining of the uterus following a nearly month long preparation for embryo implantation and pregnancy. Increasingly, the health of the endometrium is being recognized as a critical factor in female fertility, and proteomes and transcriptomes from endometrial biopsies at different stages of the menstrual cycle have been studied for both diagnostic and therapeutic purposes (1 Kao, L. C., et al. 2003 Endocrinology 144, 2870-2881; Strowitzki, Tet al. 2006 Hum. Reprod. Update 12, 617-630; DeSouza, L., et al. 2005 Proteomics 5, 270-281). Disorders of the uterus ranging from benign to malignant tumors, as well as endometriosis, can cause abnormal menstrual bleeding and are frequently diagnosed through endometrial biopsy (Strowitzki, Tet al. 2006 Hum. Reprod. Update 12, 617-630; Ferenczy, A. 2003 Maturitas 45, 1-14). Yet the proteome of menstrual blood, an easily available noninvasive source of endometrial tissue, has yet to be examined for possible causes or diagnoses of infertility or endometrial pathology. This study employed five different methods to define the menstrual blood proteome. A total of 1061 proteins were identified, 361 were found by at least two methods and 678 were identified by at least two peptides. When the menstrual blood proteome was compared with those of circulating blood (1774 proteins) and vaginal fluid (823 proteins), 385 proteins were found unique to menstrual blood. Gene ontology analysis and evaluation of these specific menstrual blood proteins identified pathways consistent with the processes of the normal endometrial cycle. Several of the proteins unique to menstrual blood suggest that extramedullary uterine hematopoiesis or parenchymal hemoglobin synthesis may be occurring in late endometrial tissue. The establishment of a normal menstrual blood proteome is necessary for the evaluation of its usefulness as a diagnostic tool for infertility and uterine pathologies. Identification of unique menstrual blood proteins should aid the forensic community in distinguishing menstrual blood from circulating blood.

Selective impact of HIV disease progression on the innate immune system in the human female reproductive tract

BACKGROUND

We have previously demonstrated intrinsic anti-HIV activity in cervicovaginal lavage (CVL) from HIV-infected women with high CD4 counts and not on antiretroviral therapy. However, the impact of HIV disease progression on CVL innate immune responses has not been delineated.

METHODS

CVL from 57 HIV-infected women not on antiretroviral therapy were collected by washing the cervicovaginal area with 10 ml of sterile normal saline. We characterized subject HIV disease progression by CD4 count strata: >500 cells/µl, 200-500 cells/µl, or <200 cells/µl of blood. To assess CVL anti-HIV activity, we incubated TZM-bl cells with HIV plus or minus CVL. Antimicrobials, cytokines, chemokines and anti-gp160 HIV IgG antibodies were measured by ELISA and Luminex.

RESULTS

CVL exhibited broad anti-HIV activity against multiple laboratory-adapted and transmitted/founder (T/F) viruses, with anti-HIV activity ranging from 0 to 100% showing wide variation between viral strains. Although there was broad CVL inhibition of most both laboratory-adapted and T/F virus strains, there was practically no inhibition of T/F strain RHPA.c, which was isolated from a woman newly infected via heterosexual intercourse. HIV disease progression, measured by declining CD4 T cell counts, resulted in a selective reduction in intrinsic anti-HIV activity in CVL that paralleled CVL decreases in human beta-defensin 2 and increases in Elafin and secretory leukocyte protease inhibitor. HIV disease progress predicted decreased CVL anti-HIV activity against both laboratory-adapted and T/F strains of HIV. Anti-HIV activity exhibited close associations with CVL levels of fourteen cytokines and chemokines.

CONCLUSIONS

Amid a multifaceted immune defense against HIV-1 and other sexually transmitted pathogens, HIV disease progression is associated with selective disturbances in both CVL anti-HIV activity and specific innate immune defenses in the human female reproductive tract (FRT). Overall, these studies indicate that innate immune protection in the FRT is compromised as women progress to AIDS.

Lactoferrin: an alternative view of its role in human biological fluids

Lactoferrin is a major component of biologically important mucosal fluids and of the specific granules of neutrophils. Understanding its biological function is essential for understanding neutrophil- and mucosal-mediated immunity. In this review, we reevaluate the in vivo functions of human lactoferrin (hLF) emphasizing in vivo studies and in vitro studies performed in biologically relevant fluids. We discuss the evidence in the literature that supports (or does not support) proposed roles for hLF in mucosal immunity and in neutrophil function. We argue that the current literature supports a microbiostatic role, but not a microbicidal role, for hLF in vivo. The literature also supports a role for hLF in inhibiting colonization and infection of epithelial surfaces by microorganisms and in protecting tissues from neutrophil-mediated damage. Using this information, we briefly discuss hLF in the context of the complex biological fluids in which it is found.

Profiling cervical lavage fluid by SELDI-TOF mass spectrometry

The mucosal surface of the female genital tract is the first site of contact for many sexually transmitted infections and serves as the first layer of defense. This layer has components of both the innate and adaptive immune systems to protect against infections. For these reasons, this fluid is a major focus of study to understand the pathogenesis of different infectious diseases. Novel tools are available to allow for the analysis of the components of this mucosal layer, including the area of proteomics. The emergence of proteomics has allowed for the development of many types of platforms for protein profiling, including gel-based technologies (2-dimensional differential in-gel electrophoresis) and mass spectrometry-based techniques. SELDI-TOF, a mass spectrometry-based platform coupled to on-chip chromatographic separation, has been developed as a high-throughput technique to profile complex protein samples. This chapter will outline detailed methods to profile cervical mucosal samples by SELDI-TOF and can serve as a guideline for other types of mucosal samples.

HIV-neutralizing activity of cationic polypeptides in cervicovaginal secretions of women in HIV-serodiscordant relationships

Background

HIV exposed seronegative (HESN) women represent the population most in need of a prophylactic antiviral strategy. Mucosal cationic polypeptides can potentially be regulated for this purpose and we here aimed to determine their endogenous expression and HIV neutralizing activity in genital secretions of women at risk of HIV infection.

Methodology/Principal Findings

Cervicovaginal secretions (CVS) of Kenyan women in HIV-serodiscordant relationships (HESN, n = 164; HIV seropositive, n = 60) and low-risk controls (n = 72) were assessed for the cationic polypeptides HNP1–3, LL-37 and SLPI by ELISA and for HIV neutralizing activity by a PBMC-based assay using an HIV primary isolate. Median levels of HNP1–3 and LL-37 in CVS were similar across study groups. Neither HSV-2 serostatus, nor presence of bacterial vaginosis, correlated with levels of HNP1–3 or LL-37 in the HESN women. However, an association with their partner's viral load was observed. High viral load (>10,000 HIV RNA copies/ml plasma) correlated with higher levels of HNP1–3 and LL-37 (p = 0.04 and 0.03, respectively). SLPI was most abundant in the low-risk group and did not correlate with male partner's viral load in the HESN women. HIV neutralizing activity was found in CVS of all study groups. In experimental studies, selective depletion of cationic polypeptides from CVS rendered the remaining CVS fraction non-neutralizing, whereas the cationic polypeptide fraction retained the activity. Furthermore, recombinant HNP1–3 and LL-37 could induce neutralizing activity when added to CVS lacking intrinsic activity.

Conclusions/Significance

These findings show that CVS from HESN, low-risk, and HIV seropositive women contain HIV neutralizing activity. Although several innate immune proteins, including HNP1–3 and LL-37, contribute to this activity these molecules can also have inflammatory properties. This balance is influenced by hormonal and environmental factors and in the present HIV serodiscordant couple cohort study we show that a partner's viral load is associated with levels of such molecules.

Anti-HIV-1 activity of elafin is more potent than its precursor's, trappin-2, in genital epithelial cells

Cervicovaginal lavage fluid (CVL) is a natural source of anti-HIV-1 factors; however, molecular characterization of the anti-HIV-1 activity of CVL remains elusive. In this study, we confirmed that CVLs from HIV-1-resistant (HIV-R) compared to HIV-1-susceptible (HIV-S) commercial sex workers (CSWs) contain significantly larger amounts of serine antiprotease trappin-2 (Tr) and its processed form, elafin (E). We assessed anti-HIV-1 activity of CVLs of CSWs and recombinant E and Tr on genital epithelial cells (ECs) that possess (TZM-bl) or lack (HEC-1A) canonical HIV-1 receptors. Our results showed that immunodepletion of 30% of Tr/E from CVL accounted for up to 60% of total anti-HIV-1 activity of CVL. Knockdown of endogenous Tr/E in HEC-1A cells resulted in significantly increased shedding of infectious R5 and X4 HIV-1. Pretreatment of R5, but not X4 HIV-1, with either Tr or E led to inhibition of HIV-1 infection of TZM-bl cells. Interestingly, when either HIV-1 or cells lacking canonical HIV-1 receptors were pretreated with Tr or E, HIV-1 attachment and transcytosis were significantly reduced, and decreased attachment was not associated with altered expression of syndecan-1 or CXCR4. Determination of 50% inhibitory concentrations (IC(50)) of Tr and E anti-HIV-1 activity indicated that E is ∼130 times more potent than its precursor, Tr, despite their equipotent antiprotease activities. This study provides the first experimental evidence that (i) Tr and E are among the principal anti-HIV-1 molecules of CVL; (ii) Tr and E affect cell attachment and transcytosis of HIV-1; (iii) E is more efficient than Tr regarding anti-HIV-1 activity; and (iv) the anti-HIV-1 effect of Tr and E is contextual.

Infection by CXCR4-Tropic Human Immunodeficiency Virus Type 1 Is Inhibited by the Cationic Cell-Penetrating Peptide Derived from HIV-1 Tat

Cell-penetrating peptides (CPP), which are short peptides that are capable of crossing the plasma membrane of a living cell, are under development as delivery vehicles for therapeutic agents that cannot themselves enter the cell. One well-studied CPP is the 10-amino acid peptide derived from the human immunodeficiency virus type 1 (HIV-1) Tat protein. In experiments to test the hypothesis that multiple cationic amino acids within Tat peptide confer antiviral activity against HIV-1, introduction of Tat peptide resulted in concentration-dependent inhibition of HIV-1 IIIB infection. Using Tat peptide variants containing arginine substitutions for two nonionic residues and two lysine residues, HIV-1 inhibition experiments demonstrated a direct relationship between cationic charge and antiviral potency. These studies of Tat peptide as an antiviral agent raise new questions about the role of Tat in HIV-1 replication and provide a starting point for the development of CPPs as novel HIV-1 inhibitors.

War and peace between WAP and HIV: role of SLPI, trappin-2, elafin and ps20 in susceptibility to HIV infection

Despite tremendous advances in our understanding of HIV/AIDS since the first cases were reported 30 years ago, we are still a long way from understanding critical steps of HIV acquisition, pathogenesis and correlates of protection. Our new understanding of the importance of the mucosa as a target for HIV infection, as well as our recent observations showing that altered expression and responses of innate pattern recognition receptors are significantly associated with pathogenesis and resistance to HIV infection, indicate that correlates of immunity to HIV are more likely to be associated with mucosal and innate responses. Most of the heterosexual encounters do not result in productive HIV infection, suggesting that the female genital tract is protected against HIV by innate defence molecules, such as antiproteases, secreted mucosally. The present review highlights the role and significance of the serine protease inhibitors SLPI (secretory leucocyte protease inhibitor), trappin-2, elafin and ps20 (prostate stromal protein 20 kDa) in HIV susceptibility and infection. Interestingly, in contrast with SLPI, trappin-2 and elafin, ps20 has been shown to enhance HIV infectivity. Thus understanding the balance and interaction of these factors in mucosal fluids may significantly influence HIV infection.

Comprehensive proteomic study identifies serpin and cystatin antiproteases as novel correlates of HIV-1 resistance in the cervicovaginal mucosa of female sex workers

Not all individuals exposed to HIV-1 become infected, and evidence from HIV-1 highly exposed seronegative women (HIV-1-resistant) suggests that mucosal factors in the female genital tract, the first site of contact for the virus, are playing a role. To better understand factors mediating protection from HIV-1, we performed a large clinical study using the tools of systems biology to fully characterize the cervicovaginal mucosa proteome in HIV-1-resistant women. Cervicovaginal lavage fluid was collected from 293 HIV-1-resistant, uninfected, and infected sex workers and analyzed by 2D-LC LTQ-FT-MS. Of the more than 360 unique proteins identified, 41 were differentially abundant (>3-fold cutoff) in HIV-1-resistant women. The majority of over-abundant proteins were antiproteases (>40%), some with described anti-inflammatory and anti-HIV-1 activity. Quantification of specific anti-HIV-1 antiproteases Serpin A1, Serpin A3, and Cystatin B and an epithelial antiprotease A2ML1 found them to be significantly over-abundant in HIV-1-resistant women (p = 0.004; p = 0.046; p = 0.0003; and p = 0.04, respectively). Expression levels were not correlated to sexual practices or other epidemiological factors. Mucosal antiprotease levels correlated with pro-inflammatory cytokine concentration (p = <0.0001), but independently of pro-inflammatory cytokine levels in HIV-1-resistant women including TNF-alpha, IL-1 alpha, IL-1 beta, IL-6, and IL-8. This comprehensive systems biology approach identifies mucosal serpins and cystatins as novel correlates of HIV-1-resistance. This represents the first study characterizing these factors in the female genital tract.

Innate immunity in the human female reproductive tract: endocrine regulation of endogenous antimicrobial protection against HIV and other sexually transmitted infections

Mucosal surfaces of the female reproductive tract (FRT) contain a spectrum of antimicrobials that provide the first line of defense against viruses, bacteria, and fungi that enter the lower FRT. Once thought to be a sterile compartment, the upper FRT is periodically exposed to pathogens throughout the menstrual cycle. More recently, secretions from the upper FRT have been shown to contribute to downstream protection in the lower FRT. In this review, we examine the antimicrobials in FRT secretions made by immune cells and epithelial cells in the upper and lower FRT that contribute to innate protection. Because each site is hormonally regulated to maintain fertility, this review focuses on the contributions of hormone balance during the menstrual cycle to innate immune protection. As presented in this review, studies from our laboratory and others demonstrate that sex hormones regulate antimicrobials produced by innate immune cells throughout the FRT. The goal of this review is to examine the spectrum of antimicrobials in the FRT and the ways in which they are regulated to provide protection against pathogens that compromise reproductive health and threaten the lives of 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.

Characterization of the retrocyclin analogue RC-101 as a preventative of Staphylococcus aureus nasal colonization

Nasal colonization of Staphylococcus aureus is a risk factor for pathogenic autoinfection, particularly in postoperative patients and the immunocompromised. As such, standardized preoperative nasal decolonization of S. aureus has become a major consideration for the prevention of nosocomial infection. However, only a few treatment options for nasal decolonization are currently available, with resistance to these approaches already a concern. Here we have identified the macrocyclic -defensin analogue RC-101 as a promising anti-S. aureus agent for nasal decolonization. RC-101 exhibits bactericidal effects against S. aureus with the use of in vitro epithelium-free systems, while also preventing the pathogen's proliferation and attachment in an ex vivo human nasal epithelial cell adhesion model and an organotypic model of human airway epithelia. Peptide concentrations as low as 2.5 μM elicited significant reductions in S. aureus growth in epithelium-free systems, with 10 μM concentrations being completely bactericidal for all strains tested, including USA300. In ex vivo nasal colonization models, RC-101 significantly reduced adherence, survival, and proliferation of S. aureus on human nasal epithelia. Reductions in S. aureus viability were evident in these assays, with as little as 1 μg of peptide per tissue, while 10 μg of RC-101 completely prevented adhesion of all strains tested. Furthermore, RC-101 did not exhibit cellular toxicity to human nasal epithelia at concentrations up to 200 μM, nor did it induce a proinflammatory response in these cells. Collectively, the findings of this study identify RC-101 as a potential preventative of S. aureus nasal colonization.

Cystatin A protease inhibitor and cysteine proteases in human cervicovaginal fluid in term pregnancy and labor

OBJECTIVE

The purpose of this study was to investigate the temporal changes in immunoreactive cystatin A and the enzymatic activity of cathepsins B, H, L, and S in human cervicovaginal fluid (CVF) in late pregnancy and spontaneous labor.

STUDY DESIGN

CVF was collected weekly (n = 95 women) from 36 weeks gestation until spontaneous term labor. Cystatin A was quantified using enzyme-linked immunosorbent assay. The enzyme activity of cathepsins B, H, L, and S was measured with fluorometric enzyme assay kits.

RESULTS

Cystatin A significantly decreased towards (P = .016, 2-way analysis of variance) and during labor (P < .001, 2-way analysis of variance). Enzymatic activity of cathepsins B, H, and S did not change with labor onset (P = .452, P = .703, P = .411, respectively, 2-way analysis of variance).

CONCLUSION

In late gestation, CVF-decreased expression of the cysteine protease inhibitor, cystatin A, is associated with labor. Although the role and contribution of cystatin A to increased extracellular matrix remodeling has yet to be elucidated, the data that were obtained are consistent with this hypothesis.

A randomized trial to assess anti-HIV activity in female genital tract secretions and soluble mucosal immunity following application of 1% tenofovir gel

Background

Preclinical and early phase clinical microbicide studies have not consistently predicted the outcome of efficacy trials. To address this gap, candidate biomarkers of microbicide pharmacodynamics and safety were evaluated in a double-blind, placebo-controlled trial of tenofovir gel, the first microbicide to demonstrate significant protection against HIV acquisition.

Methods

30 women were randomized to apply a single daily dose of tenofovir or placebo gel for 14 consecutive days. Anti-HIV activity was measured in cervicovaginal lavage (CVL) on Days 0, 3, 7, 14 and 21 by luciferase assay as a surrogate marker of pharmacodynamics. Endogenous activity against E. coli and HSV-2 and concentrations of immune mediators were quantified in CVL as candidate biomarkers of safety. Tenofovir levels were measured in CVL and blood.

Results

A significant increase in anti-HIV activity was detected in CVL from women who applied tenofovir gel compared to their endogenous anti-HIV activity in genital tract secretions on Day 0 and compared to activity in CVL from women in the placebo group. The activity correlated significantly with CVL concentration of tenofovir (r = 0.6, p<0.001) and fit a sigmoid E_max pharmacodynamic model. Anti-HIV activity in CVL from women who applied tenofovir persisted when virus was introduced in semen, whereas endogenous anti-HIV activity decreased. Tenofovir did not trigger an inflammatory response or induce sustained loss in endogenous antimicrobial activity or immune mediators.

Conclusions

Tenofovir gel had no deleterious impact on soluble mucosal immunity. The increased anti-HIV activity in CVL, which persisted in the presence of semen and correlated with tenofovir concentration, is consistent with the efficacy observed in a recent clinical trial. These results promote quantified CVL anti-HIV activity as a surrogate of tissue pharmacodynamics and as a potential biomarker of adherence to product. This simple, feasible and inexpensive bioassay may promote the development of models more predictive of microbicide efficacy.

Trial Registration

ClinicalTrials.gov NCT00594373

Antibacterial activity of a synthetic peptide that mimics the LPS binding domain of Indian mud crab, Scylla serrata anti-lipopolysaccharide factor (SsALF) also involved in the modulation of vaginal immune functions through NF-kB signaling

Recently the cDNA coding for anti-lipopolysaccharide factor (ALF) has been identified from the Indian mud crab, Scylla serrata and has been named S. serrata anti-lipopolysaccharide factor (SsALF). SsALF protein sequence demonstrated the presence of two highly conserved cystine residues between which the putative lipopolysaccharide (LPS) binding domain is known to be located. In this study, we have designed and synthesized a 24 amino acid linear (lSsALF24) and a cyclic (cSsALF24) peptides based on this putative LPS binding domain and demonstrated the ability of these peptides to bind to LPS. The peptides were active against vaginal pathogens demonstrated by MIC, CFU and phagocytosis assays. cSsALF24 did not show toxicity to human vaginal epithelial cells (HeLa-S3), macrophages and rabbit erythrocytes even at high concentration (64.64 μM). Flow cytometry results demonstrated that cSsALF24 peptide suppressed LPS induced phagocytosis of FITC labeled E. coli. HeLa cells were stimulated with LPS (10 μg/ml) alone for 6 h or after two washings with PBS, treated for 1 h with cSsALF24 (64.64 μM). After washing, the cells were cultured for 24 h in fresh media. The spent media as well as cells were collected for the determination of cytokine/chemokine levels such as interleukin-6 (IL-6) interleukin-8 (IL-8), monocyte chemotactic protein-1 (MCP-1) and interleukin-1α (IL-1α) using ELISA and RT-PCR respectively. Similar results were obtained with LPS stimulated cells treated with c/nSsALF24 or unstimulated cells treated with c/nSsALF24. The expression of cytokine/chemokines and mRNA's coding these proteins were unaffected in c/nSsALF24 treated cells. In contrast, in LPS stimulated cells, the expression levels of these molecules were up-regulated via the induction of nuclear factor kappa-B (NF-kB) levels. However, the expression of these pro-inflammatory markers was decreased in LPS stimulated cells following the treatment with cSsALF24, attributing anti-inflammatory potential of the peptide. Collectively, these findings suggest that cSsALF24 might regulate the vaginal epithelial cell immune responses indirectly through modulation of LPS-TLR4 binding in NF-kB pathway.

Female genital tract secretions and semen impact the development of microbicides for the prevention of HIV and other sexually transmitted infections

Pharmacologic strategies for the prevention of HIV include vaccines, post-exposure prophylaxis with antiretroviral therapy, and topical microbicides. Vaginal microbicides have the potential to augment innate defenses in the genital tract but may also disrupt endogenous protection and increase HIV acquisition risk, as observed in clinical trials of nonoxynol-9. The initially disappointing results of microbicide clinical trials stimulated the development of more sensitive and comprehensive pre-clinical safety studies, which include dual-chamber culture systems to model the epithelial barrier and post-coital studies to evaluate the effects of semen and sexual intercourse on microbicide efficacy. This review discusses the key factors that contribute to a healthy female genital tract environment, the impact of semen on mucosal defense, and how our understanding of these mediators informs the development of effective vaginal microbicides.

Use of cervicovaginal fluid for the identification of biomarkers for pathologies of the female genital tract

Cervicovaginal fluid has an important function in the homeostasis and immunity of the lower female genital tract. Analysis of the cervicovaginal fluid proteome may therefore yield important information about the pathogenesis of numerous gynecological pathologies. Additionally, cervicovaginal fluid has great potential as a source of biomarkers for these conditions.

This review provides a detailed discussion about the human cervicovaginal proteome and the proteomics studies performed to characterize this biological fluid. Furthermore, infection-correlated pathological conditions of the female genital tract are discussed for which cervicovaginal fluid has been used in order to identify potential biomarkers. Recent years, numerous studies have analyzed cervicovaginal fluid samples utilizing antibody-based technologies, such as ELISA or Western blotting, to identify biomarkers for preterm birth, premature preterm rupture of membranes, bacterial vaginosis and cervical cancer. The present article will discuss the importance of proteomic technologies as alternative techniques to gain additional meaningful information about these conditions. In addition, the review focuses on recent proteomic studies on cervicovaginal fluid samples for the identification of potential biomarkers. We conclude that the use of proteomic technology for analysis of human cervicovaginal fluid samples is promising and may lead to the discovery of new biomarkers which can improve disease prevention and therapy development.

Psoriasin (S100A7) is a major Escherichia coli-cidal factor of the female genital tract

The female urogenital tract requires an efficient defense against bacteria, potentially derived from the adjacent intestinal tract. We have thus sought to identify the factors that protect against Escherichia coli (E. coli) in the female genital tract. Vaginal fluid from healthy human donors consistently killed E. coli in vitro and vaginal epithelium strongly expressed and secreted psoriasin. Psoriasin was constitutively produced in an organotypic vaginal epithelium model, and exposure of these cells to supernatants of E. coli cultures led to an enhanced psoriasin expression. Secreted psoriasin in vaginal fluids accounted for approximately 2.5-3% of total protein. Fractionation of vaginal fluids by high performance liquid chromatography (HPLC) showed that psoriasin co-eluted with a peak of E. coli killing activity. Our data show that normal vaginal fluid contains a powerful intrinsic antimicrobial defense against E. coli and that psoriasin contributes to the innate immune response of the female genital tract.

In vivo evaluation of the release of zidovudine and polystyrene sulfonate from a dual intravaginal bioadhesive polymeric device in the pig model

This study focused on determining the concentration of zidovudine (AZT) and polystyrene sulfonate (PSS) in the plasma and vaginal tissue of the large white pig from an intravaginal bioadhesive polymeric device (IBPD). Biocompatible polymers were compressed with AZT and PSS into caplet-shaped devices for insertion into the posterior fornix of the pig vagina. A total of 25 pigs were used in this study. Plasma was sampled from the jugular vein at various time points after insertion of the IBPD reaching 28 days. At day 28, the pigs were euthanized and vaginal tissue was removed and digested with subtilisin for AZT and PSS extraction. The mean concentration detected in vaginal tissue at day 28 was 1.214 ± 0.062 mg/mL for AZT and 1.400 ± 0.071 mg/mL for PSS. Plasma concentration was significantly lower for AZT (0.332 ± 0.014 mg/mL) and PSS (0.256 ± 0.013 mg/mL). This indicated higher retention of AZT and PSS within the vaginal tissue. Molecular mechanics simulations blueprinted polymer-drug-mucin force-field interactions and energies that explicated the spatial preference of AZT and PSS for the vaginal tissue. Histopathotoxicity studies revealed negative-to-mild foreign body events and results strongly suggest that the IBPD may be suitable for prolonged intravaginal drug delivery in preventing the transmission of sexually transmitted infections and HIV/AIDS.

Development of an in vitro alternative assay method for vaginal irritation

The vaginal mucosa is commonly exposed to chemicals and therapeutic agents that may result in irritation and/or inflammation. In addition to acute effects, vaginal irritation and inflammation can make women more susceptible to infections such as HIV-1 and herpes simplex virus 2 (HSV-2). Hence, the vaginal irritation potential of feminine care formulations and vaginally administered therapeutic agents is a significant public health concern. Traditionally, testing of such materials has been performed using the rabbit vaginal irritation (RVI) assay. In the current study, we investigated whether the organotypic, highly differentiated EpiVaginal™ tissue could be used as a non-animal alternative to the RVI test. The EpiVaginal tissue was exposed to a single application of ingredients commonly found in feminine hygiene products and the effects on tissue viability (MTT assay), barrier disruption (measured by transepithelial electrical resistance, TEER and sodium fluorescein (NaFl) leakage), and inflammatory cytokine release (interleukin (IL)-1α, IL-1β, IL-6, and IL-8) patterns were examined. When compared to untreated controls, two irritating ingredients, nonoxynol 9 and benzalkonium chloride, reduced tissue viability to <40% and TEER to <60% while increasing NaFl leakage by 11-24% and IL-1α and IL-1β release by >100%. Four other non-irritating materials had minimal effects on these parameters. Assay reproducibility was confirmed by testing the chemicals using three different tissue production lots and by using tissues reconstructed from cells obtained from three different donors. Coefficients of variation between tissue lots reconstructed with cells obtained from the same donor or lots reconstructed with cells obtained from different donors were less than 10% and 12%, respectively. In conclusion, decreases in tissue viability and barrier function and increases in IL-1α and IL-1β release appear to be useful endpoints for preclinical screening of topically applied chemicals and formulations for their vaginal irritation potential.

Identification and characterization of anti-microbial peptides from rabbit vaginal fluid

Antimicrobial peptides (AMPs) serve as a first line of host defense and represent an important, though poorly understood components of the innate immune system. The present study was an attempt to identify and characterize the major molecules having anti-bacterial activities from the vaginal fluid of rabbit, Oryctologus cuniculus. AMPs from the rabbit vaginal fluid (RVF) were identified in the acid extracts of pooled RVF samples after RP-HPLC purification. The protein, RVFAMP was effective against gram negative (Escherichia coli and Pseudomonas aeruginosa) and gram positive (Staphylococcus aureus and Streptococcus pyogenes) bacteria. The results of acid urea-PAGE-gel overlay assay (AU-PAGE-GOA) demonstrated clear zone of growth inhibition of E. coli corresponding to 6 and 15 kDa protein bands. LC-MS data of these proteins indicated that 15 kDa protein consists of lysozyme, lipopolysaccharide binding protein (LBP), hemoglobin-α and β subunits (Hb-α/β), whereas 9 kDa protein band consists of transthyretin and calcyclin while uteroglobulin and neutrophil antibacterial peptide-5 (NAMP-5) are present in the 6 kDa protein band. Of the eight proteins, Hb-α derived protein was further characterized, as it showed the highest Probability Based Mowse Score (PBMS) of 288. A 25mer peptide, RVFHbαp was active against several clinical pathogens as demonstrated by minimum inhibitory concentration (MIC) and radial diffusion assays (RDA). The interaction of RVFHbαP with bacterial liposome membrane was assessed by calcein dye leakage assay. RVFHbαP did not show cytotoxicity against human endocervical cells (End1/E6E7) or erythrocytes. RT-PCR and immunofluorescence results revealed the expression of RVFHbαP mRNA and protein in rabbit vaginal tissue. To the best our knowledge, this is the first report describing the detection of AMPs in RVFs. In conclusion, these studies indicated that vaginal epithelial cells (VEC) derived RVFHbαP may have therapeutic potential in the management of reproductive well being of rabbits. The major reason for undertaking this study in rabbits is that, it forms an excellent in vivo model system for human's studies.

Amyloid-binding small molecules efficiently block SEVI (semen-derived enhancer of virus infection)- and semen-mediated enhancement of HIV-1 infection

Semen was recently shown to contain amyloid fibrils formed from a self-assembling peptide fragment of the protein prostatic acid phosphatase. These amyloid fibrils, termed semen-derived enhancer of virus infection, or SEVI, have been shown to strongly enhance HIV infectivity and may play an important role in sexual transmission of HIV, making them a potential microbicide target. One novel approach to target these fibrils is the use of small molecules known to intercalate into the structure of amyloid fibrils, such as derivatives of thioflavin-T. Here, we show that the amyloid-binding small molecule BTA-EG₆ (the hexa(ethylene glycol) derivative of benzothiazole aniline) is able to bind SEVI fibrils and effectively inhibit both SEVI-mediated and semen-mediated enhancement of HIV infection. BTA-EG₆ also blocks the interactions of SEVI with HIV-1 virions and HIV-1 target cells but does not cause any inflammation or toxicity to cervical epithelial cells. These results suggest that an amyloid-binding small molecule may have utility as a microbicide, or microbicidal supplement, for HIV-1.

A review of the critical role of vitamin D in the functioning of the immune system and the clinical implications of vitamin D deficiency

This review looks at the critical role of vitamin D in improving barrier function, production of antimicrobial peptides including cathelicidin and some defensins, and immune modulation. The function of vitamin D in the innate immune system and in the epithelial cells of the oral cavity, lung, gastrointestinal system, genito-urinary system, skin and surface of the eye is discussed. Clinical conditions are reviewed where vitamin D may play a role in the prevention of infections or where it may be used as primary or adjuvant treatment for viral, bacterial and fungal infections. Several conditions such as tuberculosis, psoriasis, eczema, Crohn's disease, chest infections, wound infections, influenza, urinary tract infections, eye infections and wound healing may benefit from adequate circulating 25(OH)D as substrate. Clinical diseases are presented in which optimization of 25(OH)D levels may benefit or cause harm according to present day knowledge. The safety of using larger doses of vitamin D in various clinical settings is discussed.

Systems biology-based approaches to understand HIV-exposed uninfected women

Worldwide HIV infects women more frequently than men, and it is clear that not all exposed to HIV become infected. Several populations of HIV-exposed uninfected (EU) women have been identified, including discordant couples and sex workers. Understanding what provides natural protection in EU women is critical in vaccine or microbicide development. However, correlates of protection in these women are still unclear. Most studies have used classical methods, examining single genes or cellular factors, a mainstay for traditional immunobiology. This reductionist approach may be limited in the information it can provide. Novel technologies are now available that allow us to take a "systems biology" approach, which allows the study of a complex biological system and identifies factors that may provide protection against HIV infection. Herein we report developments in discovery-based systems biology approaches in EU women and how this broadens our understanding of natural protection against HIV-1.

Effect of the antimicrobial peptide tritrpticin on the in vitro viability and growth of Trichomonas vaginalis

Antimicrobial peptides are widely distributed in nature; they play important roles in several aspects of innate immunity and may provide a basis for the design of novel therapeutic agents. In this study, C-amidated tritrpticin, a 13 amino acid tryptophan-rich antimicrobial peptide derived from a porcine cathelicidin, was tested against Trichomonas vaginalis, a protozoan that causes a serious non-viral sexually transmitted disease associated with preterm birth, low birth weight, and high risk of HIV-1 infection. Tritrpticin was selected due to its reasonably easy synthesis and because analogs with lower toxicity may be designed. Our results show that tritrpticin-NH(2) at either 100 or 200 μg/ml (52.5 or 105 μM) clearly reduces the viability and growth of Trichomonas vaginalis. Together with tritrpticin-NH(2), sodium bicarbonate further limited trichomonad growth. Additionally, a low concentration of metronidazole (5.8 μM), the most commonly used medication for Trichomonas vaginalis, was more effective against the growth of the parasite when it was combined with tritrpticin-NH(2).

Anti-HIV activity in cervical-vaginal secretions from HIV-positive and -negative women correlate with innate antimicrobial levels and IgG antibodies

Background

We investigated the impact of antimicrobials in cervicovaginal lavage (CVL) from HIV(+) and HIV(−) women on target cell infection with HIV. Since female reproductive tract (FRT) secretions contain a spectrum of antimicrobials, we hypothesized that CVL from healthy HIV(+) and (−) women inhibit HIV infection.

Methodology/Principal Findings

CVL from 32 HIV(+) healthy women with high CD4 counts and 15 healthy HIV(−) women were collected by gently washing the cervicovaginal area with 10 ml of sterile normal saline. Following centrifugation, anti-HIV activity in CVL was determined by incubating CVL with HIV prior to addition to TZM-bl cells. Antimicrobials and anti-gp160 HIV IgG antibodies were measured by ELISA. When CXCR4 and CCR5 tropic HIV-1 were incubated with CVL from HIV(+) women prior to addition to TZM-bl cells, anti-HIV activity in CVL ranged from none to 100% inhibition depending on the viral strains used. CVL from HIV(−) controls showed comparable anti-HIV activity. Analysis of CH077.c (clone of an R5-tropic, mucosally-transmitted founder virus) viral inhibition by CVL was comparable to laboratory strains. Measurement of CVL for antimicrobials HBD2, trappin-2/elafin, SLPI and MIP3α indicated that each was present in CVL from HIV(+) and HIV(−) women. HBD2 and MIP3α correlated with anti-HIV activity as did anti-gp160 HIV IgG antibodies in CVL from HIV(+) women.

Conclusions/Significance

These findings indicate that CVL from healthy HIV(+) and HIV(−) women contain innate and adaptive defense mechanisms that inhibit HIV infection. Our data suggest that innate endogenous antimicrobials and HIV-specific IgG in the FRT can act in concert to contribute toward the anti-HIV activity of the CVL and may play a role in inhibition of HIV transmission to women.

Postcoital bioavailability and antiviral activity of 0.5% PRO 2000 gel: implications for future microbicide clinical trials

Background

The pharmacokinetics and pharmacodynamics of vaginal microbicides are typically assessed among sexually abstinent women. However, the physical act of sex may modulate gel distribution, and preclinical studies demonstrate seminal plasma interferes with the antiviral activity of several microbicides. This study compared the biological activity and concentration of PRO 2000 in cervicovaginal lavage (CVL) collected in the absence or following coitus.

Methods

CVL samples were collected from ten heterosexual couples at baseline, after sex, after a single dose of 0.5% PRO 2000 gel and sex, and after gel application without sex. The impact of CVL on HIV-1 infection of TZM-bl cells and HSV-2 infection of CaSki cells was monitored by luciferase and plaque assay, respectively. PRO 2000 concentrations were measured by fluorescence.

Results

CVL collected after PRO 2000 application significantly inhibited HIV-1 and HSV-2 (p = 0.01). However, the antiviral activity was reduced following sex and no significant protective effect was observed in postcoital CVL obtained in the presence compared to the absence of PRO 2000 for HIV (p = 0.45) or HSV-2 (p = 0.56). Less PRO 2000 was recovered in postcoital CVL, which, in conjunction with interference by seminal plasma, may have contributed to lower antiviral activity.

Conclusions

Postcoital responses to PRO 2000 differ from precoital measures and the results obtained may provide insights into the clinical trial findings in which there was no significant protection against HIV-1 or HSV-2. Postcoital studies should be incorporated into clinical studies before embarking on large-scale efficacy trials.

Human defensins and LL-37 in mucosal immunity

Defensins are widespread in nature and have activity against a broad range of pathogens. Defensins have direct antimicrobial effects and also modulate innate and adaptive immune responses. We consider the role of human defensins and the cathelicidin LL-37 in defense of respiratory, gastrointestinal, and genitourinary tracts and the oral cavity, skin, and eye. Human beta-defensins (hBDs) and human defensins 5 and 6 (HD5 and -6) are involved most obviously in mucosal responses, as they are produced principally by epithelial cells. Human alpha-defensins 1-4 (or HNPs 1-4) are produced principally by neutrophils recruited to the mucosa. Understanding the biology of defensins and LL-37 is the beginning to clarify the pathophysiology of mucosal inflammatory and infectious diseases (e.g., Crohn's disease, atopic dermatitis, lung or urinary infections). Challenges for these studies are the redundancy of innate defense mechanisms and the presence and interactions of many innate defense proteins in mucosal secretions.

Mucosal immunity to HIV: a review of recent literature

PURPOSE OF REVIEW

This review summarizes recent literature in the field of mucosal immunology as it applies to HIV transmission and pathogenesis.

RECENT FINDINGS

Pertinent recent findings include elucidation of the role of mucosal antigen-presenting cells and retinoic acid in imprinting a gut-homing phenotype on antigen-specific T and B cells, and the identification of Th17 and T regulatory cells as key modulators of the balance between tolerance and inflammation in mucosal tissues.

SUMMARY

Mucosal surfaces of the body serve as the major portal of entry for HIV. These tissues also house a majority of the body's lymphocytes, including the CD4 T-cells that are the major cellular target for HIV infection. Elucidating mucosal immune responses is critical to our understanding of the host-pathogen relationship for two reasons: first, mucosal barriers are defended by a range of innate and adaptive defenses that might be exploited to develop effective vaccines or microbicides; second, adaptive immune responses in mucosal lymphoid tissues might serve to limit viral replication, decreasing the host's viral burden as well as reducing the likelihood of sexual transmission to a naïve host.

CCL20/MIP3alpha is a novel anti-HIV-1 molecule of the human female reproductive tract

PROBLEM

CCL20/MIP3alpha is a chemokine for immature dendritic cells as well as an antibacterial against gram-positive and gram-negative bacteria. The role of CCL20/MIP3alpha as an antiviral is unknown. In this study, we have examined the production of CCL20/MIP3alpha by epithelial cells from the upper female reproductive tract as well as its activity as an antiviral molecule.

METHOD OF STUDY

Primary uterine and Fallopian tube epithelial cells were treated with Poly(I:C) and CCL20/MIP3alpha mRNA and protein was measured by Realtime RT-PCR and ELISA assays. Anti-HIV activity was determined using an indicator cell line TZM-bl and quantified by using a luminometer.

RESULTS

Primary uterine and Fallopian tube epithelial cells produce CCL20/MIP3alpha constitutively and the production is enhanced following stimulation with viral double-stranded RNA mimic Poly(I:C). Recombinant CCL20/MIP3alpha was able to inhibit both T-cell-tropic X4/IIIB and macrophage-tropic R5/BaL HIV-1 when virus was directly incubated with CCL20/MIP3alpha but not when CCL20/MIP3alpha was added to cells either prior to infection or post-infection. This suggests that the mechanism of inhibition is likely to be a direct interaction between HIV-1 and CCL20/MIP3alpha.

CONCLUSION

This study demonstrates that CCL20/MIP3alpha is an important endogenous anti-HIV-1 microbicide of the female reproductive tract.

Novel approaches in fighting herpes simplex virus infections

The development of novel strategies to eradicate herpes simplex virus (HSV) is a global public health priority. While acyclovir and related nucleoside analogues provide successful modalities for treatment and suppression, HSV remains highly prevalent worldwide and is a major cofactor fueling the HIV epidemic. HSV is the predominant cause of genital ulcerative disease, and neonatal and sporadic infectious encephalitis. Asymptomatic shedding, which occurs more frequently than previously appreciated, contributes to viral transmission. Acyclovir resistance may be problematic for immunocompromised patients and highlights the need for new safe and effective agents. Ideally, vaccines to prevent infection, drugs to inhibit the establishment of or reactivation from latency, or vaginal microbicides to prevent sexual and perinatal transmission are needed to control the epidemic. This review summarizes current therapeutic options and strategies in development.

Trappin-2/Elafin: a novel innate anti-human immunodeficiency virus-1 molecule of the human female reproductive tract

Trappin-2/Elafin is a serine protease inhibitor that plays a major role as an anti-inflammatory mediator at mucosal surfaces. In addition, Trappin-2/Elafin has antibacterial activity against Gram-positive and Gram-negative bacterial and fungal pathogens. In this study we examined the production of Trappin-2/Elafin by epithelial cells from the human upper and lower female reproductive tract as well as its activity as an anti-human immunodeficiency virus (HIV)-1 molecule. We found that primary uterine, Fallopian tube, cervical and ectocervical epithelial cells produce Trappin-2/Elafin constitutively and that production of Trappin-2/Elafin is enhanced following stimulation with Poly(I:C), especially by the uterine cells. Given the presence of Trappin-2/Elafin in the reproductive tract, we tested the ability of recombinant Trappin-2/Elafin to inhibit HIV-1, an important sexually transmitted pathogen. We found that recombinant Trappin-2/Elafin was able to inhibit both T-cell-tropic X4/IIIB and macrophage-tropic R5/BaL HIV-1 in a dose-dependent manner. The inhibitory activity was observed when virus was incubated with Trappin-2/Elafin but not when Trappin-2/Elafin was added to cells either before infection or after infection. This suggests that the mechanism of inhibition is likely to be a direct interaction between HIV-1 and Trappin-2/Elafin. Additionally, we measured the levels of secreted Trappin-2/Elafin in cervico-vaginal lavages (CVL) from both HIV-positive and HIV-negative women and found that average levels of secreted Trappin-2/Elafin were higher in the CVL from HIV-negative women, although the values did not reach statistical significance. We also found that women at the secretory phase of the menstrual cycle produced more Trappin-2/Elafin in CVL relative to women at the proliferative phase of the menstrual cycle. Our data suggest that Trappin-2/Elafin might be an important endogenous microbicide of the female reproductive tract that is protective against HIV-1.

An African perspective on mucosal immunity and HIV-1

HIV prevention mandates an understanding of the mechanisms of mucosal immunity with attention to some unique features of the epidemic and mucosal environment in the developing world. An effective vaccine will have to induce mucosal protection against a highly diverse virus, which is equipped with a number of immune evasion strategies. Its development will require assessment of mucosal immune responses, and it will have to protect a mucosal environment where inflammation and altered immune responses are common because of the presence of other mucosal infections, such as sexually transmitted infections and parasites, and where nutritional status may also be compromised. Ideally, not only prevention methods would protect adults but also provide cover against gastrointestinal transmission through maternal milk. Prevention might also be complemented by microbicides and circumcision, two alternative approaches to mucosal protection. It seems unlikely that a single solution will work in all instances and intervention might have to act at multiple levels and be tailored to local circumstances. We review here some of the mucosal events associated with HIV infection that are most relevant in an African setting.

Reawakening retrocyclins: ancestral human defensins active against HIV-1

Human alpha and beta defensins contribute substantially to innate immune defenses against microbial and viral infections. Certain nonhuman primates also produce theta-defensins—18 residue cyclic peptides that act as HIV-1 entry inhibitors. Multiple human theta-defensin genes exist, but they harbor a premature termination codon that blocks translation. Consequently, the theta-defensins (retrocyclins) encoded within the human genome are not expressed as peptides. In vivo production of theta-defensins in rhesus macaques involves the post-translational ligation of two nonapeptides, each derived from a 12-residue “demidefensin” precursor. Neither the mechanism of this unique process nor its existence in human cells is known. To ascertain if human cells retained the ability to process demidefensins, we transfected human promyelocytic cells with plasmids containing repaired retrocyclin-like genes. The expected peptides were isolated, their sequences were verified by mass spectrometric analyses, and their anti-HIV-1 activity was confirmed in vitro. Our study reveals for the first time, to our knowledge, that human cells have the ability to make cyclic theta-defensins. Given this evidence that human cells could make theta-defensins, we attempted to restore endogenous expression of retrocyclin peptides. Since human theta-defensin genes are transcribed, we used aminoglycosides to read-through the premature termination codon found in the mRNA transcripts. This treatment induced the production of intact, bioactive retrocyclin-1 peptide by human epithelial cells and cervicovaginal tissues. The ability to reawaken retrocyclin genes from their 7 million years of slumber using aminoglycosides could provide a novel way to secure enhanced resistance to HIV-1 infection.

Defensins are a large family of small antimicrobial peptides that contribute to host defense against a broad spectrum of pathogens. In primates, defensins are divided into three subfamilies—alpha, beta, and theta—on the basis of their disulfide bonding pattern. Theta-defensins were the most recently identified defensin subfamily, isolated initially from white blood cells and bone marrow of rhesus monkeys. They are the only known cyclic peptides in mammals and act primarily by preventing viruses such as HIV-1 from entering cells. Whereas theta-defensin genes are intact in Old World monkeys, in humans they have a premature stop codon that prevents their expression; they thus exist as pseudogenes. In this work, we reveal that, upon correction of the premature termination codon in theta-defensin pseudogenes, human myeloid cells produce cyclic, antiviral peptides (which we have termed “retrocyclins”), indicating that the cells retain the intact machinery to make cyclic peptides. Furthermore, we exploited the ability of aminoglycoside antibiotics to read-through the premature termination codon within retrocyclin transcripts to produce functional peptides that are active against HIV-1. Given that the endogenous production of retrocyclins could also be restored in human cervicovaginal tissues, we propose that aminoglycoside-based topical microbicides might be useful in preventing sexual transmission of HIV-1.

Repairing an ancestral human pseudogene by mutagenesis, or by the application of aminoglycosides to suppress the termination codon, can restore the production of retrocyclins, which are peptides of the defensin family that are remarkable inhibitors of HIV-1 entry into cells.

Defensins in viral infections

Defensins are antimicrobial peptides important to innate host defense. In addition to their direct antimicrobial effect, defensins modulate immune responses. Increasing evidence indicates that defensins exhibit complex functions by positively or negatively modulating infections of both enveloped and non-enveloped viruses. The effects of defensins on viral infections appear to be specific to the defensin, virus and target cell. Regulation of viral infection by defensins is achieved by multiple mechanisms. This review focuses on the interplay between defensins and viral infections, the mechanisms of action of defensins and the in vivo studies of the role of defensins in viral infections.

Cationic polypeptides contribute to the anti-HIV-1 activity of human seminal plasma

Mucosal surfaces of the reproductive tract as well as their secretions have important roles in preventing sexual transmission of HIV-1. In the current study, the majority of the intrinsic anti-HIV-1 activity of human seminal plasma (SP) was determined to reside in the cationic polypeptide fraction. Antiviral assays utilizing luciferase reporter cells and lymphocytic cells revealed the ability of whole SP to prevent HIV-1 infection, even when SP was diluted 3200-fold. Subsequent fractionation by continuous flow acid-urea (AU)-PAGE and antiviral testing revealed that cationic polypeptides within SP were responsible for the majority of anti-HIV-1 activity. A proteomic approach was utilized to resolve and identify 52 individual cationic polypeptides that contribute to the aggregate anti-HIV-1 activity of SP. One peptide fragment of semenogelin I, termed SG-1, was purified from SP by a multistep chromatographic approach, protein sequenced, and determined to exhibit anti-HIV-1 activity against HIV-1. Anti-HIV-1 activity was transient, as whole SP incubated for prolonged time intervals exhibited a proportional decrease in anti-HIV-1 activity that was directly attributed to the degradation of semenogelin I peptides. Collectively, these results indicate that the cationic polypeptide fraction of SP is active against HIV-1, and that semenogelin-derived peptides contribute to the intrinsic anti-HIV-1 activity of SP.

Linkage of T3 and Cpa pilins in the Streptococcus pyogenes M3 pilus

The important human pathogen Streptococcus pyogenes (group A streptococcus, GAS) initiates infection by pilus-mediated attachment to host tissue. Thus, the pilus is an excellent target for design of anti-infective strategies. The T3 pilus of GAS is composed of multiple covalently linked subunits of the T3 protein to which the two minor pilins, Cpa and OrfB, are covalently attached. Because the proteins of GAS pili do not contain either of the motifs required for pilus polymerization in other Gram-positive bacteria, we investigated the residues involved in their linkage. We show that linkage of Cpa to T3 by the sortase family transpeptidase SrtC2 requires the VPPTG motif in the cell wall-sorting signal of Cpa. We also demonstrate that K173 of T3 is required both for T3 polymerization and for attachment of Cpa to T3. Therefore, attachment of Cpa to K173 of a T3 subunit would block further addition of T3 subunits to this end of the growing pilus. This implies that Cpa is located exclusively at the pilus tip, a location supported by immunogold electron microscopy, and suggests that, as for well-studied pili on Gram-negative bacteria, the role of the pilus is to present the adhesin external to the bacterial capsule.

Comprehensive proteomic analysis of human cervical-vaginal fluid using colposcopy samples

Background

Cervical-vaginal fluid (CVF) plays an important role in the prevention of gynecological infections, although little is known about the contribution of CVF proteins to the immunity of the lower female genital tract. In order to analyze the protein composition of human CVF, we used CVF samples that are routinely collected during colposcopy, but are usually discarded. Since these samples are available in large quantities we aimed to analyze their usefulness for proteomics experiments. The samples were analyzed using different prefractionation techniques (ultrafiltration and C₄(RP)-LC protein separation) followed by C₁₈(RP)-LC peptide separation and identification by MALDI-TOF-TOF mass spectrometry. To determine the reproducibility of this proteomics platform we analyzed three technical replicates. Using spectral counting, protein abundances were estimated in a semiquantitative way. We also compared the results obtained in this study with those from previous studies derived from patients with different physiological conditions in order to determine an overlapping protein set.

Results

In total, we were able to identify 339 proteins in human CVF of which 151 proteins were not identified in any other proteomics study on human CVF so far. Those included antimicrobial peptides, such as human beta-defensin 2 and cathelicidin, which were known to be present in CVF, and endometrial proteins such as glycodelin and ribonucleoprotein A. Comparison of our results with previously published data led to the identification of a common protein set of 136 proteins. This overlapping protein set shows increased fractions of immunological and extracellular proteins, confirming the extracellular immunological role of CVF.

Conclusion

We demonstrated here that CVF colposcopy samples can be used in proteomics experiments and hence are applicable for biomarker discovery experiments. The delineation of an overlapping set of proteins that is identified in most proteomics studies on CVF may help in the description of a reference proteome when performing proteomics studies on human CVF.

Levels of innate immune factors in genital fluids: association of alpha defensins and LL-37 with genital infections and increased HIV acquisition

BACKGROUND

Several mucosal innate immune proteins exhibit HIV inhibitory activity and their analogues are potential microbicide candidates. However, their clinical associations and in-vivo role in cervicovaginal host defense against HIV acquisition are poorly defined.

METHODS

Cervicovaginal secretions (CVSs) were collected from HIV uninfected Kenyan sex workers at enrolment into an HIV prevention trial. After trial completion, CVS from participants acquiring HIV (cases) and matched controls were assessed for levels of innate immune factors and HIV neutralizing capacity, by blinded investigators. Cross-sectional and prospective associations of innate immune factors were examined.

RESULTS

CVS contained high levels of defensins (human neutrophil peptide-1-3 and human beta defensin-2-3), LL-37 and secretory leukocyte protease inhibitor. Regulated upon activation normal T-cell expressed and secreted levels were lower, and IFNalpha was undetectable. CVS from 20% of participants neutralized a clade A primary HIV isolate, and 12% neutralized both clade A and C isolates. HIV neutralization was correlated with human neutrophil peptide-1-3 (alpha-defensins) and LL-37 levels. However, alpha-defensin and LL-37 levels were increased in participants with bacterial sexually transmitted infections and were independently associated with increased HIV acquisition in multivariate analysis.

CONCLUSIONS

Despite significant HIV inhibitory activity, cervicovaginal levels of alpha-defensins and LL-37 were associated with increased HIV acquisition, perhaps due to their association with bacterial sexually transmitted infections.