Interferon ε restricts Zika virus infection in the female reproductive tract.

Interferon ε (IFNε) is a unique type I IFN that has been implicated in host defense against sexually transmitted infections (STIs). Zika virus (ZIKV), an emerging pathogen, can infect the female reproductive tract (FRT) and cause devastating diseases, particularly in pregnant women. How IFNε contributes to protection against ZIKV infection in vivo is unknown. Here, we show that IFNε plays a critical role in host protection against vaginal ZIKV infection in mice. We found that IFNε was expressed not only by epithelial cells in the FRT, but also by certain immune and other cells at baseline or after exposure to viruses or specific TLR agonists. IFNε-deficient mice exhibited abnormalities in the epithelial border and underlying tissue in the cervicovaginal tract, and these defects were associated with increased susceptibility to vaginal, but not subcutaneous ZIKV infection. IFNε-deficiency resulted in an increase in magnitude, duration, and depth of ZIKV infection in the FRT. Critically, intravaginal administration of recombinant IFNε protected Ifnε-/- mice and highly susceptible Ifnar1-/- mice against vaginal ZIKV infection, indicating that IFNε was sufficient to provide protection even in the absence of signals from other type I IFNs and in an IFNAR1-independent manner. Our findings reveal a potentially critical role for IFNε in mediating protection against transmission of ZIKV in the context of sexual contact.

Interferon ɛ restricts Zika virus infection in the female reproductive tract.

Interferon ɛ (IFNɛ) is a unique type I IFN that has been implicated in host defense against sexually transmitted infections. Zika virus (ZIKV), an emerging pathogen, can infect the female reproductive tract (FRT) and cause devastating diseases, particularly in pregnant women. How IFNɛ contributes to protection against ZIKV infection in vivo is unknown. In this study, we show that IFNɛ plays a critical role in host protection against vaginal ZIKV infection in mice. We found that IFNɛ was expressed not only by epithelial cells in the FRT but also by immune and stromal cells at baseline or after exposure to viruses or specific Toll-like receptor (TLR) agonists. IFNɛ-deficient mice exhibited abnormalities in the epithelial border and underlying tissue in the cervicovaginal tract, and these defects were associated with increased susceptibility to vaginal but not subcutaneous ZIKV infection. IFNɛ deficiency resulted in an increase in magnitude, duration, and depth of ZIKV infection in the FRT. Critically, intravaginal administration of recombinant IFNɛ protected Ifnɛ-/- mice and highly susceptible Ifnar1-/- mice against vaginal ZIKV infection, indicating that IFNɛ was sufficient to provide protection even in the absence of signals from other type I IFNs and in an IFNAR1-independent manner. Our findings reveal a potentially critical role for IFNɛ in mediating protection against the transmission of ZIKV in the context of sexual contact.

A therapeutic strategy to target distinct sources of IgE and durably reverse allergy.

Immunoglobulin E (IgE) is a key driver of type 1 hypersensitivity reactions and allergic disorders, which are globally increasing in number and severity. Although eliminating pathogenic IgE may be a powerful way to treat allergy, no therapeutic strategy reported to date can fully ablate IgE production. Interleukin-4 receptor α (IL-4Rα) signaling is required for IgE class switching, and IL-4Rα blockade gradually reduces, but does not eliminate, IgE. The persistence of IgE after IL-4Rα blockade may be due to long-lived IgE+ plasma cells that maintain serological memory to allergens and thus may be susceptible to plasma cell-targeted therapeutics. We demonstrate that transient administration of a B cell maturation antigen x CD3 (BCMAxCD3) bispecific antibody markedly depletes IgE, as well as other immunoglobulins, by ablating long-lived plasma cells, although IgE and other immunoglobulins rapidly rebound after treatment. Concomitant IL-4Rα blockade specifically and durably prevents the reemergence of IgE by blocking IgE class switching while allowing the restoration of other immunoglobulins. Moreover, this combination treatment prevented anaphylaxis in mice. Together with additional cynomolgus monkey and human data, our studies demonstrate that allergic memory is primarily maintained by both non-IgE+ memory B cells that require class switching and long-lived IgE+ plasma cells. Our combination approach to durably eliminate pathogenic IgE has potential to benefit allergy in humans while preserving antibody-mediated immunity.

Competition-Based Cell Assay Employing Soluble T Cell Receptors to Assess MHC Class II Antigen Processing and Presentation.

Accurate assessment of antigen-specific immune responses is critical in the development of safe and efficacious biotherapeutics and vaccines. Endosomal processing of a protein antigen followed by presentation on major histocompatibility complex (MHC) class II constitute necessary steps in the induction of CD4+ T cell immune responses. Current preclinical methods for assessing immunogenicity risk consist of in vitro cell-based assays and computational prediction tools. Cell-based assays are time and labor-intensive while in silico methodologies have limitations. Here, we propose a novel cell-based assay capable of investigating an antigen's endosomal processing and MHC class II presentation capabilities. This novel assay relies on competition between epitopes for MHC class II binding and employs labeled soluble T cell receptors (sTCRs) as detectors of epitope presentation.

Depot medroxyprogesterone acetate administration increases cervical CCR5+CD4+ T cells and induces immunosuppressive milieu at the cervicovaginal mucosa.

OBJECTIVES: Depot medroxyprogesterone acetate (Depo-Provera) is the most commonly used injectable hormone contraceptive in Sub-Saharan Africa where HIV incidence is high. We determined the impact of Depo-Provera on cervical immune cells and mediators in healthy women. METHODS: In this longitudinal study, vaginal, endocervical, and rectal swabs were collected at baseline (visit 1), 1 month (visit 2), and 3 months (visit 3) after Depo-Provera injection. Cervical cells were collected by cytobrush and immune markers on cervical CD4 T cells were analyzed by multicolor flow cytometry at three different visits. The levels of immune mediators in cytobrush supernatants as well as vaginal, cervical, and rectal secretions from swabs were analyzed by multiplex assays and ELISA. RESULTS: Compared with baseline levels, we found a significant increase in the frequency of cervical CCR5CD4 T cells and a significant decrease in the frequency of cervical central memory CD4 T cells. Depo-Provera treatment had little effect on expression of immune mediators in rectal mucosa but significantly suppressed numerous immune mediators at cervicovaginal mucosa. Levels of MCP-1, G-CSF, IL-6, IL-10, GM-CSF, and IP-10 were significantly decreased in both vaginal and cervical secretions after Depo-Provera injection. In cervical samples collected by cytobrush, we found reduced levels of 22 of 25 immune mediators after Depo-Provera injection. Changes in immune mediators differed between vaginal and cervical mucosa, demonstrating compartment-specific responses. CONCLUSION: Depo-Provera altered immune profiles of cervical CD4 T cells and suppressed host immune response at cervicovaginal mucosa, suggesting its likely effect on transmission of sexually transmitted infections including HIV.

Differential effects of depot medroxyprogesterone acetate administration on vaginal microbiome in Hispanic White and Black women.

The use of depot medroxyprogesterone acetate (DMPA), a 3-monthly injectable hormonal contraceptive, is associated with an increased risk of HIV acquisition possibly through alteration of the vaginal microbiome. In this longitudinal interventional study, we investigated the impact of DMPA administration on the vaginal microbiome in Hispanic White and Black women at the baseline (visit 1), 1 month (visit 2), and 3 months (visit 3) following DMPA treatment by using 16S rRNA gene sequencing. No significant changes in the vaginal microbiome were observed after DMPA treatment when Hispanic White and Black women were analysed as a combined group. However, DMPA treatment enriched total vaginosis-associated bacteria (VNAB) and Prevotella at visit 2, and simplified the correlational network in the vaginal microbiome in Black women, while increasing the network size in Hispanic White women. The microbiome in Black women became more diversified and contained more VNAB than Hispanic White women after DMPA treatment. While the Firmicutes to Bacteroidetes (F/B) ratio and Lactobacillus to Prevotella (L/P) ratio were comparable between Black and Hispanic White women at visit 1, both ratios were lower in Black women than in Hispanic White women at visit 2. In conclusion, DMPA treatment altered the community network and enriched VNAB in Black women but not in Hispanic White women. The Lactobacillus deficiency and enrichment of VNAB may contribute to the increased risk of HIV acquisition in Black women. Future studies on the impact of racial differences on the risk of HIV acquisition will offer insights into developing effective strategies for HIV prevention. Abbreviations: DMPA: depot medroxyprogesterone acetate; PCR: polymerase chain reaction; OTU: operational taxonomic unit; STI: sexually transmitted infections; VNAB: vaginosis-associated bacteria.

Depot medroxyprogesterone acetate administration alters immune markers for HIV preference and increases susceptibility of peripheral CD4+ T cells to HIV infection.

Depot medroxyprogesterone acetate (Depo-Provera) has been associated with an increased risk of HIV acquisition. In a longitudinal study, we investigated the impact of Depo-Provera use by healthy women on expression of immune markers for HIV preference and on HIV infection ex vivo at baseline (visit 1), one month (visit 2) and three months (visit 3) after Depo-Provera treatment. We found a significant increase in the frequency and expression of integrin α4ß7 on CD4+ T cells at visit 2. Interestingly, Hispanic but not black women exhibited a significant increase in integrin α4ß7 cell numbers and expression levels at visit 2, whereas, black but not Hispanic women exhibited a significant change in CCR5 and CD38 expression levels between visit 2 and visit 3. The frequency of terminal effector memory CD4+ T cells decreased significantly in black women from visit 1 to visit 3. Virus production following ex vivo HIV infection of PBMCs was increased at visit 3 compared to visit 1. In black women, the frequency of HIV p24+CD4+ T cells was higher at visit 3 than at visit 1. Expression of integrin α4ß7 on HIV p24+CD4+ T cells following ex vivo infection at visit 2 was significantly less than at visit 1. These results demonstrate that Depo-Provera alters the immune profile of peripheral CD4+ T cells and increases susceptibility to HIV infection ex vivo. The observation that these effects differed between women of different ethnicities has implications for developing effective and targeted strategies for HIV prevention.

Differential regulation of IFNα, IFNß and IFNε gene expression in human cervical epithelial cells.

Interferonε (IFNε) is a unique type I IFN that has distinct functions from IFNα/ß. IFNε is constitutively expressed at mucosal tissues, including the female genital mucosa, and is reported to be modulated by estrogen and seminal plasma. However, its regulation by cytokines, including TNFα, IL-1ß, IL-6, IL-8, IL-17, IL-22 and IFNα, which are commonly present in the female genital mucosa, is not well documented in freshly isolated primary cervical cells from tissues. We determined the effect of these cytokines on gene expression of type I IFNs in an immortalized endocervical epithelial cell line (A2EN) and in primary cervical epithelial cells. Several pro-inflammatory cytokines were found to induce IFNε, and TNFα induced the strongest response in both cell types. Pretreatment of cells with the IκB inhibitor, which blocks the NF-κB pathway, suppressed TNFα-mediated IFNε gene induction and promoter activation. Expression of IFNα, IFNß, and IFNε was differentially regulated in response to various cytokines. Taken together, our results show that regulation of these IFNs depends on cell type, cytokine concentration, and incubation time, highlighting the complexity of the cytokine network in the cervical epithelium.

IFN-ε protects primary macrophages against HIV infection.

IFN-ε is a unique type I IFN that is not induced by pattern recognition response elements. IFN-ε is constitutively expressed in mucosal tissues, including the female genital mucosa. Although the direct antiviral activity of IFN-ε was thought to be weak compared with IFN-α, IFN-ε controls Chlamydia muridarum and herpes simplex virus 2 in mice, possibly through modulation of immune response. We show here that IFN-ε induces an antiviral state in human macrophages that blocks HIV-1 replication. IFN-ε had little or no protective effect in activated CD4+ T cells or transformed cell lines unless activated CD4+ T cells were infected with replication-competent HIV-1 at a low MOI. The block to HIV infection of macrophages was maximal after 24 hours of treatment and was reversible. IFN-ε acted on early stages of the HIV life cycle, including viral entry, reverse transcription, and nuclear import. The protection did not appear to operate through known type I IFN-induced HIV host restriction factors, such as APOBEC3A and SAMHD1. IFN-ε-stimulated immune mediators and pathways had the signature of type I IFNs but were distinct from IFN-α in macrophages. IFN-ε induced significant phagocytosis and ROS, which contributed to the block to HIV replication. These findings indicate that IFN-ε induces an antiviral state in macrophages that is mediated by different factors than those induced by IFN-α. Understanding the mechanism of IFN-ε-mediated HIV inhibition through immune modulation has implications for prevention.

Integrin α4ß7 Expression Increases HIV Susceptibility in Activated Cervical CD4+ T Cells by an HIV Attachment-Independent Mechanism.

BACKGROUND: CD4 T cells are crucial for the establishment and dissemination of HIV in mucosal tissues during acute infection. Studies indicate that integrin α4ß7 CD4 T cells are preferentially infected by HIV in vitro and during acute SIV infection. The integrin α4ß7 is thought to promote HIV capture by target cells; however, the role of integrin α4ß7 in HIV transmission remains controversial. In this study, we characterized immune phenotypes of human cervical T cells and examined HIV preference in integrin α4ß7 CD4 T cells. In vitro all-trans retinoic acid-differentiated peripheral CD4 T cells (atRA-differentiated cells) were included as a comparison. RESULTS: In both peripheral and cervical cells, the majority of HIV p24 cells were activated CD4 T cells expressing integrin α4ß7. Among infected atRA-differentiated cells, the frequency of CCR5 expression was higher in HIV p24 cells than in HIV p24 cells; no such difference was observed in cervical cells. Neither the cyclic hexapeptide CWLDVC nor a monoclonal antibody against integrin α4ß7 blocked HIV attachment or gp120 binding to target cells regardless of the presence of CD4, indicating that integrin α4ß7 did not facilitate HIV capture by target cells. CONCLUSIONS: Integrin α4ß7 expression increases HIV susceptibility, but the mechanism is not through promoting HIV binding to target cells.

17ß-estradiol protects primary macrophages against HIV infection through induction of interferon-alpha.

Estrogen has been shown to increase resistance to HIV/SIV transmission by increasing the thickness of the genital epithelium. The immunological role of estrogen in HIV infection of primary target cells is less well characterized. We have found that primary macrophages are a target for anti-HIV activity of 17ß-estradiol (E2). E2 did not affect surface expression of CD4 and HIV co-receptors nor HIV attachment to monocyte-derived macrophages (MDMs). In addition, E2 treatment blocked infection by a co-receptor-independent HIV-1VSV-G pseudotyped virus. Quantitative polymerase chain reaction analysis of HIV reverse transcribed DNA products indicated that E2 blocked HIV reverse transcription. E2 upregulated gene expression of interferons (IFNs) in MDMs from multiple donors. However, induction of host restriction factors APOBEC3G, APOBEC3F, or SAMHD1 was not consistent, with exception of APOBEC3A. Anti-HIV activity of E2 was abolished in the presence of IFN-α neutralizing antibody, and was absent in bone marrow-derived macrophages from IFN-α receptor deficient mice. Interestingly, HIV overcame E2-mediated HIV inhibition by suppressing induction of IFNs when MDMs were exposed to HIV before E2 treatment. These results offer a new mechanism of E2 on HIV inhibition. Future studies on the interplay between HIV and E2-mediated innate immune responses will likely provide insights relevant for development of effective strategies for HIV prevention.

Anti-HIV activity of human defensin 5 in primary CD4+ T cells under serum-deprived conditions is a consequence of defensin-mediated cytotoxicity.

BACKGROUND: We have previously shown that human defensin 5 (HD5) promotes HIV infectivity in both primary CD4+ T cells and HeLa cells expressing CD4 and CCR5. HD5 is induced in response to sexually transmitted infections (STIs) such as Chlamydia trachomatis and Neisseria gonorrhoeae, suggesting it plays a role in STI-mediated enhancement of HIV transmission. In contrast to our findings, a recent study reports that HD5 has an anti-HIV effect in primary CD4+ T cells under serum-deprived conditions. To resolve these apparently contradictory observations, we investigated experimental parameters that might contribute to contrasting effects of HD5. RESULTS: Serum-deprived culture conditions were associated with anti-HIV activity. In contrast to the dependence of the HIV enhancing effect on HD5 structure, the anti-HIV activity in serum-deprived primary CD4+ T cells was independent of HD5 structure as the linear peptide [Abu] HD5 exhibited similar anti-HIV activity. Under serum deprived conditions, HD5 blocked CD4-receptor-independent HIV-1vsv infection before or after viral entry. We found that HD5 and its linear form induced significant cell death in primary CD4+ T cells under serum-deprived culture conditions. HD5-mediated apoptosis was observed as early as 2 h after addition of defensins to serum-deprived primary CD4+ T cells. In contrast to primary CD4+ T cells, HD5 did not induce cytotoxicity and promote HIV infectivity of HeLa-CD4-CCR5 cells under serum-deprived conditions. CONCLUSIONS: These results indicate that under serum-deprived culture conditions HD5 is toxic for primary CD4+ T cells, warranting caution in data interpretation.