Andrea Introini

CD49a Expression Defines Tissue-Resident CD8+ T Cells Poised for Cytotoxic Function in Human Skin

SUMMARY Tissue‐resident memory T (Trm) cells form a heterogeneous population that provides localized protection against pathogens. Here, we identify CD49a as a marker that differentiates CD8+ Trm cells on a compartmental and functional basis. In human skin epithelia, CD8+CD49a+ Trm cells produced interferon‐&ggr;, whereas CD8+CD49a− Trm cells produced interleukin‐17 (IL‐17). In addition, CD8+CD49a+ Trm cells from healthy skin rapidly induced the expression of the effector molecules perforin and granzyme B when stimulated with IL‐15, thereby promoting a strong cytotoxic response. In skin from patients with vitiligo, where melanocytes are eradicated locally, CD8+CD49a+ Trm cells that constitutively expressed perforin and granzyme B accumulated both in the epidermis and dermis. Conversely, CD8+CD49a– Trm cells from psoriasis lesions predominantly generated IL‐17 responses that promote local inflammation in this skin disease. Overall, CD49a expression delineates CD8+ Trm cell specialization in human epithelial barriers and correlates with the effector cell balance found in distinct inflammatory skin diseases. Graphical Abstract Figure. No Caption available. HighlightsCD49a expression marks CD8+ Trm cells poised for IFN‐&ggr; production in human skinIL‐15 drives potent cytotoxic capacity in CD49a+ Trm cellsIL‐17 is preferentially produced by CD49a− CD8+ Trm cells in the skinCD49a+ versus CD49‐ Trm cell functional dichotomy is preserved in vitiligo and psoriasis &NA; Tissue‐resident memory T (Trm) cells provide localized adaptive immunity in peripheral tissues. Cheuk et al. identify cytotoxic CD49a+CD8+ Trm cells and IL‐17‐producing CD49a−CD8+ Trm cells in healthy human skin. The functional dichotomy of pathogenic Trm cells based on CD49a expression is preserved in focal skin diseases vitiligo and psoriasis.

MAIT cells reside in the female genital mucosa and are biased towards IL-17 and IL-22 production in response to bacterial stimulation

The female genital tract (FGT) mucosa is a critically important site for immune defense against microbes. Mucosal-associated invariant T (MAIT) cells are an innate-like T-cell population that recognizes microbial riboflavin metabolite antigens in an MR1-dependent manner. The role of MAIT cells in the FGT mucosa is unknown. Here, we found that MAIT cells and MR1+ antigen-presenting cells were present in the upper and lower FGT, with distinct tissue localization of MAIT cells in endometrium vs. cervix. The MAIT cells from the FGT and blood displayed a distinct phenotype with expression of interleukin (IL)-18Rα, CD127, α4β7, PD-1, as well as the transcription factors promyelocytic leukemia zinc finger (PLZF), RORγt, Helios, Eomes, and T-bet. Their expression levels of PLZF and Eomes were lower in the FGT compared with blood. When stimulated with Escherichia coli, MAIT cells from the FGT displayed a bias towards IL-17 and IL-22 expression, whereas blood MAIT cells produced primarily IFN-γ, TNF, and Granzyme B. Furthermore, both FGT- and blood-derived MAIT cells were polyfunctional and contributed to the T-cell-mediated response to E. coli. Thus, MAIT cells in the genital mucosa have a distinct IL-17/IL-22 profile and may have an important role in the immunological homeostasis and control of microbes at this site.

Depot medroxyprogesterone acetate use is associated with elevated innate immune effector molecules in cervicovaginal secretions of HIV-1-uninfected women

Objective:The effects of sex hormones on the immune defenses of the female genital mucosa and its susceptibility to infections are poorly understood. The injectable hormonal contraceptive depot medroxyprogesterone acetate (DMPA) may increase the risk for HIV-1 acquisition. We assessed the local concentration in the female genital mucosa of cationic polypeptides with reported antiviral activity in relation to DMPA use. Methods:HIV-1–uninfected women were recruited from among couples testing for HIV in Nairobi, Kenya. Cervicovaginal secretion samples were collected, and the concentrations of HNP1–3, LL-37, lactoferrin, HBD-2, and SLPI were measured by enzyme-linked immunosorbent assays. Levels of cationic polypeptides in cervicovaginal secretions were compared between women who were not using hormonal contraception and those using DMPA, oral, or implantable contraception. Results:Among 228 women, 165 (72%) reported not using hormonal contraception at enrollment, 41 (18%) used DMPA, 16 (7%) used an oral contraceptive, and 6 (3%) used a contraceptive implant. Compared with nonusers of hormonal contraception, DMPA users had significantly higher mean levels of HNP1–3 (2.38 vs. 2.04 log10 ng/mL; P = 0.024), LL-37 (0.81 vs. 0.40 log10 ng/mL; P = 0.027), and lactoferrin (3.03 vs. 2.60 log10 ng/mL; P = 0.002), whereas SLPI and HBD-2 were similar. Conclusions:Although all analyzed cationic polypeptides have intrinsic antiviral capacity, their interaction and cumulative effect on female genital mucosa susceptibility to infections in vivo has yet to be unraveled. This study suggests a potential mechanism underlying the effect of DMPA on the innate immune defenses, providing a rationale to investigate its effect on HIV-1 acquisition risk.

Blood pressure regulation by CD4+ lymphocytes expressing choline acetyltransferase

Blood pressure regulation is known to be maintained by a neuro-endocrine circuit, but whether immune cells contribute to blood pressure homeostasis has not been determined. We previously showed that CD4+ T lymphocytes that express choline acetyltransferase (ChAT), which catalyzes the synthesis of the vasorelaxant acetylcholine, relay neural signals. Here we show that these CD4+CD44hiCD62Llo T helper cells by gene expression are a distinct T-cell population defined by ChAT (CD4 TChAT). Mice lacking ChAT expression in CD4+ cells have elevated arterial blood pressure, compared to littermate controls. Jurkat T cells overexpressing ChAT (JTChAT) decreased blood pressure when infused into mice. Co-incubation of JTChAT and endothelial cells increased endothelial cell levels of phosphorylated endothelial nitric oxide synthase, and of nitrates and nitrites in conditioned media, indicating increased release of the potent vasorelaxant nitric oxide. The isolation and characterization of CD4 TChAT cells will enable analysis of the role of these cells in hypotension and hypertension, and may suggest novel therapeutic strategies by targeting cell-mediated vasorelaxation.

Seminal plasma induces inflammation and enhances HIV-1 replication in human cervical tissue explants

The most immediate and evident effect of mucosal exposure to semen in vivo is a local release of proinflammatory mediators accompanied by an influx of leukocytes into the female genital mucosa (FGM). The implication of such response in HIV-1 transmission has never been addressed due to limitations of currently available experimental models. Using human tissue explants from the uterine cervix, we developed a system of mucosal exposure to seminal plasma (SP) that supports HIV-1 replication. Treatment of ectocervical explants with SP resulted in the upregulation of inflammatory and growth factors, including IL-6, TNF, CCL5, CCL20, CXCL1, and CXCL8, and IL1A, CSF2, IL7, PTGS2, as evaluated by measuring protein levels in explant conditioned medium (ECM) and gene expression in tissue. SP treatment was also associated with increased recruitment of monocytes and neutrophils, as observed upon incubation of peripheral blood leukocytes with ECM in a transwell system. To evaluate the impact of the SP-mediated response on local susceptibility to HIV-1, we infected ectocervical explants with the CCR5-tropic variant HIV-1BaL either in the presence of SP, or after explant pre-incubation with SP. In both experimental settings SP enhanced virus replication as evaluated by HIV-1 p24gag released in explant culture medium over time, as well as by HIV-1 DNA quantification in explants infected in the presence of SP. These results suggest that a sustained inflammatory response elicited by SP soon after coitus may promote HIV-1 transmission to the FGM. Nevertheless, ectocervical tissue explants did not support the replication of transmitted/founder HIV-1 molecular clones, regardless of SP treatment. Our system offers experimental and analytical advantages over traditional models of HIV-1 transmission for the study of SP immunoregulatory effect on the FGM, and may provide a useful platform to ultimately identify new determinants of HIV-1 infection at this site.

Innate Invariant NKT Cell Recognition of HIV-1–Infected Dendritic Cells Is an Early Detection Mechanism Targeted by Viral Immune Evasion

Invariant NKT (iNKT) cells are innate-like T cells that respond rapidly with a broad range of effector functions upon recognition of glycolipid Ags presented by CD1d. HIV-1 carries Nef- and Vpu-dependent mechanisms to interfere with CD1d surface expression, indirectly suggesting a role for iNKT cells in control of HIV-1 infection. In this study, we investigated whether iNKT cells can participate in the innate cell–mediated immune response to HIV-1. Infection of dendritic cells (DCs) with Nef- and Vpu-deficient HIV-1 induced upregulation of CD1d in a TLR7-dependent manner. Infection of DCs caused modulation of enzymes in the sphingolipid pathway and enhanced expression of the endogenous glucosylceramide Ag. Importantly, iNKT cells responded specifically to rare DCs productively infected with Nef- and Vpu-defective HIV-1. Transmitted founder viral isolates differed in their CD1d downregulation capacity, suggesting that diverse strains may be differentially successful in inhibiting this pathway. Furthermore, both iNKT cells and DCs expressing CD1d and HIV receptors resided in the female genital mucosa, a site where HIV-1 transmission occurs. Taken together, these findings suggest that innate iNKT cell sensing of HIV-1 infection in DCs is an early immune detection mechanism, which is independent of priming and adaptive recognition of viral Ag, and is actively targeted by Nef- and Vpu-dependent viral immune evasion mechanisms.

Progesterone-Based Intrauterine Device Use Is Associated with a Thinner Apical Layer of the Human Ectocervical Epithelium and a Lower ZO-1 mRNA Expression

ABSTRACT Currently, whether hormonal contraceptives affect male to female human immunodeficiency virus (HIV) transmission is being debated. In this study, we investigated whether the use of progesterone-based intrauterine devices (pIUDs) is associated with a thinning effect on the ectocervical squamous epithelium, down-regulation of epithelial junction proteins, and/or alteration of HIV target cell distribution in the human ectocervix. Ectocervical tissue biopsies from healthy premenopausal volunteers using pIUDs were collected and compared to biopsies obtained from two control groups, namely women using combined oral contraceptives (COCs) or who do not use hormonal contraceptives. In situ staining and image analysis were used to measure epithelial thickness and the presence of HIV receptors in tissue biopsies. Messenger RNA levels of epithelial junction markers were measured by quantitative PCR. The epithelial thickness displayed by women in the pIUD group was similar to those in the COC group, but significantly thinner as compared to women in the no hormonal contraceptive group. The thinner epithelial layer of the pIUD group was specific to the apical layer of the ectocervix. Furthermore, the pIUD group expressed significantly lower levels of the tight junction marker ZO-1 within the epithelium as compared to the COC group. Similar expression levels of HIV receptors and coreceptors CD4, CCR5, DC-SIGN, and Langerin were observed in the three study groups. Thus, women using pIUD displayed a thinner apical layer of the ectocervical epithelium and reduced ZO-1 expression as compared to control groups. These data suggest that pIUD use may weaken the ectocervical epithelial barrier against invading pathogens, including HIV.

Expression Profiles of Antimicrobial Peptides in the Genital Tract of Women Using Progesterone Intrauterine Devices Versus Combined Oral Contraceptives

Sex hormones can influence the immune defenses of the female genital tract (FGT) and its susceptibility to infections. Here we investigated the effect of different hormonal contraceptives on the production of antimicrobial peptides (AMPs) in different compartments of the female genital mucosa (FGM), secretions and tissue.

Human Immunodeficiency Virus-Infected Women Have High Numbers of CD103−CD8+ T Cells Residing Close to the Basal Membrane of the Ectocervical Epithelium

Background Genital mucosa is the main portal of entry for various incoming pathogens, including human immunodeficiency virus (HIV), hence it is an important site for host immune defenses. Tissue-resident memory T (TRM) cells defend tissue barriers against infections and are characterized by expression of CD103 and CD69. In this study, we describe the composition of CD8+ TRM cells in the ectocervix of healthy and HIV-infected women. Methods Study samples were collected from healthy Swedish and Kenyan HIV-infected and uninfected women. Customized computerized image-based in situ analysis was developed to assess the ectocervical biopsies. Genital mucosa and blood samples were assessed by flow cytometry. Results Although the ectocervical epithelium of healthy women was populated with bona fide CD8+ TRM cells (CD103+CD69+), women infected with HIV displayed a high frequency of CD103-CD8+ cells residing close to their epithelial basal membrane. Accumulation of CD103-CD8+ cells was associated with chemokine expression in the ectocervix and HIV viral load. CD103+CD8+ and CD103-CD8+ T cells expressed cytotoxic effector molecules in the ectocervical epithelium of healthy and HIV-infected women. In addition, women infected with HIV had decreased frequencies of circulating CD103+CD8+ T cells. Conclusions Our data provide insight into the distribution of CD8+ TRM cells in human genital mucosa, a critically important location for immune defense against pathogens, including HIV.

The vaginal microbiome amplifies sex hormone-associated cyclic changes in cervicovaginal inflammation and epithelial barrier disruption

Susceptibility to HIV is associated with the menstrual cycle and vaginal microbiome, but their collective impact on vaginal inflammation remains unclear. Here, we characterized the cervicovaginal proteome, inflammation, and microbiome community structure and function during the menstrual cycle.