Transient Increases in Inflammation and Proapoptotic Potential Are Associated with the HESN Phenotype Observed in a Subgroup of Kenyan Female Sex Workers.

Interferon (IFN) -stimulated genes (ISGs) are critical effectors of IFN response to viral infection, but whether ISG expression is a correlate of protection against HIV infection remains elusive. A well-characterized subcohort of Kenyan female sex workers, who, despite being repeatedly exposed to HIV-1 remain seronegative (HESN), exhibit reduced baseline systemic and mucosal immune activation. This study tested the hypothesis that regulation of ISGs in the cells of HESN potentiates a robust antiviral response against HIV. Transcriptional profile of a panel of ISGs with antiviral function in PBMC and isolated CD4+ T cells from HESN and non-HESN sex worker controls were defined following exogenous IFN-stimulation using relative RT-qPCR. This study identified a unique profile of proinflammatory and proapoptotic ISGs with robust but transient responses to exogenous IFN-γ and IFN-α2 in HESN cells. In contrast, the non-HESN cells had a strong and prolonged proinflammatory ISG profile at baseline and following IFN challenge. Potential mechanisms may include augmented bystander apoptosis due to increased TRAIL expression (16-fold), in non-HESN cells. The study also identified two negative regulators of ISG induction associated with the HESN phenotype. Robust upregulation of SOCS-1 and IRF-1, in addition to HDM2, could contribute to the strict regulation of proinflammatory and proapoptotic ISGs in HESN cells. As reducing IRF-1 in the non-HESN cells resulted in the identified HESN ISG profile, and decreased HIV susceptibility, the unique HESN ISG profile could be a correlate of protection against HIV infection.

Endothelial Cells Promote Productive HIV Infection of Resting CD4+ T Cells by an Integrin-Mediated Cell Adhesion-Dependent Mechanism.

Resting CD4+ T cells are primary targets of early HIV infection events in vivo, but do not readily support HIV replication in vitro. This barrier to infection can be overcome by exposing resting CD4+ T cells to endothelial cells (ECs). ECs line blood vessels and direct T cell trafficking into inflamed tissues. Cell trafficking pathways have been shown to have overlapping roles in facilitating HIV replication, but their relevance to EC-mediated enhancement of HIV susceptibility in resting CD4+ T cells has not previously been examined. We characterized the phenotype of primary human resting CD4+ T cells that became productively infected with HIV when cocultured with primary human blood and lymphatic ECs. The infected CD4+ T cells were primarily central memory cells enriched for high expression of the integrins LFA-1 and VLA-4. ICAM-1 and VCAM-1, the cognate ligands for LFA-1 and VLA-4, respectively, were expressed by the ECs in the coculture. Blocking LFA-1 and VLA-4 on resting CD4+ T cells inhibited infection by 65.4%-96.9%, indicating that engagement of these integrins facilitates EC-mediated enhancement of productive HIV infection in resting CD4+ T cells. The demonstration that ECs influence cellular HIV susceptibility of resting memory CD4+ T cells through cell trafficking pathways engaged during the transmigration of T cells into tissues highlights the physiological relevance of these findings for HIV acquisition and opportunities for intervention.

Serological and cellular inflammatory signatures in end-stage kidney disease and latent tuberculosis.

OBJECTIVES: Tuberculosis comorbidity with chronic diseases including diabetes, HIV and chronic kidney disease is of rising concern. In particular, latent tuberculosis infection (LTBI) comorbidity with end-stage kidney disease (ESKD) is associated with up to 52.5-fold increased risk of TB reactivation to active tuberculosis infection (ATBI). The immunological mechanisms driving this significant rise in TB reactivation are poorly understood. To contribute to this understanding, we performed a comprehensive assessment of soluble and cellular immune features amongst a unique cohort of patients comorbid with ESKD and LTBI. METHODS: We assessed the plasma and cellular immune profiles from patients with and without ESKD and/or LTBI (N = 40). We characterised antibody glycosylation, serum complement and cytokine levels. We also assessed classical and non-classical monocytes and T cells with flow cytometry. Using a systems-based approach, we identified key immunological features that discriminate between the different disease states. RESULTS: Individuals with ESKD exhibited a highly inflammatory plasma profile and an activated cellular state compared with those without ESKD, including higher levels of inflammatory antibody Fc glycosylation structures and activated CX3CR1+ monocytes that correlate with increased inflammatory plasma cytokines. Similar elevated inflammatory signatures were also observed in ESKD+/LTBI+ compared with ESKD-/LTBI+, suggesting that ESKD induces an overwhelming inflammatory immune state. In contrast, no significant inflammatory differences were observed when comparing LTBI+ and LTBI- individuals. CONCLUSION: Our study highlights the highly inflammatory state induced by ESKD. We hypothesise that this inflammatory state could contribute to the increased risk of TB reactivation in ESKD patients.

Plasma Oxylipins Levels in Nonalcoholic Fatty Liver Disease.

BACKGROUND: Activation of innate immunity by gut-derived immunogens such as lipopolysaccharides (LPS) may play an important role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Whether NAFLD-associated lipid disturbances and polyunsaturated fatty acid (PUFA) metabolism in particular contribute to heightened innate immunity, remains to be determined. OBJECTIVE: To determine if oxylipins, metabolic products of PUFA metabolism, enhance innate immune reactivity alone and/or following exposure to LPS. METHODS: Plasma and peripheral blood mononuclear cells (PBMC) were collected from 35 NAFLD patients and 8 healthy controls. Oxylipin levels were documented by HPLC-MS/MS, cytokines (IL-1, IL-6, IL-10, and TNF-α) by ELISA, and chemokine receptors (CCR1 and CCR2) by flow cytometry. RESULTS: Mean plasma levels of four pro-inflammatory oxylipins (Tetranor 12-HETE, 20-HETE, 8-HETrE, and 7-HDoHE) were significantly elevated in NAFLD patients compared to healthy controls. However, the levels did not correlate with the severity of liver injury as reflected by serum aminotransferases, ck18M30, and Fib-4 determinations. In vitro, 20-HETE (0.01-100 nM), the plasma oxylipin with the most significantly elevated plasma levels, did not alter NAFLD or control PBMC cytokine release or enhance the increases in cytokine release following 24 h of LPS exposure. Similarly, 20-HETE alone did not alter PBMC CCR1 or CCR2 expression or LPS-induced downregulation of these receptors. CONCLUSIONS: Pro-inflammatory oxylipin levels are increased in NAFLD, but these metabolites do not appear to drive short-term direct or LPS-induced increases in PBMC cytokine release or chemotaxis.

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.

Myristoylation: An Important Protein Modification in the Immune Response.

Protein N-myristoylation is a cotranslational lipidic modification specific to the alpha-amino group of an N-terminal glycine residue of many eukaryotic and viral proteins. The ubiquitous eukaryotic enzyme, N-myristoyltransferase, catalyzes the myristoylation process. Precisely, attachment of a myristoyl group increases specific protein-protein interactions leading to subcellular localization of myristoylated proteins with its signaling partners. The birth of the field of myristoylation, a little over three decades ago, has led to the understanding of the significance of protein myristoylation in regulating cellular signaling pathways in several biological processes especially in carcinogenesis and more recently immune function. This review discusses myristoylation as a prerequisite step in initiating many immune cell signaling cascades. In particular, we discuss the hitherto unappreciated implication of myristoylation during myelopoiesis, innate immune response, lymphopoiesis for T cells, and the formation of the immunological synapse. Furthermore, we discuss the role of myristoylation in inducing the virological synapse during human immunodeficiency virus infection as well as its clinical implication. This review aims to summarize existing knowledge in the field and to highlight gaps in our understanding of the role of myristoylation in immune function so as to further investigate into the dynamics of myristoylation-dependent immune regulation.

A novel immune biomarker IFI27 discriminates between influenza and bacteria in patients with suspected respiratory infection.

Host response biomarkers can accurately distinguish between influenza and bacterial infection. However, published biomarkers require the measurement of many genes, thereby making it difficult to implement them in clinical practice. This study aims to identify a single-gene biomarker with a high diagnostic accuracy equivalent to multi-gene biomarkers.In this study, we combined an integrated genomic analysis of 1071 individuals with in vitro experiments using well-established infection models.We identified a single-gene biomarker, IFI27, which had a high prediction accuracy (91%) equivalent to that obtained by multi-gene biomarkers. In vitro studies showed that IFI27 was upregulated by TLR7 in plasmacytoid dendritic cells, antigen-presenting cells that responded to influenza virus rather than bacteria. In vivo studies confirmed that IFI27 was expressed in influenza patients but not in bacterial infection, as demonstrated in multiple patient cohorts (n=521). In a large prospective study (n=439) of patients presented with undifferentiated respiratory illness (aetiologies included viral, bacterial and non-infectious conditions), IFI27 displayed 88% diagnostic accuracy (AUC) and 90% specificity in discriminating between influenza and bacterial infections.IFI27 represents a significant step forward in overcoming a translational barrier in applying genomic assay in clinical setting; its implementation may improve the diagnosis and management of respiratory infection.

Revealing a 5,000-y-old beer recipe in China.

The pottery vessels from the Mijiaya site reveal, to our knowledge, the first direct evidence of in situ beer making in China, based on the analyses of starch, phytolith, and chemical residues. Our data reveal a surprising beer recipe in which broomcorn millet (Panicum miliaceum), barley (Hordeum vulgare), Job's tears (Coix lacryma-jobi), and tubers were fermented together. The results indicate that people in China established advanced beer-brewing technology by using specialized tools and creating favorable fermentation conditions around 5,000 y ago. Our findings imply that early beer making may have motivated the initial translocation of barley from the Western Eurasia into the Central Plain of China before the crop became a part of agricultural subsistence in the region 3,000 y later.

QASI: A collaboration for implementation of an independent quality assessment programme in India.

OBJECTIVE: The HIV pandemic remains a significant global health concern. Accurate determination of CD4+ T-cells in patient samples relies on reliable CD4 enumeration. The Quality Assessment and Standardization programme for Immunological measures relevant to HIV/AIDS (QASI) programme of the Public Health Agency of Canada provides clinical laboratories from resource-limited countries with a mechanism to evaluate the quality of CD4 testing and develop the implementation of an independent national External Quality Assessment (EQA) programme. This study describes how QASI helped develop the capacity for managing a sustainable national CD4 EQA programme in India. DESIGN: Supported by the Public Health Agency of Canada and Clinton Foundation HIV/AIDS Initiative, QASI engaged with the National AIDS Control Organization and the Indian National AIDS Research Institute to assist in technology transfer in preparation for the implementation/management of an independent CD4 EQA programme. Technology transfer training was provided to support corrective actions and to improve the quality of CD4 testing. Inter-laboratory variation of EQA surveys between pre- and post-skill development was compared. RESULTS: Prior to training, coefficient of variation values were 14.7% (mid-level CD4 count controls) and 39.0% (low-level). Following training, variation was reduced to 10.3% for mid-level controls and 20.0% for low-level controls. CONCLUSION: This training assisted the National AIDS Control Organization and the Indian National AIDS Research Institute in identifying the information necessary for management of an EQA programme, and developed the foundation for India to provide corrective actions for sites with challenges in achieving reliable results for CD4 enumeration. This led to a demonstrable improvement in CD4 testing quality and illustrates how country-specific training significantly improved CD4 enumeration performance for better clinical management of HIV care in India.

Quality assurance for HIV point-of-care testing and treatment monitoring assays.

In 2015, UNAIDS launched the 90-90-90 targets aimed at increasing the number of people infected with HIV to become aware of their status, access antiretroviral therapies and ultimately be virally suppressed. To achieve these goals, countries may need to scale up point-of-care (POC) testing in addition to strengthening central laboratory services. While decentralising testing increases patient access to diagnostics, it presents many challenges with regard to training and assuring the quality of tests and testing. To ensure synergies, the London School of Hygiene & Tropical Medicine held a series of consultations with countries with an interest in quality assurance and their implementing partners, and agreed on an external quality assessment (EQA) programme to ensure reliable results so that the results lead to the best possible care for HIV patients. As a result of the consultations, EQA International was established, bringing together EQA providers and implementers to develop a strategic plan for countries to establish national POC EQA programmes and to estimate the cost of setting up and maintaining the programme. With the dramatic increase in the number of proficiency testing panels required for thousands of POC testing sites across Africa, it is important to facilitate technology transfer from global EQA providers to a network of regional EQA centres in Africa for regional proficiency testing panel production. EQA International will continue to identify robust and cost-effective EQA technologies for quality POC testing, integrating novel technologies to support sustainable country-owned EQA programmes in Africa.

Reducing IRF-1 to Levels Observed in HESN Subjects Limits HIV Replication, But Not the Extent of Host Immune Activation.

Cells from women who are epidemiologically deemed resistant to HIV infection exhibit a 40-60% reduction in endogenous IRF-1 (interferon regulatory factor-1), an essential regulator of host antiviral immunity and the early HIV replication. This study examined the functional consequences of reducing endogenous IRF-1 on HIV-1 replication and immune response to HIV in natural HIV target cells. IRF-1 knockdown was achieved in ex vivo CD4(+) T cells and monocytes with siRNA. IRF-1 level was assessed using flow cytometry, prior to infection with HIV-Bal, HIV-IIIB, or HIV-VSV-G. Transactivation of HIV long terminal repeats was assessed by p24 secretion (ELISA) and Gag expression (reverse transcription-polymerase chain reaction (RT-PCR)). The expression of IRF-1-regulated antiviral genes was quantitated with RT-PCR. A modest 20-40% reduction in endogenous IRF-1 was achieved in >87% of ex vivo-derived peripheral CD4(+) T cells and monocytes, resulted in >90% reduction in the transactivation of the HIV-1 genes (Gag, p24) and, hence, HIV replication. Curiously, these HIV-resistant women demonstrated normal immune responses, nor an increased susceptibility to other infection. Similarly, modest IRF-1 knockdown had limited impact on the magnitude of HIV-1-elicited activation of IRF-1-regulated host immunologic genes but resulted in lessened duration of these responses. These data suggest that early expression of HIV-1 genes requires a higher IRF-1 level, compared to the host antiviral genes. Together, these provide one key mechanism underlying the natural resistance against HIV infection and further suggest that modest IRF-1 reduction could effectively limit productive HIV infection yet remain sufficient to activate a robust but transient immune response.

Non-Cationic Proteins Are Associated with HIV Neutralizing Activity in Genital Secretions of Female Sex Workers.

OBJECTIVE: Cationic proteins found in cervicovaginal secretions (CVS) are known to contribute to the early antiviral immune response against HIV-infection in vitro. We here aimed to define additional antiviral factors that are over-expressed in CVS from female sex workers at high risk of infection. METHODS: CVS were collected from Kenyan HIV-seronegative (n = 34) and HIV-seropositive (n = 12) female sex workers, and were compared with those from HIV-seronegative low-risk women (n = 12). The highly exposed seronegative (HESN) sex workers were further divided into those with less (n = 22) or more (n = 12) than three years of documented sex work. Cationic protein-depleted CVS were assessed for HIV-neutralizing activity by a PBMC-based HIV-neutralizing assay, and then characterized by proteomics. RESULTS: HIV neutralizing activity was detected in all unprocessed CVS, however only CVS from the female sex worker groups maintained its HIV neutralizing activity after cationic protein-depletion. Differentially abundant proteins were identified in the cationic protein-depleted secretions including 26, 42, and 11 in the HESN>3 yr, HESN<3 yr, and HIV-positive groups, respectively. Gene ontology placed these proteins into functional categories including proteolysis, oxidation-reduction, and epidermal development. The proteins identified in this study include proteins previously associated with the HESN phenotype in other cohorts as well as novel proteins not yet associated with anti-HIV activities. CONCLUSION: While cationic proteins appear to contribute to the majority of the intrinsic HIV neutralizing activity in the CVS of low-risk women, a broader range of non-cationic proteins were associated with HIV neutralizing activity in HESN and HIV-positive female sex workers. These results indicate that novel protein factors found in CVS of women with high-risk sexual practices may have inherent antiviral activity, or are involved in other aspects of anti-HIV host defense, and warrant further exploration into their mode of action.

Molecular Signatures of Immune Activation and Epithelial Barrier Remodeling Are Enhanced during the Luteal Phase of the Menstrual Cycle: Implications for HIV Susceptibility.

UNLABELLED: The variable infectivity and transmissibility of HIV/SHIV has been recently associated with the menstrual cycle, with particular susceptibility observed during the luteal phase in nonhuman primate models and ex vivo human explant cultures, but the mechanism is poorly understood. Here, we performed an unbiased, mass spectrometry-based proteomic analysis to better understand the mucosal immunological processes underpinning this observed susceptibility to HIV infection. Cervicovaginal lavage samples (n = 19) were collected, characterized as follicular or luteal phase using days since last menstrual period, and analyzed by tandem mass spectrometry. Biological insights from these data were gained using a spectrum of computational methods, including hierarchical clustering, pathway analysis, gene set enrichment analysis, and partial least-squares discriminant analysis with LASSO feature selection. Of the 384 proteins identified, 43 were differentially abundant between phases (P < 0.05, ≥2-fold change). Cell-cell adhesion proteins and antiproteases were reduced, and leukocyte recruitment (interleukin-8 pathway, P = 1.41E-5) and extravasation proteins (P = 5.62E-4) were elevated during the luteal phase. LASSO/PLSDA identified a minimal profile of 18 proteins that best distinguished the luteal phase. This profile included cytoskeletal elements and proteases known to be involved in cellular movement. Gene set enrichment analysis associated CD4(+) T cell and neutrophil gene set signatures with the luteal phase (P < 0.05). Taken together, our findings indicate a strong association between proteins involved in tissue remodeling and leukocyte infiltration with the luteal phase, which may represent potential hormone-associated mechanisms of increased susceptibility to HIV. IMPORTANCE: Recent studies have discovered an enhanced susceptibility to HIV infection during the progesterone-dominant luteal phase of the menstrual cycle. However, the mechanism responsible for this enhanced susceptibility has not yet been determined. Understanding the source of this vulnerability will be important for designing efficacious HIV prevention technologies for women. Furthermore, these findings may also be extrapolated to better understand the impact of exogenous hormone application, such as the use of hormonal contraceptives, on HIV acquisition risk. Hormonal contraceptives are the most widely used contraceptive method in sub-Saharan Africa, the most HIV-burdened area of the world. For this reason, research conducted to better understand how hormones impact host immunity and susceptibility factors important for HIV infection is a global health priority.

Presence of CD8+ T cells in the ectocervical mucosa correlates with genital viral shedding in HIV-infected women despite a low prevalence of HIV RNA-expressing cells in the tissue.

The female genital tract is a portal of entry for sexual HIV transmission and a possible viral reservoir. In this study, the ectocervical CD8+ T cell distribution was explored in situ and was related to expression of CD3 and HLA-DR and presence of HIV RNA. For this purpose, ectocervical tissue samples and genital secretions were collected from HIV-seropositive (HIV+) Kenyan female sex workers (FSWs) (n = 20), HIV-seronegative (HIV-) FSWs (n = 17), and HIV(-) lower-risk women (n = 21). Cell markers were assessed by in situ staining and by quantitative PCR. HIV RNA expression in tissue was analyzed by in situ hybridization, and viral shedding was assessed by quantitative PCR. The HIV+ FSW group had a higher amount of total cells and CD8+, CD3+, and HLA-DR+ cells compared with the HIV(-)FSW group and HIV- lower-risk women. The majority of CD8+ cells were CD3+ T cells, and the numbers of CD8+ cells correlated significantly with plasma and cervical viral load. HIV RNA expression in situ was found in 4 of the 20 HIV+FSW women but did not correlate with cervical or plasma viral load. Thus, the HIV+ women displayed high numbers of CD8+, CD3+, and HLA-DR+ cells, as well as a limited number of HIV RNA+ cells, in their ectocervical mucosa; hence, this localization cannot be neglected as a potential viral reservoir. The elevated levels of CD8+ T cells may play a role in the immunopathogenesis of HIV in the female genital tract.

The 1.59Å resolution structure of the minor pseudopilin EpsH of Vibrio cholerae reveals a long flexible loop.

The type II secretion complex exports folded proteins from the periplasm to the extracellular milieu. It is used by the pathogenic bacterium Vibrio cholerae to export several proteins, including its major virulence factor, cholera toxin. The pseudopilus is an essential component of the type II secretion system and likely acts as a piston to push the folded proteins across the outer membrane through the secretin pore. The pseudopilus is composed of the major pseudopilin, EpsG, and four minor pseudopilins, EpsH, EpsI, EpsJ and EpsK. We determined the x-ray crystal structure of the head domain of EpsH at 1.59Å resolution using molecular replacement with the previously reported EpsH structure, 2qv8, as the template. Three additional N-terminal amino acids present in our construct prevent an artifactual conformation of residues 160-166, present in one of the two monomers of the 2qv8 structure. Additional crystal contacts stabilize a long flexible loop comprised of residues 104-135 that is more disordered in the 2qv8 structure but is partially observed in our structure in very different positions for the two EpsH monomers in the asymmetric unit. In one of the conformations the loop is highly extended. Modeling suggests the highly charged loop is capable of contacting EpsG and possibly secreted protein substrates, suggesting a role in specificity of pseudopilus assembly or secretion function.

The role of serpin and cystatin antiproteases in mucosal innate immunity and their defense against HIV.

Antiproteases play diverse roles in nature, from regulating protease activity to innate defense against microorganisms. Recently, antiproteases have been shown to play important roles in HIV pathogenesis including, inhibiting HIV binding and replication and reducing activation and inflammation of susceptible cells. They have also been implicated as one of the initial host responders, in plasma, to control replication of HIV. More recently, antiproteases expressed at the mucosal surface have been linked to reduced susceptibility to HIV infection in HIV-exposed sero-negative individuals. These factors are expressed in the epithelial layer of the female genital tract, thus at the frontline of defense against mucosal infection. This review focuses on the specific antimicrobial roles of antiproteases, focusing on serpins and cystatins, with an emphasis on their known and potential roles in HIV infection. Their potential as therapeutic interventions to combat HIV is also discussed.

Immune quiescence: a model of protection against HIV infection.

Aberrant immune activation is a strong correlate of HIV disease progression, but little is known about how immune activation alters susceptibility to HIV infection. Susceptibility to HIV infection varies between individuals, but the immunological determinants of HIV transmission are not well understood. Here, we present evidence from studies of HIV transmission in the context of clinical trials and HIV-exposed seronegative (HESN) cohorts that implicates elevated immune activation as a risk factor for acquiring HIV. We propose a model of protection from infection based on a phenotype of low baseline immune activation referred to as immune quiescence. Immune quiescence is evidenced by reduced expression of T cell activation markers, low levels of generalized gene transcription and low levels of proinflammatory cytokine and chemokine production in the periphery and genital mucosa of HESN. Since HIV preferentially replicates in activated CD4+ T cells, immune quiescence may protect against infection by limiting HIV target cell availability. Although the determinants of immune quiescence are unclear, several potential factors have been identified that may be involved in driving this phenotype. HESN were shown to have elevated proportions of regulatory T cells (Tregs), which are known to suppress T cell activation. Likewise, proteins involved in controlling inflammation in the genital tract have been found to be elevated in HESN. Furthermore, expression of interferon regulatory factor 1 (IRF-1) is reduced in HESN as a consequence of genetic polymorphisms and differential epigenetic regulation. Since IRF-1 is an important regulator of immune responses, it may play a role in maintaining immune quiescence. Based on this model, we propose a novel avenue for HIV prevention targeted based on reducing host mucosal immune activation.

Stable CD4 expression and local immune activation in the ectocervical mucosa of HIV-infected women.

Studies using genital tissue samples from HIV-infected women might provide important information about HIV susceptibility and transmission. In this study, ectocervical biopsies were obtained from 20 HIV-seropositive (HIV(+)) Kenyan female sex workers (FSW) and 20 HIV-seronegative lower risk (HIV(-) LR) women. To control for the impact of sex work, 20 HIV(-) FSW were also recruited. Immune molecules were assessed in situ by immunohistochemistry and for mRNA expression by quantitative PCR. The HIV(+) women were reportedly infected for a median of 3 y (1-21 y), with a median viral load of 11,735 copies/ml (20-648,000 copies/ml). These women had significantly lower CD4 blood cell counts than the HIV(-) LR women but comparable levels of CD4 expression in ectocervix. Whereas cellular markers were similar between the HIV(+) group and the HIV(-) LR women, the HIV-binding molecules CCR5, dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin, and mannose receptor as well as the inflammatory markers CD69, IFN-γ, IL-6, and IL-22 were significantly upregulated in the HIV(+) group. As compared with the HIV(-) FSW women, the HIV(+) women had significantly upregulated levels of CD4, CD3, CCR5, Langerin, dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin, and mannose receptor as well as inflammatory cytokines. The CD4 cell depletion previously seen in the gut mucosa of HIV-infected individuals was thus not observed in the ectocervical mucosa. Stable CD4 cell expression and local immune activation in the lower female genital tract may promote viral replication and genital shedding and increase the risk of sexual HIV transmission.