Role of polymorphonuclear leukocytes in resolution of HSV-2 infection of the mouse vagina

Morphology of the immune cells in the wall of the human uterine tube and their possible impact on reproduction-uterine tube as a possible immune privileged organ

The uterine tube, as well as other parts of the upper female reproductive system, is immunologically unique in its requirements for tolerance to allogenic sperm and semi-allogenic embryos, yet responds to an array of sexually transmitted pathogens. To understand this dichotomy, there is a need to understand the functional morphology of immune cells in the wall of the uterine tube. Thus, we reviewed scientific literature regarding immune cells and the human uterine tube by using the scientific databases. The human uterine tube has a diverse population of immunocompetent cells representing both the innate and adaptive immune systems. We describe in detail the possible roles of cells of the mononuclear phagocyte system (macrophages and dendritic cells), T and B lymphocytes, natural killer cells, neutrophils and mast cells in association with the reproductive functions of uterine tubes. We are also discussing about the possible "immune privilege" of the uterine tube, as another mechanism to tolerate sperm and embryo without eliciting an inflammatory immune response. In uterine tube is not present an anatomical blood-tissue barrier between antigens and circulation. However, the immune cells of the uterine tube probably represent a type of "immunological barrier," which probably includes the uterine tube among the immunologically privileged organs. Understanding how immune cells in the female reproductive tract play roles in reproduction is essential to understand not only the mechanisms of gamete transport and fertilization as well as embryo transport through the uterine tube, but also in improving results from assisted reproduction.

A sustained type I IFN-neutrophil-IL-18 axis drives pathology during mucosal viral infection

Neutrophil responses against pathogens must be balanced between protection and immunopathology. Factors that determine these outcomes are not well-understood. In a mouse model of genital herpes simplex virus-2 (HSV-2) infection, which results in severe genital inflammation, antibody-mediated neutrophil depletion reduced disease. Comparative single-cell RNA-sequencing analysis of vaginal cells against a model of genital HSV-1 infection, which results in mild inflammation, demonstrated sustained expression of interferon-stimulated genes (ISGs) only after HSV-2 infection primarily within the neutrophil population. Both therapeutic blockade of IFNα/β receptor 1 (IFNAR1) and genetic deletion of IFNAR1 in neutrophils concomitantly decreased HSV-2 genital disease severity and vaginal IL-18 levels. Therapeutic neutralization of IL-18 also diminished genital inflammation, indicating an important role for this cytokine in promoting neutrophil-dependent immunopathology. Our study reveals that sustained type I interferon (IFN) signaling is a driver of pathogenic neutrophil responses and identifies IL-18 as a novel component of disease during genital HSV-2 infection.

IL-36γ Is a Key Regulator of Neutrophil Infiltration in the Vaginal Microenvironment and Limits Neuroinvasion in Genital HSV-2 Infection

HSV-2 is a neurotropic virus that causes a persistent, lifelong infection that increases risk for other sexually transmitted infections. The vaginal epithelium is the first line of defense against HSV-2 and coordinates the immune response through the secretion of immune mediators, including the proinflammatory cytokine IL-36γ. Previously, we showed that IL-36γ treatment promoted transient polymorphonuclear cell infiltration to the vaginal cavity and protected against lethal HSV-2 challenge. In this report, we reveal that IL-36γ specifically induces transient neutrophil infiltration but does not impact monocyte and macrophage recruitment. Using IL-36γ^-/- mice in a lethal HSV-2 challenge model, we show that neutrophil counts are significantly reduced at 1 and 2 d postinfection and that KC-mediated mature neutrophil recruitment is impaired in IL-36γ^-/- mice. Additionally, IL-36γ^-/- mice develop genital disease more rapidly, have significantly reduced survival time, and exhibit an increased incidence of hind limb paralysis that is linked to productive HSV-2 infection in the brain stem. IL-36γ^-/- mice also exhibit a significant delay in clearance of the virus from the vaginal epithelium and a more rapid spread of HSV-2 to the spinal cord, bladder, and colon. We further show that the decreased survival time and increased virus spread observed in IL-36γ^-/- mice are not neutrophil-dependent, suggesting that IL-36γ may function to limit HSV-2 spread in the nervous system. Ultimately, we demonstrate that IL-36γ is a key regulator of neutrophil recruitment in the vaginal microenvironment and may function to limit HSV-2 neuroinvasion.

The type I interferon receptor is not required for protection in the Chlamydia muridarum and HSV-2 murine super-infection model

Chlamydia trachomatis/HSV-2 vaginal co-infections are seen clinically, suggesting that these sexually transmitted pathogens may interact. We previously established an intravaginal Chlamydia muridarum/HSV-2 super-infection model and observed that chlamydial pre-infection protects mice from a subsequent lethal HSV-2 challenge. However, the mechanism of protection remains unknown. The type I interferon, IFN-β, binds to the type I interferon receptor (IFNR), elicits a host cellular antiviral response and inhibits HSV replication in vitro and in vivo. Previous studies have demonstrated that C. muridarum infection stimulates genital tract (GT) IFN-β production; therefore, we hypothesized that chlamydial pre-infection protects mice from HSV-2 challenge via the IFN-β/IFNR-induced antiviral response. To test this prediction, we quantified IFN-β levels in vaginal swab samples. Detection of IFN-β in C. muridarum singly infected, but not in mock-infected animals, prompted the use of the super-infection model in IFNR knockout (IFNR^−/−) mice. We observed that C. muridarum pre-infection reduces HSV-2-induced mortality by 40% in wild-type mice and by 60% IFNR^−/− mice. Severity of HSV-2 disease symptoms and viral shedding was also similarly reduced by C. muridarum pre-infection. These data indicate that, while chlamydial infection induces GT production of IFN-β, type I IFN-induced antiviral responses are likely not required for the observed protective effect.

Antiviral Action of Diphenyl Diselenide on Herpes Simplex Virus 2 Infection in Female BALB/c Mice

Diphenyl diselenide, (PhSe)2 , is an organoselenium compound with pharmacological actions mostly related to antioxidant and anti-inflammatory properties. The study investigated its antiviral and virucidal actions against herpes simplex virus 2 (HSV-2) infection in vitro and in a vaginal infection model in mice. The plaque reduction assay indicated that (PhSe)2 showed virucidal and antiviral actions reducing infectivity in 70.8% and 47%, respectively. The antiviral action of (PhSe)2 against HSV-2 vaginal infection was performed by infecting mice (10(5)  PFU/ml(-1) ) at day 6. The treatment with (PhSe)2 (5 mg/kg/day, intragastric [i.g.]) followed 5 days before and for more 5 days after infection. The extravaginal lesion score was evaluated from days 6 to 10. At day 11, animals were killed, and histological evaluation, determination of viral load, and TNF-α and IFN-γ levels were performed in supernatants of homogenized vaginal tissue. The levels of reactive species (RS), protein carbonyl, non-protein thiols (NPSH), nitrate/nitrite (NOx), and malondialdehyde (MDA), and the activities of myeloperoxidase (MPO), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) were determined. (PhSe)2 reduced the histological damage, extravaginal lesion scores, the viral load of vaginal tissue, and the activity of MPO, but increased the levels of TNF-α, IFN-γ. (PhSe)2 attenuated the increase of RS, MDA, NOx levels and the activity of GR caused by infection. (PhSe)2 also attenuated the reduction of NPSH content and the inhibition of CAT, SOD, and GPx activities. The antiviral action of (PhSe)2 against HSV-2 infection was related to its immunomodulatory, antioxidant, and anti-inflammatory properties. J. Cell. Biochem. 117: 1638-1648, 2016. © 2015 Wiley Periodicals, Inc.

Cervico-vaginal immunoglobulin G levels increase post-ovulation independently of neutrophils

The prevalence of sexually transmitted infections (STIs) is often higher in females than in males. Although the reproductive cycle profoundly modulates local immunity in the female reproductive tract (FRT) system, significant gaps in our knowledge of the immunobiology of the FRT still exist. An intriguing and frequently observed characteristic of the FRT is the predominant presence of immunoglobulin (Ig) G in cervico-vaginal secretions. We show here that in the mouse, IgG accumulation was enhanced approximately 5-fold post-ovulation, and was accompanied by an influx of neutrophils into the FRT. To determine whether these two events were causally related, we performed short-term neutrophil depletion experiments at individual stages throughout the estrous cycle. Our results demonstrate that neutrophils were not necessary for cycle-dependent tissue remodeling and cycle progression and that cycle-dependent IgG accumulation occurred independent of neutrophils. We thus conclude that neutrophil influx and IgG accumulation are independent events that occur in the FRT during the reproductive cycle.

HSV-2 regulates monocyte inflammatory response via the Fas/FasL pathway

Monocytic cells represent important cellular elements of the innate and adaptive immune responses in viral infections. We assessed the role of Fas/FasL in promoting monocyte apoptosis during HSV-2 infection by using an in vitro model based on the murine RAW 264.7 monocytic cell line and an in vivo murine model of HSV-2 infection applied to C57BL6, MRL-Fas^lpr/J (Fas−/−) and C3-Fasl^gld/J (FasL−/−) mice. HSV-2 infection of the monocytic cell line led to early induction of apoptosis, with no protective expression of anti-apoptotic Bcl-2. HSV-2 infected monocytes up-regulated Fas and FasL expression early during in vitro infection but were susceptible to Fas induced apoptosis. The vaginal monocytes in the HSV-2 murine model of infection up-regulated FasL expression and were susceptible to Fas induced apoptosis. HSV-2 infection of Fas and FasL- deficient mice led to decreased apoptosis of monocytes and impaired recruitment of NK, CD4+ and CD8+ T cells within the infection sites. The vaginal lavages of HSV-2 infected Fas and FasL- deficient showed decreased production of CXCL9, CXCL10 and TNF-α in comparison to HSV-2 infected wild-type mice strain. The decreased recruitment of immune competent cells was accompanied by delayed virus clearance from the infected tissue. Triggering of the Fas receptor on HSV-2 infected monocytes in vitro up-regulated the expression of CXCL9 chemokines and the cytokine TNF-α. Our study provides novel insights on the role of Fas/FasL pathway not only in apoptosis of monocytes but also in regulating local immune response by monocytes during HSV-2 infection.

Absence of CCR5 increases neutrophil recruitment in severe herpetic encephalitis

Background

The neuroinflammatory response aimed at clearance of herpes simplex virus-1 (HSV-1) plays a key role in the pathogenesis of neuroaxonal damage in herpetic encephalitis. Leukocytes activated in an adaptive immune response access brain tissue by passing through the blood–brain barrier. The chemokine CCL5/RANTES is involved in recruitment of these cells to the brain acting via the receptors CCR1, CCR3 and mainly CCR5. Here, we evaluated the role of CCR5 on traffic of leukocytes in the brain microvasculature, cellular and cytokines profile in a severe form of herpetic encephalitis.

Results

Wild type and mice lacking CCR5 (CCR5^-/-) were inoculated intracerebrally with 10⁴ PFU of neurotropic HSV-1. We evaluated the traffic of leukocytes in the brain microvasculature using intravital microscopy and the profile of cytokines by Enzyme-Linked Immunosorbent Assay at 1 day post infection. Flow cytometry and histopathological analyses were also carried out in brain tissue. Absence of CCR5 leads to lower viral load and an increased leukocyte adhesion in brain microvasculature, predominantly of neutrophils (CD11⁺ Ly6G⁺ cells). Moreover, there was a significant increase in the levels of MIP-1/CCL2, RANTES/CCL5, KC/CXCL1 and MIG/CXCL9 in the brain of infected CCR5^-/- mice.

Conclusions

These results suggest that the absence of CCR5 may boost the immune response with a high neutrophil recruitment which most likely helps in viral clearance. Nonetheless, the elevated immune response may be detrimental to the host.

HSV-1 strain McKrae is more neuroinvasive than HSV-1 KOS after corneal or vaginal inoculation in mice

Strains of HSV-1 have been noted to vary in their pathogenesis. We compared the replication of strains KOS and McKrae in mice by two routes of infection, ocular and vaginal. Peripheral replication of KOS was similar (cornea) or attenuated over time (vagina) compared with McKrae; however, McKrae replicated in the nervous system to significantly higher levels than KOS after inoculation by either route. Host genetic background strongly influenced the capacity for virus entry into the nervous system from the vagina. KOS and McKrae replicated equivalently after intracranial inoculation, indicating that McKrae's pathogenic phenotype is linked to neuroinvasiveness rather than neurovirulence.

Role of Fas/FasL in regulation of inflammation in vaginal tissue during HSV-2 infection

To assess the role of Fas in lesion development during genital HSV-2 infection, we used a well-established HSV-2 murine model applied to MRL-Fas(lpr)/J (Fas-/-) and C3-Fasl(gld)/J (FasL-/-) C57BL6 mice. In vitro infection of murine keratinocytes and epithelial cells was used to clarify molecular details of HSV-2 infection. Despite upregulation of Fas and FasL, HSV-2-infected keratinocytes and epithelial cells showed a moderate level of apoptosis due to upregulated expression of the anti-apoptotic factors Bcl-2, Akt kinase and NF-κB. Inflammatory lesions within the HSV-2-infected epithelium of C57BL6 mice consisted of infected cells upregulating Fas, FasL and Bcl-2, uninfected cells upregulating Fas and neutrophils expressing both Fas and FasL. Apoptosis was detected in HSV-2-infected cells and to even higher extent in non-infected cells surrounding HSV-2 infection sites. HSV-2 infection of Fas- and FasL-deficient mice led to increased apoptosis and stronger recruitment of neutrophils within the infection sites. We conclude that the Fas pathway participates in regulation of inflammatory response in the vaginal epithelium at the initial stage of HSV-2 infection.

Excess neutrophil infiltration during cytomegalovirus brain infection of interleukin-10-deficient mice

Wild-type mice control murine cytomegalovirus (MCMV) brain infection, but identical infection is lethal to animals deficient in interleukin (IL)-10. Here, we report that MCMV-infected IL-10 knockout (KO) mice displayed a marked increase in neutrophil infiltration into the infected, IL-10-deficient brain when compared to wild-type animals. Enhanced microglial cell activation, determined by MHC class II up-regulation, overexpression of CXCL2, and elevated P-selectin mRNA levels were observed. In vivo blocking of CXCL2 attenuated neutrophil infiltration and significantly improved the outcome of infection. Collectively, these data indicate that the absence of IL-10 results in pathologic neutrophil infiltration into MCMV-infected brains.

Herpes simplex virus (HSV)-specific T cells activated in the absence of IFN-gamma express alternative effector functions but are not protective against genital HSV-2 infection

Interferon gamma (IFNgamma) is important for immune resistance to herpes simplex virus (HSV) infection. To examine the influence of IFNgamma on the development of HSV-specific immune responses and test for IFNgamma-independent adaptive immune mechanisms of protection, IFNgamma-deficient mice (IFNgamma(-/-)) were immunized with thymidine kinase-deficient HSV-2 (HSV-2 333tk(-)). HSV-specific cellular and humoral responses were elicited in immunized IFNgamma(-/-) mice resulting in increased resistance relative to non-immune C57BL/6J (B6) mice following challenge with fully virulent HSV-2. CD8(+) T cells from IFNgamma(-/-) mice displayed cytotoxic activity and secreted TNFalpha. HSV-specific CD4(+) T cells from immunized IFNgamma(-/-) mice secreted IL-4, TNFalpha, and IL-17, but unlike T cells from HSV-immune B6 mice, could not clear virus from genital tissue following adoptive transfer. HSV-immune IFNgamma(-/-) mice produced predominantly IgG(1) HSV-specific antibodies while immune B6 mice produced predominantly IgG(2c) antibodies. Transfer of equivalent amounts of HSV-specific antibodies from either strain to naïve mice imparted equivalent early resistance against infection of the genital epithelia. However, protection against neurological symptoms mediated by immune B6 antibodies was superior late in infection. Taken together, these results demonstrate that the limited resistance of HSV-immune IFNgamma(-/-) mice to HSV-2 infection resulted from the action of HSV-specific Ab rather than IFNgamma-independent effector functions of T cells. Further, protection against neurological manifestations of HSV-2 infection was superior in mice receiving Ab from immune B6 mice suggesting that Ab-mediated protective mechanisms involving IFNgamma-induced IgG subclasses were more effective once virus had spread to neural tissues.

Increased detection of clue cells in smears from cervical intraepithelial lesions with reduced expression of COX-2

The relation between the detection of clue cells in cervical smears of women with CIN and the expression of COX-2 in these lesions were determined. Samples from 228 women, treated due to CIN and who underwent cervical conization, were obtained. Hybrid Capture II and Pap smear samples were collected immediately before performing conization. Pathological diagnoses were 11 (5%) normal cervix, 35 (15%) CIN1, 31 (14%) CIN2, and 151 (66%) CIN3. COX-2 immunoreactivity grading on the pathological specimens was based on the German ImmunoReactive score. In cervical smears, 20 fields (40x) were examined, each of them with a minimum count of 10 epithelial cells. When 20% or more of clue cells were detected the sample was considered positive for clue cells. The prevalence of clue cells was similar across histological strata (P = 0.42). Although the expression of COX-2 did not differ in lesions with varying severities (P = 0.24), there was a negative association between the expression of COX-2 and the presence of clue cells in Pap smear (OR = 0.4; 95% CI = 0.2-0.9): only 12% of women with moderate and strong expression of COX-2 had clue cells in their smears, contrasted to 22% of those with negative and weak expression of COX-2. HPV infection was associated in a borderline manner to the expression of COX-2 (P = 0.04; OR = 2.3 95% CI = 1.0-5.4). The reduced expression of COX-2 in CIN specimens may suggest that clue cells interfere with the inflammatory component of the carcinogenic process that lead to CIN.

Chemokines and Chemokine Receptors Critical to Host Resistance following Genital Herpes Simplex Virus Type 2 (HSV-2) Infection

HSV-2 is a highly successful human pathogen with a remarkable ability to elude immune detection or counter the innate and adaptive immune response through the production of viral-encoded proteins. In response to infection, resident cells secrete soluble factors including chemokines that mobilize and guide leukocytes including T and NK cells, neutrophils, and monocytes to sites of infection. While there is built-in redundancy within the system, chemokines signal through specific membrane-bound receptors that act as antennae detailing a chemical pathway that will provide a means to locate and eliminate the viral insult. Within the central nervous system (CNS), the temporal and spatial expression of chemokines relative to leukocyte mobilization in response to HSV-2 infection has not been elucidated. This paper will review some of the chemokine/chemokine receptor candidates that appear critical to the host in viral resistance and clearance from the CNS and peripheral tissue using murine models of genital HSV-2 infection.

Leukotriene B4-mediated release of antimicrobial peptides against cytomegalovirus is BLT1 dependent

Leukotriene B4 (LTB(4)) is a potent lipid mediator of inflammation that possesses antiviral activities. Here we provide evidence that LTB(4)-mediated defense against in vitro cytomegalovirus (CMV) infection of human leukocytes involves activation of the high-affinity LTB(4) receptor (BLT1) and neutrophil degranulation. Treatment of CMV-infected peripheral blood leukocytes with LTB(4) (10 nM) leads to a significant reduction in viral titers. This activity involves neutrophil activation through the BLT1 receptor, because no reduction in viral titers was observed after neutrophil depletion from cellular preparation or when leukocytes were pretreated with the BLT1 antagonist U75,302. Direct stimulation of neutrophils with LTB(4) (in the presence or absence of CMV) leads to the release of myeloperoxidase, alpha-defensins, eosinophil-derived neurotoxin, and the human cathelicidin LL-37 in a BLT1-dependent manner. LTB(4) does not act exclusively on the secretion of preformed antimicrobial peptides, but also acts on the synthesis of selected peptides as reflected by the increase in transcriptional levels of eosinophil-derived neurotoxin (EDN) and LL-37 in LTB(4)-treated neutrophils. Treatment of cell cultures with neutralizing antibodies directed against alpha-defensins, EDN, and LL-37 significantly reduces the antiviral effect of LTB(4), suggesting that LTB(4) may act through the release of antimicrobial peptides. Ex vivo experiments using LTB(4)-treated neutrophils from peritoneal washing of wild-type and BLT1 knockout mice further supported the role played by antimicrobial peptides in LTB(4)-mediated antiviral activity toward CMV. These results provide evidence of a mechanism by which LTB(4) induces host defense against viral infection.

CXCR2 is required for neutrophil recruitment to the lung during influenza virus infection, but is not essential for viral clearance

Neutrophils traffic to the lungs in large numbers during influenza virus infection. Although the ability of these cells to respond to numerous chemotactic stimuli has been described in other systems, the chemokine receptors mediating recruitment of neutrophils to the lungs during influenza virus infection and the role of this cell type in viral clearance are currently undefined. In the present study, we used CXCR2(/) mice to investigate the role of the chemokine receptor CXCR2 in neutrophil recruitment to the lungs during influenza virus infection and to determine the role of neutrophils in viral clearance. We infected CXCR2(/) or wild-type mice with influenza and assessed the level of inflammation, the cellular composition of the inflammatory infiltrate, and viral titers in the lungs. Absence of CXCR2 ablated neutrophil recruitment to the lungs, but had no effect on peak viral titers or on the kinetics of viral clearance. Thus, it appears that CXCR2 is the major receptor mediating neutrophil trafficking to the lung during influenza virus infection, but that neutrophils do not play an essential role in viral clearance.

Antibody-mediated protection against genital herpes simplex virus type 2 disease in mice by Fc gamma receptor-dependent and -independent mechanisms

The ability of antibody (Ab) to modulate HSV pathogenesis is well recognized but the mechanisms by which HSV-specific IgG antibodies protect against genital HSV-2 disease are not well understood. The requirement for Ab interactions with Fcgamma receptors (FcgammaR) in protection was examined using a murine model of genital HSV-2 infection. IgG antibodies isolated from the serum of HSV-immune mice protected normal mice against HSV-2 disease when administered prior to genital HSV-2 inoculation. However, protection was significantly diminished in recipient mice lacking the gamma chain subunit utilized in FcgammaRI, FcgammaRIII, FcgammaRIV and FcepsilonRI receptors and in normal mice depleted of Gr-1(+) immune cell populations known to express FcgammaR, suggesting protection was largely mediated by an FcgammaR-dependent mechanism. To test whether neutralizing Ab might provide superior protection, a highly neutralizing HSV glycoprotein D (gD)-specific monoclonal antibody (mAb) was utilized. Similar to results with HSV-specific polyclonal IgG, administration of the gD-specific mAb did not prevent initial infection of the genital tract but resulted in lower virus loads in the vaginal epithelium and provided significant protection against disease and acute infection of the sensory ganglia; however, this protection was independent of host FcgammaR expression and was manifest in mice depleted of Gr-1(+) immune cells. Together, these data demonstrate that substantial Ab-mediated protection against genital HSV-2 disease could be achieved by either FcgammaR-dependent or -independent mechanisms. These studies suggest that HSV vaccines might need to elicit multiple, diverse antibody effector mechanisms to achieve optimal protection.

Human Fallopian Tube Neutrophils – A Distinct Phenotype from Blood Neutrophils

PROBLEM

The role of neutrophils in the human Fallopian tube (FT) is unknown. In order to provide insights into their functions in the FT, we systematically compared neutrophils from normal FT and peripheral blood (PB).

METHOD OF STUDY

Flow cytometric analysis of surface receptors, granule proteins, and intracellular cytokines expressed by neutrophils from enzymatically dispersed FT and PB was performed.

RESULTS

Fallopian tube neutrophils expressed significantly higher levels of CD64, human class II histocompatibility antigen DR (HLA-DR), gamma-interferon, and vascular endothelial growth factor than those from PB. Fewer FT neutrophils expressed IL-8 receptors compared to PB, while more expressed the receptor for the bacterial-derived chemoattractant formyl-Met-Leu-Phe (fMLP). The number of FT neutrophils containing the granule proteins matrix metalloproteinase-9, lactoferrin, and myeloperoxidase was decreased versus PB.

CONCLUSION

Fallopian tube neutrophils exhibit a phenotype distinct from PB neutrophils, suggesting functional activation of innate immune defense in the female reproductive tract as well as a potential role in maintaining normal FT physiology.

Role of mucosal immunity in preventing genital herpes infection

The female genital tract is immunologically unique because it must be tolerant to spermatozoa, pregnancy, and vaginal flora, but also protect the host from pathogen challenge. The mucosal response to herpes simplex viruses (HSV), a major cause of genital ulcerative disease and critical co-factor in the HIV/AIDS epidemic, is complex and consists of the normally acidic vaginal environment, constitutively secreted and induced antimicrobial peptides, complement, and cellular responses mediated by epithelial and immune cells. This review summarizes our current understanding of the mucosal response to HSV focusing on those factors that may prevent initial infection. Understanding how each of these components contribute to innate immunity, mechanisms of antiviral activity, and whether the virus has evolved strategies to evade their effects may lead to the development of novel vaginal microbicides.

Clearance of herpes simplex virus type 2 by CD8+ T cells requires gamma interferon and either perforin- or Fas-mediated cytolytic mechanisms

The T-cell-mediated resolution of herpes simplex virus type 2 (HSV-2) genital infections is not fully understood. In these studies, the mechanisms by which CD8+ T cells clear virus from the genital epithelium were examined. Ovalbumin (OVA)-specific CD8+ T cells from OT-I transgenic mice cleared a thymidine kinase-deficient, ovalbumin-expressing HSV-2 virus (HSV-2 tk- OVA) from the genital epithelium of recipient mice, and clearance was abrogated by in vivo neutralization of gamma interferon (IFN-gamma). Further, CD8+ OT-I T cells deficient in IFN-gamma were unable to clear HSV-2 tk- OVA from the vaginal epithelium. The requirement for cytolytic mechanisms in HSV-2 tk- OVA clearance was tested in radiation chimeras by adoptive transfer of wild-type or perforin-deficient OT-I T cells to irradiated Fas-defective or wild-type recipients. Although a dramatic decrease in viral load was observed early after challenge with HSV-2 tk- OVA, full resolution of the infection was not achieved in recipients lacking both perforin- and Fas-mediated cytolytic pathways. These results suggest that IFN-gamma was responsible for an early rapid decrease in HSV-2 virus titer. However, either perforin- or Fas-mediated cytolytic mechanisms were required to achieve complete clearance of HSV-2 from the genital epithelium.

Protective immunity to genital herpes simplex [correction of simpex] virus type 2 infection is mediated by T-bet

We show, for the first time, that the transcription factor T-bet, which is implicated in IFN-gamma production, is required for the induction of vaccine-induced antiviral immune protection. T-bet was found to be important in both the innate and acquired immune protection against genital HSV-2 infection. T-bet(-/-) and T-bet(+/+) mice were infected vaginally with HSV-2 and examined daily for disease and mortality. T-bet(-/-) mice had significantly higher virus titers than T-bet(+/+) mice following a primary HSV-2 infection, and succumbed significantly earlier to the infection. This result was associated with an impaired NK cell cytotoxic capacity and NK cell-mediated IFN-gamma production in the T-bet(-/-) mice. To assess the induction of acquired antiviral immune protection, mice were vaccinated with an attenuated virus before infection. Vaccinated T-bet(-/-) mice could not control viral replication following an HSV-2 challenge and had significantly higher virus titers and mortality rates than vaccinated T-bet(+/+) mice that remained healthy. The impaired acquired immune protection in T-bet(-/-) mice was associated with a significantly decreased HSV-2-specific delayed-type hypersensitivity response and a significantly reduced HSV-2-specific IFN-gamma production from CD4(+) T cells. However, T-bet deficiency did not impair either the IFN-gamma production or the cytotoxic capacity of HSV-2-specific CD8(+) T cells. We conclude that T-bet plays a crucial role in both the innate defense and the generation of vaccine-induced immunity against genital HSV-2 infection in mice.

A proinflammatory peptide from herpes simplex virus type 2 glycoprotein G affects neutrophil, monocyte, and NK cell functions

We have identified a synthetic peptide derived from the secreted portion of HSV type 2 glycoprotein G, denoted gG-2p20, which has proinflammatory properties in vitro. The gG-2p20 peptide, corresponding to aa 190-205 of glycoprotein G-2, was a chemoattractant for both monocytes and neutrophils in a dose-dependent fashion, and also induced the release of reactive oxygen from these cells. The receptor mediating the responses was identified as the formyl peptide receptor. The gG-2p20-induced activation of phagocytes had a profound impact on NK cell functions. The reactive oxygen species produced by gG-2p20-activated phagocytes both inhibited NK cell cytotoxicity and accelerated the apoptotic cell death in NK cell-enriched lymphocyte populations. Hence, we have for the first time been able to identify a potential function of the secreted portion of HSV-2 glycoprotein G. We propose that the proinflammatory gG-2p20 peptide identified could contribute to a reduced function and viability of NK cells during HSV-2 infection due to its ability to recruit and activate phagocytic cells.

Bacterial vaginosis - a microbiological and immunological enigma. Review article

The development of bacterial vaginosis (BV) among women of childbearing age and the resulting quantitative and qualitative shift from normally occurring lactobacilli in the vagina to a mixture of mainly anaerobic bacteria is a microbiological and immunological enigma that so far has precluded the formulation of a unifying generally accepted theory on the aetiology and clinical course of BV. This critical review highlights some of the more important aspects of BV research that could help in formulating new basic ideas respecting the biology of BV, not least the importance of the interleukin mediators of local inflammatory responses and the bacterial shift from the normally occurring lactobacilli species: L. crispatus, L. gasseri, L. jensenii, and L. iners to a mixed flora dominated by anaerobic bacteria.

Early inhibition of nitric oxide production increases HSV-1 intranasal infection

Here, we studied the role of nitric oxide (NO) production during the first steps of the respiratory infection of BALB/c mice with herpes simplex virus type 1 (HSV-1), strain F. Nitric oxide synthase II (NOS-II) mRNA and protein were detected by reverse transcription (RT)-PCR and dot blot, respectively in samples of lungs and turbinates early post-infection (p.i.). Immunohistochemical analysis revealed pulmonar macrophages and PMN expressing NOS-II in the lungs of infected animals. Animals intranasally treated with aminoguanidine (AG), a NOS inhibitor, during the first steps of infection, showed a dose-dependent increase in pneumonitis compared to controls. Viral titres in turbinates, lungs, and brains were higher in AG treated mice. Finally, histopathology studies revealed a stronger inflammation in eyes, and lungs of these animals. Taken together, these results suggest a role of NO in controlling primary HSV intranasal infection.

Innate immunity to herpes simplex virus type 2

Herpes simplex virus type 2 (HSV-2) is responsible for most cases of genital herpes and also can cause fatal disseminated disease in perinatally infected newborns. Sexually transmitted infections initiate in the skin or mucosa and quickly spread into peripheral nerves to establish latency. Innate immunity, the first line of defense during both primary and recurrent infection, is essential during this period of acute infection to limit initial viral replication and to facilitate an appropriate adaptive immune response. The innate immune response consists of a complex multilayered system of mechanical and secreted defenses, immediate chemokine and IFN responses, and rapidly recruited cellular defenses. HSV has devised equally elaborate strategies to evade or interfere with innate immunity. This review summarizes our current understanding of the innate immune responses to HSV-2 and the mechanisms by which HSV-2 can overcome these barriers. Newly emerging links between products of innate responses and the development of adaptive immune responses are also discussed.

Blocking CC chemokine receptor (CCR) 1 and CCR5 during herpes simplex virus type 2 infection in vivo impairs host defence and perturbs the cytokine response

Elimination of viral infections is dependent on rapid recruitment of leucocytes to infected areas. Chemokines constitute a class of cytokines that regulate migration of leucocytes to sites of infection. In this work, the expression and function of CC chemokine receptor (CCR)1 and CCR5 and their ligands during a generalized herpes simplex virus type 2 (HSV-2) infection in mice were studied. Many CCR1 and CCR5 ligands were expressed in infected organs after intraperitoneal infection. In particular, CC chemokine expression in the liver preceded the expression of CCR1 and CCR5, suggesting recruitment of cells bearing these receptors, which correlated with a decrease in viral titres. Administration of Met-RANTES, a CCR1 and CCR5 antagonist, led to impaired antiviral response with significantly higher viral titre in the liver on days 1 and 6 after infection. This observation was accompanied by a decreased and shortened recruitment of natural killer cells to the peritoneum of infected mice treated with the antagonist. Despite this reduced recruitment of antiviral leucocytes in mice receiving Met-RANTES, peritoneal cells from these mice produced markedly enhanced levels of pro-inflammatory cytokines. Altogether, the results suggest that CCR1 and/or CCR5 are important for both viral clearance and eventual control of the immune response.

Herpes Simplex Virus Type 2 as a Cause of Severe Meningitis in Immunocompromised Adults

We reviewed the clinical and demographic characteristics and outcomes for 13 immunocompromised patients with herpes simplex virus (HSV)-induced meningitis. Eleven patients were receiving chemotherapy for leukemia or lymphoma, and 10 had acquired immunodeficiency syndrome. Patients presented with acute febrile meningitis. The median white blood cell count at the onset of symptoms was 400 cells/mm3. Examination of cerebrospinal fluid (CSF) specimens showed lymphocytic meningitis, but activated lymphocytes and low glucose levels were both noted in 7 patients. HSV DNA was detected in all CSF specimens, and HSV type 2 was identified in 7. Eight patients had suspected HSV-associated mucocutaneous lesions at the time of meningitis onset. Six patients had initial radiculalgia, with sphincter involvement in 2. Eleven patients received intravenous antiviral therapy, but treatment was delayed for 6 patients. Two of the 6 patients for whom treatment was delayed developed encephalitis and died, whereas 2 others experienced persistent neurological symptoms. HSV-2 can cause severe meningitis in immunocompromised patients. Early recognition and treatment might improve the outcome of such infections.

Interleukin-15 and natural killer and NKT cells play a critical role in innate protection against genital herpes simplex virus type 2 infection

Interleukin-15 (IL-15), natural killer (NK) cells, and NK T (NKT) cells, components of the innate immune system, are known to contribute to defense against pathogens, including viruses. Here we report that IL-15(-/-) (NK(-) and NKT(-/+)) mice and RAG-2(-/-)/gamma(c)(-/-) (NK(-) and NKT(-)) mice that lack all lymphoid cells were very susceptible to vaginal infection with a low dose of herpes simplex virus type 2 (HSV-2). IL-15(-/-) and RAG-2(-/-)/gamma(c)(-/-) mice were 100-fold more susceptible and RAG-2(-/-), CD-1(-/-) (NKT(-)), and gamma interferon (IFN-gamma)(-/-) mice were 10-fold more susceptible to vaginal HSV-2 infection than control C57BL/6 mice. NK and/or NKT cells were the early source of IFN-gamma in vaginal secretions following genital HSV-2 infection. This study demonstrates that IL-15 and NK-NKT cells are critical for innate protection against genital HSV-2.

NP-1, a rabbit alpha-defensin, prevents the entry and intercellular spread of herpes simplex virus type 2

Rabbit neutrophil peptide-1 (NP-1), a prototypic alpha-defensin, protects cells in vitro from infection by clinical and laboratory isolates of herpes simplex virus type 2 (HSV-2). Incubation of concentrated virus stocks for 1 h with noncytotoxic concentrations of NP-1 reduces subsequent infection by >98%. Pretreating cells with NP-1 for 1 h prior to inoculation with untreated virus also prevents infection. NP-1, a cationic peptide, does not compete with viral envelope glycoproteins for binding to cellular heparan sulfate receptors, but it prevents viral entry. No VP16, a major viral tegument protein, is transported to the cell nucleus in the presence of NP-1. Infectious center assays demonstrate that NP-1 also inhibits cell-to-cell viral spread. Thus, NP-1 prevents virally mediated fusion events, entry, and cell-to-cell spread. This unique mechanism of anti-HSV activity, coupled with established antibacterial and possible anti-human immunodeficiency virus type 1 activities of defensins, render this family of compounds excellent candidates for further development as topical microbicides.

Use of immunostimulatory sequence-containing oligonucleotides as topical therapy for genital herpes simplex virus type 2 infection

Synthetic oligonucleotides containing CpG motifs in specific sequence contexts have been shown to induce potent immune responses. We have evaluated mucosal administration of two immunostimulatory sequence (ISS)-containing phosphorothioate-stabilized oligonucleotides for antiherpetic efficacy in animal models. The ISS oligonucleotides, suspended in phosphate-buffered saline, were tested in mouse and guinea pig vaginal models of herpes simplex virus type 2 (HSV-2) infection. For comparison, groups of untreated, non-ISS oligonucleotide-treated, and acyclovir-treated animals also were monitored. The results indicated that vaginal epithelial application of ISS (up to 6 h after viral inoculation) with mice lethally challenged with HSV-2 delayed disease onset and reduced the number of animals that developed signs of disease (P = 0.003). ISS application significantly increased survival rates over those of controls (P = 0.0014). The ISS also impacted an established infection in the guinea pig model of HSV-2 disease. A single administration of ISS (21 days after viral inoculation) significantly reduced the frequency and severity of HSV-2 lesions compared to results with non-ISS oligonucleotide-treated and untreated guinea pigs (P < 0.01). HSV-2 is shed from the vaginal cavity of the guinea pig in the absence of lesions, similar to the case with humans. As an additional indication of ISS efficacy, the magnitude of viral shedding also was significantly reduced in ISS-treated animals (P < 0.001). These effects appeared to be immunologically mediated, since ISS had no direct effect on HSV-2 replication in vitro using standard plaque assays. These data suggest that ISS may be useful in the treatment and control of genital herpes in humans.

Correlation of local interleukin-1beta levels with specific IgA response against Gardnerella vaginalis cytolysin in women with bacterial vaginosis

PROBLEM

Mucosal immune system activation may represent a critical determinant of adverse sequelae correlated with bacterial vaginosis, as HIV sexual transmission, upper genital tract infections, cervicitis, endometritis, postsurgical infections, and adverse pregnancy outcomes as preterm delivery (PTD), low birth weight (LBW).

METHOD OF STUDY

Levels of interleukin-1beta (IL-1beta), anti-Gardnerella vaginalis hemolysin (Gvh) IgA, pH, Nugent score, and number of leukocytes were measured in vaginal fluids of 60 fertile women with bacterial vaginosis and of 64 healthy controls.

RESULTS

Vaginal IL-1beta levels were nearly 13-fold higher in women with bacterial vaginosis (BV) and were associated with anti-Gvh IgA response. IL-1beta was positively correlated with leukocyte counts in the smear both in healthy and bacterial vaginosis positive women.

CONCLUSIONS

Induction of the proinflammatory cytokine IL-1beta may be a necessary event to elicit an innate immune response to control anaerobic genital tract infections. High levels of vaginal IL-1beta are associated with mounting of an antigen-specific mucosal immune response in women with bacterial vaginosis. Parallel induction of innate and adaptive immune response may be associated with protection from ascent of micro-organisms to the upper genital tract, and from acquiring viral infection through the vaginal tract.

New treatments for genital herpes

Genital herpes is a sexually transmitted disease that has been widely investigated from both an epidemiological and a diagnostic viewpoint. Better knowledge of the disease has pointed to the important role of asymptomatic herpes simplex virus type 2 shedding as a major culprit for the spread of the virus in the world, the latest statistics showing that the incidence of genital herpes is constantly increasing. The reference compound for the treatment and prophylaxis of genital herpes is acyclovir. Recently, two drugs with better oral bioavailability, valaciclovir, the oral prodrug of acyclovir, and famciclovir, the oral prodrug of penciclovir, have been made available. Nevertheless, there is a need to develop additional approaches, to extend the therapeutic possibilities and to face the problem of emerging resistant viruses, mostly in immunocompromised patients. Therefore, efforts have been made in different directions including the exploration of new targets for antiviral chemotherapy, the use of immunomodulators and the development of specific vaccines.