Innate immunity at the mucosal surface: role of toll-like receptor 3 and toll-like receptor 9 in cervical epithelial cell responses to microbial pathogens

Contribution of the seminal microbiome to paternal programming

The field of Developmental Origins of Health and Disease has primarily focused on maternal programming of offspring health. However, emerging evidence suggests that paternal factors, including the seminal microbiome, could potentially play important roles in shaping the developmental trajectory and long-term offspring health outcomes. Historically, the microbes present in the semen were regarded as inherently pathogenic agents. However, this dogma has recently been challenged by the discovery of a diverse commensal microbial community within the semen of healthy males. In addition, recent studies suggest that the transmission of semen-associated microbes into the female reproductive tract during mating has potentials to not only influence female fertility and embryo development but could also contribute to paternal programming in the offspring. In this review, we summarize the current knowledge on the seminal microbiota in both humans and animals followed by discussing their potential involvement in paternal programming of offspring health. We also propose and discuss potential mechanisms through which paternal influences are transmitted to offspring via the seminal microbiome. Overall, this review provides insights into the seminal microbiome-based paternal programing, which will expand our understanding of the potential paternal programming mechanisms which are currently focused primarily on the epigenetic modifications, oxidative stresses, and cytokines.

Co-infection of porcine deltacoronavirus and porcine epidemic diarrhea virus induces early TRAF6-mediated NF-κB and IRF7 signaling pathways through TLRs

Porcine deltacoronavirus (PDCoV) and porcine epidemic diarrhea virus (PEDV) infect the small intestine and cause swine enteric coronavirus disease. The mucosal innate immune system is the first line of defense against viral infection. The modulatory effect of PDCoV and PEDV coinfection on antiviral signaling cascades of the intestinal mucosa has not been reported. Here, we investigate the gene expression levels of pattern recognition receptors, downstream inflammatory signaling pathway molecules, and associated cytokines on the intestinal mucosa of neonatal piglets either infected with a single- or co-infected with PDCoV and PEDV using real-time PCR. The results demonstrate that single-PEDV regulates the noncanonical NF-κB signaling pathway through RIG-I regulation. In contrast, single-PDCoV and PDCoV/PEDV coinfection regulate proinflammatory and regulatory cytokines through TRAF6-mediated canonical NF-κB and IRF7 signaling pathways through TLRs. Although PDCoV/PEDV coinfection demonstrated an earlier modulatory effect in these signaling pathways, the regulation of proinflammatory and regulatory cytokines was observed simultaneously during single viral infection. These results suggested that PDCoV/PEDV coinfection may have synergistic effects that lead to enhanced viral evasion of the mucosal innate immune response.

Cell-Specific Expression Pattern of Toll-Like Receptors and Their Roles in Animal Reproduction

Toll-like receptors (TLRs), a part of the innate immune system, have critical roles in protection against infections and involve in basic pathology and physiology. Secreted molecules from the body or pathogens could be a ligand for induction of the TLR system. There are many immune and non-immune types of cells that express at a least single TLR on their surface or cytoplasm. Those cells may be a player in a defense system or in the physiological regulation mechanisms. Reproductive tract and organs contain different types of cells that have essential functions such as hormone production, providing an environment for embryo/fetus, germ cell production, etc. Although lower parts of reproductive organs are in a relationship with outsider contaminants (bacteria, viruses, etc.), upper parts should be sterile to provide a healthy pregnancy and germ cell production. In those areas, TLRs bear controller or regulator roles. In this chapter, we will provide current information about physiological functions of TLR in the cells of the reproductive organs and tract, and especially about their roles in follicle selection, maturation, follicular atresia, ovulation, corpus luteum (CL) formation and regression, establishment and maintenance of pregnancy, sperm production, maturation, capacitation as well as the relationship between TLR polymorphism and reproduction in domestic animals. We will also discuss pathogen-associated molecular patterns (PAMPs)-induced TLRs that involve in reproductive inflammation/pathology.

Can interruption of innate immune recognition-mediated emergency myelopoiesis impede tumor progression?

Cancer cells survive and grow despite various advanced anti-cancer therapy. To overcome this antineoplastic resistance, adjuvant therapy is often required to prevent cancer cells' immunoescape capacity. Established tumors build a stressful and hostile microenvironment in order to escape protective innate and adaptive immune responses. Specific conditions and factors within tumors, including hypoxia, nutrient starvation, acidic pH, and increased levels of free radicals, provoke a state of "endoplasmic reticulum stress" in both malignant cells and infiltrating myeloid cells. The stimulated endoplasmic reticulum stress can affect cancer progression via cross-talks with the innate immune system. Recently, the immunosuppressive activities of myeloid cells in the development of antineoplastic resistance are gaining more attention. Based on all these available data, we hypothesize that interruption of innate-immune recognition-mediated emergency myelopoiesis may be beneficial in halting cancer progression.

HIV susceptibility in women: The roles of genital inflammation, sexually transmitted infections and the genital microbiome

Given that heterosexual transmission of HIV across the genital mucosa is the most common route of infection in women, an in-depth understanding of the biological mechanisms associated with HIV risk in the female genital tract (FGT) is essential for effective control of the epidemic. Genital pro-inflammatory cytokines are well-described biological co-factors to HIV risk. Increased levels of pro-inflammatory cytokines in the FGT have been associated with a 3-fold higher-risk of acquiring HIV, presumably through involvement in barrier compromise and the recruitment of highly activated HIV target cells to the site of initial viral infection and replication. Sexually transmitted infections (STIs) and bacterial vaginosis (BV) are suggested possible contributors to genital inflammation in the FGT, and this, coupled with the relationship between genital inflammation and HIV risk, underscores the importance of effective treatment of STI and BV in the promotion of women's health. In most low- and middle-income countries, STIs are treated syndromically, a practice providing rapid treatment without identifying the infection source. However, this approach has been associated with over-diagnosis and the overuse of drugs. Further, because many women with STIs are asymptomatic, syndromic management also fails to treat a vast proportion of infected women. Although several studies have explored the role of STIs and the vaginal microbiome on genital inflammation and HIV risk, the impact of STI and BV management on genital inflammation remains poorly understood. This review aimed to collate the evidence on how BV and STI management efforts affect genital inflammation and the genital microbiome in women.

Immunology of HPV-mediated cervical cancer: current understanding

Human papilloma virus (HPV) has emerged as a primary cause of cervical cancer worldwide. HPV is a relatively small (55 nm in diameter) and non-enveloped virus containing approximately 8 kb long double stranded circular DNA genome. To date, 228 genotypes of HPV have been identified. Although all HPV infections do not lead to the development of malignancy of cervix, only persistent infection of high-risk types of HPV (mainly with HPV16 and HPV18) results in the disease. In addition, the immunity of the patients also acts as a key determinant in the carcinogenesis. Since, no HPV type specific medication is available for the patient suffering with cervical cancer, hence, a deep understanding of the disease etiology may be vital for developing an effective strategy for its prevention and management. From the immunological perspectives, the entire mechanisms of disease progression still remain unclear despite continuous efforts. In the present review, the recent developments in immunology of HPV-mediated cervix carcinoma were discussed. At the end, the prevention of disease using HPV type specific recombinant vaccines was also highlighted.

Insights into the Role of Innate Immunity in Cervicovaginal Papillomavirus Infection from Studies Using Gene-Deficient Mice

We demonstrate that female C57BL/6J mice are susceptible to a transient lower genital tract infection with MmuPV1 mouse papillomavirus and display focal histopathological abnormalities resembling those of human papillomavirus (HPV) infection. We took advantage of strains of genetically deficient mice to study in vivo the role of innate immune signaling in the control of papillomavirus. At 4 months, we sacrificed MmuPV1-infected mice and measured viral 757/3139 spliced transcripts by TaqMan reverse transcription-PCR (RT-PCR), localization of infection by RNAscope in situ hybridization, and histopathological abnormities by hematoxylin and eosin (H&E) staining. Among mice deficient in receptors for pathogen-associated molecular patterns, MyD88^-/- and STING^-/- mice had 1,350 and 80 copies of spliced transcripts/μg RNA, respectively, while no viral expression was detected in MAVS^-/- and Ripk2^-/- mice. Mice deficient in an adaptor molecule, STAT1^-/-, for interferon signaling had 46,000 copies/μg RNA. Among mice with targeted deficiencies in the inflammatory response, interleukin-1 receptor knockout (IL-1R^-/-) and caspase-1^-/- mice had 350 and 30 copies/μg RNA, respectively. Among mice deficient in chemokine receptors, CCR6^-/- mice had 120 copies/μg RNA, while CXCR2^-/- and CXCR3^-/- mice were negative. RNAscope confirmed focal infection in MyD88^-/-, STAT1^-/-, and CCR6^-/- mice but was negative for other gene-deficient mice. Histological abnormalities were seen only in the latter mice. Our findings and the literature support a working model of innate immunity to papillomaviruses involving the activation of a MyD88-dependent pathway and IL-1 receptor signaling, control of viral replication by interferon-stimulated genes, and clearance of virus-transformed dysplastic cells by the action of the CCR6/CCL20 axis.IMPORTANCE Papillomaviruses infect stratified squamous epithelia, and the viral life cycle is linked to epithelial differentiation. Additionally, changes occur in viral and host gene expression, and immune cells are activated to modulate the infectious process. In vitro studies with keratinocytes cannot fully model the complex viral and host responses and do not reflect the contribution of local and migrating immune cells. We show that female C57BL/6J mice are susceptible to a transient papillomavirus cervicovaginal infection, and mice deficient in select genes involved in innate immune responses are susceptible to persistent infection with variable manifestations of histopathological abnormalities. The results of our studies support a working model of innate immunity to papillomaviruses, and the model provides a framework for more in-depth studies. A better understanding of mechanisms of early viral clearance and the development of approaches to induce clearance will be important for cancer prevention and the treatment of HPV-related diseases.

Subversion of Host Innate Immunity by Human Papillomavirus Oncoproteins

The growth of human papillomavirus (HPV)-transformed cells depends on the ability of the viral oncoproteins E6 and E7, especially those from high-risk HPV16/18, to manipulate the signaling pathways involved in cell proliferation, cell death, and innate immunity. Emerging evidence indicates that E6/E7 inhibition reactivates the host innate immune response, reversing what until then was an unresponsive cellular state suitable for viral persistence and tumorigenesis. Given that the disruption of distinct mechanisms of immune evasion is an attractive strategy for cancer therapy, the race is on to gain a better understanding of E6/E7-induced immune escape and cancer progression. Here, we review recent literature on the interplay between E6/E7 and the innate immune signaling pathways cGAS/STING/TBK1, RIG-I/MAVS/TBK1, and Toll-like receptors (TLRs). The overall emerging picture is that E6 and E7 have evolved broad-spectrum mechanisms allowing for the simultaneous depletion of multiple rather than single innate immunity effectors. The cGAS/STING/TBK1 pathway appears to be the most heavily impacted, whereas the RIG-I/MAVS/TBK1, still partially functional in HPV-transformed cells, can be activated by the powerful RIG-I agonist M8, triggering the massive production of type I and III interferons (IFNs), which potentiates chemotherapy-mediated cell killing. Overall, the identification of novel therapeutic targets to restore the innate immune response in HPV-transformed cells could transform the way HPV-associated cancers are treated.

Radiation induces changes in toll-like receptors of the uterine cervix of the rat

Radiotherapy is an important therapeutic approach against cervical cancer but associated with adverse effects including vaginal fibrosis and dyspareunia. We here assessed the immunological and oxidative responses to cervical irradiation in an animal model for radiation-induced cervicitis. Rats were sedated and either exposed to 20 Gy of ionising radiation given by a linear accelerator or only sedated (controls) and euthanized 1–14 days later. The expressions of toll-like receptors (TLRs) and coupled intracellular pathways in the cervix were assessed with immunohistofluorescence and western blot. Expression of cytokines were analysed with the Bio-Plex Suspension Array System (Bio-Rad). We showed that TLRs 2–9 were expressed in the rat cervix and cervical irradiation induced up-regulation of TLR5, TRIF and NF-κB. In the irradiated cervical epithelium, TLR5 and TRIF were increased in concert with an up-regulation of oxidative stress (8-OHdG) and antioxidant enzymes (SOD-1 and catalase). G-CSF, M-CSF, IL-10, IL- 17A, IL-18 and RANTES expressions in the cervix decreased two weeks after cervical irradiation. In conclusion, the rat uterine cervix expresses the TLRs 2–9. Cervical irradiation induces immunological changes and oxidative stress, which could have importance in the development of adverse effects to radiotherapy.

Mucosal Vaccine Approaches for Prevention of HIV and SIV Transmission

Optimal protective immunity to HIV will likely require that plasma cells, memory B cells and memory T cells be stationed in mucosal tissues at portals of viral entry. Mucosal vaccine administration is more effective than parenteral vaccine delivery for this purpose. The challenge has been to achieve efficient vaccine uptake at mucosal surfaces, and to identify safe and effective adjuvants, especially for mucosally administered HIV envelope protein immunogens. Here, we discuss strategies used to deliver potential HIV vaccine candidates in the intestine, respiratory tract, and male and female genital tract of humans and nonhuman primates. We also review mucosal adjuvants, including Toll-like receptor agonists, which may adjuvant both mucosal humoral and cellular immune responses to HIV protein immunogens.

Association of cervical microbial community with persistence, clearance and negativity of Human Papillomavirus in Korean women: a longitudinal study

The present study aimed to identify the cervical microbes that are associated with HPV negativity, HPV clearance and HPV persistence and to assess the microbes’ longitudinal associations as related to HPV infection dynamics among Korean women. We enrolled 41 women with 107 samples, and classified them according to the HPV infection dynamics: HPV negativity (21 samples, 10 subjects), HPV clearance (42 samples, 15 subjects), and HPV persistence (44 samples, 16 subjects). Cervical swabs were collected at the baseline and six-month-interval follow-up visits. HPV positivity was determined by HPV DNA HC2 assay, and the microbiome was analyzed using 16SrRNA pyrosequencing, linear discriminant analysis effect size and multivariate logistic analysis. In the multivariate logistic analysis results, Lactobacillus crispatus (multivariate OR (mOR) = 8.25, 95% CI 2.13~32.0) was predominant in the HPV-negative group. We observed that Eubacterium eligens (mOR = 11.5, 95% CI 1.31~101.4), Gardnerella vaginalis (mOR = 17.0, 95% CI 2.18–131.8), and Ureaplasma urealyticum (mOR = 7.42, 95% CI 1.3–42.46) had the strongest associations with HPV clearance, and Lactobacillus johnsonii (mOR = 16.4, 95% CI 1.77–152.2) with HPV persistence. Overall, greater diversity was observed in HPV-persistence than in HPV-negative women. Our findings suggest that the presence and prevalence of a specific cervical microbiome are factors involved in HPV dynamics.

Recognizing conserved non-canonical localization patterns of toll-like receptors in tissues and across species

Toll-like receptors (TLR) 1, 2, 4, 5 and 6 were originally characterized as exclusively expressed on the cell surface and TLR 3, 7, 8 and 9 were said to be localized to the endosomes. However, continued research in this area shows that TLR localization may be altered across cell-types, and in response to stimulation, age or disease. Mucosal surfaces must remain tolerant to the commensal flora and thus intracellular or basal lateral localization of TLRs at mucosal surfaces may be necessary to prevent induction of an inflammatory response to commensal flora while still allowing the possibility for the receptors to prime an immune response when a pathogen has crossed the epithelial barrier. Here, we highlight the research specifying 'non-canonical' localization of TLRs in human and animal mucosal tissues and blood-derived cells, while excluding cultured polarized immortalized cells. Reports that only indicate TLR gene/protein expression and/or responsiveness to agonists have been excluded unless the report also indicates surface/intracellular distribution in the cell. Understanding the tissue- and species-specific localization of these specific pattern recognition receptors will lead to a greater appreciation of the way in which TLR ligands promote innate immunity and influence the adaptive immune response. A more comprehensive understanding of this information will potentially aid in the exploitation of the therapeutic or adjuvant potential of selectively localized TLRs and in opening new perspectives in understanding the basis of immunity.

Sessile Innate Immune Cells

In this chapter, sessile cells of the innate immune system are briefly introduced. Defined as cells equipped with diverse pattern recognition molecules capable of detecting MAMPs and DAMPs, they encompass cells such as epithelial cells, fibroblasts, vascular cells, chondrocytes, osteoblasts, and adipocytes. Located at the body surfaces, epithelial cells represent the first line of innate immune defense against invading microbial pathogens. They are significant contributors to innate mucosal immunity and generate various antimicrobial defense mechanisms. Also, epithelial cells critically contribute to tissue repair via the phenomenon of re-epithelialization. Fibroblasts operate as classical sentinel cells of the innate immune system dedicated to responding to MAMPs and DAMPs emitted upon any tissue injury. Typically, fibroblasts synthesize most of the extracellular matrix of connective tissues, thereby playing a crucial role in tissue repair processes. Vascular cells of the innate immune system represent an evolutionarily developed first-line defense against any inciting insult hitting the vessel walls from the luminal side including bacteria, viruses, microbial toxins, and chemical noxa such as nicotine. Upon such insults and following recognition of MAMPs and DAMPs, vascular cells react with an innate immune response to create an acute inflammatory milieu in the vessel wall aimed at curing the vascular injury concerned. Chondrocytes, osteoblasts, and osteoclasts represent other vital cells of the skeletal system acting as cells of the innate immune system in its wider sense. These cells mediate injury-promoted DAMP-induced inflammatory and regenerative processes specific for the skeletal systems. Finally, adipocytes are regarded as highly active cells of the innate immune system. As white, brown, and beige adipocytes, they operate as a dynamic metabolic organ that can secrete certain bioactive molecules which have endocrine, paracrine, and autocrine actions.

Toll-like receptor (TLR)21 signalling-mediated antiviral response against avian influenza virus infection correlates with macrophage recruitment and nitric oxide production

Cytosine-guanosinedeoxynucleotide (CpG) DNA can be used for the stimulation of the toll-like receptor (TLR)21 signalling pathway in avian species which ultimately leads to up-regulation of gene transcription for pro-inflammatory molecules including nitric oxide and recruitment of innate immune cells. The objective of this study was to determine the antiviral effect of NO, produced in response to in ovo delivery of CpG DNA, against avian influenza virus (AIV) infection. We found that when CpG DNA is delivered at embryo day (ED)18 in ovo and subsequently challenged with H4N6 AIV at ED19 pre-hatch and day 1 post-hatching, CpG DNA reduces H4N6 AIV replication associated with enhanced NO production and macrophage recruitment in lungs. In vitro, we showed that NO originating from macrophages is capable of eliciting an antiviral response against H4N6 AIV infection. This study provides insights into the mechanisms of CpG DNA-mediated antiviral response, particularly against AIV infection in avian species.

Expression of Toll-like receptor 9 increases with progression of cervical neoplasia in Tunisian women--a comparative analysis of condyloma, cervical intraepithelial neoplasia and invasive carcinoma

Toll-like receptors (TLRs) are expressed in immune and tumor cells and recognize pathogen-associated molecular patterns. Cervical cancer (CC) is directly linked to a persistent infection with high risk human papillomaviruses (HR-HPVs) and could be associated with alteration of TLRs expression. TLR9 plays a key role in the recognition of DNA viruses and better understanding of this signaling pathway in CC could lead to the development of novel immunotherapeutic approaches. The present study was undertaken to determine the level of TLR9 expression in cervical neoplasias from Tunisian women with 53 formalin-fixed and paraffin-embedded specimens, including 22 samples of invasive cervical carcinoma (ICC), 18 of cervical intraepithelial neoplasia (CIN), 7 of condyloma and 6 normal cervical tissues as control cases. Quantification of TLR9 expression was based on scoring four degrees of extent and intensity of immunostaining in squamous epithelial cells. TLR9 expression gradually increased from CIN1 (80% weak intensity) to CIN2 (83.3% moderate), CIN3 (57.1% strong) and ICC (100% very strong). It was absent in normal cervical tissue and weak in 71.4% of condyloma. The mean scores of TLR9 expression were compared using the Kruskall-Wallis test and there was a statistical significance between normal tissue and condyloma as well as between condyloma, CINs and ICC. These results suggest that TLR9 may play a role in progression of cervical neoplasia in Tunisian patients and could represent a useful biomarker for malignant transformation of cervical squamous cells.

Cytokine activation during embryonic development and in hen ovary and vagina during reproductive age and Salmonella infection

Salmonellosis is one of the most important zoonotic diseases and is usually associated with consumption of Salmonella Enteritidis (SE) contaminated poultry meat or eggs. Contamination with SE is usually the result of infection of the digestive tract, or reproductive organs, especially the ovary and vagina. Thus, knowledge of endogenous innate immune mechanisms operating in the ovary and vagina of hen is an emerging aspect of reproductive physiology. Cytokines are key factors for triggering the immune response and inflammation in chicken to Salmonella infection. The aim of this study was to investigate the expression profile of 11 proinflammatory cytokines in the chicken embryos during embryonic development, as well as in the hen ovary and vagina in vivo, to investigate whether sexual maturation affects their ovarian and vaginal mRNA abundance and to determine whether cytokine expression was constitutive or induced in the ovary and vagina as a response to SE infection. RT-PCR analysis revealed that several cytokines were expressed in the chicken embryos, and in the ovary and vagina of healthy birds. Expression of various cytokines during sexual maturation appeared to be developmentally regulated. In addition, a significant up-regulation of several cytokines in the ovary and vagina of sexually mature SE infected birds compared to healthy birds of the same age was observed. These results suggest a cytokine-mediated immune response mechanism against Salmonella infection in the hen reproductive organs.

Transcriptional changes of cytokines in rooster testis and epididymis during sexual maturation stages and Salmonella infection

Infection of rooster testis and epididymis by pathogens can lead to impaired fertility, resulting in economic losses in the poultry industry. Antimicrobial protection of rooster reproductive organs is, therefore, an important aspect of reproductive physiology. Salmonellosis is one of the most important zoonotic diseases, caused by Salmonella bacteria including Salmonella Enteritidis (SE) and is usually the result of infection of the reproductive organs. Thus, knowledge of the endogenous innate immune mechanisms of the rooster testis and epididymis is an emerging aspect of reproductive physiology. Cytokines are key factors for stimulating the immune response and inflammation in chickens to Salmonella infection. In the present study the expression profile of 11 pro-inflammatory cytokine genes in the rooster testis and epididymis in vivo and transcriptional changes in these organs during sexual maturation and SE infection were investigated. Gene expression analysis data revealed that in both testis and epididymis nine cytokines namely the IL-1β, IL-6, IL-8, IL-10, IL-12, IL-15, IL-16, IL-17 and IL-18 genes were expressed, while no mRNA transcripts were detected in both organs for IL-2 and IL-4. Furthermore, the expression of various cytokine genes during sexual maturation appeared to be developmentally regulated, while SE infection resulted in a significant up-regulation of IL-1β, -6, -12 and -18 genes in the testis and an increase in the mRNA relative abundance of IL-1β, -6, -12, -16 and -18 in the epididymis of SE-infected sexually mature 28-week-old roosters. These results suggest a cytokine-mediated immune response mechanism against Salmonella infection in the rooster reproductive tract.

The Effect of Estradiol and Progesterone on Toll Like Receptor Gene Expression in A Human Fallopian Tube Epithelial Cell Line

Objective

Toll like receptors (TLRs) are one of the main components of the innate im- mune system. It has been reported that expression of these receptors are altered in the female reproductive tract (FRT) during menstrual cycle. Here we used a fallopian tube epithelial cell line (OE-E6/E7) to evaluate the effect of two sex hormones in modulating TLR expression.

Materials and Methods

In this experimental study, initially TLR gene expression in OE- E6/E7 cells was evaluated and compared with that of fallopian tube tissue using quanti- tative real time-polymerase chain reaction (qRT-PCR) and immunostaining. Thereafter, OE-E6/E7 cells were cultured with different concentrations of estradiol and progesterone, and combination of both. qRT-PCR was performed to reveal any changes in expression of TLR genes as a result of hormonal treatment.

Results

TLR1-10 genes were expressed in human fallopian tube tissue. TLR1-6 genes and their respective proteins were expressed in the OE-E6/E7 cell line. Although estradiol and progesterone separately had no significant effect on TLR expression, their combined treatment altered the expression of TLRs in this cell line. Also, the pattern of TLR expres- sion in preovulation (P), mensturation (M) and window of implantation (W) were the same for all TLRs with no significant differences between P, M and W groups.

Conclusion

These data show the significant involvement of the combination of es- tradiol and progesterone in modulation of TLR gene expression in this human fal- lopian tube cell line. Further experiments may reveal the regulatory mechanism and signalling pathway behind the effect of sex hormones in modulating TLRs in the hu- man FRT.

Human papillomavirus-exposed Langerhans cells are activated by stabilized Poly-I:C

Human papillomaviruses (HPV) establish persistent infections because of evolved immune evasion mechanisms, particularly HPV-mediated suppression of the immune functions of Langerhans cells (LC), the antigen presenting cells of the epithelium. Polyinosinic-polycytidilic acid (Poly-I:C) is broadly immunostimulatory with the ability to enhance APC expression of costimulatory molecules and inflammatory cytokines resulting in T cell activation. Here we investigated the activation of primary human LC derived from peripheral blood monocytes after exposure to HPV16 virus like particles followed by treatment with stabilized Poly-I:C compounds (s-Poly-I:C), and their subsequent induction of HPV16-specific T cells. Our results indicate that HPV16 particles alone were incapable of inducing LC activation as demonstrated by the lack of costimulatory molecules, inflammatory cytokines, chemokine-directed migration, and HPV16-specific CD8⁺ T cells in vitro. Conversely, s-Poly-I:C caused significant upregulation of costimulatory molecules and induction of chemokine-directed migration of LC that were pre-exposed to HPV16. In HLA-A*0201-positive donors, s-Poly-I:C treatment was able to induce CD8⁺ T cell immune responses against HPV16-derived peptides. Thus, s-Poly-I:C compounds are attractive for translation into therapeutics in which they could potentially mediate clearance of persistent HPV infection.

Langerhans cells from women with cervical precancerous lesions become functionally responsive against human papillomavirus after activation with stabilized Poly-I:C

Human papillomavirus (HPV)-mediated suppression of Langerhans cell (LC) function can lead to persistent infection and development of cervical intraepithelial neoplasia (CIN). Women with HPV-induced high-grade CIN2/3 have not mounted an effective immune response against HPV, yet it is unknown if LC-mediated T cell activation from such women is functionally impaired against HPV. We investigated the functional activation of in vitro generated LC and their ability to induce HPV16-specific T cells from CIN2/3 patients after exposure to HPV16 followed by treatment with stabilized Poly-I:C (s-Poly-I:C). LC from patients exposed to HPV16 demonstrated a lack of costimulatory molecule expression, inflammatory cytokine secretion, and chemokine-directed migration. Conversely, s-Poly-I:C caused significant phenotypic and functional activation of HPV16-exposed LC, which resulted in de novo generation of HPV16-specific CD8(+) T cells. Our results highlight that LC of women with a history of persistent HPV infection can present HPV antigens and are capable of inducing an adaptive T cell immune response when given the proper stimulus, suggesting that s-Poly-I:C compounds may be attractive immunomodulators for LC-mediated clearance of persistent HPV infection.

CpG DNA analysis of bacterial STDs

BACKGROUND

Bacterial infections in the genital tract frequently result in morbidity through a variety of inflammation based symptoms. One component of the bacteria that may trigger host inflammatory response is their DNA. CpG motifs in this DNA are known targets for Toll-like receptor 9 (TLR9), which is a pathogen-recognition receptors focusing on CpG DNA. The activation of TLR9 induces the NF-κB inflammatory pathway. This study aims to provide a broad view of the inflammatory potential of CpG DNA motifs in bacteria related to genital diseases: C. trachomatis, E. coli, N. gonorrhoeae, G. vaginalis, H. ducreyi, L. crispatus, L. gasseri, M. hominis, M. genitalium, T. pallidum, and U. urealyticum.

METHODS

Publicly available genomic sequences of the bacterial species and strains have been analyzed in silico to produce a CpG index number. This CpG index number shows the relative inflammatory potential of the genome and has previously been used in a study by Lundberg et al. (2003). Higher CpG index values suggest a strong CpG induced inflammation potential during infection and vice versa.

RESULTS

The highest observed CpG index belongs to G. vaginalis with a value of 26,2, suggesting a strong pro-inflammatory potential when in contact with TLR9. The lowest index belongs to N. gonorrhoeae with a value of -79,5, suggesting a strong immunoinhibitory effect on TLR9 contact. Interestingly, Lactobacilli showed a mean CpG index value of 4,2, suggesting a weak inflammatory potential.

DISCUSSION

Our results show varying CpG index values between bacterial species. Comparison of CpG indices with the clinical course of several pathogens shows the CpG index helps clarify the clinical course of infection. However, we found no links between CpG index values and either obligate pathogenicity or facultative pathogenicity through bacterial vaginosis. Lactobacilli showed relatively low CpG indices which do suggest a lower inflammatory potential from these bacteria.

CONCLUSIONS

Our results show varying CpG index values between bacterial species, which may help clarify the clinical course of infection, and may help diagnosis.

Early Defensive Mechanisms against Human Papillomavirus Infection

Cervical cancer is the fourth most common cancer in women and is almost exclusively caused by human papillomavirus (HPV) infection. HPV is also frequently associated with other cancers arising from mucosal epithelium, including anal and oropharyngeal cancers, which are becoming more common in both men and women. Viral persistence and progression through precancerous lesion stages are prerequisites for HPV-associated cancer and reflect the inability of cell-mediated immune mechanisms to clear infections and eliminate abnormal cells in some individuals. Cell-mediated immune responses are initiated by innate pathogen sensing and subsequent secretion of soluble immune mediators and amplified by the recruitment and activation of effector T lymphocytes. This review discusses early defensive mechanisms of innate responders to natural HPV infection, their influence on response polarization, and the underappreciated role of keratinocytes in this process.

High-risk human papillomavirus targets crossroads in immune signaling

Persistent infections with a high-risk type human papillomavirus (hrHPV) can progress to cancer. High-risk HPVs infect keratinocytes (KCs) and successfully suppress host immunity for up to two years despite the fact that KCs are well equipped to detect and initiate immune responses to invading pathogens. Viral persistence is achieved by active interference with KCs innate and adaptive immune mechanisms. To this end hrHPV utilizes proteins encoded by its viral genome, as well as exploits cellular proteins to interfere with signaling of innate and adaptive immune pathways. This results in impairment of interferon and pro-inflammatory cytokine production and subsequent immune cell attraction, as well as resistance to incoming signals from the immune system. Furthermore, hrHPV avoids the killing of infected cells by interfering with antigen presentation to antigen-specific cytotoxic T lymphocytes. Thus, hrHPV has evolved multiple mechanisms to avoid detection and clearance by both the innate and adaptive immune system, the molecular mechanisms of which will be dealt with in detail in this review.

Host detection and the stealthy phenotype in influenza virus infection

The innate host response to influenza virus infection plays a critical role in determining the subsequent course of infection and the clinical outcome of disease. The host has a diverse array of detection and effector mechanisms that are able to recognize and initiate effective antiviral responses. In opposition, the virus utilizes a number of distinct mechanisms to evade host detection and effector activity in order to remain "stealthy" throughout its replication cycle. In this review, we describe these host and viral mechanisms, including the major pattern recognition receptor families (the TLRs, NLRs, and RLRs) in the host and the specific viral proteins such as NS1 that are key players in this interaction. Additionally, we explore nonreductive mechanisms of viral immune evasion and propose areas important for future inquiry.

TLR9 is expressed in human papillomavirus-positive cervical cells and is overexpressed in persistent infections

Control of human papillomavirus (HPV) infection involves the activation of Toll-like receptors (TLRs), key components of the mucosal antiviral response. Available studies on TLR expression in HPV-positive cervical cells are limited and reported conflicting results. This study quantified TLR 2, 3, 4, 7 and 9 transcripts in low-risk (LR) and high-risk (HR) HPV-positive and HPV-negative cervical samples from 154 women attending a gynaecological clinic. Expression levels of TLR 2, 3, 4 and 7 did not differ among samples, whereas TLR9 levels were quite significantly higher in LR and marginally significant in HR HPV-positive samples, with respect to the HPV-negative samples. Interestingly, in a subgroup of women with documented previous HPV-infection, TLR9 levels were extremely higher in patients persistently positive to the same HPV genotype for more than 1 year, with respect to women who cleared HPV infection and to those re-infected with a different genotype. These findings implicate TLR9 in the response to LR and HR HPVs, including HPV 16 known to interfere with TLR9 transcription in cell lines. Elevated TLR9 levels without HPV clearance in persistently infected women could drive inflammation thereby contributing to cervical cancer risk.

Human platelets express Toll-like receptor 3 and respond to poly I:C

Platelets functions in hemostasis have been widely studied. Currently, growing evidence shows that platelets have also a role in the immune innate response. Recently, protein expression of Toll-like receptors (TLR's) 2, 4, 7, 8, and 9, and the presence of TLRs 1 and 6 mRNA in human platelets was described. Up to now the functionality of TLR-2, 4 and 9 in human platelets has been demonstrated. Due to the relevance of TLRs functions to PAMPS (pathogen-associated molecular patterns) recognizing, we evaluated the presence of TLR3 in human platelets founding low percentages of platelets expressing surface or intracellular TLR3 protein. The activation with thrombin induced an increase in the percentage of platelets expressing surface TLR3 and higher levels of TLR3 expression in the whole population. Human platelets responded to poly I:C by increasing [Ca(2+)]i, the percentages of cells expressing TLR4 and CD62P, and by releasing CXCL4 and IL-1β in comparison to unstimulated platelets. These results demonstrate that human platelets express TLR3 and are capable of responding to poly I:C, suggesting that these cells might influence the immune innate response when detecting viral dsRNA.

Expression and functional analysis of Toll-like receptor 4 in human cervical carcinoma

Toll-like receptors are expressed in human immune cells and many tumors, but the role of toll-like receptor 4 (TLR4) in the development of tumors is controversial. We demonstrated the expression, distribution, and functional activity of TLR4 in tissues of normal cervix, cervical intraepithelial neoplasia (CIN), invasion cervical cancers (ICC), and different human papillomavirus (HPV)-infected cervical cancer cells. The results showed that TLR4 expression was in accordance with the histopathological grade: higher in ICC than in CIN, and low in normal cervical tissues and malignant cervical stroma. Expression was higher in SiHa (HPV16+) than in HeLa (HPV18+) cells, but was not observed in C33A (HPV-) cells. After treatment with its agonist, lipopolysaccharide (LPS), the expression levels of TLR4 was increased and apoptosis resistance was induced in SiHa cells, but not in HeLa or C33A cells. Meanwhile, LPS treatment did not alter the cell cycle distribution in SiHa cells. The mechanism of apoptosis resistance may be related to HPV16 infection and not correlated with the cell cycle distribution. Targeting TLR4 in combination with traditional drug treatment may serve as a novel strategy for more effectively killing cancer cells.

Role of the innate immunity in female reproductive tract

The mucosal immune system in the female reproductive tract (FRT) is well equipped to meet the sexually transmitted pathogens, allogeneic sperm, and the immunologically distinct fetus. Analysis of the FRT indicates that epithelial cells provide a physical barrier against pathogens and microbial infections as well as secretions containing anti-microbial peptides, cytokines, and chemokines which recruit and activate immune cells. Epithelial and immune cells confer protection in part through Toll-like receptors. The aim of this literature is to review the diverse components of the innate immune system, contributing to an exclusive protection system throughout the FRT.

TLR9 and RIG-I signaling in human endocervical epithelial cells modulates inflammatory responses of macrophages and dendritic cells in vitro

The innate immune system has evolved to recognize invading pathogens through pattern recognition receptors (PRRs).Among PRRs, Toll like receptors (TLRs 3, 7/8,9) and RIG-I like receptors (RLRs) have been shown to recognize viral components. Mucosal immune responses to viral infections require coordinated actions from epithelial as well as immune cells. In this respect, endocervical epithelial cells (EEC's) play an important role in initiating innate immune responses via PRRs. It is unknown whether EEC's can alter immune responses of macrophages and dendritic cells (DC's) like its counterparts in intestinal and respiratory systems. In this study, we show that endocervical epithelial cells (End1/E6E7) express two key receptors, TLR9 and RIG-I involved in anti-viral immunity. Stimulation of End1/E6E7 cells lead to the activation of NF-κB and increased secretion of pro-inflammatory cytokines, IL-6 and IL-8. Polarized End1/E6E7 cells responded to apical stimulation with ligands of TLR9 and RIG-I, CpG-ODN and Poly(I:C)LL respectively, without compromising End1/E6E7 cell integrity. At steady state, spent medium from End1/E6E7 cells significantly reduced secretion of pro-inflammatory cytokines from LPS treated human primary monocyte derived macrophages (MDMs) and DC:T cell co-cultures. Spent medium from End1/E6E7 cells stimulated with ligands of TLR9/RIG-I restored secretion of pro-inflammatory cytokines as well as enhanced phagocytosis and chemotaxis of monocytic U937 cells. Spent medium from CpG-ODN and Poly(I:C)LL stimulated End1/E6E7 cells showed significant increased secretion of IL-12p70 from DC:T cell co-cultures. The anti-inflammatory effect of spent media of End1/E6E7 cell was observed to be TGF-β dependent. In summary, the results of our study indicate that EEC's play an indispensable role in modulating anti-viral immune responses at the female lower genital tract.

TLR4-MyD88/Mal-NF-kB axis is involved in infection of HSV-2 in human cervical epithelial cells

We have established an in vitro HSV-2 acute infection model with Human cervical epithelial (HCE cells, the primary target and natural host cells for HSV-2) to investigate the role of TLRs-mediated innate immune response to HSV-2. In current study, we found that HSV-2 infection induced activity of NF-kB reporter and expression of cytokines are TLR4-dependent using approaches with shRNA and TLR4 antagonist. Knockdown experiments demonstrated that the adaptor molecules MyD88 and Mal of the TLRs signaling pathway are required in the HSV-2 induced TLR4-dependent NF-kB activation in HCE cells. Western blot assay suggested that knockdown of TLR4 decreased the phosphorylation of IRAK1 and inhibitor of NF-kB (IkB-α) upon HSV-2 infection. Finally, decreased expression of either TLR4 or MyD88/Mal alone or both significantly abolished productions of IL-6 and IFN-β by ELISA analysis. Taken together, our results from the in vitro infection model reveal for the first time that there exists the pathway via TLR4-Mal/MyD88-IRAK1-NF-kB axis in human cervical epithelial cells in response to HSV-2 infection.

Ovarian steroid hormones: effects on immune responses and Chlamydia trachomatis infections of the female genital tract

Female sex hormones are known to regulate the adaptive and innate immune functions of the female reproductive tract. This review aims to update our current knowledge of the effects of the sex hormones estradiol and progesterone in the female reproductive tract on innate immunity, antigen presentation, specific immune responses, antibody secretion, genital tract infections caused by Chlamydia trachomatis, and vaccine-induced immunity.

Chlamydia trachomatis infection of the male genital tract: an update

Chlamydia trachomatis (CT) is the most prevalent cause of sexually transmitted diseases. Although the prevalence of chlamydial infection is similar in men and women, current research and screening are still focused on women, who develop the most severe complications, leaving the study of male genital tract (MGT) infection underrated. Herein, we reviewed the literature on genital CT infection with special focus on the MGT. Data indicate that CT certainly infects different parts of the MGT such as the urethra, seminal vesicles, prostate, epididymis and testis. However, whether or not CT infection has detrimental effects on male fertility is still controversial. The most important features of CT infection are its chronic nature and the presence of a mild inflammation that remains subclinical in most individuals. Chlamydia antigens and pathogen recognition receptors (PRR), expressed on epithelial cells and immune cells from the MGT, have been studied in the last years. Toll-like receptor (TLR) expression has been observed in the testis, epididymis, prostate and vas deferens. It has been demonstrated that recognition of chlamydial antigens is associated with TLR2, TLR4, and possibly, other PRRs. CT recognition by PRRs induces a local production of cytokines/chemokines, which, in turn, provoke chronic inflammation that might evolve in the onset of an autoimmune process in genetically susceptible individuals. Understanding local immune response along the MGT, as well as the crosstalk between resident leukocytes, epithelial, and stromal cells, would be crucial in inducing a protective immunity, thus adding to the design of new therapeutic approaches to a Chlamydia vaccine.

Induction of avian β-defensins by CpG oligodeoxynucleotides and proinflammatory cytokines in hen vaginal cells in vitro

Immune function in the vagina of hen oviduct is essential to prevent infection by microorganisms colonizing in the cloaca. The aim of this study was to determine whether CpG oligodeoxynucleotides (CpG-ODN) stimulate the expression of avian β-defensins (AvBDs) in hen vaginal cells. Specific questions were whether CpG-ODN affects the expression of AvBDs and proinflammatory cytokines and whether the cytokines affect AvBDs expression in vaginal cells. The dispersed vaginal cells of White Leghorn laying hens were cultured and stimulated by different doses of lipopolysaccharide (LPS), CpG-ODN, interleukin 1β (IL1B), or IL6. The cultured cell population contained epithelial cells, fibroblast-like cells, and CD45-positive leukocytes. The immunoreactive AvBD3, -10, and -12 were localized in the mucosal epithelium in the section of the vagina. The expression of AvBDs, IL1B, and IL6 was analyzed by quantitative RT-PCR. RT-PCR analysis showed the expression of AvBD1, -3, -4, -5, -10, and -12 in the cultured vaginal cells without stimulation. Toll-like receptors (TLRs) 4 and 21, which recognize LPS and CpG-ODN respectively and IL1 and IL6 receptors (IL1R1 and IL6R) were also expressed in them. The expression of IL1B, IL6, and AvBD10 and -12 was upregulated by LPS, whereas only IL1B and IL6 were upregulated by CpG-ODN. IL1B stimulation upregulated AvBD1 and -3 expression, whereas IL6 stimulation did not cause changes in AvBDs expression. These results suggest that CpG-ODN derived from microbes upregulates the expression of IL1B and IL6 by interaction with TLR21 and then IL1B induces AvBD1 and -3 to prevent infection in the vagina.

Cervical cytokines and clearance of incident human papillomavirus infection: Hawaii HPV cohort study

Mechanisms for the control and resolution of human papillomavirus (HPV) infection of the cervix include the local production of cytokines, which control recruitment and function of cells integral to pathogen control. We established a cohort of women for long-term follow-up to examine the mucosal expression of antiviral (IFN-α2), Type-1 (IFN-γ, IL-12), regulatory (IL-10), and proinflammatory (IL-1α, IL-1β, IL-6, IL-8, MIP-1α, and TNF) cytokines in association with the clearance of incident cervical HPV infection. Interviews and specimens for HPV DNA analysis and cytokine protein measurement were obtained at baseline and at 4-month intervals. A Cox proportional hazards model was used to study the relationship between clearance of 107 high-risk and 111 low-risk incident HPV infections and cytokine levels among 154 women. Positive changes from baseline levels of IL-10, IL-12, MIP-1α, and TNF were associated with significantly longer times to type-specific HPV clearance. Inverse trends in the hazard ratios associated with clearance of high-risk HPV infections were monotonic and significant for IL-12 (ptrend  = 0.02) and TNF (ptrend  = 0.02); the likelihood of high-risk HPV clearance was reduced by 65% and 67%, respectively, among women in the highest as compared with the lowest quartile of change from baseline. Our results suggest that in women with a nontransient cervical HPV infection, proinflammatory, Type-1, and regulatory cytokines are elevated, underscoring the long-term commitment of local immune mediators to viral eradication.

Toll-like receptors in human papillomavirus infection

Infection with human papillomaviruses (HPVs) often causes cutaneous benign lesions, cervical cancer, and a number of other tumors. The mechanisms of host immune system to prevent and control HPV infection still remain poorly understood. Toll-like receptors (TLRs) are specific pattern recognition molecules that bind to microbial components to trigger innate immunity and direct adaptive immunity in the face of immunological danger. TLRs have been established to play an essential role in sensing and initiating antiviral immune responses. Recent accumulating evidence demonstrated that HPVs modulate TLR expression and interfere with TLR signaling pathways, leading to persistent viral infection and carcinogenesis. This review summarizes current knowledge on the roles of TLR during HPV infection, focusing on TLR recognition, modulation of TLR expression and signaling, regulatory receptors involved in TLR signaling, and cross-talk of TLRs with antimicrobial peptides. Immunotherapeutic strategies based on TLR agonists have emerged to be one of the novel promising avenues in treatment of HPV-associated diseases in the future.

Dendritic cells and vaccine design for sexually-transmitted diseases

Dendritic cells (DCs) are major antigen presenting cells (APCs) that can initiate and control host immune responses toward either immunity or tolerance. These features of DCs, as immune orchestrators, are well characterized by their tissue localizations as well as by their subset-dependent functional specialties and plasticity. Thus, the level of protective immunity to invading microbial pathogens can be dependent on the subsets of DCs taking up microbial antigens and their functional plasticity in response to microbial products, host cellular components and the cytokine milieu in the microenvironment. Vaccines are the most efficient and cost-effective preventive medicine against infectious diseases. However, major challenges still remain for the diseases caused by sexually-transmitted pathogens, including HIV, HPV, HSV and Chlamydia. We surmise that the establishment of protective immunity in the female genital mucosa, the major entry and transfer site of these pathogens, will bring significant benefit for the protection against sexually-transmitted diseases. Recent progresses made in DC biology suggest that vaccines designed to target proper DC subsets may permit us to establish protective immunity in the female genital mucosa against sexually-transmitted pathogens.

Endobiont viruses sensed by the human host - beyond conventional antiparasitic therapy

Wide-spread protozoan parasites carry endosymbiotic dsRNA viruses with uncharted implications to the human host. Among them, Trichomonas vaginalis, a parasite adapted to the human genitourinary tract, infects globally ∼250 million each year rendering them more susceptible to devastating pregnancy complications (especially preterm birth), HIV infection and HPV-related cancer. While first-line antibiotic treatment (metronidazole) commonly kills the protozoan pathogen, it fails to improve reproductive outcome. We show that endosymbiotic Trichomonasvirus, highly prevalent in T. vaginalis clinical isolates, is sensed by the human epithelial cells via Toll-like receptor 3, triggering Interferon Regulating Factor -3, interferon type I and proinflammatory cascades previously implicated in preterm birth and HIV-1 susceptibility. Metronidazole treatment amplified these proinflammatory responses. Thus, a new paradigm targeting the protozoan viruses along with the protozoan host may prevent trichomoniasis-attributable inflammatory sequelae.

Treatment failure in patients with HPV 16-induced vulvar intraepithelial neoplasia: understanding different clinical responses to immunotherapy

Failure of the immune system to launch a strong and effective immune response to high-risk HPV is related to viral persistence and the development of anogenital (pre)malignant lesions such as vulvar intraepithelial neoplasia (VIN). Different forms of immunotherapy, aimed at overcoming the inertia of the immune system, have been developed and met with clinical success. Unfortunately these, in principal successful, therapeutic approaches also fail to induce clinical responses in a substantial number of cases. In this review, the authors summarize the traits of the immune response to HPV in healthy individuals and in patients with HPV-induced neoplasia. The potential mechanisms involved in the escape of HPV-induced lesions from the immune system indicate gaps in our knowledge. Finally, the interaction between the immune system and VIN is discussed with a special focus on the different forms of immunotherapy applied to treat VIN and the potential causes of therapy failure. The authors conclude that there are a number of pre-existing conditions that determine the patients' responsiveness to immunotherapy. An immunotherapeutic strategy in which different aspects of immune failure are attacked by complementary approaches, will improve the clinical response rate.

Polymorphisms in Toll-like receptor 3 confer natural resistance to human herpes simplex virus type 2 infection

Lack of Toll-like receptor 3 (TLR3) functional activity predisposes children to human herpesvirus 1 (HSV-1) encephalitis. In this study, we have investigated whether there is any link between TLR3 and adult HSV-2 infection by studying genetic variations in TLR3. The frequency of four single-nucleotide polymorphisms (SNPs) in the TLR3 gene in 239 patients with genital HSV-2 infection and 162 healthy controls, as well as the impact of these variants on TLR3 gene-expression levels, were compared. Two SNPs in the TLR3 gene (rs13126816 and rs3775291) were associated with a reduced incidence of HSV-2 infection. The minor allelic variants at both rs13126816 and rs3775291 were more common among healthy HSV-2-seronegative subjects than among HSV-2-infected individuals. This was even more apparent in HSV-1-seronegative individuals. There was, however, no association between any of the four TLR3 SNPs and HSV-2 disease severity, as they were expressed at similar proportions in asymptomatic and symptomatic HSV-2-infected patients alike. Furthermore, when assessing TLR3 mRNA expression in a limited number of HSV-2-infected individuals, we found that individuals carrying the homozygous genotypes for the minor alleles had significantly higher levels of TLR3 mRNA expression in peripheral blood mononuclear cells in response to HSV-2 stimulation than individuals that were homozygous for the major allele variants. Taken together, these results suggest that genetic variations in TLR3 may affect the susceptibility to HSV-2 infection in humans.

Uterine epithelial cells specifically induce interferon-stimulated genes in response to polyinosinic-polycytidylic acid independently of estradiol

Interferon β (IFNβ) is an antiviral cytokine secreted in response to pathogenic exposure that creates a restrictive intracellular environment through the action of downstream interferon-stimulated genes (ISG). The objective of this study was to examine the expression of IFNβ and ISG in both human uterine epithelial cells (UEC) and the ECC-1 uterine epithelial cell line and determine if expression changes with TLR stimulation and hormone exposure. Stimulation of primary uterine epithelial cells and ECC-1 cells with the TLR3 agonist poly (I:C) induced the mRNA expression of IFNβ, MxA, OAS2 and PKR. Other TLR agonists including imiquimod and CpG had no effect on either IFNβ or ISG expression. In contrast to ECC-1 cell responses which were slower, maximal IFNβ upregulation in UEC occurred 3 hours post-stimulation and preceded the ISG response which peaked approximately 12 hours after poly (I:C) exposure. Unexpectedly, estradiol, either alone or prior to treatment with poly (I:C), had no effect on IFNβ or ISG expression. Blockade of the IFN receptor abrogated the upregulation of MxA, OAS2 and PKR. Furthermore, neutralizing antibodies against IFNβ partially inhibited the upregulation of all three ISG. Estradiol, directly and in the presence of poly (I:C) had no effect on IFNβ and ISG expression. These results indicate that uterine epithelial cells are important sentinels of the innate immune system and demonstrate that uterine epithelial cells are capable of mounting a rapid IFN-mediated antiviral response that is independent of estradiol and is therefore potentially sustained throughout the menstrual cycle to aid in the defense of the uterus against potential pathogens.

Targeting pattern recognition receptors in cancer immunotherapy

Pattern recognition receptors (PRRs) are known for many years for their role in the recognition of microbial products and the subsequent activation of the immune system. The 2011 Nobel Prize for medicine indeed rewarded J. Hoffmann/B. Beutler and R. Steinman for their revolutionary findings concerning the activation of the immune system, thus stressing the significance of understanding the mechanisms of activation of the innate immunity. Such immunostimulatory activities are of major interest in the context of cancer to induce long-term antitumoral responses. Ligands for the toll-like receptors (TLRs), a well-known family of PRR, have been shown to have antitumoral activities in several cancers. Those ligands are now undergoing extensive clinical investigations both as immunostimulant molecules and as adjuvant along with vaccines. However, when considering the use of these ligands in tumor therapy, one shall consider the potential effect on the tumor cells themselves as well as on the entire organism. Recent data indeed demonstrate that TLR activation in tumor cells could trigger both pro- or antitumoral effect depending on the context. This review discusses this balance between the intrinsic activation of PRR in tumor cells and the extrinsic microenvironment activation in term of overall effect of PRR ligands on tumor development. We review recent advances in the field and underline appealing prospects for clinical development of PRR agonists in the light of our current knowledge on their expression and activation.

Menstrual cycle influences Toll-like receptor responses

BACKGROUND

Toll-like receptors (TLRs) are pattern recognition receptors that play an important role as mediators of innate immunity. Human studies have shown changes in endometrial TLR expression during the menstrual cycle and during pregnancy. Our objective was to measure peripheral TLR activity over the course of the menstrual cycle.

METHODS

We recruited 11 healthy females, and using ELISA we measured sex hormone levels and IL-1β, IL-6, IL-8 and TNF-α following stimulation of whole blood with different TLR agonists during follicular, and early and late luteal phases of the menstrual cycle.

RESULTS

During the follicular phase, we observed lower levels of IL-6 and TNF-α following stimulation with the TLR2 agonist HKLM when compared with the early luteal phase; lower levels of IL-1β, IL-6 and TNF-α following stimulation with the TLR4 agonist LPS, and lower levels of IL-1β and TNF-α following stimulation with the TLR5 agonist flagellin. Decreased IL-6 levels in the late compared to the early luteal phase were also observed following stimulation with the TLR5 agonist flagellin. Compared with the follicular phase, the late luteal phase of the cycle resulted in decreased levels of IL-1β and TNF-α following stimulation with the TLR1/TLR2 agonist Pam3CSK and the TLR6/TLR2 agonist FSL1, as well as decreased levels of TNF-α following stimulation with the TLR8 agonist ssRNA40. There were no differences in cytokine release across the menstrual cycle following stimulation with the TLR3 agonist polyriboinosinic polyribocytidylic acid, or the TLR7 agonist Imiquimod.

CONCLUSION

This study is the first to demonstrate that TLR responsivity in peripheral blood fluctuates throughout the menstrual cycle.

Primary human epithelial cell culture system for studying interactions between female upper genital tract and sexually transmitted viruses, HSV-2 and HIV-1

Evidence from clinical and epidemiological studies indicates that women are disproportionately susceptible to sexually transmitted viral infections. To understand the underlying biological basis for this increased susceptibility, more studies are needed to examine the acute events in the female reproductive tract following exposure to viruses during sexual transmission. The epithelial lining of the female reproductive tract is the primary barrier that sexually transmitted viruses, such as HIV-1 and HSV-2 need to infect or traverse, in order to initiate and establish productive infection. We have established an ex-vivo primary culture system to grow genital epithelial cells from upper reproductive tract tissues of women. Using these cultures, we have extensively examined the interactions between epithelial cells of the female genital tract and HSV-2 and HIV-1. In this review, we describe in detail the experimental protocol to grow these cultures, monitor their differentiation and inoculate with HSV-2 and HIV-1. Prospective use of these cultures to re-create the microenvironment in the reproductive tract is discussed.

Changes in the expression of Toll-like receptors in the chicken testis during sexual maturation and Salmonella infection

Rooster infertility is a major concern in the poultry industry and chicken male reproductive organs are the infectious tissues of various pathogenic microorganisms. Protection of the chicken male reproductive organs from pathogens is therefore an essential aspect of reproductive physiology. Recently Toll-like receptors (TLRs) have been identified as one of the key components of innate immunity in vertebrate species and have been reported to be expressed in the reproductive organs in various female species, including the chicken. However, mechanisms of antimicrobial protection of male reproductive organs mediated by TLRs are poorly understood. The objectives of this study were to determine the expression profile of the entire family of the ten chicken TLR genes in the chicken testis, to investigate whether sexual maturation affects their testicular mRNA abundance and to determine the changes in their expression levels in response to Salmonella enteritidis (SE) infection. RNA was extracted from the testis of healthy pre-pubertal, sexually mature and aged birds, and from sexually mature SE infected birds. RT-PCR analysis revealed that all TLRs, apart from TLR1-1 (TLR6), were expressed in the chicken testis. Quantitative real-time PCR analysis revealed that the testicular mRNA abundance of certain TLRs was developmentally regulated with respect to sexual maturation, while SE infection resulted in a significant induction of TLR2-1, 4, 5, 15 and 21 in the testis of sexually mature birds compared, to healthy birds of the same age. These findings provide strong evidence to suggest a key role of TLRs in the innate immune responses of chicken testis against Salmonella colonization.

Expression and function of toll-like receptors in peripheral blood mononuclear cells of patients with polymyalgia rheumatica and giant cell arteritis

OBJECTIVE

To investigate the expression and function of the Toll-like receptor (TLR) family in peripheral blood mononuclear cells (PBMCs) of patients with polymyalgia rheumatica (PMR) and giant cell arteritis (GCA).

METHODS

The authors analysed 70 patients with PMR, 20 with GCA, and 24 healthy controls (HC). TLR expression was assessed by flow cytometry. TLR function was assessed by stimulating PBMCs with specific ligands.

RESULTS

A significantly increased expression of TLR7 in PBMCs of patients with active disease compared with HC was found. Despite increased expression of TLR7, circulating monocytes from patients showed a significantly lower in vitro response to TLR7 agonists. No amino acid substitutions predicted to be functionally damaging were found in TLR7. A normal response to specific TLR7 agonists in patients in complete remission eliminated a genetic defect. TLR expression and function were also affected to some degree in other diseases characterised by a strong acute phase response.

CONCLUSION

These data suggest activation of TLR7 during the active phase of PMR and GCA which resolves with complete disease remission. Whether this finding is the consequence of the marked inflammatory process in these disorders or activation by natural ligands remains to be explored.

Herpes simplex virus type 2 virion host shutoff protein suppresses innate dsRNA antiviral pathways in human vaginal epithelial cells

Viruses that establish persistent infections have evolved numerous strategies to evade host innate antiviral responses. We functionally assessed the role of herpes simplex virus type 2 (HSV-2) virion host shutoff (vhs) protein on innate immune sensing pathways in human vaginal epithelial cells (VK2 ECs). Infection of cells with wild-type (WT) HSV-2 significantly decreased expression of innate immune sensors of viral infection, Toll-like receptor (TLR)2, TLR3, retinoic acid inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (Mda-5), relative to cells infected with a mutant that lacks vhs (vhsB) or mock-infected cells. Transfection with HSV-2 vhs similarly decreased expression of TLR2, TLR3, RIG-I and Mda-5, which was also confirmed in human embryonic kidney (HEK) 293 cells. vhsB infection of VK2 cells caused robust increases in the active form of interferon regulatory factor (IRF)3 and its translocation to the nucleus compared with the WT. Additionally, IRF3 activation by Sendai virus and polyinosinic : polycytidylic acid-induced stimulation of beta interferon (IFN-β) was significantly inhibited in vhs-transfected cells. Overall, our findings provide the first evidence that HSV-2 vhs plays roles in selectively inhibiting TLR3 and RIG-I/Mda-5, as well as TLR2-mediated antiviral pathways for sensing dsRNA and effectively suppresses IFN-β antiviral responses in human vaginal ECs.

TLR9 expression and its role in chemosensitivity to DDP in human cervical cancer cells in vitro

Inflammation and infection play an important role in the pathogenesis of many cancers. Toll-like receptors (TLRs) are a class of pattern recognition receptors that recognize conserved components of microbes and trigger the immune response against invading microorganisms. Toll-like receptor 9 (TLR9) recognizes non-methylated cytosine-phosphateguanosine (CpG) DNA sequences which are the surrogate for viral DNA. TLR9 may react to tumor development and progression during chronic inflammation that involves the tumor microenvironment. In order to study the role of TLR9 in cervical cancer, we analyzed the TLR9 expression in different types of HPV infection cervical cancer cells. Then we detected if CpG sequences influenced the TLR9 expression and the sensitivity to cisplatin (DDP) of these cervical cancer cells in vitro. The expression of TLR9 mRNA and protein in SiHa, Hela and C33A cells was detected by RT-PCR and Western blotting. Real-time PCR was used to examine the TLR9 expression changes induced by CpG. Chemosensitivity of the cervical cancer cells to cisplatin (DDP) was measured by MTT. It was observed that the expression of TLR9 mRNA and protein was increased gradually in SiHa (HPV16+), Hela (HPV18+) and C33A (HPV-) cells. Low doses of CpG increased the TLR9 expression only in C33A (HPV-) cells, but not in SiHa (HPV16+) and Hela (HPV18+) cells. Furthermore, low dose of CpG significantly increased the sensitivity of C33A (HPV-) cells, but not that of SiHa (HPV16+) and Hela (HPV18+) cells. These results indicated that TLR9 may serve as a protective agent in HPV negative cervical cancer cells. It was concluded that TLR9 could improve the sensitivity to DDP in HPV negative cervical cancer cells and might represent a potential therapeutic option in clinical practice.

Human papillomavirus deregulates the response of a cellular network comprising of chemotactic and proinflammatory genes

Despite the presence of intracellular pathogen recognition receptors that allow infected cells to attract the immune system, undifferentiated keratinocytes (KCs) are the main targets for latent infection with high-risk human papilloma viruses (hrHPVs). HPV infections are transient but on average last for more than one year suggesting that HPV has developed means to evade host immunity. To understand how HPV persists, we studied the innate immune response of undifferentiated human KCs harboring episomal copies of HPV16 and 18 by genome-wide expression profiling. Our data showed that the expression of the different virus-sensing receptors was not affected by the presence of HPV. Poly(I:C) stimulation of the viral RNA receptors TLR3, PKR, MDA5 and RIG-I, the latter of which indirectly senses viral DNA through non-self RNA polymerase III transcripts, showed dampening in downstream signalling of these receptors by HPVs. Many of the genes downregulated in HPV-positive KCs involved components of the antigen presenting pathway, the inflammasome, the production of antivirals, pro-inflammatory and chemotactic cytokines, and components downstream of activated pathogen receptors. Notably, gene and/or protein interaction analysis revealed the downregulation of a network of genes that was strongly interconnected by IL-1β, a crucial cytokine to activate adaptive immunity. In summary, our comprehensive expression profiling approach revealed that HPV16 and 18 coordinate a broad deregulation of the keratinocyte's inflammatory response, and contributes to the understanding of virus persistence.

Expression of toll-like receptors in genital tract tissues from normal and HIV-infected men

PROBLEM

cells of the innate immune system use Toll-like receptors (TLRs) to recognize and respond to invading pathogens. This study was carried out to characterize TLR expression in the human male genital tract, an initial infection site for several sexually transmitted pathogens.

METHOD OF STUDY

immunohistochemistry was used to detect expression of TLRs 1-9 in genital tract tissues from HIV(-) and HIV(+) men.

RESULTS

in HIV(-) men, TLR1(+) leukocytes were detected throughout the genital tract. Leukocytes in the penile urethra also expressed TLRs2, 3, 5, 7 and 9. Epithelial cells in most tissues did not express TLRs; exceptions were the prostate, where TLRs3 and 8 were observed on the apical surface of luminal epithelial cells, and the penile urethra, where epithelial cells expressed TLR9. In genital tissues from HIV(+) men with AIDS, few TLR(+) cells were detected.

CONCLUSION

cells in the male genital tract can express a variety of TLRs. The penile urethra contained the highest number of TLR(+) cells, indicating that this tissue plays a major role in the innate immune defense of the male genital tract. Overall, TLR expression was reduced in genital tissues from HIV(+) men.