The Bacterial Product Violacein Exerts an Immunostimulatory Effect Via TLR8.

Violacein, an indole-derived, purple-colored natural pigment isolated from Chromobacterium violaceum has shown multiple biological activities. In this work, we studied the effect of violacein in different immune cell lines, namely THP-1, MonoMac 6, ANA-1, Raw 264.7 cells, as well as in human peripheral blood mononuclear cells (PBMCs). A stimulation of TNF-α production was observed in murine macrophages (ANA-1 and Raw 264.7), and in PBMCs, IL-6 and IL-1ß secretion was detected. We obtained evidence of the molecular mechanism of activation by determining the mRNA expression pattern upon treatment with violacein in Raw 264.7 cells. Incubation with violacein caused activation of pathways related with an immune and inflammatory response. Our data utilizing TLR-transfected HEK-293 cells indicate that violacein activates the human TLR8 (hTLR8) receptor signaling pathway and not human TLR7 (hTLR7). Furthermore, we found that the immunostimulatory effect of violacein in PBMCs could be suppressed by the specific hTLR8 antagonist, CU-CPT9a. Finally, we studied the interaction of hTLR8 with violacein in silico and obtained evidence that violacein could bind to hTLR8 in a similar fashion to imidazoquinoline compounds. Therefore, our results indicate that violacein may have some potential in contributing to future immune therapy strategies.

Tolerance and sorption of Bromacil and Paraquat by thermophilic cyanobacteria Leptolyngbya 7M from Costa Rican thermal springs.

We studied the adsorption ability and tolerance of the thermophilic filamentous cyanobacteria Letolyngbya 7M towards Paraquat and Bromacil. Adsorption isotherms at pH = 7.0 showed an adsorption capacity of 24.4 mg/g and 66.8 mg/g, respectively, and a good fit to the Langmuir model (R2 = 0.97 and 0.99, respectively). To evaluate the effect of both herbicides on photosynthetic pigments and viability of cyanobacteria, cell autoflorescence and esterase activity was determined using flow cytometry. Autofluorescence was less sensitive to changes in cell viability, as it was only slightly reduced at high Paraquat and Bromacil concentrations. Herbicide effect on esterase activity is dose-dependent. Bromacil did not cause a significant effect on either chlorophyll a content or cell viability. This study demonstrates the potential of Leptolyngbya 7M to remove Paraquat and Bromacil herbicides from aqueous solution under laboratory conditions.

Alterations of T-cell surface markers in older women with persistent human papillomavirus infection.

We previously reported decreased lymphocyte proliferative responses among older women with persistent human papillomavirus (HPV) infection. To characterize the phenotype of peripheral lymphocytes associated with persistent HPV infection, we evaluated the expression of different cell surface markers in peripheral blood mononuclear cells (PBMCs) from a case-control study within a 10,049 woman population-based cohort study in Guanacaste, Costa Rica. Women in the cohort aged 46-74 and with HPV results at their 5th year anniversary visit were considered, and all women (n = 87) with persistent HPV infections, all women (n = 196) with transient HPV infections and a random sample of HPV DNA-negative women (n = 261) frequency-matched to cases on age were selected for this study. A median of 3 years after the case-control matching visit, cervical cells were collected for liquid-based cytology and repeat HPV DNA genotyping. Blood was obtained from which PBMCs were extracted and cryopreserved for immunological phenotyping via flow cytometry. Significant increases in risk of HPV persistence were observed for 3 marker subsets indicative of immune cell activation/differentiation. Relative risk estimates were 5.4 (95% CI = 2.2-13.3) for CD69(+)CD4(+), 2.6 (95% CI = 1.2-5.9) for HLADR(+)CD3(+)CD4(+) and 2.3 (95% CI = 1.1-4.7) for CD45RO(+)CD27(-)CD8(+). A significant decrease in HPV persistence was observed for a subset marker indicative of an immature, undifferentiated memory state CD45RO(+)CD27(+)CD4(+) (OR = 0.36; 95% CI = 0.17-0.76). Adjustment for these markers only partially explained the previously reported association between decreased lymphoproliferative responses and persistent HPV infection. Whether phenotypic alterations observed predispose to HPV persistence or result from it should be the focus of future studies.

Elevated systemic levels of inflammatory cytokines in older women with persistent cervical human papillomavirus infection.

BACKGROUND: Defects in lymphoproliferative responses to mitogens/antigens in women >45 years old with a persistent type-specific human papillomavirus (HPV) infection have been reported. METHODS: To determine whether these defects were associated with altered cytokine profiles, plasma and peripheral blood mononuclear cell (PBMC) culture supernatants from 50 cases (oversampled for their reduced lymphoproliferative ability) and 50 uninfected controls (oversampled for their robust lymphoproliferative ability) were examined for 24 cytokines using multiplexed bead-based immunoassays and ELISA. RESULTS: The following plasma cytokines were significantly increased in cases relative to controls (cases versus controls; median pg/mL): interleukin (IL)-6, 393.1 versus 14.5; IL-8, 1,128.5 versus 43.9; tumor necrosis factor-alpha (TNF-alpha), 164.1 versus 9.2; macrophage inflammatory protein-1alpha (MIP-1alpha), 1,368.9 versus 25.5; granulocyte macrophage colony-stimulating factor (GM-CSF), 13.8 versus 7.3; IL-1beta, 8.3 versus 1.6 (all P < 0.0001); and IL-1alpha, 218.2 versus 169.5 (P = 0.02). We focused our analysis on the cytokines IL-6, IL-8, TNF-alpha, and MIP-1alpha due to their high fold change (>10) and highly statistically significant difference between cases and controls. Length of persistence or type of infection (high risk and low risk) did not affect these differences. IL-6, TNF-alpha, and MIP-1alpha levels were also increased in unstimulated PBMC culture supernatants from cases compared with controls (P < 0.05), however, the cytokine levels from phytohemagglutinin-stimulated PBMC culture supernatants were significantly lower in the cases (P < 0.0001). CONCLUSIONS: Persistent HPV infection in older women with evidence of immune deficit is associated with an increase in systemic inflammatory cytokines. IMPACT: Future studies are needed to determine whether the inflammatory profile is age dependent and to examine the role that inflammatory cytokines play in HPV-induced progression from infection to cervical cancer.

Comparison of mRNA and protein measures of cytokines following vaccination with human papillomavirus-16 L1 virus-like particles.

BACKGROUND: mRNA expression signatures are frequently used as surrogate measures of cellular function and pathway changes. Few studies have directly compared results obtained using gene expression and multiplex protein assays for corresponding gene products. METHODS: We used data available from a clinical trial of a human papillomavirus-16 vaccine that tracked gene expression and cytokine/chemokine production by peripheral blood mononuclear cells stimulated in culture with various antigens to evaluate the degree to which gene expression levels reflect observed levels of cytokines/chemokines. Twenty-six women enrolled in a phase II clinical trial of a human papillomavirus-16 vaccine were evaluated for gene expression (using the Affymetrix Human Genome Focus Array) and cytokine/chemokine levels (using a bead-based 22-plex cytokine assay developed by Linco Research, Inc.) before and after vaccination. RESULTS: Our results suggest the presence of a wide range of correlations between mRNA expression and secreted protein levels. The strongest correlation was observed for IFN-gamma (R = 0.90 overall levels; R = 0.69 when vaccine induced changes were evaluated). More modest overall correlations ranging from 0.40 to 0.80 were observed for MIP1A, IP10, TNF-alpha, MCP1, IL-2, GM-CSF, IL-5, RANTES, and IL-8. Weaker or no correlation was observed between gene expression and protein levels for the remaining cytokines/chemokines evaluated. CONCLUSION: The degree of correlation between gene expression and protein levels varied among different cytokines/chemokines. IMPACT: Researchers should be cautious when using mRNA expression array results as a proxy for protein levels using existing technologies.

Gene expression patterns induced by HPV-16 L1 virus-like particles in leukocytes from vaccine recipients.

Human papillomavirus (HPV) virus-like particle (VLP) vaccines were recently licensed. Although neutralizing Ab titers are thought to be the main effectors of protection against infection, early predictors of long-term efficacy are not yet defined and a comprehensive understanding of innate and adaptive immune responses to vaccination is still lacking. Here, microarrays were used to compare the gene expression signature in HPV-16 L1 VLP-stimulated PBMCs from 17 vaccine and 4 placebo recipients before vaccination and 1 mo after receiving the second immunization. Vaccination with a monovalent HPV-16 L1 VLP vaccine was associated with modulation of genes involved in the inflammatory/defense response, cytokine, IFN, and cell cycle pathways in VLP-stimulated PBMCs. Additionally, there was up-regulation of probesets associated with cytotoxic (GZMB, TNFSF10) and regulatory (INDO, CTLA4) activities. The strongest correlations with neutralizing Ab titers were found for cyclin D2 (CCND2) and galectin (LGALS2). Twenty-two differentially expressed probesets were selected for confirmation by RT-PCR in an independent sample set. Agreement with microarray data was seen for more than two-thirds of these probesets. Up-regulation of immune/defense response genes by HPV-16 L1 VLP, in particular, IFN-induced genes, was observed in PBMCs collected before vaccination, with many of these genes being further induced following vaccination. In conclusion, we identified important innate and adaptive response-related genes induced by vaccination with HPV-16 L1 VLP. Further studies are needed to identify gene expression signatures of immunogenicity and long-term protection with potential utility in prediction of long-term HPV vaccination outcomes in clinical trials.

Evaluation of systemic and mucosal anti-HPV16 and anti-HPV18 antibody responses from vaccinated women.

Ideal methods to monitor HPV neutralizing antibodies induced by vaccination have not been established yet. Here, we evaluated systemic and cervical antibody levels induced by HPV16/18 AS04-adjuvanted vaccine (GlaxoSmithKline Biologicals) using a secreted alkaline phosphatase neutralization assay (SEAP-NA) and enzyme-linked immunosorbent assay (ELISA). Serum and cervical secretions from 50 vaccinated women were used to assess (1) overall assay reproducibility; (2) inter-assay and inter-specimen correlation; (3) correlations between month 1 and month 12 titers. Strong correlations between SEAP-NA and ELISA were observed (serum anti-HPV16/18, rho=0.91/0.85; cervix anti-HPV16/18, rho=0.84/0.89). Systemic and cervical antibody measures also correlated well (rho range: 0.64-0.75); except at mid-cycle (rho range: 0.28-0.65). Correlations between antibody levels at 1 and 12 months following the start of vaccination were poor (rho range: 0.16-0.38). In conclusion, HPV16/18 VLP-based ELISA is a reliable and valid method to monitor anti-HPV16/18 neutralizing potential for the first year following vaccination; however, additional studies will be required to better define the effects of the time on cycle and patterns of antibody response over time following vaccination.

Cytokine and chemokine profiles following vaccination with human papillomavirus type 16 L1 Virus-like particles.

To determine the systemic cytokine pattern induced by vaccination with human papillomavirus (HPV) L1 virus-like particles (VLP), we analyzed 22 different cytokines in culture supernatants of L1 VLP-stimulated peripheral blood mononuclear cells from vaccine (n = 19) and placebo (n = 7) recipients at months 0 and 2 after vaccination, using a multiplex cytokine bead array. In vaccine recipients, incubation with L1 VLP in vitro led to a statistically significant increase in production of Th1 (granulocyte-macrophage colony-stimulating factor, interleukin-2 [IL-2], gamma interferon; P < 0.0007) and Th2 (IL-4, IL-5, IL-10, IL-13; P < 0.0017) cytokines and the chemokine IP-10 (P = 0.0021) at month 2 after immunization, compared to levels seen prior to vaccination. These responses were not seen in placebo recipients. Cytokine and neutralizing antibody responses to vaccination followed the same pattern, with the highest antibody responses seen for subjects with higher cytokine responses. Cytokine profiling studies using samples from efficacy trials may provide important information about discriminators of long-term protection against HPV.

Noninfectious papilloma virus-like particles inhibit HIV-1 replication: implications for immune control of HIV-1 infection by IL-27.

Human papilloma virus (HPV)-like particles (VLPs) have been used as a vaccine to prevent HPV infection. Recent studies demonstrate that VLPs bind to dendritic cells and induce the expression of antiviral cytokines such as interferon-alpha (IFN-alpha), interleukin-10 (IL-10) and IFN-gamma. In the present study, we evaluated the effect of VLPs on HIV-1 replication in peripheral blood mononuclear cells (PBMCs), CD4+ T cells, and macrophages. Here, we show that VLPs suppress the replication of both X4 and R5 HIV-1 without affecting the expression of CD4, CXCR4, and CCR5. Soluble factor(s) released by PBMCs and macrophages on VLPs treatment inhibited HIV-1 replication. To determine the inhibitory factors, DNA microarray analysis was performed using VLP-treated PBMCs and macrophages. VLPs induced the genes associated with IFN induction, immune responses, and antiviral responses, among with the recently described cytokine IL-27. Subsequently, IL-27 was found to be a potent inhibitor of HIV-1 replication in PBMCs, CD4+ T cells, and macrophages. Taken together, our studies identify a novel role of IL-27 in restricting HIV-1 replication and suggest that further examination of the inhibitory property of IL-27 may pave the way for a novel therapy for HIV-1 infection.

Persistent human papillomavirus infection is associated with a generalized decrease in immune responsiveness in older women.

The development of cervical cancer and its precursors are linked to persistent infection with oncogenic types of human papillomavirus (HPV). Host immune responses seem to be determinants of risk for this disease. However, little is known about the immunologic determinants of HPV persistence. Here, we examined the association between lymphoproliferative responses to antigens/mitogens and persistent HPV infection in women older than 45 years. Women included in this study were participants in a 10,000-woman population-based cohort study of cervical neoplasia in Costa Rica. Women older than 45 years and HPV DNA positive at a screening visit were selected as cases (n = 283). We selected a comparably sized control group of HPV DNA-negative women, matched to cases on age and time since enrollment (n = 261). At an additional clinical visit, women were cytologically and virologically rescreened, and cervical and blood specimens were collected. Proliferative responses to phytohemagglutinin (PHA), influenza virus (Flu), and HPV16 virus-like particle (VLP) were lower among women with persistent HPV infection [median counts per minute (cpm): 72,849 for PHA, 1,241 for Flu, and 727 for VLP] than for the control group (median cpm: 107,049 for PHA, 2,111 for Flu, and 2,068 for VLP). The decreases were most profound in women with long-term persistence and were only observed for the oldest age group (>/=65 years). Our results indicate that an impairment in host immunologic responses is associated to persistent HPV infection. The fact that effects were evident for all studied stimuli is suggestive of a generalized effect.

Cellular immune responses to HPV-18, -31, and -53 in healthy volunteers immunized with recombinant HPV-16 L1 virus-like particles.

Human papillomavirus-like particles (HPV VLP) are candidate vaccines that have shown to be efficacious in reducing infection and inducing robust antiviral immunity. Neutralizing antibodies generated by vaccination are largely type-specific, but little is known about the type-specificity of cellular immune responses to VLP vaccination. To determine whether vaccination with HPV-16 L1VLP induces cellular immunity to heterologous HPV types (HPV-18, HPV-31, and HPV-53), we examined proliferative and cytokine responses in vaccine (n=11) and placebo (n=5) recipients. Increased proliferative and cytokine responses to heterologous types were observed postvaccination in some individuals. The proportion of women responding to heterologous types postvaccination (36%-55%) was lower than that observed in response to HPV-16 (73%). Response to HPV-16 VLP predicted response to other types. The strongest correlations in response were observed between HPV-16 and HPV-31, consistent with their phylogenetic relatedness. In summary, PBMC from HPV-16 VLP vaccine recipients can respond to L1VLP from heterologous HPV types, suggesting the presence of conserved T cell epitopes.

DNAse treatment following thawing of cryopreserved PBMC is a procedure suitable for lymphocyte functional studies.

Testing freshly isolated PBMC is not practical for immune monitoring analysis in large clinical trials or natural history studies. Thus, cryopreserved PBMC represent a more practical alternative. However, cell clumping is a common problem following thawing of PBMC isolated from blood that was previously transported and stored. Cell clumping leads to loss of cells, and could affect cell function and/or phenotype. The development and validation of procedures that prevent cell clumping and preserve cell function and surface marker expression levels are necessary to allow evaluation of immune function and phenotype in cryopreserved samples from clinical studies. The incorporation of a DNAse treatment step in the standard thawing procedure efficiently avoided clump formation, and did not result in detectable changes in cell viability, expression of standard leukocyte surface markers or two key parameters of immune function, proliferation and cytokine induction in response to a variety of common stimuli. Therefore, this procedure seems suitable for standard immunologic assays.

Role of DC-SIGN in the activation of dendritic cells by HPV-16 L1 virus-like particle vaccine.

Dendritic cell-specific intercellular adhesion molecule-grabbing non-integrin (DC-SIGN), a specific C-type lectin expressed on DC, binds and transmits different pathogens to susceptible cells. In the present study, we examined the role of DC-SIGN in the capture of human papillomavirus (HPV) pseudovirions and activation of DC. We demonstrate that HPV virus-like particles (VLP) bind to DC-SIGN expressed on transfected Raji cells and that antibodies against DC-SIGN block this interaction. DC take up VLP, which activate expression of costimulatory markers and cytokines/chemokines. Although our results indicate that DC-SIGN is not the major receptor for VLP in DC, this interaction contributes to the activation of DC surface antigens (HLA class I) and of various cytokines/chemokines, particularly TNF-alpha, IL-6, and RANTES. Induction of these markers in DC by VLP was significantly abrogated when binding to DC-SIGN was blocked by anti-DC-SIGN antibodies. These results suggest that DC-SIGN has a functional role in DC activation induced by HPV-16 L1-VLP, and thus highlight new aspects of DC interactions with HPV VLP.

Quantitative structure-activity relationship of sesquiterpene lactones as inhibitors of the transcription factor NF-kappaB.

Sesquiterpene lactones (SLs) are the active compounds of a variety of traditionally used medicinal plants from the Asteraceae family. They are known to possess a considerable antiinflammatory activity in different inflammation models. They inhibit the transcription factor NF-kappaB probably by alkylating cysteine38 in the DNA binding domain of the p65 subunit. Here we investigate a set of 103 different sesquiterpene lactones representing 6 structural groups (44 germacranolides, 16 heliangolides, 22 guaianolides, 9 pseudoguaianolides, 2 hypocretenolides, 10 eudesmanolides) for their NF-kappaB inhibiting properties and the resulting IC(100)-values were submitted to a QSAR study. Properties important for the inhibition potency are discussed for the whole data set and for subsets of the different structural classes.

Sesquiterpene lactones inhibit luciferase but not beta-galactosidase activity in vitro and ex vivo.

Reporter enzymes such as firefly luciferase or beta-galactosidase of Escherichia coli are frequently used to study transcriptional activity of genes and to investigate the effects of novel compounds on gene or transcription factor activity. It is generally assumed that the activity of these enzymes is unaffected by the treatment conditions. Therefore, this factor is not considered when interpreting the data obtained. Biologically active compounds such as sesquiterpene lactones (SLs) have also been tested in reporter gene assays for their influence on gene expression. Here we show in in vitro and ex vivo experiments that SLs inhibit firefly luciferase activity probably by direct targeting of the enzyme while beta-galactosidase remains almost completely unaffected. The loss of luciferase activity after SL treatment could be an effect of their sulfhydryl-modifying potency and the subsequent alteration of the enzyme's tertiary structure. These results demonstrate that the effect of the test substance on the reporter enzyme used should be taken into consideration when the transcriptional effect of novel compounds is investigated.

Evaluation of Tanacetum larvatum for an anti-inflammatory activity and for the protection against indomethacin-induced ulcerogenesis in rats.

Oral administration of the chloroform extract from Tanacetum larvatum (Griseb. ex Pant.) Kanitz caused a dose-dependent anti-inflammatory effect in the carrageenan-induced rat paw oedema test. The obtained anti-inflammatory effect was 8.6, 32.8, 37.0 and 49.5% for the extract doses of 25, 50, 100 and 200mg/kg, respectively, being statistically significant at a dose of 50mg/kg. Indomethacin had a strong anti-inflammatory effect of 73.4% at a dose of 8mg/kg, but large gastric lesions were detected. When the plant extract in the highest tested dose (200mg/kg) was concomitantly given with indomethacin, the anti-inflammatory effect was slightly enhanced, but the gastric lesions were significantly reduced. The anti-inflammatory and anti-ulcer activity may be mainly due to the inhibition of DNA binding of the transcription factor NF-kappaB by components of the plant extract. This was proven in an electrophoretic mobility shift assay at a concentration of 50microg/ml. Due to its anti-inflammatory as well as anti-ulcer effects, Tanacetum larvatum should especially be used combined with those drugs that are known both for their strong anti-inflammatory activities and the ulcerogenic side effects such as NSAIDs.

Effect of sesquiterpene lactones on the expression of the activation marker CD69 and of IL-2 in T-lymphocytes in whole blood.

We used flow cytometry to investigate the inhibitory effect of sesquiterpene lactones (SLs) on T-cell activation measured by the expression of its early marker CD69, and on interleukin (IL)-2, a mediator of activation, in whole blood. SLs are biologically active compounds found especially in plants from the Asteraceae family. Overnight treatment of blood with these substances led to the inhibition of CD69 and IL-2 expression. Interestingly, bifunctional SLs showed a weaker activity than monofunctional substances, which is in contradiction with the data obtained so far, using other biological test systems. Additionally, SLs did not completely inhibit CD69 or IL-2 expression. We also determined their toxicity and observed only a low effect. Up to now, studies on cytotoxicity have only been performed using cultured cell lines. From these results it may be supposed that these natural compounds preferentially show toxic effects towards transformed cell lines. Altogether, the results demonstrated that SLs effectively inhibit the activation of the T-lymphocyte response in whole blood and proved the utility of a whole blood system in studying their biological effects.

Guaianolides from Viguiera gardneri inhibit the transcription factor NF-kappaB.

Five guaianolides and a germacrolide were isolated from the leaf rinse extract of Viguiera gardneri (Asteraceae), together with known compounds. All compounds were detected in glandular trichomes collected from the leaves and were analyzed by HPLC. Structure elucidation was based on the analysis of spectroscopic data. Low energy conformations were obtained by quantum mechanical calculations. Three closely related guaianolides which were isolated as the main compounds were studied for their anti-inflammatory activity using the transcription factor NF-kappaB as molecular target. NF-kappaB DNA binding was inhibited at sesquiterpene lactones concentrations of 10 or 50 microM.