CpG oligodeoxynucleotides block human immunodeficiency virus type 1 replication in human lymphoid tissue infected ex vivo

MiR-155 Negatively Regulates Anti-Viral Innate Responses among HIV-Infected Progressors

HIV infection impairs host immunity, leading to progressive disease. An anti-retroviral treatment efficiently controls viremia but cannot completely restore the immune dysfunction in HIV-infected individuals. Both host and viral factors determine the rate of disease progression. Among the host factors, innate immunity plays a critical role; however, the mechanism(s) associated with dysfunctional innate responses are poorly understood among HIV disease progressors, which was investigated here. The gene expression profiles of TLRs and innate cytokines in HIV-infected (LTNPs and progressors) and HIV-uninfected individuals were examined. Since the progressors showed a dysregulated TLR-mediated innate response, we investigated the role of TLR agonists in restoring the innate functions of the progressors. The stimulation of PBMCs with TLR3 agonist-poly:(I:C), TLR7 agonist-GS-9620 and TLR9 agonist-ODN 2216 resulted in an increased expression of IFN-α, IFN-β and IL-6. Interestingly, the expression of IFITM3, BST-2, IFITM-3, IFI-16 was also increased upon stimulation with TLR3 and TLR7 agonists, respectively. To further understand the molecular mechanism involved, the role of miR-155 was explored. Increased miR-155 expression was noted among the progressors. MiR-155 inhibition upregulated the expression of TLR3, NF-κB, IRF-3, TNF-α and the APOBEC-3G, IFITM-3, IFI-16 and BST-2 genes in the PBMCs of the progressors. To conclude, miR-155 negatively regulates TLR-mediated cytokines as wel l as the expression of host restriction factors, which play an important role in mounting anti-HIV responses; hence, targeting miR-155 might be helpful in devising strategic approaches towards alleviating HIV disease progression.

Potential role of EBV and Toll-like receptor 9 ligand in patients with systemic lupus erythematosus

SLE is a multisystem autoimmune disease characterized by multiple immunological abnormalities including production of autoantibodies. While the etiology of SLE is largely unknown, it is generally accepted that both genetic and environmental factors contribute to disease risk and immune dysregulation. Production of IFN-α is important for protecting the host against infections; however, over stimulation of innate immune pathways can induce autoimmune disease. Environmental factors, particularly Epstein-Barr virus (EBV), have been proposed to play an important role in SLE disease. Improper engagement of Toll-like receptor (TLR) pathways by endogenous or exogenous ligands may lead to the initiation of autoimmune responses and tissue injury. EBV is shown to be a potent stimulant of IFN-α by TLR signaling cascades. Given the highlighted role of IFN-α in SLE pathogenesis and potential role of EBV infection in this disease, the present study is aimed at exploring the in vitro effects of EBV infection and CPG (either alone or in combination) on IFN-α. We also examined the expression level of CD20 and BDCA-4 and CD123 in PBMCs in 32 SLE patients and 32 healthy controls. Our results showed PBMCs treated with CPG-induced higher levels of IFN-α and TLR-9 gene expression fold change compared to cells treated with either EBV or EBV-CPG. Moreover, PBMCs treated with CPG produced significantly higher IFN-α concentration in supernatant compared to cells treated with EBV but not EBV-CPG. Our results further highlight the potential role of EBV infection and TLRs in SLE patients although more studies are warranted to ascertain the global imprint that EBV infection can have on immune signature in patients with SLE.

Carrier-free micellar CpG interacting with cell membrane for enhanced immunological treatment of HIV-1

Unmethylated CpG motifs activate toll-like receptor 9 (TLR9), leading to sequence- and species-specific immune stimulation. Here, we engineered a CpG oligodeoxyribonucleotide (ODN) with multiple hydrophobic moieties, so-called lipid-modified uracil, which resulted in a facile micelle formation of the stimulant. The self-assembled CpG nanostructure (U4CpG) containing the ODN 2216 sequence was characterized by various spectroscopic and microscopic methods together with molecular dynamics simulations. Next, we evaluated the nano-immunostimulant for enhancement of anti-HIV immunity. U4CpG treatment induced activation of plasmacytoid dendritic cells (pDCs) and natural killer (NK) cells in healthy human peripheral blood, which produced type I interferons (IFNs) and IFN-γ in human peripheral blood mononuclear cells (PBMCs). Moreover, we validated the activation and promotion efficacy of U4CpG in patient-derived blood cells, and HIV-1 spread was significantly suppressed by a low dosage of the immunostimulant. Furthermore, U4CpG-treated PBMC cultured medium elicited transcription of latent HIV-1 in U1 cells indicating that U4CpG reversed HIV-1 latency. Thus, the functions of U4CpG in eradicating HIV-1 by enhancing immunity and reversing latency make the material a potential candidate for clinical studies dealing with viral infection.

Effects of Adjuvants on HIV-1 Envelope Glycoprotein SOSIP Trimers In Vitro

Native-like, soluble, recombinant SOSIP trimers of various designs and based on several env genes of human immunodeficiency virus type 1 (HIV-1) are being tested as immunogens in different animal models. These experiments almost always involve coformulating the trimers with an adjuvant to boost the magnitude of the immune responses. One factor relevant to the choice of an adjuvant is that it should not physically damage the immunogen or impede its ability to present relevant epitopes. As examples, an adjuvant formulation that includes harsh detergents could disrupt the structural integrity of a trimer, and any charged compounds in the formulation could bind to countercharged regions of the trimer and physically occlude nearby epitopes. While a few adjuvants have been tested for their potential effects on SOSIP trimers in vitro, there has been no systematic study. Here, we have assessed how nine different adjuvants of various compositions affect SOSIP trimers of the BG505 and B41 genotypes. We used negative-stain electron microscopy, thermal denaturation, and gel electrophoresis to evaluate effects on trimer integrity and immunoassays to measure effects on the presentation of various epitopes. We conclude that most of the tested adjuvants are benign from these perspectives, but some raise grounds for concern. An acidified alum formulation is highly disruptive to trimer integrity, and a DNA-based polyanionic CpG oligodeoxynucleotide adjuvant binds to trimers and occludes the trimer apex epitope for the PGT145 neutralizing antibody. The methods described here should be generalizable to protein subunit vaccines targeting various pathogens.

IMPORTANCE Adjuvant formulations increase the magnitude of immune responses to vaccine antigens. They are critically important for formulation of HIV-1 envelope glycoprotein (Env) vaccines intended to induce antibody production, as Env proteins are otherwise only very weakly immunogenic. The HIV-1 vaccine field now uses the well-defined structures of trimeric Env glycoproteins, like SOSIPs, to present multiple known epitopes for broad and potent neutralizing human antibodies in a native-like conformation. Successful adjuvant formulations must not disrupt how the trimers are folded, as that could adversely affect their performance as immunogens. We studied whether the various adjuvants most commonly used in animal experiments affect the integrity of two different SOSIP trimers in vitro. Most adjuvant classes are not problematic, but an aluminum sulfate formulation is highly damaging, as it exposes trimers to acidic pH and a nucleic acid-based adjuvant can bind to the trimer and block access to a key neutralizing epitope.

Donor TLR9 gene tagSNPs influence susceptibility to aGVHD and CMV reactivation in the allo-HSCT setting without polymorphisms in the TLR4 and NOD2 genes

Owing to ethnicity of the population, those best confirmed polymorphisms in the TLR (toll-like receptor)4 and NOD2 genes with significantly prognostic impact on allogeneic hematopoietic SCT (allo-HSCT) seem to be more applicable to Europeans and are nonpolymorphic in the Asian population. The influence of innate immunity gene polymorphisms on the outcomes of allo-HSCT in those populations has been questioned. We evaluated the influence of 10 candidate single nucleotide polymorphisms (SNPs) in the TLR1, TLR2, TLR3, TLR8 and TLR9 genes on the outcomes of allo-HSCT in a Chinese population including 138 pairs of patients and unrelated donors and a second cohort of 102 pairs of patients and HLA-identical sibling donors. We found that two tagSNPs in the TLR9 gene in the donor side, +1174 A/G (rs352139) and +1635 C/T (rs352140), influenced the risk of acute GVHD (aGVHD) and CMV reactivation. Furthermore, the presence of the susceptible haplotype (A-C) in donor may be an informative predicator of worse OS at 5 years compared with those with the G-C and G-T haplotypes (58% vs 82.9%, P=0.024). Our data suggested an unrecognized association between donor TLR9 tagSNPs and the risk of HSCT-related complications in a population without polymorphisms in the TLR4 and NOD2 genes.

Toll-like receptor 9 (TLR9) gene polymorphisms associated with increased susceptibility of human papillomavirus-16 infection in patients with cervical cancer

Objectives

To investigate the association between toll-like receptor 9 ( TLR9) single nucleotide polymorphisms (SNPs) and human papillomavirus (HPV) infection among Chinese Han women with cervical cancer.

Methods

TLR9 –1486 and 2848 SNPs were investigated in patients with cervical cancer and controls using polymerase chain reaction (PCR)-restriction fragment length polymorphism. HPV16 E6 and E7 infections were assessed using PCR.

Results

Of 120 patients with cervical cancer and 100 controls, there was a significant association between TLR9 2848 SNP and cervical cancer risk, but there was no such association with TLR9 –1486 SNP. Frequency of the TLR9 2848 GA genotype was significantly higher in patients with cervical cancer than in controls. There was no statistically significant between-group difference in presence of HPV16 infection. Presence of HPV infection with TLR9 2848 (rs352140) GA/AA genotype increased the risk of cervical cancer 13.8-fold compared with the GG genotype.

Conclusions

The TLR9 2848 G/A polymorphism in Chinese Han women was associated with increased risk of cervical cancer in the presence of HPV16 infection. Further studies are necessary to uncover the functional aspect of this TLR9 2848 polymorphism.

Early inhibitors of human cytomegalovirus: state-of-art and therapeutic perspectives

Human cytomegalovirus (HCMV) infection is associated with severe morbidity and mortality in immunocompromised individuals, mainly transplant recipients and AIDS patients, and is the most frequent cause of congenital malformations in newborn children. To date, few drugs are licensed for the treatment of HCMV infections, most of which target the viral DNA polymerase and suffer from many drawbacks, including long-term toxicity, low potency, and poor bioavailability. In addition, the emergence of drug-resistant viral strains is becoming an increasing problem for disease management. Finally, none of the current anti-HCMV drugs have been approved for the treatment of congenital infections. For all these reasons, there is still a strong need for new anti-HCMV drugs with novel mechanisms of action. The first events of the virus replication cycle, including attachment, entry, immediate-early gene expression, and immediate-early functions—in particular that of Immediate-Early 2 protein—represent attractive targets for the development of novel antiviral compounds. Such inhibitors would block not only the expression of viral immediate-early proteins, which play a key role in the pathogenesis of HCMV infection, but also the host immunomodulation and the changes to cell physiology induced by the first events of virus infection. This review describes the current knowledge on the initial phases of HCMV replication, their validation as potential novel antiviral targets, and the development of compounds that block such processes.

Toll-like receptor expression and activation in astroglia: differential regulation by HIV-1 Tat, gp120, and morphine

In this study, we aimed to determine whether morphine alone or in combination with HIV-1 Tat or gp120 affects the expression of Toll-like receptors (TLRs) by astrocytes and to assess whether TLRs expressed by astrocytes function in the release of inflammatory mediators in vitro. TLR profiling by immunofluorescence microscopy, flow cytometry, in-cell westerns, and RT-PCR showed that subpopulations of astrocytes possessed TLR 2, TLR3, TLR4, and TLR9 antigenicity. Exposure to HIV-1 Tat, gp120, and/or morphine significantly altered the proportion of TLR-immunopositive and/or TLR expression by astroglia in a TLR-specific manner. Subsets of astroglia displayed significant increases in TLR2 with reciprocal decreases in TLR9 expression in response to Tat or gp120 ± morphine treatment. TLR9 expression was also significantly decreased by morphine alone. Exposing astrocytes to the TLR agonists LTA (TLR2), poly I:C (TLR3), LPS (TLR4) and unmethylated CpG ODN (TLR9) resulted in increased secretion of MCP-1/CCL2 and elevations in reactive oxygen species. TLR3 and TLR4 stimulation increased the secretion of TNF-α, IL-6, and RANTES/CCL5, while activation of TLR2 caused a significant increase in nitric oxide levels. The results suggest that HIV-1 proteins and/or opioid abuse disrupt the innate immune response of the central nervous system (CNS) which may lead to increased pathogenicity.

CpG oligodeoxynucleotides protect against the 2009 H1N1 pandemic influenza virus infection in a murine model

The 2009 H1N1 influenza virus pandemic poses a global public health threat, and there is a critical need for antiviral drugs for pandemic control. CpG oligodeoxynucleotides have strong immunostimulatory properties and are expected to be used as prophylactic agents to protect against microbial infections. The present study evaluated the efficacy of synthetic CpG oligodeoxynucleotide (ODN) 1826 against pandemic H1N1 virus infection in a murine model. A single injection of 15 μg ODN 1826 intraperitoneally prior to virus challenge inhibits virus replication in lungs, reduces lung lesions and prevents mortality in mice, indicating CpG ODNs as a possible strategy for future influenza pandemics control.

A novel method for making human monoclonal antibodies

We have developed a B cell immortalization method for low B cell numbers per well using simultaneous B cell stimulation by CpG2006 and B cell infection by Epstein-Barr virus (EBV), followed by an additional CpG2006 and interleukin-2 (IL-2) stimulus. Using this method, immunoglobulin G (IgG)-producing immortalized B cell lines were generated from peripheral blood IgG⁺CD22⁺ B cells with an efficiency of up to 83%. Antibody can already be obtained from the culture supernatant after 3–4 weeks. Moreover, clonality analysis demonstrated monoclonality in 87% of the resulting immortalized B cell lines. Given the high immortalization efficiency and monoclonality rate, evidence is provided that no further subcloning is necessary. An important application of this B cell immortalization method is the characterization of (autoreactive) antibodies from patients with autoimmune disease. This could eventually lead to the identification of new autoantigens, disease markers or targets for therapy.

Phosphothioate oligodeoxynucleotides inhibit Plasmodium sporozoite gliding motility

Plasmodium sporozoites, transmitted to the mammalian host through a mosquito bite, travel to the liver, where they invade hepatocytes, and develop into a form that is then able to infect red blood cells. In spite of the importance of innate immunity in controlling microbial infections, almost nothing is known about its role during the liver stage of a malaria infection. Here, we tested whether synthetic CpG phosphothioate (PS) oligodeoxynucleotides (ODNs), which bind to Toll-like receptor 9 (Tlr9), could have a protective effect on Plasmodium berghei infection in hepatocytes. Surprisingly, CpG PS-ODNs potently impair P. berghei infection in hepatoma cell lines independently of Tlr9 activation. Indeed, not only CpG but also non-CpG PS-ODNs, which do not activate Tlr9, decreased parasite infection. Moreover, the ability of PS-ODNs to impair infection was not due to an effect on the host but rather on the parasite itself. In fact, CpG PS-ODNs, as well as non-CpG PS-ODNs, impair parasite gliding motility. Furthermore, our analysis reveals that PS-ODNs inhibit parasite migration and invasion due to their negative charge, whereas development inside hepatocytes is undisturbed. Altogether, PS-ODNs might represent a new class of prophylactic anti-malaria agents, which hamper hepatocyte entry by Plasmodium sporozoites.

Local cytokine and inflammatory responses to candidate vaginal adjuvants in mice

The current study was undertaken to explore the correlation of adjuvanticity and local inflammatory response elicited in the murine vagina and the draining lymph nodes following local administration of two candidate vaginal adjuvants, Toll like receptor (TLR) 9 agonist CpG ODN, and a non-TLR targeting molecule alpha-galactosylceramide (alpha-GalCer). Using real-time PCR array analysis, we could show that a group of 13 common cytokine genes are activated in the vagina within 24h after vaginal administration of these adjuvants, including Ccl2, Ccl7, Ccl12, Ccl19, Ccl20, Ccl22, Cxcl1, Cxcl5, Il10 and the Th1-inducing molecules Ifng, Cxcl9, Cxcl10 and Cxcl11. A high degree of inflammation in and damage to the epithelium was exclusively observed in the vagina of the CpG ODN treated mice, which was reversed within 48h. These results indicate that there is a group of common genes that correlate with the adjuvanticity of CpG ODN and alpha-GalCer in the vagina, and that alpha-GalCer induces less of local inflammatory reactions in the murine vagina compared to CpG ODN.

Phosphorothioate-modified TLR9 ligands protect cancer cells against TRAIL-induced apoptosis

Hypomethylated CpG oligodeoxynucleotides (CpG ODNs) target TLR9 expressed by immune cells and are currently being evaluated as adjuvants in clinical trials. However, TLR signaling can promote some tumor growth and immune evasion, such as in multiple myeloma (MM). Therefore, deciphering the effects of CpG ODNs on cancer cells will help in preventing these adverse effects and in designing future clinical trials. TLR activation induces multiple signaling pathways, notably NF-kappaB that has been involved in the resistance to TRAIL. Thus, we wondered if CpG ODNs could modulate TRAIL-induced apoptosis in different models of tumors. Here, we show that TLR9+ (NCI-H929, NAN6, KMM1) and TLR9- MM cells (MM1S) were protected by CpG ODNs against recombinant TRAIL-induced apoptosis. By using two fully human, agonist mAbs directed against TRAIL receptors DR4 and DR5 (mapatumumab and lexatumumab, respectively), we show that the protection was restricted to DR5-induced apoptosis. Similar results were observed for two colon cancer (C45 and Colo205) and two breast cancer cell lines (HCC1569 and Cal51). The protection of CpG ODNs was mediated by its nuclease-resistant phosphorothioate backbone independent of TLR9. We next demonstrated by surface plasmon resonance that phosphorothioate-modified CpG ODNs directly bound to either TRAIL or lexatumumab and then decreased their binding to DR5. Finally, NK cell lysis of a DR5-sensitive MM cell line (NCI-H929) through TRAIL was partially inhibited by phosphorothioate-modified CpG ODNs. In conclusion, our results suggest that the phosphorothioate modification of CpG ODNs could dampen the clinical efficacy of CpG ODN-based adjuvants by altering TRAIL/TRAIL receptor interaction.

TLR3 and TLR4 are innate antiviral immune receptors in human microglia: role of IRF3 in modulating antiviral and inflammatory response in the CNS

In the CNS, microglia are the primary targets of HIV infection. In this study, we investigated the effect of activation of the innate antiviral receptors TLR3 and TLR4 on HIV infection of primary human microglia, as well as microglial cell signaling and gene expression. Ligands for both TLR3 and TLR4 potently inhibited HIV replication in microglia through a pathway requiring IRF3. Surprisingly, a remarkably similar pattern of cell signaling and gene expression was observed in TLR3- and TLR4-activated microglia, suggesting a relatively minor role for MyD88 following TLR4 activation in these cells. HIV did not activate IRF3 but rather decreased IRF3 protein, indicating that HIV does not activate TLR3 or RIG-like helicases in microglia. Taken together, these results indicate that activation of TLR3 or TLR4 will elicit antiviral immunity, in addition to inducing proinflammatory responses. We suggest that a balanced expression between inflammatory and innate immune genes might be achieved by IRF3 over-expression.

TLR5 stimulation is sufficient to trigger reactivation of latent HIV-1 provirus in T lymphoid cells and activate virus gene expression in central memory CD4+ T cells

When effector CD4+ T cells carrying integrated HIV-1 proviruses revert back to a resting memory state, the virus can remain silent in those cells for years. Following re-exposure to the nominal antigen or in response to other stimuli (e.g. pro-inflammatory cytokines), these cells can begin to produce virus. Here we demonstrate that TLR5 stimulation induces activation of NF-kappaB and reactivate latent HIV-1 in CD4+ T lymphoid cells. Interestingly, we report also that TLR5 engagement leads to virus gene expression in quiescent central memory CD4+ T cells, a cell population recognized as a major reservoir in infected individuals. This study supports the hypothesis that translocation of microbes that can engage pathogen recognition receptors might play a dominant role in chronic immune activation seen in HIV-1-infected individuals and promote virus replication and dissemination.

Immunomodulatory consequences of ODN CpG-polycation complexes

Immunostimulatory ODN CpGs have extensively been tested as adjuvants and immunotherapeutics and hold a lot of promise for human use. In our studies we took advantage of their negative charge to study their biological activities after being complexed with carbon nanotubes, a novel vector for vaccine delivery and Tat protein of HIV, a target protein for therapeutic or prophylactic intervention. In the case of carbon nanotubes, ODN CpGs were able to form stable complexes based on charge interaction and exert increased immunostimulatory activity in vitro. With regard to the Tat protein, ODN CpGs were shown to bind effectively through the basic domain of the protein representing residues 44-61. Moreover, using surface Plasmon Resonance Technology and an in vitro cellular system, ODN CpGs were shown to inhibit the interaction of Tat protein with the transactivation responsive element, a bulged RNA hairpin structure. However, when ODN CpGs were complexed with Tat they readily increased the apoptotic properties of this protein as studied in CD3-stimulated Jurkat cells. Overall, our findings together with published data support the view that for harnessing the beneficial effects of ODN CpGs a careful consideration has to be given depending on the target intervention.

Protection of neonatal broiler chicks against Salmonella Typhimurium septicemia by DNA containing CpG motifs

Oligodeoxynucleotides (ODN) containing cytosine-phosphodiester-guanine (CpG-ODN) motifs have been shown to stimulate the innate immune system against a variety of bacterial and protozoan infections in a variety of vertebrate species. The objective of this study was to investigate the immunostimulatory effect of CpG-ODN in neonatal broilers against Salmonella Typhimurium septicemia. Day-old broiler chicks, or embryonated eggs that had been incubated for 18 days, received 50 microg of CpG-ODN, 50 microg of non-CpG-ODN, or saline. Four days after exposure to CpG-ODN or day 2 posthatch, 1 x 10(6) or 1 x 10(7) colony-forming units (cfu) of a virulent isolate of Salmonella Typhimurium was inoculated by the subcutaneous route in the neck. Clinical signs, pathology, bacterial isolations from the air sacs, and mortality were observed for 10 days following challenge with Salmonella Typhimurium. The survival rate of birds in groups receiving either non-CpG-ODN or saline following Salmonella Typhimurium infection was 40%-45%. In contrast, birds receiving CpG-ODN had significantly higher survival rate of 80%-85% (P < 0.0001). Bacterial loads and pathology were low in groups treated with CpG-ODN compared to the groups receiving saline or non-CpG-ODN. Colony-forming units of Salmonella Typhimurium in the peripheral blood were significantly lower in birds treated with CpG-ODN compared to the group that received saline. This is the first time that CpG-ODN has been demonstrated to have an immunoprotective effect against an intracellular bacterial infection in neonatal broiler chickens following in ovo delivery.

APOBEC3G upregulation by alpha interferon restricts human immunodeficiency virus type 1 infection in human peripheral plasmacytoid dendritic cells

APOBEC3G (A3G), a member of cytidine deaminase family, has potent anti-human immunodeficiency virus type 1 (HIV-1) activity. It has been demonstrated that alpha interferon (IFN-alpha) can significantly enhance the expression of A3G in human primary resting CD4(+) T-cells, macrophages and primary hepatocytes, subsequently decreasing their viral susceptibility. Plasmacytoid dendritic cells (pDCs) are key effectors in innate host immunity, mediating adaptive immune responses and stimulating IFN-alpha production in reaction to various stimuli. In this report, we demonstrate that IFN-alpha, either exogenously added to- or endogenously secreted by pDCs, can enhance the expression of A3G and its family members such as A3A, A3C and A3F. We have also shown that IFN-alpha can inhibit HIV-1 expression in pDCs. This inhibitory effect could be countered by addition of an A3G-specific short interfering RNA, indicating that IFN-alpha-induced A3G plays a key role in mediating pDCs response to HIV-1. Given the central role played by pDCs in orchestrating the IFN-alpha/A3G intercellular network and intracellular signal pathway, our data indicate that pDCs themselves are also protected by an IFN-alpha/A3G-mediated innate immunity barrier from HIV-1 infection.

Toll-like receptor expression and responsiveness are increased in viraemic HIV-1 infection

OBJECTIVES

Toll-like receptors (TLR) are important in pathogen recognition and may play a role in HIV disease. We evaluated the effect of chronic untreated and treated HIV-1 infection on systemic TLR expression and TLR signalling.

METHODS

Two hundred HIV-infected and uninfected women from a Kenya cohort participated in the studies. TLR1 to TLR10 messenger RNA expression was determined by quantitative reverse transcriptase polymerase chain reaction in peripheral blood mononuclear cells (PBMC). TLR ligand responsiveness was determined in or using ex-vivo PBMC by cytokine production in culture supernatants.

RESULTS

Chronic, untreated HIV-1 infection was significantly associated with increased mRNA expression of TLR6, TLR7, and TLR8 and when analysis was limited to those with advanced disease (CD4 cell count < 200 cells/ml) TLR2, TLR3, and TLR4 were additionally elevated. TLR expression correlated with the plasma HIV-RNA load, which was significant for TLR6 and TLR7. In vitro HIV single-stranded RNA alone could enhance TLR mRNA expression. PBMC of HIV-infected subjects also demonstrated profoundly increased proinflammatory responsiveness to TLR ligands, suggesting sensitization of TLR signalling in HIV. Finally, viral suppression by HAART was associated with a normalization of TLR levels.

CONCLUSION

Together, these data indicate that chronic viraemic HIV-1 is associated with increased TLR expression and responsiveness, which may perpetuate innate immune dysfunction and activation that underlies HIV pathogenesis, and thus reveal potential new targets for therapy.

Therapeutic applications of synthetic CpG oligodeoxynucleotides as TLR9 agonists for immune modulation

Vertebrate toll-like receptors (TLRs) sense invading pathogens by recognizing bacterial and viral structures and, as a result, activate innate and adaptive immune responses. Ten human functional TLRs have been reported so far; three of these (TLR7, 8, and 9) are expressed in intracellular compartments and respond to single-stranded nucleic acids as natural ligands. The pathogen structure selectively recognized by TLR9 in bacterial or viral DNA was identified to be CpG dinucleotides in specific sequence contexts (CpG motifs). Short phosphorothioate-stabilized oligodeoxynucleotides (ODNs) containing such motifs are used as synthetic TLR9 agonists, and different classes of ODN TLR9 agonists have been identified with distinct immune modulatory profiles. The TLR9-mediated activation of the vertebrate immune system suggests using such TLR9 agonists as effective vaccine adjuvants for infectious disease, and for the treatment of cancer and asthma/allergy. Immune activation by CpG ODNs has been demonstrated to be beneficial in animal models as a vaccine adjuvant and for the treatment of a variety of viral, bacterial, and parasitic diseases. Antitumor activity of CpG ODNs has also been established in numerous mouse models. In clinical vaccine trials in healthy human volunteers or in immunocompromised HIV-infected patients, CpG ODNs strongly enhanced vaccination efficiency. Most encouraging results in the treatment of cancers have come from human phase I and II clinical trials using CpG ODNs as a tumor vaccine adjuvant, monotherapy, or in combination with chemotherapy. Therefore, CpG ODNs represent targeted immune modulatory drugs with a broad range of potential applications.

Phosphorothioate-modified oligodeoxynucleotides inhibit human cytomegalovirus replication by blocking virus entry

Studies in animal models have provided evidence that Toll-like receptor 9 (TLR9) agonists, such as synthetic oligodeoxynucleotides (ODNs) that contain immunostimulatory deoxycytidyl-deoxyguanosine (CpG) motifs (CpG ODNs), protect against a wide range of viral pathogens. This antiviral activity has been suggested to be indirect and secondary to CpG-induced cytokines and inflammatory responses triggered through TLR9 activation. However, few studies have addressed the potential of CpG ODNs as direct antiviral agents. Here, we report on the ability of some CpG ODNs to directly suppress, almost completely, human cytomegalovirus (HCMV) replication in both primary fibroblasts and endothelial cells. Murine CMV replication was inhibited as well, whereas no inhibition was observed for herpes simplex virus type 1, adenovirus, or vesicular stomatitis virus. The antiviral activity of these ODNs was significantly reduced when they were added after virus adsorption, indicating that their action may be primarily targeted to the very early phases of the HCMV cycle. In fact, the B-class prototype CpG ODN 2006 effectively prevented the nuclear localization of pp65 and input viral DNA, which suggests that it inhibits HCMV entry. Moreover, a CpG 2006 control, ODN 2137 without CpG motifs, also showed a potent inhibitory activity on the HCMV entry phase, indicating that the anticytomegaloviral activity is independent of the CpG motif. In contrast, a phosphodiester version of CpG 2006 showed reduced antiviral activity, indicating that the inhibitory activity is dependent on the phosphorothioate backbone of the ODN. These results suggest that this yet-unrecognized activity of CpG ODNs may be of interest in the development of novel anticytomegaloviral molecules.

A CpG oligodeoxynucleotide inducing anti-coxsackie B3 virus activity in human peripheral blood mononuclear cells

Coxsackie B3 virus (CVB3) is the most significant pathogen causing myocarditis in humans, and antiviral therapy would be most effective in the early stages of the disease. Here we provide evidence that BW001, a C-type CpG oligodeoxynucleotide, induces anti-CVB3 activity in human peripheral blood mononuclear cells (PBMCs). In parallel, we have demonstrated that BW001 induces human PBMCs to express mRNAs of multiple types of interferon (IFN), including IFN-alpha, IFN-beta, IFN-omega and IFN-gamma, and to express mRNAs of at least 11 subtypes of IFN-alpha. The induced IFNs may contribute to the anti-CVB3 activity. The results suggest that BW001 could be developed into a medication with the potential to treat CVB3 infectious diseases by inducing natural mixed IFNs.

Dual activity of phosphorothioate CpG oligodeoxynucleotides on HIV: reactivation of latent provirus and inhibition of productive infection in human T cells

CpG oligodeoxynucleotides (CpG ODNs) bind to toll-like receptor-9 (TLR-9) and activate immune cells with antigen-presenting activity, including B cells and dendritic cells. Here we show that treatment of the latently human immunodeficiency virus (HIV)-infected T cell line ACH-2 with the CpG ODNs 2006 or 2040 triggers activation of viral gene expression, demonstrating that CpG-signaling activity can also be found in T cells. The CpG ODNs g12AAC and g12GTC had no effect on virus reactivation. In contrast to the stimulating effects on viral gene expression in latently infected cells, CpG ODNs potently suppressed HIV replication in productively infected MT4 T cells or PBLs. Inhibition of virus replication was not related to the CpG motif but similarly occurred with non-CpG phosphorothioate (PTO)-ODNs. Thus, virus inhibition was likely caused by the PTO backbone of the CpG ODNs, probably by interfering with events prior to integration of the viral cDNA into the host genome. The ability of CpG PTO-ODNs to trigger reactivation of latent HIV in combination with their antiviral activity on productive infection makes this substance class an interesting candidate for further test to asses their potential as supplements in HIV therapy.

Polymorphisms in Toll-like receptor 9 influence the clinical course of HIV-1 infection

BACKGROUND

The clinical course of HIV-1 infection is highly variable among individuals, at least in part as a result of genetic polymorphisms in the host. Toll-like receptors (TLRs) have a key role in innate immunity and mutations in the genes encoding these receptors have been associated with increased or decreased susceptibility to infections.

OBJECTIVES

To determine whether single-nucleotide polymorphisms (SNPs) in TLR2-4 and TLR7-9 influenced the natural course of HIV-1 infection.

METHODS

Twenty-eight SNPs in TLRs were analysed in HAART-naive HIV-positive patients from the Swiss HIV Cohort Study. The SNPs were detected using Sequenom technology. Haplotypes were inferred using an expectation-maximization algorithm. The CD4 T cell decline was calculated using a least-squares regression. Patients with a rapid CD4 cell decline, less than the 15th percentile, were defined as rapid progressors. The risk of rapid progression associated with SNPs was estimated using a logistic regression model. Other candidate risk factors included age, sex and risk groups (heterosexual, homosexual and intravenous drug use).

RESULTS

Two SNPs in TLR9 (1635A/G and +1174G/A) in linkage disequilibrium were associated with the rapid progressor phenotype: for 1635A/G, odds ratio (OR), 3.9 [95% confidence interval (CI),1.7-9.2] for GA versus AA and OR, 4.7 (95% CI,1.9-12.0) for GG versus AA (P = 0.0008).

CONCLUSION

Rapid progression of HIV-1 infection was associated with TLR9 polymorphisms. Because of its potential implications for intervention strategies and vaccine developments, additional epidemiological and experimental studies are needed to confirm this association.

Response of nitric oxide production to CpG oligodeoxynucleotides in turkey and chicken peripheral blood monocytes

We evaluated the innate immune response to various synthetic CpG-containing oligodeoxynucleotides (CpG ODNs) by measuring nitric oxide production in the peripheral blood monocytes from turkey poults. The results indicate that the presence of the CpG dinucleotide in ODNs was a prerequisite for activation of turkey monocytes and induction of nitric oxide (NO) synthesis. CpG motifs and sequence structure of the ODNs were also found to influence stimulatory activity greatly. The most potent CpG ODN to induce NO synthesis in turkey monocytes was human-specific CpG ODN M362, followed by CpG ODN 2006 (human), CpG ODN#17 (chicken) and CpG ODN 1826 (mouse). The optimal CpG motif for NO induction was GTCGTT. Phosphorothioate modification of CpG ODNs also significantly increased stimulatory activity. Compared with chicken monocytes, turkey monocytes appeared to be less sensitive to CpG motif variation, whereas chicken monocytes were found to respond more strictly to human-specific CpG ODNs or ODNs that contain GTCGTT motifs.

Therapeutic potential of Toll-like receptor 9 activation

In the decade since the discovery that mouse B cells respond to certain unmethylated CpG dinucleotides in bacterial DNA, a specific receptor for these 'CpG motifs' has been identified, Toll-like receptor 9 (TLR9), and a new approach to immunotherapy has moved into the clinic based on the use of synthetic oligodeoxynucleotides (ODN) as TLR9 agonists. This review highlights the current understanding of the mechanism of action of these CpG ODN, and provides an overview of the preclinical data and early human clinical trial results using these drugs to improve vaccines and treat cancer, infectious disease and allergy/asthma.

TLR7/8 Triggering Exerts Opposing Effects in Acute versus Latent HIV Infection

TLRs trigger innate immunity by recognizing conserved motifs of microorganisms. Recently, ssRNAs from HIV and influenza virus were shown to trigger TLR7 and 8. Thus, we hypothesized that HIV ssRNA, by triggering TLR7/8, affects HIV pathogenesis. Indeed, HIV ssRNA rendered human lymphoid tissue of tonsillar origin or PBMC barely permissive to HIV replication. The synthetic compound R-848, which also triggers TLR7/8, showed similar anti-HIV activity. Loss of R-848's activity in lymphoid tissue depleted of B cells suggested a role for B cells in innate immunity. TLR7/8 triggering appears to exert antiviral effects through soluble factors: conditioned medium reduced HIV replication in indicator cells. Although a number of cytokines and chemokines were increased upon adding R-848 to lymphoid tissue, blocking those cytokines/chemokines (i.e., IFN-alpha receptor, IFN-gamma, MIP-1alpha, -1beta, RANTES, and stromal cell-derived factor-1) did not result in the reversal of R-848's anti-HIV activity. Thus, the nature of this soluble factor(s) remains unknown. Unlike lymphoid tissue acutely infected with HIV, triggering latently infected promonocytic cells induced the release of HIV virions. The anti-HIV effects of triggering TLR7/8 may inhibit rapid killing, while pro-HIV effects may guarantee a certain replication level. Compounds triggering TLR7/8 may be attractive drug candidates to purge latent HIV while preventing new infections.

Anti-HBV effects of CpG oligodeoxynucleotide-activated peripheral blood mononuclear cells from patients with chronic hepatitis B

Unmethylated CpG dinucleotides in bacterial DNA or synthetic oligodeoxynucleotides containing immunostimulatory CpG motifs (CpG ODN) are known as a potent Th1-like immune enhancer in vertebrates. Chronic hepatitis B is the immunocompromising condition. We therefore investigated the effects of CpG ODN on cultured cells from chronic hepatitis B patients and healthy controls. The inhibitory effects of CpG ODN on hepatitis B virus (HBV) were also studied. The secretion of IFN-alpha by CpG ODN-activated peripheral blood mononuclear cells (PBMCs) from chronic hepatitis B patients and healthy controls was significantly increased when compared with PBMCs alone or GpC ODN-stimulated PBMCs. After activation with CpG ODN, the IFN-alpha secretion by chronically HBV-infected patient PBMCs is less than that by healthy control PBMCs. Treatment of HepG2 2.2.15 cells with culture supernatants of PBMCs activated by CpG ODN can significantly suppress the secretion of HBsAg, HBeAg and HBV DNA as compared with that of PBMCs without CpG ODN activation under the same conditions. No inhibitory effect on the replication of HBV was found for CpG ODN treatment alone. Our results indicated that CpG ODN could efficiently enhance the immune response of chronic hepatitis B patients. Moreover, the CpG ODN-activated PBMCs from chronic hepatitis B patients were able to significantly inhibit HBV replication in vitro, suggesting that CpG ODN may be a potential immunoregulator against HBV infection in the future.

Effective treatment of retrovirus-induced suppression of antibody responses with CpG oligodeoxynucleotides

Most retroviruses induce severe immunosuppression during acute infection. We have used the Friend retrovirus mouse model to demonstrate that immunostimulatory B-type CpG oligodeoxynucleotides (ODN) have a protective effect against retrovirus-induced suppression of antibody responses to potent B-cell antigens. CD8+ T cells were critical for effective treatment with CpG-ODN, since in vivo depletion of these cells from treated mice impaired protection from retrovirus-induced immunosuppression. Protection also required IFN-gamma, as neutralization of this cytokine abolished the therapeutic effect of CpG-ODN. These findings may have implications for the treatment of immunosuppressive virus infections.

Increased expression of TLR3 in lymph nodes during simian immunodeficiency virus infection: implications for inflammation and immunodeficiency

As pattern recognition receptors, TLRs signal and induce expression of multiple host defense genes including proinflammatory cytokines and chemokines. To investigate the mechanisms of up-regulation of proinflammatory cytokines and chemokines during SIV infection in rhesus macaques, we measured the relative levels of expression of TLRs 1-10 in lymphoid tissues during different stages of SIV infection. By real-time RT-PCR, TLR3 was determined to be up-regulated in macaque lymph nodes (LN) throughout the course of infection, whereas TLR9 was down-regulated during early stages of infection. CXCL9/Mig, CXCL10/IP-10, IFN-gamma, and IFN-alpha mRNAs were also increased during acute SIV infection and AIDS. Treatment of macaque spleen and LN cells with TLR3 and TLR9 ligands led to the induction of these same genes. TLR3 stimulation had disparate effects on viral transcription and viral replication, because poly(I:C), a model TLR3 ligand, stimulated the viral promoter but potently inhibited SIV replication in primary cultures of macaque spleen and LN cells. These findings identify roles for TLR3 inflammation in lymphoid tissues and in the immunopathogenesis of HIV-1/SIV, and suggest that TLR3 ligands could potentially be used to flush out latently infected cells that persist during antiretroviral therapies.

Uncoupled anti-HIV and immune-enhancing effects when combining IFN-alpha and IL-7

Cytokine-based therapies have been examined for purging viral reservoirs and immunomodulation in HIV infection. However, single cytokines did not result in either HIV eradication or an efficient HIV-specific immune response. We hypothesize that cytokines with distinct biologic effects need to be combined for immunotherapy of HIV infection. In this study, we investigated the anti-HIV activity and immune-enhancing effects of the combination of IFN-alpha and IL-7. In human lymphocyte aggregate cultures infected ex vivo with the X4 HIV strain NL4-3, IFN-alpha/IL-7 potently inhibited HIV replication and preserved CD4(+) T cells, probably by up-regulating Bcl-2. IFN-alpha/IL-7 also strongly inhibited R5 HIV replication. Furthermore, in allogeneic MLRs, IFN-alpha/IL-7 increased T cell proliferation and IFN-gamma production. IFN-alpha alone also had strong anti-HIV activity, but neither preserved CD4(+) T cells nor increased T cell responses in MLRs. IL-7 alone maintained T cells and enhanced T cell activation in MLRs, but only moderately inhibited or increased HIV replication. Thus, coadministration of IFN-alpha/IL-7 combines the potent anti-HIV activity of IFN-alpha with the beneficial effects of IL-7 on T cell survival and function. We speculate that IFN-alpha will block viral replication, activate APCs, and up-regulate MHC molecules, thus allowing IL-7 to display its effects for generating an efficient immune response. In this scenario, the known reactivation of latent HIV by IL-7 may be advantageous.