Association of single-nucleotide polymorphisms in TLR7 (Gln11Leu) and TLR9 (1635A/G) with a higher CD4T cell count during HIV infection

Meta-analysis of the association between toll-like receptor gene polymorphisms and hepatitis C virus infection

Objective

The objective of this study is to investigate the association between toll-like receptor (TLR) 3/7 gene polymorphisms and the infection by hepatitis C virus (HCV).

Methods

PubMed, Embase, Web of Science, Scopus, CNKI, Wanfang Data, and SinoMed were searched to identify studies focusing on the association between the TLR3 rs3775290 or the TLR7 rs179008 single nucleotide polymorphisms (SNPs) and the HCV infection. All the related articles were collected from the inception of each database to 15 January 2023. Our meta-analysis was conducted using the allelic model, the dominant model, and the recessive model. Outcomes were presented by odds ratio (ORs) and 95% confidence interval (95%CI). The heterogeneity across studies was assessed by the I2 test. A subgroup analysis was performed to explore the source of heterogeneity. Funnel plots were drawn to assess the risk of publication bias. Review Manager 5.4 was used for statistical analysis.

Results

Ten articles were finally included, among which six studies were analyzed for rs3775290 and five studies were analyzed for rs179008. Studies relating to rs3775290 included 801 patients and 1,045 controls, whereas studies relating to rs179008 included 924 patients and 784 controls. The results of the meta-analysis showed that there is no significant association between rs3775290 gene polymorphism and HCV infection (T vs. C: OR = 1.12, 95%CI 0.97-1.30; TT+CT vs. CC: OR = 1.20, 95%CI 0.73-1.96; TT vs. CT+CC: OR = 1.13, 95%CI 0.68-1.89). The recessive model showed that rs179008-T allele homozygotes had an 89% increased risk of infection by HCV compared with rs179008-A allele carriers (TT vs. AT+AA: OR = 1.89, 95%CI 1.13-3.16). The results of the subgroup analysis demonstrated that the characteristics of the control population may serve as an important source of heterogeneity. In the African populations, individuals with homozygous rs179008-T alleles had a higher risk of infection by HCV than rs179008-A allele carriers (OR = 2.14, 95%CI 1.18-3.87). We did not find that this difference existed in the European populations (OR = 1.24, 95%CI 0.43-3.56).

Conclusion

There is no significant association between rs3775290 single nucleotide polymorphism and the infection by HCV. Individuals with homozygous rs179008-T alleles have a higher risk of an infection by HCV than rs179008-A allele carriers, which is statistically significant in the African populations.

Role of TLRs in HIV-1 Infection and Potential of TLR Agonists in HIV-1 Vaccine Development and Treatment Strategies

Toll-like receptors (TLRs), as a family of pattern recognition receptors, play an important role in the recognition of HIV-1 molecular structures by various cells of the innate immune system, but also provide a functional association with subsequent mechanisms of adaptive immunity. TLR7 and TLR8 play a particularly important role in the innate immune response to RNA viruses due to their ability to recognise GU-rich single-stranded RNA molecules and subsequently activate intracellular signalling pathways resulting in expression of genes coding for various biological response modifiers (interferons, proinflammatory cytokines, chemokines). The aim of this review is to summarise the most recent knowledge on the role of TLRs in the innate immune response to HIV-1 and the role of TLR gene polymorphisms in the biology and in the clinical aspects of HIV infections. In addition, the role of TLR agonists as latency reversing agents in research to treat HIV infections and as immunomodulators in HIV vaccine research will be discussed.

TLR9 2848 G/A Gene Polymorphism in HCV+, HIV+, and HCV+/HIV+ Individuals

Background: Host genetic factors have a major impact on susceptibility to infections. Toll-like receptors (TLRs) and their polymorphisms affect infectious diseases once they are directly involved in immune responses. The 2848 G/A variant (rs352140) of the TLR9 gene is associated with increased TLR9 expression. However, the impact of rs352140 on HIV+, HCV+, and HCV+/HIV+ individuals is still debated. Materials and Methods: This study investigated the 2848 G/A polymorphism in hepatitis C virus (HCV) infection, human immunodeficiency virus (HIV) infection, and HCV/HIV coinfection in a large sample of Brazilians (n = 1182). Groups were compared without considering stratification by ethnicity and subsequently stratifying individuals into groups of whites and nonwhites. Results: Considering nonwhite individuals, a significant difference between the HIV+/HCV+ group and controls was observed (p = 0.023; GG genotype as a protective factor). In addition, significant allele differences were observed between the HCV+ group and controls (p = 0.042), between the HIV+/HCV+ group and controls (p = 0.011), and between the HIV+/HCV+ group and HIV+ individuals (p = 0.047). However, all significant results are lost if adjustment by multiple comparisons is applied (p > 0.05). Conclusions: Although our initial results indicate a potential influence of rs352140 on altered host susceptibility to viral infections, no statistical influence of polymorphism on protection from/susceptibility to infections was observed in Brazilians if adjustment by multiple comparisons is considered.

The TLR9 2848C/T Polymorphism Is Associated with the CMV DNAemia among HIV/CMV Co-Infected Patients

Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns and are essential components of the host’s innate immune response. The aim of this study was to determine the TLR9 genotype frequency and investigate the association between TLR9 polymorphisms and cytomegalovirus (CMV) DNAemia in human immunodeficiency virus (HIV)/CMV co-infected patients. A total of 205 HIV/CMV co-infected adults were screened for the presence of the four TLR9 polymorphisms (−1237T/C, −1486T/C, 1174G/A, and 2848C/T) by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Mutation presented in at least one allele of the TLR9 2848C/T single nucleotide polymorphism (SNP) was associated with the occurrence of CMV DNAemia among HIV-infected patients with CMV co-infection (p = 0.004). The level of CMV DNA was higher in patients who were homozygous recessive or heterozygous for the 2848C/T polymorphism compared with those who had a wild-type genotype for this polymorphism (p = 0.005). Mutation detected in at least one allele of this SNP was also associated with a lower interferon type β (IFN-β) concentration (p = 0.048), while no relationships between TLR9 −1237T/C, −1486T/C, and 1174G/A SNPs and CMV DNAemia were observed. Our findings suggest that the mutation present in at least one allele of the TLR9 2848C/T SNP may be associated with the active CMV infection in HIV/CMV co-infected subjects.

Single Nucleotide Polymorphisms in Genes Encoding Toll-Like Receptors 7 and 8 and Their Association with Proviral Load of SRLVs in Goats of Polish Carpathian Breed

Toll-like receptors (TLRs) 7 and 8 are important in single-stranded viral RNA recognition, so genetic variation of these genes may play a role in SRLVs infection and disease progression. Present study aimed to identify SNPs in genes encoding TLR7 and TLR8 in goats of Carpathian breed and analyze their association with the SRLVs provirus concentration as index of disease progression. A total of 14 SNPs were detected, 6 SNPs in the TLR7 gene locus and 8 SNPs in the TLR8 gene. Nine of the 14 identified polymorphisms, 4 in the TLR7 gene and 5 in TLR8 gene, were significantly associated with the SRLVs proviral concentration. These SNPs were located in 3'UTR, 5'UTR and intron sequences as well as in the coding sequences, but they led to silent changes. Homozygous genotypes of three TLR7 SNPs (synonymous variant 1:50703293, 3'UTR variant 1:50701297 and 5'UTR variant 1:50718645) were observed in goats with lower provirus copy number as well as in seronegative animals. The results obtained in this study suggest that SNPs of TLR7/TLR8 genes may induce differential innate immune response towards SRLVs affecting proviral concentration and thereby disease pathogenesis and progression. These findings support a role for genetic variations of TLR7 and TLR8 in SRLVs infection and warrants further studies on the effect of TLR7/TLR8 polymorphisms on SRLVs infection in different populations.

Activation of Toll-like receptor 7 provides cardioprotection in septic cardiomyopathy-induced systolic dysfunction

BACKGROUND

As a pattern recognition receptor, Toll-like receptor 7 (TLR7) widely presented in the endosomal membrane of various cells. However, the precise role and mechanism of TLR7 in septic cardiomyopathy remain unknown. This study aims to determine the role of TLR7 in cardiac dysfunction during sepsis and explore the mechanism of TLR7 in septic cardiomyopathy.

METHODS

We generated a mouse model of septic cardiomyopathy by challenging with lipopolysaccharide (LPS). TLR7-knockout (TLR7-/- ), wild-type (WT) mice, cardiac-specific TLR7-transgenic (cTG-TLR7) overexpression, and littermates WT (LWT) mice were subjected to septic model. Additionally, to verify the role and mechanism of TLR7 in vitro, we transfected neonatal rat ventricular myocytes (NRVMs) with Ad-TLR7 and TLR7 siRNA before LPS administration. The effects of TLR7 were assessed by Ca2+ imaging, western blotting, immunostaining, and quantitative real-time polymerase chain reaction (qPCR).

RESULTS

We found that TLR7 knockout markedly exacerbated sepsis-induced systolic dysfunction. Moreover, cardiomyocytes isolated from TLR7-/- mice displayed weaker Ca2+ handling than that in WT mice in response to LPS. Conversely, TLR7 overexpression alleviated LPS-induced systolic dysfunction, and loxoribine (TLR7-specific agonist) improved LPS-induced cardiac dysfunction. Mechanistically, these optimized effects were associated with enhanced the adenosine (cAMP)-protein kinase A (PKA) pathway, which upregulated phosphorylate-phospholamban (p-PLN) (Ser16) and promoted sarco/endoplasmic reticulum Ca2+ ATPase (Serca) and Ryanodine Receptor 2 (RyR2) expression in the sarcoplasmic reticulum (SR), and ultimately restored Ca2+ handling in response to sepsis. While improved Ca2+ handling was abrogated after H89 (a specific PKA inhibitor) pretreatment in cardiomyocytes isolated from cTG-TLR7 mice. Consistently, TLR7 overexpression improved LPS-induced Ca2+ -handling decrement in NRVMs. Nevertheless, TLR7 knockdown showed a deteriorative phenotype.

CONCLUSIONS

Our data demonstrated that activation of TLR7 protected against sepsis-induced cardiac dysfunction through promoting cAMP-PKA-PLN pathway, and we revealed that TLR7 might be a novel therapeutic target to block the septic cardiomyopathy and support systolic function during sepsis.

Association of toll-like receptor polymorphisms with acquisition of HIV infection and clinical findings: A protocol for systematic review and meta-analysis

BACKGROUND

To find the relationship between toll-like receptor (TLR) gene variants and human immunodeficiency virus (HIV) infection and clinical findings, which could inform clinical decisions and vaccination strategies.

METHOD

Four databases were searched for articles that were published on or before Jul.1, 2020. Review Manager 5.3 software was applied to perform meta-analysis to explore.

RESULTS

A total of 10 studies involving 20 genes, 3697 cases, and 6498 controls were included in this systematic review. TLR2 -196 to -174 Ins/Del (odds ratio [OR] = 1.562; P = .002), TLR4 rs4986790 (OR = 2.05; P = .002), TLR3 rs3775291 (OR = 0.25; P = .03), TLR7 rs179008 (P = .002), TLR7 rs2074109 (OR = 0.27, P = .019) were found associated with HIV infection. TLR2 -196 to -174, TLR4 rs4986790, TLR7 rs179008, TLR8 rs3764880, TLR9 rs352140 were found associated with clinical findings of HIV infection. We identified 5 case-control studies in meta-analysis, involving 695 cases and 729 controls on TLR7 rs179008 polymorphism, totaling 652 cases and 614 controls on TLR9 rs352140 polymorphism. In meta-analysis, we employed various genetic models. The T allele of TLR7 rs179008 was conferred the risk of HIV infection (T vs A: OR = 1.25, PA = .02). An increased risk of HIV infection was found for individuals with the TLR9 rs352140 GG genotype (GG vs AA: OR = 1.50, PA = .04).

CONCLUSIONS

The systematic review indicated that TLR7 rs179008 T allele provides risk effects for HIV infection. TLR9 rs352140 GG genotype may associate with HIV infection.

The Role of Toll-Like Receptors in Retroviral Infection

Toll-like receptors (TLRs) are key pathogen sensing receptors that respond to diverse microbial ligands, and trigger both innate and adaptive immune responses to infection. Since their discovery, a growing body of evidence has pointed to an important role for TLRs in retroviral infection and pathogenesis. These data suggest that multiple TLRs contribute to the anti-retroviral response, and that TLR engagement by retroviruses can have complex and divergent outcomes for infection. Despite this progress, numerous questions remain about the role of TLRs in retroviral infection. In this review, I summarize existing evidence for TLR-retrovirus interactions and the functional roles these receptors play in immunity and pathogenesis, with particular focus on human immunodeficiency virus (HIV).

Effects of TLR7 Polymorphisms on the Susceptibility and Progression of HIV-1 Infection in Chinese MSM Population

Toll-like receptor (TLR) 7 plays a key role in innate and adaptive immunity for HIV-1 infection. We evaluated the effect of TLR7 polymorphisms on disease susceptibility and progression of HIV-1 infection in Chinese MSM (men who have sex with men). Blood samples were taken from 270 patients with laboratory confirmed HIV infection, 196 male controls were tested, and three TLR7 intronic polymorphisms (rs179010-C > T, X:12884766; rs2074109-T > C, X:12885330; and rs179009-A > G, X:12885361) were analyzed by PCR-based sequencing. The frequency of TLR7 rs179010 T allele was significantly lower in MSM patients than in controls (P = 0.039). The haplotype TTA was associated with a decreased susceptibility to HIV-1 infection (P = 0.013), especially to acute HIV-1 infection (AHI) (P = 0.002), but not to chronic HIV-1 infection (CHI). Furthermore, the haplotype TTA is linked to slow disease progression in AHI patients (P = 0.002) and a lower viral load (P = 0.042). In contrast, TLR7 rs179009 allele A contributed to a higher set point in AHI patients with rapid progression, and the frequency of rs179009 minor allele G was over-presented in CHI patients. This finding supports a role for genetic variations of TLR7 in susceptibility and disease progression of an HIV-1 infection in Chinese Han population and warrants further studies on the effect of TLR7 polymorphisms on HIV-1 infection in different populations.

Brief Report: Toll-like Receptor 9-1635A/G Polymorphism Is Associated With HIV-1 Rebound After Four Weeks of Interruption of Antiretroviral Therapy

OBJECTIVES

This study aims to analyze the association of the presence of common polymorphisms [single nucleotide polymorphisms (SNPs)] on Toll-like receptors (TLRs), such as TLR9-1635A/G, TLR2-1892A/C, TLR2-2258G/A, TLR4-899A/G, and TLR4-1196C/T, with the viral rebound after stopping antiretroviral treatment (ART). CCR5-Δ32 deletion and HLA-A/HLA-B alleles were also analyzed.

DESIGN

Interruption of ART may be required to investigate the outcome of strategies aimed to achieve drug-free HIV remission or cure. However, interruption of ART is currently not indicated. This was a retrospective longitudinal study that included 57 long-term suppressed HIV-1-infected individuals.

METHODS

TLR SNPs were detected by real-time polymerase chain reaction (PCR). CCR5-Δ32 was analyzed by conventional PCR and HLA-A and HLA-B alleles by PCR-SSOP Luminex.

RESULTS

HIV-1 RNA rebound at week 4 after treatment interruption positively correlated with pre-ART HIV-1 load (P = 0.025). The TLR9-1635AA genotype was independently associated with a higher HIV-1 rebound compared with those with AG + GG genotype (multivariate stepwise regression analysis, P = 0.004). Women had lower HIV-1 RNA load both at rebound and during the 72 weeks of follow-up compared with men (P < 0.05 at all time-points), whereas CD4 nadir and CD4 count set-point were similar according to sex. The pre-ART viral load was independently associated with the viral set-point (P = 0.001), whereas the presence of the HLA-A01 allele (P = 0.027) and the CD4 nadir (P = 0.001) were associated with the CD4 count set-point.

CONCLUSIONS

The association of the TLR9-1635AA genotype with a higher HIV-1 rebound suggests that this SNP may affect the results from strategies requiring interruption of ART aimed to cure HIV-1 infection.

An assessment of toll-like receptor 7 and 8 gene polymorphisms with susceptibility to HIV-1 infection, AIDS development and response to antiretroviral therapy

Toll-like receptors (TLRs) play an important role in activating the innate immune response, inducing inflammation and initiating the adaptive immune response. In this study, we assess the influence of TLR7 and TLR8 gene polymorphisms on HIV-1 susceptibility, AIDS development, and treatment outcomes. The TLR7 and TLR8 single nucleotide polymorphisms (SNPs) were genotyped through real-time PCR in 222 patients living with HIV-1 and 141 healthy controls. Frequencies of the TLR7-IVS2-151 G/A and TLR7-IVS1 + 1817 G/T genotypes and alleles were not significantly increased in patients with HIV-1 infection compared to healthy controls both in males and females. Whereas, males carrying TLR8 Met allele were twice susceptible to HIV-1 infection compared to subjects with A allele (OR = 2.04, 95 % CI 1.10-3.76; p = 0.021). Interestingly, for TLR8-129 G/C, both males and females carrying G allele and GG genotype, respectively were significantly associated with HIV-1 infection (p < 0.0001). Moreover, the TLR7 IVS1 + 1817 G/T and the TLR8 rs3764880 were associated with protection to progress the AIDS stage in male and female, respectively (p < 0.05). Males carrying TLR7 IVS2-151-A allele showed a significant increased level of HIV-1 viral load pre-treatment, in comparison with individuals carrying the G allele (p-value = 0.036). Additionally, males carrying TLR8 Met allele showed statistically higher HIV viral load at baseline (p-value = 0.04) and after treatment (p-value = 0.013). Regarding CD4 + T cell counts, no significant association was found with TLR7 and TLR8 SNPs before and after antiretroviral treatment. This data demonstrates that TLR8 polymorphisms could affect HIV-1 infection. Moreover, an association between TLR7 IVS2-151-A and TLR8 Met alleles and plasma HIV viral load level was found.

TLR7 Polymorphism (rs179008 and rs179009) in HIV-Infected Individual Naïve to ART

Toll-like receptors (TLRs) play an important role in the innate immune response to HIV infection. Single nucleotide polymorphism (SNP) in TLR7 (Gln11Leu) gene has been associated with a rapid decline of CD4T cell count. Hence, we assessed the TLR7 (rs179008, Gln11Leu (A/T) and rs179009, IVS2-151 (A/G)) polymorphism in 150 HIV-infected individuals naïve to ART and 158 healthy controls. The genotyping of TLR7 Gln11Leu (A/T) and IVS2-151 (A/G) polymorphisms was done using the PCR-RFLP method. In univariate analysis, none of the genotype and haplotype of TLR7 Gln11Leu (A/T) and IVS2-151 (A/G) polymorphism differed significantly between HIV-infected individuals and healthy controls. The occurrence of TLR7 rs179009AG genotype in the codominant model and rs179009 AG-GG genotype in the dominant model was significantly reduced in HIV-infected individuals as compared to healthy controls (18.0% vs. 29.1%, OR = 0.42, P = 0.016; 26.7% vs. 36.7%, OR = 0.52, P = 0.016). TLR7 rs179009AG genotype was significantly underrepresented in the intermediate HIV disease stage compared with healthy controls (OR = 0.03, P = 0.04). TLR7 rs179009AG genotype expressed higher in tobacco-consuming HIV-infected individuals compared with nonusers (OR = 1.71, P = 0.47). In conclusion, rs179009 AG-GG and AG genotypes were found reduced in HIV-infected individuals as compared to healthy controls; their higher prevalence in health individuals clearly support that they are associated with reduced risk of acquisition of HIV-1 infection.

HSV-2 Infection of Human Genital Epithelial Cells Upregulates TLR9 Expression Through the SP1/JNK Signaling Pathway

It is known that herpes simplex virus type 2 (HSV-2) triggers the activation of Toll-like receptor (TLR) 9 signaling pathway and the consequent production of antiviral cytokines in dendritic cells. However, the impact of HSV-2 infection on TLR9 expression and signaling in genital epithelial cells, the primary HSV-2 targets, has yet to be determined. In the current study, by using both human genital epithelial cell lines and primary genital epithelial cells as models, we found that HSV-2 infection enhances TLR9 expression at both mRNA and protein levels. Such enhancement is virus replication-dependent and CpG-independent, while the HSV-2-mediated upregulation of TLR9 does not activate TLR9 signaling pathway. Mechanistically, a SP1 binding site on TLR9 promoter appears to be essential for HSV-2-induced TLR9 transactivation. Upon HSV-2 infection, SP1 translocates from the cytoplasm to the nucleus, and consequently binds to TLR9 promoter. By using specific inhibitors, the JNK signaling pathway is shown to be involved in the HSV-2-induced TLR9 transactivation, while HSV-2 infection increases the phosphorylation but not the total level of JNK. In agreement, antagonism of JNK signaling pathway inhibits the HSV-2-induced SP1 nuclear translocation. Taken together, our study demonstrates that HSV-2 infection of human genital epithelial cells promotes TLR9 expression through SP1/JNK signaling pathway. Findings in this study provide insights into HSV-2-host interactions and potential targets for immune intervention.

Polymorphisms in Toll-Like Receptors (TLRs)-7 and 9 Genes in Indian Population with Progressive and Nonprogressive HIV-1 Infection

The polymorphisms in Toll-like receptor (TLR) 7 and 9 genes are shown to influence HIV-1 infection. We studied HIV-1-infected Indian individuals for presence and association of TLR7 and 9 gene polymorphism with different disease outcomes. Genomic DNA from 65 HIV-infected individuals (35 long-term nonprogressors and 30 progressors) and 89 uninfected healthy donors was isolated, amplified, and sequenced for the reported polymorphisms in TLR7 [Gln11Leu (A/T); rs179008] and TLR9 (1635A/G; rs352140) genes. Of these, only the reported TLR9 single-nucleotide polymorphism [SNP; p = .017, odds ratio (OR) = 0.20] and its allele A frequency (p = .038, OR = 0.41) were found to be associated with slow disease progression. Of the new SNPs observed (three TLR7 and two TLR9), the TLR7 rs2074109 G allele showed less likely association with HIV-1 acquisition (p = .019, OR = 0.27). These findings indicate that TLR7 SNP (rs2074109) could be one of the factors for predisposition to HIV-1 and TLR9 1635A/G genotype and allele might have a role in HIV-1 disease progression in Indian population.

TLR9 polymorphism correlates with immune activation, CD4 decline and plasma IP10 levels in HIV patients

Background

The mechanism behind HIV mediated immune activation remains debated, although the role of virus replication in this process is increasingly evident. Toll like Receptor 9 (TLR9) has been implicated in HIV mediated immune activation via sensing of viral CpG DNA. Polymorphisms in the TLR9 gene and promoter region including TLR9 1635A/G and 1486C/T have been found to be associated with multiple infectious diseases and cancers.

Methods

In the current study, we looked at the correlation of TLR9 polymorphisms 1635A/G and 1486C/T with key hallmarks of HIV disease in a cohort of 50 HIV infected patients. We analyzed CD4 counts, T cell immune activation characterized by upregulation of CD38 and HLA-DR and upregulation of plasma biomarkers of inflammation like LPS, sCD14, IL-6 and IP10 in the HIV patient cohort and compared it to healthy controls.

Results

We found that TLR9 1635AA genotype was associated with lower CD4 counts and significantly higher immune activation in both CD4+ and CD8+ T cells. Analysis of HIV associated plasma biomarkers including LPS, sCD14, IL-6 and IP10 revealed a strong correlation between IP10 and immune activation. Interestingly, IP10 levels were also found to be higher in HIV patients with the 1635AA genotype. Furthermore, the TLR9 1486C/T polymorphism that is in linkage disequilibrium with 1635A/G was weakly associated with lower CD4 counts, higher CD8 immune activation and higher IP10 levels.

Conclusions

As TLR9 stimulation is known to induce IP10 production by dendritic cells, our findings provide new insights into HIV mediated immune activation and CD4 loss. TLR9 stimulation by viral CpG DNA may be important to HIV immunopathogenesis and the TLR9 polymorphisms 1635A/G and 1486C/T may be associated with disease progression.

TLR7 polymorphism, sex and chronic HBV infection influence plasmacytoid DC maturation by TLR7 ligands

TLR7 agonists are of high interest for the treatment of cancer, auto-immunity and chronic viral infections. They are known to activate plasmacytoid dendritic cells (pDCs) to produce high amounts of Type I Interferon (IFN) and to facilitate T and B cell responses, the latter with the help of maturation markers such as CD40, CD80 and CD86. The TLR7 single nucleotide polymorphism (SNP) rs179008 (GLn11Leu), sex and chronic viral infection have all been reported to influence pDC IFN production. It is unknown, however, whether these factors also influence pDC phenotypic maturation and thereby IFN-independent pDC functions. Furthermore, it is unclear whether SNP rs179008 influences HBV susceptibility and/or clearance. Here we investigated whether the SNP rs179008, sex and HBV infection affected phenotypic maturation of pDCs from 38 healthy individuals and 28 chronic HBV patients. In addition, we assessed SNP prevalence in a large cohort of healthy individuals (n = 231) and chronic HBV patients (n = 1054). Consistent with previous reports, the rs179008 variant allele was largely absent in Asians and more prevalent in Caucasians. Among Caucasians, the SNP was equally prevalent in healthy and chronically infected males. The SNP was, however, significantly more prevalent in healthy females than in those with chronic HBV infection (42 versus 28%), suggesting that in females it may offer protection from chronic infection. Ex vivo experiments demonstrated that induction of the co-stimulatory molecules CD40 and CD86 by TLR7 ligands, but not TLR9 ligands, was augmented in pDCs from healthy SNP-carrying females. Furthermore, CD80 and CD86 upregulation was more pronounced in females independent of the SNP. Lastly, our data suggested that chronic HBV infection impairs pDC maturation. These findings provide insight into factors determining TLR7 responses, which is important for further clinical development of TLR7-based therapies.

Viruses Seen by Our Cells: The Role of Viral RNA Sensors

The role of the innate immune response in detecting RNA viruses is crucial for the establishment of proper inflammatory and antiviral responses. Different receptors, known as pattern recognition receptors (PRRs), are present in the cytoplasm, endosomes, and on the cellular surface. These receptors have the capacity to sense the presence of viral nucleic acids as pathogen-associated molecular patterns (PAMPs). This recognition leads to the induction of type 1 interferons (IFNs) as well as inflammatory cytokines and chemokines. In this review, we provide an overview of the significant involvement of cellular RNA helicases and Toll-like receptors (TLRs) 3, 7, and 8 in antiviral immune defenses.

Type I interferon and HIV: Subtle balance between antiviral activity, immunopathogenesis and the microbiome

Type I interferon (IFN) response initially limits HIV-1 spread and may delay disease progression by stimulating several immune system components. Nonetheless, persistent exposure to type I IFN in the chronic phase of HIV-1 infection is associated with desensitization and/or detrimental immune activation, thereby hindering immune recovery and fostering viral persistence. This review provides a basis for understanding the complexity and function of IFN pleiotropic activity in HIV-1 infection. In particular, the dichotomous role of the IFN response in HIV-1 immunopathogenesis will be discussed, highlighting recent advances in the dynamic modulation of IFN production in acute versus chronic infection, expression signatures of IFN subtypes, and viral and host factors affecting the magnitude of IFN response during HIV-1 infection. Lastly, the review gives a forward-looking perspective on the interplay between microbiome compositions and IFN response.

Toll-like receptor 9 polymorphism is associated with increased Epstein-Barr virus and Cytomegalovirus acquisition in HIV-exposed infants

: Polymorphisms in the Toll-like receptor 9 1635 locus have been associated with HIV-1 acquisition and progression. Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) acquisition were compared between Kenyan HIV-exposed infants by 1635 genotype. Having one or more copies of the 1635A allele was associated with increased CMV acquisition in HIV-infected infants (42 vs. 11%, P = 0.03) and increased risk of EBV acquisition in HIV-exposed uninfected infants (hazard ratio = 4.2, P = 0.02) compared with 1635GG. In addition, 1635A was associated with 0.4 log10 copies/ml lower median EBV levels in HIV-infected infants (P = 0.03). These data suggest a potentially important role for this locus in primary herpesvirus infection.

Toll like receptor7 polymorphisms in relation to disease susceptibility and progression in Chinese patients with chronic HBV infection

Toll-like receptors (TLRs) play a key role in innate and adaptive immunity, protecting the host from viral pathogens. We studied the effect of TLR7 polymorphisms on disease susceptibility and progression of chronic hepatitis B (CHB) infection in Chinese adults. Blood samples were taken from 612 patients with confirmed CHB, hepatitis B virus (HBV)-related liver cirrhosis (LC) or hepatocellular carcinoma (HCC) and 293 controls. TLR7 polymorphisms (rs179010-C > T, rs2074109-T > C, and rs179009-A > G) were analyzed by PCR-based sequencing. A significantly higher frequency of TLR7 rs179010 C allele was found in male CHB patients than in controls (74.8% vs 59.5%, P = 0.002). The frequency of rs179009 G allele was markedly increased with disease progression when male patients with CHB, LC and HCC were compared (P = 0.012). The haplotype CTA was significantly associated with an increased susceptibility to CHB among male patients (P = 0.000). Frequency of the haplotype CTG was higher in male patients with HCC than CHB (P = 0.005). No such differences in these allele frequencies were found between female patients and controls. Our results indicated that TLR7 polymorphisms play an important role in disease susceptibility and the progression of CHB infections in Chinese adults, and may partly explain the high incidence of HBV related diseases in Chinese men.

Endosomal toll-like receptor gene polymorphisms and susceptibility to HIV and HCV co-infection - Differential influence in individuals with distinct ethnic background

The genetic background of human populations can influence the susceptibility and outcome of infection diseases. Toll-like receptors (TLRs) have been previously associated with susceptibility to human immunodeficiency virus (HIV) infection, disease progression and hepatitis C, virus (HCV) co-infection in different populations, although mostly in Europeans. In this study, we investigated the genetic role of endosomal TLRs on susceptibility to HIV infection and HCV co-infection through the analysis of TLR7 rs179008, TLR8 rs3764880, TLR9 rs5743836 and TLR9 rs352140 polymorphisms in 789 Brazilian individuals (374 HIV+ and 415 HIV-), taking into account their ethnic background. Amongst the 357 HIV+ individuals with available data concerning HCV infection, 98 were positive. In European descendants, the TLR9 rs5743836 C carriers displayed a higher susceptibility to HIV infection [dominant, Odds Ratio (OR)=1.53; 95% CI: 1.05-2.23; P=0.027]. In African descendants, TLR9 rs5743836 CT genotype was associated with protection to HIV infection (codominant, OR=0.51; 95% CI: 0.30-0.87; P=0.013). Also, the TLR9 rs352140 AA variant genotype was associated with susceptibility to HIV+/HCV+ co-infection in African descendants (recessive, OR=2.92; 95% CI: 1.22-6.98, P=0.016). These results are discussed in the context of the different ethnic background of the studied individuals highlighting the influence of this genetic/ethnic background on the susceptibility to HIV infection and HIV/HCV co-infection in Brazilian individuals.

TLR7 rs2897827 Polymorphism Affects TLR7 Gene mRNA Expression and Serum Apolipoprotein A1 Level of Ischemic Stroke Patients in a Chinese Han Population

Stroke is a multi-factorial disorder that has become the leading cause of death and disability worldwide. Previous studies reported that TLR7 mRNA expression is associated with poor outcome of ischemic stroke (IS). This study aimed to assess whether TLR7 mRNA expression affects IS occurrence, as well as the association of TLR7 rs2897827 with susceptibility to IS and TLR7 mRNA expression and serum apolipoprotein and lipid levels in a Chinese Han population. A total of 816 stroke patients and 816 healthy controls were included in this study. mRNA expression was determined by quantitative real-time PCR. The Sequenom MassARRAY iPLEX platform was used to genotype the TLR7 rs2897827 polymorphism. TLR7 mRNA expression of the IS cases was statistically significantly higher than that of the controls in the male or female group (male, P = 0.014; female, P = 0.025). In the male IS cases, TLR7 mRNA expression of the T allele carriers was statistically significantly higher than that of the C allele carriers (P = 0.018). However, a significant difference was not observed in the female cases (P = 0.545). In either the male or female group, the distribution of genotype or allele had no statistical significance (P > 0.050). The ApoA1 level of the T carriers was statistically significantly higher than the C carriers in males (t = -2.383, P = 0.020); however, the ApoB and lipid levels were not associated with rs2897827 (P > 0.050). In female patients, no significant difference was observed between different genotypic/allelic carriers in serum apolipoprotein and lipid levels (all P > 0.050). The expression of the TLR7 gene may affect IS occurrence. TLR7 gene rs2897827 may influence TLR7 mRNA expression and the plasma ApoA1 level in male IS patients.

Genotypic distribution of common variants of endosomal toll like receptors in healthy Spanish women. A comparative study with other populations

Genetic variants of endosomal toll like receptors (TLR) have been associated with many infectious, autoimmune and inflammatory diseases, but few studies have been reported in the Spanish population. The aim of this study was to describe the allelic and genotypic distributions of some common nucleotide substitutions of endosomal TLRs in healthy Spanish women and to compare them with those already published in other population groups. Nine substitutions were analysed in 150 DNA samples from 150 Spanish, non-related healthy females: TLR3 rs3775291 and rs5743305; TLR7 rs179008 and rs5743781; TLR8 rs3764880 and TLR9 rs187084, rs5743836, rs352139 and rs352140. Genotyping was carried out by real time PCR and melting curve analysis in a LightCycler 480. A systematic review was performed in order to compare the genotypic distributions in our cohort with those previously published in other population groups. The comparative study was performed with the two tailed Fisher's test or the Yates continuity correction for the Chi-square test when appropriate. No homozygotes for rs5743781 in TLR7 were found, and rs352139 and rs352140 of TLR9 were in strong linkage disequilibrium. Genotype distributions in endosomal TLR are similar to other Spanish series previously reported. As expected, most differences were found when comparing our distributions with Asiatics, but differences were also found with other Caucasian populations. Since there are significant variations in genotypic distributions of TLRs in both interracial groups and within the same ethnic group, to carry out studies of disease susceptibility in more restricted groups is mandatory.

An interleukin-1 beta-encoding retrovirus exhibits enhanced replication in vivo

Interleukin-1 beta (IL-1β) is an inflammatory cytokine that is secreted in response to inflammasome activation by innate microbe-sensing pathways. Although some retroviruses can trigger IL-1β secretion through the DNA-sensing molecule IFI16, the effect of IL-1β on the course of infection is unknown. To test whether IL-1β secretion affects retroviral replication in vivo, I constructed a novel murine leukemia virus strain (FMLV-IL-1β) that encodes the mature form of IL-1β. This virus replicated with kinetics similar to that of wild-type virus in tissue culture but caused a dramatically more aggressive infection of both C57BL/6 and BALB/c mice. By 7 days postinfection (PI), mice infected with FMLV-IL-1β exhibited splenomegaly and viral loads 300-fold higher than those in mice infected with wild-type FMLV. Furthermore, the enlarged spleens of FMLV-IL-1β-infected mice correlated with a large expansion of Gr-1(+) CD11b(+) myeloid-derived suppressor cells, as well as elevated levels of immune activation. Although FMLV-IL-1β infection was controlled by C57BL/6 mice by 14 days p.i., FMLV-IL-1β was able to establish a significant persistent infection and immune activation in BALB/c mice. These results demonstrate that IL-1β secretion is a powerful positive regulator of retroviral infection and that FMLV-IL-1β represents a new model of proinflammatory retroviral infection.

IMPORTANCE

Interleukin-1 beta (IL-1β) is an inflammatory cytokine released in response to activation of innate pathogen-sensing pathways during microbial infection. To examine the potential impact of IL-1β on retroviral replication in vivo, I constructed a novel mouse retrovirus strain (FMLV-IL-1β) that encodes IL-1β and promotes abundant IL-1β secretion from infected cells. This virus replicates with normal kinetics in cultured cells but displays a dramatically enhanced ability to replicate in mice and caused persistent infection and immune activation in the BALB/c strain of mice. These results establish IL-1β as a positive regulator of retroviral replication and suggest that targeting this pathway may have therapeutic benefits in infections with proinflammatory retroviruses. This virus can also be used to further study the impact of inflammatory pathways on retroviral infection.