Polymorphisms of toll-like receptors 2 and 9 and severity and prognosis of bacterial meningitis in Chinese children

Association of the Single Nucleotide Polymorphism 19216T/C in the TLR2 Gene (rs3804099) with Entamoeba histolytica/Entamoeba dispar/Entamoeba moshkovskii Infection Among Lebanese Children

Toll-like receptors (TLRs), particularly the TLR2, take part in the elicitation of immune responses against Entamoeba histolytica. This study aimed to investigate the relationship between a specific polymorphism called rs3804099 in the TLR2 gene and E. histolytica/E. dispar/E. moshkovskii infection among Lebanese children. A case-control study encompassed 180 participants including 68 children with amebiasis and 112 matched controls. Blood samples were collected, and genomic DNA was extracted using the classical proteinase K digestion and phenol-chloroform extraction method. The variant rs3804099 was examined using the Amplification Refractory Mutation System Polymerase Chain Reaction. The accuracy of the genotyping was supported by sequencing 5% of samples. The TLR2 rs3804099 polymorphism was identified in the studied population, and the observed genotypic distributions were consistent with Hardy-Weinberg equilibrium (P > 0.05). The frequency of the rare CC genotype was significantly higher in patients compared to the noninfected group (P < 0.01). In controls, the homozygous TT genotype was less frequent than the heterozygous CT genotype. The rare CC genotype was associated with a higher risk of amebiasis among children (odds ratios = 3.27, P = 0.002). These findings provide evidence supporting the association between the rs3804099 SNP in the TLR2 gene and E. histolytica/E. dispar/E. moshkovskii infection among Lebanese children.

Potential of Neuroinflammation-Modulating Strategies in Tuberculous Meningitis: Targeting Microglia

Tuberculous meningitis (TBM) is the most severe complication of tuberculosis (TB) and is associated with high rates of disability and mortality. Mycobacterium tuberculosis (M. tb), the infectious agent of TB, disseminates from the respiratory epithelium, breaks through the blood-brain barrier, and establishes a primary infection in the meninges. Microglia are the core of the immune network in the central nervous system (CNS) and interact with glial cells and neurons to fight against harmful pathogens and maintain homeostasis in the brain through pleiotropic functions. However, M. tb directly infects microglia and resides in them as the primary host for bacillus infections. Largely, microglial activation slows disease progression. The non-productive inflammatory response that initiates the secretion of pro-inflammatory cytokines and chemokines may be neurotoxic and aggravate tissue injuries based on damages caused by M. tb. Host-directed therapy (HDT) is an emerging strategy for modulating host immune responses against diverse diseases. Recent studies have shown that HDT can control neuroinflammation in TBM and act as an adjunct therapy to antibiotic treatment. In this review, we discuss the diverse roles of microglia in TBM and potential host-directed TB therapies that target microglia to treat TBM. We also discuss the limitations of applying each HDT and suggest a course of action for the near future.

Interactions between CNS and immune cells in tuberculous meningitis

The central nervous system (CNS) harbors its own special immune system composed of microglia in the parenchyma, CNS-associated macrophages (CAMs), dendritic cells, monocytes, and the barrier systems within the brain. Recently, advances in the immune cells in the CNS provided new insights to understand the development of tuberculous meningitis (TBM), which is the predominant form of Mycobacterium tuberculosis (M.tb) infection in the CNS and accompanied with high mortality and disability. The development of the CNS requires the protection of immune cells, including macrophages and microglia, during embryogenesis to ensure the accurate development of the CNS and immune response following pathogenic invasion. In this review, we summarize the current understanding on the CNS immune cells during the initiation and development of the TBM. We also explore the interactions of immune cells with the CNS in TBM. In the future, the combination of modern techniques should be applied to explore the role of immune cells of CNS in TBM.

Polymorphisms and haplotypes of TLR-4/9 associated with bacterial infection, gingival inflammation/recession and oral cancer

BACKGROUND

The expression and SNPs of innate immunity genes TLR-4/9 for bacterial infection, gingival inflammation/gingival recession (GIGR), and oral squamous cell carcinoma (OSCC) are largely unknown.

PATIENTS AND METHOD

235 specimens (120 OSCC cases, among which 85 cases with either Porphyromonas gingivalis, Fusobacterium nucleatum or Treponema denticola infection and GIGR) and 115 healthy controls were used to know the expression and polymorphisms (TLR-4: N1:rs10759931, N2:rs11536889, N3:rs1927911, N4:rs4986790; TLR-9: N5:rs5743836, N6:rs352140, N7:rs187084 and N8:rs352139) of TLR-4/9 by western blot, RT-PCR, and allele-specific (AS)-PCR followed by sequencing.

RESULTS

Increased TLR-4/9 mRNA/protein expression, bacterial infection (BI) and GIGR were associated with OSCC incidence. One of the three BI and GIGR was observed in 70.83% of OSCC cases, whereas all the HC used were free from any of these three BI/GIGR. The N3: CT-genotype (Odds Ratio hereafter as O.R.=1.811, p = 0.0338), TT-genotype (O.R.=3.094, p = 0.0124), 'T'-allele (O.R.=1.821, p = 0.003), N4: AG-genotype (O.R.=2.015, p = 0.0222) and 'G'-allele (O.R.=1.86, p = 0.018) of TLR-4 as well as the N5: CC-genotype (O.R.=3.939, p = 0.0017), 'C'-allele (O.R.=1.839, p = 0.0042), N6: AA-genotype (O.R.=2.195, p = 0.0234), 'A'-allele (O.R.=1.569, p = 0.0163), N7: TC-genotype (O.R.=2.083, p = 0.0136), CC-genotype (O.R.=2.984, p = 0.003) and 'C'-allele (O.R.=1.885, p = 0.0008) of TLR-9 were associated with increased OSCC risk. Similarly, the N2:'C'-allele (O.R.=1.615, p = 0.0382), N3: TT-genotype (O.R.=2.829, p = 0.0336), 'T'-allele (O.R.=1.742, p = 0.0115), N4: AG-genotype (O.R.=2.221, p = 0.0147) and 'G'-allele (O.R.=1.890, p = 0.0238) of TLR-4 as well as the N5: CC-genotype (O.R.=2.830, p = 0.031), N6: AA-genotype (O.R.=2.6, p = 0.0122) and 'A'-allele (O.R.=1.746, p = 0.0064), N7:CC-genotype (O.R.2.706, p = 0.0111) and 'C'-allele (O.R. 1.774, p = 0.0055) of TLR-9 were correlated with GIGR and BI. TLR-4 (N1-N2-N3-N4: A-C-T-A (O.R.=2.1, p = 0.0069) and TLR-9 (N5-N6-N7-N8: T-A-C-A (O.R.=2.019, p = 0.0263); C-A-C-A (O.R.=6.0, p = 0.0084); C-A-C-G (O.R.=4.957, p = 0.0452) haplotypes were linked with OSCC vulnerability, while the TLR-4 (N1-N2-N3-N4: G-C-C-A (O.R.=0.5752, p = 0.0131) and TLR-9 (N5-N6-N7-N8: T-G-T-A (O.R.=0.5438, p = 0.0314); T-G-T-G (O.R.=0.5241, p = 0.036) haplotypes offered protection.

CONCLUSION

TLR-4/9 expression, polymorphisms, and BI-induced GIGR could increase OSCC risk. This may be used in pathogenesis and oral cancer prediction.

Association of TLR3 gene 1377C/T (rs3775290) and TLR7 gene C/G (rs3853839) polymorphism with hand, foot, and mouth disease caused by human enterovirus 71 infection susceptibility and severity in the Chinese Han population: A meta-analysis of case-control studies

BACKGROUND

Several case-control studies have been conducted on the relationship between rs3775290 C/T and rs3853839 C/G single nucleotide polymorphisms of the Toll-like receptor (TLR) gene and hand, foot, and mouth disease (HFMD) susceptibility and severity. This meta-analysis aimed to offer a systemic review of HFMD susceptibility and severity among the Chinese Han population associated with the C/T (rs3775290) polymorphism of the TLR3 gene or C/G (rs3853839) polymorphism of the TLR7 gene.

METHODS

A computer search was conducted using PubMed, Web of Science, Embase, CNKI, CBM, VIP, and WanFang databases. The time ranges were from database establishment to 30/7/2021. Articles selected according to the inclusion and exclusion criteria underwent data extraction and methodological quality evaluation. RevMan 5.4 and Stata 16.0 were adopted for meta-analysis, and the incorporated odds ratio (OR) values and 95% confidence intervals (CIs) were calculated. Sensitivity and publication bias assessments were performed.

RESULTS

8 articles with 9 studies were selected. Among them, there were 858 cases and 577 controls in TLR3 rs3775290 studies as well as 2151 cases and 1554 controls in TLR7 rs3853839 studies. Regarding rs3775290 of TLR3, susceptibilities of the severe type of T-possessing individuals were larger than those of C-possessing individuals [OR = 1.34, 95%CI (1.10, 1.64), P = .004]. The susceptibility of individuals with the severe TT genotype was 1.61 times that of individuals with the CC genotype [95%CI (1.07, 2.43), P=0.02], while susceptibility to HFMD was not influenced by the genotype. In terms of the rs3853839 of the TLR7 gene, C allele carriers have a higher risk of developing HFMD than G allele carriers. The susceptibility to HFMD in CC+CG individuals was 1.24 times than that in GG individuals [95%CI (1.07, 1.43), P = .004]. However, no relationship was found between this polymorphism and severity of the severe type. No significant publication bias was observed in this study.

CONCLUSIONS

rs3775290 (C/T) of TLR3 is associated with susceptibility to the severe type, whereas rs3853839 (C/G) of TLR7 is associated with susceptibility to HFMD. However, owing to the limited quantity and quality of the research, the aforementioned conclusions are yet to be justified by more high-quality research.

Association of Single Nucleotide Polymorphisms from Angiogenesis-Related Genes, ANGPT2, TLR2 and TLR9, with Spontaneous Preterm Labor

In this study, we hypothesized that the changes localized at angiopoietin-2 (ANGPT2), granulocyte-macrophage colony-stimulating factor (CSF2), fms-related tyrosine kinase 1 (FLT1) and toll-like receptor (TLR) 2, TLR6 and TLR9 genes were associated with spontaneous preterm labor (PTL), as well as with possible genetic alterations on PTL-related coagulation. This case-control genetic association study aimed to identify single nucleotide polymorphisms (SNPs) for the aforementioned genes, which are correlated with genetic risk or protection against PTL in Polish women. The study was conducted in 320 patients treated between 2016 and 2020, including 160 women with PTL and 160 term controls in labor. We found that ANGPT2 rs3020221 AA homozygotes were significantly less common in PTL cases than in controls, especially after adjusting for activated partial thromboplastin time (APTT) and platelet (PLT) parameters. TC heterozygotes for TLR2 rs3804099 were associated with PTL after correcting for anemia, vaginal bleeding, and history of threatened miscarriage or PTL. TC and CC genotypes in TLR9 rs187084 were significantly less common in women with PTL, compared to the controls, after adjusting for bleeding and gestational diabetes. For the first time, it was shown that three polymorphisms-ANGPT2 rs3020221, TLR2 rs3804099 and TLR9 rs187084 -were significantly associated with PTL, adjusted by pregnancy development influencing factors.

Genetic variations of toll-like receptors: Impact on susceptibility, severity and prognosis of bacterial meningitis

Bacterial meningitis (BM) is a serious infectious disease of the central nervous system，which is mainly caused by Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Group B Streptococcus and Listeria monocytogenes. Throughout the world, BM has become one of the most lethal diseases that commonly occurs in children. Toll like receptors (TLRs) are one of the most important immune defense lines in infectious diseases, and play an essential role in host defense. Accumulating evidence shows that genetic variations in TLRs are associated with host responses in BM. This review aims to summarize the role of different TLRs and their genetic variations in the susceptibility, severity and prognosis of BM and discuss the identified risk factors for better treatment and improvement of the course and outcome of BM.

The Potentials of Melatonin in the Prevention and Treatment of Bacterial Meningitis Disease

Bacterial meningitis (BM) is an acute infectious central nervous system (CNS) disease worldwide, occurring with 50% of the survivors left with a long-term serious sequela. Acute bacterial meningitis is more prevalent in resource-poor than resource-rich areas. The pathogenesis of BM involves complex mechanisms that are related to bacterial survival and multiplication in the bloodstream, increased permeability of blood-brain barrier (BBB), oxidative stress, and excessive inflammatory response in CNS. Considering drug-resistant bacteria increases the difficulty of meningitis treatment and the vaccine also has been limited to several serotypes, and the morbidity rate of BM still is very high. With recent development in neurology, there is promising progress for drug supplements of effectively preventing and treating BM. Several in vivo and in vitro studies have elaborated on understanding the significant mechanism of melatonin on BM. Melatonin is mainly secreted in the pineal gland and can cross the BBB. Melatonin and its metabolite have been reported as effective antioxidants and anti-inflammation, which are potentially useful as prevention and treatment therapy of BM. In bacterial meningitis, melatonin can play multiple protection effects in BM through various mechanisms, including immune response, antibacterial ability, the protection of BBB integrity, free radical scavenging, anti-inflammation, signaling pathways, and gut microbiome. This manuscript summarizes the major neuroprotective mechanisms of melatonin and explores the potential prevention and treatment approaches aimed at reducing morbidity and alleviating nerve injury of BM.

Gene Polymorphisms of TLR4 and TLR9 and Haemophilus influenzae Meningitis in Angolan Children

Bacterial meningitis (BM) is a severe disease caused by various bacterial pathogens. Toll-like receptors (TLRs) protect humans from invading pathogens. In this study, we determined whether single nucleotide polymorphisms (SNPs) of TLR4 and TLR9 are associated with susceptibility to and outcome of BM in Angolan children. Samples were taken from 241 patients and 265 age-matched ethnic controls. The SNPs TLR4 rs4986790 (896A > G) and TLR9 rs187084 (−1486T > C) were determined by high-resolution melting analysis (HRMA). The frequency of variant genotypes in TLR4 was significantly higher in patients with Haemophilus influenzae meningitis than controls (odds ratio (OR), 2.5; 95% confidence interval (CI), 1.2–5.4; p = 0.021), whereas the frequency of variant genotypes in TLR9 was significantly lower in patients with H. influenzae meningitis than controls (OR, 0.4; 95% CI, 0.2–0.9; p = 0.036). No such differences were found with other causative pathogens, such as Streptococcus pneumoniae and Neisseria meningitidis. At the time of discharge, patients with meningitis caused by Gram-negative bacteria who were carriers of variant TLR4 genotypes had a higher risk of ataxia (OR, 12.91; 95% CI, 1.52–109.80; p = 0.019) and other neurological sequelae (OR, 11.85; 95% CI, 1.07–131.49; p = 0.044) than those with the wild-type TLR4 genotype. Our study suggests an association between H. influenzae meningitis and genetic variation between TLR4 and TLR9 in Angolan children.

HIV-1 pseudoviruses constructed in China regulatory laboratory

To better evaluate HIV-1 vaccines and therapeutics, the National Institutes for Food and Drug Control of China developed a panel of HIV-1 pseudoviruses including 462 viral strains derived from China, covering the majority of contemporaneous subtypes and circulating recombinant forms. Compared with the standard pseudovirus panels derived from other countries/regions, the Chinese isolates are more susceptible to neutralization by the sera obtained in China, revealing the strain/subtype specificity. Some of these pseudoviruses have already been used for the evaluation of HIV vaccines and drug candidates in Chinese clinical trials. The pseudoviruses panel is widely shared with interested scientists involved in the research and development of vaccines and antiviral drugs against HIV-1 strains prevalent in China.

Toll-like receptors in the pathogenesis of neuroinflammation

Toll-like receptors (TLRs) are discovered as crucial pattern recognition receptors (PRRs) involved in the recognition of pathogen-associated molecular patterns (PAMPs). Later studies showed their involvement in the recognition of various damage/danger-associated molecular patterns (DAMPs) generated by host itself. Thus, TLRs are capable of recognizing wide-array of patterns/molecules derived from pathogens and host as well and initiating a proinflammatory immune response through the activation of NF-κB and other transcription factors causing synthesis of proinflammatory molecules. The process of neuroinflammation is seen under both sterile and infectious inflammatory diseases of the central nervous system (CNS) and may lead to the development of neurodegeneration. The present article is designed to highlight the importance of TLRs in the pathogenesis of neuroinflammation under diverse conditions. TLRs are expressed by various immune cells present in CNS along with neurons. However out of thirteen TLRs described in mammals, some are present and active in these cells, while some are absent and are described in detail in main text. The role of various immune cells present in the brain and their role in the pathogenesis of neuroinflammation depending on the type of TLR expressed is described. Thereafter the role of TLRs in bacterial meningitis, viral encephalitis, stroke, Alzheimer's disease (AD), Parkinson's disease (PD), and autoimmune disease including multiple sclerosis (MS) is described. The article is designed for both neuroscientists needing information regarding TLRs in neuroinflammation and TLR biologists or immunologists interested in neuroinflammation.

Association of a single nucleotide polymorphism in the TLR2 gene (rs3804099), but not in the TLR4 gene (rs4986790), with Helicobacter pylori infection and peptic ulcer

BACKGROUND/AIMS

Toll-like receptors (TLRs), particularly TLR2 and TLR4, take part in elicitation of immune responses against Helicobacter pylori (H. pylori). This study aimed to investigate the relationship between single nucleotide polymorphisms (SNP) rs3804099 in the TLR2 gene and rs4986790 in the TLR4 gene with H. pylori infection and peptic ulcer (PU).

MATERIALS AND METHODS

Blood specimens were obtained from 350 individuals, including 100 H. pylori-infected patients with PU, 125 H. pylori-infected asymptomatic subjects (AS), and 125 non-infected healthy subjects (NHS). The DNA was extracted, and the SNPs were determined using ARMS-PCR method.

RESULTS

The frequency of CT genotype at TLR2 SNP rs3804099 in both the PU and AS groups was significantly higher than in the NHS group (p<0.05). In total H. pylori-infected individuals (PU+AS), the frequency of the CT genotype at rs3804099 was also significantly higher than in the NHS group (p<0.005). The frequency of the CC genotype at rs3804099 in PU+AS was markedly lower than in the NHS group (p=0.066). PU patients carried CT genotype more frequently than total healthy individuals (AS+NHS) (p<0.03). The distribution of the TT genotype was lower, whereas the frequency of the CT genotype was higher in AS individuals infected with CagA+ strains than those infected with CagA- strains (p<0.03). No significant differences were found among the PU, AS, and NHS groups regarding the genetic differences at rs4986790 in the TLR4 gene.

CONCLUSION

These results provide evidence regarding the association of the rs3804099 in the TLR2 gene with H. pylori infection and PU. The rs3804099 may affect vulnerability to H. pylori infection, particularly to CagA+ strains of bacteria.

Genes and their single nucleotide polymorphism involved in innate immune response in central nervous system in bacterial meningitis: review of literature data

Background

There are many studies analysing the effect of SNPs in genes coding proteins which are involved in innate immune response on susceptibility to invasive bacterial disease. Many of them gave inconclusive results. Regarding the complexity of immune response and cooperation between particular elements, number of SNPs may have a cumulative effect on the susceptibility to bacterial meningitis.

Findings

In most studies cooccurrence of several SNPs was not analysed. These studies were performed on small groups of patients and usually only few SNPs were checked simultaneously. Additionally, comparison of the results across the studies is hard to conduct. We hypothesise that the number of variants of genes involved in innate immune response plays a role in susceptibility to bacterial meningitis. However, the role of toll-like receptors and other part of innate immune response in the eradication of bacteria, and initiation of the inflammatory response in CNS need further studies.

Conclusion

Large multicentre studies assessing multiple SNPs in patients with microbiologically proven pneumococcal or meningococcal meningitis are needed to find real genetic risk factors for developing bacterial meningitis. This is necessary to design more effective treatment and prevention strategies for severe infections.

Meningococcal disease and control in China: Findings and updates from the Global Meningococcal Initiative (GMI)

The Global Meningococcal Initiative (GMI) is a global expert group, including scientists, clinicians and public health officials from a wide range of specialities. The goal of the GMI is to prevent meningococcal disease worldwide through education, research, and co-operation. The Chinese GMI roundtable meeting was held in June 2017. The GMI met with local experts to gain insight into the meningococcal disease burden in China and current prevention and vaccination strategies in place. China experienced five epidemics of serogroup A meningococcal disease (MenA) between 1938 and 1977, with peak incidence of 403/100,000 recorded in 1967. MenA incidence rates have significantly declined following the universal introduction of the MenA polysaccharide vaccine in China in the 1980s. Further, surveillance data indicates changing meningococcal epidemiology in China with the emergence of new clones of serogroup B from serogroup C clonal complex (cc) 4821 due to capsular switching, and the international spread of serogroup W cc11. The importance of carriage and herd protection for controlling meningococcal disease was highlighted with the view to introduce conjugate vaccines and serogroup B vaccines into the national immunization schedule. Improved disease surveillance and standardized laboratory techniques across and within provinces will ensure optimal epidemiological monitoring.

Lower frequency of TLR9 variant associated with protection from breast cancer among African Americans

Introduction

Toll-like receptor 9 (TLR9) is an innate immune system DNA-receptor that regulates tumor invasion and immunity in vitro. Low tumor TLR9 expression has been associated with poor survival in Caucasian patients with triple negative breast cancer (TNBC). African American (AA) patients with TNBC have worse prognosis than Caucasians but whether this is due to differences in tumor biology remains controversial. We studied the prognostic significance of tumor Toll like receptor-9 (TLR9) protein expression among African American (AA) triple negative breast cancer (TNBC) patients. Germline TLR9 variants in European Americans (EAs) and AAs were investigated, to determine their contribution to AA breast cancer risk.

Methods

TLR9 expression was studied with immunohistochemistry in archival tumors. Exome Variant Server and The Cancer Genome Atlas were used to determine the genetic variation in the general EA and AA populations, and AA breast cancer cases. Minor allele frequencies (MAFs) were compared between EAs (n = 4300), AAs (n = 2203), and/or AA breast cancer cases (n = 131).

Results

Thirty-two TLR9 variants had a statistically significant MAF difference between general EAs and AAs. Twenty-one of them affect a CpG site. Rs352140, a variant previously associated with protection from breast cancer, is more common in EAs than AAs (p = 2.20E-16). EAs had more synonymous alleles, while AAs had more rare coding alleles. Similar analyses comparing AA breast cancer cases with AA controls did not reveal any variant class differences; however, three previously unreported TLR9 variants were associated with late onset breast cancer. Although not statistically significant, rs352140 was observed less frequently in AA cases compared to controls. Tumor TLR9 protein expression was not associated with prognosis.

Conclusions

Tumor TLR9 expression is not associated with prognosis in AA TNBC. Significant differences were detected in TLR9 variant MAFs between EAs and AAs. They may affect TLR9 expression and function. Rs352140, which may protect from breast cancer, is 1.6 X more common among EAs. These findings call for a detailed analysis of the contribution of TLR9 to breast cancer pathophysiology and health disparities.