Correlations between TLR polymorphisms and inflammatory bowel disease: a meta-analysis of 49 case-control studies

Pogostemon cablin Acts as a Key Regulator of NF-κB Signaling and Has a Potent Therapeutic Effect on Intestinal Mucosal Inflammation

Persistent intestinal inflammation is a major contributor to various diseases, including digestive disorders, immune dysregulation, and cancer. The NF-κB signaling pathway is pivotal in the inflammatory response of intestinal cells, regulating the secretion of inflammatory factors, mediating signal transduction, and activating receptors. In colitis, NF-κB signaling and its effector molecules are excessively activated by various stimuli, leading to overexpression of inflammatory mediators and immune regulators. Colitis, an inflammation of the intestinal mucosa, underlies many intestinal diseases, with increasing incidence. Traditional treatments such as glucocorticoids and nonsteroidal antiinflammatory drugs have significant limitations and side effects. Pogostemon cablin, a traditional Chinese medicine and food, is widely used in food, spices, and pharmaceuticals. Studies have demonstrated its positive therapeutic effects on intestinal inflammation, primarily through regulation of the NF-κB signaling pathway. Moreover, P. cablin and its active components exhibit pharmacological activities such as antiapoptotic, antioxidant, and antitumor effects. This review summarizes the original research on treating intestinal mucosal inflammation via NF-κB signaling regulation using P. cablin and its active components, providing new insights for colitis treatment.

Synonymous mutations in TLR2 and TLR9 genes decrease COPD susceptibility in the Chinese Han population

INTRODUCTION

Previous studies have found associations between polymorphisms in some candidate genes and chronic obstructive pulmonary disease (COPD) risk. However, the association between TLR2 and TLR9 polymorphisms and COPD risk remains uncertain.

METHODS

Four variants (rs352140, rs3804099, rs3804100, and rs5743705) of the TLR2 and TLR9 genes in 540 COPD patients and 507 healthy controls were genotyped using the Agena MassARRAY system. Odds ratio (OR) and 95% confidence interval (CI) were calculated to assess the association of TLR2 and TLR9 polymorphisms with COPD risk by logistic regression analysis.

RESULTS

TLR9-rs352140, TLR2-rs3804100, and TLR2-rs5743705 were related to a lower risk of COPD among Chinese people and the significance still existed after Bonferroni correction. Additionally, rs3804099, rs3804100, and rs352140 were found to be associated with COPD development in different subgroups (males, age ≤ 68 years, smokers, BMI < 24 kg/m2, and acute exacerbation).

CONCLUSIONS

Our findings indicated that TLR9 and TLR2 polymorphisms had protective effects on the development of COPD among Chinese people.

Potential role of SNP rs2071475 in rheumatoid arthritis and inflammatory bowel disease in the East Asian population: a Mendelian randomization study

BACKGROUND

Previous observational studies have identified an association between rheumatoid arthritis (RA) and inflammatory bowel disease (IBD). However, the causal relationship between RA and IBD in the East Asian population remains uncertain.

METHODS

The two-sample Mendelian randomization (MR) analysis was conducted to elucidate the potential causal relationship between RA and IBD. Summary-level data from genome-wide association studies (GWAS) in the East Asian population were utilized, including RA (n = 19,190) and IBD (n = 6543), including Crohn's disease (CD, n = 5409) and ulcerative colitis (UC, n = 4853). The inverse variance weighted (IVW) method was employed as the primary analysis, supplemented by weighted median, weighted mode, simple median, MR-Egger, and MR-PRESSO analyses. Sensitivity analyses were conducted to assess the robustness of the results. Genetic data for RA (n = 22,515) were utilized to validate the findings in the East Asian population.

RESULTS

The IVW method showed no significant association between genetically predicted RA and overall IBD in the East Asian population (OR = 1.028; 95% CI: 0.935-1.129; P = 0.567). The subgroup analysis revealed a positive association between RA and CD (OR = 1.268; 95% CI: 1.108-1.451; P < 0.001), while a negative association was observed with UC (OR = 0.839; 95% CI: 0.710-0.993; P = 0.041). These findings were supported by another set of RA data. Additionally, an SNP rs2071475 was identified to play an important role in CD and UC.

CONCLUSION

This study revealed a potential increased susceptibility to CD and a decreased susceptibility to UC in the East Asian population with RA. Furthermore, a key SNP rs2071475 was discovered along with its opposite effects in CD and UC. These findings provide new evidence for research on the corresponding molecular mechanisms and offer insights for clinical management of RA-associated IBD.

The association of TLR4 gene polymorphisms with the severity of peritonitis in acute inflammatory diseases of the abdominal cavity organs

OBJECTIVE

Aim: To determine the role of TLR4 gene polymorphisms as risk factors for peritonitis severity in patients undergoing surgery for acute inflammatory diseases of the abdominal cavity.

PATIENTS AND METHODS

Materials and Methods: The study included 139 patients who were operated on for acute abdominal diseases (acute appendicitis and cholecystitis, perforated gastric or duodenal ulcer, etc.). Depending on the number of points on the modified APACHE II scale, patients were divided into two groups: Group 1 - 1-3 points (63 patients, 45.3%) and Group 2 - 4 or more points (76 patients, 54.7%). Polymorphisms rs1927911, rs2149356 and rs4986790 were determined by polymerase chain reaction.

RESULTS

Results: The rs1927911 polymorphism of the TLR4 gene was protective for the development of peritonitis (according to the allelic model, OR 0.48; 95% CI 0.27-0.84; p=0.015). Regression analysis revealed a reduced (p=0.015) risk of severe peritonitis in rs1927911 A/A or G/A genotype carriers (OR 0.42; 95% CI 0.21-0.84) compared with G/G genotype carriers. There was no effect on the severity of peritonitis of TLR4 polymorphisms rs2149356 and rs4986790. There was a tendency to increase the frequency of the mutant G rs4986790 allele in patients with severe peritonitis (χ2=2.17; p<0.001). The analysis of the association of TLR4 gene polymorphisms with the phenotype of patients showed that carriers of mutant homozygotes and heterozygotes in the presence of severe peritonitis were older, had a tendency to coagulopathy, higher leukocytosis and leukocyte clotting rate.

CONCLUSION

Conclusions: Thus, the importance of TLR in the development of severe peritonitis was confirmed and the protective role of the rs1927911 promoter polymorphism was established.

Toll-like receptors in inflammatory bowel disease: A review of the role of phytochemicals

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic inflammation within the gastrointestinal tract with a remarkable impact on patients' quality of life. Toll-like receptors (TLR), as a key contributor of immune system in inflammation, has a critical role in the pathogenesis of IBD and thus, can be a suitable target of therapeutic agents. Medicinal plants have long been considered as a source of bioactive agents for different diseases, including IBD.

PURPOSE

This review discusses current state of the art on the role of plant-derived compounds for the management of IBD with a focus on TLRs.

METHODS

Electronic database including PubMed, Web of Science, and Scopus were searched up to January 2023 and all studies in which anticolitis effects of a phytochemical was assessed via modulation of TLRs were considered.

RESULTS

Different categories of phytochemicals, including flavonoids, lignans, alkaloids, terpenes, saccharides, and saponins have demonstrated modulatory effects on TLR in different animal and cell models of bowel inflammation. Flavonoids were the most studied phytochemicals amongst others. Also, TLR4 was the most important type of TLRs which were modulated by phytochemicals. Other mechanisms such as inhibition of pro-inflammatory cytokines, nuclear factor-κB pathway, nitric oxide synthesis pathway, cyclooxygenase-2, lipid peroxidation, as well as induction of endogenous antioxidant defense mechanisms were also reported for phytochemicals in various IBD models.

CONCLUSION

Taken together, a growing body of pre-clinical evidence support the efficacy of herbal compounds for the treatment of IBD via modulation of TLRs. Future clinical studies are recommended to assess the safety and efficacy of these compounds in human.

Gut Microbiota, Inflammatory Bowel Disease, and Cancer: The Role of Guardians of Innate Immunity

Inflammatory bowel diseases (IBDs) are characterized by a persistent low-grade inflammation that leads to an increased risk of colorectal cancer (CRC) development. Several factors are implicated in this pathogenetic pathway, such as innate and adaptive immunity, gut microbiota, environment, and xenobiotics. At the gut mucosa level, a complex interplay between the immune system and gut microbiota occurs; a disequilibrium between these two factors leads to an alteration in the gut permeability, called 'leaky gut'. Subsequently, an activation of several inflammatory pathways and an alteration of gut microbiota composition with a proliferation of pro-inflammatory bacteria, known as 'pathobionts', take place, leading to a further increase in inflammation. This narrative review provides an overview on the principal Pattern Recognition Receptors (PRRs), including Toll-like receptors (TLRs) and NOD-like receptors (NLRs), focusing on their recognition mechanisms, signaling pathways, and contributions to immune responses. We also report the genetic polymorphisms of TLRs and dysregulation of NLR signaling pathways that can influence immune regulation and contribute to the development and progression of inflammatory disease and cancer.

M2a macrophages facilitate resolution of chemically-induced colitis in TLR4-SNP mice

IMPORTANCE

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, impacts millions of individuals worldwide and severely impairs the quality of life for patients. Dysregulation of innate immune signaling pathways reduces barrier function and exacerbates disease progression. Macrophage (Mφ) signaling pathways are potential targets for IBD therapies. While multiple treatments are available for IBD, (i) not all patients respond, (ii) responses may diminish over time, and (iii) treatments often have undesirable side effects. Genetic studies have shown that the inheritance of two co-segregating SNPs expressed in the innate immune receptor, TLR4, is associated with human IBD. Mice expressing homologous SNPs ("TLR4-SNP" mice) exhibited more severe colitis than WT mice in a DSS-induced colonic inflammation/repair model. We identified a critical role for M2a "tissue repair" Mφ in the resolution of colitis. Our findings provide insight into potential development of novel therapies targeting Mφ signaling pathways that aim to alleviate the debilitating symptoms experienced by individuals with IBD.

Role of intergenic interactions between cytokine and Toll-like receptor genes in the etiology of congenital heart defects

The incidence of congenital heart defects (CHDs) reaches 1% of all newborns. Of particular importance is the group of heart defects without a family history and chromosomal disorders, which makes up>80% of all CHDs. These heart defects can be designated as sporadic CHDs, and their etiology and pathogenesis continue to be studied.

Aim. To study the association of cytokine and Toll-like receptor (TLR) genes with CHDs in children.

Material and methods. We examined 188 children with sporadic (without family history) CHDs (main group) and 103 healthy children without CHDs (control group). Genotyping was performed by real-time polymerase chain reaction (PCR).

Results. Sporadic CHDs, in general, and septal CHDs, in particular, are formed on similar intergenic associations that determine the dysregulation of the proliferation and differentiation of progenitor cells of the cardiovascular system. Probably, one of the molecular mechanisms for sporadic septal CHDs may be the inefficiency of intracellular signaling pathways for Nuclear Factor kappa B (NF-κB) due to the primary deficiency of membrane heterodimers TLR1/TLR6, TLR2/TLR6, and TLR1/TLR2.

Conclusion. Data on altered proinflammatory potential in the group of sporadic septal CHDs should be taken into account in the postnatal period when conducting cardiac surgery.

Single Nucleotide Polymorphisms of Toll-like Receptor 4 in Hepatocellular Carcinoma-A Single-Center Study

Hepatocellular carcinoma (HCC) is the most common primary liver tumor leading to significant morbidity and mortality; its exact genetic background is largely unrecognized. Toll-like receptor-4 (TLR4) reacts with lipopolysaccharides, molecules found in the outer membrane of Gram-negative bacteria. In damaged liver, TLR4 expression is upregulated, leading to hepatic inflammation and injury. We tried to investigate the role of the two most common single-nucleotide polymorphisms (SNPs) of TLR4 in HCC-genesis. Aged > 18 years old, cirrhotic patients were included in this study. Exclusion criteria were non-HCC tumors and HIV co-infection. TLR4 SNPs association with HCC occurrence was the primary endpoint, and associations with all-cause and liver-related mortality, as well as time durations between diagnosis of cirrhosis and HCC development or death and diagnosis of HCC and death were secondary endpoints. A total of 52 out of 260 included patients had or developed HCC. TLR4 SNPs showed no correlation with primary or secondary endpoints, except for the shorter duration between HCC development and death in patients with TLR4 mutations. Overall, TLR4 SNPs showed no correlation with carcinogenesis or deaths in patients with liver cirrhosis; patients with TLR4 SNPs that developed HCC had lower survival rates, a finding that should be further evaluated.

Factors Modulating COVID-19: A Mechanistic Understanding Based on the Adverse Outcome Pathway Framework

Addressing factors modulating COVID-19 is crucial since abundant clinical evidence shows that outcomes are markedly heterogeneous between patients. This requires identifying the factors and understanding how they mechanistically influence COVID-19. Here, we describe how eleven selected factors (age, sex, genetic factors, lipid disorders, heart failure, gut dysbiosis, diet, vitamin D deficiency, air pollution and exposure to chemicals) influence COVID-19 by applying the Adverse Outcome Pathway (AOP), which is well-established in regulatory toxicology. This framework aims to model the sequence of events leading to an adverse health outcome. Several linear AOPs depicting pathways from the binding of the virus to ACE2 up to clinical outcomes observed in COVID-19 have been developed and integrated into a network offering a unique overview of the mechanisms underlying the disease. As SARS-CoV-2 infectibility and ACE2 activity are the major starting points and inflammatory response is central in the development of COVID-19, we evaluated how those eleven intrinsic and extrinsic factors modulate those processes impacting clinical outcomes. Applying this AOP-aligned approach enables the identification of current knowledge gaps orientating for further research and allows to propose biomarkers to identify of high-risk patients. This approach also facilitates expertise synergy from different disciplines to address public health issues.

Inflammatory factors, genetic variants, and predisposition for preterm birth

Preterm birth is a major clinical and public health challenge, with a prevalence of 11% worldwide. It is the leading cause of death in children younger than 5 years old and represents 70% of neonatal deaths and 75% of neonatal morbidity. Despite the clinical and public health significance, this condition's etiology is still unclear, and most of the cases are spontaneous. There are several known preterm birth risk factors, including inflammatory diseases and the genetic background, although the underlying molecular mechanisms are far from understood. The present review highlights the research advances on the association between inflammatory-related genes and the increased risk for preterm delivery. The most associated genetic variants are the TNFα rs1800629, the IL1α rs17561, and the IL1RN rs2234663. Moreover, many of the genes discussed in this review are also implicated in pathologies involving inflammatory or autoimmune systems, such as periodontal disease, bowel inflammatory disease, and autoimmune rheumatic diseases. This review presents evidence suggesting a common genetic background to preterm birth, autoimmune and inflammatory diseases susceptibility.

Toll-like receptor gene polymorphisms in patients with keratitis

OBJECTIVE

To investigate differences in SNPs in TLR genes between people who had keratitis and controls in an Indian population.

METHODS

145 cases of keratitis and 189 matched controls were recruited. DNA was extracted from peripheral blood. Single nucleotide polymorphisms (SNP) in TLR2 (n = 6), TLR4 (n = 15), TLR5 (n = 13) and TLR9 (n = 10) were analysed. The risk of developing keratitis was assessed based on allele, genotype and haplotype associations.

RESULTS

For all cases of keratitis, the TLR4 SNP rs4986791 TC genotype frequency was significantly higher in cases (p = 0.006, OR = 1.96, 95 % CI 1.19-3.2). Including cases of only microbial keratitis (MK) revealed that genotypes in TLR2 SNP rs5743706 TA (p = 0.0001; OR = 8.61; 95 % CI 2.59-28.56)), TLR4 SNP s4986791 TC (p = 0.002; OR = 2.65; 95 % CI 1.39-5.07) were significantly more common for MK, whereas the TLR5 SNP rs2241096 A allele (p = 0.00316, OR = 0.42, 95 % CI 0.2-0.9286) and GA genotype (p = 0.016; OR = 0.45; 95 % CI 0.23-0.86) was significantly less common in MK cases. The TLR2 SNP rs5743706 genotype TA was significantly less common in the sterile keratitis (SK) group (p = 0.004, OR = 0.43, 95 %CI 0.24-0.77). Haplotype analysis of MK compared to controls showed that TLR2 AT was more common in controls (p = 0.003); TLR4 ACAC was more common in cases (p = 0.004); TLR5 TGGCA was more common in controls (p = 0.001).

CONCLUSION

The present study revealed multiple associations between variants across TLR genes, which may have implications for understanding the underlying host factors, risk of developing keratitis and molecular pathogenesis in keratitis.

NFKB2 polymorphisms associate with the risk of developing rheumatoid arthritis and response to TNF inhibitors: Results from the REPAIR consortium

This study sought to evaluate the association of 28 single nucleotide polymorphisms (SNPs) within NFKB and inflammasome pathway genes with the risk of rheumatoid arthritis (RA) and response to TNF inhibitors (TNFi). We conducted a case-control study in a European population of 1194 RA patients and 1328 healthy controls. The association of potentially interesting markers was validated with data from the DANBIO (695 RA patients and 978 healthy controls) and DREAM (882 RA patients) registries. The meta-analysis of our data with those from the DANBIO registry confirmed that anti-citrullinated protein antibodies (ACPA)-positive subjects carrying the NFKB2_rs11574851T allele had a significantly increased risk of developing RA (PMeta_ACPA + = 0.0006) whereas no significant effect was found in ACPA-negative individuals (PMeta_ACPA- = 0.35). An ACPA-stratified haplotype analysis including both cohorts (n = 4210) confirmed that ACPA-positive subjects carrying the NFKB2_TT haplotype had an increased risk of RA (OR = 1.39, P = 0.0042) whereas no effect was found in ACPA-negative subjects (OR = 1.04, P = 0.82). The meta-analysis of our data with those from the DANBIO and DREAM registries also revealed a suggestive association of the NFKB2_rs1056890 SNP with larger changes in DAS28 (OR = 1.18, P = 0.007). Functional experiments showed that peripheral blood mononuclear cells from carriers of the NFKB2_rs1005044C allele (in LD with the rs1056890, r2 = 1.00) showed increased production of IL10 after stimulation with LPS (P = 0.0026). These results provide first evidence of a role of the NFKB2 locus in modulating the risk of RA in an ACPA-dependent manner and suggest its implication in determining the response to TNFi. Additional studies are now warranted to further validate these findings.

Expression of TLR2 and TLR5 in distal ileum of mice with obstructive jaundice and their role in intestinal mucosal injury

INTRODUCTION

The aim was to investigate the expression of TLR2 and TLR5 in the distal ileum of mice with obstructive jaundice (OJ) and their role in intestinal mucosal injury.

MATERIAL AND METHODS

A total of 100 male C57BL/6J mice were randomly assigned to two groups: (I) sham operation (SH); (II) bile duct ligation (BDL). The mice were respectively sacrificed before operation and on the 1st, 3rd, 5th and 7th days after operation to collect specimens. Various indicators were detected by PCR, immunohistochemistry and other methods.

RESULTS

TLR2 was increased gradually with the extension of OJ time in the BDL group (p < 0.05). However, the changes in the expression of TLR5 were not obvious at different time points. The amount of Bifidobacteria and Lactobacillus showed downward trends in intestinal tract of the BDL group. Furthermore, the amount of Escherichia coli was increased in intestinal tract of the BDL group. The pathological score of intestinal mucosa and the expression of NF-κB increased gradually in the BDL group with the extension of OJ time. There were positive correlations between the pathological score of intestinal mucosa and expressions of TLR2(r = 0.767, p < 0.05) and NF-κB (r = 0.817, p < 0.05) in BDL group. NF-κB expression was positively correlated with TLR2 expression(r = 0.706, p < 0.05).

CONCLUSIONS

Disturbance of intestinal flora caused by OJ could increase the expression of NF-κB via up-regulating the expression of TLR2 to activate the downstream signaling pathway, thus aggravated the injury of intestinal mucosa.