Associations of Toll-like Receptor Gene Polymorphisms with NETosis Activity as Prognostic Criteria for the Severity of Pneumonia

Neutrophil extracellular traps - a potential trigger for the development of thrombocytopenia during extracorporeal membrane oxygenation

Neutrophil extracellular traps (NETs) have recently emerged as a potential link between inflammation, immunity, and thrombosis, as well as other coagulation disorders which present a major challenge in the context of extracorporeal membrane oxygenation (ECMO). By examining blood from ECMO patients for NETs and their precursors and correlating them with clinical and laboratory biomarkers of coagulation and inflammation, this study aims to evaluate the association between the presence of NETs in the bloodstream of ECMO patients and the development of potentially severe coagulation disorders during ECMO therapy. Therefore, blood samples were collected from healthy volunteers (n=13) and patients receiving veno-venous (VV) ECMO therapy (n=10). To identify NETs and their precursors, DNA and myeloperoxidase as well as granulocyte marker CD66b were visualized simultaneously by immunofluorescence staining in serial blood smears. Differentiation of DNA-containing objects and identification of NETs and their precursors was performed semiautomatically by a specific algorithm using the shape and size of DNA staining and the intensity of MPO and CD66b signal. Neutrophil extracellular traps and their precursors could be detected in blood smears from patients requiring VV ECMO. Compared to volunteers, ECMO patients presented significantly higher rates of NETs and NET precursors as well as an increased proportion of neutrophil granulocytes in all detected nucleated cells. A high NET rate prior to the initiation of ECMO therapy was associated with both increased IL-6 and TNF-α levels as an expression of a high cytokine burden. These patients with increased NET release also presented an earlier and significantly more pronounced decrease in platelet counts and ATIII activity following initiation of therapy compared with patients with less elevated NETs. These findings provide further indications for the development of immune-mediated acquired thrombocytopenia in ECMO patients.

[Association of gene polymorphisms of MyD88 and TICAM1 and their interactions with community-acquired pneumonia in children]

OBJECTIVES

To investigate the association of single nucleotide polymorphisms (SNPs) of myeloid differentiation factor 88 (MyD88) and Toll-like receptor adaptor molecule 1 (TICAM1) and their interactions with community-acquired pneumonia (CAP) in children.

METHODS

Improved multiple ligase detection reaction assay was used for detecting the polymorphisms of nine tagging SNPs of the MyD88 and TICAM1 genes in 375 children with CAP who attended the Department of Pediatrics of the Second Affiliated Hospital of Yan'an University Medical School from August 2015 to September 2017 and 306 healthy children who underwent physical examination. A logistic regression analysis was used to evaluate the association between the distribution of genotypes and their interactions with CAP in children.

RESULTS

The polymorphism of the TICAM1 gene at rs11466711T/C locus was closely associated with the susceptibility to CAP in children (P<0.05). The AA genotype of rs35747610G/A locus significantly reduced risk of sepsis in children with CAP (P<0.05). The AA genotype of rs6510826G/A locus was significantly associated with the increase in C-reactive protein level in children with CAP (P<0.05). The GG genotype of the MyD88 gene at rs7744A/G locus significantly increased the risk of respiratory failure and circulatory failure (P<0.05). The multiplicative interactions between MyD88 gene rs7744A/G and TICAM1 gene rs11466711T/C, rs2292151G/A, rs35299700C/T, and rs35747610G/A loci were significantly associated with the susceptibility to CAP, the severity of CAP, and the risk of sepsis in children (P<0.05).

CONCLUSIONS

The gene polymorphisms of MyD88 and TICAM1 and their interactions are closely associated with CAP in children, with a synergistic effect on the development and progression of CAP in children.

TLRs Gene Polymorphisms Associated with Pneumonia before and during COVID-19 Pandemic

BACKGROUND

The progression of infectious diseases depends on the characteristics of a patient's innate immunity, and the efficiency of an immune system depends on the patient's genetic factors, including SNPs in the TLR genes. In this pilot study, we determined the frequency of alleles in these SNPs in a subset of patients with pneumonia.

METHODS

This study assessed six SNPs from TLR genes: rs5743551 (TLR1), rs5743708, rs3804100 (TLR2), rs4986790 (TLR4), rs5743810 (TLR6), and rs3764880 (TLR8). Three groups of patients participated in this study: patients with pneumonia in 2019 (76 samples), patients with pneumonia caused by SARS-CoV-2 in 2021 (85 samples), and the control group (99 samples).

RESULTS

The allele and genotype frequencies obtained for each group were examined using four genetic models. Significant results were obtained when comparing the samples obtained from individuals with pneumonia before the spread of SARS-CoV-2 and from the controls for rs5743551 (TLR1) and rs3764880 (TLR8). Additionally, the comparison of COVID-19-related pneumonia cases and the control group revealed a significant result for rs3804100-G (TLR2).

CONCLUSIONS

Determining SNP allele frequencies and searching for their associations with the course of pneumonia are important for personalized patient management. However, our results need to be comprehensively assessed in consideration of other clinical parameters.

Toll-Like Receptors (TLRs) in Health and Disease: An Overview

Toll-like receptors were discovered as proteins playing a crucial role in the dorsoventral patterning during embryonic development in the Drosophila melanogaster (D. melanogaster) almost 40 years ago. Subsequently, further research also showed a role of the Toll protein or Toll receptor in the recognition of Gram-positive bacterial and fungal pathogens infecting D. melanogaster. In 1997, the human homolog was reported and the receptor was named the Toll-like receptor 4 (TLR4) that recognizes lipopolysaccharide (LPS) of the Gram-negative bacteria as a pathogen-associated molecular pattern (PAMP). Identification of TLR4 in humans filled the long existing gap in the field of infection and immunity, addressing the mystery surrounding the recognition of foreign pathogens/microbes by the immune system. It is now known that mammals (mice and humans) express 13 different TLRs that are expressed on the outer cell membrane or intracellularly, and which recognize different PAMPs or microbe-associated molecular patterns (MAMPs) and death/damage-associated molecular patterns (DAMPs) to initiate the protective immune response. However, their dysregulation generates profound and prolonged pro-inflammatory immune responses responsible for different inflammatory and immune-mediated diseases. This chapter provides an overview of TLRs in the control of the immune response, their association with different diseases, including TLR single nucleotide polymorphisms (SNPs), interactions with microRNAs (miRs), use in drug development and vaccine design, and expansion in neurosciences to include pain, addiction, metabolism, reproduction, and wound healing.