Correlation between Toll-like Receptor Gene Polymorphisms and Idiopathic Nephrotic Syndrome in Chinese Children

OBJECTIVE

Idiopathic nephrotic syndrome (INS) is the most common glomerular disease in children. Toll-like receptors (TLRs) have been reported to be associated with response to steroid treatment in children with INS. Nevertheless, the correlation between TLR genes and the progression of INS has not yet been clarified. The present study aimed to investigate the association of single-nucleotide polymorphisms (SNPs) in TLR2, TLR4, and TLR9 with susceptibility to INS as well as the clinical phenotyping of steroid responsiveness in Chinese children with INS.

METHODS

A total of 183 pediatric inpatients with INS were included and given standard steroid therapy. Based on their clinical response to steroids, the patients were classified into three groups: steroid-sensitive nephrotic syndrome (SSNS), steroid-dependent nephrotic syndrome (SDNS), and steroid-resistant nephrotic syndrome (SRNS). A total of 100 healthy children were employed as controls. The blood genome DNA was extracted from each participant. Six SNPs (rs11536889, rs1927914, rs7869402, rs11536891, rs352140, and rs3804099) in TLR2, TLR4, and TLR9 were selected and detected by multiplex polymerase chain reaction with next-generation sequencing to assess TLR gene polymorphisms.

RESULTS

Among the 183 patients with INS, 89 (48.6%) had SSNS, 73 (39.9%) had SDNS, and 21 (11.5%) had SRNS. No significant difference was found in the genotype distribution between healthy children and patients with INS. However, the genotype and allele frequencies of TLR4 rs7869402 were significantly different between SRNS and SSNS. Compared with patients with the C allele and CC genotype, patients with the T allele and CT genotype had an increased risk of SRNS.

CONCLUSION

TLR4 rs7869402 affected the steroid response in Chinese children with INS. It might be a predictor for the early detection of SRNS in this population.

Gene duplication and adaptive evolution of Toll-like receptor genes in birds

Toll-like receptors (TLRs) play an important role in innate immune through recognizes pathogens. In order to reveal the evolutionary patterns and adaptive evolution of avian TLRs, we examined 66 representative bird species in 26 orders. Phylogenetic results indicated that TLR1A and TLR1B may have differentiated functionally. Evolutionary analysis showed that the TLR genes in birds under strong Purification selection (0.165-0.4265). A total of 126 common positively selected codons were identified in 10 TLR genes of avian, and most sites were located in the extracellular leucine-rich repeat (LRR) functional domains, and both environment and feeding habits were external factors driving the evolution of avian TLR genes. Environmental pressures had a greater effect on TLR1B, TLR2B, TLR3 and TLR4, while feeding habits were active in affecting TLR2A, TLR2B, TLR15 and TLR21. Our data suggested that TLR genes have been subjected to different selective pressures in the diversification of birds and that these changes enabled them to respond differently to pathogens from diverse sources.

Single-nucleotide polymorphism-based genetic diversity analysis of the Kilakarsal and Vembur sheep breeds

AIM

The present study was thus undertaken to analyze the genetic diversity of Kilakarsal and Vembur sheep breeds using single-nucleotide polymorphism (SNP) markers within Toll-like receptor (TLR) 3, 5, 6, 9, and 10 genes.

MATERIALS AND METHODS

Competitive allele-specific polymerase chain reaction (PCR)-based end-point genotyping was performed using real-time PCR to type the SNPs. Allele discrimination module implemented in real-time PCR was utilized to call the genotypes based on fluorescence intensity recorded for each of the two alleles. Basic diversity indices, namely, gene frequencies, observed heterozygosity, expected heterozygosity, and inbreeding coefficient (F_IS), and testing for Hardy-Weinberg equilibrium (HWE) were estimated using package for elementary analysis of SNP data software program.

RESULTS

Of the 25 SNPs, 22 were found to be polymorphic, whereas two SNPs, namely, TLR3_1081_AC and TLR9_2036_CT, were monomorphic in both Kilakarsal and Vembur sheep populations. The SNP TLR10_1180_AG was monomorphic in Kilakarsal but polymorphic in Vembur sheep. The observed heterozygosities were estimated as 0.289 and 0.309 in Kilakarsal and Vembur sheep, respectively, whereas the expected heterozygosity values were 0.305 and 0.309 in the two breeds, respectively. The overall mean F_IS was 0.107 ranging from -0.005 to 0.241 in Kilakarsal sheep and -0.047 ranging from -0.005 to 0.255 in Vembur sheep. In Kilakarsal sheep, the test for HWE revealed TLR9_1308_GC SNP locus with significant deviation (p<0.05) due to heterozygosity deficit. In Vembur sheep, TLR10_82_CT and TLR10_292_CG loci showed significant deviation (p<0.05) due to heterozygosity excess. Other SNP loci did not deviate from HWE (p>0.05) revealing that the population was in HWE proportions.

CONCLUSIONS

The SNP markers within five TLR genes (TLR3, TLR5, TLR6, TLR9, and TLR10) utilized for genotyping in this study were highly polymorphic in Kilakarsal and Vembur breeds of sheep. This study on the genetic diversity analysis of the Kilakarsal and Vembur sheep breeds revealed considerable genetic variation within the breeds and it can be utilized to improve desirable traits.