Association Between Pattern Recognition Receptors Gene Single Nucleotide Polymorphisms And The Susceptibility To Cryptococcal Meningitis

Background and objectiveCryptococcal meningitis(CM)is the most common fungal infectious disease of the central nervous system(CNS).CM can occur in immunocompromised patients,including human immunodeficiency virus(HIV)infected patients,and patients receiving long-term glucocorticoid or immunosuppressant treatment,as well as immunocompetent populations.In European and the American countries,most CM patients have underlying disease causing immunodificiency;in China,CM patients are predominantly immunocompetent people without underlying disease,accounting for 50%-77%.The so-called "immunocompetent" patients may have an underlying immunogenetic defect.Pattern recognition receptors(PRRs)are widely presented on the surface of innate immune cells and initiate the innate immune response by recognizing pathogen-associated molecular patterns(PAMPs),among which Toll-like receptors(TLSs)and C-type lectin receptors(CLRs)are involved in the recognition of cryptococci.The relationship between their genetic polymorphisms and CM susceptibility in Chinese population remains to be clarified.Materials and methodsImmunocompetent patients without underlying diseases diagnosed with CM at the People’s Hospital of Zhengzhou University from September 2020 to January 2022 were included,and their general information,clinical features,complications,ancillary examinations,complications,treatment and outcomes were recorded.Healthy subjects of the same period were included as controls.According to previous reports,PRR-related genes recognizing PAMP on the surface of cryptococcus were selected,including TLR1,TLR2,TLR4,TLR6,TLR9,mannose-binding lectin(MBL)2,dendritic cell associated C-type lectin(Dectin)1,Dectin2 and dendritic cell-specific ICAM-3-grabbing non-integrin(DC-SIGN)gene.19 single nucleotide polymorphism(SNP)loci of these genes which have significant effects on gene expression levels and protein structure and function were selected according to NCBI database.Peripheral blood leukocyte DNA was extracted from the subjects and SNP typing was performed for the above loci using multiple SNapShot typing technique.Hardy-Weinberg equilibrium(HWE)was performed,and those that met the HWE were subjected to the next step of analysis.Fisher’s exact probability test was used to compare the differences in genotype distribution between the case and control groups.Fisher’s exact probability test was used to compare the differences in allele and genotype distribution between the case and control groups.Logistic regression was used to analyze the potential association between SNP and susceptibility to CM.Results1.A total of 50 participants were included in this study,including 24 CM patients and 26 controls.2.Multiple SnapShot sequencing revealed rs5743563 and rs5743604 of TLR1 gene,rs3804099 of TLR2 gene,rs3796508 of TLR6 gene,rs352140 of TLR9 gene rs2306894 and rs3901533 of Dectin-1 gene,rs11045418 of Dectin-2 gene,rs4804800 and rs7252229 of DC-SIGN gene and rs7096206,rs7095891 and rs1800450 of MBL2 gene were polymorphic.The genotype distribution of the SNP loci in the control group was consistent with HWE(P>0.05),indicating that the genotype frequencies of each locus in the study population were in equilibrium and representative of the population.3.Comparison of genotype and allele frequency distribution between CM patients and controls revealed that the frequencies of GG,GA and AA at rs5743604 locus in the case group were 16.67%,45.83%and 37.50%,respectively,and the frequencies of GG,GA and AA in the control group were 19.23%,30.77%and 11.54%,respectively,and the difference in AA genotype frequency distribution was statistically significant(P<0.05),suggesting that the AA genotype at rs5743604 locus was a susceptibility gene for CM.The differences in genotype frequency and allele frequency distribution of the other loci were not statistically significant.4.Logistic regression analysis suggested that under the dominant model,genotypes GG and GA at the rs5743604 locus reduced the risk of CM compared with genotype AA(OR=0.22,95%CI:0.05-0.94,P<0.05),and genotype AA increased the risk of CM.Conclusion1.SNP of rs5743604 in TLR1 gene was associated with CM susceptibility.In the absence of immunocompromised underlying diseases,people with AA genotype rs5743064 locus were relatively susceptible to CM.2.SNP of TLR2,TLR6,TLR9,Dectin-1,Dectin-2,DC-SIGN and MBL2 gene SNP had no clear correlation with CM susceptibility.3.SNP at rs5743064 may serve as a genetic susceptibility marker as a potential target for future development of early diagnostic,predictive and individualized treatment tools.