Analysis Of HLA-B27 Gene Polymorphism And Bone Metabolism In Patients With Ankylosing Spondylitis

Background:Ankylosing spondylitis(AS)is a chronic progressive rheumatic disease.In which the central and peripheral joints are mainly involved and is common in young men.The main clinical manifestations are inflammatory lesions of the ankle joint and spinal attachment point.Leading to joint dysfunction and even loss of function,which seriously affects the quality of patients' life.Studies have showed that Gene HLA-B27 has a strong correlation with AS.The positive rate of HLA-B27 in AS patients could be as high as 90%,which is significantly higher than that in healthy people.AS is characterized by the formation of chronic inflammation centering on the bone attachment points of the joint capsule,tendon,and ligament in the central and peripheral joints,which bring about bone erosion,cartilage destruction and tissue fibrosis and ossification,ultimately destroying the entire ligament.Therefore,AS has obvious pathological osteogenesis,and the ossification of the spine and joints is the main cause of disability in AS patients.Although it is a pathogenic osteogenesis process,the possibility patients with AS get osteoporosis or osteopenia is still vary from 50% to 92%.Objective:The aim is to study human leukocyte surface antigen-B27(HLA-B27)and the distribution characteristics of HLA-B27 allele subtypes of AS patients in the Han population in Jiangxi,thus finding out the characteristics of genetic subtypes of AS patients in this area,and evaluating if HLA-B27 could be a diagnostic indictor.Studying the characteristics of non-HLA-B27 alleles paired with HLA-B27 in AS disease and analyzing the relationship between non-HLA-B27 alleles with AS disease.To study the characteristics of changes in bone metabolic markers in patients with AS,and to analyze the relationship between their level changes and AS diseases.Methods:Blood specimens were collected from 128 AS patients,76 RA patients,62 SLE patients and 50-health persons.Patients are from the Second Affiliated Hospital of Nanchang University from January 2016 to June 2018.In addition,50 healthy persons were chosen from the physical examination center of the hospital.Flow cytometry(FCM)was used to detect HLA-B27 antigen,and sequence-specific primer polymerase chain reaction(PCR-SSP)was used to detect HLA-B27 allele subtypes.The levels of bone metabolism markers were detected by chemiluminescence method,which contains osteocalcin(OC),parathyroid hormone(PTH),25-hydroxyvitamin D(25-(OH)D),total type I collagen amino terminal elongation peptide(TPINP),and beta-collagen specific sequence(?-CTX).Results:1.There are 316 subjects involved in this study,including 128 AS patients,76 RA patients,62 SLE patients and 50 healthy controls.The positive rate of HLA-B27 in the AS group is significantly higher than that in the control group(94.53% vs.3.33%).Additionally,the proportion of male was higher and the mean age was lower in the AS group.2.The specificity and sensitivity of the FCM method detecting HLA-B27 antigen to diagnose AS were 94.7% and 94.5% respectively,the positive predictive value and negative predictive value were 92.4% and 96.2%,respectively.while the specificity and sensitivity of PCR-SBT assay for detecting HLA-B27 gene were 96.3 % and 93.0% respectively,the positive predictive value and negative predictive value were 94.4% and 95.3%,respectively.3.HLA-B27 make up 94.53% of HLA-B allele in AS group,which was the highest and followed by HLA-B40,HLA-B15,HLA-B46 and HLA-B51 whose rate were 28.91% ?15.63%?14.06% and 9.38% respectively?There were four HLA-B27 subtypes detected-HLA-B2704,HLA-B2705,HLA-B2707 and HLA-B2715.The composition ratios of B2704,B2705,B2707 and B2715 were 87.40%,9.24%,2.52% and 0.84%,respectively.4.Compared with other paired allele genes of HLA-B27,HLA-B40 occupied the highest composition ratio,which is 29.06%,followed by HLA-B15 and HLA-B46 whose composition ratio was 13.68% and 11.97%,respectively.5.The average value of 25-hydroxyvitamin D in AS group was lower than that in RA,SLE and control group;and the average value of parathyroid hormone in AS group was lower than that in RA and SLE group.The levels of osteocalcin and ?-collagen in AS group were higher than those in RA,SLE and control group.Conclusion:1.HLA-B27 was the most common allele of AS patients in the han population in Jiangxi,followed by HLA-B40,HLA-B15,HLA-B46 and HLA-B51.Four HLA-B27 subtypes were detected in AS population,respectively HLA-B2704,HLA-B2705,HLA-B2707 and HLA-B2715,and HLA-B2704 was the main gene subtype.2.Detection of HLA-B27 gene and antigen has a relative high accuracy for AS diagnosis.3.Among the alleles paired with HLA-B27,the HLA-B40 allele is most common.4.The average value of 25-(OH)D and PTH in AS patients was lower than that in the control group,while the average value of OC and ?-CTX was higher.In addition,the bone metabolism of AS patients is abnormal.