The Clinical Value Of Exploring The Activation Of Neutrophil Extracellular Traps In Ankylosing Spondylitis

Objective Ankylosing spondylitis(AS)is a common immune-mediated inflammatory arthritis with strong genetic susceptibility.Its main symptoms are chronic inflammation of sacroiliac joints and spinal attachment points,including joint surface sclerosis,erosion,bone remodeling and ankylosis of sacroiliac joints,which may also be accompanied by non-joint changes.Current research shows that the activation of neutrophils and the formation of neutrophil extracellular traps(NETs)may be involved in the occurrence and development of autoinflammatory diseases.One study on the serum of five patients with AS shows that the expression of NETs is different from that of normal people,but there is no report on whether NETs participate in the pathogenesis of Chinese patients with AS.This study confirmed the increased expression of NETs in patients with AS and discussed its clinical significance.Methods This study collected 22 patients with AS who were hospitalized and diagnosed in the Department of Rheumatology and Immunology of the Affiliated Hospital of Nantong University from September 2021 to September 2022,and selected22 normal individuals matched with the AS patient group in terms of age,sex,and other aspects without basic diseases as the control group,collected the basic characteristics,relevant physiological and biochemical indicators of the group.The patients were investigated by using Bath Ankylosing Spondylitis Disease Activity Index(BASDAI),Bath Ankylosing Spondylitis Functional Index(BASFI),Bath Ankylosing Spondylitis Metrology Index(BASMI),the 10-cm Visual Analog Scale(VAS),the Health Assessment Questionnaire-Disability Index(HAQ),the Hospital Anxiety and Depression Scale(HADS),and the Fatigue Severity Scale(FSS).In this study,blood samples from patients and healthy control groups were collected to isolate neutrophils,and the levels of myeloperoxidase(MPO)in spontaneous NETs formation and in vitro stimulated NETs formation of neutrophils were detected by enzyme-linked immunosorbent assay(ELISA),and their correlation with disease activity and laboratory indicators was studied;The formation of NETs was qualitatively analyzed by immunofluorescence staining;Western blot(WB)was used to quantitatively detect the level of NETs marker protein in the healthy control group and AS patients.In this study,the Kolmogorov-Smirnov test,independent sample t-test,Mann-Whitney U test,chi-square test,Pearson/Spearman correlation analysis,and other statistical methods were used to analyze the data.Results Twenty-two patients with AS were finally included in this study,including 15(68.18%)males with an average age of 40 years.The average score of BASDAI was 0.8,and the average value of BMI was 22.1 ± 1.933kg/m~2.Among 22 healthy controls.Twenty-two healthy controls were finally included in this study,including 13(59.1%) males with an average age of 42 years,and the average BMI was 22.3 ± 1.87kg/m~2.The results showed that the formation of NETs in the AS patients group was stronger than that in the healthy control group under an upright fluorescent microscope,and the active phase of the disease was higher than that in the stable phase.The results of ELISA showed that the concentration of MPO of blood plasma in the AS patients group was[159.85(103.32 194.99)] pg/ml and(78.54 ± 18.696)pg/ml respectively,compared with the healthy control group,P<0.01,the difference was statistically significant;The concentration of MPO in the supernatant after PMA stimulation and culture in vitro was(87.93 ± 17.007)pg/ml and(60.01 ± 11.687)pg/ml respectively,P<0.01,the difference was statistically significant.Western Blot results are consistent with the above experimental results.The formation of spontaneous NETs in patients with AS was correlated with age,disease duration,BMI,education level,work,and uric acid,and was positively correlated with BASDAI.The formation of NETs stimulated in vitro was correlated with BASMI,white blood cell count,platelet count,and creatinine,and had no statistical significance with HLA-B27,ESR,and CRP.Conclusions This study has shown that the formation of NETs in neutrophils in the peripheral blood of AS patients is increased,and its expression has a strong correlation with the course of the disease,BMI,BASDAI,BASMI,etc.,indicating that NETs expression is related to the disease activity of AS patients.This study provides a potential theoretical basis for NETs as biological markers of AS to reflect the disease status of patients,prompt the prognosis,and guide the individualized treatment of doctors.