Study On The Relationship Between Serum IL-38 And Axial Spondyloarthritis

Objective: By detecting the expression of serum interleukin 38(IL-38)and related cytokines in axial spondyloarthritis(ax-SpA)before and after treatment,analyzing the correlation with ax-SpA serological and clinical indicators,and to explore the clinical significance of IL-38 and related cytokines in ax-SpA.Methods: The newly diagnosed patients included in the Rheumatology Department of The Affiliated Hospital of Guilin Medical University from July2021 to December 2022 were ax-SpA group(n=33),and received TNF-αinhibitor adalimumab as ax-SpA treatment group(n=30),the ax-SpA group was divided into different subgroups according to disease activity and bone mineral density.The healthy people in the physical examination center of our hospital were selected as the control group(n=30).Collecting blood samples and clinical data,including sex,age,BASDAI,morning stiffness time,PLT,globulin,blood calcium,immunoglobulin(Ig M,Ig A,Ig G),complement(C3,C4),C-reactive protein(CRP),erythrocyte sedimentation rate(ESR),T cell subsets,lymphocyte subsets,bone metabolism index,bone mineral density,sacroiliac joint plain film,sacroiliac joint MRI,etc.ELISA was used to detect the expression of serum IL-38,IL-6,IL-17,IL-37 and TNF-α.For normal distribution data,two independent samples were compared by independent sample t-test,paired sample t-test was used to compare before and after treatment,and Pearson was used for correlation analysis;non-normal distribution data,two independent samples were compared by Mann-Whitney U test,Wilcoxons-rank test was used to compare before and after treatment,and Spearman was used for correlation analysis.Results:(1)Compared with the control group,the level of IL-38 in ax-SpA group was low,and increased after treatment,while the levels of IL-6,IL-17,IL-37 and TNF-α were high,and decreased after treatment,the difference was statistically significant(P<0.001).(2)The levels of C3,ESR,CRP,BASDAI and the scores of sacroiliac arthritis in ax-SpA group increased and decreased after treatment,and the difference was statistically significant(P<0.001).(3)In ax-SpA group,the duration of morning stiffness was longer,and the levels of serum calcium,BMD,Z/T value decreased and increased after treatment(P<0.05),but there was no significant difference in Ig M,Ig A,Ig G,C4,bone metabolism index,T cell subsets and lymphocyte subsets before and after treatment.(4)Compared with the low disease activity group,the expression of IL-38 in the high disease activity group was lower,while the expression of IL-6,IL-17,IL-37,TNF-α,C3,ESR,CRP and BASDAI were significantly higher than that in the low disease activity group(P<0.001).There was no significant difference in Ig M,Ig A,Ig G,C4,serum calcium,bone metabolism index,T cell subsets,lymphocyte subsets,BMD,Z/T value and sacroiliac arthritis score.(5)There were no significant difference in the levels of cytokines,serology and clinical indexes between non-osteoporotic group and osteoporotic group(P>0.05).(6)IL-38 was negatively correlated with IL-6,IL-17,IL-37,TNF-α,C3,ESR,CRP and BASDAI in ax-SpA group,and the differences were statistically significant(P<0.05),but not with Ig M,Ig G,C4,serum calcium,bone metabolism index,T cell subsets,lymphocyte subsets,serum calcium,BMD,Z/T value,sacroiliac arthritis score and morning stiffness time(P>0.05).(7)IL-6、IL-17、IL-37、TNF-αwere positively correlated with C3、ESR、CRP、BASDAI,while IL-6 was negatively correlated with BMD(P<0.05).Conclusions:(1)The expression of serum IL-38 in ax-SpA was low and increased after treatment,The imbalance between the expression of IL-38 and cytokines may be involved in the immune inflammatory response of ax-SpA.(2)TNF-alpha inhibitors can up-regulate the level of IL-38,down-regulate the levels of IL-6,IL-17,IL-37 and TNF-α,and control disease activity.IL-38 and related cytokines can be used as one of the indicators to monitor the disease activity of ax-SpA.