Objective:To investigate the expression and clinical significance of decoy receptor 3 (DcR3) and its signal pathway-related molecules in PBMCs of patients with ankylosing spondylitis (AS).Methods:Peripheral blood samples, clinical data and laboratory test results were collected from 100 patients with ankylosing spondylitis [50 patients with AS activity (ASA), 50 patients with AS stability (ASS)], 30 patients with osteoarthritis and 30 patients with gouty arthritis (as disease control group), and 60 healthy controls (HC). The mRNA expression levels of DcR3 and its signal pathway related genes (DR3, TL1A, Fas, FasL, LIGHT, LIGHTR, LTβR) were measured by real-time fluorescence quantitative polymerase chain reaction. Measurement data among the three groups in normal distribution were analyzed by t test or one-way analysis of variance, pairwise comparisons using LSD- t test, non-normal distribution data were analyzed by Mann-Whitney test or Kruskal-Wallis H test, χ2 test was used for correlation analysis of categorical variables. Correlation analysis between variables were analyzed using Spearman correlation analysis. Results:① By comparing the AS group, disease control group and HC group, the expression levels of DcR3 mRNA and DR3 mRNA in the AS group were lower than those in disease control group and HC group, and DcR3 mRNA and DR3 mRNA in disease control group were lower than those in the HC group {DcR3mRNA: [6.21 (3.89, 10.70)]×10 -4vs [9.51 (5.89, 16.65)]×10 -4vs [17.81 (11.27, 24.20)]×10 -4, H=55.28, P<0.001; DR3 mRNA: [41.05 (24.09, 66.95)]×10 -4vs [58.28 (28.41, 94.38)]×10 -4vs [94.79 (54.07, 144.51)]×10 -4, H=37.10, P<0.001}. The expression level of TL1A mRNA in the AS group was higher than that in disease control group {[14.71(4.91, 42.22)]×10 -4vs [4.00(1.07, 16.60)]×10 -4vs [7.70 (3.52, 27.83)]×10 -4, H=17.71, P<0.001}; The expression level of Fas mRNA in AS group and disease control group was lower than that in HC group {[20.99(4.63, 62.89)]×10 -4vs [23.97(15.82, 38.99)]×10 -4vs [78.45 (27.32, 146.46)]×10 -4, H=31.17, P<0.001}. The expression level of FasL mRNA in AS group was higher than that in disease control group and HC group {[42.87(6.57, 91.21)]×10 -4vs [5.45(2.83, 10.32)]×10 -4vs [6.88 (4.57, 23.79)]×10 -4, H=46.42, P<0.001}. The expression level of LIGHTR mRNA in AS group was lower than that in disease control group {[52.66 (7.20, 143.21)]×10 -4vs [98.80 (53.11, 166.24)]×10 -4vs [63.47(40.85, 138.07)]×10 -4, H=11.96, P<0.001}. There were no significant differences in LIGHT mRNA and LTβR mRNA among all groups ( H=0.86, P>0.05; H=3.18, P>0.05). ②The expression levels of DcR3 mRNA, DR3 mRNA and Fas mRNA in ASA group and ASS group were lower than those in HC group. DcR3 mRNA in ASA group was higher than that in ASS group, and DR3 mRNA in ASA group was lower than that in ASS group {DcR3 mRNA: [7.28 (4.92, 16.56)]×10 -4vs [4.59 (2.49, 7.03)]×10 -4vs [17.81 (11.27, 24.20)]×10 -4, H=62.63, P<0.001; DR3 mRNA: [30.93(16.18, 66.66)]×10 -4vs [47.17(29.91, 67.40)]×10 -4vs [94.79(54.07, 144.51)]×10 -4, H=41.48, P<0.001; Fas mRNA: [20.04(3.29, 62.30)]×10 -4vs [22.49(5.63, 64.79)]×10 -4vs [78.45(27.32, 146.46)]×10 -4, H=23.54, P<0.001}. The expression levels of TL1A mRNA and LTβR mRNA in the ASA group were higher than those in the ASS group and the HC group {TL1A mRNA: [32.36(10.09, 97.84)]×10 -4vs [9.98(1.29, 21.63)]×10 -4vs [7.70(3.52,27.83)]×10 -4, H=21.14, P<0.001; LTβR mRNA: [6.13(2.16,20.06)×10 -4vs [2.13(0.53,8.04)]×10 -4vs [2.72 (1.24,5.73)]×10 -4, H=12.86, P<0.001}. The expression level of FasL mRNA in the ASA group and the ASS group was higher than that in the HC group {[60.70 (8.16, 106.16)]×10 -4vs [30.14 (5.37, 78.40)]×10 -4vs [6.88 (4.57, 23.79)]×10 -4, H=18.99, P<0.001}. The expression level of LIGHTR mRNA in ASS group was lower than that in HC group {[49.79(10.75, 168.48)]×10 -4vs [15.92(3.27, 105.91)]×10 -4vs [63.47(40.85, 138.07)]×10 -4, H=11.80, P<0.001]. There was no significant difference in LIGHT mRNA among all groups ( H=4.15, P>0.05). ③Spearman correlation analysis showed that DcR3 level was positively correlated with BASDAI score and hsCRP in AS patients ( r=0.52, P<0.001; r=0.35, P<0.01), and DR3 level was negatively correlated with BASDAI score, ESR and hsCRP level ( r=-0.28, P<0.001; r=-0.25, P<0.001; r=-0.31, P<0.001). TL1A was positively correlated with BASDAI score, ESR and hsCRP level ( r=0.23, P=0.046; r=0.26, P=0.015; r=0.25, P=0.017). Conclusion:DcR3 and its signal pathway-related molecules are differentially expressed in PBMCs of patients with AS, suggesting that they may participate in the occurrence and development of AS.

AIM:This study aims to investigate the histopathological and ultrastructural alterations in the lung tissues of rats induced by a single intratracheal administration of bleomycin,with the objective of establishing a reliable model for future applications.METHODS:Six to eight-week-old SD rats were randomly allocated into two groups:the control group and the model group(n=12).Pulmonary fibrosis was induced in the rat models by a single intratracheal in-stillation of bleomycin(3 mg/kg),while an equivalent volume of saline was administered to the control group.The rats were executed on the 42nd day.Twelve rats remained in the control group,while nine rats remained in the model group.Lung tissue imaging was conducted using CT scans.Lung function tests were performed to assess changes in forced vital capacity(FVC)and dynamic lung compliance(Cdyn).Lung stiffness was determined through Young's modulus testing using a rheometer.The pathological structure of lung tissues was examined using both HE and Masson staining methods.Additionally,transmission electron microscopy was employed to evaluate collagen deposition in lung tissues,alveolar type Ⅱ epithelial cells,macrophages,and ultrastructural changes of the respiratory membrane.RESULTS:CT scans revealed honeycomb patterns in the lungs of model rats,along with partial bronchiectasis/bronchiectasis.In comparison to the con-trol group,the model group exhibited significantly lower FVC and Cdyn values,while lung stiffness were increased.HE and Masson staining demonstrated that rats in the model group exhibited alveolar structure destruction,alveolar septum thickening,inflammatory cell infiltration,and collagen deposition in alveolar septum.Transmission electron microscopy revealed several abnormalities in the model group:increased collagen fibers in the alveolar septa,misalignment of micro-villi in alveolar type Ⅱ epithelial cells,wrinkled nuclei with increased heterochromatin,swollen cytoplasmic mitochon-dria,fractured or haphazardly structured mitochondrion cristaes,and a significant decrease in their number(P＜0.05).Furthermore,lamellar bodies were vacuolated and reduced in number(P＜0.05),and dilated endoplasmic reticulums with degranulation were observed.There was an increase in alveolar macrophages and interstitial macrophages(P＜0.01).The respiratory membrane displayed structural disruptions and an increase in thickness(P＜0.01).CONCLUSION:Bleomycin induces decreased lung compliance,alveolar epithelial injury,alveolar septum thickening,collagen deposi-tion,and an increase in interstitial macrophages,ultimately resulting in pulmonary fibrosis in rats.