Research Among Systemic Sclerosis With Pulmonary Interstitial Fibrosis Serum Markers

BackgroundSystemic sclerosis (SSc) is a connective tissue disease characterized by sclerotic changes in the skin and internal organs. Interstitial lung disease (ILD) develops in more than50%of SSc patients and is the major cause of death. Now there is no generally accepted clinical serum marker for SSc patients with ILD. In recent years, there are some reports on the IPF suggested that the level of some biomarkers in serum, plasma or BALF, such as KL-6, SP-A, SP-D, CCL18and CXCL12was significantly higher in IPF patients. Easier, less-invasive, and lung-specific serologic markers would be helpful for closely monitoring the activity of ILD in SSc patients.Objective and methodsTo define the potential roles of KL-6, SP-A, SP-D, CCL18, CXCL12as serum biomarkers for SSc-ILD by detecting its plasm level through ELISA and comparing it between SSc-ILD and SSc-non ILD patients.Results1、Plasm levels of SP-D, CXCL12in SSc-ILD patients were significantly higher than SSc-non ILD patients (P<0.05). Diagnosis critical point of SP-D is14.23ng/ml (sensitivity85.7%, specificity33.8%). Diagnosis critical point of CXCL12is1.81ng/ml (sensitivity61.3%, specificity69.3%). Plasm level of SP-A in SSc-ILD patients was significantly lower than SSc-non ILD patients (P<0.05). Plasm levels of KL-6, CCL18between these two groups showed no significant difference (P>0.05).2、Plasm level of SP-A in SSc patients with cough or short breath was significantly lower than those without cough and short breath (P<0.05). Plasma levels of CCL18and CXCL12in SSc patients with dysonea were significantly higher than those without dyspnea (P<0.05).3、Plasm level of SP-D in SSc patients was negatively correlated with TLC%, and CXCL12was negatively correlated with TLC%, FEV1, DLCO and DLCO% (R<-0.200,P<0.005).4、Plasm level of KL-6, SP-D, CXCL12in SSc patients were positive correlated with interlobular septal thickening on HRCT. Plasm level of CCL18was negative correlated with reticular opacities (R<-0.200, P<0.005).Conclusions1、High plasm levels of KL-6, SP-D and CXCL12in SSc patients may be combined ILD, which may indicate the occurrence of early ILD2、Activity stage in SSc patients with ILD may occur when levels of plasma CCL18elevated.3、Advanced stage in SSc patients with ILD may occur when plasma levels of SP-A decreased.