Structure/epitope analysis and IgE binding activities of three cyclophilin family proteins from Dermatophagoides pteronyssinus

Cyclophilins (CyPs) are involved in basic cellular functions and a wide variety of pathophysiological processes. Many CyPs have been identified as the aetiological agent and influence on the immune system. In the present study, the physicochemical and immunologic characteristics of three proteins of CyPs family (CyPA, CyPB and CyPE) were analyzed. The results indicated that CyPE showed a closer evolutionary relationship with allergenic CyPA. The structure and antigenicity of CyPE was significantly similar with CyPA. B-cell epitopes of CyPE and CyPA were predicted via multiple immunoinformatics tools. Three consensus B-cell epitopes of CyPE and CyPAs were finally determined. To verify results of in silico analysis, three proteins of CyPs family (CyPA, CyPE and CyPB) were cloned and expressed from Dermatophagoides pteronyssinus. ELISA results indicated that the positive reaction rates of the three proteins to patient serum are CyPA (21.4%), CyPE (7.1%), and CyPB (0%), illustrating that the IgE activity was exhibited in CypA and CypE excluding CyPB. Structure and immunoinformatics analysis demonstrated that the RNA-binding motif of CyPE could reduce the immunogenicity of PPIase domain of CyPE. The reason that CyPB has no IgE activity might be the structure mutation of CyPB on B-cell epitopes.