Volunteer study and serum protein profiling to understand inflammatory response induced by Satsuma mandarin

It has been observed that consumption of a certain amount of Satsuma, lychee, and longan often caused a symptom characterized by dry or sore throat, gum swelling and even mouth ulcer, which significantly impaired the life quality of a large population. We define the adverse reaction to Satsuma as Satsuma-induced syndrome (SIS). Volunteers were assigned to oral Satsuma challenge in an open manner. The results showed that SIS was characterized with symptoms affecting the throat, oral cavity, face, gastrointestinal system and eye either individually or in combination. A comparative proteomic study was performed to investigate the differences of serum proteins in the Post-SC (after Satsuma challenge) and Pre-SC (before Satsuma challenge) serum samples of 15 volunteers with severe SIS. Ten proteins were identified to be differentially expressed (P<0.05). Of these, levels of complement component C9 precursor were elevated significantly in the Post-SC serum samples and were further verified by enzyme-linked immunosorbent assay, indicating that the complement system may be activated and plays a significant role in inflammatory response. Meanwhile, serum samples were subjected to immobilized metal affinity capture (IMAC3) protein chip surfaces and tested by surface-enhanced laser desorption/ionization-time of flight-mass spectrometry. The data were analyzed by Ciphergen ProteinChip Software. A diagnostic model was constructed to discriminate the SIS from normal samples, using principal component analysis. A total of 50 detected biomarkers were found to be different with statistical significance (P<0.05). The multivariate logistic analysis demonstrates a complete distinction between the two groups. Our findings suggest that these assays may provide potential biomarkers for the diagnosis of SIS.