Development And Clinical Validation Of A Serum REG Ⅰα In-Vitro Diagnostic Kit For Screening Of Organic Gastrointestinal Disorders

BACKGROUND AND POURPOSE:It’s difficult to distinguish between organic gastrointestinal disorders(OGIDs)and functional gastrointestinal disorders(FGIDs)in clinical practice and lack noninvasive means of identification.Gastrointestinal mucosal injury and epithelial inflammation are the differences between them.Regenerating islet-derived protein 1-alpha(REG Ⅰα)is involved in the healing process of mucosal injury and inhibition of epithelial inflammation of various OGIDs,granting it the potential as a biomarker for OGIDs diagnostics.However,most studies remain at the animal/human tissue level,and whether serum REG Ⅰα is also elevated and has screening value for OGIDs remains unclear.Here we developed a serum REG Ⅰα in-vitro diagnostic kit for clinical use in accordance with the standard of in-vitro diagnostics(IVD),and verified its screening value for OGIDs.METHODS:Recombinant REG Ⅰα protein was obtained by transfection of plasmid into eukaryotic 293 suspension cells for expression,secretion and purification.Serum REG Ⅰα IVD kit was prepared by a pair of mouse monoclonal antibodies for clinical detection.309 normal controls(NCs),136 FGIDs subjects and 372 OGIDs subjects were included in a cross-sectional study investigate the difference of serum REGⅠα in different population sera and explore its screening efficacy for OGIDs.Meanwhile,it was compared with C-reactive protein(CRP).The receiver operating characteristic curve(ROC)and chi-square test were used to evaluate the diagnostic value.The cutoff value of serum REG Ⅰα concentration was defined as 60.0 ng/mL.RESULTS:The development process and results of in-vitro diagnostic kit are in accord with IVD standard.A total of 817 serum samples were collected from 817 subjects.Serum concentrations of REG Ⅰα progressively increased in NCs,FGIDs and OGIDs(P<0.0001).The median serum REG Iαlevel of all OGIDs subjects was higher than that of NCs(P<0.0001),and the median serum REG Ⅰα level of all OGIDs subjects except the adenomatous polyp(P=0.274)was higher than that of FGIDs(P<0.05).Subjects with serum REG Ⅰα ≥60.0 ng/mL accounted for 14%of NCs,21%of NOGIDs(NCs+FGIDs),38%of FGIDs,and 67%of OGIDs.The area under curve(AUC)of serum REG Ⅰα reached 0.872,0.822 and 0.710 in the NCs and OGIDs groups,NOGIDs and OGIDs groups,FGIDs and OGIDs groups,respectively.In subjects who tested serum REG Ⅰα and CRP together,the REG Ⅰα had a higher AUC value(0.711)than the CRP(0.687),and the AUC value of the combination of REG Ⅰα and CRP was higher(0.766).CONCLUSIONS:We developed a mouse monoclonal antibody serum REG Ⅰαin-vitro diagnostic kit based on enzyme linked immunosorbent assay can provide good uniformity and small error detection means for related clinical studies.Serum REG Ⅰα can be used as a new noninvasive serological marker for the screening of OGIDs,and can assist in the clinical screening of patients who need to improve the invasive examination such as gastroenteroscopy to confirm the diagnosis.Moreover,its diagnostic efficacy is better than CRP,and it has higher gastrointestinal specificity.The combined diagnosis of the two indexes is superior to the diagnosis of single index.