Dipeptidyl peptidase 4 (DPP4) in fecal samples: validation of the extraction methodology and stability in short-term storage conditions

Autores da FMUP

• Francisco Jorge Nunes De Melo

  Autor

• Claudia Camila Rodrigues Pereira Dias

  Autor

• Fernando José Magro Dias

  Autor

Participantes de fora da FMUP

• Gomes, SF
• Silva, R
• Santiago, M
• Estevinho, MM
• Dias, S

Unidades de investigação

• Biomedicina

• Laboratório Associado RISE- Rede de Investigação em Saúde

  

  Investigador

  Fernando Carlos De Landér Schmitt

• Recursos Comuns

  

  Investigador

  Guilhermina Maria Da Silva Rêgo

• RISE-Health

  

  Investigador

  Fernando Carlos De Landér Schmitt

Abstract

Objectives This study assesses the clinical relevance of dipeptidyl peptidase 4 (DPP4) membrane exopeptidase as a biomarker of inflammatory bowel disease (IBD). A spike-and-recovery approach of DPP4 in fecal samples was used to compare two different methods for protein extraction, followed by a stability assessment. Methods Fecal samples of healthy volunteers spiked with known concentrations of recombinant DPP4 were processed using a standard manual extraction protocol and the CALEX((R)) protocol. The two methods were compared by quantification of fecal DPP4 by ELISA, followed by Bland-Altman analysis. For the stability assays DPP4 was extracted from fecal samples and stored under different conditions of temperature and time after collection. Results In general, the levels of spiked DPP4 in stool samples were lower with the manual protocol than in those obtained with the CALEX((R)) method; this trend was corroborated by Bland-Altman analysis. Nonetheless, variability was within the acceptable limits for both protocols. In the stability assessment, no statistically significant differences were found between the results obtained under the different storage conditions. Conclusions Both manual and CALEX((R)) protocols provided equal extraction ability of DPP4 from stool samples. In addition, DPP4 provided flexibility in terms of sample storage enabling the accurate assessment of samples delivered up to a week before analysis.

Keywords

• dipeptidyl peptidase 4; extraction; fecal samples; inflammatory bowel disease; stability