Abstract
Introduction
Inflammatory bowel disease (IBD) consists of two distinct disorders, Crohn’s disease (CD) and ulcerative colitis (UC). The best way to assess IBD disease activity is a colonoscopy. The non- invasive biomarkers faecal myeloperoxidase (fMPO) and faecal calprotectin (fCal) are proven to be accurate at reflecting IBD disease activity. However, limited studies have investigated plasma biomarkers in relation to IBD disease activity. This thesis aims to investigate plasma myeloperoxidase (pMPO) and calprotectin (pCal) as markers of endoscopic activity in IBD.
Methods
Prospectively recruited participants with IBD undergoing colonoscopy for disease assessment provided biological samples prior to colonoscopy.
Enzyme-linked immunosorbent assay (ELISA) kits were used to measure pCal and pMPO.
The Mann-Whitney U test compared pMPO and pCal concentrations between active and inactive disease. Spearmen rank correlation was used to correlate plasma biomarkers with faecal biomarkers, endoscopic indices and patient reported symptom scores.
Area-under the receiver operating characteristics curve (AUROC) and univariable logistic regression were used to assess the utility of plasma biomarkers in predicting active IBD.
Results
170 participants were included (92 female, 99 CD). pCal and pMPO concentrations were significantly associated with endoscopic scores in both CD and UC (SES-CD (rpCal=0.33, p<0.01; rpMPO=0.23, p<0.05) and UCEIS (rpCal=0.37, p<0.01; rpMPO=0.47, p<0.001)). pCal was significantly associated with fCal in CD (r=0.28, p<0.01) and UC (r=0.25, p=0.04). pMPO was significantly associated with fMPO in UC (r=0.35, p<0.01) but not CD (r=0.16, p=0.11). Median pCal (1286.06 ng/ml vs. 975.05 ng/ml, p<0.05) and pMPO (16.38 ng/ml vs 9.73 ng/ml, p<0.01) were significantly higher in active versus inactive UC but not CD (p>0.05). Plasma biomarkers more accurately predicted active UC (AUROCpCal=0.66, p=0.02; AUROCpMPO=0.76, p<0.001) than CD (AUROCpCal=0.65, p=0.02; AUROCpMPO=0.62, p=0.07). pMPO >13 ng/ml (odds ratio (OR)=3.33, 1.67-6.60) and pCal >1043 ng/ml (OR=2, 1.03-3.9) were associated with an increased risk of endoscopically active disease.
Conclusions
pMPO and pCal are promising biomarkers of IBD activity, especially in UC. pMPO had superior performance at predicting active UC compared with pCal. Plasma biomarkers should be further examined for their use in monitoring treatment response and predicting long term complications.