Quantifying Fecal Tumor Necrosis Factor-α (TNF-α) in Active IBD Compared to Other Forms of Enterocolitis: A Prospective Study

Abstract

Introduction: The ability to utilize inflammatory markers in inflammatory bowl disease (IBD) for diagnosis, disease activity and prognosis is an active area of ongoing research. Markers such as neutrophil gelatinase-associated lipocalin, calprotectin, interleukin-8 and TNF-α have been studied in the stool samples of IBD patients. Identifying a more sensitive and specific marker to detect and monitor progression of disease could provide a less invasive and more feasible tool in management of patient care. Specifically, TNF-α in stool samples has been shown to be elevated in acute flares of IBD compared to other causes of diarrhea. To date, there have been limited studies conducted in adults comparing levels of TNF-α in stool samples from patients with acute IBD flares verses other causes of enterocolitis. Studies in children have revealed statistically significant differences in stool TNF-α levels in patients with IBD compared to infectious causes. Aim: To analyze levels of TNF-α and calprotectin in stool specimens between two cohorts of patients to assess the accuracy of these cytokine markers in differentiating between IBD and other inflammatory conditions of the GI tract. Methods: Subjects fulfilling the diagnostic criteria for ulcerative colitis (UC) and Crohn’s disease who were symptomatic and others with symptomatic enterocolitis were recruited from both the outpatient GI clinic and in-patient hospital. Subjects were identified if diagnosed as having symptomatic colitis or flare of IBD identified by stool cultures, signs and symptoms, or endoscopy/histology reports revealing gastrointestinal inflammation. After obtaining informed consent, subjects were enrolled in the study and stool samples were collected and stored in -80 C freezer. Samples were then processed and ran to determine levels of TNF-α and calprotectin via ELISA. Results: Seventy-four stool samples were collected from adults comprising of 22 CD, 19 UC and 33 other colitides including C. dificile, Salmonella, Shigella, diverticular colitis, ischemic colitis, microscopic colitis and indeterminate colitis. TNF-α levels were found in only 6 fecal samples; 3 CD with mean 0.63 pg/mL, 2 UC with mean 0.78 pg/mL, and 1 other colitides with mean 0.21 pg/mL (Fisher’s exact test p-value: 0.36). In comparison, calprotectin levels were found in 21 CD with mean 661.13 ug/g, 17 UC with mean 855.26 ug/g, and other colitides with mean 177.15 ug/g (chi-square p-value: <0.0001). Upon further analysis, the only significant difference in calprotectin levels amongst the three variables was when comparing IBD (UC, CD or both) with other colitides (chi-square p-value: <0.0001). Conclusion: The study reaffirms fecal calprotectin as the preferred inflammatory marker in IBD compared to TNF-α in adults. This research was supported by an industry grant from UCB.