Ubiquitous Colonic Ileal Metaplasia Consistent with the Diagnosis of Crohn's Colitis among Indeterminate Colitis Cohorts.

Background: Inadequate differentiated diagnostic features of predominantly colonic inflammatory bowel diseases i.e., ulcerative colitis and Crohn's colitis, may lead to inexact diagnosis of "indeterminate colitis". About 15% of indeterminate colitis patients are diagnosed at colonoscopy, in colonic biopsies, and/or at colectomy. Managing outcomes of indeterminate colitis, given its unpredictable clinical presentation, depends on future diagnosis of colitis, Crohn's colitis or ulcerative colitis.

Objective: Overview the diagnostic efficacy of ectopic colonic ileal metaplasia and human α-defens 5 (DEFA5 alias HD5) for accurate delineation of indeterminate colitis into authentic Crohn's colitis and/ or ulcerative colitis.

Design: We describe a targeted protein for potentially differentiating indeterminate colitis into an accurate clinical subtype diagnosis of inflammatory bowel diseases i.e., ulcerative colitis and Crohn's colitis.

Patients: Twenty-one patients with the clinically inexact diagnosis of indeterminate colitis were followed, reassessed and data analyzed.

Main outcome measures: We observed that (i) some patients had their original diagnosis changed from indeterminate colitis to either ulcerative colitis or Crohn's colitis; and (ii) human α-defensin 5 is aberrantly overexpressed in Crohn's colitis.

Results: Fifteen of the twenty-one (71.4%) patients with indeterminate colitis had their inconclusive diagnosis changed; nine patients changed to ulcerative colitis and six to Crohn's colitis. In human colon surgical samples, Human α-defensin-5 was significantly upregulated in Crohn's colitis. In addition, Human α-defensin 5 processing enzyme, matrix metalloptotease-7 was inversely expressed compared to Human α- Defensin 5.

Limitation: Due to the sequence homology of the α-defensin class of proteins, preceding efforts to raise antibodies (Abs) against DEFA5 have limitations to produce adequate specificity. The Abs used in previous assays recognizes the α-defensins, active α-defensins 5 and inactive pro- α-defensins 5. Monoclonal antibodies (mAbs) to determine specificity and sensitivity of α-defensins 5, which is diagnostic of CC disease, and NOT other α-defensins is the limitation to overcome.

Conclusion: It is feasible to differentiate ulcerative colitis from Crohn's colitis among patients with inexact diagnosis of indeterminate colitis using Human α-defensin 5 as a molecular biosignature delineator.