A two-step proteomic approach identifies candidate biomarker in ulcerative colitis with concomitant primary sclerosing cholangitis.

• Introduction: Ulcerative colitis (UC) with concomitant primary sclerosing cholangitis (PSC-UC or PSC-IBD) is today considered a unique IBD entity, including a more malignant disease course compared with classical UC. Biomarkers for identifying UC patients at risk of developing PSC is lacking, which may delay the onset of endoscopy surveillance. Mass spectrometric development has enabled the use of formalin-fixed paraffin embedded tissue (FFPE) for high resolution proteome analysis. In this study, we search for PSC-IBD proteomic fingerprints in FFPE by utilizing mass spectrometry.Methods: Protein was extracted out of FFPE colon archival samples from PSC-IBD (n=9), UC (n=7), and healthy controls (n=7). IBD-patients were all in clinical remission, without biologics or steroids, and all UC patients had a history of pancolitis. Samples were processed by the Multienzyme Digestion FASP and were analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Proteins were quantified using the Total Protein Approach. Data was analysed using linear regression and in a multiple manner using random forest algorithms. Candidate findings were validated in a second cohort (n: PSC-IBD=16 UC=21) using the same proteomic technique. To make an over-all proteome comparison, we performed principal component analysis, as well as a meta-analysis for the most prominent findings.Results: In the exploratory proteomic step, 7279 unique proteins were detected. After statistical analysis including multiple testing, the top-5 proteins (CD47, LSM7, NDUFAF4, AGPAT1 and THEM192) were selected as candidate proteins. When validating these findings in a confirmatory cohort, AGPAT1 was verified (p=0.009). According to meta-analysis, AGPAT1 was also found to be the most distinctive protein between PSC-IBD and UC. The overall proteomic profiles in step 1 and step 2 (7706 proteins) confirmed small biologic variations between the IBD-groups.Conclusions: In this two-step proteomic study on remissive IBD, we were able to verify AGPAT1 as a colonic PSC-IBD biomarker. We found high overall proteome resemblance, in contrast to the phenotypical differences existing between PSC-IBD and UC. Our findings have possible implication in future PSC-IBD diagnostics, and adds further knowledge to the evasive PSC-IBD phenotype.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Gastroenterologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Gastroenterology and Hepatology (hsv//eng)

Keyword

IBD

PSC

ulcerative colitis

UC

PSC-UC

PSC-IBD

proteomics

AGPAT1

Medicinsk vetenskap

Medical Science

Publication and Content Type

vet (subject category)

ovr (subject category)