P-187 Immunohistochemical Distinction of Chronic Enteropathy Associated with SLCO2A1 from Crohn's Disease

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Abstract

Background:

Solute carrier organic anion transporter family member 2A1 gene (SLCO2A1) defines a transporter of prostaglandin. Recently, we have identified that recessive mutations in the SLCO2A1 gene as causative variants of chronic nonspecific multiple ulcers of the small intestine/chronic enteropathy associated with SLCO2A1 (CEAS) (PLoSGenet 2015). To date, however, the gastrointestinal expression of SLCO2A1 protein in patients with CEAS and Crohn's disease (CD) has not been reported.

Methods:

The immunohistochemical staining using a polyclonal anti-SLCO2A1 antibody (HPA013742) was performed on the specimens obtained by biopsy or surgical resection from 16 cases of inflammatory bowel diseases; 13 of CD, and 3 of CEAS. The extent of positive areas was scored either as 0 (none), 1 (1%–30%), 2 (31%–60%), or 3 (>60%), based on the vascular endothelial cell expressing SLCO2A1 in the respective lesions. The intensity of SLCO2A1 expression was scored either as 0 (negative), 1 (intermediate), or 2 (strong). The final expression score, extent score plus intensity score, was thus scored as 0, 2, 3, 4, or 5.

Results:

The expression of SLCO2A1 protein was positive in one of the 3 cases of CEAS (33%) and all 13 cases of CD (100%). The mean final expression score of CEAS was 1.6 (range, 0–5), while that of CD was 4.8 (range, 4–5). The score of SLCO2A1 in CEAS was lower than in CD (P = 0.03). Two CEAS patients with negative expression of SLCO2A1 had homozygous splice-site mutation in the SLCO2A1 gene, c.1461+1G>C (exon 7) or c.940+1G>A (exon 10). The other CEAS patient with positive expression of SLCO2A1 had compound heterozygous mutations of c.664G>A and c.1807C>T.

Conclusions:

The immunohistochemical staining for SLCO2A1 protein may be useful for the distinction of CEAS from CD.

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