Expression Microarray Analysis Identifies Novel Epithelial Derived Differentially Expressed Protein Markers in Eosinophilic Esophagitis
Andres Matoso, Vincent A Mukkada, Shaolei Lu, Renee Monahan, Kelly Cleveland, Lelia Noble, Shamlal Mangray, Murray B Resnick. Rhode Island Hospital, Providence, RI
Background: Gene expression studies in eosinophilic esophagitis (EoE) support an immune mediated etiology associated with differential regulation of inflammatory cells and epithelial derived genes. Our aims were to characterize epithelial gene expression alterations associated with EoE and to determine whether the differentially expressed proteins may prove to be useful immunohistochemical markers of EoE.
Design: Esophageal biopsies from pediatric patients with EoE before (EoE-BT) and after topical steroids therapy (EoE-AT; N=7) were screened by expression microarray (Affymetrics GeneChip), and the results validated by qRT-PCR. A larger group of biopsies from EoE patients (n=42) were used to evaluate protein expression by immunohistochemistry (IHC) compared with biopsies of patients with reflux esophagitis (GERD; n=15) and normal controls (n=17). IHC positivity was defined by moderate or strong staining in at least 10% of the epithelial cells.
Results: Microarray studies identified 31 epithelial derived genes differentially expressed (>3 fold change) including 12 upregulated and 19 downregulated genes. qRT-PCR validated overexpression of ALOX15 and TNFAIP6 and underexpression of FLG, SLURP1 and CRISP3. Compared to EoE-AT samples, expression of ALOX15 was 7.0 fold higher in EoE-BT (P=0.02) and expression of TNFAIP6 was 6.1 fold higher in EoE-BT compared to EoE-AT samples (P=0.04). Expression of the initially downregulated genes FLG, SLURP1 and CRISP3 were upregulated after therapy by a fold change of 5.3 for FLG (P=0.01), 2.4 for SLURP1 (P=0.02) and 40.1 for CRISP3 (P=0.02). Cytoplasmic staining for ALOX15 was strongly and diffusely positive in 95% of EoE and negative in all controls, EoE-AT and GERD biopsies (P<0.001). TNFAIP6 was positive in 88% of EoE and in 47%, 29% and 40% of controls, EoE-AT and GERD respectively (P=0.002). FLG was positive in 88% of controls and 100% of GERD, but negative in all EoE, and re-expressed in 86% of EoE-AT (P<0.001). SLURP1 expression was positive in all controls and GERD, but only positive in 5% of EoE and was re-expressed in EoE-AT (P<0.001). The majority of controls (89%) and GERD (100%) were positive for CRISP3 while EoE-BT were positive in 14% of samples (P<0.001) with partial recovery after treatment (43%).
Conclusions: We identified five novel epithelial proteins differentially expressed in EoE and easily detectable by IHC. One of these proteins, ALOX15, may prove to be a useful diagnostic marker and therapeutic target for EoE.
Monday, March 4, 2013 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 106, Monday Morning