| Eosinophilic gastrointestinal diseases (EGID) are characterized by eosinophilic inflammation in different segments of the gastrointestinal tract, causing a variety of clinical symptoms with unknown causes. Among EGID, the most common type is eosinophilic esophagitis (EoE), and it has received significant scientific and clinical attention. Transcriptome analysis in EoE has dramatically advanced our understanding of the disease pathogenesis. In addition to EoE, recent studies by RNA sequencing has also facilitated the identification of tissue-specific transcriptomes in non-EoE EGID, namely eosinophilic gastritis (EoG), eosinophilic duodenitis (EoD), and eosinophilic colitis (EoC). These tissue-specific transcriptomes have substantiated the validation of disease concepts and diagnostic criteria; 1) The EoG transcriptome showed that molecular validation of histologic diagnostic criteria, suggesting the possibility of a molecular diagnosis, even in more ambiguous cases; 2) The EoD transcriptome closely associated with duodenal eosinophil levels, particularly when levels exceeded 50 - 60 eosinophils per high-power field, providing key insight to the field regarding eosinophil thresholds for EoD diagnosis; and 3) The EoC transcriptome showed that EoC is an independent disease with unique molecular profiles compared to those of healthy subjects and patients with inflammatory bowel disease (IBD) and that there was no increase in type 2 cytokines in EoC. Herein, we present and contrast the fundamental clinical and molecular characteristics of EGID. |
