The Th1/Th2 immune-type response of the recurrent aphthous ulceration analyzed by cDNA microarray

Background: The reduced ability to activate oral tolerance plays a role in the pathogenesis of some gastrointestinal inflammatory diseases. This activation may reflect a preferential reduction of a T‐helper (Th)2‐ or Th3‐type response. In recurrent aphthous ulceration (RAU), genetic and environmental factors may contribute to low tolerance, permitting a cytotoxic reaction against the oral epithelium. The cytokine profile has not permitted the definition of RAU as resulting from enhanced Th1 or Th2 responses. A cDNA microarray study would allow the identification of differentially expressed genes and provide a basis for classification of the immune response. Methods: The cDNA from 29 samples of aphthae and from 11 samples of normal mucosa from aphthae‐free volunteers were hybridized on microarray membranes with 1176 genes. Results: Forty‐one differentially expressed genes were identified, and a higher expression level of the Th1 gene cluster in RAU was found. Conclusions: Microarrays permitted us definition of the gene expression profile of the lesion and identify an increased Th1 activity in RAU lesions.