Phillip Ruiz¹, Tadafumi Asaoka¹, Panagiotis Tryphonopoulos¹, Deborah Cova¹, Akin Tekin¹, Debbie Weppler¹, Jennifer Garcia², Seigo Nishida¹, Leslie Smith², Jang Moon¹, Andreas Tzakis¹

¹Department of Surgery, University of Miami, Miami, FL, United States; ²Department of Pediatrics, University of Miami, Miami, FL, United States

Background: Small bowel transplantation (SBT) is becoming a preferred treatment for patients with irreversible intestinal failure. Despite continuous improvement of immunosuppression, SBT is plagued by a high incidence of acute cellular rejection (ACR) that is frequently intractable. Therefore, there is a need to detect novel insights that will lead to strategies to achieve better control of ACR. We hypothesized that particular miRNAs provide critical regulation of the intragraft immune and inflammatory response.

Purpose: The aim of our study is to detect the miRNAs involved in and critical to intestinal ACR.

Materials: We examined 26 small intestinal mucosal biopsies (AR/NR group; 15/ 11) obtained from recipients after SBT or multivisceral transplantation. We investigated the expression of 384 mature human miRNAs and 280 messenger RNAs (mRNAs) using the TaqMan® human microRNA plate and gene signature arrays (immune, inflammation and apoptosis), respectively. We validated the reproducibility of differentially expressed miRNAs (miR-142-3p, 132, 886-3p, 16, 19a, 194 and 375) in the additional 53 samples (AR/NR group; 21/32) using quantitative RT-PCR. Furthermore, we confirmed the expression and distribution of selected miRNAs with in situ hybridization in tissue.

Results: We identified 28 miRNAs and 58 mRNAs with significantly different expression levels between the AR and NR groups. Among them, we found a strong positive correlation between the intragraft expression levels of 3 miRNAs (miR-142-3p, 886-3p and 132) and 17 mRNAs especially associated with immune/inflammatory responses including CTLA4, GZMB and CD40. We visualized these miRNAs accumulation and co-localization with CD3 and CD14 proteins in explanted intestinal allograft with severe ACR.

Conclusion: Our data suggested miRNAs have a critical role in the activation of intestinal ACR. These differences in miRNA expression patterns can be used to identify robust biomarkers and potential novel therapeutic targets for immunosuppressive agents.