AUTHOR=Crossland Rachel E. , Norden Jean , Ghimire Sakhila , Juric Mateja Kralj , Pearce Kim F. , Lendrem Clare , Collin Matthew , Mischak-Weissinger Eva , Holler Ernst , Greinix Hildegard T. , Dickinson Anne M. 

TITLE=Profiling Tissue and Biofluid miR-155-5p, miR-155*, and miR-146a-5p Expression in Graft vs. Host Disease

JOURNAL=Frontiers in Immunology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.639171

DOI=10.3389/fimmu.2021.639171

ISSN=1664-3224

ABSTRACT=Introduction
Acute graft versus host disease (aGvHD) is a frequent complication following allogeneic haematopoeitic transplantation (HSCT). Despite recent advances, there are no accepted biomarkers to determine development of aGvHD. MicroRNAs miR-146a and miR-155 have been previously associated with aGvHD and show promise as clinically translatable biomarkers. In this study, we performed comprehensive expression profiling of miR-146a, miR-155 and miR-155* expression in aGvHD target tissues and biofluids and relate expression to post-HSCT outcomes.

Materials and methods
MicroRNA expression was assessed by qRT-PCR in gastrointestinal, skin and skin explant biopsies. Analysis was also carried out in serum and urine biofluids including sequential time-point, independent, diagnostic and extracellular vesicle (EV) cohorts. Expression was related to aGvHD incidence, severity and overall survival.

Results
Expression of miR-155 (p=0.03) and miR-146a (p=0.03) was higher in GI samples at aGvHD onset (p=0.03) compared to no GvHD. In skin biopsies, expression of miR-155 (p=0.004) was upregulated in aGvHD compared to normal controls, while miR-146a expression was higher in aGvHD compared to no aGvHD biopsies (p=0.002). In serum, miR-155 (p=0.03) and miR-146a (p=0.02) expression was higher at day 14 (D14), while in urine expression was elevated at D7 post-HSCT in patients who developed aGvHD compared to those disease free. This was verified in an independent serum (miR-155 p=0.005, miR-146a p=0.003) and urine (miR-155 p=0.02, miR-146a p=0.04) cohort, where both microRNAs were also associated with aGvHD by ROC analysis. In serum and urine samples taken at the time of aGvHD symptoms, expression of miR-155 and miR-146a was also elevated (serum miR-155 p=0.03, miR-146a p<0.001; urine miR-155 p=0.02, miR-146a p=0.09). In contrast, miR-146a and miR-155 was downregulated at D14 in serum EVs and at D7 in urine EVs in patients who developed aGvHD compared to those that remained disease-free, in both an exploratory (serum miR-155 p=0.02, miR-146a p=0.06; urine miR-155 p=0.02, miR-146a p=0.07) and an independent cohort (serum miR-155 p=0.01, miR-146a p=0.02).

Conclusions
These results further support a role for miR-155 and miR-146a as non-invasive, clinically relevant biomarkers for aGvHD. However, the link between their involvement in generalised inflammation and in specific pathophysiology requires further investigation at a systemic level.