Although liver biopsy is the gold standard for the identification of non-alcoholic steatohepatitis (NASH), limits associated with its invasiveness justify research into non-invasive markers. While a multitude of recently developed non-invasive biomarkers have been shown to effectively diagnose NASH, their modest accuracy in independent validation has restricted their qualification for routine clinical use. As such, reliable non-invasive markers for the diagnosis of NASH remain an unmet clinical need. Triggering receptor expressed on myeloid cells (TREM2), upregulated in nonparenchymal hepatic cells during liver injury, has been proposed by recent studies as a candidate marker.
The aim of this study was to assess the diagnostic accuracy of plasma TREM2 as a biomarker for NASH in patients with NAFLD and elevated liver stiffness.
Plasma TREM2 levels were found to be significantly elevated in patients with NASH. A link was also found between plasma TREM2 levels and individual histologic features of the NAFLD Activity Score (NAS), including steatosis, lobular inflammation, and ballooning. Its association with fibrosis, however, was found to be poor. Regarding cut-offs, a plasma TREM2 level of ≤38 ng/ml was found to be an optimal NASH rule‐out cut-off (sensitivity 90%; specificity 52%), whereas a plasma TREM2 level of ≥65 ng/ml was an optimal NASH rule‐in cut-off (specificity 89%; sensitivity 54%). Although these findings support plasma TREM2 as a reliable non-invasive biomarker for the diagnosis of NASH, future validation studies should be larger, include more patients with advanced fibrosis (≥F3), and further test TREM2 in combination with well-known markers of fibrosis.