Figure 2.

The function of TREM1 and TREM2 in fibrosis based on inflammation. (a) In pro-fibrogenic process, TREM1 expressed on Kupffer cells promotes the activation of hepatic stellate cells by increasing cytokines. TREM2⁺CD9⁺ macrophages also upregulate fibrillar collagen expression. (b) The decreased expression of TREM1 in KCs reduces cytokines and weakens the activation of quiescent hepatic stellate cells. In the low inflammatory level, activated hepatic stellate cells reverse into quiescent state and apoptosis. TREM, triggering receptors expressed on myeloid cells; LSECs, liver sinusoidal endothelial cells; aHSCs, activated hepatic stellate cells; qHSCs, quiescent hepatic stellate cells; KCs, Kupffer cells.