Inhibition of triggering receptor expressed on myeloid cells-1 impairs thrombin generation

H3K4me3-Mediated FOXJ2/SLAMF8 Axis Aggravates Thrombosis and Inflammation in β2GPI/Anti-β2GPI-Treated Monocytes

Antiphospholipid syndrome (APS) is characterized by thrombus formation, poor pregnancy outcomes, and a proinflammatory response. H3K4me3-related monocytes activation are key regulators of APS pathogenesis. Therefore, H3K4me3 CUT&Tag and ATAC-seq are performed to examine the epigenetic profiles. The results indicate that the H3K4me3 signal and chromatin accessibility at the FOXJ2 promoter are enhanced in an in vitro monocyte model by stimulation with β2GPI/anti-β2GPI, which mimics APS, and decreases after OICR-9429 administration. Furthermore, FOXJ2 is highly expressed in patients with primary APS (PAPS) and is the highest in patients with triple-positive antiphospholipid antibodies (aPLs). Mechanistically, FOXJ2 directly binds to the SLAMF8 promoter and activates SLAMF8 transcription. SLAMF8 further interacts with TREM1 to stimulate TLR4/NF-κB signaling and prohibit autophagy. Knockdown of FOXJ2, SLAMF8, or TREM1 blocks TLR4/NF-κB and provokes autophagy, subsequently inhibiting the release of inflammatory and thrombotic indicators. A mouse model of vascular APS is established via β2GPI intraperitoneal injection, and the results suggest that OICR-9429 administration attenuates the inflammatory response and thrombus formation by inactivating FOXJ2/SLAMF8/TREM1 signaling. These findings highlight the overexpression of H3K4me3-mediated FOXJ2 in APS, which consequently accelerates APS pathogenesis by triggering inflammation and thrombosis via boosting the SLAMF8/TREM1 axis. Therefore, OICR-9429 is a promising candidate drug for APS therapy.

TREM-1 Modulates Dendritic Cells Maturation and Dendritic Cell-Mediated T-Cell Activation Induced by ox-LDL

Atherosclerosis is a chronic inflammatory disease. The triggering receptor expressed on myeloid cells-1 (TREM-1) plays a crucial role in inflammatory diseases; recently, it was identified as a major upstream proatherogenic receptor, but its mechanism is still unclear. In this study, we explore the role of TREM-1 on dendritic cells maturation and inflammatory responses induced by ox-LDL and its possible mechanism. Human dendritic cells were differentiated from blood monocytes and treated with ox-LDL. Naive autologous T cells were cocultured with pretreated DCs or treated directly. The expression of TREM-1 and inflammatory factors were evaluated by real-time PCR, western blot, and ELISA methods. And the expression of immune factors to evaluate the DCs maturation and T-cell activation were determined by the FACS. Our study showed that ox-LDL induced TREM-1 expression, DC maturation, and T-cell activation. T cells exposed to ox-LDL-treated DCs produced interferon-γ and interleukin-17 (IL-17). Blocking TREM-1 suppressed the DC maturation, showing lower expression of CD1a, CD40, CD86, CD83, and HLA-DR, and limited their production of tumor necrosis factor-alpha (TNF-α), IL-1β, IL-6, and monocyte chemoattractant protein-1 (MCP-1), meanwhile increased transforming growth factor-β(TGF-β) and IL-10 production. Ox-LDL induced miR-155, miR-27, Let-7c, and miR-185 expression; however, TREM-1 inhibiting decreased miRNA-155 expression. Furthermore, silencing miRNA-155 restores SOCS1 repression induced by ox-LDL. Experiments with T cells derived from carotid atherosclerotic plaques or healthy individuals showed similar results. Our results uncover a new link between ox-LDL and TREM-1 and may provide insight into this interaction in the context of atherosclerosis.

TREM-1 isoforms in bacterial infections: to immune modulation and beyond

The triggering receptor expressed on myeloid cells 1 (TREM-1) is an innate immunity receptor associated with the amplification of inflammation in sterile and non-sterile inflammatory disorders. Since its first description, the two isoforms of the receptor, membrane and soluble (mTREM-1 and sTREM-1, respectively) have been largely explored in the immunopathogenesis of several bacterial diseases and sepsis. The role of the receptor in these scenarios seems to be at least partly dependent on the source/type of bacteria, host and context. As uncontrolled inflammation is a result of several bacterial infections, the inhibition of the receptor has been considered as a promising approach to treat such conditions. Further, sTREM-1 has been explored as a biomarker for diagnosis and/or prognosis of several bacterial diseases. Therefore, this review aims to provide an updated insight into how the receptor influences and is influenced by bacterial infections, highlighting the advances regarding the use/manipulation of TREM-1 isoforms in biomedical research and clinical practice.

HBV upregulated triggering receptor expressed on myeloid cells-1 (TREM-1) expression on monocytes participated in disease progression through NF-Kb pathway

The triggering receptor expressed on myeloid cells-1 (TREM-1) signal is related to the continuous amplification of inflammatory pathway. However, it is not clear whether and how HBV can regulated the expression of TREM-1 on monocyte participated in the progression of liver disease. Here, we showed that the expression of TREM-1 on monocyte subsets were increased significantly in HBV related liver cirrhosis group compared with chronic infected group and healthy control group. HBsAg and HBeAg could up-regulated TREM-1 on monocyte by NF-KB pathway, and at least last for 72 h. Increased TREM-1 on monocyte might associated with high level of inflammatory cytokine (TNF-a, IL-1β and IL-6) and the activation of LX-2 cells. Bioinformatics analysis showed that the high expression of TREM-1 was related to the poor prognosis of hepatocellular carcinoma (HCC). The level of TREM-1 might help to predict the progression of HBV infected liver disease and treat target to prevent fibrosis progression.