Differential Expression Of TREM-1 In Myelogenous Leukemia Cells
Authors: Li Huiyu , Li Wenying , Yi Xiaoling , Huang Shiang , Liu Wei , Jiang Li , Yang Chao , Li Juan 
Published: October 2019

Abstract

Objectives
Triggering receptor expressed on myeloid cells (TREM) -1 is a receptor as a member of the immunoglobulin superfamily expressed on the cell-surface of neutrophils, monocytes and macrophages. This receptor amplifies the inflammatory response, activating the signaling pathway. TREM-1 expression is associated with mature myeloid cell development. TREM-1 is shed from the membrane of activated macrophages without the transmembrane and intracellular domains, and can be found as soluble TREM (sTREM)-1. Soluble TREM-1 is thought to negatively regulate TREM receptor signaling. Some studies currently reported that TREM-1 regulates the malignant behavior of cancer cells in lung cancer and HCC. However, no related studies about the role of TREM-1 in leukemia have been carried out. The aims of this study was investigated the TREM-1 expression in myelogenous leukemia cells.

Methods
Thirty-five patients with AML, twenty-five patients with CML and a control group of eleven healthy people were subjected to the study. TREM-1 expressions on the surfaces of leukemia cells were measured by flow cytometry. Plasma sTREM-1 levels were measured by ELISA.

Results
In this study, our results provide the first evidence that TREM-1 was differentially expressed in myelogenous leukemia cells. The TREM-1 mean ratio of median fluorescence intensity (mean ratio of MFI) was 3.13±0.88 and 2.52±0.40 in CML and AML patients, respectively. The TREM-1 mean ratio of MFI was 3.03±1.40 in myelogenous leukemia cell lines (K562, HL60, THP-1). The TREM-1 mean ratio of MFI was 5.37±0.88 in healthy controls. Compared to healthy controls, myelogenous leukemia cells had decreased TREM-1 expressions (P<0.001). The TREM-1 mean ratio of MFI was 4.89±0.60 in patients who are in complete remission after Novartis's Gleevec therapy. Compared with CML patient groups, patients who are in complete remission after Gleevec therapy had rising TREM-1 expressions (P<0.01). TREM-1 expressions of patients who are in complete remission after Gleevec therapy were slightly lower than the healthy controls, but this did not reach significance. No significant difference in TREM-1 expressions was seen between AML and CML patient groups, male and female patient groups, and cells derived from peripheral blood and bone marrow of the same leukemia patients (p>0.1).
In addition, the plasma sTREM-1 levels were measured by ELISA. sTREM-1 levels was 48.54±57.63pg/mL for AML group and 43.72±23.93pg/mL for CML group. Results indicated that plasma sTREM-1 levels significantly higher in AML and CML patients than that in healthy controls (P<0.01). However, there was no significant difference in plasma sTREM-1 levels observed in AML patient group compared with CML patient group, male patients group compared with female patients group, and plasma from peripheral blood compared with plasma from bone marrow of the same leukemia patients (p>0.1).
An ongoing project focuses on the relationship between the function of TREM-1 and occurrence, progression and prognosis of myelogenous leukemia, advances will be reported in time.

Conclusion
TREM-1 expression on leukemia cells was significantly lower in patients with AML and CML than those in healthy controls and patients in complete remission had increased TREM-1 expression. Patients with AML and CML had increased plasma soluble TREM-1. The TREM-1 expression on leukemia cells had an inverse correlation with plasma sTREM-1 level in AML and CML patients.

Disclosures:
No relevant conflicts of interest to declare.