The incidence of multiple myeloma has long been high, however, there are fewer studies on phosphatidylinositol 3-kinase (PI3K) /serine-threonine kinase (AKT) signaling pathway and M2 macrophage polarization promoting the progression of multiple myeloma.

To investigate the expression of M2 macrophages in patients with multiple myeloma and the mechanism of PI3K/AKT signaling pathway promoting M2 macrophage polarization.

Forty-eight multiple myeloma patients diagnosed in the Department of Hematology of the Affiliated Hospital of Guilin Medical University from October 2021 to April 2022 were selected as the test group, and thirty healthy volunteers (healthy donors of blood marrow transplantation) in the same period were selected as the control group. Peripheral blood was taken from the 2 group and mononuclear cells were isolated, the proportion of M2 macrophages was determined by flow cytometry. RPMI8226 cells were subcultured by cell passage, and mononuclear macrophages THP-1 cells were cultured as macrophages by phorbol ester differentiation. According to the experimental requirements, tumor cells were cultured and transfected with siRNA to silence phosphatase and tensin homolog (PTEN) and divided into three groups, including blank group, siRNA-PTEN experimental group, and siRNA control group; the supernatants of the above three groups were collected and added to the macrophage co-culture system and then divided into four groups including M0 macrophage group, tumor cell supernatant group, siRNA-PTEN supernatant group, and siRNA supernatant group. The protein expression levels of AKT, p-AKT, PI3K-p85, and p-PI3K-p85 in the blank group, siRNA-PTEN experimental group, and siRNA control group of multiple myeloma cell culture were determined by Western blot assay. The mRNA expression levels of MMP2 and MMP9 in the blank group, siRNA-PTEN experimental group and siRNA control group were determined by fluorescence quantitative polymerase chain reaction (PCR) . The expression levels of specific antibodies CD163, CD206, and F4/80 in M2 macrophages in M0 macrophage group, tumor cell supernatant group, siRNA-PTEN supernatant group, and siRNA supernatant group were determined by flow cytometry. The mRNA expression levels of arginase 1 (ARG-1) and interleukin 10 (IL-10) in M0 macrophage group, tumor cell supernatant group, siRNA-PTEN supernatant group, and siRNA supernatant group were determined by fluorescence quantitative PCR.

The expression level of M2 macrophages was higher in the test group than that in the control group (t=0.855, P<0.001) . The protein expression levels of p-AKT/AKT and p-PI3K-p85/PI3K-p85 in the siRNA-PTEN experimental group were higher than the blank group and siRNA control group (P<0.05) . The mRNA expression levels of MMP2 and MMP9 in the siRNA-PTEN experimental group were higher than the blank group and siRNA control group (P<0.05) . M2 macrophage specific antibody CD163+F4/80 and CD206+F4/80 in the siRNA-PTEN supernatant group were higher than the tumor cell supernatant and siRNA-PTEN supernatant group (P<0.05) . The mRNA expression levels of ARG-1 and IL-10 in the siRNA-PTEN supernatant group were higher than the tumor cell supernatant group and siRNA supernatant group (P<0.05) .

M2 macrophages are upregulated in multiple myeloma patients, and multiple myeloma cells can promote M2 macrophage polarization through activation of the PI3K/AKT signaling pathway, thereby regulating the myeloma cell microenvironment.

多发性骨髓瘤发病率长期居高不下，但目前关于磷脂酰肌醇-3-激酶（PI3K）/丝氨酸/苏氨酸激酶（AKT）信号通路和M2巨噬细胞极化促进多发性骨髓瘤发生进展的研究较少。

探讨M2巨噬细胞在多发性骨髓瘤患者中的表达及PI3K/AKT信号通路促进M2巨噬细胞极化的机制研究。

选取2021年10月—2022年4月于桂林医学院附属医院血液内科确诊的多发性骨髓瘤患者48例为试验组，选取同期健康志愿者（血液内科骨髓移植健康供者）30名为对照组。取2组研究对象外周血并分离单个核细胞，流式细胞术检测M2巨噬细胞比例。采用细胞传代培养RPMI8226细胞，通过佛波酯分化培养单核巨噬细胞THP-1为巨噬细胞。根据实验需要将瘤细胞培养并采用siRNA转染沉默磷酸酶基因（PTEN）分成3组：空白组、siRNA-PTEN实验组、siRNA对照组；收集以上3组细胞培养基上清液加入巨噬细胞共培养体系后分为4组：M0巨噬细胞组、瘤细胞上清液组、siRNA-PTEN上清液组、siRNA上清液组。采用Western blot实验检测多发性骨髓瘤细胞培养的空白组、siRNA-PTEN实验组、siRNA对照组的AKT、p-AKT、PI3K-p85、p-PI3K-p85蛋白表达水平。采用荧光定量聚合酶链式反应（PCR）检测多发性骨髓瘤细胞培养的空白组、siRNA-PTEN实验组、siRNA对照组的基质金属蛋白酶（MMP）2、MMP9的mRNA表达水平。采用流式细胞术检测多发性骨髓瘤上清液共培养的M0巨噬细胞组、瘤细胞上清液组、siRNA-PTEN上清液组、siRNA上清液组M2巨噬细胞中特异性抗体CD163、CD206、F4/80表达水平。采用荧光定量PCR检测多发性骨髓瘤上清液共培养的M0巨噬细胞组、瘤细胞上清液组、siRNA-PTEN上清液组、siRNA上清液组M2巨噬细胞特异标志物精氨酸酶1（ARG-1）、白介素10（IL-10）的mRNA表达水平。

试验组M2巨噬细胞表达水平高于对照组（t=0.855，P<0.001）。siRNA-PTEN实验组中p-AKT/AKT、p-PI3K-p85/PI3K-p85蛋白表达水平均高于空白组和siRNA对照组（P<0.05）。siRNA-PTEN实验组中MMP2、MMP9的mRNA表达水平均高于空白组和siRNA对照组（P<0.05）。siRNA-PTEN上清液组M2巨噬细胞特异性抗体CD163+F4/80、CD206+F4/80表达水平高于瘤细胞上清液组和siRNA上清液组（P<0.05）。siRNA-PTEN上清液组M2巨噬细胞特异标志物ARG-1、IL-10的mRNA表达水平高于瘤细胞上清液组和siRNA上清液组（P<0.05）。

多发性骨髓瘤患者中M2巨噬细胞表达上调，多发性骨髓瘤细胞可通过激活PI3K/AKT信号通路促进M2巨噬细胞极化，调控骨髓瘤细胞微环境。