Expression of LFA-1 adhesion molecules on cisplatin-treated macrophages

Key immune-related gene ITGB2 as a prognostic signature for acute myeloid leukemia

Background

The tumor microenvironment (TME) has an essential role in tumorigenesis, progression, and therapeutic response in many cancers. Currently, the role of TME in acute myeloid leukemia (AML) is unclear. This study investigated the correlation between immune-related genes and prognosis in AML patients.

Methods

Transcriptome RNA-Seq data for 151 AML samples were downloaded from TCGA database (https://portal.gdc.cancer.gov/), and the immune related genes (irgs) were selected from Immport database. Bioinformatics screening was used to identify irgs for AML, and genes with a critical role in the prognosis of AML were selected for further analysis. To confirm the prognostic role of irgs in AML, we undertook protein-protein interaction (PPI) network analysis of the top 30 interacting genes. We then investigated associations between immune cell infiltration and prognosis in AML patients. Immunohistochemistry was used to validate protein expression levels between AML and normal bone marrow samples. Analysis of the drug sensitivity of the selected gene was then performed.

Results

The integrin lymphocyte function-associated antigen 1 (CD11A/CD18; ITGAL/ITGB2) was identified as the key immune-related gene that significantly influenced prognosis in AML patients. Overexpression of ITGB2 indicated poor prognosis in AML patients (P=0.007). Risk modeling indicated that a high-risk score led to poor outcomes (P=3.076e−08) in AML patients. The risk model showed accuracy for predicting prognosis in AML patients, with area under curve (AUC) at 1 year, 0.816; AUC at 3 years, 0.82; and AUC at 5 years, 0.875. In addition, we found that ITGB2 had a powerful influence on immune cell infiltration into AML TME. The results of immunohistochemistry showed that AML patients had significantly higher ITGB2 protein expression than normal samples. The AML patients were divided into 2 groups based on ITGB2 risk scores. Drug sensitivity test results indicated that the high-risk group was sensitive to cytarabine, axitinib, bosutinib, and docetaxel, but resistant to cisplatin and bortezomib.

Conclusions

In the present study, we found that ITGB2 may be able to serve as a biomarker for assessing prognosis and drug sensitivity in AML patients.

Leukocyte arrest: Biomechanics and molecular mechanisms of β2 integrin activation

Integrins are a group of heterodimeric transmembrane receptors that play essential roles in cell-cell and cell-matrix interaction. Integrins are important in many physiological processes and diseases. Integrins acquire affinity to their ligand by undergoing molecular conformational changes called activation. Here we review the molecular biomechanics during conformational changes of integrins, integrin functions in leukocyte biorheology (adhesive functions during rolling and arrest) and molecules involved in integrin activation.

Interaction between cisplatin treated murine peritoneal macrophages and L929 cells: involvement of adhesion molecules, cytoskeletons, upregulation of Ca2+ and nitric oxide dependent cytotoxicity

Murine peritoneal macrophages on treatment with cisplatin (10 microg/ml) showed increased binding to L929 cells. Cisplatin treated macrophage on co-incubation with L929 cells form a distinct cytoplasmic contact between the two cells. The plasmalemmae of the two cells fuse over a large surface area. The formation of contact between the cisplatin treated macrophage and L929 cell results in the induction of apoptosis in L929 cell. Untreated macrophages did not form a contact with L929 cells and no apoptosis is observed in L929 cells. Immunofluorescence microscopical studies clearly show the participation of cytoskeleton and the adhesion molecules in the formation of contact between the two cells. Further, a significant enhancement of the expression of iNOS and cytosolic Ca2+ was observed in cisplatin treated macrophages co-incubated with L929 cells. Cisplatin treated macrophages produced significant amount of NO when co-incubated with L929 cells, while there was minimal production of NO by untreated macrophages co-incubated with L929 cells. Cisplatin treated macrophage-induced L929 cell death was NO dependent, since L-NMMA (500 microM) significantly inhibited the cytotoxicity of L929 cells. The addition of excess L-arginine (2mM) reversed the L-NMMA induced inhibition of NO production and L929 cell cytotoxicity.

In vitro activation of murine peritoneal macrophages by monocyte chemoattractant protein-1: upregulation of CD11b, production of proinflammatory cytokines, and the signal transduction pathway

The CC chemokine monocyte chemotactic protein-1 (MCP-1) is a major mediator of monocyte/macrophage infiltration at the inflammatory sides under both physiologic and pathologic conditions. We report the ability of MCP-1 to activate murine peritoneal macrophages in vitro for enhanced expression of CD11b, macrophage-mediated cytotoxicity, and production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1). The macrophages treated with MCP-1 in vitro displayed significant cytolytic activity toward TNF-alpha-sensitive L929 cells in a dose-dependent manner. The macrophage-mediated L929 cytotoxicity was blocked in the presence of anti-TNF-alpha antibodies, suggesting the involvement of TNF-alpha. Production of TNF-alpha and IL-1 macrophages on MCP-1 treatment was maximum at 24 h of incubation with 100 ng/ml MCP-1. Enhanced TNF-alpha and IL-1beta mRNA expression was also demonstrated by RT-PCR, which revealed transcription of interferon gamma (IFN-gamma), IL-12, and related T cell-specific chemokine genes, KC and IP-10, in the MCP-1-treated macrophages. The pharmacologic inhibitors pertussis toxin (100 ng/ml), wortmannin (200 ng/ml), H-7 (10 microM), PD98059 (25 microM), and genistein (10 microg/ml) significantly inhibited TNF-alpha and IL-1 production in the MCP1-treated macrophages, suggesting the involvement of G-proteins, phosphoinositol-3-kinase (PI3K), protein kinase C, p42/44 MAPK, and tyrosine kinases in this process.