Involvement Of CCL2 Research Articles

CCL2‐ Dependent Macrophage Recruitment by Glioblastoma Stem Cells: The Role of Gα12 and YAP Signaling

Glioblastoma multiforme (GBM), the most malignant form of brain tumor, has an average survival rate of less than two years, associated with recurrence despite conventional interventions. GBM tumors contain myeloid cells, recruited in response to inflammatory cytokines which play a role in the tumor progression and may also contribute to immune suppression. Tumor associated macrophages interact with tumor cells and conversely tumor cells contribute to generation of the inflammatory immune cell environment. Gα12 protein-coupled receptors are regulated by inflammatory mediators often generated in the tumor cell environment. Stimulation of these receptors activates the transcriptional co-activator YAP (Yes-associated protein 1) which can in turn induce inflammatory gene expression. Our previous studies showed that knockdown of YAP in GSC-23 PDX cells significantly attenuated in vitro stemness, proliferation, and migration. In vivo experiments showed that YAP knockdown PDX cells formed significantly smaller tumors and had lower lethality than wild-type cells. Our more recent in vivo studies with GSC-23 cells suggested that there is a significant inflammatory response in the tumor cell environment. In order to determine if Gα12/YAP signaling in this glioma stem cell tumor line contributed to macrophage infiltration we utilized an in vitro. Transwell migration assay with human THP-1 macrophages on the top and GSC-23 cells on the bottom. Remarkably, the presence of GSC-23 cells strongly enhanced THP-1 cell migration and this could be mimicked almost fully by replacing the cells with medium in which they were cultured for 24 hours. One of the most efficacious mediators of macrophage migration is CCL2 (MCP-1). The involvement of CCL2 and its receptor CCR2 on THP-1 cell migration was demonstrated by the ability of the CCR2 blocker RS102895 to significantly inhibit the migratory response elicited by GSC-23 cells or cell medium. To understand whether the generation of CCL2 and thus the effect of the tumor cells on macrophage recruitment was specifically regulated, we examined GSC-23 cells in which YAP or Gα12 were deleted. YAP knockout prevented GSC-23 cell mediated migration suggesting that YAP regulates production of CCL2 by the GSC-23 cells. We observed that CCL2 mRNA levels were in fact significantly lower in YAP knockdown compared to WT cells. Notably this appeared to depend on the presence of the THP-1 cells suggesting that macrophage crosstalk to the GSC-23 tumor cells controls CCL2 generation. IL-6 mRNA levels were similarly regulated by THP-1 signaling to GSC-23 cells through YAP. Using a Gliovis tool to analyze data sets of GBM tumors, we determined that there is a highly significant Pearson's correlation between YAP1 and CCL2 gene expression as well as a correlation between YAP1 and IL-6 expression. Further of studies are underway to explore mechanisms responsible for this glioma stem cell /macrophages crosstalk in co-culture experiments. We suggest that YAP mediated cytokine generation by glioma stem cells represents a critical point for therapeutic intervention to disrupt recruitment of macrophages and interfere with their potential role in creating an immunosuppressive myeloid cell tumor microenvironment.

A Long Noncoding RNA, Antisense IL-7, Promotes Inflammatory Gene Transcription through Facilitating Histone Acetylation and Switch/Sucrose Nonfermentable Chromatin Remodeling.

Long noncoding RNAs are important regulators of gene expression in innate immune responses. Antisense IL-7 (IL-7-AS) is a newly discovered long noncoding RNA in human and mouse that has been reported to regulate the expression of IL-6. However, the potential function of IL-7-AS in innate immune system is not fully understood. In this study, we found that the expression of IL-7-AS is primarily dependent on the NF-κB and MAPK signaling pathways in macrophages and intestinal epithelial cells. Functionally, IL-7-AS promotes the expression of several inflammatory genes, including CCL2, CCL5, CCL7, and IL-6, in cells in response to LPS. Specifically, IL-7-AS physically interacts with p300 to regulate histone acetylation levels around the promoter regions of these gene loci. Moreover, IL-7-AS and p300 complex modulate the assembly of SWI/SNF complex to the promoters. IL-7-AS regulates chemotaxis activity of monocytes to intestine epithelial cells with involvement of CCL2. Therefore, our data indicate a new promoting role for NF-κB/MAPK-responsive IL-7-AS in the transcriptional regulation of inflammatory genes in the innate immune system although modulation of histone acetylation around the promoters of related genes.

CCL2/Monocyte Chemoattractant Protein 1 and Parathyroid Hormone Action on Bone.

Chemokines are small molecules that play a crucial role as chemoattractants for several cell types, and their components are associated with host immune responses and repair mechanisms. Chemokines selectively recruit monocytes, neutrophils, and lymphocytes and induce chemotaxis through the activation of G protein-coupled receptors. Two well-described chemokine families (CXC and CC) are known to regulate the localization and trafficking of immune cells in cases of injury, infection, and tumors. Monocyte chemoattractant protein 1 (MCP-1/CCL2) is one of the important chemokines from the CC family that controls migration and infiltration of monocytes/macrophages during inflammation. CCL2 is profoundly expressed in osteoporotic bone and prostate cancer-induced bone resorption. CCL2 also regulates physiological bone remodeling in response to hormonal and mechanical stimuli. Parathyroid hormone (PTH) has multifaceted effects on bone, depending on the mode of administration. Intermittent PTH increases bone in vivo by increasing the number and activity of osteoblasts, whereas a continuous infusion of PTH decreases bone mass by stimulating a net increase in bone resorption. CCL2 is essential for both anabolic and catabolic effects of PTH. In this review, we will discuss the pharmacological role of PTH and involvement of CCL2 in the processes of PTH-mediated bone remodeling.

Thiamine deficiency promotes T cell infiltration in experimental autoimmune encephalomyelitis: the involvement of CCL2.

Multiple sclerosis (MS) is a complex multifactorial disease that results from the interplay between environmental factors and a susceptible genetic background. Experimental autoimmune encephalomyelitis (EAE) has been widely used to investigate the mechanisms underlying MS pathogenesis. Chemokines, such as CCL2, are involved in the development of EAE. We have previously shown that thiamine deficiency (TD) induced CCL2 in neurons. We hypothesized that TD may affect the pathogenesis of EAE. In this study, EAE was induced in C57BL/6J mice by the injection of myelin oligodendroglial glycoprotein (MOG) peptides 35-55 with or without TD. TD aggravated the development of EAE, which was indicated by clinical scores and pathologic alterations in the spinal cord. TD also accelerated the development of EAE in an adoptive transfer EAE model. TD caused microglial activation and a drastic increase (up 140%) in leukocyte infiltration in the spinal cord of the EAE mice; specifically, TD increased Th1 and Th17 cells. TD upregulated the expression of CCL2 and its receptor CCR2 in the spinal cord of EAE mice. Cells in peripheral lymph node and spleen isolated from MOG-primed TD mice showed much stronger proliferative responses to MOG. CCL2 stimulated the proliferation and migration of T lymphocytes in vitro. Our results suggested that TD exacerbated the development of EAE through activating CCL2 and inducing pathologic inflammation.

Assessment of Genetic Effects of Polymorphisms in the MCP-1 Gene on Serum MCP-1 Levels and Myocardial Infarction in Japanese

Recently, the Framingham Heart Study reported that genetic variations in CCL2 influence serum levels of monocyte chemoattractant protein-1 (MCP-1) and the incidence of myocardial infarction (MI). The purpose of the present study was to investigate the possible involvement of CCL2 in the pathogenesis of atherosclerosis and MI in Japanese. Multiple regression analysis indicated that the MCP-1 levels were significantly influenced by various factors including age, body mass index, smoking, alcohol intake, high density lipoprotein-cholesterol, and systolic blood pressure. Moreover, the serum MCP-1 level was significantly correlated with intima - media thickness (p < 0.0001). However, this association disappeared when other clinical confounding factors were included in the analyses. Comprehensive analysis of common polymorphisms of CCL2 in a large community-based population and in subjects with MI found that the A(-2138)T polymorphism affected the serum MCP-1 level in a subgroup of subjects 65 years and older. However, no significant differences in the frequencies of any of the polymorphisms or haplotypes were found between subjects with and without MI. None of the polymorphisms in CCL2 affected carotid atherosclerosis. The serum MCP-1 level was a good surrogate marker of atherosclerosis in the present study population. Although genetic variations in CCL2 may have some influence on MCP-1 production, their influence does not seem to contribute appreciably to atherosclerosis in Japanese. The present results did not support the recently published findings from the Framingham Heart Study. The discrepancy between the 2 studies may be related to differences in confounding factors that contribute to MCP-1 levels and in the haplotype structure of the 2 populations.