Impact Of Monocytes Research Articles

Monocytes augment inflammatory responses in human aortic valve interstitial cells via β2-integrin/ICAM-1-mediated signaling.

Inflammatory infiltration in aortic valves promotes calcific aortic valve disease (CAVD) progression. While soluble extracellular matrix (ECM) proteins induce inflammatory responses in aortic valve interstitial cells (AVICs), the impact of monocytes on AVIC inflammatory responses is unknown. We tested the hypothesis that monocytes enhance AVIC inflammatory responses to soluble ECM protein in this study. Human AVICs isolated from normal aortic valves were cocultured with monocytes and stimulated with soluble ECM protein (matrilin-2). ICAM-1 and IL-6 productions were assessed. YAP and NF-κB phosphorylation were analyzed. Recombinant CD18, neutralizing antibodies against β2-integrin or ICAM-1, and inhibitor of YAP or NF-κB were applied. AVIC expression of ICAM-1 and IL-6 was markedly enhanced by the presence of monocytes, although matrilin-2 did not affect monocyte production of ICAM-1 or IL-6. Matrilin-2 up-regulated the expression of monocyte β2-integrin and AVIC ICAM-1, leading to monocyte-AVIC adhesion. Neutralizing β2-integrin or ICAM-1 in coculture suppressed monocyte adhesion to AVICs and the expression of ICAM-1 and IL-6. Recombinant CD18 enhanced the matrilin-2-induced ICAM-1 and IL-6 expression in AVIC monoculture. Further, stimulation of coculture with matrilin-2 induced greater YAP and NF-κB phosphorylation. Inhibiting either YAP or NF-κB markedly suppressed the inflammatory response to matrilin-2 in coculture. Monocyte β2-integrin interacts with AVIC ICAM-1 to augment AVIC inflammatory responses to soluble matrilin-2 through enhancing the activation of YAP and NF-κB signaling pathways. Infiltrated monocytes may promote valvular inflammation through cell-cell interaction with AVICs to enhance their sensitivity to damage-associatedmolecular patterns.

A Coculture Model Mimicking the Tumor Microenvironment Unveils Mutual Interactions between Immune Cell Subtypes and the Human Seminoma Cell Line TCam-2.

Testicular germ cell cancer (TGCC) is the most common type of cancer in young men. Seminomas account for around half of them and are characterized by a pronounced infiltration of immune cells. So far, the impact of the tumor microenvironment (TME) on disease progression, especially the interaction of individual immune cell subtypes with the tumor cells, remains unclear. To address this question, we used an in vitro TME model involving the seminoma-derived cell line Tcam-2 and immune cell subsets purified from human peripheral blood. T cells and monocytes were strongly activated when individually cocultured with Tcam-2 cells as revealed by increased expression of activation markers and pro-inflammatory cytokines both on the mRNA and protein level. Importantly, the interaction between tumor and immune cells was mutual. Gene expression of pluripotency markers as well as markers of proliferation and cell cycle activity were upregulated in Tcam-2 cells in cocultures with T cells, whereas gene expression of SOX17, a marker for seminomas, was unaltered. Interestingly, the impact of monocytes on gene expression of Tcam-2 cells was less pronounced, indicating that the effects of individual immune cell subsets on tumor cells in the TME are highly specific. Collectively, our data indicate that seminoma cells induce immune cell activation and thereby generate a strong pro-inflammatory milieu, whereas T cells conversely increase the proliferation, metastatic potential, and stemness of tumor cells. Although the employed model does not fully mimic the physiological situation found in TGCC in vivo, it provides new insights potentially explaining the connection between inflammatory infiltrates in seminomas and their tendency to burn out and metastasize.

Abstract 12451: Monocytes Enhance Inflammatory Responses to Soluble Matrilin-2 in Human Aortic Valve Interstitial Cells via the Interaction of β 2 -integrin With ICAM-1

Calcific aortic valve disease (CAVD) is a slow progressive disease. Chronic inflammation plays a crucial role in CAVD progression. Monocyte infiltration and macrophage accumulation are found in calcified aortic valves. Soluble extracellular matrix proteins can act as damage-associated molecular patterns to induce the pathobiology associated with CAVD in aortic valve interstitial cells (AVICs). While human AVICs exhibit inflammatory response to soluble matrilin-2, the impact of monocytes on this response is unknown. We hypothesized that monocytes enhance AVIC inflammatory response to soluble matrilin-2 by a mechanism involving cell-cell interaction. Methods and Results: Human AVICs isolated from normal aortic valves were cultured alone or cocultured with monocytes in the absence or presence of recombinant matrilin-2 (1, 2 or 4 μg/ml). AVIC expression of ICAM-1 and IL-6 following an exposure to any dose of matrilin-2 was markedly enhanced by the presence of monocytes although matrilin-2 in the tested dose range had no effect on monocyte production of ICAM-1 or IL-6. Monocytes adhered to AVICs following matrilin-2 stimulation. Interestingly, matrilin-2 up-regulated the expression of β 2 -integrin in monocytes and ICAM-1 in AVICs. Neutralization of β 2 -integrin or ICAM-1 in coculture with specific antibody reduced the number of monocytes adhering to AVICs and suppressed the expression of ICAM-1 and IL-6 . Conversely, addition of β 2 -integrin CD18 enhanced the expression of ICAM-1 and IL-6 in AVICs exposed to matrilin-2. Further, stimulation of coculture with matrilin-2 induced greater YAP and NF-κB phosphorylation compared to AVIC monoculture. Inhibition of either YAP or NF-κB markedly suppressed the inflammatory response to matrilin-2 in coculture. Conclusions: Monocyte β 2 -integrin interacts with AVIC ICAM-1 to augment AVIC inflammatory response to soluble matrilin-2 through enhancing the activation of YAP and NF-κB signaling pathways. Infiltrated monocytes may promote valvular inflammation through cell-cell interaction with AVICs to enhance their sensitivity to damage - associated molecular patterns.

Alteration of blood monocyte subsets in chronic rhinosinusitis with regard to anti-inflammatory 1,8-Cineol treatment

Background: Chronic rhinosinusitis (CRS) affects about 10% of the european population causing considerable disease burden. The inflammatory microenvironment is mainly Th2 driven, but the impact of monocytes is still poorly understood. Aim of this study was to comprehensively investigate the composition of circulating monocytes and T cells in CRSwNP and CRSsNP patients, particularly with regard to the therapeutic herbal monoterpene 1,8-Cineol. Methodology: We analyzed the distribution of CD14 and CD16 classified monocyte subsets and the T-cell subset composition with respect to their PD-1 and PD-L1 expression in the peripheral blood of CRS patients using flow cytometry. Additionally, the M1/M2 like macrophage infiltration in nasal tissue and polyps was examined by immunofluorescence staining. Results: Data revealed a decrease of classical monocytes accompanied by a significant increase of intermediate CD16+ monocytes in CRSwNP and CRSsNP patients compared to healthy donors. PD-L1 expression on overall monocytes was also significantly increased in CRSwNP and CRSsNP patients. CRS patients with a severe drop of the proportion of classical monocytes showed a significant restoration of this subset in response to two-week 1,8-Cineol treatment. Conclusions: Our data indicate a CRS-induced shift of peripheral monocyte subsets to more inflammatory phenotypes that might be reversed by the herbal drug 1,8-Cineol.

Brown adipose tissue monocytes support tissue expansion

Monocytes are part of the mononuclear phagocytic system. Monocytes play a central role during inflammatory conditions and a better understanding of their dynamics might open therapeutic opportunities. In the present study, we focused on the characterization and impact of monocytes on brown adipose tissue (BAT) functions during tissue remodeling. Single-cell RNA sequencing analysis of BAT immune cells uncovered a large diversity in monocyte and macrophage populations. Fate-mapping experiments demonstrated that the BAT macrophage pool requires constant replenishment from monocytes. Using a genetic model of BAT expansion, we found that brown fat monocyte numbers were selectively increased in this scenario. This observation was confirmed using a CCR2-binding radiotracer and positron emission tomography. Importantly, in line with their tissue recruitment, blood monocyte counts were decreased while bone marrow hematopoiesis was not affected. Monocyte depletion prevented brown adipose tissue expansion and altered its architecture. Podoplanin engagement is strictly required for BAT expansion. Together, these data redefine the diversity of immune cells in the BAT and emphasize the role of monocyte recruitment for tissue remodeling.

Impact of monocyte to high-density lipoprotein ratio on prevalent hyperuricemia: findings from a rural Chinese population

BackgroundMonocyte to high-density lipoprotein cholesterol ratio (MHR) is a novel inflammatory marker that has been used to predict various inflammation-related diseases. This study aims to explore the association between MHR and prevalent hyperuricemia in a rural Chinese population.Methods8163 eligible participants (mean age: 54.13 years, males: 45.71%) from northeast China were enrolled in this cross-sectional study between 2012 to 2013. MHR was determined as blood monocyte count ratio to high-density lipoprotein cholesterol concentration.ResultsThe prevalence of hyperuricemia was 12.86%. After adjusting for potential confounding factors, per SD increase of MHR caused a 25.2% additional risk for hyperuricemia, and the top quartile of MHR had an 82.9% increased risk for hyperuricemia compared with the bottom quartile. Additionally, smooth curve fitting and subgroup analyses showed a linear and robust association between MHR and prevalent hyperuricemia respectively. Finally, after introducing MHR into the established model of risk factors, the AUC displayed a significant improvement (0.718 vs 0.724, p = 0.008). Furthermore, Category-free net reclassification improvement (0.160, 95% CI: 0.096–0.224, P < 0.001) and integrated discrimination improvement (0.003, 95% CI: 0.002–0.005, P < 0.001) also demonstrated significant improvements.ConclusionsThe present study suggests that MHR was positively and independently correlated with prevalent hyperuricemia among rural Chinese adults. Our results also implicate an important value for MHR in optimizing the risk stratification of hyperuricemia.

Impact of human monocyte and macrophage polarization on NLR expression and NLRP3 inflammasome activation.

Inflammasomes are multiprotein complexes nucleating around an NLR (Nucleotide-binding domain and Leucine-rich Repeat containing protein), which regulate the secretion of the pro-inflammatory interleukin (IL)-1β and IL-18 cytokines. Monocytes and macrophages, the main cells expressing the inflammasome genes, adapt to their surrounding microenvironment by a phenotypic polarization towards a pro-inflammatory M1 phenotype that promotes inflammation or an anti-inflammatory M2 phenotype important for resolution of inflammation. Despite the importance of inflammasomes in health and disease, little is known about inflammasome gene expression in relevant human cells and the impact of monocyte and macrophage polarization in inflammasome gene expression. We examined the expression of several members of the NLR, caspase and cytokine family, and we studied the activation of the well-described NLRP3 inflammasome in an experimental model of polarized human primary monocytes and monocyte-derived macrophages (M1/M2 phenotypes) before and after activation with LPS, a well-characterized microbial pattern used in inflammasome activation studies. Our results show that the differentiation of monocytes to macrophages alters NLR expression. Polarization using IFN-γ (M1 phenotype), induces among the NLRs studied, only the expression of NOD2. One of the key results of our study is that the induction of NLRP3 expression by LPS is inhibited in the presence of IL-4+IL-13 (M2 phenotype) at both mRNA and protein level in monocytes and macrophages. Unlike caspase-3, the expression of inflammasome-related CASP1 (encodes caspase-1) and CASP4 (encodes caspase-4) is up-regulated in M1 but not in M2 cells. Interestingly, the presence of LPS marginally influenced IL18 mRNA expression and secretion, unlike its impact on IL1B. Our data provide the basis for a better understanding of the role of different inflammasomes within a given environment (M1 and M2) in human cells and their impact in the pathophysiology of several important inflammatory disorders.

Circulating monocytes and atherogenesis: From animal experiments to human studies

Despite significant improvements in the prevention and management of atherosclerosis, its consequences still remain a major cause of disability and mortality. Better understanding of pathophysiological processes implicated in the initial stages of atherogenesis is critical for the discovery of effective approaches to prevent ischaemic stage of the disease and to reduce huge economic and social burden currently associated with atherosclerosis (1). According to the current paradigm the atherosclerotic process is primarily initiated in the vascular wall itself where monocyte-derived macrophages transform to ‘foam’ cells by accumulating lipids (2). Consequent apoptosis or death of macrophages is largely responsible for necrotic core generation, progressive accumulation of free cholesterol and expansion of the necrotic core within plaques. Often, unbalanced generation of inflammatory cytokines by plaque monocyte-derived macrophages (e.g. via up-regulation of Toll-like receptors) as well as angiogenic promoting pathological plaque neovascularisation, and enzymes degrading extracellular matrix results in destabilisation of atherosclerotic plaques (3–5). Whilst a critical role of vascular wall monocyte-derived macrophages in atherosclerotic plaque formation is widely recognised, the impact of circulating monocytes on atherogenesis is less established. For example, accumulation of modified (mainly oxidised) lipids via scavenger receptors was, until recently, exclusively attributed to vascular wall resident macrophages rather than circulating monocytes (6). Oxidised low-density lipoproteins (LDL) taken up via scavenger receptors (e.g. CD36 and CD204) are delivered to lysosomes, where they undergo esterification by cholesterol esterase and are largely converted into free cholesterol and fatty acids (6). It has been reported that CD36 contributes 60–70% of cholesterol ester accumulation in macrophages exposed to oxidised LDL (7). Deletion of the genes encoding CD36 and CD204 retards the development of atherosclerotic lesions in animal models of atherosclerosis (6). However, circulating monocytes are equipped with these same scavenger receptors and may thus start accumulating lipids even prior to their migration to tissues and differentiation to macrophages (8). Exposure to modified LDL induces rapid ‘foam’ cell formation from freshly isolated peripheral blood monocytes, accompanied by upregulation of CD204 and CD36 (8). The clinical relevance of these findings is supported by the observation that an absence of CD36 on circulating monocytes in individuals from a Japanese population results in 40–50% reduction in oxidised LDL binding to monocyte-derived-macrophages compared to normal subjects (9). Certainly, monocyte counts are increased in patients with stenotic coronary artery disease and the Intermountain Heart Collaborative Study Group recently reported a population of 3,227 patients with or without coronary artery disease whereby high monocyte counts were independent predictors of future myocardial infarction and death (10). However, the impact of monocytes in atherogenesis may go far beyond direct lipid accumulation as they are also actively involved in inflammatory responses attributable to their principal function within the innate immune system. Indeed, Correspondence to: Dr. Eduard Shantsila University of Birmingham Centre for Cardiovascular Sciences, City Hospital Birmingham, B18 7QH, UK Tel: +44 121 554 3801, Fax: +44 121 554 4083 E-mail: e.shantsila@bham.ac.uk

T cell marker metagene predicts a favourable prognosis in estrogen receptor negative and Her2 positive breast cancers.

Abstract Abstract #1048 Background: Lymphocyte infiltration (LI) is often seen in breast cancer and has been suggested as a marker of host antitumor immune response but its importance remains controversial. A positive correlation of Her2 amplification/overexpression and LI has been described which was associated with a more favorable outcome. In rapidly proliferating tumors LI is a good prognostic indicator correlating with lymph node negativity, smaller tumor size, lower grade. However the impact of monocytes, B- and T-lymphocytes on prognosis are still a matter of debate.&amp;#x2028; Material and Methods: A database of 2110 primary invasive breast cancer samples from 14 microarray datasets was established. Only Affymetrix HG-U133A microarrays were included for full comparability. Feature reduction was achieved by generating metagenes from genes with strong correlation in unsupervised clustering. The relationship of the five major metagenes with different cell types in the sample as well as differentiation programs/pathways associated with specific expression profiles was analyzed.&amp;#x2028; Results: A large cluster of approximately 600 genes with functions in immune cells was consistently obtained in all datasets. The redundant information from several ProbeSets allowed the construction of robust metagenes which can be used as surrogate markers for the amount of different immune cell types in the breast cancer sample. However, rather complex relationships of these immunological metagenes with standard parameters of the tumors were observed. When different subgroups of tumors were analyzed for disease free survival the IgG metagene as a surrogate marker for B cells had no significant prognostic value. In contrast high expression of the T cell surrogate marker (LCK metagene) was beneficial among all subgroups of ER-negative tumors. Moreover a positive prognostic value of LCK metagene expression was also revealed for those ER-positive tumors with a Her2 overexpression. In addition a trend for a better response to neoadjuvant chemotherapy was detected for those ER negative tumors associated with lymphocyte infiltration as deduced from high expression of both IgG and LCK metagenes.&amp;#x2028; Conclusions: Tumor associated lymphocytes could represent an anti tumor response but on the other hand they might promote tumor progression by shifting the cytokine milieu toward angiogenic factors, inflammatory cytokines and matrix metallo-proteinases. Thus it is crucial to precisely define the specific subtypes of immune cells which are associated with the tumor. Our results demonstrate that this task can be accomplished by a detailed analysis of the expression of metagenes. These surrogate markers define subgroups of tumors with different prognosis. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1048.