Chemokine-induced extravasation of MonoMac 6 cells: chemotaxis and MMP activity

Cell type specific interleukin-6 induced responses in tumor keratinocytes and stromal fibroblasts are essential for invasive growth

Interleukin-6 (IL-6) is one of the major inflammatory interleukins that has been linked to cancer progression. In our model for human skin squamous cell carcinoma (SCC), IL-6 expression is strongly upregulated upon progression from benign tumors to highly malignant, metastasizing SCCs. We now demonstrate that IL-6 promotes malignant and invasive tumor growth in human skin SCCs by inducing cell type specific cytokine profiles in tumor keratinocytes and stromal fibroblasts, activating the latter towards a tumor associated fibroblast (TAF) phenotype. In three-dimensional organotypic cocultures in vitro invasive growth of IL-6 overexpressing tumor keratinocytes, is associated with increased expression of matrix metalloproteinase-2 (MMP-2), MMP-14 and tissue inhibitor of metalloproteinases-2, and clearly depends on IL-6 activated fibroblasts. IL-6-induced secretion of monocyte chemotactic protein-1 (MCP-1) in tumor keratinocytes and of hepatocyte growth factor in fibroblasts is crucial for regulating expression and activation of MMP-2. This functional role of IL-6 is confirmed in vivo. Here MMP-14 and MMP-2 expression occur exclusively in surface transplants of IL-6 overexpressing keratinocytes and fibroblasts are identified as important source of MMP-2. Our data indicate that tumor keratinocytes derived IL-6 activates stromal fibroblasts towards a TAF phenotype, promoting tumor invasion via enhanced expression and activation of MMP-2.

Divergent and Synergistic Regulation of Matrix Metalloprotease Production by Cytokines in Combination with C-C Chemokines

The chemotactic effects of chemokines on cells has long been known, but it is now clear that chemokines also have much broader activities and are also involved in a number of disease pathologies, such as rheumatoid arthritis, cancer metastasis and other inflammatory processes. This study investigates the effects of four C-C chemokines, CCL2, CCL3, CCL4 and CCL5 either alone or in the presence of two regulatory cytokines TNF-α and TGF-β and their effect on secretion of two matrix metalloproteases MMP, MMP-2 and MMP-9, and the expression of one membrane bound MMP, MMP-14, by a monocytic human cell line, MonoMac6. All four C-C chemokines were shown to be chemotactic, but only CCL2 and CCL4 had any significant stimulatory effect on MMP-9 and MMP-2, respectively. Both TNF-α and TGF-β were found to divergently enhance MMP-9 and MMP-2 secretion respectively, with stimulation indexes of two and five respectively. Simultaneous treatment with TNF-α and chemokine resulted in up to a fifteen-fold stimulation of MMP-9 secretion and treatment with TGF-β and chemokine resulted in up to a fifteen-fold stimulation of MMP-2 secretion, while TNF-α in combination with CCL4 stimulated MMP-14 expression five-fold. Chemokine receptor expression was also investigated using a calcium-sensitive dye and FACS analysis. CCL2, CCL3, and CCL5 all resulted in a detectable enhancement of cytoplasmic Ca2+concentration. CCL4 was unable to activate Ca2+ mobilization, despite the presence of CCR5, the receptor for CCL4. There appeared to be no correlation between MMP production and chemotaxis. The strong synergy between chemokines and cytokines and the enhanced production of MMP may signify the differential regulatory mechanisms of the two cytokines and chemokines in disease pathology.

Transcriptome profiling of primary murine monocytes, lung macrophages and lung dendritic cells reveals a distinct expression of genes involved in cell trafficking

Background

Peripheral blood monocytes (PBMo) originate from the bone marrow, circulate in the blood and emigrate into various organs where they differentiate into tissue resident cellular phenotypes of the mononuclear phagocyte system, including macrophages (Mϕ) and dendritic cells (DC). Like in other organs, this emigration and differentiation process is essential to replenish the mononuclear phagocyte pool in the lung under both inflammatory and non-inflammatory steady-state conditions. While many studies have addressed inflammation-driven monocyte trafficking to the lung, the emigration and pulmonary differentiation of PBMo under non-inflammatory conditions is much less understood.

Methods

In order to assess the transcriptional profile of circulating and lung resident mononuclear phagocyte phenotypes, PBMo, lung Mϕ and lung DC from naïve mice were flow-sorted to high purity, and their gene expression was compared by DNA microarrays on a genome-wide scale. Differential regulation of selected genes was validated by quantitative PCR and on protein level by flow cytometry.

Results

Differentially-expressed genes related to cell traffic were selected and grouped into the clusters (i) matrix metallopeptidases, (ii) chemokines/chemokine receptors, and (iii) integrins. Expression profiles of clustered genes were further assessed at the mRNA and protein levels in subsets of circulating PBMo (GR1- vs GR1+) and lung resident macrophages (alveolar vs interstitial Mϕ). Our data identify differentially activated genetic programs in circulating monocytes and their lung descendents. Lung DC activate an extremely diverse set of gene families but largely preserve a mobile cell profile with high expression levels of integrin and chemokine/chemokine receptors. In contrast, interstitial and even more pronounced alveolar Mϕ, stepwise downregulate gene expression of these traffic relevant communication molecules, but strongly upregulate a distinct set of matrix metallopetidases potentially involved in tissue invasion and remodeling.

Conclusion

Our data provide new insight in the changes of the genetic profiles of PBMo and their lung descendents, namely DC and Mϕ under non-inflammatory, steady-state conditions. These findings will help to better understand the complex relations within the mononuclear phagocyte pool of the lung.

Keratinocyte-derived chemokine plays a critical role in the induction of systemic inflammation and tissue damage after trauma-hemorrhage

Neutrophil infiltration is a crucial step in the development of organ dysfunction after trauma. We have previously shown that keratinocyte-derived chemokine (KC), a chemoattractant for neutrophils, is up-regulated after trauma-hemorrhage. To determine the role of KC after trauma-hemorrhage, the effect of a KC-neutralizing antibody on the posttraumatic inflammatory response was examined. One hour before surgery, male C3H/HeN mice were treated with an anti-KC antibody or isotype control. Animals were subjected to sham operation or trauma-hemorrhage and resuscitated with Ringer lactate thereafter. They were killed 2 h later, and Kupffer cells were isolated. Plasma levels, Kupffer cell production, and lung and liver content of TNF-alpha, IL-6, IL-10, monocyte chemoattractant protein 1, macrophage inflammatory protein 1alpha, and KC were determined by BD cytometric bead arrays. Myeloperoxidase content in lung and liver were measured as a parameter for neutrophil infiltration, and wet-to-dry weight ratios of these organs were also determined. Hepatocyte damage was assessed by measuring alpha-gluthathione S-transferase concentration. Administration of the anti-KC antibody before trauma-hemorrhage prevented increases in KC plasma levels, which was accompanied by amelioration of neutrophil infiltration and edema formation in lung and liver after trauma-hemorrhage. No effect on other cytokines in plasma or Kupffer cell release was observed. These results suggest that KC plays a pivotal role in neutrophil infiltration and organ damage after trauma-hemorrhage and resuscitation.

Soluble fractalkine prevents monocyte chemoattractant protein-1-induced monocyte migration via inhibition of stress-activated protein kinase 2/p38 and matrix metalloproteinase activities

In this study, we address the question of the cross-talk between two chemokines that are cosecreted during inflammation, namely monocyte chemoattractant protein-1 (MCP-1) and soluble fractalkine (s-FKN), toward monocyte migration. We found that s-FKN fails to induce MonoMac6 cell migration per se. Interestingly, this chemokine antagonizes transendothelial migration and chemotaxis of MonoMac6 cells and freshly isolated human monocytes induced by MCP-1, indicating a direct effect of s-FKN on monocytic cells. In this study, we found that stress-activated protein kinase (SAPK)1/c-Jun N-terminal kinase 1 and SAPK2/p38 are involved in the control of MCP-1-induced MonoMac6 cell migration. We demonstrated that s-FKN abrogates the MCP-1-induced SAPK2/p38 activation as well as the upstream Pyk2 activity. Furthermore, we observed that s-FKN also inhibits the activity of a major matrix metalloproteinase (MMP), namely MMP-2. Taken collectively, our results indicate that the s-FKN antagonizes the chemoattractant effect of MCP-1 on monocytes, likely by inhibiting crucial signaling pathways, like SAPK2/p38 and MMP-2 activities.