Endothelial cell­derived CCL15 mediates the transmigration of fibrocytes through the CCL15­CCR1 axis in vitro.

Wound healing is a complex physiological process in which fibrocytes serve a vital role. However, the mechanism underlying the recruitment of fibrocytes during wound healing remains largely unknown. The present study aimed to investigate whether endothelial cells are involved in the recruitment of fibrocytes in wound healing. To mimic the in vivo angiogenic process, a co­culture system consisting of endothelial cells and fibrocytes was achieved using a permeable Transwell co­culture system. The expression of chemokines produced by endothelial cells with or without co­culture was then measured using a gene chip. Based on the dataset from chip analysis, chemokine ligand 15 (CCL15) produced by endothelial cells was identified, which likely serves a regulatory role in mediating the transmigration of fibrocytes. Overexpression of CCL15 in endothelial cells or chemokine receptor 1 (CCR1) in fibrocytes promoted the transmigration of fibrocytes, whilst silencing the expression of CCL15 in endothelial cells or that of CCR1 in fibrocytes attenuated the transmigration of fibrocytes. Results from the present study suggested that the CCL15­CCR1 axis between endothelial cells and fibrocytes serves a vital role in mediating the recruitment of fibrocytes during wound healing.

CCL15 Recruits Suppressive Monocytes to Facilitate Immune Escape and Disease Progression in Hepatocellular Carcinoma.

Chemokines play a key role in orchestrating the recruitment and positioning of myeloid cells within the tumor microenvironment. However, the tropism regulation and functions of these cells in hepatocellular carcinoma (HCC) are not completely understood. Herein, by scrutinizing the expression of all chemokines in HCC cell lines and tissues, we found that CCL15 was the most abundantly expressed chemokine in human HCC. Further analyses showed that CCL15 expression was regulated by genetic, epigenetic, and microenvironmental factors, and negatively correlated with patient clinical outcome. In addition to promoting tumor invasion in an autocrine manner, CCL15 specifically recruited CCR1+ cells toward HCC invasive margin, approximately 80% of which were CD14+ monocytes. Clinically, a high density of marginal CCR1+ CD14+ monocytes positively correlated with CCL15 expression and was an independent index for dismal survival. Functionally, these tumor-educated monocytes directly accelerated tumor invasion and metastasis through bursting various pro-tumor factors and activating signal transducer and activator of transcription 1/3, extracellular signal-regulated kinase 1/2, and v-akt murine thymoma viral oncogene homolog signaling in HCC cells. Meanwhile, tumor-derived CCR1+ CD14+ monocytes expressed significantly higher levels of programmed cell death-ligand 1, B7-H3, and T-cell immunoglobulin domain and mucin domain-3 that may lead to immune suppression. Transcriptome sequencing confirmed that tumor-infiltrating CCR1+ CD14+ monocytes were reprogrammed to upregulate immune checkpoints, immune tolerogenic metabolic enzymes (indoleamine and arginase), inflammatory/pro-angiogenic cytokines, matrix remodeling proteases, and inflammatory chemokines. Orthotopic animal models confirmed that CCL15-CCR1 axis forested an inflammatory microenvironment enriched with CCR1+ monocytes and led to increased metastatic potential of HCC cells. Conclusion: A complex tumor-promoting inflammatory microenvironment was shaped by CCL15-CCR1 axis in human HCC. Blockade of CCL15-CCR1 axis in HCC could be an effective anticancer therapy.

Loss of SMAD4 Promotes Lung Metastasis of Colorectal Cancer by Accumulation of CCR1+ Tumor-Associated Neutrophils through CCL15-CCR1 Axis.

PURPOSE: We have reported loss of SMAD4 promotes expression of CCL15 from colorectal cancer to recruit CCR1+ myeloid cells through the CCL15-CCR1 axis, which contributes to invasion and liver metastasis. However, the molecular mechanism of lung metastasis is yet to be elucidated. Our purpose is to determine whether similar mechanism is involved in the lung metastasis of colorectal cancer. EXPERIMENTAL DESIGN: In a mouse model, we examined whether SMAD4 could affect the metastatic activity of colorectal cancer cells to the lung through the CCL15-CCR1 axis. We immunohistochemically analyzed expression of SMAD4, CCL15, and CCR1 with 107 clinical specimens of colorectal cancer lung metastases. We also characterized the CCR1+ myeloid cells using several cell-type-specific markers. RESULTS: In a mouse model, CCL15 secreted from SMAD4-deficient colorectal cancer cells recruited CCR1+ cells, promoting their metastatic activities to the lung. Immunohistochemical analysis of lung metastases from colorectal cancer patients revealed that CCL15 expression was significantly correlated with loss of SMAD4, and that CCL15-positive metastases recruited approximately 1.9 times more numbers of CCR1+ cells than CCL15-negative metastases. Importantly, patients with CCL15-positive metastases showed a significantly shorter relapse-free survival (RFS) than those with CCL15-negative metastases, and multivariate analysis indicated that CCL15 expression was an independent predictor of shorter RFS. Immunofluorescent staining showed that most CCR1+ cells around lung metastases were tumor-associated neutrophil, although a minor fraction was granulocytic myeloid-derived suppressor cell. CONCLUSIONS: CCL15-CCR1 axis may be a therapeutic target to prevent colorectal cancer lung metastasis. CCL15 can be a biomarker indicating poor prognosis of colorectal cancer patients with lung metastases. Clin Cancer Res; 23(3); 833-44. ©2016 AACR.

CC-chemokine CCL15 expression and possible implications for the pathogenesis of IgE-related severe asthma.

Airway inflammation is accompanied by infiltration of inflammatory cells and an abnormal response of airway smooth muscle. These cells secrete chemokines and express the cell surface chemokine receptors that play an important role in the migration and degranulation of inflammatory cells. Omalizumab is a monoclonal antibody directed against immunoglobulin E, and its blocking of IgE signaling not only reduces inflammatory cell infiltration mediated by the Th2 immune response but also inhibits other immune responses. The chemokine CCL15 is influenced by omalizumab, and the source of CCL15 has been reported to be airway smooth muscle cells and basophils. CCL15 binds to its receptor CCR1, which has been reported to be expressed by various inflammatory cells and also by airway smooth muscle cells. Therefore, CCL15/CCR1 signaling could be a target for the treatment of asthma. We review the role of CCL15 in the pathogenesis of asthma and also discuss the influence of IgE-mediated immunomodulation via CCL15 and its receptor CCR1.

CFTR is the primary known apical glutathione transporter involved in cigarette smoke-induced adaptive responses in the lung.

One of the most abundant antioxidants in the lung is glutathione (GSH), a low-molecular-weight thiol, which functions to attenuate both oxidative stress and inflammation. GSH is concentrated in the epithelial lining fluid (ELF) of the lung and can be elevated in response to the increased oxidant burden from cigarette smoke (CS). However, the transporter(s) responsible for the increase in ELF GSH with cigarette smoke is not known. Three candidate apical GSH transporters in the lung are CFTR, BCRP, and MRP2, but their potential roles in ELF GSH transport in response to CS have not been investigated. In vitro, the inhibition of CFTR, BCRP, or MRP2 resulted in decreased GSH efflux in response to cigarette smoke extract. In vivo, mice deficient in CFTR, BCRP, or MRP2 were exposed to either air or acute CS. CFTR-deficient mice had reduced basal and CS-induced GSH in the ELF, whereas BCRP or MRP2 deficiency had no effect on ELF GSH basal or CS-exposed levels. Furthermore, BCRP or MRP2 deficiency had little effect on lung tissue GSH. These data indicate that CFTR is predominantly involved in maintaining basal ELF GSH and increasing ELF GSH in response to CS.

[Myeloma bone disease and RANKL signaling].

Multiple myeloma develops and expands almost exclusively in the bone marrow, and generates devastating bone destruction. Myeloma cells produce a variety of cytokines including MIP-1 to stimulate bone resorption by enhancing RANKL expression, and suppress bone formation by inhibiting osteoblast differentiation, leading to bone destruction and rapid loss of bone. The emerging role of the RANKL/RANK signaling axis provide a molecular rationale for consideration of targeting RANKL/RANK in a bone disease in myeloma. Given formation of vicious cycle between bone destruction and tumor progression, inhibiting RANKL signaling may also contribute to the suppression of myeloma expansion.

[Cytokines in bone diseases. Cytokines and myeloma bone disease].

Multiple myeloma develops and expands almost exclusively in the bone marrow, and generates devastating bone destruction. MM cells produce a variety of cytokines to stimulate bone resorption by enhancing osteoclast formation and suppress bone formation by inhibiting osteoblast differentiation, leading to bone destruction and rapid loss of bone. In these lesions, osteoclasts and bone marrow stromal cells/immature osteoblasts create a microenvironment suitable for myeloma cell growth and survival, thereby forming a vicious cycle between bone destruction and myeloma expansion.

Identification of the efflux transporter of the fluoroquinolone antibiotic ciprofloxacin in murine macrophages: studies with ciprofloxacin-resistant cells.

Ciprofloxacin, the most widely used totally synthetic antibiotic, is subject to active efflux mediated by a MRP-like transporter in wild-type murine J774 macrophages. To identify the transporter among the seven potential Mrps, we used cells made resistant to ciprofloxacin obtained by long-term exposure to increasing drug concentrations (these cells show less ciprofloxacin accumulation and provide a protected niche for ciprofloxacin-sensitive intracellular Listeria monocytogenes). In the present paper, we first show that ciprofloxacin-resistant cells display a faster efflux of ciprofloxacin which is inhibited by gemfibrozil (an unspecific MRP inhibitor). Elacridar, at a concentration known to inhibit P-glycoprotein and breast cancer resistance protein (BCRP), only slightly increased ciprofloxacin accumulation, with no difference between resistant and wild-type cells. Analysis at the mRNA (real-time PCR) and protein (Western blotting) levels revealed an overexpression of Mrp2 and Mrp4. Mrp4 transcripts, however, were overwhelmingly predominant (45% [wild-type cells] to 95% [ciprofloxacin-resistant cells] of all Mrp transcripts tested [Mrp1 to Mrp7]). Silencing of Mrp2 and Mrp4 with specific small interfering RNAs showed that only Mrp4 is involved in ciprofloxacin transport in both ciprofloxacin-resistant and wild-type cells. The study therefore identifies Mrp4 as the most likely transporter of ciprofloxacin in murine macrophages but leaves open a possible common upregulation mechanism for both Mrp4 and Mrp2 upon chronic exposure of eukaryotic cells to this widely used antibiotic.

Macrophage inflammatory protein-1 delta: a novel osteoclast stimulating factor secreted by renal cell carcinoma bone metastasis.

Approximately 30% of patients with renal cell carcinoma (RCC) develop bone metastasis, which is characterized by extensive osteolysis leading to severe bone pain and pathologic fracture. Although the mechanism of RCC-induced osteolysis is unknown, studies of bone metastasis have shown that tumor-induced changes in bone remodeling are likely mediated by alterations in the bone microenvironment. Here, we report the discovery of a novel osteoclast stimulatory factor secreted by RCC bone metastasis (RBM). Through microarray analysis, we found expression of the chemokine, macrophage inflammatory protein-1 delta (MIP-1 delta), to be increased in RBM versus patient-matched primary RCC tissues and confirmed this finding by quantitative reverse transcription-PCR (qRT-PCR) and ELISA (P < 0.05). Furthermore, MIP-1 delta expression in RBM tissues was significantly (P < 0.001) higher than in human bone marrow, suggesting a potential alteration of the bone microenvironment. The receptors for MIP-1 delta, CCR1 and CCR3, were expressed in both osteoclast precursors and mature, bone-resorbing osteoclasts as shown by qRT-PCR and Western analysis. In functional studies, MIP-1 delta stimulated chemotaxis of two osteoclast precursor cell types: murine bone marrow mononuclear cells (BM-MNC) and RAW 264.7 cells. Furthermore, MIP-1 delta treatment of murine calvaria caused increased bone resorption as determined by measurement of released calcium. Correspondingly, MIP-1 delta significantly enhanced osteoclast formation and activity in response to RANKL in both BM-MNC and RAW 264.7 cells. Taken together, these data suggest that MIP-1 delta expression is increased in RBM relative to RCC and bone marrow, and may promote RBM-induced osteolysis by stimulating the recruitment and differentiation of osteoclast precursors into mature osteoclasts.

Keeping out the bad guys: gateway to cellular target therapy.

Tumor-stromal interaction is implicated in many stages of tumor development, although it remains unclear how genetic lesions in tumor cells affect stromal cells. We have recently shown that inactivation of transforming growth factor-beta family signaling within colon cancer epithelium increases chemokine CC chemokine ligand 9 (CCL9) and promotes recruitment of the matrix metalloproteinase (MMP)-expressing stromal cells that carry CC chemokine receptor 1 (CCR1), the cognate receptor for CCL9. We have further shown that lack of CCR1 prevents the accumulation of MMP-expressing cells at the invasion front and suppresses tumor invasion. These results provide the possibility of a novel therapeutic strategy for advanced cancer--prevention of the recruitment of MMP-expressing cells by chemokine receptor antagonist.

Odontoblast marker gene expression is enhanced by a CC-chemokine family protein MIP-3alpha in human mesenchymal stem cells.

OBJECTIVE: Macrophage inflammatory protein-3 alpha (MIP-3alpha) is a major CC-chemokine family protein, which serves as a differentiation factor for mesenchymal cells, including osteoblasts and dental pulp cells. The purpose of this study was to investigate the influence of MIP-3alpha on human mesenchymal stem cell differentiation in vitro. DESIGN: Human mesenchymal stem cells were maintained in Dulbecco's modified Eagle's medium in the presence or absence of MIP-3alpha and the presence or absence of osteogenic factors (dexamethasone, beta-glycerophoshate and ascorbic acid). Alkaline phosphatase (ALP) activity was measured, and expression of odontoblast and osteoblast markers were examined by RT-PCR and Western blotting. RESULTS: MIP-3alpha alone did not increase ALP activity, as compared to controls. The combination of MIP-3alpha and osteogenic factors increased ALP activity beyond increases observed with osteogenic factors alone. mRNA expression of the odontoblast marker dspp was only detectable when MIP-3alpha was added together with osteogenic factors at day 7 in three out of four samples. DSP protein level was increased only in the samples treated with both MIP-3alpha and osteogenic factors until day 5. In contrast, MIP-3alpha did not influence levels of the osteoblast markers CBFA1 or BSP. CONCLUSIONS: The present study demonstrated that MIP-3alpha enhanced gene expression and protein levels of odontoblast-related genes, without affecting levels of the osteogenic proteins CBFA1 or BSP.

Critical role of dendritic cells in mouse mammary tumor virus in vivo infection.

Mouse mammary tumor virus (MMTV) is a milk-transmitted betaretrovirus that causes mammary tumors in mice. Although mammary epithelial cells are the ultimate targets of MMTV, the virus utilizes components of the host immune system to establish infection. Previous studies indicated that dendritic cells play a role in MMTV infection. Here we show that dendritic cells are the first cells to be infected by MMTV in vivo and that they are capable of producing infectious virus that can be transmitted to other cell types. Moreover, upon contact with the virus, dendritic cells became more mature and migrated in response to the chemokine macrophage inflammatory protein 3beta. Finally, we demonstrate that targeted ablation of dendritic cells in vivo dramatically attenuated MMTV infection. These data indicate that MMTV infection of dendritic cells is critical to initial propagation of the virus in vivo.

Bacterial infections of the cornea (Pseudomonas aeruginosa).

Pseudomonas aeruginosa is a common organism associated with bacterial keratitis, especially in extended wear contact lens users. Recent advances in the field have been made using animal models, including inbred murine models that are classed as resistant (cornea heals) versus susceptible (cornea perforates). Overall, studies with these inbred mice provide a better understanding of the mechanisms of innate immune responsiveness and abrogation of immune privilege operative after P. aeruginosa corneal infection.

Physiological and pharmacological functions of Mrp2, Mrp3 and Mrp4 as determined from recent studies on gene-disrupted mice.

The MRP family is composed of nine transporters, at least eight of which are lipophilic anion transporters that are capable of conferring resistance to various anticancer agents. Recently, mice with gene disruptions in Mrp2, Mrp3 and Mrp4 have been developed. This review will discuss insights into the physiological and pharmacological functions of Mrp2, Mrp3 and Mrp4 afforded by investigations of these new mouse models.

Monocyte chemoattractant protein 1, macrophage inflammatory protein 1 alpha, and RANTES recruit macrophages to the kidney in a mouse model of hemolytic-uremic syndrome.

The macrophage has previously been implicated in contributing to the renal inflammation associated with hemolytic-uremic syndrome (HUS). However, there is currently no in vivo model detailing the contribution of the renal macrophage to the kidney disease associated with HUS. Therefore, renal macrophage recruitment and inhibition of infiltrating renal macrophages were evaluated in an established HUS mouse model. Macrophage recruitment to the kidney was evident by immunohistochemistry 2 h after administration of purified Stx2 and peaked at 48 h postinjection. Mice administered a combination of Stx2 and lipopolysaccharide (LPS) showed increased macrophage recruitment to the kidney compared to mice treated with Stx2 or LPS alone. Monocyte chemoattractants were induced in the kidney, including monocyte chemoattractant protein 1 (MCP-1/CCL2), macrophage inflammatory protein 1alpha (MIP-1alpha/CCL3), and RANTES (CCL5), in a pattern that was coincident with macrophage infiltration as indicated by immunohistochemistry, protein, and RNA analyses. MCP-1 was the most abundant chemokine, MIP-1alpha was the least abundant, and RANTES levels were intermediate. Mice treated with MCP-1, MIP-1alpha, and RANTES neutralizing antibodies had a significant decrease in Stx2 plus LPS-induced macrophage accumulation in the kidney, indicating that these chemokines are required for macrophage recruitment. Furthermore, mice exposed to these three neutralizing antibodies had decreased fibrin deposition in their kidneys, implying that macrophages contribute to the renal damage associated with HUS.

A role for IL-1 receptor antagonist or other cytokines in the acute therapeutic effects of IVIg?

The exact mechanism of action of IVIg in the amelioration of immune thrombocytopenic purpura (ITP) is still unclear. Studies have suggested that IVIg may function through the regulation of cytokines, including interleukin-1 receptor antagonist (IL-1Ra), an inhibitor of phagocytosis. Using a mouse model relevant to ITP, we confirm an increase in mouse serum levels of IL-1Ra after exposure to IVIg, yet a recombinant IL-1Ra did not ameliorate thrombocytopenia. IVIg has also been shown to affect the expression of other regulatory cytokines. We have also recently established that IVIg specifically targets activating FcgammaRs on CD11c+ dendritic cells (DCs) as its primary mechanism of action in the amelioration of murine ITP. Herein, we show that IVIg functions therapeutically in mice lacking specific cytokines or their receptors that can potentially affect DC/macrophage function (IL-1 receptor, IL-4, IL-10, IL-12beta, TNF-alpha, IFN-gamma receptor, MIP-1alpha). This suggests that while IVIg may mediate the release of a variety of cytokines, the cytokines tested do not directly participate in the mechanism of IVIg action.

CCL20 chemokine induces both osteoblast proliferation and osteoclast differentiation: Increased levels of CCL20 are expressed in subchondral bone tissue of rheumatoid arthritis patients.

We evaluated the role of CCL20 (MIP-3alpha) chemokine in cells directly involved in the remodeling of bone tissue (osteoblasts and osteoclasts) and we confirmed its expression in the subchondral bone tissue of rheumatoid arthritis (RA) patients. The expression of CCL20 and of its receptor CCR6 was evaluated in osteoblasts isolated from bone tissue of post-traumatic (PT) patients. Functional tests were performed to evaluate osteoblast proliferation and matrix protein modulation. Immunohistochemical analysis for CCR6, CCL20, and RANKL was performed on bone samples from RA patients. The role of CCL20 was then analyzed in osteoclast differentiation. We found that in basal conditions CCR6, but not its ligand CCL20, was highly expressed by osteoblasts. Functional analysis on osteoblasts showed that CCL20 significantly increased cellular proliferation but did not affect matrix protein expression. Pro-inflammatory cytokines significantly induced the release of CCL20 and RANKL by human osteoblasts but did not modulate CCR6 expression. Increased expression of CCR6, CCL20, and RANKL was confirmed in RA subchondral bone tissue biopsies. We demonstrated that CCL20 was also an earlier inducer of osteoclast differentiation by increasing the number of pre-osteoclasts, thus favoring cell fusion and MMP-9 release. Our results add new insight to the important role of the CCL20/CCR6, RANKL system in the bone tissue of RA. The contemporary action of CCL20 on osteoblasts and osteoclasts involved in the maintenance of bone tissue homeostasis demonstrates the important role of this compartment in the evolution of RA, by showing a clear uncoupling between new bone formation and bone resorption.

Macrophage inflammatory protein 3alpha deficiency in atopic dermatitis skin and role in innate immune response to vaccinia virus.

BACKGROUND: Patients with atopic dermatitis (AD) are prone to disseminated viral skin infections and therefore are not vaccinated against smallpox because of potential complications. Macrophage inflammatory protein 3alpha (MIP-3alpha) is a C-C chemokine expressed by keratinocytes that exhibits antimicrobial activity against bacteria and fungi; however, its role in antiviral innate immunity is unknown. OBJECTIVE: Evaluate the level of MIP-3alpha in AD skin and its role in the innate immune response to vaccinia virus (VV). METHODS: Macrophage inflammatory protein 3alpha levels were evaluated using real-time RT-PCR, immunodot-blot, and immunohistochemistry. The antiviral activity of MIP-3alpha was determined using a standard viral plaque assay. RESULTS: Macrophage inflammatory protein 3alpha gene expression was significantly (P < .01) decreased in AD skin (0.21 +/- 0.05 ng MIP-3alpha/ng glyceraldehyde-3-phosphate dehydrogenase) compared with psoriasis skin (0.67 +/- 0.13). This was confirmed at the protein level using immunohistochemistry. We further demonstrate that T(H)2 cytokines downregulate MIP-3alpha expression. The importance of MIP-3alpha in the innate immune response against VV was established by first demonstrating that MIP-3alpha exhibits activity against VV. Second, VV replication was significantly increased (P < .01) in keratinocytes treated with an antibody to neutralize MIP-3alpha. CONCLUSION: The current study demonstrates that MIP-3alpha exhibits antiviral activity against VV and demonstrates the importance of MIP-3alpha in the innate immune response against VV. In addition, AD skin is deficient in MIP-3alpha, in part because of the overexpression of T(H)2 cytokines in AD skin. CLINICAL IMPLICATIONS: MIP-3alpha deficiency in AD skin contributes to patients' increased propensity toward eczema vaccinatum. Increasing MIP-3alpha or neutralizing T(H)2 cytokines could prevent adverse reactions in patients with AD after smallpox vaccination.

Functional expression of chemokine receptor CCR6 on human effector memory CD8+ T cells.

Since CCR6 is a receptor for the chemokine CCL20, which is produced in tissues such as intestine and colon, it is thought that T cells expressing CCR6 are involved in mucosal immunity. The expression and function of CCR6 on human CD8+ T cells have not well been analyzed, although it is known that this receptor is expressed on a subset of human CD8+ T cells. We here characterize human CCR6+ CD8+ T cells. Multi-color flow cytometric analysis demonstrated that CCR6+ cells are predominantly found among CD8+ T cells having the memory phenotype. The expression of CCR6 is positively and negatively correlated with that of CCR5 and CCR7, respectively. CCR6+ CD8+ T cells express granzyme A and a low level of perforin but not granzyme B. In addition, a major population among these cells has the ability to produce IFN-gamma and TNF-alpha but not IL-2. These results indicate that CCR6+ CD8+ T cells have characteristics of early effector memory cells rather than effector or central memory cells. A chemotaxis assay revealed that CCR6+ CD8+ T cells have the ability to migrate in response to CCL20, suggesting that these T cells migrate to tissues such as colon and are involved in mucosal immunity.