Tyrosine phosphorylation-mediated signal transduction in MCP-1-induced macrophage activation: role for receptor dimerization, focal adhesion protein complex and JAK/STAT pathway

Ion channel expression and function in glioblastoma multiforme (GBM): pathophysiological mechanisms and therapeutic potential

Glioblastoma Multiforme (GBM) is a highly malignant and diffusely invasive WHO Grade IV brain tumor arising from glial and neural stem cells. GBM is characterized by rapid proliferation and migration, aggressive invasion of local brain parenchyma, a hypoxic microenvironment, resistance to apoptosis and high vascular remodeling and angiogenesis. These hallmarks contribute to a near universal tumor recurrence after treatment or resection and poor patient prognosis. Ion channels, a superfamily of proteins responsible for permitting ion flux across otherwise impermeant membranes, show extensive remodeling in GBM with aberrant function mechanistically linked to manipulation of each of these hallmarks. In this review, we will discuss the known links between ion channel expression and activity and cellular processes that are enhanced or perturbed during GBM formation or progression. We will also discuss the extent to which basic or translational findings on ion channels in GBM samples or cell lines have shown preclinical promise towards the development of improved therapeutics against GBMs.

Ulipristal acetate, a selective progesterone receptor modulator, induces cell death via inhibition of STAT3/CCL2 signaling pathway in uterine sarcoma

Ulipristal acetate (UPA) is a selective progesterone receptor modulator and is used for the treatment of uterine leiomyoma (a benign tumor). Uterine sarcoma which is highly malignant cancer with a poor prognosis is clinically resembled with uterine leiomyoma. There has been no experimental research on the effect of UPA on uterine sarcoma. In this study, we examined the efficacy of UPA in uterine sarcoma with in vitro and in vivo animal models. Cytotoxicity of UPA was determined in uterine sarcoma cell lines (MES-SA, SK-UT-1, and SK-LMS-1). Apoptotic genes and signaling pathways affected by UPA were analyzed by complementary DNA (cDNA) microarray of uterine sarcoma cell lines and western blot, respectively. An in vivo efficacy of UPA was examined with uterine sarcoma cell line- and patient-derived xenograft (PDX) mice models. UPA inhibited cell growth in uterine sarcoma cell lines and primary culture cells from a PDX mouse (PDX-C). cDNA microarray analysis revealed that CCL2 was highly down-regulated by UPA. Phosphorylation and the total expression of STAT3 were inhibited by UPA. UPA also inhibited CCL2 and STAT3 in PDX-C. The inhibitory effect of UPA had not changed in the overexpression of PR and treatment of progesterone. In vivo efficacy studies with cell line-derived xenografts and a PDX model with leiomyosarcoma, a typical uterine sarcoma, demonstrated that UPA significantly decreased tumor growth. UPA had significant anti-tumor effects in uterine sarcoma through the inhibition of STAT3/CCL2 signaling pathway and might be a potential therapeutic agent to treat this disease.

Amelioration effects of α-viniferin on hyperuricemia and hyperuricemia-induced kidney injury in mice

BACKGROUND

α-Viniferin, the major constituent of the roots of Caragana sinica (Buc'hoz) Rehder with a trimeric resveratrol oligostilbenoid skeleton, was demonstrated to possess a strong inhibitory effect on xanthine oxidase in vitro, suggesting it to be a potential anti-hyperuricemia agent. However, the in vivo anti-hyperuricemia effect and its underlying mechanism were still unknown.

PURPOSE

The current study aimed to evaluate the anti-hyperuricemia effect of α-viniferin in a mouse model and to assess its safety profile with emphasis on its protective effect on hyperuricemia-induced renal injury.

METHODS

The effects were assessed in a potassium oxonate (PO)- and hypoxanthine (HX)-induced hyperuricemia mice model by analyzing the levels of serum uric acid (SUA), urine uric acid (UUA), serum creatinine (SCRE), serum urea nitrogen (SBUN), and histological changes. Western blotting and transcriptomic analysis were used to identify the genes, proteins, and signaling pathways involved.

RESULTS

α-Viniferin treatment significantly reduced SUA levels and markedly mitigated hyperuricemia-induced kidney injury in the hyperuricemia mice. Besides, α-viniferin did not show any obvious toxicity in mice. Research into the mechanism of action of α-viniferin revealed that it not only inhibited uric acid formation by acting as an XOD inhibitor, but also reduced uric acid absorption by acting as a GLUT9 and URAT1 dual inhibitor as well as promoted uric acid excretion by acting as a ABCG2 and OAT1 dual activator. Then, 54 differentially expressed (log₂ FPKM ≥ 1.5, p ≤ 0.01) genes (DEGs) repressed by the treatment of α-viniferin in the hyperuricemia mice were identified in the kidney. Finally, gene annotation results revealed that downregulation of S100A9 in the IL-17 pathway, of CCR5 and PIK3R5 in the chemokine signaling pathway, and of TLR2, ITGA4, and PIK3R5 in the PI3K-AKT signaling pathway were involved in the protective effect of α-viniferin on the hyperuricemia-induced renal injury.

CONCLUSIONS

α-Viniferin inhibited the production of uric acid through down-regulation of XOD in hyperuricemia mice. Besides, it also down-regulated the expressions of URAT1 and GLUT9 and up-regulated the expressions of ABCG2 and OAT1 to promote the excretion of uric acid. α-Viniferin could prevent hyperuricemia mice from renal damage by regulating the IL-17, chemokine, and PI3K-AKT signaling pathways. Collectively, α-viniferin was a promising antihyperuricemia agent with desirable safety profile. This is the first report of α-viniferin as an antihyperuricemia agent.

Chemokine CCL2 from proximal tubular epithelial cells contributes to sepsis-induced acute kidney injury

Damage-associated molecular patterns secreted from activated kidney cells initiate inflammatory response, a critical step in the development of sepsis-induced acute kidney injury (AKI). However, the underlying mechanism remains to be clarified. Here, we established a mouse model of sepsis-induced AKI through intraperitoneal injection of lipopolysaccharide (LPS), and demonstrated that LPS induced dramatical upregulation of C-C motif chemokine ligand 2 (CCL2) at both the mRNA and the protein levels in kidney, which was mainly expressed by tubular epithelial cells (TECs), especially by proximal TECs. Proximal tubule-specific ablation of CCL2 reduced LPS-induced macrophage infiltration, proinflammatory cytokine expression, and attenuated AKI. In vitro, using transwell migration assay, we found that deficiency of CCL2 in TECs decreased macrophage migration ability. However, myeloid-specific depletion of CCL2 could not protect the kidneys from the aforementioned effects. Mechanistically, LPS activated toll like receptor (TLR) 2 signaling in TECs, which induced activation of its downstream effector nuclear factor (NF)-κB. Blockade of TLR2 signaling or inhibition of NF-κB activation in TECs significantly suppressed LPS-induced CCL2 expression. Furthermore, ChIP analyses confirmed a direct binding of NF-κB p65 in the CCL2 promoter regein, and LPS increased the binding of NF-κB p65 to CCL2 promoter, suggesting that TLR2/NF-κB p65 regulates CCL2 expression in TECs. Together, these results demonstrate that endogenous CCL2 released from PTECs, not from myeloid cells was responsible for sepsis-induced kidney inflammation and AKI. Specificly targeting tubular TLR2/NF-κB/CCL2 signaling may be a potential therapeutic strategy for prevention or attenuation of septic AKI.

Cytokine production and the effects of oclacitinib in three canine mast cell tumour cell lines

BACKGROUND

Cytokines are capable of manipulating the tumour microenvironment supporting tumour growth. Interleukin (IL)-8 and monocyte chemoattractant protein (MCP)-1, shown to be produced by various tumours, can negatively affect prognosis. The production of cytokines by canine mast cell tumours (MCT) has not been reported.

HYPOTHESIS/OBJECTIVES

We hypothesise that MCT cell lines produce IL-8 and/or MCP-1 in addition to other cytokines, and that their production can be modulated by the Janus kinase (JAK) inhibitor oclacitinib. This pilot study aims to investigate the production of IL-8, MCP-1 and nine additional cytokines in three canine MCT cell lines, and determine the effects of oclacitinib on their production.

METHODS AND MATERIALS

Reverse transcriptase-PCR was used to detect the expression of IL-8 and MCP-1 mRNA in three MCT cell lines (CoMS, CM-MC1 and VI-MC1). The supernatant of the cell lines was evaluated for the presence of 11 cytokines [IL-2, -6, -7, -8, -10, -15 and -18, and MCP-1, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon (IFN)γ and tumour necrosis factor (TNF)α] by enzyme-linked immunosorbent assay (ELISA). The IC₅₀ of oclacitinib was identified for each cell line. ELISA was performed again to compare changes in IL-8 and MCP-1 in treated cell lines versus untreated controls.

RESULTS

Interleukin-8 and MCP-1 were produced by all MCT cell lines tested. Oclacitinib significantly decreased the release of IL-8 in the CoMS cell line and of MCP-1 in CoMS and VI-MC1 in clinically relevant concentrations. Furthermore, oclacitinib significantly decreased the proliferation of all three cell lines.

CONCLUSIONS

Interleukin-8 and MCP-1 are produced by canine MCT cell lines. Modulation of their production is possible with oclacitinib.

MCP-1 targeting: Shutting off an engine for tumor development

A large amount of research has proven that monocyte chemotactic protein-1 (MCP-1) is associated with different types of disease, including autoimmune, metabolic and cardiovascular diseases. In addition, several studies have found that MCP-1 is associated with tumor development. MCP-1 expression level in the tumor microenvironment is associated with tumor development, including in tumor invasion and metastasis, angiogenesis, and immune cell infiltration. However, the precise mechanism involved is currently being investigated. MCP-1 exerts its effects mainly via the MCP-1/C-C motif chemokine receptor 2 axis and leads to the activation of classical signaling pathways, such as PI3K/Akt/mTOR, ERK/GSK-3β/Snail, c-Raf/MEK/ERK and MAPK in different cells. The specific mechanism is still under debate; however, target therapy utilizing MCP-1 as a neutralizing antibody has been found to have a detrimental effect on tumor development. The aim of the present review was to examine the effect of MCP-1 on tumor development from several aspects, including its structure, its involvement in signaling pathways, the participating cells, and the therapeutic agents targeting MCP-1. The improved understanding into the structure of MCP-1 and the mechanism of action may facilitate new and practical therapeutic agents to achieve maximum performance in the treatment of patients with cancer.

Phosphoproteomic characterization of the signaling network resulting from activation of the chemokine receptor CCR2

Leukocyte recruitment is a universal feature of tissue inflammation and regulated by the interactions of chemokines with their G protein-coupled receptors. Activation of CC chemokine receptor 2 (CCR2) by its cognate chemokine ligands, including CC chemokine ligand 2 (CCL2), plays a central role in recruitment of monocytes in several inflammatory diseases. In this study, we used phosphoproteomics to conduct an unbiased characterization of the signaling network resulting from CCL2 activation of CCR2. Using data-independent acquisition MS analysis, we quantified both the proteome and phosphoproteome in FlpIn-HEK293T cells stably expressing CCR2 at six time points after activation with CCL2. Differential expression analysis identified 699 significantly regulated phosphorylation sites on 441 proteins. As expected, many of these proteins are known to participate in canonical signal transduction pathways and in the regulation of actin cytoskeleton dynamics, including numerous guanine nucleotide exchange factors and GTPase-activating proteins. Moreover, we identified regulated phosphorylation sites in numerous proteins that function in the nucleus, including several constituents of the nuclear pore complex. The results of this study provide an unprecedented level of detail of CCR2 signaling and identify potential targets for regulation of CCR2 function.

The multilayered complexity of the chemokine receptor system

The chemokines receptor family are membrane-expressed class A-specific seven-transmembrane receptors linked to G proteins. Through interaction with the corresponding ligands, the chemokines, they induce a wide variety of cellular responses including cell polarization, movement, immune and inflammatory responses, as well as the prevention of HIV-1 infection. Like a Russian matryoshka doll, the chemokine receptor system is more complex than initially envisaged. This review focuses on the mechanisms that contribute to this dazzling complexity and how they modulate the signaling events triggered by chemokines. The chemokines and their receptors exist as monomers, dimers and oligomers, their expression pattern is highly regulated, and the ligands can bind distinct receptors with similar affinities. The use of novel imaging-based technologies, particularly real-time imaging modalities, has shed new light on the very dynamic conformations that chemokine receptors adopt depending on the cellular context, and that affect chemokine-mediated responses. This complex scenario presents both challenging and exciting opportunities for drug discovery.

Could signal transducer and activator of transcription 3 be a therapeutic target in obesity-related gastrointestinal malignancy?

INTRODUCTION

A large body of evidence has implicated the signal transducer and activator of transcription (STAT) family and particularly the ubiquitously expressed STAT3 protein in the pathogenesis of colorectal, hepatocellular, gastric and pancreatic carcinoma.

DISCUSSION

Concomitantly, an increasing body of epidemiological evidence has linked obesity and its associated pro-inflammatory state with the development of gastrointestinal cancers. Visceral adipose tissue is no longer considered inert and is known to secrete a number of adipocytokines such as leptin, interleukin (IL)-6, IL-8, IL-1β and tumour necrosis factor-alpha (TNF-α) into the surrounding environment. Interestingly, these adipocytokines are strongly linked with the Janus kinase (JAK)/STAT pathway of signal transduction and there is experimental evidence linking IL-1β, IL-8 and TNF-α to JAK/STAT signaling in other tissues. The result is an up-regulation of a wide range of anti-apoptotic, pro-metastatic and pro-angiogenic genes and processes. This is particularly relevant for gastrointestinal malignancy as these factors have the potential to signal adjacent endothelial cells in a paracrine manner.

CONCLUSION

This review examines the potential role of the STAT3 signaling pathway in the pathogenesis of obesity-related gastrointestinal malignancy and the potential therapeutic role of STAT3 blockade given its status as a signaling hub for a number of inflammatory adipocytokines.

Jak3 enables chemokine-dependent actin cytoskeleton reorganization by regulating cofilin and Rac/Rhoa GTPases activation

We have previously shown that Jak3 is involved in the signaling pathways of CCR7, CCR9 and CXCR4 in murine T lymphocytes and that Jak3^−/− lymphocytes display an intrinsic defect in homing to peripheral lymph nodes. However, the molecular mechanism underlying the defective migration observed in Jak3^−/− lymphocytes remains elusive. Here, it is demonstrated for the first time, that Jak3 is required for the actin cytoskeleton reorganization in T lymphocytes responding to chemokines. It was found that Jak3 regulates actin polymerization by controlling cofilin inactivation in response to CCL21 and CXCL12. Interestingly, cofilin inactivation was not precluded in PTX- treated cells despite their impaired actin polymerization. Additionally, Jak3 was required for small GTPases Rac1 and RhoA activation, which are indispensable for acquisition of the migratory cell phenotype and the generation of a functional leading edge and uropod, respectively. This defect correlates with data obtained by time-lapse video-microscopy showing an incompetent uropod formation and impaired motility in Jak3-pharmacologically inhibited T lymphocytes. Our data support a new model in which Jak3 and heterotrimeric G proteins can use independent, but complementary, signaling pathways to regulate actin cytoskeleton dynamics during cell migration in response to chemokines.

Roflumilast N-oxide prevents cytokine secretion induced by cigarette smoke combined with LPS through JAK/STAT and ERK1/2 inhibition in airway epithelial cells

Cigarette smoke is a major cause of chronic obstructive pulmonary disease (COPD). Airway epithelial cells and macrophages are the first defense cells against cigarette smoke and these cells are an important source of pro-inflammatory cytokines. These cytokines play a role in progressive airflow limitation and chronic airways inflammation. Furthermore, the chronic colonization of airways by Gram-negative bacteria, contributes to the persistent airways inflammation and progression of COPD. The current study addressed the effects of cigarette smoke along with lipolysaccharide (LPS) in airway epithelial cells as a representative in vitro model of COPD exacerbations. Furthermore, we evaluated the effects of PDE4 inhibitor, the roflumilast N-oxide (RNO), in this experimental model. A549 cells were stimulated with cigarette smoke extract (CSE) alone (0.4% to 10%) or in combination with a low concentration of LPS (0.1 µg/ml) for 2 h or 24 h for measurement of chemokine protein and mRNAs and 5-120 min for protein phosphorylation. Cells were also pre-incubated with MAP kinases inhibitors and Prostaglandin E2 alone or combined with RNO, before the addition of CSE+LPS. Production of cytokines was determined by ELISA and protein phosphorylation by western blotting and phospho-kinase array. CSE did not induce production of IL-8/CXCL8 and Gro-α/CXCL1 from A549 cells, but increase production of CCL2/MCP-1. However the combination of LPS 0.1 µg/ml with CSE 2% or 4% induced an important production of these chemokines, that appears to be dependent of ERK1/2 and JAK/STAT pathways but did not require JNK and p38 pathways. Moreover, RNO associated with PGE2 reduced CSE+LPS-induced cytokine release, which can happen by occur through of ERK1/2 and JAK/STAT pathways. We report here an in vitro model that can reflect what happen in airway epithelial cells in COPD exacerbation. We also showed a new pathway where CSE+LPS can induce cytokine release from A549 cells, which is reduced by RNO.

Human β-defensin 3 induces STAT1 phosphorylation, tyrosine phosphatase activity, and cytokine synthesis in T cells

The AMP hBD-3 stimulates numerous immune effector functions in myeloid cells and keratinocytes, predominantly through the MAPK signaling cascade. In contrast, hBD-3 was reported to neutralize the activation of T cells by antagonizing MAPK signaling initiated by SDF-1α through CXCR4. With the use of complementary proteomic and immunochemical approaches, we investigated possible stimulatory effects of hBD-3 on T cells and demonstrate that hBD-3 induces STAT1 tyrosine phosphorylation within 5 min yet is unable to induce MAPK activation. Inclusion of a PTPase inhibitor increased hBD-3-induced phosphorylation dramatically, suggesting that hBD-3 also stimulates PTPase activity concurrently. The increase in PTPase activity was confirmed by demonstrating that hBD-3 suppresses IFN-γ-induced STAT1 tyrosine phosphorylation but not STAT1 serine and ERK1/2 threonine phosphorylation and stimulates the translocation of SHP-2 into the nucleus within 15 min. The signaling pathways initiated by hBD-3 may lead to the observed enhancement of distinct T cell effector functions during TCR activation, such as the increase in IL-2 and IL-10, but not IFN-γ secretion. Thus, hBD-3 initiates distinct lineage-specific signaling cascades in various cells involved in host defense and induces a concurrent tyrosine kinase and tyrosine phosphatase signaling cascade that may activate simultaneously the targeted T cells and inhibit their response to other immune mediators. Furthermore, these results suggest that this evolutionarily conserved peptide, which exhibits a broad spectrum of antimicrobial and immunomodulatory activities, serves to integrate innate and adaptive immunity.

CCR1-mediated STAT3 tyrosine phosphorylation and CXCL8 expression in THP-1 macrophage-like cells involve pertussis toxin-insensitive Gα(14/16) signaling and IL-6 release

Agonists of CCR1 contribute to hypersensitivity reactions and atherosclerotic lesions, possibly via the regulation of the transcription factor STAT3. CCR1 was demonstrated to use pertussis toxin-insensitive Gα(14/16) to stimulate phospholipase Cβ and NF-κB, whereas both Gα(14) and Gα(16) are also capable of activating STAT3. The coexpression of CCR1 and Gα(14/16) in human THP-1 macrophage-like cells suggests that CCR1 may use Gα(14/16) to induce STAT3 activation. In this study, we demonstrated that a CCR1 agonist, leukotactin-1 (CCL15), could indeed stimulate STAT3 Tyr(705) and Ser(727) phosphorylation via pertussis toxin-insensitive G proteins in PMA-differentiated THP-1 cells, human erythroleukemia cells, and HEK293 cells overexpressing CCR1 and Gα(14/16). The STAT3 Tyr(705) and Ser(727) phosphorylations were independent of each other and temporally distinct. Subcellular fractionation and confocal microscopy illustrated that Tyr(705)-phosphorylated STAT3 translocated to the nucleus, whereas Ser(727)-phosphorylated STAT3 was retained in the cytosol after CCR1/Gα(14) activation. CCL15 was capable of inducing IL-6 and IL-8 (CXCL8) production in both THP-1 macrophage-like cells and HEK293 cells overexpressing CCR1 and Gα(14/16). Neutralizing Ab to IL-6 inhibited CCL15-mediated STAT3 Tyr(705) phosphorylation, whereas inhibition of STAT3 activity abolished CCL15-activated CXCL8 release. The ability of CCR1 to signal through Gα(14/16) provides a linkage for CCL15 to regulate IL-6/STAT3-signaling cascades, leading to expression of CXCL8, a cytokine that is involved in inflammation and the rupture of atherosclerotic plaque.

Chemokine (C-C motif) receptor 2 mediates mast cell migration to abdominal aortic aneurysm lesions in mice

AIMS

Mast cells participate importantly in abdominal aortic aneurysms (AAAs) by releasing inflammatory cytokines to promote vascular cell protease expression and arterial wall remodelling. Mast cells accumulate in AAA lesions during disease progression, but the exact chemokines by which mast cells migrate to the site of vascular inflammation remain unknown. This study tested the hypothesis that mast cells use chemokine (C-C motif) receptor 2 (CCR2) for their accumulation in experimental mouse AAA lesions.

METHODS AND RESULTS

We generated mast cell and apolipoprotein E double-deficient (Apoe(-/-)Kit(W-sh/W-sh)) mice and found that they were protected from angiotensin II (Ang II) chronic infusion-induced AAAs compared with Apoe(-/-) littermates. Using bone-marrow derived mast cells (BMMC) from Apoe(-/-) mice and CCR2 double-deficient (Apoe(-/-)Ccr2(-/-)) mice, we demonstrated that Apoe(-/-)Kit(W-sh/W-sh) mice receiving BMMC from Apoe(-/-)Ccr2(-/-) mice, but not those from Apoe(-/-) mice, remained protected from AAA formation. Adoptive transfer of BMMC from Apoe(-/-) mice into Apoe(-/-)Kit(W-sh/W-sh) mice also increased lesion content of macrophages, T cells, and MHC class II-positive cells; there was also increased apoptosis, angiogenesis, cell proliferation, elastin fragmentation, and medial smooth muscle cell loss. In contrast, adoptive transfer of BMMC from Apoe(-/-)Ccr2(-/-) mice into Apoe(-/-)Kit(W-sh/W-sh) mice did not affect these variables.

CONCLUSIONS

The increased AAA formation and associated lesion characteristics in Apoe(-/-)Kit(W-sh/W-sh) mice after receiving BMMC from Apoe(-/-) mice, but not from Apoe(-/-)Ccr2(-/-) mice, suggests that mast cells use CCR2 as the chemokine receptor for their recruitment in Ang II-induced mouse AAA lesions.

CCR2 Antagonists for the Treatment of Diseases Associated with Inflammation

The CCR2 and MCP-1 pathway has become one of the most-studied chemokine systems for therapeutic use in inflammatory diseases and conditions. It plays a pivotal role in inflammatory diseases, especially those that are characterized by monocyte-rich infiltration. This chapter reviews the biology of CCR2 and MCP-1, and their roles in diseases and conditions related to inflammation such as rheumatoid arthritis, multiple sclerosis, asthma, obesity, type 2 diabetes, atherosclerosis, nephropathy, cancer, pulmonary fibrosis and pain. Intense drug-discovery efforts over the past 15 years have generated a large number of CCR2 antagonists in diverse structural classes. Mutagenesis studies have elucidated important residues on CCR2 that interact with many classes of these CCR2 antagonists. To facilitate understanding of CCR2 antagonist SAR, a simple pharmacophore model is used to summarize the large number of diverse chemical structures. The majority of published compounds are classified based on their central core structures using this model. Key SAR points in the published literature are briefly discussed for most of the series. Lead compounds in each chemical series are highlighted where information is available. The challenges in drug discovery and development of CCR2 antagonists are briefly discussed. Clinical candidates in various diseases in the public domain are summarized with a brief discussion about the clinical challenges.

Secondary cytotoxicity mediated by alveolar macrophages: a contribution to the total efficacy of nanoparticles in lung cancer therapy?

Local treatment of lung cancer using inhalable nanoparticles (NPs) is an emerging and promising treatment option. The aim of this study was to investigate the activation of alveolar macrophages by poly (isobutyl cyanoacrylate) (BIPCA) NPs and the consequences of this activation on H460 lung cancer cells. A methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay was used to determine the primary cytotoxicity, that is, the immediate and direct cytotoxicity of doxorubicin (DOX)-loaded NPs on both cell lines. Macrophages were then treated using EC(50) concentrations of different treatments and co-cultured in a two-compartment system with H460 lung cancer cells. These treatments included DOX solution, blank NPs, and DOX-loaded NPs. The results showed that alveolar macrophages exposed to blank or DOX-loaded NPs showed cytotoxicity against cancer cells after 8 and 24h; this behavior was not expressed by naïve macrophages or macrophages treated with DOX solution. Sample analysis indicated that macrophages have the ability to release back fragments of NPs that were previously phagocytized. Further investigations showed that NPs can induce an increase in the excretion of Th1 cytokines namely, monocytes chemoattractant protein-1 (MCP-1), macrophages inflammatory protein (MIP-1), tumor necrosis factor alpha (TNF-alpha), and interferon gamma (IFN-gamma). The Th1 cytokines released by the alveolar macrophages might explain the significant secondary cytotoxicity effect on H460 cancer cells. Secondary cytotoxicity mediated by macrophages might compliment the direct cytotoxic effect that NPs have on cancer cells.

Systemic MCP1/CCR2 blockade and leukocyte specific MCP1/CCR2 inhibition affect aortic aneurysm formation differently

OBJECTIVE

CCR2, the receptor for monocyte chemoattractant protein 1 (MCP1), is involved in atherosclerosis and abdominal aortic aneurysms (AAAs). Here, we explored the potential beneficial blockade of the MCP1/CCR2 pathway.

METHODS

We applied an AAA model in aging apolipoprotein E deficient mice with pre-existing atherosclerotic lesions. These mice were subjected to two therapeutic strategies. First, a dominant negative form of MCP1 was overexpressed in femoral muscles, resulting in circulating levels of MCP1-7ND (7ND), competing with native MCP1. In the second approach, bone marrow transplantation was performed using bone marrow cells that were infected with a lentiviral construct containing siRNA for CCR2, to specifically inhibit only leukocyte CCR2 expression.

RESULTS

Both strategies did not influence lesion size of the advanced atherosclerotic plaques. However, 7ND induced a more fibrous plaque phenotype. Yet, surprisingly a trend in increased number and severity of AAA was observed in the 7ND group. Smooth muscle cells in the aneurysm showed decreased phosphorylated signal transducer and activator of transcription five (STAT5, P<0.01) in the 7ND group, which is indicative for a decreased proliferative and migratory (wound healing) response. This presumably resulted in the increased AAA development. In contrast, siRNA-induced inhibition of CCR2 in leukocytes led to a significant inhibition in aneurysm formation. In conclusion, systemic inhibition of the MCP1/CCR2 pathway leads to a fibrous plaque phenotype in the advanced atherosclerotic lesions, but to potential adverse effects on AAA formation, implying that for a beneficial overall therapeutic approach, specific inhibitory targeting of leukocyte CCR2 will be essential.

Infrared A radiation influences the skin fibroblast transcriptome: mechanisms and consequences

Infrared A (IRA) radiation (760-1440 nm) is a major component of solar radiation and, similar to UVR, causes photoaging of human skin by increasing the expression of matrix metalloproteinase-1 in human skin fibroblasts. In this study, we assessed the IRA-induced transcriptome in primary human skin fibroblasts. Microarray analysis revealed 599 IRA-regulated transcripts. The IRA-induced transcriptome differed from changes known to be induced by UV. IRA-responsive genes include the categories extracellular matrix, calcium homeostasis, stress signaling, and apoptosis. Selected results were confirmed by real-time PCR experiments analyzing 13 genes representing these four categories. By means of chemical inhibitors of known signaling pathways, we showed that ERK1/2, the p38-, JNK-, PI3K/AKT-, STAT3-, and IL-6 as well as the calcium-mediated signaling pathways, are functionally involved in the IRA gene response and that a major part of it is triggered by mitochondrial and, to a lesser extent, non-mitochondrial production of reactive oxygen species. Our results identify IRA as an environmental factor with relevance for skin homeostasis and photoaging.

Monocyte chemotactic protein-1 regulates voltage-gated K+ channels and macrophage transmigration

Progressive human immunodeficiency virus (HIV)-1 infection and virus-induced neuroinflammatory responses effectuate monocyte-macrophage transmigration across the blood-brain barrier (BBB). A key factor in mediating these events is monocyte chemotactic protein-1 (MCP-1). Upregulated glial-derived MCP-1 in HIV-1-infected brain tissues generates a gradient for monocyte recruitment into the nervous system. We posit that the inter-relationships between MCP-1, voltage-gated ion channels, cell shape and volume, and cell mobility underlie monocyte transmigration across the BBB. In this regard, MCP-1 serves both as a chemoattractant and an inducer of monocyte-macrophage ion flux affecting cell shape and mobility. To address this hypothesis, MCP-1-treated bone marrow-derived macrophages (BMM) were analyzed for gene and protein expression, electrophysiology, and capacity to migrate across a laboratory constructed BBB. MCP-1 enhanced K+ channel gene (KCNA3) and channel protein expression. Electrophysiological studies revealed that MCP-1 increased outward K+ currents in a dose-dependent manner. In vitro studies demonstrated that MCP-1 increased BMM migration across an artificial BBB, and the MCP-1-induced BMM migration was blocked by tetraethylammonium, a voltage-gated K+ channel blocker. Together these data demonstrated that MCP-1 affects macrophage migratory movement through regulation of voltage-gated K+ channels and, as such, provides a novel therapeutic strategy for neuroAIDS.

Chemokine receptor CCR2 undergoes transportin1-dependent nuclear translocation

Chemokines (CCs) are small chemoattractant cytokines involved in a wide variety of biological and pathological processes. Released by cells in the milieu, and extracellular matrix and activating signalling cascades upon binding to specific G protein-coupled receptors (GPCRs), they trigger many cellular events. In various pathologies, CCs are directly responsible for excessive recruitment of leukocytes to inflammatory sites and recent studies using chemokine receptor (CCR) antagonists permitted these molecules to reach the market for medical use. While interaction of CCs with their receptors has been extensively documented, downstream GPCR signalling cascades triggered by CC are less well understood. Given the pivotal role of chemokine receptor 2 (CCR2) in monocyte recruitment, activation and differentiation and its implication in several autoimmune-inflammatory pathologies, we searched for potential new CCR2-interacting proteins by engineering a modified CCR2 that we used as bait. Herein, we show the direct interaction of CCR2 with transportin1 (TRN1), which we demonstrate is followed by CCR2 receptor internalization. Further characterization of this novel interaction revealed that TRN1-binding to CCR2 increased upon time in agonist treated cells and promotes its nuclear translocation in a TRN1-dependent manner. Finally, we provide evidence that following translocation, the receptor localizes at the outer edge of the nuclear envelope where it is finally released from TRN1.

Bleomycin treatment causes enhancement of virus replication in the lungs of SHIV-infected macaques

Pneumonia is a major complication of human immunodeficiency virus (HIV) pathogenesis but it develops only after prolonged infection. We used the macaque model to explore a hypothesis that the disease is a two-stage process, the first stage being establishment of the viral infection in the lung and the second being amplification of virus replication by host factors induced by chemical agents or opportunistic pathogens in the lung. Bleomycin, a chemical known to induce diffuse alveolar damage and pulmonary fibrosis with accumulation of macrophages and a rich T helper type 2 (Th2) cytokine environment, was inoculated intratracheally into five of eight SHIV 89.6P-infected macaques and into one uninfected macaque. Three additional simian HIV (SHIV)-infected macaques without bleomycin treatment served as untreated virus controls. Although none of the animals became clinically ill, bleomycin induced classical host responses in the lungs of all the treated, virus-infected macaques. There was enhanced production of the chemokine, monocyte chemotactic protein-1 (MCP-1), that had previously been shown to cause enhanced replication of the virus. Four of the five treated animals developed more productive SHIV infection in the lungs compared with the infected untreated animals. Enhanced virus replication was found primarily in infiltrating macrophages. Enhanced replication of the virus in the lungs was associated with host factors induced by the drug and supported the hypothesis for a two-stage process of pulmonary pathogenesis.

Fat accumulation with altered inflammation and regeneration in skeletal muscle of CCR2-/- mice following ischemic injury

Chemokines recruit inflammatory cells to sites of injury, but the role of the CC chemokine receptor 2 (CCR2) during regenerative processes following ischemia is poorly understood. We studied injury, inflammation, perfusion, capillary formation, monocyte chemotactic protein-1 (MCP-1) levels, muscle regeneration, fat accumulation, and transcription factor activation in hindlimb muscles of CCR2-/- and wild-type (WT) mice following femoral artery excision (FAE). In both groups, muscle injury and restoration of vascular perfusion were similar. Nevertheless, edema and neutrophil accumulation were significantly elevated in CCR2-/- compared with WT mice at day 1 post-FAE and fewer macrophages were present at day 3. MCP-1 levels in post-ischemic calf muscle of CCR2-/- animals were significantly elevated over baseline through 14 days post-FAE and were higher than WT mice at days 1, 7, and 14. In addition, CCR2-/- mice exhibited impaired muscle regeneration, decreased muscle fiber size, and increased intermuscular adipocytes with similar capillaries/mm(2) postinjury. Finally, the transcription factors, MyoD and signal transducers of and activators of transcription-3 (STAT3), were significantly increased above baseline but did not differ significantly between groups at any time point post-FAE. These findings suggest that increases in MCP-1, and possibly, MyoD and STAT3, may modulate molecular signaling in CCR2-/- mice during inflammatory and regenerative events. Furthermore, alterations in neutrophil and macrophage recruitment in CCR2-/- mice may critically alter the normal progression of downstream regenerative events in injured skeletal muscle and may direct myogenic precursor cells in the regenerating milieu toward an adipogenic phenotype.

CXCL12 Signaling Is Independent of Jak2 and Jak3

Janus kinases (Jaks) are a small family of cytoplasmic tyrosine kinases, critical for signaling by Type I and II cytokine receptors. The importance of Jaks in signaling by these receptors has been firmly established by analysis of mutant cell lines, the generation of Jak knock-out mice, and the identification of patients with Jak3 mutations. While a number of other ligands that do not bind Type I and II cytokine receptors have also been reported to activate Jaks, the requirement for Jaks in signaling by these receptors is less clear. Chemokines for example, which bind seven transmembrane receptors, have been reported to activate Jaks, and principally through the use of pharmacological inhibitors, it has been argued that Jaks are essential for chemokine signaling. In the present study, we focused on CXCR4, which binds the chemokine CXCL12 or stromal cell-derived factor-1, a chemokine that has been reported to activate Jak2 and Jak3. We found that the lack of Jak3 had no effect on CXCL12 signaling or chemotaxis nor did overexpression of wild-type versions of the kinase. Similarly, overexpression of wild-type or catalytically inactive Jak2 or "knocking-down" Jak2 expression using siRNA also had no effect. We also found that in primary lymphocytes, CXCL12 did not induce appreciable phosphorylation of any of the Jaks compared with cytokines for which these kinases are required. Additionally, little or no Stat (signal transducer and activator of transcription) phosphorylation was detected. Thus, we conclude that in contrast to previous reports, Jaks, especially Jak3, are unlikely to play an essential role in chemokine signaling.