CCL2 Knockdown Attenuates Inflammatory Response After Spinal Cord Injury Through the PI3K/Akt Signaling Pathway: Bioinformatics Analysis and Experimental Validation

Spinal cord injury (SCI) is a common clinical problem in orthopedics with a lack of effective treatments and drug targets. In the present study, we performed bioinformatic analysis of SCI datasets GSE464 and GSE45006 in the Gene Expression Omnibus (GEO) public database and experimentally validated CCL2 expression in an animal model of SCI. This was followed by stimulation of PC-12 cells using hydrogen peroxide to construct a cellular model of SCI. CCL2 expression was knocked down using small interfering RNA (si-CCL2), and PI3K signaling pathway inhibitors and activators were used to validate and observe the changes in downstream inflammation. Through data mining, we found that the inflammatory chemokine CCL2 and PI3K/Akt signaling pathways after SCI expression were significantly increased, and after peroxide stimulation of PC-12 cells with CCL2 knockdown, their downstream cellular inflammatory factor levels were decreased. The PI3K/Akt signaling pathway was blocked by PI3K inhibitors, and the downstream inflammatory response was suppressed. In contrast, when PI3K activators were used, the inflammatory response was enhanced, indicating that the CCL2-PI3K/Akt signaling pathway plays a key role in the regulation of the inflammatory response. This study revealed that the inflammatory chemokine CCL2 can regulate the inflammatory response of PC-12 cells through the PI3K/Akt signaling pathway, and blocking the expression of the inflammatory chemokine CCL2 may be a promising strategy for the treatment of secondary injury after SCI.

FNDC4 reduces inflammation, proliferation, invasion and migration of rheumatoid synovial cells by inhibiting CCL2/ERK signaling

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic joint inflammation. Fibronectin type III domain-containing protein 4 (FNDC4) is a secretory factor that can regulate inflammatory diseases. However, the role of FNDC4 in RA has not been reported so far.

METHODS

The expression of FNDC4 in synovial tissues of RA was analyzed by GEO database (GSE55235 dataset). Then, the expression of FNDC4 in RA fibroblast-like synoviocytes (RA-FLSs) was detected by RT-qPCR and western blot. After constructing FNDC4 overexpression plasmid, cell proliferation and apoptosis were detected. Wound healing and transwell assays were used to detect cell migration and invasion. Then we examined the expression of cytokines related to cell inflammation. Subsequently, the regulatory mechanism of FNDC4 was further discussed. We detected the expression of CCL2 and ERK signaling pathway related proteins downstream of FNDC4. Finally, the mechanism was discussed through the overexpression of FNDC4 and CCL2 and the addition of ERK pathway activator tBHQ.

RESULTS

GEO database showed that FNDC4 expression decreased in synovial tissues of RA. FNDC4 expression was also decreased in RA-FLSs. Overexpression of FNDC4 inhibited the proliferation, invasion and migration of RA-FLSs whereas promoted the cellapoptosis. Overexpression of FNDC4 inhibited the release of inflammatory factors in RA-FLSs. The regulatory effect of FNDC4 is achieved by inhibiting the CCL2/ERK signaling pathway.

CONCLUSION

FNDC4 reduces inflammation, proliferation, invasion and migration of RA-FLSs in RA by inhibiting CCL2/ERK signaling.

CCL2 chemokine inhibition primes the tumor vasculature for improved nanomedicine delivery and efficacy

Blood vessel functionality is crucial for efficient tumor-targeted drug delivery. Heterogeneous distribution and perfusion of angiogenic blood vessels contribute to suboptimal accumulation of (nano-) therapeutics in tumors and metastases. To attenuate pathological angiogenesis, an L-RNA aptamer inhibiting the CC motif chemokine ligand 2 (CCL2) was administered to mice bearing orthotopic 4T1 triple-negative breast cancer tumors. The effect of CCL2 inhibition on tumor blood vessel functionality and tumor-targeted drug delivery was evaluated via multimodal and multiscale optical imaging, employing fluorophore-labeled polymeric (10 nm) and liposomal (100 nm) nanocarriers. Anti-CCL2 treatment induced a dose-dependent anti-angiogenic effect, reflected by a decreased relative blood volume, increased blood vessel maturity and functionality, and reduced macrophage infiltration, accompanied by a shift in the polarization of tumor-associated macrophages (TAM) towards a less M2-like and more M1-like phenotype. In line with this, CCL2 inhibitor treatment improved the delivery of polymers and liposomes to tumors, and enhanced the antitumor efficacy of free and liposomal doxorubicin. Together, these findings demonstrate that blocking the CCL2-CCR2 axis modulates TAM infiltration and polarization, resulting in vascular normalization and improved tumor-targeted drug delivery.

IDO Regulates Macrophage Functions by Inhibiting the CCL2/CCR2 Signaling Pathway in Fungal Keratitis

PURPOSE

The aim of this study was to investigate the effects of indoleamine 2,3-dioxygenase (IDO) on macrophage polarization, phagocytosis, and killing through regulation of the CCL2/CCR2 signaling pathway in Aspergillus fumigatus keratitis.

METHODS

In vivo and in vitro experiments were conducted in mice and mouse peritoneal macrophages after infection with A. fumigatus . Clinical scoring, reverse transcription-polymerase chain reaction, and immunofluorescence staining were used to evaluate the fungal keratitis lesions, macrophage-related cytokines, and macrophage recruitment. The expression of CCL2 and CCR2 was detected by reverse transcription-polymerase chain reaction and western blot after pretreatment with or without an IDO inhibitor (1-MT). After pretreatment with 1-MT, a CCR2 antagonist, a CCL2 neutralizing antibody, an IDO agonist (IFNG), and recombinant CCL2 protein (CCL2), the flow cytometry and colony-forming unit counts were used to detect the polarization, phagocytosis, and killing function.

RESULTS

Compared with the control group, the infected eyes showed increased clinical scores, macrophage-related cytokine expression, and macrophage recruitment. 1-MT pretreatment increased the expression of CCL2 and CCR2 and the proportion of CD206+/CD86+ macrophages; macrophages polarized toward the M2 type, with enhanced killing function. CCR2 antagonists and CCL2 neutralizing antibodies reversed the effects of 1-MT. Compared with the infected group, IFNG pretreatment decreased the proportion of CD206+/CD86+ macrophages, and macrophages polarized toward the M1 type, with decreased phagocytosis and impaired killing function. CCL2 reversed the effect of IFNG.

CONCLUSIONS

IDO can promote the polarization of macrophages to the M1 type by blocking the CCL2/CCR2 signaling pathway, inhibiting the phagocytosis and killing function of macrophages, and mediating the protective immune role of A. fumigatus .

Ascorbic Acid vs Calcitriol in Influencing Monocyte Chemoattractant Protein-1, Nitric Oxide, Superoxide Dismutase, as Markers of Endothelial Dysfunction: In Vivo Study in Atherosclerosis Rat Model

Introduction

Ascorbic acid and calcitriol were frequently utilized in conjunction as therapy during the COVID-19 pandemic, and individuals with minor symptoms had notable improvements. There have been a few studies, often with conflicting findings, that examine the use of them for endothelium restoration and numerous clinical trial studies that failed to establish the efficacy. The aim of this study was to find the efficacy of ascorbic acid compared to calcitriol on the inflammatory markers monocyte chemoattractant protein-1 (MCP-1), nitric oxide (NO), and superoxide dismutase (SOD), as protective agents which play an important role in the early stages of atherosclerosis formation. This study was an experimental in vivo study.

Methods

The total of 24 male Rattus norvegicus strain Wistar rats were divided into 4 groups, namely: control/normal group (N), atherosclerosis group (DL) given atherogenic diet, atherosclerosis group given atherogenic diet and ascorbic acid (DLC), and atherosclerosis group given atherogenic diet and calcitriol (DLD) treatment for 30 days.

Results

Ascorbic acid and calcitriol treatment was significantly effective (P<0.05) in lowering expression of MCP-1 and increasing NO and SOD level. Calcitriol was superior to ascorbic acid in increasing SOD (P<0.05). There was no significant difference between ascorbic acid and calcitriol in decreasing MCP-1 and increasing NO (P>0.05).

Discussion

Both treatments could reduce MCP-1, and increase NO and SOD by increasing antioxidants. In this study calcitriol was superior to ascorbic acid in increasing SOD, but not NO and decreasing MCP-1. According to the theory, it was found that calcitriol through nuclear factor erythroid 2-related factor 2 (Nrf2) causes a direct increase in the amount of SOD. Nrf2 is an emerging regulator of cellular resistance to oxidants.

Conclusion

Ascorbic acid and calcitriol treatment was able to reduce MCP-1 and increase NO and SOD in atherosclerosis rat. Calcitriol was significantly superior in increasing SOD levels compared to ascorbic acid.

Adropin decreases endothelial monolayer permeability after cell-free hemoglobin exposure and reduces MCP-1-induced macrophage transmigration

BACKGROUND

Cell-free heme-containing proteins mediate endothelial injury in a variety of disease states including subarachnoid hemorrhage and sepsis by increasing endothelial permeability. Inflammatory cells are also attracted to sites of vascular injury by monocyte chemotactic protein 1 (MCP-1) and other chemokines. We have identified a novel peptide hormone, adropin, that protects against hemoglobin-induced endothelial permeability and MCP-1-induced macrophage migration.

METHODS

Human microvascular endothelial cells were exposed to cell-free hemoglobin (CFH) with and without adropin treatment before measuring monolayer permeability using a FITC-dextran tracer assay. mRNA and culture media were collected for molecular studies. We also assessed the effect of adropin on macrophage movement across the endothelial monolayer using an MCP-1-induced migration assay.

RESULTS

CFH exposure decreases adropin expression and increases paracellular permeability of human endothelial cells. Treating cells with synthetic adropin protects against the increased permeability observed during the natural injury progression. Cell viability was similar in all groups and Hmox1 expression was not affected by adropin treatment. MCP-1 potently induced macrophage migration across the endothelial monolayer and adropin treatment effectively reduced this phenomenon.

CONCLUSIONS

Endothelial injury is a hallmark of many disease states. Our results suggest that adropin treatment could be a valuable strategy in preventing heme-mediated endothelial injury and macrophage infiltration. Further investigation of adropin therapy in animal models and human tissue specimens is needed.

The enhancement of CCL2 and CCL5 by human bone marrow-derived mesenchymal stem/stromal cells might contribute to inflammatory suppression and axonal extension after spinal cord injury

Human bone marrow-derived mesenchymal stem/stromal cells (hMSCs) have shown potential in facilitating recovery from spinal cord injury (SCI) through communicating with microglia/macrophages (MG/MΦ). We here focused on chemokines as a candidate for the communication. Selected MG/MΦ-related chemokines were determined gene expression after SCI and further focused CCL2/CCR2 and CCL5/CCR5 to estimate role of the chemokines by hMSCs. Male C57/BL6 mice were subjected to spinal cord transection. Gene expression was assayed in the spinal cords following SCI for selected MG/MΦ-related chemokines and their receptors. hMSCs (5×10⁵ cells) were then transplanted into parenchyma of the spinal cord, and the expressions of the Ccl2/Ccr2 and Ccl5/Ccr5 axes, inflammation, MG/MΦ-polarization, and axonal regeneration were evaluated to measure the influence of the hMSCs. Finally, mouse CCL5 was injected into the spinal cords. Acute increases in gene expression after SCI were observed for most chemokines, including Ccl2; chronic increases were observed for Ccl5. CCL2⁺-cells merged with NeuN⁺-neurons. CCR2⁺ immunoreactivity was principally observed in Ly-6G⁺/iNOS⁺-granulocytes on postoperative day (pod) 1, and CCL5⁺ and CCR5⁺ immunoreactivity overlapped with NeuN⁺-neurons and F4/80⁺-MG/MΦ on pod 14. The hMSC transplantation enhanced Ccl2 and Ccl5 and improved locomotor activity. The hMSC implantation did not alter the number of Ly-6G⁺/CCR2⁺ but decreased Il1, Elane, and Mpo on pod 3. Conversely, hMSC transplantation increased expression of Zc3h12a (encodes MCP-1-induced protein) on pod 14. Moreover, hMSC increased the Aif1, and two alternatively activated macrophage (AAM)-related genes, Arg1 and Chil3 (Ym1), as well as axonal regenerative markers, Dpysl2 and Gap43. Gene expression indicative of AAM polarization and axonal regeneration were partially recovered by CCL5 injection. These results suggest that hMSC implantation increases Ccl2 and Ccl5, improves locomotor activity, enhances MG/MΦ polarization to AAM, and increases the gene expression of axonal regenerative markers. These functions of hMSCs might be partially mediated by the CCL2/CCR2 and CCL5/CCR5 axes.

Distinct release strategies are required to modulate macrophage phenotype in young versus aged animals

The role of innate immunity and macrophages in the host response to biomaterials has received renewed attention. A context-dependent spectrum of macrophage phenotypes are shown to affect tissue integration and performance of implanted biomaterials and medical devices. Recent studies by our group demonstrated that the host response in aged animals was characterized by delayed macrophage recruitment, differences in marker expression and a shifted pro-inflammatory (M1) response, associated with an unresolved host response in the long-term. The present work sought to study the effects of single and sequential cytokine delivery regimens in aged mice to restore delayed recruitment of macrophages and shift the inflammatory host response towards an M2-like phenotype, using MCP-1 (macrophage chemotactic protein-1) and IL-4 (interleukin-4), respectively. Implantation of cytokine-eluting implants showed a preserved response to MCP-1 in both young and aged animals, restoring delayed macrophage recruitment in aged mice. However, the response elicited by IL-4, sequential delivery of MCP-1/IL-4 and coating components was distinct in young versus aged mice. While single delivery of IL-4 did not counteract the high inflammatory response observed in aged mice, the sequential delivery of MCP-1/IL-4 was capable of restoring both recruitment and shifting the macrophage response towards an M2-like phenotype, associated with decreased implant scarring in the long-term. In young mice, sequential delivery was not as effective as IL-4 alone at promoting an M2-like response, but did result in a reduction of M1 macrophages and capsule deposition downstream. These results demonstrate that a proper understanding of patient/context-dependent biological responses are needed to design biomaterial-based therapies with improved outcomes in the setting of aging.

MCP-1 Feedback Loop Between Adipocytes and Mesenchymal Stromal Cells Causes Fat Accumulation and Contributes to Hematopoietic Stem Cell Rarefaction in the Bone Marrow of Patients With Diabetes

Fat accumulates in bone marrow (BM) of patients with diabetes. In this study, we investigated the mechanisms and consequences of this phenomenon. BM mesenchymal stromal cells (BM-MSCs) from patients with type 2 diabetes (T2D) constitutively express adipogenic markers and robustly differentiate into adipocytes (ADs) upon in vitro induction as compared with BM-MSCs from subjects without diabetes. Moreover, BM-ADs from subjects with T2D (T2D BM-ADs) paracrinally stimulate a transcriptional adipogenic program in BM-MSCs. Antagonism of MCP-1, a chemokine pivotally expressed in T2D BM-ADs, prevented the T2D BM-AD secretome from converting BM-MSCs into ADs. Mechanistic validation of human data was next performed in an obese T2D mouse model. Systemic antagonism of MCP-1 improved metabolic control, reduced BM fat, and increased osteocyte density. It also indirectly re-established the abundance of long-term versus short-term hematopoietic stem cells. We reveal a diabetic feedback loop in which 1) BM-MSCs are constitutively inclined to make ADs, and 2) mature BM-ADs, via secreted MCP-1, relentlessly fuel BM-MSC determination into new fat. Pharmacological inhibition of MCP-1 signaling can contrast this vicious cycle, restoring, at least in part, the balance between adipogenesis and hematopoiesis in BM from subjects with T2D.

CCL2 Induces the Production of β2 Adrenergic Receptors and Modifies Astrocytic Responses to Noradrenaline

The decline in brain noradrenaline levels is associated with the progression of certain neurodegenerative diseases. This seems to be due, at least in part, to the ability of noradrenaline to limit glial activation and to reduce the damage associated with it. Our previous studies of the mechanisms involved in this process indicate that noradrenaline induces the production of the chemokine CCL2 in astrocytes. While CCL2 can protect neurons against certain injuries, its overproduction has also proven to be harmful and to prevent noradrenaline neuroprotective effects. Therefore, in this study, we analyze if the modifications caused to astrocytes by an excessive production of CCL2 may alter their response to noradrenaline. Using primary cultures of rat cortical astrocytes, we observed that CCL2 enhances the production of beta 2 adrenergic receptors in these cells. While this potentiates noradrenaline signaling through cAMP, the activation of the transcription factor CREB is inhibited by CCL2. Furthermore, although CCL2 potentiates noradrenaline induction of glycogenolysis, this does not translate into an augmented release of lactate, one of the processes through which astrocytes help support neurons. Additionally, other neuroprotective actions of noradrenaline, such as the production of brain derived neurotrophic factor and the inhibition of the inducible nitric oxide synthase in astrocytes were modified by CCL2. These data suggest that some of the central nervous system alterations related to CCL2 could be due to its effects on adrenergic receptors and its interference with noradrenaline signaling.

Tumor-associated macrophages (TAMs) depend on ZEB1 for their cancer-promoting roles

Accumulation of tumor-associated macrophages (TAMs) associates with malignant progression in cancer. However, the mechanisms that drive the pro-tumor functions of TAMs are not fully understood. ZEB1 is best known for driving an epithelial-to-mesenchymal transition (EMT) in cancer cells to promote tumor progression. However, a role for ZEB1 in macrophages and TAMs has not been studied. Here we describe that TAMs require ZEB1 for their tumor-promoting and chemotherapy resistance functions in a mouse model of ovarian cancer. Only TAMs that expressed full levels of Zeb1 accelerated tumor growth. Mechanistically, ZEB1 expression in TAMs induced their polarization toward an F4/80low pro-tumor phenotype, including direct activation of Ccr2 In turn, expression of ZEB1 by TAMs induced Ccl2, Cd74, and a mesenchymal/stem-like phenotype in cancer cells. In human ovarian carcinomas, TAM infiltration and CCR2 expression correlated with ZEB1 in tumor cells, where along with CCL2 and CD74 determined poorer prognosis. Importantly, ZEB1 in TAMs was a factor of poorer survival in human ovarian carcinomas. These data establish ZEB1 as a key factor in the tumor microenvironment and for maintaining TAMs' tumor-promoting functions.

Monocyte Chemoattractant Protein 1-Induced Monocyte Infiltration Produces Angiogenesis but Not Arteriogenesis in Chronically Infarcted Myocardium

Background: Monocyte chemoattractant protein 1 (MCP-1) stimulates the invasion of monocytes into ischemic tissue with concomitant adhesion to endothelial cells. Monocyte stimulation has been shown to be involved in the induction of arteriogenesis, which is the development of functional arterioles resulting in improvement of perfusion. However, angiogenesis (newly developed capillaries contribute to improved tissue perfusion) in several models has not resulted in any improvement in blood flow.

Objective: The effects of MCP-1 on potential angiogenesis and arteriogenesis as well as changes in left ventricular function were tested in a chronic infarct model in rat hearts.

Methods: Anesthetized rats were subjected to open-chest ligation of the left coronary artery with subsequent myocardial infarction. After 6 weeks, animals were randomized to receive either MCP-1 (3 µL in 0.15 mL NaCl, group 1, n = 9) or saline (0.15 mL, group 2, n = 9), which was injected into the myocardium at the border zones of the infarcts. For assessment of left ventricular dimensions and global cardiac function, transthoracic two-dimensional echocardiography was performed at baseline, 6 weeks after myocardial infarction, and 4 weeks after MCP-1 or saline injection, by use of a 12-MHz pediatric transducer. For light microscopic analysis, myocardial tissue was stained with Elastica-van-Giesson and von Willebrand factor for blood vessels and endothelial cells, respectively. In a subset of animals, hearts were excised 24 hours after MCP-1 administration (n = 4) or saline administration (n = 4) for assessment of monocyte infiltration by immunohistologic staining of the CD31 antigen.

Results: Left ventricular dimensions and ejection fraction changed after coronary occlusion (from 60.4% ± 2.85% to 24.8% ± 5.01% ejection fraction in group 1, and from 58.4% ±2.06% to 26.3% ± 4.3% ejection fraction in group 2 at 6 weeks, P < .005) without any further change 4 weeks after treatment (ejection fraction in group 1, 26.3% ± 2.7%, ejection fraction in group 2, 25.0% ± 5.18%). The MCP-1 group resulted in 390.6 ± 10.36 endothelial cells compared with 285.2 ± 13.56 in group 2 ( P < .005) at the injection site. Monocyte infiltration was observed at the MCP-1 injection site with an increase in capillary growth (angiogenesis). However, there was no difference in the number of arteriolar structures between animals treated with MCP-1 and saline animals (group 1, 19.0 ± 1.52 vs group 2,16.4 ± 0.68, P > .05).

Conclusion: A single intramyocardial injection of MCP-1 into the infarct border zone resulted in neo-angiogenesis and monocyte infiltration but not arteriogenesis in the rat heart. There was no functional change of chronically infarcted myocardium in the present model.

[INFLUENCE OF 29-40 AND 65-76 MCP-1 FRAGMENTS ON MYOCARDIUM MORPHOLOGY IN RATS AFTER T9CTHFMIA-R'FPFRFTTON]

Monocyte chemotactic protein-1 (MCP-1) is a chemokine that stimulates monocytes and macrophage migration into the sites of acute of chronic inflammation. Our study shows morphological changes in ischemic myocardium followed by the administration of two synthetic structural fragments of MCP-1 that are monocyte/macrophage migration inductor peptide IX and peptide X an inhibitor. Results show that peptides can change time points of the inflammatory response in myocardium. Peptide IX administration leads to increased and accelerated inflammatory response, i. e. attracts an additional number of monocytes and macrophages into the inflammatory focus. The introduction of the peptide X observed prolonged inflammatory process with the overall gain signs of myocardial damage.

Adipocyte-derived monocyte chemotactic protein-1 (MCP-1) promotes prostate cancer progression through the induction of MMP-2 activity

BACKGROUND

Obesity is known to be associated with prostate cancer development and progression, but the detailed mechanism is not clear. Monocyte chemotactic protein-1 (MCP-1) is secreted from cancer cells, stromal cells, and adipocytes, and it is involved in prostate cancer progression. Here we investigated the biological role of MCP-1 secreted from adipocytes for prostate cancer cells.

METHODS

Human pre-adipocytes (HPAds) were cultured and differentiated to mature adipocytes. Conditioned medium (CM) from HPAd cells was obtained using phenol red-free RPMI1640 medium. We performed a cytokine membrane array analysis to detect cytokines in the CM. To characterize the physiological function of MCP-1 in the CM, we performed an MTT-assay, a wound-healing and invasion assay with anti-MCP-1 antibody using three prostate cancer cell lines: DU145, LNCaP, and PC-3. Matrix metalloproteinase (MMP)-2 and MMP-9 activities were evaluated by gelatin zymography. A qPCR and Western blotting were used to examine the mRNA and protein expression levels of MMP-2.

RESULTS

The cytokine membrane array of the CM showed a strong signal of MCP-1compared to the control medium, and we thus focused our attention on MCP-1 in the CM. The CM up-regulated the cancer cell proliferation, and the neutralization by anti-MCP-1 antibody inhibited the proliferative effect of the prostate cancer cell lines. The CM greatly increased the invasive activity in the prostate cancer cell lines, and anti-MCP-1 antibody decreased the invasiveness. Gelatin zymography revealed that the CM markedly enhanced the enzymatic activity of MMP-2, and anti-MCP-1 antibody down-regulated its effect. MMP-2 mRNA expression was undetected and the MMP-2 protein level was unchanged between the control medium and CM in DU145 cells.

CONCLUSIONS

MCP-1 from adipocytes enhances the growth and invasion activity of prostate cancer cells. The inhibition of MCP-1 derived from adipocytes might be an effective treatment for prostate cancer.

The chemokine CCL5 induces selective migration of bovine classical monocytes and drives their differentiation into LPS-hyporesponsive macrophages in vitro

Human and mouse studies indicate distinct roles of selected chemokines for monocyte subset attraction. We therefore analyzed the still unknown sensitivity and response of bovine monocyte subsets toward two monocyte-attracting chemokines (CCL2, CCL5). Only CCL5 induced a significant Ca(2+)influx and migration response in bovine monocytes, with classical and intermediate monocytes being significantly stimulated and attracted compared to nonclassical monocytes. The presence of CCL5 during in vitro macrophage differentiation did not alter their capacity to phagocytize or to generate reactive oxygen species upon stimulation with E. coli. However, macrophages differentiated in the presence of CCL5 displayed an altered phenotype with significantly less expressed CD14 and MHC class II molecules, whereas CD16 was upregulated. Moreover, CCL5-differentiated macrophages displayed a reduced upregulation of CXCL8, ARG1, IL6 and IL10 mRNA. Taken together, CCL5 but not CCL2 mainly attract bovine classical monocytes and promote their differentiation into LPS-hypo-responsive macrophages.

Malarial pigment hemozoin impairs chemotactic motility and transendothelial migration of monocytes via 4-hydroxynonenal

Natural hemozoin, nHZ, is avidly phagocytosed in vivo and in vitro by human monocytes. The persistence of the undigested β-hematin core of nHZ in the phagocyte lysosome for long periods of time modifies several cellular immune functions. Here we show that nHZ phagocytosis by human primary monocytes severely impaired their chemotactic motility toward MCP-1, TNF, and FMLP, by approximately 80% each, and their diapedesis across a confluent human umbilical vein endothelial cell layer toward MCP-1 by 45±5%. No inhibition was observed with latex-fed or unfed monocytes. Microscopic inspection revealed polarization defects in nHZ-fed monocytes due to irregular actin polymerization. Phagocytosed nHZ catalyzes the peroxidation of polyunsaturated fatty acids and generation of the highly reactive derivative 4-hydroxynonenal (4-HNE). Similar to nHZ phagocytosis, the exposure of monocytes to in vivo-compatible 4-HNE concentrations inhibited cell motility in both the presence and the absence of chemotactic stimuli, suggesting severe impairment of cytoskeleton dynamics. Consequently, 4-HNE conjugates with the cytoskeleton proteins β-actin and coronin-1A were immunochemically identified in nHZ-fed monocytes and mass spectrometrically localized in domains of protein-protein interactions involved in cytoskeleton reorganization and cell motility. The molecular and functional modifications of actin and coronin by nHZ/4-HNE may also explain impaired phagocytosis, another motility-dependent process previously described in nHZ-fed monocytes. Further studies will show whether impaired monocyte motility may contribute to the immunodepression and the frequent occurrence of secondary infections observed in malaria patients.

Pro-inflammatory chemokine CCL2 (MCP-1) promotes healing in diabetic wounds by restoring the macrophage response

Prior studies suggest that the impaired healing seen in diabetic wounds derives from a state of persistent hyper-inflammation characterized by harmful increases in inflammatory leukocytes including macrophages. However, such studies have focused on wounds at later time points (day 10 or older), and very little attention has been given to the dynamics of macrophage responses in diabetic wounds early after injury. Given the importance of macrophages for the process of healing, we studied the dynamics of macrophage response during early and late phases of healing in diabetic wounds. Here, we report that early after injury, the diabetic wound exhibits a significant delay in macrophage infiltration. The delay in the macrophage response in diabetic wounds results from reduced Chemokine (C-C motif) ligand 2 (CCL2) expression. Importantly, one-time treatment with chemoattractant CCL2 significantly stimulated healing in diabetic wounds by restoring the macrophage response. Our data demonstrate that, rather than a hyper-inflammatory state; the early diabetic wound exhibits a paradoxical and damaging decrease in essential macrophage response. Our studies suggest that the restoration of the proper kinetics of macrophage response may be able to jumpstart subsequent healing stages. CCL2 chemokine-based therapy may be an attractive strategy to promote healing in diabetic wounds.

Monocyte chemotactic protein 1 (MCP-1) modulates pro-survival signaling to promote progression of head and neck squamous cell carcinoma

Background

Monocyte chemotactic protein-1 (MCP-1) recruits monocytes and macrophages to inflammation sites, and inflammatory infiltration correlates with the progression of head and neck squamous cell carcinoma (HNSCC). This study aims to determine whether MCP-1 expression is related to HNSCC malignancy and patient survival. We also investigated the relationship between MCP-1 expression and the phosphorylation state of the pro-survival pathway factors Akt, ERK, and STAT3.

Methods

Expression of MCP-1 and related proteins in HNSCC cell lines was investigated using western blotting. HNSCC patients (34) without distant metastasis at diagnosis were recruited for tissue specimen evaluation of MCP-1 expression and clinical outcomes. The relationship between MCP-1 expression and survival was evaluated using the Cox proportional hazard model with stepwise selection.

Results

High-grade HNSCC cell lines were found to have higher levels of active Akt, ERK, and/or STAT3 than did lower grade cell lines under serum-free condition. OCSL, the most malignant cell line, had the highest level of endogenous MCP-1. Administration of exogenous recombinant MCP-1 increased phosphorylation of Akt, ERK, and STAT3 in a dose- and time-dependent manner and increased cellular resistance to serum starvation. Inhibition of Akt, ERK, or STAT3 reduced cell growth and caused cell death. Long-term survival of HNSCC patients was negatively associated with the histological intensity of MCP-1, implicating MCP-1 as a potential prognostic marker for HNSCC.

Conclusions

These results suggest that overexpressed MCP-1 in cancer cells may promote HNSCC progression through upregulating pro-survival signaling pathways. High cellular MCP-1 expression is related to poor overall survival rate in HNSCC patients.

[MCPIP1 mediates MCP-1-induced vascular smooth muscle cell proliferation]

The aim of the present study is to investigate whether monocyte chemotactic protein-1 (MCP-1)-induced vascular smooth muscle cell (VSMC) proliferation is mediated via monocyte chemotactic protein-1 induced protein-1 (MCPIP1). MCPIP1 expressions in cultured VSMC were detected by real-time PCR and Western blot following MCP-1 incubation. After MCPIP1 was silenced by siRNA, cell number was counted by hemocytometer, VSMC activity was analyzed by CCK-8 kit, percentage of DNA synthesis was detected by EdU kit, percentage of S phase cell numbers were measured by flow cytometry, and c-fos mRNA expression induced by MCP-1 or platelet-derived growth factor (PDGF) was detected by real-time PCR. The results showed MCP-1 increased MCPIP1 mRNA and up-regulated MCPIP1 protein expression in dose- and time-dependent manners. Cell counts, cellular activity, the percentage of DNA synthesis, and the percentage of S phase cell numbers were remarkably decreased in MCPIP1 siRNA group, compared with those in MCP-1 group. The enhancing effect of MCP-1 or PDGF on c-fos mRNA expression was inhibited by MCPIP1 siRNA. These results suggest that MCP-1-induced VSMC proliferation is mediated via MCPIP1, and the underlying mechanism may involve c-fos expression up-regulation.

Mechanisms of HIV entry into the CNS: increased sensitivity of HIV infected CD14+CD16+ monocytes to CCL2 and key roles of CCR2, JAM-A, and ALCAM in diapedesis

As HIV infected individuals live longer, the prevalence of HIV associated neurocognitive disorders is increasing, despite successful antiretroviral therapy. CD14(+)CD16(+) monocytes are critical to the neuropathogenesis of HIV as they promote viral seeding of the brain and establish neuroinflammation. The mechanisms by which HIV infected and uninfected monocytes cross the blood brain barrier and enter the central nervous system are not fully understood. We determined that HIV infection of CD14(+)CD16(+) monocytes resulted in their highly increased transmigration across the blood brain barrier in response to CCL2 as compared to uninfected cells, which did not occur in the absence of the chemokine. This exuberant transmigration of HIV infected monocytes was due, at least in part, to increased CCR2 and significantly heightened sensitivity to CCL2. The entry of HIV infected and uninfected CD14(+)CD16(+) monocytes into the brain was facilitated by significantly increased surface JAM-A, ALCAM, CD99, and PECAM-1, as compared to CD14(+) cells that are CD16 negative. Upon HIV infection, there was an additional increase in surface JAM-A and ALCAM on CD14(+)CD16(+) monocytes isolated from some individuals. Antibodies to ALCAM and JAM-A inhibited the transmigration of both HIV infected and uninfected CD14(+)CD16(+) monocytes across the BBB, demonstrating their importance in facilitating monocyte transmigration and entry into the brain parenchyma. Targeting CCR2, JAM-A, and ALCAM present on CD14(+)CD16(+) monocytes that preferentially infiltrate the CNS represents a therapeutic strategy to reduce viral seeding of the brain as well as the ongoing neuroinflammation that occurs during HIV pathogenesis.

Human chemokines as antimicrobial peptides with direct parasiticidal effect on Leishmania mexicana in vitro

Chemokines and chemokine receptor-mediated effects are important mediators of the immunological response and cure in human leishmaniasis. However, in addition to their signalling properties for leukocytes, many chemokines have also been shown to act directly as antimicrobial peptides on bacteria and fungi. We screened ten human chemokines (CXCL2, CXCL6, CXCL8, CXCL9, CXCL10, CCL2, CCL3, CCL20, CCL27, CCL28) for antimicrobial effects on the promastigote form of the protozoan parasite Leishmania mexicana, and observed direct parasiticidal effects of several, CCL28 being the most potent. Damage to the plasma membrane integrity could be visualised by entrance of propidium iodide, as measured with flow cytometry, and by scanning electron microscopy, which showed morphological changes and aggregation of cells. The findings were in concordance with parasiticidal activity, measured by decreased mitochondrial activity in an MTT-assay. This is the first report of direct antimicrobial activity by chemokines on parasites. This component of immunity against Leishmania parasites identified here warrants further investigation that might lead to new insight in the mechanisms of human infection and/or new therapeutic approaches.

The therapeutic role of monocyte chemoattractant protein-1 in a renal tissue engineering strategy for diabetic patients

In this study we aim to boost the functional output of the intra-kidney islet transplantation for diabetic patients using a tissue engineered polymeric scaffold. This highly porous electrospun scaffold featured randomly distributed fibers composed of polycaprolactone (PCL) and poliglecaprone (PGC). It successfully sustained murine islets in vitro for up to 4 weeks without detected cytotoxicity. The in vivo study showed that the islet population proliferated by 89% within 12 weeks when they were delivered by the scaffold but only 18% if freely injected. Correspondingly, the islet population delivered by the scaffold unleashed a greater capability to produce insulin that in turn further drove down the blood glucose within 12 weeks after the surgery. Islets delivered by the scaffold most effectively prevented diabetic deterioration of kidney as evidenced by the lack of a kidney or glomerular enlargement and physiological levels of creatinine, urea nitrogen and albumin through week 12 after the surgery. Unlike traditional wisdom in diabetic research, the mechanistic study suggested that monocytes chemoattractant protein-1 (MCP-1) was responsible for the improved preservation of renal functions. This study revealed a therapeutic role of MCP-1 in rescuing kidneys in diabetic patients, which can be integrated into a tissue engineered scaffold to simultaneously preserved renal functions and islet transplantation efficacy. Also, this study affords a simple yet effective solution to improve the clinical output of islet transplantation.

Differential regulation of CD4+ T cell adhesion to cerebral microvascular endothelium by the β-chemokines CCL2 and CCL3

In Multiple sclerosis (MS), circulating lymphocytes cross the blood–brain barrier (BBB) and accumulate at sites of antigenic challenge. This process depends on specific interactions between lymphocytes and cerebral microvascular endothelium that involve endothelial activation by cytokines and the presence of chemokines. Chemokines play a key role in the orchestration of immune responses, acting both as chemoattractants and activators of leukocyte subsets. In the present study, we investigated the effects of the β-chemokines, CCL2 and CCL3, on the adhesion of CD4+ T cell subsets to human brain microvessel endothelial cells (HBMEC). Chemokines added to the lower compartment of a two-chamber chemotaxis system under confluent resting or cytokine-activated HBMEC, diffused through the culture substrate and bound to the basal surface of HBMEC. The low rate of adhesion of naïve, resting and memory CD4+ T cells to resting HBMEC was significantly upregulated following treatment of HBMEC with TNF-α and IFN-γ. Recently activated CD4+ T cells readily adhered to resting monolayers. Concentration gradients of CCL2 upregulated the adhesion of activated CD4+ T cells to cytokine treated but not resting HBMEC. The presence of CCL3 in the lower chamber increased the adhesion of memory T cells to both unstimulated and cytokine-treated HBMEC. These findings emphasize the importance of brain endothelial cell activation and the role of CCL2 and CCL3 in regulating the adhesion of CD4+ T cell subsets to BBB endothelium, thus contributing to the specificity of immune responses in MS.

Redox regulation of MAPK phosphatase 1 controls monocyte migration and macrophage recruitment

Monocytic adhesion and chemotaxis are regulated by MAPK pathways, which in turn are controlled by redox-sensitive MAPK phosphatases (MKPs). We recently reported that metabolic disorders prime monocytes for enhanced recruitment into vascular lesions by increasing monocytes' responsiveness to chemoattractants. However, the molecular details of this proatherogenic mechanism were not known. Here we show that monocyte priming results in the S-glutathionylation and subsequent inactivation and degradation of MKP-1. Chronic exposure of human THP-1 monocytes to diabetic conditions resulted in the loss of MKP-1 protein levels, the hyperactivation of ERK and p38 in response to monocyte chemoattractant protein-1 (MCP-1), and increased monocyte adhesion and chemotaxis. Knockdown of MKP-1 mimicked the priming effects of metabolic stress, whereas MKP-1 overexpression blunted both MAPK activation and monocyte adhesion and migration induced by MCP-1. Metabolic stress promoted the S-glutathionylation of MKP-1, targeting MKP-1 for proteasomal degradation. Preventing MKP-1 S-glutathionylation in metabolically stressed monocytes by overexpressing glutaredoxin 1 protected MKP-1 from degradation and normalized monocyte adhesion and chemotaxis in response to MCP-1. Blood monocytes isolated from diabetic mice showed a 55% reduction in MKP-1 activity compared with nondiabetic mice. Hematopoietic MKP-1 deficiency in atherosclerosis-prone mice mimicked monocyte priming and dysfunction associated with metabolic disorders, increased monocyte chemotaxis in vivo, and accelerated atherosclerotic lesion formation. In conclusion, we identified MKP-1 as a central redox-sensitive regulator of monocyte adhesion and migration and showed that the loss of MKP-1 activity is a critical step in monocyte priming and the metabolic stress-induced conversion of blood monocytes into a proatherogenic phenotype.

Targeting the leukocyte activation cascade: getting to the site of inflammation using microfabricated assays

This paper describes the use of microfabricated devices to study the leukocyte activation cascade (LAC). The devices consist of microchannels fabricated in polydimethylsiloxane using soft lithography. Microfluidics, used to generate physiologically relevant levels of shear flow, was achieved by the simple attachment of a syringe pump. Microchannel surfaces were modified by self-assembled monolayer (SAM) chemistries. The devices were adapted to standard 96-well tissue culture format with microchannels that could accommodate either a monolayer of endothelial cells or a SAM with immobilized chemokines. Chemotaxis was performed using linear gradients of chemokine set in a 3D matrix. Using this approach, we demonstrated robust chemotaxis of primary human leukocytes (PHLs) in response to a gradient of the chemokine CCL2. Rolling and adhesion assays performed under shear flow demonstrated that leukocyte recruitment to the substrate was highly sensitive to both biological and physical forces. CCL2 and CXCL12 treatment of PHLs dose dependently increased activation and adhesion. These actions could be inhibited by the use of peptide or small molecule antagonists. These devices provide a robust platform to perform LAC assays under in vivo-like conditions.

Cytotoxic T lymphocyte trafficking and survival in an augmented fibrin matrix carrier

Cell-based therapies have intriguing potential for the treatment of a variety of neurological disorders. One such example is genetically engineered cytotoxic T lymphocytes (CTLs) that are being investigated in brain tumor clinical trials. The development of methods for CTL delivery is critical to their use in the laboratory and clinical setting. In our study, we determined whether CTLs can migrate through fibrin matrices and if their migration, survival, and function could be modulated by adding chemokines to the matrix. Our results indicated that CTLs can freely migrate through fibrin matrices. As expected, the addition of the monocyte chemotactic protein-1 (MCP-1), also known as chemokine C-C motif ligand 2 (CCL2), to the surrounding media increased egress of the CTLs out of the fibrin clot. Interleukin (IL) -2 and/or IL-15 embedded in the matrix enhanced T cell survival and further promoted T cell migration. The interleukin-13 receptor alpha 2 specific (IL-13R alpha2) T cells that traveled out of the fibrin clot retained the capacity to kill U251 glioma cells. In summary, CTLs can survive and migrate robustly in fibrin matrices. These processes can be influenced by modification of matrix constituents. We conclude that fibrin matrices may be suitable T cell carriers and can be used to facilitate understanding of T cell interaction with the surrounding microenvironment.

Contractile activity of human skeletal muscle cells prevents insulin resistance by inhibiting pro-inflammatory signalling pathways

AIMS/HYPOTHESIS

Obesity is closely associated with muscle insulin resistance and is a major risk factor for the pathogenesis of type 2 diabetes. Regular physical activity not only prevents obesity, but also considerably improves insulin sensitivity and skeletal muscle metabolism. We sought to establish and characterise an in vitro model of human skeletal muscle contraction, with a view to directly studying the signalling pathways and mechanisms that are involved in the beneficial effects of muscle activity.

METHODS

Contracting human skeletal muscle cell cultures were established by applying electrical pulse stimulation. To induce insulin resistance, skeletal muscle cells were incubated with human adipocyte-derived conditioned medium, monocyte chemotactic protein (MCP)-1 and chemerin.

RESULTS

Similarly to in exercising skeletal muscle in vivo, electrical pulse stimulation induced contractile activity in human skeletal muscle cells, combined with the formation of sarcomeres, activation of AMP-activated protein kinase (AMPK) and increased IL-6 secretion. Insulin-stimulated glucose uptake was substantially elevated in contracting cells compared with control. The incubation of skeletal muscle cells with adipocyte-conditioned media, chemerin and MCP-1 significantly reduced the insulin-stimulated phosphorylation of Akt. This effect was abrogated by concomitant pulse stimulation of the cells. Additionally, pro-inflammatory signalling by adipocyte-derived factors was completely prevented by electrical pulse stimulation of the myotubes.

CONCLUSIONS/INTERPRETATION

We showed that the effects of electrical pulse stimulation on skeletal muscle cells were similar to the effect of exercise on skeletal muscle in vivo in terms of enhanced AMPK activation and IL-6 secretion. In our model, muscle contractile activity eliminates insulin resistance by blocking pro-inflammatory signalling pathways. This novel model therefore provides a unique tool for investigating the molecular mechanisms that mediate the beneficial effects of muscle contraction.

Down-modulation of TNFSF15 in ovarian cancer by VEGF and MCP-1 is a pre-requisite for tumor neovascularization

Persistent inflammation and neovascularization are critical to cancer development. In addition to upregulation of positive control mechanisms such as overexpression of angiogenic and inflammatory factors in the cancer microenvironment, loss of otherwise normally functioning negative control mechanisms is likely to be an important attribute. Insights into the down-modulation of such negative control mechanisms remain largely unclear, however. We show here that tumor necrosis factor superfamily-15 (TNFSF15), an endogenous inhibitor of neovascularization, is a critical component of the negative control mechanism that operates in normal ovary but is missing in ovarian cancer. We show in clinical settings that TNFSF15 is present prominently in the vasculature of normal ovary but diminishes in ovarian cancer as the disease progresses. Vascular endothelial growth factor (VEGF) produced by cancer cells and monocyte chemotactic protein-1 (MCP-1) produced mainly by tumor-infiltrating macrophages and regulatory T cells effectively inhibits TNFSF15 production by endothelial cells in vitro. Using a mouse syngeneic tumor model, we demonstrate that silencing TNFSF15 by topical shRNA treatments prior to and following mouse ovarian cancer ID8 cell inoculation greatly facilitates angiogenesis and tumor growth, whereas systemic application of recombinant TNFSF15 inhibits angiogenesis and tumor growth. Our findings indicate that downregulation of TNFSF15 by cancer cells and tumor infiltrating macrophages and lymphocytes is a pre-requisite for tumor neovascularization.

Tumour tissue microenvironment can inhibit dendritic cell maturation in colorectal cancer

Inflammatory mediators in the tumour microenvironment promote tumour growth, vascular development and enable evasion of anti-tumour immune responses, by disabling infiltrating dendritic cells. However, the constituents of the tumour microenvironment that directly influence dendritic cell maturation and function are not well characterised. Our aim was to identify tumour-associated inflammatory mediators which influence the function of dendritic cells. Tumour conditioned media obtained from cultured colorectal tumour explant tissue contained high levels of the chemokines CCL2, CXCL1, CXCL5 in addition to VEGF. Pre-treatment of monocyte derived dendritic cells with this tumour conditioned media inhibited the up-regulation of CD86, CD83, CD54 and HLA-DR in response to LPS, enhancing IL-10 while reducing IL-12p70 secretion. We examined if specific individual components of the tumour conditioned media (CCL2, CXCL1, CXCL5) could modulate dendritic cell maturation or cytokine secretion in response to LPS. VEGF was also assessed as it has a suppressive effect on dendritic cell maturation. Pre-treatment of immature dendritic cells with VEGF inhibited LPS induced upregulation of CD80 and CD54, while CXCL1 inhibited HLA-DR. Interestingly, treatment of dendritic cells with CCL2, CXCL1, CXCL5 or VEGF significantly suppressed their ability to secrete IL-12p70 in response to LPS. In addition, dendritic cells treated with a combination of CXCL1 and VEGF secreted less IL-12p70 in response to LPS compared to pre-treatment with either cytokine alone. In conclusion, tumour conditioned media strongly influences dendritic cell maturation and function.

Host-derived MCP-1 and MIP-1α regulate protective anti-tumor immunity to localized and metastatic B16 melanoma

Leukocytic infiltration into malignant melanoma lesions is tightly regulated by chemokines. To assess the role of the CC chemokines monocyte chemotactic protein-1 (MCP-1/chemokine ligand 2) and macrophage inflammatory protein-1α (MIP-1α/chemokine ligand 3) in this process, s.c. primary and metastatic B16 F10 melanoma tumor growth levels were examined in mice lacking MCP-1 or MIP-1α. Primary s.c. B16 F10 melanoma growth was augmented by loss of MCP-1 or MIP-1α. Similarly, lung metastasis was enhanced by the deficiency of MCP-1 or MIP-1α. Enhanced tumor outgrowth was associated with decreased percentages of infiltrating CD4(+) T cells, CD8(+) T cells, and natural killer cells. In the absence of MCP-1 or MIP-1α, melanoma outgrowth was correlated with reduced local expression of interferon-γ, IL-6, tumor necrosis factor-α, and transforming growth factor-β. Among these cytokines, reduced expression levels of interferon-γ and tumor necrosis factor-α on leukocytes from the spleen were associated with the development of lung metastasis in chemokine-deficient mice. The local s.c. administration of these four cytokines significantly augmented another chemokine's expression and suppressed primary melanoma growth in mice deficient for MCP-1 or MIP-1α. The s.c. injection of MCP-1 or MIP-1α significantly inhibited the primary tumor growth in wild-type mice. These results indicate that host-derived MCP-1 and MIP-1α regulate protective anti-tumor immunity to B16 F10 melanoma by promoting lymphocyte infiltration into the tumor and subsequent cytokine production.

Intracerebral administration of recombinant rabies virus expressing GM-CSF prevents the development of rabies after infection with street virus

Recently it was found that prior immunization with recombinant rabies virus (RABV) expressing granulocyte-macrophage colony-stimulating factor (GM-CSF) (LBNSE-GM-CSF) resulted in high innate/adaptive immune responses and protection against challenge with virulent RABV (Wen et al., JVI, 2011). In this study, the ability of LBNSE-GM-CSF to prevent animals from developing rabies was investigated in mice after infection with lethal doses of street RABV. It was found that intracerebral administration of LBNSE-GM-CSF protected more mice from developing rabies than sham-treated mice as late as day 5 after infection with street RABV. Intracerebral administration of LBNSE-GM-CSF resulted in significantly higher levels of chemokine/cytokine expression and more infiltration of inflammatory and immune cells into the central nervous system (CNS) than sham-administration or administration with UV-inactivated LBNSE-GM-CSF. Enhancement of blood-brain barrier (BBB) permeability and increases in virus neutralizing antibodies (VNA) were also observed in mice treated with LBNSE-GM-CSF. On the other hand, intracerebral administration with UV-inactivated LBNSE-GM-CSF did not increase protection despite the fact that VNA were induced in the periphery. However, intracerebral administration with chemoattractant protein-1 (MCP-1, also termed CCL2) increased significantly the protective efficacy of UV-inactivated LBNSE-GM-CSF. Together these studies confirm that direct administration of LBNSE-GM-CSF can enhance the innate and adaptive immunity as well as the BBB permeability, thus allowing infiltration of inflammatory cells and other immune effectors enter into the CNS to clear the virus and prevent the development of rabies.

Chemokines and inflammatory mediators interact to regulate adult murine neural precursor cell proliferation, survival and differentiation

Adult neural precursor cells (NPCs) respond to injury or disease of the CNS by migrating to the site of damage or differentiating locally to replace lost cells. Factors that mediate this injury induced NPC response include chemokines and pro-inflammatory cytokines, such as tumor necrosis factor-α (TNFα) and interferon-γ (IFNγ), which we have shown previously promotes neuronal differentiation. RT-PCR was used to compare expression of chemokines and their receptors in normal adult mouse brain and in cultured NPCs in response to IFNγ and TNFα. Basal expression of many chemokines and their receptors was found in adult brain, predominantly in neurogenic regions, with OB≫SVZ>hippocampus and little or no expression in non-neurogenic regions, such as cortex. Treatment of SVZ-derived NPCs with IFNγ and TNFα (alone and in combination) resulted in significant upregulation of expression of specific chemokines, with CXCL1, CXCL9 and CCL2 most highly upregulated and CCL19 downregulated. Unlike IFNγ, chemokine treatment of NPCs in vitro had little or no effect on survival, proliferation or migration. Neuronal differentiation was promoted by CXCL9, CCL2 and CCL21, while astrocyte and total oligodendrocyte differentiation was not affected. However, IFNγ, CXCL1, CXCL9 and CCL2 promoted oligodendrocyte maturation. Therefore, not only do NPCs express chemokine receptors, they also produce several chemokines, particularly in response to inflammatory mediators. This suggests that autocrine or paracrine production of specific chemokines by NPCs in response to inflammatory mediators may regulate differentiation into mature neural cell types and may alter NPC responsiveness to CNS injury or disease.

Upregulation of pancreatic derived factor (FAM3B) expression in pancreatic β-cells by MCP-1 (CCL2)

Pancreatic derived factor (PANDER, FAM3B) is a peptide mainly synthesized and secreted by pancreatic β-cells. PANDER is proposed to be involved in regulation of β-cell function under physiological conditions and impairment of β-cell function under pathological conditions. MCP-1 (CCL2) is expressed by normal pancreatic islets and has been implicated in inflammation related pancreatic disorders. We examined the effect of MCP-1 on PANDER expression by using murine pancreatic β-cell line MIN6 and pancreatic islets. We found that MCP-1 induced PANDER mRNA transcription and protein synthesis in MIN6 cells and islets. By using calcium chelator (EGTA); inhibitors for PKC (Go6976), MEK1/2 (PD98059) or c-Jun-N-terminal kinase (JNK) (SP600125); c-Jun dominant-negative construct; PANDER promoter luciferase constructs; and islets isolated from Fos knockout mice; we demonstrated that MCP-1 induced PANDER gene expression in β-cells through Ca(2+)-ERK1/2-AP-1 and PKC-JNK-AP-1 signaling pathways. Our findings suggest a new link between the endocrine and immune systems and provide useful information for further investigating the physiological functions of PANDER and its involvement in inflammation-related pancreatic disorders.

Peroxisome proliferator-activated receptor-γ agonist rosiglitazone prevents albuminuria but not glomerulosclerosis in experimental diabetes

BACKGROUNDS/AIMS

Renal inflammation and nephrin downregulation contribute to albuminuria in diabetes. We studied, in streptozotocin-induced diabetic rats, the effect of rosiglitazone (RSG), a peroxisome proliferator-activated receptor-γ agonist, on renal macrophage infiltration, MCP1, and nephrin expression in relation to albuminuria.

METHODS

We investigated control and diabetic rats treated or untreated with RSG. Animals were sacrificed at 1, 3, and 9 months. Renal MCP1 and nephrin expression were studied by immunoblotting, renal macrophage infiltration by immunohistochemistry, and albuminuria by ELISA. Electron microscopy was used to assess glomerular ultrastructural morphology. In vitro experiments were conducted in isolated cultured rat glomeruli.

RESULTS

Glycaemic control was similar in diabetic rats treated and untreated with RSG, and blood pressure was comparable in all groups. RSG prevented diabetes-induced albuminuria at 9 months, and renal macrophage infiltration and MCP1 upregulation at 3 and 9 months. Diabetes-mediated nephrin downregulation was abolished by RSG. Diabetes-induced glomerulosclerosis, glomerular basement membrane thickening, and foot process fusion were not affected by RSG. In isolated glomeruli, MCP1 directly induced nephrin downregulation and this was prevented by RSG. RSG had no effect on nephrin expression.

CONCLUSION

RSG prevents albuminuria and nephrin downregulation in experimental diabetes independently of glycaemic and blood pressure control. This effect likely occurs via correction of diabetes-induced inflammatory processes.

[Experimental study on effect of monocyte chemoattractant protein 1 on migration of induced and differentiated mouse bone marrow mesenchymal stem cells in vitro]

OBJECTIVE

To investigate the effect of monocyte chemoattractant protein 1 (MCP-1) on the migration of the induced and differentiated mouse bone marrow mesenchymal stem cells (BMSCs) for raising the efficacy of intravenous transplantation of BMSCs.

METHODS

The BMSCs were cultured with the method of differential adhesion and density gradient centrifugation of C57/BL10 mice, and were identified by alkaline phosphatase Gomori modified staining after osteogenic inducing. At the 3rd passage, the BMSCs were induced to the myoblasts with 5-azacytidine (5-Aza). The chemotaxis of MCP-1 in the induced and differentiated BMSCs in vitro at concentrations of 25, 50, 100, 200, and 400 ng/mL was observed through the migration test, by counting the number of the migrated cells. The expression of the chemokine receptor 2 (CKR-2) in the induced and differentiated BMSCs was detected with the flow cytometry.

RESULTS

The cells could be cultured with the methods of differential adhesion and density gradient centrifugation and still had higher proliferative and differentiative potency; the induced cells at the 3rd passage could differentiate to the osteoblasts, confirming that the cells were BMSCs; the myogenic induced BMSCs possessed the sarcotubule structure. The number of the migrating BMSCs at MCP-1 concentrations of 25-400 ng/mL were respectively 35.066 7 +/- 6.584 2, 43.200 0 +/- 6.460 8, 44.466 7 +/- 4.823 5, 45.600 0 +/- 8.650 3, and 50.733 3 +/- 7.582 5; showing significant difference when compared with control group (28.333 3 +/- 8.917 6, P < 0.05), and presenting significant difference among 25, 50, 400 ng/mL groups compared with each other (P < 0.05). The expression of CKR-2 in the mouse BMSCs (48.0%) was significantly higher (P < 0.001) than those of blank control (0.6%) and negative control (17.0%).

CONCLUSION

The results indicate that the MCP-1 can induce the migration of mouse BMSCs by MCP-1/CKR-2 pathway.

CCL2 is induced by chemotherapy and protects prostate cancer cells from docetaxel-induced cytotoxicity

BACKGROUND

Metastatic prostate cancer is either inherently resistant to chemotherapy or rapidly acquires this phenotype after chemotherapy exposure. In this study, we identified a docetaxel-induced resistance mechanism centered on CCL2.

METHODS

We compared the gene expression profiles in individual human prostate cancer specimens before and after exposure to chemotherapy collected from previously untreated patients who participated in a clinical trial of preoperative chemotherapy. Subsequently, we used the gain- and loss-of-function approach in vitro to identify a potential mechanism underlying chemotherapy resistance.

RESULTS

Among the molecular signatures associated with treatment, several genes that regulate the inflammatory response and chemokine activity were upregulated including a significant increase in transcripts encoding the CC chemokine CCL2. Docetaxel increased CCL2 expression in prostate cancer cell lines in vitro. CCL2-specific siRNA inhibited LNCaP and LAPC4 cell proliferation and enhanced the growth inhibitory effect of low-dose docetaxel. In contrast, overexpression of CCL2 or recombinant CCL2 protein stimulated prostate cancer cell proliferation and rescued cells from docetaxel-induced cytotoxicity. This protective effect of CCL2 was associated with activation of the ERK/MAP kinase and PI3K/AKT, inhibition of docetaxel-induced Bcl2 phosphorylation at serine 70, phosphorylation of Bad, and activation of caspase-3. The addition of a PI3K/AKT inhibitor Ly294002 reversed the CCL2 protection and was additive to docetaxel-induced toxicity.

CONCLUSION

These results support a mechanism of chemotherapy resistance mediated by cellular stress responses involving the induction of CCL2 expression and suggest that inhibiting CCL2 activity could enhance therapeutic responses to taxane-based therapy.

Regulation of adiponectin secretion by adipocytes in the polycystic ovary syndrome: role of tumor necrosis factor-{alpha}

CONTEXT

Adipose tissue dysfunction associated with low-grade chronic inflammation and dysregulation of adipokine secretion might significantly contribute to the pathogenesis of polycystic ovary syndrome (PCOS).

OBJECTIVE

The objective of the study was to determine whether the effect of TNF-alpha, IL-6, monocyte chemoattractant protein-1, or coculture of adipocytes and adipose tissue macrophages (ATMs), on the secretion of adiponectin by adipocytes, differs in PCOS compared with controls.

DESIGN AND PARTICIPANTS

Primary cultures of sc adipocytes and coculture of adipocytes and ATMs from overweight and obese patients with PCOS and healthy control women were used.

MAIN OUTCOME MEASURES

Adiponectin secretion by adipocytes was measured.

RESULTS

The baseline secretion of adiponectin by isolated adipocytes did not differ between PCOS and control samples. The net change in adiponectin secretion in response to IL-6, monocyte chemoattractant protein-1, and TNF-alpha differed between PCOS (decreasing) and control (increasing) adipocytes, although the difference reached significance only for TNF-alpha (P < 0.04). Coculture of isolated adipocytes and ATMs resulted in a decrease in adiponectin secretion by PCOS (P < 0.05) but not control adipocytes, and the difference between the net change in adiponectin secretion in PCOS vs. control samples was significant (P < 0.03).

CONCLUSIONS

Our results suggest that adiponectin secretion by adipocytes in response to cytokines/chemokines and most notably in response to coculturing with ATMs differs between PCOS and control women, favoring greater suppression of adiponectin in PCOS. The mechanisms underlying these defects and the role of concurrent obesity remain to be determined.

OmpA-like protein Loa22 from Leptospira interrogans serovar Lai is cytotoxic to cultured rat renal cells and promotes inflammatory responses

Leptospirosis renal disease is one of the common clinical manifestations of leptospirosis, including acute renal failure and tubulointerstitial nephritis. Outer membrane protein A-like protein Loa22 is a lipoprotein from Leptospira interrogans and has been suggested to be a corresponding virulence factor. However, the role of Loa22 in leptospiral nephropathy is not yet understood. In the present study, we constructed a vector and artificially expressed Loa22 in Escherichia coli BL21(DE)pLysS cells. After extensive purification, along with a GST tag protein control, Loa22 protein was used to test the cytotoxicity in cultured rat proximal tubule cells (NRK52E) and examine its effects on the induction of inflammatory responses. Using morphological examination, 2,3-bis(2-methoxy-4- nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazoium hydrixide absorbance, lactate dehydrogenase assays and an analysis of apoptosis via flow cytometry, it was found that Loa22 protein mediates a direct cytotoxic effect on NRK52E cells in a dose-dependent manner. Using real-time PCR, western blotting and immunofluorescence, it was found that Loa22 protein upregulates the expression of toll-like receptor 2 (TLR2), induces nitric oxide synthase and promotes the production of nitric oxide (NO) and monocyte chemoattractant protein-1 (MCP-1) by NRK52E cells. Additionally, using a TLR2 blocking antibody, it was found that enhanced NO and MCP-1 production by NRK52E cells after Loa22 stimulation requires the activation of TLR2. Collectively, our data suggested that Loa22 is a critical virulence factor of L. interrogans and is involved in the leptospiral nephropathy through mediating direct cytotoxicity and enhancing inflammatory responses.

Effect of the monocyte chemoattractant protein-1/CC chemokine receptor 2 system on nephrin expression in streptozotocin-treated mice and human cultured podocytes

OBJECTIVE

Monocyte chemoattractant protein-1 (MCP-1), a chemokine binding to the CC chemokine receptor 2 (CCR2) and promoting monocyte infiltration, has been implicated in the pathogenesis of diabetic nephropathy. To assess the potential relevance of the MCP-1/CCR2 system in the pathogenesis of diabetic proteinuria, we studied in vitro if MCP-1 binding to the CCR2 receptor modulates nephrin expression in cultured podocytes. Moreover, we investigated in vivo if glomerular CCR2 expression is altered in kidney biopsies from patients with diabetic nephropathy and whether lack of MCP-1 affects proteinuria and expression of nephrin in experimental diabetes.

RESEARCH DESIGN AND METHODS

Expression of nephrin was assessed in human podocytes exposed to rh-MCP-1 by immunofluorescence and real-time PCR. Glomerular CCR2 expression was studied in 10 kidney sections from patients with overt nephropathy and eight control subjects by immunohistochemistry. Both wild-type and MCP-1 knockout mice were made diabetic with streptozotocin. Ten weeks after the onset of diabetes, albuminuria and expression of nephrin, synaptopodin, and zonula occludens-1 were examined by immunofluorescence and immunoblotting.

RESULTS

In human podocytes, MCP-1 binding to the CCR2 receptor induced a significant reduction in nephrin both mRNA and protein expression via a Rho-dependent mechanism. The MCP-1 receptor, CCR2, was overexpressed in the glomerular podocytes of patients with overt nephropathy. In experimental diabetes, MCP-1 was overexpressed within the glomeruli and the absence of MCP-1 reduced both albuminuria and downregulation of nephrin and synaptopodin.

CONCLUSIONS

These findings suggest that the MCP-1/CCR2 system may be relevant in the pathogenesis of proteinuria in diabetes.

Monocytes and neutrophils exhibit both distinct and common mechanisms in penetrating the vascular basement membrane in vivo

OBJECTIVE

Leukocyte migration through venular walls is a fundamental event during inflammation, but many aspects of this response, including the mechanisms associated with leukocyte migration through the vascular basement membrane (BM) in vivo, are poorly understood. Here we investigated and compared the means by which neutrophils and monocytes migrate through the venular BM. Specifically, as we have previously reported on the existence of neutrophil permissive sites (termed matrix protein low expression regions; LERs) within the venular BM, we have now investigated the role of these sites in monocyte transmigration in vivo.

METHODS AND RESULTS

Analysis of CCL2-stimulated mouse cremaster muscles by immunofluorescent staining and confocal microscopy demonstrated that both neutrophils and monocytes use LERs for penetrating venular walls, but independent and distinct mechanisms are used by the 2 cell types. Collectively, (1) neutrophil but not monocyte transmigration led to enlargement of LERs, (2) monocytes showed a greater extent of deformability in migrating through the venular BM, and (3) only extravasated neutrophils were associated with the carriage of laminin fragments.

CONCLUSIONS

The findings provide novel insights into mechanisms of leukocyte transmigration by presenting the first in vivo evidence for distinct modes used by neutrophils and monocytes in penetrating the vascular BM.

Synergy-inducing chemokines enhance CCR2 ligand activities on monocytes

The migration of monocytes to sites of inflammation is largely determined by their response to chemokines. Although the chemokine specificities and expression patterns of chemokine receptors are well defined, it is still a matter of debate how cells integrate the messages provided by different chemokines that are concomitantly produced in physiological or pathological situations in vivo. We present evidence for one regulatory mechanism of human monocyte trafficking. Monocytes can integrate stimuli provided by inflammatory chemokines in the presence of homeostatic chemokines. In particular, migration and cell responses could occur at much lower concentrations of the CCR2 agonists, in the presence of chemokines (CCL19 and CCL21) that per se do not act on monocytes. Binding studies on CCR2(+) cells showed that CCL19 and CCL21 do not compete with the CCR2 agonist CCL2. Furthermore, the presence of CCL19 or CCL21 could influence the degradation of CCL2 and CCL7 on cells expressing the decoy receptor D6. These findings disclose a new scenario to further comprehend the complexity of chemokine-based monocyte trafficking in a vast variety of human inflammatory disorders.

Suppression of the lipopolysaccharide-induced expression of MARCKS-related protein (MRP) affects transmigration in activated RAW264.7 cells

The molecular action mechanism of MRP, one of the protein kinase C (PKC) substrates, has been under intense investigation, but reports on its role in macrophage function remain controversial. The treatment of macrophage cell lines with bacterial lipopolysaccharide (LPS) induced a high level of MRP expression suggesting that MRP plays a role in the function of activated macrophages. In order to investigate the role of MRP in activated RAW264.7 cells, we stably transfected MRP-specific shRNA expression constructs and tested for alterations in macrophage-related functions. The down-regulation of MRP expression resulted in a marked reduction in chemotaxis toward MCP-1 or extracellular matrix proteins. Furthermore, pharmacological inhibitors of PKC significantly inhibited the chemotaxis in RAW264.7 cells. These data reveals the pivotal role of MRP in the transmigration of activated RAW264.7 cells.

Effects of synthetic monocyte chemotactic protein-1 fragment 65-76 on neointima formation after carotid artery balloon injury in rats

The effects of the synthetic monocyte chemotactic protein-1 (MCP-1) peptide fragment 65-76 (peptide X) on the development of neointima after balloon injury to the carotid artery were studied. The agent was given i.m. at a dose of 33 microg/kg once daily for 28 days after balloon injury. Animals given peptide showed significant suppression of neointima growth 4 and 7 days after lesioning, as indicated by morphometric analysis of sections of lesioned arteries. On days 14 and 28, there were no significant differences in neointima formation in rats given and not given peptide. Peptide administration was not accompanied by any changes in C-reactive peptide concentrations, leukocyte counts, or the population composition of peripheral blood lymphocytes. Use of synthetic peptide X as an inhibitor of leukocyte migration during angioplasty may, along with traditional treatments, decrease the risk of restenosis.

An engineered monomer of CCL2 has anti-inflammatory properties emphasizing the importance of oligomerization for chemokine activity in vivo

We demonstrated recently that P8A-CCL2, a monomeric variant of the chemokine CCL2/MCP-1, is unable to induce cellular recruitment in vivo, despite full activity in vitro. Here, we show that this variant is able to inhibit CCL2 and thioglycollate-mediated recruitment of leukocytes into the peritoneal cavity and recruitment of cells into lungs of OVA-sensitized mice. This anti-inflammatory activity translated into a reduction of clinical score in the more complex inflammatory model of murine experimental autoimmune encephalomyelitis. Several hypotheses for the mechanism of action of P8A-CCL2 were tested. Plasma exposure following s.c. injection is similar for P8A-CCL2 and wild-type (WT) CCL2, ruling out the hypothesis that P8A-CCL2 disrupts the chemokine gradient through systemic exposure. P8A-CCL2 and WT induce CCR2 internalization in vitro and in vivo; CCR2 then recycles to the cell surface, but the cells remain refractory to chemotaxis in vitro for several hours. Although the response to P8A-CCL2 is similar to WT, this finding is novel and suggests that despite the presence of the receptor on the cell surface, coupling to the signaling machinery is retarded. In contrast to CCL2, P8A-CCL2 does not oligomerize on glycosaminoglycans (GAGs). However, it retains the ability to bind GAGs and displaces endogenous JE (murine MCP-1) from endothelial surfaces. Intravital microscopy studies indicate that P8A-CCL2 prevents leukocyte adhesion, while CCL2 has no effect, and this phenomenon may be related to the mechanism. These results suggest that oligomerization-deficient chemokines can exhibit anti-inflammatory properties in vivo and may represent new therapeutic modalities.

SPARC ameliorates ovarian cancer-associated inflammation

We have recently identified that the role of secreted protein acidic and rich in cysteine (SPARC) in amelioration of peritoneal ovarian carcinomatosis is mediated, at least in part, through mesothelial cell/lysophosphatidic acid-induced inflammatory response in ovarian cancer cells. The aim of this study was to elucidate the molecular mechanisms of the interactions between tumor cells and the cellular components of the ovarian cancer peritoneal microenvironment, specifically, mesothelial cells and macrophages. We found that SPARC not only significantly reduced macrophage chemoattractant protein-1 production and its macrophage chemotactic effect, but also attenuated the response of ovarian cancer cells to the mitogenic and proinvasive effects of macrophage chemo-attractant protein-1 and decreased macrophage-induced cancer cell invasiveness. Overexpression of SPARC in ovarian cancer cells significantly attenuated macrophage- and mesothelial cell-induced production and activity of interleukin-6, prostanoids (prostaglandins E2 and 8-isoprostanes) as well as matrix metalloproteinases and urokinase plasminogen activator. Moreover, the effects of SPARC overexpression in ovarian cancer cells were mediated, in part, through inhibition of nuclear factor-kappaB promoter activation. These results indicate, for the first time, that the effects of tumor SPARC as a negative regulator of ovarian cancer are mediated through decreased recruitment of macrophages and downregulation of the associated inflammation.

Regulation of mammary parenchymal growth by the fat pad in prepubertal dairy heifers: role of inflammation-related proteins

In prepubertal heifers, the mammary parenchyma consists of epithelial and myoepithelial cells growing within a mammary fat pad (MFP). The MFP produces IGF-I that stimulates epithelial cell proliferation. In other species, adipose tissue expansion induces inflammation-related proteins (IRP), such as tumor necrosis factor alpha (TNFalpha), interleukin (IL)-6, IL-1beta transforming growth factor beta, monocyte chemoattractant protein 1 (MCP-1), and plasminogen activator inhibitor-1 (PAI-1). The MFP production of IRP may influence mammary development because they impair not only insulin but also IGF-I actions. Moreover, the MFP expansion seen with development and increased nutrition coincides with reduced parenchymal growth. Our first objective was to identify IRP capable of altering proliferation of bovine mammary epithelial cells. TNFalpha, but neither IL-6, IL-1beta MCP-1 nor PAI-1, inhibited basal and IGF-I-stimulated proliferation in MAC-T cells and primary cells isolated from heifers. Our second objective was to determine whether MFP expression of IRP changed in a manner consistent with inhibition of parenchymal growth. MFP expression was measured from 100 to 350 kg body weight (experiment 1) or at 240 kg body weight (experiment 2) in dairy heifers offered restricted or high planes of nutrition. In experiment 1, neither nutrition nor development altered MFP expression of TNFalpha. Nutrition increased MCP-1 and PAI-1 but only before MFP expansion and after cessation of allometric parenchymal growth. In experiment 2, nutrition increased TNFalpha and PAI-1, but not MCP-1. Thus, MFP expansion increases IRP production in cattle, but this is unlikely to contribute to reduced parenchymal growth observed with development or increased nutrition.

[Effects of induction of tubular epithelial-myofibroblast transition by monocyte chemoattractant protein-1 and mechanism thereof: an in vitro experiment]

OBJECTIVE

To examine the effects of monocyte chemoattractant protein-1 (MCP-1) on epithelial-myofibroblast transition (EMT) of renal proximal tubular epithelial cells and the possible mechanism involved.

METHODS

Human renal proximal tubular epithelial cells of the line HK-2 were cultured and divided into three groups: negative control group; positive control group, treated with transforming growth factor (TGF)-beta1 5 microg/L, and MPC-1 group, treated with MCP-1 0.1, 1, 10, and 100 microg/L for 24 h, 36 h, 48 h, and 72 h respectively. The expressions of alpha-smooth muscle actin (alpha-SMA) mRNA and protein of cells were detected by s. Western blotting and RT-PCR were used to detect the expression of P-Erk1/2, Erk1/2, P-P38MAPK, P38MAPK, and RhoA protein levels of the HK-2 cells, and RT-PCR was used to detect the expression of RhoC and Snail mRNA. Specific inhibitors of the Erk, P38MAPK, and Rho signal transduction pathways PD98059, SB203580, and Y27632 were added into the culture fluid of HK-2 cells respectively, 1 h later MCP-1 microg/L was added for 48 h, and Western blotting was used to detect the protein expression of alpha-small muscle actin (SMA).

RESULTS

The expression levels of alpha-SMA protein and mRNA significantly increased in the MCP-1 treated HK-2 cells,and these expression levels were the highest in the HK-2 cells treated with MCP-1 1 microg/L for 48 h. The ratios of (P-Erk1/2)/ (Erk1/2) and P-P38MAPK/P38MAPK were significantly increased (all P < 0.05) in the MCP-1 treated HK-2 cells with the highest ratios seen in the HK-2 cells treated by 100 microg/L of MCP-1. The expression levels of RhoA protein and RhoC mRNA of the HK-2 cells stimulated with MCP-1 of different concentrations were not significantly different (all P > 0.05). MCP-1 induced expression of a-SMA was only partly inhibited by PD98059 but not by SB203587 or Y27632. MCP-1 dose-dependently increased the expression of Snail mRNA of the HK-2 cells compared with those of the negative control cells. The level of Snail mRNA was the highest in the HK-2 cells treated with 100 microg/L MCP-1.

CONCLUSION

MCP-1 may induce the EMT of renal proximal tubular epithelial cells in vitro, and this effect may involve upregulation of Erk1/2 Map kinase signal pathways and Snail mRNA expression. P38MAPK or Rho kinase signal pathways can not be proven to be involved in MCP-1 induced EMT.

Role of astrocytes and chemokine systems in acute TNFalpha induced demyelinating syndrome: CCR2-dependent signals promote astrocyte activation and survival via NF-kappaB and Akt

Chemotactic factors known as chemokines play an important role in the pathogenesis of multiple sclerosis (MS). Transgenic expression of TNFalpha in the central nervous system (CNS) leads to the development of a demyelinating phenotype (TNFalpha-induced demyelination; TID) that is highly reminiscent of MS. Little is known about the role of chemokines in TID but insights derived from studying this model might extend our current understanding of MS pathogenesis and complement data derived from the classic autoimmune encephalomyelitis (EAE) model system. Here we show that in TID, chemokines and their receptors were significantly increased during the acute phases of disease. Notably, the CCL2 (MCP-1)-CCR2 axis and the closely related ligand-receptor pair CCR1-CCL3 (MIP-1alpha) were among the most up-regulated during disease. On the other hand, receptors like CCR3 and CCR4 were not elevated. This significant increase in the levels of chemokines/receptors correlated with robust immune infiltration of the CNS by inflammatory cells, i.e., macrophages, and immune cells particularly T and B cells. Immunostaining and confocal microscopy, along with in vitro studies revealed that astrocytes were a major source of locally produced chemokines and expressed functional chemokine receptors such as CCR2. Using an in vitro system we demonstrate that expression of CCR2 was functional in astrocytes and that signaling via this receptor lead to activation of NF-kB and Akt and was associated with increased astrocyte survival. Collectively, our data suggests that transgenic murine models of MS are useful to dissect mechanisms of disease and that in these models, up-regulation of chemokines and their receptors may be key determinants in TID.

[The effect of synthetic fragment 65-76 of monocyte chemiattractant protein-1 (MCP-1) on neointima growth after carotid artery balloon injury in rats]

Influence of synthetic fragment 65-76 of monocyte chemoattractant protein-1 (MCP-1) (peptide X) on development of neointima after balloon injury of carotid artery was investigated. Peptide X was introduced intramuscularly, 33 pg/kg, daily during 28 days after balloon injury. In days 4 and 7 after intervention, in animals receiving peptide X in comparison with control animals a substantial decrease of neointimal growth was observed. On 14 and 28 days there, was no significant difference in neointima development in rats with and without peptide treatment. Injections of peptide X did not after the C-reactive protein concentration, leukocyte number and lymphocyte subpopulations in peripheral blood. Peptide X treatment along with traditional therapy may be effective in preventing restenosis after angioplasty.