Increased proatherogenic monocyte-platelet cross-talk in monocyte subpopulations of patients with stable coronary artery disease

BACKGROUND

Monocytes and platelets are important cellular mediators of atherosclerosis. Human monocytes can be divided into CD14(++) CD16(-) , CD14(++) CD16(+) and CD14(+) CD16(++) cells, which differ in their functional properties. The aim of this study was to examine monocyte subset distribution, monocyte-platelet aggregate (MPA) formation and expression of CCR5, the receptor of the platelet-derived chemokine CCL5, and to determine whether these parameters are altered in individuals with coronary atherosclerosis.

METHODS

Peripheral blood cells from 64 healthy blood donors (HBDs) and 60 patients with stable coronary artery disease (CAD) were stained with antibodies against CD14, CD16, CD42b and CCR5 and analysed by flow cytometry. Circulating CCL5 levels were determined using an enzyme-linked immunosorbent assay.

RESULTS

In patients with CAD, the relative proportion of the CD14(++) CD16(-) monocyte subset was elevated (P < 0.05) and of the CD14(+) CD16(++) subset was reduced (P < 0.001) compared with the HBD group. Furthermore, MPA formation significantly increased in patients with CAD in all three monocyte subsets. In both study groups, the majority of CCR5(+) cells was detected in CD14(++) CD16(+) monocytes (P < 0.001 versus CD14(++) CD16(-) and CD14(+) CD16(++) ), although the CCR5(+) monocyte number was reduced in patients with CAD (CD14(++) CD16(-) /CD14(+) CD16(++) , P < 0.001; CD14(++) CD16(+) , P < 0.05) compared with the HBD group, particularly in those who were not taking statins. Ex vivo incubation of monocytes from HBDs with plasma from patients with CAD also decreased CCR5(+) expression (P < 0.05 versus plasma from HBDs). Serum CCL5 levels were similar in both groups.

CONCLUSIONS

The increased monocyte-platelet cross-talk in patients with CAD might have contributed to atherosclerosis progression. The decreased CCR5(+) monocyte numbers in patients with CAD could have resulted from CCR5(+) cell recruitment into atherosclerotic lesions or CCR5 downregulation in response to circulating factors.

The chemokine CCL5 induces CCR1-mediated hyperalgesia in mice inoculated with NCTC 2472 tumoral cells

Although the expression of the chemokine receptor CCR1 has been demonstrated in several structures related to nociception, supporting the nociceptive role of chemokines able to activate it, the involvement of CCR1 in neoplastic pain has not been previously assessed. We have assayed the effects of a CCR1 antagonist, J113863, in two murine models of neoplastic hyperalgesia based on the intratibial injection of either NCTC 2472 fibrosarcoma cells, able to induce osteolytic bone injury, or B16-F10 melanoma cells, associated to mixed osteolytic/osteoblastic bone pathological features. The systemic administration of J113863 inhibited thermal and mechanical hyperalgesia but not mechanical allodynia in mice inoculated with NCTC 2472 cells. Moreover, in these mice, thermal hyperalgesia was counteracted following the peritumoral (10-30μg) but not spinal (3-5μg) administration of J113863. In contrast, hyperalgesia and allodynia measured in mice inoculated with B16-F10 cells remained unaffected after the administration of J113863. The inoculation of tumoral cells did not modify the levels of CCL3 at tumor or spinal cord. In contrast, although the concentration of CCL5 remained unmodified in mice inoculated with B16-F10 cells, increased levels of this chemokine were measured in tumor-bearing limbs, but not the spinal cord, of mice inoculated with NCTC 2472 cells. Increased levels of CCL5 were also found following the incubation of NCTC 2472, but not B16-F10, cells in the corresponding culture medium. The intraplantar injection of CCL5 (0.5ng) to naïve mice evoked thermal hyperalgesia prevented by the coadministration of J113863 or the CCR5 antagonist, d-Ala-peptide T-amide (DAPTA), demonstrating that CCL5 can induce thermal hyperalgesia in mice through the activation of CCR1 or CCR5. However, contrasting with the inhibitory effect evoked by J113863, the systemic administration of DAPTA did not prevent tumoral hyperalgesia. Finally, the peritumoral administration of an anti-CCL5 antibody completely inhibited thermal hyperalgesia evoked by the inoculation of NCTC 2472 cells.

CCL5 and cytokine expression in the rat brain: differential modulation by chronic morphine and morphine withdrawal

Opioids have been shown to influence the immune system and to promote the expression of pro-inflammatory cytokines in the central nervous system. However, recent data have shown that activation of opioid receptors increases the expression and release of the neuroprotective chemokine CCL5 from astrocytes in vitro. To further define the interaction between CCL5 and inflammation in response to opioids, we have examined the effect of chronic morphine and morphine withdrawal on the in vivo expression of CCL5 as well as of pro-inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Rats undergoing a chronic morphine paradigm (10 mg/kg increasing to 30 mg/kg, twice a day for 5 days) showed a twofold increase of CCL5 protein and mRNA within the cortex and striatum. No changes were observed in the levels of IL-1β and TNF-α. Naltrexone blocked the effect of morphine. A chronic morphine paradigm with no escalating doses (10 mg/kg, twice a day) did not alter CCL5 levels compared to saline-treated animals. On the contrary, rats undergoing spontaneous morphine withdrawal exhibited lower levels of CCL5 within the cortex as well as increased levels of pro-inflammatory cytokines and Iba-1 positive cells than saline-treated rats. Overall, these data suggest that morphine withdrawal may promote cytokines and other inflammatory responses that have the potential of exacerbating neuronal damage.

TLR4, rather than TLR2, regulates wound healing through TGF-β and CCL5 expression

BACKGROUND

Toll-like receptors (TLRs) have a crucial role in early host defense against invading pathogens. Recent studies suggest that TLRs play important roles in non-infections inflammation and tissue repair and regeneration.

OBJECTIVE

To determine the roles of TLR2 and TLR4 in mouse wound healing using TLR2-deficient (TLR2(-/-)), TLR4-deficient (TLR4(-/-)), and TLR2/TLR4-deficient (TLR2/4(-/-)) mice.

METHODS

Open wounds made in TLR2(-/-), TLR4(-/-), and TLR2/4(-/-) mice were examined clinically and histologically. Cytokine expression in the wounded skin was also investigated. TGF-β production from macrophages stimulated by hyaluronan, a ligand for TLR2 and TLR4, was evaluated by real-time PCR.

RESULTS

Wound areas in TLR2(-/-), TLR4(-/-), and TLR2/4(-/-) mice were larger than wild-type mice both at days 3 and 7 after wounding, accompanied by decreased numbers of infiltrating macrophages in the dermis and decreased TGF-β and CCL5 mRNA expression in the wounded skin. Immunohistochemistry showed decreased numbers of macrophages expressing TGF-β and reduced CCL5 expression by keratinocytes in the wounded skin from TLR2(-/-), TLR4(-/-), and TLR2/4(-/-) mice compared to wild-type mice. Moreover, TGF-β production from macrophages induced by hyaluronan stimulation in vitro was significantly decreased in the absence of TLRs, especially TLR4. Interestingly, macrophages and wounded skin from TLR2(-/-) mice showed decreased TLR4 mRNA expression compared to wild-type mice, suggesting that the effect of TLR2 deficiency was at least partially dependent on decrease in TLR4. Topical application of TGF-β and CCL5 significantly improved wound healing in TLR-deficient mice.

CONCLUSION

TLR4, rather than TLR2, regulates wound healing through TGF-β and CCL5 expression.

Impaired bone formation and increased osteoclastogenesis in mice lacking chemokine (C-C motif) ligand 5 (Ccl5)

Chemokines play crucial roles in the recruitment of specific hematopoietic cell types, and some of them have been suggested to be involved in the regulation of bone remodeling. Because we have previously observed that chemokine (C-C motif) ligand 2 (Ccl2) and Ccl5 are direct target genes of noncanonical Wnt signaling in osteoblasts, we analyzed the skeletal phenotypes of Ccl2-deficient and Ccl5-deficient mice. In line with previous studies, Ccl2-deficient mice display a moderate reduction of osteoclastogenesis at the age of 6 months. In contrast, 6-month-old Ccl5-deficient mice display osteopenia associated with decreased bone formation and increased osteoclastogenesis. Moreover, unlike in wild-type and Ccl2-deficient mice, large areas of their trabecular and endocortical bone surfaces are not covered by osteoblasts or bone-lining cells, and this is associated with a severe reduction of endosteal bone formation. Although this phenotype diminishes with age, it is important that we could further identify a reduced number of osteal macrophages in 6-month-old Ccl5-deficient mice, because this cell type has previously been reported to promote endosteal bone formation. Because Ccl5-deficient mice also display increased osteoclastogenesis, we finally addressed the question of whether osteal macrophages could differentiate into osteoclasts and/or secrete inhibitors of osteoclastogenesis. For that purpose we isolated these cells by CD11b affinity purification from calvarial cultures and characterized them ex vivo. Here we found that they are unable to differentiate into osteoblasts or osteoclasts, but that their conditioned medium mediates an antiosteoclastogenic effect, possibly caused by interleukin-18 (IL-18), an inhibitor of osteoclastogenesis expressed by osteal macrophages. Taken together, our data provide in vivo evidence supporting the previously suggested role of Ccl5 in bone remodeling. Moreover, to the best of our knowledge, Ccl5-deficient mice represent the first model with a spontaneous partial deficiency of osteal macrophages, a recently identified cell type, whose impact on bone remodeling is just beginning to be understood.

Low-molecular-mass secretome profiling identifies C-C motif chemokine 5 as a potential plasma biomarker and therapeutic target for nasopharyngeal carcinoma

Cancer cell secretome profiling has been shown to be a promising strategy for identifying potential body fluid-accessible cancer biomarkers and therapeutic targets. However, very few reports have investigated low-molecular-mass (LMr) proteins (<15kDa) in the cancer cell secretome. In the present study, we applied tricine-SDS-gel-assisted fractionation in conjunction with LC-MS/MS to systemically identify LMr proteins in the secretomes of three nasopharyngeal carcinoma (NPC) cell lines. We examined two NPC tissue transcriptome datasets to identify LMr genes/proteins that are highly upregulated in NPC tissues and also secreted/released from NPC cells, obtaining 35 candidates. We verified the overexpression of four targets (LSM2, SUMO1, RPL22, and CCL5) in NPC tissues by immunohistochemistry and demonstrated elevated plasma levels of two targets (S100A2 and CCL5) in NPC patients by ELISA. Notably, plasma CCL5 showed good power (AUC 0.801) for discriminating NPC patients from healthy controls. Additionally, functional assays revealed that CCL5 promoted migration of NPC cells, an effect that was effectively blocked by CCL5-neutralizing antibodies and maraviroc, a CCL5 receptor antagonist. Collectively, our data indicate the feasibility of the tricine-SDS-gel/LC-MS/MS approach for efficient identification of LMr proteins from cancer cell secretomes, and suggest that CCL5 is a potential plasma biomarker and therapeutic target for NPC.

BIOLOGICAL SIGNIFICANCE

Both LMr proteome and cancer cell secretome represent attractive reservoirs for discovery of cancer biomarkers and therapeutic targets. Our present study provides evidence for the practicality of using the tricine-SDS-PAGE/LC-MS/MS approach for in-depth identification of LMr proteins from the NPC cell secretomes, leading to the discovery of CCL5 as a potential plasma biomarker and therapeutic target for NPC. We believe that the modified GeLC-MS/MS approach used here can be further applied to explore extremely low-abundance, extracellular LMr proteins with important biological functions in other cell lines and biospecimens.

CCL5-glutamate interaction in central nervous system: Early and acute presynaptic defects in EAE mice

We investigated the CCL5-glutamate interaction in the cortex and in the spinal cord from mice with Experimental Autoimmune Encephalomyelitis (EAE) at 13 and 21/30 days post immunization (d.p.i.), representing the onset and the peak of the disease, respectively. An early reduction of the KCl-evoked glutamate release was observed in cortical terminals from EAE mice at 13 d.p.i., persisting until 21/30 d.p.i. A concomitant reduction of the depolarization-evoked cyclic adenosine monophosphate (cAMP), but not of the inositol 1,4,5-trisphosphate (IP3) cortical production also occurred at 13 d.p.i, that still was detectable at the acute stage of disease (21 dp.i.). Inasmuch, the CCL5-mediated inhibition of glutamate exocytosis observed in control mice turned to facilitation in EAE mouse cortex at 13 d.p.i., then becoming undetectable at 21/30 d.p.i. Differently, glutamate exocytosis, as well as IP3 and cAMP productions were unaltered in spinal cord synaptosomes from EAE mice at 13 d.p.i., but significantly increased at 21/30 d.p.i., while the presynaptic CCL5-mediated facilitation of glutamate exocytosis observed in control mice remained unchanged. In both CNS regions, the presynaptic defects were parallelled by increased CCL5 availability. Inasmuch, the presynaptic defects so far described in EAE mice were reminiscent of the effects acute CCL5 exerts in control conditions. Based on these observations we propose that increased CCL5 bioavailability could have a role in determining the abovedescribed impaired presynaptic impairments in both CNS regions. These presynaptic defects could be relevant to the onset of early cognitive impairments and acute neuroinflammation and demyelinating processes observed in multiple sclerosis patients.

CCR1/CCL5 interaction promotes invasion of taxane-resistant PC3 prostate cancer cells by increasing secretion of MMPs 2/9 and by activating ERK and Rac signaling

Castration-refractory prostate cancer (CRPC) is treated with taxane-based chemotherapy, but eventually becomes drug resistant. It is thus essential to identify novel therapeutic targets for taxane resistance in CRPC patients. We investigated the role of the chemokine (C-C motif) receptor 1 (CCR1) and its ligand, chemokine (C-C motif) ligand 5 (CCL5), in taxane-resistant CRPC using paclitaxel-resistant prostate cancer cells (PC3PR) established from PC3 cells. We found that the expression levels of CCR1 mRNA and protein were up-regulated in PC3PR cells compared to PC3 cells. In order to investigate the role of increased CCR1 in PC3PR cells, we stimulated cells with CCL5, one of the chemokine ligands of CCR1. In CCL5-stimulated PC3PR cells, siRNA-mediated knockdown of CCR1 expression reduced phosphorylation of ERK1/2 and Rac1/cdc42. Furthermore, CCR1 knockdown and MEK1/2 inhibition decreased CCL5-stimulated secretion of MMPs 2 and 9, which play important roles in cancer cell invasion and metastasis. In the Matrigel invasion assay, knockdown of CCR1 and inhibition of the ERK and Rac signaling pathways significantly decreased the number of invading cells. Finally, the serum CCL5 protein level as measured by ELISA was not different among the three groups of patients: those with negative prostate biopsy, those at initial diagnosis of prostate cancer, and those with taxane-resistant prostate cancer. These results demonstrated for the first time that the interaction of CCR1 with CCL5 caused by increased expression of CCR1 promotes invasion of PC3PR cells by increasing secretion of MMPs 2 and 9 and by activating ERK and Rac signaling. Our findings suggest that CCR1 could be a novel therapeutic target for taxane-resistant CRPC.

No association between genetic variants in angiogenesis and inflammation pathway genes and breast cancer survival among Chinese women

BACKGROUND

Angiogenesis and inflammation are implicated in breast cancer prognosis; however, the role of individual germline variation in related genes is unknown.

METHODS

A two-stage candidate pathway association study was conducted among 6983 Chinese women. Stage 1 included 2884 women followed for a median of 5.7 years; Stage 2 included 4099 women followed for a median of 4.0 years. Cox proportional hazards regression was used to estimate the effects of genetic variants on disease-free survival (DFS) and overall survival (OS).

RESULTS

Stage 1 included genotyping of 506 variants in 22 genes; analysis was conducted for 370 common variants. Nominally significant associations with DFS and/or OS were found for 20 loci in ten genes in Stage 1; variants in 19 loci were successfully genotyped and evaluated in Stage 2. In analyses of both study stages combined, nominally significant associations were found for nine variants in seven genes; none of these associations surpassed a significance threshold level corrected for the total number of variants evaluated in this study.

CONCLUSIONS

No association with survival was found for 370 common variants in 22 angiogenesis and inflammation pathway genes among Chinese women with breast cancer.

IMPACT

Our data do not support a large role for common genetic variation in 22 genes in breast cancer prognosis; research on angiogenesis and inflammation genes should focus on common variation in other genes, rare host variants, or tumor alterations.

Cellular and molecular players in adipose tissue inflammation in the development of obesity-induced insulin resistance

There is increasing evidence showing that inflammation is an important pathogenic mediator of the development of obesity-induced insulin resistance. It is now generally accepted that tissue-resident immune cells play a major role in the regulation of this obesity-induced inflammation. The roles that adipose tissue (AT)-resident immune cells play have been particularly extensively studied. AT contains most types of immune cells and obesity increases their numbers and activation levels, particularly in AT macrophages (ATMs). Other pro-inflammatory cells found in AT include neutrophils, Th1 CD4 T cells, CD8 T cells, B cells, DCs, and mast cells. However, AT also contains anti-inflammatory cells that counter the pro-inflammatory immune cells that are responsible for the obesity-induced inflammation in this tissue. These anti-inflammatory cells include regulatory CD4 T cells (Tregs), Th2 CD4 T cells, and eosinophils. Hence, AT inflammation is shaped by the regulation of pro- and anti-inflammatory immune cell homeostasis, and obesity skews this balance towards a more pro-inflammatory status. Recent genetic studies revealed several molecules that participate in the development of obesity-induced inflammation and insulin resistance. In this review, the cellular and molecular players that participate in the regulation of obesity-induced inflammation and insulin resistance are discussed, with particular attention being placed on the roles of the cellular players in these pathogeneses. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.

RANTES and fibroblast growth factor 2 in jawbone cavitations: triggers for systemic disease?

Background

Jawbone cavitations (JC) are hollow dead spaces in jawbones with dying or dead bone marrow. These areas are defined as fatty degenerative osteonecrosis of the jawbone or neuralgia-inducing cavitational osteonecrosis and may produce facial pain. These afflictions have been linked to the immune system and chronic illnesses. Surgical debridement of JC is reported to lead to an improvement in immunological complaints, such as rheumatic, allergic, and other inflammatory diseases (ID). Little is known about the underlying cause/effect relationship.

Objectives

JC bone samples were analyzed to assess the expression and quantification of immune modulators that can play a role in the pathogenesis of IDs. The study supports a potential mechanism where JC is a mediating link in IDs.

Materials and methods

Samples of fatty softened bone taken from JCs were extracted from 31 patients. The specimens were analyzed by bead-based multiplex technology and tested for seven immune messengers.

Results

Regulated upon activation, normal T-cell expressed, and secreted (RANTES) and fibroblast growth factor (FGF)-2 were found at high levels in the JCs tested. Other cytokines could not be detected at excessive levels.

Discussion

The study confirms that JC is able to produce inflammatory messengers, primarily RANTES, and, secondarily, FGF-2. Both are implicated in many serious illnesses. The excessive levels of RANTES/FGF-2 in JC patients with amyotrophic lateral sclerosis, multiple sclerosis, rheumatoid arthritis, and breast cancer are compared to levels published in medical journals. Levels detected in JCs are higher than in the serum and cerebrospinal fluid of amyotrophic lateral sclerosis and multiple sclerosis patients and four-fold higher than in breast cancer tissue.

Conclusion

This study suggests that JC might serve as a fundamental cause of IDs, through RANTES/FGF-2 production. Thus, JC and implicated immune messengers represent an integrative aspect of IDs and serve as a possible cause. Removing JCs may be a key to reversing IDs. There is a need to raise awareness about JC throughout medicine and dentistry.

Activation of the small G-protein Rac by human rhinovirus attenuates the TLR3/IFN-α axis while promoting CCL2 release in human monocyte-lineage cells

Although rhinoviral infections, a major cause of asthma exacerbations, occur predominantly in upper airway bronchial epithelial cells, monocytic-lineage cells are implicated in establishing the inflammatory microenvironment observed during the disease. Human rhinovirus (HRV) is unique in that nearly genetically identical viruses bind either the ICAM-1 or low-density lipoprotein receptor (LDL-R). Within minutes of binding, HRV is capable of eliciting a signaling response in both epithelial cells and monocyte-derived macrophages. It is unclear whether this signaling response is important to the subsequent release of inflammatory mediators, particularly in cells not capable of supporting viral replication. We show here that the small molecular mass G-protein Rac is activated following exposure of macrophages to HRV serotypes known to be ICAM-1- and LDL-R-tropic. We demonstrate that inhibiting Rac resulted in the upregulation of TLR3 in macrophages exposed to major- and minor-group HRV, and resulted in increased release of IFN-α. Furthermore, inhibiting Rac in HRV-exposed macrophages attenuated activation of the stress kinase p38 and release of the pro-inflammatory cytokine CCL2, but inhibiting Rac did not affect release of the pro-inflammatory cytokine CCL5. These findings suggest that Rac is an important regulator in establishing the inflammatory microenvironment that is initiated in the human airway upon exposure to rhinovirus.