Chemokine-cytokine cross-talk. The ELR+ CXC chemokine LIX (CXCL5) amplifies a proinflammatory cytokine response via a phosphatidylinositol 3-kinase-NF-kappa B pathway

Interferon-signaling pathways are upregulated in people with HIV with abnormal pulmonary diffusing capacity (DL CO )

OBJECTIVE

People with HIV (PWH) are at greater risk of developing lung diseases even when they are antiretroviral therapy (ART)-adherent and virally suppressed. The most common pulmonary function abnormality in PWH is that of impaired diffusing capacity of the lungs for carbon monoxide (DL CO ), which is an independent risk factor for increased mortality in PWH. Earlier work has identified several plasma biomarkers of inflammation and immune activation to be associated with decreased DL CO . However, the underpinning molecular mechanisms of HIV-associated impaired DL CO are largely unknown.

DESIGN

Cross-sectional pilot study with PWH with normal DL CO (values greater than or equal to the lower limit of normal, DL CO  ≥ LLN, N = 9) or abnormal DL CO (DL CO  < LLN, N = 9).

METHODS

We compared the gene expression levels of over 900 inflammation and immune exhaustion genes in PBMCs from PWH with normal vs. abnormal DL CO using the NanoString technology.

RESULTS

We found that 26 genes were differentially expressed in the impaired DL CO group. These genes belong to 4 categories: 1. Nine genes in inflammation and immune activation pathways, 2. seven upregulated genes that are direct targets of the interferon signaling pathway, 3. seven B-cell specific genes that are downregulated, and 4. three miscellaneous genes. These results were corroborated using the bioinformatics tools DAVID (Database for Annotation, Visualization and Integrated Discovery) and GSEA (Gene Sets Enrichment Analysis).

CONCLUSION

The data provides preliminary evidence for the involvement of sustained interferon signaling as a molecular mechanism for impaired DL CO in PWH.

CXCL5 suppression recovers neovascularization and accelerates wound healing in diabetes mellitus

BACKGROUND

Higher chemokine C-X-C motif ligand 5 (CXCL5) level was observed in type 2 diabetes mellitus (DM) patients; however, its role in diabetic vasculopathy was not clarified. This study aimed to explore the impacts and mechanistic insights of CXCL5 in neovasculogenesis and wound healing in DM.

METHODS

Endothelial progenitor cells (EPCs) and human aortic endothelial cells (HAECs) were used in vitro. Streptozotocin-induced diabetic mice and Leprdb/JNarl mice were used as type 1 and type 2 DM models. Moreover, CXCL5 knockout mice were used to generate diabetic mice. Hindlimb ischemia surgery, aortic ring assays, matrigel plug assay, and wound healing assay were conducted.

RESULTS

CXCL5 concentrations were increased in plasma and EPCs culture medium from type 2 DM patients. CXCL5 neutralizing antibody upregulated vascular endothelial growth factor (VEGF)/stromal cell-derived factor-1 (SDF-1) and promoted cell function in EPCs from type 2 DM patients and high glucose-treated EPCs from non-DM subjects as well as HAECs. CXCL5 directly up-regulated interleukin (IL)-1β/IL-6/tumor necrosis factor-α and down-regulated VEGF/SDF-1 via ERK/p65 activation through chemokine C-X-C motif receptor 2 (CXCR2). CXCL5 neutralizing antibody recovered the blood flow after hindlimb ischemia, increased circulating EPC number, and enhanced VEGF and SDF-1 expression in ischemic muscle. CXCL5 suppression promoted neovascularization and wound healing in different diabetic animal models. The above observation could also be seen in streptozotocin-induced CXCL5 knockout diabetic mice.

CONCLUSIONS

CXCL5 suppression could improve neovascularization and wound healing through CXCR2 in DM. CXCL5 may be regarded as a potential therapeutic target for vascular complications of DM.

Blocking Autophagy in M1 Macrophages Enhances Virus Replication and Eye Disease in Ocularly Infected Transgenic Mice

Autophagy plays a critical role in clearing, disassembling, and recycling damaged cells, thus limiting inflammation. The HSV-1 γ34.5 gene is involved in neurovirulence and immune evasion by blocking autophagy in infected cells.

Utilizing mast cells in a positive manner to overcome inflammatory and allergic diseases

Mast cells (MCs) are immune cells widely distributed in the body, accompanied by diverse phenotypes and functions. Committed mast cell precursors (MCPs) leave the bone marrow and enter the blood circulation, homing to peripheral sites under the control of various molecules from different microenvironments, where they eventually differentiate and mature. Partly attributable to the unique maturation mechanism, MCs display high functional heterogeneity and potentially plastic phenotypes. High plasticity also means that MCs can exhibit different subtypes to cope with different microenvironments, which we call “the peripheral immune education system”. Under the peripheral immune education system, MCs showed a new character from previous cognition in some cases, namely regulation of allergy and inflammation. In this review, we focus on the mucosal tissues, such as the gastrointestinal tract, to gain insights into the mechanism underlying the migration of MCs to the gut or other organs and their heterogeneity, which is driven by different microenvironments. In particular, the immunosuppressive properties of MCs let us consider that positively utilizing MCs may be a new way to overcome inflammatory and allergic disorders.

Endometriosis pain and epithelial neutrophil activating peptide-78 levels

Endometriosis is a chronic gynecological disorder involved in the pathogenesis of chronic pelvic pain, based on a probable up regulation of the inflammatory system. The objective of the study is to investigate the peritoneal and serum levels of ENA-78 with the severity of endometriosis symptoms (dysmenorrhea, chronic pelvic pain and dyspareunia) using the visual analogue scale (VAS). This is a prospective case–control study that included 53 symptomatic women with evidence of endometriosis and 53 age-matched controls who underwent elective laparoscopic surgery for benign diseases. The concentration of ENA-78 was assessed in blood and peritoneal fluid samples in the follicular phase. In peritoneal fluid and plasma, the concentration of ENA-78 was significantly higher in cases than in controls (p < 0.001). A significant correlation was observed between peritoneal fluid ENA-78 levels and the severity of dysmenorrhea (Spearman Rho = 0.237; p = 0.014), and chronic pelvic pain (Spearman Rho = 0.220; p = 0.022) in endometriosis patients. Plasma levels ENA-78 showed a significant correlation with the severity (VAS score) of chronic pelvic pain (Spearman Rho = 0.270, p = 0.005 for cases), though a weak correlation was evident between plasma levels of ENA-78 and severity of dysmenorrhea (Spearman Rho = 0.083, p = 0.399 for cases). In conclusion, chronic pelvic pain in endometriosis is caused by changes of local and systemic activated chemokine patterns. These modifications involve the relationship between pro-inflammatory, angiogenic and angiostatic chemokines that modulate the severity of endometriosis associated symptoms.

An inducible rodent glaucoma model that exhibits gradual sustained increase in intraocular pressure with distinct inner retina and optic nerve inflammation

Glaucoma is a chronic and progressive neurodegenerative disease of the optic nerve resulting in loss of retinal ganglion cells (RGCs) and vision. The most prominent glaucoma risk factor is increased intraocular pressure (IOP), and most models focus on reproducing this aspect to study disease mechanisms and targets. Yet, current models result in IOP profiles that often do not resemble clinical glaucoma. Here we introduce a new model that results in a gradual and sustained IOP increase over time. This approach modifies a circumlimbal suture method, taking care to make the sutures 'snug' instead of tight, without inducing an initial IOP spike. This approach did not immediately affect IOPs, but generated gradual ocular hypertension (gOHT) as the sutures tighten over time, in comparison to loosely sutured control eyes (CON), resulting in an average 12.6 mmHg increase in IOP at 17 weeks (p < 0.001). Corresponding characterization revealed relevant retinal and optic nerve pathology, such as thinning of the retinal nerve fiber layer, decreased optokinetic response, RGC loss, and optic nerve head remodeling. Yet, angles remained open, with no evidence of inflammation. Corresponding biochemical profiling indicated significant increases in TGF-β2 and 3, and IL-1 family cytokines in gOHT optic nerve tissues compared to CON, with accompanying microglial reactivity, consistent with active tissue injury and repair mechanisms. Remarkably, this signature was absent from optic nerves following acute ocular hypertension (aOHT) associated with intentionally tightened sutures, although the resulting RGC loss was similar in both methods. These results suggest that the pattern of IOP change has an important impact on underlying pathophysiology.

Neuroinflammation and Alzheimer's Disease: A Machine Learning Approach to CSF Proteomics

In Alzheimer’s disease (AD), the contribution of pathophysiological mechanisms other than amyloidosis and tauopathy is now widely recognized, although not clearly quantifiable by means of fluid biomarkers. We aimed to identify quantifiable protein biomarkers reflecting neuroinflammation in AD using multiplex proximity extension assay (PEA) testing. Cerebrospinal fluid (CSF) samples from patients with mild cognitive impairment due to AD (AD-MCI) and from controls, i.e., patients with other neurological diseases (OND), were analyzed with the Olink Inflammation PEA biomarker panel. A machine-learning approach was then used to identify biomarkers discriminating AD-MCI (n: 34) from OND (n: 25). On univariate analysis, SIRT2, HGF, MMP-10, and CXCL5 showed high discriminatory performance (AUC 0.809, p = 5.2 × 10⁻⁴, AUC 0.802, p = 6.4 × 10⁻⁴, AUC 0.793, p = 3.2 × 10⁻³, AUC 0.761, p = 2.3 × 10⁻³, respectively), with higher CSF levels in AD-MCI patients as compared to controls. These same proteins were the best contributors to the penalized logistic regression model discriminating AD-MCI from controls (AUC of the model 0.906, p = 2.97 × 10⁻⁷). The biological processes regulated by these proteins include astrocyte and microglia activation, amyloid, and tau misfolding modulation, and blood-brain barrier dysfunction. Using a high-throughput multiplex CSF analysis coupled with a machine-learning statistical approach, we identified novel biomarkers reflecting neuroinflammation in AD. Studies confirming these results by means of different assays are needed to validate PEA as a multiplex technique for CSF analysis and biomarker discovery in the field of neurological diseases.

Altered Cytokine Response of Human Brain Endothelial Cells after Stimulation with Malaria Patient Plasma

Infections with the deadliest malaria parasite, Plasmodium falciparum, are accompanied by a strong immunological response of the human host. To date, more than 30 cytokines have been detected in elevated levels in plasma of malaria patients compared to healthy controls. Endothelial cells (ECs) are a potential source of these cytokines, but so far it is not known if their cytokine secretion depends on the direct contact of the P. falciparum-infected erythrocytes (IEs) with ECs in terms of cytoadhesion. Culturing ECs with plasma from malaria patients (27 returning travellers) resulted in significantly increased secretion of IL-11, CXCL5, CXCL8, CXCL10, vascular endothelial growth factor (VEGF) and angiopoietin-like protein 4 (ANGPTL4) if compared to matching controls (22 healthy individuals). The accompanying transcriptome study of the ECs identified 43 genes that were significantly increased in expression (≥1.7 fold) after co-incubation with malaria patient plasma, including cxcl5 and angptl4. Further bioinformatic analyses revealed that biological processes such as cell migration, cell proliferation and tube development were particularly affected in these ECs. It can thus be postulated that not only the cytoadhesion of IEs, but also molecules in the plasma of malaria patients exerts an influence on ECs, and that not only the immunological response but also other processes, such as angiogenesis, are altered.

Hsa-miR-605 regulates the proinflammatory chemokine CXCL5 in complex regional pain syndrome

Complex regional pain syndrome (CRPS) is a chronic pain condition characterized by inflammation and debilitating pain. CRPS patients with pain refractory to more conventional analgesics can be treated with subanesthetic doses of ketamine. Our previous studies found that poor responders to ketamine had a 22-fold downregulation of the miRNA hsa-miR-605 in blood prior to ketamine treatment. Hence, we sought to investigate the functional significance of miR-605 downregulation and its impact on target gene expression, as investigating target mRNAs of differentially expressed miRNAs can provide important insights on aberrant gene expression that may contribute to disease etiology. Using a bioinformatics prediction, we identified that miR-605 can target the proinflammatory chemokine CXCL5, which plays a role in leukocyte recruitment and activation. We hypothesized that downregulation of miR-605 in poor responders to ketamine could increase CXCL5 expression and thereby contribute to inflammation in these patients. We confirmed that miR-605 regulates CXCL5 by using a miRNA mimic and inhibitor in human primary endothelial cells. Inhibition of miR-605 increased CXCL5 secretion and migration of human monocytic cells, thereby demonstrating a functional impact of miR-605 on chemotaxis. Additionally, CXCL5 mRNA was upregulated in whole blood from poor responders to ketamine, and CXCL5 protein was increased in plasma from CRPS patients. Thus, our studies suggest that miR-605 regulation of CXCL5 can regulate inflammation.

Myeloid cell-derived HOCl is a paracrine effector that trans-inhibits IKK/NF-κB in melanoma cells and limits early tumor progression

The myeloperoxidase (MPO) system of myeloid-derived cells (MDCs) is central to cellular innate immunity. Upon MDC activation, MPO is secreted into phagosomes where it catalyzes the production of hypochlorous acid (HOCl), a potent chlorinating oxidant. Here, we demonstrated that the myeloid lineage-restricted MPO-HOCl system had antitumor effects in early melanoma growth in aged mice. Orthotopic melanomas grew more slowly in immunocompetent MPO^+/+ host mice compared to age-matched syngeneic MPO^-/- mice. Real-time intravital tumor imaging in vivo and in cell cocultures revealed a cell-cell proximity-dependent association between MDC-derived MPO enzyme activity and blockade of ligand-induced IκBα degradation in tumor cells. HOCl directly trans-inhibited IκB kinase (IKK) activity in tumor cells, thereby decreasing nuclear factor κB (NF-κB) transcriptional activation and inducing changes in the expression of genes involved in metabolic pathways, cell cycle progression, and DNA replication. By contrast, HOCl induced transcriptional changes in CD8⁺ T cells related to ion transport and the MAPK and PI3K-AKT signaling pathways that are associated with T cell activation. MPO increased the circulating concentrations of the myeloid cell-attracting cytokines CXCL1 and CXCL5, enhanced local infiltration by CD8⁺ cytotoxic T cells, and decreased tumor growth. Overall, these data reveal a role for MDC-derived HOCl as a small-molecule paracrine signaling factor that trans-inhibits IKK in melanoma tumor cells, mediating antitumor responses during early tumor progression.

The Impact of the CX3CL1/CX3CR1 Axis in Neurological Disorders

Fractalkine (FKN, CX3CL1) is a transmembrane chemokine expressed by neurons in the central nervous system (CNS). CX3CL1 signals through its unique receptor, CX3CR1, that is expressed in microglia. Within the CNS, fractalkine acts as a regulator of microglia activation in response to brain injury or inflammation. During the last decade, there has been a growing interest in the roles that the CX3CL1/CX3CR1 signaling pathway plays in the neuropathology of a diverse array of brain disorders. However, the reported results have proven controversial, indicating that a disruption of the CX3CL1 axis induces a disease-specific microglial response that may have either beneficial or detrimental effects. Therefore, it has become clear that the understanding of neuron-to-glia signals mediated by CX3CL1/CX3CR1 at different stages of diseases could provide new insight into potential therapeutic targets. Hence, the aim of this review is to provide a summary of the literature on the emerging role of CX3CL1 in animal models of some brain disorders.

A Collagen Based Cryogel Bioscaffold that Generates Oxygen for Islet Transplantation

The aim of this work was to develop, characterize and test a novel 3D bioscaffold matrix which can accommodate pancreatic islets and provide them with a continuous, controlled and steady source of oxygen to prevent hypoxia-induced damage following transplantation. Hence, we made a collagen based cryogel bioscaffold which incorporated calcium peroxide (CPO) into its matrix. The optimal concentration of CPO integrated into bioscaffolds was 0.25wt.% and this generated oxygen at 0.21±0.02mM/day (day 1), 0.19±0.01mM/day (day 6), 0.13±0.03mM/day (day 14), and 0.14±0.02mM/day (day 21). Accordingly, islets seeded into cryogel-CPO bioscaffolds had a significantly higher viability and function compared to islets seeded into cryogel alone bioscaffolds or islets cultured alone on traditional cell culture plates; these findings were supported by data from quantitative computational modelling. When syngeneic islets were transplanted into the epididymal fat pad (EFP) of diabetic mice, our cryogel-0.25wt.%CPO bioscaffold improved islet function with diabetic animals re-establishing glycemic control. Mice transplanted with cryogel-0.25wt.%CPO bioscaffolds showed faster responses to intraperitoneal glucose injections and had a higher level of insulin content in their EFP compared to those transplanted with islets alone (P<0.05). Biodegradability studies predicted that our cryogel-CPO bioscaffolds will have long-lasting biostability for approximately 5 years (biodegradation rate: 16.00±0.65%/year). Long term implantation studies (i.e. 6 months) showed that our cryogel-CPO bioscaffold is biocompatible and integrated into the surrounding fat tissue with minimal adverse tissue reaction; this was further supported by no change in blood parameters (i.e. electrolyte, metabolic, chemistry and liver panels). Our novel oxygen-generating bioscaffold (i.e. cryogel-0.25wt.%CPO) therefore provides a biostable and biocompatible 3D microenvironment for islets which can facilitate islet survival and function at extra-hepatic sites of transplantation.

A novel CXCL8-IP10 hybrid protein is effective in blocking pulmonary pathology in a mouse model of Klebsiella pneumoniae infection

Klebsiella pneumoniae (K. pneumoniae) is a hospital-acquired infectious agent that causes a range of diseases. Herein we have developed a novel CXCL8-IP10 hybrid protein and evaluated its efficacy in an animal model of K. pneumoniae infection. Neutrophil chemotaxis data revealed that CXCL8-IP10 could inhibit human neutrophil chemotactic responses induced by the ELR-CXC chemokine CXCL8. To evaluate the effect of CXCL8-IP10 on K. pneumoniae infection, C57BL/6 mice were challenged with K. pneumoniae followed by treatment with CXCL8-IP10 (500 μg/kg, i.p.), or dexamethasone (0.8 mg/kg, s.c.), or ceftazidime (200 mg/kg, s.c.) individually. CXCL8-IP10, dexamethasone or ceftazidime markedly inhibit Klebsiella-induced pulmonary inflammation as assessed by gross examination and histopathology. Moreover, the chemotactic responses of neutrophils was blocked by CXCL8-IP10 rather than dexamethasone or ceftazidime. Furthermore, the levels of inflammatory factors IL-1β, IFN-γ and TNF-α were decreased after CXCL8-IP10, dexamethasone or ceftazidime treatment. Together, these results suggest that CXCL8-IP10 may provide a novel strategy for treating K. pneumoniae infection.

Exacerbation and Prolongation of Psoriasiform Inflammation in Diabetic Obese Mice: A Synergistic Role of CXCL5 and Endoplasmic Reticulum Stress

Accumulating evidence suggests that psoriasis is frequently accompanied by metabolic disorders, such as obesity and diabetes. However, the mechanisms underlying the association between increased psoriasis severity and concomitant metabolic syndrome have not been fully clarified. Herein, we show that imiquimod-induced psoriasiform inflammation was exacerbated and prolonged in diabetic obese mice compared to that in control mice, accompanied by remarkably increased lesional expressions of Cxcl5 and Il-1b. Notably, a large number of CXCL5⁺ Ly6G⁺ cells infiltrated the dermis and subcutaneous fat tissue of the diabetic obese mice. Most macrophages in the subcutaneous fat tissues of the diabetic obese mice were positive for expression of IL-1β and GRP78/Bip, an endoplasmic reticulum stress marker. Depletion of Ly6G⁺ cells and macrophages diminished the imiquimod-induced psoriasiform inflammation. Further, CXCL5 potentiated the secretion of IL-1β from macrophages and palmitic acid, a fatty acid released from subcutaneous adipocytes, further enhanced IL-1β secretion via endoplasmic reticulum stress induction. Combined with the fact that the serum levels of both CXCL5 and palmitic acid are significantly elevated in patients with metabolic syndrome, our results suggest a role for CXCL5 and endoplasmic reticulum stress in the increase of psoriasis severity of patients with concomitant metabolic syndrome.

Blockade of the kinin B1 receptor affects the cytokine/chemokine profile in rat brain subjected to autoimmune encephalomyelitis

Kinins are bioactive peptides which provide multiple functions, including critical regulation of the inflammatory response. Released during tissue injury, kinins potentiate the inflammation which represents a hallmark of numerous neurological disorders, including those of autoimmune origin such as multiple sclerosis (MS). In the present work, we assess the expression of B1 receptor (B1R) in rat brain during the course of experimental autoimmune encephalomyelitis (EAE) which is an animal model of MS. We apply pharmacological inhibition to investigate the role of this receptor in the development of neurological deficits and in shaping the cytokine/chemokine profile during the course of the disease. Overexpression of B1R is observed in brain tissue of rats subjected to EAE, beginning at the very early asymptomatic phase of the disease. This overexpression is suppressed by a specific antagonist known as DALBK. The involvement of B1R in the progression of neurological symptoms in immunized rats is confirmed. Analysis of an array of cytokines/chemokines identified a sub-group as being B1R-dependent. Increase of the protein levels for the proinflammatory cytokines (Il-6, TNF-α but not IL-1β), chemokines attracting immune cells into nervous tissue (MCP-1, MIP-3α, LIX), and protein levels of fractalkine and vascular endothelial growth factor observed in EAE rats, were significantly diminished after DALBK administration. This may indicate the protective potential of pharmacological inhibition of B1R. However, simultaneously reduced protein levels of anti-inflammatory and neuroprotective factors (IL-10, IL-4, and CNTF) was noticed. The results show that B1R-mediated signaling regulates the cellular response profile following neuroinflammation in EAE.

Increased plasma levels of epithelial neutrophil-activating peptide 78/CXCL5 during the remission of Neuromyelitis optica

BACKGROUND

In neuromyelitis optica (NMO), one of the underlying pathogenic mechanisms is the formation of antigen-antibody complexes which can trigger an inflammatory response by inducing the infiltration of neutrophils in lesions. Epithelial neutrophil-activating peptide 78 (ENA 78), known as Chemokine (C-X-C motif) ligand 5 (CXCL5), belongs to the ELR-CXCL family. It recruits and activates neutrophils. The aim of this study was to evaluate ENA 78, IL-1β and TNF-α plasma levels in multiple sclerosis (MS) and neuromyelitis optica (NMO) patients.

METHODS

ENA 78, IL-1β and TNF-α plasma levels were detected in 20 healthy controls (HC), 25 MS and 25 NMO patients using MILLIPLEX® map Human High Sensitivity Cytokine/Chemokine Panels.

RESULTS

Plasma levels of ENA 78 were significantly higher in NMO patients than in HC (P < 0.001) and MS patients (P < 0.05). The NMO patients showed higher plasma levels of IL-1β compared with HC (P < 0.01). Further, increased plasma levels of TNF-α were found in the MS (P < 0.05) and NMO patients (P < 0.001). In addition, NMO patients had higher Expanded Disability Status Scale (EDSS) scores compared with MS patients (P < 0.05). EDSS scores were correlated with plasma levels of ENA 78 in NMO patients (P < 0.05). There were no significant correlations between EDSS scores and plasma levels of ENA 78 in MS patients (P > 0.05).

CONCLUSIONS

The overproduction of pro-inflammatory cytokines such as IL-1β and TNF-α during the remission of NMO activates ENA 78, which in turn leads to neutrophil infiltration in lesions. ENA 78 plasma levels were correlated with EDSS scores in NMO patients. Elevated secretion of ENA 78 may be a critical step in neutrophil recruitment during the remission of NMO.

Twin Attributes of Tyrosyl-tRNA Synthetase of Leishmania donovani: A HOUSEKEEPING PROTEIN TRANSLATION ENZYME AND A MIMIC OF HOST CHEMOKINE

Aminoacyl-tRNA synthetases (aaRSs) are housekeeping enzymes essential for protein synthesis. Apart from their parent aminoacylation activity, several aaRSs perform non-canonical functions in diverse biological processes. The present study explores the twin attributes of Leishmania tyrosyl-tRNA synthetase (LdTyrRS) namely, aminoacylation, and as a mimic of host CXC chemokine. Leishmania donovani is a protozoan parasite. Its genome encodes a single copy of tyrosyl-tRNA synthetase. We first tested the canonical aminoacylation role of LdTyrRS. The recombinant protein was expressed, and its kinetic parameters were determined by aminoacylation assay. To study the physiological role of LdTyrRS in Leishmania, gene deletion mutations were attempted via targeted gene replacement. The heterozygous mutants showed slower growth kinetics and exhibited attenuated virulence. LdTyrRS appears to be an essential gene as the chromosomal null mutants did not survive. Our data also highlights the non-canonical function of L. donovani tyrosyl-tRNA synthetase. We show that LdTyrRS protein is present in the cytoplasm and exits from the parasite cytoplasm into the extracellular medium. The released LdTyrRS functions as a neutrophil chemoattractant. We further show that LdTyrRS specifically binds to host macrophages with its ELR (Glu-Leu-Arg) peptide motif. The ELR-CXCR2 receptor interaction mediates this binding. This interaction triggers enhanced secretion of the proinflammatory cytokines TNF-α and IL-6 by host macrophages. Our data indicates a possible immunomodulating role of LdTyrRS in Leishmania infection. This study provides a platform to explore LdTyrRS as a potential target for drug development.

Inflammatory Serum Protein Profiling of Patients with Lumbar Radicular Pain One Year after Disc Herniation

Earlier studies suggest that lumbar radicular pain following disc herniation may be associated with a local or systemic inflammatory process. In the present study, we investigated the serum inflammatory protein profile of such patients. All 45 patients were recruited from Oslo University Hospital, Ullevål, Norway, during the period 2007–2009. The new multiplex proximity extension assay (PEA) technology was used to analyze the levels of 92 proteins. Interestingly, the present data showed that patients with radicular pain 12 months after disc herniation may be different from other patients with regard to many measurable serum cytokines. Given a false discovery rate (FDR) of 0.10 and 0.05, we identified 41 and 13 proteins, respectively, which were significantly upregulated in the patients with severe pain one year after disc herniation. On the top of the list ranked by estimated increase we found C-X-C motif chemokine 5 (CXCM5; 217% increase), epidermal growth factor (EGF; 142% increase), and monocyte chemotactic protein 4 (MCP-4; 70% increase). Moreover, a clear overall difference in the serum cytokine profile between the chronic and the recovered patients was demonstrated. Thus, the present results may be important for future protein serum profiling of lumbar radicular pain patients with regard to prognosis and choice of treatment. We conclude that serum proteins may be measurable molecular markers of persistent pain after disc herniation.

Chemokines and Heart Disease: A Network Connecting Cardiovascular Biology to Immune and Autonomic Nervous Systems

Among the chemokines discovered to date, nineteen are presently considered to be relevant in heart disease and are involved in all stages of cardiovascular response to injury. Chemokines are interesting as biomarkers to predict risk of cardiovascular events in apparently healthy people and as possible therapeutic targets. Moreover, they could have a role as mediators of crosstalk between immune and cardiovascular system, since they seem to act as a “working-network” in deep linkage with the autonomic nervous system. In this paper we will describe the single chemokines more involved in heart diseases; then we will present a comprehensive perspective of them as a complex network connecting the cardiovascular system to both the immune and the autonomic nervous systems. Finally, some recent evidences indicating chemokines as a possible new tool to predict cardiovascular risk will be described.

CXCL5 signaling is a shared pathway of neuroinflammation and blood-brain barrier injury contributing to white matter injury in the immature brain

Background

In very preterm infants, white matter injury is a prominent brain injury, and hypoxic ischemia (HI) and infection are the two primary pathogenic factors of this injury. Microglia and microvascular endothelial cells closely interact; therefore, a common signaling pathway may cause neuroinflammation and blood–brain barrier (BBB) damage after injury to the immature brain. CXC chemokine ligand 5 (CXCL5) is produced in inflammatory and endothelial cells by various organs in response to insults. CXCL5 levels markedly increased in the amniotic cavity in response to intrauterine infection and preterm birth in clinical studies. The objective of this study is to determine whether CXCL5 signaling is a shared pathway of neuroinflammation and BBB injury that contributes to white matter injury in the immature brain.

Methods

Postpartum day 2 (P2) rat pups received lipopolysaccharide (LPS) followed by 90-min HI. Immunohistochemical analyses were performed to determine microglial activation, neutrophil infiltration, BBB damage, and myelin basic protein and glial fibrillary acidic protein expression. Immunofluorescence experiments were performed to determine the cellular distribution of CXCL5. Pharmacological tests were performed to inhibit or enhance CXCL5 activity.

Results

On P2, predominant increases in microglial activation and BBB damage were observed 24 h after LPS-sensitized HI induction, and white matter injury (decreased myelination and increased astrogliosis) was observed on P12 compared with controls. Immunohistochemical analyses revealed increased CXCL5 expression in the white matter 6 and 24 h after insult. Immunofluorescence experiments revealed upregulated CXCL5 expression in the activated microglia and endothelial cells 24 h after insult. CXCL5 inhibition by SB225002, a selective nonpeptide inhibitor of CXCR2, significantly attenuated microglial activation and BBB damage, increased myelination, and reduced astrogliosis in the white matter after LPS-sensitized HI. In addition, CXCL5-sensitized HI or CXCL5 alone significantly induced BBB damage and white matter injury in association with different neuroinflammation mechanisms. CXCL5-sensitized HI-induced microglial activation and neutrophil infiltration, whereas CXCL5 alone predominately caused neutrophil infiltration.

Conclusions

CXCL5 is a potential biomarker for white matter injury in preterm infants. Pharmacological blockade of CXCL5 signaling that attenuates dysregulated neuroinflammation can be used a therapeutic strategy against white matter injury in the immature brain.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0474-6) contains supplementary material, which is available to authorized users.

Sensitivity of neural stem cell survival, differentiation and neurite outgrowth within 3D hydrogels to environmental heavy metals

We investigated the sensitivity of embryonic murine neural stem cells exposed to 10 pM-10 μM concentrations of three heavy metals (Cd, Hg, Pb), continuously for 14 days within 3D collagen hydrogels. Critical endpoints for neurogenesis such as survival, differentiation and neurite outgrowth were assessed. Results suggest significant compromise in cell viability within the first four days at concentrations ≥10 nM, while lower concentrations induced a more delayed effect. Mercury and lead suppressed neural differentiation at as low as 10 pM concentration within 7 days, while all three metals inhibited neural and glial differentiation by day 14. Neurite outgrowth remained unaffected at lower cadmium or mercury concentrations (≤100 pM), but was completely repressed beyond day 1 at higher concentrations. Higher metal concentrations (≥100 pM) suppressed NSC differentiation to motor or dopaminergic neurons. Cytokines and chemokines released by NSCs, and the sub-cellular mechanisms by which metals induce damage to NSCs have been quantified and correlated to phenotypic data. The observed degree of toxicity in NSC cultures is in the order: lead>mercury>cadmium. Results point to the use of biomimetic 3D culture models to screen the toxic effects of heavy metals during developmental stages, and investigate their underlying mechanistic pathways.

Therapeutic Effects of Umbilical Cord Blood Derived Mesenchymal Stem Cell-Conditioned Medium on Pulmonary Arterial Hypertension in Rats

Background:

Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) may have multiple therapeutic applications for cell based therapy including the treatment of pulmonary artery hypertension (PAH). As low survival rates and potential tumorigenicity of implanted cells could undermine the mesenchymal stem cell (MSC) cell-based therapy, we chose to investigate the use of conditioned medium (CM) from a culture of MSC cells as a feasible alternative.

Methods:

CM was prepared by culturing hUCB-MSCs in three-dimensional spheroids. In a rat model of PAH induced by monocrotaline, we infused CM or the control unconditioned culture media via the tail-vein of 6-week-old Sprague-Dawley rats.

Results:

Compared with the control unconditioned media, CM infusion reduced the ventricular pressure, the right ventricle/(left ventricle+interventricular septum) ratio, and maintained respiratory function in the treated animals. Also, the number of interleukin 1α (IL-1α), chemokine (C-C motif) ligand 5 (CCL5), and tissue inhibitor of metalloproteinase 1 (TIMP-1)–positive cells increased in lung samples and the number of terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling technique (TUNEL)–positive cells decreased significantly in the CM treated animals.

Conclusions:

From our in vivo data in the rat model, the observed decreases in the TUNEL staining suggest a potential therapeutic benefit of the CM in ameliorating PAH-mediated lung tissue damage. Increased IL-1α, CCL5, and TIMP-1 levels may play important roles in this regard.

Ex vivo exposure of bone marrow from chronic kidney disease donor rats to pravastatin limits renal damage in recipient rats with chronic kidney disease

Introduction

Healthy bone marrow cell (BMC) infusion improves renal function and limits renal injury in a model of chronic kidney disease (CKD) in rats. However, BMCs derived from rats with CKD fail to retain beneficial effects, demonstrating limited therapeutic efficacy. Statins have been reported to improve cellular repair mechanisms.

Methods

We studied whether exposing CKD rat BMCs ex vivo to pravastatin improved their in vivo therapeutic efficacy in CKD and compared this to systemic in vivo treatment. Six weeks after CKD induction, healthy BMCs, healthy pravastatin-pretreated BMCs, CKD BMCs or CKD pravastatin-pretreated BMCs were injected into the renal artery of CKD rats.

Results

At 6 weeks after BMC injection renal injury was reduced in pravastatin-pretreated CKD BMC recipients vs. CKD BMC recipients. Effective renal plasma flow was lower and filtration fraction was higher in CKD BMC recipients compared to all groups whereas there was no difference between pravastatin-pretreated CKD BMC and healthy BMC recipients. Mean arterial pressure was higher in CKD BMC recipients compared to all other groups. In contrast, 6 weeks of systemic in vivo pravastatin treatment had no effect. In vitro results showed improved migration, decreased apoptosis and lower excretion of pro-inflammatory Chemokine (C-X-C Motif) Ligand 5 in pravastatin-pretreated CKD BMCs.

Conclusions

Short ex vivo exposure of CKD BMC to pravastatin improves CKD BMC function and their subsequent therapeutic efficacy in a CKD setting, whereas systemic statin treatment did not provide renal protection.

The potential of CXCL5 as a target for liver cancer - what do we know so far?

CXCL5, epithelial cell derived neutrophil attractant 78, is a CXC chemokine predominantly expressed on epithelial cells. It has specificity for CXCR2 receptors and is involved in the recruitment and activation of neutrophils. CXCL5 is considered a therapeutic target in liver cancer, since treatment with small-interfering RNAs or antibodies against CXCL5 can suppress tumor growth, proliferation, migration and invasion. Experimental evidence demonstrated that CXCL5 antibodies could reduce the tumor growth and synergistically increase the efficiency of the tyrosine kinase inhibitor, Gefitinib, without the addition of toxicity. A number of challenges are encountered and should be considered during the development and clinical application of CXCL5 target-specific drugs. The specificity of CXCL5 as a therapeutic target for certain types and duration of cancer should be more carefully clarified, since it seems that CXCL5 is involved in many molecular pathways and crosstalk between targeted chemokines/receptors. The concept that CXCL5 serves as the therapeutic target for liver cancer was evidenced by preclinical studies, and is the beginning of CXCL5-based drug discovery and development.

Chemokines and squamous cancer of the head and neck: targets for therapeutic intervention?

The biological properties of squamous carcinoma cells are intimately regulated by a multitude of cytokines and growth factors; the most well studied of these include epidermal growth factor receptor agonists and members of the transforming growth factor-beta family. The recent explosion of research in the field of chemokine function as a mediator of tumor progression has led to the possibility that these small, immunomodulatory proteins also play key roles in squamous carcinogenesis and may, therefore, be potential targets for novel therapeutic approaches.

Electronegative low-density lipoprotein induces cardiomyocyte apoptosis indirectly through endothelial cell-released chemokines

Cardiomyocyte apoptosis has a critical role in the pathogenesis of heart failure. L5, the most negatively charged subfraction of human plasma low-density lipoprotein (LDL), induces several atherogenic responses in endothelial cells (ECs), including apoptosis. We hypothesized that L5 also contributes to cardiomyocyte apoptosis and studied whether it does so indirectly by inducing the secretion of factors from ECs. We examined apoptosis of rat cardiomyocytes treated with culture-conditioned medium (CCM) of rat ECs that were exposed to L5 or L1 (the least negatively charged LDL subfraction). Apoptosis at early and late time points was twofold greater in cardiomyocytes treated with L5 CCM than in those treated with L1 CCM. The indirect effect of L5 on cardiomyocyte apoptosis was significantly reduced by pretreating ECs with inhibitors of phosphatidylinositol 3-kinase (PI3K) or CXC receptor 2 (CXCR2). Studies with cytokine protein arrays revealed that L5 CCM, but not L1 CCM, contained high levels of ELR(+) CXC chemokines, including lipopolysaccharide-induced chemokine (LIX) and interleukin (IL)-8. The L5-induced release of these chemokines from ECs was abolished by inhibiting the lectin-like oxidized LDL receptor-1 (LOX-1). Addition of recombinant LIX or IL-8 to CCM-free cardiomyocyte cultures increased apoptosis and enhanced production of tumor necrosis factor (TNF)-α and IL-1β by increasing the translocation of NF-κB into the nucleus; these effects were attenuated by inhibiting PI3K and CXCR2. In conclusion, L5 may indirectly induce cardiomyocyte apoptosis by enhancing secretion of ELR(+) CXC chemokines from ECs, which in turn activate CXCR2/PI3K/NF-κB signaling to increase the release of TNF-α and IL-1β.

Characterization of polarized THP-1 macrophages and polarizing ability of LPS and food compounds

Little is known about the polarizing potential of currently used human macrophage cell lines, while a better understanding phenomena can support the prediction of effects in vivo based on in vitro analysis. To test the polarization capability of PMA differentiated-THP-1 macrophages (M0), cells were stimulated with 20 ng ml(-1) IFNγ + 1 μg ml(-1) LPS and 20 ng ml(-1) IL-4, which are known to influence macrophage polarization in vivo and ex vivo into the M1 and M2 state, respectively. Apart from several well-known M1 and M2 markers, also new possible markers for M1 and M2 polarization were analysed in this study. The expression of M1 marker genes was up-regulated in IFNγ + LPS stimulated-M0 THP-1 macrophages. The IL-4 stimulated-M0 THP-1 macrophages expressed M2 cell membrane receptor genes. However, M2 chemokine and their receptor genes were only slightly up-regulated which might be due to the complexity of the secondary cell-cell interaction of the chemokine system. Lipopolysaccharides from E. coli (LPS) and food compounds [lentinan, vitamin D3 (vD3) and the combination of lentinan + vitamin D3 (Len + vD3)] were investigated for their polarizing ability on M0 THP-1 macrophages towards either the M1 or M2 state. LPS (700 ng ml(-1)) was able to skew M0 THP-1 macrophages towards the M1 direction since all analysed M1 marker genes were strongly expressed. Lentinan, vD3 and Len + vD3 did not induce expression of either M1 or M2 markers, indicating no polarizing ability of these compounds. Based on the expression of M1 and M2 marker genes we concluded that THP-1 macrophages could be successfully polarized into either the M1 or M2 state. Therefore, they can be used as a new macrophage polarizing model to estimate the polarizing/switching ability of test food compounds.

Isolation and characterization of muscle fatigue substance with anti-tumor activities

Research during the 1950's indicated that exercise played a role in the reduction of tumor growth. In the 1960's our studies confirmed that tumor-bearing rats, exercised to fatigue, demonstrated tumor inhibition. Our further studies isolated an extract (Fatigue Substance, or F-Substance) from rectus femoris muscles of rats which had been electrically stimulated to fatigue. This extract significantly inhibited growth of transplanted rat tumors. Research continued until 1978 when it became apparent the methodology at that time was not able to further identify the substance's active components. Using current technology, we now report on the further isolation and characterization of F-Substance. In cell proliferation assays, extracts from electrically stimulated rat rectus femoris muscles had more significant inhibitory effect on the breast cancer cell line MCF-7 than those isolated from unstimulated muscles. To identify the molecule(s) responsible for the antitumor activity, a rat cytokine antibody array was used to profile the cytokines in the substances. Among the 29 different cytokines contained on the array, 3 showed greater than 3-fold difference between the substances isolated from the stimulated and unstimulated muscles. LIX (also known as CXCL5) is 6-fold higher in the substances isolated from stimulated muscles than those from the unstimulated muscles. TIMP-1 is 4.6 fold higher and sICAM is 3.6 fold higher in the substances from the stimulated muscles. Our results indicated that cytokines released from contracting muscles might be responsible for the antitumor effect of F-Substance.

CXCR4 Antagonist AMD3100 Protects Blood–Brain Barrier Integrity and Reduces Inflammatory Response After Focal Ischemia in Mice

Background and Purpose—

Inflammatory response plays a critical role in propagating tissue damage after focal cerebral ischemia. CXCL12 is a key chemokine for leukocyte recruitment. However, the role of CXCL12 and its receptor CXCR4 in ischemia-induced inflammatory response is unclear. Here we use the pharmacological antagonist of CXCR4, AMD3100, to investigate the function of CXCL12/CXCR4 in regulating inflammatory response during acute ischemia.

Methods—

Adult male CD-1 mice (n=184) underwent permanent suture middle cerebral artery occlusion (MCAO). AMD3100 was injected for 3 days (1 mg/kg/day) after MCAO. Brain water content, infarct volume, neurological score, and myeloperoxidase (MPO) expression and activity were examined at 24, 48, and 72 hours after MCAO. Proinflammatory cytokine RNA and protein levels in brain tissue were measured by RT-PCR and enzyme linked immunosorbent assay.

Results—

Neurological score was greatly improved in AMD3100-treated mice compared with the control mice 3 days after MCAO ( P <0.05). Brain edema–induced change of water content, IgG protein leakage, Evans blue extravasation, occludin, and ZO-1 expression in ipsilateral hemisphere were alleviated by acute treatment of AMD3100. MPO expression and activity revealed that AMD3100 profoundly reduced the number of MPO-positive cells in the ischemic region ( P <0.05). It also attenuated proinflammatory cytokines including interleukin 6, tumor necrosis factor α, and interferon γ; their mRNA and protein levels changed accordingly compared with the controls ( P <0.05).

Conclusions—

CXCR4 antagonist AMD3100 significantly suppressed inflammatory response and reduced blood–brain barrier disruption after MCAO. AMD3100 attenuated ischemia-induced acute inflammation by suppressing leukocyte migration and infiltration, in addition to reducing proinflammatory cytokine expression in the ischemic region.

Acute inducible ablation of GRP78 reveals its role in hematopoietic stem cell survival, lymphogenesis and regulation of stress signaling

GRP78, a master regulator of the unfolded protein response (UPR) and cell signaling, is required for inner cell mass survival during early embryonic development. However, little is known about its role in adult hematopoietic stem cells (HSCs) and hematopoiesis. Here we generated a conditional knockout mouse model that acutely deletes Grp78 in the adult hematopoietic system. Acute GRP78 ablation resulted in a significant reduction of HSCs, common lymphoid and myeloid progenitors, and lymphoid cell populations in the mutant mice. The GRP78-null induced reduction of the HSC pool could be attributed to increased apoptosis. Chimeric mice with Grp78 deletion only in the hematopoietic cells also showed a loss of HSCs and lymphopenia, suggesting a cell intrinsic effect. Analysis of GRP78 deficient bone marrow (BM) cells showed constitutive activation of all the major UPR signaling pathways, including activation of eIF2α, ATF6, xbp-1 splicing, as well as caspase activation. A multiplex cytokine assay further revealed alteration in select cytokine and chemokine serum levels in the mutant mice. Collectively, these studies demonstrate that GRP78 plays a pleiotropic role in BM cells and contributes to HSC survival and the maintenance of the lymphoid lineage.

Carboxylate microsphere-induced cellular toxicity in human lung fibroblasts

Carboxylate microspheres (CMs) are mainly used in industrial, biomedical and various household products. In this study, we assessed the cytotoxic effects of CMs on human MRC-5 lung fibroblasts by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Oxidative stress was determined by measurements of reactive oxygen species and antioxidant (superoxide dismutase and catalase) levels and proinflammatory cytokines quantified by enzyme-linked immunosorbent assay. Morphological changes were examined by light microscopy, confocal microscopy and transmission electron microscopy. The lung fibroblasts were exposed to increasing concentrations of CMs (0.1–1000 μmol/L) for 24 h. The results showed significant changes in cell morphology with induction of cytotoxicity and oxidative stress observed in 10–1000 μmol/L concentrations of CM-treated fibroblasts. Ultrastructural examination revealed the presence of CMs inside the cytoplasm of treated lung fibroblasts. CMs also induced elevated interleukin (IL)-1, IL-6, IL-8, IL-10 and tumor necrosis factor α levels at higher concentrations. We have demonstrated that CMs significantly reduce cell viability in a dose-dependant manner in lung fibroblasts at 0.1–1000 μmol/L doses. The findings suggest that high doses of CMs have the potential to induce cellular toxicity to the lung in vitro.

Upregulation of C-X-C chemokine receptor type 1 expression is associated with late-stage gastric adenocarcinoma

Chemokine receptors play multiple roles in the development and progression of various tumor types. The aim of this study was to examine C-X-C chemokine receptor type 1 (CXCR1) protein expression in gastric adenocarcinoma and to investigate the clinical implications of CXCR1 upregulation. Expression of CXCR1 protein in 83 specimens of sporadic gastric adenocarcinoma and their corresponding non-neoplastic mucosa obtained by gastrectomy was assayed using immunohistochemistry. The intensity of immunostaining in tumor tissue was considered strong when tumor tissue staining was more intense than in the corresponding non-neoplastic mucosa; the intensity was null when staining was weaker in the tumor than in the corresponding non-neoplastic mucosa; and the intensity was weak when staining was similar in both tissues. Microvascular density in tumor tissue and its corresponding non-neoplastic mucosa was measured using monoclonal antibody against CD34. A strong correlation was observed between elevated CXCR1 protein expression and tumor stage (P<0.05). T stage, N stage and overall stage positively correlated with CXCR1 protein expression. Microvascular density was higher in tumors with strong CXCR1 protein expression, but the correlation with CXCR1 was not linear (P=0.07). Multiple logistic regression analyses showed that, compared to no or weak expression, overexpression of CXCR1 protein was a significant risk factor for high N stage (N2, N3). These results indicate that CXCR1 may be considered as a new and promising target for gastric adenocarcinoma therapy.

Virus-infected alveolar epithelial cells direct neutrophil chemotaxis and inhibit their apoptosis

The alveolar epithelium is a critical target for pulmonary viruses and can produce proinflammatory cytokines and chemokines upon viral infection. However, the molecular interactions between virus-infected alveolar epithelial cells and inflammatory cells, including polymorphonuclear leukocytes (PMNs), have not been thoroughly characterized. Rat coronavirus (RCoV) is used as a model to study the immune response to viral infection in the lung of the natural host. We have developed an in vitro model to characterize the response of PMNs to RCoV-infected type I-like alveolar epithelial (AT1) cells, the primary target for RCoV infection in the alveoli. Multiple CXC chemokines that signal through CXCR2 were required for PMN chemotaxis toward medium from RCoV-infected AT1-like cells (RCoV-AT1). Furthermore, RCoV-AT1 inhibited spontaneous PMN apoptosis, including activation of effector caspase 3 and initiator caspases 8 and 9. Use of a selective inhibitor of CXCR2, SB265610, demonstrated that CXCR2 signaling was required for RCoV-AT1-mediated inhibition of PMN apoptosis. These data suggest that CXC chemokines produced by RCoV-infected AT1-like cells inhibit PMN apoptosis during infection. These studies provide new insight into the molecular mechanisms whereby alveolar epithelial cells direct the functions of PMNs during viral infection of the lung.

CXCL5 mediates UVB irradiation-induced pain

Many persistent pain states (pain lasting for hours, days, or longer) are poorly treated because of the limitations of existing therapies. Analgesics such as nonsteroidal anti-inflammatory drugs and opioids often provide incomplete pain relief and prolonged use results in the development of severe side effects. Identification of the key mediators of various types of pain could improve such therapies. Here, we tested the hypothesis that hitherto unrecognized cytokines and chemokines might act as mediators in inflammatory pain. We used ultraviolet B (UVB) irradiation to induce persistent, abnormal sensitivity to pain in humans and rats. The expression of more than 90 different inflammatory mediators was measured in treated skin at the peak of UVB-induced hypersensitivity with custom-made polymerase chain reaction arrays. There was a significant positive correlation in the overall expression profiles between the two species. The expression of several genes [interleukin-1β (IL-1β), IL-6, and cyclooxygenase-2 (COX-2)], previously shown to contribute to pain hypersensitivity, was significantly increased after UVB exposure, and there was dysregulation of several chemokines (CCL2, CCL3, CCL4, CCL7, CCL11, CXCL1, CXCL2, CXCL4, CXCL7, and CXCL8). Among the genes measured, CXCL5 was induced to the greatest extent by UVB treatment in human skin; when injected into the skin of rats, CXCL5 recapitulated the mechanical hypersensitivity caused by UVB irradiation. This hypersensitivity was associated with the infiltration of neutrophils and macrophages into the dermis, and neutralizing the effects of CXCL5 attenuated the abnormal pain-like behavior. Our findings demonstrate that the chemokine CXCL5 is a peripheral mediator of UVB-induced inflammatory pain, likely in humans as well as rats.

Anti-CXCL5 therapy ameliorates IL-17-induced arthritis by decreasing joint vascularization

IL-17-induced joint inflammation is associated with increased angiogenesis. However, the mechanism by which IL-17 mediates angiogenesis is undefined. Therefore, the pathologic role of CXCL1 and CXCL5 was investigated in arthritis mediated by local expression of IL-17, employing a neutralizing antibody to each chemokine. Next, endothelial chemotaxis was utilized to examine whether endothelial migration was differentially mediated by CXCL1 and CXCL5. Our results demonstrate that IL-17-mediated disease activity was not affected by anti-CXCL1 treatment alone. In contrast, mice receiving anti-CXCL5 demonstrated significantly reduced clinical signs of arthritis, compared to the mice treated with IgG control. Consistently, while inflammation, synovial lining thickness, bone erosion and vascularization were markedly reduced in both the anti-CXCL5 and combination anti-CXCL1 and 5 treatment groups, mice receiving anti-CXCL1 antibody had clinical scores similar to the control group. In contrast to joint FGF2 and VEGF levels, TNF-α was significantly reduced in mice receiving anti-CXCL5 or combination of anti-CXCL1 and 5 therapies compared to the control group. We found that, like IL-17, CXCL1-induced endothelial migration is mediated through activation of PI3K. In contrast, activation of NF-κB pathway was essential for endothelial chemotaxis induced by CXCL5. Although CXCL1 and CXCL5 can differentially mediate endothelial trafficking, blockade of CXCR2 can inhibit endothelial chemotaxis mediated by either of these chemokines. These results suggest that blockade of CXCL5 can modulate IL-17-induced inflammation in part by reducing joint blood vessel formation through a non-overlapping IL-17 mechanism.

Peroxisome proliferator-activated receptor-gamma ligands 15-deoxy-delta(12,14)-prostaglandin J2 and pioglitazone inhibit hydroxyl peroxide-induced TNF-alpha and lipopolysaccharide-induced CXC chemokine expression in neonatal rat cardiac myocytes

Ligands for peroxisome proliferator-activated receptor gamma (PPAR-gamma) such as prostaglandin metabolite 15-deoxy-delta(12,14)-prostaglandin J2 (15d-PGJ2) or thiazolidinedione pioglitazone have been identified as a new class of anti-inflammatory compounds with possible clinical applications. Reactive oxygen species play an important role in the generation of cellular damage by induction of proinflammatory cytokines and chemokines during myocardial I/R. These events were preceded by activation of the transcription factors nuclear factor (NF)-kappaB pathway. It has been suggested that myocardium overproduces TNF-alpha after I/R, and locally produced TNF-alpha is sufficient to cause severe impairment of cardiac function. LPS-induced CXC chemokine (LIX) is a rodent chemokine with potent neutrophil-chemotactic activity. Based on this concept, we examined the effects of 15d-PGJ2 and pioglitazone on oxidative stress-induced TNF-alpha and LIX expression in neonatal rat cardiac myocytes. Pretreatment of myocytes with 15d-PGJ2 or pioglitazone decreased hydrogen peroxide-induced TNF-alpha and LIX production (mRNA and protein) in a concentration-dependent manner. The beneficial effects of both ligands were associated with reduction of hydrogen peroxide-induced NF-kappaB activation. Treatment with 15d-PGJ2, but not pioglitazone, caused dose-dependent activation of heat shock factor 1, which could render cells unresponsive to stimulation of NF-kappaB. The cytoprotection afforded by pioglitazone was attenuated by the PPAR-gamma antagonist GW9662, which failed to affect the beneficial effects afforded by 15d-PGJ2. Taken together, these results demonstrate that treatment with these chemically distinct ligands of PPAR-gamma results in diverse anti-inflammatory mechanisms.

Febrile-range temperature modifies cytokine gene expression in LPS-stimulated macrophages by differentially modifying NF-{kappa}B recruitment to cytokine gene promoters

We previously showed that exposure to febrile-range temperatures (FRT, 39.5-40 degrees C) reduces LPS-induced TNF-alpha expression, in part through the direct interaction of heat shock factor-1 (HSF1) with the TNF-alpha gene promoter. However, it is not known whether exposure to FRT also modifies more proximal LPS-induced signaling events. Using HSF1-null mice, we confirmed that HSF1 is required for FRT-induced repression of TNF-alpha in vitro by LPS-stimulated bone marrow-derived macrophages and in vivo in mice challenged intratracheally with LPS. Exposing LPS-stimulated RAW 264.7 mouse macrophages to FRT reduced TNF-alpha expression while increasing IL-1beta expression despite the two genes sharing a common myeloid differentiation protein-88 (MyD88)-dependent pathway. Global activation of the three LPS-induced signaling intermediates that lead to cytokine gene expression, ERK and p38 MAPKs and NF-kappaB, was not affected by exposing RAW 264.7 cells to FRT as assessed by ERK and p38 phosphorylation and NF-kappaB in vitro DNA-binding activity and activation of a NF-kappaB-dependent synthetic promoter. However, chromatin immunoprecipitation (ChIP) analysis demonstrated that exposure to FRT reduced LPS-induced recruitment of NF-kappaB p65 to the TNF-alpha promoter while simultaneously increasing its recruitment to the IL-1beta promoter. These data suggest that FRT exerts its effects on cytokine gene expression in a gene-specific manner through distal effects on promoter activation rather than proximal receptor activation and signal transduction.

A crucial role for TNF-alpha in mediating neutrophil influx induced by endogenously generated or exogenous chemokines, KC/CXCL1 and LIX/CXCL5

BACKGROUND AND PURPOSE

Chemokines orchestrate neutrophil recruitment to inflammatory foci. In the present study, we evaluated the participation of three chemokines, KC/CXCL1, MIP-2/CXCL2 and LIX/CXCL5, which are ligands for chemokine receptor 2 (CXCR2), in mediating neutrophil recruitment in immune inflammation induced by antigen in immunized mice.

EXPERIMENTAL APPROACH

Neutrophil recruitment was assessed in immunized mice challenged with methylated bovine serum albumin, KC/CXCL1, LIX/CXCL5 or tumour necrosis factor (TNF)-alpha. Cytokine and chemokine levels were determined in peritoneal exudates and in supernatants of macrophages and mast cells by elisa. CXCR2 and intercellular adhesion molecule 1 (ICAM-1) expression was determined using immunohistochemistry and confocal microscopy.

KEY RESULTS

Antigen challenge induced dose- and time-dependent neutrophil recruitment and production of KC/CXCL1, LIX/CXCL5 and TNF-alpha, but not MIP-2/CXCL2, in peritoneal exudates. Neutrophil recruitment was inhibited by treatment with reparixin (CXCR1/2 antagonist), anti-KC/CXCL1, anti-LIX/CXCL5 or anti-TNF-alpha antibodies and in tumour necrosis factor receptor 1-deficient mice. Intraperitoneal injection of KC/CXCL1 and LIX/CXCL5 induced dose- and time-dependent neutrophil recruitment and TNF-alpha production, which were inhibited by reparixin or anti-TNF-alpha treatment. Macrophages and mast cells expressed CXCR2 receptors. Increased macrophage numbers enhanced, while cromolyn sodium (mast cell stabilizer) diminished, LIX/CXCL5-induced neutrophil recruitment. Macrophages and mast cells from immunized mice produced TNF-alpha upon LIX/CXCL5 stimulation. Methylated bovine serum albumin induced expression of ICAM-1 on mesenteric vascular endothelium, which was inhibited by anti-TNF-alpha or anti-LIX/CXCL5.

CONCLUSION AND IMPLICATIONS

Following antigen challenge, CXCR2 ligands are produced and act on macrophages and mast cells triggering the production of TNF-alpha, which synergistically contribute to neutrophil recruitment through induction of the expression of ICAM-1.

NF-kappaB mediated enhancement of potassium currents by the chemokine CXCL1/growth related oncogene in small diameter rat sensory neurons

Background

Inflammatory processes play important roles in both neuropathic and inflammatory pain states, but the effects of inflammation per se within the sensory ganglia are not well understood. The cytokine growth-related oncogene (GRO/KC; CXCL1) shows strong, rapid upregulation in dorsal root ganglion (DRG) in both nerve injury and inflammatory pain models. We examined the direct effects of GRO/KC on small diameter DRG neurons, which are predominantly nociceptive. Whole cell voltage clamp technique was used to measure voltage-activated potassium (K) currents in acutely cultured adult rat small diameter sensory neurons. Fluorescently labeled isolectin B4 (IB4) was used to classify cells as IB4-positive or IB4-negative.

Results

In IB4-negative neurons, voltage-activated K current densities of both transient and sustained components were increased after overnight incubation with GRO/KC (1.5 nM), without marked changes in voltage dependence or kinetics. The average values for the slow and fast decay time constants at 20 mV were unchanged by GRO/KC. The amplitude of the fast inactivating component increased significantly with no large shifts in the voltage dependence of inactivation. The increase in K currents was completely blocked by co-incubation with protein synthesis inhibitor cycloheximide (CHX) or NF-κB inhibitors pyrrolidine dithiocarbamate (PDTC) or quinazoline (6-Amino-4-(4-phenoxypheny lethylamino;QNZ). In contrast, the voltage-activated K current of IB4-positive neurons was unchanged by GRO/KC. GRO/KC incubation caused no significant changes in the expression level of eight selected voltage-gated K channel genes in quantitative PCR analysis.

Conclusion

The results suggest that GRO/KC has important effects in inflammatory processes via its direct actions on sensory neurons, and that activation of NF-κB is involved in the GRO/KC-induced enhancement of K currents.

Diet-induced adiposity alters the serum profile of inflammation in C57BL/6N mice as measured by antibody array

Morbid obesity is considered a systemic inflammatory state. The objective of this project was to characterize the adipokine, cytokine and chemokine protein profile in serum from control, lean and obese mice. We hypothesized that chemokines and cytokines are altered by caloric restriction and diet-induced obesity as a function of changes in body composition. Six-week-old female C57BL/6N mice (n = 12 per group) were randomized to one of three diets: control (fed ad libitum); lean (30% calorie-restricted regimen relative to control) and diet-induced obese (DIO; high calorie diet, fed ad libitum). Body weight, body composition and food intake were monitored throughout the study. After 10 weeks on the diets, blood samples were collected, and adipokine/cytokine/chemokine serum profiles were measured by antibody array. Lean mice, relative to the control group, displayed increased concentrations of insulin-like growth factor (IGF) binding protein-3, -5 and -6 and adiponectin and decreased IGF-1. These mice also showed increased concentrations of interleukin (IL)-10, IL-12 p40/p70, eotaxin, monocyte chemoattractant protein-5 and SDF-1. In contrast, DIO mice displayed increased leptin, IL-6 and LPS-induced chemokine and decreased concentrations of all chemokines/cytokines measured relative to control mice. As such, these data indicate that DIO may lead to an inflammatory state characterized as a shift towards a T helper lymphocyte type 1-skewed responsiveness. The demonstration of differential adipokine, cytokine and chemokine protein profile in control, lean and DIO mice may have implications for immune responsiveness and risk of disease.

Protective immunity to Mycobacterium tuberculosis infection by chemokine and cytokine conditioned CFP-10 differentiated dendritic cells

Background

Dendritic cells (DCs) play major roles in mediating immune responses to mycobacteria. A crucial aspect of this is the priming of T cells via chemokines and cytokines. In this study we investigated the roles of chemokines RANTES and IP-10 in regulating protective responses from Mycobacterium tuberculosis (M. tb) 10 kDa Culture Filtrate Protein-10 (CFP-10) differentiated DCs (CFP10-DCs).

Methods and Findings

Infection of CFP10-DCs with mycobacteria down-modulated RANTES and IP-10 levels. Pathway specific microarray analyses showed that in addition to RANTES and IP-10, mycobacteria infected CFP10-DCs showed reduced expression of many Th1 promoting chemokines and chemokine receptors. Importantly, T cells co-cultured with RANTES and IP-10 conditioned CFP10-DCs mediated killing of mycobacteria from infected macrophages. Similarly, T cells recruited by RANTES and IP-10 conditioned CFP10-DCs mediated significant killing of mycobacteria from infected macrophages. IFN-gamma treatment of CFP10-DCs restored RANTES and IP-10 levels and T cells activated by these DCs mediated significant killing of virulent M. tb inside macrophages. Adoptive transfer of either RANTES and IP-10 or IL-12 and IFN-gamma conditioned CFP10-DCs cleared an established M. tb infection in mice. The extent of clearance was similar to that obtained with drug treatment.

Conclusions

These results indicate that chemokine and cytokine secretion by DCs differentiated by M. tb antigens such as CFP-10 play major roles in regulating protective immune responses at sites of infection.

The selective nonpeptide CXCR2 antagonist SB225002 ameliorates acute experimental colitis in mice

Although neutrophils are strongly implicated in eliminating pathogens, excessive recruitment may cause tissue damage. Therefore, reducing cell influx during an inflammatory process may be a potential target for treating inflammatory bowel diseases (IBD). As CXCR2 is involved in neutrophil migration, this study aimed to evaluate whether the systemic therapeutic treatment with selective CXCR2 antagonist SB225002 ameliorates experimental colitis, which was induced in mice by 2,4,6-trinitrobenzene sulfonic acid (TNBS). After colitis establishment (24 h), mice were treated with SB225002. At later time-points, up to 72 h, mice were monitored for body weight loss and overall mortality. At the time of sacrifice, colonic tissues were scored for macro- and microscopic damage, and cytokine levels, myeloperoxidase (MPO) activity, and protein expression were analyzed. TNBS administration induced macro- and microscopic damage in colon tissue, leading in most cases to animal death. Curative treatment with SB225002 significantly reduced all of the parameters analyzed, leading to an improvement of inflammatory signs. SB225002 reduced neutrophil influx, MPO activity, IL-1beta, MIP-2, and keratinocyte-derived chemokine (KC) levels and the expression of vascular endothelial growth factor, inducible NO synthase, and cyclooxygenase-2 proteins into the colon tissue. Levels of IL-4 and IL-10 were increased significantly in the colons of animals treated with SB225002. Additionally, curative treatment with mouse anti-KC significantly reduced MPO activity and colonic damage. These results taken together demonstrate that a selective blockade of CXCR2 consistently reduced TNBS-induced colitis, suggesting that the use of SB225002 is a potential therapeutic approach for the treatment of IBD and other related inflammatory disorders.

Disrupted expression of CXCL5 in colorectal cancer is associated with rapid tumor formation in rats and poor prognosis in patients

PURPOSE

We isolated a subline (CC531M) from the CC531S rat colon carcinoma cell line, which grows and metastasizes much more rapidly than CC531S. We found, using RNA expression profiling, that one of the major changes in the CC531M cell line was a 5.8-fold reduction of the chemokine CXCL5. The purpose of this study was to determine the effect of CXCL5 expression on colorectal tumor growth and metastasis.

EXPERIMENTAL DESIGN

CC531 clones were generated with either knockdown or restored expression of CXCL5. These clones were inoculated in the liver of rats. In addition, in two independent cohorts of colorectal cancer patients, the level of CXCL5 expression was determined and associated to clinical variables.

RESULTS

Knockdown of CXCL5 expression in CC531S resulted in rapid tumor growth and increased number of metastasis, whereas restored expression of CXCL5 in CC531M resulted in a return of the "mild" tumor growth pattern of the parental cell line CC531S. In vitro, no difference was found in proliferation rate between clones with either high or low expression of CXCL5, suggesting that environmental interactions directed by CXCL5 determine tumor outgrowth. Finally, the importance of our findings was established for patients with colorectal cancer. We found that low expression of CXCL5 was significantly associated with poor prognosis for colorectal cancer patients. CXCL5 showed a trend (P = 0.05) for a positive correlation with intratumoral CD8(+) T-cell infiltration, suggesting a possible explanation for the observed poorer prognosis.

CONCLUSIONS

Our results show that CXCL5 is important in growth and development of colorectal cancer, implicating a future role in both cancer therapy and diagnosis.

Characterization of the acute temporal changes in excisional murine cutaneous wound inflammation by screening of the wound-edge transcriptome

This work represents a maiden effort to systematically screen the transcriptome of the healing wound-edge tissue temporally using high-density GeneChips. Changes during the acute inflammatory phase of murine excisional wounds were characterized histologically. Sets of genes that significantly changed in expression during healing could be segregated into the following five sets: up-early (6-24 h; cytokine-cytokine receptor interaction pathway), up-intermediary (12-96 h; leukocyte-endothelial interaction pathway), up-late (48-96 h; cell-cycle pathway), down-early (6-12 h; purine metabolism) and down-intermediary (12-96 h; oxidative phosphorylation pathway). Results from microarray and real-time PCR analyses were consistent. Results listing all genes that were significantly changed at any specific time point were further mined for cell-type (neutrophils, macrophages, endothelial, fibroblasts, and pluripotent stem cells) specificity. Candidate genes were also clustered on the basis of their functional annotation, linking them to inflammation, angiogenesis, reactive oxygen species (ROS), or extracellular matrix (ECM) categories. Rapid induction of genes encoding NADPH oxidase subunits and downregulation of catalase in response to wounding is consistent with the fact that low levels of endogenous H2O2 is required for wound healing. Angiogenic genes, previously not connected to cutaneous wound healing, that were induced in the healing wound-edge included adiponectin, epiregulin, angiomotin, Nogo, and VEGF-B. This study provides a digested database that may serve as a valuable reference tool to develop novel hypotheses aiming to elucidate the biology of cutaneous wound healing comprehensively.

Nanofibrous scaffolds incorporating PDGF-BB microspheres induce chemokine expression and tissue neogenesis in vivo

Platelet-derived growth factor (PDGF) exerts multiple cellular effects that stimulate wound repair in multiple tissues. However, a major obstacle for its successful clinical application is the delivery system, which ultimately controls the in vivo release rate of PDGF. Polylactic-co-glycolic acid (PLGA) microspheres (MS) in nanofibrous scaffolds (NFS) have been shown to control the release of rhPDGF-BB in vitro. In order to investigate the effects of rhPDGF-BB release from MS in NFS on gene expression and enhancement of soft tissue engineering, rhPDGF-BB was incorporated into differing molecular weight (MW) polymeric MS. By controlling the MW of the MS over a range of 6.5 KDa–64 KDa, release rates of PDGF can be regulated over periods of weeks to months in vitro. The NFS-MS scaffolds were divided into multiple groups based on MS release characteristics and PDGF concentration ranging from 2.5–25.0 µg and evaluated in vivo in a soft tissue wound repair model in the dorsa of rats. At 3, 7, 14 and 21 days post-implantation, the scaffold implants were harvested followed by assessments of cell penetration, vasculogenesis and tissue neogenesis. Gene expression profiles using cDNA microarrays were performed on the PDGF-releasing NFS. The percentage of tissue invasion into MS-containing NFS at 7 days was higher in the PDGF groups when compared to controls. Blood vessel number in the HMW groups containing either 2.5 or 25 µg PDGF was increased above those of other groups at 7d (p<0.01). Results from cDNA array showed that PDGF strongly enhanced in vivo gene expression of the CXC chemokine family members such as CXCL1, CXCL2 and CXCL5. Thus, sustained release of rhPDGF-BB, controlled by slow-releasing MS associated with the NFS delivery system, enhanced cell migration and angiogenesis in vivo, and may be related to an induced expression of chemokine-related genes. This approach offers a technology to accurately control growth factor release to promote soft tissue engineering in vivo.