Molecular cloning and functional characterization of human MIP-1 delta, a new C-C chemokine related to mouse CCF-18 and C10

UGRP1-modulated MARCO+ alveolar macrophages contribute to age-related lung fibrosis

The aging lungs are vulnerable to chronic pulmonary diseases; however, the underlying mechanisms are not well understood. In this study, we compared the aging lungs of 20-24-month-old mice with the young of 10-16-week-old mice, and found that aging airway epithelial cells significantly upregulated the expression of uteroglobin-related protein 1 (UGRP1), which was responsible for the higher levels of CCL6 in the aging lungs. Alveolar macrophages (AMs) changed intrinsically with aging, exhibiting a decrease in cell number and altered gene expression. Using terminal differentiation trajectories, a population of MARCO⁺ AMs with the ability to produce CCL6 was identified in the aging lungs. Upregulated UGRP1was demonstrated to modulate CCL6 production of AMs in the UGRP1-MARCO pair in vivo and in vitro. Furthermore, MARCO⁺ AMs aggravated bleomycin-induced pulmonary fibrosis in a CCL6-dependent manner in the aged mice, and blocking MARCO or neutralizing CCL6 significantly inhibited pulmonary fibrosis, similar to the depletion of AMs. The age-related upregulation of UGRP1 and MARCO⁺ AMs, involved in the progression of lung fibrosis, was also observed in human lung tissues. Thus, UGRP1 modulated MARCO⁺ AMs regarding the age-related lung fibrosis in a CCL6-dependent manner, which is key to establishing optimal targeting for the aging population.

Eosinophil-derived chemokine (hCCL15/23, mCCL6) interacts with CCR1 to promote eosinophilic airway inflammation

Eosinophils are terminally differentiated cells derived from hematopoietic stem cells (HSCs) in the bone marrow. Several studies have confirmed the effective roles of eosinophils in asthmatic airway pathogenesis. However, their regulatory functions have not been well elucidated. Here, increased C-C chemokine ligand 6 (CCL6) in asthmatic mice and the human orthologs CCL15 and CCL23 that are highly expressed in asthma patients are described, which are mainly derived from eosinophils. Using Ccl6 knockout mice, further studies revealed CCL6-dependent allergic airway inflammation and committed eosinophilia in the bone marrow following ovalbumin (OVA) challenge and identified a CCL6-CCR1 regulatory axis in hematopoietic stem cells (HSCs). Eosinophil differentiation and airway inflammation were remarkably decreased by the specific CCR1 antagonist BX471. Thus, the study identifies that the CCL6-CCR1 axis is involved in the crosstalk between eosinophils and HSCs during the development of allergic airway inflammation, which also reveals a potential therapeutic strategy for targeting G protein-coupled receptors (GPCRs) for future clinical treatment of asthma.

Is Keratoconus an Inflammatory Disease? The Implication of Inflammatory Pathways

PURPOSE

Keratoconus is considered a non-inflammatory condition. Recently however, increased proinflammatory cytokines have been detected in the tears of keratoconic patients and clinical and immunohistochemical observations reported infiltration of matured dendritic cells and leukocytes. Our laboratory utilized cytokine antibody arrays to elucidate the inflammatory aspects of keratoconus.

METHODS

Protein was extracted from 42 corneal buttons (14 keratoconic and 28 non-keratoconic) and incubated with cytokine antibody arrays scanning 120 cytokines. Mann Whitney U test with a p-value of <0.05 was considered significant.

RESULTS

Pathways for wound healing, neuroprotection, angiogenesis, and inflammation were activated in keratoconic samples with 23 cytokines showing significant elevation. Fifteen were expressed only in keratoconus with 8 cytokines elevated 1.7-42-fold.

CONCLUSION

This study identified elevated inflammatory pathways covering immune responses in keratoconus. Our results support the evidence for inflammatory pathway activation in keratoconus and a possible redefinition of keratoconus as a chronic inflammatory corneal disease.

Relationship between transforming growth factor-β1 and type 2 diabetic nephropathy risk in Chinese population

BACKGROUND

Diabetes mellitus (DM) is divided into four different etiological categories: type 1 DM (T1DM), type 2 DM (T2DM), other specific types, and gestational DM. One severe complication of T2DM is type 2 diabetic nephropathy (T2DN). The possible association of serum transforming growth factor-β1 (TGF-β1) levels and the TGF-β1 T869C gene polymorphism with patient susceptibility to T2DN in Chinese population is unclear at present. This study was conducted to assess these relationships in Chinese population by a meta-analysis.

METHODS

Association reports were searched and pulled from the Cochrane Library, the China Biological Medicine Database (CBM), and PubMed on March 1, 2018, and eligible studies were selected and used for calculations. The results were expressed as weighted mean differences (MD) for continuous data. Odds ratios (OR) were used to express the results for dichotomous data. Additionally, 95% confidence intervals (CI) were calculated.

RESULTS

Forty-eight reports for the relationship between serum TGF-β1 levels and the risk of T2DN and 13 studies on the association of the TGF-β1 T869C gene polymorphism with susceptibility to T2DN in Chinese population were retrieved from this study. Serum TGF-β1 levels in the T2DM group were higher than those in the normal control group (MD = 17.30, 95% CI: 12.69-21.92, P < 0.00001). The serum TGF-β1 level in the T2DN group was significantly higher than that in the normal control group (MD = 70.03, 95% CI: 60.81-79.26, P < 0.00001;). The serum TGF-β1 level in the T2DN group was significantly higher than that in the T2DM group (MD = 56.18, 95% CI: 46.96-65.39, P < 0.00001). Serum TGF-β1 levels in T2DM patients with microalbuminuria were increased when compared with those in T2DM patients with normoalbuminuria. Furthermore, serum TGF-β1 levels in T2DM patients with macroalbuminuria were increased when compared with those in T2DM patients with microalbuminuria. The TGF-β1 T allele, TT allele and CC genotype were associated with T2DN susceptibility in Chinese population (T: OR = 0.74, 95% CI: 0.59-0.92, P = 0.007; TT: OR = 0.55, 95% CI: 0.31-0.96, P = 0.04; CC: OR = 1.38, 95% CI: 1.14-1.67, P = 0.001).

CONCLUSIONS

High levels of TGF-β1 are associated with susceptibility to T2DM, T2DN and the progression of proteinuria in T2DN patients in Chinese population. Further, the TGF-β1 T allele, and TT genotype were protective factors against the onset of T2DN and CC genotype was a risk factor for the susceptibility of T2DN in Chinese populations.

Cytokine Expression of Stem Cells Originating from the Apical Complex and Coronal Pulp of Immature Teeth

INTRODUCTION

The aim of this study was to measure and compare the expression levels of cytokines from developing apical complex cells (DACCs) and dental pulp stem cells (DPSCs) of the immature tooth.

METHODS

DPSC-conditioned medium (CM) and DACCs-CM were obtained from human young teeth, and 174 cytokines secreted from each CM were identified and compared. A cytokine membrane array and enzyme-linked immunosorbent assay were used to measure and compare the expression levels of the cytokines. Immunocytochemistry targeting insulin-like growth factor-1 and neurotrophin-3 was additionally performed.

RESULTS

There were statistically significant differences in the expression levels of 25 cytokines: 22 and 3 were expressed more strongly in DPSCs-CM and DACCs-CM, respectively. Odontoblast differentiation-related cytokines were more strongly expressed in DPSCs-CM, while cell-proliferation-related cytokines were more strongly expressed in DACCs-CM. Proinflammatory and anti-inflammatory cytokines were predominantly expressed in DPSCs-CM and DACCs-CM, respectively.

CONCLUSIONS

DPSCs may exert a stronger paracrine effect than DACCs on regeneration of the dentin-pulp complex, in terms of odontoblast differentiation.

Beta-Chemokine CCL15 Affects the Adhesion and Migration of Hematopoietic Progenitor Cells

BACKGROUND

Hematopoietic stem and progenitor cell (HPC) motility is essential for HPC transplantation. The chemokine CXCL12 is key for HPC motility. Further regulators are of interest to improve HPC transplantation and regenerative medicine. Here the impact of the human chemokine CCL15 on HPC motility was investigated.

METHODS

CCL15 plasma concentrations were determined during HPC mobilization in humans. Activity of CCL15 on HPCs was investigated in murine assays, including chemotaxis, adhesion, and CFU-A assays, and competitive repopulation assays.

RESULTS

During HPC mobilization with granulocyte colony-stimulating factor, blood plasma contains increased concentrations (1.1 ± 0.1 ng/ml) of activated CCL15(27-92) versus 0.4 ± 0.1 ng/ml in controls (p = 0.02). CCL15(27-92) significantly enhanced CXCL12-induced transwell migration of Lin-/Sca1+ HPCs and strengthened shear stress-dependent adhesion to vascular cell adhesion molecule-1 (VCAM-1). CCL15(27-92) dose-dependently reduced the colony size in CFU-A assays performed with murine bone marrow and Lin-/Sca1+ HPCs. CCL15(27-92) did not show a direct impact on cell cycle status of HPCs. In murine repopulation assays, pretreatment of bone marrow with CCL15(27-92) significantly increased competitive repopulation.

CONCLUSION

Our results point to a regulation of HPCs by CCL15 by modulating migratory and adhesive properties of HPCs with the potency to improve HPC short-term engraftment in stem cell transplantation.

Circulating levels of immune and inflammatory markers and long versus short survival in early-stage lung cancer

BACKGROUND

Some patients diagnosed with early-stage lung cancer and treated according to standard care survive for only a short period of time, while others survive for years for reasons that are not well understood. Associations between markers of inflammation and survival from lung cancer have been observed.

MATERIALS AND METHODS

Here, we investigate whether circulating levels of 77 inflammatory markers are associated with long versus short survival in stage I and II lung cancer. Patients who had survived either <79 weeks (~1.5 years) (short survivors, SS) or >156 weeks (3 years) (long survivors, LS) were selected from a retrospective population-based study. Logistic regression was used to calculate adjusted odds ratios (ORs) and corresponding 95% confidence intervals (CIs). The false discovery rate was calculated to adjust for multiple testing.

RESULTS

A total of 157 LS and 84 SS were included in this analysis. Thirteen markers had adjusted OR on the order of 2- to 5-fold when comparing the upper and lower quartiles with regard to the odds of short survival versus long. Chemokine CCL15 [chemokine (C-C motif) ligand 15] was the most significant marker associated with increased odds of short survival (ORs = 4.93; 95% CI 1.90-12.8; q-value: 0.042). Smoking and chronic obstructive pulmonary disease were not associated with marker levels.

CONCLUSIONS

Our results provide some evidence that deregulation of inflammatory responses may play a role in the survival of early-stage lung cancer. These findings will require confirmation in future studies.

Expression and regulation of CCL15 by human airway smooth muscle cells

BACKGROUND

Structural cells are an important reservoir of chemokines that coordinate the influx of various immune cells to the lungs of asthmatics. Airway smooth muscle cells (ASMC) are an important source of these chemokines. CCL15 is a recently described chemo-attractant for neutrophils, eosinophils, monocytes and lymphocytes.

OBJECTIVE

To determine the production and the regulation of CCL15 by ASMC and to investigate its production in asthmatic airways.

METHODS

Human ASMC were obtained from main bronchial airway segments of patients with mild, moderate and severe asthma. To induce chemokine production, cells were incubated with IL-4, IL-13, TNF-α or IFN-γ in presence or absence of dexamethasone, mithramycin A (SP-1 inhibitor) or the IKK-2 inhibitor, AS602868. CCL15 mRNA expression was evaluated by real-time PCR. Immunoreactive CCL15 was detected by immuno-fluorescence and CCL15 protein concentration in the supernatant was measured using ELISA.

RESULTS

CCL15 is constitutively expressed in human ASMC and is strongly up-regulated by TNF-α. This up-regulation is inhibited by dexamethasone, mithramycin A and AS602868. TNF-α-induced CCL15 levels can be synergistically enhanced by the presence of IFN-γ, at both the transcriptional and translation level. This synergism is NF-κB-dependent. Asthmatic biopsies demonstrated higher expression of CCL15 compared with non-asthmatic controls.

CONCLUSION AND CLINICAL RELEVANCE

Our results show that ASMC are a potent source of CCL15 in the airways and may directly participate in the recruitment of inflammatory cells to asthmatic airways. Targeting the production of CCL15 by ASMC might reduce the inflammatory response within the airways of asthmatic patients.

Inactivation of chemokine (C-C motif) receptor 1 (CCR1) suppresses colon cancer liver metastasis by blocking accumulation of immature myeloid cells in a mouse model

Recent reports have suggested critical roles of myeloid cells in tumor invasion and metastasis, although these findings have not led to therapeutics. Using a mouse model for liver dissemination, we show that mouse and human colon cancer cells secrete CC-chemokine ligands CCL9 and CCL15, respectively, and recruit CD34(+) Gr-1(-) immature myeloid cells (iMCs). They express CCL9/15 receptor CCR1 and produce matrix metalloproteinases MMP2 and MMP9. Lack of the Ccr1, Mmp2, or Mmp9 gene in the host dramatically suppresses outgrowths of disseminated tumors in the liver. Importantly, CCR1 antagonist BL5923 blocks the iMC accumulation and metastatic colonization and significantly prolongs the survival of tumor-bearing mice. These results suggest that CCR1 antagonists can provide antimetastatic therapies for patients with disseminated colon cancer in the liver.

A novel role for constitutively expressed epithelial-derived chemokines as antibacterial peptides in the intestinal mucosa

Intestinal-derived chemokines have a central role in orchestrating immune cell influx into the normal and inflamed intestine. Here, we identify the chemokine CCL6 as one of the most abundant chemokines constitutively expressed by both murine small intestinal and colonic epithelial cells. CCL6 protein localized to crypt epithelial cells, was detected in the gut lumen and reached high concentrations at the mucosal surface. Its expression was further enhanced in the small intestine following in vivo administration of LPS or after stimulation of the small intestinal epithelial cell line, mIC(c12), with IFNgamma, IL-4 or TNFalpha. Recombinant- and intestinal-derived CCL6 bound to a subset of the intestinal microflora and displayed antibacterial activity. Finally, the human homologs to CCL6, CCL14 and CCL15 were also constitutively expressed at high levels in human intestinal epithelium, were further enhanced in inflammatory bowel disease and displayed similar antibacterial activity. These findings identify a novel role for constitutively expressed, epithelial-derived chemokines as antimicrobial peptides in the intestinal mucosa.

CC chemokine receptor-1 activates intimal smooth muscle-like cells in graft arterial disease

BACKGROUND

Graft arterial disease (GAD) limits long-term solid-organ allograft survival. The thickened intima in GAD contains smooth muscle-like cells (SMLCs), leukocytes, and extracellular matrix. The intimal SMLCs in mouse GAD lesions differ from medial smooth muscle cells in their function and phenotype. Although intimal SMLCs may originate by migration and modulation of donor medial cells or by recruitment of host-derived precursors, the mechanisms that underlie their localization within grafts and the factors that drive these processes remain unclear.

METHODS AND RESULTS

This study of aortic transplantation in mice demonstrated an important function for chemokines beyond their traditional role in leukocyte recruitment and activation. Intimal SMLCs, but not medial smooth muscle cells, express functional CC chemokine receptor-1 (CCR1) and respond to RANTES by increased migration and proliferation. Although RANTES infusion in vivo promoted inflammatory cell accumulation in the adventitia of aortic allografts of wild-type and CCR1-deficient recipients, it increased GAD intimal thickening with SMLC proliferation in only the wild-type hosts. Aortic allografts transplanted into CCR1-deficient mice after wild-type bone marrow transplantation did not develop intimal lesions, which indicates that CCR1-bearing inflammatory cells do not contribute to intimal lesion formation. Moreover, RANTES induced SMLC proliferation in vitro but did not promote medial smooth muscle cell growth. Blockade of CCR5 attenuated RANTES-induced T-cell and monocyte/macrophage proliferation but did not affect RANTES-induced SMLC proliferation, consistent with a larger role of CCR1-binding chemokines in SMLC migration and proliferation and GAD development.

CONCLUSIONS

These studies provide a novel mechanistic insight into the formation of vascular intimal hyperplasia and suggest a novel therapeutic strategy for preventing allograft arteriopathy.

Receptors for advanced glycation end-products targeting protect against hyperoxia-induced lung injury in mice

Patients with acute lung injury almost always require supplemental oxygen during treatment; however, elevated oxygen itself is toxic. Receptors for advanced glycation end-products (RAGE) are multi-ligand cell surface receptors predominantly localized to alveolar type I cells that influence development and cigarette smoke-induced inflammation, but studies that address the role of RAGE in acute lung injury are insufficient. In the present investigation, we test the hypothesis that RAGE signaling functions in hyperoxia-induced inflammation. RAGE-null mice exposed to hyperoxia survived 3 days longer than age-matched wild-type mice. After 4 days in hyperoxia, RAGE-null mice had less total cell infiltration into the airway, decreased total protein leak, diminished alveolar damage in hematoxylin and eosin-stained lung sections, and a lower lung wet-to-dry weight ratio. An inflammatory cytokine antibody array revealed decreased secretion of several proinflammatory molecules in lavage fluid obtained from RAGE knockout mice when compared with wild-type control animals. Real-time RT-PCR and immunoblotting revealed that hyperoxia induced RAGE expression in primary alveolar epithelial cells, and immunohistochemistry identified increased RAGE expression in the lungs of mice after exposure to hyperoxia. These data reveal that RAGE targeting leads to a diminished hyperoxia-induced pulmonary inflammatory response. Further research into the role of RAGE signaling in the lung should identify novel targets likely to be important in the therapeutic alleviation of lung injury and associated persistent inflammation.

The chemokine CCL6 promotes innate immunity via immune cell activation and recruitment

Septic syndrome is a consequence of innate immune failure. Recent studies showed that the CC chemokine CCL6 enhanced antimicrobial immunity during experimental sepsis through an unknown mechanism. The present study demonstrates that transgenic CCL6 expression abolishes mortality in a septic peritonitis model via the modulation of resident peritoneal cell activation and, more importantly, through the recruitment of IFN-producing NK cells and killer dendritic cells into the peritoneum. Thus, CCL6 attenuates the immune failure during sepsis, in part, through a protective type 1-cytokine mediated mechanism.

Vascular Remodeling in Transplant Vasculopathy

As therapeutic strategies to prevent acute rejection progressively improve, transplant vasculopathy (TV) constitutes the single most important limitation for long-term functioning of solid organ allografts. In TV, allograft arteries characteristically develop severe, diffuse intimal hyperplastic lesions that eventually compromise luminal flow and cause ischemic graft failure. Traditional immunosuppressive strategies that check acute allograft rejection do not prevent TV; indeed 50% of transplant recipients will have significant disease within five years of organ transplantation, and 90% will have significant TV a decade after their surgery. TV can involve the entire length of the transplanted arterial bed, including penetrating intraorgan arterioles. Indeed, the luminal narrowing of such penetrating vessels may be the most functionally significant because arterioles represent the major contributors to tissue vascular resistance. Because of the diffuseness of TV involvement in the allograft vascular bed, the only currently definitive therapy requires re-transplantation. Nevertheless, as we better understand the pathogenesis and critical mediators of these lesions, pharmacological advances can be anticipated. Other articles in this thematic review series focus on the specifics of the inciting injury, the cytokines and chemokines that drive TV development, and the nature of the recruited cells in TV lesions, as well as the pathogenic similarities between TV and other vascular lesions such as atherosclerosis. This review focuses on the mechanisms of vascular wall remodeling in TV, including the intimal accumulation of smooth muscle-like cells and associated extracellular matrix, medial smooth muscle cell degeneration, and adventitial fibrosis. A brief overview highlights the aneurysmal changes that can accrue when vessel wall inflammation has a cytokine profile distinct from the typical proinflammatory interferon-gamma-dominated milieu.

Patterns of protein expression in infectious meningitis: a cerebrospinal fluid protein array analysis

Seventy-nine cytokines, chemokines, and growth factors were measured by protein array analysis in the cerebrospinal fluid of patients with meningitis and controls. Several factors were found to be regulated, which have not been studied in the CNS before, e.g., macrophage inflammatory protein-1delta (CCL15) and neutrophil-activating peptide-2 (CXCL7). In pneumococcal meningitis, other new observations were an increase of macrophage migration inhibitory factor, monocyte chemoattractant protein-2 (CCL8), pulmonary and activation-regulated chemokine (CCL18), and macrophage inflammatory protein-3alpha (CCL20), and a sustained upregulation of several growth factors. In viral meningitis, new findings were an elevation of CCL8, thrombopoietin, and vascular endothelial growth factor.

Proteolytic activation of alternative CCR1 ligands in inflammation

Although chemokines CCL3/MIP-1alpha and CCL5/RANTES are considered to be primary CCR1 ligands in inflammatory responses, alternative CCR1 ligands have also been described. Indeed, four such chemokines, CCL6/C10/MIP-related protein-1, CCL9/MIP-1gamma/MIP-related protein-2, CCL15/MIP-1delta/hemofiltrate CC chemokine-2/leukotactin-1, and CCL23/CKbeta8/myeloid progenitor inhibitory factor-1, are unique in possessing a separately encoded N-terminal domain of 16-20 residues and two additional precisely positioned cysteines that form a third disulfide bridge. In vitro, these four chemokines are weak CCR1 agonists, but potency can be increased up to 1000-fold by engineered or expression-associated N-terminal truncations. We examined the ability of proinflammatory proteases, human cell supernatants, or physiological fluids to perform N-terminal truncations of these chemokines and thereby activate their functions. Remarkably, most of the proteases and fluids removed the N-terminal domains from all four chemokines, but were relatively unable to cleave the truncated forms further. The truncated chemokines exhibited up to 1000-fold increases in CCR1-mediated signaling and chemotaxis assays in vitro. In addition, N-terminally truncated CCL15/MIP-1delta and CCL23/CKbeta8, but not CCL3/MIP-1alpha or CCL5/RANTES, were detected at relatively high levels in synovial fluids from rheumatoid arthritis patients. These data suggest that alternative CCR1 ligands are converted into potent chemoattractants by proteases released during inflammatory responses in vivo.

Cytokine gene expression profiles in kidney medulla and cortex of obese hypertensive dogs

BACKGROUND

The molecular mechanisms linking abnormal kidney function and obesity hypertension are poorly understood. This study compared gene expression profiles in the kidney medulla and cortex of obese and lean dogs.

METHODS

Lean dogs (N= 4) were fed a standard kennel ration and obese dogs (N= 4) were fed the standard diet plus 0.5 to 0.9 kg of cooked beef fat per day for 10 weeks. The dogs were instrumented for continuous monitoring of mean arterial pressure (MAP), heart rate, glomerular filtration rate (GFR), and effective renal plasma flow (RPF). The relative mRNA levels of 375 genes in renal cortex and medulla were determined simultaneously using cDNA membrane arrays (R&D Systems).

RESULTS

The high fat diet increased body weight by 57% and MAP increased by 24 mm Hg (112 +/- 1 mm Hg vs. 88 +/- 3 mm Hg) in obese compared to lean dogs. In obese dogs, expression of 11 and 13 genes changed significantly (N= 4; P < 0.05) in the renal medulla and the cortex, respectively, relative to the lean dogs. Differences in renal gene expression profiles between lean and obese dogs were closely related to functional pathways, including those associated with sympathetic activation, inflammatory response, matrix formation, angiogenesis, endothelial dysfunction, attenuated actions of leptin, and attenuated cell survival.

CONCLUSION

A high fat diet in dogs is associated with marked changes in renal gene expression profiles that provide potential molecular links to pathways associated with altered renal function and structure in obesity hypertension.

Functional analysis of chemically synthesized derivatives of the human CC chemokine CCL15/HCC-2, a high affinity CCR1 ligand

The CCL15 is a human CC chemokine that activates the receptors, CCR1 and CCR3. Unlike other chemokines, it contains an unusually long N-terminal domain of 31 amino acids preceding the first cysteine residue and a third disulfide bond. To elucidate the functional role of distinct structural determinants, a series of sequential amino-terminal truncated and point-mutated CCL15 derivatives as well as mutants lacking the third disulfide bond and the carboxy-terminal alpha-helix were synthesized using 9-fluorenylmethoxycarbonyl (Fmoc) chemistry. We demonstrate that a truncation of 24 amino acid residues (delta24-CCL15) converts the slightly active 92-residue delta0-CCL15 into a potent agonist of CC chemokine receptor 1 (CCR1) and a weak agonist of CCR3 in cell-based assays. The biological activity decreases from delta24-CCL15 to delta29-CCL15, and re-increases from delta29-CCL15 to delta30-CCL15. Thus, an exocyclic N-terminal region of only one amino acid residue is sufficient for efficient CCR1 activation. As none of the peptides investigated except for delta24-CCL15 activates CCR3, we suggest that CCR1 is the major receptor for CCL15 in vivo. Further we demonstrate that the third disulfide bond of CCL15 and an exchange of tyrosine in position 70 by a leucine residue, which is conserved in CXC chemokines, do not alter the interaction with CCR1. In contrast, a CCL15 derivative lacking the carboxy-terminal alpha-helix exhibits a complete loss of tertiary structure and hence loss of CCR1 agonistic and binding activity. This study demonstrates that specific protein residues in chemokines, which contribute to receptor-ligand interaction, vary significantly between chemokines and cannot be extrapolated using data from functionally related chemokines.

The C10/CCL6 chemokine and CCR1 play critical roles in the pathogenesis of IL-13-induced inflammation and remodeling

IL-13 is a potent stimulator of inflammation and tissue remodeling that plays a key role in the pathogenesis of a wide variety of human disorders. To further understand these responses, studies were undertaken to define the role(s) of the chemokine C10/CCL6 in the pathogenesis of IL-13-induced alterations in the murine lung. IL-13 was a very potent stimulator of C10/CCL6 mRNA and protein, and IL-13-induced inflammation, alveolar remodeling, and compliance alterations were markedly ameliorated after C10/CCL6 neutralization. Treatment with anti-C10/CCL6 decreased the levels of mRNA encoding matrix metalloproteinase-2 (MMP-2), MMP-9, and tissue inhibitor of metalloproteinase-4 (TIMP-4) in lungs from wild-type mice. C10/CCL6 neutralization also decreased the ability of IL-13 to stimulate the production of monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha, MMP-2, MMP-9, and cathepsins-K, -L, and -S and the ability of IL-13 to inhibit alpha1-antitrypsin. In accord with these findings, a targeted null mutation of CCR1, a putative C10/CCL6 receptor, also decreased IL-13-induced inflammation and alveolar remodeling and caused alterations in chemokines, proteases, and antiproteases comparable to those seen after C10/CCL6 neutralization. These C10/CCL6 and CCR1 manipulations did not alter the production of transgenic IL-13. These studies demonstrate that IL-13 is a potent stimulator of C10/CCL6 and highlight the importance of C10/CCL6 and signaling via CCR1 in the pathogenesis of the IL-13-induced pulmonary phenotype. They also describe a C10/CCL6 target gene cascade in which C10/CCL6 induction is required for optimal IL-13 stimulation of selected chemokines (monocyte chemoattractant protein-1 and MIP-1alpha) and proteases (MMP-2, MMP-9, and cathepsins-K, -L, and -S) and the inhibition of alpha1-antitrypsin.

Differential chemokine activation of CC chemokine receptor 1-regulated pathways: ligand selective activation of Gα 14-coupled pathways

Chemokines regulate the chemotaxis, development, and differentiation of many cell types enabling the regulation of routine immunosurveillance and immunological adaptation. CC chemokine receptor 1 (CCR1) is the target of 11 chemokines. This promiscuity of receptor-ligand interactions and the potential for functional redundancy has led us to investigate the selective activation of CCR1-coupled pathways by known CCR1 agonists. Chemokines leukotactin-1, macrophage inflammatory protein (MIP)-1alpha, monocyte chemotactic peptide (MCP)-3, RANTES, and MIP-1delta all inhibited adenylyl cyclase activity in cells transiently transfected with CCR1. In contrast, only MIP-1delta was unable to signal via G14-, G16- or chimeric 16z44-coupled pathways. In a stable cell line expressing CCR1 and Galpha14, all of these five chemokines along with hemofiltrate CC chemokine (HCC)-1 and myeloid progenitor inhibitory factor (MPIF)-1 were able to stimulate G(i/o)-coupled pathways, but MIP-1delta, HCC-1 and MPIF-1 were unable to activate G14-mediated stimulation of phospholipase Cbeta activity. In addition, MIP-1delta was unable to promote the phosphorylation of extracellular signal-regulated kinase and c-Jun N-terminal kinase. This suggests that different chemokines are able to selectively activate CCR1-coupled pathways, probably because of different intrinsic ligand efficacies. CCR1 and Galpha14 or Galpha16 are co-expressed in several cell types and we hypothesize that selective activation of chemokine receptors provides a mechanism by which chemokines are able to fine-tune intracellular signaling pathways.

Interaction of IL-13 and C10 in the pathogenesis of bleomycin-induced pulmonary fibrosis

The initial stimulus for inflammatory cell recruitment and the mechanisms responsible for the perpetuation and evolution of chronic inflammation, granulation tissue formation, and fibrosis have not been fully elucidated. Although interleukin (IL)-13, a Th2 cytokine, has been shown to have direct effects on fibroblasts that support fibroproliferation, it is also a potent inducer of a novel CC chemokine, C10, which is chemotactic for mononuclear phagocytes. The macrophage/mononuclear phagocyte has been shown to have a role in the pathogenesis of pulmonary fibrosis, serving as an important source of growth factors that regulate extracellular matrix synthesis. In this study we demonstrate that IL-13 and C10 are elevated in the pathogenesis of bleomycin-induced pulmonary fibrosis. Neutralization of IL-13, but not IL-4, attenuated bleomycin-induced pulmonary fibrosis and levels of C10, suggesting that IL-13 has an important role in the development of pulmonary fibrosis. IL-13 is a potent inducer of C10 in vivo, and neutralization of C10 attenuated bleomycin-induced pulmonary fibrosis and intrapulmonary macrophage numbers. This suggests that IL-13 has a role in the development of pulmonary fibrosis that is independent of its direct effect on fibroblasts and is evidence for an interaction between Th2 cytokines and specific CC chemokines.

Eotaxin/CCL11 is involved in acute, but not chronic, allergic airway responses to Aspergillus fumigatus

Eotaxin/CCL11 is a major chemoattractant for eosinophils and Th2 cells. As such, it represents an attractive target in the treatment of allergic disease. The present study addresses the role of eotaxin/CCL11 during acute and chronic allergic airway responses to the fungus Aspergillus fumigatus. Mice lacking the eotaxin gene (Eo-/-) and wild-type mice (Eo+/+) were sensitized to A. fumigatus and received either an intratracheal challenge with soluble A. fumigatus antigens (acute model) or an intratracheal challenge with live A. fumigatus spores or conidia (chronic model). Airway hyperresponsiveness and eosinophil, but not T cell, recruitment were significantly decreased at 24 h after the soluble allergen in A. fumigatus-sensitized Eo-/- mice compared with similarly sensitized Eo+/+ mice. In contrast, the development of chronic allergic airway disease due to A. fumigatus conidia was not altered by the lack of eotaxin. Together, these data suggest that eotaxin initiates allergic airway disease due to A. fumigatus, but this chemokine did not appear to contribute to the maintenance of A. fumigatus-induced allergic airway disease.

Radiation-induced pulmonary fibrosis: examination of chemokine and chemokine receptor families

Fibrosis is a common outcome of chronic inflammation or injury. Pulmonary fibrosis may be the result of abnormal repair after an acute inflammatory response. The process of repair initiated by a tissue insult is largely a function of the activation of cells to produce important biological mediators such as cytokines, growth factors and chemokines, which orchestrate most aspects of the inflammatory response. Consequently, altered regulation of the production of inflammatory cell cytokines and chemokines after injury and repair likely contributes to the fibrosis. Our hypothesis is that chronic expression of specific chemokine and chemokine receptors during the fibrotic phase induced by thoracic irradiation may perpetuate the recruitment and activation of lymphocytes and macrophages, which may contribute to the development of fibrosis. Fibrosis-sensitive (C57BL/6) and fibrosis-resistant (C3H/HeJ) mice were irradiated with a single dose of 12.5 Gy to the thorax. Total lung RNA was prepared and hybridized using microarray analysis and RNase protection assays. At 26 weeks postirradiation, messages encoding the chemokines BLC (now known as Scyb13), C10 (now known as Scya6), IP-10 (now known as Scyb10), MCP-1 (now known as Scya2), MCP-3 (now known as Scya7), MIP-1gamma (now known as Scya9), and RANTES (now known as Scya5) and the chemokine receptors Ccr1, Ccr2, Ccr5 and Ccr6 were elevated in fibrosis-sensitive (C57BL/6) mice. In contrast, only the messages encoding SDF-1alpha (now known as Sdf1) and Ccr1 were elevated 26 weeks postirradiation in fibrosis-resistant (C3H/HeJ) mice. Our results point to the CC and CCR family members as the predominant chemokine responders during the development of fibrosis. These studies suggest that monocyte/macrophage and lymphocyte recruitment and activation are key components of radiation-induced fibrosis.

Requirement of macrophages and eosinophils and their cytokines/chemokines for mammary gland development

Epithelial/mesenchymal cell interactions are necessary for proper ductal morphogenesis throughout all stages of mammary gland development. Besides the well-established stromal components, such as adipocytes and fibroblasts, the mammary stroma is also infiltrated with migrating blood cells, mostly macrophages and eosinophils. The focus of this review is on the role of macrophages and their growth factor colony-stimulating factor 1 (CSF-1) in promoting branching morphogenesis during postnatal mammary gland development through to lactation. The more restricted role of eosinophils and their chemoattractant eotaxin during pubertal ductal morphogenesis is also discussed. A possible interaction between macrophages and eosinophils in ductal morphogenesis is considered, along with the roles of other chemokines. This role of macrophages in normal development also appears to be subverted by tumors of the mammary gland to promote the escape of the tumor cells from the local environment and enhance their rate of metastasis. These data emphasize the dual role of macrophages in the promotion of epithelial growth in normal and cancer states.

Chemokine C10 promotes disease resolution and survival in an experimental model of bacterial sepsis

Previous studies have suggested that the C-C chemokine C10 is involved in the chronic stages of host defense reactions. The present study addressed the role of C10 in a murine model of septic peritonitis, induced by cecal ligation and puncture (CLP). Unlike other C-C chemokines, C10 levels in the peritoneal wash were increased approximately 30-fold above baseline levels at 48 h after CLP surgery. Immunoneutralization of peritoneal C10 levels with polyclonal anti-C10 antiserum during CLP-induced peritonitis negatively impacted mouse survival over 4 days. In contrast, when 500 ng of recombinant murine C10 was administered immediately after CLP surgery, the 4-day survival rate increased from 20% to over 60%. The C10 therapy appeared to facilitate a rapid and significant enhancement of the levels of tumor necrosis factor alpha (TNF-alpha) and monocyte chemoattractant protein-1 (MCP-1) and a later increase in interleukin-13 (IL-13) levels in the peritoneal cavity. In vitro studies showed that the combination of IL-1beta and C10 markedly augmented TNF-alpha synthesis by peritoneal macrophages and that C10 synthesis was induced in these cells following their exposure to IL-13. At 24 h after CLP surgery, only 25% of C10-treated mice were bacteremic versus 85% of the control group that exhibited dissemination of bacteria into the circulation. The lack of bacteremia in C10-treated mice appeared to be related, in part, to in vitro evidence that C10 significantly enhanced the bacterial phagocytic activity of peritoneal macrophages. In addition, in vivo evidence suggested that C10 therapy significantly reduced the amount of material that leaked from the damaged gut. Taken together, the results of this study demonstrate that the C10 chemokine rapidly promotes disease resolution in the CLP model through its direct effects on the cellular events critically involved in host defense during septic peritonitis.

Novel chicken CXC and CC chemokines

Upon stimulation with lipopolysaccharide (LPS) the chicken macrophage cell line HD-11 secretes factors with cytokine activity. To characterize these molecules, representational difference analysis with RNA of LPS-induced and uninduced HD-11 cells was performed. Two cDNA clones were isolated that code for polypeptides with structural features of chemokines. cDNA K60 codes for a novel CXC chemokine of 104 residues including a putative signal peptide of 20 amino acids at the N-terminus. It is 67% identical to the previously cloned chicken chemokine 9E3/CEF4. K60 exhibits a similar degree of sequence identity to human interleukin 8 and other related CXC chemokines (about 50%), rendering straight-forward predictions of its biological properties difficult. cDNA K203 codes for a novel CC chemokine of 89 amino acids including a putative N-terminal signal peptide of 21 residues. It is 43% identical to a previously characterized chicken protein with homology to mammalian macrophage inflammatory protein 1beta (MIP-1beta). K203 exhibits about 50% sequence identity to human MIP-1beta and other related CC chemokines.

Synthesis and characterization of the human CC chemokine HCC-2

Human CC chemokine 2 (HCC-2) is a novel member of the chemokine peptide family that induces chemotaxis of monocytes, T lymphocytes and eosinophils via activation of the CCR-1 and CCR-3 receptors. Fmoc chemistry was optimized and used to synthesize the biologically active 66-residue peptide HCC-2-(48-113). Introduction of the three disulfide bonds was achieved by oxidative folding in the presence of the redox system cysteine/cystine. Alternatively, a semiselective approach utilizing a mixed Acm/Trt protection scheme for disulfide formation was applied. It was found that, without participation of the two HCC-2-specific cysteine residues in positions 64 and 104, the two typical chemokine disulfides are formed predominantly during oxidative folding. In addition, the mutant [Ala64,104]HCC-2-(48-113) lacking the third disulfide bond that discriminates HCC-2 from most other chemokines was synthesized. For disulfide bond formation, oxidative folding was compared with the use of Acm/Trt protection. HCC-2-(48-113) and the mutant [Ala64,104]HCC-2-(48-113) were further analyzed by CD and one-dimensional 1H NMR-spectroscopy. Both peptides adopt a similar stable secondary and tertiary structure in solution.

Chemokines and atherosclerosis

Chemokines or chemotactic cytokines represent an expanding family of structurally related small molecular weight proteins, recognised as being responsible for leukocyte trafficking and activation. Soon after the discovery of this class of cytokines, about a decade ago, monocyte chemoattractant protein-1 (MCP-1) was found to be highly expressed in human atherosclerotic lesions and postulated to be central in monocyte recruitment into the arterial wall and developing lesions. In this review, we will discuss our present knowledge about MCP-1 and its receptor CCR2 and their role in atherogenesis. Although less well established, other chemokines such as RANTES, MIP-1alpha and MIP-1beta have also been implicated in atherosclerotic lesion formation as are a number of more recently discovered chemokines like MCP-4, ELC and PARC. The role of these chemokines in the progression of atherosclerosis will be discussed as well as the emerging role of IL-8, mostly know for its effects on neutrophils. Particular attention will be given not only to the involvement of chemokines in the inflammatory recruitment of monocytes/macrophages, but also to their role in the related local immune responses and vascular remodelling which occur during the formation of unstable atherosclerotic plaques.

Peptide T blocks GP120/CCR5 chemokine receptor-mediated chemotaxis

We previously reported that certain short gp120 V2 region peptides homologous to vasaoactive intestinal peptide (VIP), such as "peptide T," were potent inhibitors of gp120 binding, infectivity, and neurotoxicity. The present study shows that synthetic V2-region-derived peptides have potent intrinsic chemotaxis agonist activity for human monocytes and also act as antagonists of high-affinity (0.1 pM) gp120-mediated monocyte chemotaxis. Selectivity is shown in that peptide T is more potent at suppressing M-tropic than T-tropic gp120 chemotaxis. Peptide T was also able to suppress monocyte chemotaxis to MIP-1beta, a chemokine with selectivity for CCR5 chemokine receptors, while chemotaxis of the more promiscuous ligand RANTES was not inhibited, nor was chemotaxis mediated by SDF-1alpha. In order to determine if peptide T mediated its gp120 antagonistic effects via modulation of CCR5 receptors, RANTES chemotaxis was studied using a CCR5 receptor-transfected HOS cell line. In this case, RANTES chemotaxis was potently inhibited by V2-region-derived short peptides. Peptide T also partially suppressed (125)I-MIP1-beta binding to human monocytes, suggesting action at a subset of MIP1-beta receptors. The V2 region of gp120 thus contains a potent receptor binding domain and synthetic peptides derived from this region modulate CCR5 chemokine receptor chemotactic signaling caused by either gp120 or chemokine ligands. The results have therapeutic implications and may explain recent clinical improvements, in that HIV/gp120 actions at CCR5 receptors, such as occur in the brain or early infection, would be susceptible to peptide T inhibition.

Immunomodulatory Role of C10 Chemokine in a Murine Model of Allergic Bronchopulmonary Aspergillosis

The immunomodulatory role of the chemokine C10 was explored in allergic airway responses during experimental allergic bronchopulmonary aspergillosis (ABPA). The intratracheal delivery of Asperigillus fumigatus Ag into A. fumigatus-sensitized mice resulted in significantly increased levels of C10 within the bronchoalveolar lavage, and these levels peaked at 48 h after A. fumigatus challenge. In addition, C10 levels in BAL samples were greater than 5-fold higher than levels of other chemokines such as monocyte-chemoattractant protein-1, eotaxin, and macrophage-inflammatory protein-1α. From in vitro studies, it was evident that major pulmonary sources of C10 may have included alveolar macrophages, lung fibroblasts, and vascular smooth muscle cells. Experimental ABPA was associated with severe peribronchial eosinophilia, bronchial hyperresponsiveness, and augmented IL-13 and IgE levels. The immunoneutralization of C10 with polyclonal anti-C10 antiserum 2 h before the intratracheal A. fumigatus challenge significantly reduced the airway inflammation and hyperresponsiveness in this model of ABPA, but had no effect on IL-10 nor IgE levels. Taken together, these data suggest that C10 has a unique role in the progression of experimental ABPA.

Organization of the chemokine gene cluster on human chromosome 17q11.2 containing the genes for CC chemokine MPIF-1, HCC-2, HCC-1, LEC, and RANTES

To understand the organization of the human CC chemokine gene cluster on chromosome 17q11.2, we determined the nucleotide sequence of a region 181 kb long containing five CC chemokine genes, MPIF-1 (SCYA23), HCC-2 (SCYA15), HCC-1 (SCYA14), LEC (SCYA16), and RANTES (SCYA5), by the random shot-gun method. The four CC chemokine genes, MPIF-1, HCC-2, HCC-1, and LEC, are clustered within a region 40 kb long, whereas the RANTES gene is located approximately 10 kb apart from the four chemokine gene minicluster. These chemokine genes are arranged in the same orientation, and their sizes are relatively long, 3.1 (HCC-1)-8.8 kb (RANTES) when compared with other CC chemokine genes, such as MIP-1alpha/LD78alpha (SCYA3) (1.9 kb) and MCP-1 (SCYA2) (1.5 kb). In contrast to most other human CC chemokine genes that consist of three exons, the MPIF-1 and HCC-2 genes, separated by 12 kb, have four exons. When the nucleotide sequences of the MPIF-1 and HCC-2 genes are compared, they are well conserved, including introns and flanking sequences, except for the middle region of the long first intron, indicating that they have been generated recently in evolutionary terms by duplication. In addition to the CC chemokine genes, more than 30 exons are identified in the sequenced region by similarity search against expressed sequence tags (ESTs) and also by the gene prediction program GenScan. This indicates that the chemokine cluster sequenced in this study is a gene-rich region in the human genome.