Regulatory T-cell Depletion Alters the Tumor Microenvironment and Accelerates Pancreatic Carcinogenesis

Regulatory T cells (Treg) are abundant in human and mouse pancreatic cancer. To understand the contribution to the immunosuppressive microenvironment, we depleted Tregs in a mouse model of pancreatic cancer. Contrary to our expectations, Treg depletion failed to relieve immunosuppression and led to accelerated tumor progression. We show that Tregs are a key source of TGFβ ligands and, accordingly, their depletion reprogramed the fibroblast population, with loss of tumor-restraining, smooth muscle actin-expressing fibroblasts. Conversely, we observed an increase in chemokines Ccl3, Ccl6, and Ccl8 leading to increased myeloid cell recruitment, restoration of immune suppression, and promotion of carcinogenesis, an effect that was inhibited by blockade of the common CCL3/6/8 receptor CCR1. Further, Treg depletion unleashed pathologic CD4+ T-cell responses. Our data point to new mechanisms regulating fibroblast differentiation in pancreatic cancer and support the notion that fibroblasts are a heterogeneous population with different and opposing functions in pancreatic carcinogenesis. SIGNIFICANCE: Here, we describe an unexpected cross-talk between Tregs and fibroblasts in pancreatic cancer. Treg depletion resulted in differentiation of inflammatory fibroblast subsets, in turn driving infiltration of myeloid cells through CCR1, thus uncovering a potentially new therapeutic approach to relieve immunosuppression in pancreatic cancer.See related commentary by Aykut et al., p. 345.This article is highlighted in the In This Issue feature, p. 327.

Subcutaneous and visceral adipose tissue gene expression of serum adipokines that predict type 2 diabetes

Type 2 diabetes mellitus (T2D) is predicted by central obesity and circulating adipokines regulating inflammation. We hypothesized that visceral adipose tissue (VAT) in T2D expresses greater levels of proinflammatory molecules. Paired samples of subcutaneous (SAT) and VAT were excised at elective surgery (n = 16, 6 with T2D, n = 8 age- and gender- matched controls). Metabolic parameters were measured in the fasted state: body composition by dual-energy X-ray absorptiometry and insulin action by hyperinsulinemic-euglycemic clamp. Adipose tissue mRNA gene expression was measured by quantitative reverse transcriptase-PCR. Subjects with T2D had higher VAT expression of molecules regulating inflammation (tumor necrosis factor-alpha (TNFalpha), macrophage inflammatory protein (MIP), interleukin-8 (IL-8)). Fasting glucose related to VAT expression of TNFalpha, MIP, serum amyloid A (SAA), IL-1alpha, IL-1beta, IL-8, and IL-8 receptor. Abdominal fat mass was related to VAT expression of MIP, SAA, cAMP response element-binding protein (CREBP), IL-1beta, and IL-8. Insulin action related inversely to VAT complement C3 expression only. There were depot-specific differences in expression of serum T2D predictors: VAT expressed higher levels of complement C3; SAT expressed higher levels of retinol-binding protein-4 (RBP4), adiponectin, and leptin. In summary, VAT in T2D expresses higher levels of adipokines involved in inflammation. VAT expression of these molecules is related to fasting glucose and insulin action. Increased production of these proinflammatory molecules by VAT may explain the links observed between visceral obesity, insulin resistance, and diabetes risk.

The IL-23/Th17 axis contributes to renal injury in experimental glomerulonephritis

T cells infiltrate the kidney in both human and experimental glomerulonephritis, and several lines of evidence indicate that T cell-mediated tissue damage plays an important role in the immunopathogenesis of renal inflammatory diseases. However, the functions of the different T cell subsets, particularly the recently identified interleukin-17 (IL-17)-producing T cells (Th17 cells), are incompletely understood in glomerulonephritis. Here, we identified renal IL-17-producing T cells in the T cell-mediated model of nephrotoxic nephritis in mice. In vitro, IL-17 enhanced the production of the proinflammatory chemokines CCL2/MCP-1, CCL3/MIP-1alpha, and CCL20/LARC, which are implicated in the recruitment of T cells and monocytes, in mouse mesangial cells. To determine the function of Th17 cells in renal inflammation, we induced nephrotoxic nephritis in IL-23 p19(-/-) mice, which have reduced numbers of Th17 cells, and in IL-17(-/-) mice, which are deficient in the effector cytokine IL-17 itself. In comparison with nephritic wild-type mice, IL-23 p19(-/-) mice demonstrated less infiltration of Th17 cells, and both IL-23 p19(-/-) and IL-17(-/-) mice developed less severe nephritis as measured by renal function, albuminuria, and frequency of glomerular crescent formation. These results demonstrate that the IL-23/IL-17 pathway significantly contributes to renal tissue injury in experimental glomerulonephritis. Targeting the IL-23/Th17 axis may be a promising therapeutic strategy for the treatment of proliferative and crescentic glomerulonephritis.

S100B protein stimulates microglia migration via RAGE-dependent up-regulation of chemokine expression and release

The Ca(2+)-binding protein of the EF-hand type, S100B, is abundantly expressed in and secreted by astrocytes, and release of S100B from damaged astrocytes occurs during the course of acute and chronic brain disorders. Thus, the concept has emerged that S100B might act an unconventional cytokine or a damage-associated molecular pattern protein playing a role in the pathophysiology of neurodegenerative disorders and inflammatory brain diseases. S100B proinflammatory effects require relatively high concentrations of the protein, whereas at physiological concentrations S100B exerts trophic effects on neurons. Most if not all of the extracellular (trophic and toxic) effects of S100B in the brain are mediated by the engagement of RAGE (receptor for advanced glycation end products). We show here that high S100B stimulates murine microglia migration in Boyden chambers via RAGE-dependent activation of Src kinase, Ras, PI3K, MEK/ERK1/2, RhoA/ROCK, Rac1/JNK/AP-1, Rac1/NF-κB, and, to a lesser extent, p38 MAPK. Recruitment of the adaptor protein, diaphanous-1, a member of the formin protein family, is also required for S100B/RAGE-induced migration of microglia. The S100B/RAGE-dependent activation of diaphanous-1/Rac1/JNK/AP-1, Ras/Rac1/NF-κB and Src/Ras/PI3K/RhoA/diaphanous-1 results in the up-regulation of expression of the chemokines, CCL3, CCL5, and CXCL12, whose release and activity are required for S100B to stimulate microglia migration. Lastly, RAGE engagement by S100B in microglia results in up-regulation of the chemokine receptors, CCR1 and CCR5. These results suggests that S100B might participate in the pathophysiology of brain inflammatory disorders via RAGE-dependent regulation of several inflammation-related events including activation and migration of microglia.

Microglial translational profiling reveals a convergent APOE pathway from aging, amyloid, and tau

Alzheimer's disease (AD) is an age-associated neurodegenerative disease characterized by amyloidosis, tauopathy, and activation of microglia, the brain resident innate immune cells. We show that a RiboTag translational profiling approach can bypass biases due to cellular enrichment/cell sorting. Using this approach in models of amyloidosis, tauopathy, and aging, we revealed a common set of alterations and identified a central APOE-driven network that converged on CCL3 and CCL4 across all conditions. Notably, aged females demonstrated a significant exacerbation of many of these shared transcripts in this APOE network, revealing a potential mechanism for increased AD susceptibility in females. This study has broad implications for microglial transcriptomic approaches and provides new insights into microglial pathways associated with different pathological aspects of aging and AD.

The mouse mammary carcinoma 4T1: characterization of the cellular landscape of primary tumours and metastatic tumour foci

The murine mammary carcinoma 4T1 causes a leukemoid reaction with profound granulocytosis coincident with the production of tumour-derived growth factors. Here, we study the evolving cellular landscape of primary tumours and metastatic tumour foci and correlate haematopoietic cell infiltration with the production of tumour-derived chemokines. Flow cytometric analysis of enzyme digested primary tumours at different times after transplantation revealed a progressively increasing CD45(+) haematopoietic cell infiltrate consisting predominantly of CD11b(+) myeloid cells. Most of these cells had an F4/80(+)/CD11c(+) phenotype, many of which also stained Gr-1(+). Smaller numbers of Gr-1(+)CD11b(+) granulocytes and lymphoid cells were also identified. Progressive increases in Gr-1(+) granulocytes were observed in enzymatic digests of livers and lungs with metastatic tumour foci. Cultured 4T1 tumour cells expressed mRNA transcripts for the myeloid cell chemokines RANTES, MCP-1 and KC, and enzymatically digested cells from primary 4T1 tumours partially depleted of CD45(+) cells expressed transcripts for these chemokines and also MIP-1alpha and MIP-1beta. These data demonstrate that 4T1 tumour-bearing mice have mixed myeloid cell infiltrates of primary tumours and granulocytic infiltrates of metastatic organs. This pathologic presentation correlated with the expression of tumour-derived chemokines.

Polymerization of MIP-1 chemokine (CCL3 and CCL4) and clearance of MIP-1 by insulin-degrading enzyme

Macrophage inflammatory protein-1 (MIP-1), MIP-1α (CCL3) and MIP-1β (CCL4) are chemokines crucial for immune responses towards infection and inflammation. Both MIP-1α and MIP-1β form high-molecular-weight aggregates. Our crystal structures reveal that MIP-1 aggregation is a polymerization process and human MIP-1α and MIP-1β form rod-shaped, double-helical polymers. Biophysical analyses and mathematical modelling show that MIP-1 reversibly forms a polydisperse distribution of rod-shaped polymers in solution. Polymerization buries receptor-binding sites of MIP-1α, thus depolymerization mutations enhance MIP-1α to arrest monocytes onto activated human endothelium. However, same depolymerization mutations render MIP-1α ineffective in mouse peritoneal cell recruitment. Mathematical modelling reveals that, for a long-range chemotaxis of MIP-1, polymerization could protect MIP-1 from proteases that selectively degrade monomeric MIP-1. Insulin-degrading enzyme (IDE) is identified as such a protease and decreased expression of IDE leads to elevated MIP-1 levels in microglial cells. Our structural and proteomic studies offer a molecular basis for selective degradation of MIP-1. The regulated MIP-1 polymerization and selective inactivation of MIP-1 monomers by IDE could aid in controlling the MIP-1 chemotactic gradient for immune surveillance.

CCL3-CCR5 axis regulates intratumoral accumulation of leukocytes and fibroblasts and promotes angiogenesis in murine lung metastasis process

Metastasis proceeds through interaction between cancer cells and resident cells such as leukocytes and fibroblasts. An i.v. injection of a mouse renal cell carcinoma, Renca, into wild-type mice resulted in multiple metastasis foci in lungs and was associated with intratumoral accumulation of macrophages, granulocytes, and fibroblasts. A chemokine, CCL3, was detected in infiltrating cells and, to a lesser degree, tumor cells, together with an infiltration of leukocytes expressing CCR5, a specific receptor for CCL3. A deficiency of the CCL3 or CCR5 gene markedly reduced the number of metastasis foci in the lung, and the analysis using bone marrow chimeric mice revealed that both bone marrow- and non-bone marrow-derived cells contributed to metastasis formation. CCL3- and CCR5-deficient mice exhibited a reduction in intratumoral accumulation of macrophages, granulocytes, and fibroblasts. Moreover, intratumoral neovascularization, an indispensable process for metastasis, was attenuated in these gene-deficient mice. Intrapulmonary expression of matrix metalloproteinase (MMP)-9 and hepatocyte growth factor (HGF) was enhanced in wild-type mice, and the increases were markedly diminished in CCL3- and CCR5-deficient mice. Furthermore, MMP-9 protein was detected in macrophages and granulocytes, the cells that also express CCR5 and in vitro stimulation by CCL3-induced macrophages to express MMP-9. Intratumoral fibroblasts expressed CCR5 and HGF protein. In vitro CCL3 stimulated fibroblasts to express HGF. Collectively, the CCL3-CCR5 axis appears to regulate intratumoral trafficking of leukocytes and fibroblasts, as well as MMP-9 and HGF expression, and as a consequence to accelerate neovascularization and subsequent metastasis formation.

Interleukin-33 contributes to both M1 and M2 chemokine marker expression in human macrophages

BACKGROUND

Interleukin-33 is a member of the IL-1 cytokine family whose functions are mediated and modulated by the ST2 receptor. IL-33-ST2 expression and interactions have been explored in mouse macrophages but little is known about the effect of IL-33 on human macrophages. The expression of ST2 transcript and protein levels, and IL-33-mediated effects on M1 (i.e. classical activation) and M2 (i.e. alternative activation) chemokine marker expression in human bone marrow-derived macrophages were examined.

RESULTS

Human macrophages constitutively expressed the membrane-associated (i.e. ST2L) and the soluble (i.e. sST2) ST2 receptors. M2 (IL-4 + IL-13) skewing stimuli markedly increased the expression of ST2L, but neither polarizing cytokine treatment promoted the release of sST2 from these cells. When added to naïve macrophages alone, IL-33 directly enhanced the expression of CCL3. In combination with LPS, IL-33 blocked the expression of the M2 chemokine marker CCL18, but did not alter CCL3 expression in these naive cells. The addition of IL-33 to M1 macrophages markedly increased the expression of CCL18 above that detected in untreated M1 macrophages. Similarly, alternatively activated human macrophages treated with IL-33 exhibited enhanced expression of CCL18 and the M2 marker mannose receptor above that detected in M2 macrophages alone.

CONCLUSIONS

Together, these data suggest that primary responses to IL-33 in bone marrow derived human macrophages favors M1 chemokine generation while its addition to polarized human macrophages promotes or amplifies M2 chemokine expression.

CCL3L1 gene-containing segmental duplications and polymorphisms in CCR5 affect risk of systemic lupus erythaematosus

OBJECTIVES

There is an enrichment of immune response genes that are subject to copy number variations (CNVs). However, there is limited understanding of their impact on susceptibility to human diseases. CC chemokine ligand 3 like-1 (CCL3L1) is a potent ligand for the HIV coreceptor, CC chemokine receptor 5 (CCR5), and we have demonstrated previously an association between CCL3L1-gene containing segmental duplications and polymorphisms in CCR5 and HIV/AIDS susceptibility. Here, we determined the association between these genetic variations and risk of developing systemic lupus erythaematosus (SLE), differential recruitment of CD3+ and CD68+ leukocytes to the kidney, clinical severity of SLE reflected by autoantibody titres and the risk of renal complications in SLE.

METHODS

We genotyped 1084 subjects (469 cases of SLE and 615 matched controls with no autoimmune disease) from three geographically distinct cohorts for variations in CCL3L1 and CCR5.

RESULTS

Deviation from the average copy number of CCL3L1 found in European populations increased the risk of SLE and modified the SLE-influencing effects of CCR5 haplotypes. The CCR5 human haplogroup (HH)E and CCR5-Delta32-bearing HHG*2 haplotypes were associated with an increased risk of developing SLE. An individual's CCL3L1-CCR5 genotype strongly predicted the overall risk of SLE, high autoantibody titres, and lupus nephritis as well as the differential recruitment of leukocytes in subjects with lupus nephritis. The CCR5 HHE/HHG*2 genotype was associated with the maximal risk of developing SLE.

CONCLUSION

CCR5 haplotypes HHE and HHG*2 strongly influence the risk of SLE. The copy number of CCL3L1 influences risk of SLE and modifies the SLE-influencing effects associated with CCR5 genotypes. These findings implicate a key role of the CCL3L1-CCR5 axis in the pathogenesis of SLE.

CC chemokine receptor 5 and CXC chemokine receptor 6 expression by lung CD8+ cells correlates with chronic obstructive pulmonary disease severity

Chronic obstructive pulmonary disease (COPD) is a progressive disease associated with a cellular inflammatory response. CD8(+) T cells are implicated in COPD pathogenesis, and their numbers significantly correlate with the degree of airflow limitation. Dendritic cells (DCs) are important sentinel immune cells, but little is known about their role in initiating and maintaining the CD8 T-cell response in COPD. To investigate the mechanisms for CD8(+) T-cell recruitment to the lung, we used resected human lung tissue to analyze chemokine receptor expression by CD8(+) T cells and chemokine production by CD1a(+) DCs. Among 11 surveyed chemokine receptors, only CC chemokine receptor (CCR5), CXC chemokine receptor (CXCR) 3, and CXCR6 correlated with COPD severity as defined by criteria from the Global Initiative for Chronic Obstructive Lung Disease. The CD8(+) T cells displayed a Tc1, CD45RA(+) effector memory phenotype. CD1a(+) DCs produced the respective ligands for CCR5 and CXCR3, CCL3 and CXCL9, and levels correlated with disease severity. CD1a(+) DCs also constitutively expressed the CXCR6 ligand, CXCL16. In conclusion, we have identified major chemokine elements that potentially mediate CD8(+) T-cell infiltration during COPD progression and demonstrated that CD1a(+) mucosal-associated DCs may sustain CD8(+) T-cell recruitment/retention. Chemokine targeting may prove to be a viable treatment approach.

The role of GM-CSF in adipose tissue inflammation

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a proinflammatory cytokine that has a central action to reduce food intake and body weight. Consistent with this, GM-CSF knockout mice are more obese and hyperphagic than wild-type mice. However, in lung, GM-CSF is an important determinant of macrophage infiltration. Consequently, we sought to determine if GM-CSF might contribute to adipose tissue macrophage accumulation, insulin resistance, and low-grade inflammation that occurs when animals gain weight on a high-fat diet (HFD). We therefore determined how targeted genetic disruption of GM-CSF can affect adipose tissue macrophage and cytokine gene expression as well as glucose homeostasis by performing hyperinsulinemic-euglycemic clamps. The number of macrophages and CCR2 gene expression in adipose tissue of GM-CSF knockout mice was decreased relative to those in wild-type mice, and the adipocyte size of mesenteric fat was increased in GM-CSF knockout mice on a HFD compared with wild-type mice. The level of mRNA of the proinflammatory cytokines interleukin-1beta, tumor necrosis factor-alpha, and macrophage inflammatory protein-1alpha was significantly lower in mesenteric fat of GM-CSF knockout mice on the HFD than in wild-type mice. Using the hyperinsulinemic-euglycemic clamp technique, GM-CSF knockout mice had greater overall insulin sensitivity. This increase was due to enhanced peripheral uptake and utilization of glucose rather than to increased hepatic insulin sensitivity. Collectively, the data suggest that the GM-CSF knockout mutation ameliorates peripheral insulin resistance in spite of increased adiposity by reducing inflammation in adipose tissue in response to a HFD.

Pentosan polysulfate: a novel therapy for the mucopolysaccharidoses

Background

Pentosan polysulfate (PPS) is an FDA-approved, oral medication with anti-inflammatory and pro-chondrogenic properties. We have previously shown that animal models of the mucopolysaccharidoses (MPS) exhibit significant inflammatory disease, contributing to cartilage degeneration. Enzyme replacement therapy (ERT) only partly reduced inflammation, and anti-TNF-alpha antibody therapy significantly enhanced clinical and pathological outcomes. Here we describe the use of PPS for the treatment of MPS type VI rats.

Methodology/Principal Findings

Treatment began during prenatal development and at 1 and 6 months of age. All animals were treated until they were 9 months old. Significant reductions in the serum and tissue levels of several inflammatory markers (e.g., TNF-alpha, MIP-1alpha and RANTES/CCL5) were observed, as was reduced expression of inflammatory markers in cultured articular chondrocytes. ADAMTS-5/aggrecanase-2 levels also were reduced in chondrocytes, consistent with an elevation of serum tissue inhibitor of metalloproteinase 1. Marked improvements in motility and grooming behavior occurred, along with a reduction in eye and nasal secretions and a lessening of the tracheal deformities. MicroCT and radiographic analyses further revealed that the treated MPS skulls were longer and thinner, and that the teeth malocclusions, misalignments and mineral densities were improved. MicroCT analysis of the femurs and vertebrae revealed improvements in trabecular bone mineral densities, number and spacing in a subset of treated MPS animals. Biomechanical assessments of PPS-treated spines showed partially restored torsional behaviors, suggesting increased spinal stability. No improvements were observed in cortical bone or femur length. The positive changes in the PPS-treated MPS VI rats occurred despite glycosaminoglycan accumulation in their tissues.

Conclusions

Based on these findings we conclude that PPS could be a simple and effective therapy for MPS that might provide significant clinical benefits alone and in combination with other therapies.

Epigenetic upregulation of CCL2 and CCL3 via histone modifications in infiltrating macrophages after peripheral nerve injury

To gain insight into the epigenetic regulation of CC-chemokine ligand (CCL) 2 and CCL3, key players in the peripheral sensitization leading to neuropathic pain, we examined the relationship between histone H3 modification and the upregulation of these molecules using a mouse model of neuropathic pain after partial sciatic nerve ligation (PSL). We found that circuiting bone marrow (BM)-derived macrophages infiltrated into the injured sciatic nerve (SCN) using enhanced green fluorescent protein chimeric mice. The mRNA levels of CCL2, CCL3 and their receptors (CCR2 and CCR1/CCR5, respectively) were increased in the injured SCN. Chromatin immunoprecipitation assay revealed that levels of lysine 9-acetylated histone H3 (H3K9Ac) and lysine 4-trimethylated H3 (H3K4me(3)) in the promoter regions of the CCL2 and CCL3 genes were increased in the injured SCN after PSL, indicating the enhancement of gene expression. Immunoreactivity for H3K9Ac and H3K4me(3) was localized in the nuclei of infiltrating BM-derived cells and CCL-expressing cells in the injured SCN. We observed H3K9Ac and H3K4me(3) mainly in the nuclei of recruited macrophages on day 7 after PSL. Furthermore, upregulation of CCLs and CCRs were suppressed by histone acetyltransferase inhibitor, anacardic acid. Taken together, our findings demonstrate that CCL2 and CCL3 are upregulated in the injured peripheral nerve through epigenetic histone modification in infiltrating immune cells such as macrophages. These chemokine cascades may subsequently elicit chronic neuroinflammation following nerve injury.

Expression of MIP-1alpha (CCL3) by a recombinant rabies virus enhances its immunogenicity by inducing innate immunity and recruiting dendritic cells and B cells

Previously, we showed that overexpression of MIP-1alpha in mouse brain further decreased rabies virus (RABV) pathogenicity (L. Zhao, H. Toriumi, Y. Kuang, H. Chen, and Z. F. Fu, J. Virol., 83:11808-11818, 2009). In the present study, the immunogenicity of recombinant RABV expressing MIP-1alpha (rHEP-MIP1alpha) was determined. It was found that intramuscular immunization of BALB/c mice with rHEP-MIP1alpha resulted in a higher level of expression of MIP-1alpha at the site of inoculation, increased recruitment of dendritic cells (DCs) and mature B cells into the draining lymph nodes and the peripheral blood, and higher virus-neutralizing antibody titers than immunization with the parent rHEP and recombinant RABVs expressing RANTES (CCL5) or IP-10 (CXCL10). Our data thus demonstrate that expression of MIP-1alpha not only reduces viral pathogenicity but also enhances immunogenicity by recruiting DCs and B cells to the site of immunization, the lymph nodes, and the blood.

The role of MIP-1 alpha in the development of systemic inflammatory response and organ injury following trauma hemorrhage

Although MIP-1alpha is an important chemokine in the recruitment of inflammatory cells, it remains unknown whether MIP-1alpha plays any role in the development of systemic inflammatory response following trauma-hemorrhage (T-H). C57BL/6J wild type (WT) and MIP-1alpha-deficient (KO) mice were used either as control, subjected to sham operation (cannulation or laparotomy only or cannulation plus laparotomy) or T-H (midline laparotomy, mean blood pressure 35 +/- 5 mmHg for 90 min, followed by resuscitation) and sacrificed 2 h thereafter. A marked increase in serum alpha-glutathione transferase, TNF-alpha, IL-6, IL-10, MCP-1, and MIP-1alpha and Kupffer cell cytokine production was observed in WT T-H mice compared with shams or control. In addition lung and liver tissue edema and neutrophil infiltration (myeloperoxidase (MPO) content) was also increased following T-H in WT animals. These inflammatory markers were markedly attenuated in the MIP-1alpha KO mice following T-H. Furthermore, compared with 2 h, MPO activities at 24 and 48 h after T-H declined steadily in both WT and KO mice. However, normalization of MPO activities to sham levels within 24 h was seen in KO mice but not in WT mice. Thus, MIP-1alpha plays an important role in mediating the acute inflammatory response following T-H. In the absence of MIP-1alpha, acute inflammatory responses were attenuated; rapidly recovered and less remote organ injury was noted following T-H. Thus, interventions that reduce MIP-1alpha levels following T-H should be useful in decreasing the deleterious inflammatory consequence of trauma.

Myeloid cell receptor LRP1/CD91 regulates monocyte recruitment and angiogenesis in tumors

Recruitment of monocytes into sites of inflammation is essential in the immune response. In cancer, recruited monocytes promote invasion, metastasis, and possibly angiogenesis. LDL receptor-related protein (LRP1) is an endocytic and cell-signaling receptor that regulates cell migration. In this study, we isografted PanO2 pancreatic carcinoma cells into mice in which LRP1 was deleted in myeloid lineage cells. Recruitment of monocytes into orthotopic and subcutaneous tumors was significantly increased in these mice, compared with control mice. LRP1-deficient bone marrow-derived macrophages (BMDM) expressed higher levels of multiple chemokines, including, most prominently, macrophage inflammatory protein-1α/CCL3, which is known to amplify inflammation. Increased levels of CCL3 were detected in LRP1-deficient tumor-associated macrophages (TAM), isolated from PanO2 tumors, and in RAW 264.7 macrophage-like cells in which LRP1 was silenced. LRP1-deficient BMDMs migrated more rapidly than LRP1-expressing cells in vitro. The difference in migration was reversed by CCL3-neutralizing antibody, by CCR5-neutralizing antibody, and by inhibiting NF-κB with JSH-23. Inhibiting NF-κB reversed the increase in CCL3 expression associated with LRP1 gene silencing in RAW 264.7 cells. Tumors formed in mice with LRP1-deficient myeloid cells showed increased angiogenesis. Although VEGF mRNA expression was not increased in LRP1-deficient TAMs, at the single-cell level, the increase in TAM density in tumors with LRP1-deficient myeloid cells may have allowed these TAMs to contribute an increased amount of VEGF to the tumor microenvironment. Our results show that macrophage density in tumors is correlated with cancer angiogenesis in a novel model system. Myeloid cell LRP1 may be an important regulator of cancer progression.

Innate cellular sources of interleukin-17A regulate macrophage accumulation in cigarette- smoke-induced lung inflammation in mice

Cigarette smoke (CS) is the major cause of chronic obstructive pulmonary disease (COPD). Interleukin-17A (IL-17A) is a pivotal cytokine that regulates lung immunity and inflammation. The aim of the present study was to investigate how IL-17A regulates CS-induced lung inflammation in vivo. IL-17A knockout (KO) mice and neutralization of IL-17A in wild-type (WT) mice reduced macrophage and neutrophil recruitment and chemokine (C-C motif) ligand 2 (CCL2), CCL3 and matrix metalloproteinase (MMP)-12 mRNA expression in response to acute CS exposure. IL-17A expression was increased in non-obese diabetic (NOD) severe combined immunodeficiency SCID) mice with non-functional B- and T-cells over a 4-week CS exposure period, where macrophages accumulated to the same extent as in WT mice. Gene expression analysis by QPCR (quantitative real-time PCR) of isolated immune cell subsets detected increased levels of IL-17A transcript in macrophages, neutrophils and NK/NKT cells in the lungs of CS-exposed mice. In order to further explore the relative contribution of innate immune cellular sources, intracellular IL-17A staining was performed. In the present study, we demonstrate that CS exposure primes natural killer (NK), natural killer T (NKT) and γδ T-cells to produce more IL-17A protein and CS alone increased the frequency of IL17+ γδ T-cells in the lung, whereas IL-17A protein was not detected in macrophages and neutrophils. Our data suggest that activation of innate cellular sources of IL-17A is an essential mediator of macrophage accumulation in CS-exposed lungs. Targeting non-conventional T-cell sources of IL-17A may offer an alternative strategy to reduce pathogenic macrophages in COPD.

Copy number variation of CCL3-like genes affects rate of progression to simian-AIDS in Rhesus Macaques (Macaca mulatta)

Variation in genes underlying host immunity can lead to marked differences in susceptibility to HIV infection among humans. Despite heavy reliance on non-human primates as models for HIV/AIDS, little is known about which host factors are shared and which are unique to a given primate lineage. Here, we investigate whether copy number variation (CNV) at CCL3-like genes (CCL3L), a key genetic host factor for HIV/AIDS susceptibility and cell-mediated immune response in humans, is also a determinant of time until onset of simian-AIDS in rhesus macaques. Using a retrospective study of 57 rhesus macaques experimentally infected with SIVmac, we find that CCL3L CNV explains approximately 18% of the variance in time to simian-AIDS (p<0.001) with lower CCL3L copy number associating with more rapid disease course. We also find that CCL3L copy number varies significantly (p<10(-6)) among rhesus subpopulations, with Indian-origin macaques having, on average, half as many CCL3L gene copies as Chinese-origin macaques. Lastly, we confirm that CCL3L shows variable copy number in humans and chimpanzees and report on CCL3L CNV within and among three additional primate species. On the basis of our findings we suggest that (1) the difference in population level copy number may explain previously reported observations of longer post-infection survivorship of Chinese-origin rhesus macaques, (2) stratification by CCL3L copy number in rhesus SIV vaccine trials will increase power and reduce noise due to non-vaccine-related differences in survival, and (3) CCL3L CNV is an ancestral component of the primate immune response and, therefore, copy number variation has not been driven by HIV or SIV per se.

CC chemokine ligand 3 deficiency ameliorates diet-induced steatohepatitis by regulating liver macrophage recruitment and M1/M2 status in mice

BACKGROUND AND AIMS

The global prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing. Chemokines and their receptors have potential as therapeutic targets of NAFLD. We investigated the role of CC chemokine ligand 3 (CCL3) in the development of murine and human NAFLD.

METHODS

CCL3-knockout mice (CCL3-/-) and littermate CCL3 wild-type control mice (WT) were fed a high-cholesterol and high-fat (CL) diet for 16 weeks to induce NAFLD. We investigated the impact of CCL3 gene deletion in bone marrow cells and leptin-deficient ob/ob mice on CL diet-induced steatohepatitis. We assayed the serum CCL3 levels in 36 patients with biopsy-proven NAFLD and nine healthy control subjects.

RESULTS

Compared with normal chow (NC), the CL diet induced steatohepatitis and hepatic fibrosis and elevated the plasma CCL3 level. In the liver, CCL3 protein colocalized with F4/80+ macrophages, especially CD11c+ M1-like macrophages, rather than other cell types. CCL3-/- attenuated CL diet-induced steatohepatitis and fibrosis associated with M2-dominant liver macrophages compared with the WT. The reconstitution of bone marrow (BM) cells from CCL3-/- attenuated steatohepatitis in WT mice fed a CL diet. Furthermore, crossing CCL3-/- onto the ob/ob background prevented CL diet-induced NAFLD in ob/ob mice, which was associated with a lesser inflammatory phenotype of liver macrophages. Also, the serum and hepatic levels of CCL3 were significantly increased in patients with non-alcoholic steatohepatitis (NASH) compared to those with simple fatty liver (NAFL) and healthy subjects.

CONCLUSION

Our data indicate that CCL3 facilitates macrophage infiltration into the liver and M1 polarization in the progression of steatohepatitis and highlight the need for further studies to determine the effect of CCL3-CCR1 and -CCR5 signaling blockade on the treatment of NAFLD.

CCAAT/enhancer-binding protein β and NF-κB mediate high level expression of chemokine genes CCL3 and CCL4 by human chondrocytes in response to IL-1β

A large set of chemokines is highly up-regulated in human chondrocytes in response to IL-1β (Sandell, L. J., Xing, X., Franz, C., Davies, S., Chang, L. W., and Patra, D. (2008) Osteoarthr. Cartil. 16, 1560-1571). To investigate the mechanism of transcriptional regulation, deletion constructs of selected chemokine gene promoters, the human CCL3 (MIP-1α) and CCL4 (MIP-1β), were transfected into human chondrocytes with or without IL-1β. The results show that an IL-1β-responsive element is located between bp -300 and -140 of the CCL3 promoter and between bp -222 and -100 of the CCL4 promoter. Because both of these elements contain CCAAT/enhancer-binding protein β (C/EBPβ) motifs, the function of C/EBPβ was examined. IL-1β stimulated the expression of C/EBPβ, and the direct binding of C/EBPβ to the C/EBPβ motif was confirmed by EMSA and ChIP analyses. The -300 bp CCL3 promoter and -222 bp CCL4 promoter were strongly up-regulated by co-transfection with the C/EBPβ expression vector. Mutation of the C/EBPβ motif and reduction of C/EBPβ expression by siRNA decreased the up-regulation. Additionally, another cytokine-related transcription factor, NF-κB, was also shown to be involved in the up-regulation of chemokines in response to IL-1β, and the binding site was identified. The regulation of C/EBPβ and NF-κB was confirmed by the inhibition by C/EBPβ and NF-κB and by transfection with C/EBPβ and NF-κB expression vectors in the presence or absence of IL-1β. Taken together, our results suggest that C/EBPβ and NF-κB are both involved in the IL-1β-responsive up-regulation of chemokine genes in human chondrocytes. Time course experiments indicated that C/EBPβ gradually and steadily induces chemokine up-regulation, whereas NF-κB activity was highest at the early stage of chemokine up-regulation.

Inflammatory monocytes and neutrophils are licensed to kill during memory responses in vivo

Immunological memory is a hallmark of B and T lymphocytes that have undergone a previous encounter with a given antigen. It is assumed that memory cells mediate better protection of the host upon re-infection because of improved effector functions such as antibody production, cytotoxic activity and cytokine secretion. In contrast to cells of the adaptive immune system, innate immune cells are believed to exhibit a comparable functional effector response each time the same pathogen is encountered. Here, using mice infected by the intracellular bacterium Listeria monocytogenes, we show that during a recall bacterial infection, the chemokine CCL3 secreted by memory CD8⁺ T cells drives drastic modifications of the functional properties of several populations of phagocytes. We found that inflammatory ly6C⁺ monocytes and neutrophils largely mediated memory CD8⁺ T cell bacteriocidal activity by producing increased levels of reactive oxygen species (ROS), augmenting the pH of their phagosomes and inducing antimicrobial autophagy. These events allowed an extremely rapid control of bacterial growth in vivo and accounted for protective immunity. Therefore, our results provide evidence that cytotoxic memory CD8⁺ T cells can license distinct antimicrobial effector mechanisms of innate cells to efficiently clear pathogens.

The immune system comprises white blood cells that belong to the innate or the adaptive immune arms. Adaptive immune cells such as T and B lymphocytes can give rise to memory cells which mediate long-lived immunity against pathogens. During a recall infection, innate immune phagocytic cells such as monocytes and neutrophils can be critical to kill microbial pathogens inside infected tissues. Whether and how such antimicrobial features of phagocytic cells of the innate immune system are modulated during a memory response in a vaccinated host is not known. The present report shows that cytolytic memory T lymphocytes, an important subpopulation of effector T cells, can drastically enhance the functional killing capacities of monocytes and neutrophils for optimized pathogen clearance from infected hosts. These phagocytes exhibit enhanced generation of oxidative burst, increased phagosomal pH and autophagy, three mechanisms that lead to intracellular pathogen death. This result is important since it suggests that modulating innate immune cells effector activities could be an interesting strategy to enhance vaccine efficacy.

Relationship between the inflammatory molecular profile of breast carcinomas and distant metastasis development

Inflammatory conditions may promote tumor progression and aggressiveness. In previous reports, we found a group of breast cancer tumors characterized by metalloprotease-11 (MMP-11) expression by intratumoral mononuclear inflammatory cells (MICs), which was associated with distant metastasis development. Thus, in the present study we evaluated the relationship between MMP-11 expression by MICs, distant metastasis development, and a wide panel of inflammatory factors in breast carcinoma. In an initial approach, we analyzed 65 factors associated with tumor progression and inflammation, in a tumor population classified in good or bad prognosis, based on MMP-11 expression by intratumoral MICs. The most differentially expressed factors were then analyzed in a wider tumor population classified according to MMP-11 expression by MICs and also according to metastasis development. These analyses were carried out by Real-time PCR. The results showed that of the 65 starting factors analyzed, those related with MMP-11 expression by MICs were: IL-1, −5, −6, −8, −17, −18, MMP-1, TIMP-1, ADAM-8, −10, −15, −23, ADAMTS-1, −2, −15, Annexin A2, IFNβ, Claudin-3, CCL-3, MyD88, IRAK-4 and NFκB. Of them, factors more differentially expressed between both groups of tumors were IL-1, IL-5, IL-6, IL-17, IFNβ and NFκB. Thereafter, we confirmed in the wider tumor population, that there is a higher expression of those factors in tumors infiltrated by MMP-11 positive MICs. Altogether these results indicate that tumors developing worse prognosis and identified by MMP-11 expression by intratumoral MICs, shows an up-regulation of inflammatory-related genes.

Intermittent Fasting Improves Glucose Tolerance and Promotes Adipose Tissue Remodeling in Male Mice Fed a High-Fat Diet

Obesity is associated with increased macrophage and extracellular matrix accumulation in adipose tissue, which can be partially reversed following weight loss by daily caloric restriction. This study examined the effects of 8 weeks of intermittent fasting (IF; 24-hour fast on 3 nonconsecutive days per week) in mice fed a chow or high-fat diet (HFD; 43% fat) on markers of adipose tissue inflammation and fibrosis. We found that IF decreased energy intake, body weight, and fat cell size in HFD-fed mice and decreased fat mass and improved glucose tolerance in chow- and HFD-fed mice. IF decreased mRNA levels of macrophage markers (Lgals3, Itgax, Ccl2, and Ccl3) in inguinal and gonadal fat, as well as adipose tissue macrophage numbers in HFD-fed mice only, and altered genes involved in NLRP3 inflammasome pathway in both diet groups. IF increased mRNA levels of matrix metallopeptidase 9, which is involved in extracellular matrix degradation, and reduced mRNA levels of collagen 6 α-1 and tissue inhibitor of matrix metallopeptidase 1, as well as fibrosis in gonadal fat in HFD-fed mice. In summary, our results show that intermittent fasting improved glucose tolerance in chow- and HFD-fed mice and ameliorated adipose tissue inflammation and fibrosis in HFD-fed mice.

The chemokine MIP1alpha/CCL3 determines pathology in primary RSV infection by regulating the balance of T cell populations in the murine lung

BACKGROUND

CD8 T cells assist in the clearance of respiratory syncytial virus (RSV) infection from the lungs. However, disease after RSV infection is in part caused by excessive T cell activity, and a balance is therefore needed between beneficial and harmful cellular immune responses. The chemokine CCL3 (MIP1alpha) is produced following RSV infection and is broadly chemotactic for both T cells and natural killer (NK) cells. We therefore investigated its role in RSV disease.

METHODOLOGY/PRINCIPAL FINDINGS

CCL3 was produced biphasically, in both the early (day 1) and late (day 6-7) stages of infection. CCL3 depletion did not alter the recruitment of natural killer (NK) cells to the lungs during the early stage, but depletion did affect the later adaptive phase. While fewer T cells were recruited to the lungs of either CCL3 knockout or anti-CCL3 treated RSV infected mice, more RSV-specific pro-inflammatory T cells were recruited to the lung when CCL3 responses were impaired. This increase in RSV-specific pro-inflammatory T cells was accompanied by increased weight loss and illness after RSV infection.

CONCLUSIONS/SIGNIFICANCE

CCL3 regulates the balance of T cell populations in the lung and can alter the outcome of RSV infection. Understanding the role of inflammatory mediators in the recruitment of pathogenic T cells to the lungs may lead to novel methods to control RSV disease.