Eotaxin/CCL11 expression by infiltrating macrophages in rat heart transplants during ongoing acute rejection

ANGPTL3 accelerates atherosclerotic progression via direct regulation of M1 macrophage activation in plaque

INTRODUCTION

The N-terminal domain of angiopoietin-like protein 3 (ANGPTL3) inhibits lipoprotein lipase activity. Its C-terminal fibrinogen-like (FBN) domain is a ligand of macrophage integrin αvβ3.

OBJECTIVES

ANGPTL3 might home to plaque where it directly regulates macrophage function via integrin αvβ3 for atherosclerosis progression.

METHODS

Ldlr-/- mice on a high-fat diet and ApoE-/- mice on a chow diet were received adeno-associated virus (AAV)-mediated Angptl3 gene transfer and followed up for 12 weeks. ApoE-/- mice were injected AAV containing FLAG-tagged Angptl3 cDNA for tracing. Atherosclerotic features were compared between Angptl3-/-ApoE-/- mice and ApoE-/- littermates. THP-1 cells were exposed to 0 or 50 μg/ml ANGPTL3 FBN domain for 24 h to evaluate Toll-like receptor (TLR)4 expression using western blot analysis and circulating cytokine and chemokine profiles by the MILLIPLEX MAP assay. Phospho-proteomic profile was established in ANGPTL3-treated macrophages. Integrin β3 deficient THP-1 cells were obtained by sgRNAs targeting RGD sequence using Lentivirus-Cas9 system.

RESULTS

Angptl3 overexpression increased atherosclerotic progression and CD68+ macrophages in plaque (p < 0.05 for all). By immunostaining, FLAG+ cells were identified in plaque of gene transferred ApoE-/- mice. Fluorescent immunostaining detected co-localisation of Angptl3 and CD68 in plaque macrophages. Phospho-proteomic analysis revealed that Angptl3 induced phosphorylation of proteins that were involved in the IL-17 signalling pathway in THP-1 cells. In vitro, ANGPTL3 treatment increased the production of interleukin (IL)-1β and tumour necrosis factor-α in THP-1 cells (p < 0.05 for both). Exposure of ANGPTL3 to THP-1 cells induced Akt phosphorylation which was weakened in integrin β3 deficient ones. ANGPTL3 elevated TLR4 expression via Akt phosphorylation. In response to lipopolysaccharide, nuclear factor-κB activity was 2.2-fold higher in THP-1 cells pre-treated with ANGPTL3 than in untreated cells (p < 0.05).

CONCLUSIONS

Targeting ANGPTL3 could yield a dual benefit of lowering lipid levels in the blood and suppressing macrophage activation in plaque.

Circulating virome and inflammatory proteome in patients with ST-elevation myocardial infarction and primary ventricular fibrillation

Primary ventricular fibrillation (PVF) is a life-threatening complication of ST-segment elevation myocardial infarction (STEMI). It is unclear what roles viral infection and/or systemic inflammation may play as underlying triggers of PVF, as a second hit in the context of acute ischaemia. Here we aimed to evaluate whether the circulating virome and inflammatory proteome were associated with PVF development in patients with STEMI. Blood samples were obtained from non-PVF and PVF STEMI patients at the time of primary PCI, and from non-STEMI healthy controls. The virome profile was analysed using VirCapSeq-VERT (Virome Capture Sequencing Platform for Vertebrate Viruses), a sequencing platform targeting viral taxa of 342,438 representative sequences, spanning all virus sequence records. The inflammatory proteome was explored with the Olink inflammation panel, using the Proximity Extension Assay technology. After analysing all viral taxa known to infect vertebrates, including humans, we found that non-PVF and PVF patients only significantly differed in the frequencies of viruses in the Gamma-herpesvirinae and Anelloviridae families. In particular, most showed a significantly higher relative frequency in non-PVF STEMI controls. Analysis of systemic inflammation revealed no significant differences between the inflammatory profiles of non-PVF and PVF STEMI patients. Inflammatory proteins associated with cell adhesion, chemotaxis, cellular response to cytokine stimulus, and cell activation proteins involved in immune response (IL6, IL8 CXCL-11, CCL-11, MCP3, MCP4, and ENRAGE) were significantly higher in STEMI patients than non-STEMI controls. CDCP1 and IL18-R1 were significantly higher in PVF patients compared to healthy subjects, but not compared to non-PVF patients. The circulating virome and systemic inflammation were not associated with increased risk of PVF development in acute STEMI. Accordingly, novel strategies are needed to elucidate putative triggers of PVF in the setting of acute ischaemia, in order to reduce STEMI-driven sudden death burden.

Pressure overload generates a cardiac-specific profile of inflammatory mediators

Mechanisms that contribute to myocardial fibrosis, particularly in response to left ventricular pressure overload (LVPO), remain poorly defined. To test the hypothesis that a myocardial-specific profile of secreted factors is produced in response to PO, levels of 44 factors implicated in immune cell recruitment and function were assessed in a murine model of cardiac hypertrophy and compared with levels produced in a model of pulmonary fibrosis (PF). Mice subjected to PO were assessed at 1 and 4 wk. Protein from plasma, LV, lungs, and kidneys were analyzed by specific protein array analysis in parallel with protein from mice subjected to silica-instilled PF. Of the 44 factors assessed, 13 proteins were elevated in 1-wk PO myocardium, whereas 18 proteins were found increased in fibrotic lung. Eight of those increased in 1-wk LVPO were not found to be increased in fibrotic lungs (CCL-11, CCL-12, CCL-17, CCL-19, CCL-21, CCL-22, IL-16, and VEGF). Additionally, six factors were increased in plasma of 1-wk LVPO in the absence of increases in myocardial levels. In contrast, in mice with PF, no factors were found increased in plasma that were not elevated in lung tissue. Of those factors increased at 1 wk, only TIMP-1 remained elevated at 4 wk of LVPO. Immunohistochemistry of myocardial vasculature at 1 and 4 wk revealed similar amounts of total vasculature; however, evidence of activated endothelium was observed at 1 wk and, to a lesser extent, at 4 wk LVPO. In conclusion, PO myocardium generated a unique signature of cytokine expression versus that of fibrotic lung.NEW & NOTEWORTHY Myocardial fibrosis and the resultant increases in myocardial stiffness represent pivotal consequences of chronic pressure overload (PO). In this study, cytokine profiles produced in a murine model of cardiac fibrosis induced by PO were compared with those produced in response to silica-induced lung fibrosis. A unique profile of cardiac tissue-specific and plasma-derived factors generated in response to PO are reported.

Role of eotaxin-1/CCL11 in sepsis-induced myocardial injury in elderly patients

Myocardial injury is a serious complication of sepsis. The present study aimed to identify potential biomarkers of sepsis-induced myocardial injury. Differentially expressed genes (DEGs) in patients and mice with sepsis-induced myocardial injury were identified via bioinformatic analysis. The identified DEG was tested in elderly patients with sepsis-induced myocardial injury. We identified 19 co-expressed DEGs. The most significant DEG was eotaxin-1/CCL11. We enrolled 25 controls without infections and 28 patients with sepsis-induced myocardial injury. Six of patients died within 30 days. Circulating eotaxin-1/CCL11 levels were significantly higher in patients with sepsis-induced myocardial injury than controls and were higher in non-survivors than survivors (both P < 0.01). Eotaxin-1/CCL11 was positively correlated with troponin I (r=0.48, P=0.01), B-type natriuretic peptide (BNP, r=0.44, P=0.02), and white blood cell (WBC) count (r=0.41, P=0.03). For the prediction of 30-day mortality, eotaxin-1/CCL11 had the greatest discriminatory ability (AUC 0.97) compared with troponin I (AUC 0.89), BNP (AUC 0.80), and WBC count (AUC 0.86). Taken together, eotaxin-1/CCL11 was upregulated in sepsis-injured myocardium and circulating eotaxin-1/CCL11 was a biomarker for predicting severity and mortality of elderly patients with sepsis-induced myocardial injury. These results suggest that eotaxin-1/CCL11 may become a useful biomarkers and potential therapeutic target for sepsis-induced myocardial injury.

Hepatic stellate cells secreting WFA+ -M2BP: Its role in biological interactions with Kupffer cells

BACKGROUND AND AIM

Hepatic stellate cells (HSCs) play a central role in hepatic fibrosis and are regulated by Kupffer cells (KCs). Wisteria floribunda agglutinin-positive Mac-2 binding protein (WFA⁺ -M2BP) was recently identified as a serum marker for hepatic fibrosis. Although WFA⁺ -M2BP was identified as a ligand of Mac-2, the function of WFA⁺ -M2BP in hepatic fibrosis remains unclear.

METHODS

Liver specimens were obtained from five patients with cirrhosis, five with chronic hepatitis, and five without hepatic fibrosis. WFA⁺ -M2BP kinetics were evaluated histologically and in subpopulations of liver cells such as HSCs, KCs, endothelial cells, biliary epithelial cells, and hepatocytes in in vitro culture. The function of WFA⁺ -M2BP in activated HSCs was evaluated using immunoblot analysis.

RESULTS

Numbers of WFA⁺ -M2BP-positive cells in liver tissues increased with fibrosis stage. There were significant differences in WFA⁺ -M2BP levels between fibrosis stages F0 and F1-2 (P = 0.012) and between fibrosis stages F1-2 and F3-4 (P < 0.001). HSCs were the source of WFA⁺ -M2BP secretion in in vitro cultures of liver cells, as determined by sandwich immunoassay. Cells of the human HSC line LX-2 also secreted WFA⁺ -M2BP. Histologically, tissue sections showed that WFA⁺ -M2BP was located in Mac-2-expressing KCs. In vitro assays showed that exogenous WFA⁺ -M2BP stimulation enhanced Mac-2 expression in KCs and that HSCs co-cultured with KCs increased α-smooth muscle actin expression. Finally, Mac-2-depleted KCs with short interfering RNA had reduced α-smooth muscle actin expression following co-culturing with HSCs.

CONCLUSIONS

WFA⁺ -M2BP from HSCs induces Mac-2 expression in KCs, which in turn activates HSCs to be fibrogenic.

The putative role of mast cells in lung transplantation

Mast cells (MCs) were primarily recognized as effector cells of allergy. These cells are acting predominantly at the interface between the host and the external environment, such as skin, gastrointestinal and the respiratory tract. Only recently, MCs have gained increased recognition as cells of functional plasticity with immune-regulatory properties that influence both the innate and the adaptive immune response in inflammatory disorders, cancer and transplantation. Through the secretion of both proinflammatory and antiinflammatory mediators, MCs can either ameliorate or deteriorate the course and outcome in lung transplantation. Recent research from other models recognized the immune-protective activity of MCs including its role as an important source of IL-10 and TGF-β for the modulation of alloreactive T cell responses or assistance in Treg activity. This paper summarizes the current understanding of MCs in lung transplantation and discusses MC-mediated immune-mechanisms by which the outcome of the engrafted organ is modulated.

Activation of eosinophil CCR3 signaling and eotaxin using a bioinformatics analysis of a mouse model of obliterative airway disease

The role of eosinophils in the development and progression of chronic allograft rejection is recognized in multiple organ transplantation settings. The CCR3 signaling pathway is one of the key regulatory pathways in eosinophil migration to the engrafted tissue. Eotaxin is a ligand for CCR3 and reflects eosinophilic inflammation, which can lead to fibrosis. We hypothesized that the CCR3 pathway would be upregulated in obliterative airway disease (OAD) in an established model of chronic airway allograft rejection. The mouse gene microarray data from a heterotopic mouse model of OAD in the NIH Gene Expression Omnibus (GEO) repository were analyzed for differentially expressed eosinophil pathways, using the Partek Suite and Ingenuity Pathway Analysis. A P value of <0.005 was defined as significant for differential expression, and P value of <0.05 for pathways. Day 25 allografts were defined as chronic allograft rejection and day 4 as acute allograft rejection. The isografts and allografts at day 25 showed significant upregulation of the eosinophil CCR3 pathway (P=0.04), based on the analysis of 1,299 uniquely expressed genes. The isografts at day 4 were compared with those at day 25 based on the identification of 1,859 unique genes, and there was a trend toward the CCR3 pathway upregulation over time (P=0.06). CCR3 pathways were not upregulated during the progression of alloimmune rejection in the allografts at day 4 versus day 25 in comparison, based on the analysis of 1,603 genes. Eotaxin was upregulated in chronic allograft rejection by 2.5-fold. The eosinophil signaling pathway CCR3 and eotaxin were significantly expressed in chronic allograft rejection and our results imply a role in controlling early alloimmune damage in controls.

Eotaxin/CCL11 in idiopathic retroperitoneal fibrosis

BACKGROUND

Idiopathic retroperitoneal fibrosis (IRF) is a rare fibro-inflammatory disorder characterized by a periaortic tissue which often encases the ureters causing acute renal failure. IRF histology shows fibrosis and a chronic inflammatory infiltrate with frequent tissue eosinophilia. We assessed a panel of molecules promoting eosinophilia and fibrosis in IRF patients and performed an immunogenetic study.

METHODS

Serum levels of eotaxin/CCL11, regulated and normal T-cell expressed and secreted (RANTES), granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-5, platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) were measured using a multiplex assay in 24 newly diagnosed, untreated IRF patients and 14 healthy controls. Retroperitoneal biopsies (available in 8/24 patients) were histologically evaluated to assess eosinophil infiltration, whereas mast cells (MCs) were identified by immunohistochemical analysis for human tryptase. Immunohistochemistry for eotaxin/CCL11 and its receptor CCR3 was also performed. Six single nucleotide polymorphisms (SNPs) within the CCL11 gene (rs6505403, rs1860184, rs4795896, rs17735961, rs16969415 and rs17809012) were investigated in 142 IRF patients and 214 healthy controls.

RESULTS

Serum levels of eotaxin/CCL11 were higher in IRF patients than in controls (P = 0.009). Eotaxin/CCL11 drives tissue infiltration of eosinophils and MCs, which can promote fibrosis. Eosinophilic infiltration was prominent (>5 cells/hpf) in five (62.5%) cases, and abundant tryptase-positive MCs were found in all cases; notably, MCs were in a degranulating state. Immunohistochemistry showed that CCL11 was highly produced by infiltrating mononuclear cells and that its receptor CCR3 was expressed by infiltrating eosinophils, MCs, lymphocytes and fibroblasts. None of the tested CCL11 SNPs showed disease association, but the TTCCAT haplotype was significantly associated with IRF (P = 0.0005).

CONCLUSIONS

These findings suggest that the eotaxin/CCL11-CCR3 axis is active in IRF and may contribute to its pathogenesis; the TTCCAT haplotype within the CCL11 gene is significantly associated with IRF.

Eotaxin/CCL11 levels correlate with myocardial fibrosis and mast cell density in native and transplanted rat hearts

INTRODUCTION

Myocardial fibrosis contributes to hemodynamic and cardiac functional alterations commonly observed posttransplantation. Cardiac mast cells (MC) have been linked to fibrosis in posttransplantation hearts. Eotaxin, which has been shown to be involved in fibrogenesis, has been demonstrated to be increased in production in cardiac macrophages. The aim of our study was to correlate myocardial fibrosis during heart transplant rejection in the rat with eotaxin/chemokine [c-c motif] ligand 11 (CCL11) expression, and with various subtypes of infiltrating cardiac MC, namely connective-type MC (CTMC) and mucosa-type MC (MMC).

METHODS

We used tissues from 2 previous studies of ongoing acute rejection in allogeneic Brown-Norway to Lewis rat and an isogeneic Brown-Norway to Brown-Norway heterotopic heart transplantation models under cyclosporin/prednisolone immunosuppression. Collagen fibrils were stained with Masson's trichrome with myocardial fibrosis expressed as percent fibrotic area per total section area. Eotaxin/CCL11 previously measured in heart tissue using enzyme-linked immunosorbent assay (ELISA) was correlated with the extent of myocardial fibrosis. We compared values from native hearts (n = 4) as well as transplants on days 5, 16, and 28 (n = 4 in each group).

RESULTS

The area of myocardial fibrosis was significantly increased in the allogeneic compared with the isogeneic group at day 16 (38% vs 21%) and at day 28 (49% vs 22%) after transplantation. Myocardial fibrosis correlated significantly with eotaxin/CCL11 concentrations and the density of MMC, but not with CTMC in heart tissue.

CONCLUSIONS

Eotaxin-triggered MC infiltration of the heart may contribute to myocardial fibrosis after transplantation. Targeting eotaxin/CCL11 with monoclonal antibodies, such as bertilimumab, could reduce MC infiltration, possibly resulting in decreased myocardial fibrosis and improved contractile function after heart transplantation.

Attenuated atherosclerosis upon IL-17R signaling disruption in LDLr deficient mice

Atherosclerosis is an inflammatory disease characterized by the influx of macrophages and T cells and IL-17 may connect innate and adaptive immune responses involved in atherogenesis. We investigated the role of IL-17 receptor signaling in atherosclerosis and transplanted LDLr deficient recipient mice with IL-17R deficient bone marrow. Induction of atherosclerosis by Western-type diet induced a 46% reduction in lesion size in the aortic root and the plaque composition revealed no significant changes in collagen content and neutrophil counts, but a reduction in mast cell number and an increase in macrophage number. In addition, we observed a decrease in anti-oxLDL antibodies of the IgG class upon IL-17R BMT, while introduction of IL-17R deficient bone marrow resulted in a reduced IL-6 production and an increased IL-10 production. In conclusion, signaling via the IL-17 receptor in bone marrow derived cells enhances the process of atherosclerosis.