Mast cells are major effector cells in allergy and host defense responses. Their increased number and state of activation in perivascular tissue during atherosclerosis may point to a role in ...cardiovascular disorders. In the present study, we investigated the contribution of perivascular mast cells to atherogenesis and plaque stability in apolipoprotein E-deficient mice.
We show here that episodes of systemic mast cell activation during plaque progression in mice leads to robust plaque expansion. Targeted activation of perivascular mast cells in advanced plaques sharply increases the incidence of intraplaque hemorrhage, macrophage apoptosis, vascular leakage, and CXCR2/VLA-4-mediated recruitment of leukocytes to the plaque. Importantly, treatment with the mast cell stabilizer cromolyn does prevent all the adverse phenomena elicited by mast cell activation.
This is the first study to demonstrate that mast cells play a crucial role in plaque progression and destabilization in vivo. We propose that mast cell stabilization could be a new therapeutic approach to the prevention of acute coronary syndromes.
MicroRNAs are being used in the oncology field to characterize tumors and predict the survival of cancer patients. Here, we explored the potential of microRNAs as biomarkers for coronary artery ...disease (CAD) and acute coronary syndromes.
Using real-time PCR-based profiling, we determined the microRNA signature of peripheral blood mononuclear cells (PBMCs) from stable and unstable CAD patients and unaffected controls. 129 of 157 microRNAs measured were expressed by PBMCs and low variability between separate PBMC pools was observed. The presence of CAD in general coincided with a marked 5-fold increase (
P
<
0.001) in the relative expression level of miR-135a, while the expression of miR-147 was 4-fold decreased (
P
<
0.05) in PBMCs from CAD patients as compared to controls, resulting in a 19-fold higher miR-135a/miR-147 ratio (
P
<
0.001) in CAD. MicroRNA/target gene/biological function linkage analysis suggested that the change in PBMC microRNA signature in CAD patients is probably associated with a change in intracellular cadherin/Wnt signaling. Interestingly, unstable angina pectoris patients could be discriminated from stable patients based upon their relatively high expression level of a cluster of three microRNAs including miR-134, miR-198, and miR-370, suggesting that the microRNA signatures can be used to identify patients at risk for acute coronary syndromes.
The present study is the first to show that microRNA signatures can possibly be utilized to identify patients exhibiting atherosclerotic CAD in general and those at risk for acute coronary syndromes. Our findings highlight the importance of microRNAs signatures as novel tool to predict clinical disease outcomes.
BACKGROUND—Matrix metalloproteinase-9 (MMP-9) is involved in atherosclerosis and elevated MMP-9 activity has been found in unstable plaques, suggesting a crucial role in plaque rupture. This study ...aims to assess the effect of MMP-9 on plaque stability in apolipoprotein E-deficient mice at different stages of plaque progression.
METHODS AND RESULTS—Atherosclerotic lesions were elicited in carotid arteries by perivascular collar placement. MMP-9 overexpression in intermediate or advanced plaques was effected by intraluminal incubation with an adenovirus (Ad.MMP-9). A subset was coincubated with Ad.TIMP-1. Mock virus served as a control. Plaques were analyzed histologically. In intermediate lesions, MMP-9 overexpression induced outward remodeling, as shown by a 30% increase in media size (p=0.03). In both intermediate and advanced lesions, prevalence of vulnerable plaque morphology tended to be increased. Half of MMP-9–treated lesions displayed intraplaque hemorrhage, whereas in controls and the Ad.MMP-9/Ad.TIMP-1 group this was 8% and 16%, respectively (p=0.007). Colocalization with neovessels may point to neo-angiogenesis as a source for intraplaque hemorrhage.
CONCLUSION—These data show a differential effect of MMP-9 at various stages of plaque progression and suggest that lesion-targeted MMP-9 inhibition might be a valuable therapeutic modality in stabilizing advanced plaques, but not at earlier stages of lesion progression.
While the promise of oligonucleotide therapeutics, such as (chemically modified) ASO (antisense oligonucleotides) and short interfering RNAs, is undisputed from their introduction onwards, their ...unfavorable pharmacokinetics and intrinsic capacity to mobilize innate immune responses, were limiting widespread clinical use. However, these major setbacks have been tackled by breakthroughs in chemistry, stability and delivery. When aiming an intervention hepatic targets, such as lipid and sugar metabolism, coagulation, not to mention cancer and virus infection, introduction of N-acetylgalactosamine aided targeting technology has advanced the field profoundly and by now a dozen of N-acetylgalactosamine therapeutics for these indications have been approved for clinical use or have progressed to clinical trial stage 2 to 3 testing. This technology, in combination with major advances in oligonucleotide stability allows safe and durable intervention in targets that were previously deemed undruggable, such as Lp(a) and PCSK9 (proprotein convertase subtilisin/kexin type 9), at high efficacy and specificity, often with as little as 2 doses per year. Their successful use even the most visionary would not have predicted 2 decades ago. Here, we will review the evolution of N-acetylgalactosamine technology. We shall outline their fundamental design principles and merits, and their application for the delivery of oligonucleotide therapeutics to the liver. Finally, we will discuss the perspectives of N-acetylgalactosamine technology and propose directions for future research in receptor targeted delivery of these gene medicines.
Growth differentiation factor (GDF) 15 is a member of the transforming growth factor β (TGF-β) superfamily, which operates in acute phase responses through a currently unknown receptor. Elevated ...GDF-15 serum levels were recently identified as a risk factor for acute coronary syndromes. We show that GDF-15 expression is up-regulated as disease progresses in murine atherosclerosis and primarily colocalizes with plaque macrophages. Hematopoietic GDF-15 deficiency in low density lipoprotein receptor(-/-) mice led to impaired initial lesion formation and increased collagen in later lesions. Although lesion burden in GDF-15(-/-) chimeras was unaltered, plaques had reduced macrophage infiltrates and decreased necrotic core formation, all features of improved plaque stability. In vitro studies pointed to a TGFβRII-dependent regulatory role of GDF-15 in cell death regulation. Importantly, GDF-15(-/-) macrophages displayed reduced CCR2 expression, whereas GDF-15 promoted macrophage chemotaxis in a strictly CCR2- and TGFβRII-dependent manner, a phenomenon which was not observed in G protein-coupled receptor kinase 2(+/-) macrophages. In conclusion, GDF-15 deletion has a beneficial effect both in early and later atherosclerosis by inhibition of CCR2-mediated chemotaxis and by modulating cell death. Our study is the first to identify GDF-15 as an acute phase modifier of CCR2/TGFβRII-dependent inflammatory responses to vascular injury.
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.
Uncontrolled interferon γ (IFNγ)-mediated T-cell responses to commensal microbiota are a driver of inflammatory bowel disease (IBD). Interleukin-10 (IL-10) is crucial for controlling these T-cell ...responses, but the precise mechanism of inhibition remains unclear. A better understanding of how IL-10 exerts its suppressive function may allow identification of individuals with suboptimal IL-10 function among the heterogeneous population of IBD patients. Using cells from patients with an IL10RA deficiency or STAT3 mutations, we demonstrate that IL-10 signaling in monocyte-derived dendritic cells (moDCs), but not T cells, is essential for controlling IFNγ-secreting CD4
T cells. Deficiency in IL-10 signaling dramatically increased IL-1β release by moDCs. IL-1β boosted IFNγ secretion by CD4
T cells either directly or indirectly by stimulating moDCs to secrete IL-12. As predicted a signature of IL-10 dysfunction was observed in a subgroup of pediatric IBD patients having higher IL-1β expression in activated immune cells and macroscopically affected intestinal tissue. In agreement, reduced IL10RA expression was detected in peripheral blood mononuclear cells and a subgroup of pediatric IBD patients exhibited diminished IL-10 responsiveness. Our data unveil an important mechanism by which IL-10 controls IFNγ-secreting CD4
T cells in humans and identifies IL-1β as a potential classifier for a subgroup of IBD patients.
Previous studies have shown that during the lifespan of red blood cells (RBCs) 20% of hemoglobin is lost by shedding of hemoglobin-containing vesicles. However, the fate of these vesicles is unknown. ...To study this fate we used a rat model, after having established that rat RBCs lose hemoglobin in the same way as human RBCs, and that RBC-derived vesicles are preferentially labeled by Na251 CrO4. Such labeled vesicles were injected into recipient rats. Within 5 minutes, 80% of the radioactivity was cleared from the circulation with a concomitant uptake by the liver of 55% of the injected dose. After 30 minutes, Kupffer cells contained considerable amounts of hemoglobin and were shown to be responsible for 92% of the liver uptake. Vesicle clearance from the blood as well as liver uptake were significantly inhibited by preinjection of the scavenger-receptor ligands polyinosinic acid and phosphatidylserine. We conclude that in rats Kupffer cells rapidly remove RBC-derived vesicles from the circulation, mainly by scavenger receptors. The same mechanism is likely to be responsible for the elimination of human RBC vesicles, thereby constituting an important pathway for the breakdown of RBCs in humans.
OBJECTIVE—The chemokine receptor CXCR3 is implicated in migration of leukocytes to sites of inflammation. Antagonizing CXCR3 may be a strategy to inhibit inflammation-induced leukocyte migration and ...subsequently reduce atherosclerosis. We used the CXCR3 specific antagonist NBI-74330 to block CXCR3-mediated signaling in peritonitis and diet-induced atherosclerosis.
METHODS AND RESULTS—Antagonizing CXCR3 with NBI-74330 resulted in a significant reduction in CD4 T cell and macrophage migration to the peritoneal cavity, which was as shown in ex vivo migration studies totally CXCR3 dependent. Atherosclerotic lesion formation in the aortic valve leaflet area and the entire aorta was significantly inhibited in NBI-74330 treated mice. Lymph nodes draining from the aortic arch were significantly smaller in treated mice and were enriched in regulatory T cells and contained fewer activated T cells, whereas the markers for regulatory T cells within the lesion were enhanced after NBI-74330 treatment.
CONCLUSION—This study shows for the first time that treatment with a CXCR3 antagonist results in attenuating atherosclerotic lesion formation by blocking direct migration of CXCR3 effector cells from the circulation into the atherosclerotic plaque and by beneficially modulating the inflammatory response in the lesion and the lymph nodes draining from the atherosclerotic lesion.
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