Inhibition of lysophosphatidic acid receptors 1 and 3 attenuates atherosclerosis development in LDL-receptor deficient mice

Lysophosphatidic acid (LPA) is a natural lysophospholipid present at high concentrations within lipid-rich atherosclerotic plaques. Upon local accumulation in the damaged vessels, LPA can act as a potent activator for various types of immune cells through its specific membrane receptors LPA1/3. LPA elicits chemotactic, pro-inflammatory and apoptotic effects that lead to atherosclerotic plaque progression. In this study we aimed to inhibit LPA signaling by means of LPA1/3 antagonism using the small molecule Ki16425. We show that LPA1/3 inhibition significantly impaired atherosclerosis progression. Treatment with Ki16425 also resulted in reduced CCL2 production and secretion, which led to less monocyte and neutrophil infiltration. Furthermore, we provide evidence that LPA1/3 blockade enhanced the percentage of non-inflammatory, Ly6Clow monocytes and CD4+ CD25+ FoxP3+ T-regulatory cells. Finally, we demonstrate that LPA1/3 antagonism mildly reduced plasma LDL cholesterol levels. Therefore, pharmacological inhibition of LPA1/3 receptors may prove a promising approach to diminish atherosclerosis development.Biopharmaceutic

Flow Cytometry-Based Characterization of Mast Cells in Human Atherosclerosis

The presence of mast cells in human atherosclerotic plaques has been associated with adverse cardiovascular events. Mast cell activation, through the classical antigen sensitized-IgE binding to their characteristic Fcε-receptor, causes the release of their cytoplasmic granules. These granules are filled with neutral proteases such as tryptase, but also with histamine and pro-inflammatory mediators. Mast cells accumulate in high numbers within human atherosclerotic tissue, particularly in the shoulder region of the plaque. These findings are largely based on immunohistochemistry, which does not allow for the extensive characterization of these mast cells and of the local mast cell activation mechanisms. In this study, we thus aimed to develop a new flow-cytometry based methodology in order to analyze mast cells in human atherosclerosis. We enzymatically digested 22 human plaque samples, collected after femoral and carotid endarterectomy surgery, after which we prepared a single cell suspension for flow cytometry. We were able to identify a specific mast cell population expressing both CD117 and the FcεR, and observed that most of the intraplaque mast cells were activated based on their CD63 protein expression. Furthermore, most of the activated mast cells had IgE fragments bound on their surface, while another fraction showed IgE-independent activation. In conclusion, we are able to distinguish a clear mast cell population in human atherosclerotic plaques, and this study establishes a strong relationship between the presence of IgE and the activation of mast cells in advanced atherosclerosis. Our data pave the way for potential therapeutic intervention through targeting IgE-mediated actions in human atherosclerosis.Biopharmaceutic

Fruit and vegetable intake and prostate cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC)

Several dietary factors have been studied in relation to prostate cancer; however, most studies have not reported on subtypes of fruit and vegetables or tumor characteristics, and results obtained so far are inconclusive. This study aimed to examine the prospective association of total and subtypes of fruit and vegetable intake with the incidence of prostate cancer overall, by grade and stage of disease, and prostate cancer death. Lifestyle information for 142,239 men participating in the European Prospective Investigation into Cancer and Nutrition from 8 European countries was collected at baseline. Multivariable Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). After an average follow-up time of 13.9 years, 7,036 prostate cancer cases were identified. Compared with the lowest fifth, those in the highest fifth of total fruit intake had a significantly reduced prostate cancer risk (HR = 0.91; 95% CI = 0.83–0.99; p-trend = 0.01). No associations between fruit subtypes and prostate cancer risk were observed, except for citrus fruits, where a significant trend was found (HR = 0.94; 95% CI = 0.86–1.02; p-trend = 0.01). No associations between total and subtypes of vegetables and prostate cancer risk were observed. We found no evidence of heterogeneity in these associations by tumor grade and stage, with the exception of significant heterogeneity by tumor grade (pheterogeneity<0.001) for leafy vegetables. No significant associations with prostate cancer death were observed. The main finding of this prospective study was that a higher fruit intake was associated with a small reduction in prostate cancer risk. Whether this association is causal remains unclear

CD8+ T-cells contribute to lesion stabilization in advanced atherosclerosis by limiting macrophage content and CD4+ T-cell responses

Human endarterectomy samples analyzed by flow cytometry showed a negative correlation between the percentage of CD8+ T-cells and macrophages, suggesting a possible protective role for these cells in lesion development. To further test this hypothesis, LDLr-/- mice were fed a Western-type diet (WTD) for 10 weeks to induce atherosclerosis, after which they received CD8α-depleting or isotype control antibody for six weeks. Depletion of CD8+ T-cells in advanced atherosclerosis resulted in less stable lesions, with significantly reduced collagen content in the trivalve area, increased macrophage content and increased necrotic core area compared to controls. Mechanistically, we observed that CD8 depletion specifically increased the fraction of Th1 CD4+ T-cells in the lesions. Treatment of WTD-fed LDLr-/- mice with a FasL-neutralizing antibody resulted in similar changes in macrophages and CD4+ T-cell skewing as CD8+ T-cell depletion. T lymphocytes play an important role in atherosclerosis development, but the role of the CD8+ T-cell remains debated, especially in the clinically relevant advanced stages of atherosclerosis development. Here, we set out to determine the role of CD8+ T-cells in advanced atherosclerosis. These findings demonstrate for the first time a local, protective role for CD8+ T-cells in advanced atherosclerosis, through limiting accumulation of Th1 cells and macrophages, identifying a novel regulatory mechanism for these cells in atherosclerosis. Methods and Results Aims ConclusionDrug Delivery Technolog

Serum endotoxins and flagellin and risk of colorectal cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC) Cohort

Background: Chronic inflammation and oxidative stress are thought to be involved in colorectal cancer development. These processes may contribute to leakage of bacterial products, such as lipopolysaccharide (LPS) and flagellin, across the gut barrier. The objective of this study, nested within a prospective cohort, was to examine associations between circulating LPS and flagellin serum antibody levels and colorectal cancer risk. Methods: A total of 1,065 incident colorectal cancer cases (colon, n = 667; rectal, n = 398) were matched (1:1) to control subjects. Serum flagellin- and LPS-specific IgA and IgG levels were quantitated by ELISA. Multivariable conditional logistic regression models were used to calculate ORs and 95% confidence intervals (CI), adjusting for multiple relevant confouding factors. Results: Overall, elevated anti-LPS and anti-flagellin biomarker levels were not associated with colorectal cancer risk. After testing potential interactions by various factors relevant for colorectal cancer risk and anti-LPS and anti-flagellin, sex was identified as a statistically significant interaction factor (Pinteraction < 0.05 for all the biomarkers). Analyses stratified by sex showed a statistically significant positive colorectal cancer risk association for men (fully-adjusted OR for highest vs. lowest quartile for total anti-LPS + flagellin, 1.66; 95% CI, 1.10–2.51; Ptrend, 0.049), whereas a borderline statistically significant inverse association was observed for women (fully-adjusted OR, 0.70; 95% CI, 0.47–1.02; Ptrend, 0.18). Conclusion: In this prospective study on European populations, we found bacterial exposure levels to be positively associated to colorectal cancer risk among men, whereas in women, a possible inverse association may exist. Impact: Further studies are warranted to better clarify these preliminary observations

A Conserved Role for SNX9-Family Members in the Regulation of Phagosome Maturation during Engulfment of Apoptotic Cells

Clearance of apoptotic cells is of key importance during development, tissue homeostasis and wound healing in multi-cellular animals. Genetic studies in the nematode Caenorhabditis elegans have identified a set of genes involved in the early steps of cell clearance, in particular the recognition and internalization of apoptotic cells. A pathway that orchestrates the maturation of phagosomes containing ingested apoptotic cells in the worm has recently been described. However, many steps in this pathway remain elusive. Here we show that the C. elegans SNX9-family member LST-4 (lateral signaling target) and its closest mammalian orthologue SNX33 play an evolutionary conserved role during apoptotic cell corpse clearance. In lst-4 deficient worms, internalized apoptotic cells accumulated within non-acidified, DYN-1-positive but RAB-5-negative phagosomes. Genetically, we show that LST-4 functions at the same step as DYN-1 during corpse removal, upstream of the GTPase RAB-5. We further show that mammalian SNX33 rescue C. elegans lst-4 mutants and that overexpression of truncated SNX33 fragments interfered with phagosome maturation in a mammalian cell system. Taken together, our genetic and cell biological analyses suggest that LST-4 is recruited through a combined activity of DYN-1 and VPS-34 to the early phagosome membrane, where it cooperates with DYN-1 to promote recruitment/retention of RAB-5 on the early phagosomal membrane during cell corpse clearance. The functional conservation between LST-4 and SNX33 indicate that these early steps of apoptotic phagosome maturation are likely conserved through evolution

Coffee, tea and melanoma risk: findings from the European Prospective Investigation into Cancer and Nutrition

In vitro and animal studies suggest that bioactive constituents of coffee and tea may have anticarcinogenic effects against cutaneous melanoma, however epidemiological evidence is limited to date. We examined the relationships between coffee (total, caffeinated or decaffeinated) and tea consumption and risk of melanoma in the European Prospective Investigation into Cancer and Nutrition (EPIC). EPIC is a multi-centre prospective study that enrolled over 500,000 participants aged 25-70 years from ten European countries in 1992-2000. Information on coffee and tea drinking was collected at baseline using validated country-specific dietary questionnaires. We used adjusted Cox proportional hazards regression models to calculate hazard ratios (HR) and 95% confidence intervals (95% CI) for the associations between coffee and tea consumption and melanoma risk. Overall, 2,712 melanoma cases were identified during a median follow-up of 14.9 years among 476,160 study participants. Consumption of caffeinated coffee was inversely associated with melanoma risk among men (HR for highest quartile of consumption vs. non-consumers 0.31, 95% CI 0.14-0.69) but not among women (HR 0.96, 95% CI 0.62-1.47). There were no statistically significant associations between consumption of decaffeinated coffee or tea and the risk of melanoma among both men and women. The consumption of caffeinated coffee was inversely associated with melanoma risk among men in this large cohort study. Further investigations are warranted to confirm our findings and clarify the possible role of caffeine and other coffee compounds in reducing the risk of melanoma.In France, the E3N study was financially supported by the Mutuelle Générale de l'Education Nationale (MGEN), the European Community, the French League Against Cancer (LNCC); Gustave Roussy; and the French Institute of Health and Medical research (INSERM). EPIC-Greece was supported by the Hellenic Health Foundation. Support for EPIC Norfolk is from Medical Research Council UK and Cancer Research UK. EPIC-Italy was supported by the Italian Association for Cancer Research (AIRC)