Short-term LPS induces aortic valve thickening in ApoE*3Leiden mice.

BACKGROUND: Recently, it was shown that 12 weeks of lipopolysaccharide (LPS) administration to nonatherosclerotic mice induced thickening of the aortic heart valve (AV). Whether such effects may also occur even earlier is unknown. As most patients with AV stenosis also have atherosclerosis, we studied the short-term effect of LPS on the AVs in an atherosclerotic mouse model. METHODS: ApoE*3Leiden mice, on an atherogenic diet, were injected intraperitoneally with either LPS or phosphate buffered saline (PBS), and sacrificed 2 or 15 days later. AVs were assessed for size, fibrosis, glycosaminoglycans (GAGs), lipids, calcium deposits, iron deposits and inflammatory cells. RESULTS: LPS injection caused an increase in maximal leaflet thickness at 2 days (128.4 µm) compared to PBS-injected mice (67.8 µm; P = 0.007), whereas at 15 days this was not significantly different. LPS injection did not significantly affect average AV thickness on day 2 (37.8 µm), but did significantly increase average AV thickness at day 15 (41.6 µm; P = 0.038) compared to PBS-injected mice (31.7 and 32.3 µm respectively). LPS injection did not affect AV fibrosis, GAGs and lipid content. Furthermore, no calcium deposits were found. Iron deposits, indicative for valve haemorrhage, were observed in one AV of the PBS-injected group (a day 2 mouse; 9.1%) and in five AVs of the LPS-injected group (both day 2- and 15 mice; 29.4%). No significant differences in inflammatory cell infiltration were observed upon LPS injection. CONCLUSION: Short-term LPS apparently has the potential to increase AV thickening and haemorrhage. These results suggest that systemic inflammation can acutely compromise AV structure.

Prevention of age-induced N(ε)-(carboxymethyl)lysine accumulation in the microvasculature.

OBJECTIVE: N(ε)-(carboxymethyl)lysine (CML) is one of the major advanced glycation end products in both diabetics and nondiabetics. CML depositions in the microvasculature have recently been linked to the aetiology of acute myocardial infarction and cognitive impairment in Alzheimer's disease, possibly related to local enhancement of inflammation and oxidative processes. We hypothesized that CML deposition in the microvasculature of the heart and brain is age-induced and that it could be inhibited by a diet intervention with docosahexaenoic acid (DHA), an omega-3 fatty acid known for its anti-inflammatory and antioxidative actions. MATERIALS AND METHODS: ApoE(-/-) mice (n = 50) were fed a Western diet and were sacrificed after 40, 70 and 90 weeks. Part of these mice (n = 20) were fed a Western diet enriched with DHA from 40 weeks on. CML in cardiac and cerebral microvessels was quantified using immunohistochemistry. RESULTS: Cardiac microvascular depositions of CML significantly increased with an immunohistochemical score of 11·85 [5·92-14·60] at 40 weeks, to 33·17 [17·60-47·15] at 70 weeks (P = 0·005). At the same time points, cerebral microvascular CML increased from 6·45; [4·78-7·30] to 12·99; [9·85-20·122] (P = 0·003). DHA decreased CML in the intramyocardial vasculature at both 70 and 90 weeks, significant at 70 weeks [33·17; (17·60-47·15) vs. 14·73; (4·44-28·16) P = 0·037]. No such effects were found in the brain. CONCLUSIONS: Accumulation of N(ε)-(carboxymethyl)lysine in the cerebral and cardiac microvasculature is age-induced and is prevented by DHA in the intramyocardial vessels of ApoE(-/-) mice.

Immunosuppressive drug azathioprine reduces aneurysm progression through inhibition of Rac1 and c-Jun-terminal-N-kinase in endothelial cells.

OBJECTIVE: In aortic aneurysms the arterial vessel wall is dilated because of destruction of its integrity, which may lead to lethal vessel rupture. Chronic infiltration of inflammatory cells into the vessel wall is fundamental to aneurysm pathology. We aim to limit aneurysm growth by inhibition of inflammation and reducing endothelial cell (EC) activation with immunosuppressive drug azathioprine (Aza). APPROACH AND RESULTS: Aza and its metabolite 6-mercaptopurine have anti-inflammatory effects on leukocytes. We here demonstrate that treatment of ECs with 6-mercaptopurine inhibits cell activation as illustrated by reduced expression of interleukin-12, CCL5, CCL2, and vascular cell adhesion molecule-1 and inhibition of monocyte-EC adhesion. The underlying mechanism of 6-mercaptopurine involves suppression of GTPase Rac1 activation, resulting in reduced phosphorylation of c-Jun-terminal-N-kinase and c-Jun. Subsequently, the effect of Aza was investigated in aneurysm formation in the angiotensin II aneurysm mouse model in apolipoprotein E-deficient mice. We demonstrated that Aza decreases de novo aortic aneurysm formation from an average aneurysm severity score of 2.1 (control group) to 0.6 (Aza group), and that Aza effectively delays aorta pathology in a progression experiment, resulting in a reduced severity score from 2.8 to 1.7 in Aza-treated mice. In line with the in vitro observations, Aza-treated mice showed less c-Jun-terminal-N-kinase activation in ECs and reduced leukocyte influx in the aortic wall. CONCLUSIONS: The immunosuppressive drug Aza has an anti-inflammatory effect and in ECs inhibits Rac1 and c-Jun-terminal-N-kinase activation, which may explain the protective effect of Aza in aneurysm development and, most importantly for clinical implications, aneurysm severity.

The Effect of Years-Long Exposure to Low-Dose Colchicine on Renal and Liver Function and Blood Creatine Kinase Levels: Safety Insights from the Low-Dose Colchicine 2 (LoDoCo2) Trial.

BACKGROUND AND OBJECTIVE: The Low-Dose Colchicine-2 (LoDoCo2) trial showed that 2-4 years exposure to colchicine 0.5 mg once daily reduced the risk of cardiovascular events in patients with chronic coronary artery disease. The potential effect of years-long exposure to colchicine on renal or liver function and creatine kinase (CK) has not been systematically evaluated and was investigated in this LoDoCo2 substudy. METHODS: Blood samples drawn from 1776 participants at the close-out visit of the LoDoCo2 trial were used to measure markers of renal function (creatinine, blood urea nitrogen [BUN]), liver function (alanine aminotransferase [ALT], γ-glutamyl transferase [GGT], bilirubin and albumin), and CK. Renal and liver function as well as hyperCKemia (elevated CK) were categorized to the degree of elevation biomarkers as mild, mild/moderate, moderate/severe, and marked elevations. RESULTS: In total, 1776 participants (mean age 66.5 years, 72% male) contributed to this analysis, with a median exposure to trial medication of 32.7 months. Compared with placebo, colchicine was not associated with changes in creatinine and BUN but was associated with elevations in ALT (30 U/L vs. 26 U/L; p < 0.01) and CK (123 U/L vs. 110 U/L; p < 0.01). Most elevations in ALT and CK were mild in both treatment groups. There were no moderate to marked ALT elevations (> 5-10 × upper limit of normal [ULN]) in both treatment groups, and 6 (0.7%) colchicine-treated vs. 2 (0.2%) placebo-treated participants had moderate to marked CK elevations (> 5-10 × ULN). CONCLUSION: In chronic coronary artery disease, 2-4 years of exposure to colchicine 0.5 mg once daily was associated with small elevations in ALT and CK, but was not associated with changes in renal function. TRIAL REGISTRATION: https://www.anzctr.org.au ; ACTRN12614000093684, 24 January 2014.

Colchicine in Patients With Chronic Coronary Disease in Relation to Prior Acute Coronary Syndrome.

BACKGROUND: Colchicine reduces risk of cardiovascular events in patients post-myocardial infarction and in patients with chronic coronary disease. It remains unclear whether this effect is related to the time of onset of treatment following an acute coronary syndrome (ACS). OBJECTIVES: This study investigates risk for major adverse cardiovascular events in relation to history and timing of prior ACS, to determine whether the benefits of colchicine are consistent independent of prior ACS status. METHODS: The LoDoCo2 (Low-Dose Colchicine 2) trial randomly allocated patients with chronic coronary disease to colchicine 0.5 mg once daily or placebo. The rate of the composite of cardiovascular death, spontaneous myocardial infarction, ischemic stroke, or ischemia-driven coronary revascularization was compared between patients with no prior, recent (6-24 months), remote (2-7 years), or very remote (>7 years) ACS; interaction between ACS status and colchicine treatment effect was assessed. RESULTS: In 5,522 randomized patients, risk of the primary endpoint was independent of prior ACS status. Colchicine consistently reduced the primary endpoint in patients with no prior ACS (incidence: 2.8 vs 3.4 events per 100 person-years; hazard ratio [HR]: 0.81; 95% confidence interval [CI]: 0.52-1.27), recent ACS (incidence: 2.4 vs 3.3 events per 100 person-years; HR: 0.75; 95% CI: 0.51-1.10), remote ACS (incidence: 1.8 vs 3.2 events per 100 person-years, HR: 0.55; 95% CI: 0.37-0.82), and very remote ACS (incidence: 3.0 vs 4.3 events per 100 person-years, HR: 0.70; 95% CI: 0.51-0.96) (P for interaction = 0.59). CONCLUSIONS: The benefits of colchicine are consistent irrespective of history and timing of prior ACS. (The LoDoCo2 Trial: Low Dose Colchicine for secondary prevention of cardiovascular disease [LoDoCo2] ACTRN12614000093684).