Neutrophil cannibalism – a back up when the macrophage clearance system is insufficient

BACKGROUND: During a lipopolysaccharide-induced lung inflammation, a massive accumulation of neutrophils occurs, which is normally cleared by macrophage phagocytosis following neutrophil apoptosis. However, in cases of extensive apoptosis the normal clearance system may fail, resulting in extensive neutrophil secondary necrosis. The aim of this study was to explore the hypothesis that neutrophils, in areas of the lung with extensive cellular infiltration, contribute to clearance by phagocytosing apoptotic cells and/or cell debris derived from secondary necrosis. METHODS: Intranasal lipopolysaccharide administration was used to induce lung inflammation in mice. The animals were sacrificed at seven time points following administration, bronchoalveolar lavage was performed and tissue samples obtained. Electron microscopy and histochemistry was used to assess neutrophil phagocytosis. RESULTS: Electron microscopic studies revealed that phagocytosing neutrophils was common, at 24 h after LPS administration almost 50% of the total number of neutrophils contained phagosomes, and the engulfed material was mainly derived from other neutrophils. Histochemistry on bronchoalvolar lavage cells further showed phagocytosing neutrophils to be frequently occurring. CONCLUSION: Neutrophils are previously known to phagocytose invading pathogens and harmful particles. However, this study demonstrates that neutrophils are also able to engulf apoptotic neutrophils or cell debris resulting from secondary necrosis of neutrophils. Neutrophils may thereby contribute to clearance and resolution of inflammation, thus acting as a back up system in situations when the macrophage clearance system is insufficient and/or overwhelmed

The Effect of Aggressive Versus Conventional Lipid-lowering Therapy on Markers of Inflammatory and Oxidative Stress

Purpose Recent trial results are in favor of aggressive lipid lowering using high dose statins in patients needing secondary prevention. It is unclear whether these effects are solely due to more extensive lipid lowering or the result of the potentially anti-inflammatory properties of statins. We aimed to determine whether aggressive compared with conventional statin therapy is more effective in reducing systemic markers of inflammation and oxidative stress. Materials and methods This was a multi-centre, double-blind, placebo-controlled trial. Patients with previous cardiovascular disease, who did not achieve low density lipoprotein (LDL) cholesterol levels <2.6 mmol/l on conventional statin therapy (simvastatin 40 mg) were randomized to continue with simvastatin 40 mg or to receive atorvastatin 40 mg for 8 weeks and thereafter atorvastatin 80 mg for the final 8 weeks (aggressive treatment). Lipids, C-reactive protein, soluble cellular adhesion molecules, neopterin, von Willebrand Factor, and antibodies against oxidized LDL were measured at baseline and after 16 weeks. Results Lipid levels decreased significantly in the aggressive treatment group (LDL-C reduction 20.8%; P <0.001), whereas a slight increase was observed in the conventional group (LDL-C increase 3.7%; P = 0.037). A significant reduction in antibodies against oxidized LDL was seen in the aggressive (13.4%; P <0.001) and the conventional (26.8%; P <0.001) group, but there was no difference between groups (P = 0.25). Furthermore, no significant differences in change in other biomarkers was observed between both groups. Conclusions This study does not support the hypothesis that a more profound reduction in inflammatory and oxidative stress contributes to the benefits of aggressive statin therapy

Effect of rosuvastatin on insulin sensitivity in patients with familial combined hyperlipidaemia.

Contains fulltext : 48014.pdf (publisher's version ) (Closed access)BACKGROUND: By influencing the mevalonate pathway, statins may have multiple effects besides lipid lowering. This study was designed to evaluate the effect of rosuvastatin on serum lipids and insulin sensitivity in nondiabetic subjects with familial combined hyperlipidaemia (FCH), a population characterized by decreased insulin sensitivity. METHODS: In a double-blind randomized crossover study, 18 subjects with FCH (without evident cardiovascular disease, mean age 54 +/- 7 years) were randomized to rosuvastatin 40 mg day(-1) or placebo for 12 weeks. Blood samples were taken at baseline and after 4, 8 and 12 weeks of both treatment periods. Insulin sensitivity was determined with euglycaemic-hyperinsulinaemic clamp after 12 weeks of both treatment periods. RESULTS: Serum lipids and lipoproteins improved significantly. Mean total cholesterol after the rosuvastatin treatment period was 44% lower compared to the placebo treatment period (triglycerides -28%; LDL-c -50%; VLDL-c -56%, VLDL-TG -39%) and both parameters of low-grade inflammation (as measured by hsCRP, -16%) and oxidative stress (as measured by plasma-oxLDL, -55%) decreased markedly after rosuvastatin therapy as compared to placebo. However, the insulin sensitivity index was unchanged (41.7 +/- 17.4 vs. 40.6 +/- 11.1 L kg(-1) min(-1), placebo vs. rosuvastatin, P = 0.71). CONCLUSION: Despite marked improvements in lipid and lipoprotein values, low-grade inflammation and oxidative stress, a relatively high dose of rosuvastatin did not change insulin sensitivity in subjects with FCH