A novel role for bioactive lipids in stem cell mobilization during cardiac ischemia: new paradigms in thrombosis: novel mediators and biomarkers

Neutrophils in cardiovascular disease: warmongers, peacemakers, or both?

Neutrophils, the most abundant of all leucocytes and the first cells to arrive at the sites of sterile inflammation/injury act as a double-edged sword. On one hand, they inflict a significant collateral damage to the tissues and on the other hand, they help facilitate wound healing by a number of mechanisms. Recent studies have drastically changed the perception of neutrophils from being simple one-dimensional cells with an unrestrained mode of action to a cell type that display maturity and complex behaviour. It is now recognized that neutrophils are transcriptionally active and respond to plethora of signals by deploying a wide variety of cargo to influence the activity of other cells in the vicinity. Neutrophils can regulate macrophage behaviour, display innate immune memory, and play a major role in the resolution of inflammation in a context-dependent manner. In this review, we provide an update on the factors that regulate neutrophil production and the emerging dichotomous role of neutrophils in the context of cardiovascular diseases, particularly in atherosclerosis and the ensuing complications, myocardial infarction, and heart failure. Deciphering the complex behaviour of neutrophils during inflammation and resolution may provide novel insights and in turn facilitate the development of potential therapeutic strategies to manage cardiovascular disease.

Prokaryotic and Mitochondrial Lipids: A Survey of Evolutionary Origins

Mitochondria and bacteria share a myriad of properties since it is believed that the powerhouses of the eukaryotic cell have evolved from a prokaryotic origin. Ribosomal RNA sequences, DNA architecture and metabolism are strikingly similar in these two entities. Proteins and nucleic acids have been a hallmark for comparison between mitochondria and prokaryotes. In this chapter, similarities (and differences) between mitochondrial and prokaryotic membranes are addressed with a focus on structure-function relationship of different lipid classes. In order to be suitable for the theme of the book, a special emphasis is reserved to the effects of bioactive sphingolipids, mainly ceramide, on mitochondrial membranes and their roles in initiating programmed cell death.

Sphingolipids in neurodegeneration (with focus on ceramide and S1P)

For many decades, research on sphingolipids associated with neurodegenerative disease focused on alterations in glycosphingolipids, particularly glycosylceramides (cerebrosides), sulfatides, and gangliosides. This seemed quite natural since many of these glycolipids are constituents of myelin and accumulated in lipid storage diseases (sphingolipidoses) resulting from enzyme deficiencies in glycolipid metabolism. With the advent of recognizing ceramide and its derivative, sphingosine-1-phosphate (S1P), as key players in lipid cell signaling and regulation of cell death and survival, research focus shifted toward these two sphingolipids. Ceramide and S1P are invoked in a plethora of cell biological processes participating in neurodegeneration such as ER stress, autophagy, dysregulation of protein and lipid transport, exosome secretion and neurotoxic protein spreading, neuroinflammation, and mitochondrial dysfunction. Hence, it is timely to discuss various functions of ceramide and S1P in neurodegenerative disease and to define sphingolipid metabolism and cell signaling pathways as potential targets for therapy.

FTY720 elevates smooth muscle contraction of aorta and blood pressure in rats via ERK activation

Sphingosine 1‐phosphate (S1P) is an important signaling sphingolipid involved in the pathogenesis of various cardio cerebral vascular diseases such as ischemic stroke. In particular, the S1P mimetic FTY720 is protective for brain against ischemic conditions. However, whether and how FTY720 can modulate vascular tone and blood pressure remains to be determined. We showed that FTY720 (1 mg/kg) enhanced the contractile response of rat thoracic aortic rings induced by high potassium and phenylephrine, respectively. This enhancement involves the activation of extracellular signal‐regulated kinase (ERK) since ERK phosphorylation was also enhanced and application of PD98059 (10 μmol/L), an inhibitor of ERK activation abrogated the aforementioned enhanced response by FTY720. In parallel, FTY720 (1 mg/kg) led to a modest elevation of blood pressure in rats, effects also being prevented by PD98059. In contrast, FTY720 decreased the high potassium‐induced contractile response in basilarartery preparations from rabbits, an effect blocked by PD98059. Together, FTY720‐induced an enhanced response of artery contractility in aorta and in arterial pressure involving ERK activation, with an attenuation in basilarartery contractility. This action property of FTY720 would be endowed with a potential of facilitating more blood flow perfusion to the brain and improving blood supply to the ischemic brain region and could be useful as an adjuvant in the treatment of ischemic stroke in the clinics.