Pinealectomy and melatonin administration in rats: their effects on pulmonary edema induced by α-naphthylthiourea

We aimed to observe the possible effects of melatonin (MLT) deprivation (pinealectomy) and exogenous MLT administration on pulmonary edema induced by alpha-naphthylthiourea (ANTU), a toxic chemical agent, in rats. Seventy animals were assigned to seven groups: control, sham pinealectomy (PINX), PINX, ANTU (10 mg/kg intraperitoneal on day 30), ANTU + MLT (10 mg/kg/day i.p. for 30 days), ANTU + PINX, and ANTU + PINX + MLT.In this study, pleural effusion (PE) formation, lung weight/body weight (LW/BW) and PE/BW ratios (fluid accumulation and weight values in the lungs) increase detected. Pre-ANTU MLT administration led to significant decreases in PE, LW/BW, and PE/BW levels. The inhibited glutathione (GSH) and superoxide dismutase (SOD) levels and high malondialdehyde (MDA) levels that ANTU increase lipid peroxidation in the study. MLT administration eliminated oxidative stress by reducing MDA and ameliorating GSH and SOD levels.Pre-ANTU MLT administration led to a significant decrease in interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) levels in the lung when compared to the ANTU group without MLT administration. Post-pinealectomy ANTU administration significantly increased IL-1β and TNF-α levels when compared to ANTU and MLT administration without pinealectomy. Diffused inflammatory cell infiltration, interstitial pulmonary edema, and histopathological congestion were observed after the administration of ANTU. Severity of the damage was elevated in the ANTU + PINX group. MLT treatment regressed pulmonary effusion and edema and improves lung structure. In brief, the findings suggested that MLT inhibited proinflammatory mediators and could serve as a therapeutic agent to prevent inflammatory disorders.

The Role of Obesity, Inflammation and Sphingolipids in the Development of an Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a local dilatation of the vessel equal to or exceeding 3 cm. It is a disease with a long preclinical period commonly without any symptoms in its initial stage. Undiagnosed for years, aneurysm often leads to death due to vessel rupture. The basis of AAA pathogenesis is inflammation, which is often associated with the excess of adipose tissue, especially perivascular adipose tissue, which synthesizes adipocytokines that exert a significant influence on the formation of aneurysms. Pro-inflammatory cytokines such as resistin, leptin, and TNFα have been shown to induce changes leading to the formation of aneurysms, while adiponectin is the only known compound that is secreted by adipose tissue and limits the development of aneurysms. However, in obesity, adiponectin levels decline. Moreover, inflammation is associated with an increase in the amount of macrophages infiltrating adipose tissue, which are the source of matrix metalloproteinases (MMP) involved in the degradation of the extracellular matrix, which are an important factor in the formation of aneurysms. In addition, an excess of body fat is associated with altered sphingolipid metabolism. It has been shown that among sphingolipids, there are compounds that play an opposite role in the cell: ceramide is a pro-apoptotic compound that mediates the development of inflammation, while sphingosine-1-phosphate exerts pro-proliferative and anti-inflammatory effects. It has been shown that the increase in the level of ceramide is associated with a decrease in the concentration of adiponectin, an increase in the concentration of TNFα, MMP-9 and reactive oxygen species (which contribute to the apoptosis of vascular smooth muscle cell). The available data indicate a potential relationship between obesity, inflammation and disturbed sphingolipid metabolism with the formation of aneurysms; therefore, the aim of this study was to systematize the current knowledge on the role of these factors in the pathogenesis of abdominal aortic aneurysm.

Sphingosine-1-phosphate in acute exercise and training

Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid found in all eukaryotic cells. Although it may function as an intracellular second messenger, most of its effects are induced extracellularly via activation of a family of five specific membrane receptors. Sphingosine-1-phosphate is enriched in plasma, where it is transported by high-density lipoprotein and albumin, as well as in erythrocytes and platelets which store and release large amounts of this sphingolipid. Sphingosine-1-phosphate regulates a host of cellular processes such as growth, proliferation, differentiation, migration, and apoptosis suppression. It was also shown to play an important role in skeletal muscle physiology and pathophysiology. In recent years, S1P metabolism in both muscle and blood was found to be modulated by exercise. In this review, we summarize the current knowledge on the effect of acute exercise and training on S1P metabolism, highlighting the role of this sphingolipid in skeletal muscle adaptation to physical effort.

Sphingosine 1-phosphate: Lipid signaling in pathology and therapy

Sphingosine 1-phosphate (S1P), a metabolic product of cell membrane sphingolipids, is bound to extracellular chaperones, is enriched in circulatory fluids, and binds to G protein-coupled S1P receptors (S1PRs) to regulate embryonic development, postnatal organ function, and disease. S1PRs regulate essential processes such as adaptive immune cell trafficking, vascular development, and homeostasis. Moreover, S1PR signaling is a driver of multiple diseases. The past decade has witnessed an exponential growth in this field, in part because of multidisciplinary research focused on this lipid mediator and the application of S1PR-targeted drugs in clinical medicine. This has revealed fundamental principles of lysophospholipid mediator signaling that not only clarify the complex and wide ranging actions of S1P but also guide the development of therapeutics and translational directions in immunological, cardiovascular, neurological, inflammatory, and fibrotic diseases.

Sphingosine kinase and sphingosine-1-phosphate receptor signaling pathway in inflammatory gastrointestinal disease and cancers: A novel therapeutic target

Inflammatory gastrointestinal (GI) diseases and malignancies are associated with growing morbidity and cancer-related mortality worldwide. GI tumor and inflammatory cells contain activated sphingolipid-metabolizing enzymes, including sphingosine kinase 1 (SphK1) and SphK2, that generate sphingosine-1-phosphate (S1P), a highly bioactive compound. Many inflammatory responses, including lymphocyte trafficking, are directed by circulatory S1P, present in high concentrations in both the plasma and the lymph of cancer patients. High fat and sugar diet, disbalanced intestinal flora, and obesity have recently been linked to activation of inflammation and SphK/S1P/S1P receptor (S1PR) signaling in various GI pathologies, including cancer. SphK1 overexpression and activation facilitate and enhance the development and progression of esophageal, gastric, and colon cancers. SphK/S1P axis, a mediator of inflammation in the tumor microenvironment, has recently been defined as a target for the treatment of GI disease states, including inflammatory bowel disease and colitis. Several SphK1 inhibitors and S1PR antagonists have been developed as novel anti-inflammatory and anticancer agents. In this review, we analyze the mechanisms of SphK/S1P signaling in GI tissues and critically appraise recent studies on the role of SphK/S1P/S1PR in inflammatory GI disorders and cancers. The potential role of SphK/S1PR inhibitors in the prevention and treatment of inflammation-mediated GI diseases, including GI cancer, is also evaluated.