The Mucus of Actinia equina (Anthozoa, Cnidaria): An Unexplored Resource for Potential Applicative Purposes

The mucus produced by many marine organisms is a complex mixture of proteins and polysaccharides forming a weak watery gel. It is essential for vital processes including locomotion, navigation, structural support, heterotrophic feeding and defence against a multitude of environmental stresses, predators, parasites, and pathogens. In the present study we focused on mucus produced by a benthic cnidarian, the sea anemone Actinia equina (Linnaeus, 1758) for preventing burial by excess sedimentation and for protection. We investigated some of the physico-chemical properties of this matrix such as viscosity, osmolarity, electrical conductivity, protein, carbohydrate, and total lipid contents. Some biological activities such as hemolytic, cytotoxic, and antibacterial lysozyme-like activities were also studied. The A. equina mucus is mainly composed by water (96.2% ± 0.3%), whereas its dry weight is made of 24.2% ± 1.3% proteins and 7.8% ± 0.2% carbohydrates, with the smallest and largest components referable to lipids (0.9%) and inorganic matter (67.1%). The A. equina mucus matrix exhibited hemolytic activity on rabbit erythrocytes, cytotoxic activity against the tumor cell line K562 (human erythromyeloblastoid leukemia) and antibacterial lysozyme-like activity. The findings from this study improve the available information on the mucus composition in invertebrates and have implications for future investigations related to exploitation of A. equina and other sea anemones’ mucus as a source of bioactive compounds of high pharmaceutical and biotechnological interest

Deficiency of AMPKα1 Exacerbates Intestinal Injury and Remote Acute Lung Injury in Mesenteric Ischemia and Reperfusion in Mice

Mesenteric ischemia and reperfusion (I/R) injury can ensue from a variety of vascular diseases and represents a major cause of morbidity and mortality in intensive care units. It causes an inflammatory response associated with local gut dysfunction and remote organ injury. Adenosine monophosphate-activated protein kinase (AMPK) is a crucial regulator of metabolic homeostasis. The catalytic α1 subunit is highly expressed in the intestine and vascular system. In loss-of-function studies, we investigated the biological role of AMPKα1 in affecting the gastrointestinal barrier function. Male knock-out (KO) mice with a systemic deficiency of AMPKα1 and wild-type (WT) mice were subjected to a 30 min occlusion of the superior mesenteric artery. Four hours after reperfusion, AMPKα1 KO mice exhibited exaggerated histological gut injury and impairment of intestinal permeability associated with marked tissue lipid peroxidation and a lower apical expression of the junction proteins occludin and E-cadherin when compared to WT mice. Lung injury with neutrophil sequestration was higher in AMPKα1 KO mice than WT mice and paralleled with higher plasma levels of syndecan-1, a biomarker of endothelial injury. Thus, the data demonstrate that AMPKα1 is an important requisite for epithelial and endothelial integrity and has a protective role in remote organ injury after acute ischemic events

Peroxisome proliferator activated receptor γ is not necessary for the development of LPS-induced tolerance in macrophages

Peroxisome proliferator activated receptor-γ (PPARγ) has been reported to exert anti-inflammatory properties in endotoxic shock and sepsis. One phenomenon that alters the inflammatory response to endotoxin [lipopolysaccharide (LPS)] is endotoxin tolerance, which is caused by previous exposure to endotoxin. Here, we investigate whether changes in endogenous PPARγ function regulate this phenomenon using three different models of LPS-induced tolerance in macrophages. In a first in vitro model, previous LPS exposure of murine J774.2 macrophages suppressed tumour necrosis factor-α (TNF-α) release in response to subsequent LPS challenge. Treatment of J774.2 cells with the PPARγ inhibitor GW9662 did not alter tolerance induction because these cells were still hyporesponsive to the secondary LPS challenge. In a second ex vivo model, primary rat peritoneal macrophages from LPS-primed rats exhibited suppression of thromboxane B2 and TNF-α production, while maintaining nitrite production in response to in vitro LPS challenge. Pretreatment of rats with the PPARγ inhibitor GW9662 in vivo failed to alter the tolerant phenotype of these primary macrophages. In a third ex vivo model, primary peritoneal macrophages with conditional deletion of PPARγ were harvested from LPS-primed Cre-lox mice (Cre+/+ PPARγ−/−) and exhibited significant suppression of TNF-α production in response to in vitro LPS challenge. Furthermore, both LPS-primed PPARγ-deficient Cre+/+ PPARγ−/− mice and wild-type Cre−/− PPARγ+/+ mice exhibited reduced plasma TNF-α levels in response to a high dose of LPS in vivo. These data demonstrate that PPARγ does not play a role in the LPS-induced tolerant phenotype in macrophages