ABSTRACT
Hemolysis and consequent release of cell-free hemoglobin (CFHb) impair vascular nitric oxide (NO) bioavailability and cause oxidative and inflammatory processes. Hydroxyurea (HU), a common therapy for sickle cell disease (SCD), induces fetal Hb production and can act as an NO donor. We evaluated the acute inflammatory effects of intravenous water-induced hemolysis in C57BL/6 mice and determined the abilities of an NO donor, diethylamine NONOate (DEANO), and a single dose of HU to modulate this inflammation. Intravenous water induced acute hemolysis in C57BL/6 mice, attaining plasma Hb levels comparable to those observed in chimeric SCD mice. This hemolysis resulted in significant and rapid systemic inflammation and vascular leukocyte recruitment within 15 minutes, accompanied by NO metabolite generation. Administration of another potent NO scavenger (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) to C57BL/6 mice induced similar alterations in leukocyte recruitment, whereas hemin-induced inflammation occurred over a longer time frame. Importantly, the acute inflammatory effects of water-induced hemolysis were abolished by the simultaneous administration of DEANO or HU, without altering CFHb, in an NO pathway-mediated manner. In vitro, HU partially reversed the Hb-mediated induction of endothelial proinflammatory cytokine secretion and adhesion molecule expression. In summary, pathophysiological levels of hemolysis trigger an immediate inflammatory response, possibly mediated by vascular NO consumption. HU presents beneficial anti-inflammatory effects by inhibiting rapid-onset hemolytic inflammation via an NO-dependent mechanism, independently of fetal Hb elevation. Data provide novel insights into mechanisms of hemolytic inflammation and further support perspectives for the use of HU as an acute treatment for SCD and other hemolytic disorders.
Subject(s)
Cyclic N-Oxides/pharmacology , Free Radical Scavengers/pharmacology , Hemoglobins/metabolism , Hydroxyurea/pharmacology , Imidazoles/pharmacology , Leukocytes/drug effects , Nitric Oxide/metabolism , Anemia, Sickle Cell/blood , Anemia, Sickle Cell/drug therapy , Anemia, Sickle Cell/pathology , Animals , Cell Movement/drug effects , Disease Models, Animal , Hemolysis/drug effects , Humans , Hydrazines/antagonists & inhibitors , Hydrazines/pharmacology , Inflammation/blood , Inflammation/drug therapy , Inflammation/pathology , Leukocytes/metabolism , Leukocytes/pathology , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Nitric Oxide Donors/antagonists & inhibitors , Nitric Oxide Donors/pharmacology , Primary Cell Culture , Tumor Necrosis Factor-alpha/pharmacology , Viscosity , Water/pharmacologyABSTRACT
Termites can degrade up to 90% of the lignocellulose they ingest using a repertoire of endogenous and symbiotic degrading enzymes. Termites have been shown to secrete two main glycoside hydrolases, which are GH1 (EC 3.2.1.21) and GH9 (EC 3.2.1.4) members. However, the molecular mechanism for lignocellulose degradation by these enzymes remains poorly understood. The present study was conducted to understand the synergistic relationship between GH9 (CgEG1) and GH1 (CgBG1) from Coptotermes gestroi, which is considered the major urban pest of São Paulo State in Brazil. The goal of this work was to decipher the mode of operation of CgEG1 and CgBG1 through a comprehensive biochemical analysis and molecular docking studies. There was outstanding degree of synergy in degrading glucose polymers for the production of glucose as a result of the endo-ß-1,4-glucosidase and exo-ß-1,4-glucosidase degradation capability of CgEG1 in concert with the high catalytic performance of CgBG1, which rapidly converts the oligomers into glucose. Our data not only provide an increased comprehension regarding the synergistic mechanism of these two enzymes for cellulose saccharification but also give insight about the role of these two enzymes in termite biology, which can provide the foundation for the development of a number of important applied research topics, such as the control of termites as pests as well as the development of technologies for lignocellulose-to-bioproduct applications.
Subject(s)
Glycoside Hydrolases/metabolism , Isoptera/enzymology , Animals , Cellulose/metabolism , Glycoside Hydrolases/isolation & purification , Kinetics , Molecular Docking Simulation , Recombinant Proteins/isolation & purification , Substrate SpecificityABSTRACT
Termites are social insects with an extraordinary ability to digest cellulose. Termite societies are structured into castes, and patterns of postembryonic development vary between different termite species. The apterous line may exhibit polymorphism ("physical castes"), in which workers are dimorphic and soldiers can be either dimorphic or trimorphic. We examined the occurrence of polymorphism in the apterous line of Velocitermes heteropterus and determined the developmental pathways for this termite species. We also investigated the expression of the cellulase genes encoding ß-glucosidase and endo-ß-1,4-glucanase among the castes to determine whether there is a difference in digestion and, consequently, a possible division of labor with respect to this activity among the worker castes. The apterous line of V. heteropterus presents individuals of both sexes with two larval instars. The female larvae become major workers, and the male larvae become minor workers and soldiers. The expression of ß-glucosidase was similar within the castes, but the expression of endo-ß-1,4-glucanase was higher in workers than in soldiers. No significant differences were found between minor and major workers. These results suggest that there is no division of labor between the minors and majors with regard to cellulose digestion, with both workers contributing similarly to this process.
