Reactive oxygen species (ROS) are key signaling molecules that play an important role in the progression of inflammatory disorders. In the last decade, studies have indicated that ROS, including superoxide and hydrogen peroxide, are crucial components that regulate the differentiation process of osteoclasts. Osteoclasts (OCs), cells specialized for bone resorption, utilize ROS as second messengers during receptor activator of NF-κB ligand (RANKL)-induced differentiation and activation. The purpose of this chapter is to explore the current understanding of reactive oxygen species involvement in bone pathophysiology.
Part of the book: Reactive Oxygen Species (ROS) in Living Cells
Homocysteine, a non-proteinogenic sulfur-containing amino acid, was discovered in 1932, and 30 years passed until, in 1969, for the first time, its involvement in pathology was reported. It was only in the last two decades that homocysteine has become a subject of scientific interest and has begun to be intensively studied. A large number of scientists consider homocysteine as an independent risk factor particularly for cardiovascular disease, while others indicate homocysteine as a marker of this disease. Both sides bring scientific arguments for their opinions, yet the dilemma of homocysteine characterization still persists. Although the reported studies do not lead to a unique answer, it is generally accepted that homocysteine is associated with vascular dysfunction. Numerous scientific data show that the link between homocysteine and inflammation is achieved via the reactive oxygen species (ROS) pathway. The latest data indicate hydrogen peroxide as a possible messenger in cellular signaling in physiological or pathological processes and present the consequences of disturbing the oxidation-reducing balance. In this chapter, we present the latest scientific evidences gathered from the literature for both hypotheses regarding homocysteine involvement in pathology, and we propose a possible mechanism of action for homocysteine, based on our preliminary (yet unpublished) work.
Part of the book: Non-Proteinogenic Amino Acids