Читать книгу Alzheimer's Disease - Michelle Deetken - Страница 15

The last major player in Alzheimer's disease is the captain of the team: inflammation. Inflammation is an active part of the immune system where the response may vary greatly, depending on the playing field. This team captain is playing to win at any cost because every cell in the whole body depends on the captain for protection. Inflammation is the body's best defense against an enemy, whether it is an injury, an infection, or an invading pathogen. Antioxidants cruising throughout the body are the first line of this defense. They give up their electrons to stop free radicals as part of their job, with new recruits taking over as the used up ones retire. When the system is overwhelmed due to oxidative stress and there are no new antioxidant recruits, damage to the cells occurs. A distress signal is sent out to the immune system. Localized tissue hormones called prostaglandins, which are important to the whole immune system, send out the distress signals. While the remaining antioxidants are working hard to minimize the damage, inflammation is preparing its team by calling on the immune response to examine the damage, help isolate the area, and mobilize immune molecules to the site of the damage. Pro-inflammatory genes are also activated, leading to the release of immune molecules called cytokines, chemokines, and adhesion molecules. Counter regulatory or anti-inflammatory pathways are simultaneously activated to keep the inflammatory response under control. This activation allows repair and healing to take place after the attack. When the inflammatory response is acute, the inflammation will last only a few days, similar to getting a cut or contracting the flu. But low-grade, chronic inflammation may last for several weeks, months, or even years. Chronic inflammation renders the counter anti-inflammatory pathways inadequate in order to control the immune system's response, and repair is never fully completed because of the positive feedback loop. This chronic inflammation may lead to excessive damage to cell membranes, proteins, lipids, DNA, and RNA. The damage may be so severe that it compromises tissue and organ functions as in the cases of arteriosclerosis, arthritis, tumor development, and dementia.