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Every Month: a Review of Major Teaching Points

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A Power Program for Student Review

Course Coverage 2016

  • Jan Muscles
  • Feb Meals
  • Mar Metabolism
  • April Nutrition
  • May Metabolic Syndromes
  • June Diabetes
  • July Diabetic Complications
  • Aug Longevity
  • Sept Atheroma
  • Oct Carcinoma
  • Nov Aging
  • Dec Mind & Memory
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The world we live in is a world teeming with tiny creatures, all invisible to the naked eye. Many are keen to make a living by hitching a ride on our skins, in our airways or down along our digestive tracts. Most are harmless, indeed, some are quite beneficial. Only a few are lethally dangerous, and against those dangerous, life-threatening ones, we’ve evolved several defense systems. Our skins are hard to penetrate, making it defense guard  number one…while we produce layers of protective mucus to line our airways and digestive tracts. Finally, and most importantly, we have powerful defenses employing killer soldier white blood cells armed with grasping and disabling antibodies.

The immune system is a collection of cells made mostly in the bone marrow, lymph glands and the digestive tract. They circulate in the blood on patrol, to keep a policeman’s eye out for strangers in the neighborhood. But such strangers…‘foreign’ cells…are produced in error regularly during the billions of replications taking place in all tissues every day. It’s the normal repair and replacement of old or worn out cell machinery. They are cancer cells and our immune system defends us against them at all times, a surveillance ability that falters as we age, and is one reason why cancer is more common during the second half of life.

So powerful a defense is our immune system (think atomic weapons) that it must be carefully contained and constrained against accidental release and self-damage. It is a complicated system to activate, in order that we do not readily and unintentionally attack our own tissues…what immunologists describe as more checks and balances than a democratic government.

There are three types of immune cell…with well-defined particular assignments…primarily against invading microbes. One type attacks and digests…another type of immune cell neutralizes with a natural stopping power…while a third type copes with invaders by delivering or crafting anew, proteins called antibodies. All these defenses act together around any damaged cells in a process called inflammation…while at the same time sending alarm signals into the circulation that mobilize the whole body for defense and protection. Together, they are a defensive arsenal that sometimes gets out of control to causes an  auto-immune disease.

For the normal immune system to work, it needs a supportive bath of circulating plasma proteins…some 18 of them, known collectively as Complement. They must be lurking in the neighboring circulation for an immune process to become engaged. Complement functions something like the blood’s clotting mechanism with a cascade of steps, now known to immunologists as the Complement Pathways.

With Compliment ever in the background, foreign proteins from invading bacteria are recognized as non-self by circulating white blood cells. They come from bone marrow, lymph nodes and from an early-life organ called the thymus gland. These three differently-sourced white blood cells are drawn to any site of invasion or damage by cries for help released by the injured tissue into the blood. Such signals are called cytokines, and together with circulating dead cell bits, they rally immune defenses.

The immune system’s initial response to tissue damage or invasion involves soldier cells engulfing and digesting (assisted by Compliment chemistries) any virus or bacterium or all bits of dead tissue debris. The invaded site where this defensive action takes place is inflamed, becoming red & warm, swollen & tender….except in the brain.

The brain is protected from most immune system reactions by a tissue wall called the Blood-Brain Barrier. It is thought to be an evolutionary legacy from a time when immune system cells were co-opted into brain building. They became sealed within the Blood-Brain Barrier to prevent them responding to earlier signals of immunity and thus begin damaging the nervous system. These immune cell legacies now work with brain cells to control and improve the functions of developing neuron networks.

A less immediate but greater long-term benefit of the immune reaction involves lymphocytes and their antibodies. They help custom craft proteins to hobble and kill all invaders. They tag cell fragments with antibodies that read Eat Me, guiding the body’s trash collectors in the reticuloendothelial system of spleen and liver. Any given lymphocyte pours out hundreds of different antibodies in its frenzied response to most cries for help. Some are more effective than others, but Complement must also be in the area for an effective full court press.

Things can go wrong with this defense system as mentioned above. At the clinical level it can cause allergies…such as sudden collapse from the proteins in a peanut or a bee sting. It can send the airway into an asthmatic spasm over the protein in a plant’s pollen. It can attack cells in the pancreas, cut insulin production and provoke Juvenile-Onset Diabetes (Type I). Less dramatically, it can falter with age and cause the aches and pains of neuritis, neuralgia or lumbago.

The immune system can influence other diseases. It recognizes the abnormal cells of cancer as strangers, inactivating and killing them. It contributes to heart attacks by aggravating the swellings of cholesterol deposits in atheroma. White blood cells of the immune system cause inflammatory swellings around crystals of cholesterol…bulging up the deposit to further narrow the artery and play precipitating roles in heart attacks, strokes and even heart failure.

Immune reactions have a chemical plasma element in all their activities. Introduced earlier, it involves 18 different proteins that are always circulating and collectively known as Compliment. They must be present for any bacterial invader to be properly attacked and labelled ‘Eat me’ for other large and devouring cells to consume…called macrophages (big eaters). And just as immune cells can mistakenly overreact…so Complement can misfire too…all these interacting elements in immunity and disease are being actively researched in the search for better health care treatments.

Antibody therapies are being researched that depend upon the immune system…by creating for specific patients, their own cancer-specific antibodies. It’s an early expression of Precision Medicine. For other diseases of immunity, other antibodies are being formulated against rheumatoid arthritis and psoriasis…two auto-immune disorders. We are beginning to understand the risks and complexities of these treatments so each requires a black box cautionary warning on their labels…and each application requires close clinical supervision.

Cancers are one of the most troublesome failures of immunity, and become ecosystems of many cells. An aging immune surveillance system fails to recognize and destroy them, so the cancer emerges. Their cells all thrive in the high insulin environment of a Metabolic Syndrome. A stronger immune system can be developed as we get older: by exercising muscle, by encouraging a healthy gut biome, and by consuming a low fat diet of whole foods rich in antioxidants. Preventing it always beats early detection.

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