TeachableMedicalNews article 06262020

Teachable moment in classrooms:

  1. cellular basis of life chapter – transcription
  2. skeletal system chapter – actions of osteoblasts and osteoclasts
  3. skeletal system chapter– osteoclast form from monocyte
  4. microbiology – reverse transcriptase of HIV
  5. microbiology – lifecycle of retroviruses like HIV

The news item:  A recent news article reminded us the bone fractures suffered by  AIDS (acquired immunodeficiency syndrome) patients as the result of the side effect of their treatment:

https://www.washingtonblade.com/2019/07/18/gilead-hit-with-more-lawsuits-over-harmful-side-effects-of-aids-drug/

While the report is about lawsuits against the maker of one antiviral drug, the article is a reminder of the substantial bone loss in treated AIDS patients.

So, Why Do I Care??  In the USA there are over 500,000 AIDS patients who receive antiviral treatment to manage the disease. Most of them are in the 20-40 age range, so their bone health will affect them for decades of their lives. In addition, this surprise side effect may become the motivation for new research into osteoporosis, and that knowledge may improve the living conditions of all patients with osteoporosis.

Plain English, Please!!! First, let’s talk about what is in that antiviral pill. One component stops the reproduction of the virus; this called a reverse transcriptase inhibitor, and chemically it is a nucleotide type of chemical.  The other component stops the release of new virus particles; that is called a protease inhibitor, and chemically it is a small organic molecule.  Neither of these components target bones, so bone loss is an unexpected side effect.

Second, let’s talk about basic bone health. Inside our bones there are two processes that go on 24/7: a bone building action carried out by the cells called osteoblast, and a bone degradation action carried out by the cells called osteoclasts. Bone loss and bone weakening is caused by osteoclast working faster than the osteoblasts. One quirk of osteoclasts is how they come about.  A type of white blood cell (monocyte) moves out from the blood vessels, and enters the bone tissue, and inside the bone several monocytes fuse together to form an osteoclast.

Third, let’s talk about how antiviral treatment is affecting bone health. The main effect is that the reverse transcriptase inhibitor speeds up the formation of osteoclast, so bone degradation will become faster than bone building in the treated AIDS patient. The mechanism of speeding up osteoclast formation is not completely understood. However, this unexpected side effect proves that  bone health may be controlled in novel ways, and so continued research in this area may bring new discoveries and better treatments for osteoporosis.