HIV is a deadly virus that infects individuals for life. The end stage of the infection is known as AIDS or Acquired Immune Deficiency Syndrome. During this period of the disease individuals usually develop one or more infections common to the general public. For the general population the infections usually last 7-10 days at worst, where people with AIDS can be sick for months and in many cases may die from them.
Doctors have been prescribing medications to treat HIV for more than two decades. When retroviral drugs to fight HIV were first developed, doctors thought the disease would be stopped. But after more than 25 years, the virus persists, with some holding the belief it is stronger than ever.
Doctors and scientists have been trying to determine why the virus is so difficult to treat. They have investigated how the virus replicates, where it lives in the body, and what its susceptibilities are. A new study from the University of California at Davis was published in the Journal of Virology points to the gut as an important clue. The study found that HIV hides in the gut mucosa, particularly in the lymphodi tissue in the digetstive tract where it replicates and damages important immune cells needed to fight off invading organisms that can cause deadly infections.
In the gut there are specialized immune cells, GALT (Gut associated lymphoid tissue), that are responsible for about 70% of the immune cells produced in the adult. It is these particular cells that are the target of the HIV virus. HIV must replicate in a cell of its 'host'. The CD4 cell is the specific cell HIV replicates in. Once replication is complete the virus destroys the cell. As more virus replicates and more cells are destroyed the immune system begins to weaken. When an individuals condition develops into AIDS, there are less than 400 specialized CD4 cells, therefore rendering the immune system almost defunct.
The mucosal barrier of the gut represents the organ with the largest surface area in the human. Maintaining a proper barrier is key to ward off invading organisms from our food and drink as well as organisms that are spread through other body fluids that seek to enter the body via the digestive tract. When the GALT immune cells are destroyed by as much as 70% the defense of the gut is destroyed in equal magnitude.
The researchers believe also that HIV is difficult to treat because it hides in the mucosa, where the drugs cannot affect it. Most drugs have to be taken into the blood stream and metabolized in the liver to become active. Once the drugs are activated, they no longer reach the gut mucosa in high amounts.
The researchers studied 10 patients with HIV who were being treated with HAART (highly active antiretroviral therapy) taking samples of their blood and gut tissue. They made long term comparisons over several years and compared results pre and post-treatment. They found that those with healthy gut mucosa had less infection and less severe forms of the disease. Some had increased inflammation in the gut, fewer immune cells, and overgrowth of unhealthy bacteria and were more likely to have a more severe or advanced form of the disease. Also those with healthy guts responded to treatment with the HAART drugs better.
The findings can help healthcare providers formulate treatments that can improve outcome. In particular doctors need to pay more focus to the gut and treating it when needed.
Posted by Dr. Christina Gutierrez on August 7, 2006 03:51 PM
