Heavy metal exposure and the human immune system

The role of interleukin-12 in the heavy metal-elicited immunomodulation: relevance of various evaluation methods
Original source: Journal of Occupational Medicine and Toxicology 2008, 3:25
Authors: Nasr YA Hemdan
Publication date: 6 November 2008
DOI (digital document ID): 10.1186/1745-6673-3-25
Requires subscription? No
Publicly-available abstract: Yes

Synopsis:
Heavy metals are known to affect the actions of T-helper (Th) cells and thereby affect the development of illnesses and disease. Interleukin (IL)-12, a crucial one of these cells, is one of the Th cells affected by outside agents. IL-12 promotes systemic inflammation and affects the body's response to disease. The author is testing to see if IL-12 levels are affected by heavy metal exposure.

Tests were run using both cultured human immune tissues and live mice. The human cells were cultured without exposure to either cadmium (Cd) or mercury (Hg). The mice were continuously exposed to sublethal doses of Cd or Hg salts for 3 or 5 weeks. Several different methods were used to evaluate the IL-12 levels.

IL-12 levels were dependent on levels of exposure to Cd or Hg, and on interferon-gamma (IFN-gamma) levels. The various measurement approaches were considered equally valid. In the absence of heavy metals, the interaction between IL-12 and IFN-gamma was shown to depend on the disease microorganism to which the cells were exposed.

Reliability:
The author is associated with several accredited institutions and appears to specialize in immunology. The tests were run redundantly using several different methods and came out the same each way, suggesting accuracy in the results received. The study was published in a peer-reviewed journal. The number of subjects (both human and rodents) was not explicitly stated, so it is difficult to tell if the results may be skewed by small sample size.

Practical Applications:
We are increasingly exposed to heavy metals and other environmental toxins; these are now shown to depress our immune systems. One of the difficulties in living long-term with diabetes is that the immune system is compromised. (Type 1 diabetes is an autoimmune disease.) This suggests that people with diabetes may need to be more careful than non-diabetics in minimizing our exposure to heavy-metal toxins. (Certain fish are known dietary sources of these toxins.)

I was curious to find out if the author had made any correlation between heavy-metal exposure and the development or progression of autoimmune disease. (He did not.)

This synopsis was based on the entire article.

Could antioxidants fight diabetes?

The role of antioxidant supplement in immune system, neoplastic, and neurodegenerative disorders: a point of view for an assessment of the risk/benefit profile
Original source: Nutrition Journal 2008, 7:29
Authors: Daria Brambilla, Cesare Mancuso, Mariagrazia Rita Scuderi, Paolo Bosco, Giuseppina Cantarella, Laurence Lempereur, Giulia Di Benedetto, Salvatore Pezzino, and Renato Bernardini (corresponding author)
Publication date: 30 September 2008
DOI (digital document ID): 10.1186/1475-2891-7-29
Requires subscription? No
Publicly-available abstract: Yes

Synopsis:
The authors discuss the use of antioxidant foods and supplements in the treatment of chronic disease. They are particularly interested in the effect of dietary antioxidants on the management of cancer and neurological and immune disorders. They are particularly interested in antioxidant enzyme systems, such as the heme oxygenase/biliverdin reductase system, which may be directly affected by the presence of antioxidants in the diet. They believe these enzyme systems may efficiently reduce oxidative damage and minimize the progression of disease-related oxidative stress. The clinical effects of dietary antioxidants is still under debate. Along the same lines, the excess consumption or bioavailability of fat-soluble vitamins has been associated with increased incidence of cancer.

The concepts of "free radicals" and "oxidative stress" are defined, and are said to damage the body's proteins, DNA, and lipids (fats). The authors mention some of the pathways in which oxidative stress occurs and can be measured, how oxidation can affect the digestive and immune systems, and how micronutrient deficiencies can cause the immune system to be depressed. This includes the discussion of methods for determining how the human body uses vitamins, minerals, and antioxidants, how chronic and autoimmune diseases may be affected by oxidative stress, and how antioxidants -- both alone and along with other chemicals -- may affect the disease process.The authors caution that the potential benefit of using antioxidants to reduce this damage must be weighed against the possible damage they might cause if overused, and that a thorough understanding of how these nutrients act chemically, in the cellular environment, and on a person as a whole.

Reliability:
The authors are associated with the pharmacology departments of their universities. The issues discussed are related to the pharmacological properties of nutrients and nutrient supplements (nutriceuticals). This is a general article; while specific diseases, oxidants, and disease pathways are mentioned, no quantitative analysis is given. The authors are optimistic about the use of antioxidants in the management of chronic illnesses, but are concerned about people blindly adding antioxidant supplements before their effects are thoroughly tested.

Practical Applications:
While neurological disorders are given particular emphasis, that the authors touch on "chronic diseases" and "autoimmune disorders" suggests that their findings may be useful in the use of dietary supplements for both Type 1 and Type 2 diabetes. Better understanding of how oxidative stress affects diabetes, and controlled experiments using particular antioxidants, are both needed both to verify whether or not this will work for most people, and to determine what specific antioxidants and combinations should be taken.

For further reading:
Check the authors' bibliography for studies relating to specific diseases.

This synopsis was based on the entire article.