AIDS/HIV
General Description
- Acquired immune deficiency syndrome (AIDS) is a disease that acts by lowering
the victims immunity, allowing secondary, unrelated infections to produce fatal
symptoms.
- In 1983, researchers in France and the United States isolated the virus that
produces AIDS. This virus is known as the human immunodeficiency virus (HIV).
Causes
- HIV causes depression in immunity by primarily affecting T-cells, which are responsible
for the bodys ability to defend itself against foreign organisms (acquired immunity).
- HIV appears to preferentially target helper T cells over other cells in the body,
although it has been shown to also be capable of attacking other T cells and monocytes
as well. Once it enters the body, it initially infects helper T cells, causing
flu-like symptoms that last for several weeks. The virus then enters a dormant
period which can range from 6 months to 10 years. Following this dormant phase,
HIV begins its reproductive phase. The virus is released and invades other helper
T cells, destroying them to produce new viruses. This reproductive cycle is capable
of destroying 60 - 90% of the helper T cells in the body within several months.
The result of helper T-cell destruction is a suppression of cell-mediated immunity.
- Once immunity has been suppressed, infectious agents take advantage of the opportunity
to cause secondary diseases. The opportunistic pathogens cause many of the diseases
which are used to diagnose AIDS: pneumonia from Pneumocystis carinii, a
type of skin cancer called Kaposis sarcoma, a liver disease called hepatitis B,
a systemic bacterial infection know as toxoplasmosis, a loss of weight caused by
chromic diarrheas known as HIV wasting syndrome, and a degeneration of functional
brain tissue called AIDS dementia. These secondary diseases are the usual causes
of death among AIDS sufferers.
At Risk
- Initially, AIDS was primarily confined to certain population sub-sets with high
risk for interchanging blood or other HIV-infected bodily fluids. Two groups in
particular, homosexual males and intravenous drug users, were at highest risk.
- Today, the prevalence of HIV has made caution the by-word for all individuals
exposed to blood or other bodily fluids. Stringent pre-testing and handling precautions
are indicated because the ultimate symptoms produced by HIV which ultimately lead
to AIDS can take several years to develop. There are potentially many individuals
who are unaware that they are HIV positive.
Prevention and Management
General:
- At the present time, there is no vaccine or drug to prevent AIDS. The best way
to reduce the risk of HIV exposure is to reduce or eliminate exposure to potentially
infected blood.
- Sexual transmission of HIV, which is the most common mode of infection, can be
prevented by use of barriers such as latex condoms.
- Health care professionals are well aware of the precautions that must be taken
whenever blood is handled. The best course is to assume that the blood is HIV positive,
and to take appropriate measures, such as latex gloves, gowns, and eye protections,
to prevent exposure.
- Advanced cases of AIDS are accompanied by a general wasting of the body (AIDS
wasting syndrome). Many individuals with AIDS also have deficiencies in many vitamins
and minerals.
- Nutrition and nutritional status can have profound effects on immune functions.1 Some AIDS sufferers have shown temporary improvement in their symptoms when put on a
strict nutritional regimen which also included vitamin supplements.2,3
- Recent evidence also suggests that HIV infected individuals are under chronic
oxidative stress which may contribute to many aspects of the pathogenesis of AIDS.4,5 This
has lead to the suggestion that the progression of AIDS may be retarded by supplementints natural antioxidant defenses.6 However, well controlled prospective
clinical trials of the efficacy of antioxidants for AIDS remain to be performed.
- Cognitive and hematopoietic dysfunctions of some AIDS patients is reversed by
vitamin B-12 therapy.7
Abstracts
Liang B, Chung S, Araghiniknam M, Lane LC, Watson RR. Vitamins and immunomodulation
in AIDS. Nutrition 1996 12(1):1-7. Acquired immune deficiency syndrome
(AIDS) is a clinical disorder caused by a retrovirus infection and represents
the end point in a progressive sequence of immunosuppressive changes. Vitamins
can enhance disease resistance in animals and humans. As such they are important
co-factors in optimal functioning of the immune systems. In this article, the
immunological and nutritional modifications caused by AIDS are summarized. The
effects of murine and human retrovirus infection on vitamin status are analyzed
as co-factors in the development of severe immune dysfunction, AIDS. The properties
of immunoenhancing antioxidative vitamins, vitamin A, B6, B12, C, E, and beta-carotene,
which are frequently low in AIDS patients, are evaluated relative to the development
of immunodeficiency during retrovirus infection. Vitamin A, E, and B12 deficiency
accelerated the development of AIDS with low T cells, whereas their normalization
retarded the development of immune dysfunction. The interactions between these
vitamins and the immune system in human AIDS patients and animal models of AIDS
are reviewed. Our purpose is to provide data on how retrovirus infection can
cause nutritional deficiencies that accentuate immune damage and to evaluate
the potential therapeutic role of vitamins in the treatment of immune dysfunctions
in AIDS patients.
Pace GW, Leaf CD. The role of oxidative stress in HIV disease. Free Radic
Biol Med 1995 19(4):523-8. Evidence has accumulated suggesting that HIV-infected
patients are under chronic oxidative stress. Perturbations to the antioxidant
defense system, including changes in levels of ascorbic acid, tocopherols, carotenoids,
selenium, superoxide dismutase, and glutathione, have been observed in various
tissues of these patients. Elevated serum levels of hydroperoxides and malondialdehyde
also have been noted and are indicative of oxidative stress during HIV infection.
Indications of oxidative stress are observed in asymptomatic HIV-infected patients
early in the course of the disease. Oxidative stress may contribute to several
aspects of HIV disease pathogenesis, including viral replication, inflammatory
response, decreased immune cell proliferation, loss of immune function, apoptosis,
chronic weight loss, and increased sensitivity to drug toxicities. Glutathione
may play a role in these processes, and thus, agents that replete glutathione
may offer a promising treatment for HIV-infected patients. Clinical studies are
underway to evaluate the efficacy of the glutathione-repleting agents, L-2-oxothiazolidine-4-carboxylic
acid (OTC) and N-acetylcysteine (NAC), in HIV-infected patients.
References
1 Harbige, LS. Nutrition and immunity with emphasis on infection and autoimmune
disease. Nutr. Health, 10(4):285-312, 1996
2 Liang, B, S Chung, M Araghiniknam, LC Lane and RR Watson. Vitamins and
immunomodulation in AIDS. Nutrition, 12(1):1-7, 1996.
3 Chlebowski, RT, G Beall, L Lillington, EW Richards, BC Abbruzzese, MA
McCamish and FO Cope. Nutritional intervention in the course of HIV disease. Nutrition,
11(2 Suppl):250-4, 1995.
4 Pace, GW and CD Leaf. The role of oxidative stress in HIV disease. Free
Radic Biol Med, 19(4):523-8, 1995.
5 Schwarz, KB. Oxidative stress during viral infection: a review. Free Radic
Ciol Med, 21(5):641-9, 1996
6 Segal-Isaacson, AE and CJ Rand. Antioxidant supplementation in HIV/AIDS.
Nurse Pract, 20(7):11-4, 1995.
7 Herbert, V, W Fong, V Gulle, TS Kasdan. Low holo-transcobalamin II is
the earliest serum marker for subnormal vitamin B-12 (cobalamin) absorption in patients
with AIDS. Am J Hematol. 34:132-139. 1990.
