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Scientists Focusing On How Exercise Raises Immunity

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    Scientists Focusing On How Exercise Raises Immunity

    Source:   University Of Illinois At Urbana-Champaign
     Scientists Focusing On How Exercise Raises Immunity

    CHAMPAIGN, Ill. -- An increasing number of doctors and other health experts have been encouraging older adults to rise from their recliners and go for a walk, a bike ride, a swim, or engage in just about any other form of physical activity as a defense against the potentially harmful health consequences of a sedentary lifestyle.

    "Exercise is touted as a panacea for older adults," said Jeffrey Woods, a kinesiology professor at the University of Illinois at Urbana-Champaign, who noted that fitness programs are routinely recommended for people with various health problems -- from diabetes to heart disease.

    Health experts generally recognize that this population benefits from physical fitness, he said. What they don't know is why exercise appears to have certain preventive and restorative health effects. Also unknown is what -- if any -- relationship exists between exercise and immune functioning.

    "Despite the numerous benefits of exercise -- for example, improving cardiovascular and muscular fitness -- we know very little about how exercise affects the immune systems of older adults," Woods said. "Good, bad or indifferent, this information could have important public health consequences for our aging population." For that reason, Woods and colleagues in the university's kinesiology department are conducting research that seeks to establish the link between exercise training and immune function. The field, he said, is still in its infancy, with Illinois researchers among those who are defining it.

    "Our laboratory is using both animal and human models to address the extent to which exercise affects immune functioning and susceptibility to infectious disease in older populations," Woods said. "We have obtained some exciting preliminary data in mice that suggest that moderate exercise or training may boost some immune function measures and reduce mortality caused by influenza.

    While we don't have corollary evidence yet in people, we are in the midst of conducting a large clinical exercise trial in older adults, funded by the National Institute on Aging, that will provide definitive evidence as to whether moderate exercise training influences immune function."

    In the meantime, results of one study conducted in Woods' lab, published in the current online edition of the journal Brain, Behavior and Immunity, indicates that exercise training increases the ratio of naïve T cells to memory T cells in the spleens of older mice. The finding is potentially significant, he said, because, on this measure, "we turn old mice into young mice." When people and animals age, he explained, the thymus, which produces naïve T lymphocytes, shrinks, thus producing fewer naïve cells. "This is one reason that older people/animals have trouble responding to new environmental pathogens."

    And with the recent appearance of so many new environmental pathogens -- from West Nile Virus to SARS and monkeypox -- Woods said the ability to boost the immune systems of the elderly, who are among the populations most at risk from infection, is a worthy goal.

    This story has been adapted from a news release issued by University Of Illinois At Urbana-Champaign.

    I read a report about the thymus yesterday and wondered how it might be related to the weakened immune systems of the spinal cord injured population. I had no idea I would find something like this.

    HNMP-1: a novel hematopoietic and neural membrane protein differentially regulated in neural development and injury.

    Bolin LM, McNeil T, Lucian LA, DeVaux B, Franz-Bacon K, Gorman DM, Zurawski S, Murray R, McClanahan TK.

    DNAX Research Institute, Palo Alto, California 94304-1104, USA.

    The hnmp-1 (hematopoietic neural membrane protein) gene encodes a protein with striking similarity to the tetra-transmembrane-spanning protein encoded by pmp22. hnmp-1 was cloned from an elutriated human monocyte library and is expressed in various human hematopoietic and lymphoid lineages as well as adult mouse spleen and thymus. In the mouse nervous system, HNMP-1 mRNA is temporally expressed by Schwann cells during sciatic nerve myelination. Dorsal root ganglia sensory and spinal cord alpha-motoneurons acquire HNMP-1 protein selectively throughout development. In the fiber tracts of the spinal cord and in sciatic nerve, HNMP-1 protein is axon-associated. Additionally a rapid and sustained level of HNMP-1 expression is observed in response to acute PNS injury. HNMP-1 is constituitively induced in sciatic nerve of Trembler J mice, which are mutant for pmp22 and have a demyelinating/hypomyelinating phenotype. The expression pattern of HNMP-1 suggests a possible role for this molecule during active myelination.

    PMID: 9204931 [PubMed - indexed for MEDLINE] 1&dopt=Abstract

    Essentially, exercise in adults increases T-cell output of the thymus. HNMP-1, which seems to play a role in Schwann cell myelination, is located in the thymus.

    Could this be a link showing remyelination through extensive exercise?

    -Steven's worse than we thought. it turns out the people at the white house are not secret muslims, they're nerds.



      I am not sure that hnmp-1 is the "missing link" between exercise and remyelination. Incidentally, there are many shared receptors and proteins that are unique to neurons and t-lymphocytes. For example, calcineurin is the intracellular phosphatase that is blocked by cyclosporin and FK506. This phosphatase is expressed mostly in lymphocytes and neurons. Another example is the recent discovery that erythropoeitin, a hormone that is previously thought to be just a hematopoietic factor, stimulates neurons and probably neural stem cells to grow, as well as prevent apoptosis; it turns out that neurons express erythropoietin receptors.

      Exercise and activity induces plasticity in the central nervous system. Reorganization of the brain and spinal cord can occur quite quickly, over a period of a week or less. Of course, many people are now beginning to realize that some of these effects may be due to hormones and other factors that we usually associate with non-nervous system functions. The immune system also may play a role in the central nervous system. This is of course the "shtick" that Michal Schwartz introduced several years ago. Many scientists have been looking for "regeneration associated genes" or RAGs. We just finished a study which shows clearly that the pro-inflammatory interleukin-6 (one of the secondary mediators of inflammation) is invariably associated with regeneration in many conditions. So, there are many connections, probably hundreds of them.



        Thanks for the response. I was just thinking that hnmp-1 might be one part of the bigger puzzle. I hadn't read it here [or found it mentioned], so I thought I'd post it.

        BTW, the full text of the article is freely available. It's a few years old, but still interesting.

        -Steven's worse than we thought. it turns out the people at the white house are not secret muslims, they're nerds.