Patterico's Pontifications

12/6/2007

Medical Advances: Innate vs Adaptive Immunity

Filed under: General — DRJ @ 6:32 pm



[Guest post by DRJ]

There are many bright, dedicated scientists throughout the US and the world doing excellent medical research. Stories like this illustrate why American medical researchers are among the world’s best:

“The tiny mice didn’t realize that the gas they were inhaling would save their lives as they scampered around a plastic container in a Houston laboratory. In a few hours, these experimental mice — along with others who hadn’t had a turn in the container — would be exposed to pneumonia. All of the untreated mice would die. All that had been exposed to the aerosol would survive.

Conducted by a team of scientists at the University of Texas M.D. Anderson Cancer Center, the experiments demonstrated a concept that could revolutionize the way public health planners approach outbreaks of infectious disease. The aerosol — a purified extract of a common bacterium — stimulates the lungs to vigorously reject pathogens. In addition to finding a bacterium that’s effective for this purpose, the method of delivering it directly to the lungs is important so that the bacterium can boost the immunse [sic] system.”

The scientists tried something new – stimulating the innate immune system to reject all pathogens rather than targeting the adaptive immune system (which is typically done through vaccines) to reject selected invaders:

The new aerosol targets the innate immune system, which is different from the adaptive immune system that most people are more familiar with. Vaccines — which teach the body to build up antibodies, then recognize and destroy invaders — target the adaptive immune system. Only higher vertebrates, such as birds and mammals, have this component of the immune system.

More common to all life is the innate immune system, which doesn’t recognize specific invaders, but rather generally recognizes and reacts to all pathogens in a generic way. The approach by M.D. Anderson scientists to the pathogens is novel in that it seeks to bolster the innate, rather than the adaptive, immune system. They presented their study results today at the annual meeting of the American Society of Cell Biology in Washington, D.C.

“The aerosol stimulates an innate immune system response in the lung lining that kills the invading pathogens, virtually on contact,” said Brenton Scott, a researcher in Dickey’s lab who led the study.”

The treatment offers protection against pathogens like anthrax even if it’s given just hours before exposure, and it offers some benefits after exposure:

“Unlike vaccines, which must typically be given a week or more before exposure, the new aerosol is highly effective against a host of pathogens — including anthrax, influenza and even bubonic plague — if given just a few hours before infection. The new drug and its delivery system even have some benefit if given after exposure.”

The results were impressive against other pathogens, too:

“In their experiments, the scientists let mice breathe the special, aerosolized bacteria for 20 minutes. Then, within four to 24 hours, the mice were exposed to various pathogens. After that, all of the mice exposed to the Staphylococcus aureus bacterium survived, as did 90 percent of those exposed to influenza A, 60 percent of those exposed to the plague and 30 percent exposed to another potential bioterror agent, tularemia, survived.”

One researcher noted that the brief duration of protection, problems with delivery, and the medical establishment’s long-held preference for vaccines had previously discouraged research in this area:

“Unlike a vaccine, which confers long-term protection, the aerosol provides protection for only a few days.

Dr. David Corry, an assistant professor at Baylor College of Medicine who also has begun working on stimulating the innate immune system to ward off pathogens, said the field is full of potential. “Until recently, no one has thought much about stimulating the innate immune system, partly because while it’s quick on, it’s also quick off,” Corry said. “But this new research shows you can stimulate the innate immune system to be highly protective. This is an idea that has been untapped and an opportunity missed, so it’s something that has great potential for development.

Corry said several impediments have held up the development of drugs to boost the innate immune system. Foremost, he said, is that targeting this aspect of the immune system rather than the adaptive immune system represents a radical departure from traditional vaccination. Change often comes slowly in science.

And, he said, there are challenges with delivering aerosolized drugs to patients’ lungs. It’s not as easy as taking a pill or receiving a shot because it requires specialized facilities and trained people. Something as simple as an asthma inhaler wouldn’t suffice.”

M. D. Anderson scientists began this research to help cancer patients who are more susceptible to pneumonia and other infectious diseases, but it’s not hard to see how it might also be useful to protect people against bioterrorism. Human trials may begin as early as 2009 and will initially target leukemia patients “whose immune systems are among the most compromised of all cancer patients.”

More good medical news: “Using a new type of stem cells made from ordinary skin cells, U.S. researchers said on Thursday they treated mice with sickle cell anemia, proving in principle that such cells could be used as a therapy.”

As the Instapundit says, bring it on.

— DRJ

3 Responses to “Medical Advances: Innate vs Adaptive Immunity”

  1. But, if Kerry/Edwards had won, Christopher Reeve would still be alive today.

    The stem cell debate was always lost on me, because it was always vague promises of future miracles, and overselling he potential positives of it. Reality is more likely to be that just the natural innovation amongst the best and the brightest, 10 years from now, will make people look back at how silly that whole debate was.

    And I just find that inate immune system approach fascinating, and brilliant beyond words, in its simplicity.

    JD (2c9284)

  2. There’s a little clearer coverage here:
    http://www.sciencedaily.com/releases/2007/12/071203103414.htm

    And actually, fish *do* have the adaptive wing of the immune system…

    sondbax (3a9273)

  3. Good link, sondbax. Thanks.

    DRJ (a6fcd2)


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