On page 12 and 13, Moalem explains specifically how hemochromatosis helps the immune system. This relates to Big Idea 4: Biological systems interact, and these systems and their interactions possess complex properties. In this case, by protecting us from pathogens, the immune system is responsible for keeping us alive.
If the macrophages have iron, many different kinds of pathogens can take advantage of this iron-filled environment to survive and reproduce more quickly. This is why iron-deficient macrophages in hemochromatosis patients are better at killing bacteria. There is no food for the bacteria in the iron-deficient cells.
When a macrophage encounters a bacteria, the macrophage will commence phagocytosis. What happens in this process?
However, iron-deficient macrophages are not all-powerful, since there are also some pathogens that consume other things besides iron for its food. Please research a bit and tell us about a disease like this (e.g., Lyme disease). What do you think could be the next step for research to find out what we can do to combat these kinds of diseases?
If someone were to cut you across the forearm with a dirty knife:
What kind of barriers did the knife penetrate, and what kind of defenses will take over from this point onwards?
What would you see happening? What would happen both microscopically and macroscopically?
(Hugo Lee; hlee3@students.d125.org)
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ReplyDeleteAs Dr. Moalem points out in his book, iron allows bacteria to thrive, as many species use iron for food. Unfortunately, hemochromatosis leads to higher levels of iron in the body because the gene that regulates iron absorption is defunct. The high levels of iron associated with hemochromatosis would lead one to believe that they would be more susceptible to bacterial infection because people with hemochromatosis have more food for the bacteria to survive and reproduce. However, when the body is infected with bacteria, the body automatically “blocks” iron by having proteins bind to the iron, reducing the amount of free iron available to pathogens.
ReplyDeleteAccording to a Science Daily article on December 3, 2012, iron is essential for the metabolism of many bacteria. Most species of bacteria have multiple ways to access iron, so even though our body has some lock down mechanisms, it is still possible for most bacteria to acquire iron, which helps them grow rapidly. Being able to block a bacterium’s ability to access iron could prevent the bacterium from becoming pathogenic and causing infection. One of the goals the article states of future research goals is to isolate the antibodies that block iron uptake. If we can isolate and replicate these antibodies, they could act as a treatment to bacterial infection, aiding the nutritional immunity of our body.
In fact, those with hemochromatosis actually have an advantage when fighting infection, as Dr. Moalem explains. In people with hemochromatosis, macrophages typically have less have less iron. These macrophages are essential to the immune system, as they are the ones that swallow up pathogens and break them down. Certain diseases can utilize the iron in macrophages to their advantage--- the iron in macrophages can actually be used against the immune system. Therefore, the fact that in people with hemochromatosis, macrophages have less iron gives them a selective advantage when fighting disease.
The relationship between iron, bacteria, and macrophages represents Big Idea 4 because there are two biological systems interacting: the immune system and bacteria. The interaction between the two is affected by iron present in the human body. The presence of iron, or lack there of can affect the growth of bacteria, which can affect the immune system and the human body. The relationship between these three is what defines hemochromatosis and other iron based diseases as selective advantages or selective disadvantages.
Even though a disease like Lyme disease may not thrive on iron, the idea behind treating it could be the same. If researchers could identify what a bacterium needs to survive, scientists could potentially limit the supply of that food, therefore stopping the bacterium’s ability to go through binary fission and replicate. Currently, Lyme disease is treated with antibiotics, a much simpler solution in which the cell wall of the bacterium is destroyed, therefore killing the pathogen.
If someone were cut by a knife, the inflammatory response, a non-specific immune response, would be triggered. The knife would have penetrated the first line of defense, the skin. The cells damaged by the knife would release histamine, which would dilate the capillaries, increasing blood flow to the damaged region. The blood would increase the amount of macrophages in the damaged area. The macrophages would eat and break apart the pathogens that were on the knife and have now entered the body. Microscopically, we would see these macrophages swallowing these pathogens (bacteria, viruses) and breaking them apart. Macroscopically, we would see swelling because of dilated capillaries, redness because of increased blood flow, and we would be able to feel heat because of pyrogens, which act as a positive feed back regulator.
Kansas State University. "Research shows iron's importance in infection, suggests new therapies." ScienceDaily, 3 Dec. 2012. Web. 15 Apr. 2013.