Winter is cold and flu season.  It also is the season for a myriad of other pathogenic maladies including those of the bacterial kind.  What is the first thought many of us have?  Go to the doctor and get a script for antibiotics.  If you’re the whining, persistent kind you might have a doctor that gives in to your pleas every time you set foot in the office.  But is this the right call?  In many cases, no, it is not.

The evolution of immunity in humans has been a long battle – over 40 million years according to recent research.  This battle has been an on-going struggle of survival between primates and pathogens.  Matthew Barber, Ph.D. at the University of Utah headed a study that examined the DNA of 21 primate species including squirrel monkeys right up to humans.  His study revealed an evolutionary battle over iron circulating in the host’s bloodstream.  Evolution of immunity in primates has centered on this battle, over iron, between bacteria and primates.  This battle has been an important factor in our survival as a species.

How does this nutritional immunity work?  Well, we all are familiar with the outward signs of any infection.  We sneeze.  We get runny noses.  Often our temperature increases.  All of these symptoms are part of our immune system’s attempt to kill these invaders.  What most of us are unaware of is that another battle rages on within our bodies.  It has no real outward signs except when we begin to feel better because the pathogens within us begin to die.  This lesser known defense is known as nutritional immunity.  It works by starving infectious bacteria by hiding the iron circulating in our blood streams, iron the bacteria need very much for survival. This secret weapon of our immune system is a protein, transferrin, that hides the iron in our blood.  If the bacteria cannot get the iron, they die and we get better!  Evolution always works in both directions, and as primates have developed defenses to tackle infectious bacteria, some of these pathogens have also developed their own weapons.  The bacteria that cause meningitis, gonorrhea, and sepsis, have developed their own protein, TbpA (transferrin binding protein) that attaches to transferrin and steals its iron.  They reproduce and we are sicker for much longer as our body try other means to fight the pathogen.

Barber and his team were the first to discover the evolutionary pathway this battle has fought on. By examining the transferrin and TbpA protein in the 21 primate species and dozens of bacterial strains, they determined the accumulated changes in these proteins centered at the point of contact between these two proteins-where the TbpA attaches to the transferrin to steal its iron. They have also discovered that recent changes in transferrin have allowed it to evade the grasp of TbpA.

About 25% of the human population have a unique transferrin protein that prevents it being recognized by several bacterial strains and, thus iron can be hidden from them causing these pathogens to starve.  This evidence provides a recent sign of the evolutionary battle between primates and infectious bacteria.

So… is bugging your doctor for antibiotics when you don’t really need them a good call?  Definitely not.  Your body is designed to fight these little buggers and it has a number of defenses that are designed to be lethal.  Antibiotics are a last-ditch resort.  If your body becomes so overwhelmed you are not getting better then it is time to give in and take the medicine.  But the kicker is the infection must be bacterial for the antibiotics to work.  Viruses are not killed by antibiotics. Antibiotics won’t even make you feel better if your infection is caused by anything but bacteria. Even all bacterial infections can not be treated equally with all antibiotics.  And if your infection is bacterial, you must take the antibiotics as prescribed or you may be a link in the creation of antibiotic-resistant bacteria.

Thus, the study by Matthew Barber and his associates on nutritional immunity as well as the understanding of all natural defense mechanisms of the body are crucial in developing the means to combat these antibiotic-resistant bacteria and other difficult to treat diseases.  Successful evolutionary strategies can be applied in hard situations leading to novel treatments for difficult to combat diseases.

Sources

George Washington University. “Patients don’t understand risks of unnecessary antibiotics, study shows.”  December 15, 2014ScienceDaily. December 18, 2014.

University of Utah Health Sciences.  “Human DNA shows traces of 40-million-year battle for survival between primate and pathogen.” December 11, 2014.  ScienceDaily.  December 18, 2014.

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