Get Sick For Good Microbes!

Previously I discussed the relation of the human microbiome to malnutrition. Furthermore, in the previously discussed study, the twin that developed kwashiorkor had an underdeveloped microbiome for their age (3 years). Microbiomes, like many parts of our body, continue to grow and develop as we age. So, how does this developmental process of the microbiome? Well, although babies are born with personal assortment of microbes recieved from their mom, it takes a couple of years for the micrbiome to fully form. A recent study suggests that the immune system of babies are actively suppressed in order to further develop this microbiome (Elahi, et al, 2013). Previously, the lack of immune defense in infants has believed to have been related to immature immune cells. Nevertheless, this particular study found another possible explanation. Researchers discovered that blood cells found in infant umbilical cords (called CD71 cells) actually act as an immunosuppressive. Researchers hypothesized that perhaps the purpose of CD71 cells is to combat the natural inflammation that would occur upon abrupt colonization of bacteria. Furthermore, by suppressing the immune system, babies could catch good microbes (along with the cold-inducing microbes) (Elahi, et al, 2013). However, this study did not investigate the amount of time babies have a suppressed immune system; but it's speculated that the immune system would strike a balance a couple of years after birth.  

Who knew being sick had its benefits?

Reference:

Elahi, S., Shaaban, A. F., Kinder, J. M., Ertelt, J. M., Way, S. S., Kalfa, T. A., et al. (2013). Immunosuppressive CD71+ erythroid cells compromise neonatal host defence against infection. Nature, 504(7478), 158-162. Retrieved May 16, 2014, from http://dx.doi.org/10.1038/nature12675

Malnutrition and Microbes

I've previously discussed how gut bacteria can effect the metabolism  as well as the immune system; but could gut bacteria be related to malnutrition? Kwashiorkor is a form of deadly malnutrition that occurs when there is a lack of protein in the diet. However, the mystery is that children who suffer from kwashiorkor can can still get this disease despite having the exact same diet as children who remain unaffected.
A study investigating this mystery researched 300 pairs of twins (both monozogtic and dizygotic) from Malawi, a country in southern Africa where kwashiorkor is fairly common. The researchers continued to study the 300 pairs of twins through the first three years of life. It was observed that although none of the twins were malnourished to begin with, often times one twin out of the pair would develop kwashiorkor and the other would remain healthy. Researchers studied the feces of the infected children before and after a therapeutic food intervention in order to see what sort of microbes the children had in their gut. It was discovered that children who suffered from kwashiorkor had abnormal communities of microbes which only improved temporarily with treatment (Smith, et al, 2013).
Researchers then transplanted gut bacteria from three pairs of twins into special mice who completely lacked a microbe community due to being raised in a sterile environment. After receiving a diet similar to that of what children have in Malawi, mice who received the microbes from the ill children started loosing weight. This suggests that perhaps gut bacteria play an important role in malnutrition, and that malnutrition could potentially be treated with strains of probiotics in the future. Nevertheless, questions still remain about how these children are being cared for at home and why generally one out of each pair become malnourished (Smith, et al, 2013).

Reference
Smith, M. I., Knight, R., Concannon, P., Rich, S. S., Kau, A. L., Cheng, J., et al. (2013). Gut Microbiomes of Malawian Twin Pairs Discordant for Kwashiorkor. Science, 339(6119), 548-554.