Season of Birth Effect….in Mice

Reynolds JD, Case LK, Krementsov DN, Raza A, Bartiss R, Teuscher C. Modeling month-season of birth as a risk factor in mouse models of chronic disease: from multiple sclerosis to autoimmune encephalomyelitis. FASEB J. 2017. pii: fj.201700062. doi: 10.1096/fj.201700062. [Epub ahead of print]

Month-season of birth (M-SOB) is a risk factor in multiple chronic diseases, including multiple sclerosis (MS), where the lowest and greatest risk of developing MS coincide with the lowest and highest birth rates, respectively. To determine whether M-SOB effects in such chronic diseases as MS can be experimentally modeled, we examined the effect of M-SOB on susceptibility of C57BL/6J mice to experimental autoimmune encephalomyelitis (EAE). As in MS, mice that were born during the M-SOB with the lowest birth rate were less susceptible to EAE than mice born during the M-SOB with the highest birth rate. We also show that the M-SOB effect on EAE susceptibility is associated with differential production of multiple cytokines/chemokines by neuroantigen-specific T cells that are known to play a role in EAE pathogenesis. Taken together, these results support the existence of an M-SOB effect that may reflect seasonally dependent developmental differences in adaptive immune responses to self-antigens independent of external stimuli, including exposure to sunlight and vitamin D. Moreover, our documentation of an M-SOB effect on EAE susceptibility in mice allows for modeling and detailed analysis of mechanisms that underlie the M-SOB effect in not only MS but in numerous other diseases in which M-SOB impacts susceptibility.

There is evidence that the month of birth can influence your chance of developing MS. This has been suggested to be evidence in support of the vitamin D hypothesis. So now we have an mouse study claiming that there is variation in mice. When there is a low birth rate the animals were less susceptible to EAE. They say that the immune responses were less, which surely you would expect if they are less susceptible. 

What are the factors that control this, so you have an endless set of possibilities to test. However, do animals that are noctural have the the same selective pressures as humans that are active during the day and get exposed to the sun. Where do you stop?

Animals are supposed to be kept in light and humidity and temperature controlled environments, with no windows so they are never going to see sun, but I would say that we have seen times when animals are more susceptible than other times. It can’t be vitamin D from sunlight:-)

Would I say this is predictable, I’m not sure.
I could check we have twenty years of data, not sure I can be bothered, other people will do this. Maybe a student project, but I suspect the influence will be minor.

Are animals completely controlled from knowing there is a change in the environement. I’m not sure and you often have more problems when the air temperature is very hot or very cold and many animal houses cannot cope to control temperture properly.

However, you can spot differences. My old boss could not repeat an experiment that was done in the states, and they felt it was vitamin C levels in the guinea pigs, so once a week on thursdays they used to get fed raw cabbage, which they absolutely loved. I would even say they used to squeak more, with excitement from wednesday and thursday morning. Maybe they could smell the cabbage delivered on wednesday?  The experiment then worked

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