In autoimmune conditions such as rheumatoid arthritis, lupus and multiple sclerosis, disease activity can change and often worsens during pregnancy. All conditions disproportionately affect females- in Lupus the gender ratio is 9:1.
This study released in August showed that gut microbiota changes during pregnancy to resemble conditions that would otherwise promote metabolic syndromes, "including weight gain, abnormal glucose metabolism, and inflammation."
"Health-boosting bacteria decreased in abundance, while disease-related bacteria increased in number. In addition, signs of inflammation increased over the course of the pregnancy."
Could this be further evidence of a connection between autoimmunity and gut microbiota? could the changes to gut bacteria and increase in inflammation also be causing the changes to disease activity seen during pregnancy?
http://www.sciencedaily.com/releases/2012/08/120802122506.htm
This is interesting and flies in the face of what happens in IBD. We often (but not always) see decreased disease during pregnancy here. The hypothesis is that pregnancy leads to less immune activation in attempt to tolerate the unborn baby (in a sense a foreign stimulus to the immune system) better.
The alteration in maternal microbiome may be related to changes in dietary habits following an increased appetite during maternity. Disease related bacteria may antagonize each other in a similar way as the health-boosting bacteria do. A reasonable explanation could be the assumption that desease related bacteria have not reached the critical number and the threshold to cause disease.
I would recommend reading [the “soft collagen” hypothesis in the pathogenesis of IBD], published in Medical Hypothesses journal, in order to shape a possible mechanism by which maternal collagen alterations during pregnancy may be responsible for an autoimmunity trend during pregnancy.
""The changes in gut microbes were not related to diet, so we think the immune system or hormones play a role," Ley says."
The paper claimed that there were significant changes in diet. The data are the data, although it is somewhat counter-intuitive.
Pregnancy associated changes in the immune system may also compartmentalized to some extent negating some of the minor systemic changes. A survey of some cytokines done in the paper is a pretty superficial way to probe the immune system. In most biological systems there are dual effects and feedback loops. It is very likely that the minor increases in some pro-inflammatory cytokines are offset by other regulatory immune circuits. The same goes for the seductive division of micro-organisms into good and bad or "health-boosting" and "disease associated". Association does not mean causation. Taxonomy doesn't get very far in understanding what the microbial communities actually do. Metabolic profiling of the microbiota in the paper appeared quite stable, but that is also likely incomplete in understanding all the effects of the commensals.
Hello, sorry for the rushed response Periklis, collagen is an interesting angle- particularly for autoimmune connective tissue diseases.
Christian that is interesting the hypothesis developed for IBD. In another post a scientist mentioned the immune system increases activity during pregnancy as increased gut absorption allows more pathogens through. That could be localized though so both may be true.
If pregnancy causes some autoimmune diseases to worsen or improve, is it an insight into the underlying cause? And does that relate to gut bacteria?
Hi Juliet,
if gut absorption increases during pregnancy will the immune system fight them (increase in activity, inflammation) or tolerate them (decreased activity)? Not sure which one is true.
The difficulty will be how to get same to examine this either way. Stool samples are probably not good enough as faecal flora can differ significantly from ileal or high colonic flora.
Christian
The answer to this question is likely complex; there are many factors at play; in dealing with RA (rheumatoid arthritis), many (but not all) patients actually get better during pregnancy, and this is likely related to genetics as well as the subset or type of RA present. Lupus often (but not always) gets worse during pregnancy or in the post-partum period,
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