I, claudin

There is no way that I can blog about the gastrointestinal (GI) tract without making mention of that wonderful barrier separating gut contents from the other recesses of our body. Without being too dramatic, I could probably say that I owe my livelihood to the gut barrier; as a consequence of much of my research career heading towards some involvement for the gut barrier at least in some cases of autism spectrum conditions.

A recent paper brought all the years of reading on this subject back to me with the suggestion of a link between intestinal inflammation and claudin-1. The paper by Poritz and colleagues* describes how key tight junction proteins like occludin and zonula occludens-1 (ZO-1) are decreased in inflammatory bowel diseases and how treatment of intestinal epithelial cells with the inflammatory cytokine TNF-alpha (sorry about the lack of Greek characters) seems to increase permeability (leaky gut). With all due respect to the authors, these findings are nothing new.

What was slightly more interesting from Poritz however were the findings in relation to the ratio of claudin-1 and occludin (C:O) as a consequence of cell treatment with TNF-a and what this ratio looked like in real life when comparing different intestinal diseases like Crohn's disease (CD) and ulcerative colitis (UC). Answer: decreased occludin and increased claudin-1 in diseased UC vs. non-diseased UC and normal colons and nothing spectacularly different in different disease-states of CD or controls.

Even to an interested amateur like me, this data indicate some things potentially very important: (a) ratios between multiples rather than independent statistics might yield more diagnostic information, and (b) there may be some underlying differences in the way that tight junctions might be affected in UC vs. CD.

I will come back to the leaky gut and various other things related to it at some point in the future no doubt. But for now if you really, really want some extra credits bedtime reading, here is an article that I always found invaluable on the subject (long yawn, adjust reading glasses and reach for that glass of scotch on the bedside table).

* Poritz LS. et al. Increase in the tight junction protein claudin-1 in intestinal inflammation. Dig Dis Sci. October 2011.