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Question about TEMs and their relation to M1/M2 polarized macrophages

Posted by lhaddad on 24 Apr 2014 at 03:48 GMT

Excellent work!

Doing a literature review, I came across your very interesting and detailed investigation into the expression of Tie2 on M1/M2 macrophages published herein.

According to work from the group of Lewis et al, published in their article entitled "Angiopoietin-2 regulates gene expression in TIE2-expressing monocytes and augments their inherent proangiogenic functions.", the majority of monocytes, especially those of an inflammatory phenotype, are Tie2 negative. Only a small subset of monocytes express Tie2 (known as TEMs), and the authors propose that TEMs constitute a pool of circulating monocytes committed to angiogenesis, which you dispute based on the fact that monocyte progeny (M1 and M2 macrophages) expresses Tie2.

Your work and that of Lewis et al made me thin of a few questions for your consideration:

- is it possible that monocytes that don't express Tie2 give rise to Macrophages that express the receptor?

- Could the M2 Macrophages that express Tie2 derive exclusively from TEMs? In other words, could all M2 macrophages come from differentiated TEMs?

- In parallel, is it possible that inflammatory monocytes (which do not express Tie2) would give rise to the M1 Macrophages that expressed Tie2?

- If you use a population of monocytes enriched in TEMs instead of the total population of monocytes for polarizing experiments, would the ratio of M1/M2 macrophages expressing Tie2 change?

No competing interests declared.
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