Study Finds Eosinophils Increase in Mouse Intestines During Pregnancy and Lactation

A Nature research paper reports that eosinophils accumulate in the small intestine of mice during pregnancy and lactation. The cells promote goblet cell differentiation and increased mucus production, which limits pathogen entry. Researchers used a hormone-induced timed-pregnancy mouse model.

They collected small intestinal tissues from mice on gestational day 12 and on day 12 of lactation. Age-matched nulliparous female mice served as controls.

Total immune cell numbers increased in the small intestinal lamina propria of pregnant and lactating mice compared with controls. Eosinophils showed the highest and most sustained increase in frequency during these stages. Measurements indicated a twofold increase in eosinophil frequency and up to a fourfold increase in total cell number during lactation compared with controls.

Eosinophil numbers rose across proximal, middle, and distal regions of the small intestine.

Eosinophils promoted goblet cell differentiation in a stem-cell-intrinsic manner. This led to increased mucus production that limits pathogen entry and dissemination. The intestinal remodelling and innate defence persisted weeks after lactation ended.

The paper states that increased circulating eosinophils have also been observed in postpartum humans. The findings demonstrate that the maternal intestine undergoes remodelling to strengthen innate defence despite systemic immune modulation during reproduction.