P0712 - B. infantis EVC001 Metabolites Improve Enterocyte Proliferation In Vitro

Bacterial derived metabolites such as short chain fatty acids (SCFA) are important for host cells to maintain homeostasis and ability to influence immune development. Given previous findings that show exclusively breastfed infants colonized with B. infantis EVC001 have significantly increased total fecal organic acids, specifically acetate and lactate, compared to infants not colonized with B. infantis, we investigated the effect of fecal water (FW) from two distinct populations on enterocyte proliferation and morphology in vitro.

FW were derived from stool samples collected from infants colonized with B. infantis EVC001 (EVC001) and infants not colonized with B. infantis (controls). FW were added to adult and premature enterocyte cell lines to assess growth, proliferation and cytotoxicity. Treated cell lines were then challenged with pathogen derived LPS and cell integrity measured with TEER and FD4.

Intestinal epithelial cells (IECs; Caco-2 and HIEC-6 cells) exposed to EVC001 FW showed significantly increased proliferation as shown by cell count and real-time ATP expression compared to medium alone and control FW (P < 0.0001). Conversely, decreased lactate dehydrogenase activity, an indicator of membrane integrity, was significantly decreased in enterocytes exposed to control FW compared to EVC001 FW (P < 0.01). Lactate and acetate, added at median physiological concentrations found in EVC001 infant FW, significantly increased Caco-2 cell proliferation compared to medium alone (P < 0.01, P < 0.05, respectively), while control levels of these bacterial metabolites did not significantly increase Caco-2 cell proliferation. Physiological concentrations of butyrate or formate from EVC001 or controls did not increase proliferation rates of IECs. Furthermore, B. infantis EVC001 FW contributed protective effects by maintaining greater cell integrity than control FW during LPS challenge.

EVC001 FW and specific bacterial metabolites, lactate and acetate, significantly increased enterocyte proliferation compared to control FW and medium alone, while control FW negative affected cell growth, membrane integrity and cell morphology. These data suggest that metabolites produced by B. infantis EVC001 promote enterocyte growth and improve intestinal integrity in both adult and premature infants.