Excess of nutrient-induced morphofunctional adaptation and inflammation degree in a Caco2/HT-29 in vitro intestinal co-culture

Abstract

Objectives: The intestinal cell function can be modulated by the type and quantity of nutrients. The aim of this study was to evaluate the effects of an excess of nutrients on intestinal morphofunctional features and a possible association of inflammation in a 70/30 Caco2/HT-29 intestinal in vitro co-culture.

Methods: An excess of nutrients (EX) was obtained by progressively increasing the medium change frequency with respect to standard cell growth conditions (ST) from confluence (T0) to 15 d after confluence (T15).

Results: In comparison with the ST group, the EX group revealed a maintenance in the number of microvilli, an increase in follicle like-structures and mucus production, and a decrease in the number of tight junction. The specific activity of markers of intestinal differentiation, alkaline phosphatase and aminopeptidase N, and of the enterocyte differentiation specific marker, dipeptidyl peptidase-IV, were progressively raised. The transepithelial electrical resistance, indicative of the co-culture barrier properties, decreased, whereas Lucifer yellow P_app evaluation, an index of the paracellular permeability to large molecules, showed an increase. Reactive oxygen species and nitric oxide production, indicative of an oxidative status, together with interleukin-6, interleukin-8, indicative of a low-grade inflammation, and peptide YY secretion were higher in the EX group than in the ST group. The differences between ST and EX were particularly evident at T15.

Conclusion: These data support the suitability of our in vitro gut model for obesity studies at the molecular level and the necessity to standardize the medium frequency change in intestinal culture.

Keywords: Caco2/HT-29 co-culture; Excess nutrients; Inflammation; Oxidative status; Permeability; Transmission electron microscopy.