Perugini, J.; Bendinelli, P.; Scopini, E.; Galli, C.; Cattaneo, S.; Bonfatti, V.; Cinti, S.; Finco, A.; De Noni, I.; Giordano, A.; Ferraretto, A.

Obesity is associated with chronic low-grade systemic inflammation of adipose tissue and is often linked to intestinal 22 epithelial barrier (IEB) dysfunction. The present study aimed to evaluate the effects of in vitro gastrointestinal digests of 23 bovine milk containing A1B or A2 {beta}-casein variants on leaky IEB and adipocyte inflammation. Digests of A1B (DA1B) 24 and A2 (DA2) milk were administered to an in vitro Caco-2/HT-29 intestinal cell co-culture mimicking a leaky gut. 25 Intestinal absorbed fractions derived from A1B (MA1B) and A2 (MA2) were administered to hMADS adipocytes. DA1B 26 and DA2 did not modify intestinal permeability, either in the absence or the presence of inflammation. DA1B reduced 27 Claudin-1 mRNA, as well as zonula occludens-1 mRNA and protein expression. Both DA1B and DA2 increased inter- 28 leukin-8 expression, but only DA1B increased tumor necrosis factor-. In human adipocytes, MA1B, and to a lesser 29 extent MA2, increased the expression of pro-inflammatory markers monocyte chemoattractant protein-1 and interleu- 30 kin-6, while reducing adiponectin levels. DA2 preserved in vitro leaky IEB integrity and exhibited a lower inflammatory 31 potential in both leaky gut and adipocytes compared to DA1B. This study is the first to establish a link among A2 milk, 32 leaky gut syndrome, and obesity.