Spermidine Prevents Polarity Loss of Absorptive Enterocytes in Jejunum of Lipopolysaccharide-Challenged Mice via 4D-DIA Proteomics Analysis

Identifying effective compounds to restore the polarity
of absorptive
enterocytes (AEs) holds promise for mitigating the severity and duration
of small intestinal disorders. Spermidine (SPD) is a natural polyamine;
whether it can repair inflammation-induced loss of AE polarity remains
unclear. In this study, we employed lipopolysaccharide (LPS)-challenged
mice models combined with 4D data-independent acquisition (DIA) proteomics
to investigate the mechanisms by which SPD alleviates polarity loss
in AEs. Our results demonstrated that SPD supplementation enhanced
the antioxidant capacity and improved the villus/crypt ratio in the
jejunum of LPS-treated mice. Proteomic analysis revealed that LPS
induced acute phase and inflammatory responses, significantly downregulating
the expression of cytoskeletal proteins (Pdlim3, Pdlim7) essential
for epithelial morphology as well as proteins involved in apical–basal
polarity (Pard6b, Pard3, Prkcz, LLGL2), apical membrane integrity
(Vil1, Pdims, Akp3, Tjps, Pards), and apical SLC transporters. Conversely,
SPD attenuated mucosal- and tissue-specific immune responses and reversed
the downregulation of these protein groups. Furthermore, using a Caco-2
cell model, we confirmed the anti-inflammatory effect of SPD and elucidated
its role in suppressing AE polarity loss via the regulation of HDAC4
signaling. These findings indicate that SPD effectively alleviates
the inflammation-induced loss of AE polarity in the jejunum of LPS-challenged
mice.