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Authors Heneghan AF, Pierre JF, Kudsk KA
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Journal Ann. Surg. Volume: 258 Issue: 6 Pages: 1065-71
Publish Date 2013 Dec
PubMed ID 23160152
PMC ID 3587041
Abstract

Parenteral nutrition (PN) impairs mucosal immunity and increases the risk of infection in part via lower IgA levels at mucosal surfaces. Transport of immunoglobulin A (IgA) across the mucosa to the gut lumen depends on the epithelial transport protein, polymeric immunoglobulin receptor (pIgR), which is reduced during PN. In vitro, studies demonstrate that IL-4 up-regulates pIgR production via Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling. Because IL-4 stimulates IgA and is reduced during PN, we hypothesized that the suppressed pIgR is a result of decreased JAK-1 and STAT-6 phosphorylation. Because IL-4 is mediated by IL-25, we also hypothesized that PN + IL-25 would restore luminal IgA by increasing phosphorylated JAK-1 and STAT-6, resulting in increased tissue pIgR and luminal IgA.Experiment 1: 2 days after intravenous cannulation, male Institute of Cancer Research mice were randomized to chow (n = 11) or PN (n = 9). Experiment 2: 2 days after intravenous cannulation, male Institute of Cancer Research mice were randomized to chow (n = 12), PN (n = 10), or PN + 0.7 μg of exogenous IL-25 (n = 11) per day. After 5 days, distal ileum tissue was collected, homogenized, and protein extracted for JAK-STAT expression levels using a phospho-specific antibody microarray. Tissue was homogenized to measure pIgR expression via Western blot or fixed in 4% paraformaldehyde to measure pIgR expression via immunohistochemistry. Small intestinal wash fluid was collected and IgA was quantified using enzyme-linked immunosorbent assay.Experiment 1: PN significantly reduced phosphorylated JAK-1 and STAT-6 compared with chow. PN also decreased the tissue levels of the Th2 cytokines, IL-4 and IL-13, as well as pIgR, and luminal IgA compared with chow. Experiment 2: Exogenous administration of PN + IL-25 increased the phosphorylated JAK-1 and STAT-6 compared with PN alone. IL-25 completely restored expression of IL-13 to chow levels. IL-4, pIgR, IgA, and phosphorylated JAK-1 were significantly increased with IL-25 treatment compared with PN but failed to reach levels measured in chow. STAT-6 was significantly increased with IL-25 treatment compared with chow and PN.PN significantly decreases the JAK-STAT pathway by reducing levels of phosphorylated STAT-6 and JAK-1. Consistent with our previous work, sIgA, pIgR, and IL-4 decreased with PN, whereas the addition of IL-25 to PN reversed these decreases and demonstrated the role of the JAK-STAT pathway in vivo during PN.

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