Toll-like receptor 4–dependent Kupffer cell activation and liver injury in a novel mouse model of parenteral nutrition and intestinal injury

Abstract

Infants with intestinal failure who are parenteral nutrition (PN)-dependent may develop cholestatic liver injury and cirrhosis (PN-associated liver injury: PNALI). The pathogenesis of PNALI remains incompletely understood. We hypothesized that intestinal injury with increased intestinal permeability combined with administration of PN promotes LPS-TLR4 signaling dependent Kupffer cell activation as an early event in the pathogenesis of PNALI. We developed a mouse model in which intestinal injury and increased permeability were induced by oral treatment for 4 days with dextran sulphate sodium (DSS) followed by continuous infusion of soy lipid-based PN solution through a central venous catheter for 7 (PN/DSS7d) and 28 (PN/DSS28d) days. Liver injury and cholestasis were evaluated by serum AST, ALT, bile acids, total bilirubin, and by histology. Purified Kupffer cells were probed for transcription of pro-inflammatory cytokines. PN/DSS7d mice showed elevated portal vein LPS levels, evidence of hepatocyte injury and cholestasis, and increased Kupffer cell expression of IL6, TNFα, and TGFβ. Serological markers of liver injury remained elevated in PN/DSS28d mice associated with focal inflammation, hepatocyte apoptosis, peliosis, and Kupffer cell hypertrophy and hyperplasia. PN infusion without DSS pre-treatment or DSS pre-treatment alone did not result in liver injury or Kupffer cell activation. Suppression of the intestinal microbiota with broad spectrum antibiotics or ablation of TLR4 signaling in TLR4 mutant mice resulted in significantly reduced Kupffer cell activation and markedly attenuated liver injury in PN/DSS7d mice. Conclusion These data suggest that intestinal-derived LPS activates Kupffer cells through TLR4 signaling in early stages of PNALI.

Raw bovine milk improves gut responses to feeding relative to infant formula in preterm piglets

“…The increased villus atrophy and permeability may enhance the invasion of bacteria and toxins via paracellular routes, or even translocation to the blood stream, leading to later inflammation, infection, and sepsis during this extended experimental period. The increased liver weight in IF-fed pigs in both studies may also imply hepatic inflammation related to elevated intestinal permeability (13,17).…”

Features of liver tissue remodeling in intestinal failure during and after weaning off parenteral nutrition

“…9,10 In mice, the combination of PN and lipopolysaccharide translocation induced by intestinal injury synergistically activates Kupffer cell expression of proinflammatory cytokines and fibrogenic growth factors. 4,5 In accordance with experimental studies, PN-dependent children with IF display an overabundance of lipopolysaccharideproducing Proteobacteria in their intestinal microbiota in association with histologic liver injury, intestinal inflammation, and increased levels of serum proinflammatory cytokines. 11 Liver fibrosis is observed with increasing frequency after extensive distal small intestinal resection in children 6,8 and even without a history of PN administration in pigs, 12 supporting an essential role of disturbed intestinal homeostasis in the pathogenesis of IFALD.…”

“…In general, these findings point to a greater activity of liver fibrogenesis when IFassociated intestinal compromise was combined with PN, supporting their synergistic role in the pathogenesis of IFALD 13,27 in accordance with experimental findings. 5 Our study had some limitations. In addition to the limited number of patients, the cross-sectional design provides associations rather than proven causal relationships between different study variables.…”

“…Administration of PN and impaired intestinal barrier function are required for development of cholestatic liver injury in mice. 5 In this novel mouse model, pharmacologically induced intestinal barrier dysfunction in intact intestine leads to lipopolysaccharide translocation to the portal vein, which in combination with PN containing the plant sterol (stigmasterol), activates Kupffer cell expression of the proinflammatory cytokines IL-1, IL-6, and TNFa and the profibrotic TGFb through toll-like receptor 4 signaling. 4,5 These mechanisms may be translatable to IFALD observed in humans.…”

Parenteral Nutrition-Associated Liver Disease in Pediatric Patients: Strategies for Treatment and Prevention

“…Figure 17.1 shows a schematic concept of this theoretical mechanism driving the development of PNALD. Potentially, the use of broad-spectrum antibiotics to suppress the intestinal microfl ora or the ablation of TLR4 signaling may attenuate this liver injury [ 37 ]. Combined small bowel atrophy, decreased intestinal immunoglobulin A (IgA) levels, production of hepatotoxic cytokines, and disruption of the intestinal microfl ora and bacterial overgrowth all may occur as a result of bowel rest.…”