What is the optimal lipid emulsion for preventing intestinal failure-associated liver disease following parenteral feeding in a rat model of short-bowel syndrome?

A single-day mouse mesenteric lymph surgery in mice: an updated approach to study dietary lipid absorption, chylomicron secretion, and lymphocyte dynamics

The intestine plays a crucial role in regulating whole-body lipid metabolism through its unique function of absorbing dietary fat. In the small intestine, absorptive epithelial cells emulsify hydrophobic dietary triglycerides (TAGs) prior to secreting them into mesenteric lymphatic vessels as chylomicrons. Except for short- and medium-chain fatty acids, which are directly absorbed from the intestinal lumen into portal vasculature, the only way for an animal to absorb dietary TAG is through the chylomicron/mesenteric lymphatic pathway. Isolating intestinal lipoproteins, including chylomicrons, is extremely difficult in vivo because of the dilution of postprandial lymph in the peripheral blood. In addition, once postprandial lymph enters the circulation, chylomicron TAGs are rapidly hydrolyzed. To enhance isolation of large quantities of pure postprandial chylomicrons, we have modified the Tso group's highly reproducible gold-standard double-cannulation technique in rats to enable single-day surgery and lymph collection in mice. Our technique has a significantly higher survival rate than the traditional 2-day surgical model and allows for the collection of greater than 400 μl of chylous lymph with high postprandial TAG concentrations. Using this approach, we show that after an intraduodenal lipid bolus, the mesenteric lymph contains naïve CD4+ T-cell populations that can be quantified by flow cytometry. In conclusion, this experimental approach represents a quantitative tool for determining dietary lipid absorption, intestinal lipoprotein dynamics, and mesenteric immunity. Our model may also be a powerful tool for studies of antigens, the microbiome, pharmacokinetics, and dietary compound absorption.

Intestinal failure-associated liver disease in the neonatal ICU: what we know and where we're going

PURPOSE OF REVIEW

Parenteral nutrition is an integral part of the care of infants in the neonatal ICU. However, prolonged use of parenteral nutrition can be associated with adverse outcomes, most notably parenteral nutrition-associated liver disease, now known as intestinal failure-associated liver disease (IFALD). This review highlights pertinent developments in the epidemiology of IFALD as it pertains to neonates and showcases recent advances in the pathophysiology, treatment, and outcomes of neonates with IFALD.

RECENT FINDINGS

The role of intravenous lipid emulsions in the pathogenesis, prevention, and treatment of IFALD remains a target for investigative studies. Recent data continues to support the use of fish-oil based intravenous lipids, but its use is limited due to concerns for essential fatty acid deficiency. Use of soy-based lipids and mixed lipids is not wrought with such concerns as these are often used at greater doses but their use is limited due to higher proinflammatory fatty acid content, increased phytosterols and decreased antioxidants, risk factors for the development of IFALD.

SUMMARY

Hepatic complications may limit the use of parenteral nutrition in the neonatal ICU. However, the pathophysiology of IFALD is continuing to be further elucidated and novel targets are being developed for the treatment of IFALD. As noninvasive disease monitoring strategies continue to be developed, early enteral nutrition ameliorates the risk of IFALD and should be considered when possible.