The effect of adding fish oil to parenteral nutrition on hepatic mononuclear cell function and survival after intraportal bacterial challenge in mice

Lipid Compositions of Total Parenteral Nutrition Affect Gut Peyer's Patches and Morphology in Mice

INTRODUCTION

Although parenteral nutrition (PN) is the only option for providing adequate nutrition to patients who cannot tolerate oral ingestion, it severely impairs intestinal barrier function in terms of morphology and immunity. While addition of either soybean oil (SO) or fish oil (FO) to PN partially reverses these defects, the effects of the oil composition (FO/SO ratio) on morphology and gut-associated lymphoid tissues (GALT) have yet to be elucidated. We focused on the effects of the FO/SO ratio in PN on the number of lymphocytes in Peyer's patches, immunoglobulin A levels, and intestinal structures.

METHODS

Male ICR mice (n = 61) were randomized into five groups; oral nutrition (Chow, n = 14) and four groups receiving PN without oral nutrition. PN solutions contained fat emulsions with the following FO:SO ratios: 0:1 (SO, n = 12), 1:11.5 (11.5FSO, n = 17),1:2 (1:2FSO, n = 13) and 1:0 (FO, n = 5). All mice underwent jugular vein catheter insertion. The PN groups were given isocaloric and isonitrogenous nutritional support with 20% of total calories from fat emulsions with equivalent fat delivery in 11.9 g/kg/d. After 5 d of each feeding, Peyer's patches lymphocytes were isolated from the small intestine, counted and analyzed with flowcytometry for determination of their phenotypes (αβTCR+, γδTCR+, CD4+, CD8+ and B cells). Villus height and crypt depth of the jejunum and ileum were evaluated with hematoxylin-eosin staining. Immunoglobulin A levels in the intestinal washings were also determined.

RESULTS

Numbers of total lymphocytes and B lymphocytes in PP were increased in the 1:2 FSO-PN but neither in the 1:11.5 FSO nor the FO group, as compared to the SO group. There were no marked differences among the groups in numbers neither of total T cells nor in any of T cell phenotypes determined. The 1:2 FSO group showed significantly greater villus height and crypt depth than the SO group. IgA levels did not differ significantly among the four PN groups.

CONCLUSIONS

The PN with 1:2 FSO (FO:SO = 1:2) maintained lymphocyte numbers in PP and intestinal villus morphology at levels nearly the same as those obtained with chow feeding. An appropriate ratio of FO to SO in PN is expected to prevent immunological impairment and morphological atrophy of the gut associated with lack of oral nutrition.

The influence of dietary restriction on hepatic mononuclear cell numbers and functions in mice

BACKGROUND

Surgical patients with gastrointestinal malignancies are at increased risk for malnutrition. However, the mechanism by which dietary restriction (DR), one form of malnutrition, impairs hepatic immunity remains to be clarified. The present study was designed to examine the influence of DR on hepatic mononuclear cell (MNC) numbers, subpopulations, and cytokine productions (tumor necrosis factor α [TNF-α], interferon gamma [IFN-γ], and interleukin 10 [IL-10]) in response to lipopolysaccharide (LPS) in mice. Immunoglobulin (Ig) A levels in the gallbladder and histopathologic changes in the liver were also assessed.

MATERIAL AND METHODS

Male Institute of Cancer Research mice were randomly assigned to three dietary groups: ad libitum (AD), mild restriction (MR), and severe restriction (SR). The AD, MR, and SR groups received daily mouse chow in amounts of 190, 133, and 76 g/kg, respectively, for 7 d. After the mice had been fed for 7 d, hepatic MNCs were isolated. Total hepatic MNCs were counted and subpopulations were determined by flow cytometry. Cytokine productions (TNF-α, IFN-γ, and IL-10) by hepatic MNCs in response to LPS were measured. Blood samples were analyzed for hepatobiliary biochemical parameters. IgA levels in gallbladder bile were measured with enzyme-linked immunosorbent assay. In addition, liver histologies were examined.

RESULTS

Hepatic MNC numbers were significantly lower in the MR and SR groups than in the AD group, with no significant difference between the MR and SR groups. The percentage of B cells was significantly lower in the SR group than in the MR and AD groups, whereas the T-cell percentage was higher in the SR group than in the MR and AD groups. The percentage of Kupffer cells was significantly lower in the SR group than in the AD group, whereas that in the MR group was midway between those in the SR and AD groups. TNF-α and IL-10 levels in hepatic MNC culture supernatants were increased LPS-dose dependently in the AD group. However, the increase was slight in the MR group and absent in the SR group. The IgA levels in gallbladder bile were significantly lower in the SR and MR groups than in the AD group. On the basis of hematoxylin and eosin staining of hepatic sections, livers from the SR group showed atrophic hepatocytes and sinusoidal dilatation, whereas these changes were absent in the AD group.

CONCLUSIONS

DR decreases hepatic MNC number with subpopulation changes, reduces IgA levels in gallbladder bile, blunts cytokine production by hepatic MNCs, and induces pathologic damage in the liver, which may be an important mechanism underlying the impaired host defense associated with malnutrition.

Influence of fish to soybean oil ratio on hepatic mononuclear cell function and survival after intraportal bacterial challenge in parenterally fed mice

BACKGROUND

Parenteral nutrition (PN) is indispensable for meeting the caloric and substrate needs of patients who cannot receive adequate amounts of enteral nutrition. However, PN decreases hepatic mononuclear cell (MNC) numbers and impairs their functions. We examined the effects of various ratios of ω-3 to ω-6 polyunsaturated fatty acids on hepatic MNC number and function in a murine model. We focused on serum liver enzymes, lipid metabolism, cytokine production, histopathology, and the outcomes of an intraportal bacterial challenge.

MATERIAL AND METHODS

In experiment 1, male Institute of Cancer Research mice were randomized to CHOW, 67%, 33%, 16%, 8%, 4%, and 0% fish oil (FO)-PN groups. After receiving their respective diets for 5 days, 1.0 × 10(7) Pseudomonas aeruginosa were delivered by intraportal injection. Survival was observed ≤ 7 days after injection. Liver histologies after intraportal bacterial challenge were examined in the CHOW, 33%, 8%, and 0% FO-PN groups. In experiment 2, the mice were divided into 4 groups: CHOW, 33%, 8%, and 0% FO-PN. After the mice had been fed for 5 days, MNC were isolated. Hepatic MNC were counted and cytokine productions (tumor necrosis factor [TNF]-α and interleukin [IL]-10) by MNC in response to lipopolysaccharide (LPS) were measured. Blood samples were analyzed for lipid metabolism and hepatobiliary biochemical parameters. Liver histologies were also examined.

RESULTS

In experiment 1, survival times were significantly shorter in the 4% and 0% FO-PN groups than in the CHOW group. Survival rates at 168 hours were 100%, 64%, 86%, 73%, 67%, 11%, and 13% in the CHOW, 67%, 33%, 16%, 8%, 4%, and 0% FO-PN groups, respectively. At 72 hours after intraportal bacterial challenge, the 0% FO-PN group showed severe tissue damage, whereas such damage was reduced in the 8% and 33% FO-PN groups. In experiment 2, the CHOW, 33%, 8%, and 0% FO-PN groups showed LPS dose-dependent increases in TNF-α levels. IL-10 levels were also LPS dose-dependently increased in the CHOW and 33% FO-PN groups. However, no marked changes were observed in response to LPS stimulation in either the 8% or the 0% FO-PN group. There were no differences in serum levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, or total bilirubin among these 4 groups. In the 0% FO-PN group, serum total cholesterol levels were greater than those in the 8% and 33% FO-PN groups. Without bacterial challenge, livers from the 0% FO-PN group showed steatosis, but these changes were attenuated in the 8% and 33% FO-PN groups.

CONCLUSION

The 30-40% ratio of FO to soybean oil with 20% of total calories supplied by lipid seems to be the best PN for preservation of hepatic MNC number and function.