Interleukin-7 Dose-Dependently Restores Parenteral Nutrition–Induced Gut-Associated Lymphoid Tissue Cell Loss but Does Not Improve Intestinal Immunoglobulin A Levels

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.

Dietary Apostichopus japonicus enhances the respiratory and intestinal mucosal immunity in immunosuppressive mice

Although Apostichopus japonicus is recognized as a food and drug resource with significant immunomodulatory activity, its role in regulating the mucosal immunity remains unclear. This study aimed to explore the effects of dietary A. japonicus on mucosal immunity with an immunosuppressive mouse model. The expression of lysozyme, secretory immunoglobulin A(sIgA), and immunoglobulin A(IgA) as well as polymeric immunoglobulin receptor(pIgR) in respiratory and intestine organs was investigated. The results showed that A. japonicus could improve both the systematic and mucosal immunity. The expression of lysozyme, sIgA, and IgA in the respiratory organ was increased more significantly. Consumption of A. japonicus with the dose of 512 mg kg−1, which equals to 1/2 sea cucumber per day for adults, showed better effects. This study elucidated positive effects of A. japonicus on mucosal immunity for the first time, suggesting that moderate consumption of A. japonicus is helpful in improving mucosal immunity and preventing exogenous infection.

Nutrition and gut immunity

The human intestine contains huge amounts of nonpathologic bacteria surviving in an environment that is beneficial to both the host and the bacterial populations. When short pauses in oral intake occur with minimal alterations in the mucosa-microbial interface, critical illness, with its attendant acidosis, prolonged gastrointestinal tract starvation, exogenous antibiotics, and breakdown in mucosal defenses, renders the host vulnerable to bacterial challenge and also threatens the survival of the bacteria. This review examines the altered innate and adaptive immunologic host defenses that occur as a result of altered oral or enteral intake and/or injury.

Enteral refeeding rapidly restores PN-induced reduction of hepatic mononuclear cell number through recovery of small intestine and portal vein blood flows

BACKGROUND

Absence of enteral nutrition (EN) reduces hepatic mononuclear cell (MNC) numbers and impairs their functions. However, enteral refeeding (ER) for as little as 12 hours following parenteral nutrition (PN) rapidly restores hepatic MNC numbers. We hypothesized that changes in small intestine and portal vein blood flows related to feeding route might be responsible for this phenomenon.

METHODS

In experiment 1, mice (n = 19) were randomized to Chow (n = 5), PN (n = 7) or ER (n = 7) groups. The Chow group was given chow ad libitum with intravenous (IV) saline for 5 days. The PN group was fed parenterally for 5 days, while the ER group was re-fed with chow for 12 hours following 5 days of PN. Then, small intestine and portal vein blood flows were monitored and hepatic MNCs were isolated and counted. In experiment 2, the effects of intravenous administration of prostaglandin E(1) (PGE(1)) on hepatic MNC numbers were examined in fasted mice for 12 hours. Mice (n = 28) were randomized to Control (n = 8), PG0 (n = 10), or PG1 (n = 10) groups. The Control group was fed chow ad libitum with IV saline, while the PG0 and PG1 groups were fasted for 12 hours with infusions, respectively, of saline and PGE(1) at 1 microg/kg/minute. Blood flows and hepatic MNC numbers were examined.

RESULTS

Experiment 1: ER restored PN-induced reductions in small intestine and portal vein blood flows and hepatic MNC number to the levels in the Chow group. Small intestine and portal vein blood flows correlated positively with hepatic MNC number. Experiment 2: Fasting decreased small intestine and portal vein blood flows and hepatic MNC number. However, PGE(1) restored portal vein blood flow to the level of the Control group, and moderately increased hepatic MNC number. There was a positive correlation between portal blood flow and hepatic MNC number.

CONCLUSIONS

Reduced small intestine and portal vein blood flows may contribute to impaired hepatic immunity in the absence of EN. ER quickly restores hepatic MNC number through recovery of blood flow in both the small intestine and the portal vein.

Enteral nutrition rapidly reverses total parenteral nutrition-induced impairment of hepatic immunity in a murine model

BACKGROUND & AIMS

Total parenteral nutrition (TPN) impairs host immunocompetence, a mechanism possibly underlying the high morbidity of infectious complications in critically ill patients. Our recent study demonstrated TPN to reduce the number and function of hepatic mononuclear cells (MNCs) and to worsen survival after intraportal Pseudomonas challenge in mice. The present study examined the duration of enteral nutrition (EN) needed to reverse TPN-induced changes in hepatic MNCs in a murine model.

METHODS

Male ICR mice (6 weeks) received 5 days of TPN followed by 0 (TPN), 12 (EN12), 24 (EN24), 48 (EN48) or 72 (EN72)h of chow feeding. Control mice (Control) were given chow with intravenous saline infusions for 5 days. After nutritional support, hepatic MNCs were isolated and counted. Lipopolysaccharide (LPS) receptor expressions (CD14 and TLR4/MD2) on Kupffer cells were analyzed by flowcytometry. In addition, TPN, EN12, EN48 and control mice were given intraportal Pseudomonas challenge and survival was monitored.

RESULTS

The TPN group was significantly lower in hepatic MNC number and LPS receptor expressions than the Control group. However, EN quickly reversed TPN-induced hepatic impairments in MNC loss within 12h, CD14 expression within 48 h and TLR4/MD2 expression within 24h. Survival of the EN48 group was significantly improved as compared with the TPN and EN12 groups.

CONCLUSIONS

EN rapidly reverses TPN-induced impairment of hepatic immunity along with increased hepatic MNC numbers and LPS receptor expressions on Kupffer cells.

Fish oil infusion reverses 5-fluorouracil-induced impairments in mucosal immunity in mice

BACKGROUND & AIMS

Anticancer drugs frequently have deleterious effects on host defense against infection, limiting their clinical application. We previously demonstrated continuous infusion of 5-fluorouracil (5FU) to reduce gut associated lymphoid tissue (GALT) mass and secretory IgA levels. This study was designed to examine the effects of concomitant infusion of fish oil on gut mucosal immunity in mice receiving 5FU.

METHODS

Male ICR mice were randomized to the control (n=12), 5FU (n=12), or 5FU+FO (n=10) group. The 5FU and 5FU+FO groups received continuous IV infusion of 5FU at 10 mg/kg for 5 days. The 5FU+FO group was given a simultaneous infusion of 10 ml/kg of a 10% fish oil emulsion. The controls received normal saline at 0.3 ml/h. During these treatments, all mice were allowed free access to chow and water ad libitum. Then, the mice were sacrificed and GALT lymphocytes were isolated from Peyer's patches (PPs), the intraepithelial space (IE), and the lamina propria (LP). Small intestinal, nasal and broncho-alveolar (BALF) washings were also obtained. Lymphocyte yields from each site and phenotypes (CD4, CD8, alphabetaTCR, gammadeltaTCR, B220) were determined. IgA levels in the washings were measured with ELISA.

RESULTS

The 5FU group had significantly lower IE and LP lymphocyte numbers and small intestinal and BALF IgA levels than the control group, with no differences in the percentages of any phenotypes. However, fish oil infusion restored IE and LP lymphocyte numbers and BALF IgA to control group levels.

CONCLUSION

Fish oil infusion along with 5FU preserves GALT lymphocyte numbers and respiratory IgA levels.