Current aspects of mucosal immunology and its influence by nutrition

Changes of IgA and sIgA and its clinical significant in hepatic diseases

AIM: To investigate the values of IgA and sIgA detection in the clinical diagnosis of hepatic diseases.

METHODS: Patients with acute hepatitis (AH, n = 35), chronic severe hepatitis (CSH, n = 9), chronic hepatitis (CH, n = 67) and liver cirrhosis (LC, n = 57) were involved. The level of IgA was assayed by rate nephelometry, and the level of sIgA was detected by radioimmunoassay.

RESULTS: The levels of fecal IgA and sIgA were notably elevated in patients with AH, CSH, CH and LC as compared with those in the controls (IgA: 100±47, 251±178, 80±24, 145±164 mg/L vs <67 mg/L, P < 0.01; sIgA: 88±96, 326±237, 88±121, 104±109 mg/L vs 13±10 mg/L, P < 0.01). IgA was positively correlated with sIgA(r = 0.4371, P < 0.01). The levels of serum IgA and sIgA were markedly increased in patients with AH, CSH, CH and LC as compared with those in the controls (IgA: 3.1±1.1, 3.4±1.8, 3.3±1.7, 4.9±3.3 g/L vs 1.6±0.2 g/L, P < 0.01; sIgA: 31.1±25.8, 80.3±25.4, 30.5±24.1, 50.0±20.5 µg/L vs 23.4±8.2 µg/L, P<0.01 or P < 0.05). The fecal IgA and sIgA were not correlated with serum IgA and sIgA, and serum IgA was not correlated with serum sIgA (P >0.05). In patients with CH, CSH and LC, serum sIgA was significantly correlated with alkaline phosphatase (r = 0.523 0, P < 0.01) and total bilirubin (r = 0.4 581, P < 0.01). In patients with AH, serum sIgA level was correlated with alanine aminotransferase (r = 0.4 692, P < 0.01), total bilirubin (r = 0.4 265, P < 0.01).

CONCLUSION: The detection of IgA and sIgA can be used in the clinical diagnosis of hepatic diseases.

Role of Kupffer cells in lung injury in rats administered endotoxin 1

The purpose of this study was to investigate the regulation of lung macrophages (Muvarphis) by Kupffer cells (KCs) in lung injury caused by endotoxemia. Phenotypic differences in tissue Muvarphis were also investigated. Muvarphis were isolated from gadolinium chloride (GdCl(3))- or saline-treated rats 2 h after saline or lipopolysaccharide (LPS) administration. Furthermore, rats were given GdCl(3) 24 h prior to LPS administration, and survival rate was assessed for 24 h. Moreover, lung edema was assessed 9 h after LPS injection. Expression of inflammatory mediators was measured in the liver and lung. KCs were divided into three subpopulations based on size and phagocytosis. The expression of TNF-alpha and MIP-2 was greater in the small KCs and lung Muvarphis, while the expression of IL-6, IL-10, and MCP-1 was greater in the large and intermediate KCs. GdCl(3) eliminated ED2-positive large KCs and did not have any effect on the lung Muvarphis. The number of ED1-positive KCs increased significantly in both organs after LPS challenge and was reduced by GdCl(3). The population of ED2-positive KCs did not change following LPS administration. GdCl(3) completely prevented increases in lung microvascular permeability and mortality after LPS infusion. After LPS administration, expression of TNF-alpha and IL-6 increased rapidly and then decreased gradually in both organs. GdCl(3) inhibited these increases in the liver significantly and enhanced the expression of MCP-1 and IL-10 in the lung 9 h after LPS administration. Thus, the heterogeneous response of KCs to endotoxin leads to production of certain cytokines and chemokines that affect lung function.

Intestinal innate immunity: how does it relate to the pathogenesis of necrotizing enterocolitis

The pathogenesis of necrotizing enterocolitis (NEC) is poorly understood, but appears to be multifactorial and highly associated with immaturity of the gastrointestinal tract, colonization of the intestinal microbiota, and immature innate immune system. The goal of this review is to provide an overview of some of these risk factors and how they might lead to the genesis of NEC. A better understanding of these factors should help us prevent and treat this devastating disease.

Reducing costs and patient morbidity in the enterally fed intensive care unit patient

BACKGROUND

Critically ill patients are at high risk for nosocomial infections and resultant organ dysfunction and death. These patients typically have protracted intensive care unit (ICU) courses and consume increasingly limited resources. Enteral nutrition with specific immune-modulating components has been previously shown to improve outcomes in select populations of patients, but results have been mixed in critically ill patients. Impact 1.5 (Novartis Nutrition, Minneapolis, MN) is a commercially available enteral formula containing ingredients known to improve several parameters of immune function. We hypothesized that administration of Impact 1.5 tube feedings would reduce the incidence of nosocomial infection and ICU resources in critically ill patients admitted to the ICU for severe trauma, burns, or sepsis insults.

METHODS

The Impact 1.5 group (n = 17) was compared with a historical cohort of ICU patients (n = 21) of similar illness severity that received a standard high-energy enteral formula. The incidence of nosocomial infections and mortality, and the consumption of multiple ICU resources were examined. A cost analysis based on these results was then performed to determine the cost effectiveness of this proprietary immunonutrition enteral formula.

RESULTS

A pronounced reduction in nosocomial pneumonia (12% vs 52%, p < .01) was identified, with consequent trends toward a reduction in duration of mechanical ventilation and ICU length of stay. Urinary tract infections that may have less influence on ICU resources were increased in the Impact 1.5 group. No difference in mortality was identified, despite the inclusion of patients with severe sepsis in the study group. According to the average number of ICU days required for each study cohort, the Impact 1.5 group led to a cost savings of at least $193,350.00.

CONCLUSIONS

ICU patients with significant illness severity experienced a decrease in the incidence of an important nosocomial infection that is commonly associated with increased use of ICU resources and length of stay. This decrease in patient morbidity led to substantial cost savings despite the small size of our study trial.

The effects of long-term total parenteral nutrition on gut mucosal immunity in children with short bowel syndrome: a systematic review

BACKGROUND: Short bowel syndrome (SBS) is defined as the malabsorptive state that often follows massive resection of the small intestine. Most cases originate in the newborn period and result from congenital anomalies. It is associated with a high morbidity, is potentially lethal and often requires months, sometimes years, in the hospital and home on total parenteral nutrition (TPN). Long-term survival without parenteral nutrition depends upon establishing enteral nutrition and the process of intestinal adaptation through which the remaining small bowel gradually increases its absorptive capacity. The purpose of this article is to perform a descriptive systematic review of the published articles on the effects of TPN on the intestinal immune system investigating whether long-term TPN induces bacterial translocation, decreases secretory immunoglobulin A (S-IgA), impairs intestinal immunity, and changes mucosal architecture in children with SBS. METHODS: The databases of OVID, such as MEDLINE and CINAHL, Cochran Library, and Evidence-Based Medicine were searched for articles published from 1990 to 2001. Search terms were total parenteral nutrition, children, bacterial translocation, small bowel syndrome, short gut syndrome, intestinal immunity, gut permeability, sepsis, hyperglycemia, immunonutrition, glutamine, enteral tube feeding, and systematic reviews. The goal was to include all clinical studies conducted in children directly addressing the effects of TPN on gut immunity. RESULTS: A total of 13 studies were identified. These 13 studies included a total of 414 infants and children between the ages approximately 4 months to 17 years old, and 16 healthy adults as controls; and they varied in design and were conducted in several disciplines. The results were integrated into common themes. Five themes were identified: 1) sepsis, 2) impaired immune functions: In vitro studies, 3) mortality, 4) villous atrophy, 5) duration of dependency on TPN after bowel resection. CONCLUSION: Based on this exhaustive literature review, there is no direct evidence suggesting that TPN promotes bacterial overgrowth, impairs neutrophil functions, inhibits blood's bactericidal effect, causes villous atrophy, or causes to death in human model.The hypothesis relating negative effects of TPN on gut immunity remains attractive, but unproven. Enteral nutrition is cheaper, but no safer than TPN. Based on the current evidence, TPN seems to be safe and a life saving solution.

Medium-chain triglycerides enhance secretory IgA expression in rat intestine after administration of endotoxin

The purpose of this study was to determine whether medium-chain triglycerides (MCTs) modulate the inflammatory immune response to LPS and enhance the expression of secretory IgA in the rat intestine. Rats were given either corn oil or MCTs by gavage daily for 1 wk, and LPS or saline vehicle was administered via the tail vein. They were then killed, and serum and sections from the gut were collected for further analysis. Western blot analysis for secretory IgA revealed that MCTs significantly enhanced its expression in the ileum compared with corn oil in rats administered saline. After LPS challenge, expression of secretory IgA was decreased in the corn oil group but not in the MCTs group. The mRNA expression of IL-6 was assessed by real-time RT-PCR, because IL-6 regulates secretory IgA in the intestine. The expression was significantly greater in the MCTs group than in the corn oil group after LPS injection. Increases in expression of proinflammatory cytokines or chemokines such as TNF-alpha, IL-18, macrophage inflammatory protein-2, and monocyte chemoattractant protein-1 in the ileum were significantly blunted by MCTs. In addition, the mRNA expression of the Th2 IgA-stimulating cytokine IL-10 in the ileum and Peyer's patches was significantly greater in the MCTs than the corn oil group. In contrast, the mRNA expression of the Th1 IgA-inhibiting cytokine interferon-gamma was blunted by MCTs. As a result, intestinal injury was significantly reduced. Therefore, MCTs protect the gut by modulating the immune response to LPS and enhancing secretory IgA expression.

Glutamine decreases lipopolysaccharide-induced intestinal inflammation in infant rats

Using a gastrostomy-fed (GF) rat infant "pup-in-a-cup" model, the effects of protein deprivation and supplemental glutamine (Gln) and glutamate (Glu) were examined to test the hypothesis that Gln decreases the proinflammatory response induced by LPS in the developing infant rat small intestine. Four groups of 6- to 7-day-old pups were fed a rat milk substitute (RMS), one providing 100% and three providing 25% of normal protein intake for another 6 days. Two of the 25% protein-fed groups received supplemental Gln or Glu. GF and LPS treatment blunted body growth and intestinal villus height and increased intestinal cytokine-induced neutrophil chemoattractant (CINC) mRNA in the protein-deprived, non-Gln-treated group compared with mother-fed pups (P < 0.05). Gln blunted intestinal CINC mRNA (P < 0.05), but Glu did not. Intestinal CINC peptide in the LPS-treated pups provided 100 and 25% protein was elevated approximately 13-fold compared with the mother-reared pups (P < 0.001). Gln and Glu decreased intestinal CINC peptide by 73 and 80%, respectively. GF, LPS-treated pups also had a higher level of plasma CINC peptide (P < 0.05). Gln but not Glu decreased plasma CINC peptide (P < 0.05). An approximate sixfold elevation of intestinal MPO activity in the GF, LPS-treated rats was decreased by Gln and Glu by 92% (P < 0.001) and 54% (P < 0.05), respectively. Intestinal and plasma TNF-alpha were increased in GF, LPS-treated pups (P < 0.01), and Gln and Glu both blunted this increase (P < 0.05) in the intestine but not in the plasma. The results indicate that Gln decreases the LPS-induced inflammatory response in infant rat intestine under different conditions of protein intake.

Fistuloclysis can successfully replace parenteral feeding in the nutritional support of patients with enterocutaneous fistula

Background

Use of total parenteral nutrition (TPN) in patients with acute intestinal failure due to enteric fistulation might be avoided if a simpler means of nutritional support was available. The aim of this study was to determine whether feeding via an intestinal fistula (fistuloclysis) would obviate the need for TPN.

Methods

Fistuloclysis was attempted in 12 patients with jejunocutaneous or ileocutaneous fistulas with mucocutaneous continuity. Feeding was achieved by inserting a gastrostomy feeding tube into the intestine distal to the fistula. Infusion of enteral feed was increased in a stepwise manner, without reinfusion of chyme, until predicted nutritional requirements could be met by a combination of fistuloclysis and regular diet, following which TPN was withdrawn. Energy requirements and nutritional status were assessed before starting fistuloclysis and at the time of reconstructive surgery.

Results

Fistuloclysis replaced TPN entirely in 11 of 12 patients. Nutritional status was maintained for a median of 155 (range 19–422) days until reconstructive surgery could be safely undertaken in nine patients. Two patients who did not undergo surgery remained nutritionally stable over at least 9 months. TPN had to be recommenced in one patient. There were no complications associated with fistuloclysis.

Conclusion

Fistuloclysis appears to provide effective nutritional support in selected patients with enterocutaneous fistula.

Can it all be done by enteral nutrition?

PURPOSE OF REVIEW

During recent years techniques and metabolic considerations have been discussed intensively. One contributing reason is that results have not always been easy to interpret and introduce into clinical practice. Nutrition through the enteral and parenteral route has classically been compared, and this is the topic of this review.

RECENT FINDINGS

During the past 2 years a growing number of studies have focused on the amount and type of nutrition that is possible to give by enteral nutrition to intensive care unit patients. How to handle the clinical problem with paralysis and gastroparesis has also been studied. Basic research has shown a link between the gastrointestinal tract, immunocompetence and nutritional status. More evidence now exists that this is also clinically valid.

SUMMARY

Recent research has shown that enteral nutrition alone does not cover the total nutritional needs of intensive care unit patients. Enteral nutrition given early in a high dose is associated with a higher risk of complications. Metabolism in intensive care unit patients is different from the perioperative condition, which has been highlighted in recent studies with important clinical implications. The final solution has not been found yet, if it exists at all, and research in this field will continue. As the situation in biology and in real intensive care unit life is neither black nor white, it would be most beneficial for the intensive care unit patient if enteral nutrition and parenteral nutrition joined together in a good balance in order to avoid underload and overload.

Nutritional support for the burn-injured patient

The nutritional needs of the bum-injured patient are exaggerated and change constantly with the patient's stage of convalescence. Nurses working closely with other members of the health care team, specifically the nutritional specialist, can positively affect the patient's survival by optimizing the nutritional assessment,delivering enteral feedings that meet established goals,minimizing the negative consequences of hyperglycemia, and minimizing unnecessary energy expenditures by the patient. Adequate nutritional is required for wound healing, immunocompetence, and, ultimately,patient survival.

Post-pyloric enteral nutrition in septic patients: effects on hepato-splanchnic hemodynamics and energy status

OBJECTIVE

To evaluate the effects of post-pyloric enteral nutrition (EN) on hepato-splanchnic and systemic hemodynamics, metabolism and gastric mucosal energy balance in septic patients.

DESIGN

Prospective clinical study.

SETTING

Medical intensive care unit (ICU) in a university hospital.

PATIENTS

Ten hemodynamically stable, mechanically ventilated patients with severe sepsis. Eight patients required norepinephrine.

INTERVENTION

Low dose post-pyloric EN (Survimed, 40 ml bolus, 40 ml h(-1) continuously).

MEASUREMENTS AND RESULTS

Three data sets: F1 = baseline fasting, EN(120) = after 120 min of EN, F2=120 min after EN cessation. In addition to global hemodynamics and gastric mucosal PCO(2), we measured hepato-splanchnic blood flow (HSBF) using continuous primed indocyanine green dye infusion with hepatic venous sampling. The mean arterial pressure remained unchanged. During EN systemic vascular resistance decreased ( p<0.05), while cardiac index increased (p<0.001). Simultaneously, HSBF increased during EN and decreased again at F2 (1.54 [0.88; 1.66] l min(-1) m(-2 )at F1; 1.72 [1.18; 1.83] l min(-1) m(-2 )at EN and 1.38 [0.91; 1.63] l min(-1) m-(2 )at F2, p<0.001). Hepatic venous acid base status, lactate/pyruvate ratio and splanchnic lactate balance remained unchanged. There was also no change in splanchnic oxygen extraction ratio or in gastric mucosal to arterial PCO(2) difference.

CONCLUSION

The initiation of low dose post-pyloric EN in medical ICU patients with severe sepsis led to the parallel increase of systemic and hepato-splanchnic blood flow. Hepato-splanchnic energy metabolism, oxygen kinetics and gastric mucosal energy balance did not deteriorate during EN, suggesting that EN during sepsis may not be harmful even in patients requiring norepinephrine.

Total parenteral nutrition adversely affects gut barrier function in neonatal piglets

Sepsis is the most common morbidity in preterm infants, who often receive total parenteral nutrition (TPN). We hypothesized that gut barrier function is compromised in TPN-fed compared with enterally fed newborn piglets (ENT pigs). Colostrum-deprived newborn pigs were implanted with jugular venous and bladder catheters under general anesthesia. Pigs were either administered TPN (n = 15) or fed formula (ENT pigs, n = 15). After 6 days, pigs were gavaged a solution of mannitol, lactulose, and polyethylene glycol 4000 (PEG 4000) and urine was collected for 24 h. At 7 days, small bowel samples were assayed for myeloperoxidase activity, morphometry, and tight junction protein abundance. Intestinal contents and peripheral organ sites were cultured for bacteria. Urinary recovery (%dose) of mannitol (53 vs. 68) was lower, whereas that of lactulose (2.93 vs. 0.18) and PEG 4000 (12.78 vs. 0.96) were higher in TPN vs. ENT pigs, respectively (P < 0.05). Incidence of translocation was similar in TPN and ENT pigs. Myeloperoxidase activity was increased in TPN vs. ENT pigs in the jejunum (P < 0.001) and was weakly correlated with lactulose (R2 = 0.32) and PEG 4000 (R2 = 0.38) recovery. Goblet cell counts did not change, but intraepithelial lymphocyte numbers decreased with TPN. Only claudin-1 protein abundance was increased in the TPN group. We conclude that TPN is associated with impairment of neonatal gut barrier function as measured by permeability but not translocation.

Effect of route and type of nutrition on intestine-derived inflammatory responses

BACKGROUND

Immunological links between the gastrointestinal (GI) tract and respiratory tract has been postulated in the development and maintenance of mucosal immunity. Route and type of nutrition affects mucosal immunity by reducing cell populations within the Peyer's patches of the small intestine and lamina propria as well as altering cytokine profiles within these sites. In addition to the mucosal affects, these alternations in cytokines (decreases in interleukin-4 and interleukin-10) also appear to influence the vascular endothelium of the GI tract.

DATA SOURCES

This review examines the laboratory data regarding cytokine profile within the gut, endothelial adhesion molecule expression within the intestinal and extraintestinal organs, and the effect of these alterations on neutrophil accumulation and organ responses to gut ischemia/reperfusion. It also describes the effect of a specific nutrient, glutamine, on the starved gut.

CONCLUSIONS

Changes induced by failure to feed the GI tract affects GI vascularity increasing expression of proinflammatory adhesion molecules. These adhesion molecules attract neutrophils and prime them for subsequent ischemic events. Lack of feeding the gastrointestinal tract acts as a "first hit" and increases the inflammatory response to a secondary insult in the lungs, liver, and GI tract. The addition of the specific nutrient, glutamine, reverses many of these defects and favorably influences the proinflammatory effects of gut starvation.