Small intestine mucosal immune system response to injury and the impact of parenteral nutrition

Modulation of gut-microbiota through probiotics and dietary interventions to improve host health

Dietary patterns play an important role in regards to the modulation and control of the gut microbiome composition and function. The interaction between diet and microbiota plays an important role in order to maintain intestinal homeostasis, which ultimately affect the host's health. Diet directly impacts the microbes that inhabit the gastrointestinal tract (GIT), which then contributes to the production of secondary metabolites, such as short-chain fatty acids, neurotransmitters, and antimicrobial peptides. Dietary consumption with genetically modified probiotics can be the best vaccine delivery vector and protect cells from various illnesses. A holistic approach to disease prevention, treatment, and management takes these intrinsically linked diet-microbes, microbe-microbe interactions, and microbe-host interactions into account. Dietary components, such as fiber can modulate beneficial gut microbiota, and they have resulting ameliorative effects against metabolic disorders. Medical interventions, such as antibiotic drugs can conversely have detrimental effects on gut microbiota by disputing the balance between Bacteroides and firmicute, which contribute to continuing disease states. We summarize the known effects of various dietary components, such as fibers, carbohydrates, fatty acids, vitamins, minerals, proteins, phenolic acids, and antibiotics on the composition of the gut microbiota in this article in addition to the beneficial effect of genetically modified probiotics and consequentially their role in regards to shaping human health. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Probiotics (Lactobacillus plantarum HNU082) Supplementation Relieves Ulcerative Colitis by Affecting Intestinal Barrier Functions, Immunity-Related Gene Expression, Gut Microbiota, and Metabolic Pathways in Mice

Probiotics can effectively improve ulcerative colitis (UC), but the mechanism is still unclear. Here, shotgun metagenome and transcriptome analyses were performed to explore the therapeutic effect and the mechanism of the probiotic Lactobacillus plantarum HNU082 (Lp082) on UC. The results showed that Lp082 treatment significantly ameliorated dextran sulfate sodium (DSS)-induced UC in mice, which was manifested as increases in body weight, water intake, food intake, and colon length and decreases in disease activity index (DAI), immune organ index, inflammatory factors, and histopathological scores after Lp082 intake. An in-depth study discovered that Lp082 could improve the intestinal mucosal barrier and relieve inflammation by cooptimizing the biological barrier, chemical barrier, mechanical barrier, and immune barrier. Specifically, Lp082 rebuilt the biological barrier by regulating the intestinal microbiome and increasing the production of short-chain fatty acids (SCFAs). Lp082 improved the chemical barrier by reducing intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM) and increasing goblet cells and mucin2. Lp082 ameliorated the mechanical barrier by increasing zonula occludens-1 (ZO-1), zonula occludens-2 (ZO-2), and occludin while decreasing claudin-1 and claudin-2. Lp082 optimized the immune barrier by reducing the content of interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α), myeloperoxidase (MPO), and interferon-γ (IFN-γ) and increasing IL-10, transforming growth factor-β1 (TGF-β1), and TGF-β2, inhibiting the NF-κB signaling pathway. Taken together, probiotic Lp082 can play a protective role in a DSS-induced colitis mouse model by protecting the intestinal mucosal barrier, attenuating the inflammatory response, and regulating microbial imbalance. This study provides support for the development of probiotic-based microbial products as an alternative treatment strategy for UC. IMPORTANCE Many studies have focused on the therapeutic effect of probiotics on ulcerative colitis (UC), but few studies have paid attention to the mechanism of probiotics, especially the therapeutic effect. This study suggests that Lp082 has a therapeutic effect on colitis in mice. Its mechanisms of action include protecting the mucosal barrier and actively modulating the gut microbiome, modulating inflammatory pathways, and reducing neutrophil infiltration. Our study enriches the mechanism and provides a new prospect for probiotics in the treatment of colitis, helps to deepen the understanding of the intestinal mucosal barrier, and provides guidance for the future probiotic treatment of human colitis.

The Pathology and Physiology of Ileostomy

An ileostomy is a surgery that is commonly performed to protect low pelvic anastomoses or prevent high-risk anastomotic leakages. However, various postoperative complications remain of major concern. After an ileostomy, the distal intestinal segment is left open for an extended period and is in a non-functional state. Consequently, the intestinal mucosa, smooth muscle, and microbiota undergo significant changes that are closely related to postoperative recovery and complications. A systematic description of these changes is necessary to understand the relationship among them and take more effective measures for postoperative intervention.

The effect of enteral stimulation on the immune response of the intestinal mucosa and its application in nutritional support

The intestine plays a fundamental role as a regulator of the mucosal immune response, mostly through the production and secretion of secretory Immunoglobulin A (sIgA) by the gut-associated lymphoid tissue (GALT). Enteral stimulation, a balance between the commensal microbiota and pathogenic microorganisms, in addition to an adequate nutritional status is required for the optimal immune function of the intestine. Fasting subjects or those supported only with parenteral nutrition, show a progressive anatomical and physiological deterioration of the GALT, triggering a series of alterations resulting in a decrease in the intestinal immune response, modification in the type of microbiota, and changes that lead to or aggravate malnutrition. Patients with malnutrition present an increase in the rate of nosocomial infections, hospital length of stay, and mortality. An adequate nutritional assessment at hospital admission and avoiding long periods of fasting are paramount to prevent these unfavorable outcomes. Herein, we present a mini-state of the art review on the role and importance of enteral stimulation by GALT-mediated immune response.

Impact of early protein provision on the mortality of acute critically ill stroke patients

BACKGROUND

Stroke is the leading cause of death in China, and dysphagia is a common symptom of stroke. For acute critically ill stroke patients, whether the protein provision overwhelming calorie provision impacts the outcome still requires investigation.

MATERIALS AND METHODS

We conducted a retrospectively observational study. Acute stroke patients admitted to our neurocritical care unit between January 2013 and January 2017 were enrolled. Primary end points were short-term (30-day) and long-term (6-month) mortality, as well as long-term poor outcome with a modified Rankin scale score ≥4.

RESULTS

Of 208 eligible patients, 127 (61.1%) patients were diagnosed with acute ischemic stroke and 81 (38.9%) with intracranial hemorrhage. In multivariate logistic regression analysis, the increased protein provision was significantly associated with reduced 30-day and 6-month mortality (P = .041 and P = .020, respectively) but not 6-month functional outcome (P = .365), whereas calorie provision had no independent association with either mortality or functional outcome. When the protein provision ≤1.74 g/kg/day, there was a 9.37% decrease in short-term mortality and a 9.21% decrease in long-term mortality with each 0.1 g/kg/day increase in protein delivery. The patients were further divided into five subgroups based on the amount of protein provision, and Linear-by-Linear Association tests showed there was a negative linear relationship between the protein provision and 30-day and 6-month mortality (P = .048 and P = .017, respectively).

CONCLUSIONS

Early protein provision during the first week is an independent predictor of short-term and long-term mortality in acute critically ill stroke patients.

Influences of Short-Term Fasting and Carbohydrate Supplementation on Gut Immunity and Mucosal Morphology in Mice

BACKGROUND

Preoperative carbohydrate (CHO) supplementation has been recommended in enhanced recovery after surgery protocols. However, the effects of CHO supplementation on gut and systemic immunity are not well understood.

METHODS

Mice (n = 60) were randomized to 1 of the following 5 groups: control (ad lib feeding), 12-hour fasting without CHO administration (fasting), and 12 hours of fasting with CHO administration at 2, 4, and 8 hours before sacrifice. Then, lymphocytes were isolated from gut-associated lymphoid tissue, that is, Peyer's patches, the intraepithelial space, and the lamina propria of the small intestine. These lymphocyte numbers and phenotypes were evaluated. IgA levels in respiratory and small-intestinal washings were determined by ELISA. Morphology, proliferation, and apoptosis of the intestinal epithelium were also evaluated histologically.

RESULTS

Although there were no significant differences in IgA levels among the 5 groups, fasting decreased intraepithelial and lamina propria, but not Peyer's patches lymphocyte numbers. CHO at 2 hours prevented lymphocyte loss in intraepithelial, whereas CHO at 4 hours reversed lamina propria lymphocytes numbers. Percentages of lymphocyte phenotypes were similar in each site among the 5 groups. Fasting caused villous atrophy; however, CHO at 2 hours restored villous structure along with maintenance of epithelial cell proliferation rate.

CONCLUSIONS

Only 12 hours of fasting causes marked gut-associated lymphoid tissue cell loss along with gut atrophy. However, CHO at 2 hours preserves gut immunity and morphology not completely but moderately.

Chronic Critical Illness and Persistent Inflammation: What can we Learn from the Elderly, Injured, Septic, and Malnourished?

Patients in the intensive care unit (ICU) who develop chronic critical illness significantly stress the clinical capacity and financial resources of healthcare systems. Although vast improvements have been made in critical care management, outcomes for this ICU subset remain poor. A hallmark for patients who progress to chronic critical illness is the development of persistent inflammation and immunosuppression. The risk factors associated with the development of chronic critical illness include increased age, medical comorbidities, severe injury, septic shock, and malnutrition. Interestingly, each of these clinical states bears strikingly similar immune defects, often resulting in the activation of a persistent inflammatory state. Strategies aimed at the prevention or early recognition of this state of immune compromise may help improve outcomes for these individuals and minimize the number who progress to chronic critical illness. This review explores the current knowledge regarding the immune defects associated with the development of persistent inflammation, the ways in which it can manifest clinically, attempted therapeutic interventions to date, and future insights into improving outcomes for this patient population.

Effect of early fasting and total parenteral nutrition support on the healing of incision and nutritional status in patients after sacrectomy

INTRODUCTION

Surgical site infection is one of the most common complications for patients after sacrectomy, which often accompanied by poor wound healing, sinus formation and serious metabolic disturbance.

HYPOTHESIS

We tried to avoid the surgical site infection caused by feces during early period after surgery through early fasting and total parenteral nutrition (TPN) support, then compared the clinical results of these patients with other patients that received enteral nutrition (EN) early after sacrectomy.

METHODS

Forty-eight patients after sacrectomy (the level of sacrectomy above S₂) were randomly divided into two groups: TPN group and EN group. The patients of two groups received different nutrition support from the first day to the seventh day after surgery, then the factors such as nutritional and metabolic status after surgery, incidence of complications as well as the time of incision healing and hospitalization were observed.

RESULTS

The p-value of total serum protein, albumin, serum alanine aminotransferase, total bilirubin at seventh day after sacrectomy between TPN group and EN group is <0.0005. The p-value of hemoglobin at seventh day after sacrectomy between TPN group and EN group is 0.001. The p-value of total serum protein at fourteenth day after sacrectomy between TPN group and EN group is 0.003. The p-value of albumin and total bilirubin at fourteenth day after sacrectomy between TPN group and EN group is 0.001. The p-value of hemoglobin, serum alanine aminotransferase at fourteenth day after sacrectomy between TPN group and EN group is <0.0005. The incidence of gastrointestinal complication and delay of apparition of feces in EN group were lower than that in TPN group (p=0.041, p<0.0005). The incidence of surgical site infection, the time of incision healing and hospitalization in TPN group were lower than that in EN group (p=0.048, p=0.008, p<0.0005).

CONCLUSIONS

The method of fasting and supported by TPN during the early period after sacrectomy contribute to the incision healing, meanwhile, it shortens the hospitalization time and abates the incidence of complications in patients after sacrectomy.

TYPE OF STUDY

It is a comparative randomized study.

LEVEL OF PROOF

High-powered prospective randomized trial.

Apigenin ameliorates vascular injury in rats with high fructose-induced metabolic disturbance by inhibiting PI3K/AKT/GLUT1

The abuse of fructose in daily diet may cause cardiovascular diseases that seriously threaten human health, and both safe and efficient solutions need to be developed. We investigated whether apigenin can prevent the harmful impact of excessive fructose on cardiovascular events. Based on the reduction of percentage of body fat and systolic pressure as well as the improvements in insulin resistance, lipid metabolism, and pathological injury to the thoracic aorta, we suggested that high levels of fructose cause vascular injury and metabolic disorders, which can be improved to some extent by using apigenin. Fundamentally, apigenin down-regulates levels of phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), and glucose transporter 1 (GLUT1), which increase with high concentrations of fructose. Moreover, the inflammation and asymmetric dimethylarginine (ADMA) levels increased in fructose group, but they decreased when the rats were fed with apigenin. The results suggest that PI3K/AKT/GLUT1 may have potential for alleviating cardiovascular injury, and apigenin can be an excellent candidate for supplements to ameliorate cardiovascular diseases related to high fructose consumption.

(A) Chemical structure of apigenin. (B) Graph illuminating the experimental design for the time course of fructose and apigenin administration, and the timelines for the histological studies, biochemical analysis and western blot analysis.

Partial enteral nutrition increases intestinal sIgA levels in mice undergoing parenteral nutrition in a dose-dependent manner

BACKGROUND AND AIMS

Partial enteral nutrition (PEN) protects parenteral nutrition (PN) induced gut mucosal immunity impairment. However, the gastrointestinal function of most patients with PN is too poor to tolerate full dosage of PEN and no guidelines recommend PEN dose. We aimed to identify an optimal PEN dose and to understand the protective mechanism.

METHODS

Mice were assigned to groups with total parenteral nutrition (TPN), total enteral nutrition (TEN), or various degrees of PEN with PN. Additionally, AS1517499 was used to inhibit STAT6. Five days after treatment, secretory immunoglobulin A (sIgA) levels of luminal washing fluid and JAK1-STAT6 signalling in ileum tissue of different groups were assessed.

RESULTS

We found that TPN lowered luminal sIgA and down-regulated pIgR, phosphorylated JAK1 and STAT6, IL-4 and IL-13 as well relative to TEN. Moreover, 40% EN were lowest dose that reversed these detrimental consequences of PN to an equivalent level as TEN. The rescue of pIgR and luminal sIgA expression was decreased when the JAK1-STAT6 pathway was inhibited.

CONCLUSION

We conclude that 40% EN is the optimal PEN dose that reverses PN-induced impairment of gut mucosal immunity. Additionally, we hypothesise that this benefit involves activation of the JAK1-STAT6 pathway.

Gastrointestinal immune and microbiome changes during parenteral nutrition

Parenteral nutrition (PN) is a lifesaving therapy that provides intravenous nutrition support to patients who cannot, or should not, feed via the gastrointestinal (GI) tract. Unfortunately, PN also carries certain risks related to infection and metabolic complications compared with enteral nutrition. In this review, an overview of PN and GI immune and microbiome changes is provided. PN impacts the gut-associated lymphoid tissue functions, especially adaptive immune cells, changes the intestinal epithelium and chemical secretions, and significantly alters the intestinal microbiome. Collectively, these changes functionally result in increased susceptibility to infectious and injurious challenge. Since PN remains necessary in large numbers of patients, the search to improve outcomes by stimulating GI immune function during PN remains of interest. This review closes by describing recent advances in using enteric nervous system neuropeptides or microbially derived products during PN, which may improve GI parameters by maintaining immunity and physiology.

Advances in research of intestinal bacterial translocation

Intestinal bacterial translocation occurs in a variety of pathological conditions, especially for patients with severe diseases. Intestinal bacterial translocation can cause enterogenic infection and end with multiple organ dysfunction syndrome (MODS). Inflammation often origins from endogenous infection and endotoxemia caused by intestinal bacteria and their endotoxins. In MODS, the intestine is not only the initiating organ but also the target one. More and more studies show that intestinal bacterial translocation plays an important role in the development of intestinal diseases such as liver disease and acute pancreatitis. Early diagnosis, interference and prevention of bacterial translocation can be a novel way or a crucial step in the treatment of a variety of diseases. This review aims to elucidate the association between intestinal bacterial translocation and parenteral diseases as well as their pathogenesis, prevention, and detection.

Parenteral glutamine supplementation in combination with enteral nutrition improves intestinal immunity in septic rats

OBJECTIVES

The gut-associated lymphoid tissue is continuously exposed to antigens in the gut lumen and becomes the first line of defense against enteric bacteria and associated toxin. The aim of this study was to investigate the effects of parenteral glutamine (GLN) supplementation in combination with enteral nutrition (EN) on intestinal mucosal immunity in septic rats by cecal ligation and puncture (CLP).

METHODS

Male Sprague-Dawley rats were randomly assigned into four groups: A sham CLP + EN + saline group (n = 10), a sham CLP + EN + GLN group (n = 10), a CLP + EN + saline group (n = 10), and a CLP + EN + GLN group (n = 10). At 2 h after CLP or sham CLP, all rats in each of the four groups received an identical enteral nutrition solution as their base formula. Then, the rats in the sham CLP + EN + GLN group and CLP + EN + GLN group were given 0.35 g GLN/kg body weight daily for 7 d, all at the same time, via a tail vein injection; whereas those in the sham CLP + EN + saline group and CLP + EN + saline group were daily administered isovolumic sterile 0.9% saline for comparison. All rats in each of the four groups were given 290 kcal/kg body wt/d for 7 d. At the end of the seventh day after the nutritional program was finished, all rats were euthanized and the entire intestine was collected. Total Peyer's patches (PP) cell yield was counted by a hemocytometer. The percentage of PP lymphocyte subsets was analyzed by flow cytometry. The number of intestinal lamina propria IgA plasma cells was determined by the immunohistochemistry technique. The intestinal immunoglobulin A (IgA) levels were assessed by ELISA. PP apoptosis was evaluated by terminal deoxyuridine nick-end labeling.

RESULTS

The results revealed total PP cell yield, the numbers of PP lymphocyte subsets, intestinal lamina propria IgA plasma cells, and intestinal IgA levels in the CLP + EN + GLN group were significantly increased when compared with the CLP + EN + saline group (P < 0.05). On the other hand, the number of TUNEL-stained cells within PPs in the CLP + EN + GLN group was markedly decreased as compared with the CLP + EN + saline group (P < 0.05).

CONCLUSION

The results of this study show that parenteral glutamine supplementation in combination with enteral nutrition may attenuate PP apoptosis, increase PP cell yield and intestinal lamina propria IgA plasma cells, and subsequently improve intestinal mucosal immunity. Clinically, these results suggest therapeutic efforts at improving intestinal immunity may contribute to the prevention and treatment of sepsis.

Innate Mucosal Immune System Response of BALB/c vs C57BL/6 Mice to Injury in the Setting of Enteral and Parenteral Feeding

BACKGROUND

Outbred mice exhibit increased airway and intestinal immunoglobulin A (IgA) following injury when fed normal chow, consistent with humans. Parenteral nutrition (PN) eliminates IgA increases at both sites. Inbred mice are needed for detailed immunological studies; however, specific strains have not been evaluated for this purpose. BALB/c and C57BL/6 are common inbred mouse strains but demonstrate divergent immune responses to analogous stress. This study addressed which inbred mouse strain best replicates the outbred mouse and human immune response to injury.

METHODS

Intravenously cannulated mice received chow or PN for 5 days and then underwent sacrifice at 0 or 8 hours following controlled surgical injury (BALB/c: n = 16-21/group; C57BL/6: n = 12-15/group). Bronchoalveolar lavage (BAL) was analyzed by enzyme-linked immunosorbent assay for IgA, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6, while small intestinal wash fluid (SIWF) was analyzed for IgA.

RESULTS

No significant increase in BAL IgA occurred following injury in chow- or PN-fed BALB/c mice (chow: P = .1; PN: P = .7) despite significant increases in BAL TNF-α and SIWF IgA (chow: 264 ± 28 vs 548 ± 37, P < .0001; PN: 150 ± 12 vs 301 ± 17, P < .0001). Injury significantly increased mucosal IgA in chow-fed C57BL/6 mice (BAL: 149 ± 33 vs 342 ± 87, P = .01; SIWF: 236 ± 28 vs 335 ± 32, P = .006) and BAL cytokines. After injury, PN-fed C57BL/6 mice exhibited no difference in BAL IgA (P = .9), BAL cytokines, or SIWF IgA (P = .1).

CONCLUSIONS

C57BL/6 mice exhibit similar airway responses to injury as outbred mice and humans, providing an appropriate model for studying mucosal responses to injury. The BALB/c mucosal immune system responds differently to injury and does not replicate the human injury response.

Effect of diclazuril on intestinal morphology and SIgA expression in chicken infected with Eimeria tenella

Secretory immunoglobulin A (SIgA), as a vital actor involving in the mucosal immunity, plays a key role in defending a variety of pathogenic infections, such as bacteria, viruses and parasites. Eimeria tenella is an obligate intracellular apicomplexan parasite contacting with the digestive tract mucosa and specially parasitizes chicken caecum, causing a severe form of coccidiosis. Coccidiosis is currently mainly controlled using chemotherapeutic agents. Diclazuril, a classic coccidiostat, was used widely in the poultry industry. Because of the rising problem of drug resistance, it is therefore crucial to understand the pattern of the SIgA expression in the action of diclazuril against E. tenella. In this study, the intestinal morphology in the caecum was analyzed by haematoxylin-eosin (HE) staining, and the SIgA expression was examined by immunohistochemical technique. At the same time, the duodenum, jejunum and ileum tissues have also been evaluated. HE staining results showed that E. tenella infection caused severe damage characterized by structural disorder, haemorrhage, inflammatory cell infiltration, serous and fibrinous exudation in chicken caecum and invisible damage in the duodenum, jejunum and ileum. With the treatment of diclazuril, the damage in the caecum was alleviated obviously. Immunohistochemical analysis demonstrated that the SIgA level in the infected group was increased in the duodenum (p < 0.05), jejunum and ileum, respectively, but decreased (p < 0.01) in the caecum, compared with the control group. Interestingly, the SIgA level was decreased in the duodenum (p < 0.05), jejunum and ileum but increased (p < 0.05) in the caecum in the infected/diclazuril group in comparison to the infected group. The results showed that diclazuril effectively alleviated the damage in the caecum induced by E. tenella and provided a cure for coccidiosis by improving the immune function in chickens.

Tumour necrosis factor--induced loss of intestinal barrier function requires TNFR1 and TNFR2 signalling in a mouse model of total parenteral nutrition

Tumour necrosis factor-α (TNF-α) has been reported to play a central role in intestinal barrier dysfunction in many diseases; however, the precise role of the TNF-α receptors (TNFRs) has not been well defined using in vivo models. Our previous data showed that enteral nutrient deprivation or total parenteral nutrition (TPN) led to a loss of intestinal epithelial barrier function (EBF), with an associated upregulation of TNF-α and TNFR1. In this study, we hypothesized that TNF-α plays an important role in TPN-associated EBF dysfunction. Using a mouse TPN model, we explored the relative roles of TNFR1 vs. TNFR2 in mediating this barrier loss. C57/BL6 mice underwent intravenous cannulation and were given enteral nutrition or TPN for 7 days. Tumour necrosis factor-α receptor knockout (KO) mice, including TNFR1KO, TNFR2KO or TNFR1R2 double KO (DKO), were used. Outcomes included small intestine transepithelial resistance (TER) and tracer permeability, junctional protein zonula occludens-1, occludin, claudins and E-cadherin expression. In order to address the dependence of EBF on TNF-α further, exogenous TNF-α and pharmacological blockade of TNF-α (Etanercept) were also performed. Total parenteral nutrition led to a loss of EBF, and this was almost completely prevented in TNFR1R2DKO mice and partly prevented in TNFR1KO mice but not in TNFR2KO mice. The TPN-associated downregulation of junctional protein expression and junctional assembly was almost completely prevented in the TNFR1R2DKO group. Blockade of TNF-α also prevented dysfunction of the EBF and junctional protein losses in mice undergoing TPN. Administration of TPN upregulated the downstream nuclear factor-B and myosin light-chain kinase (MLCK) signalling, and these changes were almost completely prevented in TNFR1R2DKO mice, as well as with TNF-α blockade, but not in TNFR1KO or TNFR2KO TPN groups. Tumour necrosis factor-α is a critical factor for TPN-associated epithelial barrier dysfunction, and both TNFR1 and TNFR2 are involved in EBF loss. Nuclear factor-B and MLCK signalling appear to be important downstream mediators involved in this TNF-α signalling process.

Intestinal microbial diversity and perioperative complications

BACKGROUND AND AIMS

Enteral nutrient deprivation via parenteral nutrition (PN) in a mouse model leads to a local mucosal inflammatory response. This proinflammatory response leads to a loss of epithelial barrier function and atrophy of the intestine. Although the underlying mechanisms are unknown, a potential contributing factor is the impact PN has on the intestinal microbiome. We recently identified a shift in the intestinal microbial community in mice given PN; however, it is unknown whether such changes occur in humans. We hypothesized that similar microbial changes occur in humans during periods of enteral nutrient deprivation.

METHODS

A series of small bowel specimens were obtained from pediatric and adult patients undergoing small intestinal resection. Mucosally associated bacteria were harvested and analyzed using 454 pyrosequencing techniques. Statistical analysis of microbial diversity and differences in microbial characteristics were assessed between enterally fed and enterally deprived portions of the intestine. Occurrence of postoperative infectious and anastomotic complications was also examined.

RESULTS

Pyrosequencing demonstrated a wide variability in microbial diversity within all groups. Principal coordinate analysis demonstrated only a partial stratification of microbial communities between fed and enterally deprived groups. Interestingly, a tight correlation was identified in patients who had a low level of enteric microbial diversity and those who developed postoperative enteric-derived infections or intestinal anastomotic disruption.

CONCLUSIONS

Loss of enteral nutrients and systemic antibiotic therapy in humans is associated with a significant loss of microbial biodiversity within the small bowel mucosa. These changes were associated with a number of enteric-derived intestinal infections and intestinal anastomotic disruptions.

Effect of hyperoxia on pulmonary SIgA and its components, IgA and SC

Purpose

Oxygen therapy (hyperoxia) is essential for the treatment of some neonatal critical care conditions. The lung is the primary target for the changes induced by hyperoxia. Secretory immunoglobulin A (SIgA), IgA and secretory component (SC) reflect the local immunity in the respiratory tract induced by hyperoxia.

Methods

The enzyme-linked immunosorbent assay, immunohistochemistry staining, Western blot and Real-time PCR were used to detect the levels of cytokines, IgA and SIgA in bronchoalveolar lavage as well as IgA and SC/pIgR in pulmonary tissue.

Results

The levels of IgA and SIgA in BAL fluid were gradually increased following neonatal rat development. Compared with air-inhaling group, in the hyperoxia group IgA, SIgA and other cytokines except IL-1 in BAL fluid were significantly elevated on the 3rd, 5th and 7th days, but on the 10th day TNF-α, SIgA and IgA rapidly decreased. In the hyperoxia group, both the protein expression of SC/pIgR and the mRNA expression of SC/pIgR were remarkably increased on the 3rd, 5th and 7th days, but were significantly decreased on the 10th day, respectively. Conclusion: The large amount of SIgA, IgA and SC in the early period of hyperoxia might protect the lungs of the neonatal rats against acute pulmonary injury, however, in the late period of hyperoxia, the abruptly drop of SIgA and its component might lead to pulmonary immunity abnormality. In hyperoxia, the increased expression of cytokines might contribute to the expression of IgA and SC.