Intestinal crosstalk: a new paradigm for understanding the gut as the "motor" of critical illness

Gut failure in critical care: old school versus new school

The concept of bacterial translocation and gut-origin sepsis as causes of systemic infectious complications and multiple organ deficiency syndrome in surgical and critically ill patients has been a recurring issue over the last decades attracting the scientific interest. Although gastrointestinal dysfunction seemingly arises frequently in intensive care unit patients, it is usually underdiagnosed or underestimated, because the pathophysiology involved is incompletely understood and its exact clinical relevance still remains controversial with an unknown yet probably adverse impact on the patients' outcome. The purpose of this review is to define gut-origin sepsis and related terms, to describe the mechanisms leading to gut-derived complications, and to illustrate the therapeutic options to prevent or limit these untoward processes.

The contribution of mast cells to postoperative ileus in experimental and clinical studies

The persistent phase of postoperative ileus (POI) is mediated by inflammatory activation of the resident myeloid immune cell population in the gut wall, likely elicited by neurogenic activation. Mast cells are thought to play a critical role in this inflammatory response and involvement of mast cells in POI has been investigated and described thoroughly in experimental studies. Intestinal manipulation (IM) leads to degranulation of mast cells, resulting in an increase in mast cell proteases in peritoneal fluid and gut tissue. The inflammatory infiltrate formed in the intestinal wall thereby impairs gastrointestinal motility. In the clinical study by Berdun et al., the experimentally known association between mast cell degranulation and delayed motility is shown in a clinical setting. These findings are important and open up therapeutic opportunities to reduce or prevent POI. In this mini-review, the role of mast cells in POI is discussed. Furthermore, an update is given on the involvement of the inflammatory response in POI and potential therapeutic strategies.

The preventive effects of dexmedetomidine against intestinal ischemia-reperfusion injury in Wistar rats

OBJECTIVES

Intestinal ischemia-reperfusion is a major problem, which may lead to multiorgan failure and death. The aim of this study was to evaluate the protective effects of dexmedetomidine on cell proliferation, antioxidant system, cell death, and structural integrity in intestinal injury induced by ischemia-reperfusion in rats.

MATERIALS AND METHODS

Animals were randomized into three groups: group A, sham-operated or control; group B, intestinal ischemia/reperfusion (IR); and group C, intestinal IR pretreated with 50 μg of dexmedetomidine. Intestine tissue was collected from all rats 30 min after desufflation, and fresh frozen for histological and biochemical evaluation.

RESULTS

The intestinal tissue of group B rats showed a significant decrease in the antioxidant enzyme activities. However, these enzyme activities were improved by the administration of dexmedetomidine. Inhibiting the protein expression of MCP7, PAR2, P-JAK, P-STAT1, and P-STAT3 proved the protective effect of dexmedetomidine. The immunohistochemical staining revealed its protective effect by maintaining the normal structural integrity, less caspase-3 immuno reactivity, and increased cell proliferation count in the intestinal tissues.

CONCLUSIONS

Intraperitoneal injection of dexmedetomidine significantly protected intestine IR injury in rats by inhibiting the inflammatory response, intestinal epithelial apoptosis, and maintaining structural integrity of intestinal cells.

Unfractionated heparin attenuates intestinal injury in mouse model of sepsis by inhibiting heparanase

Intestinal injury is a key feature in sepsis. Heparanase, a heparin sulfate-specific glucuronidase, mediates the onset of organ injury during early sepsis. Heparin has the function to attenuate inflammation and injury induced by multiple factors; however, whether unfractionated heparin (UFH) can attenuate the intestinal injury induced by sepsis as well as the underlying mechanism is still unknown. In the present study, the function of UFH in intestinal injury induced by sepsis was explored. Results of our study showed that after CLP operation, the inflammatory response and expression of heparanase were increased and NF-κB and MAPK P38 signaling pathways were activated. However, pretreatment with UFH will inhibit the expression and activation of heparanase, and reverse the activation of NF-κB and MAPK P38 signaling pathways, thus attenuating inflammatory responses induced by sepsis. These results suggest that UFH may be a promising therapeutic drug for intestinal injury caused by sepsis.

Impacts of gut bacteria on human health and diseases

Gut bacteria are an important component of the microbiota ecosystem in the human gut, which is colonized by 10¹⁴ microbes, ten times more than the human cells. Gut bacteria play an important role in human health, such as supplying essential nutrients, synthesizing vitamin K, aiding in the digestion of cellulose, and promoting angiogenesis and enteric nerve function. However, they can also be potentially harmful due to the change of their composition when the gut ecosystem undergoes abnormal changes in the light of the use of antibiotics, illness, stress, aging, bad dietary habits, and lifestyle. Dysbiosis of the gut bacteria communities can cause many chronic diseases, such as inflammatory bowel disease, obesity, cancer, and autism. This review summarizes and discusses the roles and potential mechanisms of gut bacteria in human health and diseases.

Protective effect of pioglitazone on sepsis-induced intestinal injury in a rodent model

BACKGROUND

Pathogenesis and treatment of inflammatory gut barrier failure is an important problem in critical care. In this study, we examined the role of pioglitazone, an agonist of peroxisome proliferator-activated receptor gamma, in gut barrier failure during experimental peritonitis in rats.

MATERIALS AND METHODS

Male rats were randomly divided into three groups as follows: sham, sepsis, and sepsis + pioglitazone. Sepsis was achieved by means of the cecal ligation and puncture (CLP). Pioglitazone was administered intraperitoneally (10 mg/kg/d) for 7 d before the experiment. Animals were killed at 24 h or followed 72 h for survival. The tissue level of tumor necrosis factor-α, interleukin-6, superoxide dismutase, malondialdehyde, and myeloperoxidase was measured. Intestinal mucosa injury was assessed histologically. The plasma fluorescein isothiocyanate-dextran, D-lactic acid, and intestinal diamine oxidase were determined to evaluate the permeability and integrity of intestinal mucosal epithelium. Vena cava blood and tissue samples were used to monitor bacterial translocation.

RESULTS

Intestinal inflammation, oxidize stress, neutrophil infiltration, morphology injury, and impaired permeability of the small intestine in the CLP group were found more severe than those in the sham group. Application of pioglitazone not only minimized all the indicators of intestinal injury and barrier failure but also improved the survival of septic rats induced by CLP.

CONCLUSIONS

Our novel findings suggest that pioglitazone could protect against intestinal injury and maintain intestinal barrier integrity and might be a useful strategy to ameliorate intestinal failure in polymicrobial sepsis.

New insights into gastrointestinal anthrax infection

Bacterial infections are the primary cause of gastrointestinal (GI) disorders in both developing and developed countries, and are particularly dangerous for infants and children. Bacillus anthracis is the 'archetype zoonotic' pathogen; no other infectious disease affects such a broad range of species, including humans. Importantly, there are more case reports of GI anthrax infection in children than inhalational disease. Early diagnosis is difficult and widespread systemic disease develops rapidly. This review highlights new findings concerning the roles of the gut epithelia, commensal microbiota, and innate lymphoid cells (ILCs) in initiation of disease and systemic dissemination in animal models of GI anthrax, the understanding of which is crucial to designing alternative therapies that target the establishment of infection.

An infectious murine model for studying the systemic effects of opioids on early HIV pathogenesis in the gut

Opioids are known to exacerbate HIV pathogenesis, however current studies have been limited by models of HIV infection. Given that HIV causes many systemic effects via direct infection of host cells as well as indirect bystander effects, it is important to establish a systemic infection model in a small animal so that genetic tools can be utilized to elucidate the mechanisms of action. In this study, the systemic effects of EcoHIV infection, a modified HIV which can infect mouse cells, are examined in conjunction with morphine. EcoHIV infection with opioid treatment induced bacterial translocation from the lumen of the gut into systemic compartments such as liver, which is similar to observations in human patients with LPS. Bacterial translocation corresponds with alterations in gut morphology, disorganization of the tight junction protein occludin, and a concurrent increase in systemic inflammation in both IL-6 and TNFα. Long term infection also had increased expression of inflammatory cytokines in the CNS when co-treated with morphine. Overall, this study shows that EcoHIV is an appropriate model to study the effects of opioids on HIV pathogenesis, including the HIV-induced pathology at early stages of pathogenesis in the gut.

Gut microbiota and environment in patients with major burns – a preliminary report

INTRODUCTION

The gut is an important target organ after severe insult. Gut microbiota have an important role in immune response. However, the gut microbiota and environment have not been clarified in patients with burns. Therefore, we serially evaluated the gut microbiota and environment in patients with major burns.

METHODS

Fecal samples from five patients with major burns were measured for quantitative evaluation of the gut microbiota.

RESULTS

In the four survivors of major burns, the numbers of beneficial bacteria, especially those of total obligate anaerobes and Bifidobacterium, initially decreased, but then increased as the condition of the survivors improved. By contrast, the numbers severely decreased in the non-survivor as gut failure and sepsis progressed. The number of pathogenic bacteria such as Pseudomonas and Candida did not continue to increase in the survivors, whereas in the non-survivor the number increased and continued to higher counts. Short-chain fatty acids such as propionic and butyric acids decreased to lower-than-normal levels but tended to increase after recovery in the survivors. The levels remained below normal in the non-survivor.

CONCLUSIONS

The gut microbiota and environment are severely altered in patients with major burns. Consequently, abnormal gut conditions may have an influence on the systemic inflammatory response and multiple organ dysfunction syndrome. A novel treatment to maintain the gut microbiota and environment is expected in the future.

Amelioration of hypoxia and LPS-induced intestinal epithelial barrier dysfunction by emodin through the suppression of the NF-κB and HIF-1α signaling pathways

Intestinal barrier dysfunction occurs in critical illnesses and involves the inflammatory and hypoxic injury of intestinal epithelial cells. Researchers are still defining the underlying mechanisms and evaluating therapeutic strategies for restoring intestinal barrier function. The anti-inflammatory drug, emodin, has been shown to exert a protective effect on intestinal barrier function; however, its mechanisms of action remain unknown. In this study, we investigated the protective effects of emodin on intestinal barrier function and the underlying mechanisms in intestinal epithelial cells challenged with lipopolysaccharide (LPS) and hypoxia/reoxygenation (HR). To induce barrier dysfunction, Caco-2 monolayers were subjected to HR with or without LPS treatment. Transepithelial electrical resistance and paracellular permeability were measured to evaluate barrier function. The expression of the tight junction (TJ) proteins, zonula occludens (ZO)-1, occludin, and claudin-1, as well as that of hypoxia-inducible factor (HIF)-1α, phosphor-IκB-α, phosphor-nuclear factor (NF)-κB p65 and cyclooxygenase (COX)-2 was determined by western blot analysis. The results revealed that emodin markedly attenuated the decrease in transepithelial electrical resistance and the increase in paracellular permeability in the Caco-2 monolayers treated with LPS and subjected to HR. Emodin also markedly alleviated the damage caused by LPS and HR (manifested by a decrease in the expression of the TJ protein, ZO-1), and inhibited the expression of HIF-1α, IκB-α, NF-κB and COX-2 in a dose-dependent manner. In conclusion, our data suggest that emodin attenuates LPS- and HR-induced intestinal epithelial barrier dysfunction by inhibiting the HIF-1α and NF-κB signaling pathways and preventing the damage caused to the TJ barrier (shown by the decrease in the expression of ZO-1).

Effect of acute, slightly increased intra-abdominal pressure on intestinal permeability and oxidative stress in a rat model

INTRODUCTION

Intra-abdominal hypertension (IAH) is known as a common, serious complication in critically ill patients. Bacterial translocation and permeability changes are considered the pathophysiological bases for IAH-induced enterogenic endotoxemia and subsequent multiorgan failure. Nevertheless, the effects of slightly elevated intra-abdominal pressures (IAPs) on the intestinal mucosa and the associated mechanisms remain unclear.

METHODS

To investigate the acute effects of different nitrogen pneumoperitoneum grades on colonic mucosa, male Sprague-Dawley rats were assigned to six groups with different IAPs (0 [control], 4, 8, 12, 16, and 20 mmHg, n = 6/group). During 90 min of exposure, we dynamically monitored the heart rate and noninvasive hemodynamic parameters. After gradual decompression, arterial blood gas analyses were conducted. Thereafter, structural injuries to the colonic mucosa were identified using light microscopy. Colon permeability was determined using the expression of tight junction proteins, combined with fluorescein isothiocyanate dextran (FD-4) absorption. The pro-oxidant-antioxidant balance was determined based on the levels of malondialdehyde (MDA) and antioxidant enzymes.

RESULTS

IAH significantly affected the histological scores of the colonic mucosa, tight junction protein expression, mucosal permeability, and pro-oxidant-antioxidant balance. Interestingly, elevations of IAP that were lower than the threshold for IAH also showed a similar, undesirable effect. In the 8 mmHg group, mild hyponatremia, hypocalcemia, and hypoxemia occurred, accompanied by reduced blood and abdominal perfusion pressures. Mild microscopic inflammatory infiltration and increased MDA levels were also detected. Moreover, an 8-mm Hg IAP markedly inhibited the expression of tight junction proteins, although no significant differences in FD-4 permeability were observed between the 0- and 8-mmHg groups.

CONCLUSIONS

Acute exposure to slightly elevated IAP may result in adverse effects on intestinal permeability and the pro-oxidant-antioxidant balance. Therefore, in patients with critical illnesses, IAP should be dynamically monitored and corrected, as soon as possible, to prevent intestinal mucosal injury and subsequent gut-derived sepsis.

Serum diamine oxidase as a hemorrhagic shock biomarker in a rabbit model

Background

In prolonged hemorrhagic shock, reductions in intestinal mucosal blood perfusion lead to mucosal barrier damage and systemic inflammation. Gastrointestinal failure in critically ill patients has a poor prognosis, so early assessment of mucosal barrier injury in shock patients is clinically relevant. Unfortunately, there is no serum marker that can accurately assess intestinal ischemia-reperfusion injury.

Objective

The aim of this study was to assess if serum diamine oxidase levels can reflect intestinal mucosal injury subsequent to prolonged hemorrhagic shock.

Methods

Thirty New Zealand white rabbits were divided into three groups: a control group, a medium blood pressure (BP) group (exsanguinated to a shock BP of 50 to 41 mm Hg), and a low BP group (exsanguinated to a shock blood pressure of 40 to 31 mm Hg), in which the shock BP was sustained for 180 min prior to fluid resuscitation.

Results

The severity of hemorrhagic shock in the low BP group was significantly greater than that of the medium BP group according to the post-resuscitation BP, serum tumor necrosis factor (TNF)-α, and arterial lactate. Intestinal damage was significantly more severe in the low BP group according to Chiu’s scoring, claudin-1, intercellular adhesion molecule (ICAM)-1, and myeloperoxidase expression. Serum diamine oxidase was significantly increased in the low BP group compared to the medium BP and control groups and was negatively correlated with shock BP.

Conclusion

Serum diamine oxidase can be used as a serological marker in evaluating intestinal injury and shows promise as an indicator of hemorrhagic shock severity.

Intestine-specific deletion of microsomal triglyceride transfer protein increases mortality in aged mice

Background

Mice with conditional, intestine-specific deletion of microsomal triglyceride transfer protein (Mttp-IKO) exhibit a complete block in chylomicron assembly together with lipid malabsorption. Young (8–10 week) Mttp-IKO mice have improved survival when subjected to a murine model of Pseudomonas aeruginosa-induced sepsis. However, 80% of deaths in sepsis occur in patients over age 65. The purpose of this study was to determine whether age impacts outcome in Mttp-IKO mice subjected to sepsis.

Methods

Aged (20–24 months) Mttp-IKO mice and WT mice underwent intratracheal injection with P. aeruginosa. Mice were either sacrificed 24 hours post-operatively for mechanistic studies or followed seven days for survival.

Results

In contrast to young septic Mttp-IKO mice, aged septic Mttp-IKO mice had a significantly higher mortality than aged septic WT mice (80% vs. 39%, p = 0.005). Aged septic Mttp-IKO mice exhibited increased gut epithelial apoptosis, increased jejunal Bax/Bcl-2 and Bax/Bcl-X_L ratios yet simultaneously demonstrated increased crypt proliferation and villus length. Aged septic Mttp-IKO mice also manifested increased pulmonary myeloperoxidase levels, suggesting increased neutrophil infiltration, as well as decreased systemic TNFα compared to aged septic WT mice.

Conclusions

Blocking intestinal chylomicron secretion alters mortality following sepsis in an age-dependent manner. Increases in gut apoptosis and pulmonary neutrophil infiltration, and decreased systemic TNFα represent potential mechanisms for why intestine-specific Mttp deletion is beneficial in young septic mice but harmful in aged mice as each of these parameters are altered differently in young and aged septic WT and Mttp-IKO mice.

CO and CO-releasing molecules (CO-RMs) in acute gastrointestinal inflammation

Carbon monoxide (CO) is enzymatically generated in mammalian cells alongside the liberation of iron and the production of biliverdin and bilirubin. This occurs during the degradation of haem by haem oxygenase (HO) enzymes, a class of ubiquitous proteins consisting of constitutive and inducible isoforms. The constitutive HO2 is present in the gastrointestinal tract in neurons and interstitial cells of Cajal and CO released from these cells might contribute to intestinal inhibitory neurotransmission and/or to the control of intestinal smooth muscle cell membrane potential. On the other hand, increased expression of the inducible HO1 is now recognized as a beneficial response to oxidative stress and inflammation. Among the products of haem metabolism, CO appears to contribute primarily to the antioxidant and anti-inflammatory effects of the HO1 pathway explaining the studies conducted to exploit CO as a possible therapeutic agent. This article reviews the effects and, as far as known today, the mechanism(s) of action of CO administered either as CO gas or via CO-releasing molecules in acute gastrointestinal inflammation. We provide here a comprehensive overview on the effect of CO in experimental in vivo models of post-operative ileus, intestinal injury during sepsis and necrotizing enterocolitis. In addition, we will analyse the in vitro data obtained so far on the effect of CO on intestinal epithelial cell lines exposed to cytokines, considering the important role of the intestinal mucosa in the pathology of gastrointestinal inflammation.

Rapid and Sustained Long-Term Decrease of Fecal Short-Chain Fatty Acids in Critically Ill Patients With Systemic Inflammatory Response Syndrome

BACKGROUND

The gut is an important target organ for injury after severe insult. Short-chain fatty acids (SCFAs) are end-products of fermentation of dietary fibers by anaerobic microbiota. They are related to intestinal energy, motility, and transport and to protective effects against infection and inflammation. However, there are few clinical data on SCFAs in critically ill patients. We evaluated serial change in fecal SCFAs in patients with severe systemic inflammatory response syndrome (SIRS).

PATIENTS AND METHODS

This study included 140 intensive care unit (ICU) patients who fulfilled the criteria of SIRS and had a serum C-reactive protein level of >10 mg/dL. A fecal sample was used for quantitative measurement of fecal SCFA (butyrate, propionate, and acetate) concentrations by high-performance liquid chromatography. Fecal SCFAs were evaluated weekly for 6 weeks after admission. Data obtained from patients were compared with corresponding data from healthy volunteers.

RESULTS

SIRS resulted from infection in 78 patients, trauma in 30, burns in 12, and other causes in 20. Fecal concentrations of butyrate, propionate, and acetate in these patients decreased significantly compared with those in healthy volunteers and remained low throughout the 6 weeks of the patients' ICU stay. Fecal concentrations of SCFAs in the patients with gastrointestinal complications, including enteritis and dysmotility, were lower than those in the patients without gastrointestinal complications.

CONCLUSIONS

Concentrations of fecal SCFAs in patients with severe SIRS were significantly lower than those in healthy volunteers over a 6-week period. Maintenance of SCFAs may have therapeutic potential to prevent gastrointestinal complications in critically ill patients.

Is intra-abdominal hypertension a missing factor that drives multiple organ dysfunction syndrome?

In a recent issue of Critical Care, Cheng and colleagues conducted a rabbit model study that demonstrated that intra-abdominal hypertension (IAH) may damage both gut anatomy and function. With only 6 hours of IAH at 25 mmHg, these authors observed an 80% reduction in mucosal blood flow, an exponential increase in mucosal permeability, and erosion and necrosis of the jejunal villi. Such dramatic findings should remind all caring for the critically ill that IAH may severely damage the normal gut barrier functions and thus may be reasonably expected to facilitate bacterial and mediator translocation. The potential contribution of IAH as a confounding factor in the efficacy of selective decontamination of the digestive tract should be considered.

Somatostatin inhibits the production of interferon-γ by intestinal epithelial cells during intestinal ischemia-reperfusion in macaques

BACKGROUND

Our previous study found that somatostatin (SST) inhibited the intestinal inflammatory injury in a macaque model of intestinal ischemia-reperfusion (IIR); however, the underlying mechanism was unclear.

AIMS

The present study was aimed to investigate the effects of SST on IFN-γ and the systemic inflammatory response after IIR.

METHODS

Fifteen macaques were randomly divided into controls, IIR and SST+ IIR groups. ELISA was performed to measure IFN-γ in ileum tissues, ileac epithelial cells (IECs) and ileal lymphocytes, as well as the systemic levels of IL-6, IL-1β, TNF-α and IFN-γ in the peripheral circulation and the portal vein. HE staining was performed to evaluate morphological changes in vital organs. Immunohistochemistry was performed to identify the distribution of IFN-γ, CD4, CD8 and CD57 in the ileum.

RESULTS

After IIR, IFN-γ level was significantly increased in the IECs. IL-6, IL-1β and TNF-α were significantly increased in both the portal vein and the peripheral circulation; in contrast, IFN-γ level was increased in the portal vein alone. Prophylactic SST reversed the change in IFN-γ in the IECs and portal vein. SST led to an alleviation of the pathological changes in systemic vital organs. The distribution of CD4(+), CD57(+) and CD8(+) cells was not positively correlated with the secretion of IFN-γ.

CONCLUSION

IECs are the main source of IFN-γ production after IIR. SST may indirectly lead to mast cell deactivation through the inhibition of IFN-γ production by IECs. Pretreatment with SST may be beneficial for preventing a massive systemic inflammatory response in vital organs after IIR.

The role of intestinal mucosa injury induced by intra-abdominal hypertension in the development of abdominal compartment syndrome and multiple organ dysfunction syndrome

Introduction

Abdominal distension is common in critical illness. There is a growing recognition that intra-abdominal hypertension (IAH) may complicate nonsurgical critical illness as well as after abdominal surgery. However, the pathophysiological basis of the injury to the intestinal mucosal barrier and its influence on the onset of abdominal compartment syndrome (ACS) and multiorgan dysfunction syndrome (MODS) remain unclear. We measured intestinal microcirculatory blood flow (MBF) during periods of raised intra-abdominal pressure (IAP) and examined how this influenced intestinal permeability, systemic endotoxin release, and histopathological changes.

Methods

To test different grades of IAH to the injury of intestinal mucosa, 96 New Zealand white rabbits aged 5 to 6 months were exposed to increased IAP under nitrogen pneumoperitoneum of 15 mmHg or 25 mmHg for 2, 4 or 6 hours. MBF was measured using a laser Doppler probe placed against the jejunal mucosa through a small laparotomy. Fluorescein isothiocyanate (FITC)-conjugated dextran was administered by gavage. Intestinal injury and permeability were measured using assays for serum FITC-dextran and endotoxin, respectively, after each increase in IAP. Structural injury to the intestinal mucosa at different levels of IAH was confirmed by light and transmission electron microscopy.

Results

MBF reduced from baseline by 40% when IAP was 15 mmHg for 2 hours. This doubled to 81% when IAP was 25 mmHg for 6 hours. Each indicator of intestinal injury increased significantly, proportionately with IAP elevation and exposure time. Baseline serum FITC-dextran was 9.30 (± SD 6.00) μg/ml, rising to 46.89 (±13.43) μg/ml after 15 mmHg IAP for 4 hours (P <0.01), and 284.59 (± 45.18) μg/ml after 25 mmHg IAP for 6 hours (P <0.01). Endotoxin levels showed the same pattern. After prolonged exposure to increased IAP, microscopy showed erosion and necrosis of jejunal villi, mitochondria swelling and discontinuous intracellular tight junctions.

Conclusions

Intra-abdominal hypertension can significantly reduce MBF in the intestinal mucosa, increase intestinal permeability, result in endotoxemia, and lead to irreversible damage to the mitochondria and necrosis of the gut mucosa. The dysfunction of the intestinal mucosal barrier may be one of the important initial factors responsible for the onset of ACS and MODS.

Overexpressed miRNA-155 dysregulates intestinal epithelial apical junctional complex in severe acute pancreatitis

AIM: To investigate whether miRNA-155 (miR-155) dysregulates apical junctional complex (AJC) protein expression in experimental severe acute pancreatitis (SAP).

METHODS: Twenty-four male BALB/c mice were randomly assigned to two groups: the SAP group (n = 12) receiving sequential intraperitoneal injection of 50 µg/kg caerulein and 10 mg/kg lipopolysaccharide over 6 h, and the control group (n = 12) receiving intraperitoneal injection of normal saline. Animals were sacrificed 3 h following the last injection for collection of blood samples and pancreas and distal ileal segment specimens. Routine pancreas and intestine histology was used to assess SAP pathology and intestinal epithelial barrier damage. Levels of serum amylase, diamine oxidase (DAO), and tumor necrosis factor (TNF)-α were determined using commercial kits. Total RNA samples were isolated from intestinal epithelial specimens and reversely transcribed into cDNA. miR-155 and RhoA mRNA expression profiles were determined using quantitative real-time polymerase chain reaction. Target genes for miR-155 were predicted using the miRTarBase database, RNA22 and PicTar computational methods. Western blotting was performed to quantitate the protein expression levels of the target gene RhoA, as well as zonula occludens (ZO)-1 and E-cadherin, two AJC component proteins.

RESULTS: Intraperitoneal injection of caerulein and lipopolysaccharide successfully induced experimental acute pancreatic damage (SAP vs control, 10.0 ± 2.0 vs 3.2 ± 1.2, P < 0.01) and intestinal epithelial barrier damage (3.2 ± 0.7 vs 1.4 ± 0.7, P < 0.01). Levels of serum amylase (21.6 ± 5.1 U/mL vs 14.3 ± 4.2 U/mL, P < 0.01), DAO (21.4 ± 4.1 mg/mL vs 2.6 ± 0.8 mg/mL, P < 0.01), and TNF-α (61.0 ± 15.1 ng/mL vs 42.9 ± 13.9 ng/mL, P < 0.01) increased significantly in SAP mice compared to those in control mice. miR-155 was significantly overexpressed in SAP intestinal epithelia (1.94 ± 0.50 fold vs 1.03 ± 0.23 fold, P < 0.01), and RhoA gene containing three miR-155-specific binding sites in the three prime untranslated regions was one of the target genes for miR-155. RhoA (22.7 ± 5.8 folds vs 59.6 ± 11.6 folds, P < 0.01), ZO-1 (46 ± 18 folds vs 68 ± 19 folds, P < 0.01), and E-cadherin proteins (48 ± 15 folds vs 77 ± 18 folds, P < 0.01) were underexpressed in SAP intestinal epithelia although RhoA mRNA expression was not significantly changed in SAP (0.97 ± 0.18 folds vs 1.01 ± 0.17 folds, P > 0.05).

CONCLUSION: TNF-α-regulated miR-155 overexpression inhibits AJC component protein syntheses of ZO-1, and E-cadherin by downregulating post-transcriptional RhoA expression, and disrupts intestinal epithelial barrier in experimental SAP.

Inhibition of IKKβ in enterocytes exacerbates sepsis-induced intestinal injury and worsens mortality

OBJECTIVES

Nuclear factor-κB is a critical regulator of cell-survival genes and the host inflammatory response. The purpose of this study was to investigate the role of enterocyte-specific NF-kB in sepsis through selective ablation of IkB kinase.

DESIGN

Prospective, randomized controlled study.

SETTING

Animal laboratories in university medical centers.

SUBJECTS AND INTERVENTIONS

Mice lacking functional NF-kB in their intestinal epithelium (Vil-Cre/Ikkβ) and wild-type mice were subjected to sham laparotomy or cecal ligation and puncture. Animals were killed at 24 hours or followed 7 days for survival.

MEASUREMENTS AND MAIN RESULTS

Septic wild-type mice had decreased villus length compared with sham mice, whereas villus atrophy was further exacerbated in septic Vil-Cre/Ikkβ mice. Sepsis induced an increase in intestinal epithelial apoptosis compared with sham mice, which was further exacerbated in Vil-Cre/Ikkβ mice. Sepsis induced intestinal hyperpermeability in wild-type mice compared with sham mice, which was further exacerbated in septic Vil-Cre/Ikkβ mice. This was associated with increased intestinal expression of claudin-2 in septic wild-type mice, which was further increased in septic Vil-Cre/Ikkβ mice. Both, pro-inflammatory and anti-inflammatory cytokines were increased in serum following cecal ligation and puncture, and interleukin 10 and monocyte chemoattractant protein-1 levels were higher in septic Vil-Cre/Ikkβ mice than in septic wild-type mice. All septic mice were bacteremic, but no differences in bacterial load were identified between wild-type and Vil-Cre/Ikkβ mice. To determine the functional significance of these results, animals were followed for survival. Septic wild-type mice had lower mortality than septic Vil-Cre/Ikkβ mice (47% vs 80%, p<0.05). Antitumor necrosis factor administration decreased intestinal apoptosis, permeability, and mortality in wild-type septic mice, and a similar improvement in intestinal integrity and survival were seen when antitumor necrosis factor was given to Vil-Cre/Ikkβ mice.

CONCLUSIONS

Enterocyte-specific NF-kB has a beneficial role in sepsis by partially preventing sepsis-induced increases in apoptosis and permeability, which are associated with worsening mortality.

Character and temporal evolution of apoptosis in acetaminophen-induced acute liver failure*

OBJECTIVE

To evaluate the role of hepatocellular and extrahepatic apoptosis during the evolution of acetaminophen-induced acute liver failure.

DESIGN AND SETTING

A prospective observational study in two tertiary liver transplant units.

PATIENTS

Eighty-eight patients with acetaminophen-induced acute liver failure were recruited. Control groups included patients with nonacetaminophen-induced acute liver failure (n = 13), nonhepatic multiple organ failure (n = 28), chronic liver disease (n = 19), and healthy controls (n = 11).

MEASUREMENTS

Total and caspase-cleaved cytokeratin-18 (M65 and M30) measured at admission and sequentially on days 3, 7, and 10 following admission. Levels were also determined from hepatic vein, portal vein, and systemic arterial blood in seven patients undergoing transplantation. Protein arrays of liver homogenates from patients with acetaminophen-induced acute liver failure were assessed for apoptosis-associated proteins, and histological assessment of liver tissue was performed.

MAIN RESULTS

Admission M30 levels were significantly elevated in acetaminophen-induced acute liver failure and non-acetaminophen induced acute liver failure patients compared with multiple organ failure, chronic liver disease, and healthy controls. Admission M30 levels correlated with outcome with area under receiver operating characteristic of 0.755 (0.639-0.885, p < 0.001). Peak levels in patients with acute liver failure were seen at admission then fell significantly but did not normalize over 10 days. A negative gradient of M30 from the portal to hepatic vein was demonstrated in patients with acetaminophen-induced acute liver failure (p = 0.042) at the time of liver transplant. Analysis of protein array data demonstrated lower apoptosis-associated protein and higher catalase concentrations in acetaminophen-induced acute liver failure compared with controls (p < 0.05). Explant histological analysis revealed evidence of cellular proliferation with an absence of histological evidence of apoptosis.

CONCLUSIONS

Hepatocellular apoptosis occurs in the early phases of human acetaminophen-induced acute liver failure, peaking on day 1 of hospital admission, and correlates strongly with poor outcome. Hepatic regenerative/tissue repair responses prevail during the later stages of acute liver failure where elevated levels of M30 are likely to reflect epithelial cell death in extrahepatic organs.

Inhibition of intestinal epithelial apoptosis improves survival in a murine model of radiation combined injury

World conditions place large populations at risk from ionizing radiation (IR) from detonation of dirty bombs or nuclear devices. In a subgroup of patients, ionizing radiation exposure would be followed by a secondary infection. The effects of radiation combined injury are potentially more lethal than either insult in isolation. The purpose of this study was to determine mechanisms of mortality and possible therapeutic targets in radiation combined injury. Mice were exposed to IR with 2.5 Gray (Gy) followed four days later by intratracheal methicillin-resistant Staphylococcus aureus (MRSA). While either IR or MRSA alone yielded 100% survival, animals with radiation combined injury had 53% survival (p = 0.01). Compared to IR or MRSA alone, mice with radiation combined injury had increased gut apoptosis, local and systemic bacterial burden, decreased splenic CD4 T cells, CD8 T cells, B cells, NK cells, and dendritic cells, and increased BAL and systemic IL-6 and G-CSF. In contrast, radiation combined injury did not alter lymphocyte apoptosis, pulmonary injury, or intestinal proliferation compared to IR or MRSA alone. In light of the synergistic increase in gut apoptosis following radiation combined injury, transgenic mice that overexpress Bcl-2 in their intestine and wild type mice were subjected to IR followed by MRSA. Bcl-2 mice had decreased gut apoptosis and improved survival compared to WT mice (92% vs. 42%; p<0.01). These data demonstrate that radiation combined injury results in significantly higher mortality than could be predicted based upon either IR or MRSA infection alone, and that preventing gut apoptosis may be a potential therapeutic target.

Immunomodulation in sepsis: the role of endotoxin removal by polymyxin B-immobilized cartridge

Severe sepsis results in high morbidity and mortality. Immunomodulation strategies could be an adjunctive therapy to treat sepsis. Endotoxin is a component of gram-negative bacteria and plays an important role in the pathogenesis of septic shock when it is recognized by immune cells. Removal of endotoxin could be an effective adjunctive approach to the management of sepsis. Devices to adsorb endotoxin or inflammatory cytokines have been designed as a strategy to treat severe sepsis, especially sepsis caused by gram-negative bacteria. Polymyxin B-immobilized cartridge has been successfully used to treat patients with sepsis of abdominal origin. Although this cartridge was conceived to adsorb endotoxin, several other immunological mechanisms have been elucidated, and this device has also yielded promising results in patients with nonseptic respiratory failure. In this paper, we summarize the immune modulation actions of Polymyxin B-immobilized cartridge to explore its potential usefulness beyond endotoxin elimination.

Gastro-intestinal vascular emergencies

Gastro-Intestinal Vascular Emergencies include all digestive ischaemic injuries related to acute or chronic vascular and/or haemodynamic diseases. Gastro-intestinal ischaemic injuries can be occlusive or non-occlusive, arterial or venous, localized or generalized, superficial or transmural and share the risks of infarction, organ failure and death. The diagnosis must be suspected, at the initial presentation of any sudden, continuous and unusual abdominal pain, contrasting with normal physical examination. Risk factors are often unknown at presentation and no biomarker is currently available. The diagnosis is confirmed by abdominal computed tomography angiography identifying intestinal ischaemic injury, either with vascular occlusion or in a context of low flow. Recent knowledge in the pathophysiology of acute mesenteric ischaemia, clinical experience and existing recommendations have generated a multimodal and multidisciplinary management strategy. Based on the gastro-intestinal viability around a simple algorithm, and coordinated by gastroenterologists, the dual aim is to avoid large intestinal resections and death.

Redefining the gut as the motor of critical illness

The gut is hypothesized to play a central role in the progression of sepsis and multiple organ dysfunction syndrome. Critical illness alters gut integrity by increasing epithelial apoptosis and permeability and by decreasing epithelial proliferation and mucus integrity. Additionally, toxic gut-derived lymph induces distant organ injury. Although the endogenous microflora ordinarily exist in a symbiotic relationship with the gut epithelium, severe physiological insults alter this relationship, leading to induction of virulence factors in the microbiome, which, in turn, can perpetuate or worsen critical illness. This review highlights newly discovered ways in which the gut acts as the motor that perpetuates the systemic inflammatory response in critical illness.

Probiotic administration reduces mortality and improves intestinal epithelial homeostasis in experimental sepsis

BACKGROUND

Recent clinical trials indicate that probiotic administration in critical illness has potential to reduce nosocomial infections and improve clinical outcome. However, the mechanism(s) of probiotic-mediated protection against infection and sepsis remain elusive. The authors evaluated the effects of Lactobacillus rhamnosus GG (LGG) and Bifidobacterium longum (BL) on mortality, bacterial translocation, intestinal epithelial homeostasis, and inflammatory response in experimental model of septic peritonitis.

METHODS

Cecal ligation and puncture (n=14 per group) or sham laparotomy (n=8 per group) were performed on 3-week-old FVB/N weanling mice treated concomitantly with LGG, BL, or vehicle (orally gavaged). At 24 h, blood and colonic tissue were collected. In survival studies, mice were given probiotics every 24 h for 7 days (LGG, n=14; BL, n=10; or vehicle, n=13; shams, n=3 per group).

RESULTS

Probiotics significantly improved mortality after sepsis (92 vs. 57% mortality for LGG and 92 vs. 50% mortality for BL; P=0.003). Bacteremia was markedly reduced in septic mice treated with either probiotic compared with vehicle treatment (4.39±0.56 vs. 1.07±1.54; P=0.0001 for LGG; vs. 2.70±1.89; P=0.016 for BL; data are expressed as mean±SD). Sepsis in untreated mice increased colonic apoptosis and reduced colonic proliferation. Probiotics significantly reduced markers of colonic apoptosis and returned colonic proliferation to sham levels. Probiotics led to significant reductions in systemic and colonic inflammatory cytokine expression versus septic animals. Our data suggest that involvement of the protein kinase B pathway (via AKT) and down-regulation of Toll-like receptor 2/Toll-like receptor 4 via MyD88 in the colon may play mechanistic roles in the observed probiotic benefits.

CONCLUSIONS

Our data demonstrate that probiotic administration at initiation of sepsis can improve survival in pediatric experimental sepsis. The mechanism of this protection involves prevention of systemic bacteremia, perhaps via improved intestinal epithelial homeostasis, and attenuation of the local and systemic inflammatory responses.

Effects of exogenous vasoactive intestinal peptide on mesenteric lymph pathway during early intestinal ischemia-reperfusion injury in rats

Mesenteric lymph pathway serves as the primary route by which gut injury leads to systemic inflammation and distant organ injury. The inflammation of the intestinal tract is partially mediated by vasoactive intestinal peptide (VIP). Therefore, the aim of this study was to test whether exogenous VIP affects mesenteric lymph pathway during early intestinal ischemia-reperfusion (IIR) injury. Rats were randomized into control, control+VIP, IIR and IIR+VIP groups. The observation of mesenteric lymph flow was carried out by cannulation of mesenteric lymphatics. The distribution of in vivo lymphocyte trafficking was performed by (51)Cr labeled lymphocytes and was measured by γ-counter. Endotoxin concentration was assayed using the limulus test kit and TNF-α level was detected by ELISA. When IIR injury treated with VIP, the volumes of lymph flow increased by 80%, which caused the number of lymphocytes exiting in mesenteric lymphatic increased by 50% while the proportion of (51)Cr-lymphocytes in Peyer's patches, intestinal effector tissues, mesenteric nodes, large intestine, stomach decreased by 58%, 51%, 58%, 63%, 64% respectively at the 6th h after reperfusion following intestinal ischemia. Meanwhile, endotoxin and TNF-α levels in intestinal lymph decreased by 51% and 83%. These results suggest that exogenous VIP ameliorates IIR induced splanchnic organ damage via inhibition of toxic mediators reaching systemic circulation and reinforcement of the effective immune responses in gut-associated lymphoid tissues (GALT).

Significant changes in the intestinal environment after surgery in patients with colorectal cancer

BACKGROUND

There have been very few detailed reports of the intestinal environment after surgical treatment for colorectal cancer (CRC). We analysed faecal microbiota, organic acids and pH to investigate the influence of colorectal surgery on the intestinal environment.

METHODS

Faecal samples from 81 CRC patients were collected before the start of pre-operative preparation the day before surgery, as well as 7 days or more after surgery. Thirteen groups of intestinal microbiota, eight types of organic acids, and pH were measured using 16S rRNA-targeted reverse transcription-quantitative PCR, high-performance liquid chromatography and a pH meter, respectively.

RESULTS

Total bacterial counts (10.3 ± 0.6 vs. 9.4 ± 1.2 log10 cells/g; p < 0.001) and the numbers of 6 groups of obligate anaerobes were significantly decreased after surgery. In contrast, the populations of Enterobacteriaceae, Enterococcus, Staphylococcus and Pseudomonas were significantly increased. Post-operatively, the concentration of total organic acids was lower (77.9 ± 40.1 vs. 50.1 ± 37.0 μmol/g; p < 0.001) than the pre-operative concentration, and a significant reduction in short-chain fatty acids (SCFAs) was observed.

CONCLUSION

Significant changes in the intestinal environment, including marked decreases in obligate anaerobes, increases in pathogenic bacteria, and reductions in SCFAs, were detected after surgery for CRC.

Lipid-rich enteral nutrition regulates mucosal mast cell activation via the vagal anti-inflammatory reflex

Nutritional stimulation of the cholecystokinin-1 receptor (CCK-1R) and nicotinic acetylcholine receptor (nAChR)-mediated vagal reflex was shown to reduce inflammation and preserve intestinal integrity. Mast cells are important early effectors of the innate immune response; therefore modulation of mucosal mast cells is a potential therapeutic target to control the acute inflammatory response in the intestine. The present study investigates intestinal mast cell responsiveness upon nutritional activation of the vagal anti-inflammatory reflex during acute inflammation. Mucosal mast cell degranulation was induced in C57/Bl6 mice by administration of Salmonella enterica LPS. Lipid-rich enteral feeding prior to LPS significantly decreased circulatory levels of mouse mast cell protease at 30 min post-LPS compared with isocaloric low-lipid nutrition or fasting. CCK-1R blockage reversed the inhibitory effects of lipid-rich feeding, whereas stimulation of the peripheral CCK-1R mimicked nutritional mast cell inhibition. The effects of lipid-rich nutrition were negated by nAChR blockers chlorisondamine and α-bungarotoxin and vagal intestinal denervation. Accordingly, release of β-hexosaminidase by MC/9 mast cells following LPS or IgE-ovalbumin complexes was dose dependently inhibited by acetylcholine and nicotine. Application of GSK1345038A, a specific agonist of the nAChR α7, in bone marrow-derived mast cells from nAChR β2-/- and wild types indicated that cholinergic inhibition of mast cells is mediated by the nAChR α7 and is independent of the nAChR β2. Together, the present study reveals mucosal mast cells as a previously unknown target of the nutritional anti-inflammatory vagal reflex.

The vagal innervation of the gut and immune homeostasis

The central nervous system interacts dynamically with the immune system to modulate inflammation through humoral and neural pathways. Recently, in animal models of sepsis, the vagus nerve (VN) has been proposed to play a crucial role in the regulation of the immune response, also referred to as the cholinergic anti-inflammatory pathway. The VN, through release of acetylcholine, dampens immune cell activation by interacting with α-7 nicotinic acetylcholine receptors. Recent evidence suggests that the vagal innervation of the gastrointestinal tract also plays a major role controlling intestinal immune activation. Indeed, VN electrical stimulation potently reduces intestinal inflammation restoring intestinal homeostasis, whereas vagotomy has the reverse effect. In this review, we will discuss the current understanding concerning the mechanisms and effects involved in the cholinergic anti-inflammatory pathway in the gastrointestinal tract. Deeper investigation on this counter-regulatory neuroimmune mechanism will provide new insights in the cross-talk between the nervous and immune system leading to the identification of new therapeutic targets to treat intestinal immune disease.

Probiotics improve survival of septic rats by suppressing conditioned pathogens in ascites

AIM: To investigate the benefits of probiotics treatment in septic rats.

METHODS: The septic rats were induced by cecal ligation and puncture. The animals of control, septic model and probiotics treated groups were treated with vehicle and mixed probiotics, respectively. The mixture of probiotics included Bifidobacterium longum, Lactobacillus bulgaricus and Streptococcus thermophilus. We observed the survival of septic rats using different amounts of mixed probiotics. We also detected the bacterial population in ascites and blood of experimental sepsis using cultivation and real-time polymerase chain reaction. The severity of mucosal inflammation in colonic tissues was determined.

RESULTS: Probiotics treatment improved survival of the rats significantly and this effect was dose dependent. The survival rate was 30% for vehicle-treated septic model group. However, 1 and 1/4 doses of probiotics treatment increased survival rate significantly compared with septic model group (80% and 55% vs 30%, P < 0.05). The total viable counts of bacteria in ascites decreased significantly in probiotics treated group compared with septic model group (5.20 ± 0.57 vs 9.81 ± 0.67, P < 0.05). The total positive rate of hemoculture decreased significantly in probiotics treated group compared with septic model group (33.3% vs 100.0%, P < 0.05). The population of Escherichia coli and Staphylococcus aureus in ascites of probiotics treated group were decreased significantly compared with that of septic model group (3.93 ± 0.73 vs 8.80 ± 0.83, P < 0.05; 2.80 ± 1.04 vs 5.39 ± 1.21, P < 0.05). With probiotics treatment, there was a decrease in the scores of inflammatory cell infiltration into the intestinal mucosa in septic animals (1.50 ± 0.25 vs 2.88 ± 0.14, P < 0.01).

CONCLUSION: Escherichia coli and Staphylococcus aureus may be primary pathogens in septic rats. Probiotics improve survival of septic rats by suppressing these conditioned pathogens.

Factors influencing outcome in patients with cardiac arrest in the ICU

BACKGROUND

Post-arrest variables associated with long-term survival after cardiopulmonary resuscitation (CPR) in intensive care unit (ICU) patients remain unclear. This study was designed to identify pre- and intra-arrest factors associated with survival 3 months after CPR in ICU patients and to identify post-arrest factors associated with long-term survival in those who survived 24 h after CPR.

METHODS

A total of 131 ICU patients undergoing CPR from January 2009 to June 2010 were included. Data were retrospectively analysed and categorized based on the Utstein template.

RESULTS

The overall survival rate 3 months after CPR was 20.6%. Logistic regression analysis revealed that acute physiology and chronic health evaluation (APACHE) II score (odds ratio, 95% confidence interval, 0.87 [0.83-0.93]; P < 0.001), ventricular tachycardia/ventricular fibrillation (VT/VF, 5.55 [1.55-19.83]; P = 0.032), and normoxia during CPR (4.45 [1.34-14.71]; P = 0.045) were significant independent pre- and intra-arrest predictors of 3-month survival after CPR in ICU patients. Fifty-seven patients survived 24 h after CPR, and their 3-month survival rate was 47.4%. Early enteral nutrition (9.94 [1.96-50.43]; P = 0.030) and normoxia after return of spontaneous circulation (10.75 [2.03-55.56]; P = 0.030) were predictive of 3-month survival in patients who survived 24 h after CPR.

CONCLUSIONS

Normoxia during CPR and VT/VF were predictors of long-term survival after CPR in ICU patients. In patients surviving 24 h after CPR, initiation of enteral nutrition within 48 h and maintenance of normoxia were associated with a positive outcome.

Intestine-Specific Mttp Deletion Increases the Severity of Experimental Colitis and Leads to Greater Tumor Burden in a Model of Colitis Associated Cancer

Background

Gut derived lipid factors have been implicated in systemic injury and inflammation but the precise pathways involved are unknown. In addition, dietary fat intake and obesity are independent risk factors for the development of colorectal cancer. Here we studied the severity of experimental colitis and the development of colitis associated cancer (CAC) in mice with an inducible block in chylomicron secretion and fat malabsorption, following intestine-specific deletion of microsomal triglyceride transfer protein (Mttp-IKO).

Methodology/Principal Findings

Mttp-IKO mice exhibited more severe injury with ∼90% mortality following dextran sodium sulfate (DSS) induced colitis, compared to <20% in controls. Intestinal permeability was increased in Mttp-IKO mice compared to controls, both at baseline and after DSS administration, in association with increased circulating levels of TNFα. DSS treatment increased colonic mRNA expression of IL-1β and IL-17A as well as inflammasome expression in both genotypes, but the abundance of TNFα was selectively increased in DSS treated Mttp-IKO mice. There was a 2-fold increase in colonic tumor burden in Mttp-IKO mice following azoxymethane/DSS treatment, which was associated with increased colonic inflammation as well as alterations in cytokine expression. To examine the pathways by which alterations in fatty acid abundance might interact with cytokine signaling to regulate colonic epithelial growth, we used primary murine myofibroblasts to demonstrate that palmitate induced expression of amphiregulin and epiregulin and augmented the increase in both of these growth mediators when added to IL-1βor to TNFα.

Conclusions

These studies demonstrate that Mttp-IKO mice, despite absorbing virtually no dietary fat, exhibit augmented fatty acid dependent signaling that in turn exacerbates colonic injury and increases tumor formation.

Chronic alcohol ingestion increases mortality and organ injury in a murine model of septic peritonitis

Background

Patients admitted to the intensive care unit with alcohol use disorders have increased morbidity and mortality. The purpose of this study was to determine how chronic alcohol ingestion alters the host response to sepsis in mice.

Methods

Mice were randomized to receive either alcohol or water for 12 weeks and then subjected to cecal ligation and puncture. Mice were sacrificed 24 hours post-operatively or followed seven days for survival.

Results

Septic alcohol-fed mice had a significantly higher mortality than septic water-fed mice (74% vs. 41%, p = 0.01). This was associated with worsened gut integrity in alcohol-fed mice with elevated intestinal epithelial apoptosis, decreased crypt proliferation and shortened villus length. Further, alcohol-fed mice had higher intestinal permeability with decreased ZO-1 and occludin protein expression in the intestinal tight junction. The frequency of splenic and bone marrow CD4+ T cells was similar between groups; however, splenic CD4+ T cells in septic alcohol-fed mice had a marked increase in both TNF and IFN-γ production following ex vivo stimulation. Neither the frequency nor function of CD8+ T cells differed between alcohol-fed and water-fed septic mice. NK cells were decreased in both the spleen and bone marrow of alcohol-fed septic mice. Pulmonary myeloperoxidase levels and BAL levels of G-CSF and TFG-β were higher in alcohol-fed mice. Pancreatic metabolomics demonstrated increased acetate, adenosine, xanthine, acetoacetate, 3-hydroxybutyrate and betaine in alcohol-fed mice and decreased cytidine, uracil, fumarate, creatine phosphate, creatine, and choline. Serum and peritoneal cytokines were generally similar between alcohol-fed and water-fed mice, and there were no differences in bacteremia, lung wet to dry weight, or pulmonary, liver or splenic histology.

Conclusions

When subjected to the same septic insult, mice with chronic alcohol ingestion have increased mortality. Alterations in intestinal integrity, the host immune response, and pancreatic metabolomics may help explain this differential response.

New approaches to the study of sepsis

Models of sepsis have been instructive in understanding the sequence of events in animals and, to an extent, in humans with sepsis. Events developing early in sepsis suggest that a hyperinflammatory state exists, accompanied by a buildup of oxidants in tissues reflective of a redox imbalance. Development of immunosuppression and degraded innate and adaptive immune responses are well-established complications of sepsis. In addition, there is robust activation of the complement system, which contributes to the harmful effects of sepsis. These events appear to be associated with development of multiorgan failure. The relevance of animal models of sepsis to human sepsis and the failure of human clinical trials are discussed, together with suggestions as to how clinical trial design might be improved.

Increased plasma zonulin in patients with sepsis

INTRODUCTION

Zonulin is a eukaryotic protein structurally similar to Vibrio cholerae's zonula occludens toxin. It plays an important role in the opening of small intestine tight junctions. The loss of gut wall integrity during sepsis might be pivotal and has been described in various experimental as well as human studies. Increased levels of zonulin could be demonstrated in diseases associated with increased intestinal inflammation, such as celiac disease and type 1 diabetes. We therefore investigated the role of plasma levels of zonulin in patients with sepsis as a non-invasive marker of gut wall integrity.

MATERIALS AND METHODS

Plasma level of zonulin was measured in 25 patients with sepsis, severe sepsis or septic shock according to ACCP/SCCM criteria at the first day of diagnosed sepsis. 18 non-septic post-surgical ICU-patients and 20 healthy volunteers served as control. Plasma levels were determined by using commercially available ELISA kit. Data are given as median and interquartile range (IQR).

RESULTS

Significantly higher plasma concentration of zonulin were found in the sepsis group: 6.61 ng/mL (IQR 3.51-9.46), as compared to the to the post-surgical control group: 3.40 ng/mL (IQR 2.14-5.70) (P = 0.025), as well as to the healthy group: 3.55 ng/mL (IQR 3.14-4.14) (P = 0.008).

CONCLUSION

We were able demonstrate elevated levels of plasma zonulin, a potential marker of intestinal permeability in septic patients. Increased zonulin may serve as an additional mechanism for the observed increased intestinal permeability during sepsis and SIRS.

The endogenous bacteria alter gut epithelial apoptosis and decrease mortality following Pseudomonas aeruginosa pneumonia

The endogenous bacteria have been hypothesized to play a significant role in the pathophysiology of critical illness, although their role in sepsis is poorly understood. The purpose of this study was to determine how commensal bacteria alter the host response to sepsis. Conventional and germ-free (GF) C57Bl/6 mice were subjected to Pseudomonas aeruginosa pneumonia. All GF mice died within 2 days, whereas 44% of conventional mice survived for 7 days (P = 0.001). Diluting the dose of bacteria 10-fold in GF mice led to similar survival in GF and conventional mice. When animals with similar mortality were assayed for intestinal integrity, GF mice had lower levels of intestinal epithelial apoptosis but similar levels of proliferation and intestinal permeability. Germ-free mice had significantly lower levels of tumor necrosis factor and interleukin 1β in bronchoalveolar lavage fluid compared with conventional mice without changes in systemic cytokine production. Under conventional conditions, sepsis unmasks lymphocyte control of intestinal epithelial apoptosis, because sepsis induces a greater increase in gut apoptosis in Rag-1 mice than in wild-type mice. However, in a separate set of experiments, gut apoptosis was similar between septic GF Rag-1 mice and septic GF wild-type mice. These data demonstrate that the endogenous bacteria play a protective role in mediating mortality from pneumonia-induced sepsis, potentially mediated through altered intestinal apoptosis and the local proinflammatory response. In addition, sepsis-induced lymphocyte-dependent increases in gut epithelial apoptosis appear to be mediated by the endogenous bacteria.

The intestinal microbiota and host immune interactions in the critically ill

The gastrointestinal tract harbors a complex population of microbes that play a fundamental role in the development of the immune system and human health. Besides an important local contribution in the host defense against infections, it has become increasingly clear that intestinal bacteria also modulate immune responses at systemic sites. These new insights can be of profound clinical relevance especially for intensive care medicine where the majority of patients are treated with antibiotics, which have pervasive and long-term effects on the intestinal microbiota. Moreover, considerable progress has been made in defining the role of the intestinal microbiota in both health and disease. In this review, we highlight these aspects and focus on recent key findings addressing the role of intestinal microbiota in antimicrobial defense mechanisms and its impact on intestinal homeostasis in the critically ill.

Ischemic postconditioning during reperfusion attenuates intestinal injury and mucosal cell apoptosis by inhibiting JAK/STAT signaling activation

The present study attempts to evaluate the role of Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling in intestinal ischemia/reperfusion (I/R)-induced intestinal injury and whether immediate ischemic postconditioning ameliorates intestinal injury via attenuation of intestinal mucosal apoptosis subsequent to inhibiting JAK/STAT signaling activation. Anesthetized adult male Sprague-Dawley rats were subjected to superior mesenteric artery occlusion consisting of 60 min of ischemia and 2 h of reperfusion; sham laparotomy served as controls. Animals received either subcutaneous administration of JAK2 inhibitor (AG490, 8 mg/kg) or STAT inhibitor (rapamycin, 0.4 mg/kg) 30 min before ischemia. Ischemic postconditioning was performed by three cycles of 30-s reperfusion and 30-s ischemia initiated immediately upon reperfusion. It was found that intestinal I/R resulted in conspicuous intestinal injury evidenced by significant increases in Chiu's score, lactic acid, and diamine oxidase activity, accompanied with increases in plasma levels of 15-F2t-isoprostane, endothelin 1, and thromboxane B2, as well as increase in the intestinal tissue myeloperoxidase activity. Meanwhile, the apoptotic index and cleaved caspase 3, phosphorylated JAK2, phosphorylated STAT1, and phosphorylated STAT3 expression were significantly enhanced versus sham control. Both ischemic postconditioning and pretreatment with AG490 or rapamycin significantly attenuated all the above changes. These results indicate that JAK/STAT pathway activation plays a critical role in I/R-induced intestinal injury, which is associated with increased oxidative stress, neutrophil accumulation, intestinal mucosal apoptosis, and microcirculation disturbance. Ischemic postconditioning mediates attenuation of intestinal I/R injury, and cell apoptosis may be attributable to the JAK/STAT signaling inhibition.

Probiotics as potential biotherapeutics in the management of type 2 diabetes - prospects and perspectives

Diabetes mellitus is a looming epidemic worldwide, affecting almost all major sections of society, creating burdens on global health and economy. A large number of studies have identified a series of multiple risk factors such as genetic predisposition, epigenetic changes, unhealthy lifestyle, and altered gut microbiota that cause increased adiposity, β-cell dysfunction, hyperglycemia, hypercholesterolemia, adiposity, dyslipidaemia, metabolic endotoxemia, systemic inflammation, intestinal permeability (leaky gut), defective secretion of incretins and oxidative stress associated with type 2 diabetes (T2D). Recent studies have proposed multifactorial interventions including dietary manipulation in the management of T2D. The same interventions have also been recommended by many national and international diabetes associations. These studies are aimed at deciphering the gut microbial influence on health and disease. Interestingly, results from several genomic, metagenomic and metabolomic studies have provided substantial information to target gut microbiota by dietary interventions for the management of T2D. Probiotics particularly lactobacilli and bifidobacteria have recently emerged as the prospective biotherapeutics with proven efficacy demonstrated in various in vitro and in vivo animal models adequately supported with their established multifunctional roles and mechanism of action for the prevention and disease treatment. The dietary interventions in conjunction with probiotics - a novel multifactorial strategy to abrogate progression and development of diabetes - hold considerable promise through improving the altered gut microbial composition and by targeting all the possible risk factors. This review will highlight the new developments in probiotic interventions and future prospects for exploring probiotic therapy in the prevention and control of lifestyle diseases like T2D.

Effects of a multimodal management strategy for acute mesenteric ischemia on survival and intestinal failure

BACKGROUND & AIMS

Acute mesenteric ischemia (AMI) is an emergency with a high mortality rate; survivors have high rates of intestinal failure. We performed a prospective study to assess a multidisciplinary and multimodal management approach, focused on intestinal viability.

METHODS

In an Intestinal Stroke Center, we developed a multimodal management strategy involving gastroenterologists, vascular and abdominal surgeons, radiologists, and intensive care specialists; it was tested in a pilot study on 18 consecutive patients with occlusive AMI, admitted to a tertiary center from July 2009 to November 2011. Patients with left ischemic colitis, nonocclusive AMI, chronic mesenteric ischemia, and other emergencies were excluded. Patients received specific medical management: revascularization of viable small bowel and/or resection of nonviable small bowel; 12 patients received arterial revascularization. We evaluated the percentages of patients who survived for 30 days or 2 years, the number with permanent intestinal failure, and morbidity. Lengths and rates of intestinal resection were compared with or without revascularization, and in patients with early or late-stage disease.

RESULTS

Patients were followed up for a mean of 497 days (range, 7-2085 d); 95% survived for 30 days, 89% survived for 2 years, and 28% had morbidities within 30 days. Intestinal resection was necessary for 7 cases (39%), with mean lengths of intestinal resection of 30 cm and 207 cm, with or without revascularization, respectively (P = .03). Among patients with early or late-stage AMI, rates of resection were 18% and 71%, respectively (P = .049). Patients with early stage disease had shorter lengths of intestinal resection than those with late-stage disease (7 vs 94 cm; P = .02), and spent less time in intensive care (2.5 vs 49.8; P = .02).

CONCLUSIONS

A multidisciplinary and multimodal management approach might increase survival of patients with AMI and prevent intestinal failure.