Up-regulation of macrophage migration inhibitory factor in infants with acute neonatal necrotizing enterocolitis

Difference in macrophage migration inhibitory factor between preterm and term newborns and associating clinical factors: Preliminary study

This study aimed to investigate the macrophage migration inhibitory factor (MIF) and associated clinical factors in neonates. Clinical information and blood samples were obtained from 77 neonates. Clinical details were reviewed from medical records, and MIF was measured by enzyme-linked immunosorbent assay using blood samples acquired within a week after birth. Statistical analyses were performed between plasma MIF concentration and clinical factors. Among the 77 newborn infants, 25 were born at <34 weeks of gestation (preterm), 25 at 34 to 37 weeks (late preterm), and 27 at term gestation. The mean MIF was 9849.5 ± 7187.8 pg/mL in preterm, 5718.7 ± 4596.4 in late preterm, and 5361.1 ± 3895.7 in term infants (P = .016). Among 25 preterm infants born at <34 weeks of gestation, MIF was significantly higher in infants with necrotizing enterocolitis (NEC, 19,478.6 ± 8162.4 pg/mL, n = 5) than that in infants without NEC (feeding intolerance 7173.7 ± 4203.0 pg/mL, n = 12 and others 7844.9 ± 5311.2 pg/mL, n = 8, P = .020). Elevated plasma MIF levels in the transitional period were significantly associated with preterm birth before 34 weeks of gestation and the development of NEC.

Umbilical cord levels of macrophage migration inhibitory factor in neonatal respiratory distress syndrome

Background/aim

We aimed to evaluate the association of the umbilical cord macrophage migration inhibitory factor (MIF) with the respiratory distress syndrome (RDS) in preterm infants.

Materials and methods

A total of eighty six preterm infants (38 with RDS and 48 without RDS) were involved in the study. ELISA is the technique assaying MIF values.

Results

The mean of the infants’ gestational ages and birth weights were significantly different (P = 0.0001). There were no significant differences in sex, delivery mode or exposure to antenatal steroid among the groups (P > 0.05). Umbilical cord MIF levels of the infants were not correlated with gestational age and birth weight (Spearman’s rho = –0.22 and 0.28 respectively, P > 0.05). There was no statistically significant difference in umbilical cord MIF levels of infants whether or not they were administered antenatal steroid (median:17.88 vs. median:17.60, Mann–Whitney U test, P = 0.42). Cord serum MIF levels were higher (mean, 17.09 ± 5.86 ng/mL) in the RDS group than in the non-RDS group (mean, 14.72 ± 4.18 ng/mL) (P = 0.005).

Conclusion

This study shows that, MIF level is higher in the cord blood of the infants with RDS than of the infants without RDS. This supports that MIF expression begins in prior to the birth of the preterm infants and MIF has enhancing impact on the lung development of premature babies. With future studies, the assessment of the cord MIF levels at the bedside may be beneficial for the diagnosis and treatment of RDS, and taking actions to prevent long-term consequences.

Effect of packed red blood cell transfusion on IL-8 and sICAM-1 in premature neonates at different postnatal ages

BACKGROUND

Transfusion-related immunomodulation (TRIM) has been described in adults; however, its existence in neonates is not confirmed. The generation of TRIM is attributed to increased concentrations of IL-8, sICAM-1 and other pro-inflammatory cytokines. This study aimed to monitor changes in IL-8, sICAM-1 as markers for TRIM in premature infants at different postnatal ages.

METHODS

Preterm infants with a gestational age between 28 and 32 weeks who were receiving PRBC transfusion during the first 28 days of life were included in the study. Infants were stratified into two groups according to their postnatal age: Group 1 with postnatal ages of (0-14) days and Group 2 of (15-28) days. The concentrations of IL-8 and sICAM-1 were measured by enzyme-linked immunosorbent assay (ELISA) before transfusion, 6 h after the end of transfusion and in the donor's PRBCs bag immediately before infusion into the baby.

RESULTS

IL-8 concentration in the PRBCs bags correlated with post-transfusion level in Group 2 (r = 0.59, p = 0.002) but not in Group 1 (r = 0.39, p = 0.06). sICAM-1 concentration in the bag correlated with infants'concentrations in neither group. In Group 1, pre-transfusion concentrations of both cytokines (IL-8 and sICAM-1) did not correlate whereas post-transfusion concentrations did correlate (r = -0.09, p = 0.68 and r = 0.4, p = 0.05 respectively). In Group 2, the concentrations of both cytokines did not correlate with each other during pre-transfusion (r = 0.11, p = 0.58) as well as post-transfusion (r = 0.12, p = 0.56). There was no significant increase in either cytokines after transfusion in each group.

CONCLUSION

This study showed positive correlation between IL-8 concentration in the transfusion bag and post transfusion in Group 2 infants which could be attributed to passive transmission from the bags. This study does not support an immune modulatory effect for packed RBC in preterm infants.

A murine neonatal model of necrotizing enterocolitis caused by anemia and red blood cell transfusions

Necrotizing enterocolitis (NEC) is an idiopathic, inflammatory bowel necrosis of premature infants. Clinical studies have linked NEC with antecedent red blood cell (RBC) transfusions, but the underlying mechanisms are unclear. Here we report a neonatal murine model to investigate this association. C57BL/6 mouse pups rendered anemic by timed phlebotomy and then given RBC transfusions develop NEC-like intestinal injury with prominent necrosis, inflammation, and submucosal edema/separation of the lamina propria in the ileocecal region and colon within 12-24 h. The anemic intestine is infiltrated by inflammatory macrophages, which are activated in situ by RBC transfusions via a Toll-like receptor (TLR)-4-mediated mechanism and cause bowel injury. Chelation of RBC degradation products with haptoglobin, absence of TLR4, macrophage depletion, and inhibition of macrophage activation is protective. Intestinal injury worsens with increasing severity and the duration of anemia prior to transfusion, indicating a need for the re-evaluation of current transfusion guidelines for premature infants.

Curcumin and Intestinal Inflammatory Diseases: Molecular Mechanisms of Protection

Intestinal inflammatory diseases, such as Crohn’s disease, ulcerative colitis, and necrotizing enterocolitis, are becoming increasingly prevalent. While knowledge of the pathogenesis of these related diseases is currently incomplete, each of these conditions is thought to involve a dysfunctional, or overstated, host immunological response to both bacteria and dietary antigens, resulting in unchecked intestinal inflammation and, often, alterations in the intestinal microbiome. This inflammation can result in an impaired intestinal barrier allowing for bacterial translocation, potentially resulting in systemic inflammation and, in severe cases, sepsis. Chronic inflammation of this nature, in the case of inflammatory bowel disease, can even spur cancer growth in the longer-term. Recent research has indicated certain natural products with anti-inflammatory properties, such as curcumin, can help tame the inflammation involved in intestinal inflammatory diseases, thus improving intestinal barrier function, and potentially, clinical outcomes. In this review, we explore the potential therapeutic properties of curcumin on intestinal inflammatory diseases, including its antimicrobial and immunomodulatory properties, as well as its potential to alter the intestinal microbiome. Curcumin may play a significant role in intestinal inflammatory disease treatment in the future, particularly as an adjuvant therapy.

FTY720 attenuates intestinal injury and suppresses inflammation in experimental necrotizing enterocolitis via modulating CXCL5/CXCR2 axis

Necrotizing enterocolitis (NEC) remains one of the leading causes of death in neonatal infants and new therapeutic strategies for NEC are urgently required. The immunomodulatory agent FTY720 has been shown to have protective effects in various inflammatory diseases. In this study, we hypothesized that treatment with FTY720 confers protection against experimental NEC. Experimental NEC was induced in five-day-old C57BL/6 neonatal mice by hyperosmolar formula feeding plus hypoxia and lipopolysaccharide (LPS) challenges. Induction of NEC resulted in substantial weight loss and high mortality compared to the control group, whereas FTY720 treatment significantly attenuated weight loss and improved survival in NEC-challenged neonatal mice. FTY720 treatment strongly ameliorated NEC-induced intestinal injury with reduced apoptosis and up-regulation of intestinal barrier proteins in the ileal tissues. Furthermore, FTY720 treatment abrogated NEC-initiated intestinal and systemic inflammation with markedly diminished inflammatory cytokines and chemokines. Moreover, FTY720 treatment suppressed NEC-activated CXCL5/CXCR2 axis with down-regulated expression of CXCL5 and CXCR2 at both mRNA and protein levels. Thus, we demonstrate that FTY720 protects neonatal mice against NEC-associated lethality by ameliorating intestinal injury and attenuating inflammation, possibly via its down-regulation of NEC-induced activation of intestinal CXCL5/CXCR2 axis.

The immunological landscape in necrotising enterocolitis

Necrotising enterocolitis (NEC) is an uncommon, but devastating intestinal inflammatory disease that predominantly affects preterm infants. NEC is sometimes dubbed the spectre of neonatal intensive care units, as its onset is insidiously non-specific, and once the disease manifests, the damage inflicted on the baby's intestine is already disastrous. Subsequent sepsis and multi-organ failure entail a mortality of up to 65%. Development of effective treatments for NEC has stagnated, largely because of our lack of understanding of NEC pathogenesis. It is clear, however, that NEC is driven by a profoundly dysregulated immune system. NEC is associated with local increases in pro-inflammatory mediators, e.g. Toll-like receptor (TLR) 4, nuclear factor-κB, tumour necrosis factor, platelet-activating factor (PAF), interleukin (IL)-18, interferon-gamma, IL-6, IL-8 and IL-1β. Deficiencies in counter-regulatory mechanisms, including IL-1 receptor antagonist (IL-1Ra), TLR9, PAF-acetylhydrolase, transforming growth factor beta (TGF-β)_1&2, IL-10 and regulatory T cells likely facilitate a pro-inflammatory milieu in the NEC-afflicted intestine. There is insufficient evidence to conclude a predominance of an adaptive Th1-, Th2- or Th17-response in the disease. Our understanding of the accompanying regulation of systemic immunity remains poor; however, IL-1Ra, IL-6, IL-8 and TGF-β₁ show promise as biomarkers. Here, we chart the emerging immunological landscape that underpins NEC by reviewing the involvement and potential clinical implications of innate and adaptive immune mediators and their regulation in NEC.

Impact of oral probiotics on neurodevelopmental outcomes in preterm infants

OBJECTIVE

The aim of the study was to evaluate the neurodevelopment outcomes of very low birth weight (VLBW) preterm infants supplemented with oral probiotics for the prevention of necrotizing enterocolitis (NEC).

METHODS

A prospective follow-up study was performed in a cohort of VLBW preterm infants enrolled in a single center randomized controlled clinical trial to evaluate the efficacy of oral probiotics for the prevention of NEC. Cognitive and neuromotor developments were assessed by using the Bayley scales of infant development II. Sensory and neurological performance was evaluated by standard techniques. The primary outcome was neurodevelopmental impairment at 18-24 months' corrected age.

RESULTS

A total of 400 infants completed the trial protocol. Of the 370 infants eligible for follow-up, 249 infants (124 in the probiotics group and 125 in the control group) were evaluated. There was no significant difference in any of the neurodevelopmental and sensory outcomes between the two groups.

CONCLUSION

Oral probiotic given to VLBW infants to reduce the incidense and severity of NEC started with the first feed did not affect neuromotor, neurosensory and cognitive outcomes at 18-24 months' corrected age.

The macrophage migration inhibitory factor -173G/C polymorphism is not significantly associated with necrotizing enterocolitis in preterm infants

BACKGROUND AND PURPOSE

Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality among premature infants. Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that has been implicated in the pathophysiology of inflammatory bowel diseases. The MIF promoter contains a functionally relevant single nucleotide polymorphism (SNP) G→C at position -173, with the MIF -173*C allele being associated with higher MIF expression in vitro and with higher MIF levels in vivo. The aim of this study was to investigate whether the G/C polymorphism at -173 of the MIF promoter is associated with the development of NEC.

METHODS

In this retrospective cohort study, 107 preterm infants (GA ≤ 32 weeks), of whom 41 had NEC (NEC Stage I n = 20, Stage II n = 3, Stage III n = 18) and 66 were not affected, were genotyped for the MIF -173 SNP. MIF genotyping was carried out by PCR and DHPLC.

RESULTS

We did not find significant differences in the prevalence of the -173G/C polymorphism and in the distribution of the -173 MIF genotype in infants with NEC compared to controls. Moreover, we did not observe an association between the polymorphism and mortality.

CONCLUSIONS

The polymorphism -173G/C of the MIF promoter does not appear to be of major importance in the pathophysiology of NEC in preterm infants.

Efficacy of different probiotic combinations on death and necrotizing enterocolitis in a premature rat model

OBJECTIVE

The aim of the present study was to investigate the most effective probiotic combinations to prevent death and necrotizing enterocolitis (NEC) in a premature rat model.

METHODS

One hundred fifty-eight premature Sprague-Dawley premature rats were enrolled. Probiotic strains Bifidobacterium bifidum, B longum, Lactobacillus acidophilus, L plantarum, and B breve were fed as a single strain or mixture with 2 or 3 strains for a total of 9 study groups; control groups received no exogenous probiotic supplement. Fecal samples were collected for 72 hours to detect probiotic strains and pathologic strains by real-time polymerase chain reaction. Colony counts of probiotic strains Escherichia coli and Klebsiella were compared between groups before and after 36 hours of the study period. The incidence of death and NEC were compared via Fisher exact test between groups.

RESULTS

The results demonstrated that L plantarum alone (P = 0.0026) and B bifidum with B longum together (P = 0.0017) were more effective in reducing NEC as compared with the control group. All of the study groups except B breve and B bifidum with B breve definitely prevented death compared with controls. B bifidum and B longum together had significantly lower mortality than the control group (P < 0.0001). Colony counts of E coli and Klebsiella in stool samples were significantly decreased in the B bifidum, B longum, and L plantarum group compared with the other study and control groups after 36 hours.

CONCLUSIONS

Administration of a mixture of probiotic strains with B bifidum and B longum was most effective in preventing death and NEC in this animal model, and these observations provide an evidence-based strategy for designing further neonatal clinical trials.

Novel treatments for NEC: keeping IBD in mind

Necrotizing enterocolitis (NEC) is an inflammatory intestinal disease of premature newborns, thought to result in part from overactivity of the innate immune system. NEC has been well-studied from the perspective of prevention; however, after the disease onset, there are limited treatment options to control its progression. This review discusses four potential therapies that target the overactive immune response in NEC: pentoxifylline, platelet activating factor modulators, glucocorticoids, and vasoactive substances. In addition, given the similar pathogenesis of NEC and inflammatory bowel disease (IBD), we propose that IBD therapies could provide promising leads for novel strategies with which to treat NEC.

Plasma cytokines and markers of endothelial activation increase after packed red blood cell transfusion in the preterm infant

BACKGROUND

Transfusion of packed red blood cells (PRBCs) saves lives in the neonatal critical care setting and is one of the most common interventions in the preterm infant. The number and volume of PRBC transfusions are associated with several major neonatal morbidities, although a direct causal link between transfusion and major neonatal morbidity is still to be proven. Transfusion-related immunomodulation (TRIM) may underlie these adverse outcomes, yet it has received little attention in the high-risk preterm infant.

METHODS

One transfusion event was studied in infants ≤28 wk gestation between 2 and 6 wk postnatal age (n = 28). Plasma inflammatory cytokines and markers of endothelial activation were measured in the infants before and 2-4 h after transfusion, as well as in the donor pack.

RESULTS

Median (range) age at transfusion was 18 (14-39) days with the pretransfusion hemoglobin level at 9.8 (7.4-10.2) g/dl. Interleukin (IL)-1β (P = 0.01), IL-8 (P = <0.001), tumor necrosis factor-α (P = 0.008), and monocyte chemoattractant protein (P = 0.01) were increased after transfusion. A similar elevation in markers of endothelial activation was seen after transfusion with increased plasma macrophage inhibitory factor (P = 0.005) and soluble intracellular adhesion molecule-1 (P = <0.001).

CONCLUSION

Production of inflammatory cytokines and immunoactivation of the endothelium observed after the transfusion of PRBCs in the preterm infant may be a manifestation of TRIM. The implications of this emerging phenomenon within the preterm neonatal population warrant further investigation.

Lactobacillus rhamnosus (LGG) regulates IL-10 signaling in the developing murine colon through upregulation of the IL-10R2 receptor subunit

The intestinal microflora is critical for normal development, with aberrant colonization increasing the risk for necrotizing enterocolitis (NEC). In contrast, probiotic bacteria have been shown to decrease its incidence. Multiple pro- and anti-inflammatory cytokines have been identified as markers of intestinal inflammation, both in human patients with NEC and in models of immature intestine. Specifically, IL-10 signaling attenuates intestinal responses to gut dysbiosis, and disruption of this pathway exacerbates inflammation in murine models of NEC. However, the effects of probiotics on IL-10 and its signaling pathway, remain poorly defined. Real-time PCR profiling revealed developmental regulation of MIP-2, TNF-α, IL-12, IL-10 and the IL-10R2 subunit of the IL-10 receptor in immature murine colon, while the expression of IL-6 and IL-18 was independent of postnatal age. Enteral administration of the probiotic Lactobacillus rhamnosus GG (LGG) down-regulated the expression of TNF-α and MIP-2 and yet failed to alter IL-10 mRNA and protein expression. LGG did however induce mRNA expression of the IL-10R2 subunit of the IL-10 receptor. IL-10 receptor activation has been associated with signal transducer and activator of transcription (STAT) 3-dependent induction of members of the suppressors of cytokine signaling (SOCS) family. In 2 week-old mice, LGG also induced STAT3 phosphorylation, increased colonic expression of SOCS-3, and attenuated colonic production of MIP-2 and TNF-α. These LGG-dependent changes in phosphoSTAT3, SOCS3, MIP-2 and TNF-α were all inhibited by antibody-mediated blockade of the IL-10 receptor. Thus LGG decreased baseline proinflammatory cytokine expression in the developing colon through upregulation of IL-10 receptor-mediated signaling, most likely due to the combined induction of phospho-STAT3 and SOCS3. Furthermore, LGG-dependent increases in IL-10R2 were associated with reductions in TNF-α, MIP-2 and disease severity in a murine model of intestinal injury in the immature colon.

Necrotizing enterocolitis in the premature infant: neonatal nursing assessment, disease pathogenesis, and clinical presentation

Necrotizing enterocolitis (NEC) remains one of the most catastrophic comorbidities associated with prematurity. In spite of extensive research, the disease remains unsolved. The aims of this article are to present the current state of the science on the pathogenesis of NEC, summarize the clinical presentation and severity staging of the disease, and highlight the nursing assessments required for early identification of NEC and ongoing care for infants diagnosed with this gastrointestinal disease. The distributions of systemic and intestinal clinical signs that are most sensitive to nursing assessment and associated with Bell Staging Criteria are presented. These descriptive data are representative of 117 cases of NEC diagnosed in low-gestational-age infants (<29 weeks' gestation). The data highlight the clinical signs most commonly observed in infants with NEC and thus provide NICU nurses an evidence-based guide for assessment and care of infants with NEC.

Lack of effects of oral probiotics on growth and neurodevelopmental outcomes in preterm very low birth weight infants

OBJECTIVE

To evaluate growth and neurodevelopmental outcomes in preterm very low birth weight (PVLBW) infants treated with oral probiotics for the prevention of necrotizing enterocolitis (NEC).

STUDY DESIGN

A prospective follow-up study was performed in a cohort of PVLBW infants enrolled in a single center with a masked randomized control trial to evaluate the efficacy of oral probiotics in preventing NEC. Growth measures included weight, length, and head circumference. Neurologic and sensory performance was evaluated with standard techniques. Psychometric parameters were measured used the Bayley Scales of Infant Development II (BSID-II). The studies were performed at 3 years corrected age. The primary outcome was death or neurodevelopmental impairment.

RESULTS

Of the 367 subjects enrolled in trial, 301 (89.9%) were evaluated (153 in the probiotics group and 148 in the control group). There were no significant differences in growth or in any of the neurodevelopmental and sensory outcomes between the 2 groups.

CONCLUSIONS

Oral probiotics given to PVLBW infants at 1 week after birth to reduce the incidence of NEC did not affect growth and neurodevelopmental and sensory outcomes at 3 years corrected age.

Cytokine levels in neonatal necrotizing enterocolitis and long-term growth and neurodevelopment

OBJECTIVE

To investigate if circulating cytokines are related to growth and neurodevelopmental outcome following necrotizing enterocolitis (NEC).

STUDY DESIGN

Pro-inflammatory cytokine levels were measured prospectively in 40 neonates and compared with neurodevelopmental outcome. Cytokine levels were measured at the onset of feeding intolerance (Group II, n = 17) or NEC (Group III, n = 10) and at weeks 2-3 in control infants (Group I, n = 13). Neurodevelopmental outcome was assessed at the age of 24-28 months. Data were analysed using descriptive statistics, non-parametric tests and Student t-test.

RESULTS

Median birth weights (range) in groups I, II and III were 1120 (525-1564) g, 1068 (650-1937) g and 1145 (670-2833) g, and median gestational ages (range) were 28 (24-35) weeks 28 (24-35) weeks and 28 (25-37) weeks respectively. NEC occurred in 10 infants. Serum IL-6 (interleukin-6) was elevated in group III, (p = 0.03). Significant developmental delay was found in 12% of the infants in Group II and 20% of the infants in Group III, but no infant in group I. Five infants in group III with NEC (50%), had head ultrasound abnormalities. At 1 year of age, growth, weight and head circumference were significantly different in Group III, however, at two years of age, only height was significantly different, p < 0.02. Although there was wide variation, neonatal cytokine levels tended to be greater in the infants later found to have abnormal cognitive and psychomotor outcomes.

CONCLUSION

This study suggests that increased serum levels of pro-inflammatory cytokines may play a role in the poor growth and neurodevelopment associated with this high-risk population.

Epithelial functions of the residual bowel after surgery for necrotising enterocolitis in human infants

OBJECTIVES

Information on epithelial functions of the residual small or colonic bowel after resection for necrotising enterocolitis (NEC) in human infants is scarce. Our aim is to evaluate epithelial functions in the intestinal resection margins of tissue obtained at bowel resection for acute NEC and consecutive stoma closure.

MATERIALS AND METHODS

Epithelial morphology, proliferation, and protein expression were (immuno)histochemically studied.

RESULTS

Acute NEC was associated with severe and mild epithelial damage varying from epithelial loss to fairly unaffected epithelium. Epithelial proliferation was increased both at acute NEC and at stoma closure. In acute NEC, lactase, glucose transporter-2 and -5 expression was down-regulated in severely affected epithelium, whereas sucrase-isomaltase and intestinal fatty acid binding protein expression was maintained. Goblet cells continued to express mucin 2 and trefoil factor 3, however, their numbers were decreased. Moreover, in acute NEC, Paneth cells were weakly lysozyme positive and were reduced in number. At stoma closure, expression of the above cell type-specific markers had completely been re-established.

CONCLUSIONS

Residual bowel after resection for acute NEC shows a disturbed epithelial proliferation/differentiation balance. Acute NEC was associated with downregulation of distinct enterocyte-specific proteins. Because of goblet cell and Paneth cell loss in acute NEC, mucosal barrier, and defense functions may be impaired.

The importance of pro-inflammatory signaling in neonatal necrotizing enterocolitis

Despite modern medical advances, necrotizing enterocolitis (NEC) remains a significant cause of morbidity and mortality in neonatal intensive care units, affecting 10% of premature neonates born weighing less than 1500 g. Although many advances have been made in the understanding of NEC, the etiology and pathophysiology remain incompletely understood, and treatment is limited to supportive care. In recent years, many studies have evaluated the inflammatory cascade that is central to the disease process, and research is ongoing into strategies to prevent and/or ameliorate neonatal NEC. In this review, we examine the key points in the signaling pathways involved in NEC, and potential strategies for prevention and treatment of this dreaded disease.

Toll-like receptor 2 is protective of ischemia-reperfusion-mediated small-bowel injury in a murine model

OBJECTIVE

In a murine model of intestinal injury, we hypothesized that Toll-like receptor 2 (TLR2), a recognition molecule for commensal bacteria, plays an important role in the development of mucosal immunity and is protective against ischemia/reperfusion injury via the modulation of both innate and acquired immunity.

DESIGN

Interventional laboratory study.

SETTING

Academic medical research center.

SUBJECTS

Four-week-old C57BL/6 wild-type (n = 12) and C57BL/6 TLR2-deficient mice (TLR2-/-) (n = 12).

INTERVENTIONS

Twenty-four mice underwent laparotomy only or laparotomy plus superior mesenteric artery occlusion (n = 6/group) for 60 mins, followed by 90 mins of recovery.

MEASUREMENTS AND MAIN RESULTS

Mid-jejunal sections were taken for histopathology and messenger RNA expression (reverse transcriptase-polymerase chain reaction, normalized to 18s and laparotomy-only controls). Intestinal injury was scored from 0 (no injury) to 4 (transmural necrosis). Statistical analyses were performed using Mann-Whitney U test and Student's t-test (p < .05 significant). TLR2-/- mice had elevated intestinal injury scores (mean +/- SEM) after ischemia/reperfusion vs. wild-type (2.17 +/- 0.40 vs. 0.67 +/- 0.33, p < .05). Intestinal cytokine messenger RNA (mean fold change +/- SEM) of interferon-gamma (0.29 +/- 0.12 vs. 3313 +/- 1710), interleukin-4 (0.25 +/- 0.13 vs. 2.70 +/- 1.08), and interleukin-6 (250.63 +/- 69.60 vs. 320,300 +/- 215,964) in TLR2-/- was significantly decreased (p < .05) after ischemia/reperfusion vs. wild-type. Tumor necrosis factor-alpha messenger RNA levels were unchanged.

CONCLUSIONS

TLR2-/- mice have a dysregulated mucosal innate immune response and fail to mount a protective response after ischemia-reperfusion compared with wild-type mice. This murine model of intestinal injury may correlate with the early postnatal course of premature infants who may have decreased TLR2 expression and/or decreased luminal commensal bacteria secondary to antibiotic therapy, thus decreasing TLR2-mediated signaling.

Mathematical modeling in necrotizing enterocolitis--a new look at an ongoing problem

Necrotizing enterocolitis (NEC) is the most common and lethal disease that affects the gastrointestinal (GI) tract of the premature infant. The etiology of NEC remains undefined. The only consistent epidemiological precursors for NEC are prematurity and enteral alimentation. Various inflammatory mediators, including tumor necrosis factor (TNF)-a, interleukin (IL)-1, IL-6, IL-8, IL-10, IL-18, platelet-activating factor (PAF), and nitric oxide (NO) have been implicated in the pathogenesis of NEC, but the kinetics and role of these agents are ill-defined. Currently, there are no biomarker predictors of NEC risk and severity. Sera or tissue from early time points in the development of the disease may help delineate early inflammatory events that predispose an individual to NEC, thus providing an interventional opportunity. We suggest that the lack of diagnostic and therapeutic modalities for NEC are due to the absence of a systems view of the disease, which in turn is hindered by a lack of sensitive physiological measurements that predict perturbations in the intestinal tissue compartment and an inability to reliably test serial samples for the presence of inflammatory mediators in small volumes and in a high-throughput manner. Computational modeling is a useful tool in the study of complex systems such as the inflammatory process. Computation models provide an "existence proof" for a given mechanism, uncover subtle inconsistencies between the underlying hypotheses and quantitative data, and force one to ask how much is known. We suggest that a properly validated and calibrated mathematical model of inflammation and its pathologic consequences in NEC will be useful for predicting the physiologic and biologic response in infants suffering from the disease.

Intestinal immune defences and the inflammatory response in necrotising enterocolitis

Necrotising enterocolitis is a devastating neonatal gastrointestinal emergency predominantly affecting low birth weight, premature infants and is accompanied by significant mortality and morbid sequelae. The pathophysiology remains obscure and the management of infants with necrotising enterocolitis has not changed since the recognition of this disease. Necrotising enterocolitis is most likely the clinical culmination of multiple different risk factors interacting with each other to produce bowel injury through a final, common inflammatory pathway. Here, we review intestinal immunity and the specific inflammatory mediators involved in this disease process.

Innate immunity in critical care

Innate and adaptive immunity are required for effective control of infection. Numerous breakthroughs have been achieved in the last 15 years with regard to the functioning of the innate immune system. This article focuses on new paradigms of microorganism recognition, discusses recently described (or rediscovered) cytokines that provide further insight into the development of sepsis, and reviews both pro- and anti-inflammatory pathways for control of infection. Finally, it discusses what has and has not worked with regard to controlling inflammatory pathways in septic patients.