Targeted inhibition of thrombin attenuates murine neonatal necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is an inflammatory bowel necrosis of premature infants and an orphan disease with no specific treatment. Most patients with confirmed NEC develop moderate-severe thrombocytopenia requiring one or more platelet transfusions. Here we used our neonatal murine model of NEC-related thrombocytopenia to investigate mechanisms of platelet depletion associated with this disease [K. Namachivayam, K. MohanKumar, L. Garg, B. A. Torres, A. Maheshwari, Pediatr. Res. 81, 817-824 (2017)]. In this model, enteral administration of immunogen trinitrobenzene sulfonate (TNBS) in 10-d-old mouse pups produces an acute necrotizing ileocolitis resembling human NEC within 24 h, and these mice developed thrombocytopenia at 12 to 15 h. We hypothesized that platelet activation and depletion occur during intestinal injury following exposure to bacterial products translocated across the damaged mucosa. Surprisingly, platelet activation began in our model 3 h after TNBS administration, antedating mucosal injury or endotoxinemia. Platelet activation was triggered by thrombin, which, in turn, was activated by tissue factor released from intestinal macrophages. Compared to adults, neonatal platelets showed enhanced sensitivity to thrombin due to higher expression of several downstream signaling mediators and the deficiency of endogenous thrombin antagonists. The expression of tissue factor in intestinal macrophages was also unique to the neonate. Targeted inhibition of thrombin by a nanomedicine-based approach was protective without increasing interstitial hemorrhages in the inflamed bowel or other organs. In support of these data, we detected increased circulating tissue factor and thrombin-antithrombin complexes in patients with NEC. Our findings show that platelet activation is an important pathophysiological event and a potential therapeutic target in NEC.

Gastroschisis for the Gastroenterologist: Updates on Epidemiology, Management, and Outcomes.

Gastroschisis is a common congenital abdominal wall defect, likely influenced by environmental factors in utero, with increasing prevalence in the United States. Early detection of gastroschisis in utero has become the standard with improved prenatal care and screening. There are multiple surgical management techniques, though sutureless closure is being used more frequently. Postoperative feeding difficulty is common and requires vigilance for complications, such as necrotizing enterocolitis. Infants with simple gastroschisis are expected to have eventual catch-up growth and normal development, while those with complex gastroschisis have higher morbidity and mortality. Management requires collaboration amongst several perinatal disciplines, including obstetrics, maternal fetal medicine, neonatology, pediatric surgery, and pediatric gastroenterology for optimal care and long-term outcomes.

Galectin-4 as a Novel Biomarker of Neonatal Intestinal Injury.

BACKGROUND: Neonates are at risk of gastrointestinal emergencies including necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP). Identifying biomarkers to aid in diagnosis is imperative. We hypothesized that circulating intestinal-specific protein concentrations would distinguish infants with intestinal injury from controls. AIMS: To identify serum concentrations of intestinal-specific protein(s) in infants with intestinal injury and controls. METHODS: We used an in silico approach to identify intestinal-specific proteins. We collected serum from control infants and infants with NEC or SIP and measured protein concentrations using ELISA. If baseline concentrations were near the detection limit in initial control assays, we proceeded to assess concentrations in a larger cohort of controls and infants with injury. Control infants were frequency matched to infants with injury and compared with nonparametric and mixed-effects models analysis. RESULTS: We evaluated four proteins with high intestinal expression: Galectin-4 (Gal-4), S100G, Trefoil Factor-3, and alanyl aminopeptidase. Only Gal-4 demonstrated consistent results near the lower limit of quantification in controls and was studied in the larger cohorts. Gal-4 concentration was low in 111 control infants (median 0.012 ng/ml). By contrast, Gal-4 was significantly increased at diagnosis in infants with surgical NEC and SIP (n = 14, p ≤ 0.001 and n = 8, p = 0.031) compared to matched controls, but not in infants with medical NEC (n = 32, p = 0.10). CONCLUSIONS: Of the intestinal-specific proteins evaluated, circulating Gal-4 concentrations were at the assay detection limit in control infants. Gal-4 concentrations were significantly elevated in infants with surgical NEC or SIP, suggesting that Gal-4 may serve as a biomarker for neonatal intestinal injury.

Intestinal dysbiosis and necrotizing enterocolitis: assessment for causality using Bradford Hill criteria.

In recent years, several studies have shown that premature infants who develop NEC frequently display enteric dysbiosis with increased Gram-negative bacteria for several days to weeks prior to NEC onset. The importance of these findings, for the possibility of a causal role of these bacteria in NEC pathogenesis, and for potential value of gut dysbiosis as a biomarker of NEC, is well-recognized. In this review, we present current evidence supporting the association between NEC in premature infants and enteric dysbiosis, and its evaluation using the Bradford Hill criteria for causality. To provide an objective appraisal, we developed a novel scoring system for causal inference. Despite important methodological and statistical limitations, there is support for the association from several large studies and a meta-analysis. The association draws strength from strong biological plausibility of a role of Gram-negative bacteria in NEC and from evidence for temporality, that dysbiosis may antedate NEC onset. The weakness of the association is in the low level of consistency across studies, and the lack of specificity of effect. There is a need for an improved definition of dysbiosis, either based on a critical threshold of relative abundances or at higher levels of taxonomic resolution.

Cost-effectiveness Analysis of Feeding Guidelines for Infants Following Intestinal Surgery.

OBJECTIVE: The aim of the study was to determine the cost-effectiveness of postoperative feeding guidelines to reduce complications in infants with intestinal surgery compared to standard feeding practices. METHODS: Using outcomes from a cohort study, Markov models from health care and societal perspectives simulated costs per hospitalization among infants fed via guidelines versus standard practice. Short-term outcomes included intestinal failure-associated liver disease, necrotizing enterocolitis after feeding, sepsis, and mortality. Effectiveness was measured as length of stay. The incremental cost-effectiveness ratios (ICER) compared cost over length of stay. Univariate and multivariate probabilistic sensitivity analyses with 10,000 Monte Carlo Simulations were performed. A second decision tree model captured the cost per quality-adjusted life years (QALYs) using utilities associated with long-term outcomes (liver cirrhosis and transplantation). RESULTS: In the hospital perspective, standard feeding had a cost of $31,258,902 and 8296 hospital days, and the feeding guidelines had a cost of $29,295,553 and 8096 hospital days. The ICER was $-9832 per hospital stay with guideline use. More than 90% of the ICERs were in the dominant quadrant. Results were similar for the societal perspective. Long-term costs and utilities in the guideline group were $2830 and 0.91, respectively, versus $4030 and 0.90, resulting in an ICER of $-91,756/QALY. CONCLUSION: In our models, feeding guideline use resulted in cost savings and reduction in hospital stay in the short-term and cost savings and an increase in QALYs in the long-term. Using a systematic approach to feed surgical infants appears to reduce costly complications, but further data from a larger cohort are needed.

Normative values for circulating intestinal fatty acid binding protein and calprotectin across gestational ages.

BACKGROUND: Necrotizing enterocolitis (NEC) is associated with significant morbidity and mortality. Serum biomarkers to aid diagnosis, such as intestinal fatty acid binding protein (IFABP) and calprotectin, are actively being investigated; however, the normative values of these markers among healthy premature and term infants remains unknown. We sought to identify normative values for the serum concentrations of IFABP and calprotectin across gestational (GA) and post-menstrual age. METHODS: We collected serum from infants (24-40 weeks GA) in the first week of life and at multiple time points in a sub-cohort of premature infants (24-29 weeks GA), excluding sepsis or known intestinal disease. IFABP and calprotectin were measured using ELISA. Groups were compared with descriptive statistics and mixed effects linear regression. RESULTS: One hundred twelve infants had specimens in the first week of life, and 19 premature infants had longitudinal specimens. IFABP concentration in the first week of life was low and did not differ across gestational ages. Longitudinally, IFABP increased 4% per day (P < 0.001). Calprotectin concentration in the first week of life was more variable. An inverse relationship between day of life and calprotectin level was found in the longitudinal cohort (P < 0.001). CONCLUSIONS: Serum IFABP and calprotectin fluctuate over time. Infants had low levels of IFABP during the first week of life, independent of gestational age, and levels increased longitudinally in premature infants. Calprotectin levels generally declined over time. Normative data for infants is necessary to establish meaningful cut-off levels for clinical use.

Use of Breast Milk and Other Feeding Practices Following Gastrointestinal Surgery in Infants.

OBJECTIVES: The aim of the study was to characterize the enteral feeding practices in infants after gastrointestinal surgery. METHODS: We performed a retrospective analysis of infants who underwent intestinal surgery at age <6 months who survived to be fed enterally between January 2012 and June 2017. Demographics, surgical characteristics, feeding practices, and growth-related outcomes during hospitalization, discharge, and follow-up (3, 6, and 12 months) were obtained from the electronic medical records. Descriptive statistics compared infants by their initial diagnosis. RESULTS: We reviewed 111 infants: necrotizing enterocolitis (NEC) = 21, gastroschisis = 28, atresia = 27, spontaneous intestinal perforation (SIP) = 18, and other diagnoses = 17. Most infants (77%) received mother's milk (MM) as the first postoperative feed, but this differed by diagnosis (P = 0.004). Donor milk was used in 11%, most commonly in infants with NEC and SIP. Infants with NEC were least likely to continue MM in the hospital (7%, P = 0.0014) and were more likely to receive elemental formula. Only 44% of infants received MM at discharge. After 1 year, 25% were fed MM. The majority of infants were discharged with feeding tubes (nasogastric: 35%, gastric: 23%). Although all groups had acceptable weights at discharge, infants with NEC (z score: -1.8) and SIP (z score: -1.1) showed growth failure at 3 months (z scores: -3.3, -3.2, respectively, P < 0.0001), but had appropriate gain by 1 year (z scores: -1.1, -1.7, respectively). CONCLUSIONS: Despite most infants receiving MM in the early postoperative period, <50% at discharge and only 33% at 1-year still received MM. Weight gain after discharge in infants with NEC and SIP warrants close monitoring.

Postoperative Enteral Nutrition Guidelines Reduce the Risk of Intestinal Failure-Associated Liver Disease in Surgical Infants.

OBJECTIVE: To assess the effectiveness of postoperative feeding guidelines in reducing the incidence and severity of intestinal failure-associated liver disease (IFALD) among infants. STUDY DESIGN: Two cohorts of infants <6 months old undergoing intestinal surgery were compared: preguideline (retrospective data from 2007 to 2013; n = 83) and postguideline (prospective data from 2013 to 2016; n = 81). The guidelines included greater initial enteral nutrition volumes of 20 mL/kg/d and daily feeding advancement if tolerated. The primary outcomes were incidence of IFALD (peak direct bilirubin [DB] >2 mg/dL) and severity (DB >5 mg/dL for moderate-severe). Multiple logistic regression was used to determine the odds of developing IFALD. Other outcomes were time to reach 50% and 100% goal calories from enteral nutrition and the incidence of necrotizing enterocolitis after feeding. RESULTS: The incidence of IFALD decreased from 71% to 51% (P = .031), and median peak DB decreased from 5.7 to 2.4 mg/dL (P = .001). After adjusting for diagnosis and prematurity, the odds of developing IFALD of any severity were reduced by 60% (OR 0.40, 95% CI 0.20-0.85), and the odds of developing moderate-to-severe IFALD were reduced by 72% (OR 0.28, 95% CI 0.13-0.58) with guideline use. Time to reach 50% enteral nutrition decreased from a median of 10 to 6 days (P = .020) and time to reach 100% enteral nutrition decreased from 35 to 21 days (P = .035) with guideline use. The incidence of necrotizing enterocolitis after initiating enteral nutrition did not change (5% vs 9%, P = .346). CONCLUSIONS: Implementation of feeding guidelines reduced time to reach feeding goals, significantly reducing IFALD incidence and severity.

Postoperative Feeding Guidelines Improve Outcomes in Surgical Infants.

BACKGROUND: Early introduction of enteral nutrition (EN) in postoperative infants improves intestinal adaptation, reducing the risk of intestinal failure-associated liver disease (IFALD). Our objective was to determine whether guideline use reduces feeding variability and improves outcomes in the neonatal intensive care unit (NICU). METHODS: In a cohort study, surgical infants at risk for IFALD were evaluated pre and post implementation of feeding guidelines at 2 NICUs. A total of 167 guideline infants (2013-2018) were compared with 242 historical controls (2007-2013). Adherence was measured with timing and volume of initial postoperative feed. Primary outcomes were IFALD incidence and time to reach 50% and 100% of energy from EN. Secondary outcomes were parenteral nutrition (PN) days, postoperative necrotizing enterocolitis (NEC), central line-associated bloodstream infection (CLABSI), and length of stay (LOS). RESULTS: Moderate IFALD decreased from 32% to 20% (P = .005) in the guideline group. Time to achieve 50% and 100% energy from EN was decreased from medians of 8 to 5 and 28 to 21 days, respectively (P < .001). There was an overall decrease in PN use from 41 to 29 days (P = .002), CLABSI incidence from 25% to 5% (P < .001), and LOS from 70 to 53 days (P = .030). Once stratified by diagnosis, infants with NEC showed greatest improvement and reduction in IFALD from 67% to 42% (P = .045). With no difference in postoperative NEC (P = .464). CONCLUSION: Early standardized postoperative EN guidelines in intestinal-surgery infants was associated with improved outcomes, including faster achievement of feeding goals and reduced IFALD severity, especially in infants with NEC.

A Central Role for Lipocalin-2 in the Adaptation to Short-Bowel Syndrome Through Down-Regulation of IL22 in Mice.

BACKGROUND & AIMS: In short-bowel syndrome (SBS), inadequate intestinal adaptation is responsible for the majority of complications, including sepsis, liver failure, and death. In this study, we sought to further delineate the adaptive response to identify potential therapeutic targets. METHODS: We performed a 75% small-bowel resection (SBR) or sham operation on C57Bl/6J wild-type (WT), lipocalin-2 (LCN2)-/-, and interleukin 22 (IL22)-/- mice. Exogenous IL22 was administered to SBR WT mice. Cecal fecal matter from SBR WT and SBR LCN2-/- mice were transplanted into germ-free mice. Intestinal permeability, inflammation, proliferation, and the microbiome were evaluated 1 week after surgery. CD4+IL22+ laminal propria lymphocytes were sorted by flow cytometry. Naïve T cells were polarized to T-helper cells with or without LCN2. RESULTS: A 75% SBR in a mouse re-creates the increased intestinal permeability, enterocyte proliferation, and intestinal dysbiosis seen in SBS. LCN2 expression increases after 75% SBR, and this increase can be abrogated with broad-spectrum antibiotic treatment. LCN2-/- mice have less intestinal inflammation, increased IL22 expression, and greater adaptation as evidenced by less intestinal permeability, increased carbohydrate enzyme expression, less weight loss, and less dysbiosis after 75% SBR than WT mice. The proinflammatory and anti-adaptive effects of LCN2 can be transferred to germ-free mice via a fecal transplant. Administration of exogenous IL22 improves adaptation and restores the normal microbiome after 75% SBR in WT mice. CONCLUSIONS: LCN2 promotes inflammation and slows intestinal adaptation through changes in the microbiome and IL22 inhibition in a mouse SBS model. Strategies to reduce LCN2 may offer novel therapeutic approaches to enhance adaptation in SBS.

New insights into the role of fatty acids in the pathogenesis and resolution of inflammatory bowel disease.

Dietary and endogenously modified lipids modulate inflammation by functioning as intra- and intercellular signaling molecules. Proinflammatory lipid mediators such as the eicosanoids compete against the signaling actions of newly discovered modified fatty acids that act to resolve inflammation. In inflammatory bowel disease, multiple aberrancies in lipid metabolism have been discovered, which shed further light on the pathogenesis of intestinal inflammation. Mechanisms by which lipids modulate inflammation, abnormalities of lipid metabolism in the setting of inflammatory bowel disease, and potential therapeutic application of lipid derivatives in this setting are discussed.