Enteral citrulline supplementation versus placebo on SOFA score on day 7 in mechanically ventilated critically ill patients: the IMMUNOCITRE randomized clinical trial.

BACKGROUND: Restoring plasma arginine levels through enteral administration of L-citrulline in critically ill patients may improve outcomes. We aimed to evaluate whether enteral L-citrulline administration reduced organ dysfunction based on the Sequential Organ Failure Assessment (SOFA) score and affected selected immune parameters in mechanically ventilated medical intensive care unit (ICU) patients. METHODS: A randomized, double-blind, multicenter clinical trial of enteral administration of L-citrulline versus placebo for critically ill adult patients under invasive mechanical ventilation without sepsis or septic shock was conducted in four ICUs in France between September 2016 and February 2019. Patients were randomly assigned to receive enteral L-citrulline (5 g) every 12 h for 5 days or isonitrogenous, isocaloric placebo. The primary outcome was the SOFA score on day 7. Secondary outcomes included SOFA score improvement (defined as a decrease in total SOFA score by 2 points or more between day 1 and day 7), secondary infection acquisition, ICU length of stay, plasma amino acid levels, and immune biomarkers on day 3 and day 7 (HLA-DR expression on monocytes and interleukin-6). RESULTS: Of 120 randomized patients (mean age, 60 ± 17 years; 44 [36.7%] women; ICU stay 10 days [IQR, 7-16]; incidence of secondary infections 25 patients (20.8%)), 60 were allocated to L-citrulline and 60 were allocated to placebo. Overall, there was no significant difference in organ dysfunction as assessed by the SOFA score on day 7 after enrollment (4 [IQR, 2-6] in the L-citrulline group vs. 4 [IQR, 2-7] in the placebo group; Mann‒Whitney U test, p = 0.9). Plasma arginine was significantly increased on day 3 in the treatment group, while immune parameters remained unaffected. CONCLUSION: Among mechanically ventilated ICU patients without sepsis or septic shock, enteral L-citrulline administration did not result in a significant difference in SOFA score on day 7 compared to placebo. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT02864017 (date of registration: 11 August 2016).

Plasma citrulline after small bowel transplantation: effect of time from transplantation, acute cellular rejection, and renal failure.

BACKGROUND: Plasma citrulline concentration (CIT) depends on its synthesis by enterocytes and its catabolism by renal tubules. To evaluate CIT applicability as a marker of acute cellular rejection (ACR) after intestinal transplantation (ITx), CIT was investigated according to time from ITx, episodes of ACR, and creatinine clearance (CrCl). METHODS: Twenty-four adult ITx recipients were prospectively studied. The results were compared with those of 19 healthy controls (HCs) and of 29 patients with chronic renal failure (CRF). RESULTS: In ITx recipients, CIT was lower than in HCs during the first two postoperative weeks; it then progressively increased and reached the range observed in HCs, approximately between the 31st and the 45th postoperative day. A positive association with postoperative days (R = 0.63; p < 0.0001) and a negative association with CrCl (R = -0.57; p < 0.0001) were observed. CIT was higher in patients with CRF than in HCs (p < 0.0001). CIT sensitivity and specificity in detecting ACR after the 45th postoperative day were 38% and 83%, using CIT threshold observed in HCs, and 69% and 77%, respectively, using CIT threshold adjusted for CRF degree. CONCLUSIONS: Adjusting CIT threshold for CRF degree almost doubled the sensitivity of CIT as a non-invasive marker of ACR in ITx recipients.

Plasma citrulline concentration and plasma LPS detection among critically ill patients a prospective observational study.

PURPOSE: Gut can be a source of sepsis but sepsis itself can induce gut dysfunction. We aimed to study whether plasma citrulline, a marker of enterocyte mass, was correlated with plasma lipopolysaccharide, a potential marker of bacterial translocation among critically ill patients. MATERIALS AND METHODS: Critically ill patients admitted to the ICU. Plasma citrulline and plasma LPS concentration and activity were measured at ICU admission. Patients were compared according to the presence of sepsis at ICU admission. RESULTS: 109 critically ill patients, with SOFA score 8 [6-12], were prospectively included. Sixty six patients (61%) had sepsis at ICU admission. There was no correlation between plasma citrulline concentration and plasma LPS concentration or activity. However, sepsis at ICU admission was associated with a lower plasma citrulline concentration (13.4 µmol.L-1 vs 21.3 µmol.L-1, p = 0.02). Plasma LPS activity was significantly higher among patients with abdominal sepsis compared to patients with extra-abdominal sepsis (1.04 EU/mL vs 0.63, p = 0.01). CONCLUSIONS: Plasma citrulline is not associated with the level of plasma LPS but is strongly decreased among septic patients. Detection of LPS is ubiquitous among critically ill patients but abdominal sepsis is associated with increased plasma LPS activity compared to extra-abdominal sepsis.

Reduced plasma citrulline levels in low birth weight infants with necrotizing enterocolitis.

BACKGROUND: Citrulline, a nonprotein amino acid, is an intermediate of the urea cycle and synthesized in small intestine. Lower plasma citrulline levels were associated with reduced function of enterocytes. Necrotizing enterocolitis (NEC) causes high morbidity and mortality, and leads impaired intestinal functions. METHODS: Plasma citrulline levels of neonates with a gestational age <32 weeks and ≤1,500 gm who developed NEC stage II/III were measured by high-performance liquid chromatography. RESULTS: We enrolled 36 preterm infants including 20 with NEC and 16 controls. Median citrulline levels of NEC and control groups were 8.6 and 20.18 µmol/l (P < 0.05), and cut off level of citrulline was 13.15 µmol/l with a sensitivity of 80% and a specificity of 82%. Median arginine levels of NEC and control groups were 22.02 and 39.89 µmol/l (P < 0.05), and cut off level of arginine was 28.52 µmol/l with a sensitivity of 70% and a specificity of 75%. Blood sampling day, gender, parenteral, and enteral nutrition did not affect the amino acid levels. CONCLUSION: We found lower plasma citrulline and arginine levels in preterm infants with NEC. Further studies are needed to determine most appropriate levels to predict recovery and prognosis of NEC, and treatment options with these amino acids in preterm infants.

Effects of glepaglutide, a long-acting glucagon-like peptide-2 analog, on intestinal morphology and perfusion in patients with short bowel syndrome: Findings from a randomized phase 2 trial.

BACKGROUND: The proadaptive effects of glucagon-like peptide-2 (GLP-2) include stimulation of intestinal mucosal growth as well as intestinal blood flow and angiogenesis. We have recently reported that daily subcutaneous injections of glepaglutide, a long-acting GLP-2 analog, improved intestinal absorptive function in patients with short bowel syndrome (SBS). As secondary and exploratory end points, the effects of glepaglutide on intestinal morphology and perfusion are reported. METHODS: The following assessments were done in 18 patients with SBS in a randomized, crossover, dose-finding, phase 2 trial before and after three weeks of treatment with glepaglutide: plasma citrulline and mucosa biopsies to assess changes in (1) intestinal morphology by immunohistochemistry and (2) gene expressions associated with absorption, proliferation, and markers of tight-junction integrity by quantitative polymerase chain reaction. Intestinal perfusion was assessed in stoma nipples by laser speckle contrast imaging and quantitative fluorescence angiography with indocyanine green. RESULTS: In the 1- and 10-mg dose groups, glepaglutide significantly increased plasma citrulline by 15.3 µmol/L (P = 0.001) and 15.6 µmol/L (P = 0.001), respectively. Trends toward an increase in villus height, crypt depth, and epithelium height were seen in the same groups. No significant changes were seen in gene expressions or intestinal perfusion. CONCLUSION: The increase in plasma citrulline and the morphological improvements may partly account for improvement in the intestinal absorptive function. However, the finding of a stability in perfusion after three weeks of treatment with glepaglutide may have been preceded by a more profound acute-phase increase in intestinal perfusion at treatment initiation.

A multicentric prospective observational study of diagnosis and prognosis features in ICU mesenteric ischemia: the DIAGOMI study.

BACKGROUND: Non-occlusive mesenteric ischemia (NOMI) is a challenging diagnosis and is associated with extremely high mortality in critically ill patients, particularly due to delayed diagnosis and when complicated by intestinal necrosis. Plasma citrulline and intestinal-fatty acid binding protein (I-FABP) have been proposed as potential biomarkers, but have never been studied prospectively in this setting. We aimed to investigate diagnostic features, the accuracy of plasma citrulline and I-FABP to diagnose NOMI and intestinal necrosis as well as prognosis. METHODS: We conducted a prospective observational study in 3 tertiary ICU centers in consecutive patients with NOMI suspicion defined by at least two inclusion criteria among: new-onset or worsening circulatory failure, gastrointestinal dysfunction, biological signs and CT-scan signs of mesenteric ischemia. Diagnosis features and outcomes were compared according to NOMI, intestinal necrosis or ruled out diagnosis using stringent classification criteria. RESULTS: Diagnosis of NOMI was suspected in 61 patients and confirmed for 33 patients, with intestinal necrosis occurring in 27 patients. Clinical digestive signs, routine laboratory results and CT signs of mesenteric ischemia did not discriminate intestinal necrosis from ischemia without necrosis. Plasma I-FABP was significantly increased in presence of intestinal necrosis (AUC 0.83 [0.70-0.96]). A threshold of 3114 pg/mL showed a sensitivity of 70% [50-86], specificity of 85% [55-98], a negative predictive value of 58% [36-93] and a positive predictive value 90% [67-96] for intestinal necrosis diagnosis. When intestinal necrosis was present, surgical resection was significantly associated with ICU survival (38.5%), whereas no patient survived without necrosis resection (HR = 0.31 [0.12-0.75], p = 0.01). CONCLUSION: In critically ill patients with NOMI, intestinal necrosis was associated with extremely high mortality, and increased survival when necrosis resection was performed. Elevated plasma I-FABP was associated with the diagnosis of intestinal necrosis. Further studies are needed to investigate plasma I-FABP and citrulline performance in less severe forms of NOMI.

Variation of plasma citrulline as a predictive factor for weaning off long-term parenteral nutrition in children with neonatal short bowel syndrome.

BACKGROUND & AIMS: Long-term parenteral nutrition (PN) is the mainstay of the therapeutic strategy in intestinal failure (IF) due to neonatal short bowel syndrome (SBS). Our aim was to identify prognostic factors for PN weaning and to assess if measuring plasma citrulline concentrations over time could account for the intestinal adaptation in progress. METHODS: This retrospective study included children with neonatal SBS with surgical measurement of the residual bowel length and repeated plasma citrulline assessments during a 4-year follow-up. The degree of IF was assessed by the PN dependency index (PN caloric intake/Resting energy expenditure). The analysis was carried out according to SBS anatomical groups: end-jejunostomy (type 1), jejuno-colic (type 2) and jejuno-ileal anastomosis (type 3). RESULTS: Fifty-five patients (8 type 1, 27 type 2, 20 type 3) were included. None of the patients with SBS type 1, 11 (41%) with type 2 and 11 (55%) with type 3 were weaned off during the follow-up period. Plasma citrulline levels significantly increased with time in patients who were finally weaned off PN; conversely, the levels did not consistently increase in patients who were still on PN at the end of the study period. There was an inverse relationship between plasma citrulline levels and the PN dependency index. The increasing citrulline levels had a positive effect on the probability of weaning, 2.7 times higher for each point increase in citrulline. No significant effect of age and residual bowel length at baseline was found. CONCLUSION: The increased plasma citrulline level over time in addition to the SBS anatomical type is a reliable marker for subsequent PN weaning. The prediction of PN weaning assessed solely by the residual bowel length or a single measurement of citrulline is insufficient and should also take into account the anatomical type of SBS and repeated measurements of plasma citrulline levels.

Evaluation of the Utility of Amino Acid Citrulline as a Surrogate Metabolomic Biomarker for the Diagnosis of Celiac Disease.

INTRODUCTION: Citrulline is regarded as a biomarker for celiac disease (CD). Its utility for assessment and evaluation of additive predictive value for latent, potential CD and first degree relatives (FDRs) needs exploration. METHOD: Consecutive 558 index cases diagnosed as per European Society for Pediatric Gastroenterology and Nutrition (ESPGHAN) 2012 guidelines and their 1565 FDRs were evaluated over five and half year period. Serology negative FDRs at initial visit and follow ups were served as controls. HLA typing for DQ2 and DQ8 genotypes, along with plasma and dried blood spot (DBS) filter paper citrulline were evaluated. RESULTS: Median plasma citrulline values were 20.1 and 37.33 µMol/l in cases and controls (P < .001). Cut off values for Marsh grade 3a, 3b, and 3c were 35.0, 32.8, 25.26 µMol/l in CD patients and 36.51, 30.10, 25.26 µMol/l in biopsy proven FDR. Increasing trends of plasma citrulline levels with decreasing tTG-IgA levels were observed on follow up. Low plasma citrulline levels were observed with HLA DQ 2.5 genotype (P < .05). Agreement between DBS and plasma citrulline was 94.8%. CONCLUSION: Citrulline is a good surrogate biomarker for identification of histopathological grade of damage, extent of mucosal recovery and has negative correlation with tTG-IgA. It identifies the silent and latent phase of CD. DBS citrulline provides adequate information and can be used for monitoring CD patients at remote locations.

Plasma Citrulline Concentrations in Neonates With or Without Gastrointestinal Disease During Periods of Parenteral and Enteral Nutrition.

INTRODUCTION: Citrulline is synthesized primarily in enterocytes. Retrospective work revealed higher plasma concentrations in patients without gastrointestinal (GI) disease than in those with GI disease, regardless of bowel resection, leading us to speculate whether it could be used as a marker of gut function prospectively. Our purpose was to analyze plasma citrulline in these patients, comparing a period of exclusive parenteral nutrition (PN) vs both PN and enteral nutrition (PN/EN). METHODS: Premature neonates were included in this study. Plasma samples were collected during 2 periods, PN and PN/EN. They were classified into groups: patients without GI disease (Group 1), patients with GI disease without resection (Group 2), and patients with GI disease and resection (Group 3). Plasma was analyzed by high-performance liquid chromatography and tandem mass spectrometry (LC-MS/MS). Data were described as median with ranges. RESULTS: Fifty patients were recruited for this study, from which 164 samples were obtained and analyzed by LC-MS. Median plasma citrulline concentrations were 12.3 (5.6-39.4) µmol/L, 14.9 (6.8-39.8) µmol/L, and 10.8 (2.0-23.6) µmol/L for Groups 1, 2, and 3, respectively. After Bonferroni correction, only Group 3 had a significantly different median from the others. No differences were observed within periods of nutrition (PN vs PN/EN). Postconceptual age (PCA), among others, was assessed to determine differences for which the former demonstrated significance. CONCLUSION: Premature neonates with bowel resection had lower plasma citrulline concentrations, confirming its role as gut mass marker, though without differences during transitional feeding. PCA may affect expression of this protein.

Impact of the route of nutrition on gut mucosa in ventilated adults with shock: an ancillary of the NUTRIREA-2 trial.

PURPOSE: The effects of the route of nutrition on the gut mucosa of patients with shock are unclear. Plasma citrulline concentration is a marker of enterocyte mass, and plasma intestinal fatty acid binding protein (I-FABP) concentration is a marker of enterocyte damage. We aimed to study the effect of the route of nutrition on plasma citrulline concentration measured at day 3 of nutrition. MATERIALS AND METHODS: Ancillary study of the NUTRIREA-2 trial. Ventilated adults with shock were randomly assigned to receive enteral or parenteral nutrition. Enterocyte biomarkers were measured at baseline, day 3, and day 8 of nutrition. RESULT: A total of 165 patients from 13 French ICUs were included in the study: 85 patients in the enteral group and 80 patients in the parenteral group. At baseline, plasma citrulline was low without difference between groups (12.2 µmol L-1 vs 13.3 µmol L-1). At day 3, plasma citrulline concentration was higher in the enteral group than in the parenteral group (18.7 µmol L-1 vs 15.3 µmol L-1, p = 0.01). Plasma I-FABP concentration was increased at baseline, without difference between groups (245 pg mL-1 vs 244 pg mL-1). Plasma I-FABP concentration was higher in the enteral group than in the parenteral group at day 3 and day 8 (158 pg mL-1 vs 50 pg mL-1, p = 0.005 and 225 pg mL-1 vs 50 pg mL-1, p = 0.03). CONCLUSION: Plasma citrulline concentration was higher after 3 days of enteral nutrition than after 3 days of parenteral nutrition. This result raises the question of the possibility that enteral nutrition is associated with a more rapid restoration of enterocyte mass than parenteral nutrition.

Assessment of intestinal malabsorption.

Significant efforts have been made in the last decade to either standardize the available tests for intestinal malabsorption or to develop new, more simple and reliable techniques. The quest is still on and, unfortunately, clinical practice has not dramatically changed. The investigation of intestinal malabsorption is directed by the patient's history and baseline tests. Endoscopy and small bowel biopsies play a major role although non-invasive tests are favored and often performed early on the diagnostic algorithm, especially in paediatric and fragile elderly patients. The current clinically available methods and research tools are summarized in this review article.

Recent advances in the management of pediatric intestinal failure.

Intestinal failure is a chronic condition in which the intestinal tract has lost most of its function. Prognosis depends on the severity and underlying etiologies. Although many patients survive under parenteral nutrition support, they often suffer from fatal complications such as progressive cholestasis and frequent sepsis. In addition, to decide the proper time to refer selected patients to bowel transplantation remains difficult. A noninvasive biomarker developed to evaluate functional enterocyte mass and the extent of intestinal adaptation is plasma citrulline level. It is shown that serum citrulline correlates with small bowel length, oral tolerance, and parenteral nutrition dependency. Recent evidence has revealed that the use of fish oil containing lipid emulsions to substitute traditional soybean-based formula may reverse a patient's cholestasis and improve lipid profiles. A new method used to prevent catheter-related bloodstream infection is ethanol lock therapy. With both antimicrobial and fibrinolytic activities, studies have shown that ethanol locks can effectively decrease catheter infection and replacement rate with no known resistance reported. As part of intestinal rehabilitation, auxiliary surgeries such as longitudinal intestinal lengthening and tailoring, serial transverse enteroplasty, and tapering enteroplasty can be beneficial for selected patients before bridging to bowel transplantation. With the introduction of these new medical and surgical modalities, patients with intestinal failure are having better outcomes than in the past.