Plasma Intestinal Fatty Acid-binding Protein Levels Research Articles

The Association between IL-1β and IL-18 Levels, Gut Barrier Disruption, and Monocyte Activation during Chronic Simian Immunodeficiency Virus Infection and Long-Term Suppressive Antiretroviral Therapy.

HIV-induced persistent immune activation is a key mediator of inflammatory comorbidities such as cardiovascular disease (CVD) and neurocognitive disorders. While a preponderance of data indicate that gut barrier disruption and microbial translocation are drivers of chronic immune activation, the molecular mechanisms of this persistent inflammatory state remain poorly understood. Here, utilizing the nonhuman primate model of Human Immunodeficiency Virus (HIV) infection with suppressive antiretroviral therapy (ART), we investigated activation of inflammasome pathways and their association with intestinal epithelial barrier disruption (IEBD). Longitudinal blood samples obtained from rhesus macaques with chronic SIV infection and long-term suppressive ART were evaluated for IEBD biomarkers, inflammasome activation (IL-1β and IL-18), inflammatory cytokines, and triglyceride (TG) levels. Activated monocyte subpopulations and glycolytic potential were investigated in peripheral blood mononuclear cells (PBMCs). During the chronic phase of treated SIV infection, elevated levels of plasma IL-1β and IL-18 were observed following the hallmark increase in IEBD biomarkers, intestinal fatty acid-binding protein (IFABP) and LPS-binding protein (LBP). Further, significant correlations of plasma IFABP levels with IL-1β and IL-18 were observed between 10 and 12 months of ART. Higher levels of sCD14, IL-6, and GM-CSF, among other inflammatory mediators, were also observed only during the long-term SIV + ART phase along with a trend of increase in the frequencies of activated CD14+CD16+ intermediate monocyte subpopulations. Lastly, we found elevated levels of blood TG and higher glycolytic capacity in PBMCs of chronic SIV-infected macaques with long-term ART. The increase in circulating IL-18 and IL-1β following IEBD and their significant positive correlation with IFABP suggest a connection between gut barrier disruption and inflammasome activation during chronic SIV infection, despite viral suppression with ART. Additionally, the increase in markers of monocyte activation, along with elevated TG and enhanced glycolytic pathway activity, indicates metabolic remodeling that could fuel metabolic syndrome. Further research is needed to understand the mechanisms by which gut dysfunction and inflammasome activation contribute to HIV-associated metabolic complications, enabling targeted interventions in people with HIV.

High IL-1β and IL-18 Levels Associate with Gut Barrier Disruption and Monocyte Activation During Chronic SIV Infection with Long-Term Suppressive Antiretroviral Therapy.

HIV-induced persistent immune activation is a key mediator of inflammatory comorbidities such as cardiovascular disease (CVD) and neurocognitive disorders. While a preponderance of data indicate that gut barrier disruption and microbial translocation are drivers of chronic immune activation, the molecular mechanisms of this persistent inflammatory state remain poorly understood. Here, utilizing the nonhuman primate model of HIV infection with suppressive antiretroviral therapy (ART), we investigated activation of inflammasome pathways and their association with intestinal epithelial barrier disruption and CVD pathogenesis. Longitudinal blood samples obtained from rhesus macaques with chronic SIV infection and long-term suppressive ART were evaluated for biomarkers of intestinal epithelial barrier disruption (IEBD), inflammasome activation (IL-1β and IL-18), inflammatory cytokines, and triglyceride (TG) levels. Activated monocyte subpopulations and glycolytic potential were investigated in peripheral blood mononuclear cells (PBMCs). Higher plasma levels of IL-1β and IL-18 were observed following the hallmark increase in IEBD biomarkers, intestinal fatty acid-binding protein (IFABP) and LPS-binding protein (LBP), during the chronic phase of treated SIV infection. Further, significant correlations of plasma IFABP levels with IL-1β and IL-18 were observed between 10-12 months of ART. Higher levels of sCD14, IL-6, and GM-CSF, among other inflammatory mediators, were also observed only during the long-term SIV+ART phase along with a trend of increase in frequencies of activated CD14 + CD16 + intermediate monocyte subpopulations. Lastly, we found elevated levels of blood TG and higher glycolytic capacity in PBMCs of chronic SIV-infected macaques with long-term ART. The increase in circulating IL-18 and IL-1β following IEBD and their significant positive correlation with IFABP suggest a connection between gut barrier disruption and inflammasome activation during chronic SIV infection, despite viral suppression with ART. Additionally, the increase in markers of monocyte activation, along with elevated TG and enhanced glycolytic pathway activity, indicates metabolic remodeling that could accelerate CVD pathogenesis. Further research is needed to understand mechanisms by which gut dysfunction and inflammasome activation contribute to HIV-associated CVD and metabolic complications, enabling targeted interventions in people with HIV.

Gut barrier protein levels in serial blood samples from critically ill trauma patients during and after intensive care unit stay.

In an effort to better manage critically ill patients hospitalised in the intensive care unit (ICU) after experiencing multiple traumas, the present study aimed to assess whether plasma levels of intestinal epithelial cell barrier proteins, including occludin, claudin-1, junctional adhesion molecule (JAM-1), tricellulin and zonulin, could be used as novel biomarkers. Additional potential markers such as intestinal fatty acid-binding protein (I-FABP), D-lactate, lipopolysaccharide (LPS) and citrulline were also evaluated. We also aimed to determine the possible relationships between the clinical, laboratory, and nutritional status of patients and the measured marker levels. Plasma samples from 29 patients (first, second, fifth and tenth days in the ICU and on days 7, 30 and 60 after hospital discharge) and 23 controls were subjected to commercial enzyme-linked immunosorbent assay (ELISA) testing. On first day (admission) and on the second day, plasma I-FABP, D-lactate, citrulline, occludin, claudin-1, tricellulin and zonulin levels were high in trauma patients and positively correlated with lactate, C-reactive protein (CRP), number of days of ICU hospitalisation, Acute Physiology and Chronic Health Evaluation II (APACHE II) score and daily Sequential Organ Failure Assessment (SOFA) scores (P < 0.05-P < 0.01). The results of the present study showed that occludin, claudin-1, tricellulin and zonulin proteins, as well as I-FABP, D-lactate and citrulline, may be used as promising biomarkers for the evaluation of disease severity in critically ill trauma patients, despite the complexity of the analysis of various barrier markers. However, our results should be supported by future studies.

I-FABP as a Potential Marker for Intestinal Barrier Loss in Porcine Polytrauma.

Polytrauma and concomitant hemorrhagic shock can lead to intestinal damage and subsequent multiple organ dysfunction syndrome. The intestinal fatty acid-binding protein (I-FABP) is expressed in the intestine and appears quickly in the circulation after intestinal epithelial cell damage. This porcine animal study investigates the I-FABP dynamics in plasma and urine after polytrauma. Furthermore, it evaluates to what extent I-FABP can also act as a marker of intestinal damage in a porcine polytrauma model. Eight pigs (Sus scrofa) were subjected to polytrauma which consisted of lung contusion, tibial fracture, liver laceration, and hemorrhagic shock followed by blood and fluid resuscitation and fracture fixation with an external fixator. Eight sham animals were identically instrumented but not injured. Afterwards, intensive care treatment including mechanical ventilation for 72 h followed. I-FABP levels in blood and urine were determined by ELISA. In addition, immunohistological staining for I-FABP, active caspase-3 and myeloperoxidase were performed after 72 h. Plasma and urine I-FABP levels were significantly increased shortly after trauma. I-FABP expression in intestinal tissue showed significantly lower expression in polytraumatized animals vs. sham. Caspase-3 and myeloperoxidase expression in the immunohistological examination were significantly higher in the jejunum and ileum of polytraumatized animals compared to sham animals. This study confirms a loss of intestinal barrier after polytrauma which is indicated by increased I-FABP levels in plasma and urine as well as decreased I-FABP levels in immunohistological staining of the intestine.

Is I-FABP not only a marker for the detection abdominal injury but also of hemorrhagic shock in severely injured trauma patients?

BackgroundHemorrhagic shock can lead to intestinal damage with subsequent hyperinflammation and multiple organ dysfunction syndrome (MODS). The intestinal fatty acid-binding protein (I-FABP) is solely expressed in the intestine and is released extracellulary after tissue damage. This study evaluates the validity of I-FABP as an early biomarker to detect hemorrhagic shock and abdominal injury.Patients and methodsSeverely injured patients with an Injury Severity Score (ISS) ≥ 16 points and an age ≥ 18 years, admitted from January 2010 to December 2016, were included. Overall, 26 patients retrospectively presented with hemorrhagic shock to the emergency room (ER): 8 patients without abdominal injury (“HS noAbd”) and 18 patients with abdominal injury (“HS Abd”). Furthermore, 16 severely injured patients without hemorrhagic shock and without abdominal injury (“noHS noAbd”) were retrospectively selected as controls. Plasma I-FABP levels were measured at admission to the ER and up to 3 days posttraumatic (d1-d3).ResultsMedian I-FABP levels were significantly higher in the “HS Abd” group compared with the “HS noAbd” group (28,637.0 pg/ml [IQR = 6372.4–55,550.0] vs. 7292.3 pg/ml [IQR = 1282.5–11,159.5], p < 0.05). Furthermore, I-FABP levels of both hemorrhagic shock groups were significantly higher compared with the “noHS noAbd” group (844.4 pg/ml [IQR = 530.0–1432.9], p < 0.05). The time course of I-FABP levels showed a peak on the day of admission with a subsequent decline in the post-traumatic course. Furthermore, significant correlations between I-FABP levels and clinical parameters of hemorrhagic shock, such as hemoglobin, lactate value, systolic blood pressure (SBP), and shock index, were found.The optimal cut-off level of I-FABP for detection of hemorrhagic shock was 1761.9 pg/ml with a sensitivity of 85% and a specificity of 81%.ConclusionThis study confirmed our previous observation that I-FABP might be used as a suitable early biomarker for the detection of abdominal injuries in general. In addition, I-FABP may also be a useful and a promising parameter in the diagnosis of hemorrhagic shock, because of reflecting low intestinal perfusion.

Progress towards non-invasive diagnosis and follow-up of celiac disease in children; a prospective multicentre study to the usefulness of plasma I-FABP

This prospective study investigates whether measurement of plasma intestinal-fatty acid binding protein (I-FABP), a sensitive marker for small intestinal epithelial damage, improves non-invasive diagnosing of celiac disease (CD), and whether I-FABP levels are useful to evaluate mucosal healing in patients on a gluten-free diet (GFD). Ninety children with elevated tTG-IgA titres and HLA-DQ2/DQ8 positivity were included (study group). Duodenal biopsies were taken, except in those fulfilling the ESPGHAN criteria. Plasma I-FABP levels and tTG-IgA titres were assessed sequentially during six months of follow-up. Eighty children with normal tTG-IgA titres served as control group. In 61/90 (67.8%) of the children in the study group an increased I-FABP level was found; in all these children CD diagnosis was confirmed. Interestingly, in 14/30 (46.7%) children with slightly elevated tTG-IgA titres (<10x upper limit of normal), an increased I-FABP level was found. In all these children the diagnosis of CD was confirmed histologically. After gluten elimination for six weeks I-FABP levels had decreased towards levels in the control group. Measurement of plasma I-FABP, in addition to tTG-IgA, EMA-IgA and HLAtyping, enables non-invasive diagnosing of CD in a substantial number of children, and might therefore be of value in the diagnostic approach of CD.

I-FABP is a Novel Marker for the Detection of Intestinal Injury in Severely Injured Trauma Patients.

Intestinal injury is a rare injury in multiply traumatized patients, and its diagnosis remains difficult. Delayed diagnosis of an intestinal injury increases the risk of sepsis, multiple organ failure and mortality. The intestinal fatty acid-binding protein (I-FABP) is solely expressed in the intestine and is released extracellulary after tissue damage. This study evaluates the validity of I-FABP as an early biomarker to detect an abdominal injury and particularly an injury to the intestine. Patients with an Abbreviated Injury Scale (AIS) score for abdominal body region (AIS abdomen) ≥3 were included in this study from 07/2006 to 12/2014. Of those, ten patients retrospectively had an intestinal injury (int. injury). According to the Injury Severity Score and the AIS abdomen, corresponding patients with an abdominal injury but without an intestinal injury (no int. injury) were included for matched-pair analysis. Twenty healthy volunteers served as controls. Plasma I-FABP levels were measured at admission to the emergency room and up to 10days daily (d1-d10). Median I-FABP levels were significantly higher in the "int. injury" group compared to the "no int. injury" group [2101.0pg/ml (IQR=1248.1-4117.8) vs. 351.4pg/ml (IQR=287.6-963.3), p<0.05]. Furthermore, I-FABP levels of both groups were significantly higher compared to the control group [Ctrl: 127.2pg/ml (IQR=57.4-310.6), p<0.05]. The time course of I-FABP levels showed a peak on the day of admission and a decline to the control levels in the further post-traumatic course. The development of complications such as single- or multi-organ failure, sepsis, acute respiratory distress syndrome, pneumonia and mortality was higher in the "int. injury" group; however, this difference was not statistically significant. This study confirmed our previous observation that I-FABP might be used as a suitable early biomarker for the detection of abdominal injuries in general. In addition and more specific, I-FABP may be a useful and promising parameter in the diagnosis of intestinal injuries.

Clinical Evaluation of "Shock Bowel" Using Intestinal Fatty Acid Binding Protein.

"Shock bowel" is one of the computed tomographic (CT) signs of hypotension, yet its clinical implications remain poorly understood. We evaluated how shock bowel affects clinical outcomes and the extent of intestinal epithelial damage in trauma patients by measuring the level of intestinal fatty acid binding protein (I-FABP). We reviewed the initial CT scans, taken in the emergency room, of 92 patients with severe blunt torso trauma who were consecutively admitted during a 24-month period. The data collected included CT signs of hypotension, I-FABP, feeding intolerance, and other clinical outcomes. Demographic and clinical outcomes were compared in patients with and without hemodynamic shock and shock bowel. Shock bowel was found in 16 patients (17.4%); of them 7 patients (43.8%) did not have hemodynamic shock. Certain CT signs of hypotension, namely free peritoneal fluid, contrast extravasation, small-caliber aorta, and shock bowel, were significantly more common in patients with hemodynamic shock than in patients without (P < 0.05). Injury severity score and the rate of consciousness disturbance were significantly higher in patients with shock bowel than in patients without (P < 0.05). The rate of feeding intolerance and median plasma I-FABP levels were significantly higher in patients with shock bowel than in patients without (75.0% vs. 22.4%, P < 0.001 and 17.0 ng/mL vs. 3.7 ng/mL, P < 0.001, respectively). There was no difference in mortality. In conclusion, shock bowel is not always due to hemodynamic shock. It does, however, indicate severe intestinal mucosal damages and may predict feeding intolerance.

The role of I-FABP as a biomarker of intestinal barrier dysfunction driven by gut microbiota changes in obesity.

BackgroundIntestinal fatty-acid binding protein (I-FABP) is expressed in epithelial cells of the mucosal layer of the small intestine tissue. When intestinal mucosal damage occurs, I-FABP is released into the circulation and its plasma concentration increases. In the context of obesity, the gut barrier integrity can be disrupted by dietary fat while intestinal permeability increases.ObjectiveTo investigate whether intestinal fatty acid binding protein (I-FABP) is a suitable plasma marker of intestinal injury and inflammation in obesity.MethodsTwelve male Wistar rats were randomly divided into two groups of six animals each: standard (St) and high-fat (HF) diet fed groups for 12 weeks.ResultsHF fed animals developed obesity, insulin resistance and seemed to present increased plasma levels of proinflammatory cytokines (MCP-1 and IL1β). The gut microbiota composition of these animals was also altered, with lower number of copies of Bacteroidetes, Prevotella spp. and Lactobacillus spp., in comparison with those from St diet group. Fecal lipopolysaccharide (LPS) concentrations tended to be increased in HF fed animals. Intestinal expression of TLR4 seemed to be also increased in HF fed animals suggesting that HF diet-induced dysbiosis may be behind the systemic inflammation observed. However, in contrast to other intestinal inflammatory diseases, plasma I-FABP levels were decreased in HF fed rats whereas I-FABP expression in jejunum tended to be increased.ConclusionsHF diet-induced obesity is characterized by dysbiosis, insulin resistance and systemic inflammation. In this context, plasmatic I-FABP should not be used as a marker of the intestinal barrier dysfunction and the low-grade chronic inflammatory status.

Prevention of gastrointestinal injury by using glutamine in cardiac surgery

A pilot double-blind, placebo-controlled, randomized study The aim of this study was to evaluate the efficiency of perioperative administration of glutamine to preserve intestinal integrity in patients undergoing cardiac surgery. 24 patients scheduled for elective coronary artery bypass surgery under cardiopulmonary bypass were included in this prospective, randomized, double-blind placebo controlled pilot study. 12 patients were randomized to receive glutamine (20% solution of N(2)-L-alanyl-L-glutamine) 0.4 g/kg a day, while the remaining 12 patients received an equivalent placebo dose (0.9% solution of NaCl). Infusion of glutamine/placebo was started after the induction of anesthesia and was continued for 24 hours. The primary end-point was dynamics of plasma concentration of a specific marker of intestinal damage, intestinal fatty acid binding protein (I-FABP). The secondary end-points were liver fatty acid binding protein (L-FABP), alpha glutathione s-transferase (aGST), heat shock protein 70 (HSP 70). There were no between-group differences of all the studied biochemical parameters at any stage of the study. Plasma I-FABP levels (median [25-75 percentile]) were markedly elevated during CPB and remained the same postoperatively: 962 (577-2 067) and 883 (444-1 625) г/ml 5 min after un-clamping of aorta, 2203 (888-3 429) and 1 560 (506-2 657) г/ml &lt;sup&gt;2&lt;/sup&gt; hours post-bypass, 897 (555-1 424) and 794 (505-951) г/ml 6 hours post-bypass in the GLN and control groups respectively. Perioperative administration of glutamine in dose of 0.4 g/kg a day does not appear to preserve intestinal integrity in low risk cardiac surgery patients.

Intestinal fatty acid-binding protein as a diagnostic marker for complicated and uncomplicated necrotizing enterocolitis: a prospective cohort study.

BackgroundEarly NEC symptoms are non-specific and diagnostic tests lack discriminative power. Intestinal fatty acid-binding protein (I-FABP), mainly located in small bowel enterocytes, is released into the blood following NEC-associated enterocyte disruption. Aim of this prospective cohort trial was to determine the diagnostic value of I-FABP measured in plasma (I-FABPp) and urine (I-FABPu) for the presence of NEC, to evaluate I-FABP levels during NEC development, and to assess its prognostic value for the progression from suspected to complicated disease.MethodsBetween 2010 and 2012 we prospectively enrolled neonates with suspected NEC. We measured I-FABP levels eight-hourly from onset of suspected NEC for at least 48 hours, or until surgery. NEC diagnosis was confirmed radiologically or during operation. We defined NEC as complicated if it resulted in surgery and/or death. We determined disease course and diagnostic I-FABP cut-off points.ResultsThe study comprised 37 neonates (24M, 13F), gestational age 28 (24–36) weeks, birth weight 1190 (570–2,400) grams. We found significantly higher I-FABPp and I-FABPu levels in NEC patients (n = 22) than in patients with other diagnoses (n = 15). Cut-off values for diagnosing NEC were 9 ng/mL I-FABPp and 218 ng/mL I-FABPu, with corresponding likelihood ratios (LRs) of 5.6 (95% CI 0.89–35) and 5.1 (95% CI 0.73–36), respectively. I-FABP levels were highest in the first eight hours after symptom onset and gradually decreased over time. Cut-off values for complicated disease were 19 ng/mL I-FABPp and 232 ng/mL I-FABPu, with LRs of 10 (95% CI 1.6–70) and 11 (95% CI 1.6–81), respectively.ConclusionsBoth plasma and urinary I-FABP levels specifically identify NEC in preterm infants prior to appearance of diagnostic radiological signs suggestive for NEC. Moreover, serial I-FABP measurements accurately predict development of complicated disease.

Prediction of reversibility of intestinal mucosal damage after ischemia-reperfusion injury by plasma intestinal fatty acid-binding protein levels in pigs.

The aims of this study were to elucidate the association between plasma intestinal fatty acid-binding protein (I-FABP) level and actual pathological damage of intestinal mucosa and its reversibility. An intestinal ischemia-reperfusion model was created by temporary occlusion of the descending aorta in 9 pigs which were divided into 3 groups according to the duration of visceral ischemic insult: 15-minute ischemia (n=3), 30-minute ischemia (n=3) and 60-minute ischemia (n=3). Blood samples and short segments of the jejunum for pathological examinations, including immunohistochemical staining of I-FABP, Ki-67 and E-cadherin, were taken at the beginning of the operation (T1) and 15 minutes (T2), 30 minutes (T3), 45 minutes (T4) and 60 minutes (T5) after reperfusion. Plasma I-FABP after 15 minutes of ischemia reached a peak of 1859 ± 1089 pg/ml at T3, while the level after 30 minutes of ischemia achieved a peak level of 5053 ± 1 717 pg/ml at T5. The level after 60 minutes of ischemia demonstrated a rapid increment up to 10734 ± 93 pg/ml at T3. There was a significant difference in the trend of plasma I-FABP levels between 30 minutes and 60 minutes of ischemia (p=0.01). The strongest immunohistochemical staining of the intestinal epithelium for I-FABP was observed at T4 after 30 minutes of ischemia, with the shedding of injured epithelium followed by re-epithelialisation, with sequential up-regulation of Ki67 and E-cadherin. However, the intestinal epithelium after 60 minutes of ischemia demonstrated the lack of I-FABP expression with irreversible damage. Plasma I-FABP levels may be a crucial marker to recognize the reversibility of damage of the intestinal epithelium after an ischemic insult and the level of 5000 pg/ml is considered to be the critical borderline for irreversibility, which might prevent diagnostic delay in the clinical setting.

Plasma Intestinal Fatty Acid–Binding Protein Levels Correlate With Morphologic Epithelial Intestinal Damage in a Human Translational Ischemia-reperfusion Model

Intestinal fatty acid-binding protein (I-FABP) is a useful marker in the detection of intestinal ischemia. However, more insight into the test characteristics of I-FABP release is needed. This study aimed to investigate the relationship between plasma I-FABP levels and the severity of ischemic mucosal injury, and define the clinical usefulness of systemic I-FABP following ischemia. In a human experimental model, 6 cm of the jejunum, to be removed for surgical reasons, was selectively exposed to either 15, 30, or 60 minutes of ischemia (I) followed by 30 and 120 minutes of reperfusion (R). Blood and tissue was sampled at all time points. Arteriovenous (V-A) concentration differences of I-FABP were measured. Tissue sections were stained with hematoxylin/eosin, and villus height was measured to score epithelial damage. Histologic analysis showed only minor reversible intestinal damage following 15 I and 30 I; however, severe irreversible epithelial damage was observed in the jejunum exposed to 60 I. I-FABP V-A differences paralleled the degree of tissue damage over time [7.79 (± 1.8) ng/mL, 128.6 (± 44.2) ng/mL, 463.3 (± 139.8) ng/mL for 15 I, 30 I and 60 I, respectively]. A good correlation was found between histologic epithelial damage and V-A I-FABP (r=-0.82, P<0.001). Interestingly, systemic I-FABP levels were significantly increased after 60 I of this short small intestinal segment. This study demonstrates the relationship between the duration of ischemia and the extent of tissue damage, which is reflected by I-FABP V-A plasma levels. In addition, systemic I-FABP levels appear valuable in detecting irreversible intestinal ischemia-reperfusion damage.

Dietary protein digestion and absorption are impaired during acute postexercise recovery in young men

Previously, we demonstrated that exercise can cause small intestinal injury, leading to loss of gut barrier function. The functional consequences of such exercise-induced intestinal injury on subsequent food digestion and absorption are unclear. The present study determined the impact of resistance-type exercise on small intestinal integrity and in vivo dietary protein digestion and absorption kinetics. Twenty-four young males ingested 20 g specifically produced intrinsically l-[1-(13)C]phenylalanine-labeled protein at rest or after performing a single bout of resistance-type exercise. Continuous intravenous infusions with l-[ring-(2)H5]phenylalanine were employed, and blood samples were collected regularly to assess in vivo protein digestion and absorption kinetics and to quantify plasma levels of intestinal fatty-acid binding protein (I-FABP) as a measure of small intestinal injury. Plasma I-FABP levels were increased after exercise by 35%, reaching peak values of 344 ± 53 pg/ml compared with baseline 254 ± 31 pg/ml (P < 0.05). In resting conditions, I-FABP levels remained unchanged. Dietary protein digestion and absorption rates were reduced during postexercise recovery when compared with resting conditions (P < 0.001), with average peak exogenous phenylalanine appearance rates of 0.18 ± 0.04 vs. 0.23 ± 0.03 mmol phenylalanine·kg lean body mass(-1)·min(-1), respectively. Plasma I-FABP levels correlated with in vivo rates of dietary protein digestion and absorption (rS = -0.57, P < 0.01). Resistance-type exercise induces small intestinal injury in healthy, young men, causing impairments in dietary protein digestion and absorption kinetics during the acute postexercise recovery phase. To the best of our knowledge, this is first evidence that shows that exercise attenuates dietary protein digestion and absorption kinetics during acute postexercise recovery.

Circulating Intestinal Fatty Acid-Binding Protein as an Early Marker of Intestinal Necrosis After Aortic Surgery

This study evaluated the usefulness of plasma intestinal fatty-acid binding protein (IFABP) levels in the early identification of intestinal necrosis (IN) in patients undergoing different types of aortic surgery. Intestinal compromise greatly contributes to postoperative adverse outcome. IN is the most detrimental form of intestinal compromise and is notoriously difficult to diagnose. IFABP is a small protein exclusively expressed by mature enterocytes and a promising marker of intestinal damage. Plasma IFABP concentrations were measured in blood samples taken perioperatively from 55 patients undergoing open thoracic or thoracoabdominal aneurysm repair [OR-TAA(A)], 25 patients undergoing conventional open abdominal aneurysm repair (OR-abdominal aortic aneurysm [AAA]), and 16 patients undergoing endovascular aneurysm repair (EVAR). Data were compared with perioperative changes in arterial pH and serum lactate levels. IFABP levels increased in all patients undergoing OR-TAA(A) and OR-AAA reaching peak levels shortly after surgery; 281 ± 33 to 2,298 ± 490 pg/mL (P < 0.001) and 187 ± 31 to 641 ± 176 pg/mL (P < 0.05) respectively. IFABP levels were significantly higher in patients undergoing OR-TAA(A) (P < 0.001). IFABP levels in EVAR patients remained at baseline concentrations throughout the study. Four patients [2 OR-AAA, 2 OR-TAA(A)] developed fatal postoperative intestinal ischemia on day 2 or 3. High levels of plasma IFABP at the end of surgery had 100% sensitivity and 98.1% specificity for the identification of patients developing IN. In OR-AAA patients, arterial pH and lactate levels were of additional discriminating value. Complete discrimination between patients with and without IN using plasma IFABP could be made on the first postoperative day. Analysis of plasma IFABP levels is of additional value to other current plasma markers in the diagnosis of IN, and it enables early identification of patients with IN after aortic surgery days before clinical diagnosis.

Small Intestinal Alterations in Severely Obese Hyperglycemic Subjects

Type 2 diabetes mellitus (DM2) is associated with small intestinal hyperplasia and hypertrophy in rodents. Moreover, the small intestine is increasingly acknowledged to play a role in the pathophysiology of DM2. The objective of the study was to investigate the relation between plasma markers of small intestinal function and chronic hyperglycemia in man. We conducted a cross-sectional observational study of 40 severely obese subjects with chronic hyperglycemia and 30 severely obese subjects without chronic hyperglycemia who were indicated for bariatric surgery. We assessed plasma levels of citrulline, representing small intestinal enterocyte mass, intestinal fatty acid binding protein (I-FABP), a marker of enterocyte loss, and glucagon-like peptide-2, an intestinotrophic factor, and related them to glycated hemoglobin (HbA(1c)) levels. Plasma citrulline and I-FABP levels were both significantly elevated in subjects with chronic hyperglycemia (HbA(1c) > 6.0%) compared with subjects with a normal HbA(1c) (≤ 6.0%) (citrulline, 35 ± 2.1 μm vs. 26 ± 1.4 μm, P = 0.001; I-FABP, 140 ± 22 pg/ml vs. 69 ± 14 pg/ml, P = 0.001). Moreover, plasma citrulline and I-FABP levels correlated with HbA(1c) levels (citrulline, r(s) = 0.30, P = 0.02; I-FABP, r(s) = 0.33, P = 0.005). The I-FABP to citrulline ratio was higher in subjects with an elevated HbA(1c) (4.0 vs. 3.1, P = 0.03). Plasma glucagon-like peptide-2 levels were not related to citrulline or I-FABP levels (r(s) = 0.06, P = 0.67; r(s) 0.08, P = 0.54, respectively). Chronically elevated glucose levels in obese individuals are associated with increased small intestinal enterocyte mass and increased enterocyte loss. These findings argue for the further exploration of the role of the intestine in the pathophysiology of DM2.