L-FABP and NGAL are novel biomarkers for detection of abdominal injury and hemorrhagic shock.

INTRODUCTION: Delayed diagnosis of abdominal injuries and hemorrhagic shock leads to secondary complications and high late mortality in severely traumatized patients. The liver fatty acid-binding protein (L-FABP) is expressed in intestine, liver and kidney; the neutrophil gelatinase-associated lipocalin (NGAL) in colon and kidney. We hypothesized that l-FABP is an early biomarker for abdominal injury and hemorrhagic shock and that l-FABP and NGAL are specific markers for detection of liver and/or kidney injuries. PATIENTS AND METHODS: Traumatized patients with an age ≥18 years and an abdominal injury (AISabd≥2), independently from Injury Severity Score (ISS), were prospectively included from 04/2018 to 05/2021. 68 patients had an abdominal injury ("Abd") and 10 patients had an abdominal injury with hemorrhagic shock ("HS Abd"). 41 patients without abdominal injury and hemorrhagic shock but with an ISS ≥ 25 ("noAbd") were included as control group. Four abdominal subgroups with isolated organ injuries were defined. Plasma l-FABP and NGAL levels were measured at admission (ER) and up to two days post-trauma. RESULTS: All patient groups had a median ISS≥25. In ER, median l-FABP levels were significantly higher in "HS Abd" group (1209.2 ng/ml [IQR=575.2-1780.3]) compared to "noAbd" group (36.4 ng/ml [IQR=14.8-88.5]), and to "Abd" group (41.4 ng/ml [IQR=18.0-235.5]), p<0.001. In matched-pair-analysis l-FABP levels in the group "Abd" were significantly higher (108.3 ng/ml [IQR=31.4-540.9]) compared to "noAbd" (26.4 ng/ml [IQR=15.5-88.8]), p = 0.0016. l-FABP correlated significantly with clinical parameters of hemorrhagic shock; the optimal cut-off level of l-FABP for detection was 334.3 ng/ml (sensitivity: 90%, specificity: 78%). Median l-FABP-levels were significantly higher in patients with isolated liver or kidney injuries and correlated significantly with AST, ALT and creatinine value. Median NGAL levels in the ER were significantly higher in "HS Abd" group (115.9 ng/ml [IQR=90.6-163.8]) compared to "noAbd" group (58.5 ng/ml [IQR=41.0-89.6],p<0.001) and "Abd" group (70.5 ng/ml [IQR=53.3-115.5], p<0.05). The group "Abd" showed significant higher median NGAL levels compared to "noAbd", p = 0.019. NGAL levels correlated significantly with clinical parameters of hemorrhagic shock. CONCLUSION: L-FABP and NGAL are novel biomarkers for detection of abdominal trauma and hemorrhagic shock. l-FABP may be a useful and promising parameter in diagnosis of liver and kidney injuries, NGAL failed to achieve the same.

Clinical investigation of intestinal fatty acid-binding protein (I-FABP) as a biomarker of SARS-CoV-2 infection.

OBJECTIVES: SARS-CoV-2 exhibits tropism for the gastrointestinal tract; however, lesions in enterocytes and their correlation with disease severity and patient prognosis are still unknown. METHODS: SARS-CoV-2 patients were enrolled in 5 medical centres in São Paulo, Brazil and their clinical characteristics and laboratory findings recorded. At admission, day 7 and day 14 of hospitalisation, plasma and urine samples were collected, and cytokine levels and intestinal fatty acid-binding protein (I-FABP) concentrations measured. RESULTS: COVID-19 patients displayed ≈48-, 74- and 125-fold increased urinary I-FABP levels at admission (n=283; P<0.001), day 7 (n=142; P<0.01) and day 14 (n=75; P<0.01) of hospitalisation. Critically ill patients and nonsurvivors showed higher I-FABP concentrations compared with patients with less severe illness. At admission, infected patients demonstrated enhanced production of plasma interferon (IFN)-γ and interleukin (IL)-6. The receiver operating characteristic curve suggested I-FABP as a biomarker for COVID-19 disease severity at admission (P<0.0001; Youden index=6.89; area under the curve=0.699). Patients with I-FABP ≥6.89 showed higher IL-6 and C-reactive protein levels (P<0.001) at admission and had a prolonged length of hospital stay. CONCLUSIONS: Our findings revealed damage to enterocytes in SARS-CoV-2 infection, which is associated with illness severity, poor prognosis and exacerbated inflammatory response.

Exploration of biomarkers in osteoarthritis based on bioinformatics.

ABSTRACT: Osteoarthritis (OA) seriously affects human health and brings a heavy social burden. This study aimed to identify new biomarkers involved in OA. Differential expression analysis and gene set enrichment analysis were performed on the microarray data set of OA. Identify key genes from immune-related DEGs and verify their expression in the validation set. CIBERSORT was used to analyze the infiltration of immune cells. The correlation between key genes and immune cells were conducted. A total of 1779 DEGs were identified in GSE82107. Gene set enrichment analysis results of top 4 for hallmark revealed the enrichment of DEGs were associated with genes in "HALLMARK_TNFA_SIGNALING_VIA_NFKB", "HALLMARK_EPITHELIAL_MESENCHYMAL_TRANSITION", "HALLMARK_INFLAMMATORY_RESPONSE" and "HALLMARK_HYPOXIA". A total of 108 immune-related DEGs were identified from the overlap between 2498 immune-related genes and 1779 DEGs. The expression of top 6 immune-related DEGs including ADIPOQ, FABP4, FOS, IGLC1, IGLV1-44 and leptin were measured in the validation set, the results shown that IGLC1 and IGLV1-44 might play a key role in the synovial membrane of OA. A total of 8 kinds of cells including B cells memory, Plasma cells, T cells CD4 memory resting, T cells gamma delta, natural killer cells activated, macrophages M0, Mast cells resting and Mast cells activated have significant differences in infiltration between the OA group and the control group. Besides, the expressions of IGLC1 and IGLV1-44 are highly correlated. Our results indicated that IGLC1 and IGLV1-44 may play the role of immune-related biomarkers in OA.

Proteomics of exhaled breath condensate in lung cancer and controls using data-independent acquisition (DIA): a pilot study.

Lung cancer, the leading cause of cancer mortality worldwide has a poor prognosis. To develop a non-invasive method for early lung cancer detection, exhaled breath condensate (EBC) was explored in this study. EBC samples were collected from lung cancer patients (n= 10) and healthy controls (n= 10), and a proteomic study was performed to identify potential biomarkers. Data-dependent acquisition was used to build the spectral library, and a data-independent acquisition (DIA) approach was applied for quantification of EBC proteomics. A total of 1151 proteins were identified, and several proteins were significantly upregulated in the lung cancer group compared to the control group. The Gene Ontology analysis revealed that most of the proteins were located within several organelles in the cells and were involved in binding and catalytic activity, and the Kyoto Encyclopedia Genes and Genomes results revealed that the proteins were mainly related to organismal systems and human disease. And S100A11, ANXA1, ENO1, and FABP5 might play a vital role in the EBC proteome. In summary, we demonstrated that the DIA-based quantification method was efficient in performing proteomic analysis in individual EBC samples, and some of the proteins might be novel biomarkers for lung cancer.

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

Background: Hemorrhagic 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 methods: Severely 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). Results: Median 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%. Conclusion: 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, I-FABP may also be a useful and a promising parameter in the diagnosis of hemorrhagic shock, because of reflecting low intestinal perfusion.

High expression of FABP4 and FABP6 in patients with colorectal cancer.

OBJECTIVE: To explore the relationship between FABP4 and FABP6 expression and the pathogenesis of colorectal cancer (CRC) and their potential as biomarkers in the diagnosis of CRC. METHODS: In total, 100 CRC patients and 100 controls were enrolled. The serum levels of FABP4 and FABP6 were detected by enzyme-linked immunosorbent assay (ELISA) before and 2 weeks after radical resection of CRC. The protein expressions of FABP4 and FABP6 were observed in colorectal tumor tissues and adjacent tissues by immunohistochemistry and western blot, respectively. The diagnostic performance of FABP4 and FABP6 in patients with CRC was evaluated by receiver operating characteristic (ROC) curve analysis. RESULTS: The serum levels of FABP4 and FABP6 in patients with CRC were higher than the levels in the controls before surgery (P < 0.001), and significantly decreased at 2 weeks after operation (P < 0.001). Immunohistochemistry showed that FABP4 and FABP6 were mainly distributed in the cytoplasm of human colorectal tumor tissues, and only a small amount distributed in adjacent tissues. Western blot revealed that the protein expressions of FABP4 and FABP6 were significantly higher in tumor tissues than in adjacent tissues (P < 0.001, P = 0.002, respectively). Tumors with high and low FABP4 and FABP6 expression have no significant correlation in tumor size, tumor site, distant organ and lymph node metastasis, histologic grade, lymphatic permeation, neurological invasion, vascular invasion, and Duke's and TNM classification. Multivariate logistic regression analysis showed that FABP4 and FABP6 were independent risk factors for CRC (adjusted odds ratio 1.916; 95%CI 1.340-2.492; P < 0.001; adjusted odds ratio 2.162; 95%CI 1.046, 1.078); P < 0.001, respectively). In discriminating CRC from the normal control, the optimal sensitivity of FABP4 and FABP6 were 93.20% (95%CI 87.8-96.7) and 83.70% (95%CI 76.7-89.3), respectively, while the optimal specificity of FABP4 and FABP6 were 48.8% (95%CI 39.8-57.9) and 58.4% (95%CI 49.2-67.1), respectively. When combined detection of serum carcinoembryonic (CEA) and FABP4 and FABP6, the optimal sensitivity and specificity were 61.33% (95%CI 53.0-69.2) and 79.82% (95%CI 71.3-86.8), respectively. CONCLUSION: Increased expression of FABP4 and FABP6 not only were strong risk factors for the development of CRC but could also represent a potential biomarker for CRC diagnosis in Chinese patients. Combined detection of CEA with FABP4 and FABP6 could improve the diagnostic efficacy of CRC.

Fatty acid-binding proteins: functional understanding and diagnostic implications.

PURPOSE OF REVIEW: Fatty acid-binding proteins (FABPs) are a family of small, abundant proteins with highly tissue-specific expression patterns whose different functions remain incompletely understood. The purpose of this review is to summarize recent findings regarding FABP functions and mechanisms of action, including their potential utilization as serum markers of tissue-specific metabolic diseases. RECENT FINDINGS: FABPs are important not only in their tissues of origin but also appear to influence the metabolism and function of tissues distal to their sites of expression. This may be secondary to metabolic changes in their primary tissues, and/or a result of FABP secretion from these tissues leading to effects on distal sites. Their levels in the circulation are increasingly explored as potential biomarkers for tissue-specific disease prognosis and progression. SUMMARY: The nine fatty acid-binding members of the FABP family have unique tissue-specific functions and important secondary effects on tissues in which they are not expressed. For many of the FABPs, circulating levels may be indicative of disease processes related to their primary tissues, and may influence physiological function in distal tissues.

Hepatorenal syndrome.

Hepatorenal syndrome (HRS) is a form of kidney function impairment that characteristically occurs in cirrhosis. Recent changes in terminology have led to acute HRS being referred to as acute kidney injury (AKI)-HRS and chronic HRS as chronic kidney disease (CKD)-HRS. AKI-HRS is characterized by a severe impairment of kidney function owing to vasoconstriction of the renal arteries in the absence of substantial abnormalities in kidney histology. Pathogenetic mechanisms involve disturbances in circulatory function due to a marked splanchnic arterial vasodilation, which triggers the activation of vasoconstrictor factors. An intense systemic inflammatory reaction that is characteristic of advanced cirrhosis may also be involved. The main triggering factors of AKI-HRS are bacterial infections, particularly spontaneous bacterial peritonitis. The diagnosis of AKI-HRS is a challenge because of a lack of specific diagnostic tools and mainly involves the differential diagnosis from other forms of AKI, particularly acute tubular necrosis. The prognosis of patients with AKI-HRS is poor, with a median survival of ≤3 months. The ideal treatment for AKI-HRS is liver transplantation in patients without contraindications. Medical therapy consists of vasoconstrictor drugs to counteract splanchnic arterial vasodilation together with volume expansion with albumin. Effective measures to prevent AKI-HRS include early identification and treatment of bacterial infections and the administration of albumin in patients with spontaneous bacterial peritonitis.

Prophylactic application of laser light restores L-FABP expression in the livers of rats submitted to partial ischemia.

OBJECTIVES: The objective of the present study was to evaluate the protective effect of pre-conditioning treatment with laser light on hepatic injury in rats submitted to partial ischemia using mitochondrial function and liver fatty acid binding protein as markers. METHODS: Rats were divided into four groups (n=5): 1) Control, 2) Control + Laser, 3) Partial Ischemia and 4) Partial Ischemia + Laser. Ischemia was induced by clamping the hepatic pedicle of the left and middle lobes of the liver for 60 minutes. Laser light at 660 nm was applied to the liver immediately prior to the induction of ischemia at 22.5 J/cm2, with 30 seconds of illumination at five individual points. The animals were sacrificed after 30 minutes of reperfusion. Blood and liver tissues were collected for analysis of mitochondrial function, determination of malondialdehyde and analysis of fatty acid binding protein expression by Western blot. RESULTS: Mitochondrial function decreased in the Partial Ischemia group, especially during adenosine diphosphate-activated respiration (state 3), and the expression of fatty acid binding protein was also reduced. The application of laser light prevented bioenergetic changes and restored the expression of fatty acid binding protein. CONCLUSION: Prophylactic application of laser light to the livers of rats submitted to partial ischemia was found to have a protective effect in the liver, with normalization of both mitochondrial function and fatty acid binding protein tissue expression.

First-stage palliation strategy for univentricular heart disease may impact risk for acute kidney injury.

OBJECTIVE: Norwood palliation for patients with single ventricle heart disease is associated with a significant risk for acute kidney injury, which portends a worse prognosis. We sought to investigate the impact of hybrid stage I palliation (Hybrid) on acute kidney injury risk. DESIGN: This study is a single-centre prospective case-control study of seven consecutive neonates with single ventricle undergoing Hybrid palliation. Levels of serum creatinine and four novel urinary biomarkers, namely neutrophil gelatinase-associated lipocalin, interleukin-18, liver fatty acid-binding protein, and kidney injury molecule-1, were obtained before and after palliation. Acute kidney injury was defined as a ⩾50% increase in serum creatinine within 48 hours after the procedure. Data were compared with a contemporary cohort of 12 neonates with single ventricle who underwent Norwood palliation. RESULTS: Patients who underwent Hybrid were more likely to be high-risk candidates (86 versus 25%, p=0.01) compared with those who underwent Norwood. Despite similar preoperative serum creatinine levels, there was a trend towards higher levels of postoperative peak serum creatinine (0.7 [0.63, 0.94] versus 0.56 [0.47, 0.74], p=0.06) and rate of acute kidney injury (67 versus 29%, p=0.17) in the Norwood cohort. Preoperative neutrophil gelatinase-associated lipocalin (58.4 [11, 86.3] versus 6.3 [5, 16.2], p=0.07) and interleukin-18 (30.6 [9.6, 167.2] versus 6.3 [6.3, 16.4], p=0.03) levels were higher in the Hybrid cohort. Nevertheless, longitudinal mixed-effect models demonstrated Hybrid palliation to be a protective factor against increased postoperative levels of neutrophil gelatinase-associated lipocalin (estimate -1.8 [-3.0, -9.0], p<0.001) and liver fatty acid-binding protein (-49.3 [-89.7, -8.8], p=0.018). CONCLUSIONS: In this single-centre case-control study, postoperative acute kidney injury risk did not differ significantly by single ventricle stage I treatment strategy; however, postoperative elevation in novel urinary biomarkers, consistent with subclinical kidney injury, was encountered in the Norwood cohort but not in the Hybrid cohort.

Prophylactic application of laser light restores L-FABP expression in the livers of rats submitted to partial ischemia

OBJECTIVES: The objective of the present study was to evaluate the protective effect of pre-conditioning treatment with laser light on hepatic injury in rats submitted to partial ischemia using mitochondrial function and liver fatty acid binding protein as markers. METHODS: Rats were divided into four groups (n=5): 1) Control, 2) Control + Laser, 3) Partial Ischemia and 4) Partial Ischemia + Laser. Ischemia was induced by clamping the hepatic pedicle of the left and middle lobes of the liver for 60 minutes. Laser light at 660 nm was applied to the liver immediately prior to the induction of ischemia at 22.5 J/cm2, with 30 seconds of illumination at five individual points. The animals were sacrificed after 30 minutes of reperfusion. Blood and liver tissues were collected for analysis of mitochondrial function, determination of malondialdehyde and analysis of fatty acid binding protein expression by Western blot. RESULTS: Mitochondrial function decreased in the Partial Ischemia group, especially during adenosine diphosphate-activated respiration (state 3), and the expression of fatty acid binding protein was also reduced. The application of laser light prevented bioenergetic changes and restored the expression of fatty acid binding protein. CONCLUSION: Prophylactic application of laser light to the livers of rats submitted to partial ischemia was found to have a protective effect in the liver, with normalization of both mitochondrial function and fatty acid binding protein tissue expression.

[Stable isotope labeling and parallel reaction monitoring-based proteomic quantification for biomarker screening and validation of hepatocellular carcinoma].

Liver cancer is the fifth most common cancer with extremely low five year survival rate. Early diagnosis is of great importance for cancer therapy. In this work, stable isotope labeling-based relative quantitative proteomics and parallel reaction monitoring-based target proteomics were combined for cancer biomarker screening and validation. By using this strategy, 70 significantly changed proteins in hepatocellular carcinoma tissues were obtained, among which seven proteins were further validated. The validated proteins contain the clinically used hepatocellular carcinoma (HCC) biomarker alpha-fetoprotein (AFP) and the reported biomarker candidates Heat shock protein HSP 90-beta (HSP90), fatty acid-binding protein, epidermal (FABP5) and alcohol dehydrogenase 4 (ADH4), which demonstrated the robustness of the strategy. The proteins identified in this work could be benefit for further HCC biomarker screening and clinical validation. Moreover, this strategy could be further applied to other cancer types.

Retinoic acid regulates cell-shape and -death of E-FABP (FABP5)-immunoreactive septoclasts in the growth plate cartilage of mice.

Septoclasts, which are mononuclear and spindle-shaped cells with many processes, have been considered to resorb the transverse septa of the growth plate (GP) cartilage at the chondro-osseous junction (COJ). We previously reported the expression of epidermal-type fatty acid-binding protein (E-FABP, FABP5) and localization of peroxisome proliferator-activated receptor (PPAR)ß/δ, which mediates the cell survival or proliferation, in septoclasts. On the other hand, retinoic acid (RA) can bind to E-FABP and is stored abundantly in the GP cartilage. From these information, it is possible to hypothesize that RA in the GP is incorporated into septoclasts during the cartilage resorption and regulates the growth and/or death of septoclasts. To clarify the mechanism of the cartilage resorption induced by RA, we administered an overdose of RA or its precursor vitamin A (VA)-deficient diet to young mice. In mice of both RA excess and VA deficiency, septoclasts decreased in the number and cell size in association with shorter and lesser processes than those in normal mice, suggesting a substantial suppression of resorption by septoclasts in the GP cartilage. Lack of PPARß/δ-expression, TUNEL reaction, RA receptor (RAR)ß, and cellular retinoic acid-binding protein (CRABP)-II were induced in E-FABP-positive septoclasts under RA excess, suggesting the growth arrest/cell-death of septoclasts, whereas cartilage-derived retinoic acid-sensitive protein (CD-RAP) inducing the cell growth arrest or morphological changes was induced in septoclasts under VA deficiency. These results support and do not conflict with our hypothesis, suggesting that endogenous RA in the GP is possibly incorporated in septoclasts and utilized to regulate the activity of septoclasts resorbing the GP cartilage.

Relation between postoperative ileus and anastomotic leakage after colorectal resection: a post hoc analysis of a prospective randomized controlled trial.

AIM: Anastomotic leakage (AL) following abdominal surgery is a critical determinant of postoperative recovery, of which the aetiology is largely unknown. Interestingly, interventions aimed at reducing the inflammatory response and postoperative ileus (POI) have an unexpected effect on AL. The aim of this study was to investigate the relation of POI with inflammation and AL after colorectal resection. METHOD: A post hoc analysis of a prospective randomized controlled trial in which patients underwent a colorectal resection was performed. Patients undergoing a colorectal resection were stratified into having or not having POI. The incidence of AL and other clinical parameters was registered prospectively. Intestinal fatty acid binding protein (I-FABP, a marker for tissue damage) and the inflammatory response in plasma and colon tissue were determined. RESULTS: AL was present in nine of 43 patients in the POI group, and in one of 65 in the group without POI (P < 0.001). There was a significant association between POI and AL (OR 12.57, 95% CI: 2.73-120.65; P = 0.0005). Patients with POI had significantly higher plasma levels of soluble tumour necrosis factor receptor 1 (TNFRSF1A) at 4 h postoperatively (0.89 ng/l, interquartile range 0.56) than patients without POI (0.80 ng/l, interquartile range 0.37; P = 0.04) and higher plasma levels of C-reactive protein on the second day postoperatively (234 ± 77 vs 163 ± 86 mg/l; P = 0.001). Patients who developed AL had significantly higher plasma levels of I-FABP compared with patients without AL at 24 h after onset of surgery. CONCLUSION: POI is associated with a higher prevalence of AL and an increased inflammatory response.

Acute Renal Failure - A Serious Complication in Patients After Kidney Transplantation.

Free radical-mediated injury releases proinflammatory cytokines and activates innate immunity. It has been suggested that the early innate response and the ischemic tissue damage play roles in the development of adaptive responses, which may lead to acute kidney rejection. Various durations of hypothermic kidney storage before transplantation add to ischemic tissue damage. The final stage of ischemic injury occurs during reperfusion that develops hours or days after the initial insult. Repair and regeneration processes occur together with cellular apoptosis, autophagy and necrosis and a favorable outcome is expected if regeneration prevails. Along the entire transplantation time course, there is a great demand for novel immune and nonimmune injury biomarkers. The use of these markers can be of great help in the monitoring of kidney injury in potential kidney donors, where acute kidney damage can be overlooked, in predicting acute transplant dysfunction during the early post-transplant periods, or in predicting chronic changes in long term followup. Numerous investigations have demonstrated that biomarkers that have the highest predictive value in acute kidney injury include NGAL, Cystatin C, KIM-1, IL-18, and L-FABP. Most investigations show that the ideal biomarker to fulfill all the needs in renal transplant has not been identified yet. Although, in many animal models, new biomarkers are emerging for predicting acute and chronic allograft damage, in human allograft analysis they are still not routinely accepted and renal biopsy still remains the gold standard.

Temporal profile of intestinal tissue expression of intestinal fatty acid-binding protein in a rat model of necrotizing enterocolitis

OBJECTIVES: Necrotizing enterocolitis is a severe multifactorial intestinal disorder that primarily affects preterm newborns, causing 20-40% mortality and morbidity. Intestinal fatty acid-binding protein has been reported to be a biomarker for the detection of intestinal injuries. Our aim was to assess intestinal tissue injury and the molecular expression of intestinal fatty acid-binding protein over time in a necrotizing enterocolitis model. METHODS: A total of 144 Newborn rats were divided into two groups: 1) Control, which received breastfeeding (n=72) and 2) Necrotizing Enterocolitis, which received formula feeding and underwent hypoxia and hypothermia (n=72). A total of six time points of ischemia (2 times a day for 3 days; 12 pups for each time point) were examined. Samples were collected for analysis of body weight, morphological and histological characteristics, intestinal weight, intestinal weight/body weight ratio, injury grade, and intestinal fatty acid-binding protein levels. RESULTS: Body and intestinal weights were lower in the Necrotizing Enterocolitis group than in the Control group (p<0.005 and p<0.0005, respectively). The intestinal weight/body weight ratio was higher in the Necrotizing Enterocolitis group than in the Control group (p<0.005) only at the sixth ischemia time point. The Necrotizing Enterocolitis group displayed higher expression of intestinal fatty acid-binding protein (p<0.0005) and showed greater tissue damage than the Control group. CONCLUSION: Intestinal fatty acid-binding protein was an efficient marker of ischemic injury to the intestine and a good correlation was demonstrated between the time of ischemic injury and the grade of intestinal injury.

Elevated expression of FABP3 and FABP4 cooperatively correlates with poor prognosis in non-small cell lung cancer (NSCLC).

Fatty acid binding proteins (FABPs) are intracellular lipid-binding proteins that are involved in a variety of biological cellular processes, including tumorigenesis. In this study, we explored the expression pattern of FABP3 and FABP4 in non-small cell lung cancer (NSCLC) as well as their roles in prognosis. We determined mRNA expression of FABP3 and FABP4 in matched pairs of cancerous and non-cancerous fresh frozen tissues from 30 NSCLC patients. Tissue microarray immunohistochemical analysis (TMA-IHC) was applied to determine the protein expression of FABP3 and FABP4 in 281 cancerous and 121 matched adjacent non-cancerous tissue samples. Our results showed that both mRNA and protein expression of FABP3 and FABP4 were significantly higher in cancerous tissues when compared to non-cancerous tissues. Furthermore, high expression of FABP3 or FABP4 in NSCLC was significantly associated with advanced tumor node metastasis (TNM) stage and had a negative impact on the overall survival of NSCLC patients. Concurrent high expression of FABP3 and FABP4 was significantly related to TNM stage. In conclusion, our research demonstrated that high FABP3 or FABP4 expression had strong prognostic value for overall survival in NSCLC. Detection of FABP3 and FABP4 cooperatively was helpful to predict the prognosis of NSCLC.

Mass spectrometric quantification of urinary human liver fatty acid binding protein in renal transplant recipients.

RATIONALE: Urinary liver fatty acid binding protein (L-FABP) has been evaluated as a promising early biomarker of renal ischemia in human kidney transplant patients. The use of L-FABP in clinical practice requires that this biomarker be associated with an analytical method that combines specificity, accuracy and robustness. This study aimed to evaluate an optimized multiple reaction monitoring (MRM) method using ultrafast liquid chromatography coupled with tandem mass spectrometry to measure urinary L-FABP levels in renal transplant recipients. METHODS: Purified recombinant human L-FABP tryptic standard was analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS/MS) and liquid chromatography (LC)/MS/MS to select for peptides that provided specificity and adequate response in developing an MRM method for urinary L-FABP quantification. Human urine samples collected from kidney transplant recipients were isolated, concentrated, precipitated and trypsin digested before mass spectrometric analysis of L-FABP. L-FABP levels were also measured in urine samples by enzyme immunoassay. RESULTS: The tryptic peptide ion MH(+) of (50) FTITAGSK(57) (m/z 824) provided an adequate signal and was used for quantification of L-FABP under conditions employed for LC/MS/MS analysis. MALDI-TOF-MS/MS spectra obtained by collision-induced dissociation of the parent MH(+) ion (50) FTITAGSK(57) resulted in a y3 product ion that was used for quantitative analysis by the MRM method. Urinary L-FABP content measured by both ELISA and LC/MS/MS after transplantation was significantly higher compared to before transplantation levels. The Spearman correlation coefficient between the two methods was statistically significant. Intra-day and inter-day coefficients of variation provided good repeatability and reproducibility for validation of LC/MS/MS analysis. CONCLUSIONS: LC/MS/MS quantification of L-FABP may provide a new reference method to determine changes in this potential biomarker in human kidney transplant patients.

Hepatocellular adenoma classification: a comparative evaluation of immunohistochemistry and targeted mutational analysis.

BACKGROUND: Four subtypes of hepatocellular adenomas (HCA) are recognized: hepatocyte-nuclear-factor-1α mutated (H-HCA), ß-catenin-mutated type with upregulation of glutamine synthetase (b-HCA), inflammatory type (IHCA) with serum-amyloid-A overexpression, and unclassified type. Subtyping may be useful since b-HCA appear to have higher risk of malignant transformation. We sought to apply subtype analysis and assess histological atypia, correlating these with next-generation sequencing analysis. METHODS: Twenty-six HCA were stained with serum amyloid A (SAA), liver fatty acid-binding protein (LFABP), glutamine synthetase (GS), and ß-catenin IHC, followed by analysis with a targeted multiplex sequencing panel. RESULTS: By IHC, 4 HCA (15.4 %) were classified as b-HCA, 11 (42.3 %) as IHCA, 9 (34.6 %) as H-HCA, and two (7.7 %) unclassifiable. Eight HCA (30.8 %) showed atypia (3 b-HCA, 4 IHCA and 1 H-HCA). Targeted sequencing confirmed HNF1A mutations in all H-HCA, confirming reliability of LFABP IHC in identifying these lesions. CTNNB1 mutations were detected in 1 of 4 (25 %) of GS/ß-catenin-positive cases, suggesting that positive GS stain does not always correlate with CTNNB1 mutations. CONCLUSIONS: Immunohistochemistry does not consistently identify b-HCA. Mutational analysis improves the diagnostic accuracy of ß-catenin-mutated HCA and is an important tool to assess risk of malignancy in HCA.

Hepatic adenomas with synchronous or metachronous fibrolamellar carcinomas: both are characterized by LFABP loss.

Rare hepatic adenomas are associated with synchronous or metachronous fibrolamellar carcinomas. The morphology of these adenomas has not been well described and they have not been subclassifed using the current molecular classification schema. We examined four hepatic adenomas co-occurring with or preceding a diagnosis of fibrolamellar carcinoma in three patients. On histological examination, three of the adenomas showed the typical morphology of HNF1-α inactivated adenomas, whereas one showed a myxoid adenoma morphology. All of the adenomas were negative for PRKACA rearrangements by Fluorescence in situ Hybridization (FISH) analysis. All four of the adenomas showed complete loss or significant reduction of liver fatty acid binding protein (LFABP) expression by immunohistochemistry. Interestingly, the fibrolamellar carcinomas in each case also showed loss of LFABP by immunohistochemistry. One of the fibrolamellar carcinomas was negative for PRKACA rearrangements by FISH, whereas the others were positive. To investigate if LFBAP loss is typical of fibrolamellar carcinomas in general, an additional cohort of tumors was studied (n=19). All 19 fibrolamellar carcinomas showed the expected PRKACA rearrangements and immunostains showed loss of LFABP in each case, consistent with HNF1-α inactivation. To validate this observation, mass spectrometry-based proteomics was performed on tumor-normal pairs of six fibrolamellar carcinomas and showed an average 10-fold reduction in LFABP protein levels, compared with matched normal liver tissue. In conclusion, hepatic adenomas co-occurring with fibrolamellar carcinomas show LFABP loss and are negative for PRKACA rearrangements, indicating they are genetically distinct lesions. These data also demonstrate that LFABP loss, which characterizes HNF1-α inactivation, is a consistent feature of fibrolamellar carcinoma, indicating HNF1-α inactivation is an important event in fibrolamellar carcinoma pathogenesis.