Enterocyte fatty acid-binding proteins (FABPs): different functions of liver and intestinal FABPs in the intestine

Uncovering the role of TREM-1 in celiac disease: In silico insights into the recognition of gluten-derived peptides and inflammatory mechanisms

BACKGROUND

Celiac disease (CD) is a chronic enteropathy characterized by a permanent intolerance to gluten. While CD has been associated with heightened T cell responses and the involvement of distinct innate immunity components, the role of the triggering receptor expressed on myeloid cells (TREM) family in this disease remains unclear. Thus, as TREM-1 has already been implicated in other inflammatory bowel diseases, and given its role in the amplification of inflammation, we hypothesized that it might play a role in the pathophysiology of CD.

METHODS AND RESULTS

the STRING tool was used to predict protein-protein interaction networks between TREM-1 and CD signaling pathways. Then, molecular docking and molecular dynamics simulations were conducted to explore potential interactions between TREM-1 and different peptides derived from alpha-gliadin (25-mer, 33-mer and p31-43). Finally, we used transcriptomic data, available from public repositories, to assess TREM1 gene expression, and genes involved in its signaling pathway, in CD patients. Our results found an association between TREM-1 and CD markers, with STRING analysis, and the in silico simulations suggesting that the receptor might recognize the alpha-gliadin peptides, with the TREM-1/p31-43 interaction as the most likely interaction to occur biologically. Furthermore, TREM1 and its signaling pathway were increased in patients with active CD, while in those in clinical remission, the expression levels were similar to healthy controls.

CONCLUSIONS

collectively, our findings suggest that TREM-1 might recognize alpha-gliadin derived peptides, and TREM-1's activation may contribute to the intestinal inflammation observed in CD.

Establishing the Role of Liver Fatty Acid-Binding Protein in Post-Golgi Very-Low-Density Lipoprotein Trafficking Using a Novel Fluorescence-Based Assay

The liver plays a crucial role in maintaining lipid homeostasis by converting toxic free fatty acids into VLDL, which the body uses for energy. Even minor changes in VLDL formation and secretion can result in serious health conditions such as atherosclerosis and non-alcoholic fatty liver disease. Despite the importance of VLDL, the proteins and signaling pathways involved in its regulation remain largely unknown. This study aims to develop a novel methodology to study intracellular VLDL transport events and explore the role of liver fatty acid-binding protein (LFABP) in VLDL transport and secretion. Current methods to study VLDL are often tedious, time-consuming, and expensive, underscoring the need for an alternative approach. We designed a new immunofluorescence-based assay to track the formation and secretion of VLDL in cells over time using fluorescently tagged TopFluor oleic acid. Confocal microscopy confirmed that TopFluor oleic acid enters hepatocytes and colocalizes with the ER, Golgi, and plasma membrane. Additionally, the collection of cell culture media revealed that TopFluor was incorporated into VLDL particles, as confirmed by fluorescence readings and ApoB100 immunoblots. This novel assay provides a valuable tool for further research into the mechanisms of VLDL regulation and the development of potential therapeutic targets for related diseases. Utilizing this assay, we identified LFABP as a key regulatory protein in post-Golgi VLDL trafficking. Our data suggest that LFABP plays a crucial role in this process, and its functional impairment leads to reduced VLDL secretion.

Impaired intestinal permeability in patients with multiple sclerosis

BACKGROUND

A number of recent studies have shown that the intestinal microbiome, part of the brain-gut axis, is implicated in the pathophysiology of multiple sclerosis. An essential part of this axis, is the intestinal barrier and gastrointestinal disorders with intestinal barrier dysregulation appear to be linked to CNS demyelination, and hence involved in the etiopathogenesis of multiple sclerosis (MS).

OBJECTIVE

The aim of this study was to evaluate the integrity of the intestinal barrier in patients with clinically definite multiple sclerosis (CDMS) and clinically isolated syndrome (CIS) using two serum biomarkers, claudin-3 (CLDN3), a component of tight epithelial junctions, and intestinal fatty acid binding protein (I-FABP), a cytosolic protein in enterocytes.

METHODS

Serum levels of CLDN3 in 37 MS patients and 22 controls, and serum levels of I-FABP in 46 MS patients and 51 controls were measured using commercial ELISA kits. Complete laboratory tests excluded the presence of gluten-related disorders in all subjects. Thirty MS patients received either disease-modifying drugs (DMD), immunosuppression (IS) or corticosteroid treatment.

RESULTS

CLDN3 levels were only significantly higher in the MS patients treated with DMD or IS compared to the control group (P=0.006). There were no differences in I-FABP serum levels between the groups. Serum CLDN3 levels did not correlate with serum I-FABP levels in CDMS, in CIS patients or controls.

CONCLUSIONS

In multiple sclerosis patients, the intestinal epithelium may be impaired with increased permeability, but without significant enterocyte damage characterized by intracellular protein leakage. Based on our data, CLDN3 serum levels appear to assess intestinal dysfunction in MS patients but mainly in treated ones.

Transport functions of intestinal lymphatic vessels

Lymphatic vessels are crucial for fluid absorption and the transport of peripheral immune cells to lymph nodes. However, in the small intestine, the lymphatic fluid is rich in diet-derived lipids incorporated into chylomicrons and gut-specific immune cells. Thus, intestinal lymphatic vessels have evolved to handle these unique cargoes and are critical for systemic dietary lipid delivery and metabolism. This Review covers mechanisms of lipid absorption from epithelial cells to the lymphatics as well as unique features of the gut microenvironment that affect these functions. Moreover, we discuss details of the intestinal lymphatics in gut immune cell trafficking and insights into the role of inter-organ communication. Lastly, we highlight the particularities of fat absorption that can be harnessed for efficient lipid-soluble drug distribution for novel therapies, including the ability of chylomicron-associated drugs to bypass first-pass liver metabolism for systemic delivery. In all, this Review will help to promote an understanding of intestinal lymphatic-systemic interactions to guide future research directions.

Hypothyroidism impairs the circadian rhythmicity of clock genes and proteins involved in gut nutrient absorption in female mice

Hypothyroidism is a common thyroid dysfunction with a higher prevalence in women. Impairments in the regulation of basal metabolism, small intestine nutrient transporter, dyslipidemia, and disruption in circadian clocks have been associated with the thyroid disorder. This study aimed to evaluate whether hypothyroidism affects the small intestine circadian clock and the daily expression pattern of gut nutrient transporters in female mice. Adult female C57BL/6J mice were subjected to hypothyroidism by the administration of methimazole (0.1%) and sodium perchlorate (1%) in drinking water for 45 days. After, the animals were subdivided and euthanized every 4 h over the 24 h period under deep anesthesia. The proximal small intestine segment was collected and immediately frozen for gene expression analysis of circadian core clock components (Bmal1, Per2, Cry1, and Nr1d1) and nutrient transporters by RT-qPCR. The daily protein content of nutrient transporters involved in the absorption of the products of hydrolysis of lipids, proteins, and carbohydrates was evaluated over 24 h in isolated small intestinal epithelium by Western blotting. The expression of clock genes and protein content of nutrients transporters in the jejunum of control female mice exhibited a well-defined circadian rhythmicity, while no rhythmic oscillation over 24 h was observed for the transporter transcripts. Hypothyroidism abolished the circadian rhythmicity of circadian clock, punctually reduced the transcript content of Slc2a5 (GLUT5) at ZT12 and Slc2a2 (GLUT2) at ZT4, and disrupted the circadian oscillation of L-FABP, CD36, PEPT1, and GLUT2 protein contents in the small intestine of female mice. In conclusion, our findings indicate that thyroid hormones modulate the circadian clock of small intestine and the daily rhythmicity of components related to absorptive processes in female mice. Moreover, our data suggest that the mechanisms triggered by thyroid hormones involve posttranscriptional and/or translational modifications of proteins related to lipid, protein, and carbohydrate absorption. Together, these data contribute to the general comprehension of metabolic alterations often observed in hypothyroidism and have far-reaching implications at clinical levels considering the higher worldwide prevalence of hypothyroidism in women and its association with obesity and metabolic syndrome.

A data mining approach to identify key radioresponsive genes in mouse model of radiation-induced intestinal injury

BACKGROUND

Radiation-mediated GI injury (RIGI) is observed in humans either due to accidental or intentional exposures. This can only be managed with supporting care and no approved countermeasures are available till now. Early detection and monitoring of RIGI is important for effective medical management and improve survival chances of exposed individuals.

OBJECTIVE

The present study aims to identify new signatures of RIGI using data mining approach followed by validation of selected hub genes in mice.

METHODS

Data mining study was performed using microarray datasets from Gene Expression Omnibus database. The differentially expressed genes were identified and further validated in total-body irradiated mice.

RESULTS

Based on KEGG pathway analysis, lipid metabolism was found as one of the predominant pathways altered in irradiated intestine. Extensive alteration in lipid profile and lipid modification was observed in this tissue. A protein-protein interaction network revealed top 08 hub genes related to lipid metabolism, namely Fabp1, Fabp2, Fabp6, Npc1l1, Ppar-α, Abcg8, Hnf-4α, and Insig1. qRT-PCR analysis revealed significant up-regulation of Fabp6 and Hnf-4α and down-regulation of Fabp1, Fabp2 and Insig1 transcripts in irradiated intestine. Radiation dose and time kinetics study revealed that the selected 05 genes were altered differentially in response to radiation in intestine.

CONCLUSION

Finding suggests that lipid metabolism is one of the key targets of radiation and its mediators may act as biomarkers in detection and progression of RIGI.

TPTEP1 impedes the reprogramming of fatty acid metabolism in triple negative breast cancer via miR-1343-3p/SIRT3 axis

Recently, the important role of fatty acid (FA) metabolism in cancers has been highlighted. Sirtuin 3 (SIRT3) is determined as an important regulator in the FA metabolism of cancer cells. We are going to verify whether and how lncRNA transmembrane phosphatase with tensin homology pseudogene 1 (TPTEP1) and SIRT3 may exert certain impact on the FA metabolism in triple-negative breast cancer (TNBC). Firstly, TPTEP1 was verified to be with low expression in TNBC cells. Moreover, down-regulation of TPTEP1 was caused by YY1 transcription factor. Functional assays determined the effects of TPTEP1 on the process of TNBC. The results disclosed that TPTEP1 up-regulation significantly repressed cell proliferation, migration, invasion, EMT and the reprogramming of FA metabolism in TNBC. Mechanism experiments detected the regulatory mechanism between TPTEP1 and SIRT3, which turned out that TPTEP1 positively regulated SIRT3 to affect FOXO3a and inhibit the Wnt/β-catenin pathway via sponging miR-1343-3p. All in all, TPTEP1 functioned as a tumor suppressor to regulate TNBC progression via the miR-1343-3p/SIRT3/FOXO3a/Wnt/β-catenin signaling.

Lysophospholipid Supplementation in Broiler Breeders' Diet Benefits Offspring's Productive Performance, Blood Parameters, and Hepatic β-Oxidation Genes

The present study aimed to investigate whether supplementation of modified lysophospholipids (LPLs) in the diet of broiler breeders can benefit their offspring. A total of 264 49-week-old breeders (Ross 308) were allocated and fed based on a 2 × 2 factorial arrangement with two levels of dietary energy (normal energy = 2800 kcal/kg and low energy = 2760 kcal/kg) and two LPL levels (0 and 0.5 g/kg) for periods of 8 and 12 weeks. The offspring were assessed for growth performance, serum parameters, hepatic antioxidative capability, and expression of genes involved in liver β-oxidation at 7 days old. The LPL inclusion improved (p < 0.01) average body weight (ABW), average daily gain (ADG), and feed conversion ratio (FCR). The offspring of 61-week-old breeders fed with LPL exhibited reduced serum triglyceride levels (p < 0.01) but an increase in hepatic glutathione peroxidase (p < 0.05). The LPL increased (p < 0.001) the mRNA expression of the PGC-1α gene in the liver. Supplementing LPL in low-energy diets resulted in higher FABP1 gene expression (p < 0.05) in the intestine. In conclusion, LPL supplementation in the breeders' diet improved offspring performance by enhancing fatty acid absorption, hepatic indices, and the expression of genes involved in liver β-oxidation.

Elevated intestinal fatty acid-binding protein levels as a marker of portal hypertension and gastroesophageal varices in cirrhosis

We measured intestinal fatty acid-binding protein (I-FABP) levels, a useful marker of small intestinal mucosal injury, in patients with cirrhosis to determine their relationship with liver function and complications. This cross-sectional study included 71 patients with cirrhosis admitted for treatment of cirrhotic complications or hepatocellular carcinoma (cohort A) and 104 patients with cirrhosis who received direct-acting antiviral therapy for HCV (cohort B). I-FABP levels, measured by ELISA, were evaluated relative to hepatic reserve and compared with non-invasive scoring systems for diagnostic performance in cirrhotic complications. The median I-FABP level in both cohorts were significantly elevated in patients with reduced hepatic reserve (CTP grade A/BC cohort A, 2.33/3.17 ng/mL, p = 0.032; cohort B, 2.46/3.64 ng/mL, p = 0.008) and complications with gastroesophageal varices (GEV; GEV (-)/(+) cohort A, 1.66/3.67 ng/mL, p < 0.001; cohort B, 2.32/3.36 ng/mL; p = 0.003). Further, multiple logistic regression analysis identified I-FABP as the only factor contributing to GEV presence in both cohorts, which outperformed non-invasive scoring systems for GEV diagnosis (sensitivity 84.6%; specificity 84.2%; sensitivity 69.6%; specificity 63.8%, respectively). In conclusion, elevated small-intestinal mucosal injury in patients with cirrhosis was related to reduced hepatic reserve and GEV presence. I-FABP levels reflect portal hypertension and may be useful in cirrhosis management.

Intestinal Lymphatic Biology, Drug Delivery, and Therapeutics: Current Status and Future Directions

Historically, the intestinal lymphatics were considered passive conduits for fluids, immune cells, dietary lipids, lipid soluble vitamins, and lipophilic drugs. Studies of intestinal lymphatic drug delivery in the late 20th century focused primarily on the drugs' physicochemical properties, especially high lipophilicity, that resulted in intestinal lymphatic transport. More recent discoveries have changed our traditional view by demonstrating that the lymphatics are active, plastic, and tissue-specific players in a range of biological and pathological processes, including within the intestine. These findings have, in turn, inspired exploration of lymph-specific therapies for a range of diseases, as well as the development of more sophisticated strategies to actively deliver drugs or vaccines to the intestinal lymph, including a range of nanotechnologies, lipid prodrugs, and lipid-conjugated materials that "hitchhike" onto lymphatic transport pathways. With the increasing development of novel therapeutics such as biologics, there has been interest in whether these therapeutics are absorbed and transported through intestinal lymph after oral administration. Here we review the current state of understanding of the anatomy and physiology of the gastrointestinal lymphatic system in health and disease, with a focus on aspects relevant to drug delivery. We summarize the current state-of-the-art approaches to deliver drugs and quantify their uptake into the intestinal lymphatic system. Finally, and excitingly, we discuss recent examples of significant pharmacokinetic and therapeutic benefits achieved via intestinal lymphatic drug delivery. We also propose approaches to advance the development and clinical application of intestinal lymphatic delivery strategies in the future. SIGNIFICANCE STATEMENT: This comprehensive review details the understanding of the anatomy and physiology of the intestinal lymphatic system in health and disease, with a focus on aspects relevant to drug delivery. It highlights current state-of-the-art approaches to deliver drugs to the intestinal lymphatics and the shift toward the use of these strategies to achieve pharmacokinetic and therapeutic benefits for patients.

Long-term arsenic exposure decreases mice body weight and liver lipid droplets

Arsenic (As) is a widespread global pollutant, and there is significant controversy surrounding its complex relationship with obesity, primarily focused on short-term exposure. Recognizing the prolonged nature of dietary arsenic exposure, this study involved feeding mice with arsenic-contained food for 14 months. The results showed that mice exposed to arsenic developed a non-alcoholic fatty liver condition, characterized by a light-yellow hue on the liver surface and various pathological alterations in the liver cells, including enlarged nuclei, cellular necrosis, inflammatory infiltration, dysfunctional mitochondria, and endoplasmic reticulum disorganization. There were also disruptions in biochemistry indices, with a significant increase in total cholesterol (TC) level and a decrease in high-density lipoprotein (HDL) level. However, some contradictory observations occurred, such as a significant decrease in body weight, triglyceride (TG) level, and the numbers of lipid droplets. Several genes related to lipid metabolism were tested, and a model was used to explain these discrepancies. Besides, examinations of the colon revealed compromised intestinal barrier function and signs of inflammation. Fecal 16S rRNA sequencing and pseudo-targeted metabolomics revealed disruptions in internal homeostasis, such as modules, nodes, connections, and lipid-related KEGG pathways. Fecal targeted metabolomics analyses of short-chain fatty acids (SCFAs) and bile acids (BAs) demonstrated a significant upregulation in three primary bile acids (CA, CDCA, TCDCA), four secondary bile acids (TUDCA, DCA, LCA, GUDCA), and total SCFAs level. Oxidative stress and inflammation were also evident. Additionally, based on correlation analysis and mediation analysis, it was assumed that changes in the microbiota (e.g., Dubosiella) can impact the liver metabolites (e.g., TGs) through alterations in fecal metabolites (e.g., LPCs). These findings provide a theoretical reference for the long-term effect of arsenic exposure on liver lipid metabolism.

TNFSF13 insufficiency disrupts human colonic epithelial cell-mediated B cell differentiation

Cytokines mediating epithelial and immune cell interactions modulate mucosal healing- a process that goes awry with chronic inflammation as in inflammatory bowel disease. TNFSF13 is a cytokine important for B cell maturation and function, but roles for epithelial TNFSF13 and putative contribution to inflammatory bowel disease are poorly understood. We evaluated functional consequences of a novel monoallelic TNFSF13 variant using biopsies, tissue-derived colonoids and induced pluripotent stem cell (iPSC)-derived colon organoids. TNFSF13 variant colonoids exhibited a >50% reduction in secreted TNFSF13, increased epithelial proliferation, and reduced apoptosis, which was confirmed in iPSC-derived colon organoids. Single cell RNA-sequencing, flow cytometry, and co-immunoprecipitation identified FAS as the predominant colonic epithelial receptor for TNFSF13. Imaging mass cytometry revealed an increase in epithelial-associated B cells in TNFSF13 variant colon tissue sections. Finally, TNFSF13 variant colonoids co-cultured with memory B cells demonstrated a reduction in the production of IgA+ plasma cells compared to control colonoid co-cultures. Our findings support a role for epithelial TNFSF13 as a regulator of colonic epithelial growth and epithelial crosstalk with B cells.

Serum markers of microbial translocation and intestinal damage in assessment of gastrointestinal tract involvement in systemic sclerosis

Gastrointestinal (GI) tract involvement affects up to 90% of Systemic sclerosis (SSc) patients. The presence of GI symptoms is assessed by the University of California, Los Angeles, and Scleroderma Clinical Trials Consortium Gastrointestinal Scale (UCLA SCTC GIT 2.0). Microbial translocation (MT) is reported in SSc patients consequently to increased intestinal permeability due to intestinal damage (ID) and dysbiosis. Aim of this study was to assess circulating levels of LBP and EndoCab IgM (markers of MT), IL-6 (marker of inflammation), I-FABP and Zonulin (markers of ID) in a cohort of SSc patients and healthy controls (HC). Moreover, we aimed to correlate these parameters with severity of GI symptoms. UCLA SCTC GIT 2.0 questionnaire was administered to 60 consecutive SSc patients. Markers of MT, inflammation and ID were evaluated in SSc patients and HC. SSc patients had higher median value of markers of MT, inflammation and ID than HC. The logistic regression analysis showed LBP as the only variable associated with an UCLA total score "moderate-to-very severe" [OR 1.001 (CI 95%: 1.001-1.002), p < 0.001]. The logistic regression analysis showed LBP [OR 1.002 (CI 95%: 1.001-1.003), p < 0.01] and disease duration [OR 1.242 (CI 95%: 1.023-1.506), p < 0.05] as variables associated with UCLA distension/bloating "moderate-to-very severe". The logistic regression analysis showed LBP as the only variable associated with UCLA diarrhea "moderate-to-very severe" [OR 1.002 (CI 95%: 1.001-1.003), p < 0.01]. SSc patients with dysregulation gut mucosal integrity expressed by high levels of MT and ID biomarkers had more severe GI symptoms.

Plasma proteomics and lipidomics facilitate elucidation of the link between Alzheimer's disease development and vessel wall fragility

Proximity Extension Assay (PEA) and mass spectrometry (MS) methodologies were utilized for the proteomic and lipidomic characterization of plasma specimens from patients who developed Alzheimer's disease. Proteomics was performed by both PEA and Liquid Chromatography (LC)/MS in this study, but all the more because LC/MS generally tends to be biased towards proteins with high expression and high variability, generating hypotheses proved challenging. Consequently, attempt was made to interpret the results from the PEA data. There were 150 significantly variable proteins and 68 lipids among 1000 proteins and 400 lipids. Pathway analysis was performed for both total and variable proteins measured to reduce bias, and it appeared that vascular fragility was related to AD. Furthermore, a multitude of lipid-associated proteins exhibited statistical changes. In certain instances, the function of individual proteins affected the factors associated with them, whereas others demonstrated trends contrary to anticipated outcomes. These trends seem indicative of diverse feedback mechanisms that provide homeostatic equilibrium. The degree of unsaturation of fatty acids, correlated with cardiovascular risk, warrants specific attention. Certain bile acids exhibited the potential to cause vascular endothelial damage. Contemplating these discoveries in tandem with previously documented phenomena, subtle shifts in homeostatic functions seem to be linked to the fragility of vascular endothelial cells. This is evidenced by the slow and chronic evolution of Alzheimer's disease from preclinical stages to its manifestation.

Transcriptome, histology, and enzyme activities analysis of liver in Phoxinus lagowskii to the low temperature stress and recovery

Assessing the response and resilience of fish to low temperatures over different time scales can provide valuable insights into their mechanisms of adaptation to cold conditions. Farmed Amur minnows (Phoxinus lagowskii) frequently encounter low temperatures, especially during winter. However, the specific responses of P. lagowskii to low-temperature stress remain largely unexplored. In this study, we examined serum glucose and cortisol levels, histological changes, enzymes associated with phosphate and carbohydrate metabolism, triglyceride levels, and liver transcriptomics under various conditions: control (CK), short-term cold exposure (6 days, SC), prolonged cold exposure (14 days, PC), and recovery (RY) from cold exposure at 2 °C. Liver vacuolation was observed during short-term cold exposure. Additionally, we analyzed the enzymatic activity related to carbohydrate and lipid metabolism in serum and liver. Liver transcriptomic data revealed that the PPAR signaling pathway and autophagy-related genes were enriched during short-term cold exposure. Carbohydrate metabolism-related pathways, including the AMPK and MAPK signaling pathways, were significantly enriched after prolonged cold exposure. Metabolic pathways such as fat digestion and absorption, glycine, serine, and threonine metabolism, and arginine and proline metabolism were significantly enriched in the recovery group. Rapid warming after prolonged cold stress allowed P. lagowskii to recover quickly. These findings suggest that P. lagowskii has a strong adaptive capacity for energy metabolism during prolonged cold exposure and the ability to recover rapidly from cold stress. A comprehensive examination of the histological, physiological, biochemical, and molecular responses of P. lagowskii to low temperatures is crucial for developing effective strategies for cultivating this species in challenging environments.

Fatty Acid-Binding Protein 4-Mediated Regulation Is Pivotally Involved in Retinal Pathophysiology: A Review

Fatty acid-binding proteins (FABPs), a family of lipid chaperone molecules that are involved in intracellular lipid transportation to specific cellular compartments, stimulate lipid-associated responses such as biological signaling, membrane synthesis, transcriptional regulation, and lipid synthesis. Previous studies have shown that FABP4, a member of this family of proteins that are expressed in adipocytes and macrophages, plays pivotal roles in the pathogenesis of various cardiovascular and metabolic diseases, including diabetes mellitus (DM) and hypertension (HT). Since significant increases in the serum levels of FABP4 were detected in those patients, FABP4 has been identified as a crucial biomarker for these systemic diseases. In addition, in the field of ophthalmology, our group found that intraocular levels of FABP4 (ioFABP4) and free fatty acids (ioFFA) were substantially elevated in patients with retinal vascular diseases (RVDs) including proliferative diabetic retinopathy (PDR) and retinal vein occlusion (RVO), for which DM and HT are also recognized as significant risk factors. Recent studies have also revealed that ioFABP4 plays important roles in both retinal physiology and pathogenesis, and the results of these studies have suggested potential molecular targets for retinal diseases that might lead to future new therapeutic strategies.

Transcriptome analysis revealed potential mechanisms of channel catfish growth advantage over blue catfish in a tank culture environment

Channel catfish (Ictalurus punctatus) and blue catfish (Ictalurus furcatus) are two economically important freshwater aquaculture species in the United States, with channel catfish contributing to nearly half of the country's aquaculture production. While differences in economic traits such as growth rate and disease resistance have been noted, the extent of transcriptomic variance across various tissues between these species remains largely unexplored. The hybridization of female channel catfish with male blue catfish has led to the development of superior hybrid catfish breeds that exhibit enhanced growth rates and improved disease resistance, which dominate more than half of the total US catfish production. While hybrid catfish have significant growth advantages in earthen ponds, channel catfish were reported to grow faster in tank culture environments. In this study, we confirmed channel fish's superiority in growth over blue catfish in 60-L tanks at 10.8 months of age (30.3 g and 11.6 g in this study, respectively; p < 0.001). In addition, we conducted RNA sequencing experiments and established transcriptomic resources for the heart, liver, intestine, mucus, and muscle of both species. The number of expressed genes varied across tissues, ranging from 5,036 in the muscle to over 20,000 in the mucus. Gene Ontology analysis has revealed the functional specificity of differentially expressed genes within their respective tissues, with significant pathway enrichment in metabolic pathways, immune activity, and stress responses. Noteworthy tissue-specific marker genes, including lrrc10, fabp2, myog, pth1a, hspa9, cyp21a2, agt, and ngtb, have been identified. This transcriptome resource is poised to support future investigations into the molecular mechanisms underlying environment-dependent heterosis and advance genetic breeding efforts of hybrid catfish.

Characterisation of biomarkers of intestinal barrier function in response to a high fat/high carbohydrate meal and corticotropin releasing hormone

BACKGROUND

Variation of circulating concentrations of putative biomarkers of intestinal barrier function over the day and after acute physiological interventions are poorly documented on humans. This study aimed to examine the stability and pharmacokinetics of changes in plasma concentrations of intestinal Fatty-acid -binding -protein (IFABP), Lipopolysaccharide-binging-protein (LBP), soluble CD14, and Syndecan-1 after acute stress and high fat-high-carbohydrate meal.

METHODS

In a single-blinded, cross-over, randomised study, healthy volunteers received on separate days corticotropin-releasing hormone (CRH, 100 μg) or normal saline (as placebo) intravenously in random order, then a HFHC meal. Participants were allowed low caloric food. Markers of intestinal barrier function were measured at set timed intervals from 30 minutes before to 24 hours after interventions.

RESULTS

10 participants (50% female) completed all three arms of the study. IFABP decreased by median 3.6 (IQR 1.4-10)% from -30 minutes to zero time (p = 0.001) and further reduced by 25 (20-52)% at 24 hours (p = 0.01) on the low caloric diet, but did not change in response to the meal. Syndecan-1, LBP and sCD14 were stable over a 24-hour period and not affected acutely by food intake. LBP levels 2 hours after CRH reduced by 0.61 (-0.95 to 0.05) μg/ml compared with 0.16 (-0.3 to 0.5) μg/ml post placebo injection (p = 0.05), but other markers did not change.

CONCLUSION

Concentrations of IFABP, but not other markers, are unstable over 24 hours and should be measured fasting. A HFHC meal does not change intestinal permeability. Transient reduction of LPB after CRH confirms acute barrier dysfunction during stress.

A Mixture of Formic Acid, Benzoic Acid, and Essential Oils Enhanced Growth Performance via Modulating Nutrient Uptake, Mitochondrion Metabolism, and Immunomodulation in Weaned Piglets

This study aimed to evaluate the effects of a complex comprising formic acid, benzoic acid, and essential oils (AO3) on the growth performance of weaned piglets and explore the underlying mechanism. Dietary AO3 supplementation significantly enhanced the average daily gain (ADG) and average daily feed intake (ADFI), while decreasing the feed conversion rate (FCR) and diarrhea rate (p < 0.05). Additionally, AO3 addition altered the fecal microflora composition with increased abundance of f_Prevotellaceae. LPS challenges were further conducted to investigate the detailed mechanism underlying the benefits of AO3 supplementation. The piglets fed with AO3 exhibited a significant increase in villus height and decrease in crypt depth within the jejunum, along with upregulation of ZO-1, occludin, and claudin-1 (p < 0.05) compared with those piglets subjected to LPS. Furthermore, AO3 supplementation significantly ameliorated redox disturbances (T-AOC, SOD, and GSH) and inflammation (TNF-α, IL-1β, IL-6, and IL-12) in both the serum and jejunum of piglets induced by LPS, accompanied by suppressed activation of the MAPK signaling pathway (ERK, JNK, P38) and NF-κB. The LPS challenge downregulated the activation of the AMPK signaling pathway, mRNA levels of electron transport chain complexes, and key enzymes involved in ATP synthesis, which were significantly restored by the AO3 supplementation. Additionally, AO3 supplementation restored the reduced transport of amino acids, glucose, and fatty acids induced by LPS back to the levels observed in the control group. In conclusion, dietary AO3 supplementation positively affected growth performance and gut microbiota composition, also enhancing intestinal barrier integrity, nutrient uptake, and energy metabolism, as well as alleviating oxidative stress and inflammation under LPS stimulation.

The Checkpoints of Intestinal Fat Absorption in Obesity

In this chapter, intestinal lipid transport, which plays a central role in fat homeostasis and the development of obesity in addition to the mechanisms of fatty acids and monoacylglycerol absorption in the intestinal lumen and reassembly of these within the enterocyte was described. A part of the resynthesized triglycerides (triacylglycerols; TAG) is repackaged in the intestine to form the hydrophobic core of chylomicrons (CMs). These are delivered as metabolic fuels, essential fatty acids, and other lipid-soluble nutrients, from enterocytes to the peripheral tissues following detachment from the endoplasmic reticulum membrane. Moreover, the attitudes of multiple receptor functions in dietary lipid uptake, synthesis, and transport are highlighted. Additionally, intestinal fatty acid binding proteins (FABPs), which increase the cytosolic flux of fatty acids via intermembrane transfer in enterocytes, and the functions of checkpoints for receptor-mediated fatty acid signaling are debated. The importance of the balance between storage and secretion of dietary fat by enterocytes in determining the physiological fate of dietary fat, including regulation of blood lipid concentrations and energy balance, is mentioned. Consequently, promising checkpoints regarding how intestinal fat processing affects lipid homeostatic mechanisms and lipid stores in the body and the prevention of obesity-lipotoxicity due to excessive intestinal lipid absorption are evaluated. In this context, dietary TAG digestion, pharmacological inhibition of TAG hydrolysis, the regulation of long-chain fatty acid uptake traffic into adipocytes, intracellular TAG resynthesis, the enlargement of cytoplasmic lipid droplets in enterocytes and constitutional alteration of their proteome, CD36-mediated conversion of diet-derived fatty acid into cellular lipid messengers and their functions are discussed.

Diagnostic and Prognostic Value of IL-10, FABP2 and LPS Levels in HCC Patients

Hepatocellular carcinoma (HCC) still lacks valuable diagnostic and prognostic tools. This study aimed to investigate the potential diagnostic and prognostic value of baseline interleukin (IL)-10, fatty acid-binding protein 2 (FABP2) and lipopolysaccharide (LPS) levels in patients with HCC. Serum levels of IL-10, FABP2 and LPS in 47 newly diagnosed HCC patients and 50 healthy individuals were estimated and compared. The best cut-off points for baseline IL-10, FABP2 and LPS levels predicting overall survival (OS) were evaluated. Both levels of FABP2 and IL-10 were significantly higher in HCC patients vs. control group (median 2095 vs. 1772 pg/mL, p = 0.026; 9.94 vs. 4.89 pg/mL, p < 0.001) and may serve as potential biomarkers in complex HCC diagnostic tools. The cut-off value of 2479 pg/mL for FABP2 was determined to have the highest sensitivity (66.7%) and specificity (55.6%) to distinguish patients with a median OS longer than 17 months. However, the median OS of patients with high and low levels of FABP2 were not significantly different (p = 0.896). The prognostic value of LPS as well as FABP2 and IL-10 for HCC patients appears to be limited.

Fatty-Acid-Binding Proteins: From Lipid Transporters to Disease Biomarkers

Fatty-acid-binding proteins (FABPs) serve a crucial role in the metabolism and transport of fatty acids and other hydrophobic ligands as an intracellular protein family. They are also recognized as a critical mediator in the inflammatory and ischemic pathways. FABPs are found in a wide range of tissues and organs, allowing them to contribute to various disease/injury developments that have not been widely discussed. We have collected and analyzed research journals that have investigated the role of FABPs in various diseases. Through this review, we discuss the findings on the potential of FABPs as biomarkers for various diseases in different tissues and organs, looking at their expression levels and their roles in related diseases according to available literature data. FABPs have been reported to show significantly increased expression levels in various tissues and organs associated with metabolic and inflammatory diseases. Therefore, FABPs are a promising novel biomarker that needs further development to optimize disease diagnosis and prognosis methods along with previously discovered markers.

Whole-Transcriptome RNA Sequencing Uncovers the Global Expression Changes and RNA Regulatory Networks in Duck Embryonic Myogenesis

Duck meat is pivotal in providing high-quality protein for human nutrition, underscoring the importance of studying duck myogenesis. The regulatory mechanisms governing duck myogenesis involve both coding and non-coding RNAs, yet their specific expression patterns and molecular mechanisms remain elusive. To address this knowledge gap, we performed expression profiling analyses of mRNAs, lncRNAs, circRNAs, and miRNAs involved in duck myogenesis using whole-transcriptome RNA-seq. Our analysis identified 1733 differentially expressed (DE)-mRNAs, 1116 DE-lncRNAs, 54 DE-circRNAs, and 174 DE-miRNAs when comparing myoblasts and myotubes. A GO analysis highlighted the enrichment of DE molecules in the extracellular region, protein binding, and exocyst. A KEGG analysis pinpointed pathways related to ferroptosis, PPAR signaling, nitrogen metabolism, cell cycle, cardiac muscle contraction, glycerolipid metabolism, and actin cytoskeleton. A total of 51 trans-acting lncRNAs, including ENSAPLT00020002101 and ENSAPLT00020012069, were predicted to participate in regulating myoblast proliferation and differentiation. Based on the ceRNAs, we constructed lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA ceRNA networks involving five miRNAs (miR-129-5p, miR-133a-5p, miR-22-3p, miR-27b-3p, and let-7b-5p) that are relevant to myogenesis. Furthermore, the GO and KEGG analyses of the DE-mRNAs within the ceRNA network underscored the significant enrichment of the glycerolipid metabolism pathway. We identified five different DE-mRNAs, specifically ENSAPLG00020001677, ENSAPLG00020002183, ENSAPLG00020005019, ENSAPLG00020010497, and ENSAPLG00020017682, as potential target genes that are crucial for myogenesis in the context of glycerolipid metabolism. These five mRNAs are integral to ceRNA networks, with miR-107_R-2 and miR-1260 emerging as key regulators. In summary, this study provides a valuable resource elucidating the intricate interplay of mRNA-lncRNA-circRNA-miRNA in duck myogenesis, shedding light on the molecular mechanisms that govern this critical biological process.

Gut-brain pathogenesis of post-acute COVID-19 neurocognitive symptoms

Approximately one third of non-hospitalized coronavirus disease of 2019 (COVID-19) patients report chronic symptoms after recovering from the acute stage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Some of the most persistent and common complaints of this post-acute COVID-19 syndrome (PACS) are cognitive in nature, described subjectively as "brain fog" and also objectively measured as deficits in executive function, working memory, attention, and processing speed. The mechanisms of these chronic cognitive sequelae are currently not understood. SARS-CoV-2 inflicts damage to cerebral blood vessels and the intestinal wall by binding to angiotensin-converting enzyme 2 (ACE2) receptors and also by evoking production of high levels of systemic cytokines, compromising the brain's neurovascular unit, degrading the intestinal barrier, and potentially increasing the permeability of both to harmful substances. Such substances are hypothesized to be produced in the gut by pathogenic microbiota that, given the profound effects COVID-19 has on the gastrointestinal system, may fourish as a result of intestinal post-COVID-19 dysbiosis. COVID-19 may therefore create a scenario in which neurotoxic and neuroinflammatory substances readily proliferate from the gut lumen and encounter a weakened neurovascular unit, gaining access to the brain and subsequently producing cognitive deficits. Here, we review this proposed PACS pathogenesis along the gut-brain axis, while also identifying specific methodologies that are currently available to experimentally measure each individual component of the model.

The potential of a combination of pungent spices as a novel supplement in gilthead seabream (Sparus aurata) diets to aid in the strategic use of fish oil in aquafeeds: a holistic perspective

This work studied the potential of a combination of pungent spices (capsicum, black pepper, ginger, and cinnamaldehyde) to be used as a supplement in diets of gilthead seabream (Sparus aurata; 44.1 ± 4.2 g). During 90 days, fish were fed three experimental diets with low inclusion of fish oil and containing poultry fat as the main source of lipids, supplemented with graded levels of the tested supplement: 0 (control), 0.1 (SPICY0.1%), and 0.15% (SPICY0.15%). As a result, the pungent spices enhanced the growth performance, the activity of the bile-salt-activated lipase in the intestine, and decreased fat deposit levels within enterocytes. The SPICY0.1% diet reduced the feed conversion ratio and the perivisceral fat index and lipid deposits in the liver. Moreover, the ratio of docosahexaenoic acid/eicosapentaenoic acid in fillet increased in fish fed the SPICY0.1% diet, while the hepatic levels of docosahexaenoic acid and total n-3 polyunsaturated fatty acids increased in fish fed the SPICY0.15% diet. Furthermore, there was an effect on the expression of some biomarkers related to lipid metabolism in 2-h postprandial fish (fasn, elovl6, scd1b, cyp7a1, lpl, and pparβ), and in 48 h fasted-fish fed with the SPICY0.1% diet, a regulation of the intestinal immune response was indicated. However, no significant differences were found in lipid apparent digestibility and proximate macronutrient composition. The spices did not affect biomarkers of hepatic or oxidative stress. No differences in microbial diversity were found, except for an increase in Simpson's Index in the posterior intestine of fish fed the SPICY0.1% diet, reflected in the increased relative abundance of the phylum Chloroflexi and lower relative abundances of the genera Campylobacter, Corynebacterium, and Peptoniphilus. In conclusion, the supplementation of gilthead seabream diets with pungent spices at an inclusion of 0.1% was beneficial to enhance growth performance and feed utilization; reduce fat accumulation in the visceral cavity, liver, and intestine; and improve the fish health status and condition. Results suggest that the tested supplement can be used as part of a nutritional strategy to promote a more judicious use of fish oil in fish diets due to its decreasing availability and rising costs.

Fecal and Circulating Biomarkers for the Non-Invasive Assessment of Intestinal Permeability

The study of intestinal permeability is gaining growing interest due to its relevance in the onset and progression of several gastrointestinal and non-gastrointestinal diseases. Though the involvement of impaired intestinal permeability in the pathophysiology of such diseases is recognized, there is currently a need to identify non-invasive biomarkers or tools that are able to accurately detect alterations in intestinal barrier integrity. On the one hand, promising results have been reported for novel in vivo methods based on paracellular probes, i.e., methods that can directly assess paracellular permeability and, on the other hand, on fecal and circulating biomarkers able to indirectly assess epithelial barrier integrity and functionality. In this review, we aimed to summarize the current knowledge on the intestinal barrier and epithelial transport pathways and to provide an overview of the methods already available or currently under investigation for the measurement of intestinal permeability.

Impact of Intracellular Lipid Binding Proteins on Endogenous and Xenobiotic Ligand Metabolism and Disposition

The family of intracellular lipid binding proteins (iLBPs) is comprised of 16 members of structurally related binding proteins that have ubiquitous tissue expression in humans. iLBPs collectively bind diverse essential endogenous lipids and xenobiotics. iLBPs solubilize and traffic lipophilic ligands through the aqueous milieu of the cell. Their expression is correlated with increased rates of ligand uptake into tissues and altered ligand metabolism. The importance of iLBPs in maintaining lipid homeostasis is well established. Fatty acid binding proteins (FABPs) make up the majority of iLBPs and are expressed in major organs relevant to xenobiotic absorption, distribution, and metabolism. FABPs bind a variety of xenobiotics including nonsteroidal anti-inflammatory drugs, psychoactive cannabinoids, benzodiazepines, antinociceptives, and peroxisome proliferators. FABP function is also associated with metabolic disease, making FABPs currently a target for drug development. Yet the potential contribution of FABP binding to distribution of xenobiotics into tissues and the mechanistic impact iLBPs may have on xenobiotic metabolism are largely undefined. This review examines the tissue-specific expression and functions of iLBPs, the ligand binding characteristics of iLBPs, their known endogenous and xenobiotic ligands, methods for measuring ligand binding, and mechanisms of ligand delivery from iLBPs to membranes and enzymes. Current knowledge of the importance of iLBPs in affecting disposition of xenobiotics is collectively described. SIGNIFICANCE STATEMENT: The data reviewed here show that FABPs bind many drugs and suggest that binding of drugs to FABPs in various tissues will affect drug distribution into tissues. The extensive work and findings with endogenous ligands suggest that FABPs may also alter the metabolism and transport of drugs. This review illustrates the potential significance of this understudied area.

Association of a high-fat diet with I-FABP as a biomarker of intestinal barrier dysfunction driven by metabolic changes in Wistar rats

BACKGROUND

The epithelial lining of the gut expresses intestinal fatty-acid binding proteins (I-FABPs), which increase in circulation and in plasma concentration during intestinal damage. From the perspective of obesity, the consumption of a diet rich in fat causes a disruption in the integrity of the gut barrier and an increase in its permeability.

HYPOTHESIS

There is an association between the expression of I-FABP in the gut and various metabolic changes induced by a high-fat (HF) diet.

METHODS

Wistar albino rats (n = 90) were divided into three groups (n = 30 per group), viz. One control and two HF diet groups (15 and 30%, respectively) were maintained for 6 weeks. Blood samples were thus collected to evaluate the lipid profile, blood glucose level and other biochemical tests. Tissue sampling was conducted to perform fat staining and immunohistochemistry.

RESULTS

HF diet-fed rats developed adiposity, insulin resistance, leptin resistance, dyslipidemia, and increased expression of I-FABP in the small intestine compared to the control group. Increased I-FABP expression in the ileal region of the intestine is correlated significantly with higher fat contents in the diet, indicating that higher I-FABP expression occurs due to increased demand of enterocytes to transport lipids, leading to metabolic alterations.

CONCLUSION

In summary, there is an association between the expression of I-FABP and HF diet-induced metabolic alterations, indicating that I-FABP can be used as a biomarker for intestinal barrier dysfunction.

The Clinical Significance of Serum Biomarkers of the Intestinal Barrier in Systemic Sclerosis: A Cross-Sectional Study

Systemic sclerosis (SSc) is an immune-mediated connective tissue disease. Recent studies reported differences in the composition of intestinal microbiota (dysbiosis) in patients with SSc compared to nonsclerodermic subjects. Dysbiosis may disrupt the intestinal barrier, which leads to immunological activation via microbial antigen and metabolite translocation. The study aimed to assess the differences in intestinal permeability between SSc patients and controls and to examine the correlation between intestinal permeability and complications of SSc. The study comprised 50 patients with SSc and 30 matched subjects. Serum intestinal permeability markers: intestinal fatty acid binding protein, claudin-3, and lipopolysaccharides (LPS) were determined using an enzyme-linked immunosorbent assay. SSc patients had a significantly increased concentration of LPS compared to control subjects (232.30 [149.00-347.70] versus 161.00 [83.92-252.20] pg/mL, p < 0.05). The patients with shorter SSc duration (≤6 years) had an increased concentration of LPS and claudin-3 compared to the subgroup with longer disease length: LPS (280.75 [167.30-403.40] versus 186.00 [98.12-275.90] pg/mL, p < 0.05), and claudin-3 (16.99 [12.41-39.59] versus 13.54 [10.29-15.47] ng/mL, p < 0.05). The patients with esophageal dysmotility had a decreased LPS level compared to those without this complication (188.05 [102.31-264.40] versus 283.95 [203.20-356.30] pg/mL, p < 0.05). Increased intestinal permeability in SSc may exacerbate the course of the disease and increase the risk of developing complications. Lower LPS levels in SSc might be a hallmark of esophageal dysmotility.

Small Intestinal Digestive Functions and Feed Efficiency Differ in Different Pig Breeds

Small intestinal growth and health affect its digestion and absorption ability, while little information exists about the small intestinal morphology and function differences among the different pig breeds. Therefore, 90 healthy 35 days of age Taoyuan black (TB), Xiangcun black (XB), and Duroc (DR) pigs (30 pigs per breed) with similar body weight (BW) of the same breed were reared to 185 days of age to evaluate the potential relationship between feed efficiency and small intestinal morphology and function at 80, 125, and 185 days of age. The results show that the TB and XB pigs had lower initial and final BW, ADG, and ADFI and plasma CHO and LDL-C levels, whereas they had higher plasma LIP levels and jejunal trypsin, invertase, lactase, and maltase activities and higher DM, ADF, Tyr, Arg, and His digestibility at 80 days of age compared with the DR pigs. At 125 days of age, TB and XB pigs had lower apparent total tract digestibility and plasma CHO, HDL-C, LDL-C, and NH3 levels; XB pigs had lower DM and NDF digestibility, and TB pigs had higher jejunal lactase and maltase activities. At 185 days of age, TB and XB pigs had lower DM, EE, ADF, and GE digestibility, while having higher plasma ALT and UN levels; TB pigs had higher plasma AST level and jejunal chymase activity. Furthermore, the plasma free amino acid contents, small intestinal VH, and nutrient transporter expression levels differed at different ages. Therefore, the different pig breeds exhibited significantly different growth performance and small intestinal growth, mainly resulting from the differences in digestive enzymes and nutrient transporters in the small intestine.

Biomarkers of gut barrier dysfunction in obstructive sleep apnea: A systematic review and meta-analysis

We conducted this systematic review and meta-analysis to evaluate the impact of obstructive sleep apnea (OSA) on gut barrier dysfunction as represented by the following biomarkers: zonulin, lipopolysaccharide, lipopolysaccharide binding protein, intestinal fatty acid binding protein, and lactic acid. A comprehensive search of the literature was conducted in Ovid MEDLINE, Embase, Scopus, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov without language restrictions from inception to October 2022. The analysis of all outcomes was performed using a random-effects model. We included eight studies (seven cross sectional and one case control) in the final quantitative synthesis with a total of 897 patients. We concluded that OSA was associated with higher levels of gut barrier dysfunction biomarkers [Hedges' g = 0.73 (95%CI 0.37-1.09, p < 0.01). Biomarker levels were positively correlated with the apnea-hypopnea index [r = 0.48 (95%CI 0.35-0.6, p < 0.01)] and oxygen desaturation index [r = 0.30 (95%CI 0.17-0.42, p < 0.01)], and negatively correlated with the nadir oxygen desaturation values [r = -0.45 (95%CI - 0.55 - - 0.32, p < 0.01). Our systematic review and meta-analysis suggests that OSA is associated with gut barrier dysfunction. Furthermore, OSA severity appears to be correlated with higher biomarkers of gut barrier dysfunction. PROSPERO REGISTRATION NUMBER: CRD42022333078.

Enterocyte-specific deletion of metal transporter Zip14 (Slc39a14) alters intestinal homeostasis through epigenetic mechanisms

Zinc has anti-inflammatory properties using mechanisms that are unclear. Zip14 (Slc39a14) is a zinc transporter induced by proinflammatory stimuli and is highly expressed at the basolateral membrane of intestinal epithelial cells (IECs). Enterocyte-specific Zip14 ablation (Zip14ΔIEC) in mice was developed to study the functions of this transporter in enterocytes. This gene deletion led to increased intestinal permeability, increased IL-6 and IFNγ expression, mild endotoxemia, and intestinal dysbiosis. RNA sequencing was used for transcriptome profiling. These analyses revealed differential expression of specific intestinal proinflammatory and tight junction (TJ) genes. Binding of transcription factors, including NF-κβ, STAT3, and CDX2, to appropriate promoter sites of these genes supports the differential expression shown with chromatin immunoprecipitation assays. Total histone deacetylase (HDAC), and specifically HDAC3, activities were markedly reduced with Zip14 ablation. Intestinal organoids derived from ΔIEC mice display TJ and cytokine gene dysregulation compared with control mice. Differential expression of specific genes was reversed with zinc supplementation of the organoids. We conclude that zinc-dependent HDAC enzymes acquire zinc ions via Zip14-mediated transport and that intestinal integrity is controlled in part through epigenetic modifications.NEW & NOTEWORTHY We show that enterocyte-specific ablation of zinc transporter Zip14 (Slc39a14) results in selective dysbiosis and differential expression of tight junction proteins, claudin 1 and 2, and specific cytokines associated with intestinal inflammation. HDAC activity and zinc uptake are reduced with Zip14 ablation. Using intestinal organoids, the expression defects of claudin 1 and 2 are resolved through zinc supplementation. These novel results suggest that zinc, an essential micronutrient, influences gene expression through epigenetic mechanisms.

Plasma levels and tissue expression of liver-type fatty acid-binding protein in patients with breast cancer

BACKGROUND

Liver-type fatty acid-binding protein (L-FABP) is widely expressed in hepatocytes and plays a role in lipid metabolism. It has been demonstrated to be overexpressed in different types of cancer; however, few studies have investigated the association between L-FABP and breast cancer. The aim of this study was to assess the association between plasma concentrations of L-FABP in breast cancer patients and the expression of L-FABP in breast cancer tissue.

METHOD

A total of 196 patients with breast cancer and 57 age-matched control subjects were studied. Plasma L-FABP concentrations were measured using ELISA in both groups. The expression of L-FABP in breast cancer tissue was examined using immunohistochemistry.

RESULT

The patients had higher plasma L-FABP levels than the controls (7.6 ng/mL (interquartile range 5.2-12.1) vs. 6.3 ng/mL (interquartile range 5.3-8.5), p = 0.008). Multiple logistic regression analysis showed an independent association between L-FABP and breast cancer, even after adjusting for known biomarkers. Moreover, the rates of pathologic stage T2+T3+T4, clinical stage III, positive HER-2 receptor status, and negative estrogen receptor status were significantly higher in the patients with an L-FABP level greater than the median. Furthermore, the L-FABP level gradually increased with the increasing stage. In addition, L-FABP was detected in the cytoplasm, nuclear, or both cytoplasm and nuclear of all breast cancer tissue examined, not in the normal tissue.

CONCLUSIONS

Plasma L-FABP levels were significantly higher in the patients with breast cancer than in the controls. In addition, L-FABP was expressed in breast cancer tissue, which suggests that L-FABP may be involved in the pathogenesis of breast cancer.

Role of functional fatty acids in modulation of reproductive potential in livestock

Fatty acids are not only widely known as energy sources, but also play important roles in many metabolic pathways. The significance of fatty acids in modulating the reproductive potential of livestock has received greater recognition in recent years. Functional fatty acids and their metabolites improve follicular development, oocyte maturation and embryo development, as well as endometrial receptivity and placental vascular development, through enhancing energy supply and precursors for the synthesis of their productive hormones, such as steroid hormones and prostaglandins. However, many studies are focused on the impacts of individual functional fatty acids in the reproductive cycle, lacking studies involved in deeper mechanisms and optimal fatty acid requirements for specific physiological stages. Therefore, an overall consideration of the combination and synergy of functional fatty acids and the establishment of optimal fatty acid requirement for specific stages is needed to improve reproductive potential in livestock.

Fat digestion and metabolism: effect of different fat sources and fat mobilisers in broilers diet on growth performance and physiological parameters – a review

Commercial broilers have a short production cycle and a high requirement for energy (3000 kcal/kg in starter phase and 3200 kcal/kg in finisher phase). Therefore, the need to add energy rich lipids to their diet is inevitable. Digestibility of fat depends on its multiple properties: chain length, the composition of fatty acids, ratio of saturated/unsaturated fatty acids and free fatty acids. The high cost of vegetable oils and less availability due to their consumption in human diet are the main reasons for searching cheaper alternative fat sources. Animal oils like poultry and fish oil are the by-product of rendering plants and after refining, they are used in poultry diets as an energy source. Due to presence of impurities and free fatty acids, the digestibility of animal fat is less. There is a limited amount of bile acids and lipase available during early age and when birds are reared on high energy diet (finisher phase). Supplementation of emusifier or lipase in broilers diet increase fat utilisation. Emulsifiers increase fat digestibility by increasing active surface area of lipid droplets. Lysolecithin and Lysophospholipids are produced from hydrolyses of lecithin and phospholipids by phopholipase A2. The bile acids mainly compose of cholic acid, hyodeoxycholic acid and chenodeoxycholic acid and have strong emulsification properties. Triacylglyceryl acylase (lipase) is an enzyme involved in catalysis and the hydrolysis of lipids. It can be concluded that use of emulsifier and lipase in broilers diet improves growth performance, nutrient digestibility and intestinal histology in broilers.

Intestinal Barrier Dysfunction and Microbial Translocation in Patients with First-Diagnosed Atrial Fibrillation

BACKGROUND

According to the leaky gut concept, microbial products (e.g., lipopolysaccharide, LPS) enter the circulation and mediate pro-inflammatory immunological responses. Higher plasma LPS levels have been reported in patients with various cardiovascular diseases, but not specifically during early atrial fibrillation (AF).

METHODS

We studied data and blood samples from patients presenting with first-diagnosed AF (FDAF) (n = 80) and 20 controls.

RESULTS

Circulating biomarkers that are suggestive of mucosal inflammation (zonulin, mucosal adhesion molecule MAdCAM-1) and intestinal epithelium damage (intestinal fatty acid binding protein, IFABP) were increased in the plasma of patients with FDAF when compared to patients with chronic cardiovascular diseases but without AF. Surrogate plasma markers of increased intestinal permeability (LPS, CD14, LPS-binding protein, gut-derived LPS-neutralising IgA antibodies, EndoCAbs) were detected during early AF. A reduced ratio of IgG/IgM EndoCAbs titres indicated chronic endotoxaemia. Collagen turnover biomarkers, which corresponded to the LPS values, suggested an association of gut-derived low-grade endotoxaemia with adverse structural remodelling. The LPS concentrations were higher in FDAF patients who experienced a major adverse cardiovascular event.

CONCLUSIONS

Intestinal barrier dysfunction and microbial translocation accompany FDAF. Improving gut permeability and low-grade endotoxaemia might be a potential therapeutic approach to reducing the disease progression and cardiovascular complications in FDAF.

Proteomic, biochemical, histopathological, and elevated plus maze analysis reveals the gut damaging role of ketoprofen with Yersinia enterocolitica and altered behavior in Wistar rats

The long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) is known to damage the intestinal epithelial cells (IECs) that play numerous important roles, including nutrient absorption and barrier protection. In the current study, we determined the effect of ketoprofen on the rat gut when administered with Yersinia enterocolitica. On performing the label-free quantitation of the rat gut proteins, the expression of 494 proteins out of 1628 proteins was altered, which has a profound effect on NF-kB signaling pathway, immune system, dysbiosis, and gut injury. Further, the biochemical [enhanced malondialdehyde (MDA) & hepatic enzyme activities and reduced serotonin & antioxidants levels i.e., catalase (CAT) and superoxide dismutase (SOD)] and histopathological analysis suggested the significant damage in treated rats, compared to control rats. Lastly, the elevated plus maze (EPM) study confirmed high levels of anxiety in treated rats in comparison to the control group. Altogether, results suggest that the co-administration of ketoprofen with Y. enterocolitica damages gut, alters hepatic enzyme activities, and affects behavioral responses in the treated rats.

Reduced circulating FABP2 in patients with moderate to severe COVID-19 may indicate enterocyte functional change rather than cell death

The gut is of importance in the pathology of COVID-19 both as a route of infection, and gut dysfunction influencing the severity of disease. Systemic changes caused by SARS-CoV-2 gut infection include alterations in circulating levels of metabolites, nutrients and microbial products which alter immune and inflammatory responses. Circulating plasma markers for gut inflammation and damage such as zonulin, lipopolysaccharide and β-glycan increase in plasma along with severity of disease. However, Intestinal Fatty Acid Binding Protein / Fatty Acid Binding Protein 2 (I-FABP/FABP2), a widely used biomarker for gut cell death, has paradoxically been shown to be reduced in moderate to severe COVID-19. We also found this pattern in a pilot cohort of mild (n = 18) and moderately severe (n = 19) COVID-19 patients in Milan from March to June 2020. These patients were part of the first phase of COVID-19 in Europe and were therefore all unvaccinated. After exclusion of outliers, patients with more severe vs milder disease showed reduced FABP2 levels (median [IQR]) (124 [368] vs. 274 [558] pg/mL, P < 0.01). A reduction in NMR measured plasma relative lipid-CH3 levels approached significance (median [IQR]) (0.081 [0.011] vs. 0.073 [0.024], P = 0.06). Changes in circulating lipid levels are another feature commonly observed in severe COVID-19 and a weak positive correlation was observed in the more severe group between reduced FABP2 and reduced relative lipid-CH3 and lipid-CH2 levels. FABP2 is a key regulator of enterocyte lipid import, a process which is inhibited by gut SARS-CoV-2 infection. We propose that the reduced circulating FABP2 in moderate to severe COVID-19 is a marker of infected enterocyte functional change rather than gut damage, which could also contribute to the development of hypolipidemia in patients with more severe disease.

Electroacupuncture promoted intestinal defensins and rescued the dysbiotic cecal microbiota of high-fat diet-induced obese mice

Obesity is currently one of the most important challenges to public health worldwide. Acupuncture has been widely used to treat obesity. However, whether acupuncture regulates intestinal innate immunity via intestinal microbiota against obesity remains to be elucidated. In this study, electroacupuncture (EA) effectively reduced body weight and fat accumulation in obese mice persistently fed a high-fat diet. Full-length 16S rDNA sequencing showed dysbiotic microbiota in the cecum of obese mice. The composition and function of the cecal microbiota of obese mice were markedly restored after EA treatment. After 21 d of EA intervention, the expression of defensin alpha 5 (Defa5) was restored to healthy controls, whereas fat digestion and absorption genes including fabp1 were markedly decreased in the jejunum of obese mice. The Defa5 levels were positively correlated with the family Lachnospiraceae and negatively correlated with obesity indexes. EA also reduced tissue inflammation, ameliorated misaligned glucose tolerance, and inhibited key genes for intestinal lipid absorption. In summary, EA exerted an anti-obesity effect by promoting intestinal defensins, rescuing dysbiotic cecal microbiota, and reducing lipid absorption in a synergistic mode. We present for the first time the key role of alpha defensins in the relationship between gut microbiota and disease during electroacupuncture treatment of obesity. The mucosal innate immunity seems to have a stronger ability to shape the microbiota than dietary factors.

Fatty Acid-Binding Proteins: Their Roles in Ischemic Stroke and Potential as Drug Targets

Stroke is among the leading causes of death and disability worldwide. However, despite long-term research yielding numerous candidate neuroprotective drugs, there remains a lack of effective neuroprotective therapies for ischemic stroke patients. Among the factors contributing to this deficiency could be that single-target therapy is insufficient in addressing the complex and extensive mechanistic basis of ischemic brain injury. In this context, lipids serve as an essential component of multiple biological processes and play important roles in the pathogenesis of numerous common neurological diseases. Moreover, in recent years, fatty acid-binding proteins (FABPs), a family of lipid chaperone proteins, have been discovered to be involved in the onset or development of several neurodegenerative diseases, including Alzheimer's and Parkinson's disease. However, comparatively little attention has focused on the roles played by FABPs in ischemic stroke. We have recently demonstrated that neural tissue-associated FABPs are involved in the pathological mechanism of ischemic brain injury in mice. Here, we review the literature published in the past decade that has reported on the associations between FABPs and ischemia and summarize the relevant regulatory mechanisms of FABPs implicated in ischemic injury. We also propose candidate FABPs that could serve as potential therapeutic targets for ischemic stroke.

Betaine Reduces Lipid Anabolism and Promotes Lipid Transport in Mice Fed a High-Fat Diet by Influencing Intestinal Protein Expression

Betaine is more efficient than choline and methionine methyl donors, as it can increase nitrogen storage, promote fat mobilisation and fatty acid oxidation and change body fat content and distribution. Lipid is absorbed primarily in the small intestine after consumption, which is also the basis of lipid metabolism. This study was conducted to establish a mouse model of obesity in Kunming mice of the same age and similar body weight, and to assess the effect of betaine on the intestinal protein expression profile of mice using a proteomic approach. Analysis showed that betaine supplementation reversed the reduction in expression of proteins related to lipid metabolism and transport in the intestine of mice induced by a high-fat diet (HFD). For example, the addition of betaine resulted in a significant upregulation of microsomal triglyceride transfer protein (Mttp), apolipoprotein A-IV (Apoa4), fatty-acid-binding protein 1 (Fabp1) and fatty-acid-binding protein 2 (Fabp2) expression compared to the HFD group (p < 0.05), which exhibited accelerated lipid absorption and then translocation from the intestine into the body’s circulation, in addition to a significant increase in Acetyl-CoA acyltransferase (Acaa1a) protein expression, hastening lipid metabolism in the intestine (p < 0.05). Simultaneously, a significant reduction in protein expression of alpha-enolase 1 (Eno1) as the key enzyme for gluconeogenesis in mice in the betaine-supplemented group resulted in a reduction in lipid synthesis in the intestine (p < 0.05). These findings provide useful information for understanding the changes in the protein profile of the small intestine in response to betaine supplementation and the potential physiological regulation of diets’ nutrient absorption.

Differential expression of MSTN, IGF2BP1, and FABP2 across different embryonic ages and sexes in white Muscovy ducks

To explore the effects of growth-related genes in both sexes and at different growth and development stages, male and female white Muscovy ducks at embryonic day E13, E17, E21, E25 and E29 were assessed in this study. RT-qPCR was used to determine the mRNA transcription levels of selected growth-related genes in the leg muscles of Muscovy ducks of both sexes and at different growth and developmental stages. MSTN, IGF2BP1 and FABP2 mRNAs were expressed in the leg muscles of male and female Muscovy ducks, but with different expression patterns. The MSTN and IGF2BP1 mRNA expression patterns were wavelike. MSTN mRNA expression was elevated at E13, increased at E17, decreased rapidly to the lowest level at E21, increased again at E25, and then decreased. IGF2BP1 mRNA expression was elevated at E13, increased at E17, decreased rapidly at E21, decreased rapidly to the lowest level at E25, and increased at E29. The expression trend of FABP2 mRNA was approximately "⊥" shape; the expression was the lowest at E13, increased slowly from E17 to E25, and increased extremely significantly at E29. In addition, the expression of MSTN in male Muscovy ducks was significantly higher than that in female ducks at E25 (P < 0.05). The expression of IGF2BP1 in male Muscovy ducks was extremely significantly higher than that in female ducks at E17 (P < 0.01). However, the expression of FABP2 in female Muscovy ducks was extremely significantly higher than that in male Muscovy ducks at E21 and E29 (P < 0.01). In conclusion, the mRNA expression of MSTN, IGF2BP1 and FABP2 in white Muscovy ducks is gestational age specific and sex specific. The differential gene expression patterns observed in this study provide a basis for understanding the physiological changes in white Muscovy ducks at different embryonic ages and in both sexes, supplementing the existing research on duck embryo muscle development. In addition, the findings provide a new framework for further discussion of poultry breeding.

Topical VX-509 attenuates psoriatic inflammation through the STAT3/FABP5 pathway in keratinocytes

BACKGROUND

Psoriasis is a chronic inflammatory disease, with lesions mainly manifesting as scaly erythematous plaques. The mild or moderate of psoriasis is the main type of patients in hospital, and topical application remains the preferred treatment option for psoriasis therapy, therefore, the development of novel topical agents has an essential role in psoriasis therapy.

OBJECTIVE

To identify potential drugs for psoriasis topical treatment.

METHODS

We performed drug screening by Imiquimod (IMQ)-induced psoriatic like inflammation in mouse model, followed mouse epidermis by RNA-seq to find the key molecules affecting the drug. The qRT-PCR, WB were performed to test mRNA and protein expression, and Chip assay had been conducted to examine Stat3 bound to promoter of FABP5.

RESULTS

In this study, we identified VX-509, which topical application significantly attenuated IMQ-induced psoriatic like inflammation in mouse model. And then, we verified Epidermal Fatty acid binding protein (E-FABP/FABP5) was significantly decreased in VX-509 treated mouse epidermis by RNA-seq. FABP5 is a key molecule in lipid metabolism, administration of FABP5 inhibitor or knock down of FABP5 expression remarkably abrogated psoriatic inflammation as well as lipid metabolism. Mechanistically, our finding showed that VX-509 blocked IL-22 induced signaling pathway, particular in activation of Stat3. Furthermore, we identified Stat3 is a transcriptional factor associated with FABP5 promoters and VX-509 treatment remarkably attenuated IL-22-induced FABP5 expression through Stat3 in KCs.

CONCLUSIONS

This study demonstrated administration of VX-509 is a potential promising topical drug for treatment of psoriasis, FABP5 is a critical targeted molecule in psoriasis therapy.

Association between preoperative nutritional status, inflammation, and intestinal permeability in elderly patients undergoing gastrectomy: a prospective cohort study

Background

Malnutrition is relatively common among elderly patients with gastric cancer. This study sought to analyze whether preoperative nutritional status, inflammatory cytokines, and intestinal permeability were correlated in elderly gastric cancer patients undergoing surgery, and their effects on postoperative recovery.

Methods

This study was a single-center prospective cohort study. Patients aged 65-90 years who underwent gastrectomy were included. Preoperative nutritional status was assessed by the Mini Nutritional Score (MNA), Nutritional Risk Screening-2002 (NRS2002), body mass index (BMI), free fatty acids (FFAs), albumin, and prealbumin concentrations. Intestinal permeability was assessed by D-lactate and intestinal fatty acid-binding protein (i-FABP). The inflammatory factors included interleukin (IL)-6, IL-10, neutrophil, and lymphocyte counts. The time to first defecation, time to first liquid diet, length of hospital stay (LOS), and postoperative complications were recorded.

Results

A total of 134 patients were included. According to the MNA, 50.7% and 32.1% of the cohort had mild to moderate malnutrition, and severe malnutrition, respectively. According to the NRS2002, 38.8% of the patients scored >4 points. I-FABP was significantly negatively correlated with albumin (r=-0.409, P<0.001) and prealbumin (r=-0.397, P<0.001), and significantly positively correlated with MNA (r=0.291, P=0.001), the NRS2002 (r=0.284, P=0.001), and LOS (r=0.245, P=0.004). D-lactate was significantly negatively correlated with BMI (r=-0.229, P=0.008), albumin (r=-0.426, P<0.001), and prealbumin (r=-0.358, P<0.001), and significantly positively correlated with the NRS2002 (r=0.187, P=0.030), time to first defecation (r=0.264, P=0.002), and LOS (r=0.409, P<0.001). There were significant differences in BMI, prealbumin, FFAs, i-FABP, time to first defecation, and time to first fluid diet (P<0.05) among groups based on MNA score. The multivariate logistic analysis showed that D-lactate was an independent risk factor of postoperative complications [odds ratio (OR) =1.354, 95% confidence interval (CI): 1.099-1.669, P=0.004].

Conclusions

The preoperative intestinal permeability indicators (i.e., D-lactate and i-FABP) are significantly correlated with some nutritional indicators and postoperative recovery indicators. The preoperative D-lactate level is an independent risk factor of postoperative complications, suggesting that altered gut barrier function before surgery could to some extent influence postoperative recovery in the elderly.

Time-Series Clustering of lncRNA-mRNA Expression during the Adipogenic Transdifferentiation of Porcine Skeletal Muscle Satellite Cells

Skeletal muscle satellite cells (SMSCs), which are multifunctional muscle-derived stem cells, can differentiate into adipocytes. Long-chain non-coding RNA (lncRNA) has diverse biological functions, including the regulation of gene expression, chromosome silencing, and nuclear transport. However, the regulatory roles and mechanism of lncRNA during adipogenic transdifferentiation in muscle cells have not been thoroughly investigated. Here, porcine SMSCs were isolated, cultured, and induced for adipogenic differentiation. The expressions of lncRNA and mRNA at different time points during transdifferentiation were analysed using RNA-seq analysis. In total, 1005 lncRNAs and 7671 mRNAs showed significant changes in expression at differential differentiation stages. Time-series expression analysis showed that the differentially expressed (DE) lncRNAs and mRNAs were clustered into 5 and 11 different profiles with different changes, respectively. GO, KEGG, and REACTOME enrichment analyses revealed that DE mRNAs with increased expressions during the trans-differentiation were mainly enriched in the pathways for lipid metabolism and fat cell differentiation. The genes with decreased expressions were mainly enriched in the regulation of cell cycle and genetic information processing. In addition, 1883 DE mRNAs were regulated by 193 DE lncRNAs, and these genes were related to the controlling in cell cycle mainly. Notably, three genes in the fatty acid binding protein (FABP) family significantly and continuously increased during trans-differentiation, and 15, 13, and 11 lncRNAs may target FABP3, FABP4, and FABP5 genes by cis- or trans-regulation, respectively. In conclusion, these studies identify a set of new potential regulator for adipogenesis and cell fate and help us in better understanding the molecular mechanisms of trans-differentiation.

The Infection, Coinfection, and Abundance of Intestinal Protozoa Increase the Serum Levels of IFABP2 and TNF-α in Patients With Rheumatoid Arthritis

Protozoa, nematodes, and platyhelminths are of clinical interest due to their role on the modulation of the immune responses. To determine the frequency of infection by intestinal parasites as well as the status of single or mixed infection (coinfection) and its relation with inflammation and intestinal permeability markers in patients with rheumatoid arthritis (RA), a cross-sectional study was conducted in 18 women diagnosed with RA. A fecal sample of each participant was analyzed for parasitic identification. The DAS28-erythrocyte sedimentation rate score, as well as the serum levels of TNF-α, IL-10, IL-17A, and the intestinal fatty-acid binding protein 2 (IFABP2), was determined through the ELISA technique. The T CD4+ and CD8+ lymphocytes' proportions were determined by flow cytometry. In this study, 50% (n = 9) of the total sample tested were positive to the presence of intestinal protozoa (27% by single infection and 22.2% by coinfection). Blastocystis sp. and Endolimax nana were the most frequently identified protozoa. The serum levels of IFABP2 were increased in patients with infection by protozoa, mainly in those individuals with coinfection and a larger abundance of Blastocystis sp. We found that coinfection by protozoa was related to higher levels of TNF-α and higher frequency of T CD4+ lymphocytes, mainly in patients under antirheumatic treatment. Infection by intestinal protozoa is associated with increased intestinal permeability in patients with RA; thus, infection, coinfection, and abundance of intestinal protozoa should be clinically screened because they could be an associated factor to the clinical variability of the disease.

Fecal microbiota transfer between young and aged mice reverses hallmarks of the aging gut, eye, and brain

BACKGROUND

Altered intestinal microbiota composition in later life is associated with inflammaging, declining tissue function, and increased susceptibility to age-associated chronic diseases, including neurodegenerative dementias. Here, we tested the hypothesis that manipulating the intestinal microbiota influences the development of major comorbidities associated with aging and, in particular, inflammation affecting the brain and retina.

METHODS

Using fecal microbiota transplantation, we exchanged the intestinal microbiota of young (3 months), old (18 months), and aged (24 months) mice. Whole metagenomic shotgun sequencing and metabolomics were used to develop a custom analysis workflow, to analyze the changes in gut microbiota composition and metabolic potential. Effects of age and microbiota transfer on the gut barrier, retina, and brain were assessed using protein assays, immunohistology, and behavioral testing.

RESULTS

We show that microbiota composition profiles and key species enriched in young or aged mice are successfully transferred by FMT between young and aged mice and that FMT modulates resulting metabolic pathway profiles. The transfer of aged donor microbiota into young mice accelerates age-associated central nervous system (CNS) inflammation, retinal inflammation, and cytokine signaling and promotes loss of key functional protein in the eye, effects which are coincident with increased intestinal barrier permeability. Conversely, these detrimental effects can be reversed by the transfer of young donor microbiota.

CONCLUSIONS

These findings demonstrate that the aging gut microbiota drives detrimental changes in the gut-brain and gut-retina axes suggesting that microbial modulation may be of therapeutic benefit in preventing inflammation-related tissue decline in later life. Video abstract.

Gut Microbiota and Phenotypic Changes Induced by Ablation of Liver- and Intestinal-Type Fatty Acid-Binding Proteins

Intestinal fatty acid-binding protein (IFABP; FABP2) and liver fatty acid-binding protein (LFABP; FABP1) are small intracellular lipid-binding proteins. Deficiency of either of these proteins in mice leads to differential changes in intestinal lipid transport and metabolism, and to markedly divergent changes in whole-body energy homeostasis. The gut microbiota has been reported to play a pivotal role in metabolic process in the host and can be affected by host genetic factors. Here, we examined the phenotypes of wild-type (WT), LFABP-/-, and IFABP-/- mice before and after high-fat diet (HFD) feeding and applied 16S rRNA gene V4 sequencing to explore guild-level changes in the gut microbiota and their associations with the phenotypes. The results show that, compared with WT and IFABP-/- mice, LFABP-/- mice gained more weight, had longer intestinal transit time, less fecal output, and more guilds containing bacteria associated with obesity, such as members in family Desulfovibrionaceae. By contrast, IFABP-/- mice gained the least weight, had the shortest intestinal transit time, the most fecal output, and the highest abundance of potentially beneficial guilds such as those including members from Akkermansia, Lactobacillus, and Bifidobacterium. Twelve out of the eighteen genotype-related bacterial guilds were associated with body weight. Interestingly, compared with WT mice, the levels of short-chain fatty acids in feces were significantly higher in LFABP-/- and IFABP-/- mice under both diets. Collectively, these studies show that the ablation of LFABP or IFABP induced marked changes in the gut microbiota, and these were associated with HFD-induced phenotypic changes in these mice.