Arginine and citrulline protect intestinal cell monolayer tight junctions from hypoxia-induced injury in piglets

Enteral L-citrulline supplementation in preterm infants is safe and effective in increasing plasma arginine and citrulline levels-a pilot randomized trial

OBJECTIVE

Deficiencies of citrulline and arginine have been associated with adverse outcomes in preterm-infants and data regarding enteral supplementation in preterm infants is limited.

STUDY DESIGN

This randomized -trial [NCT03649932] included 42 preterm infants (gestational age ≤33 weeks) randomized to receive enteral L-citrulline in low (100 mg/kg/day), medium (200 mg/kg/day) and high-dose (300 mg/kg/day) groups for 7 days. Plasma citrulline and arginine levels were obtained pre-and-post supplementation and efficacy was determined by a significant increase in levels after supplementation. A p < 0.05 was considered significant. Safety monitoring included blood-pressure-monitoring as well as complications and death during hospitalization.

RESULTS

A total of 40/42 (95%) of the recruits completed the 7-day supplementation with no adverse events. Plasma-citrulline levels increased significantly in all three groups while plasma-arginine levels increased significantly in the high-dose group.

CONCLUSION

Enteral L-citrulline supplementation in preterm infants is safe and effective in increasing plasma citrulline and arginine levels.

CLINICAL TRIAL REGISTRATION

NCT03649932 https://clinicaltrials.gov/ct2/show/NCT03649932 .

Effects of supplemental citrulline on thermal and intestinal morphology parameters during heat stress and feed restriction in growing pigs

Study objectives were to characterize the effects of citrulline (CIT) on physiological and intestinal morphology metrics during heat stress (HS) and feed restriction. Forty crossbred gilts (30 ± 2 kg body weight [BW]) were assigned to one of five treatments: (1) thermoneutral (TN) fed ad libitum (AL) with control (CON) supplement (TNAL; n = 8), (2) TN pair-fed (PF) with CON (PF-CON; n = 8), (3) TN PF with CIT (PF-CIT; n = 8), (4) HS AL with CON (HS-CON; n = 8), and (5) HS AL with CIT (HS-CIT; n = 8). During the period (P) 1 (7 d), pigs were in TN conditions (23.6 °C) and fed AL their respective supplemental treatments. During P2 (2.5 d), HS-CON and HS-CIT pigs were fed AL and exposed to cyclical HS (33.6 to 38.3 °C), while TNAL, PF-CON, and PF-CIT remained in TN and were fed either AL or PF to their HS counterparts. Citrulline (0.13 g/kg BW) was orally administered twice daily during P1 and P2. HS increased rectal temperature (Tr), skin temperature (Ts), and respiration rate (RR) relative to TN pigs (0.8 °C, 4.7 °C, and 47 breaths/min, respectively; P < 0.01). However, HS-CIT had decreased RR (7 breaths/min, P = 0.04) and a tendency for decreased Tr (0.1 °C, P = 0.07) relative to HS-CON pigs. During P2, HS pigs had decreased feed intake (22%; P < 0.01) and a tendency for decreased average daily gain (P = 0.08) relative to TNAL pigs, and by experimental design, PF pigs followed this same pattern. Circulating lipopolysaccharide-binding protein tended to be decreased (29%; P = 0.08) in PF relative to TNAL pigs and was increased (41%; P = 0.03) in HS compared to PF pigs. Jejunum villus height was decreased in PF relative to TNAL pigs (15%; P = 0.03); however, CIT supplementation improved this metric during feed restriction (16%; P = 0.10). Jejunum mucosal surface area decreased in PF (16%; P = 0.02) and tended to decrease in HS (11%; P = 0.10) compared to TNAL pigs. Ileum villus height and mucosal surface area decreased in HS compared to TNAL pigs (10 and 14%, respectively; P ≤ 0.04), but both parameters were rescued by CIT supplementation (P ≤ 0.08). Intestinal myeloperoxidase and goblet cell area remained similar among treatments and intestinal segments (P > 0.24). In summary, CIT supplementation slightly improved RR and Tr during HS. Feed restriction and HS differentially affected jejunum and ileum morphology and while CIT ameliorated some of these effects, the benefit appeared dependent on intestinal section and stressor type.

Leaky Gut and the Ingredients That Help Treat It: A Review

The human body is in daily contact with potentially toxic and infectious substances in the gastrointestinal tract (GIT). The GIT has the most significant load of antigens. The GIT can protect the intestinal integrity by allowing the passage of beneficial agents and blocking the path of harmful substances. Under normal conditions, a healthy intestinal barrier prevents toxic elements from entering the blood stream. However, factors such as stress, an unhealthy diet, excessive alcohol, antibiotics, and drug consumption can compromise the composition of the intestinal microbiota and the homeostasis of the intestinal barrier function of the intestine, leading to increased intestinal permeability. Intestinal hyperpermeability can allow the entry of harmful agents through the junctions of the intestinal epithelium, which pass into the bloodstream and affect various organs and systems. Thus, leaky gut syndrome and intestinal barrier dysfunction are associated with intestinal diseases, such as inflammatory bowel disease and irritable bowel syndrome, as well as extra-intestinal diseases, including heart diseases, obesity, type 1 diabetes mellitus, and celiac disease. Given the relationship between intestinal permeability and numerous conditions, it is convenient to seek an excellent strategy to avoid or reduce the increase in intestinal permeability. The impact of dietary nutrients on barrier function can be crucial for designing new strategies for patients with the pathogenesis of leaky gut-related diseases associated with epithelial barrier dysfunctions. In this review article, the role of functional ingredients is suggested as mediators of leaky gut-related disorders.

Water- and feed-based arginine impacts on gut integrity in weanling pigs

Two hundred and forty newly weaned pigs (PIC, Hendersonville, TN) were used to determine if supplementing additional arginine (Arg) either in the water or in the feed, and the combinations thereof, improved intestinal integrity and growth performance in nursery pigs. Each of the 80 pens contained three pigs (21 ± 2 d of age) which were randomly allotted to treatments in 4 × 3 factorial arrangement consisting of four water treatments (0%, 4%, 8%, and 12% Arg stock delivered through a 1:128 medication delivery system) in combination with three dietary Arg treatments (1.35%, 1.55%, and 1.75% standardized ileal digestible Arg; SID). Pigs and feeders were weighed at the d0, d6 (water and diet change), d20 (diet change), and d41 for the calculation of average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (G:F). Eighty pigs, 1 pig/pen, were euthanized at d6 for ileum evaluation of villus height and crypt depth. The remaining pigs were taken off the Arg-water treatment and fed phase-2 diets formulated to contain 1.35%, 1.55%, and 1.75% SID Arg. All pigs received a common diet from d20 to d41. Data were analyzed by pen as repeated measures (SAS 9.4). No interaction between water- and dietary-Arg was detected on nursery pig growth performance. There was a significant quadratic effect of SID Arg in the feed on pig final body weight (BW), ADG, ADFI, and G:F (P ≤ 0.037), where feeding 1.55% dietary Arg tended to improve growth performance compared to the 1.35% level for the 41 d of the trial (P ≤ 0.088). The use of the stock 8% Arg in the water resulted in a reduction in crypt depth (0:132.5, 4:140.7, 8:117.3, 12:132.0; P ≤ 0.01) and an improvement in intestinal permeability. The 4% oral Arg significantly reduced villous height:crypt depth ratio (0:2.50, 4:2.09, 8:2.56, 12:2.43; P ≤ 0.02). In conclusion, the feeding of 1.55% Arg resulted in an improvement in nursery pig ADG, ADFI, G:F, and final BW but did not alter intestinal villi morphology; however, the use of Arg in the water resulted in an improvement in intestinal villi, but no phenotypical change in piglet growth in the nursery.

The biological activity and signaling profile of EGF/EGFR were affected under heat stress conditions in IEC6 cells

Epidermal growth factor (EGF) is an effective cytoprotective peptide. It is the main nutritional factor involved in the development of the intestinal tract. It has many important biological effects on the intestinal mucosa. After binding to epidermal growth factor receptor (EGFR), it initiates a signal transduction cascade to jointly promote the migration, proliferation, and differentiation of various cell types. Heat stress severely affects the intestinal health of livestock and is becoming increasingly prevalent due to the yearly increase in ambient temperature and intestinal diseases. However, the effect of heat stress on the activity and signaling of EGF/EGFR in intestinal cells is still unclear. Therefore, rat intestinal crypt epithelial cell line (IEC6) was used as a model to explore this issue, and the results showed that EGF/EGFR is internalized into IEC6 cells in a time-dependent manner under physiological conditions. However, the activity of EGF/EGFR was altered under heat stress. Furthermore, we explored the effect of heat stress on EGF/EGFR-activated signaling transduction in IEC6 cells, and the results showed that levels of factors involved in EGFR-mediated intracellular signaling (such as EGFR, signal transducers and activators of transcription 3/protein kinase B, and extracellular regulatory kinase 1/2) were downregulated under heat stress. In summary, this study shows that heat stress could damage the biological activity and intracellular signaling of EGF/EGFR. These findings have scientific importance in the field of animal husbandry; and lay the foundation for the further study of the biological activities of EGF/EGFR in the intestine.

Dietary L-citrulline modulates the growth performance, amino acid profile, and the growth hormone/insulin-like growth factor axis in broilers exposed to high temperature

Heat stress adversely affects the growth performance, muscle development, and protein metabolism in poultry. l-Citrulline (L-Cit), is a non-essential amino acid that is known to stimulate muscle protein synthesis under stress conditions. This study investigated whether L-Cit could influence the growth performance, amino acid profile, and protein metabolism in broilers exposed to high ambient temperature. In a 2 × 2 factorial arrangement, Arbor acre broilers (288 chickens) were fed with basal diet (CON) or 1% L-Cit supplemented diet and later subjected to either thermoneutral (TNZ: 24°C, 24 h/d) or heat stress (HS: 35°C for 8 h/d) environment for 21 days. The results showed that L-Cit diet promoted the body weight and body weight gain of broilers higher than the CON diet, and it further alleviated HS suppression of body weight and feed intake at certain periods (p &lt; 0.05). Plasma urea, uric acid, glucose, and total cholesterol were elevated during HS, whereas, the triglyceride content was decreased (p &lt; 0.05). Serum amino acids including citrulline, alanine, aspartate, and taurine were decreased by HS. L-Cit supplementation restored the citrulline level and alleviated HS induction of 3-methylhistidine (p &lt; 0.05). L-Cit supplementation increased the plasma growth hormone (GH) and insulin-like growth factor-1 (IGF-1) concentration, as well as the GH concentration in the breast muscle (p &lt; 0.05). The mRNA expression showed that HS elicited tissue-specific responses by upregulating some growth factors in the breast muscle, but downregulated the GH receptor, GH binding protein, and IGF-1 expression in the hypothalamus. L-Cit supplementation upregulated the GHRH and IGFBP2 expression in the hypothalamus. L-Cit also upregulated the expression of IGF-1R and IGFBP2 in the breast muscle of HS broilers. The total mTOR protein level in the breast muscle of HS broilers was also increased by L-Cit diet (p &lt; 0.05). Therefore, this study demonstrated that HS negatively affected the growth performance of broilers and dysregulated the expression of growth factors related to protein metabolism. Contrarily, L-Cit promoted the growth responses of broilers via its stimulation of circulating GH/IGF-1 concentration. To certain extents, L-Cit supplementation elicited protective effects on the growth performance of HS broilers by diminishing protein catabolism.

Nutritional Supplements to Improve Outcomes in Preterm Neonates

Preterm infants are at higher risk of mortality and morbidity compared with those born at term. Nutrition-related morbidities include poor growth, immune deficiency, nutritional deficiencies, and adverse long-term neurodevelopment. In addition to macronutrients, many nutritional supplements have been used to enhance growth and development, and decrease infections. Nutrients can enhance preterm infants' immune status, optimize the microbiome, improve growth and development, and influence the risk of necrotizing enterocolitis, sepsis, and other outcomes.

Untargeted Metabolomics Sensitively Differentiates Gut Bacterial Species in Single Culture and Co-Culture Systems

Gut microbiome plays a vital role in human health, and its characteristic has been widely identified through next-generation sequencing techniques. Although with great genomic insights into gut microbiome, its functional information is not clearly elaborated through metagenomic techniques. On the other hand, it is suggested that fecal metabolome can be used as a functional readout of the microbiome composition; therefore, we designed a proof-of-concept study to first characterize the metabolome of different gut microbes and then investigate the relationship between bacterial metabolomes and their compositions in co-culture systems. We selected eight representative bacteria species from Bifidobacterium (2), Bacteroides (1), Lactobacillus (4), and Akkermansia (1) genera as our model microbes. Liquid chromatography coupled mass spectrometry-based untargeted metabolomics was utilized to explore the microbial metabolome of bacteria single cultures and co-culture systems. Through spectral comparisons, our results showed that untargeted metabolomics could capture the similarity and differences in metabolic profiles from eight representative gut bacteria. Also, untargeted metabolomics could sensitively differentiate gut bacterial species based on our statistical analyses. For example, citrulline and histamine levels were significantly different among four Lactobacillus species. In addition, in the co-culture systems with different bacteria population ratios, gut bacterial metabolomes can be used to quantitatively reflect bacterial population in a mixed culture. For instance, the relative abundance of 2-hydroxybutyric acid changed proportionately with the changed population ratio of Lactobacillus reuteri in the co-culture system. In summary, we proposed a workflow that could demonstrate the capability of untargeted metabolomics in differentiating gut bacterial species and detecting their characteristic metabolites proportionally to the microbial population in co-culture systems.

Spermine protects intestinal barrier integrity through ras-related C3 botulinum toxin substrate 1/phospholipase C-γ1 signaling pathway in piglets

Weaning stress can cause tight junctions damage and intestinal permeability enhancement, which leads to intestinal imbalance and growth retardation, thereby causing damage to piglet growth and development. Spermine can reduce stress. However, the mechanism of spermine modulating the intestinal integrity in pigs remains largely unknown. This study aims to examine whether spermine protects the intestinal barrier integrity of piglets through ras-related C3 botulinum toxin substrate 1 (Rac1)/phospholipase C-γ1 (PLC-γ1) signaling pathway. In vivo, 80 piglets were categorised into 4 control groups and 4 spermine groups (10 piglets per group). The piglets were fed with normal saline or spermine at 0.4 mmol/kg BW for 7 h and 3, 6 and 9 d. In vitro, we investigated whether spermine protects the intestinal barrier after a tumor necrosis factor α (TNF-α) challenge through Rac1/PLC-γ1 signaling pathway. The in vivo study found that spermine supplementation increased tight junction protein mRNA levels and Rac1/PLC-γ1 signaling pathway gene expression in the jejunum of piglets. The serum D-lactate content was significantly decreased after spermine supplementation (P < 0.05). The in vitro study found that 0.1 μmol/L spermine increased the levels of tight junction protein expression, Rac1/PLC-γ1 signaling pathway and transepithelial electrical resistance, and decreased paracellular permeability (P < 0.05). Further experiments demonstrated that spermine supplementation enhanced the levels of tight junction protein expression, Rac1/PLC-γ1 signaling pathway and transepithelial electrical resistance, and decreased paracellular permeability compared with the NSC-23766 and U73122 treatment with spermine after TNF-α challenge (P < 0.05). Collectively, spermine protects intestinal barrier integrity through Rac1/PLC-γ1 signaling pathway in piglets.

Present and Future Therapeutic Approaches to Barrier Dysfunction

There is converging and increasing evidence, but also uncertainty, for the role of abnormal intestinal epithelial barrier function in the origin and development of a growing number of human gastrointestinal and extraintestinal inflammatory disorders, and their related complaints. Despite a vast literature addressing factors and mechanisms underlying changes in intestinal permeability in humans, and its connection to the appearance and severity of clinical symptoms, the ultimate link remains to be established in many cases. Accordingly, there are no directives or clinical guidelines related to the therapeutic management of intestinal permeability disorders that allow health professionals involved in the management of these patients to carry out a consensus treatment based on clinical evidence. Instead, there are multiple pseudoscientific approaches and commercial propaganda scattered on the internet that confuse those affected and health professionals and that often lack scientific rigor. Therefore, in this review we aim to shed light on the different therapeutic options, which include, among others, dietary management, nutraceuticals and medical devices, microbiota and drugs, and epigenetic and exosomes-manipulation, through an objective evaluation of the scientific publications in this field. Advances in the knowledge and management of intestinal permeability will sure enable better options of dealing with this group of common disorders to enhance quality of life of those affected.

Potential Implications of Citrulline and Quercetin on Gut Functioning of Monogastric Animals and Humans: A Comprehensive Review

The importance of gut health in animal welfare and wellbeing is undisputable. The intestinal microbiota plays an essential role in the metabolic, nutritional, physiological, and immunological processes of animals. Therefore, the rapid development of dietary supplements to improve gut functions and homeostasis is imminent. Recent studies have uncovered the beneficial effects of dietary supplements on the immune response, microbiota, gut homeostasis, and intestinal health. The application of citrulline (a functional gut biomarker) and quercetin (a known potent flavonoid) to promote gut functions has gained considerable interest as both bioactive substances possess anti-inflammatory, anti-oxidative, and immunomodulatory properties. Research has demonstrated that both citrulline and quercetin can mediate gut activities by combating disruptions to the intestinal integrity and alterations to the gut microbiota. In addition, citrulline and quercetin play crucial roles in maintaining intestinal immune tolerance and gut health. However, the synergistic benefits which these dietary supplements (citrulline and quercetin) may afford to simultaneously promote gut functions remain to be explored. Therefore, this review summarizes the modulatory effects of citrulline and quercetin on the intestinal integrity and gut microbiota, and further expounds on their potential synergistic roles to attenuate intestinal inflammation and promote gut health.

Effects of dietary components on intestinal permeability in health and disease

Altered intestinal permeability plays a role in many pathological conditions. Intestinal permeability is a component of the intestinal barrier. This barrier is a dynamic interface between the body and the food and pathogens that enter the gastrointestinal tract. Therefore, dietary components can directly affect this interface, and many metabolites produced by the host enzymes or the gut microbiota can act as signaling molecules or exert direct effects on this barrier. Our aim was to examine the effects of diet components on the intestinal barrier in health and disease states. Herein, we conducted an in-depth PubMed search based on specific key words (diet, permeability, barrier, health, disease, and disorder), as well as cross references from those articles. The normal intestinal barrier consists of multiple components in the lumen, epithelial cell layer and the lamina propria. Diverse methods are available to measure intestinal permeability. We focus predominantly on human in vivo studies, and the literature is reviewed to identify dietary factors that decrease (e.g., emulsifiers, surfactants, and alcohol) or increase (e.g., fiber, short-chain fatty acids, glutamine, and vitamin D) barrier integrity. Effects of these dietary items in disease states, such as metabolic syndrome, liver disease, or colitis are documented as examples of barrier dysfunction in the multifactorial diseases. Effects of diet on intestinal barrier function are associated with precise mechanisms in some instances; further research of those mechanisms has potential to clarify the role of dietary interventions in treating diverse pathologic states.

Nanocurcumin and arginine entrapped injectable chitosan hydrogel for restoration of hypoxia induced endothelial dysfunction

Hypoxia is a condition that gradually leads to ischemic damages in organs which is marked by poor tissue perfusion. Depending on the severity of the condition, revascularisation therapies are needed for reducing the risk of organ dysfunction. This study was aimed at developing an injectable nanocurcumin and arginine incorporated chitosan hydrogel (nC/R) that can prevent hypoxia induced endothelial damage. The prepared hydrogel has shear thinning, stable and injectable nature. The (nC and nC/R) hydrogels showed significant antioxidant activity and biodegradation in vitro. The release of curucmin and arginine from the nC/R was found to be higher at acidic pH, which predominates in an ischemic site. To mimic low oxygen environment, an in vitro hypoxic endothelial dysfunction model was developed which showed decreased expressions of phosphorylated eNOS (serine 1177) when compared to the cells cultured in normoxic condition. In vitro tube formation assay demonstrated the protective effect of nC/R towards hypoxia induced reduction of tube width. The nC/R hydrogel was found to enhance phosphorylation of eNOS at serine 1177 site in cultured endothelial cells subjected to hypoxia. Therefore, nC/R hydrogel could effectively deliver both curcumin and arginine and therapeutically reduce the effect of hypoxia induced endothelial dysfunction.

l-Arginine Inhibits Apoptosis of Ovine Intestinal Epithelial Cells through the l-Arginine-Nitric Oxide Pathway

BACKGROUND

In nonruminants, many of the biological roles of l-arginine (Arg) at the intestinal level are mediated through the Arg-nitric oxide (Arg-NO) pathway. Whether the Arg-NO pathway is involved in controlling the immune response and viability in ovine intestinal epithelial cells (IOECs) is unclear.

OBJECTIVES

The current study aimed to examine the role of the Arg-NO pathway in apoptosis, antioxidant capacity, and mitochondrial function of IOECs.

METHODS

The IOECs were incubated in Arg-free DMEM supplemented with 150 μM Arg (CON) or 300 μM Arg (ARG) alone or with 350 μM Nw-nitro-l-arginine methyl ester hydrochloride (l-NAME) (CON + NAME, ARG + NAME) for 24 h. The reactive oxygen species (ROS) concentration, antioxidant capacity, and cell apoptotic percentage were determined.

RESULTS

Arg supplementation decreased (P < 0.05) the ROS concentration (38.9% and 22.7%) and apoptotic cell percentage (57.2% and 54.8%) relative to the CON and CON + NAME groups, respectively. Relative to the CON and ARG treatments, the l-NAME administration decreased (P < 0.05) the mRNA abundance of superoxide dismutase 2 (32% and 21.3%, respectively) and epithelial NO synthase (36% and 29.1%, respectively). Arg supplementation decreased (P < 0.05) the protein abundance of apoptosis antigen 1 (FAS) (52.0% and 43.9%) but increased (P < 0.05) those of nuclear respiratory factor 1 (31.3% and 22.9%) and inducible NO synthase (35.2% and 41.8%) relative to the CON and CON + NAME groups, respectively.

CONCLUSIONS

The inhibition of apoptosis in IOECs due to the increased supply of Arg is associated with the mitochondria- and FAS-dependent pathways through the activity of the Arg-NO pathway. The findings help elucidate the role of the Arg-NO pathway in IOEC growth and apoptosis.

Metabolic studies reveal that ruminal microbes of adult steers do not degrade rumen-protected or unprotected L-citrulline

In vitro and in vivo experiments were conducted to determine the metabolism of rumen-protected or unprotected l-citrulline (Cit) plus l-glutamine (Gln) by ruminal microbes. In the in vitro experiment, whole ruminal fluid (3 mL, containing microorganisms) from steers was incubated at 37 ºC with 5 mM Cit plus 6 mM Gln (in a rumen-protected or unprotected form) for 0, 0.5, 2, or 4 h after which times 50 µL samples were collected for AA and ammonia analyses. In the in vivo experiment, at 0.5 h before and 0, 0.5, 1, 2, 4, and 6 h after cannulated adult steers consumed 0.56 kg dried-distillers' grain mixed with 70 g Cit plus 70 g Gln (in a rumen-protected or unprotected form), samples of ruminal fluid and jugular venous blood were obtained for AA analyses. Results from both in vitro and in vivo experiments demonstrated extensive hydrolysis of rumen-unprotected Gln into glutamate, but little degradation of the rumen-protected Gln or rumen-protected and unprotected Cit by ruminal microbes. Concentrations of Cit and arginine in the plasma of steers consuming rumen-protected or unprotected AA increased at 1 and 2 h after the meal, respectively, when compared with values at 0 h. Collectively, these novel findings indicate that ruminal microbes of adult steers do not degrade extracellular Cit in a rumen-protected or unprotected form. Our results refute the view that all dietary AAs are extensively catabolized by ruminal microorganisms and also have important implications for dietary supplementation with Cit to ruminants to enhance the concentration of arginine in their plasma and their productivity.

Intestinal Permeability, Inflammation and the Role of Nutrients

The interaction between host and external environment mainly occurs in the gastrointestinal tract, where the mucosal barrier has a critical role in many physiologic functions ranging from digestion, absorption, and metabolism. This barrier allows the passage and absorption of nutrients, but at the same time, it must regulate the contact between luminal antigens and the immune system, confining undesirable products to the lumen. Diet is an important regulator of the mucosal barrier, and the cross-talk among dietary factors, the immune system, and microbiota is crucial for the modulation of intestinal permeability and for the maintenance of gastrointestinal tract (GI) homeostasis. In the present review, we will discuss the role of a number of dietary nutrients that have been proposed as regulators of inflammation and epithelial barrier function. We will also consider the metabolic function of the microbiota, which is capable of elaborating the diverse nutrients and synthesizing products of great interest. Better knowledge of the influence of dietary nutrients on inflammation and barrier function can be important for the future development of new therapeutic approaches for patients with mucosal barrier dysfunction, a critical factor in the pathogenesis of many GI and non-GI diseases.

Beyond Heat Stress: Intestinal Integrity Disruption and Mechanism-Based Intervention Strategies

The current climate changes have increased the prevalence and intensity of heat stress (HS) conditions. One of the initial consequences of HS is the impairment of the intestinal epithelial barrier integrity due to hyperthermia and hypoxia following blood repartition, which often results in a leaky gut followed by penetration and transfer of luminal antigens, endotoxins, and pathogenic bacteria. Under extreme conditions, HS may culminate in the onset of “heat stroke”, a potential lethal condition if remaining untreated. HS-induced alterations of the gastrointestinal epithelium, which is associated with a leaky gut, are due to cellular oxidative stress, disruption of intestinal integrity, and increased production of pro-inflammatory cytokines. This review summarizes the possible resilience mechanisms based on in vitro and in vivo data and the potential interventions with a group of nutritional supplements, which may increase the resilience to HS-induced intestinal integrity disruption and maintain intestinal homeostasis.

The protective effects of enriched citrulline fermented milk with Lactobacillus helveticus on the intestinal epithelium integrity against Escherichia coli infection

This study examined the protective effects of citrulline enriched-fermented milk with live Lactobacillus helveticus ASCC 511 (LH511) on intestinal epithelial barrier function and inflammatory response in IPEC-J2 cells caused by pathogenic Escherichia coli. Five percent (v/v) of fermented milk with live LH511 and 4 mM citrulline (5%LHFM_Cit-4mM) significantly stimulated the population of IPEC-J2 cells by 36% as determined by MTT assay. Adhesion level of LH511 was significantly increased by 9.2% when incubated with 5%LHFM_Cit-4mM and 5%LHFM_Cit-4mM reduced the adhesion of enterohemorrhagic (EHEC) and entero-invasive (EIEC) E. coli in IPEC-J2 cells by 35.79% and 42.74%, respectively. Treatment with 5%LHFM_Cit-4mM ameliorated lipopolysaccharide (LPS) from E. coli O55:B5 induced activated inflammatory cytokines expression (TNF-α, IL-6 and IL-8) and concentration (IL-6 and IL-8) and early apoptosis. It restored the transepithelial electrical resistance (TEER) and regulated the expression and distribution of tight junction (TJ) proteins (zonula occluden-1 (ZO-1), occludin and claudin-1), toll-like receptors (TLRs) (TLR2 and TLR4) and negative regulators of TLRs signalling pathway (A20 and IRAK-M). In conclusion, our findings suggested that 5%LHFM_Cit-4mM might have the positive effects on improving and maintaining the intestinal epithelial cell integrity and inflammatory response under both normal and pathogenic LPS-stimulated conditions.

Tight Junction Proteins in the Weaned Piglet Intestine: Roles and Regulation

The intestinal epithelial barrier plays a crucial role in the health and growth of weaned piglets. Proper epithelial function mainly depends on tight junctions (TJs), which act as both ion channels and a barrier against noxious molecules. TJs are multiprotein complexes consisting of transmembrane and membrane-associated proteins. Because the intestine in piglets is immature and incomplete, its structure and function are easily impaired by various stresses, infections, and food-related factors. Certain nutrients have been demonstrated to participate in intestinal TJ regulation. Probiotics, amino acids, fibers, oligosaccharide, and certain micronutrients can enhance barrier integrity and counteract infections through elevated TJ protein expression and distribution. In this review, the distribution and classification of intestinal TJs is described, the factors influencing TJs after weaning are summarized, and the regulation of weaning piglet intestinal TJs by nutrients is discussed.

Lactobacillus reuteri DSM 17938 feeding of healthy newborn mice regulates immune responses while modulating gut microbiota and boosting beneficial metabolites

Early administration of Lactobacillus reuteri DSM 17938 (LR) prevents necrotizing enterocolitis and inhibits regulatory T-cell (Treg)-deficiency-associated autoimmunity in mice. In humans, LR reduces crying time in breastfed infants with colic, modifies severity in infants with acute diarrheal illnesses, and improves pain in children with functional bowel disorders. In healthy breastfed newborns with evolving microbial colonization, it is unclear if early administration of LR can modulate gut microbiota and their metabolites in such a way as to promote homeostasis. We gavaged LR (107 colony-forming units/day, daily) to C57BL/6J mice at age of day 8 for 2 wk. Both male and female mice were investigated in these experiments. We found that feeding LR did not affect clinical phenotype or inflammatory biomarkers in plasma and stool, but LR increased the proportion of Foxp3+ regulatory T cells (Tregs) in the intestine. LR also increased bacterial diversity and the relative abundance of p_Firmicutes, f_Lachnospiraceae, f_Ruminococcaceae, and genera Clostridium and Candidatus arthromitus, while decreasing the relative abundance of p_Bacteriodetes, f_Bacteroidaceae, f_Verrucomicrobiaceae, and genera Bacteroides, Ruminococcus, Akkermansia, and Sutterella. Finally, LR exerted a major impact on the plasma metabolome, upregulating amino acid metabolites formed via the urea, tricarboxylic acid, and methionine cycles and increasing tryptophan metabolism. In conclusion, early oral administration of LR to healthy breastfed mice led to microbial and metabolic changes which could be beneficial to general health.NEW & NOTEWORTHY Oral administration of Lactobacillus reuteri DSM 17938 (LR) to healthy breastfed mice promotes intestinal immune tolerance and is linked to proliferation of beneficial gut microbiota. LR upregulates plasma metabolites that are involved in the urea cycle, the TCA cycle, methionine methylation, and the polyamine pathway. Herein, we show that LR given to newborn mice specifically increases levels of tryptophan metabolites and the purine nucleoside adenosine that are known to enhance tolerance to inflammatory stimuli.

Protective effects of L-arginine on the intestinal epithelial barrier under heat stress conditions in rats and IEC-6 cell line

Heat stress (HS) and the associated restricted blood flow to the intestine have been proven to destroy intestinal integrity. Considering the beneficial properties of L-arginine on gut function, we investigated the protective effects of L-arginine on the intestine under HS conditions. In vivo, the serum cortisol level and the rectal temperature increased in response to HS. Under HS, the intestinal damage showed obvious morphological changes. Furthermore, HS decreased the mRNA and protein expression levels of Nurr1, ZO-1, occludin, claudin-6 and E-cadherin, increased the mRNA expression of NF-κB and IL-1β, and increased the protein expression of cleaved caspase-3. In contrast, L-arginine supplementation maintained intestinal integrity and increased the villus/crypt ratio. L-arginine also suppressed the expression of inflammation-related genes and the protein expression of cleaved caspase-3, whereas it upregulated the mRNA and protein expression of tight junction proteins and LC3B protein expression. In vitro, L-arginine attenuated HS-induced apoptosis as demonstrated by flow cytometry and decreased cleaved caspase-3 protein expression. L-arginine induced autophagy, which was demonstrated by decreased expression of p62 and p-mTOR/mTOR, and increased expression of LC3B. The protein expression levels of TJ proteins also enhanced by L-arginine in IEC-6 cells. Taken together, these results suggest that L-arginine can alleviate intestinal damage and protect the intestinal integrity by suppressing local inflammation response, promoting the production of TJs and facilitating autophagy under HS conditions.

Human Breast Milk Promotes the Secretion of Potentially Beneficial Metabolites by Probiotic Lactobacillus reuteri DSM 17938

Human breast milk (HBM) may have beneficial effects on Lactobacillus reuteri DSM 17938 (LR 17938) -mediated immunomodulation. We aimed to determine the effects of HBM on proliferation of LR 17938 in vitro and its associated proteins and metabolites in culture, in order to provide mechanistic insights into the health benefits of LR 17938. LR 17938 was cultured anaerobically in MRS bacterial culture media, HBM (from 6 mothers), and 2 types of cow-milk formula. The colony-forming unit (CFU) was calculated to evaluate LR 17938 growth. Sixteen-hour-fermented supernatants were used for metabolomics, and bacterial lysates were used for proteomics analysis. We found that growth of LR 17938 was 10 times better in HBM than in formula. We detected 261/452 metabolites upregulated when LR 17938 cultured in HBM compared to in formula, mainly participating in the glyoxylate cycle (succinate), urea cycle (citrulline), methionine methylation (N-acetylcysteine), and polyamine synthesis (spermidine). The significantly up-regulated enzymes were also involved in the formation of acetyl-CoA in the glyoxylate cycle and the antioxidant N-acetylcysteine. In conclusion, HBM enhances the growth of LR 17938 compared to formula and promotes LR 17938-associated metabolites that relate to energy and antioxidant status, which may be linked to the physiological effects of L. reuteri.

Substantial Extracellular Metabolic Differences Found Between Phylogenetically Closely Related Probiotic and Pathogenic Strains of Escherichia coli

Since its first isolation a century ago, the gut inhabitant Escherichia coli strain Nissle 1917 has been shown to have probiotic activities; however, it is yet not fully elucidated which differential factors play key roles in its beneficial interactions with the host. To date, no metabolomics studies have been reported investigating the potential role of small molecules in functional strain differentiation of Nissle from its genetically close neighbors. Here, we present results of liquid chromatography coupled to high-resolution mass spectrometry characterization of extracellular metabolomes of E. coli strains as a proxy of their bioactivity potential. We found that phylogroup B2 strains exported a more diverse arsenal of metabolites than strains of other phylogroups. Zooming into the phylogroup B2 metabolome identified consistent substantial differences between metabolic output of E. coli Nissle and other strains, particularly in metabolites associated to the Argimine biosynthesis pathway. Nissle was found to release higher levels of Ornithine and Citrulline whilst depleting greater amounts of Arginine from the medium. Moreover, a novel Nissle-specific metabolite not reported before in bacteria, 5-(Carbamoylamino)-2-hydroxypentanoic acid (Citrulline/Arginic Acid related) was observed. Finally, Nissle, CFT073 and NCTC12241/ATCC25922 shared the excretion of N5-Acetylornithine, whereas other strains released N2-Acetylornithine or no N-Acetylornithine at all. Thus, we found substantial metabolic differences in phylogenetically very similar E. coli strains, an observation which suggests that it is justified to further investigate roles of small molecules as potential modulators of the gut environment by probiotic, commensal, and pathogenic strains, including E. coli Nissle 1917.

Pathophysiology of Necrotizing Enterocolitis: An Update

NEC is a devastating disease that, once present, is very difficult to treat. In the absence of an etiologic treatment, preventive measures are required. Advances in decoding the pathophysiology of NEC are being made but a more comprehensive understanding is needed for the targeting of preventative strategies. A better definition of the disease as well as diagnostic criteria are needed to be able to specifically label a disease as NEC. Multiple environmental factors combined with host susceptibility appear to contribute to enhanced risks for developing this disease. Several different proximal pathways are involved, all leading to a common undesired outcome: Intestinal necrosis. The most common form of this disease appears to involve inflammatory pathways that are closely meshed with the intestinal microbiota, where a dysbiosis may result in dysregulated inflammation. The organisms present in the intestinal tract prior to the onset of NEC along with their diversity and functional capabilities are just beginning to be understood. Fulfillment of postulates that support causality for particular microorganisms is needed if bacteriotherapies are to be intelligently applied for the prevention of NEC. Identification of molecular effector pathways that propagate inflammation, understanding of, even incipient role of genetic predisposition and of miRNAs may help solve the puzzle of this disease and may bring the researchers closer to finding a treatment. Despite recent progress, multiple limitations of the current animal models, difficulties related to studies in humans, along with the lack of a "clear" definition will continue to make it a very challenging disease to decipher.

Dietary supplementation with an amino acid blend enhances intestinal function in piglets

The traditionally classified nutritionally non-essential amino acids are now known to be insufficiently synthesized for maximal growth and optimal health in piglets. This study determined the effects of dietary supplementation with an amino acid blend (AAB; glutamate:glutamine:glycine:arginine:N-acetylcysteine = 5:2:2:1:0.5) on piglet growth performance and intestinal functions. Sixteen piglets (24-day-old) were randomly assigned to a corn and soybean meal-based diet supplemented with 0.99% alanine (isonitrogenous control) or 1% AAB. On day 20 of the trial, blood and intestinal tissue samples were obtained from piglets. Compared with the control, AAB supplementation reduced (P < 0.05) diarrhoea incidence; plasma alanine aminotransferase and diamine oxidase activities; intestinal concentrations of hydrogen peroxide, malondialdehyde, and heat shock protein-70, and intestinal mRNA levels for interleukin-1β, interferon-γ, and chemokine (C-X-C motif) ligand-9; and the numbers of Enterobacterium family, Enterococcus genus and Clostridium coccoides in the colon digesta. Furthermore, AAB supplementation enhanced (P < 0.05): the plasma concentrations of serine, aspartate, glutamate, cysteine, tyrosine, phenylalanine, tryptophan, lysine, arginine, citrulline, ornithine, taurine, and γ-aminobutyric acid; intestinal villus height and surface area, villus height/crypt depth ratio, antioxidative enzyme activities, and mRNA levels for porcine β-defensin-1, sodium-independent amino acid transporters (b^0,+AT and y⁺LAT1), aquaporin (AQP) 3, AQP8, AQP10, nuclear factor erythroid 2-related factor 2 and glutathione S-transferase omega-2, and protein abundances of AQP3, AQP4, claudin-1, occludin and myxovirus resistance 1; and the numbers of Bifidobacterium genus and Lactobacillus genus in the colon digesta. Collectively, these comprehensive results indicate that dietary AAB supplementation plays an important role in improving piglet growth and intestinal function.

Regulation of Intestinal Epithelial Cells Properties and Functions by Amino Acids

Intestinal epithelial cells (IECs) line the surface of intestinal epithelium, where they play important roles in the digestion of food, absorption of nutrients, and protection of the human body from microbial infections, and others. Dysfunction of IECs can cause diseases. The development, maintenance, and functions of IECs are strongly influenced by external nutrition, such as amino acids. Amino acids play important roles in regulating the properties and functions of IECs. In this article, we briefly reviewed the current understanding of the roles of amino acids in the regulation of IECs' properties and functions in physiological state, including in IECs homeostasis (differentiation, proliferation, and renewal), in intestinal epithelial barrier structure and functions, and in immune responses. We also summarized some important findings on the effects of amino acids supplementation (e.g., glutamine and arginine) in restoring IECs' and intestine functions in some diseased states. These findings will further our understanding of the important roles of amino acids in the homeostasis of IECs and could potentially help identify novel targets and reagents for the therapeutic interventions of diseases associated with dysfunctional IECs.

Oral arginine supplementation protects female mice from the onset of non-alcoholic steatohepatitis

Dietary arginine (Arg) supplementation has been proposed to have positive effects on the development of liver diseases. In the present study, we investigate if an oral Arg supplementation in diet protects mice fed a fructose, fat and cholesterol enriched Western-style diet (WSD) from the development of non-alcoholic steatohepatitis (NASH). Female C57BL/6J mice were fed a liquid control diet or a liquid WSD ± Arg (2.49 g/kg body weight/day) for 6 weeks. Indices of liver injury, glucose metabolism and intestinal permeability were determined. While Arg supplementation had no effects on body weight gain, fasting blood glucose levels were significantly lower in WSD+Arg-fed mice than in C+Arg-fed animals. WSD-fed mice developed liver steatosis accompanied with inflammation, both being significantly attenuated in WSD+Arg-fed mice. These effects of Arg supplementation went along with a protection against WSD-induced decreased tight junction protein levels in the upper parts of the small intestine, increased levels of bacterial endotoxin in portal plasma as well as increased hepatic toll-like receptor-4 mRNA and 4-hydroxynonenal protein adduct levels. In conclusion, Arg supplementation may protect mice from the development of NASH.

The nitric oxide synthase 2 pathway is targeted by both pro- and anti-inflammatory treatments in the immature human intestine

BACKGROUND AND AIM

NO synthase 2 (NOS2) was recently identified as one the most overexpressed genes in intestinal samples of premature infants with necrotizing enterocolitis (NEC). NOS2 is widely implicated in the processes of epithelial cell injury/apoptosis and host immune defense but its specific role in inflammation of the immature human intestinal mucosa remains unclear. Interestingly, factors that prevent NEC such as epidermal growth factor (EGF) attenuate the inflammatory response in the mid-gestation human small intestine using serum-free organ culture while drugs that are associated with NEC occurrence such as the non-steroidal anti-inflammatory drug, indomethacin (INDO), exert multiple detrimental effects on the immature human intestine. In this study we investigate the potential role of NOS2 in modulating the gut inflammatory response under protective and stressful conditions by determining the expression profile of NOS2 and its downstream pathways in the immature intestine.

METHODS

Gene expression profiles of cultured mid-gestation human intestinal explants were investigated in the absence or presence of a physiological concentration of EGF (50 ng/ml) or 1 μM INDO for 48 h using Illumina whole genome microarrays, Ingenuity Pathway Analysis software and quantitative PCR to investigate the expression of NOS2 and NOS2-pathway related genes.

RESULTS

In the immature intestine, NOS2 expression was found to be increased by EGF and repressed by INDO. Bioinformatic analysis identified differentially regulated pathways where NOS2 is known to play an important role including citrulline/arginine metabolism, epithelial cell junctions and oxidative stress. At the individual gene level, we identified many differentially expressed genes of the citrulline/arginine metabolism pathway such as ARG1, ARG2, GLS, OAT and OTC in response to EGF and INDO. Gene expression of tight junction components such as CLDN1, CLDN2, CLDN7 and OCN and of antioxidant markers such as DUOX2, GPX2, SOD2 were also found to be differentially modulated by EGF and INDO.

CONCLUSION

These results suggest that the protective effect of EGF and the deleterious influence of INDO on the immature intestine could be mediated via regulation of NOS2. Pathways downstream of NOS2 involved with these effects include metabolism linked to NO production, epithelial barrier permeability and antioxidant expression. These results suggest that NOS2 is a likely regulator of the inflammatory response in the immature human gut and may provide a mechanistic basis for the protective effect of EGF and the deleterious effects of INDO.

Potential of single cationic amino acid molecule "Arginine" for stimulating oral absorption of insulin

We have reported that cell-penetrating peptides, such as oligoarginine, act as powerful absorption enhancers for the development of oral insulin delivery systems. However, the minimal essential sequence of oligoarginine that stimulates intestinal insulin absorption remains unclear. Therefore, the present study was conducted to clarify this minimum sequence of oligoarginine and to examine the effect of single cationic amino acid arginine on the intestinal and oral absorption of insulin. The results demonstrated that a remarkable enhancement of intestinal insulin absorption was observed after coadministration of insulin with l-arginine. The efficacy of d-forms of oligoarginine/arginine tended to decrease with a decreasing number of amino acid residues, whereas the effect of l-arginine was the strongest of any of the l-forms of oligoarginine/arginine. Interestingly, the effect of l-arginine was stronger than that of d-arginine at various concentrations, and the effect of other cationic amino acids such as lysine and histidine was relatively lower than that of arginine. In addition, no leakage of lactate dehydrogenase from the intestinal epithelium and no change in the transepithelial electrical resistance of a Caco-2 cell monolayer were detected after administration of l-arginine as the single amino acid, which suggests that there were no undesirable effects of arginine on the integrity of cell membranes and paracellular tight junctions. Oral administration study in mice demonstrated that the stronger hypoglycemic effects were observed after coadministration of insulin with l-arginine. In this study, we found that arginine is a key cationic amino acid for delivering insulin across intestinal epithelial barriers and hopefully accelerating the clinical development of oral insulin delivery systems.

Correlation between plasma levels of arginine and citrulline in preterm and full-term neonates: Therapeutical implications

BACKGROUND

Preterm neonates exhibit several deficiencies that endanger their lives. Understanding those disturbances will provide tools for the management of preterm neonates. The present work focuses on arginine and citrulline which has been flagged among the biochemical landmarks of prematurity.

METHODS

We examined blood samples of preterm newborns as compared with mature neonates to determine the levels of arginine and citrulline by capillary zone electrophoresis with laser induced fluorescence detection (CZE-LIFD).

RESULTS

Significantly lower levels of arginine and citrulline were found in preterm neonates than in mature neonates (P<.01). Interestingly there was a highly significant correlation between the two amino acids in mature neonates (P<.0001). Such correlation was present in preterm neonates too (P<.01). Pearson coefficient showed that 60% of the citrulline concentration depends on arginine concentration in mature neonates. Only 20% of the citrulline concentration depends on arginine concentration in preterm neonates. Although the ratio arginine/citrulline was lower in preterm neonates than in mature neonates the difference was not statistically significant.

CONCLUSIONS

These results suggest that less arginine is converted to citrulline to form nitric oxide in preterm than in full-term neonates. The result is discussed in terms of the immature enzymatic systems in the preterm neonate.

Oral citrulline supplementation protects female mice from the development of non-alcoholic fatty liver disease (NAFLD)

PURPOSE

Impairments of intestinal barrier function are discussed as risk factors for the development and progression of non-alcoholic fatty liver disease (NAFLD). Studies suggest an association between arginine/citrulline homeostasis and the development of liver damages. Here, the effect of an oral L-citrulline (Cit) supplement on the development of a Western-style diet (WSD)-induced NAFLD was determined in mice.

METHODS

Female 6- to 8-week-old C57BL/6J mice were either pair-fed a liquid Western-style or control diet (C) ± 2.5 g/kg bodyweight Cit for 6 weeks (C + Cit or WSD + Cit). Indices of liver damage, glucose metabolism, intestinal barrier function and NO synthesis were measured.

RESULTS

While bodyweight gain was similar between groups, markers of glucose metabolism like fasting blood glucose and HOMA index and markers of liver damage like hepatic triglyceride levels, number of neutrophils and plasminogen activator inhibitor-1 protein levels were significantly lower in WSD + Cit-fed mice when compared to WSD-fed mice only. Protein levels of the tight junction proteins occludin and zonula occludens-1 in duodenum were significantly lower in mice fed a WSD when compared to those fed a WSD + Cit (-~70 and -~60 %, respectively, P < 0.05), whereas portal endotoxin levels, concentration of 3-nitrotyrosine protein adducts in duodenum and toll-like receptor-4 mRNA expression in livers of WSD + Cit-fed mice were markedly lower than in WSD-fed mice (-~43 %, P = 0.056; -~80 and -~48 %, respectively, P < 0.05).

CONCLUSION

Our data suggest that the protective effects of supplementing Cit on the development of NAFLD in mice are associated with a decreased translocation of endotoxin into the portal vein.

Dysregulated expression of arginine metabolic enzymes in human intestinal tissues of necrotizing enterocolitis and response of CaCO2 cells to bacterial components

The small intestine is the exclusive site of arginine synthesis in neonates. Low levels of circulating arginine have been associated with the occurrence of necrotizing enterocolitis (NEC) but the mechanism of arginine dysregulation has not been fully elucidated. We aimed to investigate (i) expressional changes of arginine synthesizing and catabolic enzymes in human intestinal tissues of NEC, spontaneous intestinal perforation (SIP) and noninflammatory surgical conditions (Surg-CTL) and to investigate the (ii) mechanisms of arginine dysregulation and enterocyte proliferation upon stimulation by bacterial components, arginine depletion, ARG1 overexpression and nitric oxide (NO) supplementation. Our results showed that expressions of arginine synthesizing enzymes ALDH18A1, ASL, ASS1, CPS1, GLS, OAT and PRODH were significantly decreased in NEC compared with Surg-CTL or SIP tissues. Catabolic enzyme ARG1 was increased (>100-fold) in NEC tissues and histologically demonstrated to be expressed by infiltrating neutrophils. No change in arginine metabolic enzymes was observed between SIP and Surg-CTL tissues. In CaCO2 cells, arginine metabolic enzymes were differentially dysregulated by lipopolysaccharide or lipoteichoic acid. Depletion of arginine reduced cell proliferation and this phenomenon could be partially rescued by NO. Overexpression of ARG1 also reduced enterocyte proliferation. We provided the first expressional profile of arginine metabolic enzymes at the tissue level of NEC. Our findings suggested that arginine homeostasis was severely disturbed and could be triggered by inflammatory responses of enterocytes and infiltrating neutrophils as well as bacterial components. Such reactions could reduce arginine and NO, resulting in mucosal damage. The benefit of arginine supplementation for NEC prophylaxis merits further clinical evaluation.

Therapeutic and Prophylactic Potential of Morama (Tylosema esculentum): A Review

Tylosema esculentum (morama) is a highly valued traditional food and source of medicine for the San and other indigenous populations that inhabit the arid to semi-arid parts of Southern Africa. Morama beans are a rich source of phenolic acids, flavonoids, certain fatty acids, non-essential amino acids, certain phytosterols, tannins and minerals. The plant's tuber contains griffonilide, behenic acid and starch. Concoctions of extracts from morama bean, tuber and other local plants are frequently used to treat diarrhoea and digestive disorders by the San and other indigenous populations. Information on composition and bioactivity of phytochemical components of T. esculentum suggests that the polyphenol-rich extracts of the bean testae and cotyledons have great potential as sources of chemicals that inhibit infectious microorganisms (viral, bacterial and fungal, including drug-resistant strains), offer protection against certain non-communicable diseases and promote wound healing and gut health. The potential antinutritional properties of a few morama components are also highlighted. More research is necessary to reveal the full prophylactic and therapeutic potential of the plant against diseases of the current century. Research on domestication and conservation of the plant offers new hope for sustainable utilisation of the plant.

Improved cell line IPEC-J2, characterized as a model for porcine jejunal epithelium

Cell lines matching the source epithelium are indispensable for investigating porcine intestinal transport and barrier properties on a subcellular or molecular level and furthermore help to reduce animal usage. The porcine jejunal cell line IPEC-J2 is established as an in vitro model for porcine infection studies but exhibits atypically high transepithelial resistances (TER) and only low active transport rates so that the effect of nutritional factors cannot be reliably investigated. This study aimed to properly remodel IPEC-J2 and then to re-characterize these cells regarding epithelial architecture, expression of barrier-relevant tight junction (TJ) proteins, adequate TER and transport function, and reaction to secretagogues. For this, IPEC-J2 monolayers were cultured on permeable supports, either under conventional (fetal bovine serum, FBS) or species-specific (porcine serum, PS) conditions. Porcine jejunal mucosa was analyzed for comparison. Main results were that under PS conditions (IPEC-J2/PS), compared to conventional FBS culture (IPEC-J2/FBS), the cell height increased 6-fold while the cell diameter was reduced by 50%. The apical cell membrane of IPEC-J2/PS exhibited typical microvilli. Most importantly, PS caused a one order of magnitude reduction of TER and of trans- and paracellular resistance, and a 2-fold increase in secretory response to forskolin when compared to FBS condition. TJ ultrastructure and appearance of TJ proteins changed dramatically in IPEC-J2/PS. Most parameters measured under PS conditions were much closer to those of typical pig jejunocytes than ever reported since the cell line’s initial establishment in 1989. In conclusion, IPEC-J2, if cultured under defined species-specific conditions, forms a suitable model for investigating porcine paracellular intestinal barrier function.