Hydroxy-Selenomethionine, an Organic Selenium Source, Increases Selenoprotein Expression and Positively Modulates the Inflammatory Response of LPS-Stimulated Macrophages.

The role of 2-hydroxy-(4-methylseleno)butanoic acid (OH-SeMet), a form of organic selenium (Se), in selenoprotein synthesis and inflammatory response of THP1-derived macrophages stimulated with lipopolysaccharide (LPS) has been investigated. Glutathione peroxidase (GPX) activity, GPX1 gene expression, selenoprotein P (SELENOP) protein and gene expression, and reactive oxygen species (ROS) production were studied in Se-deprived conditions (6 and 24 h). Then, macrophages were supplemented with OH-SeMet for 72 h and GPX1 and SELENOP gene expression were determined. The protective effect of OH-SeMet against oxidative stress was studied in H2O2-stimulated macrophages, as well as the effect on GPX1 gene expression, oxidative stress, cytokine production (TNFα, IL-1ß and IL-10), and phagocytic and killing capacities after LPS stimulation. Se deprivation induced a reduction in GPX activity, GPX1 gene expression, and SELENOP protein and gene expression at 24 h. OH-SeMet upregulated GPX1 and SELENOP gene expression and decreased ROS production after H2O2 treatment. In LPS-stimulated macrophages, OH-SeMet upregulated GPX1 gene expression, enhanced phagocytic and killing capacities, and reduced ROS and cytokine production. Therefore, OH-SeMet supplementation supports selenoprotein expression and controls oxidative burst and cytokine production while enhancing phagocytic and killing capacities, modulating the inflammatory response, and avoiding the potentially toxic insult produced by highly activated macrophages.

Wasteosomes (corpora amylacea) of human brain can be phagocytosed and digested by macrophages.

BACKGROUND: Corpora amylacea of human brain, recently renamed as wasteosomes, are granular structures that appear during aging and also accumulate in specific areas of the brain in neurodegenerative conditions. Acting as waste containers, wasteosomes are formed by polyglucosan aggregates that entrap and isolate toxic and waste substances of different origins. They are expelled from the brain to the cerebrospinal fluid (CSF), and can be phagocytosed by macrophages. In the present study, we analyze the phagocytosis of wasteosomes and the mechanisms involved in this process. Accordingly, we purified wasteosomes from post-mortem extracted human CSF and incubated them with THP-1 macrophages. Immunofluorescence staining and time-lapse recording techniques were performed to evaluate the phagocytosis. We also immunostained human hippocampal sections to study possible interactions between wasteosomes and macrophages at central nervous system interfaces. RESULTS: We observed that the wasteosomes obtained from post-mortem extracted CSF are opsonized by MBL and the C3b complement protein. Moreover, we observed that CD206 and CD35 receptors may be involved in the phagocytosis of these wasteosomes by THP-1 macrophages. Once phagocytosed, wasteosomes become degraded and some of the resulting fractions can be exposed on the surface of macrophages and interchanged between different macrophages. However, brain tissue studies show that, in physiological conditions, CD206 but not CD35 receptors may be involved in the phagocytosis of wasteosomes. CONCLUSIONS: The present study indicates that macrophages have the machinery required to process and degrade wasteosomes, and that macrophages can interact in different ways with wasteosomes. In physiological conditions, the main mechanism involve CD206 receptors and M2 macrophages, which trigger the phagocytosis of wasteosomes without inducing inflammatory responses, thus avoiding tissue damage. However, altered wasteosomes like those obtained from post-mortem extracted CSF, which may exhibit waste elements, become opsonized by MBL and C3b, and so CD35 receptors constitute another possible mechanism of phagocytosis, leading in this case to inflammatory responses.

Frequency, risk factors, and outcomes of hospital readmissions of COVID-19 patients.

To determine the proportion of patients with COVID-19 who were readmitted to the hospital and the most common causes and the factors associated with readmission. Multicenter nationwide cohort study in Spain. Patients included in the study were admitted to 147 hospitals from March 1 to April 30, 2020. Readmission was defined as a new hospital admission during the 30 days after discharge. Emergency department visits after discharge were not considered readmission. During the study period 8392 patients were admitted to hospitals participating in the SEMI-COVID-19 network. 298 patients (4.2%) out of 7137 patients were readmitted after being discharged. 1541 (17.7%) died during the index admission and 35 died during hospital readmission (11.7%, p = 0.007). The median time from discharge to readmission was 7 days (IQR 3-15 days). The most frequent causes of hospital readmission were worsening of previous pneumonia (54%), bacterial infection (13%), venous thromboembolism (5%), and heart failure (5%). Age [odds ratio (OR): 1.02; 95% confident interval (95% CI): 1.01-1.03], age-adjusted Charlson comorbidity index score (OR: 1.13; 95% CI: 1.06-1.21), chronic obstructive pulmonary disease (OR: 1.84; 95% CI: 1.26-2.69), asthma (OR: 1.52; 95% CI: 1.04-2.22), hemoglobin level at admission (OR: 0.92; 95% CI: 0.86-0.99), ground-glass opacification at admission (OR: 0.86; 95% CI:0.76-0.98) and glucocorticoid treatment (OR: 1.29; 95% CI: 1.00-1.66) were independently associated with hospital readmission. The rate of readmission after hospital discharge for COVID-19 was low. Advanced age and comorbidity were associated with increased risk of readmission.

Risk Categories in COVID-19 Based on Degrees of Inflammation: Data on More Than 17,000 Patients from the Spanish SEMI-COVID-19 Registry.

(1) Background: The inflammation or cytokine storm that accompanies COVID-19 marks the prognosis. This study aimed to identify three risk categories based on inflammatory parameters on admission. (2) Methods: Retrospective cohort study of patients diagnosed with COVID-19, collected and followed-up from 1 March to 31 July 2020, from the nationwide Spanish SEMI-COVID-19 Registry. The three categories of low, intermediate, and high risk were determined by taking into consideration the terciles of the total lymphocyte count and the values of C-reactive protein, lactate dehydrogenase, ferritin, and D-dimer taken at the time of admission. (3) Results: A total of 17,122 patients were included in the study. The high-risk group was older (57.9 vs. 64.2 vs. 70.4 years; p < 0.001) and predominantly male (37.5% vs. 46.9% vs. 60.1%; p < 0.001). They had a higher degree of dependence in daily tasks prior to admission (moderate-severe dependency in 10.8% vs. 14.1% vs. 17%; p < 0.001), arterial hypertension (36.9% vs. 45.2% vs. 52.8%; p < 0.001), dyslipidemia (28.4% vs. 37% vs. 40.6%; p < 0.001), diabetes mellitus (11.9% vs. 17.1% vs. 20.5%; p < 0.001), ischemic heart disease (3.7% vs. 6.5% vs. 8.4%; p < 0.001), heart failure (3.4% vs. 5.2% vs. 7.6%; p < 0.001), liver disease (1.1% vs. 3% vs. 3.9%; p = 0.002), chronic renal failure (2.3% vs. 3.6% vs. 6.7%; p < 0.001), cancer (6.5% vs. 7.2% vs. 11.1%; p < 0.001), and chronic obstructive pulmonary disease (5.7% vs. 5.4% vs. 7.1%; p < 0.001). They presented more frequently with fever, dyspnea, and vomiting. These patients more frequently required high flow nasal cannula (3.1% vs. 4.4% vs. 9.7%; p < 0.001), non-invasive mechanical ventilation (0.9% vs. 3% vs. 6.3%; p < 0.001), invasive mechanical ventilation (0.6% vs. 2.7% vs. 8.7%; p < 0.001), and ICU admission (0.9% vs. 3.6% vs. 10.6%; p < 0.001), and had a higher percentage of in-hospital mortality (2.3% vs. 6.2% vs. 23.9%; p < 0.001). The three risk categories proved to be an independent risk factor in multivariate analyses. (4) Conclusion: The present study identifies three risk categories for the requirement of high flow nasal cannula, mechanical ventilation, ICU admission, and in-hospital mortality based on lymphopenia and inflammatory parameters.

Cyperus esculentus L. Tubers (Tiger Nuts) Protect Epithelial Barrier Function in Caco-2 Cells Infected by Salmonella Enteritidis and Promote Lactobacillus plantarum Growth.

Cyperus esculentus L. tubers (tiger nuts) contain different compounds with several intestinal health-promoting properties. Here, we studied the capacity of tiger nuts from Valencia, Spain, to prevent epithelial barrier function disruption induced by Salmonella enteritidis in Caco-2 cell cultures. Paracellular permeability was assessed by transepithelial electrical resistance (TER) and tight junction protein immunolocalization. Moreover, the effect of tiger nuts on S. enteritidis agglutination, oxidative stress, and Lactobacillus plantarum growth was tested. Compared to controls, tiger nuts partially restored TER in S. enteritidis-infected cultures, an effect confirmed by immunolocalization of tight junction proteins ZO-1 and occludin. The results also revealed that this protective effect may be associated with the capacity to agglutinate the pathogen, restore TER in TNFα-stimulated cultures, and reduce reactive oxygen species in H2O2-stimulated cultures. Moreover, they favor L. plantarum growth. In conclusion, this study demonstrates that the tiger nut protects epithelial barrier function by reducing bacterial invasion, along with counteracting TNFα and H2O2 effects, thus giving an additional value to this tuber as a potential functional food.

Mortality and other adverse outcomes in patients with type 2 diabetes mellitus admitted for COVID-19 in association with glucose-lowering drugs: a nationwide cohort study.

BACKGROUND: Limited evidence exists on the role of glucose-lowering drugs in patients with COVID-19. Our main objective was to examine the association between in-hospital death and each routine at-home glucose-lowering drug both individually and in combination with metformin in patients with type 2 diabetes mellitus admitted for COVID-19. We also evaluated their association with the composite outcome of the need for ICU admission, invasive and non-invasive mechanical ventilation, or in-hospital death as well as on the development of in-hospital complications and a long-time hospital stay. METHODS: We selected all patients with type 2 diabetes mellitus in the Spanish Society of Internal Medicine's registry of COVID-19 patients (SEMI-COVID-19 Registry). It is an ongoing, observational, multicenter, nationwide cohort of patients admitted for COVID-19 in Spain from March 1, 2020. Each glucose-lowering drug user was matched with a user of other glucose-lowering drugs in a 1:1 manner by propensity scores. In order to assess the adequacy of propensity score matching, we used the standardized mean difference found in patient characteristics after matching. There was considered to be a significant imbalance in the group if a standardized mean difference > 10% was found. To evaluate the association between treatment and study outcomes, both conditional logit and mixed effect logistic regressions were used when the sample size was ≥ 100. RESULTS: A total of 2666 patients were found in the SEMI-COVID-19 Registry, 1297 on glucose-lowering drugs in monotherapy and 465 in combination with metformin. After propensity matching, 249 patients on metformin, 105 on dipeptidyl peptidase-4 inhibitors, 129 on insulin, 127 on metformin/dipeptidyl peptidase-4 inhibitors, 34 on metformin/sodium-glucose cotransporter 2 inhibitor, and 67 on metformin/insulin were selected. No at-home glucose-lowering drugs showed a significant association with in-hospital death; the composite outcome of the need of intensive care unit admission, mechanical ventilation, or in-hospital death; in-hospital complications; or long-time hospital stays. CONCLUSIONS: In patients with type 2 diabetes mellitus admitted for COVID-19, at-home glucose-lowering drugs showed no significant association with mortality and adverse outcomes. Given the close relationship between diabetes and COVID-19 and the limited evidence on the role of glucose-lowering drugs, prospective studies are needed.

Predicting Clinical Outcome with Phenotypic Clusters in COVID-19 Pneumonia: An Analysis of 12,066 Hospitalized Patients from the Spanish Registry SEMI-COVID-19.

(1) Background: Different clinical presentations in COVID-19 are described to date, from mild to severe cases. This study aims to identify different clinical phenotypes in COVID-19 pneumonia using cluster analysis and to assess the prognostic impact among identified clusters in such patients. (2) Methods: Cluster analysis including 11 phenotypic variables was performed in a large cohort of 12,066 COVID-19 patients, collected and followed-up from 1 March to 31 July 2020, from the nationwide Spanish Society of Internal Medicine (SEMI)-COVID-19 Registry. (3) Results: Of the total of 12,066 patients included in the study, most were males (7052, 58.5%) and Caucasian (10,635, 89.5%), with a mean age at diagnosis of 67 years (standard deviation (SD) 16). The main pre-admission comorbidities were arterial hypertension (6030, 50%), hyperlipidemia (4741, 39.4%) and diabetes mellitus (2309, 19.2%). The average number of days from COVID-19 symptom onset to hospital admission was 6.7 (SD 7). The triad of fever, cough, and dyspnea was present almost uniformly in all 4 clinical phenotypes identified by clustering. Cluster C1 (8737 patients, 72.4%) was the largest, and comprised patients with the triad alone. Cluster C2 (1196 patients, 9.9%) also presented with ageusia and anosmia; cluster C3 (880 patients, 7.3%) also had arthromyalgia, headache, and sore throat; and cluster C4 (1253 patients, 10.4%) also manifested with diarrhea, vomiting, and abdominal pain. Compared to each other, cluster C1 presented the highest in-hospital mortality (24.1% vs. 4.3% vs. 14.7% vs. 18.6%; p < 0.001). The multivariate study identified age, gender (male), body mass index (BMI), arterial hypertension, chronic obstructive pulmonary disease (COPD), ischemic cardiopathy, chronic heart failure, chronic hepatopathy, Charlson's index, heart rate and respiratory rate upon admission >20 bpm, lower PaO2/FiO2 at admission, higher levels of C-reactive protein (CRP) and lactate dehydrogenase (LDH), and the phenotypic cluster as independent factors for in-hospital death. (4) Conclusions: The present study identified 4 phenotypic clusters in patients with COVID-19 pneumonia, which predicted the in-hospital prognosis of clinical outcomes.

Corpora amylacea act as containers that remove waste products from the brain.

Corpora amylacea (CA) in the human brain are granular bodies formed by polyglucosan aggregates that amass waste products of different origins. They are generated by astrocytes, mainly during aging and neurodegenerative conditions, and are located predominantly in periventricular and subpial regions. This study shows that CA are released from these regions to the cerebrospinal fluid and are present in the cervical lymph nodes, into which cerebrospinal fluid drains through the meningeal lymphatic system. We also show that CA can be phagocytosed by macrophages. We conclude that CA can act as containers that remove waste products from the brain and may be involved in a mechanism that cleans the brain. Moreover, we postulate that CA may contribute in some autoimmune brain diseases, exporting brain substances that interact with the immune system, and hypothesize that CA may contain brain markers that may aid in the diagnosis of certain brain diseases.

2-Hydroxy-(4-methylseleno)butanoic Acid Is Used by Intestinal Caco-2 Cells as a Source of Selenium and Protects against Oxidative Stress.

BACKGROUND: Selenium (Se) participates in different functions in humans and other animals through its incorporation into selenoproteins as selenocysteine. Inadequate dietary Se is considered a risk factor for several chronic diseases associated with oxidative stress. OBJECTIVE: The role of 2-hydroxy-(4-methylseleno)butanoic acid (HMSeBA), an organic form of Se used in animal nutrition, in supporting selenoprotein synthesis and protecting against oxidative stress was investigated in an in vitro model of intestinal Caco-2 cells. METHODS: Glutathione peroxidase (GPX) and thioredoxin reductase (TXNRD) activities, selenoprotein P1 protein (SELENOP) and gene (SELENOP) expression, and GPX1 and GPX2 gene expression were studied in Se-deprived (FBS removal) and further HMSeBA-supplemented (0.1-625 µM, 72 h) cultures. The effect of HMSeBA supplementation (12.5 and 625 µM, 24 h) on oxidative stress induced by H2O2 (1 mM) was evaluated by the production of reactive oxygen species (ROS), 4-hydroxy-2-nonenal (4-HNE) adducts, and protein carbonyl residues compared with a sodium selenite control (SS, 5 µM). RESULTS: Se deprivation induced a reduction (P < 0.05) in GPX activity (62%), GPX1 expression, and both SELENOP (33%) and SELENOP expression. In contrast, an increase (P < 0.05) in GPX2 expression and no effect in TXNRD activity (P = 0.09) were observed. HMSeBA supplementation increased (P < 0.05) GPX activity (12.5-625 µM, 1.68-1.82-fold) and SELENOP protein expression (250 and 625 µM, 1.87- and 2.04-fold). Moreover, HMSeBA supplementation increased (P < 0.05) GPX1 (12.5 and 625 µM), GPX2 (625 µM), and SELENOP (12.5 and 625 µM) expression. HMSeBA (625 µM) was capable of decreasing (P < 0.05) ROS (32%), 4-HNE adduct (49%), and protein carbonyl residue (75%) production after H2O2 treatment. CONCLUSION: Caco-2 cells can use HMSeBA as an Se source for selenoprotein synthesis, resulting in protection against oxidative stress.

Volatile and non-volatile/semi-volatile compounds and in vitro bioactive properties of Chilean Ulmo (Eucryphia cordifolia Cav.) honey.

Ulmo honey originating from Eucryphia cordifolia tree, known locally in the Araucania region as the Ulmo tree is a natural product with valuable nutritional and medicinal qualities. It has been used in the Mapuche culture to treat infections. This study aimed to identify the volatile and non-volatile/semi-volatile compounds of Ulmo honey and elucidate its in vitro biological properties by evaluating its antioxidant, antibacterial, antiproliferative and hemolytic properties and cytotoxicity in Caco-2 cells. Headspace volatiles of Ulmo honey were isolated by solid-phase microextraction (SPME); non-volatiles/semi-volatiles were obtained by removing all saccharides with acidified water and the compounds were identified by GC/MS analysis. Ulmo honey volatiles consisted of 50 compounds predominated by 20 flavor components. Two of the volatile compounds, lyrame and anethol have never been reported before as honey compounds. The non-volatile/semi-volatile components of Ulmo honey comprised 27 compounds including 13 benzene derivatives accounting 75% of the total peak area. Ulmo honey exhibited weak antioxidant activity but strong antibacterial activity particularly against gram-negative bacteria and methicillin-resistant Staphylococcus aureus (MRSA), the main strain involved in wounds and skin infections. At concentrations >0.5%, Ulmo honey reduced Caco-2 cell viability, released lactate dehydrogenase (LDH) and increased reactive oxygen species (ROS) production in a dose dependent manner in the presence of foetal bovine serum (FBS). The wide array of volatile and non-volatile/semi-volatile constituents of Ulmo honey rich in benzene derivatives may partly account for its strong antibacterial and antiproliferative properties important for its therapeutic use. Our results indicate that Ulmo honey can potentially inhibit cancer growth at least partly by modulating oxidative stress.

Salmosan, a ß-galactomannan-rich product, in combination with Lactobacillus plantarum contributes to restore intestinal epithelial barrier function by modulation of cytokine production.

Mannan-oligosaccharides (MOSs) are mannose-rich substrates with several intestinal health-promoting properties. The aim of this study was to investigate the potential capacity of Salmosan (S-ßGM), a ß-galactomannan-rich MOS product, to restore epithelial barrier function independently from its capacity to reduce bacterial invasion. In addition, the combination of S-ßGM with the proven probiotic Lactobacillus plantarum (LP) was also tested. Paracellular permeability was assessed by transepithelial electrical resistance (TER) in co-cultures of Caco-2 cells and macrophages (differentiated from THP-1 cells) stimulated with LPS of Salmonella Enteritidis and in Caco-2 cell cultures stimulated with TNF-α in the absence or presence of 500 µg/ml S-ßGM, LP (MOI 10) or a combination of both. In both culture models, TER was significantly reduced up to 25% by LPS or TNF-α stimulation, and the addition of S-ßGM or LP alone did not modify TER, whereas the combination of both restored TER to values of nonstimulated cells. Under LPS stimulation, TNF-α production was significantly increased by 10-fold, whereas IL-10 and IL-6 levels were not modified. The combination of S-ßGM and LP reduced TNF-α production to nonstimulated cell values and significantly increased IL-10 and IL-6 levels (5- and 7.5-fold, respectively). Moreover, S-ßGM has the capacity to induce an increase of fivefold in LP growth. In conclusion, we have demonstrated that S-ßGM in combination with LP protects epithelial barrier function by modulation of cytokine secretion, thus giving an additional value to this MOS as a potential symbiotic.

Salmosan, a ß-Galactomannan-Rich Product, Protects Epithelial Barrier Function in Caco-2 Cells Infected by Salmonella enterica Serovar Enteritidis.

BACKGROUND: One promising strategy for reducing human salmonellosis induced by Salmonella Enteritidis is to supplement animal diets with natural feed additives such as mannan oligosaccharides (MOSs). OBJECTIVE: We sought to investigate the potential role of Salmosan (S-ßGM), an MOS product extremely rich in ß-galactomannan, in preventing epithelial barrier function disruption induced by S. Enteritidis colonization in an in vitro model of intestinal Caco-2 cells in culture. METHODS: Differentiated Caco-2 cells were incubated for 3 h with S. Enteritidis at a multiplicity of infection of 10 in the absence or presence of 500 µg S-ßGM/mL. Paracellular permeability (PP) was assessed by transepithelial electrical resistance (TER), d-mannitol, and fluorescein isothiocyanate-dextran (FD-4) flux. Tight junction proteins and cytoskeletal actin were also localized by confocal microscopy. Reactive oxygen species (ROS) and lipid peroxidation products were evaluated. Scanning and transmission electron microscopy were used to visualize S. Enteritidis adhesion to, and invasion of, the Caco-2 cell cultures. RESULTS: Compared with controls, TER was significantly reduced by 30%, and d-mannitol and FD-4 flux were significantly increased by 374% and 54% in S. Enteritidis-infected cultures, respectively. The presence of S-ßGM in infected cultures induced total recoveries of TER and FD-4 flux to values that did not differ from the control and a partial recovery of d-mannitol flux. These effects were confirmed by immunolocalization of actin, zonula occludens protein 1, and occludin. Similar results were obtained for Salmonella Dublin. The protection of S-ßGM on PP in infected cultures may be associated with a total recovery of ROS production to values that did not differ from the control. Moreover, S-ßGM has the capacity to agglutinate bacteria, leading to a significant reduction of 32% in intracellular S Enteritidis. CONCLUSION: The results demonstrate that S-ßGM contributes to protecting epithelial barrier function in a Caco-2 cell model disrupted by S. Enteritidis.

Monocarboxylate transporter 1 is up-regulated in Caco-2 cells by the methionine precursor DL-2-hydroxy-(4-methylthio)butanoic acid.

The methionine precursor, DL-2-hydroxy-(4-methylthio)butanoic acid (HMTBA), is a synthetic source of dietary methionine, which is widely used as a poultry nutritional supplement. In the intestinal epithelium, HMTBA transport across the apical membrane is mediated by monocarboxylate transporter 1 (MCT1). The first step in biological utilisation of this methionine precursor is the stereospecific conversion of HMTBA to the corresponding keto acid. In the present study, the regulation of trans-epithelial HMTBA transport was investigated in Caco-2 cell monolayers. Differentiated Caco-2 cells were maintained under control conditions (apical compartment: 0.2 mmol/L L-methionine) or in a HMTBA-enriched medium (2 mmol/L HMTBA). The effect of culture on HMTBA transport was evaluated from apical and basolateral kinetic parameters. MCT1 and MCT4 immuno-localisation and gene expression were investigated by confocal microscopy and real-time quantitative RT-PCR, respectively. The results indicated that apical MCT1 was up-regulated by exposure to HMTBA (1.4-fold increase in Vmax without changes in Km). Moreover, total monolayer MCT1 immunoreactivity increased 1.8-fold in HMTBA-supplemented cultures, this effect mainly being localised at the apical membrane. Functional and immuno-localisation data suggest involvement of MCT1 and MCT4 in basolateral HMTBA transport, although, in this case, no effect was observed for HMTBA-enrichment. Molecular analysis confirmed MCT1 mRNA up-regulation (1.8-fold), with no effect on MCT4 mRNA expression. Thus, exposure to HMTBA up-regulates the trans-epithelial transport of this methionine precursor by increasing the expression and the transport capacity of apical MCT1.

The methionine precursor DL-2-hydroxy-(4-methylthio)butanoic acid protects intestinal epithelial barrier function.

DL-2-hydroxy-(4-methylthio)butanoic acid (HMTBA) is a source of dietary methionine (Met) that is widely used in poultry nutrition. We have previously shown that HMTBA is preferentially diverted to the transsulfuration pathway, which gives antioxidant metabolites such as taurine and glutathione. Therefore, here we hypothesize that this Met source can protect epithelial barrier function in an in vitro model of intestinal inflammation of Caco-2 cells. The results show that HMTBA prevents the increase in paracellular permeability induced by H2O2 or tumour necrosis factor-α. This effect can be attributed to the increased production of taurine and reduced glutathione. Similar results were obtained for DL-Met, although the protective role of the amino acid was less pronounced than that of the hydroxy analogue. In conclusion, the diversion to the transsulfuration pathway means that this Met precursor is of greater value than previously thought, due to its capacity to improve intestinal homeostasis and the quality of poultry products destined for human consumption.

In vitro study of the cytotoxicity and antiproliferative effects of surfactants produced by Sphingobacterium detergens.

The application of biosurfactants in the biomedical field is growing due to their antimicrobial activity, low cytotoxicity and ability to induce apoptosis in cancer cells. In the light of this therapeutic potential, as well as possible applications in cosmetics or as drug vehicles in pharmaceutical products, a new biosurfactant produced by Sphingobacterium detergens was investigated for its haemolytic activity and cytotoxic and antiproliferative effects in different cell lines. Fraction A showed 100% haemolysis in rabbit erythrocytes, but in Fraction B the rate was only 83%. When comparing cytotoxicity values (IC50) of the two fractions in model fibroblast and keratinocyte cell cultures, Fraction B was less cytotoxic, showing lower values than the reference compound SDS, indicating low skin irritability. Finally, in non-differentiated intestinal Caco-2 cultures, Fractions A and B reduced cell proliferation and induced apoptosis by 44% and 75%, respectively. According to these results, biosurfactants produced by S. detergens have potential application in cosmetic and pharmaceutical formulations.

Effect of eicosapentaenoic acid-derived prostaglandin E3 on intestinal epithelial barrier function.

Prostaglandins (PG) are inflammatory mediators derived from arachidonic or eicosapentaenoic acid giving rise to the 2-series or the 3-series prostanoids, respectively. Previously, we have observed that PGE2 disrupts epithelial barrier function. Considering the beneficial effect of fish oil consumption in intestinal inflammatory processes, the aim of this study was to assess the role of PGE3 on epithelial barrier function assessed from transepithelial electrical resistance and dextran fluxes in Caco-2 cells. The results indicate that PGE3 increased paracellular permeability (PP) to the same extent as PGE2, through the interaction with EP1 and EP4 receptors and with intracellular Ca(2+) and cAMP as the downstream targets. Moreover, we observed a redistribution of tight junction proteins, occludin and claudin-4. In conclusion, PGE3 is able to increase PP thus leading to reconsider the role of PGE2/PGE3 ratio in the beneficial effects of dietary fish oil supplementation in the disruption of barrier function.

ß-Galactomannan and Saccharomyces cerevisiae var. boulardii modulate the immune response against Salmonella enterica serovar Typhimurium in porcine intestinal epithelial and dendritic cells.

Salmonella enterica serovar Typhimurium is a facultative intracellular pathogen that causes inflammation, necrosis, and diarrhea in pigs, as well as being an important source of food-borne diseases in humans. Probiotics and prebiotics are promising alternatives to antibiotics to control and prevent intestinal infections. The present work investigated a recently developed ß-galactomannan (ßGM) prebiotic compared to the proven probiotic Saccharomyces cerevisiae var. boulardii on porcine ileum intestinal epithelial cells (IECs) of the IPI-2I line and monocyte-derived dendritic cells (DCs) cocultured in vitro with Salmonella. We observed that both S. cerevisiae var. boulardii and ßGM inhibited the association of Salmonella with IECs in vitro. Our data indicated that ßGM has a higher ability than S. cerevisiae var. boulardii to inhibit Salmonella-induced proinflammatory mRNA (cytokines tumor necrosis factor alpha [TNF-α], interleukin-1α [IL-1α], IL-6, and granulocyte-macrophage colony-stimulating factor [GM-CSF] and chemokines CCL2, CCL20, and CXCL8) and at protein levels (IL-6 and CXCL8). Additionally, ßGM and S. cerevisiae var. boulardii induced some effects on DCs that were not observed on IECs: ßGM and S. cerevisiae var. boulardii showed slight upregulation of mRNA for TNF-α, GM-CSF, and CCR7 receptor on porcine monocyte-derived dendritic cells (DCs). Indeed, the addition of ßGM or S. cerevisiae var. boulardii on DCs cocultured with Salmonella showed higher gene expression (mRNA) for TNF-α, GM-CSF, and CXCL8 compared to that of the control with Salmonella. In conclusion, the addition of ßGM inhibits Salmonella-induced proinflammatory profiles in IECs but may promote DC activation, although associated molecular mechanisms remain to be elucidated.

Intestinal cell conversion of DL-2-hydroxy-(4-methylthio)butanoic acid in vitro: dietary up-regulation by this methionine precursor.

DL-2-Hydroxy-(4-methylthio)butanoic acid (HMTBA) is a synthetic source of dietary methionine (Met) widely used in poultry nutrition. HMTBA is transported in the intestinal epithelium by the monocarboxylate transporter 1, after which its biological utilisation relies on its conversion to L-Met. This process involves stereospecific HMTBA oxidation to 2-keto-(4-methylthio)butanoic acid (KMB) and transamination to L-Met. In the present study, we examined HMTBA conversion to L-Met, further incorporation into cellular proteins and the regulation of both processes by HMTBA supplementation in differentiated intestinal Caco-2 cells. The results showed D- and L-HMTBA oxidation in the enterocytes, this process being up-regulated by HMTBA. The data also revealed that KMB transamination is not linked to a specific amino group donor. However, the branched-chain amino acid L-leucine is the preferred amino group donor. Furthermore, transamination was not affected by HMTBA availability. The incorporation of radioactivity from HMTBA into cellular proteins was not significantly different from that of L-Met and was not affected by HMTBA supplementation. In conclusion, the results reveal the capacity of Caco-2 cells to convert HMTBA to L-Met and the up-regulation of conversion by nutritional HMTBA supplementation, thus highlighting the contribution of the intestinal epithelium in the utilisation of HMTBA as a dietary source of Met.

Intracellular mechanisms involved in docosahexaenoic acid-induced increases in tight junction permeability in Caco-2 cell monolayers.

We recently showed that enrichment of Caco-2 cells with docosahexaenoic acid (DHA) increases lipid peroxidation and the formation of hydrogen peroxide and peroxynitrite, which disrupt the epithelial barrier function. Studies were designed to test whether the participation of phospholipase C (PLC)/Ca(2+)/protein kinase C (PKC), cyclooxygenase (COX), and 5-lipooxygenase pathways are involved in mediating the effects of DHA. Paracellular permeability was assessed from D-mannitol flux and transepithelial electrical resistance (TER) in differentiated Caco-2 cell monolayers incubated in control or DHA-enriched conditions (100 micromol/L). The effect of DHA was prevented by U73122 (PLC inhibitor), chelerytrine (PKC inhibitor), and 1-[5-iodonaphtalene-1-sulfonyl]-1H-hexahydro-1,4-diazepine hydrochloride (myosin light chain kinase inhibitor). In contrast, the effect of DHA was enhanced by A23187 (Ca(2+) ionophore) and BAPTA-AM (Ca(2+) chelator). Indomethacin (COX inhibitor) and AA961 (5-lipooxygenase inhibitor) also prevented the changes in D-mannitol flux induced by DHA, but no effect was detected for TER. Moreover, occludin and ZO-1 immunogold staining microscopy showed that the increase in paracellular permeability was accompanied by the redistribution of both tight junction proteins. We conclude that the disruption of epithelial barrier function by DHA is partly mediated by the PLC/Ca(2+)/PKC pathway and by the formation of eicosanoids.

PGE2 promotes Ca2+-mediated epithelial barrier disruption through EP1 and EP4 receptors in Caco-2 cell monolayers.

We recently demonstrated that PGE(2) induces the disruption of the intestinal epithelial barrier function. In the present study, our objectives were to study the role of PGE(2) receptors (EP(1)-EP(4)) and the signaling pathways involved in this event. Paracellular permeability (PP) was assessed in differentiated Caco-2 cell cultures from d-mannitol fluxes and transepithelial electrical resistance (TER) in the presence of different PGE(2) receptor agonists (carbacyclin, sulprostone, butaprost, ONO-AE1-259, ONO-AE-248, GR63799, and ONO-AE1-329) and antagonists (ONO-8711, SC-19220, AH-6809, ONO-AE3-240, ONO-AE3-208, and AH-23848). The results indicate that EP(1) and EP(4) but not EP(2) and EP(3) might be involved in PP regulation. These effects were mediated through PLC-inositol trisphosphate (IP(3))-Ca(2+) and cAMP-PKA signaling pathways, respectively. We also observed an increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) strengthened by cAMP formation indicating a cross talk interaction of these two pathways. Moreover, the participation of a conventional PKC isoform was shown. The results also indicate that the increase in PP may be correlated with the redistribution of occludin, zona occludens 1 (ZO-1), and the perijunctional actin ring together with an increase in myosin light chain kinase activity. Although the disruption of epithelial barrier function observed in inflammatory bowel disease (IBD) patients has been traditionally attributed to cytokines, the present study focused on the role of PGE(2) in PP regulation, as mucosal levels of this eicosanoid are also increased in these inflammatory processes.