Surfactant-like particles mediate tissue-specific functions in epithelial cells

Effects of a Sudden Drop in Salinity on Scapharca subcrenata Antioxidant Defenses and Metabolism Determined Using LC-MS Non-targeted Metabolomics

In this experiment, the effects of a sudden drop in salinity on the antioxidant defense system and related gene expression of the ark shell Scapharca subcrenata were examined. The sudden drop in seawater salinity after a rainstorm was simulated, and subsequently differentially expressed metabolic markers were identified by LC-MS non-targeted metabolomics. When the salinity dropped to 14‰ (S14), the total anti-oxidant content, activity of Na⁺/K⁺-ATPase, superoxide dismutase (SOD), and catalase (CAT), content of malondialdehyde, and expression levels of Mn-SOD, CAT, and C-type lectin of S. subcrenata were significantly higher than in groups with salinity of 22‰ (S22) or 30‰ (S30) (P < 0.05). The activity of glutathione peroxidase (GPx), the content of reduced glutathione, and the expression levels of GP_x were not significantly different between S14 and S22, but the values in each group were significantly higher than those in S30 (P < 0.05). Using the metabolomics technique, 361, 271, and 264 metabolites with significant differences were identified from S22 vs. S14, S30 vs. S14, and S30 vs. S22, respectively. The drop in salinity was accompanied by up-regulation of phosphatidylcholine (PC) (20:4 (5Z, 8Z, 11Z, 14Z)/P-18: 1 (11Z)), PC (16:0/22: 6 (4Z, 7Z, 10Z, 13Z, 16Z, 19Z)), phosphatidylethanolamine (PE) (18:4 (6Z, 9Z, 12Z, 15Z)/24:1 (15Z)), phosphatidylinositol (PI) (20:1 (11Z)/0:0), phalluside-1, C16 sphinganine, and LacCer (d18:0/14:0) and by significant down-regulation of PI-Cer (d18:1/14:0) and PE (14:0/16:1(9Z). The results of this study illustrate how these nine metabolites can be used as metabolic markers for the response of S. subcrenata to a sudden drop in salinity. They also provide the theoretical groundwork for selection of bottom areas with salinity that is optimal for release and proliferation of S. subcrenata, which is needed to restore the declining populations of this species.

Glutathione as an antioxidant marker: determination of glutathione concentration in the breast muscles and liver of broilers supplemented with different selenium sources

The aim of the study was to determine the influence of different selenium sources on antioxidant properties. The glutathione (GSH) concentration and glutathione peroxidase (GPx) activity were measured in the breast muscles and liver of 60 one-day-old broiler chickens. Another goal was to compare these indices with the weights of individual tissues and the live weight of broilers. The broilers were divided into 4 groups according to the selenium source: group 1 (control), group 2 (selenized yeast), group 3 (selenomethionine), group 4 (sodium selenite). Treatment groups were supplemented with 0.2 mg of additional selenium/kg. No significant changes in the hepatic GSH concentrations (P> 0.05) were found in the experimental groups compared to control. Significantly higher GSH concentration (P< 0.05) was found in breast muscles of broilers in group 4 (sodium selenite) compared to control. However, no positive effect of selenium supplementation in the form of sodium selenite was observed. The differences in the GPx activity in breast muscles and liver between the experimental groups and the control group were not significant (P> 0.05). No significant differences were recorded in the experimental groups compared to control in relation to the GSH concentration and GPx activity measured in the tissues. A significantly positive correlation was noted between mean GPx activity in breast muscle and breast muscle weight (P< 0.01; r = 0.3790) and live weight (P< 0.05; r = 0.2690). Although changes in the GSH concentration and GPx activity were recorded in some experimental groups, the selected dose of additional selenium appeared to be too low to affect these concentrations and the antioxidant defence system.

Probiotics isolated from yaks improves the growth performance, antioxidant activity, and cytokines related to immunity and inflammation in mice

BACKGROUND

Yaks living in the high-altitude hypoxic environment of Tibetan plateau (3600 m) have special gut microbes. However, it is still little research on yak probiotics until now. Therefore, the purpose of our study was to evaluate the growth promoting effect, antioxidant capability, immune effect, and anti-inflammatory ability of Bacillus subtilis and Bacillus velezensis isolated from Tibetan yaks in mice model.

RESULTS

The results showed that the isolated strains supplementation not only improve the growth performance but also increased the length of villus in the small intestine and intestinal digestive enzyme activity. Importantly, we observed that the T-AOC, SOD, and GSH-PX levels were increased and the MDA content was reduced in probiotic-treated mice, which implied that probiotics supplementation can ameliorate the antioxidative activity of mice. The levels of AST and ALT correlated with the hepatic injury were reduced and the levels of AKP, TP, GLB, ALB, Ca, and P were markedly higher than those in the control group. Additionally, mice treated with probiotics exhibited higher serum IgG, IgM and IgA, which can reflect the immune status to some extent. At the same time, the major pro-inflammatory factor TNF-α, IL-6, and IL-8 were down-regulated and the anti-inflammatory factor IL-10 was up-regulated compared with the control groups.

CONCLUSIONS

In conclusion, these results demonstrated that Bacillus subtilis and Bacillus velezensis supplementation can increase overall growth performance and ameliorate the blood parameters related to inflammation and immunity of mice.

Evolution, Development, and Function of the Pulmonary Surfactant System in Normal and Perturbed Environments

Surfactant lipids and proteins form a surface active film at the air-liquid interface of internal gas exchange organs, including swim bladders and lungs. The system is uniquely positioned to meet both the physical challenges associated with a dynamically changing internal air-liquid interface, and the environmental challenges associated with the foreign pathogens and particles to which the internal surface is exposed. Lungs range from simple, transparent, bag-like units to complex, multilobed, compartmentalized structures. Despite this anatomical variability, the surfactant system is remarkably conserved. Here, we discuss the evolutionary origin of the surfactant system, which likely predates lungs. We describe the evolution of surfactant structure and function in invertebrates and vertebrates. We focus on changes in lipid and protein composition and surfactant function from its antiadhesive and innate immune to its alveolar stability and structural integrity functions. We discuss the biochemical, hormonal, autonomic, and mechanical factors that regulate normal surfactant secretion in mature animals. We present an analysis of the ontogeny of surfactant development among the vertebrates and the contribution of different regulatory mechanisms that control this development. We also discuss environmental (oxygen), hormonal and biochemical (glucocorticoids and glucose) and pollutant (maternal smoking, alcohol, and common "recreational" drugs) effects that impact surfactant development. On the adult surfactant system, we focus on environmental variables including temperature, pressure, and hypoxia that have shaped its evolution and we discuss the resultant biochemical, biophysical, and cellular adaptations. Finally, we discuss the effect of major modern gaseous and particulate pollutants on the lung and surfactant system.

Effects of dietary concentrations of methionine on growth performance and oxidative status of broiler chickens with different hatching weight

1. A study was conducted to evaluate the effects of two hatching weight (HW) levels and two dietary concentrations of methionine on the growth performance and oxidative status of broilers. Male Arbor Acres chickens were divided into two groups on their HW (low and high HW, H and L). Each HW group was then distributed into two subgroups, of similar HW, receiving either low or high dietary concentrations of methionine (4.9 g methionine/kg, LM; 5.9 g methionine/kg, HM). Thus, all day-old birds were distributed into 4 treatments (H-LM, H-HM, L-LM, L-HM) × 6 replicates × 10 birds for 21 d. 2. Broilers with high HW were heavier than those with low HW during the 21 d assay, which appeared to result from increased body weight gain rather than improved feed conversion efficiency. A higher dietary concentration of methionine (5.9 g/kg) improved growth performance of broilers with low HW in terms of body weight gain and feed conversion ratio. 3. Broilers with different HW had similar antioxidant status both in serum and liver. 4. Broilers given a diet containing 5.9 g/kg methionine had enhanced serum superoxide dismutase (SOD) activity and decreased hepatic malondialdehyde (MDA) content at day 7. 5. Broilers given a diet containing 5.9 g/kg methionine had a higher hepatic reduced glutathione (GSH):glutathione disulphide (GSSG) ratio than those given a diet containing 4.9 g/kg methionine at day 21. High dietary methionine concentration reduced hepatic GSH content and glutathione peroxidase (GPX) activity of broilers with high HW at day 7 and at day 21, respectively, but increased hepatic GSH content of broilers with low HW at day 7. 6. Although broilers with different HW had similar oxidative status as indicated by several parameters in blood and liver, HW can have positive effects on the subsequent growth performance of broilers, and a higher dietary methionine concentration (5.9 g/kg) can improve growth performance and antioxidant status in broilers exhibiting low HW.

Influence of different histidine sources and zinc supplementation of broiler diets on dipeptide content and antioxidant status of blood and meat

1. The objective of this study was to investigate how a diet containing spray-dried blood cells (SDBC) (4%) with or without zinc (Zn) would affect the concentration of two histidine heterodipeptides and the antioxidant status of broiler blood and breast muscles. 2. The study was carried out on 920 male Flex chickens randomly assigned to 4 dietary treatments: I - control, II - diet I with SDBC, III - diet I with SDBC and supplemented with Zn and IV - diet I supplemented with L-histidine. Birds were raised on floor littered with wood shavings, given free access to water and fed ad libitum. Performance indices were measured on d 1, 21 and 42. 3. The activity of antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase was analysed in plasma, erythrocytes and muscle tissue. The total antioxidant capacity of plasma and breast muscles was measured by 2,2-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, as well as by ferric reducing antioxidant power (FRAP). Carnosine/anserine content of meat and plasma were determined using HPLC. Diets and breast muscles were analysed for amino acid profile and selected microelement content. 4. Histidine supplementation of the diet increased glutathione peroxidase activity in plasma and superoxide dismutase activity in erythrocytes. Moreover, the addition of SDBC or pure histidine in the diet increased histidine dipeptide content and activated enzymatic and non-enzymatic antioxidant systems in chicken blood and muscles. However, it led to lower growth performance indices. 5. The enrichment of broiler diets with Zn increased the antioxidant potential and the activity of superoxide dismutase in plasma, which was independent of the histidine dipeptide concentration. Zn supplementation combined with SDBC in a broiler diet led to the increase of superoxide dismutase and glutathione peroxidase activity, but it did not affect the radical-scavenging or ferric iron reduction abilities of muscles.

Phosphatidylcholine as a constituent in the colonic mucosal barrier--physiological and clinical relevance

Phosphatidylcholine (PC) is an important constituent of the gastrointestinal tract. PC molecules are not only important in intestinal cell membranes but also receiving increasing attention as protective agents in the gastrointestinal barrier. They are largely responsible for establishing the hydrophobic surface of the colon. Decreased phospholipids in colonic mucus could be linked to the pathogenesis of ulcerative colitis, a chronic inflammatory bowel disease. Clinical studies revealed that therapeutic addition of PC to the colonic mucus of these patients alleviated the inflammatory activity. This positive role is still elusive, however, we hypothesized that luminal PC has two possible functions: first, it is essential for surface hydrophobicity, and second, it is integrated into the plasma membrane of enterocytes and it modulates the signaling state of the mucosa. The membrane structure and lipid composition of cells is a regulatory component of the inflammatory signaling pathways. In this perspective, we will shortly summarize what is known about the localization and protective properties of PC in the colonic mucosa before turning to its evident medical importance. We will discuss how PC contributes to our understanding of the pathogenesis of ulcerative colitis and how reinforcing the luminal phospholipid monolayer can be used as a therapeutic concept in humans.

Use of Silybum marianum fruit extract in broiler chicken nutrition: influence on performance and meat quality

The present study aimed at evaluating the effects of different doses of silymarin in diet on broiler performances and meat quality. For the trial, 180 male chicks (ROSS 508), were allocated in to three groups (S0, S40 and S80) of 60 animals each receiving a basal diet supplemented with 0 ppm, 40 ppm and 80 ppm of a sylimarin (provided by a dry extract of Silybum marianum fruits) respectively. During the trial feed consumption and live body weight were taken every 20 days. At the age of 40 and 60 days blood samples were taken in order to evaluate protein, aspartate aminotransferase, cholesterol, tryglicerides and uric acid. At the age of 60 days animals were slaughtered, dressing percentages were evaluated and samples of breast and meat were taken to evaluate chemical composition and susceptibility of lipid peroxidation by means of thiobarbituric acid reactive substances. Silymarin at the tested doses did not affect growth performances but slightly affected slaughtering yields negatively, no specific hepatoprotective effect was found. Treatments reduced lipid content of both breast and thigh and increased muscles resistance to oxidative stress.

High-fat enteral nutrition reduces endotoxin, tumor necrosis factor-alpha and gut permeability in bile duct-ligated rats subjected to hemorrhagic shock

BACKGROUND/AIMS

Cholestatic patients are prone to septic complications after major surgery due to an increased susceptibility to endotoxin and hypotension. High-fat enteral nutrition reduces endotoxin after hemorrhagic shock. However, it is unknown whether this nutritional intervention is protective in biliary obstruction. We investigated the effect of high-fat enteral nutrition on endotoxin, tumor necrosis factor-alpha (TNF-alpha) and intestinal permeability in cholestatic rats subjected to hemorrhagic shock.

METHODS

Bile duct-ligated (BDL) rats were fasted or fed with low-fat or high-fat enteral nutrition before hemorrhagic shock. Blood and tissue samples were taken after 90 min.

RESULTS

Plasma endotoxin decreased after hemorrhagic shock in BDL-rats fed with high-fat nutrition compared to fasted (P<0.01) and low-fat treated rats (P<0.05). Additionally, circulating TNF-alpha was reduced in BDL-rats pretreated with high-fat nutrition compared to fasted rats (P<0.01). The increased intestinal permeability to macromolecules was reduced by high-fat enteral nutrition, whereas bacterial translocation did not significantly change. Simultaneously, tight junction distribution in ileum and colon was disrupted in non-treated BDL-rats but remained unchanged in high-fat pretreated BDL-rats.

CONCLUSIONS

High-fat enteral nutrition protects against endotoxin-mediated complications independently of intraluminal bile. These results provide a potential new strategy to prevent endotoxin-mediated complications in cholestatic patients undergoing major surgery.

The Origin and Evolution of the Surfactant System in Fish: Insights into the Evolution of Lungs and Swim Bladders

Several times throughout their radiation fish have evolved either lungs or swim bladders as gas-holding structures. Lungs and swim bladders have different ontogenetic origins and can be used either for buoyancy or as an accessory respiratory organ. Therefore, the presence of air-filled bladders or lungs in different groups of fishes is an example of convergent evolution. We propose that air breathing could not occur without the presence of a surfactant system and suggest that this system may have originated in epithelial cells lining the pharynx. Here we present new data on the surfactant system in swim bladders of three teleost fish (the air-breathing pirarucu Arapaima gigas and tarpon Megalops cyprinoides and the non-air-breathing New Zealand snapper Pagrus auratus). We determined the presence of surfactant using biochemical, biophysical, and morphological analyses and determined homology using immunohistochemical analysis of the surfactant proteins (SPs). We relate the presence and structure of the surfactant system to those previously described in the swim bladders of another teleost, the goldfish, and those of the air-breathing organs of the other members of the Osteichthyes, the more primitive air-breathing Actinopterygii and the Sarcopterygii. Snapper and tarpon swim bladders are lined with squamous and cuboidal epithelial cells, respectively, containing membrane-bound lamellar bodies. Phosphatidylcholine dominates the phospholipid (PL) profile of lavage material from all fish analyzed to date. The presence of the characteristic surfactant lipids in pirarucu and tarpon, lamellar bodies in tarpon and snapper, SP-B in tarpon and pirarucu lavage, and SPs (A, B, and D) in swim bladder tissue of the tarpon provide strong evidence that the surfactant system of teleosts is homologous with that of other fish and of tetrapods. This study is the first demonstration of the presence of SP-D in the air-breathing organs of nonmammalian species and SP-B in actinopterygian fishes. The extremely high cholesterol/disaturated PL and cholesterol/PL ratios of surfactant extracted from tarpon and pirarucu bladders and the poor surface activity of tarpon surfactant are characteristics of the surfactant system in other fishes. Despite the paraphyletic phylogeny of the Osteichthyes, their surfactant is uniform in composition and may represent the vertebrate protosurfactant.

Evidence of luminal phosphatidylcholine secretion in rat ileum

BACKGROUND

Intestinal mucus not only facilitates substrate absorption, but also forms a hydrophobic, phosphatidylcholine (PC) enriched, barrier against luminal gut contents.

METHODS

For evaluation of the origin of PC in intestinal mucus, we first analyzed the mucus PC in mice with absent biliary phospholipid secretion (mdr2 (-/-) mice) using electrospray ionization (ESI) tandem mass spectroscopy (MS/MS). Second, in situ perfused rat jejunum, ileum and colon were analyzed after i.v. bolus injections of 155 pmol [(3)H]-PC. Additional in vitro experiments were performed with isolated mucosal cells after incubation with the PC precursor [(3)H]-choline.

RESULTS

In mdr2 (-/-) mice and control animals no significant quantitative difference in mucus PC was found, indicating that mucus PC is of intestinal and not biliary origin. In situ perfusion studies detected intestinal secretion of [(3)H]-PC, which was stimulated in presence of 2 mM taurocholate (TC). Secretion rates of [(3)H]-PC were highest in ileum (9.0+/-0.8 fmol h(-1)xcm(-1)), lower in jejunum (4.3+/-0.5) and minimal in colon (0.8+/-0.2). It compares to an intestinal secretion of native PC originating to 64% from bile, 9% from jejunum, 28% from ileum, and 1% from colon. Complementary in vitro studies showed 30-min secretion rates for [(3)H]-PC to be highest in enterocytes from ileum (26.5+/-5.3% of intracellular [(3)H]-PC) and jejunum (19.8+/-2.9%), and significantly lower in colonocytes (8.4+/-1.3%).

CONCLUSION

PC in the intestinal mucus originates from secretion by ileal and jejunal enterocytes.

Altered glycosylation of surfactant and brush border membrane of the small intestine in response to surgical manipulation

BACKGROUND

Surgical stress can lead to bacterial translocation from the intestine into systemic circulation. Adherence of bacteria onto the glycoconjugates of the brush border membrane (BBM) and surfactant coat (SLP) of the mucosal cells is the first step in the translocation of luminal bacteria. Our earlier study showed that surgical manipulation of the intestine results in oxidative stress leading to structural and functional alterations in the mucosa. This study looks at the effect of surgical manipulation on the glycoconjugate alterations of SLP and BBM.

MATERIALS AND METHODS

SLP and BBM were isolated from control and after surgical manipulation and the sugar composition was analyzed. Bacterial adherence using E. coli isolated from cecum was compared after coating microtiter plates with SLP or BBM isolated from control and after surgical manipulation.

RESULTS

An increase in various sugars was seen after surgical manipulation both in SLP and BBM and this increase was maximum at 12 h after surgery. These alterations increased bacterial adherence onto SLP and BBM. Inhibiting superoxide generation by allopurinol treatment prior to surgical manipulation prevented glycosylation alteration and bacterial adherence.

CONCLUSION

Surgical manipulation results in altered glycoconjugates of SLP and BBM which leads to increased bacterial adherence. These alterations are probably brought about by oxygen-free radicals. This is clinically significant because postsurgical complications such as sepsis may be brought about by altered glycosylation.

Pulmonary surfactant: the key to the evolution of air breathing

Pulmonary surfactant controls the surface tension at the air-liquid interface within the lung. This system had a single evolutionary origin that predates the evolution of the vertebrates and lungs. The lipid composition of surfactant has been subjected to evolutionary selection pressures, particularly temperature, throughout the evolution of the vertebrates.