Understanding intestinal lipopolysaccharide permeability and associated inflammation

Lipopolysaccharide (LPS) and the inflammation associated with its stimulation of the innate immune responses can have major implications for human and animal health and production. This dissertation research goal was to further understand dietary modulation of intestinal LPS permeability and LPS associated inflammation. Additionally, we sort to examine LPS detoxification and the relationship LPS has with swine health and feed efficiency. High caloric and high dietary fat increases the risk of endotoxemia which can result in a low grade inflammation, a predisposing factor for common metabolic diseases such as Type II diabetes and atherosclerosis. However, little is known about the effect of dietary oil fatty acid composition on intestinal LPS permeability and postprandial endotoxemia. Therefore, we examined whether dietary oil composition differentially modulated intestinal LPS permeability and postprandial endotoxemia. Our in vivo and ex vivo research using pigs and isolated pig intestinal tissues indicated that a single administration of oils rich in long chain n-3 polyunsaturated fatty acids (PUFA), such as fish oil and cod liver oil, decreases LPS permeability and postprandial circulating LPS levels (P\u3c0.05). Furthermore, oils rich in saturated fatty acids, such as coconut oil, augmented LPS permeability and postprandial endotoxemia (P\u3c0.05). Mechanistically, this may be associated with the structure and function of cell membrane lipid raft microdomain structures. Dietary long chain n-3 PUFA such as eicosapentaenoic acid (EPA) and docoasahexaenoic acid (DHA) have been shown to antagonize LPS signaling. Therefore, we examined the ability of dietary EPA and DHA to attenuate intestinal LPS permeability and lipid raft localization of key LPS signaling proteins. Long term dietary EPA and DHA supplementation to pigs enriched intestinal epithelial membrane with EPA and DHA (P\u3c0.05). Phospholipid fatty acid composition of the lipid raft fractions also revealed enrichment of phosphatidyl ethanolamine and phosphatidyl serine with EPA and DHA. Mechanistically, membrane EPA and DHA enrichment decreased localization of LPS signaling proteins, TLR4 and CD14, into ileum and colon lipid raft microdomains. Collectively, this decreased ex vivo LPS permeability and circulating LPS concentrations (P\u3c0.05). Interestingly, an acute systemic inflammatory challenge resulted in a decreased localization of TLR4 and CD14 into lipid rafts, which has the potential to desensitize the pigs to a subsequent immune challenge otherwise known as LPS tolerance. The ability of the maternal diet and prenatal nutrition to impact postnatal growth, development and health has received much attention in recent years. Knowing that DHA and EPA can regulate the innate immune response to an LPS challenge, we wanted to study if maternal n-3 PUFA supplementation of n-3 PUFA could modulate an acute inflammatory challenge in the offspring later in life. Sows and piglets received nutrition devoid or enriched with EPA and DHA during gestation and lactation or throughout life from gestation to ten weeks of age. The offspring was then challenged with LPS or saline to initiate an inflammatory response and buffy coats isolated 4 h post challenge. Interestingly, maternal n-3 PUFA supplementation attenuated the LPS induced inflammatory response in the offspring late in the nursery phase of growth (P\u3c0.05). This was comparable to that of continuous n-3 PUFA supplementation. Both treatment groups exposed to DHA and EPA had a decreased febrile and serum TNF-alpha; cytokine response to LPS, buffy coat mRNA abundance of TNF-alpha;, IL-1beta; and IL-10 and the mRNA abundance of the LPS signaling proteins, TLR4, CD14 and Myd88, compared to control group (P\u3c0.05). Lastly, we used pig lines divergently selected for residual feed intake (RFI, with low RFI being more efficient compared to high RFI) to understand the relationship between intestinal barrier integrity, LPS and associated inflammation with pig feed efficiency. Our research indicates that HRFI pigs seem to be undergoing a greater level of basal inflammation contrary to pigs selected for LRFI. The LRFI pigs had a lower circulating endotoxin concentration, more robust intestinal and liver LPS detoxification and higher active anti-microbial enzymes including alkaline phosphatase and lysozyme (P\u3c0.05). Furthermore, LRFI pigs had a reduced activity of the inflammatory biomarker enzyme myeloperoxidase (P\u3c0.05). Altogether, LPS and low grade inflammation may partially explain the divergence in feed efficiency and RFI in grow-finisher pigs

Drivers of sub-supplier social sustainability compliance: An emerging economy perspective

Purpose: Tragic incidents like the Rana Plaza building collapse call into question the value and effectiveness of supplier codes of conduct (SCC) used in multi-tier supply chains. This paper investigates the drivers of sub-supplier social sustainability compliance from the perspective of suppliers that adopt a double agency role by complying with buyer-imposed SCC while managing sub-supplier compliance on behalf of the buyer. Design/Methodology: This research adopts a sequential, mixed-methods approach. The qualitative phase develops a conceptual model with the aid of the extant literature and semi-structured interviews with 24 senior manufacturing professionals. The quantitative phase uses hierarchical regression analysis to test the conceptual model using survey data from 159 apparel suppliers based in India. Findings: The findings reveal that sub-supplier compliance is positively impacted by effective buyer-supplier governance and by the focal supplier having a strategic partnership with the sub-supplier. Conversely, price pressure on sub-suppliers adversely impacts their compliance, while the institutional pressure on them to comply is generally ineffective. Research Limitations: The context of the study is limited to the apparel manufacturing industry in India. Practical implications: To improve SCC compliance rates, buyers and focal suppliers should actively develop strategic partnerships with selected upstream supply chain actors; should set a reasonable price across the supply chain; and, should include specific sub-supplier compliance requirements in the supply contract. The findings also suggest the need to develop social sustainability protocols that are cognisant of regional contexts. Originality/Value: Given the absence of prior research on SCC implementation by sub-suppliers, this study represents a pioneering empirical study into such multi-tier sourcing arrangements. It provides strong support that sub-supplier governance arrangements differ from those typically found in the focal supplier layer. It also provides empirical evidence of the critical factors that encourage sub-supplier compliance within the apparel industry of an emerging economy

Supply Chain Integration Barriers to Port-Centric Logistics—An Emerging Economy Perspective

Despite the growing interest in supply chain integration and port performance in the maritime literature, there is a lack of detailed studies into the barriers to integration in port-centric logistics. This study explores the barriers to port-centric supply chain integration from an emerging economy and multistakeholder perspective by using the DEMATEL (Decision Making-Trial and Evaluation Laboratory) analysis technique. The findings indicate that institutional requirements, lack of awareness by stakeholders, and port-centric supply chain integration all significantly impact supply chain projects that have been designed to offer maximum value to customers at a low cost. Other crucial barriers include the absence of benchmarking standards and lack of an innovation culture. The policy and managerial implications are explained

Bitter Compounds Decrease Gastric Emptying and Influence Intestinal Nutrient Transport

The effect of bitter tasting compounds on gastric emptying and nutrient transport from the intestine was studied using in vivo and ex vivo models. Sixteen pigs were fed a diet containing the bitter compound phenylthiocarbamide (PTC). The animals were euthanized 45 minutes postprandially and gastric contents were measured to quantify the gastric retention. Additionally, freshly isolated small intestines were mounted into modified Ussing chambers to study the effects of PTC on ex vivo nutrient transport. In summary, bitter compounds decreased the gastric emptying in vivo and increased the nutrient transport ex vivo. Further, cell culture studies identified that bitter compounds might exert their action through stimulating the secretion of the intestinal hormone cholecystokinin (CCK) from the enteroendocrine cells by increasing the intracellular calcium concentrations. Altogether, these data suggest that bitter compounds regulate feed intake and nutrient transport

Dietary oil composition differentially modulates intestinal endotoxin transport and postprandial endotoxemia

Background: Intestinal derived endotoxin and the subsequent endotoxemia can be considered major predisposing factors for diseases such as atherosclerosis, sepsis, obesity and diabetes. Dietary fat has been shown to increase postprandial endotoxemia. Therefore, the aim of this study was to assess the effects of different dietary oils on intestinal endotoxin transport and postprandial endotoxemia using swine as a model. We hypothesized that oils rich in saturated fatty acids (SFA) would augment, while oils rich in n-3 polyunsaturated fatty acids (PUFA) would attenuate intestinal endotoxin transport and circulating concentrations. Methods: Postprandial endotoxemia was measured in twenty four pigs following a porridge meal made with either water (Control), fish oil (FO), vegetable oil (VO) or coconut oil (CO). Blood was collected at 0, 1, 2, 3 and 5 hours postprandial and measured for endotoxin. Furthermore, ex vivo ileum endotoxin transport was assessed using modified Ussing chambers and intestines were treated with either no oil or 12.5% (v/v) VO, FO, cod liver oil (CLO), CO or olive oil (OO). Ex vivo mucosal to serosal endotoxin transport permeability (Papp) was then measured by the addition of fluorescent labeled-lipopolysaccharide. Results: Postprandial serum endotoxin concentrations were increased after a meal rich in saturated fatty acids and decreased with higher n-3 PUFA intake. Compared to the no oil control, fish oil and CLO which are rich in n-3 fatty acids reduced ex vivo endotoxin Papp by 50% (P \u3c 0.05). Contrarily, saturated fatty acids increased the Papp by 60% (P = 0.008). Olive and vegetable oils did not alter intestinal endotoxin Papp. Conclusion: Overall, these results indicate that saturated and n-3 PUFA differentially regulate intestinal epithelial endotoxin transport. This may be associated with fatty acid regulation of intestinal membrane lipid raft mediated permeability

Intestinal integrity, endotoxin transport and detoxification in pigs divergently selected for residual feed intake

Microbes and microbial components potentially impact the performance of pigs through immune stimulation and altered metabolism. These immune modulating factors can include endotoxin from gram negative bacterial outer membrane component, commonly referred to as lipopolysaccharide (LPS). In this study, our objective was to examine the relationship between intestinal barrier integrity, endotoxin and inflammation with feed efficiency (FE), using pig lines divergently selected for residual feed intake (RFI) as a model. Twelve gilts (62 ± 3 kg BW) from the low RFI (LRFI, more efficient) and 12 from the high RFI (HRFI, less efficient) were used. Individual performance data was recorded for 5 wk. At the end of the experimental period, ADFI of LRFI pigs was less (P \u3c 0.001), ADG not different between the 2 lines (P = 0.72) but the G:F of LRFI pigs was greater than for HRFI pigs (P = 0.019). Serum endotoxin concentration (P \u3c 0.01) and the acute phase protein haptoglobin (P \u3c 0.05) were greater in HRFI pigs. Transepithelial resistance of the ileum, transport of fluorescein isothiocyanate labeled-Dextran and-LPS in ileum and colon, as well as tight junction protein mRNA expression in ileum, did not differ between the lines, indicating the 2 lines did not differ in transport characteristics at the intestinal level. Ileum inflammatory markers, myeloperoxidase (P \u3c 0.05) and IL-8 (P \u3c 0.10), were found to be greater in HRFI pigs. Alkaline phosphatase (ALP) activity was significantly increased in the LRFI pigs in ileum and liver tissues and negatively correlated with blood endotoxin (P \u3c 0.05). Lysozyme activity in the liver was not different between the lines; however, the LRFI pigs had a twofold greater lysozyme activity in ileum (P \u3c 0.05). Despite the difference in their activity, ALP or lysozyme mRNA expression was not different between the lines in either tissue. Decreased endotoxin and inflammatory markers and the enhanced activities of antimicrobial enzymes in the LRFI line may not fully explain the difference in the FE between the lines, but they have the potential to prevent the growth potential in HRFI pigs. Further studies are needed to identify the other mechanisms that may contribute to the greater endotoxin and acute phase proteins in the HRFI pigs and the greater FE in the LRFI pigs

Variations in atherosclerosis and remodeling patterns in aorta and carotids

Atherosclerosis is a progressive disease that causes vascular remodeling that can be positive or negative. The evolution of arterial wall thickening and changes in lumen size under current "standard of care" in different arterial beds is unclear. The purpose of this study was to examine arterial remodeling and progression/regression of atherosclerosis in aorta and carotid arteries of individuals at risk for atherosclerosis normalized over a 1-year period. In this study, 28 patients underwent at least 2 black-blood in vivo cardiovascular magnetic resonance (CMR) scans of aorta and carotids over a one-year period (Mean 17.8 ± 7.5 months). Clinical risk profiles for atherosclerosis and medications were documented and patients were followed by their referring physicians under current "standard of care" guidelines. Carotid and aortic wall lumen areas were matched across the time-points from cross-sectional images. The wall area increased by 8.67%, 10.64%, and 13.24% per year (carotid artery, thoracic aorta and abdominal aorta respectively, p < 0.001). The lumen area of the abdominal aorta increased by 4.97% per year (p = 0.002), but the carotid artery and thoracic aorta lumen areas did not change significantly. The use of statin therapy did not change the rate of increase of wall area of carotid artery, thoracic and abdominal aorta, but decreased the rate of change of lumen area of carotid artery (-3.08 ± 11.34 vs. 0.19 ± 12.91 p < 0.05). Results of this study of multiple vascular beds indicated that different vascular locations exhibited varying progression of atherosclerosis and remodeling as monitored by CMR

From imaging to simulation: a framework applied to simulate the blood flow in the carotids

In this work we present a methodology to extract information from medical imaging and use it for hemodynamical simulation in arteries. Based on in-vivo magnetic resonance images (MRI), the velocity of the blood flow has been measured at different positions and times. Also, the anatomy of the vessel has been converted into a volume mesh suitable for numerical modeling. This data has been used to solve computationally the dynamics of the fluid inside the artery in healthy and pathologic cases. As an application, we have developed a computational model within the carotids. The next step in the pipeline will be to extend the simulation to fluidstructure interaction (FSI) to find the parameters in an atherosclerotic plaque that could lead to rupture.Peer Reviewe

From imaging to simulation: a framework applied to simulate the blood flow in the carotids

In this work we present a methodology to extract information from medical imaging and use it for hemodynamical simulation in arteries. Based on in-vivo magnetic resonance images (MRI), the velocity of the blood flow has been measured at different positions and times. Also, the anatomy of the vessel has been converted into a volume mesh suitable for numerical modeling. This data has been used to solve computationally the dynamics of the fluid inside the artery in healthy and pathologic cases. As an application, we have developed a computational model within the carotids. The next step in the pipeline will be to extend the simulation to fluidstructure interaction (FSI) to find the parameters in an atherosclerotic plaque that could lead to rupture.Peer Reviewe