Browsing by Subject "Lipopolysaccharide"
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Item Age-Related Effects on Markers of Inflammation and Cartilage Metabolism in Response to an Intra-Articular Lipopolysaccharide Challenge(2014-11-25) Kahn, Meredith KEighteen Quarter Horses were utilized in a randomized complete design for a 28 d experiment to evaluate age-related effects on inflammation and cartilage turnover after induction of a single inflammatory insult using lipopolysaccharide (LPS). Horses were grouped by age, with yearlings (yearling; n = 3 males, n = 3 females), 2 to 3 yr olds (2/3; n = 2 males, n = 4 females), and mature 5 to 8 yr olds (mature; n = 2 males, n = 4 females). On d 0, all horses were housed individually and fed diets that met or exceeded NRC (2007) requirements. On d 14, horses were challenged with an intra-articular injection of LPS. Carpal joints were randomly assigned to receive 0.5 ng LPS solution obtained from E. coli O55:B5, or 0.8mL sterile lactated Ringer?s solution as a contralateral control. Synovial fluid was collected prior to LPS injection at pre-injection h 0 (PIH 0) and 6, 12, 24, 168, and 336 h post-injection. Samples were later analyzed using commercial ELISA kits for prostaglandin E2 (PGE2), collagenase cleavage neoepitope (C2C), and carboxypropeptide of type II collagen (CPII). Heart rate (HR), respiratory rate (RR), and rectal temperature (RT) were monitored over the first 24 h and carpal circumference and surface temperature were recorded with additional measurements at 168 and 336 h. Data were analyzed using PROC MIXED procedure of SAS. Values for RT, HR, and RR were within normal range. HR and RT were influenced by age (P < 0.01), while RR was unaffected by age (P ? 0.21). Joint circumference was not influenced by age (P = 0.84), but circumference and surface temperature increased (P < 0.01) over time across all age groups. Synovial PGE2 concentrations tended (P = 0.09) to be influenced by age with yearlings having lower (P = 0.03) concentrations than mature horses. Synovial C2C concentrations were affected by age with yearlings and 2/3 yr olds having lower (P < 0.01) concentrations than mature horses. Concentrations of synovial CPII were influenced by age with yearlings and 2/3 yr old having lower (P ? 0.02) concentrations than mature horses. Ratios of CPII:C2C were influenced by age with mature and 2/3 yr old horses having increased (P < 0.01) values compared to yearlings. These results indicate that inflammation and corresponding cartilage turnover in response to LPS administration vary with age.Item Concerning Brucella LPS: genetic analysis and role in host- agent interaction(Texas A&M University, 2006-10-30) Turse, Joshua EdwardB rucella lipopolysaccharide is an important component of virulence in brucellosis. Recent research in macrophage models has shown that Brucella LPS does not behave like classical LPS by stimulating potent inflammatory responses. The central hypothesis of this work is that O-antigen is dynamic signaling molecular and participates in complex interactions with the host to promote productive infection. A corollary to this is that the host environment is dynamic, and Brucella has evolved mechanisms to cope with changing environments. In an effort to understand the contribution of Brucella LPS to virulence and pathogenesis, the function of a metabolic locus important in the synthesis of LPS has been demonstrated and complemented. The spontaneous loss of LPS expression has been characterized. Contribution of LPS to acquisition of the host environment in tissue culture and mouse models has been explored. This work demonstrated that genes outside the O-antigen biosynthesis ( manBA) cluster contribute to LPS biosynthesis. Further high frequency mutation involving manBA is partly responsible for observed dissociation of Brucella strains. Finally, work herein attempts to look at the role of LPS in acquisition of the host environment and shows that LPS is important for recruiting particular cell populations within a host model of brucellosis.Item Evaluation of Conjugated Linoleic Acid Supplementation on Markers of Joint Inflammation and Cartilage Metabolism in Young Horses Challenged with Lipopolysaccharide(2014-12-05) Bradbery, Amanda NicoleSeventeen yearling Quarter Horses were used in a randomized complete block design for a 56 d trial to determine ability of dietary conjugated linoleic acid (CLA) to reach circulating levels in plasma and mitigate joint inflammation and cartilage turnover. Horses were blocked by age, sex and BW and randomly assigned to treatments consisting of a commercial concentrate offered at 1% BW (as-fed) supplemented with either 1% soybean oil (CON; n = 6), 0.5% soybean oil and 0.5% CLA (LOW; n = 5; Lutalin?, BASF Corp.), or 1% CLA (HIGH; n = 6; 55% purity) top-dressed daily. Horses were fed individually every 12 h and offered 1% BW daily (as-fed) coastal bermudagrass (Cynodon dactylon) hay. This study was separated into two phases: phase 1 determined incorporation of CLA to circulating levels in plasma; phase 2 evaluated the potential of CLA to mitigate induced intra-articular inflammation and cartilage metabolism stimulated by lipopolysaccharide (LPS). Phase 1 comprised the first 41 d. Phase 2 began on d 42 and extended to d 56. Weekly, beginning at d 0, physical growth measurements were recorded and blood samples were collected and analyzed for fatty acid concentrations. On d 42, an LPS challenge was conducted. Carpal joints within each horse were randomly assigned to receive intra-articular injections of 0.5 ng LPS derived from Escherichia coli 055:B5 or sterile lactated Ringer?s solution as a contralateral control. Synovial fluid samples were obtained via arthrocentesis at pre-injection h 0 and 6, 12, 24, 168 and 336 h post-injection, and subsequently analyzed by ELISA for prostaglandin E2 (PGE2), carboxypeptide of type II collagen (CPII), and collagenase cleavage neopeptide (C2C). Vitals were monitored at 0, 6, 12 and 24 h; and carpal circumference and surface temperatures were also recorded. All data were analyzed using PROC MIXED procedure of SAS. All physical measurements increased (P < 0.01) over time with no influence of CLA supplementation. Isomers of CLA were detectable in plasma by d 14, and HIGH horses had greatest concentrations (P < 0.04). Horses fed CON had undetectable levels of CLA. Arachidonic acid levels were lower (P < 0.06) in HIGH horses compared to both LOW and CON. Vitals were not different across dietary treatments (P > 0.13) and remained within normal. Synovial PGE2 was not affected by dietary treatment (P = 0.15). Synovial C2C responded to dietary treatment (P = 0.05) with HIGH horses having lower C2C than LOW. There was an effect (P < 0.01) of time with C2C values peaking between h 12 and 24, and decreasing by h 336. Levels of CPII tended to be influenced by dietary treatment (P = 0.10) with LOW horses having greater CPII compared to CON, and HIGH horses were intermediate with no difference from CON or LOW. Regardless of diet, CPII increased to h 24 (P < 0.01) and decreased to h 336. In conclusion, dietary CLA reached circulating levels in plasma prior to the LPS challenge. Dietary CLA supplementation did not influence PGE2; however, horses receiving CLA had lesser C2C and greater CPII, indicating less degradation and greater synthesis of cartilage in response to an acute inflammatory condition.Item Membrane remodeling in epsilon proteobacteria and its impact on pathogenesis(2012-05) Cullen, Thomas Wilson; Trent, Michael Stephen; Whiteley, Marvin; Harshey, Rasika M.; Stevens, Scott W.; O'Halloran, Terry J.Bacterial pathogens assemble complex surface structures in an attempt to circumvent host immune detection. A great example is the glycolipid known as lipopolysaccharide or lipooligosaccharide (LPS), the major surface molecule in nearly all gram-negative organisms. LPS is anchored to the bacterial cell surface by a anionic hydrophobic lipid known as lipid A, the major agonist of the mammalian TLR4-MD2 receptor and likely target for cationic antimicrobial peptides (CAMPs) secreted by host cells (i.e. defensins). In this work we investigate LPS modification machinery in related ε-proteobacteria, Helicobacter pylori and Campylobacter jejuni, two important human pathogens, and demonstrate that enzymes involved in LPS modification not only play a role in evasion of host defenses but also an unexpected role in bacterial locomotion. More specifically, we identify the enzyme responsible for 4'-dephosphorylation of H. pylori lipid A, LpxF. Demonstrating that lipid A depohsphorylation at the 1 and 4'-positions by LpxE and LpxF, respectively, are the primary mechanisms used by H. pylori for CAMP resistance, contribute to attenuated TRL4-MD2 activation and are required for colonization of a the gastric mucosa in murine host. Similarly in C. jejuni, we identify an enzyme, EptC, responsible for modification of lipid A at both the 1 and 4'-positions with phosphoethanolamine (pEtN), also required for CAMP resistance in this organism. Suprisingly, EptC was found to serve a dual role in modifying not only lipid A with pEtN but also the flagellar rod protein FlgG at residue Thr75, required for motility and efficient flagella production. This work links membrane biogenesis with flagella assembly, both shown to be required for colonization of a host and adds to a growing list of post-translational modifications found in prokaryotes. Understanding how pathogens evade immune detection, interphase with the surrounding environment and assemble major surface features is key in the development of novel treatments and vaccines.