Browsing by Subject "Immunity"
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Item Bacterial Effector HopF2 Suppresses Arabidopsis Immunity by Targeting BAK1(2013-07-19) Zhou, JinggengPseudomonas syringae delivers a plethora of effector proteins into host cells to sabotage host immune responses and physiology to favor infection. We have previously shown that P. syringae pv. tomato DC3000 effector HopF2 suppresses Arabidopsis innate immunity triggered by multiple pathogen-associated molecular patterns (PAMP) at the plasma membrane. We show here that HopF2 possesses distinct mechanisms in the suppression of two branches of PAMP-activated MAP kinase cascades. In contrast to blocking MKK5 in MEKK1-MKK4/5-MPK3/6 cascade, HopF2 targets additional component(s) upstream of MEKK1 in MEKK1-MKK1/2-MPK4 cascade and plasma membrane-localized receptor-like cytoplasmic kinase BIK1 and its homologs. We further show that HopF2 directly targets BAK1, a plasma membrane-localized receptor-like kinase involved in multiple PAMP signaling. The interaction between BAK1 and HopF2 or two additional P. syringae effectors AvrPto and AvrPtoB, was confirmed in vivo and in vitro. Consistent with BAK1 as a physiological target of HopF2, the lethality of overexpression of HopF2 in wild-type Arabidopsis transgenic plants was largely alleviated in bak1 mutant plants. Identification of BAK1 as an additional HopF2 virulence target not only explains HopF2 suppression of multiple PAMP signaling at the plasma membrane, but also supports the notion that pathogen virulence effectors have multiple targets in host cells.Item BTB-Kelch Proteins and TAk1 Kinase N Immune Function(2006-12-19) Liu, Hong-Hsing; Chen, ZhijianBTB-kelch proteins are putative components of E3 ligases with a BTB domain at the N terminus and several kelch repeats at the C terminus. KLHL6 and mKELCH are two members of this family. Conditional ablation of Klhl6 in B cells resulted in mild developmental phenotypes in bone marrow precursors. The number of peripheral B cells was decreased by half, and responded defectively in germinal center formation after antigen stimulations. mKELCH is a novel protein cloned from hearts. Knocked-in LacZ expressed predominantly at muscles and several photosensitive organs. TAK1 is a member of MAPKKK. Deletion of TAK1 prevented the maturation of CD4+ or CD8+ single positive thymocytes, leading to reduction of T cells in peripheral tissues. Thymocytes lacking TAK1 failed to activate NF-κB and JNK, and were prone to apoptosis upon stimulation. All three mouse models have provided important evidences in elucidating biological functions for each protein in vivo.Item Common messenger molecules and cell types demonstrating neuroendocrine-immune interactions in the chicken(Texas A&M University, 2006-08-16) Oubre, Cherie MorganThe aim of this study was to identify common messenger molecules used in both the immune and the neuroendocrine systems in birds, and to shed light on a cell type within the bursa of Fabricius that has historically been postulated as a potential neuroendocrine-immune link, the bursal secretory dendritic-like cells (BSDC). An immunocytochemical approach was used to identify neuroendocrine cell populations in the thymus, pituitary and bursa of Fabricius in the chicken. Molecular confirmation of the neuroendocrine cell marker, chromogranin A (CgA) in the thymus tissue of the chicken was reported. Previously the serine protease inhibitor, ovoinhibitor, was localized in bursal follicles, specifically the cortico-medullary border region. The presence of ovoinhibitor was identified and confirmed in the chicken pituitary by this study. Continued focus on the neuroendocrine-immune interactions in chicken immune tissue narrowed the study around the BSDC population. The BSDC are a component of the stromal, non-lymphoid cellular environment of the bursa of Fabricius and are thought to play a role in B-cell maturation and differentiation. They are located mainly along the cortico-medullary border of the bursal follicles in the same area as the majority of the ovoinhibitor-positive cell population. During attempts to isolate the BSDC population by flow cytometry and laser capture microdissection, a cell culture method was developed that enriched the BSDC population by 10-fold. This enriched population was used to evaluate protein product secretion following lipopolysaccharide (LPS) challenge and compared to in vivo challenge with live Salmonella. For the first time, up-regulation of the pro-inflammatory cytokine IL-12 was documented in the chicken following in vivo challenge. In addition, the gene expression of serine protease inhibitors was markedly decreased in the adherent cell population following LPS stimulation. As a result of this research a novel method for the enrichment of an adherent population, including the BSDC, was developed, providing a valuable tool for the analysis of this population during immune stimulation.Item Effects of dietary supplementation of lactobacillus-based probiotics on growth and gut environment of nursery pigs(2007-12) Rao, Samwel O.; Wilson, Kristopher R.; Kim, Sung W.; Dowd, Scot E.; Brashears, Mindy M.Antibiotic resistance as a result of continuous use has been a thorny issue in pig production. Focus has been directed therefore to use of probiotic supplementation as alternative. Probiotic supplementation has been suggested to benefit the host animal by stimulating appetite, improving intestinal microbial population balance, digestion and improvement of growth performance. Furthermore studies have also suggested a role for probiotics in stimulating the immune system. The objective of this study was to determine the effects of dietary supplementation of Lactobacillus-based probiotics on growth and gut health of newly weaned pigs. Twenty nursery pigs weaned at 21-d of age (6.68 ± 0.27 kg BW) were allotted to 2 treatment groups representing: (1) CON (probiotic-free; corn-soy diet) and (2) PB (test group fed a diet containing 0.2% lactobacillus based probiotics). Pigs were housed individually in metabolism crates and fed the diets for 15-d. At d-15, all pigs were euthanized to collect gut tissues and digesta. There were no differences (P > 0.05) in body weight, ADG, ADFI and FE between the treatments during 15-d period. The numbers of E. coli, Bifidobacteria, Lactobacillus spp., and total anaerobics in colon digesta were altered, although not statistically significant (P > 0.05). Major VFAs were acetate, propionate, isobutyrate, butyrate, isovalerate, and valerate. Acetate accounted for more than 60% of the total VFAs in both treatments while isobutyrate accounted for less that 0.5% of the total VFAs in both treatments. There was no difference (P > 0.05) observed in amount of VFAs in both treatments. There was also no difference (P > 0.05) in the apparent ileal digestibility of amino acids in the diets. Villi height was greater (P < 0.05) in the treatment group as compared to control group. A separate study was conducted to investigate the effects dietary supplementation with Lactobacillus-based probiotics elicits on the immune status of the nursery pig. Differential blood counts were determined on whole blood samples collected on d 13 of the study period. Total RNA was isolated from mesenteric lymph nodes. Gene expression was determined using a 12,000+ pig specific custom microarray, results of which were validated with quantitative PCR. For differential blood counts, there were no differences (P > 0.05) in lymphocyte, neutrophil and monocyte, WBC count, RBC count, hematocrit, and hemoglobin among treatment groups. Microarray results identified significant difference in the expression of 80 genes that were altered by lactobacillus-based probiotics supplementation. Of these genes, nine were comparatively induced (> 2.0 fold) and the rest were comparatively repressed (> 2.0 fold). Functional analyses of these genes identified 25 distinctly enriched functional categories. One of the primary functional categories identified showed significant repression of catalytic activity genes, which represented the majority of repressed transcripts (24.4%). Analyses indicated that lactobacillus based probiotics supplementation altered genes responsible for carbohydrate transport activity, cellular physiology process, defense to pathogens and immune response. In addition, genes related to proteolysis including PRSS2 and CTRB and genes involved in lipid metabolism including LIPC and PLA2G1B were also altered by lactobacillus based probiotic supplementation. Collectively, dietary supplementation of Lactobacillus-based probiotics at 0.2% may have beneficial effects by positively interacting with the intestinal mucosa and the microflora if the length of feeding was increased. The results from these studies indicate that dietary supplementation of Lactobacillus-based probiotics to nursery pig diets may be considered as a nutritional strategy for enhancing intestinal health and possibly positive immune response. Nonetheless, further studies are required to confirm and to elucidate the responsible mechanisms. In addition, the extent to which altered gene expression may affect the animal’s response to actual immune challenge conditions should be determined.Item Exploring the links between stress and innate immune responses in cattle(2010-12) Hulbert, Lindsey E.; Ballou, Michael A.; Carroll, Jeffery A.; Randel, Ronald D.; Welsh, Thomas H.; Galyean, Michael L.Cattle morbidity and mortality are observed more frequently during potential stressful situations, such as weaning, transportation, and commingling. The objectives of this dissertation were to identify intrinsic factors, such as sex-classification and temperament and extrinsic factors such as transportation, feeding strategies and weaning that might influence the stress and innate immune responses of cattle. A sexually dimorphic immune response to endotoxin or corticotropin-releasing hormone (CRH) was observed among Brahman heifers and bull calves. Heifers displayed less sickness behaviors but had greater rectal temperature and circulating tumor-necrosis-factor alpha (TNF-α) response to an in vivo endotoxin challenge than bulls. Heifers also had less of a circulating corticoid response than bulls after CRH and had an acute increase in circulating cytokines that was greater than bulls. Brahman bulls classified as temperamental had less neutrophil activity after transportation than bulls classified as calm. Weaning is a potentially stressful event for calves.. Many innate immune responses in Holstein calves including neutrophilia and decreased phagocytic and oxidative burst capacities were suppressed transiently following weaning. Early weaning calves at 24 d of age rather than at 45 d of age also suppressed neutrophil L-selectin expression. Furthermore, early weaning lightweight calves also suppressed the secretion of TNF-α from whole blood cultures stimulated with LPS. Switching Holstein calves from twice daily to once a daily feeding during the 4th week of life was a mild stressor. There was only a tendency for neutrophilia among the once-fed calves. No other aspects of innate immune responses were acutely suppressed by feeding frequency. These studies indicate that the stress effect of stress on immune responses of cattle is complex. Sex classification, age, and temperament of cattle influence how an animal responds to stress and subsequently, how stress will impact the innate immune system. These studies all indicate that stress can cause an initial suppression of the immune system, but in several instances, the innate immune system had compensatory response, where increased activity after stress is observed.Item Immunomodulatory Effects of Probiotic and Anticoccidial Treatments in Broiler Chickens(2012-10-19) Stringfellow, KendreFour experiments evaluated the impact of probiotic administration on the immune response of broilers vaccinated with a live coccidiosis vaccine. Experiment one showed that probiotic administration increased heterophil and monocyte oxidative burst, and lymphocyte proliferation at multiple time points. In experiment two, probiotic + vaccine increased heterophil and monocyte oxidative burst on d 15 when compared with the negative controls. Overall, vaccine administration alone showed the highest response when compared to all other treatments. In the second trial, all birds were exposed to Eimeria oocysts in the litter and oral gavaged. The results showed that probiotic + vaccine resulted in greater heterophil and monocyte oxidative burst levels on d 14 and 28 when compared to the negative controls. Increases in lymphocyte proliferation were also seen in the probiotic + vaccine and probiotic alone broilers on d 14 among other treatments. In experiment three, heterophil oxidative burst was increased (p <= 0.05) in the vaccine alone group, vaccine with probiotic group, and the ionophore with probiotic group, when compared to the negative control. Monocyte oxidative burst was increased (p <= 0.05) in the vaccine with probiotic group on d 36 and 43, compared to the negative control. Lymphocyte proliferation was greater (p <= 0.05) on d 22 and 36 in the ionophore with probiotic group, when compared to the negative control. Experiment four showed that liver AVBD 2 gene expression elevated (p <= 0.05) in the probiotic + vaccine group relative to the probiotic alone group. Ileum AVBD 2 gene expression was not affected among any of the treatments was evaluated. Liver AVBD 9 was demonstrated to have higher (p <= 0.05) gene expression in the vaccine group when compared to controls. When AVBD 9 gene expression was evaluated in the ileum, a decrease (p <= 0.05) was observed in all treatments compared to the control group. These data suggest that simultaneous administration of probiotics during coccidiosis vaccination or ionophore treatment has the ability to modulate the immune response at varying time points.Item Immunosuppressive dietary n-3 polyunsaturated fatty acids differentially modulate costimulatory regulation of murine CD4+ T-cell function(Texas A&M University, 2005-02-17) Ly, Lan H.Consumption of fish oils (FO) enriched with the n-3 polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), is beneficial to a variety of inflammatory disorders due, in part, to the alteration of membrane composition of T-lymphocytes and other immune cells. We previously observed that down-regulation of proliferation and cytokine synthesis by CD4+ T-cells in mice fed diets rich in n-3 PUFA was dependent on the involvement of CD28, a co-stimulatory molecule necessary for T-cell activation. Since the co-receptor homologues, CD28 and CTLA-4, have opposing effects on T-cell activation, we hypothesized that the balance of costimulatory and downregulatory properties of CD28 and CTLA-4, respectively, would be altered by diet. A significant increase (p<0.05) in CD28 and CTLA-4 surface expression was observed in CD4+ T-cells post-stimulation with phorbol ester and calcium ionophore (PMA/Iono) or anti-CD3 and anti-CD28 (αCD3/CD28) antibodies in all diet groups. A significant increase (p<0.01; 20%) in the number of CD28 molecules was observed in n-3 PUFA vs. CO-fed mice after 48 h of in vitro CD4+ T-cell activation, and both CTLA-4 mRNA transcript and protein levels were upregulated by 50% at 72 h post-activation (p<0.01). Treatment with anti-CTLA-4 mAb in vivo in Mycobacterium bovis (BCG)-vaccinated mice did not alter the suppressive effects of dietary n-3 PUFA on antigen (PPD)-induced lymphocyte proliferation or delayed hypersensitivity reactions. T-cells from both the C57BL/6 and IL-10mice fed dietary n-3 PUFA after 72 h of in vitro stimulation with αCD3/CD28. CD4T-cells from C57BL/6 mice fed DHA produced significantly less IFNγ and IL-10, while CD4T-cells from IL-10Ligation of CD28 upregulates IL-10 receptor (IL-10R) expression on CD4+ T-cells. Therefore, we hypothesized that dietary n-3 PUFA would suppress T-cell function through the effects of IL-10. Surprisingly, the proliferation of purified splenic CD4+ T-cells activated in vitro with αCD3/CD28 was suppressed by dietary n-3 PUFA in both conventional mice (C57BL/6) and IL-10 gene knockout (IL-10(-/-)) mice. Furthermore, IL-10R cell surface expression was significantly down-regulated on CD4+ T-cells from both the C67BL/6 and IL-10(-/-) mice fed dietary n-3 PUFA produced significantly more IFNγ compared to the CO-fed group.Item Physiological consequences of long duration flight in the migratory grasshopper, Melanoplus sanguinipes fabricius(2010-12) Jones, Nathan Thomas; Rankin, Mary Ann Richmond; Hofmann, Hans; Leibold, Mathew; Simpson, Beryl; Zakon, HaroldThis study sought to examine the physiological correlates of migratory flight performance the North American migratory grasshopper Melanoplus sanguinipes Fabricius (Orthoptera: Acrididae) with a focus on mechanisms of resource allocation, the dynamics of hemolymph proteins, their interface with immune function, and the mechanism of flight-enhanced oogenesis. The performance of long duration flights has been shown previously to be of reproductive benefit to females who make them. Examination of possible mechanisms of resource compensation for the costs of flight showed no significant increase in either feeding, mating or digestion in females who performed long duration flight. A comparison of two populations of M. sanguinipes from Arizona and Colorado showed significant variation in body size, diapause regulation as well as internal and external morphology. The two populations did not differ in taxonomic characters or in short sequences of genomic and mitochondrial DNA. The follicle cell epithelium of ovaries from M. sanguinipes was examined for its relationship to juvenile hormone III (JH III). JH III induces patency in vitro in intercellular spaces of M. sanguinipes follicular epithelium as well as the characteristic apical endocytosis at the follicle cell oocyte interface. Exogenous JH III treatment of females on day 7 in lieu of flight reduced the threshold for induction of patency to 10-7 M JH III from 10-5 M JH III. These results indicate that JH III can act as a prime to the pump of oogenesis. An HPLC/LC-MS peptidomic survey of the hemolymph of M. sanguinipes following flight performance showed the presence of and changes in serine protease inhibitors. These peptides regulate numerous protease cascades involved in reproduction and immunity which suggested that flight might have a more broad impact than previously thought. Males who performed these flights showed a higher probability of surviving a bacterial challenge. The duration of flight performance was positively correlated in males with increases in titers of the hemolymph lipoproteins apolipophorin I and hexemerin. The exchangeable apolipophorin III showed no variation in correlation with flight. Females were not affected by flight performance in terms of hemolymph protein titers or the probability of surviving a bacterial challenge. These results suggest that the lipid transport system plays an important role in the immune response of this insect.Item The effects of copper and zinc source on performance, morbidity, and immune response of stressed heifers(Texas Tech University, 2000-08) Salyer, Greg BrandonThree experiments were conducted to compare Cu and Zn sources. Experiment 1 evaluated the effects of various Cu and Zn sources and levels on ruminal in vitro dry matter disappearance (IVDMD) of starch and cellulose substrates, and Experiments 2 and 3 used stressed (marketing and transport) heifers to study the effects of Cu and Zn source on performance, morbidity, and immune response.Item Women’s psychology of disease avoidance(2009-12) Fleischman, Diana Santos; Buss, David M.The following will explore how physiological states influence measures of disease avoidance. The first two studies investigate the psychological effects of progesterone and immunomodulation to behaviors relevant to disease avoidance. In the first study, I investigated the effect of menstrual phase on disgust sensitivity and obsessive-compulsive disorder symptomology finding that in periods of high estimated progesterone women show increased disgust sensitivity and OCD symptomology. In the second study I used salivary assays to measure progesterone and correlate progesterone level with a variety of measures of disease avoidance. In the final study I investigated how sexual arousal, a motivational state that moves an organism closer to potential disease vectors and disgust, an emotion that motivates organisms away from disease vectors, mitigate one another using image ratings and an objective measure of physiological sexual arousal, vaginal photoplethysmography.Item Yeast supplementation alters the performance and health of cattle during the receiving period(2011-05) Finck, Derek N.; Johnson, Bradley J.; Rathmann, Ryan J.; Beckett, Jonathan L.The objective of this experiment was to determine the effect of yeast supplements on performance and health of steers during the receiving period. Weaned crossbred steers (n = 184; initial BW = 203 ± 1 kg) were blocked by BW and randomly assigned to pen (4 pens/block; 5-6 hd/pen). Pens within a block were randomly assigned to one of four treatments (9 pens/treatment): 1) control (CON; no yeast additive), 2) live yeast (LY; 5 g.hd-1.d-1 BIOSAF, Lesaffre Feed Additives, Milwaukee, WI), 3) yeast cell wall (YCW; 5 g.hd-1.d-1 Pronady 500, Lesaffre Feed Additives), 4) live yeast + yeast cell wall (LY+YCW; 5 g.hd-1.d-1 live yeast and 5 g.hd-1.d-1 yeast cell wall). Daily DMI was recorded and individual BW was collected every 14 d for 56 d. Data were analyzed using a randomized complete block design using the fixed effect of treatment and random effect of block (SAS Inst. Inc., Cary, NC). A subset of 24 steers was utilized after 38 d on feed to determine the effect of yeast supplementation on the response to a lipopolysaccharide (LPS) challenge. Calves were fitted with jugular catheters and indwelling rectal temperature measuring devices that measured rectal temperature at 1-min intervals, and were moved into individual stanchions. On d 39, blood samples were collected at 30-min intervals from -2 to 8 h and then at 24 h relative to administration of LPS (0.5 μg/kg BW) at 0 h. Blood samples were used to determine serum interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), cortisol concentrations, and neutrophil:lymphocyte (N:L) ratios. Data were subjected to analysis of variance specific for repeated measures using Statview (SAS Inst. Inc.) with sources of variation including treatment, time and their interactions. Specific time point comparisons within treatment group were conducted using a Paired t-test to compare pre-challenge values with specific time points post-challenge. Steers receiving LY or YCW showed a 7% numerical increase (P = 0.59) in ADG and a 7.7 ± 4.7 kg increase in BW at d 56. Cumulative DMI increased (P = 0.05) for the LY, YCW, and LY+YCW treatments compared to CON (5.47, 6.02, 5.96, and 5.89 kg/d; CON, LY, YCW, and LY+YCW, respectively). Steer morbidity and mortality were not affected by yeast supplementation (P ≥ 0.10). In response to LPS challenge, basal RT prior to LPS tended (P ≤ 0.06) to differ among groups with CON calves having higher RT compared to LY+YCW (P ≤ 0.01) and LY (P ≤ 0.04) calves. After the LPS challenge, RT remained higher in the CON calves compared to other treatments (P ≤ 0.05). By 10 h post-LPS, RT were still greater (P ≤ 0.05) in CON calves compared to all other calves, and remained numerically greater throughout the study. Serum cortisol increased in all groups post-LPS with peak concentrations observed at 1 h. Peak cortisol concentrations were 26.5 ng/mL greater (P ≤ 0.04) in CON calves compared to LY+YCW calves. Interferon-gamma (IFN-γ) concentrations tended (P ≤ 0.06) to be greater in CON calves compared to YCW calves prior to LPS exposure. Collectively, these data indicated that the use of yeast additives increased total feed consumed by the steers during the first 56 d of the feeding period, and improved health, thus allowing for enhanced performance.