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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Allergen-Induced Chemokine Release from the Bronchial Epithelium: A Novel Lysosomal Release Mechanism

Webb, Mark 14 October 2014 (has links)
No description available.
62

The Role of CCR5 in Protection Against Histoplasma capsulatum Infection

Kroetz, Danielle N. 20 September 2011 (has links)
No description available.
63

CXCL12/CXCR4 signaling in mesocorticolimbic reward pathways: relevance to cocaine reinforcement and relapse

Kim, Jae Kyun January 2016 (has links)
The role of chemokines as chemotactic cytokines and their functions in the immune system and related pathologies are well defined. Recently, strong evidence supporting the hypothesis that chemokines can act as modulators of neuronal activity and influence neurotransmission has been reported. The chemokine CXCL12 is constitutively expressed in adult brain and expression of CXCL12 and its cognate receptor CXCR4 have been reported in regions of rat brain that construct dopamine (DA) and glutamate (GLU) pathways such as ventral tegmental area (VTA), substantia nigra (SN), and nucleus accumbens (NAc). In the central nervous system (CNS), activation of CXCR4 on dopaminergic neurons and astrocytes initiate cascade of events that leads to DA and GLU release and influence synaptic transmission. In vivo, intracerebroventricular (ICV) CXCL12 has been shown to potentiate cocaine-induced locomotor activity. Based on these evidences, the studies, as outlined in this dissertation, aimed to expand understanding of how CXCL12/CXCR4 interaction can affect cocaine-induced behavior and reinforcement, with special focus on mechanisms involving GLU. We first evaluated involvement of CXCR4 activation by CXCL12 on cocaine-induced locomotor activity using a selective CXCR4 antagonist AMD3100. Results demonstrated that AMD3100 (5, 10 mg/kg, IP) pretreatment dose-dependently attenuated cocaine-induced locomotor activity without affecting the baseline activity. Thereafter, effects of AMD3100 on cocaine’s reinforcing efficacy were tested using a biased conditioned place preference (CPP) paradigm. In all CPP experiments, saline pretreated controls established a significant preference for the cocaine-paired context following four pairings with cocaine (10 mg/kg, IP). Rats pretreated with 2.5 and 5 mg/kg AMD3100 prior to each pairing session showed significantly lower preference for the cocaine-paired side, whereas rats pretreated with 1 mg/kg AMD3100 showed similar preference for the cocaine-paired side as the saline controls when tested in the absence of the drug. Rats pretreated with AMD3100 (5 mg/kg, IP) just once prior to testing showed significantly lower preference for the cocaine-paired side. These results demonstrate that CXCR4 antagonism reduces development and expression of cocaine-induced CPP. Intravenous cocaine self-administration (SA) was performed to examine the effects of AMD3100 on the acquisition of cocaine-taking behavior and reinstatement to cocaine-seeking. Acquisition of cocaine SA was studied using three doses of cocaine (0.375, 0.5, 0.75 mg/kg/infusion) on a fixed-ratio 1 (FR-1) schedule of reinforcement. Two doses of AMD3100 (5, 10 mg/kg, IP) were tested. In all SA experiments, saline pretreated controls readily acquired cocaine self-administration. The lower and higher AMD3100 decreased the number of reinforcers earned during the two hour sessions compared to saline controls when tested against acquisition of 0.375 and 0.5 mg/kg/infusion cocaine. However, when tested against the 0.75 mg/kg/infusion cocaine, only 10 mg/kg of AMD3100 resulted in reduction in responding, but not the lower dose. When a dose response curve was plotted using all doses of cocaine and AMD3100 tested, the effects of AMD3100 were represented by a significant downward shift of the dose response curve. Effects of AMD3100 on cocaine-seeking were evaluated using the reinstatement model, in which rats that were extinguished from self-administration of 0.5 mg/kg/infusion cocaine underwent reinstatement testing with cue or cue + drug presentation. A compound cue (light and tone stimulus), that was used during the acquisition training, and submaximal dose of cocaine (5mg/kg, IP) were used. In both reinstatement conditions, rats pretreated with saline reinstated following the presentation of cue or cue + drug prime. Rats pretreated with AMD3100, 30 minutes prior to reinstatement session, showed significantly lower number of lever presses indicating drug-seeking was not as robust compared to the saline pretreated controls. Following the observations that cocaine-induced behaviors may be partially mediated by CXCL12/CXCR4 interaction, neurochemical changes were examined to elucidate the underlying mechanisms. CXCR4 immunoreactivity in prefrontal cortex (PFC) following withdrawal from 7 days of repeated cocaine (15 mg/kg, IP) was evaluated. Although positive CXCR4 immunoreactivity was observed in PFC, there were no significant differences in the intensity of CXCR4 expression compared to the saline treated controls at acute (2 hours, 2 and 10 days) or protracted (30 days) withdrawal time points. In contrast, CXCL12 protein levels in PFC and NAc were negatively influenced after protracted withdrawal from 7 days of repeated cocaine (15 mg/kg, IP) administration. Following assessment of regional expression of CXCR4, cellular expression was evaluated using triple labeling immunohistochemistry which revealed the positive CXCR4-immunoreactivity on cells staining positively for vesicular glutamate transporter 1 (vGlut1) and glial fibrillary acidic protein (GFAP) showing that the glutamatergic neurons and astrocytes in the PFC express CXCR4. To assess the effects of CXCL12 on GLU transmission, microdialysis of NAc was performed. Following unilateral injection of 50 ng CXCL12 into the lateral ventricle, increase in extracellular GLU was observed. In a follow up study, AMD3100 pretreatment (10 mg/kg, IP) attenuated cocaine-induced increase in extracellular GLU in the NAc. Since the glutamate transporter subtype-1 (GLT-1) is a major regulator of extracellular GLU and upregulation of GLT-1 expression and function has been shown to attenuate reinstatement to cocaine-seeking, its expression was evaluated using immunoblot analysis of the NAc and PFC of rats that self-administered cocaine. The results revealed that AMD3100 (10 mg/k, IP; daily injection 30 min prior to SA session) pretreatment upregulated GLT-1 levels in the NAc but not PFC. In summary, results of the present study show that CXCL12/CXCR4 interaction may modulate cocaine-induced behavioral effects including reinforcement and reinstatement to cocaine-seeking. Neurochemical assessments revealed the presence of CXCR4-expressing glutamatergic neurons in the PFC and AMD3100-induced up-regulation of GLT-1. Most importantly, we provided direct evidence of CXCL12/CXCR4 mediated GLU transmission in NAc. Together, these results expand our understanding of chemokine’s role as neuromodulators and identify CXCR4 as a novel target for development of new pharmacotherapies for the treatment of cocaine addiction. / Pharmacology
64

Study of expression of systems CXCR4-CXCL12/SDF-1, CCR7-CCL21 and Ki-67 in the oral squamous cell carcinoma and their association with clinicopathological factors,nodal metastases and survival / Estudo da imunoexpressÃo dos sistemas CXCR4-CXCL12/SDF-1, CCR7-CCL21 e Ki-67 no carcinoma de cÃlulas escamosas oral e sua associaÃÃo com indicadores clÃnicopatolÃgicos, metÃstase linfonodal e sobrevida

GalylÃia Menezes Cavalcante 16 July 2013 (has links)
Chemokines are responsible for the directed migration of leukocyte chemotactic cytokines, coordinating cell movement during inflammation and the transport of hematopoietic cells. In addition to leukocytes, chemokine receptors are also found in neoplastic cells and tumors associated with stromal cells. Among chemokines, and the CXCR4/CXCL12 CCR7/CCL21 systems have been shown the involvement of lymph node metastases or distant metastases in different cancers. Thus, aim of this study was to evaluate the expression of CXCR4, CXCL12, CCR7, CCL21 and Ki-67 in oral squamous cell carcinoma (SCC) and to correlate these markers with clinicopathological indicators, lymph node metastasis and survival. We conducted a survey of reports and paraffin blocks of excisional biopsies of patients with SCC treated at the Hospital Haroldo JuaÃaba (2001-2009). Data on anatomic location of the lesion, sex, age, patient survival, degree of histological differentiation of the tumor, tumor stage and presence or absence of lymph node metastasis, lymphovascular and perineural invasion, nuclear grade and depth of invasion were collected. For immunohistochemical analysis, followed by the technique of streptavidin-biotin-peroxidase using the anti-CXCR4, anti-CXCL12, anti-CCR7, anti-CCL21 and Ki-67 antibody. Histological sections were photomicrographed in 10 fields chosen randomly and measured for the number of labeled tumor cells and determined the percentage of each labeling antibody. The marking of CXCR4 was detected in the cytoplasm and nucleus, CXCL12, CCR7 and CCL21 were only cytoplasmic, their expression was observed in 18 (60%) 8 (22.66%) 16 (53.3%) and 3 (12%) cases, respectively. We found a significant positive association between lymphovascular invasion and immunostaining of CXCR4 (p = 0.007) and CCR7 (P = 0.01) and among these cases metastasis was present in 62.5% and 37.5%, respectively. When in combination with Ki67, we found a significant positive correlation between CXCR4 (p = 0.0086), CXCL12 (p = 0.036) and CCR7 (p = 0:04). Among patients CXCR4 + over 111 months, only 38.4% were alive (p = 0.845), whereas both patients CCR7 + (p = 0.398) as well as CXCR4 +, and CCR7 + (p = 0.441) after 62 months, everyone had already died. We conclude that these chemokines are associated with lymphovascular invasion and cell proliferation, perhaps favoring the development of metastasis and poor prognosis. / As quimiocinas sÃo citocinas quimiotÃticas responsÃveis pela migraÃÃo direcionada de leucÃcitos, coordenando o movimento celular durante a inflamaÃÃo e o transporte de cÃlulas hematopoiÃticas. AlÃm dos leucÃcitos, os receptores de quimiocinas tambÃm sÃo encontrados em cÃlulas neoplÃsicas e em tumores associados com cÃlulas estromais. Dentre as quimiocinas, os sistemas CXCR4/CXCL12 e CCR7/CCL21 tÃm sido demonstrado no envolvimento de metÃstases linfonodais ou à distÃncia em diferentes tipos de cÃncer. Dessa forma, foi objetivo desse trabalho avaliar a expressÃo de CXCR4, CXCL12, CCR7, CCL21 e Ki-67 em carcinoma de cÃlulas escamosas orais (CEC) e correlacionar estes marcadores com indicadores clÃnicopatolÃgicos, metÃstase linfonodal e sobrevida. Realizou-se um levantamento de laudos e blocos parafinados de biopsias excisionais de pacientes portadores de CEC tratados no Hospital Haroldo JuaÃaba (2001 a 2009). Foram coletados dados sobre localizaÃÃo anatÃmica da lesÃo, sexo, idade, sobrevida do paciente, grau de diferenciaÃÃo histopatolÃgica do tumor, estadiamento tumoral e presenÃa ou ausÃncia de metÃstase linfonodal, invasÃo linfovascular e perineural, grau nuclear e profundidade de invasÃo. Para reaÃÃo de imunohistoquÃmica, seguiu-se a tÃcnica da estreptavidina-biotina-peroxidase, utilizando os anticorpos anti-CXCR4, anti-CXCL12, anti-CCR7, anti-CCL21 e Ki-67. As secÃÃes histolÃgicas foram fotomicrografadas em 10 campos escolhidos aleatoriamente e quantificadas quanto ao nÃmero de cÃlulas tumorais marcadas e determinado o percentual de marcaÃÃo de cada anticorpo. A marcaÃÃo de CXCR4 foi detectada em citoplasma e nÃcleo, CXCL12, CCR7 e CCL21 tiveram marcaÃÃo apenas citoplasmÃtica, sendo observada suas expressÃes em 18 (60%), 8 (22,66%), 16 (53,3%) e 3 (12%) casos, respectivamente. Encontrou-se uma associaÃÃo significativa positiva entre a invasÃo linfovascular e a imunomarcaÃÃo do CXCR4 (p=0.007) e CCR7 (p=0.01) e dentre esses casos a metÃstase esteve presente em 62,5% e 37,5%, respectivamente. Quando em associaÃÃo com o Ki67, encontrou-se uma correlaÃÃo positiva significante entre o CXCR4 (p=0.0086), CXCL12 (p=0.036) e CCR7 (p=0.04). Dentre os pacientes CXCR4+, ao longo de 111 meses, apenas 38,4% estavam vivos (p=0.845), ao passo que tanto para pacientes CCR7+ (p = 0.398), quanto CXCR4+ e CCR7+ (p = 0.441), apÃs 62 meses, todos haviam ido a Ãbito. Conclui-se que essas quimiocinas estÃo associadas com a invasÃo linfovascular e proliferaÃÃo celular, talvez favorecendo o desenvolvimento de metÃstases e um pior prognÃstico.
65

Function of M4 protein in vitro and in vivo

Wang, Xuan January 2013 (has links)
Herpesviruses are ubiquitous in both humans and animals and can cause life-threatening disease. The discovery of murine gammaherpesvirus 68 (MHV-68), which has many similarities in genome and pathogenesis as the human pathogens Epstein-Barr virus and Kaposi’s sarcoma-associated herpesvirus, provides a model for further investigation of the pathogenesis of gammaherpesviruses. The M4 gene was found to be at the left end region of MHV-68 genome. The presence of the M4 protein is required during the early establishment of MHV-68 latency. However, the function of M4 protein remains unclear. The aim of this project was to investigate the function of the M4 protein in vitro and during infection. By using an ELISA, the recombinant M4 protein was shown to bind several Cxc-chemokines and stop the interaction between Cxcl4 and GAGs. The role of M4 protein during MHV-68 lytic infection and in the early establishment of latency was studied by comparing the pathogenesis of virus which does not express M4 (M4stop) and wild type virus (WT). Compared to WT infection, this study found that M4stop was decreased in the lungs at day 8 post infection (p.i.). At the same time point, the viral loads were higher in M4stop infected spleens, which was accompanied by increased expression of the CD4+ T cell activation marker PD-1 and the macrophage activation marker CD69. However, at day 14 p.i., the M4stop infected spleens had lower viral loads, and the expression of CD69 was decreased on CD4+, CD8+ T cells, B cells and macrophages. Furthermore, gene expression PCR arrays were used to investigate how cellular activation and inflammation were transcriptionally regulated. It has been found that the transcription of several genes, which are involved in germinal centre development, was lower in the spleens of WT infected mice at day 12 and 14 p.i. compared to day 10 p.i. of WT infection, as well as day 12 and 14 p.i. of M4stop infection. In addition, the percentage of germinal centre B cells was found to be higher in spleens infected with M4stop at day 10 p.i.. However, there was no difference in percentages of TFH and plasma cells in the spleens. Finally, in order to understand the role of IFN-γ in control of infection in M4stop infected mice, IFN-γR-/- mice were infected with M4stop and WT. Although there were differences in pathogenesis between WT and M4Stop virus infected IFN-γR-/- mice, there was no clear evidence that M4 function is involved in inhibiting IFN-γ pathways. In this study, we found M4 can disturb the interaction of chemokine and GAGs and might delay virus trafficking to the spleen, which could lead to a reduction of cellular activation. M4 may also impair the development of germinal centres at the beginning of latent infection in the spleens.
66

Modulation systemischer Chemokinspiegel durch rekombinantes Interferon-beta bei Patienten mit multipler Sklerose / Modulation of systemic chemokine levels by recombinant interferon-beta in patients with multiple sclerosis

Merzyn, Cornelia January 2008 (has links) (PDF)
Multiple Sklerose (MS) ist eine chronisch-entzündliche Erkrankung des Zentralen Nervensystems mit deutlich ausgeprägten Autoimmunphänomenen. Das derzeit meistverwendete Therapeutikum zur Sekundärprophylaxe von Krankheitsschüben ist rekombinantes Interferon-β (IFN-β). Wirk- und Nebenwirkungsmechanismen des Medikaments werden bisher nur partiell verstanden. In der Pathogenese der MS spielt eine Familie chemotaktisch wirksamer Zytokine, der Chemokine, eine entscheidende Rolle. Ziel dieser Studie war zu untersuchen, ob IFN-β die systemischen Konzentrationen der Pathogenese-relevanten Chemokine CXCL10, CCL2 und außerdem des endogenen Pyrogens IL-6 verändert, und ob diese Veränderungen mit dem Auftreten grippeartiger Nebenwirkungen korrelieren. Zu diesem Zweck wurden bei 37 Patienten mit schubförmiger MS zu drei Zeitpunkten – vor sowie 6 und 24 Stunden nach der Applikation von IFN-β – die genannten Botenstoffe im Blut bestimmt. Parallel wurden subjektiv empfundene grippeartige Nebenwirkungen mit Hilfe eines standardisierten Fragebogens abgefragt, und die Körperkerntemperatur wurde gemessen. Als Kontrollen dienten gesunde Probanden, derzeit nicht immunmodulatorisch behandelte MS-Patienten und MS-Patienten unter Therapie mit Glatirameracetat. Nur bei den mit IFN-β behandelten Patienten zeigte sich nach 6 Stunden ein signifikanter transienter Anstieg der Konzentrationen von CXCL10, CCL2. Der Anstieg der Chemokinkonzentrationen korrelierte mit einem transienten IL-6-Anstieg und dem Auftreten grippeartiger Nebenwirkungen. Chemokine, unter denen sich zahlreiche starke endogene Pyrogene befinden, könnten somit für die häufig zu beobachtenden grippeartigen Nebenwirkungen mit verantwortlich sein. Die Ergebnisse werfen die weiterführende Frage auf, ob die beobachtete Chemokininduktion auch relevant für den therapeutischen Effekt von IFN- ist. Ob Chemokine sich erfolgreich als Biomarker zur Prädiktion des Therapieerfolgs einsetzen lassen, wird derzeit in einem weiterführenden Projekt untersucht. / Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system with clear autoimmune phenomena. Recombinant Interferon-β (IFN-β) is currently the most widely used treatment to prevent relapses. The mechanisms and side effects of the drug are only partially understood. A family of chemotactical active cytokines, the chemokines, play a decisive role in the pathogenesis of MS. The aim of this study was to examine if IFN-β alters the systemic concentrations of CXCL10 and CCL2, two chemokines that are relevant in the pathogenesis, and of IL-6, an endogenous pyrogen. A further aim was to discover whether these concentrations correlate with the appearance of flu-like symptoms, a common adverse effect of IFN-β. 37 patients with relapsing-remitting MS were tested three times to measure the chemokine concentrations in their blood – prior to IFN-β application, and again 6 and 24 hours after application. Concurrently, the occurrence of flu-like symptoms was recorded with the help of a standardized questionnaire and through body temperature measurements. The control groups consisted of healthy subjects, MS patients not receiving any treatment, and MS patients treated with glatiramer acetate. After 6 hours, only the MS patients treated with IFN-β showed a significant transient elevation in the concentrations of CXCL10 and CCL2. This elevation correlated with a transient increase in the IL-6 concentration and the appearance of flu-like symptoms. Among the chemokines there are many strong endogenous pyrogens, which might be responsible for the commonly observed, flu-like side effects of IFN-β. The results raise the question of whether the observed induction of chemokines is also relevant for the therapeutic effect of IFN-β. Whether chemokines can be used as biomarkers to predict therapeutic success is currently being explored in ongoing work built upon this study.
67

Einfluss der Langzeittherapie mit dem Endocannabinoid-Rezeptorblocker Rimonabant auf Thrombozytenaktivierung und proinflammatorische Chemokine bei Diabetes / Influence of long-term therapy with cannabinoid receptor-1 antagonist Rimonabant on thrombocytes and proinflammatoric chemokines in diabetes

Neumüller, Jutta January 2010 (has links) (PDF)
Die Volkskrankheit Adipositas zieht eine Reihe von kostenträchtigen Komplikationen mit sich wie z. B. Diabetes mellitus Typ 2 und kardiovaskuläre Erkrankungen. Der Endocannabinoidblocker Rimonabant ist hierbei ein viel versprechendes Medikament, mit dem nicht nur die Adipositas an sich, sondern zusätzlich auch ihre weit reichenden Komplikationen im kardiovaskulären Bereich reduziert werden können. Im Rahmen der vorliegenden Arbeit konnten an Hand 6 Monate alter diabetischer Ratten, welche für 10 Wochen mit Rimonabant behandelt wurden, aufgezeigt werden, dass Rimonabant auf verschiedenste Weise die Initialphase der Atherogenese positiv beeinflusst. Zum einen konnte die Anzahl der zirkulierenden Monozyten signifikant vermindert und auch die für die initiale Rekrutierung von Thrombozyten und Monozyten wichtigen Chemokine RANTES und MCP-1 reduziert werden. Zum anderen zeigten sich positive Effekte auf das Lipidprofil der Probanden. Ein besonderes Augenmerk lag auf dem Aktivitätszustand der Thrombozyten: Mit Rimonabant wurde sowohl die thrombozytäre Aktivierung minimiert als auch ein positiver Einfluss auf die Thrombozytenadhäsion und -aggregation bestätigt. Folglich reduziert Rimonabant das kardiovaskuläre Risiko, indem es die pro-inflammatorischen und pro-atherosklerotischen Kaskaden vermindert. / 6 month old obese Zucker rats were fed with cannabinoid receptor-1 antagonist rimonabant for 10 weeks. We demonstrate positive modulation of circulating monocyte numbers, reduced platelet activation and lower RANTES and MCP-1 levels by Rimonbant in Zucker rats. This may potentially contribute to a reduction of cardiovascular risk.
68

Pharmacological characterization of chemokine receptor 7 (CCR7) as a potential therapeutic target in cancer

Basheer, Haneen Adel Daoud January 2017 (has links)
The expression of CCR7 was evaluated in different cancer cell lines by using flow cytometry, western blot, Immunofluorescence and immunohistochemistry. We showed for the selected cell lines that the expression is maintained in cells grown as spheroids, and xenoplanted in mice. Furthermore, we showed the expression of CCR7 correlates with stage of the disease in patient derived head and neck cancer tissue. We also showed that expression of CCR7 in cancer cell lines correlates with migratory aptitude towards CCL21 in a scratch assay, Boyden chamber assay and spheroid invasion assay. We then showed that the expression of CCR7 is elevated under serum starvation and under hypoxia in cancer cell lines grown as monolayers and as spheroids; and that there is a correlation between hypoxia and CCR7 expression in spheroids, xenografted cells and clinical cancer tissue. However, we found that in cell line OSC-19, the increase in the expression of CCR7 did not correlate to increased migration. Our investigations following this observation showed that whilst hypoxia increases the expression of CCR7, it concurrently causes a decrease in reactive oxygen species (ROS) which strongly abrogates migratory aptitude in OSC-19, resulting in an overall loss of migration in OSC-19 cells. In addition, we characterised OSC-19 as a suitable model to evaluate small molecule CCR7 antagonists using a number of different assays. In particular, we showed that ICT13069 antagonised response of this cell line across a number of drivers of malignancy such as migration, invasion in 2D and 3D models.
69

The pmrHFIJKLM Operon in Yersinia pseudotuberculosis Enhances Resistance to CCL28 and Promotes Phagocytic Engulfment by Neutrophils

Johnson, Lauren Elizabeth 01 June 2016 (has links)
Yersinia pseudotuberculosis is a foodborne pathogen that is the ancestral strain to Yersinia pestis, the causative agent of Plague. Y. pseudotuberculosis invades a host through the intestinal epithelium. The bacteria resist mucosal innate immune defenses including antimicrobial chemokines and phagocytic cells, and replicate in local lymph nodes. They cause Tuberculosis-like symptoms, including necrosis of local tissue and granuloma formation. Like all bacteria, Y. pseudotuberculosis has a net negative charge, which contributes to its susceptibility to some cationic antimicrobial peptides. Y. pseudotuberculosis is able to reduce this negative charge by adding 4-amino-4-deoxy-L-arabinose (L-Ara4N) to the lipid A portion of lipopolysaccharide. The production and addition of the L-Ara4N is coded for by the pmrHFIJKLM (pmrF) operon. A previous study has shown that the Y. pseudotuberculosis pmrF operon is important for resistance against polymyxin, but is not important for virulence in mice. Several previous reports have shown a strong influence of growth temperature on resistance to antimicrobial peptides and pmrF expression in pathogenic Yersinia species, but these studies also suggest significant variability between species, and even between strains of individual species. In particular, the regulation of the Y. pseudotuberculosis pmrF operon and its effect on bacterial interactions with mucosa-associated antimicrobial chemokines and neutrophils is not understood. In these studies, we investigated the environmental influences on pmrF expression in Y. pseudotuberculosis. We found that the promoter activity of the pmrHFIJKLM operon is increased at lower temperatures (21ºC) and in the presence of human serum. A ΔpmrI mutant strain of Y. pseudotuberculosis defective for addition of L-Ara4N was found to be more susceptible to killing by the antimicrobial chemokine CCL28 compared to wild-type. This suggests that this gene is important in the bacterial defense against antimicrobial chemokines. However, when the ΔpmrI mutant strain was exposed to human neutrophils, there was a decrease in phagocytosis as compared to wild-type bacteria. Our results suggest that the regulation of L-Ara4N modifications in Yersinia is more complex than previously appreciated and varies between species. Addition of L-Ara4N to Y. pseudotuberculosis appears to enhance resistance to some antimicrobial peptides like CCL28 and promote greater phagocytic engulfment by neutrophils. These opposing effects may partly explain why there is no net apparent survival defect in mutants lacking the pmrF operon during infection.
70

Analysis of polymorphism in human cytomegalovirus (HCMV) chemokine, vCXCL-1, and its role in cellular activation

Heo, Jinho 01 December 2010 (has links)
The human cytomegalovirus (HCMV) viral chemokine gene, UL146, shows a high degree of variability in clinical isolates. The UL146-produced viral chemokine, vCXCL-1, has homology to CXC chemokines and is predicted to be an immune modulator that may contribute to the pathogenesis of HCMV infections. In the analysis of clinical isolates from congenitally infected infants, we found 11 distinct vCXCL-1 clades. Although the four cysteine residues that create two disulfide bonds providing the essential structure for CXC chemokines,are conserved, the N-loop region, which is important for receptor binding and activation, was hypervariable. One clade also contained a modified glutamic acid-leucine-arginine (ELR) motif (asparagine-glycine-arginine / NGR), which regulates binding to CXCR1 and CXCR2 receptors. Based on this sequence information, we hypothesize that these proteins differentially activate neutrophils, which may have a role in HCMV pathogenesis. To address these functional differences, we produced representative vCXCL-1 proteins from each of the 11 clades using a baculovirus protein expression system. Using competition binding assays, we have examined their binding affinities to either CXCR1 or CXCR2 expressed on HEK293 cells. All vCXCL-1s bound to CXCR2 with different binding affinities. Interestingly, only three vCXCL-1s bound to CXCR1 while the others demonstrated did not. We analyzed functional differences between the vCXCL-1s in calcium mobilization, adhesion molecule induction, and chemotaxis on human peripheral blood neutrophils (PBNs). Although the binding affinities to CXCR2 and/or CXCR1 were variable, all vCXCL-1s were capable of inducing intracellular calcium mobilization in PBNs and upregulating adhesion molecules on the surface of PBNs to similar levels as human CXCL1. However, the potency of the vCXCL-1s in the chemotaxis of neutrophils varied and was affinity independent. We also examined secondary chemokine production upon vCXCL-1 treatment on neutrophil-like HL60 T2 cells using real-time PCR. The results showed CCL22 induction was affinity dependent. Taken together, these results provide insights into the potential role of vCXCL-1 in HCMV pathogenesis and how the variability in these chemokines can affect neutrophil function.

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