Interleukins, cytokines secreted by leukocytes, are predominant messengers modulating immune responses. Interleukin-27 (IL-27), a key immunomodulatory cytokine, functions to induce both pro- and anti-inflammatory effects in various immune cells. IL-27 is a heterodimeric cytokine, composed of IL-27p28 and Epstein-Bar virus induced gene 3 (EBI3) subunits, and binds to a receptor composed of IL-27Rα (WSX-1) and gp130. Initial studies focused on describing IL-27 functions in skewing T helper cell development to a Th1 response, with few reports on functions in monocytes. Thus, in this thesis, I aimed to characterize novel functions of IL-27 in innate immune responses of monocytes. I initially established that IL-27 induced a pro-inflammatory cytokine profile (IL-6, IP-10, MIP-1α, MIP-1β, and TNF-α) mediated via STAT1/3 and NF-κB signaling pathways. Further investigation led to the discovery that IL-27 could enhance LPS responses via upregulation of TLR4 expression and NF-κB signaling. Together, these studies described novel signaling mechanisms (NF-κB and JAK/STAT crosstalk) and gene targets (cytokines and TLR4) of IL-27 that drive inflammatory responses. In continuing the quest for novel IL-27 functions in innate immunity, I reported IL-27 can upregulate expression of the IFN-responsive, antiviral protein called BST-2. My results showing IL-27-induced expression of BST-2 mRNA and cell surface protein were supported by previous studies reporting IL-27-induced expression of other antiviral molecules. Furthermore, previous studies showed IL-27 could inhibit HIV replication via antiviral gene induction, pointing to potential for IL-27 immunotherapies. In light of the posited role for IL-27 in therapeutics, it became inherently critical to describe how IL-27 functions in the setting of HIV infection. Thus, in my final thesis chapters, I described the effect of HIV infection on IL-27 expression and functions, addressing a substantial void in literature. Interestingly, a trend of decreased IL-27 expression and significant impairment of IL-27-induced gene expression was observed in HIV infection. Therefore, decreased circulating IL-27 and decreased IL-27 responsiveness may collectively dysregulate IL-27 function in HIV. This thesis describes novel, IL-27-driven, proinflammatory responses, and highlights impairment of IL-27 function in HIV infection. This work bridged a gap in knowledge of IL-27 functions in monocytes and highlighted multifaceted mechanisms underlying immunoregulation by IL-27. / Thesis (Ph.D, Microbiology & Immunology) -- Queen's University, 2012-04-12 13:07:50.588

Les prostaglandines sont de petites molécules qui jouent d'importants rôles immunomodulateurs au niveau du système immunitaire. Elles contribuent notamment à l'établissement de l'inflammation et à la résolution de celle-ci. La prostaglandine J 2 (15d-PGJ2 ) est d'ailleurs l'une des prostaglandines les plus étudiées en vertu de ses activités anti-inflammatoires. En effet, il a été démontré que celle-ci peut inhiber plusieurs molécules dont plusieurs cytokines et le facteur de transcription NF-?B. D'un autre côté, l'effet de la 15d-PGJ 2 sur l'interleukine-13 (IL-13) est encore inconnu à ce jour. L'IL-13 est une cytokine produite principalement par les cellules T et qui module plusieurs types de cellules immunitaires, tant au niveau de leur différentiation que de leur activation. De plus, cette cytokine contribue à l'établissement de certaines pathologies telles que l'asthme et la colite ulcéreuse lorsqu'elle est surexprimée. L'objectif principal de ce mémoire est de vérifier l'effet de la 15d-PGJ 2 sur l'expression et la production de l'IL-13 par les cellules T. Les résultats obtenus dans ce projet démontrent que la I 5d-PGJ2 inhibe la production de l'IL-13 par les cellules T. En effet, autant la lignée cellulaire de lymphocytes T CD4+ Jurkat E6.1 que les cellules mononucléaires circulant dans le sang (de l'anglais PBMCs ) stimulés par des agents mimant l'activation des cellules T tels que le PMA et la ionomycine, puis traités à la 15d-PGJ 2 ont montré une inhibition dans l'expression et la production de l'IL-13. Les résultats ont également révélé un effet similaire lorsque les cellules étaient pré-traitées à I 5d-PGJ2 , puis stimulées avec PMA/ionomycine. Par ailleurs, plusieurs éléments sont essentiels pour activer la transcription de l'IL-13, dont le facteur de transcription NF-?B. D'un autre côté, il est connu que la 15d-PGJ2 inhibe la cascade de signalisation de NF-?B. Ainsi, nous avons voulu vérifier si NF-?B était impliqué dans le mécanisme d'inhibition de l'IL-13 par la 15d-PGJ2 . Pour ce faire, des extraits nucléaires ont été réalisés avec les Jurkat E6.1 et les PBMCs traitées à la 15dPGJ2 puis un essai de retard sur gel (de l'anglais EMSA, Electromobility shift assay ) a été fait avec une sonde NF-?B consensus ou une sonde d'un site de liaison putatif de NF-?B dans le promoteur IL-13. Les résultats ont révélé que le facteur de transcription NF-?B était effectivement activé lors de la transcription de l'IL-13 et inhibé lors d'un traitement à la 15d-PGJ 2 . Par la suite, puisqu'il a déjà été démontré que la 15d-PGJ2 active le récepteur nucléaire PPAR-?, nous avons voulu vérifier si le mécanisme d'inhibition de l'IL-13 dépendait ou non de ce dernier. Un antagoniste irréversible de PPAR-? a donc été utilisé dans les expériences, et l'essai a permis d'établir que le mécanisme d'inhibition de l'IL-13 parla 15d-PGJ 2 était indépendant de PPAR-?. Finalement, ces résultats dévoilent que la 15d-PGJ 2 inhibe l'expression et la production de l'IL-13, que cet effet serait indépendant de PPAR-?, et qu'il impliquerait probablement une inhibition du facteur de transcription NF-xB. Ces résultats pourraient avoir des implications cliniques où l'IL-13 joue un rôle d'importance, tels que l'asthme et la colite ulcéreuse. L'utilisation de cette prostaglandine en combinaison avec les traitements habituels, par exemple les corticostéroïdes, pourrait être envisagée.

T-ALL accounts for 15% of childhood leukemias and approximately 60% of patients overexpress TAL1. TAL1/SCL encodes a transcription factor that regulates hematopoiesis by dimerizing with additional transcription factors including E12, E47, and GATA-1. TAL1 has also been found to repress expression of NF-κB1, potentially promoting formation of an NF-κB p65/c-Rel heterodimer that encourages cell survival by up-regulating IAPs and IκB. However, the correlation between TAL1 and p65/c-Rel expression and their effects on downstream targets like IKK, IκB, and other anti-apoptotic proteins is poorly understood. Jurkat cells, expressing TAL1, were treated with TNFα and/or etoposide to induce apoptosis and experiments were performed to assess the expression of proteins of interest. Caspase-8 activity assays were also performed to help delineate the apoptotic signal present in these cells. Determining if interactions between TAL1, NF-κB, and other downstream targets help promote apoptotic resistance will further research into better, more targeted treatments for T-ALL. / Department of Biology

B virus (Cercopithecine herpesvirus 1) is an alphaherpesvirus indigenous to macaque monkeys and is closely related to herpes simplex virus type 1 (HSV-1). Disease caused by B virus, which is often mild or asymptomatic in its natural host, the macaque monkey, is similar in infected macaques to HSV-1 infection in humans. When B virus zoonotically infects foreign hosts, e.g., humans, high morbidity and mortality are evidenced in > 80% of untreated cases. To explore the underlying reasons for differences in pathogenesis between B virus and HSV-1 infection in humans, human microarrays were used to comparatively examine global cellular gene expression patterns engaged as a result of infection of human foreskin fibroblasts (HFFs). Our results demonstrate that these closely related simplexvirus family members have divergent strategies to thwart host cell pathways related to innate defenses. In these studies, B virus did not induce detectable interferon, cytokine or chemokine genes, in sharp contrast to HSV-1, which induced innate immune responsive genes in infected cells. Although no innate immune response genes were found to be up-regulated by B virus infection, B virus induced I£eB£a, which was the only gene found to be involved in the NF-£eB signaling pathway within the innate immunity biological network. Quantification of NF-£eB p50 DNA binding activity in virus-infected nuclear extracts demonstrated that NF-£eB p50 DNA binding activity was lower in B virus-infected cells. Suppression of I£eB£a in B virus infected cells by siRNA restored NF-£eB-induced cytokine and chemokine expressions. Data presented here support the model that I£eB£a inhibits NF-£eB regulated immune responsive genes in B virus-infected HFF cells, and this response differs from that observed in HFF cells infected with HSV-1. The result is that B virus alters the NF-£eB regulated expression of cytokine and chemokine genes of HFF cells differently from HSV-1 early after infection. These differences in cytokine and chemokine expression may be associated with the delayed or reduced host responses observed in B virus infected humans and underlie the failure of adaptive responses in zoonotically infected humans.

Dissertation (Ph.D.)--University of Toledo, 2007. / "In partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biomedical Sciences." Title from title page of PDF document. Bibliography: p. 72-96.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 136-148).

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 106-118).

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 134-155).

Thesis (Ph.D. in Immunology) -- University of Colorado at Denver and Health Sciences Center, 2006. / Typescript. Includes bibliographical references (leaves 129-141). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2002. / Härtill 4 uppsatser.