[Show abstract][Hide abstract] ABSTRACT: Despite a flourishing biomedical and global health industry too few of Washington state's precollege students are aware of this growing sector and emerging ideas on bacteria, fungi, parasites and viruses. Against the backdrop of numerous reports regarding declining precollege student interest in science, a precollege program was envisioned at Seattle Biomedical Research Institute (as of 2010, Seattle BioMed) to increase youth engagement in biomedical research and global health, increase community interest in infectious diseases and mobilize a future biomedical workforce. Since 2005, 169 rising high school juniors have participated in the BioQuest Academy precollege immersion program at Seattle BioMed. Assembling in groups of 12, students conduct laboratory experiments (e.g., anopheline mosquito dissection, gene expression informed tuberculosis drug design and optimizing HIV immunization strategies) related to global health alongside practicing scientific mentors, all within the footprint the institute. Laudable short-term impacts of the program include positive influences on student interest in global health (as seen in the students' subsequent school projects and their participation in Seattle BioMed community events), biomedical careers and graduate school (e.g., 16.9% of teens departing 2008-2009 Academy report revised goals of attaining a doctorate rather than a baccalaureate diploma). Long-term, 97% of alumni (2005-2008) are attending postsecondary schools throughout North America; eight graduates have already published scientific articles in peer-reviewed journals and/or presented their scientific data at national and international meetings, and 26 have been retained by Seattle BioMed researchers as compensated technicians and interns. Providing precollege students with structured access to practicing scientists and authentic research environments within the context of advancing global health has been a robust means of both building a future pool of talented leaders and engaged citizenry and increasing the visibility of health disparities within the community.
PLoS ONE 01/2010; 5(11):e13814. · 3.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The intracellular bacterial pathogen Chlamydia is sequestered from the host cell cytoplasm by remaining within an inclusion body during its replication cycle. Nevertheless, CD8(+) T cells recognizing Chlamydia Ags in the context of MHC class I molecules are primed during infection. We have recently described derivation of Chlamydia-specific human CD8(+) T cells by using infected dendritic cells as a surrogate system to reflect Chlamydia-specific CD8(+) T cell responses in vivo. These CD8(+) T cell clones recognize chlamydial Ags processed via the conventional class Ia processing pathway, as assessed by treatment of infected APC with lactacystin and brefeldin A, suggesting that the Ags are translocated from the chlamydial inclusion into the host cell cytosol. In this study, outer membrane protein 2 (OmcB) was identified as the Ag recognized by one of these Chlamydia-specific human CD8(+) T cells, and we defined the HLA*A0101-restricted epitope from this Ag. CD8(+) T cell responses to this epitope were present at high frequencies in the peripheral blood of both of two HLA*A0101 donors tested. In vitro chlamydial growth was completely inhibited by the OmcB-specific CD8(+) T cell clone independently of lytic mechanisms. OmcB is a 60-kDa protein that has been postulated to be associated with the Chlamydia outer membrane complex. The subcellular localization of OmcB to the cytosol of infected cells, as determined by conventional MHC class I Ag processing and presentation, suggests the possibility of an additional, cytosolic-associated function for this protein.
The Journal of Immunology 01/2005; 173(11):6905-13. · 5.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Chlamydia trachomatis is an obligate intracellular gram-negative bacterium responsible for a wide spectrum of diseases in humans. Both genital and ocular C. trachomatis infections are associated with tissue inflammation and pathology. Dendritic cells (DC) play an important role in both innate and adaptive immune responses to microbial pathogens and are a source of inflammatory cytokines. To determine the potential contribution of DC to the inflammatory process, human DC were infected with C. trachomatis serovar E or L2. Both C. trachomatis serovars were found to infect and replicate in DC. Upon infection, DC up-regulated the expression of costimulatory (B7-1) and cell adhesion (ICAM-1) molecules. Furthermore, chlamydial infection induced the secretion of interleukin-1beta (IL-1beta), IL-6, IL-8, IL-12p70, IL-18, and tumor necrosis factor alpha (TNF-alpha). The mechanisms involved in Chlamydia-induced IL-1beta and IL-18 secretion differed from those of the other cytokines. Chlamydia-induced IL-1beta and IL-18 secretion required infection with viable bacteria and was associated with the Chlamydia-induced activation of caspase-1 in infected host cells. In contrast, TNF-alpha and IL-6 secretion did not require that the Chlamydia be viable, suggesting that there are at least two mechanisms involved in the Chlamydia-induced cytokine secretion in DC. Interestingly, an antibody to Toll-like receptor 4 inhibited Chlamydia-induced IL-1beta, IL-6, and TNF-alpha secretion. The data herein demonstrate that DC can be infected by human C. trachomatis serovars and that chlamydial components regulate the secretion of various cytokines in DC. Collectively, these data suggest that DC play a role in the inflammatory processes caused by chlamydial infections.
Infection and Immunity 01/2005; 72(12):7231-9. · 4.07 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: CD8(+) T cells are a key immune component for the eradication of many intracellular pathogens. This study aims to characterize the human CD8(+) T cell response to naturally processed chlamydial Ags in individuals exposed to the intracellular pathogen Chlamydia trachomatis. By using C. trachomatis-infected autologous dendritic cells (DCs) as stimulators, Chlamydia-reactive CD8(+) T cell responses were detected in all 10 individuals tested. The majority of the Chlamydia-reactive CD8(+) T cells were non-MHC class Ia restricted in all three of the individuals tested. From one donor, three non-class Ia-restricted and two class Ia-restricted Chlamydia-specific CD8(+) T cells were cloned and characterized further. All five T cell clones secreted IFN-gamma in response to autologous DCs infected with viable Chlamydia, but not with DCs pulsed with inactivated chlamydial elementary bodies. MHC class Ia-restricted and non-class Ia-restricted responses were inhibited by DC treatment with a proteasomal inhibitor and an endoplasmic reticulum-Golgi transport inhibitor, suggesting that these T cells recognize a peptide Ag translocated to the host cell cytosol during infection that is processed via the classical class Ia Ag-processing pathway. Even though both restricted and nonrestricted CD8(+) T cells produced IFN-gamma in response to Chlamydia-infected fibroblasts, only the non-class Ia-restricted cells were lytic for these targets. The class Ia-restricted CTLs, however, were capable of cytolysis as measured by redirected killing. Collectively, these data demonstrate that both class Ia-restricted and non-classically restricted CD8(+) T cells are elicited in C. trachomatis-exposed individuals. Their role in host immunity remains to be elucidated.
The Journal of Immunology 11/2003; 171(8):4278-86. · 5.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: LeIF, a gene homologue of the eukaryotic initiation factor 4A was first described as a leishmanial antigen that induced a Th1-type T cell response in peripheral blood mononuclear cells (PBMC) from leishmaniasis patients. Moreover, the interferon (IFN)-gamma production by PBMC was found to be interleukin (IL)-12 dependent. Herein, we characterize the effects of LeIF on cytokine production and expression of surface molecules by normal human monocytes as well as by monocyte-derived macrophages and dendritic cells (MoDC). LeIF was a strong inducer of IL-12 and, to a lesser extent, of IL-10 and tumor necrosis factor (TNF)-alpha in macrophages and MoDC. IL-12 production did not require CD40 triggering, confirming that the ability of LeIF to induce IL-12 was not mediated through an effect on T cells. However, addition of soluble CD40 ligand (L) synergistically augmented IL-12 production in macrophages and MoDC. The cytokine-inducing activity of LeIF is located in the N-terminal portion of the molecule and was both proteinase K sensitive and polymyxin B resistant. LeIF, lipopolysaccharide and fixed Staphylococcus aureus all induced comparable amounts of IL-12, validating the potent cytokine-inducing effects of LeIF. Moreover, of these stimuli, LeIF had the highest IL-12/IL-10 and IL-12/TNF-alpha ratio demonstrating the preference of LeIF for IL-12 induction. Studies investigating the expression of surface molecules showed that LeIF up-regulated B7-1 and CD54 (ICAM-1) on macrophages and MoDC. To our knowledge this is the first report describing IL-12 production, up-regulation of co-stimulatory and intercellular adhesion molecules by monocytic antigen-presenting cells in response to a protein from a pathogenic microorganism. These immunomodulatory characteristics of LeIF might be excellent properties for a Th1-type adjuvant.
European Journal of Immunology 11/1997; 27(10):2634-42. · 4.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Thesis (Ph. D.)--University of Washington, 2004 Chlamydia trachomatis is an obligate intracellular Gram-negative bacterium responsible for a wide spectrum of diseases in humans. Both genital and ocular C. trachomatis infections are associated with tissue inflammation and pathology. To determine the potential contribution of dendritic cells (DC) to the inflammatory process, human DC were infected with C. trachomatis. C. trachomatis serovars E and L2 were both found to infect and replicate in DC. Upon infection, DC up-regulated the expression of co-stimulatory (B7-1) and cell adhesion (ICAM-1) molecules and induced the secretion of IL-1beta, IL-6, IL-8, IL-12p70, IL-18 and TNF-alpha. Chlamydia-induced IL-1beta and IL-18 secretion, unlike Chlamydia-induced secretion of the other cytokines, required both infection with viable bacteria and chlamydial protein synthesis and were correlated with the Chlamydia-induced activation of caspase-1 in infected host cells. Interestingly, an antibody to TLR4 inhibited Chlamydia -induced IL-1beta, IL-6 and TNF-alpha secretion. C. trachomatis -infected autologous DC were used to characterize the human CD8 + T cell response to naturally processed chlamydial antigens in individuals exposed to C. trachomatis. Chlamydia-reactive CD8 + T cell responses were detected in all 10 individuals tested and the majority of these were non-MHC class Ia-restricted in all 3 of the individuals tested. From one donor, three non-class Ia-restricted and two class Ia-restricted Chlamydia-specific CD8+ T cells were cloned and characterized further. All five T cell clones secreted interferon gamma (IFNgamma) in response to autologous DC infected with viable Chlamydia but not with DC pulsed with inactivated chlamydial elementary bodies. MHC class Ia-restricted and non-class Ia-restricted responses were inhibited by DC treatment with a proteasomal inhibitor and an ER-Golgi transport inhibitor, suggesting that these T cells recognize a peptide antigen translocated to the host cell cytosol during infection. Even though both restricted and non-restricted CD8+ T cells produced IFNgamma in response to Chlamydia -infected fibroblasts, only the non-class Ia-restricted were lytic for these targets. The class Ia restricted CTL were, however, capable of cytolysis as measured by re-directed killing. An expression cloning strategy was used to identify CT443 as the antigen recognized by one of these C. trachomatis specific human CD8+ T cells, and the HLA*A0101 restricted epitope from this antigen was defined.