1,720,980 research outputs found
Protromic and functional study of Acinetobacter abumannii outer membrane vesicles
Full text linkThe author has granted permission for their work to be available to the general public.<italic>Acinetobacter baumannii<italic>, a gram-negative aerobic bacterium, is one of the most spread bacteria which can be easily isolated from water, soil, and hospital facilities. It may cause various types of diseases such as respiratory tract infection, urinary tract infection, nosocomial pneumonia and bacteremia. It was noticed that <italic>A. baumanii<italic> was existed in the blood stream of military people deployed in Iraq and Afghanistan who suffered with serious injury. The treatment for the infection of <italic>A. baumannii<italic> is limited because it resists to resist nearly 90% of antibiotics. Therefore, to better treat the infection of <italic>A. baumannii<italic>,the mechanism of infection and virulence factors involved in pathogenecity needed to be studied. Similar to other gram-negative bacteria, outer membrane vesicles (OMVs) secreted by A. baumannii consisted of virulence factors. In my study, the <italic>A. baumannii<italic> OMVs were isolated and observed under transmission electron microscopy. The proteomic analysis indicated that <italic>A. baumannii<italic> OMVs consisted of various virulence factors such as OmpA. To understand the function of the <italic>A. baumannii<italic> OMVs, OMVs were incubated with macrophage cells. Results showed the macrophage cells were lysed when incubated with OMVs compared to cells in the control group which were intact. The quantification of cytotoxicity caused by OMVs showed that the mortality rate reached 80% when 0.02 ug/ml OMVs were added.
In my study, the OMVs were isolated and observed. The virulence factors were identified by proteomic analysis and OMVs are toxic to macrophage cells in vitro.Integrative Biolog
Generation and Screening a Library of Coxiella burnetii Nine Mile Phase II Mutants
No full textThis item is available only to currently enrolled UTSA students, faculty or staff. To download, navigate to Log In in the top right-hand corner of this screen, then select Log in with my UTSA ID.Coxiella burnetii is a highly infectious human pathogen that causes a global zoonotic disease called Q fever. Although the organism was first isolated more than 80 years ago, its virulence mechanisms are poorly understood which is mostly due to its intracellular lifestyle. Recent advances such as the development of axenic culture which allows the growth of this bacterium, that was once believed to be an obligate intracellular pathogen, outside of a host-cell, and new genetic manipulation tools has helped scientists make significant progress in studying this microorganism and identification and characterization of its pathogenesis mechanisms. In the work described in this thesis, we generated a library of C. burnetii Nine Mile phase II (NMII) RSA 439 (that is approved for use in a biosafety level two laboratory) transposon insertion mutants and conducted a visual screen to identify genes required for intracellular replication of this bacterium with the help of indirect immunofluorescence assays. Three mutants with severe intracellular growth defects were found although they showed a normal growth in the bacteriological medium. These three mutants had insertions in genes responsible for encoding D-alanyl-D-alanine carboxypeptidase/D-alanyl-D alanine-endopeptidase, ABC transporter ATP-binding protein and LysM peptidoglycan-binding domain-containing protein. To verify our findings, genomic equivalents of NMII mutants were assessed by real-time PCR which showed a significant reduction in their growth. Since quantitative PCR detects the presence of bacterial DNA but does not indicate viability of the bacteria, colony formation assays were conducted and once again verified our findings and showed a decrease in the intracellular growth rate of these mutants.Integrative Biolog
IgA deficiency potentiates altered respiratory function following neonatal pulmonary chlamydial infection
No full textThis item is available only to currently enrolled UTSA students, faculty or staff. To download, navigate to Log In in the top right-hand corner of this screen, then select Log in with my UTSA ID.Neonatal Chlamydia lung infections are associated with serious sequelae such as asthma and airway hyperreactivity (AHR) in children and adults. However, the role of B-cells and the major mucosal antibody IgA in pathogenesis have not been modeled. Objectives: We hypothesize that B-cells and antibodies play a protective role against development of later life serious respiratory sequelae to Chlamydia infection of newborns. One day old pups of wild type (WT), B-cell-/- (μMT) and IgA-/- C57BL/6 mice were challenged intranasally (i.n.) with 100 IFUs of C. muridarum and monitored 30 days for morbidity and mortality. Chlamydial burdens in lungs, liver and spleen were assessed on days 4, 7, 10, 14 and 18 post-challenge (PC). Anti- Chlamydia serum IgG titers were determined on days 15 and 30 PC. Lung functions were analyzed at 5 weeks PC using the FlexiVent system. All B-cell-/- animals succumbed to the pulmonary chlamydial infection by 30 days PC while all WT and IgA-/- animals survived. Additionally, comparable Chlamydia burdens and dissemination profiles observed between WT and IgA-/- animals was coincident with comparable total antigen-specific IgG, suggesting that while B cells were essential in protection against pulmonary neonatal Chlamydia infection, IgA was dispensable. However, comparative respiratory functional analysis revealed a significant shift upward in P-V loops and higher dynamic resistance in IgA-/- animals, suggesting that IgA might play a protective role in alleviating respiratory pathological sequelae. B-cells protect against chlamydial neonatal infection and IgA plays a protective role against later life serious respiratory sequelae; the basis of this protection is being investigated.Integrative Biolog
Expression of IL-5 and IL-13 by Th2 cells in experimental autoimmune encephalomyelitis
No full textThe author has granted permission for their work to be available to the general public.Multiple Sclerosis is considered an autoimmune disease where CD4 + T cells play an important role in promoting pathology. It affects approximately 2.5 million people in the world with approximately 400,000 of them in the US. There is no cure for the disease but treatments are available to manage symptoms and to prevent the progression of the disease. Although the exact cause of MS is unknown, it is believed that an imbalance between Th1 and Th2 cytokines within the CNS may promote or induce the disease. CD4 + T cells have been classified into different lineages such as Th1, Th2 and Th17 cells. Activated Th1 and Th17 cells produce proinflammatory cytokines such as IFN-gamma and IL-17 and are thought to promote autoimmune disease pathology. In contrast, Th2 cells produce cytokines such as IL-4, IL-5, IL-10 and IL-13 that are thought to regulate pathogenic effecter Th1 and Th17 cells. It has been suggested that Th2 cells producing IL-5 and/or IL-4 cannot inhibit pathogenic T cells directly in the CNS but may act in the periphery. However, it has not been addressed whether Th2 cells produce immunoregulatory IL-13 in the CNS at the site of autoimmune inflammation. Importantly, it has remained unresolved when or even if IL-13 and IL-5 are co-expressed.
Our results show production of IL-5 by Th2 cells in the CNS during EAE, but not IL-13. In contrast, IL-5 and IL-13 are produced by Th2 cells in the spleen. Our results suggest that IL-13 and IL-5 are being co-produced by CD4+T cell populations. Interestingly, it seems that there were no populations only expressing IL-13, but there were IL-5 single staining cells. This might suggest that some cells produce both cytokines and some only produce IL-5, or that at some later point the IL-5 and IL-13 double producing cells may produce less IL-13.
Overall, our results suggest that Th2 cells do not produce IL-13 in the CNS, which could explain why Th2 cells fail to inhibit autoimmune inflammation during EAE.Integrative Biolog
Exploring the Impact of TNFR2 on Regulatory T Cells and Astrocytes in Experimental Autoimmune Encephalomyelitis (EAE)
No full textThis item is available only to currently enrolled UTSA students, faculty or staff. To download, navigate to Log In in the top right-hand corner of this screen, then select Log in with my UTSA ID.The full text of this item is not available at this time because the author has placed this item under an embargo until May 25, 2025.Multiple Sclerosis (MS) is a chronic autoimmune disease of the central nervous system which affects over 2 million people worldwide. MS is a heterogenous disease characterized by recurrent, remitting and/or progressive neurological deficits, and clinical manifestations include nerve damage, visual loss, motor and balance impairment, gait disturbance, pain, and others. While several environmental and genetic risk factors have been identified, such as having the human leukocyte antigen DR2b (DRB1*15:01) haplotype, the molecular mechanisms underlying the development and severity of MS remain poorly understood. Tumor necrosis factor (TNF) is a cytokine that exerts its effects through two different surface receptors TNFR1 and TNFR2, and it has been identified as a key player in MS pathogenesis. TNFR2 is thought to have a protective role in experimental autoimmune encephalomyelitis (EAE), a mouse model for MS. However, TNFR2 role in health and disease remains controversial and incompletely understood. Previous data from our lab demonstrated that in the absence of TNFR2, transgenic mice expressing the DR2b allele develop a more severe and progressive form of EAE, exhibiting astrogliosis. Using our transgenic TNFR2 knock out model, we were able to explore TNFR2 influence on gene expression in CD4+ T cells and astrocytes, and to functionally and phenotypically characterize TNFR2 deficient Tregs. Additionally, we were able to optimize a way to identify gene and protein expression within mice brain to further determine the presence and characteristics of reactive astrocytes in our mice models during EAE. Our results provide key insights into the mechanism by which TNFR2 regulates Treg and astrocyte function in the context of EAE.Molecular Microbiology and Immunolog
The study of the role of TNF-alpha following primary and secondary infection with genital Chlamydia muridarum
No full textThis item is available only to currently enrolled UTSA students, faculty or staff. To download, navigate to Log In in the top right-hand corner of this screen, then select Log in with my UTSA ID.The role of tumor necrosis factor (TNF-&agr;) in host defense against chlamydial infection remains unclear. Some studies have suggested that TNF-&agr; may be important based on the observation of delayed resolution of chlamydial infection in TNF-&agr;R deficient mice. However, in contradiction is a report showing minimal difference in vaginal Chlamydia clearance between wild type and antibody depleted TNF-&agr; deficient mice. The goal of the present study was to evaluate the mechanistic role of TNF-&agr; in host defense following primary and secondary infection with Chlamydia muridarum in wild type and TNF-&agr; deficient mice. We observed that TNF-&agr; deficient mice show comparable levels of antibody and chlamydial clearance after both primary and secondary infection to wild type animals. From the cell mediated and humoral responses analyses, it was determined that TNF-&agr; and IFN-gamma acted independent of each other, and there is no synergistic mechanisms of action in protective immunity. Collectively, this study suggests that TNF-&agr; may not play a significant role in the clearance of genital chlamydial infection.Integrative Biolog
Construction and analysis of novel strains to examine the genetic regulation of Candida albicans filamentation
No full textThis item is available only to currently enrolled UTSA students, faculty or staff. To download, navigate to Log In in the top right-hand corner of this screen, then select Log in with my UTSA ID.Candida albicans is a fungus that lives as a commensal organism on many muscosal surfaces of the human body but can also behave as a pathogen causing both treatable illnesses as well as a more serious disease known as disseminated candidiasis. C. albicans exists in three distinct morphotypes: yeast, pseudohyphae, and hyphae. It has been accepted that the ability of the fungus to switch between the yeast and filamentous types is the main source of its virulence. This transition is governed by a network of signaling pathways involving many transcriptional regulators of hyphal growth one of which being the repressor Nrg1p. Recently, we demonstrated that Brg1p, a positive regulator of filamentation is involved in a feedback mechanism with NRG1, whereby BRG1 overexpression induces hypha formation through the production of an antisense RNA molecule and subsequent destabilization of NRG1 mRNA. Since this is the first known example of antisense RNA production in C. albicans, we sought to determine if the stated transcript destabilization was occurring through the mechanism of RNAi by constructing deletion mutants of Dicer and Argonaute (the main proteins involved in RNAi) and examining their ability to form hyphae. We also sought to investigate the functions of other genes that are down-regulated by NRG1 (like BRG1) as they too could shed light on the yeast to hypha transition. We chose three transcription factors SEF2, ZCF3, and ZCF35 to construct overexpression strains with and test their ability to induce filamentation alone and in the context of Nrg1p-mediated repression.Integrative Biolog
Investigating aire deficiency in the context of human autoimmune disease associated HLA molecules
No full textThis item is available only to currently enrolled UTSA students, faculty or staff. To download, navigate to Log In in the top right-hand corner of this screen, then select Log in with my UTSA ID.Autoimmunity arises as a result of the immune system initiating an attack on self-molecules. Autoreactive T cells are one of the key mediators in many autoimmune diseases such as multiple sclerosis (MS) and rheumatoid arthritis (RA). Central tolerance induced in the thymus is the key mechanism involved in eliminating these autoreactive T cells that recognize self antigens. The autoimmune regulator (AIRE) gene regulates central tolerance by mediating ectopic transcription of self antigens in the thymus. Deficiency of AIRE in humans can break the central tolerance causing a multi-organ autoimmune disorder known as autoimmune polyendocrinopathy syndrome (APS I). Aire deficient mice <italic>(aire-/-)<italic> can develop spontaneous autoimmune disease characterized by multi-organ specific lymphocytic infiltrates. The association between HLA-DR2 and DR4 molecules to MS and also RA has been established. The aim of the study was to investigate aire deficiency in mice in the context of the human autoimmune disease associated MHC alleles; HLA-DR2 and HLA-DR4. The detection of T cell infiltrates in liver and pancreas and autoantibody production against the gastric tissue in a few older <italic>aire-/-<italic> DR2 and DR4 transgenic mice suggested that these mice develop mild spontaneous autoimmunity. Further we also observed that mild autoimmunity could be triggered in the <italic>aire-/-<italic> transgenic DR2 and DR4 mice by abrogation of T regulatory cell function through the use of blocking antibody against CTLA-4 and CD25. We also observed that aire deficiency appeared to have a mild effect on promoting experimental autoimmune encephalomyelitis (EAE), particularly in the DR2 transgenic background. Also, Treg inactivation after EAE induction in
<italic>aire-/-<italic> DR2 transgenic mice showed a mild disease enhancing effect in female mice. Thus, the study revealed that aire deficiency in the context of HLA-DR2 and DR4 molecules elicited a mild spontaneous autoimmune phenotype.Integrative Biolog
Comparison of enzymatically active and denatured recombinant chlamydial protease like activity factor as protective immunogens against genital chlamydial challenge
No full textThis item is available only to currently enrolled UTSA students, faculty or staff. To download, navigate to Log In in the top right-hand corner of this screen, then select Log in with my UTSA ID.We have shown previously the efficacy of intranasal vaccination with recombinant chlamydial protease-like activity factor (rCPAF) plus interleukin-12 in the induction of enhanced genital chlamydial clearance and reduction of upper genital tract pathology. The protective immunity was mediated by IFN-gamma producing CD4+ T cells, and did not require antibody, suggesting the predominant contribution of linear antigenic epitopes in this process. Moreover, CPAF is a protease that can degrade several host proteins, and may not be suitable for administration into humans in the proteolytically active form. Therefore, in this study, we compared the protective efficacy of proteolytically active and inactive (heat-denatured) rCPAF against primary genital C. muridarum challenge. Purified rCPAF was able to degrade human keratin 8 in a cell-free degradation assay before, but not after, heating at 95°C for 5 min, suggesting the generation of proteolytically active and inactive rCPAF. Active, but not inactive, rCPAF immunization induced high levels of anti-active CPAF total antibody, IgG1, IgG2a, and IgG2b. Both active and inactive rCPAF immunization induced robust splenic IFN-gamma production upon stimulation with rCPAF or native CPAF produced during an active chlamydial infection of HeLa cells. Vaccination with active and inactive rCPAF induced enhanced vaginal chlamydial clearance as early as day 6 after challenge, and every time-point thereafter, compared to mock-vaccinated animals. Moreover, active and inactive rCPAF vaccinated animals completely cleared the infection by day 18, compared to mock-vaccinated mice that cleared by day 30 after challenge. Importantly, only 33% of active and inactive rCPAF-vaccinated mice displayed hydrosalpinx compared to 83% of mock-vaccinated animals. The degree of microscopic oviduct pathology also was significantly reduced in active and inactive rCPAF-vaccinated mice compared to mock-vaccinated animals. Collectively, these results demonstrate that rCPAF conformation is not a constraint for induction of robust protective anti-chlamydial immunity, and further suggest that rCPAF is a safe, effective, and stable anti-chlamydial vaccine candidate.Integrative Biolog
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