Browsing by Subject "Mycoplasma"
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Item Dendritic Cell and Macrophage Activation and Maturation in Response to Mycoplasma(2003-08-01) Senne, Jordan Elliott; Jerry SimeckaSenne, Jordan. Dendritic Cell and Macrophage Activation and Maturation in Response to Mycoplasma. Master of Science (Microbiology and Immunology), July 2003. 47 pp., 7 illustrations. Murine respiratory mycoplasmosis, caused by Mycoplasma pulmonis, offers a model for studying the immunopathogenic mechanism of mycoplasma respiratory disease. My focus was to determine the effects of M. pulmonis on dendritic cells and macrophages. I demonstrated an increase in dendritic cell numbers and cell surface marker expression within the lungs of infected mice. However, there was no increase in the studied cytokine mRNA levels. In vitro studies determined increases in cytokine proteins and cytokine mRNA levels in dendritic cell and macrophages without a significant increase in cell surface marker expression by either cell line. Thus, a mycoplasma infection is able to stimulate dendritic cells both in vivo and in vitro, while macrophages are stimulated in vitro. Such findings could be helpful towards the development of future mechanisms for therapy against mycoplasma respiratory diseases.Item IL-17A ENHANCES DISEASE PATHOLOGY IN BALB/C MICE WHILE CONTRIBUTING TO HOST PROTECTION IN THE C57BL/6 STRAIN DURING INFECTION WITH MYCOPLASMA PULMONIS(2014-03) Mize, Maximillion T.; Simecka, JerryMycoplasma are bacterial organisms that can cause disease within the airways. Specifically, Mycoplasma pneumoniae causes pneumonia in humans which accounts for 30% of all cases of pneumonia worldwide with 100,000 cases per year resulting in hospitalization. This disease is characterized by a persistent infection, often leading to the initiation of chronic inflammation thus damaging the lungs and respiratory tract. In addition, it can also potentiate the disease severity of other respiratory conditions, such as asthma. Infection is often associated with close-quarter communities (i.e. dormitories, military barracks, etc.) allowing for quick spread of the disease. Furthermore, mycoplasma have also been found in livestock demonstrating that this bacteria has infiltrated important aspects of human society. Due to its resistance to antibiotics, such as penicillin, research has been forced to focus on alternative methods to treating disease. Interleukin-17A (IL-17A), a molecule secreted by immune cells, promotes inflammation and has also been implicated in the development of chronic inflammatory conditions. However, the role that IL-17A plays in chronic airway inflammation associated with Mycoplasma infection is currently unknown. Here, we use a mouse model of human pneumonia to determine if IL-17A contributes to tissue damage associated with disease. We demonstrate that targeting IL-17A with antibodies that block its biological function decreases disease severity within a susceptible BALB/c mouse strain. This alleviation was associated with decreased weight loss and lung damage when compared to identical mice not given antibody treatment. However, this method did not decrease bacterial numbers indicating that IL-17A is only associated with inflammation and not clearance of the organism. Interestingly, the opposite affect was seen in the more resistant C57BL/6 mouse strain leading our lab to believe that a genetic predisposition may be the underlying cause of IL-17A associated airway inflammation. A particular genetic background may dictate the amount of IL-17A released during infection, with high amounts predisposing an individual to severe and irreversible tissue damage, thus initiating a state of chronic inflammation. Purpose (a): Mycoplasma cause 30% of all cases of pneumonia worldwide. Infections induce chronic airway inflammation and has also been associated with the exacerbation of other respiratory diseases, like asthma. Due to a prevalence tied to close-quarter communities (dorms, military barracks, etc.), and the possession of a reservoir in livestock, it has infiltrated human society. Furthermore, the lack of a cell wall prevents this organism from being treated with beta-lactam antibiotics forcing research to focus on alternative treatment methods. While Interleukin-17A (IL-17A) has been linked to the induction of chronic inflammatory diseases, its role in mycoplasmosis is currently unknown. Here, we hypothesize that IL-17A leads to chronic inflammation, exacerbating disease pathogenesis. Methods (b): Female BALB/c and C57BL/6 mice, aged 6-12 weeks, were obtained from HARLAN Laboratory, Inc. Mice were housed in sterile microisolator cages supplied with sterile bedding, food, and water all given ad libitum. The UAB CT strain of M. pulmonis was administered intra-nasally to induce infection. Murine anti-IL-17A (αIL-17A) neutralizing antibody was administered intraperitoneal at a concentration 0.150 mg/mL daily. Results were analyzed via one-way and two-way ANOVA. Results (c): After administration of αIL-17A, BALB/c mice infected with M. pulmonis lost less weight when compared to identical mice given Phosphate Buffered Saline (PBS). In addition, infected mice given antibody displayed a reduction in gross lung lesions, however, bacterial burden was not affected. In contrast, infected C57BL/6 mice given αIL-17A antibodies demonstrated increased disease susceptibility associated with an increase in bacterial burden and gross lung lesions when compared to controls given PBS. Conclusions (d): While the presence of αIL-17A in infected BALB/c mice appears to exacerbate disease, this cytokine may play a protective role in C57BL/6 mice infected with the same pathogen. Lung damage decreased, independent of bacterial burden, in infected BALB/c mice administered antibody. This demonstrates that IL-17A does not play a role in pathogen clearance, but does potentiate chronic inflammation. In contrast, infected C57BL/6 mice given antibody had a slight increase in both lung damage and bacterial numbers indicating that IL-17A is needed to decrease disease pathogenesis. Thus, genotypic differences may play a role in how IL-17A influences an immune response through favoring the development of chronic diseases during bacterial infection.Item Interleukin-17A (IL-17A) worsens severe murine respiratory mycoplasma disease(2018-08-01) Mize, Maximillion; Jerry W. Simecka; Rance E. Berg; Harlan P. JonesThe purpose of these studies was to determine the role of Interleukin-17A (IL-17A) in the immune response to respiratory mycoplasma infection. Serum levels of IL-17A increase in disease-susceptible BALB/c mice, but not disease-resistant C57BL/6 mice, infected with Mycoplasma pulmonis. Increased serum IL-17A was associated with mycoplasma pathology during infection in BALB/c mice, including: the presence of pulmonary neutrophils, progressive weight loss, and the development of inflammatory lung lesions. Neutralizing the function of IL-17A using monoclonal anti-IL-17A antibodies during mycoplasma infection reduced disease severity in disease-susceptible BALB/c mice, but not disease-resistant C57BL/6 mice. Providing daily intra-peritoneal injections of anti-IL-17A antibodies to BALB/c mice infected with M. pulmonis was effective at reducing weight loss, the prevalence of clinical signs, and the incidence of gross lesions. Histological lesions, characterized by the presence of pulmonary neutrophils, were also lower in infected BALB/c mice receiving anti-IL-17A antibodies daily. Bacterial burden remained unaffected in mice regardless of treatment. Neutralizing IL-17A throughout infection was effective at reducing late mycoplasma pathology, a period influenced by the actions of adaptive immunity and this is supported by a reduction in disease severity when infected BALB/c mice were provided intra-peritoneal injections of anti-IL-17A antibodies only after T-cells infiltrate the lungs. Pulmonary T-cells, specifically CD4+ T-helper (Th17) cells, were the primary source of IL-17A throughout infection with M. pulmonis in disease-susceptible BALB/c mice. Although Th17 cells increased in the lung after infection, the Th17 response did not reach its peak until the later stages of infection and coincided with when the neutralization of IL-17A started to reduce the severity of disease. IL-17A+ T-cells did not express Retinoic Acid Related (RAR) Orphan Receptor-γt (RORγt), a signature Th17 transcription factor, after infecting BALB/c mice with M. pulmonis and suggests that RORγt is not a suitable marker to identify the IL-17A+ T-cells worsening mycoplasma disease. The effect of neutralizing IL-17A was mimicked in disease-susceptible BALB/c mice depleted of neutrophils during M. pulmonis infection. Depleting neutrophils in BALB/c mice infected with M. pulmonis abrogated weight loss while reducing the appearance of both clinical signs and gross lesions. IL-17A promotes pathology during disease utilizing various mechanisms, one of which is to mobilize and activate neutrophils; however, the IL-17A failed to worsen mycoplasma disease in the absence of neutrophils during M. pulmonis infection in BALB/c mice. These results suggest that IL-17A relies only upon neutrophil recruitment and activation to exacerbate mycoplasma disease. Supporting this, combining the neutralization of IL-17A with the depletion of neutrophils failed to lessen disease severity beyond what either treatment could achieve alone. These findings underscore IL-17A or neutrophils as targets for inhibition to reduce the severity of disease during mycoplasma infection. Both IL-4 and IL-17A increase in the lungs of BALB/c mice infected with M. pulmonis and there are Th17 cells that secrete IL-4. In STAT6 KO mice that respond poorly to IL-4 and generate defective Th2-mediate immunity, neutralizing IL-17A also reduced inflammatory damage during M. pulmonis infection. Treating STAT6 KO mice with anti-IL-17A antibodies during M. pulmonis infection reduced weight loss, the prevalence of clinical signs, and incidence of inflammatory lesions. Like wild-type mice, the pathologic effect of IL-17A manifested during the later stages of M. pulmonis infection in STAT6 KO mice and coincided with the activation of adaptive immunity. Neutralizing IL-17A also failed to change mycoplasma numbers during infection in STAT6 KO mice. IL-17A is highlighted as an independent contributor to mycoplasma pathology with no impact on mycoplasma clearance; inhibiting the activation of Th2- and Th17-mediated immune responses could increase resistance by permitting the development of protective responses during infection. This work emphasizes the importance of IL-17A and Th17 cells as an autonomous immune response worsening neutrophil-mediated pathology during late mycoplasma infection in susceptible mice. Monoclonal antibodies that neutralize the function of IL-17A could reduce the severity of disease during mycoplasma infection in man and animals. Directly targeting neutrophils may also lessen the negative impact IL-17A has on mycoplasma pathology. Vaccines that do not activate IL-17A-mediated immunity could reduce the susceptibility to mycoplasma infection and allow for the development of immune responses that lead to mycoplasma clearance. IL-17A functions to worsen disease severity without impacting mycoplasma clearance, and so IL-17A is identified as a contributor to pathology during infection.