Immunology
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12503/21762
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Browsing Immunology by Author "Simecka, Jerry"
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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 PRELIMINARY EXPERIMENTS IN THE DEVELOPMENT OF A HUMANIZED MOUSE MODEL OF MYCOPLASMA PNEUMONIAE(2014-03) Chikelue, Calvin I.; Mize, Maximillion T.; Simecka, JerryThe contribution of Mycoplasma pneumoniae to infections leading to community-acquired pneumonia (CAP) makes it a prime bacterium to study for the development of protective vaccines against it. Despite this, the scant few vaccines researched and tested offer little to no immune protection. In order to further along development of a protective vaccine, the human immune response to M. pneumoniae infection needs to be appropriately deduced. Our lab seeks to develop a humanized mouse model for M. pneumoniae which can be used for observing the most likely human immune response to this bacterium. These preliminary experiments revolve around the investigating the infectivity and pathogenicity of three different strains: S1, M129, and UABPO1. Whichever strain exhibits the ability to cause severe disease within our test animals in comparison to the others will be the strain we utilize in our future studies. These strains were used to infect multiple groups of Balb/c mice which were observed over 14 day time period. At the conclusion of the time period, the mice were sacrificed and the lungs were scored for lung lesions and afterward, depending on the experimental group, the lungs were either homogenized for dilution plating or stored in fixative for histological staining. As of this point in our precursory experimentation, the UABPO1 strain has shown the most promising results in terms of its pathogenicity in comparison to the other experimental strains and may be the strain our lab will utilize in the future studies for developing the humanized mouse model. Purpose (a): Community-acquired pneumonia (CAP) is a lung disease caused by infection with a respiratory bacterium. M. pneumoniae, a major contributor to CAP infections, is a bacterium that invades and attaches to the airway epithelium causing damage to the host through the production toxic substances or Community Acquired Respiratory Distress Syndrome (CARDS) toxin. No commercial vaccine currently exists for the bacterium and tested vaccines have shown to be more immunopathologic rather than protective. To develop a protective vaccine, the immune response against M. pneumoniae must be better understood. Our research is focused on the development of a humanized mouse model for the study of the immune mechanisms that occur during and infection with M. pneumonia. Methods (b): Three strains are used in these preliminary experiments: S1, M129, and UABPO1. Whichever strain causes severe disease within mice will be used in the future experiments with the model. Groups of Balb/c mice were inoculated intranasally with 20 to 40 uL of bacteria from cultured stocks. A fourth control group was included. Infected animals were observed for 14 days and clinical signs were documented. At the end of period, the mice were sacrificed and lungs harvested and scored for lung lesions. Harvested lungs were either homogenized for dilution plating on agar or stored in fixation solution for histological staining. Results (c): Studies were done using older mice, different dosages of mycoplasmas, and incubating thawed bacterial stocks to allow the organism to recover from their frozen state prior to inoculation. Each of these changes appeared to increase disease severity. In particular, mice infected with UABPO1 strain of mycoplasma developed more severe disease compared with the other tested strains of mycoplasma. Conclusions (d): At this point in our studies, we have seen that UABPO1, in comparison with the strains of mycoplasma, may be the most promising for use in further experiments developing the humanized mouse model. Future experiments will observe bacterial load within infected animals at several different time points since it is possible that bacterial clearance is occurring during by the end of the 14 day time course. As well as repeat studies in immunodeficient and humanized mice.