Browsing by Subject "immunity"
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Item EFFECTS OF HOST IMMUNITY ON ANTIBIOTIC TREATMENT OF STAPHYLOCOCCUS AUREUS BIOFILM INFECTIONS(2013-04-12) McDougal, AprilPurpose: Staphylococcus aureus is a pathogen often seen in the hospital setting and the cause of various infections in humans. Multiple antibiotic resistant S. aureus strains (MRSA) have been clinically isolated, which becomes problematic when S. aureus forms biofilms or slime layers on synthetic materials like catheters. Biofilm infections are difficult to treat, and if a patient has compromised immunity due to underlying medical conditions, the infection can be life threatening. To understand the impact of host immunity on the treatment of S. aureus biofilm infections, we subcutaneously (SC) implanted S. aureus infected catheter pieces in mice that have severe combined immunodeficiency (SCID), treated them for 7 days with rifampin, and measured the number of rifampin-resistant and rifampin-sensitive cells associated with the catheter pieces. Methods: Using broth media supplemented with glucose and sodium chloride, 1 cm Teflon catheters were inoculated with a non-resistant strain of S. aureus for one hour. Infected catheters were surgically placed subcutaneously in four mouse strains, BALB/c, BALB/c-SCID, C57BL/6J and C57BL/6J-SCID. Seven days after implantation, an antibiotic regimen was started using either rifampicin or vehicle, 2 times a day for 7 days. The catheters were aseptically removed within 20 hours of the final dose. The catheters were processed and plated on non-antibiotic agar media and media containing 1 mg/mL of rifampin. Results: Catheter-associated CFU stabilized at 6.3 log CFU in C57BL/6J mice and 7.4 log CFU in BALB/c mice 14 days after implantation. Rifampin 7-day treatment at 25mg/kg yielded mean log CFU reductions of 1.8 and 2.6 in BALB/c wild-type and SCID mice, respectively. The same treatment resulted in mean log CFU reductions of 2.3 and 2.7 in C57BL/6J wild-type and SCID mice, respectively. Rifampin resistant isolates (1mg/mL) were recovered at a mean log CFU of 3.8 and 2.6 in C57BL/6J wild-type and SCID mice, respectively. Conclusions: SCID mice are lymphocyte deficient and have an impaired adaptive immune response. Our data shows that the reduced immunity enhances rifampin's ability to treat the S. aureus biofilm infection, while reducing the frequency of rifampin-resistance in the model. Therefore, our data suggests that the host's immune response can influence an antibiotic's ability to treat S. aureus biofilm infections.Item Signaling in Natural Killer Cells: NK Cell Activation by LLT1 Receptor(2008-05-01) Bambard, Nowland D.; Jerry Simecka; Richard Easom; Harlan JonesBambard, Nowland D., Signaling in Natural Killer Cells: NK Cell Activation by LLT1 Receptor. Doctor of Philosophy (Microbiology and Immunology), May 2008, 162 pp., 1 table, 30 illustrations, bibliography, 179 titles. Natural Killer (NK) cells are large granular lymphocytes of the innate immune system that constitute the first line of defense against viral pathogens and cancer. Unlink cells of the adaptive immune response, NK cells do not recognize specific antigens expressed on MHC receptors, rather they recognize tumorgenic and virally infected cells through a complex balance of activating and inhibiting receptors expressed on the surface of human NK cells. LLT1 is expressed on numerous immune cells and subsequent functional analysis indicates that LLT1 plays an activating role on NK cells by way of stimulating interferon-gamma (IFN-G) secretion. LLT1 has also been shown to have a role on non-immune cells, inhibiting the formation and function of osteoclasts. Additionally, the natural ligand of LLT1 has been identified as NKR-P1A (CD161), an NK cell inhibitory receptor known to play an important role in immune regulation. We hypothesize that LLT1 employs multiple signaling pathways to accomplish its activating functions on human NK cells, and may be associated with one of four known transmembrane accessory proteins associated with NK cell activating receptors. We activated LLT1 on NK92 cells with target cells expressing its natural ligand CD161 and analyzing IFN-G production in the presence of pharmacological inhibitors specific for various signaling mechanisms. These results indicate that LLT1 employs Src-PTK, p38 and ERK signaling pathways, but not PKC, P13K or calcineurin. These results were followed up with phosphorylation analysis, which confirmed that the ERK signaling pathway is associated with LLT1 IFN-G production. Finally, by analyzing IFN-G mRNA we found that LLT1 activation is not associated with any detectable change in IFN-G mRNA levels, suggesting that LLT1 stimulates NK IFN-G production by modulating post transcriptional or translational events. Identification of the signaling pathways associated with LLT1 is of great medical significance as this may provide us with novel insights into activating NK cells to counter infection and cancer.Item T-Helper Cell Responses in Lungs After Immunization and Chronic Respiratory Disease; And Their Association With Pulmonary Inflammation(2001-05-01) Jones, Harlan P.; Simecka, Jerry; Dimitrijevich, S. Dan; Goldfarb, Ronald H.The purpose of these studies was to characterize T helper cell responses in the lungs of mice after immunization and chronic respiratory infection. CD4+ T cells were the major population of T cells resident in the lung in comparison to CD8+ T cells. Polyclonal activation of resident CD4+T cells produced abundant levels of IL-4 in comparison to IFN-γ, indicating that Th2 cells were the major sub-population of CD4+ T cells. In contrast, resident CD8+ T cells were the sole producer of IFN-γ by naïve T lymphocytes. Furthermore, the distribution of T cells was similar between BALB/c, C3H/HeN, C57BL/6 and DBA/2N strains of mice. However differences in the distribution of CD8+T cells, as well as the levels of IL-4 and IFN-y production produced by resident T cells were found between C57 and the other strains of mice tested. These results demonstrate that host genetic factors may be involved in determining host susceptibility to respiratory disease. Differences in the intensity of antigenic stimulation provoke changes in the type of T cell response generated. Intranasal immunization with influenza (FLU) vaccine antigen alone initiated solely an antigen-specific Th2-like response. In contrast, the addition of the potent mucosal adjuvant cholera toxin (CT) in combination with FLU antigen induced not only resident Th2 responses, but also induced antigen-specific Th1-like responses. This change corresponded with a dramatic increase in the number of CD4+ T cells in the lung. Thus, intense immunization of respiratory T cells enhanced resident T helper cell responses, but also promoted the activation of Th1 responses. Chronic respiratory infection also elicited changes in the resident population of T cells consistent with pulmonary inflammatory immune responses. At early stages of infection, CD4+, but not CD8+ T cells increased in number within inductive respiratory lymphoid tissues (lower respiratory nodes [LRNs]). Between day 7 and 14 however, there was a dramatic increase in the number of CD4+ T cells in the lung. Interestingly, CD8+ T cells also increased in the lungs, suggesting their activation along mucosal sites during mycoplasma infection. Mycoplasma-specific IL-4 and IFN-γ production also increased in a tissue-specific/time-dependent manner. IL-4 production was initially observed in the LRNs, whereas significant levels of IL-4 and IFN-γ was produced in both tissues 14 days after infection. In comparison, IFN-γ was the predominate cytokine, produce at 14 days coinciding with pulmonary inflammation. Suggesting that intense activation promoted changes in the resident pulmonary Th2 environment, and possible is a major component of pulmonary inflammatory immune responses. Both CD4+ and CD8= T cells were shown to have a role in modulation of disease severity during mycoplasma disease. Observation of gross pulmonary lesions reveal that mycoplasma infected mice treated with anti-CD8 antibody showed increase clinical signs of disease and pronounced gross pulmonary lesions. Additionally the number of total mononuclear cells increased dramatically in the absence of CD8+ T cells. Thus, CD8+ T cells may have a regulatory role in controlling resident CD4+ T cells that increased 14 days after infection. Chemokine production is known to mediate the recruitment of lymphocytes to enhance the initiation of immunity as well as be responsible for modulating inflammatory responses. We find that mycoplasma increase the number of dendritic cells in the lung 14 days after infection, and stimulated the production of dendritic cell-derived ABCD-1 chemokine. Also, β-chemokine MIP-1α and MIB-1β production was observed during intense immunization as well as during mycoplasma infection. These results provide evidence for a potential mechanism through which changes in resident pulmonary T cell responses occur given the intensity of the immune response generated.Item The Effect of Lymphatic Pump Treatment on Anti-Tumor Immune Responses(2011-05-01) McCauley, Lyndsey R.; Hodge, Lisa M.The lymphatic system’s significance in maintaining health has been focused on by the osteopathic medical profession for years. Osteopathic manipulative treatments (OMT), specifically lymphatic pump techniques (LPT), aim at increasing lymphatic circulation and improving the clearance of interstitial fluid, inflammatory agents, and protein from the interstitial space. However, certain osteopathic manipulative techniques, such as LPT, are contraindicated in the presence of cancer with metastatic potential because it is thought that by accelerating the flow of lymph through the lymphatic vessels, tumor cells may metastasize throughout the body via the lymphatics. However, this theory lacks scientific proof. Studies previously conducted by our lab show that LPT increases thoracic duct lymph flow and leukocyte numbers in the rat and significantly decreases solid tumor formation and increases leukocyte concentrations in the lungs of rats with tumors (unpublished data). It is possible that increased lymph flow along with an increased number of circulating leukocytes can improve immune surveillance, providing recognition of and protection against pathogens and disease. Therefore, we hypothesized that administration of LPT would enhance anti-tumor immune responses in the lungs of rats with pulmonary tumors. In order to test this hypothesis, this thesis focused on one specific aim: to determine if LPT enhances leukocyte activation and/or function, thereby enhancing anti-tumor activities, such as tumor lysis and cytokine secretion.