The process of β-cell destruction that leads to type 1 diabetes (T1D) is incompletely understood and it is believed to be a result of both genetic and environmental factors. Enterovirus (EV) infections of the β-cells have been proposed to be involved, however, the effects of EV infections on human β-cells have been little investigated. This thesis summarises studies of three different Coxsackie B4 virus strains that have previously been shown to infect human islets. The effects of infections with these EV were studied in vitro in human islets and in a rat insulin-producing cell line. In addition, a pilot study was performed on isolated human islets to investigate the ability to treat such infections with an antiviral compound. It was found that one of the virus strains replicated in human β-cells without affecting their main function for at least seven days, which in vivo may increase a virus’s ability to persist in islets. Nitric oxide was induced by synthetic dsRNA, poly(IC), but not by viral dsRNA in rat insulinoma cells in the presence of IFN-γ, suggesting that this mediator is not induced by EV infection in β-cells and that poly(IC) does not mimic an EV infection in this respect. All three virus strains were able to induce production of the T-cell chemoattractant interferon-γ-inducible protein 10 (IP-10) during infection of human islets, suggesting that an EV infection of the islets might trigger insulitis in vivo. Antiviral treatment was feasible in human islets, but one strain was resistant to the antiviral compound used in this study. To conclude, a potential mechanism is suggested for the involvement of EV infections in T1D. If EV infections induce IP-10 production in human islet cells in vivo, they might recruit immune cells to the islets. Together with viral persistence and/or virus-induced β-cell damage, this might trigger further immune-mediated β-cell destruction in vivo.

It has been suggested that the rising amounts of chemicals in the environment may affect host resistance and increase susceptibility to infections. Studies have also shown that infections can change the toxicity of pollutants. The aim of this thesis was to study interactions between environmental pollutant exposure in terms of polybrominated diphenyl ethers (PBDE) and a common human coxsackievirus B3 (CVB3) infection adapted to Balb/c mice. The studies focused on virus levels, cytokines, metabolising cytochrome P450 (CYP) enzymes and tissue distribution of PBDE. A novel finding was an organ-specific effect of CVB3 infection on the metabolising capacity of PBDE. The PBDE metabolising enzyme CYP2B10 was down-regulated by the CVB3 infection in the liver, up-regulated in the lungs, but not affected in the pancreas. Accordingly, CVB3 infection increased the concentration of PBDE in the livers of infected mice. However, serum levels of PBDE were not affected by the infection, indicating that serum does not reflect the actual organ exposure of PBDE in infected individuals. The change in metabolising capacity was likely mediated by infection-induced cytokines and associated effects on the nuclear factor-κB (NF-κB) pathway. PBDE drastically decreased serum levels of several cytokines and chemokines, an event that may create a slot for viruses to replicate. Accordingly, some results show that infected mice exposed to a high dose of PBDE had higher virus levels than mice exposed to a low dose. In conclusion, infected individuals showed organ-specific changes in metabolism and tissue levels of PBDE, which potentially could change the toxicity of PBDE. PBDE also seems to affect the fate of the infection. NF-κB activated pathways may mediate one possible mechanism underlying these effects. Thus, further investigations of this pathway are warranted. In addition, future studies should address how PBDE exposure affects viral replication.

Hypothermia therapy (HT) is used clinically following global cerebral ischemia (GCI) but its therapeutic mechanisms are not completely understood. An elucidation of such mechanisms may lead to novel therapeutic approaches that improve patient outcome. Using a murine model of GCI, we determined the effect of HT on the expression of inflammatory proteins in the hippocampus and serum. We also examined its effect on microglia/macrophage activation and neurodegeneration in the brain at 72 hours following ischemia, and its effect on long-term spatial memory/learning and contextual fear response. GCI led to increased neurodegeneration and microglia/macrophage activation in the hippocampus, and increased IL-1β and KC protein expression in the hippocampus at 72 hours. Hypothermia therapy attenuated these inflammatory responses. It also improved spatial learning/memory at 7 and 21 days, and preserved contextual fear response 21 days post-ischemia. Hypothermia therapy attenuated the post-ischemic inflammatory response, protected hippocampal neurons, and preserved long-term memory and learning.

Hypothermia therapy (HT) is used clinically following global cerebral ischemia (GCI) but its therapeutic mechanisms are not completely understood. An elucidation of such mechanisms may lead to novel therapeutic approaches that improve patient outcome. Using a murine model of GCI, we determined the effect of HT on the expression of inflammatory proteins in the hippocampus and serum. We also examined its effect on microglia/macrophage activation and neurodegeneration in the brain at 72 hours following ischemia, and its effect on long-term spatial memory/learning and contextual fear response. GCI led to increased neurodegeneration and microglia/macrophage activation in the hippocampus, and increased IL-1β and KC protein expression in the hippocampus at 72 hours. Hypothermia therapy attenuated these inflammatory responses. It also improved spatial learning/memory at 7 and 21 days, and preserved contextual fear response 21 days post-ischemia. Hypothermia therapy attenuated the post-ischemic inflammatory response, protected hippocampal neurons, and preserved long-term memory and learning.

The increase in ASMC mass is a major structural change described in airway remodeling in asthma. This increase has been attributed to ASMC hyperplasia and hypertrophy. The distance between ASMC and the epithelium is reduced suggesting expansion of the muscle bundle towards the epithelium. Recent studies have suggested a role of epithelial derived chemokines in ASMC migration toward the epithelium. We hypothesized that chemokines (Eotaxin, RANTES, MIP-1alpha and IL-8) can directly influence ASMC mass by increasing the rate of proliferation or enhancing survival. ASMCs were exposed to different concentrations of eotaxin, RANTES, IL-8 or MIP-1alpha. To test for proliferation, stimulated ASMC were pulsed with 3H-thymidine or stained with BrdU and then analyzed with flow cytometry. Apoptosis was measured using Annexin V and flow cytometry. Expression of phosphorylated p42/p44 and MAPKinases was assessed by Western analysis. In a concentration-dependent manner, chemokines such as Eotaxin, RANTES, IL-8 and MIP-lalpha increased ASMCs 3H-thymidine incorporation and DNA synthesis. Eotaxin, RANTES and IL-8 decreased the number of apoptotic ASMCs compared to the matched controls. A significant increase in phosphorylated p42/p44 MAPKs was seen after treating ASMCs with RANTES and eotaxin. We conclude that chemokines might contribute to airway remodeling by increasing the number of ASMCs.

No abstract available. / Thesis (Ph.D.)-University of KwaZulu-Natal, Piertermaritzburg, 2010.

Clinical islet transplantation is today an established alternative treatment for a selected group of type 1 diabetes patients. The predominant technique for transplantation is infusion of islets in the liver via the portal vein. Obstacles to advancing islet transplantation include limited engraftment resulting from an immediate blood-mediated inflammatory reaction (IBMIR), a life-long need for immunosuppression and the shortage of organs available. In this thesis, innate and adaptive immunity were explored in allogeneic and xenogeneic settings, with the long-term goal of preventing islet graft destruction. Methods for studying immune responses to islets in blood and engrafted islets in liver tissue (intragraft gene expression) were developed and refined. The innate response to human islets and exocrine tissue in ABO-compatible blood was characterized up to 48 h using a novel whole-blood model. Physiological changes in the blood during incubations were explored and adjusted to allow prolonged experiments. Increased production of chemokines targeting CXCR1/2, CCR2 and CXCR3 was observed, accompanied by massive intra-islet neutrophil infiltration. Notably, endocrine and exocrine tissue triggered a similarly strong innate immune response. Two studies of adult porcine islet transplantation to non-human primates (NHPs) were performed. Expression of immune response genes induced in liver tissue of non-immunosuppressed NHPs (≤72 h) was evaluated after porcine islet transplantation. Up-regulation of CXCR3 mRNA, together with IP-10, Mig, MIP-1α, RANTES, MCP-1 and cytotoxic effector molecule transcripts, was associated with T-cell and macrophage infiltration at 48-72 h. Long-term survival (>100 days) of adult porcine islets in a NHP model was later demonstrated using T-cell-based immunosuppression, including co-stimulatory blockade (anti-CD154 mAb). Graft failure was associated with increased levels of circulating, indirectly activated T cells, non-Gal pig-specific IgG and gene transcripts of inflammatory cytokines. Microarray analysis of the response to inflammatory cytokines in cultured porcine islets identified genes involved in cell death, immune responses and oxidative stress; this gene pattern coincided with physiological changes (decrease in insulin and ATP content). In summary, allogeneic whole-blood experiments and xenogeneic in vivo studies underscored the importance of preventing early inflammation and cell-recruitment to avoid islet graft loss in islet transplantation. Long-term survival of porcine islets in NHPs was shown to be feasible using T-cell-directed immunosuppression, including anti-CD154 mAb.

No description available.

Diss. (sammanfattning) Stockholm : Karol. inst., 2006. / Härtill 4 uppsatser.

Thesis (Ph.D.)--University of Florida, 2004. / Typescript. Title from title page of source document. Document formatted into pages; contains 100 pages. Includes Vita. Includes bibliographical references.