@phdthesis{Klein2015, author = {Klein, Dennis}, title = {The pathogenic role of endogenous antibodies in a mouse model for Charcot-Marie-Tooth 1B neuropathy}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-121941}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2015}, abstract = {Charcot-Marie-Tooth (CMT) type 1 neuropathies are a genetically heterogeneous group of non-treatable inherited disorders affecting the peripheral nervous system that lead to sensory and motor dysfunction. Secondary low grade inflammation, implicating the innate and adaptive immune system, could previously be identified as a substantial disease modifier in two mouse models for CMT1, CMT1B and 1X, respectively. However, the exact mechanism how the adaptive immune system contributes to disease pathogenesis is not completely understood. Based on observations that the accumulation of endogenous antibodies to myelin components is important for rapid myelin clearance after nerve injury during Wallerian degeneration, a possibly similar mechanism was considered for endogenous antibodies as disease amplifier in mice heterozygously deficient for P0 (P0het), mimicking some typical features of CMT1B. In this study an increased antibody deposition was detected in the affected peripheral nerves of P0het myelin mutant mice. By crossbreeding P0het mutants with mice specifically lacking B-lymphocytes, and therefore antibodies (JHD-/-), a decline of endoneurial macrophages together with a substantially ameliorated demyelination could be demonstrated in 6-month-old mutant mice. Moreover, reconstitution with murine IgGs reverted the neuropathic phenotype, substantiating that endogenous antibodies are potentially pathogenic at this early stage of disease. Unexpectedly, in 12-months-old P0het mutants, JHD deficiency resulted in disease aggravation accompanied by an increased inflammatory reaction and M2-polarized macrophage response. These observations suggest that in a mouse model for CMT1B, the lack of endogenous antibodies has a dichotomous effect: ameliorating early macrophage-mediated demyelination, as opposed to increasing inflammatory reactions leading to disease aggravation at older ages.}, subject = {Maus}, language = {en} } @phdthesis{Krueger2021, author = {Kr{\"u}ger, S{\"o}ren}, title = {Unterschiedliche Einfl{\"u}sse von Komplement auf Reaktionen neutrophiler Granulozyten auf die Infektion mit \(Neisseria\) \(meningitidis\)}, doi = {10.25972/OPUS-24969}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-249697}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {The gram-negative diplococcus Neisseria meningitidis (Nme) is a frequent human-specific, commensal bacterium of the upper respiratory tract. Under certain conditions especially in infants, meningococci can translocate into the bloodstream and cause invasive meningococcal disease (IMD) manifesting as meningitis or sepsis or a combination of both. IMD is feared for its rapid progression and high fatality rate if it remains untreated. IMD affects up to one million people annually causing substantial morbidity and mortality worldwide. It is well-established that the complement system is an important protective factor in meningococcal disease through opsonization of bacteria with C3b and the lytic activity of the membrane attack complex although the inflammatory C5a/C5aR1 axis can aggravate IMD. The role of neutrophil granulocytes in meningococcal infection is less clear despite their abundant recruitment throughout the course of disease. This study aimed to characterize neutrophil responses to Nme in vitro and the influence of complement on these responses. In infection assays with whole blood and isolated PMNs, effective binding, internalization and killing of Nme by neutrophils was demonstrated. A significant complement-dependence of neutrophil phagocytosis and oxidative burst was observed. The opsonizing and lytic pathway of the complement cascade were found to be most relevant for these responses since blockade of C3 using inhibitor Compstatin Cp20 reduced phagocytosis and oxidative burst significantly more than the blockade of the inflammatory branch with C5aR1-antagonist PMX53. Opsonization with specific antibodies could not replicate the effect of complement activation indicating that engagement of neutrophil complement receptors, particularly complement receptor 3, is involved. Other neutrophil effector functions such as degranulation and IL-8 release were activated in a complement-independent manner implying activation by other inflammatory signals. Considering existing evidence on the overall protective effect of PMNs, further studies investigating the contribution of each neutrophil effector function to infection survival in vivo are required. Ideally, this should be studied in a murine meningitis or sepsis model in the context of complement activation.}, subject = {Neisseria meningitidis}, language = {en} }