Grundlage der vorgelegten Arbeit sind die bei der Alzheimerschen Erkrankung beobachtbaren pathologischen Merkmale, wie die progressive Akkumulation von β-Amyloid-Plaques, cholinerger Dysfunktion und zerebrovaskuläre Abnormalitäten. Die in englischer Sprache verfasste Dissertation ist eine tierexperimentelle Studie, die versucht, den Zusammenhang von β-Amyloid, cholinerger Neurotransmission und zerebralem Gefäßsystem bei der Alzheimerschen Erkrankung näher zu charakterisieren. An Hirnmaterial aus der transgenen Maus Tg2576, die die schwedische Mutation des humanen Amyloidpräkursorproteins als Transgen trägt und ab dem 10. Lebensmonat durch humane β-Amyloid-Plaqueablagerungen in der Hirnrinde imponiert, wurden im Altersverlauf (4 bis 18 Monate) immunhistochemische Untersuchungen zur morphologischen Integrität der zerebralen Mikrogefäße, der kortikalen cholinergen Nervterminalen und der intrazerebralen cholinergen neurovaskulären Innervation durchgeführt. Am somatosensorischen Kortex werden beispielhaft die Expression des Glukosetransporters 1 oder Solanum tuberosum Lektin als Kapillarmarker und des vesikulären Acetylcholintransporters als Marker für cholinerge Fasern mittels Immunfluoreszenz und Laser-Scanning Mikroskopie erfasst, einer semiquantitativen Computer-gestützten Bildanalytischen Auswertung unterzogen und mit dem Ausmaß der kortikalen Plaquebeladung korreliert. So konnte gezeigt werden, dass die Dichte der Blutgefäße und cholinergen Fasern im somatosensorischen Kortex von transgenen Tieren mit dem Alter im Vergleich zu nichttransgenen Kontrolltieren abnimmt, was mit einer Reduktion der perivaskulären cholinergen Innervation einhergeht. Die erhobenen Befunde stützen die von J.C. de la Torre und T. Mussivand schon im Jahre 1993 formulierte „vaskuläre Hypothese“, wonach bei der sporadischen Form der Alzheimerschen Erkrankung alters- und Lebensstil-bedingte Schädigungen des zerebralen Gefäßsystems eine zentrale Rolle bei der Manifestierung der Erkrankung spielen.

A nefropatia diabética (ND) decorre da hiperglicemia crônica, de fatores de risco como a hipertensão arterial e a dislipidemia e de uma susceptibilidade genética já evidenciada em inúmeros estudos clínicos. Uma das características histológicas da ND é o acúmulo de proteínas de matriz extracelular no mesângio, para o qual contribuem várias vias bioquímicas. O GLUT-1, codificado pelo gene SLC2A1, é o principal transportador de glucose da célula mesangial e sua expressão está aumentada no glomérulo de animais diabéticos, o que constitui uma alça de feedback positivo pela qual a glicose extracelular aumentada estimula ainda mais sua própria captação, piorando a lesão mesangial. O GLUT-2, codificado pelo gene SLC2A2, é expresso nas células tubulares e nos podócitos e sua expressão também está aumentada na ND. A expressão deste transportador de glicose é regulada pelo fator de transcrição HNF-1. Participa, ainda, da lesão renal induzida pela hiperglicemia o fator de crescimento transformante - (TGF-), que exerce vários efeitos deletérios, tais como diminuir a atividade de metaloproteinases de matriz e promover fibrose renal. Esse fator de crescimento determina a ativação transcricional de genes-alvo, mas necessita de outros ativadores e co-ativadores da transcrição, tais como a proteína SMIF, codificada pelo gene DCP1A. Tendo em vista a participação das proteínas mencionadas acima na patogênese da ND, o presente estudo teve o objetivo de avaliar a associação de polimorfismos de um único nucleotídeo (SNPs) nos genes SLC2A1, SLC2A2, HNF1A, TGFB1 e DCP1A com a doença renal em portadores de diabetes mellitus tipo 1 (DM1). Um total de 449 pacientes (56,4% do sexo feminino, idade média de 36,0±11,0 anos) com mais de 10 anos de doença foram incluídos e classificados de acordo com o estágio de ND: (1) Ausência de ND: excreção urinária de albumina (EUA) normal (< 30 mg/24h ou < 20 g/min) e creatinina plasmática < 1,7 mg/dL sem tratamento anti-hipertensivo; (2) ND incipiente: microalbuminúria (EUA de 30 299 mg/24h ou 20 199 g/min) e creatinina plasmática < 1,7 mg/dL sem tratamento anti-hipertensivo e (3) ND Franca: macroalbuminúria (EUA > 300 mg/24h ou > 200 g/min) ou proteinúria ou tratamento para reposição renal. Também foram avaliadas as associações dos SNPs com o ritmo de filtração glomerular estimado (RFGe). Os SNPs foram genotipados pela metodologia de reação em cadeia da polimerase em tempo real, com o uso de sondas fluorescentes. As associações dos SNPs com a ND foram avaliadas por análise de regressão logística e os odds ratios (OR) e respectivos intervalos de confiança (IC) de 95% foram calculados após ajuste para possíveis confundidores, que foram incluídos como co-variáveis no modelo de regressão. Valores de P < 0.05 (bicaudal) foram considerados estatisticamente significantes. As seguintes associações foram observadas: (1) gene SLC2A1: genótipos CT+TT do SNP rs841848 conferiram risco para a ND incipiente na população global (OR 1,88; CI95% 1,06-3,34; P= 0,03) e nos pacientes do sexo masculino (OR 2,67; CI95% 1,13-6,35; P=0,0247) e para a ND franca (OR 2,70; CI95% 1,18-6,31; e P= 0,0197) apenas nos pacientes do sexo masculino; genótipos GA+AA do SNP rs1385129 conferiram risco para a ND franca na população do sexo masculino (OR 3,09; CI95% 1,34-7,25; P=0,0085); genótipos AT + TT do SNP rs3820589, conferiram proteção contra a ND incipiente na população global (OR 0,36; CI95% 0,16-0,78; P=0,0132) e na população do sexo feminino (OR 0,14; CI95% 0,02-0,52; P=0,0122). (2) gene SLC2A2: genótipos GA+GG do SNP rs5396 conferiram proteção contra ND franca nos pacientes do sexo masculino (OR 0,29; CI95% 0,12-0,69; P=0,0052); os genótipos AG+GG do SNP rs6800180 conferiram proteção contra a ND franca nos pacientes do sexo masculino (OR 0,16; CI95% 0,14-0,90; P=0,0324). (3) gene HNF1A: genótipos AC + CC do SNP rs1169288 conferiram risco para ND franca na população global (OR 2,23; CI95% 1,16-4,38; P=0,0175); genótipos CG+GG do SNP rs1169289 conferiram risco para ND franca na população global (OR 3,43; CI95% 1,61-7,73; P=0,002); (4) Gene TGFB1: genótipos CT + TT do SNP 1800468 conferiram risco para ND incipiente na população total (OR 2,99; CI95% 1,26-7,02; P 0,0116) e o alelo polimórfico T do SNP rs1800469 conferiu risco para um menor RFGe (p=0,0271). (5) gene DCP1A: o alelo polimórfico A do SNP rs11925433 também se associou com um menor RFGe (p=0,0075). Em conclusão, SNPs em genes que codificam as proteínas envolvidas na patogênese da ND GLUT-1, GLUT-2, HNF-1, TGF- e SMIF conferem susceptibilidade para essa complicação crônica nos portadores de DM1 avaliados no presente estudo / Diabetic nephropathy (DN) results from chronic hyperglycemia, risk factors such as hypertension and dyslipidemia as well as from genetic susceptibility, already demonstrated in numerous clinical studies. A histological feature of DN is the accumulation of extracellular matrix proteins in the mesangium after activation of multiple biochemical pathways. GLUT-1, encoded by gene SLC2A1, is the major glucose transporter in mesangial cell and its expression is increased in the glomeruli of diabetic animals, comprising a positive feedback loop whereby high extracellular glucose stimulates its own uptake and worsening mesangial injury. GLUT-2, encoded by SLC2A2 gene, is expressed in podocytes and tubular cells and its expression is also increased in DN. The expression of this glucose transporter is regulated by the transcription factor HNF-1. Transforming growth factor - (TGF-) also participates in renal injury induced by hyperglycemia, exerting several deleterious effects, such as to decrease the activity of matrix metalloproteinases and to promote renal fibrosis. This growth factor determines the transcriptional activation of target genes, but needs other activators and co-activators, such as the protein named SMIF, encoded by the gene DCP1A. Given the involvement of the aforementioned proteins in the pathogenesis of DN, the present study aimed to evaluate the association of single nucleotide polymorphisms (SNPs) in the genes SLC2A1, SLC2A2, HNF1A, TGFB1 e DCP1A with renal disease in patients with type 1 diabetes mellitus (T1DM). A total of 449 patients (56.4% female, mean age 36.0±11.0 years) with disease duration > 10 years were included and grouped according to DN stages: (1) absence of DN: normal urinary albumin excretion (UAE) (< 30 mg/24h or < 20 g/min) and plasmatic creatinine < 1.7 mg/dL without antihypertensive treatment; (2) incipient DN: microalbuminuria (UAE 30 299 mg/24h or 20 199 g/min) and plasmatic creatinine < 1.7 mg/dL without antihypertensive treatment and (3) overt DN: macroalbuminúria (UAE > 300 mg/24h or > 200 g/min) or proteinuria or renal replacement therapy. Associations of SNPs with estimated glomerular filtration rate (eGFR) were also evaluated. All SNPs were genotyped by real time polymerase chain reaction using fluorescent-labelled probes. Associations of the SNPs with DN were assessed by logistic regression analyses and odds ratios (OR) were calculated after adjustments for possible confounders included as covariables in the regressive model. P values <0.05 (two-tails) were considered significant. The following associations were observed: (1) SLC2A1: genotypes CT+TT from rs841848 conferred risk to incipient DN in the overall population (OR 1.88; 95%IC 1.06-3.34; P= 0.03) and in the male patients (OR 2.67; CI95% 1.13-6.35; P=0.0247) and to overt DN (OR 2.70; CI95% 1.18-6.31; e P= 0.0197) only in the male patients; genotypes GA+AA from rs1385129 conferred risk to overt DN in the male population (OR 3.09; CI95% 1.34-7.25; P=0.0085); genotypes AT + TT from rs3820589 conferred protection against incipient DN in the overall population (OR 0.36; CI95% 0.16-0.78; P=0.0132) and in the female population (OR 0.14; CI95% 0.02-0.52; P=0.0122). (2) SLC2A2: genotypes GA+GG from rs5396 conferred protection against overt DN in the male patients (OR 0.29; CI95% 0.12-0.69; P=0.0052); genotypes AG+GG from rs6800180 conferred protection against overt DN in the male patients (OR 0.16; CI95% 0.14-0.90; P=0.0324). (3) HNF1A: genotypes AC + CC from rs1169288 conferred risk to overt DN in the overall population (OR 2.23; CI95% 1.16-4.38; P=0.0175); genotypes CG+GG from rs1169289 conferred risk to overt DN in the overall population (OR 3.43; CI95% 1.61-7.73; P=0.002); (4) TGFB1: genotypes CT + TT from 1800468 conferred risk to incipient DN in the overall population (OR 2.99; CI95% 1.26-7.02; P=0.0116) and the polymorphic allele T from SNP rs1800469 conferred risk to a lower eGFR (p=0.0271). (5) DCP1A: the polymorphic allele A from SNP rs11925433 was also associated with a lower eGFR (p=0.0075). In conclusion, SNPs in the genes encoding proteins GLUT-1, GLUT-2, HNF-1, TGF- e SMIF, all involved in the pathogenesis of DN, conferred susceptibility to this chronic complication in the T1DM patients evaluated in the present study

Grundlage der vorgelegten Arbeit sind die bei der Alzheimerschen Erkrankung beobachtbaren pathologischen Merkmale, wie die progressive Akkumulation von β-Amyloid-Plaques, cholinerger Dysfunktion und zerebrovaskuläre Abnormalitäten. Die in englischer Sprache verfasste Dissertation ist eine tierexperimentelle Studie, die versucht, den Zusammenhang von β-Amyloid, cholinerger Neurotransmission und zerebralem Gefäßsystem bei der Alzheimerschen Erkrankung näher zu charakterisieren. An Hirnmaterial aus der transgenen Maus Tg2576, die die schwedische Mutation des humanen Amyloidpräkursorproteins als Transgen trägt und ab dem 10. Lebensmonat durch humane β-Amyloid-Plaqueablagerungen in der Hirnrinde imponiert, wurden im Altersverlauf (4 bis 18 Monate) immunhistochemische Untersuchungen zur morphologischen Integrität der zerebralen Mikrogefäße, der kortikalen cholinergen Nervterminalen und der intrazerebralen cholinergen neurovaskulären Innervation durchgeführt. Am somatosensorischen Kortex werden beispielhaft die Expression des Glukosetransporters 1 oder Solanum tuberosum Lektin als Kapillarmarker und des vesikulären Acetylcholintransporters als Marker für cholinerge Fasern mittels Immunfluoreszenz und Laser-Scanning Mikroskopie erfasst, einer semiquantitativen Computer-gestützten Bildanalytischen Auswertung unterzogen und mit dem Ausmaß der kortikalen Plaquebeladung korreliert. So konnte gezeigt werden, dass die Dichte der Blutgefäße und cholinergen Fasern im somatosensorischen Kortex von transgenen Tieren mit dem Alter im Vergleich zu nichttransgenen Kontrolltieren abnimmt, was mit einer Reduktion der perivaskulären cholinergen Innervation einhergeht. Die erhobenen Befunde stützen die von J.C. de la Torre und T. Mussivand schon im Jahre 1993 formulierte „vaskuläre Hypothese“, wonach bei der sporadischen Form der Alzheimerschen Erkrankung alters- und Lebensstil-bedingte Schädigungen des zerebralen Gefäßsystems eine zentrale Rolle bei der Manifestierung der Erkrankung spielen.:CHAPTER 1: INTRODUCTION 1.1 Alzheimer’s disease 1 1.2 APP processing and β-amyloid production 2 1.3 Cholinergic dysfunction in Alzheimer’s disease 5 1.4 Cerebrovascular abnormalities in Alzheimer’s disease 8 1.5 Cholinergic innervation of intracortical cerebral microvessels 9 1.6 Transgenic Tg2576 mouse model of Alzheimer’s disease 11 1.7 Aim of study 14 CHAPTER 2: MATERIALS AND METHODS 2.1 Materials 15 2.1.1 Chemical reagents used 15 2.1.2 Biological reagents used 15 2.1.3 Preparation of solutions and buffers 15 2.1.4 Antibodies and reagents used for immunohistochemistry 17 2.1.5 Transgenic animals 19 2.2 Methods 20 2.2.1 Tissue preparation and sampling of sections 20 2.2.2 Immunohistochemistry 20 2.2.2.1 Protocol of immunofluorescent labeling 20 2.2.2.2 Protocol of immunoperoxidase labeling (ABC technique) 21 2.2.2.3 Combination of primary and secondary antibodies 22 2.2.2.4 Protocol of β–amyloid immunolabeling (Formic acid epitope retrieval method) 23 2.2.3 Histochemistry 23 2.2.3.1 Thioflavin S staining 23 2.2.3.2 Nissl staining 23 2.2.3.3 Solanum Tuberosum Lectin (STL) staining 24 2.2.4 Double and triple-coloured immuno-/ histochemical staining of brain sections 24 2.2.5 Microscopy and digital image processing 25 2.2.6 Morphological and morphometric analyses 25 2.2.6.1 Cortical microvessels 25 2.2.6.2 Cortical cholinergic innervation 27 2.2.6.2.1 Total density of VAChT-immunoreactivity 27 2.2.6.2.2 Estimation of the density of varicosities on cholinergic fibres 29 2.2.6.3 Estimation of cholinergic perivascular innervation of cortical microvessels 29 2.2.6.4 Three-dimensional-imaging of vessels innervation 30 2.2.7 Statistical analysis 30 CHAPTER 3: RESULTS 3.1 Developmental and amyloid plaque-related changes in cerebral cortical capillaries in transgenic Tg2576 Alzheimer mice 31 3.1.1 Morphological distribution of brain vessels in the cerebral cortex of wild type mice 31 3.1.2 Microvessel density under plaque burden 33 3.2 Developmental and amyloid plaque-related changes in cholinergic neurotransmission in cholinoceptive target regions of transgenic Tg2576 mice 39 3.2.1 Visualisation of cholinergic nerve terminals in mouse brain 39 3.2.2 VAChT-Expression in wild type and transgenic Tg2576 mice 40 3.3 Role of cholinergic system in β-amyloid-related changes in the cerebrovascular system of transgenic Tg2576 mice 46 3.3.1 Solanum tuberosum lectin (STL) histochemistry in visualisation of brain vessels, β-amyloid, and microglia 46 3.3.1.1 Solanum tuberosum lectin and brain vessels 46 3.3.1.2 Solanum tuberosum lectin and β-amyloid plaques 47 3.3.1.3 Solanum tuberosum lectin staining to visualize glial cells 48 3.3.2 Cholinergic perivascular innervation of cerebral cortical microvessels in transgenic Tg2576 and wild type mice 50 CHAPTER 4: DISCUSSION 4.1 β-Amyloid and brain vascular system: the vascular hypothesis of Alzheimer’s disease 55 4.1.1 Evidences of a role of vascular mechanisms in Alzheimer’s disease 55 4.1.2 Effect of β-amyloid on brain vascular system 57 4.1.3 Effect of ischemia and hypoperfusion on APP processing 59 4.1.4 Effect of β-amyloid on cholinergic function in brain vascular system 59 4.2 Aim of study and main results obtained 61 4.3 Age-related changes in cerebral cortical microvessels in the presence and absence of β-amyloid plaque load 62 4.4 Age-related changes of cholinergic terminals in cholinoceptive target regions in the presence and absence of β-amyloid plaque load 64 4.4.1 VAChT – a reliable marker for detection of cholinergic terminals in cerebral cortex 64 4.4.2 The barrel field of the somatosensory cortex 1 (S1BF) as a model region to reveal age-related changes in cholinergic innervation 65 4.4.3 VAChT expression: morphological and morphometric studies 66 4.5 Age-related changes in cholinergic innervation of cerebral cortical microvessels in the presence and absence of β-amyloid plaque load 69 4.5.1 STL – a mono-marker for detection of cortical vessels, senile amyloid plaques and activated microglia in cerebral cortex 69 4.5.2 Cholinergic perivascular innervation of cerebral cortical microvessels in transgenic Tg2576 mice 70 4.5.3 Quantitation of cholinergic input on cerebral microvessels of mouse brain 71 4.6 Summary and conclusions 75 REFERENCES 77