Project description:Amyloid-ß (Aß) plaques are pathological hallmarks of Alzheimer disease. However, the precise neuropathological changes that occur in brain in response to amyloid deposition are largely unknown. To study the molecular mechanism(s) responsible for Aß-mediated neuropathology, we performed a gene expression analysis on laser-microdissected brain tissue of Tg2576 mice compared to their littermate controls.
Project description:This study has investigated several parameters to obtain increased detection of the amyloid plaque intact protein profile, including a comparison of commonly used MALDI matrices, acid based reduction of signal suppression as well as the combination of strong acid based protein aggregate extraction from laser microdissection plaques to increase detection of proteoforms. Female APPPS1-21 transgenic mice were analyzed by MALDI Imaging with different matrices on a Ultraflextreme MALDI TOF/TOF instrument followed by data analysis in SCiLS Lab software. A combination of formic acid treatment of laser capture microdissected plaques was further utilized to expand the analysis and validation of amyloid plaques.
Project description:Extracellular senile plaques of amyloid beta (Abeta) are a pathological hallmark in brain of patients with Alzheimer`s Disease (AD). Abeta is generated by the amyloidogenic processing of the amyloid precursor protein (APP). Concomitant to Abeta load, AD brain is characterized by an increase in protein level and activity of the angiotensin-converting enzyme (ACE). ACE inhibitors are a widely used class of drugs with established benefits for patients with cardiovascular disease. However, the role of ACE and ACE inhibition in the development of Abeta plaques and the process of AD-related neurodegeneration is not clear since ACE was reported to degrade Abeta. To investigate the effect of ACE inhibition on AD-related pathomechanisms, we used Tg2576 mice with neuron-specific expression of APPSwe as AD model. From 12 months of age, substantial Abeta plaque load accumulates in the hippocampus of Tg2576 mice as a brain region, which is highly vulnerable to AD-related neurodegeneration. The effect of central ACE inhibition was studied by treatment of 12 month-old Tg2576 mice for six months with the brain penetrating ACE inhibitor captopril. At an age of 18 months, hippocampal gene expression profiling was performed of captopril-treated Tg2576 mice relative to untreated 18 month-old Tg2576 controls with high Abeta plaque load. As an additional control, we used 12 month-old Tg2576 mice with low Abeta plaque load. Whole genome microarray gene expression profiling revealed gene expression changes induced by the brain-penetrating ACE inhibitor captopril, which could reflect the neuro-regenerative potential of central ACE inhibition. Microarray gene expression profiling was performed of hippocampi isolated from aged, 18 month-old Tg2576 (APPSwe-transgenic) AD mice with high Abeta plaque load relative to age-matched Tg2576 mice, which were treated for 6 months with the centrally active ACE inhibitor captopril. Another study group consisted of 12 month-old Tg2576 mice with low Abeta plaque load. In total, three study groups were analyzed, i.e. (i) 18 month-old untreated Tg2576 mice with high Abeta plaque load, (ii) age-matched Tg2576 mice treated for 6 months with the brain-penetrating ACE inhibitor captopril (20 mg/kg body weight/day in drinking water), and (iii) untreated 12 month-old Tg2576 mice with low Abeta plaque load reflecting the time point when captopril treatment was initiated. Two biological replicates were made of each group, and total hippocampal RNA of four mice was pooled for one gene chip.
Project description:Amyloid-M-CM-^_ (AM-CM-^_) plaques are pathological hallmarks of Alzheimer disease. However, the precise neuropathological changes that occur in brain in response to amyloid deposition are largely unknown. To study the molecular mechanism(s) responsible for AM-CM-^_-mediated neuropathology, we performed a gene expression analysis on laser-microdissected brain tissue of Tg2576 mice compared to their littermate controls. 4 samples; 2 biological replicates of each condition = 2 transgenic versus 2 non-transgenic mice; double amplification of total RNA; only Cy3; no dye-swaps
Project description:Olfaction is often deregulated in Alzheimer's disease (AD) patients, being also impaired in transgenic Tg2576 AD mouse model, which overexpress the Swedish mutated form of human amyloid precursor protein (APP). However, little is known about the molecular mechanisms that accompany the neurodegeneration of olfactory structures in Tg2576 mice. For that, we have applied proteome- and transcriptome-wide approaches to probe molecular disturbances in the olfactory bulb (OB) dissected from Tg2576 mice (2, and 6 months of age) respect to age-matched wild-type (WT) littermates.
Project description:Extracellular senile plaques of amyloid beta (Abeta) are a pathological hallmark in brain of patients with Alzheimer`s Disease (AD). Abeta is generated by the amyloidogenic processing of the amyloid precursor protein (APP). Concomitant to Abeta load, AD brain is characterized by an increase in protein level and activity of the angiotensin-converting enzyme (ACE). ACE inhibitors are a widely used class of drugs with established benefits for patients with cardiovascular disease. However, the role of ACE and ACE inhibition in the development of Abeta plaques and the process of AD-related neurodegeneration is not clear since ACE was reported to degrade Abeta. To investigate the effect of ACE inhibition on AD-related pathomechanisms, we used Tg2576 mice with neuron-specific expression of APPSwe as AD model. From 12 months of age, substantial Abeta plaque load accumulates in the hippocampus of Tg2576 mice as a brain region, which is highly vulnerable to AD-related neurodegeneration. The effect of central ACE inhibition was studied by treatment of 12 month-old Tg2576 mice for six months with the brain penetrating ACE inhibitor captopril. At an age of 18 months, hippocampal gene expression profiling was performed of captopril-treated Tg2576 mice relative to untreated 18 month-old Tg2576 controls with high Abeta plaque load. As an additional control, we used 12 month-old Tg2576 mice with low Abeta plaque load. Whole genome microarray gene expression profiling revealed gene expression changes induced by the brain-penetrating ACE inhibitor captopril, which could reflect the neuro-regenerative potential of central ACE inhibition.
Project description:The e4 allele of the apolipoprotein E (APOE) gene is the strongest genetic risk factor for late-onset Alzheimer's disease and has been shown to increase amyloid pathology relative to the presence of the e2 and e3 alleles. In the brain, apoE is primarily produced by astrocytes and under pathological conditions also by microglia. The cell-type-specific role of apoE in amyloid pathology, especially after amyloid plaque deposition, has not been fully elucidated. We generated APPPS1-21/Aldh1l1-Cre/ERT2/apoE4flox/flox and APPPS1-21/apoE4flox/flox mice. At 3.8-months-of-age, during the phase of rapid plaque growth, we administered tamoxifen to reduce astrocytic APOE4 and assessed mice at 6-months-of-age. One day before tamoxifen treatment, mice were injected with methoxy-X04, a blood-brain-barrier permeant fluorescent marker that labeled the pre-existing fibrillar amyloid plaques. By using this strategy, we were able to characterize pre-existing plaques prior to the loss of astrocytic APOE4 and to also analyze newly-formed amyloid plaques after the loss of astrocytic APOE4. Interestingly, astrocytic APOE4 deletion strongly reduced pre-existing plaques. It also prevented new plaque formation and decreased glial reactivity. Importantly, the removal of astrocytic APOE4 resulted in enhanced microglial and astrocytic phagocytic ability, which may contribute to the reduction of the amyloid pathology.
Project description:It is well-established that women are disproportionately affected by Alzheimer’s disease (AD). The mechanisms underlying this sex-specific disparity are not fully understood, but several factors that are often associated-including interactions of sex hormones, genetic factors, and the gut microbiome-likely contribute to the disease's etiology. Here, we have examined the role of sex hormones and the gut microbiome in mediating A amyloidosis and neuroinflammation in APPPS1-21 mice. We report that postnatal gut microbiome perturbation in female APPPS1-21 mice leads to an elevation in levels of circulating estradiol. Early stage ovariectomy (OVX) leads to a reduction of plasma estradiol that is correlated with a significant alteration of gut microbiome composition and reduction in A pathology. On the other hand, supplementation of OVX-treated animals with estradiol restores A burden and influences gut microbiome composition. The reduction of A pathology with OVX is paralleled by diminished levels of plaque-associated MGnD-type microglia while estradiol supplementation of OVX-treated animals leads to a restoration of activated microglia around plaques. In summary, our investigation elucidates the complex interplay between sex-specific hormonal modulations, gut microbiome dynamics, metabolic perturbations, and microglial functionality in the pathogenesis of Alzheimer's disease.