Project description:Evolution of glomerulonephritis (GN) to tubulointerstitial disease is a universal antecedent to the development of chronic kidney disease (CKD). There is also evidence that angiotensin converting enzyme (ACE) inhibition may attenuate the development of CKD in some forms of glomerulonephritis. We tested the role of ACE inhibition in a model of GN in which complement-dependent tubulointerstitial disease develops. GN was induced in C57BL/6 mice with intraperitoneal injections of horse spleen apoferritin (HSA) using lipopolysaccharide (LPS) as an adjuvant. Four groups of six animals were studied: saline-injected control mice treated with captopril or water, and GN mice treated with captopril or water. GN developed in all HSA-treated animals. In those receiving captopril, however, proteinuria (albumin/creatinine ratio) was significantly reduced by captopril treatment. Array screening was used to examined the expression of collagen-related genes and determine if these effects could be mediated by regulation of collagen genes. Six genes were identified for further analysis by quantitative RT-PCR. This model demonstrates that tubulointerstitial disease can be attenuated by ACE inhibition, with clinical, histologic, and gene expression measures. All protocols were approved by the Institutional Animal Care and Use Committee at SUNY Upstate Medical University. We employed four groups of six mice each: saline-injected control mice with and without captopril, and GN with and without captopril. C57BL/6 mice were purchased from The Jackson Laboratories (Bar Harbor, ME). Glomerulonephritis (GN) was induced by intraperitoneal (i.p.) injection of 10 mg of apoferritin from horse spleen (HSA, Sigma, St. Louis, MO) five days per week, with i.p. injection of 100 micrograms lipopolysaccharide (LPS, from Salmonella minnesota; EMD Biosciences, La Jolla, CA), as adjuvant, three times per week. Control animals received equal volumes of 0.15 M NaCl by i.p. injection. Injections were begun when the mice were approximately eight weeks of age and were continued for six weeks. Captopril, at 100 mg/kg/day was given in the drinking water. After 9 weeks, the animals were euthanized and kidneys were removed for RNA purification and analysis.

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.

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