Calcium Oxalate Kidney Stones: Pathogenesis of Obesity-associated Hyperoxaluria

草酸钙肾结石：肥胖相关高草酸尿症的发病机制

• 批准号: 8673535
• 负责人: HATIM A HASSAN
• 金额: $ 34.37万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8673535
• 关键词: Affect; Anions; Apical; Bathing; Body Size; Calcium Oxalate; Calculi; Celiac Disease; Cells; Creatinine; Diet; Dose; Excretory function; GCG gene; GLP-2; Glycolates; Goals; Human; Hyperoxaluria; Hyperphagia; Inbred BALB C Mice; Incidence; Interferons; Interleukin-6; Intestines; Kidney Calculi; Knockout Mice; Leptin; Life; Ligands; Mannitol; Mediating; Messenger RNA; Minor; Modeling; Molecular; Mus; Obesity; Oral; Oxalates; Pathogenesis; Peptides; Permeability; Play; Prevalence; Reporting; Risk; Risk Factors; Role; TNF gene; Testing; Therapeutic; Therapeutic Effect; Tissues; Urine; absorption; base; cost; cytokine; db/db mouse; feeding; improved; in vivo; intestinal epithelium; neutralizing antibody; nonalcoholic steatohepatitis; protein expression; public health relevance; uptake; urinary

DESCRIPTION (provided by applicant): 70-80% of kidney stones (KS) are composed of calcium oxalate, and minor changes in urine oxalate affect the stone risk. Obesity is a risk factor for KS and obese stone formers often have mild hyperoxaluria. A positive correlation between increased body size and elevated urinary oxalate excretion was reported; however, the underlying mechanism(s) remain(s) unknown. Therefore, we initiated studies in the obese ob/ob (ob) mice to define the pathogenesis of the obesity-associated hyperoxaluria (OAH). ob mice were found to have significantly higher urine oxalate (adjusted for creatinine) compared to controls (>2.9-fold), which is not due to overeating using pair-feeding. Significant hyperoxaluria was also seen in the obese db/db mice (> 2.3-fold). We observed significantly higher jejunal (> 46%) and ileal (>30%) 14C-oxalate and 3H-mannitol (a paracellular marker) absorptive fluxes in ob mice compared to controls ex vivo. Importantly, a significantly higher (>35%) urine 13C-oxalate was observed in ob mice compared to controls following an oral gavage with 13C-oxalate. The proinflammatory cytokines (PCs) IFN-? [IFN] and TNF-¿ [TNF], which are elevated in obesity, caused > 3- fold increase in apical to basolateral 14C-oxalate and 3H-mannitol fluxes in human intestinal Caco2-BBE (C2) cells. The PC-induced increased absorptive fluxes were completed blocked by pretreatment with AMP-18 and GLP-2, peptides known to improve intestinal barrier function. Pretreatment of BALB/c mice with TNF before isolating and mounting jejunal segments in Ussing chambers led to > 1.9-fold increase in 14C -oxalate and 3H- mannitol absorptive fluxes, an effect completely blocked by pretreatment with AMP or GLP. IFN, TNF, and IL-6 also significantly inhibited apical 14C-oxalate uptake by C2 cells through mechanisms involving reduced SLC26A6 (A6), an anion exchanger with essential role in intestinal oxalate secretion, mRNA/total protein expression. In addition, ob mice have significantly reduced jejunal A6 mRNA (>65%) and total protein expression. while a small net oxalate secretory flux was observed in control jejunal tissues, a large net absorptive flux was seen in ob tissues, due to significantly reduced secretory flux and an increased absorptive flux . Based on these findings, I will test the hypothesis that PCs play an important role in the OAH, and that anti-TNF, anti-IFN, and/or anti-IL-6 will normalize and/or ameliorate the observed hyperoxaluria. The following specific aims will be pursued: 1a. Evaluate the therapeutic effects of anti-TNF, anti-IFN, and anti-IL-6 on the observed hyperoxaluria.1b. Evaluate the effects of crossing the ob mice with the TNF, IFN, and/or IL-6 null mice on the observed hyperoxaluria to confirm their roles in the OAH. 2a. Assess small and large intestinal paracellular permeability in vivo in ob mice and their controls. 2b. Examine the therapeutic effects of AMP and GLP on the observed hyperoxaluria. 2c. Elucidate the in vivo mechanisms by which AMP, GLP, anti-TNF, anti- IFN, and/or anti-IL-6 normalize and/or ameliorate the observed hyperoxaluria. 3. Evaluate the effects of crossing the ob mice with the A6 null mice on the observed hyperoxaluria to confirm the role of A6 in the OAH.

描述（申请人提供）：70-80% 的肾结石 (KS) 由草酸钙组成，尿液草酸的微小变化会影响结石风险。肥胖是一个危险因素。 据报道，KS 和肥胖结石形成者通常患有轻度高草酸尿症，但其潜在机制仍不清楚。 ob (ob) 小鼠用于定义肥胖相关高草酸尿症 (OAH) 的发病机制，发现与对照组相比，ob 小鼠的尿液草酸盐（针对肌酐进行调整）显着升高。 （>2.9 倍），这不是由于配对喂养的暴饮暴食所致，在肥胖 db/db 小鼠中也发现了显着的高草酸尿症（> 2.3 倍），我们观察到空肠（> 46%）和回肠（> 46%）显着升高。与体外对照相比，ob 小鼠中的 14C-草酸和 3H-甘露醇（一种旁细胞标记物）吸收通量 >30%。重要的是，与对照组相比，口服 13C-草酸盐后，ob 小鼠的尿液 13C-草酸盐显着升高（>35%）。 [TNF]在肥胖中升高，导致人肠Caco2-BBE (C2)细胞中顶端至基底外侧的14C-草酸和3H-甘露醇通量增加>3倍。PC诱导的吸收通量的增加被完全阻断。用 AMP-18 和 GLP-2 进行预处理，这些肽已知可改善肠道屏障功能 在分离和安装之前用 TNF 对 BALB/c 小鼠进行预处理。 Ussing 室中的空肠段导致 14C-草酸和 3H-甘露醇吸收通量增加 > 1.9 倍，该效应被 AMP 或 GLP 预处理完全阻断，并且还显着抑制顶端 14C-草酸摄取。 C2 细胞通过涉及减少 SLC26A6 (A6) 的机制，SLC26A6 (A6) 是一种在肠道草酸盐中具有重要作用的阴离子交换剂此外，ob 小鼠的空肠 A6 mRNA (>65%) 和总蛋白表达显着降低，而在对照空肠组织中观察到较小的净草酸盐分泌通量，但观察到较大的净吸收通量。在 ob 组织中，由于分泌通量显着减少和吸收通量增加，基于这些发现，我将检验 PC 在 OAH 中发挥重要作用的假设，以及抗 TNF、抗-IFN、和/或抗-IL-6将使观察到的高草酸尿正常化和/或改善。将追求以下具体目标： 1a.评估抗-TNF、抗-IFN和抗-IL-的治疗效果。 6 对观察到的高草酸尿症。1b. 评估将 ob 小鼠与 TNF、IFN 和/或 IL-6 缺失小鼠杂交对观察到的高草酸尿症的影响，以确认它们在 OAH 中的作用。 2a. 评估 ob 小鼠及其对照的小肠和大肠旁细胞通透性 2b. 检查 AMP 和 GLP 对观察到的高草酸尿症的治疗作用。抗-IFN和/或抗-IL-6使观察到的高草酸尿正常化和/或改善。 3.评估将ob小鼠与b小鼠杂交的效果。对A6缺失小鼠观察到高草酸尿症，以证实A6在OAH中的作用。