Timing of Diet and Kidney Pathophysiology in Diet-Induced Obesity

总结 肥胖症在肾功能障碍升级、体液稳态破坏、肾功能衰竭、糖尿病、糖尿病和糖尿病等方面尤其严重。 损伤我们的饮食诱导的肥胖（DIO）小鼠模型（20周，随意45%高脂饮食，HFD） 周期，肾线粒体代谢受损，肾髓质氧化应激和 活性氧（ROS），以及增加骨髓间质纤维化相比，小鼠正常 饮食.值得注意的是，通过时间限制食物摄入（TRF）恢复喂养-禁食周期，而不改变总 DIO最后2周的热量摄入，重建全身昼夜能量代谢，正常化 氧化剂和肾损伤标志物的排泄，以及消除肾间质纤维化和T细胞浸润。 这些显著的发现清楚地表明，喂养-禁食周期对肥胖患者的肾脏健康至关重要。的 拟议研究的目标是明确进食-禁食周期的时间安排如何影响肾脏 线粒体呼吸、炎症和纤维化。我们的核心假设是定时进食- 禁食通过恢复肾线粒体功能和减少T细胞减少来改善DIO驱动的肾纤维化 激活并迁移至肾脏。先前的研究表明，时钟基因Bmal 1调节线粒体 功能，但这是否是DIO诱导的肾脏代谢功能障碍的关键是未知的。我们的新 数据显示，Bmal 1基因敲除小鼠肾髓质线粒体呼吸存在显著的时间差异 与野生型同窝仔相比。在我们的DIO模型中，我们观察到全身能量的昼夜节律 代谢丧失，但由扶轮基金会恢复。我们还观察到DIO导致昼夜节律的相移， 肾脏中的分子钟我们认为，TRF在肥胖症中的作用机制， 肾脏线粒体代谢是通过重建时钟活性和抑制ROS产生。 此外，TRF消除了肥胖患者肾间质纤维化和肾血管相关的T细胞浸润。 这表明定时喂食禁食通过减少肾脏T细胞炎症来促进肾脏健康。我们 新的数据发现，内皮源性ET-1特异性介导肾脏促炎性CD 4 +T细胞 activation.我们发现肠道促炎T细胞活化和细胞因子产生是ETA依赖性的， 肠道中的CD 4 +T细胞迁移到外周组织。因此，我们进一步提出，TRF减轻了DIO驱动的 T细胞钟恢复肾内皮源性ET-1昼夜节律治疗肾间质纤维化 活性和ETA依赖性T细胞活化以及从肠道向肾脏的迁移。研究将涉及两个 具体目的：首先，检验TRF通过Bmal 1介导的肾纤维化减少DIO中的肾纤维化的假设。 线粒体功能的恢复和细胞源性ROS的减少。第二，检验假设 TRF通过恢复肾脏中生理性内皮源性ET-1来减轻DIO驱动的肾纤维化 T细胞活化。

SUMMARY Obesity is particularly severe in terms of escalating kidney dysfunction, disrupted body fluid homeostasis, kidney injury. Our diet-induced obesity (DIO) mouse model (20-wk, ad lib 45% high fat diet, HFD) dampened feeding cycles, impaired kidney mitochondrial metabolism, amplified kidney medullary oxidative stress and excretion of reactive oxygen species (ROS), as well as increased medullary interstitial fibrosis compared to mice on a normal diet. Remarkably, restoring feeding-fasting cycles through time-restricted food intake (TRF), without altering total caloric intake during the final 2 weeks of DIO, re-established whole body diurnal energy metabolism, normalized excretion of oxidants and renal injury markers, as well as abolished renal interstitial fibrosis and T cell infiltration. These remarkable findings clearly indicate that feeding-fasting cycles are critical for kidney health in obesity. The goal of the proposed studies is to determine specifically how timing of feeding-fasting cycles impacts kidney mitochondrial respiration, inflammation and fibrosis in obesity. Our central hypothesis states that timed feeding- fasting ameliorates DIO-driven kidney fibrosis by reinstating kidney mitochondrial function and reducing T cell activation and migration to the kidney. Prior studies suggest that the clock gene, Bmal1, regulates mitochondrial function, but whether this is critical for DIO-induced metabolic dysfunction in the kidney is unknown. Our new data reveal significant, time-of-day differences in mitochondrial respiration in renal medulla of Bmal1 knockouts compared to wildtype littermates. In our model of DIO, we observed that circadian rhythms in whole body energy metabolism are lost but restored by TRF. We also observed that DIO causes a phase shift in the circadian molecular clock in the kidney. We posit that the mechanisms responsible for the TRF effects in obesity to restore kidney mitochondrial metabolism is via re-establishing clock activity and suppressing ROS production. Furthermore, TRF abolishes kidney interstitial fibrosis and kidney vasa recta-associated T cell infiltration in obese mice suggesting that timed feeding-fasting promotes kidney health by reducing kidney T cell inflammation. Our new data found that endothelium-derived ET-1 specifically mediates kidney pro-inflammatory CD4+T cell activation. We show that gut pro-inflammatory T cell activation and cytokine production is ETA dependent and that CD4+T cells in the gut migrate to peripheral tissues. Thus, we further propose that TRF mitigates DIO-driven kidney medullary fibrosis by reinstating diurnal rhythms of kidney endothelium-derived ET-1 with T cell clock activity and ETA dependent T cell activation and migration from the gut to the kidney. Studies will address two specific aims: First, to test the hypothesis that TRF reduces kidney fibrosis in DIO through Bmal1 mediated restoration of mitochondrial function and reduced mitochondrial-derived ROS. Second, to test the hypothesis that TRF mitigates DIO-driven kidney fibrosis by reinstating physiological endothelium-derived ET-1 in the kidney with T cell activation.