Table 13_Integrated causal inference, kidney transcriptomics, and experimental validation identify ChREBP (MLXIPL) as a driver of maladaptive metabolic remodeling in diabetic kidney disease.docx

BackgroundDiabetic kidney disease (DKD) remains a leading cause of end-stage renal disease despite advances in glucose-, blood pressure-, and albuminuria-lowering therapies. The glucose-responsive transcription factor carbohydrate response element-binding protein (ChREBP; encoded by MLXIPL) regulates glycolytic–lipogenic programs, yet its causal contribution to renal injury is challenging to disentangle in advanced DKD, where bulk kidney transcriptomes reflect tissue remodeling and cellular compositional shifts.
MethodsWe integrated two-sample Mendelian randomization (MR), kidney transcriptomic stratification, network analyses, and experimental validation. MR used blood cis-eQTL instruments for MLXIPL to estimate causal effects on type 2 diabetes (T2D) and urinary albumin-to-creatinine ratio (UACR), including a non-diabetic UACR stratum. In kidney transcriptomics (GSE30529), we evaluated remodeling-related confounding and applied within-DKD, median-based MLXIPL-high/low stratification for GSEA/GSVA and functional/network inference. Key observations were validated in db/db mice and primary proximal tubular epithelial cells (PTECs) exposed to high glucose with matched osmotic control.
ResultsGenetically predicted higher MLXIPL expression was associated with increased T2D risk across multiple phenotype definitions and with higher UACR, including replication in non-diabetic individuals. Within DKD, MLXIPL heterogeneity tracked metabolic programs by GSEA and divergent pathway activity by GSVA, while signatures related to profibrotic and proliferative remodeling were concomitantly enriched in the low-MLXIPL subgroup. Network analyses positioned MLXIPL/ChREBP within a dense metabolic interaction and regulatory landscape. Experimentally, ChREBP and Mlxipl were increased in db/db kidneys and induced by high glucose in PTECs, accompanied by coordinated upregulation of lipogenic targets (Acly, Acaca, Fasn, Srebf1) and an inverse relationship with Ppargc1b.
ConclusionsIntegrating genetic inference, confounding-aware kidney transcriptomics, network biology, and experimental validation, our study supports MLXIPL/ChREBP as a pathogenic nutrient-sensing node linking diabetes susceptibility to renal injury and maladaptive metabolic remodeling in DKD, providing a mechanistic rationale for targeting this axis to mitigate residual renal risk.

背景：尽管在降糖、降压及降低蛋白尿治疗方面已取得进展，糖尿病肾病(Diabetic kidney disease, DKD)仍是终末期肾病(end-stage renal disease)的首要病因。葡萄糖反应性转录因子碳水化合物反应元件结合蛋白(Carbohydrate Response Element-Binding Protein, ChREBP，由MLXIPL编码)可调控糖酵解-脂肪生成程序，但在晚期DKD中，其对肾损伤的因果贡献难以厘清——此时肾脏整体转录组可反映组织重塑与细胞组成的动态变化。
方法：本研究整合了双样本孟德尔随机化(Two-sample Mendelian Randomization, MR)、肾脏转录组分层分析、网络分析与实验验证。MR以血液中MLXIPL的顺式eQTL(cis-eQTL)作为工具变量，评估其对2型糖尿病(Type 2 Diabetes, T2D)及尿白蛋白肌酐比(Urinary Albumin-to-Creatinine Ratio, UACR)的因果效应，其中包含非糖尿病个体的UACR亚组分析。在肾脏转录组数据集(GSE30529)中，我们评估了与重塑相关的混杂因素，并基于DKD队列内的MLXIPL表达中位数进行高低分组，以此开展基因集富集分析(Gene Set Enrichment Analysis, GSEA)、基因集变异分析(Gene Set Variation Analysis, GSVA)以及功能与网络推断。关键研究结果在db/db小鼠及暴露于高糖（并设置匹配渗透压对照）的原代近端肾小管上皮细胞(Primary Proximal Tubular Epithelial Cells, PTECs)中得到验证。
结果：在多种表型定义下，遗传预测的MLXIPL高表达与T2D风险升高及UACR升高相关，该结果在非糖尿病个体中得到重复验证。在DKD队列中，MLXIPL表达异质性通过GSEA追踪到代谢程序特征，通过GSVA揭示了通路活性的差异；与此同时，促纤维化与增殖性重塑相关特征在MLXIPL低表达亚组中显著富集。网络分析将MLXIPL/ChREBP定位至一个紧密的代谢互作与调控网络中。实验层面，db/db小鼠肾脏中的ChREBP与Mlxipl表达水平升高，PTECs经高糖处理后二者表达亦被诱导，同时伴随脂肪生成靶点基因（Acly、Acaca、Fasn、Srebf1）的协同上调，且与Ppargc1b呈负相关关系。
结论：本研究整合遗传推断、考虑混杂因素的肾脏转录组学、网络生物学与实验验证，证实MLXIPL/ChREBP可作为致病的营养感知节点，将糖尿病易感性与DKD中的肾损伤及适应性不良代谢重塑联系起来，为靶向该通路以减轻残余肾脏风险提供了机制依据。