Modified Huanglian Wendan Decoction improves prediabetic renal injury by activating the AMPK/ULK1 pathway to restore autophagy and suppress inflammation

BACKGROUND: Prediabetes represents an intermediate metabolic condition between normal blood glucose and diabetes, characterized by insulin resistance, metabolic dysfunction, and low-grade inflammation, collectively contributing to early renal injury. However, manifestations such as glomerular hyperfiltration, increased urinary protein excretion, and subclinical tubular injury are often overlooked during this stage. Therefore, elucidating the underlying molecular mechanisms and implementing early interventions may significantly attenuate subsequent renal function decline. In this context, although Modified Huanglian Wendan Decoction (MHWD) has demonstrated efficacy in regulating glucose and lipid metabolism, its effects on renal injury during prediabetes have not been fully elucidated. METHODS: UPLC-MS analysis was conducted to characterize the main active compounds of MHWD. Subsequently, a prediabetic rat model was established using a high-fat diet in combination with streptozotocin to explore the effects of MHWD on insulin sensitivity, body weight, blood glucose, and lipid profiles. Transcriptomic and proteomic analyses of the kidneys were subsequently performed to explore MHWD's molecular mechanisms, which were further validated in vivo. In vitro studies in HK-2 cells exposed to high glucose were conducted to explore MHWD mechanisms, with autophagy's role in anti-inflammatory effects assessed using chloroquine and the levels of autophagy-related proteins and inflammatory cytokines determined. Metformin, an AMPK activator, was used as a positive control to assess MHWD's effects on the AMPK/ULK1 pathway, autophagy, and inflammatory responses. The AMPK inhibitor Compound C was subsequently applied to assess whether these protective effects were dependent on the AMPK/ULK1 pathway. RESULTS: UPLC-MS analysis identified 15 principal chemical constituents of MHWD. In prediabetic rats, MHWD treatment alleviated metabolic abnormalities, including hyperglycemia, insulin resistance, dyslipidemia, and weight gain, while attenuating renal injury and systemic as well as renal inflammation. Transcriptomic and proteomic analyses indicated that MHWD exerted its core effects through metabolic regulation, restoration of autophagy, and anti-inflammatory actions. Transmission electron microscopy, immunofluorescence, and Western blot analyses confirmed that MHWD restores renal autophagy and suppresses inflammation via the AMPK/ULK1 pathway. These effects were recapitulated in high-glucose-exposed HK-2 cells and were comparable to those of metformin. Inhibition by chloroquine or Compound C suppressed the protective effects of MHWD, indicating that its renal protective and anti-inflammatory benefits were mediated via AMPK/ULK1-dependent autophagy, thereby mitigating metabolic dysregulation and renal injury in prediabetic states. CONCLUSIONS: MHWD ameliorates metabolic disorders and preserves renal function in prediabetes by restoring autophagic homeostasis, enhancing energy metabolism, and suppressing inflammation via the AMPK/ULK1 pathway, offering a mechanistic basis for early kidney protection and potential clinical application.