Targeting the TLR4/NF-κB/TNF-α/MMP axis with dexamethasone attenuates glycocalyx degradation and restores microcirculatory perfusion in septic kidneys.

Sepsis-induced acute kidney injury (S-AKI) is a life-threatening condition in critically ill patients, primarily driven by microcirculatory dysfunction. However, the precise molecular pathways linking systemic inflammation to microvascular collapse remain poorly defined, hindering targeted therapeutic development. We employed an integrative approach, starting with bulk RNA sequencing of septic murine kidneys to map global transcriptomic alterations. Bioinformatic analyses including GO, KEGG, GSEA, and GSVA were used to identify pivotal pathways. These discoveries were then rigorously validated through in vitro models using human renal glomerular endothelial cells (HRGECs) and in vivo murine models of sepsis. Key assessments included histopathology, transmission electron microscopy, vascular permeability assays, and laser speckle contrast imaging for perfusion. Our transcriptomic landscape analysis pinpointed aberrant extracellular matrix (ECM) remodeling and activation of the TLR4/NF-κB/TNF-α axis as the central pathological features in S-AKI. A protein-protein interaction network centered on MyD88, TLR4, TNF, and NF-κB revealed a coherent signaling module. Functional studies confirmed that this axis promotes the expression of matrix metalloproteinases (MMP-9/MMP-3), leading to degradation of the endothelial glycocalyx (evidenced by increased HS, HA, CS and SDC1) and disruption of tight junctions (ZO-1 downregulation). This cascade was associated with markedly increased microvascular permeability and profound renal hypoperfusion. Crucially, the anti-inflammatory agent dexamethasone(DXM) effectively suppressed this entire TLR4/NF-κB/TNF-α/MMP pathway, thereby attenuating glycocalyx damage, restoring endothelial integrity, and significantly improving renal microcirculatory perfusion. Our study identifies the TLR4/NF-κB/TNF-α/MMP axis as a key pathway associated with septic AKI, potentially bridging innate immune activation and microvascular failure. The potent protective effect of DXM, mediated through this pathway, provides a compelling mechanistic rationale for its potential application in managing sepsis-induced organ dysfunction.