HMGB1-mediated formation of IL-33–abundant NETs drives lung-to-kidney injury in severe pneumonia–associated acute kidney injury
Mengqing Ma, Hao Zhang, Weijuan Deng, Xia Du, Mengxing Chen, Dawei Chen, Binbin Pan, Zhaowei Wang, Ting Chen, Caimei Chen, Xin Wan, Changchun Cao
Mengqing Ma, Hao Zhang, Weijuan Deng, Xia Du, Mengxing Chen, Dawei Chen, Binbin Pan, Zhaowei Wang, Ting Chen, Caimei Chen, Xin Wan, Changchun Cao
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Research Article Inflammation Nephrology Pulmonology

HMGB1-mediated formation of IL-33–abundant NETs drives lung-to-kidney injury in severe pneumonia–associated acute kidney injury

Abstract

Acute kidney injury (AKI) is a common and fatal complication of severe pneumonia, yet the mechanisms linking pulmonary inflammation to remote kidney injury remain poorly understood. Multicenter cohort data (n = 300) revealed that the incidence of severe pneumonia–associated AKI (SP-AKI) was 53.6%, with a mortality rate of 24.2%. SP-AKI was associated with elevated circulating levels of HMGB1, NETs, and IL-33. Murine experiments demonstrated that alveolar HMGB1 triggers the formation of IL-33–enriched NETs, which migrate to the kidney and activate tubular ST2/NF-κB signaling, driving inflammation and apoptosis. Genetic knockout of IL-33, ST2, or the NET-forming key enzyme PAD4, as well as pharmacological inhibition of HMGB1, IL-33, or NETs, all attenuated lung and kidney injury. Exogenous HMGB1 amplified NET-mediated IL-33 release, establishing a self-sustaining HMGB1/NET/IL-33 feed-forward loop. PAD4 deficiency completely blocked NET generation and disrupted HMGB1/IL-33 signaling. This study identified and validated a damage-associated molecular pattern–driven (DAMP-driven) HMGB1/NET/IL-33 signaling axis that mediates remote kidney injury in SP-AKI, redefining NETs from local effectors to cross-organ pathogenic carriers, thereby providing potential DAMP-targeted therapeutic avenues for SP-AKI.

Authors

Mengqing Ma, Hao Zhang, Weijuan Deng, Xia Du, Mengxing Chen, Dawei Chen, Binbin Pan, Zhaowei Wang, Ting Chen, Caimei Chen, Xin Wan, Changchun Cao

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Figure 1

Elevated serum HMGB1, NET, and IL-33 levels are associated with SP-AKI in patients.

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Elevated serum HMGB1, NET, and IL-33 levels are associated with SP-AKI i...
(A) Schematic of serum proteomic analysis comparing patients with SP–non-AKI (n = 10) and SP-AKI (n = 10), showing upregulated and downregulated serum proteins. (B) Heatmap of differentially expressed proteins between SP–non-AKI and SP-AKI, with hierarchical clustering. Red, upregulated; blue, downregulated. (C) Public single-cell transcriptomic analysis of human lungs with bacterial and viral infections reveals major pulmonary cell populations (GSE268542). (D) Dot plot showing high-mobility group box 1 (HMGB1) expression across lung cell types in uninfected versus infected conditions. (E) Gene set enrichment analysis demonstrating significant enrichment of the neutrophil extracellular trap (NET) formation pathway. Normalized enrichment score (NES) and false discovery rate (FDR) are shown. (F) Violin plot showing IL-33 expression in neutrophils under uninfected and infected conditions. (G) Schematic diagram. Blood samples were collected upon admission from patients with SP-non-AKI (n = 139) and SP-AKI (n = 161), including ELISA measurement of serum HMGB1, IL-33, neutrophil gelatinase-associated lipocalin (NGAL), and NET-DNA complex levels, as well as flow cytometric analysis. (H) Serum concentrations of HMGB1 in patients without AKI and in patients with AKI stages 1–3 (total n = 300). (I–M) Serum levels of IL-33 (I), NGAL (J), citrullinated histone H3–DNA (CitH3-DNA) complexes (K), myeloperoxidase-DNA (MPO-DNA) complexes (L), and neutrophil elastase–DNA (NE-DNA) complexes (M). (N) Correlation matrix showing associations among circulating biomarkers, including IL-33, HMGB1, NGAL, NET-DNA markers, and clinical indices. (O and P) Representative flow cytometry plots and quantitative analysis of IL-33+ neutrophils (CD66b+IL-33+) in peripheral blood from healthy controls, SP–non-AKI patients, and SP-AKI patients (n = 5). Data are presented as mean ± SD. P values were calculated by 1-way ANOVA with post hoc Holm-Šídák test. ****P < 0.0001.