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 2

HMGB1 upregulation promotes neutrophil recruitment and IL-33–enriched NET formation in SP-AKI mouse lungs.

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HMGB1 upregulation promotes neutrophil recruitment and IL-33–enriched NE...
(A) Representative immunohistochemical staining of HMGB1 and Ly6G in lung sections from sham and SP-AKI model mice. Negative staining controls are shown. Scale bars: 50 μm. (B and C) Quantification of HMGB1+ area and Ly6G+ neutrophils in lung sections from sham and SP-AKI model mice. (D) Representative immunofluorescence images showing Ly6G (green), MPO (pink), and DAPI (blue) staining in lung sections from sham and model mice. Scale bars: 25 μm. (E) Gene set enrichment analysis of RNA-seq data showing enrichment of the NET formation pathway in lung tissues from SP-AKI mice versus sham controls. (F and G) Western blots showing the expression of MPO, CitH3, HMGB1, and IL-33 in lung tissues. (H–K) Semiquantitative analysis of MPO (H), CitH3 (I), HMGB1(J), and IL-33 (K) protein levels. (L–Q) ELISA quantification of HMGB1, MPO-DNA complexes, and CitH3-DNA complexes in serum and BALF from sham and SP-AKI model mice. (R and S) Relative mRNA expression levels of HMGB1 (R) and IL-33 (S) in lung tissues. (T) Representative immunofluorescence images showing PAD4, Ly6G, and IL-33 expression in lung sections from sham and model mice, with merged and enlarged views. Scale bars: 50 μm. Enlarged panels show 5-fold magnification of boxed regions. Data are presented as mean ± SD. n = 5–7 per group. P values were calculated by 2-tailed Student’s t test. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.