Daily Sepsis Research Analysis

Carbapenemase-producing Enterobacterales (CPE) present limited therapeutic options. Optimal treatment requires identifying the carbapenemase type, often requiring confirmatory testing beyond routine susceptibility results. We develop MALCA, a machine-learning classifier that uses routine disc diffusion antibiogram results to directly detect CPE and identify the carbapenemase type. From 11,992 clinical isolates, we build a stepwise random-forest pipeline and derive two classifiers based on panels of 22 or 8 antibiotics (MALCA-22 and MALCA-8). In an external validation study involving 8514 isolates, both MALCA classifiers achieved sensitivity and specificity >96% for CPE detection, outperforming European and French algorithms developed for CPE screening. For the most prevalent carbapenemases, MALCA achieve sensitivities exceeding 97% and specificities above 98%, particularly for OXA-48-like, NDM, and KPC producers. MALCA is a rapid, and inexpensive diagnostic tool that uses solid antibiogram data to detect and type CPE, enabling earlier targeted therapy and diagnostic guidance without additional reagents or human resources.

BACKGROUND: Neutrophil extracellular traps (NETs) can mediate sepsis-induced lung injury, but the upstream regulatory mechanisms remain unclear. IL-33 is involved in neutrophil activation and may serve as an upstream regulator of NET formation. Therefore, this study aims to elucidate the molecular mechanism by which the IL-33/ST2 axis regulates NET formation to mediate sepsis-induced lung injury. METHODS: A mouse model of sepsis-induced lung injury was established using the CLP method to assess lung damage and NETs formation. The destructive effect of NETs on the endothelial barrier was examined through DNase I intervention and HUVECs cell experiments. IL-33 or ST2 gene knockout mice were used to investigate the role of the IL-33/ST2 axis in sepsis-induced lung injury and its regulatory effect on NETs formation. Differentially expressed genes were identified via transcriptome sequencing of mouse neutrophils, and the downstream molecular mechanism of IL-33-induced NETs formation was explored by silencing or overexpressing REDD1 in dHL-60 cells. RESULTS: In septic mice, neutrophil infiltration and elevated levels of NETs were observed in lung tissue, accompanied by pulmonary edema and increased vascular permeability. These injuries were reversed by DNase I intervention. The IL-33/ST2 signaling axis was activated in septic mice, and knockout of either the IL-33 or ST2 gene alleviated lung injury, reduced endothelial barrier disruption, and inhibited NETs formation. In vitro experiments and transcriptome sequencing results demonstrated that IL-33 induces NETs formation in neutrophils through the ST2 receptor, and the ATF4/REDD1 signaling pathway is the key downstream mechanism by which IL-33 promotes NETs formation. CONCLUSION: This study demonstrates that IL-33/ST2 signaling leads to activation of the PERK/eIF2α/ATF4 pathway in neutrophils, upregulates REDD1 to induce NETosis triggered by oxidative stress, and thereby disrupts the pulmonary vascular endothelial barrier, exacerbating sepsis-induced lung injury.

Ferroptosis has been linked to impaired macrophage function and acute lung injury (ALI), a condition associated with high mortality. Nevertheless, the regulatory mechanisms underlying ferroptosis remain to be fully elucidated. In pro-inflammatory macrophages, glycolysis is preferentially upregulated, with pyruvate kinase M2 (PKM2) acting as a key regulatory enzyme. Here, we elucidate a distinct functional role of ferroptosis in this context. We identified CARM1, an arginine methyltransferase, as a crucial metabolic mediator that promotes ferroptosis by activating PKM2-dependent glycolysis. CARM1 is ubiquitously expressed and hyperactivated in sepsis models, leading to elevated levels of glycolysis-related enzymes, including LDHA and PKM2. Therapeutic intervention with the CARM1 inhibitor TP-064 significantly attenuated inflammatory responses in macrophages and ameliorated ALI in septic models. Furthermore, TP-064 suppressed ferroptosis and PKM2-dependent glycolysis both in vitro and in vivo. Notably, genetic ablation of CARM1 phenocopied the inhibitory effects of TP-064. Pharmacological inhibition of PKM2 by shikonin also effectively suppressed ferroptosis-associated markers and alleviated ALI. Taken together, these findings establish CARM1 as an integrative node that couples metabolic reprogramming with PKM2 activity to regulate ferroptosis. Therefore, pharmacological targeting CARM1 may represent a promising therapeutic strategy for mitigating dysregulated ferroptosis and cytokine storm syndromes driven by hyper-glycolytic states.