USP11 plays a critical role in the onset and progression of acute graft-versus-host disease：Novel target for precision therapeutics

Raffinose-metabolizing bacteria impair radiation-associated hematopoietic recovery via the bile acid/FXR/NF-κB signaling pathway

Radiation-associated hematopoietic recovery (RAHR) is critical for mitigating lethal complications of acute radiation syndrome (ARS), yet therapeutic strategies remain limited. Through integrated multi-omics analysis of a total body irradiation (TBI) mouse model, we identify Bacteroides acidifaciens-dominated gut microbiota as key mediators of RAHR impairment. 16S ribosomal rRNA sequencing revealed TBI-induced dysbiosis characterized by Bacteroidaceae enrichment, while functional metagenomics identified raffinose metabolism as the most significantly perturbed pathway. Notably, raffinose supplementation (10% w/v) recapitulated radiation-induced microbiota shifts and delayed bone marrow recovery. Fecal microbiota transplantation (FMT) revealed a causative role for raffinose-metabolizing microbiota, particularly Bacteroides acidifaciens, in delaying RAHR progression. Mechanistically, B. acidifaciens-mediated bile acid deconjugation activated FXR, subsequently suppressing NF-κB-dependent hematopoietic recovery. Therapeutic FXR inhibition via ursodeoxycholic acid (UDCA) had been shown to be a viable method for rescuing RAHR. Our results delineated a microbiome-bile acid-FXR axis as a master regulator of post-irradiation hematopoiesis. Targeting B. acidifaciens or its metabolic derivatives could represent a translatable strategy to mitigate radiation-induced hematopoietic injury.

Deep insight into cytokine storm: from pathogenesis to treatment

Cytokine storm (CS) is a severe systemic inflammatory syndrome characterized by the excessive activation of immune cells and a significant increase in circulating levels of cytokines. This pathological process is implicated in the development of life-threatening conditions such as fulminant myocarditis (FM), acute respiratory distress syndrome (ARDS), primary or secondary hemophagocytic lymphohistiocytosis (HLH), cytokine release syndrome (CRS) associated with chimeric antigen receptor-modified T (CAR-T) therapy, and grade III to IV acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation. The significant involvement of the JAK-STAT pathway, Toll-like receptors, neutrophil extracellular traps, NLRP3 inflammasome, and other signaling pathways has been recognized in the pathogenesis of CS. Therapies targeting these pathways have been developed or are currently being investigated. While novel drugs have demonstrated promising therapeutic efficacy in mitigating CS, the overall mortality rate of CS resulting from underlying diseases remains high. In the clinical setting, the management of CS typically necessitates a multidisciplinary team strategy encompassing the removal of abnormal inflammatory or immune system activation, the preservation of vital organ function, the treatment of the underlying disease, and the provision of life supportive therapy. This review provides a comprehensive overview of the key signaling pathways and associated cytokines implicated in CS, elucidates the impact of dysregulated immune cell activation, and delineates the resultant organ injury associated with CS. In addition, we offer insights and current literature on the management of CS in cases of FM, ARDS, systemic inflammatory response syndrome, treatment-induced CRS, HLH, and other related conditions.

Usp11 maintained the survival of marginal zone B cells under ionizing radiation by deubiquitinating DLL1 and JAG2

Efficacy of radiation therapy is compromised by hematopoietic and immune impairments, with elusive underlying causes. This study aimed to elucidate Usp11's role in radiation-induced injuries and uncover related mechanisms. Utilized ARS mouse model to observe survival rates of Usp11-/- (KO) mice post-TBI (Total Body Irradiation). Assessed lymphocyte and MZ B (Marginal Zone B) cell rates using histological analysis, single-cell sequencing, immunofluorescence (IF), immunohistochemistry (IHC), and flow cytometry (FCM). Conducted Co-IP and ubiquitination experiments for mechanism elucidation. Quantified IgM and IgG using ELISA and FC. Explored public databases for potential correlation molecules. Our findings indicated that Usp11-/- mice exhibited improved survival rates following TBI, with the spleen playing a pivotal role. HE staining revealed a wider marginal zone in the spleen of Usp11+/+ mice post-irradiation. Single-cell sequencing, IF, IHC, and FCM analyses revealed a higher survival rate of MZ B cells in Usp11-/- mice after irradiation. Furthermore, treatment with the Usp11 inhibitor, mitoxantrone, successfully targeted and inhibited Usp11, thereby alleviating the reduction in MZ B cells in the spleen following total body irradiation. Mechanistically, Usp11 sustained the survival of MZ B cells by regulating the ubiquitination of Notch's ligands, DLL1 and JAG2, thereby promoting immune cell remodeling in the spleen. In conclusion, Usp11 played a crucial role in modulating immune system damage induced by ionizing radiation, primarily through ubiquitination of Notch ligands. This study provides insights into radiation-induced immune injuries and suggests Usp11 as a potential therapeutic target.

DUBs in Alzheimer's disease: mechanisms and therapeutic implications

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by the accumulation of amyloid β protein (Aβ) and the hyper-phosphorylation of the microtubule-associated protein Tau. The ubiquitin-proteasome system (UPS) plays a pivotal role in determining the fate of proteins, and its dysregulation can contribute to the buildup of Aβ and Tau. Deubiquitinating enzymes (DUBs), working in conjunction with activating enzymes (E1), ubiquitin-conjugating enzymes (E2), and ubiquitin ligases (E3), actively maintain the delicate balance of protein homeostasis. DUBs specifically remove ubiquitin tags from proteins marked for degradation, thereby averting their proteasomal breakdown. Several DUBs have demonstrated their capacity to regulate the levels of Aβ and Tau by modulating their degree of ubiquitination, underscoring their potential as therapeutic targets for AD. In this context, we present a comprehensive review of AD-associated DUBs and elucidate their physiological roles. Moreover, we delve into the current advancements in developing inhibitors targeting these DUBs, including the determination of cocrystal structures with their respective targets. Additionally, we assess the therapeutic efficacy of these inhibitors in AD, aiming to establish a theoretical foundation for future AD treatments.

USP11 Exacerbates Radiation-Induced Pneumonitis by Activating Endothelial Cell Inflammatory Response via OTUD5-STING Signaling

PURPOSE

Radiation-induced pneumonitis (RIP) seriously limits the application of radiation therapy in the treatment of thoracic tumors, and its etiology and pathogenesis remain elusive. This study aimed to elucidate the role of ubiquitin-specific peptidase 11 (USP11) in the progression of RIP and the associated underlying mechanisms.

METHODS AND MATERIALS

Changes in cytokines and infiltrated immune cells were detected by enzyme-linked immunosorbent assays and immunohistochemistry after exposure to 20 Gy x-ray with whole-thorax irradiation. The effects of USP11 expression on endothelial cell proliferation and apoptosis were analyzed by costaining of CD31/Ki67 and CD31/caspase-3 in vivo, and the production of cytokines and reactive oxygen species was confirmed by reverse-transcription polymerase chain reaction and flow cytometry in vitro. Comprehensive proteome and ubiquitinome analyses were used for USP11 substrate screening after radiation. Results were verified by Western blotting and coimmunoprecipitation experiments. Recombinant adeno-associated virus lung vectors expressing OTUD5 were used for localized overexpression of OTUD5 in mouse pulmonary tissue, and immunohistochemistry was conducted to analyze cytokine expression.

RESULTS

The progression of RIP was significantly alleviated by reduced expression of proinflammatory cytokines in both Usp11-knockout (Usp11-/-) mice and in mice treated with the USP11 inhibitor mitoxantrone. Likewise, the absence of USP11 resulted in decreased permeability of pulmonary vessels and neutrophils and macrophage infiltration. The proliferation rates of endothelial cells were prominently increased in the Usp11-/- lung, whereas apoptosis in Usp11-/- lungs decreased after irradiation compared with that observed in Usp11+/+ lungs. Conversely, USP11 overexpression increased proinflammatory cytokine expression and reactive oxygen species production in endothelial cells after radiation. Comprehensive proteome and ubiquitinome analyses indicated that USP11 overexpression upregulates the expression of several deubiquitinating enzymes, including USP22, USP33, and OTUD5. We demonstrate that USP11 deubiquitinates OTUD5 and implicates the OTUD5-STING signaling pathway in the progression of the inflammatory response in endothelial cells.

CONCLUSIONS

USP11 exacerbates RIP by triggering an inflammatory response in endothelial cells both in vitro and in vivo, and the OTUD5-STING pathway is involved in the USP11-dependent promotion of RIP. This study provides experimental support for the development of precision intervention strategies targeting USP11 to mitigate RIP.