Myofibroblasts are the principal effector cells of renal interstitial fibrosis (RIF), but the relative contribution of proposed cellular sources remains disputed. Macrophage-to-myofibroblast transition (MMT) has been inferred from marker co-expression, single-recombinase lineage tracing, and functional perturbation, whereas high-specificity dual-recombinase tracing in unilateral ureteral obstruction identified resident fibroblasts as the predominant myofibroblast source and detected no appreciable macrophage contribution. We therefore distinguish three evidentiary categories: lineage-confirmed MMT, MMT-like macrophage remodeling, and broader profibrotic macrophage activation. We compare co-expression phenotyping, lineage-tracing systems, single-cell and spatial omics, and in vitro induction; organize candidate mechanisms into a causal hierarchy centered on TGF-β1/Smad3-Src-Pou4f1; and assess disease context and therapeutic implications. Current evidence does not support MMT as a universal or quantitatively dominant source. Whether a small MMT-like population exerts disproportionate local effects remains a testable hypothesis, not an established conclusion. We close with falsifiable experiments designed to define where, when, and by which criteria macrophage-derived fibrogenic states can be demonstrated in RIF.
Pulsed low-dose-rate radiotherapy (PLDR) is a promising reirradiation strategy for refractory solid tumors because of its potential to reduce normal tissue toxicity; however, its immunomodulatory mechanisms remain poorly understood. In this study, we retrospectively analyzed clinical outcomes and treatment-related adverse events in 16 patients with refractory solid tumors treated with PLDR. Using MC38 tumor-bearing mice, we compared PLDR and conventional radiotherapy (cRT) under biologically equivalent dose conditions and performed single-cell RNA sequencing to characterize treatment-associated remodeling of the tumor immune microenvironment (TIM). Multiplex immunofluorescence staining and spatial analysis were further conducted in an independent cohort of 114 patients with rectal cancer to evaluate the clinical relevance of identified immune features. PLDR achieved comparable local tumor control to cRT while reducing treatment-related toxicity and improving overall survival (OS) in mouse models. In the combination-treatment setting, single-cell analyses showed that PLDR + immunotherapy with an anti-PD-1 antibody combined with the targeted agent anlotinib (ITT), compared with cRT + ITT, was associated with enrichment of Gzmk⁺ CD8⁺ T cells, reduced Spp1⁺ tumor-associated macrophages (TAMs) abundance, and altered cell–cell communication between these populations. In our independent rectal cancer cohort, the spatial distance between SPP1⁺ TAMs and GZMK⁺ CD8⁺ T cells was independently associated with OS. These findings suggest that the interaction between SPP1⁺ TAMs and GZMK⁺ CD8⁺ T cells may be closely associated with PLDR-related TIM remodeling and may also serve as a potential prognostic biomarker in rectal cancer.
Small ubiquitin-like modifier (SUMO) conjugation (SUMOylation) and deconjugation (deSUMOylation) regulate protein stability, subcellular localisation, and protein interactions, but their contributions to organ injury in sepsis remain incompletely understood. This review assesses SUMO-related evidence according to disease relevance and mechanistic causality, distinguishing findings from patient samples and infection-based sepsis models from those obtained in endotoxemia, acute injury models, and other nonsepsis systems. Available evidence implicates SUMOylation and deSUMOylation in inflammatory signalling, immunometabolic adaptation, barrier homeostasis, mitochondrial quality control, and regulated cell death, suggesting potential links between immune dysfunction, cellular stress, and organ injury. Their effects depend on the SUMO paralogue, regulatory enzyme, substrate, modification site, cell type, tissue compartment, and infection context. Changes in bulk SUMO1 or SUMO2/3 conjugation therefore cannot be interpreted as uniformly protective or pathogenic. Direct human evidence and causal evidence resolved by cell type in infection-based models remain limited, and many proposed mechanisms lack endogenous site mapping or rescue validation. Broad pharmacological inhibition of the SUMO pathway has produced discordant results across experimental models, and the clinical safety and efficacy of interventions targeting SUMO in sepsis remain unestablished. Future studies should establish causal relationships between SUMO enzymes, substrates, and modification sites in defined cell types; develop reproducible pharmacodynamic biomarkers; and evaluate targeted interventions in clinically relevant models after infection is established.
To investigate the therapeutic mechanism of Gegen Qinlian capsule (GGQL) in diabetic cardiomyopathy (DbCM) and identify a key candidate bioactive constituent responsible for cardioprotection. A murine DbCM model was established by high-fat diet feeding combined with streptozotocin injection. GGQL was administered at three doses for 8 weeks. Cardiac injury was evaluated by echocardiography, histology, and serum biomarkers. Untargeted metabolomics and RNA sequencing were performed to characterize metabolic and transcriptional reprogramming. Network pharmacology, molecular docking, and cellular thermal shift assay (CETSA) were integrated to identify the principal active compound and its molecular target. Ferroptosis was assessed through GPX4/SLC7A11 protein expression, oxidative stress markers (MDA, ROS, Fe2+), and antioxidant capacity. Mechanistic validation employed PPARG lentiviral knockdown in H9C2 cardiomyocytes and pharmacological PPARγ antagonism (GW9662) in vivo. GGQL dose-dependently attenuated cardiomyocyte hypertrophy, myocardial fibrosis, and systolic dysfunction, while suppressing ferroptotic markers and restoring GPX4/SLC7A11 expression. Multi-omics profiling converged on PPAR signaling and fatty acid oxidation as dominant therapeutic axes. Network pharmacology identified PPARγ as the central hub target. Formononetin (FMN) exhibited the highest PPARγ binding affinity (-9.3 kcal/mol), and CETSA confirmed direct intracellular target engagement. PPARG silencing and GW9662 co-administration each abolished FMN-mediated cardioprotection and anti-ferroptotic effects. Mechanistically, FMN activated the PI3K/AKT/mTOR signaling axis downstream of PPARγ, and PI3K inhibition reversed GPX4/SLC7A11 upregulation. FMN is a key candidate bioactive constituent of GGQL that attenuates DbCM by suppressing ferroptosis through a PPARγ-PI3K/AKT/mTOR-GPX4/SLC7A11 signaling cascade, providing a mechanistic basis for GGQL's clinical use in diabetic cardiovascular disease.
Cardiac hypertrophy is a complex physiological or pathological process. N6-methyladenosine (m6A) methylation has been reported to be involved in this process. This study aimed to investigate the effect of ALKBH5 on cardiac hypertrophy and the relevant molecular mechanisms using in vitro experiments. H9C2 cells were treated with phenylephrine (PE) to simulate hypertrophy, which was evaluated using α‐actinin staining and quantitative real-time polymerase chain reaction. m6A methylation of ATF6 mediated by ALKBH5 was evaluated by methylated RNA immunoprecipitation, dual-luciferase reporter analysis, and actinomycin D treatment. Histone 3 lysine 18 lactylation (H3K18la) was evaluated using western blotting and chromatin immunoprecipitation. The results showed that ALKBH5 expression was upregulated in PE-treated cells. Knockdown of ALKBH5 decreased cell surface area and reduced the levels of hypertrophy markers in PE-induced cells, but not affected these hypertrophic phenotypes in normal H9C2 cells. Furthermore, ALKBH5 knockdown inhibited m6A demethylation of ATF6 and thus reduced its mRNA stability. Overexpression of ATF6 abrogated the inhibition of cell surface area and marker levels induced by ALKBH5 knockdown. Additionally, H3K18la was enriched in the ALKBH5 promoter and promoted transcription. Moreover, MCT1 inhibition blocked H3K18la and ALKBH5 upregulation, and H3K18R mutation abolished ALKBH5 transcription. In vivo, ALKBH5 knockdown ameliorated TAC-induced cardiac hypertrophy, which was reversed by ATF6 overexpression. In conclusion, H3K18 lactylation promotes ALKBH5 transcription, which facilitates m6A demethylation of ATF6, thereby aggravating cardiac hypertrophy. The findings provide new insights into the regulatory mechanism of cardiac hypertrophy.
