Herrmann, Joerg

Abstract Metabolic reprogramming is a fundamental determinant of immune cell fate and effector function during inflammation, yet how distinct metabolic pathways regulate pathogenic lung macrophage activity and contribute to fibrotic remodeling remains incompletely understood. Here, we integrated single-cell RNA sequencing, lineage-specific genetic mouse models, and fate-mapping approaches to define the metabolic pathways that regulate the pro-fibrotic activity of lung macrophages. We found that such cells undergo pronounced aerobic glycolysis in the bleomycin-induced mouse model of pulmonary fibrosis. Myeloid cell-specific depletion of lactate dehydrogenase A (Ldha), but not of mitochondrial pyruvate carrier (Mpc), markedly attenuated lung fibrosis and improved survival. Mechanistically, enhanced glycolytic flux increased lactate production, which promoted histone lysine lactylation and facilitated Arginase 1 (Arg1) expression in lung macrophages, thereby driving fibrotic progression. Using monocyte fate-mapping, we further demonstrated that Arg1 expression is largely restricted to recruited monocyte-derived macrophages rather than lung-resident macrophages. Notably, selective deletion of Ldha in granulocyte-monocyte progenitors and their progeny was sufficient to suppress Arg1 expression and reduce fibrosis severity. In human lung samples, we observed significantly elevated expression of ARG1 and key glycolytic enzymes in patients with idiopathic pulmonary fibrosis, despite species-specific differences in the immune cell types expressing ARG1. Together, these findings identify an aerobic glycolysis–lactate–histone lactylation axis that regulates pro-fibrotic myeloid cell function and represents a potential therapeutic target in pulmonary fibrosis.

This cohort study examines the association of bruton tyrosine kinase inhibitor therapy in B-cell malignant disease with increased risk of pericardial effusion and cardiovascular outcomes.

Significance: Immune checkpoint inhibitors (ICIs) have transformed cancer therapy by reactivating antitumor immunity and improving outcomes across multiple malignancies. Yet, clinical observations and preclinical studies suggest that ICIs may increase long-term cardiovascular disease risk, including hypertension, atherosclerosis, and thrombosis. The underlying mechanisms remain incompletely defined, highlighting the need for focused investigation into the vascular consequences of immune activation. Recent Advances: ICI-induced immune activation disrupts vascular and immune homeostasis through persistent production of reactive oxygen species (ROS), mitochondrial dysfunction, and accumulation of cell-free DNA (cfDNA). Sustained T-cell activation enhances ROS generation, driving DNA damage and senescence in both endothelial and immune cells. ICIs may also promote endothelial-to-mesenchymal transition (EndoMT) through chronic oxidative and inflammatory signaling, contributing to fibrosis, vascular stiffness, and chronic inflammation. Transforming growth factor-beta, although immunosuppressive in many contexts, can drive profibrotic and EndoMT programs within the vasculature. Other cytokines and regulators, including interleukin-17 and regulator of calcineurin 1, have been implicated in vascular remodeling, atherosclerosis, and hypertension. Critical Issues: The relative roles of ROS, mitochondrial dysfunction, cfDNA-driven inflammation, and EndoMT in ICI-associated vascular senescence remain unclear. While inflammation-induced vascular damage is well-recognized, direct ICI-specific mechanisms require stronger evidence. How senescent endothelial and immune cells influence therapy resistance and remodeling of the tumor microenvironment also remains to be defined. Future Directions: Mitochondrial and cytosolic ROS sources—arising from electron leakage during oxidative phosphorylation and NADPH oxidases activity—shape immune signaling and sustain T-cell activation during checkpoint blockade. The DNA damage response kinases ataxia-telangiectasia mutated and ATM- and Rad3-related, activated by oxidative and replicative stress, engage p53-dependent senescence pathways in endothelial and immune cells. Future studies should evaluate biomarkers such as cfDNA and thrombospondin-1 and explore senescence-targeting or redox-modulating interventions that may alleviate cardiovascular toxicity without diminishing antitumor efficacy. This review outlines mechanistic pathways linking ICIs to vascular dysfunction and senescence, integrating preclinical data with emerging clinical insights. It distinguishes established processes from ICI-specific hypotheses and identifies key gaps requiring clinical validation. Antioxid. Redox Signal. 00, 000–000.