Hepatocyte estrogen-related receptor α modulates a gluconeogenic-epigenetic crosstalk counteracting MASLD/MASH progression.

Metabolic dysfunction-associated steatohepatitis (MASH) and alcoholic steatohepatitis (ASH) are severe forms of chronic liver disease, characterized by inflammation, oxidative stress, lipid dysregulation, and fibrosis. Epigenetic changes, including acetylation, methylation, phosphorylation, ubiquitination, sumoylation, and lactylation of histones, dynamically regulate gene expression by altering the chromatin structure. Emerging evidence highlights histone modifications as chief contributors to the pathogenesis of chronic liver diseases. Lactylation which is a novel post-translational modification (PTM) of histone, has been observed as a crucial contributor to liver physiology as well as pathobiology. This modification, characterized by the addition of lactate to lysine residues on histones, influences gene expression and cellular metabolism in the liver. Intriguingly, elevated lactate levels in the liver, resulting from either chronic alcohol consumption or a high-fat/fructose-rich diet, may promote histone lactylation, particularly at histone 3 at lysine 18 (H3K18), which facilitates the transcription of pro-inflammatory and fibrogenic genes. This process not only intensifies hepatic inflammation and fibrosis but also disrupts normal metabolic pathways, resulting in further liver damage. This review aims to elucidate the role of histone lactylation in MASH. Although a direct demonstration of histone lactylation in ASH has not yet been reported, the altered lactate metabolism in ASH suggests that histone lactylation may significantly contribute to its pathogenesis. Finally, we explore novel strategies targeting histone lactylation to mitigate liver injury and improve disease management in MASH and ASH.

Hepatocellular carcinoma (HCC) is a common malignant tumor. Histone lactylation, a novel epigenetic modification, plays a crucial role in various cancers. However, the functional role and underlying mechanism of histone lactylation in HCC progression have not yet been investigated. Histone lactylation levels in HCC tissues and cells were assessed using a densitometric kit and western blot analysis. The role of histone lactylation in cell malignant phenotypes was determined through functional assays in vitro, and a xenograft tumor model was established to verify the function of histone lactylation in vivo. ChIP assay was performed to explore the interaction between histone lactylation and endothelial cell-specific molecule 1 (ESM1). Additionally, gain-and-loss-of-function assays were conducted to investigate the regulatory role of ESM1 in HCC pathogenesis. Histone lactylation levels were increased in HCC tissues and cells, and H3K9 lactylation (H3K9la) and H3K56 lactylation (H3K56la) were identified as the histone modification sites. We observed that H3K9la and H3K56la caused abnormal histone lactylation and were associated with poor prognosis. Functionally, histone lactylation was found to promote HCC cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) process in vitro. However, histone lactylation inhibition with 2-deoxy-d-glucose (2-DG) reduced the malignant phenotypes of HCC cells. In vivo, 2-DG treatment reduced tumor growth and metastasis in the HCC mouse model. Mechanistically, it was revealed that histone lactylation activated ESM1 transcription in HCC cells. ESM1 was expressed at a high level in HCC and exerted a carcinogenic role. Histone lactylation facilitates cell malignant phenotypes, tumor growth, and metastasis by upregulating ESM1 expression in HCC, which reveals the downstream molecular mechanism of histone lactylation and might provide a novel therapeutic target for HCC therapy.

Lactate-Mediated Histone H3K9 Lactylation Facilitates Tumorigenesis of T-Cell Lymphoma Via Activation of SFXN1 Expression

BackgroundCirculating lactate is associated with poor prognosis in sepsis-induced acute lung injury (S-ALI). However, it remains unclear whether microvascular dysfunction, a hallmark of S-ALI, is related to circulating lactate levels and what the underlying mechanisms are. The aim of this study was to investigate the role and mechanisms of lactate in pulmonary microvascular dysfunction in S-ALI.MethodsThe effects of lactate on pulmonary microvascular function were assessed in a septic mouse model. Primary mouse pulmonary microvascular endothelial cells (MPMVECs) were isolated to evaluate the impact of lactate on MPMVEC permeability. Transcriptomic sequencing was employed to investigate the involvement of lactate in regulating MPMVEC ferroptosis, and the results were validated by in vivo and in vitro experiments. Histone lactylation was identified as a regulator of lipid peroxidation and iron homeostasis dysregulation in lactate-induced ferroptosis in MPMVECs. Gain- and loss-of-function approaches were used to assess the role of histone lactylation in regulating ferroptosis and pulmonary microvascular dysfunction. Correlations between serum lactate and ferroptosis levels and their associations with patient prognosis were investigated in patients with sepsis-associated acute respiratory distress syndrome (S-ARDS).ResultsThe mouse serum lactate level reached a peak at 18 h after caecal ligation and puncture surgery. Elevated lactate levels during sepsis promoted ferroptosis in PMVECs, leading to increased pulmonary vascular permeability and exacerbation of ALI. Mechanistically, lactate increased the lactylation of histone H3 at K18 (H3K18la), which promoted ACSL4 transcription in MPMVECs, resulting in excessive lipid peroxidation. Additionally, elevated H3K18la promoted LC3 transcription and indirectly upregulated NCOA4 expression through the transcription factor GATA2, facilitating ferritinophagy. Serum lactate levels were significantly correlated with ferroptosis levels in S-ARDS patients, and both were associated with poor patient prognosis.ConclusionsThis study revealed a critical role for high lactate-derived histone lactylation in PMVEC ferroptosis and the progression of ALI during sepsis, providing new insights and potential therapeutic mechanisms.

Elevated lactate levels are a hallmark of severe infections and are associated with poor outcomes in sepsis patients, but the underlying mechanisms remain poorly understood. Recent findings have shown that lactate can covalently modify histones (e.g., histone lactylation) in macrophages, acting as a critical epigenetic regulator of inflammatory response. Here, we demonstrate that histone lactylation also occurs in neutrophils-the first immune cells mobilized during acute inflammation-and is functionally important for their activation. Using both DMSO-differentiated HL-60 (dHL-60) cells and primary neutrophils, we found that LPS stimulation significantly increased intracellular lactate levels and histone lactylation, particularly at the H4K8 site. These changes enhanced cytokine release, ROS production, and chemotaxis. Lactate further amplified these effects, while inhibition of glycolysis or p300 suppressed them. Multi-omics analyses revealed substantial enrichment of H4K8la at the promoter region of WTAP, a key m6A methyltransferase component, promoting its expression via CEBP/β recruitment. WTAP knockdown significantly reduced m6A modifications of TLR2 mRNA and impaired its stability. Both WTAP knockdown and TLR2 inhibition markedly dampened the inflammatory responses. Importantly, this glycolysis-H4K8la-WTAP-TLR2 axis was further validated in LPS-induced septic mice and pediatric sepsis patients, highlighting its clinical relevance. In summary, our findings uncover a novel lactate-driven epigenetic-post-transcriptional regulatory circuit that amplifies neutrophil inflammatory responses, expanding the regulatory framework of innate immunity and providing potential therapeutic targets for hyperinflammation.

Changing Nomenclature from Nonalcoholic Fatty Liver Disease to Metabolic Dysfunction-Associated Fatty Liver Disease – Not Only Premature But Also Confusing

Metabolic reprogramming and epigenetic modification have been widely observed in cancer research. Based on accumulating experimental evidence in recent years, beginning with metabolic reprogramming driven by carcinogenic signals, the accumulation of key metabolites, represented by lactate, continuously affects cellular plasticity and alters the epigenetic landscape. As a new post-translational modification of histone, histone lactylation not only changes the nucleosome structure, but also regulates chromatin dynamics and gene expression, which is closely related to the poor prognosis of tumors, contributing to immune escape, immune monitoring and angiogenic events in tumor progression. Before the discovery of histone lactylation in 2019, there was a lack of systematic understanding of the lactate regulation of tumor metabolism, immune effects and microenvironmental homeostasis. From metabolic changes to stable gene expression, histone lactylation has become an important entry point in tumor research, connecting the relationship network of metabolic reprogramming, Tumor microenvironment (TME) and epigenetic modification. It represents an important conceptual link between metabolism and epigenetics, and emerging evidence suggests it may be a promising area for understanding tumor progression and developing targeted therapies. In this review, we focus on how tumor cell metabolic reprogramming reshapes the epigenetic landscape into histone lactylation. Besides, we discussed the plasticity of tumor metabolism regulated by histone lactylation in reverse, involving TME biological processes such as immunity and metabolism. Finally, we reviewed the new molecular targets and targeted therapeutic strategies of histone lactylation for cancer treatment. Elucidating these problems will provide theoretical basis for further research and clinical application in this field in the future.

Cellular senescence drives chronic sterile inflammation during aging via the senescence-associated secretory phenotype, yet the senescent cell types responsible are poorly defined. Macrophages share multiple features of senescence, including inflammatory secretion, yet whether macrophages can adopt a senescent state remains unclear. Here we identify p21⁺Trem2⁺ senescent macrophages as a major source of inflammaging, using primary mouse and human macrophage models of DNA damage and cholesterol-induced senescence characterized by multi-omic profiling. We found that senescent macrophages exhibit a distinctive p21-TREM2 expression profile and senescence-associated secretory phenotype, driven in part by type I interferon signaling via cytosolic mitochondrial DNA. We also found that senescent macrophage accumulation occurs in aging, metabolic dysfunction-associated steatotic liver disease mouse livers, and is enriched in human cirrhotic liver tissue. Finally, senolytic treatment targeting senescent macrophages reduced liver inflammation and steatosis in both aged mice and mice with metabolic dysfunction-associated steatotic liver disease. These findings establish macrophage senescence as a central driver of chronic inflammation in aging and metabolic liver disease, and a tractable therapeutic target.

Epigenetic alterations are among the prominent drivers of cellular senescence and/or aging, intricately orchestrating gene expression programs during these processes. This study shows that histone lactylation, plays a pivotal role in counteracting senescence and mitigating dysfunctions of skeletal muscle in aged mice. Mechanistically, histone lactylation and lactyl‐CoA levels markedly decrease during cellular senescence but are restored under hypoxic conditions primarily due to elevated glycolytic activity. The enrichment of histone lactylation at promoters is essential for sustaining the expression of genes involved in the cell cycle and DNA repair pathways. Furthermore, the modulation of enzymes crucial for histone lactylation, leads to reduced histone lactylation and accelerated cellular senescence. Consistently, the suppression of glycolysis and the depletion of histone lactylation are also observed during skeletal muscle aging. Modulating the enzymes can also lead to the loss of histone lactylation in skeletal muscle, downregulating DNA repair and proteostasis pathways and accelerating muscle aging. Running exercise increases histone lactylation, which in turn upregulate key genes in the DNA repair and proteostasis pathways. This study highlights the significant roles of histone lactylation in modulating cellular senescence as well as muscle aging, providing a promising avenue for antiaging intervention via metabolic manipulation.

Epigenetic modifications have been identified as critical molecular determinants influencing macrophage plasticity and heterogeneity. Among these, histone lactylation is a recently discovered epigenetic modification. Research examining the effects of histone lactylation on macrophage activation and polarization has grown substantially in recent years. Evidence increasingly suggests that lactate-mediated changes in histone lactylation levels within macrophages can modulate gene transcription, thereby contributing to the pathogenesis of various diseases. This review provides a comprehensive analysis of the role of histone lactylation in macrophage activation, exploring its discovery, effects, and association with macrophage diversity and phenotypic variability. Moreover, it highlights the impact of alterations in macrophage histone lactylation in diverse pathological contexts, such as inflammation, tumorigenesis, neurological disorders, and other complex conditions, and demonstrates the therapeutic potential of drugs targeting these epigenetic modifications. This mechanistic understanding provides insights into the underlying disease mechanisms and opens new avenues for therapeutic intervention.

ASF1A-dependent P300-mediated histone H3 lysine 18 lactylation promotes atherosclerosis by regulating EndMT

The Warburg effect, originally describing augmented lactogenesis in cancer, is associated with diverse cellular processes such as angiogenesis, hypoxia, macrophage polarization, and T-cell activation. This phenomenon is intimately linked with multiple diseases including neoplasia, sepsis, and autoimmune diseases1,2. Lactate, a compound generated during Warburg effect, is widely known as an energy source and metabolic byproduct. However, its non-metabolic functions in physiology and disease remain unknown. Here we report lactate-derived histone lysine lactylation as a new epigenetic modification and demonstrate that histone lactylation directly stimulates gene transcription from chromatin. In total, we identify 28 lactylation sites on core histones in human and mouse cells. Hypoxia and bacterial challenges induce production of lactate through glycolysis that in turn serves as precursor for stimulating histone lactylation. Using bacterially exposed M1 macrophages as a model system, we demonstrate that histone lactylation has different temporal dynamics from acetylation. In the late phase of M1 macrophage polarization, elevated histone lactylation induces homeostatic genes involved in wound healing including arginase 1. Collectively, our results suggest the presence of an endogenous “lactate clock” in bacterially challenged M1 macrophages that turns on gene expression to promote homeostasis. Histone lactylation thus represents a new avenue for understanding the functions of lactate and its role in diverse pathophysiological conditions, including infection and cancer.

Tissue regeneration relies on precise molecular mechanisms controlling cell-fate transitions, with metabolism emerging as a key regulator. Lactate-derived histone lactylation has recently been identified as an epigenetic modification regulating gene expression across various biological processes. Here, we report an increase in global histone lactylation in the mesenchyme and osteoblasts of the zebrafish caudal fin during early regeneration. Our findings demonstrate that this epigenetic modification is functionally regulated by increased lactate levels, while the inhibition of glycolysis and lactate production significantly reduces histone lactylation. Transcriptomic profiling under reduced lactylation revealed the downregulation of proliferative and chromatin-remodeling programs. This suggests a model in which injury-induced, lactate-driven histone lactylation sustains chromatin accessibility and promotes proliferative transcription during early regeneration, potentially modulating gene expression essential for cell plasticity and proliferation. This study identifies histone lactylation as a metabolic-epigenetic regulator of regenerative programs, providing mechanistic insights for the development of novel therapeutic strategies to enhance tissue repair.

Histone lactylation and N6-methyladenosine (m6A) alteration are epigenetic modifications that have a crucial function in controlling gene expression throughout fibroblast activation and organ fibrosis. However, their roles in sepsis-associated pulmonary fibrosis (SAPF) remain unclear. This study established a mouse and cell model induced by lipopolysaccharides (LPS) to investigate the possible mechanisms of lactylation and METTL3-mediated m6A RNA modification in pulmonary fibroblast activation and sepsis-associated PF. The gene expression of m6A modification and lactylation in pulmonary fibroblasts of LPS-induced PF mouse model was examined using scRNA-Seq. Moreover, METTL3 short hairpin RNA (shRNA) and adeno-associated virus (AAV) were employed to knockdown METTL3 expression, and the glycolysis inhibitor Oxamate was utilized to attenuate lactate production and histone lactylation. Furthermore, to confirm the target gene controlled by m6A and H3K18 lactylation (H3K18la), ChIP-qPCR and RNA pulldown investigations were carried out. Single-cell RNA-sequencing unveiled the promotion of m6A modification and lactylation in pulmonary fibroblasts of LPS-induced PF mouse model. Furthermore, the induction of LPS resulted in an elevation of H3K18la lactylation and METTL3 concentrations, a reduction in PGC-1α levels, and the onset of mitochondrial dysfunction, all of which contribute to the activation of lung fibroblasts and the development of pulmonary fibrosis. Therapeutic effectiveness was observed in both in vitro and in vivo settings through focused rectification of abnormal histone lactylation or by reducing the expression of METTL3. Our study demonstrates, LPS-induced histone lactylation contributes to sepsis-induced pulmonary fibrosis by upregulating METTL3 expression. Additionally, METTL3 recognizes m6A-modified PGC-1α mRNAs, leading to mitochondrial dysfunction and accelerated fibroblast activation, ultimately driving pulmonary fibrosis. METTL3-mediated m6A modification potently degraded PGC-1α, leading to mitochondrial dysfunction and accelerated fibroblast activation, ultimately driving Sepsis-Associated PF. This suggests that the presence of histone lactylation in the fibrotic microenvironment associated with sepsis plays a crucial role in triggering the expression and activity of the RNA methyltransferase METTL3.

Metabolic dysfunction-associated fatty liver disease is a significant risk factor for cardiovascular disease (CVD). This study assesses the association between leisure-time physical activity, sedentary behavior, and CVD risk among patients with metabolic dysfunction-associated fatty liver disease, considering genetic predisposition to CVD. This cohort study included 157 794 participants with metabolic dysfunction-associated fatty liver disease from the UK Biobank who were free of CVD at baseline. The study measured leisure-time sedentary behaviors (watching TV, using a computer, and driving) and physical activities (walking for pleasure, light and heavy do-it-yourself activities, strenuous sports, and other exercises) in terms of frequency and duration over the 4 weeks before assessment. Both a Cox proportional hazard model and an isotemporal substitution model were utilized in the study to assess the association between leisure sedentary behavior, physical activities, and CVD risk. During a median 12.5 years of follow-up, 26 355 CVD cases were reported, including 19 746 coronary heart disease, 4836 stroke, and 7398 heart failure cases. High physical activity levels were linked to a significantly lower risk of CVD (21%), coronary heart disease (20%), stroke (15%), and heart failure (31%). In contrast, individuals with >6.5 h/d of sedentary behavior faced a 16% to 21% higher risk of these conditions compared with those with ≤3.5 h/d. Notably, replacing 30 minutes of inactivity with physical activity reduced CVD risks by 3% to 16%, particularly with strenuous sports. A significant interaction was observed between physical activity, sedentary behavior, and genetic predisposition in relation to stroke risk. Among patients with metabolic dysfunction-associated fatty liver disease, higher leisure-time physical activity levels correlate with reduced CVD risks, while increased sedentary behavior is linked to higher CVD risks. Replacing sedentary time with physical activity consistently shows benefits in reducing CVD outcomes, irrespective of genetic predisposition.