Shikonin ameliorated mice colitis by inhibiting dimerization and tetramerization of PKM2 in macrophages

LincRNA-miR interactions in hepatocellular carcinoma: comprehensive review and in silico analysis: a step toward ncRNA precision

The most prevalent form of primary liver cancer and one of the chief drivers of cancer-related mortality globally is hepatocellular carcinoma (HCC). Imminent evidence has indicated that non-coding RNAs (ncRNAs) play an integral part in the development and propagation of HCC. RNA stabilization, transcription regulation, chromatin and genomic architecture remodeling, enhancer-associated activity, and other varied properties set long intergenic ncRNA (lincRNA) genes apart from messenger RNA (mRNA)-encoding genes. Through a variety of processes, lincRNAs may generally be used to fine-tune the transcription of nearby genes with exceptional tissue specificity, underscoring our quickly developing knowledge of the non-coding genome. Through their binding with divergent cell targets, some HCC-related ncRNAs have been demonstrated to exhibit abnormal expression, contribute to malignant growth, evade apoptosis, and have invasive potential. Therefore, a better comprehension of lincRNA dysregulation might offer novel perspectives on the pathophysiology of HCC as well as innovative instruments for the early detection and management of HCC. In the present review, we provide an overview of the increasing relevance of lincRNAs as a major contributor to the pathophysiology of HCC, emphasizing their influence on signaling pathways implicated in the development, progression, and response to treatment of tumors. In addition, we go over the new approaches that target lincRNAs for HCC treatment as well as the possible therapeutic uses of lincRNAs as prognostic and diagnostic biomarkers for HCC.

The role of PKM2-mediated metabolic reprogramming in the osteogenic differentiation of BMSCs under diabetic periodontitis conditions

BACKGROUND

Diabetes mellitus (DM) and periodontitis have a bidirectional relationship, with each being a high-risk factor for the other. Prolonged hyperglycemia exacerbates periodontal inflammation and disrupts bone homeostasis. Pyruvate kinase M2 (PKM2), a key enzyme in glycolysis, is involved in metabolic reprogramming, but its role in osteogenesis under high-glucose (HG) inflammatory conditions remains largely unknown. This study aimed to investigate the effects of HG and inflammation on bone marrow mesenchymal stem cells (BMSCs) under indirect co-culture conditions and to explore how PKM2 regulates metabolism and mitochondrial function during osteogenic differentiation in HG inflammatory environments, elucidating its role in diabetic periodontitis (DP).

METHODS

Expose BMSCs to conditioned medium (CM) collected from RAW264.7 cells stimulated with HG and/or lipopolysaccharide (LPS). BMSCs functionality was assessed using CCK8, EdU, Annexin V-PI apoptosis assay, alkaline phosphatase (ALP), and Alizarin Red S (ARS) staining. Metabolic characteristics were evaluated through Seahorse assays, lactate production, glucose uptake, and ATP measurements. Mitochondrial function was assessed via JC-1, and ROS staining, Mito-Tracker staining, and transmission electron microscopy (TEM). Gene and protein expression were analyzed by quantitative real-time PCR and western blotting. In vivo therapeutic effects of shikonin were validated via micro-CT and histological staining in a diabetic periodontitis mouse model.

RESULTS

In vitro experiments demonstrated that HG inflammatory conditions impaired the survival of BMSCs, suppressed osteogenic differentiation, and induced metabolic reprogramming. This reprogramming was characterized by enhanced glycolysis, impaired oxidative phosphorylation (OXPHOS), abnormal upregulation of PKM2 expression, and mitochondrial dysfunction accompanied by morphological alterations. Shikonin effectively reversed these adverse effects by inhibiting PKM2 tetramerization, rescuing the loss of osteogenic function in BMSCs. The therapeutic potential of shikonin was confirmed in the diabetic periodontitis mouse model.

CONCLUSION

PKM2 impairs the osteogenesis of BMSCs by affecting metabolism and mitochondrial function, suggesting it as a potential therapeutic target for diabetic periodontitis.

The role of natural products targeting macrophage polarization in sepsis-induced lung injury

Sepsis-induced acute lung injury (SALI) is characterized by a dysregulated inflammatory and immune response. As a key component of the innate immune system, macrophages play a vital role in SALI, in which a macrophage phenotype imbalance caused by an increase in M1 macrophages or a decrease in M2 macrophages is common. Despite significant advances in SALI research, effective drug therapies are still lacking. Therefore, the development of new treatments for SALI is urgently needed. An increasing number of studies suggest that natural products (NPs) can alleviate SALI by modulating macrophage polarization through various targets and pathways. This review examines the regulatory mechanisms of macrophage polarization and their involvement in the progression of SALI. It highlights how NPs mitigate macrophage imbalances to alleviate SALI, focusing on key signaling pathways such as PI3K/AKT, TLR4/NF-κB, JAK/STAT, IRF, HIF, NRF2, HMGB1, TREM2, PKM2, and exosome-mediated signaling. NPs influencing macrophage polarization are classified into five groups: terpenoids, polyphenols, alkaloids, flavonoids, and others. This work provides valuable insights into the therapeutic potential of NPs in targeting macrophage polarization to treat SALI.

GP73-mediated secretion of PKM2 and GP73 promotes angiogenesis and M2-like macrophage polarization in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. Abnormally high expression of Golgi protein 73 (GP73) and pyruvate kinase M2 (PKM2) is intimately associated with HCC progression. However, as secreted proteins, the role of their extracellular secretions in HCC progression remains unclear. Here, we demonstrated that the expression of extracellular GP73 was positively correlated with extracellular PKM2. GP73 interacted with PKM2 to promote SUMO1 modification of PKM2, which in turn enhanced the interaction of GP73 and PKM2. This process continuously promoted the transfer of PKM2 from the cytoplasm to the membrane in HCC cells, and finally secretion. Extracellular PKM2 and GP73 synergistically promoted angiogenesis and polarization of M2-type macrophages, thereby leading to malignant progression and sorafenib resistance in HCC. Sorafenib combined with shikonin, a specific inhibitor of PKM2, has a strong anti-tumor effect. This study reveals the role of GP73 in enhancing PKM2 and GP73 secretion in promoting HCC progression, providing a theoretical basis and drug targets for HCC therapy.

PKM2-mediated STAT3 phosphorylation promotes acute liver failure via regulating NLRP3-dependent pyroptosis

Acute liver failure (ALF) is a life-threatening clinical syndrome characterized by high-grade inflammation and multi-organ failure. Our previous study shows that targeting the M2 isoform of pyruvate kinase (PKM2) to inhibit macrophage inflammation may be a promising strategy for ALF treatment. however, the mechanism by which PKM2 regulates the inflammatory response is unclear. Here we demonstrate that PKM2 contributes to ALF by modulating NLRP3-mediated pyroptosis activation in liver macrophages. The specific knockout of PKM2 in myeloid cells reduces mortality and alleviates hepatic injury in D-galactosamine/LPS-induced ALF mice. Single-cell transcriptome analysis suggests that NLRP3 inflammasome activation of macrophages involves in ALF, knockout of PKM2 in macrophages reduces the expression of NLRP3, and activation of pyroptosis. Pharmacological inhibition of the PKM2 nuclear translocation, but not glycolytic activity, protects mice from ALF. Pharmacological and genetic inhibition of PKM2 attenuates NLRP3-mediated pyroptosis activation and consequently reduces the release of IL-1β and IL-18 by macrophages. Mechanistically, PKM2 translocates into the nucleus and combines with STAT3, enhancing its phosphorylation and recruitment to the NLRP3 promoter region, thereby increasing NLRP3 expression. This work defines PKM2 acts as an important nonmetabolic regulator of NLRP3 that modulates pyroptosis activation in macrophages and guides future therapeutic strategies development for ALF.

Shikonin mitigates cyclophosphamide-induced cardiotoxicity in mice: the role of sirtuin-1, NLRP3 inflammasome, autophagy, and apoptosis

OBJECTIVES

The aim of this study was to elucidate the protective potential of shikonin (SHK) on cyclophosphamide (CP)-induced cardiotoxicity in Swiss albino mice.

METHODS

Mice received SHK in three different doses by oral gavage daily for 14 days and CP at 100 mg/kg, intraperitoneally once on the seventh day. On the 15th day, mice were euthanized, blood collected, and hearts were removed to estimate various biochemical and histopathological parameters.

KEY FINDINGS

CP significantly increased serum lactate dehydrogenase, creatine kinase-MB, troponin I and NT pro-BNP, and cardiac malondialdehyde and decreased cardiac total antioxidant capacity and Nrf2, whereas increased inflammatory markers in the cardiac tissues. CP also caused hypertrophy and fibrosis in the cardiac tissues via activation of IL6/JAK2/STAT3 while depressed SIRT1 and PI3K/p-Akt pathway with consequent increased apoptosis and dysregulation of autophagy. SHK treatment reversed these changes in a dose-dependent manner and showed a significant protective effect against CP-induced cardiotoxicity via suppressing oxidative stress, inflammation, and apoptosis with modulation of autophagy via induction of SIRT1/PI3K/p-Akt signaling.

CONCLUSIONS

Shikonin may be used as an adjuvant to cyclophosphamide in cancer treatment, but further research is needed to investigate its effects on cardiotoxicity in distinct animal cancer models.

Shikonin alleviates asthma phenotypes in mice via an airway epithelial STAT3-dependent mechanism

Background

Asthma is an inflammatory disease where the balance between Th1/Th2 and Th17/Treg plays a crucial role in its pathogenesis. Shikonin is used to treat a variety of autoimmune diseases due to its good anti-inflammatory activity. However, the effect and mechanism of shikonin on asthma remain unknown.

Method

Mice were sensitized with ovalbumin (OVA)/house dust mite (HDM) and treated with shikonin. Lung inflammation was assessed histologically and via flow cytometry. Bronchoalveolar lavage fluid (BALF) was analyzed for cell counts and cytokines. Shikonin's impact on p-STAT3 was studied in vivo and in vitro.

Results

Shikonin inhibited OVA or HDM-induced inflammation and airway hyperresponsiveness. Upon treatment, a restoration of the Th1/Th2 and Th17/Treg balance was observed, evidenced by a reduction in IL-4 and IL-17A levels in BALF, alongside an elevation in interferon-gamma and IL-10. Furthermore, shikonin impeded the infiltration of eosinophils, neutrophils, macrophages, and lymphocytes into lung tissue. The observed decrease in STAT3 phosphorylation and diminished nuclear translocation of p-STAT3 confirmed that shikonin promotes the balance of Th1/Th2 and Th17/Treg by regulating airway epithelial STAT3.

Conclusion

Shikonin mitigates asthma symptoms through a STAT3-dependent mechanism, indicating its potential as an anti-asthmatic therapeutic agent.

The Activation of PKM2 Induces Pyroptosis in Hippocampal Neurons via the NLRP3/Caspase-1/GSDMD Pathway in Neonatal Rats With Hypoxic-Ischemic Brain Injury

INTRODUCTION

The presence of hypoxic-ischemic brain damage (HIBD) in neonates triggers a strong neuroinflammatory reaction. Pyroptosis, a programmed cell death mechanism associated with inflammation, plays a crucial role in HIBD. Pyruvate kinase M2 (PKM2) plays a significant role in connecting metabolic processes and inflammatory responses, but whether it affects hippocampus pyroptosis in HIBD is unclear. The aim of this study is to elucidate the role of PKM2 in HIBD and to propose a novel therapeutic approach for neonatal ischemic-hypoxic encephalopathy.

METHODS

In this study, we employed neonatal 7-day-old Sprague Dawley rats to establish a model of HIBD using the Rice-Vannucci surgical technique and a hypoxia device. To inhibit the elevation of PKM2, we utilized the PKM2 inhibitor shikonin. The rats were categorized into four groups: Sham, Shikonin, HIBD, and Shikonin + HIBD. Behavioral tests, hematoxylin eosin staining, immunofluorescence staining, ELISA (IL-1β, IL-18), and LDH were conducted in each group to evaluate neurological function, hippocampal damage, the occurrence of neuronal pyroptosis, and the neuroinflammation. Western blot was used to assess the expression levels of PKM2, NLRP3, Caspase-1, Cleaved Caspase-1, GSDMD, GSDMDN, and IL-1β.

RESULTS

The expression of PKM2 elevated in hippocampal tissues of the HIBD model and the localization of PKM2 in the hippocampus was activated in neurons instead of microglia during the HIBD. Meanwhile, the inhibition of PKM2 improved the behavioral test scores and the body weight of rats, the neuronal damage in the CA1 region of hippocampal tissue was also attenuated. In addition, inhibiting PKM2 alleviated neuronal pyroptosis by decreasing the expression of PKM2, NLRP3, Caspase-1, Cleaved Caspase-1, GSDMD, GSDMDN. Furthermore, serum levels of LDH and inflammatory factors IL-1β and IL-18 decrease with PKM2 inhibition.

CONCLUSIONS

Based on these findings, we can conclude that PKM2 plays a crucial role in regulating hippocampal neuronal pyroptosis of HIBD rats via NLRP3/Caspase-1/GSDMD pathway. Therefore, inhibiting PKM2 could be a promising therapeutic strategy for the treatment of neonatal ischemic-hypoxic encephalopathy.

Targeting Lactate: An Emerging Strategy for Macrophage Regulation in Chronic Inflammation and Cancer

Lactate accumulation and macrophage infiltration are pivotal features of both chronic inflammation and cancer. Lactate, once regarded merely as an aftereffect of glucose metabolism, is now gaining recognition for its burgeoning spectrum of biological roles and immunomodulatory significance. Recent studies have evidenced that macrophages display divergent immunophenotypes in different diseases, which play a pivotal role in disease management by modulating macrophage polarization within the disease microenvironment. The specific polarization patterns of macrophages in a high-lactate environment and their contribution to the progression of chronic inflammation and cancer remain contentious. This review presents current evidence on the crosstalk of lactate and macrophage in chronic inflammation and cancer. Additionally, we provide an in-depth exploration of the pivotal yet enigmatic mechanisms through which lactate orchestrates disease pathogenesis, thereby offering novel perspectives to the development of targeted therapeutic interventions for chronic inflammation and cancer.

Oxidized LDL regulates efferocytosis through the CD36-PKM2-mtROS pathway

Macrophage efferocytosis, the process by which phagocytes engulf and remove apoptotic cells (ACs), plays a critical role in maintaining tissue homeostasis. Efficient efferocytosis prevents secondary necrosis, mitigates chronic inflammation, and impedes atherosclerosis progression. However, the regulatory mechanisms of efferocytosis under atherogenic conditions remain poorly understood. We previously demonstrated that oxidized LDL (oxLDL), an atherogenic lipoprotein, induces mitochondrial reactive oxygen species (mtROS) in macrophages via CD36. In this study, we demonstrate that macrophage mtROS facilitate continual efferocytosis through a positive feedback mechanism. However, oxLDL disrupts continual efferocytosis by dysregulating the internalization of ACs. This disruption is mediated by an overproduction of mtROS. Mechanistically, oxLDL/CD36 signaling promotes the translocation of cytosolic PKM2 to mitochondria, facilitated by the chaperone GRP75. Mitochondrial PKM2 then binds to Complex III of the electron transport chain, inducing mtROS production. This study elucidates a novel regulatory mechanism of efferocytosis in atherosclerosis, providing potential therapeutic targets for intervention.

SUMMARY

Macrophages clear apoptotic cells through a process called efferocytosis, which involves mitochondrial ROS. However, the atherogenic oxidized LDL overstimulates mitochondrial ROS via the CD36-PKM2 pathway, disrupting continual efferocytosis. This finding elucidates a novel molecular mechanism that explains defects in efferocytosis, driving atherosclerosis progression.

Polyphenols: immunonutrients tipping the balance of immunometabolism in chronic diseases

Mounting evidence progressively appreciates the vital interplay between immunity and metabolism in a wide array of immunometabolic chronic disorders, both autoimmune and non-autoimmune mediated. The immune system regulates the functioning of cellular metabolism within organs like the brain, pancreas and/or adipose tissue by sensing and adapting to fluctuations in the microenvironment's nutrients, thereby reshaping metabolic pathways that greatly impact a pro- or anti-inflammatory immunophenotype. While it is agreed that the immune system relies on an adequate nutritional status to function properly, we are only just starting to understand how the supply of single or combined nutrients, all of them termed immunonutrients, can steer immune cells towards a less inflamed, tolerogenic immunophenotype. Polyphenols, a class of secondary metabolites abundant in Mediterranean foods, are pharmacologically active natural products with outstanding immunomodulatory actions. Upon binding to a range of receptors highly expressed in immune cells (e.g. AhR, RAR, RLR), they act in immunometabolic pathways through a mitochondria-centered multi-modal approach. First, polyphenols activate nutrient sensing via stress-response pathways, essential for immune responses. Second, they regulate mammalian target of rapamycin (mTOR)/AMP-activated protein kinase (AMPK) balance in immune cells and are well-tolerated caloric restriction mimetics. Third, polyphenols interfere with the assembly of NLR family pyrin domain containing 3 (NLRP3) in endoplasmic reticulum-mitochondria contact sites, inhibiting its activation while improving mitochondrial biogenesis and autophagosome-lysosome fusion. Finally, polyphenols impact chromatin remodeling and coordinates both epigenetic and metabolic reprogramming. This work moves beyond the well-documented antioxidant properties of polyphenols, offering new insights into the multifaceted nature of these compounds. It proposes a mechanistical appraisal on the regulatory pathways through which polyphenols modulate the immune response, thereby alleviating chronic low-grade inflammation. Furthermore, it draws parallels between pharmacological interventions and polyphenol-based immunonutrition in their modes of immunomodulation across a wide spectrum of socioeconomically impactful immunometabolic diseases such as Multiple Sclerosis, Diabetes (type 1 and 2) or even Alzheimer's disease. Lastly, it discusses the existing challenges that thwart the translation of polyphenols-based immunonutritional interventions into long-term clinical studies. Overcoming these limitations will undoubtedly pave the way for improving precision nutrition protocols and provide personalized guidance on tailored polyphenol-based immunonutrition plans.

Phytochemicals Target Multiple Metabolic Pathways in Cancer

Cancer metabolic reprogramming is a complex process that provides malignant cells with selective advantages to grow and propagate in the hostile environment created by the immune surveillance of the human organism. This process underpins cancer proliferation, invasion, antioxidant defense, and resistance to anticancer immunity and therapeutics. Perhaps not surprisingly, metabolic rewiring is considered to be one of the "Hallmarks of cancer". Notably, this process often comprises various complementary and overlapping pathways. Today, it is well known that highly selective inhibition of only one of the pathways in a tumor cell often leads to a limited response and, subsequently, to the emergence of resistance. Therefore, to increase the overall effectiveness of antitumor drugs, it is advisable to use multitarget agents that can simultaneously suppress several key processes in the tumor cell. This review is focused on a group of plant-derived natural compounds that simultaneously target different pathways of cancer-associated metabolism, including aerobic glycolysis, respiration, glutaminolysis, one-carbon metabolism, de novo lipogenesis, and β-oxidation of fatty acids. We discuss only those compounds that display inhibitory activity against several metabolic pathways as well as a number of important signaling pathways in cancer. Information about their pharmacokinetics in animals and humans is also presented. Taken together, a number of known plant-derived compounds may target multiple metabolic and signaling pathways in various malignancies, something that bears great potential for the further improvement of antineoplastic therapy.

Electroacupuncture alleviates ulcerative colitis by targeting CXCL1: evidence from the transcriptome and validation

Background

We aimed to use transcriptomics, bioinformatics analysis, and core gene validation to identify the core gene and potential mechanisms for electroacupuncture (EA) treatment of ulcerative colitis (UC).

Materials and methods

EA was performed in mice after induction of UC via dextran sodium sulfate. Body weight, disease activity index (DAI), colon length, and hematoxylin-eosin of the colon tissue were used to evaluate the effects of EA. Mice transcriptome samples were analyzed to identify the core genes, and further verified with human transcriptome database; the ImmuCellAI database was used to analyze the relationship between the core gene and immune infiltrating cells (IICs); and immunofluorescence was used to verify the results.

Results

EA could reduce DAI and histological colitis scores, increase bodyweight and colon length, and improve the expression of local and systemic proinflammatory factors in the serum and colon of UC mice. Eighteen co-differentially expressed genes were identified by joint bioinformatics analyses of mouse and human transcriptional data; Cxcl1 was the core gene. EA affected IICs by inhibiting Cxcl1 expression and regulated the polarization of macrophages by affecting the Th1 cytokine IFN-γ, inhibiting the expression of CXCL1.

Conclusions

CXCL1 is the target of EA, which is associated with the underlying immune mechanism related to Th1 cytokine IFN-γ.

Glycolysis in Chronic Liver Diseases: Mechanistic Insights and Therapeutic Opportunities

Chronic liver diseases (CLDs) cover a spectrum of liver diseases, ranging from nonalcoholic fatty liver disease to liver cancer, representing a growing epidemic worldwide with high unmet medical needs. Glycolysis is a conservative and rigorous process that converts glucose into pyruvate and sustains cells with the energy and intermediate products required for diverse biological activities. However, abnormalities in glycolytic flux during CLD development accelerate the disease progression. Aerobic glycolysis is a hallmark of liver cancer and is responsible for a broad range of oncogenic functions including proliferation, invasion, metastasis, angiogenesis, immune escape, and drug resistance. Recently, the non-neoplastic role of aerobic glycolysis in immune activation and inflammatory disorders, especially CLD, has attracted increasing attention. Several key mediators of aerobic glycolysis, including HIF-1α and pyruvate kinase M2 (PKM2), are upregulated during steatohepatitis and liver fibrosis. The pharmacological inhibition or ablation of PKM2 effectively attenuates hepatic inflammation and CLD progression. In this review, we particularly focused on the glycolytic and non-glycolytic roles of PKM2 in the progression of CLD, highlighting the translational potential of a glycolysis-centric therapeutic approach in combating CLD.

A new strategy for osteoarthritis therapy: Inhibition of glycolysis

Osteoarthritis (OA) is a common degenerative disease of the joints. It is primarily caused by age, obesity, mechanical damage, genetics, and other factors, leading to cartilage degradation, synovial inflammation, and subchondral sclerosis with osteophyte formation. Many recent studies have reported that glycolysis disorders are related lead to OA. There is a close relationship between glycolysis and OA. Because of their hypoxic environment, chondrocytes are highly dependent on glycolysis, their primary energy source for chondrocytes. Glycolysis plays a vital role in OA development. In this paper, we comprehensively summarized the abnormal expression of related glycolytic enzymes in OA, including Hexokinase 2 (HK2), Pyruvate kinase 2 (PKM2), Phosphofructokinase-2/fructose-2, 6-Bisphosphatase 3 (PFKFB3), lactate dehydrogenase A (LDHA), and discussed the potential application of glycolysis in treating OA. Finally, the natural products that can regulate the glycolytic pathway were summarized. Targeting glucose transporters and rate-limiting enzymes to glycolysis may play an essential role in treating OA.