Mitochondrial DNA in liver inflammation and oxidative stress

Unveiling the role of mtDNA in Liver-Kidney Crosstalk: Insights from trichloroethylene hypersensitivity syndrome

In specific pathological conditions, addressing liver injury may yield favorable effects on renal function through the phenomenon of liver-kidney crosstalk. Mitochondrial DNA (mtDNA) possesses the capability to trigger downstream pathways of inflammatory cytokines, ultimately leading to immune-mediated organ damage. Consequently, understanding the intricate molecular mechanisms governing mtDNA involvement in diseases characterized by liver-kidney crosstalk is of paramount significance. This study seeks to elucidate the role of mtDNA in conditions marked by liver-kidney crosstalk. In previous clinical cases, it has been observed that patients with Trichloroethylene Hypersensitivity Syndrome (TCE-HS) who experience severe liver injury often also exhibit renal injury. In this study, patients diagnosed with trichloroethylene hypersensitivity syndrome were recruited from Shenzhen Occupational Disease Control Center. And Balb/c mice were treated with trichloroethylene. The correlation between liver and kidney injuries in patients with TCE-HS was assessed using Enzyme-Linked Immunosorbent Assay (ELISA). Alterations in mtDNA levels were examined in mouse hepatocytes, red blood cells (RBCs), and renal tubular epithelial cells utilizing immunofluorescence and PCR techniques. TCE-sensitized mice exhibited a significant increase in reactive oxygen species (ROS) and the opening of the mitochondrial permeability transition pore in hepatocytes, resulting in the release of mtDNA. Furthermore, heightened levels of mtDNA and Toll-like Receptor 9 (TLR9) expression were observed in RBCs. Additional experiments demonstrated elevated expression of TLR9 and its downstream mediator MyD88 in renal tubule epithelial cells of TCE-sensitized mice. In vitro investigations confirmed that mtDNA activates the TLR9 pathway in TCMK-1 cells. Collectively, these results suggest that mtDNA released from mitochondrial damage in hepatocytes is carried by RBCs to renal tubular epithelial cells and mediates inflammatory injury in renal tubular epithelial cells through activation of the TLR9 receptor.

The role of mitochondrial dysfunction in kidney injury and disease

Mitochondria are the main sites of aerobic respiration in the cell and mainly provide energy for the organism, and play key roles in adenosine triphosphate (ATP) synthesis, metabolic regulation, and cell differentiation and death. Mitochondrial dysfunction has been identified as a contributing factor to a variety of diseases. The kidney is rich in mitochondria to meet energy needs, and stable mitochondrial structure and function are essential for normal kidney function. Recently, many studies have shown a link between mitochondrial dysfunction and kidney disease, maintaining mitochondrial homeostasis has become an important target for kidney therapy. In this review, we integrate the role of mitochondrial dysfunction in different kidney diseases, and specifically elaborate the mechanism of mitochondrial reactive oxygen species (mtROS), autophagy and ferroptosis involved in the occurrence and development of kidney diseases, providing insights for improved treatment of kidney diseases.

Discovery of new 2-(3-(naphthalen-2-yl)-4,5-dihydro-1H-pyrazol-1-yl)thiazole derivatives with potential analgesic and anti-inflammatory activities: In vitro, in vivo and in silico investigations

Joining the global demand for the discovery of potent NSAIDs with minimized ulcerogenic effect, new pyrazole clubbed thiazole derivatives 5a-o were designed and synthesized. The new derivatives were initially evaluated for their analgesic activity. Eight compounds 5a, 5c, 5d, 5e, 5f, 5h, 5m, and 5o showed higher activity than Indomethacin (potency = 105-130 % vs. 100 %). Subsequently, they were picked for further evaluation of their anti-inflammatory activity, ulcerogenic liability as well as toxicological studies. Derivatives 5h and 5m showed a potential % edema inhibition after 3 h (79.39 % and 72.12 %, respectively), with a promising safety profile and low ulcer indices (3.80 and 3.20, respectively). The two compounds 5h and 5m were subjected to in vitro COX-1 and COX-2 inhibition assay. The candidate 5h showed nearly equipotent COX-1 inhibition (IC50 = 38.76 nM) compared to the non-selective reference drug Indomethacin (IC50 = 35.72 nM). Compound 5m expressed significant inhibitory activities and a higher COX-2 selectivity index (IC50 = 87.74 nM, SI = 2.05) in comparison with Indomethacin (SI = 0.52), with less selectivity than Celecoxib (SI = 8.31). Simulation docking studies were carried out to gain insights into the binding interaction of compounds 5h and 5m in the vicinity of COX-1 and COX-2 enzymes that illustrated the importance of pyrazole clubbed thiazole core in hydrogen bonding interactions. The thiazole motif of compounds 5h and 5m exhibited a well orientation toward COX-1 Arg120 key residue by hydrogen bonding interactions. Compound 5h revealed an additional arene-cation interaction with Arg120 that could rationalize its superior COX-1 inhibitory activity. Compounds 5h and 5m overlaid the co-crystallized ligand Celecoxib I differently in the active site of COX-2. Compound 5m showed an enhanced accommodation with binding energy of - 6.13 vs. - 1.70 kcal/mol of compounds 5h. The naphthalene ring of compound 5m adopted the Celecoxib I benzene sulfonamide region that is stabilized by hydrogen-arene interactions with the hydrophobic sidechains of the key residues Ser339 and Phe504. Further, the core structure of compound 5m, pyrazole clubbed thiazole, revealed deeper hydrophobic interactions with Ala513, Leu517 and Val509 residues. Finally, a sensitive and accurate UPLC-MS/MS method was developed for the simultaneous estimation of some selected promising pyrazole derivatives in rat plasma. Accordingly, compounds 5h and 5m were suggested to be promising potent analgesic and anti-inflammatory agents with improved safety profiles and a novel COX isozyme modulation activity.

Release of damaged mitochondrial DNA: A novel factor in stimulating inflammatory response

Mitochondrial DNA (mtDNA) is a circular double-stranded genome that exists independently of the nucleus. In recent years, research on mtDNA has significantly increased, leading to a gradual increase in understanding of its physiological and pathological characteristics. Reactive oxygen species (ROS) and other factors can damage mtDNA. This damaged mtDNA can escape from the mitochondria to the cytoplasm or extracellular space, subsequently activating immune signaling pathways, such as NLR family pyrin domain protein 3 (NLRP3), and triggering inflammatory responses. Numerous studies have demonstrated the involvement of mtDNA damage and leakage in the pathological mechanisms underlying various diseases including infectious diseases, metabolic inflammation, and immune disorders. Consequently, comprehensive investigation of mtDNA can elucidate the pathological mechanisms underlying numerous diseases. The prevention of mtDNA damage and leakage has emerged as a novel approach to disease treatment, and mtDNA has emerged as a promising target for drug development. This article provides a comprehensive review of the mechanisms underlying mtDNA-induced inflammation, its association with various diseases, and the methods used for its detection.

Mitochondrial DNA Leakage and cGas/STING Pathway in Microglia: Crosstalk Between Neuroinflammation and Neurodegeneration

Neurodegenerative diseases, characterized by abnormal deposition of misfolded proteins, often present with progressive loss of neurons. Chronic neuroinflammation is a striking hallmark of neurodegeneration. Microglia, as the primary immune cells in the brain, is the main type of cells that participate in the formation of inflammatory microenvironment. Cytoplasmic free mitochondrial DNA (mtDNA), a common component of damage-associated molecular patterns (DAMPs), can activate the cGas/stimulator of interferon genes (STING) signalling, which subsequently produces type I interferon and proinflammatory cytokines. There are various sources of free mtDNA in microglial cytoplasm, but mitochondrial oxidative stress accumulation plays the vital role. The upregulation of cGas/STING pathway in microglia contributes to the abnormal and persistent microglial activation, accompanied by excessive secretion of neurotoxic inflammatory mediators such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), which exacerbates the damage of neurons and promotes the development of neurodegeneration. Currently, novel therapeutic approaches need to be found to delay the progression of neurodegenerative disorders, and regulation of the cGas/STING signaling in microglia may be a potential target.

Consequences of Exposure to Hypobaric Hypoxia Associated with High Altitude on Spermatogenesis and Seminal Parameters: A Literature Review

Preclinical research has provided compelling evidence indicating that exposure to hypobaric hypoxia (HH) results in a deterioration of spermatogenesis. This adverse effect extends to the underlying molecular mechanisms, progressively leading to impairments in the seminiferous epithelium and germ cells and alterations in semen parameters. Indeed, several studies have demonstrated that animals exposed to HH, whether in natural high-altitude environments or under simulated hypoxic conditions, exhibit damage to the self-renewal and differentiation of spermatogenesis, an increase in germline cell apoptosis, and structural alterations in the seminiferous tubules. One of the primary mechanisms associated with the inhibition of differentiation and an increase in apoptosis among germ cells is an elevated level of oxidative stress, which has been closely associated with HH exposure. Human studies have shown that individuals exposed to HH, such as mountaineers and alpinists, exhibit decreased sperm count, reduced motility, diminished viability, and increased sperm with abnormal morphology in their semen. This evidence strongly suggests that exposure to HH may be considered a significant risk factor that could elevate the prevalence of male infertility. This literature review aims to provide a comprehensive description and propose potential mechanisms that could elucidate the infertility processes induced by HH. By doing so, it contributes to expanding our understanding of the challenges posed by extreme environments on human physiology, opening new avenues for research in this field.

Mitochondrial Targeted Interventions for Aging

Changes in mitochondrial function play a critical role in the basic biology of aging and age-related disease. Mitochondria are typically thought of in the context of ATP production and oxidant production. However, it is clear that the mitochondria sit at a nexus of cell signaling where they affect metabolite, redox, and energy status, which influence many factors that contribute to the biology of aging, including stress responses, proteostasis, epigenetics, and inflammation. This has led to growing interest in identifying mitochondrial targeted interventions to delay or reverse age-related decline in function and promote healthy aging. In this review, we discuss the diverse roles of mitochondria in the cell. We then highlight some of the most promising strategies and compounds to target aging mitochondria in preclinical testing. Finally, we review the strategies and compounds that have advanced to clinical trials to test their ability to improve health in older adults.

Mitochondrial ribosomal protein L12 potentiates hepatocellular carcinoma by regulating mitochondrial biogenesis and metabolic reprogramming

BACKGROUND

Mitochondrial dysfunction and metabolic reprogramming are key features of hepatocellular carcinoma (HCC). Despite its significance, the precise underlying mechanism behind these processes has not been fully elucidated. The latest investigations, along with our previous discoveries, have substantiated the significant role of mitochondrial ribosomal protein L12 (MRPL12), a newly identified gene involved in mitochondrial transcription regulation, in the modulation of mitochondrial metabolism. Nevertheless, the role of MRPL12 in tumorigenesis has yet to be investigated.

METHODS

The expression of MRPL12 in HCC was assessed using an online database. Western blot, quantitative real-time polymerase chain reaction (qRT-PCR), and immunohistochemistry (IHC) were employed to determine the expression of MRPL12 in HCC tissues, patient-derived organoid (PDO), and cell lines. The correlation between MRPL12 expression and clinicopathological features, as well as prognosis, was examined using tissue microarray analysis. An in vivo subcutaneous tumor xenograft model, gene knockdown or overexpression assay, chromatin immunoprecipitation (ChIP) assay, Seahorse XF96 assay, and cell function assay were employed to investigate the biological function and potential molecular mechanism of MRPL12 in HCC.

RESULTS

A significant upregulation of MRPL12 was observed in HCC cells, PDO and patient tissues, which correlated with advanced tumor stage, higher grade and poor prognosis. MRPL12 overexpression promoted cell proliferation, migration, and invasion in vitro, as well as tumorigenicity in vivo, whereas MRPL12 knockdown showed the opposite effect. MRPL12 knockdown also inhibited the capacity of organoids proliferation capacity. Furthermore, MRPL12 was found to be crucial for maintaining mitochondrial homeostasis. Both gain and loss-of-function experiments targeting MRPL12 in HCC cells altered oxidative phosphorylation (OXPHOS) and mitochondrial DNA content. Notably, suppression of OXPHOS effectively mitigates the tumor-promoting effect attributed to MRPL12 overexpression, implying the involvement of MRPL12 in HCC through the modulation of mitochondrial metabolism. Besides, Yin Yang 1 (YY1) was identified as a transcription factor responsible for regulating MRPL12, while the PI3K/mTOR pathway was found to act as an upstream regulator of YY1. MRPL12 knockdown attenuated the YY1 overexpression or PI3K/mTOR activation-induced malignant phenotype in HCC cells.

CONCLUSION

Our findings provide compelling evidence that MRPL12 is implicated in driving the malignant phenotype of HCC via regulating mitochondrial metabolism. Moreover, the aberrant expression of MRPL12 in HCC is mediated by the upstream PI3K/mTOR/YY1 pathway. These results highlight the potential of targeting MRPL12 as a promising therapeutic strategy for the treatment of HCC.

Molecular marker identification, antioxidant, antinociceptive, and anti-inflammatory responsiveness of malonic acid capped silver nanoparticle

Nano-sized silver has drawn a great deal of attention in the field of health sciences owing to its remarkable therapeutic applications. Interestingly, the method applied to synthesize nanoparticles and the choice of reagents considerably influence their therapeutic potential and toxicities. Current research has explored the toxicity, anti-inflammatory, antinociceptive, and antioxidant responses of the malonic acid-capped silver nanoparticles (MA-AgNPs (C) by using sodium borohydride as a reducing agent at low temperatures by employing both in vitro and in vivo approaches. Furthermore, it has highlighted the synergistic effect of these novel compounds with conventional anti-inflammatory therapeutic agents. Acute and sub-acute toxicity analysis performed following OECD guidelines showed that the studied MA-AgNPs (C) are safer, and prominent toxic signs have not been detected at the highest studied dose of 2,000 mg/kg. Cytotoxicity evaluation through brine shrimp lethality revealed 20% lethality at the highest concentration of 169.8 μg/mL. Significantly, positive anti-inflammatory and analgesic responses alone as well as synergism with the standard were identified through in vitro as well as in vivo methods which were more potent at a lower dose (200 mg/kg). Notably synergistic outcomes were more pronounced than individual ones, indicating their prominent effect as a feasible drug delivery system. IL-6 and TNF-α assessment in excised paw tissue through RTPCR technique further supported their anti-inflammatory potential. DPPH assay revealed eminent in vitro antioxidant activity which was further corroborated by in vivo antioxidant assessment through evaluation of SOD in excised paw tissue.

Mitochondrial Quality Control: Its Role in Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease, is characterized by hepatic steatosis and metabolic dysfunction and is often associated with obesity and insulin resistance. Recent research indicates a rapid escalation in MASLD cases, with projections suggesting a doubling in the United States by 2030. This review focuses on the central role of mitochondria in the pathogenesis of MASLD and explores potential therapeutic interventions. Mitochondria are dynamic organelles that orchestrate hepatic energy production and metabolism and are critically involved in MASLD. Dysfunctional mitochondria contribute to lipid accumulation, inflammation, and liver fibrosis. Genetic associations further underscore the relationship between mitochondrial dynamics and MASLD susceptibility. Although U.S. Food and Drug Administration-approved treatments for MASLD remain elusive, ongoing clinical trials have highlighted promising strategies that target mitochondrial dysfunction, including vitamin E, metformin, and glucagon-like peptide-1 receptor agonists. In preclinical studies, novel therapeutics, including nicotinamide adenine dinucleotide+ precursors, urolithin A, spermidine, and mitoquinone, have shown beneficial effects, such as improving mitochondrial quality control, reducing oxidative stress, and ameliorating hepatic steatosis and inflammation. In conclusion, mitochondrial dysfunction is central to MASLD pathogenesis. The innovative mitochondria-targeted approaches discussed in this review offer a promising avenue for reducing the burden of MASLD and improving global quality of life.

Nutritional significance and promising therapeutic/medicinal application of camel milk as a functional food in human and animals: a comprehensive review

Camel milk (CM) is the key component of human diet specially for the population belongs to the arid and semi-arid regions of the world. CM possess unique composition as compare to the cow milk with abundant amount of medium chain fatty acids in fat low lactose and higher concentration of whey protein and vitamin C. Besides the nutritional significance of CM, it also contains higher concentration of bioactive compounds including bioactive peptides, lactic acid bacteria (LAB), lactoferrin (LF), lactoperoxidase, lysozyme casein and immunoglobulin. Recently, CM and their bioactive compounds gaining more attention toward scientific community owing to their multiple health benefits, especially in the current era of emerging drug resistance and untold side effects of synthetic medicines. Consumption of fresh or fermented CM and its products presumed exceptional nutraceutical and medicinal properties, including antimicrobial, anti-inflammatory, antioxidant, anti-diabetic, hepatoprotective, nephroprotective, anticancer and immunomodulatory activities. Moreover, CM isolated LAB exhibit antioxidant and probiotic effects leading to enhance the innate and adaptive immune response against both gram-negative and gram-positive pathogenic bacteria. The main objective of this review is to highlight the nutritional significance, pharmaceutical potential, medicinal value and salient beneficial health aspect of CM for human and animals.

Mitochondrial DNA copy number in Hepatitis C virus-related chronic liver disease: impact of direct-acting antiviral therapy

Hepatitis C virus (HCV) infection can regulate the number and dynamics of mitochondria, and is associated with a prominent hepatic mitochondrial injury. Mitochondrial distress conveys oxidative damage which is implicated in liver disease progression. The present study was conducted to assess the change of mitochondrial DNA (mtDNA) copy number in patients with HCV-related chronic liver disease and the impact of direct-acting antiviral (DAA) therapy. Whole blood mtDNA copy number was measured using real-time quantitative polymerase chain reaction at baseline and 12 weeks after the end of therapy in 50 treatment-naïve HCV-infected patients who achieved sustained viral response (SVR) after DAA therapy and 20 healthy controls. Whole blood mtDNA copy number appeared significantly lower in HCV-infected patients before therapy compared to healthy subjects (P < 0.001). Post-treatment, there was significant increase of mtDNA copy number in HCV-infected patients at SVR12 compared to the pre-treatment values (P < 0.001), meanwhile it didn't differ significantly between HCV-infected patients after therapy and healthy subjects (P = 0.059). Whole blood mtDNA copy number correlated inversely to the serum bilirubin in HCV-infected patients (P = 0.013), however it didn't correlate significantly to the serum aminotransferases, viral load or fibrosis-4 score (P > 0.05). In conclusion, chronic HCV infection has been associated with a prominent mitochondrial injury which could mediate a progressive liver disease. The improved mtDNA content after DAA therapy highlights a possible potential of these drugs to alleviate mitochondrial damage in HCV-related liver disease.

Characterizing Early Cardiac Metabolic Programming via 30% Maternal Nutrient Reduction during Fetal Development in a Non-Human Primate Model

Intra-uterine growth restriction (IUGR) is a common cause of fetal/neonatal morbidity and mortality and is associated with increased offspring predisposition for cardiovascular disease (CVD) development. Mitochondria are essential organelles in maintaining cardiac function, and thus, fetal cardiac mitochondria could be responsive to the IUGR environment. In this study, we investigated whether in utero fetal cardiac mitochondrial programming can be detectable in an early stage of IUGR pregnancy. Using a well-established nonhuman IUGR primate model, we induced IUGR by reducing by 30% the maternal diet (MNR), both in males (MNR-M) and in female (MNR-F) fetuses. Fetal cardiac left ventricle (LV) tissue and blood were collected at 90 days of gestation (0.5 gestation, 0.5 G). Blood biochemical parameters were determined and heart LV mitochondrial biology assessed. MNR fetus biochemical blood parameters confirm an early fetal response to MNR. In addition, we show that in utero cardiac mitochondrial MNR adaptations are already detectable at this early stage, in a sex-divergent way. MNR induced alterations in the cardiac gene expression of oxidative phosphorylation (OXPHOS) subunits (mostly for complex-I, III, and ATP synthase), along with increased protein content for complex-I, -III, and -IV subunits only for MNR-M in comparison with male controls, highlight the fetal cardiac sex-divergent response to MNR. At this fetal stage, no major alterations were detected in mitochondrial DNA copy number nor markers for oxidative stress. This study shows that in 90-day nonhuman primate fetuses, a 30% decrease in maternal nutrition generated early in utero adaptations in fetal blood biochemical parameters and sex-specific alterations in cardiac left ventricle gene and protein expression profiles, affecting predominantly OXPHOS subunits. Since the OXPHOS system is determinant for energy production in mitochondria, our findings suggest that these early IUGR-induced mitochondrial adaptations play a role in offspring's mitochondrial dysfunction and can increase predisposition to CVD in a sex-specific way.

Anti-inflammatory effect of 3-fluorophenyl pyrimidinylimidazo[2,1-b]thiazole derivatives as p38α inhibitors

In the present work, the anti-inflammatory effect of 30 compounds containing 3-fluorophenyl pyrimidinylimidazo[2,1-b]thiazole was investigated. All final target compounds showed significant Inhibitory effect on p38α. P38α is considered one of the key kinases in the inflammatory process due to its regulatory effect on pro-inflammatory mediators. The final target compounds divided into four group based on the type of terminal moiety (amide and sulfonamide) and the linker between pyrimidine ring and terminal moiety (ethyl and propyl). Most compounds with terminal sulfonamide moiety and propyl linker between the sulfonamide and pyrimidine ring were the most potent among all synthesized final target compounds with sub-micromolar IC50s. Compound 24g (with p-Cl benzene sulfonamide and propyl linker) exhibited the highest activity over P38α with IC50 0.68 µM. All final target compounds were tested for their ability to inhibit nitric oxide release and prostaglandin E2 production. Compounds having amide terminal moiety with ethyl linker showed higher inhibitory activity for nitric oxide release and compound 21d exhibited the highest activity for nitric oxide release with IC50 1.21 µM. Compounds with terminal sulfonamide moiety and propyl linker showed the highest activity for inhibiting PGE2 production and compounds 24i and 24g had the lowest IC50s with value 0.87 and 0.89 µM, respectively. Compounds 21d, 22d and 24g were tested for their ability to inhibit over expression of iNOS, COX1, and COX2. In addition the ability of compounds 21d, 22d and 24g to inhibit inflammatory cytokines were determined. Finally molecular docking of the three compounds were performed on P38α crystal structure to expect their mode of binding.

In Vitro Antioxidant and Inhibitory Study of Picrorhiza kurroa (Kutki), Syzygium aromaticum (Loung), Lawsonia inermis (Henna), Rheum emodi (Revand Chini), Curcuma longa (Haldi) Against Lipid Per-Oxidation in Mice Brain and Liver

The aerobic organisms not only need oxygen for survival, but oxygen is also fundamentally malignant to the aerobic organism on the grounds of free radical generation and their affiliation with free oxidative stress. This study was done to evaluate the antioxidant and protective properties of P kurroa, S aromaticum, L inermis, R emodi, and C longa against lipid peroxidation induced by different pro-oxidants. The aqueous extracts of these medicinal plants showed inhibition against thiobarbituric acid reactive species (TBARS) induced by different pro-oxidants (10 mM FeSO4 and 5 mM sodium nitroprusside) in the brain and liver of mice. Moreover, the free radical scavenging activities of the extracts were evaluated by the scavenging of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. L inermis, S aromaticum, and R emodi showed higher inhibitory effects, which could be attributed to their significantly reduced ability and free radical scavenging activities. Therefore, the oxidative stress in the brain and liver could be potentially managed or prevented by the dietary intake of L inermis, S aromaticum, and R emodi plants, which justifies the use of these plants in various degenerative diseases. C longa and P kurroa showed relatively weak antioxidant activities.

The role of mtDAMPs in the trauma-induced systemic inflammatory response syndrome

Systemic inflammatory response syndrome (SIRS) is a non-specific exaggerated defense response caused by infectious or non-infectious stressors such as trauma, burn, surgery, ischemia and reperfusion, and malignancy, which can eventually lead to an uncontrolled inflammatory response. In addition to the early mortality due to the "first hits" after trauma, the trauma-induced SIRS and multiple organ dysfunction syndrome (MODS) are the main reasons for the poor prognosis of trauma patients as "second hits". Unlike infection-induced SIRS caused by pathogen-associated molecular patterns (PAMPs), trauma-induced SIRS is mainly mediated by damage-associated molecular patterns (DAMPs) including mitochondrial DAMPs (mtDAMPs). MtDAMPs released after trauma-induced mitochondrial injury, including mitochondrial DNA (mtDNA) and mitochondrial formyl peptides (mtFPs), can activate inflammatory response through multiple inflammatory signaling pathways. This review summarizes the role and mechanism of mtDAMPs in the occurrence and development of trauma-induced SIRS.

Glaucomatous optic neuropathy: Mitochondrial dynamics, dysfunction and protection in retinal ganglion cells

Glaucoma is a leading cause of irreversible blindness worldwide and is characterized by a slow, progressive, and multifactorial degeneration of retinal ganglion cells (RGCs) and their axons, resulting in vision loss. Despite its high prevalence in individuals 60 years of age and older, the causing factors contributing to glaucoma progression are currently not well characterized. Intraocular pressure (IOP) is the only proven treatable risk factor. However, lowering IOP is insufficient for preventing disease progression. One of the significant interests in glaucoma pathogenesis is understanding the structural and functional impairment of mitochondria in RGCs and their axons and synapses. Glaucomatous risk factors such as IOP elevation, aging, genetic variation, neuroinflammation, neurotrophic factor deprivation, and vascular dysregulation, are potential inducers for mitochondrial dysfunction in glaucoma. Because oxidative phosphorylation stress-mediated mitochondrial dysfunction is associated with structural and functional impairment of mitochondria in glaucomatous RGCs, understanding the underlying mechanisms and relationship between structural and functional alterations in mitochondria would be beneficial to developing mitochondria-related neuroprotection in RGCs and their axons and synapses against glaucomatous neurodegeneration. Here, we review the current studies focusing on mitochondrial dynamics-based structural and functional alterations in the mitochondria of glaucomatous RGCs and therapeutic strategies to protect RGCs against glaucomatous neurodegeneration.

Experimental animal models of chronic inflammation

Inflammation is a general term for a wide variety of both physiological and pathophysiological processes in the body which primarily prevents the body from diseases and helps to remove dead tissues. It has a crucial part in the body immune system. Tissue damage can recruit inflammatory cells and cytokines and induce inflammation. Inflammation can be classified as acute, sub-acute, and chronic. If it remained unresolved and lasted for prolonged periods, it would be considered as chronic inflammation (CI), which consequently exacerbates tissue damage in different organs. CI is the main pathophysiological cause of many disorders such as obesity, diabetes, arthritis, myocardial infarction, and cancer. Thus, it is critical to investigate different mechanisms involved in CI to understand its processes and to find proper anti-inflammatory therapeutic approaches for it. Animal models are one of the most useful tools for study about different diseases and mechanisms in the body, and are important in pharmacological studies to find proper treatments. In this study, we discussed the various experimental animal models that have been used to recreate CI which can help us to enhance the understanding of CI mechanisms in human and contribute to the development of potent new therapies.

Mitochondrial Cholesterol Metabolites in a Bile Acid Synthetic Pathway Drive Nonalcoholic Fatty Liver Disease: A Revised "Two-Hit" Hypothesis

The rising prevalence of nonalcoholic fatty liver disease (NAFLD)-related cirrhosis highlights the need for a better understanding of the molecular mechanisms responsible for driving the transition of hepatic steatosis (fatty liver; NAFL) to steatohepatitis (NASH) and fibrosis/cirrhosis. Obesity-related insulin resistance (IR) is a well-known hallmark of early NAFLD progression, yet the mechanism linking aberrant insulin signaling to hepatocyte inflammation has remained unclear. Recently, as a function of more distinctly defining the regulation of mechanistic pathways, hepatocyte toxicity as mediated by hepatic free cholesterol and its metabolites has emerged as fundamental to the subsequent necroinflammation/fibrosis characteristics of NASH. More specifically, aberrant hepatocyte insulin signaling, as found with IR, leads to dysregulation in bile acid biosynthetic pathways with the subsequent intracellular accumulation of mitochondrial CYP27A1-derived cholesterol metabolites, (25R)26-hydroxycholesterol and 3β-Hydroxy-5-cholesten-(25R)26-oic acid, which appear to be responsible for driving hepatocyte toxicity. These findings bring forth a "two-hit" interpretation as to how NAFL progresses to NAFLD: abnormal hepatocyte insulin signaling, as occurs with IR, develops as a "first hit" that sequentially drives the accumulation of toxic CYP27A1-driven cholesterol metabolites as the "second hit". In the following review, we examine the mechanistic pathway by which mitochondria-derived cholesterol metabolites drive the development of NASH. Insights into mechanistic approaches for effective NASH intervention are provided.

The effect of ginsenosides on liver injury in preclinical studies: a systematic review and meta-analysis

Background: Liver injury is a severe liver lesion caused by various etiologies and is one of the main areas of medical research. Panax ginseng C.A. Meyer has traditionally been used as medicine to treat diseases and regulate body functions. Ginsenosides are the main active components of ginseng, and their effects on liver injury have been extensively reported. Methods: Preclinical studies meeting the inclusion criteria were retrieved from PubMed, Web of Science, Embase, China National Knowledge Infrastructure (CNKI), and Wan Fang Data Knowledge Service Platforms. The Stata 17.0 was used to perform the meta-analysis, meta-regression, and subgroup analysis. Results: This meta-analysis included ginsenosides Rb1, Rg1, Rg3, and compound K (CK), in 43 articles. The overall results showed that multiple ginsenosides significantly reduced alanine aminotransferase (ALT) and aspartate aminotransferase (AST), affected oxidative stress-related indicators, such as superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GSH-Px), and catalase (CAT), and reduced levels of inflammatory factor, such as factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6). Additionally, there was a large amount of heterogeneity in the meta-analysis results. Our predefined subgroup analysis shows that the animal species, the type of liver injury model, the duration of treatment, and the administration route may be the sources of some of the heterogeneity. Conclusion: In a word, ginsenosides have good efficacy against liver injury, and their potential mechanisms of action target antioxidant, anti-inflammatory and apoptotic-related pathways. However, the overall methodological quality of our current included studies was low, and more high-quality studies are needed to confirm their effects and mechanisms further.

Intracellular DAMPs in Neurodegeneration and Their Role in Clinical Therapeutics

Neuroinflammation is the major implication of neurodegeneration. This is a complex process which initiates from the cellular injury triggering the innate immune system which gives rise to damage-associated molecular patterns (DAMPs) which are also recognized as endogenous danger indicators. These originate from various compartments of the cell under pathological stimulus. These are very popular candidates having their origin in the intracellular compartments and organelles of the cell and may have their site of action itself in the intracellular or at the extracellular spaces. Under the influence of the pathological stimuli, they interact with the pattern-recognition receptor to initiate their pro-inflammatory cascade followed by the cytokine release. This provides a good opportunity for diagnostic and therapeutic interventions creating better conditions for repair and reversal. Since the major contributors arise from the intracellular compartment, in this review, we have attempted to focus on the DAMP molecules arising from the intracellular compartments and their specific roles in the neurodegenerative events explaining their downstream mediators and signaling. Moreover, we have tried to cover the latest interventions in terms of DAMPs as clinical biomarkers which can assist in detecting the disease and also target it to reduce the innate-immune activation response which can help in reducing the sterile neuroinflammation having an integral role in the neurodegenerative processes.

Endogenous DNase Activity in an Animal Model of Acute Liver Failure

Deoxyribonucleases (DNases) cleave extracellular DNA (ecDNA) and are under intense research as interventions for diseases associated with high ecDNA, such as acute live injury. DNase I treatment decreases morbidity and mortality in this animal model. Endogenous DNase activity has high interindividual variability. In this study, we tested the hypothesis that high endogenous DNase activity is beneficial in an animal model of acute liver failure. DNase activity was measured in the plasma of adult male mice taken before i.p. injection of thioacetamide to induce acute liver failure. The survival of mice was monitored for 48 h. Mice were retrospectively divided into two groups based on the median DNase activity assessed using the gel-based single-radial enzyme diffusion assay. In acute liver failure, mice with a higher baseline DNase activity had lower mortality after 48 h (by 25%). Different protection of ecDNA against nucleases by vesicles or DNA-binding proteins could play a role and should be further evaluated. Similarly, the role of endogenous DNase activity should be analyzed in other disease models associated with high ecDNA.

Multifaceted roles of aerobic glycolysis and oxidative phosphorylation in hepatocellular carcinoma

Liver cancer is a common malignancy with high morbidity and mortality rates. Changes in liver metabolism are key factors in the development of primary hepatic carcinoma, and mitochondrial dysfunction is closely related to the occurrence and development of tumours. Accordingly, the study of the metabolic mechanism of mitochondria in primary hepatic carcinomas has gained increasing attention. A growing body of research suggests that defects in mitochondrial respiration are not generally responsible for aerobic glycolysis, nor are they typically selected during tumour evolution. Conversely, the dysfunction of mitochondrial oxidative phosphorylation (OXPHOS) may promote the proliferation, metastasis, and invasion of primary hepatic carcinoma. This review presents the current paradigm of the roles of aerobic glycolysis and OXPHOS in the occurrence and development of hepatocellular carcinoma (HCC). Mitochondrial OXPHOS and cytoplasmic glycolysis cooperate to maintain the energy balance in HCC cells. Our study provides evidence for the targeting of mitochondrial metabolism as a potential therapy for HCC.

Prolonged hypernutrition impairs TREM2-dependent efferocytosis to license chronic liver inflammation and NASH development

Obesity-induced chronic liver inflammation is a hallmark of nonalcoholic steatohepatitis (NASH)-an aggressive form of nonalcoholic fatty liver disease. However, it remains unclear how such a low-grade, yet persistent, inflammation is sustained in the liver. Here, we show that the macrophage phagocytic receptor TREM2, induced by hepatocyte-derived sphingosine-1-phosphate, was required for efferocytosis of lipid-laden apoptotic hepatocytes and thereby maintained liver immune homeostasis. However, prolonged hypernutrition led to the production of proinflammatory cytokines TNF and IL-1β in the liver to induce TREM2 shedding through ADAM17-dependent proteolytic cleavage. Loss of TREM2 resulted in aberrant accumulation of dying hepatocytes, thereby further augmenting proinflammatory cytokine production. This ultimately precipitated a vicious cycle that licensed chronic inflammation to drive simple steatosis transition to NASH. Therefore, impaired macrophage efferocytosis is a previously unrecognized key pathogenic event that enables chronic liver inflammation in obesity. Blocking TREM2 cleavage to restore efferocytosis may represent an effective strategy to treat NASH.

Epigenetics and mitochondrial dysfunction insights into the impact of the progression of non-alcoholic fatty liver disease

A metabolic problem occurs when regular functions of the body are disrupted due to an undesirable imbalance. Nonalcoholic fatty liver disease (NAFLD) is considered as one of the most common in this category. NAFLD is subclassified and progresses from lipid accumulation to cirrhosis before advancing to hepatocellular cancer. In spite of being a critical concern, the standard treatment is inadequate. Metformin, silymarin, and other nonspecific medications are used in the management of NAFLD. Aside from this available medicine, maintaining a healthy lifestyle has been emphasized as a means of combating this. Epigenetics, which has been attributed to NAFLD, is another essential feature of this disease that has emerged as a result of several sorts of research. The mechanisms by which DNA methylation, noncoding RNA, and histone modification promote NAFLD have been extensively researched. Another organelle, mitochondria, which play a pivotal role in biological processes, contributes to the global threat. Individuals with NAFLD have been documented to have a multitude of alterations and malfunctioning. Mitochondria are mainly concerned with the process of energy production and regulation of the signaling pathway on which the fate of a cell relies. Modulation of mitochondria leads to elevated lipid deposition in the liver. Further, changes in oxidation states result in an impaired balance between the antioxidant system and reactive oxygen species directly linked to mitochondria. Hence mitochondria have a definite role in potentiating NAFLD. In this regard, it is essential to consider the role of epigenetics as well as mitochondrial contribution while developing a medication or therapy with the desired accuracy.

Roles of Mitochondrial DNA Damage in Kidney Diseases: A New Biomarker

The kidney is a mitochondria-rich organ, and kidney diseases are recognized as mitochondria-related pathologies. Intact mitochondrial DNA (mtDNA) maintains normal mitochondrial function. Mitochondrial dysfunction caused by mtDNA damage, including impaired mtDNA replication, mtDNA mutation, mtDNA leakage, and mtDNA methylation, is involved in the progression of kidney diseases. Herein, we review the roles of mtDNA damage in different setting of kidney diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD). In a variety of kidney diseases, mtDNA damage is closely associated with loss of kidney function. The level of mtDNA in peripheral serum and urine also reflects the status of kidney injury. Alleviating mtDNA damage can promote the recovery of mitochondrial function by exogenous drug treatment and thus reduce kidney injury. In short, we conclude that mtDNA damage may serve as a novel biomarker for assessing kidney injury in different causes of renal dysfunction, which provides a new theoretical basis for mtDNA-targeted intervention as a therapeutic option for kidney diseases.

Characterization of Mitochondrial Alterations in Aicardi-Goutières Patients Mutated in RNASEH2A and RNASEH2B Genes

Aicardi-Goutières syndrome (AGS) is a rare encephalopathy characterized by neurological and immunological features. Mitochondrial dysfunctions may lead to mitochondrial DNA (mtDNA) release and consequent immune system activation. We investigated the role of mitochondria and mtDNA in AGS pathogenesis by studying patients mutated in RNASEH2B and RNASEH2A genes. Lymphoblastoid cell lines (LCLs) from RNASEH2A- and RNASEH2B-mutated patients and healthy control were used. Transmission Electron Microscopy (TEM) and flow cytometry were used to assess morphological alterations, reactive oxygen species (ROS) production and mitochondrial membrane potential variations. Seahorse Analyzer was used to investigate metabolic alterations, and mtDNA oxidation and VDAC1 oligomerization were assessed by immunofluorescence. Western blot and RT-qPCR were used to quantify mtTFA protein and mtDNA release. Morphological alterations of mitochondria were observed in both mutated LCLs, and loss of physiological membrane potential was mainly identified in RNASEH2A LCLs. ROS production and 8-oxoGuanine levels were increased in RNASEH2B LCLs. Additionally, the VDAC1 signal was increased, suggesting a mitochondrial pore formation possibly determining mtDNA release. Indeed, higher cytoplasmic mtDNA levels were found in RNASEH2B LCLs. Metabolic alterations confirmed mitochondrial damage in both LCLs. Data highlighted mitochondrial alterations in AGS patients' LCLs suggesting a pivotal role in AGS pathogenesis.

Involvement of oxidative species in cyclosporine-mediated cholestasis

Cyclosporine is an established medication for the prevention of transplant rejection. However, adverse consequences such as nephrotoxicity, hepatotoxicity, and cholestasis have been associated with prolonged usage. In cyclosporine-induced obstructive and chronic cholestasis, for example, the overproduction of oxidative stress is significantly increased. Additionally, cyclosporine exerts adverse effects on liver function and redox balance responses in treated rats, as evidenced by its increasing levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and bilirubin while also decreasing the levels of glutathione and NADPH. Cyclosporine binds to cyclophilin to produce its therapeutic effects, and the resulting complex inhibits calcineurin, causing calcium to accumulate in the mitochondria. Accumulating calcium with concomitant mitochondrial abnormalities induces oxidative stress, perturbation in ATP balance, and failure of calcium pumps. Also, cyclosporine-induced phagocyte oxidative stress generation via the interaction of phagocytes with Toll-like receptor-4 has been studied. The adverse effect of cyclosporine may be amplified by the release of mitochondrial DNA, mediated by oxidative stress-induced mitochondrial damage. Given the uncertainty surrounding the mechanism of cyclosporine-induced oxidative stress in cholestasis, we aim to illuminate the involvement of oxidative stress in cyclosporine-mediated cholestasis and also explore possible strategic interventions that may be applied in the future.

Loss of Sam50 in hepatocytes induces cardiolipin-dependent mitochondrial membrane remodeling to trigger mtDNA release and liver injury

BACKGROUND AND AIMS

Sam50, a key component of the sorting and assembly machinery (SAM) complex, is also involved in bridging mitochondrial outer-membrane and inner-membrane contacts. However, the physiological and pathological functions of Sam50 remain largely unknown.

APPROACH AND RESULTS

Here we show that Sam50 interacts with MICOS (mitochondrial contact site and cristae organizing system) and ATAD3 (ATPase family AAA domain-containing protein 3) to form the Sam50-MICOS-ATAD3-mtDNA axis, which maintains mtDNA stability. Loss of Sam50 causes mitochondrial DNA (mtDNA) aggregation. Furthermore, Sam50 cooperates with Mic60 to bind to cardiolipin, maintaining the integrity of mitochondrial membranes. Sam50 depletion leads to cardiolipin externalization, which causes mitochondrial outer-membrane and inner-membrane (including crista membrane) remodeling, triggering Bax mitochondrial recruitment, mtDNA aggregation, and release. Physiologically, acetaminophen (an effective antipyretic and analgesic)-caused Sam50 reduction or Sam50 liver-specific knockout induces mtDNA release, leading to activation of the cGAS-STING pathway and liver inflammation in mice. Moreover, exogenous expression of Sam50 remarkably attenuates APAP-induced liver hepatoxicity.

CONCLUSIONS

Our findings uncover the critical role of Sam50 in maintaining mitochondrial membrane integrity and mtDNA stability in hepatocytes and reveal that Sam50 depletion-induced cardiolipin externalization is a signal of mtDNA release and controls mtDNA-dependent innate immunity.

Mitochondrial-derived damage-associated molecular patterns amplify neuroinflammation in neurodegenerative diseases

Both mitochondrial dysfunction and neuroinflammation are implicated in neurodegeneration and neurodegenerative diseases. Accumulating evidence shows multiple links between mitochondrial dysfunction and neuroinflammation. Mitochondrial-derived damage-associated molecular patterns (DAMPs) are recognized by immune receptors of microglia and aggravate neuroinflammation. On the other hand, inflammatory factors released by activated glial cells trigger an intracellular cascade, which regulates mitochondrial metabolism and function. The crosstalk between mitochondrial dysfunction and neuroinflammatory activation is a complex and dynamic process. There is strong evidence that mitochondrial dysfunction precedes neuroinflammation during the progression of diseases. Thus, an in-depth understanding of the specific molecular mechanisms associated with mitochondrial dysfunction and the progression of neuroinflammation in neurodegenerative diseases may contribute to the identification of new targets for the treatment of diseases. In this review, we describe in detail the DAMPs that induce or aggravate neuroinflammation in neurodegenerative diseases including mtDNA, mitochondrial unfolded protein response (mtUPR), mitochondrial reactive oxygen species (mtROS), adenosine triphosphate (ATP), transcription factor A mitochondria (TFAM), cardiolipin, cytochrome c, mitochondrial Ca2+ and iron.

Hepatitis B x (HBx) as a Component of a Functional Cure for Chronic Hepatitis B

Patients who are carriers of the hepatitis B virus (HBV) are at high risk of chronic liver disease (CLD) which proceeds from hepatitis, to fibrosis, cirrhosis and to hepatocellular carcinoma (HCC). The hepatitis B-encoded X antigen, HBx, promotes virus gene expression and replication, protects infected hepatocytes from immunological destruction, and promotes the development of CLD and HCC. For virus replication, HBx regulates covalently closed circular (ccc) HBV DNA transcription, while for CLD, HBx triggers cellular oxidative stress, in part, by triggering mitochondrial damage that stimulates innate immunity. Constitutive activation of NF-κB by HBx transcriptionally activates pro-inflammatory genes, resulting in hepatocellular destruction, regeneration, and increased integration of the HBx gene into the host genome. NF-κB is also hepatoprotective, which sustains the survival of infected cells. Multiple therapeutic approaches include direct-acting anti-viral compounds and immune-stimulating drugs, but functional cures were not achieved, in part, because none were yet devised to target HBx. In addition, many patients with cirrhosis or HCC have little or no virus replication, but continue to express HBx from integrated templates, suggesting that HBx contributes to the pathogenesis of CLD. Blocking HBx activity will, therefore, impact multiple aspects of the host–virus relationship that are relevant to achieving a functional cure.

The Immune Pathogenesis of Acute-On-Chronic Liver Failure and the Danger Hypothesis

Acute-on-chronic liver failure (ACLF) is a group of clinical syndromes related to severe acute liver function impairment and multiple-organ failure caused by various acute triggering factors on the basis of chronic liver disease. Due to its severe condition, rapid progression, and high mortality, it has received increasing attention. Recent studies have shown that the pathogenesis of ACLF mainly includes direct injury and immune injury. In immune injury, cytotoxic T lymphocytes (CTLs), dendritic cells (DCs), and CD4⁺ T cells accumulate in the liver tissue, secrete a variety of proinflammatory cytokines and chemokines, and recruit more immune cells to the liver, resulting in immune damage to the liver tissue, massive hepatocyte necrosis, and liver failure, but the key molecules and signaling pathways remain unclear. The “danger hypothesis” holds that in addition to the need for antigens, damage-associated molecular patterns (DAMPs) also play a very important role in the occurrence of the immune response, and this hypothesis is related to the pathogenesis of ACLF. Here, the research status and development trend of ACLF, as well as the mechanism of action and research progress on various DAMPs in ACLF, are summarized to identify biomarkers that can predict the occurrence and development of diseases or the prognosis of patients at an early stage.

Mitochondrial Dysfunction and Chronic Liver Disease

Mitochondria are generally considered the powerhouse of the cell, a small subcellular organelle that produces most of the cellular energy in the form of adenosine triphosphate (ATP). In addition, mitochondria are involved in various biological functions, such as biosynthesis, lipid metabolism, oxidative phosphorylation, cell signal transduction, and apoptosis. Mitochondrial dysfunction is manifested in different aspects, like increased mitochondrial reactive oxygen species (ROS), mitochondrial DNA (mtDNA) damage, adenosine triphosphate (ATP) synthesis disorder, abnormal mitophagy, as well as changes in mitochondrial morphology and structure. Mitochondrial dysfunction is related to the occurrence and development of various chronic liver diseases, including hepatocellular carcinoma (HCC), viral hepatitis, drug-induced liver injury (DILI), alcoholic fatty liver (AFL), and non-alcoholic fatty liver (NAFL). In this review, we summarize and discuss the role and mechanisms of mitochondrial dysfunction in chronic liver disease, focusing on and discussing some of the latest studies on mitochondria and chronic liver disease.

Design, Synthesis, and Anti-Inflammatory Activity of Some Coumarin Schiff Base Derivatives: In silico and in vitro Study

Introduction

Inflammation is a fundamental response of the immune system during tissue damage or pathogen infection to protect and maintain tissue homeostasis. However, inflammation may lead to life-threatening conditions. The most common treatment of inflammation is non-steroidal anti-inflammatory drugs (NSAIDs). Nowadays, the development of safer new NSAIDs is critical as most of the existing NSAIDs have serious adverse effects, such as gastrointestinal (GI) toxicity and cardiotoxicity. In the present study, four compounds as Schiff base derivatives of 7-hydroxy-4-formyl coumarin and 7-methoxy-4-formyl coumarin were designed and synthesized aiming to develop a lead compound that exhibits anti-inflammatory activity and circumvents the side effects of NSAIDs, especially GI toxicity.

Materials and Methods

Lipinski’s rule of five was applied for each designed molecule to evaluate the drug-likeness properties. Molecular docking studies were performed using the ligands and the cyclooxygenase-2 (COX-2) protein to select the best-scored molecule using AutoDock 4.2.6. The molecules were then synthesized and characterized. An in vitro anti-inflammatory assay of the compounds against the COX-2 receptor was realized through a protein denaturation assay.

Results and Discussion

All four synthesized ligands passed Lipinski’s rule of five and exhibited higher binding free energy compared to the positive standard control (ibuprofen), and the Ki values of compounds 5, 7, and 8 were in the nanomolar range. However, only compounds 6 and 7 obtained a higher percentage of inhibition of protein denaturation relative to ibuprofen.

Conclusion

The present study suggested that compound 7 may be a lead molecule because this ligand not only exhibited the best computational and experimental results but also exhibited the strongest correlation between the concentration and percentage of protein denaturation (R = 0.986 and R² = 0.972) with the lowest P-value (0.014).

Adenosine Triphosphate in Serum as a Promising Biomarker for Differential Diagnosis of Hepatitis B Disease Progression

The need to be diagnosed with liver biopsy makes the clinical progression of chronic HBV infection diagnosis a challenge. Existing HBV serum biochemical assays are used throughout clinical but have limited effects. Studies have shown that mitochondrial function is tightly coupled to HBV infection. Here, we verified the diagnostic value of serum Adenosine Triphosphate (ATP) as a potential marker for differential HBV infection progress by detecting the level of ATP in the serum from a wide spectrum of HBV-infected populations, and confirmed the role of ATP in the deterioration of HBV infection-related diseases through HBV-infected cells and mouse models. The results showed that there were significantly lower serum ATP levels in HBeAg-positive CHB patients compared with healthy controls. And during the progression of CHB to liver cirrhosis and hepatocellular carcinoma, the ATP level was increased but not higher than healthy controls. The area under the curve (AUC) of serum ATP was 0.9063 to distinguish HBeAg-positive CHB from healthy, and another AUC was 0.8328 in the CHB against the HCC group. Preliminary exploration of the mechanism indicated that the decline of serum ATP was due to impaired mitochondria in CHB patients. Our data provide evidence that serum ATP distinguishes the various progress of HBV infection-related diseases and expands diagnostic biomarkers for HBeAg-positive CHB patients with healthy controls.

Mitochondrial DNA Efflux Maintained in Gingival Fibroblasts of Patients with Periodontitis through ROS/mPTP Pathway

Mitochondria have their own mitochondrial DNA (mtDNA). Aberrant mtDNA is associated with inflammatory diseases. mtDNA is believed to induce inflammation via the abnormal mtDNA release. Periodontitis is an infectious, oral inflammatory disease. Human gingival fibroblasts (HGFs) from patients with chronic periodontitis (CP) have shown to generate higher reactive oxygen species (ROS) that cause oxidative stress and have decreased mtDNA copy number. Firstly, cell-free mtDNA was identified in plasma from CP mice through qRT-PCR. Next, we investigated whether mtDNA efflux was maintained in primary cultures of HGFs from CP patients and the possible underlying mechanisms using adenovirus-mediated transduction live cell imaging and qRT-PCR analysis. Here, we reported that mtDNA was increased in plasma from the CP mice. Additionally, we confirmed that CP HGFs had significant mtDNA efflux from mitochondria compared with healthy HGFs. Furthermore, lipopolysaccharide (LPS) from Porphyromonas gingivalis can also cause mtDNA release in healthy HGFs. Mechanistically, LPS upregulated ROS levels and mitochondrial permeability transition pore (mPTP) opening by inhibition of pyruvate dehydrogenase kinase (PDK)2 expression, resulting in mtDNA release. Importantly, mtDNA efflux was even persistent in HGFs after LPS was removed and cells were passaged to the next three generations, indicating that mtDNA abnormalities were retained in HGFs in vitro, similar to the primary hosts. Taken together, our results elucidate that mtDNA efflux was maintained in HGFs from periodontitis patients through abnormal ROS/mPTP activity. Therefore, our work indicates that persistent mtDNA efflux may be a possible diagnostic and therapeutic target for patients with periodontitis.

Oxidative Stress in Chronic Hepatitis B—An Update

In recent years, the role of oxidative stress has been investigated in an increasing number of infections. There is a close link between the inflammation that accompanies infections and oxidative stress. Excessive reactive oxygen species induce harmful effects on cell components, including lipids, proteins, and nucleic acids. A growing body of evidence attests to the role of oxidative stress in the pathogenesis of viral liver infections, especially in hepatitis C virus (HCV) infection. Regarding hepatitis B virus (HBV) infection, the data are limited, but important progress has been achieved in recent years. This review presents the latest advances pertaining to the role of the oxidative stress byproducts in the pathogenesis of chronic hepatitis B, constituting a source of potential new markers for the evaluation and monitoring of patients with chronic hepatitis B.

Overexpression of NAG-1/GDF15 prevents hepatic steatosis through inhibiting oxidative stress-mediated dsDNA release and AIM2 inflammasome activation

Mitochondrial dysfunction and oxidative stress-mediated inflammasome activation play critical roles in the pathogenesis of the non-alcoholic fatty liver disease (NAFLD). Non-steroidal anti-inflammatory drug (NSAID)-activated gene-1 (NAG-1), or growth differentiation factor-15 (GDF15), is associated with many biological processes and diseases, including NAFLD. However, the role of NAG-1/GDF15 in regulating oxidative stress and whether this process is associated with absent in melanoma 2 (AIM2) inflammasome activation in NAFLD are unknown. In this study, we revealed that NAG-1/GDF15 is significantly downregulated in liver tissues of patients with steatosis compared to normal livers using the Gene Expression Omnibus (GEO) database, and in free fatty acids (FFA, oleic acid/palmitic acid, 2:1)-induced HepG2 and Huh-7 cellular steatosis models. Overexpression of NAG-1/GDF15 in transgenic (Tg) mice significantly alleviated HFD-induced obesity and hepatic steatosis, improved lipid homeostasis, enhanced fatty acid β-oxidation and lipolysis, inhibited fatty acid synthesis and uptake, and inhibited AIM2 inflammasome activation and the secretion of IL-18 and IL-1β, as compared to their wild-type (WT) littermates without reducing food intake. Furthermore, NAG-1/GDF15 overexpression attenuated FFA-induced triglyceride (TG) accumulation, lipid metabolism deregulation, and AIM2 inflammasome activation in hepatic steatotic cells, while knockdown of NAG-1/GDF15 demonstrated opposite effects. Moreover, NAG-1/GDF15 overexpression inhibited HFD- and FFA-induced oxidative stress and mitochondrial damage which in turn reduced double-strand DNA (dsDNA) release into the cytosol, while NAG-1/GDF15 siRNA showed opposite effects. The reduced ROS production and dsDNA release may be responsible for attenuated AIM2 activation by NAG-1/GDF15 upon fatty acid overload. In conclusion, our results provide evidence that other than regulating lipid homeostasis, NAG-1/GDF15 protects against hepatic steatosis through a novel mechanism via suppressing oxidative stress, mitochondrial damage, dsDNA release, and AIM2 inflammasome activation.

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NAG-1/GDF15 is downregulated in human steatotic liver and FFA-induced liver cells.

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NAG-1/GDF15 inhibits hepatic steatosis and improves lipid homeostasis.

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AIM2 inflammasome is activated in steatosis models and is inhibited by NAG-1/GDF15.

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NAG-1/GDF15 reduces oxidative stress and mitochondrial damage in steatosis models.

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NAG-1/GDF15 inhibits mitochondrial dsDNA release and thus inhibits AIM2 activation.

The Effects of Methylene Blue and Carbon Nanoparticles on Transplanted Lymph Node Survival, Reconstructed Lymphatic Function, and Changes in Inflammatory and Fibrosis Factors

BACKGROUND AND OBJECTIVES

Methylene blue (MB) and carbon nanoparticles (CNs) can be used as a simple method for reverse lymphatic mapping. We investigated whether the two tracers had an impact on the survival of lymph nodes and the function of reconstructed lymph vessels after transplantation, as well as the changes in surrounding related factors.

METHODS

The stained lymph nodes were non-vascularized transplanted into the contralateral popliteal fossa in mice. After 4 weeks, the lymphatic recanalization was detected. The samples were harvested for pathological detection and PCR. In addition, the transport ability of the recanalized lymphatics to tumor cells was also explored.

RESULTS

Compared with the control group, there was no significant difference of the MB and CNs groups in the drainage function of recanalized lymphatic vessels, the survival of lymph nodes, or the transport capacity to tumor cells. TNF-α and IL-6 were significantly higher in the two tracer groups (**p < 0.01). Besides, the α-SMA was significantly increased in the CNs group (*p < 0.05).

CONCLUSIONS

Two tracers have no effect on the survival of transplanted lymph nodes, nor do they affect the drainage ability or tumor cell capture ability of the reconstructed lymphatics, despite improving TNF-α and IL-6 levels and the deposition of CNs.

The Lactate and the Lactate Dehydrogenase in Inflammatory Diseases and Major Risk Factors in COVID-19 Patients

Lactate dehydrogenase (LDH) is a terminating enzyme in the metabolic pathway of anaerobic glycolysis with end product of lactate from glucose. The lactate formation is crucial in the metabolism of glucose when oxygen is in inadequate supply. Lactate can also be formed and utilised by different cell types under fully aerobic conditions. Blood LDH is the marker enzyme, which predicts mortality in many conditions such as ARDS, serious COVID-19 and cancer patients. Lactate plays a critical role in normal physiology of humans including an energy source, a signaling molecule and a pH regulator. Depending on the pH, lactate exists as the protonated acidic form (lactic acid) at low pH or as sodium salt (sodium lactate) at basic pH. Lactate can affect the immune system and act as a signaling molecule, which can provide a “danger” signal for life. Several reports provide evidence that the serum lactate represents a chemical marker of severity of disease similar to LDH under inflammatory conditions. Since the mortality rate is much higher among COVID-19 patients, associated with high serum LDH, this article is aimed to review the LDH as a therapeutic target and lactate as potential marker for monitoring treatment response of inflammatory diseases. Finally, the review summarises various LDH inhibitors, which offer potential applications as therapeutic agents for inflammatory diseases, associated with high blood LDH. Both blood LDH and blood lactate are suggested as risk factors for the mortality of patients in serious inflammatory diseases.

A New Inflammation-Related Risk Model for Predicting Hepatocellular Carcinoma Prognosis

Background

Hepatocellular carcinoma (HCC) is characterized by a poor prognosis. Inflammation has a vital role in the formation and development of HCC. However, the prediction of HCC prognosis using inflammation-related genes (IRGs) remains elusive. In this study, we constructed a new IRG risk model to predict the HCC prognosis.

Results

HCC-related RNA expression profiles and their corresponding clinical data were downloaded from TCGA and ICGC databases to explore the IRGs' predicting ability. Seven hundred thirty-seven IRGs from GeneCards were used as candidate genes to construct the model. The associations of overall survival (OS) with IRGs were evaluated using the log-rank test and univariate Cox analysis, and 32 out of 737 IRGs showed predicting the potential for HCC prognosis. These IRGs were further analyzed using the least absolute shrinkage and selection operator (LASSO) and multivariate Cox analyses. Finally, 6 IRGs were included in an IRG risk model. Based on the cut-off of the risk score calculated according to the IRG risk model, HCC samples were divided into the high-risk and the low-risk groups. The OS of patients was lower in the high-risk group than in the low-risk group (P < 0.05). The area under the receiver operating characteristic curve (AUC) of the risk score was 0.78 for 3-year survival. Univariate Cox and multivariate Cox analyses revealed that the risk score was an independent risk factor for HCC prognosis. The KEGG and GO enrichment analysis results further showed that the risk scores were closely related to inflammatory and immune pathways. In addition, the ssGSEA demonstrated that several immune cells and some immune-related pathways were negatively correlated with the risk score.

Conclusions

The new IRG risk score was an independent risk factor for HCC prognosis and could be used to assess the immune status of the HCC microenvironment.

Mitochondrial-Related Transcriptome Feature Correlates with Prognosis, Vascular Invasion, Tumor Microenvironment, and Treatment Response in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is the most common subtype of primary liver cancer, which was highly correlated with metabolic dysfunction. Nevertheless, the association between nuclear mitochondrial-related transcriptome and HCC remained unclear.

Materials and Methods

A total of 147 nuclear mitochondrial-related genes (NMRGs) were downloaded from the MITOMAP: A Human Mitochondrial Genome Database. The training dataset was downloaded from The Cancer Genome Atlas (TCGA), while validation datasets were retrieved from the International Cancer Genome Consortium (ICGC) and Gene Expression Omnibus (GEO). The univariate and multivariate, and least absolute shrinkage and selection operator (LASSO) Cox regression analyses were applied to construct a NMRG signature, and the value of area under receiver operating characteristic curve (AUC) was utilized to assess the signature and nomogram. Then, data from the Genomics of Drug Sensitivity in Cancer (GDSC) were used for the evaluation of chemotherapy response in HCC.

Results

Functional enrichment of differentially expressed genes (DEGs) between HCC and paired normal tissue samples demonstrated that mitochondrial dysfunction was significantly associated with HCC development. Survival analysis showed a total of 35 NMRGs were significantly correlated with overall survival (OS) of HCC, and the LASSO Cox regression analysis further identified a 25-NMRG signature and corresponding prognosis score based on their transcriptional profiling. HCC patients were divided into high- and low-risk groups according to the median prognosis score, and high-risk patients had significantly worse OS (median OS: 27.50 vs. 83.18 months, P < 0.0001). The AUC values for OS at 1, 3, and 5 years were 0.79, 0.77, and 0.77, respectively. The prognostic capacity of NMRG signature was verified in the GSE14520 dataset and ICGC-HCC cohort. Besides, the NMRG signature outperformed each NMRG and clinical features in prognosis prediction and could also differentiate whether patients presented with vascular invasions (VIs) or not. Subsequently, a prognostic nomogram (C-index: 0.753, 95% CI: 0.703~0.804) by the integration of age, tumor metastasis, and NMRG prognosis score was constructed with the AUC values for OS at 1, 3, and 5 years were 0.82, 0.81, and 0.82, respectively. Notably, significant enrichment of regulatory and follicular helper T cells in high-risk group indicated the potential treatment of immune checkpoint inhibitors for these patients. Interestingly, the NMRG signature could also identify the potential responders of sorafenib or transcatheter arterial chemoembolization (TACE) treatment. Additionally, HCC patients in high-risk group appeared to be more sensitive to cisplatin, vorinostat, and methotrexate, reversely, patients in low-risk group had significantly higher sensitivity to paclitaxel and bleomycin instead.

Conclusions

In summary, the development of NMRG signature provided a more comprehensive understanding of mitochondrial dysfunction in HCC, helped predict prognosis and tumor microenvironment, and provided potential targeted therapies for HCC patients with different NMRG prognosis scores.

mtDNA-STING Axis Mediates Microglial Polarization via IRF3/NF-κB Signaling After Ischemic Stroke

Neuroinflammation is initiated in response to ischemic stroke, and is usually characterized by microglial activation and polarization. Stimulator of interferon genes (STING) has been shown to play a critical role in anti-tumor immunity and inflammatory diseases. Nevertheless, the effect and underlying mechanisms of STING on microglial polarization after ischemic stroke remain unclarified. In this study, acute ischemic stroke was simulated using a model of middle cerebral artery occlusion (MCAO) at adult male C57BL/6 mice in vivo and the BV2 microglia oxygen-glucose deprivation/reperfusion (OGD/R) model in vitro. The specific STING inhibitor C-176 was administered intraperitoneally at 30min after MCAO. We found that the expression of microglial STING was increased following MCAO and OGD/R. Pharmacologic inhibition of STING with C-176 reduced the ischemia/reperfusion (I/R)-induced brain infarction, edema and neuronal injury. Moreover, blockade of STING improved neurological performance and cognitive function and attenuated neuronal degeneration in the hippocampus after MCAO. Mechanistically, both in vivo and in vitro, we delineated that STING could promote the polarization of microglia towards the M1 phenotype and restrain M2 microglia polarization via downstream pathways, including interferon regulatory factor 3 (IRF3) and nuclear factor-κB (NF-κB). In addition, mitochondrial DNA (mtDNA), which is released to microglial cytoplasm induced by I/R injury, could facilitate microglia towards M1 modality through STING signaling pathway. Treatment with C-176 abolished the detrimental effects of mtDNA on stroke outcomes. Taken together, these findings suggest that STING, activated by mtDNA, could polarize microglia to the M1 phenotype following MCAO. Inhibition of STING may serve as a potential therapeutic strategy to mitigate neuroinflammation after ischemic stroke.

Mitochondrial DNA Release Contributes to Intestinal Ischemia/Reperfusion Injury

Mitochondria release many damage-associated molecular patterns (DAMPs) when cells are damaged or stressed, with mitochondrial DNA (mtDNA) being. MtDNA activates innate immune responses and induces inflammation through the TLR-9, NLRP3 inflammasome, and cGAS-STING signaling pathways. Released inflammatory factors cause damage to intestinal barrier function. Many bacteria and endotoxins migrate to the circulatory system and lymphatic system, leading to systemic inflammatory response syndrome (SIRS) and even damaging the function of multiple organs throughout the body. This process may ultimately lead to multiple organ dysfunction syndrome (MODS). Recent studies have shown that various factors, such as the release of mtDNA and the massive infiltration of inflammatory factors, can cause intestinal ischemia/reperfusion (I/R) injury. This destroys intestinal barrier function, induces an inflammatory storm, leads to SIRS, increases the vulnerability of organs, and develops into MODS. Mitophagy eliminates dysfunctional mitochondria to maintain cellular homeostasis. This review discusses mtDNA release during the pathogenesis of intestinal I/R and summarizes methods for the prevention or treatment of intestinal I/R. We also discuss the effects of inflammation and increased intestinal barrier permeability on drugs.

Adipose-derived stem cells alleviate liver injury induced by type 1 diabetes mellitus by inhibiting mitochondrial stress and attenuating inflammation

Background

Type 1 diabetes mellitus (T1D) is a worldwide health priority due to autoimmune destruction and is associated with an increased risk of multiorgan complications. Among these complications, effective interventions for liver injury, which can progress to liver fibrosis and hepatocellular carcinoma, are lacking. Although stem cell injection has a therapeutic effect on T1D, whether it can cure liver injury and the underlying mechanisms need further investigation.

Methods

Sprague–Dawley rats with streptozotocin (STZ)-induced T1D were treated with adipose-derived stem cell (ADSC) or PBS via the tail vein formed the ADSC group or STZ group. Body weights and blood glucose levels were examined weekly for 6 weeks. RNA-seq and PCR array were used to detect the difference in gene expression of the livers between groups.

Results

In this study, we found that ADSCs injection alleviated hepatic oxidative stress and injury and improved liver function in rats with T1D; potential mechanisms included cytokine activity, energy metabolism and immune regulation were potentially involved, as determined by RNA-seq. Moreover, ADSC treatment altered the fibroblast growth factor 21 (FGF21) and transforming growth factor β (TGF-β) levels in T1D rat livers, implying its repair capacity. Disordered intracellular energy metabolism, which is closely related to mitochondrial stress and dysfunction, was inhibited by ADSC treatment. PCR array and ingenuity pathway analyses suggested that the ADSC-induced suppression of mitochondrial stress is related to decreased necroptosis and apoptosis. Moreover, mitochondria-related alterations caused liver inflammation, resulting in liver injury involving the T lymphocyte-mediated immune response.

Conclusions

Overall, these results improve our understanding of the curative effect of ADSCs on T1D complications: ADSCs attenuate liver injury by inhibiting mitochondrial stress (apoptosis and dysfunctional energy metabolism) and alleviating inflammation (inflammasome expression and immune disorder). These results are important for early intervention in liver injury and for delaying the development of liver lesions in patients with T1D.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02760-z.

Mitochondrial DNA as a Possible Ligand for TLR9 in Irinotecan-induced Small Intestinal Mucositis

Cancer chemotherapy and radiotherapy may result in mucositis characterized by stem cell damage and inflammation in the gastrointestinal tract. The molecular mechanisms underlying this pathology remain unknown. Based on the assumption that mitochondrial CPG-DNA (mtDNA) released and sensed by TLR9 could underlie mucositis pathology, we analyzed the mtDNA levels in sera as well as inflammatory and disease parameters in the small intestine from wild-type (WT) and TLR9-deficient mice (TLR9-/-) in an experimental model of intestinal mucositis induced by irinotecan. Additionally, we verified the ability of WT and TLR9-/- macrophages to respond to CpG-DNA in vitro. WT mice injected with irinotecan presented a progressive increase in mtDNA in the serum along with increased hematocrit, shortening of small intestine length, reduction of intestinal villus:crypt ratio and increased influx of neutrophils, which were followed by higher expression of Nlrp3 and Casp1 mRNA and increased IL-1β levels in the ileum when compared to vehicle-injected mice. TLR9-deficient mice were protected in all these parameters when compared to WT mice. Furthermore, TLR9 was required for the production of IL-1β and NO after macrophage stimulation with CpG-DNA. Overall, our findings show that the amount of circulating free CpG-DNA is increased upon chemotherapy and that TLR9 activation is important for NLRP3 inflammasome transcription and further IL-1β release, playing a central role in the development of irinotecan-induced intestinal mucositis. We suggest that TLR9 antagonism may be a new therapeutic strategy for limiting irinotecan-induced intestinal inflammation.

Immune and Metabolic Alterations in Liver Fibrosis: A Disruption of Oxygen Homeostasis?

According to the WHO, “cirrhosis of the liver” was the 11th leading cause of death globally in 2019. Many kinds of liver diseases can develop into liver cirrhosis, and liver fibrosis is the main pathological presentation of different aetiologies, including toxic damage, viral infection, and metabolic and genetic diseases. It is characterized by excessive synthesis and decreased decomposition of extracellular matrix (ECM). Hepatocyte cell death, hepatic stellate cell (HSC) activation, and inflammation are crucial incidences of liver fibrosis. The process of fibrosis is also closely related to metabolic and immune disorders, which are usually induced by the destruction of oxygen homeostasis, including mitochondrial dysfunction, oxidative stress, and hypoxia pathway activation. Mitochondria are important organelles in energy generation and metabolism. Hypoxia-inducible factors (HIFs) are key factors activated when hypoxia occurs. Both are considered essential factors of liver fibrosis. In this review, the authors highlight the impact of oxygen imbalance on metabolism and immunity in liver fibrosis as well as potential novel targets for antifibrotic therapies.

Hepatitis B Virus Infection and Extra-Hepatic Manifestations: A Systemic Disease

People living with hepatitis B virus (HBV) chronic infection are exposed to high rates of liver complications including end-stage liver disease and hepatocellular carcinoma. Extrahepatic manifestations of HBV infection have long been underestimated. Several of these extrahepatic syndromes have been well described, including systemic vasculitides, glomerulonephritis, and cutaneous manifestations. Other manifestations have been more recently described such as hematological malignancies and neurological diseases. These extrahepatic manifestations are associated with significant morbidity and mortality. Although not completely understood, underlying mechanisms include HBV-induced local and systemic inflammation. Suppression of HBV replication usually improves extrahepatic manifestations. This review will discuss how HBV induces inflammation and the extrahepatic manifestations of HBV infection to guide clinical management.

Elevated levels of circulating mitochondrial DNA predict early allograft dysfunction in patients following liver transplantation

BACKGROUND AND AIM

The role of circulating mitochondrial DNA (cmtDNA) in transplantation remains to be elucidated. cmtDNA may be released into the circulation as a consequence of liver injury; yet recent work also suggests a causative role for cmtDNA leading to hepatocellular injury. We hypothesized that elevated cmtDNA would be associated with adverse events after liver transplantation (LT) and conducted an observational cohort study.

METHODS

Twenty-one patients were enrolled prospectively prior to LT.

RESULTS

Postoperative complications were observed in 47.6% (n = 10). Seven patients (33.3%) had early allograft dysfunction (EAD), and six patients (28.5%) experienced acute cellular rejection within 6 months of LT. cmtDNA levels were significantly elevated in all recipients after LT compared with healthy controls and preoperative samples (1 361 937 copies/mL [IQR 586 781-3 399 687] after LT; 545 531 copies/mL [IQR 238 562-1 381 015] before LT; and 194 562 copies/mL [IQR 182 359-231 515] in healthy controls) and returned to normal levels by 5 days after transplantation. cmtDNA levels were particularly elevated in those who developed EAD in the early postoperative period (P < 0.001). In all patients, there was initially a strong overall positive correlation between cmtDNA and plasma hepatocellular enzyme levels (P < 0.05). However, the patients with EAD demonstrated a second peak in cmtDNA at postoperative day 7, which did not correlate with liver function tests.

CONCLUSIONS

The early release of plasma cmtDNA is strongly associated with hepatocellular damage; however, the late surge in cmtDNA in patients with EAD appeared to be independent of hepatocellular injury as measured by conventional tests.