Regulation of mitochondrial biogenesis and its intersection with inflammatory responses

Pyroptosis and Redox Balance in Kidney Diseases

Significance: Kidney diseases remain a worldwide public health problem resulting in millions of deaths each year; they are characterized by progressive destruction of renal function by sustained inflammation. Pyroptosis is a lytic type of programmed cell death involved in inflammation, as well as a key fibrotic mechanism that is critical in the development of kidney pathology. Pyroptosis is induced by the cleavage of Gasdermins by various caspases and is executed by the insertion of the N-terminal fragment of cleaved Gasdermins into the plasma membrane, creating oligomeric pores and allowing the release of diverse proinflammatory products into the extracellular space. Inflammasomes are multiprotein complexes leading to the activation of caspase-1, which will cleave Gasdermin D, releasing several proinflammatory cytokines; this results in the initiation and amplification of the inflammatory response. Recent Advances: The efficacy of Gasdermin D cleavage is reduced by a change in the redox balance. Recently, several studies have shown that the attenuation of reactive oxygen species (ROS) production induced by antioxidant pathways results in a reduction of renal pyroptosis. In this review, we discuss the role of pyroptosis in the pathogenesis of chronic kidney disease (CKD) and acute kidney disease; summarize the clinical outcomes and different molecular mechanisms leading to Gasdermin activation; and examine studies about the capacity of antioxidants, particularly Nrf2 activators, to ameliorate Gasdermin activity. Future Directions: We illustrate the potential influence of the deregulation of redox balance on inflammasome activity and pyroptosis as a novel therapeutic approach for the treatment of kidney diseases. Antioxid. Redox Signal. 35, 40-60.

Bilateral visual improvement with unilateral gene therapy injection for Leber hereditary optic neuropathy

REVERSE is a randomized, double-masked, sham-controlled, multicenter, phase 3 clinical trial that evaluated the efficacy of a single intravitreal injection of rAAV2/2-ND4 in subjects with visual loss from Leber hereditary optic neuropathy (LHON). A total of 37 subjects carrying the m.11778G>A (MT-ND4) mutation and with duration of vision loss between 6 to 12 months were treated. Each subject's right eye was randomly assigned in a 1:1 ratio to treatment with rAAV2/2-ND4 (GS010) or sham injection. The left eye received the treatment not allocated to the right eye. Unexpectedly, sustained visual improvement was observed in both eyes over the 96-week follow-up period. At week 96, rAAV2/2-ND4-treated eyes showed a mean improvement in best-corrected visual acuity (BCVA) of -0.308 LogMAR (+15 ETDRS letters). A mean improvement of -0.259 LogMAR (+13 ETDRS letters) was observed in the sham-treated eyes. Consequently, the primary end point, defined as the difference in the change in BCVA from baseline to week 48 between the two treatment groups, was not met (P = 0.894). At week 96, 25 subjects (68%) had a clinically relevant recovery in BCVA from baseline in at least one eye, and 29 subjects (78%) had an improvement in vision in both eyes. A nonhuman primate study was conducted to investigate this bilateral improvement. Evidence of transfer of viral vector DNA from the injected eye to the anterior segment, retina, and optic nerve of the contralateral noninjected eye supports a plausible mechanistic explanation for the unexpected bilateral improvement in visual function after unilateral injection.

Aldose reductase regulates doxorubicin-induced immune and inflammatory responses by activating mitochondrial biogenesis

We have recently demonstrated that aldose reductase (AR) inhibitor; fidarestat prevents doxorubicin (Dox)-induced cardiotoxic side effects and inflammation in vitro and in vivo. However, the effect of fidarestat and its combination with Dox on immune cell activation and the immunomodulatory effects are not known. In this study, we examined the immunomodulatory effects of fidarestat in combination with Dox in vivo and in vitro. We observed that fidarestat decreased Dox-induced upregulation of CD11b in THP-1 monocytes. Fidarestat further attenuated Dox-induced upregulation of IL-6, IL-1β, and Nos2 in murine BMDM. Fidarestat also attenuated Dox-induced activation and infiltration of multiple subsets of inflammatory immune cells identified by expression of markers CD11b+, CD11b+F4/80+, Ly6C+CCR2high, and Ly6C+CD11b+ in the mouse spleen and liver. Furthermore, significant upregulation of markers of mitochondrial biogenesis PGC-1α, COX IV, TFAM, and phosphorylation of AMPKα1 (Ser485) was observed in THP-1 cells and livers of mice treated with Dox in combination with fidarestat. Our results suggest that fidarestat by up-regulating mitochondrial biogenesis exerts protection against Dox-induced immune and inflammatory responses in vitro and in vivo, providing further evidence for developing fidarestat as a combination agent with anthracycline drugs to prevent chemotherapy-induced inflammation and toxicity.

Notoginsenoside R1 alleviates TEGDMA-induced mitochondrial apoptosis in preodontoblasts through activation of Akt/Nrf2 pathway-dependent mitophagy

Incomplete polymerization or biodegradation of dental resin materials results in the release of resin monomers such as triethylene glycol dimethacrylate (TEGDMA), causing severe injury of dental pulp cells. To date, there has been no efficient treatment option for this complication, in part due to the lack of understanding of the mechanism underlying these phenomena. Here, for the first time, we found that notoginsenoside R1 (NR1), a bioactive ingredient extracted from Panax notoginseng, exerted an obvious protective effect on TEGDMA-induced mitochondrial apoptosis in the preodontoblast mDPC6T cell line. In terms of the mechanism of action, NR1 enhanced the level of phosphorylated Akt (protein kinase B), resulting in the activation of a transcriptional factor, nuclear factor erythroid 2-related factor 2 (Nrf2), and eventually upregulating cellular ability to resist TEGDMA-related toxicity. Inhibiting the Akt/Nrf2 pathway by pharmaceutical inhibitors significantly decreased NR1-mediated cellular antioxidant properties and aggravated mitochondrial oxidative damage in TEGDMA-treated cells. Interestingly, NR1 also promoted mitophagy, which was identified as the potential downstream of the Akt/Nrf2 pathway. Blocking the Akt/Nrf2 pathway inhibited mitophagy and abolished the protection of NR1 on cells exposed to TEGDMA. In conclusion, these findings reveal that the activation of Akt/Nrf2 pathway-mediated mitophagy by NR1 might be a promising approach for preventing resin monomer-induced dental pulp injury.

Cyclophilin D-dependent mitochondrial permeability transition amplifies inflammatory reprogramming in endotoxemia

Microorganisms or LPS (lipopolysaccharide), an outer membrane component of Gram-negative bacteria, can induce a systemic inflammatory response that leads to sepsis, multiple organ dysfunction, and mortality. Here, we investigated the role of cyclophilin D (CypD)-dependent mitochondrial permeability transition (mPT) in the immunosuppressive phase of LPS-induced endotoxic shock. The liver plays an important role in immunity and organ dysfunction; therefore, we used liver RNA sequencing (RNA-seq) data, Ingenuity® Pathway Analysis (IPA ® ) to investigate the complex role of mPT formation in inflammatory reprogramming and disease progression. LPS induced significant changes in the expression of 2844 genes, affecting 179 pathways related to mitochondrial dysfunction, defective oxidative phosphorylation, nitric oxide (NO) and reactive oxygen species (ROS) accumulation, nuclear factor, erythroid 2 like 2 (Nrf2), Toll-like receptors (TLRs), and tumor necrosis factor α receptor (TNFR)-mediated processes in wild-type mice. The disruption of CypD reduced LPS-induced alterations in gene expression and pathways involving TNFRs and TLRs, in addition to improving survival and attenuating oxidative liver damage and the related NO- and ROS-producing pathways. CypD deficiency diminished the suppressive effect of LPS on mitochondrial function, nuclear- and mitochondrial-encoded genes, and mitochondrial DNA (mtDNA) quantity, which could be critical in improving survival. Our data propose that CypD-dependent mPT is an amplifier in inflammatory reprogramming and promotes disease progression. The mortality in human sepsis and shock is associated with mitochondrial dysfunction. Prevention of mPT by CypD disruption reduces inflammatory reprogramming, mitochondrial dysfunction, and lethality; therefore, CypD can be a novel drug target in endotoxic shock and related inflammatory diseases.

Energy, Entropy and Quantum Tunneling of Protons and Electrons in Brain Mitochondria: Relation to Mitochondrial Impairment in Aging-Related Human Brain Diseases and Therapeutic Measures

Adult human brains consume a disproportionate amount of energy substrates (2-3% of body weight; 20-25% of total glucose and oxygen). Adenosine triphosphate (ATP) is a universal energy currency in brains and is produced by oxidative phosphorylation (OXPHOS) using ATP synthase, a nano-rotor powered by the proton gradient generated from proton-coupled electron transfer (PCET) in the multi-complex electron transport chain (ETC). ETC catalysis rates are reduced in brains from humans with neurodegenerative diseases (NDDs). Declines of ETC function in NDDs may result from combinations of nitrative stress (NS)-oxidative stress (OS) damage; mitochondrial and/or nuclear genomic mutations of ETC/OXPHOS genes; epigenetic modifications of ETC/OXPHOS genes; or defects in importation or assembly of ETC/OXPHOS proteins or complexes, respectively; or alterations in mitochondrial dynamics (fusion, fission, mitophagy). Substantial free energy is gained by direct O2-mediated oxidation of NADH. Traditional ETC mechanisms require separation between O2 and electrons flowing from NADH/FADH2 through the ETC. Quantum tunneling of electrons and much larger protons may facilitate this separation. Neuronal death may be viewed as a local increase in entropy requiring constant energy input to avoid. The ATP requirement of the brain may partially be used for avoidance of local entropy increase. Mitochondrial therapeutics seeks to correct deficiencies in ETC and OXPHOS.

Mitochondrial Regulation of Macrophage Response Against Pathogens

Innate immune cells play the first line of defense against pathogens. Phagocytosis or invasion by pathogens can affect mitochondrial metabolism in macrophages by diverse mechanisms and shape the macrophage response (proinflammatory vs. immunomodulatory) against pathogens. Besides β-nicotinamide adenine dinucleotide 2'-phosphate, reduced (NADPH) oxidase, mitochondrial electron transport chain complexes release superoxide for direct killing of the pathogen. Mitochondria that are injured are removed by mitophagy, and this process can be critical for regulating macrophage activation. For example, impaired mitophagy can result in cytosolic leakage of mitochondrial DNA (mtDNA) that can lead to activation of cGAS-STING signaling pathway of macrophage proinflammatory response. In this review, we will discuss how metabolism, mtDNA, mitophagy, and cGAS-STING pathway shape the macrophage response to infectious agents.

Evidence of Mitochondrial Dysfunction in Bacterial Chondronecrosis With Osteomyelitis-Affected Broilers

A leading cause of lameness in modern broilers is bacterial chondronecrosis with osteomyelitis (BCO). While it is known that the components of BCO are bacterial infection, necrosis, and inflammation, the mechanism behind BCO etiology is not yet fully understood. In numerous species, including chicken, mitochondrial dysfunction has been shown to have a role in the pathogenicity of numerous diseases. The mitochondria is a known target for intracellular bacterial infections, similar to that of common causative agents in BCO, as well as a known regulator of cellular metabolism, stress response, and certain types of cell death. This study aimed to determine the expression profile of genes involved in mitochondrial biogenesis, dynamics, and function. RNA was isolated form the tibias from BCO-affected and healthy broilers and used to measure target gene expression via real-time qPCR. Mitochondrial biogenesis factors PGC-1α and PGC-1β were both significantly upregulated in BCO along with mitochondrial fission factors OMA1, MTFR1, MTFP1, and MFF1 as well as cellular respiration-related genes FOXO3, FOXO4, and av-UCP. Conversely, genes involved in mitochondrial function, ANT, COXIV, and COX5A showed decreased mRNA levels in BCO-affected tibia. This study is the first to provide evidence of potential mitochondrial dysfunction in BCO bone and warrants further mechanistic investigation into how this dysfunction contributes to BCO etiology.

Caloric restriction reduces sympathetic activity similar to beta-blockers but conveys additional mitochondrio-protective effects in aged myocardium

Increased activation of sympathetic nervous system contributes to congestive heart failure (CHF) progression, and inhibition of sympathetic overactivation by beta-blockers is successful in CHF patients. Similarly, caloric restriction (CR) reduces sympathetic activity but mediates additional effects. Here, we compared the cardiac effects of CR (− 40% kcal, 3 months) with beta-blocker therapy (BB), diuretic medication (DF) or control diet in 18-months-old Wistar rats. We continuously recorded blood pressure, heart rate, body temperature and activity with telemetric devices and analysed cardiac function, activated signalling cascades and markers of apoptosis and mitochondrial biogenesis. During our study, left ventricular (LV) systolic function improved markedly (CR), mildly (BB) or even deteriorated (DF; control). Diastolic function was preserved by CR and BB but impaired by DF. CR reduced blood pressure identical to DF and BB and heart rate identical to BB. Plasma noradrenaline was decreased by CR and BB but increased by DF. Only CR reduced LV oxidative damage and apoptosis, induced AMPK and Akt phosphorylation and increased mitochondrial biogenesis. Thus, additive to the reduction of sympathetic activity, CR achieves protective effects on mitochondria and improves LV function and ROS damage in aged hearts. CR mechanisms may provide additional therapeutic targets compared to traditional CHF therapy.

Transient Early Fine Motor Abnormalities in Infants Born to COVID-19 Mothers Are Associated With Placental Hypoxia and Ischemia

Background: Long-term effects of Coronavirus Disease 2019 (COVID-19) on infants born to infected mothers are not clear. Fine motor skills are crucial for the development of infant emotional regulation, learning ability and social skills. Methods: Clinical information of 100 infants born to 98 mothers (COVID-19 n = 31, non-COVID-19 n = 67) were collected. Infants were follow-up up to 9 months post-partum. The placental tissues were examined for SARS-CoV-2 infection, pathological changes, cytokines, and mtDNA content. Results: Decreased placental oxygen and nutrient transport capacity were found in infected pregnant women. Increased IL-2, IL-6, TNF-α, and IFN-γ were detected in trophoblast cells and maternal blood of COVID-19 placentas. Elevated early fine motor abnormal-ities and increased serum TNI (troponin I) levels at delivery were observed in infants born to mothers with COVID-19. Increased abnormal mitochondria and elevated mtDNA content were found in the placentas from infected mothers. The placental mtDNA content of three infants with abnormal DDST were increased by 4, 7, and 10%, respectively, compared to the mean of the COVID-19 group. The Maternal Vascular Malperfusion (MVM), elevated cytokines and increased placental mtDNA content in mothers with COVID-19 might be associated with transient early fine motor abnormalities in infants. These abnormalities are only temporary, and they could be corrected by daily training. Conclusions: Babies born to COVID-19 mothers with mild symptoms appeared to have little or no excess long-term risks of abnormal physical and neurobehavioral development as compared with the infants delivered by non-COVID-19 mothers.

The nuclear factor kappa B (NF-κB) signaling pathway is involved in ammonia-induced mitochondrial dysfunction

Hyperammonemia is very toxic to the brain, leading to inflammation, disruption of brain cellular energy metabolism and cognitive function. However, the underlying mechanism(s) for these impairments is still not fully understood. This study investigated the effects of ammonia in hippocampal astroglia derived from C57BL/6 mice. Parameters measured included oxygen consumption rates (OCR), ATP, cytochrome c oxidase (COX) activity, alterations in oxidative phosphorylation (OXPHOS), nuclear factor kappa B (NF-κB) subunits, key regulators of mitochondrial biogenesis (peroxisome proliferator-activated receptor gamma coactivator1-alpha (PGC-1α), calcium/calmodulin-dependent protein kinase II (CaMKII), cAMP-response element binding protein (CREB), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), early growth response (Egr) factor family of proteins, and mitochondrial transcription factor A (TFAM). Ammonia was found to decrease mitochondrial numbers, potentially through a CaMKII-CREB-PGC1α-Nrf2 pathway in astroglia. Ammonia did not alter the levels of Egrs and TFAM in astroglia. Ammonia decreased OCR, ATP, COX, and OXPHOS levels in astroglia. To assess whether energy metabolism is reduced by ammonia through NF-κB associated pathways, astroglia were treated with ammonia alone or with NF-κB inhibitors such as Bay11-7082 or SN50. Mitochondrial OCR levels were reduced in the presence of NF-κB inhibitors; however co-treatment of NF-κB inhibitors and ammonia reversed mitochondrial deficits. Further, ammonia increased translocation of the NF-κB p65 into the nucleus of astroglia that correlates with an increased activity of NF-κB. These findings suggest that the NF-κB signaling pathway is putatively involved in ammonia-induced changes in bioenergetics in astroglia. Such research has critical implications for the treatment of disorders in which brain bioenergetics is compromised.

Gasotransmitter signaling in energy homeostasis and metabolic disorders

Gasotransmitters are small molecules of gases, including nitric oxide (NO), hydrogen sulfide (H₂S), and carbon monoxide (CO). These three gasotransmitters can be endogenously produced and regulate a wide range of pathophysiological processes by interacting with specific targets upon diffusion in the biological media. By redox and epigenetic regulation of various physiological functions, NO, H₂S, and CO are critical for the maintenance of intracellular energy homeostasis. Accumulated evidence has shown that these three gasotransmitters control ATP generation, mitochondrial biogenesis, glucose metabolism, insulin sensitivity, lipid metabolism, and thermogenesis, etc. Abnormal generation and metabolism of NO, H₂S, and/or CO are involved in various abnormal metabolic diseases, including obesity, diabetes, and dyslipidemia. In this review, we summarized the roles of NO, H₂S, and CO in the regulation of energy homeostasis as well as their involvements in the metabolism of dysfunction-related diseases. Understanding the interaction among these gasotransmitters and their specific molecular targets are very important for therapeutic applications.

Mitochondrial dysfunction in sepsis is associated with diminished intramitochondrial TFAM despite its increased cellular expression

Sepsis is characterized by a dysregulated immune response, metabolic derangements and bioenergetic failure. These alterations are closely associated with a profound and persisting mitochondrial dysfunction. This however occurs despite increased expression of the nuclear-encoded transcription factor A (TFAM) that normally supports mitochondrial biogenesis and functional recovery. Since this paradox may relate to an altered intracellular distribution of TFAM in sepsis, we tested the hypothesis that enhanced extramitochondrial TFAM expression does not translate into increased intramitochondrial TFAM abundance. Accordingly, we prospectively analyzed PBMCs both from septic patients (n = 10) and lipopolysaccharide stimulated PBMCs from healthy volunteers (n = 20). Extramitochondrial TFAM protein expression in sepsis patients was 1.8-fold greater compared to controls (p = 0.001), whereas intramitochondrial TFAM abundance was approximate 80% less (p < 0.001). This was accompanied by lower mitochondrial DNA copy numbers (p < 0.001), mtND1 expression (p < 0.001) and cellular ATP content (p < 0.001) in sepsis patients. These findings were mirrored in lipopolysaccharide stimulated PBMCs taken from healthy volunteers. Furthermore, TFAM-TFB2M protein interaction within the human mitochondrial core transcription initiation complex, was 74% lower in septic patients (p < 0.001). In conclusion, our findings, which demonstrate a diminished mitochondrial TFAM abundance in sepsis and endotoxemia, may help to explain the paradox of lacking bioenergetic recovery despite enhanced TFAM expression.

When Friendship Turns Sour: Effective Communication Between Mitochondria and Intracellular Organelles in Parkinson's Disease

Parkinson's disease (PD) is a complex neurodegenerative disease with pathological hallmarks including progressive neuronal loss from the substantia nigra pars compacta and α-synuclein intraneuronal inclusions, known as Lewy bodies. Although the etiology of PD remains elusive, mitochondrial damage has been established to take center stage in the pathogenesis of PD. Mitochondria are critical to cellular energy production, metabolism, homeostasis, and stress responses; the association with PD emphasizes the importance of maintenance of mitochondrial network integrity. To accomplish the pleiotropic functions, mitochondria are dynamic not only within their own network but also in orchestrated coordination with other organelles in the cellular community. Through physical contact sites, signal transduction, and vesicle transport, mitochondria and intracellular organelles achieve the goals of calcium homeostasis, redox homeostasis, protein homeostasis, autophagy, and apoptosis. Herein, we review the finely tuned interactions between mitochondria and surrounding intracellular organelles, with focus on the nucleus, endoplasmic reticulum, Golgi apparatus, peroxisomes, and lysosomes. Participants that may contribute to the pathogenic mechanisms of PD will be highlighted in this review.

Dose- and time-dependent effects of an immune challenge on fish across biological levels

Due to global changes, fish are increasingly exposed to immune challenges associated with disease outbreaks in aquatic ecosystems. Adjustments in physiology and behavior are generally critical to maintaining homeostasis after an immune challenge, but there is limited knowledge on the specific thresholds and dynamics of responses across levels of biological organization in fish. In this study, we tested how different concentrations of an antigens mixture (phytohemagglutinin and lipopolysaccharide) affected innate immunity with potential consequences on oxidative stress, energy reserves, body condition, and behavior across time, using the common gudgeon (Gobio sp.) as model species. The immune challenge induced a transitory increase in lytic enzyme activity (i.e., lysozyme) and local immune response (i.e., skin swelling) 2 days after the antigen injection. The available energy stored in muscle was also reduced 4 days after injection, without inducing oxidative stress at the cellular level. Overall, the immune challenge induced limited costs at the molecular and cellular levels but had strong effects at the whole organism level, especially on behavior. Indeed, fish swimming activity and sociability were affected in a dose- and time-dependent manner. These results suggest that immune challenges have dose-dependent effects across levels of biological organization and that behavior is a key response trait to cope with pathogen-induced immune costs in the wild, although fitness consequences remain to be tested.

Electroacupuncture Improves Cognition in Rats With Sepsis-Associated Encephalopathy

BACKGROUND

Sepsis-associated encephalopathy (SAE) is a common complication of sepsis. Although sepsis is effectively managed with the administration of antibiotics and source control, which may include surgical intervention, SAE usually leads to prolonged cognitive dysfunction affecting the quality of life of the patients. In this study, we investigated the possible effect of electroacupuncture (EA) on cognition in a model of SAE induced by cecal ligation and puncture (CLP).

MATERIALS AND METHODS

The rats were randomly divided into four groups: the control group, the CLP group, the CLP with EA treatment group (CLP + EA), and the CLP with sham EA treatment group (CLP + sham EA). EA at DU20, LI11, and ST36 or sham EA was performed 30 min daily for 10 consecutive days starting from 2 days before CLP. Then cognitive function was examined by the Morris water maze test. On day 14 after CLP surgery, the synaptic injury, neuron loss, and oxidative stress were studied.

RESULTS

Rats with EA treatment showed improved survival rate, spatial learning, and memory abilities. The dendritic spine density, the synaptic proteins, and the hippocampal neuron number were also increased after EA treatment. Furthermore, EA suppressed oxidative stress through regulating the level of malondialdehyde and superoxide dismutase and enhanced the expression of antioxidant nuclear factor erythroid-2-related factor-2 and hemeoxygenase-1. But sham EA did not have the same effect.

CONCLUSIONS

EA may protect against SAE-induced cognitive dysfunction by inhibiting synaptic injury, neuronal loss, and oxidative stress, and the nuclear factor erythroid-2-related factor-2/hemeoxygenase-1 signaling pathway may be involved in this effect.

Nuclear Factor Kappa B Signaling Complexes in Acute Inflammation

Significance: Nuclear factor kappa B (NF-κB) is a master regulator of the inflammatory response and represents a key regulatory node in the complex inflammatory signaling network. In addition, selective NF-κB transcriptional activity on specific target genes occurs through the control of redox-sensitive NF-κB interactions. Recent Advances: The selective NF-κB response is mediated by redox-modulated NF-κB complexes with ribosomal protein S3 (RPS3), Pirin (PIR). cAMP response element-binding (CREB)-binding protein (CBP)/p300, peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), activator protein-1 (AP-1), signal transducer and activator of transcription 3 (STAT3), early growth response protein 1 (EGR-1), and SP-1. NF-κB is cooperatively coactivated with AP-1, STAT3, EGR-1, and SP-1 during the inflammatory process, whereas NF-κB complexes with CBP/p300 and PGC-1α regulate the expression of antioxidant genes. PGC-1α may act as selective repressor of phospho-p65 toward interleukin-6 (IL-6) in acute inflammation. p65 and nuclear factor erythroid 2-related factor 2 (NRF2) compete for binding to coactivator CBP/p300 playing opposite roles in the regulation of inflammatory genes. S-nitrosylation or tyrosine nitration favors the recruitment of specific NF-κB subunits to κB sites. Critical Issues: NF-κB is a redox-sensitive transcription factor that forms specific signaling complexes to regulate selectively the expression of target genes in acute inflammation. Protein-protein interactions with coregulatory proteins, other transcription factors, and chromatin-remodeling proteins provide transcriptional specificity to NF-κB. Furthermore, different NF-κB subunits may form distinct redox-sensitive homo- and heterodimers with distinct affinities for κB sites. Future Directions: Further research is required to elucidate the whole NF-κB interactome to fully characterize the complex NF-κB signaling network in redox signaling, inflammation, and cancer.

Sirtuin-1 expression and activity is diminished in aged liver grafts

The cellular mechanisms underlying impaired function of aged liver grafts have not been fully elucidated, but mitochondrial dysfunction appears to be contributory. Sirtuin1 has been identified as a key mediator of mitochondrial recovery following ischemia-reperfusion injury. The purpose of this study was to determine whether differences exist in sirtuin-1 expression/activity in old vs. young liver grafts and to determine correlations with mitochondrial function, graft metabolic function, and graft injury. Old and young rat liver grafts (N = 7 per group) were exposed to 12 h of static cold storage (SCS), followed by a 2 h period of graft reperfusion ex vivo. Sirtuin1 expression and activity, mitochondrial function, graft metabolic function, and graft injury were compared. Sirtuin1 expression is upregulated in young, but not old, liver grafts in response to cold storage and reperfusion. This is associated with diminished tissue ATP, antioxidant defense, and graft metabolic function in old liver grafts. There was no evidence of increased inflammation or histologic injury in old grafts. Sirtuin1 expression is diminished in old liver grafts and correlates with mitochondrial and metabolic function. The sirtuin pathway may represent a target for intervention to enhance the function of aged liver grafts.

Lack of mitochondrial NADP(H)-transhydrogenase expression in macrophages exacerbates atherosclerosis in hypercholesterolemic mice

The atherosclerosis prone LDL receptor knockout mice (Ldlr-/-, C57BL/6J background) carry a deletion of the NADP(H)-transhydrogenase gene (Nnt) encoding the mitochondrial enzyme that catalyzes NADPH synthesis. Here we hypothesize that both increased NADPH consumption (due to increased steroidogenesis) and decreased NADPH generation (due to Nnt deficiency) in Ldlr-/- mice contribute to establish a macrophage oxidative stress and increase atherosclerosis development. Thus, we compared peritoneal macrophages and liver mitochondria from three C57BL/6J mice lines: Ldlr and Nnt double mutant, single Nnt mutant and wild-type. We found increased oxidants production in both mitochondria and macrophages according to a gradient: double mutant > single mutant > wild-type. We also observed a parallel up-regulation of mitochondrial biogenesis (PGC1a, TFAM and respiratory complexes levels) and inflammatory (iNOS, IL6 and IL1b) markers in single and double mutant macrophages. When exposed to modified LDL, the single and double mutant cells exhibited significant increases in lipid accumulation leading to foam cell formation, the hallmark of atherosclerosis. Nnt deficiency cells showed up-regulation of CD36 and down-regulation of ABCA1 transporters what may explain lipid accumulation in macrophages. Finally, Nnt wild-type bone marrow transplantation into LDLr-/- mice resulted in reduced diet-induced atherosclerosis. Therefore, Nnt plays a critical role in the maintenance of macrophage redox, inflammatory and cholesterol homeostasis, which is relevant for delaying the atherogenesis process.

Metabolic disturbance in Korean red ginseng-induced "Shanghuo" (excessive heat)

ETHNOPHARMACOLOGICAL RELEVANCE

Northeast China is one of the Korean Red Ginseng (KRG) producing areas. As a health care product, KRG is popular amongst Chinese people. However, few studies have reported the side effects of overusing KRG.

AIM OF THE STUDY

The main purpose of this study is to explore the mechanism of Korean Red Ginseng (KRG)-induced "Shanghuo" (excessive heat).

MATERIALS AND METHODS

After the baseline characteristics were evaluated, 30 healthy volunteers were administrated with 3g of KRG for 10-16 days and diagnosed with "Shanghuo". The volunteers prior to the administration of KRG were considered as the control group. The volunteers after being diagnosed with "Shanghuo" (excessive heat) were considered as "Shanghuo" group. The two groups were assessed by the tests of serum metabolic products, Succinate Dehydrogenase (SDH) activity, and mRNA expressions of adenosine monophosphate (AMP)-activated protein kinase (AMPK), PPARG Coactivator 1 Alpha (PGC-1α) and Nuclear Respiratory Factor 1 (NRF1).

RESULTS

Most of the serum metabolites in the "Shanghuo" group were increased compared with the control group, from high to low including serine, valine, heptacosane, xylose, glycerol 1-monostearate, d-glucose, 3-pyridinol, glyceryl palmitate, urea, phosphoric acid, glycerol, stearic acid, palmitic acid, cyclohexaneacetic acid. Only cholesterol was significantly reduced, The SDH activity and the mRNA expressions of AMPK, PGC-1α and NRF1 were significantly increased in the "Shanghuo" group.

CONCLUSIONS

Overconsumption of KRG could induce "Shanghuo", which has a close relationship with an accelerated TCA cycle and the increased AMPK activity.

Activation of AMP-activated protein kinase during sepsis/inflammation improves survival by preserving cellular metabolic fitness

The purpose was to determine the role of AMPK activation in the renal metabolic response to sepsis, the development of sepsis-induced acute kidney injury (AKI) and on survival. In a prospective experimental study, 167 10- to 12-week-old C57BL/6 mice underwent cecal ligation and puncture (CLP) and human proximal tubule epithelial cells (TEC; HK2) were exposed to inflammatory mix (IM), a combination of lipopolysaccharide (LPS) and high mobility group box 1 (HMGB1). Renal/TEC metabolic fitness was assessed by monitoring the expression of drivers of oxidative phosphorylation (OXPHOS), the rates of utilization of OXPHOS/glycolysis in response to metabolic stress, and mitochondrial function by measuring O₂ consumption rates (OCR) and the membrane potential (Δψ_m ). Sepsis/IM resulted in AKI, increased mortality, and in renal AMPK activation 6-24 hours after CLP/IM. Pharmacologic activation of AMPK with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) or metformin during sepsis improved the survival, while AMPK inhibition with Compound C increased mortality, impaired mitochondrial respiration, decreased OCR, and disrupted TEC metabolic fitness. AMPK-driven protection was associated with increased Sirt 3 expression and restoration of metabolic fitness. Renal AMPK activation in response to sepsis/IM is an adaptive mechanism that protects TEC, organs, and the host by preserving mitochondrial function and metabolic fitness likely through Sirt3 signaling.

The Effect of Silibinin on Protein Expression Profile in White Adipose Tissue of Obese Mice

Objective

To investigate the effect of silibinin on the protein expression profile of white adipose tissue (WAT) in obese mice by using Tandem Mass Tag (TMT) and liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Methods

According to experimental requirements, 36 C57BL/6JC mice were randomly divided into normal diet group (WC group), high fat diet group (WF group), and high fat diet + silibinin group (WS group). WS group was intragastrically administered with 54 mg/kg body weight of silibinin, and the WC group and the WF group were intragastrically administered with equal volume of normal saline. Serum samples were collected to detect fasting blood glucose and blood lipids. IPGTT was used to measure the blood glucose value at each time point and calculate the area under the glucose curve. TMT combined with LC-MS/MS were used to study the expression of WAT, and its cellular processes, biological processes, corresponding molecular functions, and related network molecular mechanisms were analyzed by bioinformatics. Finally, RT-PCR and LC-MS/MS were used to detect the mRNA and protein expressions of FABP5, Plin4, GPD1, and AGPAT2, respectively.

Results

Although silibinin did not reduce the mice's weight, it did improve glucose metabolism. In addition, silibinin decreased the concentration of TC, TG, and LDL-C and increased the concentration of HDL-C in the serum of mice. In the WF/WS group, 182 differentially expressed proteins were up-regulated and 159 were down-regulated. While in the WS/WF group, 362 differentially expressed proteins were up-regulated and 176 were down-regulated. Further analysis found that these differential proteins are mainly distributed in the peroxisome proliferation-activated receptor (PPAR), lipolysis of fat cells, metabolism of glycerides, oxidative phosphorylation, and other signaling pathways, and participate in cell processes and lipid metabolism through catalysis and integration functions. Specifically, silibinin reduced the expression of several key factors such as FABP5, Plin4, GPD1, and AGPTA2.

Conclusion

High fat diet (HFD) can increase the expression of lipid synthesis and transport-related proteins and reduce mitochondrial related proteins, thereby increasing lipid synthesis, reducing energy consumption, and improving lipid metabolism in vivo. Silibinin can reduce lipid synthesis, increase energy consumption, and improve lipid metabolism in mice in vivo.

Andrographolide attenuates oxidative stress injury in cigarette smoke extract exposed macrophages through inhibiting SIRT1/ERK signaling

Andrographolide (AG), an ingredient extracted from traditional Chinese herbal medicine Andrographis paniculata, has been demonstrated to have potent anti-inflammatory and anti-oxidative stress properties. The purpose of this study was to investigate whether and how AG attenuated CSE-induced mitochondrial dysfunction, inflammation and oxidative stress in RAW 264.7 cells (a mouse macrophages line). The results showed that AG significantly reduced CSE-induced upregulation of pro-inflammatory cytokines (i.e., TNF-α and IL-1β) in the RAW 264.7 cells. AG inhibited CSE-induced production of reactive oxygen species (ROS) and prevented the reduction of superoxide dismutase (SOD) and glutathione/oxidized glutathione (GSH/GSSG) ratio, indicating the anti-oxidative stress effects of AG in macrophages. AG also improved mitochondrial function and mitochondrial membrane potential. In addition, AG inhibited CSE-induced increase of heme oxygenase (HO)-1, matrix metalloproteinase (MMP)-9 and MMP-12. Moreover, AG increased SIRT1 transcription and expression, suggesting AG inhibits mitochondrial dysfunction, inflammation and oxidative stress via a SIRT1 dependent signaling. We also demonstrated that AG inhibited CSE-induced ERK phosphorylation, and treatment with PD980589, a ERK inhibitor, reversed CSE-induced inflammation and oxidative stress. These results indicated that AG may prevent COPD via the inhibition of SIRT1/ERK signaling pathway, and subsequently inhibition of mitochondrial dysfunction, inflammation, and oxidative stress in macrophages.

Lipid-based nanodelivery approaches for dopamine-replacement therapies in Parkinson's disease: From preclinical to translational studies

The incidence of Parkinson's disease (PD), the second most common neurodegenerative disorder, has increased exponentially as the global population continues to age. Although the etiological factors contributing to PD remain uncertain, its average incidence rate is reported to be 1% of the global population older than 60 years. PD is primarily characterized by the progressive loss of dopaminergic (DAergic) neurons and/or associated neuronal networks and the subsequent depletion of dopamine (DA) levels in the brain. Thus, DA or levodopa (l-dopa), a precursor of DA, represent cardinal targets for both idiopathic and symptomatic PD therapeutics. While several therapeutic strategies have been investigated over the past decade for their abilities to curb the progression of PD, an effective cure for PD is currently unavailable. Even DA replacement therapy, an effective PD therapeutic strategy that provides an exogenous supply of DA or l-dopa, has been hindered by severe challenges, such as a poor capacity to bypass the blood-brain barrier and inadequate bioavailability. Nevertheless, with recent advances in nanotechnology, several drug delivery systems have been developed to bypass the barriers associated with central nervous system therapeutics. In here, we sought to describe the adapted lipid-based nanodrug delivery systems used in the field of PD therapeutics and their recent advances, with a particular focus placed on DA replacement therapies. This work initially explores the background of PD; offers descriptions of the most recent molecular targets; currently available clinical medications/limitations; an overview of several lipid-based PD nanotherapeutics, functionalized nanoparticles, and technical aspects in brain delivery; and, finally, presents future perspectives to enhance the use of nanotherapeutics in PD treatment.

Proinflammatory NFkB signalling promotes mitochondrial dysfunction in skeletal muscle in response to cellular fuel overloading

Sustained nutrient (fuel) excess, as occurs during obesity and diabetes, has been linked to increased inflammation, impaired mitochondrial homeostasis, lipotoxicity, and insulin resistance in skeletal muscle. Precisely how mitochondrial dysfunction is initiated and whether it contributes to insulin resistance in this tissue remains a poorly resolved issue. Herein, we examine the contribution that an increase in proinflammatory NFkB signalling makes towards regulation of mitochondrial bioenergetics, morphology, and dynamics and its impact upon insulin action in skeletal muscle cells subject to chronic fuel (glucose and palmitate) overloading. We show sustained nutrient excess of L6 myotubes promotes activation of the IKKβ-NFkB pathway (as judged by a six-fold increase in IL-6 mRNA expression; an NFkB target gene) and that this was associated with a marked reduction in mitochondrial respiratory capacity (>50%), a three-fold increase in mitochondrial fragmentation and 2.5-fold increase in mitophagy. Under these circumstances, we also noted a reduction in the mRNA and protein abundance of PGC1α and that of key mitochondrial components (SDHA, ANT-1, UCP3, and MFN2) as well as an increase in cellular ROS and impaired insulin action in myotubes. Strikingly, pharmacological or genetic repression of NFkB activity ameliorated disturbances in mitochondrial respiratory function/morphology, attenuated loss of SDHA, ANT-1, UCP3, and MFN2 and mitigated the increase in ROS and the associated reduction in myotube insulin sensitivity. Our findings indicate that sustained oversupply of metabolic fuel to skeletal muscle cells induces heightened NFkB signalling and that this serves as a critical driver for disturbances in mitochondrial function and morphology, redox status, and insulin signalling.

Mitochondrial Damage and Biogenesis in Acetaminophen-induced Liver Injury

Liver injury and acute liver failure caused by acetaminophen (APAP) overdose is the clinically most important drug toxicity in western countries. Mechanistic investigations have revealed a central role of mitochondria in the pathophysiology. Excess formation of the reactive metabolite N-acetyl-p-benzoquinone imine (NAPQI) after an overdose leads to hepatic glutathione depletion, mitochondrial protein adducts formation and an initial oxidant stress, which triggers the activation of mitogen activated protein (MAP) kinase cascade ultimately leading to c-jun N-terminal kinase (JNK) phosphorylation. Phospho-JNK translocates to the mitochondria and amplifies the oxidative and nitrosative stress eventually causing the mitochondrial membrane permeability transition pore opening and cessation of ATP synthesis. In addition, mitochondrial matrix swelling ruptures the outer membrane and releases endonucleases, which cause nuclear DNA fragmentation. Together, the nuclear DNA damage and the extensive mitochondrial dysfunction result in necrotic cell death. However, the pro-cell death signaling events are counteracted by adaptive responses such as autophagy and mitochondrial biogenesis. The improved mechanistic insight into the pathophysiology leads to better understanding of the mechanisms of action of the existing antidote N-acetylcysteine and justifies the clinical testing of novel therapeutics such as 4-methylpyrazole and calmangafodipir.

TLR4 signaling modulation of PGC1-α mediated mitochondrial biogenesis in the LPS-Chronic mild stress model: Effect of fluoxetine and pentoxiyfylline

AIM

The addition of repeated lipopolysaccharide (LPS) to chronic mild stress was recently proposed in our lab as an alternative model of depression, highlighting the possible interaction between stress and immune-inflammatory pathways in predisposing depression. Given that CMS-induced depressive behavior was previously related to impaired hippocampal energy metabolism and mitochondrial dysfunction, our current study aimed to investigate the interplay between toll-like receptor 4 (TLR4) signaling and peroxisome proliferator-activated receptor gamma coactivators-1-alpha (PGC1-α) as a physiological regulator of energy metabolism and mitochondrial biogenesis in the combined LPS/CMS model.

MAIN METHODS

Male Wistar rats were exposed to either LPS (50 μg/kg i.p.) over 2 weeks, CMS protocol for 4 weeks or LPS over 2 weeks followed by 4 weeks of CMS (LPS/CMS). Three additional groups of rats were exposed to LPS/CMS protocol and treated with either pentoxifylline (PTX), fluoxetine (FLX) or a combination of both. Rats were examined for behavioral, neurochemical, gene expression and mitochondrial ultra-structural changes.

KEY FINDINGS

LPS/CMS increased the expression of TLR4 and its downstream players; MyD88, NFκB and TNF-α along with an escalation in hippocampal-energy metabolism and p-AMPK. Simultaneously LPS/CMS attenuated the expression of PGC1-α/NRF1/Tfam and mt-DNA. The antidepressant (AD) 'FLX', the TNF-α inhibitor 'PTX' and their combination ameliorated the LPS/CMS-induced changes. Interestingly, all the aforementioned changes induced by the LPS/CMS combined model were significantly less than those induced by CMS alone.

SIGNIFICANCE

Blocking the TLR4/NFκB signaling enhanced the activation of the PGC1-α/NRF1/Tfam and mt-DNA content independent on the activation of the energy-sensing kinase AMPK.

Role of mitochondrial depolarization and disrupted mitochondrial homeostasis in non-alcoholic steatohepatitis and fibrosis in mice

The pathogenesis of non-alcoholic steatohepatitis (NASH) is poorly understood. Here, relationships between mitochondrial depolarization (mtDepo) and mitochondrial homeostasis were studied in a mouse model of NASH. C57BL/6 mice were fed a Western diet (high fat, fructose and cholesterol) for 2 weeks, 2 months and 6 months, and livers were harvested for histology and biochemical analysis. Hepatic mtDepo was evaluated by intravital multiphoton microscopy. After Western diet feeding, mixed hepatic micro- and macrovesicular steatosis and leukocyte infiltration occurred at 2 weeks and continued to increase afterwards. ALT release, mild necrosis, apoptosis, and ballooning degeneration were present at 2 and 6 months. Smooth muscle α-actin expression increased at 2 weeks and longer, and increased collagen-I expression and mild fibrosis occurred at 6 months. After feeding Western diet for 2 weeks and longer, mtDepo appeared in 50-70% hepatocytes, indicating mitochondrial dysfunction at an early stage of NASH. mtDepo can initiate mitophagy, and mitophagic markers increased at 2 and 6 months. Concurrently autophagic processing became impaired. Oxidative phosphorylation proteins, mitochondrial biogenesis signals, and proteins associated with mitochondrial fission and fusion decreased after 2 months and longer of Western diet. Proinflammatory and profibrotic signaling (NLRP3 inflammasome activation, expression of IL-1, osteopontin and TGF-β1) also increased in association with mitochondrial stress/dysfunction after Western diet feeding. Taken together, we show that hepatic mtDepo occurs early in mice fed a Western diet, followed by increased mitophagic burden, suppressed mitochondrial biogenesis and dynamics, and mitochondrial depletion. These novel mitochondrial alterations in NASH most likely play an important role in promoting steatosis, inflammation, and progression to fibrosis.

Mitochondrial Dysfunction in Cardiac Surgery

Mitochondria are key to the cellular response to energetic demand, but are also vital to reactive oxygen species signaling, calcium hemostasis, and regulation of cell death. Cardiac surgical patients with diabetes, heart failure, advanced age, or cardiomyopathies may have underlying mitochondrial dysfunction or be more sensitive to perioperative mitochondrial injury. Mitochondrial dysfunction, due to ischemia/reperfusion injury and an increased systemic inflammatory response due to exposure to cardiopulmonary bypass and surgical tissue trauma, impacts myocardial contractility and predisposes to arrhythmias. Strategies for perioperative mitochondrial protection and recovery include both well-established cardioprotective protocols and targeted therapies that remain under investigation.

Towards a personalised approach in exercise-based cardiovascular rehabilitation: How can translational research help? A 'call to action' from the Section on Secondary Prevention and Cardiac Rehabilitation of the European Association of Preventive Cardiology

The benefit of regular physical activity and exercise training for the prevention of cardiovascular and metabolic diseases is undisputed. Many molecular mechanisms mediating exercise effects have been deciphered. Personalised exercise prescription can help patients in achieving their individual greatest benefit from an exercise-based cardiovascular rehabilitation programme. Yet, we still struggle to provide truly personalised exercise prescriptions to our patients. In this position paper, we address novel basic and translational research concepts that can help us understand the principles underlying the inter-individual differences in the response to exercise, and identify early on who would most likely benefit from which exercise intervention. This includes hereditary, non-hereditary and sex-specific concepts. Recent insights have helped us to take on a more holistic view, integrating exercise-mediated molecular mechanisms with those influenced by metabolism and immunity. Unfortunately, while the outline is recognisable, many details are still lacking to turn the understanding of a concept into a roadmap ready to be used in clinical routine. This position paper therefore also investigates perspectives on how the advent of 'big data' and the use of animal models could help unravel inter-individual responses to exercise parameters and thus influence hypothesis-building for translational research in exercise-based cardiovascular rehabilitation.

EPA and DHA elicit distinct transcriptional responses to high-fat feeding in skeletal muscle and liver

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) exert numerous beneficial biological effects and attenuate diet-induced insulin resistance in rodent models. In the present study, the independent, tissue-specific effects of two nutritionally relevant n-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were characterized in the context of a high-fat diet (HFD). EPA and DHA supplementation (3.2% of total fat) in 6-mo-old male C57BL/6 mice fed an HFD (60% fat) partially mitigated reductions in insulin sensitivity. At 5 wk, the area above the curve below baseline glucose following an intraperitoneal insulin tolerance test was 54.5% lower in HFD than control, whereas HFD + EPA and HFD + DHA showed 27.6% and 17.1% reductions, respectively. At 10 wk, HFD increased mitochondrial oxidative capacity supported by lipid and carbohydrate-based substrates in both liver and skeletal muscle (P < 0.05), with little effect of EPA or DHA supplementation. Whole genome transcriptomic analyses revealed HFD-induced transcriptional changes indicative of inflammation and fibrosis in both liver and muscle. Gene set enrichment analyses indicated a downregulation of transcripts associated with extracellular matrix in muscle (family-wise error rate P < 0.01) and liver (P = 0.04) and in transcripts associated with inflammation in muscle (P = 0.03) in HFD + DHA compared with HFD alone. In contrast, EPA appeared to potentiate some proinflammatory effects of the HFD. In the skeletal muscle, DHA increased the expression of stress-responsive genes, whereas EPA upregulated the expression of transcripts related to cell cycle. Therefore, although both EPA and DHA supplementation during HFD partially preserve insulin signaling, they modulate distinct processes, highlighting their unique biological effects in the context of obesity.

The Evolving Erythrocyte: Red Blood Cells as Modulators of Innate Immunity

The field of red cell biology is undergoing a quiet revolution. Long assumed to be inert oxygen carriers, RBCs are emerging as important modulators of the innate immune response. Erythrocytes bind and scavenge chemokines, nucleic acids, and pathogens in circulation. Depending on the conditions of the microenvironment, erythrocytes may either promote immune activation or maintain immune quiescence. We examine erythrocyte immune function through a comparative and evolutionary lens, as this framework may offer perspective into newly recognized roles of human RBCs. Next, we review the known immune roles of human RBCs and discuss their activity in the context of sepsis where erythrocyte function may prove important to disease pathogenesis. Given the limited success of immunomodulatory therapies in treating inflammatory diseases, we propose that the immunologic function of RBCs provides an understudied and potentially rich area of research that may yield novel insights into mechanisms of immune regulation.

In vitro effect of globotriaosylceramide on electron transport chain complexes and redox parameters

Fabry disease (FD) is an X-linked inherited disease and occurs due to mutations in GLA gene that encodes the α-galactosidase enzyme. Consequently, there is an accumulation of enzyme substrates, namely globotriaosylceramide (GB3). FD is a multisystemic disease, caused by storage of GB3 in vascular endothelia, with significant renal, cardiac and vascular involvement. The aim of this work was to evaluate the in vitro effect of GB3 on electron transport chain complexes (ETC) and redox parameters. Biochemical biomarkers were determined in homogenates of cerebral cortex, kidneys and liver of Wistar rats in the presence or absence of GB3 at concentrations of 3, 6, 9 and 12 mg/L. We found that GB3 caused an increase of ETC complexes II and IV activities, increased production of reactive species and decreased superoxide dismutase enzyme activity in homogenates of cerebral cortex. As well also increased production of reactive species and superoxide dismutase activity in kidney homogenates. The results obtained in our work suggest that GB3 interferes in ETC complexes II and IV activities, however, the magnitude of this increase seems to be too low to present a physiologically importance. However, the imbalance in cellular redox state indicating that these alterations may be involved in the pathophysiology of FD, mainly in renal and cerebral manifestations.

Understanding the Metabolic Profile of Macrophages During the Regenerative Process in Zebrafish

In contrast to mammals, lower vertebrates, including zebrafish (Danio rerio), have the ability to regenerate damaged or lost tissues, such as the caudal fin, which makes them an ideal model for tissue and organ regeneration studies. Since several diseases involve the process of transition between fibrosis and tissue regeneration, it is necessary to attain a better understanding of these processes. It is known that the cells of the immune system, especially macrophages, play essential roles in regeneration by participating in the removal of cellular debris, release of pro- and anti-inflammatory factors, remodeling of components of the extracellular matrix and alteration of oxidative patterns during proliferation and angiogenesis. Immune cells undergo phenotypical and functional alterations throughout the healing process due to growth factors and cytokines that are produced in the tissue microenvironment. However, some aspects of the molecular mechanisms through which macrophages orchestrate the formation and regeneration of the blastema remain unclear. In the present review, we outline how macrophages orchestrate the regenerative process in zebrafish and give special attention to the redox balance in the context of tail regeneration.

Oxidative stress induced by self-adhesive resin cements affects gene expression, cellular proliferation and mineralization potential of the MDPC-23 odontoblast-like cells

OBJECTIVE

Clinical issues have been raised about problems related to cytotoxic effects caused when applying self-adhesive cement. It was hypothesized that byproducts eluted from self-adhesive cements modulate oxidative stress response, the gene expression of signaling pathways of inflammatory process/transcriptional activators, and the expression and activity of interstitial collagenases, and modify the phenotypic characteristics of cellular proliferation and mineral deposition in odontoblastic-like cells.

METHODS

Cements (MaxCem Elite [MAX] and RelyX U200 [U200)]) were mixed, dispensed into moulds, and photoactivated according to the manufacturers' instructions. Immortalized rat odontoblast-like cells (MDPC-23) were cultured and exposed to polymerized specimens of cements for 4 h. Reactive oxidative specimen production and quantification of gene expression were evaluated. Cell proliferation assay and alizarin red staining were also performed to evaluate the disturbance induced by the cements on cellular proliferation and mineralization.

RESULTS

Despite their cytotoxic effects, both self-adhesive cements influenced the metabolism in the odontoblast cells on different scales. MAX induced significantly higher oxidative stress in odontoblast cells than U200. Gene expression varied as a function of exposure to self-adhesive cements; MAX induced the expression of pro-inflammatory cytokines such as TNF-α, whereas U200 downregulated, virtually depleted TNF-α expression, also inducing overexpression of the transcriptional factor Runx2. Overexpression of heme oxygenase-1 (HO-1) and thioredoxin reductase 1 (TRXR1) occurred after exposure to both cements, antioxidant genes that are downstream of Keap1-Nrf2-ARE system. MAX significantly induced the overexpression of collagenase MMP-1, and U200 induced the expression of gelatinase MMP-2. MAX significantly inhibited cell proliferation whereas U200 significantly activated cell proliferation. Alizarin red staining revealed significantly decreased mineral deposition especially when exposed to MAX.

SIGNIFICANCE

These results support the hypothesis that byproducts of different self-adhesive cements play important roles in the highly orchestrated process which ultimately affect the cellular proliferation and the mineral deposition in odontoblastic-like cells, possibly delaying the reparative dentin formation after cementation of indirect restorations, especially on recently exposed dentin preparations.

Resveratrol decreases the expression of genes involved in inflammation through transcriptional regulation

Oxidative stress generated during inflammation is associated with a wide range of pathologies. Resveratrol (RESV) displays anti-inflammatory and antioxidant activities, being a candidate for the development of adjuvant therapies for several inflammatory diseases. Despite this potential, the cellular responses induced by RESV are not well known. In this work, transcriptomic analysis was performed following lipopolysaccharide (LPS) stimulation of monocyte cultures in the presence of RESV. Induction of an inflammatory response was observed after LPS treatment and the addition of RESV led to decreases in expression of the inflammatory mediators, tumor necrosis factor-alpha (TNF-α), interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1), without cytotoxicity. RNA sequencing revealed 823 upregulated and 2098 downregulated genes (cutoff ≥2.0 or ≤-2.0) after RESV treatment. Gene ontology analysis showed that the upregulated genes were associated with metabolic processes and the cell cycle, consistent with normal cell growth and differentiation under an inflammatory stimulus. The downregulated genes were associated with inflammatory responses, gene expression, and protein modification. The prediction of master regulators using the iRegulon tool showed nuclear respiratory factor 1 (NRF1) and GA-binding protein alpha subunit (GABPA) as the main regulators of the downregulated genes. Using immunoprecipitation and protein expression assays, we observed that RESV was able to decrease protein acetylation patterns, such as acetylated apurinic/apyrimidinic endonuclease-1/reduction-oxidation factor 1 (APE1/Ref-1), and increase histone methylation. In addition, reductions in p65 (nuclear factor-kappa B (NF-κB) subunit) and lysine-specific histone demethylase-1 (LSD1) expression were observed. In conclusion, our data indicate that treatment with RESV caused significant changes in protein acetylation and methylation patterns, suggesting the induction of deacetylase and reduction of demethylase activities that mainly affect regulatory cascades mediated by NF-кB and Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling. NRF1 and GABPA seem to be the main regulators of the transcriptional profile observed after RESV treatment.

1,25-Dihydroxyvitamin D3 modulates the effects of sublethal BPA on mitochondrial function via activating PI3K-Akt pathway and 17β-estradiol secretion in rat granulosa cells

Bisphenol A (BPA), an endocrine-disrupting chemical, is capable of producing reproductive toxicity. BPA results in mitochondrial DNA (mtDNA) deletion and mitochondrial dysfunction; however, the effect of BPA on the mitochondria of ovarian granulosa cells is not clear. Further, 1,25-dihydroxyvitamin D₃ (1,25D₃) may play a role in reproduction, because its receptor, VDR, contributes to the inhibition of oxidative stress and predominantly exists in the nuclei of granulosa cells. Hence, the role of 1,25D₃ in BPA-mediated effects on mitochondrial function was examined in this study. Primary rat granulosa cells treated with BPA, 1,25D₃, or both were subjected to molecular/biochemical assays to measure cell survival, mtDNA content, mtDNA deletion, superoxide dismutase activity, levels of proteins related to mitochondrial biogenesis, and mitochondrial function. We found that cell viability was dose-dependently reduced and reactive oxygen species (ROS) levels were increased by BPA treatment. BPA administration elevated Mn-superoxide dismutase (MnSOD) expression but negatively regulated total SOD activity. 1,25D₃ treatment alone increased 17β-estradiol secretion, ATP production, and cellular oxygen consumption. In cells treated with both agents, 1,25D₃ enhanced BPA-induced MnSOD protein upregulation and blocked the BPA-mediated decline in total SOD activity. Furthermore, 1,25D₃ attenuated BPA-mediated mtDNA deletion but showed no effect on BPA-induced increases in mtDNA content. Although BPA had no influence on the levels of peroxisome proliferator-activated receptor-γ coactivator-1 α, nuclear respiratory factor-1, mitochondrial transcription factor A, or cytochrome c oxidase subunit IV, 1,25D₃ plus BPA markedly increased mitochondrial biogenesis-related protein expression via the PI3K-Akt pathway. Moreover, BPA-mediated negative regulation of cytochrome c oxidase subunit I levels and 17β-estradiol secretion was attenuated by 1,25D₃ pre-treatment. Our results suggest that 1,25D₃ attenuates BPA-induced decreases in 17β-estradiol and that treatment with 1,25D₃ plus BPA regulates granulosa cell mitochondria by elevating mitochondrial biogenesis-related protein levels.

Amplification of Mitochondrial Activity in the Healing Response Following Rotator Cuff Tendon Injury

Mitochondrial function following rotator cuff tendon injury (RCI) influences the tendon healing. We examined the mitochondrial morphology and function under hypoxia in the shoulder tendon tissue from surgically-induced tenotomy-RCI rat model and cultured swine tenocytes. The tendon tissue was collected post-injury on 3-5 (Group-A), 10-12 (Group-B), and 22-24 (Group-C), days and the corresponding contralateral tendons were used as control for each group. There was higher protein expression of citrate synthase (P < 0.0001) [10.22 MFI (mean fluorescent intensity)] and complex-1 (P = 0.0008) (7.86 MFI) in Group-A and Group-B that decreased in Group-C [(P = 0.0201) (5.78 MFI and (P = 0.7915) (2.32 MFI), respectively] compared to control tendons. The ratio of BAX:Bcl2 (Bcl2 associated x protein:B cell lymphoma 2) in RCI tendons increased by 50.5% (Group-A) and 68.4% (Group-B) and decreased by 25.8% (Group-C) compared to normoxic controls. Hypoxia increased β-tubulin expression (P = 0067) and reduced PGC1-α (P = 0412) expression in the isolated swine tenocytes with no effect on the protein expression of Complex-1 (P = 7409) and citrate synthase (P = 0.3290). Also, the hypoxic tenocytes exhibited about 4-fold increase in mitochondrial superoxide (P < 0.0001), altered morphology and mitochondrial pore integrity, and increase in mitochondrial density compared to normoxic controls. These findings suggest the critical role of mitochondria in the RCI healing response.

Activation of mammalian terget of rapamycin kinase and glycogen synthase kinase-3β accompanies abnormal accumulation of cholesterol in fibroblasts from Niemann-Pick type C patients

BACKGROUND

Niemann Pick type C (NPC) lysosomal disorder is linked to the disruption of cholesterol transport. Recent data suggest that the molecular background of this disease is more complex. It was found that accumulation of cholesterol and glycolipids in the late endosomal/lysosomal compartment of NPC1 cells may affect mitochondrial functions.

MATERIALS AND METHODS

In this study, primary skin fibroblasts derived from skin biopsies of two anonymous patients with NPC-carrying mutations in the NPC1 gene, characterized by a high total cholesterol content, as well as two healthy donors were used. The presence of signaling proteins in the whole cell lysates and mitochondrial fractions were examined by Western blotting assay.

RESULTS

In this report, we provide experimental evidence that in NPC1 cells, dysfunction of mitochondria and cellular metabolism, as reported by Wos et al in 2016, coexist with alterations in signal transduction pathways, such as the mammalian target of rapamycin, AKT, phosphoinositide-dependent protein kinase-1, glycogen synthase kinase-3 β, and Jun amino-terminal kinase, leading to abnormal cholesterol accumulation and distribution.

CONCLUSION

Differences in signal transduction between control and NPC1 cells may suggest that the latter cells experienced significant alterations in the complex molecular mechanisms that control cellular energy metabolism and vesicular transport.

Bioactive food and exercise in chronic kidney disease: Targeting the mitochondria

Chronic kidney disease (CKD), which affects 10%-15% of the population, associates with a range of complications-such as cardiovascular disease, frailty, infections, muscle and bone disorders and premature ageing-that could be related to alterations of mitochondrial number, distribution, structure and function. As mitochondrial biogenesis, bioenergetics and the dynamic mitochondrial networks directly or indirectly regulate numerous intra- and extracellular functions, the mitochondria have emerged as an important target for interventions aiming at preventing or improving the treatment of complications in CKD. In this review, we discuss the possible role of bioactive food compounds and exercise in the modulation of the disturbed mitochondrial function in a uraemic milieu.

Metabolomics of Ndufs4-/- skeletal muscle: Adaptive mechanisms converge at the ubiquinone-cycle

Leigh syndrome is one of the most common childhood-onset neurometabolic disorders resulting from a primary oxidative phosphorylation dysfunction and affecting mostly brain tissues. Ndufs4^-/- mice have been widely used to study the neurological responses in this syndrome, however the reason why these animals do not display strong muscle involvement remains elusive. We combined biochemical strategies and multi-platform metabolomics to gain insight into the metabolism of both glycolytic (white quadriceps) and oxidative (soleus) skeletal muscles from Ndufs4^-/- mice. Enzyme assays confirmed severely reduced (80%) CI activity in both Ndufs4^-/- muscle types, compared to WTs. No significant alterations were evident in other respiratory chain enzyme activities; however, Ndufs4^-/- solei displayed moderate decreases in citrate synthase (12%) and CIII (18%) activities. Through hypothesis-generating metabolic profiling, we provide the first evidence of adaptive responses to CI dysfunction involving non-classical pathways fueling the ubiquinone (Q) cycle. We report a respective 48 and 34 discriminatory metabolites between Ndufs4^-/- and WT white quadriceps and soleus muscles, among which the most prominent alterations indicate the involvement of the glycerol-3-phosphate shuttle, electron transfer flavoprotein system, CII, and proline cycle in fueling the Q cycle. By restoring the electron flux to CIII via the Q cycle, these adaptive mechanisms could maintain adequate oxidative ATP production, despite CI deficiency. Taken together, our results shed light on the underlying pathogenic mechanisms of CI dysfunction in skeletal muscle. Upon further investigation, these pathways could provide novel targets for therapeutic intervention in CI deficiency and potentially lead to the development of new treatment strategies.

Cystathionine-γ-lyase expression is associated with mitochondrial respiration during sepsis-induced acute kidney injury in swine with atherosclerosis

Background

Sepsis is associated with disturbed glucose metabolism and reduced mitochondrial activity and biogenesis, ultimately leading to multiple organ dysfunction, e.g., acute kidney injury (AKI). Cystathionine-γ-lyase (CSE), the major cardiovascular source of endogenous H₂S release, is implicated in the regulation of glucose metabolism and mitochondrial activity through a PGC1α-dependent mechanism, and critical for kidney function. Atherosclerosis is associated with mitochondrial dysfunction and reduced CSE expression. Thus, the aim of this post hoc study was to test the hypothesis whether there is an interplay between CSE expression and kidney dysfunction, mitochondrial activity, and oxidative/nitrosative stress in porcine septic AKI with underlying coronary artery disease.

Methods

This study is a post hoc analysis of material from anesthetized and instrumented swine with a high fat diet-induced hypercholesterolemia and atherosclerosis undergoing faecal peritonitis-induced septic shock or sham procedure and intensive care (comprising fluid resuscitation and continuous i.v. noradrenaline (NoA) infusion) for 24 h. Glucose metabolism was quantified from blood ¹³C₆-glucose and expiratory ¹³CO₂/¹²CO₂ isotope enrichment during ¹³C₆-glucose infusion. Mitochondrial activity was determined by high-resolution respirometry. CSE and PGC1α expression, as well as nitrotyrosine formation and albumin extravasation, were quantified by immunohistochemistry of formalin-fixed kidney paraffin sections.

Results

Sepsis was associated with lactic acidosis (p = 0.004) and AKI (50% fall of creatinine clearance (CrCl), p = 0.019). While both whole-body glucose production (p = 0.004) and oxidation (p = 0.006) were increased, kidney tissue mitochondrial respiration was reduced (p = 0.028), coinciding with decreased CSE (p = 0.003) and PGC1α (p = 0.003) expression. Albumin extravasation (p = 0.011) and nitrotyrosine formation (p = 0.008) were increased in septic kidneys.

Conclusions

Sepsis-induced AKI is associated with disturbed mitochondrial respiration and biogenesis, which may be aggravated by oxidative and nitrosative stress. Our results confirm previous data in murine septic shock and porcine hemorrhage and resuscitation on the crucial role of CSE for barrier integrity and kidney function.

Electronic supplementary material

The online version of this article (10.1186/s40635-018-0208-z) contains supplementary material, which is available to authorized users.

Beclin-1 regulates cigarette smoke-induced kidney injury in a murine model of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), associated with cigarette smoke-induced (CS-induced) emphysema, contributes significantly to the global health care burden of disease. Although chronic kidney disease (CKD) may occur in patients with COPD, the relationship between COPD and CKD remains unclear. Using a murine model of experimental COPD, we show that chronic CS exposure resulted in marked kidney injury and fibrosis, as evidenced by histological and ultrastructural changes, altered macrophage subpopulations, and expression of tissue injury, fibrosis, and oxidative stress markers. CS induced mitochondrial dysfunction, and increased autophagic flux in kidney tissues and in kidney tubular epithelial (HK-2) cells, as determined by LC3B turnover assays. Mice heterozygous for Beclin-1 (Becn1+/-) were protected from the development of kidney tissue injury and renal fibrosis in response to CS exposure, and displayed impaired basal and inducible mitochondrial turnover by mitophagy. Interestingly, CS caused a reduction of Beclin-1 expression in mouse kidneys and kidney tubular epithelial cells, attributed to increased autophagy-dependent turnover of Beclin-1. These results suggest that Beclin-1 is required for CS-induced kidney injury and that reduced levels of Beclin-1 may confer renoprotection. These results identify the kidney as a target for CS-induced injury in COPD and the Beclin-1-dependent autophagy pathway as a potential therapeutic target in CKD.

PGC-1α Protects RPE Cells of the Aging Retina against Oxidative Stress-Induced Degeneration through the Regulation of Senescence and Mitochondrial Quality Control. The Significance for AMD Pathogenesis

PGC-1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha) is a transcriptional coactivator of many genes involved in energy management and mitochondrial biogenesis. PGC-1α expression is associated with cellular senescence, organismal aging, and many age-related diseases, including AMD (age-related macular degeneration), an important global issue concerning vision loss. We and others have developed a model of AMD pathogenesis, in which stress-induced senescence of retinal pigment epithelium (RPE) cells leads to AMD-related pathological changes. PGC-1α can decrease oxidative stress, a key factor of AMD pathogenesis related to senescence, through upregulation of antioxidant enzymes and DNA damage response. PGC-1α is an important regulator of VEGF (vascular endothelial growth factor), which is targeted in the therapy of wet AMD, the most devastating form of AMD. Dysfunction of mitochondria induces cellular senescence associated with AMD pathogenesis. PGC-1α can improve mitochondrial biogenesis and negatively regulate senescence, although this function of PGC-1α in AMD needs further studies. Post-translational modifications of PGC-1α by AMPK (AMP kinase) and SIRT1 (sirtuin 1) are crucial for its activation and important in AMD pathogenesis.

Mitochondrial fidelity and metabolic agility control immune cell fate and function

Remodeling of mitochondrial metabolism plays an important role in regulating immune cell fate, proliferation, and activity. Furthermore, given their bacterial ancestry, disruption in mitochondrial fidelity leading to extravasation of their content initiates and amplifies innate immune surveillance with a myriad of physiologic and pathologic consequences. Investigations into the role of mitochondria in the immune system have come to the fore, and appreciation of mitochondrial function and quality control in immune regulation has enhanced our understanding of disease pathogenesis and identified new targets for immune modulation. This mitochondria-centered Review focuses on the role of mitochondrial metabolism and fidelity, as well as the role of the mitochondria as a structural platform, for the control of immune cell polarity, activation, and signaling. Mitochondria-linked disease and mitochondrially targeted therapeutic strategies to manage these conditions are also discussed.