Mitochondrial quality control mechanisms as potential therapeutic targets in sepsis-induced multiple organ failure.
TL;DR: This review will focus on advances concerning potential mechanisms in regulating mitochondria quality control and impacts of mitochondrial quality control on the progression of sepsis.
Abstract: Sepsis is a dysregulated response to severe infection characterized by life-threatening organ failure and is the leading cause of mortality worldwide. Multiple organ failure is the central characteristic of sepsis and is associated with poor outcome of septic patients. Ultrastructural damage to the mitochondria and mitochondrial dysfunction are reported in sepsis. Mitochondrial dysfunction with subsequent ATP deficiency, excessive reactive oxygen species (ROS) release, and cytochrome c release are all considered to contribute to organ failure. Consistent mitochondrial dysfunction leads to reduced mitochondrial quality control capacity, which eliminates dysfunctional and superfluous mitochondria to maintain mitochondrial homeostasis. Mitochondrial quality is controlled through a series of processes including mitochondrial biogenesis, mitochondrial dynamics, mitophagy, and transport processes. Several studies have indicated that multiple organ failure is ameliorated by restoring mitochondrial quality control mechanisms and is further amplified by defective quality control mechanisms. This review will focus on advances concerning potential mechanisms in regulating mitochondrial quality control and impacts of mitochondrial quality control on the progression of sepsis.
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TL;DR: The present state of research on targeted therapeutic drugs is elaborated upon to provide information for the treatment of sepsis and the recent development in understanding regarding the cellular pathogenesis and the target of clinical diagnosis is reviewed.
Abstract: Sepsis is defined as “a life-threatening organ dysfunction caused by a host’s dysfunctional response to infection”. Although the treatment of sepsis has developed rapidly in the past few years, sepsis incidence and mortality in clinical treatment is still climbing. Moreover, because of the diverse manifestations of sepsis, clinicians continue to face severe challenges in the diagnosis, treatment, and management of patients with sepsis. Here, we review the recent development in our understanding regarding the cellular pathogenesis and the target of clinical diagnosis of sepsis, with the goal of enhancing the current understanding of sepsis. The present state of research on targeted therapeutic drugs is also elaborated upon to provide information for the treatment of sepsis.
249 citations
Cites background from "Mitochondrial quality control mecha..."
...Mitochondrial biogenesis is regulated by the AMPK/PGC-1α/NRF-1/2 signaling pathway; nevertheless, the disproportionality of the ATP/ADP ratio as a result of insufficient ATP production disrupts the activation of AMPK and the subsequent PGC-1α/NRF-1/2 pathway and thereby contributes to TFAM expression [53,54]....
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23 Oct 2015
TL;DR: Hedeflenen kaloriye ulaşılması ile protein katabolizması ve malnutrisyonun iyileştirilmesi ve bununla ilişkili morbidite ve mortalitede azalma amaçlanmaktadır bakımında önemlidir.
Abstract: Beslenme desteği kritik yetişkin hastaların bakımında önemlidir. Fakat kritik hasta için uygun kalori hedefi net değildir. Hedeflenen kaloriye ulaşılması ile protein katabolizması ve malnutrisyonun iyileştirilmesi ve bununla ilişkili morbidite ve mortalitede azalma amaçlanmaktadır. Farklı kalori miktarına sahip enteral beslenme alımını inceleyen gözlemsel çalışmalar çelişkili sonuçlar ortaya koymuştur. Kritik hastalarda rutin enteral beslenme ile yüksek kalorili enteral beslenmeyi karşılaştıran iki randomize kontrollü çalışma (RKÇ) yüksek kalorili enteral beslenme ile mortalitede bir azalma göstermemiştir. Akut akciğer hasarı veya akut solunum yetmezlikli kritik hastalarda yapılan iki RKÇ mimimum ya da trofik enteral beslenme ile (hedeflenen kalorinin %15-25) standart enteral beslenmede (SEB) benzer sonuçlar göstermiştir. Mevcut kanıtlar erken kritik hastalık sırasında eş zamanlı kalori alımına bakılmaksızın belli bir düzeyde protein alımını desteklemesine rağmen protein dışı enerji kısıtlaması yapılan hastalarda protein ihtiyacının tamamının yerine konmasının sonuçlar üzerine etkisi bilinmemektedir. Sıçanlarda yapılan bir çalışma, glukoz verilmeden protein ile beslenmenin malnutrisyon ile azalmış olan mitokondriyal fonksiyonlarda düzelme sağladığını göstermiştir. Bu nedenle diyetle yeterli protein alımı sağlanırsa kalori kısıtlamasının yararlı olabileceği öne sürülmüştür. Bu çalışmanın hipotezi protein alımı korunurken protein dışı kalori kısıtlaması (permisif hipokalorik beslenme) yapılan kritik erişkin hastalarda, standart beslenme alan hastalara göre 90 günlük sağ kalımın daha iyi olduğunun gösterilmesidir.
191 citations
TL;DR: The effects of mitochondrial dynamics, mitophagic flux and Nrf2 signalling on the mitochondrial quality control, ROS production and NP cell survival in in vitro and ex vivo compression models of IDD are evaluated and the effects of the mitochondria‐targeted anti‐oxidant MitoQ and its mechanism explored.
Abstract: Objective Mitochondrial dysfunction, oxidative stress and nucleus pulposus (NP) cell apoptosis are important contributors to the development and pathogenesis of intervertebral disc degeneration (IDD). Here, we comprehensively evaluated the effects of mitochondrial dynamics, mitophagic flux and Nrf2 signalling on the mitochondrial quality control, ROS production and NP cell survival in in vitro and ex vivo compression models of IDD and explored the effects of the mitochondria-targeted anti-oxidant MitoQ and its mechanism. Material and methods Human NP cells were exposed to mechanical compression to mimic pathological conditions. Results Compression promoted oxidative stress, mitochondrial dysfunction and NP cell apoptosis. Mechanistically, compression disrupted the mitochondrial fission/fusion balance, inducing fatal fission. Concomitantly, PINK1/Parkin-mediated mitophagy was activated, whereas mitophagic flux was blocked. Nrf2 anti-oxidant pathway was insufficiently activated. These caused the damaged mitochondria accumulation and persistent oxidative damage. Moreover, MitoQ restored the mitochondrial dynamics balance, alleviated the impairment of mitophagosome-lysosome fusion and lysosomal function and enhanced the Nrf2 activity. Consequently, damaged mitochondria were eliminated, redox balance was improved, and cell survival increased. Additionally, MitoQ alleviated IDD in an ex vivo rat compression model. Conclusions These findings suggest that comodulation of mitochondrial dynamics, mitophagic flux and Nrf2 signalling alleviates sustained mitochondrial dysfunction and oxidative stress and represents a promising therapeutic strategy for IDD; furthermore, our results provide evidence that MitoQ might serve as an effective therapeutic agent for this disorder.
73 citations
TL;DR: A novel mechanism in which DEX protects against LPS-induced AKI is demonstrated, which results in the removal of damaged mitochondria and reduces oxidative stress and apoptosis in L PS- induced AKI through the α2-AR and inhibition of the PI3K/AKT/mTOR pathway.
Abstract: Background Acute kidney injury (AKI) is often secondary to sepsis. Previous studies suggest that damaged mitochondria and the inhibition of autophagy results in AKI during sepsis, but dexmedetomidine (DEX) alleviates lipopolysaccharide (LPS)-induced AKI. However, it is uncertain whether the renoprotection of DEX is related to autophagy or the clearance of damaged mitochondria in sepsis-induced AKI. Methods In this study, AKI was induced in rats by injecting 10 mg/kg of LPS intraperitoneally (i.p.). The rats were also pretreated with DEX (30 μg/kg, i.p.) 30 min before the injection of LPS. The structure and function of kidneys harvested from the rats were evaluated, and the protein levels of autophagy-related proteins, oxidative stress levels, and apoptosis levels were measured. Further, atipamezole (Atip) and 3-Methyladenine (3-MA), which are inhibitors of DEX and autophagy, respectively, were administered before the injection of DEX to examine the protective mechanism of DEX. Results Pretreatment with DEX ameliorated kidney structure and function. DEX decreased the levels of blood urea nitrogen (BUN) and creatinine (Cre), urine kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), reactive oxygen species (ROS), and apoptosis proteins (such as cleaved caspase-9 and cleaved caspase-3). However, DEX upregulated the levels of autophagy and mitophagy proteins, such as Beclin-1, LC3 II and PINK1. These results suggest that DEX ameliorated LPS-induced AKI by reducing oxidative stress and apoptosis and enhancing autophagy. To promote autophagy, DEX inhibited the phosphorylation levels of PI3K, AKT, and mTOR. Furthermore, the administration of Atip and 3-MA inhibitors blocked the renoprotection effects of DEX. Conclusions Here, we demonstrate a novel mechanism in which DEX protects against LPS-induced AKI. DEX enhances autophagy, which results in the removal of damaged mitochondria and reduces oxidative stress and apoptosis in LPS-induced AKI through the α2-AR and inhibition of the PI3K/AKT/mTOR pathway.
70 citations
TL;DR: In this paper, the authors investigated whether DEX afforded lung protection by regulating the process of mitochondrial dynamics through the HIF-1a/HO-1 pathway in vivo and in vitro.
Abstract: Increasing lines of evidence identified that dexmedetomidine (DEX) exerted protective effects against sepsis-stimulated acute lung injury via anti-inflammation, anti-oxidation and anti-apoptosis. However, the mechanisms remain unclear. Herein, we investigated whether DEX afforded lung protection by regulating the process of mitochondrial dynamics through the HIF-1a/HO-1 pathway in vivo and in vitro. Using C57BL/6J mice exposed to lipopolysaccharide, it was initially observed that preemptive administration of DEX (50μg/kg) alleviated lung pathologic injury, reduced oxidative stress indices (OSI), improved mitochondrial dysfunction, upregulated the expression of HIF-1α and HO-1, accompanied by shifting the dynamic course of mitochondria into fusion. Moreover, HO-1-knockout mice or HO-1 siRNA transfected NR8383 cells were pretreated with HIF-1α stabilizer DMOG and DEX to validate the effect of HIF-1a/HO-1 pathway on DEX-mediated mitochondrial dynamics in a model of endotoxin-induced lung injury. We found that pretreatment with DEX and DMOG distinctly relieved lung injury, decreased the levels of mitochondrial ROS and mtDNA, reduced OSI, increased nuclear accumulation of HIF-1a and HO-1 protein in wild type mice but not HO-1 KO mice. Similar observations were recapitulated in NC siRNA transfected NR8383 cells after LPS stimulation but not HO-1 siRNA transfected cells. Concertedly, DEX reversed the impaired mitochondrial morphology in LPS stimulated-wild type mice or NC siRNA transfected NR8383 cells, upregulated the expression of mitochondrial fusion protein, while downregulated the expression of fission protein in HIF-1a/HO-1 dependent pathway. Altogether, our data both in vivo and in vitro certified that DEX treatment ameliorated endotoxin-induced acute lung injury by preserving the dynamic equilibrium of mitochondrial fusion/fission through the regulation of HIF-1a/HO-1 signaling pathway.
53 citations
References
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TL;DR: Mutations in the newly identified gene appear to be responsible for the pathogenesis of Autosomal recessive juvenile parkinsonism, and the protein product is named ‘Parkin’.
Abstract: Parkinson's disease is a common neurodegenerative disease with complex clinical features1. Autosomal recessive juvenile parkinsonism (AR-JP)2,3 maps to the long arm of chromosome 6 (6q25.2-q27) and is linked strongly to the markers D6S305 and D6S253 (ref. 4); the former is deleted in one Japanese AR-JP patient5. By positional cloning within this microdeletion, we have now isolated a complementary DNA clone of 2,960 base pairs with a 1,395-base-pair open reading frame, encoding a protein of 465 amino acids with moderate similarity to ubiquitin at the amino terminus and a RING-finger motif at the carboxy terminus. The gene spans more than 500 kilobases and has 12 exons, five of which (exons 3–7) are deleted in the patient. Four other AR-JP patients from three unrelated families have a deletion affecting exon 4 alone. A 4.5-kilobase transcript that is expressed in many human tissues but is abundant in the brain, including the substantia nigra, is shorter in brain tissue from one of the groups of exon-4-deleted patients. Mutations in the newly identified gene appear to be responsible for the pathogenesis of AR-JP, and we have therefore named the protein product ‘Parkin’.
4,922 citations
TL;DR: This review describes the main mitochondrial sources of reactive species and the antioxidant defences that evolved to prevent oxidative damage in all the mitochondrial compartments and discusses various physiological and pathological scenarios resulting from an increased steady state concentration of mitochondrial oxidants.
Abstract: The reduction of oxygen to water proceeds via one electron at a time. In the mitochondrial respiratory chain, Complex IV (cytochrome oxidase) retains all partially reduced intermediates until full reduction is achieved. Other redox centres in the electron transport chain, however, may leak electrons to oxygen, partially reducing this molecule to superoxide anion (O2−•). Even though O2−• is not a strong oxidant, it is a precursor of most other reactive oxygen species, and it also becomes involved in the propagation of oxidative chain reactions. Despite the presence of various antioxidant defences, the mitochondrion appears to be the main intracellular source of these oxidants. This review describes the main mitochondrial sources of reactive species and the antioxidant defences that evolved to prevent oxidative damage in all the mitochondrial compartments. We also discuss various physiological and pathological scenarios resulting from an increased steady state concentration of mitochondrial oxidants.
4,282 citations
TL;DR: This review examines evolving concepts of sepsis and discusses new and potential therapies, including therapy with activated protein C, stringent control of blood glucose, and early goal-directed therapy to treat cellular oxygen deficit.
Abstract: Sepsis is the leading cause of death in critically ill patients in the United States. Yet the individual host response to septicemia is variable, depending on the patient's immune response, age, nutritional status, and coexisting conditions, as well as on the virulence of the organism and the size of the inoculum. This review examines evolving concepts of sepsis and discusses new and potential therapies. Recent clinical advances include therapy with activated protein C, stringent control of blood glucose, and early goal-directed therapy to treat cellular oxygen deficit. Future therapies may be focused on modulating the immune response in the light of the characteristics of the specific pathogen, the genetic profile of the patient, and the duration of the disease.
3,773 citations
TL;DR: The identification of two homozygous mutations affecting the PINK1 kinase domain in three consanguineous PARK6 families provide a direct molecular link between mitochondria and the pathogenesis of PD.
Abstract: Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of dopaminergic neurons in the substantia nigra We previously mapped a locus for a rare familial form of PD to chromosome 1p36 (PARK6) Here we show that mutations in PINK1 (PTEN-induced kinase 1) are associated with PARK6 We have identified two homozygous mutations affecting the PINK1 kinase domain in three consanguineous PARK6 families: a truncating nonsense mutation and a missense mutation at a highly conserved amino acid Cell culture studies suggest that PINK1 is mitochondrially located and may exert a protective effect on the cell that is abrogated by the mutations, resulting in increased susceptibility to cellular stress These data provide a direct molecular link between mitochondria and the pathogenesis of PD
3,224 citations
TL;DR: Current evidence that the pore complex is involved in outer-membrane rupture and release of these proteins during programmed cell death is reviewed, along with indications that transient pore opening may provoke 'accidental' apoptosis.
Abstract: This article reviews the involvement of the mitochondrial permeability transition pore in necrotic and apoptotic cell death. The pore is formed from a complex of the voltage-dependent anion channel (VDAC), the adenine nucleotide translocase and cyclophilin-D (CyP-D) at contact sites between the mitochondrial outer and inner membranes. In vitro, under pseudopathological conditions of oxidative stress, relatively high Ca2+ and low ATP, the complex flickers into an open-pore state allowing free diffusion of low-Mr solutes across the inner membrane. These conditions correspond to those that unfold during tissue ischaemia and reperfusion, suggesting that pore opening may be an important factor in the pathogenesis of necrotic cell death following ischaemia/reperfusion. Evidence that the pore does open during ischaemia/reperfusion is discussed. There are also strong indications that the VDAC-adenine nucleotide translocase-CyP-D complex can recruit a number of other proteins, including Bax, and that the complex is utilized in some capacity during apoptosis. The apoptotic pathway is amplified by the release of apoptogenic proteins from the mitochondrial intermembrane space, including cytochrome c, apoptosis-inducing factor and some procaspases. Current evidence that the pore complex is involved in outer-membrane rupture and release of these proteins during programmed cell death is reviewed, along with indications that transient pore opening may provoke 'accidental' apoptosis.
2,414 citations