Mitofusin 2 Promotes Apoptosis of CD4+ T Cells by Inhibiting Autophagy in Sepsis. Mediators Inflamm. 2017;2017:4926205. [PMID: 29358849 PMCID: PMC5735308 DOI: 10.1155/2017/4926205]

Luteolin induces ferroptosis in prostate cancer cells by promoting TFEB nuclear translocation and increasing ferritinophagy

BACKGROUND

As the second most common cancer in men and the leading cause of cancer-related death, prostate cancer (PCa) could potentially be treated by inducing ferroptosis. In this study, we aimed to investigate whether luteolin could induce ferroptosis in PCa cells through the transcription Factor EB (TFEB).

METHODS

Different concentrations of luteolin were applied to treat normal prostate epithelial cells RWPE-1 and PCa cell lines DU145, PC-3, VCaP, and LNcaP. Ferrostatin-1 (Fer-1), Necrostain-1 (Nec-1), 3-methyladenine (3-MA), chloroquine (CQ), and the apoptosis inhibitor benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (Z-VAD-FMK) were added to treat DU145 and PC-3 cells. Additionally, we knocked down TFEB and performed in vitro cell experiments. Finally, tumor-forming experiments in nude mice were conducted to verify luteolin mechanism in PCa after knocking down TFEB.

RESULTS

There was no significant difference in RWPE-1 at 12, 24, and 48 h after treatment with 60 μM luteolin. However, a significant difference was observed between DU145 and PC-3 cells. Luteolin exhibited a promoting effect on PCa cell death. After treatment with luteolin, cell viability, and Ki67 expression were decreased, and AnV-PI-positive dead cells were increased. Fer-1, Nec-1, 3-MA, and Z-VAD-FMK reversed luteolin effects on DU145 and PC-3 cell viability, proliferation, and AnV-PI-positive dead cells. Among them, Fer-1 and 3-MA were more effective. Luteolin-induced increased autophagy and ferroptosis in DU145 and PC-3 cells. Moreover, luteolin promoted ferroptosis by inducing increased autophagy in DU145 and PC-3 cells. However, knockdown of TFEB reversed the ability of luteolin to induce lysosome degradation of ferritin. In addition, luteolin promoted PCa ferroptosis by inducing ferritinophagy in vivo.

CONCLUSIONS

Luteolin-induced ferroptosis in PCa cells by promoting TFEB nuclear translocation and increasing ferritinophagy.

In an experimental myocardial infarction model, L-arginine pre-intervention may exert cardioprotective effects by regulating OTULIN levels and mitochondrial dynamics

The experimental myocardial infarction (MI) model originating from isoproterenol (ISO) is frequently preferred in research due to its similarity to MI-induced damage in humans. Beneficial effects of L-arginine (L-Arg), a semi-essential amino acid, in cardiovascular diseases have been shown in many studies. This study was carried out to determine whether L-Arg pre-intervention has protective effects on heart tissue in the experimental MI model. The 28 rats used in the study were randomly divided into 4 equal groups: control, L-Arg, ISO, and L-Arg+ISO. Upon completion of all applications, cardiac markers in serum and biochemical, histopathological, and immunohistochemical examinations in cardiac tissues were performed. Cardiac markers, histopathological changes, oxidative stress, inflammation, and apoptosis were increased in the experimental MI model. In addition, administration of ISO deregulated OTULIN levels and mitochondrial dynamics in heart tissue. However, L-Arg pre-intervention showed a significant protective effect against changes in ISO-induced MI. L-Arg supplementation with cardioprotective effect may reduce the risks of possible pathophysiological processes in MI.

The effect of sitagliptin combined with rosiglitazone on autophagy and inflammation in polycystic ovary syndrome by regulating PI3K/AKT/mTOR and TLR4/NF-κB pathway

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder. Sitagliptin (Sit) and rosiglitazone (Ros) are widely used to treat PCOS, but the mechanism is unclear. This study explored the mechanism that Sit and Ros inhibited autophagy and inflammation in PCOS. In this study, 50 female SD rats were divided into 5 groups (n = 10): control, PCOS, Sit, Ros, and Sit+Ros group. The body weight and ovarian weight were measured 2 h after the last administration, and fasting blood glucose, insulin levels were determined. Lipid metabolism and pathological changes were detected by an automatic biochemical analyzer and HE staining. Sex hormone, oxidative stress and inflammatory levels were detected by ELISA. PCR detected IL-18, TNF-α, IL-6, IL-1β, ATG3, and ATG12 mRNA. The PI3K/AKT/mTOR, TLR4/NF-κB pathway and autophagy-related proteins were detected by western blot. Finally, the number of autophagolysosomes was detected by transmission electron microscopy. Sit or Ros alone reduced body weight, ovarian weight, fasting blood glucose, and insulin levels in PCOS rats. It also improved lipid metabolism, sex hormone levels, oxidative stress and pathological changes, restored the estrous cycle, and corpus luteum quantity. In addition, it could reduce the levels of IL-18, TNF-α, IL-6, IL-1β, ATG3, and ATG12 mRNA, inhibit the expression of Beclin1, LC3, PI3K/AKT/mTOR, and TLR4/NF-κB pathway proteins. The Sit+Ros group was more effective than single administration. In conclusion, Sit+Ros inhibited the PI3K/AKT/mTOR, TLR4/NF-κB pathways, thereby inhibiting the autophagy and inflammation of PCOS rats, which will provide a theoretical basis for PCOS.

USP9x promotes CD8 + T-cell dysfunction in association with autophagy inhibition in septic liver injury

Sepsis is a life-threatening condition manifested by concurrent inflammation and immunosuppression. Ubiquitin-specific peptidase 9, X-linked (USP9x), is a USP domain-containing deubiquitinase which is required in T-cell development. In the present study, we investigate whether USP9x plays a role in hepatic CD8 ⁺ T-cell dysfunction in septic mice. We find that CD8 ⁺ T cells are decreased in the blood of septic patients with liver injury compared with those without liver injury, the CD4/CD8 ratio is increased, and the levels of cytolytic factors, granzyme B and perforin are downregulated. The number of hepatic CD8 ⁺ T cells and USP9x expression are both increased 24 h after cecal ligation and puncture-induced sepsis in a mouse model, a pattern similar to liver injury. The mechanism involves promotion of CD8 ⁺ T-cell dysfunction by USP9x associated with suppression of cell cytolytic activity via autophagy inhibition, which is reversed by the USP9x inhibitor WP1130. In the in vivo studies, autophagy is significantly increased in hepatic CD8 ⁺ T cells of septic mice with conditional knockout of mammalian target of rapamycin. This study shows that USP9x has the potential to be used as a therapeutic target in septic liver injury.

The Interplay between Host Defense, Infection, and Clinical Status in Septic Patients: A Narrative Review

Sepsis is a life-threatening condition that arises when the body's response to an infection injures its own tissues and organs. Despite significant morbidity and mortality throughout the world, its pathogenesis and mechanisms are not clearly understood. In this narrative review, we aimed to summarize the recent developments in our understanding of the hallmarks of sepsis pathogenesis (immune and adaptive immune response, the complement system, the endothelial disfunction, and autophagy) and highlight novel laboratory diagnostic approaches. Clinical management is also discussed with pivotal consideration for antimicrobic therapy management in particular settings, such as intensive care unit, altered renal function, obesity, and burn patients.

The role of mitophagy in pulmonary sepsis

Sepsis is a systemic inflammatory disease with an unacceptably high mortality rate caused by an infection or trauma that involves both innate and adaptive immune systems. Inflammatory events activate different downstream pathways leading to tissue damage and ultimately multi-organ failure. Mitochondria are responsible for cellular energy, thermoregulation, metabolite biosynthesis, intracellular calcium regulation, and cell death. Damaged mitochondria induce the high Ca²⁺ influx through mitochondrial calcium uniporter (MCU). It also generates excessive Reactive oxygen species (ROS) and releases mtDNA into the cytoplasm, which causes induction of NLRP3 inflammasome and apoptosis. Mitophagy (Autophagy of damaged mitochondria) controls mitochondrial dynamics and function. It also maintains cellular homeostasis. This review is about how pulmonary sepsis affects the body. What is the aftermath of sepsis, and how mitophagy affects Acute Lung Injury and macrophage polarisation to overcome the damages.

miR-20b suppresses mitochondrial dysfunction-mediated apoptosis to alleviate hyperoxia-induced acute lung injury by directly targeting MFN1 and MFN2

Supplemental oxygen is commonly used to treat severe respiratory failure, while prolonged exposure to hyperoxia can induce acute lung injury characterized by the accumulation of reactive oxygen species (ROS) and pulmonary inflammation. Dysregulation of microRNAs contributes to multiple diseases, including hyperoxia-induced acute lung injury (HALI). In this study, we explored the roles of miR-20b in mediating the response of type II alveolar epithelial cells (ACE IIs) to hyperoxia and the potential underlying mechanisms. We found that miR-20b was significantly decreased in the lung tissues of HALI models and H2O2-treated ACE IIs. Hyperoxia induced the release of TNF-α, decreased the mitochondrial membrane potential, and led to excessive ROS production and cell apoptosis. Overexpression of miR-20b suppressed the hyperoxia-induced biological effects in ACE IIs. miR-20b negatively regulated the expression levels of Mitofusin 1 (MFN1) and MFN2, the two key proteins of mitochondrial fusion, via complementarily binding to the 3'-untranslated regions of mRNAs. Furthermore, both in vivo and in vitro, upregulation of MFN1 and MFN2 aggravated lung damage and cell apoptosis that were alleviated by miR-20b overexpression. These results provided new insights into the involvement of the miR-20b/MFN1/2 signaling pathway in HALI.

Autophagy in liver diseases

Autophagy is the liver cell energy recycling system regulating a variety of homeostatic mechanisms. Damaged organelles, lipids and proteins are degraded in the lysosomes and their elements are re-used by the cell. Investigations on autophagy have led to the award of two Nobel Prizes and a health of important reports. In this review we describe the fundamental functions of autophagy in the liver including new data on the regulation of autophagy. Moreover we emphasize the fact that autophagy acts like a two edge sword in many occasions with the most prominent paradigm being its involvement in the initiation and progress of hepatocellular carcinoma. We also focused to the implication of autophagy and its specialized forms of lipophagy and mitophagy in the pathogenesis of various liver diseases. We analyzed autophagy not only in well studied diseases, like alcoholic and nonalcoholic fatty liver and liver fibrosis but also in viral hepatitis, biliary diseases, autoimmune hepatitis and rare diseases including inherited metabolic diseases and also acetaminophene hepatotoxicity. We also stressed the different consequences that activation or impairment of autophagy may have in hepatocytes as opposed to Kupffer cells, sinusoidal endothelial cells or hepatic stellate cells. Finally, we analyzed the limited clinical data compared to the extensive experimental evidence and the possible future therapeutic interventions based on autophagy manipulation.

CD8+ T cell survival in lethal fungal sepsis was ameliorated by T-cell-specific mTOR deletion

Lethal fungal sepsis causes high morbidity and mortality in intensive care patients. Fungal infections have an immunological basis, and it has been shown in recent studies that decreased CD8⁺ T-cell count in fungal infections is related to prognosis, while the underlying mechanism is still unclear. Here, a lethal fungal sepsis model induced by candidemia was created and we found a decreased CD8⁺ T-cell count and exaggerated apoptosis. Simultaneously, expression of light chain (LC)3B in CD8⁺ T cells increased, along with increased autophagosomes and accumulation of p62 in infected mice. We regulated the activity of the mammalian target of rapamycin (mTOR) pathway using T-cell-specific mTOR/ TSC1 deletion mice. We observed increased number of autophagosomes and expression of LC3B in CD8⁺T cells after T-cell-specific mTOR knockout, while accumulation of p62 was not ameliorated, and there was no increase in the number of autolysosomes. Apoptosis rate and expression of BIM, a pro-apoptotic gene, decreased in CD8⁺ T cells in mTOR-deletion mice but increased in TSC1-deletion mice. Our results showed increased CD8⁺ T-cell death in spleen of lethal fungal sepsis mice, and decreased expression of mTOR ameliorated CD8⁺ T-cell survival. mTOR may be a possible target to reverse CD8⁺ T-cell immune dysfunction in lethal fungal sepsis.

Role of Mitofusins and Mitophagy in Life or Death Decisions

Mitochondria entail an incredible dynamism in their morphology, impacting death signaling and selective elimination of the damaged organelles. In turn, by recycling the superfluous or malfunctioning mitochondria, mostly prevalent during aging, mitophagy contributes to maintain a healthy mitochondrial network. Mitofusins locate at the outer mitochondrial membrane and control the plastic behavior of mitochondria, by mediating fusion events. Besides deciding on mitochondrial interconnectivity, mitofusin 2 regulates physical contacts between mitochondria and the endoplasmic reticulum, but also serves as a decisive docking platform for mitophagy and apoptosis effectors. Thus, mitofusins integrate multiple bidirectional inputs from and into mitochondria and ensure proper energetic and metabolic cellular performance. Here, we review the role of mitofusins and mitophagy at the cross-road between life and apoptotic death decisions. Furthermore, we highlight the impact of this interplay on disease, focusing on how mitofusin 2 and mitophagy affect non-alcoholic fatty liver disease.

Role of Autophagy in Lung Inflammation

Autophagy is a cellular recycling system found in almost all types of eukaryotic organisms. The system is made up of a variety of proteins which function to deliver intracellular cargo to lysosomes for formation of autophagosomes in which the contents are degraded. The maintenance of cellular homeostasis is key in the survival and function of a variety of human cell populations. The interconnection between metabolism and autophagy is extensive, therefore it has a role in a variety of different cell functions. The disruption or dysfunction of autophagy in these cell types have been implicated in the development of a variety of inflammatory diseases including asthma. The role of autophagy in non-immune and immune cells both lead to the pathogenesis of lung inflammation. Autophagy in pulmonary non-immune cells leads to tissue remodeling which can develop into chronic asthma cases with long term effects. The role autophagy in the lymphoid and myeloid lineages in the pathology of asthma differ in their functions. Impaired autophagy in lymphoid populations have been shown, in general, to decrease inflammation in both asthma and inflammatory disease models. Many lymphoid cells rely on autophagy for effector function and maintained inflammation. In stark contrast, autophagy deficient antigen presenting cells have been shown to have an activated inflammasome. This is largely characterized by a T_H17 response that is accompanied with a much worse prognosis including granulocyte mediated inflammation and steroid resistance. The cell specificity associated with changes in autophagic flux complicates its targeting for amelioration of asthmatic symptoms. Differing asthmatic phenotypes between T_H2 and T_H17 mediated disease may require different autophagic modulations. Therefore, treatments call for a more cell specific and personalized approach when looking at chronic asthma cases. Viral-induced lung inflammation, such as that caused by SARS-CoV-2, also may involve autophagic modulation leading to inflammation mediated by lung resident cells. In this review, we will be discussing the role of autophagy in non-immune cells, myeloid cells, and lymphoid cells for their implications into lung inflammation and asthma. Finally, we will discuss autophagy's role viral pathogenesis, immunometabolism, and asthma with insights into autophagic modulators for amelioration of lung inflammation.

A novel mechanism of intervertebral disc degeneration: imbalance between autophagy and apoptosis

Aim: To identify a key competitive endogenous RNA network for intervertebral disc degeneration. Materials & methods: Based on circular RNA, microRNA and mRNA expression profiles of nucleus pulposus cells, a variety of bioinformatics methods were used to screen key molecular structures and construct competitive endogenous RNA networks. Results: 190 upregulated genes and 77 downregulated genes were identified. Gene ontology/Kyoto Encyclopedia of Genes and Genomes functional analysis showed that autophagy was out of balance with apoptosis. Nine hub genes, five hub microRNAs and eight hub circular RNAs were obtained through progressive reverse prediction and verification. Conclusion: We believe that disc degeneration is caused by an imbalance between autophagy and apoptosis in nucleus pulposus cells, which may provide nonsurgical treatment for the future delay or prevention of spinal degenerative diseases associated with intervertebral disc degeneration.

T-cell-specific mTOR deletion in mice ameliorated CD4+ T-cell survival in lethal sepsis induced by severe invasive candidiasis

The mammalian target of rapamycin (mTOR) pathway can mediate T-cell survival; however, the role of this pathway in T-cell survival during fungal sepsis is unclear. Here, we investigated the role of the mTOR pathway in CD4+ T-cell survival in a mouse model of rapidly progressive lethal sepsis induced by severe invasive candidiasis and explored the possible mechanism. The decrease in CD4+ T-cell survival following fungal sepsis was ameliorated in mice with a T-cell-specific mTOR deletion, whereas it was exacerbated in mice with a T-cell-specific tuberous sclerosis complex (TSC)1 deletion. To explore the mechanism further, we measured expression of autophagy proteins light chain 3B and p62/sequestosome 1 in CD4+ T cells. Both proteins were increased in T-cell-specific mTOR knockout mice but lower in T-cell-specific TSC1 knockout mice. Transmission electron microscopy revealed that T-cell-specific mTOR knockout mice had more autophagosomes than wild-type mice following fungal sepsis. CD4+ T-cell mTOR knockout decreased CD4+ T-cell apoptosis in fungal sepsis. Most notably, the T-cell-specific mTOR deletion mice had an increased survival rate after fungal sepsis. These results suggest that the mTOR pathway plays a vital role in CD4+ T-cell survival during fungal sepsis, partly through the autophagy-apoptosis pathway.

Sepsis roadmap: What we know, what we learned, and where we are going

Sepsis is a life-threatening condition originating as a result of systemic blood infection causing, one or more organ damage due to the dysregulation of the immune response. In 2017, the world health organization (WHO) declared sepsis as a disease of global health priority, needing special attention due to its high prevalence and mortality around the world. Most of the therapeutics targeting sepsis have failed in the clinics. The present review highlights the history of the sepsis, its immunopathogenesis, and lessons learned after the failure of previously used immune-based therapies. The subsequent section, where to go describes in details the importance of the complement system (CS), autophagy, inflammasomes, and microbiota along with their targeting to manage sepsis. These systems are interconnected to each other, thus targeting one may affect the other. We are in an urgent need for a multi-targeting therapeutic approach for sepsis.

Sinomenine ameliorates intervertebral disc degeneration via inhibition of apoptosis and autophagy in vitro and in vivo

BACKGROUND

Aberrant apoptosis in nucleus pulposus (NP) cells is the primary cause of intervertebral disc degeneration (IDD). In contrast, a large number of studies have confirmed that autophagy may protect NP cells from apoptosis. Sinomenine is an alkaloid monomer, which has been reported to stimulate cell autophagy. Therefore, the aim of the present study was to investigate the effects of sinomenine on IDD.

METHODS

The effects of sinomenine on the proliferation and apoptosis of NP cells were evaluated with the CCK-8 assay and Annexin V/PI staining, respectively.

RESULTS

The data obtained from the present study demonstrated that sinomenine could notably reverse TBHP-induced growth inhibition and apoptosis in rat NP cells. In addition, sinomenine significantly induced autophagy in rat NP cells, which was completely inhibited by 3-methyladenine (3MA). In addition, the protective effect of sinomenine against TBHP in rat NP cells was abolished following treatment with 3MA. Finally, an in vivo study further confirmed that sinomenine could ameliorate rat IDD.

CONCLUSION

Taken together, the results of the present study indicated sinomenine could ameliorate rat IDD via induction of autophagy in vitro and in vivo. These findings suggest the therapeutic potential of sinomenine in the prevention of IDD.

The Role of Autophagy in Sepsis: Protection and Injury to Organs

Sepsis is a systemic inflammatory disease with infection, and autophagy has been shown to play an important role in sepsis. This review summarizes the main regulatory mechanisms of autophagy in sepsis and its latest research. Recent studies have shown that autophagy can regulate innate immune processes and acquired immune processes, and the regulation of autophagy in different immune cells is different. Mitophagy can select damaged mitochondria and remove it to deal with oxidative stress damage. The process of mitophagy is regulated by other factors. Non-coding RNA is also an important factor in the regulation of autophagy. In addition, more and more studies in recent years have shown that autophagy plays different roles in different organs. It tends to be protective in the lungs, heart, kidneys, and brain, and tends to be damaging in skeletal muscle. We also mentioned that some drugs can regulate autophagy. The process of modulating autophagy through drug intervention appears to be a new potential hope for the treatment of sepsis.

Mitofusins: Disease Gatekeepers and Hubs in Mitochondrial Quality Control by E3 Ligases

Mitochondria are dynamic organelles engaged in quality control and aging processes. They constantly undergo fusion, fission, transport, and anchoring events, which empower mitochondria with a very interactive behavior. The membrane remodeling processes needed for fusion require conserved proteins named mitofusins, MFN1 and MFN2 in mammals and Fzo1 in yeast. They are the first determinants deciding on whether communication and content exchange between different mitochondrial populations should occur. Importantly, each cell possesses hundreds of mitochondria, with a different severity of mitochondrial mutations or dysfunctional proteins, which potentially spread damage to the entire network. Therefore, the degree of their merging capacity critically influences cellular fitness. In turn, the mitochondrial network rapidly and dramatically changes in response to metabolic and environmental cues. Notably, cancer or obesity conditions, and stress experienced by neurons and cardiomyocytes, for example, triggers the downregulation of mitofusins and thus fragmentation of mitochondria. This places mitofusins upfront in sensing and transmitting stress. In fact, mitofusins are almost entirely exposed to the cytoplasm, a topology suitable for a critical relay point in information exchange between mitochondria and their cellular environment. Consistent with their topology, mitofusins are either activated or repressed by cytosolic post-translational modifiers, mainly by ubiquitin. Ubiquitin is a ubiquitous small protein orchestrating multiple quality control pathways, which is covalently attached to lysine residues in its substrates, or in ubiquitin itself. Importantly, from a chain of events also mediated by E1 and E2 enzymes, E3 ligases perform the ultimate and determinant step in substrate choice. Here, we review the ubiquitin E3 ligases that modify mitofusins. Two mitochondrial E3 enzymes—March5 and MUL1—one ligase located to the ER—Gp78—and finally three cytosolic enzymes—MGRN1, HUWE1, and Parkin—were shown to ubiquitylate mitofusins, in response to a variety of cellular inputs. The respective outcomes on mitochondrial morphology, on contact sites to the endoplasmic reticulum and on destructive processes, like mitophagy or apoptosis, are presented. Ultimately, understanding the mechanisms by which E3 ligases and mitofusins sense and bi-directionally signal mitochondria-cytosolic dysfunctions could pave the way for therapeutic approaches in neurodegenerative, cardiovascular, and obesity-linked diseases.

The protective role of autophagy in sepsis

Sepsis is characterized by life-threatening organ dysfunction caused by a deregulated host response to infection. Autophagy is one of the innate immune defense mechanisms against microbial attack. Previous studies have demonstrated that autophagy is activated initially in sepsis, followed by a subsequent phase of impairment. A number of sepsis-related studies have shown that autophagy plays a protective role in multiple organ injuries partly by clearing pathogens, regulating inflammation and metabolism, inhibiting apoptosis and suppressing immune reactions. In this review, we present a general overview of and recent advances in the role of autophagy in sepsis and consider the therapeutic potential of autophagy activators in treating sepsis.