Heat shock increases levels of reactive oxygen species, autophagy and apoptosis

Mild heat shock at 40 °C increases levels of autophagy: Role of Nrf2

The exposure to low doses of stress induces an adaptive survival response that involves the upregulation of cellular defense systems such as heat shock proteins (Hsps), anti-apoptosis proteins, and antioxidants. Exposure of cells to elevated, non-lethal temperatures (39-41 °C) is an adaptive survival response known as thermotolerance, which protects cells against subsequent lethal stress such as heat shock (>41.5 °C). However, the initiating factors in this adaptive survival response are not understood. This study aims to determine whether autophagy can be activated by heat shock at 40 °C and if this response is mediated by the transcription factor Nrf2. Thermotolerant cells, which were developed during 3 h at 40 °C, were resistant to caspase activation at 42 °C. Autophagy was activated when cells were heated from 5 to 60 min at 40 °C. Levels of acidic vesicular organelles (AVOs) and autophagy proteins Beclin-1, LC3-II/LC3-I, Atg7, Atg5, Atg12-Atg5, and p62 were increased. When Nrf2 was overexpressed or depleted in cells, levels of AVOs and autophagy proteins were higher in unstressed cells, compared to the wild type. Stress induced by mild heat shock at 40 °C further increased levels of most autophagy proteins in cells with overexpression or depletion of Nrf2. Colocalization of p62 and Keap1 occurred. When Nrf2 levels are low, activation of autophagy would likely compensate as a defense mechanism to protect cells against stress. An improved understanding of autophagy in the context of cellular responses to physiological heat shock could be useful for cancer treatment by hyperthermia and the protective role of adaptive responses against environmental stresses.

Calycosin Enhances Heat Shock Related-Proteins in H9c2 Cells to Modulate Survival and Apoptosis against Heat Shock

Heat shock proteins (HSPs), which function as chaperones, are activated in response to various environmental stressors. In addition to their role in diverse aspects of protein production, HSPs protect against harmful protein-related stressors. Calycosin exhibits numerous beneficial properties. This study aims to explore the protective effects of calycosin in the heart under heat shock and determine its underlying mechanism. H9c2 cells, western blot, TUNEL staining, flow cytometry, and immunofluorescence staining were used. The time-dependent effects of heat shock analyzed using western blot revealed increased HSP expression for up to 2[Formula: see text]h, followed by protein degradation after 4[Formula: see text]h. Hence, a heat shock damage duration of 4[Formula: see text]h was chosen for subsequent investigations. Calycosin administered post-heat shock demonstrated dose-dependent recovery of cell viability. Under heat shock conditions, calycosin prevented the apoptosis of H9c2 cells by upregulating HSPs, suppressing p-JNK, enhancing Bcl-2 activation, and inhibiting cleaved caspase 3. Calycosin also inhibited Fas/FasL expression and activated cell survival markers (p-PI3K, p-ERK, p-Akt), indicating their cytoprotective properties through PI3K/Akt activation and JNK inhibition. TUNEL staining and flow cytometry confirmed that calycosin reduced apoptosis. Moreover, calycosin reversed the inhibitory effects of quercetin on HSF1 and Hsp70 expression, illustrating its role in enhancing Hsp70 expression through HSF1 activation during heat shock. Immunofluorescence staining demonstrated HSF1 translocation to the nucleus following calycosin treatment, emphasizing its cytoprotective effects. In conclusion, calycosin exhibits pronounced protective effects against heat shock-induced damages by modulating HSP expression and regulating key signaling pathways to promote cell survival in H9c2 cells.

Research progress on the role of autophagy in the development of varicocele

Varicocele (VC) is a common cause of infertility in men. Pathophysiological changes caused by VC, such as testicular hypoxia, high temperatures, oxidative stress, abnormal reproductive hormones, and Cd accumulation, can induce autophagy, thus affecting the reproductive function in patients with this condition. Autophagy regulators can be classified as activators or inhibitors. Autophagy activators upregulate autophagy, reduce the damage to the testis and epididymis, inhibit spermatogenic cell apoptosis, and protect fertility. In contrast, autophagy inhibitors block autophagy and aggravate the damage to the reproductive functions. Therefore, elucidating the role of autophagy in the occurrence, development, and regulation of VC may provide additional therapeutic options for men with infertility and VC. In this review, we briefly describe the progress made in autophagy research in the context of VC.

Ethanolic extract from leaves of tithonia diversifolia induces apoptosis in HCT-116 cells through oxidative stress

Tithonia diversifolia is a perennial bushy plant found in South America with significant ethnopharmacological importance as an antimalarial, antidiabetic, antibacterial, and anticancer agent. The aim of the present study was to determine the cytotoxicity of the ethanolic extract from leaves of T. diversifolia (TdE) on human cancer cell lines (HCT-116, SNB-19, NCIH-460 and MCF-7), as well as the mechanism of action involved in cell death and cellular modulation of oxidative stress. The TdE exhibited significant activity with IC50 values ranging from 7.12 to 38.41 μg/ml, with HCT-116 being the most sensitive cell line. Subsequent experiments were conducted with HCT-116 cell line. TdE decreased the number of viable cells, followed by induction of apoptotic events, increase in mitochondrial membrane permeabilization, and enhanced G2/M phase of the cell cycle. Pro-oxidative effects including elevated acidic vesicular organelle formation, lipid peroxidation, and nitric oxide by-products, as well as reduced levels of intracellular glutathione and reactive oxygen species production were also observed following incubation with TdE, which may lead to DNA damage followed by apoptotic cell death. These results demonstrate the potential of TdE ethanolic leaf extraction for biological activity and enhance the importance of continuing to study natural sources of plants for the development of anticancer agents.

The redox-responsive roles of intermediate filaments in cellular stress detection, integration and mitigation

Intermediate filaments are critical for cell and tissue homeostasis and for stress responses. Cytoplasmic intermediate filaments form versatile and dynamic assemblies that interconnect cellular organelles, participate in signaling and protect cells and tissues against stress. Here we have focused on their involvement in redox signaling and oxidative stress, which arises in numerous pathophysiological situations. We pay special attention to type III intermediate filaments, mainly vimentin, because it provides a physical interface for redox signaling, stress responses and mechanosensing. Vimentin possesses a single cysteine residue that is a target for multiple oxidants and electrophiles. This conserved residue fine tunes vimentin assembly, response to oxidative stress and crosstalk with other cellular structures. Here we integrate evidence from the intermediate filament and redox biology fields to propose intermediate filaments as redox sentinel networks of the cell. To support this, we appraise how vimentin detects and orchestrates cellular responses to oxidative and electrophilic stress.

The Snf5-Hsf1 transcription module synergistically regulates stress responses and pathogenicity by maintaining ROS homeostasis in Sclerotinia sclerotiorum

The SWI/SNF complex is guided to the promoters of designated genes by its co-operator to activate transcription in a timely and appropriate manner to govern development, pathogenesis, and stress responses in fungi. Nevertheless, knowledge of the complexes and their co-operator in phytopathogenic fungi is still fragmented. We demonstrate that the heat shock transcription factor SsHsf1 guides the SWI/SNF complex to promoters of heat shock protein (hsp) genes and antioxidant enzyme genes using biochemistry and pharmacology. This is accomplished through direct interaction with the complex subunit SsSnf5 under heat shock and oxidative stress. This results in the activation of their transcription and mediates histone displacement to maintain reactive oxygen species (ROS) homeostasis. Genetic results demonstrate that the transcription module formed by SsSnf5 and SsHsf1 is responsible for regulating morphogenesis, stress tolerance, and pathogenicity in Sclerotinia sclerotiorum, especially by directly activating the transcription of hsp genes and antioxidant enzyme genes counteracting plant-derived ROS. Furthermore, we show that stress-induced phosphorylation of SsSnf5 is necessary for the formation of the transcription module. This study establishes that the SWI/SNF complex and its co-operator cooperatively regulate the transcription of hsp genes and antioxidant enzyme genes to respond to host and environmental stress in the devastating phytopathogenic fungi.

Harnessing Hyperthermia: Molecular, Cellular, and Immunological Insights for Enhanced Anticancer Therapies

Hyperthermia, the raising of tumor temperature (≥39°C), holds great promise as an adjuvant treatment for cancer therapy. This review focuses on 2 key aspects of hyperthermia: its molecular and cellular effects and its impact on the immune system. Hyperthermia has profound effects on critical biological processes. Increased temperatures inhibit DNA repair enzymes, making cancer cells more sensitive to chemotherapy and radiation. Elevated temperatures also induce cell cycle arrest and trigger apoptotic pathways. Furthermore, hyperthermia modifies the expression of heat shock proteins, which play vital roles in cancer therapy, including enhancing immune responses. Hyperthermic treatments also have a significant impact on the body's immune response against tumors, potentially improving the efficacy of immune checkpoint inhibitors. Mild systemic hyperthermia (39°C-41°C) mimics fever, activating immune cells and raising metabolic rates. Intense heat above 50°C can release tumor antigens, enhancing immune reactions. Using photothermal nanoparticles for targeted heating and drug delivery can also modulate the immune response. Hyperthermia emerges as a cost-effective and well-tolerated adjuvant therapy when integrated with immunotherapy. This comprehensive review serves as a valuable resource for the selection of patient-specific treatments and the guidance of future experimental studies.

Research progress of hyperthermia in tumor therapy by influencing metabolic reprogramming of tumor cells

Cellular metabolic reprogramming is an important feature of malignant tumors. Metabolic reprogramming causes changes in the levels or types of specific metabolites inside and outside the cell, which affects tumorigenesis and progression by influencing gene expression, the cellular state, and the tumor microenvironment. During tumorigenesis, a series of changes in the glucose metabolism, fatty acid metabolism, amino acid metabolism, and cholesterol metabolism of tumor cells occur, which are involved in the process of cellular carcinogenesis and constitute part of the underlying mechanisms of tumor formation. Hyperthermia, as one of the main therapeutic tools for malignant tumors, has obvious effects on tumor cell metabolism. In this paper, we will combine the latest research progress in the field of cellular metabolic reprogramming and focus on the current experimental research and clinical treatment of hyperthermia in cellular metabolic reprogramming to discuss the feasibility of cellular metabolic reprogramming-related mechanisms guiding hyperthermia in malignant tumor treatment, so as to provide more ideas for hyperthermia to treat malignant tumors through the direction of cellular metabolic reprogramming.

Roles of Stress Response in Autophagy Processes and Aging-Related Diseases

The heat shock factor 1 (HSF1)-mediated stress response pathway and autophagy processes play important roles in the maintenance of proteostasis. Autophagy processes are subdivided into three subtypes: macroautophagy, chaperone-mediated autophagy (CMA), and microautophagy. Recently, molecular chaperones and co-factors were shown to be involved in the selective degradation of substrates by these three autophagy processes. This evidence suggests that autophagy processes are regulated in a coordinated manner by the HSF1-mediated stress response pathway. Recently, various studies have demonstrated that proteostasis pathways including HSF1 and autophagy are implicated in longevity. Furthermore, they serve as therapeutic targets for aging-related diseases such as cancer and neurodegenerative diseases. In the future, these studies will underpin the development of therapies against various diseases.

A Preliminary Study of Mild Heat Stress on Inflammasome Activation in Murine Macrophages

Inflammation and mitochondrial-dependent oxidative stress are interrelated processes implicated in multiple neuroinflammatory disorders, including Alzheimer's disease (AD) and depression. Exposure to elevated temperature (hyperthermia) is proposed as a non-pharmacological, anti-inflammatory treatment for these disorders; however, the underlying mechanisms are not fully understood. Here we asked if the inflammasome, a protein complex essential for orchestrating the inflammatory response and linked to mitochondrial stress, might be modulated by elevated temperatures. To test this, in preliminary studies, immortalized bone-marrow-derived murine macrophages (iBMM) were primed with inflammatory stimuli, exposed to a range of temperatures (37-41.5 °C), and examined for markers of inflammasome and mitochondrial activity. We found that exposure to mild heat stress (39 °C for 15 min) rapidly inhibited iBMM inflammasome activity. Furthermore, heat exposure led to decreased ASC speck formation and increased numbers of polarized mitochondria. These results suggest that mild hyperthermia inhibits inflammasome activity in the iBMM, limiting potentially harmful inflammation and mitigating mitochondrial stress. Our findings suggest an additional potential mechanism by which hyperthermia may exert its beneficial effects on inflammatory diseases.

Heat Stress-Induced Intestinal Barrier Impairment: Current Insights into the Aspects of Oxidative Stress and Endoplasmic Reticulum Stress

Heat stress (HS) occurs when the sensible temperature of animals exceeds their thermoregulatory capacity, a condition that exerts a detrimental impact on health and growth. The intestinal tract, as a highly sensitive organ, has been shown to respond to HS by exhibiting mucosal injury, intestinal leakage, and disturbances in the gut microbiota. Oxidative stress and endoplasmic reticulum stress (ERS) are both potential outcomes of long-term exposure to high temperatures and have been linked to apoptosis, autophagy, and ferroptosis. In addition, HS alters the composition of the gut microbiota accompanied by changed levels of bacterial components and metabolites, rendering the gut more vulnerable to stress-related injury. In this review, we present recent advances in mechanisms of oxidative stress-associated ERS in response to HS, which is destructive to intestinal barrier integrity. The involvement of autophagy and ferroptosis in ERS was highlighted. Further, we summarize the relevant findings regarding the engagement of gut microbiota-derived components and metabolites in modulation of intestinal mucosal injury induced by HS.

Programmed Upregulation of HSP70 by Metal-Organic Frameworks Nanoamplifier for Enhanced Microwave Thermal-Immunotherapy

Thermotherapy can directly kill tumor cells whilst being accompanied by immune-enhancing effects. However, this immune-enhancing effect suffers from insufficient expression of immune response factors (e.g., heat shock protein 70, HSP70), resulting in no patient benefiting due to the recurrence of tumor cells after thermotherapy. Herein, a nanoengineered strategy of programmed upregulating of the immune response factors for amplifying synergistic therapy is explored. Metal-organic frameworks nanoamplifiers (teprenone/nitrocysteine@ZrMOF-NH₂ @L-menthol@triphenylphosphine, GGA/CSNO@ZrMOF-NH₂ -LM-TPP nanoamplifier, and GCZMT nanoamplifier) achieve excellent microwave (MW) thermal-immunotherapy by programmed induction of HSP70 expression. After intravenous administration, GCZMT nanoamplifiers target the mitochondria, and then release nitric oxide (NO) under MW irradiation. NO inhibits the growth of tumor cells by interfering with the energy supply of cells. Subsequently, under the combination of MW, NO, and GGA, HSP70 expression can be programmed upregulated, which can induce the response of cytotoxic CD4⁺ T cells and CD8⁺ T cells, and effectively activate antitumor immunotherapy. Hence, GCZMT nanoamplifier-mediated MW therapy can achieve a satisfactory therapeutic effect with the tumor inhibition of 97%. This research offers a distinctive insight into the exploitation of metal-organic frameworks nanoamplifiers for enhanced tumor therapy, which provides a new approach for highly effective cancer treatment.

The role of calcium-calpain pathway in hyperthermia

Hyperthermia is a promising anticancer treatment modality. Heat stress stimulates proteolytic machineries to regulate cellular homeostasis. Calpain, an intracellular calcium (Ca2+)-dependent cysteine protease, is a modulator that governs various cellular functions. Hyperthermia induces an increase in cytosolic Ca2+ levels and triggers calpain activation. Contrastingly, pre-exposure of cells to mild hyperthermia induces thermotolerance due to the presence of cellular homeostatic processes such as heat shock response and autophagy. Recent studies suggest that calpain is a potential key molecule that links autophagy and apoptosis. In this review, we briefly introduce the regulation of intracellular Ca2+ homeostasis, basic features of calpains with their implications in cancer, immune responses, and the roles and cross-talk of calpains in cellular protection and cell death in hyperthermia.

The potential of gas plasma technology for targeting breast cancer

Despite therapeutic improvements in recent years, breast cancer remains an often fatal disease. In addition, breast cancer ulceration may occur during late stages, further complicating therapeutic or palliative interventions. In the past decade, a novel technology received significant attention in the medical field: gas plasma. This topical treatment relies on the partial ionization of gases that simultaneously produce a plethora of reactive oxygen and nitrogen species (ROS/RNS). Such local ROS/RNS overload inactivates tumour cells in a non-necrotic manner and was recently identified to induce immunogenic cancer cell death (ICD). ICD promotes dendritic cell maturation and amplifies antitumour immunity capable of targeting breast cancer metastases. Gas plasma technology was also shown to provide additive toxicity in combination with radio and chemotherapy and re-sensitized drug-resistant breast cancer cells. This work outlines the assets of gas plasma technology as a novel tool for targeting breast cancer by summarizing the action of plasma devices, the roles of ROS, signalling pathways, modes of cell death, combination therapies and immunological consequences of gas plasma exposure in breast cancer cells in vitro, in vivo, and in patient-derived microtissues ex vivo.

Distinct Cellular Tools of Mild Hyperthermia-Induced Acquired Stress Tolerance in Chinese Hamster Ovary Cells

Mild stress could help cells to survive more severe environmental or pathophysiological conditions. In the current study, we investigated the cellular mechanisms which contribute to the development of stress tolerance upon a prolonged (0-12 h) fever-like (40 °C) or a moderate (42.5 °C) hyperthermia in mammalian Chinese Hamster Ovary (CHO) cells. Our results indicate that mild heat triggers a distinct, dose-dependent remodeling of the cellular lipidome followed by the expression of heat shock proteins only at higher heat dosages. A significant elevation in the relative concentration of saturated membrane lipid species and specific lysophosphatidylinositol and sphingolipid species suggests prompt membrane microdomain reorganization and an overall membrane rigidification in response to the fluidizing heat in a time-dependent manner. RNAseq experiments reveal that mild heat initiates endoplasmic reticulum stress-related signaling cascades resulting in lipid rearrangement and ultimately in an elevated resistance against membrane fluidization by benzyl alcohol. To protect cells against lethal, protein-denaturing high temperatures, the classical heat shock protein response was required. The different layers of stress response elicited by different heat dosages highlight the capability of cells to utilize multiple tools to gain resistance against or to survive lethal stress conditions.

BH3-Only Proteins Noxa and Puma Are Key Regulators of Induced Apoptosis

Apoptosis is an evolutionarily conserved and tightly regulated cell death pathway. Physiological cell death is important for maintaining homeostasis and optimal biological conditions by continuous elimination of undesired or superfluous cells. The BH3-only pro-apoptotic members are strong inducers of apoptosis. The pro-apoptotic BH3-only protein Noxa activates multiple death pathways by inhibiting the anti-apoptotic Bcl-2 family protein, Mcl-1, and other protein members leading to Bax and Bak activation and MOMP. On the other hand, Puma is induced by p53-dependent and p53-independent apoptotic stimuli in several cancer cell lines. Moreover, this protein is involved in several physiological and pathological processes, such as immunity, cancer, and neurodegenerative diseases. Future heat shock research could disclose the effect of hyperthermia on both Noxa and BH3-only proteins. This suggests post-transcriptional mechanisms controlling the translation of both Puma and Noxa mRNA in heat-shocked cells. This study was also the chance to recapitulate the different reactional mechanisms investigated for caspases.

Streptococcus lutetiensis Induces Autophagy via Oxidative Stress in Bovine Mammary Epithelial Cells

Streptococcus lutetiensis, an emerging pathogen causing bovine mastitis, has not been well characterized. We reported that S. lutetiensis was pathogenic both in vivo and in vitro and caused inflammatory reactions in the mammary gland. However, roles of autophagy and oxidative stress in the pathogenesis of S. lutetiensis-induced mastitis are unclear. In this study, an autophagy model of S. lutetiensis-infected bovine mammary epithelial cells (bMECs) was used to assess oxidative stress and autophagy flux. Expressions of Beclin1, light chain 3II, and Sequestosome 1/p62 were elevated in bMECs after S. lutetiensis infection. In addition, autophagosome and lysosome formation confirmed autophagy occurred. Based on LysoTracker Red and acridine orange, lysosome degradation was blocked, and lower expressions of lysosomal-associated membrane protein 2, cathepsins D, and cathepsins L confirmed lysosomal damage. Concurrently, the nuclear factor erythroid 2-related factor 2 (Nrf2), kelch-like ECH-associated protein 1 (Keap1), heme oxygenase 1 (HO1), and NAD (P)H: quinone oxidoreductase 1 (NQO1), and basilic proteins associated with the Nrf2/Keap1 signaling pathway, were detected. Decreased keap1 and increased Nrf2, HO1, NQO1, and reactive oxygen species (ROS) indicated increased oxidative stress. Treatment with N-Acetyl-L-cysteine (NAC), an ROS inhibitor, decreased both oxidative stress and autophagy. Therefore, we concluded that S. lutetiensis caused intracellular oxidative stress and autophagy in bMECs. In addition, crosstalk between autophagy and oxidative stress affected the autophagic flux and blocked downstream autophagy. The Nrf2-keap1-p62 pathway participated in this process, with ROS acting upstream of these effects, interfering with normal cell functions.

A heat shock protein protects against oxidative stress induced by lambda-cyhalothrin in the green peach aphid Myzus persicae

Lambda-cyhalothrin (LCT) is a pyrethroid insecticide widely used to control insect pests. Insect exposure to LCT may cause abnormal accumulation of reactive oxygen species (ROS) and result in oxidative damage. Heat shock proteins (HSPs) may help protect against oxidative stress. However, little is known about the role of HSPs in response to LCT in the green peach aphid, Myzus persicae. This insect is an important agricultural pest causing severe yield losses in crops. In this study, we characterized a cDNA sequence (MpHsp70) encoding a member of the HSP70 family in M. persicae. MpHsp70 encoded a 623 amino acid protein putatively localized in the cytosol. The highest expression level of MpHsp70 occurred in fourth-instar nymphs. Treatment of M. persicae with LCT resulted in oxidative stress and significantly increased H₂O₂ and malondialdehyde levels. This led to an elevated transcription level of MpHsp70. Injection of H₂O₂ into M. persicae also upregulated the MpHsp70 expression level, suggesting that MpHsp70 is responsive to ROS, particularly H₂O₂, induced by LCT. Recombinant MpHSP70 protein was expressed in Escherichia coli. E. coli cells overexpressing MpHSP70 exhibited significant tolerance to H₂O₂ and the ROS generators, cumene hydroperoxide and paraquat. This indicated that MpHSP70 protects against oxidative stress. Furthermore, knockdown of MpHsp70 by RNA interference resulted in increased susceptibility in apterous adults of M. persicae to LCT. These findings indicate that MpHsp70 plays an important role in defense against LCT-induced oxidative stress and insecticide susceptibility in M. persicae.

ROS Pleiotropy in Melanoma and Local Therapy with Physical Modalities

Metabolic energy production naturally generates unwanted products such as reactive oxygen species (ROS), causing oxidative damage. Oxidative damage has been linked to several pathologies, including diabetes, premature aging, neurodegenerative diseases, and cancer. ROS were therefore originally anticipated as an imperative evil, a product of an imperfect system. More recently, however, the role of ROS in signaling and tumor treatment is increasingly acknowledged. This review addresses the main types, sources, and pathways of ROS in melanoma by linking their pleiotropic roles in antioxidant and oxidant regulation, hypoxia, metabolism, and cell death. In addition, the implications of ROS in various physical therapy modalities targeting melanoma, such as radiotherapy, electrochemotherapy, hyperthermia, photodynamic therapy, and medical gas plasma, are also discussed. By including ROS in the main picture of melanoma skin cancer and as an integral part of cancer therapies, a greater understanding of melanoma cell biology is presented, which ultimately may elucidate additional clues on targeting therapy resistance of this most deadly form of skin cancer.

Interactions between reactive oxygen species and autophagy: Special issue: Death mechanisms in cellular homeostasis

Oxidative stress is defined as "a serious imbalance between the generation of reactive oxygen species (ROS) and antioxidant defences in favour of ROS, causing excessive oxidative damage to biomolecules". Different stressors that induce autophagy, such as starvation and hypoxia, can increase production of ROS such as superoxide and hydrogen peroxide. This review provides brief summaries about oxidative stress and macroautophagy, and then considers current knowledge about the complex interactions between ROS and autophagy. ROS-induced autophagy could be a cellular protective mechanism that alleviates oxidative stress, or a destructive process. Increased ROS levels can regulate autophagy through several different pathways, such as activation of the AMPK signalling cascade and ULK1 complex, Atg4 oxidation, disruption of the Bcl-2/Beclin-1 interaction, and alteration of mitochondrial homeostasis leading to mitophagy. Autophagic degradation of Keap1 activates the antioxidant transcription factor Nrf2 and protects cells against ROS. Autophagy activation can, in turn, regulate oxidative stress by recycling damaged ROS-producing mitochondria. Macroautophagy plays an important role in degradation of large aggregates of oxidatively damaged/unfolded proteins, which are removed by the autophagy-lysosomal system. ROS can regulate autophagy, and in turn, autophagy can regulate oxidative stress. Future studies are necessary to improve understanding of the complex interactions between autophagy and oxidative stress.