scholarly journals Apoptosis and inflammation

1995 ◽  
Vol 4 (1) ◽  
pp. 5-15 ◽  
Author(s):  
C. Haanen ◽  
I. Vermes
Keyword(s):  
Cell Death ◽  
Inflammatory Reaction ◽  
Inflammatory Diseases ◽  
Apoptotic Cell ◽  
Cell Damage ◽  
Target Cells ◽  
Apoptotic Bodies ◽  
Accidental Injury ◽  
Inflammatory Reactions ◽  
Inflammatory Processes

During the last few decades it has been recognized that cell death is not the consequence of accidental injury, but is the expression of a cell suicide programme. Kerr et al. (1972) introduced the term apoptosis. This form of cell death is under the influence of hormones, growth factors and cytokines, which depending upon the receptors present on the target cells, may activate a genetically controlled cell elimination process. During apoptosis the cell membrane remains intact and the cell breaks into apoptotic bodies, which are phagocytosed. Apoptosis, in contrast to necrosis, is not harmful to the host and does not induce any inflammatory reaction. The principal event that leads to inflammatory disease is cell damage, induced by chemical/physical injury, anoxia or starvation. Cell damage means leakage of cell contents into the adjacent tissues, resulting in the capillary transmigration of granulocytes to the injured tissue. The accumulation of neutrophils and release of enzymes and oxygen radicals enhances the inflammatory reaction. Until now there has been little research into the factors controlling the accumulation and the tissue load of granulocytes and their histotoxic products in inflammatory processes. Neutrophil apoptosis may represent an important event in the control of intlamtnation. It has been assumed that granulocytes disintegrate to apoptotic bodies before their fragments are removed by local macrophages. Removal of neutrophils from the inflammatory site without release of granule contents is of paramount importance for cessation of inflammation. In conclusion, apoptotic cell death plays an important role in inflammatory processes and in the resolution of inflammatory reactions. The facts known at present should stimulate further research into the role of neutrophil, eosinophil and macrophage apoptosis in inflammatory diseases.

scholarly journals Autophagy impairment as a key feature for acetaminophen-induced ototoxicity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tong Zhao ◽  
Tihua Zheng ◽  
Huining Yu ◽  
Bo Hua Hu ◽  
Bing Hu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Lysosomal Enzymes ◽  
Apoptotic Cell ◽  
Cell Damage ◽  
Treatment Strategies ◽  
Explant Culture ◽  
Apoptotic Cell Death ◽  
Lysosomal Dysfunction ◽  
Autophagic Degradation

AbstractMacroautophagy/autophagy is a highly conserved self-digestion pathway that plays an important role in cytoprotection under stress conditions. Autophagy is involved in hepatotoxicity induced by acetaminophen (APAP) in experimental animals and in humans. APAP also causes ototoxicity. However, the role of autophagy in APAP-induced auditory hair cell damage is unclear. In the present study, we investigated autophagy mechanisms during APAP-induced cell death in a mouse auditory cell line (HEI-OC1) and mouse cochlear explant culture. We found that the expression of LC3-II protein and autophagic structures was increased in APAP-treated HEI-OC1 cells; however, the degradation of SQSTM1/p62 protein, the yellow puncta of mRFP-GFP-LC3 fluorescence, and the activity of lysosomal enzymes decreased in APAP-treated HEI-OC1 cells. The degradation of p62 protein and the expression of lysosomal enzymes also decreased in APAP-treated mouse cochlear explants. These data indicate that APAP treatment compromises autophagic degradation and causes lysosomal dysfunction. We suggest that lysosomal dysfunction may be directly responsible for APAP-induced autophagy impairment. Treatment with antioxidant N-acetylcysteine (NAC) partially alleviated APAP-induced autophagy impairment and apoptotic cell death, suggesting the involvement of oxidative stress in APAP-induced autophagy impairment. Inhibition of autophagy by knocking down of Atg5 and Atg7 aggravated APAP-induced ER and oxidative stress and increased apoptotic cell death. This study provides a better understanding of the mechanism responsible for APAP ototoxicity, which is important for future exploration of treatment strategies for the prevention of hearing loss caused by ototoxic medications.

Fas-based d1OS-mediated cytotoxicity requires macromolecular synthesis for effector cell activation but not for target cell death

1994 ◽  
Vol 345 (1313) ◽  
pp. 303-309 ◽  
Keyword(s):  
Cell Death ◽  
T Cell ◽  
Cell Surface ◽  
Target Cell ◽  
Cell Activation ◽  
Effector Cell ◽  
Apoptotic Cell ◽  
Target Cells ◽  
Macromolecular Synthesis ◽  
Effector Cells

Two main mechanisms seem at play in T cell-mediated cytotoxicity, a process in which target cell death often follows an apoptotic cell death pattern. One of these involves Fas at the target cell surface and a Fas ligand at the effector cell surface. This allowed us to reinvestigate the long-standing question of macromolecular synthesis requirement in T cell-mediated cytotoxicity, using the dlOS model cell line which is cytotoxic apparently only via the Fas molecularly defined mechanism. We showed, first, that induction of cytotoxic activity of effector cells, obtained by preincubating these effector cells with a phorbol ester and a calcium ionophore, could be inhibited by macromolecular synthesis inhibitors (cycloheximide, actinomycin D, DRB). We then investigated whether macromolecular synthesis was required, when effector and target cells were mixed, to obtain target cell death. Preincubating already activated effector cells for 30 min with macromolecular synthesis inhibitors, then adding target cells and performing the 51 Cr release cytotoxicity test in the presence of these inhibitors, did not significantly decrease subsequent target cell death, indicating that already activated effector cells could kill without further requirement for macromolecular synthesis. In addition, target cell preincubation for up to 3 h in the presence of one of these inhibitors did not decrease cell death. The high sensitivity of mouse thymocytes to this type of cytotoxicity enabled us to devise the following experiment. As previously shown by others, thymocyte death induced by dexamethasone (DEX) could be blocked by coincubation with cycloheximide (CHX). Such DEX-treated CHX-rescued thymocytes, the survival of which was an internal control of efficiency of protein synthesis inhibition, were then subjected to effector cells in the presence of CHX, and were shown to die. Thus, there is no requirement for macromolecular synthesis at the target cell level in this variety of apoptotic cell death. Altogether, in this defined mechanism of T cell-mediated cytotoxicity, macromolecular synthesis is required for dlOS effector cell activation, but not for lysis by already activated effector cells nor for target cell death.

scholarly journals Apolipoprotein M is required for the protective effects of high density lipoprotein against ischemia-induced astrocyte apoptosis

2021 ◽  
Author(s):  
Xiaojia Huang ◽  
Zhiqi Zhai ◽  
Ting Zhou ◽  
Chengju Sheng ◽  
Chao Zhou ◽  
...  
Keyword(s):  
Cell Death ◽  
High Density Lipoprotein ◽  
Apoptotic Cell ◽  
Density Lipoprotein ◽  
Glucose Deprivation ◽  
High Density ◽  
Target Cells ◽  
Protective Effects ◽  
Apolipoprotein M ◽  
Sphingosine 1 Phosphate

Abstract Objectives High density lipoprotein (HDL) has been reported to show protective effects against cell death. Apolipoprotein M (ApoM) in HDL can bind with sphingosine-1-phosphate (S1P) and deliver S1P to target cells. This study aimed to evaluate the effects of HDL on astrocyte apoptosis after ischemic insult and determine the role of ApoM.Methods After ApoM-associated HDL (HDLapoM+) and ApoM-depleted HDL(HDLapoM-) were separated from mouse plasma, primary cultured mouse astrocytes were chellenged with oxygen-glucose deprivation followed by recovery in presence of HDLapoM+ or HDLapoM-. mRNA and protein samples were collected for biochemical analysis.Results The addition of HDLapoM+ attenuated apoptotic cell death in the astrocytes, but HDLapoM- did not show any effect. S1P receptor 1 (S1PR1) expression was upregulated, and specific S1PR1 inhibitor or genetic knockdown of S1pr1 abolished the protective effects. In addition, activation of Akt and ERK was induced by HDLapoM+ or free S1P, and pharmacological inhibition of Akt and ERK reduced the protection of HDLapoM+.Conclusions ApoM is essential for the protective effects of HDL, which depends on S1PR1 activation and downstream activation of Akt/ERK, Thus, ApoM may be a neuroprotective component in plasma.

scholarly journals Activation of α7-nAChRs Promotes the Clearance of α-Synuclein and Protects Against Apoptotic Cell Death Induced by Exogenous α-Synuclein Fibrils

2021 ◽  
Vol 9 ◽  
Author(s):  
Jifeng Zhao ◽  
Yun Li ◽  
Yan Li ◽  
Shi Xu ◽  
Tingting Tao ◽  
...  
Keyword(s):  
Cell Death ◽  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Apoptotic Cell ◽  
Cell Damage ◽  
Neuroprotective Effect ◽  
Cholinergic Neurons ◽  
Apoptotic Cell Death ◽  
Mammalian Brain ◽  
Α7 Nachrs

Misfolding and abnormal aggregation of α-synuclein (αSyn) have been shown to increase the risk of developing Parkinson's disease (PD). Finding some way to reduce the aggregation of αSyn is particularly important for the treatment of PD. The main route in prion-like αSyn spreading is the cholinergic innervated vagus nervous system and central cholinergic neurons. Since the degenerative changes and death of cholinergic neurons also run through the pathological process of PD, we hypothesize an involvement of the cholinergic system in αSyn aggregation. The α7 nicotinic acetylcholine receptors (α7-nAChRs) are one of the most abundant nAChRs in the mammalian brain. Using nicotine and a selective α7-nAChRs agonist PNU-282987, we found a protective effect of α7-nAChRs on the cell damage induced by αSyn-PFF (preformed fibrils) through inhibiting apoptotic cell death. We further discovered an additive effect of α7-nAChRs on the clearance of αSyn in normal and αSyn stably transduced SH-SY5Y cells. Moreover, using α7-nAChRs knockout mice, we noticed that α7-nAChRs deficiency increased the deposition of αSyn and aggravated the loss of dopaminergic neurons in a chronic MPTP mouse model of PD. Our findings for the first time indicated that α7-nAChRs activation exhibited a neuroprotective effect on αSyn pathology and aggregation by promoting the clearance of αSyn.

scholarly journals Apoptotic cell-derived exosomes: messages from dying cells

2020 ◽  
Vol 52 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Ramesh Kakarla ◽  
Jaehark Hur ◽  
Yeon Ji Kim ◽  
Jaeyoung Kim ◽  
Yong-Joon Chwae
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Immune Responses ◽  
Extracellular Vesicles ◽  
Apoptotic Cell ◽  
Active Form ◽  
Live Cells ◽  
Apoptotic Bodies ◽  
Pathological Conditions ◽  
Dying Cells

AbstractApoptosis, a type of programmed cell death that plays a key role in both healthy and pathological conditions, releases extracellular vesicles such as apoptotic bodies and microvesicles, but exosome release due to apoptosis is not yet commonly accepted. Here, the reports demonstrating the presence of apoptotic exosomes and their roles in inflammation and immune responses are summarized, together with a general summary of apoptosis and extracellular vesicles. In conclusion, apoptosis is not just a ‘silent’ type of cell death but an active form of communication from dying cells to live cells through exosomes.

scholarly journals Antiinflammatory Effects of CD95 Ligand (FasL)-induced Apoptosis

1998 ◽  
Vol 188 (5) ◽  
pp. 887-896 ◽  
Author(s):  
Yakun Gao ◽  
John M. Herndon ◽  
Hui Zhang ◽  
Thomas S. Griffith ◽  
Thomas A. Ferguson
Keyword(s):  
Cell Death ◽  
Apoptotic Cell ◽  
Apoptotic Cell Death ◽  
Lymphoid Cells ◽  
Apoptotic Cells ◽  
Immune Deviation ◽  
Inflammatory Reactions ◽  
Cd95 Ligand ◽  
Induced Apoptosis

Apoptosis is critical to homeostasis of multicellular organisms. In immune privileged sites such as the eye, CD95 ligand (FasL)-induced apoptosis controls dangerous inflammatory reactions that can cause blindness. Recently, we demonstrated that apoptotic cell death of inflammatory cells was a prerequisite for the induction of immune deviation after antigen presentation in the eye. In this report, we examine the mechanism by which this takes place. Our results show that Fas- mediated apoptosis of lymphoid cells leads to rapid production of interleukin (IL)-10 in these cells. The apoptotic cells containing IL-10 are responsible for the activation of immune deviation through interaction with antigen-presenting cells (APC). In support of this, we found that apoptotic cells from IL-10+/+ animals fed to APC in vitro promote Th2 cell differentiation, whereas apoptotic IL-10−/− cells, as well as nonapoptotic cells, favor Th1 induction. Thus, apoptotic cell death and tolerance are linked through the production of an antiinflammatory cytokine to prevent dangerous and unwanted immune responses that might compromise organ integrity.

MRP8/MRP14 impairs endothelial integrity and induces a caspase-dependent and -independent cell death program

Blood ◽  
2006 ◽  
Vol 109 (6) ◽  
pp. 2453-2460 ◽  
Author(s):  
Dorothee Viemann ◽  
Katarzyna Barczyk ◽  
Thomas Vogl ◽  
Ute Fischer ◽  
Cord Sunderkötter ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cell Death ◽  
Dna Fragmentation ◽  
Calcium Binding ◽  
Inflammatory Diseases ◽  
Membrane Damage ◽  
Death Receptor ◽  
Mitochondrial Pathway ◽  
Endothelial Damage ◽  
Target Cells

Abstract Activated phagocytes express considerable amounts of MRP8 and MRP14, 2 calcium-binding S100 proteins forming stable heterodimers that are specifically secreted at inflammatory sites in many diseases. We previously reported that treatment of human microvascular endothelial cells with purified MRP8/MRP14 leads to loss of endothelial cell contacts. In this study, we demonstrate that MRP8/MRP14 complexes furthermore trigger cell death of endothelial cells after the onset of cell detachment. Morphologic analysis of dying endothelial cells revealed characteristic features of both apoptosis and necrosis. Furthermore, MRP8/MRP14 induced apoptotic caspase-9 and caspase-3 activation, DNA fragmentation, and membrane phosphatidylserine exposure in target cells. These events were independent of death receptor signaling and in part controlled by a mitochondrial pathway. Consistently, overexpression of antiapoptotic Bcl-2 abrogated caspase activation and externalization of phosphatidylserine; however, MRP8/MRP14 still induced plasma membrane damage and even DNA fragmentation. Thus, our results demonstrate that MRP8/MRP14 triggers cell death via caspase-dependent as well as -independent mechanisms. Excessive release of cytotoxic MRP8/MRP14 by activated phagocytes might therefore present an important molecular pathomechanism contributing to endothelial damage during vasculitis and other inflammatory diseases.

scholarly journals Ladostigil attenuates the oxidative and ER stress in human neuroblast-like SH-SY5Y cells

2021 ◽  
Author(s):  
Keren Zohar ◽  
Elyad Lezmi ◽  
Tsiona Eliyahu ◽  
Michal Linial
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Er Stress ◽  
Microglial Activation ◽  
Cell Cycle Progression ◽  
Apoptotic Cell ◽  
Cell Damage ◽  
Aging Brain ◽  
Er Quality Control ◽  
Chronic Oxidative Stress

A hallmark of the aging brain is the robust inflammation mediated by microglial activation. Neuroinflammation resulting from the induction of oxidative stress in neurodegenerative diseases and following brain injury. Chronic treatment of aging rats by ladostigil, a compound with antioxidant and anti-inflammatory function, prevented microglial activation and learning deficits. In this study, we investigate the effect of ladostigil on neuronal-like SH-SY5Y cells. We show that SH-SY5Y cells exposed to acute (by H2O2) or chronic oxidative stress (by Sin1, 3-morpholinosydnonimine) induced apoptotic cell death. However, in the presence of ladostigil, the decline in cell viability and the oxidative levels were partially reversed. RNA-seq analysis showed that chronic oxidation by Sin1 resulted in coordinated suppression of endoplasmic reticulum (ER) quality control and ER stress response gene sets. Chronic oxidative stress impacted ER proteostasis and induced the expression of numerous lncRNAs. Pre-incubation with ladostigil before exposing SH-SY5Y cells to Sin1 induced Clk1 (Cdc2-like kinase 1) which was implicated in psychophysiological stress in mice and Alzheimer disease. Ladostigil also suppressed the expression of Ccpg1 (Cell cycle progression 1) and Synj1 (Synaptojanin 1) that function in ER-autophagy and endocytic pathways. We postulate that ladostigil alleviated cell damage by oxidation and ER stress. Therefore, it may attenuate neurotoxicity and cell death that accompany chronic stress conditions in the aging brain.

scholarly journals Hyperkalaemia, not apoptosis, accurately predicts insect chilling injury

2020 ◽  
Vol 287 (1941) ◽  
pp. 20201663
Author(s):  
Jessica Carrington ◽  
Mads Kuhlmann Andersen ◽  
Kaylen Brzezinski ◽  
Heath A. MacMillan
Keyword(s):  
Cell Death ◽  
Low Temperature ◽  
Thermal Tolerance ◽  
Caspase 3 ◽  
Apoptotic Cell ◽  
Cell Damage ◽  
Locusta Migratoria ◽  
Chilling Injury ◽  
Thermal Adaptation ◽  
Migratory Locust

There is a growing appreciation that insect distribution and abundance are associated with the limits of thermal tolerance, but the physiology underlying thermal tolerance remains poorly understood. Many insects, like the migratory locust ( Locusta migratoria ), suffer a loss of ion and water balance leading to hyperkalaemia (high extracellular [K + ]) in the cold that indirectly causes cell death. Cells can die in several ways under stress, and how they die is of critical importance to identifying and understanding the nature of thermal adaptation. Whether apoptotic or necrotic cell death pathways are responsible for low-temperature injury is unclear. Here, we use a caspase-3 specific assay to indirectly quantify apoptotic cell death in three locust tissues (muscle, nerves and midgut) following prolonged chilling and recovery from an injury-inducing cold exposure. Furthermore, we obtain matching measurements of injury, extracellular [K + ] and muscle caspase-3 activity in individual locusts to gain further insight into the mechanistic nature of chilling injury. We found a significant increase in muscle caspase-3 activity, but no such increase was observed in either nervous or gut tissue from the same animals, suggesting that chill injury primarily relates to muscle cell death. Levels of chilling injury measured at the whole animal level, however, were strongly correlated with the degree of haemolymph hyperkalaemia, and not apoptosis. These results support the notion that cold-induced ion balance disruption triggers cell death but also that apoptosis is not the main form of cell damage driving low-temperature injury.

Dose- and time-dependent effects of TNFα and actinomycin D on cell death incidence and embryo growth in mouse blastocysts

Zygote ◽  
2007 ◽  
Vol 15 (3) ◽  
pp. 241-249 ◽  
Author(s):  
D. Fabian ◽  
S. Juhás ◽  
G. Il'ková ◽  
J. Koppel
Keyword(s):  
Cell Death ◽  
Caspase 3 ◽  
Actinomycin D ◽  
Culture Media ◽  
Apoptotic Cell ◽  
Cell Damage ◽  
Time Dependent ◽  
Preimplantation Embryos ◽  
Induced Apoptosis

SummaryThis study was undertaken to obtain information about characteristics of different types of induced apoptosis in preimplantation embryos. Freshly isolated mouse blastocysts were cultured in vitro with the addition of two apoptotic inductors – TNFα and actinomycin D – at various doses and times. The average number of nuclei and the percentage of dead cells were evaluated in treated embryos. Classification of dead cells was based on morphological assessment of their nuclei evaluated by fluorescence microscopy, the detection of specific DNA degradation (TUNEL assay), the detection of active caspase-3 and cell viability assessed by propidium iodide staining. The addition of both apoptotic inductors into culture media significantly increased cell death incidence in blastocysts. Their effects were dose and time dependent. Lower concentrations of inductors increased cell death incidence, usually without affecting embryo growth after 24 h culture. Higher concentrations of inductors caused wider cell damage and also retarded embryo development. In all experiments, the negative effect of actinomycin D on blastomere survival and blastocyst growth was greater than the effect of TNFα. Furthermore, the addition of actinomycin D into culture media increased cell death incidence even after 6 h culture. Differences resulted probably from diverse specificity of apoptotic inductors. The majority of dead cells in treated blastocysts were of apoptotic origin. Morphological and biochemical features of apoptotic cell death induced by both TNFα and actinomycin D were similar and had homologous profile. In blastomeres, similarly to somatic cells, the biochemical pathways of induced apoptosis included activation of caspase-3 and internucleosomal DNA fragmentation.

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