Staurosporine-induced cleavage of alpha-smooth muscle actin during myofibroblast apoptosis

GPx1 deficiency confers increased susceptibility to ferroptosis in macrophages from individuals with active Crohn's disease

Intestinal cell death is a defining feature of Crohn's disease (CD), a major form of inflammatory bowel disease. The focus on this aspect of enteric inflammation has mainly been on epithelial cells, while other cell types such as stromal and myeloid cells have received less attention. Hypothesising that decreased macrophage viability in an oxidative environment could be a contributing factor to the pathophysiology of CD, we found that monocyte-derived macrophages from individuals with active CD (but not those in clinical disease remission) have increased sensitivity to cell death induced by H2O2. Molecular biology and pharmacological studies ruled out apoptosis and necroptosis, while increased lipid peroxidation and surface expression of the transferrin receptor implicated ferroptosis as the mechanism of the H2O2-induced cell death: this was supported by suppression of H2O2-cytotoxicity by liproxstatin-1, a pharmacological inhibitor of ferroptosis. Selenoproteins are important antioxidants, and selenium deficiency can be a feature of CD. Despite normal dietary intake of selenium, monocyte-derived macrophages and intestinal macrophages in individuals with CD had decreased protein and/or mRNA expression of the selenoprotein, glutathione peroxidase (GPx)-1. Knockdown of GPx1 in macrophages from healthy volunteers resulted in increased H2O2-induced cell death reminiscent of that observed with macrophages from CD. In summary, monocyte-derived macrophages from individuals with CD have increased susceptibility to H2O2-induced ferroptosis cell death, that may be facilitated, at least in part, by reduced expression of the antioxidant GPx1. We suggest that reduced GPx1 in monocytes recruited to the gut and intestinal macrophages renders these cells vulnerable to reactive oxygen species-evoked ferroptosis cell death and that unraveling the participation of this pathway in Crohn's disease may reveal novel therapeutic approaches to this chronic condition.

Activation of Yes-Associated Protein Is Indispensable for Transformation of Kidney Fibroblasts into Myofibroblasts during Repeated Administration of Cisplatin

Cisplatin is a potent chemotherapy medication that is used to treat various types of cancer. However, it can cause nephrotoxic side effects, which lead to acute kidney injury (AKI) and subsequent chronic kidney disease (CKD). Although a clinically relevant in vitro model of CKD induced by repeated administration of low-dose cisplatin (RAC) has been established, its underlying mechanisms remain poorly understood. Here, we compared single administration of high-dose cisplatin (SAC) to repeated administration of low-dose cisplatin (RAC) in myofibroblast transformation and cellular morphology in a normal rat kidney fibroblast NRK-49F cell line. RAC instead of SAC transformed the fibroblasts into myofibroblasts as determined by α-smooth muscle actin, enlarged cell size as represented by F-actin staining, and increased cell flattening as expressed by the semidiameter ratio of attached cells to floated cells. Those phenomena, as well as cellular senescence, were significantly detected from the time right before the second administration of cisplatin. Interestingly, inhibition of the interaction between Yes-associated protein (YAP) and the transcriptional enhanced associated domain (TEAD) using Verteporfin remarkedly reduced cell size, cellular senescence, and myofibroblast transformation during RAC. These findings collectively suggest that YAP activation is indispensable for cellular hypertrophy, senescence, and myofibroblast transformation during RAC in kidney fibroblasts.

Drug delivery systems for wound healing treatment of upper airway injury

INTRODUCTION

Endotracheal intubation is a common procedure to maintain an open airway with risks for traumatic injury. Pathological changes resulting from intubation can cause upper airway complications, including vocal fold scarring, laryngotracheal stenosis, and granulomas and present with symptoms such as dysphonia, dysphagia, and dyspnea. Current intubation-related laryngotracheal injury treatment approaches lack standardized guidelines, relying on individual clinician experience, and surgical and medical interventions have limitations and carry risks.

AREAS COVERED

The clinical and preclinical therapeutics for wound healing in the upper airway are described. This review discusses the current developments on local drug delivery systems in the upper airway utilizing particle-based delivery systems, including nanoparticles and microparticles, and bulk-based delivery systems, encompassing hydrogels and polymer-based approaches.

EXPERT OPINION

Complex laryngotracheal diseases pose challenges for effective treatment, struggling due to the intricate anatomy, limited access, and recurrence. Symptomatic management often requires invasive surgical procedures or medications that are unable to achieve lasting effects. Recent advances in nanotechnology and biocompatible materials provide potential solutions, enabling precise drug delivery, personalization, and extended treatment efficacy. Combining these technologies could lead to groundbreaking treatments for upper airways diseases, significantly improving patients' quality of life. Research and innovation in this field are crucial for further advancements.

Cytochrome c lysine acetylation regulates cellular respiration and cell death in ischemic skeletal muscle

Skeletal muscle is more resilient to ischemia-reperfusion injury than other organs. Tissue specific post-translational modifications of cytochrome c (Cytc) are involved in ischemia-reperfusion injury by regulating mitochondrial respiration and apoptosis. Here, we describe an acetylation site of Cytc, lysine 39 (K39), which was mapped in ischemic porcine skeletal muscle and removed by sirtuin5 in vitro. Using purified protein and cellular double knockout models, we show that K39 acetylation and acetylmimetic K39Q replacement increases cytochrome c oxidase (COX) activity and ROS scavenging while inhibiting apoptosis via decreased binding to Apaf-1, caspase cleavage and activity, and cardiolipin peroxidase activity. These results are discussed with X-ray crystallography structures of K39 acetylated (1.50 Å) and acetylmimetic K39Q Cytc (1.36 Å) and NMR dynamics. We propose that K39 acetylation is an adaptive response that controls electron transport chain flux, allowing skeletal muscle to meet heightened energy demand while simultaneously providing the tissue with robust resilience to ischemia-reperfusion injury.

Apoptotic Cell Death in Bicuspid-Aortic-Valve-Associated Aortopathy

The bicuspid aortic valve (BAV) is the most common cardiovascular congenital abnormality and is frequently associated with proximal aortopathy. We analyzed the tissues of patients with bicuspid and tricuspid aortic valve (TAV) regarding the protein expression of the receptor for advanced glycation products (RAGE) and its ligands, the advanced glycation end products (AGE), as well as the S100 calcium-binding protein A6 (S100A6). Since S100A6 overexpression attenuates cardiomyocyte apoptosis, we investigated the diverse pathways of apoptosis and autophagic cell death in the human ascending aortic specimen of 57 and 49 patients with BAV and TAV morphology, respectively, to identify differences and explanations for the higher risk of patients with BAV for severe cardiovascular diseases. We found significantly increased levels of RAGE, AGE and S100A6 in the aortic tissue of bicuspid patients which may promote apoptosis via the upregulation of caspase-3 activity. Although increased caspase-3 activity was not detected in BAV patients, increased protein expression of the 48 kDa fragment of vimentin was detected. mTOR as a downstream protein of Akt was significantly higher in patients with BAV, whereas Bcl-2 was increased in patients with TAV, assuming a better protection against apoptosis. The autophagy-related proteins p62 and ERK1/2 were increased in patients with BAV, assuming that cells in bicuspid tissue are more likely to undergo apoptotic cell death leading to changes in the wall and finally to aortopathies. We provide first-hand evidence of increased apoptotic cell death in the aortic tissue of BAV patients which may thus provide an explanation for the increased risk of structural aortic wall deficiency possibly underlying aortic aneurysm formation or acute dissection.

β-Elemene induces apoptosis by activating the P53 pathway in human hypertrophic scar fibroblasts

BACKGROUND

Hypertrophic scar (HS) is a condition characterized by excessive synthesis and deposition of collagen. There are many clinical methods to alleviate HS, but most of them are accompanied by many complications.

AIM OF THE STUDY

To investigate the effects of β-Elemene, extracted from the ginger family plant Wenyujin, on Human hypertrophic scar fibroblast.

MATERIALS AND METHODS

Cultured human hypertrophic scar fibroblast (hHSFs) and human normal fibroblasts (HF), and observed the effect of β-Elemene on apoptosis、extracellular matrix and endoplasmic reticulum stress by Western blot、RT-PCR and flow cytometry.

RESULTS

Based on our findings, it is clear that β-Elemene could inhibit the expression of α-SMA、collagen I and Fibronectin, reduced collagen deposition. Further studies had found that β-Elemene could increase the expression of endoplasmic reticulum stress (ERS)-related proteins CHOP and Calnexin in a dose-dependent manner, thereby promoting the aggregation of cleaved-caspase-3 and inducing hHSFs to undergo apoptosis. This process may depend on the regulation of P53.

CONCLUSIONS

The results of our study indicates that β-Elemene induced hHSFs to undergo apoptosis though ERS pathway in a P53-dependent manner, which means that our research provided a new strategy for the development of drugs for the treatment of HS. This article is protected by copyright. All rights reserved.

Synergistic effects of silver nanoparticles and cisplatin in combating inflammation and hyperplasia of airway stents

Anti-inflammatory and antihyperplasia activities are essential requirements for the successful use of airway stents. In this work, silver nanoparticles (AgNPs) and cisplatin (DDP) were combined in a synergistic modification strategy to improve the surface function of airway stents. Using polycaprolactone (PCL) as a drug carrier, a dual-functional PCL-AgNPs-DDP fiber film-coated airway stent was fabricated by electrospinning. The physicochemical and biological properties of the obtained fiber films were examined. The ATR-FTIR, XPS, SEM-EDS and TEM results suggested that AgNPs and DDP could be successfully immobilized onto the airway stent surface. The drug release and surface degradation results revealed that AgNPs and DDP can undergo sustained release from films for 30 d, and the weight loss was approximately 50% after 35 d. In addition, the dual-functional fiber film suppressed human embryonic lung fibroblast growth and exhibited excellent antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. Furthermore, the effectiveness of the dual-functional fiber film-coated airway stent was evaluated by application to the trachea of New Zealand rabbits. The in vivo results indicated that PCL-AgNPs-DDP fiber film-coated airway stent can significantly inhibit granulation tissue formation and collagen deposition, reduced the expression of IL-8, TNF-α, IL-1α, PCNA, α-SMA and CD68, and ultimately achieved anti-inflammatory and antihyperplasia effects. Hence, this study provides a dual-functional surface-coated airway stent to address the clinical complications associated with respiratory tract inflammation and granulation tissue hyperplasia, thus inhibiting tracheal stenosis.

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This study provides a dual-functional PCL-AgNPs-DDP nanofiber film-coated airway stent.

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The airway stent processes antibacterial activity and suppress CCC-HPF-1 growth.

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The stent inhibits tracheal stenosis by antiinflammatory and antihyperplasia treatment.

Hydrostatic pressure can induce apoptosis of the skin

We previously showed that high hydrostatic pressure (HHP) treatment at 200 MPa for 10 min induced complete cell death in skin and skin tumors via necrosis. We used this technique to treat a giant congenital melanocytic nevus and reused the inactivated nevus tissue as a dermis autograft. However, skin inactivated by HHP promoted inflammation in a preclinical study using a porcine model. Therefore, in the present study, we explored the pressurization conditions that induce apoptosis of the skin, as apoptotic cells are not believed to promote inflammation, so the engraftment of inactivated skin should be improved. Using a human dermal fibroblast cell line in suspension culture, we found that HHP at 50 MPa for ≥ 36 h completely induced fibroblast cell death via apoptosis based on the morphological changes in transmission electron microscopy, reactive oxygen species elevation, caspase activation and phosphatidylserine membrane translocation. Furthermore, immunohistochemistry with terminal deoxynucleotidyl transferase dUTP nick-end labeling and cleaved caspase-3 showed most cells in the skin inactivated by pressurization to be apoptotic. Consequently, in vivo grafting of apoptosis-induced inactivated skin resulted in successful engraftment and greater dermal cellular density and macrophage infiltration than our existing method. Our finding supports an alternative approach to hydrostatic pressure application.

The Antiproliferative and Antifibrotic Effects of Cisplatin on Primary Human Vocal Fold Fibroblasts

OBJECTIVE

Vocal fold scarring and laryngeal stenosis are major clinical challenges. Current drugs do not efficiently reduce scarring. We examined the antiproliferative and antifibrotic effects of cisplatin on primary human vocal fold fibroblasts (HVFFs).

METHODS

HVFFs were cultured in vitro and identified by immunocytochemistry. The relative viability of HVFFs was analyzed by Cell Counting Kit-8 assays (CCK-8). The fibrogenic phenotype was induced by transforming growth factor-β1 (TGF-β1) and reversed by cisplatin as shown by immunocytochemistry. Real-time PCR and Western blotting assessed collagen III and I. Western blotting for Smad2, p-Smad2, Smad-3, p-Smad3 and caspase-3 were performed.

RESULTS

CCK-8 results showed that cisplatin decreased the relative viability of HVFFs, and Western blots revealed elevation of the apoptosis-related protein caspase-3 in HVFFs. Cisplatin treatment reduced α-smooth muscle actin staining intensity in the presence of TGF-β1. Real-time PCR revealed the downregulation of collagen III and I in cisplatin-treated HVFFs. The TGF-β1-induced increased fibrogenic protein levels were decreased by cisplatin. Reduced levels were detected at late time points.

CONCLUSIONS

Cisplatin induces antiproliferative and antifibrotic alterations in HVFFs. Cisplatin may prevent postoperative vocal fold scarring and laryngeal stenosis in patients treated with CO2 laser microsurgery and undergoing delayed wound healing.

Acetylcholine decreases formation of myofibroblasts and excessive extracellular matrix production in an in vitro human corneal fibrosis model

Acetylcholine (ACh) has been reported to play various physiological roles, including wound healing in the cornea. Here, we study the role of ACh in the transition of corneal fibroblasts into myofibroblasts, and in consequence its role in the onset of fibrosis, in an in vitro human corneal fibrosis model. Primary human keratocytes were obtained from healthy corneas. Vitamin C (VitC) and transforming growth factor‐β1 (TGF‐β1) were used to induce fibrosis in corneal fibroblasts. qRT‐PCR and ELISA analyses showed that gene expression and production of collagen I, collagen III, collagen V, lumican, fibronectin (FN) and alpha‐smooth muscle actin (α‐SMA) were reduced by ACh in quiescent keratocytes. ACh treatment furthermore decreased gene expression and production of collagen I, collagen III, collagen V, lumican, FN and α‐SMA during the transition of corneal fibroblasts into myofibroblasts, after induction of fibrotic process. ACh inhibited corneal fibroblasts from developing contractile activity during the process of fibrosis, as assessed with collagen gel contraction assay. Moreover, the effect of ACh was dependent on activation of muscarinic ACh receptors. These results show that ACh has an anti‐fibrotic effect in an in vitro human corneal fibrosis model, as it negatively affects the transition of corneal fibroblasts into myofibroblasts. Therefore, ACh might play a role in the onset of fibrosis in the corneal stroma.

MiR-486-5p inhibits the hyperproliferation and production of collagen in hypertrophic scar fibroblasts via IGF1/PI3K/AKT pathway

Background: This study explored the function and mechanism of miR-486-5p in HSFBs.Methods: Qualitative real-time-polymerase chain reaction (qRT-PCR) was performed to detect the expression of miR-486-5p in HS and hypertrophic scar fibroblasts (HSFBs). Viability, migration, invasion ability, apoptosis, and expressions of Collagen I, Collagen III, α-SMA and Cleaved caspase-3 in HSFBs after transfection with miR-486-5p mimic or inhibitor were measured by CCK-8, wound-healing, transwell, and Western blot, respectively. Interaction between miR-486-5p and IGF1 was predicted by Targetscan version 7.2 and further confirmed by dual-luciferase assay, and functional rescue experiments were conducted to verify the predicted molecular mechanism. The activation of PI3K/AKT pathway was also analyzed by Western blot.Results: MiR-486-5p was low-expressed in HS and HSFBs, and that overexpression of miR-486-5p suppressed the viability, migration, invasion, and expressions of Collagen I, Collagen III, and α-SMA of HSFBs, meanwhile, it also promoted apoptosis and Cleaved caspase-3 expression in HSFBs. Moreover, IGF1 was targeted by miR-486-5p, and increased viability, migration, invasion, and collagens expressions, the activation of PI3K/Akt pathway, and decreased apoptosis and Cleaved caspase-3 induced by miR-486-5p inhibitor could be partly alleviated by siIGF1.Conclusions: Overexpressed miR-486-5p inhibited the hyperproliferation and excessive production of collagen in HSFBs via IGF1/PI3K/AKT pathway.

Death for life: a path from apoptotic signaling to tissue-scale effects of apoptotic epithelial extrusion

Apoptosis plays a crucial role in clearing old or critically compromised cells, and actively maintains epithelial homeostasis and epithelial morphogenesis during embryo development. But how is the apoptotic signaling pathway able to orchestrate such complex and dynamic multi-cellular morphological events at the tissue scale? In this review we collected the most updated knowledge regarding how apoptosis controls different cytoskeletal components. We describe how apoptosis can control epithelial homeostasis though epithelial extrusion, a highly orchestrated process based on high- order actomyosin structures and on the coordination between the apoptotic and the neighboring cells. Finally, we describe how the synergy among forces generated by multiple apoptotic cells can shape epithelia in embryo development.

Studies on sporadic non-syndromic thoracic aortic aneurysms: 1. Deregulation of Jagged/Notch 1 homeostasis and selection of synthetic/secretor phenotype smooth muscle cells

Background

Sporadic non-syndromic thoracic aortic aneurysms (SNSTAAs) are less well understood than familial non-syndromic or syndromic ones. The study aimed at defining the peculiar morphologic and molecular changes occurring in the media layer of SNSTAAs.

Design

This study was based on a single centre design.

Methods

Media layer samples taken from seven carefully selected SNSTAAs and seven reference patients (controls) were investigated via quantitative polymerase chain reaction, proteomics-bioinformatics, immunoblotting, quantitative histology, and immunohistochemistry/immunofluorescence.

Results

In SNSTAAs media, aortic smooth muscle cells numbers were halved due to an apoptotic process coupled with a negligible cell proliferation. Cystathionine γ-lyase was diffusely up-regulated. Surviving aortic smooth muscle cells exhibited diverging phenotypes: in inner- and outer-media contractile cells prevailed, having higher contents of smooth-muscle-α-actin holoprotein (45-kDa) and of caspase-3-cleaved smooth-muscle-α-actin 25-kDa fragments; in mid-media, aortic smooth muscle cells exhibited a synthetic/secretor phenotype, down-regulating vimentin, but up-regulating glial fibrillary acidic protein, trans-Golgi network 46 protein, Jagged1 (172-kDa) holoprotein, and Jagged1’s receptor Notch1. Extracellular soluble Jagged1 (42-kDa) fragments accumulated.

Conclusions

In SNSTAAs, there is a relentless aortic smooth muscle cells attrition caused by the up-regulated cystathionine γ-lyase. In mid-media, synthetic/secretor aortic smooth muscle cells intensify Jagged1/NOTCH1 signalling in the attempt to counterbalance the weakened aortic wall, due to aortic smooth muscle cells net loss and mechanical stress. Synthetic/secretor aortic smooth muscle cells are apoptosis-prone, and the accruing thrombin-cleaved Jagged1 fragments counteract the otherwise useful effects of Jagged1/NOTCH1 signalling, thus hampering tissue homeostasis/remodelling, and aortic smooth muscle cells adhesion, differentiation, and migration.

Deferiprone inhibits iron overload-induced tissue factor bearing endothelial microparticle generation by inhibition oxidative stress induced mitochondrial injury, and apoptosis

Iron overload-induced cardiovascular toxicity is one of the most common causes of morbidity and mortality in beta-thalassemia major patients. We have previously shown that iron overload-induced systemic arterial changes characterized by endothelial dysfunction are associated with increased endothelial microparticle (EMP) release. In this study, we further demonstrate how EMP release is associated with iron-induced mitochondrial injury and apoptosis of endothelial cells. Iron increased the production of reactive oxygen species (ROS) and calcium influx into mitochondria [Ca²⁺]_m. Iron also disturbed mitochondrial respiration function and eventually led to loss of mitochondrial membrane potential (ΔΨ_m). A significant increase in apoptotic cells and EMPs were found under iron treatment. EMPs contained tissue factor (TF), which has potential clinical impact on thromboembolic phenomenon. Then, we investigated the salvaging effect of deferiprone (L1) on endothelial cell damage and EMP release. We found that L1 could inhibit iron-induced ROS generation, and decrease mitochondrial damage with the resultant effect of less endothelial cell apoptosis and EMP release. L1 could protect endothelial cells from iron-induced toxic effects and minimize EMP release, which could be potentially helpful in a subgroup of thalassemia patients who have increased thromboembolic complications.

Effects of Photodynamic Therapy Using Yellow LED-light with Concomitant Hypocrellin B on Apoptotic Signaling in Keloid Fibroblasts

Keloid is a common and refractory disease characterized by abnormal fibroblast proliferation and excessive deposition of extracellular matrix components. Hypocrellin B (HB) is a natural perylene quinone photosensitizer. In this experiment, we studied the effects of photodynamic therapy (PDT) using yellow light from light-emitting diode (LED) combined with HB on keloid fibroblasts (KFB) in vitro. Our results showed that HB-LED PDT treatment induced significant KFB apoptosis and decreased KFB cell viability. HB-LED PDT treatment lead to significant BAX upregulation and BCL-2 downregulation in KFB cells, which led to elevation of intracellular free Ca²⁺ and activation of caspase-3. Our data provides preliminary evidence for the potential of HB-LED PDT as a therapeutic strategy for keloid.

Paraquat induces epithelial-mesenchymal transition-like cellular response resulting in fibrogenesis and the prevention of apoptosis in human pulmonary epithelial cells

The aim of this study is to investigate the molecular mechanisms underlying delayed progressive pulmonary fibrosis, a characteristic of subacute paraquat (PQ) poisoning. Epithelial-mesenchymal transition (EMT) has been proposed as a cause of organ fibrosis, and transforming growth factor-β (TGF-β) is suggested to be a powerful mediator of EMT. We thus examined the possibility that EMT is involved in pulmonary fibrosis during PQ poisoning using A549 human alveolar epithelial cells in vitro. The cells were treated with various concentrations of PQ (0–500 μM) for 2–12 days. Short-term (2 days) high-dose (>100 μM) treatments with PQ induced cell death accompanied by the activation of caspase9 as well as a decrease in E-cadherin (an epithelial cell marker), suggesting apoptotic cell death with the features of anoikis (cell death due to the loss of cell-cell adhesion). In contrast, long-term (6–12 days) low-dose (30 μM) treatments with PQ resulted in a transformation into spindle-shaped mesenchymal-like cells with a decrease of E-cadherin as well as an increase of α-smooth muscle actin (α-SMA). The mesenchymal-like cells also secreted the extracellular matrix (ECM) protein fibronectin into the culture medium. The administration of a TGF-β1 receptor antagonist, SB431542, almost completely attenuated the mesenchymal transformation as well as fibronectin secretion, suggesting a crucial role of TGF-β1 in EMT-like cellular response and subsequent fibrogenesis. It is noteworthy that despite the suppression of EMT-fibrogenesis, apoptotic death was observed in cells treated with PQ+SB431542. EMT-like cellular response and subsequent fibrogenesis were also observed in normal human bronchial epithelial (NHBE) cells exposed to PQ in a TGF-β1-dependent manner. Taken together, our experimental model reflects well the etiology of PQ poisoning in human and shows the involvement of EMT-like cellular response in both fibrogenesis and resistance to cell death during subacute PQ poisoning of pulmonary epithelial cells.

Dynamic processes that reflect anti-apoptotic strategies set up by HspB1 (Hsp27)

Human HspB1 (also denoted Hsp27) is an oligomeric anti-apoptotic protein that has tumorigenic and metastatic roles. To approach the structural organizations of HspB1 that are active in response to apoptosis inducers acting through different pathways, we have analyzed the relative protective efficiency induced by this protein as well its localization, oligomerization and phosphorylation. HeLa cells, that constitutively express high levels of HspB1 were treated with either etoposide, Fas agonist antibody, staurosporine or cytochalasin D. Variability in HspB1 efficiency to interfere with the different apoptotic transduction pathways induced by these agents were detected. Moreover, inducer-specific dynamic changes in HspB1 localization, native size and phosphorylation were observed, that differed from those observed after heat shock. Etoposide and Fas treatments gradually shifted HspB1 towards large but differently phosphorylated oligomeric structures. In contrast, staurosporine and cytochalasin D induced the rapid but transient formation of small oligomers before large structures were formed. These events correlated with inducer-specific phosphorylations of HspB1. Of interest, the formation of small oligomers in response to staurosporine and cytochalasin D was time correlated with the rapid disruption of F-actin. The subsequent, or gradual in the case of etoposide and Fas, formation of large oligomeric structures was a later event concomitant with the early phase of caspase activation. These observations support the hypothesis that HspB1 has the ability, through specific changes in its structural organization, to adapt and interfere at several levels with challenges triggered by different signal transduction pathways upstream of the execution phase of apoptosis.

The herbal medicine inchin-ko-to (TJ-135) induces apoptosis in cultured rat hepatic stellate cells

Use of herbal remedies in the treatment of various diseases has a long tradition in Eastern medicine and the liver diseases are not an exception. In their use, lack of elucidation of mechanism(s) as well as randomized, placebo-controlled clinical trials has been a problem. Recently, we and others reported that inchin-ko-to (TJ-135), one of herbal remedies, suppressed hepatic fibrosis in animal models. In the course of clarifying the mechanism, we directed our focus on hepatic stellate cells (HSCs), playing a pivotal role in hepatic fibrosis, and found that rat HSCs cultured with TJ-135 changed their morphology to star-like configuration with thin, slender and dendritic processes with fewer stress fibers, which might be the features in apoptosis. In fact, TJ-135 induced HSC apoptosis in a time- and concentration-dependent manner as judged by the nuclear morphology, quantitation of cytoplasmic histone-associated DNA oligonucleosome fragments and caspase 3 activity. In HSCs treated with TJ-135, increased expression of p53 and decreased expression of Bcl-2 and phosphorylated Akt and Bad were determined. HSC apoptosis is shown to be involved in the mechanisms of spontaneous resolution of rat hepatic fibrosis and the agent which induces HSC apoptosis has been shown to reduce experimental hepatic fibrosis in rats. Thus, the induction of HSC apoptosis could be the mechanism how TJ-135 works on the resolution of hepatic fibrosis. Our current data may shed light on the novel effect of the herbal remedy.

Beta-actin is required for mitochondria clustering and ROS generation in TNF-induced, caspase-independent cell death

Tumor necrosis factor (TNF)-alpha induces caspase-independent cell death in the fibrosarcoma cell line L929. This cell death has a necrotic phenotype and is dependent on production of reactive oxygen species (ROS) in the mitochondria. To identify genes involved in this TNF-induced, ROS-dependent cell death pathway, we utilized retrovirus insertion-mediated random mutagenesis to generate TNF-resistant L929 cell lines and we subsequently identified genes whose mutations are responsible for the TNF-resistant phenotype. In one such resistant line, beta-actin was disrupted by viral insertion, and subsequent reconstitution of beta-actin expression levels in the mutant line Actin(mut) restored its sensitivity to TNF. Resistance to TNF in Actin(mut) cells is signal specific since the sensitivity to other death stimuli is either unchanged or even increased. Comparable NF-kappaB activation and p38 phosphorylation in TNF-treated wild-type and Actin(mut) cells also indicates that reduced expression of actin only selectively blocked some of the TNF-induced cellular changes. Actin cleavage involved in apoptosis does not occur in TNF-treated L929 cell death, as in HeLa cells. Consistent over-expression of a caspase-cleaved product, a 15 kDa actin fragment, had no effect on TNF-induced necrosis of L929 cell. By contrast, TNF-induced mitochondria clustering and ROS production were dramatically reduced in Actin(mut) cells, indicating that actin-deficiency-mediated TNF resistance is most likely due to impaired mitochondrial responses to TNF stimulation. Our findings suggest that a full complement of actin is required for transduction of a cell death signal to mitochondria in TNF-treated L929 cells.

PKC412 induces apoptosis through a caspase-dependent mechanism in human keloid-derived fibroblasts

There is no established pharmacological therapy for skin keloids, a wound healing disorder. In this study, we investigated the effect of N-benzoyl staurosporine (PKC412), a protein kinase C inhibitor, on human keloid-derived fibroblasts to examine whether this agent is applicable for the treatment of keloid formation. Although PKC412 induced apoptosis in keloid fibroblasts in a time- and dose-dependent manner, the effective concentration of this agent was much higher than that of staurosporine. Western blotting showed that both PKC412 (10 microM) and staurosporine (100 nM) cleaved pro-caspase-3 to active forms. An in vitro caspase assay also showed that PKC412 and staurosporine elevated caspase-3 activities. Carbobenzoxy-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-FMK), a caspase inhibitor with a broad spectrum, inhibited caspase-3 activities stimulated by PKC412 and staurosporine; however, only PKC412-induced apoptosis, but not staurosporine-induced apoptosis, was prevented by Z-VAD-FMK. These results suggested that PKC412-induced apoptosis, but not staurosporine-induced apoptosis, is mainly mediated by the caspase-dependent mechanism.

Metronidazole induces programmed cell death in the protozoan parasite Blastocystis hominis

Previous studies by the authors have shown that the protozoan parasite Blastocystis hominis succumbed to a cytotoxic monoclonal antibody with a number of cellular and biochemical features characteristic of apoptosis in higher eukaryotes. The present study reports that apoptosis-like features are also observed in growing cultures of axenic B. hominis upon exposure to metronidazole, a drug commonly used for the treatment of blastocystosis. Upon treatment with the drug, B. hominis cells displayed key morphological and biochemical features of programmed cell death (PCD), viz. nuclear condensation and nicked DNA in nucleus, reduced cytoplasmic volume, externalization of phosphatidylserine and maintenance of plasma membrane integrity with increasing permeability. This present study also supports the authors' previously postulated novel function for the B. hominis central vacuole in PCD; it acts as a repository where apoptotic bodies are stored before being released into the extracellular space. The implications and possible roles of PCD in B. hominis are discussed.