Endoplasmic reticulum chaperone GRP78 mediates cigarette smoke-induced necroptosis and injury in bronchial epithelium

Endoplasmic reticulum stress mediates environmental particle-induced inflammatory response in bronchial epithelium

While the detailed mechanisms for how particulate matter (PM) causes adverse health effects in the lungs remain largely unknown, endoplasmic reticulum (ER) stress has been implicated in PM-induced lung injury. The present study was undertaken to examine how/if ER stress might regulate PM-induced inflammation, and to begin to define potential underlying molecular mechanisms. Here, ER stress hallmarks were examined in human bronchial epithelial (HBE) cells exposed to PM. To confirm roles of certain pathways, siRNA targeting ER stress genes and an ER stress inhibitor were employed. Expression of select inflammatory cytokines and related signaling pathway components by the cells were assessed as well. The results showed that PM exposure induced elevations in two ER stress hallmarks, i.e. GRP78 and IRE1α, in time-and/or dose-related manners in the HBE cells. Inhibition of ER stress by siRNA for GRP78 or IRE1α significantly alleviated the PM-induced effects. Further, ER stress appeared to regulate PM-induced inflammation - likely through downstream autophagy and NF-κB pathways - as implied by studies showing that inhibition of ER stress by siRNA of GRP78 or IRE1α caused significant amelioration of PM-induced autophagy and subsequent activation of NF-κB pathways. Moreover, the ER stress inhibitor 4-PBA were used to confirm the protective effects against PM-induced outcomes. Together, the results suggest ER stress plays a deleterious role in PM-induced airway inflammation, possibly through activation of autophagy and NF-κB signaling. Accordingly, protocols/treatments that could lead to inhibited ER stress could potentially be effective for treatment of PM-related airway disorders.

Resolution Potential of Necrotic Cell Death Pathways

During tissue damage caused by infection or sterile inflammation, not only damage-associated molecular patterns (DAMPs), but also resolution-associated molecular patterns (RAMPs) can be activated. These dying cell-associated factors stimulate immune cells localized in the tissue environment and induce the production of inflammatory mediators or specialized proresolving mediators (SPMs). Within the current prospect of science, apoptotic cell death is considered the main initiator of resolution. However, more RAMPs are likely to be released during necrotic cell death than during apoptosis, similar to what has been observed for DAMPs. The inflammatory potential of many regulated forms of necrotic cell death modalities, such as pyroptosis, necroptosis, ferroptosis, netosis, and parthanatos, have been widely studied in necroinflammation, but their possible role in resolution is less considered. In this review, we aim to summarize the relationship between necrotic cell death and resolution, as well as present the current available data regarding the involvement of certain forms of regulated necrotic cell death in necroresolution.

Role of necroptosis in airflow limitation in chronic obstructive pulmonary disease: focus on small-airway disease and emphysema

Airflow limitation with intractable progressive mechanisms is the main disease feature of chronic obstructive pulmonary disease (COPD). The pathological process of airflow limitation in COPD involves necroptosis, a form of programmed necrotic cell death with pro-inflammatory properties. In this paper, the correlations of small-airway disease and emphysema with airflow limitation in COPD were firstly reviewed; then, based on this, the effects of necroptosis on small-airway disease and emphysema were analysed, and the possible mechanisms of necroptosis causing airflow limitation in COPD were explored. The results showed that airflow limitation is caused by a combination of small-airway disease and emphysema. In addition, toxic particulate matter stimulates epithelial cells to trigger necroptosis, and necroptosis promotes the expulsion of cell contents, the abnormal hyperplasia of pro-inflammatory mediators and the insufficient clearance of dead cells by macrophages; these processes, coupled with the interaction of necroptosis and oxidative stress, collectively result in small-airway disease and emphysema in COPD.

Cryptotanshinone alleviates myocardial ischemia and reperfusion injury in rats to mitigate ER stress-dependent apoptosis by modulating the JAK1/STAT3 axis

OBJECTIVE

Myocardial ischemia is the stoppage or insufficiency of blood flow to the myocardium, depriving cells of oxygen supply which leads to their apoptosis or death. Currently, the management of patients has improved, making it possible to reduce myocardial infarction injury with new strategies of reperfusion and pharmacologic treatment.

METHODS

A rat model of myocardial ischemia and reperfusion injury (MIRI) was created and subjected to cryptotanshinone (CRY) with or without JAK1 inhibitor filgotinib (FILGO) treatment. H&E staining was used for histopathologic evaluation of heart injury, and TTC staining was employed for evaluation of the infarct size. Western blotting and immunofluorescence were used to measure the protein expression and qRT-PCR for determining mRNA expression.

RESULTS

CRY significantly reduced the area of the infarct, the number of apoptotic cells, and the concentrations of lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) induced by ischemia/reperfusion (I/R). Subsequent analysis showed that CRY repressed the expression of caspase-12, CHOP, and GRP78, but enhanced the phosphorylation of JAK and STAT3. However, FILGO treatment markedly abolished the beneficial effect of CRY pretreatment on cardiomyocyte damage, apoptosis, cardiac function, and inhibition of endoplasmic reticulum stress (ERS)-dependent apoptosis marker proteins.

CONCLUSION

CRY may alleviate MIRI by inhibiting ERS-dependent apoptosis by activating the JAK1/STAT3 signaling pathway.

Pathogenesis of COPD at the cellular and molecular level

Chronic inflammatory responses in the lung of patients with stable mild-to severe forms of COPD play a central role in the definition, comprehension and monitoring of the disease state. A better understanding of the COPD pathogenesis can't avoid a detailed knowledge of these inflammatory changes altering the functional health of the lung during the disease progression. We here summarize and discuss the role and principal functions of the inflammatory cells populating the large, small airways and lung parenchyma of patients with COPD of increasing severity in comparison with healthy control subjects: T and B lymphocytes, NK and Innate Lymphoid cells, macrophages, and neutrophils. The differential inflammatory distribution in large and small airways of patients is also discussed. Furthermore, relevant cellular mechanisms controlling the homeostasis and the "normal" balance of these inflammatory cells and of structural cells in the lung, such as autophagy, apoptosis, necroptosis and pyroptosis are as well presented and discussed in the context of the COPD severity.

Dysregulation of the miR-30a/BiP axis by cigarette smoking accelerates oral cancer progression

Background

Cigarette smoking is the most significant cause of oral cancer progression. Cigarette smoke condensate (CSC) has been shown to induce endoplasmic reticulum (ER) stress. Binding immunoglobulin protein (BiP) being as an ER stress regulator, has been reported to be implicated in malignant behaviors. Therefore, the aim of this study was to investigate the role of the ER stress-responsive protein, BiP, in CSC-induced oral squamous cell carcinoma (OSCC) malignancy.

Methods

The biological role of BiP in CSC-induced tumor progression was investigated in OSCC cells (YD38 and SCC25) and in a tumor xenograft mouse model. The expressions of related genes were investigated using quantitative RT-PCR and Western blot analysis. Cell migration and invasion were assessed using scratch wound healing and Transwell invasion assays. The effects of conditioned media from OSCC cells on the angiogenic activities of endothelial cells were analyzed using a tube formation assay. The interaction between miR-30a and BiP mRNA was detected using a luciferase reporter assay.

Results

Our results demonstrated that CSC increased the expression of BiP in time- and dose-dependent manners in YD38 and SCC25 cells, and that silencing BiP abrogated CSC-induced cell invasion and tumor-associated angiogenesis. Notably, the putative miR-30a binding site was observed in the 3′untranslated region (UTR) of BiP mRNA, and miR-30a suppressed BiP expression by targeting 3′UTR of BiP transcript. In addition, CSC increased the expression of BiP in OSCC cells by downregulating miR-30a. We also showed that BiP promoted invasion and tumor-associated angiogenesis by increasing the production and secretion of vascular endothelial growth factor in CSC-exposed OSCC cells. Moreover, BiP inhibition suppressed OSCC growth and reduced tumor vessel density in tumor-bearing mice administered with CSC.

Conclusions

These observations suggest that epigenetic regulation of BiP via miR-30a downregulation is involved in CSC-induced OSCC progression.

Necroptosis in Pulmonary Diseases: A New Therapeutic Target

In the past decades, apoptosis has been the most well-studied regulated cell death (RCD) that has essential functions in tissue homeostasis throughout life. However, a novel form of RCD called necroptosis, which requires receptor-interacting protein kinase-3 (RIPK3) and mixed-lineage kinase domain-like pseudokinase (MLKL), has recently been receiving increasing scientific attention. The phosphorylation of RIPK3 enables the recruitment and phosphorylation of MLKL, which oligomerizes and translocates to the plasma membranes, ultimately leading to plasma membrane rupture and cell death. Although apoptosis elicits no inflammatory responses, necroptosis triggers inflammation or causes an innate immune response to protect the body through the release of damage-associated molecular patterns (DAMPs). Increasing evidence now suggests that necroptosis is implicated in the pathogenesis of several human diseases such as systemic inflammation, respiratory diseases, cardiovascular diseases, neurodegenerative diseases, neurological diseases, and cancer. This review summarizes the emerging insights of necroptosis and its contribution toward the pathogenesis of lung diseases.

Necroptosis Signalling Promotes Inflammation, Airway Remodelling and Emphysema in COPD

RATIONALE

Necroptosis, mediated by RIPK3 and MLKL, is a form of regulated necrosis that can drive tissue inflammation and destruction, however its contribution to COPD pathogenesis is poorly understood.

OBJECTIVES

To determine the role of necroptosis in COPD.

METHODS

Levels of RIPK3, MLKL and activated phospho-MLKL were measured in lung tissues of COPD patients and non-COPD controls. Necroptosis-related mRNA and proteins and cell death were examined in the lungs and pulmonary macrophages of mice with cigarette smoke (CS)-induced experimental COPD. The responses of Ripk3- and Mlkl-deficient (-/-) mice to CS exposure were compared to wild-type mice. Combined inhibition of apoptosis (pan-caspase inhibitor qVD-OPh) and necroptosis (Mlkl-/- mice) was assessed.

MEASUREMENTS AND MAIN RESULTS

Protein levels of MLKL and pMLKL but not RIPK3 were increased in lung tissues of COPD patients compared to never smokers or smoker non-COPD controls. Necroptosis-related mRNA and protein levels were increased in lung tissue and macrophages in CS-exposed mice/experimental COPD. Ripk3 or Mlkl deletion prevented airway inflammation in response to acute CS-exposure. Ripk3 deficiency reduced airway inflammation and remodelling and development of emphysematous pathology following chronic CS-exposure. Mlkl deletion and qVD-OPh treatment reduced chronic CS-induced airway inflammation, but only Mlkl deletion prevented airway remodelling and emphysema. Ripk3 or Mlkl deletion and qVD-OPh treatment reduced CS-induced lung cell death.

CONCLUSIONS

Necroptosis is induced by CS exposure and increased in COPD patient lungs and experimental COPD. Inhibiting necroptosis attenuates CS-induced airway inflammation, airway remodelling and emphysema. Targeted inhibition of necroptosis is a potential therapeutic strategy in COPD.

The potential role of necroptosis in clinical diseases (Review)

As an important type of programmed cell death in addition to apoptosis, necroptosis occurs in a variety of pathophysiological processes, including infections, liver diseases, kidney injury, neurodegenerative diseases, cardiovascular diseases, and human tumors. It can be triggered by a variety of factors, such as tumor necrosis factor receptor and Toll‑like receptor families, intracellular DNA and RNA sensors, and interferon, and is mainly mediated by receptor‑interacting protein kinase 1 (RIP1), RIP3, and mixed lineage kinase domain‑like protein. A better understanding of the mechanism of necroptosis may be useful in the development of novel drugs for necroptosis‑related diseases. In this review, the focus is on the molecular mechanisms of necroptosis, exploring the role of necroptosis in different pathologies, discussing their potential as a novel therapeutic target for disease therapy, and providing suggestions for further study in this area.

TFIIB-related factor 2 regulates glucose-regulated protein 78 expression in acquired middle ear cholesteatoma

Acquired middle ear cholesteatoma leads to hearing loss, ear discharge, ear pain, and more serious intracranial complications. However, there is still no effective treatment other than surgery. TFIIB-related factor 2 (BRF2) acted as a redox sensor overexpressing in oxidative stress which linked endoplasmic reticulum (ER) stress, while glucose-regulated protein 78 (GRP78) was a biomarker of ER stress in cancer, atherosclerosis and inflammation. In our study, we investigated the roles of BRF2 and GRP78 in acquired middle ear cholesteatoma. Our results revealed that the expression of BRF2 was significant increased in acquired middle ear cholesteatoma, and which was positively correlated with the expression of GRP78. In addition, BRF2 and GRP78 showed colocalization in epithelium of acquired middle ear cholesteatomas and HaCaT cells. Prolongation of LPS stimulation in HaCaT cells escalated the expression of BRF2 and GRP78. To confirm the role of BRF2 and GRP78, we transfected si-BRF2 into HaCaT cells. All results indicated that BRF2 expression positively regulates the expression of GRP78 and may participate in the pathogenesis of acquire middle ear cholesteatoma.

Necroptosis Mediates Cigarette Smoke-Induced Inflammatory Responses in Macrophages

Introduction

Cigarette smoke (CS)-induced inflammation in macrophages is involved in the pathological process of chronic obstructive pulmonary disease (COPD). Necroptosis, which is a form of programmed necrosis, has a close relationship with robust inflammation, while its roles in COPD are unclear.

Materials and Methods

Necroptosis markers were measured in mouse alveolar macrophages and cultured bone marrow-derived macrophages (BMDMs). Necroptosis inhibitors were used to block necroptosis in BMDMs, and inflammatory cytokines were detected. We further explored the related signaling pathways.

Results

In this study, we demonstrated the way in which necroptosis, in addition to its upstream and downstream signals, regulates CS-induced inflammatory responses in macrophages. We observed that CS exposure caused a significant increase in the levels of necroptosis markers (receptor interacting kinases [RIPK] 1 and 3) in mouse alveolar macrophages and BMDMs. Pharmacological inhibition of RIPK1 or 3 caused a significant suppression in CS extract (CSE)-induced inflammatory cytokines, chemokine ligands (CXCL) 1 and 2, and interleukin (IL)-6 in BMDMs. CSE-induced necroptosis was regulated by mitochondrial reactive oxygen species (mitoROS), which also promoted inflammation in BMDMs. Furthermore, necroptosis regulated CSE-induced inflammatory responses in BMDMs, most likely through activation of the nuclear factor-κB pathway.

Conclusion

Taken together, our results demonstrate that mitoROS-dependent necroptosis is essential for CS-induced inflammation in BMDMs and suggest that inhibition of necroptosis in macrophages may represent effective therapeutic approaches for COPD patients.

Molecular Chaperones in Neurodegeneration

Cellular chaperones are essential players to this protein quality control network that functions to prevent protein misfolding, refold misfolded proteins, or degrade them, thereby maintaining neuronal proteostasis. Moreover, overexpression of cellular chaperones is considered to inhibit protein aggregation and apoptosis in various experimental models of neurodegeneration. Alterations or downregulation of chaperone machinery by age-related decline, molecular crowding, or genetic mutations are regarded as key pathological hallmarks of neurodegenerative disorders like Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and Prion diseases. Therefore, chaperones may serve as potential therapeutic targets in these diseases. This chapter presents a generalized view of misfolding and aggregation of proteins in neurodegeneration and then critically analyses some of the known cellular chaperones and their role in several neurodegenerative disorders.

The roles of Nrf2 and autophagy in modulating inflammation mediated by TLR4 - NFκB in A549 cell exposed to layer house particulate matter 2.5 (PM2.5)

Particulate matter (PM) from layer house has adverse effect on people and chicken respiratory health, which can further influence animal performance and reduce production efficiency. However, little study focus on the respiratory inflammation induced by PM_2.5 from layer house and the underlying mechanism also unclear. In this study, human adenocarcinoma alveolar basal epithelial cells (A549 cell) was subjected to the PM_2.5 from layer house to evaluate the inflammation reaction caused by PM_2.5 and explore the role of Nrf2 and autophagy in regulating the inflammation. Results showed that the viability of A549 cell decreased in a time - and concentration - dependent manner after PM_2.5 treatment. TNFα, IL6, and IL8 increased significantly treated with PM_2.5 at 12 h. RNA sequencing indicated differentially expressed genes were enriched in immune system process, oxidative stress (OS), endoplasmic reticulum stress (ERS), and autophagy. Further studies showed TLR4 - NFκB p65 signal pathway involved in the inflammation reaction caused by PM_2.5. The overexpression of Nrf2 decreased the level of TNFα, IL6, IL8 markedly as well as the level of NFκB p65 and NFκB pp65. OS and ERS were also limited under overactivation of Nrf2 in PM_2.5 treated cells. Autophagy induced by PM_2.5 promoted the inflammation through increasing the level of NFκB p65 and NFκB pp65. Autophagy deficient strengthened the expression of Nrf2. Collectively, our study revealed Nrf2 prevents inflammation caused by layer house PM_2.5 stimulation, however, autophagy exerts a promotive role in TLR4 - NFκB p65 mediating inflammation in A549 cell.

Pathogenesis of chronic obstructive pulmonary disease (COPD) induced by cigarette smoke

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease that is characterized by functional and structural alterations primarily caused by long-term inhalation of harmful particles. Cigarette smoke (CS) induces airway inflammation in COPD, which is known to persist even after smoking cessation. This review discusses the basic pathogenesis of COPD, with particular focus on an endogenous protective mechanism against oxidative stress via Nrf2, altered immune response of the airway inflammatory cells, exaggerated cellular senescence of the lung structural cells, and cell death with expanded inflammation. Recently, CS-induced mitochondria autophagy is reported to initiate programmed necrosis (necroptosis). Necroptosis is a new concept of cell death which is driven by a defined molecular pathway along with exaggerated inflammation. This new cell death mechanism is of importance due to its ability to produce more inflammatory substances during the process of epithelial death, contributing to persistent airway inflammation that cannot be explained by apoptosis-derived cell death. Autophagy is an auto-cell component degradation system executed by lysosomes that controls protein and organelle degradation for successful homeostasis. As well as in the process of necroptosis, autophagy is also observed during cellular senescence. Aging of the lungs results in the acquisition of senescence-associated secretory phenotypes (SASP) that are known to secrete inflammatory cytokines, chemokines, growth factors, and matrix metalloproteinases resulting in chronic low-grade inflammation. In future research, we intend to highlight the genetic and epigenetic approaches that can facilitate the understanding of disease susceptibility. The goal of precision medicine is to establish more accurate diagnosis and treatment methods based on the patient-specific pathogenic characteristics. This review provides insights into CS-induced COPD pathogenesis, which contributes to a very complex disease. Investigating the mechanism of developing COPD, along with the availability of the particular inhibitors, will lead to new therapeutic approaches in COPD treatment.

Estrogen administration reduces the risk of pulmonary arterial hypertension by modulating the miR-133a signaling pathways in rats

We aimed to investigate how estrogen (ES) is implicated in the pathogenesis of pulmonary arterial hypertension (PAH) potentially by reducing the extent of vascular remodeling in females. HE assay, Western Blot, IHC, and real-time PCR were carried out to observe the role of ES in regulating miR-133a expression and the levels of MYOSLID, SRF, CTGF, and vascular remodeling in rats. In addition, MTT assay and flow cytometry were utilized to observe how ES affects cell proliferation and cell cycle in PAH. Moreover, luciferase assays were carried out to clarity the regulatory relationship between miR-133a and its downstream targets. ES administration relieved the deregulation of miR-133a, MYOSLID, SRF, and CTGF in PAH rats. In addition, ES also reduced the thickening of blood vessels in PAH rats. ES could activate miR-133a promoter and arrest the cells in the G0/G1 cycle, thus dose-dependently suppressing the proliferation of cells. In addition, the presence of ES, MYOSLID siRNA, or miR-133a precursor all altered the expression of MYOSLID, SP1, SRF, and CTGF, thus establishing a molecular signaling pathway among these factors. Furthermore, miR-133a could bind to SP1, MYOSLID, SRF, and CTGF to reduce their expression. Moreover, SRF was proved to function as an activator of miR-133a promoter. Two feedback loops were established in this study: a negative feedback loop between SRF and miR-133a, and a positive loop among miR-133a/SRF/MLK1/MYOSLID. ES treatment upregulates miR-133a expression and reduces the incidence of PAH and vascular remodeling.

Autophagy in exposure to environmental chemicals

Autophagy is a catabolic pathway, which breaks down old and damaged cytoplasmic material into basic biomolecules through lysosome-mediated digestion thereby recycling cellular material. In this way, autophagy prevents the accumulation of damaged cellular components inside cells and reduces metabolic stress and toxicity. The basal level of autophagy is generally low but essential for maintaining the turnover of proteins and other molecules. The level is, however, increased in response to various stress conditions including chemical stress. This elevation in autophagy is intended to restore energy balance and improve cell survival in stress conditions. However, aberrant and/or deficient autophagy may also be involved in the aggravation of chemical-caused insults. Thus, the overall role of autophagy in chemical-induced toxicity is complex and only a limited number of environmental chemicals have been studied from this point of view. Autophagy is associated with many of the chemical-caused cytotoxic mechanisms, including mitochondrial dysfunction, DNA damage, oxidative stress, changes in the endoplasmic reticulum, impairment of lysosomal functions, and inflammation. This mini-review describes autophagy and its involvement in the responses to some common environmental exposures including airborne particulate matter, nanoparticles and tobacco smoke as well as to some common single environmental chemicals.

Autophagy, selective autophagy, and necroptosis in COPD

COPD is characterized by persistent respiratory symptoms and airflow limitation, caused by a mixture of small airway disease and pulmonary emphysema. Programmed cell death has drawn the attention of COPD researchers because emphysema is thought to result from epithelial cell death caused by smoking. Although apoptosis has long been thought to be the sole form of programmed cell death, recent studies have reported the existence of a genetically programmed and regulated form of necrosis called necroptosis. Autophagy was also previously considered a form of programmed cell death, but this has been reconsidered. However, recent studies have revealed that autophagy can regulate programmed cell death, including apoptosis and necroptosis. It is also becoming clear that autophagy can selectively degrade specific proteins, organelles, and invading bacteria by a process termed “selective autophagy” and that this process is related to the pathogenesis of human diseases. In this review, we outline the most recent studies implicating autophagy, selective autophagy, and necroptosis in COPD. Strategies targeting these pathways may yield novel therapies for COPD.