Inflammation and Monocyte Recruitment due to Aging and Mechanical Stretch in Alveolar Epithelium are Inhibited by the Molecular Chaperone 4-phenylbutyrate

Astaxanthin and meclizine extend lifespan in UM-HET3 male mice; fisetin, SG1002 (hydrogen sulfide donor), dimethyl fumarate, mycophenolic acid, and 4-phenylbutyrate do not significantly affect lifespan in either sex at the doses and schedules used

In genetically heterogeneous (UM-HET3) mice produced by the CByB6F1 × C3D2F1 cross, the Nrf2 activator astaxanthin (Asta) extended the median male lifespan by 12% (p = 0.003, log-rank test), while meclizine (Mec), an mTORC1 inhibitor, extended the male lifespan by 8% (p = 0.03). Asta was fed at 1840 ± 520 (9) ppm and Mec at 544 ± 48 (9) ppm, stated as mean ± SE (n) of independent diet preparations. Both were started at 12 months of age. The 90th percentile lifespan for both treatments was extended in absolute value by 6% in males, but neither was significant by the Wang-Allison test. Five other new agents were also tested as follows: fisetin, SG1002 (hydrogen sulfide donor), dimethyl fumarate, mycophenolic acid, and 4-phenylbutyrate. None of these increased lifespan significantly at the dose and method of administration tested in either sex. Amounts of dimethyl fumarate in the diet averaged 35% of the target dose, which may explain the absence of lifespan effects. Body weight was not significantly affected in males by any of the test agents. Late life weights were lower in females fed Asta and Mec, but lifespan was not significantly affected in these females. The male-specific lifespan benefits from Asta and Mec may provide insights into sex-specific aspects of aging.

Tensile Overload Injures Human Alveolar Epithelial Cells through YAP/F-Actin/MAPK Signaling

BACKGROUND

Explosion shockwaves can generate overloaded mechanical forces and induce lung injuries. However, the mechanism of lung injuries caused by tensile overload is still unclear.

METHODS

Flow cytometry was used to detect the apoptosis of human alveolar epithelial cells (BEAS-2B) induced by tensile overload, and cell proliferation was detected using 5-ethynyl-2'-deoxyuridine (EdU). Immunofluorescence and Western blot analysis were used to identify the tensile overload on the actin cytoskeleton, proteins related to the mitogen-activated protein kinase (MAPK) signal pathway, and the Yes-associated protein (YAP).

RESULTS

Tensile overload reduced BEAS-2B cell proliferation and increased apoptosis. In terms of the mechanism, we found that tensile overload led to the depolymerization of the actin cytoskeleton, the activation of c-Jun N-terminal kinase (JNK) and extracellular-signal-regulated kinase 1/2 (ERK1/2), and the upregulation of YAP expression. Jasplakinolide (Jasp) treatment promoted the polymerization of the actin cytoskeleton and reduced the phosphorylation of tension-overload-activated JNK and ERK1/2 and the apoptosis of BEAS-2B cells. Moreover, the inhibition of the JNK and ERK1/2 signaling pathways, as well as the expression of YAP, also reduced apoptosis caused by tensile overload.

CONCLUSION

Our study establishes the role of the YAP/F-actin/MAPK axis in tensile-induced BEAS-2B cell injury and proposes new strategies for the treatment and repair of future lung injuries.

Pulmonary endogenous progenitor stem cell subpopulation: Physiology, pathogenesis, and progress

Lungs are structurally and functionally complex organs consisting of diverse cell types from the proximal to distal axis. They have direct contact with the external environment and are constantly at risk of various injuries. Capable to proliferate and differentiate, pulmonary endogenous progenitor stem cells contribute to the maintenance of lung structure and function both under homeostasis and following injuries. Discovering candidate pulmonary endogenous progenitor stem cell types and underlying regenerative mechanisms provide insights into therapeutic strategy development for lung diseases. In this review, we reveal their compositions, roles in lung disease pathogenesis and injury repair, and the underlying mechanisms. We further underline the advanced progress in research approach and potential therapy for lung regeneration. We also demonstrate the feasibility and prospects of pulmonary endogenous stem cell transplantation for lung disease treatment.

Topical phenylbutyrate antagonizes NF-κB signaling and resolves corneal inflammation

Chronic inflammation of the immune privileged cornea originating from viral or nonviral conditions results in significant vision loss. Topical corticosteroids are the common treatments for corneal inflammation, but the drugs cause serious and potentially blinding side effects in the long term. Therefore, new standalone and/or synergistic anti-inflammatory therapies with lower side effects are desperately needed. Here, we show that the aromatic fatty acid phenylbutyrate (PBA) acts as a potent inhibitor of inflammation in preclinical ocular-inflammation models. PBA prevents the transcription as well as translation of pro-inflammatory cytokines by LPS and poly(I:C) via persistent inhibition of NF-κB signaling. PBA quickens the resolution of ocular inflammation in mice by decreasing corneal thickness and immune cell infiltration. More importantly, PBA can synergize with the dexamethasone to antagonize NF-κB signaling at lower drug concentrations. Our results demonstrate that PBA therapy exerts previously unreported anti-inflammatory effects in the eye and facilitates corneal healing during persistent inflammation.

Chronic Bedridden Condition Is Reflected by Substantial Changes in Plasma Inflammatory Profile

Absent or reduced physical activity and spontaneous movement over days, weeks, or even years may lead to problems in almost every major organ/system in the human body. In this study, we investigated whether the dysregulation and alteration of plasma protein inflammatory profiling can stratify chronic bedridden conditions observed in 22 elderly chronic bedridden (CBR) individuals with respect to 11 age-matched active (OLD) controls. By using a combination of immune-assay multiplex techniques, a complex of 27 inflammatory mediators was assessed in the plasma collected from the two groups. A specific plasma protein signature is indeed able to distinguish IPO individuals from age-matched OLD controls; while significantly (p < 0.001) higher protein levels of IL-2, IL-7, and IL-12p70 were measured in the plasma of CBR with respect to OLD individuals, significantly (p < 0.01) higher levels of seven inflammatory mediators, including IL-9, PDGF-b, CCL4 (MIP-1b), CCL5 (RANTES), IL-1Ra, CXCL10 (IP10), and CCL2 (MCP-1), were identified in OLD individuals with respect to CBR individuals. These data suggest that the chronic absence of physical activity may contribute to the dysregulation of a complex molecular pattern occurring with ageing and that specific plasma protein signatures may represent potential biomarkers as well as new potential therapeutic targets for new treatments aimed at improving health expectancy.

Emerging Glycation-Based Therapeutics-Glyoxalase 1 Inducers and Glyoxalase 1 Inhibitors

The abnormal accumulation of methylglyoxal (MG) leading to increased glycation of protein and DNA has emerged as an important metabolic stress, dicarbonyl stress, linked to aging, and disease. Increased MG glycation produces inactivation and misfolding of proteins, cell dysfunction, activation of the unfolded protein response, and related low-grade inflammation. Glycation of DNA and the spliceosome contribute to an antiproliferative and apoptotic response of high, cytotoxic levels of MG. Glyoxalase 1 (Glo1) of the glyoxalase system has a major role in the metabolism of MG. Small molecule inducers of Glo1, Glo1 inducers, have been developed to alleviate dicarbonyl stress as a prospective treatment for the prevention and early-stage reversal of type 2 diabetes and prevention of vascular complications of diabetes. The first clinical trial with the Glo1 inducer, trans-resveratrol and hesperetin combination (tRES-HESP)-a randomized, double-blind, placebo-controlled crossover phase 2A study for correction of insulin resistance in overweight and obese subjects, was completed successfully. tRES-HESP corrected insulin resistance, improved dysglycemia, and low-grade inflammation. Cell permeable Glo1 inhibitor prodrugs have been developed to induce severe dicarbonyl stress as a prospective treatment for cancer-particularly for high Glo1 expressing-related multidrug-resistant tumors. The prototype Glo1 inhibitor is prodrug S-p-bromobenzylglutathione cyclopentyl diester (BBGD). It has antitumor activity in vitro and in tumor-bearing mice in vivo. In the National Cancer Institute human tumor cell line screen, BBGD was most active against the glioblastoma SNB-19 cell line. Recently, potent antitumor activity was found in glioblastoma multiforme tumor-bearing mice. High Glo1 expression is a negative survival factor in chemotherapy of breast cancer where adjunct therapy with a Glo1 inhibitor may improve treatment outcomes. BBGD has not yet been evaluated clinically. Glycation by MG now appears to be a pathogenic process that may be pharmacologically manipulated for therapeutic outcomes of potentially important clinical impact.

Mechanotransduction Regulates the Interplays Between Alveolar Epithelial and Vascular Endothelial Cells in Lung

Mechanical stress plays a critical role among development, functional maturation, and pathogenesis of pulmonary tissues, especially for the alveolar epithelial cells and vascular endothelial cells located in the microenvironment established with vascular network and bronchial-alveolar network. Alveolar epithelial cells are mainly loaded by cyclic strain and air pressure tension. While vascular endothelial cells are exposed to shear stress and cyclic strain. Currently, the emerging evidences demonstrated that non-physiological mechanical forces would lead to several pulmonary diseases, including pulmonary hypertension, fibrosis, and ventilation induced lung injury. Furthermore, a series of intracellular signaling had been identified to be involved in mechanotransduction and participated in regulating the physiological homeostasis and pathophysiological process. Besides, the communications between alveolar epithelium and vascular endothelium under non-physiological stress contribute to the remodeling of the pulmonary micro-environment in collaboration, including hypoxia induced injuries, endothelial permeability impairment, extracellular matrix stiffness elevation, metabolic alternation, and inflammation activation. In this review, we aim to summarize the current understandings of mechanotransduction on the relation between mechanical forces acting on the lung and biological response in mechanical overloading related diseases. We also would like to emphasize the interplays between alveolar epithelium and vascular endothelium, providing new insights into pulmonary diseases pathogenesis, and potential targets for therapy.

Advanced Glycation End Products Are Retained in Decellularized Muscle Matrix Derived from Aged Skeletal Muscle

Decellularized tissues are biocompatible materials that engraft well, but the age of their source has not been explored for clinical translation. Advanced glycation end products (AGEs) are chemical cross-links that accrue on skeletal muscle collagen in old age, stiffening the matrix and increasing inflammation. Whether decellularized biomaterials derived from aged muscle would suffer from increased AGE collagen cross-links is unknown. We characterized gastrocnemii of 1-, 2-, and 20-month-old C57BL/6J mice before and after decellularization to determine age-dependent changes to collagen stiffness and AGE cross-linking. Total and soluble collagen was measured to assess if age-dependent increases in collagen and cross-linking persisted in decellularized muscle matrix (DMM). Stiffness of aged DMM was determined using atomic force microscopy. AGE levels and the effect of an AGE cross-link breaker, ALT-711, were tested in DMM samples. Our results show that age-dependent increases in collagen amount, cross-linking, and general stiffness were observed in DMM. Notably, we measured increased AGE-specific cross-links within old muscle, and observed that old DMM retained AGE cross-links using ALT-711 to reduce AGE levels. In conclusion, deleterious age-dependent modifications to collagen are present in DMM from old muscle, implying that age matters when sourcing skeletal muscle extracellular matrix as a biomaterial.

In Vitro Measurements of Cellular Forces and their Importance in the Lung-From the Sub- to the Multicellular Scale

Throughout life, the body is subjected to various mechanical forces on the organ, tissue, and cellular level. Mechanical stimuli are essential for organ development and function. One organ whose function depends on the tightly connected interplay between mechanical cell properties, biochemical signaling, and external forces is the lung. However, altered mechanical properties or excessive mechanical forces can also drive the onset and progression of severe pulmonary diseases. Characterizing the mechanical properties and forces that affect cell and tissue function is therefore necessary for understanding physiological and pathophysiological mechanisms. In recent years, multiple methods have been developed for cellular force measurements at multiple length scales, from subcellular forces to measuring the collective behavior of heterogeneous cellular networks. In this short review, we give a brief overview of the mechanical forces at play on the cellular level in the lung. We then focus on the technological aspects of measuring cellular forces at many length scales. We describe tools with a subcellular resolution and elaborate measurement techniques for collective multicellular units. Many of the technologies described are by no means restricted to lung research and have already been applied successfully to cells from various other tissues. However, integrating the knowledge gained from these multi-scale measurements in a unifying framework is still a major future challenge.

Reversal of Insulin Resistance in Overweight and Obese Subjects by trans-Resveratrol and Hesperetin Combination-Link to Dysglycemia, Blood Pressure, Dyslipidemia, and Low-Grade Inflammation

The dietary supplement, trans-resveratrol and hesperetin combination (tRES-HESP), induces expression of glyoxalase 1, countering the accumulation of reactive dicarbonyl glycating agent, methylglyoxal (MG), in overweight and obese subjects. tRES-HESP produced reversal of insulin resistance, improving dysglycemia and low-grade inflammation in a randomized, double-blind, placebo-controlled crossover study. Herein, we report further analysis of study variables. MG metabolism-related variables correlated with BMI, dysglycemia, vascular inflammation, blood pressure, and dyslipidemia. With tRES-HESP treatment, plasma MG correlated negatively with endothelial independent arterial dilatation (r = -0.48, p < 0.05) and negatively with peripheral blood mononuclear cell (PBMC) quinone reductase activity (r = -0.68, p < 0.05)-a marker of the activation status of transcription factor Nrf2. For change from baseline of PBMC gene expression with tRES-HESP treatment, Glo1 expression correlated negatively with change in the oral glucose tolerance test area-under-the-curve plasma glucose (ΔAUGg) (r = -0.56, p < 0.05) and thioredoxin interacting protein (TXNIP) correlated positively with ΔAUGg (r = 0.59, p < 0.05). Tumor necrosis factor-α (TNFα) correlated positively with change in fasting plasma glucose (r = 0.70, p < 0.001) and negatively with change in insulin sensitivity (r = -0.68, p < 0.01). These correlations were not present with placebo. tRES-HESP decreased low-grade inflammation, characterized by decreased expression of CCL2, COX-2, IL-8, and RAGE. Changes in CCL2, IL-8, and RAGE were intercorrelated and all correlated positively with changes in MLXIP, MAFF, MAFG, NCF1, and FTH1, and negatively with changes in HMOX1 and TKT; changes in IL-8 also correlated positively with change in COX-2. Total urinary excretion of tRES and HESP metabolites were strongly correlated. These findings suggest tRES-HESP counters MG accumulation and protein glycation, decreasing activation of the unfolded protein response and expression of TXNIP and TNFα, producing reversal of insulin resistance. tRES-HESP is suitable for further evaluation for treatment of insulin resistance and related disorders.

Mathematical modeling of ventilator-induced lung inflammation

Despite the benefits of mechanical ventilators, prolonged or misuse of ventilators may lead to ventilation-associated/ventilation-induced lung injury (VILI). Lung insults, such as respiratory infections and lung injuries, can damage the pulmonary epithelium, with the most severe cases needing mechanical ventilation for effective breathing and survival. Damaged epithelial cells within the alveoli trigger a local immune response. A key immune cell is the macrophage, which can differentiate into a spectrum of phenotypes ranging from pro- to anti-inflammatory. To gain a greater understanding of the mechanisms of the immune response to VILI and post-ventilation outcomes, we developed a mathematical model of interactions between the immune system and site of damage while accounting for macrophage phenotype. Through Latin hypercube sampling we generated a collection of parameter sets that are associated with a numerical steady state. We then simulated ventilation-induced damage using these steady state values as the initial conditions in order to evaluate how baseline immune state and lung health affect outcomes. We used a variety of methods to analyze the resulting parameter sets, transients, and outcomes, including a random forest decision tree algorithm and parameter sensitivity with eFAST. Analysis shows that parameters and properties of transients related to epithelial repair and M1 activation are important factors. Using the results of this analysis, we hypothesized interventions and used these treatment strategies to modulate the response to ventilation for particular parameters sets.

Dicarbonyl stress, protein glycation and the unfolded protein response

The reactive dicarbonyl metabolite, methylglyoxal (MG), is increased in obesity and diabetes and is implicated in the development of insulin resistance, type 2 diabetes mellitus and vascular complications of diabetes. Dicarbonyl stress is the metabolic state of abnormal high MG concentration. MG is an arginine-directed glycating agent and precursor of the major advanced glycation endproduct, arginine-derived hydroimidazolone MG-H1. MG-H1 is often formed on protein surfaces and an uncharged hydrophobic residue, inducing protein structural distortion and misfolding. Recent studies indicate that dicarbonyl stress in human endothelial cells and fibroblasts in vitro induced a proteomic response consistent with activation of the unfolded protein response (UPR). The response included: increased abundance of heat shock proteins and ubiquitin ligases catalysing the removal of proteins with unshielded surface hydrophobic patches and formation of polyubiquitinated chains to encapsulate misfolded proteins; and increased low grade inflammation. Activation of the UPR is implicated in insulin resistance. An effective strategy to counter increased MG is inducing increased expression of glyoxalase-1 (Glo1). An optimized inducer of Glo1 expression, trans-resveratrol and hesperetin combination, normalized increased MG concentration, corrected insulin resistance and decreased low grade inflammation in overweight and obese subjects. We propose that dicarbonyl stress, through increased formation of MG-glycated proteins, may be an important physiological stimulus of the UPR and Glo1 inducers may provide a route to effective suppression and therapy. With further investigation and validation, this may provide key new insight into physiological activators of the UPR and association with dicarbonyl stress.

Nanoparticle delivery of microRNA-146a regulates mechanotransduction in lung macrophages and mitigates injury during mechanical ventilation

Mechanical ventilation generates injurious forces that exacerbate lung injury. These forces disrupt lung barrier integrity, trigger proinflammatory mediator release, and differentially regulate genes and non-coding oligonucleotides including microRNAs. In this study, we identify miR-146a as a mechanosensitive microRNA in alveolar macrophages that has therapeutic potential to mitigate lung injury during mechanical ventilation. We use humanized in-vitro systems, mouse models, and biospecimens from patients to elucidate the expression dynamics of miR-146a needed to decrease lung injury during mechanical ventilation. We find that the endogenous increase in miR-146a following injurious ventilation is not sufficient to prevent lung injury. However, when miR-146a is highly overexpressed using a nanoparticle delivery platform it is sufficient to prevent injury. These data indicate that the endogenous increase in microRNA-146a during mechanical ventilation is a compensatory response that partially limits injury and that nanoparticle delivery of miR-146a is an effective strategy for mitigating lung injury during mechanical ventilation.

Molecular Regulators of Cellular Mechanoadaptation at Cell-Material Interfaces

Diverse essential cellular behaviors are determined by extracellular physical cues that are detected by highly orchestrated subcellular interactions with the extracellular microenvironment. To maintain the reciprocity of cellular responses and mechanical properties of the extracellular matrix, cells utilize a variety of signaling pathways that transduce biophysical stimuli to biochemical reactions. Recent advances in the micromanipulation of individual cells have shown that cellular responses to distinct physical and chemical features of the material are fundamental determinants of cellular mechanosensation and mechanotransduction. In the process of outside-in signal transduction, transmembrane protein integrins facilitate the formation of focal adhesion protein clusters that are connected to the cytoskeletal architecture and anchor the cell to the substrate. The linkers of nucleoskeleton and cytoskeleton molecular complexes, collectively termed LINC, are critical signal transducers that relay biophysical signals between the extranuclear cytoplasmic region and intranuclear nucleoplasmic region. Mechanical signals that involve cytoskeletal remodeling ultimately propagate into the nuclear envelope comprising the nuclear lamina in assistance with various nuclear membrane proteins, where nuclear mechanics play a key role in the subsequent alteration of gene expression and epigenetic modification. These intracellular mechanical signaling cues adjust cellular behaviors directly associated with mechanohomeostasis. Diverse strategies to modulate cell-material interfaces, including alteration of surface rigidity, confinement of cell adhesive region, and changes in surface topology, have been proposed to identify cellular signal transduction at the cellular and subcellular levels. In this review, we will discuss how a diversity of alterations in the physical properties of materials induce distinct cellular responses such as adhesion, migration, proliferation, differentiation, and chromosomal organization. Furthermore, the pathological relevance of misregulated cellular mechanosensation and mechanotransduction in the progression of devastating human diseases, including cardiovascular diseases, cancer, and aging, will be extensively reviewed. Understanding cellular responses to various extracellular forces is expected to provide new insights into how cellular mechanoadaptation is modulated by manipulating the mechanics of extracellular matrix and the application of these materials in clinical aspects.

Alveolar cells under mechanical stressed niche: critical contributors to pulmonary fibrosis

Pulmonary fibrosis arises from the repeated epithelial mild injuries and insufficient repair lead to over activation of fibroblasts and excessive deposition of extracellular matrix, which result in a mechanical stretched niche. However, increasing mechanical stress likely exists before the establishment of fibrosis since early micro injuries increase local vascular permeability and prompt cytoskeletal remodeling which alter cellular mechanical forces. It is noteworthy that COVID-19 patients with severe hypoxemia will receive mechanical ventilation as supportive treatment and subsequent pathology studies indicate lung fibrosis pattern. At advanced stages, mechanical stress originates mainly from the stiff matrix since boundaries between stiff and compliant parts of the tissue could generate mechanical stress. Therefore, mechanical stress has a significant role in the whole development process of pulmonary fibrosis. The alveoli are covered by abundant capillaries and function as the main gas exchange unit. Constantly subject to variety of damages, the alveolar epithelium injuries were recently recognized to play a vital role in the onset and development of idiopathic pulmonary fibrosis. In this review, we summarize the literature regarding the effects of mechanical stress on the fundamental cells constituting the alveoli in the process of pulmonary fibrosis, particularly on epithelial cells, capillary endothelial cells, fibroblasts, mast cells, macrophages and stem cells. Finally, we briefly review this issue from a more comprehensive perspective: the metabolic and epigenetic regulation.

NEK7 mediated assembly and activation of NLRP3 inflammasome downstream of potassium efflux in ventilator-induced lung injury

Disordered immune regulation and persistent inflammatory damage are the key mechanisms of ventilator-induced lung injury (VILI). NLR family pyrin domain containing 3 (NLRP3) inflammasome activation causes VILI by mediating the formation of inflammatory mediators and infiltration of inflammatory cells, increasing pulmonary capillary membrane permeability, which leads to pulmonary edema and lung tissue damage. What mediates activation of NLRP3 inflammasome in VILI? In this study, we constructed an in vitro cyclic stretch (CS)-stimulated mouse lung epithelial (MLE-12) cell model that was transfected with NIMA-related kinase 7 (NEK7) small interfering RNA (siRNA) or scramble siRNA (sc siRNA) and pretreated with or without glibenclamide (glb). We also established a VILI mouse model, which was pretreated with glibenclamide or oridonin (Ori). Our goal was to investigate the regulatory effects of NEK7 on NLRP3 inflammasome activation and the anti-inflammatory effects of glibenclamide and oridonin on VILI. Mechanical stretch exaggerated the interaction between NEK7 and NLRP3, leading to assembly and activation of NLRP3 inflammasome downstream of potassium efflux. NEK7 depletion and treatment with glibenclamide or oridonin exerted anti-inflammatory effects that alleviated VILI by blocking the interaction between NEK7 and NLRP3, inhibiting NLRP3 inflammasome activation. NEK7 is a vital mediator of NLRP3 inflammasome activation, and glibenclamide or oridonin may be candidates for the development of new therapeutics against VILI driven by the interaction between NEK7 and NLRP3.

Mitofusin-2 regulates inflammation-mediated mouse neuroblastoma N2a cells dysfunction and endoplasmic reticulum stress via the Yap-Hippo pathway

Endoplasmic reticulum (ER) stress is involved in inflammation-induced neurotoxicity. Mitofusin 2 (Mfn2), a member of the GTPase family of proteins, resides in the ER membrane and is known to regulate ER stress. However, the potential role and underlying mechanism of Mfn2 in inflammation-induced neuronal dysfunction is unknown. In our study, we explored the potential of Mfn2 to attenuate inflammation-mediated neuronal dysfunction by inhibiting ER stress. Our data show that Mfn2 overexpression significantly ameliorated tumor necrosis factor alpha (TNFα)-induced ER stress, as indicated by the downregulation of the ER stress proteins PERK, GRP78 and CHOP. Mfn2 overexpression also prevented the TNFα-mediated activation of caspase-3, caspase-12 and cleaved poly (ADP-ribose) polymerase (PARP). Cellular antioxidant dysfunction and reactive oxygen species overproduction were also improved by Mfn2 in the setting of TNFα in mouse neuroblastoma N2a cells in vitro. Similarly, disordered calcium homeostasis, indicated by disturbed levels of calcium-related proteins and calcium overloading, was corrected by Mfn2, as evidenced by the increased expression of store-operated calcium entry (SERCA), decreased levels of inositol trisphosphate receptor (IP3R), and normalized calcium content in TNFα-treated N2a cells. Mfn2 overexpression was found to elevate Yes-associated protein (Yap) expression; knockdown of Yap abolished the regulatory effects of Mfn2 on ER stress, oxidative stress, calcium balance, neural death and inflammatory injury. These results lead us to conclude that re-activation of the Mfn2-Yap signaling pathway alleviates TNFα-induced ER stress and dysfunction of mouse neuroblastoma N2a cells. Our findings provide a better understanding of the regulatory role of Mfn2-Yap-ER stress in neuroinflammation and indicate that the Mfn2-Yap axis may be a focus of research in terms of having therapeutic value for the treatment of neurodegenerative diseases.

Effect of alcohol on the interleukin 6-mediated inflammatory response in a new mouse model of acute-on-chronic liver injury

BACKGROUND AND AIMS

ACLF is usually associated with a precipitant in the setting of a chronically damaged liver. We aim to combine a mouse model with a pre-injured liver (Abcb4/Mdr2^-/-) with a recently standardized ethanol feeding model to dissect alcohol-related inflammatory responses in this model.

METHOD

Ten (n = 64) and 15 (n = 64) week old wild-type (WT) C57BL/6 J and Abcb4^-/- knock-out (KO) mice were either fed control (WT/Cont and KO/Cont groups) or liquid ethanol diet (5% v/v) followed by an ethanol binge (4 mg/kg) (WT/EtOH and KO/EtOH groups). Hepatic mRNA levels of IL6, IFN-G, IL-1B, TGFB1, TNF-A, CCL2, HGF, CRP, RANTES, PNPLA3 and COL3A1 were evaluated using the 2^-ΔΔCt method. IL6 and HGF plasma levels were quantified by ELISA.

RESULTS

Older mice in KO/EtOH group displayed higher IL6 expressions compared to KO/Cont, WT/EtOH and WT/Cont groups of the same age, whereas HGF did not differ. Significant over-expression of CCL2 also corresponded to the same group. Males in KO/EtOH group exhibited higher IL6 expression than females. Lipid droplets were observed in about 80% of mice challenged with ethanol. There was a profound downregulation in PNPLA3 and RANTES levels after ethanol exposure. Mean size of the LDs was inversely correlated with hepatic PNPLA3 levels.

CONCLUSION

We propose a novel promising approach to model alcohol-related ACLI. Acute inflammatory IL6-driven response might help transition from a stable chronic state to a progressive liver damage in Abcb4^-/- mice. Repression of PNPLA3 resulted in a notable expansion in size of lipid droplets, indicating lipid remodeling in this model.