Cathepsin S deficiency results in abnormal accumulation of autophagosomes in macrophages and enhances Ang II-induced cardiac inflammation

Neutrophil-Derived Proteases in Lung Inflammation: Old Players and New Prospects

Neutrophil-derived proteases are critical to the pathology of many inflammatory lung diseases, both chronic and acute. These abundant enzymes play roles in key neutrophil functions, such as neutrophil extracellular trap formation and reactive oxygen species release. They may also be released, inducing tissue damage and loss of tissue function. Historically, the neutrophil serine proteases (NSPs) have been the main subject of neutrophil protease research. Despite highly promising cell-based and animal model work, clinical trials involving the inhibition of NSPs have shown mixed results in lung disease patients. As such, the cutting edge of neutrophil-derived protease research has shifted to proteases that have had little-to-no research in neutrophils to date. These include the cysteine and serine cathepsins, the metzincins and the calpains, among others. This review aims to outline the previous work carried out on NSPs, including the shortcomings of some of the inhibitor-orientated clinical trials. Our growing understanding of other proteases involved in neutrophil function and neutrophilic lung inflammation will then be discussed. Additionally, the potential of targeting these more obscure neutrophil proteases will be highlighted, as they may represent new targets for inhibitor-based treatments of neutrophil-mediated lung inflammation.

Comprehensive view of macrophage autophagy and its application in cardiovascular diseases

Cardiovascular diseases (CVDs) are the primary drivers of the growing public health epidemic and the leading cause of premature mortality and economic burden worldwide. With decades of research, CVDs have been proven to be associated with the dysregulation of the inflammatory response, with macrophages playing imperative roles in influencing the prognosis of CVDs. Autophagy is a conserved pathway that maintains cellular functions. Emerging evidence has revealed an intrinsic connection between autophagy and macrophage functions. This review focuses on the role and underlying mechanisms of autophagy-mediated regulation of macrophage plasticity in polarization, inflammasome activation, cytokine secretion, metabolism, phagocytosis, and the number of macrophages. In addition, autophagy has been shown to connect macrophages and heart cells. It is attributed to specific substrate degradation or signalling pathway activation by autophagy-related proteins. Referring to the latest reports, applications targeting macrophage autophagy have been discussed in CVDs, such as atherosclerosis, myocardial infarction, heart failure, and myocarditis. This review describes a novel approach for future CVD therapies.

Mitochondrial quality control in health and cardiovascular diseases

Cardiovascular diseases (CVDs) are one of the primary causes of mortality worldwide. An optimal mitochondrial function is central to supplying tissues with high energy demand, such as the cardiovascular system. In addition to producing ATP as a power source, mitochondria are also heavily involved in adaptation to environmental stress and fine-tuning tissue functions. Mitochondrial quality control (MQC) through fission, fusion, mitophagy, and biogenesis ensures the clearance of dysfunctional mitochondria and preserves mitochondrial homeostasis in cardiovascular tissues. Furthermore, mitochondria generate reactive oxygen species (ROS), which trigger the production of pro-inflammatory cytokines and regulate cell survival. Mitochondrial dysfunction has been implicated in multiple CVDs, including ischemia-reperfusion (I/R), atherosclerosis, heart failure, cardiac hypertrophy, hypertension, diabetic and genetic cardiomyopathies, and Kawasaki Disease (KD). Thus, MQC is pivotal in promoting cardiovascular health. Here, we outline the mechanisms of MQC and discuss the current literature on mitochondrial adaptation in CVDs.

The Lysosome in Malignant Melanoma: Biology, Function and Therapeutic Applications

Lysosomes are membrane-bound vesicles that play roles in the degradation and recycling of cellular waste and homeostasis maintenance within cells. False alterations of lysosomal functions can lead to broad detrimental effects and cause various diseases, including cancers. Cancer cells that are rapidly proliferative and invasive are highly dependent on effective lysosomal function. Malignant melanoma is the most lethal form of skin cancer, with high metastasis characteristics, drug resistance, and aggressiveness. It is critical to understand the role of lysosomes in melanoma pathogenesis in order to improve the outcomes of melanoma patients. In this mini-review, we compile our current knowledge of lysosomes' role in tumorigenesis, progression, therapy resistance, and the current treatment strategies related to lysosomes in melanoma.

Overexpression of cathepsin S exacerbates lupus pathogenesis through upregulation TLR7 and IFN-α in transgenic mice

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that affects multiple organs. Recent studies suggest relevance between cysteine protease cathepsin S (CTSS) expression and SLE. To investigate the mechanism of CTSS in SLE, CTSS-overexpressing transgenic (TG) mice were generated, and induced lupus-like symptoms. Eight months later, the TG mice spontaneously developed typical SLE symptoms regardless of the inducement. Furthermore, we observed increased toll-like receptor 7 (TLR7) expression with increased monocyte and neutrophil populations in the TG mice. In conclusion, overexpression of CTSS in mice influences TLR7 expression, autoantibodies and IFN-α, which leads to an autoimmune reaction and exacerbates lupus-like symptoms.

ALS-associated genes in SCA2 mouse spinal cord transcriptomes

The spinocerebellar ataxia type 2 (SCA2) gene ATXN2 has a prominent role in the pathogenesis and treatment of amyotrophic lateral sclerosis (ALS). In addition to cerebellar ataxia, motor neuron disease is often seen in SCA2, and ATXN2 CAG repeat expansions in the long normal range increase ALS risk. Also, lowering ATXN2 expression in TDP-43 ALS mice prolongs their survival. Here we investigated the ATXN2 relationship with motor neuron dysfunction in vivo by comparing spinal cord (SC) transcriptomes reported from TDP-43 and SOD1 ALS mice and ALS patients with those from SCA2 mice. SC transcriptomes were determined using an SCA2 bacterial artificial chromosome mouse model expressing polyglutamine expanded ATXN2. SCA2 cerebellar transcriptomes were also determined, and we also investigated the modification of gene expression following treatment of SCA2 mice with an antisense oligonucleotide (ASO) lowering ATXN2 expression. Differentially expressed genes (DEGs) defined three interconnected pathways (innate immunity, fatty acid biosynthesis and cholesterol biosynthesis) in separate modules identified by weighted gene co-expression network analysis. Other key pathways included the complement system and lysosome/phagosome pathways. Of all DEGs in SC, 12.6% were also dysregulated in the cerebellum. Treatment of mice with an ATXN2 ASO also modified innate immunity, the complement system and lysosome/phagosome pathways. This study provides new insights into the underlying molecular basis of SCA2 SC phenotypes and demonstrates annotated pathways shared with TDP-43 and SOD1 ALS mice and ALS patients. It also emphasizes the importance of ATXN2 in motor neuron degeneration and confirms ATXN2 as a therapeutic target.

Deficiency of peroxisome proliferator-activated receptor α attenuates apoptosis and promotes migration of vascular smooth muscle cells

Peroxisome proliferator-activated receptor (PPAR) α is widely expressed in the vasculature and has pleiotropic and lipid-lowering independent effects, but its role in the growth and function of vascular smooth muscle cells (VSMCs) during vascular pathophysiology is still unclear. Herein, VSMC-specific PPARα-deficient mice (Ppara ^ΔSMC) were generated by Cre-LoxP site-specific recombinase technology and VSMCs were isolated from mice aorta. PPARα deficiency attenuated VSMC apoptosis induced by angiotensin (Ang) II and hydrogen peroxide, and increased the migration of Ang II-challenged cells.

Transfer of exosomal microRNA-203-3p from dendritic cells to bone marrow-derived macrophages reduces development of atherosclerosis by downregulating Ctss in mice

Dendritic cell-derived exosomes have been proven to be efficient adjuvant options for anti-tumor vaccines in cancer immunotherapy. However, their potency in atherosclerosis remains unclear. Here we summarize the association of microRNA-203-3p (miR-203-3p) with dendritic cell-derived exosomes and atherosclerosis. Firstly, dendritic cell-derived exosomes and bone marrow-derived macrophages were isolated, after which expression of miR-203-3p and cathepsin S was determined. After the establishment of atherosclerosis mouse models, gain- and loss-of-function experiments were conducted for the analysis of effects of miR-203-3p and cathepsin S on foam-cell formation, lipid accumulation, collagen deposition and serum total cholesterol. The results found high expression of cathepsin S in atherosclerosis mice and downregulation of miR-203-3p in the serum of atherosclerosis patients and ox-LDL-simulated bone marrow-derived macrophages. Cathepsin S was the target gene of miR-203-3p. miR-203-3p transporting from exosomes to bone marrow-derived macrophages resulted in inhibition of cathepsin S expression and atherosclerosis-related phenotypes in bone marrow-derived macrophages, thus alleviating atherosclerosis in mice, and this process was found to involve the p38/MAPK signaling pathway. These findings provided evidence that the transfer of miR-203-3p by dendritic cell-derived exosomes targeted cathepsin S in bone marrow-derived macrophages to attenuate atherosclerosis progression in mice, serving as a promising clinical target for atherosclerosis.

Mitochondrial Morphology and Mitophagy in Heart Diseases: Qualitative and Quantitative Analyses Using Transmission Electron Microscopy

Transmission electron microscopy (TEM) has long been an important technique, capable of high degree resolution and visualization of subcellular structures and organization. Over the last 20 years, TEM has gained popularity in the cardiovascular field to visualize changes at the nanometer scale in cardiac ultrastructure during cardiovascular development, aging, and a broad range of pathologies. Recently, the cardiovascular TEM enabled the studying of several signaling processes impacting mitochondrial function, such as mitochondrial fission/fusion, autophagy, mitophagy, lysosomal degradation, and lipophagy. The goals of this review are to provide an overview of the current usage of TEM to study cardiac ultrastructural changes; to understand how TEM aided the visualization of mitochondria, autophagy, and mitophagy under normal and cardiovascular disease conditions; and to discuss the overall advantages and disadvantages of TEM and potential future capabilities and advancements in the field.

Quality Matters? The Involvement of Mitochondrial Quality Control in Cardiovascular Disease

Cardiovascular diseases are one of the leading causes of death and global health problems worldwide. Multiple factors are known to affect the cardiovascular system from lifestyles, genes, underlying comorbidities, and age. Requiring high workload, metabolism of the heart is largely dependent on continuous power supply via mitochondria through effective oxidative respiration. Mitochondria not only serve as cellular power plants, but are also involved in many critical cellular processes, including the generation of intracellular reactive oxygen species (ROS) and regulating cellular survival. To cope with environmental stress, mitochondrial function has been suggested to be essential during bioenergetics adaptation resulting in cardiac pathological remodeling. Thus, mitochondrial dysfunction has been advocated in various aspects of cardiovascular pathology including the response to ischemia/reperfusion (I/R) injury, hypertension (HTN), and cardiovascular complications related to type 2 diabetes mellitus (DM). Therefore, mitochondrial homeostasis through mitochondrial dynamics and quality control is pivotal in the maintenance of cardiac health. Impairment of the segregation of damaged components and degradation of unhealthy mitochondria through autophagic mechanisms may play a crucial role in the pathogenesis of various cardiac disorders. This article provides in-depth understanding of the current literature regarding mitochondrial remodeling and dynamics in cardiovascular diseases.

Dibenzazepine combats acute liver injury in rats via amendments of Notch signaling and activation of autophagy

Paracetamol is a commonly used over-the-counter analgesic and antipyretic drug. Nevertheless, an overdose of paracetamol leads to hepatic necrosis that can be lethal. This study aimed to assess the potential hepatoprotective effects of dibenzazepine, a Notch inhibitor, against acute liver injury in rats via interfering with oxidative stress, inflammation, apoptosis, autophagy, and Notch signaling. Silymarin (200 mg/kg, p.o.) or dibenzazepine (2 mg/kg, i.p.) were administered to rats for 5 days before a single hepatotoxic dose of paracetamol (800 mg/kg, i.p.). Pretreatment with silymarin and dibenzazepine significantly mitigated oxidative stress, inflammatory and apoptotic markers induced by paracetamol hepatotoxicity where dibenzazepine showed greater repression of inflammation. Furthermore, dibenzazepine was found to be significantly more efficacious than silymarin in inhibiting Notch signaling as represented by expression of Notch-1 and Hes-1. A significantly greater response was also demonstrated with dibenzazepine pretreatment with regard to the expression of autophagic proteins, Beclin-1 and LC-3. The aforementioned biochemical results were confirmed by histopathological examination. Autophagy and Notch signaling seem to play a significant role in protection provided by dibenzazepine for paracetamol-induced hepatotoxicity in rats, which could explain its superior results relative to silymarin. Graphical abstract.

Inhibition of Cathepsin S Induces Mitochondrial Apoptosis in Glioblastoma Cell Lines Through Mitochondrial Stress and Autophagosome Accumulation

Cathepsin S (CTSS), a lysosomal cysteine protease, is overexpressed in various cancers, including glioblastoma (GB). A high level of CTSS is associated with tumor progression and poor outcome in GB. However, the underlying mechanisms of its role in the biological characteristics of G5B remain to be elucidated. Here, we uncovered a potential role of CTSS in the lysosomes and mitochondria of GB cells (GBCs). Downregulation of CTSS in GBCs could increase the expression of autophagy-related proteins; however, there was no significant change in p62, suggesting autophagy blockade. Moreover, inhibition of CTSS increased the expression of mitochondrial calcium uniporter (MCU) and enhanced mitochondrial Ca²⁺ uptake ability, causing mitochondrial Ca²⁺ overload, the generation of copious reactive oxygen species (ROS) and eventual mitochondrial apoptosis. Additionally, elevated damage to mitochondria exacerbated the burden of autophagy. Finally, we found that silence of MCU could alleviate the inhibition of CTSS-induced autophagosome accumulation and mitochondrial stress. Collectively, these results demonstrate that CTSS plays an important role in the process of autophagic flux and mitochondrial functions in GBCs.

Dibenzazepine Attenuates Against Cisplatin-Induced Nephrotoxicity in Rats: Involvement of NOTCH Pathway

Cisplatin is one of the standard anti-cancer agents that are used to treat variety of solid tumors. Nevertheless, due to the accumulation of cisplatin in the renal epithelial cells, nephrotoxicity was found to be the main side effect that limits its clinical use. The current study was conducted to assess the potential nephroprotective effect of dibenzazepine, a Notch inhibitor, against cisplatin-induced nephrotoxicity in rats as well as the possible mechanisms underlying this nephroprotection. The rats were pre-treated with 2 mg/kg dibenzazepine for 7 days before giving a single nephrotoxic dose of cisplatin (7 mg/kg). Cisplatin induced acute nephrotoxicity, where blood urea nitrogen and serum creatinine levels were significantly increased. Besides, lipid peroxidation was markedly elevated and the levels of reduced glutathione and catalase were significantly reduced. Also, the tissue levels of the pro-inflammatory mediators; IL-1β, TNF-α, and NF-kB, were significantly increased in the cisplatin group. The pre-treatment with dibenzazepine significantly mitigated the nephrotoxic effects of cisplatin, the oxidative stress and inflammatory status as well as decreased caspase-3 expression, as compared to the cisplatin group. Furthermore, the up-regulation of Notch-1 and Hes-1 was found to be involved in cisplatin-induced nephrotoxicity and their expression was significantly reduced by dibenzazepine. The nephroprotective effect of dibenzazepine was further confirmed by the histopathological assessment. Moreover, dibenzazepine pre-treatment of hela and PC3 cells in vitro did not antagonize the cisplatin anti-cancer activity. In conclusion, these findings show that dibenzazepine provides protection against cisplatin-induced nephrotoxicity. Moreover, the up-regulation of the Notch pathway was shown to play a role in the pathogenesis of cisplatin-induced renal injury.

Cp1/cathepsin L is required for autolysosomal clearance in Drosophila

Macroautophagy/autophagy is a highly conserved lysosomal degradative pathway important for maintaining cellular homeostasis. Much of our current knowledge of autophagy is focused on the initiation steps in this process. Recently, an understanding of later steps, particularly lysosomal fusion leading to autolysosome formation and the subsequent role of lysosomal enzymes in degradation and recycling, is becoming evident. Autophagy can function in both cell survival and cell death, however, the mechanisms that distinguish adaptive/survival autophagy from autophagy-dependent cell death remain to be established. Here, using proteomic analysis of Drosophila larval midguts during degradation, we identify a group of proteins with peptidase activity, suggesting a role in autophagy-dependent cell death. We show that Cp1/cathepsin L-deficient larval midgut cells accumulate aberrant autophagic vesicles due to a block in autophagic flux, yet later stages of midgut degradation are not compromised. The accumulation of large aberrant autolysosomes in the absence of Cp1 appears to be the consequence of decreased degradative capacity as they contain undigested cytoplasmic material, rather than a defect in autophagosome-lysosome fusion. Finally, we find that other cathepsins may also contribute to proper autolysosomal degradation in Drosophila larval midgut cells. Our findings provide evidence that cathepsins play an essential role in the autolysosome to maintain basal autophagy flux by balancing autophagosome production and turnover.

Cathepsin A knockdown decreases the proliferation and invasion of A549 lung adenocarcinoma cells

Cathepsin A (CTSA) is a lysosomal protease that is abnormally expressed in various types of cancer; however, the function of CTSA in lung adenocarcinoma (LUAD) is unknown. The aim of the present study was to investigate the role of CTSA during LUAD development in vitro. The Cancer Genome Atlas (TCGA) database was used to analyze the expression of CTSA mRNA in LUAD tissues. CTSA was significantly upregulated in LUAD tissues compared with normal lung tissues. To explore the effect of CTSA on LUAD in vitro, LUAD A549 cells were transfected with CTSA small interfering RNA and the hallmarks of tumorigenesis were investigated using cell proliferation, cell cycle, wound healing, invasion and western blot assays. Following CTSA knockdown, proliferation of LUAD cells was decreased and an increased proportion of LUAD cells were arrested at the G₀/G₁ phase, with altered expression of critical cell cycle and proliferative marker proteins, including p53, p21 and proliferating cell nuclear antigen. Moreover, CTSA knockdown decreased the migration and invasion of A549 cells, as determined by wound healing, invasion, and western blotting assays. The expression levels of key proteins involved in epithelial-mesenchymal transition were analyzed by western blotting. CTSA knockdown enhanced the expression of E-cadherin, but decreased the expression of N-cadherin and β-catenin in A549 cells. To the best of our knowledge, the present study suggested for the first time it has been identified that CTSA may serve as a tumor promoter in LUAD, enhancing the malignant progression of LUAD cells by promoting cell proliferation, migration and invasion. The results suggested that CTSA may serve as a novel therapeutic target for LUAD.

Cysteinyl cathepsins in cardiovascular diseases

Cysteinyl cathepsins are lysosomal/endosomal proteases that mediate bulk protein degradation in these intracellular acidic compartments. Yet, studies indicate that these proteases also appear in the nucleus, nuclear membrane, cytosol, plasma membrane, and extracellular space. Patients with cardiovascular diseases (CVD) show increased levels of cathepsins in the heart, aorta, and plasma. Plasma cathepsins often serve as biomarkers or risk factors of CVD. In aortic diseases, such as atherosclerosis and abdominal aneurysms, cathepsins play pathogenic roles, but many of the same cathepsins are cardioprotective in hypertensive, hypertrophic, and infarcted hearts. During the development of CVD, cathepsins are regulated by inflammatory cytokines, growth factors, hypertensive stimuli, oxidative stress, and many others. Cathepsin activities in inflammatory molecule activation, immunity, cell migration, cholesterol metabolism, neovascularization, cell death, cell signaling, and tissue fibrosis all contribute to CVD and are reviewed in this article in memory of Dr. Nobuhiko Katunuma for his contribution to the field.

Autophagy in Neurotrauma: Good, Bad, or Dysregulated

Autophagy is a physiological process that helps maintain a balance between the manufacture of cellular components and breakdown of damaged organelles and other toxic cellular constituents. Changes in autophagic markers are readily detectable in the spinal cord and brain following neurotrauma, including traumatic spinal cord and brain injury (SCI/TBI). However, the role of autophagy in neurotrauma remains less clear. Whether autophagy is good or bad is under debate, with strong support for both a beneficial and detrimental role for autophagy in experimental models of neurotrauma. Emerging data suggest that autophagic flux, a measure of autophagic degradation activity, is impaired in injured central nervous systems (CNS), and interventions that stimulate autophagic flux may provide neuroprotection in SCI/TBI models. Recent data demonstrating that neurotrauma can cause lysosomal membrane damage resulting in pathological autophagosome accumulation in the spinal cord and brain further supports the idea that the impairment of the autophagy-lysosome pathway may be a part of secondary injury processes of SCI/TBI. Here, we review experimental work on the complex and varied responses of autophagy in terms of both the beneficial and detrimental effects in SCI and TBI models. We also discuss the existing and developing therapeutic options aimed at reducing the disruption of autophagy to protect the CNS after injuries.

Identification and characterization of the lamprey cathepsin genes

Cathepsins are key mammalian proteases that play an important role in the immune response. Several studies have revealed the versatile and critical functions of cathepsins. Here, we obtained ten kinds of cathepsin homologs and identified seven homologs with complete coding sequences. Phylogenetic analysis verified their identities and supported the classification of cathepsins into seven families, which is similar to other vertebrates. Tissue-specific expression analysis showed that all lamprey cathepsins (L-cathepsins) are present in the supraneural body (SB), kidney, gill, intestine, brain, heart, and liver, but their relative abundance varied among tissues. Additionally, we focused on the lamprey cathepsin L (L-cathepsin L) and used recombinant L-cathepsin L protein (rL-cathepsin L) to prepare anti rL-cathepsin L polyclonal antibodies, which were used to detect its distribution in lamprey tissues. The L-cathepsin L protein was primarily detected in the SB, kidney, gill, intestine, brain, and liver via western blot and immunohistochemistry assays. Importantly, quantitative real-time PCR (RT-PCR) revealed that the expression level of L-cathepsins mRNA significantly increased after exposure to three different stimuli (poly I:C, Staphylococcus aureus (S.a) and Vibro anguilarum (V.an)). This suggested that L-cathepsins may participate in defense processes. These results revealed that L-cathepsins may play key roles in the immune response to exogenous stimuli. The findings provide important information for future studies aiming to understand the molecular mechanisms underlying the immune response to pathogen invasion in lamprey.

Advanced glycation end products-related modulation of cathepsin L and NF-κB signalling effectors in retinal pigment epithelium lead to augmented response to TNFα

The retinal pigment epithelium (RPE) plays a central role in neuroretinal homoeostasis throughout life. Altered proteolysis and inflammatory processes involving RPE contribute to the pathophysiology of age‐related macular degeneration (AMD), but the link between these remains elusive. We report for the first time the effect of advanced glycation end products (AGE)—known to accumulate on the ageing RPE's underlying Bruch's membrane in situ—on both key lysosomal cathepsins and NF‐κB signalling in RPE. Cathepsin L activity and NF‐κB effector levels decreased significantly following 2‐week AGE exposure. Chemical cathepsin L inhibition also decreased total p65 protein levels, indicating that AGE‐related change of NF‐κB effectors in RPE cells may be modulated by cathepsin L. However, upon TNFα stimulation, AGE‐exposed cells had significantly higher ratio of phospho‐p65(Ser536)/total p65 compared to non‐AGEd controls, with an even higher fold increase than in the presence of cathepsin L inhibition alone. Increased proportion of active p65 indicates an AGE‐related activation of NF‐κB signalling in a higher proportion of cells and/or an enhanced response to TNFα. Thus, NF‐κB signalling modulation in the AGEd environment, partially regulated via cathepsin L, is employed by RPE cells as a protective (para‐inflammatory) mechanism but renders them more responsive to pro‐inflammatory stimuli.

Z-FL-COCHO, a cathepsin S inhibitor, enhances oxaliplatin-mediated apoptosis through the induction of endoplasmic reticulum stress

Multiple cancer cells highly express cathepsin S, which has pro-tumoral effects. However, it was previously unknown whether knockdown or a pharmacological inhibitor (ZFL) of cathepsin S acts as an inducer of ER stress. Here, ZFL and knockdown of cathepsin S markedly induced ER stress through the up-regulation of calcium levels in the cytosol. Induction of calcium levels by inhibition of cathepsin S is markedly blocked by an inhibitor of the IP3 receptor and the ryanodine receptor Ca²⁺ channel in the ER, but an inhibitor of a mitochondrial Ca²⁺ uniporter had no effect on ZFL-induced calcium levels. Furthermore, production of mitochondrial ROS by ZFL was associated with an increase in cytosolic calcium levels. ZFL-mediated ER stress enhanced anti-cancer drug-induced apoptotic cell death, and pretreatment with chemical chaperones or down-regulation of ATF4 and CHOP by small interfering RNA markedly reduced ZFL plus oxaliplatin-induced apoptosis. Taken together, our findings reveal that inhibition of cathepsin S is an inducer of ER stress; these findings may contribute to the enhancement of therapeutic efficiency in cancer cells.

A drug that inhibits a key cancer enzyme could be used in combination with anti-cancer drugs to improve sensitivity to treatment. The intracellular endoplasmic reticulum (ER) is involved in several vital processes in cells, including folding and processing proteins. Taeg Kyu Kwon at Keimyung University, Daegu, South Korea, and co-workers have demonstrated how inhibition of cathepsin S, which is expressed in many cancer cells, induces ER stress. In trials on human kidney cancer cells grafted onto mice and in vitro, the team found that ZFL (cathepsin S inhibitor) triggered transient ER stress by increasing calcium levels inside cells. Subsequent treatment with the anti-cancer drug oxaliplatin resulted in increased cancer cell death.

Integrated bioinformatics analysis reveals that the expression of cathepsin S is associated with lymph node metastasis and poor prognosis in papillary thyroid cancer

The prognosis of the majority of patients with papillary thyroid cancer (PTC) is excellent, although there are patients who experience disease recurrence and progression. The aim of the present study was to identify potential prognostic risk markers in PTC. Differentially expressed genes (DEGs), identified from four Genome Expression Omnibus cohorts were subjected to functional enrichment analyses with Gene Ontology terms and the Kyoto Encyclopedia of Genes and Genome pathways. Hub genes, filtered from cytoHubba, were validated using the The Cancer Genome Atlas (TCGA) cohort, and their associations with clinicopathological features and prognosis were analyzed. A total of 277 DEGs were identified following data preprocessing. DEGs were primarily enriched in 'small cell lung cancer', 'ECM-receptor interaction', 'pathways in cancer'and 'tyrosine metabolism'. Hub genes [APOE, cathepsin S (CTSS), insulin receptor substrate 1 (IRS1), KIT, LGALS3, RUNX2 and TGFBR1] were extracted from cytoHubba. Their expression in the TCGA cohort was consistent with that in the GEO cohorts. CTSS (P=0.006) and IRS1 (P=0.005) were associated with disease‑free survival, as determined using the Kaplan-Meier analysis. CTSS was an independent risk factor for poor disease‑free survival (HR, 2.649; 95% CI, 1.095-6.409; P=0.031). Patients with high expression of CTSS exhibited different histological types (increased tall-cell subtype and reduced follicular subtype; P<0.001), more frequent lymph node metastasis (P<0.001) and advanced tumor-node-metastasis stages (P=0.049) compared with the low-expression group. High expression of CTSS was independently associated with lymph node metastasis (OR, 2.015; 95% CI, 1.225-3.315; P=0.006). Therefore, CTSS may serve as a predictive risk marker for the progression and prognosis of PTC.

Increased plasma cathepsin S and trombospondin-1 in patients with acute ST-segment elevation myocardial infarction

BACKGROUND

The role of cathepsins in the pathological progression of atherosclerotic lesions in ischem-ic heart disease have been defined in detail more than numerous times. This investigation examined the platelet-specific biomarker trombospondin-1 (TSP-1) and platelet function ex vivo, and compared this with cathepsin S (Cat-S; a biomarker unrelated to platelet activation but also associated this with increased mortality risk) in patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

The STEMI patients were divided into two groups depending on the degree of coronary vessel occlusion: those with closed (n = 90) and open culprit vessel (n = 40). Cat-S and TSP-1 were analyzed before, 1-3 days after and 3 months after percutanous coronary intervention (PCI).

RESULTS

During acute STEMI, plasma TSP-1 was significantly elevated in patients with closed cul-prit lesions, but rapidly declined after PCI. In fact, TSP-1 after PCI was significantly lower inpatient samples compared to healthy individuals. In comparison, plasma Cat-S was significantly elevated both before and after PCI. In patients with closed culprit lesions, Cat-S was significantly higher compared to patients with open culprit lesions 3 months after PCI. Although troponin-I were higher (p < 0.01) in patients with closed culprit lesion, there was no correlation with Cat-S and TSP-1.

CONCLUSIONS

Cat-S but not TSP-1 may be a useful risk biomarker in relation to the severity of STEMI. However, the causality of Cat-S as a predictor for long-term mortality in STEMI remains to be ascertained in future studies.

Evaluating the diagnostic and prognostic value of circulating cathepsin S in gastric cancer

To evaluate whether serum Cathepsin S (Cat S) could serve as a biomarker for the diagnosis and prognosis of gastric cancer (GC), Enzyme-linked immuno sorbent assay (ELISA) was used to detect serum Cat S in 496 participants including healthy controls and patients with benign gastric diseases, gastric cancer, esophageal cancer, liver cancer, colorectal cancer, nasopharyngeal cancer and lung cancer. The levels of serum Cat S were significantly increased in cancer patients, especially in GC patients. The qRT-PCR, Western blotting, and immunohistochemical staining revealed the overexpression of Cat S in GC cell lines and tissues. The diagnostic value of serum Cat S for GC patients from controls resulted in an AUC of 0.803 with a sensitivity of 60.7% and a specificity of 90.0%. Moreover, the levels of serum Cat S were associated with GC tumor volume, lymphoid nodal status, metastasis status, and stages. Moreover, the patients with high levels of serum Cat S had a poorer overall survival. Univariate analysis revealed Cat S expression was a prognostic factor. The knockdown of Cat S significantly suppressed the migration and invasion of GC cells. This study suggested serum Cat S may be a potential biomarker for the diagnosis and prognosis of GC.

Influence of lipopolysaccharides on autophagy and inflammation in pancreatic islet cells of mice fed by high-fat diet

The aim of this study was to confirm whether chronic low-grade inflammation could induce autophagy and damage in islet cells. The high-fat diet (HF) and low-dose lipopolysaccharides (LPS) were used to simulate chronic inflammation. Islet function was observed, the expression of autophagy-related proteins and the activity of glucose synthase kinase 3β (GSK-3β) were detected, and the role of autophagy in islet injury induced by inflammation was explored. Higher blood glucose was observed in HF group and LPS group compared with control (C) group, and there was no significant difference between LPS group and LiCl group. The apoptotic pancreatic islet cells in the LPS group were higher than in the HF and C groups, and the in the LiCl group they were higher than in the C group and lower than in the LPS group. Compared with the C group, LC3II/I ratio in the HF group was increased ( P < 0.05), in LPS and LiCl groups it was lower than in the HF group, and in LiCl group it was higher than in the LPS group. There was no significant difference between HF group and C group with regard to the ratio of p-GSK-3β/GSK-3β, but in the LiCl group it was higher than in the LPS group. The results demonstrated that low-grade inflammation might cause autophagy flux impaired through activation of GSK-3β, and induced islet cells damage. LiCl could play a role in protecting islet cells through autophagy enhancement.

Mycobacterium tuberculosis Modulates miR-106b-5p to Control Cathepsin S Expression Resulting in Higher Pathogen Survival and Poor T-Cell Activation

The success of tuberculosis (TB) bacillus, Mycobacterium tuberculosis (Mtb), relies on the ability to survive in host cells and escape to immune surveillance and activation. We recently demonstrated that Mtb manipulation of host lysosomal cathepsins in macrophages leads to decreased enzymatic activity and pathogen survival. In addition, while searching for microRNAs (miRNAs) involved in posttranscriptional gene regulation during mycobacteria infection of human macrophages, we found that selected miRNAs such as miR-106b-5p were specifically upregulated by pathogenic mycobacteria. Here, we show that miR-106b-5p is actively manipulated by Mtb to ensure its survival in macrophages. Using an in silico prediction approach, we identified miR-106b-5p with a potential binding to the 3'-untranslated region of cathepsin S (CtsS) mRNA. We demonstrated by luminescence-based methods that miR-106b-5p indeed targets CTSS mRNA resulting in protein translation silencing. Moreover, miR-106b-5p gain-of-function experiments lead to a decreased CtsS expression favoring Mtb intracellular survival. By contrast, miR-106b-5p loss-of-function in infected cells was concomitant with increased CtsS expression, with significant intracellular killing of Mtb and T-cell activation. Modulation of miR-106b-5p did not impact necrosis, apoptosis or autophagy arguing that miR-106b-5p directly targeted CtsS expression as a way for Mtb to avoid exposure to degradative enzymes in the endocytic pathway. Altogether, our data suggest that manipulation of miR-106b-5p as a potential target for host-directed therapy for Mtb infection.

iTRAQ analysis of a mouse acute myocardial infarction model reveals that vitamin D binding protein promotes cardiomyocyte apoptosis after hypoxia

The proteome profile changes after acute myocardial infarction (AMI) and the roles played by important protein species remain poorly understood. Here, we constructed a mouse AMI model by ligating the left coronary artery of male C57B/6J mice to investigate the molecular changes after AMI on the protein level. Total proteins of the left ventricle were extracted and quantitatively analyzed by isobaric tags using relative and absolute quantitation (iTRAQ) technologies. The transcript and protein levels of important genes were further validated using quantitative polymerase chain reaction and western blot. An oxygen and glucose deprivation/reperfusion cell model was constructed using H9C2 cells to further validate the expression patterns and functions of important proteins after hypoxia. Seven hundred seventy-six proteins were identified as differentially abundant proteins after AMI, of which 406 were accumulated, and 370 were reduced. Gene ontology enrichment analysis showed that the most enriched molecular function category terms were binding, including calcium ion biding, GTP binding, actin binding and lipid binding. The expression levels of vitamin D binding protein (VDBP) and its related proteins were increased in both left ventricular tissue and H9C2 cells after ischemia-hypoxia. Overexpression of VDBP in H9C2 cells reduced vitamin D receptor and promoted the cell apoptosis rate after hypoxia. Our data provided new insights into proteome profile changes after AMI and indicated that VDBP could promote cardiomyocyte apoptosis after hypoxia.

Cathepsin S inhibition suppresses autoimmune-triggered inflammatory responses in macrophages

In several types of antigen-presenting cells (APCs), Cathepsin S (CatS) plays a crucial role in the regulation of MHC class II surface expression and consequently influences antigen (Ag) presentation of APCs to CD4⁺ T cells. During the assembly of MHC class II-Ag peptide complexes, CatS cleaves the invariant chain p10 (Lip10) - a fragment of the MHC class II-associated invariant chain peptide. In this report, we used a selective, high-affinity CatS inhibitor to suppress the proteolytic activity of CatS in lymphoid and myeloid cells. CatS inhibition resulted in a concentration-dependent Lip10 accumulation in B cells from both healthy donors and patients with systemic lupus erythematosus (SLE). Furthermore, CatS inhibition led to a decreased MHC class II expression on B cells, monocytes, and proinflammatory macrophages. In SLE patient-derived peripheral blood mononuclear cells, CatS inhibition led to a suppressed secretion of IL-6, TNFα, and IL-10. In a second step, we tested the effect of CatS inhibition on macrophages being exposed to patient-derived autoantibodies against C1q (anti-C1q) that are known to be associated with severe lupus nephritis. As shown previously, those SLE patient-derived high-affinity anti-C1q bound to immobilized C1q induce a proinflammatory phenotype in macrophages. Using this human in vitro model of autoimmunity, we found that CatS inhibition reduces the inflammatory responses of macrophages as demonstrated by a decreased secretion of proinflammatory cytokines, the downregulation of MHC class II and CD80. In summary, we can show that the used CatS inhibitor is able to block Lip10 degradation in healthy donor- and SLE patient-derived B cells and inhibits the induction of proinflammatory macrophages. Thus, CatS inhibition seems to be a promising future treatment of SLE.

Inhibition of Cathepsin S Induces Mitochondrial ROS That Sensitizes TRAIL-Mediated Apoptosis Through p53-Mediated Downregulation of Bcl-2 and c-FLIP

AIMS

Cathepsin S is highly expressed in various cancer cells, and it has protumoral effects, including promotion of migration, invasion, and neovascularization. In this study, we show that inhibition of cathepsin S could sensitize cancer cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis.

RESULTS

An inhibitor of cathepsin S (Z-FL-COCHO; ZFL) markedly induced apoptosis in human renal cancer cells treated with TRAIL. In contrast, combined treatment with ZFL and TRAIL had no effect on normal cells. ZFL downregulated Bcl-2 expression at the transcriptional level in a p53-dependent manner, and overexpression of Bcl-2 also markedly blocked apoptosis induced by combined treatment with ZFL and TRAIL. In addition, ZFL induced downregulation of c-FLIP, and overexpression of c-FLIP blocked the apoptosis induced by ZFL plus TRAIL. Moreover, ZFL increased the expression of Cbl, an E3 ligase of c-FLIP, in a p53-dependent manner, and knockdown of Cbl markedly prevented c-FLIP downregulation and the apoptosis induced by ZFL plus TRAIL. Interestingly, ZFL induced p53 expression via production of mitochondrial reactive oxygen species (ROS). We also demonstrated that downregulation of cathepsin S by small interfering RNA sensitized TRAIL-mediated apoptosis in Caki cells.

INNOVATION

These results reveal the importance of cathepsin S on resistance against TRAIL, and inhibition of cathepsin S activity plays a crucial role in TRAIL-mediated cell death of cancer cells.

CONCLUSION

Our results indicated that inhibition of cathepsin S stimulates TRAIL-induced apoptosis through downregulation of Bcl-2 and Cbl-mediated c-FLIP by ROS-mediated p53 expression. Antioxid. Redox Signal. 27, 215-233.

Proteases Revisited: Roles and Therapeutic Implications in Fibrosis

Proteases target many substrates, triggering changes in distinct biological processes correlated with cell migration, EMT/EndMT and fibrosis. Extracellular protease activity, demonstrated by secreted and membrane-bound protease forms, leads to ECM degradation, activation of other proteases (i.e., proteolysis of nonactive zymogens), decomposition of cell-cell junctions, release of sequestered growth factors (TGF-β and VEGF), activation of signal proteins and receptors, degradation of inflammatory inhibitors or inflammation-related proteins, and changes in cell mechanosensing and motility. Intracellular proteases, mainly caspases and cathepsins, modulate lysosome activity and signal transduction pathways. Herein, we discuss the current knowledge on the multidimensional impact of proteases on the development of fibrosis.

Inhibition of cathepsin S confers sensitivity to methyl protodioscin in oral cancer cells via activation of p38 MAPK/JNK signaling pathways

Oral cancer is one of the most common cancers in the world. Approximately 90% of oral cancers are subtyped to oral squamous cell carcinoma (OSCC). Despite advances in diagnostic techniques and improvement in treatment modalities, the prognosis remains poor. Therefore, an effective chemotherapy mechanism that enhances tumor sensitivity to chemotherapeutics is urgently needed. Methyl protodioscin (MP) is a furostanol bisglycoside with a wide range of beneficial effects, including anti-inflammatory and anti-cancer properties. The aim of the present study was to determine the antitumor activity of MP on OSCC and its underlying mechanisms. Our results show that treatment of OSCC cells with MP potently inhibited cell viability. Moreover, MP leading to cell cycle arrest at G2/M phase, which subsequently activates caspase-3, -8, -9 and PARP to induce cell apoptosis. Meanwhile, we also demonstrate that MP induces a robust autophagy in OSCC cells. The results indicate cathepsin S (CTSS) is involved in MP-induced apoptosis and autophagy by modulation of p38 MAPK and JNK1/2 pathways. These findings may provide rationale to combine MP with CTSS blockade for the effective treatment of OSCC.

Cysteine proteases in atherosclerosis

Atherosclerosis predisposes patients to cardiovascular diseases, such as myocardial infarction and stroke. Instigation of vascular injury is triggered by retention of lipids and inflammatory cells in the vascular endothelium. Whereas these vascular lesions develop in young adults and are mostly considered harmless, over time persistent inflammatory and remodeling processes will ultimately damage the arterial wall and cause a thrombotic event due to exposure of tissue factors into the lumen. Evidence from human tissues and preclinical animal models has clearly established the role of cathepsin cysteine proteases in the development and progression of vascular lesions. Hence, understanding the function of cathepsins in atherosclerosis is important for developing novel therapeutic strategies and advanced point of care diagnostics. In this review we will describe the roles of cysteine cathepsins in different cellular process that become dysfunctional in atherosclerosis, such as lipid metabolism, inflammation and apoptosis, and how they contribute to arterial remodeling and atherogenesis. Finally, we will explore new horizons in protease molecular imaging, which may potentially become a surrogate marker to identify future cardiovascular events.

The putative role of autophagy in the pathogenesis of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAA) are a significant cause of worldwide mortality and morbidity. While the histopathological characteristics of AAA are well documented, the cellular and molecular mechanisms involved in the pathogenesis of AAA are not entirely understood. Autophagy is a highly conserved basal cellular process in eukaryotic cells that involves the turnover of organelles and proteins. It is also activated as an adaptive response to stressful conditions to promote cell survival. While autophagy typically promotes pro-survival processes, it can sometimes lead to cellular demise. Preclinical studies have revealed autophagy to be a protective mechanism in certain vascular diseases with several autophagy-related genes reported to be markedly upregulated in human aneurysmal tissue. The role autophagy plays in the pathogenesis of AAA, however, remains poorly defined. In this review, we discuss the putative role of autophagy in AAA by reviewing several in vitro and in vivo studies that address the functional significance of autophagy in cells that are involved in the pathophysiology of AAA, amongst which are macrophages, smooth muscle and endothelial cells.

Six-SOMAmer Index Relating to Immune, Protease and Angiogenic Functions Predicts Progression in IPF

RATIONALE

Biomarkers in easily accessible compartments like peripheral blood that can predict disease progression in idiopathic pulmonary fibrosis (IPF) would be clinically useful regarding clinical trial participation or treatment decisions for patients. In this study, we used unbiased proteomics to identify relevant disease progression biomarkers in IPF.

METHODS

Plasma from IPF patients was measured using an 1129 analyte slow off-rate modified aptamer (SOMAmer) array, and patient outcomes were followed over the next 80 weeks. Receiver operating characteristic (ROC) curves evaluated sensitivity and specificity for levels of each biomarker and estimated area under the curve (AUC) when prognostic biomarker thresholds were used to predict disease progression. Both logistic and Cox regression models advised biomarker selection for a composite disease progression index; index biomarkers were weighted via expected progression-free days lost during follow-up with a biomarker on the unfavorable side of the threshold.

RESULTS

A six-analyte index, scaled 0 to 11, composed of markers of immune function, proteolysis and angiogenesis [high levels of ficolin-2 (FCN2), cathepsin-S (Cath-S), legumain (LGMN) and soluble vascular endothelial growth factor receptor 2 (VEGFsR2), but low levels of inducible T cell costimulator (ICOS) or trypsin 3 (TRY3)] predicted better progression-free survival in IPF with a ROC AUC of 0.91. An index score ≥ 3 (group ≥ 2) was strongly associated with IPF progression after adjustment for age, gender, smoking status, immunomodulation, forced vital capacity % predicted and diffusing capacity for carbon monoxide % predicted (HR 16.8, 95% CI 2.2-126.7, P = 0.006).

CONCLUSION

This index, derived from the largest proteomic analysis of IPF plasma samples to date, could be useful for clinical decision making in IPF, and the identified analytes suggest biological processes that may promote disease progression.

Influences of innate immunity, autophagy, and fibroblast activation in the pathogenesis of lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease characterized by accumulation of extracellular matrix (ECM) and impaired gas exchange. The pathobiological mechanisms that account for disease progression are poorly understood but likely involve alterations in innate inflammatory cells, epithelial cells, and fibroblasts. Thus we seek to review the most recent literature highlighting the complex roles of neutrophils and macrophages as both promoters of fibrosis and defenders against infection. With respect to epithelial cells and fibroblasts, we review the data suggesting that defective autophagy promotes the fibrogenic potential of both cell types and discuss new evidence related to matrix metalloproteinases, growth factors, and cellular metabolism in the form of lactic acid generation that may have consequences for promoting fibrogenesis. We discuss potential cross talk between innate and structural cell types and also highlight literature that may help explain the limitations of current IPF therapies.

P‑selectin increases angiotensin II‑induced cardiac inflammation and fibrosis via platelet activation

Platelet activation is important in hypertension-induced cardiac inflammation and fibrosis. P-selectin expression significantly (P<0.05) increases when platelets are activated during hypertension. Although P-selectin recruits leukocytes to sites of inflammation, the role of P-selectin in cardiac inflammation and fibrosis remains to be elucidated. The present study aimed to investigate whether platelet-derived P-selectin promotes hypertensive cardiac inflammation and fibrosis. P-selectin knockout (P-sel KO) mice and wild-type (WT) C57BL/6 littermates were infused with angiotensin II (Ang II) at 1,500 ng/kg/min for 7 days and then cross-transplanted with platelets originating from either WT or P-sel KO mice. P-selectin expression was increased in the myocardium and plasma of hypertensive mice, and the P-sel KO mice exhibited significantly (P<0.05) reduced cardiac fibrosis. The fibrotic areas were markedly smaller in the hearts of P-sel KO mice compared with WT mice, as assessed by Masson's trichrome staining. In addition, α-smooth muscle actin and transforming growth factor β1 (TGF-β1) expression levels were decreased in the P-sel KO mice, as assessed by immunohistochemistry. Following platelet transplantation into P-sel KO mice, the number of Mac-2 (galectin-3)- and TGF-β1-positive cells was increased in mice that received WT platelets compared with those that received P-sel KO platelets, and the mRNA expression levels of collagen I and TGF-β1 were also increased. The results from the present study suggest that activated platelets secrete P-selectin to promote cardiac inflammation and fibrosis in Ang II-induced hypertension.

Mycobacterium bovis BCG Interferes with miR-3619-5p Control of Cathepsin S in the Process of Autophagy

Main survival mechanism of pathogenic mycobacteria is to escape inimical phagolysosomal environment inside the macrophages. Many efforts have been made to unravel the molecular mechanisms behind this process. However, little is known about the involvement of microRNAs (miRNAs) in the regulation of phagolysosomal biosynthesis and maturation. Based on a bottom up approach, we searched for miRNAs that were involved in phagolysosomal processing events in the course of mycobacterial infection of macrophages. After infecting THP-1 derived macrophages with viable and heat killed Mycobacterium bovis BCG (BCG), early time points were identified after co-localization studies of the phagosomal marker protein LAMP1 and BCG. Differences in LAMP1 localization on the phagosomes of both groups were observed at 30 min and 4 h. After in silico based pre-selection of miRNAs, expression analysis at the identified time points revealed down-regulation of three miRNAs: miR-3619-5p, miR-637, and miR-324-3p. Consequently, most likely targets were predicted that were supposed to be mutually regulated by these three studied miRNAs. The lysosomal cysteine protease Cathepsin S (CTSS) and Rab11 family-interacting protein 4 (RAB11FIP4) were up-regulated and were considered to be connected to lysosomal trafficking and autophagy. Interaction studies verified the regulation of CTSS by miR-3619-5p. Down-regulation of CTSS by ectopic miR-3619-5p as well as its specific knockdown by siRNA affected the process of autophagy in THP-1 derived macrophages.

Cysteine cathepsin proteases: regulators of cancer progression and therapeutic response

Cysteine cathepsin protease activity is frequently dysregulated in the context of neoplastic transformation. Increased activity and aberrant localization of proteases within the tumour microenvironment have a potent role in driving cancer progression, proliferation, invasion and metastasis. Recent studies have also uncovered functions for cathepsins in the suppression of the response to therapeutic intervention in various malignancies. However, cathepsins can be either tumour promoting or tumour suppressive depending on the context, which emphasizes the importance of rigorous in vivo analyses to ascertain function. Here, we review the basic research and clinical findings that underlie the roles of cathepsins in cancer, and provide a roadmap for the rational integration of cathepsin-targeting agents into clinical treatment.

Inflammatory Stress on Autophagy in Peripheral Blood Mononuclear Cells from Patients with Alzheimer's Disease during 24 Months of Follow-Up

Recent findings indicate that microglia in Alzheimer's disease (AD) is senescent whereas peripheral blood mononuclear cells (PBMCs) could infiltrate the brain to phagocyte amyloid deposits. However, the molecular mechanisms involved in the amyloid peptide clearance remain unknown. Autophagy is a physiological degradation of proteins and organelles and can be controlled by pro-inflammatory cytokines. The purpose of this study was to evaluate the impact of inflammation on autophagy in PBMCs from AD patients at baseline, 12 and 24 months of follow-up. Furthermore, PBMCs from healthy patients were also included and treated with 20 μM amyloid peptide 1-42 to mimic AD environment. For each patient, PBMCs were stimulated with the mitogenic factor, phytohaemagglutin (PHA), and treated with either 1 μM C16 as an anti-inflammatory drug or its vehicle. Autophagic markers (Beclin-1, p62/sequestosome 1 and microtubule-associated protein-light chain 3: LC3) were quantified by western blot and cytokines (Interleukin (IL)-1β, Tumor necrosis Factor (TNF)-α and IL-6) by Luminex X-MAP® technology. Beclin-1 and TNF-α levels were inversely correlated in AD PBMCs at 12 months post-inclusion. In addition, Beclin-1 and p62 increased in the low inflammatory environment induced by C16. Only LC3-I levels were inversely correlated with cognitive decline at baseline. For the first time, this study describes longitudinal changes in autophagic markers in PBMCs of AD patients under an inflammatory environment. Inflammation would induce autophagy in the PBMCs of AD patients while an anti-inflammatory environment could inhibit their autophagic response. However, this positive response could be altered in a highly aggressive environment.

A novel cysteine cathepsin inhibitor yields macrophage cell death and mammary tumor regression

Although cysteine cathepsins have been identified as key regulators of cancer growth, their specific role in tumor development remains unclear. Recent studies have shown that high activity levels of tumor cathepsins are primarily a result of increased cathepsin activity in cancer-promoting tumor-associated macrophages (TAMs). To further investigate the role of cysteine cathepsin activity in normal and polarized macrophages, we established in vitro and in vivo models of macrophage differentiation and polarization and used a novel cysteine cathepsin inhibitor, GB111-NH2, to block the activity of cathepsins B, L and S. Here we show that in vitro, cysteine cathepsin inhibition yields both apoptosis and proliferation of macrophages, owing to increased oxidative stress. Proteomic analysis of cathepsin- inhibited macrophages demonstrates inhibition of autophagy, suggesting a likely cause of elevated reactive oxygen species (ROS) levels. In vivo models of mammary cancer further show that cathepsin inhibition yields TAM death owing to increased ROS levels. Strikingly, apoptosis in TAMs yields a seemingly cell non-autonomous death of neighboring cancer cells, and regression of the primary growth. These results show that cysteine cathepsin inhibitors can specifically trigger macrophage cell death and may function as an effective anticancer therapy in tumors with high levels of TAMs.

Complement 5a Enhances Hepatic Metastases of Colon Cancer via Monocyte Chemoattractant Protein-1-mediated Inflammatory Cell Infiltration

Complement 5a (C5a), a potent immune mediator generated by complement activation, promotes tumor growth; however, its role in tumor metastasis remains unclear. We demonstrate that C5a contributes to tumor metastases by modulating tumor inflammation in hepatic metastases of colon cancer. Colon cancer cell lines generate C5a under serum-free conditions, and C5a levels increase over time in a murine syngeneic colon cancer hepatic metastasis model. Furthermore, in the absence of C5a receptor or upon pharmacological inhibition of C5a production with an anti-C5 monoclonal antibody, tumor metastasis is severely impaired. A lack of C5a receptor in colon cancer metastatic foci reduces the infiltration of macrophages, neutrophils, and dendritic cells, and the role for C5a receptor on these cells were further verified by bone marrow transplantation experiments. Moreover, C5a signaling increases the expression of the chemokine monocyte chemoattractant protein-1 and the anti-inflammatory molecules arginase-1, interleukin 10, and transforming growth factor β, but is inversely correlated with the expression of pro-inflammatory molecules, which suggests a mechanism for the role of C5a in the inflammatory microenvironment required for tumor metastasis. Our results indicate a new and potentially promising therapeutic application of complement C5a inhibitor for the treatment of malignant tumors.

Selective cathepsin S inhibition attenuates atherosclerosis in apolipoprotein E-deficient mice with chronic renal disease

Chronic renal disease (CRD) accelerates the development of atherosclerosis. The potent protease cathepsin S cleaves elastin and generates bioactive elastin peptides, thus promoting vascular inflammation and calcification. We hypothesized that selective cathepsin S inhibition attenuates atherogenesis in hypercholesterolemic mice with CRD. CRD was induced by 5/6 nephrectomy in high-fat high-cholesterol fed apolipoprotein E-deficient mice. CRD mice received a diet admixed with 6.6 or 60 mg/kg of the potent and selective cathepsin S inhibitor RO5444101 or a control diet. CRD mice had significantly higher plasma levels of osteopontin, osteocalcin, and osteoprotegerin (204%, 148%, and 55%, respectively; P < 0.05), which were inhibited by RO5444101 (60%, 40%, and 36%, respectively; P < 0.05). Near-infrared fluorescence molecular imaging revealed a significant reduction in cathepsin activity in treated mice. RO5444101 decreased osteogenic activity. Histologic assessment in atherosclerotic plaque demonstrated that RO5444101 reduced immunoreactive cathepsin S (P < 0.05), elastin degradation (P = 0.01), plaque size (P = 0.01), macrophage accumulation (P < 0.01), growth differentiation factor-15 (P = 0.0001), and calcification (alkaline phosphatase activity, P < 0.01; osteocalcin, P < 0.05). Furthermore, cathepsin S inhibitor or siRNA significantly decreased expression of growth differentiation factor-15 and monocyte chemotactic protein-1 in a murine macrophage cell line and human primary macrophages. Systemic inhibition of cathepsin S attenuates the progression of atherosclerotic lesions in 5/6 nephrectomized mice, serving as a potential treatment for atherosclerosis in patients with CRD.

Longitudinal follow-up of autophagy and inflammation in brain of APPswePS1dE9 transgenic mice

Background

In recent years, studies have sought to understand the mechanisms involved in the alteration of autophagic flux in Alzheimer's disease (AD). Alongside the recent description of the impairment of lysosomal acidification, we wanted to study the relationships between inflammation and autophagy, two physiological components deregulated in AD. Therefore, a longitudinal study was performed in APPswePS1dE9 transgenic mice at three, six and twelve months of age.

Methods

Autophagic markers (Beclin-1, p62 and LC3) and the activation of mammalian Target of Rapamycin (mTOR) signaling pathway were quantified by western blot. Cytokine levels (IL-1β, TNF-α and IL-6) were measured by ELISA. Transmission electron microscopy was performed to detect autophagic vacuoles. Mann-Whitney tests were used to compare wild-type (WT) versus APPswePS1dE9 mice. Longitudinal changes in parameters were analyzed with a Kruskal-Wallis test followed by a post-hoc Dunn’s test. Correlation between two parameters was assessed using a Spearman test.

Results

Compared to 12-month old WT mice, 12-month old APPswePS1dE9 mice had higher levels of IL-1β and TNF-α, a greater inhibition of the mTOR signaling pathway and lower levels of Beclin-1 expression both in cortex and hippocampus. Regarding the relationship of the various parameters in 12-month old APPswePS1dE9 mice, Beclin-1 rates were positively correlated with IL-1β and TNF-α levels. And, on the contrary, TNF-α levels were inversely correlated with the levels of mTOR activation. Altogether, these results suggest that inflammation could induce autophagy in APPswePS1dE9 mice. However, these transgenic mice displayed a large accumulation of autophagic vesicles within dystrophic neurons in cortex and hippocampus, indicating a terminal failure in the autophagic process.

Conclusions

This first demonstration of relationships between inflammation and autophagy in in vivo models of AD should be taken into account in new therapeutic strategies to prevent inflammation and/or stimulate autophagy in advanced neurodegenerative process such as AD.