Cathepsin S contributes to macrophage migration via degradation of elastic fibre integrity to facilitate vein graft neointimal hyperplasia

Pyrocurzerenone suppresses human oral cancer cell metastasis by inhibiting the expression of ERK1/2 and cathepsin S proteins

Pyrocurzerenone is a natural compound found in Curcuma zedoaria and Chloranthus serratus. However, the anticancer effect of pyrocurzerenone in oral cancer remains unclear. Using the MTT assay, wound healing assay, transwell assay and western blot analysis, we investigated the impact of pyrocurzerenone on antimetastatic activity, as well as the critical signalling pathways that underlie the processes of oral cancer cell lines SCC-9, SCC-1 and SAS in this work. Our findings suggested that pyrocurzerenone inhibits cell migration and invasion ability in oral cancer cell lines. Furthermore, phosphorylation of ERK1/2 had significant inhibitory effects in SCC-9 and SCC-1 cell lines. Combining ERK1/2 inhibitors with pyrocurzerenone decreased the migration and invasion activity of SCC-9 and SCC-1 cell lines. We also found that the expressed level of cathepsin S decreased under pyrocurzerenone treatment. This study showed that pyrocurzerenone reduced ERK1/2 expression of the proteins and cathepsin S, suggesting that it could be a valuable treatment to inhibit human oral cancer cell metastasis.

Biomechanical dysregulation of SGK-1 dependent aortic pathologic markers in hypertension

Introduction

In hypertension (HTN), biomechanical stress may drive matrix remodeling through dysfunctional VSMC activity. Prior evidence has indicated VSMC tension-induced signaling through the serum and glucocorticoid inducible kinase-1 (SGK-1) can impact cytokine abundance. Here, we hypothesize that SGK-1 impacts production of additional aortic pathologic markers (APMs) representing VSMC dysfunction in HTN.

Methods

Aortic VSMC expression of APMs was quantified by QPCR in cyclic biaxial stretch (Stretch) +/- AngiotensinII (AngII). APMs were selected to represent VSMC dedifferentiated transcriptional activity, specifically Interleukin-6 (IL-6), Cathepsin S (CtsS), Cystatin C (CysC), Osteoprotegerin (OPG), and Tenascin C (TNC). To further assess the effect of tension alone, abdominal aortic rings from C57Bl/6 WT mice were held in a myograph at experimentally derived optimal tension (OT) or OT + 30% +/-AngII. Dependence on SGK-1 was assessed by treating with EMD638683 (SGK-1 inhibitor) and APMs were measured by QPCR. Then, WT and smooth muscle cell specific SGK-1 heterozygous knockout (SMC-SGK-1KO+/-) mice had AngII-induced HTN. Systolic blood pressure and mechanical stress parameters were assessed on Day 0 and Day 21. Plasma was analyzed by ELISA to quantify APMs. Statistical analysis was performed by ANOVA.

Results

In cultured aortic VSMCs, expression of all APMs was increased in response to biomechanical stimuli (Stretch +/-AngII,). Integrating the matrix contribution to signal transduction in the aortic rings led to IL-6 and CysC demonstrating SGK-1 dependence in response to elevated tension and interactive effect with concurrent AngII stimulation. CtsS and TNC, on the other hand, primarily responded to AngII, and OPG expression was unaffected in aortic ring experimentation. Both mouse strains had >30% increase in blood pressure with AngII infusion, reduced aortic distensibility and increased PPV, indicating increased aortic stiffness. In WT + AngII mice, IL-6, CtsS, CysC, and TNC plasma levels were significantly elevated, but these APMs were unaffected by HTN in the SMC-SGK-1KO+/- +AngII mice, suggesting SGK-1 plays a major role in VSMC biomechanical signaling to promote dysfunctional production of selected APMs.

Conclusion

In HTN, changes in the plasma levels of markers associated with aortic matrix homeostasis can reflect remodeling driven by mechanobiologic signaling in dysfunctional VSMCs, potentially through the activity of SGK-1. Further defining these pathways may identify therapeutic targets to reduce cardiovascular morbidity and mortality.

Nerve growth factor (Ngf) gene-driven semaphorin 3a (Sema3a) expression exacerbates thoracic aortic aneurysm dissection in mice

Thoracic aortic aneurysm and dissection (TAAD) is a life-threatening disease and currently there is no pharmacological therapy. Sympathetic nerve overactivity plays an important role in the development of TAAD. Sympathetic innervation is mainly controlled by nerve growth factor (NGF, a key neural chemoattractant) and semaphoring 3A (Sema3A, a key neural chemorepellent), while the roles of these two factors in aortic sympathetic innervation and especially TAAD are unknown. We hypothesized that genetically manipulating the NGF/Sema3A ratio by the Ngf -driven Sema3a expression approach may reduce aortic sympathetic nerve innervation and mitigate TAAD progression. A mouse strain of Ngf gene-driven Sema3a expression (namely NgfSema3a/Sema3a mouse) was established by inserting the 2A-Sema3A expression frame to the Ngf terminating codon using CRISPR/Cas9 technology. TAAD was induced by β-aminopropionitrile monofumarate (BAPN) both in NgfSema3a/Sema3a mice and wild type (WT) littermates. Contrary to our expectation, the BAPN-induced TAAD was severer in NgfSema3a/Sema3a mice than in wild-type (WT) mice. In addition, NgfSema3a/Sema3a mice showed higher aortic sympathetic innervation, inflammation and extracellular matrix degradation than the WT mice after BAPN treatment. The aortic vascular smooth muscle cells isolated from NgfSema3a/Sema3a mice and pretreated with BAPN in vivo for two weeks showed stronger capabilities of proliferation and migration than that from the WT mice. We conclude that the strategy of Ngf -driven Sema3a expression cannot suppress but worsens the BAPN-induced TAAD. By investigating the aortic phenotype of NgfSema3a/Sema3a mouse strain, we unexpectedly find a path to exacerbate BAPN-induced TAAD which might be useful in future TAAD studies.

Cathepsin S inhibition in dendritic cells prevents Th17 cell differentiation in perivascular adipose tissues following vascular injury in diabetic rats

In the context of diabetes mellitus (DM), the circulating cathepsin S (CTSS) level is significantly higher in the cardiovascular disease group. Therefore, this study was designed to investigate the role of CTSS in restenosis following carotid injury in diabetic rats. To induce DM, 60 mg/kg of streptozotocin (STZ) in citrate buffer was injected intraperitoneally into Sprague-Dawley rats. After successful modeling of DM, wire injury of the rat carotid artery was performed, followed by adenovirus transduction. Levels of blood glucose and Th17 cell surface antigens including ROR-γt, IL-17A, IL-17F, IL-22, and IL-23 in perivascular adipose tissues (PVAT) were evaluated. For in vitro analysis, human dendritic cells (DCs) were treated with 5.6-25 mM glucose for 24 h. The morphology of DCs was observed using an optical microscope. CD4+ T cells derived from human peripheral blood mononuclear cells were cocultured with DCs for 5 days. Levels of IL-6, CTSS, ROR-γt, IL-17A, IL-17F, IL-22 and IL-23 were measured. Flow cytometry was conducted to detect DC surface biomarkers (CD1a, CD83, and CD86) and Th17 cell differentiation. The collected DCs presented a treelike shape and were positive for CD1a, CD83, and CD86. Glucose impaired DC viability at the dose of 35 mM. Glucose treatment led to an increase in CTSS and IL-6 expression in DCs. Glucose-treated DCs promoted the differentiation of Th17 cells. CTSS depletion downregulated IL-6 expression and inhibited Th17 cell differentiation in vitro and in vivo. CTSS inhibition in DCs inhibits Th17 cell differentiation in PVAT tissues from diabetic rats following vascular injury.

The cathepsin-S/protease-activated receptor-(PAR)-2 axis drives chronic allograft vasculopathy and is a molecular target for therapeutic intervention

BACKGROUND

Cathepsin S (CatS) and proteinase-activated receptor (PAR)-2 are involved in the remodelling of vascular walls and neointima formation as well as in alloantigen presentation and T-cell priming. Therefore, we hypothesized that CatS/PAR-2 inhibition/deficiency would attenuate chronic allograft vasculopathy.

METHODS

Heterotopic aortic murine transplantation was performed from C57BL/6J donors to C57BL/6J recipients (syngeneic control group), Balb/c to C57BL/6J without treatment (allogenic control group), Balb/c to C57BL/6J with twice daily oral CatS inhibitor (allogenic treatment group) and Balb/c to Par2-/- C57BL/6J (allogenic knockout group). The recipients were sacrificed on day 28 and the grafts were harvested for histological analysis and RT-qPCR.

RESULTS

After 28 days, mice of the allogenic control group exhibited significant neointima formation and massive CD8 T-cell infiltration into the neointima while the syngeneic control group showed negligible allograft vasculopathy. The mRNA expression level of CatS in allografts was 5-fold of those in syngeneic grafts. Neointima formation and therefore intima/media-ratio were significantly decreased in the treatment and knockout group in comparison to the allogenic control group. Mice in treatment group also displayed significantly fewer CD8 T cells in the neointima compared with allogeneic controls. Additionally, treatment with the CatS inhibitor and PAR2-deficiency decreased mRNA-levels of interleukins and cytokines.

CONCLUSION

In conclusion, our data indicate that inhibiting CatS and PAR-2 deficiency led to a marked reduction of neointima formation and associated inflammation in a murine heterotopic model for allograft vasculopathy.

Cathepsin S (CTSS) activity in health and disease - A treasure trove of untapped clinical potential

Amongst the lysosomal cysteine cathepsin family of proteases, cathepsin S (CTSS) holds particular interest due to distinctive properties including a normal restricted expression profile, inducible upregulation and activity at a broad pH range. Consequently, while CTSS is well-established as a member of the proteolytic cocktail within the lysosome, degrading unwanted and damaged proteins, it has increasingly been shown to mediate a number of distinct, more selective roles including antigen processing and antigen presentation, and cleavage of substrates both intra and extracellularly. Increasingly, aberrant CTSS expression has been demonstrated in a variety of conditions and disease states, marking it out as both a biomarker and potential therapeutic target. This review seeks to contextualise CTSS within the cysteine cathepsin family before providing an overview of the broad range of pathologies in which roles for CTSS have been identified. Additionally, current clinical progress towards specific inhibitors is detailed, updating the position of the field in exploiting this most unique of proteases.

Combining a nanoparticle-mediated immunoradiotherapy with dual blockade of LAG3 and TIGIT improves the treatment efficacy in anti-PD1 resistant lung cancer

BACKGROUND

While improvements in immunoradiotherapy have significantly improved outcomes for cancer patients, this treatment approach has nevertheless proven ineffective at controlling the majority of malignancies. One of the mechanisms of resistance to immunoradiotherapy is that immune cells may be suppressed via the myriad of different immune checkpoint receptors. Therefore, simultaneous blockade of multiple immune checkpoint receptors may enhance the treatment efficacy of immunoradiotherapy.

METHODS

We combined NBTXR3-enhanced localized radiation with the simultaneous blockade of three different checkpoint receptors: PD1, LAG3, and TIGIT, and tested the treatment efficacy in an anti-PD1-resistant lung cancer model in mice. 129 Sv/Ev mice were inoculated with fifty thousand αPD1-resistant 344SQR cells in the right leg on day 0 to establish primary tumors and with the same number of cells in the left leg on day 4 to establish the secondary tumors. NBTXR3 was intratumorally injected into the primary tumors on day 7, which were irradiated with 12 Gy on days 8, 9, and 10. Anti-PD1 (200 µg), αLAG3 (200 µg), and αTIGIT (200 µg) were given to mice by intraperitoneal injections on days 5, 8, 11, 14, 21, 28, 35, and 42.

RESULTS

This nanoparticle-mediated combination therapy is effective at controlling the growth of irradiated and distant unirradiated tumors, enhancing animal survival, and is the only one that led to the destruction of both tumors in approximately 30% of the treated mice. Corresponding with this improved response is robust activation of the immune response, as manifested by increased numbers of immune cells along with a transcriptional signature of both innate and adaptive immunity within the tumor. Furthermore, mice treated with this combinatorial therapy display immunological memory response when rechallenged by the same cancer cells, preventing tumor engraftment.

CONCLUSION

Our results strongly attest to the efficacy and validity of combining nanoparticle-enhanced radiotherapy and simultaneous blockade of multiple immune checkpoint receptors and provide a pre-clinical rationale for investigating its translation into human patients.

Nicotine Modulates CTSS (Cathepsin S) Synthesis and Secretion Through Regulating the Autophagy-Lysosomal Machinery in Atherosclerosis

OBJECTIVE

Increased CTSS (cathepsin S) has been reported to play a critical role in atherosclerosis progression. Both CTSS synthesis and secretion are essential for exerting its functions. However, the underlying mechanisms contributing to CTSS synthesis and secretion in atherosclerosis remain unclear. Approach and Results: In this study, we showed that nicotine activated autophagy and upregulated CTSS expression in vascular smooth muscle cells and in atherosclerotic plaques. Western blotting and immunofluorescent staining showed that nicotine inhibited the mTORC1 (mammalian target of rapamycin complex 1) activity, promoted the nuclear translocation of TFEB (transcription factor EB), and upregulated the expression of CTSS. Chromatin immunoprecipitation-qualificative polymerase chain reaction, electrophoretic mobility shift assay, and luciferase reporter assay further demonstrated that TFEB directly bound to the CTSS promoter. mTORC1 inhibition by nicotine or rapamycin promoted lysosomal exocytosis and CTSS secretion. Live cell assays and IP-MS (immunoprecipitation-mass spectrometry) identified that the interactions involving Rab10 (Rab10, member RAS oncogene family) and mTORC1 control CTSS secretion. Nicotine promoted vascular smooth muscle cell migration by upregulating CTSS, and CTSS inhibition suppressed nicotine-induced atherosclerosis in vivo.

CONCLUSIONS

We concluded that nicotine mediates CTSS synthesis and secretion through regulating the autophagy-lysosomal machinery, which offers a potential therapeutic target for atherosclerosis treatment.

The Role of CARD9 in Metabolic Diseases

Caspase recruitment domain containing protein 9 (CARD9) is an adaptor protein that plays a critical role in pattern recognition receptors (PRRs)-mediated activation of NF-?B and mitogen-activated protein kinase (MAPK). This elicits initiation of the pro-inflammatory cytokines and leads to inflammatory responses, which has been recognized as a critical contributor to chronic inflammation. Current researches demonstrate that CARD9 is strongly associated with metabolic diseases, such as obesity, insulin resistance, atherosclerosis and so on. In this review, we summarize CARD9 signaling pathway and the role of CARD9 in metabolic diseases.

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.

Acute phase serum cathepsin S level and cathepsin S/cystatin C ratio are the associated factors with cerebral infarction and their diagnostic value for cerebral infarction

Cathepsin S plays an important role in the pathogenesis of several cardiovascular diseases; however, the relationship between serum cathepsin S and cerebral infarction (CI) is still unknown. This study aimed to investigate the relationship between acute phase serum cathepsin S level and cerebral infarction. A total of 202 stroke patients were enrolled into this study, and were divided into cerebral infarction (n = 140) group and non-cerebral infarction group (non-CI, n = 62). Fifty healthy individuals were recruited as the control group. Serum levels of cathepsin S and cystatin C were measured at days 1, 7, and 14 posthospitalization. Compared to the non-CI group, the CI group had significantly higher rates of hypertension, dyslipidemia, and smoking (all P < 0.05). The CI group had significantly higher cathepsin S levels and cathepsin S to cystatin C ratio (CatS/CysC) at both days 1 and 7 posthospitalization (both P < 0.05). Multivariate logistic regression analysis demonstrated that cathepsin S level (day 7) and CatS/CysC (days 1 and 7) were the associated factors with CI (all P < 0.05). Receiver operating characteristic (ROC) curve analysis revealed that the Area Under Curve (AUC) value of CatS-day7, CatS/CysC-day1, and CatS/CysC-day7 were 0.726 (95% CI: 0.652-0.800, P < 0.001), 0.641 (95% CI: 0.559-0.723, P = 0.001), and 0.721 (95% CI: 0.645-0.797, P = 0.039), respectively. Cathepsin S and CatS/CysC were associated with acute CI, and may have the potential to be the diagnostic biomarkers for CI. Our findings help to better understand the role of serum cathepsin S level in CI.

Cytochrome P450 1B1 Is Critical for Neointimal Growth in Wire-Injured Carotid Artery of Male Mice

Background We have reported that cytochrome P450 1B1 ( CYP 1B1), expressed in cardiovascular tissues, contributes to angiotensin II -induced vascular smooth muscle cell ( VSMC ) migration and proliferation and development of hypertension in various experimental animal models via generation of reactive oxygen species. This study was conducted to determine the contribution of CYP 1B1 to platelet-derived growth factor-BB-induced VSMC migration and proliferation in vitro and to neointimal growth in vivo. Methods and Results VSMC s isolated from aortas of male Cyp1b1 +/+ and Cyp1b1 -/- mice were used for in vitro experiments. Moreover, carotid arteries of Cyp1b1 +/+ and Cyp1b1 -/- mice were injured with a metal wire to assess neointimal growth after 14 days. Platelet-derived growth factor- BB -induced migration and proliferation and H2O2 production were found to be attenuated in VSMC s from Cyp1b1 -/- mice and in VSMC s of Cyp1b1 +/+ mice treated with 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl, a superoxide dismutase and catalase mimetic. In addition, wire injury resulted in neointimal growth, as indicated by increased intimal area, intima/media ratio, and percentage area of restenosis, as well as elastin disorganization and adventitial collagen deposition in carotid arteries of Cyp1b1 +/+ mice, which were minimized in Cyp1b1 -/- mice. Wire injury also increased infiltration of inflammatory and immune cells, as indicated by expression of CD 68+ macrophages and CD 3+ T cells, respectively, in the injured arteries of Cyp1b1 +/+ mice, but not Cyp1b1 -/- mice. Administration of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl attenuated neointimal growth in wire-injured carotid arteries of Cyp1b1 +/+ mice. Conclusions These data suggest that CYP 1B1-dependent oxidative stress contributes to the neointimal growth caused by wire injury of carotid arteries of male mice.

Role of cathepsin S In periodontal wound healing-an in vitro study on human PDL cells

Background

Cathepsin S is a cysteine protease, which is expressed in human periodontal ligament (PDL) cells under inflammatory and infectious conditions. This in vitro study was established to investigate the effect of cathepsin S on PDL cell wound closure.

Methods

An in vitro wound healing assay was used to monitor wound closure in wounded PDL cell monolayers for 72 h in the presence and absence of cathepsin S. In addition, the effects of cathepsin S on specific markers for apoptosis and proliferation were studied at transcriptional level. Changes in the proliferation rate due to cathepsin S stimulation were analyzed by an XTT assay, and the actions of cathepsin S on cell migration were investigated via live cell tracking. Additionally, PDL cell monolayers were treated with a toll-like receptor 2 agonist in the presence and absence of a cathepsin inhibitor to examine if periodontal bacteria can alter wound closure via cathepsins.

Results

Cathepsin S enhanced significantly the in vitro wound healing rate by inducing proliferation and by increasing the speed of cell migration, but had no effect on apoptosis. Moreover, the toll-like receptor 2 agonist enhanced significantly the wound closure and this stimulatory effect was dependent on cathepsins.

Conclusions

Our findings provide original evidence that cathepsin S stimulates PDL cell proliferation and migration and, thereby, wound closure, suggesting that this cysteine protease might play a critical role in periodontal remodeling and healing. In addition, cathepsins might be exploited by periodontal bacteria to regulate critical PDL cell functions.

Cysteine Protease Cathepsins in Atherosclerotic Cardiovascular Diseases

Atherosclerotic cardiovascular disease (ASCVD) is an inflammatory disease characterized by extensive arterial wall matrix protein degradation. Cysteine protease cathepsins play a pivotal role in extracellular matrix (ECM) remodeling and have been implicated in the development and progression of atherosclerosis-based cardiovascular diseases. An imbalance in expression between cathepsins (such as cathepsins S, K, L, C) and their inhibitor cystatin C may favor proteolysis of ECM in the pathogenesis of cardiovascular disease such as atherosclerosis, aneurysm formation, restenosis, and neovascularization. New insights into cathepsin functions have been made possible by the generation of knock-out mice and by the application of specific inhibitors. Inflammatory cytokines regulate the expression and activities of cathepsins in cultured vascular cells and macrophages. In addition, evaluations of the possibility of cathepsins as a diagnostic tool revealed that the circulating levels of cathepsin S, K, and L, and their endogenous inhibitor cystatin C could be promising biomarkers in the diagnosis of coronary artery disease, aneurysm, adiposity, peripheral arterial disease, and coronary artery calcification. In this review, we summarize the available information regarding the mechanistic contributions of cathepsins to ASCVD.

Sustained activation of ADP/P2ry12 signaling induces SMC senescence contributing to thoracic aortic aneurysm/dissection

Thoracic aortic aneurysm/dissection (TAAD) is characterized by excessive smooth muscle cell (SMC) loss, extracellular matrix (ECM) degradation and inflammation. However, the mechanism whereby signaling leads to SMC loss is unclear. We used senescence-associated (SA)-β-gal staining and analysis of expression of senescence-related proteins (p53, p21, p19) to show that excessive mechanical stretch (20% elongation, 3600cycles/h, 48h) induced SMC senescence. SMC senescence was also detected in TAAD specimens from both mice and humans. High-performance liquid chromatography and luciferin-luciferase-based assay revealed that excessive mechanical stretch increased adenosine diphosphate (ADP) release from SMCs both in vivo and in vitro. Elevated ADP induced SMC senescence while genetic knockout of the ADP receptor, P2Y G protein-coupled receptor 12 (P2ry12), in mice protected against SMC senescence and inflammation. Both TAAD formation and rupture were significantly reduced in P2ry12^-/- mice. SMCs from P2ry12^-/- mice were resistant to senescence induced by excessive mechanical stretch or ADP treatment. Mechanistically, ADP treatment sustained Ras activation, whereas pharmacological inhibition of Ras protected against SMC senescence and reduced TAAD formation. Taken together, excessive mechanical stress may induce a sustained release of ADP and promote SMC senescence via P2ry12-dependent sustained Ras activation, thereby contributing to excessive inflammation and degeneration, which provides insights into TAAD formation and progression.

CCL2 is transcriptionally controlled by the lysosomal protease cathepsin S in a CD74-dependent manner

Cathepsins S (CatS) has been implicated in numerous tumourigenic processes and here we document for the first time its involvement in CCL2 regulation within the tumour microenvironment. Analysis of syngeneic tumours highlighted reduced infiltrating macrophages in CatS depleted tumours. Interrogation of tumours and serum revealed genetic ablation of CatS leads to the depletion of several pro-inflammatory chemokines, most notably, CCL2. This observation was validated in vitro, where shRNA depletion of CatS resulted in reduced CCL2 expression. This regulation is transcriptionally mediated, as evident from RT-PCR analysis and CCL2 promoter studies. We revealed that CatS regulation of CCL2 is modulated through CD74 (also known as the invariant chain), a known substrate of CatS and a mediator of NFkB activity. Furthermore, CatS and CCL2 show a strong clinical correlation in brain, breast and colon tumours. In summary, these results highlight a novel mechanism by which CatS controls CCL2, which may present a useful pharmacodynamic marker for CatS inhibition.

Endoplasmic reticulum stress in bone marrow-derived cells prevents acute cardiac inflammation and injury in response to angiotensin II

Inflammation plays an important role in hypertensive cardiac injury. The endoplasmic reticulum (ER) stress pathway is involved in the inflammatory response. However, the role of ER stress in elevated angiotensin II (Ang II)-induced cardiac injury remains unclear. In this study, we investigated the role of ER stress in Ang II-induced hypertensive cardiac injury. Transcriptome analysis and quantitative real-time PCR showed that Ang II infusion in mice increased ER stress-related genes expression in the heart. C/EBP homologous protein (CHOP) deficiency, a key mediator of ER stress, increased infiltration of inflammatory cells, especially neutrophils, the production of inflammatory cytokines, chemokines in Ang II-infused mouse hearts. CHOP deficiency increased Ang II-induced cardiac fibrotic injury: (1) Masson trichrome staining showed increased fibrotic areas, (2) immunohistochemistry staining showed increased expression of α-smooth muscle actin, transforming growth factor β1 and (3) quantitative real-time PCR showed increased expression of collagen in CHOP-deficient mouse heart. Bone marrow transplantation experiments indicated that CHOP deficiency in bone marrow cells was responsible for Ang II-induced cardiac fibrotic injury. Moreover, TUNEL staining and flow cytometry revealed that CHOP deficiency decreased neutrophil apoptosis in response to Ang II. Taken together, our study demonstrated that hypertension induced ER stress after Ang II infusion. ER stress in bone marrow-derived cells protected acute cardiac inflammation and injury in response to Ang II.

Inflammatory cells, ceramides, and expression of proteases in perivascular adipose tissue adjacent to human abdominal aortic aneurysms

BACKGROUND

Abdominal aortic aneurysm (AAA) is a deadly irreversible weakening and distension of the abdominal aortic wall. The pathogenesis of AAA remains poorly understood. Investigation into the physical and molecular characteristics of perivascular adipose tissue (PVAT) adjacent to AAA has not been done before and is the purpose of this study.

METHODS AND RESULTS

Human aortae, periaortic PVAT, and fat surrounding peripheral arteries were collected from patients undergoing elective surgical repair of AAA. Control aortas were obtained from recently deceased healthy organ donors with no known arterial disease. Aorta and PVAT was found in AAA to larger extent compared with control aortas. Immunohistochemistry revealed neutrophils, macrophages, mast cells, and T-cells surrounding necrotic adipocytes. Gene expression analysis showed that neutrophils, mast cells, and T-cells were found to be increased in PVAT compared with AAA as well as cathepsin K and S. The concentration of ceramides in PVAT was determined using mass spectrometry and correlated with content of T-cells in the PVAT.

CONCLUSIONS

Our results suggest a role for abnormal necrotic, inflamed, proteolytic adipose tissue to the adjacent aneurysmal aortic wall in ongoing vascular damage.

Smad4 Deficiency in Smooth Muscle Cells Initiates the Formation of Aortic Aneurysm

RATIONALE

Aortic aneurysm is a life-threatening cardiovascular disorder caused by the predisposition for dissection and rupture. Genetic studies have proved the involvement of the transforming growth factor-β (TGF-β) pathway in aortic aneurysm. Smad4 is the central mediator of the canonical TGF-β signaling pathway. However, the exact role of Smad4 in smooth muscle cells (SMCs) leading to the pathogenesis of aortic aneurysms is largely unknown.

OBJECTIVE

To determine the role of smooth muscle Smad4 in the pathogenesis of aortic aneurysms.

METHODS AND RESULTS

Conditional gene knockout strategy combined with histology and expression analysis showed that Smad4 or TGF-β receptor type II deficiency in SMCs led to the occurrence of aortic aneurysms along with an upregulation of cathepsin S and matrix metallopeptidase-12, which are proteases essential for elastin degradation. We further demonstrated a previously unknown downregulation of matrix metallopeptidase-12 by TGF-β in the aortic SMCs, which is largely abrogated in the absence of Smad4. Chemotactic assay and pharmacologic treatment demonstrated that Smad4-deficient SMCs directly triggered aortic wall inflammation via the excessive production of chemokines to recruit macrophages. Monocyte/macrophage depletion or blocking selective chemokine axis largely abrogated the progression of aortic aneurysm caused by Smad4 deficiency in SMCs.

CONCLUSIONS

The findings reveal that Smad4-dependent TGF-β signaling in SMCs protects against aortic aneurysm formation and dissection. The data also suggest important implications for novel therapeutic strategies to limit the progression of the aneurysm resulting from TGF-β signaling loss-of-function mutations.

CARD9 mediates necrotic smooth muscle cell-induced inflammation in macrophages contributing to neointima formation of vein grafts

AIMS

Inflammation plays an important role in the neointima formation of grafted veins. However, the initiation of inflammation in grafted veins is still unclear. Here, we investigated the role and underlying mechanism of an innate immunity signalling protein, caspase-associated recruitment domain 9 (CARD9) in vein grafts in mice.

METHODS AND RESULTS

In early murine vein grafts, we observed robust death of smooth muscle cells (SMCs), which was accompanied by infiltration of macrophages and expression of pro-inflammatory cytokines. Meanwhile, SMC necrosis was associated with the expression of pro-inflammatory cytokines in macrophages in vitro. To explore the mediators of necrotic SMC-induced inflammation in grafted veins from mice, we examined the expression of CARD family proteins and found CARD9 highly expressed in infiltrated macrophages of grafted veins. CARD9-knockout (KO) inhibited necrotic SMC-induced pro-inflammatory cytokine expression and NF-κB activation. Furthermore, CARD9-KO suppressed necrotic SMC-induced expression of VEGF in macrophages. Finally, CARD9-KO decreased neointima formation of grafted veins in mice.

CONCLUSION

The innate immune protein CARD9 in macrophages may mediate necrotic SMC-induced inflammation by activating NF-κB and contributed to neointima formation in the vein grafts.

Mechanical stretch-induced endoplasmic reticulum stress, apoptosis and inflammation contribute to thoracic aortic aneurysm and dissection

Thoracic aortic aneurysm/dissection (TAAD) is characterized by excessive smooth muscle cell (SMC) loss, extracellular matrix (ECM) degradation and inflammation. In response to certain stimuli, endoplasmic reticulum (ER) stress is activated and regulates apoptosis and inflammation. Excessive apoptosis promotes aortic inflammation and degeneration, leading to TAAD. Therefore, we studied the role of ER stress in TAAD formation. A lysyl oxidase inhibitor, 3-aminopropionitrile fumarate (BAPN), was administrated to induce TAAD formation in mice, which showed significant SMC loss (α-SMA level). Excessive apoptosis (TUNEL staining) and ER stress (ATF4 and CHOP), along with inflammation, were present in TAAD samples from both mouse and human. Transcriptional profiling of SMCs after mechanical stress demonstrated the expression of genes for ER stress and inflammation. To explore the causal role of ER stress in initiating degenerative signalling events and TAAD, we treated wild-type (CHOP(+/+)) or CHOP(-/-) mice with BAPN and found that CHOP deficiency protected against TAAD formation and rupture, as well as reduction in α-SMA level. Both SMC apoptosis and inflammation were significantly reduced in CHOP(-/-) mice. Moreover, SMCs isolated from CHOP(-/-) mice were resistant to mechanical stress-induced apoptosis. Taken together, our results demonstrated that mechanical stress-induced ER stress promotes SMCs apoptosis, inflammation and degeneration, providing insight into TAAD formation and progression.

Proteinases and plaque rupture: unblocking the road to translation

PURPOSE OF REVIEW

To review progress over the past 5 years in relating extracellular proteinases to plaque rupture, the cause of most myocardial infarctions, and consider the most promising prospects for developing related treatments.

RECENT FINDINGS

Cysteinyl cathepsins have been implicated in multiple macrophage functions that could promote plaque rupture. Cathepsin K is an attractive target because it is a collagenase and selective inhibitors are already being used in phase III clinical trials. Several serine proteinases clearly influence vascular remodelling and atherogenesis but important, unrelated actions limit their value as therapeutic targets. Among the metalloproteinases, new evidence supports roles for A Disintigrin and Metalloproteinases (ADAMs), including ADAM-10, ADAM-17 and ADAM-33, which suggest that selective inhibitors might be effective treatments. For ADAMs with ThromboSpondin domains (ADAMTSs), there are biological and genome-wide association data linking ADAMTS-7 to incidence of coronary heart disease but not increased risk of myocardial infarctions. In the case of matrix metalloproteinases (MMPs), selective inhibitors of MMP-12 and MMP-13 are available and may be appropriate for development as therapies. Novel targets, including MMP-8, MMP-10, MMP-14, MMP-19, MMP-25 and MMP-28, are also being considered.

SUMMARY

New opportunities exist to exploit proteinases as therapeutic targets in plaque rupture.