Thrombin increases inflammatory cytokine and angiogenic growth factor secretion in human adipose cells in vitro

The thrombin receptor PAR4 supports visceral adipose tissue inflammation

Thrombin inhibition suppresses adiposity, WAT inflammation and metabolic dysfunction in mice. Protease-activated receptor (PAR)1 does not account for thrombin-driven obesity, so we explored the culprit role of PAR4 in this context. Male WT and PAR-4-/- mice received a high fat diet (HFD) for 8 weeks, WT controls received standard chow. Body fat was quantified by NMR. Epididymal WAT was assessed by histology, immunohistochemistry, qPCR and lipase activity assay. 3T3-L1 preadipocytes were differentiated ± thrombin, acutely stimulated ± PAR4 activating peptide (AP) and assessed by immunoblot, qPCR and U937 monocyte adhesion. Epicardial adipose tissue (EAT) from obese and lean patients was assessed by immunoblot. PAR4 was upregulated in mouse WAT under HFD. PAR4-/- mice developed less visceral adiposity and glucose intolerance under HFD, featuring smaller adipocytes, fewer macrophages and lower expression of adipogenic (leptin, PPARγ) and pro-inflammatory genes (CCL2, IL-1β) in WAT. HFD-modified activity and expression of lipases or perilipin were unaffected by PAR4 deletion. 3T3-L1 adipocytes differentiated with thrombin retained Ki67 expression, further upregulated IL-1β and CCL2 and were more adhesive for monocytes. In mature adipocytes, PAR4-AP increased phosphorylated ERK1/2 and AKT, upregulated Ki67, CCl2, IL-β and hyaluronan synthase 1 but not TNF-α mRNA, and augmented hyaluronidase-sensitive monocyte adhesion. Obese human EAT expressed more PAR4, CD68 and CD54 than lean EAT. PAR4 upregulated in obesity supports adipocyte hypertrophy, WAT expansion and thrombo-inflammation. The emerging PAR4 antagonists provide a therapeutic perspective in this context beyond their canonical antiplatelet action.

Interruption of perivascular and perirenal adipose tissue thromboinflammation rescues prediabetic cardioautonomic and renovascular deterioration

The cardiovascular and renovascular complications of metabolic deterioration are associated with localized adipose tissue dysfunction. We have previously demonstrated that metabolic impairment delineated the heightened vulnerability of both the perivascular (PVAT) and perirenal adipose tissue (PRAT) depots to hypoxia and inflammation, predisposing to cardioautonomic, vascular and renal deterioration. Interventions either addressing underlying metabolic disturbances or halting adipose tissue dysfunction rescued the observed pathological and functional manifestations. Several lines of evidence implicate adipose tissue thromboinflammation, which entails the activation of the proinflammatory properties of the blood clotting cascade, in the pathogenesis of metabolic and cardiovascular diseases. Despite offering valuable tools to interrupt the thromboinflammatory cycle, there exists a significant knowledge gap regarding the potential pleiotropic effects of anticoagulant drugs on adipose inflammation and cardiovascular function. As such, a systemic investigation of the consequences of PVAT and PRAT thromboinflammation and its interruption in the context of metabolic disease has not been attempted. Here, using an established prediabetic rat model, we demonstrate that metabolic disturbances are associated with PVAT and PRAT thromboinflammation in addition to cardioautonomic, vascular and renal functional decline. Administration of rivaroxaban, a FXa inhibitor, reduced PVAT and PRAT thromboinflammation and ameliorated the cardioautonomic, vascular and renal deterioration associated with prediabetes. Our present work outlines the involvement of PVAT and PRAT thromboinflammation during early metabolic derangement and offers novel perspectives into targeting adipose tissue thrombo-inflammatory pathways for the management its complications in future translational efforts.

Mechanisms linking hypertriglyceridemia to acute pancreatitis

Hypertriglyceridemia (HTG) is a metabolic disorder, defined when serum or plasma triglyceride concentration (seTG) is >1.7 mM. HTG can be categorized as mild to very severe groups based on the seTG value. The risk of acute pancreatitis (AP), a serious disease with high mortality and without specific therapy, increases with the degree of HTG. Furthermore, even mild or moderate HTG aggravates AP initiated by other important etiological factors, including alcohol or bile stone. This review briefly summarizes the pathophysiology of HTG, the epidemiology of HTG-induced AP and the clinically observed effects of HTG on the outcomes of AP. Our main focus is to discuss the pathophysiological mechanisms linking HTG to AP. HTG is accompanied by an increased serum fatty acid (FA) concentration, and experimental results have demonstrated that these FAs have the most prominent role in causing the consequences of HTG during AP. FAs inhibit mitochondrial complexes in pancreatic acinar cells, induce pathological elevation of intracellular Ca²⁺ concentration, cytokine release and tissue injury, and reduce the function of pancreatic ducts. Furthermore, high FA concentrations can induce respiratory, kidney, and cardiovascular failure in AP. All these effects may contribute to the observed increased AP severity and frequent organ failure in patients. Importantly, experimental results suggest that the reduction of FA production by lipase inhibitors can open up new therapeutic options of AP. Overall, investigating the pathophysiology of HTG-induced AP or AP in the presence of HTG and determining possible treatments are needed.

Osteoporosis in hemophilia: what is its importance in clinical practice?

INTRODUCTION

The relationship between severe hemophilia and osteoporosis has been well established in the literature. However, although the importance of its prevention in order to reduce the risk of bone fractures has been reported, the importance of its treatment in clinical practice has not been well analyzed.

AREAS COVERED

In this paper a review of the available clinical and experimental information on osteoporosis in hemophilia has been performed, to better understand the relationship between hemophilia and osteoporosis. Prevention of osteoporosis in hemophilia should include primary hematological prophylaxis; a diet appropriate in calcium and vitamin D; a regular exercise program that includes aerobics, strength training and balance and flexibility activities; restriction of tobacco and alcohol use; and limitation of the duration of immobilization.

EXPERT OPINION

Prevention of osteoporosis in hemophilic patients is paramount. However, it is noteworthy that there is only one publication on the treatment of osteoporosis in patients with hemophilia. Until further research is done on this topic, the existing recommendations for non-hemophilic patients should be followed. They include the use of antiresorptives (estrogens, selective estrogen receptor modulators, bisphosphonates, denosumab) and anabolic agents (teriparatide, abaloparatide, romosozumab). Further studies on the management of osteoporosis in patients with hemophilia are required.

Immunomodulatory role of thrombin in cancer progression

Coagulation proteases and the generation of thrombin are increased in tumors. In addition, chemotherapeutic agents commonly used to treat malignant cancers can exacerbate cancer-associated thromboses. Thrombin can modify tumor cell behavior directly through the activation of protease-activated receptors (PAR) or indirectly by generating fibrin matrices. In addition to its role in generating fibrin to promote hemostasis, thrombin acts directly on multiple effector cells of the immune system impacting both acute and chronic inflammatory processes. Thrombin-mediated release of interleukin-6, tumor necrosis factor-α, and monocyte chemoattractant protein-1 leads to the accumulation of multiple tumor-infiltrating immunosuppressive cell populations including myeloid derived suppresser cells, M2-like macrophages, and T regulatory cells. Ablation of PAR-1 from the tumor microenvironment, but not the tumor, has been shown to dramatically reduce tumor growth and metastasis in multiple tumor models. Thrombin-activated platelets release immunosuppressive cytokines including transforming growth factor-β that can inhibit natural killer cell activity, helping tumor cells to evade host immunosurveillance. Taken together, there is strong evidence that thrombin influences cancer progression via multiple mechanisms, including the tumor immune response, with thrombin emerging as a target for novel therapeutic strategies for cancer.

Thromboinflammatory Processes at the Nexus of Metabolic Dysfunction and Prostate Cancer: The Emerging Role of Periprostatic Adipose Tissue

Simple Summary

As overweight and obesity increase among the population worldwide, a parallel increase in the number of individuals diagnosed with prostate cancer was observed. There appears to be a relationship between both diseases where the increase in the mass of fat tissue can lead to inflammation. Such a state of inflammation could produce many factors that increase the aggressiveness of prostate cancer, especially if this inflammation occurred in the fat stores adjacent to the prostate. Another important observation that links obesity, fat tissue inflammation, and prostate cancer is the increased production of blood clotting factors. In this article, we attempt to explain the role of these latter factors in the effect of increased body weight on the progression of prostate cancer and propose new ways of treatment that act by affecting how these clotting factors work.

Abstract

The increased global prevalence of metabolic disorders including obesity, insulin resistance, metabolic syndrome and diabetes is mirrored by an increased incidence of prostate cancer (PCa). Ample evidence suggests that these metabolic disorders, being characterized by adipose tissue (AT) expansion and inflammation, not only present as risk factors for the development of PCa, but also drive its increased aggressiveness, enhanced progression, and metastasis. Despite the emerging molecular mechanisms linking AT dysfunction to the various hallmarks of PCa, thromboinflammatory processes implicated in the crosstalk between these diseases have not been thoroughly investigated. This is of particular importance as both diseases present states of hypercoagulability. Accumulating evidence implicates tissue factor, thrombin, and active factor X as well as other players of the coagulation cascade in the pathophysiological processes driving cancer development and progression. In this regard, it becomes pivotal to elucidate the thromboinflammatory processes occurring in the periprostatic adipose tissue (PPAT), a fundamental microenvironmental niche of the prostate. Here, we highlight key findings linking thromboinflammation and the pleiotropic effects of coagulation factors and their inhibitors in metabolic diseases, PCa, and their crosstalk. We also propose several novel therapeutic targets and therapeutic interventions possibly modulating the interaction between these pathological states.

A pig BodyMap transcriptome reveals diverse tissue physiologies and evolutionary dynamics of transcription

A comprehensive transcriptomic survey of pigs can provide a mechanistic understanding of tissue specialization processes underlying economically valuable traits and accelerate their use as a biomedical model. Here we characterize four transcript types (lncRNAs, TUCPs, miRNAs, and circRNAs) and protein-coding genes in 31 adult pig tissues and two cell lines. We uncover the transcriptomic variability among 47 skeletal muscles, and six adipose depots linked to their different origins, metabolism, cell composition, physical activity, and mitochondrial pathways. We perform comparative analysis of the transcriptomes of seven tissues from pigs and nine other vertebrates to reveal that evolutionary divergence in transcription potentially contributes to lineage-specific biology. Long-range promoter–enhancer interaction analysis in subcutaneous adipose tissues across species suggests evolutionarily stable transcription patterns likely attributable to redundant enhancers buffering gene expression patterns against perturbations, thereby conferring robustness during speciation. This study can facilitate adoption of the pig as a biomedical model for human biology and disease and uncovers the molecular bases of valuable traits.

A comprehensive transcriptomic survey of the pig could enable mechanistic understanding of tissue specialization and accelerate its use as a biomedical model. Here the authors characterize four distinct transcript types in 31 adult pig tissues to dissect their distinct structural and transcriptional features and uncover transcriptomic variability related to tissue physiology.

Impact of Progesterone on Molecular Mechanisms of Preterm Premature Rupture of Membranes

The role and mechanisms of progesterone in preterm premature rupture of membranes (PPROM) remains unclear. This study aims to investigate the molecular mechanisms of action of progesterone in pre-labor full-term fetal amniotic membrane cells with and without stimulation by microbial, pro-inflammatory, or thrombogenic agents. Fetal amniotic membranes were collected from 30 women with a normal singleton pregnancy undergoing elective cesarean section at term prior to the onset of labor. The human amniotic epithelial cells isolated were pretreated with and without medroxyprogesterone acetate for 24 h. Then, cells were treated with and without TLR/NLR agonists, pro-inflammatory cytokines, or thrombin for 48 h. Semi-quantitative RT-PCR, Western blot, and caspase-3 activity measurement were performed. Progesterone stimulation decreased the expression of TLR2, TLR5, and Nod2 genes (alone and/or in combination with TLR/NLR agonists) and decreased the expression of IL-1β and IL-8 genes increased by stimulation with specific agonists for TLR2, TLR4, TLR5, Nod1, and Nod2. Moreover, progesterone decreased thrombin-induced IL-8 gene expression. Progesterone also decreased expression of Bax and Bid proteins (pro-apoptotic factors) increased by stimulation with pro-inflammatory cytokines (TNF-α, NGAL, IL-18, and IL-1β) and thrombin. Progesterone stimulation alone as well as co-stimulation with TNF-α, NGAL, IL-18, IL-1β, or thrombin with progesterone either increased, decreased, or did not change the expression of Bcl-2, Bcl-XL, or XIAP genes (anti-apoptotic factors). These data suggest progesterone plays protective roles against PPROM through anti-microbial, anti-inflammatory, and anti-thrombogenic actions on human-term fetal amniotic membrane cells. Progesterone alters pro-inflammatory cytokine- and thrombin-induced apoptosis by controlling the expression of pro-apoptotic and anti-apoptotic factors.

The pleiotropic effects of antithrombotic drugs in the metabolic-cardiovascular-neurodegenerative disease continuum: impact beyond reduced clotting

Antithrombotic drugs are widely used for primary and secondary prevention, as well as treatment of many cardiovascular disorders. Over the past few decades, major advances in the pharmacology of these agents have been made with the introduction of new drug classes as novel therapeutic options. Accumulating evidence indicates that the beneficial outcomes of some of these antithrombotic agents are not solely related to their ability to reduce thrombosis. Here, we review the evidence supporting established and potential pleiotropic effects of four novel classes of antithrombotic drugs, adenosine diphosphate (ADP) P2Y12-receptor antagonists, Glycoprotein IIb/IIIa receptor Inhibitors, and Direct Oral Anticoagulants (DOACs), which include Direct Factor Xa (FXa) and Direct Thrombin Inhibitors. Specifically, we discuss the molecular evidence supporting such pleiotropic effects in the context of cardiovascular disease (CVD) including endothelial dysfunction (ED), atherosclerosis, cardiac injury, stroke, and arrhythmia. Importantly, we highlight the role of DOACs in mitigating metabolic dysfunction-associated cardiovascular derangements. We also postulate that DOACs modulate perivascular adipose tissue inflammation and thus, may reverse cardiovascular dysfunction early in the course of the metabolic syndrome. In this regard, we argue that some antithrombotic agents can reverse the neurovascular damage in Alzheimer's and Parkinson's brain and following traumatic brain injury (TBI). Overall, we attempt to provide an up-to-date comprehensive review of the less-recognized, beneficial molecular aspects of antithrombotic therapy beyond reduced thrombus formation. We also make a solid argument for the need of further mechanistic analysis of the pleiotropic effects of antithrombotic drugs in the future.

Transcriptional Regulation of Thrombin-Induced Endothelial VEGF Induction and Proangiogenic Response

Thrombin, the ligand of the protease-activated receptor 1 (PAR1), is a well-known stimulator of proangiogenic responses in vascular endothelial cells (ECs), which are mediated through the induction of vascular endothelial growth factor (VEGF). However, the transcriptional events underlying this thrombin-induced VEGF induction and angiogenic response are less well understood at present. As reported here, we conducted detailed promotor activation and signal transduction pathway studies in human microvascular ECs, to decipher the transcription factors and the intracellular signaling events underlying the thrombin and PAR-1-induced endothelial VEGF induction. We found that c-FOS is a key transcription factor controlling thrombin-induced EC VEGF synthesis and angiogenesis. Upon the binding and internalization of its G-protein-coupled PAR-1 receptor, thrombin triggers ERK1/2 signaling and activation of the nuclear AP-1/c-FOS transcription factor complex, which then leads to VEGF transcription, extracellular secretion, and concomitant proangiogenic responses of ECs. In conclusion, exposure of human microvascular ECs to thrombin triggers signaling through the PAR-1–ERK1/2–AP-1/c-FOS axis to control VEGF gene transcription and VEGF-induced angiogenesis. These observations offer a greater understanding of endothelial responses to thromboinflammation, which may help to interpret the results of clinical trials tackling the conditions associated with endothelial injury and thrombosis.

Thrombin Inhibition by Argatroban: Potential Therapeutic Benefits in COVID-19

Thrombin is a trypsin-like serine protease with multiple physiological functions. Its role in coagulation and thrombosis is well-established. Nevertheless, thrombin also plays a major role in inflammation by activating protease-activated receptors. In addition, thrombin is also involved in angiogenesis, fibrosis, and viral infections. Considering the pathogenesis of COVID-19 pandemic, thrombin inhibitors may exert multiple potential therapeutic benefits including antithrombotic, anti-inflammatory, and antiviral activities. In this review, we describe the clinical features of COVID-19, the thrombin’s roles in various pathologies, and the potential of argatroban in COVID-19 patients. Argatroban is a synthetic, small molecule, direct, competitive, and selective inhibitor of thrombin. It is approved to parenterally prevent and/or treat heparin-induced thrombocytopenia in addition to other thrombotic conditions. Argatroban also possesses anti-inflammatory and antiviral activities and has a well-established pharmacokinetics profile. It also appears to lack a significant risk of drug–drug interactions with therapeutics currently being evaluated for COVID-19. Thus, argatroban presents a substantial promise in treating severe cases of COVID-19; however, this promise is yet to be established in randomized, controlled clinical trials.

A Pathophysiological Perspective on the SARS-CoV-2 Coagulopathy

Recent evidence is focusing on the presence of a hypercoagulable state with development of both venous and arterial thromboembolic complications in patients infected with SARS-CoV-2. The ongoing activation of coagulation related to the severity of the illness is further characterized by thrombotic microangiopathy and endotheliitis. These microangiopathic changes cannot be classified as classical disseminated intravascular coagulation (DIC). In this short review we describe the interaction between coagulation and inflammation with focus on the possible mechanisms that might be involved in SARS-CoV-2 infection associated coagulopathy in the critically ill.

Targeting perivascular and epicardial adipose tissue inflammation: therapeutic opportunities for cardiovascular disease

Major shifts in human lifestyle and dietary habits toward sedentary behavior and refined food intake triggered steep increase in the incidence of metabolic disorders including obesity and Type 2 diabetes. Patients with metabolic disease are at a high risk of cardiovascular complications ranging from microvascular dysfunction to cardiometabolic syndromes including heart failure. Despite significant advances in the standards of care for obese and diabetic patients, current therapeutic approaches are not always successful in averting the accompanying cardiovascular deterioration. There is a strong relationship between adipose inflammation seen in metabolic disorders and detrimental changes in cardiovascular structure and function. The particular importance of epicardial and perivascular adipose pools emerged as main modulators of the physiology or pathology of heart and blood vessels. Here, we review the peculiarities of these two fat depots in terms of their origin, function, and pathological changes during metabolic deterioration. We highlight the rationale for pharmacological targeting of the perivascular and epicardial adipose tissue or associated signaling pathways as potential disease modifying approaches in cardiometabolic syndromes.

P2Y12 Inhibition beyond Thrombosis: Effects on Inflammation

The P2Y₁₂ receptor is a key player in platelet activation and a major target for antithrombotic drugs. The beneficial effects of P2Y₁₂ receptor antagonists might, however, not be restricted to the primary and secondary prevention of arterial thrombosis. Indeed, it has been established that platelet activation also has an essential role in inflammation. Additionally, nonplatelet P2Y₁₂ receptors present in immune cells and vascular smooth muscle cells might be effective players in the inflammatory response. This review will investigate the biological and clinical impact of P2Y₁₂ receptor inhibition beyond its platelet-driven antithrombotic effects, focusing on its anti-inflammatory role. We will discuss the potential molecular and cellular mechanisms of P2Y₁₂-mediated inflammation, including cytokine release, platelet–leukocyte interactions and neutrophil extracellular trap formation. Then we will summarize the current evidence on the beneficial effects of P2Y₁₂ antagonists during various clinical inflammatory diseases, especially during sepsis, acute lung injury, asthma, atherosclerosis, and cancer.

Animal Models of Inflammation for Screening of Anti-inflammatory Drugs: Implications for the Discovery and Development of Phytopharmaceuticals

Inflammation is one of the common events in the majority of acute as well as chronic debilitating diseases and represent a chief cause of morbidity in today's era of modern lifestyle. If unchecked, inflammation leads to development of rheumatoid arthritis, diabetes, cancer, Alzheimer's disease, and atherosclerosis along with pulmonary, autoimmune and cardiovascular diseases. Inflammation involves a complex network of many mediators, a variety of cells, and execution of multiple pathways. Current therapy for inflammatory diseases is limited to the steroidal and non-steroidal anti-inflammatory agents. The chronic use of these drugs is reported to cause severe adverse effects like gastrointestinal, cardiovascular, and renal abnormalities. There is a massive need to explore new anti-inflammatory agents with selective action and lesser toxicity. Plants and isolated phytoconstituents are promising and interesting sources of new anti-inflammatories. However, drug development from natural sources has been linked with hurdles like the complex nature of extracts, difficulties in isolation of pure phytoconstituents, and the yield of isolated compounds in minute quantities that is insufficient for subsequent lead development. Although various in-vivo and in-vitro models for anti-inflammatory drug development are available, judicious selection of appropriate animal models is a vital step in the early phase of drug development. Systematic evaluation of phytoconstituents can facilitate the identification and development of potential anti-inflammatory leads from natural sources. The present review describes various techniques of anti-inflammatory drug screening with its advantages and limitations, elaboration on biological targets of phytoconstituents in inflammation and biomarkers for the prediction of adverse effects of anti-inflammatory drugs. The systematic approach proposed through present article for anti-inflammatory drug screening can rationalize the identification of novel phytoconstituents at the initial stage of drug screening programs.

The Effects of Graded Levels of Calorie Restriction: X. Transcriptomic Responses of Epididymal Adipose Tissue

Calorie restriction (CR) leads to a remarkable decrease in adipose tissue mass and increases longevity in many taxa. Since the discovery of leptin, the secretory abilities of adipose tissue have gained prominence in the responses to CR. We quantified transcripts of epididymal white adipose tissue of male C57BL/6 mice exposed to graded levels of CR (0–40% CR) for 3 months. The numbers of differentially expressed genes (DEGs) involved in NF-κB, HIF1-α, and p53 signaling increased with increasing levels of CR. These pathways were all significantly downregulated at 40% CR relative to 12 h ad libitum feeding. In addition, graded CR had a substantial impact on DEGs associated with pathways involved in angiogenesis. Of the 497 genes differentially expressed with graded CR, 155 of these genes included a signal peptide motif. These putative signaling proteins were involved in the response to ketones, TGF-β signaling, negative regulation of insulin secretion, and inflammation. This accords with the previously established effects of graded CR on glucose homeostasis in the same mice. Overall these data suggest reduced levels of adipose tissue under CR may contribute to the protective impact of CR in multiple ways linked to changes in a large population of secreted proteins.

Higher plane of nutrition pre-weaning enhances Holstein calf mammary gland development through alterations in the parenchyma and fat pad transcriptome

Background

To reduce costs of rearing replacement heifers, researchers have focused on decreasing age at breeding and first calving. To increase returns upon initiation of lactation the focus has been on increasing mammary development prior to onset of first lactation. Enhanced plane of nutrition pre-weaning may benefit the entire replacement heifer operation by promoting mammary gland development and greater future production.

Methods

Twelve Holstein heifer calves (< 1 week old) were reared on 1 of 2 dietary treatments (n = 6/group) for 8 weeks: a control group fed a restricted milk replacer at 0.45 kg/d (R, 20% crude protein, 20% fat), or an accelerated group fed an enhanced milk replacer at 1.13 kg/d (EH, 28% crude protein, 25% fat). At weaning (8 weeks), calves were euthanized and sub-samples of mammary parenchyma (PAR) and mammary fat pad (MFP) were harvested upon removal from the body. Total RNA from both tissues was extracted and sequenced using the Illumina HiSeq2500 platform. The Dynamic Impact Approach (DIA) and Ingenuity Pathway Analysis (IPA) were used for pathway analysis and functions, gene networks, and cross-talk analyses of the two tissues.

Results

When comparing EH vs R 1561 genes (895 upregulated, 666 downregulated) and 970 genes (506 upregulated, 464 downregulated) were differentially expressed in PAR and MFP, respectively. DIA and IPA results highlight a greater proliferation and differentiation activity in both PAR and MFP, supported by an increased metabolic activity. When calves were fed EH, the PAR displayed transcriptional signs of greater overall organ development, with higher ductal growth and branching, together with a supportive blood vessel and nerve network. These activities were mediated by intracellular cascades, such as AKT, SHH, MAPK, and Wnt, probably activated by hormones, growth factors, and endogenous molecules. The analysis also revealed strong communication between MFP and PAR.

Conclusion

The transcriptomics and bioinformatics approach highlighted key mechanisms that mediate the mammary gland response to a higher plane of nutrition in the pre-weaning period.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5303-8) contains supplementary material, which is available to authorized users.

Evidence for functional PAR-4 thrombin receptor expression in cardiac fibroblasts and its regulation by high glucose: PAR-4 in cardiac fibroblasts

BACKGROUND

Thrombin promotes cardiac fibroblast proliferation and fibrosis via protease-activated receptor (PAR-1). PAR-4 is reportedly absent in cardiac fibroblasts. In smooth muscle cells, PAR-4 expression is also low but increases upon hyperglycemia and contributes to vascular remodelling in diabetic mice. We examined if PAR-4 is a glucose-responsive gene with remodelling-related functions in cardiac fibroblasts.

METHODS AND RESULTS

Cardiac PAR-4 increased in mice with streptozotocin- or diabetogenic diet (DD)-induced diabetes. PAR-4 mRNA and protein were detectable in cardiac fibroblasts from chow-fed mice and increased in high (HG, 25mM) vs. low glucose (LG; 5.5mM) cultures. Conversely PAR-4 mRNA was higher in fibroblasts from DD-fed mice but reduced in LG cultures. Cardiac fibroblasts in HG culture responded more strongly to thrombin or PAR-4 activating peptide in terms of migration (wound-scratch assay), remodelling-associated gene expression (interleukin 6, alpha smooth muscle actin) and oxidative stress (dihydroethidium fluorescence).

CONCLUSION

PAR-4 is expressed in mouse cardiac fibroblasts and is dynamically regulated by extracellular glucose in vitro and diabetes in vivo, thereby impacting on fibroblast functions relevant for cardiac remodelling. These findings add further evidence for the usefulness of the recently developed PAR-4 antagonists in clinical settings.

Epithelial cell adhesion efficacy of a novel peptide identified by panning on a smooth titanium surface

Epithelial attachment via the basal lamina on the tooth surface provides an important structural defence mechanism against bacterial invasion in combating periodontal disease. However, when considering dental implants, strong epithelial attachment does not exist throughout the titanium-soft tissue interface, making soft tissues more susceptible to peri-implant disease. This study introduced a novel synthetic peptide (A10) to enhance epithelial attachment. A10 was identified from a bacterial peptide display library and synthesized. A10 and protease-activated receptor 4-activating peptide (PAR4-AP, positive control) were immobilized on commercially pure titanium. The peptide-treated titanium showed high epithelial cell migration ability during incubation in platelet-rich plasma. We confirmed the development of dense and expanded BL (stained by Ln5) with pericellular junctions (stained by ZO1) on the peptide-treated titanium surface. In an adhesion assay of epithelial cells on A10-treated titanium, PAR4-AP-treated titanium, bovine root and non-treated titanium, A10-treated titanium and PAR4-AP-treated titanium showed significantly stronger adhesion than non-treated titanium. PAR4-AP-treated titanium showed significantly higher inflammatory cytokine release than non-treated titanium. There was no significant difference in inflammatory cytokine release between A10-treated and non-treated titanium. These results indicated that A10 could induce the adhesion and migration of epithelial cells with low inflammatory cytokine release. This novel peptide has a potentially useful application that could improve clinical outcomes with titanium implants and abutments by reducing or preventing peri-implant disease.

Increased bone resorption in hemophilia

In patients with hemophilia, osteoporosis is frequently observed for which the etiology remains unclear. The aim of this paper is to review the available experimental evidence indicating the presence of this disorder in patients with hemophilia, explore the potential mechanisms which may lead to reduced bone mineral density (BMD) and speculate on useful interventions to circumvent it. A narrative review of the English literature up to April 2018 was performed. The available evidence demonstrates an increased rate of bone resorption and an excess of osteoporosis among patients with hemophilia. FVIII and FIX may act through at least two pathways: promoting bone formation by a thrombin-mediated mitogenic effect on osteoblasts and by cytokine-mediated osteoclast activity. Another potential indirect mechanism mediated through the RANK-RANKL pathway has been suggested but remains controversial. The role of confounders such as lack of activity and immobility must be considered.

The Role of Heparin Cofactor Ⅱ in the Regulation of Insulin Sensitivity and Maintenance of Glucose Homeostasis in Humans and Mice

Aim: Accelerated thrombin action is associated with insulin resistance. It is known that upon activation by binding to dermatan sulfate proteoglycans, heparin cofactor II (HCII) inactivates thrombin in tissues. Because HCII may be involved in glucose metabolism, we investigated the relationship between plasma HCII activity and insulin resistance.

Methods and Results: In a clinical study, statistical analysis was performed to examine the relationships between plasma HCII activity, glycosylated hemoglobin (HbA1c), fasting plasma glucose (FPG), and homeostasis model assessment-insulin resistance (HOMA-IR) in elderly Japanese individuals with lifestyle-related diseases. Multiple regression analysis showed significant inverse relationships between plasma HCII activity and HbA1c (p = 0.014), FPG (p = 0.007), and HOMA-IR (p = 0.041) in elderly Japanese subjects. In an animal study, HCII^+/+ mice and HCII^+/− mice were fed with a normal diet or high-fat diet (HFD) until 25 weeks of age. HFD-fed HCII^+/− mice exhibited larger adipocyte size, higher FPG level, hyperinsulinemia, compared to HFD-fed HCII^+/+ mice. In addition, HFD-fed HCII^+/− mice exhibited augmented expression of monocyte chemoattractant protein-1 and tumor necrosis factor, and impaired phosphorylation of the serine/threonine kinase Akt and AMP-activated protein kinase in adipose tissue compared to HFD-fed HCII^+/+ mice. The expression of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase was also enhanced in the hepatic tissues of HFD-fed HCII^+/− mice.

Conclusions: The present studies provide evidence to support the idea that HCII plays an important role in the maintenance of glucose homeostasis by regulating insulin sensitivity in both humans and mice. Stimulators of HCII production may serve as novel therapeutic tools for the treatment of type 2 diabetes.

Proinflammatory signaling functions of thrombin in cancer

Thrombin-induced activation of protease-activated receptors (PARs) represents a link between inflammation and cancer. Proinflammatory signaling functions of thrombin are associated with several inflammatory diseases including neurodegenerative, cardiovascular, and of special interest in this review cancer. Thrombin-induced inflammatory responses up-regulates expression of cytokines, adhesion molecules, angiogenic factors, and matrix-degrading proteases that facilitate tumor cells proliferation, angiogenesis, invasion, and metastasis. This review summarizes the current knowledge about the mechanisms of thrombin-mediated proinflammatory responses in cancer pathology for a better understanding and hence a better management of this disease.

Protein pathways working in human follicular fluid: the future for tailored IVF?

The human follicular fluid (HFF) contains molecules and proteins that may affect follicle growth, oocyte maturation and competence acquiring. Despite the numerous studies, an integrated broad overview on biomolecular and patho/physiological processes that are proved or supposed to take place in HFF during folliculogenesis and oocyte development is still missing. In this review we report, for the first time, all the proteins unambiguously detected in HFF and, applying DAVID (Database for Annotation, Visualization and Integrated Discovery) and MetaCore bioinformatic resources, we shed new lights on their functional correlation, delineating protein patterns and pathways with reasonable potentialities for oocyte quality estimation in in vitro fertilisation (IVF) programs. Performing a rigorous PubMed search, we redacted a list of 617 unique proteins unambiguously-annotated as HFF components. Their functional processing suggested the occurrence in HFF of a tight and highly dynamic functional-network, which is balanced by specific effectors, primarily involved in extracellular matrix degradation and remodelling, inflammation and coagulation. Metalloproteinases, thrombin and vitamin-D-receptor/retinoid-X-receptor-alpha resulted as the main key factors in the nets and their differential activity may be indicative of ovarian health and oocyte quality. Despite future accurate clinical investigations are absolutely needed, the present analysis may provide a starting point for more accurate oocyte quality estimation and for defining personalised therapies in reproductive medicine.

RNA-Seq Analysis of Abdominal Fat in Genetically Fat and Lean Chickens Highlights a Divergence in Expression of Genes Controlling Adiposity, Hemostasis, and Lipid Metabolism

Genetic selection for enhanced growth rate in meat-type chickens (Gallus domesticus) is usually accompanied by excessive adiposity, which has negative impacts on both feed efficiency and carcass quality. Enhanced visceral fatness and several unique features of avian metabolism (i.e., fasting hyperglycemia and insulin insensitivity) mimic overt symptoms of obesity and related metabolic disorders in humans. Elucidation of the genetic and endocrine factors that contribute to excessive visceral fatness in chickens could also advance our understanding of human metabolic diseases. Here, RNA sequencing was used to examine differential gene expression in abdominal fat of genetically fat and lean chickens, which exhibit a 2.8-fold divergence in visceral fatness at 7 wk. Ingenuity Pathway Analysis revealed that many of 1687 differentially expressed genes are associated with hemostasis, endocrine function and metabolic syndrome in mammals. Among the highest expressed genes in abdominal fat, across both genotypes, were 25 differentially expressed genes associated with de novo synthesis and metabolism of lipids. Over-expression of numerous adipogenic and lipogenic genes in the FL chickens suggests that in situ lipogenesis in chickens could make a more substantial contribution to expansion of visceral fat mass than previously recognized. Distinguishing features of the abdominal fat transcriptome in lean chickens were high abundance of multiple hemostatic and vasoactive factors, transporters, and ectopic expression of several hormones/receptors, which could control local vasomotor tone and proteolytic processing of adipokines, hemostatic factors and novel endocrine factors. Over-expression of several thrombogenic genes in abdominal fat of lean chickens is quite opposite to the pro-thrombotic state found in obese humans. Clearly, divergent genetic selection for an extreme (2.5-2.8-fold) difference in visceral fatness provokes a number of novel regulatory responses that govern growth and metabolism of visceral fat in this unique avian model of juvenile-onset obesity and glucose-insulin imbalance.

Comparison of venous thromboembolism after total hip arthroplasty between ankylosing spondylitis and osteoarthritis

Objective. Ankylosing spondylitis (AS), an inflammatory rheumatic disease, will gradually lead to severe hip joint dysfunction. Total hip arthroplasty is a useful method to improve patients' quality of life. The aim of this study was to compare the incidence and risk factors of deep vein thrombosis (DVT) between AS and hip osteoarthritis. Methods. In a retrospective study, a total of 149 subjects who underwent cementless THA were studied. Clinical data, biochemical data, and surgery-related data were measured between AS and OA groups. Results. The incidence of DVT in AS group was lower than that of OA group, although no significant difference was detected (P = 0.89). The patients of AS group were much younger (P < 0.0001) and thinner (P = 0.018) compared with those of OA group. AS patients had higher ejection fraction (EF) (P = 0.016), higher platelet counts (P < 0.0001), and lower hypertension rate (P = 0.0004). The values of APTT, PT, and INR in AS patients were higher than those in OA patients (all P < 0.0001). The values of D-dimer and APTT were both significantly higher in DVT subjects than those in non-DVT subjects. Conclusion. AS patients potentially had a lower incidence of DVT compared with OA patients.

Inflammation, obesity, and thrombosis

Clinical and epidemiological studies support a connection between obesity and thrombosis, involving elevated expression of the prothrombotic molecules plasminogen activator inhibitor-1 and tissue factor (TF) and increased platelet activation. Cardiovascular diseases and metabolic syndrome-associated disorders, including obesity, insulin resistance, type 2 diabetes, and hepatic steatosis, involve inflammation elicited by infiltration and activation of immune cells, particularly macrophages, into adipose tissue. Although TF has been clearly linked to a procoagulant state in obesity, emerging genetic and pharmacologic evidence indicate that TF signaling via G protein-coupled protease-activated receptors (PAR2, PAR1) additionally drives multiple aspects of the metabolic syndrome. TF-PAR2 signaling in adipocytes contributes to diet-induced obesity by decreasing metabolism and energy expenditure, whereas TF-PAR2 signaling in hematopoietic and myeloid cells drives adipose tissue inflammation, hepatic steatosis, and insulin resistance. TF-initiated coagulation leading to thrombin-PAR1 signaling also contributes to diet-induced hepatic steatosis and inflammation in certain models. Thus, in obese patients, clinical markers of a prothrombotic state may indicate a risk for the development of complications of the metabolic syndrome. Furthermore, TF-induced signaling could provide new therapeutic targets for drug development at the intersection between obesity, inflammation, and thrombosis.

Development of a multiplex sandwich aptamer microarray for the detection of VEGF165 and thrombin

In this work we have developed a multiplex microarray system capable of detecting VEGF₁₆₅ and thrombin. We recently described a Sandwich Aptamer Microarray (SAM) for thrombin detection feasible for use in multiplex microarrays; here we describe a new aptasensor for VEGF₁₆₅ detection employing Vap7 and VEa5, two DNA aptamers recognizing different sites of the protein. The aptamers were modified to be adapted to the solid phase platform of SAM and their capability to simultaneously recognize VEGF₁₆₅ by forming a ternary complex was analyzed in solution. Having so defined the best tandem arrangement of modified aptamers, we set up the aptasensor for VEGF₁₆₅, and finally analyzed the multiplex system with the two aptasensors for the simultaneous detection of VEGF₁₆₅ and thrombin. The results indicate that each sandwich is specific, even when the two proteins are mixed. The system performance is consistent with the behavior evidenced by the biochemical analysis, which proves to be valuable to drive the evaluation and refinement of aptamers prior to or along the development of a detection platform. Since thrombin upregulates VEGF expression, the simultaneous recognition of these two proteins could be useful in the analysis of biomarkers in pathologies characterized by neo-angiogenesis.

Thromboxane A2 receptor-mediated release of matrix metalloproteinase-1 (MMP-1) induces expression of monocyte chemoattractant protein-1 (MCP-1) by activation of protease-activated receptor 2 (PAR2) in A549 human lung adenocarcinoma cells

Matrix metalloproteinases (MMPs) and monocyte chemoattractant protein-1 (MCP-1, CCL2) are known to be upregulated in many tumors. Their roles in tumor invasion and metastasis are being uncovered. How they are related to each other and involved in tumor progression remains to be determined. Earlier it was reported that I-BOP-initiated activation of thromboxane A2 receptor (TP) induced the release of MMP-1, MMP-3, and MMP-9 from lung cancer A549 cells overexpressing TPα (A549-TPα). Herein it was found that MMP-1, but not MMP-3 or MMP-9, induced the expression of MCP-1 in A549 cells. Conditioned medium (CM) from I-BOP activated, MMP-1 siRNA pretreated A549-TPα cells induced greatly attenuated expression of MCP-1 in A549 cells indicating that MMP-1 in the CM contributed significantly to the expression of MCP-1. MMP-1 was shown to activate protease-activated receptor 2 (PAR2) instead of commonly assumed PAR1 to increase the expression of MCP-1 in A549 cells. This conclusion was reached from the following findings: (1) expression of MCP-1 induced by trypsin, a PAR2 agonist, and also PAR2 agonist peptide, was inhibited by a PAR2 antagonist; (2) expression of MCP-1 induced by MMP-1 and by CM from I-BOP activated A549-TPα cells was blocked by a PAR2 antagonist but not by other PAR antagonists; (3) expression of MCP-1 induced by MMP-1 and by CM from I-BOP activated A549-TPα cells was attenuated significantly by pretreatment of cells with PAR2-siRNA. These results suggest that PAR2 is a novel MMP-1 target mediating MMP-1-induced signals in A549 lung cancer cells.

RNA interference-based silencing reveals the regulatory role of fatty acid-binding protein 4 in the production of IL-6 and vascular endothelial growth factor in 3T3-L1 adipocytes

The fatty acid-binding protein 4 (FABP4) is believed to play an important role in maintaining glucose and lipid homeostasis. However, the physiological functions of FABP4 in adipocytes have not been fully elucidated because of difficulties associated with the effective transfection of small interfering RNA (siRNA) to differentiated adipocytes. The aim of this study was to clarify the physiological roles of FABP4 in adipocytes by establishing an efficient, universal technique for endogenous gene silencing in fully differentiated 3T3-L1 cells. Confocal-based three-dimensional observations demonstrated that, in traditionally cultured 3T3-L1 cells, multilayers of undifferentiated cells were formed. As a result, small interfering RNA failed to reach many of the differentiated cells. To solve this problem, we developed a reliable method, denoted as density-based separation followed by replating of enriched adipocytes in a monolayer (DREAM) and, using the developed method, succeeded in a significant knockdown of FABP4. Loss-of-function analyses revealed that FABP4 regulates the expression of IL-6 and vascular endothelial growth factor (VEGF) mediated by the protease-activated receptor 1 (PAR1), a thrombin receptor, in adipocytes. In addition, the basal IL-6 production was partially suppressed by PAR1 knockdown. Moreover, we also demonstrated that IL-6 stimulates the proliferation of primary endothelial cells isolated from murine adipose tissue. These findings indicate that FABP4 may have a crucial role in modulating IL-6 and vascular endothelial growth factor as angiogenesis inducers stimulated by the cellular action of thrombin on adipocytes via PAR1. These findings promise to be helpful for developing an understanding of physiological counterparts with respect to the inflammatory and angiogenic properties of adipose tissue.

Lipotoxicity causes multisystem organ failure and exacerbates acute pancreatitis in obesity

Obesity increases the risk of adverse outcomes during acute critical illnesses such as burns, severe trauma, and acute pancreatitis. Although individuals with more body fat and higher serum cytokines and lipase are more likely to experience problems, the roles that these characteristics play are not clear. We used severe acute pancreatitis as a representative disease to investigate the effects of obesity on local organ function and systemic processes. In obese humans, we found that an increase in the volume of intrapancreatic adipocytes was associated with more extensive pancreatic necrosis during acute pancreatitis and that acute pancreatitis was associated with multisystem organ failure in obese individuals. In vitro studies of pancreatic acinar cells showed that unsaturated fatty acids were proinflammatory, releasing intracellular calcium, inhibiting mitochondrial complexes I and V, and causing necrosis. Saturated fatty acids had no such effects. Inhibition of lipolysis in obese (ob/ob) mice with induced pancreatitis prevented a rise in serum unsaturated fatty acids and prevented renal injury, lung injury, systemic inflammation, hypocalcemia, reduced pancreatic necrosis, and mortality. Thus, therapeutic approaches that target unsaturated fatty acid-mediated lipotoxicity may reduce adverse outcomes in obese patients with critical illnesses such as severe acute pancreatitis.

The roles of thrombin and protease-activated receptors in inflammation

Inflammation and coagulation constitute two host defence systems with complementary physiological roles in limiting tissue damage, restoring homeostasis and eliminating invading pathogens, functions reliant on effective regulation of both processes at a variety of levels. Dysfunctional activation or regulation of either pathway may lead to pathology and contribute to human diseases as diverse as myocardial infarction and septic shock. The serine protease thrombin, a key protein in the coagulation pathway, can activate cellular signalling directly via proteolytic cleavage of the N-terminal domain of a family of G protein-coupled receptors or indirectly through the generation of molecules such as activated protein C. These events transmit signals to many cell types and can elicit the production of various pro-inflammatory mediators such as cytokines, chemokines and growth factors, thereby influencing cell activation, differentiation, survival and migration. This review discusses recent progress in understanding how thrombin and protease-activated receptors influence biological processes, highlighting the detrimental and protective cellular effects of thrombin and its signalling pathways.

Obesity and weight management in the elderly

Our population is ageing, and obesity is increasing in the elderly bringing massive and rapidly changing burdens of ill health related to increased body weights and fat as well as the main drivers of poor diet and inactivity. Overweight and obesity, and a static body mass index (BMI) commonly conceal sarcopenia (gain in body fat but loss of muscle mass and functional capacity) in older people, aggravated by inactivity. A systematic computerized literature search using an iterative manipulation process of the keywords: obesity, elderly, weight loss. The following databases were accessed on 20 October 2010: Medline, Cochrane Collaboration, Ovid and Scholar Google. A large number of clinical consequences of overweight and obesity are particularly problematic for elderly individuals, including type 2 diabetes mellitus, arthritis, urinary incontinence and depression. The observation that the BMI value associated with the lowest relative mortality is slightly higher in older than in younger adults has often been misinterpreted that obesity is not as harmful in the elderly. BMI may be a less appropriate index in the elderly. All the medical consequences of obesity are multi-factorial but all are alleviated by modest, achievable weight loss (5-10 kg) with an evidence-based maintenance strategy. Since sarcopenic obesity is common in the elderly, a combination of exercise and modest calorie restriction appears to be the optimal method of reducing fat mass and preserving muscle mass. Reduction in polypharmacy is a valuable target for weight management. Age is not an obstacle to weight management interventions using moderate calorie restriction and exercise, and the currently licensed drug orlistat appears to have no age-related hazards. Overall balance of clinical outcomes has not been evaluated. In older people the risks from bariatric surgery outweigh benefits. Obesity, and specifically sarcopenic obesity, should also be prevented not only from younger age, but also during major life transitions including retirement, to improve better health outcomes and quality of life in later years, with a focus on those in 'obese families', where the main increases in obesity are located. Randomized controlled trials to determine health benefits and risks from long-term weight management in obese elderly are necessary.