Ischemia-reperfusion of rat myocardium activates nuclear factor-KappaB and induces neutrophil infiltration via lipopolysaccharide-induced CXC chemokine

Repair of the Infarcted Heart: Cellular Effectors, Molecular Mechanisms and Therapeutic Opportunities

The adult mammalian heart has limited endogenous regenerative capacity and heals through the activation of inflammatory and fibrogenic cascades that ultimately result in the formation of a scar. After infarction, massive cardiomyocyte death releases a broad range of damage-associated molecular patterns that initiate both myocardial and systemic inflammatory responses. TLRs (toll-like receptors) and NLRs (NOD-like receptors) recognize damage-associated molecular patterns (DAMPs) and transduce downstream proinflammatory signals, leading to upregulation of cytokines (such as interleukin-1, TNF-α [tumor necrosis factor-α], and interleukin-6) and chemokines (such as CCL2 [CC chemokine ligand 2]) and recruitment of neutrophils, monocytes, and lymphocytes. Expansion and diversification of cardiac macrophages in the infarcted heart play a major role in the clearance of the infarct from dead cells and the subsequent stimulation of reparative pathways. Efferocytosis triggers the induction and release of anti-inflammatory mediators that restrain the inflammatory reaction and set the stage for the activation of reparative fibroblasts and vascular cells. Growth factor-mediated pathways, neurohumoral cascades, and matricellular proteins deposited in the provisional matrix stimulate fibroblast activation and proliferation and myofibroblast conversion. Deposition of a well-organized collagen-based extracellular matrix network protects the heart from catastrophic rupture and attenuates ventricular dilation. Scar maturation requires stimulation of endogenous signals that inhibit fibroblast activity and prevent excessive fibrosis. Moreover, in the mature scar, infarct neovessels acquire a mural cell coat that contributes to the stabilization of the microvascular network. Excessive, prolonged, or dysregulated inflammatory or fibrogenic cascades accentuate adverse remodeling and dysfunction. Moreover, inflammatory leukocytes and fibroblasts can contribute to arrhythmogenesis. Inflammatory and fibrogenic pathways may be promising therapeutic targets to attenuate heart failure progression and inhibit arrhythmia generation in patients surviving myocardial infarction.

An In Vitro Alveolar Model Allows for the Rapid Assessment of Particles for Respiratory Sensitization Potential

Dust, both industrial and household, contains particulates that can reach the most distal aspects of the lung. Silica and nickel compounds are two such particulates and have known profiles of poor health outcomes. While silica is well-characterized, nickel compounds still need to be fully understood for their potential to cause long-term immune responses in the lungs. To assess these hazards and decrease animal numbers used in testing, investigations that lead to verifiable in vitro methods are needed. To understand the implications of these two compounds reaching the distal aspect of the lungs, the alveoli, an architecturally relevant alveolar model consisting of epithelial cells, macrophages, and dendritic cells in a maintained submerged system, was utilized for high throughput testing. Exposures include crystalline silica (SiO₂) and nickel oxide (NiO). The endpoints measured included mitochondrial reactive oxygen species and cytostructural changes assessed via confocal laser scanning microscopy; cell morphology evaluated via scanning electron microscopy; biochemical reactions assessed via protein arrays; transcriptome assessed via gene arrays, and cell surface activation markers evaluated via flow cytometry. The results showed that, compared to untreated cultures, NiO increased markers for dendritic cell activation, trafficking, and antigen presentation; oxidative stress and cytoskeletal changes, and gene and cytokine expression of neutrophil and other leukocyte chemoattractants. The chemokines and cytokines CCL3, CCL7, CXCL5, IL-6, and IL-8 were identified as potential biomarkers of respiratory sensitization.

Nitric Oxide in Cardiac Surgery: A Review Article

Perioperative organ injury remains a medical, social and economic problem in cardiac surgery. Patients with postoperative organ dysfunction have increases in morbidity, length of stay, long-term mortality, treatment costs and rehabilitation time. Currently, there are no pharmaceutical technologies or non-pharmacological interventions that can mitigate the continuum of multiple organ dysfunction and improve the outcomes of cardiac surgery. It is essential to identify agents that trigger or mediate an organ-protective phenotype during cardiac surgery. The authors highlight nitric oxide (NO) ability to act as an agent for perioperative protection of organs and tissues, especially in the heart-kidney axis. NO has been delivered in clinical practice at an acceptable cost, and the side effects of its use are known, predictable, reversible and relatively rare. This review presents basic data, physiological research and literature on the clinical application of NO in cardiac surgery. Results support the use of NO as a safe and promising approach in perioperative patient management. Further clinical research is required to define the role of NO as an adjunct therapy that can improve outcomes in cardiac surgery. Clinicians also have to identify cohorts of responders for perioperative NO therapy and the optimal modes for this technology.

Inflammation, dysregulated iron metabolism, and cardiovascular disease

Iron is an essential trace element associated with both pathologic deficiency and toxic overload. Thus, systemic and cell iron metabolism are highly controlled processes regulated by protein expression and localization, as well as turnover, through the action of cytokines and iron status. Iron metabolism in the heart is challenging because both iron overload and deficiency are associated with cardiac disease. Also associated with cardiovascular disease is inflammation, as many cardiac diseases are caused by or include an inflammatory component. In addition, iron metabolism and inflammation are closely linked. Hepcidin, the master regulator of systemic iron metabolism, is induced by the cytokine IL-6 and as such is among the acute phase proteins secreted by the liver as part of the inflammatory response. In an inflammatory state, systemic iron homeostasis is dysregulated, commonly resulting in hypoferremia, or low serum iron. Less well characterized is cardiac iron metabolism in general, and even less is known about how inflammation impacts heart iron handling. This review highlights what is known with respect to iron metabolism in the heart. Expression of iron metabolism-related proteins and processes of iron uptake and efflux in these cell types are outlined. Evidence for the strong co-morbid relationship between inflammation and cardiac disease is also reviewed. Known connections between inflammatory processes and iron metabolism in the heart are discussed with the goal of linking inflammation and iron metabolism in this tissue, a connection that has been relatively under-appreciated as a component of heart function in an inflammatory state. Therapeutic options connecting inflammation and iron balance are emphasized, with the main goal of this review being to bring attention to alterations in iron balance as a component of inflammatory diseases of the cardiovascular system.

Cotransplantation With Adipose Tissue-derived Stem Cells Improves Engraftment of Transplanted Hepatocytes

BACKGROUND

Hepatocyte transplantation is expected to be an alternative therapy to liver transplantation; however, poor engraftment is a severe obstacle to be overcome. The adipose tissue-derived stem cells (ADSCs) are known to improve engraftment of transplanted pancreatic islets, which have many similarities to the hepatocytes. Therefore, we examined the effects and underlying mechanisms of ADSC cotransplantation on hepatocyte engraftment.

METHODS

Hepatocytes and ADSCs were cotransplanted into the renal subcapsular space and livers of syngeneic analbuminemic rats, and the serum albumin level was quantified to evaluate engraftment. Immunohistochemical staining and fluorescent staining to trace transplanted cells in the liver were also performed. To investigate the mechanisms, cocultured supernatants were analyzed by a multiplex assay and inhibition test using neutralizing antibodies for target factors.

RESULTS

Hepatocyte engraftment at both transplant sites was significantly improved by ADSC cotransplantation ( P < 0.001, P < 0.001). In the renal subcapsular model, close proximity between hepatocytes and ADSCs was necessary to exert this effect. Unexpectedly, ≈50% of transplanted hepatocytes were attached by ADSCs in the liver. In an in vitro study, the hepatocyte function was significantly improved by ADSC coculture supernatant ( P < 0.001). The multiplex assay and inhibition test demonstrated that hepatocyte growth factor, vascular endothelial growth factor, and interleukin-6 may be key factors for the abovementioned effects of ADSCs.

CONCLUSIONS

The present study revealed that ADSC cotransplantation can improve the engraftment of transplanted hepatocytes. This effect may be based on crucial factors, such as hepatocyte growth factor, vascular endothelial growth factor, and interleukin-6, which are secreted by ADSCs.

The Role of CXC Chemokines in Cardiovascular Diseases

Cardiovascular disease (CVD) is a class of diseases with high disability and mortality rates. In the elderly population, the incidence of cardiovascular disease is increasing annually. Between 1990 and 2016, the age-standardised prevalence of CVD in China significantly increased by 14.7%, and the number of cardiovascular disease deaths increased from 2.51 million to 3.97 million. Much research has indicated that cardiovascular disease is closely related to inflammation, immunity, injury and repair. Chemokines, which induce directed chemotaxis of reactive cells, are divided into four subfamilies: CXC, CC, CX3C, and XC. As cytokines, CXC chemokines are similarly involved in inflammation, immunity, injury, and repair and play a role in many cardiovascular diseases, such as atherosclerosis, myocardial infarction, cardiac ischaemia-reperfusion injury, hypertension, aortic aneurysm, cardiac fibrosis, postcardiac rejection, and atrial fibrillation. Here, we explored the relationship between the chemokine CXC subset and cardiovascular disease and its mechanism of action with the goal of further understanding the onset of cardiovascular disease.

Soluble RAGE attenuates myocardial I/R injuries via FoxO3-Bnip3 pathway

Soluble receptor for advanced glycation end-products (sRAGE) was reported to inhibit cardiac apoptosis through the mitochondrial pathway during myocardial ischemia/reperfusion (I/R) injury. Meanwhile, the proapoptotic protein Bcl2 and adenovirus E1B 19-kDa-interacting protein 3 (Bnip3) was reported to mediate mitochondrial depolarization and be activated by the Forkhead box protein O3 (FoxO3a). Therefore, it is supposed that FoxO3a-Bnip3 pathway might be involved in the inhibiting effects of sRAGE on mitochondrial apoptosis during I/R. I/R surgery or glucose deprivation/reoxygenation was adopted to explore mitochondrial depolarization, apoptosis and related signaling pathways in mice hearts and cultured cardiomyocytes. The results showed that overexpression of sRAGE in cardiomyocytes dramatically improved cardiac function and reduced infarct areas in I/R treated mice. sRAGE inhibited mitochondrial depolarization and cardiac apoptosis during I/R, which correlated with reduced expression of Bnip3, Sirt2, phosphorylation of Akt and FoxO3a which translocated into nucleus in cultured cardiomyocytes. Either Sirt2 or FoxO3a silencing enhanced the inhibiting effects of sRAGE on mitochondrial depolarization induced by I/R in cultured cardiomyocytes. Meanwhile, overexpression or silencing of FoxO3a affected the inhibiting effects of sRAGE on Bnip3 and cleaved caspase-3 in cultured cardiomyocytes. Therefore, it is suggested that sRAGE inhibited I/R injuries via reducing mitochondrial apoptosis through the FoxO3a-Bnip3 pathway.

Role of Nitric Oxide and Protein S-Nitrosylation in Ischemia-Reperfusion Injury

Ischemia-reperfusion injury (IRI) is a process in which damage is induced in hypoxic tissue when oxygen supply is resumed after ischemia. During IRI, restoration of reduced nitric oxide (NO) levels may alleviate reperfusion injury in ischemic organs. The protective mechanism of NO is due to anti-inflammatory effects, antioxidant effects, and the regulation of cell signaling pathways. On the other hand, it is generally known that S-nitrosylation (SNO) mediates the detrimental or protective effect of NO depending on the action of the nitrosylated target protein, and this is also applied in the IRI process. In this review, the effect of each change of NO and SNO during the IRI process was investigated.

Cardioprotective Effect of Quercetin against Ischemia/Reperfusion Injury Is Mediated Through NO System and Mitochondrial K-ATP Channels

Objective

Quercetin (Que) is a plant-derived polyphenolic compound, that was shown to possess anti-inflammatory activity in myocardial ischemia/reperfusion (I/R) models in vivo; however, detailed mechanisms of its anti-inflammatory effects remain unclear. This study aimed to examine the effects of quercetin postconditioning (QPC) on I/R-induced inflammatory response in a rat model and evaluate the role of the mitochondrial K-ATP (mitoK_ATP) channels and NO system in this regard.

Materials and Methods

In this experimental study, hearts of male Wistar rats (250 ± 20 g) perused by Langendorff apparatus, were subjected to 30 minutes of global ischemia followed by 55 minutes reperfusion, and Que was added to the perfusion solution immediately at the onset of reperfusion. Creatine kinase (CK) levels in the coronary effluent were measured by spectrophotometry. Interleukin-1 (IL-1β), IL-6, and tumor necrosis factor-alpha (TNF-α) levels were analyzed by an enzyme-linked immunosorbent assay (ELISA) rat specific kit to assess the inflammatory condition of the myocardial tissue.

Results

Our results showed that QPC significantly improved left ventricular developed pressure (LVDP) (P<0.05), and decreased the CK release into the coronary effluent vs. control group (P<0.01). The levels of IL-1β (P<0.01), TNF-α (P<0.01), and IL-6 (P<0.05) were significantly diminished in Que-treated groups when compared to the control group. Inhibiting mitoK_ATPchannels by 100 μM 5-hydroxydecanoate and blocking NO system by 100 μM L-NAME reversed the cardioprotective effects of Que.

Conclusion

The findings of this study suggested that QPC exerts cardioprotective effects on myocardial I/R injury (MIRI) through inhibition of inflammatory reactions and improvement of contractility potential. Also, mitoK_ATP channels and NO system might be involved in this anti-inflammatory effect.

Post-ischemic Myocardial Inflammatory Response: A Complex and Dynamic Process Susceptible to Immunomodulatory Therapies

Following acute occlusion of a coronary artery causing myocardial ischemia and implementing first-line treatment involving rapid reperfusion, a dynamic and balanced inflammatory response is initiated to repair and remove damaged cells. Paradoxically, restoration of myocardial blood flow exacerbates cell damage as a result of myocardial ischemia-reperfusion (MI-R) injury, which eventually provokes accelerated apoptosis. In the end, the infarct size still corresponds to the subsequent risk of developing heart failure. Therefore, true understanding of the mechanisms regarding MI-R injury, and its contribution to cell damage and cell death, are of the utmost importance in the search for successful therapeutic interventions to finally prevent the onset of heart failure. This review focuses on the role of innate immunity, chemokines, cytokines, and inflammatory cells in all three overlapping phases following experimental, mainly murine, MI-R injury known as the inflammatory, reparative, and maturation phase. It provides a complete state-of-the-art overview including most current research of all post-ischemic processes and phases and additionally summarizes the use of immunomodulatory therapies translated into clinical practice.

Rno-microRNA-30c-5p promotes myocardial ischemia reperfusion injury in rats through activating NF-κB pathway and targeting SIRT1

Background

This study aimed to investigate the regulatory effect of rno-microRNA-30c-5p (rno-miR-30c-5p) on myocardial ischemia reperfusion (IR) injury in rats and the underlying molecular mechanisms.

Methods

A rat model of myocardial IR injury was established. The infarct size was detected by 2,3,5-triphenyltetrazolium chloride staining. The pathologic changes of myocardial tissues were detected by hematoxylin-eosin staining. The apoptosis of myocardial cells was measured by TUNEL staining and flow cytometry. The mRNA expression of rno-miR-30c-5p and Sirtuin 1 (SIRT1) was detected by quantitative real-time PCR. The levels of IL-1β, IL-6 and TNF-α were detected by enzyme linked immunosorbent assay. The protein expression of Bax, Bcl-2, caspase-3, p-IκBα, IκBα, p-NF-κB p65, NF-κB p65 and SIRT1 was detected by Western blot. The interaction between rno-miR-30c-5p and SIRT1 was predicted by TargetScan, and further identified by dual luciferase reporter gene and RNA immunoprecipitation assay.

Results

The myocardial IR injury model was successfully established in rats. IR induced the myocardial injury in rats and increased the expression of rno-miR-30c-5p. Overexpression of rno-miR-30c-5p enhanced the inflammation, promoted the apoptosis, and activated NF-κB pathway in IR myocardial cells. SIRT1 was the target gene of rno-miR-30c-5p. Silencing of SIRT1 reversed the effects of rno-miR-30c-5p inhibitor on the apoptosis and NF-κB pathway in IR myocardial cells.

Conclusions

Rno-miR-30c-5p promoted the myocardial IR injury in rats through activating NF-κB pathway and down-regulating SIRT1.

Chemokines in Myocardial Infarction

In the infarcted myocardium, cardiomyocyte necrosis triggers an intense inflammatory reaction that not only is critical for cardiac repair, but also contributes to adverse remodeling and to the pathogenesis of heart failure. Both CC and CXC chemokines are markedly induced in the infarcted heart, bind to endothelial glycosaminoglycans, and regulate leukocyte trafficking and function. ELR+ CXC chemokines (such as CXCL8) control neutrophil infiltration, whereas CC chemokines (such as CCL2) mediate recruitment of mononuclear cells. Moreover, some members of the chemokine family (such as CXCL10 and CXCL12) may mediate leukocyte-independent actions, directly modulating fibroblast and vascular cell function. This review manuscript discusses our understanding of the role of the chemokines in regulation of injury, repair, and remodeling following myocardial infarction. Although several chemokines may be promising therapeutic targets in patients with myocardial infarction, clinical implementation of chemokine-based therapeutics is hampered by the broad effects of the chemokines in both injury and repair.

Protective role of silibinin against myocardial ischemia/reperfusion injury-induced cardiac dysfunction

Silibinin is a traditional medicine and utilized for liver protection with antioxidant, anti-inflammation and anti-apoptosis properties. However, its role in myocardial I/R injury and the mechanism involved is currently unknown. In the present study, Silibinin treatment improves cardiac function and limits infarct size, and subsequently inhibits fibrotic remodeling in mice with myocardial I/R injury. Mechanistically, silibinin reduces cardiomyocytes apoptosis, attenuates mitochondrial impairment and endoplasmic reticulum (ER) stress, alleviates ROS generation, neutrophil infiltration and cytokines release. Consistently, silibinin prevents H9C2 cells from hypoxia/reperfusion-induced cell death, oxidative stress and inflammation in vitro. Furthermore, H9C2 cells treated with silibinin blocks NF-κB signaling activation by inhibiting IKKα phosphorylation, IκBα degradation and p65 NF-κB nuclear translocation during hypoxia/ reperfusion. In addition, silibinin plus BAY 11-7082 (a selected NF-κB inhibitor) do not provide incremental benefits in improving myocytes apoptosis, oxidative stress and inflammation in comparison with NF-κB signaling inhibition only. Thus, silibinin-mediated cardioprotection in myocardial I/R injury is associated with decreased apoptosis, oxidative stress and inflammatory response through deactivation of NF-κB pathway.

Apoptosis and autophagy in polycystic kidney disease (PKD)

Apoptosis in the cystic epithelium is observed in most rodent models of polycystic kidney disease (PKD) and in human autosomal dominant PKD (ADPKD). Apoptosis inhibition decreases cyst growth, whereas induction of apoptosis in the kidney of Bcl-2 deficient mice increases proliferation of the tubular epithelium and subsequent cyst formation. However, alternative evidence indicates that both induction of apoptosis as well as increased overall rates of apoptosis are associated with decreased cyst growth. Autophagic flux is suppressed in cell, zebra fish and mouse models of PKD and suppressed autophagy is known to be associated with increased apoptosis. There may be a link between apoptosis and autophagy in PKD. The mammalian target of rapamycin (mTOR), B-cell lymphoma 2 (Bcl-2) and caspase pathways that are known to be dysregulated in PKD, are also known to regulate both autophagy and apoptosis. Induction of autophagy in cell and zebrafish models of PKD results in suppression of apoptosis and reduced cyst growth supporting the hypothesis autophagy induction may have a therapeutic role in decreasing cyst growth, perhaps by decreasing apoptosis and proliferation in PKD. Future research is needed to evaluate the effects of direct autophagy inducers on apoptosis in rodent PKD models, as well as the cause and effect relationship between autophagy, apoptosis and cyst growth in PKD.

Adropin reduces hypoxia/reoxygenation-induced myocardial injury via the reperfusion injury salvage kinase pathway

Adropin is a secreted polypeptide that has been demonstrated to serve an important role in protecting the vascular endothelium. Pharmacological activation of pro-survival kinases, such as PI3K-Akt and ERK1/2, are involved in the reperfusion injury salvage kinase (RISK) pathway. In the present study, the effects of adropin in cardiomyocyte injury induced by simulated ischemia/reperfusion (SI/R) were assessed. Additionally, the current study also assessed the mechanisms that govern SI/R in a H9c2 cardiomyoblast cell model. Cell viability was measured using an MTT assay. Cell injury was assessed using creatine kinase MB measurements. Apoptosis was assessed using flow cytometry and caspase-3 activity. The inflammatory response was measured using tumor necrosis factor α and interleukin-10 expression. Oxidative stress was assessed using malondialdehyde and superoxide dismutase. The expression levels of Akt, ERK1/2, glycogen synthase kinase 3β (GSK3β), Bcl-2 and Bax were determined using western blot analysis. The results of the current study revealed that moderate-dose adropin increased cell viability, reduced early apoptosis and caspase-3 activity, promoted Bcl-2 expression, inhibited Bax and increased the Bcl-2/Bax ratio. Adropin significantly increased the phosphorylation of Akt, ERK1/2 and GSK3β, whereas inhibitors of PI3K and ERK1/2, respectively, LY294002 and PD98059, abolished the cardioprotective role of adropin. Furthermore, no significant difference was observed in phosphorylated-STAT3/total-STAT3 expression between the adropin and SI/R groups and Janus kinase 2 inhibitor AG490 did not significantly inhibit the protective role of adropin. These results indicate that adropin exerts a protective effect against SI/R injury through the RISK pathway instead of the survivor activating factor enhancement pathway.

The elevated CXCL5 levels in circulation are associated with lung function decline in COPD patients and cigarette smoking-induced mouse model of COPD

Introduction: C-X-C motif chemokine 5 is primarily chemotactic for neutrophils and previously shown to increase in the bronchoalveolar lavage fluid of patients with chronic obstructive pulmonary disease. However, whether C-X-C motif chemokine 5 levels correlate with lung function decline in patients or mouse model of chronic obstructive pulmonary disease was not clear. Methods: The mouse model was induced by cigarette smoke exposure. Plasma/serum and bronchoalveolar lavage fluid were obtained from patients and mouse model of chronic obstructive pulmonary disease; C-X-C motif chemokine 5 levels were assessed and correlated with lung functions and granulocyte-colony stimulating factor levels, respectively. Results: The C-X-C motif chemokine 5 levels increased and correlated to granulocyte-colony stimulating factor levels in both plasma/serum and bronchoalveolar lavage fluid obtained from patients and mouse model of chronic obstructive pulmonary disease. Circulating levels of C-X-C motif chemokine 5 correlated to lung functions decline in patients and mouse model. Conclusions: Granulocyte-colony stimulating factor might coordinate with C-X-C motif chemokine 5 in the pathogenesis of neutrophilic inflammation in chronic obstructive pulmonary disease. Circulating C-X-C motif chemokine 5 might serve as a potential blood-based biomarker to add additional modest predictive value on the preliminary screening and diagnosis of chronic obstructive pulmonary disease. Key messages Circulating C-X-C motif chemokine 5 might serve as a potential blood-based biomarker to add additional modest predictive value on the preliminary screening and diagnosis of COPD. Granulocyte-colony stimulating factor might coordinate with C-X-C motif chemokine 5 in the pathogenesis of neutrophilic inflammation in chronic obstructive pulmonary disease.

Matrix metalloproteinase-12 produced by Ly6Clow macrophages prolongs the survival after myocardial infarction by preventing neutrophil influx

BACKGROUND

Various immune cells are involved in different phases of cardiac repair after myocardial infarction (MI). Especially, Ly6C^low M2-like macrophages (Ly6C^lo macrophages) are vital for cardiac repair after MI. However, the molecular mechanisms how Ly6C^lo macrophages promote wound healing after MI are still largely unknown.

METHODS AND RESULTS

Transcriptome analysis of Ly6C^lo macrophages and Ly6C^high M1-like macrophages (Ly6C^hi macrophages) harvested from the infarcted heart revealed that Ly6C^lo macrophages highly expressed matrix metalloproteinase (MMP)-12 mRNA compared to Ly6C^hi macrophages. MMP-12 expression was enhanced in the infarcted heart and preferentially observed in Ly6C^lo macrophages. Importantly, the survival rate and cardiac function after MI were significantly impaired in MMP-12-deficient (mmp12^-/-) mice compared with those in wild-type mice. In addition, the extent of myocardial fibrosis and the number of myofibroblasts in the infarct area were decreased in mmp12^-/- mice. MMP-9 expression and neutrophils, which are the major cellular source of MMP-9, in the infarcted heart were increased in mmp12^-/- mice. Moreover, mRNA expression of neutrophil-attracting chemokines including CXCL1, CXCL2, and CXCL5 was significantly higher in mmp12^-/- mice. Consistently, treatment with anti-CXCR2 antibody significantly decreased neutrophil numbers and MMP-9 expression in the infarcted heart in mmp12^-/- mice. Finally, the administration of recombinant MMP-12 into the infarcted heart decreased neutrophil numbers in the infarcted heart and promoted wound healing in both wild-type mice and mmp12^-/- mice.

CONCLUSION

MMP-12 produced by Ly6C^lo macrophages improves the survival after MI possibly through the promotion of wound healing by reducing neutrophil infiltration.

Lack of scarring is not always a sign of cardiac health: Functional and molecular characterization of the rat heart's following chronic reperfusion

Even though the coronary reperfusion process is the most important tool to preserve cardiac function, after myocardial infarction, reperfusion of acutely ischemic myocardium can induce injury. We aimed to evaluate the functional and molecular aspects 4 weeks after myocardial ischemia-reperfusion (IR) in rats. Male Wistar rats (N = 47) were subjected to myocardial IR by short-term (30 min) ligation and subsequent reperfusion of the left descending coronary artery. Control rats (N = 7) underwent the same surgical maneuver without coronary ligation. After 4 weeks, rats had their cardiac function examined by ventricular pressure recording under basal condition or pharmacological stress. Myocardial fibrosis and molecular mediators of IR injury (reactive oxygen species, tumor necrosis factor-alpha and matrix-metalloproteinase-2) were assessed as well. Most of the rats subjected to IR did not show macroscopic signs of infarct, while only 17% of these animals showed large myocardial infarction scars. Of note, all animals submitted to IR presented the functional and molecular parameters altered when compared with the control subjects. Cardiac function was attenuated in all animals submitted to IR, regardless the presence or size of macroscopic cardiac scars. Interstitial fibrosis, matrix-metalloproteinase-2 activity and the expression of tumor necrosis factor-alpha were higher in the myocardium of all IR rats as compared to the control subjects (p<0.05). Myocardium superoxide anion and hydrogen peroxide were increased in rats without or with mild cardiac scars. These results show that IR leads to myocardial injury in rats. Besides, even the animals with an apparent healthy myocardium (without infarct scar) presented cardiac dysfunction and molecular changes that may contribute to the development of heart failure over time.

Immunomodulation by Exosomes in Myocardial Infarction

Exosomes are important carriers of biological information that facilitate intercellular communication and participate in the pathophysiology of different cardiovascular diseases. Myocardial infarction is among the leading causes of death worldwide. Upon myocardial infarction, massive cardiomyocyte death triggers a strong inflammatory response which is a vital process of cardiac injury, repair, and remodeling. Increasing evidence has unveiled that exosomes are involved in the inflammatory response and immune regulation after myocardial infarction. In this review, we will summarize the biological function of exosomes in the pathophysiology of myocardial infarction, especially focusing on their roles in the modulation of inflammation and immune response after myocardial infarction which further influences myocardial repair and remodeling. We will also discuss the immunomodulation by exosomes derived from stem and progenitor cells in the treatment of myocardial infarction. A deep understanding of immunomodulation by exosomes may represent a promising therapeutic option for the treatment of myocardial infarction.

The pathophysiology of myocardial infarction-induced heart failure

Heart failure (HF) is a multifactorial disorder and is usually the end stage of many cardiovascular diseases (CVD). HF presents one of the highest morbidity and mortality indices worldwide and high costs to public health organizations. Myocardial infarction (MI) is the most prevalent CVD in the Western world and leads to HF when its management is inadequate. It has a destructive potential for heart cells and abruptly reduces the cardiac output, a clinical condition known as heart dysfunction that might progress to HF. Many acute and chronic adaptations occur due to MI that progress to HF, e.g., neurohumoral hyperactivity, inflammatory response and cardiac remodeling. Herein, we reviewed in simplistic manner the processes involved in setting of MI until the establishment of HF.

Relationship Between Prodromal Angina Pectoris and Neutrophil-to Lymphocyte Ratio in Patients With ST Elevation Myocardial Infarction

BACKGROUND

The aim of this study was to investigate the relationship between prodromal angina (PA) with neutrophil-to-lymphocyte ratio (NLR) in patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

The study group included 145 patients with STEMI who underwent emergency coronary angiography (CA) within 24hours of symptom onset. Data were collected regarding whether patients had experienced PA before acute myocardial infarction. Seventy-three (73) patients (50.3%) had prodromal angina. Prodromal angina positive and negative groups were compared for demographic characteristics, complete blood count parameters including NLR, blood biochemistry parameters and left ventricular ejection fraction (LVEF).

RESULTS

Neutrophil count, NLR, and troponin I levels were significantly higher in the PA negative group. LVEF after reperfusion and lymphocyte count were lower in the PA negative group. In multivariate regression analysis, NLR (β=-0.419, p<0.001) and LVEF (β=0.418, p<0.001) were found to be significantly associated with the presence of PA in STEMI patients.

CONCLUSIONS

Absence of PA was significantly and independently associated with increased NLR and impaired LVEF after reperfusion, and increased NLR was found as a significant predictor for both lack of PA and impaired LVEF in STEMI patients.

Prognostic Association of Circulating Neutrophil Count with No-Reflow in Patients with ST-Segment Elevation Myocardial Infarction following Successful Primary Percutaneous Intervention

Objective

The aim of the present study was to investigate the predictive value of neutrophil count for no-reflow in patients with ST-segment elevation myocardial infarction (STEMI) who underwent successful primary percutaneous intervention (PCI).

Methods

We conducted a retrospective study of 361 patients diagnosed with acute STEMI between 2011 and 2015. All patients underwent successful PCI within 12 h from the onset of symptoms. Angiographic no-reflow was diagnosed based on a post-PCI thrombolysis in myocardial infarction flow grade ≤ 2 without mechanical obstruction. According to a neutrophil count cut-off determined by receiver operating characteristic curve analysis, patients were divided into two groups: group A (neutrophil count < 9.14 × 10⁹/L) and group B (neutrophil count ≥ 9.14 × 10⁹/L).

Results

Compared to patients in the normal reflow group, patients with no-reflow had higher neutrophil counts (P < 0.05). The incidence rate of no-reflow in group A (18, 9.3%) was significantly lower than that in group B (38). Multivariate logistic regression analysis revealed that a neutrophil count ≥ 9.14 × 10⁹/L was independently predictive for no-reflow (odds ratio = 4.474, 95% confidence interval: 1.610–12.433, P = 0.004) after adjusting for potential confounders.

Conclusions

A circulating neutrophil count ≥ 9.14 × 10⁹/L is independently associated with no-reflow in patients with acute STEMI following primary PCI.

Fracture initiates systemic inflammatory response syndrome through recruiting polymorphonuclear leucocytes

Fracture, a common type injury in trauma patients, often results in the development of the systemic inflammatory response syndrome (SIRS). Though the mechanism of the fracture-initiated SIRS still remains not well characterized, it is well documented that the polymorphonuclear leucocytes (PMN) play an important role in the inflammatory process. We hypothesize that fractures recruit PMN to the local tissue, which is followed by an increase in the number of peripheral PMN and initiation of SIRS. In the current study, we established a closed femoral fracture rat model. We evaluated the levels of MPO, IL-1β and CINC-1 in fractured tissue homogenate, and we measured the levels of IL-6 and IL-10, the biomarkers for systemic inflammatory response, in the rat sera. In clinical part of the study, we collected blood from patients with isolated closed femoral fractures and evaluated PMN-related chemoattractants (IL-8, IL-1β and G-CSF) and the number of peripheral PMN. We further evaluated the level of mitochondrial DNA in the local haematoma of fracture and the circulating plasma of the patients with fracture. In the animal model of closed femoral fracture, we found a significant recruitment of PMN to the local tissue after fracture, which correlates with the elevated MPO level. We also showed that the concentration of IL-1β and CINC-1 in local tissue is significantly increased and might be responsible for the PMN recruitment. Recruitment of PMN to the local tissue was accompanied with a significant increase in the systemic levels of IL-6 and IL-10 in serum. In the patients with closed femoral fracture, we observed an increase in the number of peripheral PMN and PMN-related chemoattractants, including IL-8, IL-1β and G-CSF. The level of mitochondrial DNA in the local haematoma of fracture and the circulating plasma of patients were significantly higher compared to the healthy volunteers. Our data suggest that fracture released mitochondrial DNA into the local haematoma of fracture, which recruited the PMN into the local tissue via chemokines (IL-1β and CINC-1), then increased the numbers of peripheral PMN and SIRS related cytokines in serum (IL-6 and IL-10). This might be the mechanism of the fracture-initiated SIRS.

Overexpression of microRNA-146 protects against oxygen-glucose deprivation/recovery-induced cardiomyocyte apoptosis by inhibiting the NF-κB/TNF-α signaling pathway

MicroRNA (miR) has been reported to be associated with ischemia and reperfusion (I/R) and cell apoptosis. Suppression of cell apoptosis may reduce the irreversible damage induced by reperfusion. The aims of the current study were to explore the cytoprotective effects of miR-146 against oxygen-glucose deprivation/recovery (OGD/R)-induced injury in H9c2 rat myocardial cells, as well as the underlying mechanisms. Following stimulation with OGD/R, the cells were transfected with miR-146 mimics or negative controls. The levels of miR-146 were analyzed by reverse transcription-quantitative polymerase chain reaction. Thereafter, cell viability and cell apoptosis were analyzed by MTT assay and terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling assay, respectively. In addition, the levels of tumor necrosis factor (TNF)-α were determined by ELISA and the levels of B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax), Bcl-2 and phosphorylated (p)-nuclear factor (NF)-κB were measured by western blotting. The results demonstrated that overexpression of miR-146 significantly increased cell viability and decreased apoptosis (P<0.05). It was observed that overexpression of miR-146 statistically reduced the levels of Bax, TNF-α and p-NF-κB but markedly upregulated the levels of Bcl-2 (P<0.05). These results indicate that overexpression of miR-146 may protect against OGD/R-induced cardiomyocyte apoptosis. Overexpression of miR-146 may alleviate the irreversible injury associated with reperfusion and the effects may be achieved by inhibiting the NF-κB/TNF-α signaling pathway.

Epothilone B impairs functional recovery after spinal cord injury by increasing secretion of macrophage colony-stimulating factor

The microtubule-stabilizing drug epothilone B (epoB) has shown potential value in the treatment of spinal cord injury (SCI) through diverse mechanisms. However, it remains elusive why a limited overall effect was observed. We aim to investigate the limiting factors underlying functional recovery promoted by epoB. The same SCI model treated by epoB was established as discussed previously. We used a cerebrospinal fluid (CSF) sample to assess the changes in cytokines in milieu of the SCI lesion site after epoB treatment. We then analyzed the source of cytokines, the state of microglia/macrophages/monocytes (M/Ms), and the recruitment of neutrophil in the lesion site by using the results of antibody array. Following these findings, we further evaluated the motor functional recovery caused by the reshaped microenvironment. Systemic administration of epoB significantly increased levels of several cytokines in the CSF of the rat SCI model; macrophage colony-stimulating factor (M-CSF) secreted by intact central nervous system (CNS) cells was one of the cytokines with increased levels. Along with epoB and other cytokines, M-CSF reshapes the SCI milieu by activating the microglias, killing bone marrow-derived macrophages, polarizing the M/M to M1 phenotype, and activating downstream cytokines to exacerbate the SCI injury, but it also increases the expression of neurotrophic factors. Anti-inflammatory therapy using a neutralizing antibody mix shows encouraging results. Using in vivo experiments, our findings indicate that epoB inhibits the SCI functional recovery in many ways by reshaping the milieu, which counteracts the therapeutic efficacy that led to the limited overall effectiveness.

Expression and Role of the Calcium-Sensing Receptor in Rat Peripheral Blood Polymorphonuclear Neutrophils

The calcium-sensing receptors (CaSRs) play an important role in many tissues and organs that are involved in inflammatory reactions. Peripheral blood polymorphonuclear neutrophils (PMNs) are important inflammatory cells. However, the expression and functions of CaSR in peripheral blood PMNs are still not reported. In this study, we collected rat peripheral blood PMNs to observe the relationship between CaSR and PMNs. From the results, we found first that the CaSR protein was expressed in PMNs, and it increased after PMNs were activated with fMLP. In addition, CaSR activator cincalcet promoted the expression of CaSR and P-p65 (NF-κB signaling pathway protein) and Bcl-xl (antiapoptosis protein), and it increased the secretion of interleukin-6 (IL-6) and myeloperoxidase (MPO); meanwhile, it decreased proapoptosis protein Bax expression and the production of IL-10 and reactive oxygen species (ROS). At the same time, cincalcet also decreased the PMN apoptosis rate analyzed by flow cytometry. However, CaSR inhibitor NPS-2143 and NF-κB signaling pathway inhibitor PDTC reverse the results cited earlier. All of these results indicated that CaSR can regulate PMN functions and status to play a role in inflammation, which is probably through the NF-κB signaling pathway.

11β-HSD1 suppresses cardiac fibroblast CXCL2, CXCL5 and neutrophil recruitment to the heart post MI

We have previously demonstrated that neutrophil recruitment to the heart following myocardial infarction (MI) is enhanced in mice lacking 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) that regenerates active glucocorticoid within cells from intrinsically inert metabolites. The present study aimed to identify the mechanism of regulation. In a mouse model of MI, neutrophil mobilization to blood and recruitment to the heart were higher in 11β-HSD1-deficient (Hsd11b1^-/- ) relative to wild-type (WT) mice, despite similar initial injury and circulating glucocorticoid. In bone marrow chimeric mice, neutrophil mobilization was increased when 11β-HSD1 was absent from host cells, but not when absent from donor bone marrow-derived cells. Consistent with a role for 11β-HSD1 in 'host' myocardium, gene expression of a subset of neutrophil chemoattractants, including the chemokines Cxcl2 and Cxcl5, was selectively increased in the myocardium of Hsd11b1^-/- mice relative to WT. SM22α-Cre directed disruption of Hsd11b1 in smooth muscle and cardiomyocytes had no effect on neutrophil recruitment. Expression of Cxcl2 and Cxcl5 was elevated in fibroblast fractions isolated from hearts of Hsd11b1^-/- mice post MI and provision of either corticosterone or of the 11β-HSD1 substrate, 11-dehydrocorticosterone, to cultured murine cardiac fibroblasts suppressed IL-1α-induced expression of Cxcl2 and Cxcl5 These data identify suppression of CXCL2 and CXCL5 chemoattractant expression by 11β-HSD1 as a novel mechanism with potential for regulation of neutrophil recruitment to the injured myocardium, and cardiac fibroblasts as a key site for intracellular glucocorticoid regeneration during acute inflammation following myocardial injury.

The Biological Basis for Cardiac Repair After Myocardial Infarction: From Inflammation to Fibrosis

In adult mammals, massive sudden loss of cardiomyocytes after infarction overwhelms the limited regenerative capacity of the myocardium, resulting in the formation of a collagen-based scar. Necrotic cells release danger signals, activating innate immune pathways and triggering an intense inflammatory response. Stimulation of toll-like receptor signaling and complement activation induces expression of proinflammatory cytokines (such as interleukin-1 and tumor necrosis factor-α) and chemokines (such as monocyte chemoattractant protein-1/ chemokine (C-C motif) ligand 2 [CCL2]). Inflammatory signals promote adhesive interactions between leukocytes and endothelial cells, leading to extravasation of neutrophils and monocytes. As infiltrating leukocytes clear the infarct from dead cells, mediators repressing inflammation are released, and anti-inflammatory mononuclear cell subsets predominate. Suppression of the inflammatory response is associated with activation of reparative cells. Fibroblasts proliferate, undergo myofibroblast transdifferentiation, and deposit large amounts of extracellular matrix proteins maintaining the structural integrity of the infarcted ventricle. The renin-angiotensin-aldosterone system and members of the transforming growth factor-β family play an important role in activation of infarct myofibroblasts. Maturation of the scar follows, as a network of cross-linked collagenous matrix is formed and granulation tissue cells become apoptotic. This review discusses the cellular effectors and molecular signals regulating the inflammatory and reparative response after myocardial infarction. Dysregulation of immune pathways, impaired suppression of postinfarction inflammation, perturbed spatial containment of the inflammatory response, and overactive fibrosis may cause adverse remodeling in patients with infarction contributing to the pathogenesis of heart failure. Therapeutic modulation of the inflammatory and reparative response may hold promise for the prevention of postinfarction heart failure.

Effects of a novel ascorbate-based protocol on infarct size and ventricle function in acute myocardial infarction patients undergoing percutaneous coronary angioplasty

INTRODUCTION

This study was designed to test the hypothesis that high-dose ascorbate prior to reperfusion followed by low chronic oral doses ameliorate myocardial reperfusion injury (MRI) in acute myocardial infarction patients subjected to primary percutaneous coronary angioplasty (PCA).

MATERIAL AND METHODS

A randomized double-blind placebo-controlled and multicenter clinical trial was performed on acute myocardial infarction (AMI) patients who underwent PCA. Sodium ascorbate (320 mmol/l, n = 53) or placebo (n = 46) was infused 30 min prior to PCA. Blood samples were drawn at enrolment (M1), after balloon deflation (M2), 6-8 h after M2 (M3) and at discharge (M4). Total antioxidant capacity of plasma (ferric reducing ability of plasma - FRAP), erythrocyte reduced glutathione (GSH) and plasma ascorbate levels were determined in blood samples. Cardiac magnetic resonance (CMR) was performed at 7-15 days and 2-3 months following PCA. Ninety-nine patients were enrolled. In 67 patients, the first CMR was performed, and 40 patients completed follow-up.

RESULTS

The ascorbate group showed significantly higher ascorbate and FRAP levels and a decrease in the GSH levels at M2 and M3 (p < 0.05). There were no significant differences in the infarct size, indexed end-systolic volume and ejection fraction at both CMRs. There was a significant amelioration in the decreased ejection fraction between the first and second CMR in the ascorbate group (p < 0.05).

CONCLUSIONS

Ascorbate given prior to reperfusion did not show a significant difference in infarct size or ejection fraction. However, it improved the change in ejection fraction determined between 7-15 days and 2-3 months. This result hints at a possible functional effect of ascorbate to ameliorate MRI.

Targeting TRAF3IP2 by Genetic and Interventional Approaches Inhibits Ischemia/Reperfusion-induced Myocardial Injury and Adverse Remodeling

Re-establishing blood supply is the primary goal for reducing myocardial injury in subjects with ischemic heart disease. Paradoxically, reperfusion results in nitroxidative stress and a marked inflammatory response in the heart. TRAF3IP2 (TRAF3 Interacting Protein 2; previously known as CIKS or Act1) is an oxidative stress-responsive cytoplasmic adapter molecule that is an upstream regulator of both IκB kinase (IKK) and c-Jun N-terminal kinase (JNK), and an important mediator of autoimmune and inflammatory responses. Here we investigated the role of TRAF3IP2 in ischemia/reperfusion (I/R)-induced nitroxidative stress, inflammation, myocardial dysfunction, injury, and adverse remodeling. Our data show that I/R up-regulates TRAF3IP2 expression in the heart, and its gene deletion, in a conditional cardiomyocyte-specific manner, significantly attenuates I/R-induced nitroxidative stress, IKK/NF-κB and JNK/AP-1 activation, inflammatory cytokine, chemokine, and adhesion molecule expression, immune cell infiltration, myocardial injury, and contractile dysfunction. Furthermore, Traf3ip2 gene deletion blunts adverse remodeling 12 weeks post-I/R, as evidenced by reduced hypertrophy, fibrosis, and contractile dysfunction. Supporting the genetic approach, an interventional approach using ultrasound-targeted microbubble destruction-mediated delivery of phosphorothioated TRAF3IP2 antisense oligonucleotides into the LV in a clinically relevant time frame significantly inhibits TRAF3IP2 expression and myocardial injury in wild type mice post-I/R. Furthermore, ameliorating myocardial damage by targeting TRAF3IP2 appears to be more effective to inhibiting its downstream signaling intermediates NF-κB and JNK. Therefore, TRAF3IP2 could be a potential therapeutic target in ischemic heart disease.

Piperine Ameliorates Lipopolysaccharide-Induced Acute Lung Injury via Modulating NF-κB Signaling Pathways

Piperine, one of the active components of black pepper, has been reported to have antioxidant and anti-inflammatory activities. However, the effects of piperine on lipolysaccharide (LPS)-induced acute lung injury (ALI) have not been reported. Thus, the protective effects of piperine against LPS-induced ALI were investigated in this study. LPS-induced lung injury was assessed by histological study, myeloperoxidase (MPO) activity, and inflammatory cytokine production. Our results demonstrated that piperine attenuated LPS-induced MPO activity, lung edema, and inflammatory cytokines TNF-α, IL-6, and IL-1β production. Histological studies showed that piperine obviously attenuated LPS-induced lung injury. In addition, piperine significantly inhibited LPS-induced NF-κB activation. In conclusion, our results demonstrated that piperine had a protective effect on LPS-induced ALI. The anti-inflammatory mechanism of piperine is through inhibition of NF-κB activation. Piperine may be a potential therapeutic agent for ALI.

CARD9 as a potential target in cardiovascular disease

Systemic inflammation and localized macrophage infiltration have been implicated in cardiovascular pathologies, including coronary artery disease, carotid atherosclerosis, heart failure, obesity-associated heart dysfunction, and cardiac fibrosis. Inflammation induces macrophage infiltration and activation and release of cytokines and chemokines, causing tissue dysfunction by instigating a positive feedback loop that further propagates inflammation. Cytosolic adaptor caspase recruitment domain family, member 9 (CARD9) is a protein expressed primarily by dendritic cells, neutrophils, and macrophages, in which it mediates cytokine secretion. The purpose of this review is to highlight the role of CARD9 as a potential target in inflammation-related cardiovascular pathologies.

Heart-resident CCR2+ macrophages promote neutrophil extravasation through TLR9/MyD88/CXCL5 signaling

It is well established that maladaptive innate immune responses to sterile tissue injury represent a fundamental mechanism of disease pathogenesis. In the context of cardiac ischemia reperfusion injury, neutrophils enter inflamed heart tissue, where they play an important role in potentiating tissue damage and contributing to contractile dysfunction. The precise mechanisms that govern how neutrophils are recruited to and enter the injured heart are incompletely understood. Using a model of cardiac transplant-mediated ischemia reperfusion injury and intravital 2-photon imaging of beating mouse hearts, we determined that tissue-resident CCR2⁺ monocyte-derived macrophages are essential mediators of neutrophil recruitment into ischemic myocardial tissue. Our studies revealed that neutrophil extravasation is mediated by a TLR9/MyD88/CXCL5 pathway. Intravital 2-photon imaging demonstrated that CXCL2 and CXCL5 play critical and nonredundant roles in guiding neutrophil adhesion and crawling, respectively. Together, these findings uncover a specific role for a tissue-resident monocyte-derived macrophage subset in sterile tissue inflammation and support the evolving concept that macrophage ontogeny is an important determinant of function. Furthermore, our results provide the framework for targeting of cell-specific signaling pathways in myocardial ischemia reperfusion injury.

Leukocyte-Expressed β2-Adrenergic Receptors Are Essential for Survival After Acute Myocardial Injury

BACKGROUND

Immune cell-mediated inflammation is an essential process for mounting a repair response after myocardial infarction (MI). The sympathetic nervous system is known to regulate immune system function through β-adrenergic receptors (βARs); however, their role in regulating immune cell responses to acute cardiac injury is unknown.

METHODS

Wild-type (WT) mice were irradiated followed by isoform-specific βAR knockout (βARKO) or WT bone-marrow transplantation (BMT) and after full reconstitution underwent MI surgery. Survival was monitored over time, and alterations in immune cell infiltration after MI were examined through immunohistochemistry. Alterations in splenic function were identified through the investigation of altered adhesion receptor expression.

RESULTS

β2ARKO BMT mice displayed 100% mortality resulting from cardiac rupture within 12 days after MI compared with ≈20% mortality in WT BMT mice. β2ARKO BMT mice displayed severely reduced post-MI cardiac infiltration of leukocytes with reciprocally enhanced splenic retention of the same immune cell populations. Splenic retention of the leukocytes was associated with an increase in vascular cell adhesion molecule-1 expression, which itself was regulated via β-arrestin-dependent β2AR signaling. Furthermore, vascular cell adhesion molecule-1 expression in both mouse and human macrophages was sensitive to β2AR activity, and spleens from human tissue donors treated with β-blocker showed enhanced vascular cell adhesion molecule-1 expression. The impairments in splenic retention and cardiac infiltration of leukocytes after MI were restored to WT levels via lentiviral-mediated re-expression of β2AR in β2ARKO bone marrow before transplantation, which also resulted in post-MI survival rates comparable to those in WT BMT mice.

CONCLUSIONS

Immune cell-expressed β2AR plays an essential role in regulating the early inflammatory repair response to acute myocardial injury by facilitating cardiac leukocyte infiltration.

Chemokines and Heart Disease: A Network Connecting Cardiovascular Biology to Immune and Autonomic Nervous Systems

Among the chemokines discovered to date, nineteen are presently considered to be relevant in heart disease and are involved in all stages of cardiovascular response to injury. Chemokines are interesting as biomarkers to predict risk of cardiovascular events in apparently healthy people and as possible therapeutic targets. Moreover, they could have a role as mediators of crosstalk between immune and cardiovascular system, since they seem to act as a “working-network” in deep linkage with the autonomic nervous system. In this paper we will describe the single chemokines more involved in heart diseases; then we will present a comprehensive perspective of them as a complex network connecting the cardiovascular system to both the immune and the autonomic nervous systems. Finally, some recent evidences indicating chemokines as a possible new tool to predict cardiovascular risk will be described.

The enduring importance of animal models in understanding periodontal disease

Whereas no single animal model can reproduce the complexity of periodontitis, different aspects of the disease can be addressed by distinct models. Despite their limitations, animal models are essential for testing the biological significance of in vitro findings and for establishing cause-and-effect relationships relevant to clinical observations, which are typically correlative. We provide evidence that animal-based studies have generated a durable framework for dissecting the mechanistic basis of periodontitis. These studies have solidified the etiologic role of bacteria in initiating the inflammatory response that leads to periodontal bone loss and have identified key mediators (IL-1, TNF, prostaglandins, complement, RANKL) that induce inflammatory breakdown. Moreover, animal studies suggest that dysbiosis, rather than individual bacterial species, are important in initiating periodontal bone loss and have introduced the concept that organisms previously considered commensals can play important roles as accessory pathogens or pathobionts. These studies have also provided insight as to how systemic conditions, such as diabetes or leukocyte adhesion deficiency, contribute to tissue destruction. In addition, animal studies have identified and been useful in testing therapeutic targets.

Inflammation as a therapeutic target in myocardial infarction: learning from past failures to meet future challenges

In the infarcted myocardium, necrotic cardiomyocytes release danger signals, activating an intense inflammatory response. Inflammatory pathways play a crucial role in regulation of a wide range of cellular processes involved in injury, repair, and remodeling of the infarcted heart. Proinflammatory cytokines, such as tumor necrosis factor α and interleukin 1, are markedly upregulated in the infarcted myocardium and promote adhesive interactions between endothelial cells and leukocytes by stimulating chemokine and adhesion molecule expression. Distinct pairs of chemokines and chemokine receptors are implicated in recruitment of various leukocyte subpopulations in the infarcted myocardium. For more than the past 30 years, extensive experimental work has explored the role of inflammatory signals and the contributions of leukocyte subpopulations in myocardial infarction. Robust evidence derived from experimental models of myocardial infarction has identified inflammatory targets that may attenuate cardiomyocyte injury or protect from adverse remodeling. Unfortunately, attempts to translate the promising experimental findings to clinical therapy have failed. This review article discusses the biology of the inflammatory response after myocardial infarction, attempts to identify the causes for the translational failures of the past, and proposes promising new therapeutic directions. Because of their potential involvement in injurious, reparative, and regenerative responses, inflammatory cells may hold the key for design of new therapies in myocardial infarction.

Progesterone protects endothelial cells after cerebrovascular occlusion by decreasing MCP-1- and CXCL1-mediated macrophage infiltration

The neuroprotective effects of progesterone after ischemic stroke have been established, but the role of progesterone in promoting cerebrovascular repair remains under-explored. Male Sprague-Dawley rats underwent transient middle cerebral artery occlusion (tMCAO) for 90 min followed by reperfusion for 3 days. Progesterone (8 mg/kg/day) was administered intraperitoneally at 1h after initial occlusion followed by subcutaneous injections at 6, 24 and 48 h post-occlusion. Rats were euthanized after 72 h and brain endothelial cell density and macrophage infiltration were evaluated within the cerebral cortex. We also assessed progesterone's ability to induce macrophage migration toward hypoxic/reoxygenated cultured endothelial cells. We found that progesterone treatment post-tMCAO protects ischemic endothelial cells from macrophage infiltration. We further demonstrate that infiltration of monocytes/macrophages can be induced by potent chemotactic factors such as monocyte chemoattractant protein-1 (MCP-1) and the chemokine ligand 1 (CXCL1), secreted by hypoxic/reoxygenated endothelial cells. Progesterone blunts secretion of MCP-1 and CXCL1 from endothelial cells after hypoxia/reoxygenation injury and decreases leukocyte infiltration. The treatment protects ischemic endothelial cells from macrophage infiltration and thus preserves vascularization after ischemic injury.

Resveratrol attenuates inflammation in the rat heart subjected to ischemia-reperfusion: Role of the TLR4/NF-κB signaling pathway

It has been previously reported that Toll‑like receptor 4 (TLR4)/NF‑κB signaling mediates early inflammation during myocardial ischemia and reperfusion. It has additionally been suggested that resveratrol produces cardioprotective and anti‑inflammatory effects. The aim of the present study was to investigate whether resveratrol could modulate TLR4/NF‑κB signaling, reduce neutrophil accumulation and TNF‑α induction in an ischemia/reperfusion injured rat heart model. Rats were randomly exposed to a sham operation, myocardial ischemia and reperfusion (MI/R), MI/R + resveratrol or MI/R + resveratrol + L‑NAME. The data showed that following MI/R, the expression of myocardial TLR4 and NF‑κB increased significantly in the area of induced ischemia. As compared with MI/R, resveratrol significantly attenuated the expression of TLR4 and NF‑κB and reduced the levels of myeloperoxidase, serum and myocardial TNF‑α production, myocardial infarct size and myocardial apoptosis induced by MI/R. All the effects of resveratrol were abolished upon application of L‑NAME, a nitric oxide (NO) synthase inhibitor. These data provide evidence that resveratrol inhibits TLR4/NF‑κB signaling in the rat heart subjected to MI/R, and the anti‑inflammatory effect of resveratrol is associated with NO production.

Pterostilbene attenuates the inflammatory reaction induced by ischemia/reperfusion in rat heart

The role of pterostilbene (Pte) in inflammation induced by ischemia/reperfusion is not well understood. The aim of this study was to investigate whether Pte modulates neutrophil accumulation and the induction of tumor necrosis factor-α (TNF-α) in an ischemia/reperfusion (I/R)-injured rat heart model. Rats were randomly exposed to a sham operation, myocardial ischemia/reperfusion (MI/R) alone, MI/R+Pte, MI/R+Pte+L-NAME and MI/R+Pte+ (methylene blue) MB. The results demonstrated that compared with MI/R, Pte reduced the area of myocardial infarction, the levels of myocardial myeloperoxidase, serum creatinine kinase and lactate dehydrogenase, and the production of serum and myocardial TNF-α. These Pte-induced effects were eliminated by the administration of L-NAME, a nitric oxide (NO) synthase inhibitor, and MB, a cyclic guanosine monophosphate (cGMP) inhibitor. In conclusion, Pte produces cardioprotective and anti-inflammatory effects. These effects may be associated with an increase in NO production, the inhibition of neutrophil accumulation, and induction of TNF-α and cGMP signaling pathways in myocardium subjected to MI/R.

Etanercept attenuates myocardial ischemia/reperfusion injury by decreasing inflammation and oxidative stress

The protective role of etanercept in myocardial ischemia/reperfusion is not well understood. The aim of this study was to investigate whether etanercept modulates neutrophil accumulation, TNF-α induction and oxidative stress in an ischemia/reperfusion injured rat heart model. Rats were randomly exposed to sham operation, myocardial ischemia/reperfusion (MI/R) alone, MI/R+ etanercept. The results demonstrated that compared to MI/R, etanercept reduced myocardial infarction area, myocardial myeloperoxidase (MPO) levels, serum creatinine kinase (CK) and lactate dehydrogenase (LDH) levels, and both serum and myocardial TNF-α production. Etanercept also markedly enhanced the activities of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), and reduced the level of malondialdehyde (MDA) in MI/R rats. In summary, our data suggested that etanercept has protective effects against MI/R injury in rats, which may be attributed to attenuating inflammation and oxidative stress.

Regulatory T cells are recruited in the infarcted mouse myocardium and may modulate fibroblast phenotype and function

Regulatory T cells (Tregs) play a pivotal role in suppressing immune responses regulating behavior and gene expression in effector T cells, macrophages, and dendritic cells. Tregs infiltrate the infarcted myocardium; however, their role the inflammatory and reparative response after myocardial infarction remains poorly understood. We used FoxP3(EGFP) reporter mice to study Treg trafficking in the infarcted heart and examined the effects of Treg depletion on postinfarction remodeling using an anti-CD25 antibody. Moreover, we investigated the in vitro effects of Tregs on cardiac fibroblast phenotype and function. Low numbers of Tregs infiltrated the infarcted myocardium after 24-72 h of reperfusion. Treg depletion had no significant effects on cardiac dysfunction and scar size after reperfused myocardial infarction but accelerated ventricular dilation and accentuated apical remodeling. Enhanced myocardial dilation in Treg-depleted animals was associated with increased expression of chemokine (C-C motif) ligand 2 and accentuated macrophage infiltration. In vitro, Tregs modulated the cardiac fibroblast phenotype, reducing expression of α-smooth muscle actin, decreasing expression of matrix metalloproteinase-3, and attenuating contraction of fibroblast-populated collagen pads. Our findings suggest that endogenous Tregs have modest effects on the inflammatory and reparative response after myocardial infarction. However, the anti-inflammatory and matrix-preserving properties of Tregs may suggest a role for Treg-based cell therapy in the attenuation of adverse postinfarction remodeling.

CXCR3-independent actions of the CXC chemokine CXCL10 in the infarcted myocardium and in isolated cardiac fibroblasts are mediated through proteoglycans

AIMS

The CXC chemokine CXCL10 is up-regulated in the infarcted myocardium and limits cardiac fibrosis by inhibiting growth factor-mediated fibroblast migration. CXCL10 signals by binding to its receptor CXCR3; however, recently CXCR3-independent CXCL10 actions have been suggested. Our study explores the role of CXCR3 signalling in myocardial infarction and investigates its involvement in mediating the anti-fibrotic effects of CXCL10.

METHODS AND RESULTS

Wild-type and CXCR3 null mice underwent reperfused infarction protocols. CXCL10 was markedly induced in the infarct; in contrast, expression of the other two CXCR3 ligands, CXCL9 and CXCL11 was extremely low. CXCR3 loss did not affect scar size, geometric ventricular remodelling, collagen deposition, and systolic dysfunction of the infarcted heart. CXCR3 null mice had increased peak neutrophil recruitment and delayed myofibroblast infiltration in the infarcted heart, but exhibited comparable myocardial expression of pro-inflammatory cytokines and chemokines. In vitro, CXCL10 did not modulate Transforming Growth Factor (TGF)-β signalling, but inhibited basic fibroblast growth factor (bFGF)-induced cardiac fibroblast migration in both wild-type and CXCR3 null cells. Treatment of fibroblasts with heparinase and chondroitinase to cleave glycosaminoglycan chains abrogated the inhibitory effects of CXCL10 on cell migration.

CONCLUSION

CXCR3 signalling does not critically regulate cardiac remodelling and dysfunction following myocardial infarction. The anti-fibrotic effects of CXCL10 in the healing infarct and in isolated cardiac fibroblasts are CXCR3-independent and may be mediated through proteoglycan signalling. Thus, administration of CXCR3-defective forms of CXCL10 may be an effective anti-fibrotic strategy in the remodelling myocardium without activating a potentially injurious, CXCR3-driven T cell response.

The inflammatory response in myocardial injury, repair, and remodelling

Myocardial infarction triggers an intense inflammatory response that is essential for cardiac repair, but which is also implicated in the pathogenesis of postinfarction remodelling and heart failure. Signals in the infarcted myocardium activate toll-like receptor signalling, while complement activation and generation of reactive oxygen species induce cytokine and chemokine upregulation. Leukocytes recruited to the infarcted area, remove dead cells and matrix debris by phagocytosis, while preparing the area for scar formation. Timely repression of the inflammatory response is critical for effective healing, and is followed by activation of myofibroblasts that secrete matrix proteins in the infarcted area. Members of the transforming growth factor β family are critically involved in suppression of inflammation and activation of a profibrotic programme. Translation of these concepts to the clinic requires an understanding of the pathophysiological complexity and heterogeneity of postinfarction remodelling in patients with myocardial infarction. Individuals with an overactive and prolonged postinfarction inflammatory response might exhibit left ventricular dilatation and systolic dysfunction and might benefit from targeted anti-IL-1 or anti-chemokine therapies, whereas patients with an exaggerated fibrogenic reaction can develop heart failure with preserved ejection fraction and might require inhibition of the Smad3 (mothers against decapentaplegic homolog 3) cascade. Biomarker-based approaches are needed to identify patients with distinct pathophysiologic responses and to rationally implement inflammation-modulating strategies.

Induction of chemokines and cytokines before neutrophils and macrophage recruitment in different regions of rat liver after TAA administration

Single-dose thioacetamide (TAA) administration induces inflammation and acute liver damage. The mechanism of inflammatory cell recruitment in the liver is still unclear. The aim of this study was to examine the sequence and recruitment of inflammatory cells in different liver regions in relation to CXC- and CC-chemokine and cytokine expression during acute liver injury. Single-dose TAA was administered to rats intraperitoneally, and animals were killed at different time points thereafter. Serum and liver tissue were taken and frozen immediately. Tissue was used for immunostaining cryostat sections, RNA, and protein extraction. RT-PCR and western blotting were performed for RNA and protein analysis, respectively. An early increase (3 h) in CXCL8/IL-8 levels was measured followed by a marked release in MCP1/CCL2 (24 h) serum levels after TAA administration compared with controls. Similarly, an early increase in specific RNA of hepatic chemokines CXCL1/KC and CXCL8/IL-8 was found at 3 h, followed by an upregulation of CXCL5/LIX (6 h), CXCL2/MIP-2 (12 h), and MCP1/CCL2 gene expression at 24-48 h. Further, an induction of pro-inflammatory cytokines IFN-γ and IL-1β followed by IL-6 and TNF-α was observed with a maximum at 12 h. The magnitude of increase in gene expression of TNF-α and MCP1/CCL2 was the highest among all cytokines and chemokines, respectively. By means of immunohistochemistry, an early (12-24 h) increase in the number of only neutrophil granulocytes (NGs) attached to and around portal vessel walls was observed, followed by increased numbers of mononuclear phagocytes (24-48 h) along the sinusoids. Treatment of the human monocytic cell line U-937 with TNF-α increased the gene expression of CXCL1/KC, CXCL8/IL-8, and MCP1/CCL2. Conversely, adding of infliximab (IFX) to the culture medium inhibited this upregulation significantly. In conclusion, single-dose TAA administration induces a sequence of events with a defined upregulation of gene expression of inflammatory chemokines and cytokines and a transient accumulation of NGs within the portal area and macrophages along the sinusoids throughout the liver. Periportal inflammation seems to precede hepatocellular damage.

Electronegative low-density lipoprotein induces cardiomyocyte apoptosis indirectly through endothelial cell-released chemokines

Cardiomyocyte apoptosis has a critical role in the pathogenesis of heart failure. L5, the most negatively charged subfraction of human plasma low-density lipoprotein (LDL), induces several atherogenic responses in endothelial cells (ECs), including apoptosis. We hypothesized that L5 also contributes to cardiomyocyte apoptosis and studied whether it does so indirectly by inducing the secretion of factors from ECs. We examined apoptosis of rat cardiomyocytes treated with culture-conditioned medium (CCM) of rat ECs that were exposed to L5 or L1 (the least negatively charged LDL subfraction). Apoptosis at early and late time points was twofold greater in cardiomyocytes treated with L5 CCM than in those treated with L1 CCM. The indirect effect of L5 on cardiomyocyte apoptosis was significantly reduced by pretreating ECs with inhibitors of phosphatidylinositol 3-kinase (PI3K) or CXC receptor 2 (CXCR2). Studies with cytokine protein arrays revealed that L5 CCM, but not L1 CCM, contained high levels of ELR(+) CXC chemokines, including lipopolysaccharide-induced chemokine (LIX) and interleukin (IL)-8. The L5-induced release of these chemokines from ECs was abolished by inhibiting the lectin-like oxidized LDL receptor-1 (LOX-1). Addition of recombinant LIX or IL-8 to CCM-free cardiomyocyte cultures increased apoptosis and enhanced production of tumor necrosis factor (TNF)-α and IL-1β by increasing the translocation of NF-κB into the nucleus; these effects were attenuated by inhibiting PI3K and CXCR2. In conclusion, L5 may indirectly induce cardiomyocyte apoptosis by enhancing secretion of ELR(+) CXC chemokines from ECs, which in turn activate CXCR2/PI3K/NF-κB signaling to increase the release of TNF-α and IL-1β.

Adiponectin inhibits oxidative/nitrative stress during myocardial ischemia and reperfusion via PKA signaling

The cardioprotective effects of adiponectin (APN) against myocardial ischemia/reperfusion (MI/R) injury are well known. However, comprehension of the mechanisms mediating intracellular APN signaling remains incomplete. We recently demonstrate the antioxidant/antinitrative effects of APN are not dependent on AMPK. Protein kinase A (PKA) has been previously shown to be activated by APN, with uncertain relevance to APN cardiac protection. The current study determined whether the antioxidative/antinitrative effect of APN is mediated by PKA. Administration of APN (2 μg/g) 10 min before reperfusion significantly enhanced cardiac PKA activity, reduced oxidative stress, and decreased infarct size. Knockdown of cardiac PKA expression (PKA-KD) by intramyocardial injection of PKA-siRNAs (>70% suppression) significantly inhibited APN cardioprotection determined by cardiac apoptosis, infarct size, and cardiac function. Moreover, PKA-KD virtually abolished the suppressive effect of APN on MI/R-induced NADPH oxidase overexpression and superoxide overproduction and partially inhibited the effect of APN on nitrative protein modification in MI/R heart. Mechanistically, APN significantly inhibited MI/R-induced IKK/IκB phosphorylation and NF-κB activation, which were blocked in PKA-KD heart. Finally, the PKA-mediated antioxidant/antinitrative and cardioprotective effects of APN are intact in AMPK-deficient mice, suggesting that there is no cross talk between AMPK and PKA signaling in APN cardioprotection. Collectively, we demonstrate for the first time that APN inhibits oxidative/nitrative stress during MI/R via PKA-dependent NF-κB inhibition.