[Oral administration of TRPV4 inhibitor improves atrial calcium handling abnormalities in sterile pericarditis rats].

Atrial Ca2+ handling abnormalities, mainly involving the dysfunction of ryanodine receptor (RyR) and sarcoplasmic reticulum Ca2+-ATPase (SERCA), play a role in the pathogenesis of atrial fibrillation (AF). Previously, we found that the expression and function of transient receptor potential vanilloid subtype 4 (TRPV4) are upregulated in a sterile pericarditis (SP) rat model of AF, and oral administration of TRPV4 inhibitor GSK2193874 alleviates AF in this animal model. The aim of this study was to investigate whether oral administration of GSK2193874 could alleviate atrial Ca2+ handling abnormalities in SP rats. A SP rat model of AF was established by daubing sterile talcum powder on both atria of Sprague-Dawley (SD) rats after a pericardiotomy, to simulate the pathogenesis of postoperative atrial fibrillation (POAF). On the 3rd postoperative day, Ca2+ signals of atria were collected in isolated perfused hearts by optical mapping. Ca2+ transient duration (CaD), alternan, and the recovery properties of Ca2+ transient (CaT) were quantified and analyzed. GSK2193874 treatment reversed the abnormal prolongation of time to peak (determined mainly by RyR activity) and CaD (determined mainly by SERCA activity), as well as the regional heterogeneity of CaD in SP rats. Furthermore, GSK2193874 treatment relieved alternan in SP rats, and reduced its incidence of discordant alternan (DIS-ALT). More importantly, GSK2193874 treatment prevented the reduction of the S2/S1 CaT ratio (determined mainly by RyR refractoriness) in SP rats, and decreased its regional heterogeneity. Taken together, oral administration of TRPV4 inhibitor alleviates Ca2+ handling abnormalities in SP rats primarily by blocking the TRPV4-Ca2+-RyR pathway, and thus exerts therapeutic effect on POAF.

Blockage of transient receptor potential vanilloid 4 prevents postoperative atrial fibrillation by inhibiting NLRP3-inflammasome in sterile pericarditis mice.

The incidence of atrial fibrillation (AF) increases after surgery and is associated with the activation of NLRP3-inflammation. Our previous studies have found that transient receptor potential vanilloid 4 (TRPV4) blockade reduces the susceptibility to AF, but its molecular mechanisms remains unclear. Therefore, we hypothesized that blockage of TRPV4 reduces the incidence of AF by inhibiting NLRP3-inflammasome in sterile pericarditis (SP) mice. In this study, we established SP mice by dusting talcum powder on atrial surfaces. We first confirmed that genetic or pharmacological TRPV4 inhibition reduced the susceptibility to AF in SP mice. We also found that the expression level of NLRP3-inflammasome and inflammatory cytokines significantly increased in the atria of SP mice, which further increased in application the TRPV4 agonist GSK1016790A (GSK101) and decreased in application the TRPV4 antagonist GSK2193874. More importantly, ERK inhibitor (U0126) or NF-κB inhibitor (Bay11-7082) could partially reverse GSK101-induced NLRP3-inflammasome up-regulation. Interestingly, U0126 can reversed GSK101-induced NF-κB phosphorylation, but Bay11-7082 cannot change GSK101-induced ERK phosphorylation. Finally, we shown that the activation of NLRP3-inflammasome and ERK/NF-κB signaling pathway significantly reduced in TRPV4-knockout SP mice. Collectively, our studies indicate that blockage of TRPV4 prevents AF in SP mice by inhibiting NLRP3-inflammasome through the ERK/NF-κB signaling pathway.

LXR-Mediated Regulation of Marine-Derived Piericidins Aggravates High-Cholesterol Diet-Induced Cholesterol Metabolism Disorder in Mice.

Reported as two antirenal cell carcinoma (RCC) drug candidates, marine-derived compounds piericidin A (PA) and glucopiericidin A (GPA) exhibit hepatotoxicity in renal carcinoma xenograft mice. Proteomics and transcriptomics reveal the hepatotoxicity related with cholesterol disposition since RCC is characterized by cholesterol accumulation. PA/GPA aggravate hepatotoxicity in high-cholesterol diet (HCD)-fed mice while exhibiting no toxicity in chow diet-fed mice. High cholesterol accumulation in liver is liver X receptor (LXR)-mediated cytochrome P450 family 7 subfamily a member 1 (CYP7A1) depression and low-density lipoprotein receptor (LDLR) activation. The farnesoid X nuclear receptor (FXR) is also depressed with a downregulated target gene OSTα. Different from PA directly combined with LXRα as an inhibitor, GPA exists as a prodrug in the liver and exerts toxic effects due to transformation into PA. Surface plasmon resonance (SPR) and docking results of 17 piericidins illustrate that glycosides exert no LXRα binding activity. A longer survival time of GPA-treated mice indicates that further exploration in anti-RCC drug research should focus on reducing glycosides transformed into PA and concentrating in the kidney tumor rather than the liver for lowering the risk of hepatotoxicity.

The autoinflammatory side of recurrent pericarditis: Enlightening the pathogenesis for a more rational treatment.

Recurrent pericarditis (RP) is a troublesome and debilitating complication of acute pericarditis. Although the etiopathogenesis of this condition remains unknown, an intricate overlap of autoimmune and autoinflammatory pathways has been hypothesized to explain its beginning and recurrence over time. The majority of cases are defined as "idiopathic", reflecting our awkwardness to unravel the intimate mechanisms of RP. Given the possible occurrence of anti-nuclear, anti-heart and anti-intercalated disk antibodies as well as the association with peculiar human leukocyte antigen haplotypes, an autoimmune contribution has been claimed to specify the nature of RP. However, the most innovative pathogenic scenario of RP has been conferred to the innate immune system, mainly involving neutrophils and macrophages that produce a large amount of interleukin (IL)-1 via inflammasome activation. The clinical resemblance of RP with autoinflammatory diseases that may be marked by symptomatic serositis, high fevers and strikingly increased inflammatory parameters further suggests a similar inflammasome-mediated pathogenesis. Aspirin or non-steroidal anti-inflammatory drugs (NSAIDs) remain the mainstay of therapy in RP, whereas colchicine is recommended on top of standard anti-inflammatory therapy, due to its role in inhibiting the IL-1 converting enzyme (caspase 1) within the inflammasome as well as the release of additional pro-inflammatory mediators and reactive oxygen species. With regard to treatment of RP refractory to NSAIDs and colchicine, blockade of IL-1 is the most relevant advance achieved in the last decade: the outstanding effect of the short-acting IL-1 receptor antagonist anakinra has been first recognized in the pediatric population, giving a proof of its practical feasibility. Over a more recent time, a growing experience with anakinra deriving from both large and small studies has further confirmed that RP might be regarded as an IL-1-mediated disease. This review aims to provide a contemporary insight into the mechanisms leading to RP as well as into the most recent literature data showing the beneficial approach originating from IL-1 blockade in this intriguing disorder.

TRPV4 blockade suppresses atrial fibrillation in sterile pericarditis rats.

Atrial fibrillation (AF) commonly occurs after surgery and is associated with atrial remodeling. TRPV4 is functionally expressed in the heart, and its activation affects cardiac structure and functions. We hypothesized that TRPV4 blockade alleviates atrial remodeling and reduces AF induction in sterile pericarditis (SP) rats. TRPV4 antagonist GSK2193874 or vehicle was orally administered 1 day before pericardiotomy. AF susceptibility and atrial function were assessed using in vivo electrophysiology, ex vivo optical mapping, patch clamp, and molecular biology on day 3 after surgery. TRPV4 expression increased in the atria of SP rats and patients with AF. GSK2193874 significantly reduced AF vulnerability in vivo and the frequency of atrial ectopy and AF with a reentrant pattern ex vivo. Mechanistically, GSK2193874 reversed the abnormal action potential duration (APD) prolongation in atrial myocytes through the regulation of voltage-gated K+ currents (IK); reduced the activation of atrial fibroblasts by inhibiting P38, AKT, and STAT3 pathways; and alleviated the infiltration of immune cells. Our results reveal that TRPV4 blockade prevented abnormal changes in atrial myocyte electrophysiology and ameliorated atrial fibrosis and inflammation in SP rats; therefore, it might be a promising strategy to treat AF, particularly postoperative AF.

Colchicine prevents atrial fibrillation promotion by inhibiting IL-1ß-induced IL-6 release and atrial fibrosis in the rat sterile pericarditis model.

A few clinical trials have recently reported the potential effect of colchicine in preventing post-operative atrial fibrillation (POAF) and early atrial fibrillation (AF) recurrence after catheter pulmonary vein isolation. However, the molecular mechanisms through which colchicine inhibits AF remain unclear. We aim to assess the anti-AF effect of colchicine in the rat sterile pericarditis (SP) model and to investigate its molecular mechanisms. SP was induced in Sprague-Dawley rats by the epicardial application of sterile talc. Treatment with colchicine or vehicle began 1 d before pericardiotomy. AF was induced by transesophageal burst pacing on day 3 after surgery. Treatment with colchicine reduced the duration of AF and the probability of induction of AF in SP rats. The dose of 0.5 mg kg-1·day-1 had the best effect. Such treatment also reduced neutrophil infiltration, the mRNA expression of IL-6, TGF-ß, and TNF-α, atrial fibrosis, fibrosis related genes, and signal molecules (STAT3, P38, and AKT). Meanwhile, the release of IL-1ß (4-24 h) and IL-6 (4-72 h) in atria after surgery was significantly inhibited by colchicine. In cultured rat cardiac fibroblasts, colchicine treatment inhibited IL-1ß-induced expression of IL-6, which was accompanied by significantly decreased phosphorylation of P38, AKT, JNK, and NFκB. Interestingly, the supplementation of IL-6 abolished the anti-AF effect of colchicine in SP rats. Colchicine prevents AF in SP rats through the inhibition of IL-1ß-induced IL-6 release and subsequent atrial fibrosis. However, further studies are required to investigate whether colchicine inhibits POAF through other mechanisms.

Heart-type fatty acid-binding protein (H-FABP), pentraxin-3 (PTX-3) and thrombomodulin in bovine traumatic pericarditis.

The aim of this study was to evaluate the biomarkers of cardiac damage such as heart-type fatty acid-binding protein (H-FABP), pentraxin-3 (PTX-3), and thrombomodulin (TM) for the detection and prognosis of bovine traumatic pericarditis (TP). Spontaneous TP was diagnosed on the basis of history, clinical signs, complete blood count, glutaraldehyde test, ultrasonography, and pericardiocentesis findings. H-FABP, PTX-3 and TM levels in serum were compared between 25 Holstein cows diagnosed with spontaneous TP and 10 healthy control cows using bovine-specific ELISA kits. Serum H-FABP in cattle with TP was significantly (P < 0.05) higher than in the control group and positively correlated with cardiac troponin-I (cTnI), creatine kinase myocardial band (CK-MB), PTX-3 and TM (r = 0.683, 0.342, 0.448 and 0.424, respectively; P < 0.05). The serum levels of PTX-3 (P < 0.05) and TM (P < 0.05) in cattle with TP were significantly higher than in the control group. Cardiac damage biomarkers H-FABP, PTX-3 and TM may be useful in the diagnosis of bovine TP.

Idiopathic Pericarditis-an Autoinflammatory Disease?

PURPOSE OF THE REVIEW: Idiopathic acute and recurrent pericarditis are rare diseases of unknown origin. Here, we review trigger factors, pathomechanism, and treatment options for acute and recurrent pericarditis. RECENT FINDINGS: Acute pericarditis can be triggered by viral infections, myocardial ischemia, heart catheter interventions, cardiac surgery or seem to occur without any trigger. Earlier reports about viral nucleic acids in the effusion or myocardial autoantibodies in serum were detected only in a minority of patients. The current pathomechanistic concept focuses on the innate immune system. Clinical trials revealed that colchicine and anti-IL1ß-targeted medication were effective to control acute and recurrent attacks. Activation of the innate immune system in pericarditis suggests that autoinflammation contributes to acute and recurrent pericarditis. The efficacy of colchicine and anti-IL1ß-targeted medication in clinical trials indicates that acute and recurrent pericarditis should be regarded as an autoinflammatory disease. Therefore, idiopathic pericarditis should be considered as an autoinflammatory disease.

Inflammation and pericarditis: Are neutrophils actors behind the scenes?

The morbidity of acute pericarditis is increasing over time impacting on patient quality of life. Recent clinical trials focused especially on clinical aspects, with a modest interest in pathophysiological mechanisms. This narrative review, based on papers in English language obtained via PubMed up to April 2018, aims at focusing on the role of the innate immunity in pericarditis and discussing future potential therapeutic strategies impacting on disease pathophysiology. In developed countries, most cases of pericarditis are referred to as idiopathic, although etiological causes have been described, with autoreactive/lymphocytic, malignant, and infectious ones as the most frequent causes. Apart the known impairment of the adaptive immunity, recently a large body evidence indicated the central role of the innate immune system in the pathogenesis of recurrent pericarditis, starting from similarities with autoinflammatory diseases. Accordingly, the "inflammasome" has been shown to behave as an important player in pericarditis development. Similarly, the beneficial effect of colchicine in recurrent pericarditis confirms that neutrophils are important effectors as colchicine, which can block neutrophil chemotaxis, interferes with neutrophil adhesion and recruitment to injured tissues and abrogate superoxide production. Anyway, the role of the adaptive immune system in pericarditis cannot be reduced to a black or white issue as mechanisms often overlap. Therefore, we believe that more efficient therapeutic strategies have to be investigated by targeting neutrophil-derived mediators (such as metalloproteinases) and disentangling the strict interplay between neutrophils and platelets. In this view, some progress has been done by using the recombinant human interleukin-1 receptor antagonist anakinra.

Synthetic polymer coatings diminish chronic inflammation risk in large ECM-based materials.

Degradable materials that can support cell infiltration and remodeling are the basis of tissue engineered approaches to vascular repair. In addition, to replace or close a large area of the vasculature, a patch material or scaffold must also withstand high pressure over time. Extracellular matrix-based (ECM-based) scaffolds offer a biological substrate with environmental cues that can support the formation of appropriate vascular tissue. However, scaffolds made from pure natural materials can degrade rapidly, resulting in reduced mechanical integrity of the implant and possible chronic inflammation in the site. A hybrid biomaterial, combining the matrix-dense tissue pericardium with a layer of the degradable polymer poly(propylene fumarate) (PPF), is suited to withstand rapid enzymatic degradation and control the presentation of an unaltered natural tissue matrix for remodeling activity. In this study, we show that the polymer reinforced hybrid supports cellular infiltration, but has fewer macrophages in the vicinity of the implant after 6 weeks in vivo than an untreated tissue control in both athymic and immunocompetent rat models. This result is supported by changes seen in other inflammatory cell populations. Based on significant differences in the inflammatory response to untreated pericardium and PPF-reinforced pericardium, we conclude that the polymer reinforcement layer can be used as a tool to leverage presentation of the ECM molecules in ECM-based scaffolds. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 494-504, 2019.

Increased FDG-PET/CT pericardial uptake identifies acute pericarditis patients at high risk for relapse.

OBJECTIVES: We aimed to evaluate the prognostic value of FDG pericardial uptake using FDG-PET/CT in patients admitted for acute pericarditis with pericardial effusion. METHODS: In this monocentric retrospective cohort study, all patients admitted for idiopathic acute pericarditis with pericardial effusion from January 2009 to December 2016 who underwent a FDG-PET/CT at diagnosis were considered. Pericardial FDG uptake was measured by generating a volume of interest to calculate the maximal standardized uptake value. The primary outcome was the pericarditis relapse rate during follow-up. RESULTS: FDG-PET/CT was performed 23 [7-99] days after diagnosis in 39 patients (52 [18-83] years, 43.6% of women) admitted for acute pericarditis with pericardial effusion. During a median follow-up period of 7.6 [2.4-77.2] months, 7 (17.9%) patients suffered pericarditis relapse that occurred 3.8 [1.6-14.6] months after FDG-PET CT. In the multivariable analysis, pericardial FDG uptake at diagnosis (OR: 16.6; 95% confidence interval [CI]: 1.25 to 220.8; p = 0.033) was independently associated with pericarditis relapse. Eventually, patients with pericardial FDG uptake at diagnosis had a higher recurrence rate during follow up (p = 0.047). CONCLUSIONS: In acute pericarditis with pericardial effusion, increased FDG-PET/CT pericardial uptake is associated with a higher risk for relapse.

A Case of Cardiogenic Shock Secondary to Complement-Mediated Myopericarditis From Influenza B Infection.

Influenza B is a rare cause of myocarditis that is usually caused by histiocytic and mononuclear cellular infiltrates. We describe a 22-year-old female patient presenting with fulminant myopericarditis secondary to influenza B infection that deteriorated to cardiogenic shock. Endomyocardial biopsy results yielded myocardial necrosis through complement-mediated cellular injury without evidence of interstitial infiltrates. The rare cause of this patient's disease, along with the unique pathologic findings, are an important reminder of the diversity of potential findings in myocarditis.

Elevated Serum IgG4 Complicated by Pericardial Involvement with a Patchy (18)F-FDG Uptake in PET/CT: Atypical Presentation of IgG4-related Disease.

IgG4-related pericardial involvement has rarely been reported and its clinical features remain unknown. We herein report a case of a 50-year-old woman with pericarditis who presented with a fever, elevated C-reactive protein levels, elevated serum IgG4 concentrations, and thickened pericardium with a patchy (18)F-fluorodeoxyglucose (FDG) uptake. A biopsy specimen of (18)F-FDG accumulated in the mediastinal lymph nodes revealed an abundant infiltration of IgG4-bearing plasma cells without fibrosis. Moderate-dose glucocorticoids promptly resolved the physical, serological, and imaging abnormalities, thus indicating a relatively acute and reversible nature of IgG4-related pericardial involvement.

Acute pericarditis as the first manifestation of familial Mediterranean fever: a possible relationship with idiopathic recurrent pericarditis.

A 56-year-old man was admitted to our hospital due to periodic episodes of acute pericarditis. These episodes occurred monthly along with a high fever and elevation of the C-reactive protein (CRP) level. The patient became afebrile and his CRP level decreased following the administration of a non-steroidal anti-inflammatory drug. A mutation analysis revealed the heterozygote of the familial Mediterranean fever (FMF) gene (E84K, G304R). This finding confirmed our diagnosis, and we treated the patient with colchicine. He responded to treatment and has been visiting our hospital without disease recurrence. FMF should be included in the differential diagnosis of repeated episodes of pericarditis.

Spectrum of physiological and pathological cardiac and pericardial uptake of FDG in oncology PET-CT.

Cardiac uptake of 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) is frequently observed on FDG positron-emission tomography combined with computed tomography (PET-CT) performed for diagnosis, staging, and assessment of therapeutic response of lymphoma and solid cancers, despite careful patient preparation to limit myocardial glucose substrate utilisation. We illustrate the varied physiological patterns of cardiac FDG uptake, and show a spectrum of pathological conditions causing FDG uptake within myocardial and pericardial structures, due to clinically important benign and malignant diseases. Recognition and awareness of these various causes of FDG uptake in the heart, along with the appropriate use of correlative contrast-enhanced CT and magnetic resonance imaging (MRI) will facilitate correct interpretation.

Pericardial cytokines in neoplastic, autoreactive, and viral pericarditis.

Pericardial cytokine patterns in various diseases are not well established. We have analyzed pericardial proinflammatory (interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha) and immunoregulatory cytokines (transforming growth factor (TGF)-beta1 and interferon (IFN)-gamma) in patients with pericarditis, myocarditis, and ischemic heart disease. Pericardial fluid was obtained in 30 subsequent patients undergoing pericardiocentesis (Group 1: 60 % males, 52.4 ± 14.2 years) and in 21 patients during aortocoronary bypass surgery (Group 2: 42.9 % males, age 67.2 ± 7.4 years). After clinical, laboratory, echocardiography examination, fiberoptic pericardioscopy (Storz-AF1101Bl, Germany) and pericardial/epicardial biopsy Group 1 was subdivided to 40 % neoplastic, 36.6 % autoreactive, 10 % iatrogenic, and 13.3 % viral pericarditis. Samples were promptly aliquoted, frozen, and stored at -70 °C. The cytokines were estimated using quantikine enzyme amplified-sensitivity immuno-assays (R&D Systems, USA) and the results compared between neoplastic, viral, iatrogenic, and autoreactive pericarditis and surgical groups. IL-6 was significantly increased in PE versus serum in all forms of pericarditis (except in autoreactive) and increased in comparison with pericardial fluid of surgical patients. TNF-alpha was increased only in PE of patients with viral pericarditis in comparison with Group 2. TGF-beta1 was strikingly lower in the PE than in the serum of all pericarditis patients. However, TGF-beta1 levels in PE were significantly higher in Group 1 than in Group 2, except in viral pericarditis. IFN-gamma levels did not significantly differ between PE and serum or in comparison with Group 2. The cytokine pattern "high TNF-alpha/low TGF-beta1" was found in viral pericarditis and low IL-6 in autoreactive PE. Different etiologies of pericardial inflammation did not influence the IFN-gamma levels. IL-6 pericardial to serum ratio was significantly higher in autoreactive PE than in viral and neoplastic forms. However, TNF-alpha and IFN-gamma pericardial to serum ratios were significantly higher in viral than in autoreactive and neoplastic PE.

Massive pericardial effusion with cardiac tamponade secundary to cholesterol pericarditis.

The presence of cholesterol crystals in the pericardial fluid is a very rare finding of unknown pathogenesis with no more than 100 reported cases in literature. Patients with cholesterol pericarditis usually have large volume spills of slow development that are well tolerated, rarely causing cardiac tamponade or constrictive pericarditis. We report a case of cholesterol pericarditis with a severe pericardial effusion and cardiac tamponade in a patient with an uncertain diagnosis of tuberculosis.