Critical role for IL-6 in hypertrophy and fibrosis in chronic cardiac allograft rejection

Exercise training reduces cardiac fibrosis, promoting improvement in arrhythmias and cardiac dysfunction in an experimental model of chronic chagasic cardiomyopathy

Background

Chagas disease, caused by the parasite Trypanosoma cruzi, is associated with inflammation and fibrosis, which characterizes chronic Chagasic cardiomyopathy (CCC). CCC manifests as arrhythmias, hypertrophy or dilation of the left ventricle, and it may progress to heart failure. Therefore, interventions are needed to slow the progression of CCC. Aims: We investigated the effects of exercise training in an animal model of CCC.

Methods

C57BL/6 mice infected with Trypanosoma cruzi were submitted to a progressively treadmill exercise training protocol. The cardiac function was evaluated by echocardiogram and electrocardiogram. RT-qPCR and morphometric analyses were performed on samples of cardiac tissue to quantify inflammation and fibrosis.

Results

EKG analysis confirmed that all infected mice developed arrhythmias, with different degrees of severity. Exercise improved arrhythmias in 43.75% of chagasic trained mice, and the remaining mice did not show any alteration in EKG. The untrained chagasic group had no improvement in arrhythmias. The ventricular compliance in chagasic trained mice increased, as revealed by the reduction in isovolumetric relaxation time when compared to untrained mice. Exercise induced the reduction of gene expression of TGF-β, TNF-α, IL-1β, IL-6 and MMP-9 and reduced fibrosis in the heart tissue of chagasic mice.

Conclusion

Exercise reduced fibrosis in the heart and skeletal muscle, favoring the improvement of arrhythmias, and augment of cardiac complacency in mice with CCC, in addition to decreasing the expression of profibrotic and proinflammatory genes in the heart.

Identification of TIMP1-induced dysregulation of epithelial-mesenchymal transition as a key pathway in inflammatory bowel disease and small intestinal neuroendocrine tumors shared pathogenesis

Inflammatory Bowel Disease (IBD) is believed to be a risk factor for Small Intestinal Neuroendocrine Tumors (SI-NET) development; however, the molecular relationship between IBD and SI-NET has yet to be elucidated. In this study, we use a systems biology approach to uncover such relationships. We identified a more similar transcriptomic-wide expression pattern between Crohn's Disease (CD) and SI-NET whereas a higher proportion of overlapping dysregulated genes between Ulcerative Colitis (UC) and SI-NET. Enrichment analysis indicates that extracellular matrix remodeling, particularly in epithelial-mesenchymal transition and intestinal fibrosis mediated by TIMP1, is the most significantly dysregulated pathway among upregulated genes shared between both IBD subtypes and SI-NET. However, this remodeling occurs through distinct regulatory molecular mechanisms unique to each IBD subtype. Specifically, myofibroblast activation in CD and SI-NET is mediated through IL-6 and ciliary-dependent signaling pathways. Contrarily, in UC and SI-NET, this phenomenon is mainly regulated through immune cells like macrophages and the NCAM signaling pathway, a potential gut-brain axis in the context of these two diseases. In both IBD and SI-NET, intestinal fibrosis resulted in significant metabolic reprogramming of fatty acid and glucose to an inflammatory- and cancer-inducing state. This altered metabolic state, revealed through enrichment analysis of downregulated genes, showed dysfunctions in oxidative phosphorylation, gluconeogenesis, and glycogenesis, indicating a shift towards glycolysis. Also known as the Warburg effect, this glycolytic switch, in return, exacerbates fibrosis. Corresponding to enrichment analysis results, network construction and subsequent topological analysis pinpointed 7 protein complexes, 17 hub genes, 11 microRNA, and 1 transcription factor related to extracellular matrix accumulation and metabolic reprogramming that are candidate biomarkers in both IBD and SI-NET. Together, these biological pathways and candidate biomarkers may serve as potential therapeutic targets for these diseases.

Feasibility of Interleukin-6 Receptor Blockade in Cardiac Antibody-mediated Rejection

BACKGROUND

Antibody-mediated rejection (AMR) remains a significant cause of heart transplant mortality with few effective therapies.

METHODS

This study aimed to describe initial experience of using interleukin-6 receptor blockade with tocilizumab in the treatment of acute cardiac AMR at Barnes-Jewish Hospital/Washington University Transplant Center from July 2017 to May 2021 (n = 7). Clinical, echocardiographic, and serum alloantibody data were analyzed before and after treatment.

RESULTS

All participants demonstrated marked improvement in functional status. Echocardiographic data following 4-6 mo of tocilizumab revealed significant improvements in biventricular systolic function for all participants. Consistent reductions in donor-specific HLA or angiotensin type I receptor antibodies were not observed, suggesting that tocilizumab may act downstream of antibody production. No patient experienced drug-related complications that necessitated discontinuation of therapy.

CONCLUSIONS

These findings provide initial insights into the safety and efficacy of interleukin-6 receptor blockade in the treatment of cardiac AMR and support the design of larger prospective studies.

Molecular and Cellular Mechanisms of Action of Cannabidiol

Cannabidiol (CBD) is the primary non-psychoactive chemical from Cannabis Sativa, a plant used for centuries for both recreational and medicinal purposes. CBD lacks the psychotropic effects of Δ9-tetrahydrocannabinol (Δ9-THC) and has shown great therapeutic potential. CBD exerts a wide spectrum of effects at a molecular, cellular, and organ level, affecting inflammation, oxidative damage, cell survival, pain, vasodilation, and excitability, among others, modifying many physiological and pathophysiological processes. There is evidence that CBD may be effective in treating several human disorders, like anxiety, chronic pain, psychiatric pathologies, cardiovascular diseases, and even cancer. Multiple cellular and pre-clinical studies using animal models of disease and several human trials have shown that CBD has an overall safe profile. In this review article, we summarize the pharmacokinetics data, the putative mechanisms of action of CBD, and the physiological effects reported in pre-clinical studies to give a comprehensive list of the findings and major effects attributed to this compound.

Sudden cardiac death after heart transplantation: a population-based study

AIMS

The epidemiology of sudden cardiac death (SCD) after heart transplantation (HTx) remains imprecisely described. We aimed to assess the incidence and determinants of SCD in a large cohort of HTx recipients, compared with the general population.

METHODS AND RESULTS

Consecutive HTx recipients (n = 1246, 2 centres) transplanted between 2004 and 2016 were included. We prospectively assessed clinical, biological, pathologic, and functional parameters. SCD was centrally adjudicated. We compared the SCD incidence beyond the first year post-transplant in this cohort with that observed in the general population of the same geographic area (registry carried out by the same group of investigators; n = 19 706 SCD). We performed a competing risk multivariate Cox model to identify variables associated with SCD. The annual incidence of SCD was 12.5 per 1,000 person-years [95% confidence interval (CI), 9.7-15.9] in the HTx recipients cohort compared with 0.54 per 1,000 person-years (95% CI, 0.53-0.55) in the general population (P < 0.001). The risk of SCD was markedly elevated among the youngest HTx recipients with standardized mortality ratios for SCD up to 837 for recipients ≤30 years. Beyond the first year, SCD was the leading cause of death. Five variables were independently associated with SCD: older donor age (P = 0.003), younger recipient age (P = 0.001) and ethnicity (P = 0.034), pre-existing donor-specific antibodies (P = 0.009), and last left ventricular ejection fraction (P = 0.048).

CONCLUSION

HTx recipients, particularly the youngest, were at very high risk of SCD compared with the general population. The consideration of specific risk factors may help identify high-risk subgroups.

Targeting IL-6 to prevent cardiac allograft rejection

Outcomes following heart transplantation remain suboptimal with acute and chronic rejection being major contributors to poor long-term survival. IL-6 is increasingly recognized as a critical pro-inflammatory cytokine involved in allograft injury and has been shown to play a key role in regulating the inflammatory and alloimmune responses following heart transplantation. Therapies that inhibit IL-6 signaling have emerged as promising strategies to prevent allograft rejection. Here, we review experimental and pre-clinical evidence that supports the potential use of IL-6 signaling blockade to improve outcomes in heart transplant recipients.

Computational Analysis of Routine Biopsies Improves Diagnosis and Prediction of Cardiac Allograft Vasculopathy

Background: Cardiac allograft vasculopathy (CAV) is a leading cause of morbidity and mortality for heart transplant recipients. While clinical risk factors for CAV have been established, no personalized prognostic test exists to confidently identify patients at high vs. low risk of developing aggressive CAV. The aim of this investigation was to leverage computational methods for analyzing digital pathology images from routine endomyocardial biopsies (EMB) to develop a precision medicine tool for predicting CAV years before overt clinical presentation. Methods: Clinical data from 1-year post-transplant was collected on 302 transplant recipients from the University of Pennsylvania, including 53 'early CAV' patients and 249 'no-CAV' controls. This data was used to generate a 'clinical model' (ClinCAV-Pr) for predicting future CAV development. From this cohort, n=183 archived EMBs were collected for CD31 and modified trichrome staining and then digitally scanned. These included 1-year post-transplant EMBs from 50 'early CAV' patients and 82 no-CAV patients, as well as 51 EMBs from 'disease control' patients obtained at the time of definitive coronary angiography confirming CAV. Using biologically-inspired, hand-crafted features extracted from digitized EMBs, quantitative histologic models for differentiating no-CAV from disease controls (HistoCAV-Dx), and for predicting future CAV from 1-year post-transplant EMBs were developed (HistoCAV-Pr). The performance of histologic and clinical models for predicting future CAV (i.e. HistoCAV-Pr and ClinCAV-Pr, respectively) were compared in a held-out validation set, before being combined to assess the added predictive value of an integrated predictive model (iCAV-Pr). Results: ClinCAV-Pr achieved modest performance on the independent test set, with area under the receiver operating curve (AUROC) of 0.70. The HistoCAV-Dx model for diagnosing CAV achieved excellent discrimination, with an AUROC of 0.91, while HistoCAV-Pr model for predicting CAV achieved good performance with an AUROC of 0.80. The integrated iCAV-Pr model achieved excellent predictive performance, with an AUROC of 0.93 on the held-out test set. Conclusions: Prediction of future CAV development is greatly improved by incorporation of computationally extracted histologic features. These results suggest morphologic details contained within regularly obtained biopsy tissue have the potential to enhance precision and personalization of treatment plans for post-heart transplant patients.

Failure Analysis of TEVG’s II: Late Failure and Entering the Regeneration Pathway

Tissue-engineered vascular grafts (TEVGs) are a promising alternative to treat vascular disease under complex hemodynamic conditions. However, despite efforts from the tissue engineering and regenerative medicine fields, the interactions between the material and the biological and hemodynamic environment are still to be understood, and optimization of the rational design of vascular grafts is an open challenge. This is of special importance as TEVGs not only have to overcome the surgical requirements upon implantation, they also need to withhold the inflammatory response and sustain remodeling of the tissue. This work aims to analyze and evaluate the bio-molecular interactions and hemodynamic phenomena between blood components, cells and materials that have been reported to be related to the failure of the TEVGs during the regeneration process once the initial stages of preimplantation have been resolved, in order to tailor and refine the needed criteria for the optimal design of TEVGs.

The role of IL-6 in hyperlipidemia-induced accelerated rejection

Hyperlipidemia induces accelerated rejection of cardiac allografts and resistance to tolerance induction using costimulatory molecule blockade in mice due in part to anti-donor Th17 responses and reduced regulatory T cell function. Accelerated rejection in hyperlipidemic mice is also associated with increased serum levels of IL-6. Here, we examined the role of IL-6 in hyperlipidemia-induced accelerated rejection and resistance to tolerance. Genetic ablation of IL-6 prevented hyperlipidemia-induced accelerated cardiac allograft rejection. Using Th17-lineage fate tracking mice, we observed that IL-6 is required to promote the development of anti-donor Th17 lineage cells independently of antigen challenge. In contrast, the frequency of alloreactive T cells producing IL-2 or IFN-γ remained increased in hyperlipidemic IL-6-deficient mice. Ablation of IL-6 overcame hyperlipidemia-induced changes in Tregs, but was not sufficient to overcome resistance to costimulatory molecule blockade induced tolerance. We suggest that accelerated rejection in hyperlipidemic mice results from IL-6 driven anti-donor Th17 responses. While alterations in Tregs were overcome by ablation of IL-6, the reversal of hyperlipidemia-induced changes in Tregs was not sufficient to overcome increased Th1-type anti-donor T cell responses, suggesting that hyperlipidemia induced IL-6-independent effects on recipient immunity prevent tolerance induction.

Blockade of IL-6/IL-6R Signaling Attenuates Acute Antibody-Mediated Rejection in a Mouse Cardiac Transplantation Model

Acute antibody-mediated rejection (AAMR) is an important cause of cardiac allograft dysfunction, and more effective strategies need to be explored to improve allograft prognosis. Interleukin (IL)-6/IL-6R signaling plays a key role in the activation of immune cells including B cells, T cells and macrophages, which participate in the progression of AAMR. In this study, we investigated the effect of IL-6/IL-6R signaling blockade on the prevention of AAMR in a mouse model. We established a mouse model of AAMR for cardiac transplantation via presensitization of skin grafts and addition of cyclosporin A, and sequentially analyzed its features. Tocilizumab, anti-IL-6R antibody, and recipient IL-6 knockout were used to block IL-6/IL-6R signaling. We demonstrated that blockade of IL-6/IL-6R signaling significantly attenuated allograft injury and improved survival. Further mechanistic research revealed that signaling blockade decreased B cells in circulation, spleens, and allografts, thus inhibiting donor-specific antibody production and complement activation. Moreover, macrophage, T cell, and pro-inflammatory cytokine infiltration in allografts was also reduced. Collectively, we provided a highly practical mouse model of AAMR and demonstrated that blockade of IL-6/IL-6R signaling markedly alleviated AAMR, which is expected to provide a superior option for the treatment of AAMR in clinic.

IL-6 Directed Therapy in Transplantation

Purpose of Review

IL-6 is a pleiotropic, pro-inflammatory cytokine that plays an integral role in the development of acute and chronic rejection after solid organ transplantation. This article reviews the experimental evidence and current clinical application of IL-6/IL-6 receptor (IL-6R) signaling inhibition for the prevention and treatment of allograft injury.

Recent Findings

There exists a robust body of evidence linking IL-6 to allograft injury mediated by acute inflammation, adaptive cellular/humoral responses, innate immunity, and fibrosis. IL-6 promotes the acute phase reaction, induces B cell maturation/antibody formation, directs cytotoxic T-cell differentiation, and inhibits regulatory T-cell development. Importantly, blockade of the IL-6/IL-6R signaling pathway has been shown to mitigate its harmful effects in experimental studies, particularly in models of kidney and heart transplant rejection. Currently, available agents for IL-6 signaling inhibition include monoclonal antibodies against IL-6 or IL-6R and janus kinase inhibitors. Recent clinical trials have investigated the use of tocilizumab, an anti-IL-6R mAb, for desensitization and treatment of antibody-mediated rejection (AMR) in kidney transplant recipients, with promising initial results. Further studies are underway investigating the use of alternative agents including clazakizumab, an anti-IL-6 mAb, and application of IL-6 signaling blockade to clinical cardiac transplantation.

Summary

IL-6/IL-6R signaling inhibition provides a novel therapeutic option for the prevention and treatment of allograft injury. To date, evidence from clinical trials supports the use of IL-6 blockade for desensitization and treatment of AMR in kidney transplant recipients. Ongoing and future clinical trials will further elucidate the role of IL-6 signaling inhibition in other types of solid organ transplantation.

Post-intubation subglottic stenosis: aetiology at the cellular and molecular level

Subglottic stenosis (SGS) is a narrowing of the airway just below the vocal cords. This narrowing typically consists of fibrotic scar tissue, which may be due to a variety of diseases. This review focuses on post-intubation (PI) SGS. SGS can result in partial or complete narrowing of the airway. This narrowing is caused by fibrosis and can cause serious breathing difficulties. It can occur in both adults and children. The pathogenesis of post-intubation SGS is not well understood; however, it is considered to be the product of an abnormal healing process. This review discusses how intubation can change the local micro-environment, leading to dysregulated tissue repair. We discuss how mucosal inflammation, local hypoxia and biomechanical stress associated with intubation can promote excess tissue deposition that occurs during the pathological process of SGS.

COVID-19 may cause an increased incidence of subglottic stenosis (SGS). In this review, the cellular and molecular aetiology of post-intubation SGS is outlined and we discuss how better knowledge of the underlying biology can inform SGS management.https://bit.ly/2RSliRK

The regulatory effect of bromocriptine on cardiac hypertrophy by prolactin and D2 receptor modulation

BACKGROUND

Bromocriptine, a dopamine agonist, used for the treatment of hyperprolactinemia, type 2 diabetes, ovarian hyper-stimulation syndrome, has also effects on the cardiac remodeling process, but the mechanism of action is unknown. The aim of this work was to determinate the effect during hypertrophic process through molecular mechanisms that include prolactin receptor (Prlr) and receptor of dopamine 2 (D2 r) expression.

METHODS

We used a model of cardiac hypertrophy induced by an aortocaval fistula (ACF) surgery in rats. Protein concentrations of D2 r and Prlr were determined by western blotting. The treatment consisted in water (control), captopril (50 mg/kg/day), bromocriptine (3 mg/kg/day), and ACF group (n = 6 per group).

RESULTS

Our results showed that bromocriptine treatment decreases the hypertrophy index. Treatment with bromocriptine increases the protein expression of Prlr and D2 r in the cardiac tissue of rats with cardiac hypertrophy.

CONCLUSIONS

We concluded that bromocriptine has a protective effect on cardiac hypertrophy, and due to this effect, it may modulate the expression of Prlr and D2 r, which are involved in the development of cardiac hypertrophy.

Interleukin-6 promotes migration and extracellular matrix synthesis in retinal pigment epithelial cells

Proliferative vitreoretinopathy (PVR) is the most common cause of surgical failure in the rhegmatogenous retinal detachment (RD) treatment. Retinal pigment epithelial (RPE) cell proliferation, migration, and the synthesis of extracellular matrix (ECM) are intrinsic to the formation of a PVR membrane. High level of interleukin-6 (IL-6) has been found in the vitreous of PVR patients, while the role of IL-6 in RPE cells remaining further characterized. In the present study, we evaluated the potential regulatory effects of IL-6 on cell migration, ECM components, and transforming growth factor β2 (TGF-β2) expression in RPE cells. Furthermore, cell counting kit-8 (CCK‑8) assay was used to investigate cell proliferation activity. We found that IL-6 promoted fibronectin (Fn) and type I collagen (COL-1), TGF-β2 expression in RPE cells, also stimulate RPE cell migration effectively. Moreover, the induction of IL-6 activated the Janus kinase/signal transducers and activators of transcription (JAK/STAT3) and the nuclear factor kappa-B (NF-κB) signaling pathways significantly. Simultaneously, both JAK/STAT3 and NF-κB pathways inhibitors, WP1066 and BAY11-7082, alleviated IL-6-induced biological effects, respectively. However, it was noted that IL-6 had little effect on α-smooth muscle actin (α-SMA) expression. Collectively, our results reveal that IL-6 promotes RPE cell migration and ECM synthesis via activating JAK/STAT3 and NF-κB signaling pathways, which may play a crucial role in PVR formation.

CRLF1 Is a Key Regulator in the Ligamentum Flavum Hypertrophy

Hypertrophy of the ligamentum flavum (HLF) is one of the common causes of lumbar spinal stenosis (LSS). The key molecules and mechanisms responsible for HLF remain unclear. Here, we used an integrated transcriptome and proteomics analysis of human ligamentum flavum (LF), and subsequent immunohistochemistry and real-time PCR assays, to show upregulation of CRLF1 to be the dominant response to HLF. TGF-β1 significantly increased mRNA expression of CRLF1 through SMAD3 pathway. CRLF1 enhanced LF fibrosis via ERK signaling pathway at the post-transcriptional level and was required for the pro-fibrotic effect of TGF-β1. Knockdown of CRLF1 was shown here to reduce fibrosis caused by inflammatory cytokines and mechanical stress. Furthermore, we found that bipedal standing posture can cause HLF and upregulation of CRLF1 expression in mice LF. Overexpression of CRLF1 was indicated to cause HLF in vivo, whereas CRLF1 knockdown impeded the formation of HLF in bipedal standing mice. These results revealed a crucial role of CRLF1 in LF hypertrophy. We propose that inhibition of CRLF1 is a potential therapeutic strategy to treat HLF.

Role of Alarmins in the Pathogenesis of Systemic Sclerosis

Systemic sclerosis (SSc) is a rare chronic autoimmune disease associated with significant morbidity and mortality. Two main subsets of SSc are recognized: (i) diffuse cutaneous SSc with rapidly progressive fibrosis of the skin, lungs, and other internal organs; and (ii) limited cutaneous SSc, which is dominated by vascular manifestations, with skin and organ fibrosis generally limited and slowly progressing. In spite of intense investigation, both etiology and pathogenesis of SSc are still unknown. Genetic and environmental factors, as well as abnormalities of immune functions, are strongly suggested for etiology, while microvascular abnormalities, immune system activation, and oxidative stress are suggested for the pathogenesis. Recently, it has been found that a multitude of mediators and cytokines are implicated in the fibrotic processes observed in SSc. Among these, a central role could be exerted by “alarmins”, endogenous and constitutively expressed proteins/peptides that function as an intercellular signal defense. This review describes, in a detailed manner, the role of alarmins in the pathogenesis of scleroderma.

Circulating interleukins in relation to coronary artery disease, atrial fibrillation and ischemic stroke and its subtypes: A two-sample Mendelian randomization study

Whether thyroid dysfunction plays a causal role in the development of cancer remains inconclusive. We conducted a two-sample Mendelian randomization study to investigate the associations between genetic predisposition to thyroid dysfunction and 22 site-specific cancers. Single-nucleotide polymorphisms associated with four traits of thyroid function were selected from a genome-wide association meta-analysis with up to 72,167 European-descent individuals. Summary-level data for breast cancer and 21 other cancers were extracted from the Breast Cancer Association Consortium (122,977 breast cancer cases and 105,974 controls) and UK Biobank (367,643 individuals). For breast cancer, a meta-analysis was performed using data from both sources. Genetically predicted thyroid dysfunction was associated with breast cancer, with similar patterns of associations in the Breast Cancer Association Consortium and UK Biobank. The combined odds ratios of breast cancer were 0.94 (0.91–0.98; p = 0.007) per genetically predicted one standard deviation increase in TSH levels, 0.96 (0.91–1.00; p = 0.053) for genetic predisposition to hypothyroidism, 1.04 (1.01–1.07; p = 0.005) for genetic predisposition to hyperthyroidism and 1.07 (1.02–1.12; p = 0.003) per genetically predicted one standard deviation increase in free thyroxine levels. Genetically predicted TSH levels and hypothyroidism were inversely with thyroid cancer; the odds ratios were 0.47 (0.30-0.73; p = 0.001) and 0.70 (0.51-0.98; p = 0.038), respectively. Our study provides evidence of a causal association between thyroid dysfunction and breast cancer (mainly ER-positive tumors) risk. The role of TSH and hypothyroidism for thyroid cancer and the associations between thyroid dysfunction and other cancers need further exploration.

Nanodelivery of Mycophenolate Mofetil to the Organ Improves Transplant Vasculopathy

Inflammation occurring within the transplanted organ from the time of harvest is an important stimulus of early alloimmune reactivity and promotes chronic allograft rejection. Chronic immune-mediated injury remains the primary obstacle to the long-term success of organ transplantation. However, organ transplantation represents a rare clinical setting in which the organ is accessible ex vivo, providing an opportunity to use nanotechnology to deliver therapeutics directly to the graft. This approach facilitates the directed delivery of immunosuppressive agents (ISA) to target local pathogenic immune responses prior to the transplantation. Here, we have developed a system of direct delivery and sustained release of mycophenolate mofetil (MMF) to treat the donor organ prior to transplantation. Perfusion of a donor mouse heart with MMF-loaded PEG-PLGA nanoparticles (MMF-NPs) prior to transplantation abrogated cardiac transplant vasculopathy by suppressing intragraft pro-inflammatory cytokines and chemokines. Our findings demonstrate that ex vivo delivery of an ISA to donor organs using a nanocarrier can serve as a clinically feasible approach to reduce transplant immunity.

The role of interleukin-6 in intracellular signal transduction after chronic β-adrenergic stimulation in mouse myocardium

INTRODUCTION

Inflammatory mediators play an important role in development and progression of cardiovascular disease. Both adrenergic stimulation and high levels of interleukin-6 (IL-6) indicate an unfavorable outcome in patients with myocardial infarction or heart failure. Understanding the interaction between β-adrenergic stimulation and IL-6 in the myocardium may contribute to developing more effective treatments. The aim of this study was to verify the role of IL-6 in the effects of β-adrenergic stimulation in activating selected intracellular signaling pathways in mouse myocardium.

MATERIAL AND METHODS

Experiments were performed on 12-week-old male mice: 16 C57BL/6JIL6^{‑/‑TMKopf} (IL-6 KO) and 17 C57BL/6J (WT). Animals received intraperitoneal injections of isoproterenol (ISO, 50 mg/kg) or placebo (0.9% NaCl) once a day for 16 days. The phosphorylation of STAT3 (signal transducer and activator of transcription 3), ERK1/2 (extracellular-regulated kinases 1/2), Akt1/2/3, p-38, c-Raf and expression of SOCS3 (suppressor of cytokine signaling 3), PIAS1/3 (protein inhibitors of activated STAT) was assessed by western blotting in the myocardium 24 h after the last injection. Evaluation of gene expression downstream of these pathways was performed by real-time PCR.

RESULTS

Chronic ISO treatment leads to increased fibrosis of the myocardium in mice lacking IL-6, which is accompanied by increased activity of ERK1/2, p38 and reduced expression of SOCS3. Administration of ISO in IL-6 KO animals intensified gene expression of proteins activated by MAPK/ERK (myc; CEBPB; BMP4; Fasn; Tank), while it reduced expression of genes repressed by ERK 1/2 (Wisp1, Wnt1).

CONCLUSIONS

IL-6 plays an important role in regulating the activation of MAPK pathways in the mouse myocardium in response to chronic β-adrenergic stimulation.

The Roles of IL-1 Family Cytokines in the Pathogenesis of Systemic Sclerosis

The IL-1 family consists of 11 cytokines, 7 ligands with agonist activity (IL-1α, IL-1β, IL-18, IL-33, IL-36α, IL-36β, IL-36γ) and four members with antagonistic activities [IL-1 receptor antagonist (IL-1Ra), IL-36Ra, IL-37, IL-38]. Recent articles have described that most members of IL-1 family cytokines are involved in the process of innate and adaptive immunity as well as fibrosis in systemic sclerosis (SSc). IL-1 family gene polymorphisms, abnormal expression of IL-1 and its potential role in the fibrosis process have been explored in SSc. IL-33 and IL-18 have also been discussed in the recent years. IL-33 may contribute to the fibrosis of SSc, while IL-18 remains to be researched to confirm its role in fibrosis process. There is a lack of study on the pathophysiological roles of IL-36, IL-37, and IL-38 in SSc, which might provide us new study area. Here, we aim to give a brief overview of IL-1 family cytokines and discuss their pivotal roles in the pathogenesis of SSc.

HLA-DQ alloantibodies directly activate the endothelium and compromise differentiation of FoxP3high regulatory T lymphocytes

Development of donor-specific antibodies is associated with reduced allograft survival in renal transplantation. Recent clinical studies highlight the prevalence of human leukocyte antigen (HLA)-DQ antibodies amongst de novo donor-specific antibodies (DSAs), yet the specific contribution of these DSAs to rejection has not been examined. Antibody-mediated rejection primarily targets the microvasculature, so this study explored how patient HLA-DQ alloantibodies can modulate endothelial activation and so immunoregulation. HLA-DQ antibodies phosphorylated Akt and S6 kinase in microvascular endothelial cells. This activation prior to culture with alloreactive lymphocytes increased IL-6 and RANTES secretion. The antibody-mediated upregulation of IL-6 was indeed Akt-dependent. The binding of HLA-DQ antibodies to endothelial cells selectively reduced T cell alloproliferation and FoxP3^high Treg differentiation. In clinical studies, detection of HLA-DQ DSAs with other DSAs is associated with worse graft survival than either alone. Endothelial cells stimulated with HLA-DR and HLA-DQ antibodies showed a synergistic increase in pro-inflammatory cytokine secretion and a decrease in Treg expansion. HLA-DQ antibodies strongly promote pro-inflammatory responses in isolation and in combination with other HLA antibodies. Thus, our data give new insights into the pathogenicity of HLA-DQ DSAs.

Anti-IL-6 eluting immunomodulatory biomaterials prolong skin allograft survival

A primary goal in the management of burn wounds is early wound closure. The use of skin allografts represents a lifesaving strategy for severe burn patients, but their ultimate rejection limits their potential efficacy and utility. IL-6 is a major pleiotropic cytokine which critically links innate and adaptive immune responses. Here, we devised anti-IL-6 receptor eluting gelatin methacryloyl (GelMA) biomaterials (GelMA/anti-IL-6), which were implanted at the interface between the wound beds and skin allografts. Our visible light crosslinked GelMA/anti-IL-6 immunomodulatory biomaterial (IMB) demonstrated a stable kinetic release profile of anti-IL-6. In addition, the incorporation of anti-IL-6 within the GelMA hydrogel had no effect on the mechanical properties of the hydrogels. Using a highly stringent skin transplant model, the GelMA/anti-IL-6 IMB almost doubled the survival of skin allografts. The use of GelMA/anti-IL-6 IMB was far superior to systemic anti-IL-6 receptor treatment in prolonging skin allograft survival. As compared to the untreated control group, skin from the GelMA/anti-IL-6 IMB group contained significantly fewer alloreactive T cells and macrophages. Interestingly, the environmental milieu of the draining lymph nodes (DLNs) of the mice implanted with the GelMA/anti-IL-6 IMB was also considerably less pro-inflammatory. The percentage of CD4⁺ IFNγ⁺ cells was much lower in the DLNs of the GelMA/anti-IL-6 IMB group in comparison to the GelMA group. These data highlight the importance of localized immune delivery in prolonging skin allograft survival and its potential utility in treating patients with severe burns.

TGF-β1/p65/MAT2A pathway regulates liver fibrogenesis via intracellular SAM

BACKGROUND

Hepatic stellate cell (HSC) activation induced by transforming growth factor β1 (TGF-β1) plays a pivotal role in fibrogenesis, while the complex downstream mediators of TGF-β1 in such process are largely unknown.

METHODS

We performed pharmacoproteomic profiling of the mice liver tissues from control, carbon tetrachloride (CCl4)-induced fibrosis and NPLC0393 administrated groups. The target gene MAT2A was overexpressed or knocked down in vivo by tail vein injection of AAV vectors. We examined NF-κB transcriptional activity on MAT2A promoter via luciferase assay. Intracellular SAM contents were analyzed by LC-MS method.

FINDINGS

We found that methionine adenosyltransferase 2A (MAT2A) is significantly upregulated in the CCl4-induced fibrosis mice, and application of NPLC0393, a known small molecule inhibitor of TGF-β1 signaling pathway, inhibits the upregulation of MAT2A. Mechanistically, TGF-β1 induces phosphorylation of p65, i.e., activation of NF-κB, thereby promoting mRNA transcription and protein expression of MAT2A and reduces S-adenosylmethionine (SAM) concentration in HSCs. Consistently, in vivo and in vitro knockdown of MAT2A alleviates CCl4- and TGF-β1-induced HSC activation, whereas in vivo overexpression of MAT2A facilitates hepatic fibrosis and abolishes therapeutic effect of NPLC0393.

INTERPRETATION

This study identifies TGF-β1/p65/MAT2A pathway that is involved in the regulation of intracellular SAM concentration and liver fibrogenesis, suggesting that this pathway is a potential therapeutic target for hepatic fibrosis. FUND: This work was supported by National Natural Science Foundation of China (No. 81500469, 81573873, 81774196 and 31800693), Zhejiang Provincial Natural Science Foundation of China (No. Y15H030004), the National Key Research and Development Program from the Ministry of Science and Technology of China (No. 2017YFC1700200) and the Key Program of National Natural Science Foundation of China (No. 8153000502).

A Hand-Held Point-of-Care Biosensor Device for Detection of Multiple Cancer and Cardiac Disease Biomarkers Using Interdigitated Capacitive Arrays

This paper presents a hand-held point-of-care device that incorporates a lab-on-a-chip module with interdigitated capacitive biosensors for label-free detection of multiple cancer and cardiovascular disease biomarkers. The developed prototype is comprised of a cartridge incorporating capacitive biodetection sensors, a sensitive capacitive readout electronics enclosed in a hand-held unit, and data analysis software calculating the concentration of biomarkers using previously stored reference database. The capacitive biodetection sensors are made of interdigitated circular electrodes, which are preactivated with single (for detecting one biomarker) or multiple specific antibodies (for detecting multiple disease biomarkers). Detection principle of capacitive biosensor is based on measuring the level of capacitance change between interdigitated electrode pairs induced by the change in dielectric constant due to affinity-based electron exchange in between antibodies/antigens and electrodes. The more antibody-antigens binding occurs, the more capacitance change is measured due to the change in dielectric constant of the capacitance media. The device uses preactivated ready-to-use cartridges embedded with capacitive biosensors with shelf-life of three months under optimal conditions, and is capable of onsite diagnosis and can report the result in less than 30 min. The device is verified with real patient blood samples for six different disease biomarkers.

Cardiomyocytes and Macrophages Discourse on the Method to Govern Cardiac Repair

In response to pathophysiological stress, the cardiac tissue undergoes profound remodeling process that incorporates the elimination of dying resident cells, compensatory hypertrophy of functional cardiomyocytes, growth and remodeling of the vascular compartment and formation of a fibrotic scar. Accumulating evidences indicate that cardiac remodeling is, at least in part, controlled by a complex crosstalk between cardiomyocytes and macrophages. The strategic location of abundant macrophages to the proximity of cardiomyocytes suggest that they could regulate the fate of cardiomyocytes in the injured heart. As such, macrophages appear as critical support cells for cardiomyocytes and play central roles in cardiac hypertrophy, fibrosis and remodeling. Notably, the cardiac tissue expands heterogeneous population of cardiac macrophages through local proliferation of resident macrophage as well as recruitment and differentiation of blood-derived monocytes. It has also been suggested that cardiac-resident macrophages display distinct functional properties from that of monocyte-derived macrophages in cardiac tissue. Furthermore, macrophages are an overflowing source of biological entities with non-canonical roles on cardiac conduction or cardiomyocyte proliferation by regulating action potential diffusion or cardiac cell cycle reentry. Alternatively, stressed cardiomyocytes can trigger the release of a broad repertoire of instructive signals that can regulate macrophage number, skew their phenotype and therefore direct their beneficial or deleterious actions. In this review, we highlight recent discoveries describing how the intricate dialogue between cardiomyocytes and macrophages can shape the deleterious or healing signaling mechanisms in the injured cardiac tissue.

Donor biomarkers as predictors of organ use and recipient survival after neurologically deceased donor organ transplantation

PURPOSE

We sought to build prediction models for organ transplantation and recipient survival using both biomarkers and clinical information.

MATERIALS AND METHODS

We abstracted clinical variables from a previous randomized trial (n = 556) of donor management. In a subset of donors (n = 97), we measured two candidate biomarkers in plasma at enrollment and just prior to explantation.

RESULTS

Secretory leukocyte protease inhibitor (SLPI) was significant for predicting liver transplantation (C-statistic 0.65 (0.53, 0.78)). SLPI also significantly improved the predictive performance of a clinical model for liver transplantation (integrated discrimination improvement (IDI): 0.090 (0.009, 0.210)). For other organs, clinical variables alone had strong predictive ability (C-statistic >0.80). Recipient 3-years survival was 80.0% (71.9%, 87.0%). Donor IL-6 was significantly associated with recipient 3-years survival (adjusted Hazard Ratio (95%CI): 1.26(1.08, 1.48), P = .004). Neither clinical variables nor biomarkers showed strong predictive ability for 3-year recipient survival.

CONCLUSIONS

Plasma biomarkers in neurologically deceased donors were associated with organ use. SLPI enhanced prediction within a liver transplantation model, whereas IL-6 before transplantation was significantly associated with recipient 3-year survival. Clinicaltrials.gov: NCT00987714.

Cardiac Remodeling: Endothelial Cells Have More to Say Than Just NO

The heart is a highly structured organ consisting of different cell types, including myocytes, endothelial cells, fibroblasts, stem cells, and inflammatory cells. This pluricellularity provides the opportunity of intercellular communication within the organ, with subsequent optimization of its function. Intercellular cross-talk is indispensable during cardiac development, but also plays a substantial modulatory role in the normal and failing heart of adults. More specifically, factors secreted by cardiac microvascular endothelial cells modulate cardiac performance and either positively or negatively affect cardiac remodeling. The role of endothelium-derived small molecules and peptides—for instance NO or endothelin-1—has been extensively studied and is relatively well defined. However, endothelial cells also secrete numerous larger proteins. Information on the role of these proteins in the heart is scattered throughout the literature. In this review, we will link specific proteins that modulate cardiac contractility or cardiac remodeling to their expression by cardiac microvascular endothelial cells. The following proteins will be discussed: IL-6, periostin, tenascin-C, thrombospondin, follistatin-like 1, frizzled-related protein 3, IGF-1, CTGF, dickkopf-3, BMP-2 and−4, apelin, IL-1β, placental growth factor, LIF, WISP-1, midkine, and adrenomedullin. In the future, it is likely that some of these proteins can serve as markers of cardiac remodeling and that the concept of endothelial function and dysfunction might have to be redefined as we learn more about other factors secreted by ECs besides NO.

Ischemia augments alloimmune injury through IL-6-driven CD4+ alloreactivity

Ischemia reperfusion injuries (IRI) are unavoidable in solid organ transplantation. IRI augments alloimmunity but the mechanisms involved are poorly understood. Herein, we examined the effect of IRI on antigen specific alloimmunity. We demonstrate that ischemia promotes alloimmune activation, leading to more severe histological features of rejection, and increased CD4+ and CD8+ T cell graft infiltration, with a predominantly CD8+ IFNγ+ infiltrate. This process is dependent on the presence of alloreactive CD4+ T cells, where depletion prevented infiltration of ischemic grafts by CD8+ IFNγ+ T cells. IL-6 is a known driver of ischemia-induced rejection. Herein, depletion of donor antigen-presenting cells reduced ischemia-induced CD8+ IFNγ+ allograft infiltration, and improved allograft outcomes. Following prolonged ischemia, accelerated rejection was observed despite treatment with CTLA4Ig, indicating that T cell costimulatory blockade failed to overcome the immune activating effect of IRI. However, despite severe ischemic injury, treatment with anti-IL-6 and CTLA4Ig blocked IRI-induced alloimmune injury and markedly improved allograft survival. We describe a novel pathway where IRI activates innate immunity, leading to upregulation of antigen specific alloimmunity, resulting in chronic allograft injury. Based on these findings, we describe a clinically relevant treatment strategy to overcome the deleterious effect of IRI, and provide superior long-term allograft outcomes.

Cellular and Molecular Mediators of Intestinal Fibrosis

Intestinal fibrosis is a major complication of the inflammatory bowel diseases (IBD) and although inflammation is necessary for its development, it would appear that it plays a minor role in its progression as anti-inflammatory treatments in IBD do not prevent fibrosis once it has started. The processes that regulate fibrosis would thus appear to be distinct from those regulating inflammation and, therefore, a detailed understanding of these pathways is vital to the development of anti-fibrogenic strategies. There have been several recent reviews exploring what is known, and what remains unknown, about the development of intestinal fibrosis. This review is designed to add to this literature but with a focus on the cellular components that are involved in the development of fibrogenesis and the major molecular mediators that impact on these cells. The aim is to heighten the understanding of the factors involved in intestinal fibrogenesis so that detailed research can be encouraged in order to advance the processes that could lead to effective treatments.

Cellular and Molecular Mediators of Intestinal Fibrosis

Intestinal fibrosis is a major complication of the inflammatory bowel diseases (IBD) and although inflammation is necessary for its development, it would appear that it plays a minor role in its progression as anti-inflammatory treatments in IBD do not prevent fibrosis once it has started. The processes that regulate fibrosis would thus appear to be distinct from those regulating inflammation and, therefore, a detailed understanding of these pathways is vital to the development of anti-fibrogenic strategies. There have been several recent reviews exploring what is known, and what remains unknown, about the development of intestinal fibrosis. This review is designed to add to this literature but with a focus on the cellular components that are involved in the development of fibrogenesis and the major molecular mediators that impact on these cells. The aim is to heighten the understanding of the factors involved in intestinal fibrogenesis so that detailed research can be encouraged in order to advance the processes that could lead to effective treatments.

A New Concept of the Old Inhibitor NSC 74859 in Alleviating Cardiac Allograft Rejection and Extending Allograft Survival in Mice

Background

STAT1/4 has been suggested to be involved in cardiac allograft rejection. However, no direct evidence regarding STAT3 has been established in cardiac allograft rejection. Here, we hypothesized that inhibition of STAT3 attenuates cardiac allograft rejection.

Material/Methods

To test our hypothesis, homotopic mouse heart transplantation was carried out in syngeneic C57BL/6 to C57BL/6 strain mice with or without oral gavage with NSC 74859, an inhibitor of STAT3. The immune response was investigated using real-time PCR for CD4 and CD8 surface makers of T cells and CD14 of monocytes and cytokines, including IL-2, IL-15, and IL-6 of allografts at 3, 6, and 9 days after transplantation. Prognosis was also evaluated.

Results

We found that allografts with oral gavage of NSC 74859 whose CD4, CD8 T, and CD14 monocytes were significantly lower than that of allograft without oral gavage of NSC 74859, and the same was true for the expression of IL-2, IL-15, and IL-6. Immunohistochemical analysis of grafts showed reduced infiltration of monocytes/macrophages into the graft myocardium. Survival was also markedly extended in the NSC 74859 group.

Conclusions

Inhibition of IL-6/STAT3 using NSC 74859 was shown to remarkably alleviate cardiac allograft rejection in mice, indicating that the target against IL-6/STAT3 pathway might be clinically used as an alternative therapy for cardiac allograft rejection.

Novel Application of Localized Nanodelivery of Anti-Interleukin-6 Protects Organ Transplant From Ischemia-Reperfusion Injuries

Ischemia-reperfusion injury (IRI) evokes intragraft inflammatory responses, which markedly augment alloimmune responses against the graft. Understanding the mechanisms underlying these responses is fundamental to develop therapeutic regimens to prevent/ameliorate organ IRI. Here, we demonstrate that IRI results in a marked increase in mitochondrial damage and autophagy in dendritic cells (DCs). While autophagy is a survival mechanism for ischemic DCs, it also augments their production of interleukin (IL)-6. Allograft-derived dendritic cells (ADDCs) lacking autophagy-related gene 5 (Atg5) showed higher death rates posttransplantation. Transplanted ischemic hearts from CD11cCre/Atg5 conditional knockout mice showed marked reduction in intragraft expression of IL-6 compared with controls. To antagonize the effect of IL-6 locally in the heart, we synthesized novel anti-IL-6 nanoparticles with capacity for controlled release of anti-IL-6 over time. Compared with systemic delivery of anti-IL-6, localized delivery of anti-IL-6 significantly reduced chronic rejection with a markedly lower amount administered. Despite improved allograft histology, there were no changes to splenic T cell populations, illustrating the importance of local IL-6 in driving chronic rejection after IRI. These data carry potential clinical significance by identifying an innovative, targeted strategy to manipulate organs before transplantation to diminish inflammation, leading to improved long-term outcomes.

Signal Transducer and Activator of Transcription 3/MicroRNA-21 Feedback Loop Contributes to Atrial Fibrillation by Promoting Atrial Fibrosis in a Rat Sterile Pericarditis Model

Supplemental Digital Content is available in the text.

Background—

Postoperative atrial fibrillation is a frequent complication in cardiac surgery. The aberrant activation of signal transducer and activator of transcription 3 (STAT3) contributes to the pathogenesis of atrial fibrillation. MicroRNA-21 (miR-21) promotes atrial fibrosis. Recent studies support the existence of reciprocal regulation between STAT3 and miR-21. Here, we test the hypothesis that these 2 molecules might form a feedback loop that contributes to postoperative atrial fibrillation by promoting atrial fibrosis.

Methods and Results—

A sterile pericarditis model was created using atrial surfaces dusted with sterile talcum powder in rats. The inflammatory cytokines interleukin (IL)-1β, IL-6, transforming growth factor-β, and tumor necrosis factor-α, along with STAT3 and miR-21, were highly upregulated in sterile pericarditis rats. The inhibition of STAT3 by S3I-201 resulted in miR-21 downregulation, which ameliorated atrial fibrosis and decreased the expression of the fibrosis-related genes, α-smooth muscle actin, collagen-1, and collagen-3; reduced the inhomogeneity of atrial conduction; and attenuated atrial fibrillation vulnerability. Meanwhile, treatment with antagomir-21 decreased STAT3 phosphorylation, alleviated atrial remodeling, abrogated sterile pericarditis–induced inhomogeneous conduction, and prevented atrial fibrillation promotion. The culturing of cardiac fibroblasts with IL-6 resulted in progressively augmented STAT3 phosphorylation and miR-21 levels. S3I-201 blocked IL-6 induced the expression of miR-21 and fibrosis-related genes in addition to cardiac fibroblast proliferation. Transfected antagomir-21 decreased the IL-6–induced cardiac fibroblast activation and STAT3 phosphorylation. The overexpression of miR-21 in cardiac fibroblasts caused the upregulation of STAT3 phosphorylation, enhanced fibrosis-related genes, and increased cell numbers.

Conclusions—

Our results have uncovered a novel reciprocal loop between STAT3 and miR-21 that is activated after heart surgery and can contribute to atrial fibrillation.

A20 Haploinsufficiency Aggravates Transplant Arteriosclerosis in Mouse Vascular Allografts: Implications for Clinical Transplantation

BACKGROUND

Inflammation is central to the pathogenesis of transplant arteriosclerosis (TA). We questioned whether physiologic levels of anti-inflammatory A20 influence TA severity.

METHODS

We performed major histocompatibility complex mismatched aorta to carotid artery interposition grafts, using wild type (WT) or A20 heterozygote (HET) C57BL/6 (H-2) donors and BALB/c (H-2) recipients, and conversely BALB/c donors and WT/HET recipients. We analyzed aortic allografts by histology, immunohistochemistry, immunofluorescence, and gene profiling (quantitative real-time reverse-transcriptase polymerase chain reaction). We validated select in vivo A20 targets in human and mouse smooth muscle cell (SMC) cultures.

RESULTS

We noted significantly greater intimal hyperplasia in HET versus WT allografts, indicating aggravated TA. Inadequate upregulation of A20 in HET allografts after transplantation was associated with excessive NF-кB activation, gauged by higher levels of IkBα, p65, VCAM-1, ICAM-1, CXCL10, CCL2, TNF, and IL-6 (mostly localized to SMC). Correspondingly, cytokine-induced upregulation of TNF and IL-6 in human and mouse SMC cultures inversely correlated with A20 expression. Aggravated TA in HET versus WT allografts correlated with increased intimal SMC proliferation, and a higher number of infiltrating IFNγ and Granzyme B CD4 T cells and natural killer cells, and lower number of FoxP3 regulatory T cells. A20 haploinsufficiency in allograft recipients did not influence TA.

CONCLUSIONS

A20 haploinsufficiency in vascular allografts aggravates lesions of TA by exacerbating inflammation, SMC proliferation, and infiltration of pathogenic T cells. A20 single nucleotide polymorphisms associating with lower A20 expression or function in donors of vascularized allografts may inform risk and severity of TA, highlighting the clinical implications of our findings.

Cardioprotective Effect of Ulmus wallichiana Planchon in β-Adrenergic Agonist Induced Cardiac Hypertrophy

Ulmus wallichiana Planchon (Family: Ulmaceae), a traditional medicinal plant, was used in fracture healing in the folk tradition of Uttarakhand, Himalaya, India. The present study investigated the cardioprotective effect of ethanolic extract (EE) and butanolic fraction (BF) of U. wallichiana in isoprenaline (ISO) induced cardiac hypertrophy in Wistar rats. Cardiac hypertrophy was induced by ISO (5 mg/kg/day, subcutaneously) in rats. Treatment was performed by oral administration of EE and BF of U. wallichiana (500 and 50 mg/kg/day). The blood pressure (BP) and heart rate (HR) were measured by non-invasive blood pressure measurement technique. Plasma renin, Ang II, NO, and cGMP level were estimated using an ELISA kit. Angiotensin converting enzyme activity was estimated. BP and HR were significantly increased in ISO group (130.33 ± 1.67 mmHg vs. 111.78 ± 1.62 mmHg, p < 0.001 and 450.51 ± 4.90 beats/min vs. 347.82 ± 6.91 beats/min, respectively, p < 0.001). The BP and HR were significantly reduced (EE: 117.53 ± 2.27 mmHg vs. 130.33 ± 1.67 mmHg, p < 0.001, BF: 119.74 ± 3.32 mmHg vs. 130.33 ± 1.67 mmHg, p < 0.001); HR: (EE: 390.22 ± 8.24 beats/min vs. 450.51 ± 4.90 beats/min, p < 0.001, BF: 345.38 ± 6.79 beats/min vs. 450.51 ± 4.90 beats/min, p < 0.001) after the treatment of EE and BF of U. wallichiana, respectively. Plasma renin, Ang II, ACE activity was decreased and NO, cGMP level were increased. The EE and BF of U. wallichiana down regulated the expression of ANP, BNP, TNF-α, IL-6, MMP9, β1-AR, TGFβ1 and up regulated NOS3, ACE2 and Mas expression level, respectively. Thus, this study demonstrated that U. wallichiana has cardioprotective effect against ISO induced cardiac hypertrophy.

Basophils Trigger Fibroblast Activation in Cardiac Allograft Fibrosis Development

Fibrosis is a major component of chronic cardiac allograft rejection. Although several cell types are able to produce collagen, resident (donor-derived) fibroblasts are mainly responsible for excessive production of extracellular matrix proteins. It is currently unclear which cells regulate production of connective tissue elements in allograft fibrosis and how basophils, as potential producers of profibrotic cytokines, are involved this process. We studied this question in a fully MHC-mismatched model of heart transplantation with transient depletion of CD4(+) T cells to largely prevent acute rejection. The model is characterized by myocardial infiltration of leukocytes and development of interstitial fibrosis and allograft vasculopathy. Using depletion of basophils, IL-4-deficient recipients and IL-4 receptor-deficient grafts, we showed that basophils and IL-4 play crucial roles in activation of fibroblasts and development of fibrotic organ remodeling. In the absence of CD4(+) T cells, basophils are the predominant source of IL-4 in the graft and contribute to expansion of myofibroblasts, interstitial deposition of collagen and development of allograft vasculopathy. Our results indicated that basophils trigger the production of various connective tissue elements by myofibroblasts. Basophil-derived IL-4 may be an attractive target for treatment of chronic allograft rejection.

Cannabidiol Limits T Cell-Mediated Chronic Autoimmune Myocarditis: Implications to Autoimmune Disorders and Organ Transplantation

Myocarditis is a major cause of heart failure and sudden cardiac death in young adults and adolescents. Many cases of myocarditis are associated with autoimmune processes in which cardiac myosin is a major autoantigen. Conventional immunosuppressive therapies often provide unsatisfactory results and are associated with adverse toxicities during the treatment of autoimmune myocarditis. Cannabidiol (CBD) is a nonpsychoactive constituent of marijuana that exerts antiinflammatory effects independent of classical cannabinoid receptors. Recently, 80 clinical trials have investigated the effects of CBD in various diseases from inflammatory bowel disease to graft versus host disease. CBD-based formulations are used for the management of multiple sclerosis in numerous countries, and CBD also received U.S. Food and Drug Administration approval for the treatment of refractory childhood epilepsy and glioblastoma multiforme. Herein, using a well-established mouse model of experimental autoimmune myocarditis (EAM) induced by immunization with cardiac myosin emmulsified in adjuvant resulting in T cell-mediated inflammation, cardiomyocyte cell death, fibrosis and myocardial dysfunction, we studied the potential beneficial effects of CBD. EAM was characterized by marked myocardial T-cell infiltration, profound inflammatory response and fibrosis (measured by quantitative real-time polymerase chain reaction, histology and immunohistochemistry analyses) accompanied by marked attenuation of both systolic and diastolic cardiac functions measured with a pressure-volume conductance catheter technique. Chronic treatment with CBD largely attenuated the CD3+ and CD4+ T cell-mediated inflammatory response and injury, myocardial fibrosis and cardiac dysfunction in mice. In conclusion, CBD may represent a promising novel treatment for managing autoimmune myocarditis and possibly other autoimmune disorders and organ transplantation.

Metformin inhibits aldosterone-induced cardiac fibroblast activation, migration and proliferation in vitro, and reverses aldosterone+salt-induced cardiac fibrosis in vivo

The overall goals of this study were to investigate whether metformin exerts anti-fibrotic effects in aldosterone (Aldo)+salt-treated wild type mouse hearts, and determine the underlying molecular mechanisms in isolated adult cardiac fibroblasts (CF). In vitro, Aldo induced CF activation, migration, and proliferation, and these effects were inhibited by metformin. Further, Aldo induced PPM1A (Protein Phosphatase Magnesium Dependent 1A) activation and inhibited AMPK phosphorylation. At a pharmacologically relevant concentration, metformin restored AMPK activation, and inhibited Aldo-induced Nox4/H2O2-dependent TRAF3IP2 induction, pro-inflammatory cytokine expression, and CF migration and proliferation. Further, metformin potentiated the inhibitory effects of spironolactone, a mineralocorticoid receptor antagonist, on Aldo-induced collagen expression, and CF migration and proliferation. These results were recapitulated in vivo, where metformin reversed Aldo+salt-induced oxidative stress, suppression of AMPK activation, TRAF3IP2 induction, pro-inflammatory cytokine expression, and cardiac fibrosis, without significantly modulating systolic blood pressure. These in vitro and in vivo data indicate that metformin has the potential to reduce adverse cardiac remodeling in hypertensive heart disease.

Sustained PI3K Activation exacerbates BLM-induced Lung Fibrosis via activation of pro-inflammatory and pro-fibrotic pathways

Idiopathic pulmonary fibrosis (IPF) is a life-threatening disease with limited treatment options. Additionally, the lack of a complete understanding of underlying immunological mechanisms underscores the importance of discovering novel options for therapeutic intervention. Since the PI3K/PTEN pathway in myeloid cells influences their effector functions, we wanted to elucidate how sustained PI3K activity induced by cell-type specific genetic deficiency of its antagonist PTEN modulates IPF, in a murine model of bleomycin-induced pulmonary fibrosis (BIPF). We found that myeloid PTEN deficient mice (PTEN^MyKO), after induction of BIPF, exhibit increased TGF-β1 activation, mRNA expression of pro-collagens and lysyl oxidase as well as augmented collagen deposition compared to wild-type littermates, leading to enhanced morbidity and decreased survival. Analysis of alveolar lavage and lung cell composition revealed that PTEN^MyKO mice exhibit reduced numbers of macrophages and T-cells in response to bleomycin, indicating an impaired recruitment function. Interestingly, we found dysregulated macrophage polarization as well as elevated expression and release of the pro-fibrotic cytokines IL-6 and TNF-α in PTEN^MyKO mice during BIPF. This might point to an uncontrolled wound healing response in which the inflammatory as well as tissue repair mechanisms proceed in parallel, thereby preventing resolution and at the same time promoting extensive fibrosis.

miR-21 promotes fibrosis in an acute cardiac allograft transplantation model

AIMS

Cardiac transplantation is the only curative therapy for end-stage heart failure. Fibrosis is one of the major causes for impaired function of cardiac allografts. MicroRNAs, a class of small non-coding RNAs, play a critical role in the development of cardiovascular disease, but the role of microRNAs in cardiac allograft failure is not well understood.

METHODS AND RESULTS

To uncover a role of microRNAs during cardiac graft fibrosis, we generated global microRNA profiles in allogeneic (BALB/c in C57BL/6N) and isogeneic (C57BL/6N in C57BL/6N) murine hearts after transplantation. miR-21 together with cardiac fibrosis was increased in cardiac allografts compared with isografts. Likewise, patients with cardiac rejection after heart transplantation showed increased cardiac miR-21 levels. miR-21 was induced upon treatment with IL-6 in a monocyte cell line. Overexpression of miR-21 in this monocyte cell line activated a fibrotic gene programme and promoted monocyte-to-fibrocyte transition together with activation of chemokine (C-C) motif ligand 2 (monocyte chemoattractant protein 1) via the phosphatase and tensin homologue/activator protein 1 regulatory axis. In vivo, both genetic and pharmacological inhibition of miR-21 successfully reduced fibrosis and fibrocyte accumulation in cardiac allografts.

CONCLUSION

Thus, inhibition of miR-21 is a novel strategy to target fibrosis development in cardiac allografts.

Trypanosoma cruzi infection induces the expression of CD40 in murine cardiomyocytes favoring CD40 ligation-dependent production of cardiopathogenic IL-6

The inflammatory response in the myocardium is an important aspect of the pathogenesis of Chagas' heart disease raised by Trypanosoma cruzi. CD40, a transmembrane type I receptor belonging to the tumor necrosis factor receptor (TNFR) family, is expressed in a broad spectrum of cell types and is crucial in several inflammatory and autoimmune diseases. Activation of CD40 through ligation to CD40L (CD154) induces multiple effects, including the secretion of proinflammatory molecules. In the present study, we examined the ability of T. cruzi to trigger the expression of CD40 in cardiac myocytes in vitro and in a murine model of chagasic cardiomyopathy. Our results indicate, for the first time, that T. cruzi is able to induce the expression of CD40 in HL-1 murine cardiomyocytes. Moreover, ligation of CD40 receptor upregulated interleukin-6 (IL-6), associated with inflammation. Furthermore, the induction of this costimulatory molecule was demonstrated in vivo in myocardium of mice infected with T. cruzi. This suggests that CD40-bearing cardiac muscle cells could interact with CD40L-expressing lymphocytes infiltrating the heart, thus contributing to inflammatory injury in chagasic cardiomyopathy.

Role of interleukin-6 in regulation of immune responses to remodeling after myocardial infarction

Myocardial remodeling following myocardial infarction (MI) is emerging as key causes of chronic infarct mortality. Interleukin-6 is a classic pro-inflammatory cytokine needed to mount an effective immune response. It seems that interleukin-6 acts as an important role in the dynamic and superbly orchestrated process of innate immunity after MI. Interleukin-6 timely suppresses of innate immune signals to prevent the catastrophic consequences of uncontrolled inflammation on cardiac geometry and function, and thus tunes myocardial remodeling. A comprehensive understanding of biological processes of interleukin-6 in innate immunity leading to inflammatory response and disease-related ventricular remodeling is helpful to find the solution of chronic heart failure. To accomplish this, we reviewed the articles of interleukin-6 regard to inflammation, innate immunity, and cardiac remodeling. This review focuses on the role of interleukin-6 that dominates cell-mediated immunity, especially on neutrophils, monocytes, macrophages, and fibroblasts. In addition, we will also briefly discuss other inflammatory cytokines involved in this process within the paper.

SDF-1/CXCR4/CXCR7 is pivotal for vascular smooth muscle cell proliferation and chronic allograft vasculopathy

Chronic rejection remains a major obstacle in transplant medicine. Recent studies suggest a crucial role of the chemokine SDF-1 on neointima formation after injury. Here, we investigate the potential therapeutic effect of inhibiting the SDF-1/CXCR4/CXCR7 axis with an anti-SDF-1 Spiegelmer (NOX-A12) on the development of chronic allograft vasculopathy. Heterotopic heart transplants from H-2bm12 to B6 mice and aortic transplants from Balb/c to B6 were performed. Mice were treated with NOX-A12. Control animals received a nonfunctional Spiegelmer (revNOX-A12). Samples were retrieved at different time points and analysed by histology, RT-PCR and proliferation assay. Blockade of SDF-1 caused a significant decrease in neointima formation as measured by intima/media ratio (1.0 ± 0.1 vs. 1.8 ± 0.1, P < 0.001 AoTx; 0.35 ± 0.05 vs. 1.13 ± 0.27, P < 0.05 HTx). In vitro treatment of primary vascular smooth muscle cells with NOX-A12 showed a significant reduction in proliferation (0.42 ± 0.04 vs. 0.24 ± 0.03, P < 0.05). TGF-β, TNF-α and IL-6 levels were significantly reduced under SDF-1 inhibition (3.42 ± 0.37 vs. 1.67 ± 0.33, P < 0.05; 2.18 ± 0.37 vs. 1.0 ± 0.39, P < 0.05; 2.18 ± 0.26 vs. 1.6 ± 0.1, P < 0.05). SDF-1/CXCR4/CXCR7 plays a critical role in the development of chronic allograft vasculopathy (CAV). Therefore, pharmacological inhibition of SDF-1 with NOX-A12 may represent a therapeutic option to ameliorate chronic rejection changes.

Simultaneous deletion of Bax and Bak is required to prevent apoptosis and interstitial fibrosis in obstructive nephropathy

Proximal tubular injury and apoptosis are key mediators of the development of kidney fibrosis, a hallmark of chronic kidney disease. However, the molecular mechanism by which tubular apoptotic cell death leads to kidney fibrosis is poorly understood. In the present study, we tested the roles of Bcl-2-associated X (Bax) and Bcl-2 antagonist/killer (Bak), two crucial proteins involved in intrinsic apoptotic cell death, in the progression of kidney fibrosis. Mice with proximal tubule-specific Bax deletion, systemic deletion of Bak, and dual deletion of Bax and Bak were subjected to unilateral ureteral obstruction (UUO). Dual deficiency of Bax and Bak inhibited tubular apoptosis and atrophy. Consistent with decreased tubular injury, dual ablation of Bax and Bak suppressed UUO-induced inflammation and kidney fibrosis with decreased tubular cell cycle arrest, expression of fibrogenic and inflammatory cytokines, and oxidative stress in the kidney. Bax or Bak deficiency was insufficient to prevent apoptosis and all other aforementioned malevolent effects, suggesting compensatory mediation by each other in the respective signaling pathways. These data suggest that dual ablation of Bax and Bak in the kidney is required to prevent UUO-induced tubular apoptosis and the consequent kidney inflammation and fibrosis.

Kaempferol Promotes Transplant Tolerance by Sustaining CD4+FoxP3+ Regulatory T Cells in the Presence of Calcineurin Inhibitor

Calcineurin inhibitor cyclosporine is widely used as an immunosuppressant in clinic. However, mounting evidence has shown that cyclosporine hinders tolerance induction by dampening Tregs. Therefore, it is of paramount importance to overcome this pitfall. Kaempferol was reported to inhibit DC function. Here, we found that kaempferol delayed islet allograft rejection. Combination of kaempferol and low-dose, but not high-dose, of cyclosporine induced allograft tolerance in majority of recipient mice. Although kaempferol plus either dose of cyclosporine largely abrogated proliferation of graft-infiltrating T cells and their CTL activity, both proliferation and CTL activity in mice treated with kaempferol plus low-dose, but not high-dose, cyclosporine reemerged rapidly upon treatment withdrawal. Kaempferol increased CD4+FoxP3+ Tregs both in transplanted mice and in vitro, likely by suppressing DC maturation and their IL-6 expression. Reduction in Tregs by low dose of cyclosporine was reversed by kaempferol. Kaempferol-induced Tregs exhibited both allospecific and non-allospecific suppression. Administering IL-6 abrogated allograft tolerance induced by kaempferol and cyclosporine via diminishing CD4+FoxP3+ Tregs. Thus, for the first time, we demonstrated that kaempferol promotes transplant tolerance in the presence of low dose of cyclosporine, which allows for sufficient Treg generation while minimizing side effects, resulting in much-needed synergy between kaempferol and cyclosporine.