Protection against autoimmune myocarditis by gene transfer of interleukin-10 by electroporation

Modulation of TLR4/NFκB Pathways in Autoimmune Myocarditis

Myocarditis is an inflammatory and oxidative disorder characterized by immune cell recruitment in the damaged tissue and organ dysfunction. In this paper, we evaluated the molecular pathways involved in myocarditis using a natural compound, Coriolus versicolor, in an experimental model of autoimmune myocarditis (EAM). Animals were immunized with an emulsion of pig cardiac myosin and complete Freund's adjuvant supplemented with mycobacterium tuberculosis; thereafter, Coriolus versicolor (200 mg/Kg) was orally administered for 21 days. At the end of the experiment, blood pressure and heart rate measurements were recorded and the body and heart weights as well. From the molecular point of view, the Coriolus versicolor administration reduced the activation of the TLR4/NF-κB pathway and the levels of pro-inflammatory cytokines (INF-γ, TNF-α, IL-6, IL-17, and IL-2) and restored the levels of anti-inflammatory cytokines (IL-10). These anti-inflammatory effects were accompanied with a reduced lipid peroxidation and nitrite levels and restored the antioxidant enzyme activities (SOD and CAT) and GSH levels. Additionally, it reduced the histological injury and the immune cell recruitment (CD4+ and CD68+ cells). Moreover, we observed an antiapoptotic activity in both intrinsic (Fas/FasL/caspase-3) and extrinsic (Bax/Bcl-2) pathways. Overall, our data showed that Coriolus versicolor administration modulates the TLR4/NF-κB signaling in EAM.

Bioinspired macrophage-targeted anti-inflammatory nanomedicine: A therapeutic option for the treatment of myocarditis

Myocarditis is a disease characterized by inflammation of the heart muscle, which increases the risk of dilated cardiomyopathy and heart failure. Macrophage migration is a major histopathological hallmark of myocarditis, making macrophages a potential therapeutic target for the management of this disease. In the present study, we synthesized a bioinspired anti-inflammatory nanomedicine conjugated with protein G (PSL-G) that could target macrophages and induce macrophage polarization from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype. Notably, PSL-G exhibited a higher affinity for macrophages than non-macrophage cells. The addition of PSL-G decreased the levels of pro-inflammatory cytokines (e.g., IL-1α, IL-6, and TNF-α), but increased the level of the anti-inflammatory cytokine IL-10 in macrophages treated with lipopolysaccharide and/or interferon-γ. Furthermore, the lifetime of PSL-G in murine blood circulation was found to be significantly higher than that of PSL. Systemic injection of PSL-G into a mouse model of experimental autoimmune myocarditis remarkably reduced macrophage migration in the myocardium (16-fold compared with the positive control group) and myocardial fibrosis (8-fold). Based on these results and the fact that macrophages play a critical role in the pathogenesis of various diseases, we believe that bioinspired macrophage-targeted anti-inflammatory nanomedicines may be effective therapeutic options for the treatment of autoimmune and autoinflammatory diseases, especially myocarditis.

Cardiovascular Impairment in COVID-19: Learning From Current Options for Cardiovascular Anti-Inflammatory Therapy

In December 2019, Coronavirus Disease 2019 (COVID-19) caused by SARS-CoV-2, occurred in China and has currently led to a global pandemic. In addition to respiratory involvement, COVID-19 was also associated with significant multiple organ dysfunction syndrome (MODS). Cardiovascular impairment has been observed and is now drawing growing attention. Cardiovascular protective strategies are urgent and of great significance to the overall prognosis of COVID-19 patients. Direct viral infection, cytokine storm, and aggravation of existing cardiovascular diseases were recognized as possible mechanisms of cardiovascular impairment in COVID-19. Hyperactivated inflammation plays an important role in all three mechanisms and is considered to be fundamental in the development of cardiovascular impairment and MODS in COVID-19. Therefore, in addition to conventional cardiovascular treatment, anti-inflammatory therapy is a reasonable strategy for severe cases to further enhance cardiovascular protection and potentially mitigate MODS. We reviewed the inflammatory features and current promising treatments of COVID-19 as well as cardiovascular anti-inflammatory therapies that have been verified in previous clinical trials with positive outcomes. We believe that targeting the central pathway (IL-1β, TNF-α, IL-6), balancing the Th1 and Th2 response, and administering long-term anti-inflammatory therapy might be promising prospects to reduce cardiovascular impairment and even MODS during the acute and recovery phases of COVID-19. The cardiovascular anti-inflammatory therapies might be of great application value to the management of COVID-19 patients and we further propose an algorithm for the selection of anti-inflammatory therapy for COVID-19 patients with or at high risk of cardiovascular impairment. We recommend to take the experiences in cardiovascular anti-inflammatory therapy as references in the management of COVID-19 and conduct related clinical trials, while the clinical translation of novel treatments from preclinical studies or in vitro drug screening should proceed with caution due to unguaranteed efficacy and safety profiles.

A Critical Review of Electroporation as A Plasmid Delivery System in Mouse Skeletal Muscle

The gene delivery to skeletal muscles is a promising strategy for the treatment of both muscular disorders (by silencing or overexpression of specific gene) and systemic secretion of therapeutic proteins. The use of a physical method like electroporation with plate or needle electrodes facilitates long-lasting gene silencing in situ. It has been reported that electroporation enhances the expression of the naked DNA gene in the skeletal muscle up to 100 times and decreases the changeability of the intramuscular expression. Coelectransfer of reporter genes such as green fluorescent protein (GFP), luciferase or beta-galactosidase allows the observation of correctly performed silencing in the muscles. Appropriate selection of plasmid injection volume and concentration, as well as electrotransfer parameters, such as the voltage, the length and the number of electrical pulses do not cause long-term damage to myocytes. In this review, we summarized the electroporation methodology as well as the procedure of electrotransfer to the gastrocnemius, tibialis, soleus and foot muscles and compare their advantages and disadvantages.

Adiponectin deficiency has no effect in murine autoimmune myocarditis

BACKGROUND

Adiponectin is a hormone that together with its receptors modulates a number of metabolic processes including gluconeogenesis and lipid catabolism. It belongs to the C1QTNF (complement C1q tumor necrosis factor-related protein) family, which has a variety of members with high amino acid sequence homology and overlapping functions. Concentration of adiponectin in blood is inversely correlated with body fat percentage and cardiac risk factors like blood pressure and CRP (C-reactive protein) level. Studies have identified the existence of a cardiac adiponectin system. However, little is known about the role of this system in the pathogenesis of autoimmune myocarditis. Thus, we have studied the involvement of adiponectin in the development of this autoimmune disorder in a mouse model of experimental autoimmune myocarditis (EAM).

METHODS

Adiponectin knockout (ko) and wild type (wt) mice were immunized with cardiac troponin I (cTnI) to induce an EAM. To determine the severity of myocardial damage, inflammation and fibrosis were scored after HE and Afog staining and high sensitivity troponin T (hsTnT) level was measured. To detect if changes in specific inflammatory cell numbers could be observed between the genotypes, we performed immunohistochemical staining to detect T lymphocytes, B lymphocytes and macrophages. The level of the humoral immune response was determined through the measurement of cTnI-specific serum IgG autoantibodies. Relative mRNA expression of different cytokines, C1QTNF family members and adiponectin receptors in the heart tissue was analyzed with qPCR.

RESULTS

Animals immunized with cTnI developed autoimmune myocarditis with a significant deterioration of cardiac parameters compared to the corresponding control group. The adiponectin ko group immunized with cTnI showed a tendency towards increased inflammation, fibrosis, heart-to-body-weight ratio, infiltration pattern of T lymphocytes, B lymphocytes and macrophages, hsTnT concentration, humoral immune response and mRNA expression of interleukin 6 in the heart tissue and decreased weight gain compared to the wt group immunized with cTnI. However, the difference to the wt group treated with cTnI was not significant. The analysis of cardiac mRNA expression of adiponectin receptors and four C1QTNF family members, most suitable for fulfilling the functions of adiponectin in adiponectin ko mice, did not show any significant differences between adiponectin ko and wt group at all.

CONCLUSION

Our study reveals that the absence of adiponectin did not lead to a significantly increased impairment of cardiac function and was also unlikely to be compensated by its receptors or other C1QTNF family members in the murine model of EAM. Here, other synergistic or redundant effects might play a role and must be investigated in further studies to understand the role and function of adiponectin in autoimmune myocarditis.

[From a Ph.D. Thesis: Understanding the Past, Predicting the Future]

　Posey et al. have reported multiple molecular diagnoses in 4.5% of cases (101/2076) in which whole-exome sequencing was informative. Distinct disease phenotypes affect different organ systems, whereas overlapping disease phenotypes are more likely to be caused by two genes encoding proteins that interact within the same pathway. My research projects at the Niigata University of Pharmacy have investigated underlying mechanisms involved in human disease, including fatty acid metabolism, diabetic cardiomyopathy, atopic dermatitis, colitis, hepatitis, etc. Three students from abroad graduated this year from the Department of Clinical Pharmacology, Niigata University of Pharmacy and Applied Life Sciences. These students reported on treatments for heart disease, non-alcoholic steatohepatitis and atopic dermatitis, as well as the underlying mechanisms involved in each. The titles of these reports are "Study of the role of cardiac 14-3-3η protein in cardiac inflammation and adverse cardiac remodeling during heart failure in mice", "Non-alcoholic steatohepatitis: onset of mechanisms under diabetic background and treatment strategies" and "The role of HMGB1 and its cascade signaling pathway in atopic dermatitis". It can be concluded from these three theses that oxidative stress and inflammation are among the principal mechanisms underlying these diseases.

Targeted Therapy for Acute Autoimmune Myocarditis with Nano-Sized Liposomal FK506 in Rats

Immunosuppressive agents are used for the treatment of immune-mediated myocarditis; however, the need to develop a more effective therapeutic approach remains. Nano-sized liposomes may accumulate in and selectively deliver drugs to an inflammatory lesion with enhanced vascular permeability. The aims of this study were to investigate the distribution of liposomal FK506, an immunosuppressive drug encapsulated within liposomes, and the drug’s effects on cardiac function in a rat experimental autoimmune myocarditis (EAM) model. We prepared polyethylene glycol-modified liposomal FK506 (mean diameter: 109.5 ± 4.4 nm). We induced EAM by immunization with porcine myosin and assessed the tissue distribution of the nano-sized beads and liposomal FK506 in this model. After liposomal or free FK506 was administered on days 14 and 17 after immunization, the cytokine expression in the rat hearts along with the histological findings and hemodynamic parameters were determined on day 21. Ex vivo fluorescent imaging revealed that intravenously administered fluorescent-labeled nano-sized beads had accumulated in myocarditic but not normal hearts on day 14 after immunization and thereafter. Compared to the administration of free FK506, FK506 levels were increased in both the plasma and hearts of EAM rats when liposomal FK506 was administered. The administration of liposomal FK506 markedly suppressed the expression of cytokines, such as interferon-γ and tumor necrosis factor-α, and reduced inflammation and fibrosis in the myocardium on day 21 compared to free FK506. The administration of liposomal FK506 also markedly ameliorated cardiac dysfunction on day 21 compared to free FK506. Nano-sized liposomes may be a promising drug delivery system for targeting myocarditic hearts with cardioprotective agents.

Monocytic myeloid-derived suppressor cells from females, but not males, alleviate CVB3-induced myocarditis by increasing regulatory and CD4(+)IL-10(+) T cells

Coxsackievirus group B type 3 (CVB3) is a common etiologic agent of viral myocarditis and often causes sexually dimorphic myocarditis with increased incidence and mortality in male. So far, the underlying mechanism for the high male prevalence is not well elucidated. In this study, we deciphered the role of myeloid-derived suppressor cells (MDSCs) in the gender bias in murine CVB3-induced myocarditis by comparing their frequencies, subsets as well as immune suppressive functions. We found that much more myocardial MDSCs were enriched in infected females than males, with dramatically higher percentage ratio of CD11b⁺Ly6G-Ly6C^high monocytic subset (M-MDSCs) to CD11b⁺Ly6G⁺Ly6C^low granulocytic subset (G-MDSCs). Interestingly, more potent suppression on T cell proliferation was also evidenced in female-derived M-MDSCs. Consistently, adoptive transfer of female- but not male-derived M-MDSCs efficiently alleviated CVB3-induced myocarditis in male recipient mice, and this protection could be ascribed to the increased induction of regulatory and CD4⁺IL-10⁺ T cells. Our study suggested that myocardial MDSCs were distinctively induced not only in quantities but also in phenotypes and immune suppressive functions in CVB3-infected males and females; and female-derived more suppressive M-MDSCs contributed to their insensitivity to CVB3-induced myocarditis.

Diagnostic and prognostic biomarkers in acute myocarditis. Interleukin-10

Acute myocarditis is a major inflammatory heart disease with a variety of clinical courses from the acute to chronic phases represented by unexpected circulatory deterioration during hospitalization and progression to dilated cardiomyopathy. Predicting these disease courses is important for patient management. However, biomarkers have not been fully investigated. In addition, clinical profiles including symptoms, serological data, and electrocardiographic findings in acute myocarditis often mimic more common disorders such as coronary artery disease, which have reduced the diagnostic accuracy of acute myocarditis. These issues hamper the development of safer and earlier therapeutic interventions specific for acute myocarditis. Against this background, identifying simple prognostic and diagnostic biomarkers would contribute dramatically to the improvement in outcomes. Interleukin-10 may be a strong candidate for an excellent biomarker.

Beneficial effects of edaravone, a novel antioxidant, in rats with dilated cardiomyopathy

Edaravone, a novel antioxidant, acts by trapping hydroxyl radicals, quenching active oxygen and so on. Its cardioprotective activity against experimental autoimmune myocarditis (EAM) was reported. Nevertheless, it remains to be determined whether edaravone protects against cardiac remodelling in dilated cardiomyopathy (DCM). The present study was undertaken to assess whether edaravone attenuates myocardial fibrosis, and examine the effect of edaravone on cardiac function in rats with DCM after EAM. Rat model of EAM was prepared by injection with porcine cardiac myosin 28 days after immunization, we administered edaravone intraperitoneally at 3 and 10 mg/kg/day to rats for 28 days. The results were compared with vehicle-treated rats with DCM. Cardiac function, by haemodynamic and echocardiographic study and histopathology were performed. Left ventricular (LV) expression of NADPH oxidase subunits (p47^phox, p67^phox, gp91^phox and Nox4), fibrosis markers (TGF-β₁ and OPN), endoplasmic reticulum (ER) stress markers (GRP78 and GADD 153) and apoptosis markers (cytochrome C and caspase-3) were measured by Western blotting. Edaravone-treated DCM rats showed better cardiac function compared with those of the vehicle-treated rats. In addition, LV expressions of NADPH oxidase subunits levels were significantly down-regulated in edaravone-treated rats. Furthermore, the number of collagen-III positive cells in the myocardium of edaravone-treated rats was lower compared with those of the vehicle-treated rats. Our results suggest that edaravone ameliorated the progression of DCM by modulating oxidative and ER stress-mediated myocardial apoptosis and fibrosis.

Successful use of mRNA-nucleofection for overexpression of interleukin-10 in murine monocytes/macrophages for anti-inflammatory therapy in a murine model of autoimmune myocarditis

Background

Overexpression of interleukin-10 (IL-10) in murine CD11b⁺ monocytes/macrophages via GMP-adapted mRNA-nucleofection was expected to improve clinical outcome and reduce adverse side effects in autoimmune myocarditis. This study represents the proof of principle for a novel anti-inflammatory therapy using overexpression of IL-10 in murine monocytes/macrophages by mRNA-nucleofection for the treatment of autoimmune myocarditis.

Methods and Results

Autoimmune myocarditis was induced in A/J mice by subcutaneous immunization with troponin I. CD11b⁺ monocytes/macrophages were isolated from the peritoneum and IL-10 was overexpressed by mRNA-nucleofection. These cells were injected intravenously. Myocardial inflammation was assessed via histological and immunohistochemical examinations. Myocardial fibrosis was analyzed with Masson's trichrome staining. Antitroponin I antibodies were determined within the serum. Physical performance was evaluated using a running wheel and echocardiography. In vitro overexpression of IL-10 in CD11b⁺ monocytes/macrophages resulted in a 7-fold increased production of IL-10 (n=3). In vivo higher levels of IL-10 and less inflammation were detected within the myocardium of treated compared with control mice (n=4). IL-10–treated mice showed lower antitroponin I antibodies (n=10) and a better physical performance (n=10).

Conclusions

Application of IL-10–overexpressing CD11b⁺ monocytes/macrophages reduced inflammation and improved physical performance in a murine model of autoimmune myocarditis. Thus, the use of genetically modified monocytes/macrophages facilitated a targeted therapy of local inflammation and may reduce systemic side effects. Because the nucleofection technique is GMP adapted, an in vivo use in humans seems basically feasible and the transfer to other inflammatory diseases seems likely.

Quercetin offers cardioprotection against progression of experimental autoimmune myocarditis by suppression of oxidative and endoplasmic reticulum stress via endothelin-1/MAPK signalling

In order to test the hypothesis that treatment with quercetin at a dose of 10 mg/kg protects from the progression of experimental autoimmune myocarditis (EAM) to dilated cardiomyopathy (DCM), we have used the rat model of EAM induced by porcine cardiac myosin. Our results identified that the post-myocarditis rats suffered from elevated endoplasmic reticulum (ER) stress and adverse cardiac remodelling in the form of myocardial fibrosis, whereas the rats treated with quercetin have been protected from these changes as evidenced by the decreased myocardial levels of ER stress and fibrosis markers when compared with the vehicle-treated DCM rats. In addition, the myocardial dimensions and cardiac function were preserved significantly in the quercetin-treated rats in comparison with the DCM rats treated with vehicle alone. Interestingly, the rats treated with quercetin showed significant suppression of the myocardial endothelin-1 and also the mitogen activated protein kinases (MAPK) suggesting that the protection offered by quercetin treatment against progression of EAM involves the modulation of MAPK signalling cascade. Collectively, the present study provides data to support the role of quercetin in protecting the hearts of the rats with post myocarditis DCM.

Mucosal tolerance induction in autoimmune myocarditis and myocardial infarction

BACKGROUND

Antigen-specific therapy is a compelling approach for the treatment of autoimmune conditions. Primary goal is to induce the specific tolerization of self-reactive immune cells without altering host immunity against pathogens. We studied the effects of mucosal tolerance induction on cTnI-induced experimental autoimmune myocarditis (EAM) and post-infarct remodeling.

METHODS

Mucosal tolerance was induced by intranasal application of cTnI, alternatively anti-CD3 p.o. Protocols varied in frequency, dosage and time point of application before EAM. We then applied the most effective regimen to mice undergoing myocardial infarction in order to verify its effectiveness in post-infarct cardiac remodeling. The myocardium was evaluated on histological slides and for the cytokine secretion pattern, while echocardiography determined cardiac function.

RESULTS

A single dose of 100 μg of cTnI 7 days prior to myocarditis appeared to be most effective in suppressing inflammation and fibrosis (p = 0.03), while improving fractional shortening (p = 0.02). Treatment with intranasal cTnI upregulated IL-10 expression. On the other hand, frequent intranasal application of high doses of cTnI increased myocardial inflammation. Anti-CD3 p.o. showed the propensity to reduce myocardial inflammation and improve cardiac function. The single dose regimen of i.n. cTnI applied 7 days before a myocardial infarction reduced inflammation by trend (p=0.07) and improved heart function (p=0.002). Moreover, expression of matrix metalloproteinases 9 and 14 significantly decreased when treated with intranasal cTnI (p<0.01).

CONCLUSIONS

Depending on the optimal amount, the time period and the choice of antigen, effective mucosal tolerance can be achieved and represents an appealing therapeutic approach in the inflammatory process of cardiac remodeling.

Comparison of IL-10 and MCP-1-7ND gene transfer with AAV9 vectors for protection from murine autoimmune myocarditis

AIMS

Overexpression of therapeutic genes with potential disease-limiting effects, specifically at the site of inflammation, remains a major clinical challenge. In this study, we investigate the potential of adeno-associated virus (AAV)-9-mediated cardiac expression of the anti-inflammatory mediators interleukin (IL)-10 and a dominant-negative inhibitor of monocyte chemoattractant protein-1 (MCP1-7ND) on prevention of autoimmune myocarditis.

METHODS AND RESULTS

Autoimmune myocarditis was induced by immunizing A/J mice with subcutaneous injection of 120 µg cardiac troponin I (cTnI) on Days 0, 7, and 14. Two weeks prior to initial immunization, each mouse received a single systemic dose of 10(12) AAV9 vectors carrying the coding sequence of IL-10 or MCP1-7ND transcriptionally targeted to the heart. Mice were sacrificed 28 days after initial immunization for further analysis. Only expression of IL-10 resulted in a highly significant decrease in myocardial inflammation and fibrosis, as well as an increased ejection fraction compared with controls. Further analyses of cytokine profiles of cTnI-stimulated splenocytes from IL-10 and MCP1-7ND-treated mice revealed significant alterations compared with controls. In addition, transcript levels of chemokine receptor CCR4 and T-cell activation gene were significantly reduced in hearts of IL-10-treated mice as determined by quantitative real-time PCR.

CONCLUSION

Our study suggests that cardiac expression of IL-10 with AAV9 vectors is a promising therapeutic approach for autoimmune myocarditis.

Targeting the vicious inflammation-oxidative stress cycle for the management of heart failure

Oxidative stress and inflammation are each implicated independently in the development and progression of heart failure. Their interaction, however, is also evident throughout the process from initial injury to cardiac remodeling and failure. In the failing heart, the linkage between excessive reactive oxygen species (ROS) and the cytokine elaboration is manifested in shared elements and cross-promotion within downstream signaling pathways. In spite of this, the failure of anticytokine immunotherapy and antioxidant therapy, which had previously shown promise, suggests that a more complete perspective of ROS-cytokine interaction is required. The present review focuses on two of the major cytokines that are demonstrably connected to oxidative stress--the pro-inflammatory tumor necrosis factor-alpha (TNF-alpha) and the anti-inflammatory interleukin-10 (IL-10)--and their interactions in cardiac remodeling and failure. It is proposed that an optimal balance between TNF-alpha and IL-10 may be of crucial importance in mitigating both inflammation and oxidative stress processes leading to heart failure.

Lack of IL-6 during coxsackievirus infection heightens the early immune response resulting in increased severity of chronic autoimmune myocarditis

Background

Chronic myocarditis is often initiated by viral infection, the most common of which is coxsackievirus infection. The precise mechanism by which viral infection leads to chronic autoimmune pathology is poorly understood, however it is clear that the early immune response plays a critical role. Previous results have shown that the inflammatory cytokine interleukin (IL)-6 is integral to the development of experimental-induced autoimmune myocarditis. However, the function of IL-6 during viral-mediated autoimmunity has yet to be elucidated.

Methods and Results

To address the requirement of IL-6 during disease induction, IL-6 deficient mice were infected with coxsackievirus B3 (CB3). Following infection, mice lacking IL-6 developed increased chronic autoimmune disease pathology compared to wild type controls without a corresponding change in the level of viral replication in the heart. This increase in disease severity was accompanied by elevated levels of TNF-α, MCP-1, IL-10, activated T cells and cardiac infiltrating macrophage/monocytes. Injection of recombinant IL-6 early following infection in the IL-6 deficient mice was sufficient to lower the serum cytokines TNF-α and IL-10 as well as the serum chemokines MCP-1, MIP-1β, RANTES and MIG with a corresponding decrease in the chronic disease pathology strongly suggests an important regulatory role for IL-6 during the early response.

Conclusions

While IL-6 plays a pathogenic role in experimental-induced autoimmune disease, its function following viral-induced autoimmunity is not reprised. By regulating the early immune response and thereby controlling the severity of chronic disease, IL-6 directs the outcome of chronic autoimmune myocarditis.

Intrathecal transplantation of autologous macrophages genetically modified to secrete proenkephalin ameliorated hyperalgesia and allodynia following peripheral nerve injury in rats

To develop a novel genetic approach for the treatment of pain, we tested the transplantation of gene-transferred autologous macrophages by lumbar puncture. A rat neuropathic pain model was produced by chronic constriction of the sciatic nerve. Autologous macrophages were collected from the intraperitoneal space. Then human proenkephalin gene was transferred into the macrophages by electroporation. The gene-transferred macrophages were transplanted into the subarachnoid space by lumbar puncture. One week after transplantation, the heat hyperalgesia and allodynia induced by sciatic nerve constriction completely remitted. The analgesic action continued until at least 4 weeks after transplantation. The transplanted macrophages migrated into the spinal cord and expressed proenkephalin mRNA and Met-enkephalin protein. The method we tested in the present study may be a safe, simple and effective way to inhibit pain sensation after peripheral nerve injuries.

Involvement of Sema4A in the progression of experimental autoimmune myocarditis

Dilated cardiomyopathy often results from autoimmunity triggered by microbial infections during myocarditis. However, it remains unclear how immunological disorders are implicated in pathogenesis of autoimmune myocarditis. Here, we demonstrated that Sema4A, a class IV semaphorin, plays key roles in experimental autoimmune myocarditis (EAM). Dendritic cells pulsed with myosin heavy chain-alpha peptides induced severe myocarditis in wild-type mice, but not in Sema4A-deficient mice. In adoptive transfer experiments, CD4+ T-cells from wild-type mice induced severe myocarditis, while CD4+ T-cells from Sema4A-deficient mice exhibited considerably attenuated myocarditis. Our results indicated that Sema4A is critically involved in EAM by regulating differentiation of T-cells.

Alteration of IL-17 related protein expressions in experimental autoimmune myocarditis and inhibition of IL-17 by IL-10-Ig fusion gene transfer

BACKGROUND

T-helper (Th)1/Th2 cytokine balance plays an important role in the pathogenesis of myocarditis. Recently, some studies indicate that interleukin (IL)-17, known as a T cell (Th17)-derived proinflammatory cytokine, is the major mediator of tissue inflammation in inflammatory and autoimmune diseases. Experimental autoimmune myocarditis (EAM) is a T cell-mediated autoimmune disease; however, the pathogenic role of IL-17 in the development of rat EAM remains largely unknown.

METHODS AND RESULTS

In the present study, alterations of IL-17-related protein expressions were investigated and then the effect of hydrodynamic-based delivery of plasmid DNA encoding the IL-10-Ig gene on rat EAM and the effect of IL-10-Ig on IL-17 was evaluated. The results showed that IL-17 was expressed more highly than IFN-gamma expressed by Th1 cells in alphabetaT cells and the peaks of IL-17 related protein expression in the heart were the early phase of EAM. Moreover, we observed that IL-10-Ig gene therapy was effective in controlling EAM and that IL-10-Ig significantly suppressed the expression of IL-17 as well as other proinflammatory cytokines, IL-1beta and TNF-alpha, in IL-1-stimulated splenocytes cultured from EAM rats.

CONCLUSIONS

IL-17 is highly produced by alphabetaT cells in the early phase of EAM hearts and IL-17 inhibition might be a possible mechanism of the amelioration of EAM by IL-10-Ig treatment. These data suggest that IL-17 produced by Th17 plays an important role in the pathogenesis of rat EAM.

Delivery of DNA into muscle for treating systemic diseases: advantages and challenges

An efficient and safe method to deliver DNA in vivo is a requirement for several purposes, such as the study of gene function and gene therapy applications. Among the different nonviral delivery methods currently under investigation, in vivo DNA electrotransfer has proven to be one of the most efficient and simple methods. This technique is a physical method of gene delivery consisting of a local application of electric pulses after injection of DNA. This technique can be applied to almost any tissue of a living animal, including tumors, skin, liver, kidney, artery, retina, cornea, or even brain, but the focus of this review will be on electrotransfer of plasmid DNA into skeletal muscle and its possible therapeutic uses for systemic diseases. Skeletal muscle is a good target for electrotransfer of DNA because of the following features: a large volume of easily accessible tissue, an endocrine organ capable of expressing several local and systemic factors, and muscle fibers as postmitotic cells have a long lifespan, which allows long-term gene expression. In this review, we will describe the main characteristics of DNA electrotransfer, including toxicity and safety issues related to this technique. We will focus on the important possible therapeutic applications of electrotransfer for systemic diseases demonstrated in animal models in the recent years, in the fields of monogenic diseases, tissue-specific diseases, metabolic disorders, immune-system-related diseases, and cancer. Finally, we will discuss the advantages and challenges of this technique.

Enhancement of antibody and cellular immune responses to malaria DNA vaccines by in vivo electroporation

We evaluated the effectiveness of in vivo electroporation (EP) for the enhancement of immune responses induced by DNA plasmids encoding the pre-erythrocytic Plasmodium yoelii antigens PyCSP and PyHEP17 administered intramuscularly and intradermally to mice. EP resulted in a 16- and 2-fold enhancement of antibody responses to PyCSP and PyHEP17, respectively. Immunization with 5 microg of DNA via EP was equivalent to 50 microg of DNA via conventional needle, thus reducing by 10-fold the required dose to produce a given effect. Moreover, IFN-gamma responses were increased by approximately 2-fold. Data demonstrate the potential of EP to enhance immune responses to DNA vaccines against infectious agents.

Autoimmunological features in inflammatory cardiomyopathy

During recent years, increasing evidence has been obtained that cellular as well as humoral autoimmunity is involved in the pathogenesis of dilated cardiomyopathy (DCM). The immune system is generally activated by viral infections with the objective of virus elimination from the myocardium. However, a relevant number of patients demonstrate viral persistence and/or chronic inflammation in the myocardium. This chronic myocardial inflammation, defined by chronic inflammation, is termed "inflammatory cardiomyopathy" according to the WHO classification of cardiomyopathies. Chronic inflammation is frequently followed by the development of autoimmunity. A breakdown in the control mechanisms protecting against autoimmune reactions by both presentation of normally not accessible self-antigens and bystander- activation, induced by the pathogen, leads to the formation of autoreactive antibodies and T cells. The auto-reactive antibodies interact directly with heart tissue resulting in altered signal transduction or complement activation, whereas the T cell-mediated mechanisms include direct attack by cytotoxic T cells or indirect effects of cytotoxic cytokines released by stimulated T cells or macrophages.

Sustained nitric oxide synthesis contributes to immunopathology in ongoing myocarditis attributable to interleukin-10 disorders

Ongoing coxsackievirus B3 (CVB3) myocarditis is characterized by persistence of viral RNA and chronic inflammation primarily mediated by macrophages and T cells. Activated macrophages produce anti-viral effector molecules comprising reactive nitrogen intermediates; however, reactive nitrogen intermediates also contribute to host tissue damage. Controlled activation of macrophages depends on interferon (IFN)-gamma and interleukin (IL)-10. To evaluate mechanisms involved in CVB3-induced pathogenesis of myocarditis, we determined the relationship of inducible nitric-oxide synthase (iNOS) mRNA expression with IFN-gamma and IL-10 secretion during CVB3 infection in different mouse strains. We found in susceptible A.BY/SnJ mice that develop ongoing myocarditis, a low and delayed IFN-gamma secretion and highly diminished IL-10 production compared with resistant C57BL/6 mice. Consequently, iNOS mRNA synthesis was delayed but clearly prolonged in susceptible mice. IL-10 gene-deficient mice confirmed the regulatory role of IL-10 in the outcome of CVB3 myocarditis. These mice did not establish a persistent cardiac infection and revealed IFN-gamma secretion kinetics similar to resistant mice but showed a slightly elongated cardiac iNOS mRNA expression resulting in extended myocarditis. We conclude that coordinated secretion of IFN-gamma and IL-10 is crucial for the effective resolution of CVB3 myocarditis. Moreover, lack of regulatory IL-10 leads to uncontrolled iNOS mRNA production, thus contributing to ongoing myocardial injury.

Hydrodynamic-based delivery of an interleukin-22-Ig fusion gene ameliorates experimental autoimmune myocarditis in rats

IL-22 is one of several cytokines with limited homology to IL-10. However, the biological activities of IL-22 are mostly unknown. The purpose of this study was to evaluate the effect of IL-22 on rat experimental autoimmune myocarditis (EAM) and elucidate an aspect of the biological activities of IL-22. Rats were immunized on day 0; IL-22-Ig-treated rats were injected with pCAGGS-IL-22-Ig and control rats with pCAGGS-Ig using hydrodynamics-based gene delivery on day 1 or day 6. IL-22-Ig gene therapy administered on day 1 or day 6 after immunization was effective in controlling EAM as monitored by the heart weight to body weight ratio, and the myocarditis area in rats was sacrificed on day 17. Examination of the expression of IL-22-related genes in purified cells from EAM hearts suggested that IL-22-Ig acting target cells were noncardiomyocytic (NC) noninflammatory cells such as fibroblasts, smooth muscle cells, and endothelial cells. Therefore, we examined the effect of rIL-22 or serum containing IL-22-Ig on the expression of immune-relevant genes in IL-1-stimulated NC cells cultured from EAM hearts. Results showed that the expression of immunologic molecules (PGE synthase, cyclooxygenase-2, MIP-2, MCP-1, IL-6, and cytokine-induced neutrophil chemoattractant-2) in IL-1-stimulated NC cells was significantly decreased by rIL-22 or serum containing IL-22-Ig. EAM was suppressed by hydrodynamics-based delivery of plasmid DNA encoding IL-22-Ig, and the reason for this effectiveness may be that IL-22 suppressed gene expression of PG synthases, IL-6, and chemokines in activated NC noninflammatory cells.

Prevention of experimental autoimmune myocarditis by hydrodynamics-based naked plasmid DNA encoding CTLA4-Ig gene delivery

BACKGROUND

Rat experimental autoimmune myocarditis (EAM) is a T cell-mediated disease that resembled the giant cell myocarditis seen in humans. Soluble CTLA4 improves some autoimmune diseases by blocking costimulatory signals on T cell. We investigated the effect of hydrodynamics-based naked plasmid DNA encoding CTLA4-immunoglobulin (Ig) gene delivery.

METHODS AND RESULTS

Lewis rats were immunized with cardiac myosin and treated with hydrodynamic-based transfection, namely a rapid tail vein injection of a large volume of pCAGGS encoding CTLA4-Ig chimera solution on Day 0. The vector-derived CTLA4-Ig mRNA expressions were mainly detected in the liver and plasma CTLA4-Ig protein levels were maintained at about 2 mug/mL during the experiment period. On Day 17, the ratio of heart to body weight, the amount of mRNA of atrial natriuretic peptide, and the inflammatory areas in CTLA4 group were significantly lower than in the control group treated with empty plasmid. Maximum rate of intraventricular pressure rise and decline (dP/dT), minimum dP/dT, left ventricular end-diastolic pressure, and central venous pressure improved significantly after treatment with CTLA4-Ig. On Day 14, expressions of IL-2 in popliteal lymph nodes in the CTLA4-Ig group were significantly lower than in the control group.

CONCLUSION

Hydrodynamics-based transfection of plasmid encoding CTLA4-Ig chimera dramatically prevented EAM.

In vivo NMR imaging evaluation of efficiency and toxicity of gene electrotransfer in rat muscle

In vivo gene electrotransfer (ET) is a simple method of gene delivery in various tissues relying on the injection of plasmid DNA followed by application of electric pulses. Noninvasive tools are needed to evaluate the ET efficiency and the resulting tissue damages. In this study, we performed ET of rat tibialis muscle after injection of either a plasmid coding for luciferase or a contrast agent (CA) detected by using magnetic resonance imaging (MRI). Plasmid expression and CA intracellular trapped quantity were compared throughout the electric field intensity range 0-300 V/cm. Although the CA trapped quantity reflects only the electropermeabilization step, both measurements were correlated. MRI measurements gave easy access to tridimensional visualization of the labelled zones where the CA has been injected and the applied electric field had a value allowing permeabilization. We also performed MRI measurements of the water transverse relaxation time T2 as an indicator of tissue modification, and tested whether another CA specific for necrosis could be used to detect muscle necrosis at high electric field intensity. In conclusion, MRI measurements may bring multiparametric information upon the efficiency and tissue toxicity of an ET protocol by using a simple and safe CA.

Central neurotranspeptide, alpha-melanocyte-stimulating hormone (alpha-MSH) is upregulated in patients with congestive heart failure

BACKGROUND

Alpha-melanocyte-stimulating hormone (alpha-MSH), a pro-opiomelanocortin (POMC) derivative, is a neuropeptide with potent anti-inflammatory properties that inhibits tissue injury in a wide array of inflammation models.

OBJECTIVE

To determine if alpha-MSH is involved in the development of congestive heart failure (CHF) with the specific aim of examining its peripheral source and one of the mechanisms.

METHODS

The circulating levels of alpha-MSH were measured in 115 patients with CHF using a double-antibody radioimmunoassay. To determine one of the sources of circulating alpha-MSH, human peripheral blood mononuclear cells (PBMC) were stimulated with lipopolysaccharide (LPS) or tumor necrosis factor (TNF)-alpha. Furthermore, to clarify one of the functions of alpha-MSH, PBMC were cultured in the presence or absence of alpha-MSH.

RESULTS

Plasma levels of alpha-MSH were significantly higher in NYHA class II patients with CHF than in control subjects (p<0.0001). A significant correlation was found between the levels of alpha-MSH and high-sensitive testing for C-reactive protein in patients with CHF (r=0.41, p<0.0005). PBMC stimulated with LPS or TNF-alpha released alpha-MSH in a concentration-dependent manner. alpha-MSH inhibited LPS-induced TNF-alpha production, and alpha-MSH simultaneously augmented production of interleukin (IL)-10 by PBMC.

CONCLUSIONS

Circulating alpha-MSH was increased in patients with CHF. Inflammatory response induced alpha-MSH production in cultured human PBMC. Treatment of alpha-MSH could modify the immunobalance between inflammatory and anti-inflammatory responses in cultured PBMC. These findings suggest that alpha-MSH may play an important role in the pathophysiology of CHF.

The effect of hydrodynamics-based delivery of an IL-13-Ig fusion gene for experimental autoimmune myocarditis in rats and its possible mechanism

Interleukin (IL)-13 is a pleiotropic cytokine secreted by activated Th2 T lymphocytes. Th1 cytokines are assumed to exacerbate and Th2 cytokines to ameliorate rat experimental autoimmune myocarditis (EAM). Here, we examined the effect of IL-13 on EAM, using a hydrodynamics-based delivery of an IL-13-Ig fusion gene, as well as the possible mechanism of its effect. Rats were immunized on day 0, and IL-13-Ig-treated rats were injected with pCAGGS-IL-13-Ig, and control rats with pCAGGS-Ig, on day 1 or 7. On day 17, the IL-13-Ig gene therapy was effective in controlling EAM as monitored by a decreased heart weight/body weight ratio, by reduced myocarditis and by reduced atrial natriuretic peptide mRNA in the heart, as a heart failure marker. On the basis of IL-13 receptor mRNA expression in separated cells from EAM hearts, we proposed that IL-13-Ig target cells were CD11b(+) cells and non-cardiomyocytic noninflammatory (NCNI) cells, such as fibroblasts, smooth muscle or endothelial cells. IL-13-Ig inhibited expression of the genes for prostaglandin E synthase, cyclooxygenase-2, inducible nitric oxide synthase, IL-1beta and TNF-alpha in cultivated cells from EAM hearts, while it enhanced expression of the IL-1 receptor antagonist gene. We conclude that IL-13-Ig ameliorates EAM and suppose that its effectiveness may be due to the influence on these immunologic molecules in CD11b(+) and NCNI cells.

Short-term prognostic value of initial serum levels of interleukin-10 in patients with acute myocarditis

The disease course of acute myocarditis has a wide spectrum and the predictors of the prognosis in patients with acute myocarditis have not yet been established. In the pathogenesis of myocarditis, the cytokine environment is important. In this study, we examined the predictive values of serum levels of interleukin-10 (IL-10) and IL-12 in the short-term prognosis of patients with acute myocarditis. Twenty-four consecutive patients who had been diagnosed as having acute active myocarditis were analyzed and monitored for 2 months. The patients with myocarditis were divided into the survival group (n=16) and the non-survival group (n=8). Initial serum levels of IL-10 (P=0.0015) and IL-12 (P=0.012) in the non-survival group were significantly higher than those of the survival group, and there was a significant correlation between IL-10 and IL-12 levels (P<0.0001). The univariate analyses showed that increased serum levels of IL-10 (hazard ratio 1.041, P=0.0004) and IL-12 (hazard ratio 1.128, P=0.0346) were significant predictors of mortality. In the Kaplan-Meier analysis, high levels of IL-10 (>or=7.0 pg/ml) (P=0.0239) strongly predicted high mortality. In conclusion, the elevation in serum IL-10 levels at the initial phase appeared to predict poor short-term prognosis in patients with acute myocarditis.

Inhibition of mast cells by interleukin-10 gene transfer contributes to protection against acute myocarditis in rats

Progression of acute myocarditis involves a variety of inflammatory events. Mast cells have been implicated as the source of various cytokines, chemokines and histamine in acute inflammation and fibrosis. Interleukin (IL)-10 has well-known immunomodulatory actions that are exerted during the recovery phase of myocarditis. In this study, 9-week-old male Lewis rats were immunized with cardiac myosin. A plasmid vector expressing mouse IL-10 cDNA (800 mug per rat) was then transferred three times (7, 12 and 17 days after immunization) into the tibialis anterior muscles of the rats by electroporation. Microscopic examination of mast cells was carried out on toluidine blue-stained transverse sections of the mid ventricles. Mouse IL-10 gene transfer significantly reduced mast cell density, cardiac histamine concentration and mast cell growth, and prevented mast cell degranulation. Furthermore, improvement in both myocardial function and the overall condition of the rats was evident from the reduction in the heart weight-to-body weight ratio and inflammatory infiltration as well as improvement in hemodynamic and echocardiographic parameters. These findings suggest that IL-10 gene transfer by electroporation protected against myocarditis via mast cell inhibition.

Suppression of myosin-induced and adoptively transferred myocarditis by prior treatment with complete Freund's adjuvant

BACKGROUND

We evaluated the effect of pretreatment with complete Freund's adjuvant (CFA) on experimentally induced myocarditis concomitant with the assessment of antigen-specific properties of disease-triggering lymphocytes.

METHODS AND RESULTS

Rats pretreated with CFA a week prior to myosin immunization developed a significantly attenuated myocardial inflammation as compared to control-treated animals. Furthermore, prior administration of CFA virtually abolished histological evidence of myocarditis induced by transfer of antimyosin lymphocytes. CFA administered subcutaneously prior to myosin immunization resulted in a significant reduction in lymph node cell reactivity to myosin. Assessment of cultured medium from lymphocytes obtained from CFA-pretreated myosin-immunized rats revealed reduced levels of interferon gamma but an increased production of IL-10, suggesting an induction of a Thl to Th2 switch.

CONCLUSIONS

Thus, CFA treatment suppressed both myosin-induced as well as adoptively transferred myocarditis concomitant with induction of antigen-specific unresponsiveness to myosin and skewing of the immune response in favor of a Th2-dominated profile.

Electric pulse-mediated gene delivery to various animal tissues

Electroporation designates the use of electric pulses to transiently permeabilize the cell membrane. It has been shown that DNA can be transferred to cells through a combined effect of electric pulses causing (1) permeabilization of the cell membrane and (2) an electrophoretic effect on DNA, leading the polyanionic molecule to move toward or across the destabilized membrane. This process is now referred to as DNA electrotransfer or electro gene transfer (EGT). Several studies have shown that EGT can be highly efficient, with low variability both in vitro and in vivo. Furthermore, the area transfected is restricted by the placement of the electrodes, and is thus highly controllable. This has led to an increasing use of the technology to transfer reporter or therapeutic genes to various tissues, as evidenced from the large amount of data accumulated on this new approach for non-viral gene therapy, termed electrogenetherapy (EGT as well). By transfecting cells with a long lifetime, such as muscle fibers, a very long-term expression of genes can be obtained. A great variety of tissues have been transfected successfully, from muscle as the most extensively used, to both soft (e.g., spleen) and hard tissue (e.g., cartilage). It has been shown that therapeutic levels of systemically circulating proteins can be obtained, opening possibilities for using EGT therapeutically. This chapter describes the various aspects of in vivo gene delivery by means of electric pulses, from important issues in methodology to updated results concerning the electrotransfer of reporter and therapeutic genes to different tissues.

DNA electrotransfer: its principles and an updated review of its therapeutic applications

The use of electric pulses to transfect all types of cells is well known and regularly used in vitro for bacteria and eukaryotic cells transformation. Electric pulses can also be delivered in vivo either transcutaneously or with electrodes in direct contact with the tissues. After injection of naked DNA in a tissue, appropriate local electric pulses can result in a very high expression of the transferred genes. This manuscript describes the evolution in the concepts and the various optimization steps that have led to the use of combinations of pulses that fit with the known roles of the electric pulses in DNA electrotransfer, namely cell electropermeabilization and DNA electrophoresis. A summary of the main applications published until now is also reported, restricted to the in vivo preclinical trials using therapeutic genes.

Gene therapy for autoimmune diseases: quo vadis?

Biological therapies using antibodies and cytokines are becoming widespread for the treatment of chronic inflammatory autoimmune diseases. However, these treatments have several limitations - such as expense, the need for repeated injections and unwanted side-effects - that can be overcome by genetic delivery. This review summarizes the ingenuity, sophistication and variety of gene-therapy approaches that have been taken in the design of therapeutic molecules and vectors, the engineering of cells and the regulation of gene expression for the targeting of disease outcome. We focus our attention on multiple sclerosis, type 1 diabetes and rheumatoid arthritis.

Serum levels of interleukin-10 on admission as a prognostic predictor of human fulminant myocarditis

OBJECTIVES

We assessed the significance of serum cytokine levels in patients with fulminant myocarditis.

BACKGROUND

Although many investigations have demonstrated the crucial role of cytokines in the development of myocarditis, it remains uncertain whether serum levels of cytokines enable one to predict the prognosis of human myocarditis, especially concerning cardiogenic shock (CS) requiring a mechanical cardiopulmonary support system (MCSS).

METHODS

We studied 22 consecutive patients with fulminant myocarditis and compared them with 15 patients with acute myocardial infarction (AMI) requiring MCSS. The patients with myocarditis were classified into three groups: eight patients with CS requiring MCSS on admission (group 1); six patients who unexpectedly lapsed into CS requiring MCSS more than two days after catecholamine had been initiated (group 2); and eight patients without MCSS (group 3). Furthermore, 14 patients with myocarditis requiring MCSS were divided into a fatal group (n = 5) and a survival group (n = 9). Biochemical markers, including serum cytokine levels and hemodynamic variables on admission, were analyzed.

RESULTS

Serum levels of interleukin (IL)-10 and tumor necrosis factor-alpha, but not other cytokines, were significantly higher in myocarditis than in AMI. Only serum levels of IL-10 were significantly higher in group 1 and 2 than in group 3 (49.1 +/- 37.5/20.7 +/- 17.6 pg/ml vs. 2.4 +/- 1.1 pg/ml; p = 0.0008/0.0012). Serum IL-10 levels were also significantly higher in the fatal group than in the survival group with myocarditis (74.0 +/- 27.0 pg/ml vs. 16.4 +/- 8.8 pg/ml; p = 0.003).

CONCLUSIONS

Serum IL-10 levels on admission enabled one to predict subsequent CS requiring MCSS and mortality of fulminant myocarditis patients.

Electroporation for gene transfer to skeletal muscles: current status

Naked plasmid DNA can be used to introduce genetic material into a variety of cell types in vivo. However, such gene transfer and expression is generally very low compared with that achieved with viral vectors and so is unsuitable for clinical therapeutic application in most cases. This difference in efficiency has been substantially reduced by the introduction of in vivo electroporation to enhance plasmid delivery to a wide range of tissues including muscle, skin, liver, lung, artery, kidney, retina, cornea, spinal cord, brain, synovium, and tumors. The precise mechanism of in vivo electroporation is uncertain, but appears to involve both electropore formation and an electrophoretic movement of the plasmid DNA. Skeletal muscle is a favored target tissue for three reasons: there is a pressing need to develop effective therapies for muscular dystrophies; skeletal muscle can act as an effective platform for the long-term secretion of therapeutic proteins for systemic distribution; and introduction of DNA vaccines into skeletal muscle promotes strong humoral and cellular immune responses. All of these applications are significantly improved by the application of in vivo electroporation. Importantly, the increased efficiency of plasmid delivery following electroporation is seen in larger species as well as rodents, in contrast to the decreasing efficiencies with increasing body size for simple intramuscular injection of naked plasmid DNA. As this electroporation-enhanced non-viral gene delivery system works well in larger species and avoids the vector-specific immune responses associated with recombinant viruses, the prospects for clinical application are promising.

Cryptic epitope identified in rat and human cardiac myosin S2 region induces myocarditis in the Lewis rat

Myocarditis is a common cause of dilated cardiomyopathy leading to heart failure. Chronic stages of myocarditis may be initiated by autoimmune responses to exposed cardiac Ags after myocyte damage. Cardiac myosin, a heart autoantigen, induced experimental autoimmune myocarditis (EAM) in susceptible animals. Although cardiac myosin-induced myocarditis has been reported in Lewis rats, the main pathogenic epitope has not been identified. Using overlapping synthetic peptides of the S2 region of human cardiac myosin, we identified an amino acid sequence, S2-16 (residues 1052-1076), that induced severe myocarditis in Lewis rats. The myocarditic epitope was localized to a truncated S2-16 peptide (residues 1052-1073), which contained a sequence identical in human and rat cardiac myosin. The S2-16 peptide was not myocarditic for three other strains of rats, in which the lack of myocarditis was accompanied by the absence of strong S2-16-specific lymphocyte responses in vitro. For Lewis rats, S2-16 was characterized as a cryptic epitope of cardiac myosin because it did not recall lymphocyte and Ab responses after immunization with cardiac myosin. Lymphocytes from S2-16 immunized rats recognized not only S2-16, but also peptides in the S2-28 region. Furthermore, peptide S2-28 was the dominant epitope recognized by T cells from cardiac myosin immunized rats. S2-16 was presented by Lewis rat MHC class II molecules, and myocarditis induction was associated with an up-regulation of inflammatory cytokine production. S2-16-induced EAM provides a defined animal model to investigate mechanisms of EAM and modulation of immune responses to prevent autoimmune myocarditis.

A novel method to assay proteins in blood plasma after intravenous injection of plasmid DNA

Gene therapy is expected to lead to new and useful methods to treat diseases. The development of assays to quantitate gene-therapy-derived proteins circulating in blood will be essential to investigate the effects and side effects of the introduced proteins. The purpose of this study is to evaluate whether a protein circulating at trace concentrations in blood can be measured by tagging a peptide corresponding to glucagon residues 19-29 onto its C-terminal end. We constructed plasmids encoding chimeric proteins and transferred them into rats by hydrodynamics-based delivery. When plasmids encoding human IL8-glucagon 19-29 chimeric protein were injected into rats to evaluate the accuracy of this method, there was a high correlation between chimeric proteins measured by an enzyme-linked immunosorbent assay for human IL8 and one by a radioimmunoassay for glucagon. Furthermore, when plasmids coding rat IFN gamma receptor IgG-Fc glucagon 19-29 chimeric protein were injected to evaluate the time course of chimeric proteins in blood plasma, we could calculate the concentrations in blood from 10 microl plasma samples using glucagon 19-29 tag as follows: 2815+/-2318 ng/ml after 4 hours (mean+/-s.D.), 6061+/-2789 ng/ml after 8 hours, 5752+/-2270 ng/ml after 12 hours, 2870+/-1062 ng/ml after one day, 1440+/-334 ng/ml after three days, 1120+/-433 ng/ml after seven days, and 281+/-162 ng/ml after 16 days. Blood sugar levels which might have been increased by glucagon did not increase even at peak chime- ric protein concentrations. These results demonstrate a useful and convenient method to assay gene therapy products circulating in blood using a glucagon 19-29 tagging vector.

Polarity of helper T cell subsets represents disease nature and clinical course of experimental autoimmune myocarditis in rats

The mechanisms of progression, remission and relapse of myocarditis remain unclear. To clarify these mechanisms, we focused on T helper-1 (Th1)/T helper-2 (Th2) subsets balance of peripheral lymphocytes and serum cytokine levels during disease progression in rats with experimental autoimmune myocarditis (EAM). Lewis rats were immunized with cardiac myosin on day 0. Blood samples were collected on days 0, 7, 15, 18, 21, 28, 35, 42, 49 and 56 following immunization. We examined percentages of interferon (IFN)-gamma and/or interleukin (IL)-4 producing cells in stimulated peripheral CD4-positive lymphocytes using flow cytometry analysis. Serum IFN-gamma, IL-2, IL-6 and IL-10 levels were measured by enzyme-linked immunosorbent assay (ELISA). The percentage of Th1/Th2 subsets in EAM on days 0, 15, 28 and 56 were 2.5 +/- 0.5/0.5 +/- 0.1%, 19.4 +/- 3.2/1.6 +/- 0.3%, 2.0 +/- 0.5/22.1 +/- 5.7% and 3.0 +/- 0.4/1.7 +/- 0.3%, respectively. Serum levels of Th1 cytokines, IFN-gamma and IL-2 significantly increased in the acute phase (from day 15-18) and immediately decreased in the early recovery phase. On the other hand, serum levels of Th2 cytokine, IL-10 significantly increased in the early recovery phase (from day 24-30). These results suggest that induction of acute myocarditis might be associated with systemic Th1 dominance, while recovery is related to systemic Th2 polarity. Thus, analysis of Th1/Th2 balance in peripheral T cells may be useful in disease monitoring in patients with myocarditis and postmyocarditic dilated cardiomyopathy.

Vectors for the treatment of autoimmune disease

Gene therapy has been applied in a variety of experimental models of autoimmunity with some success. In this article, we outline recent developments in gene therapy vectors, discuss advantages and disadvantages of each, and highlight their recent applications in autoimmune models. We also consider progress in vector targeting and components for regulating transgene expression, which will both improve gene therapy safety and empower gene therapy to fullfil its potential as a therapeutic modality. In conclusion, we consider candidate vectors that satisfy requirements for application in the principal therapeutic strategies in which gene therapy will be applied to autoimmune conditions.

Dissecting mechanisms of innate and acquired immunity in myocarditis

Inflammation underlies the pathogenesis of some of the most common cardiovascular diseases. Myocarditis is a relevant clinical cause of heart failure, but also provides an excellent laboratory model to study the mechanisms of inflammation leading to heart failure. The availability of different inbred mouse strains for inducing myocarditis using viral or myosin as triggers provides an excellent platform for investigation. The recent use of genetically manipulated mouse models of transgenic overexpression or knockout or knockin targets have provided opportunity to pinpoint specific pathways underlying myocarditis. These pathways include the involvement of both innate and acquired immunity, as well as the role of viral receptors in disease phenotype. These different models also permit the evaluation of therapeutic strategies of candidates for clinical development.

Non-viral gene delivery in skeletal muscle: a protein factory

Ever since the publication of the first reports in 1990 using skeletal muscle as a direct target for expressing foreign transgenes, an avalanche of papers has identified a variety of proteins that can be synthesized and correctly processed by skeletal muscle. The impetus to the development of such applications is not only amelioration of muscle diseases, but also a range of therapeutic applications, from immunization to delivery of therapeutic proteins, such as clotting factors and hormones. Although the most efficient way of introducing transgenes into muscle fibres has been by a variety of recombinant viral vectors, there are potential benefits in the use of non-viral vectors. In this review we assess the recent advances in construction and delivery of naked plasmid DNA to skeletal muscle and highlight the options available for further improvements to raise efficiency to therapeutic levels.

Interleukin-10 expression after intramuscular DNA electrotransfer: kinetic studies

Transfected muscle can be used as a secreting tissue for therapeutic proteins. Skeletal muscle transfection is increased by suitable electric pulse application (electrotransfer). We and others had shown that electrotransfer of interleukin-10 encoding plasmid is an effective strategy in animal models of chronic diseases such as myocarditis, atherosclerosis, or rheumatoid arthritis. In the present work, we have studied murine interleukin-10 production and secretion after i.m. electrotransfer. In immunocompetent mice, serum and muscle mIL-10 levels were enhanced by electrotransfer. Serum mIL-10 concentration reached rapidly a peak level 2 days after electrotransfer. It then decreased to background at day 14. Muscle mIL-10 mRNA and protein remained more stable, being detectable up to 84 days after electrotransfer. A boost reinjection led to similar high level of circulating mIL-10. The fast decrease of serum mIL-10 was not observed in SCID mice.

In vivo plasmid DNA electrotransfer

In vivo electrotransfer is a physical technique for gene delivery in various mammalian tissues, which involves the injection of plasmid DNA into a target tissue and administration of an electric field. Its ease of performance, as well as recent understanding of its mechanism and applications to different mammalian tissues such as skeletal muscle, liver, brain and tumors, makes it a powerful technique. It could be used in gene therapy and as a laboratory tool to study gene functions.

Applications of plasmid electrotransfer

The use of electric pulses to transfect cells has recently been extended to show the utility of this procedure in vivo. Electrotransfer has been performed in vivo on several tissue types including skin, blood vessels, liver, tumor, muscle, cornea, brain and spleen. The most widely targeted tissue has been skeletal muscle. In addition to its potential use in gene therapy, in vivo DNA electrotransfer is also, because of its simplicity, a powerful laboratory tool to study in vivo gene expression and function in a given tissue. Many published studies have now shown that plasmid electrotransfer can lead to a long-lasting therapeutic effect in various pathologies, such as cancer, blood disease, or muscle ischemia. The future potential for this gene therapy approach will include delivery for both local action or distal effect by secretion of the transgenic proteins in the circulation.