An mTORC1-Dependent Mouse Model for Cardiac Sarcoidosis

[Position paper of the Austrian Society for Rheumatology and the Austrian Society for Pneumology on the diagnosis and treatment of sarcoidosis 2024]

In many cases sarcoidosis is a multisystemic disease that requires interdisciplinary medical cooperation in the diagnostics, treatment and medical care during follow-up. Due to the often chronic course, it is of utmost importance to include patients with their priorities and wishes at an early stage and extensively in disease management and to establish a shared decision making whenever possible. In the process of writing this joint position paper, the expert group on interstitial and orphan lung diseases of the Austrian Society for Pulmonology and the working group on rheumatological lung disorders of the Austrian Society for Rheumatology and Rehabilitation sought to include patient advocacy groups as well as experts for rare organ manifestations of sarcoidosis. This position paper is not only meant to reflect current scientific and clinical standards but should also focus the national expertise and by networking and exchange to be a first step to strengthen cooperation between stakeholders to ultimately improve care for patients with sarcoidosis.

Development of a Mouse Cardiac Sarcoidosis Model Using Carbon Nanotubes

Sarcoidosis, a granulomatous disorder of unknown etiology affecting multiple organs. It is often a benign disease but can have significant morbidity and mortality when the heart is involved (often presenting with clinical manifestations such as conduction irregularities and heart failure). This study addresses a critical gap in cardiac sarcoidosis (CS) research by developing a robust animal model. The absence of a reliable animal model for cardiac sarcoidosis is a significant obstacle in advancing understanding and treatment of this condition. The proposed model utilizes carbon nanotube injection and transverse aortic constriction as stressors. Intramyocardial injection of carbon nanotubes induces histiocytes typical of sarcoid granulomas in the heart but shows limited effects on fibrosis or cardiac function. Priming the immune system with transverse aortic constriction prior to intramyocardial injection of carbon nanotubes enhances cardiac fibrosis, diminishes cardiac function, and impairs cardiac conduction. This novel, easily executable model may serve as a valuable tool for disease profiling, biomarker identification, and therapeutic exploration.

Study on the mechanisms and Pharmacodynamic substances of Lian-Gui-Ning-Xin-Tang on Arrhythmia Therapy based on Pharmacodynamic-Pharmacokinetic associations

Background

The Chinese herbal compound Lian-Gui-Ning-Xin-Tang (LGNXT), composed of 9 herbs, has a significant antiarrhythmic effect. Previous studies have confirmed that preventing intracellular Ca2+ overload and maintaining intracellular Ca2+ homeostasis may be the important antiarrhythmic mechanisms of LGNXT. Recent studies are focused on elucidating the mechanisms and pharmacodynamic substances of LGNXT.

Purpose

1) To investigate the antiarrhythmic mechanisms of LGNXT; 2) to explore the association of pharmacodynamics (PD) and pharmacokinetics (PK) of the potential pharmacodynamic substances in LGNXT to further verify the mechanisms of action.

Methods

First, pharmacodynamic studies were conducted to determine the effect of LGNXT in arrhythmia at the electrophysiological, molecular, and tissue levels, and the "effect-time" relationship of LGNXT was further proposed. Next, an HPLC-MS/MS method was established to identify the "dose-time" relationship of the 9 potential compounds. Combining the "effect-time" and "dose-time" curves, the active ingredients closely related to the inhibition of inflammation, oxidative stress, and energy metabolism were identified to further verify the mechanisms and pharmacodynamic substances of LGNXT.

Results

Pretreatment with LGNXT could delay the occurrence of arrhythmias and reduce their duration and severity. LGNXT exerted antiarrhythmic effects by inhibiting MDA, LPO, IL-6, and cAMP; restoring Cx43 coupling function; and upregulating SOD, Ca2+-ATPase, and Na+-K+-ATPase levels. PK-PD association showed that nobiletin, methylophiopogonanone A, trigonelline, cinnamic acid, liquiritin, dehydropolisic acid, berberine, and puerarin were the main pharmacodynamic substances responsible for inhibiting the inflammatory response in arrhythmia. Methylophiopogonanone A, dehydropalingic acid, nobiletin, trigonelline, berberine, and puerarin in LGNXT exerted antiarrhythmic effects by inhibiting oxidative stress. Dehydropalingic acid, berberine, cinnamic acid, liquiritin, puerarin, trigonelline, methylophiopogonanone A, nobiletin, and tetrahydropalmatine exerted antiarrhythmic effects by inhibiting the energy-metabolism process.

Conclusions

LGNXT had a positive intervention effect on arrhythmias, especially ventricular tachyarrhythmias, which could inhibit inflammation, oxidative stress, and energy metabolism; positively stabilize the structure, and remodify the function of myocardial cell membranes. Additionally, the PD-PK association study revealed that methylophiopogonanone A, berberine, trigonelline, liquiritin, puerarin, tetrahydropalmatine, nobiletin, dehydropachymic acid, and cinnamic acid directly targeted inflammation, oxidative stress, and energy metabolism, which could be considered the pharmacodynamic substances of LGNXT. Thus, the antiarrhythmic mechanisms of LGNXT were further elucidated.

Clinical Characteristics and Mechanisms of Acute Myocarditis

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT05335928.

Inhibition of the rapamycin-insensitive mTORC1 /4E-BP1 axis attenuates TGF-β1-induced fibrotic response in human Tenon's fibroblasts

Subconjunctival fibrosis is the major cause of failure in both conventional and modern minimally invasive glaucoma surgeries (MIGSs) with subconjunctival filtration. The search for safe and effective anti-fibrotic agents is critical for improving long-term surgical outcomes. In this study, we investigated the effect of inhibiting the rapamycin-insensitive mTORC1/4E-BP1 axis on the transforming growth factor-beta 1(TGF-β1)-induced fibrotic responses in human Tenon's fibroblasts (HTFs), as well as in a rat model of glaucoma filtration surgery (GFS). Primary cultured HTFs were treated with 3 ng/mL TGF-β1 for 24 h, followed by treatment with 10 μM CZ415 for additional 24 h. Rapamycin (10 μM) was utilized as a control for mTORC1/4E-BP1 signaling insensitivity. The expression levels of fibrosis-associated molecules were measured using quantitative real-time PCR, Western blotting, and immunofluorescence analysis. Cell migration was assessed through the scratch wound assay. Additionally, a rat model of GFS was employed to evaluate the anti-fibrotic effect of CZ415 in vivo. Our findings indicated that both rapamycin and CZ415 treatment significantly reduced the TGF-β1-induced cell proliferation, migration, and the expression of pro-fibrotic factors in HTFs. CZ415 also more effectively inhibited TGF-β1-mediated collagen synthesis in HTFs compared to rapamycin. Activation of mTORC1/4E-BP signaling following TGF-β1 exposure was highly suppressed by CZ415 but was only modestly inhibited by rapamycin. Furthermore, CZ415 was found to decrease subconjunctival collagen deposition in rats post GFS. Our results suggest that rapamycin-insensitive mTORC1/4E-BP1 signaling plays a critical role in TGF-β1-driven collagen synthesis in HTFs. This study demonstrated that inhibition of the mTORC1/4E-BP1 axis offers superior anti-fibrotic efficacy compared to rapamycin and represents a promising target for improving the success rate of both traditional and modern GFSs.

Autoimmune Myocarditis, Old Dogs and New Tricks

Autoimmunity significantly contributes to the pathogenesis of myocarditis, underscored by its increased frequency in autoimmune diseases such as systemic lupus erythematosus and polymyositis. Even in cases of myocarditis caused by viral infections, dysregulated immune responses contribute to pathogenesis. However, whether triggered by existing autoimmune conditions or viral infections, the precise antigens and immunologic pathways driving myocarditis remain incompletely understood. The emergence of myocarditis associated with immune checkpoint inhibitor therapy, commonly used for treating cancer, has afforded an opportunity to understand autoimmune mechanisms in myocarditis, with autoreactive T cells specific for cardiac myosin playing a pivotal role. Despite their self-antigen recognition, cardiac myosin-specific T cells can be present in healthy individuals due to bypassing the thymic selection stage. In recent studies, novel modalities in suppressing the activity of pathogenic T cells including cardiac myosin-specific T cells have proven effective in treating autoimmune myocarditis. This review offers an overview of the current understanding of heart antigens, autoantibodies, and immune cells as the autoimmune mechanisms underlying various forms of myocarditis, along with the latest updates on clinical management and prospects for future research.

Sarcoidosis immunopathogenesis - a new concept of maladaptive trained immunity

Sarcoidosis is a chronic immune disease of unknown origin for which we still lack an immunological framework unifying causal agents, host factors, and natural history of disease. Here, we discuss the initial triggers of disease, and how myeloid cells drive granuloma formation and contribute to immunopathogenesis. We highlight recent advances in our understanding of innate immune memory and propose the hypothesis that maladaptive innate immune training connects previous environmental exposure to granuloma maintenance and expansion. Lastly, we consider how this hypothesis may open novel therapeutic avenues, while corticosteroids remain the front-line treatment.

The immunopathogenesis of sarcoidosis

Sarcoidosis is a granulomatous multiorgan disease, thought to result from exposure to yet unidentified antigens in genetically susceptible individuals. The exaggerated inflammatory response that leads to granuloma formation is highly complex and involves the innate and adaptive immune system. Consecutive immunological studies using advanced technology have increased our understanding of aberrantly activated immune cells, mediators and pathways that influence the formation, maintenance and resolution of granulomas. Over the years, it has become increasingly clear that disease immunopathogenesis can only be understood if the clinical heterogeneity of sarcoidosis is taken into consideration, along with the distribution of immune cells in peripheral blood and involved organs. Most studies offer an immunological snapshot during disease course, while the cellular composition of both the circulation and tissue microenvironment may change over time. Despite these challenges, novel insights on the role of the immune system are continuously published, thus bringing the field forward. This review highlights current knowledge on the innate and adaptive immune responses involved in sarcoidosis pathogenesis, as well as the pathways involved in non-resolving disease and fibrosis development. Additionally, we describe proposed immunological mechanisms responsible for drug-induced sarcoid like reactions. Although many aspects of disease immunopathogenesis remain to be unraveled, the identification of crucial immune reactions in sarcoidosis may help identify new treatment targets. We therefore also discuss potential therapies and future strategies based on the latest immunological findings.

Application of laboratory models for sarcoidosis research

This manuscript will review the implications and applications of sarcoidosis models towards advancing our understanding of sarcoidosis disease mechanisms, identification of biomarkers, and preclinical testing of novel therapies. Emerging disease models and innovative research tools will also be considered.