Secreted Phospholipase A2-IIA Modulates Transdifferentiation of Cardiac Fibroblast through EGFR Transactivation: An Inflammation-Fibrosis Link

TGF-α/EGFR signaling promotes lipopolysaccharide-induced abnormal elastin deposition and alveolar simplification

Bronchopulmonary dysplasia (BPD) is characterized by shortened secondary septa and fewer, larger alveoli. Elastin deposition to the distal tips of the secondary septa is critical for elongation of the secondary septa. Alveolar myofibroblasts, which are thought to migrate to the septal tips during alveolarization, are mainly responsible for elastin production and deposition. Antenatal exposure to inflammation induces abnormal elastin deposition, thereby increasing the risk of developing BPD. Here, we found that lipopolysaccharide (LPS) significantly increased the expression of transforming growth factor-α (TGF-α) in an LPS-induced rat model of BPD and in LPS-treated human pulmonary epithelial cells (BEAS-2B). In addition, in vitro experiments suggested that LPS upregulated TGF-α expression via toll-like receptor 4 (TLR4)/tumor necrosis factor α-converting enzyme (TACE) signaling. Increased TGF-α levels via its receptor epidermal growth factor receptor (EGFR)-induced lysyl oxidase (LOX) overactivation and cell division cycle 42 (Cdc42) activity inhibition of myofibroblasts. Similarly, in vivo LOX overactivation and inhibition of Cdc42 activity were observed in the lungs of LPS-exposed pups. LOX overactivation led to abnormal elastin deposition, and inhibition of Cdc42 activity disturbed the directional migration of myofibroblasts and disrupted elastin localization. Most importantly, the EGFR inhibitor erlotinib partially rescued LOX overactivation and Cdc42 activity inhibition, and improved elastin deposition and alveolar development in antenatal LPS-treated rats. Taken together, our data suggest that TGF-α/EGFR signaling is critically involved in the regulation of elastin deposition and represents a novel therapeutic target.

SOX9 Induces Orbital Fibroblast Activation in Thyroid Eye Disease Via MAPK/ERK1/2 Pathway

Purpose

To evaluate the expression of sry-box transcription factor 9 (SOX9) in orbital fibroblasts (OFs) of thyroid eye disease (TED) and to find its potential role and underlying mechanism in orbital fibrosis.

Methods

OFs were cultured from orbital connective tissues obtained from patients with TED (n = 10) and healthy controls (n = 6). SOX9 was depleted by small interfering RNA or overexpressed through lentivirus transduction in OFs. Fibroblast contractile activity was measured by collagen gel contraction assay and proliferation was examined by EdU assay. Transcriptomic changes were assessed by RNA sequencing.

Results

The mRNA and protein levels of SOX9 were significantly higher in OFs cultured from patients with TED than those from healthy controls. Extracellular matrix-related genes were down-regulated by SOX9 knockdown and up-regulated by SOX9 overexpression in TED-OFs. SOX9 knockdown significantly decrease the contraction and the antiapoptotic ability of OFs, whereas the overexpression of SOX9 increased the ability of transformation, migration, and proliferation of OFs. SOX9 knockdown suppressed the expression of phosphorylated ERK1/2, whereas its overexpression showed the opposite effect. Epidermal growth factor receptor (EGFR) is one of the notably down-regulated genes screened out by RNA sequencing. Chromatin immunoprecipitation-qPCR demonstrated SOX9 binding to the EGFR promoter.

Conclusions

A high expression of SOX9 was found in TED-OFs. SOX9 can activate OFs via MAPK/ERK1/2 signaling pathway, which in turn promotes proliferation and differentiation of OFs. EGFR was a downstream target gene of SOX9. SOX9/EGFR can be considered as therapeutic targets for the treatment of orbital fibrosis in TED.

Fibulin7 Mediated Pathological Cardiac Remodeling through EGFR Binding and EGFR-Dependent FAK/AKT Signaling Activation

Adverse remodeling after myocardial infarction (MI) result in heart failure and sudden cardiac death. Fibulin7 (FBLN7) is an adhesion protein excreted into the extracellular matrix that functions in multiple biological processes. However, whether and how FBLN7 affects post-MI cardiac remodeling remains unclear. Here, the authors identify FBLN7 as a critical profibrotic regulator of adverse cardiac remodeling. They observe significantly upregulated serum FBLN7 levels in MI patients with left ventricular remodeling compared to those without MI. Microarray dataset analysis reveal FBLN7 is upregulated in human heart samples from patients with dilated and hypertrophic cardiomyopathy compared with non-failing hearts. The authors demonstrate that FBLN7 deletion attenuated post-MI cardiac remodeling, leading to better cardiac function and reduced myocardial fibrosis, whereas overexpression of FBLN7 results in the opposite effects. Mechanistically, FBLN7 binds to the epidermal growth factor receptor (EGFR) through its EGF-like domain, together with the EGF-like calcium-binding domain, and induces EGFR autophosphorylation at tyrosine (Y) 1068 and Y1173, which activates downstream focal adhesion kinase/AKT signaling, thereby leading to fibroblast-to-myofibroblast transdifferentiation. In addition, FBLN7-EGFR mediates this signal transduction, and the fibrotic response is effectively suppressed by the inhibition of EGFR activity. Taken together, FBLN7 plays an important role in cardiac remodeling and fibrosis after MI.

Single-Cell Analysis of ADSC Interactions with Fibroblasts and Endothelial Cells in Scleroderma Skin

Adipose-derived stem cells (ADSCs) as part of autologous fat grafting have anti-fibrotic and anti-inflammatory effects, but the exact mechanisms of action remain unknown. By simulating the interaction of ADSCs with fibroblasts and endothelial cells (EC) from scleroderma (SSc) skin in silico, we aim to unravel these mechanisms. Publicly available single-cell RNA sequencing data from the stromal vascular fraction of 3 lean patients and biopsies from the skin of 10 control and 12 patients with SSc were obtained from the GEO and analysed using R and Seurat. Differentially expressed genes were used to compare the fibroblast and EC transcriptome between controls and SSc. GO and KEGG functional enrichment was performed. Ligand-receptor interactions of ADSCs with fibroblasts and ECs were explored with LIANA. Pro-inflammatory and extracellular matrix (ECM) interacting fibroblasts were identified in SSc. Arterial, capillary, venous and lymphatic ECs showed a pro-fibrotic and pro-inflammatory transcriptome. Most interactions with both cell types were based on ECM proteins. Differential interactions identified included NTN1, VEGFD, MMP2, FGF2, and FNDC5. The ADSC secretome may disrupt vascular and perivascular inflammation hubs in scleroderma by promoting angiogenesis and especially lymphangiogenesis. Key phenomena observed after fat grafting remain unexplained, including modulation of fibroblast behaviour.

Cellular Distribution of Secreted Phospholipase A2 in Lungs of IPF Patients and Its Inhibition in Bleomycin-Induced Pulmonary Fibrosis in Mice

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease with a very poor prognosis as it has a 2.5 to 5 years mean survival after proper diagnosis. Even nintedanib and pirfenidone cannot halt the progression, though they slow the progression of IPF. Hence, there is a need to understand the novel pathophysiology. Phospholipase A2 (PLA2) could be the ideal candidate to study in IPF, as they have a role in both inflammation and fibrosis. In the present study, we have shown the expression profile of various secretory Phospholipase A2 (PLA2) isoforms by analyzing publicly available transcriptome data of single cells from the lungs of healthy individuals and IPF patients. Among 11 members of sPLA2, PLA2G2A is found to be increased in the fibroblasts and mesothelial cells while PLA2G5 is found to be increased in the fibroblasts of IPF patients. We identified a subset of fibroblasts expressing high PLA2G2A with moderate expression of PLA2G5 and which are specific to IPF only; we named it as PLA2G2A+ IPF fibroblast. Pathway analysis revealed that these PLA2G2A+ IPF fibroblast have upregulation of both inflammatory and fibrosis-related pathways like the TGF-β signaling pathway, IL-17 signaling, the arachidonic acid metabolism pathway and ECM-receptor interaction. In addition to this, we found elevated levels of sPLA2-IIA in plasma samples of IPF patients in our cohort. PLA2G3, PLA2G10 and PLA2G12B are found in to be increased in certain epithelial cells of IPF patients. Thus, these findings indicate that these five isoforms have a disease-dominant role along with innate immune roles as these isoforms are found predominantly in structural cells of IPF patients. Further, we have targeted sPLA2 in mice model of bleomycin-induced lung fibrosis by pBPB, a known sPLA2 inhibitor. pBPB treatment attenuated lung fibrosis induced by bleomycin along with a reduction in TGF-β and deposition of extracellular matrix in lung. Thus, these findings indicate that these sPLA2 isoforms especially PLA2G2A may serve as a therapeutic target in lung fibrosis.

Secretory Phospholipases A2, from Snakebite Envenoming to a Myriad of Inflammation Associated Human Diseases-What Is the Secret of Their Activity?

Secreted phospholipases of type A2 (sPLA2s) are proteins of 14-16 kDa present in mammals in different forms and at different body sites. They are involved in lipid transformation processes, and consequently in various immune, inflammatory, and metabolic processes. sPLA2s are also major components of snake venoms, endowed with various toxic and pharmacological properties. The activity of sPLA2s is not limited to the enzymatic one but, through interaction with different types of molecules, they exert other activities that are still little known and explored, both outside and inside the cells, as they can be endocytosed. The aim of this review is to analyze three features of sPLA2s, yet under-explored, knowledge of which could be crucial to understanding the activity of these proteins. The first feature is their disulphide bridge pattern, which has always been considered immutable and necessary for their stability, but which might instead be modulable. The second characteristic is their ability to undergo various post-translational modifications that would control their interaction with other molecules. The third feature is their ability to participate in active molecular condensates both on the surface and within the cell. Finally, the implications of these features in the design of anti-inflammatory drugs are discussed.

Lysine demethylase 3A is a positive regulator of cardiac myofibroblast transdifferentiation that increases Smad3 phosphorylation following transforming growth factor beta1 stimulation

BACKGROUND

The epigenetic modifier molecule lysine demethylase 3A (KDM3A) has been shown to help ameliorate cardiovascular diseases, but its effect on cardiac fibroblasts (CFs) remains unclear.

METHODS AND RESULTS

We designed gain- and loss-of-function experiments to investigate the biological functions of KDM3A in CFs. Moreover, we used SIS3-HCl (a specific inhibitor of p-Smad3) to explore the underlying mechanism. Cell viability and migration were verified by CCK-8 and cell migration experiments, respectively, and the degree of fibrosis was measured by Western blot analysis. Our data revealed that KDM3A enhanced the proliferation and migration of CFs and increased the fibroblast-to-myofibroblast transition while enabling the Smad3 phosphorylation response to transforming growth factor beta1 (TGFβ1) stimulation. However, these effects were abolished by SIS3-HCl. Furthermore, KDM3A inhibition obviously protected against cardiac myofibroblast transdifferentiation under TGFβ1 stimulation.

CONCLUSIONS

KDM3A may act as a novel regulator of cardiac myofibroblast transdifferentiation through its ability to modulate the phosphorylation of Smad3 following TGFβ1 stimulation.

Nimotuzumab for COVID-19: case series

Background: In COVID-19, EGFR production is upregulated in the alveolar epithelial cells. EGFR overexpression further activates STAT-3 and increases lung pathology. The EGFR pathway is also one of the major nodes in pulmonary fibrosis. Methods: Nimotuzumab, a humanized anti-EGFR antibody, was used to treat three patients with severe or moderate COVID-19. The antibody was administered in combination with other drugs included in the national COVID-19 protocol. Results: Nimotuzumab was well tolerated. IL-6 decreased from the first antibody infusion. Clinical symptoms significantly improved after nimotuzumab administration, and the CT scans at discharge showed major resolution of the lung lesions and no signs of fibrosis. Conclusion: Safe anti-EGFR antibodies like nimotuzumab may modulate COVID-19-associated hyperinflammation and prevent fibrosis. Clinical Trial Registration: RPCEC00000369 (RPCEC rpcec.sld.cu).

Management of inflammation in cardiovascular diseases

Cardiovascular disease is the leading cause of morbidity and mortality world-wide. Recently, the role of inflammation in the progression of diseases has significantly attracted considerable attention. In addition, various comorbidities, including diabetes, obesity, etc. exacerbate inflammation in the cardiovascular system, which ultimately leads to heart failure. Furthermore, cytokines released from specialized immune cells are key mediators of cardiac inflammation. Here, in this review article, we focused on the role of selected immune cells and cytokines (both pro-inflammatory and anti-inflammatory) in the regulation of cardiac inflammation and ultimately in cardiovascular diseases. While IL-1β, IL-6, TNFα, and IFNγ are associated with cardiac inflammation; IL-10, TGFβ, etc. are associated with resolution of inflammation and cardiac repair. IL-10 reduces cardiovascular inflammation and protects the cardiovascular system via interaction with SMAD2, p53, HuR, miR-375 and miR-21 pathway. In addition, we also highlighted recent advancements in the management of cardiac inflammation, including clinical trials of anti-inflammatory molecules to alleviate cardiovascular diseases.

Crucial Role of Mammalian Glutaredoxin 3 in Cardiac Energy Metabolism in Diet-induced Obese Mice Revealed by Transcriptome Analysis

Obesity is often associated with metabolic dysregulation and oxidative stress with the latter serving as a possible unifying link between obesity and cardiovascular complications. Glutaredoxins (Grxs) comprise one of the major antioxidant systems in the heart. Although Grx3 has been shown to act as an endogenous negative regulator of cardiac hypertrophy and heart failure, its metabolic impact on cardiac function in diet-induced obese (DIO) mice remains largely unknown. In the present study, analysis of Grx3 expression indicated that Grx3 protein levels, but not mRNA levels, were significantly increased in the hearts of DIO mice. Cardiac-specific Grx3 deletion (Grx3 CKO) mice were viable and grew indistinguishably from their littermates after being fed a high fat diet (HFD) for one month, starting at 2 months of age. After being fed with a HFD for 8 months (starting at 2 months of age); however, Grx3 CKO DIO mice displayed left ventricular systolic dysfunction with a significant decrease in ejection fraction and fractional shortening that was associated with heart failure. ROS production was significantly increased in Grx3 CKO DIO cardiomyocytes compared to control cells. Gene expression analysis revealed a significant decline in the level of transcripts corresponding to genes associated with processes such as fatty acid uptake, mitochondrial fatty acid transport and oxidation, and citrate cycle in Grx3 CKO DIO mice compared to DIO controls. In contrast, an increase in the level of transcripts corresponding to genes associated with glucose uptake and utilization were found in Grx3 CKO DIO mice compared to DIO controls. Taken together, these findings indicate that Grx3 may play a critical role in redox balance and as a metabolic switch in cardiomyocytes contributing to the development and progression of heart failure.

Research Progress of Therapeutic Enzymes and Their Derivatives: Based on Herbal Medicinal Products in Rheumatoid Arthritis

Rheumatoid arthritis (RA) acts as one of the most common, agnogenic and chronic inflammatory-autoimmune disorder which is characterized by persistent synovitis, cartilage destruction, and joint deformities, leads to a wide range of disabilities, and increased mortality, thus imposing enormous burdens. Several drugs with anti-inflammatory and immunomodulatory properties such as celecoxib, diclofenac and methotrexate are being selected as conventional drugs in the allopathic system of medicine for the treatment of RA in clinic. However, there are some serious side effects more or less when using these drugs because of their short poor bioavailability and biological half-life for a long time. These shortcomings greatly promote the exploration and application of new low- or no-toxicity drugs for treating the RA. Meanwhile, a growing number of studies demonstrate that several herbs present certain anti-inflammatory and anti-arthritic activities through different enzymes and their derivatives, which indicate that they are promising therapeutic strategies when targeting these mediators based on herbal medicinal products in RA research. This review article summarizes the roles of the main enzymes and their derivatives during the pathogenesis of RA, and clearly clarifies the explicit and potential targeted actions of herbal medicinal products that have anti-RA activity. Our review provides timely and critical reference for the scientific rationale use of herbal medicinal products, with the increasing basic research and clinical application of herbal medicinal products by patients with RA.

Cells in Cardiovascular Disease: Using Diversity to Confront Adversity

The present Special Issue on "Cells in Cardiovascular Disease" wants to offer a general overview of current cardiovascular research and illustrate how advances in the molecular characterization at the cellular level are providing unique insights into pathologies of the circulatory system [...].

Group V secreted phospholipase A2 plays a protective role against aortic dissection

Aortic dissection is a life-threatening aortopathy involving separation of the aortic wall, whose underlying mechanisms are still incompletely understood. Epidemiological evidence suggests that unsaturated fatty acids improve cardiovascular health. Here, using quantitative RT-PCR, histological analyses, magnetic cell sorting and flow cytometry assays, and MS-based lipidomics, we show that the activity of a lipid-metabolizing enzyme, secreted phospholipase A₂ group V (sPLA₂-V), protects against aortic dissection by endogenously mobilizing vasoprotective lipids. Global and endothelial cell-specific sPLA₂-V-deficient mice frequently developed aortic dissection shortly after infusion of angiotensin II (AT-II). We observed that in the AT-II-treated aorta, endothelial sPLA₂-V mobilized oleic and linoleic acids, which attenuated endoplasmic reticulum stress, increased the expression of lysyl oxidase, and thereby stabilized the extracellular matrix in the aorta. Of note, dietary supplementation with oleic or linoleic acid reversed the increased susceptibility of sPLA₂-V-deficient mice to aortic dissection. These findings reveal an unexplored functional link between sPLA₂-driven phospholipid metabolism and aortic stability, possibly contributing to the development of improved diagnostic and/or therapeutic strategies for preventing aortic dissection.