SH2 domain-containing protein tyrosine phosphatase-2 (SHP-2) prevents cardiac remodeling after myocardial infarction through ERK/SMAD signaling pathway

sFgl2 gene-modified MSCs regulate the differentiation of CD4+ T cells in the treatment of autoimmune hepatitis

BACKGROUND

Autoimmune hepatitis (AIH) is a T-cell-mediated autoimmune liver disease that can lead to liver injury and has a poor long-term prognosis. Mesenchymal stromal cells (MSCs) have immunosuppressive effects and can treat AIH. CD4+ T cells express the unique inhibitory Fcγ receptor (FcγRIIB), which is the only receptor for the immunosuppressive factor soluble fibrinogen-like protein 2 (sFgl2). This study aimed to examine the therapeutic effect of sFgl2 gene-modified MSCs (sFgl2-MSCs) on AIH.

METHODS

MSCs were obtained from the inguinal fat of mice and cocultured with CD4+ T cells sorted from mouse spleens. FcγRIIB expression on CD4+ T cells was determined by flow cytometry. sFgl2 expression in MSCs transfected with lentiviral vectors carrying the Fgl2 gene and a green fluorescent protein-encoding sequence was determined by enzyme-linked immunosorbent assay. The percentages of Th1 cells Th17 cells and regulatory T cells (Tregs) were determined by flow cytometry And the levels of p-SHP2 and p-SMAD2/3 were detected by Western blotting after the cells were cocultured with MSCs for 72 h. After locating MSCs by in vivo imaging Con A-induced experimental AIH mice were randomly divided into 4 groups and administered different treatments. After 24 h histopathological scores liver function and cytokine levels were examined and the proportions of CD4+ T cells CD8+ T cells Tregs Th17 cells and Th1 cells in the spleen and liver were determined by flow cytometry. In addition immunohistochemical staining was used to detect the liver infiltration of T-bet-, Foxp3- and RORγ-positive cells.

RESULTS

FcγRIIB expression on CD4+ T cells was upregulated after coculture with MSCs. After coculture with sFgl2-MSCs, the proportion of Tregs among CD4+ T cells increased, the proportion of Th17 and Th1 cells decreased, and the levels of p-SHP2 and p-SMAD2/3 increased. In vivo, sFgl2-MSCs significantly improved liver function, decreased liver necrosis area, decreased tumor necrosis factor-α, interleukin (IL)-1β and IL-6 expression, increased IL-10 expression, reduced liver infiltration of CD4+ T and CD8+ T cells, increased the proportion of Tregs and reduced the proportions of Th17 and Th1 cells in mice.

CONCLUSION

By promoting Tregs differentiation and inhibiting Th17 and Th1 cell differentiation, sFgl2 gene-modified MSCs have a more powerful therapeutic effect on Con A-induced experimental AIH and may represent a strategy for the clinical treatment of AIH.

Comparative Analysis of Heart Regeneration: Searching for the Key to Heal the Heart-Part II: Molecular Mechanisms of Cardiac Regeneration

Cardiovascular diseases are the leading cause of death worldwide, among which ischemic heart disease is the most representative. Myocardial infarction results from occlusion of a coronary artery, which leads to an insufficient blood supply to the myocardium. As it is well known, the massive loss of cardiomyocytes cannot be solved due the limited regenerative ability of the adult mammalian hearts. In contrast, some lower vertebrate species can regenerate the heart after an injury; their study has disclosed some of the involved cell types, molecular mechanisms and signaling pathways during the regenerative process. In this 'two parts' review, we discuss the current state-of-the-art of the main response to achieve heart regeneration, where several processes are involved and essential for cardiac regeneration.

Post-myocardial infarction fibrosis: Pathophysiology, examination, and intervention

Cardiac fibrosis plays an indispensable role in cardiac tissue homeostasis and repair after myocardial infarction (MI). The cardiac fibroblast-to-myofibroblast differentiation and extracellular matrix collagen deposition are the hallmarks of cardiac fibrosis, which are modulated by multiple signaling pathways and various types of cells in time-dependent manners. Our understanding of the development of cardiac fibrosis after MI has evolved in basic and clinical researches, and the regulation of fibrotic remodeling may facilitate novel diagnostic and therapeutic strategies, and finally improve outcomes. Here, we aim to elaborate pathophysiology, examination and intervention of cardiac fibrosis after MI.

G Protein-Coupled Receptor Kinase 2 as Novel Therapeutic Target in Fibrotic Diseases

G protein-coupled receptor kinase 2 (GRK2), an important subtype of GRKs, specifically phosphorylates agonist-activated G protein-coupled receptors (GPCRs). Besides, current research confirms that it participates in multiple regulation of diverse cells via a non-phosphorylated pathway, including interacting with various non-receptor substrates and binding partners. Fibrosis is a common pathophysiological phenomenon in the repair process of many tissues due to various pathogenic factors such as inflammation, injury, drugs, etc. The characteristics of fibrosis are the activation of fibroblasts leading to myofibroblast proliferation and differentiation, subsequent aggerate excessive deposition of extracellular matrix (ECM). Then, a positive feedback loop is occurred between tissue stiffness caused by ECM and fibroblasts, ultimately resulting in distortion of organ architecture and function. At present, GRK2, which has been described as a multifunctional protein, regulates copious signaling pathways under pathophysiological conditions correlated with fibrotic diseases. Along with GRK2-mediated regulation, there are diverse effects on the growth and apoptosis of different cells, inflammatory response and deposition of ECM, which are essential in organ fibrosis progression. This review is to highlight the relationship between GRK2 and fibrotic diseases based on recent research. It is becoming more convincing that GRK2 could be considered as a potential therapeutic target in many fibrotic diseases.

Positive feedback regulation between USP15 and ERK2 inhibits osteoarthritis progression through TGF-β/SMAD2 signaling

Background

The transforming growth factor-β (TGF-β) signaling pathway plays an essential role in maintaining homeostasis in joints affected by osteoarthritis (OA). However, the specific mechanism of non-SMAD and classical SMAD signaling interactions is still unclear, which needs to be further explored.

Methods

In ATDC5 cells, USP15 overexpression and knockout were performed using the transfected lentivirus USP15 and Crispr/Cas9. Western blotting and immunofluorescence staining were used to test p-SMAD2 and cartilage phenotype-related molecular markers. In rat OA models, immunohistochemistry, hematoxylin and eosin (HE)/Safranin-O fast green staining, and histology were used to examine the regulatory activity of USP15 in TGF-β/SMAD2 signaling and the cartilage phenotype. Then, ERK2 overexpression and knockout were performed. The expressions of USP15, p-SMAD2, and the cartilage phenotype were evaluated in vitro and in vivo. To address whether USP15 is required for ERK2 and TGF-β/SMAD2 signaling, we performed rescue experiments in vitro and in vivo. Immunoprecipitation and deubiquitination assays were used to examine whether USP15 could bind to ERK2 and affect the deubiquitination of ERK2. Finally, whether USP15 regulates the level of p-ERK1/2 was evaluated by western blotting, immunofluorescence staining, and immunohistochemistry in vitro and in vivo.

Results

Our results indicated that USP15 stimulated TGF-β/SMAD2 signaling and the cartilage phenotype. Moreover, ERK2 required USP15 to influence TGF-β/SMAD2 signaling for regulating the cartilage phenotype in vivo and in vitro. And USP15 can form a complex with ERK2 to regulate ubiquitination of ERK2. Interestingly, USP15 did not regulate the stability of ERK2 but increased the level of p-ERK1/2 to further enhance the TGF-β/SMAD2 signaling pathway.

Conclusions

Taken together, our study revealed positive feedback regulation between USP15 and ERK2, which played a critical role in TGF-β/SMAD2 signaling to inhibit OA progression. Therefore, this specific mechanism can guide the clinical treatment of OA.