Interferon-γ-mediated secretion of tryptophanyl-tRNA synthetases has a role in protection of human umbilical cord blood-derived mesenchymal stem cells against experimental colitis

Preconditioning of Mesenchymal Stem Cells Enhances the Neuroprotective Effects of Their Conditioned Medium in an Alzheimer's Disease In Vitro Model

BACKGROUND

Alzheimer's disease (AD) develops as a result of oxidative damage to neurons and chronic inflammation of microglia. These processes can be influenced by the use of a conditioned medium (CM) derived from mesenchymal stem cells (MSCs). The CM contains a wide range of factors that have neurotrophic, antioxidant, and anti-inflammatory effects. In addition, the therapeutic potential of the CM can be further enhanced by pretreating the MSCs to increase their paracrine activity. The current study aimed to investigate the neuroprotective effects of CM derived from MSCs, which were either activated by a TLR3 ligand or exposed to CoCl2, a hypoxia mimetic (pCM or hCM, respectively), in an in vitro model of AD.

METHODS

We have developed a novel in vitro model of AD that allows us to investigate the neuroprotective and anti-inflammatory effects of MSCs on induced neurodegeneration in the PC12 cell line and the activation of microglia using THP-1 cells.

RESULTS

This study demonstrates for the first time that pCM and hCM exhibit more pronounced immunosuppressive effects on proinflammatory M1 macrophages compared to CM derived from untreated MSCs (cCM). This may help prevent the development of neuroinflammation by balancing the M1 and M2 microglial phenotypes via the decreased secretion of proinflammatory cytokines (IL-1β, IL-6, and TNF-α) and increased secretion of IL-4, as well as the expression of IL-10 and TGF-β by macrophages. Moreover, a previously unknown increase in the neurotrophic properties of hCM was discovered, which led to an increase in the viability of neuron-like PC12 cells under H2O2-induced oxidative-stress conditions. These results are likely associated with an increase in the production of growth factors, including vascular endothelial growth factor (VEGF). In addition, the neuroprotective effects of CM from preconditioned MSCs are also mediated by the activation of the Nrf2/ARE pathway in PC12 cells.

CONCLUSIONS

TLR3 activation in MSCs leads to more potent immunosuppressive effects of the CM against pro-inflammatory M1 macrophages, while the use of hCM led to increased neurotrophic effects after H2O2-induced damage to neuronal cells. These results are of interest for the potential treatment of AD with CM from preactivated MSCs.

The effect of TLR3 priming conditions on MSC immunosuppressive properties

BACKGROUND

Mesenchymal stromal cells (MSCs) have regenerative and immunomodulatory properties, making them suitable for cell therapy. Toll-like receptors (TLRs) in MSCs respond to viral load by secreting immunosuppressive or proinflammatory molecules. The expression of anti-inflammatory molecules in MSCs can be altered by the concentration and duration of exposure to the TLR3 ligand polyinosinic-polycytidylic acid (poly(I:C)). This study aimed to optimize the preconditioning of MSCs with poly(I:C) to increase immunosuppressive effects and to identify MSCs with activated TLR3 (prMSCs).

METHODS

Flow cytometry and histochemical staining were used to analyze MSCs for immunophenotype and differentiation potential. MSCs were exposed to poly(I:C) at 1 and 10 μg/mL for 1, 3, and 24 h, followed by determination of the expression of IDO1, WARS1, PD-L1, TSG-6, and PTGES2 and PGE2 secretion. MSCs and prMSCs were cocultured with intact (J-) and activated (J+) Jurkat T cells. The proportion of proliferating and apoptotic J+ and J- cells, IL-10 secretion, and IL-2 production after cocultivation with MSCs and prMSCs were measured. Liquid chromatography-mass spectrometry and bioinformatics analysis identified proteins linked to TLR3 activation in MSCs.

RESULTS

Poly(I:C) at 10 μg/mL during a 3-h incubation caused the highest expression of immunosuppression markers in MSCs. Activation of prMSCs caused a 18% decrease in proliferation and a one-third increase in apoptotic J+ cells compared to intact MSCs. Cocultures of prMSCs and Jurkat cells had increased IL-10 and decreased IL-2 in the conditioned medium. A proteomic study of MSCs and prMSCs identified 53 proteins with altered expression. Filtering the dataset with Gene Ontology and Reactome Pathway revealed that poly(I:C)-induced proteins activate the antiviral response. Protein‒protein interactions by String in prMSCs revealed that the antiviral response and IFN I signaling circuits were more active than in native MSCs. prMSCs expressed more cell adhesion proteins (ICAM-I and Galectin-3), PARP14, PSMB8, USP18, and GBP4, which may explain their anti-inflammatory effects on Jurkat cells.

CONCLUSIONS

TLR3 activation in MSCs is dependent on exposure time and poly(I:C) concentration. The maximum expression of immunosuppressive molecules was observed with 10 µg/mL poly(I:C) for 3-h preconditioning. This priming protocol for MSCs enhances the immunosuppressive effects of prMSCs on T cells.

The pathophyiological role of aminoacyl-tRNA synthetases in digestive system diseases

Aminoacyl-tRNA synthetases (ARSs) catalyze the ligation of amino acids to their cognate transfer RNAs and are indispensable enzymes for protein biosynthesis in all the cells. Previously, ARSs were considered simply as housekeeping enzymes, however, they are now known to be involved in a variety of physiological and pathological processes, such as tumorigenesis, angiogenesis, and immune response. In this review, we summarize the role of ARSs in the digestive system, including the esophagus, stomach, small intestine, colon, as well as the auxiliary organs such as the pancreas, liver, and the gallbladder. Furthermore, we specifically focus on the diagnostic and prognostic value of ARSs in cancers, aiming to provide new insights into the pathophysiological implications of ARSs in tumorigenesis.

Identification of causal metabolites related to multiple autoimmune diseases

OBJECT

Observational studies provide evidence that metabolites may be involved in the development of autoimmune diseases (ADs), but whether it is causal is still unknown.

METHODS

Based on the large-scale GWAS summary statistics, two-sample Mendelian randomization (MR) was performed to evaluate the causal association between human serum metabolites and multiple ADs, which were inflammatory bowel disease (IBD), ulcerative Colitis (UC), crohn's disease (CD), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), multiple sclerosis (MS), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Comprehensive sensitive analysis was used to validate the robustness of MR results and multivariable MR analysis was conducted to avoid potential pleiotropic effect of other complex traits. Finally, metabolic pathway analysis was performed based on causal metabolites for each ad, respectively.

RESULTS

We identified 6 causal features of metabolite after Bonferroni adjustment, i.e. glycerol 2-phosphate for T1D, hexadecanedioate, phenylacetylglutamine and laurylcarnitine for RA, glycine and arachidonate (20:4n6) for CD. Then comprehensively sensitive analysis proved the robustness of the causal associations. We also observed some overlaps of metabolites among different ADs, indicating the similar mechanisms. After controlling for several common traits, multivariable MR analysis ruled out most of potential pleiotropic effects and validated the independence of identified metabolites. Additionally, a total of 6 metabolic pathways have been identified for different ADs.

CONCLUSIONS

This study provided novel insights into investigating causal role of serum metabolites in development of multiple ADs through a comprehensive genetic pathway.

Tryptophanyl-tRNA Synthetase as a Potential Therapeutic Target

Tryptophanyl-tRNA synthetase (WRS) is an essential enzyme that catalyzes the ligation of tryptophan (Trp) to its cognate tRNA^trp during translation via aminoacylation. Interestingly, WRS also plays physiopathological roles in diseases including sepsis, cancer, and autoimmune and brain diseases and has potential as a pharmacological target and therapeutic. However, WRS is still generally regarded simply as an enzyme that produces Trp in polypeptides; therefore, studies of the pharmacological effects, therapeutic targets, and mechanisms of action of WRS are still at an emerging stage. This review summarizes the involvement of WRS in human diseases. We hope that this will encourage further investigation into WRS as a potential target for drug development in various pathological states including infection, tumorigenesis, and autoimmune and brain diseases.

Therapeutic Effect of Mesenchymal Stem Cells in Ulcerative Colitis: A Review on Achievements and Challenges

The worldwide epidemiology of inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), still shows an increasing trend in Asia and Iran. Despite an improvement in the treatment landscape focused on symptomatic control, long-term colectomies have not decreased over the last 10-year period. Thus, novel therapies are urgently needed in clinics to supplement the existing treatments. Mesenchymal stem cells (MSCs) are multipotent adult stem cells with immunosuppressive effects, targeting IBD as a new treatment strategy. They have recently received global attention for their use in cell transplantation due to their easy expansion and wide range of activities to be engrafted, and because they are home to the mucosa of the intestine. Moreover, MSCs are able to differentiate into epithelial and other cells that can directly promote repair in the mucosal damages in UC. It seems that there is a need to deepen our understanding to target MSCs as a promising treatment option for UC patients who are refractory to conventional therapies. Here, we overviewed the therapeutic effects of MSCs in UC and discussed the achievements and challenges in the cell transplantation of UC.

Anti-Inflammatory Effects of Magnetically Targeted Mesenchymal Stem Cells on Laser-Induced Skin Injuries in Rats

Introduction

Mesenchymal stem cells (MSCs) are a promising resource for tissue regeneration and repair. However, their clinical application is hindered by technical limitations related to MSC enrichment at the target sites.

Methods

MSCs were labeled with magnetic Fe₃O₄ nanoparticles (NPs). We analyzed the effects of NP on cell proliferation, stem cell characteristics, and cytokine secretion. Furthermore, we induced NP-labeled MSC migration with an external magnetic field toward laser-induced skin wounds in rats and evaluated the associated anti-inflammatory effects.

Results

Fe₃O₄ NP application did not adversely affect MSC characteristics. Moreover, Fe₃O₄ NP-labeled MSCs presented increased anti-inflammatory cytokine and chemokine production compared with unlabeled MSCs. Furthermore, MSCs accumulated at the injury site and magnetic targeting promoted NP-labeled MSC migration toward burn injury sites in vivo. On day 7 following MSC injection, reduced inflammation and promoted angiogenesis were observed in the magnetically targeted MSC group. In addition, anti-inflammatory factors were upregulated, whereas pro-inflammatory factors were downregulated within the magnetically targeted MSC group compared with those in the PBS group.

Conclusion

This study demonstrates that magnetically targeted MSCs contribute to cell migration to the site of skin injury, improve anti-inflammatory effects and enhance angiogenesis compared with MSC injection alone. Therefore, magnetically targeted MSC therapy may be an effective treatment approach for epithelial tissue injuries.

Inhibition of LSD1 phosphorylation alleviates colitis symptoms induced by dextran sulfate sodiumInhibition of LSD1 phosphorylation alleviates colitis symptoms induced by dextran sulfate sodium

Inflammatory Bowel Disease is caused by an acute or chronic dysfunction of the mucosal inflammatory system in the intestinal tract. In line with the results of our previous study, wherein we found that the PKCα-LSD1-NF-κB signaling plays a critical role in the prolonged activation of the inflammatory response, we aimed to investigate the effect of signaling on colitis in the present study. Lsd1 S112A knock-in (Lsd1^SA/SA) mice, harboring a deficiency in phosphorylation by PKCα, exhibited less severe colitis symptoms and a relatively intact colonic epithelial lining in dextran sulfate sodium (DSS)-induced colitis models. Additionally, a reduction in pro-inflammatory gene expression and immune cell recruitment into damaged colon tissues in Lsd1^SA/SA mice was observed upon DSS administration. Furthermore, LSD1 inhibition alleviated colitis symptoms and reduced colonic inflammatory responses. Both LSD1 phosphorylation and its activity jointly play a role in the progression of DSS-induced colitis. Therefore, the inhibition of LSD1 activity could potentially protect against the colonic inflammatory response.

Potential methods for improving the efficacy of mesenchymal stem cells in the treatment of inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are a group of chronic recurrent gastrointestinal inflammatory diseases, including ulcerative colitis (UC), Crohn's disease (CD) and IBD unclassified. The pathogenesis may be related to the mucosal immune dysfunction in genetically susceptible hosts affected by environmental factors. Current therapeutic agents mainly include aminosalicylates, corticosteroids, immunosuppressive drugs and novel biological agents. The purpose of treatment is to suppress inflammation and prevent irreversible structural damage. However, long-term application of these drugs may lead to multiple adverse effects and is not always effective. Mesenchymal stem cells (MSCs) are multipotent progenitors with low immunogenicity, which can be obtained and expanded easily. They play an important role in regulating immune responses and repairing damaged tissues in vivo. Therefore, MSCs are considered to be a promising option for the treatment of IBD. Nonetheless, there are many factors that can reduce the efficacy of MSCs, such as gradual deterioration of functional stem cells with age, low recruitment and persistence in vivo and different routes of administration. In recent years, researchers have been able to improve the efficacy of MSCs by pretreatment, genetic modification or co-application with other substances, as well as using different tissue-derived cells, administration methods or doses. This article reviews these methods to provide references for more effective application of MSCs in the treatment of IBD in the future.

Tryptophanyl-tRNA Synthetase, a Novel Damage-Induced Cytokine, Significantly Increases the Therapeutic Effects of Endometrial Stem Cells

The major challenges of most adult stem cell-based therapies are their weak therapeutic effects caused by the loss of multilineage differentiation capacity and homing potential. Recently, many researchers have attempted to identify novel stimulating factors that can fundamentally increase the differentiation capacity and homing potential of various types of adult stem cells. Tryptophanyl-tRNA synthetase (WRS) is a highly conserved and ubiquitously expressed enzyme that catalyzes the first step of protein synthesis. In addition to this canonical function, we found for the first time that WRS is actively released from the site of injury in response to various damage signals both in vitro and in vivo and then acts as a potent nonenzymatic cytokine that promotes the self-renewal, migratory, and differentiation capacities of endometrial stem cells to facilitate the repair of damaged tissues. Furthermore, we also found that WRS, through its functional receptor cadherin-6 (CDH-6), activates major prosurvival signaling pathways, such as Akt and extracellular signal-regulated kinase (ERK)1/2 signaling. Our current study provides novel and unique insights into approaches that can significantly enhance the therapeutic effects of human endometrial stem cells in various clinical applications.

Cell membrane and bioactive factors derived from mesenchymal stromal cells: Cell-free based therapy for inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are chronic inflammatory disorders of the gastrointestinal tract associated with multifactorial conditions such as ulcerative colitis and Crohn’s disease. Although the underlying mechanisms of IBD remain unclear, growing evidence has shown that dysregulated immune system reactions in genetically susceptible individuals contribute to mucosal inflammation. However, conventional treatments have been effective in inducing remission of IBD but not in preventing the relapse of them. In this way, mesenchymal stromal cells (MSC) therapy has been recognized as a promising treatment for IBD due to their immunomodulatory properties, ability to differentiate into several tissues, and homing to inflammatory sites. Even so, literature is conflicted regarding the location and persistence of MSC in the body after transplantation. For this reason, recent studies have focused on the paracrine effect of the biofactors secreted by MSC, especially in relation to the immunomodulatory potential of soluble factors (cytokines, chemokines, and growth factors) and extracellular vehicles that are involved in cell communication and in the transfer of cellular material, such as proteins, lipids, and nucleic acids. Moreover, treatment with interferon-γ, tumor necrosis factor-α, and interleukin-1β causes MSC to express immunomodulatory molecules that mediate the suppression via cell-contact dependent mechanisms. Taken together, we present an overview of the role of bioactive factors and cell membrane proteins derived from MSC as a cell-free therapy that can improve IBD treatment.