The intrinsic expression of NLRP3 in Th17 cells promotes their protumor activity and conversion into Tregs

Th17 cells can perform either regulatory or inflammatory functions depending on the cytokine microenvironment. These plastic cells can transdifferentiate into Tregs during inflammation resolution, in allogenic heart transplantation models, or in cancer through mechanisms that remain poorly understood. Here, we demonstrated that NLRP3 expression in Th17 cells is essential for maintaining their immunosuppressive functions through an inflammasome-independent mechanism. In the absence of NLRP3, Th17 cells produce more inflammatory cytokines (IFNγ, Granzyme B, TNFα) and exhibit reduced immunosuppressive activity toward CD8+ cells. Moreover, the capacity of NLRP3-deficient Th17 cells to transdifferentiate into Treg-like cells is lost. Mechanistically, NLRP3 in Th17 cells interacts with the TGF-β receptor, enabling SMAD3 phosphorylation and thereby facilitating the acquisition of immunosuppressive functions. Consequently, the absence of NLRP3 expression in Th17 cells from tumor-bearing mice enhances CD8 + T-cell effectiveness, ultimately inhibiting tumor growth.

Regulatory T Cells Promote Osteogenic Differentiation of Periodontal Ligament Stem Cells through the Jagged1-Notch2 Signaling Axis

OBJECTIVES

This study aimed to elucidate the role of regulatory T cells (Tregs) in promoting the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) and to investigate the underlying mechanisms involving Notch signaling.

METHOD

Tregs were isolated via fluorescence-activated cell sorting (FACS) and co-cultured with PDLSCs. Osteogenic differentiation was assessed through in vitro assays and in vivo transplantation experiments. Gene expression profiles were quantified using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot analysis. A murine periodontitis model was used to validated therapeutic outcomes, with bone remodeling quantified by micro-CT and histology (H&E, Masson's staining). Immunophenotypic analysis of Jagged1 expression in Tregs and Notch2 receptor localization in PDLSCs were performed using flow cytometry and immunofluorescence microscopy, respectively. The role of immobilized Jagged1 in osteogenic differentiation was further evaluated, while Notch pathway inhibition was achieved via γ-secretase inhibitor DAPT in vitro.

RESULTS

Elevated levels of Th17 cells and Tregs were observed in peripheral blood samples from periodontitis patients, with a significantly increased Th17/Treg ratio (p < 0.01). In vitro, co-culturing Tregs with PDLSCs significantly enhanced PDLSC osteogenesis, as evidenced by increased ALP activity (p < 0.01), elevated expression of osteogenesis-related genes (Runx2 and Osterix; p < 0.01), and enhanced mineralization (Alizarin Red staining) (p < 0.01). In vivo, intravenous infusion of Tregs into a periodontitis mouse model reduced periodontal damage and promoted bone regeneration, as demonstrated by reduced CEJ-ABC distance and increased BV/TV ratio (p < 0.01). Mechanistically, Tregs expressed the Notch ligand Jagged1 and upregulated Notch2 receptor expression in PDLSCs, indicating activation of the Notch signaling pathway. Jagged1 promoted osteogenic differentiation of PDLSCs in a dose- and time-dependent manner. Inhibition of Notch signaling using DAPT reduced Tregs-mediated enhancement of PDLSC osteogenesis (p < 0.05).

CONCLUSION

These findings suggest that Tregs promote PDLSC osteogenic differentiation via Jagged1-Notch2 signaling, highlighting the therapeutic potential of modulating Tregs and Notch signaling for periodontal regeneration and bone tissue engineering.

CLINICAL SIGNIFICANCE

This study provides new insights into the complex interplay between immune modulation and stem cell differentiation, laying the foundation for potential Tregs-based therapeutic strategies for periodontal and bone tissue regeneration.

Nucleotide-binding oligomerization domain-like receptor family caspase recruitment domain containing protein 5 affects the progression of periodontitis by regulating the function of periodontal membrane cells

Background/purpose

Nucleotide-binding oligomerization domain-like receptor family caspase recruitment domain containing protein 5 (NLRC5) plays a regulatory role in innate and adaptive immunity. However, its role in periodontitis remains unclear. This study investigated the effects of NLRC5 on periodontitis and the underlying mechanism.

Materials and methods

Experimental periodontitis models of wild-type and Nlrc5 knockout mice were established to detect alveolar bone loss. The inflammatory environment was established with Porphyromonas. gingivalis lipopolysaccharide (P. gingivalis LPS). The expression of NLRC5 in periodontal ligament stem cells (PDLSCs) were detected with P. gingivalis LPS stimulated. After knocking-down or overexpressing the NLRC5 expression level, the inflammatory cytokine level and osteogenic ability of PDLSCs were detected.

Results

The Nlrc5 knockout mice exhibited greater alveolar bone loss in periodontitis. In the presence of P. gingivalis LPS, the expression of NLRC5 decreased. Downregulating NLRC5 increased the expression of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α). Upregulated NLRC5 inhibited nuclear factor kappa-B (NF-κB) signaling and inhibited the expression of those proinflammatory factors. NLRC5 had a positive regulatory effect on the osteogenic differentiation of PDLSCs. When NLRC5 was knocked down, the ALP activity and the number of mineralized nodules in PDLSCs decreased. Conversely, overexpression of NLRC5 enhanced the osteogenic differentiation ability of PDLSCs. Overexpression of NLRC5 increased the osteogenic differentiation of PDLSCs in inflammatory environments.

Conclusion

NLRC5 affects the progression of periodontitis by regulating the function of PDLSCs. NLRC5 reduced the expression of inflammatory factors by inhibiting NF-κB, and had a positive regulatory effect on the osteogenic differentiation of PDLSCs.

Drug delivery strategies for local immunomodulation in transplantation: Bridging the translational gap

Drug delivery strategies for local immunomodulation hold tremendous promise compared to current clinical gold-standard systemic immunosuppression as they could improve the benefit to risk ratio of life-saving or life-enhancing transplants. Such strategies have facilitated prolonged graft survival in animal models at lower drug doses while minimizing off-target effects. Despite the promising outcomes in preclinical animal studies, progression of these strategies to clinical trials has faced challenges. A comprehensive understanding of the translational barriers is a critical first step towards clinical validation of effective immunomodulatory drug delivery protocols proven for safety and tolerability in pre-clinical animal models. This review overviews the current state-of-the-art in local immunomodulatory strategies for transplantation and outlines the key challenges hindering their clinical translation.

Curcumin as a regulator of Th17 cells: Unveiling the mechanisms

Curcumin, a polyphenol natural product derived from turmeric, possesses diverse pharmacological effects due to its interactions with various cells and molecules. Recent studies have highlighted its immunomodulatory properties, including its impact on immune cells and mediators involved in immune responses. Th17 cells play a crucial role in promoting immune responses against extracellular pathogens by recruiting neutrophils and inducing inflammation. These cells produce inflammatory cytokines such as TNF-α, IL-21, IL-17A, IL-23, IL-17F, IL-22, and IL-26. Curcumin has been shown to significantly inhibit the proliferation of Th17 cells and reduce the production of inflammatory cytokines, including TNF-α, IL-22, and IL-17. This review aims to assess the effectiveness of curcumin and its underlying mechanisms in modulating Th17 cells.

Bone marrow mesenchymal stem cells suppress activated CD4+ T cells proliferation through TGF-beta and IL10 dependent of autophagy in pathological hypoxic microenvironment

BACKGROUND

Bone marrow mesenchymal stem cells (BMSCs) mediated immunomodulation by secreting certain bioactive cytokines has been recognized as a promising approach for disease treatment. However, microenvironmental oxygen tension affect immunomodulatory functions and activate autophagy in BMSCs. The mechanism governing BMSCs immunomodulation in hypoxia hasn't been expounded clearly. The aim of this study is to investigate the function of pathological hypoxia on immunomodulatory properties of bone marrow mesenchymal stem cells and its possible mechanism.

METHODS

BMSCs were cultured in either normoxia (21 % oxygen) or hypoxia (0.1 % oxygen) for 24 h, then electron microscopy (EM) and immunofluorescence staining were used to detect the activation of autophagy. Besides autophagy-related markers were monitored by Western blotting. Atg5 siRNA induced autophagic inhibition. Additional, gene expression levels of Real-time fluorescence quantitative PCR and Western blot were used to detect BMSCs related cytokines. Both the proliferation and apoptosis of CD4+ T cell in co-culture were detected by flow cytometry. Exogenous anti-IL-10 antibody and anti-TGF-β1 antibody were used in co-cultured BMSCs-CM and CD4+ T cells, which enabled us to assess how autophagy affected BMSCs-mediated CD4+ T cell proliferation in low oxygen tension.

RESULT

Compared with normal BMSCs, Hypo-BMSCs enhanced the immunosuppressive effect of BMSCs on CD4+ T cell proliferation, while si-atg5 weakened the inhibition of Hypo-BMSCs. Furthermore, exogenous anti-TGF-β1 antibody and the addition of anti-TGF-β1 antibody reversed the immunosuppressive ability of Hypo-BMSCs.

CONCLUSIONS

Our findings reveal that BMSCs possess significant immunosuppression on CD4+T cell through IL-10 and TGF-β1 dependent of autophagy in hypoxic microenvironment.

Mesenchymal stromal cells (MSCs) as a therapeutic agent of inflammatory disease and infectious COVID-19 virus: live or dead mesenchymal?

The COVID-19 infection is a worldwide disease that causes numerous immune-inflammatory disorders, tissue damage, and lung dysfunction. COVID-19 vaccines, including those from Pfizer, AstraZeneca, and Sinopharm, are available globally as effective interventions for combating the disease. The severity of COVID-19 can be most effectively reduced by mesenchymal stromal cells (MSCs) because they possess anti-inflammatory activity and can reverse lung dysfunction. MSCs can be harvested from various sources, such as adipose tissue, bone marrow, peripheral blood, inner organs, and neonatal tissues. The regulation of inflammatory cytokines is crucial in inhibiting inflammatory diseases and promoting the presence of anti-inflammatory cytokines for infectious diseases. MSCs have been employed as therapeutic agents for tissue damage, diabetes, autoimmune diseases, and COVID-19 patients. Our research aimed to determine whether live or dead MSCs are more suitable for the treatment of COVID-19 patients. Our findings concluded that dead MSCs, when directly administered to the patient, offer advantages over viable MSCs due to their extended presence and higher levels of immune regulation, such as T-reg, B-reg, and IL-10, compared to live MSCs. Additionally, dead and apoptotic MSCs are likely to be more readily captured by monocytes and macrophages, prolonging their presence compared to live MSCs.

Multifaceted TGF-β signaling, a master regulator: From bench-to-bedside, intricacies, and complexities

Physiological embryogenesis and adult tissue homeostasis are regulated by transforming growth factor-β (TGF-β), an evolutionarily conserved family of secreted polypeptide factors, acting in an autocrine and paracrine manner. The role of TGF-β in inflammation, fibrosis, and cancer is complex and sometimes even contradictory, exhibiting either inhibitory or promoting effects depending on the stage of the disease. Under pathological conditions, especially fibrosis and cancer, overexpressed TGF-β causes extracellular matrix deposition, epithelial-mesenchymal transition, cancer-associated fibroblast formation, and/or angiogenesis. In this review article, we have tried to dive deep into the mechanism of action of TGF-β in inflammation, fibrosis, and carcinogenesis. As TGF-β and its downstream signaling mechanism are implicated in fibrosis and carcinogenesis blocking this signaling mechanism appears to be a promising avenue. However, targeting TGF-β carries substantial risk as this pathway is implicated in multiple homeostatic processes and is also known to have tumor-suppressor functions. There is a need for careful dosing of TGF-β drugs for therapeutic use and patient selection.

Common clinicopathological and immunological features of sarcomatoid carcinoma across organs: A histomorphology-based cross-organ study

Sarcomatoid carcinoma (SC), which can occur in any organ, is a rare disease. To elucidate common characteristics of SC beyond organs, we evaluated clinicopathological and immunological features of SC defined by the single histological criterion beyond organs compared to randomly matched conventional carcinoma (non-SC) adjusted for the disease stage. Immunological features were assessed by multiplex immunohistochemistry, comparing immune cell density in tumor tissues and tumor programmed death-ligand 1 (PD-L1) expression. A total of 101 patients with SC or non-SC (31 lung, 19 esophagus, 22 pancreas, 15 liver, 4 bile duct, 6 kidney, 2 uterus and 2 ovary) were identified among 7197 patients who underwent surgery at our institute (1997-2020). SC was significantly associated with worse survival (HR: 1.571; 95% CI: 1.084-2.277; P = .017). The frequency of postoperative progression within 6 months was significantly higher for SC patients (54% vs 28%; P = .002). The immune profiling revealed the densities of CD8+ T cells (130 vs 72 cells/mm2 ; P = .004) and tumor-associated macrophages (566 vs 413 cells/mm2 ; P < .0001) and the tumor PD-L1 expression score (40% vs 5%; P < .0001) were significantly higher in SCs than in non-SCs. Among 73 SC patients with postoperative progression, multivariate Cox regression analysis showed that immunotherapy tended to be associated with favorable survival (HR: 0.256; 95% CI: 0.062-1.057; P = .060). Collectively, SCs shared clinicopathological and immunological features across organs. Our study can initiate to standardize the pathological definition of SC and provide a rationale for the investigation and development for this rare disease in a cross-organ manner.

Hematopoietic cell-based and non-hematopoietic cell-based strategies for immune tolerance induction in living-donor renal transplantation: A systematic review

INTRODUCTION

Despite its use to prevent acute rejection, lifelong immunosuppression can adversely impact long-term patient and graft outcomes. In theory, immunosuppression withdrawal is the ultimate goal of kidney transplantation, and is made possible by the induction of immunological tolerance. The purpose of this paper is to review the safety and efficacy of immune tolerance induction strategies in living-donor kidney transplantation, both chimerism-based and non-chimerism-based. The impact of these strategies on transplant outcomes, including acute rejection, allograft function and survival, cost, and immune monitoring, will also be discussed.

MATERIALS AND METHODS

Databases such as PubMed, Scopus, and Web of Science, as well as additional online resources such as EBSCO, were exhaustively searched. Adult living-donor kidney transplant recipients who developed chimerism-based tolerance after concurrent bone marrow or hematopoietic stem cell transplantation or those who received non-chimerism-based, non-hematopoietic cell therapy using mesenchymal stromal cells, dendritic cells, or regulatory T cells were studied between 2000 and 2021. Individual sources of evidence were evaluated critically, and the strength of evidence and risk of bias for each outcome of the transplant tolerance study were assessed.

RESULTS

From 28,173 citations, 245 studies were retrieved after suitable exclusion and duplicate removal. Of these, 22 studies (2 RCTs, 11 cohort studies, 6 case-control studies, and 3 case reports) explicitly related to both interventions (chimerism- and non-chimerism-based immune tolerance) were used in the final review process and were critically appraised. According to the findings, chimerism-based strategies fostered immunotolerance, allowing for the safe withdrawal of immunosuppressive medications. Cell-based therapy, on the other hand, frequently did not induce tolerance except for minimising immunosuppression. As a result, the rejection rates, renal allograft function, and survival rates could not be directly compared between these two groups. While chimerism-based tolerance protocols posed safety concerns due to myelosuppression, including infections and graft-versus-host disease, cell-based strategies lacked these adverse effects and were largely safe. There was a lack of direct comparisons between HLA-identical and HLA-disparate recipients, and the cost implications were not examined in several of the retrieved studies. Most studies reported successful immunosuppressive weaning lasting at least 3 years (ranging up to 11.4 years in some studies), particularly with chimerism-based therapy, while only a few investigators used immune surveillance techniques. The studies reviewed were often limited by selection, classification, ascertainment, performance, and attrition bias.

CONCLUSIONS

This review demonstrates that chimerism-based hematopoietic strategies induce immune tolerance, and a substantial number of patients are successfully weaned off immunosuppression. Despite the risk of complications associated with myelosuppression. Non-chimerism-based, non-hematopoietic cell protocols, on the other hand, have been proven to facilitate immunosuppression minimization but seldom elicit immunological tolerance. However, the results of this review must be interpreted with caution because of the non-randomised study design, potential confounding, and small sample size of the included studies. Further validation and refinement of tolerogenic protocols in accordance with local practice preferences is also warranted, with an emphasis on patient selection, cost ramifications, and immunological surveillance based on reliable tolerance assays.

The Multifunction Role of Tumor-Associated Mesenchymal Stem Cells and Their Interaction with Immune Cells in Breast Cancer

Mesenchymal stem cells (MSCs) are a heterogeneous group of progenitor cells that play a multifunctional role including tissue regeneration, self-renewal properties, and differentiate into cells of mesodermal lineage such as adipocytes, osteoblasts, and chondrocytes. MSCs come into contact with tumor microenvironment (TME) and differentiate into tumor-associated MSCs (TA-MSCs). Various substances such as chemokines, cytokines, growth factors, and others are released by tumor cells to recruit MSCs. TA-MSCs induced epithelial-mesenchymal transition (EMT) program which mediates tumor growth progression, migration, and invasion. Role of MSCs in the tumor progression, stemness, malignancy, and treatment resistance in the breast cancer TME. Immunomodulation by MSCs is mediated by a combination of cell contact-dependent mechanisms and soluble substances. Monocytes/macrophages, dendritic cells, T cells, B cells, and NK cells all show signs of MSCs' immunomodulatory capability. In a complicated interplay initiated by MSCs, anti-inflammatory monocytes/macrophages and regulatory T cells (Tregs) play a key role, as they unveil their full immunomodulatory potential. MSC- secreted cytokines are commonly blamed for the interaction between MSCs, monocytes, and Tregs. Here, we review the current knowledge of cellular and molecular mechanisms involved in MSC-mediated immunomodulation and focus on the role MSCs play in breast cancer progression and its TME.Abbreviation MSC: Mesenchymal Stem Cells; TME: Tumor Microenvironment; TAMS; Tumour-associated Macrophages; ECM: Extracellular matrix; CAFs: Cancer-associated Fibroblasts; CFUs: Colony-forming unit Fibroblasts; Tregs: T regulatory cells; Bregs; Regulatory B cells; IFN-γ: Interferon-gamma; TNF-α: Tumour Necrosis Factor-alpha; IL: Interleukin; TGF-β: transforming growth factorβ; PGE2: Prostaglandin E2; CXCR: Chemokine Receptor; Blimp-1; B lymphocyte-induced maturation protein-1; CCL: Chemokine motif ligand; EMT: Epithelial-mesenchymal transition.

A clinically-relevant STING agonist restrains human TH17 cell inflammatory profile

The STING signaling pathway has gained attention over the last few years due to its ability to incite antimicrobial and antitumoral immunity. Conversely, in mouse models of autoimmunity such as colitis and multiple sclerosis, where TH17 cells are implicated in tissue inflammation, STING activation has been associated with the attenuation of immunogenic responses. In this line, STING was found to limit murine TH17 pro-inflammatory program in vitro. Here we demonstrate that 2'3'-c-di-AM(PS)2(Rp,Rp), a STING agonist that has been undergoing clinical trials for antitumor immunotherapy, activates the STING signalosome in differentiating human TH17 cells. Of particular interest, 2'3'-c-di-AM(PS)2(Rp,Rp) reduces IL-17A production and IL23R expression by human TH17 cells while it favors the generation of regulatory T (Treg) cells. These findings suggest that STING agonists may be promising approaches for treating human TH17-mediated chronic inflammation.

Decoding Sepsis-Induced Disseminated Intravascular Coagulation: A Comprehensive Review of Existing and Emerging Therapies

Disseminated intravascular coagulation (DIC) is a recurrent complication of sepsis. Since DIC not only promotes organ dysfunction but also represents a strong prognostic factor, it is important to diagnose DIC as early as possible. When coagulation is activated, fibrinolysis is inhibited, blood thinners are consumed, and a condition is created that promotes blood clotting, making it more difficult for the body to remove fibrin or prevent it from being deposited in the blood vessels. This leads to microvascular thrombosis, which plays a role in organ dysfunction. Despite efforts to understand the underlying mechanisms of sepsis-induced DIC, healthcare providers worldwide still face challenges in effectively treating this condition. In this review, we provide an in-depth analysis of the available strategies for sepsis-induced DIC, considering their effectiveness, limitations, and potential for future advances. Corticosteroids (CS), recombinant thrombomodulin (rTM), vitamin C, fibrinolytic therapy, and platelet transfusion are among the treatments discussed in the review. In addition, we are specifically addressing immunomodulatory therapy (IMT) by investigating treatments such as granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon gamma (IFN-γ), and mesenchymal stem cell therapy (MSC). Finally, we also examined how these therapies might affect COVID-19 cases, which often present with sepsis-induced DIC. The review suggests that targeted experiments with randomization are needed to verify the effectiveness of these treatments and to discover novel approaches to treat sepsis-induced DIC. By increasing our knowledge of sepsis-induced DIC, we can develop targeted treatments that have the potential to save lives and improve outcomes.

The role of Th17 cells in chronic lymphocytic leukemia: friend or foe?

T helper 17 (Th17) cells have a prominent role in autoimmune diseases. In contrast, the nature of these cells in cancer is controversial, with either pro- or antitumorigenic activities depending on various cancer settings. Chronic lymphocytic leukemia (CLL), a B-cell malignancy, is characterized by an imbalance in T-cell immune responses that contributes to disease progression and increased mortality. Many clinical reports indicate an increase in Th17 cells and/or interleukin 17 serum cytokine levels in patients with CLL compared with healthy individuals, which correlates with various prognostic markers and significant changes in the tumor microenvironment. The exact mechanisms by which Th17 cells might contribute to CLL progression remain poorly investigated. In this review, we provide an updated presentation of the clinical information related to the significance of Th17 cells in CLL and their interaction with the complex leukemic microenvironment, including various mediators, immune cells, and nonimmune cells. We also address the available data regarding the effects of CLL-targeted therapies on Th17 cells and the potential of using these cells in adoptive cell therapies. Having a sound understanding of the role played by Th17 cells in CLL is crucial for designing novel therapies that can achieve immune homeostasis and maximize clinical benefits.

Evaluation of the relationship between mesenchymal stem cells and immune system in vitro conditions

BACKGROUND

Mesenchymal stem cells (MSCs), are a novel therapeutic option as the most common cell source, play an important role in the immunomodulation. In this study, it was aimed to determine the effect of MSCs on cytokines secreted by the immune system cells.

METHODS

Intracellular cytokine levels (Interleukin-4 (IL-4), Interferon-γ (IFN-γ), and Interleukin-17 (IL-17)) detected by flow cytometry before and after co-culture between peripheral blood mononuclear cells (PBMCs) and MCSs. At the same time, supernatant cytokine levels were measured using the ELISA.

RESULTS

In our study, MSCs were isolated from cord blood (CB) and Wharton's Jelly (WJ), and their surface markers (CD44 (100%), CD73 (99.6%), CD90 (100%), CD105 (88%)) shown by flow cytometry method. Both CB-MSCs and WJ-MSCs were used in co-culture MSC/PBMC ratios of 1/5 and 1/10, incubation times of 24 h and 72 h. In the present study, when we compared co-cultures of CB-MSC or WJ-MSC with PBMCs, intracellular levels of cytokines IFN-γ, IL-17 (pro-inflamatory) and IL-4 (anti-inflamatory) were increased, and supernatant levels were decreased significantly (p < 0.05). The level of transforming growth factor beta (TGF-β) (anti-inflamatory) was significantly decreased for both CB-MSC and WJ-MSC in supernatant (p < 0.05).

CONCLUSIONS

It was investigated pro-inflammatory and anti-inflammatory effects of CB-MSCs and WJ-MSCs on PBMCs with the obtained results. According to the results, MSCs demonstrated different immunologic effects after the incubation time and ratios. For further studies, it should be known between interaction of MSCs and immune system.

Transcriptional and Epigenetic Regulation of Context-Dependent Plasticity in T-Helper Lineages

Th cell lineage determination and functional specialization are tightly linked to the activation of lineage-determining transcription factors (TFs) that bind cis-regulatory elements. These lineage-determining TFs act in concert with multiple layers of transcriptional regulators to alter the epigenetic landscape, including DNA methylation, histone modification and three-dimensional chromosome architecture, in order to facilitate the specific Th gene expression programs that allow for phenotypic diversification. Accumulating evidence indicates that Th cell differentiation is not as rigid as classically held; rather, extensive phenotypic plasticity is an inherent feature of T cell lineages. Recent studies have begun to uncover the epigenetic programs that mechanistically govern T cell subset specification and immunological memory. Advances in next generation sequencing technologies have allowed global transcriptomic and epigenomic interrogation of CD4+ Th cells that extends previous findings focusing on individual loci. In this review, we provide an overview of recent genome-wide insights into the transcriptional and epigenetic regulation of CD4+ T cell-mediated adaptive immunity and discuss the implications for disease as well as immunotherapies.

Toward transplantation tolerance with adipose tissue-derived therapeutics

Solid organ and composite tissue allotransplanation have been widely applied to treat end-stage organ failure and massive tissue defects, respectively. Currently there are a lot of research endeavors focusing on induction of transplantation tolerance, to relieve the burden derived from long-term immunosuppressant uptake. The mesenchymal stromal cells (MSCs) have been demonstrated with potent immunomodulatory capacities and applied as promising cellular therapeutics to promote allograft survival and induce tolerance. As a rich source of adult MSCs, adipose tissue provides additional advantages of easy accessibility and good safety profile. In recent years, the stromal vascular fraction (SVF) isolated from adipose tissues following enzymatic or mechanical processing without in vitro culture and expansion has demonstrated immunomodulatory and proangiogenic properties. Furthermore, the secretome of AD-MSCs has been utilized in transplantation field as a potential "cell-free" therapeutics. This article reviews recent studies that employ these adipose-derived therapeutics, including AD-MSCs, SVF, and secretome, in various aspects of organ and tissue allotransplantation. Most reports validate their efficacies in prolonging allograft survival. Specifically, the SVF and secretome have performed well for graft preservation and pretreatment, potentially through their proangiogenic and antioxidative capacities. In contrast, AD-MSCs were suitable for peri-transplantation immunosuppression. The proper combination of AD-MSCs, lymphodepletion and conventional immunosuppressants could consistently induce donor-specific tolerance to vascularized composite allotransplants (VCA). For each type of transplantation, optimizing the choice of therapeutics, timing, dose, and frequency of administration may be required. Future progress in the application of adipose-derived therapeutics to induce transplantation tolerance will be further benefited by continued research into their mechanisms of action and the development of standardized protocols for isolation methodologies, cell culture, and efficacy evaluation.

Timing of Mesenchymal Stromal Cell Therapy Defines its Immunosuppressive Effects in a Rat Lung Transplantation Model

Cell therapy using mesenchymal stromal cells (MSCs) is being studied for its immunosuppressive effects. In organ transplantation, the amount of MSCs that accumulate in transplanted organs and other organs may differ depending on administration timing, which may impact their immunosuppressive effects. In vitro, adipose-derived mesenchymal stem cells (ADMSCs) suppress lymphocyte activation under cell-to-cell contact conditions. However, in vivo, it is controversial whether ADMSCs are more effective in accumulating in transplanted organs or in secondary lymphoid organs. Herein, we aimed to investigate whether the timing of ADMSC administration affects its immunosuppression ability in a rat lung transplantation model. In the transplantation study, rats were intramuscularly administered half the usual dose of tacrolimus (0.5 mg/kg) every 24 h after lung transplantation. ADMSCs (1 × 106) were administered via the jugular vein before (PreTx) or after (PostTx) transplantation. Cell tracking using quantum dots was performed. ADMSCs accumulated predominantly in the lung and liver; fewer ADMSCs were distributed in the grafted lung in the PreTx group than in the PostTx group. The rejection rate was remarkably low in the ADMSC-administered groups, particularly in the PostTx group. Serum tumor necrosis factor-α (TNF-α), interferon-γ, and interleukin (IL)-6 levels showed a greater tendency to decrease in the PreTx group than in the PostTx group. The proportion of regulatory T cells in the grafted lung 10 days after transplantation was higher in the PostTx group than in the PreTx group. PostTx administration suppresses rejection better than PreTx administration, possibly due to regulatory T cell induction by ADMSCs accumulated in the transplanted lungs, suggesting a mechanism different from that in heart or kidney transplantation that PreTx administration is more effective than PostTx administration. These results could help establish cell therapy using MSCs in lung transplantation.

Use of Mesenchymal Stem Cells in Crohn's Disease and Perianal Fistulas: A Narrative Review

Crohn's Disease (CD), which usually leads to anal fistulas among patients, is the most important inflammatory bowel disease that causes morbidity in many people around the world. This review article proposes using MSCs as a hopeful therapeutic strategy for CD and anal fistula treatment in both preclinical and clinical conditions. Finally, darvadstrocel, a cell-based medication to treat complex anal fistulas in adults, as the only European Medicines Agency (EMA)-approved product for the treatment of anal fistulas in CD is addressed. Although several common therapies, such as surgery and anti-tumor necrosis factor-alpha (TNF-α) drugs as well as a combination of these methods is used to improve this disease, however, due to the low effectiveness of these treatments, the use of new strategies with higher efficiency is still recommended. Cell therapy is among the new emerging therapeutic strategies that have attracted great attention from clinicians due to its unique capabilities. One of the most widely used cell sources administrated in cell therapy is mesenchymal stem cell (MSC). This review article will discuss preclinical and clinical studies about MSCs as a potent and promising therapeutic option in the treatment of CD and anal fistula.

The immunological role of mesenchymal stromal cells in patients with myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a common hematological malignant disease, characterized by malignant hematopoietic stem cell proliferation in the bone marrow (BM); clinically, it mainly manifests clinically mainly by as pathological hematopoiesis, hemocytopenia, and high-risk transformation to acute leukemia. Several studies have shown that the BM microenvironment plays a critical role in the progression of MDS. In this study, we specifically evaluated mesenchymal stromal cells (MSCs) that exert immunomodulatory effects in the BM microenvironment. This immunomodulatory effect occurs through direct cell-cell contact and the secretion of soluble cytokines or micro vesicles. Several researchers have compared MSCs derived from healthy donors to low-risk MDS-associated bone mesenchymal stem cells (BM-MSCs) and have found no significant abnormalities in the MDS-MSC phenotype; however, these cells have been observed to exhibit altered function, including a decline in osteoblastic function. This altered function may promote MDS progression. In patients with MDS, especially high-risk patients, MSCs in the BM microenvironment regulate immune cell function, such as that of T cells, B cells, natural killer cells, dendritic cells, neutrophils, myeloid-derived suppressor cells (MDSCs), macrophages, and Treg cells, thereby enabling MDS-associated malignant cells to evade immune cell surveillance. Alterations in MDS-MSC function include genomic instability, microRNA production, histone modification, DNA methylation, and abnormal signal transduction and cytokine secretion.

Bioscaffold developed with decellularized human amniotic membrane seeded with mesenchymal stromal cells: assessment of efficacy and safety profiles in a second-degree burn preclinical model

Therapies to deep burn injuries remain a global challenge. Human amniotic membrane (hAM) is a biomaterial that has been increasingly explored by the field of regenerative medicine. A decellularized hAM (DhAM) can be used as scaffold for mesenchymal stromal cells (MSCs) to grow without the loss of their stemness potential, allowing its application as cell therapy for wound healing. In this work, we associated DhAM with adipose-derived MSCs (DhAM + AD-MSCs), as a therapy strategy for second-degree burns in a preclinical model. Animals with induced second-degree burns were divided into four groups: control, which consists of a non-adherent gauze; a synthetic commercial dressing as the positive control (Control+); DhAM; and DhAM plus rat AD-MSCs (DhAM + AD-MSCs), followed by detailed and long term analysis (5 weeks). The macroscopical analysis showed the healing improvement in the wound area after the DhAM + AD-MSC treatment. Histological analysis also showed no alteration in the animal organs and a regular epithelial progression in comparison to the control. This observation was also confirmed by the analysis of suprabasal layers in the neoepidermis with CK10, showing a stratified and differentiated epithelium, when compared to Control and Control+. A strong CD73 (ecto-5'-nucleotidase) labeling was observed in the first 2 weeks postburn in dermis and epidermis. The expression in dermis was stronger in the second week in the middle of the wound, when comparing the Control+ with DhAM + AD-MSCs (p= 0.0238). In the epidermis the expression of CD73 was increased in all regions when compared to the control. This data suggests the involvement of this protein on wound healing. A low CD11b labeling was observed in DhAM + AD-MSCs treatment group mainly in the last treatment week, in comparison to Control and Control+ (p< 0.0001), which indicates a reduction in the inflammatory process. MSCs through CD73 can release high concentrations of adenosine, an immunosuppressive molecule, suggesting that this could be the mechanism by which the inflammation was better modulated in the DhAM + AD-MSCs group. The results obtained with this preclinical model confirm the effectiveness and safety of this low-cost and highly available dressing for future clinical application as a therapy for burn treatments.

Immunomodulating Hydrogels as Stealth Platform for Drug Delivery Applications

Non-targeted persistent immune activation or suppression by different drug delivery platforms can cause adverse and chronic physiological effects including cancer and arthritis. Therefore, non-toxic materials that do not trigger an immunogenic response during delivery are crucial for safe and effective in vivo treatment. Hydrogels are excellent candidates that can be engineered to control immune responses by modulating biomolecule release/adsorption, improving regeneration of lymphoid tissues, and enhancing function during antigen presentation. This review discusses the aspects of hydrogel-based systems used as drug delivery platforms for various diseases. A detailed investigation on different immunomodulation strategies for various delivery options and deliberate upon the outlook of such drug delivery platforms are conducted.

Perinatal derivatives: How to best validate their immunomodulatory functions

Perinatal tissues, mainly the placenta and umbilical cord, contain a variety of different somatic stem and progenitor cell types, including those of the hematopoietic system, multipotent mesenchymal stromal cells (MSCs), epithelial cells and amnion epithelial cells. Several of these perinatal derivatives (PnDs), as well as their secreted products, have been reported to exert immunomodulatory therapeutic and regenerative functions in a variety of pre-clinical disease models. Following experience with MSCs and their extracellular vesicle (EV) products, successful clinical translation of PnDs will require robust functional assays that are predictive for the relevant therapeutic potency. Using the examples of T cell and monocyte/macrophage assays, we here discuss several assay relevant parameters for assessing the immunomodulatory activities of PnDs. Furthermore, we highlight the need to correlate the in vitro assay results with preclinical or clinical outcomes in order to ensure valid predictions about the in vivo potency of therapeutic PnD cells/products in individual disease settings.

Aloperine Ameliorates IMQ-Induced Psoriasis by Attenuating Th17 Differentiation and Facilitating Their Conversion to Treg

Aloperine is an anti-inflammatory compound isolated from the Chinese herb Sophora alopecuroides L. Previously, our group has reported that the generation of induced Treg was promoted by aloperine treatment in a mouse colitis model. However, the effect of aloperine on effector T cell subsets remains unclear. We therefore carefully examined the effect of aloperine on the differentiation of major subsets of T helper cells. Based on our results, psoriasis, a Th17 dominant skin disease, is selected to explore the potential therapeutic effect of aloperine in vivo. Herein, we demonstrated that topical application of aloperine suppressed epidermal proliferation, erythema, and infiltration of inflammatory cells in skin lesions. Mechanistic studies revealed that aloperine suppressed the differentiation of Th17 cells directly through inhibiting the phosphorylation of STAT3 or indirectly through impairing the secretion of Th17-promoting cytokines by dendritic cells. Moreover, aloperine enhanced the conversion of Th17 into Treg via altering the pSTAT3/pSTAT5 ratio. Collectively, our study supported that aloperine possesses the capacity to affect Th17 differentiation and modulates Th17/Treg balance, thereby alleviating imiquimod (IMQ)-induced psoriasis in mice.

Emerging local immunomodulatory strategies to circumvent systemic immunosuppression in cell transplantation

INTRODUCTION

Cell transplantation is a promising curative therapeutic strategy whereby impaired organ functions can be restored without the need for whole organ transplantation. A key challenge in allotransplantation is the requirement for life-long systemic immunosuppression to prevent rejection, which is associated with serious adverse effects such as increased risk of opportunistic infections and the development of neoplasms. This challenge underscores the urgent need for novel strategies to prevent graft rejection while abrogating toxicity-associated adverse events.

AREAS COVERED

We review recent advances in immunoengineering strategies for localized immunomodulation that aim to support allograft function and provide immune tolerance in a safe and effective manner.

EXPERT OPINION

Immunoengineering strategies are tailored approaches for achieving immunomodulation of the transplant microenvironment. Biomaterials can be adapted for localized and controlled release of immunomodulatory agents, decreasing the effective dose threshold and frequency of administration. The future of transplant rejection management lies in the shift from systemic to local immunomodulation with suppression of effector and activation of regulatory T cells, to promote immune tolerance.

2', 4'-Dihydroxy-2,3-dimethoxychalcone: A pharmacological inverse agonist of RORγt ameliorating Th17-driven inflammatory diseases by regulating Th17/Treg

Multiple sclerosis, inflammatory bowel disease and organ transplant rejection are related to Th17 cell development and inflammatory respond. RORγt, a specific transcription factor regulating Th17 cell differentiation, is a pivotal target for the treatment of diseases. However, the clinical application of RORγt inverse agonists reported so far has been hindered due to limited efficacy and toxic side effects. Plant-derived natural products with drug-like properties and safety are wide and valuable resources for candidate drug discovery. Herein, structure-based virtual screening was used to find out 2',4'-Dihydroxy-2,3-dimethoxychalcone (DDC), a chalcone derivative rich in plants and food, located in the binding pocket of RORγt and targeted to inhibit RORγt activity. DDC repressed murine Th17 differentiation and promoted Treg differentiation remarkably in a dose-dependent manner. In addition, DDC treatment improved experimental autoimmune encephalomyelitis recovery, ameliorated experimental colitis severity, and prevented graft rejection significantly. Mechanically, DDC indirectly stabilized Foxp3 expression by inhibiting RORγt activity and the expression of its target gene profile in vitro and in vivo, which realized its regulation of Th17/Treg balance. In conclusion, our study provides a scientific basis that DDC, as an inverse agonist of RORγt with simple structure, rich sources, low cost, high efficiency, and low toxicity, has great potential for the development of a novel effective immunomodulator for the treatment of Th17-mediated inflammatory diseases.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles for Neonatal Lung Disease: Tiny Particles, Major Promise, Rigorous Requirements for Clinical Translation

Extreme preterm birth disrupts late lung development and puts newborns at risk of developing chronic lung disease, known as bronchopulmonary dysplasia (BPD). BPD can be associated with life-long complications, and currently no effective treatment is available. Cell therapies are entering the clinics to curb complications of extreme preterm birth with several clinical trials testing the feasibility, safety and efficacy of mesenchymal stromal cells (MSCs). The therapeutic effect of MSCs is contained in their secretome, and nanosized membranous structures released by the MSCs, known as extracellular vesicles (EVs), have been shown to be the therapeutic vectors. Driven by this discovery, the efficacy of EV-based therapy is currently being explored in models of BPD. EVs derived from MSCs, contain a rich cargo of anti-inflammatory and pro-angiogenic molecules, making them suitable candidates to treat multifactorial diseases such as BPD. Here, we review the state-of-the-art of preclinical studies involving MSC-derived EVs in models of BPD and highlight technical and regulatory challenges that need to be addressed before clinical translation. In addition, we aim at increasing awareness regarding the importance of rigorous reporting of experimental details of EV experiments and to increase the outreach of the current established guidelines amongst researchers in the BPD field.

Intraperitoneally Delivered Mesenchymal Stem Cells Alleviate Experimental Colitis Through THBS1-Mediated Induction of IL-10-Competent Regulatory B Cells

Mesenchymal stem cells (MSCs) show promising therapeutic potential in treating inflammatory bowel disease (IBD), and intraperitoneal delivery of MSCs have become a more effective route for IBD treatment. However, the underlying mechanisms are still poorly understood. Here, we found that intraperitoneally delivered MSCs significantly alleviated experimental colitis. Depletion of peritoneal B cells, but not macrophages, clearly impaired the therapeutic effects of MSCs. Intraperitoneally delivered MSCs improved IBD likely by boosting the IL-10-producing B cells in the peritoneal cavity, and a single intraperitoneal injection of MSCs could significantly prevent disease severity in a recurrent mouse colitis model, with lower proinflammation cytokines and high level of IL-10. The gene expression profile revealed that thrombospondin-1 (THBS1) was dramatically upregulated in MSCs after coculture with peritoneal lavage fluid from colitis mice. Knockout of THBS1 expression in MSCs abolished their therapeutic effects in colitis and the induction of IL-10-producing B cells. Mechanistically, THBS1 modulates the activation of transforming growth factor-β (TGF-β), which combines with TGF-β receptors on B cells and contributes to IL-10 production. Blocking the interaction between THBS1 and latent TGF-β or inhibiting TGF-β receptors (TGF-βR) significantly reversed the THBS1-mediated induction of IL-10-producing B cells and the therapeutic effects on colitis. Collectively, our study revealed that intraperitoneally delivered MSCs secreted THBS1 to boost IL-10⁺Bregs and control the progression and recurrence of colitis, providing new insight for the prevention and treatment of IBD.

Immunomodulatory effects of mesenchymal stem cells in peripheral nerve injury

Various immune cells and cytokines are present in the aftermath of peripheral nerve injuries (PNI), and coordination of the local inflammatory response is of great significance for the recovery of PNI. Mesenchymal stem cells (MSCs) exhibit immunosuppressive and anti-inflammatory abilities which can accelerate tissue regeneration and attenuate inflammation, but the role of MSCs in the regulation of the local inflammatory microenvironment after PNI has not been widely studied. Here, we summarize the known interactions between MSCs, immune cells, and inflammatory cytokines following PNI with a focus on the immunosuppressive role of MSCs. We also discuss the immunomodulatory potential of MSC-derived extracellular vesicles as a new cell-free treatment for PNI.

Umbilical cord mesenchymal stem cells promote neurological repair after traumatic brain injury through regulating Treg/Th17 balance

Traumatic brain injury (TBI) is a brain injury resulting from blunt mechanical external forces, which is a crucial public health and socioeconomic problem worldwide. TBI is one of the leading causes of death or disability. The primary injury of TBI is generally irreversible. Secondary injury caused by neuroinflammation could result in exacerbation of patients, which indicated that anti-inflammation and immunomodulatory were necessary for the treatment of TBI. Accumulated evidence reveals that the transplantation of umbilical cord mesenchymal stem cells (UCMSCs) could regulate the microenvironment in vivo and keep a balance of helper T 17(Th17)/ regulatory T cell (Treg). Therefore, it is reasonable to hypothesize that the UCMSCs could repair neurological impairment by maintaining the balance of Th17/Treg after TBI. In the study, we observed the phenomenon of trans-differentiation of T lymphocytes into Th17 cells after TBI. Rats were divided into Sham, TBI, and TBI + UCMSCs groups to explore the effects of the UCMSCs. The results manifested that trans-differentiation of Th17 into Treg was facilitated by UCMSCs, which was followed by promotion of neurological recovery and improvement of learning and memory in TBI rats. Furthermore, UCMSCs decreased the phosphorylation of nuclear factor-kappa B (NF-κB) and increased the expression of mothers against decapentaplegic homolog 3 (Smad3) in vivo and vitro experiments. In conclusion, UCMSCs maintained Th17/Treg balance via the transforming growth factor-β (TGF-β)/ Smad3/ NF-κB signaling pathway.

In Vitro Cellular and Molecular Interplay between Human Foreskin-Derived Mesenchymal Stromal/Stem Cells and the Th17 Cell Pathway

Foreskin, considered a biological waste material, has been shown to be a reservoir of therapeutic cells. The immunomodulatory properties of mesenchymal stromal/stem cells (MSCs) from the foreskin (FSK-MSCs) are being evaluated in cell-based therapy for degenerative, inflammatory and autoimmune disorders. Within the injured/inflamed tissue, proinflammatory lymphocytes such as IL-17-producing T helper cells (Th17) may interact with the stromal microenvironment, including MSCs. In this context, MSCs may encounter different levels of T cells as well as specific inflammatory signals. Uncovering the cellular and molecular changes during this interplay is central for developing an efficient and safe immunotherapeutic tool. To this end, an in vitro human model of cocultures of FSK-MSCs and T cells was established. These cocultures were performed at different cell ratios in the presence of an inflammatory setting. After confirming that FSK-MSCs respond to ISCT criteria by showing a typical phenotype and multilineage potential, we evaluated by flow cytometry the expression of Th17 cell markers IL-17A, IL23 receptor and RORγt within the lymphocyte population. We also measured 15 human Th17 pathway-related cytokines. Regardless of the T cell/MSC ratio, we observed a significant increase in IL-17A expression associated with an increase in IL-23 receptor expression. Furthermore, we observed substantial modulation of IL-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, INF-γ, sCD40, and TNF-α secretion. These findings suggest that FSK-MSCs are receptive to their environment and modulate the T cell response accordingly. The changes within the secretome of the stromal and immune environment are likely relevant for the therapeutic effect of MSCs. FSK-MSCs represent a valuable cellular product for immunotherapeutic purposes that needs to be further clarified and developed.

Mesenchymal stem cells: ideal seeds for treating diseases

Mesenchymal stem cells (MSCs), a kind of multipotent stem cells with self-renewal ability and multi-differentiation ability, have become the “practical stem cells” for the treatment of diseases. MSCs have immunomodulatory properties and can be used to treat autoimmune diseases, such as systemic lupus erythematosus (SLE) and Crohn’s disease. MSCs also can be used in cancer and aging. At present, many clinical experiments are using MSCs. MSCs can reduce the occurrence of inflammation and apoptosis of tissue cells, and promote the proliferation of endogenous tissue and organ cells, so as to achieve the effect of repairing tissue and organs. MSCs presumably also play an important role in Corona Virus Disease 2019 (COVID-19) infection.

Epigenetic Reprogramming of CD4+ Helper T Cells as a Strategy to Improve Anticancer Immunotherapy

Evidences highlight the role of various CD4⁺ helper T cells (CD4⁺ Th) subpopulations in orchestrating the immune responses against cancers. Epigenetics takes an important part in the regulation of CD4⁺ Th polarization and plasticity. In this review, we described the epigenetic factors that govern CD4⁺ T cells differentiation and recruitment in the tumor microenvironment and their subsequent involvement in the antitumor immunity. Finally, we discussed how to manipulate tumor reactive CD4⁺ Th responses by epigenetic drugs to improve anticancer immunotherapy.

Therapeutic potential of periodontal ligament stem cells

Inflammatory periodontal disease known as periodontitis is one of the most common conditions that affect human teeth and often leads to tooth loss. Due to the complexity of the periodontium, which is composed of several tissues, its regeneration and subsequent return to a homeostatic state is challenging with the therapies currently available. Cellular therapy is increasingly becoming an alternative in regenerative medicine/dentistry, especially therapies using mesenchymal stem cells, as they can be isolated from a myriad of tissues. Periodontal ligament stem cells (PDLSCs) are probably the most adequate to be used as a cell source with the aim of regenerating the periodontium. Biological insights have also highlighted PDLSCs as promising immunomodulator agents. In this review, we explore the state of knowledge regarding the properties of PDLSCs, as well as their therapeutic potential, describing current and future clinical applications based on tissue engineering techniques.

A critical role for Th17 cell-derived TGF-β1 in regulating the stability and pathogenicity of autoimmune Th17 cells

Pathogenic conversion of Th17 cells into multifunctional helper T cells or Th1 cells contributes to the pathogenesis of autoimmune diseases; however, the mechanism regulating the plasticity of Th17 cells remains unclear. Here, we found that Th17 cells expressed latent TGF-β1 in a manner dependent on autocrine TGF-β1. By employing IL-17-producing cell-specific Tgfb1 conditional knockout and fate-mapping systems, we demonstrated that TGF-β1-deficient Th17 cells are relatively susceptible to becoming IFN-γ producers through IL-12Rβ2 and IL-27Rα upregulation. TGF-β1-deficient Th17 cells exacerbated tissue inflammation compared to TGF-β1-sufficient Th17 cells in adoptive transfer models of experimental autoimmune encephalomyelitis and colitis. Thus, TGF-β1 production by Th17 cells provides an essential autocrine signal for maintaining the stability and regulating the pathogenicity of Th17 cells in vivo.

Monocyte-Independent and -Dependent Regulation of Regulatory T-Cell Development in Mycoplasma Infection

BACKGROUND

Although Mycoplasma pneumoniae (MP) infection has been implicated in the pathogenesis of allergic diseases, the mechanism of this trigger remains unknown. We explored the mechanism for how MP infection could tilt the balance between regulatory T cells (Tregs) and Th17 cells.

METHODS

We analyzed the frequency, phenotype, and function of Tregs in patients at the different stages of MP and various virus infections over a period of more than 1 year. We examined the effect of monocytes to elucidate signals that can regulate the balance between Treg and Th17 cells.

RESULTS

The functional activity of Tregs was profoundly impaired during the acute stage of MP as well as viral infections. Upon resolution, however, the Treg function remained impaired even 1 year after MP infection. In the resolution stage, the impaired Treg function was associated with an increase in interleukin (IL) 17A+ Tregs and Th17 cells. Development of Th17 cells was dependent on the "aberrant" proinflammatory monocytes (pMOs), characterized by potent ability to produce IL-6 in a Toll-like receptor 2-dependent manner.

CONCLUSIONS

Depending on the prevalence of the pMOs, Tregs and Th17 cells could mutually regulate the number and function of the other. The pMOs/IL-6 could be crucial therapeutic targets against MP-induced allergic diseases.

Cell therapy in transplantation: A comprehensive review of the current applications of cell therapy in transplant patients with the focus on Tregs, CAR Tregs, and Mesenchymal stem cells

Organ transplantation is a practical treatment for patients with end-stage organ failure. Despite the advances in short-term graft survival, long-term graft survival remains the main challenge considering the increased mortality and morbidity associated with chronic rejection and the toxicity of immunosuppressive drugs. Since a novel therapeutic strategy to induce allograft tolerance seems urgent, focusing on developing novel and safe approaches to prolong graft survival is one of the main goals of transplant investigators. Researchers in the field of organ transplantation are interested in suppressing or optimizing the immune responses by focusing on immune cells including mesenchymal stem cells (MSCs), polyclonal regulatory Tcells (Tregs), and antigen-specific Tregs engineered with chimeric antigen receptors (CAR Tregs). We review the mechanistic pathways, phenotypic and functional characteristics of these cells, and their promising application in organ transplantation.

Mesenchymal stromal cells for the treatment of ocular autoimmune diseases

Mesenchymal stromal cells, commonly referred to as MSCs, have emerged as a promising cell-based therapy for a range of autoimmune diseases thanks to several therapeutic advantages. Key among these are: 1) the ability to modulate innate and adaptive immune responses and to promote tissue regeneration, 2) the ease of their isolation from readily accessible tissues and expansion at scale in culture, 3) their low immunogenicity enabling use as an allogeneic "off-the-shelf" product, and 4) MSC therapy's safety and feasibility in humans, as demonstrated in more than one thousand clinical trials. Evidence from preclinical studies and early clinical trials indicate the therapeutic potential of MSCs and their derivatives for efficacy in ocular autoimmune diseases such as autoimmune uveoretinitis and Sjögren's syndrome-related dry eye disease. In this review, we provide an overview of the current understanding of the therapeutic mechanisms of MSCs, and summarize the results from preclinical and clinical studies that have used MSCs or their derivatives for the treatment of ocular autoimmune diseases. We also discuss the challenges to the successful clinical application of MSC therapy, and suggest strategies for overcoming them.

A Large-Scale Bank of Organ Donor Bone Marrow and Matched Mesenchymal Stem Cells for Promoting Immunomodulation and Transplant Tolerance

Induction of immune tolerance for solid organ and vascular composite allografts is the Holy Grail for transplantation medicine. This would obviate the need for life-long immunosuppression which is associated with serious adverse outcomes, such as infections, cancers, and renal failure. Currently the most promising means of tolerance induction is through establishing a mixed chimeric state by transplantation of donor hematopoietic stem cells; however, with the exception of living donor renal transplantation, the mixed chimerism approach has not achieved durable immune tolerance on a large scale in preclinical or clinical trials with other solid organs or vascular composite allotransplants (VCA). Ossium Health has established a bank of cryopreserved bone marrow (BM), termed "hematopoietic progenitor cell (HPC), Marrow," recovered from deceased organ donor vertebral bodies. This new source for hematopoietic cell transplant will be a valuable resource for treating hematological malignancies as well as for inducing transplant tolerance. In addition, we have discovered and developed a large source of mesenchymal stem (stromal) cells (MSC) tightly associated with the vertebral body bone fragment byproduct of the HPC, Marrow recovery process. Thus, these vertebral bone adherent MSC (vBA-MSC) are matched to the banked BM obtained from each donor, as opposed to third-party MSC, which enhances safety and potentially efficacy. Isolation and characterization of vBA-MSC from over 30 donors has demonstrated that the cells are no different than traditional BM-MSC; however, their abundance is >1,000-fold higher than obtainable from living donor BM aspirates. Based on our own unpublished data as well as reports published by others, MSC facilitate chimerism, especially at limiting hematopoietic stem and progenitor cell (HSPC) numbers and increase safety by controlling and/or preventing graft-vs.-host-disease (GvHD). Thus, vBA-MSC have the potential to facilitate mixed chimerism, promote complementary peripheral immunomodulatory functions and increase safety of BM infusions. Both HPC, Marrow and vBA-MSC have potential use in current VCA and solid organ transplant (SOT) tolerance clinical protocols that are amenable to "delayed tolerance." Current trials with HPC, Marrow are planned with subsequent phases to include vBA-MSC for tolerance of both VCA and SOT.

Human fetal liver MSCs are more effective than adult bone marrow MSCs for their immunosuppressive, immunomodulatory, and Foxp3+ T reg induction capacity

BACKGROUND

Mesenchymal stem cells (MSCs) exhibit active abilities to suppress or modulate deleterious immune responses by various molecular mechanisms. These cells are the subject of major translational efforts as cellular therapies for immune-related diseases and transplantations. Plenty of preclinical studies and clinical trials employing MSCs have shown promising safety and efficacy outcomes and also shed light on the modifications in the frequency and function of regulatory T cells (T regs). Nevertheless, the mechanisms underlying these observations are not well known. Direct cell contact, soluble factor production, and turning antigen-presenting cells into tolerogenic phenotypes, have been proposed to be among possible mechanisms by which MSCs produce an immunomodulatory environment for T reg expansion and activity. We and others demonstrated that adult bone marrow (BM)-MSCs suppress adaptive immune responses directly by inhibiting the proliferation of CD4+ helper and CD8+ cytotoxic T cells but also indirectly through the induction of T regs. In parallel, we demonstrated that fetal liver (FL)-MSCs demonstrates much longer-lasting immunomodulatory properties compared to BM-MSCs, by inhibiting directly the proliferation and activation of CD4+ and CD8+ T cells. Therefore, we investigated if FL-MSCs exert their strong immunosuppressive effect also indirectly through induction of T regs.

METHODS

MSCs were obtained from FL and adult BM and characterized according to their surface antigen expression, their multilineage differentiation, and their proliferation potential. Using different in vitro combinations, we performed co-cultures of FL- or BM-MSCs and murine CD3+CD25-T cells to investigate immunosuppressive effects of MSCs on T cells and to quantify their capacity to induce functional T regs.

RESULTS

We demonstrated that although both types of MSC display similar cell surface phenotypic profile and differentiation capacity, FL-MSCs have significantly higher proliferative capacity and ability to suppress both CD4+ and CD8+ murine T cell proliferation and to modulate them towards less active phenotypes than adult BM-MSCs. Moreover, their substantial suppressive effect was associated with an outstanding increase of functional CD4+CD25+Foxp3+ T regs compared to BM-MSCs.

CONCLUSIONS

These results highlight the immunosuppressive activity of FL-MSCs on T cells and show for the first time that one of the main immunoregulatory mechanisms of FL-MSCs passes through active and functional T reg induction.

Graft infusion of adipose-derived mesenchymal stromal cells to prevent rejection in experimental intestinal transplantation: A feasibility study

BACKGROUND

Mesenchymal stromal cells (MSC) have been proposed as a promising complement to standard immunosuppression in solid organ transplantation because of their immunomodulatory properties. The present work addresses the role of adipose-derived MSC (Ad-MSC) in an experimental model of acute rejection in small bowel transplantation (SBT).

MATERIAL/METHODS

Heterotopic allogeneic SBT was performed. A single dose of 1.5x106 Ad-MSC was intra-arterially delivered just before graft reperfusion. Animals were divided into CONTROL (CTRL), CONTROL+Ad-MSC (CTRL_MSC), tacrolimus (TAC), and TAC+Ad-MSC (TAC_MSC) groups. Each Ad-MSC groups was subdivided in autologous and allogeneic third-party groups.

RESULTS

Rejection rate and severity were similar in MSC-treated and untreated animals. CTRL_MSC animals showed a decrease in macrophages, T-cell (CD4, CD8, and Foxp3 subsets) and B-cell counts in the graft compared with CTRL, this decrease was attenuated in TAC_MSC animals. Pro- and anti-inflammatory cytokines and some chemokines and growth factors increased in CTRL_MSC animals, especially in the allogeneic group, whereas milder changes were seen in the TAC groups.

CONCLUSION

Ad-MSC did not prevent rejection when administered just before reperfusion. However, they showed immunomodulatory effects that could be relevant for a longer-term outcome. Interference between tacrolimus and the MSC effects should be addressed in further studies.

Childhood co-exposure of cold stress and PM2.5 aggravates the susceptibility and severity of asthma in adulthood of mice

Both cold stress and ambient fine particle particulate matter (PM_2.5 ) has been reported to aggravate and induce respiratory problems like asthma, but the mechanism involved in that has not been fully understood. Therefore, the present study is to explore the mechanism involved in the increased susceptibility and severity of asthma caused by cold stress and PM_2.5 exposure. Urban PM_2.5 of Shanghai was concentrated to simulate a PM_2.5 -polluted environment with an average concentration of 400 μg/m³ , where 1-month young C57BL/6J mice were exposed for 2 months under cold stress (2°C). Co-exposure of cold stress and PM_2.5 in childhood of mice led to significant infiltration of inflammatory cells in the peribronchial region or airspaces and the thickening or fibrosis of alveolar septum, increased OVA-specific IgE in serum and total cells, eosinophil cells, and the levels of inflammatory cytokines including IL-4, IL-8, IL-1β, IL-5, IL-13, and IFN-γ in bronchoalveolar lavage fluid (BALF) of asthma mice. Moreover, mice in co-exposure group presented a significantly high cough feature, reduced catalase (CAT), glutathione (GSH), superoxide dismutase (SOD), and elevated malonaldehyde (MDA) elevated in BALF; increased ratio of Th2/Th1 and the markable inhibition of Th17 differentiation toward Treg cells in the adulthood of asthma mice. Cold stress and PM_2.5 co-exposure in childhood may promote the deterioration of asthma symptoms in adulthood of mice by increasing inflammatory cytokines, ROS formation, Th2/Th1 imbalance, and suppressing the differentiation of Th17 toward Treg cells, which will help to provide experimental references when making some therapeutic strategies in allergic diseases through focusing on some natural solutions.

Cellular therapies in organ transplantation

Cellular therapy is a promising tool for improving the outcome of organ transplantation. Various cell types with different immunoregulatory and regenerative properties may find application for specific transplant rejection or injury-related indications. The current era is crucial for the development of cellular therapies. Preclinical models have demonstrated the feasibility of efficacious cell therapy in transplantation, early clinical trials have shown safety of several of these therapies, and the first steps towards efficacy studies in humans have been made. In this review, we address the current state of the art of cellular therapies in clinical transplantation and discuss monitoring tools and endpoints for these studies.

Induction of the IL-1RII decoy receptor by NFAT/FOXP3 blocks IL-1β-dependent response of Th17 cells

Derived from a common precursor cell, the balance between Th17 and Treg cells must be maintained within immune system to prevent autoimmune diseases. IL-1β-mediated IL-1 receptor (IL-1R) signaling is essential for Th17-cell biology. Fine-tuning of IL-1R signaling is controlled by two receptors, IL-1RI and IL-RII, IL-1R accessory protein, and IL-1R antagonist. We demonstrate that the decoy receptor, IL-1RII, is important for regulating IL-17 responses in TCR-stimulated CD4⁺ T cells expressing functional IL-1RI via limiting IL-1β responsiveness. IL-1RII expression is regulated by NFAT via its interaction with Foxp3. The NFAT/FOXP3 complex binds to the IL-1RII promoter and is critical for its transcription. Additionally, IL-1RII expression is dysregulated in CD4⁺ T cells from patients with rheumatoid arthritis. Thus, differential expression of IL-1Rs on activated CD4⁺ T cells defines unique immunological features and a novel molecular mechanism underlies IL-1RII expression. These findings shed light on the modulatory effects of IL-1RII on Th17 responses.

Immunomodulation by systemic administration of human-induced pluripotent stem cell-derived mesenchymal stromal cells to enhance the therapeutic efficacy of cell-based therapy for treatment of myocardial infarction

Rationale: Poor survival and engraftment are major hurdles of stem cell therapy in the treatment of myocardial infarction (MI). We sought to determine whether pre-transplantation systemic intravenous administration of human induced pluripotent stem cell (hiPSC)-derived mesenchymal stromal cells (hiPSC-MSCs) could improve the survival of hiPSC-MSCs or hiPSC-derived cardiomyocytes (hiPSC-CMs) following direct intramyocardial transplantation in a mouse model of MI.

Methods: Mice were randomized to undergo intravenous administration of saline or 5×10⁵ hiPSC-MSCs one week prior to MI, induced by ligation of the left anterior descending coronary artery. Mice were further assigned to undergo direct intramyocardial transplantation of hiPSC-MSCs (1×10⁶) or hiPSC-CMs (1×10⁶) 10 minutes following MI. Echocardiographic and invasive hemodynamic assessment were performed to determine cardiac function. In-vivo fluorescent imaging analysis, immunofluorescence staining and polymerase chain reaction were performed to detect cell engraftment. Flow cytometry of splenic regulatory T cells (Tregs) and natural killer (NK) cells was performed to assess the immunomodulatory effects.

Results: Pre-transplantation systemic administration of hiPSC-MSCs increased systemic Tregs activation, decreased the number of splenic NK cells and inflammation, and enhanced survival of transplanted hiPSC-MSCs and hiPSC-CMs. These improvements were associated with increased neovascularization and decreased myocardial inflammation and apoptosis at the peri-infract zone with consequent improved left ventricular function four weeks later. Co-culture of splenic CD4 cells with hiPSC-MSCs also modulated their cytokine expression profile with a decreased level of interferon-γ, tumor necrosis factor-α, and interleukin (IL)-17A, but not IL-2, IL-6 and IL-10.

Conclusion: Pre-transplantation systemic intravenous administration of hiPSC-MSCs induced immunomodulation and facilitated the survival of intramyocardially transplanted cells to improve cardiac function in MI.

Mesenchymal stem cells as living anti-inflammatory therapy for COVID-19 related acute respiratory distress syndrome

Coronavirus disease 2019 (COVID-19), a pandemic disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), is growing at an exponential rate worldwide. Manifestations of this disease are heterogeneous; however, advanced cases often exhibit various acute respiratory distress syndrome-like symptoms, systemic inflammatory reactions, coagulopathy, and organ involvements. A common theme in advanced COVID-19 is unrestrained immune activation, classically referred to as a “cytokine storm”, as well as deficiencies in immune regulatory mechanisms such as T regulatory cells. While mesenchymal stem cells (MSCs) themselves are objects of cytokine regulation, they can secrete cytokines to modulate immune cells by inducing anti-inflammatory regulatory Treg cells, macrophages and neutrophils; and by reducing the activation of T and B cells, dendritic and nature killer cells. Consequently, they have therapeutic potential for treating severe cases of COVID-19. Here we discuss the unique ability of MSCs, to act as a “living anti-inflammatory”, which can “rebalance” the cytokine/immune responses to restore equilibrium. We also discuss current MSC trials and present different concepts for optimization of MSC therapy in patients with COVID-19 acute respiratory distress syndrome. 

Comparative Proteomic Analysis Identifies EphA2 as a Specific Cell Surface Marker for Wharton's Jelly-Derived Mesenchymal Stem Cells

Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) are a valuable tool in stem cell research due to their high proliferation rate, multi-lineage differentiation potential, and immunotolerance properties. However, fibroblast impurity during WJ-MSCs isolation is unavoidable because of morphological similarities and shared surface markers. Here, a proteomic approach was employed to identify specific proteins differentially expressed by WJ-MSCs in comparison to those by neonatal foreskin and adult skin fibroblasts (NFFs and ASFs, respectively). Mass spectrometry analysis identified 454 proteins with a transmembrane domain. These proteins were then compared across the different cell-lines and categorized based on their cellular localizations, biological processes, and molecular functions. The expression patterns of a selected set of proteins were further confirmed by quantitative reverse transcription polymerase chain reaction (qRT-PCR), Western blotting, and immunofluorescence assays. As anticipated, most of the studied proteins had common expression patterns. However, EphA2, SLC25A4, and SOD2 were predominantly expressed by WJ-MSCs, while CDH2 and Talin2 were specific to NFFs and ASFs, respectively. Here, EphA2 was established as a potential surface-specific marker to distinguish WJ-MSCs from fibroblasts and for prospective use to prepare pure primary cultures of WJ-MSCs. Additionally, CDH2 could be used for a negative-selection isolation/depletion method to remove neonatal fibroblasts contaminating preparations of WJ-MSCs.