TNFα/TNFR2 signaling pathway: an active immune checkpoint for mesenchymal stem cell immunoregulatory function

CD163, a novel receptor for TNF, was revealed in situ by proximity ligation assay

Cytokine therapy utilizes cytokines to enhance the immune system to fight diseases. These strategies rely on advanced knowledge, including the communication between cytokines and their receptors. In situ, cytokine-receptor interactions are typically analyzed by co-localization using immunolabeling. Our study compared co-localization using the Proximity Ligation Assay (PLA), a recently developed in situ protein-protein interaction technique. In an inflamed porcine lung model, we demonstrated the efficacy of PLA in detecting interactions between tumor necrosis factor (TNF) and its receptors TNFR1 and TNFR2. Additionally, the CD163 receptor was identified as a novel partner of TNF. Furthermore, the combination of immunolabeling and PLA offered additional insights, particularly, the internalization of TNF following its binding with CD163 in macrophages. Our work focused on in situ interactions of TNF with macrophages TNF receptors and suggested exciting perspectives for further understanding and application of cytokine-based therapies.

In situ blockade of TNF-TNFR2 axis via oncolytic adenovirus improves antitumor efficacy in solid tumors

Tumor necrosis factor (TNF) has been recognized as an immune activation factor in tumor immunotherapy. Our study demonstrated that TNF blockade markedly enhanced the antitumor efficacy of oncolytic adenovirus (AdV) therapy. To minimize systemic side effects, we engineered a recombinant oncolytic AdV encoding a TNF inhibitor (AdV-TNFi) to confine TNF blockade within the tumor microenvironment (TME). AdV-TNFi significantly improved therapeutic outcomes across various solid tumor models, including four murine and two golden hamster cancers. Immune cell profiling identified CD8+ T cells as the primary mediators of AdV-TNFi-induced antitumor effects, rather than CD4+ T or NK cells. Additionally, AdV-TNFi significantly decreased the infiltration of suppressive myeloid-derived immune cells within the TME and promoted long-term antitumor immune surveillance. Further investigation indicated that TNFR2, more than TNFR1, is pertinent to the immunosuppressive TME, with a recombinant AdV-encoding anti-TNFR2 demonstrating comparable antitumor efficacy to AdV-TNFi. Moreover, AdV-TNFi enhanced the antitumor efficacy of gemcitabine and immune checkpoint blockades (ICBs), such as anti-PD-L1 and anti-TIGIT antibodies, in pancreatic carcinoma and the anti-EGFR antibody in colon carcinoma. In conclusion, intratumoral blockade of the TNF/TNFR2 axis using AdV augments cancer immunotherapy efficacy while mitigating the risks associated with systemic TNF or TNFR2 suppression, warranting further clinical investigation.

The effects of prenatal administration of tumor necrosis factor-α on osteocalcin and RANK expression in newborn mice

Tumor necrosis factor-α (TNF-α) induces a multitude of actions and consequences in bone and cartilage resorption and immune response augmentation. In this research, we aimed to investigate the effects of TNF-α on osteogenesis parameters in newborn mice. Experimental research was conducted on 42 pregnant mice, dividing into seven groups as follows: control (no injection), vehicle 1 (PBS injection on 7-9th pregnancy days (PD)), vehicle 2 (PBS injection during pregnancy), experimental 1 (injection of 10 ng/kg of TNF-α on 7-9th PD), experimental 2 (injection of 100 ng/kg of TNF-α on 7-9th PD), experimental 3 (injection of 10 ng/kg of TNF-α during pregnancy) and experimental 4 (injection of 100 ng/kg of TNF-α during pregnancy). Immunohistochemical and histomorphologic studies were performed on right lower limb of newborn mice. The expression of osteocalcin and RANK markers and cortical bone thickness showed no significant difference between the groups. There were no significant changes in osteogenesis parameters in this study. Some evidences have demonstrated the dual role of TNF-α on body tissues. However, future investigations should be done to analyze the molecular pathways involved in TNF-α functions and assess the paradoxical effects of TNF-α on osteogenesis.

The implications of the TNFα-TNFR2 immune checkpoint signaling pathway in cancer treatment: From immunoregulation to angiogenesis

Despite the tremendous advances that have been made in biomedical research, cancer remains one of the leading causes of death worldwide. Several therapeutic approaches have been suggested and applied to treat cancer with impressive results. Immunotherapy based on targeting immune checkpoint signaling pathways proved to be one of the most efficient. In this review article, we will focus on the recently discovered TNFα-TNFR2 signaling pathway, which controls the immunological and pro-angiogenic properties of many immunoregulatory and pro-angiogenic cells such as endothelial progenitor cells (EPCs), mesenchymal stem cells (MSCs), and regulatory T cells (Tregs). Due to their biological properties, these cells can play a major role in cancer progression and metastasis. Therefore, we will discuss the advantages and disadvantages of an anti-TNFR2 treatment that could carry two faces under one hood. It interrupts the immunosuppressive and pro-angiogenic behaviors of the above-mentioned cells and interferes with tumor growth and survival.

Tumor Necrosis Factor Receptor 1 Is Required for Human Umbilical Cord-Derived Mesenchymal Stem Cell-Mediated Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is a systemic, chronic inflammatory disease characterized by altered levels of inflammatory cytokines. One of the key cytokines involved in the pathogenesis of RA is tumor necrosis factor α (TNF-α), which plays a crucial role in the differentiation of T cells and B cells and serves as a primary trigger of inflammation and joint damage in RA. Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) have shown potential in alleviating the symptoms of RA. Previous in vitro studies indicate that TNF-α secreted by T cells can activate NF-κB in human MSCs, thereby triggering the immunoregulatory capacity of MSCs in a manner dependent on tumor necrosis factor receptor 1 (TNFR1). Inspired by these findings, we aimed to evaluate whether TNFR1 determine the therapeutic effects of hUC-MSCs on RA. First, we investigated whether TNFR1 is necessary for hUC-MSCs to inhibit TNF-α production of PBMCs, a source of elevated TNF-α in patients. Through coculture experiment, we confirmed that this inhibition was dependent on TNFR1. Subsequently, we administered hUC-MSCs or siTNFR1-MSCs to DBA/1J male mice with collagen-induced arthritis. The results indicated that hUC-MSCs significantly alleviated the pathological features of RA and suppressed the inflammatory cytokines IFN-γ, TNF-α, and IL-6 in peripheral blood, also in a manner dependent on TNFR1 either. Given the dramatic pathologic differences between hUC-MSCs and siTNFR1-MSCs treatments, we questioned whether production of growth factors and chemokines was significantly influenced by TNFR1. Consequently, we stimulated hUC-MSCs or siTNFR1-MSCs through IFN-γ, TNF-α, and IL-6, and profiled growth factors and chemokines in serum, which revealed significant changes of hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF), as well as chemokines CXCL9, CXCL10, IL-8, and RANTES. In summary, our findings suggest that TNFR1 may determine whether hUC-MSCs will gain abilities of anti-inflammation and tissue regeneration.

Understanding the role of TNFR2 signaling in the tumor microenvironment of breast cancer

Breast cancer (BC) is the most frequently diagnosed malignancy among women. It is characterized by a high level of heterogeneity that emerges from the interaction of several cellular and soluble components in the tumor microenvironment (TME), such as cytokines, tumor cells and tumor-associated immune cells. Tumor necrosis factor (TNF) receptor 2 (TNFR2) appears to play a significant role in microenvironmental regulation, tumor progression, immune evasion, drug resistance, and metastasis of many types of cancer, including BC. However, the significance of TNFR2 in BC biology is not fully understood. This review provides an overview of TNFR2 biology, detailing its activation and its interactions with important signaling pathways in the TME (e.g., NF-κB, MAPK, and PI3K/Akt pathways). We discuss potential therapeutic strategies targeting TNFR2, with the aim of enhancing the antitumor immune response to BC. This review provides insights into role of TNFR2 as a major immune checkpoint for the future treatment of patients with BC.

Engineering mesenchymal stem cells for premature ovarian failure: overcoming challenges and innovating therapeutic strategies

Premature ovarian failure (POF) is a leading cause of infertility in women, causing significant psychological and physical distress. Current therapeutic options are limited, necessitating the exploration of new treatments. Mesenchymal stem cells (MSCs), known for their remarkable homing and regenerative properties, have emerged as a promising intervention for POF. However, their clinical efficacy has been inconsistent. This paper aims to address these challenges by examining the cellular heterogeneity within MSC populations, which is crucial for identifying and selecting specific functional subpopulations for clinical applications. Understanding this heterogeneity can enhance therapeutic efficacy and ensure treatment stability. Additionally, this review comprehensively examines the literature on the effectiveness, safety, and ethical considerations of MSCs for ovarian regeneration, with a focus on preclinical and clinical trials. We also discuss potential strategies involving genetically and tissue-engineered MSCs. By integrating insights from these studies, we propose new directions for the design of targeted MSC treatments for POF and related disorders, potentially improving outcomes, addressing safety concerns, and expanding therapeutic options while ensuring ethical compliance.

Therapeutic effect of three-dimensional hanging drop cultured human umbilical cord mesenchymal stem cells on osteoarthritis in rabbits

BACKGROUND

Mesenchymal stem cells (MSCs) have shown a positive effect on Osteoarthritis (OA), but the efficacy is still not significant in clinical. Conventional two-dimensional (2D) monolayer culture method is prone to cause MSCs undergoing replication senescence, which may affect the functions of MSCs. Three-dimensional (3D) culture strategy can sustain cell proliferative capacity and multi-differentiation potential. This study aimed to investigate the therapeutic potential of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) cultured by 3D hanging drop method on OA.

METHODS

hUC-MSCs were isolated from umbilical cord and cultured by 3D hanging drop method for 48 h. Scanning electron microscopy (SEM) was used to observe gross morphology 2D and 3D hUC-MSCs. Transcriptome comparison of gene expression differences between 2D and 3D hUC-MSCs. GO enrichment analysis, KEGG pathway enrichment analysis and GSEA enrichment analysis were used to analyze the impact of 3D hanging drop culture on the biological functions of hUC-MSCs. Female New Zealand rabbits (n = 12) were divided into 4 groups: Normal group, Model group, 2D hUC-MSCs treatment group and 3D hUC-MSCs treatment group. After 8 weeks, the gross and histological appearance of the cartilage was evaluated by safranin O-fast green staining and Mankin scoring system. The expression of type I collagen and type II collagen was detected by immunohistochemistry. The levels of IL-6, IL-7, TNFα, TGFβ1 and IL-10 in the knee joint fluid were tested by ELISA.

RESULTS

3D hanging drop culture changed cell morphology but did not affect phenotype. The MSCs transcriptome profiles showed that 3D hanging drop culture method enhanced cell-cell contact, improved cell responsiveness to external stimuli and immunomodulatory function. The animal experiment results showed that hUC-MSCs could promote cartilage regeneration compared with Model group. 3D hUC-MSCs treatment group had a higher histological score and significantly increased type II collagen secretion. In addition, 3D hUC-MSCs treatment group increased the expression of anti-inflammatory factors TGFβ1 and IL-10.

CONCLUSION

The above experimental results illustrated that 3D hanging drop culture method could enhance the therapeutic effect of hUC-MSCs, and showed a good clinical application prospect in the treatment of OA.

Targeting TNFR2 for cancer immunotherapy: recent advances and future directions

Cancer is the leading cause of death worldwide, accounting for nearly 10 million deaths every year. Immune checkpoint blockade approaches have changed the therapeutic landscape for many tumor types. However, current immune checkpoint inhibitors PD-1 or CTLA-4 are far from satisfactory, due to high immune-related adverse event incident (up to 60%) and the inefficiency in cases of "cold" tumor microenvironment. TNFR2, a novel hopeful tumor immune target, was initially proposed in 2017. It not only promotes tumor cell proliferation, but also correlates with the suppressive function of Treg cells, implicating in the development of an immunosuppressive tumor microenvironment. In preclinical studies, TNFR2 antibody therapy has demonstrated efficacy alone or a potential synergistic effect when combined with classical PD-1/ CTLA-4 antibodies. The focus of this review is on the characteristics, functions, and recent advancements in TNFR2 therapy, providing a new direction for the next generation of anti-tumor alternative therapy.

Therapeutic and immunomodulatory potentials of mesenchymal stromal/stem cells and immune checkpoints related molecules

Mesenchymal stromal/stem cells (MSCs) are used in many studies due to their therapeutic potential, including their differentiative ability and immunomodulatory properties. These cells perform their therapeutic functions by using various mechanisms, such as the production of anti-inflammatory cytokines, growth factors, direct cell-to-cell contact, extracellular vesicles (EVs) production, and mitochondrial transfer. However, mechanisms related to immune checkpoints (ICPs) and their effect on the immunomodulatory ability of MSCs are less discussed. The main function of ICPs is to prevent the initiation of unwanted responses and to regulate the immune system responses to maintain the homeostasis of these responses. ICPs are produced by various types of immune system regulatory cells, and defects in their expression and function may be associated with excessive responses that can ultimately lead to autoimmunity. Also, by expressing different types of ICPs and their ligands (ICPLs), tumor cells prevent the formation and durability of immune responses, which leads to tumors' immune escape. ICPs and ICPLs can be produced by MSCs and affect immune cell responses both through their secretion into the microenvironment or direct cell-to-cell interaction. Pre-treatment of MSCs in inflammatory conditions leads to an increase in their therapeutic potential. In addition to the effect that inflammatory environments have on the production of anti-inflammatory cytokines by MSCs, they can increase the expression of various types of ICPLs. In this review, we discuss different types of ICPLs and ICPs expressed by MSCs and their effect on their immunomodulatory and therapeutic potential.

Tumor necrosis factor α promotes clonal dominance of KIT D816V+ cells in mastocytosis: role of survivin and impact on prognosis

ABSTRACT

Systemic mastocytosis (SM) is defined by the expansion and accumulation of neoplastic mast cells (MCs) in the bone marrow (BM) and extracutaneous organs. Most patients harbor a somatic KIT D816V mutation, which leads to growth factor-independent KIT activation and accumulation of MC. Tumor necrosis factor α (TNF) is a proapoptotic and inflammatory cytokine that has been implicated in the clonal selection of neoplastic cells. We found that KIT D816V increases the expression and secretion of TNF. TNF expression in neoplastic MCs is reduced by KIT-targeting drugs. Similarly, knockdown of KIT or targeting the downstream signaling cascade of MAPK and NF-κB signaling reduced TNF expression levels. TNF reduces colony formation in human BM cells, whereas KIT D816V+ cells are less susceptible to the cytokine, potentially contributing to clonal selection. In line, knockout of TNF in neoplastic MC prolonged survival and reduced myelosuppression in a murine xenotransplantation model. Mechanistic studies revealed that the relative resistance of KIT D816V+ cells to TNF is mediated by the apoptosis-regulator BIRC5 (survivin). Expression of BIRC5 in neoplastic MC was confirmed by immunohistochemistry of samples from patients with SM. TNF serum levels are significantly elevated in patients with SM and high TNF levels were identified as a biomarker associated with inferior survival. We here characterized TNF as a KIT D816V-dependent cytokine that promotes clonal dominance. We propose TNF and apoptosis-associated proteins as potential therapeutic targets in SM.

Design of a Stem Cell-Based Therapy for Ependymal Repair in Hydrocephalus Associated With Germinal Matrix Hemorrhages

BACKGROUND

In preterm birth germinal matrix hemorrhages (GMHs) and the consequent posthemorrhagic hydrocephalus (PHH), the neuroepithelium/ependyma development is disrupted. This work is aimed to explore the possibilities of ependymal repair in GMH/PHH using a combination of neural stem cells, ependymal progenitors (EpPs), and mesenchymal stem cells.

METHODS

GMH/PHH was induced in 4-day-old mice using collagenase, blood, or blood serum injections. PHH severity was characterized 2 weeks later using magnetic resonance, immunofluorescence, and protein expression quantification with mass spectrometry. Ependymal restoration and wall regeneration after stem cell treatments were tested in vivo and in an ex vivo experimental approach using ventricular walls from mice developing moderate and severe GMH/PHH. The effect of the GMH environment on EpP differentiation was tested in vitro. Two-tailed Student t or Wilcoxon-Mann-Whitney U test was used to find differences between the treated and nontreated groups. ANOVA and Kruskal-Wallis tests were used to compare >2 groups with post hoc Tukey and Dunn multiple comparison tests, respectively.

RESULTS

PHH severity was correlated with the extension of GMH and ependymal disruption (means, 88.22% severe versus 19.4% moderate). GMH/PHH hindered the survival rates of the transplanted neural stem cells/EpPs. New multiciliated ependymal cells could be generated from transplanted neural stem cells and more efficiently from EpPs (15% mean increase). Blood and TNFα (tumor necrosis factor alpha) negatively affected ciliogenesis in cells committed to ependyma differentiation (expressing Foxj1 [forkhead box J1] transcription factor). Pretreatment with mesenchymal stem cells improved the survival rates of EpPs and ependymal differentiation while reducing the edematous (means, 18% to 0.5% decrease in severe edema) and inflammatory conditions in the explants. The effectiveness of this therapeutical strategy was corroborated in vivo (means, 29% to 0% in severe edema).

CONCLUSIONS

In GMH/PHH, the ependyma can be restored and edema decreased from either neural stem cell or EpP transplantation in vitro and in vivo. Mesenchymal stem cell pretreatment improved the success of the ependymal restoration.

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.

Generic design principles for antibody-based tumour necrosis factor (TNF) receptor 2 (TNFR2) agonists with FcγR-independent agonism

Background: Selective TNFR2 activation can be used to treat immune pathologies by activating and expanding regulatory T-cells (Tregs) but may also restore anti-tumour immunity by co-stimulating CD8+ T-cells. Oligomerized TNFR2-specific TNF mutants or anti-TNFR2 antibodies can activate TNFR2 but suffer either from poor production and pharmacokinetics or in the case of anti-TNFR2 antibodies typically from the need of FcγR binding to elicit maximal agonistic activity. Methods: To identify the major factor(s) determining FcγR-independent agonism of anti-TNFR2 antibodies, we systematically investigated a comprehensive panel of anti-TNFR2 antibodies and antibody-based constructs differing in the characteristics of their TNFR2 binding domains but also in the number and positioning of the latter. Results: We identified the domain architecture of the constructs as the pivotal factor enabling FcγR-independent, thus intrinsic TNFR2-agonism. Anti-TNFR2 antibody formats with either TNFR2 binding sites on opposing sites of the antibody scaffold or six or more TNFR2 binding sites in similar orientation regularly showed strong FcγR-independent agonism. The affinity of the TNFR2 binding domain and the epitope recognized in TNFR2, however, were found to be of only secondary importance for agonistic activity. Conclusion: Generic design principles enable the generation of highly active bona fide TNFR2 agonists from nearly any TNFR2-specific antibody.

TNF and TNF receptors as therapeutic targets for rheumatic diseases and beyond

The cytokine TNF signals via two distinct receptors, TNF receptor 1 (TNFR1) and TNFR2, and is a central mediator of various immune-mediated diseases. Indeed, TNF-neutralizing biologic drugs have been in clinical use for the treatment of many inflammatory pathological conditions, including various rheumatic diseases, for decades. TNF has pleiotropic effects and can both promote and inhibit pro-inflammatory processes. The integrated net effect of TNF in vivo is a result of cytotoxic TNFR1 signalling and the stimulation of pro-inflammatory processes mediated by TNFR1 and TNFR2 and also TNFR2-mediated anti-inflammatory and tissue-protective activities. Inhibition of the beneficial activities of TNFR2 might explain why TNF-neutralizing drugs, although highly effective in some diseases, have limited benefit in the treatment of other TNF-associated pathological conditions (such as graft-versus-host disease) or even worsen the pathological condition (such as multiple sclerosis). Receptor-specific biologic drugs have the potential to tip the balance from TNFR1-mediated activities to TNFR2-mediated activities and enable the treatment of diseases that do not respond to current TNF inhibitors. Accordingly, a variety of reagents have been developed that either selectively inhibit TNFR1 or selectively activate TNFR2. Several of these reagents have shown promise in preclinical studies and are now in, or approaching, clinical trials.

Effects of Modified Glucosamine on the Chondrogenic Potential of Circulating Stem Cells under Experimental Inflammation

Glucosamine (GlcN) is a glycosaminoglycan (GAGs) constituent in connective tissues. It is naturally produced by our body or consumed from diets. In the last decade, in vitro and in vivo trials have demonstrated that the administration of GlcN or its derivates has a protective effect on cartilage when the balance between catabolic and anabolic processes is disrupted and cells are no longer able to fully compensate for the loss of collagen and proteoglycans. To date, these benefits are still controversial because the mechanism of action of GlcN is not yet well clarified. In this study, we have characterized the biological activities of an amino acid (AA) derivate of GlcN, called DCF001, in the growth and chondrogenic induction of circulating multipotent stem cells (CMCs) after priming with tumor necrosis factor-alpha (TNFα), a pleiotropic cytokine commonly expressed in chronic inflammatory joint diseases. In the present work, stem cells were isolated from the human peripheral blood of healthy donors. After priming with TNFα (10 ng/mL) for 3 h, cultures were treated for 24 h with DCF001 (1 μg/mL) dissolved in a proliferative (PM) or chondrogenic (CM) medium. Cell proliferation was analyzed using a Corning^® Cell Counter and trypan blue exclusion technique. To evaluate the potentialities of DCF001 in counteracting the inflammatory response to TNFα, we measured the amount of extracellular ATP (eATP) and the expression of adenosine-generating enzymes CD39/CD73, TNFα receptors, and NF-κB inhibitor IκBα using flow cytometry. Finally, total RNA was extracted to perform a gene expression study of some chondrogenic differentiation markers (COL2A1, RUNX2, and MMP13). Our analysis has shed light on the ability of DCF001 to (a) regulate the expression of CD39, CD73, and TNF receptors; (b) modulate eATP under differentiative induction; (c) enhance the inhibitory activity of IκBα, reducing its phosphorylation after TNFα stimulation; and (d) preserve the chondrogenic potentialities of stem cells. Although preliminary, these results suggest that DCF001 could be a valuable supplement for ameliorating the outcome of cartilage repair interventions, enhancing the efficacy of endogenous stem cells under inflammatory stimuli.

Immunomodulation for Tissue Repair and Regeneration

Various immune cells participate in repair and regeneration following tissue injury or damage, orchestrating tissue inflammation and regeneration processes. A deeper understanding of the immune system's involvement in tissue repair and regeneration is critical for the development of successful reparatory and regenerative strategies. Here we review recent technologies that facilitate cell-based and biomaterial-based modulation of the immune systems for tissue repair and regeneration. First, we summarize the roles of various types of immune cells in tissue repair. Second, we review the principle, examples, and limitations of regulatory T (Treg) cell-based therapy, a representative cell-based immunotherapy. Finally, we discuss biomaterial-based immunotherapy strategies that aim to modulate immune cells using various biomaterials for tissue repair and regeneration.

Macrophage–Neuroglia Interactions in Promoting Neuronal Regeneration in Zebrafish

The human nervous system exhibits limited regenerative capabilities following damage to the central nervous system (CNS), leading to a scarcity of effective treatments for nerve function recovery. In contrast, zebrafish demonstrate remarkable regenerative abilities, making them an ideal model for studying the modulation of inflammatory processes after injury. Such research holds significant translational potential to enhance our understanding of recovery from damage and disease. Macrophages play a crucial role in tissue repair and regeneration, with their subpopulations indirectly promoting axonal regeneration through developmental signals. The AP-1 signaling pathway, mediated by TNF/Tnfrsf1a, can elevate HDAC1 expression and facilitate regeneration. Furthermore, following spinal cord injury (SCI), pMN progenitors have been observed to switch between oligodendrocyte and motor neuron fates, with macrophage-secreted TNF-α potentially regulating the differentiation of ependymal–radial glia progenitors and oligodendrocytes. Radial glial cells (RGs) are also essential for CNS regeneration in zebrafish, as they perform neurogenesis and gliogenesis, with specific RG subpopulations potentially existing for the generation of neurons and oligodendrocytes. This review article underscores the critical role of macrophages and their subpopulations in tissue repair and regeneration, focusing on their secretion of TNF-α, which promotes axonal regeneration in zebrafish. We also offer insights into the molecular mechanisms underlying TNF-α’s ability to facilitate axonal regeneration and explore the potential of pMN progenitor cells and RGs following SCI in zebrafish. The review concludes with a discussion of various unresolved questions in the field, and ideas are suggested for future research. Studying innate immune cell interactions with neuroglia following injury may lead to the development of novel strategies for treating the inflammatory processes associated with regenerative medicine, which are commonly observed in injury and disease.

Gut region-specific TNFR expression: TNFR2 is more affected than TNFR1 in duodenal myenteric ganglia of diabetic rats

BACKGROUND

Cytokines are essential in autoimmune inflammatory processes that accompany type 1 diabetes. Tumor necrosis factor alpha plays a key role among others in modulating enteric neuroinflammation, however, it has a dual role in cell degeneration or survival depending on different TNFRs. In general, TNFR1 is believed to trigger apoptosis, while TNFR2 promotes cell regeneration. The importance of the neuronal microenvironment has been recently highlighted in gut region-specific diabetic enteric neuropathy, however, the expression and alterations of different TNFRs in the gastrointestinal tract has not been reported.

AIM

To investigate the TNFR1 and TNFR2 expression in myenteric ganglia and their environment in different intestinal segments of diabetic rats.

METHODS

Ten weeks after the onset of hyperglycemia, gut segments were taken from the duodenum, ileum and colon of streptozotocin-induced (60 mg/body weight kg i.p.) diabetic (n = 17), insulin-treated diabetic (n = 15) and sex- and age-matched control (n = 15) rats. Myenteric plexus whole-mount preparations were prepared from different gut regions for TNFR1/HuCD or TNFR2/HuCD double-labeling fluorescent immunohistochemistry. TNFR1 and TNFR2 expression was evaluated by post-embedding immunogold electron microscopy on ultrathin sections of myenteric ganglia. TNFRs levels were measured by enzyme-linked immun-osorbent assay in muscle/myenteric plexus-containing (MUSCLE-MP) tissue homogenates from different gut segments and experimental conditions.

RESULTS

A distinct region-dependent TNFRs expression was detected in controls. The density of TNFR1-labeling gold particles was lowest, while TNFR2 density was highest in duodenal ganglia and a decreased TNFRs expression from proximal to distal segments was observed in MUSCLE-MP homogenates. In diabetics, the TNFR2 density was only significantly altered in the duodenum with decrease in the ganglia (0.32 ± 0.02 vs 0.45 ± 0.04, P < 0.05), while no significant changes in TNFR1 density was observed. In diabetic MUSCLE-MP homogenates, both TNFRs levels significantly decreased in the duodenum (TNFR1: 4.06 ± 0.65 vs 20.32 ± 3.1, P < 0.001; TNFR2: 11.72 ± 0.39 vs 15.91 ± 1.04, P < 0.01), which markedly influenced the TNFR2/TNFR1 proportion in both the ganglia and their muscular environment. Insulin treatment had controversial effects on TNFR expression.

CONCLUSION

Our findings show diabetes-related region-dependent changes in TNFR expression and suggest that TNFR2 is more affected than TNFR1 in myenteric ganglia in the duodenum of type 1 diabetic rats.

Elevation of circulating TNF receptor 2 in cancer: A systematic meta-analysis for its potential as a diagnostic cancer biomarker

High Tumor Necrosis Factor Receptor 2 (TNFR2) expression is characteristic of diverse malignant cells during tumorigenesis. The protein is also expressed by many immunosuppressive cells during cancer development, allowing cancer immune escape. A growing body of evidence further suggests a correlation between the circulating form of this protein and cancer development. Here we conducted a systematic meta-analysis of cancer studies published up until 1st October 2022, in which the circulating soluble TNFR2 (sTNFR2) concentrations in patients with cancers were recorded and their association with cancer risk was assessed. Of the 14,615 identified articles, 44 studies provided data on the correlation between cancer risk and the level of circulating sTNFR2. The pooled means comparison showed a consistently significant increase in the levels of sTNFR2 in diverse cancers when compared to healthy controls. These included colorectal cancer, ovarian cancer, breast cancer, non-Hodgkin's lymphoma, Hodgkin's lymphoma, lung cancer, hepatocarcinoma, and glioblastoma. In a random-effect meta-analysis, the cancer-specific odd ratios (OR) showed significant correlations between increased circulating sTNFR2 levels and the risk of colorectal cancer, non-Hodgkin's lymphoma, and hepatocarcinoma at 1.59 (95% CI:1.20-2.11), 1.98 (95% CI:1.49-2.64) and 4.32 (95% CI:2.25-8.31) respectively. The overall result showed an association between circulating levels of sTNFR2 and the risk of developing cancer at 1.76 (95% CI:1.53-2.02). This meta-analysis supports sTNFR2 as a potential diagnostic biomarker for cancer, albeit with different predictive strengths for different cancer types. This is consistent with a potential key role for TNFR2 involvement in cancer development.

The Function and Therapeutic Implications of TNF Signaling in MDSCs

Myeloid-derived suppressor cells (MDSCs) are a group of immature and heterogeneous myeloid cells with immunosuppressive functions. MDSCs play important roles in the pathogenesis of cancer, chronic inflammatory diseases, and many autoimmune disorders. The accumulation and activation of MDSCs can be regulated by tumor necrosis factor α (TNF-α). In this review, we summarize the roles played by TNF-α in the recruitment, immunosuppressive functions, and chemotaxis of MDSCs, and discuss the potential therapeutic effects of TNF-α upon these cells in tumor growth and some inflammatory disorders.

Silencing SIRT5 induces the senescence of UCB-MSCs exposed to TNF-α by reduction of fatty acid β-oxidation and anti-oxidation

Tumor necrosis factor-α (TNF-α) is an inflammatory cytokine involved in cell survival, apoptosis, and homeostasis. However, the regulatory effect of TNF-α on mesenchymal stem cell (MSC) redox regulation remains unknown. The process of delaying the senescence of MSCs and maintaining antioxidation mechanism is important in transplantation therapy to treat inflammatory diseases that result from restricted immunomodulatory effects of senescent MSCs. Thus, we examined the role of TNF-α-mediated signaling and its regulatory mechanisms on the senescence of umbilical cord blood-derived MSCs (UCB-MSCs) and identified its therapeutic efficacy in a collagen-induced arthritis (CIA) mouse model. We found that TNF-α increased fatty acid synthesis and lipid droplet (LD) formation through NF-κB/SREBP1-mediated FASN, SCD1, and DGAT2 expression, which protects UCB-MSCs from oxidative stress against accumulated toxic lipids. Additionally, DGAT2-mediated LD formation was regulated by TNF-α-activated TNF receptor (TNFR)1 signaling. We also found that storage of unsaturated FAs in LDs is regulated by SIRT5-dependent β-oxidation of FAs, which reduces mitochondrial ROS (mtROS) accumulation. Particularly, mtROS homeostasis was maintained by superoxide dismutase 2 (SOD2) upregulation through TNFR2-mediated SIRT5/Nrf2 signaling. In a CIA mouse model, UCB-MSCs transfected with SIRT5 siRNA exhibited reduced therapeutic effects compared with UCB-MSCs transfected with NT siRNA. Overall, the results indicated that SIRT5 plays a central role in protecting TNF-α-induced UCB-MSC senescence through FA β-oxidation and SOD2-mediated antioxidation.

Mesenchymal stroma/stem cells: Haematologists' friend or foe?

Mesenchymal stromal cells (MSCs) are non-haematopoietic cells found in fetal and adult organs, that play important roles in tissue repair, inflammation and immune modulation. MSCs residing in the bone marrow interact closely with haematopoietic cells and comprise an important component of the microenvironment supporting haematopoiesis, in both health and disease states. Since their identification in 1970, basic scientific and preclinical research efforts have shed light on the role of MSCs in the regulation of haematopoiesis and evoked interest in their clinical application in haematopoietic stem cell transplantation (HSCT) and malignant haematology. Over the last two decades, these research efforts have led to numerous clinical trials, which have established the safety of MSC therapy; however, the optimal mode of administration and the benefit remain inconclusive. In this paper, we will review the clinical experience with use of MSCs in HSCT for enhancement of engraftment, prevention and treatment of graft-versus-host disease and haemorrhagic cystitis. Then, we will discuss the contradictory evidence regarding tumour-promoting versus tumour-suppressing effects of MSCs in haematological malignancies, which may have relevance for future clinical applications.

Global scientific trends on the immunomodulation of mesenchymal stem cells in the 21st century: A bibliometric and visualized analysis

Background

Since the discovery of the immunomodulatory functions of mesenchymal stem cells (MSCs), their application in immunomodulation has attracted considerable attention, and an increasing number of studies have been conducted worldwide. Our research aimed to investigate the global status and trends in this field.

Methods

Publications on the immunomodulatory functions of MSCs from 1 January 2000 to 7 March 2022 were retrieved from the Web of Science Core Collection. The data were studied and indexed using the bibliometric methodology. Visualization analysis, co-authorship, co-occurrence analysis, and publication trends in MSC immunomodulation were conducted using the VOSviewer software.

Results

In total, 4,227 papers were included in the study. The number of publications and research interests has significantly increased globally. China published the highest number of related articles, while the US published articles with the highest number of citations. Stem Cell Research & Therapy had the highest number of publications. Sun Yat-sen University, Shanghai Jiao Tong University, Harvard University, and Seoul National University were the most contributive institutions. Furthermore, the studies were divided into four research hotspots for MSC immunomodulation: MSC immunomodulation in regenerative medicine, the effects and mechanisms of MSC immunomodulation, MSC therapy for immune diseases, and the cell source of MSCs.

Conclusion

This study indicates that the number of publications on MSC immunomodulation will increase in the future, and MSC immunomodulation mechanisms and clinical applications of MSC immunotherapy should be the next hotspots in this research field.

Adipose-derived stem cells attenuate acne-related inflammation via suppression of NLRP3 inflammasome

BACKGROUND

Acne is a chronic facial disease caused by Propionibacterium acnes, which proliferates within sebum-blocked skin follicles and increases inflammatory cytokine production. Several therapeutic drugs and products have been proposed to treat acne, yet no single treatment that ensures long-term treatment efficacy for all patients is available. Here, we explored the use of facial autologous fat transplant of adipose-derived stem cells (ADSCs) to dramatically reduce acne lesions.

METHODS

THP-1 cells were treated with active P. acnes for 24 h at different multiplicities of infection, and alterations in inflammatory factors were detected. To study the effect of THP-1 on inflammasome-related proteins, we first co-cultured ADSCs with THP-1 cells treated with P. acnes and evaluated the levels of these proteins in the supernatant. Further, an acne mouse model injected with ADSCs was used to assess inflammatory changes.

RESULTS

Propionibacterium acnes-mediated stimulation of THP-1 cells had a direct correlation with the expression of active caspase-1 and interleukin (IL)-1β in an infection-dependent manner. ADSCs significantly reduced the production of IL-1β induced by P. acnes stimulation through the reactive oxygen species (ROS)/Nod-like receptor family pyrin domain-containing 3 (NLRP3)/caspase-1 pathway. The results showed that ADSCs inhibit the skin inflammation induced by P. acnes by blocking the NLRP3 inflammasome via reducing the secretion of IL-1β in vivo.

CONCLUSIONS

Our findings suggest that ADSCs can alter IL-1β secretion by restricting the production of mitochondria ROS, thereby inhibiting the NLRP3/caspase-1 pathway in P. acnes-induced inflammatory responses. This study indicates that anti-acne therapy can potentially be developed by targeting the NLRP3 inflammasome.

Stem cells differentiation into insulin-producing cells (IPCs): recent advances and current challenges

Type 1 diabetes mellitus (T1D) is a chronic disease characterized by an autoimmune destruction of insulin-producing β-pancreatic cells. Although many advances have been achieved in T1D treatment, current therapy strategies are often unable to maintain perfect control of glycemic levels. Several studies are searching for new and improved methodologies for expansion of β-cell cultures in vitro to increase the supply of these cells for pancreatic islets replacement therapy. A promising approach consists of differentiation of stem cells into insulin-producing cells (IPCs) in sufficient number and functional status to be transplanted. Differentiation protocols have been designed using consecutive cytokines or signaling modulator treatments, at specific dosages, to activate or inhibit the main signaling pathways that control the differentiation of induced pluripotent stem cells (iPSCs) into pancreatic β-cells. Here, we provide an overview of the current approaches and achievements in obtaining stem cell-derived β-cells and the numerous challenges, which still need to be overcome to achieve this goal. Clinical translation of stem cells-derived β-cells for efficient maintenance of long-term euglycemia remains a major issue. Therefore, research efforts have been directed to the final steps of in vitro differentiation, aiming at production of functional and mature β-cells and integration of interdisciplinary fields to generate efficient cell therapy strategies capable of reversing the clinical outcome of T1D.

Tumor Necrosis Factor Receptor 2 (TNFR2): An Emerging Target in Cancer Therapy

Despite the great success of TNF blockers in the treatment of autoimmune diseases and the identification of TNF as a factor that influences the development of tumors in many ways, the role of TNFR2 in tumor biology and its potential suitability as a therapeutic target in cancer therapy have long been underestimated. This has been fundamentally changed with the identification of TNFR2 as a regulatory T-cell (Treg)-stimulating factor and the general clinical breakthrough of immunotherapeutic approaches. However, considering TNFR2 as a sole immunosuppressive factor in the tumor microenvironment does not go far enough. TNFR2 can also co-stimulate CD8⁺ T-cells, sensitize some immune and tumor cells to the cytotoxic effects of TNFR1 and/or acts as an oncogene. In view of the wide range of cancer-associated TNFR2 activities, it is not surprising that both antagonists and agonists of TNFR2 are considered for tumor therapy and have indeed shown overwhelming anti-tumor activity in preclinical studies. Based on a brief summary of TNFR2 signaling and the immunoregulatory functions of TNFR2, we discuss here the main preclinical findings and insights gained with TNFR2 agonists and antagonists. In particular, we address the question of which TNFR2-associated molecular and cellular mechanisms underlie the observed anti-tumoral activities of TNFR2 agonists and antagonists.

Notoginsenoside R1 Promotes Migration, Adhesin, Spreading, and Osteogenic Differentiation of Human Adipose Tissue-Derived Mesenchymal Stromal Cells

Cellular activities, such as attachment, spreading, proliferation, migration, and differentiation are indispensable for the success of bone tissue engineering. Mesenchymal stromal cells (MSCs) are the key precursor cells to regenerate bone. Bioactive compounds from natural products had shown bone regenerative potential. Notoginsenoside R1 (NGR1) is a primary bioactive natural compound that regulates various biological activities, including cardiovascular protection, neuro-protection, and anti-cancer effects. However, the effect of NGR1 on migration, adhesion, spreading, and osteogenic differentiation of MSCs required for bone tissue engineering application has not been tested properly. In this study, we aimed to analyze the effect of NGR1 on the cellular activities of MSCs. Since human adipose-derived stromal cells (hASCs) are commonly used MSCs for bone tissue engineering, we used hASCs as a model of MSCs. The optimal concentration of 0.05 μg/mL NGR1 was biocompatible and promoted migration and osteogenic differentiation of hASCs. Pro-angiogenic factor VEGF expression was upregulated in NGR1-treated hASCs. NGR1 enhanced the adhesion and spreading of hASCs on the bio-inert glass surface. NGR1 robustly promoted hASCs adhesion and survival in 3D-printed TCP scaffold both in vitro and in vivo. NGR1 mitigated LPS-induced expression of inflammatory markers IL-1β, IL-6, and TNF-α in hASCs as well as inhibited the RANKL/OPG expression ratio. In conclusion, the biocompatible NGR1 promoted the migration, adhesion, spreading, osteogenic differentiation, and anti-inflammatory properties of hASCs.

Signaling pathway(s) of TNFR2 required for the immunoregulatory effect of CD4+Foxp3+ regulatory T cells

CD4⁺Foxp3⁺ regulatory T cells (Tregs), a subpopulation of CD4⁺ T cells, are engaged in maintaining the periphery tolerance and preventing autoimmunity. Recent studies showed that tumor necrosis factor receptor 2 (TNFR2) is preferentially expressed by Tregs and the expression of this receptor identifies the maximally suppressive Tregs. That is, TNFR2 is a liable phenotypic and functional surface marker of Tregs. Moreover, TNF activates and expands Tregs through TNFR2. However, it is very interesting which signaling pathway(s) of TNFR2 is required for the inhibitory effect of Tregs. Compelling evidence shows three TNFR2 signaling pathways in Tregs, including NF-κB, MAPK and PI3K-Akt pathways. Here, we summarize and discuss the latest progress in the studies on the downstream signaling pathways of TNF-TNFR2 for controlling Treg homeostasis, differentiation and proliferation.

Targeting TNFR2 in Cancer: All Roads Lead to Rome

TNF receptor 2 (TNFR2) has become one of the best potential immune checkpoints that might be targeted, mainly because of its vital role in tumor microenvironments (TMEs). Overexpression of TNFR2 in some tumor cells and essential function in immunosuppressive cells, especially regulatory T cells (Tregs), makes blocking TNFR2 an excellent strategy in cancer treatment; however, there is evidence showing that activating TNFR2 can also inhibit tumor progression in vivo. In this review, we will discuss drugs that block and activate TNFR2 under clinical trials or preclinical developments up till now. Meanwhile, we summarize and explore the possible mechanisms related to them.

Antagonistic Antibody Targeting TNFR2 Inhibits Regulatory T Cell Function to Promote Anti-Tumor Activity

Infiltration of regulatory T cells (Tregs) in the tumor microenvironment suppresses anti-tumor immune response, and promotes tumor progression. Tumor necrosis factor receptor-2 (TNFR2), which is highly expressed on Tregs, activates Tregs through nuclear factor kappa B (NF-κB) pathway. Moreover, TNFR2⁺ Tregs have been shown to be most suppressive among all Tregs populations in tumor. Due to the unique expression pattern and function of TNFR2 on Tregs, a TNFR2 blocking antibody is expected to compromise Tregs function, relieve Tregs-mediated immunosuppression, and hence to enhance anti-tumor immune response. AN3025 is an antagonistic anti-human TNFR2 (hTNFR2) antibody that is currently under preclinical development. This study investigates the immunomodulatory and anti-tumor activity of AN3025. AN3025 was generated through rabbit immunization with extracellular domain of human TNFR2 and subsequent humanization by complementarity-determining regions (CDRs) grafting. AN3025 binds to the extracellular domain of both human and cynomolgus with sub-nanomolar affinity and specificity, but not mouse or rat TNFR2. AN3025 inhibited tumor necrosis factor alpha (TNFα) induced cell death of hTNFR2-overexpressing Jurkat cells by competing with TNFα for binding to hTNFR2. In the Tregs/T effector co-culture assay, AN3025 increased T effector proliferation and enhanced interferon gamma (IFNγ) production. As a monotherapy, AN3025 significantly inhibited MC38 tumor growth in TNFR2 humanized mouse model. Subsequent flow cytometry (FACS) and immunohistochemistry (IHC) analysis revealed that administration of AN3025 led to decreased Tregs population, increased CD4⁺ and CD8⁺ T cell numbers in the tumor. The anti-tumor activity of AN3025 was dependent on the existence of CD4⁺ and CD8⁺ T cells, as depletion of CD4⁺ and CD8⁺ T cells abolished the anti-tumor activity of AN3025. In addition, AN3025 in combination with anti-PD-1 antibody demonstrated stronger in-vivo anti-tumor activity. The potent anti-tumor efficacy of AN3025, either as a monotherapy or in combination with anti-PD-1 antibody, supports its further clinical development for the treatment of various human tumors.

Mesenchymal Stem Cells Overexpressing ACE2 Favorably Ameliorate LPS-Induced Inflammatory Injury in Mammary Epithelial Cells

Mesenchymal stem cells (MSCs) are capable of homing injury sites to exert anti-inflammatory as well as anti-damage effects and can be used as a vehicle for gene therapy. Angiotensin-converting enzyme 2 (ACE2) plays an important role in numerous inflammatory diseases, but fewer studies have been reported in animal mastitis. We hypothesized that MSCs overexpressing ACE2 is more effective in ameliorating lipopolysaccharide (LPS)-induced inflammatory injury in mammary epithelial cells compared to MSCs alone. The results showed that MSC-ACE2 inhibited the LPS induction by upregulation of TNF-α, IL-Iβ, IL-6, and iNOS mRNA expression levels in EpH4-Ev cells compared with MSCs. Furthermore, results showed that both MSC and MSC-ACE2 were significantly activated IL-10/STAT3/SOCS3 signaling pathway as well as inhibited TLR4/NF-κB and MAPK signaling pathways, but MSC-ACE2 had more significant effects. Meanwhile, MSC-ACE2 promoted the expression of proliferation-associated proteins and inhibited the expression of the apoptosis-associated proteins in EpH4-Ev cells. In addition, MSC and MSC-ACE2 reversed the LPS-induced downregulation expression levels of the tight junction proteins in mammary epithelial cells, indicating that both MSC as well as MSC-ACE2 could promote blood-milk barrier repair, and MSC-ACE2 was more effective. These results suggested that MSCs overexpressing ACE2 were more anti-inflammatory as well as anti-injurious action into LPS-induced inflammatory injury in the EpH4-Ev cells. Thus, MSCs overexpressing ACE2 is expected to serve as a potential strategy for mastitis treatment.

Role of the Interaction of Tumor Necrosis Factor-α and Tumor Necrosis Factor Receptors 1 and 2 in Bone-Related Cells

Tumor necrosis factor-α (TNF-α) is a pleiotropic cytokine expressed by macrophages, monocytes, and T cells, and its expression is triggered by the immune system in response to pathogens and their products, such as endotoxins. TNF-α plays an important role in host defense by inducing inflammatory reactions such as phagocytes and cytocidal systems activation. TNF-α also plays an important role in bone metabolism and is associated with inflammatory bone diseases. TNF-α binds to two cell surface receptors, the 55kDa TNF receptor-1 (TNFR1) and the 75kDa TNF receptor-2 (TNFR2). Bone is in a constant state of turnover; it is continuously degraded and built via the process of bone remodeling, which results from the regulated balance between bone-resorbing osteoclasts, bone-forming osteoblasts, and the mechanosensory cell type osteocytes. Precise interactions between these cells maintain skeletal homeostasis. Studies have shown that TNF-α affects bone-related cells via TNFRs. Signaling through either receptor results in different outcomes in different cell types as well as in the same cell type. This review summarizes and discusses current research on the TNF-α and TNFR interaction and its role in bone-related cells.

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.

Immunoregulatory effects of dental mesenchymal stem cells on T and B lymphocyte responses in primary Sjögren's syndrome

Background: In this article, the authors investigate the modulatory effects of dental mesenchymal stem cells (MSCs) on lymphocyte responses in primary Sjögren's syndrome (pSS), which is an autoimmune disease resulting from keratoconjunctivitis sicca and xerostomia. Methods: Mononuclear cells isolated from pSS patients cultured with or without dental MSCs and analyzed for lymphocyte responses via flow cytometry. Results: Dental-follicle (DF)- and dental-pulp (DP)-MSCs downregulated CD4⁺ T lymphocyte proliferation by increasing Fas-ligand expression on T lymphocytes and FoxP3 expressing Tregs, and decreasing intracellular IFN-γ and IL-17 secretion in pSS patients. DF-MSCs decreased the plasma B cell ratio in the favor of naive B cell population in pSS patients' mononuclear cells. Conclusion: DF- and DP-MSCs can be the new cellular therapeutic candidates for the regulation of immune responses in pSS.

Research Progress on the Treatment of Premature Ovarian Failure Using Mesenchymal Stem Cells: A Literature Review

Premature ovarian failure (POF) has become one of the main causes of infertility in women of childbearing age and the incidence of POF is increasing year by year, seriously affecting the physical and mental health of patients and increasing the economic burden on families and society as a whole. The etiology and pathogenesis of POF are complex and not very clear at present. Currently, hormone replacement therapy is mainly used to improve the symptoms of low estrogen, but cannot fundamentally solve the fertility problem. In recent years, stem cell (SC) transplantation has become one of the research hotspots in the treatment of POF. The results from animal experiments bring hope for the recovery of ovarian function and fertility in patients with POF. In this article, we searched the published literature between 2000 and 2020 from the PubMed database (https://pubmed.ncbi.nlm.nih.gov), and summarized the preclinical research data and possible therapeutic mechanism of mesenchymal stem cells (MSCs) in the treatment of POF. Our aim is to provide useful information for understanding POF and reference for follow-up research and treatment of POF.

Dental mesenchymal stromal/stem cells in different microenvironments— implications in regenerative therapy

Current research data reveal microenvironment as a significant modifier of physical functions, pathologic changes, as well as the therapeutic effects of stem cells. When comparing regeneration potential of various stem cell types used for cytotherapy and tissue engineering, mesenchymal stem cells (MSCs) are currently the most attractive cell source for bone and tooth regeneration due to their differentiation and immunomodulatory potential and lack of ethical issues associated with their use. The microenvironment of donors and recipients selected in cytotherapy plays a crucial role in regenerative potential of transplanted MSCs, indicating interactions of cells with their microenvironment indispensable in MSC-mediated bone and dental regeneration. Since a variety of MSC populations have been procured from different parts of the tooth and tooth-supporting tissues, MSCs of dental origin and their achievements in capacity to reconstitute various dental tissues have gained attention of many research groups over the years. This review discusses recent advances in comparative analyses of dental MSC regeneration potential with regards to their tissue origin and specific microenvironmental conditions, giving additional insight into the current clinical application of these cells.

Targeting Programmed Cell Death to Improve Stem Cell Therapy: Implications for Treating Diabetes and Diabetes-Related Diseases

Stem cell therapies have shown promising therapeutic effects in restoring damaged tissue and promoting functional repair in a wide range of human diseases. Generations of insulin-producing cells and pancreatic progenitors from stem cells are potential therapeutic methods for treating diabetes and diabetes-related diseases. However, accumulated evidence has demonstrated that multiple types of programmed cell death (PCD) existed in stem cells post-transplantation and compromise their therapeutic efficiency, including apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis. Understanding the molecular mechanisms in PCD during stem cell transplantation and targeting cell death signaling pathways are vital to successful stem cell therapies. In this review, we highlight the research advances in PCD mechanisms that guide the development of multiple strategies to prevent the loss of stem cells and discuss promising implications for improving stem cell therapy in diabetes and diabetes-related diseases.

Priming strategies for controlling stem cell fate: Applications and challenges in dental tissue regeneration

Mesenchymal stromal cells (MSCs) have attracted intense interest in the field of dental tissue regeneration. Dental tissue is a popular source of MSCs because MSCs can be obtained with minimally invasive procedures. MSCs possess distinct inherent properties of self-renewal, immunomodulation, proangiogenic potential, and multilineage potency, as well as being readily available and easy to culture. However, major issues, including poor engraftment and low survival rates in vivo, remain to be resolved before large-scale application is feasible in clinical treatments. Thus, some recent investigations have sought ways to optimize MSC functions in vitro and in vivo. Currently, priming culture conditions, pretreatment with mechanical and physical stimuli, preconditioning with cytokines and growth factors, and genetic modification of MSCs are considered to be the main strategies; all of which could contribute to improving MSC efficacy in dental regenerative medicine. Research in this field has made tremendous progress and continues to gather interest and stimulate innovation. In this review, we summarize the priming approaches for enhancing the intrinsic biological properties of MSCs such as migration, antiapoptotic effect, proangiogenic potential, and regenerative properties. Challenges in current approaches associated with MSC modification and possible future solutions are also indicated. We aim to outline the present understanding of priming approaches to improve the therapeutic effects of MSCs on dental tissue regeneration.

The TNF-α/TNFR2 Pathway: Targeting a Brake to Release the Anti-tumor Immune Response

Newly discovered anti-cancer immunotherapies, such as immune checkpoint inhibitors and chimeric antigen receptor T cells, focus on spurring the anti-tumor effector T cell (Teff) response. Although such strategies have already demonstrated a sustained beneficial effect in certain malignancies, a substantial proportion of treated patients does not respond. CD4⁺FOXP3⁺ regulatory T cells (Tregs), a suppressive subset of T cells, can impair anti-tumor responses and reduce the efficacy of currently available immunotherapies. An alternative view that has emerged over the last decade proposes to tackle this immune brake by targeting the suppressive action of Tregs on the anti-tumoral response. It was recently demonstrated that the tumor necrosis factor alpha (TNF-α) tumor necrosis factor receptor 2 (TNFR2) is critical for the phenotypic stabilization and suppressive function of human and mouse Tregs. The broad non-specific effects of TNF-α infusion in patients initially led clinicians to abandon this signaling pathway as first-line therapy against neoplasms. Previously unrecognized, TNFR2 has emerged recently as a legitimate target for anti-cancer immune checkpoint therapy. Considering the accumulation of pre-clinical data on the role of TNFR2 and clinical reports of TNFR2⁺ Tregs and tumor cells in cancer patients, it is now clear that a TNFR2-centered approach could be a viable strategy, once again making the TNF-α pathway a promising anti-cancer target. Here, we review the role of the TNFR2 signaling pathway in tolerance and the equilibrium of T cell responses and its connections with oncogenesis. We analyze recent discoveries concerning the targeting of TNFR2 in cancer, as well as the advantages, limitations, and perspectives of such a strategy.

Generation and characterization of novel co-stimulatory anti-mouse TNFR2 antibodies

Tumor necrosis factor receptor 2 (TNFR2) has gained much research interest in recent years because of its potential pivotal role in autoimmune disease and cancer. However, its function in regulating different immune cells is not well understood. There is a need for well-characterized reagents to selectively modulate TNFR2 function, thereby enabling definition of TNFR2-dependent biology in human and mouse surrogate models. Here, we describe the generation, production, purification, and characterization of a panel of novel antibodies targeting mouse TNFR2. The antibodies display functional differences in binding affinity and potency to block TNFα. Furthermore, epitope binding showed that the anti-mTNFR2 antibodies target different domains on the TNFR2 protein, associated with varying capacity to enhance CD8⁺ T-cell activation and costimulation. Moreover, the anti-TNFR2 antibodies demonstrate binding to isolated splenic mouse Tregs ex vivo and activated CD8+ cells, reinforcing their potential use to establish TNFR2-dependent immune modulation in translational models of autoimmunity and cancer.

Harnessing the innate and adaptive immune system for tissue repair and regeneration: Considering more than macrophages

Tissue healing and regeneration is a complex, choreographed, spatiotemporal process involving a plethora of cell types, the activity of which is stringently regulated in order for effective tissue repair to ensue post injury. A number of globally prevalent conditions such as heart disease, organ failure, and severe musculoskeletal disorders require new therapeutic strategies to repair damaged or diseased tissue, particularly given an ageing population in which obesity, diabetes, and consequent tissue defects have reached epidemic proportions. This is further compounded by the lack of intrinsic healing and poor regenerative capacity of certain adult tissues. While vast progress has been made in the last decade regarding tissue regenerative strategies to direct self-healing, for example, through implantation of tissue engineered scaffolds, several challenges have hampered the clinical application of these technologies. Control of the immune response is growing as an attractive approach in regenerative medicine and it is becoming increasingly apparent that an in depth understanding of the interplay between cells of the immune system and tissue specific progenitor cells is of paramount importance. Furthermore, the integration of immunology and bioengineering promises to elevate the efficacy of biomaterial-based tissue repair and regeneration. In this review, we highlight the role played by individual immune cell subsets in tissue repair processes and describe new approaches that are being taken to direct appropriate healing outcomes via biomaterial mediated targeting of immune cell activity. STATEMENT OF SIGNIFICANCE: It is becoming increasingly apparent that controlling the immune response is as an attractive approach in regenerative medicine. Here, we propose that an in-depth understanding of immune system and tissue specific progenitor cell interactions may reveal mechanisms by which tissue healing and regeneration takes place, in addition to identifying novel therapeutic targets that could be used to enhance the tissue repair process. To date, most reviews have focused solely on macrophage subsets. This manuscript details the role of other innate and adaptive immune cells such as innate lymphoid cells (ILCs), natural killer (NK) cells and γδT cells (in addition to macrophages) in tissue healing. We also describe new approaches that are being taken to direct appropriate healing outcomes via biomaterial mediated cytokine and drug delivery.

The Immunomodulatory Effect of Triptolide on Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) are known to have immunosuppressive ability and have been used in clinical treatment of acute graft-versus-host disease, one of severe complications of the hematopoietic stem cell transplantation. However, MSCs are activated to suppress the immune system only after encountering an inflammatory stimulation. Thus, it will be ideal if MSCs are primed to be activated and ready to suppress the immune reaction before being administered. Triptolide (TPL) is a diterpene triepoxide purified from a Chinese herb-Tripterygium wilfordii Hook.f. It has been shown to possess anti-inflammatory and immunosuppressive properties in vitro. In this study, we aimed to use TPL to prime umbilical cord-derived MSCs (TPL-primed UC-MSCs) to enter a stronger immunosuppressive status. UC-MSCs were primed with TPL, which was washed out thoroughly, and the TPL-primed UC-MSCs were resuspended in fresh medium. Although TPL inhibited the proliferation of UC-MSCs, 0.01 μM TPL for 24 h was tolerable. The surface markers of TPL-primed UC-MSCs were identical to those of non-primed UC-MSCs. TPL-primed UC-MSCs exhibited stronger anti-proliferative effect for activated CD4+ and CD8+ T cells in the allogeneic mixed lymphocyte reaction assay than the non-primed UC-MSCs. TPL-primed UC-MSCs promoted the expression of IDO-1 in the presence of IFN-γ, but TPL alone was not sufficient. Furthermore, TPL-primed UC-MSCs showed increased expression of PD-L1. Conclusively, upregulation of IDO-1 in the presence of IFN-γ and induction of PD-L1 enhances the immunosuppressive potency of TPL-primed UC-MSCs on the proliferation of activated T cells. Thus, TPL- primed MSCs may provide a novel immunosuppressive cell therapy.

Differences and similarities between mesenchymal stem cell and endothelial progenitor cell immunoregulatory properties against T cells

Bone-marrow-derived mesenchymal stem cells and endothelial progenitor cells have some interesting biological properties that make them unique for cell therapy of degenerative and cardiovascular disorders. Although both cell populations have been already studied and used for their regenerative potentials, recently their special immunoregulatory features have brought much more attention. Mesenchymal stem cells and endothelial progenitor cells have both proangiogenic functions and have been shown to suppress the immune response, particularly T cell proliferation, activation, and cytokine production. This makes them suitable choices for allogeneic stem cell transplantation. Nevertheless, these two cells do not have equal immunoregulatory activities. Many elements including their extraction sources, age/passage, expression of different markers, secretion of bioactive mediators, and some others could change the efficiency of their immunosuppressive function. However, to our knowledge, no publication has yet compared mesenchymal stem cells and endothelial progenitor cells for their immunological interaction with T cells. This review aims to specifically compare the immunoregulatory effect of these two populations including their T cell suppression, deactivation, cytokine production, and regulatory T cells induction capacities. Moreover, it evaluates the implications of the tumor necrosis factor alpha-tumor necrosis factor receptor 2 axis as an emerging immune checkpoint signaling pathway controlling most of their immunological properties.

Comparative analysis of the immunomodulatory potential of caprine fetal adnexa derived mesenchymal stem cells

The caprine mesenchymal stem cells (MSCs) derived from fetal adnexa are highly proliferative. These cells possess tri-lineage differentiation potential and express MSC surface antigens and pluripotency markers with a wound-healing potential. This present study was conducted to compare the immunomodulatory potential of caprine MSCs derived from the fetal adnexa. Mid-gestation caprine uteri (2-3 months) were collected from the abattoir to isolate MSCs from amniotic fluid (cAF), amniotic sac (cAS), Wharton's jelly (cWJ) and cord blood (cCB), which were expanded and characterized at the 3^rd passage. These MSCs were then stimulated with inflammatory cytokines (IFN-γ and TNF-α) to assess the percentage of inhibition produced on peripheral blood mononuclear cells (PBMCs) proliferation. The percentage of inhibition on activated PBMCs proliferation produced by cWJ MSCs and cAS MSCs was significantly higher than cCB and cAF MSCs. The relative mRNA expression profile and immunofluorescent localization of different immunomodulatory cytokines and growth factors were conducted upon stimulation. The mRNA expression profile of a set of different cytokines and growth factors in each caprine fetal adnexa MSCs were modulated. Indoleamine 2, 3 dioxygenase appeared to be the major immunomodulator in cWJ, cAF, and cCB MSCs whereas inducible nitric oxide synthase in cAS MSCs. This study suggests that caprine MSCs derived from fetal adnexa display variable immunomodulatory potential, which appears to be modulated by different molecules among sources.

Roles of Dental Mesenchymal Stem Cells in the Management of Immature Necrotic Permanent Teeth

Dental caries and trauma always lead to pulp necrosis and subsequent root development arrest of young permanent teeth. The traditional treatment, apexification, with the absence of further root formation, results in abnormal root morphology and compromises long-term prognosis. Regeneration endodontics procedures (REPs) have been developed and considered as an alternative strategy for management of immature permanent teeth with pulpal necrosis, including cell-free and cell-based REPs. Cell-free REPs, including revascularization and cell homing with molecules recruiting endogenous mesenchymal stem cells (MSCs), have been widely applied in clinical treatment, showing optimistic periapical lesion healing and continued root development. However, the regenerated pulp-dentin complex is still absent in these cases. Dental MSCs, as one of the essentials of tissue engineering, are vital seed cells in regenerative medicine. Dental MSC-based REPs have presented promising potential with pulp-dentin regeneration in large animal studies and clinical trials via cell transplantation. In the present review, we summarize current understanding of the biological basis of clinical treatments for immature necrotic permanent teeth and the roles of dental MSCs during this process and update the progress of MSC-based REPs in the administration of immature necrotic permanent teeth.

TNFR2: Role in Cancer Immunology and Immunotherapy

Immune checkpoint inhibitors (ICIs), including anti-CTLA-4 (cytotoxic T lymphocyte antigen-4) and anti-PD-1/PD-L1 (programmed death-1/programmed death-ligand 1), represent a turning point in the cancer immunotherapy. However, only a minor fraction of patients could derive benefit from such therapy. Therefore, new strategies targeting additional immune regulatory mechanisms are urgently needed. CD4⁺Foxp3⁺ regulatory T cells (Tregs) represent a major cellular mechanism in cancer immune evasion. There is compelling evidence that tumor necrosis factor (TNF) receptor type II (TNFR2) plays a decisive role in the activation and expansion of Tregs and other types of immunosuppressive cells such as myeloid-derived suppressor cells (MDSCs). Furthermore, TNFR2 is also expressed by some tumor cells. Emerging experimental evidence indicates that TNFR2 may be a therapeutic target to enhance naturally occurring or immunotherapeutic-triggered anti-tumor immune responses. In this article, we discuss recent advances in the understanding of the mechanistic basis underlying the Treg-boosting effect of TNFR2. The role of TNFR2-expressing highly suppressive Tregs in tumor immune evasion and their possible contribution to the non-responsiveness to checkpoint treatment are analyzed. Moreover, the role of TNFR2 expression on tumor cells and the impact of TNFR2 signaling on other types of cells that shape the immunological landscape in the tumor microenvironment, such as MDSCs, MSCs, ECs, EPCs, CD8⁺ CTLs, and NK cells, are also discussed. The reports revealing the effect of TNFR2-targeting pharmacological agents in the experimental cancer immunotherapy are summarized. We also discuss the potential opportunities and challenges for TNFR2-targeting immunotherapy.

The Current Status of Mesenchymal Stromal Cells: Controversies, Unresolved Issues and Some Promising Solutions to Improve Their Therapeutic Efficacy

Mesenchymal stromal cells (MSCs) currently constitute the most frequently used cell type in advanced therapies with different purposes, most of which are related with inflammatory processes. Although the therapeutic efficacy of these cells has been clearly demonstrated in different disease animal models and in numerous human phase I/II clinical trials, only very few phase III trials using MSCs have demonstrated the expected potential therapeutic benefit. On the other hand, diverse controversial issues on the biology and clinical applications of MSCs, including their specific phenotype, the requirement of an inflammatory environment to induce immunosuppression, the relevance of the cell dose and their administration schedule, the cell delivery route (intravascular/systemic vs. local cell delivery), and the selected cell product (i.e., use of autologous vs. allogeneic MSCs, freshly cultured vs. frozen and thawed MSCs, MSCs vs. MSC-derived extracellular vesicles, etc.) persist. In the current review article, we have addressed these issues with special emphasis in the new approaches to improve the properties and functional capabilities of MSCs after distinct cell bioengineering strategies.

Post-decellularization techniques ameliorate cartilage decellularization process for tissue engineering applications

Due to the current lack of innovative and effective therapeutic approaches, tissue engineering (TE) has attracted much attention during the last decades providing new hopes for the treatment of several degenerative disorders. Tissue engineering is a complex procedure, which includes processes of decellularization and recellularization of biological tissues or functionalization of artificial scaffolds by active cells. In this review, we have first discussed those conventional steps, which have led to great advancements during the last several years. Moreover, we have paid special attention to the new methods of post-decellularization that can significantly ameliorate the efficiency of decellularized cartilage extracellular matrix (ECM) for the treatment of osteoarthritis (OA). We propose a series of post-decellularization procedures to overcome the current shortcomings such as low mechanical strength and poor bioactivity to improve decellularized ECM scaffold towards much more efficient and higher integration.