TNF Receptor Type II as an Emerging Drug Target for the Treatment of Cancer, Autoimmune Diseases, and Graft-Versus-Host Disease: Current Perspectives and In Silico Search for Small Molecule Binders

Globospiramine from Voacanga globosa Exerts Robust Cytotoxic and Antiproliferative Activities on Cancer Cells by Inducing Caspase-Dependent Apoptosis in A549 Cells and Inhibiting MAPK14 (p38α): In Vitro and Computational Investigations

Bisindole alkaloids are a source of inspiration for the design and discovery of new-generation anticancer agents. In this study, we investigated the cytotoxic and antiproliferative activities of three spirobisindole alkaloids from the traditional anticancer Philippine medicinal plant Voacanga globosa, along with their mechanisms of action. Thus, the alkaloids globospiramine (1), deoxyvobtusine (2), and vobtusine lactone (3) showed in vitro cytotoxicity and antiproliferative activities against the tested cell lines (L929, KB3.1, A431, MCF-7, A549, PC-3, and SKOV-3) using MTT and CellTiter-Blue assays. Globospiramine (1) was also screened against a panel of breast cancer cell lines using the sulforhodamine B (SRB) assay and showed moderate cytotoxicity. It also promoted the activation of apoptotic effector caspases 3 and 7 using Caspase-Glo 3/7 and CellEvent-3/7 apoptosis assays. Increased expressions of cleaved caspase 3 and PARP in A549 cells treated with 1 were also observed. Apoptotic activity was also confirmed when globospiramine (1) failed to promote the rapid loss of membrane integrity according to the HeLa cell membrane permeability assay. Network pharmacology analysis, molecular docking, and molecular dynamics simulations identified MAPK14 (p38α), a pharmacological target leading to cancer cell apoptosis, as a putative target. Low toxicity risks and favorable drug-likeness were also predicted for 1. Overall, our study demonstrated the anticancer potentials and apoptotic mechanisms of globospiramine (1), validating the traditional medicinal use of Voacanga globosa.

TNFRSF1B Gene Variants in Clinicopathological Aspects and Prognosis of Patients with Cutaneous Melanoma

Regulatory T lymphocytes play a critical role in immune regulation and are involved in the aberrant cell elimination by facilitating tumor necrosis factor connection to the TNFR2 receptor, encoded by the TNFRSF1B polymorphic gene. We aimed to examine the effects of single nucleotide variants TNFRSF1B c.587T>G, c.*188A>G, c.*215C>T, and c.*922C>T on the clinicopathological characteristics and survival of cutaneous melanoma (CM) patients. Patients were genotyped using RT-PCR. TNFRSF1B levels were measured using qPCR. Luciferase reporter assay evaluated the interaction of miR-96 and miR-1271 with the 3'-UTR of TNFRSF1B. The c.587TT genotype was more common in patients younger than 54 years old than in older patients. Patients with c.*922CT or TT, c.587TG or GG + c.*922CT or TT genotypes, as well as those with the haplotype TATT, presented a higher risk of tumor progression and death due to the disease effects. Individuals with the c.*922TT genotype had a higher TNFRSF1B expression than those with the CC genotype. miR-1271 had less efficient binding with the 3'-UTR of the T allele when compared with the C allele of the SNV c.*922C>T. Our findings, for the first time, demonstrate that TNFRSF1B c.587T>G and c.*922C>T variants can serve as independent prognostic factors in CM patients.

Scutellarin enhances anti-tumor immune responses by reducing TNFR2-expressing CD4+Foxp3+ regulatory T cells

One characteristic of tumor-associated CD4⁺Foxp3⁺ regulatory T cells (Tregs) is the high expression of tumor necrosis factor receptor type II (TNFR2), a receptor that mediates the decisive effect of tumor necrosis factor (TNF) in the activation and expansion of Tregs. There is increasing evidence that inhibition of TNFR2 can enhance anti-tumor immune responses. Therefore, we screened Chinese herbal extracts for their capacity to block TNF-TNFR2 interaction. The results showed that the treatment with a Chinese herb extract could inhibit TNFR2-induced biological responses in vitro, including the proliferation of TNFR2⁺ Tregs. Our subsequent study led to the identification of flavonoid compound scutellarin was responsible for the activity. Our results showed that scutellarin is able to disrupt the interaction of TNF-TNFR2 and inhibited the phosphorylation of p38 MAPK, a down-stream signaling component of TNFR2. Importantly, in vivo scutellarin treatment markedly enhanced the efficacy of tumor immunotherapy with CpG oligodeoxynucleotide in mouse CT26 colon cancer model. This effect of scutellarin was associated with the reduction of the number of tumor-infiltrating TNFR2-expressing Tregs and increased tumor infiltration of interferon-γ-producing CD8⁺ T cells. Our result also suggests that scutellarin or its analogs may be used as an adjuvant to enhance the anti-tumor effect of immunotherapeutic agent by eliminating TNFR2⁺ Treg activity.

Targeting TNFR2: A Novel Breakthrough in the Treatment of Cancer

Tumor necrosis factor (TNF) receptor type II (TNFR2) is expressed in various tumor cells and some immune cells, such as regulatory T cells and myeloid-derived suppressing cells. TNFR2 contributes a lot to the tumor microenvironment. For example, it directly promotes the occurrence and growth of some tumor cells, activates immunosuppressive cells, and supports immune escape. Existing studies have proved the importance of TNFR2 in cancer treatment. Here, we reviewed the activation mechanism of TNFR2 and its role in signal transduction in the tumor microenvironment. We summarized the expression and function of TNFR2 within different immune cells and the potential opportunities and challenges of targeting TNFR2 in immunotherapy. Finally, the advantages and limitations of TNFR2 to treat tumor-related diseases are discussed, and the problems that may be encountered in the clinical development and application of targeted anti-TNFR2 agonists and inhibitors are analyzed.

Potential Therapeutic Targets of Rehmannia Formulations on Diabetic Nephropathy: A Comparative Network Pharmacology Analysis

Background: Previous retrospective cohorts showed that Rehmannia-6 (R-6, Liu-wei-di-huang-wan) formulations were associated with significant kidney function preservation and mortality reduction among chronic kidney disease patients with diabetes. This study aimed to investigate the potential mechanism of action of common R-6 variations in a clinical protocol for diabetic nephropathy (DN) from a system pharmacology approach.

Study Design and Methods: Disease-related genes were retrieved from GeneCards and OMIM by searching “Diabetic Nephropathy” and “Macroalbuminuria”. Variations of R-6 were identified from a published existing clinical practice guideline developed from expert consensus and pilot clinical service program. The chemical compound IDs of each herb were retrieved from TCM-Mesh and PubChem. Drug targets were subsequently revealed via PharmaMapper and UniProtKB. The disease gene interactions were assessed through STRING, and disease–drug protein–protein interaction network was integrated and visualized by Cytoscape. Clusters of disease–drug protein–protein interaction were constructed by Molecular Complex Detection (MCODE) extension. Functional annotation of clusters was analyzed by DAVID and KEGG pathway enrichment. Differences among variations of R-6 were compared. Binding was verified by molecular docking with AutoDock.

Results: Three hundred fifty-eight genes related to DN were identified, forming 11 clusters which corresponded to complement and coagulation cascades and signaling pathways of adipocytokine, TNF, HIF-1, and AMPK. Five variations of R-6 were analyzed. Common putative targets of the R-6 variations on DN included ACE, APOE, CCL2, CRP, EDN1, FN1, HGF, ICAM1, IL10, IL1B, IL6, INS, LEP, MMP9, PTGS2, SERPINE1, and TNF, which are related to regulation of nitric oxide biosynthesis, lipid storage, cellular response to lipopolysaccharide, inflammatory response, NF-kappa B transcription factor activity, smooth muscle cell proliferation, blood pressure, cellular response to interleukin-1, angiogenesis, cell proliferation, peptidyl-tyrosine phosphorylation, and protein kinase B signaling. TNF was identified as the seed for the most significant cluster of all R-6 variations. Targets specific to each formulation were identified. The key chemical compounds of R-6 have good binding ability to the putative protein targets.

Conclusion: The mechanism of action of R-6 on DN is mostly related to the TNF signaling pathway as a core mechanism, involving amelioration of angiogenesis, fibrosis, inflammation, disease susceptibility, and oxidative stress. The putative targets identified could be validated through clinical trials.

The role of TNFR2+ Tregs in COVID-19: An overview and a potential therapeutic strategy

COVID-19 is a multi-faceted disease ranging from asymptomatic to severely ill condition that primarily affects the lungs and could advance to other organs as well. It's causing factor, SARS-CoV-2 is recognized to develop robust cell-mediated immunity that responsible to either control or exaggerate the infection. As an important cell subset that control immune responses and are significantly dysregulated in COVID-19, Tregs is proposed to be considered for COVID-19 management. Among its hallmark, TNFR2 is recently recognized to play important role in the function and survival of Tregs. This review gathers available TNFR2 agonists to directly target Tregs as a potential approach to overcome immune dysregulation that affect the severity in COVID-19. Furthermore, this review performs a rigid body docking of TNF-TNFR2 interaction and such interaction with TNFR2 agonist to predict the optimal targeting approach.

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.

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.

TNFα and Immune Checkpoint Inhibition: Friend or Foe for Lung Cancer?

Tumor necrosis factor-alpha (TNFα) can bind two distinct receptors (TNFR1/2). The transmembrane form (tmTNFα) preferentially binds to TNFR2. Upon tmTNFα cleavage by the TNF-alpha-converting enzyme (TACE), its soluble (sTNFα) form is released with higher affinity for TNFR1. This assortment empowers TNFα with a plethora of opposing roles in the processes of tumor cell survival (and apoptosis) and anti-tumor immune stimulation (and suppression), in addition to angiogenesis and metastases. Its functions and biomarker potential to predict cancer progression and response to immunotherapy are reviewed here, with a focus on lung cancer. By mining existing sequencing data, we further demonstrate that the expression levels of TNF and TACE are significantly decreased in lung adenocarcinoma patients, while the TNFR1/TNFR2 balance are increased. We conclude that the biomarker potential of TNFα alone will most likely not provide conclusive findings, but that TACE could have a key role along with the delicate balance of sTNFα/tmTNFα as well as TNFR1/TNFR2, hence stressing the importance of more research into the potential of rationalized treatments that combine TNFα pathway modulators with immunotherapy for lung cancer patients.

Beneficial effects of minocycline on the ovary of polycystic ovary syndrome mouse model: Molecular docking analysis and evaluation of TNF-α, TNFR2, TLR-4 gene expression

Polycystic ovary syndrome (PCOS) is the most common cause of ovulatory infertility. Inflammation may be involved in the pathogenesis and development of PCOS. We investigated the anti-inflammatory effect of minocycline on TNF-α, TNFR2, and TLR4 expression levels and the key features of PCOS in a mouse model. Molecular docking was performed by Molecular Operating Environment software. PCOS was induced by estradiol valerate injection (EV) (2 mg/kg/day) in 40 mice. After 28 days, the mice were divided into five groups, including control, PCOS, minocycline control, minocycline PCOS model (50 mg/kg), and letrozole PCOS (0.5 mg/kg). The Levels of FSH, LH, E2, and testosterone were determined by ELISA. H&E staining was used for histological analysis in the ovarian tissues. Docking scores were -10.35, -10.57, and -12.45 kcal/mol for TNFα, TLR-4, and TNFR2, respectively. The expression levels of TNF-α, TNFR2, and TLR4 were detected by Real-Time PCR. PCOS models exhibited acyclicity, a significant increase in E2 levels (P < 0.01), and no difference in FSH, LH, and testosterone. The expression levels of TNF-α, TNFR2, and TLR-4 significantly increased in PCOS (2.70, 7.90, and 14.83-fold, respectively). EV treatment significantly increased graafian follicles (P < 0.001) and decreased corpus luteum (CL) (P < 0.01). Minocycline treatment in PCOS led to a significant decrease in E2 (P < 0.01) and graafian follicles (P < 0.001) and a significant increase in the CL numbers (P < 0.05). Our findings showed the positive effects of minocycline on estradiol level, CL and graafian follicles counts, suggesting that minocycline might inhibit these proteins and improve ovulation in our mouse model of PCOS.

Ahmad WMA, Ahmed Asif J, Khoo SP, Husein A, Ab-Ghani Z, Kassim NK. Biomarkers for Temporomandibular Disorders: Current Status and Future Directions

Numerous studies have been conducted in the previous years with an objective to determine the ideal biomarker or set of biomarkers in temporomandibular disorders (TMDs). It was recorded that tumour necrosis factor (TNF), interleukin 8 (IL-8), IL-6, and IL-1 were the most common biomarkers of TMDs. As of recently, although the research on TMDs biomarkers still aims to find more diagnostic agents, no recent study employs the biomarker as a targeting point of pharmacotherapy to suppress the inflammatory responses. This article represents an explicit review on the biomarkers of TMDs that have been discovered so far and provides possible future directions towards further research on these biomarkers. The potential implementation of the interactions of TNF with its receptor 2 (TNFR2) in the inflammatory process has been interpreted, and thus, this review presents a new hypothesis towards suppression of the inflammatory response using TNFR2-agonist. Subsequently, this hypothesis could be explored as a potential pain elimination approach in patients with TMDs.

Preferential Expansion of CD4+Foxp3+ Regulatory T Cells (Tregs) In Vitro by Tumor Necrosis Factor

CD4⁺Foxp3⁺ regulatory T cells (Tregs) are a distinct subset of CD4 T cells that play indispensable role in the maintenance of immune homeostasis and prevention of deleterious immune responses to self-antigens. Tumor necrosis factor (TNF) is a key cytokine in the autoimmune inflammatory responses. The effect of TNF on Treg activity was extensively studied in the past decade. We for the first time reported that TNF through TNFR2 preferentially activates and expands Tregs. Our discovery is increasingly supported by the research community; however, some controversial results were reported. The differential results are likely caused by different experimental condition. A standard experiment protocol can help researchers to obtain more consistent results. In this chapter, we detail methods used to examine in vitro effect of exogenous TNF on the proliferative expansion of Tregs in unfractionated mouse CD4⁺ T cells. The related technic issues are analyzed and discussed.

The inhibitor of autophagy SBI-0206965 aggravates atherosclerosis through decreasing myeloid-derived suppressor cells

Atherosclerosis (AS) is currently the leading cause of mortality worldwide, with the development of new strategies to prevent the formation and rupture of atherosclerotic plaques being a paramount area of research. Amounting evidence suggests autophagy has an important role in the pathogenesis of AS and may be a potential therapeutic target. In this study, the effect of SBI-0206965(6965), a novel inhibitor of autophagy, was tested on the development of AS in apolipoprotein E deficient (ApoE^−/−) mice. Systemic application of 6965 was found to aggravate AS, with increased plaque size and decreased plaque stability in comparison with the control. Of note, it was observed that 6965 decreased the proportion of myeloid-derived suppressor cells (MDSCs). Further investigation demonstrated MDSCs markedly alleviated AS in ApoE^−/− mice; while 6965 reduced the viability and promoted apoptosis of MDSCs in vitro. This is the first study describing an association between autophagy and MDSCs in AS models, providing a novel mechanism to potentially target in the management of this condition.

TNFR2-expressing CD4+Foxp3+ regulatory T cells in cancer immunology and immunotherapy

CD4⁺Foxp3⁺ regulatory T cells (Tregs) represent a major cellular mechanism in tumor immune evasion. Elimination of Treg activity has become a strategy to devise an effective tumor immunotherapy. We reported that TNF receptor type II (TNFR2), one of two receptors transducing TNF biological activity, is preferentially expressed by the most suppressive subset of Tregs. By interaction with TNFR2, TNF plays a decisive role in the activation, expansion and phenotype stability of Tregs. We also found that highly suppressive TNFR2-expressing Tregs appear to be tumor-associated Tregs. This finding has been supported by recent studies in mouse tumor models and in cancer patients. In this chapter, published data revealing the important role of TNFR2⁺ Tregs in tumor development and metastasis in different tumor types are reviewed and analyzed. The therapeutic potential of targeting TNF-TNFR2 interaction as means to eliminate Treg activity, and consequently to enhance anti-tumor immune responses, also is discussed.

Tumour necrosis factor signalling in health and disease

The master pro-inflammatory cytokine, tumour necrosis factor (TNF), has been shown to modulate multiple signalling pathways, with wide-ranging downstream effects. TNF plays a vital role in the typical immune response through the regulation of a number of pathways encompassing an immediate inflammatory reaction with significant innate immune involvement as well as cellular activation with subsequent proliferation and programmed cell death or necrosis. As might be expected with such a broad spectrum of cellular effects and complex signalling pathways, TNF has also been implicated in a number of disease states, such as rheumatoid arthritis, ankylosing spondylitis, and Crohn’s disease. Since the time of its discovery over 40 years ago, TNF ligand and its receptors, TNF receptor (TNFR) 1 and 2, have been categorised into two complementary superfamilies, namely TNF (TNFSF) and TNFR (TNFRSF), and 19 ligands and 29 receptors have been identified to date. There have been significant advances in our understanding of TNF signalling pathways in the last decade, and this short review aims to elucidate some of the most recent advances involving TNF signalling in health and disease.