Glycogen synthase kinase 3β inhibition promotes human iTreg differentiation and suppressive function

Vitamin D Decreases Susceptibility of CD4+ T Cells to HIV Infection by Reducing AKT Phosphorylation and Glucose Uptake: A Bioinformatic and In Vitro Approach

Activated immune cells are highly susceptible to human immunodeficiency virus (HIV) infection. Vitamin D (VitD) induces antimicrobial responses and reduces cellular activation. We investigated VitD effects on HIV-1 replication, glucose uptake, and gene regulation using computational and in vitro approaches. CD4+ T cells from healthy male donors were treated with VitD and infected with HIV-1. After 72 h, p24 protein was measured to assess viral replication. VitD effects on anti- and pro-HIV genes were analyzed by a Boolean network model based on curated databases and the literature. CCR5 and CXCR4 coreceptor expression, AKT phosphorylation, and glucose uptake were evaluated by flow cytometry, and expression of some model-identified genes was quantified by qPCR. VitD reduced p24 by 53.2% (p = 0.0078). Boolean network modeling predicted that VitD upregulates antiviral, migration, and cell-differentiation related genes, while downregulating genes related to cellular activation, proliferation, glucose metabolism, and HIV replication, notably AKT1, CCNT1, SLC2A1, HIF1A, and PFKL. In vitro, VitD reduced AKT phosphorylation by 26.6% (p = 0.0156), transcription of CCNT1 by 22.7% (p = 0.0391), and glucose uptake by 22.8% (p = 0.0039) without affecting classic antiviral genes or coreceptor expression. These findings suggest an anti-HIV effect of VitD, mediated through AKT and glucose metabolism downmodulation, both involved in cell activation and HIV-1 replication.

Glycogen metabolism genes as a molecular signature for subtyping, prognostic prediction, and immunotherapy selection in clear cell renal cell carcinoma

Glycogen accumulation is a typical feature in clear cell renal cell carcinoma (ccRCC). It has been reported that glycogen metabolism-related genes can promote the progression of ccRCC, but its role in molecular typing, prognosis, immune infiltration, and immunotherapy response has rarely been reported. We applied an unsupervised clustering approach for molecular typing of ccRCC. The least absolute shrinkage and selection operator regression (LASSO) was used for prognostic model construction. The robustness of the model is evaluated by multicenter mutual verification. Weighted gene co-expression network analysis (WGCNA) was used to explore potential biological mechanisms. RT-qPCR was used to identify mRNA relative expression. We found ccRCC can be divided into two subtypes based on glycogen metabolism-related genes, and the prognosis of patients between the two subtypes is significantly different. Furthermore, we constructed a prognostic model for ccRCC patients based on glycogen metabolism-related genes using LASSO algorithm. We found that the model has a strong prognostic effect. Subsequently, we explored the underlying mechanisms through WGCNA and found that the model is associated with immune-related signaling pathways. Finally, we also found that this prognostic model can be used as a marker of response to immunotherapy in patients with advanced ccRCC. In conclusion, glycogen metabolism-related genes have critical value in molecular typing and prognosis evaluation of ccRCC.

Characterization of novel CD8+ regulatory T cells and their modulatory effects in murine model of inflammatory bowel disease

Dysregulation of mucosal immune system has been proposed to be critical in the pathogenesis of inflammatory bowel diseases (IBDs). Regulatory T cells (Tregs) play an important role in regulating immune responses. Tregs are involved in maintaining intestinal homeostasis and exerting suppressive function in colitis. Our previous studies showed that a novel forkhead box protein P3 (Foxp3) negative Tregs (Treg-of-B cells), induced by culturing naïve CD4+ T cells with B cells, could protect against colitis and downregulate T helper (Th) 1 and Th17 cell cytokines in T cell-mediated colitis. In the present study, we aimed to induce Treg-of-B cells in the CD8+ T-cell population and investigate their characteristics and immunomodulatory functions. Our results showed that CD8+ Treg-of-B cells expressed Treg-associated markers, including lymphocyte-activation gene-3 (LAG3), inducible co-stimulator (ICOS), programmed death-1 (PD-1), cytotoxic T-lymphocyte-associated protein-4 (CTLA-4), tumor necrosis factor receptor superfamily member-4 (TNFRSF4, OX40), and tumor necrosis factor receptor superfamily member-18 (TNFRSF18, GITR), but did not express Foxp3. CD8+ Treg-of-B cells produced higher concentration of inhibitory cytokine interleukin (IL)-10, and expressed higher levels of cytotoxic factor granzyme B and perforin after stimulation, compared to those of CD8+CD25- T cells. Moreover, CD8+ Treg-of-B cells suppressed T cell proliferation in vitro and alleviated colonic inflammation in chronic dextran sulfate sodium (DSS)-induced colitis. In conclusion, our study identified a novel subpopulation of CD8+ Tregs with suppressive effects through cell contact. These CD8+ Treg-of-B cells might have therapeutic potential for IBDs.

Rubiginosin B selectively inhibits Treg cell differentiation and enhances anti-tumor immune responses by targeting calcineurin-NFAT signaling pathway

BACKGROUND

The accumulation of CD4⁺Foxp3⁺ regulatory T cells (Tregs) in the tumor microenvironment (TME) dampens anti-tumor immune responses and promotes tumor progression. Therefore, the elimination of Tregs has become a strategy to enhance the efficacy of tumor immunotherapy, although it is still a daunting challenge. Rhododendron brachypodum (R. brachypodum) is a perennial shrub mainly distributed in Southwestern China, whereas the chemical constituents in this plant remain elusive.

PURPOSE

To identify small-molecule inhibitors of Tregs from R. brachypodum.

METHODS

Meroterpenoids in R. brachypodum were isolated by column chromatography under the guidance of LCMS analyses. The structures of isolates were identified by spectroscopic data and quantum calculations. The activities of compounds were first evaluated on CD4⁺ T cell differentiation by flow cytometry in Th1, Th2, Th17, and Treg polarizing conditions, and then on CT26 and MC38 murine colorectal carcinoma cells-allografted mice models. The mechanism of action was first investigated by determining Foxp3 degradation in Jurkat T cells transfected with pLVX-TetOne-Puro-Foxp3-tGFP, and then through analyses of Foxp3 expression on several pre-transcriptional signaling molecules.

RESULTS

Two new prenylated phenolic acids (1 and 2) and a chromane meroterpenoid, rubiginosin B (RGB, 3) were obtained from R. brachypodum. The structure of S-anthopogochromene C (1) was rectified according to the electronic circular dichroism (ECD) experiment, and rhodobrachypodic acid (2) was proposed as the precursor of RGB by photochemical transformation. In this investigation, we first found that RGB (3) selectively suppressed the de novo differentiation of TGFβ-induced CD4⁺Foxp3⁺ regulatory T cells (iTregs), overcome the immunosuppressive TME, and consequently inhibited the growth of tumor in mouse models. The mechanistic study revealed that RGB could target calcineurin, inhibited the nuclear factor of activated T cells (NFAT) dephosphorylation, and down-regulated Foxp3 expression. The hypothetical binding modes of RGB with calcineurin were predicted by molecular docking, and the interactions were mainly hydrophobic effects and hydrogen bonds.

CONCLUSION

These results suggest that RGB enhances anti-tumor immune responses by inhibiting Treg cell differentiation through calcineurin-NFAT signaling pathway, and therefore RGB or its analogs may be used as adjuvant agents meriting further investigation.

CD8+iTregs mediate the protective effect of rapamycin against graft versus host disease in a humanized murine model

CD8⁺Tregs are important immunoregulatory cells that participate in immunopathological processes in many diseases. Rapamycin (Rapa) is a macrolide immunosuppressant that inhibits the mammalian target of rapamycin (mTOR) and has been shown to improve CD4⁺-induced Tregs (iTregs) generation. This study aimed to evaluate the role of Rapa in the generation and function of CD8⁺iTregs. Human CD8 + CD25-CD45RA + T cells were divided into two groups, one with Rapa and the other without Rapa, and both groups were cultured under Treg-induced conditions. Rapa significantly improved Foxp3 expression and the suppressive function of CD8⁺iTregs in vitro. Further studies showed that Rapa suppressed inflammatory cytokine expression and enhanced anti-inflammatory cytokine expression. Under inflammatory conditions in vitro, Rapa-CD8 + iTregs sustained Foxp3 and anti-inflammatory cytokine expression. An in-depth study showed that Rapa regulated CpG demethylation in the Foxp3 region and STAT1 and STAT3 phosphorylation in CD8⁺iTregs. Finally, we compared the regulatory ability of Rapa and all-trans retinoic acid, another reagent that stimulates CD4⁺ iTreg generation in vitro, which showed that Rapa, but not all-trans retinoic acid, improved CD8⁺ iTreg induction and suppressed CD4⁺T cell expansion in vitro and protected against graft-versus-host disease in a humanized murine model in vivo. These results strongly suggest that CD8⁺iTregs initiated by Rapa may represent a new therapeutic strategy for inflammatory and autoimmune diseases.

Macrophage GSK3β-deficiency inhibits the progression of hepatocellular carcinoma and enhances the sensitivity of anti-PD1 immunotherapy

BACKGROUND

Glycogen synthase kinase 3β (GSK3β) was originally discovered to regulate glycogen synthesis and show a relationship to tumors. However, the biological functions of GSK3β in tumor-associated macrophages (TAMs) in cancers including hepatocellular carcinoma (HCC) remain unclear.

METHODS

The enrichment of GSK3β in tumor tissues was assessed by Gene Expression Omnibus (GEO) database. The in vitro and in vivo assays assisted in evaluating how GSK3β in TAMs affected HCC in terms of proliferation, invasion and migration. Immunofluorescence was used to assess GSK3β expression in TAMs in the anti-PD1 therapy non-responsive HCC group and the responsive group. Western blot and coimmunoprecipitation were performed to demonstrate the interaction between GSK3β and PD-L1. We carried out in vivo experiments in a C57BL/6 mouse model of HCC established through subcutaneous injection.

RESULTS

GEO single-cell RNA sequencing data suggested that GSK3β was highly enriched in TAMs of HCC. According to in vitro and in vivo experiments, reducing GSK3β in TAMs inhibits the cancer cell proliferation, invasion, and migration. The immunofluorescence and immunohistochemistry results confirmed that the GSK3β is significantly upregulated in TAMs of the anti-PD1 therapy non-responsive group in comparison with the responsive group. In vitro and in vivo experiments confirmed that reduced GSK3β in TAMs are capable of enhancing the sensitivity of anti-PD1 immunotherapy for HCC by decreasing PD-L1 ubiquitination. Mass spectrometry results suggested that high expression of CD14⁺GSK3β⁺ in the peripheral blood mononuclear cell (PBMC) can predict non-responsive to anti-PD1 treatment. Moreover, escitalopram is confirmed to act as GSK3β inhibitor that can increase the sensitivity of anti-PD1 immunotherapy for HCC.

CONCLUSIONS

This study revealed that macrophage GSK3β deficiency can inhibit the development of HCC by inhibiting the M2 phenotype and enhance the sensitivity of anti-PD1 immunotherapy for HCC by decreasing PD-L1 ubiquitination. The expression of CD14⁺GSK3β⁺ in PBMC can noninvasively predict anti-PD1 sensitivity in HCC patients, which provides novel strategies to predict anti-PD1 sensitivity, increase anti-PD1 therapeutic effect, and bring new hope for HCC patients.

Tregs in Autoimmunity: Insights Into Intrinsic Brake Mechanism Driving Pathogenesis and Immune Homeostasis

CD4⁺CD25^highFoxp3⁺ regulatory T-cells (Tregs) are functionally characterized for their ability to suppress the activation of multiple immune cell types and are indispensable for maintaining immune homeostasis and tolerance. Disruption of this intrinsic brake system assessed by loss of suppressive capacity, cell numbers, and Foxp3 expression, leads to uncontrolled immune responses and tissue damage. The conversion of Tregs to a pathogenic pro-inflammatory phenotype is widely observed in immune mediated diseases. However, the molecular mechanisms that underpin the control of Treg stability and suppressive capacity are incompletely understood. This review summarizes the concepts of T_reg cell stability and T_reg cell plasticity highlighting underlying mechanisms including translational and epigenetic regulators that may enable translation to new therapeutic strategies. Our enhanced understanding of molecular mechanism controlling Tregs will have important implications into immune homeostasis and therapeutic potential for the treatment of immune-mediated diseases.

Analysis of Related Risk Factors of Microvascular Invasion in Hepatocellular Carcinoma

Objective

To forecast the onset of microvascular invasion (MVI) in patients with hepatoma by evaluating the preoperative aspartate aminotransferase-to-platelet ratio index (APRI), alpha-fetoprotein (AFP), neutrophil-to-lymphocyte ratio (NLR), and other clinicopathological data.

Methods

In this study, we retrospectively analysed the clinical data of 62 patients who received radical surgery for hepa toma from 2019 to 2021. Patients were separated into the MVI-negative group and the MVI-positive group according to the postoperative pathological diagnosis. The relationships between MVI and NLR, APRI, AFP, tumor size, and other clinical data were assessed using the univariate analysis, receiver operating characteristic (ROC) curve, least absolute shrinkage and selection operator (LASSO) analysis, and logistic analysis.

Results

The ROC curve determined that the cutoff values of NLR, platelet-to-lymphocyte ratio (PLR), and APRI were 1.520, 98, and 0.275, respectively. The univariate analysis showed that the MVI-positive result was associated with five factors: tumor size (χ² = 10.620, p = 0.001), AFP (χ² = 10.524, p = 0.001), Edmondson grade (χ² = 20.736, p < 0.001), NLR (χ² = 8.744, p = 0.003), and APRI (χ² = 4.849, p = 0.028). The LASSO analysis indicated that the risk factors were the number of tumors, PLR, APRI, NLR, AFP, Edmondson grade, and tumor size. The multivariate logistic regression analysis showed that NLR ≥ 1.520 (OR 11.119, p = 0.006), APRI ≥ 0.275 (OR 12.515, p = 0.009), AFP ≥ 200 μg/mL (OR 7.823, p = 0.016), and tumor size > 3 cm (OR 7.689, p = 0.022) were independent risk factors for MVI in patients with hepatoma.

Conclusion

Preoperative NLR, APRI, AFP, and tumor size are reliable indicators for predicting the appearance of MVI in patients with hepatoma and are of great value in making detailed and reliable treatment protocols for these patients before surgery.

Inhibition of Glycogen Synthase Kinase 3β Increases the Proportion and Suppressive Function of CD19+CD24hiCD27+ Breg Cells

CD19⁺CD24^hiCD27⁺ memory Breg cells exhibit decreased abundance in patients with chronic graft-versus-host disease (cGVHD) after liver transplantation and produce less IL-10 than those from patients without cGVHD and healthy donors. Due to the lack of Breg cells and the difficulty in expanding them in vitro, in mouse models and early human clinical trials, the adoptive transfer of Breg cells to autoimmune diseases is greatly restricted. Glycogen synthase kinase 3β (GSK-3β) is a multifunctional serine/threonine (ser/thr) protein kinase that can participate in B cell growth, metabolic activity, and proliferation. Phosphoprotein array analysis showed that p-GSK-3β-s9 was highly expressed in mBreg cells. Furthermore, here, we demonstrated that GSK-3β expression in mBreg cells is lower than that observed in B cells by flow cytometry. We found that the treatment of B cells with the specific GSK-3β inhibitor SB216763 can significantly increase the proportion and immunosuppressive function of mBreg cells in vitro. Nuclear factor of activated T cells (NFAT) is one of a pivotal regulator of gene expression in adaptive immune system. Here, we observed that inhibition of GSK-3β by SB216763 results in enhanced expression of NFATc1 in B cells, which is essential in regulating the ability of B cells to secrete IL-10. By constructing a xGVHD mouse model, we observed that SB216763-treated mBreg cells effectively prevent xenogeneic GVHD. Here we propose a novel strategy using SB216763 to inhibit GSK-3β and then enhance the proportion and immunosuppressive function of mBreg cells by increasing the expression of NFATc1. This approach may be used as a therapy to ameliorate GVHD and inflammatory diseases.

Glycogen synthase kinase 3β in tumorigenesis and oncotherapy (Review)

Glycogen synthase kinase 3β (GSK 3β), a multifunctional serine and threonine kinase, plays a critical role in a variety of cellular activities, including signaling transduction, protein and glycogen metabolism, cell proliferation, cell differentiation, and apoptosis. Therefore, aberrant regulation of GSK 3β results in a broad range of human diseases, such as tumors, diabetes, inflammation and neurodegenerative diseases. Accumulating evidence has suggested that GSK 3β is correlated with tumorigenesis and progression. However, GSK 3β is controversial due to its bifacial roles of tumor suppression and activation. In addition, overexpression of GSK 3β is involved in tumor growth, whereas it contributes to the cell sensitivity to chemotherapy. However, the underlying regulatory mechanisms of GSK 3β in tumorigenesis remain obscure and require further in‑depth investigation. In this review, we comprehensively summarize the roles of GSK 3β in tumorigenesis and oncotherapy, and focus on its potentials as an available target in oncotherapy.

Cutting Edge: Inhibition of Glycogen Synthase Kinase 3 Activity Induces the Generation and Enhanced Suppressive Function of Human IL-10+ FOXP3+-Induced Regulatory T Cells

IL-10 is critical for Foxp3⁺ regulatory T cell (Tregs)-mediated immune suppression, but how to efficiently upregulate IL-10 production in Tregs remains unclear. In this article, we show that human IL-10⁺ FOXP3⁺-induced regulatory T cell (iTreg) generation can be dramatically promoted by inhibiting GSK3 activity. IL-10⁺ FOXP3⁺ iTregs induced by GSK3 inhibition exhibit classical features of immune-suppressive T cells. We further demonstrate that IL-10⁺ iTregs exhibit enhanced suppressive function in both IL-10-dependent and -independent manners. The enhanced suppressive function of IL-10⁺ Tregs is not due to a single factor such as IL-10, although IL-10 may mediate this enhanced suppressive function to some extent. Mechanistically, the increased transcriptional activity of IL-10 promoter and the enhanced expression of C-Maf and BLIMP1 coordinately facilitate IL-10 expression in human iTregs under GSK3 inhibition. Our study provides a new strategy to generate human immune-suppressive IL-10⁺ FOXP3⁺ Tregs for immunotherapies.

The Role of GSK-3 in Cancer Immunotherapy: GSK-3 Inhibitors as a New Frontier in Cancer Treatment

The serine/threonine kinase glycogen synthase kinase-3 (GSK-3) was initially identified because of its key role in the regulation of glycogen synthesis. However, it is now well-established that GSK-3 performs critical functions in many cellular processes, such as apoptosis, tumor growth, cell invasion, and metastasis. Aberrant GSK-3 activity has been associated with many human diseases, including cancer, highlighting its potential therapeutic relevance as a target for anticancer therapy. Recently, newly emerging data have demonstrated the pivotal role of GSK-3 in the anticancer immune response. In the last few years, many GSK-3 inhibitors have been developed, and some are currently being tested in clinical trials. This review will discuss preclinical and initial clinical results with GSK-3β inhibitors, highlighting the potential importance of this target in cancer immunotherapy. As described in this review, GSK-3 inhibitors have been shown to have antitumor activity in a wide range of human cancer cells, and they may also contribute to promoting a more efficacious immune response against tumor target cells, thus showing a double therapeutic advantage.

A Phenotypic Screening Approach Using Human Treg Cells Identified Regulators of Forkhead Box p3 Expression

Regulatory T (Treg) cells, expressing the transcription factor forkhead box p3 (FOXP3), are the key cells regulating peripheral autoreactive T lymphocytes by suppressing effector T cells. FOXP3⁺ Treg cells play essential roles controlling immune responses in autoimmune diseases and cancer. Several clinical approaches (e.g., polyclonal expansion of Treg cells with anti-CD3 and anti-CD28 coated beads in the presence of drugs) are under evaluation. However, expression of FOXP3, recognized as the master regulator of Treg cells, in induced Treg cells have been shown to be instable, and molecular targets involved in regulating FOXP3 expression and Treg cell function have not been well-defined. Thus, new targets directly regulating FOXP3 expression and the expression of its downstream genes (e.g., cytotoxic T-lymphocyte-associated protein 4 (CTLA4)) have the potential to stabilize the Treg cell phenotype and function. This report describes the development of an automated medium-throughput 384-well plate flow cytometry phenotypic assay meauring the protein expression of FOXP3 and CTLA4 in human Treg cells. Screening a library of 4213 structurally diverse compounds allowed us to identify a variety of compounds regulating FOXP3 and CTLA4 expression. Further evaluation of these and related small molecules, followed by confirmation using siRNA-mediated gene knockdown, revealed three targets: euchromatic histone-lysine N-methyltransferase (EHMT2) and glycogen synthase kinase 3 alpha/beta (GSK3α/β) as potent positive regulators of FOXP3 expression, and bromodomain and extra-terminal domain (BET) inhibitors as negative regulators of FOXP3 and CTLA4 expression. These targets have potential implications for establishing novel therapies for autoimmune diseases and cancer.

Gimap5-dependent inactivation of GSK3β is required for CD4+ T cell homeostasis and prevention of immune pathology

GTPase of immunity-associated protein 5 (Gimap5) is linked with lymphocyte survival, autoimmunity, and colitis, but its mechanisms of action are unclear. Here, we show that Gimap5 is essential for the inactivation of glycogen synthase kinase-3β (GSK3β) following T cell activation. In the absence of Gimap5, constitutive GSK3β activity constrains c-Myc induction and NFATc1 nuclear import, thereby limiting productive CD4⁺ T cell proliferation. Additionally, Gimap5 facilitates Ser389 phosphorylation and nuclear translocation of GSK3β, thereby limiting DNA damage in CD4⁺ T cells. Importantly, pharmacological inhibition and genetic targeting of GSK3β can override Gimap5 deficiency in CD4⁺ T cells and ameliorates immunopathology in mice. Finally, we show that a human patient with a GIMAP5 loss-of-function mutation has lymphopenia and impaired T cell proliferation in vitro that can be rescued with GSK3 inhibitors. Given that the expression of Gimap5 is lymphocyte-restricted, we propose that its control of GSK3β is an important checkpoint in lymphocyte proliferation.

Loss of function GIMAP5 mutation is associated with lymphopenia, but how it mediates T cell homeostasis is unclear. Here the authors study Gimap5^−/− mice and a patient with GIMAP5 deficiency to show how this GTPAse negatively regulates GSK3β activity to prevent DNA damage and cell death.

Modulation of CD8+ memory stem T cell activity and glycogen synthase kinase 3β inhibition enhances anti-tumoral immunity in gastric cancer

The potential contributions of CD8⁺ memory stem T cells to anti-tumor immunity and immunotherapy responses in gastric cancer has not been demonstrated. We found that CD8⁺ memory stem T cell frequencies were increased in the peripheral blood of gastric cancer patients compared to healthy donors and declined in frequency with disease progression. Despite minimal in vitro cytotoxic activity, the adoptive transfer of CD8⁺ memory stem T cells into Rag1^-/- tumor bearing mice enhanced tumor regression compared to CD8⁺ central or effector memory T cell counterparts. This effect was associated with an increase in splenic, draining lymph node and tumor infiltrating CD8⁺ T cell numbers and the development of an altered CD8⁺ T cell phenotype not seen during homeostasis. GSK-3β inhibition is known to promote memory stem T cell accumulation by arresting effector T cell differentiation in vivo. Surprisingly however, GSK-3β inhibition conversely increased the cytotoxic capacity of CD8⁺ memory stem T cells in vitro, and this was associated with the induction of effector T cell-associated effector proteins including FasL. Finally, FasL neutralization following GSK-3β inhibition directly attenuated the anti-tumoral capacity of CD8⁺ memory stem T cells both in vitro and in vivo. Altogether, our findings identify the therapeutic potential of modulating CD8⁺ memory stem T cells for improved anti-tumoral responses against gastric cancer.