Regulatory T-cell trafficking: from thymic development to tumor-induced immune suppression

Engineered Treg cells: The heir to the throne of immunotherapy

Recently, increased interest in the use of Tregs as adoptive cell therapy for the treatment of autoimmune diseases and transplant rejection had led to several advances in the field. However, Treg cell therapies, while constantly advancing, indiscriminately suppress the immune system without the permanent stabilization of certain diseases. Genetically modified Tregs hold great promise towards solving these problems, but, challenges in identifying the most potent Treg subtype, accompanied by the ambiguity involved in identifying the optimal Treg source, along with its expansion and engineering in a clinical-grade setting remain paramount. This review highlights the recent advances in methodologies for the development of genetically engineered Treg cell-based treatments for autoimmune, inflammatory diseases, and organ rejection. Additionally, it provides a systematized guide to all the recent progress in the field and informs the readers of the feasibility and safety of engineered adoptive Treg cell therapy, with the aim to provide a framework for researchers involved in the development of engineered Tregs.

Progress on the molecular mechanism of portal vein tumor thrombosis formation in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors, with poor prognosis and high mortality. Early-stage HCC has no obvious clinical symptoms, and most patients are already at an advanced stage when they are diagnosed. Portal vein tumor thrombus (PVTT) is the most common complication and a poor prognostic factor for HCC, which frequently leads to portal vein hypertension, ascites, gastrointestinal bleeding, and tumor metastasis. The formation of PVTT is related to the complex structure and hemodynamic changes of the portal vein and is closely related to changes at the cellular and molecular levels. The differentially-expressed genes (DEGs) between PVTT and primary tumor (PT) suggest that the two tissues may have different clonal origins. Epigenetic and proteomic analyses also suggest complex and diverse mechanisms for the formation of PVTT. In addition, the tumor microenvironment and energy metabolism pathways are interrelated in regulating the invasion and progression of PVTT. Aerobic glycolysis and the tumor immune microenvironment have been the focus of recent studies on PVTT. In this review, we summarize the mechanism of PVTT formation at the cellular and molecular levels to provide information to guide better prevention and treatment of PVTT in the clinic.

Forkhead box M1 recruits FoxP3+ Treg cells to induce immune escape in hilar cholangiocarcinoma

Objective

Hilar cholangiocarcinoma (HCCA) is a malignancy related to chronic biliary tract inflammation. Tumor immune escape is a necessary process of tumorigenesis. Forkhead box M1 (FoxM1) could affect the progression of various carcinomas. This study attempted to elaborate on the mechanism of FoxM1 in HCCA immune escape.

Methods

HCCA cell lines were collected to measure the expression of FoxM1 and FoxP3. CD8⁺ T cells were extracted to establish the co‐culture system with HCCA cells and Treg cells. pcDNA3.1‐FoxM1 or si‐FoxP3 was transfected into HCCA cells in the co‐culture system. HCCA cell viability, mobility, and invasiveness as well as levels of transforming growth factor (TGF)‐β and interleukin (IL)‐6 were evaluated. The binding relation between FoxM1 and FoxP3 promoter was verified. HCCA cells with pcDNA3.1‐FoxM1 were subcutaneously injected into mice to establish the xenograft mouse models.

Results

FoxM1 and FoxP3 were overexpressed in HCCA cells. The co‐culture of CD8⁺ T and HCCA cells inhibited HCCA cell activity and Treg cells limited CD8⁺ T killing. FoxM1 overexpression strengthened the inhibiting role of Treg cells in CD8⁺ T killing, upregulated TGF‐β and IL‐6 levels, and encouraged HCCA immune escape. FoxM1 bound to the FoxP3 promoter region to promote FoxP3 transcription. Silencing of FoxP3 neutralized the promoting role of FoxM1 overexpression in Treg cell immunosuppression and HCCA cell immune escape. FoxM1 aggravated tumor development, upregulated FoxP3 expression, increased Treg cells, and reduced CD8⁺ T cells.

Conclusion

FoxM1 bound to the FoxP3 promoter region to promote FoxP3 transcription and recruited FoxP3⁺ Treg cells, thereby inducing HCCA immune escape.

Non-coding RNAs in hepatocellular carcinoma: Insights into regulatory mechanisms, clinical significance, and therapeutic potential

Hepatocellular carcinoma (HCC) is a complex and heterogeneous malignancy with high incidence and poor prognosis. In addition, owing to the lack of diagnostic and prognostic markers, current multimodal treatment options fail to achieve satisfactory outcomes. Tumor immune microenvironment (TIME), angiogenesis, epithelial-mesenchymal transition (EMT), invasion, metastasis, metabolism, and drug resistance are important factors influencing tumor development and therapy. The intercellular communication of these important processes is mediated by a variety of bioactive molecules to regulate pathophysiological processes in recipient cells. Among these bioactive molecules, non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), account for a large part of the human transcriptome, and their dysregulation affects the progression of HCC. The purpose of this review is to evaluate the potential regulatory mechanisms of ncRNAs in HCC, summarize novel biomarkers from somatic fluids (plasma/serum/urine), and explore the potential of some small-molecule modulators as drugs. Thus, through this review, we aim to contribute to a deeper understanding of the regulatory mechanisms, early diagnosis, prognosis, and precise treatment of HCC.

Microenvironmental Features Driving Immune Evasion in Myelodysplastic Syndromes and Acute Myeloid Leukemia

Bone marrow, besides the known functions of hematopoiesis, is an active organ of the immune system, functioning as a sanctuary for several mature immune cells. Moreover, evidence suggests that hematopoietic stem cells (the bone marrow’s functional unit) are capable of directly sensing and responding to an array of exogenous stimuli. This chronic immune stimulation is harmful to normal hematopoietic stem cells, while essential for the propagation of myeloid diseases, which show a dysregulated immune microenvironment. The bone marrow microenvironment in myelodysplastic syndromes (MDS) is characterized by chronic inflammatory activity and immune dysfunction, that drive excessive cellular death and through immune evasion assist in cancer cell expansion. Acute myeloid leukemia (AML) is another example of immune response failure, with features that augment immune evasion and suppression. In this review, we will outline some of the functions of the bone marrow with immunological significance and describe the alterations in the immune landscape of MDS and AML that drive disease progression.

The Mechanism Underlying the ncRNA Dysregulation Pattern in Hepatocellular Carcinoma and Its Tumor Microenvironment

HCC is one of the most common malignant tumors and has an extremely poor prognosis. Accumulating studies have shown that noncoding RNA (ncRNA) plays an important role in hepatocellular carcinoma (HCC) development. However, the details of the related mechanisms remain unclear. The heterogeneity of the tumor microenvironment (TME) calls for ample research with deep molecular characterization, with the hope of developing novel biomarkers to improve prognosis, diagnosis and treatment. ncRNAs, particularly microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), have been found to be correlated with HCC neogenesis and progression. In this review, we summarized the aberrant epigenetic and genetic alterations caused by dysregulated ncRNAs and the functional mechanism of classical ncRNAs in the regulation of gene expression. In addition, we focused on the role of ncRNAs in the TME in the regulation of tumor cell proliferation, invasion, migration, immune cell infiltration and functional activation. This may provide a foundation for the development of promising potential prognostic/predictive biomarkers and novel therapies for HCC patients.

Multilevel mechanism of immune checkpoint inhibitor action in solid tumors: History, present issues and future development (Review)

Immunotherapy with checkpoint inhibitors (antibodies that target and block immune checkpoints in the tumor microenvironment) is included in the standard of care for patients with different types of malignancy, such as melanoma, renal cell and urothelial carcinoma, lung cancer etc. The introduction of this new immunotherapy has altered the view on potential targets for treatment of solid tumors from tumor cells themselves to their immune microenvironment; this has led to a reconsideration of the mechanisms of tumor-associated immunity. However, only a subset of patients benefit from immunotherapy and patient response is often unpredictable, even with known initial levels of prognostic markers; the biomarkers for favorable response are still being investigated. Mechanisms of immune checkpoint inhibitors efficiency, as well as the origins of treatment failure, require further investigation. From a clinical standpoint, discrepancies between the theoretical explanation of inhibitors of immune checkpoint actions at the cellular level and their deployment at a tissue/organ level impede the effective clinical implementation of novel immune therapy. The present review assessed existing experimental and clinical data on functional activity of inhibitors of immune checkpoints to provide a more comprehensive picture of their mechanisms of action on a cellular and higher levels of biological organization.

FOXP3/HAT1 Axis Controls Treg Infiltration in the Tumor Microenvironment by Inducing CCR4 Expression in Breast Cancer

Infiltrating T-regulatory cells in the tumor microenvironment is a key impediment to immunotherapy and is linked to a poor prognosis. We found that tumor-infiltrating Tregs express a higher expression of the chemokine receptor CCR4 than peripheral Tregs in breast cancer patients. CCL22 and CCL17 are released by tumor cells and tumor-associated macrophages, attracting CCR4+ Tregs to the tumor site. The Treg lineage-specific transcription factor FOXP3 changes the CCR4 promoter epigenetically in conjunction with HAT1 to provide a space for FOXP3 binding and activation of the CCR4 gene. To increase CCR4 expression in Tregs, the FOXP3/HAT1 axis is required for permissive (K23 and K27) or repressive (K14 and K18) acetylation of histone-3. In murine breast and melanoma tumor models, genetic ablation of FOXP3 reduced CCR4+ Treg infiltration and tumor size while also restoring anti-tumor immunity. Overexpression of FOXP3, on the other hand, increased CCR4+ Treg infiltration, resulting in a decreased anti-tumor immune response and tumor progression. These findings point to FOXP3 playing a new role in the tumor microenvironment as a transcriptional activator of CCR4 and a regulator of Treg infiltration.

Imatinib Mesylate Exerted Antitumor Effect by Promoting Infiltration of Effector T Cells in Tumor

Imatinib mesylate is a potent tyrosine kinase inhibitor that may induce immunological effects, such as inhibition of immune suppressive cells; but, how it modulates the immune system remains to be completely elucidated. In this study, we showed that cell proliferation of CT26 colon cancer and Lewis lung carcinoma (3LL) lung cancer cells was not inhibited by imatinib in vitro, although its administration significantly suppressed the growth of CT26, but not 3LL, subcutaneous tumors, and prolonged survival in CT26 tumor-bearing mice. Further, we examined the expression of immune cell-related molecules in the tumors to elucidate the differences in imatinib-mediated antitumor effects between CT26 and 3LL tumors. The nCounter assay showed that the expression of CD8 and CD8⁺ T cell-recruiting chemokine genes was significantly elevated in imatinib-treated CT26 tumors than that in control tumors; however, the gene expression remained unchanged in imatinib-treated or control 3LL tumors. Furthermore, frequency of interferon-γ⁺ (IFN-γ⁺) CD8⁺ T cells was increased in imatinib-treated CT26 tumors than control tumors, indicating induction of antitumor immunity by imatinib. The analysis indicates that imatinib promotes infiltration of effector T cells in tumors by upregulating expression of cytokines that recruit CD8⁺ T cells in the tumor microenvironment, which may lead to a strong antitumor effect.

Intratumoral stem-like CCR4+ regulatory T cells orchestrate the immunosuppressive microenvironment in HCC associated with hepatitis B

BACKGROUND & AIMS

Regulatory T cell (Treg) depletion increases antitumor immunity. However, severe autoimmunity can occur following systemic loss of Tregs, which could be avoided by selectively depleting intratumoral Tregs. Herein, we aimed to investigate the role of tumor-infiltrating CCR4⁺ Tregs in hepatocellular carcinoma (HCC) and to provide a potential target strategy for immunotherapy.

METHODS

CCR4⁺ Tregs were analyzed by flow cytometry in murine models and clinical samples. The function of tumor-infiltrating and induced CCR4⁺ Tregs was interrogated by genetic and epigenetic approaches. To block CCR4⁺ Treg chemotaxis, we developed an N-terminus recombinant protein of CCR4 (N-CCR4-Fc) as a neutralizing pseudo-receptor that effectively bound to its ligand CCL22. The efficacy of CCR4 antagonism as an immunotherapeutic agent was evaluated by tumor weights, growth kinetics and survival curves.

RESULTS

CCR4⁺ Tregs were the predominant type of Tregs recruited to hepatitis B-associated HCC (HBV⁺ HCC), correlating with sorafenib resistance and HBV load titers. Compared with CCR4^- Tregs, CCR4⁺ Tregs exhibited increased IL-10 and IL-35 expression, and enhanced functionality in suppressing CD8⁺ T cells. CCR4⁺ Tregs also displayed PD-1⁺TCF1⁺ stem-like properties. ATAC-seq data revealed substantial chromatin remodeling between tumor-infiltrating Tregs (TIL-Tregs) and induced Tregs, suggesting that long-term chromatin reprogramming accounted for the acquisition of enhanced immunosuppressive stem-like specificity by CCR4⁺ TIL-Tregs. Treatment with a CCR4 antagonist or N-CCR4-Fc blocked intratumoral Treg accumulation, overcame sorafenib resistance, and sensitized tumors to PD-1 checkpoint blockade.

CONCLUSIONS

Intratumoral stem-like CCR4⁺ Tregs orchestrated immunosuppressive resource cells in the tumor microenvironment. CCR4 could be targeted to enhance antitumor immunity by specifically blocking infiltration of Tregs into the tumor microenvironment and inhibiting maintenance of the TIL-Treg pool.

LAY SUMMARY

Targeting regulatory T cells is a promising approach in cancer immunotherapy; however, severe autoimmunity can occur following systemic regulatory T cell loss. This could be avoided by selectively depleting intratumoral regulatory T cells. Herein, targeting intratumoral stem-like CCR4⁺ regulatory T cells helped to overcome sorafenib resistance and sensitize tumors to immune checkpoint blockade in mouse models of liver cancer. This approach could have wide clinical applicability.

CCL5 production in lung cancer cells leads to an altered immune microenvironment and promotes tumor development

Current immunotherapies for lung cancer are only effective in a subset of patients. Identifying tumor-derived factors that facilitate immunosuppression offers the opportunity to develop novel strategies to supplement and improve current therapeutics. We sought to determine whether expression of driver oncogenes in lung cancer cells affects cytokine secretion, alters the local immune environment, and influences lung tumor progression. We demonstrate that oncogenic EGFR and KRAS mutations, which are early events in lung tumourigenesis, can drive cytokine and chemokine production by cancer cells. One of the most prominent changes was in CCL5, which was rapidly induced by KRAS^G12V or EGFR^L858R expression, through MAPK activation. Immunocompetent mice implanted with syngeneic KRAS-mutant lung cancer cells deficient in CCL5 have decreased regulatory T cells (T_regs), evidence of T cell exhaustion, and reduced lung tumor burden, indicating tumor-cell CCL5 production contributes to an immune suppressive environment in the lungs. Furthermore, high CCL5 expression correlates with poor prognosis, immunosuppressive regulatory T cells, and alteration to CD8 effector function in lung adenocarcinoma patients. Our data support targeting CCL5 or CCL5 receptors on immune suppressive cells to prevent formation of an immune suppressive tumor microenvironment that promotes lung cancer progression and immunotherapy insensitivity.

Key role of the CCR2-CCL2 axis in disease modification in a mouse model of tauopathy

BACKGROUND

For decades, dementia has been characterized by accumulation of waste in the brain and low-grade inflammation. Over the years, emerging studies highlighted the involvement of the immune system in neurodegenerative disease emergence and severity. Numerous studies in animal models of amyloidosis demonstrated the beneficial role of monocyte-derived macrophages in mitigating the disease, though less is known regarding tauopathy. Boosting the immune system in animal models of both amyloidosis and tauopathy, resulted in improved cognitive performance and in a reduction of pathological manifestations. However, a full understanding of the chain of events that is involved, starting from the activation of the immune system, and leading to disease mitigation, remained elusive. Here, we hypothesized that the brain-immune communication pathway that is needed to be activated to combat tauopathy involves monocyte mobilization via the C-C chemokine receptor 2 (CCR2)/CCL2 axis, and additional immune cells, such as CD4⁺ T cells, including FOXP3⁺ regulatory CD4⁺ T cells.

METHODS

We used DM-hTAU transgenic mice, a mouse model of tauopathy, and applied an approach that boosts the immune system, via blocking the inhibitory Programmed cell death protein-1 (PD-1)/PD-L1 pathway, a manipulation previously shown to alleviate disease symptoms and pathology. An anti-CCR2 monoclonal antibody (αCCR2), was used to block the CCR2 axis in a protocol that partially eliminates monocytes from the circulation at the time of anti-PD-L1 antibody (αPD-L1) injection, and for the critical period of their recruitment into the brain following treatment.

RESULTS

Performance of DM-hTAU mice in short-term and working memory tasks, revealed that the beneficial effect of αPD-L1, assessed 1 month after a single injection, was abrogated following blockade of CCR2. This was accompanied by the loss of the beneficial effect on disease pathology, assessed by measurement of cortical aggregated human tau load using Homogeneous Time Resolved Fluorescence-based immunoassay, and by evaluation of hippocampal neuronal survival. Using both multiparametric flow cytometry, and Cytometry by Time Of Flight, we further demonstrated the accumulation of FOXP3⁺ regulatory CD4⁺ T cells in the brain, 12 days following the treatment, which was absent subsequent to CCR2 blockade. In addition, measurement of hippocampal levels of the T-cell chemoattractant, C-X-C motif chemokine ligand 12 (Cxcl12), and of inflammatory cytokines, revealed that αPD-L1 treatment reduced their expression, while blocking CCR2 reversed this effect.

CONCLUSIONS

The CCR2/CCL2 axis is required to modify pathology using PD-L1 blockade in a mouse model of tauopathy. This modification involves, in addition to monocytes, the accumulation of FOXP3⁺ regulatory CD4⁺ T cells in the brain, and the T-cell chemoattractant, Cxcl12.

Platelet transfusion for cancer secondary thrombocytopenia: Platelet and cancer cell interaction

Chemoradiotherapy and autoimmune disorder often lead to secondary thrombocytopenia in cancer patients, and thus, platelet transfusion is needed to stop or prevent bleeding. However, the effect of platelet transfusion remains controversial for the lack of agreement on transfusion strategies. Before being transfused, platelets are stored in blood banks, and their activation is usually stimulated. Increasing evidence shows activated platelets may promote metastasis and the proliferation of cancer cells, while cancer cells also induce platelet activation. Such a vicious cycle of interaction between activated platelets and cancer cells is harmful for the prognosis of cancer patients, which results in an increased tumor recurrence rate and decreased five-year survival rate. Therefore, it is important to explore platelet transfusion strategies, summarize mechanisms of interaction between platelets and tumor cells, and carefully evaluate the pros and cons of platelet transfusion for better treatment and prognosis for patients with cancer with secondary thrombocytopenia.

Regulatory T Cells in the Tumor Microenvironment

Regulatory T cells (T_regs) are an immunosuppressive subpopulation of CD4⁺ T cells that are endowed with potent suppressive activity and function to limit immune activation and maintain homeostasis. These cells are identified by the hallmark transcription factor FOXP3 and the high-affinity interleukin-2 (IL-2) receptor chain CD25. T_regs can be recruited to and persist within the tumor microenvironment (TME), acting as a potent barrier to effective antitumor immunity. This chapter will discuss [i] the history and hallmarks of T_regs; [ii] the recruitment, development, and persistence of T_regs within the TME; [iii] T_reg function within TME; asnd [iv] the therapeutic targeting of T_regs in the clinic. This chapter will conclude with a discussion of likely trends and future directions.

Tumor-infiltrating T-regulatory cells adapt to altered metabolism to promote tumor-immune escape

Tumor mass and its microenvironment alter host immune system in various ways to promote tumor growth. One of the modifications is evasion of immune surveillance by augmenting the number of Tregs in tumor vicinity. Elevated levels of Tregs are seen in peripheral circulation and tumor tissue of cancer patients. Cancer cells release several chemokines to attract Tregs in tumor-site. Infiltration of Tregs has clinical significance because being immunosuppressive infiltrating Tregs suppress other immune cells making the tumor microenvironment favorable for tumor growth. On the other hand, infiltrating Tregs show metabolic alteration in tumor microenvironment which allows their selective survival over the others. Persistence of Tregs in the tumor microenvironment and subsequent immunosuppression makes Tregs a potential therapeutic obstacle and the reason behind the failure of immunotherapy. In this review, we emphasize the recent development in the metabolic adaptation of tumor-infiltrating Tregs and the therapeutic approaches to boost immunity against cancer.

Tumor-Infiltrating Regulatory T-cell Accumulation in the Tumor Microenvironment Is Mediated by IL33/ST2 Signaling

Regulatory T cells (Treg) are enriched in the tumor microenvironment (TME) and suppress antitumor immunity; however, the molecular mechanism underlying the accumulation of Tregs in the TME is poorly understood. In various tumor models, tumor-infiltrating Tregs were highly enriched in the TME and had significantly higher expression of immune checkpoint molecules. To characterize tumor-infiltrating Tregs, we performed bulk RNA sequencing (RNA-seq) and found that proliferation-related genes, immune suppression-related genes, and cytokine/chemokine receptor genes were upregulated in tumor-infiltrating Tregs compared with tumor-infiltrating CD4+Foxp3- conventional T cells or splenic Tregs from the same tumor-bearing mice. Single-cell RNA-seq and T-cell receptor sequencing also revealed active proliferation of tumor infiltrating Tregs by clonal expansion. One of these genes, ST2, an IL33 receptor, was identified as a potential factor driving Treg accumulation in the TME. Indeed, IL33-directed ST2 signaling induced the preferential proliferation of tumor-infiltrating Tregs and enhanced tumor progression, whereas genetic deletion of ST2 in Tregs limited their TME accumulation and delayed tumor growth. These data demonstrated the IL33/ST2 axis in Tregs as one of the critical pathways for the preferential accumulation of Tregs in the TME and suggests that the IL33/ST2 axis may be a potential therapeutic target for cancer immunotherapy.

Higher Frequency and Increased Expression of Molecules Associated with Suppression on T Regulatory Cells from Newborn Compared with Adult Nonhuman Primates

T regulatory cells (Tregs) play a critical role in controlling the immune response, often limiting pathogen-specific cells to curb immune-mediated damage. Studies in human infants have reported an increased representation of Tregs in these individuals. However, how these cells differ from those in adults at various sites and how they respond to activation signals is relatively unknown. In this study, we used a newborn nonhuman primate model to assess Treg populations present at multiple sites with regard to frequency and phenotype in comparison with those present in adult animals. We found that Foxp3⁺ cells were more highly represented in the T cell compartment of newborn nonhuman primates for all sites examined (i.e., the spleen, lung, and circulation). In the spleen and circulation, newborn-derived Tregs expressed significantly higher levels of Foxp3 and CD25 compared with adults, consistent with an effector phenotype. Strikingly, the phenotype of Tregs in the lungs of adult and infant animals was relatively similar, with both adult and newborn Tregs exhibiting a more uniform PD-1⁺CD39⁺ phenotype. Finally, in vitro, newborn Tregs exhibited an increased requirement for TCR engagement for survival. Further, these cells upregulated CD39 more robustly than their adult counterpart. Together, these data provide new insights into the quantity of Tregs in newborns, their activation state, and their potential to respond to activation signals.

Infiltration of T cells promotes the metastasis of ovarian cancer cells via the modulation of metastasis-related genes and PD-L1 expression

Due to its high ability to disseminate, ovarian cancer remains one of the largest threats to women's health, worldwide. Evidence showed that the immune cells infiltrating the tumor microenvironment are crucial in mediating metastasis. Therefore, it is necessary to understand which types of immune cells are involved in metastasis, and to determine the mechanisms by which they influence the process. By immunohistochemistry, we found that higher concentrations of intratumoral CD8⁺ T cells were found to be correlated with an advanced grade and stage of ovarian cancer. Additionally, the infiltration of stromal CD8⁺ T cells was also significantly higher in tissues with advanced stages and metastatic tumors. A positive correlation between the infiltration of FoxP3⁺ Treg cells and histological grade was also observed, regardless of location. PD-L1 expression in metastatic tumors was also higher than that in paired primary ovarian tumors. Transwell migration and invasion assays revealed the increased migration and invasion of ovarian cancer cell lines (A2780CP and ES2) and ascites-derived ovarian cancer cells following co-culturing with CD8⁺ T cells. Enhanced expression of MMP-9, uPA, VEGF, bFGF, IL-8, IL-10, and PD-L1 by cancer cells following co-culturing with CD8⁺ T cells were also detected by qPCR, ELISA or flow cytometry. In conclusion, our findings suggest that the infiltrated T cells could promote the development of ovarian cancer, and provide another mechanism of immune evasion mediated by T cells.

Deciphering and Reversing Immunosuppressive Cells in the Treatment of Hepatocellular Carcinoma

Use of immune checkpoint inhibitors (ICIs) in hepatocellular carcinoma (HCC) has been partially successful. However, most HCC patients do not respond to immunotherapy. HCC has been shown to induce several immune suppressor mechanisms in patients. These suppressor mechanisms include involvement of myeloid-derived suppressor cells, regulatory T-cells, functionally impaired dendritic cells (DCs), neutrophils, monocytes, and tumor associated macrophages. The accumulation of immunosuppressive cells may lead to an immunosuppressive tumor microenvironment as well as the dense fibrotic stroma which may contribute to immune tolerance. Our laboratory has been investigating different cellular mechanisms of immune suppression in HCC patients. In vitro as well as in vivo studies have demonstrated that abrogation of the suppressor cells enhances or unmasks tumor-specific antitumor immune responses. Two or three effective systemic therapies including ICIs and/or molecular targeted therapies and the addition of innovative combination therapies targeting immune suppressor cells may lead to increased immune recognition with a greater tumor response. We reviewed the literature for the latest research on immune suppressor cells in HCC, and here we provide a comprehensive summary of the recent studies in this field.

Cancer-associated fibroblasts promote cell growth by activating ERK5/PD-L1 signaling axis in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the most common diseases, accounting for about 10 % cancer-related deaths. Previous studies have found that caner-associated fibroblasts (CAFs) are closely related to the occurrence and metastasis of CRC, but the detailed mechanism is not precise.

METHODS

Tumor cells and fibroblasts were co-cultured with a transwell system. Cell Counting Kit-8 and colony formation assays were performed to test the ability of cell proliferation. The flow cytometry was used to detect cell apoptosis. Western Blot was performed to assess protein expression levels. Quantitative real-time PCR was performed to detect mRNA expression levels. ERK5-IN-1 was used to inhibit the autophosphorylation of ERK5.

RESULTS

CAFs promoted cell proliferation and inhibited cell apoptosis in CRC cells. CAFs promoted the phosphorylation of ERK5 and the expression of programmed death-ligand 1 (PD-L1). Activated ERK5 promotes cell proliferation and inhibited cell apoptosis in CRC cells. The expression levels of ERK5 correlated with the expression of PD-L1 in CRC cells. CAFs promote cell growth by activating the ERK5/PD-L1 signaling axis in colorectal cancer.

CONCLUSIONS

CAFs significantly promoted cell proliferation and inhibited cell apoptosis in CRC cells, which features are dependent on regulating the ERK5/PD-L1 signaling axis.

Expression of Foxp3 and interleukin-7 receptor and clinicopathological characteristics of patients with diffuse large B-cell lymphoma

The most specific biomarker on the surface of regulatory T cells (Tregs) is the forkhead/wingeded-helix protein 3 (Foxp3). In contrast, the expression of interleukin-7 receptor (IL-7R) is low or negative in Tregs. The present study aimed to investigate the expression of Foxp3 and IL-7R in diffuse large B-cell lymphoma (DLBCL), and to analyse the clinicopathological characteristics of patients with DLBCL and their association with overall survival (OS). Immunohistochemistry was performed to detect the expression of Foxp3 and IL-7R on routinely processed formalin-fixed and paraffin-embedded specimens. The χ² test was used to analyse the association between the expression of Foxp3 and IL-7R and the clinicopathological characteristics of patients with DLBCL. Survival curves were used to investigate the effect of Foxp3 and IL-7R on patient prognosis. The results demonstrated that high Foxp3 expression in tissue was associated with non- germinal centre B-cell (GCB)-type disease (P=0.012), International Prognostic Index score >0 (P=0.012), stage 3 or 4 tumour (P=0.045) and disease progression and stabilization period (P=0.032). In addition, IL-7R expression was associated with non-GCB-type disease (P=0.001) and extranodal lymphoma (P=0.008). Furthermore, expression of Foxp3 and IL-7R was not associated with OS (P=0.447 and P=0.201, respectively). Foxp3 and IL-7R expression in non-GCB-type lymphoma was significantly higher compared with that in GCB lymphoma. The expression of Foxp3 and IL-7R may therefore help the development of individualized treatment, prognostic prediction and therapy stratification.

Correlations between CD4+ FoxP3+ Treg and expression of FoxM1 and Ki-67 in gastric cancer patients

AIMS

In this study, we intended to analyze the clinical significance of CD4⁺ FoxP3⁺ Tregs in gastric cancer patients and investigate the relationship between the proportion of CD4⁺ FoxP3⁺ Tregs in the peripheral blood and the expression of FoxM1 and Ki-67 in gastric cancer tissues.

METHODS

Flow cytometry was used to measure the CD4⁺ FoxP3⁺ Tregs level in peripheral blood from 70 gastric cancer patients one day before gastrectomy and D2 lymph node dissection. Immunohistochemistry staining was used to detect the expression of FoxM1 and Ki-67 in gastric cancer tissues. Data on clinico-pathological features and correlation between Tregs and the expression of FoxM1 and Ki-67 were then analyzed.

RESULTS

The average proportion of CD4⁺ FoxP3⁺ Tregs in gastric cancer patients' peripheral blood before surgery was 10.12 ± 2.85%, which was significantly higher in patients with late AJCC stage (P = 0.029) or lymph node metastasis (P = 0.003) compared to patients at earlier AJCC stage or without lymph node metastasis. The levels of CD4⁺ FoxP3⁺ Treg cells was positively correlated with the protein expression of FoxM1 (P = 0.003) and Ki-67 (P = 0.001), respectively.

CONCLUSION

These results suggest the level of CD4⁺ FoxP3⁺ Treg cells in peripheral blood has clinical significance in gastric cancer patients. The overexpression of FoxM1 and Ki-67 may relate to immunosuppression in gastric cancer.

MicroRNAs Involved in Metastasis of Hepatocellular Carcinoma: Target Candidates, Functionality and Efficacy in Animal Models and Prognostic Relevance

Hepatocellular carcinoma (HCC) is responsible for the second-leading cancer-related death toll worldwide. Although sorafenib and levantinib as frontline therapy and regorafenib, cabazantinib and ramicurimab have now been approved for second-line therapy, the therapeutic benefit is in the range of only a few months with respect to prolongation of survival. Aggressiveness of HCC is mediated by metastasis. Intrahepatic metastases and distant metastasis to the lungs, lymph nodes, bones, omentum, adrenal gland and brain have been observed. Therefore, the identification of metastasis-related new targets and treatment modalities is of paramount importance. In this review, we focus on metastasis-related microRNAs (miRs) as therapeutic targets for HCC. We describe miRs which mediate or repress HCC metastasis in mouse xenograft models. We discuss 18 metastasis-promoting miRs and 35 metastasis-inhibiting miRs according to the criteria as outlined. Six of the metastasis-promoting miRs (miR-29a, -219-5p, -331-3p, 425-5p, -487a and -1247-3p) are associated with unfavourable clinical prognosis. Another set of six down-regulated miRs (miR-101, -129-3p, -137, -149, -503, and -630) correlate with a worse clinical prognosis. We discuss the corresponding metastasis-related targets as well as their potential as therapeutic modalities for treatment of HCC-related metastasis. A subset of up-regulated miRs -29a, -219-5p and -425-5p and down-regulated miRs -129-3p and -630 were evaluated in orthotopic metastasis-related models which are suitable to mimic HCC-related metastasis. Those miRNAs may represent prioritized targets emerging from our survey.

Synergistic combination of oncolytic virotherapy with CAR T-cell therapy

For patients with advanced hematological malignancies the therapeutic landscape has been transformed by the emergence of adoptive cell transfer utilizing autologous chimeric antigen receptor (CAR)-redirected T-cells. However, solid tumors have proved far more resistant to this approach. Here, we summarize the numerous challenges faced by CAR T-cells designed to target solid tumors, highlighting, in particular, issues related to impaired trafficking, expansion, and persistence. In parallel, we draw attention to exciting developments in the burgeoning field of oncolytic virotherapy and posit strategies for the synergistic combination of oncolytic viruses with CAR T-cells to improve outcomes for patients with advanced solid tumors.

Tumor progression mechanisms: Insights from the central immune regulation of tissue homeostasis

Knowledge of the mechanisms underlying the spread of cancer at the cellular and molecular levels is expanding rapidly. However, the central regulators governing the initiation and the rate of tumor growth remain poorly established. The fundamental principles of innate and adaptive immunity may explain how immune cells generate a specific response to tumor tissue. In the current review, the functional features of the immune system that contribute to the maintenance of normal tissue homeostasis, as well as their disruption in malignant transformations, were analyzed. Experimental and clinical studies previously demonstrated the involvement of regulatory T-cells in the process of tumor metastasis in a tissue-specific manner. An understanding of the cross talk between lymphoid and tumor cells may provide an insight into cancer evolution in terms of the mechanisms of T-cell competency formation. Elucidating the mechanisms of tumor progression via central immune regulation has implications for the development of novel therapeutic agents that target immune checkpoints.

Plasmodium infection inhibits the expansion and activation of MDSCs and Tregs in the tumor microenvironment in a murine Lewis lung cancer model

BACKGROUND

A major challenge in the development of effective cancer immunotherapy is the ability of tumors and their microenvironment to suppress immune cells through immunosuppressive cells such as myeloid -derived suppressor cells and regulatory T cells. We previously demonstrated that Plasmodium infection promotes innate and adaptive immunity against cancer in a murine Lewis lung cancer model but its effects on immunosuppressive cells in the tumor microenvironment are unknown.

METHODS

Whole Tumors and tumor-derived sorted cells from tumor-bearing mice treated with or without plasmodium infected red blood cells were harvested 17 days post tumor implantation and analyzed using QPCR, western blotting, flow cytometry, and functional assays. Differences between groups were analyzed for statistical significance using Student's t-test.

RESULTS

Here we found that Plasmodium infection significantly reduced the proportions of MDSCs and Tregs in the lung tumor tissues of the treated mice by downregulating their recruiting molecules and blocking cellular activation pathways. Importantly, CD8⁺ T cells isolated from the tumors of Plasmodium-treated mice exhibited significantly higher levels of granzyme B and perforin and remarkably lower levels of PD-1.

CONCLUSION

We reveal for the first time, the effects of Plasmodium infection on the expansion and activation of MDSCs and Tregs with a consequent elevation of CD8⁺T cell-mediated cytotoxicity within the tumor microenvironment and hold great promise for the development of effective immunotherapeutic strategies.

Prognostic impact of tumor-infiltrating CD276/Foxp3-positive lymphocytes and associated circulating cytokines in patients undergoing radical nephrectomy for localized renal cell carcinoma

Renal cell carcinoma (RCC) is an immunogenic tumor and pathological specimen generally contain large quantities of tumor-infiltrating lymphocytes (TILs). Numerous cell types and cytokines could affect the immune escape mechanism of tumor cells. The aim of the present study was to investigate the prognostic impact of TILs and the associated circulating cytokines on localized clear cell RCC following radical nephrectomy. A total of 87 patients who had undergone radical nephrectomy and were pathologically diagnosed with localized clear cell RCC were included. The present study evaluated the profile of TILs with immunohistochemical analysis of tumor specimens using a panel of antibodies [cluster of differentiation (CD)-4, CD8, CD80, CD86, CD276, and Forkhead box p3 (Foxp3)]. Counts of each TIL were compared with clinicopathological variables. Based on the results of immunohistochemical analyses, putative cytokines, including interleukin (IL)-6, IL-10, IL-17, interferon-γ, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β, were selected, and their levels in preoperative serum were measured by ELISA. The levels were compared with TIL counts in tumor specimens. High counts of the CD276⁺ and Foxp3⁺ TILs were identified as independent factors for poor prognosis for metastasis and local recurrence following radical nephrectomy (P=0.033 and 0.006, respectively). A high CD276⁺ TIL count was associated with preoperative serum levels of TNF-α and IFN-γ (P=0.027 and P=0.035, respectively), whereas a high count of Foxp3⁺ TILs was associated with preoperative serum levels of TGF-β (P=0.021). High levels of TNF-α and TGF-β were associated with recurrence-free survival (P=0.035 and P=0.031, respectively). Topical intra-tumoral immunoreaction and systemic immune status may be associated with patients with localized RCC. The topical induction of the CD276⁺ and Foxp3⁺ TILs was suggested to be associated with high levels of serum TNF-α and IFN-γ. Preoperative serum levels of TNF-α and TGF-β could be simple and non-invasive biomarkers for risk stratification before radical surgery.

The role of T helper 17 and regulatory T cells in tumor microenvironment

T helper 17 (Th17) cells were first described as a novel T helper cell lineage independent from Th1 and Th2 subsets. Th17 cells play vital roles in inflammation and tumor immunity. It causes the dissipation of antitumor immunity and contribution to the survival of tumor cells, worsening tumor growth and metastasis. Tumor-infiltrating Th17 cells were seen innumerous cancers in mice and humans. There has been an association between intratumoral Th17 cell infiltration and both good and bad prognoses. Besides the protumoral roles defined for IL-17 andTh17 cells, several reports have shown that Th17 cells also drive antitumoral immunity. Various mechanisms by which Th17 cells control tumor growth are as following: recruitment of several immune cells including DCs, CD4⁺ T cells, and CD8⁺ T cells within tumors, activation of CD8⁺ T cells, and probably plasticity toward Th1 phenotype, related to IFN-γ and TNF-α production. Regulatory T cells (Tregs) have been exhibited to infiltrate human tumors and are believed to restrict antitumor immunity. The effect of Treg cells has been more controversial. Whereas some studies have proposed that a high density of Treg cells within the tumor associated with a poor clinical prognosis, other studies have presented a positive clinical prognosis, underlining the importance of elucidating the clinical significance of Treg cells further. Treg and Th17 cells play both positive and negative roles in regulating antitumor immune responses. In spite of the presence of these cells, yet some tumors develop and grow. These T cells by themselves are not adequate to efficiently mount antitumor immune responses.

Activated human Foxp3+ regulatory T cells produce membrane-bound TNF

TNF is a multifunctional cytokine that is critical to host defense against pathogens but can also drive the pathophysiology of inflammatory diseases. Inhibition of TNF occasionally causes exacerbation of some autoimmune diseases, suggesting a role for TNF in the regulation of immune homeostasis. Here, we demonstrate that human peripheral blood CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs) express membrane-bound TNF, a potent activator of the type 2 TNF receptor. While the type 1 TNF receptor can cause cell death and is expressed ubiquitously, the type 2 receptor promotes cell growth and its expression is limited mainly to immune and endothelial cells. When autocrine TNF is blocked in an in vitro culture without IL-2, activated Tregs stop proliferating. These data indicate a novel role for TNF as a Treg-derived autocrine growth factor.

Tight correlation between FoxM1 and FoxP3+ Tregs in gastric cancer and their clinical significance

The aim of the present study was to investigate the expression of Forkhead box transcription M1 (FoxM1) and Forkhead box transcription P3 (FoxP3) in gastric cancer tissues in order to reveal any correlation between FoxM1, FoxP3 and clinicopathological parameters. Their clinical significance in gastric cancer was also investigated. Immunohistochemistry was used to detect the expression of FoxM1 and FoxP3 in gastric cancer and para-cancer tissues. The clinical significance of FoxM1 and FoxP3 in gastric cancer was explored, and the association between FoxM1 and FoxP3 was further analyzed. As a result, the overexpression of FoxM1 and FoxP3 was evident in gastric cancer (P < 0.001). FoxM1 overexpression was showed to be correlated with late AJCC stage (P = 0.025), while positive tumoral FoxP3 expression was associated with deeper invasion (P = 0.020), lymph node metastasis (P = 0.019) and later AJCC stage (P = 0.024). Overexpression of FoxM1 or FoxP3 was revealed to be negative prognostic factors for survival duration (P < 0.05), whereas only FoxM1 was shown to be independently associated with prognosisin gastric cancer after multivariate analysis (P = 0.020). A significant and positive correlation between FoxM1 and FoxP3 expressions was finally confirmed (P = 0.001). This significantly positive correlation between FoxM1 and FoxP3 prompts that FoxM1 may induce immune inhibition by recruiting FoxP3+ Tregs, leading to the progression of carcinogenesis, invasion and metastasis.

Targeting regulatory T cells for improving cancer therapy: Challenges and prospects

OBJECTIVE

Regulatory T cells (Tregs) play a central role in immune responses to infectious agents and tumors. Paradoxically, Tregs protect self-cells from the immune response as a part of peripheral tolerance and prevents autoimmune disorders, whereas during the process of carcinogenesis, they are exploited by tumor cells for protection against antitumor immune responses. Therefore, Tregs are often considered as a major obstacle in anticancer therapy. The objective of this review is to provide a current understanding on Tregs as a potential cellular target for achieving therapeutic gain and discuss various approaches that are implicated at preclinical and clinical scenario.

RECENT FINDINGS

Several approaches like immunotherapy and adjuvant chemotherapy, which reduce Tregs population, have been found to be useful in improving local tumor control. Our recent observations with the glycolytic inhibitor, 2-deoxy-D-glucose, established as an adjuvant in radiotherapy and chemotherapy of tumors also show that potential of 2-deoxy-D-glucose to improve local tumor control is linked with its ability to reduce the Tregs pool.

CONCLUSIONS

Several published studies and emerging evidences indicate that suppression of Treg numbers, infiltration into the tumors, and function can improve the cancer therapy by enhancing the antitumor immunity.

Xihuang pill promotes apoptosis of Treg cells in the tumor microenvironment in 4T1 mouse breast cancer by upregulating MEKK1/SEK1/JNK1/AP-1 pathway

OBJECTIVE

To determine the role of the MEKK1/SEK1/JNK1/AP-1 pathway in the action of Xihuang pill (XHP) in reducing regulatory T (Treg) cell numbers in the tumor microenvironment in a 4T1 mouse breast cancer model, and to clarify the anti-tumor mechanism of XHP in breast cancer.

METHODS

We established a mouse 4T1 breast cancer model. Model mice were administered XHP for 2 weeks, and tumor tissues were then removed, weighed, sliced, and homogenized. Treg cells in the tumor microenvironment were isolated by magnetic cell sorting and analyzed by immunohistochemistry and flow cytometry. Treg cell apoptosis was detected by TdT-mediated dUTP nick end labeling. mRNA expression levels of MEKK1, SEK1, JNK1, and AP-1 in Treg cells in the tumor microenvironment were detected by quantitative real-time PCR and their protein expression levels were detected by immunofluorescence staining and western blot.

RESULTS

Tumor weights were significantly lower in the XHP groups compared with the untreated control group. The overall number of Treg cells in the tumor microenvironment decreased while the number of apoptotic Treg cells increased with increasing doses of XHP. mRNA and protein expression levels of MEKK1, SEK1, JNK1, and AP-1 in Treg cells in the tumor microenvironment increased with increasing doses of XHP.

CONCLUSION

XHP might promote Treg cell apoptosis in the tumor microenvironment and further inhibit the tumor growth of 4T1 mouse breast cancer. The mechanism of XHP may be related to upregulation of gene and protein expression of MEKK1, SEK1, JNK1, and AP-1 in Treg cells in the tumor microenvironment.

Late duodenal metastasis from renal cell carcinoma with newly developed malignant lymphoma: A case report

Duodenal metastasis from renal cell carcinoma (RCC) is rare. The current case report presents a very rare case of late duodenal metastasis from RCC with newly developed malignant lymphoma (diffuse large B-cell lymphoma: DLBCL) at the same time. A 64-year-old man with systemic lymph nodes swelling who had undergone left nephrectomy for RCC 25 years previously, was admitted to the present hospital. Inguinal lymph node biopsy was performed, leading to a diagnosis of DLBCL. fluorine-18-fluorodeoxy-glucose (¹⁸F-FDG)-positron emission tomography (PET)/computed tomography (CT) revealed multiple lymph nodes, spleen, and ileocecal lesions. CT revealed an obvious hypervascular tumor involving the duodenum/pancreatic head. The tumor was false-negative on ¹⁸F-FDG-PET/CT. On esophagogastroduodenoscopy, the tumor was detected in the descending portion of the duodenum and was observed to be consistent with the submucosal tumor with a central ulcer, resembling those of ulcer-forming DLBCL. A biopsy was then performed carefully, and a clear cell RCC-derived metastatic cancer was diagnosed. Ileocolonoscopy revealed mucosal thickening of the terminal ileum, and led to a diagnosis of DLBCL infiltration with biopsy. To the best of the author's knowledge, this is the first case report of the coexistence of metastatic cancer from RCC and malignant lymphoma in the small intestine simultaneously. It was necessary to make a careful differential diagnosis in the imaging studies.

Regulatory T-Cell Dynamics in Cutaneous and Mucocutaneous Leishmaniasis due to Leishmania braziliensis

To evaluate the dynamics of regulatory T cells (Tregs) during tegumentary leishmaniasis, we assessed peripheral blood and biopsies from 54 patients. Patients with cutaneous leishmaniasis (CL) had a decreased proportion of Tregs in the peripheral blood, but the proportion was higher in the biopsies of lesions. During treatment of CL, circulating Tregs increased reaching normal proportions, whereas antigen-specific interferon-γ responses diminished. By contrast, circulating Tregs from mucosal leishmaniasis patients failed to normalize during treatment. C-C chemokine receptor type 5 was expressed on a large proportion of Tregs at the site of infection. These results demonstrate increased Tregs at the site of infection, possibly homing from the peripheral circulation.

Phenotypic and Functional Properties of Tumor-Infiltrating Regulatory T Cells

Regulatory T (Treg) cells maintain immune homeostasis by suppressing excessive immune responses. Treg cells induce tolerance against self- and foreign antigens, thus preventing autoimmunity, allergy, graft rejection, and fetus rejection during pregnancy. However, Treg cells also infiltrate into tumors and inhibit antitumor immune responses, thus inhibiting anticancer therapy. Depleting whole Treg cell populations in the body to enhance anticancer treatments will produce deleterious autoimmune diseases. Therefore, understanding the precise nature of tumor-infiltrating Treg cells is essential for effectively targeting Treg cells in tumors. This review summarizes recent results relating to Treg cells in the tumor microenvironment, with particular emphasis on their accumulation, phenotypic, and functional properties, and targeting to enhance the efficacy of anticancer treatment.

Molecular adjuvants that modulate regulatory T cell function in vaccination: A critical appraisal

Adjuvants are substances used to enhance the efficacy of vaccines. They influence the magnitude and alter the quality of the adaptive immune response to vaccine antigens by amplifying or modulating different signals involved in the innate immune response. The majority of known adjuvants have been empirically identified. The limited immunogenicity of new vaccine antigens and the need for safer vaccines have increased the importance of identifying single, well-defined adjuvants with known cellular and molecular mechanisms for rational vaccine design. Depletion or functional inhibition of CD4⁺CD25⁺FoxP3⁺ regulatory T cells (Tregs) by molecular adjuvants has become an emergent approach in this field. Different successful results have been obtained for specific vaccines, but there are still unresolved issues such as the risk of autoimmune disease induction, the involvement of cells other than Tregs and optimization for different conditions. This work provides a comprehensive analysis of current approaches to inhibit Tregs with molecular adjuvants for vaccine improvement, highlights the progress being made, and describes ongoing challenges.

Glucocorticoid hormone treatment enhances the cytokine production of regulatory T cells by upregulation of Foxp3 expression

OBJECTIVE

Despite the fact that glucocorticoids (GC) are important therapeutic tools, their effects on regulatory T cells (Treg) are not well defined. The aim of our work was to investigate how GCs influence in vivo the thymic (tTreg) and peripheral Treg (pTreg) differentiation, survival and cytokine production.

METHODS

Tregs were detected with flow cytometry in lymphatic organs of 4-6 weeks old BALB/c mice after repeated (2-4days), high-dose in vivo GC treatment using CD4/CD25 cell surface and Foxp3/IL-10/TGFβ/glucocorticoid receptor (GR) intracellular staining. Cytokine, Foxp3, and GR mRNA levels of sorted CD4⁺CD25^high T cells were analyzed using RT-PCR. Foxp3 and GR localization in Treg cells was investigated with confocal microscopy.

RESULTS

GC treatment of mice resulted in increased relative tTreg frequency in the thymus, which was due to decreased total thymocyte numbers with unchanged absolute tTreg cell count. In contrast the relative pTreg cell ratio in secondary lymphatic organs decreased or showed no changes after GC treatment, while the absolute number of pTregs decreased. Elevated intracellular IL-10⁺ and TGFβ⁺ tTreg and pTreg ratios were measured in GC-treated animals, accompanied with elevated Foxp3 mRNA expression. In addition, GC treatment caused increased TGFβ and IL-35 mRNA expression in CD4⁺CD25^high+ splenic and elevated IL-10 mRNA level in thymic tTregs. GR expression of thymic tTreg cells was lower than in pTregs. GC treatment caused an opposite change in GR levels, elevating GR in tTregs but decreasing it in pTregs. We observed a nuclear localization of GR in both tTregs and pTregs, which showed high colocalization (∼60%) with Foxp3 transcription factor. These data suggest an interaction of these two transcription factors with further increase due to GC treatment in splenic pTregs.

CONCLUSION

Our data show selective survival of tTregs and elevated production of immunosuppressive cytokines by Treg cells after GC treatment, which may contribute to the immunosuppressive effects of GCs.

Types of Immune-Inflammatory Responses as a Reflection of Cell-Cell Interactions under Conditions of Tissue Regeneration and Tumor Growth

Inflammatory infiltration of tumor stroma is an integral reflection of reactions that develop in response to any damage to tumor cells including immune responses to antigens or necrosis caused by vascular disorders. In this review, we use the term "immune-inflammatory response" (IIR) that allows us to give an integral assessment of the cellular composition of the tumor microenvironment. Two main types of IIRs are discussed: type 1 and 2 T-helper reactions (Th1 and Th2), as well as their inducers: immunosuppressive responses and reactions mediated by Th22 and Th17 lymphocytes and capable of modifying the main types of IIRs. Cellular and molecular manifestations of each IIR type are analyzed and their general characteristics and roles in tissue regeneration and tumor growth are presented. Since inflammatory responses in a tumor can also be initiated by innate immunity mechanisms, special attention is given to inflammation based on them. We emphasize that processes accompanying tissue regeneration are prototypes of processes underlying cancer progression, and these processes have the same cellular and molecular substrates. We focus on evidence that tumor progression is mainly contributed by processes specific for the second phase of "wound healing" that are based on the Th2-type IIR. We emphasize that the effect of various types of immune and stroma cells on tumor progression is determined by the ability of the cells and their cytokines to promote or prevent the development of Th1- or Th2-type of IIR. Finally, we supposed that the nonspecific influence on the tumor caused by the cytokine context of the Th1- or Th2-type microenvironment should play a decisive role for suppression or stimulation of tumor growth and metastasis.

Chemoattractant Signals and Adhesion Molecules Promoting Human Regulatory T Cell Recruitment to Porcine Endothelium

BACKGROUND

Human CD4+CD25+Foxp3+ T regulatory cells (huTreg) suppress CD4+ T cell-mediated antipig xenogeneic responses in vitro and might therefore be used to induce xenograft tolerance. The present study investigated the role of the adhesion molecules, their porcine ligands, and the chemoattractant factors that may promote the recruitment of huTreg to porcine aortic endothelial cells (PAEC) and their capacity to regulate antiporcine natural killer (NK) cell responses.

METHODS

Interactions between ex vivo expanded huTreg and PAEC were studied by static chemotaxis assays and flow-based adhesion and transmigration assays. In addition, the suppressive function of huTreg on human antiporcine NK cell responses was analyzed.

RESULTS

The TNFα-activated PAEC released factors that induce huTreg chemotaxis, partially inhibited by antihuman CXCR3 blocking antibodies. Coating of PAEC with human CCL17 significantly increased the transmigration of CCR4+ huTreg under physiological shear stress. Under static conditions, transendothelial Treg migration was inhibited by blocking integrin sub-units (CD18, CD49d) on huTreg, or their respective porcine ligands intercellular adhesion molecule 2 (CD102) and vascular cell adhesion molecule 1 (CD106). Finally, huTreg partially suppressed xenogeneic human NK cell adhesion, NK cytotoxicity and degranulation (CD107 expression) against PAEC; however, this inhibition was modest, and there was no significant change in the production of IFNγ.

CONCLUSIONS

Recruitment of huTreg to porcine endothelium depends on particular chemokine receptors (CXCR3, CCR4) and integrins (CD18 and CD49d) and was increased by CCL17 coating. These results will help to develop new strategies to enhance the recruitment of host huTreg to xenogeneic grafts to regulate cell-mediated xenograft rejection including NK cell responses.

Regulatory T Cells in the Tumor Microenvironment and Cancer Progression: Role and Therapeutic Targeting

Recent years have seen significant efforts in understanding and modulating the immune response in cancer. In this context, immunosuppressive cells, including regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs), have come under intense investigation for their proposed roles in suppressing tumor-specific immune responses and establishing an immunosuppressive tumor microenvironment, thus enabling tumor immune evasion. Additionally, recent evidence indicates that Tregs comprise diverse and heterogeneous subsets; phenotypically and functionally distinct subsets of tumor-infiltrating Tregs could contribute differently to cancer prognosis and clinical outcomes. Understanding Treg biology in the setting of cancer, and specifically the tumor microenvironment, is important for designing effective cancer therapies. In this review, we critically examine the role of Tregs in the tumor microenvironment and in cancer progression focusing on human studies. We also discuss the impact of current therapeutic modalities on Treg biology and the therapeutic opportunities for targeting Tregs to enhance anti-tumor immune responses and clinical benefits.

Autoimmunity and Inflammation in Myelodysplastic Syndromes

Autoimmune and inflammatory conditions (AICs) are encountered in up to 25% of patients with myelodysplastic syndromes (MDS). A wide range of AICs have been reported in association with MDS and can range from limited clinical manifestations to systemic diseases affecting multiple organs. Vasculitides, connective tissue diseases, and inflammatory arthritis are frequently reported in different studies; noninfectious fever and constitutional symptoms at presentation are common. Associations between AICs and specific MDS characteristics vary by study, but the available data suggest that AICs cluster more often in younger patients with higher-risk MDS. In general, AICs do not seem to confer worse survival, although certain AICs may be associated with adverse outcome (e.g. vasculitis) or progression of MDS (Sweet's syndrome). Nonetheless, these complications may have a significant impact on quality of life and affect the timing and type of MDS-directed therapy. The mainstay of management of these complications in the short term relies on immunosuppressive drugs. Increasing evidence suggests that hypomethylating agents may be effective in treating these complications and reduce steroid dependence. While the pathogenesis of AICs is incompletely understood, growing appreciation of cellular immune deregulation, cytokine hypersecretion, and the genetic heterogeneity underlying MDS may improve our understanding of common pathways linking MDS, inflammation, and autoimmunity.

B7-H3, B7-H4, Foxp3 and IL-2 expression in cervical cancer: Associations with patient outcome and clinical significance

The aim of this study was to determine the expression of B7-H3, B7-H4, Foxp3 and IL-2 in cervical cancer tissues, and evaluate the corresponding clinical significance. The expression of B7-H3, B7-H4, Foxp3 and IL-2 in 108 cervical cancer specimens was detected using immunohistochemistry, and their relationship with clinicopathologic parameters was determined. B7-H3, B7-H4 and Foxp3 had high levels of expression in cervical cancer cells (72.22, 80.56, and 91.56%, respectively). B7-H3 levels were only significantly associated with tumor size (P=0.013), while B7-H4, Foxp3 and IL-2 levels were significantly associated with International Federation of Gynecology and Obstetrics (FIGO) stage (P=0.023, 0.014 and 0.036, respectively) and tumor size (P=0.045, 0.010 and 0.021, respectively). Their expression levels were not correlated with age, histologic type, differentiation and lymph node metastasis (all P>0.05). Cox regression multivariate analysis confirmed that B7-H3 or B7-H4 overexpression was an independent prognostic factor. In addition, there were significant positive relationships between the expression of B7-H3 and B7-H4 with Foxp3 (P<0.001). In contrast, the expression of B7-H3 and B7-H4 was negatively correlated with IL-2 (P<0.05). B7-H3, B7-H4 and Foxp3 may be useful biomarkers in patients with cervical cancer for predicting treatment.

Effects of radiation on T regulatory cells in normal states and cancer: mechanisms and clinical implications

Radiation remains an important component of cancer treatment. In addition to inducing tumor cell death through direct cytotoxic effects, radiation can also promote the regression of tumor via augment of immune response. Regulatory T cells (Tregs) are a unique subpopulation of CD4 positive cells, which are characterized by expression of the forkhead box P3 (Foxp3) transcription factor and high levels of CD25. Mounting evidence has shown that Tregs are implicated in the development and progression of various types of cancer, which makes Tregs an important target in cancer therapeutics. Generally, lymphocytes are regarded as radiosensitive. However, Tregs have been demonstrated to be relatively resistant to radiotherapy, which is partly mediated by downregulation of pro-apoptotic proteins and upregulation of anti-apoptotic proteins. Moreover, radiotherapy can increase the production of Tregs and the recruitment of Tregs to local tumor microenvironment. Tregs can attenuate radiation-induced tumor death, which cause the resistance of tumor to radiotherapy. Recent experimental studies and clinical trails have demonstrated that the combination of radiation with medications that target Tregs is promising in the treatment of several types of neoplasms. In this review, we discussed the effect of radiation on Tregs in physiological states and cancer. Further, we presented an overview of therapies that target Tregs to enhance the efficacy of radiation in cancer therapeutics.