Prevalence of regulatory T cells is increased in peripheral blood and tumor microenvironment of patients with pancreas or breast adenocarcinoma

Clinical Significance of Composition Changes in T-cell Subpopulations After Chemotherapy in Patients With Gastric Cancer

BACKGROUND/AIM

New therapeutic agents and prognostic biomarkers for gastric cancer are needed. We analyzed the composition of peripheral blood T-cell subpopulations in response to chemotherapy in patients with gastric cancer.

PATIENTS AND METHODS

Peripheral blood samples were collected from patients diagnosed with gastric cancer before and after chemotherapy (FOLFOX; oxaliplatin, 5-fluorouracil, and leucovorin). Peripheral blood mononuclear cells were isolated. Patients were divided into responder (n=5) and non-responder groups (n=2) based on their chemotherapy outcomes.

RESULTS

Non-responders showed lower numbers of CD4+/total cells and CD8+/total cells after chemotherapy compared to the responder group, but the difference was not significant (p=0.905, p=0.095). Naïve T, central memory T, effector memory T and effector T-cell counts differed in both groups after chemotherapy.

CONCLUSION

Changes in peripheral T-cell subpopulations after chemotherapy were confirmed in patients with gastric cancer, which may be a prognostic predictor and development of therapeutic agents.

Synergistic Activation of Bovine CD4+ T Cells by Neutrophils and IL-12

CD4+ T cell activation requires inflammatory cytokines to provide a third signal (3SI), such as interleukin-12 (IL-12). We recently reported that bovine neutrophils can enhance the activation of bovine CD4+ T cells. To explore the interactions between neutrophils and third signal cytokines in bovine CD4+ T cell activation, naïve CD4+ T cells were isolated from cattle lymph nodes and stimulated for 3.5 days with anti-bovine CD3 (first signal; 1SI), anti-bovine CD28 (second signal; 2SI), and recombinant human IL-12 (3SI) in the presence or absence of neutrophils harvested from the same animals. Indeed, the strongest activation was achieved in the presence of all three signals, as demonstrated by CD25 upregulation, IFNγ production in CD4+ T cells, and secretion of IFNγ and IL-2 in cell supernatants. More importantly, 1SI plus neutrophils led to enhanced CD25 expression that was further increased by IL-12, suggesting synergistic action by IL-12 and neutrophils. Consistently, neutrophils significantly increased IFNγ production in 1SI plus IL-12-stimulated CD4+ T cells. Our data suggest the synergy of neutrophils and IL-12 as a novel regulator on bovine CD4+ T cell activation in addition to three signals. This knowledge could assist the development of immune interventions for the control of infectious diseases in cattle.

Systemic immunity in cancer

Immunotherapy has revolutionized cancer treatment, but efficacy remains limited in most clinical settings. Cancer is a systemic disease that induces many functional and compositional changes to the immune system as a whole. Immunity is regulated by interactions of diverse cell lineages across tissues. Therefore, an improved understanding of tumour immunology must assess the systemic immune landscape beyond the tumour microenvironment (TME). Importantly, the peripheral immune system is required to drive effective natural and therapeutically induced antitumour immune responses. In fact, emerging evidence suggests that immunotherapy drives new immune responses rather than the reinvigoration of pre-existing immune responses. However, new immune responses in individuals burdened with tumours are compromised even beyond the TME. Herein, we aim to comprehensively outline the current knowledge of systemic immunity in cancer.

The effect of high intraoperative blood loss on pancreatic fistula development after pancreatoduodenectomy: An international, multi-institutional propensity score matched analysis

BACKGROUND

The association between intraoperative estimated blood loss and outcomes after pancreatoduodenectomy has, thus far, been rarely explored.

METHODS

In total, 7,706 pancreatoduodenectomies performed at 18 international institutions composing the Pancreas Fistula Study Group were examined (2003-2020). High estimated blood loss (>700 mL) was defined as twice the median. Propensity score matching (1:1 exact-match) was employed to adjust for variables associated with high estimated blood loss and clinically relevant pancreatic fistula occurrence. The study was powered to detect a 33% clinically relevant pancreatic fistula increase in the high estimated blood loss group, with α = 0.05 and β = 0.2.

RESULTS

The propensity score model included 966 patients with high estimated blood loss and 966 patients with lower estimated blood loss; all covariate imbalantces were solved. Patients with high estimated blood loss patients experienced higher clinically relevant pancreatic fistula rates (19.4 vs 12.6%, odds ratio 1.66; P < .001), as well as higher severe complication rates (27.8 vs 15.6%), transfusions (50.1 vs 14.3%), reoperations (9.2 vs 4.0%), intensive care unit transfers (9.9 vs 4.8%) and 90-day mortality (4.7 vs 2.0%, all P < .001). High estimated blood loss was an independent predictor for clinically relevant pancreatic fistula (odds ratio 1.78, 95% confidence interval 1.37-2.32), as were prophylactic Octreotide administration (odds ratio 1.95, 95% confidence interval 1.46-2.61) and soft pancreatic texture (odds ratio 5.32, 95% confidence interval 3.74-5.57; all P < .001). Moreover, a second model including 1,126 pancreatoduodenectomies was derived including vascular resections as additional confounder (14.0% vascular resections performed in each group). On multivariable regression, high estimated blood loss was confirmed an independent predictor for clinically relevant pancreatic fistula reduction (odds ratio 1.80, 95% confidence interval 1.32-2.44; P < .001), whereas vascular resection was not (odds ratio 0.64, 95% confidence interval 0.34-1.88; P = .156).

CONCLUSION

This study better establishes the relationship between estimated blood loss and outcomes after pancreatoduodenectomy. Despite inherent contributions to blood loss, its minimization is an actionable opportunity for clinically relevant pancreatic fistula reduction and performance optimization in pancreatoduodenectomy. Accordingly, practical insights are offered to achieve this goal.

Regulatory T Cells in Angiogenesis

Regulatory T cells (Tregs) are crucial mediators of immune homeostasis. They regulate immune response by suppressing inflammation and promoting self-tolerance. In addition to their immunoregulatory role, a growing body of evidence highlights the dynamic role of Tregs in angiogenesis, the process of forming new blood vessels. Although angiogenesis is critically important for normal tissue regeneration, it is also a hallmark of pathological processes, including malignancy and chronic inflammation. Interestingly, the role of Tregs in angiogenesis has been shown to be highly tissue- and context-specific and as a result can yield either pro- or antiangiogenic effects. For these reasons, there is considerable interest in determining the molecular underpinnings of Treg-mediated modulation of angiogenesis in different disease states. The present review summarizes the role of Tregs in angiogenesis and mechanisms by which Tregs regulate angiogenesis and discusses how these mechanisms differ in homeostatic and pathological settings.

Development of Anti-Mouse CC Chemokine Receptor 8 Monoclonal Antibodies for Flow Cytometry

CC chemokine receptor 8 (CCR8) belongs to the class A of G protein-coupled receptor. It is highly expressed on Treg and T helper 2 (T_H2) cells recruited to the inflammation site and is implicated in allergy and asthma. Recently, CCR8+Treg cells have been suggested to be a master regulator in the immunosuppressive tumor microenvironment; therefore, developing sensitive monoclonal antibodies (mAbs) for CCR8 has been desired. This study established a specific and sensitive mAb for mouse CCR8 (mCCR8), which is useful for flow cytometry by using the Cell-Based Immunization and Screening (CBIS) method. The established anti-mCCR8 mAb, C₈Mab-2 (rat IgG_2b, kappa), reacted with mCCR8-overexpressed Chinese hamster ovary-K1 (CHO/mCCR8) cells and P388 (mouse lymphoid neoplasma) or J774-1 (mouse macrophage-like) cells, which express endogenous mCCR8 by flow cytometry. C₈Mab-2, which was established by the CBIS method, could be useful for elucidating the mCCR8-related biological response by flow cytometry.

Causes of Death After Colorectal Cancer Diagnosis: A Population-Based Study

Background: Non-cancer causes of death in patients with colorectal cancer (CRC) have not received much attention until now. The purpose of the current study is to investigate the non-cancer causes of death in patients with CRC at different periods of latency.

Methods: Eligible patients with CRC were included from the Surveillance, Epidemiology, and End Results (SEER) database, and standardized mortality ratios (SMRs) were calculated using the SEER*Stat software 8.3.8.

Results: A total of 475,771 patients with CRC were included, of whom 230,841 patients died during the follow-up period. Within 5 years, CRC was the leading cause of death. Over time, non-cancer causes of death account for an increasing proportion. When followed up for more than 10 years, non-cancer deaths accounted for 71.9% of all deaths worldwide. Cardiovascular diseases were the most common causes of non-cancer deaths, accounting for 15.4% of the total mortality. Patients had a significantly higher risk of death from septicemia within the first year after diagnosis compared with the general population (SMR, 3.39; 95% CI, 3.11–3.69). Within 5–10 years after CRC diagnosis, patients had a significantly higher risk of death from diabetes mellitus (SMR, 1.27; 95% CI, 1.19–1.36). During the course of more than 10 years, patients with CRC had a significantly higher risk of death from atherosclerosis (SMR 1.47; 95% CI, 1.11–1.9).

Conclusions: Although CRC has always been the leading cause of death in patients with CRC, non-cancer causes of death should not be ignored. For patients with cancer, we should not only focus on anti-tumor therapies but also pay attention to the occurrence of other risks to prevent and manage them in advance.

A Phase 2 Randomized Placebo-Controlled Adjuvant Trial of GI-4000, a Recombinant Yeast Expressing Mutated RAS Proteins in Patients with Resected Pancreas Cancer

Purpose: GI-4000, a series of recombinant yeast expressing four different mutated RAS proteins, was evaluated in subjects with resected ras-mutated pancreas cancer. Methods: Subjects (n = 176) received GI-4000 or placebo plus gemcitabine. Subjects' tumors were genotyped to identify which matched GI-4000 product to administer. Immune responses were measured by interferon-γ (IFNγ) ELISpot assay and by regulatory T cell (Treg) frequencies on treatment. Pretreatment plasma was retrospectively analyzed by matrix-assisted laser desorption/ionization-time-of-flight (MALDI-ToF) mass spectrometry for proteomic signatures predictive of GI-4000 responsiveness. Results: GI-4000 was well tolerated, with comparable safety findings between treatment groups. The GI-4000 group showed a similar pattern of median recurrence-free and overall survival (OS) compared with placebo. For the prospectively defined and stratified R1 resection subgroup, there was a trend in 1 year OS (72% vs. 56%), an improvement in OS (523.5 vs. 443.5 days [hazard ratio (HR) = 1.06 [confidence interval (CI): 0.53-2.13], p = 0.872), and increased frequency of immune responders (40% vs. 8%; p = 0.062) for GI-4000 versus placebo and a 159-day improvement in OS for R1 GI-4000 immune responders versus placebo (p = 0.810). For R0 resection subjects, no increases in IFNγ responses in GI-4000-treated subjects were observed. A higher frequency of R0/R1 subjects with a reduction in Tregs (CD4⁺/CD45RA⁺/Foxp3^low) was observed in GI-4000-treated subjects versus placebo (p = 0.033). A proteomic signature was identified that predicted response to GI-4000/gemcitabine regardless of resection status. Conclusion: These results justify continued investigation of GI-4000 in studies stratified for likely responders or in combination with immune check-point inhibitors or other immunomodulators, which may provide optimal reactivation of antitumor immunity. ClinicalTrials.gov Number: NCT00300950.

The characteristics of the immune cell profiles in peripheral blood in cholangiocarcinoma patients

BACKGROUND

Immune related cells are known to be closely related to the therapeutic effects and prognoses of cancer patients. In this study, we analyzed immune cell profiles (ICP) of cholangiocarcinoma patients (CCA).

METHODS

To measure the frequency of immune cells, peripheral blood mononuclear cells of 41 CCA and 10 healthy volunteers (HV) were analyzed by FACS.

RESULTS

There were significant differences between CCA and HV in ICP, and these differences were a consequence of tumor-bearing status, because many items in ICP before surgery were restored to levels in HV after surgery. Therefore, these changes were specifically attributable to cholangiocarcinoma, and we examined if they can function as biomarkers for therapeutic effects and prognoses. A shorter overall survival was associated with a lower frequency of helper T cells (HT) (p = 0.001), a higher frequency of effector regulatory T cells (eTregs) (p = 0.008), and a lower frequency of CD80 + eTregs (p = 0.024) in the best supportive care group, with a lower frequency of CD25 + naïve Tregs (nTregs) (p = 0.005) in the chemotherapy group, and with a lower frequency of OX40 + HT (p = 0.022), CD25 + CD8 + T cells (p = 0.017), and OX40 + CD8 + T cells (p = 0.032) in the surgery group. The recurrence factors were a higher frequency of CD4 + T cells (p = 0.009), CCR6 + nTregs (p = 0.014), and CXCR3 + nTregs (p = 0.012), and a lower frequency of PD-1 + HT (p = 0.006), OX40 + HT (p = 0.004), CD8 + T cells (p = 0.001), and CTLA-4 + CD8 + T cells (p = 0.036).

CONCLUSIONS

The ICP in CCA are specifically attributable to cholangiocarcinoma, and may be biomarkers for therapeutic effects and prognoses.

Profiles of immune cell infiltration in head and neck squamous carcinoma

Tumor immune infiltration cells (TIICs) are highly heterogeneous, not only in different cancer subtypes but also within different cancer regions. We conducted the Cell-type Identification using Estimating Relative Subsets Of RNA Transcripts (CIBERSORT) method. We assessed the relative proportions of 22 TIICs in HNSC using publicly available TCGA transcriptional datasets, analyzed the proportions of TIICs between HNSC tissues and normal tissues, along with accompanying clinicopathological data, and the impact of TIICs on clinical outcome. After the filter criteria, a total of 395 patients were included in the analysis. We found significant differences in naïve B cells, monocytes, resting mast cells, activated mast cells, CD8⁺ T cells, and M0 macrophages between HNSC tissues and adjacent non-cancer tissues. We also found that some TIIC subgroups were significantly associated with clinical parameters. Moreover, the patients with low Tregs fraction had worse OS and DFS than those with high Tregs fraction. However, low M0 macrophages fraction was associated with better OS and DFS in HNSC patients. Moreover, Tregs and M0 macrophages are likely to be important determinants of prognosis, which may serve as a potential immunotherapy target for HNSC. Then, we screened the immune-related differentially expressed genes (DEGs), performed the GO and KEGG enrichment analysis, constructed the protein–protein interaction network, and screened the prognosis-related hub genes in HNSC. However, further clinical investigation and basic experiments are needed to validate our results, and uncover the molecular mechanisms interlinking TIICs in HNSC and their roles in prognosis and therapy.

Single-Cell Deconvolution of Head and Neck Squamous Cell Carcinoma

Complexities in cell-type composition have rightfully led to skepticism and caution in the interpretation of bulk transcriptomic analyses. Recent studies have shown that deconvolution algorithms can be utilized to computationally estimate cell-type proportions from the gene expression data of bulk blood samples, but their performance when applied to tumor tissues, including those from head and neck, remains poorly characterized. Here, we use single-cell data (~6000 single cells) collected from 21 head and neck squamous cell carcinoma (HNSCC) samples to generate cell-type-specific gene expression signatures. We leverage bulk RNA-seq data from >500 HNSCC samples profiled by The Cancer Genome Atlas (TCGA), and using single-cell data as a reference, apply two newly developed deconvolution algorithms (CIBERSORTx and MuSiC) to the bulk transcriptome data to quantitatively estimate cell-type proportions for each tumor in TCGA. We show that these two algorithms produce similar estimates of constituent/major cell-type proportions and that a high T-cell fraction correlates with improved survival. By further characterizing T-cell subpopulations, we identify that regulatory T-cells (Tregs) were the major contributor to this improved survival. Lastly, we assessed gene expression, specifically in the Treg population, and found that TNFRSF4 (Tumor Necrosis Factor Receptor Superfamily Member 4) was differentially expressed in the core Treg subpopulation. Moreover, higher TNFRSF4 expression was associated with greater survival, suggesting that TNFRSF4 could play a key role in mechanisms underlying the contribution of Treg in HNSCC outcomes.

Accumulation of long-chain fatty acids in the tumor microenvironment drives dysfunction in intrapancreatic CD8+ T cells

CD8⁺ T cells are master effectors of antitumor immunity, and their presence at tumor sites correlates with favorable outcomes. However, metabolic constraints imposed by the tumor microenvironment (TME) can dampen their ability to control tumor progression. We describe lipid accumulation in the TME areas of pancreatic ductal adenocarcinoma (PDA) populated by CD8⁺ T cells infiltrating both murine and human tumors. In this lipid-rich but otherwise nutrient-poor TME, access to using lipid metabolism becomes particularly valuable for sustaining cell functions. Here, we found that intrapancreatic CD8⁺ T cells progressively accumulate specific long-chain fatty acids (LCFAs), which, rather than provide a fuel source, impair their mitochondrial function and trigger major transcriptional reprogramming of pathways involved in lipid metabolism, with the subsequent reduction of fatty acid catabolism. In particular, intrapancreatic CD8⁺ T cells specifically exhibit down-regulation of the very-long-chain acyl-CoA dehydrogenase (VLCAD) enzyme, which exacerbates accumulation of LCFAs and very-long-chain fatty acids (VLCFAs) that mediate lipotoxicity. Metabolic reprogramming of tumor-specific T cells through enforced expression of ACADVL enabled enhanced intratumoral T cell survival and persistence in an engineered mouse model of PDA, overcoming one of the major hurdles to immunotherapy for PDA.

Common clonal origin of conventional T cells and induced regulatory T cells in breast cancer patients

Regulatory CD4+ T cells (Treg) prevent tumor clearance by conventional T cells (Tconv) comprising a major obstacle of cancer immune-surveillance. Hitherto, the mechanisms of Treg repertoire formation in human cancers remain largely unclear. Here, we analyze Treg clonal origin in breast cancer patients using T-Cell Receptor and single-cell transcriptome sequencing. While Treg in peripheral blood and breast tumors are clonally distinct, Tconv clones, including tumor-antigen reactive effectors (Teff), are detected in both compartments. Tumor-infiltrating CD4+ cells accumulate into distinct transcriptome clusters, including early activated Tconv, uncommitted Teff, Th1 Teff, suppressive Treg and pro-tumorigenic Treg. Trajectory analysis suggests early activated Tconv differentiation either into Th1 Teff or into suppressive and pro-tumorigenic Treg. Importantly, Tconv, activated Tconv and Treg share highly-expanded clones contributing up to 65% of intratumoral Treg. Here we show that Treg in human breast cancer may considerably stem from antigen-experienced Tconv converting into secondary induced Treg through intratumoral activation.

Searching for Peptide Inhibitors of T Regulatory Cell Activity by Targeting Specific Domains of FOXP3 Transcription Factor

(1) Background: The ability of cancer cells to evade the immune system is due in part to their capacity to induce and recruit T regulatory cells (Tregs) to the tumor microenvironment. Strategies proposed to improve antitumor immunity by depleting Tregs generally lack specificity and raise the possibility of autoimmunity. Therefore, we propose to control Tregs by their functional inactivation rather than depletion. Tregs are characterized by the expression of the Forkhead box protein 3 (FOXP3) transcription factor, which is considered their “master regulator”. Its interaction with DNA is assisted primarily by its interaction with other proteins in the so-called “Foxp3 interactome”, which elicits much of the characteristic Treg cell transcriptional signature. We speculated that the disruption of such a protein complex by using synthetic peptides able to bind Foxp3 might have an impact on the functionality of Treg cells and thus have a therapeutic potential in cancer treatment. (2) Methods: By using a phage-displayed peptide library, or short synthetic peptides encompassing Foxp3 fragments, or by studying the crystal structure of the Foxp3:NFAT complex, we have identified a series of peptides that are able to bind Foxp3 and inhibit Treg activity. (3) Results: We identified some peptides encompassing fragments of the leuzin zipper or the C terminal domain of Foxp3 with the capacity to inhibit Treg activity in vitro. The acetylation/amidation of linear peptides, head-to-tail cyclization, the incorporation of non-natural aminoacids, or the incorporation of cell-penetrating peptide motifs increased in some cases the Foxp3 binding capacity and Treg inhibitory activity of the identified peptides. Some of them have shown antitumoral activity in vivo. (4) Conclusions: Synthetic peptides constitute an alternative to inhibit Foxp3 protein–protein interactions intracellularly and impair Treg immunosuppressive activity. These peptides might be considered as potential hit compounds on the design of new immunotherapeutic approaches against cancer.

Metabolic reprogramming of T regulatory cells in the hypoxic tumor microenvironment

Metabolic dysregulation in the hypoxic tumor microenvironment (TME) is considered as a hallmark of solid tumors, leading to changes in biosynthetic pathways favoring onset, survival and proliferation of malignant cells. Within the TME, hypoxic milieu favors metabolic reprogramming of tumor cells, which subsequently affects biological properties of tumor-infiltrating immune cells. T regulatory cells (Tregs), including both circulating and tissue-resident cells, are particularly susceptible to hypoxic metabolic signaling that can reprogram their biological and physicochemical properties. Furthermore, metabolic reprogramming modifies Tregs to utilize alternative substrates and undergo a plethora of metabolic events to meet their energy demands. Major impact of this metabolic reprogramming can result in differentiation, survival, excessive secretion of immunosuppressive cytokines and proliferation of Tregs within the TME, which in turn dampen anti-tumor immune responses. Studies on fine-tuning of Treg metabolism are challenging due to heterogenicity of tissue-resident Tregs and their dynamic functions. In this review, we highlight tumor intrinsic and extrinsic factors, which can influence Treg metabolism in the hypoxic TME. Moreover, we focus on metabolic reprogramming of Tregs that could unveil potential regulatory networks favoring tumorigenesis/progression, and provide novel insights, including inhibitors against acetyl-coA carboxylase 1 and transforming growth factor beta into targeting Treg metabolism for therapeutic benefits.

CD30+OX40+ Treg is associated with improved overall survival in colorectal cancer

Regulatory T cells (Tregs) are often enriched in tumors, where their immunosuppressive function has a key role in tumor persistence and progression. In colorectal cancer (CRC), however, Tregs are frequently associated with an improved clinical outcome. Tumor-infiltrating Tregs have been shown to exhibit a distinct signature comprising the co-stimulatory molecules (OX40, 4-1BB), cytokine receptors (IL1R2, IL21R, CCR8, CD30), and co-inhibitory molecules (PD-L1, TIGIT). Here, we showed by flow cytometry that circulating CD45RO⁺ Tregs from patients with CRC (n = 25) have elevated CD30 and OX40 expression compared to healthy subjects (n = 14). We identified co-expression of CD30 and OX40 on circulating CD45RO⁺ Tregs using single-cell images captured by the DEPArray^™ system. The frequency of CD30⁺OX40⁺CD45RO⁺ Tregs was significantly higher in CRC patients than in healthy subjects (P < 0.001). Importantly, receiver operating characteristic analysis confirmed that this CD30⁺OX40⁺ Treg subset could strongly discriminate between CRC patients and healthy subjects with the highest accuracy of 92.3%, an AUC of 0.92, a sensitivity of 88%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 82.35%, and a trade-off value of 3.44%, compared to other Treg subsets. Consistently, multiplex-IHC/IF of tumor-infiltrating Tregs revealed a significant association between high densities of CD30⁺OX40⁺ Tregs and improved overall survival; no such association was found for other subsets. These data suggest a potential role for CD30⁺OX40⁺ Tregs as a diagnostic or prognostic biomarker in CRC.

Expression patterns of the immunomodulatory enzyme arginase 1 in blood, lymph nodes and tumor tissue of early-stage breast cancer patients

Arginase 1 (ARG1) is an important enzyme in amino acid metabolism that also exerts immunoregulatory function. High ARG1 expression, which is associated with cell cycle arrest and functional unresponsiveness in T cells, has been observed after trauma, infections and in cancer patients. We studied ARG1 expression in early-stage breast cancer patients (stage 1, n = 20; stage 2, n = 23) by multi-parametric flow cytometry and immunohistochemistry. Despite a low tumor burden, ARG1 expression was significantly increased in blood-derived myeloid cells of breast cancer patients compared with healthy controls. The ARG1^hi myeloid population in the blood of cancer patients contained a high frequency of CD14⁺ cells and was, therefore, distinct from the granulocytic ARG1⁺ population observed in control individuals. Expression of ARG1 in patient blood cells correlated with tumor grade and was significantly reduced after surgical tumor removal. ARG1⁺ myeloid cells could also be detected in tumors and tumor-draining lymph nodes, where ARG1 expression levels exceeded those measured in the blood. We conclude that even patients with early-stage breast cancer exhibit tumor-related changes of ARG1 expression. The level of ARG1-mediated immunomodulation at this early stage remains to be determined. However, high ARG1 expression is likely to interfere with antitumor T-cell responses and immunotherapeutic interventions, making ARG1 or its downstream effector interesting therapeutic targets.

HMGB1 suppress the expression of IL-35 by regulating Naïve CD4+ T cell differentiation and aggravating Caspase-11-dependent pyroptosis in acute lung injury

OBJECTIVES

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a severe form of inflammatory lung disease. Its development and progression are regulated by cytokines. The purpose of this study was to determine the effects of HMGB1 involved in the regulation of Treg cells and IL-35.

METHODS

A cecal ligation and puncture (CLP)-induced ALI model was used to investigate the changes in IL-35, Tregs, and the expression of RAGE and caspase-11 after HMGB1 inhibition (glycyrrhizin was used as an inhibitor of HMGB1). CD4+ naïve T cells sorted from C57BL/6 mice spleens were cultured to explore the role of HMGB1 in the differentiation from CD4+ naïve T cells to Tregs.

RESULTS

HMGB1 promoted lung injury and uncontrolled inflammation in the CLP mouse model. HMGB1, NF-κB p65, RAGE, and caspase-11 expression in the lungs of CLP mice decreased significantly after pretreatment with glycyrrhizin. We found that the Treg proportion and IL-35 expression were upregulated in the serum and lung of CLP mice after inhibiting HMGB1. In our in vitro experiments, we found that recombinant HMGB1 significantly suppressed the proportion of CD4+CD25+FOXP3+Tregs differentiated from CD4+ naïve T cells.

CONCLUSIONS

The inhibition of HMGB1 increased the proportion of Treg and expression of IL-35 and alleviated lung injury in the CLP-induced ALI model. Furthermore, inhibition of HMGB1 reduced caspase-11-dependent pyroptosis in the lungs of the CLP-induced ALI model.

The role of FOXP3 rs3761548 and rs2294021 polymorphisms in pediatrics acute lymphoblastic leukemia: association with risk and response to therapy

FOXP3 X-linked gene has crucial roles in the development and function of regulatory T cells. We investigated the association of FOXP3 rs3761548, rs3761549 and rs2294021 single nucleotide polymorphisms (SNPs) with acute lymphoblastic leukemia (ALL) susceptibility and response to therapy. Genotyping was performed in 247 patients and 210 healthy subjects. We observed a higher frequency of rs3761548 A carriers and rs2294021 C carriers (p < 0.04) in male patients, and lower frequencies of rs3761548 AC genotype (p = 0.04) and rs2294021 CT genotype (p = 0.01) in female patients compared to controls. ACC (p = 0.04) and ATC haplotypes (p = 0.002) were associated with susceptibility to ALL. There was a significant correlation between the genotypes of rs3761548 and rs2294021 SNPs with event-free survival (EFS) and overall survival (OS). The rs3761548 A genotype in male patients was associated with increased risk of relapse (p < 0.0001), shorter EFS, increased death rate (p = 0.002) and shorter OS compared to C genotype (p = 0.001). Similar significant results were observed for the relation of rs2294021 C genotype with response to therapy in male patients. In females, patients with rs3761548 AC genotype had longer EFS (p = 0.02) and those with rs2294021 CT had longer EFS and OS (p < 0.005). According to haplotype analysis, patients carrying ACC or ATC haplotypes had the highest number of WBCs and shorter EFS or OS, and patients with CCT haplotype had the lowest number of WBCs and longer EFS or OS. These results provided evidence for the impact of these polymorphisms on susceptibility and response to therapy in children with ALL.

Tumor-draining lymph nodes are survival niches that support T cell priming against lymphatic transported tumor antigen and effects of immune checkpoint blockade in TNBC

Triple negative breast cancer (TNBC) is a significant clinical problem to which immunotherapeutic strategies have been applied with limited success. Using the syngeneic E0771 TNBC mouse model, this work explores the potential for antitumor CD8⁺ T cell immunity to be primed extratumorally in lymphoid tissues and therapeutically leveraged. CD8⁺ T cell viability and responses within the tumor microenvironment (TME) were found to be severely impaired, effects coincident with local immunosuppression that is recapitulated in lymphoid tissues in late stage disease. Prior to onset of a locally suppressed immune microenvironment, however, CD8⁺ T cell priming within lymph nodes (LN) that depended on tumor lymphatic drainage remained intact. These results demonstrate tumor-draining LNs (TdLN) to be lymphoid tissue niches that support the survival and antigenic priming of CD8⁺ T lymphocytes against lymph-draining antigen. The therapeutic effects of and CD8⁺ T cells response to immune checkpoint blockade were furthermore improved when directed to LNs within the tumor-draining lymphatic basin. Therefore, TdLNs represent a unique potential tumor immunity reservoir in TNBC for which strategies may be developed to improve the effects of ICB immunotherapy.

Cancer-associated adipocytes as immunomodulators in cancer

Cancer-associated adipocytes (CAAs), as a main component of the tumor-adipose microenvironment (TAME), have various functions, including remodeling the extracellular matrix and interacting with tumor cells or infiltrated leukocytes through a variety of mutual signals. Here, we summarize the primary interplay among CAAs, the immune response and cancer with a focus on the mechanistic aspects of these relationships. Finally, unifying our understanding of CAAs with the immune cell function may be an effective method to enhance the efficacy of immunotherapeutic and conventional treatments.

Comprehensive genomic and immunophenotypic analysis of CD4 T cell infiltrating human triple-negative breast cancer

The aim of this study is to investigate the gene expression module of tumor-infiltrating CD4⁺T cells and its potential roles in modulating immune cell functions in triple-negative breast cancer. Differentially expressed genes were identified by comparison of the expression profile in CD4⁺T cells isolated from tumor tissues and peripheral blood of TNBC patients respectively. The differential expression analysis was conducted using R, and then the functional and pathway enrichment of the DEGs were analyzed using GSEA, followed by integrated regulatory network construction and genetic analysis of tumor-infiltrating immune cells based on a scientific deconvolution algorithm. As a result, abundant Treg and exhausted lymphocytes were detected, accompanied by largely decreased of effector/memory and cytotoxic T cells. Immune-related gene correlation analysis showed that the extent of follicular helper T cells gene expression signatures were inversely associated with those of CD4⁺ naive T cells and CD4⁺ memory resting T cells, but positively correlated with that of CD4⁺ memory activated T cells. In addition, we found five core genes including IFNG, CTLA4, FAS, CXCR6, and JUN were significantly over expressed in CD4⁺ TILs which may contribute to exhaustion of lymphocytes and participate in biological processes associated with regulation of chemotaxis. Study provides a comprehensive understanding of the roles of DEGs associated with the chemotactic and exhausted immunophenotypes of CD4⁺ TILs that are a valuable resource from which future investigation may be carried out to better understand the mechanisms that promote TNBC progression.

Regulatory T Cells: Concept, Classification, Phenotype, and Biological Characteristics

Regulatory T cells (Treg) play an indispensable role in maintaining the body's immune nonresponse to self-antigens and suppressing the body's unwarranted and potentially harmful immune responses. Their absence, reduction, dysfunction, transformation, and instability can lead to numerous autoimmune diseases. There are several distinct subtypes of the Treg cells, although they share certain biological characteristics and have unique phenotypes with different regulatory functions, as well as mechanistic abilities. In this book chapter, we introduce the latest advances in Treg cell subtypes pertaining to classification, phenotype, biological characteristics, and mechanisms. We also highlight the relationship between Treg cells and various diseases, including autoimmune, infectious, as well as tumors and organ transplants.

MMP1 and MMP11 Expression in Peripheral Blood Mononuclear Cells upon Their Interaction with Breast Cancer Cells and Fibroblasts

Tumor-infiltrating immune cells phenotype is associated with tumor progression. However, little is known about the phenotype of the peripheral blood mononuclear cells (PBMC) from breast cancer patients. We investigated MMP1 and MMP11 expression in PBMC from breast cancer patients and we analyzed gene expression changes upon their interaction with cancer cells and cancer-associated fibroblasts (CAF). We measured the impact of PBMC on proinflammatory gene expression in breast cancer cells, normal fibroblast (NF), and CAF and the impact on proliferation and invasiveness capacity of breast cancer cells. Gene expression of MMP1 and MMP11 in PBMC from breast cancer patients (n = 54) and control (n = 28); expression of IL1A, IL6, IL17, IFNβ, and NFĸB in breast cancer cell lines (MCF-7 and MDA-MB-231); and, additionally, IL10 and MMP11 in CAF and NF were analyzed by qRT-PCR before and after co-culture. Our results show the existence of a subpopulation of breast cancer patients (25.9%) with very high levels of MMP11 gene expression in PBMC. Also, gene expression of MMP1 and MMP11 increases in PBMC after co-culture with breast cancer cell lines, NF or CAF. PBMC from healthy or breast cancer patients induce an increased proliferation rate on MCF-7 and an increased invasiveness capacity of MDA-MB-231. Finally, we show a differential expression profile of inflammatory genes in NF and CAF when co-cultured with control or breast cancer PBMC. We have observed that MMPs’ expression in PBMC is regulated by the microenvironment, while the expression of inflammatory genes in NF or CAF is differentially regulated by PBMC. These findings confirm the importance of the crosstalk between stromal cells and suggest that PBMC would play a role in promoting aggressive tumor behavior.

Type I interferons in pancreatic cancer and development of new therapeutic approaches

Immunotherapy has emerged as a new treatment strategy for cancer. However, its promise in pancreatic cancer has not yet been realized. Understanding the immunosuppressive tumor microenvironment of pancreatic cancer, and identifying new therapeutic targets to increase tumor-specific immune responses, is necessary in order to improve clinical outcomes. Type I interferons, e.g. IFN-α and -β, are considered as an important bridge between the innate and adaptive immune system. Thereby, type I IFNs induce a broad spectrum of anti-tumor effects, including immunologic, vascular, as well as direct anti-tumor effects. While IFN therapies have been around for a while, new insights into exogenous and endogenous activation of the IFN pathway have resulted in new IFN-related cancer treatment strategies. Here, we focus on the pre-clinical and clinical evidence of novel ways to take advantage of the type I IFN pathway, such as IFN based conjugates and activation of the STING and RIG-I pathways.

T-regulatory cell/T helper 17 cell imbalance functions as prognostic biomarker of oral squamous cell carcinoma - CONSORT

BACKGROUND

The role of T cells in the pathogenesis of oral squamous cell carcinoma (OSCC) was clarified by examining the levels of differentiated CD4CD25FOXP3 T-regulatory cells (Treg cells) and CD4+IL17+ T helper 17 (Th17) cells in OSCC patients.

METHODS

Flow cytometry was conducted to measure the proportions of Treg/Th17 cells in different sample groups to identify a proper maker indicative of the progression and prognosis of OSCC.

RESULTS

The results showed that a higher Treg/Th17 ratio led to poorer prognosis. Also, the proportions of both Treg cells and Th17 cells were significantly elevated in OSCC patients compared with those in the control groups, suggesting a correlation between Treg/Th17 imbalance and the prognosis of OSCC. Furthermore, the ratios of Treg/Th17 cells in OSCC patients differed at different time points of cancer progression. For example, stage III-IV patients showed the most evident increase in the Treg/Th17 ratio, while the Treg/Th17 ratio in control subjects was the lowest.

CONCLUSIONS

Therefore, a higher ratio of Treg/Th17 indicated the progression of OSCC and a larger tumor size. Therefore, Treg and Th17 imbalance was implicated in OSCC progression.

Distribution of Regulatory T-Cells and Other Phenotypes of T-Cells in Tumors and Regional Lymph Nodes of Colorectal Cancer Patients

BACKGROUND/AIM

Tumor microenvironments consist of many types of immune cells, in which regulatory T-cells (Tregs) are supposed to play important roles to suppress anti-tumor immunity. Regional lymph nodes are essential for antitumor immunity in colorectal cancer (CRC). In this study, we compared the diversity of phenotypes of T-cells in normal tissue and regional lymph nodes in order to determine the immunosuppressive mechanism of lymph node metastasis of CRC.

PATIENTS AND METHODS

Fifty patients were enrolled in this study, and paired samples (tumor tissue, normal tissue, and three regional lymph node samples and as well as non-regional lymph node samples) were obtained from each patient. In each paired-sample set, the proportions of different immune cell types and T-cells expressing immune checkpoint molecules were compared using flow cytometry.

RESULTS

Higher proportions of Tregs [7.58% (4.94%-13.87%) vs. 1.79% (0.03%-5.36%), p<0.001] and lower proportions of INFγ-producing CD4-positive T (iCD4+) cells [21.49% (12.08%-27.35%) vs. 26.55% (15.65%-37.63%), p<0.001] were observed in tumor tissue than in normal mucosa. Parts of regional lymph nodes nearest the tumor had a greater proportion of Tregs [5.86% (4.18%-7.69%)] and lower proportions of iCD4+ [5.94% (3.51%-9.04%)] and INFγ-producing CD8-positive T (iCD8+) cells [21.93% (14.92%-35.90%)] than distant parts of regional lymph nodes and non-regional lymph nodes. Both immune-suppressing molecules (CTLA-4 and PD-1) and immune-promoting molecules (OX-40 and ICOS) tended to be highly expressed in tumor tissue and local lymph nodes.

CONCLUSION

In patients with CRC, regional lymph nodes, especially the parts nearest the tumor, had a higher proportion of Tregs and other suppressive immunophenotypes of T-cells than those located more distantly.

The pleiotropic role of transcription factor STAT3 in oncogenesis and its targeting through natural products for cancer prevention and therapy

Signal transducer and activator of transcription 3 (STAT3) is one of the crucial transcription factors, responsible for regulating cellular proliferation, cellular differentiation, migration, programmed cell death, inflammatory response, angiogenesis, and immune activation. In this review, we have discussed the classical regulation of STAT3 via diverse growth factors, cytokines, G-protein-coupled receptors, as well as toll-like receptors. We have also highlighted the potential role of noncoding RNAs in regulating STAT3 signaling. However, the deregulation of STAT3 signaling has been found to be associated with the initiation and progression of both solid and hematological malignancies. Additionally, hyperactivation of STAT3 signaling can maintain the cancer stem cell phenotype by modulating the tumor microenvironment, cellular metabolism, and immune responses to favor drug resistance and metastasis. Finally, we have also discussed several plausible ways to target oncogenic STAT3 signaling using various small molecules derived from natural products.

Reprogramming the tumour microenvironment by radiotherapy: implications for radiotherapy and immunotherapy combinations

Radiotherapy (RT) is a highly effective anti-cancer therapy delivered to around 50-60% of patients. It is part of therapy for around 40% of cancer patients who are cured of their disease. Until recently, the focus of this anti-tumour efficacy has been on the direct tumour cytotoxicity and RT-induced DNA damage. Recently, the immunomodulatory effects of RT on the tumour microenvironment have increasingly been recognized. There is now intense interest in potentially using RT to induce an anti-tumour immune response, which has led to rethinking into how the efficacy of RT could be further enhanced. Following the breakthrough of immune check point inhibitors (ICIs), a new era of immuno-oncology (IO) agents has emerged and established immunotherapy as a routine part of cancer treatment. Despite ICI improving outcomes in many cancer types, overall durable responses occur in only a minority of patients. The immunostimulatory effects of RT make combinations with ICI attractive to potentially amplify anti-tumour immunity resulting in increased tumour responses and improved outcomes. In contrast, tumours with profoundly immunosuppressive tumour microenvironments, dominated by myeloid-derived cell populations, remain a greater clinical challenge and RT may potentially further enhance the immunosuppression. To harness the full potential of RT and IO agent combinations, further insights are required to enhance our understanding of the role these immunosuppressive myeloid populations play, how RT influences these populations and how they may be therapeutically manipulated in combination with RT to improve outcomes further. These are exciting times with increasing numbers of IO targets being discovered and IO agents undergoing clinical evaluation. Multidisciplinary research collaborations will be required to establish the optimal parameters for delivering RT (target volume, dose and fractionation) in combination with IO agents, including scheduling to achieve maximal therapeutic efficacy.

The Immune Microenvironment in Pancreatic Cancer

The biology of solid tumors is strongly determined by the interactions of cancer cells with their surrounding microenvironment. In this regard, pancreatic cancer (pancreatic ductal adenocarcinoma, PDAC) represents a paradigmatic example for the multitude of possible tumor-stroma interactions. PDAC has proven particularly refractory to novel immunotherapies, which is a fact that is mediated by a unique assemblage of various immune cells creating a strongly immunosuppressive environment in which this cancer type thrives. In this review, we outline currently available knowledge on the cross-talk between tumor cells and the cellular immune microenvironment, highlighting the physiological and pathological cellular interactions, as well as the resulting therapeutic approaches derived thereof. Hopefully a better understanding of the complex tumor-stroma interactions will one day lead to a significant advancement in patient care.

ACSL3-PAI-1 signaling axis mediates tumor-stroma cross-talk promoting pancreatic cancer progression

Pancreatic ductal adenocarcinoma (PDAC) is characterized by marked fibrosis and low immunogenicity, features that are linked to treatment resistance and poor clinical outcomes. Therefore, understanding how PDAC regulates the desmoplastic and immune stromal components is of great clinical importance. We found that acyl-CoA synthetase long-chain 3 (ACSL3) is up-regulated in PDAC and correlates with increased fibrosis. Our in vivo results show that Acsl3 knockout hinders PDAC progression, markedly reduces tumor fibrosis and tumor-infiltrating immunosuppressive cells, and increases cytotoxic T cell infiltration. This effect is, at least in part, due to decreased plasminogen activator inhibitor-1 (PAI-1) secretion from tumor cells. Accordingly, PAI-1 expression in PDAC positively correlates with markers of fibrosis and immunosuppression and predicts poor patient survival. We found that PAI-1 pharmacological inhibition strongly enhances chemo- and immunotherapeutic response against PDAC, increasing survival of mice. Thus, our results unveil ACSL3-PAI-1 signaling as a requirement for PDAC progression with druggable attributes.

PD-1 Expression by Lymph Node and Intratumoral Regulatory T Cells Is Associated with Lymph Node Metastasis in Pancreatic Cancer

Simple Summary

Pancreatic cancer is a devastating disease and among the most immune-resistant tumor types. Single-agent immunotherapy has not demonstrated clinical benefits in pancreatic cancer patients, and combinational therapies targeting multiple mechanisms of immunosuppression are likely needed. T cell activation in lymph nodes is required for the efficacy of immunotherapy. Here, we phenotypically and functionally analyze T cells from tumor-draining lymph nodes, blood and tumors from patients with pancreatic cancer to decipher unknown immunosuppressive mechanisms and to identify potential immunotherapeutic targets.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a mostly immunosuppressive microenvironment. Tumor-draining lymph nodes (TDLN) are a major site for priming of tumor-reactive T cells and also tumor metastasis. However, the phenotype and function of T cells in TDLNs from PDAC patients is unknown. In this study, lymph nodes from the pancreatic head (PH), the hepatoduodenal ligament (HDL) and the interaortocaval (IAC) region were obtained from 25 patients with adenocarcinoma of the pancreatic head. Additionally, tumors and matched blood were analyzed from 16 PDAC patients. Using multicolor flow cytometry, we performed a comprehensive analysis of T cells. CD4⁺ T cells were the predominant T cell subset in PDAC-draining lymph nodes. Overall, lymph node CD4⁺ and CD8⁺ T cells had a similar degree of activation, as measured by CD69, inducible T cell co-stimulator (ICOS) and CD137 (4-1BB) expression and interferon-γ (IFNγ) secretion. Expression of the inhibitory receptor programmed death 1 (PD-1) by lymph node and tumor-infiltrating regulatory T cells (Tregs) correlated with lymph node metastasis. Collectively, Treg cells and PD-1 are two relevant components of the immunosuppressive network in PDAC-draining lymph nodes and may be particularly attractive targets for combinatorial immunotherapeutic strategies in selected patients with node-positive PDAC.

Extracellular vesicles produced by immunomodulatory cells harboring OX40 ligand and 4-1BB ligand enhance antitumor immunity

Genetically modified tumor cells harboring immunomodulators may be used as therapeutic vaccines to stimulate antitumor immunity. The therapeutic benefit of these tumor vaccines is extensively investigated and mechanisms by which they boost antitumor response may be further explored. Tumor cells are large secretors of extracellular vesicles (EVs). These EVs are able to vehiculate RNA and proteins to target cells, and engineered EVs also vehiculate recombinant proteins. In this study, we explore immunomodulatory properties of EVs derived from antitumor vaccines expressing the TNFSF ligands 4-1BBL and OX40L, modulating immune response mediated by immune cells and eliminating tumors. Our results suggest that the EVs secreted by genetically modified tumor cells harboring TNFSF ligands can induce T cell proliferation, inhibit the transcription factor FoxP3, associated with the maintenance of Treg phenotype, and enhance antitumor activity mediated by immune cells. The immunomodulatory extracellular vesicles have potential to be further engineered for developing new approaches for cancer therapy.

G-CSF and G-CSFR Modulate CD4 and CD8 T Cell Responses to Promote Colon Tumor Growth and Are Potential Therapeutic Targets

Cytokines are known to shape the tumor microenvironment and although progress has been made in understanding their role in carcinogenesis, much remains to learn regarding their role in tumor growth and progression. We have identified granulocyte colony-stimulating factor (G-CSF) as one such cytokine, showing that G-CSF is linked with metastasis in human gastrointestinal tumors and neutralizing G-CSF in a mouse model of colitis-associated cancer is protective. Here, we set out to identify the role of G-CSF and its receptor, G-CSFR, in CD4+ and CD8+ T cell responses in the tumor microenvironment. MC38 colon cancer cells were injected into WT, G-CSFR-/- mice, or Rag2-/- mice. Flow cytometry, Real Time PCR and Multiplex cytokine array analysis were used for in vitro T cell phenotype analysis. Adoptive transfer of WT or G-CSFR-/- CD4+ of CD8+ T cells were performed. Mouse tumor size, cytokine expression, T cell phenotype, and cytotoxic activity were analyzed. We established that in G-CSFR-/- mice, tumor growth of MC38 colon cancer cells is significantly decreased. T cell phenotype and cytokine production were also altered, as both in vitro and in vivo approaches revealed that the G-CSF/G-CSFR stimulate IL-10-producing, FoxP3-expressing CD4+ and CD8+ T cells, whereas G-CSFR-/- T cells exhibit increased IFNγ and IL-17A production, leading to increased cytotoxic activity in the tumor microenvironment. Furthermore, peritumoral injection of recombinant IFNγ or IL-17A inhibited colon and pancreas tumor growth compared to controls. Taken together, our data reveal an unknown mechanism by which G-CSF, through its receptor G-CSFR, promotes an inhibitory Treg phenotype that limits tumor immune responses and furthermore suggest that targeting this cytokine/receptor axis could represent a novel therapeutic approach for gastrointestinal, and likely other tumors with high expression of these factors.

Selective inhibition of TGF-β1 produced by GARP-expressing Tregs overcomes resistance to PD-1/PD-L1 blockade in cancer

TGF-β1, β2 and β3 bind a common receptor to exert vastly diverse effects in cancer, supporting either tumor progression by favoring metastases and inhibiting anti-tumor immunity, or tumor suppression by inhibiting malignant cell proliferation. Global TGF-β inhibition thus bears the risk of undesired tumor-promoting effects. We show that selective blockade of TGF-β1 production by Tregs with antibodies against GARP:TGF-β1 complexes induces regressions of mouse tumors otherwise resistant to anti-PD-1 immunotherapy. Effects of combined GARP:TGF-β1/PD-1 blockade are immune-mediated, do not require FcγR-dependent functions and increase effector functions of anti-tumor CD8⁺ T cells without augmenting immune cell infiltration or depleting Tregs within tumors. We find GARP-expressing Tregs and evidence that they produce TGF-β1 in one third of human melanoma metastases. Our results suggest that anti-GARP:TGF-β1 mAbs, by selectively blocking a single TGF-β isoform emanating from a restricted cellular source exerting tumor-promoting activity, may overcome resistance to PD-1/PD-L1 blockade in patients with cancer.

Inhibiting TGF-β1 to increase immune responses against tumors bears the risk of tumor-promoting toxicity. Here the authors show that selectively blocking TGF-β1 produced by immunosuppressive cells is feasible with anti-GARP:TGF-β1 antibodies and improves the efficacy of PD-1 blockade immunotherapy.

Targeted Activation of T Cells with IL-2-Coupled Nanoparticles

Interleukin-2 (IL-2) is a T cell growth factor particularly required in regulatory T cell maintenance and memory T cell responses. High-dose IL-2 treatment was the first FDA-approved immunotherapy for cancer, while low-dose IL-2 administration has shown promise in allograft rejection and autoimmune and inflammatory diseases. However, its pleiotropic nature and the existence of IL-2 receptors with different binding affinity limit its therapeutic application. For an improved clinical applicability of the cytokine, a targeted receptor assignment must, therefore, be achieved. Nanoparticles allow controlling the location and dose of immunomodulating compounds and to specifically address specific receptors through targeted drug binding. In this review article we discuss the IL-2 biology and current clinical application with regard to nanoparticle-based IL-2-mediated manipulation of T cell responses in autoimmunity, chronic inflammation, and cancer.

Glycyrrhizic acid facilitates anti-tumor immunity by attenuating Tregs and MDSCs: An immunotherapeutic approach

Melanoma is one of the most aggressive malignancies and its treatment remains challenging due to its highly metastatic property and availability of limited effective drugs. In addition, immunosuppresive tumor microenvironment (TME) has been identified as major barrier to evoke anti-tumor response in melanoma. Recent studies revealed that immunosuppressive TME is directly correlated with heightened activations of T regulatory cells (Tregs) and Myeloid derived suppressor cells (MDSCs) functions. In this study, we investigated the anti-cancer effect of a triterpenoid, glycyrrhizic acid (GA) on melanoma. Our study revealed that GA not only exhibited anti-proliferative effects on melanoma cells it significantly restricted progression of melanoma tumor. However, the therapeutic efficacy of GA in impressive regression of tumor was found to be directly correlated with induction of apoptosis and modulation of cytokines from Th2 to Th1 type. To unravel the mechanism of anti-melanoma effect of GA, it has been delineated that GA inhibits pSTAT3 to evade anti-tumor suppressive function of Tregs and MDSCs. Downregulation of FOXP3, GITR and CTLA4 in tumor-infiltrating Tregs and inhibition of Cox2, PGE2 and Arginase 1 in intra-tumoral MDSC were evidenced as some of the key events during therapeutic intervention of GA in melanoma management. Moreover, GA effectively restricted advanced stage solid tumor while used in combination with Mycobacterium indicus pranii, a known immunomodulator, which alone is reported to be ineffective to restrict advanced stage solid tumor. Thus, our findings may open up a novel insight of GA as a promising agent in cancer immunotherapy or adjuvant therapy in future.

T-Cell Immunity in Pancreatic Cancer

Worldwide, approximately half a million people are diagnosed with pancreatic cancer every year, with mortality rates of more than 90%. T cells within pancreatic tumors are generally infrequent and incapable of eliciting antitumor immunity. Thus, pancreatic cancer is considered an "immunologically cold" tumor. However, recent studies clearly show that when T-cell immunity in pancreatic cancer is sufficiently induced, T cells become effective weapons. This fact suggests that to improve pancreatic cancer patients' clinical outcomes, we need to unveil the complex immune biology of this disease. In this review, we discuss the elements of tumor immunogenicity in the specific context of pancreatic malignancy.

Regulation and modulation of antitumor immunity in pancreatic cancer

Pancreatic ductal adenocarcinoma carries a dismal prognosis, and outcomes have improved little with modern therapeutics. Checkpoint-based immunotherapy has failed to elicit responses in the vast majority of patients with pancreatic cancer. Alongside tumor cell-intrinsic mechanisms associated with oncogenic KRAS-induced inflammation, the tolerogenic myeloid cell infiltrate has emerged as a critical impediment to adaptive antitumor immune responses. Furthermore, the discovery of an intratumoral microbiome and the elucidation of host-microbe interactions that curtail antitumor immunity also present opportunities for intervention. Here we review the mechanisms of immunotherapy resistance in pancreatic ductal adenocarcinoma and discuss strategies to directly augment T cell responses in parallel with myeloid cell- and microbiome-targeted approaches that may enable immune-mediated control of this malignancy.

Mechanisms of T-Cell Exhaustion in Pancreatic Cancer

T-cell exhaustion is a phenomenon that represents the dysfunctional state of T cells in chronic infections and cancer and is closely associated with poor prognosis in many cancers. The endogenous T-cell immunity and genetically edited cell therapies (CAR-T) failed to prevent tumor immune evasion. The effector T-cell activity is perturbed by an imbalance between inhibitory and stimulatory signals causing a reprogramming in metabolism and the high levels of multiple inhibitory receptors like programmed cell death protein-1 (PD-1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3), and Lymphocyte-activation gene 3 (Lag-3). Despite the efforts to neutralize inhibitory receptors by a single agent or combinatorial immune checkpoint inhibitors to boost effector function, PDAC remains unresponsive to these therapies, suggesting that multiple molecular mechanisms play a role in stimulating the exhaustion state of tumor-infiltrating T cells. Recent studies utilizing transcriptomics, mass cytometry, and epigenomics revealed a critical role of Thymocyte selection-associated high mobility group box protein (TOX) genes and TOX-associated pathways, driving T-cell exhaustion in chronic infection and cancer. Here, we will review recently defined molecular, genetic, and cellular factors that drive T-cell exhaustion in PDAC. We will also discuss the effects of available immune checkpoint inhibitors and the latest clinical trials targeting various molecular factors mediating T-cell exhaustion in PDAC.

Regulatory T cell therapy: Current and future design perspectives

Regulatory T cells (Tregs) maintain immune equilibrium by suppressing immune responses through various multistep contact dependent and independent mechanisms. Cellular therapy using polyclonal Tregs in transplantation and autoimmune diseases has shown promise in preclinical models and clinical trials. Although novel approaches have been developed to improve specificity and efficacy of antigen specific Treg based therapies, widespread application is currently restricted. To date, design-based approaches to improve the potency and persistence of engineered chimeric antigen receptor (CAR) Tregs are limited. Here, we describe currently available Treg based therapies, their advantages and limitations for implementation in clinical studies. We also examine various strategies for improving CAR T cell design that can potentially be applied to CAR Tregs, such as identifying co-stimulatory signalling domains that enhance suppressive ability, determining optimal scFv affinity/avidity, and co-expression of accessory molecules. Finally, we discuss the importance of tailoring CAR Treg design to suit the individual disease.

Tumor invasion in draining lymph nodes is associated with Treg accumulation in breast cancer patients

Tumor-draining lymph node (TDLN) invasion by metastatic cells in breast cancer correlates with poor prognosis and is associated with local immunosuppression, which can be partly mediated by regulatory T cells (Tregs). Here, we study Tregs from matched tumor-invaded and non-invaded TDLNs, and breast tumors. We observe that Treg frequencies increase with nodal invasion, and that Tregs express higher levels of co-inhibitory/stimulatory receptors than effector cells. Also, while Tregs show conserved suppressive function in TDLN and tumor, conventional T cells (Tconvs) in TDLNs proliferate and produce Th1-inflammatory cytokines, but are dysfunctional in the tumor. We describe a common transcriptomic signature shared by Tregs from tumors and nodes, including CD80, which is significantly associated with poor patient survival. TCR RNA-sequencing analysis indicates trafficking between TDLNs and tumors and ongoing Tconv/Treg conversion. Overall, TDLN Tregs are functional and express a distinct pattern of druggable co-receptors, highlighting their potential as targets for cancer immunotherapy.

Local and systemic immunosuppression in pancreatic cancer: Targeting the stalwarts in tumor's arsenal

Late detection, compromised immune system, and chemotherapy resistance underlie the poor patient prognosis for pancreatic ductal adenocarcinoma (PDAC) patients, making it the 3^rd leading cause of cancer-related deaths in the United States. Cooperation between the tumor cells and the immune system leads to the immune escape and eventual establishment of the tumor. For more than 20 years, sincere efforts have been made to intercept the tumor-immune crosstalk and identify the probable therapeutic targets for breaking self-tolerance toward tumor antigens. However, the success of these studies depends on detailed examination and understanding of tumor-immune cell interactions, not only in the primary tumor but also at distant systemic niches. Innate and adaptive arms of the immune system sculpt tumor immunogenicity, where they not only aid in providing an amenable environment for their survival but also act as a driver for tumor relapse at primary or distant organ sites. This review article highlights the key events associated with tumor-immune communication and associated immunosuppression at both local and systemic microenvironments in PDAC. Furthermore, we discuss the approaches and benefits of targeting both local and systemic immunosuppression for PDAC patients. The present articles integrate data from clinical and genetic mouse model studies to provide a widespread consensus on the role of local and systemic immunosuppression in undermining the anti-tumor immune responses against PDAC.

CAR-T Cells Hit the Tumor Microenvironment: Strategies to Overcome Tumor Escape

Chimeric antigen receptor (CAR) T cell therapies have demonstrated remarkable efficacy for the treatment of hematological malignancies. However, in patients with solid tumors, objective responses to CAR-T cell therapy remain sporadic and transient. A major obstacle for CAR-T cells is the intrinsic ability of tumors to evade immune responses. Advanced solid tumors are largely composed of desmoplastic stroma and immunosuppressive modulators, and characterized by aberrant cell proliferation and vascularization, resulting in hypoxia and altered nutrient availability. To mount a curative response after infusion, CAR-T cells must infiltrate the tumor, recognize their cognate antigen and perform their effector function in this hostile tumor microenvironment, to then differentiate and persist as memory T cells that confer long-term protection. Fortunately, recent advances in synthetic biology provide a wide set of tools to genetically modify CAR-T cells to overcome some of these obstacles. In this review, we provide a comprehensive overview of the key tumor intrinsic mechanisms that prevent an effective CAR-T cell antitumor response and we discuss the most promising strategies to prevent tumor escape to CAR-T cell therapy.

Carcinogenesis of Pancreatic Ductal Adenocarcinoma

Although the estimated time for development of pancreatic ductal adenocarcinoma (PDA) is more than 20 years, PDAs are usually detected at late, metastatic stages. PDAs develop from duct-like cells through a multistep carcinogenesis process, from low-grade dysplastic lesions to carcinoma in situ and eventually to metastatic disease. This process involves gradual acquisition of mutations in oncogenes and tumor suppressor genes, as well as changes in the pancreatic environment from a pro-inflammatory microenvironment that favors the development of early lesions, to a desmoplastic tumor microenvironment that is highly fibrotic and immune suppressive. This review discusses our current understanding of how PDA originates.

The role of regulatory T lymphocytes in immune control of MC-2 fibrosarcoma

The role of T regulatory lymphocytes (T_reg) particularly in cancer is well known. The goal of the present study was to determine the contribution of these lymphocytes in the regulation of anti-tumor immunity of CBA/HZgr mice against MC-2 fibrosarcoma (4^th generation of methylcholanthrene induced tumor). The levels of T lymphocytes (CD4+, CD8+ and CD4+CD25+) were determined 8 and 20 days after tumor transplantation. Further, the role of CD4+CD25+ (T_regs) in tumor-host interaction was evaluated in vitro and in vivo by using specific monoclonal antibodies. We found that splenocytes of both control and T_reg depleted tumor bearing mice strongly but differently inhibited growth of tumor cells in vitro. While splenocytes of untreated mice exhibited significant decrease of this activity (from 74.4% to 62.6% and 32.95%), the splenocytes of T_reg depleted mice showed increase of this activity (from 79.5% to 84.3% and 86.2%) from day 6 to day 13 and day 21 after tumor grafting, respectively. Further, upon i.v. injecting specific monoclonal anti-T_reg antibody tumor immediately prior to tumor cell intracutaneous transplantation, the tumor was rejected after initial growth. In treated mice, the incidence of T_reg cells was very low initially, reaching normal values two weeks later. These animals were shown to be resistant to tumor transplantation four months later.

Circulating cells and exosomes in acute myelogenous leukemia and their role in disease progression and survival

Acute myelogenous leukemia (AML) is an aggressive hematological malignancy associated with high rates of mortality. This incidence is due to the complexity in which the AML cells interact with other healthy human cells. These phenomena create an environment that favors the expansion of leukemic cells, which will affect the patient's prognosis. An important aspect is the ability of AML cells to evade immune responses via targeting and signaling immune cells to suppress anti-tumor responses. Many studies have reported that associations among components in the peripheral bloodstream might modulate leukemic progression because AML survival is a fundamental step for recolonizing bone marrow after allogeneic hematopoietic stem cell (HSC) transplantation or chemotherapy. Therefore, we collected the most important data about components that circulate with leukemic blasts and contribute to their survival and proliferation. We also discuss clinical approaches that could be conducted to more effectively treat the disease.

Prognostic significance of baseline T cells, B cells and neutrophil-lymphocyte ratio (NLR) in recurrent ovarian cancer treated with chemotherapy

PURPOSE

Biomarkers are needed to guide treatment decisions in recurrent ovarian cancer, as a high proportion of patients do not benefit from treatments. Data on immune subsets in patients receiving chemotherapy are scarce. We investigated the impact of T cells, B cells, neutrophils and the neutrophil-lymphocyte ratio (NLR) in ovarian cancer patients receiving palliative chemotherapy.

METHODS

Blood samples were collected prospectively at baseline in recurrent ovarian cancer (N = 72) receiving chemotherapy. T cells, B cells, neutrophils, and NLR were analyzed. Primary and secondary endpoints were overall survival (OS) and treatment response, respectively. Cut-offs for T and B cells were predefined.

RESULTS

In patients with low vs. high T and B cells counts, OS was 6.1 months vs 12.0 months (P = 0.017) and 6.1 months vs 12.0 months (P = 0.011, respectively. Low T and B cells analyzed as continuous variables were also associated with unfavorable OS, P = 0.011 and P = 0.007, respectively. Neutrophils had no significant prognostic impact. Median NLR was 4.1. High vs. low NLR was associated with poor survival, 7.4 months vs. 15.9 months (P = 0.012). In multivariate analysis including platinum sensitivity, number of prior lines of chemotherapy, and performance status, high NLR remained an independent poor prognostic factor HR: 2.17 (95% CI 1.21-3.88) (P = 0.009). High NLR was also significantly associated with lack of response, OR 0.15 (95% CI: 0.04-0.51) (P = 0.002).

CONCLUSION

In recurrent ovarian cancer patients undergoing palliative chemotherapy, low T and B lymphocyte counts had an unfavorable prognostic impact. High NLR was associated with lack of response and a poor prognosis, and the parameter may be used in patient counselling and treatment decisions.

Dawn of Monitoring Regulatory T Cells in (Pre-)clinical Studies: Their Relevance Is Slowly Recognised

Regulatory T cells (Tregs) have a prominent role in the control of immune homeostasis. Pharmacological impact on their activity or balance with effector T cells could contribute to (impaired) clinical responses or adverse events. Monitoring treatment-related effects on T cell subsets may therefore be part of (pre-)clinical studies for medicinal products. However, the extent of immune monitoring performed in studies for marketing authorisation and the degree of correspondence with data available in the public domain is not known. We evaluated the presence of T cell immunomonitoring in 46 registration dossiers of monoclonal antibodies indicated for immune-related disorders and published scientific papers. We found that the depth of Treg analysis in registration dossiers was rather small. Nevertheless, data on treatment-related Treg effects are available in public academia-driven studies (post-registration) and suggest that Tregs may act as a biomarker for clinical responses. However, public data are fragmented and obtained with heterogeneity of experimental approaches from a diversity of species and tissues. To reveal the potential added value of T cell (and particular Treg) evaluation in (pre-)clinical studies, more cell-specific data should be acquired, at least for medicinal products with an immunomodulatory mechanism. Therefore, extensive analysis of T cell subset contribution to clinical responses and the relevance of treatment-induced changes in their levels is needed. Preferably, industry and academia should work together to obtain these data in a standardised manner and to enrich our knowledge about T cell activity in disease pathogenesis and therapies. This will ultimately elucidate the necessity of T cell subset monitoring in the therapeutic benefit-risk assessment.