FOXP3 defines regulatory T cells in human tumor and autoimmune disease

Programmed death-1+ T cells and regulatory T cells are enriched in tumor-involved lymph nodes and associated with aggressive features in papillary thyroid cancer

CONTEXT

Recurrent metastatic lymph node (LN) disease is common in patients with papillary thyroid cancer (PTC). Novel prognostic markers may be helpful in guiding a therapeutic approach. Our previous studies revealed that immune suppression is evident in PTC and associated with more severe disease.

OBJECTIVE

To characterize the immune response to metastatic PTC, we assessed CD4(+) T cell polarization in LN. In addition, we investigated the role of programmed death-1 (PD-1) and T cell exhaustion.

DESIGN

Uninvolved (UILN) and tumor-involved lymph nodes (TILN) were sampled ex vivo by fine-needle biopsy. T cell subsets were identified by flow cytometry. In parallel, archived TILN specimens were characterized by immunofluorescence.

SETTING

The study was conducted at the University of Colorado Hospital.

PATIENTS

Data were collected on 94 LN from 19 patients with PTC undergoing neck dissection.

MAIN OUTCOME

T cell subset frequencies were compared in UILN and TILN and assessed for correlation with recurrent disease and extranodal invasion.

RESULTS

Regulatory CD4(+) T cells (Treg) were enriched in TILN compared with UILN and further elevated in TILN from patients with recurrent disease. PD-1(+) T cells were present at high frequency in TILN and markedly enriched in TILN that showed evidence of extranodal invasion. In TILN, Treg frequency correlated with PD-1(+) T cell frequencies. Although PD-1(+) T cells produced interferon-γ, they failed to fully down-regulate CD27 and were not actively proliferating.

CONCLUSIONS

Increased Treg and PD-1(+) T cell frequencies in LN may be indicative of aggressive recurrent PTC. Future prospective studies are necessary to determine the prognostic and therapeutic value of these findings in PTC.

The prognostic value of FoxP3+ tumor-infiltrating lymphocytes in cancer: a critical review of the literature

CD8+ tumor-infiltrating lymphocytes (TIL) are associated with survival in a variety of cancers. A second subpopulation of TIL, defined by forkhead box protein P3 (FoxP3) expression, has been reported to inhibit tumor immunity, resulting in decreased patient survival. On the basis of this premise, several groups are attempting to deplete FoxP3+ T cells to enhance tumor immunity. However, recent studies have challenged this paradigm by showing that FoxP3+ T cells exhibit heterogeneous phenotypes and, in some cohorts, are associated with favorable prognosis. These discrepant results could arise from differences in study methodologies or the biologic properties of specific cancer types. Here, we conduct the first systematic review of the prognostic significance of FoxP3+ T cells across nonlymphoid cancers (58 studies from 16 cancers). We assessed antibody specificity, cell-scoring strategy, multivariate modeling, use of single compared with multiple markers, and tumor site. Two factors proved important. First, when FoxP3 was combined with one additional marker, double-positive T cells were generally associated with poor prognosis. Second, tumor site had a major influence. FoxP3+ T cells were associated with poor prognosis in hepatocellular cancer and generally good prognosis in colorectal cancer, whereas other cancer types were inconsistent or understudied. We conclude that FoxP3+ T cells have heterogeneous properties that can be discerned by the use of additional markers. Furthermore, the net biologic effects of FoxP3+ T cells seem to depend on the tumor site, perhaps reflecting microenvironmental differences. Thus, depletion of FoxP3+ T cells might enhance tumor immunity in some patient groups but be detrimental in others.

Mitigating age-related immune dysfunction heightens the efficacy of tumor immunotherapy in aged mice

Although cancer tends to affect the elderly, most preclinical studies are carried out in young subjects. In this study, we developed a melanoma-specific cancer immunotherapy that shows efficacy in aged but not young hosts by mitigating age-specific tumor-associated immune dysfunction. Both young and aged CD4(+)CD25(hi) regulatory T cells (Treg) exhibited equivalent in vitro T-cell suppression and tumor-associated augmentation in numbers. However, denileukin diftitox (DT)-mediated Treg depletion improved tumor-specific immunity and was clinically effective only in young mice. DT-mediated Treg depletion significantly increased myeloid-derived suppressor cell (MDSC) numbers in aged but not young mice, and MDSC depletion improved tumor-specific immunity and reduced tumor growth in aged mice. Combining Treg depletion with anti-Gr-1 antibody was immunologically and clinically more efficacious than anti-Gr-1 antibody alone in aged B16-bearing mice, similar to Treg depletion alone in young mice. In contrast, DT increased MDSCs in young and aged mice following MC-38 tumor challenge, although effects were greater in aged mice. Anti-Gr-1 boosted DT effects in young but not aged mice. Aged antitumor immune effector cells are therefore competent to combat tumor when underlying tumor-associated immune dysfunction is appropriately mitigated, but this dysfunction varies with tumor, thus also varying responses to immunotherapy. By tailoring immunotherapy to account for age-related tumor-associated immune dysfunctions, cancer immunotherapy for aged patients with specific tumors can be remarkably improved.

What are regulatory T cells (Treg) regulating in cancer and why?

The role regulatory T cells (Treg) play in cancer development and progression is not clear. Earlier evidence suggested that CD4(+)FOXP3(+)CD25(high) Treg accumulate in tumors and the peripheral blood of patients with cancer and through suppression of anti-tumor immune responses promote tumor growth. However, more recent data indicate that in certain cancers, such as colorectal carcinoma (CRC), Treg suppress bacteria-driven inflammation which promotes carcinogenesis and thus benefit the host. Treg appear to play a dual role in cancer. This might explain why the frequency and functions of Treg are associated with a poor prognosis in some cancers but with favorable outcome in others. The clinical and prognostic significance of Treg in cancer depends on environmental factors, including infectious agents, tumor-derived products and locally-produced cytokines, which shape the nature of immune responses, including Treg generation, recruitment and survival. Adaptive or inducible (i) Treg or Tr1 are the major subset(s) of Treg present in cancer. These iTreg are a distinct subset of regulatory cells that phenotypically and functionally differ from FOXP3(+) natural (n) Treg responsible for peripheral tolerance. They mediate powerful suppression of effector T cells via diverse mechanisms, produce immunosuppressive cytokines, notably TGF-β as well as prostaglandin E2 and adenosine, and are resistant to apoptosis or oncological therapies. Strategies for silencing of Tr1 in patients with cancer will require novel approaches that can selectively deplete these cells or block molecular pathways they utilize.

In breast cancer, a high ratio of tumour-infiltrating intraepithelial CD8+ to FoxP3+ cells is characteristic for the medullary subtype

AIMS

Medullary breast cancer (MBC) is a biologically distinct subtype of breast cancer characterized by prominent lymphocytic infiltrates and a favourable clinical outcome. Tumour-infiltrating CD8+ effector T cells may contribute to the good prognosis of this type of cancer; however, certain subtypes of lymphocyte, such as FoxP3+ regulatory T cells (Tregs), can also suppress antitumour immunity.

METHODS AND RESULTS

We determined tumour infiltration by FoxP3+, CCL22+ and CD8+ cells in paraffin-embedded sections of MBC, and, as a reference, in samples of grade 3 ductal, lobular and mucinous breast cancer. All analysed MBCs were strongly infiltrated by FoxP3+ cells, whereas only weak infiltrates were detected in ductal or lobular breast cancer. This finding was unexpected, given the good prognosis of MBC. Strikingly, the number of CD8+ T cells exceeded the number of FoxP3+ cells in MBC (ratio of CD8+ to FoxP3+ cells of 2.6), whereas equal amounts of both cell types were found in ductal breast cancer (ratio of CD8+ to FoxP3+ cells of 1.1). In both types of breast cancer, we also detected cells expressing the Treg-attracting chemokine CCL22.

CONCLUSIONS

In breast cancer, a predominance of tumour-infiltrating CD8+ over FoxP3+ cells was observed in MBC. Thus, the ratio of CD8+ to FoxP3+ cells rather than the absolute number of intratumoral FoxP3+ cells may be predictive for the clinical outcome of cancer.

Targeting regulatory T cells

Cancers express tumor-associated antigens that should elicit immune response to antagonize the tumor growth, but spontaneous immune rejection of established cancer is rare, suggesting an immunosuppressive environment hindering host antitumor immunity. Among the specific and active tumor-mediated mechanisms, CD4(+)CD25(high) T regulatory cells (Treg) are important mediators of active immune evasion in cancer. In this review, we will discuss Treg subpopulations and the mechanisms of their suppressive functions. Treg depletion improves endogenous antitumor immunity and the efficacy of active immunotherapy in animal models for cancer, suggesting that inhibiting Treg function could also improve the limited successes of human cancer immunotherapy. We will also discuss specific strategies for devising effective cancer immunotherapy targeting Treg.

T lymphocyte recruitment into renal cell carcinoma tissue: a role for chemokine receptors CXCR3, CXCR6, CCR5, and CCR6

BACKGROUND

Evidence suggests that some patients with renal cell carcinoma (RCC) respond to immunomodulatory therapies that activate T lymphocytes. A prerequisite for effective T cell therapy is efficient targeting of effector T cells to the tumour site, yet the molecular basis of T cell recruitment to RCC is unknown. Furthermore, some T cells that naturally infiltrate this cancer are regulatory T cells (Tregs) that may suppress antitumour immune responses.

OBJECTIVE

Determine the mechanisms of effector and regulatory T cell recruitment to RCC to allow targeted therapy that promotes local anti-tumour immunity.

DESIGN, SETTING, AND PARTICIPANTS

Tumour-infiltrating and peripheral blood T cells were collected from 70 patients undergoing nephrectomy for RCC.

MEASUREMENTS

T cells were analysed by multicolour flow cytometry for expression of 19 chemokine receptors and 7 adhesion molecules. Receptors that were expressed at higher levels on tumour-infiltrating lymphocytes (TILs) compared with matched peripheral blood lymphocytes (PBLs) were analysed further for their ability to mediate migration responses in TILs and for expression of corresponding ligands in tumour tissue.

RESULTS AND LIMITATIONS

Three chemokine receptors-CCR5, CXCR3, and CXCR6-were significantly overexpressed on TILs compared with matched PBLs (n=16 cases) and were capable of promoting migration in vitro. Their corresponding ligands CCL4-5, CXCL9-11, and CXCL16 were all detected in RCC tissue. However, since they were present in all cases studied, it was not possible to correlate ligand expression with levels of T cell infiltration. Foxp3(+) Tregs were enriched within TILs compared with matched PBLs and expressed high levels of CCR5, CXCR3, and CXCR6, as well as CCR6, the ligand for which (CCL20) was detectable in RCC tissue.

CONCLUSIONS

Our data support a role for CCR5, CXCR3, and CXCR6 in the selective recruitment of T cells into RCC tissue and, together with CCR6, in the recruitment of Tregs.

Variation of tumor-infiltrating lymphocytes in human cancers: controversy on clinical significance

Tumors develop and progress under the influence of a microenvironment comprising a variety of immune cell subsets and their products. Recent studies have shown that tumor-infiltrating lymphocytes (TILs) are not randomly distributed, but organized to accumulate more or less densely in different regions within tumors, and interact with each other. Substantial evidence has suggested that not only CD8(+) and/or CD4(+) αβ T cells but also other lymphocyte subsets, including γδ T cells, B cells, NK cells, and NKT cells, infiltrate tumor tissues in variable quantities and play a key role in the regulation of antitumor immunity. In this article, we summarize available information regarding the diversity and composition of TILs, which may positively or negatively affect tumor growth and patient clinical outcomes. The clinical significance of TILs in human cancers remains unclear and is a subject of considerable controversy; largely due to the lack of functional data for TILs, as well as due to enormous variability of TILs in different tumors. A great deal more functional data about TILs needs to be obtained for individual tumors before TILs can be considered as a prognostic parameter in human cancers.

Pathway-based analysis of a melanoma genome-wide association study: analysis of genes related to tumour-immunosuppression

Systemic immunosuppression is a risk factor for melanoma, and sunburn-induced immunosuppression is thought to be causal. Genes in immunosuppression pathways are therefore candidate melanoma-susceptibility genes. If variants within these genes individually have a small effect on disease risk, the association may be undetected in genome-wide association (GWA) studies due to low power to reach a high significance level. Pathway-based approaches have been suggested as a method of incorporating a priori knowledge into the analysis of GWA studies. In this study, the association of 1113 single nucleotide polymorphisms (SNPs) in 43 genes (39 genomic regions) related to immunosuppression have been analysed using a gene-set approach in 1539 melanoma cases and 3917 controls from the GenoMEL consortium GWA study. The association between melanoma susceptibility and the whole set of tumour-immunosuppression genes, and also predefined functional subgroups of genes, was considered. The analysis was based on a measure formed by summing the evidence from the most significant SNP in each gene, and significance was evaluated empirically by case-control label permutation. An association was found between melanoma and the complete set of genes (p(emp)=0.002), as well as the subgroups related to the generation of tolerogenic dendritic cells (p(emp)=0.006) and secretion of suppressive factors (p(emp)=0.0004), thus providing preliminary evidence of involvement of tumour-immunosuppression gene polymorphisms in melanoma susceptibility. The analysis was repeated on a second phase of the GenoMEL study, which showed no evidence of an association. As one of the first attempts to replicate a pathway-level association, our results suggest that low power and heterogeneity may present challenges.

Bone marrow and the control of immunity

Bone marrow is thought to be a primary hematopoietic organ. However, accumulated evidences demonstrate that active function and trafficking of immune cells, including regulatory T cells, conventional T cells, B cells, dendritic cells, natural killer T (NKT) cells, neutrophils, myeloid-derived suppressor cells and mesenchymal stem cells, are observed in the bone marrow. Furthermore, bone marrow is a predetermined metastatic location for multiple human tumors. In this review, we discuss the immune network in the bone marrow. We suggest that bone marrow is an immune regulatory organ capable of fine tuning immunity and may be a potential therapeutic target for immunotherapy and immune vaccination.

Adalimumab treatment in Crohn's disease does not induce early changes in regulatory T cells

OBJECTIVE

Anti-TNF-α antibodies has been suggested to modulate regulatory T cell (Treg) percentages in rheumatoid arthritis, but results from studies of Crohn's disease (CD) are conflicting. We investigated dynamic changes of circulating Tregs in CD during treatment with the anti-TNF-α-antibody adalimumab (Humira®, Abbott Laboratories A/S, Emdrupvej 28C, DK-2100 Copenhagen).

MATERIAL AND METHODS

Blood samples from 26 CD patients were analysed using flow cytometry before and 1 and 26 weeks after initiation of adalimumab treatment to determine the percentage of Tregs among CD4+ T cells.

RESULTS

In spite of a significant decline in disease activity scores and biochemical markers of inflammation, during the first week of treatment, we did not observe early modulating effects of adalimumab on Treg percentages. However, we found a long-term increase in Treg percentages in responders who had low Treg percentages (<5%) at baseline (p = 0.04). Treg percentage was inversely associated with disease activity (CD activity index or CDAI) (Spearman's rank correlation, ρ = -0.47, p = 0.02). High Treg percentages among CD4+ T cells at baseline predicted clinical response to adalimumab.

CONCLUSIONS

Adalimumab treatment did not induce early modulatory effects on Treg percentage, even in responders. This finding suggests that adalimumab does not have a direct or selective effect on Tregs. However, Treg percentage was associated with disease activity and high Treg percentage predicted response to adalimumab.

The phenotypic and functional consequences of tumour necrosis factor receptor type 2 expression on CD4(+) FoxP3(+) regulatory T cells

Cytokine receptors expressed by CD4(+)  FoxP3(+) regulatory T cells (Treg cells) not only serve as a phenotypic marker for the identification of this important population of immunosuppressive cells, they also promote the function of Treg cells. CD25, the α-chain of interleukin-2 receptor, is a prototype of such a receptor, which enables Treg cells to be activated by interleukin-2. We and others have found that tumour necrosis factor receptor type 2 (TNFR2) is another important cytokine receptor preferentially expressed by Treg cells with important phenotypic and functional roles. TNFR2 is preferentially expressed by highly functional human and mouse Treg cells, and mediates the activating effect of TNF on Treg cells. We review here the studies of the regulation of expression of TNFR2 on functional Treg cells as well as on CD4(+)  FoxP3(-) effector T cells (Teff cells). We document the critical role of this receptor in the activation, proliferative expansion and survival of Treg cells. The contribution of TNFR2 expression on Treg and Teff cells to the beneficial and detrimental effects of anti-TNF treatment in autoimmune disorders will also be discussed.

Prognostic role of FOXP3+ regulatory T cells infiltrating human carcinomas: the paradox of colorectal cancer

The accumulation of regulatory T cells (Tregs) at high density in various human carcinomas is generally associated with a poor prognosis, as expected from their capacity to inhibit antitumor immunity. Surprisingly, in patients bearing colorectal carcinoma (CRC), high regulatory T-cell infiltration is associated with a favorable prognosis, as shown by the analysis of seven clinical studies. To explain this paradox, we emphasize a putative role of the dense microbiological flora present in the large intestine with a trend toward translocation through the tumor. This microbiological hazard requires a T-cell-mediated inflammatory anti-microbial response that involves Th17 cells and can thereby promote cancer growth. This Th17-cell-dependent proinflammatory and tumor-enhancing response can be attenuated by Tregs, thus constituting a possible explanation for their favorable role in CRC prognosis. The link between a high density of FOXP3-positive cells in CRC immune infiltrates and favorable prognosis should lead us to consider tumor infiltrating Tregs as allies to be respected, rather than enemies to be destroyed during trials of CRC treatment.

The numbers of FoxP3+ lymphocytes in sentinel lymph nodes of breast cancer patients correlate with primary tumor size but not nodal status

Regulatory T cells, lymphocytes marked by expression of the transcription factor Forkhead Box Protein P3 (FoxP3), inhibit the activation of tumor-specific T cells in tumor-draining lymph nodes. Immunohistochemical analyses of sentinel lymph nodes (SLNs) from 104 breast cancer patients showed a significant association (p = .0028, Pearson correlation) between the number of FoxP3+ cells and the size of primary breast invasive ductal carcinoma. In contrast, there was no correlation between the number of FoxP3+ cells and the presence of SLN metastases, or other clinicopathological parameters. These results suggest the presence of an immune suppressive environment in SLNs of larger tumors.

Increase in circulating CD4⁺CD25⁺Foxp3⁺ T cells in patients with Philadelphia-negative chronic myeloproliferative neoplasms during treatment with IFN-α

Recent reports have described complete or major molecular remission in patients with polycythemia vera after long-term treatment with the immunomodulatory agent IFN-α2. Accordingly, there are reasons to believe that the immune system is a key player in eradicating the JAK2 mutated clone in these patients. Foxp3(+) regulatory T cells play a pivotal role in maintaining immune homeostasis and, importantly, preventing immune reactivity to self-antigens; however, their suppressive activity can compromise an effective antitumor immune response, and high frequencies of regulatory T cells in peripheral blood have been reported in both hematologic and solid cancers. We have analyzed the number, phenotype, and function of circulating CD4(+)CD25(+)Foxp3(+) T cells in patients with chronic myeloproliferative neoplasms. Surprisingly, we found a marked expansion of this subset of lymphocytes in patients treated with IFN-α2 (13.0%; 95% confidence interval [CI] 10.8% to 15.2%) compared with healthy donors (6.1%; 95% CI 4.9% to 7.2%), patients with untreated chronic myeloproliferative neoplasms (6.9%; 95% CI 5.8% to 7.4%), or patients treated with hydroxyurea (5.8%; 95% CI 4.3% to 7.4%; P < .0001).

Conversion of intratumoral regulatory T cells by human gastric cancer cells is dependent on transforming growth factor-β1

BACKGROUND AND OBJECTIVES

Regulatory T cells (Treg) inhibits immune responses mediated by T cells. This study aimed to investigate whether Treg are accumulated in human gastric cancer tissue and the mechanism of Treg induction by gastric cancer cells.

METHODS

Tissue infiltrated leukocytes from gastric adenocarcinomas were subjected to flow cytometry and immunohistochemistry. Percentage, phenotype, function, and clinical relevance of Treg were analyzed. TGF-β1 production by cancer cells was determined by Western blot and in vitro co-culture experiments were performed to mimic gastric cancer microenvironment.

RESULTS

The percentages of CD4(+) Foxp3(+) T cells in gastric cancer tissues were significantly higher than those from adjacent non-tumor gastric tissues (P < 0.05). The results of classical Treg phenotype and proliferation assay supported that the elevated CD4(+) Foxp3(+) T cells represents a suppressive Treg population. High proportion of Treg is correlated to advance TNM stage and reduced survival. Primary gastric cancer cells produced abundance of TGF-β1 which was responsible for conversion of Treg.

CONCLUSION

The proportion of functional Treg is elevated in human gastric cancer and related to poor prognosis. Gastric cancer cells directly convert CD4(+) naive T cells to Treg by TGF-β1, suggesting a possible mechanism through which tumor cells evade the immune system.

Intratumoral regulatory T cells alone or in combination with cytotoxic T cells predict prognosis of hepatocellular carcinoma after resection

Tumor-infiltrating lymphocytes (TILs) represent the host immune response to cancer. CD8(+) cytotoxic T cells (CTLs) have a central role in the elimination of tumors, while regulatory T cells (Tregs) can suppress the immune reaction. The aim of this study was to investigate the prognostic value of TILs, especially Tregs and CTLs, in hepatocellular carcinoma (HCC) patients after resection. CD3(+), CD4(+), CD8(+), and FoxP3(+) TILs were assessed by immunohistochemistry in tumor tissue from 141 randomly selected HCC patients. Prognostic effects of low- or high-density TIL subsets were evaluated by Kaplan-Meier and Cox regression analysis using the median values as cutoff. The density of intratumoral Tregs (P = 0.040) and peritumoral CTLs (P = 0.004) were an independent factor for overall survival (OS), but not for disease-free survival (DFS). The density of CD3(+) and CD4(+) TILs, and the prevalence of Tregs and CTLs were associated with neither OS nor DFS. The presence of low intratumoral Tregs with high intratumoral CTLs was a negative independent prognostic factor for OS (P = 0.001), while that of low intratumoral Tregs and low peritumoral CTLs independently correlated with improved DFS (P = 0.008). Moreover, the combined analysis of Tregs and CTLs displayed better prognostic performances than any of them alone. Additionally, higher density of intratumoral Tregs correlated with both the presence of liver cirrhosis (P = 0.025) and increased tumor size (P = 0.050). Tregs within tumor environment are promising prognostic parameters for HCC patients, and their combination with CTLs can predict prognosis more effectively.

Separation of human CD4+CD39+ T cells by magnetic beads reveals two phenotypically and functionally different subsets

OBJECTIVE

The ectonucleotidase CD39 is an enzyme involved in adenosine production. Its surface expression on human regulatory T cells (Treg) allows for their flow-cytometry-based isolation from peripheral blood. To further develop and improve this method on a scale supporting translational studies, we introduced capture of CD39(+) Treg on magnetic immunobeads.

METHODS

Peripheral blood mononuclear cells (PBMC) obtained from healthy donors were used for negative selection of CD4(+) T cells on AutoMACS using antibodies (Abs) specific for all lineage(+) cells. CD4(+)CD39(+) Treg were captured by biotin-conjugated anti-CD39 Abs and anti-biotin Ab-coated magnetic beads. Isolated CD4(+)CD39(+) T cells were phenotyped by flow cytometry for Treg-associated markers: CD39, CD73, FOXP3, CD25, CTLA-4, CCR4, CD45RO and CD121a or for the absence of CD127 and CD49d. CFSE-based proliferation assays and ATP hydrolysis were used to measure Treg functions.

RESULTS

The purity, recovery and viability of the separated CD4(+)CD39(+) T cells were satisfactory. The isolated CD4(+)CD39(+) T cell population consisted of FOXP3(+)CD25(+) T cells which hydrolyzed exogenous ATP and suppressed autologous CD4(+) T cell proliferation and of FOXP3(neg)CD25(neg) T cells without suppressor function. The same two subsets were detectable by flow cytometry in normal PBMC, gating on CD4(+)CD39(+), CD4(+)CD127(neg), CD4(+)CD49d(neg) or CD4(+)CD25(high) Treg.

CONCLUSION

CD4(+)CD39(+) Treg capture on immunobeads led to a discovery of two CD39(+) subsets. Similar to CD39(+) Treg in the peripheral blood, half of these cells are CD25(+)FOXP3(+) active suppressor cells, while the other half are CD25(neg)FOXP3(neg) and do not mediate suppression.

Th17 and Foxp3(+) T regulatory cell dynamics and distribution in myelodysplastic syndromes

Foxp3(+) T regulatory cells (Tregs) and Th17 cells accumulate synchronously at tumor sites during cancer progression, where their interplay is apparently affecting the efficiency of the antitumor response. In myelodysplastic syndromes, a hematopoietic malignancy of myeloid origin, Tregs are highly increased in the late stages of the disease (L-MDS), but the mechanisms driving Treg expansion and the interaction between Treg and Th17 cell dynamics are still unknown. We demonstrate that the proliferative capacity of Tregs is deficient during the early MDS stages (E-MDS), while in L-MDS it returns to normal levels. In addition, synchronously to Treg expansion, L-MDS patients exhibit increased numbers of functionally competent bone marrow IL-17(+) and FOXP3(+)/IL-17(+) cells, in contrast to E-MDS patients, where Th17 cells are significantly decreased and hypofunctional. Our findings suggest similar kinetics of Treg and Th17 cells between MDS and solid tumors, indicating a common immune pathogenetic pathway between diverse cancer types.

IL-17+ regulatory T cells in the microenvironments of chronic inflammation and cancer

Foxp3(+)CD4(+) regulatory T (Treg) cells inhibit immune responses and temper inflammation. IL-17(+)CD4(+) T (Th17) cells mediate inflammation of autoimmune diseases. A small population of IL-17(+)Foxp3(+)CD4(+) T cells has been observed in peripheral blood in healthy human beings. However, the biology of IL-17(+)Foxp3(+)CD4(+) T cells remains poorly understood in humans. We investigated their phenotype, cytokine profile, generation, and pathological relevance in patients with ulcerative colitis. We observed that high levels of IL-17(+)Foxp3(+)CD4(+) T cells were selectively accumulated in the colitic microenvironment and associated colon carcinoma. The phenotype and cytokine profile of IL-17(+)Foxp3(+)CD4(+) T cells was overlapping with Th17 and Treg cells. Myeloid APCs, IL-2, and TGF-β are essential for their induction from memory CCR6(+) T cells or Treg cells. IL-17(+)Foxp3(+)CD4(+) T cells functionally suppressed T cell activation and stimulated inflammatory cytokine production in the colitic tissues. Our data indicate that IL-17(+)Foxp3(+) cells may be "inflammatory" Treg cells in the pathological microenvironments. These cells may contribute to the pathogenesis of ulcerative colitis through inducing inflammatory cytokines and inhibiting local T cell immunity, and in turn may mechanistically link human chronic inflammation to tumor development. Our data therefore challenge commonly held beliefs of the anti-inflammatory role of Treg cells and suggest a more complex Treg cell biology, at least in the context of human chronic inflammation and associated carcinoma.

Regulatory and activated T cells in human Schistosoma haematobium infections

Acquired immunity against helminths is characterised by a complex interplay between the effector Th1 and Th2 immune responses and it slowly manifests with age as a result of cumulative exposure to parasite antigens. Data from experimental models suggest that immunity is also influenced by regulatory T cells (Treg), but as yet studies on Treg in human schistosome infections are limited. This study investigated the relationship between schistosome infection intensity and the two cell populations regulatory T cells (TREG: CD4(+(dim))CD25(+(high))FOXP3(+)CD127(low)), and activated (Tact: CD4(+)CD25(+)FOXP3(-)) T cells in Zimbabweans exposed to Schistosoma haematobium parasites. Participants were partitioned into two age groups, young children (8-13 years) in whom schistosome infection levels were rising to peak and older people (14+ years) with declining infection levels. The relationship between Tact proportions and schistosome infection intensity remained unchanged with age. However Treg proportions rose significantly with increasing infection in the younger age group. In contrast Treg were negatively correlated to infection intensity in the older age group. The relative proportions of regulatory T cells differ significantly between young individuals in whom high infection is associated with an enhanced regulatory phenotype and older infected patients in whom the regulatory response is attenuated. This may influence or reflect different stages of the development of protective schistosome acquired immunity and immunopathogenesis.

T regulatory cells control T-cell proliferation partly by the release of soluble CD25 in patients with B-cell malignancies

Interleukin-2 (IL-2) is one of the most studied cytokines driving T-cell proliferation, activation and survival. It binds to the IL-2 receptor consisting of three chains, the α (CD25), β and common γ (γc). The binding of the CD25 chain to IL-2 is necessary to expose high-affinity binding sites for the β and γc chains, which, in turn, are responsible for downstream signalling. A high level of soluble CD25 (sCD25) has been associated with a poor prognosis in patients with non-Hodgkin's lymphoma. The function and source of origin of this soluble receptor is not well investigated. In the present study we hypothesized that T regulatory (Treg) cells may release CD25 to act as a decoy receptor for IL-2, thereby depriving T-effector cells of IL-2. Peripheral blood from patients with B-cell malignancies (n = 26) and healthy controls (n = 27) was investigated for the presence and function of FoxP3(+) Treg cells and sCD25 by multi-colour flow cytometry and enzyme-linked immunosorbent assay. Further, the proliferative capacity of T cells was evaluated with or without the presence of recombinant sCD25. The results demonstrate that Treg cells from patients had lower CD25 expression intensity and that they released CD25 in vitro. Further, high levels of Treg cells correlated with sCD25 plasma concentration. Recombinant sCD25 could suppress T-cell proliferation in vitro. In conclusion, the release of sCD25 by Treg cells may be a mechanism to deprive IL-2 and thereby inhibit anti-tumour T-cell responses.

Immune response in ovarian cancer: how is the immune system involved in prognosis and therapy: potential for treatment utilization

Ovarian cancer is one of the leading causes of cancer-related death among women. Resistance to the disease occurs in more than 70% of the cases even after treated with chemotherapy agents such as paclitaxel- and platinum-based agents. The immune system is increasingly becoming a target for intense research in order to study the host's immune response against ovarian cancer. T cell populations, including NK T cells and Tregs, and cytokines have been associated with disease outcome, indicating their increasing clinical significance, having been associated with prognosis and as markers of disease progress, respectively. Harnessing the immune system capacity in order to induce antitumor response remains a major challenge. This paper examines the recent developments in our understanding of the mechanisms of development of the immune response in ovarian cancer as well as its prognostic significance and the existing experience in clinical studies.

Therapy with anti-TNFα antibody enhances number and function of Foxp3(+) regulatory T cells in inflammatory bowel diseases

BACKGROUND

Inflammatory bowel diseases (IBDs) are associated with up-regulation of TNFα, hyperactivation of proinflammatory effector T cells (Teffs) and inefficient control by regulatory CD4(+) CD25(+) Foxp3(+) T cells (Tregs). The aim of this prospective study was to investigate the short-term impact of treatment of IBD patients with anti-TNFα antibodies (infliximab or adalimumab) on the frequency, phenotype, and suppressive function of Tregs.

METHODS

Active IBD patients including 16 with Crohn's disease and 9 with ulcerative colitis were treated with anti-TNFα mAb. PBMCs were harvested immediately before and 2 weeks after the first injection. The frequency and phenotype of circulating CD4(+) CD25(+) Foxp3(+) Tregs were analyzed by flow cytometry, and their suppressive function was assessed by the ability of purified CD4(+) CD25(+) CD127(-) Tregs to inhibit the proliferation of allogenic CD4(+) CD25(-) Teffs.

RESULTS

CD4(+) CD25(+) Foxp3(+) Treg frequency was significantly lower in active IBD patients than in controls (2.8% ± 0.4% vs. 4.6% ± 0.6%, respectively; P = 0.01). On day 14 following the first anti-TNFα infusion, the frequency of circulating Tregs was significantly enhanced in IBD patients (4.0% ± 0.5% vs. 2.8% ± 0.4%, before treatment; P = 0.001), with a 2- to 3-fold increase in the intensity of Foxp3 expression. In addition, infliximab treatment enhanced the suppressive function of circulating Tregs, as shown by inhibition of Teff proliferation at a 1:8 Treg/Teff ratio (28% ± 5% vs. 66% ± 10%, after treatment; P = 0.04).

CONCLUSIONS

These data demonstrate that anti-TNFα treatment of active IBD rapidly enhances the frequency of functional Foxp3(+) Tregs in blood and potentiates their suppressive function. This indicates that Treg potentiation may represent an unanticipated outcome of anti-TNFα biotherapy in IBD.

Increased frequencies of CD4+ CD25+ FOXP3+ regulatory T cells in human nasal inverted papilloma

BACKGROUND

The purpose of this study was to investigate the presence of CD4(+) CD25(+) FOXP3(+) regulatory T (Treg) cells both in peripheral blood and local tumors in patients with nasal inverted papilloma (NIP).

METHODS

By using flow cytometry, the frequencies of CD4(+) CD25(+) FOXP3(+) Treg cells in both peripheral blood and tissues from 18 patients with NIP and 8 control subjects were determined. CCL22 and CCL17 proteins in NIP tumors were analyzed by using enzyme-linked immunosorbent assay. The suppressive capacity of Treg cells was estimated by WST-8 and enzyme-linked immunosorbent assay (ELISA; interferon-gamma [IFN-γ] and interleukin-4 [IL-4]) analysis.

RESULTS

Patients with NIP showed increased CD4(+) CD25(+) FOXP3(+) Treg cell frequencies in tumor tissues and CD4(+) T cell fraction rather than in peripheral blood. CCL22 increased in NIP tumors. Phytohemagglutinin (PHA)-induced proliferation and cytokine production of CD4(+) CD25(-) T cells were suppressed equally well by CD4(+) CD25(high) cells from both patients with NIP and controls.

CONCLUSION

Our study demonstrated the increased frequencies of CD4(+) CD25(+) FOXP3(+) Treg cells in NIP tumors, which might be influenced by CCL22.

Increased prevalence of interleukin-17-producing CD4(+) tumor infiltrating lymphocytes in human oral squamous cell carcinoma

BACKGROUND

T helper 17 (Th17) and regulatory T cells share plasticity in the expression of interleukin (IL)-17 and forkhead box P3 (FOXP3), but their mutual presence in human diseases is unclear.

METHODS

IL-17 and FOXP3 were analyzed by immunohistostaining and flow cytometry. The cytokine milieu was analyzed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

Oral squamous cell carcinoma expresses high levels of IL-1β, IL-6, and transforming growth factor (TGF)-β. A unique subset of FOXP3(+) IL-17-producing CD4(+) T cells was consistently identified in tumor-infiltrating lymphocytes from advanced stages of cancer, but not in the circulation, at a frequency of 0.5% to 5.5 % of total CD4(+) T and positively correlated with the frequency of IL-17(+)FOXP3(-) T cells. The IL-17(+)FOXP3(+) T cells express CCR6 and suppress the proliferation of autologous CD4(+) CD25(-) responder T-cells in vitro.

CONCLUSIONS

The prevalence of IL-17-producing FOXP3(+) CD4(+) tumor infiltrating lymphocytes is increased in oral squamous cell carcinoma.

FOXP3+ regulatory T cells and tumoral indoleamine 2,3-dioxygenase expression predicts the carcinogenesis of intraductal papillary mucinous neoplasms of the pancreas

BACKGROUND AND AIMS

FOXP3+ regulatory T cells (Tregs) play a central role in self-tolerance and suppress the effective antitumor immune response. A recent study revealed that indoleamine 2,3-dioxygenase (IDO)-mediated tryptophan depletion was able to affect local tumor-infiltrating lymphocytes. The aim of this study was to investigate the clinical significance of the tumor-infiltrating Tregs and tumoral IDO expression during the progression of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas.

METHODS

We investigated the prevalence and localization of FOXP3+ Tregs, CD8+ lymphocytes, and IDO expression in IPMNs by immunohistochemistry. We recruited 39 cases with IPMNs (IPMA: adenoma, n = 11; IPMB: borderline malignancy, n = 9; IPMC: noninvasive carcinoma, n = 7; I-IPMC: invasive IPMC, n = 12).

RESULTS

The prevalence of Tregs increased step by step during the carcinogenesis of IPMNs (Kruskal-Wallis test: p < 0.0001). IDO expression in the tumor was observed in 5 cases with IPMNs (IPMC, n = 1; I-IPMC, n = 4). IDO expression in the tumor was positively correlated with the prevalence of Tregs in IPMNs.

CONCLUSIONS

FOXP3+ Tregs play a role in controlling the immune surveillance against IPMNs at the premalignant stage. IDO expression in the tumor is one of the late-stage phenomena of multistage carcinogenesis of IPMNs.

Tumor-reactive CD8+ early effector T cells identified at tumor site in primary and metastatic melanoma

CD8(+) T cells at the earliest stage of effector generation have not been identified at tumor site of melanoma patients. Such early effectors, if present, should be characterized by a specific phenotype, distinct from that expressed at later stages of the antigen-induced differentiation program, by short-lived effector cells, memory precursors, and terminal effectors. Here, we show that neoplastic tissues from primary and metastatic lesions of melanoma patients contain a subset of CD8(+) T cells expressing FOXP3. CD8(+) FOXP3(+) CD25(+) T lymphocytes were found in tumor-invaded lymph nodes (TILN), s.c. metastases, and advanced primary lesions. Their frequency was significantly higher in TILN compared with tumor-free lymph nodes or with peripheral blood and in primary tumors compared with TILN. CD8(+) FOXP3(+) T cells did not express markers of regulatory [CTLA-4, CCL4, interleukin-10 (IL-10), transforming growth factor-β1], exhausted (PD-1), or senescent (CD57) CD8(+) T lymphocytes. Instead, this subset showed an antigen-experienced "EM1" phenotype (CCR7(-) CD45RA(-) CD28(+) CD27(+)) and exhibited a CD127(-), KLRG1(-), HLA-DR(+), CD38(+), T-bet(+), perforin(+) "early effector" profile predicted by current models. CD8(+) FOXP3(+) T cells produced IFN-γ on short in vitro activation, recognized autologous tumor by CD107a mobilization, and expressed Ki-67 on ex vivo analysis. In response to autologous tumor plus IL-2/IL-15, the CD8(+) FOXP3(+) T cells proliferated promptly and showed competence for differentiation (downregulation of CD27 and upregulation of T-bet). These results suggest development of early phases of antitumor immunity even in advanced melanoma. Moreover, the CD8(+) FOXP3(+) "early effector" subset may be an invaluable tool for monitoring immunity at tumor site.

Development of a nascent galectin-1 chimeric molecule for studying the role of leukocyte galectin-1 ligands and immune disease modulation

Galectin-1 (Gal-1), a β-galactoside-binding lectin, plays a profound role in modulating adaptive immune responses by altering the phenotype and fate of T cells. Experimental data showing recombinant Gal-1 (rGal-1) efficacy on T cell viability and cytokine production, nevertheless, is controversial due to the necessity of using stabilizing chemicals to help retain Gal-1 structure and function. To address this drawback, we developed a mouse Gal-1 human Ig chimera (Gal-1hFc) that did not need chemical stabilization for Gal-1 ligand recognition, apoptosis induction, and cytokine modulation in a variety of leukocyte models. At high concentrations, Gal-1hFc induced apoptosis in Gal-1 ligand(+) Th1 and Th17 cells, leukemic cells, and granulocytes from synovial fluids of patients with rheumatoid arthritis. Importantly, at low, more physiologic concentrations, Gal-1hFc retained its homodimeric form without losing functionality. Not only did Gal-1hFc-binding trigger IL-10 and Th2 cytokine expression in activated T cells, but members of the CD28 family and several other immunomodulatory molecules were upregulated. In a mouse model of contact hypersensitivity, we found that a non-Fc receptor-binding isoform of Gal-1hFc, Gal-1hFc2, alleviated T cell-dependent inflammation by increasing IL-4(+), IL-10(+), TGF-β(+), and CD25(high)/FoxP3(+) T cells, and by decreasing IFN-γ(+) and IL-17(+) T cells. Moreover, in human skin-resident T cell cultures, Gal-1hFc diminished IL-17(+) T cells and increased IL-4(+) and IL-10(+) T cells. Gal-1hFc will not only be a useful new tool for investigating the role of Gal-1 ligands in leukocyte death and cytokine stimulation, but for studying how Gal-1-Gal-1 ligand binding shapes the intensity of immune responses.

The mRNA expression of pro- and anti-inflammatory cytokines in T regulatory cells in children with type 1 diabetes

Type 1 diabetes mellitus (T1DM) is caused by the autoimmune-mediated destruction of insulin-producing beta cells in the pancreas. T regulatory cells (Tregs) represent an active mechanism of suppressing autoreactive T cells that escape central tolerance. The aim of our study was to test the hypothesis that T regulatory cells express pro- and anti-inflammatory cytokines, elements of cytotoxicity and OX40/4-1BB molecules. The examined group consisted of 50 children with T1DM. Fifty two healthy individuals (control group) were enrolled into the study. A flow cytometric analysis of T-cell subpopulations was performed using the following markers: anti-CD3, anti-CD4, anti-CD25, anti-CD127, anti-CD134 and anti-CD137. Concurrently with the flow cytometric assessment of Tregs we separated CD4+CD25+CD127dim/- cells for further mRNA analysis. mRNA levels for transcription factor FoxP3, pro- and anti-inflammatory cytokines (interferon gamma, interleukin-2, interleukin-4, interleukin-10, transforming growth factor beta1 and tumor necrosis factor alpha), activatory molecules (OX40, 4-1BB) and elements of cytotoxicity (granzyme B, perforin 1) were determined by real-time PCR technique. We found no alterations in the frequency of CD4+CD25highCD127low cells between diabetic and control children. Treg cells expressed mRNA for pro- and anti-inflammatory cytokines. Lower OX40 and higher 4-1BB mRNA but not protein levels in Treg cells in diabetic patients compared to the healthy children were noted. Our observations confirm the presence of mRNA for pro- and anti-inflammatory cytokines in CD4+CD25+CD127dim/- cells in the peripheral blood of children with T1DM. Further studies with the goal of developing new strategies to potentiate Treg function in autoimmune diseases are warranted.

Reciprocal changes of Foxp3 expression in blood and intestinal mucosa in IBD patients responding to infliximab

BACKGROUND

Immune therapies may act in inflammatory bowel diseases (IBD) by modulating regulatory T cells (Tregs). Therefore, we investigated the effect of infliximab (IFX) therapy on Forkhead box protein3 (Foxp3) T cells in blood and intestinal mucosa from Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

Forty patients with active IBD (23 CD / 17 UC) were treated with IFX 5 mg/kg intravenously at weeks 0, 2, 6, and each 8 weeks thereafter. Blood samples were obtained before every infusion and T-lymphocyte subsets were characterized by flow cytometry. Foxp3 expression in intestinal biopsies from 43 patients with active IBD (19 CD / 24 UC) before and after IFX infusion and from 6 controls were assessed by quantitative reverse-transcription polymerase chain reaction and immunohistochemistry. Plasma C-reactive protein (CRP), clinical response, and endoscopic healing data were collected in parallel.

RESULTS

IFX therapy resulted in a significant and sustained relative increase of CD4(+)CD25(+)Foxp3(+) Treg and of CD4(+)CD25(-)Foxp3(+) Treg cells in peripheral blood (both P < 0.0001 compared to baseline), particularly in responders (both P < 0.05 compared to nonresponders). The change in CRP over time inversely correlated with the increase of CD25(+)Foxp3(+) cells (P < 0.001, r = -0.39) and durable clinical response was associated with a sustained increase of circulating Foxp3(+) cells. Surprisingly, IFX therapy downregulated mucosal mRNA and protein expression of Foxp3 in UC and CD responders (both P < 0.001) but not in nonresponders.

CONCLUSIONS

IFX therapy has opposite effects in Foxp3(+) Treg cells in blood and gut mucosa, which suggests a redistribution of this important T-cell subset.

Anti-inflammatory M2 type macrophages characterize metastasized and tyrosine kinase inhibitor-treated gastrointestinal stromal tumors

We have made a detailed inventory of the immune infiltrate of gastrointestinal stromal tumors (GISTs), which originate from mesenchymal cells in the intestinal tract. These sarcomas are heavily infiltrated with macrophages and T cells, while immune cells of other lineages were much less abundant. Dissecting the functional subtypes of T cells with multicolor fluorescent microscopy revealed substantial populations of cytotoxic T cells, helper T cells and FoxP3(+) regulatory T cells. The balance of cytotoxic T cells and FoxP3(+) T cells was toward immune suppression. Analysis of the macrophage population also showed a dominance of anti-inflammatory cells, as the M2 type scavenger receptor CD163 was abundantly present. Other subsets of macrophages (CD14(+)CD163(-)) were occasionally detected. M2 type CD163(+) macrophages were associated with the number of infiltrating FoxP3(+) regulatory T cells and twice as many macrophages were found in metastatic GIST compared to primary lesions. Most metastatic GISTs had been treated with the tyrosine kinase inhibitors imatinib and sunitinib, but the high macrophage infiltrate was not related to this treatment. However, imatinib and sunitinib did induce secretion of anti-inflammatory IL-10 in macrophage cultures, indicating that treatment with these inhibitors might contribute to an immune suppressive microenvironment in GIST. Overall, our data reveal a picture of GIST as an active site of tumor-immune interaction in which suppressive mechanisms overrule potential antitumor responses. Tyrosine kinase inhibitors might promote this negative balance.

Predictive and prognostic protein biomarkers in epithelial ovarian cancer: recommendation for future studies

Epithelial ovarian cancer is the most lethal gynecological malignancy. Due to its lack of symptoms, this disease is diagnosed at an advanced stage when the cancer has already spread to secondary sites. While initial rates of response to first treatment is >80%, the overall survival rate of patients is extremely low, mainly due to development of drug resistance. To date, there are no reliable clinical factors that can properly stratify patients for suitable chemotherapy strategies. Clinical parameters such as disease stage, tumor grade and residual disease, although helpful in the management of patients after their initial surgery to establish the first line of treatment, are not efficient enough. Accordingly, reliable markers that are independent and complementary to clinical parameters are needed for a better management of these patients. For several years, efforts to identify prognostic factors have focused on molecular markers, with a large number having been investigated. This review aims to present a summary of the recent advances in the identification of molecular biomarkers in ovarian cancer patient tissues, as well as an overview of the need and importance of molecular markers for personalized medicine in ovarian cancer.

Role played by CD4+FOXP3+ regulatory T Cells in suppression of host responses to Haemophilus ducreyi during experimental infection of human volunteers

Haemophilus ducreyi causes chancroid, a genital ulcer disease. Among human volunteers, the majority of experimentally infected individuals fail to clear the infection and form pustules. Here, we investigated the role played by CD4(+)FOXP3(+) regulatory T (T(reg)) cells in the formation of pustules. In pustules, there was a significant enrichment of CD4(+)FOXP3(+) T cells, compared with that in peripheral blood. The majority of lesional FOXP3(+) T cells were CD4(+), CD25(+), CD127(lo/-), and CTLA-4(+). FOXP3(+) T cells were found throughout pustules but were most abundant at their base. Significantly fewer lesional CD4(+)FOXP3(+) T cells expressed interferon gamma, compared with lesional CD4(+)FOXP3(-) effector T cells. Depletion of CD4(+)CD25(+) T cells from the peripheral blood of infected and uninfected volunteers significantly enhanced proliferation of H. ducreyi-reactive CD4(+) T cells. Our results indicate that the population of CD4(+)CD25(+)CD127(lo/-)FOXP3(+) T(reg) cells are expanded at H. ducreyi-infected sites and that these cells may play a role in suppressing the host immune response to the bacterium.

The pathogen recognition receptor NOD2 regulates human FOXP3+ T cell survival

The expression of pathogen recognition receptors in human FOXP3+ T regulatory cells is established, yet the function of these receptors is currently obscure. In the process of studying the function of both peripheral and lamina propria FOXP3+ lymphocytes in patients with the human inflammatory bowel disease Crohn's disease, we observed a clear deficiency in the quantity of FOXP3+ lymphocytes in patients with disease-associated polymorphisms in the pathogen recognition receptor gene NOD2. Subsequently, we determined that the NOD2 ligand, muramyl dipeptide (MDP), activates NF-kappaB in primary human FOXP3+ T cells. This activation is functionally relevant, as MDP-stimulated human FOXP3+ T cells are protected from death receptor Fas-mediated apoptosis. Importantly, apoptosis protection was not evident in MDP-stimulated FOXP3+ T cells isolated from a patient with the disease-associated polymorphism. Thus, we propose that one function of pathogen recognition receptors in human T regulatory cells is the protection against death receptor-mediated apoptosis in a Fas ligand-rich environment, such as that of the inflamed intestinal subepithelial space.

Regulatory T cells in cancer

At the present time, regulatory T cells (Tregs) are an integral part of immunology but the route from discovery of "suppressive" lymphocytes in the 1980s to the current established concept of Tregs almost 20 years later has been a rollercoaster ride. Tregs are essential for maintaining self-tolerance as defects in their compartment lead to severe autoimmune diseases. This vitally important function exists alongside the detrimental effects on tumor immunosurveillance and antitumor immunity. Beginning with the identification of CD4(+)CD25(+) Tregs in 1995, the list of Treg subsets, suppressive mechanisms, and knowledge about their various origins is steadily growing. Increase in Tregs within tumors and circulation of cancer patients, observed in early studies, implied their involvement in pathogenesis and disease progression. Several mechanisms, ranging from proliferation to specific trafficking networks, have been identified to account for their systemic and/or local accumulation. Since various immunotherapeutic approaches are being utilized for cancer therapy, various strategies to overcome the antagonistic effects exerted by Tregs are being currently explored. An overview on the biology of Tregs present in cancer patients, their clinical impact, and methods for modulating them is given in this review. Despite the extensive studies on Tregs in cancer many questions still remain unanswered. Even the paradigm that Tregs generally are disadvantageous for the control of malignancies is now under scrutiny. Insight into the specific role of Tregs in different types of neoplasias is the key for targeting them in a way that is beneficial for the clinical outcome.

Disturbances in some gene expression in T regulatory cells separated from children with metabolic syndrome

The metabolic syndrome (MS) is defined as a cluster of risk factors, including abdominal obesity, dyslipidaemia, glucose intolerance and hypertension, which increase the risk for coronary heart disease. The immunological aspects of obesity and MS, including the role of T regulatory cells, have been intensively investigated. The aim of this study was to determine whether there is any disturbance in T regulatory cells number and/or function in children with MS. The percentages of T regulatory cells in the peripheral blood of children fulfilling the International Diabetes Federation criteria of the disease (n = 47) were assessed. Treg cells were also separated for further analysis of multiple genes important in their function with the use of real-time RT-PCR. We did not observe any difference in Treg percentages between study and control group but there was lower expression of some molecules including transforming growth factor-beta and interleukin-12 family members in Treg cells separated from children with MS compared to the healthy subjects. Our study is the first to report significant disturbances in some gene expression in T regulatory cells separated from children with MS. The results should be useful for further research in this field, including immunotherapeutic interventions.

Homeostasis of peripheral FoxP3(+) CD4 (+) regulatory T cells in patients with early and late stage breast cancer

FoxP3( + ) CD4( + ) regulatory T cells (Tregs) are important mediators of peripheral immune tolerance, acting via multiple mechanisms to suppress cellular immunity including antitumor responses. Although therapeutic strategies have been proposed to deplete Tregs in patients with breast cancer and other malignancies, dynamic changes in the Treg compartment as a function of stage and treatment of breast cancer remain poorly understood. Here, we evaluated peripheral blood CD4(+) T cells and FoxP3(+) CD4(+) T cells from 45 patients with early or late stage breast cancer and compared percentages, absolute counts, and Treg function to those from healthy volunteers (HV) of comparable age. Patients having completed adjuvant chemotherapy and patients with metastatic cancer exhibited significantly lower absolute CD4 counts and significantly higher percentages of FoxP3(+) CD4(+) T cells. In contrast, the absolute counts of circulating FoxP3(+) CD4(+) T cells did not differ significantly among early stage patients, late stage patients, or HV. Functionally, FoxP3(+) CD4(+) T cells from all donor groups similarly expressed CTLA-4 and failed to secrete IFN-gamma in response to stimulation. Thus, although Tregs comprise an increased percentage of circulating CD4(+) T cells in patients with metastatic breast cancer and patients in remission after completing the adjuvant chemotherapy, the systemic Treg pool, as measured by absolute counts, appears relatively constant regardless of disease stage or treatment status. Total CD4(+) T cell counts are not constant, however, suggesting that homeostatic mechanisms, or susceptibility to cytotoxic or malignant insults, fundamentally differ for regulatory and non-regulatory CD4(+) T cells.

FOXP3+ cell density in primary tumor has no prognostic impact in patients with cutaneous malignant melanoma

Regulatory T cells (Tregs) have been implicated as inhibitors of antitumor immune reactions. However, data on the relevance of their prevalence at tumor sites in influencing disease outcome are controversial. The aim of our study was to investigate the role in tumor progression and the prognostic impact of the density of lymphocytes expressing FOXP3, a transcription factor expressed predominantly by CD4(+)CD25(+) Tregs, in primary cutaneous melanoma. We examined the infiltration of FOXP3(+) cells by immunohistochemistry in tumor samples from 97 patients and evaluated in relation to patient and tumor parameters. The degree of infiltration by FOXP3(+) cells did not show correlation with the thickness of melanomas. Moreover, no associations were found with metastasis formation during the 5-year follow-up period, patient survival, or any other clinicopathologic parameters studied. These results suggest that the presence of FOXP3(+) lymphocytes in primary tumors is not of prognostic importance in human cutaneous melanoma.

A unifying microenvironment model in follicular lymphoma: outcome is predicted by programmed death-1--positive, regulatory, cytotoxic, and helper T cells and macrophages

PURPOSE

The microenvironment influences outcome in follicular lymphoma. Our hypothesis was that several immune cell subsets are important for disease outcome and their individual prognostic importance should be demonstrable in the same analysis and in competition with clinical factors.

EXPERIMENTAL DESIGN

Seventy follicular lymphoma patients with extreme clinical outcome ("poor" and "good" cases) were selected in a population-based cohort of 197. None of the 37 good-outcome patients died from lymphoma, whereas all the 33 poor-outcome patients succumbed in <or=5 years. Furthermore, the good-outcome patients were followed for a long time and needed no or little treatment. A tissue microarray was constructed from diagnostic, pretreatment biopsies. Cellular subsets were quantified after immunostaining, using computerized image analysis, separating cells inside and outside the follicles (follicular and interfollicular compartments). Flow cytometry data from the same samples were also used.

RESULTS

Independently of the Follicular Lymphoma International Prognostic Index, CD4(+) cells were associated with poor outcome and programmed death-1-positive and CD8(+) cells were associated with good outcome. The prognostic values of CD4(+) and programmed death-1-positive cells were accentuated when they were follicular and that of CD8(+) cells were accentuated when they were interfollicular. Follicular FOXP3(+) cells were associated with good outcome and interfollicular CD68(+) cells were associated with poor outcome. Additionally, high CD4/CD8 and CD4 follicular/interfollicular ratios correlated with poor outcome.

CONCLUSION

There are many important immune cell subsets in the microenvironment of follicular lymphoma. Each of these is independently associated with outcome. This is the first study showing the effect of the balance of the entire microenvironment, not only of individual subsets.

The role of regulatory T cells in cancer

There has been an explosion of literature focusing on the role of regulatory T (Treg) cells in cancer immunity. It is becoming increasingly clear that Treg cells play an active and significant role in the progression of cancer, and have an important role in suppressing tumor-specific immunity. Thus, there is a clear rationale for developing clinical strategies to diminish their regulatory influences, with the ultimate goal of augmenting antitimor immunity. Therefore, manipulation of Treg cells represent new strategies for cancer treatment. In this Review, I will summarize and review the explosive recent studies demonstrating that Treg cells are increased in patients with malignancies and restoration of antitumor immunity in mice and humans by depletion or reduction of Treg cells. In addition, I will discuss both the prognostic value of Treg cells in tumor progression in tumor-bearing hosts and the rationale for strategies for therapeutic vaccination and immunotherapeutic targeting of Treg cells with drugs and microRNA.