Mucosal but not peripheral FOXP3+ regulatory T cells are highly increased in untreated HIV infection and normalize after suppressive HAART

Recent evidence indicates that regulatory T cells (T(regs)) play an important role in HIV infection. However, although the gastrointestinal mucosa is a key compartment in HIV disease, no data on mucosal T(regs) in HIV infection are available. In this study, we compared the frequency of T(regs) in duodenal mucosa and peripheral blood (PB) of 13 treatment-naive and 13 suppressively treated HIV-infected patients with that of 6 patients with norovirus infection and 12 healthy controls. T(regs) were quantified by immunohistochemistry (CD3/FOXP3) and further characterized (CD25, CTLA-4, GITR) by immunohistochemistry, immunofluorescence, and fluorescence-activated cell sorting (FACS). Both the frequency and the absolute count of mucosal T(regs) were highly increased in untreated HIV patients but were normal in treated HIV patients. In contrast, in peripheral blood of HIV patients, the absolute number of T(regs) was not increased, and their frequency was only slightly elevated. In norovirus infection, frequency of mucosal T(regs) in the CD4+ T-cell subset was not elevated. The high increase in count and frequency of mucosal T(regs) seems to be a characteristic feature of untreated HIV infection, suggesting a significant contribution of T(regs) to the pathogenesis of HIV disease. Their role may be 2-edged: attenuating HIV-induced immune hyperactivation while suppressing the immune response to HIV and mucosal pathogens.     

Expression of GARP selectively identifies activated human FOXP3+ regulatory T cells

The molecules that define human regulatory T cells (Tregs) phenotypically and functionally remain to be fully characterized. We recently showed that activated human Tregs express mRNA for a transmembrane protein called glycoprotein A repetitions predominant (GARP, or LRRC32). Here, using a GARP-specific mAb, we demonstrate that expression of GARP on activated Tregs correlates with their suppressive capacity. However, GARP was not induced on T cells activated in the presence of TGFβ, which expressed high levels of FOXP3 and lacked suppressive function. Ectopic expression of FOXP3 in conventional T cells was also insufficient for induction of GARP expression in most donors. Functionally, silencing GARP in Tregs only moderately attenuated their suppressive activity. CD25+ T cells sorted for high GARP expression displayed more potent suppressive activity compared with CD25+GARP− cells. Remarkably, CD25+GARP− T cells expanded in culture contained 3–5 fold higher IL-17-secreting cells compared with either CD25+GARP+ or CD25−GARP− cells, suggesting that high GARP expression can potentially discriminate Tregs from those that have switched to Th17 lineage. We also determined whether GARP expression correlates with FOXP3-expressing T cells in human immunodeficiency virus (HIV) −infected subjects. A subset of HIV+ individuals with high percentages of FOXP3+ T cells did not show proportionate increase in GARP+ T cells. This finding suggests that higher FOXP3 levels observed in these HIV+ individuals is possibly due to immune activation rather than to an increase in Tregs. Our findings highlight the significance of GARP both in dissecting duality of Treg/Th17 cell differentiation and as a marker to identify bona fide Tregs during diseases with chronic immune activation.     

Antidiabetogenic MHC class II promotes the differentiation of MHC-promiscuous autoreactive T cells into FOXP3+ regulatory T cells

Polymorphisms in MHC class II molecules, in particular around β-chain position-57 (β57), afford susceptibility/resistance to multiple autoimmune diseases, including type 1 diabetes, through obscure mechanisms. Here, we show that the antidiabetogenic MHC class II molecule I-A^b affords diabetes resistance by promoting the differentiation of MHC-promiscuous autoreactive CD4⁺ T cells into disease-suppressing natural regulatory T cells, in a β56–67-regulated manner. We compared the tolerogenic and antidiabetogenic properties of CD11c promoter-driven transgenes encoding I-A^b or a form of I-A^b carrying residues 56–67 of I-Aβ^g7 (I-A^b-g7) in wild-type nonobese diabetic (NOD) mice, as well as NOD mice coexpressing a diabetogenic and I-A^g7–restricted, but MHC-promiscuous T-cell receptor (4.1). Both I-A transgenes protected NOD and 4.1-NOD mice from diabetes. However, whereas I-A^b induced 4.1-CD4⁺ thymocyte deletion and 4.1-CD4⁺Foxp3⁺ regulatory T-cell development, I-A^b-g7 promoted 4.1-CD4⁺Foxp3⁺ Treg development without inducing clonal deletion. Furthermore, non–T-cell receptor transgenic NOD.CD11cP-I-A^b and NOD.CD11cP-IA^b-g7 mice both exported regulatory T cells with superior antidiabetogenic properties than wild-type NOD mice. We propose that I-A^b, and possibly other protective MHC class II molecules, afford disease resistance by engaging a naturally occurring constellation of MHC-promiscuous autoreactive T-cell clonotypes, promoting their deviation into autoregulatory T cells.     

The number of tumour-infiltrating TIA-1+ cytotoxic T cells but not FOXP3+ regulatory T cells predicts outcome in diffuse large B-cell lymphoma

The prognostic significance of tumour-infiltrating lymphocytes (TILs) in patients with diffuse large B-cell lymphoma (DLBCL) remains controversial. Furthermore, the possible impact of regulatory T cells (T(regs)) on survival in DLBCL is still unknown. We performed a retrospective study on the immunohistochemical expression of cytotoxic cells and T(regs), and their correlation with survival in 195 DLBCL patients. Patients with a small number of cytotoxic T-cell intracytoplasmic antigen-1 (TIA-1)+ T cells (< or =260 cells/mm(2) tumour area; n = 52) had significantly better outcome than patients with a large number (>260 cells/mm(2); n = 143); progression-free survival (PFS) at 5 years was 67% vs. 50% (P = 0.03) and overall survival (OS) was 73% vs. 57% (P = 0.03). In multivariate analysis, the low TIA-1+ group still had a better PFS (relative risk 0.75, 95% confidence interval 0.31-0.99; P = 0.05). The number of forkhead box protein 3 (FOXP3)+ T(regs) had no influence on PFS (P = 0.89) or OS (P = 0.75). These results suggest that immunohistochemical analysis of cytotoxic T cells at time of diagnosis could provide additional prognostic information. The lack of correlation between the number of FOXP3+ cells and survival could possibly indicate that tumour-infiltrating T(regs) are of less clinical importance in DLBCL. However, these findings need to be explored in functional studies.     

FOXP3在系统性红斑狼疮患者CD4+CD25+调节性T细胞中的表达

目的 研究FOXP3在系统性红斑狼疮(SLE)患者的CD4+CD25调节性T细胞中的表达.方法 流式细胞仪检测CD4+CD25+,CD4+CD25bright T细胞中FOXP3蛋白的表达.利用免疫磁珠细胞分选法(MACS)分选出CD4+CD25+调节性T细胞,实时定量聚合酶链反应(real-time PCR)检测FOXP3基因的表达.结果 以FOXP3作为CD4+CD25+调节性T细胞的主要识别标志,初发、活动性SLE患者的CD4+CD25+ FOXP3+调节性T细胞在CD4+T细胞中的比例高于健康对照组[(9.1±0.7)%VS(4.8±0.4)%,P＜0.01],与SLEDAI评分呈明显正相关.CD4+CD25+调节性T细胞中FOXP3在蛋白和mRNA水平上的表达,SLE患者与健康对照组相比无明显差异.结论 SLE患者CD4+CD25+调节性T细胞中FOXP3的表达无明显异常,其CD4+T细胞中调节性T细胞的比例高于健康对照组.提示研究这类细胞在SLE发病中的作用应更关注其功能.     

Expression of CD4+ forkhead box P3 (FOXP3)+ regulatory T cells in inflammatory bowel disease

OBJECTIVE: Forkhead box P3 (FOXP3) plays an important role in the development and function of CD4⁺ regulatory T (Treg) cells. In this study the percentage of CD4⁺ FOXP3⁺ Treg cells in peripheral blood mononuclear cells (PBMC) and the frequency of Treg cells in the colonic mucosa of patients with inflammatory bowel disease (IBD) were investigated. METHODS: The percentage of CD4⁺FOXP3⁺ Treg cells in PBMC was analyzed by flow cytometry. Immunohistochemistry was used to examine the FOXP3⁺ cells in the inflamed mucosa. Real‐time polymerase chain reaction and Western blot were used to detect the expressions of FOXP3 mRNA and protein in PBMC and mucosal biopsy specimens of IBD patients, respectively. RESULTS: Together with the decrease of percentage of Treg cells in PBMC, we found that the frequency of Treg cells increased significantly in inflamed mucosa of active or inactive Crohn's disease (CD) and ulcerative colitis (UC). The expressions of FOXP3 mRNA and protein increased in inflamed mucosa when compared with those in healthy controls, especially the FOXP3 mRNA in patients with active CD or UC. Interestingly, the expression of FOXP3 protein in active UC was higher than that in active CD. CONCLUSIONS: There was a decrease of CD4⁺FOXP3⁺ Treg cells in peripheral blood and an accumulation of Treg cells in inflamed mucosa. These data suggested that the suppressive function of Treg cells may be partially inhibited and this could be an important factor in the recurrence of disease, especially in UC.     

High numbers of tumor-infiltrating FOXP3-positive regulatory T cells are associated with improved overall survival in follicular lymphoma

The tumor microenvironment plays an important role in the biologic behavior of follicular lymphoma (FL), but the specific cell subsets involved in this regulation are unknown. To determine the impact of FOXP3-positive regulatory T cells (Tregs) in the progression and outcome of FL patients, we examined samples from 97 patients at diagnosis and 37 at first relapse with an anti-FOXP3 monoclonal antibody. Tregs were quantified using computerized image analysis. The median overall survival (OS) of the series was 9.9 years, and the FL International Prognostic Index (FLIPI) was prognostically significant. The median Treg percentage at diagnosis was 10.5%. Overall, 49 patients had more than 10% Tregs, 30 between 5% to 10%, and 19 less than 5%, with a 5-year OS of 80%, 74%, and 50%, respectively (P = .001). Patients with very low numbers of Tregs (< 5%) presented more frequently with refractory disease (P = .007). The prognostic significance of Treg numbers was independent of the FLIPI. Seven transformed diffuse large B-cell lymphomas (DLBCLs) had lower Treg percentages (mean: 3.3%) than FL grades 1,2 (mean: 12.1%) or 3 (mean: 9%) (P < .02). In conclusion, high Treg numbers predict improved survival of FL patients, while a marked reduction in Tregs is observed on transformation to DLBCL.     

Foxp3+ regulatory T cells in antiretroviral-naive HIV patients

We characterized regulatory T cells from antiretroviral-naive HIV patients by flow cytometry. The proportion of CD4 cells positive for CD25 and Foxp3 was increased, mainly in those with CD4 cell counts less than 200 cells/microl. The total number of Foxp3-positive cells correlated with the CD4 cell count. Further studies are needed on whether Foxp3-positive cell numbers or function explain the susceptibility to autoimmune and inflammatory diseases seen in some patients with advanced HIV.     

供体CD+4CD+25T细胞及调控基因FOXP3在急性移植物抗宿主病中的作用

目的 探讨供体CD+4CD+25T细胞亚群、FOXP3调控基因的表达与受者移植物抗宿主病(GVHD)的相关性.方法 (1)30例异基因造血干细胞移植(allo-HSCT),采用免疫荧光标记和流式细胞术检测并比较供体粒细胞集落刺激因子(G-CSF)动员前外周血、动员后采集物CD+4CD+25T细胞亚群比例,随访异基因移植后GVHD的发生率和严重程度.(2)应用RT-PCR技术检测供体FOXP3基因表达情况,分析其与GVHD、疾病复发的相关性.结果 (1)所有患者均获造血重建,粒细胞绝对数(ANC)≥0.5×109/L的中位时间为14(12～15)d,PLT≥20×109/L为18(15～25)d.30例allo-HSCT,中位随访时间12.8(8～16)个月,Ⅰ～Ⅳ度急性GVHD分别为3、4、3、5例.慢性GVHD 6例.(2)供体G-CSF动员前外周血、动员后采集物CD+4CD+25T细胞亚群分别为(2.67±0.38)%、(5.01±1.33)%,两者相比差异无统计学意义(P＞0.05).(3)移植后无急性GVHD组、Ⅰ～Ⅱ度急性GVHD组、Ⅲ～Ⅳ度急性GVHD组供体CD+4CD+25T细胞亚群分别为(5.05±1.34)%、(4.17±1.73)%、(1.98±1.10)%.其中Ⅰ～Ⅱ度急性GVHD组与Ⅲ～Ⅳ度急性GVHD组相比差异有统计学意义(P=0.04),无急性GVHD组与Ⅲ～Ⅳ度急性GVHD组相比差异有统计学意义(P=0.002).(4)30例allo-HSCT,7例FOXP3基因表达阳性,5/7例移植后无急性GVHD,其中3例移植后复发,另2/7例移植后Ⅰ度急性GVHD,Ⅱ～Ⅳ度急性GVHD患者FOXP3均不表达.结论 (1)供体CD+4CD+25T细胞亚群比例与受者急性GVHD的发生具有一定的相关性,提高供体CD+4CD+25T细胞数量有望减低移植后急性GVHD发生率.(2)供体移植物FOXP3基因表达阳性,与移植后有无严重急性GVHD发生存在一定相关性.