Reduction of forkhead box P3 levels in CD4+CD25high T cells in patients with new-onset systemic lupus erythematosus

The aim of this study was to quantify and evaluate the forkhead box P3 (FoxP3) expression regulatory T cells in new-onset systemic lupus erythematosus (SLE) patients before and after treatment. Forty-four newly diagnosed and untreated SLE patients, including 24 with active disease (SLEDAI > or = 10) and 20 with inactive disease (SLEDAI < 5), were enrolled in this study. Twenty-one age- and sex-matched healthy volunteers were also included as controls. Peripheral blood samples were collected and mononuclear cells isolated. The expression of CD25 and FoxP3 in CD4(+) T cells were analysed with flow cytometry. CD4(+)CD25(+) (3.95-13.04%) and CD4(+)CD25(high) (0.04-1.34%) T cells in peripheral blood in untreated patients with new-onset active lupus were significantly lower than that in the patients with inactive lupus (7.27-24.48%, P < 0.05 and 0.14-3.07% P < 0.01 respectively) and that in healthy controls (5.84-14.84%, P < 0.05). Interestingly, the decrease in CD4(+)CD25(high) T cells was restored significantly in patients with active lupus after corticosteroid treatment. There was, however, a significantly higher percentage of CD4(+)FoxP3(+) T cells in patients with active (5.30-23.00%) and inactive (7.46-17.38%) new-onset lupus patients compared with healthy control subjects (2.51-12.94%) (P < 0.01). Intriguingly, CD25 expression in CD4(+)FoxP3(+) T cells in patients with active lupus (25.24-62.47%) was significantly lower than that in those patients with inactive lupus (30.35-75.25%, P < 0.05) and healthy controls (54.83-86.38%, P < 0.01). Most strikingly, the levels of FoxP3 expression determined by mean fluorescence intensity in CD4(+)CD25(high) cells in patients with active SLE were significantly down-regulated compared with healthy subjects (130 +/- 22 versus 162 +/- 21, P = 0.012). CD4(+)CD25(high) T cells are low in new-onset patients with active SLE and restored after treatment. Despite that the percentage of CD4(+)FoxP3(+) T cells appear high, the levels of FoxP3 expression in CD4(+)CD25(high) T cells are down-regulated in untreated lupus patients. There is a disproportional expression between CD25(high) and FoxP3(+) in new-onset patients with active SLE.     

Frequencies and role of regulatory T cells in patients with (pre)malignant cervical neoplasia

Oncogenic human papillomavirus (HPV)-infection is crucial for developing cervical cancer and its precursor lesions [cervical intraepithelial neoplasia (CIN)]. Regulatory T cells (T(regs)) might be involved in the failure of the immune system to control the development of HPV-induced cancer. We investigated frequencies, phenotype and activity of T(regs) in patients with cervical neoplasia. CIN and cervical cancer patients showed increased CD4(+)/CD25(high) T cell frequencies in peripheral blood and CD4(+) T cell fraction. These CD4(+)/CD25(high) T cells represent T(regs) as demonstrated by their low proliferation rate, low interferon (IFN)-gamma/interleukin (IL)-10 ratio, high expression of CD45RO, GITR, CTLA-4, forkhead box P3 (FoxP3) and low CD45RA expression. Moreover, in HPV16(+) cervical cancer patients, in-vitro depletion of CD25(+) T cells resulted in increased IFN-gamma T cell responses against HPV16 E6- and E7 peptides. Thus, increased frequencies of T(regs) in cervical cancer patients may indeed suppress HPV-specific immunity. Longitudinal analysis of CD4(+)/CD25(high) T cell frequencies in patients showed a modest decline 1 year after curative surgery or chemoradiation. This study demonstrates increased frequencies and suppressive activity of T(regs) in cervical cancer. These results imply that T(regs) may suppress the immune control of cervical neoplasia and furthermore that suppression of immunity by T(regs) will be another hurdle to overcome in therapeutic immunization strategies against cervical neoplasia.     

Increase of circulating CD4+CD25+ T cells in myasthenia gravis patients with stability and thymectomy

BACKGROUND: CD4(+)CD25(+) regulatory T cells are key controllers of peripheral immunological self-tolerance and suppress various autoimmune diseases in animal models, but few studies have been done to define their roles in myasthenia gravis (MG) so far. OBJECTIVE: To investigate frequencies and dynamic changes of blood CD4(+)CD25(+) T cells from MG patients. METHODS: The peripheral blood CD4(+)CD25(+) T cells of 29 MG patients and 23 healthy controls were detected by three-color flow cytometry. RESULTS: Myasthenic patients with symptomatically uncontrollable disease showed slightly lower percentages of CD4(+)CD25(+) T cells (mean = 3.79 +/- 1.40%; P = 0.12), whereas MG patients with clinically stable disease had significantly increased CD4(+)CD25(+) T cells (mean = 8.45 +/- 1.96%, P = 0.0001), as compared with healthy controls (mean = 4.53 +/- 0.96%). In addition, thymectomized MG patients had significantly higher percentages of CD4(+)CD25(+) T cells (mean = 8.44 +/- 2.39%), as compared with both non-thymectomized MG patients (mean = 5.88 +/- 2.89%, P = 0.038) and healthy controls (P = 0.003). CONCLUSIONS: Our observations indicate that increased percentages of CD4(+)CD25(+) T cells in MG patients may be related to disease stability and that thymectomy in patients with MG resulted in augmented CD4(+)CD25(+) T cells.     

The different effects of indirubin on effector and CD4+CD25+ regulatory T cells in mice: potential implication for the treatment of autoimmune diseases

CD4(+)CD25(+) regulatory T (Treg) cells play an essential role in the induction and maintenance of peripheral self-tolerance. Indirubin, a traditional Chinese medicine, was clinically used in the treatment of chronic myelocytic leukemia as well as some autoimmune diseases, including Alzheimer's disease, diabetes, and so on. The effects of indirubin on CD4(+)CD25(+)Treg cells, which play a critical role in controlling autoimmunity, have not been addressed. In the present study, we observed the cell levels, phenotypes, and immunoregulatory function of CD4(+)CD25(+)Treg cells in indirubin-treated mice. Treatment with indirubin significantly enhanced the ratios of CD4(+)CD25(+)Treg cells or CD4(+)CD25(+)Foxp3(+)Treg cells to CD4(+)T cells in peripheral blood, lymph nodes, and spleens (P < 0.01 compared with control mice). CD4(+)CD25(+)Foxp3(+)Treg cells to CD4 single positive cells in the thymi of indirubin-treated mice were significantly higher than those in control mice. Furthermore, splenic CD4(+)CD25(+)Treg cells in indirubin-treated mice showed immunosuppressive ability on the immune response of T effector cells to alloantigens or mitogen as efficiently as the control CD4(+)CD25(+)Treg cells in vitro. The present studies indicate that CD4(+)CD25(+)Treg cells are more resistant to indirubin than effector T cells in vivo. The selectively enhanced CD4(+)CD25(+)Treg cell levels by indirubin made host to be more favorable for immune tolerance induction, which opened one possibility for indirubin to treat autoimmune diseases.     

CD5 plays an inhibitory role in the suppressive function of murine CD4(+) CD25(+) T(reg) cells

A subset of CD4(+) T cells, the CD4(+) CD25(+) regulatory T (T(reg)) cells in the lymphoid organs and peripheral blood are known to possess suppressive function. Previous in vitro and in vivo studies have indicated that T cell receptor (TCR) signal is required for development of such 'natural regulatory (T(reg)) cells' and for activation of the effector function of CD4(+) CD25(+) regulatory T cells. CD5 is a cell surface molecule present on all T cells and a subtype of B lymphocytes, the B-1 cells, primarily localized to coelomic cavities, Peyer's patches, tonsils and spleen. CD5 acts as a negative regulator of T cell and B cell signaling via recruitment of SHP-1. Here, we demonstrate that T(reg) cells obtained from CD5(-/-) mice are more potent than those from wild type mice in suppressing the in vitro cell proliferation of anti-CD3 stimulated CD4(+) CD25(-) responder T cells. This phenomenon was cell contact and GITR dependent. Lack of CD5 expression on T(reg) cells (from spleen, lymph node and thymus) did not affect the intracellular levels of Foxp3. However, CD5(-/-) T(reg) thymocytes were able to elicit a higher Ca(2+) response to TCR + co-stimulatory signals than the wild type cells. CD5(-/-) mice expressed more Foxp3 mRNA in the colon than wild type mice, and additionally, the severity of the dextran sulfate sodium (DSS)-induced colitis in CD5(-/-) mice was less than the wild type strain. We suggest that manipulation of CD5 expression or the downstream signaling components of CD4(+) CD25(+) T(reg) cells as a potential strategy for therapeutic intervention in cases of auto-immune disorders.     

Generation and function of immunosuppressive human and murine CD8+ T cells by transforming growth factor-β and retinoic acid

The intestinal immune system is constantly challenged by foreign antigens and commensal bacteria. Therefore, proper control of the intestinal microenvironment is required. One important arm of this regulatory network consists of regulatory T cells. In contrast to CD4(+) Foxp3(+) regulatory T cells, which have been well characterized, immunomodulatory CD8(+) T cells that express Foxp3 are less well defined in terms of their generation and function. Failures of these regulatory mechanisms contribute to the development of inflammatory bowel disease. In this study we demonstrate that the frequency of CD8(+) Foxp3(+) T cells is reduced in the peripheral blood of patients with ulcerative colitis. As these cells might play a currently underestimated role in the maintenance of intestinal homeostasis, we have investigated human and murine CD8(+) Foxp3(+) T cells generated by stimulating naive CD8(+) T cells in the presence of transforming growth factor-β and retinoic acid, mediators that are abundantly produced in the intestinal mucosa. These CD8(+) Foxp3(+) fully competent regulatory T cells show strong expression of regulatory molecules CD25, Gpr83 and CTLA-4 and exhibit cell-cell contact-dependent immunosuppressive activity in vitro. Our study illustrates a previously unappreciated critical role of CD8(+) Foxp3(+) T cells in controlling potentially dangerous T cells and in the maintenance of intestinal homeostasis.     

IL-10 is involved in the suppression of experimental autoimmune encephalomyelitis by CD25+CD4+ regulatory T cells

CD25(+)CD4(+) regulatory T cells inhibit the activation of autoreactive T cells in vitro and in vivo, and suppress organ-specific autoimmune diseases. The mechanism of CD25(+)CD4(+) T cells in the regulation of experimental autoimmune encephalomyelitis (EAE) is poorly understood. To assess the role of CD25(+)CD4(+) T cells in EAE, SJL mice were immunized with myelin proteolipid protein (PLP)(139-151) to develop EAE and were treated with anti-CD25 mAb. Treatment with anti-CD25 antibody following immunization resulted in a significant enhancement of EAE disease severity and mortality. There was increased inflammation in the central nervous system (CNS) of anti-CD25 mAb-treated mice. Anti-CD25 antibody treatment caused a decrease in the percentage of CD25(+)CD4(+) T cells in blood, peripheral lymph node (LN) and spleen associated with increased production of IFN-gamma and a decrease in IL-10 production by LN cells stimulated with PLP(130-151) in vitro. In addition, transfer of CD25(+)CD4(+) regulatory T cells from naive SJL mice decreased the severity of active EAE. In vitro, anti-CD3-stimulated CD25(+)CD4(+) T cells from naive SJL mice secreted IL-10 and IL-10 soluble receptor (sR) partially reversed the in vitro suppressive activity of CD25(+)CD4(+) T cells. CD25(+)CD4(+) T cells from IL-10-deficient mice were unable to suppress active EAE. These findings demonstrate that CD25(+)CD4(+) T cells suppress pathogenic autoreactive T cells in actively induced EAE and suggest they may play an important natural regulatory function in controlling CNS autoimmune disease through a mechanism that involves IL-10.     

Induction and maintenance of self tolerance: the role of CD4+CD25+ regulatory T cells

The immune system responds vigorously to invading pathogens (non-self, foreign), while remaining unresponsive (tolerant) to the body's own components and circulating constituents (self). This indifference to self components is a result of finely orchestrated events of thymic negative selection (central tolerance) of developing T cells that are autoaggressive combined with those operative in the periphery (peripheral tolerance) to control the activity of potentially autoreactive T cells that escaped thymic tolerance. Recently, autoimmune regulator expressed in the thymus has been identified as a critical mediator of central tolerance towards tissue-specific antigens. In the periphery, a variety of regulatory T cells are involved in effecting tolerance. There is immense interest and excitement about the newly identified subset of CD4(+)CD25(+) T cells. This is a unique subset of CD4(+) T cells that bear CD25 (IL-2Ralpha chain) on the cell surface in the na?ve state and express FoxP3 as a unique marker. These cells suppress the activity of autoreactive effector T cells primarily via cell-cell contact. The deficiency and/or altered function of CD4(+)CD25(+) T cells is associated with autoimmunity. Mice deficient in FoxP3 (scurfy mice) bear an autoimmune phenotype, and human males with mutations in the corresponding gene express the phenotype of wide-spread autoimmunity, the immune dysregulation, polyendocrinopathy and enteropathy, and X-linked syndrome. In vitro expansion of antigen-specific CD4(+)CD25(+) T cells and their adoptive transfer into patients suffering from autoimmunity is emerging as a promising new therapeutic approach for these debilitating disorders.     

Schistosoma japonicum egg antigens stimulate CD4 CD25 T cells and modulate airway inflammation in a murine model of asthma

A number of epidemiological and clinical studies have suggested an inverse association between allergy and helminth infection, such as Schistosomiasis. Therefore, we hypothesize that Schistosoma japonicum egg antigens, a type of native antigen, can induce production of CD4(+) CD25(+) T cells with regulatory activity, modulating airway inflammation and inhibiting asthma development. The frequency of CD4(+) CD25(+) T cells was determined by flow cytometry for mice treated with ovalbumin (OVA), CD25(+) depletion/OVA, schistosome egg antigens, schistosome egg antigens/OVA and for control mice. The ability of CD25(+) T cells from these mice to suppress T-cell proliferation and cytokine production was investigated both in vivo and in vitro. Results showed that the CD4(+) CD25(+) T cells of OVA-treated mice exhibited impaired control of dysregulated mucosal T helper 2 responses compared to the controls (P < 0.05). Depletion of CD25(+) cells accelerated OVA-induced airway inflammation and increased the expression of interleukin (IL)-5 and IL-4. Treatment with schistosome egg antigens increased the number and suppressive activity of CD4(+) CD25(+) T cells, which made IL-10, but little IL-4. In a murine model of asthma, S. japonicum egg antigens decreased the expression of Th2 cytokines, relieved antigen-induced airway inflammation, and inhibited asthma development. Thus, we provided evidence that S. japonicum egg antigens induced the production of CD4(+) CD25(+) T cells, resulting in constitutive immunosuppressive activity and inhibition of asthma development. These results reveal a novel form of protection against asthma and suggest a mechanistic explanation for the protective effect of helminth infection on the development of allergy.     

Inverse correlation between CD4+ regulatory T-cell population and autoantibody levels in paediatric patients with systemic lupus erythematosus

CD4(+) CD25(+) regulatory T cells (Tregs) are critical in maintaining self-tolerance and preventing organ-specific autoimmunity. Their role in paediatric systemic lupus erythematosus (SLE), an autoimmune disease characterized by inappropriate regulation of hyperactivated B and T cells, has not been clearly defined. Using flow cytometry to determine cell populations and real-time polymerase chain reaction to assay mRNA expression for FOXP3, CTLA-4, and GITR, we characterized CD4(+) CD25(+) T cells in paediatric SLE patients and healthy subjects. The frequency of CD4(+) CD25(+) Tregs was significantly decreased in patients with active SLE compared with patients with inactive SLE and with controls (7.27% +/- 2.50%, 9.59% +/- 2.80% and 9.78% +/- 2.11%, respectively; P = 0.027 and P < 0.001, respectively), and was inversely correlated with disease activity, as assessed with the Systemic Lupus Erythematosus Disease Activity Index 2000 scores (r = -0.59, P = 0.001) and serum anti-double-stranded DNA levels (r = -0.65, P < 0.001). Our preliminary investigations found elevated surface expression of GITR in CD4(+) CD25(+) T cells, elevated mRNA expression of CTLA-4 in CD4(+) T cells and higher amounts of mRNA expression for FOXP3 in CD4(+) cells in patients with active SLE compared with patients with inactive disease and controls. We demonstrated reduced CD4(+) CD25(+) Treg levels were inversely correlated with disease activity, indicating a defective Treg population in paediatric SLE patients. The differences in the expression of FOXP3, CTLA-4 and GITR imply the possible role of CD4(+) Tregs in the pathogenesis of SLE.     

Age-related changes in the occurrence and characteristics of thymic CD4(+) CD25(+) T cells in mice

Natural regulatory CD4(+) CD25(+) T cells play an important role in preventing autoimmunity by maintaining self-tolerance. They express CD25 constitutively and are produced in the thymus as a functionally mature T-cell population. Changes in the potential of these cells to regulate the activity of conventional effector lymphocytes may contribute to an increased susceptibility to infection, cancer and age-associated autoimmune diseases. In this study we demonstrated that the thymi of aged mice are populated by a higher percentage of CD4(+) CD25(+) thymocytes than in young animals. The expression of several surface markers (CD69, CD5, CD28, CTLA-4, CD122, FOXP3), usually used to characterize the phenotype of CD4(+) CD25(+) T regulatory cells, was compared between young and aged mice. We also examined the ability of sorted thymus-deriving regulatory T cells of young and aged BALB/c mice to inhibit the proliferation of lymph node lymphocytes activated in vitro. Natural regulatory T cells isolated from the thymi of young mice suppress the proliferation of responder lymph node cells. We demonstrated that thymus-deriving CD4(+) CD25(+) T cells of old mice maintain their potential to suppress the proliferation of activated responder lymphocytes of young mice. However, their potential to inhibit the proliferation of old responder T cells is abrogated. Differences in the occurrence and activity of CD4(+) CD25(+) thymocytes between young and old animals are discussed in relation to the expression of these surface markers.     

Quantitative and qualitative deficiencies of regulatory T cells in patients with systemic lupus erythematosus (SLE)

The objective of the study was that the regulatory T cells (Treg) that specialize in the suppression of immune responses might be critically involved in the pathogenesis of autoimmune disease. As for systemic lupus erythematosus (SLE), however, published data concerning Treg phenotype and function are partly conflicting. We therefore performed quantitative and qualitative analyses of naturally occurring CD4(+)CD25(+) Treg from SLE patients as compared with healthy controls (HC) in order to further elucidate the role of Treg in this systemic autoimmune disease. The phenotype of peripheral blood CD4(+)CD25(+) Treg was determined by flow cytometry (FACS) in SLE patients and HC. Treg were isolated from SLE patients and HC and their functional capacity was analyzed in suppression assays. Phenotypic and functional data were correlated with clinical data. Decreased proportions of CD4(+) Treg with high-level expression of CD25 (CD4(+)CD25(hi)) were observed in active and inactive SLE patients (0.96 +/- 0.08 and 1.17 +/- 0.08%, respectively) as compared with HC (2 +/- 0.1%). In contrast to HC, Treg from SLE patients displayed an activated phenotype as determined by the expression of CD69, CD71 and HLA-DR. The suppressive capacity of isolated Treg from SLE patients, however, was significantly reduced as compared with HC. Proportions of CD4(+)CD25(hi) T cells and the suppressive capacity of Treg were inversely correlated with the clinical disease activity in SLE patients. Our data describe quantitative and qualitative defects of Treg in SLE patients. These deficiencies might contribute to the breakdown of self-tolerance and the development of the autoimmune response in SLE patients.     

Neonatal Autoimmune Disease: Influence of CD4+ CD25+ Regulatory T Cells

Although previous studies have emphasized the tolerogenic property of murine neonatal immune system, recent studies indicate that neonatal mice are prone to autoimmune disease. This chapter will summarize the evidence for neonatal propensity to autoimmune ovarian disease (AOD) and describe the new finding that autoantibody can trigger a T cell–dependent autoimmune disease in neonatal but not adult mice. Based on depletion or addition of the CD4⁺CD25⁺ T cells, disease resistance of older mice is explicable by the emergence of CD4⁺CD25⁺ regulatory T-cell function after day 5, whereas disease susceptibility is associated with resistance to regulation by CD4⁺CD25⁺ T cells.     

Dendritic cells partially abrogate the regulatory activity of CD4+CD25+ T cells present in the human peripheral blood

The factors that influence the functionality of human CD4(+)CD25(+) regulatory T cells are not well understood. We sought to characterize the effects of dendritic cells (DCs) on the in vitro regulatory activity of CD4(+)CD25(+) T cells obtained from peripheral blood of healthy human donors. Flow cytometry showed that a higher proportion of CD4(+)CD25(+(High)) T cells expressed surface glucocorticoid-induced tumor necrosis factor receptor family-related protein (GITR) and CTL-associated antigen 4 than CD4(+)CD25(-) or CD4(+)CD25(+(Med-low)) T cells. Intracellular Foxp3 was equivalently expressed on CD4(+)CD25(+(All)), CD4(+)CD25(+(High)), CD4(+)CD25(+(Med-low)) and CD4(+)CD25(-) T cell populations, irrespective of GITR and CTL-associated antigen 4 expression. CD4(+)CD25(+) T cells were isolated and then cultured in vitro with CD4(+)CD25(-) responder T cells and stimulated with anti-CD3 antibodies, and immature dendritic cells (iDCs), mature dendritic cells (mDCs), PBMCs or PBMCs plus anti-CD28 antibodies to provide co-stimulation. In addition, secretion of the T(h)1 cytokine IFN-gamma, IL-2 and the immunoregulatory cytokines, IL-10 and transforming growth factor (TGF)-beta, were also assessed in these cultures. We found that iDCs and mDCs were capable of reversing the suppression of proliferation mediated by CD4(+)CD25(+) regulatory T cells. However, the reversal of suppression by DCs was not dependent upon the increase of IFN-gamma and IL-2 production or inhibition of IL-10 and/or TGF-beta production. Therefore, DCs are able to reverse the suppressive effect of regulatory T cells independent of cytokine production. These results suggest for the first time that human DCs possess unique abilities which allow them to influence the functions of regulatory T cells in order to provide fine-tuning in the regulation of T cell responses.     

Induction of CD56+ T cells after prolonged activation of T cells in vitro: a possible mechanism for CD4+ T-cell depletion in acquired immune deficiency syndrome patients

The pathogenic mechanisms responsible for depletion of CD4(+) T cells in aquired immune deficiency syndrome (AIDS) are not fully understood. Systemic immune activation mediated by persistent infection of human immunodeficiency virus (HIV) seems to be one of the predictors of disease progression. We predicted that certain lymphocytes responsible for CD4(+) T-cell depletion could be induced in patients during prolonged activation of lymphocytes. Therefore, we have established an in vitro long-term culture system for peripheral blood mononuclear cells with PHA-P stimulation and Herpesvirus saimiri infection, and examined what types of cells having strong cytotoxic activity to be emerged under the activated conditions. We observed that percentage of CD56(+) T cells was gradually increased in cultures from 30 days after stimulation and exhibited a cytotoxic activity against both autologous and allogeneic targets. Interestingly, HIV-1 infection enhanced the susceptibility of CD4(+) T cells to their cytotoxic effectors, and CD4(+) T cells from HIV-1-infected individuals showed decreased survival rate in the presence of autologous CD56(+) T cells. These findings raised the possibility that induction of autoreactive CD56(+) T cells in consequence of immune activation might be contributed to the depletion of CD4(+) T cells in HIV-1-infected patients.     

Phenotypic characterization of regulatory CD4+CD25+ T cells in rats

CD25 has become widely used as a marker for a subset of regulatory CD4(+) T cells present in the thymus and periphery of mice, rats and humans. However, CD25 is also expressed on conventionally activated T cells that are not regulatory and not all peripheral regulatory T cells express CD25. The identification of a stable and unique marker for regulatory T cells would therefore be valuable. This study provides a detailed account of the phenotype of CD4(+)CD25(+) regulatory T cells in rats. In the thymus, CD4(+)CD8(-)CD25(+) cells were found to have a more mature phenotype than the corresponding CD4(+)CD8(-)CD25(-) cells with respect to expression of Thy1 (CD90), CD53 and CD44, suggesting that CD25 expression, and perhaps commitment to regulatory function, might be a late event in thymocyte development. CD4(+)CD25(+) cells in both the thymus and periphery were found to have enriched and heterogeneous expression of activation markers such as OX40 (CD134) and OX48 (an antibody determined in this study to be specific for CD86). CD4(+)CD25(+) T cells were also found to have enriched expression of CD80, at both the mRNA and protein level. However, functional studies in vitro and in vivo showed that neither OX40 or CD86 were useful markers for the further subdivision of regulatory T cells. Our studies indicate that, at present, CD25 remains the most useful marker to enrich for regulatory CD4(+) T cells in rats and no further subdivision of the regulatory component of CD4(+)CD25(-)CD45RC(low) T cells has yet been achieved.     

Circulating CD4+CD25+ T Regulatory Cells Are Not Altered in Multiple Sclerosis and Unaffected by Disease-Modulating Drugs

Experimental animal models for autoimmunity have demonstrated the existence and crucial role of CD4(+)CD25(+) T regulatory (Tr) cells in suppressing autoreactive T cells and promoting peripheral tolerance. Recent in vitro functional studies showed that Tr cells are enriched in the CD25(high) cell population among CD4(+) T cells, and that they totally inhibit proliferation and cytokine secretion by CD4(+) T cells. It is not yet known if circulating Tr cells are involved in multiple sclerosis (MS). This study was done firstly to determine whether alterations of the CD4 (+) CD25(high) T cells occur in MS, examining their frequencies. As it was reported that the suppressive activity of CD4(+)CD25(+) Tr cells is mainly through cell surface contact pathway, we secondly analyzed the expression of the functionally important cell surface molecules of CD4(+)CD25(high) Tr cells. Two- or three-colour flow cytometry was used to identify and quantify CD4(+)CD25(+) Tr cells and CD4(+)CD25(high) Tr cells among blood CD4(+) T cells in MS patients without treatment vs. patients treated with either interferon-beta (IFN-beta) or glatiramer acetate (GA) or IFN-beta + GA in combination vs. healthy controls (HC). Expression of functionally important surface molecules CD45RO, CD69, CD95, HLA-DR, and intracellular CTLA-4 and IL-10 production by CD4(+)CD25(high) Tr cells were investigated. CD4(+)CD25(+) T cells constituted around 6% of CD4(+)T cells in all MS patient groups, and 7% in HC. There were also no changes in the proportions of CD4(+)CD25(+) Tr cells and CD4(+)CD25(high) Tr cells in a longitudinal follow-up of MS patients before and during IFN-beta treatment. Frequencies of circulating CD4(+)CD25(high)Tr cells among CD4(+) T cells were also similar and their surface or intracellular molecular expression did not vary in MS patients, irrespective of treatment, compared to HC. This study suggests that levels of circulating CD4(+)CD25(+) Tr cells and CD4(+)CD25(high) Tr cells are not altered in MS, and are unaffected by substances currently used to modulate the disease.     

Impaired CD4 and CD8 T cell phenotype and reduced chemokine secretion in recent-onset type 1 diabetic children

Although the role of the T cell-mediated autoimmune reaction in type 1 diabetes (T1D) is conclusive, studies including data from human circulating CD4(+) and CD8(+) lymphocytes subsets during the disease onset and posterior development are scarce. Further, chemokines and chemokine receptors are key players in the migration of pathogenic T cells into the islets of non-obese diabetic mice developing T1D, but few studies have investigated these markers in human T1D patients. We studied the expression of T helper 1 (Th1)- and Th2-associated chemokine receptors, and the two isoforms of CD45 leucocyte antigen on CD4(+) and CD8(+) lymphocytes from T1D and healthy children, as well as the secretion of chemokines in cell supernatants in peripheral blood mononuclear cells. Our results showed increased expression of CCR7 and CD45RA and reduced CD45RO on CD8(+) cells among recent-onset T1D patients. The percentages of CD4(+) cells expressing CXC chemokine receptor 3 (CXCR3), CXCR6 and CCR5, and the secretion of interferon-gamma-induced protein-10, monocyte chemoattractant protein-1, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta was lower among diabetics. Low expression of Th1-associated receptors and secretion of chemokines, together with an increased amount of CD8(+) cells expressing CD45RA and CCR7 in T1D patients therefore might represent suboptimal Th function in T1D, leading to impaired T cytotoxic responses or alternatively reflect a selective recruitment of Th1 cells into the pancreas.     

Blood monocytes, myeloid dendritic cells and the cytokines interleukin (IL)-7 and IL-15 maintain human CD4+ T memory cells with mixed helper/regulatory function

The number and function of human T cells in the periphery are regulated by homeostatic signals received from antigen-presenting cells (APCs) and the common gamma chain (gammac) cytokines interleukin (IL)-7 and IL-15. We found that, in the absence of introduced antigen, blood monocytes or myeloid dendritic cells (MDCs) in the presence of IL-7 and IL-15 (IL-7/IL-15) can regulate CD4(+) T memory (Tm) cell numbers by polyclonal cell proliferation. The dynamics of CD4(+) Tm cell proliferation, in the presence of IL-7/IL-15, was dependent on contact with MDCs and to a lesser extent on contact with monocytes. IL-7/IL-15 either alone or combined with monocytes or MDCs enhanced the proportion of CD4(+) Tm cells with activated and effector phenotype and diminished the helper function of CD4(+) Tm cells. These CD4(+) Tm cells, preconditioned with IL-7/IL-15 alone or with monocytes or MDCs and IL-7/IL-15, reduced T cell-dependent immunoglobulin M (IgM) and IgG responses. This appeared to be a contact-dependent effect involving a reduction in antibody-producing CD27(+) B memory cells, but contact-independent suppression by soluble factors also contributed to the antibody-producing capacity of CD27(+) B memory cells. These results indicate that blood monocytes, MDCs and the cytokines IL-7/IL-15 contribute to homeostasis of CD4(+) Tm cells by regulating their number, activation state and helper/suppressor (regulatory) function. In healthy individuals, this mode of regulating CD4(+) Tm cell homeostasis may provide a basis for the control of autoimmune responses.     

T lymphocyte subset profile and serum alpha-1-antitrypsin in pathogenesis of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is an inflammatory disorder characterized by the presence of non-fully reversible airflow limitation. The study was undertaken to investigate the involvement of alpha-1-antitrypsin (alpha(1)AT) and T lymphocyte subsets in the pathogenesis of COPD. Blood samples of 50 subjects, including 25 healthy volunteers and 25 patients with COPD, were analysed. Serum trypsin inhibitory capacity (STIC) was determined by enzymatic assay. CD4(+) and CD8(+) T lymphocytes were enumerated in heparinized blood using a fluorescence activated cell sorter counter. The STIC in COPD patients was found to be decreased significantly than in controls (P < 0.01). In COPD patients with lower expression levels of alpha(1)AT, a highly significant decrease in the number of CD4(+) T lymphocytes (P < 0.0009) and CD4/CD8 ratio was observed compared with control subjects (P < 0.008). The mean +/- standard error of CD8(+) lymphocytes was found to be little different (only marginally decreased) in COPD patients compared to healthy controls; however, an alteration in the individual count of CD8(+) lymphocytes cells was observed in COPD patients. Using linear regression analysis, a negative correlation was observed between STIC and CD4(+) lymphocytes and CD8(+) lymphocytes (r = -0.40, P < 0.04; r = -0.42, P < 0.03, respectively) in COPD patients. An alteration in alpha(1)AT and T lymphocyte subsets in COPD patients suggested that interplay of these factors may be responsible for the progression of COPD.