Regulatory T cells in health and disease

Impact of supplementation with dihydroxylated vitamin D3 on performance parameters and gut health in weaned Iberian piglets under indoor/outdoor conditions

BACKGROUND

Vitamin D may improve innate antimicrobial response and the integrity of the intestinal mucosal barrier representing an alternative to antibiotics for improving pig health. Therefore, benefits of dietary supplementation with a product based on vitamin D₃ metabolite-rich plant extracts were assessed in 252 purebred Iberian piglets for a period of 60 days. The study group received 1,25 dihydroxyvitamin D (1,25(OH)₂D) (100 ppm) in the conventional feed, which already included vitamin D (2000 IU in the starter and 1000 IU in the adaptation diets, respectively). Average daily gain (ADG), feed conversion ratio (FCR) and coefficient of variation of body weight (CV-BW) were assessed along the study. Blood samples, from 18 animals of the study group and 14 animals of the control group, were collected at selected time points to determine white blood cell count, concentration of vitamin D₃ and its metabolites, and IgA and IgG in serum. Histopathology, morphometry, and immunohistochemistry (IgA and FoxP3) from small intestine samples were performed on days 30 and 60 of the study from 3 animals per group and time point.

RESULTS

The ADG (493 vs 444 g/day) and FCR (2.3 vs 3.02) showed an improved performance in the supplemented animals. Moreover, the lower CV-BW indicated a greater homogeneity in the treated batches (13.17 vs 26.23%). Furthermore, a mild increase of IgA and in the number of regulatory T cells in the small intestine were observed in treated pigs.

CONCLUSIONS

These results highlight the benefits of this supplementation and encourage to develop further studies along other production stages.

Evaluation of CD4+CD25+FOXP3+ regulatory T cells and FOXP3 mRNA in premature ovarian insufficiency

Objective: T cell-mediated injury plays an important role in the pathogenesis of autoimmune premature ovarian insufficiency (POI). The purpose of this study was to assess the percentage of CD4⁺CD25⁺FOXP3⁺ regulatory T (Treg) cells and the level of forkhead box protein 3 (FOXP3) mRNA expression in POI patients.Methods: The case-control study compared 30 POI patients with 30 healthy subjects. Peripheral blood mononuclear cells were collected. The percentage of CD4⁺CD25⁺FOXP3⁺ Treg cells was measured by flow cytometry using specific monoclonal antibodies recognizing the CD4⁺, CD25⁺, and FOXP3⁺ markers. FOXP3 gene expression was evaluated by real-time polymerase chain reaction. In addition, the levels of transforming growth factor-β1 (TGF-β1), interferon-γ (IFN-γ), and adrenal cortex autoantibody (AAA) were determined by enzyme-linked immunosorbent assay.Results: The percentage of CD4⁺CD25⁺FOXP3⁺ Treg cells and the level of FOXP3 mRNA expression were significantly decreased in the POI patients compared with the control subjects. Moreover, the women with POI showed significantly increased levels of IFN-γ and AAA but reduced levels of TGF-β1.Conclusions: Our study suggested that POI may be associated with an abrogated function of circulating CD4⁺CD25⁺FOXP3⁺ Treg cells and a decreased level of FOXP3 gene expression. However, these results require further investigation.

Dietary supplementation of encapsulated organic acids enhances performance and modulates immune regulation and morphology of jejunal mucosa in piglets

The aim of the study was to test two encapsulated regimens containing organic acids and/or zinc oxide (ZnO) on weaned piglet performance and jejunal mucosa morphology and immunity. For that, weaned piglets were allocated to treatments including control, supplemented with encapsulated organic acids (ACID group), and supplemented with organic acids and ZnO, both encapsulated (ACIDplus group). Antibiotics were used at similar concentrations in all groups during the first two weeks, but withdrawn from the ACIDplus group during the last three weeks of the experiment. ZnO was given with feed in the Control and ACID groups only during the first two weeks. The experimental period lasted 5 weeks. Piglets from the ACID group exhibited higher average daily gain compared to other groups during the last 3 weeks of the experiment (P<0.05). The ACIDplus group performed similarly with controls. The mucosal height of jejunum was higher in both ACID (P<0.01) and ACIDplus groups compared to controls (P<0.05). Immunohistochemical analysis of jejunal mucosa, showed higher numbers of neutrophils in ACID and ACIDplus groups compared to controls (P<0.01 and P<0.001, respectively). Treatments had the opposite effect on mucosal regulatory T-cells (Foxp3-positive cells) in jejunum, being higher (P<0.001) in control group compared to ACID and ACIDplus groups. The number of CD3-positive cells was higher (P<0.05) in the ACIDplus and control groups compared to the ACID group. In conclusion, the encapsulated products used had beneficial effects on growth performance coexisting with improvements on jejunal histomorphology and modulation of mucosal immunity.

Interplay of Regulatory T Cell and Th17 Cells during Infectious Diseases in Humans and Animals

It is now clear that the outcome of an inflammatory process caused by infections depends on the balance of responses by several components of the immune system. Of particular relevance is the interplay between regulatory T cells (Tregs) and CD4⁺ T cells that produce IL-17 (Th17 cells) during immunoinflammatory events. In addition to discussing studies done in mice to highlight some unresolved issues in the biology of these cells, we emphasize the need to include outbred animals and humans in analyses. Achieving a balance between Treg and Th17 cells responses represents a powerful approach to control events during immunity and immunopathology.

TGF-β1 and contact mediated suppression by CD4+CD25+CD127- T regulatory cells of patients with self-limiting hepatitis E

BACKGROUND AND AIM

Literature on the role of Regulatory T cells (Tregs) in acute viral infections is limited. Having established that the Tregs in self-limiting hepatitis E infection are elevated and functional, this study has focused on characterizing the specificity, phenotypes and identifying the molecules or factors responsible for enhancement of Treg cells and abrogation of Treg-mediated suppression in hepatitis E.

METHODS

HEV rORF2p specific (a) Treg frequency, subset analysis and expression of surface and intracellular markers on Tregs and CFSE based functional analysis by flow cytometry (b) key cytokines quantification by multiplex (c) suppressive functional assay in the presence of anti-TGF-β₁ or anti-IL-10 or both antibodies or Transwell insert or in combination were performed on samples from 58 acute patients (AVH-E), 45 recovered individuals from hepatitis E and 55 controls.

RESULTS

In AVH-E, the increased frequencies of Tregs and Teff cells were HEV rORF2p specific and Treg cells were of effector memory phenotype. Higher expressions of HEV rORF2p stimulated CTLA-4, GITR, PD1L, CD103, CD39, TLR2 and TGF-β₁ molecules on Tregs of AVH-E were observed. Tregs produced TGF-β₁ and inhibited the secretion of IFN-γ. Transwell insert and cytokines blocking assays indicated Tregs mediated suppression in AVH-E patients is majorly TGF-β₁ mediated and partly cell-cell contact mediated.

CONCLUSION

Overall, we have identified beneficial involvement of HEV specific, functional Tregs and TGF-β₁ as the regulatory molecule responsible for enhancement of Tregs in self-limiting HEV infection. Therefore, use of TGF-β₁ as a possible supplement for boosting Treg response in recovery from severe hepatitis E needs evaluation.

Increased innate and adaptive immune responses in induced sputum of young smokers

BACKGROUND AND OBJECTIVES

It is known that chronic obstructive pulmonary disease (COPD) development process is imperceptible and can be asymptomatic for 20 or more years. It is of great importance to diagnose early inflammatory changes that can lead to COPD in young asymptomatic cigarette smokers. The aim of our study was to analyze the cell spectrum of induced sputum (IS) of young cigarette smokers, with emphasis on T-regulatory cells.

MATERIALS AND METHODS

A total of 20 healthy nonallergic smokers, 20 nonsmokers and 20 COPD patients were enrolled in the study. After lung function measurements were taken, we performed sputum induction and analyzed sputum cells. We evaluated the cell count of FOXP3-positive, CD4⁺ and CD8⁺ T lymphocytes by immunocytochemistry staining, and the cell count of macrophages and neutrophils by May-Grünwald Giemsa staining.

RESULTS

Induced sputum of smokers contained a higher absolute amount of macrophages and neutrophils when compared to nonsmokers. FOXP3-positive cells in the sputum of young smokers showed a statistically significant increase when compared to nonsmokers. Induced sputum of COPD patients contained an increased absolute amount of neutrophils and FOXP3-positive Treg cells when compared to nonsmokers. Regression analysis showed that the amount of FOXP-3 positive cells, neutrophils and macrophages in the induced sputum was increasing with the number of pack years.

CONCLUSIONS

This study demonstrates that young smokers have early inflammatory changes in their airways that not only initiate nonspecific mechanisms recruiting neutrophils, but also involve specific immune mechanisms with recruitment of T regulatory lymphocytes. The lymphocyte response is probably adaptive.

Cellular immunity profile in children with congenital heart disease and bronchopneumonia: evaluation of lymphocyte subsets and regulatory T cells

Children with congenital heart disease (CHD) have a predisposition to suffer from respiratory tract infections, such as bronchopneumonia (BP). In this study we investigated the characterization of lymphocyte subsets and regulatory T cells (Tregs) in these children. The frequencies of lymphocyte subsets and regulatory T cells were detected in peripheral blood of 400 children patients [100 with BP only, 100 with BP and CHD (BPCHD), 100 with BP and heart failure (BPHF), 100 healthy volunteers] by using three-color flow cytometry. In BPHF and BPCHD groups, lymphocyte subsets characterization of patients was analogous, with lower levels of CD3+, CD3+CD4+, CD3+CD8+, and CD4+/CD8+ ratio but higher levels of CD19+ and CD3-CD16+CD56+ in comparison to BP patients. The differences of the frequencies of CD4+CD25+CD127- T-cells in the four groups were not statistically significant. It was concluded that the cellular immunity function of children with CHD was vulnerable to being damaged after having suffered from BP when compared with the children without CHD, which might be associated with blood circulation difficulties in the majority of children with CHD.

T regulatory lymphocytes in patients with endometriosis

The present study aimed to investigate the presence of T regulatory cells (Tregs) in the peripheral blood (PB) and peritoneal fluid (PF) in females with endometriosis. The present study included 42 patients who underwent laparoscopy between 2010 and 2011. Flow cytometry was used to determine the percentage of Tregs in the PF and PB of the patients. No significant difference was observed in the percentage of Tregs in the patients in the endometriosis group compared with those in the control group in the PF (9.1±5.4 vs. 9.1±3.8%) or the PB (6.5±3.2 vs. 6.5±3.7%). However, the percentage of Tregs was found to be higher in the PF compared with the PB in the patients in the endometriosis and control groups, but significance was found only in those in the control group. Furthermore, no significant difference was observed in the Treg concentration in the patients with early stage (I/II) endometriosis compared with those with late stage (III/IV) endometriosis. Moreover, no significant correlation was found between the percentage of Tregs and the white blood cell count, lymphocyte count or CA125 concentration in the patients. These findings suggest that the local host‑defense mechanism is deficient in patients with endometriosis, thus endometriosis should not be treated as an autoimmune condition.

The effect of citrus peel extracts on cytokines levels and T regulatory cells in acute liver injury

Background. T cell-mediated immune responses contribute to the hepatocellular injury during autoimmune hepatitis, viral infection, and hepatotoxins. Pharmacological compounds regulating immune responses are suitable candidates for prevention/treatment of this pathology. Therefore, the main aim of this study was to define the effects of antioxidant, anti-inflammatory mixture of citrus peel extract (CPE) on the immune-mediated liver injury. Methods. The influence of CPE on liver injury was determined by the activity of transaminases in plasma and the histological changes. Anti-inflammatory and antioxidant effects were studied by measuring frequency of T regulatory cells (Tregs), cytokines (TNF-α, IL-10, and IFN-γ), and nitric oxide levels. Results. The CPE application notably prevents development of liver injury through decreasing levels of both cytokines (TNF-alpha, INF) and regulatory T cells and increasing levels of IL-10. CPE injection also diminished the serum NO, which in turn resulted in evident reduction of the liver damage. Conclusion. Our findings represent the primary preclinical data indicating that the CPE in vivo could ameliorate Con A induced hepatitis. The low dose of CPE most likely can be used for the treatment of the T cell-mediated liver injury as in autoimmune hepatitis, alcoholic hepatitis, and chronic viral hepatitis.

CD4+ T cell subsets and Tax expression in HTLV-1 associated diseases

Human T lymphotropic virus type 1 (HTLV-1) infection displays variable clinical manifestations. These include inflammatory diseases such as HTLV-1 associated myelopathy (HAM) or immunosuppressive conditions such as Strongyloides stercoralis hyperinfection. The viral protein, Tax causes activation and proliferation of T cells. We hypothesize that the expression of Tax in T cell subsets characterizes the clinical manifestations of HTLV-1. To test this hypothesis, we measured T helper 1 effector cells and regulatory T cells (Tregs) among Tax expressing lymphocytes from peripheral blood mononuclear cells (PBMCs) of 32 HTLV-1 infected patients with HAM, with S. stercoralis co-infection or with asymptomatic infection. We observed increased ratios of Th1/Treg among Tax expressing lymphocytes in HAM patients. These data suggest that the expression of Tax among the different target cells may explain the variable presentation of HTLV-1.

Regulation of interferon gamma signaling by suppressors of cytokine signaling and regulatory T cells

Regulatory T cells (Tregs) play an indispensable role in the prevention of autoimmune disease, as interferon gamma (IFNγ) mediated, lethal auto-immunity occurs (in both mice and humans) in their absence. In addition, Tregs have been implicated in preventing the onset of autoimmune and auto-inflammatory conditions associated with aberrant IFNγ signaling such as type 1 diabetes, lupus, and lipopolysaccharide (LPS) mediated endotoxemia. Notably, suppressor of cytokine signaling-1 deficient (SOCS1^−/−) mice also succumb to a lethal auto-inflammatory disease, dominated by excessive IFNγ signaling and bearing similar disease course kinetics to Treg deficient mice. Moreover SOCS1 deficiency has been implicated in lupus progression, and increased susceptibility to LPS mediated endotoxemia. Although it has been established that Tregs and SOCS1 play a critical role in the regulation of IFNγ signaling, and the prevention of lethal auto-inflammatory disease, the role of Treg/SOCS1 cross-talk in the regulation of IFNγ signaling has been essentially unexplored. This is especially pertinent as recent publications have implicated a role of SOCS1 in the stability of peripheral Tregs. This review will examine the emerging research findings implicating a critical role of the intersection of the SOCS1 and Treg regulatory pathways in the control of IFN gamma signaling and immune system function.

Immunophenotypic characterization of lymphoid cell infiltrates in vitiligo

The pathogenesis of vitiligo is still controversial. The purpose of this study was to gain insight into the nature of lymphoid cells infiltrating depigmented areas of skin in vitiligo. Immunochemical procedures were carried out in biopsies from 20 patients with active lesions to search for cells expressing CD1a, CD2, CD3, CD4, CD5, CD8, CD20, CD25, CD30, CD56, CD68 and CD79a. Results indicate that early lesions are infiltrated mainly by dendritic cells, whereas older lesions display significantly lower proportions of these cells and increased percentages of mature T cells. This finding might suggest that the autoimmune reactivity towards melanocyte antigens might be T cell-dependent and antigen-driven. It is possible that a non-immune offence of melanocytes is responsible for the exposure of intracellular antigens, while autoreactivity might be a secondary, self-perpetuating mechanism.

Dendritic cells in the pathogenesis and treatment of human diseases: a Janus Bifrons?

Dendritic cells (DCs) represent the bridging cell compartment between a variety of nonself antigens (i.e., microbial, cancer and vaccine antigens) and adaptive immunity, orchestrating the quality and potency of downstream immune responses. Because of the central role of DCs in the generation and regulation of immunity, the modulation of DC function in order to shape immune responses is gaining momentum. In this respect, recent advances in understanding DC biology, as well as the required molecular signals for induction of T-cell immunity, have spurred many experimental strategies to use DCs for therapeutic immunological approaches for infections and cancer. However, when DCs lose control over such 'protective' responses - by alterations in their number, phenotype and/or function - undesired effects leading to allergy and autoimmune clinical manifestations may occur. Novel therapeutic approaches have been designed and currently evaluated in order to address DCs and silence these immunopathological processes. In this article we present recent concepts of DC biology and some medical implications in view of therapeutic opportunities.

Immunohistochemical characterization of lymphocyte and myeloid cell infiltrates in spirocercosis-induced oesophageal nodules

Spirocerca lupi is a nematode that infects the dog's oesophagus and promotes the formation of an inflammatory fibroblastic nodule that progresses to sarcoma in approximately 25% of cases. Spirocercosis-associated oesophageal sarcoma is an excellent and under-utilized spontaneous model of parasite-associated malignancy. The inflammatory infiltrate of paraffin-embedded, non-neoplastic oesophageal nodules (n = 46), neoplastic nodules (n = 25) and normal oesophagus (n = 14) was examined by immunohistochemistry using MAC387 (myeloid cells), CD3 (T cells), Pax5 (B cells) and FoxP3 (T regulatory cells) antibodies. Myeloid cells predominated in 70% of nodules, in pockets around the worms' migratory tracts and in necro-ulcerative areas in neoplastic cases. T cells predominated in 23% of cases with a focal or diffuse distribution, in the nodule periphery. No significant differences were observed between neoplastic and non-neoplastic stages. FoxP3+ cells were observed in low numbers, not significantly different from the controls. The inflammation in spirocercosis is characterized by pockets of pus surrounded by organized lymphoid foci. There was no evidence of a local accumulation of FoxP3+ cells, unlike many previous studies that have reported an increase in FoxP3+ T cells in both malignancies and parasite infections. The triggering factor(s) driving the malignant transformation of the spirocercosis-associated chronic inflammatory nodule warrants further investigation.

Systems biology approach to transplant tolerance: proof of concept experiments using RNA interference (RNAi) to knock down hub genes in Jurkat and HeLa cells in vitro

BACKGROUND

Systems biology is gaining importance in studying complex systems such as the functional interconnections of human genes [1]. To investigate the molecular interactions involved in T cell immune responses, we used databases of physical gene-gene interactions to constructed molecular interaction networks (interconnections) with R language algorithms. This helped to identify highly interconnected "hub" genes AT(1)P5C1, IL6ST, PRKCZ, MYC, FOS, JUN, and MAPK1. We hypothesized that suppression of these hub genes in the gene network would result in significant phenotypic effects on T cells and examined this in vitro. The molecular interaction networks were then analyzed and visualized with Cytoscape.

MATERIALS AND METHODS

Jurkat and HeLa cells were transfected with siRNA for the selected hub genes. Cell proliferation was measured using ATP luminescence and BrdU labeling, which were measured 36, 72, and 96 h after activation.

RESULTS

Following T cell stimulation, we found a significant decrease in ATP production (P < 0.05) when the hub genes ATP5C1 and PRKCZ were knocked down using siRNA transfection, whereas no difference in ATP production was observed in siRNA transfected HeLa cells. However, HeLa cells showed a significant (P < 0.05) decrease in cell proliferation when the genes MAPK1, IL6ST, ATP5C1, JUN, and FOS were knocked down.

CONCLUSION

In both Jurkat and HeLa cells, targeted gene knockdown using siRNA showed decreased cell proliferation and ATP production in both Jurkat and HeLa cells. However, Jurkat T cells and HELA cells use different hub genes to regulate activation responses. This experiment provides proof of principle of applying siRNA knockdown of T cell hub genes to evaluate their proliferative capacity and ATP production. This novel concept outlines a systems biology approach to identify hub genes for targeted therapeutics.

Inhibition of SOCS1-/- lethal autoinflammatory disease correlated to enhanced peripheral Foxp3+ regulatory T cell homeostasis

Suppressor of cytokine signaling 1-deficient (SOCS1(-/-)) mice, which are lymphopenic, die <3 wk after birth of a T cell-mediated autoimmune inflammatory disease characterized by leukocyte infiltration and destruction of vital organs. Notably, Foxp3(+) regulatory T cells (Tregs) have been shown to be particularly potent in inhibiting inflammation-associated autoimmune diseases. We observed that SOCS1(-/-) mice were deficient in peripheral Tregs despite enhanced thymic development. The adoptive transfer of SOCS1-sufficient Tregs, CD4(+) T lymphocytes, or administration of SOCS1 kinase inhibitory region (KIR), a peptide that partially restores SOCS1 function, mediated a statistically significant but short-term survival of SOCS1(-/-) mice. However, the adoptive transfer of SOCS1-sufficient CD4(+) T lymphocytes, combined with the administration of SOCS1-KIR, resulted in a significant increase in the survival of SOCS1(-/-) mice both short and long term, where 100% death occurred by day 18 in the absence of treatment. Moreover, the CD4(+)/SOCS1-KIR combined therapy resulted in decreased leukocytic organ infiltration, reduction of serum IFN-γ, and enhanced peripheral accumulation of Foxp3(+) Tregs in treated mice. These data show that CD4(+)/SOCS1-KIR combined treatment can synergistically promote the long-term survival of perinatal lethal SOCS1(-/-) mice. In addition, these results strongly suggest that SOCS1 contributes to the stability of the Foxp3(+) Treg peripheral population under conditions of strong proinflammatory environments.

HLA DRB1*1503 allelic haplotype predominance and associated immunodysregulation in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic, relapsing, and remitting disease affecting primarily African American females of child bearing age. Familial aggregation of this disease suggests that at least part of the susceptibility for this disease is genetic, although environmental and hormonal influences are also likely to play a role. Early studies of genetic susceptibility to SLE revealed several of the major histocompatibility complex molecules, namely HLA DR, to be linked to SLE. Meta-analysis of genome scans has yielded loci significant for lupus patients, one of which includes the MHC region. Regulatory T cells are immunoregulatory cells that modulate activated immune cells. These cells play a large role in homeostasis of the immune responses and maintenance of immunologic tolerance, i.e., prevention of autoimmunity. Decreased numbers of regulatory T cells have been described in many autoimmune diseases, including systemic lupus erythematosus. Autoantibody production in systemic lupus erythematosus and the resulting immune complex formation and complex deposition into tissues are arguably the central core of immune dysregulation leading to disease manifestations and symptoms. Inability of the immune system to recognize and inhibit autoreactive immune cells in this particular autoimmune disease may be the result of inappropriate numbers and function of regulatory T cells. This study aims to characterize the immune cell population in patients from our community suffering from systemic lupus erythematosus and to prove that these patients exhibit a unique cellular profile compared to healthy age, race and gender matched control subjects. Surprisingly, our findings demonstrate that patients from the local Mississippi area exhibit increased proportions of CD25(+) FoxP3(+) regulatory T cells and CD25(+) FoxP3(-) T cells (of CD45(+) CD3(+) CD4(+) helper T cells) as compared to healthy controls. HLA tissue-typing of these lupus patients revealed a prominent subgroup (~30%) of patients possessing the HLA DRB1*1503 allele. The investigation of this subgroup demonstrated regulatory T cell composition similar to that of the total lupus group and to that of the non-HLA DRB1*1503 subgroup. Genetic analysis for molecular gene expression levels of various lupus-associated genes by real-time PCR demonstrated a unique profile as compared to healthy controls. Increased gene expression of FoxP3 together with decreased gene expression levels of GATA3, TNFAIP3, and TNFSF4 suggest that variations in gene products compared to healthy controls may be playing a role in the immune cell dysregulation and disproportionate CD25(+) FoxP3(+) regulatory T cells.

Association of environment and place of birth with asthma in Chinese immigrant children

Despite the advances in perinatal and neonatal care and use of newer potent antibiotics, the incidence of neonatal sepsis remains high and the outcome is still severe. For years, investigators have sought a test or panel of tests able to identify septic neonates accurately and rapidly in order to obtain an early diagnosis and develop a specific effective treatment for a successful outcome. In addition to the standard procedures (blood, CSF, and urine cultures, chest x-ray), such panels have included a combination of total and differential cell counts, total immature neutrophil counts, immature to total neutrophil ratio, platelet counts, and levels of acute-phase reactants and cytokines. Furthermore, the science of proteomics and genomics has been applied to the search for biomarkers, production of protein profiles and genetic polymorphisms that can rapidly help the prediction, early diagnosis, and treatment of human diseases, but, for now, data are as yet insufficient to confirm their validity.

Heme oxygenase in the regulation of vascular biology: from molecular mechanisms to therapeutic opportunities

Heme oxygenases (HOs) are the rate-limiting enzymes in the catabolism of heme into biliverdin, free iron, and carbon monoxide. Two genetically distinct isoforms of HO have been characterized: an inducible form, HO-1, and a constitutively expressed form, HO-2. HO-1 is a kind of stress protein, and thus regarded as a sensitive and reliable indicator of cellular oxidative stress. The HO system acts as potent antioxidants, protects endothelial cells from apoptosis, is involved in regulating vascular tone, attenuates inflammatory response in the vessel wall, and participates in angiogenesis and vasculogenesis. Endothelial integrity and activity are thought to occupy the central position in the pathogenesis of cardiovascular diseases. Cardiovascular disease risk conditions converge in the contribution to oxidative stress. The oxidative stress leads to endothelial and vascular smooth muscle cell dysfunction with increases in vessel tone, cell growth, and gene expression that create a pro-thrombotic/pro-inflammatory environment. Subsequent formation, progression, and obstruction of atherosclerotic plaque may result in myocardial infarction, stroke, and cardiovascular death. This background provides the rationale for exploring the potential therapeutic role for HO system in the amelioration of vascular inflammation and prevention of adverse cardiovascular outcomes.

Heme oxygenase in the regulation of vascular biology: from molecular mechanisms to therapeutic opportunities

Heme oxygenases (HOs) are the rate-limiting enzymes in the catabolism of heme into biliverdin, free iron, and carbon monoxide. Two genetically distinct isoforms of HO have been characterized: an inducible form, HO-1, and a constitutively expressed form, HO-2. HO-1 is a kind of stress protein, and thus regarded as a sensitive and reliable indicator of cellular oxidative stress. The HO system acts as potent antioxidants, protects endothelial cells from apoptosis, is involved in regulating vascular tone, attenuates inflammatory response in the vessel wall, and participates in angiogenesis and vasculogenesis. Endothelial integrity and activity are thought to occupy the central position in the pathogenesis of cardiovascular diseases. Cardiovascular disease risk conditions converge in the contribution to oxidative stress. The oxidative stress leads to endothelial and vascular smooth muscle cell dysfunction with increases in vessel tone, cell growth, and gene expression that create a pro-thrombotic/pro-inflammatory environment. Subsequent formation, progression, and obstruction of atherosclerotic plaque may result in myocardial infarction, stroke, and cardiovascular death. This background provides the rationale for exploring the potential therapeutic role for HO system in the amelioration of vascular inflammation and prevention of adverse cardiovascular outcomes.

Decreased ratio of CD8+ T cells to regulatory T cells associated with decreased survival in dogs with osteosarcoma

BACKGROUND

Increased numbers of regulatory T cells (Treg) and decreased ratios of CD8+ T cells to Treg have been shown to correlate with decreased survival times (ST) in humans with certain malignancies. A possible connection between Treg and ST in dogs with cancer has not been investigated previously.

HYPOTHESIS

The purpose of this study was to compare numbers of Treg and T lymphocyte subsets in dogs with osteosarcoma (OSA) to those of healthy dogs and to determine whether pretreatment values were associated with disease-free interval or with ST. We hypothesized that Treg numbers would be increased in dogs with cancer and that dogs with a high percentage of Treg would have a poorer prognosis.

ANIMALS

Twelve client-owned dogs with appendicular OSA were entered into a prospective clinical trial. Twenty-two healthy dogs were used as controls.

METHODS

The percentages and numbers of Treg and CD4+ and CD8+ T cells in blood, lymph nodes, and tumors were determined with flow cytometry and compared between dogs with OSA and control dogs.

RESULTS

Dogs with OSA had significantly fewer circulating CD8+ T cells and significantly more Treg compared with healthy dogs. The CD8/Treg ratio also was significantly lower in dogs with OSA compared with control dogs. In dogs with OSA, a decreased CD8/Treg ratio was associated with significantly shorter STs.

CONCLUSIONS

These data support a role for Treg in the immune control of canine OSA and suggest that determination of the CD8/Treg ratio may be useful for assessing outcomes.

Interleukin-17-producing T helper cells in autoimmunity

With all the incredible progress in scientific research over the past two decades, the trigger of the majority of autoimmune disorders remains largely elusive. Research on the biology of T helper type 17 (T(H)17) cells over the last decade not only clarified previous observations of immune regulations and disease manifestations, but also provided considerable information on the signaling pathways mediating the effects of this lineage and its seemingly dual role in fighting the invading pathogens on one hand, and in frightening the host by inducing chronic inflammation and autoimmunity on the other hand. In this context, recent reports have implicated T(H)17 cells in mediating host defense as well as a growing list of autoimmune diseases in genetically-susceptible individuals. Herein, we summarize the current knowledge on T(H)17 in autoimmunity with emphasis on its differentiation factors and some mechanisms involved in initiating pathological events of autoimmunity.

Neutrophils in rheumatoid arthritis: More than simple final effectors

Rheumatoid arthritis is the most common inflammatory joint disease. The etiopathogenesis of this condition has been classically explained by a T cell-driven process. However, recent studies have highlighted the possible contribution of neutrophils for the early phases of RA physiopathology. These cells are phagocytic leukocytes that play crucial roles in the acute defense against pathogens while modulating the function of other immune cells and contributing to the perpetuation of an initial inflammatory response. The herein article reviews recent progresses in the understanding of the immunopathology of RA with a special emphasis on the role of neutrophils.

T-cell epitope mapping

Identification of epitopes defined by T-cell responses aids to (1) monitor antigen-specific cellular immune responses (2) guide rational vaccine design, and (3) understand the nature of protective or harmful T-cell responses in diseases with defined target antigens. The 6-h intracellular cytokine staining (ICS) assay preferentially identifies effector T cells that are readily detectable in the peripheral circulation. In contrast, the whole blood assay (WBA) allows to gauge expansion of antigen-specific T cells over time (7 days), i.e., T cells with lower frequencies (e.g., memory T cells) defined by proliferation and cytokine production. Any cellular immune profile can be measured in the WBA (using the 7 days cell culture supernatants) or directly in responder T cells after antigenic stimulation (in the ICS) with appropriate cytokine-specific detection systems. The choice of the cytokine test panel depends on the nature of the expected immune response. A broad panel of candidate peptides can be tested for T-cell recognition in the WBA due to its simplicity and the low input of (unprocessed, heparinized) blood.

Decrease in phenotypic regulatory T cells in subsets of patients with common variable immunodeficiency

Common variable immunodeficiencies (CVID) are a heterogeneous group of antibody deficiency disorders complicated by autoimmune, lymphoproliferative and/or granulomatous manifestations, suggesting variations in immunoregulation. We sought to quantify regulatory CD4 T cells (T(reg) cells) in the blood of CVID patients and to correlate the frequency with clinical manifestations and classification subgroups. Blood samples from 99 CVID patients in Freiburg, London and Sydney, who had been phenotyped clinically and stratified according to their memory B cell phenotype (Freiburg and Paris classification schemes), were analysed for the proportion of T(reg) cells, defined either as CD25(+)/forkhead box P3 (FoxP3)(+), CD25(+)/CD127(low)/FoxP3(+) or CD25(+)/CD127(low) CD4(+) T cells, and results compared with 49 healthy controls. Irrespective of the phenotype used to define them, there was a significant decrease in the T(reg) cell proportion in patients with granulomatous disease and immune cytopenias. This allowed the definition of a subgroup of CVID patients with abnormally low T(reg) cells, which had a higher rate of these two manifestations as well as autoimmune disease in general. There was also a significant reduction in the proportion of T(reg) cells in the Freiburg group Ia compared with other CVID patients and controls, but there were no differences between the Paris groups. The reduction in T(reg) cells in subsets of CVID patients may be relevant to their clinical manifestations, and may contribute to our understanding of the pathogenesis of CVID complications.

Role of T-lymphocytes and pro-inflammatory mediators in the pathogenesis of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the US and a major worldwide healthcare problem. The pathophysiologic mechanisms that drive development and progression of this disease are complex and only poorly understood. While tobacco smoking is the primary risk factor, other disease processes also appear to play a role. Components of the innate immune system (eg, macrophages and neutrophils) have long been believed to be important in the development of COPD. More recent evidence also suggests involvement of the adaptive immune system in pathogenesis of this disease. Here we will review the literature supporting the participation of T-cells in the development of COPD, and comment on the potential antigenic stimuli that may account for these responses. We will further explore the prospective contributions of T-cell derived mediators that could contribute to the inflammation, alveolar wall destruction, and small airway fibrosis of advanced COPD. A better understanding of these complex immune processes will lead to new insights that could result in improved preventative and/or treatment strategies.

T regulatory cells: an overview and intervention techniques to modulate allergy outcome

Dysregulated immune response results in inflammatory symptoms in the respiratory mucosa leading to asthma and allergy in susceptible individuals. The T helper type 2 (Th2) subsets are primarily involved in this disease process. Nevertheless, there is growing evidence in support of T cells with regulatory potential that operates in non-allergic individuals. These regulatory T cells occur naturally are called natural T regulatory cells (nTregs) and express the transcription factor Foxp3. They are selected in the thymus and move to the periphery. The CD4 Th cells in the periphery can be induced to become regulatory T cells and hence called induced or adaptive T regulatory cells. These cells can make IL-10 or TGF-b or both, by which they attain most of their suppressive activity. This review gives an overview of the regulatory T cells, their role in allergic diseases and explores possible interventionist approaches to manipulate Tregs for achieving therapeutic goals.

Cancer metastasis is accelerated through immunosuppression during Snail-induced EMT of cancer cells

Epithelial-mesenchymal transition (EMT) is a key step toward cancer metastasis, and Snail is a major transcription factor governing EMT. Here, we demonstrate that Snail-induced EMT accelerates cancer metastasis through not only enhanced invasion but also induction of immunosuppression. Murine and human melanoma cells with typical EMT features after snail transduction induced regulatory T cells and impaired dendritic cells in vitro and in vivo partly through TSP1 production. Although Snail(+) melanoma did not respond to immunotherapy, intratumoral injection with snail-specific siRNA or anti-TSP1 monoclonal antibody significantly inhibited tumor growth and metastasis following increase of tumor-specific tumor-infiltrating lymphocytes and systemic immune responses. These results suggest that inhibition of Snail-induced EMT could simultaneously suppress both tumor metastasis and immunosuppression in cancer patients.

End-stage renal failure and regulatory activities of CD4+CD25bright+FoxP3+ T-cells

BACKGROUND

The defensive immune system in patients with end-stage renal failure is impaired at multiple levels. This state of immune incompetence is associated with continuous activation of the immune system. An additional explanation for this state of activation may be the disturbed function of CD4(+)CD25(bright+)FoxP3(+) regulatory T-cells.

METHODS

The phenotype and function of peripheral regulatory T-cells from patients with end-stage renal failure (N = 80) and healthy controls (N = 17) was studied by flow cytometry, RT-PCR and mixed lymphocyte reaction. Patients were on haemodialysis (N = 40), peritoneal dialysis (N = 26) or not treated with dialysis yet (N = 14). The latter group had a glomerular filtration rate of <20 ml/min/ 1.73 m(2).

RESULTS

The basal IL-2 mRNA level was high in patient-PBMC (P = 0.0002 versus healthy controls). The absolute number of CD4(+)CD25(bright+) T-cells was low in patients (P < 0.05 versus healthy controls). Furthermore, proliferation of patient-PBMC upon allogeneic stimulation was impaired (P < 0.0001 versus healthy controls). The regulatory function of CD4(+)CD25(bright+) T-cells was determined in the setting of direct allorecognition. First, the effect of depletion of CD25(bright+) cells from patient-PBMC on proliferation was low. Second, co-culture of CD25(bright+) cells with CD25(neg/dim) cells (1:10 ratio) showed impaired regulatory function (P < 0.001 versus healthy controls), which was especially pronounced in patients on dialysis. The FOXP3 mRNA level was also low upon stimulation (P = 0.0002 versus healthy controls).

CONCLUSIONS

In line with previous studies, we observed an overactivated but functionally compromised immune system in patients with end-stage renal failure. It now appears that in this setting, regulation by CD4(+)CD25(bright+)FoxP3(+) T-cells is also impaired.

Inhibitory CD8+ T cells in autoimmune disease

Rheumatologists have long been focused on developing novel immunotherapeutic agents to manage such prototypic autoimmune diseases as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). The ultimate challenge in providing immunosuppressive treatment for patients with RA and SLE has derived from the dilemma that both protective and harmful immune responses result from adaptive immune responses, mediated by highly diverse, antigen-specific T and B cells endowed with powerful effector functions and the ability for long-lasting memory. As regulatory/suppressor T cells can suppress immunity against any antigen, including self-antigens, they emerge as an ideal therapeutic target. Several distinct subtypes of CD8(+) suppressor cells (Ts) have been described that could find application in treating RA or SLE. In a xenograft model of human synovium, CD8(+)CD28(-)CD56(+) T cells effectively suppressed rheumatoid inflammation. Underlying mechanisms involve conditioning of antigen presenting cells (APC). Adoptively transferred CD8(+) T cells characterized by IL-16 secretion have also exhibited disease-inhibitory effects. In mice with polyarthritis, CD8(+) Ts suppressed inflammation by IFNgamma-mediated modulation of the tryptophan metabolism in APC. In SLE animal models, CD8(+) Ts induced by a synthetic peptide exerted suppressive activity mainly via the TGFbeta-Foxp3-PD1 pathway. CD8(+) Ts induced by histone peptides were found to downregulate disease activity by secreting TGFbeta. In essence, disease-specific approaches may be necessary to identify CD8(+) Ts optimally suited to treat immune dysfunctions in different autoimmune syndromes.

A novel virus carrier state to evaluate immunotherapeutic regimens: regulatory T cells modulate the pathogenicity of antiviral memory cells

Restrictions in the diversity of an adaptive immune repertoire can facilitate viral persistence. Because a host afflicted with an immune deficiency is not likely to purge a persistent infection using endogenous mechanisms, it is important to explore adoptive therapies to supplement the host with a functional immune defense. In this study, we describe a virus carrier state that results from introducing lymphocytic choriomeningitis virus (LCMV) into adult mice possessing a restricted T cell repertoire. On infection of these mice, LCMV establishes systemic persistence, and within the CNS the virus infects astrocytes (and later oligodendrocytes) rather than its traditional parenchymal target neurons. To determine whether LCMV could be purged from a novel target selection in the absence of an endogenous immune repertoire, we adoptively transferred virus-specific memory cells into adult carrier mice. The memory cells purged virus from the periphery as well as the CNS, but they induced fatalities not typically associated with adoptive immunotherapy. When the repertoire of the recipient mice was examined, a deficiency in natural regulatory T cells was noted. We therefore supplemented carrier mice with regulatory T cells and simultaneously performed adoptive immunotherapy. Cotransfer of regulatory T cells significantly reduced mortality while still permitting the antiviral memory cells to purge the persistent infection. These data indicate that regulatory T cells can be used therapeutically to lessen the pathogenicity of virus-specific immune cells in an immunodeficient host. We also propose that the novel carrier state described herein will facilitate the study of immunotherapeutic regimens.

IL-10 and natural regulatory T cells: two independent anti-inflammatory mechanisms in herpes simplex virus-induced ocular immunopathology

Two prominent anti-inflammatory mechanisms involved in controlling HSV-1-induced corneal immunopathology (stromal keratitis or SK) are the production of the cytokine IL-10 and the activity of natural regulatory T cells (nTregs). It is not known whether, under in vivo conditions, IL-10 and nTregs influence the corneal pathology independently or in concert. In the current study using wild-type and IL-10(-/-) animals, we have assessed the activity of nTregs in the absence of IL-10 both under in vitro and in vivo conditions. The IL-10(-/-) animals depleted of nTregs before ocular infection showed more severe SK lesions as compared with the undepleted IL-10(-/-) animals. In addition, nTregs purified from naive WT and IL-10(-/-) animals were equally able to suppress the proliferation and the cytokine production from anti-CD3-stimulated CD4(+)CD25(-) T cells in vitro. Furthermore, intracellular cytokine staining results indicated that nonregulatory cells expressing B220 and CD25 markers were the major IL-10-producing cell types in the lymphoid tissues of HSV-infected mice. In contrast, in the infected corneas, cells with the CD11b(+)Gr1(+) phenotype along with a minor population of Foxp3(-)CD4(+) and a few F4/80(+) cells produced IL-10. Our current investigations indicate that at least two independent anti-inflammatory mechanisms are involved in limiting the corneal lesions in SK, both of which may need to be modulated to control SK therapeutically.

In vitro-generated antigen-specific CD4+ CD25+ Foxp3+ regulatory T cells control the severity of herpes simplex virus-induced ocular immunoinflammatory lesions

Generating and using regulatory T cells (Tregs) to modulate inflammatory disease represents a valuable approach to therapy but has not yet been applied as a means to control virus-induced immunopathological reactions. In this report, we developed a simplified technique that used unfractionated splenocytes as a precursor population and showed that stimulation under optimized conditions for 5 days with solid-phase anti-CD3 monoclonal antibody in the presence of transforming growth factor beta (TGF-beta) and interleukin-2 could induce up to 90% of CD4(+) T cells to become Foxp3(+) and able to mediate suppression in vitro. CD11c(+) dendritic cells were intricately involved in the conversion process and, once modified in the presence of TGF-beta, could convert Foxp3(-) CD4(+) cells into Foxp3(+) CD4(+)cells by producing TGF-beta. The converted cells had undergone cell division, and the majority of them expressed activation markers along with surface molecules that would facilitate their migration into tissue sites. The primary reason for our study was to determine if such in vitro-converted Tregs could be used in vivo to influence the outcome of a virus-induced immunoinflammatory lesion in the eye caused by herpes simplex virus infection. We could show in three separate models of herpetic stromal keratitis that adoptive transfers of in vitro-converted Tregs effectively diminished lesion severity, especially when given in the initial phases of infection. The suppression effect in vivo appeared to be polyspecific. The protocol we have developed could provide a useful additional approach to control virus-induced inflammatory disease.

Analysis of regulatory T-cell changes in patients with idiopathic thrombocytopenic purpura receiving B cell-depleting therapy with rituximab

The effects of B-cell depletion with rituximab on regulatory T cells (Tregs) have not been determined. We investigated Tregs in patients receiving rituximab for chronic idiopathic thrombocytopenic purpura (ITP). The peripheral blood Tregs, identified as CD4+FOXP3+ T cells, were measured by flow cytometry prior to and after the immunotherapy. In addition, Tregs were analyzed for their usage of the T-cell receptor (TCR) beta-variable (VB) region gene as well as their regulatory function as assessed by cell proliferation assays. Pretreatment data revealed a reduced number and a defective suppressive capacity of Tregs in ITP patients compared with control individuals. In addition, Tregs showed a polyclonal spectratype. Patients, particularly responders, showed restored numbers of Tregs as well as a restored regulatory function upon treatment with rituximab. These results indicate that patients with active ITP have a defective T regulatory cell compartment that can be modulated by a B cell-targeted therapy.

Recent developments in the immunobiology of rheumatoid arthritis

Progress into the understanding of immunopathology in rheumatoid arthritis is reviewed in the present article with regard to pro-inflammatory cytokine production, cell activation and recruitment, and osteoclastogenesis. Studies highlight the potential importance of T helper 17 cells and regulatory T cells in driving and suppressing inflammation in rheumatoid arthritis, respectively, and highlight other potential T-cell therapeutic targets. The genetic associations of the HLA shared epitope alleles with antibodies to citrullinated peptides in rheumatoid arthritis patients indicate that T cells are providing help to B cells to produce autoantibodies, and there is increasing evidence that these autoantibodies are pathogenic in rheumatoid arthritis.

Lymphocyte subpopulations in human exposure to metals (IUPAC Technical Report)

Numerous species of metal ions cause immunosensitization in humans. Possible approaches to determine those occupational and environmental exposures to metals that result in immunological changes include lymphocyte transformation assay, cytokine profiling, and measurement of lymphocyte subpopulations. In two previous papers, we considered lymphocyte transformation assay [1] and cytokine profiling [2]. Here we review the effects of exposures to metals on lymphocyte subpopulations. Specific consideration is given to beryllium, chromium, cobalt, nickel, palladium and platinum, cadmium, gold, mercury, and lead. Analysis of the scientific literature shows that immunosensitizing metals may have influences on the lymphocyte subset composition, but only in a few instances does exposure to metals cause reproducible shifts of lymphocyte subpopulations. If lymphocyte subpopulations are analyzed, each diagnostic step, including indication, sample handling, analytic procedure, and data interpretation, should adhere to good quality assurance and quality control.

Genetic vaccine for tuberculosis (pVAXhsp65) primes neonate mice for a strong immune response at the adult stage

Background

Vaccination of neonates is generally difficult due to the immaturity of the immune system and consequent higher susceptibility to tolerance induction. Genetic immunization has been described as an alternative to trigger a stronger immune response in neonates, including significant Th1 polarization. In this investigation we analysed the potential use of a genetic vaccine containing the heat shock protein (hsp65) from Mycobacterium leprae (pVAXhsp65) against tuberculosis (TB) in neonate mice. Aspects as antigen production, genomic integration and immunogenicity were evaluated.

Methods

Hsp65 message and genomic integration were evaluated by RT-PCR and Southern blot, respectively. Immunogenicity of pVAXhsp65 alone or combined with BCG was analysed by specific induction of antibodies and cytokines, both quantified by ELISA.

Results

This DNA vaccine was transcribed by muscular cells of neonate mice without integration into the cellular genome. Even though this vaccine was not strongly immunogenic when entirely administered (three doses) during early animal's life, it was not tolerogenic. In addition, pVAXhsp65 and BCG were equally able to prime newborn mice for a strong and mixed immune response (Th1 + Th2) to pVAXhsp65 boosters administered later, at the adult life.

Conclusion

These results suggest that pVAXhsp65 can be safely used as a priming stimulus in neonate animals in prime-boost similar strategies to control TB. However, priming with BCG or pVAXhsp65, directed the ensuing immune response triggered by an heterologous or homologous booster, to a mixed Th1/Th2 pattern of response. Measures as introduction of IL-12 or GM-CSF genes in the vaccine construct or even IL-4 neutralization, are probably required to increase the priming towards Th1 polarization to ensure control of tuberculosis infection.