Quantification of regulatory T cells in septic patients by real-time PCR-based methylation assay and flow cytometry. PLoS One. 2012;7:e49962. [PMID: 23209626 PMCID: PMC3507919 DOI: 10.1371/journal.pone.0049962]

Th17/Treg balance: the bloom and wane in the pathophysiology of sepsis

Sepsis is a multi-organ dysfunction characterized by an unregulated host response to infection. It is associated with high morbidity, rapid disease progression, and high mortality. Current therapies mainly focus on symptomatic treatment, such as blood volume supplementation and antibiotic use, but their effectiveness is limited. Th17/Treg balance, based on its inflammatory property, plays a crucial role in determining the direction of the inflammatory response and the regression of organ damage in sepsis patients. This review provides a summary of the changes in T-helper (Th) 17 cell and regulatory T (Treg) cell differentiation and function during sepsis, the heterogeneity of Th17/Treg balance in the inflammatory response, and the relationship between Th17/Treg balance and organ damage. Th17/Treg balance exerts significant control over the bloom and wanes in host inflammatory response throughout sepsis.

Reduced Staphylococcus Abundance Characterizes the Lesional Microbiome of Actinic Keratosis Patients after Field-Directed Therapies

Skin microbiome dysbiosis with a Staphylococcus overabundance is a feature of actinic keratosis (AK) and squamous skin carcinoma (SCC) patients. The impact of lesion-directed treatments for AK lesions such as diclofenac (DIC) and cold atmospheric plasma (CAP) on the lesional microbiome is not established. We studied 321 skin microbiome samples of 59 AK patients treated with DIC 3% gel versus CAP. Microbial DNA from skin swabs taken before start of treatment (week 0), at the end of the treatment period (week 24), and 3 months after end of treatment (week 36) was analyzed after sequencing the V3/V4 region of the 16S rRNA gene. The relative abundance of S. aureus was scrutinized by a tuf gene specific TaqMan PCR assay. The total bacterial load and both, relative and absolute abundance of Staphylococcus genus was reduced upon both therapies at week 24 and 36 compared to week 0. Notably, the lesional microbiome of patients responding to CAP therapy at week 24 was characterized by an increased relative abundance of Corynebacterium genus compared to nonresponders. A higher relative abundance of Staphylococcus aureus at week 36 was a feature of patients classified as nonresponders for both treatments 12 weeks after therapy completion. The reduction of the Staphylococcus abundance after treatment of AK lesions and alterations linked to treatment response encourage further studies for investigation of the role of the skin microbiome for both, the carcinogenesis of epithelial skin cancer and its function as predictive therapeutic biomarker in AK. IMPORTANCE The relevance of the skin microbiome for development of actinic keratosis (AK), its progression into squamous skin cancer, and for field-directed treatment response is unknown. An overabundance of staphylococci characterizes the skin microbiome of AK lesions. In this study, analyses of the lesional microbiome from 321 samples of 59 AK patients treated with diclophenac gel versus cold atmospheric plasma (CAP) revealed a reduced total bacterial load and reduced relative and absolute Staphylococcus genus abundance upon both treatments. A higher relative Corynebacterium abundance was a feature of patients classified as responders at the end of CAP-treatment period (week 24) compared with nonresponders and the Staphylococcus aureus abundance of patients classified as responders 3 months after treatment completion was significantly lower than in nonresponders. The alterations of the skin microbiome upon AK treatment encourage further investigations for establishing its role for carcinogenesis and its function as predictive biomarker in AK.

Analysis of FOXP3 DNA Methylation Patterns to Identify Functional FOXP3+ T-Cell Subpopulations

Human regulatory CD4⁺CD25⁺FOXP3⁺ T cells (Tregs) are involved in the suppression of immune responses and play important roles in the maintenance of self-tolerance and immune homeostasis. Abnormal Treg function may result in disease states of varying severity. As FOXP3-expressing Treg cells are phenotypically and functionally heterogeneous, the success of Treg therapies depends on the ability to reliably distinguish subpopulations of T cells bearing a Treg-like phenotype. Methylation of cytosines within CpG dinucleotides is an important epigenetic mechanism involved in regulation (and suppression) of gene expression. On the other hand, demethylation of regulatory DNA sequences, such as promoters and enhancers, is essential for initiation of gene transcription. This protocol shows that bisulfite sequencing (BS) distinguishes methylated and unmethylated cytosines within DNA and reveals the methylation status of individual CpGs in cells within each population, identifying functionally different FOXP3⁺ subpopulations.

Distinct immunological and molecular signatures underpinning influenza vaccine responsiveness in the elderly

Seasonal influenza outbreaks, especially in high-risk groups such as the elderly, represent an important public health problem. Prevailing inadequate efficacy of seasonal vaccines is a crucial bottleneck. Understanding the immunological and molecular mechanisms underpinning differential influenza vaccine responsiveness is essential to improve vaccination strategies. Here we show comprehensive characterization of the immune response of randomly selected elderly participants (≥ 65 years), immunized with the adjuvanted influenza vaccine Fluad. In-depth analyses by serology, multi-parametric flow cytometry, multiplex and transcriptome analysis, coupled to bioinformatics and mathematical modelling, reveal distinguishing immunological and molecular features between responders and non-responders defined by vaccine-induced seroconversion. Non-responders are specifically characterized by multiple suppressive immune mechanisms. The generated comprehensive high dimensional dataset enables the identification of putative mechanisms and nodes responsible for vaccine non-responsiveness independently of confounding age-related effects, with the potential to facilitate development of tailored vaccination strategies for the elderly.

Circulating Treg cells expressing TNF receptor type 2 contributes to sepsis-induced immunosuppression in patients during sepsis shock

BACKGROUND

Septic shock remains a major cause of death that can be complicated by a long-term impairment in immune function defining immunosuppression induced by sepsis (IS). Among Treg cells, the tumor necrosis factor receptor 2 positive (TNFR2 pos) Treg cell subset endorses significant immunosuppressive functions in human tumors and in a sepsis mouse model but have not been investigated during septic shock in humans.

METHODS

We prospectively enrolled patients with septic shock hospitalized in Intensive Care Unit (ICU). We performed immunophenotyping and functional tests of CD4+T cells, Treg cells and TNFR2 posTregcells, on blood samples collected at 1, 4 and 7 days after admission in ICU.

RESULTS

We investigated 10 patients with septic shock and compared to 10 healthy controls. Although the proportions of circulating Tregcells and TNFR2 posTregcells subsets were not increased, their CTLA-4 expression and suppressive functions in vitro were increased at 4 days of septic shock. Also, PBMC from healthy donors cultured with serum from septic shock patients had increased CTLA4 expression in TNFR2 pos Treg cells compared to TNFR2 neg Treg cells.

CONCLUSION

In patients with septic shock, CTLA-4 expression and suppressive function were increased in circulating TNFR2 posTreg cells. We identify TNFR2 posTreg cells as a potential attractive target for therapeutic intervention.

Methylation-Sensitive Restriction Enzyme Quantitative Polymerase Chain Reaction Enables Rapid, Accurate, and Precise Detection of Methylation Status of the Regulatory T Cell (Treg)-Specific Demethylation Region in Primary Human Tregs

Human regulatory T cells (Tregs) have been implicated in cancer immunotherapy and are also an emerging cellular therapeutic for the treatment of multiple indications. Although Treg stability during ex vivo culture has improved, methods to assess Treg stability such as bisulfite Sanger sequencing to determine the methylation status of the Treg-specific demethylated region (TSDR) have remained unchanged. Bisulfite Sanger sequencing is not only costly and cumbersome to perform, it is inaccurate because of relatively low read counts. Bisulfite next-generation sequencing, although more accurate, is a less accessible method. In this study, we describe the application of methylation-sensitive restriction enzymes (MSRE) and quantitative PCR (qPCR) to determine the methylation status of the TSDR. Using known ratios of Tregs and non-Tregs, we show that MSRE-qPCR can distinguish the methylation status of the TSDR in populations of cells containing increasing proportions of Tregs from 0 to 100%. In a comparison with values obtained from an established bisulfite next-generation sequencing approach for determining the methylation status of the TSDR, our MSRE-qPCR results were within 5% on average for all samples with a high percentage (>70%) of Tregs, reinforcing that MSRE-qPCR can be completed in less time than other methods with the same level of accuracy. The value of this assay was further demonstrated by quantifying differences in TSDR methylation status of Tregs treated with and without rapamycin during an ex vivo expansion culture. Together, we show that our novel application of the MSRE-qPCR to the TSDR is an optimal assay for accurate assessment of Treg purity.

Role of the adaptive immune response in sepsis

Sepsis is a syndrome of shock and dysfunction of multiple vital organs that is caused by an uncontrolled immune response to infection and has a high mortality rate. There are no therapies for sepsis, and it has become a global cause for concern. Advances in patient care and management now mean that most patients survive the initial hyper-inflammatory phase of sepsis but progress to a later immunosuppressed phase, where 30% of patients die due to secondary infection. Deficits in the adaptive immune response may play a major role in sepsis patient mortality. The adaptive immune response involves a number of cell types including T cells, B cells and dendritic cells, all with immunoregulatory roles aimed at limiting damage and returning immune homeostasis after infection or insult. However, in sepsis, adaptive immune cells experience cell death or exhaustion, meaning that they have defective effector and memory responses ultimately resulting in an ineffective or suppressed immune defence. CD4+ T cells seem to be the most susceptible to cell death during sepsis and have ensuing defective secretory profiles and functions. Regulatory T cells seem to evade apoptosis and contribute to the immune suppression observed with sepsis. Preclinical studies have identified a number of new targets for therapy in sepsis including anti-apoptotic agents and monoclonal antibodies aimed at reducing cell death, exhaustion and maintaining/restoring adaptive immune cell functions. While early phase clinical trials have demonstrated safety and encouraging signals for biologic effect, larger scale clinical trial testing is required to determine whether these strategies will prove effective in improving outcomes from sepsis.

Molecular Markers Distinguishing T Cell Subtypes With TSDR Strand-Bias Methylation

Human regulatory CD4⁺CD25⁺FOXP3⁺ T cells (Treg) play important roles in the maintenance of self-tolerance and immune homeostasis in various disease settings and are also involved in the suppression of effective immune responses. These cells are heterogeneous in phenotype and function, and the ability to reliably distinguish between various FOXP3-expressing subpopulations can affect the development of successful therapies. This study demonstrates that hypomethylated CpG sites, present in four regions of the FOXP3 locus, CAMTA1 and FUT7 gene regions, can be used to distinguish several subsets of Treg from conventional CD4⁺ T lymphocytes (Tcon) in donors of both genders. We describe a previously unreported strand-bias hemimethylation pattern in FOXP3 promoter and TSDR in donors of both genders, with the coding strand being demethylated within promoter and methylated within TSDR in all CD4⁺ lymphocyte subtypes, whereas the template strand follows the previously described pattern of methylation with both regions being more demethylated in Treg subtypes and mostly methylated in Tcon. This strand-specific approach within the TSDR may prove to be instrumental in correctly defining Treg subsets in health and in disease.

Ulinastatin mediates suppression of regulatory T cells through TLR4/NF-κB signaling pathway in murine sepsis

CD4⁺CD25⁺ regulatory T cells (Tregs) play an essential role in the suppression of the immune response and prevention of autoimmune reactions. The activation of TLR4, which provides a critical link between the innate and adaptive immune systems, has been implicated in regulating the function of Tregs. Ulinastatin (UTI) is a broad-spectrum protease inhibitor that has been shown to modulate innate immunity and pro-inflammatory signaling in sepsis. In addition, there are reports that UTI may modulate the functional activity of Tregs to influence the inflammatory response in infectious disease. In the present study, we investigated the effect of UTI on the activity of Tregs, which was assessed by measuring the survival and inflammatory responses of mice with cecal ligation and puncture (CLP)-induced sepsis. In addition, we further explored the cellular and molecular mechanisms involved in these effects. The results showed that UTI could enhance survival and attenuate inflammatory responses during CLP-induced sepsis. Moreover, sepsis-induced increases in the quantity and activity of Tregs were attenuated under UTI treatment, but not in TLR4^-/- mice. We also found that the functional changes in Tregs could be attributed to the TLR4/NF-κB signaling pathway. Collectively, our results indicated that UTI could ameliorate inflammatory damage by modulating the quantity and function of Tregs via the TLR4/NF-κB signaling pathway. Our study provides theoretical and experimental evidence for the administration of UTI in the treatment of sepsis and other acute critical illnesses.

Toll-like receptor 4 deficiency increases resistance in sepsis-induced immune dysfunction

Sepsis constitutes a serious life-threatening syndrome associated with complications of deregulated inflammatory response against endotoxin/lipopolysaccharide (LPS)-mediated severe infection. Toll-like receptor 4 (TLR4) plays a critical role in the activation of innate immunity through recognition of LPS. However, the impact of TLR4 signaling on the development of sepsis-induced immune dysfunction remains unclear. The aim of this study was to investigate the effect of TLR4 on regulatory T cells (Tregs) and its potential mechanism. To simulate sepsis, male C57BL/6 (wild-type) and C57BL/10ScNJNJU (TLR4^-/-) mice were subjected to cecal ligation and puncture (CLP). After 24h, pro- and anti-inflammatory cytokine secretion, neutrophil and macrophage lung and liver infiltration were assessed to evaluate the sepsis-induced inflammatory response. The quantity and apoptotic rate of Tregs were measured. The expression of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and forkhead/winged helix transcription factor p3 (Foxp3) were analyzed. Cytokine (i.e., TNF-α, IL-2, IL-10, and IL-4) secretion by Tregs in the cell suspensions and the suppressive activity on CD4⁺CD25^- T cell proliferation were also determined in vitro. At 24h after the CLP procedure, the wild-type mice exhibited increased Treg levels and expression, and secreted inflammatory factors in the serum were markedly overproduced. However, the TLR4^-/- mice attenuated the increased Treg expression and inflammatory factor overproduction. These results indicate that in a model of post-septic mice, TLR4 deficiency improves immune paralysis by attenuating Treg activity and restoring a pro-inflammatory cytokine balance. Thus, modulation of the TLR4 activity may be useful in preventing immune dysfunction in sepsis.

Lymphocyte count as a sign of immunoparalysis and its correlation with nutritional status in pediatric intensive care patients with sepsis: A pilot study

OBJECTIVES:

Developing malnutrition during hospitalization is well recognized worldwide, and children are at a relatively higher risk for malnutrition than adults. Malnutrition can lead to immune dysfunction, which is associated with a higher mortality rate due to sepsis, the most frequent cause of death in pediatric intensive care units (PICUs). The aim of this study was to investigate whether malnourished patients are more likely to have relative or absolute lymphopenia and, consequently, worse prognoses.

METHODS:

We enrolled 14 consecutive patients with sepsis whose legal representatives provided written informed consent. Patients were classified as normal or malnourished based on anthropometric measurements. As an additional evaluation of nutritional status, serum albumin and zinc were measured on the 1st and 7th days of hospitalization. Lymphocyte count was also measured on the 1st and 7th days. Clinicaltrials.gov: NCT02698683.

RESULTS:

Malnutrition prevalence rates were 33.3% and 42.8% based on weight and height, respectively. Laboratory analyses revealed a reduction of serum albumin in 100% of patients and reduction of zinc in 93.3% of patients. A total of 35% of patients had fewer than 500 lymphocytes/mm3 on their first day in the PICU. Lymphocyte counts and zinc concentrations significantly increased during hospitalization.

CONCLUSIONS:

Nutritional evaluations, including anthropometric measurements, were not correlated with lymphocyte counts. Lymphocyte counts concomitantly increased with zinc levels, suggesting that micronutrient supplementation benefits patients with sepsis.

FOXP3+ Tregs: heterogeneous phenotypes and conflicting impacts on survival outcomes in patients with colorectal cancer

The tumor microenvironment composites a mixture of immune lymphoid cells, myeloid cells, stromal cells with complex cytokines, as well as numerous lymphovascular vessels. Colorectal cancer (CRC) is a common malignancy and one of the leading causes of tumor-related death in the United States and worldwide. The immune status in the tumor microenvironment contributes to the survival of a patient with CRC. Regulatory T cells (Tregs) are considered a key factor in immune escape and immunotherapy failure among cancer patients. The transcription factor forkhead box P3 (FOXP3) is a crucial intracellular marker and also a key developmental and functional factor for CD4+CD25+ Tregs. Tregs are correlated with survival in various human neoplasms, and elevated proportions of Tregs are usually associated with unfavorable clinical outcomes. However, the role of Tregs in CRC remains controversial. High densities of tumor-infiltrating Tregs in CRC patients are reported to be correlated with worse or better outcomes. And Tregs may not be predictive of prognosis after resection of the primary tumor. The exact explanations for these discordant results remain unclear. The heterogeneous instincts of cell phenotype, gene expression, and functional activities of Tregs may partly contribute this contrasting result. Furthermore, the lack of a robust marker for identifying Tregs or due to the different techniques applied is also account. The Treg-specific demethylated region (TSDR) was recently reported to be a specific epigenetic marker for natural Tregs (nTregs), which can stably express FOXP3. The FOXP3-TSDR demethylation assay may be an promising technique for CRC-related nTregs studies.

Relevance of Foxp3⁺ regulatory T cells for early and late phases of murine sepsis

The role of Foxp3(+) regulatory T (Treg) cells in the course of the early hyper-inflammatory and subsequent hypo-inflammatory phases of sepsis is ambiguous. Whereas Nrp1 expression has been reported to discriminate natural Treg cells from induced Treg cells, the Treg cell stability depends on the methylation status of foxp3-TSDR. To specifically evaluate the role of Foxp3(+) Treg cells in the early and late phases of sepsis, we induced sepsis by caecal ligation and puncture and subsequent Pseudomonas aeruginosa lung infection in a DEREG (DEpletion of REGulatory T cells) mouse model. We found an increase of Foxp3(+) Treg cells to all CD4(+) T cells during murine sepsis. Using a new methylation-sensitive quantitative RT-PCR method and deep amplicon sequencing, we demonstrated that natural (Nrp1(+) Foxp3(+) ) Treg cells and most induced (Nrp1(-) Foxp3(+) ) Treg cells are stable and exhibit unmethylated foxp3-TSDR, and that both Treg populations are functionally suppressive in healthy and septic mice. DEREG mice depleted of Foxp3(+) Treg cells exhibit higher disease scores, mortality rates and interleukin-6 expression levels than do non-depleted DEREG mice in early-phase sepsis, a finding indicating that Foxp3(+) Treg cells limit the hyper-inflammatory response and accelerate recovery. Treg cell depletion before secondary infection with P. aeruginosa 1 week after caecal ligation and puncture does not influence cytokine levels or the course of secondary infection. However, a moderate Treg cell recurrence, which we observed in DEREG mice during secondary infection, may interfere with these results. In summary, Treg cells contribute to a positive outcome after early-phase sepsis, but the data do not support a significant role of Treg cells in immune paralysis during late-phase sepsis.

A comparison of DNA methylation specific droplet digital PCR (ddPCR) and real time qPCR with flow cytometry in characterizing human T cells in peripheral blood

Quantitating the copy number of demethylated CpG promoter sites of the CD3Z gene can be used to estimate the numbers and proportions of T cells in human blood and tissue. Quantitative methylation specific PCR (qPCR) is useful for studying T cells but requires extensive calibration and is imprecise at low copy numbers. Here we compared the performance of a new digital PCR platform (droplet digital PCR or ddPCR) to qPCR using bisulfite converted DNA from 157 blood specimens obtained from ambulatory care controls and patients with primary glioma. We compared both ddPCR and qPCR with conventional flow cytometry (FACS) evaluation of CD3 positive T cells. Repeated measures on the same blood sample revealed ddPCR to be less variable than qPCR. Both qPCR and ddPCR correlated significantly with FACS evaluation of peripheral blood CD3 counts and CD3/total leukocyte values. However, statistical measures of agreement showed that linear concordance was stronger for ddPCR than for qPCR and the absolute values were closer to FACS for ddPCR. Both qPCR and ddPCR could distinguish clinically significant differences in T cell proportions and performed similarly to FACS. Given the higher precision, greater accuracy, and technical simplicity of ddPCR, this approach appears to be a superior DNA methylation based method than conventional qPCR for the assessment of T cells.

Lack of correlation between Treg quantification assays in inflammatory bowel disease patients

AIM: To compare the number of regulatory T-cells (Tregs) measured by flow cytometry with those obtained using a real-time quantitative PCR (qPCR) method in patients suffering from inflammatory bowel disease (IBD).

METHODS: Tregs percentages obtained by both flow cytometry and qPCR methods in 35 adult IBD patients, 18 out of them with Crohn´s disease (CD) and 17 with ulcerative colitis (UC) were compared to each other as well as to scores on two IBD activity questionnaires using the Harvey Bradshaw Index (HBI) for CD patients and the Simple Colitis Clinical Activity Index (SCCAI) for UC patients. The Treg percentages by flow cytometry were defined as CD4⁺CD25^highCD127^lowFOXP3⁺ cells in peripheral blood mononuclear cells, whereas the Treg percentages by qPCR method were determined as FOXP3 promoter demethylation in genomic DNA.

RESULTS: We found an average of 1.56% ± 0.78% Tregs by using flow cytometry, compared to 1.07% ± 0.53% Tregs by using qPCR in adult IBD patients. There were no significant correlations between either the percentages of Tregs measured by flow cytometry or qPCR and the HBI or SCCAI questionnaire scores in CD or UC patients, respectively. In addition, there was no correlation between Treg percentages measured by qPCR and those measured by flow cytometry (r = -0.06, P = 0.73; Spearman Rho). These data suggest that, either Treg-related immune function or the clinical scores in these IBD patients did not accurately reflect actual disease activity. Until the cause(s) for these differences are more clearly defined, the results suggest caution in interpreting studies of Tregs in various inflammatory disorders.

CONCLUSION: The two methods did not produce equivalent measures of the percentage of total Tregs in the IBD patients studied which is consistent with the conclusion that Tregs subtypes are not equally detected by these two assays.

The effects of CCR5 inhibition on regulatory T-cell recruitment to colorectal cancer

BACKGROUND

Regulatory T cells (Treg) are enriched in human colorectal cancer (CRC) where they suppress anti-tumour immunity. The chemokine receptor CCR5 has been implicated in the recruitment of Treg from blood into CRC and tumour growth is delayed in CCR5-/- mice, associated with reduced tumour Treg infiltration.

METHODS

Tissue and blood samples were obtained from patients undergoing resection of CRC. Tumour-infiltrating lymphocytes were phenotyped for chemokine receptors using flow cytometry. The presence of tissue chemokines was assessed. Standard chemotaxis and suppression assays were performed and the effects of CCR5 blockade were tested in murine tumour models.

RESULTS

Functional CCR5 was highly expressed by human CRC infiltrating Treg and CCR5(high) Treg were more suppressive than their CCR5(low) Treg counterparts. Human CRC-Treg were more proliferative and activated than other T cells suggesting that local proliferation could provide an alternative explanation for the observed tumour Treg enrichment. Pharmacological inhibition of CCR5 failed to reduce tumour Treg infiltration in murine tumour models although it did result in delayed tumour growth.

CONCLUSIONS

CCR5 inhibition does not mediate anti-tumour effects as a consequence of inhibiting Treg recruitment. Other mechanisms must be found to explain this effect. This has important implications for anti-CCR5 therapy in CRC.

Impact of sepsis on CD4 T cell immunity

Sepsis remains the primary cause of death from infection in hospital patients, despite improvements in antibiotics and intensive-care practices. Patients who survive severe sepsis can display suppressed immune function, often manifested as an increased susceptibility to (and mortality from) nosocomial infections. Not only is there a significant reduction in the number of various immune cell populations during sepsis, but there is also decreased function in the remaining lymphocytes. Within the immune system, CD4 T cells are important players in the proper development of numerous cellular and humoral immune responses. Despite sufficient clinical evidence of CD4 T cell loss in septic patients of all ages, the impact of sepsis on CD4 T cell responses is not well understood. Recent findings suggest that CD4 T cell impairment is a multipronged problem that results from initial sepsis-induced cell loss. However, the subsequent lymphopenia-induced numerical recovery of the CD4 T cell compartment leads to intrinsic alterations in phenotype and effector function, reduced repertoire diversity, changes in the composition of naive antigen-specific CD4 T cell pools, and changes in the representation of different CD4 T cell subpopulations (e.g., increases in Treg frequency). This review focuses on sepsis-induced alterations within the CD4 T cell compartment that influence the ability of the immune system to control secondary heterologous infections. The understanding of how sepsis affects CD4 T cells through their numerical loss and recovery, as well as function, is important in the development of future treatments designed to restore CD4 T cells to their presepsis state.

Impact of 5-aza-2'-deoxycytidine and epigallocatechin-3-gallate for induction of human regulatory T cells

The epigenetic regulation of transcription factor genes is critical for T-cell lineage specification. A specific methylation pattern within a conserved region of the lineage specifying transcription factor gene FOXP3, the Treg-specific demethylated region (TSDR), is restricted to regulatory T (Treg) cells and is required for stable expression of FOXP3 and suppressive function. We analysed the impact of hypomethylating agents 5-aza-2'-deoxycytidine and epigallocatechin-3-gallate on human CD4(+)  CD25(-) T cells for generating demethylation within FOXP3-TSDR and inducing functional Treg cells. Gene expression, including lineage-specifying transcription factors of the major T-cell lineages and their leading cytokines, functional properties and global transcriptome changes were analysed. The FOXP3-TSDR methylation pattern was determined by using deep amplicon bisulphite sequencing. 5-aza-2'-deoxycytidine induced FOXP3-TSDR hypomethylation and expression of the Treg-cell-specific genes FOXP3 and LRRC32. Proliferation of 5-aza-2'-deoxycytidine-treated cells was reduced, but the cells did not show suppressive function. Hypomethylation was not restricted to FOXP3-TSDR and expression of master transcription factors and leading cytokines of T helper type 1 and type 17 cells were induced. Epigallocatechin-3-gallate induced global DNA hypomethylation to a lesser extent than 5-aza-2'-deoxycitidine, but no relevant hypomethylation within FOXP3-TSDR or expression of Treg-cell-specific genes. Neither of the DNA methyltransferase inhibitors induced fully functional human Treg cells. 5-aza-2'-deoxycitidine-treated cells resembled Treg cells, but they did not suppress proliferation of responder cells, which is an essential capability to be used for Treg cell transfer therapy. Using a recently developed targeted demethylation technology might be a more promising approach for the generation of functional Treg cells.

A novel upstream enhancer of FOXP3, sensitive to methylation-induced silencing, exhibits dysregulated methylation in rheumatoid arthritis Treg cells

Treg-cell function is compromised in rheumatoid arthritis (RA). As the master regulator of Treg cells, FOXP3 controls development and suppressive function. Stable Treg-cell FOXP3 expression is epigenetically regulated; constitutive expression requires a demethylated Treg-specific demethylated region. Here, we hypothesised that methylation of the FOXP3 locus is altered in Treg cells of established RA patients. Methylation analysis of key regulatory regions in the FOXP3 locus was performed on Treg cells from RA patients and healthy controls. The FOXP3 Treg-specific demethylated region and proximal promoter displayed comparable methylation profiles in RA and healthy-donor Treg cells. We identified a novel differentially methylated region (DMR) upstream of the FOXP3 promoter, with enhancer activity sensitive to methylation-induced silencing. In RA Treg cells we observed significantly reduced DMR methylation and lower DNA methyltransferase (DNMT1/3A) expression compared with healthy Treg cells. Furthermore, DMR methylation negatively correlated with FOXP3 mRNA expression, and Treg cells isolated from rheumatoid factor negative RA patients were found to express significantly higher levels of FOXP3 than Treg cells from RhF-positive patients, with an associated decrease in DMR methylation. In conclusion, the novel DMR is involved in the regulation of Treg-cell FOXP3 expression, but this regulation is lost post-transcriptionally in RA Treg cells.

A method for conducting suppression assays using small numbers of tissue-isolated regulatory T cells

The suppression assay is a commonly performed assay, measuring the ability of regulatory T cells (Treg) to suppress T cell proliferation. Most frequently, Treg are obtained from the peripheral blood or spleen. Lower yields are obtained by isolation from other tissues, rendering downstream suppression assays challenging to perform. Furthermore, the importance of suppressive subpopulations of Treg favours their isolation by fluorescent-activated cell sorting. Here we describe a method to isolate Treg from human tissues, using colorectal cancer tissue as an example. Treg suppressive capacity was further examined by expression of CCR5 to demonstrate the ability of our method to assess the suppressive capacity of regulatory T cell subsets.

To optimise the standard suppression assay to achieve our research aims, the following modifications were made:•

Treg, isolated from tissues, were sorted directly into a well-plate.

•

Responder T cells, which had been fluorescently-labelled prior to sorting, were added directly into the well-plate.

•

Human Treg Suppression Inspector beads (Miltenyi Biotec Ltd., UK) provided a polyclonal stimulus for proliferation and were added to each well at a bead:lymphocyte ratio of 1:2.

This method quantified the suppression of responder T cell proliferation by small numbers of strictly-defined Treg populations isolated from tissues.

Noncanonical Nuclear Factor Kappa B (NF-κB) Signaling and Potential for Therapeutics in Sepsis

NF-κB signaling plays a central role in the pathophysiology of severe sepsis and septic shock. Despite tremendous and missed efforts, novel therapeutics for severe sepsis and septic shock are still needed. Many drugs have been designed to target the canonical NF-κB signaling pathway with limited success, potentially due to the nonspecificity of the drugs for other kinases and the interaction of canonical signaling with other pathways. Here, we review the canonical and noncanonical signaling pathways of NF-κB, the cross talk and negative regulation of the two pathways, and the potential for therapeutics arising from the noncanonical NF-κB pathway in relation to the pathophysiology of septic shock.

The significance and regulatory mechanisms of innate immune cells in the development of sepsis

Sepsis with subsequent multiple organ dysfunction is a pronounced systemic inflammatory response to concealed or known infection and is a leading cause of death in intensive care units. The survival rate of severe sepsis and septic shock has not markedly improved in recent decades despite a great number of receptors and molecules involved in its pathogenesis have been found and taken as therapeutic targets. It is essential to thoroughly understand the host cell-mediated immunity involved in the development of sepsis and sepsis-related organ injury. Recent studies indicate that innate immune cells (such as neutrophils, macrophages, dendritic cells, T lymphocytes, regulatory T cells, and natural killer T cells) play pivotal roles in the maintenance of peripheral homeostasis and regulation of immune responses during sepsis. Therefore, an understanding of the biological significance and pathophysiological roles of different cell populations might gain novel insights into the immunoregulatory mechanisms of sepsis. In this review, we focus on major immune cells that may play potential roles in the contribution of new therapeutic approaches for sepsis.