Epigenetic modification of the FoxP3 TSDR in HAM/TSP decreases the functional suppression of Tregs

Extracellular vesicles in the pathogenesis of neurotropic viruses

Neurotropic viruses, characterized by their capacity to invade the central nervous system, present a considerable challenge to public health and are responsible for a diverse range of neurological disorders. This group includes a diverse array of viruses, such as herpes simplex virus, varicella zoster virus, poliovirus, enterovirus and Japanese encephalitis virus, among others. Some of these viruses exhibit high neuroinvasiveness and neurovirulence, while others demonstrate weaker neuroinvasive and neurovirulent properties. The clinical manifestations of infections caused by neurotropic viruses can vary significantly, ranging from mild symptoms to severe life-threatening conditions. Extracellular vesicles (EVs) have garnered considerable attention due to their pivotal role in intracellular communication, which modulates the biological activity of target cells via the transport of biomolecules in both health and disease. Investigating EVs in the context of virus infection is crucial for elucidating their potential role contribution to viral pathogenesis. This is because EVs derived from virus-infected cells frequently transfer viral components to uninfected cells. Importantly, EVs released by virus-infected cells have the capacity to traverse the blood-brain barrier (BBB), thereby impacting neuronal activity and inducing neuroinflammation. In this review, we explore the roles of EVs during neurotropic virus infections in either enhancing or inhibiting viral pathogenesis. We will delve into our current comprehension of the molecular mechanisms that underpin these roles, the potential implications for the infected host, and the prospective diagnostic applications that could arise from this understanding.

The contribution of neuropilin-1 in the stability of CD4+ CD25+ regulatory T cells through the TGF-β1/Smads signaling pathway in the presence of lipopolysaccharides

Introduction

This study investigates the synergistic effect of TGF‐β1 and Nrp‐1 on CD4⁺CD25⁺ T_regs' stabilization, and the associated pathways of signal transduction, in vitro models in the presence of LPS.

Materials and Methods

Spleen CD4⁺CD25⁺ T_regs cells of mice models in the presence of LPS, were transfected with an shRNA targeting Nrp‐1, Smad2, or Smad3, may or may not be treated with recombinant TGF‐β1. Followed by subsequent determination of cellular proliferation, rate of apoptosis, observation of the Foxp3, CTLA‐4, and TGF‐β1^m+ expression levels, foxp3‐TSDR methylation, secretion levels of the inhibitory cytokines IL‐10 and TGF‐β1, and Smad2/3 of CD4⁺CD25⁺ T_regs expression.

Results

A remarkable stimulation in CD4⁺CD25⁺ T_regs' stability is noted after administering recombinant TGF‐β1 in the presence of LPS, and promoted cellular viability, increased Foxp3, CTLA‐4, and TGF‐β1^m+ expression, and elevated secretion of IL‐10 and TGF‐β1. This also inhibited the apoptosis and methylation of foxp3‐ TSDR of CD4⁺CD25⁺ T_regs. The shRNA transfection silenced Nrp‐1 and Smad3, but not Smad2, resulting in the suppression of the recombinant TGF‐β1‐mediated effects in the presence of LPS.

Conclusions

According to the results, Nrp‐1 mediates TGF‐β1 to improve the stability of regulatory CD4⁺CD25⁺ T cells and maybe a possible therapeutic target with the ability to improve the CD4⁺CD25⁺ T_regs associated negative immunoregulation that is related to the TGF‐β1/Smads cell signaling during sepsis.

Safety, tolerability, and immune-biomarker profiling for year-long sargramostim treatment of Parkinson's disease

Background

Neuroinflammation plays a pathogenic role in Parkinson's disease (PD). Immunotherapies that restore brain homeostasis can mitigate neurodegeneration by transforming T cell phenotypes. Sargramostim has gained considerable attention as an immune transformer through laboratory bench to bedside clinical studies. However, its therapeutic use has been offset by dose-dependent adverse events. Therefore, we performed a reduced drug dose regimen to evaluate safety and to uncover novel disease-linked biomarkers during 5 days/week sargramostim treatments for one year.

Methods

Five PD subjects were enrolled in a Phase 1b, unblinded, open-label study to assess safety and tolerability of 3 μg/kg/day sargramostim. Complete blood counts and chemistry profiles, physical examinations, adverse events (AEs), immune profiling, Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) scores, T cell phenotypes/function, DNA methylation, and gene and protein patterns were evaluated.

Findings

Sargramostim administered at 3 μg/kg/day significantly reduced numbers and severity of AEs/subject/month compared to 6 μg/kg/day treatment. While MDS-UPDRS Part III score reductions were recorded, peripheral blood immunoregulatory phenotypes and function were elevated. Hypomethylation of upstream FOXP3 DNA elements was also increased.

Interpretation

Long-term sargramostim treatment at 3 μg/kg/day is well-tolerated and effective in restoring immune homeostasis. There were decreased numbers and severity of AEs and restored peripheral immune function coordinate with increased numbers and function of Treg. MDS-UPDRS Part III scores did not worsen. Larger patient numbers need be evaluated to assess conclusive drug efficacy (ClinicalTrials.gov NCT03790670).

Funding

The research was supported by community funds to the University of Nebraska Foundation and federal research support from 5 R01NS034239-25.

Targeting Neuropilin-1 Suppresses the Stability of CD4+ CD25+ Regulatory T Cells via the NF-κB Signaling Pathway in Sepsis

Neuropilin-1 (Nrp-1) contributes to maintaining the stability of CD4⁺ CD25⁺ regulatory T cells (T_regs). We investigated the impact of Nrp-1 on the stability of CD4⁺ CD25⁺ T_regs, and the underlying signaling pathways, in a model of sepsis. Splenic CD4⁺ CD25⁺ T_regs were either treated with anti-Nrp-1, transfected to silence Nrp-1 and inhibitor of NF-κB kinase subunit beta (IKKβ), or administered ammonium pyrrolidine dithiocarbamate (PDTC), followed by recombinant semaphorin 3A (rSema3A), in a simulation of sepsis. After the creation of a sepsis model in mice, anti-Nrp-1 was administered. The expression of the gene encoding forkhead box protein P-3 foxp3-T_reg-specific demethylated region (foxp3-TSDR), the apoptosis rate, the expression of Foxp-3, cytotoxic T-lymphocyte-associated protein-4 (CTLA-4), and transforming growth factor β1 (TGF-β1), interleukin 10 (IL-10) and TGF-β1 secretion, and the NF-κB signaling activity of CD4⁺ CD25⁺ T_regs were determined. Sepsis simulation with or without rSema3A increased the stability of CD4⁺ CD25⁺ T_regs, including an increase in the expression of Foxp-3, CTLA-4, and TGF-β1, decreases in apoptosis and the methylation of foxp3-TSDR, increases in the secretion of TGF-β1 and IL-10, and an increase in the immunosuppressive effect on CD4⁺ T lymphocytes. Silencing of Nrp-1 or anti-Nrp-1 treatment abrogated lipopolysaccharide (LPS) stimulation with or without an rSema3A-mediated effect. Sepsis simulation increased the DNA-binding activity of NF-κB, as well as the ratios of phosphorylated IKKβ (p-IKKβ) to IKKβ and p-P65 to P65 in vitro and vivo Silencing of IKKβ expression or PDTC treatment suppressed the stability of CD4⁺ CD25⁺ T_regs in LPS-induced sepsis. Weakening Nrp-1 reduced the stability of CD4⁺ CD25⁺ T_regs by regulating the NF-κB signaling pathway; thus, Nrp-1 could be a new target for immunoregulation in sepsis.

The versatile role of exosomes in human retroviral infections: from immunopathogenesis to clinical application

Eukaryotic cells produce extracellular vesicles (EVs) mediating intercellular communication. These vesicles encompass many bio-molecules such as proteins, nucleic acids, and lipids that are transported between cells and regulate pathophysiological actions in the recipient cell. Exosomes originate from multivesicular bodies inside cells and microvesicles shed from the plasma membrane and participate in various pathological conditions. Retroviruses such as Human Immunodeficiency Virus -type 1 (HIV-1) and Human T-cell leukemia virus (HTLV)-1 engage exosomes for spreading and infection. Exosomes from virus-infected cells transfer viral components such as miRNAs and proteins that promote infection and inflammation. Additionally, these exosomes deliver virus receptors to target cells that make them susceptible to virus entry. HIV-1 infected cells release exosomes that contribute to the pathogenesis including neurological disorders and malignancy. Exosomes can also potentially carry out as a modern approach for the development of HIV-1 and HTLV-1 vaccines. Furthermore, as exosomes are present in most biological fluids, they hold the supreme capacity for clinical usage in the early diagnosis and prognosis of viral infection and associated diseases. Our current knowledge of exosomes' role from virus-infected cells may provide an avenue for efficient retroviruses associated with disease prevention. However, the exact mechanism involved in retroviruses infection/ inflammation remains elusive and related exosomes research will shed light on the mechanisms of pathogenesis.

Decipher manifestations and Treg /Th17 imbalance in multi-staging rheumatoid arthritis and correlation with TSDR/RORC methylation

T regulatory (Treg)/T-helper (Th) 17 imbalance has been shown to integrate with epigenetics to result in the development of autoimmune diseases. We aim to investigate the influence of disease staging on Treg/Th17 cells and whether the aberrant DNA methylation is implicated in the development of rheumatoid arthritis (RA). By recruiting 65 patients with multi-staging RA and 20 healthy controls (HC), we found that patients with active RA exhibited relative lymphopenia and higher WBC, neutrophils, and PLT. Circulating Treg/Th17 in patients with early active RA was significantly decreased. The expression of IL-6 and IL-17A was significantly increased in early active RA, whereas that of IL-10 and TGF-β was on the contrary. Furthermore, the frequency of Treg cells and Treg/Th17 were negatively correlated with DAS28, and the frequency of Th17 cells was on the contrary. Levels of DNA methylation related enzymes had significant difference between early active RA and HC. Relative hypermethylation was observed at the gene level for Treg-specific demethylated region (TSDR) and hypomethylation for retinoic acid-related orphan receptor (ROR)-C in early active RA. Thus, manifestations of RA and Treg/Th17 imbalance vary with disease staging, and the aberrant DNA methylation pattern may contribute to RA disease pathogenesis. Our results highlight the importance of disease staging in clinical research.

The emerging role of epigenetics in the immune response to vaccination and infection: a systematic review

Extensive research has highlighted the role of infection-induced epigenetic events in the development of cancer. More recently, attention has focused on the ability of non-carcinogenic infections, as well as vaccines, to modify the human epigenome and modulate the immune response. This review explores this rapidly evolving area of investigation and outlines the many and varied ways in which vaccination and natural infection can influence the human epigenome from modulation of the innate and adaptive immune response, to biological ageing and modification of disease risk. The implications of these epigenetic changes on immune regulation and their potential application to the diagnosis and treatment of chronic infection and vaccine development are also discussed.

EOS, an Ikaros family zinc finger transcription factor, interacts with the HTLV-1 oncoprotein Tax and is downregulated in peripheral blood mononuclear cells of HTLV-1-infected individuals, irrespective of clinical statuses

BACKGROUND

EOS plays an important role in maintaining the suppressive function of regulatory T cells (Tregs), and induces a regulated transformation of Tregs into T helper-like cells, which are capable of secreting proinflammatory cytokines in response to specific inflammatory signals. Meanwhile, significant reduction in Treg activity along with production of proinflammatory cytokines has been reported in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP).

METHODS

In this study, to examine whether there is an alteration in EOS expression in peripheral blood mononuclear cells (PBMCs) derived from HTLV-1-infected individuals especially HAM/TSP, we investigated the expression of HTLV-1 tax genotype, proviral load (PVL), and the mRNA expression of tax, HBZ and EOS in HTLV-1 infected individuals including adult T-cell leukemia/lymphoma (ATL), HAM/TSP, or asymptomatic carriers. The expression levels of EOS mRNA and protein in various HTLV-1-infected or uninfected human T-cell lines were also investigated.

RESULTS

EOS was highly expressed at the protein level in most HTLV-1 infected T-cell lines, and was augmented after the HTLV-1 regulatory factor Tax was induced in a Tax-inducible JPX-9 cell line. Immunoprecipitation experiments demonstrated a physical interaction between EOS and the viral regulatory protein Tax, but not HBZ. Meanwhile, there was a significant decrease in EOS mRNA levels in PBMCs of HTLV-1 infected individuals irrespective of their clinical statuses. We found an inverse correlation between EOS mRNA levels and HTLV-1 PVL in ATL patients, and positive correlations between both EOS mRNA load and PVL, and EOS and HBZ mRNA load in HAM/TSP patients, whereas this correlation was not observed in other clinical statuses.

CONCLUSIONS

These findings suggest that both Tax and HBZ can alter the expression of EOS through undetermined mechanisms, and dysregulated expression of EOS in PBMCs of HTLV-1 infected individuals may contribute to the pathological progression of HTLV-1-associated diseases, such as ATL and HAM/TSP.

Immunovirological markers in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP)

Human T cell lymphotropic virus 1 (HTLV-1) is a human retrovirus and infects approximately 10–20 million people worldwide. While the majority of infected people are asymptomatic carriers of HTLV-1, only 4% of infected people develop HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HAM/TSP is a chronic, progressive, neurological disease which usually progresses slowly without remission, and is characterized by perivascular inflammatory infiltrates in chronic inflammatory lesions of the central nervous system (CNS), primarily affecting the spinal cord. A high HTLV-1 proviral load, high levels of antibodies against HTLV-1 antigens, and elevated concentration of proteins are detected in cerebrospinal fluid (CSF) of HAM/TSP patients. These chronically activated immune responses against HTLV-1 and infiltration of inflammatory cells including HTLV-1 infected cells into the CNS contribute to clinical disability and underlie the pathogenesis of HAM/TSP. Since the disease development of HAM/TSP mainly occurs in adults, with a mean age at onset of 40–50 years, it is important for HTLV-1-infected carriers and HAM/TSP patients to be monitored throughout the disease process. Recent advances in technologies and findings provide new insights to virological and immunological aspects in both the CNS as well as in peripheral blood. In this review, we focus on understanding the inflammatory milieu in the CNS and discuss the immunopathogenic process in HTLV-1-associated neurologic diseases.

Semaphorin 4A Stabilizes Human Regulatory T Cell Phenotype via Plexin B1

We previously reported that neuroimmune semaphorin (Sema) 4A regulates the severity of experimental allergic asthma and increases regulatory T (Treg) cell numbers in vivo; however, the mechanisms of Sema4A action remain unknown. It was also reported that Sema4A controls murine Treg cell function and survival acting through neuropilin 1 (NRP-1) receptor. To clarify Sema4A action on human T cells, we employed T cell lines (HuT78 and HuT102), human PBMCs, and CD4+ T cells in phenotypic and functional assays. We found that HuT78 demonstrated a T effector-like phenotype (CD4+CD25lowFoxp3-), whereas HuT102 expressed a Treg-like phenotype (CD4+CD25hi Foxp3+). Neither cell line expressed NRP-1. HuT102 cells expressed Sema4A counter receptor Plexin B1, whereas HuT78 cells were Sema4A+. All human peripheral blood CD4+ T cells, including Treg cells, expressed PlexinB1 and lacked both NRP-1 and -2. However, NRP-1 and Sema4A were detected on CD3negativeCD4intermediate human monocytes. Culture of HuT cells with soluble Sema4A led to an upregulation of CD25 and Foxp3 markers on HuT102 cells. Addition of Sema4A increased the relative numbers of CD4+CD25+Foxp3+ cells in PBMCs and CD4+ T cells, which were NRP-1negative but PlexinB1+, suggesting the role of this receptor in Treg cell stability. The inclusion of anti-PlexinB1 blocking Ab in cultures before recombinant Sema4A addition significantly decreased Treg cell numbers as compared with cultures with recombinant Sema4A alone. Sema4A was as effective as TGF-β in inducible Treg cell induction from CD4+CD25depleted cells but did not enhance Treg cell suppressive activity in vitro. These results suggest strategies for the development of new Sema4A-based therapeutic measures to combat allergic inflammatory diseases. ImmunoHorizons, 2019, 3: 71-87.

Viral antigens detectable in CSF exosomes from patients with retrovirus associated neurologic disease: functional role of exosomes

BACKGROUND

HTLV-1 infects over 20 million people worldwide and causes a progressive neuroinflammatory disorder in a subset of infected individuals called HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). The detection of HTLV-1 specific T cells in the cerebrospinal fluid (CSF) suggests this disease is immunopathologically mediated and that it may be driven by viral antigens. Exosomes are microvesicles originating from the endosomal compartment that are shed into the extracellular space by various cell types. It is now understood that several viruses take advantage of this mode of intercellular communication for packaging of viral components as well. We sought to understand if this is the case in HTLV-1 infection, and specifically if HTLV-1 proteins can be found in the CSF of HAM/TSP patients where we know free virus is absent, and furthermore, if exosomes containing HTLV-1 Tax have functional consequences.

RESULTS

Exosomes that were positive for HTLV-1 Tax by Western blot were isolated from HAM/TSP patient PBMCs (25/36) in ex vivo cultures by trapping exosomes from culture supernatants. HTLV-1 seronegative PBMCs did not have exosomes with Tax (0/12), (Fisher exact test, p = 0.0001). We were able to observe HAM/TSP patient CSF (12/20) containing Tax⁺ exosomes but not in HTLV-1 seronegative MS donors (0/5), despite the absence of viral detection in the CSF supernatant (Fisher exact test p = 0.0391). Furthermore, exosomes cultivated from HAM/TSP PBMCs were capable of sensitizing target cells for HTLV-1 specific CTL lysis.

CONCLUSION

Cumulatively, these results show that there are HTLV-1 proteins present in exosomes found in virus-free CSF. HAM/TSP PBMCs, particularly CD4⁺CD25⁺ T cells, can excrete these exosomes containing HTLV-1 Tax and may be a source of the exosomes found in patient CSF. Importantly, these exosomes are capable of sensitizing an HTLV-1 specific immune response, suggesting that they may play a role in the immunopathology observed in HAM/TSP. Given the infiltration of HTLV-1 Tax-specific CTLs into the CNS of HAM/TSP patients, it is likely that exosomes may also contribute to the continuous activation and inflammation observed in HAM/TSP, and may suggest future targeted therapies in this disorder.

Emerging therapeutic biomarkers of autoimmune hepatitis and their impact on current and future management

Autoimmune hepatitis lacks a quantifiable biomarker that is close to its pathogenic mechanisms and that accurately reflects inflammatory activity, correlates with treatment response, and ensures inactive disease before treatment withdrawal. Areas covered: Micro-ribonucleic acids, programmed death-1 protein and its ligands, macrophage migration inhibitory factor, soluble CD163, B cell activating factor, and metabolite patterns in blood were considered the leading candidates as therapeutic biomarkers after search of PubMed from August 1981 to August 2017 using the search words 'biomarkers of autoimmune hepatitis'. Expert commentary: Each of the candidate biomarkers is close to the putative pathogenic mechanisms of autoimmune hepatitis, and each has attributes that support its potential role as a surrogate marker of inflammatory activity that can be monitored during treatment. Future studies must demonstrate the superiority of each biomarker to conventional indices of inflammatory activity and validate their correlation with treatment response and outcome. A reliable therapeutic biomarker would facilitate the individualization of current management algorithms, ensure that pathogenic mechanisms were disrupted or eliminated prior to treatment withdrawal, and reduce the frequency of relapse or unnecessary protracted therapy. The biomarker might also prove to be a target of next-generation therapies.

Role of Exosomes in Human Retroviral Mediated Disorders

Retroviruses comprise an ancient and varied group of viruses with the unique ability to integrate DNA from an RNA transcript into the genome, a subset of which are able to integrate in humans. The timing of these integrations during human history has dictated whether these viruses have remained exogenous and given rise to various human diseases or have become inseparable from the host genome (endogenous retroviruses). Given the ability of retroviruses to integrate into the host and subsequently co-opt host cellular process for viral propagation, retroviruses have been shown to be closely associated with several cellular processes including exosome formation. Exosomes are 30-150 nm unilamellar extracellular vesicles that originate from intraluminal vesicles (ILVs) that form in the endosomal compartment. Exosomes have been shown to be important in intercellular communication and immune cell function. Almost every cell type studied has been shown to produce these types of vesicles, with the cell type dictating the contents, which include proteins, mRNA, and miRNAs. Importantly, recent evidence has shown that infection by viruses, including retroviruses, alter the contents and subsequent function of produced exosomes. In this review, we will discuss the important retroviruses associated with human health and disease. Furthermore, we will delve into the impact of exosome formation and manipulation by integrated retroviruses on human health, survival, and human retroviral disease pathogenesis.

Epigenetic changes and their implications in autoimmune hepatitis

BACKGROUND

The genetic risk of autoimmune hepatitis is insufficient to explain the observed risk, and epigenetic changes may explain disparities in disease occurrence in different populations within and between countries. The goal of this review was to examine how epigenetic changes induced by the environment or inherited as a phenotypic trait may affect autoimmune hepatitis and be amenable to therapeutic intervention.

MATERIALS AND METHODS

Pertinent abstracts were identified in PubMed by multiple search terms. The number of abstracts reviewed was 1689, and the number of full-length articles reviewed exceeded 150.

RESULTS

Activation of pro-inflammatory genes in autoimmune disease is associated with hypomethylation of deoxyribonucleic acid and modification of histones within chromatin. Organ-specific microribonucleic acids can silence genes by marking messenger ribonucleic acids for degradation, and they can promote inflammatory activity or immunosuppression. High circulating levels of the microribonucleic acids 21 and 122 have been demonstrated in autoimmune hepatitis, and they may increase production of pro-inflammatory cytokines. Microribonucleic acids are also essential for maintaining regulatory T cells. Drugs, pollutants, infections, diet and ageing can induce inheritable epigenetic changes favouring autoimmunity. Reversal is feasible by manipulating enzymes, transcription factors, gene-silencing molecules and toxic exposures or by administering methyl donors and correcting vitamin D deficiency. Gene targets, site specificity, efficacy and consequences are uncertain.

CONCLUSIONS

Potentially reversible epigenetic changes may affect the occurrence and outcome of autoimmune hepatitis, and investigations are warranted to determine the nature of these changes, key genomic targets, and feasible interventions and their consequences.

Role of HTLV-1 Tax and HBZ in the Pathogenesis of HAM/TSP

Human T cell lymphotropic virus type 1 (HTLV-1) infection can lead to development of adult T cell leukemia/lymphoma (ATL) or HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in a subset of infected subjects. Understanding the interaction between host and HTLV-1 and the molecular mechanisms associated with disease pathogenesis is critical for development efficient therapies. Two HTLV-1 genes, tax and HTLV-1 basic leucine zipper factor (HBZ), have been demonstrated to play important roles in HTLV-1 infectivity and the growth and survival of leukemic cells. Increased HTLV-1 Tax expression induces the expression of various cellular genes such as IL-2 and IL-15, which directly contributes to lymphocyte activation and immunopathogenesis in HAM/TSP patients. However, little is known about the molecular and cellular mechanism of HBZ in development of HAM/TSP. It has been reported that HBZ mRNA expression was detected in HAM/TSP patients higher than in asymptomatic carriers and correlated with proviral load and disease severity. Unlike HTLV-1 tax, HBZ escapes efficient anti-viral immune responses and therefore these reactivities are difficult to detect. Thus, it is important to focus on understanding the function and the role of HTLV-1 tax and HBZ in disease development of HAM/TSP and discuss the potential use of these HTLV-1 viral gene products as biomarkers and therapeutic targets for HAM/TSP.

Expanding Diversity and Common Goal of Regulatory T and B Cells. I: Origin, Phenotype, Mechanisms

Immunosuppressive activity of regulatory T and B cells is critical to limit autoimmunity, excessive inflammation, and pathological immune response to conventional antigens or allergens. Both types of regulatory cells are intensively investigated, however, their development and mechanisms of action are still not completely understood. Both T and B regulatory cells represent highly differentiated populations in terms of phenotypes and origin, however, they use similar mechanisms of action. The most investigated CD4+CD25+ regulatory T cells are characterized by the expression of Foxp3+ transcription factor, which is not sufficient to maintain their lineage stability and suppressive function. Currently, it is considered that specific epigenetic changes are critical for defining regulatory T cell stability in the context of their suppressive function. It is not yet known if similar epigenetic regulation determines development, lineage stability, and function of regulatory B cells. Phenotype diversity, confirmed or hypothetical developmental pathways, multiple mechanisms of action, and role of epigenetic changes in these processes are the subject of this review.

Differential profile of activated regulatory T cell subsets and microRNAs in tolerant liver transplant recipients

Regulatory T cells (Tregs) play a potential role in operational tolerance in liver transplantation (LT) patients, and microRNAs (miRNAs) are known to be involved in immunological responses and tolerance. Thus, we analyzed the implication of different peripheral blood Treg subsets and miRNAs on LT tolerance in 24 tolerant (Tol) and 23 non-tolerant (non-Tol) LT recipients by cellular, genetic, and epigenetic approximation. Non-Tol patients had a lower demethylation rate of the forkhead box P3 (FOXP3) regulatory T cell-specific demethylated region (TSDR) than Tol patients that correlated with the frequency of circulating Tregs. Tol patients presented a different signature of Treg subset markers compared with non-Tol patients with increased expression of HELIOS and FOXP3 and a higher proportion of latency-associated peptide (LAP)⁺ Tregs and CD45RA^- human leukocyte antigen D related (HLA-DR)⁺ activated effector-memory Tregs. The expression of miR95, miR24, miR31, miR146a, and miR155 was higher in Tol than in non-Tol patients and was positively correlated with activated Treg markers. In conclusion, these data suggest that activated effector-memory Tregs and a TSDR-demethylation state of Tregs may play a role in the complex system of regulation of LT tolerance. In addition, we describe a set of miRNAs differentially expressed in human LT Tol patients providing suggestive evidence that miRNAs are implied in the preservation of self-tolerance as mediated by Tregs. Liver Transplantation 23 933-945 2017 AASLD.

Regulatory T Cell and Forkhead Box Protein 3 as Modulators of Immune Homeostasis

The transcription factor forkhead box protein 3 (FOXP3) is an essential molecular marker of regulatory T cell (Treg) development in different microenvironments. Tregs are cells specialized in the suppression of inadequate immune responses and the maintenance of homeostatic tolerance. Studies have addressed and elucidated the role played by FOXP3 and Treg in countless autoimmune and infectious diseases as well as in more specific cases, such as cancer. Within this context, the present article reviews aspects of the immunoregulatory profile of FOXP3 and Treg in the management of immune homeostasis, including issues relating to pathology as well as immune tolerance.

Non-small-cell lung cancer-induced immunosuppression by increased human regulatory T cells via Foxp3 promoter demethylation

Patients with non-small-cell lung cancer (NSCLC) have immune defects that are poorly understood. Forkhead box protein P3 (Foxp3) is crucial for immunosuppression by CD4(+) regulatory T cells (Tregs). It is not well known how NSCLC induces Foxp3 expression and causes immunosuppression in tumor-bearing patients. Our study found a higher percentage of CD4(+) Tregs in the peripheral blood of NSCLC compared with healthy donors. NSCLC patients showed demethylation of eight CpG sites within the Foxp3 promoter with methylation ratios negatively correlated with CD4(+)CD25(+)Foxp3(+) T levels. Foxp3 expression in CD4(+) Tregs was directly regulated by Foxp3 promoter demethylation and was involved in immunosuppression by NSCLC. To verify the effect of tumor cells on the phenotype and function of CD4(+) Tregs, we established a coculture system using NSCLC cell line and healthy CD4(+) T cells and showed that SPC-A1 induced IL-10 and TGF-β1 secretion by affecting the function of CD4(+) Tregs. The activity of DNA methyltransferases from CD4(+) T was decreased during this process. Furthermore, eight CpG sites within the Foxp3 promoter also appeared to have undergone demethylation. Foxp3 is highly expressed in CD4(+) T cells, and this may be caused by gene promoter demethylation. These induced Tregs are highly immunosuppressive and dramatically inhibit the proliferative activity of naïve CD4(+) T cells. Our study provides one possible mechanism describing Foxp3 promoter demethylation changes by which NSCLC down-regulates immune responses and contributes to tumor progression. Foxp3 represents an important target for NSCLC anti-tumor immunotherapy.

Virus-Induced Demyelination: The Case for Virus(es) in Multiple Sclerosis

Multiple Sclerosis (MS) is the most common demyelinating disease of man with over 400,000 cases in the United States and over 2.5 million cases worldwide. There are over 64,000 citations in Pubmed dating back as far as 1887. Much has been learned over the past 129 years with a recent burst in therapeutic options (mostly anti-inflammatory) with newer medications in development that are neuroprotective and/or neuroreparative. However, with all these advancements the cause of MS remains elusive. There is a clear interplay of genetic, immunologic, and environmental factors that influences both the development and progression of this disorder. This chapter will give a brief overview of the history and pathogenesis of MS with attention to how host immune responses in genetically susceptible individuals contribute to the MS disease process. In addition, we will explore the role of infectious agents in MS as potential “triggers” of disease. Models of virus-induced demyelination will be discussed, with an emphasis on the recent interest in human herpesviruses and the role they may play in MS disease pathogenesis. Although we remain circumspect as to the role of any microbial pathogen in MS, we suggest that only through well-controlled serological, cellular immune, molecular, and animal studies we will be able to identify candidate agents. Ultimately, clinical interventional trials that either target a specific pathogen or class of pathogens will be required to make definitive links between the suspected agent and MS.

HTLV-1 subgroups associated with the risk of HAM/TSP are related to viral and host gene expression in peripheral blood mononuclear cells, independent of the transactivation functions of the viral factors

Among human T cell leukemia virus type 1 (HTLV-1)-infected individuals, the risk of developing HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) across lifetime differs between ethnic groups. There is an association between HTLV-1 tax gene subgroups (subgroup-A or subgroup-B) and the risk of HAM/TSP in the Japanese population. In this study, we investigated the full-length proviral genome sequences of various HTLV-1-infected cell lines and patient samples. The functional differences in the viral transcriptional regulators Tax and HTLV-1 bZIP factor (HBZ) between each subgroup and the relationships between subgroups and the clinical and laboratory characteristics of HAM/TSP patients were evaluated. The results of these analyses indicated the following: (1) distinct nucleotide substitutions corresponding to each subgroup were associated with nucleotide substitutions in viral structural, regulatory, and accessory genes; (2) the HBZ messenger RNA (mRNA) expression in HTLV-1-infected cells was significantly higher in HAM/TSP patients with subgroup-B than in those with subgroup-A; (3) a positive correlation was observed between the expression of HBZ mRNA and its target Foxp3 mRNA in HAM/TSP patients with subgroup-B, but not in patients with subgroup-A; (4) no clear differences were noted in clinical and laboratory characteristics between HAM/TSP patients with subgroup-A and subgroup-B; and (5) no functional differences were observed in Tax and HBZ between each subgroup based on reporter gene assays. Our results indicate that although different HTLV-1 subgroups are characterized by different patterns of viral and host gene expression in HAM/TSP patients via independent mechanisms of direct transcriptional regulation, these differences do not significantly affect the clinical and laboratory characteristics of HAM/TSP patients.

The Macrophage Galactose-Type C-Type Lectin (MGL) Modulates Regulatory T Cell Functions

Regulatory T cells (Tregs) are physiologically designed to prevent autoimmune disease and maintain self-tolerance. In tumour microenvironments, their presence is related to a poor prognosis, and they influence the therapeutic outcome due to their capacity to suppress the immune response by cell-cell contact and to release immunosuppressive cytokines. In this study, we demonstrate that Treg immunosuppressive activity can be modulated by the cross-linking between the CD45RA expressed by Tregs and the C-type lectin MGL. This specific interaction strongly decreases the immunosuppressive activity of Tregs, restoring the proliferative capacity of co-cultured T lymphocytes. This effect can be attributed to changes in CD45RA and TCR signalling through the inhibition of Lck and inactivation of Zap-70, an increase in the Foxp3 methylation status and, ultimately, the reduced production of suppressive cytokines. These results indicate a role of MGL as an immunomodulator within the tumour microenvironment interfering with Treg functions, suggesting its possible use in the design of anticancer vaccines.