New lessons about old molecules: how type I interferons shape Th1/Th17-mediated autoimmunity in the CNS

Targeted DeSUMOylation as a therapeutic strategy for multiple sclerosis

SUMO (small ubiquitin like modifier) conjugated proteins have emerged as an important post translational modifier of cellular function. SUMOylation modulates several cellular processes involved in transcriptional regulation of genes, protein-protein interactions and DNA damage and repair. Since abnormalities in SUMOylation has been observed in neoplastic and neurodegenerative disorders, the SUMO pathway has become an attractive site for targeting of new therapies to regulate SUMOylation and reduce disease burden. Conjugation of SUMO to their respective substrates is orchestrated by an enzymatic cascade involving three main enzymes, E1, activation enzyme, E2, conjugating enzyme and E3, a protein ligase. Each of these enzymes are therefore potential "druggable" sites for future therapeutics. SUMOylation is a well-known mechanism by which the innate immune response is regulated in response to viral infections and in the adaptive immune response to tumor immunity. We have shown that small molecules which inhibit the SUMO activation pathway are also capable of inhibiting autoimmune response. TAK981 which forms adducts with SUMO and anacardic acid which inhibits the E1 enzyme of the SUMO pathway were effective in preventing the development of experimental allergic encephalitis (EAE), a mouse model of multiple sclerosis. Anacardic acid and TAK981 inhibited activation of TH17 cells and reduced clinical and pathological injury in IL-17 mediated myelin oligodendrocyte glycoprotein (MOG) induced EAE. Ginkgolic acid, another known inhibitor of SUMO pathway, was also shown to be effective in reducing the severity of inflammatory arthropathies which is also IL-17 mediated. In addition, the increase in the transcription of myelin genes with TAK981 and anacardic acid improved remyelination in experimental models of demyelination. In the present review paper, we examine the mechanism of action of inhibitors of the SUMO pathway on regulating the immune response and the possibility of the use of these agents as therapeutics for MS.

Repurposing the cardiac glycoside digoxin to stimulate myelin regeneration in chemically-induced and immune-mediated mouse models of multiple sclerosis

Multiple sclerosis (MS) is a central nervous system (CNS) autoimmune disease characterized by inflammation, demyelination, and neurodegeneration. The ideal MS therapy would both specifically inhibit the underlying autoimmune response and promote repair/regeneration of myelin as well as maintenance of axonal integrity. Currently approved MS therapies consist of non-specific immunosuppressive molecules/antibodies which block activation or CNS homing of autoreactive T cells, but there are no approved therapies for stimulation of remyelination nor maintenance of axonal integrity. In an effort to repurpose an FDA-approved medication for myelin repair, we chose to examine the effectiveness of digoxin, a cardiac glycoside (Na+ /K+ ATPase inhibitor), originally identified as pro-myelinating in an in vitro screen. We found that digoxin regulated multiple genes in oligodendrocyte progenitor cells (OPCs) essential for oligodendrocyte (OL) differentiation in vitro, promoted OL differentiation both in vitro and in vivo in female naïve C57BL/6J (B6) mice, and stimulated recovery of myelinated axons in B6 mice following demyelination in the corpus callosum induced by cuprizone and spinal cord demyelination induced by lysophosphatidylcholine (LPC), respectively. More relevant to treatment of MS, we show that digoxin treatment of mice with established MOG35-55 -induced Th1/Th17-mediated chronic EAE combined with tolerance induced by the i.v. infusion of biodegradable poly(lactide-co-glycolide) nanoparticles coupled with MOG35-55 (PLG-MOG35-55 ) completely ameliorated clinical disease symptoms and stimulated recovery of OL lineage cell numbers. These findings provide critical pre-clinical evidence supporting future clinical trials of myelin-specific tolerance with myelin repair/regeneration drugs, such as digoxin, in MS patients.

Pre-clinical and Clinical Implications of "Inside-Out" vs. "Outside-In" Paradigms in Multiple Sclerosis Etiopathogenesis

Multiple Sclerosis (MS) is an immune-mediated neurological disorder, characterized by central nervous system (CNS) inflammation, oligodendrocyte loss, demyelination, and axonal degeneration. Although autoimmunity, inflammatory demyelination and neurodegeneration underlie MS, the initiating event has yet to be clarified. Effective disease modifying therapies need to both regulate the immune system and promote restoration of neuronal function, including remyelination. The challenge in developing an effective long-lived therapy for MS requires that three disease-associated targets be addressed: (1) self-tolerance must be re-established to specifically inhibit the underlying myelin-directed autoimmune pathogenic mechanisms; (2) neurons must be protected from inflammatory injury and degeneration; (3) myelin repair must be engendered by stimulating oligodendrocyte progenitors to remyelinate CNS neuronal axons. The combined use of chronic and relapsing remitting experimental autoimmune encephalomyelitis (C-EAE, R-EAE) (“outside-in”) as well as progressive diphtheria toxin A chain (DTA) and cuprizone autoimmune encephalitis (CAE) (“inside-out”) mouse models allow for the investigation and specific targeting of all three of these MS-associated disease parameters. The “outside-in” EAE models initiated by myelin-specific autoreactive CD4⁺ T cells allow for the evaluation of both myelin-specific tolerance in the absence or presence of neuroprotective and/or remyelinating agents. The “inside-out” mouse models of secondary inflammatory demyelination are triggered by toxin-induced oligodendrocyte loss or subtle myelin damage, which allows evaluation of novel therapeutics that could promote remyelination and neuroprotection in the CNS. Overall, utilizing these complementary pre-clinical MS models will open new avenues for developing therapeutic interventions, tackling MS from the “outside-in” and/or “inside-out”.

The role of TH17 cells in multiple sclerosis: Therapeutic implications

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) where immunopathology is thought to be mediated by myelin-reactive CD4⁺ T helper (TH) cells. The TH cells most commonly implicated in the pathogenesis of the disease are of TH1 and TH17 lineage, which are defined by the production of interferon-γ and interleukin-17, respectively. Moreover, there is emerging evidence for the involvement of TH17.1 cells, which share the hallmarks of TH1 and TH17 subsets. In this review, we summarise current knowledge about the potential role of TH17 subsets in the initiation and progression of the disease and put a focus on their response to approved immunomodulatory MS drugs. In this regard, TH17 cells are abundant in peripheral blood, cerebrospinal fluid and brain lesions of MS patients, and their counts and inflammatory mediators are further increased during relapses. Fingolimod and alemtuzumab induce a paramount decrease in central memory T cells, which harbour the majority of peripheral TH17 cells, while the efficacy of natalizumab, dimethyl fumarate and importantly hematopoietic stem cell therapy correlates with TH17.1 cell inhibition. Interestingly, also CD20 antibodies target highly inflammatory TH cells and hamper TH17 differentiation by IL-6 reductions. Moreover, recovery rates of TH cells best correlate with long-term efficacy after therapeutical immunodepletion. We conclude that central memory TH17.1 cells play a pivotal role in MS pathogenesis and they represent a major target of MS therapeutics.

Type I Interferon Supports Inducible Nitric Oxide Synthase in Murine Hepatoma Cells and Hepatocytes and during Experimental Acetaminophen-Induced Liver Damage

Cytokine regulation of high-output nitric oxide (NO) derived from inducible NO synthase (iNOS) is critically involved in inflammation biology and host defense. Herein, we set out to characterize the role of type I interferon (IFN) as potential regulator of hepatic iNOS in vitro and in vivo. In this regard, we identified in murine Hepa1-6 hepatoma cells a potent synergism between pro-inflammatory interleukin-β/tumor necrosis factor-α and immunoregulatory IFNβ as detected by analysis of iNOS expression and nitrite release. Upregulation of iNOS by IFNβ coincided with enhanced binding of signal transducer and activator of transcription-1 to a regulatory region at the murine iNOS promoter known to support target gene expression in response to this signaling pathway. Synergistic iNOS induction under the influence of IFNβ was confirmed in alternate murine Hepa56.1D hepatoma cells and primary hepatocytes. To assess iNOS regulation by type I IFN in vivo, murine acetaminophen (APAP)-induced sterile liver inflammation was investigated. In this model of acute liver injury, excessive necroinflammation drives iNOS expression in diverse liver cell types, among others hepatocytes. Herein, we demonstrate impaired iNOS expression in type I IFN receptor-deficient mice which associated with diminished APAP-induced liver damage. Data presented indicate a vital role of type I IFN within the inflamed liver for fine-tuning pathological processes such as overt iNOS expression.

Type I interferon pathway in CNS homeostasis and neurological disorders

Type I interferons (IFNs), IFN-α and IFN-β, represent the major effector cytokines of the host immune response against viruses and other intracellular pathogens. These cytokines are produced via activation of numerous pattern recognition receptors, including the Toll-like receptor signaling network, retinoic acid-inducible gene-1 (RIG-1), melanoma differentiation-associated protein-5 (MDA-5) and interferon gamma-inducible protein-16 (IFI-16). Whilst the contribution of type I IFNs to peripheral immunity is well documented, they can also be produced by almost every cell in the central nervous system (CNS). Furthermore, IFNs can reach the CNS from the periphery to modulate the function of not only microglia and astrocytes, but also neurons and oligodendrocytes, with major consequences for cognition and behavior. Given the pleiotropic nature of type I IFNs, it is critical to determine their exact cellular impact. Inappropriate upregulation of type I IFN signaling and interferon-stimulated gene expression have been linked to several CNS diseases termed "interferonopathies" including Aicardi-Goutieres syndrome and ubiquitin specific peptidase 18 (USP18)-deficiency. In contrast, in the CNS of mice with virus-induced neuroinflammation, type I IFNs can limit production of other cytokines to prevent potential damage associated with chronic cytokine expression. This capacity of type I IFNs could also explain the therapeutic benefits of exogenous type I IFN in chronic CNS autoimmune diseases such as multiple sclerosis. In this review we will highlight the importance of a well-balanced level of type I IFNs for healthy brain physiology, and to what extent dysregulation of this cytokine system can result in brain 'interferonopathies'.

Interferon-beta affects mitochondrial activity in CD4+ lymphocytes: Implications for mechanism of action in multiple sclerosis

Background:

Whereas cellular immune function depends on energy supply and mitochondrial function, little is known on the impact of immunotherapies on cellular energy metabolism.

Objective:

The objective of this paper is to assess the effects of interferon-beta (IFN-β) on mitochondrial function of CD4+ T cells.

Methods:

Intracellular adenosine triphosphate (iATP) in phytohemagglutinin (PHA)-stimulated CD4+ cells of multiple sclerosis (MS) patients treated with IFN-β and controls were analyzed in a luciferase-based assay. Mitochondrial-transmembrane potential (ΔΨm) in IFN-β-treated peripheral blood mononuclear cells (PBMCs) was investigated by flow cytometry. Expression of genes involved in mitochondrial oxidative phosphorylation (OXPHOS) in CD4+ cells of IFN-β-treated individuals and correlations between genetic variants in the key metabolism regulator PGC-1α and IFN-β response in MS were analyzed.

Results:

IFN-β-treated MS patients exhibited a dose-dependent reduction of iATP levels in CD4+ T cells compared to controls ( p < 0.001). Mitochondrial effects were reflected by depolarization of ΔΨm. Expression data revealed changes in the transcription of OXPHOS-genes. iATP levels in IFN-β-responders were reduced compared to non-responders ( p < 0.05), and the major T allele of the SNP rs7665116 of PGC-1α correlated with iATP-levels.

Conclusion:

Reduced iATP-synthesis ex vivo and differential expression of OXPHOS-genes in CD4+ T cells point to unknown IFN-β effects on mitochondrial energy metabolism, adding to potential pleiotropic mechanisms of action.

Role of microglia in CNS autoimmunity

Multiple sclerosis (MS) is the most common autoimmune disease of the central nervous system (CNS) in the Western world. The disease is characterized histologically by the infiltration of encephalitogenic T_H1/T_H17-polarized CD4⁺ T cells, B cells, and a plethora of myeloid cells, resulting in severe demyelination ultimately leading to a degeneration of neuronal structures. These pathological processes are substantially modulated by microglia, the resident immune competent cells of the CNS. In this overview, we summarize the current knowledge regarding the highly diverse and complex function of microglia during CNS autoimmunity in either promoting tissue injury or tissue repair. Hence, understanding microglia involvement in MS offers new exciting paths for therapeutic intervention.

Neuromyelitis optica-like pathology is dependent on type I interferon response

Neuromyelitis optica is an antibody-mediated autoimmune inflammatory disease of the central nervous system. Reports have suggested that interferon beta which is beneficial for multiple sclerosis, exacerbates neuromyelitis optica. Our aim was to determine whether type I interferon plays a role in the formation of neuromyelitis optica lesions. Immunoglobulin G from a neuromyelitis optica patient was injected intracerebrally with human complement to type I interferon receptor deficient and wildtype mice. Loss of aquaporin-4 and glial fibrillary acidic protein was reduced in type I interferon receptor deficient mice brain. Our findings suggest that type I interferon signaling contributes to neuromyelitis optica pathogenesis.

Pro-Inflammatory Signaling by IL-10 and IL-22: Bad Habit Stirred Up by Interferons?

Interleukin (IL)-10 and IL-22 are key members of the IL-10 cytokine family that share characteristic properties such as defined structural features, usage of IL-10R2 as one receptor chain, and activation of signal transducer and activator of transcription (STAT)-3 as dominant signaling mode. IL-10, formerly known as cytokine synthesis inhibitory factor, is key to deactivation of monocytes/macrophages and dendritic cells. Accordingly, pre-clinical studies document its anti-inflammatory capacity. However, the outcome of clinical trials assessing the therapeutic potential of IL-10 in prototypic inflammatory disorders has been disappointing. In contrast to IL-10, IL-22 acts primarily on non-leukocytic cells, in particular epithelial cells of intestine, skin, liver, and lung. STAT3-driven proliferation, anti-apoptosis, and anti-microbial tissue protection is regarded a principal function of IL-22 at host/environment interfaces. In this hypothesis article, hidden/underappreciated pro-inflammatory characteristics of IL-10 and IL-22 are outlined and related to cellular priming by type I interferon. It is tempting to speculate that an inherent inflammatory potential of IL-10 and IL-22 confines their usage in tissue protective therapy and beyond that determines in some patients efficacy of type I interferon treatment.

IFNα converts IL-22 into a cytokine efficiently activating STAT1 and its downstream targets

Besides their antiviral activity, type I Interferons (IFN) display context-specific immunomodulation. In contrast to long-known IFNα/β, Interleukin (IL)-22 is an anti-bacterial, largely tissue protective cytokine that recently gained attention. Herein, cellular IFNα/IL-22 interactions are investigated. We report that pre-conditioning of epithelial cells with IFNα initiated dramatic changes in IL-22 signaling normally dominated by signal transducer and activator of transcription (STAT)-3. Specifically, by using human DLD1 colon epithelial/carcinoma cells we demonstrate that, upon IFNα, IL-22 converts into a cytokine robustly activating STAT1 and its downstream pro-inflammatory targets CXCL9, CXCL10, and inducible nitric oxide synthase (iNOS). Accordingly, only after IFNα pre-incubation was IL-22-induced STAT1 binding to the CXCL10 promoter detectable. Using the viral mimic polyinosinic:polycytidylic acid and the IFNα/β antagonist B18R we furthermore demonstrate the capability of endogenous IFN to promote IL-22-induced STAT1 activation and expression of CXCL10. IL-22-induced STAT1 activation subsequent to IFNα priming became likewise apparent in human Caco2 colon epithelial/carcinoma cells, HepG2 hepatoma cells, and primary keratinocytes. Current observations may relate to characteristics of IFNα/β in clinical therapy and expose margins of tissue protection by IL-22 application.

Lithium controls central nervous system autoimmunity through modulation of IFN-γ signaling

Inhibitors of glycogen synthase kinase 3 (GSK3) are being explored as therapy for chronic inflammatory diseases. We previously demonstrated that the GSK inhibitor lithium is beneficial in experimental autoimmune encephalomyelitis (EAE), the mouse model of multiple sclerosis. In this study we report that lithium suppresses EAE induced by encephalitogenic interferon-γ (IFN-γ)-producing T helper (Th1) cells but not by interleukin (IL)-17-producing T helper (Th17) cells. The therapeutic activity of lithium required functional IFN-γ-signaling, but not the receptor for type I IFN (IFNAR). Inhibitor/s of GSK3 attenuated IFN-γ dependent activation of the transcription factor STAT1 in naïve T cells as well as in encephalitogenic T cells and Th1 cells. The inhibition of STAT1 activation was associated with reduced IFN-γ production and decreased expansion of encephalitogenic Th1 cells. Furthermore, lithium treatment induced Il27 expression within the spinal cords of mice with EAE. In contrast, such treatment of Ifngr(-/-) mice did not induce Il27 and was associated with lack of therapeutic response. Our study reveals a novel mechanism for the efficacy of GSK3 targeting in EAE, through the IFN-γ-STAT1 axis that is independent IFNAR-STAT1 axis. Overall our findings set the framework for the use of GSK3 inhibitors as therapeutic agents in autoimmune neuroinflammation.

Janus-like effects of type I interferon in autoimmune diseases

In multiple sclerosis, type I interferon (IFN) is considered immune-modulatory, and recombinant forms of IFN-β are the most prescribed treatment for this disease. This is in contrast to most other autoimmune disorders, because type I IFN contributes to the pathologies. Even within the relapsing-remitting multiple sclerosis (RRMS) population, 30-50% of MS patients are non-responsive to this treatment, and it consistently worsens neuromyelitis optica, a disease similar to RRMS. In this article, we discuss the recent advances in the field of autoimmunity and introduce the theory explain how type I IFNs can be pro-inflammatory in disease that is predominantly driven by a Th17 response and are therapeutic when disease is predominantly Th1.

Differential requirements for IRF-2 in generation of CD1d-independent T cells bearing NK cell receptors

NK cell receptors (NKRs) such as NK1.1, NKG2D, and Ly49s are expressed on subsets of CD1d-independent memory phenotype CD8(+) and CD4(-)CD8(-) T cells. However, the mechanism for the generation and functions of these NKR(+) T cells remained elusive. In this study, we found that CD1d-independent Ly49(+) T cells were reduced severely in the spleen, bone marrow, and liver, but not thymus, in mice doubly deficient for IFN regulatory factor-2 (IRF-2) and CD1d, in which the overall memory phenotype T cell population was contrastingly enlarged. Because a large fraction of Ly49(+) T cells coexpressed NK1.1 or NKG2D, the reduction of Ly49(+) T cells resulted indirectly in underrepresentation of NK1.1(+) or NKG2D(+) cells. Ly49(+) T cell deficiency was observed in IRF-2(-/-) mice additionally lacking IFN-α/βR α-chain (IFNAR1) as severely as in IRF-2(-/-) mice, arguing against the involvement of the accelerated IFN-α/β signals due to IRF-2 deficiency. Rather, mice lacking IFN-α/βR alone also exhibited relatively milder Ly49(+) T cell reduction, and IL-2 could expand Ly49(+) T cells from IFNAR1(-/-), but not from IRF-2(-/-), spleen cells in vitro. These results together indicated that IRF-2 acted in Ly49(+) T cell development in a manner distinct from that of IFN-α/β signals. The influence of IRF-2 deficiency on Ly49(+) memory phenotype T cells observed in this study suggested a unique transcriptional program for this T cell population among other NKR(+) T and memory phenotype T cells.

Type I interferons as ambiguous modulators of chronic inflammation in the central nervous system

Type I interferons (IFNs) were originally identified as antiviral effector molecules that exert pleiotropic physiological processes ranging from immune modulation, control of proliferation, apoptosis to antitumor activity. However, type I IFNs were recently also shown to apply both beneficial and detrimental effects to the central nervous system (CNS) and a tightly balanced equilibrium between cellular activation and inhibition seems to be essential to maintain homeostasis within the CNS. In inflammatory pathologies affecting the CNS, type I IFNs are in the center of attention not only because interferon beta (IFN-β) is used as a standard therapeutic in the treatment of relapsing–remitting multiple sclerosis (MS), but also as type I IFN expression is associated with distinct pathologies. Despite the great efficiency of IFN-β in reducing MS relapses and attenuation of novel inflammatory lesions is well documented, underlying molecular mechanisms and cellular target specificities are just beginning to emerge. In contrast to the curative effects, aberrant activation of the type I IFN response were also recently shown to be associated with detrimental effects exemplified by the Aicardi–Goutières syndrome (AGS), a severe disabling autoimmune inflammatory encephalopathy. This review will highlight the dual role of type I interferons during chronic CNS inflammation. Recently uncovered molecular and cellular mechanisms in the etiology of AGS and experimental autoimmune encephalomyelitis (EAE), the murine model of MS will be highlighted.

Protective effect of an elastase inhibitor in a neuromyelitis optica-like disease driven by a peptide of myelin oligodendroglial glycoprotein

BACKGROUND

The pathology of neuromyelitis optica (NMO), in contrast to multiple sclerosis, comprises granulocyte infiltrates along extensive lengths of spinal cord, as well as optic nerve. Furthermore, IFN-β treatment worsens NMO. We recently found that experimental autoimmune encephalomyelitis (EAE) induced with Th17 cells is exacerbated by IFN-β, in contrast to disease induced with Th1 where treatment attenuated symptoms.

OBJECTIVE

This study demonstrates the similarities between NMO and Th17 EAE and how neutrophils mediate pathology in Th17 disease.

METHODS

Levels of blood biomarkers in NMO were assessed by Luminex and ELISA. Effects of IFN-β on neutrophils were assessed by culture assays and immunofluorescence. EAE was induced by transfer of myelin-specific Th1 or Th17 cells and treated with Sivelestat sodium hydrate, a neutrophil elastase inhibitor.

RESULTS

We show Th17 cytokines, granulocyte chemokines, type 1 interferon and neutrophil elastase are elevated in patients with definitive NMO. In culture, we find that IFN-β stimulates neutrophils to release neutrophil elastase. In Th17 EAE, we demonstrate neutrophilic infiltration in the optic nerve and spinal cord which was not present in Th1 EAE. Blockade of neutrophil elastase with Sivelestat had efficacy in Th17 EAE but not Th1 EAE.

CONCLUSIONS

The similarities between Th17 EAE and NMO indicate that this model represents several aspects of NMO. Neutrophils are critical in the pathologies of both Th17-EAE and NMO, and therefore blockade of neutrophil elastase is a promising target in treating NMO.

Type I IFN promotes IL-10 production from T cells to suppress Th17 cells and Th17-associated autoimmune inflammation

Whereas the immune system is essential for host defense against pathogen infection or endogenous danger signals, dysregulated innate and adaptive immune cells may facilitate harmful inflammatory or autoimmune responses. In the CNS, chronic inflammation plays an important role in the pathogenesis of neurodegenerative diseases such as multiple sclerosis (MS). Our previous study has demonstrated a critical role for the type I IFN induction and signaling pathways in constraining Th17-mediated experimental autoimmune encephalomyelitis (EAE), an animal model of human MS. However, it remains unknown if self-reactive Th17 cells can be reprogrammed to have less encephalitogenic activities or even have regulatory effects through modulation of innate pathways. In this study, we investigated the direct effects of type I IFN on Th17 cells. Our data show that IFNβ treatment of T cells cultured under Th17 polarizing conditions resulted in reduced production of IL-17, but increased production of IL-10. We also found that IFNβ induced IL-10 production by antigen specific T cells derived from immunized mice. Furthermore, IFNβ treatment could suppress the encephalitogenic activity of myelin-specific T cells, and ameliorate clinical symptoms of EAE in an adoptive transfer model. Together, results from this study suggest that IFNβ may induce antigen-specific T cells to produce IL-10, which in turn negatively regulate Th17-mediate inflammatory and autoimmune response.

Cytosolic RIG-I-like helicases act as negative regulators of sterile inflammation in the CNS

The action of cytosolic RIG-I-like helicases (RLHs) in the CNS during autoimmunity is largely unknown. Using a mouse model of multiple sclerosis, we found that mice lacking the RLH adaptor IPS-1 developed exacerbated disease that was accompanied by markedly higher inflammation, increased axonal damage and elevated demyelination with increased encephalitogenic immune responses. Furthermore, activation of RLH ligands such as 5'-triphosphate RNA oligonucleotides decreased CNS inflammation and improved clinical signs of disease. RLH stimulation repressed the maintenance and expansion of committed T(H)1 and T(H)17 cells, whereas T-cell differentiation was not altered. Notably, T(H)1 and T(H)17 suppression required type I interferon receptor engagement on dendritic cells, but not on macrophages or microglia. These results identify RLHs as negative regulators of T(H)1 and T(H)17 responses in the CNS, demonstrate a protective role of the RLH pathway for brain inflammation, and establish oligonucleotide ligands of RLHs as potential therapeutics for the treatment of multiple sclerosis.

Cytokines and the regulation of fungus-specific CD4 T cell differentiation

CD4 T cells play important and non-redundant roles in protection against infection with diverse fungi. Distinct CD4 T cell subsets can mediate protection against fungal disease where Th1 and Th17 CD4 T cell subsets have been found to promote fungal clearance and protective immunity against diverse fungal pathogens. The differentiation of naïve CD4 T cells into Th1 or Th17 cells is crucially controlled by their interaction with dendritic cells and instructed by cytokines. IL-12 and IFN-γ promote Th1 differentiation while TGF-β, IL-6, IL-1, IL-21 and IL-23 promote Th17 differentiation and maintenance. The production of these cytokines by DCs is in turn regulated by innate receptors triggered in response to fungal infection. In this review we will discuss the contributions of cytokines found to influence fungus-specific CD4 T cell differentiation and their role in defense against fungal disease. We will also highlight the contributions of innate receptors involved in recognition of fungi and how they shape cytokine secretion and CD4 T cell differentiation.

A randomized clinical trial of autologous T-cell therapy in multiple sclerosis: subset analysis and implications for trial design

Background: Tovaxin is an autologous T-cell immunotherapy under investigation for the treatment of MS. The product consists of in vitro expanded myelin-reactive T-cells manufactured against up to six immunodominant peptides derived from three myelin antigens.

Methods: A Phase 2b placebo controlled study (TERMS) was conducted in 150 subjects to gather safety and efficacy data in relapsing-remitting MS and clinically isolated syndrome subjects.

Results: Tovaxin had a favorable safety profile. Although no statistically significant clinical or radiological benefit of Tovaxin immunotherapy was identified in the modified intent-to-treat population, a prospective analysis of subjects with more active disease favored Tovaxin in terms of annualized relapse rate (ARR) and disability progression. An analysis also found a possible legacy effect of prior disease-modifying treatment (DMT) which may have contributed to a lowered ARR in the placebo group. DMT-naïve subjects treated with Tovaxin had a lower ARR compared to the placebo group, particularly in those with active baseline disease (ARR≥1, ARR>1). However, clinical benefit was not was accompanied by a treatment-dependent improvement in MRI measures.

Conclusions: Previous DMT exposure may reduce effect size and study power. Limiting subject selection to DMT-treatment-naïve individuals may be a reasonable approach to phase 2 or proof-of-concept studies of limited duration.

Overlapping, additive and counterregulatory effects of type II and I interferons on myeloid dendritic cell functions

Dendritic cells (DCs) are central player in immunity by bridging the innate and adaptive arms of the immune system (IS). Interferons (IFNs) are one of the most important factors that regulate both innate and adaptive immunity too. Thus, the understanding of how type II and I IFNs modulate the immune-regulatory properties of DCs is a central issue in immunology. In this paper, we will address this point in the light of the most recent literature, also highlighting the controversial data reported in the field. According to the wide literature available, type II as well as type I IFNs appear, at the same time, to collaborate, to induce additive effects or overlapping functions, as well as to counterregulate each one's effects on DC biology and, in general, the immune response. The knowledge of these effects has important therapeutic implications in the treatment of infectious/autoimmune diseases and cancer and indicates strategies for using IFNs as vaccine adjuvants and in DC-based immune therapeutic approaches.

Transcriptional activators of human genes with programmable DNA-specificity

TAL (transcription activator-like) effectors are translocated by Xanthomonas bacteria into plant cells where they activate transcription of target genes. DNA target sequence recognition occurs in a unique mode involving a central domain of tandem repeats. Each repeat recognizes a single base pair in a contiguous DNA sequence and a pair of adjacent hypervariable amino acid residues per repeat specifies which base is bound. Rearranging the repeats allows the design of novel TAL proteins with predictable DNA-recognition specificities. TAL protein-based transcriptional activation in plant cells is mediated by a C-terminal activation domain (AD). Here, we created synthetic TAL proteins with designed repeat compositions using a novel modular cloning strategy termed “Golden TAL Technology”. Newly programmed TAL proteins were not only functional in plant cells, but also in human cells and activated targeted expression of exogenous as well as endogenous genes. Transcriptional activation in different human cell lines was markedly improved by replacing the TAL-AD with the VP16-AD of herpes simplex virus. The creation of TAL proteins with potentially any desired DNA-recognition specificity allows their versatile use in biotechnology.

Interferon-β exacerbates Th17-mediated inflammatory disease

Interferon (IFN)-β is the treatment most often prescribed for relapsing-remitting multiple sclerosis (RRMS). 30-50% of MS patients, however, do not respond to IFN-β. In some cases, IFN-β exacerbates MS, and it consistently worsens neuromyelitis optica (NMO). To eliminate unnecessary treatment for patients who are non-responsive to IFN-β, and to avoid possible harm, researchers are identifying biomarkers that predict treatment outcome before treatment is initiated. These biomarkers reveal insights into the mechanisms of disease. Recent discoveries on human samples from patients with RRMS, NMO, psoriasis, rheumatoid arthritis, systemic lupus erythematosus and ulcerative colitis, indicate that IFN-β is ineffective and might worsen clinical status in diverse diseases when a Th17 immune response is prominent.