Selective immunointervention in autoimmune diseases: lessons from multiple sclerosis

Tuberculosis and Autoimmunity

Tuberculosis remains a common and dangerous chronic bacterial infection worldwide. It is long-established that pathogenesis of many autoimmune diseases is mainly promoted by inadequate immune responses to bacterial agents, among them Mycobacterium tuberculosis. Tuberculosis is a multifaceted process having many different outcomes and complications. Autoimmunity is one of the processes characteristic of tuberculosis; the presence of autoantibodies was documented by a large amount of evidence. The role of autoantibodies in pathogenesis of tuberculosis is not quite clear and widely disputed. They are regarded as: (1) a result of imbalanced immune response being reactive in nature, (2) a critical part of TB pathogenicity, (3) a beginning of autoimmune disease, (4) a protective mechanism helping to eliminate microbes and infected cells, and (5) playing dual role, pathogenic and protective. There is no single autoimmunity-mechanism development in tuberculosis; different pathways may be suggested. It may be excessive cell death and insufficient clearance of dead cells, impaired autophagy, enhanced activation of macrophages and dendritic cells, environmental influences such as vitamin D insufficiency, and genetic polymorphism, both of Mycobacterium tuberculosis and host.

Vitamin D Levels in Patients with Behcet's Disease: A Systematic Review and Meta-Analysis

OBJECTIVE

Behcet's disease (BD) is a chronic multisystem inflammatory disease classified as Variable Vessel Vasculitis with unclear etiology. We designed this systematic review and meta-analysis to evaluate vitamin D status in Behcet's disease patients with this background.

METHODS

We performed this systematic review and meta-analysis according to (PRISMA) guidelines. We included all observational studies in humans published in English, evaluating the association of 25(OH)D concentrations in Behcet's patients. Two reviewers (HRK and AE) independently searched the databases and screened articles based on their titles and abstracts. A third reviewer resolved all disagreements. We performed analysis using Cochrane Program Review Manager Version 5.3. The protocol for this review was registered on PROSPERO (CRD42020197426).

RESULTS

A total of 341 publications were initially identified according to the search strategy. Finally, 12 publications were included in the meta-analysis. We performed this meta-analysis on 1265 participants from different studies with a sample size from 63 to 224 individuals. In studies comparing Active and Inactive subgroups of patients with Behcet's Disease, we found a significantly lower serum level of vitamin D in patients with Active BD (-0.4; 95%CI: -0.61, -0.25; p<0.00001). We found that the serum level of vitamin D in Behcet's Disease is significantly higher than Health Controls (0.5; 95%CI: 0.15, 0.50; p=0.00001).

CONCLUSION

We demonstrated that the existing evidence is consistent with the hypothesis that an increased serum level of vitamin D would be associated with substantially lower risk of active Behcet's disease.

Proteomics comparison of cerebrospinal fluid of relapsing remitting and primary progressive multiple sclerosis

Background

Based on clinical representation of disease symptoms multiple sclerosis (MScl) patients can be divided into two major subtypes; relapsing remitting (RR) MScl (85–90%) and primary progressive (PP) MScl (10–15%). Proteomics analysis of cerebrospinal fluid (CSF) has detected a number of proteins that were elevated in MScl patients. Here we specifically aimed to differentiate between the PP and RR subtypes of MScl by comparing CSF proteins.

Methodology/Principal Findings

CSF samples (n = 31) were handled according to the same protocol for quantitative mass spectrometry measurements we reported previously. In the comparison of PP MScl versus RR MScl we observed a number of differentially abundant proteins, such as protein jagged-1 and vitamin D-binding protein. Protein jagged-1 was over three times less abundant in PP MScl compared to RR MScl. Vitamin D-binding protein was only detected in the RR MScl samples. These two proteins were validated by independent techniques (western blot and ELISA) as differentially abundant in the comparison between both MScl types.

Conclusions/Significance

The main finding of this comparative study is the observation that the proteome profiles of CSF in PP and RR MScl patients overlap to a large extent. Still, a number of differences could be observed. Protein jagged-1 is a ligand for multiple Notch receptors and involved in the mediation of Notch signaling. It is suggested in literature that the Notch pathway is involved in the remyelination of MScl lesions. Aberration of normal homeostasis of Vitamin D, of which approximately 90% is bound to vitamin D-binding protein, has been widely implicated in MScl for some years now. Vitamin D directly and indirectly regulates the differentiation, activation of CD4+ T-lymphocytes and can prevent the development of autoimmune processes, and so it may be involved in neuroprotective elements in MScl.

Lymphocyte Subpopulations, Oxidative Burst and Apoptosis in Peripheral Blood Cells of Patients with Multiple Sclerosis–Effect of Interferon-β

At present, the most efficient therapeutical treatment of multiple sclerosis (MS) is achieved by IFN-beta. However, its in vivo effects remain incompletely understood. If applied parenterally, the hydrophobic IFN-beta acts primarily on blood cells with probable selectivity for functionally different lymphocyte subpopulations, monocytes and granulocytes. We have investigated the expression of the activation marker interleukin-2 receptor-alpha (CD25) on CD3+ T cells, CD19+ B cells, foetal-type gamma(delta)+CD3+ T cells and foetal-type CD5+CD19+ B cells of the peripheral blood. In addition, the oxidative burst activity and apoptosis have been determined in mononuclear and polymorphonuclear blood cells, respectively. The study accompanied a phase III trial with IFN-beta1b (BETAFERON, Schering). Two groups of MS patients with relapsing-remitting course of the disease have been investigated at 8 time points (days 0, 5, 15, 31, 60, 90, 180 and 270 after starting therapy): (1) verum group (n = 8) with application of 8 Mill. units IFN-beta1 b every other day, and (2) placebo group (n = 4) with application of placebo for 3 months and therapy as in (1) from day 90 onward. The main results were: (1) Activated T cells decreased until day 180 in the verum group and return thereafter to pre-treatment values, whereas in the placebo group the values remained relatively stable over the whole observation period. (2) Activated B cells increased between days 90 and 270 in both groups, i.e. after verum application in both groups. (3) Foetal-type B cells were more activated than total B and T cells with increase over time in both groups. (4) Foetal-type T cells exerted relatively stable intra-individual levels with generally low CD25 expression, but punctual CD25 peaks in both groups. (5) The spontaneous oxidative burst was higher in lymphocytes, more variable in monocytes and faster increasing in granulocytes in the verum group than in the placebo group. (6) Apoptosis of mononuclear cells and granulocytes showed similar variations in the verum and placebo groups with the exception of a selective increase over time of the proportion of granulocytes undergoing induced apoptosis in the verum group. It is concluded that IFN-beta has the following main effects on the immune system of MS patients: (1) the T cell immunity is systemically and reversibly suppressed, (2) the foetal-type lymphocytes, which are responsible for the first line of defence of infections, are stimulated in the long range, (3) the oxidative burst activity is increased in lymphocytes and granulocytes and instable in monocytes, and (4) the inducibility of apoptosis in granulocytes is increased. Re-examination of the altered blood cell parameters after long-term IFN-beta therapy is warranted.

Vitamin D deficiency in undifferentiated connective tissue disease

INTRODUCTION

Both experimental and clinical data provide evidence that vitamin D is one of those important environmental factors that can increase the prevalence of certain autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, insulin-dependent diabetes mellitus, and inflammatory bowel disease. The aim of the present study was to investigate the prevalence of vitamin D insufficiency in patients with undifferentiated connective tissue disease (UCTD).

METHODS

Plasma 25(OH)D3 levels in 161 UCTD patients were measured in both summer and winter periods. Autoantibody profiles (antinuclear antibody, anti-U1-ribonucleoprotein, anti-SSA, anti-SSB, anti-Jo1, anti-Scl70, anti-double-stranded DNA, anti-centromere, anti-cardiolipin, rheumatoid factor, and anti-cyclic citrullinated peptide) and clinical symptoms of the patients were assessed.

RESULTS

Plasma levels of 25(OH)D3 in UCTD patients were significantly lower compared with controls in both summer and winter periods (UCTD summer: 33 +/- 13.4 ng/mL versus control: 39.9 +/- 11.7 ng/mL, P = 0.01; UCTD winter: 27.8 +/- 12.48 ng/mL versus control: 37.8 +/- 12.3 ng/mL, P = 0.0001). The presence of dermatological symptoms (photosensitivity, erythema, and chronic discoid rash) and pleuritis was associated with low levels of vitamin D. During the average follow-up period of 2.3 years, 35 out of 161 patients (21.7%) with UCTD further developed into well-established connective tissue disease (CTD). Patients who progressed into CTDs had lower vitamin D levels than those who remained in the UCTD stage (vitamin D levels: CTD: 14.7 +/- 6.45 ng/mL versus UCTD: 33.0 +/- 13.4 ng/mL, P = 0.0001).

CONCLUSIONS

In patients with UCTD, a seasonal variance in levels of 25(OH)D3 was identified and showed that these levels were significantly lower than in controls during the corresponding seasons. Our results suggest that vitamin D deficiency in UCTD patients may play a role in the subsequent progression into well-defined CTDs.

Vitamin D receptor agonists in the treatment of autoimmune diseases: selective targeting of myeloid but not plasmacytoid dendritic cells

Vitamin D receptor (VDR) agonists are well known for their capacity to control calcium and bone metabolism and to regulate growth and differentiation of many cell types. More recently, it has become clear that VDR agonists possess immunoregulatory properties and, in particular, pronounced protolerogenic activities. These agents have been shown to be effective in several models of autoimmune diseases and are the most used topical agents in the treatment of psoriasis, a Th1 and Th17 cell-mediated autoimmune disease of the skin, indicating their potential applicability in the treatment of a variety of autoimmune diseases. VDR agonists can act directly on T cells, but dendritic cells (DCs) seem to be their primary targets. A potentially very important activity of VDR agonists is their capacity to induce in vitro and in vivo tolerogenic DCs able to enhance CD4(+)CD25(+) suppressor T cells that, in turn, inhibit effector T-cell responses. Novel data now show that VDR agonists selectively modulate tolerogenic properties in blood myeloid but not plasmacytoid DCs, shedding new light on the multifaceted immunoregulatory properties of these agents.

The coming of age of galectins as immunomodulatory agents: impact of these carbohydrate binding proteins in T cell physiology and chronic inflammatory disorders

Immune cell homoeostasis is attributed to multiple distinct safety valves that are interconnected and intervene at defined checkpoints of the life cycle of immunocytes to guarantee clonal expansion and functional inactivation of self-reactive potentially autoaggressive lymphocytes. Galectins, animal lectins defined by shared consensus amino acid sequence and affinity for beta-galactose containing oligosaccharides, are found on various cells of the immune system, and their expression is associated with the differentiation and activation status of these cells. Over the past few years, galectins have been implicated in the regulation of many aspects of T cell physiology such as cell activation, differentiation, and apoptosis. In addition, a growing body of experimental evidence indicates that galectins may play critical roles in the modulation of chronic inflammatory disorders, autoimmunity, and cancer. Given the increased interest of immunologists in this field, the growing body of information raised during the past few years and the potential use of galectins as novel anti-inflammatory agents or targets for immunosuppressive drugs, we will summarise recent advances on the role of galectins in different aspects of T cell physiology and their impact in the development and/or resolution of chronic inflammatory disorders, autoimmunity, and cancer.

Multiple Sclerosis and Hashimoto Thyroiditis

Multiple sclerosis (MS) occurs with immune-mediated mechanisms, but its pathogenesis is not accurately known. The coexistence of MS with other autoimmune diseases has been reported. The hypothesis that MS coexists with other autoimmune diseases has been supported by the reported association of MS with type I diabetes mellitus and inflammatory disorders. Even though there have been only rare reports of associations between Hashimoto thyroiditis and MS, this association is important for its clinical and therapeutic aspects. Proximal muscle weakness, myalgia, and fatigue are symptoms that are common in both MS and hypothyroidism. When MS patients demonstrate these symptoms, thyroid function tests should be performed. The thyroid hormone levels of MS patients being treated with interferon-beta and Campath-1H also should be monitored. The authors report the clinical data of 2 definite MS patients who also fulfilled criteria for Hashimoto thyroiditis.

Antigen-based immunointervention in human autoimmune diseases

Antigen administration can ameliorate autoimmune disease via various mechanisms, including deletion of autoreactive cells, induction of regulatory T cells, and deviation to non-pathogenic or protective responses. All these mechanisms of immunointervention have been successfully used to prevent and sometimes treat experimental models of autoimmune diseases. Based on these results, expectations have been raised for exploiting similar strategies to inhibit pathogenic autoreactive T cells in human autoimmune diseases. Among them, mucosal administration of autoantigen is an attractive mode of immunointervention still awaiting demonstration of clinical efficacy in human autoimmune diseases. A further step in this direction is now provided by the clear-cut immune deviation observed following oral administration of a disease-related peptide to rheumatoid arthritis patients, leading to inhibition of Th1 while enhancing Th2 and possibly Foxp3-positive regulatory T cells.

Intervention in autoimmunity: The potential of vitamin D receptor agonists

Vitamin D receptor (VDR) agonists are well known for their capacity to control calcium metabolism and to regulate growth and differentiation of many cell types. More recently, it has become clear that VDR agonists possess immunoregulatory properties and, in particular, pronounced pro-tolerogenic activities. VDR agonists can act directly on T cells, but DCs appear to be their primary targets. The capacity of VDR agonists to modulate DC and T cell functions is mediated by VDR expression in both cell types and by the presence of common targets in their signal transduction pathways, such as the nuclear factor NF-kappaB that is downregulated by VDR agonists in APCs and in T cells. A potentially very important activity of VDR agonists is their capacity to induce in vitro and in vivo tolerogenic DCs able to enhance CD4+CD25+ suppressor T cells that, in turn, inhibit Th1 cell responses. These mechanisms of action can explain some of the immunoregulatory properties of VDR agonists in the treatment of Th1-mediated autoimmune diseases, but may also represent a physiologic element in the VDR-mediated regulation of innate and adaptive immune responses.

MHC-bound antigens and proteomics for novel target discovery

The MHC molecules present normal as well as disease-related and pathogen-derived peptides to T cells as a way of alerting the immune system of the health status of a cell. Proteomic technologies involving immunoaffinity purification are now extensively used to separate MHC complexes from their peptide cargo, and then the petides are sequenced by tandem mass spectrometry. The identified peptides are tested as vaccine candidates for viral diseases, immunostimulants for treating cancer, and immune-tolerance-inducing agents for autoimmune disorders. One of the challenges in devising novel HLA-peptide-based immunotherapies is to decipher whether a therapeutic window exists between the induction of tumor immunity and the onset of autoimmunity, which can have dangerous sequelae. This review will cover these topics with an overview of the vast possibilities emerging in the field of proteomic analyses of MHC-bound antigens as novel targets for immunotherapy.

Immunotherapeutic approaches in multiple sclerosis

The progress in understanding the mechanisms of T cell activation, inactivation and modulation has been translated into different immunotherapeutic strategies aiming at treating multiple sclerosis (MS). Key attack points for selective immunointervention in MS include modulation of antigen recognition, costimulation blockade, induction of regulatory cells, deviation to non-pathogenic or protective responses, neutralization of proinflammatory cytokines and administration of anti-inflammatory cytokines. In addition, several attempts have been made using less specific forms of immunointervention. The two resounding successes in the immunotherapy of MS, IFN-failed and glatiramer acetate, contrast with the many attempts, equally based on sound reasoning and promising animal data. Nevertheless, antigen-based immunointervention will continue to be tested clinically, and we will certainly witness the application of more articulate strategies able to selectively target cytokine production by Th1 or Th2 cells or to modify the Th1/Th2 balance. Perhaps, an effective manipulation of pathogenic and protective cells in MS may eventually rely on a combination of antigen- and cytokine-based approaches to selectively target autoreactive T cells and divert them from autoaggression. Most importantly, new avenues are opening, such as the use of chemokine receptor antagonists, and others look very promising, as targeting dendritic cells to favour their capacity to induce regulatory T cells.

Immunomodulatory effects of vitamin D receptor ligands in autoimmune diseases

The active form of vitamin D, 1,25-Dihydroxyvitamin D3 [l,25(OH)2D3], is a secosteroid hormone that binds to the vitamin D receptor (VDR), a member of the superfamily of nuclear receptors for steroid hormones, thyroid hormone, and retinoic acid. VDR ligands regulate calcium and bone metabolism, control cell proliferation and differentiation, and exert immunoregulatory activities. The immunoregulatory properties of VDR ligands are currently exploited clinically for the topical treatment of psoriasis, a Th1 cell-mediated autoimmune disease of the skin, but recent advances in understanding their functions and novel insights into the immunomodulatory mechanisms they control suggest a wider applicability in the treatment of autoimmune diseases. In addition to direct effects on T cell activation, VDR ligands modulate with different mechanisms the phenotype and function of antigen-presenting cells (APCs), and, in particular, of dendritic cells (DCs). In vitro and in vivo experiments have shown that VDR ligands induce DCs to acquire tolerogenic properties that favor the induction of regulatory rather than effector T cells. These intriguing actions of VDR ligands have been demonstrated in several experimental models and could be exploited, in principle, to treat a variety of human autoimmune diseases.