B cell characterization and reactivity analysis in multiple sclerosis

Ocrevus reduces TH40 cells, a biomarker of systemic inflammation, in relapsing multiple sclerosis (RMS) and in progressive multiple sclerosis (PMS)

Treating MS has been difficult. One successful drug is Ocrelizumab (anti-CD20), used for the chronic relapsing MS (RMS) and the progressive MS (PMS) forms. TH40 cells are pathogenic effector T cells that increase in percentage and numbers during chronic inflammation. Here we show that in the earliest MS course, clinically isolated syndrome (CIS), TH40 cells expand in number. In PMS TH40 cell numbers remain expanded demonstrating sustained chronic inflammation. In RMS TH40 cells were found in CSF and express CD20. Ocrelizumab reduced TH40 cells to healthy control levels in patients. During treatment inflammatory cytokine producing TH40 cells were decreased.

The Diversity of Encephalitogenic CD4+ T Cells in Multiple Sclerosis and Its Animal Models

Autoreactive CD4+ T cells, which target antigens in central nervous system (CNS) myelin, are widely believed to play a critical role in the pathogenesis of multiple sclerosis (MS) in concert with other immune effectors. This theory is supported by data from animal model experiments, genome-wide association studies, and immune profiles of individuals with MS. Furthermore, disease modifying agents that target lymphocytes significantly reduce the rate of MS clinical exacerbations. However, the properties of myelin-reactive CD4+ T cells that are critical for their pathogenic activities are not understood completely. This article reviews the literature on encephalitogenic CD4+ T cells, with an emphasis on T-helper (Th) lineage and cytokine production. An increased understanding of the spectrum of encephalitogenic T cells and how they differ from protective subsets is necessary for the development of the next generation of more effective and safer immunomodulatory therapies customized for individuals with MS and related disorders.

Changes in the Multiple Sclerosis Treatment Paradigm. What Do We Do Now and What Were We Doing Before?

BACKGROUND AND PURPOSE

The number of disease-modifying drugs (DMDs) available for treating relapsing-remitting multiple sclerosis is increasing. Numerous drugs have been approved since 2010 in South America, which has increased the complexity of the treatment algorithm. The aim of this study was to determine the changes in multiple sclerosis treatments relative to the underlying causes and the availability of new DMDs in Argentina.

METHODS

A descriptive retrospective study was carried out on a group of 59 patients diagnosed with RRMS who use more than one DMD.

RESULTS

The first treatment switch occurred before 2010 in 27% of the patients and after 2010 in the other 73%. Efficacy was the main reason for switching during both periods. A second treatment switch was required in 25% of the patients, with this occurring after 2010 in 86.6% of them. Interferon was the most-used drug before 2010 and fingolimod was the most-used drug thereafter.

CONCLUSIONS

We have identified that the tendency for treatment changes has increased following the arrival of new drugs. Efficacy has been the main cause of these changes.

Optical coherence tomography as a biomarker of neurodegeneration in multiple sclerosis: A review

Neurodegeneration is one the most important pathological factors which contributes to permanent disability in multiple sclerosis (MS). Optical coherence tomography (OCT) measurements of macular ganglion cell layer (mGCL) and retinal nerve fiber layer (RNFL) have been proposed as biomarkers of axonal damage in MS. The aim of this review is to describe the most relevant findings regarding OCT and axonal damage in MS. We have selected studies that describe retina impairment in MS patients, and those which quantitatively assess the relationship between OCT and physical disability, cognitive impairment and relationship between OCT and magnetic resonance imaging (MRI). Results show that there is a relationship between the degree of retinal layers reduction and physical or cognitive disability and degenerative changes in MRI.

Therapeutic strategies in multiple sclerosis: a focus on neuroprotection and repair and relevance to schizophrenia

Multiple sclerosis is the leading nontraumatic cause of neurologic disability in young adults. The need to prevent neurodegeneration and promote repair in multiple sclerosis (MS) has gained increasing interest in the last decade leading to the search and development of pharmacological agents and non-pharmacologic strategies able to target not only the inflammatory but also the neurodegenerative component of the disease. This paper will provide an overview of the therapeutics currently employed in MS, with a focus on their potential neuroprotective effects and on the MRI methods employed to detect and monitor in-vivo neuroprotection and repair and the relevance of this information to schizophrenia investigation and treatment.

New Directions in Multiple Sclerosis Therapy: Matching Therapy with Pathogenesis

All currently approved therapies for multiple sclerosis (MS) modulate systemic immune components prior to their entry into the central nervous system (CNS). Available data indicate they lack impact on the progressive phases of disease; the more potent systemic immune-directed agents predispose to development of infectious or neoplastic disorders. Development of new agents that enhance disease stage related efficacy and limit systemic toxicity will need to consider the underlying mechanisms related to each phase of the clinical disorder, namely relapses, remission, and progression. This report focuses on disease related mechanisms ongoing within the CNS that contribute to the different phases of MS and how these may serve as potential therapeutic targets. Such mechanisms include CNS compartment specific immunologic properties especially as related to the innate immune system and neural cell-related properties that are determinants of the extent of actual tissue injury and repair (or lack thereof).

Compositional changes of B and T cell subtypes during fingolimod treatment in multiple sclerosis patients: a 12-month follow-up study

Background and objective

The long term effects of fingolimod, an oral treatment for relapsing-remitting (RR) multiple sclerosis (MS), on blood circulating B and T cell subtypes in MS patients are not completely understood. This study describes for the first time the longitudinal effects of fingolimod treatment on B and T cell subtypes. Furthermore, expression of surface molecules involved in antigen presentation and costimulation during fingolimod treatment are assessed in MS patients in a 12 month follow-up study.

Methods

Using flow cytometry, B and T cell subtypes, and their expression of antigen presentation, costimulation and migration markers were measured during a 12 month follow-up in the peripheral blood of MS patients. Data of fingolimod-treated MS patients (n = 49) were compared to those from treatment-naive (n = 47) and interferon-treated (n = 27) MS patients.

Results

In the B cell population, we observed a decrease in the proportion of non class-switched and class-switched memory B cells (p<0.001), both implicated in MS pathogenesis, while the proportion of naive B cells was increased during fingolimod treatment in the peripheral blood (PB) of MS patients (p<0.05). The remaining T cell population, in contrast, showed elevated proportions of memory conventional and regulatory T cells (p<0.01) and declined proportions of naive conventional and regulatory cells (p<0.05). These naive T cell subtypes are main drivers of MS pathogenesis. B cell expression of CD80 and CD86 and programmed death (PD) -1 expression on circulating follicular helper T cells was increased during fingolimod follow-up (p<0.05) pointing to a potentially compensatory mechanism of the remaining circulating lymphocyte subtypes that could provide additional help during normal immune responses.

Conclusions

MS patients treated with fingolimod showed a change in PB lymphocyte subtype proportions and expression of functional molecules on T and B cells, suggesting an association with the therapeutic efficacy of fingolimod.

Immunomodulation neuroprotection and remyelination - the fundamental therapeutic effects of glatiramer acetate: a critical review

Multiple sclerosis (MS) is a multifaceted heterogeneous disease with various patterns of tissue damage. In addition to inflammation and demyelination, widespread axonal and neuronal pathologies are central components of this disease. MS therapies aim to restrain the pathological processes, enhance protective mechanisms, and prevent disease progression. The amino acid copolymer, glatiramer acetate (GA, Copaxone), an approved treatment for MS, has a unique mode of action. Evidence from the animal model experimental autoimmune encephalomyelitis (EAE) and from MS patients indicates that GA affects various levels of the innate and the adaptive immune response, inducing deviation from the pro-inflammatory to the anti-inflammatory pathways. This includes competition for the binding of antigen presenting cells, driving dendritic cells, monocytes, and B-cells towards anti-inflammatory responses, induction of Th2/3 and T-regulatory cells, and downregulating of both Th1 and Th-17 cells. The immune cells induced by GA reach the inflamed disease organ and secrete in situ anti-inflammatory cytokines alleviating the pathological processes. Furthermore, cumulative findings have revealed that in addition to its immunomodulatory activities GA promotes neuroprotective repair processes such as neurotrophic factors secretion and remyelination. This review aims to provide a comprehensive overview on the diverse mechanism of action of GA in EAE/MS, in particular on the in situ effect of GA and its ability to generate neuroprotection and repair in the CNS. In view of its immunomodulatory activity, the beneficial effects of GA in various models of additional autoimmune related pathologies, such as immune rejection and inflammatory bowel disease (IBD), are also presented.

Autoantibody profiling in multiple sclerosis using arrays of human protein fragments

Profiling the autoantibody repertoire with large antigen collections is emerging as a powerful tool for the identification of biomarkers for autoimmune diseases. Here, a systematic and undirected approach was taken to screen for profiles of IgG in human plasma from 90 individuals with multiple sclerosis related diagnoses. Reactivity pattern of 11,520 protein fragments (representing ∼38% of all human protein encoding genes) were generated on planar protein microarrays built within the Human Protein Atlas. For more than 2,000 antigens IgG reactivity was observed, among which 64% were found only in single individuals. We used reactivity distributions among multiple sclerosis subgroups to select 384 antigens, which were then re-evaluated on planar microarrays, corroborated with suspension bead arrays in a larger cohort (n = 376) and confirmed for specificity in inhibition assays. Among the heterogeneous pattern within and across multiple sclerosis subtypes, differences in recognition frequencies were found for 51 antigens, which were enriched for proteins of transcriptional regulation. In conclusion, using protein fragments and complementary high-throughput protein array platforms facilitated an alternative route to discovery and verification of potentially disease-associated autoimmunity signatures, that are now proposed as additional antigens for large-scale validation studies across multiple sclerosis biobanks.

Rheumatoid arthritis synovial tissue harbours dominant B-cell and plasma-cell clones associated with autoreactivity

OBJECTIVE

To identify potential autoreactive B-cell and plasma-cell clones by quantitatively analysing the complete human B-cell receptor (BCR) repertoire in synovium and peripheral blood in early and established rheumatoid arthritis (RA).

METHODS

The BCR repertoire was screened in synovium and blood of six patients with early RA (ERA) (<6 months) and six with established RA (ESRA) (>20 months). In two patients, the repertoires in different joints were compared. Repertoires were analysed by next-generation sequencing from mRNA, generating >10 000 BCR heavy-chain sequence reads per sample. For each clone, the degree of expansion was calculated as the percentage of the total number of reads encoding the specific clonal sequence. Clones with a frequency ≥ 0.5% were considered dominant.

RESULTS

Multiple dominant clones were found in inflamed synovium but hardly any in blood. Within an individual patient, the same dominant clones were detected in different joints. The majority of the synovial clones were class-switched; however, the fraction of clones that expressed IgM was higher in ESRA than ERA patients. Dominant synovial clones showed autoreactive features: in ERA in particular the clones were enriched for immunoglobulin heavy chain gene segment V4-34 (IGHV4-34) and showed longer CDR3 lengths. Dominant synovial clones that did not encode IGHV4-34 also had longer CDR3s than peripheral blood.

CONCLUSIONS

In RA, the synovium forms a niche where expanded--potentially autoreactive--B cells and plasma cells reside. The inflamed target tissue, especially in the earliest phase of disease, seems to be the most promising compartment for studying autoreactive cells.

The mechanism of action of glatiramer acetate in multiple sclerosis and beyond

In multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE), the immune system reacts again self myelin constitutes in the central nervous system (CNS), initiating a detrimental inflammatory cascade that leads to demyelination as well as axonal and neuronal pathology. The amino acid copolymer glatiramer acetate (GA, Copaxone) is an approved first-line treatment for MS that has a unique mode of action. Accumulated evidence from EAE-induced animals and from MS patients indicates that GA affects various levels of the innate and the adaptive immune response, generating deviation from the pro-inflammatory to the anti-inflammatory pathway. This review aims to provide a comprehensive perspective on the diverse mechanism of action of GA in EAE/MS, in particular on the in situ immunomodulatory effect of GA and its ability to generate neuroprotective repair consequences in the CNS. In view of its immunomodulatory activity, the beneficial effect of GA in various models of other autoimmune related pathologies, such as immune rejection and inflammatory bowel disease (IBD) is noteworthy.

Identifying autoantigens in demyelinating diseases: valuable clues to diagnosis and treatment?

PURPOSE OF REVIEW

Identification of autoantigens in demyelinating diseases is essential for the understanding of the pathogenesis. Immune responses against these antigens could be used as biomarkers for diagnosis, prognosis and treatment responses. Knowledge of antigen-specific immune responses in individual patients is also a prerequisite for antigen-based therapies.

RECENT FINDINGS

A proportion of patients with demyelinating disease have antibodies to aquaporin 4 (AQP4) or myelin oligodendrocyte glycoprotein (MOG). Patients with anti-AQP4 have the distinct clinical presentation of neuromyelitis optica (NMO), and these patients often also harbour other autoimmune responses. In contrast, anti-MOG is seen in patients with different disease entities such as childhood multiple sclerosis (MS), acute demyelinating encephalomyelitis (ADEM), anti-AQP4 negative NMO, and optic neuritis, but hardly in adult MS. A number of new candidate autoantigens have been identified and await validation. Antigen-based therapies are mainly aimed at tolerizing T-cell responses against myelin basic protein (MBP) and have shown only modest or no clinical benefit so far.

SUMMARY

Currently, only few patients with demyelinating diseases can be characterized based on their autoantibody profile. The most prominent antigens in this respect are MOG and AQP4. Further research has to focus on the validation of newly discovered antigens as biomarkers.

Laquinimod modulates B cells and their regulatory effects on T cells in multiple sclerosis

Laquinimod is an orally administered drug under development for the treatment of Multiple Sclerosis (MS), lacking a fully elucidated mode of action. We assessed the immunomodulatory effects of laquinimod in vitro on human B cells from healthy or MS patients, cultured alone or with CD4(+) T cells. Laquinimod modulated B cell markers, mainly by increasing the regulatory ones CD25, IL10 and CD86, and decreased IL4, while increasing IL10 and TGFβ in both B and T cells, in a B cell-mediated manner. These findings shed additional light on the mechanisms underlying the effects of laquinimod in MS and potentially other immune-mediated diseases.

Altered microRNA expression in B lymphocytes in multiple sclerosis: towards a better understanding of treatment effects

MicroRNAs (miRNAs) are posttranscriptional regulators of gene expression. We compared the expression of 1059 miRNAs in B lymphocytes from untreated and natalizumab treated relapsing-remitting multiple sclerosis (RRMS) patients and healthy volunteers (HV). Forty nine miRNAs were down-regulated in untreated MS patients compared with HV. A distinct pattern of 10 differentially expressed miRNAs was found in natalizumab treated patients compared with untreated patients. Two clusters, i.e. miR-106b-25 and miR-17-92, were particularly deregulated. MiRNA-mRNA interaction analysis revealed B cell receptor, phosphatidyl-inositol-3-kinase (PI3K) and phosphatase and tensin homology (PTEN) signaling being the key affected pathways. We discovered deregulated viral miRNAs in untreated patients as compared with HV and natalizumab treated patients, a novel finding that may be related to latency and activation of viruses in MS. Our findings provide first insights into miRNA dependent regulation of B cell function in MS and the impact of a therapy not primarily targeting B cells on this regulation.

Antinuclear and antiphospholipid antibodies in patients with multiple sclerosis

The prevalence of autoantibodies in multiple sclerosis (MS) patients and their clinical associations differ between various studies. This study investigated antiphospholipid and antinuclear antibodies in 85 patients with multiple sclerosis (MS) and clinically isolated syndrome (CIS) with regard to their association with demographic features, MS specific clinical features and symptoms of connective tissue diseases. Autoantibodies tested included antinuclear antibodies (ANA) with their specificities and anticardiolipin (aCL) and anti-beta-2-glycoprotein I (anti-β2GPI) antibodies. Antinuclear antibodies were more prevalent in MS patients than in controls (63.5% vs. 3.3%; p < 0.01) and in 19% of patients specific antinuclear antibodies were detected. Anti-β2GPI IgM antibodies were more frequent in MS patients than in the control group (20% vs. 3.3%; p < 0.05). The frequency of anticardiolipin antibodies did not differ between MS patients and controls. MS patients seropositive for ANA and extractable nuclear antigens (ENA) had significantly shorter disease duration than seronegative patients (p < 0.05) and a lower disability score (Expanded Disability Status Score; EDSS) (p < 0.05). Anti-β2GPI antibodies were more frequent in patients with secondary progressive MS (SP-MS) and specific ANA antibodies were more frequent in patients with clinically isolated syndrome (CIS) (p < 0.05). The presence of autoantibodies was not associated with the predominant site of neurological involvement or the clinical features of connective tissue diseases.

More to come: humoral immune responses in MS

Interest in the role of B-cells in multiple sclerosis (MS) pathogenesis has increased, and a number of B-cell targeted therapies are currently in clinical trials. B-cells are key mediators of the humoral immune response, with roles including antibody production and acting as antigen presenting cells. Whilst previously, the presence of B-cells within MS plaques has been thought to be secondary to T-cell dysregulation, it is now becoming clear that B-cells play an independent role in disease. In this review we will discuss the potential role of B-cells in MS, how this influences our understanding of the disease, and potential therapeutic implications.

Pearls in autoimmunity

This manuscript does a review of the more frequent issues published at Autoimmunity Reviews, Journal of Autoimmunity and Autoimmunity in the period of January–December 2009. The following topics were commented: (1) multiple sclerosis (MS) and its relationships with Epstein Barr infection, with vitamin D polymorphism and the new modalities of MS treatment. (2) Type 1 diabetes and genetic discovers, studies with GAD 65 and IA-2 autoantigen and the association T1D and autoimmune organ-specific diseases. (3) Autoimmune thyroid disorders and its association with susceptibility genes and polymorphisms. (4) Multiplex autoantibody profiling approaches in MS and rheumatoid arthritis. (5) Th17 cytokine in primary biliary cirrhosis, experimental autoimmune encephalomyelitis and celiac disease. (6) Vitamin D and experimental autoimmune prostatitis and pulmonary alveolar proteinosis.

Peptide reactivity between multiple sclerosis (MS) CSF IgG and recombinant antibodies generated from clonally expanded plasma cells in MS CSF

We employed 19 recombinant antibodies (rAbs) generated from clonally expanded plasma cells, and native IgG from cerebrospinal fluid (CSF) of three multiple sclerosis (MS) patients for panning with phage displayed random peptide libraries. Specific peptide epitopes/mimotopes were identified and characterized. Importantly, peptide-antibody interactions were shared by rAbs and native IgG from the same patient. Three peptides strongly interacted with at least one other MS CSF, but not to inflammatory CNS controls. Database searches revealed several protein candidates including stress proteins, cell surface proteins, and neuronal proteins. Peptides derived from the candidate proteins were recognized by rAbs. Identification of peptide epitopes/mimotopes in MS may provide clues regarding disease-relevant antigens.

A case for regulatory B cells in controlling the severity of autoimmune-mediated inflammation in experimental autoimmune encephalomyelitis and multiple sclerosis

Multiple sclerosis (MS) is considered to be a T cell-mediated autoimmune disease that results in the presence of inflammatory lesions/plaques associated with mononuclear cell infiltrates, demyelination and axonal damage within the central nervous system (CNS). To date, FDA approved therapies in MS are thought to largely function by modulation of the immune response. Since autoimmune responses require many arms of the immune system, the direct cellular mechanisms of action of MS therapeutics are not definitively known. The mouse model of MS, experimental autoimmune encephalomyelitis (EAE), has been instrumental in deciphering the mechanism of action of MS drugs. In addition, EAE has been widely used to study the contribution of individual components of the immune system in CNS autoimmunity. In this regard, the role of B cells in EAE has been studied in mice deficient in B cells due to genetic ablation and following depletion with a B cell-targeted monoclonal antibody (mAb) (anti-CD20). Both strategies have indicated that B cells regulate the extent of EAE clinical disease and in their absence disease is exacerbated. Thus a new population of "regulatory B cells" has emerged. One reoccurring component of regulatory B cell function is the production of IL-10, a pleiotropic cytokine with potent anti-inflammatory properties. B cell depletion has also indicated that B cells, in particular antibody production, play a pathogenic role in EAE. B cell depletion in MS using a mAb to CD20 (rituximab) has shown promising results. In this review, we will discuss the current thinking on the role of B cells in MS drawing from knowledge gained in EAE studies and clinical trials using therapeutics that target B cells.

The auto-antigen repertoire in myasthenia gravis

Myasthenia Gravis (MG) is an antibody-mediated autoimmune disorder affecting the postsynaptic membrane of the neuromuscular junction (NMJ). MG is characterized by an impaired signal transmission between the motor neuron and the skeletal muscle cell, caused by auto-antibodies directed against NMJ proteins. The auto-antibodies target the nicotinic acetylcholine receptor (nAChR) in about 90% of MG patients. In approximately 5% of MG patients, the muscle specific kinase (MuSK) is the auto-antigen. In the remaining 5% of MG patients, however, antibodies against the nAChR or MuSK are not detectable (idiopathic MG, iMG). Although only the anti-nAChR and anti-MuSK auto-antibodies have been demonstrated to be pathogenic, several other antibodies recognizing self-antigens can also be found in MG patients. Various auto-antibodies associated with thymic abnormalities have been reported, as well as many non-MG-specific auto-antibodies. However, their contribution to the cause, pathology and severity of the disease is still poorly understood. Here, we comprehensively review the reported auto-antibodies in MG patients and discuss their role in the pathology of this autoimmune disease.

A novel method for making human monoclonal antibodies

We have developed a B cell immortalization method for low B cell numbers per well using simultaneous B cell stimulation by CpG2006 and B cell infection by Epstein-Barr virus (EBV), followed by an additional CpG2006 and interleukin-2 (IL-2) stimulus. Using this method, immunoglobulin G (IgG)-producing immortalized B cell lines were generated from peripheral blood IgG⁺CD22⁺ B cells with an efficiency of up to 83%. Antibody can already be obtained from the culture supernatant after 3–4 weeks. Moreover, clonality analysis demonstrated monoclonality in 87% of the resulting immortalized B cell lines. Given the high immortalization efficiency and monoclonality rate, evidence is provided that no further subcloning is necessary. An important application of this B cell immortalization method is the characterization of (autoreactive) antibodies from patients with autoimmune disease. This could eventually lead to the identification of new autoantigens, disease markers or targets for therapy.

CD20-depleting therapy in autoimmune diseases: from basic research to the clinic

The B lymphocyte-associated antigen CD20 is becoming an important immunotherapy target for autoimmune diseases, although its biological function has not been defined. Besides rheumatoid arthritis, growing experience with B cell-depleting therapy indicates that it may be effective in Sjögren's syndrome, dermatomyositis-polymyositis, systemic lupus erythematosus and some types of vasculitides. However, controlled clinical trials are still lacking for some of these indications. Infection has not been seen as a major limitation to this therapy, but reports of progressive multifocal leukoencephalopathy in an extremely small number of patients are of concern. Here, we review the therapeutic actions of anti-CD20 antibodies, and the recent and ongoing clinical trials with CD20-depleting therapy in autoimmune diseases.

B cells and monocytes from patients with active multiple sclerosis exhibit increased surface expression of both HERV-H Env and HERV-W Env, accompanied by increased seroreactivity

Background

The etiology of the neurogenerative disease multiple sclerosis (MS) is unknown. The leading hypotheses suggest that MS is the result of exposure of genetically susceptible individuals to certain environmental factor(s). Herpesviruses and human endogenous retroviruses (HERVs) represent potentially important factors in MS development. Herpesviruses can activate HERVs, and HERVs are activated in MS patients.

Results

Using flow cytometry, we have analyzed HERV-H Env and HERV-W Env epitope expression on the surface of PBMCs from MS patients with active and stable disease, and from control individuals. We have also analyzed serum antibody levels to the expressed HERV-H and HERV-W Env epitopes. We found a significantly higher expression of HERV-H and HERV-W Env epitopes on B cells and monocytes from patients with active MS compared with patients with stable MS or control individuals. Furthermore, patients with active disease had relatively higher numbers of B cells in the PBMC population, and higher antibody reactivities towards HERV-H Env and HERV-W Env epitopes. The higher antibody reactivities in sera from patients with active MS correlate with the higher levels of HERV-H Env and HERV-W Env expression on B cells and monocytes. We did not find such correlations for stable MS patients or for controls.

Conclusion

These findings indicate that both HERV-H Env and HERV-W Env are expressed in higher quantities on the surface of B cells and monocytes in patients with active MS, and that the expression of these proteins may be associated with exacerbation of the disease.

Understanding autoimmune disease: new targets for drug discovery

A more complete understanding of the mechanisms that drive autoimmune diseases has begun to be translated into therapeutic options with significant clinical consequences. A clear example of this is the introduction of biological therapies, which have provided new therapeutic avenues, as well as validated the mediators (TNFalpha, IL-6), mechanisms (T cell costimulation, leukocyte migration), and cellular players (T and B lymphocytes) of the disease process itself. New discoveries into the role of Th17 and regulatory T cells and the epigenetic regulation of cytokine expression may offer novel intervention strategies to satisfy the unmet medical needs that still exist in these diseases.