High-Dose Dexamethasone Inhibits BAFF Expression in Patients with Immune Thrombocytopenia

Translating mechanisms into therapeutic strategies for immune thrombocytopenia (ITP): Lessons from clinical trials

Immune thrombocytopenia (ITP) is an autoimmune disorder that causes a significant reduction in peripheral blood platelet count. Fortunately, due to an increased understanding of ITP, there have been significant improvements in the diagnosis and treatment of these patients. Over the past decade, there have been a variety of proven therapeutic options available for ITP patients, including intravenous immunoglobulins (IVIG), Rituximab, corticosteroids, and thrombopoietin receptor agonists (TPO-RAs). Although the effectiveness of current therapies in treating more than two-thirds of patients, still some patients do not respond well to conventional therapies or fail to achieve long-term remission. Recently, a significant advancement has been made in identifying various mechanisms involved in the pathogenesis of ITP, leading to the development of novel treatments targeting these pathways. It seems that new agents that target plasma cells, Bruton tyrosine kinase, FcRn, platelet desialylation, splenic tyrosine kinase, and classical complement pathways are opening new ways to treat ITP. In this study, we reviewed the pathophysiology of ITP and summarized updates in this population's management and treatment options. We also took a closer look at the 315 ongoing trials to investigate their progress status and compare the effectiveness of interventions. May our comprehensive view of ongoing clinical trials serve as a guiding beacon, illuminating the path towards future trials of different drugs in the treatment of ITP patients.

Expression of B-cell activating factor in pediatric patients with immune thrombocytopenia: a single institutional series and review of literature

B-cell-activating factor (BAFF) is a crucial cytokine supporting survival and differentiation of B cells. Dysregulation of BAFF is involved in the pathogenesis of B-cell related autoimmune diseases including immune thrombocytopenia (ITP). The aim of this study was to evaluate the significance of BAFF expression in pediatric ITP patients. Eighty pediatric patients with ITP are subdivided in three groups. Group I included (32 patients) diagnosed with acute ITP less than 3 months, group II (48 patients) diagnosed with persistent ITP (from 3 to 12 months) and chronic ITP (more than 12 months) and group III 20 healthy controls. Complete blood picture, autoimmune profile, antiplatelet antibodies, coagulation profile, bone marrow examination, and RT-PCR were performed to detect the expression for BAF for all participants in this study. BAFF expression levels significantly increased in cases rather than in controls. BAFF Expression Value significantly increased in groups I & II (3.10 ± 1.99&3.29 ± 2.58) compared to controls (0.83 ± 0.45) as p < .001 for both. On the other hand, groups I & II were comparable in BAFF Expression Value (p = .470). BAFF expression increased in ITP patients, implying a function in the disease's pathogenesis.

B cell-activating factor is involved in thrombocytopenia in patients with liver cirrhosis

Liver cirrhosis (LC) involves B cells that produce anti-glycoprotein (GP) IIb/IIIa antibodies, found in primary immune thrombocytopenia (ITP). The role of autoimmunity in the pathology of thrombocytopenia in LC was investigated using 25 LC patients with thrombocytopenia, 18 ITP patients, and 30 healthy controls. Anti-GPIIb/IIIa antibody-producing B cells were quantified using enzyme-linked immunospot assay. Platelet-associated and plasma anti-GPIIb/IIIa antibody, plasma B cell-activating factor (BAFF), and a proliferation-inducing ligand (APRIL) levels were measured using enzyme-linked immunosorbent assay. B cell subset fractions and regulatory T cells (Tregs) were quantified using flow cytometry.The number of anti-GPIIb/IIIa antibody-producing B cells was significantly higher in LC patients than in ITP patients and healthy controls (both p < 0.001). Platelet-associated anti-GPIIb/IIIa antibodies were significantly higher in LC patients than in ITP patients and healthy controls (p = 0.002, p < 0.001, respectively). BAFF levels were significantly higher in LC patients than in ITP patients and healthy controls (p = 0.001 and p < 0.001, respectively), and APRIL levels were significantly higher in LC patients than in healthy controls (p < 0.001). Anti-GPIIb/IIIa antibody-producing B cells and platelet-associated anti-GPIIb/IIIa antibodies were positively correlated with BAFF levels in LC patients. LC patients had more naïve B cells and plasmablasts than healthy controls (p = 0.005, p = 0.03, respectively); plasmablasts were positively correlated with BAFF levels. LC patients had similar Tregs levels as ITP patients and healthy controls. Therefore, excessive BAFF production in LC patients with thrombocytopenia is likely associated with autoimmune B cell response, inducing anti-GPIIb/IIIa antibody production.

Increasing numbers of CD19 + CD24highCD38high regulatory B cells and pre-germinal center B cells reflect activated autoimmunity and predict future treatment response in patients with untreated immune thrombocytopenia

The pathophysiology of immune thrombocytopenia (ITP) is poorly understood, particularly aspects regarding abnormal homeostasis and dysregulation of B cells. In this study, we analyzed peripheral lymphocyte subsets in patients with untreated ITP and healthy controls, and examined correlations between cell percentages/counts and titers of serum cytokines and antibodies. We also compared ITP patients who later required second-line therapies and those who did not. The percentages of CD19 + CD24^highCD38^high regulatory B cells, pre-germinal center (GC) B cells, and plasmablast-like B cells were significantly higher in ITP patients than in healthy controls. Absolute counts of regulatory B cells and pre-GC B cells were significantly higher in those who needed second-line therapies. In addition, serum B cell-activating factor belonging to the tumor necrosis factor family (BAFF) levels and platelet-associated immune globulin G antibody titers correlated positively with regulatory B cell, pre-GC B cell, and auto-reactive B cell counts. Serum interferon-α (IFN-α) levels were elevated in four ITP patients with high auto-reactive B cell counts. These results indicate that increases in regulatory B cells and pre-GC B cells may reflect activated autoimmunity induced by BAFF and/or IFN-α. Consequently, evaluation of B cell subsets in untreated ITP patients may predict treatment response.

Increased ADAM10 expression in patients with immune thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disease, which is characterized by abnormal of T immunity. A disintegrin and metalloproteinase (ADAM) 10, a member of proteinase family, has been demonstrated to regulate T cell proliferation and effector function. Considering the closely association of dysregulation of T cell function with ITP, whether ADAM10 involves in the pathogenesis of ITP remains unclear. In this study, 54 active ITP patients, 18 ITP in remission and 24 age and gender matched healthy control were enrolled. Peripheral blood mononuclear cells (PBMCs) were isolated from patients and control for isolation of RNA and plasma which were used to measure mRNA level of ADAM10 and tissue inhibitor of metalloproteinase 3 (TIMP3) by quantitative real-time PCR and soluble level of FasL and lymphocyte activation gene-3 (LAG-3) in plasma by ELISA. Meanwhile, T cell activation was measured by flow cytometry. Our results showed significantly higher expression of ADAM10 and lower expression of TIMP3 in active ITP patients compared with control, which were all restored into normal level in remission patients. Consistent with the expression profile of ADAM10, increased soluble plasma level of FasL and LAG-3 were observed in active ITP patients and reduced to normal level in patients in remission. Furthermore, increased T cell activation as demonstrated by higher expression of HLA-DR and CD69 were found in active ITP patients. In conclusion, elevated expression of ADAM10 was associated with the pathogenesis and development of ITP and therapeutically targeting it might be a novel approach for the treatment of ITP.

Pathogenesis-oriented approaches for the management of corticosteroid-resistant or relapsedprimary immune thrombocytopenia

Primary immune thrombocytopenia (ITP) is a complex autoimmune disorder in which the patient’s immune system reacts with platelet autoantigens resulting in immune-mediated platelet destruction and/or suppression of platelet production. Corticosteroids can induce sustained remission rates in 50% to 75% of patients with active ITP. For these patients who are unresponsive to glucocorticoids, or relapsed after an initial response, multiple second-line treatment modalities can be chosen. However, how to make an optimal therapeutic strategy for a specific patient still remains a major challenge. As the pathogenetic heterogeneity of the ITP is increasingly identified, pathogenesis-oriented approach might offer an opportunity to improve the outcome of corticosteroid-resistant or relapsed ITP.

B-cell-activating factor, a proliferation inducing ligand and co-stimulatory molecules in the pathogenesis of immune thrombocytopenia in childhood

The aim of this study was to measure the levels of B-cell-activating factor (BAFF), a proliferation-inducing ligand (APRIL), and co-stimulatory molecules in immune thrombocytopenia (ITP) of childhood to investigate the interaction between T and B lymphocytes and the impact of proliferation of B lymphocytes in the pathogenesis. Twenty newly diagnosed ITPs, 20 chronic ITPs, and 20 healthy controls between 2 and 18 years were enrolled in this study. Hemogram, BAFF, APRIL, interleukin-4, and interferon (IFN)-γ levels in sera and expressions of CD19, CD 3, CD21, CD40, and CD 154 on leukocytes were measured by ELISA and flow cytometry. Mean BAFF level in newly diagnosed ITP group was higher than the mean BAFF level in other groups. BAFF levels were significantly decreased after the treatment in newly diagnosed ITP group. APRIL, interleukin-4, and IFN-γ in newly diagnosed ITP group and BAFF, APRIL, interleukin-4, and IFN-γ in chronic ITP group were similar before and after treatment. There was no statistical difference for expressions of CD 19 and CD3 on lymphocytes, CD40 on leukocytes, CD154 on T cells, and for percentages of CD21/CD40, CD21/CD40, CD21/CD40 B cells, and CD19/CD3 lymphocytes for pretreatment and posttreatment levels in both ITP groups. In conclusion, our study strongly demonstrated that BAFF has an important role in the pathogenesis of newly diagnosed childhood ITP. It may be important in the follow-up and in novel therapy modalities of these patients.

Participation of B-cell-activating factor receptors in the pathogenesis of immune thrombocytopenia

ESSENTIALS: Dysfunctional B-cell-activating factor (BAFF) system is related to many autoimmune diseases. The regulatory functions of BAFF/BAFF receptors were investigated in an in vitro coculture system. Different regulatory roles of BAFF were investigated via different receptors in immune thrombocytopenia. The upregulated BAFF receptors on autoreactive lymphocytes lead to their hypersensitivity to BAFF.

SUMMARY

BACKGROUND

The pathogenesis of immune thrombocytopenia (ITP) remains enigmatic. B-cell-activating factor (BAFF) and its receptors (BAFF receptor [BAFF-R], transmembrane activator and calcium modulator and cyclophilin ligand interactor [TACI], and B-cell maturation antigen) play central roles in the integrated homeostatic regulation of lymphocytes.

OBJECTIVES

To investigate the pathologic roles of BAFF receptors in regulating the bioactivities of lymphocytes in ITP.

METHODS

An in vitro culture system was established by stimulating CD14(-) peripheral lymphocytes with platelet-preloaded dendritic cells in the presence of recombinant human BAFF (rhBAFF; 20 ng mL(-1)). The functions of BAFF receptors were specifically blocked with blocking antibodies.

RESULTS

BAFF-R, besides prolonging the survival of B cells in both patients and healthy controls, prominently promoted the survival of CD8(+) T cells and the proliferation of B cells in patients with ITP. TACI, as a positive regulator, not only promoted the proliferation of CD4(+) and CD8(+) T cells, but also significantly enhanced the secretion of interleukin-4 in patients with ITP, but not in controls. Besides revealing the pathologic roles of BAFF receptors, these results also indicate that lymphocytes of patients with ITP have enhanced antiapoptotic or proliferative capacity as compared with those from healthy controls when exposed under similar stimulation of rhBAFF. Further study demonstrated that activated autoreactive B cells and CD4(+) T cells from patients with ITP showed significantly higher expression of BAFF-R or TACI than those from healthy controls.

CONCLUSIONS

Both BAFF-R and TACI are pathogenic participants in ITP. Their dysregulated expression in patients with ITP may lead to hyperreactivity of activated autoreactive lymphocytes in response to rhBAFF, and thus is highly significant in the pathogenesis of ITP.

The effects of Jieduquyuzishen prescription-treated rat serum on the BAFF/BAFF-R signal pathway

Systemic lupus erythematosus (SLE) is a chronic inflammatory disease mainly characterized by B cell hyperactivity. Glucocorticoid (GC) is widely used in SLE for its potent anti-inflammatory and immunosuppressive effects. Despite its important clinical efficacy, high-dose or long-term use of GC can cause severe side effects, such as osteoporosis, osteonecrosis, cataracts, hyperglycemia, coronary heart disease and cognitive impairment. Our early clinical studies have shown that Jieduquyuzishen prescription (JP) can effectively reduce the adverse effects and improve the curative effect of GC in the treatment of SLE. The BAFF/BAFF-R signaling pathway plays an important role in the development of SLE and has been regarded as a potential target for the therapy of SLE. In this study, we attempt to investigate the effect of JP on the BAFF/BAFF-R signaling pathway to explore the mechanism of JP in reducing the toxicity and enhancing the efficacy of GC. YAC-1 cells, isolated rat peripheral blood lymphocytes, polymorphonuclear neutrophils and spleen lymphocytes were treated with drug-containing serum. The results of RT-PCR, Western blot and dual-luciferase reporter gene assays indicate that either JP or GC can inhibit the mBAFF-induced up-regulation of BAFF, BAFF-R, Bcl-2, IL-10 and NF-κB in YAC-1 cells and WEHI-231 cells. Furthermore, MTS, flow cytometry and CFSE results reveal that the proliferation and survival of lymphocytes activated by mBAFF are suppressed by JP, GC and their combination. Contrary to GC, JP can reduce the apoptosis and raise the survival of polymorphonuclear neutrophils and can’t increase the apoptosis of the peripheral blood lymphocytes and spleen lymphocytes. Therefore, it is possible that JP can down-regulate the BAFF/BAFF-R signaling pathway as effectively as GC, which may result in the dosage reduction of GC, thus decreasing the toxicity and improving the efficacy of GC-based treatment of SLE.

Genome-wide gene expression profiling reveals unsuspected molecular alterations in pemphigus foliaceus

Pemphigus foliaceus (PF) is a complex autoimmune disease characterized by bullous skin lesions and the presence of antibodies against desmoglein 1. In this study we sought to contribute to a better understanding of the molecular processes in endemic PF, as the identification of factors that participate in the pathogenesis is a prerequisite for understanding its biological basis and may lead to novel therapeutic interventions. CD4+ T lymphocytes are central to the development of the disease. Therefore, we compared genome-wide gene expression profiles of peripheral CD4+ T cells of various PF patient subgroups with each other and with that of healthy individuals. The patient sample was subdivided into three groups: untreated patients with the generalized form of the disease, patients submitted to immunosuppressive treatment, and patients with the localized form of the disease. Comparisons between different subgroups resulted in 135, 54 and 64 genes differentially expressed. These genes are mainly related to lymphocyte adhesion and migration, apoptosis, cellular proliferation, cytotoxicity and antigen presentation. Several of these genes were differentially expressed when comparing lesional and uninvolved skin from the same patient. The chromosomal regions 19q13 and 12p13 concentrate differentially expressed genes and are candidate regions for PF susceptibility genes and disease markers. Our results reveal genes involved in disease severity, potential therapeutic targets and previously unsuspected processes involved in the pathogenesis. Besides, this study adds original information that will contribute to the understanding of PF's pathogenesis and of the still poorly defined in vivo functions of most of these genes.

Immune thrombocytopenia and B-cell-activating factor/a proliferation-inducing ligand

Primary immune thrombocytopenia (ITP) is an organ-specific autoimmune disorder characterized by autoantibody-mediated enhanced platelet destruction and dysmegakaryocytopoiesis. B cells have been demonstrated to play critical roles in the pathophysiology of ITP. B-cell-activating factor (BAFF) and a proliferation-inducing ligand (APRIL) are crucial cytokines supporting survival and differentiation of B cells, and dysregulation of BAFF/APRIL is involved in the pathogenesis of B-cell related autoimmune diseases including ITP. Currently ongoing clinical trials using BAFF and/or APRIL-blocking agents have yielded positive results in human systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), further confirming the pathological role of BAFF/APRIL in autoimmunity. This review will describe the function of BAFF/APRIL and address the feasibility of BAFF/APRIL inhibition in the management of ITP.

BAFF expression correlates with idiopathic inflammatory myopathy disease activity measures and autoantibodies

OBJECTIVE

To investigate B cell survival cytokine messenger RNA (mRNA) levels as biomarkers of idiopathic inflammatory myopathies (IIM).

METHODS

We measured and compared mRNA levels of B cell survival cytokines by quantitative real-time polymerase chain reaction in 98 patients with IIM, 38 patients with systemic lupus erythematosus, and 21 healthy controls. The cytokines were B cell-activating factor belonging to the tumor necrosis factor family (BAFF); ΔBAFF; and a proliferation-inducing ligand (APRIL); and their receptors BAFF-R, transmembrane activator and calcium modulator and cyclophilin ligand interactor, and B cell maturation antigen (BCMA). We also identified autoantibodies, including anti-Sm, anti-RNP, anti-SSA/Ro, anti-SSB/La, anti-topoisomerase 1, anti-hystidyl-tRNA synthetase, anti-ribosomal P, and anti-chromatin. Clinical disease activity was assessed by the International Myositis Assessment and Clinical Studies core set tool. We examined correlation of mRNA with disease activity, medication use, and autoantibodies.

RESULTS

We found a positive correlation of BAFF and ΔBAFF expression with 3 disease activity measures, with ΔBAFF having a stronger correlation. Similarly, anti-SSA/Ro-52 and/or anti-SSA/Ro-60 had a strong positive correlation with mRNA levels of BAFF and ΔBAFF, and with relative ratios of BAFF/APRIL and BCMA/BAFF-R.

CONCLUSION

These findings highlight the potential importance of BAFF, ΔBAFF, and BAFF-R in the pathogenesis of IIM, and suggest an important role in the assessment of disease activity.

Single course of high dose dexamethasone is more effective than conventional prednisolone therapy in the treatment of primary newly diagnosed immune thrombocytopenia

INTRODUCTION

Immune thrombocytopenia (ITP) is an immune disorder commonly presents as isolated thrombocytopenia. Generally corticosteroids are the main treatment of ITP. This study was designed to evaluate effectiveness of high dose dexamethasone comparing conventional corticosteroid therapy in the treatment of ITP.

MATERIALS AND METHODS

In a randomized prospective study, sixty adult patients with newly diagnosed primary symptomatic ITP (Platelet count < 20,000) were evaluated. Patients divided into two groups. In group A, thirty patients (mean age of 24.9 years) received Dexamethasone 40 mg/IV/daily for four days (10 mg/q6h); and then Prednisolone 1 mg/kg/day/PO with rapid tapering of prednisolone (10 mg/week). From the other hand, in group B, thirty patients (mean age of 27.2 years) were treated with Prednisolone 1 mg/kg/day/PO for four weeks, then the drug tapered weekly.

RESULTS

All the patients in group A showed favorable response within the first seven days, 27 cases presented complete response (CR) and three cases revealed response (R). In group B, 11 cases had CR, 13 cases showed R and six cases had No response (NR). After three months, rates of CR were 80% and 23.3% in group A and B; respectively. Responses were 16.7% and 33.3%, NRs were 6.6% and 43.3% in group A and B; respectively (P < 0.0001). After 6 months, CR was 73.3% vs.16.7%, and R was 16.7% vs.36.7% and NR was 10% vs. 46.7% in group A and B; respectively (P < 0.0001). After 12 months, there was no change in response rate in group A, but in group B 53% were non responsive, 40% showed R (chronic ITP) and complete response was observed only in 6.7% (P < 0.0001). Three cases in group A and 12 cases in group B had needed splenectomy (P < 0.00002).

CONCLUSION

We showed that high dose dexamethasone is more effective than conventional steroid therapy in newly diagnosed ITP as initial treatment with less relapses and toxicities.

Pulsed high-dose dexamethasone improves interleukin 10 secretion by CD5+ B cells in patients with primary immune thrombocytopenia

BACKGROUND

B cells expressing CD5 are potentially capable of producing interleukin 10 (IL-10) which contributes to the regulatory function of B cells. This study was aimed at exploring the alteration of numbers of CD5(+) B cells and their ability of producing IL-10 in patients with immune thrombocytopenia (ITP), and the effects of pulsed high-dose dexamethasone (HD-DXM) therapy on CD5(+) B cells.

METHODS

Peripheral blood mononuclear cells from 25 adult ITP patients were stained with PE-CD5/FITC-CD19 antibodies for flow cytometry analyses before and after HD-DXM therapy. The expression of IL-10 mRNA was measured by RT-PCR. After 24 h culture with or without dexamethasone in the presence of PMA, ionomycin and Brefeldin A, cells were permeabilized and stained with APC-IL-10 antibody to investigate intracellular IL-10 expression. Supernatant IL-10 concentration was detected by ELISA.

RESULTS

The number of CD5(+) B cells was elevated in patients with ITP. Expression of IL-10 mRNA, percentage of IL-10(+) cells and intracellular IL-10 in CD5(+) B cells from untreated patients were significantly higher than that in controls. In contrast, ITP patients showed lower IL-10 concentration in supernatants than controls. After HD-DXM therapy, the number of CD5(+) B cells decreased to normal level, while intracellular IL-10 expression in CD5(+) B cells was further enhanced and IL-10 concentration in supernatants was also increased. Similar results were observed when dexamethasone was administrated in vitro.

CONCLUSIONS

Increased number of CD5(+) B cells in which IL-10 is accumulated with decreased IL-10 concentration in supernatants suggests that the ability of CD5(+) B cells to secret IL-10 is impaired in ITP patients. Both the aberrant number and ability of IL-10 secretion of CD5(+) B cells could be corrected by HD-DXM.

Piecing together the humoral and cellular mechanisms of immune thrombocytopenia

The precise mechanisms leading to platelet-targeted autoimmunity in immune thrombocytopenia (ITP) are not known. Cellular checkpoints normally regulate immunological self-reactivity during the development of B and T cells through cell deletion, receptor editing, induction of anergy, and extrinsic cellular suppression. When these checkpoints fail, tolerance to self-antigens may be lost. In this review, we summarize the various immune mechanisms contributing to the development of ITP and relate them back to the checkpoint model of autoimmunity. These mechanisms, including increased levels of lymphocyte growth factors, resistance to death signals, and loss of T-regulatory function, result in an environment permissive to the development of platelet-reactive B and T cells. The mechanisms that lead to thrombocytopenia once tolerance for platelet antigens is lost are examined, including complement-dependent and apoptotic pathways. An improved understanding of ITP pathogenesis will ultimately guide the development of better therapies.

Lipopolysaccharide renders transgenic mice expressing human serum amyloid P component sensitive to Shiga toxin 2

Transgenic C57BL/6 mice expressing human serum amyloid P component (HuSAP) are resistant to Shiga toxin 2 (Stx2) at dosages that are lethal in HuSAP-negative wild-type mice. However, it is well established that Stx2 initiates extra-intestinal complications such as the haemolytic-uremic syndrome despite the presence of HuSAP in human sera. We now demonstrate that co-administering purified Escherichia coli O55 lipopolysaccharide (LPS), at a dosage of 300 ng/g body weight, to HuSAP-transgenic mice increases their susceptibility to the lethal effects of Stx2. The enhanced susceptibility to Stx2 correlated with an increased expression of genes encoding the pro-inflammatory cytokine TNFα and chemokines of the CXC and CC families in the kidneys of LPS-treated mice, 48 hours after the Stx2/LPS challenge. Co-administering the glucocorticoid dexamethasone, but not the LPS neutralizing cationic peptide LL-37, protected LPS-sensitized HuSAP-transgenic mice from lethal doses of Stx2. Dexamethasone protection was specifically associated with decreased expression of the same inflammatory mediators (CXC and CC-type chemokines and TNFα) linked to enhanced susceptibility caused by LPS. The studies reveal further details about the complex cascade of host-related events that are initiated by Stx2 as well as establish a new animal model system in which to investigate strategies for diminishing serious Stx2-mediated complications in humans infected with enterohemorrhagic E. coli strains.

Recent progress in understanding the pathogenesis of immune thrombocytopenia

PURPOSE OF REVIEW

Immune thrombocytopenia (ITP) is a bleeding disorder in which both antibody and cell-mediated autoimmune responses are directed against an individual's own platelets and/or megakaryocytes, leading to either enhanced platelet destruction and/or reduced platelet production, respectively. The cause of this platelet-specific autoimmunity remains unknown, but there has been a constant stream of recent publications that suggest ITP is the result of T-cell dysregulation.

RECENT FINDINGS

In the last 18 months, a rich tapestry of studies has emerged that seems to clarify some immunopathologic issues in ITP while raising new questions related to ITP pathogenesis. The current view on the immunopathogenic mechanisms associated with ITP appears to particularly concentrate on how incompetent CD4+ T-regulatory cells (Tregs) allow autoimmune effector mechanisms to proceed and cause thrombocytopenia. There is a parallel body of recent literature focusing on molecular mimicry mechanisms, B-cell abnormalities, abnormal cytokine patterns and genetic studies in ITP. Of interest, one can recognize inter-relationships between these immune dysregulations.

SUMMARY

This article will discuss the literature from the past 18 months pertaining to these observations and will show that whereas many of the T-cell defects have been clarified, new questions have also come to light and more immunopathological research is warranted.

Susceptibility to experimental autoimmune encephalomyelitis is associated with altered B-cell subsets distribution and decreased serum BAFF levels

B cells possess the ability to regulate either pathogenic or protective events in several autoimmune diseases such as multiple sclerosis (MS) and its experimental model, experimental autoimmune encephalomyelitis (EAE). Given the extensive use of B-cell-targeting treatments, it appears crucial to more precisely define the dual role of B cells in the progression of the disease. In the present study, we explored the impact of EAE induction on the distribution of potential regulatory B-cell subsets (CD5(+) B1a, marginal zone and transitional 2 B cells) over critical time points in the relapsing-remitting EAE model, SJL/J (H2s). The same approach was carried out in B10.S mice that are resistant to EAE induction, (H2s). The comparative data obtained from these experiments showed that the homeostasis of the regulatory B-cell subsets is altered during the EAE preclinical and acute phases. These observations were associated with a distortion of the BAFF response. All these data suggest the existence of a close relationship between B-cell homeostasis, BAFF response and the susceptibility to develop EAE.