Comparison of bone mineral density changes between male and female osteoporosis patients using dual energy X-ray absorptiometry scan

The goal of the current research was to define the impact of individual characteristics on the response of osteoporosis patients to bisphosphonate medication, as well as the influence of gender on changes in the bone mineral density (BMD).The DXA scan was used to assess a group of 647 osteoporosis patients (533 females and 114 males) who visited the St Bartholomew's Hospitals and Royal London osteoporosis clinics. All male subjects received statistically substantial increases in BMD relative to baseline values after two years of therapy. When compared to prior therapy, men's BMD of the lumbar spine (LS) and hip joint (HJ) rose by 0.057 g/cm² (6.9%, p0.001) and 0.021 g/cm² (2.48 percent, p0.001), respectively.. Female patients had BMD changes of 0.028 g/cm² (3.58 percent, p0.001 vs. prior therapy) and -0.006 g/cm² (-0.78 percent, p0.001 vs. before treatment) in the lumbar spine and hip, respectively. Male patients exhibited a greater increase in BMD than female patients due to ovarian failure and significant oestrogen loss, which speeds up bone resorption by 90% following menopause, according the research findings.

Metabolic requirements of Th17 cells and of B cells: Regulation and defects in health and in inflammatory diseases

The immune system protects from infections and cancer through complex cellular networks. For this purpose, immune cells require well-developed mechanisms of energy generation. However, the immune system itself can also cause diseases when defective regulation results in the emergence of autoreactive lymphocytes. Recent studies provide insights into how differential patterns of immune cell responses are associated with selective metabolic pathways. This review will examine the changing metabolic requirements of Th17 cells and of B cells at different stages of their development and activation. Both cells provide protection but can also mediate diseases through the production of autoantibodies and the production of proinflammatory mediators. In health, B cells produce antibodies and cytokines and present antigens to T cells to mount specific immunity. Th17 cells, on the other hand, provide protection against extra cellular pathogens at mucosal surfaces but can also drive chronic inflammation. The latter cells can also promote the differentiation of B cells to plasma cells to produce more autoantibodies. Metabolism-regulated checkpoints at different stages of their development ensure the that self-reactive B cells clones and needless production of interleukin (IL-)17 are limited. The metabolic regulation of the two cell types has some similarities, e.g. the utility of hypoxia induced factor (HIF)1α during low oxygen tension, to prevent autoimmunity and regulate inflammation. There are also clear differences, as Th17 cells only are vulnerable to the lack of certain amino acids. B cells, unlike Th17 cells, are also dependent of mechanistic target of rapamycin 2 (mTORC2) to function. Significant knowledge has recently been gained, particularly on Th17 cells, on how metabolism regulates these cells through influencing their epigenome. Metabolic dysregulation of Th17 cells and B cells can lead to chronic inflammation. Disease associated alterations in the genome can, in addition, cause dysregulation to metabolism and, thereby, result in epigenetic alterations in these cells. Recent studies highlight how pathology can result from the cooperation between the two cell types but only few have so far addressed the key metabolic alterations in such settings. Knowledge of the impact of metabolic dysfunction on chronic inflammation and pathology can reveal novel therapeutic targets to treat such diseases.

Disease status in human and experimental arthritis, and response to TNF blockade, is associated with MHC class II invariant chain (CD74) isoform expression

Splice variants of CD74 differentially modulate the activity of cathepsin L (CTSL). As CD74 and CTSL participate in the pathogenesis of inflammatory diseases such as rheumatoid arthritis (RA), we determined whether splice variants of CD74 could be biomarkers of disease activity. Gene expression was measured in mice with collagen-induced arthritis using quantitative PCR (qPCR). In vitro studies using murine macrophage/DC-lineage cells determined the relative influence of macrophage phenotype on isoform expression and the potential to produce CTSL in response to TNF. CD74 splice variants were measured in human RA synovium and RA patients' monocytes. In arthritic mice, the expression of the p41 CD74 isoform was significantly higher in severely affected paws compared with unaffected paws or the paws of naïve mice; the p41 isoform significantly correlated with the expression of TNF in arthritic paws. Compared with M2-like macrophages, M1-like macrophages expressed increased levels of CD74 and had higher expression, secretion and activity of CTSL. RA patients that responded to TNF blockade had significantly higher expression levels of CD74 in circulating monocytes after treatment, compared with non-responders. The expression of the human CD74 isoform a was significantly higher in RA synovia, compared with osteoarthritis synovia, and was associated with CSTL enzymatic activity. This study is the first to demonstrate differential expression of the CD74 p41 isoform in an auto-immune disorder and in response to therapy. The differential expression of CD74 splice variants indicates an association, and potentially a mechanistic role, in the pathogenesis of RA.

Dysregulated B cell function and disease pathogenesis in systemic sclerosis

Systemic sclerosis (SSc) is a complex, immune-mediated rheumatic disease characterised by excessive extracellular matrix deposition in the skin and internal organs. B cell infiltration into lesional sites such as the alveolar interstitium and small blood vessels, alongside the production of defined clinically relevant autoantibodies indicates that B cells play a fundamental role in the pathogenesis and development of SSc. This is supported by B cell and fibroblast coculture experiments revealing that B cells directly enhance collagen and extracellular matrix synthesis in fibroblasts. In addition, B cells from SSc patients produce large amounts of profibrotic cytokines such as IL-6 and TGF-β, which interact with other immune and endothelial cells, promoting the profibrotic loop. Furthermore, total B cell counts are increased in SSc patients compared with healthy donors and specific differences can be found in the content of naïve, memory, transitional and regulatory B cell compartments. B cells from SSc patients also show differential expression of activation markers such as CD19 which may shape interactions with other immune mediators such as T follicular helper cells and dendritic cells. The key role of B cells in SSc is further supported by the therapeutic benefit of B cell depletion with rituximab in some patients. It is notable also that B cell signaling is impaired in SSc patients, and this could underpin the failure to induce tolerance in B cells as has been shown in murine models of scleroderma.

TNFα inhibitors reduce bone loss in rheumatoid arthritis independent of clinical response by reducing osteoclast precursors and IL-20

OBJECTIVES

About half of RA patients treated with TNFα inhibitors either do not respond or lose their initial therapeutic response over time. The clinical response is measured by reduction in DAS28, which primarily reflects inflammation. However, other effects of TNFα inhibitors, such as impact on bone erosion, are not assessed by DAS28. We aimed to examine the effect of TNFα inhibitors on bone density, bone biomarkers and cytokine production in responder and non-responder patients and assessed mechanisms of action.

METHODS

BMD in the lumbar spine and femur neck of 117 RA patients was measured by DEXA scan. Bone turnover biomarkers CTX, osteoprotegerin (OPG), osteocalcin and RANKL were measured by ELISA. Levels of 16 cytokines in plasma and in tissue culture supernatants of ex vivo T cells were measured by multiplex assays and ELISA. The effect of treatment with TNFα inhibitors on blood mononuclear cell (MNC) differentiation to osteoclast precursors (OCP) was measured flow cytometry and microscopy.

RESULTS

TNFα inhibitors improved lumbar spine BMD but had modest effects on blood bone biomarkers, irrespective of patients' clinical response. Blood OCP numbers and the ability of monocytes to differentiate to OCP in vitro declined after treatment. Treatment also reduced RANK expression and IL-20 production. BMD improvement correlated with reduced levels of IL-20 in responder patients.

CONCLUSION

This study reveals that TNFα inhibitors reduce lumbar spine bone loss in RA patients irrespective of changes in DAS28. The reduction in bone loss is associated with reduction in IL-20 levels in responder patients.

Functional and phenotypic heterogeneity of Th17 cells in health and disease

BACKGROUND

Th17 cells have nonredundant roles in maintaining immunity, particularly at mucosal surfaces. These roles are achieved principally through the production of cytokines and the recruitment of other immune cells to maintain the integrity of mucosal barriers and prevent the dissemination of microorganisms. Th17 cells are heterogeneous and exhibit a considerable degree of plasticity. This allows these cells to respond to changing environmental challenges. However, Th17 cells also play pro-inflammatory roles in chronic autoimmune diseases. The trigger(s) that initiate these Th17 responses in chronic autoimmune diseases remain unclear.

DESIGN

In this report, we provide an overview of studies involving animal models, patient data, genome wide association studies and clinical trials targeting IL-17 for treatment of patients to gain a better understanding of the pathogenic roles of Th17 cells play in a range of autoimmune diseases.

RESULTS

The report sheds light on likely triggers that initiate or perpetuate Th17 responses that promote chronic inflammation and autoimmunity. The divergent effects of tumour necrosis factor alpha blockade on Th17 cells in patients, is explored. Furthermore, we highlight the role of Th17 cells in inducing autoreactive B cells, leading to autoantibody production. Pathogenic bacterial species can change Th17 cell phenotype and responses. These findings provide insights into how Th17 cells could be induced to promoting autoimmune disease pathogenesis.

CONCLUSION

This article provides an overview of the distinct roles Th17 cells play in maintaining immunity at mucosal surfaces and in skin mucosa and how their functional flexibility could be linked with chronic inflammation in autoimmune rheumatic diseases.

Association of Defective Regulation of Autoreactive Interleukin-6-Producing Transitional B Lymphocytes With Disease in Patients With Systemic Sclerosis

OBJECTIVE

Systemic sclerosis (SSc) has the highest case-specific mortality of any rheumatic disease, and no effective therapy is available. A clear manifestation of SSc is the presence of autoantibodies. However, the origin of autoantibody-producing B lymphocytes, their mechanisms of activation and autoantibody production, and their role remain unclear. This study was undertaken to identify mechanisms that contribute to pathogenic B cell generation and involvement in SSc and to assess the altered distribution and function of B cells in SSc patients.

METHODS

Multicolor flow cytometry was performed to determine B cell subset distribution, cytokine production, and tolerance induction in SSc patients and healthy controls. Cytokine production following stimulation of the cells ex vivo was determined by multiplex assay.

RESULTS

A range of defects in B lymphocyte tolerance and cytokine production in SSc were noted. There was evidence of altered distribution of transitional B cell subsets, increased production of interleukin-6 (IL-6) and IL-8, and defective tolerance induction in SSc B cells. In addition, B cells from SSc patients had a reduced ability to produce IL-10 when stimulated through innate immune pathways. In contrast to healthy individuals, tolerance checkpoints in SSc patients failed to suppress the emergence of B cells that produce autoantibodies with specificity to the Scl-70 antigen, which is strongly associated with SSc. These defects were paralleled by altered intracellular signaling and apoptosis following B cell receptor engagement.

CONCLUSION

Our findings provide new insights into mechanisms underlying defective B lymphocyte responses in patients with SSc and their contribution to disease.

Intracellular B Lymphocyte Signalling and the Regulation of Humoral Immunity and Autoimmunity

B lymphocytes are critical for effective immunity; they produce antibodies and cytokines, present antigens to T lymphocytes and regulate immune responses. However, because of the inherent randomness in the process of generating their vast repertoire of antigen-specific receptors, B cells can also cause diseases through recognizing and reacting to self. Therefore, B lymphocyte selection and responses require tight regulation at multiple levels and at all stages of their development and activation to avoid diseases. Indeed, newly generated B lymphocytes undergo rigorous tolerance mechanisms in the bone marrow and, subsequently, in the periphery after their migration. Furthermore, activation of mature B cells is regulated through controlled expression of co-stimulatory receptors and intracellular signalling thresholds. All these regulatory events determine whether and how B lymphocytes respond to antigens, by undergoing apoptosis or proliferation. However, defects that alter regulated co-stimulatory receptor expression or intracellular signalling thresholds can lead to diseases. For example, autoimmune diseases can result from altered regulation of B cell responses leading to the emergence of high-affinity autoreactive B cells, autoantibody production and tissue damage. The exact cause(s) of defective B cell responses in autoimmune diseases remains unknown. However, there is evidence that defects or mutations in genes that encode individual intracellular signalling proteins lead to autoimmune diseases, thus confirming that defects in intracellular pathways mediate autoimmune diseases. This review provides a synopsis of current knowledge of signalling proteins and pathways that regulate B lymphocyte responses and how defects in these could promote autoimmune diseases. Most of the evidence comes from studies of mouse models of disease and from genetically engineered mice. Some, however, also come from studying B lymphocytes from patients and from genome-wide association studies. Defining proteins and signalling pathways that underpin atypical B cell response in diseases will help in understanding disease mechanisms and provide new therapeutic avenues for precision therapy.

Response to Treatment with TNFα Inhibitors in Rheumatoid Arthritis Is Associated with High Levels of GM-CSF and GM-CSF+ T Lymphocytes

Biologic TNFα inhibitors are a mainstay treatment option for patients with rheumatoid arthritis (RA) refractory to other treatment options. However, many patients either do not respond or relapse after initially responding to these agents. This study was carried out to identify biomarkers that can distinguish responder from non-responder patients before the initiation of treatment. The level of cytokines in plasma and those produced by ex vivo T cells, B cells and monocytes in 97 RA patients treated with biologic TNFα inhibitors was measured before treatment and after 1 and 3 months of treatment by multiplex analyses. The frequency of T cell subsets and intracellular cytokines were determined by flow cytometry. The results reveal that pre-treatment, T cells from patients who went on to respond to treatment with biologic anti-TNFα agents produced significantly more GM-CSF than non-responder patients. Furthermore, immune cells from responder patients produced higher levels of IL-1β, TNFα and IL-6. Cytokine profiling in the blood of patients confirmed the association between high levels of GM-CSF and responsiveness to biologic anti-TNFα agents. Thus, high blood levels of GM-CSF pre-treatment had a positive predictive value of 87.5% (61.6 to 98.5% at 95% CI) in treated RA patients. The study also shows that cells from most anti-TNFα responder patients in the current cohort produced higher levels of GM-CSF and TNFα pre-treatment than non-responder patients. Findings from the current study and our previous observations that non-responsiveness to anti-TNFα is associated with high IL-17 levels suggest that the disease in responder and non-responder RA patients is likely to be driven/sustained by different inflammatory pathways. The use of biomarker signatures of distinct pro-inflammatory pathways could lead to evidence-based prescription of the most appropriate biological therapies for different RA patients.

Favorable therapeutic response of osteoporosis patients to treatment with intravenous zoledronate compared with oral alendronate

Objectives:

To evaluate the efficacy of orally-administered alendronate compared with intravenously-administered zoledronate.

Methods:

This prospective study was carried out at Barts Health HNS Trust between April 2010 and March 2012. This study compares changes in bone mineral density (BMD) in 234 patients treated with 2 bisphosphonates: alendronate taken orally, and zoledronate administered intravenously. One hundred and eighteen patients received alendronate at 70 mg/week, while 116 patients received zoledronate once annually. Dual energy x-ray absorptiometry was used to measure BMD of the left hip and anterior-posterior spine (lumbar L1-L4) skeletal sites at baseline, and at one-, and 2-years post-treatment.

Results:

This study provides evidence that lumbar spine BMD increased by 3.6% in patients receiving alendronate, and 5.7% in patients receiving zoledronate after 2 years compared with baseline values (p=0.0001 for both). Total hip BMD decreased in patients treated with alendronate by 0.4% but increased in patients receiving zoledronate by 0.8% (p=0.0001).

Conclusion:

This study provides evidence that zoledronate is more effective than alendronate in treating patients with osteoporosis and with no gastrointestinal (GI) serious side effects. Furthermore, zoledronate appears to have the added advantage of a better safety profile in patients suffering from GI intolerance of oral bisphosphonates.

TNFα in the regulation of Treg and Th17 cells in rheumatoid arthritis and other autoimmune inflammatory diseases

TNFα is a principal pro-inflammatory cytokine vital for immunity to infections. However, its excessive production is involved in chronic inflammation and disease pathology in autoimmune diseases. Evidence for its pathogenic role is validated by the fact that its neutralisation by therapeutic agents in vivo is beneficial in ameliorating disease and controlling symptoms. Paradoxically, however, treatment with TNFα inhibitors can either have no clinical effects, or even exacerbate disease in some patients. The explanation for such contradictory outcomes may lay in how and which downstream signalling pathways are activated and drive disease. TNFα causes its effects by binding to either or both of two membrane-bound receptors, TNFR1 and TNFR2. Engagement of the receptors can induce cell death or cell proliferation. T cells both produce and respond to TNFα and depending on whether the cytokine is membrane-bound or soluble and the level of expression of its two receptors, the biological outcome can be distinct. In addition, polymorphisms in genes encoding TNFα and T cell signalling proteins can significantly impact the outcome of TNFα receptor engagement. Early studies revealed that effector T cells in patients with rheumatoid arthritis (RA) are hyporesponsive due to chronic exposure to TNFα. However, recent evidence indicates that the relationship between TNFα and T cell responses is complex and, at times, can be paradoxical. In addition, there is controversy as to the specific effects of TNFα on different T cell subsets. This review will summarise knowledge on how TNFα modulates T cell responses and the effect of engaging either of its two receptors. Furthermore, we discuss how such interactions can dictate the outcome of treatment with TNFα inhibitors.

CD5 expression promotes IL-10 production through activation of the MAPK/Erk pathway and upregulation of TRPC1 channels in B lymphocytes

CD5 is constitutively expressed on T cells and a subset of mature normal and leukemic B cells in patients with chronic lymphocytic leukemia (CLL). Important functional properties are associated with CD5 expression in B cells, including signal transducer and activator of transcription 3 activation, IL-10 production and the promotion of B-lymphocyte survival and transformation. However, the pathway(s) by which CD5 influences the biology of B cells and its dependence on B-cell receptor (BCR) co-signaling remain unknown. In this study, we show that CD5 expression activates a number of important signaling pathways, including Erk1/2, leading to IL-10 production through a novel pathway independent of BCR engagement. This pathway is dependent on extracellular calcium (Ca²⁺) entry facilitated by upregulation of the transient receptor potential channel 1 (TRPC1) protein. We also show that Erk1/2 activation in a subgroup of CLL patients is associated with TRPC1 overexpression. In this subgroup of CLL patients, small inhibitory RNA (siRNA) for CD5 reduces TRPC1 expression. Furthermore, siRNAs for CD5 or for TRPC1 inhibit IL-10 production. These findings provide new insights into the role of CD5 in B-cell biology in health and disease and could pave the way for new treatment strategies for patients with B-CLL.

Bone loss in osteoporosis and arthritis. Pathogenesis and therapeutic strategies

Bone makes up a framework that provides protection for internal body organs. The homeostasis of bone is maintained by balanced old bone resorption and new bone formation. However, this balance can be altered such as in postmenopausal women, patients with some cancers, and patients with chronic inflammatory conditions such as rheumatoid arthritis. In recent years, the management of chronic inflammatory conditions was revolutionized by the use of biologic therapies that target key pro-inflammatory proteins and/or pathways. However, whilst the anti-inflammatory effect of these biologic agents is well-established, their effect on bone loss is just emerging. The use of these agents highlights the relationship between the pathogenesis of chronic inflammation and bone loss. Here, we provide an overview of advances in understanding this relationship in patients with rheumatoid arthritis.

Aberrant B-lymphocyte responses in lupus: inherent or induced and potential therapeutic targets

BACKGROUND

Lupus is a prototype autoimmune disease of unknown aetiology. The disease is complex; manifest diverse clinical symptoms and disease mechanisms. This complexity has provided many leads to explore: from disease mechanisms to approaches for therapy. B-lymphocytes play a central role in the pathogenesis of the disease. However, the cause of aberrant B-lymphocyte responses in patients and, indeed, its causal relationship with the disease remain unclear.

DESIGN

This article provides a synopsis of current knowledge of immunological abnormalities in lupus with an emphasis on abnormalities in the B-lymphocyte compartment.

RESULTS

There is evidence for abnormalities in most compartments of the immune system in animal models and patients with lupus including an ever expanding list of abnormalities within the B-lymphocyte compartment. In addition, recent genome-wide linkage analyses in large cohorts of patients have identified new sets of genetic association factors some with potential links with defective B-lymphocyte responses although their full pathophysiological effects remain to be determined. The accumulating knowledge may help in the identification and application of new targeted therapies for treating lupus disease.

CONCLUSIONS

Cellular, molecular and genetic studies have provided significant insights into potential causes of immunological defects associated with lupus. Most of this insight relate to defects in B- and T-lymphocyte tolerance, signalling and responses. For B-lymphocytes, there is evidence for altered regulation of inter and intracellular signalling pathways at multiple levels. Some of these abnormalities will be discussed within the context of potential implications for disease pathogenesis and targeted therapies.

B-lymphocyte signalling abnormalities and lupus immunopathology

Lupus is a complex autoimmune rheumatic disease of unknown aetiology. The disease is associated with diverse features of immunological abnormality in which B-lymphocytes play a central role. However, the cause of atypical B-lymphocyte responses remains unclear. In this article, we provide a synopsis of current knowledge on intracellular signalling abnormalities in B-lymphocytes in lupus and their potential effects on the response of these cells in mouse models and in patients. There are numerous reported defects in the regulation of intracellular signalling proteins and pathways in B-lymphocytes in lupus that, potentially, affect critical biological responses. Most of the evidence for these defects comes from studies of disease models and genetically engineered mice. However, there is also increasing evidence from studying B-lymphocytes from patients and from genome-wide linkage analyses for parallel defects to those observed in mice. These studies provide molecular and genetic explanations for the key immunological abnormalities associated with lupus. Most of the new information appears to relate to defects in intracellular signalling that impact B-lymphocyte tolerance, cytokine production and responses to infections. Some of these abnormalities will be discussed within the context of disease pathogenesis.

Altered patterns of epigenetic changes in systemic lupus erythematosus and auto-antibody production: is there a link?

The prominent feature of immunological defects in systemic lupus erythematosus (SLE) is the production of autoantibodies (auto-Abs) to nuclear antigens including DNA, histones and RNP. In addition, there is growing evidence that epigenetic changes play a key role in the pathogenesis of SLE. Autoreactive CD4(+) T cells and B cells in patients with SLE have evidence of altered patterns of DNA methylation as well as post-translational modifications of histones and ribonucleoproteins (RNP). A key question that has emerged from these two characteristic features of SLE is whether the two processes are linked. New data provide support for such a link. For example, there is evidence that hypomethylated DNA is immunogenic, that anti-histone auto-Abs in patients with SLE bind epigenetic-sensitive hot spots and that epigenetically-modified RNP-derived peptides can modulate lupus disease. All in all, the available evidence indicates that a better understanding of dysregulation in epigenetics in SLE may offer opportunities to develop new biomarkers and novel therapeutic strategies.

CD5 promotes IL-10 production in chronic lymphocytic leukemia B cells through STAT3 and NFAT2 activation

B lymphocytes from chronic lymphocytic leukemia (CLL) display some CD5 transcripts for CD5 containing the known exon 1 (E1A) and other CD5 transcripts containing the new exon 1 (E1B). These malignant B cells, as well as B cell lines transfected with cDNA for E1A-cd5 or with cDNA for E1B-cd5 produce IL-10, raising the possibility that CD5 participates in the secretion of IL-10. We identified transcription factors involved in this production in CD5(+) B lymphocytes from CLL patients and in E1A-cd5-transfected or E1B-cd5-transfected Jok cells. STAT3 is activated via phosphorylation of serine 727 but also NFAT2 through its translocation into the nucleus. Chromatin immunoprecipitation experiments confirmed the role of STAT3 and allowed the discovery of a role for NFAT2 in IL-10 production. Both transcription factors bind not only to the enhancer of the Il-10 gene but also to the promoter of the Il-5 and Il-13 genes. Furthermore, transfection of B cell lines with E1A-cd5 or E1B-cd5 established that activation of STAT3 and NFAT2 is regulated by CD5. The same holds true for the production of IL-10, IL-5, and IL-13 and the expression of the receptors for these cytokines. This interpretation was confirmed by two experiments. In the first, downregulation of CD5 by small interfering RNAs lowered the production of IL-10. In the second experiment, transfection of the GFP-NFAT2 gene into B lymphocytes induced nuclear translocation of NFAT2 in CD5(+) but not in CD5(-) B cells. Thus, CD5 expression is associated with NFAT2 activity (and mildly STAT3 activity), indicating that CD5 controls IL-10 secretion.

Protein phosphorylation and kinome profiling reveal altered regulation of multiple signaling pathways in B lymphocytes from patients with systemic lupus erythematosus

OBJECTIVE

The cause of B lymphocyte hyperactivity and autoantibody production in systemic lupus erythematosus (SLE) remains unclear. Previously, we identified abnormalities in the level and translocation of signaling molecules in B cells in SLE patients. The present study was undertaken to examine the extent of signaling abnormalities that relate to altered B cell responses in SLE.

METHODS

B lymphocytes from 88 SLE patients and 72 healthy controls were isolated from blood by negative selection. Protein tyrosine phosphorylation and cellular kinase levels were analyzed by Western blotting, flow cytometry, and a kinome array protocol. Changes in protein phosphorylation were determined in ex vivo B cells and following B cell receptor engagement.

RESULTS

Differences in tyrosine phosphorylation in B cells from patients with SLE, compared with matched controls, were demonstrated. Further, the kinome array analysis identified changes in the activation of key kinases, i.e., the activity of phosphatidylinositol 3-kinase, which regulates survival and differentiation, was up-regulated and the activity of Rac and Rho kinases, which regulate the cytoskeleton and migration, was increased. In contrast, the activity of ATR, which regulates the cell cycle, was down-regulated in SLE patients compared with controls. Differences in signaling pathways were seen in all SLE B lymphocyte subsets that manifested phenotypic features of immature, mature, and memory cells.

CONCLUSION

This study revealed dysregulation in multiple signaling pathways that control key responses in B cells of SLE patients. Data generated in this study provide a molecular basis for further analysis of the altered B lymphocyte responses in SLE.

IL-10 production by B cells expressing CD5 with the alternative exon 1B

B lymphocytes are divided into two subpopulations, B1 and B2 cells based on expression of the T cell-associated protein CD5. Natural B1 cells are further divided into B1a cells that express CD5 on their membrane and B1b cells that do not but share most other biological characteristics of B1a cells. Recent studies from our laboratory have revealed, in humans, the existence of two alternative isoforms of the CD5 protein. A cell surface CD5 isoform which uses exon 1A (E1A) of the gene in B1a cells, and an intracellular isoform which uses exon 1B (E1B) mainly in human B1b cells. Indeed, the protein isoform encoded by transcripts containing E1B lack the leader peptide and is, thus, retained in the cytoplasm of B cells. The restriction of interleukin (IL)-10 to B1 lymphocytes in the mouse raises the possibility that the human CD5-E1B-expressing B cells produce IL-10. This prediction was confirmed in the CD5 negative Jok-1 B cells transfected with cDNA for either isoforms resulted in high level IL-10 production. Our data indicate that E1B-CD5-expressing B cells have the capacity to interfere with the immune response through their ability to produce high levels of IL-10.

Transmembrane BAFF from rheumatoid synoviocytes requires interleukin-6 to induce the expression of recombination-activating gene in B lymphocytes

OBJECTIVE

B cells that accumulate in the synovial tissue of rheumatoid arthritis (RA) patients revise their receptors due to coordinate expression of recombination-activating gene 1 (RAG-1) and RAG-2 genes. The aim of this study was to determine the mechanisms that control this re-expression.

METHODS

B cells from healthy control subjects were cocultured with fibroblast-like synoviocytes (FLS) from patients with RA and osteoarthritis (OA). Re-expression of RAG messenger RNA (mRNA) and proteins was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and indirect immunofluorescence. Activity of RAG enzymes was evaluated by flow cytometry to measure variations in immunoglobulin kappa and lambda light chain expression and by ligation-mediated-PCR to assess specific DNA breaks. Blocking antibodies, short hairpin RNA, and recombinant cytokine were used to identify the molecules involved in RAG re-expression.

RESULTS

RA FLS, but not OA FLS, induced B cells to re-express RAG mRNA and proteins. Enzymes were functional, since the kappa-to-lambda ratios decreased and specific DNA breaks were detectable after coculture with RA FLS. Transmembrane BAFF provided the first signal of RAG re-expression, since its down-regulation in RA FLS prevented RAG gene transcription in B cells. The failure of transmembrane BAFF from OA FLS to induce RAG suggests that a second signal was provided by RA FLS. Interleukin-6 (IL-6) is a candidate, since blockade of its receptors precluded transcription of RAG genes by RA FLS. Unless supplemented with IL-6, OA FLS were unable to induce RAG gene expression in normal B cells.

CONCLUSION

Two independent signals are required for the induction of RAG gene expression in B cells that infiltrate the synovium of patients with RA.

IL-6 modulates CD5 expression in B cells from patients with lupus by regulating DNA methylation

B lymphocytes from patients with systemic lupus erythematosus (SLE) are characterized by reduced expression levels of membrane CD5. Recent studies from our laboratory have revealed that the level of membrane CD5 is determined by the relative level of two alternative CD5 isoforms; CD5-E1A, which is expressed on the membrane, and CD5-E1B, which is retained in the cytoplasm. Using bisulfite sequencing and methylation-sensitive endonuclease assays we show that the promoter for the alternative CD5-E1B isoform is demethylated in B cells from patients with SLE but not in healthy controls. We go on to show that differential methylation is more pronounced following BCR engagement. As a result of this demethylation, CD5-E1B mRNA is transcribed at the expense of CD5-E1A mRNA transcription. We provide further evidence that production of high IL-6 levels by SLE B cells abrogates the ability of SLE B cells to induce DNA methyl transferase (DNMT1) and then to methylate DNA, an effect that is reversed in the presence of a blocking Ab to the IL-6 receptor. The pattern of demethylation of CpG islands in the CD5-E1B promoter in SLE B cells is similar to those in B cells from healthy controls stimulated in the presence of IL-6, or treated with the methylation inhibitor PD98059. The study reveals that engagement of the BCR with constitutive IL-6 down-regulates the level of membrane CD5, which negatively regulates BCR signaling, in SLE B cells. This altered signaling could, in turn, promote the activation and expansion of autoreactive B cells in SLE patients.

Mitochondrial heat shock protein (HSP) 70 synergizes with HSP60 in transducing endothelial cell apoptosis induced by anti-HSP60 autoantibody

Heat shock protein (HSP) 60, up-regulated by endothelial cells (ECs) to resist stress, is the target of a subgroup of apoptosis-inducing anti-EC autoantibodies (Abs) in human vasculitides. Given that HSP60 is not a transmembrane protein, the mechanism by which these auto-Abs induces apoptosis is unclear. EC membrane proteins were analyzed using bidimensional electrophoresis and Far Western blot, and the HSP60 receptor was identified by mass spectrometry. Heat stress-dependent synthesis of HSP60 and receptor was examined by semiquantitative RT-PCR, and expression was examined by flow cytometry and indirect immunofluorescence. Interaction was demonstrated by coimmunoprecipitations. Lipid rafts were purified to evaluate specific localization, and the apoptotic response was investigated by blocking monoclonal Ab. Mitochondrial HSP70 (mtHSP70) was identified as an HSP60 receptor. Stress was required for ECs to up-regulate mRNA and express mtHSP70 on their surface. HSP60 and mtHSP70 colocalized and interacted within lipid rafts. They were associated with chemokine CC motif receptor 5 (CCR5), also induced at the mRNA and protein levels in stressed ECs. CCR5 was involved in the anti-HSP60-triggered apoptosis of ECs. These results provide new insights into the mechanism by which anti-EC auto-Abs from vasculitides induce apoptosis of ECs.

Repopulation of B-lymphocytes with restricted gene expression using haematopoietic stem cells engineered with lentiviral vectors

B-lymphocytes play a key role in the pathogenesis of many immune-mediated diseases, such as autoimmune and atopic diseases. Therefore, targeting B-lymphocytes provides a rationale for refining strategies to treat such diseases for long-term clinical benefits and minimal side effects. In this study we describe a protocol for repopulating irradiated mice with B-lymphocytes engineered for restricted expression of transgenes using haematopoietic stem cells. A self-inactivating lentiviral vector, which encodes enhanced green fluorescence protein (EGFP) from the spleen focus-forming virus (SFFV) promoter, was used to generate new vectors that permit restricted EGFP expression in B-lymphocytes. To achieve this, the SFFV promoter was replaced with the B-lymphocyte-restricted CD19 promoter. Further, an immunoglobulin heavy chain enhancer (Emu) flanked by the associated matrix attachment regions (MARs) was inserted upstream of the CD19 promoter. Incorporation of the Emu-MAR elements upstream of the CD19 promoter resulted in enhanced, stable and selective transgene expression in human and murine B-cell lines. In addition, this modification permitted enhanced selective EGFP expression in B-lymphocytes in vivo in irradiated mice repopulated with transduced bone marrow haematopoietic stem cells (BMHSCs). The study provides evidence for the feasibility of targeting B-lymphocytes for therapeutic restoration of normal B-lymphocyte functions in patients with B-cell-related diseases.

Altered lipid raft-associated proximal signaling and translocation of CD45 tyrosine phosphatase in B lymphocytes from patients with systemic lupus erythematosus

OBJECTIVE

B lymphocytes from patients with systemic lupus erythematosus (SLE) exhibit defective intracellular signaling, hyperactivity, and autoantibody production. Recent evidence indicates a reduced expression of Lyn kinase, a negative regulator of B cell signaling, and reduced translocation of Lyn into membrane signaling domains in SLE. The present study was undertaken to investigate the causes of this altered regulation of Lyn by assessing the expression levels of regulatory molecules and their translocation into the signaling domains of SLE B lymphocytes.

METHODS

Blood was obtained from 48 patients with SLE and 28 healthy controls for the assessment of B lymphocytes. Levels and intracellular distribution of Lyn, CD45, COOH-terminal Src kinase (Csk), and c-Cbl were studied by Western blotting, confocal microscopy, and flow cytometry. The kinetics of signaling molecule translocation to the B cell receptor (BCR)-antigen synapse were investigated by confocal microscopy.

RESULTS

A profound alteration in the expression and translocation of regulatory signaling molecules in membrane domains of B cells from patients with SLE was observed. B lymphocytes from SLE patients, but not those from healthy controls, expressed a low molecular weight isoform of CD45 in lipid raft signaling microdomains. Kinetic studies revealed that translocation of Lyn, CD45, Csk, and c-Cbl led to increased recruitment and retention of Lyn and CD45 in the BCR-antigen synapse in SLE B cells.

CONCLUSION

The results provide evidence of altered expression and translocation/interaction of kinases and phosphatases in membrane signaling microdomains of B cells from patients with SLE. Altered translocation of CD45 correlated with reduced expression of Lyn, indicating that Lyn is a key molecule in the regulation of BCR-mediated signaling.

An alternative exon 1 of the CD5 gene regulates CD5 expression in human B lymphocytes

T lymphocytes and a subpopulation of B lymphocytes express the CD5 coreceptor. Its functional importance is evident from the multiple levels and developmental stages of the regulation of its expression. We here report the discovery of a novel regulatory exon upstream of the noncoding region of the CD5 gene in humans. This alternate exon 1 is designated E1B (with the conventional exon 1 renamed E1A) and was shown to regulate the expression of CD5. E1B-containing transcripts existed exclusively in B lymphocytes and encoded a protein that was truncated and retained intracellularly. As a consequence, the amount of E1A-containing transcripts was down-regulated and the membrane CD5 expression was diminished in the presence of E1B-containing transcripts. High levels of E1A transcripts were found in chronic lymphocytic leukemia, and there were no E1A transcripts in 697 pre-B cells, which have no membrane CD5. Introduction of E1B into Jurkat cells reduced their membrane expression of CD5, and sequence analysis revealed that the E1B motif is a defective human endogenous retrovirus. A balance between the 2 alternative exons 1 might be central to the regulation of membrane CD5 in human B cells, and, through CD5-associated SH2-containing phosphatase 1, to the modulation of B-cell antigen receptor-transduced signals.

Decreased Lyn expression and translocation to lipid raft signaling domains in B lymphocytes from patients with systemic lupus erythematosus

OBJECTIVE

B lymphocytes from patients with systemic lupus erythematosus (SLE) are hyperactive and produce anti-double-stranded DNA (anti-dsDNA) autoantibodies. The cause or causes of B cell defects in SLE are unknown. In this study, we determined the level and subcellular distribution of Lyn protein, a key negative regulator of B cell receptor signaling, and assessed whether altered Lyn expression is characteristic of B cells in the setting of SLE.

METHODS

Negative selection was used to isolate B lymphocytes from blood. Lipid raft signaling domains were purified from B cells obtained from 62 patients with SLE, 15 patients with rheumatoid arthritis, and 31 healthy controls, by gradient ultracentrifugation. The total Lyn protein level was determined by Western blotting, confocal microscopy, and fluorescein-activated cell sorting (FACS). The distribution of Lyn into lipid raft and nonlipid raft domains was determined by Western blotting and confocal microscopy. Lyn content in B cell subpopulations was determined by FACS. In order to assess B lymphocyte activity, we used (3)H-thymidine incorporation and enzyme-linked immunosorbent assay to measure spontaneous proliferation and IgG and cytokine production by B cells.

RESULTS

This study revealed that B lymphocytes from a majority of patients with SLE have a reduced level of Lyn and manifest altered translocation to lipid rafts. An investigation into the mechanisms of Lyn reduction suggested that increased ubiquitination is involved. This was evident from increased ubiquitination of Lyn and translocation of c-Cbl into lipid rafts. Studies of B cell responses showed that altered Lyn expression was associated with heightened spontaneous proliferation, anti-dsDNA autoantibodies, and increased interleukin-10 production.

CONCLUSION

This study provides evidence for altered Lyn expression in B cells from a majority of patients with SLE. Altered Lyn expression in SLE may influence the B cell receptor signaling and B cell hyperactivity that are characteristic of the disease.

Altered lipid raft-associated signaling and ganglioside expression in T lymphocytes from patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is characterized by abnormalities in T lymphocyte receptor-mediated signal transduction pathways. Our previous studies have established that lymphocyte-specific protein tyrosine kinase (LCK) is reduced in T lymphocytes from patients with SLE and that this reduction is associated with disease activity and parallels an increase in LCK ubiquitination independent of T cell activation. This study investigated the expression of molecules that regulate LCK homeostasis, such as CD45, C-terminal Src kinase (CSK), and c-Cbl, in lipid raft domains from SLE T cells and investigated the localization of these proteins during T cell receptor (TCR) triggering. Our results indicate that the expression of raft-associated ganglioside, GM1, is increased in T cells from SLE patients and LCK may be differentially regulated due to an alteration in the association of CD45 with lipid raft domains. CD45 tyrosine phosphatase, which regulates LCK activity, was differentially expressed and its localization into lipid rafts was increased in T cells from patients with SLE. Furthermore, T cells allowed to "rest" in vitro showed a reversal of the changes in LCK, CD45, and GM1 expression. The results also revealed that alterations in the level of GM1 expression and lipid raft occupancy cannot be induced by serum factors from patients with SLE but indicated that cell-cell contact, activating aberrant proximal signaling pathways, may be important in influencing abnormalities in T cell signaling and, therefore, function in patients with SLE.

The role of antigen in the selection of the human V3-23 immunoglobulin heavy chain variable region gene

The immune system mounts antibody responses using few of the available immunoglobulin variable region (IgV) genes with some, such as the V3-23 heavy chain gene, regularly over-represented in responses to many antigens. The reasons for the over-representation of some V genes have not been established; the process could be either stochastic or selective. We demonstrated previously that the V3-23 gene, which is over-represented in the primary B lymphocyte repertoire in humans, encodes antibodies with differing antigen-binding reactivities in transgenic mice that express the human V3-23 gene. The aim of the current study was to assess if V3-23 gene over-representation is stochastic or could be influenced by antigen exposure. Transgenic mice were immunized with human IgG-Fc (hIgG-Fc), bovine collagen type II (bCII) or tetanus toxoid (TT), and hybridomas secreting human mu chain-containing antibodies generated. These were tested for binding to the immunogens and a panel of self- and exogenous antigens. In hybridomas derived from hIgG-Fc-immunized mice, 53% secreted antibodies specific for hIgG-Fc. A similar proportion (54%) of hybridomas from bCII-immunized mice secreted antibody that bound to collagen. By contrast, only 21% of hybridomas from mice immunized with TT bound to tetanus toxoid. Intriguingly, chimaeric antibodies generated from mice immunized with bCII or TT were mainly polyreactive, similar to antibodies generated from naive transgenic mice. However, hybridomas generated from mice immunized with hIgG-Fc were mainly specific, reacting exclusively with hIgG-Fc. These results suggest that selection and eventual expansion of B lymphocytes expressing the V3-23 gene are likely to be determined by exposure to self- and/or environmental antigens.

Cross-reactivity and pathogenicity of anti-DNA autoantibodies in systemic lupus erythematosus

Autoantibodies to DNA were discovered over 40 years ago following the discovery a few years earlier of the 'LE' cell phenomenon by Hargraves and colleagues in 1948. These investigators noted that, when leucocytes were incubated with serum from lupus patients, changes in the nucleus could be seen together with phagocytosis of nuclear remnants by polymorphonuclear leucocytes. Since that time numerous studies in many laboratories have investigated almost every aspect of anti-DNA antibodies, partly to identify what determines their pathology. Whilst a subset of anti-DNA antibodies, especially anti-native, or double-stranded DNA (dsDNA) antibodies constitutes a hallmark of lupus disease and a diagnostic criterion, it is now clear that not all anti-DNA autoantibodies are of pathogenic relevance. Moreover, anti-DNA autoantibodies may also be found in other connective tissue disorders. Here we briefly review studies presented at the fifth international workshop on anti-DNA autoantibodies held in London to highlight relevant properties of pathogenic anti-DNA antibodies.

Tumour necrosis factor alpha in systemic lupus erythematosus and anti-DNA autoantibody production

Tumour necrosis factor (TNFalpha) is a cytokine with a wide range of diverse and at times paradoxical effects. These include immunoregulatory, lymphoid organogenesis and pro-inflammatory effects. In recent years, TNFalpha has become a focus of interest more for its inflammatory effects in a number of chronic autoimmune diseases. This interest culminated in the successful treatment of patients with rheumatoid arthritis, Crohn's diseases and ankylosing spondylitis with blocking antibodies or soluble TNFalpha receptors. Paradoxically, however, TNFalpha also has immunomodulatory effects in some autoimmune conditions such as lupus in some mouse models of the disease and in diabetes in the none-obese diabetic mouse. The role TNFalpha plays in human systemic lupus erythematosus is, however, controversial. In this article we review some of the studies carried out to elucidate the effects of TNFalpha in lupus disease and likely mechanisms of action. Further, we discuss recent data on the likely effects of blocking TNFalpha on anti-DNA autoantibody production.

Immunopathology and the gene therapy of lupus

Lupus is a chronic autoimmune inflammatory disease with complex clinical manifestations. In humans, lupus, also known as systemic lupus erythematosus (SLE), affects between 40 and 250 individuals, mostly females, in each 100 000 of the population. There are also a number of murine models of lupus widely used in studies of the genetics, immunopathology, and treatment of lupus. Human patients and murine models of lupus manifest a wide range of immunological abnormalities. The most pervasive of these are: (1) the ability to produce pathogenic autoantibodies; (2) lack of T- and B-lymphocyte regulation; and (3) defective clearance of autoantigens and immune complexes. This article briefly reviews immunological abnormalities and disease mechanisms characteristic of lupus autoimmunity and highlight recent studies on the use of gene therapy to target these abnormalities.

Increased ubiquitination and reduced expression of LCK in T lymphocytes from patients with systemic lupus erythematosus

OBJECTIVE

To explore regulation of proximal signaling and composition of lipid rafts in T lymphocytes from patients with systemic lupus erythematosus (SLE).

METHODS

The expression, phosphorylation, and degradation of lipid raft-associated signaling molecules in T lymphocytes from 50 patients with SLE compared with 28 healthy controls and 22 rheumatoid arthritis patients were investigated. Lipid raft and nonraft fractions from T cells were isolated by ultracentrifugation. Proteins in the lipid raft and nonraft fractions were analyzed by Western blotting and probed for phosphotyrosine activity and for LCK, LAT, and CD3 epsilon. Immunoprecipitation experiments were performed to assess protein ubiquitination in T cell lysates. T cell phenotype and levels of intracellular LCK were determined by flow cytometry.

RESULTS

LCK, an essential signaling molecule for T cell activation, was significantly reduced in both lipid raft and nonraft fractions of T lymphocytes from patients with active SLE compared with controls, and the reduction was independent of treatment. To identify the likely causes of reduced LCK, we explored the possibility that chronic activation of T lymphocytes underlies LCK degradation. The results revealed an increase in protein ubiquitination, and specifically LCK ubiquitination, in T cells from SLE patients. However, our findings suggest that the increase in ubiquitination is independent of T cell activation.

CONCLUSION

LCK is reduced in T cell lipid rafts from patients with SLE. This reduction appears to be independent of activation and may be associated with abnormal ubiquitin-mediated regulation mechanisms.

Polymorphism in the immunoglobulin VH gene V1-69 affects susceptibility to rheumatoid arthritis in subjects lacking the HLA-DRB1 shared epitope

OBJECTIVE

To investigate the contribution of polymorphism in the immunoglobulin heavy chain variable region V1-69 gene set to genetic susceptibility to rheumatoid arthritis (RA) in Czech and British patients.

METHODS

We used V1-69 gene sequence-specific polymerase chain reaction (PCR) and restriction enzyme digestion to study polymorphism in the V1-69 gene set in germline DNA of 109 Czech and 159 British RA patients and 164 ethnically matched controls. Polymorphism was further studied by nucleotide sequencing of the V1-69 gene locus in germline DNA.

RESULTS

We found that all patients and controls had at least one V1-69 gene copy. In the Czech RA cohort, the dimorphic nucleotide in codon 73 of V1-69 (GAA or AAA) was present in the homozygous form 73(A/A) in 31 of 109 (28.4%) RA patients vs 12 of 79 (15.2%) controls [odds ratio (OR)=2.22, P<0.001]. When the RA patients and controls were classified according to HLA shared epitope (SE) status, 73(A/A) was found in 18 of 76 (23.7%) SE(+) patients compared with 13 of 38 (34.2%) SE(-) patients, four of 12 (18.2) SE(+) controls and eight of 57 (14%) SE(-) controls. This suggests that homozygosity for the dimorphic sequence 73(A) contributed to susceptibility to RA in SE(-) Czech individuals (OR=3.2, P<0.001). The most striking observation was that none of the 38 SE(-) Czech patients, compared with 11 of 76 (14.5%) SE(+) RA patients, three of 22 (13.6%) SE(+) and 11 of 57 (19.3%) SE(-) ethnically matched controls, were homozygous for the alternative dimorphic sequence 73(G/G) (OR=9.1, P<0.05). These data, however, were not replicated in a Caucasoid British RA population.

CONCLUSION

The dimorphic sequence at codon 73 (73(A/A)) of the V1-69 gene contributes to genetic susceptibility in SE(-) Czech RA patients.

The effects of a human IgM monoclonal anticardiolipin antibody on pregnancy in a transgenic mouse model

The clinical features of antiphospholipid (or Hughes') syndrome (APS) are most commonly seen in individuals who have raised levels of IgG anticardiolipin antibodies. Most murine models of the syndrome have involved the administration of such antibodies to normal mice. However, APS can occur in the presence of raised levels of serum IgM anticardiolipin antibodies alone. The present study was designed to see if an IgM monoclonal antibody can induce changes in mice similar to those seen in human APS. This antibody, BH1, has previously been derived from a patient with primary APS. In its ligand-binding and idiotypic characteristics it is representative of antiphospholipid antibodies (aPL) found in the serum of patients with APS. In order to minimise the immune response to human IgM, we used transgenic mice (F15) which express, and are predicted to be tolerant of, human immunoglobulin mu chains. The features of APS may develop more readily in individuals who have an existing autoimmune disorder, such as systemic lupus erythematosus (SLE). We therefore crossed these transgenic mice with New Zealand Black (NZB, SLE-prone) mice, and used the progeny (F15 x NZB/F1) in our experiments. Twenty-four F15 x NZB/F1 mice were given BH1, or a control IgM antibody, (A5566) immediately preceding and then three times during pregnancy. There was a reduction in the mean number of foetuses in animals given BH1 compared with those given A5566 (8.6 vs 11.0; P < 0.05), and a similar reduction in mean total foetal weight per pregnancy (9.05 vs 12.73 g; P < 0.05). Two mice showed a marked reduction in platelet count. No evidence of thrombosis was detected macroscopically or histologically. Our results show a lower incidence of APS-type features compared to previous studies in which mice have been administered aPL. This may be because BH1 is an IgM antibody. Nevertheless, the data support the concept that IgM aPL of particular ligand-binding specificities may have a direct pathogenetic role in certain cases of human APS.

Higher frequency of allele 2 of the interleukin-1 receptor antagonist gene in patients with juvenile idiopathic arthritis

OBJECTIVE

An increased incidence of allele 2 of the interleukin-1 receptor antagonist gene (IL1RN*2) in several inflammatory diseases has recently been reported. The aim of this study was to examine a variable number tandem repeat (VNTR) polymorphism of the IL1RN gene in patients with juvenile idiopathic arthritis (JIA).

METHODS

Findings in 185 Czech patients with JIA were compared with those in 168 Czech controls, 50 JIA patients and 52 controls of Turkish origin, and 79 controls from central England. VNTR polymorphism analysis of IL1RN was performed by polymerase chain reaction using 2 flanking primers to amplify an 86-bp tandem repeat region in intron 2.

RESULTS

The frequency and carriage rate of IL1RN*2 were significantly increased in Czech JIA patients compared with the Czech controls (frequency 27.6% versus 15.8%; carriage rate 44.3% versus 26.2%). Increased frequency and carriage rate of IL1RN*2 were found in 23.3% and 40.0% of Turkish JIA patients and in 17.3% and 34.6% of ethnically matched controls. The high representation of IL1RN*2 in 52.3% of the 22 patients with extended oligoarthritis, 31.3% of the 56 patients with enthesitis-related arthritis, and 42.9% of the 14 patients with other arthritis was particularly responsible for the increased frequency of IL1RN*2 in the Czech JIA patients. We found no association of IL1RN*2 with disease activity or severity parameters.

CONCLUSION

Inheritance of IL1RN*2 may contribute to genetic susceptibility in several forms of autoimmune diseases, including JIA. The IL1RN*2 allele may be useful as a prognostic indicator of the evolution of an extended oligoarticular course of JIA.

Analysis of the expressed immunoglobulin variable region heavy chain gene products in paraproteins from Iranian patients with multiple myeloma

The frequency of expression of immunoglobulin (Ig) variable region heavy (VH ) chain gene products was studied in 43 Iranian patients with mutiple myeloma (MM). The expressed VH gene families and associated cross-reactive idiotypes (CRI) were analysed by immunoblotting and ELISA, using peptide-induced polyclonal antibodies specific for VH 1-VH 6 gene families and monoclonal antibodies (MAb) recognising CRI linked to theVH 1, VH 3, VH 4 and VH 6 gene families. The results revealed that the VH 3 family (60. 5%) was the most predominant gene family. In contrast, no paraproteins were encoded by genes from the VH 2 gene family and only 2.3% were encoded by the VH 5 family. The panel of paraproteins tested rarely expressed the probed VH -associated CRI. Our results suggest that: 1-The Ig VH genes, may not be randomly expressed in the malignant plasma cells from Iranian patients with MM. 2- Some of the genes seem to be negatively selected or highly mutated, as evidenced by the lack of expression of the probed CRI.

Rearrangement of the human heavy chain variable region gene V3-23 in transgenic mice generates antibodies reactive with a range of antigens on the basis of VHCDR3 and residues intrinsic to the heavy chain variable region

To formulate a 'logic' for how a single immunoglobulin variable region gene generates antibodies with different antigen specificity and polyreactivity, we analysed chimeric antibodies produced in transgenic mice carrying the germ-line human V3-23 gene, multiple diversity (D) and joining (J) gene segments. Hybridomas producing antibodies encoded by the V3-23 gene in combination with different mouse Vkappa genes were obtained by fusion of splenocytes from transgenic mice. All antibodies had human mu-chains and mouse light chains, were multimeric in structure and expressed the human V3-23 gene. Nucleotide sequence analyses of genes encoding the heavy and light chains of 12 antibodies in relation to antigen specificity highlighted the importance of heavy chain variable region CDR3 in determining reactivity with different antigens. However, the results also suggest that non-CDR3 sequences intrinsic to the V3-23 gene itself may be involved in, or determine, the binding of the chimeric antibodies to some of the antigens tested in the current study.

Molecular analysis of human immunoglobulin heavy chain variable region associated determinants recognized by anti-VH3 antibodies 7B4, B6 and D12

7B4, B6 and D12 are murine monoclonal antibodies (MoAb) that bind to some human immunoglobulin heavy chain products of the closely related V3-30, V3-30.3 and V3-33 genes from the VH3 family. B6 and D12 have additional reactivities with some immunoglobulins (Ig) encoded by the V3-11 and V3-7 genes; D12 also reacts with some V3-43 gene Ig. We show here, by site-directed mutagensis, that the lysine at position 57 in the complementarity-determining region 2 (CDR-2) of the V3-30 gene product is crucial for epitope recognition by all three anti-VH3 MoAbs. Further analysis of the amino-acid sequences of a large panel of Ig reactive, or nonreactive, with MoAb 7B4 indicates that the determinant recognized by 7B4 is dependent on the presence of the tetrapeptide sequence NKYY between positions 56 and 59 in the CDR-2. Comparing the efficiency of 7B4 reactivity with VH3 gene-encoded human Ig indicates that amino-acid position 4 in the frame region 1 (FR-1) may also influence the binding of 7B4 to Ig encoded by three very closely related germline genes, V3-30, V3-30.3 and V3-33. NKYY is also found on the gp120 V3 region of human immunodeficiency virus (HIV)-2, SIV and HTLV-4. We also report that other tetrapeptide sequences found on the 56-59 motif of heavy chain variable regions encoded by germline genes are expressed on the solvent exposed V2 region of gp120 of HIV-1 isolates. The possible significance of these observations is discussed.

CD4+ T lymphocytes with constitutive CD40 ligand in preautoimmune (NZB x NZW)F1 lupus-prone mice: phenotype and possible role in autoreactivity

Lupus disease is marked by B lymphocyte hyperactivity and the production of Abs to dsDNA. The production of these anti-dsDNA Abs is T lymphocyte dependent. However, it is not clear how CD4+ T lymphocytes provide help for B lymphocytes to produce IgG anti-dsDNA Abs. One possible mechanism is suggested by studies showing that human patients with systemic lupus erythematosus and lupus mice have increased numbers of CD40 ligand (CD40L)+ T and B lymphocytes. The results described in this study reveal that young, clinically healthy lupus-prone New Zealand Black x New Zealand White F1 (BWF1) mice have naive CD4+ T cells with preformed CD40L. These cells contribute to a brisk response to immunization and to the production of anti-dsDNA Abs. In vitro experiments revealed that CD4+ T cells with preformed CD40L could, upon stimulation, provide antiapoptotic signals for B cells but could not induce proliferation or reduce activation threshold. These results suggest that the direct target cells for the effect of T cells with preformed CD40L in lupus may not be B lymphocytes.

Immuno- and genetic therapy in autoimmune diseases

Animal models of autoimmune disease have been developed that mimic some aspects of the pathophysiology of human disease. These models have increased our understanding of possible mechanisms of pathogenesis at the molecular and cellular level and have been important in the testing, development and validation of new immunotherapies. The susceptibility to develop disease in the majority of these models is polygenic as is the case in humans. The exceptions to this rule are gene knock outs and transgenic models of particular genes which, in particular genetic backgrounds, have also contributed to the understanding of single gene function and their possible contribution to pathogenesis. Gene therapy approaches that target immune functions are being developed with encouraging results, despite the polygenic nature of these diseases. Basically this novel immuno-genetic therapy harnesses the knowledge of immunology with the myriad of biotechnological breakthroughs in vector design and delivery. Autoimmune disease is the result of genetic dysregulation which could be controlled by gene therapy. Here we summarize the genetic basis of these human diseases as well as some of the best characterized murine models. We discuss the strategies for their treatment using immuno- and gene therapy.

Increased IgA rheumatoid factor and V(H)1 associated cross reactive idiotype expression in patients with Lyme arthritis and neuroborreliosis

OBJECTIVE

To investigate whether autoreactive mechanisms occur in Lyme disease (LD) by determining IgA, IgG and IgM rheumatoid factor (RF) concentrations and RF associated cross reactive idiotype (CRI) expression in the serum of LD patients, with comparison to patients with rheumatoid arthritis (RA).

METHODS

The RF isotype profiles were determined in 59 patients with LD; erythema migrans (EM) (n=19), neuroborreliosis (NB) (n=20) and Lyme arthritis (LA) (n=20). Mouse monoclonal antibodies (mAbs) G6 and G8 (V(H)1 gene associated), D12 (V(H)3 gene associated) and C7 (V(kappa)III gene associated) were then used to determine the RF associated CRI expression on IgM antibodies in 16 of these LD patients (eight seropositive for RF); (EM (n=3), NB (n=6), LA (n=7)).

RESULTS

Seven (18%) patients with either NB or LA had increased concentrations of IgA RF compared with none with EM. Significant differences in the number of patients with raised concentrations of IgG RF or IgM RF were not found between the LD patient groups. Five (3NB, 1LA and 1 EM) (31%) and three (2NB and 1LA) (19%) of LD patients had raised concentrations of the CRIs recognised by mAbs G6 and G8, respectively. These CRIs were detected in LD sera both with and without raised concentrations of RF and were not demonstrated on anti-Borrelia burgdorferi antibodies using ELISA. No LD sera tested had raised concentrations of the determinants recognised by mAbs C7 or D12.

CONCLUSION

Significantly raised concentrations of IgA RF and increased use of V(H)1 germline gene associated CRIs are found on IgM antibodies in the serum of LD patients. These data indicate the recruitment of autoreactive B lymphocytes in some patients with the later stages of LD.

Rheumatoid factor isotype switch and somatic mutation variants within rheumatoid arthritis synovium

The presence of clonally-related B-lymphocyte aggregates within synovial lining tisue of rheumatoid arthritis (RA) patients suggests a germinal centre-like reaction, which may hold implications for disease pathogenesis and the causes of chronic inflammation. We studied 250 rheumatoid factor (RF) heavy-chain sequences cloned from the synovium of three patients with RA, to determine whether they undergo both somatic mutation and isotype switching consistent with this hypothesis. Size analysis of immunoglobulin heavy-chain cDNAs from synovial RF+ B cells revealed oligoclonal RF+ populations and identically-sized VH-D-JH transcripts of different immunoglobulin isotypes. Sequencing of individual inserts selected from cloned immunoglobulin heavy-chain cDNAs demonstrated a clonal relationship between immunoglobulin M (IgM) RF and IgA RF, suggesting that this isotype switch occurred in synovium. Furthermore, most somatic mutations were found to have occurred after this isotype switch. This finding suggests that the RA synovial microenvironment sustains somatic mutation and isotype switching in RF-specific B lymphocytes akin to secondary lymphoid organs.

Molecular characterization of the VH1-specific variable region determinants recognized by anti-idiotypic monoclonal antibodies G6 and G8

Mutational analysis was used to determine the structural basis for the binding of the murine anti-idiotypic (anti-Id) monoclonal antibodies (MoAb) G6 and G8 to VH1-encoded antibodies. The MoAb G6 binds a cross-reactive idiotope present on the heavy (H) chains of immunoglobulins (Ig) encoded by 51p1-related gene segments, but not those encoded by hv1263-related gene segments. Gene segments 51p1 (DP-10) and hv1263 differ by only four amino acids; three in complementarity-determining region 2 (CDR2), and one in framework region 3 (FR3). The MoAb G8 also binds 51p1-related sequences, although it is undetermined whether G8 can bind hv1263-related sequences. In order to localise the Ids recognized by MoAbs G6 and G8 on 51p1-encoded antibodies, recombinant antibodies containing H-chain mutants were expressed in insect cells. Idiotypic analysis on the expressed recombinant proteins definitively localised the reactivity in each molecule. These studies should be important in the structural appreciation for critical serological reagents.

The BH1 idiotype defines a population of anticardiolipin antibodies closely associated with the antiphospholipid syndrome

BACKGROUND

A human IgM monoclonal anticardiolipin antibody - BH1 - has previously been described, which has characteristics typical of antiphospholipid antibodies in the serum of patients with antiphospholipid syndrome (APS). It appears to be idiotypically distinct from other human monoclonal autoantibodies of different or overlapping ligand-binding specificities derived from patients with related conditions.

AIM

To determine whether the idiotype of BH1 is expressed on particular populations of antibodies (antiphospholipid and anti-beta2-glucoprotein I) in the serum of patients with APS and other conditions.

METHODS

Sera from patients with APS (9), systemic lupus erythematosus without APS ('uncomplicated SLE' -9), and rheumatoid arthritis (RA 15), and from normal controls (15) were tested by enzyme-linked immunosorbent assay (ELISA) for reactivity with cardiolipin, beta2 glycoprotein I (beta2GPI), and a polyclonal anti-idiotype raised against BH1 (RIdBH1). Absorption experiments were subsequently performed on selected sera using micelles of cardiolipin or phosphatidyl choline.

RESULTS

Eight out of nine patients with APS were positive for binding to RIdBH1 (IgG and/or IgM), while only one patient with uncomplicated SLE and none of the patients with RA or the healthy controls were positive. Although all of the patients with APS were positive for binding to beta2GPI, there was poor correlation between these results and levels of binding to cardiolipin and RIdBH1. Absorption of sera from patients with APS by cardolipin micelles resulted in a median reduction in IgG anticardiolipin and anti-beta2GPI activity of 81.6% and 6.3% respectively. For those sera positive for IgG reactivity with RIdBH1 the median reduction in this activity was 79.4%. Antibodies eluted from selected micelles showed activity against cardiolipin, beta2GPI and RIdBH1. Three anticardiolipin-positive sera from patients with RA were similarly absorbed; however the eluted antibodies failed to bind to RIdBH1. Absorption of all these sera with phosphatidyl choline resulted in no significant reduction in any of these activities.

CONCLUSIONS

The BH1 idiotype defines a population of serum antibodies associated with features of APS. The antibody response in this condition, though diverse, may include the expression of a restricted group of variable region genes.