Objective

Triptolide and tripdiolide are thought to be active components of the Chinese antirheumatic herbal remedy Tripterygium wilfordii Hook F, which has been shown to be effective in treating murine lupus nephritis. This study was undertaken to examine the therapeutic effect of triptolide and tripdiolide on established lupus nephritis in (NZB X NZW)F1 mice.

Methods

(NZB X NZW)F1 mice were treated with vehicle, triptolide, or tripdiolide for 15 weeks beginning at the age of 29 weeks (after the development of lupus nephritis). Body weight, proteinuria, and anti-doublestranded DNA (anti-dsDNA) antibodies were monitored, and the kidney and spleen were assessed histologically. Culture supernatants of spleen mononuclear cells were assayed for cytokines.

Results

By 28 weeks, most (NZB X NZW)F1 mice had developed lupus nephritis. Vehicle-treated mice exhibited progressive proteinuria, hypoalbuminemia, elevated blood urea nitrogen (BUN) levels, and evidence of severe nephritis. In contrast, proteinuria and BUN levels were significantly reduced in mice treated with either triptolide or tripdiolide as compared with those treated with vehicle. There was no hypoalbuminemia or apparent evidence of lupus nephritis in mice treated with either of the 2 diterpenoids. At 44 weeks of age, the survival rate in mice treated with vehicle (35.7%) was markedly lower than that in mice treated with either triptolide (87.5%) or tripdiolide (88.2%). The mean level of anti-dsDNA antibody in mice treated with tripdiolide was lower than that in the vehicle-treated mice upon completion of the treatment course. Production of tumor necrosis factor, interleukin-6, and monocyte chemoattractant protein 1 by spleen cells was also decreased after diterpenoid therapy.

Conclusion

Therapy with triptolide or tripdiolide significantly ameliorated lupus nephritis in (NZB X NZW)F1 mice, reduced cytokine and chemokine production, and prolonged survival.

Systemic lupus erythematosus (SLE) is a generalized autoimmune disease characterized by abnormal B cell activation and the occurrence of increased frequencies of circulating plasma cells (PC). The molecular characteristics and nature of circulating PC and B cells in SLE have not been completely characterized. Microarray analysis of gene expression was used to characterize circulating PC in subjects with active SLE. Flow cytometry was used to sort PC and comparator B cell populations from active SLE blood, normal blood and normal tonsil. The gene expression profiles of the sorted B cell populations were then compared.

SLE PC exhibited a similar gene expression signature as tonsil PC. The differences in gene expression between SLE PC and normal tonsil PC and tonsil plasmablasts (PB) suggest a mature Ig secreting cell phenotype in the former population. Despite this, SLE PC differed in expression of about half the genes from previously published gene expression profiles of normal bone marrow PC, indicating that these cells had not achieved a fully mature status. Abnormal expression of several genes, including CXCR4 and S1P1, suggests a mechanism for the persistence of SLE PC in the circulation. All SLE B cell populations revealed an interferon (IFN) gene signature previously only reported in unseparated SLE peripheral blood mononuclear cells. These data indicate that SLE PC are a unique population of Ig secreting cells with a gene expression profile indicative of a mature, but not fully differentiated phenotype.

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that is known to be associated with polyclonal B-cell hyperreactivity. The underlying causes of the diffuse B-cell over-reactivity are unclear, but potential candidates include (a) intrinsic hyper-reactivity leading to polyclonal B-cell activation with disturbed activation thresholds and ineffective negative selection; (b) lack of immunoregulatory functions; (c) secondary effects of an overactive inflammatory environment, such as overactive germinal center and ectopic follicular activity; and/or (d) disturbed cytokine production by non-B immune cells. These mechanisms are not mutually exclusive and may operate to varying extents and at varying times in SLE. Phenotypic and molecular studies as well as the results of recent clinical trials have begun to provide new insights to address these possibilities. Of importance, new information has made it possible to distinguish between the contribution played by abnormalities in central checkpoints that could lead to a pre-immune repertoire enriched in autoreactive B cells, on the one hand, and the possibility that autoimmunity arises in the periphery from somatic hypermutation and abnormal selection during T cell-dependent B-cell responses on the other. There is an intriguing possibility that apoptotic material bound to the surface of follicular dendritic cells positively selects autoreactive B cells that arise from non-autoreactive B-cell precursors as a result of somatic hypermutation and thereby promotes the peripheral emergence of autoimmunity.

The Second Kitasato Symposium: New Prospects for Cytokines brought together researchers and rheumatologists to consider the essential role of cytokines in health and their contributions to autoimmunity. Topics addressed during the Symposium - which was held in Berlin, Germany from 27 to 29 May 2010 - included established and new cytokine targets in arthritis and autoimmunity and innovative aspects of osteoimmunology as well as current perspectives from translational and clinical studies. The keynote lecture, delivered by George Kollias, focused on insights gained from animal models into the mechanisms of TNF function in chronic inflammation and autoimmunity. The presentations at the Symposium resulted in productive discussions regarding potential new targets for the treatment of rheumatoid arthritis and other autoimmune disorders.

Background

Antibodies (Abs) produced during HIV-1 infection rarely neutralize a broad range of viral isolates; only eight broadly-neutralizing (bNt) monoclonal (M)Abs have been isolated. Yet, to be effective, an HIV-1 vaccine may have to elicit the essential features of these MAbs. The V genes of all of these bNt MAbs are highly somatically mutated, and the VH genes of five of them encode a long (≥20 aa) third complementarity-determining region (CDR-H3). This led us to question whether long CDR-H3s and high levels of somatic mutation (SM) are a preferred feature of anti-HIV bNt MAbs, or if other adaptive immune responses elicit them in general.

Methodology and Principal Findings

We assembled a VH-gene sequence database from over 700 human MAbs of known antigen specificity isolated from chronic (viral) infections (ChI), acute (bacterial and viral) infections (AcI), and systemic autoimmune diseases (SAD), and compared their CDR-H3 length, number of SMs and germline VH-gene usage. We found that anti-HIV Abs, regardless of their neutralization breadth, tended to have long CDR-H3s and high numbers of SMs. However, these features were also common among Abs associated with other chronic viral infections. In contrast, Abs from acute viral infections (but not bacterial infections) tended to have relatively short CDR-H3s and a low number of SMs, whereas SAD Abs were generally intermediate in CDR-H3 length and number of SMs. Analysis of VH gene usage showed that ChI Abs also tended to favor distal germline VH-genes (particularly VH1-69), especially in Abs bearing long CDR-H3s.

Conclusions and Significance

The striking difference between the Abs produced during chronic vs. acute viral infection suggests that Abs bearing long CDR-H3s, high levels of SM and VH1-69 gene usage may be preferentially selected during persistent infection.

Objective

To assess the safety of interleukin-6 receptor inhibition and to collect preliminary data on clinical and immunologic efficacy of tocilizumab in patients with systemic lupus erythematosus (SLE).

Methods

In an open label, dose-escalating, Phase I study, 16 patients with mild to moderate disease activity were treated bi-weekly for 12 weeks with one of three doses (2 mg/kg [n=4], 4 mg/kg [n=6], 8 mg/kg [n=6]) of tocilizumab and followed for 8 additional weeks.

Results

The infusions were well tolerated. Tocilizumab led to dose-related decreases in absolute neutrophil count with a median decrease of 38% in the 4 mg/kg and 56% in the 8 mg/kg dose groups. Neutrophil counts returned to normal after cessation of treatment. One subject was withdrawn because of neutropenia. Infections occurred in 11 patients; none was associated with neutropenia. Disease activity showed a significant improvement with 8/15 evaluable patients having a decrease of 4 or more points in the modified SELENA-SLEDAI score. Arthritis improved in all seven patients with arthritis at baseline and resolved in four. Anti-dsDNA antibody levels decreased by a median 47% in the 4 and 8 mg/kg dose groups compared to a 7.8% decrease in IgG levels. These changes together with a significant decrease in circulating plasma cells suggest a specific effect of tocilizumab on autoantibody producing cells.

Conclusion

Although neutropenia may limit the maximum dose of tocilizumab in SLE, the observed clinical and serological response data are promising and warrant further studies to establish the optimal dosing regimen and efficacy.

Systemic lupus erythematosus (SLE) is a chronic, multisystem autoimmune disease characterized by the differentiation of short- and long-lived immunoglobulin secreting plasma cells that secrete pathogenic autoantibodies. Ectopic germinal centers and plasma cells secreting autoantibodies have been observed in lupus nephritis kidneys. Candidate genetic susceptibility loci for SLE include genes that affect differentiation and survival of plasma cells, such as those that influence activation, proliferation, cytokine and chemokine secretion/responsiveness, and apoptosis of the T and B cells that are involved in humoral immunity generated in germinal centers, as well as genes that are involved in presentation and clearance of apoptotic material and autoantigens by antigen presenting cells and other phagocytes. Emerging data have demonstrated that B lymphocytes are active participants in humoral immune responses that lead to T-dependent and T-independent differentiation of immunoglobulin-secreting plasma cells by homotypic CD154–CD40 interactions as well as continued stimulation by B cell activating factor through B cell maturation antigen, B cell activating factor receptor and transmembrane activater.

Background

Extracts of the medicinal plant Tripterygium wilfordii Hook F (TwHF) have been used in China for centuries to treat a spectrum of inflammatory diseases.

Objective

To compare the benefits and side effects of TwHF extract with those of sulfasalazine for the treatment of active rheumatoid arthritis.

Design

Randomized, controlled trial. A computer-generated code with random, permuted blocks was used to assign treatment.

Setting

2 U.S. academic centers (National Institutes of Health, Bethesda, Maryland, and University of Texas, Dallas, Texas) and 9 rheumatology subspecialty clinics (in Dallas and Austin, Texas; Tampa and Fort Lauderdale, Florida; Arlington, Virginia; Duncanville, Pennsylvania; Wheaton and Greenbelt, Maryland; and Lansing, Michigan).

Patients

121 patients with active rheumatoid arthritis and 6 or more painful and swollen joints.

Intervention

TwHF extract, 60 mg 3 times daily, or sulfasalazine, 1 g twice daily. Patients could continue stable doses of oral prednisone or nonsteroidal anti-inflammatory drugs but had to stop taking disease-modifying antirheumatic drugs at least 28 days before randomization.

Measurements

The primary outcome was the rate of achievement of 20% improvement in the American College of Rheumatology criteria (ACR 20) at 24 weeks. Secondary end points were safety; radiographic scores of joint damage; and serum levels of interleukin-6, cholesterol, cortisol, and adrenocorticotropic hormone.

Results

Outcome data were available for only 62 patients at 24 weeks. In a mixed-model analysis that imputed data for patients who dropped out, 65.0% (95% CI, 51.6% to 76.9%) of the TwHF group and 32.8% (CI, 21.3% to 46.0%) of the sulfasalazine group met the ACR 20 response criteria (P = 0.001). Patients receiving TwHF also had significantly higher response rates for ACR 50 and ACR 70 in mixed-model analyses. Analyses of only completers showed similar significant differences between the treatment groups. Significant improvement was demonstrated in all individual components of the ACR response, including the Health Assessment Questionnaire disability score. Interleukin-6 levels rapidly and significantly decreased in the TwHF group. Although not statistically significant, radiographic progression was lower in the TwHF group. The frequency of adverse events was similar in both groups.

Limitations

Only 62% and 41% of patients continued receiving TwHF extract and sulfasalazine, respectively, during the 24 weeks of the study. Long-term outcome data were not collected on participants who discontinued treatment.

Conclusion

In patients who continued treatment for 24 weeks and could also use stable oral prednisone and nonsteroidal anti-inflammatory drugs, attainment of the ACR 20 response criteria was significantly greater with TwHF extract than with sulfasalazine.

Primary Funding Source

National Institute of Arthritis and Musculoskeletal and Skin Diseases.

B-cell development is tightly regulated, including the induction of B-cell memory and antibody-secreting plasmablasts and plasma cells. In the last decade, we have expanded our understanding of effector functions of B cells as well as their roles in human autoimmune diseases. The current review addresses the role of certain stages of B-cell development as well as plasmablasts/plasma cells in immune regulation under normal and autoimmune conditions with particular emphasis on systemic lupus erythematosus. Based on preclinical and clinical data, B cells have emerged increasingly as both effector cells as well as cells with immunoregulatory potential.

The Kitasato Symposium 2009: New Prospects for Cytokine Inhibition was held in Berlin, Germany from 7 to 9 May 2009. The key aims of this meeting were to bring together a group of front-line researchers and rheumatologists to evaluate the use of cytokine blockade and to examine the role of certain cytokines in the pathogenesis of rheumatoid arthritis and other autoimmune diseases. A keynote lecture delivered by Professor Jean-Michel Dayer provided an up-to-date overview of the interactions occurring between the immune system and acute phase proteins. Other speakers discussed the role of cytokines in rheumatoid arthritis, including their role in joint destruction, as well as their regulatory role upon T cells and B cells. The involvement of cytokines in other autoimmune diseases was also addressed.

VH replacement is a form of IgH chain receptor editing that is believed to be mediated by recombinase cleavage at cryptic recombination signals (cRSS) embedded in IGHV genes. Whereas there are several reports of IGHV replacement in primary and transformed human B cells and murine models, it remains unclear whether IGHV replacement contributes to the normal human B cell repertoire. We identified VH → VHDJH compound rearrangements from fetal liver, fetal bone marrow and naive peripheral blood, all of which involved invading and recipient IGHV4 genes that contain a cryptic heptamer, 13 base pair (bp) spacer and nonamer in the 5' portion of framework region (FR) 3. Surprisingly, all pseudohybrid joins lacked molecular processing associated with typical VHDJH recombination or nonhomologous end joining. Although inefficient compared to a canonical RSS, the IGHV4 cRSS was a significantly better substrate for in vitro RAG-mediated cleavage than the IGHV3 cRSS. It has been suggested that activation induced cytidine deamination (AICDA) may contribute to VH replacement. However, we found similar secondary rearrangements utilizing IGHV4 genes in AICDA-deficient human B cells. The data suggest that IGHV4 replacement in preimmune human B cells is mediated by an AICDA-independent mechanism resulting from inefficient but selective RAG activity.

Somatic hypermutation (SHM) of Ig genes depends upon the deamination of C nucleotides in WRCY (W=A/T, R=A/G, Y=C/T) motifs by activation-induced cytidine deaminase (AICDA). Despite this, a large number of mutations occur in WA motifs that can be accounted for by the activity of polymerase eta (POL η). To determine whether there are AICDA-independent mutations and to characterize the relationship between AICDA- and POL η-mediated mutations, 1,470 H chain and 1,313 kappa and lambda chain rearrangements from three AICDA−/− patients were analyzed. The Ig mutation frequency of all VH genes from AICDA−/− patients was 40-fold less than that of normal donors whereas the mutation frequency of mutated VH sequences from AICDA−/− patients was 6.8-fold less than normal donors. AICDA−/− B cells lack mutations in WRCY/RGYW motifs as well as replacement mutations and mutational targeting in complementarity determining regions. A significantly reduced mutation frequency in WA motifs compared to normal donors and an increased percentage of transitions, which may relate to reduced uracil DNA-glycosylase (UNG) activity, suggest a role for AICDA in regulating POL η and UNG activity. Similar results were observed in VL rearrangements. The residual mutations were predominantly G:C substitutions, indicating that AICDA-independent cytidine deamination was a likely, yet inefficient, mechanism for mutating Ig genes.

The low affinity IgE receptor, Fc∊RII (CD23), is both a positive and negative regulator of IgE synthesis. The proteinase activity that converts the membrane-bound form of CD23 into a soluble species (sCD23) is an important regulator of the function of CD23 and may be an important therapeutic target for the control of allergy and inflammation. We have characterized the catalytic activity of ADAM (a disintegrin and metalloproteinase) 10 toward human CD23. We found that ADAM10 efficiently catalyzes the cleavage of peptides derived from two distinct cleavage sites in the CD23 backbone. Tissue inhibitors of metalloproteinases and a specific prodomain-based inhibitor of ADAM10 perturb the release of endogenously produced CD23 from human leukemia cell lines as well as primary cultures of human B-cells. Expression of a mutant metalloproteinase-deficient construct of ADAM10 partially inhibited the production of sCD23. Similarly, small inhibitory RNA knockdown of ADAM10 partially inhibited CD23 release and resulted in the accumulation of the membrane-bound form of CD23 on the cells. ADAM10 contributes to CD23 shedding and thus could be considered a potential therapeutic target for the treatment of allergic disease.

Primary Sjögren's syndrome (pSS) is an autoimmune disorder characterized by specific pathological features. A hallmark of pSS is B-cell hyperactivity as manifested by the production of autoantibodies, hypergammaglobulinemia, formation of ectopic lymphoid structures within the inflamed tissues, and enhanced risk of B-cell lymphoma. Changes in the distribution of peripheral B-cell subsets and differences in post-recombination processes of immunoglobulin variable region (IgV) gene usage are also characteristic features of pSS. Comparison of B cells from the peripheral blood and salivary glands of patients with pSS with regard to their expression of the chemokine receptors CXCR4 and CXCR5, and their migratory capacity towards the corresponding ligands, CXCL12 and CXCL13, provide a mechanism for the prominent accumulation of CXCR4+CXCR5+ memory B cells in the inflamed glands. Glandular B cells expressing distinct features of IgV light and heavy chain rearrangements, (re)circulating B cells with increased mutations of cμ transcripts in both CD27- and CD27+ memory B-cell subsets, and enhanced frequencies of individual peripheral B cells containing IgV heavy chain transcripts of multiple isotypes indicate disordered selection and incomplete differentiation processes of B cells in the inflamed tissues in pSS. This may possibly be related to a lack of appropriate censoring mechanisms or different B-cell activation pathways within the ectopic lymphoid structures of the inflamed tissues. These findings add to our understanding of the pathogenesis of this autoimmune inflammatory disorder and may result in new therapeutic approaches.

A major question concerning the immunopathology of rheumatoid arthritis is why the disease is localized to particular joints. A possible explanation could be the presence within the synovium of cells that foster inflammation or easy accessibility of the synovium to migratory disease enhancing cells. Within both the bone marrow and the synovium, fibroblastic stromal cells play an important role in supporting the differentiation and survival of normal cells, and also contribute to the pathologic processes. Among fibroblastic stromal cells in synovial tissue and bone marrow, nurse-like cells are a unique population having the specific capacity to promote pseudoemperipolesis (adhesion and holding beneath) of lymphocytes, and also the ability to promote the growth and function of some populations of lymphocytes and monocytes. Nurse-like cells could therefore contribute to the immunopathogenesis of rheumatoid arthritis, and may contribute to the localization of inflammation within specific joints. The present review considers the evidence that supports these possibilities.

IL-6 is a pleiotropic cytokine involved in both the initiation and the maintenance of the inflammatory and immunologic responses in certain autoimmune diseases. Blocking of these two complementary functions of IL-6 may confer additive, or even unique, benefits to the patient. The levels of both IL-6 and its soluble receptor (sIL-6Rα) are elevated to various degrees in many rheumatic diseases. IL-6 blockade has been shown to be beneficial both in experimental models and in human disease, and inhibition of IL-6 signaling with a molecule such as tocilizumab could prevent or reverse some of the complications typically associated with rheumatic diseases.