Immunospecific reduction of antioligonucleotide antibody-forming cells with a tetrakis-oligonucleotide conjugate (LJP 394), a therapeutic candidate for the treatment of lupus nephritis

Construction of Multivalent Homo- and Heterofunctional ABO Blood Group Glycoconjugates Using a Trifunctional Linker Strategy

The design and synthesis of multivalent ligands displaying complex oligosaccharides is necessary for the development of therapeutics, diagnostics, and research tools. Here, we report an efficient conjugation strategy to prepare complex glycoconjugates with 4 copies of 1 or 2 separate glycan epitopes, providing 4-8 carbohydrate residues on a tetravalent poly(ethylene glycol) scaffold. This strategy provides complex glycoconjugates that approach the size of glycoproteins (15-18 kDa) while remaining well-defined. The synthetic strategy makes use of three orthogonal functional groups, including a reactive N-hydroxysuccinimide (NHS)-ester moiety on the linker to install the first carbohydrate epitope via reaction with an amine. A masked amine functionality on the linker is revealed after the removal of a fluorenylmethyloxycarbonyl (Fmoc)-protecting group, allowing the attachment to the NHS-activated poly(ethylene glycol) (PEG) scaffold. An azide group in the linker was then used to incorporate the second carbohydrate epitope via catalyzed alkyne-azide cycloaddition. Using a known tetravalent PEG scaffold (PDI, 1.025), we prepared homofunctional glycoconjugates that display four copies of lactose and the A-type II or the B-type II human blood group antigens. Using our trifunctional linker, we expanded this strategy to produce heterofunctional conjugates with four copies of two separate glycan epitopes. These heterofunctional conjugates included Neu5Ac, 3'-sialyllactose, or 6'-sialyllactose as a second antigen. Using an alternative strategy, we generated heterofunctional conjugates with three copies of the glycan epitope and one fluorescent group (on average) using a sequential dual-amine coupling strategy. These conjugation strategies should be easily generalized for conjugation of other complex glycans. We demonstrate that the glycan epitopes of heterofunctional conjugates engage and cluster target B-cell receptors and CD22 receptors on B cells, supporting the application of these reagents for investigating cellular response to carbohydrate antigens of the ABO blood group system.

Novel therapies in lupus nephritis

Renal disease continues to cause major morbidity and some mortality for around 30-40% of patients with systemic lupus erythematosus (SLE). Although the combinations of prednisolone and azathioprine or prednisolone and cyclophosphamide have been beneficial to many patients with SLE, they are not always effective and have significant side effects. It is very encouraging that new immunosuppressive drugs such as mycophenolate mofetil and more targeted therapies e.g., anti-CD20 are coming rapidly to larger scale clinical trials. The treatment of lupus nephritis is set to change quite rapidly in the next decade. In this review we highlight the likely major therapeutic advances.

Treatment of systemic lupus erythematosus: new advances in targeted therapy

Treatment for systemic lupus erythematosus (SLE) has traditionally been restricted to broad-based immunosuppression, with glucocorticoids being central to care. Recent insights into lupus pathogenesis promise new, selective therapies with more favorable side effect profiles. The best example of this is belimumab, which targets the B cell cytokine BLyS and has now received Food and Drug Administration (FDA) approval for its use in SLE. Strategies targeting other cytokines, such as interleukin 6 (IL-6) and interferon (IFN)-α, are also on the horizon. Blockade of costimulatory interactions between immune cells offers another opportunity for therapeutic intervention, as do small molecule inhibitors that interfere with cell signaling pathways. We review here the current strategies for SLE treatment, with particular focus on therapies now in active pharmaceutical development. We will also discuss new understandings in lupus pathogenesis that may lead to future advances in therapy.

Lupus nephritis: current update

Lupus nephritis is a major cause of morbidity and mortality in patients with systemic lupus erythematosus. The general consensus is that 60% of lupus patients will develop clinically relevant nephritis at some time in the course of their illness. Prompt recognition and treatment of renal disease is important, as early response to therapy is correlated with better outcome. The present review summarizes our current understanding of the pathogenic mechanisms underlying lupus nephritis and how the disease is currently diagnosed and treated.

Abetimus sodium: a medication for the prevention of lupus nephritis flares

BACKGROUND

Lupus nephritis, one of the most severe and therapeutically challenging manifestations of systemic lupus erythematosus (SLE), has been the target of drug development by La Jolla Pharmaceutical Company. Abetimus sodium, an example of the La Jolla Pharmaceutical Company's Tolerance Technology is an intravenously administered tetrameric oligonucleotide conjugate that safely reduces antidouble-stranded DNA (anti-dsDNA) antibodies. Given the importance of anti-dsDNA antibodies in the pathogenesis of lupus nephritis, the Phase II and III trials were designed to evaluate whether treatment with abetimus sodium could prolong the time to renal flare in cohorts of patients at high risk of nephritic flares.

OBJECTIVE AND METHODS

The available data regarding abetimus were reviewed and the current status of the drug's development program is reported.

CONCLUSIONS

Animal studies have demonstrated the ability of abetimus to reduce the titers of anti-dsDNA antibodies as well as of antidsDNA antibody-secreting cells. Administration of abetimus to patients with SLE has uniformly been associated with reductions in circulating anti-dsDNA antibodies. However, two pivotal trials with large numbers of lupus nephritis patients failed to demonstrate statistically signi ficant prolongations in time to renal flare. An event-driven randomized placebo-controlled trial was abruptly terminated in February 2009 after an interim data safety monitoring board determined that achievement of a successful study outcome was futile.

Lupus nephritis

Lupus nephritis (LN) is one of the common manifestations of systemic lupus erythematosus. Kidney biopsy remains a mainstay of LN diagnosis, which is usually prompted by abnormal urinary sediment, proteinuria, or elevated creatinine. New International Society of Nephrology/Renal Pathology Society classification of LN tends to remove some of the ambiguities of World Health Organization classification and results in better categorization of patients. Although prognosis of LN has improved with the combined use of cytotoxic and steroid therapy, up to 20% of these patients progress to renal failure. Moreover, toxicity of the current regimens remains a major concern. Last few decades have seen a tremendous progress being made in understanding the pathogenesis of LN, but a little has been added to armamentarium against LN, leaving physicians with a few choices. Fortunately, with unfolding of molecular processes involved in disease pathogenesis, new targets for drug therapy have emerged. Whether these medications will prove to be more efficacious and less toxic remains a matter of debate and will be answered by several ongoing trials and future studies.

Molecular therapies for systemic lupus erythematosus: clinical trials and future prospects

The prognosis of patients with systemic lupus erythematosus has greatly improved since treatment regimens combining corticosteroids and immunosuppressive medications have been widely adopted in therapeutic strategies given to these patients. Immune suppression is evidently efficient but also leads to higher susceptibility to infectious and malignant diseases. Toxic effects and sometimes unexpectedly dramatic complications of current therapies have been progressively reported. Identifying novel molecular targets therefore remains an important issue in the treatment of lupus. The aim of this review article is to highlight emerging pharmacological options and new therapeutic avenues for lupus with a particular focus on non-antibody molecular strategies.

Novel strategies for the site-specific covalent labelling of nucleic acids

To broaden the scope of applications in DNA nano- and biotechnology, material science, diagnostics and molecular recognition the functionalization of DNA is of utmost importance. In the last decade many new methods have been developed to achieve this goal. Apart from the direct chemical synthesis of modified DNA by automated phosphoramidite chemistry incorporation of labelled triphosphates and the post-synthetic labelling approach evolved as valuable methods. New bioorthogonal reactions as Diels-Alder, click and Staudinger ligations pushed forward the post-synthetic approach as new insights into DNA polymerase substrate specificity allowed generation and amplification of labelled DNA strands. These novel developments are summarized herein.

Impact of DNA hairpin folding energetics on antibody-ssDNA association

Deposition of anti-DNA antibodies in the kidney contributes to the pathogenesis of the autoimmune disease, systemic lupus erythematosus. Antibodies that bind to hairpin-forming DNA ligands may be particularly prone to deposition. Here we report the first structure of a Fab complexed with hairpin-forming DNA. The ligand used for co-crystallization is 5'-d [CTG(CCTT)CAG]-3', which has a predicted hairpin structure consisting of a four-nucleotide loop (CCTT) and a stem of three base-pairs. The 1.95 A resolution crystal structure of Fab DNA-1 complexed with this ligand shows that the conformation of the bound ligand differs radically from the predicted hairpin conformation. The three base-pairs in the stem are absent in the bound form. The protein binds to the last six nucleotides at the 3' end of the ligand. These nucleotides form a loop (TTCA) closed by a G:C base-pair in the bound state. Stacking of aromatic side-chains against DNA bases is the dominant interaction in the complex. Interactions with the DNA backbone are conspicuously absent. Thermodynamics of binding are examined using isothermal titration calorimetry. The apparent dissociation constant is 4 microM, and binding is enthalpically favorable and entropically unfavorable. Increasing the number of base-pairs in the DNA stem from three to six decreases binding affinity. These data suggest a conformational selection binding mechanism in which the Fab binds preferentially to the unstructured state of the ligand. In this interpretation, the ligand binding and ligand folding equilibria are coupled, with lower hairpin stability leading to greater effective binding affinity. Thus, pre-organization of the DNA loop into the preferred binding conformation does not play a major role in complexation. Rather, it is argued that the stem of the hairpin serves to reduce the degrees of freedom in the free DNA ligand, thereby limiting the entropic cost attendant to complexation with the Fab.

B lymphocytes as therapeutic targets in systemic lupus erythematosus

In recent years, experimental evidence supporting a major role of B cells in the pathogenesis of autoimmune diseases has grown. This includes the discovery of novel mechanisms of autoantibody pathogenicity and the potential of B cells to mediate inflammation and tissue injury. In some instances, engagement of the B cell receptor and other surface receptors is sufficient to stimulate B cells to produce antibody. As a result, B cells have become targets for immunointervention. In lupus, targeting B cell activation factor (BAFF, BLys) indicates that specific blockade of this longevity factor might be sufficient to suppress systemic autoimmunity. Targeting CD20 represents another promising avenue for the treatment of refractory lupus in both adults and children. Although the clinical data add weight to the importance of B cells in the pathogenesis of lupus, new targets for B cell depletion therapy are being investigated. In experimental models, combining CD19 and CD20 antibodies was more effective than either treatment alone.

Update on the treatment of lupus nephritis

Lupus nephritis (LN) is a major cause of morbidity and mortality in patients with systemic lupus erythematosus. Although the use of aggressive immunosuppression has improved both patient and renal survival over the past several decades, the optimal treatment of LN remains challenging. Improved outcomes have come at the expense of significant adverse effects owing to therapy. Moreover with long-term survival, the chronic adverse effects of effective therapies including risk of malignancy, atherosclerosis, infertility, and bone disease all become more important. Finally, some patients fail to achieve remission with standard cytotoxic therapy and others relapse when therapy is reduced. For these reasons, recent clinical trials have attempted to define alternate treatment protocols that appear to be efficacious in achieving and maintaining remission, but with less toxicity than standard regimens. This paper discusses established and newer treatment options for patients with proliferative and membranous LN, with an emphasis on the results of these recent clinical trials. We also review the experimental and human data regarding some of the novel targeted forms of therapy that are under investigation and in different phases of clinical trials.

Abetimus sodium (riquent) for the prevention of nephritic flares in patients with systemic lupus erythematosus

Abetimus sodium has been under development for the treatment of systemic lupus erythematosus since the early 1990s. Because its administration results in the selective reduction of circulating double-stranded DNA antibodies, La Jolla Pharmaceutical Company has focused on the agent's ability to prolong time to nephritic flare. Fourteen trials have been initiated since 1994, but the two pivotal registration trials failed to meet primary end points. The US Food and Drug Administration issued a letter in October 2004 that stated abetimus sodium was "approvable" pending the successful completion of a trial demonstrating clinical benefit. The fate of this agent lies in the ability of the company to successfully complete a phase III study.

Treatment of glomerulonephritis: will we ever have options other than steroids and cytotoxics?

Glomerulonephritis refers to a collection of primary renal disorders and those secondary to a systemic disease, all characterized by inflammation within the glomerulus. Given the underlying immunologic nature of these disorders, they are routinely treated with corticosteriods and various cytotoxic agents. Although in many instances such therapies are successful, they are associated with significant morbidity; as such, alternatives are clearly necessary. Our understanding of the pathogenesis of immunologic glomerular diseases has grown remarkably, in large part from the study of rodent disease models. Fundamental to each disorder is the development of an antigen-specific immune response followed by the effector stage of inflammation. To block the immune response, antigen-specific therapy can be used to induce tolerance, such as through the use of double-stranded DNA molecules in lupus nephritis. Since other antigen systems are less well characterized, inducing a more generalized impairment in the immune response by blocking costimulatory molecules CD40-CD154 and CD28-CD80/86 is a growing approach to treat various immunologic disorders and transplantation. To reduce glomerular inflammation, a variety of effector systems have been targeted, including complement, cytokines/chemokines, adhesion molecules, and mediators of cellular proliferation. Of these, antibodies targeting C5 in the complement system, and antibody and receptor antagonists of tumor necrosis factor-alpha (TNF-alpha) have already been used in glomerular disorders with some promise. Less specific blockade of receptor-mediated events stimulated by platelet-derived growth factors and cell cycle proteins may soon be applied to glomerulonephritis. Finally, interruption of fibrosing pathways, which lead to glomerulosclerosis and interstitial fibrosis common to the end-stage of all glomerulonephritis, is the subject of intense effort which may yield effective biologic therapies. In spite of all these advances, we still are dependent on steroids and cytotoxics to treat glomerulonephritis. To get past this, we must devote significant resources to take observations made in basic research laboratories to develop therapeutics and prove their utility in human disease.

Removal of Pathogenic Autoantibodies by Immunoadsorption

Autoimmune diseases result from disrupted tolerance to self-antigens and subsequent damage to tissues and organs. In several diseases, specific autoantibodies have been either proved or suspected to play a role in this process. Consequently, several strategies have been devised in an attempt to discard the destructive immunoglobulins. Currently, both nonselective and epitope-specific methods are applied in several diseases. In this review, we provide a summary of the available data on elimination of pathogenic autoantibodies and discuss the advantages and pitfalls of the different approaches.

Evidence for Structural Plasticity of Heavy Chain Complementarity-determining Region 3 in Antibody–ssDNA Recognition

Anti-DNA antibodies play important roles in the pathogenesis of autoimmune diseases. They also represent a unique and relatively unexplored class of DNA-binding protein. Here, we present a study of conformational changes induced by DNA binding to an anti-ssDNA Fab known as DNA-1. Three crystal structures are reported: a complex of DNA-1 bound to dT3, and two structures of the ligand-free Fab. One of the ligand-free structures was determined from crystals exhibiting perfect hemihedral twinning, and the details of structure determination are provided. Unexpectedly, five residues (H97-H100A) in the apex of heavy chain complementarity-determining region 3 (HCDR3) are disordered in both ligand-free structures. Ligand binding also caused a 2-4A shift of the backbone of Tyr L92 and ordering of the L92 side-chain. In contrast, these residues are highly ordered in the Fab/dT3 complex, where Tyr H100 and Tyr H100A form intimate stacking interactions with DNA bases, and L92 forms the 5' end of the binding site. The structures suggest that HCDR3 is very flexible and adopts multiple conformations in the ligand-free state. These results are discussed in terms of induced fit and pre-existing equilibrium theories of ligand binding. Our results allow new interpretations of existing thermodynamic and mutagenesis data in terms of conformational entropy and the volume of conformational space accessible to HCDR3 in the ligand-free state. In the context of autoimmune disease, plasticity of the ligand-free antibody could provide a mechanism by which anti-DNA antibodies bind diverse host ligands, and thereby contribute to pathogenicity.

LJP 1082: a toleragen for Hughes syndrome

A hallmark of systemic lupus erythematosus (SLE) and related autoimmune diseases such as the antiphospholipid syndrome (APL or Hughes syndrome) is an apparent breakdown in tolerance, the process by which the body distinguishes self from nonself in order to maintain a versatile immune defense while protecting itself from self-annihilation. To some extent, loss of tolerance is a desirable feature of host immunity, and is known to occur in healthy individuals. Optimal tolerance then is probably not an all or nothing phenomenon. Autoimmunity should be seen as a breakdown in homeostasis rather than a completely aberrant kind of immunity. This leads to special considerations in the assessment of potentially toleragenic therapies, in which an attempt is made to re-educate the immune system. LJP 1082 is designed as a polyvalent antigenic structure aimed at crosslinking specific surface immunoglobulin and tolerizing B cells to beta2-glycoprotein I. Issues of antigenic selection and multiplex forces influencing tolerance and immunity may have impact on its optimal development and use in patients.

Structure of an anti-DNA fab complexed with a non-DNA ligand provides insights into cross-reactivity and molecular mimicry

Antibodies that recognize DNA (anti-DNA) are part of the autoimmune response underlying systemic lupus erythematosus. To better understand molecular recognition by anti-DNA antibodies, crystallographic studies have been performed using an anti-ssDNA antigen-binding fragment (Fab) known as DNA-1. The previously determined structure of a DNA-1/dT5 complex revealed that thymine bases insert into a narrow groove, and that ligand recognition primarily involves the bases of DNA. We now report the 1.75-A resolution structure of DNA-1 complexed with the biological buffer HEPES (4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid). All three light chain complementarity-determining regions (CDRs) and HCDR3 contribute to binding. The HEPES sulfonate hydrogen bonds to His L91, Asn L50, and to the backbone of Tyr H100 and Tyr H100A. The Tyr side-chains of L32, L92, H100, and H100A form nonpolar contacts with the HEPES ethylene and piperazine groups. Comparison to the DNA-1/dT5 structure reveals that the dual recognition of dT5 and HEPES requires a 13-A movement of HCDR3. This dramatic structural change converts the combining site from a narrow groove, appropriate for the edge-on insertion of thymine bases, to one sufficiently wide to accommodate the HEPES sulfonate and piperazine. Isothermal titration calorimetry verified the association of HEPES with DNA-1 under conditions similar those used for crystallization (2 M ammonium sulfate). Interestingly, the presence of 2 M ammonium sulfate increases the affinities of DNA-1 for both HEPES and dT5, suggesting that non-polar Fab-ligand interactions are important for molecular recognition in highly ionic solvent conditions. The structural and thermodynamic data suggest a molecular mimicry mechanism based on structural plasticity and hydrophobic interactions.

Recent advances in the pathogenesis of lupus nephritis: autoantibodies and b cells

Although many factors contribute to the clinical presentation and subsequent course of individuals with lupus nephritis, the formation of glomerular immune deposits is typically one of the initial events. In general, breakdown in immunologic tolerance leads to the production of autoreactive B and T cells that, either through direct infiltration and/or their secretory products, initiate inflammation. Immune deposition within glomeruli results in complement activation and recruitment of inflammatory cells, along with activation of endogenous renal cells. This inflammatory cascade leads to secretion of cytokines and chemokines, which in turn attract more infiltrating cells. Up-regulation of lymphoid-derived chemokines further enhance the cellular influx, augmenting inflammation and resulting in further tissue damage. The degree of inflammation is determined by the extent of this invasion along with both the systemic and local responses to the assault. This review focuses mainly on the contributions of pathogenic autoantibodies, autoreactive B cells to lupus nephritis, and potential immunologic therapies for lupus nephritis. Manipulation of both the cells and soluble mediators that initiate and perpetuate the disease are essential to suppressing autoreactivity and inflammation and preventing disease progression.

Workshop report on some new ideas about the treatment of systemic lupus erythematosus

Our increased understanding of the pathogenesis of systemic lupus erythematosus is leading to new ideas about its therapy. In this session of the workshop the use of LJP 394 a B cell toleragen and the use of an anti-CD20 monoclonal antibody were discussed in some detail. Their rationale and early clinical results were reviewed; both have shown encouraging clinical and serological benefit. Definitive double-blind clinical trials are still, however, awaited. In addition, the intriguing notion of using a nasal instillation of a histone peptide was described and early work in an experimental model presented.

Newer drugs for the treatment of lupus nephritis

This article first reviews the current treatment of lupus nephritis, with a focus on the most serious forms, that is, the proliferative subtypes. Current standards for treatment have been developed empirically. Corticosteroids form the basis of all regimens. Cyclophosphamide given intravenously for prolonged periods is the current gold standard. Azathioprine can be regarded as an effective drug for maintenance treatment of lupus nephritis. Studies on its efficacy in schedules for remission induction are in progress. It has been learned from studies on 'conventional' immunosuppression that randomised, clinical trials should comprise large numbers of patients and a follow-up of many years to elucidate differences between effective strategies. These requirements are not met by any of the 'new' treatments we discuss in this review. There is only limited experience in patients with lupus nephritis with drugs that are currently used for immunosuppression in other autoimmune diseases, such as methotrexate, cyclosporin and high-dose intravenous gammaglobulins, nor with new immunosuppressive drugs that have been developed for immunosuppression in organ transplantation (mycophenolate mofetil, tacrolimus, fludarabine and cladribine). Hormonal therapy with the weak androgen prasterone (dehydroepiandrosterone; DHEA) has no role in treatment of active lupus nephritis. There are interesting experiences with agents that have evolved from progress in immunobiology and in our understanding of immunological processes. These modalities enable more specific immunosuppression and include monoclonal antibodies directed at immune cells, cytokines and components of the complement system, constructs developed to induce tolerance in pathogenic B cells, and gene therapy. Finally, we review data on autologous bone marrow transplantation in patients with systemic lupus erythematosus. We conclude that some strategies (like mycophenolate mofetil) are good candidates for further investigation in large-scale, prospective, randomised trials with prolonged follow-up (which are almost by definition hard to perform). Most new biological agents still are in a pre-clinical phase.

New therapies: plasmapheresis, intravenous immunoglobulin, and monoclonal antibodies

Rheumatologic emergencies may pose a serious threat to life, and the treatment of patients with these illnesses continues to be challenging. In the last decade extensive animal and human research has led to development of new therapies. Considerable progress has been made in the therapy for RA. Newly developed biologic therapies have shown promising results in clinical studies, and two agents have already been approved by the FDA. These drugs are currently available for therapy and are under close postmarketing scrutiny to assess long-term efficacy and safety. Similar therapies are under investigation for SLE. Plasmapheresis, once used for many diseases, is now restricted mostly to conditions for which its use has been shown to be beneficial in randomized, controlled studies. Immunoadsorption is used to target specific disease-producing pathogens for removal during extracorporeal therapy. Evidence is accumulating for the use of IVIGs in several immune-mediated conditions. The outlook for some emergencies continues be grim, however, and various therapies are used based on evidence from anecdotal case reports and case series. The new therapies are relatively safe, but careful monitoring is needed, because there is potential for serious adverse events.

Treatment options for juvenile-onset systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an inflammatory chronic disease characterized by the presence of activated helper T-cells that induce a B-cell response, resulting in the secretion of pathogenic autoantibodies and the formation of immune complexes. SLE in children is a disease of low prevalence with a wide range of clinical manifestations, which means that the number of randomized controlled studies are few and usually involve a small number of patients. In recent years, new therapeutic agents have appeared and the role of older treatments has been clarified. Many of these treatments are designed to reduce inflammation. The spectrum is broad and ranges from traditional nonsteroidal anti-inflammatory drugs (NSAIDs) to cytotoxic agents that have anti-inflammatory effects. The current treatment of children or adults depends on the clinical expression of the disease. Minor manifestations usually respond to the administration of NSAIDs, low doses of corticosteroids, hydroxychloroquine, or methotrexate. Thalidomide could be used for refractory skin lesions. Major manifestations can endanger the patient's life and require early, aggressive treatment. Kidney disease and other manifestations have been related to the formation or deposit of tissular immune complexes. Therefore, for years the main aim of treatment has been to suppress the immune response. The immunosuppressant treatments used in children with SLE include high doses of corticosteroids, azathioprine, methotrexate, cyclosporine, and cyclophosphamide. Several combinations of medications have been used to obtain a rapid remission or to reduce the risk of toxicity of prolonged administration of cytotoxic agents. Intravenous gamma-globulin has been successfully used in the treatment of lupus nephritis, vasculitis, and acute thrombocytopenia. In spite of numerous published studies, the use of these drugs is still controversial. The immunosuppression achieved with these treatments is nonspecific, not always effective, and associated with significant toxicities; the most significant being growth retardation, accelerated atherosclerosis and severe infectious complications. The purpose of new biological therapies is to achieve specific immunosuppression, which makes it possible to design more effective and less toxic therapeutic strategies. Mycophenolate mofetil is a promising alternative in patients who do not respond to high doses of cyclophosphamide or azathioprine. Some recently developed monoclonal antibodies such as anti-CD40L or anti-IL-10, or other molecules such as LJP394 may prove useful in the near future. Finally, stem cell transplantation may be proposed in patients with severe juvenile-onset SLE who do not respond to any treatment.

Novel therapeutic agents for systemic lupus erythematosus

The last significant breakthrough in the treatment of systemic lupus erythematosus (SLE) was the use of cyclophosphamide and methylprednisolone in the treatment of lupus nephritis. Recent advances in immunology, oncology, and endocrinology have resulted in many potential therapies for SLE. These therapies include new immunosuppressants, biologic medications, tolerizing agents, immunoablation techniques, and hormonal medications. Each of these approaches will be discussed in this review. Some therapies are currently in use in clinical rheumatology practice (mycophenolate mofetil) and others are entering phase I trials (anti-BLyS monoclonal antibody). While some of these new therapies target specific inflammatory mechanisms in SLE (anti-CD40L monoclonal antibody), others work by nonspecific inhibition of the immune system (immunoablation).

Pre-treatment affinity for LJP 394 influences pharmacodynamic response in lupus patients

Five prospective clinical studies in lupus patients have shown that LJP 394 can reduce circulating anti-dsDNA antibody levels without causing generalized immunosuppression. The compound is currently being evaluated in a phase III clinical trial for the prevention of renal flares in patients with high-affinity antibodies to LJP 394 and a history of lupus nephritis. The current study analyzed the affinity of patient IgG for LJP 394 prior to and following 4 months of treatment with LJP 394 to determine if pretreatment affinity influenced pharmacodynamic response. Patient serum samples from a multicenter, double-blind, placebo-controlled trial were evaluated prior to and following 4 months of weekly, biweekly or monthly treatment with placebo (n = 9) or weekly treatment with 10 mg LJP 394 (n = 6) or 50 mg LJP 394 (n = 4). After treatment there was a dose-dependent reduction in affinity in the 10 mg/week and 50 mg/week groups (P < 0.05 and P < 0.01, respectively), whereas the placebo group was unchanged. This study demonstrates that weekly treatment with LJP 394 produces a dose-dependent reduction in titer-weighted average affinity. These results suggest it may be possible to use an affinity assay to define prospectively patients that are most likely to exhibit the desired pharmacodynamic response to LJP 394.

Therapy of systemic lupus erythematosus: a look into the future

The prognosis for patients with systemic lupus erythematosus has greatly improved over the past two decades. However, therapies that are more effective and that have fewer sequelae are needed to rescue patients from organ failure and further reduce mortality. Research under way, including that into induction of tolerance to self-antigens, prevention of the consequences of pathogenic autoantibody production, interference with the cytokine network and signal transduction, the identification and treatment of any infectious triggers, and stem cell therapy, offers hope of improved remedies or even of cure. Given the fact that a number of biological therapies for rheumatologic disease are already in use or are in the development stage, such progress may come soon.

Monoclonal antibodies and other biologic therapies

The treatment of systemic lupus erythematosus (SLE) presents a significant therapeutic challenge: multi-organ involvement and a variable disease course characterized by clinical exacerbations and remissions make it difficult to predict outcome. Few products have been specifically developed in this clinical indication and most accepted therapies have not been tested in randomized controlled trials in SLE. A variety of biologic agents under investigation as potential treatments for SLE are designed to interfere with specific immunologic responses, hopefully avoiding generalized immunosuppression. These include therapies to downregulate IL-10 and/or upregulate TGFb production. Agents which interfere with T cell activation and T cell-B cell collaboration, such as CTLA4-Ig and anti-CD40 ligand monoclonal antibodies, may result in long term therapeutic benefit; alone or in combination, even following brief treatment courses. Products designed to decrease production of anti-dsDNA antibodies or inhibit complement activation may prevent immune complex deposition and amerliorate organ-specific manifestations such as renal disease. More aggressive interventions include gene therapy and stem cell transplantation. As these agents enter clinical trials, efforts to develop international consensus regarding trial methodology and outcome measures will be crucial to their successful development.

T cell and B cell tolerance to GALalpha1,3GAL-expressing heart xenografts is achieved in alpha1,3-galactosyltransferase-deficient mice by nonmyeloablative induction of mixed chimerism

BACKGROUND

We have previously demonstrated that mixed xenogeneic chimerism and donor-specific T-cell tolerance can be induced in the rat-to-mouse species combination by using a relatively nontoxic, nonmyeloablative conditioning regimen. However, natural antibodies (NAbs) against Galalpha1,3Gal (Gal) pose an additional major barrier to pig-to-human vascularized xenograft acceptance.

METHODS

To determine whether the mixed chimerism approach could also overcome this humoral barrier, T cell-depleted rat (GalT+/+) bone marrow cells (BMC) were transplanted to alpha1,3-galactosyltransferase deficient (GalT-/-) mice conditioned with a nonmyeloablative regimen, consisting of transient T cell and natural killer (NK) cell depletion, 3 Gy whole body irradiation, and 7 Gy thymic irradiation.

RESULTS

By giving a high dose (180x106) of rat BMC, persistent mixed chimerism could be induced in GalT-/- mice, although the level of donor-type hematopoietic repopulation declined over time. Induction of mixed chimerism was associated with a rapid disappearance of anti-Gal and anti-rat NAb in the sera. Both anti-Gal Ab-producing cells and B cells with receptors recognizing Gal were undetectable in mixed chimeras, even when the chimerism levels declined, suggesting that a very low level of chimerism could effectively maintain B-cell tolerance to Gal, probably by clonal deletion and/or receptor editing. Mixed chimeras accepted subsequently transplanted donor-type rat hearts (>100 days) without immunosuppressive therapy, whereas delayed vascular and even hyperacute rejection of rat hearts occurred in conditioned control GalT-/- mice. Cellular rejection occurred by 5-6 days in conditioned control wild-type mice.

CONCLUSIONS

These findings demonstrate that induction of mixed chimerism with a nonmyeloablative regimen can prevent vascularized xenograft rejection by cellular and anti-Gal Ab-dependent pathways in GalT+/+-to-GalT-/- species combinations.

Treatment of systemic lupus erythematosus

The treatment of systemic lupus erythematosus (SLE) is mainly based on a number of "traditional" drugs such as corticosteroids, antimalarials, azathioprine and cyclophosphamide. However, this scenario is rapidly changing due to the introduction of new compounds. Some of these new agents have been successfully used in other diseases, while others are being specifically designed to interfere with the immune abnormalities seen in SLE. As our knowledge on the mechanisms of immune response increases, new drugs that can interfere with T and B cell interaction and activation, production of anti-dsDNA autoantibodies, immune-complexes deposition and cytokine activation have been developed and some of these are now under investigation in SLE. Although initial data regarding their safety and efficacy are encouraging, caution must be taken before these drugs are considered as the treatment of choice for specific SLE manifestations. Specifically, controlled clinical trials with sufficient number of patients are necessary. If the promising results already available are confirmed, the use of these drugs might represent the keystone in the future management of SLE and other autoimmune diseases.

Advances in the treatment of lupus nephritis

Systemic lupus erythematosus (SLE) is an autoimmune disease that leads to the formation and deposition of immune complexes throughout the body, which are pathogenic for the disease. Different forms of glomerulonephritis can occur in patients with SLE and can contribute significantly to the associated morbidity and, ultimately, mortality from the disease. Over the past two decades, there have been significant strides in our understanding of the disease and in treatments that attempt to control the formation and deposition of anti-DNA auto-antibodies and immune complexes, as well as the subsequent inflammatory cascade mediated through various cellular and humoral pathways leading to progressive renal damage and end-stage renal disease. In this chapter, we review the current understanding of the pathogenesis and treatment of lupus nephritis in its various stages and discuss the experimental and human data regarding some of the potential newer forms of therapy. We discuss data regarding the use of steroids, azathioprine, cyclophosphamide, cyclosporine A, mycophenolate mofetil, gammaglobulin, plasmapheresis, LJP 394, flaxseed oil, bindarit, anti-CD40 ligand, and CTLA4Ig.

Covalent modification and surface immobilization of nucleic acids via the Diels-Alder bioconjugation method

The importance of chemically modified and surface immobilized nucleic acids has inspired the development of a wide variety of complementary techniques for covalent oligonucleotide preparation and immobilization. We are developing technology based on the use of a Diels-Alder reaction for accomplishing the covalent modification of oligonucleotides. Reported herein is preliminary progress toward the establishment of robust reagents for introducing the reactive functionality, as well as studies employing the BIACORE system to demonstrate surface immobilization by the method.

Synthetic multivalent ligands in the exploration of cell-surface interactions

Processes such as cell-cell recognition and the initiation of signal transduction often depend on the formation of multiple receptor-ligand complexes at the cell surface. Synthetic multivalent ligands are unique probes of these complex cell-surface-binding events. Multivalent ligands can be used as inhibitors of receptor-ligand interactions or as activators of signal transduction pathways. Emerging from these complementary applications is insight into how cells exploit multivalent interactions to bind with increased avidity and specificity and how cell-surface receptor organization influences signaling and the cellular responses that result.

Genetics of systemic lupus erythematosus. Clinical implications

Rheumatic diseases have long been recognized as having complex inheritance patterns. It has recently been estimated that over 100 genes may be implicated in the SLE disease process. Identification of these genes has led to a greater understanding of the etiopathogenesis of SLE and is beginning to lead to new types of interventions directed at correcting aberrant biological processes.

New therapies for systemic lupus erythematosus

New therapies for the treatment of SLE have gained increased attention, as demonstrated by a growing number of new modalities being studied. These modalities include novel biologic agents that target specific immunologic responses and more traditional pharmaceutical agents. This article summarizes these new therapies and briefly discusses their mechanisms of action and the most recent research performed to characterize their safety and efficacy.

Dehydroepiandrosterone and biologics in the treatment of systemic lupus erythematosus

Our understanding of the immune system in health and disease has greatly increased over this past decade. An outgrowth of this burgeoning knowledge has been the discovery of novel strategies to treat a variety of autoimmune diseases. As a result, significant advances have been made in the treatment of arthritis with a half-dozen new treatments approved between September, 1998 and November, 1999. Although no new therapies have been approved for the treatment of systemic lupus erythematosus (SLE), this decade has witnessed an unprecedented amount of activity in drug development for this disease. This article specifically addresses the current status of drug development in the area of hormonal and biologic therapies for SLE.

Antibody affinities and relative titers in polyclonal populations: surface plasmon resonance analysis of anti-DNA antibodies

This paper presents the equations and methodology for the measurement and interpretation of apparent dissociation constants for polyclonal populations of antibodies, where antigen is kept trace relative to antibody concentration. Surface plasmon resonance is used to determine K(d)s for the binding of anti-DNA antibodies to trace amounts of DNA antigen on a chip. Since the approach taken relies on equilibrium measurements, kinetic mass transport artifacts are avoided. The apparent K(d) is a weighted average of all the K(d)s for the clonally related subpopulations within the polyclonal pool, where each weighting factor is the relative titer (fractional presence) of the subpopulation. Titration curves appear as if there is one monoclonal population with that titer-weighted-average K(d). Implications of changes in the antibody affinity distribution within the population are discussed. The equations described herein provide a better physical understanding of the apparent K(d) that is obtained when a heterogeneous population of receptors is titrated against a trace ligand.

Anti-DNA autoantibodies and systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that affects most of the organs and tissues of the body, causing glomerulonephritis, arthritis, and cerebritis. SLE can be fatal with nephritis, in particular, predicting a poor outcome for patients. In this review, we highlight what has been learned about SLE from the study of mouse models, and pay particular attention to anti-DNA autoantibodies, both as pathological agents of lupus nephritis and as DNA-binding proteins. We summarize the current approaches used to treat SLE and discuss the targeting of anti-DNA autoantibodies as a new treatment for lupus nephritis.

Pharmacological intervention in antibody mediated disease

The use of single signal anergy to inactive pathological B cells in an antigen-specific manner is discussed. Cross-linking surface immunoglobulin, with a construct which contains oligovalent B cell epitopes on a non-immunogenic molecular framework can be used to inactivate the target B cells if the construct lacks T cells epitopes. An example of such a B cell toleragen is LJP 394, which inactivates anti-dsDNA-specific B cells in vivo in murine immunized and spontaneous disease models. The drug enhances survival and lowers renal pathology in BXSB mice. Appropriate definition of epitopes of pathological (auto) antibodies thus offers an opportunity for pharmacological intervention.