Treatment of murine lupus with cDNA encoding IFN-gammaR/Fc

Electroporation for targeted gene transfer

The utilisation of nonviral gene delivery methods has been increasing steadily, however, a drawback has been the relative low efficiency of gene transfer with naked DNA compared with viral delivery methods. In vivo electroporation, which has previously been used clinically to deliver chemotherapeutic agents, also enhances the delivery of plasmid DNA and has been used to deliver plasmids to several tissue types, particularly muscle and tumour. Recently, a large number of preclinical studies for a variety of therapeutic modalities have demonstrated the potential of electrically mediated gene transfer. Although clinical trials using gene transfer with in vivo electroporation have not as yet been realised, the tremendous growth of this technology suggests that the first trials will soon be initiated.

Gene therapy of diabetes using a novel GLP-1/IgG1-Fc fusion construct normalizes glucose levels in db/db mice

Glucagon-like peptide (GLP-1), a major physiological incretin, plays numerous important roles in modulating blood glucose homeostasis and has been proposed for the treatment of type 2 diabetes. The major obstacles for using native GLP-1 as a therapeutic agent are that it must be delivered by a parenteral route and has a short half-life. In an attempt to develop a strategy to prolong the physiological t(1/2) and enhance the potency of GLP-1, a fusion protein consisting of active human GLP-1 and mouse IgG(1) heavy chain constant regions (GLP-1/Fc) was generated. A plasmid encoding an IgK leader peptide-driven secretable fusion protein of the active GLP-1 and IgG(1)-Fc was constructed for mammalian expression. This plasmid allows for expression of bivalent GLP-1 peptide ligands as a result of IgG-Fc homodimerization. In vitro studies employing purified GLP-1/Fc indicate that the fusion protein is functional and elevates cAMP levels in insulin-secreting INS-1 cells. In addition, it stimulates insulin secretion in a glucose concentration-dependent manner. Intramuscular gene transfer of the plasmid in db/db mice demonstrated that expression of the GLP-1/Fc peptide normalizes glucose tolerance by enhancing insulin secretion and suppressing glucagon release. This strategy of using a bivalent GLP-1/Fc fusion protein as a therapeutic agent is a novel approach for the treatment of diabetes.

Roles of genetic variations in signalling/immunoregulatory molecules in susceptibility to systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with a complex genetic basis that includes many susceptibility genes on multiple chromosomes. As complex human diseases like SLE involve multiple, interacting genetic and environmental determinants, identifying genes for complex traits is challenging and has had limited success so far. However, recent advances in genetic resources and technology have been providing new tools to identify the novel pathways or the sequence variants that contribute to autoimmune diseases. During the past several years, several new candidate genes have been implicated in development of SLE though association studies. In this article we describe an overview of the latest findings in the genetics of SLE, especially focusing on the genetic variations in the signalling or immunoregulatory molecules including CD28 and IRF family members.

Interferon pathway activation in systemic lupus erythematosus

The recognition that a multitude of interferon (IFN)- inducible genes are coordinately expressed in peripheral blood cells of patients with systemic lupus erythematosus (SLE) has contributed to considerable interest in the IFN pathway as a therapeutic target in lupus. Together with data that have accumulated over the past four decades implicating IFN-alpha in SLE, the gene expression data have resulted in emergence of this cytokine pathway as a focal point for understanding mechanisms of autoimmunity and inflammation in systemic autoimmune diseases. Assays that measure IFN-inducible gene expression in patient cells and tissues and plasma assays that quantify IFN-alpha protein are providing tools for identification of patients with active disease and who may be responsive to inhibition of the innate immune system component of the altered immune response in SLE. In addition, investigations of the mechanisms of induction of IFN pathway activation are suggesting clues to the triggers of autoimmunity in SLE.

Expression and function of inducible co-stimulator in patients with systemic lupus erythematosus: possible involvement in excessive interferon-gamma and anti-double-stranded DNA antibody production

Inducible co-stimulator (ICOS) is the third member of the CD28/cytotoxic T-lymphocyte associated antigen-4 family and is involved in the proliferation and activation of T cells. A detailed functional analysis of ICOS on peripheral blood T cells from patients with systemic lupus erythematosus (SLE) has not yet been reported. In the present study we developed a fully human anti-human ICOS mAb (JTA009) with high avidity and investigated the immunopathological roles of ICOS in SLE. JTA009 exhibited higher avidity for ICOS than a previously reported mAb, namely SA12. Using JTA009, ICOS was detected in a substantial proportion of unstimulated peripheral blood T cells from both normal control individuals and patients with SLE. In CD4⁺CD45RO⁺ T cells from peripheral blood, the percentage of ICOS⁺ cells and mean fluorescence intensity with JTA009 were significantly higher in active SLE than in inactive SLE or in normal control individuals. JTA009 co-stimulated peripheral blood T cells in the presence of suboptimal concentrations of anti-CD3 mAb. Median values of [³H]thymidine incorporation were higher in SLE T cells with ICOS co-stimulation than in normal T cells, and the difference between inactive SLE patients and normal control individuals achieved statistical significance. ICOS co-stimulation significantly increased the production of IFN-γ, IL-4 and IL-10 in both SLE and normal T cells. IFN-γ in the culture supernatants of both active and inactive SLE T cells with ICOS co-stimulation was significantly higher than in normal control T cells. Finally, SLE T cells with ICOS co-stimulation selectively and significantly enhanced the production of IgG anti-double-stranded DNA antibodies by autologous B cells. These findings suggest that ICOS is involved in abnormal T cell activation in SLE, and that blockade of the interaction between ICOS and its receptor may have therapeutic value in the treatment of this intractable disease.

Membranous glomerulonephritis development with Th2-type immune deviations in MRL/lpr mice deficient for IL-27 receptor (WSX-1)

MRL/lpr mice develop spontaneous glomerulonephritis that is essentially identical with diffuse proliferative glomerulonephritis (World Health Organization class IV) in human lupus nephritis. Lupus nephritis is one of the most serious complications of systemic lupus erythematosus. Diffuse proliferative glomerulonephritis is associated with autoimmune responses dominated by Th1 cells producing high levels of IFN-gamma. The initial mounting of Th1 responses depends on the function of the WSX-1 gene, which encodes a subunit of the IL-27R with homology to IL-12R. In mice deficient for the WSX-1 gene, proper Th1 differentiation was impaired and abnormal Th2 skewing was observed during infection with some intracellular pathogens. Disruption of the WSX-1 gene dramatically changed the pathophysiology of glomerulonephritis developing in MRL/lpr mice. WSX-1-/- MRL/lpr mice developed disease resembling human membranous glomerulonephritis (World Health Organization class V) with a predominance of IgG1 in glomerular deposits, accompanied by increased IgG1 and IgE in the sera. T cells in WSX-1-/- MRL/lpr mice displayed significantly reduced IFN-gamma production along with elevated IL-4 expression. Loss of WSX-1 thus favors Th2-type autoimmune responses, suggesting that the Th1/Th2 balance may be a pivotal determinant of human lupus nephritis development.

Amelioration of SLE-like manifestations in (NZBxNZW)F1 mice following treatment with a peptide based on the complementarity determining region 1 of an autoantibody is associated with a down-regulation of apoptosis and of the pro-apoptotic factor JNK kinase

Treatment with peptides based on the complementarity determining regions (CDR) of murine and human monoclonal anti-DNA antibodies that bear the common idiotype, 16/6 Id, ameliorates disease manifestations of mice with either induced or spontaneous SLE. Aberrant expression and function of the p21Ras/MAP kinase pathway are associated with active SLE. Therefore, we examined the effect of treatment with a CDR1-based peptide of a human autoantibody (hCDR1) on the p21Ras pathway and SLE manifestations of SLE-prone (NZBxNZW)F1 mice. Untreated SLE-afflicted mice demonstrated increased expression of p21Ras and the phosphorylated active form of its down-stream element JNK kinase in conjunction with reduced hSOS and unchanged p120GAP, as compared to healthy controls. Amelioration of SLE manifestations following treatment with hCDR1 was associated with a diminished expression of phosphorylated JNK kinase, mainly in the T cell population that also exhibited reduced rates of apoptosis. Thus, hCDR1 therapy ameliorates SLE, at least in part, via down-regulation of the activity of the pro-apoptotic JNK kinase.

Therapeutic antibody gene transfer: an active approach to passive immunity

Advances in gene transfer approaches are enabling the possibility of applying therapeutic antibodies using DNA. In particular gene transfer in combination with electroporation is promising and can result in generating in vivo antibody concentrations in the low therapeutic range. However, several important problems need to be dealt with before antibody gene transfer can become a valuable supplement to the current therapies. As antibody production following gene transfer is difficult to control, the danger of inducing autoimmune conditions or uncontrollable side effects occurs in cases in which autologous antigens are targeted. It is suggested that the most promising area of application therefore appears to be infectious disease in which heterologous antigens are targeted and concerns for long-term antibody exposure are minimal. Finally, genes encoding fully human antibodies will enhance long-term expression and decrease problems linked to immunogenicity.

Signaling through up-regulated C3a receptor is key to the development of experimental lupus nephritis

Signaling of the C3a anaphylatoxin through its G protein-coupled receptor, C3aR, is relevant in a variety of inflammatory diseases, but its role in lupus nephritis is undefined. In this study, we show that expression of C3aR was significantly increased in prediseased and diseased kidneys of MRL/lpr lupus mice compared with MRL/+ controls. To investigate the role of C3aR in experimental lupus, a small molecule antagonist of C3aR (C3aRa) was administered continuously to MRL/lpr mice from 13 to 19 wk of age. All 13 C3aRa-treated mice survived during the 6-wk treatment compared with 9 of 14 (64.3%) control animals given vehicle (p = 0.019). Relative to controls, C3aRa-treated animals were protected from renal disease as measured by albuminuria (p = 0.040) and blood urea nitrogen (p = 0.021). In addition, there were fewer neutrophils, monocytes, and apoptotic cells in the kidneys of C3aRa-treated mice. C3aRa treatment also led to reduced renal IL-1beta and RANTES mRNA and phosphorylated phosphatase and tensin homologue deleted on chromosome 10 protein, whereas the mass of phosphorylated protein kinase B/Akt was increased by C3aRa. Thus, C3aR antagonism significantly reduces renal disease in MRL/lpr mice, which further translates into prolonged survival. These data illustrate that C3aR is relevant in experimental lupus nephritis and may be a target for therapeutic intervention in the human disease.

Sustained low-level expression of interferon-gamma promotes tumor development: potential insights in tumor prevention and tumor immunotherapy

Although the proinflammatory cytokine interferon-gamma (IFN-gamma) has been generally thought to enhance antitumor immune responses and be involved in antitumor mechanisms of many other immunotherapy molecules, it has also been reported that IFN-gamma could promote tumor immune evasion. In this report, by using an ideal mouse model that expresses IFN-gamma locally in muscle, we demonstrate that sustained low-level expression of IFN-gamma promotes the development of several types of tumor including H22 hepatoma, MA782/5S mammary adenocarcinoma and B16 melanoma. However, transitory expression of IFN-gamma does not have such an effect. On the other hand, sustained high-level expression of IFN-gamma mediates significant antitumor effect on H22 hepatoma. Low level of IFN-gamma upregulates expression of PD-L1, PD-L2, CTLA-4 and Foxp3, which may partly account for the tumor immune evasion promoted by IFN-gamma. Furthermore, blockade of PD-L inhibits IFN-gamma's tumor-promoting effect. Our findings provide a mechanistic link between chronic inflammation and cancer and would have potential implications for cancer prevention and also for the design of cytokine-based cancer immunotherapy.

DNA vaccination with an insulin construct and a chimeric protein binding to both CTLA4 and CD40 ameliorates type 1 diabetes in NOD mice

Type 1 diabetes (T1D), a T-cell-mediated autoimmune disease, could be attributed to many defects in nonobese diabetic (NOD) mice, including deficient expressions of costimulatory molecules that impair antigen presentation. Thus, this deficient antigen presentation may result in a reduced ability to induce a tolerogenic response through negative selection/regulation of autoreactive T cells. Improperly activated T cells seem to be able to induce autoimmune responses causing diabetes. To re-establish tolerance to autoantigens by modulating costimulation, we constructed and tested a new type of DNA vaccine encoding a membrane-bound preproinsulin (mbPPI) and a chimeric gene vector encoding mutant B7.1/CD40L (mB7.1/CD40L) fusion protein. This mutant B7.1 binds CTLA4 but not CD28. We report that young NOD mice immunized with mbPPI along with mB7.1/CD40L DNA vectors significantly reduced diabetes incidence while treatment with CTLA4/IgG1 exacerbated diabetes. In conclusion, the combination of mbPPI and mB7.1/CD40L was able to protect against autoimmunity and diabetes in NOD mice possibly by promoting a more efficient presentation of autoantigen PPI and inducing specific tolerance to PPI by negatively regulating autoreactive T cells.

C5a promotes development of experimental lupus nephritis which can be blocked with a specific receptor antagonist

The MRL/lpr murine SLE model has widespread complement activation and deposition of complement fragments in affected tissues. The potent anaphylatoxin C5a has the potential to play a key role in the pathogenesis of lupus nephritis. We found that renal expression of C5aR mRNA and protein was significantly increased in MRL/lpr mice compared to control MRL/+ mice. To examine the role of C5a signaling through C5aR, a specific small molecule antagonist (a) of C5aR was administered continuously to MRL/lpr mice from 13 to 19 wks of age. Littermate controls were given vehicle alone. The progressive impairment in renal function exhibited in the control group was prevented by C5aRa treatment. Infiltration of neutrophils and macrophages into kidneys was significantly reduced in animals treated with C5aRa compared to controls. Furthermore, renal expression of IL-1beta and MIP-2 mRNA as well as the extent of apoptosis were significantly decreased with blockade of C5aR, indicating their dependence upon signals delivered through C5aR. Thus, pharmacological blockade of C5aR reduces disease manifestations in experimental lupus nephritis. These data support an important role for the C5a anaphylatoxin in lupus nephritis, and that blockade of C5aR represents a potentially viable treatment for human lupus nephritis.

Anti-Vascular Endothelial Growth Factor Gene Therapy Attenuates Lung Injury and Fibrosis in Mice

Vascular endothelial growth factor (VEGF) is an angiogenesis factor with proinflammatory roles. Flt-1 is one of the specific receptors for VEGF, and soluble flt-1 (sflt-1) binds to VEGF and competitively inhibits it from binding to the receptors. We examined the role of VEGF in the pathophysiology of bleomycin-induced pneumopathy in mice, using a new therapeutic strategy that comprises transfection of the sflt-1 gene into skeletal muscles as a biofactory for anti-VEGF therapy. The serum levels of sflt-1 were significantly increased at 3-14 days after the gene transfer. Transfection of the sflt-1 gene at 3 days before or 7 days after the intratracheal instillation of bleomycin decreased the number of inflammatory cells, the protein concentration in the bronchoalveolar lavage fluid and with von Willebrand factor expression at 14 days. Transfection of the sflt-1 gene also attenuated pulmonary fibrosis and apoptosis at 14 days. Since the inflammatory cell infiltration begins at 3 days and is followed by interstitial fibrosis, it is likely that VEGF has important roles as a proinflammatory, a permeability-inducing, and an angiogenesis factor not only in the early inflammatory phase but also in the late fibrotic phase. Furthermore, this method may be beneficial for treating lung injury and fibrosis from the viewpoint of clinical application, since it does not require the use of a viral vector or neutralizing Ab.

Autoimmune alterations induced by the New Zealand Black Lbw2 locus in BWF1 mice

The New Zealand Black (NZB) Lbw2 locus (lupus NZB x New Zealand White (NZW) 2 locus) was previously linked to mortality and glomerulonephritis, but not to IgG autoantibodies, suggesting that it played a role in a later disease stage. To define its contribution, (NZB x NZW)F1 hybrids (BWF1) containing two, one, or no copies of this locus were generated. Lack of the NZB Lbw2 indeed reduced mortality and glomerulonephritis, but not serum levels of total and anti-DNA IgG Abs. There were, however, significant reductions in the B cell response to LPS, total and anti-DNA IgM and IgG Ab-forming cells, IgM Ab levels, and glomerular Ig deposits. Furthermore, although serum IgG autoantibody levels correlated poorly with kidney IgG deposits, the number of spontaneous IgG Ab-forming cells had a significant correlation. Genome-wide mapping of IgM anti-chromatin levels identified only Lbw2, and analysis of subinterval congenics tentatively reduced Lbw2 to approximately 5 Mb. Because no known genes associated with B cell activation and lupus are in this interval, Lbw2 probably represents a novel B cell activation gene. These findings establish the importance of Lbw2 in the BWF1 hybrid and indicate that Lbw2, by enhancing B cell hyperactivity, promotes the early polyclonal activation of B cells and subsequent production of autoantibodies.

Interferons as pathogenic effectors in autoimmunity

Interferons (IFNs) type-1 (IFN alpha/beta) and type-II (IFN-gamma) are the most pleiotropic molecules in the intricate cytokine network. This dominance arises from three crucial factors: (i) initiation of IFN-alpha/beta and IFN-gamma production at the inception of most innate immune responses, which primes for the ensuing adaptive immune responses, primarily through the sine qua non upregulation of major histocompatibility complex and costimulatory molecules; (ii) magnification of their production and signaling by cross-talk between themselves, and synergistic or antagonistic effects on other cytokines; and (iii) direct or indirect initiation of transcription of hundreds of immunologically relevant genes. Considering that aberrant immune responses against self-molecules seem to depend on the same constituents and pathways as those against exogenous antigens, it follows that IFNs are also major effectors in the pathogenesis of autoimmunity. Here, we review the diverse biological effects of IFNs on the immune system, discuss findings pertaining to the nature of exogenous and endogenous stimuli that might induce IFN production through the engagement of Toll-like receptors, and summarize the detrimental and, in some instances, beneficial effects of IFNs in systemic and organ-specific autoimmune diseases.

IFN-α Induces Early Lethal Lupus in Preautoimmune (New Zealand Black × New Zealand White)F1but Not in BALB/c Mice

Recent studies indicate that IFN-alpha is involved in pathogenesis of systemic lupus erythematosus. However, direct proof that IFN-alpha is not only necessary, but also sufficient to induce lupus pathogenicity is lacking. In this study, we show that in vivo adenovector-mediated delivery of murine IFN-alpha results in preautoimmune (New Zealand Black (NZB) x New Zealand White (NZW))F(1), but not in normal, mice, in a rapid and severe disease with all characteristics of systemic lupus erythematosus. Anti-dsDNA Abs appeared as soon as day 10 after initiation of IFN-alpha treatment. Proteinuria and death caused by glomerulonephritis occurred in all treated mice within, respectively, approximately 9 and approximately 18 wk, at a time when all untreated (NZB x NZW)F(1) did not show any sign of disease. IFN-alpha in vivo induced an overexpression of B lymphocyte stimulator in circulation at similar levels in both the preautoimmune and the normal mouse strains. All effects elicited by IFN-alpha were dose dependent. (NZB x NZW)F(1) infused with purified murine IFN-alpha also showed acceleration of lupus. Thus, prolonged expression of IFN-alpha in vivo induces early lethal lupus in susceptible animals.

Defects in the interferon-gamma and interleukin-12 pathways

The interferon-gamma (IFN-gamma)/interleukin-12 (IL-12) pathway is a pivotal player in the immune system and is central to controlling mycobacterial infections. We highlight the most recent and relevant advances in understanding this pathway and their repercussions on basic and clinical science. Human mutations in IFN-gamma receptor-1 (IFN-gammaR1), IFN-gammaR2, IL-12p40, IL-12 receptor-beta1, signal transducer and activator of transcription-1, and nuclear factor-kappaB essential modulator are analyzed in the context of genetic susceptibility to mycobacterial diseases. A diagnostic and therapeutic approach is described. The IFN-gamma/IL-12 pathway is central in immune control of both environmental and autochthonous challenges, as reflected in human mutations and animal models. Besides being crucial for mycobacterial control, the IFN-gamma/IL-12 pathway is also involved in the pathogenesis of autoimmune disease as well as tumor development and control. Genotype-phenotype correlations have been established for certain genes in this pathway, some of which have therapeutic implications.

Coordinate overexpression of interferon-alpha-induced genes in systemic lupus erythematosus

OBJECTIVE

To study the contribution of interferon-alpha (IFNalpha) and IFNgamma to the IFN gene expression signature that has been observed in microarray screens of peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE).

METHODS

Quantitative real-time polymerase chain reaction analysis of healthy control PBMCs was used to determine the relative induction of a panel of IFN-inducible genes (IFIGs) by IFNalpha and IFNgamma. PBMCs from 77 SLE patients were compared with those from 22 disease controls and 28 healthy donors for expression of IFIGs.

RESULTS

Expression of IFNalpha-inducible genes was significantly higher in SLE PBMCs than in those from disease controls or healthy donors. The level of expression of all IFIGs in PBMCs from SLE patients with IFNalpha pathway activation correlated highly with the inherent responsiveness of those genes to IFNalpha, suggesting coordinate activation of that cytokine pathway. Expression of genes preferentially induced by IFNgamma was not significantly increased in SLE PBMCs compared with control PBMCs. IFNalpha-regulated gene-inducing activity was detected in some SLE plasma samples.

CONCLUSION

The coordinate activation of IFNalpha-induced genes is a characteristic of PBMCs from many SLE patients, supporting the hypothesis that IFNalpha is the predominant stimulus for IFIG expression in lupus.

Lessons learned from anti-CD40L treatment in systemic lupus erythematosus patients

The CD40-CD40L system has pleiotropic effects in a variety of cells and biological processes including immune response, thrombosis and atherogenesis. Within the immune system, these molecules represent a critical link between its humoral and cellular arms. As a result of these attributes and based on preclinical data in animals, anti-CD40L antibodies were tested in a variety of immunologic diseases including idiopathic thrombocytopenic purpura, psoriasis, Crohn's disease, systemic lupus erythematosus and transplantation. Phase I/II studies in humans with lupus nephritis demonstrated reduction of anti-double-stranded DNA (anti-dsDNA) antibodies but not of protective antibodies. Reduction of anti-DNA was associated with increased serum complement levels and reduced glomerular inflammation. As a result of thrombotic effects, observed even in patients negative for anti-cardiolipin antibodies, there is a temporary halt on further human studies. The reasons for the prothrombotic effects are not clear at present but may represent effects on platelets and/or the endothelium. In view of the significant immunomodulatory effects of anti-CD40L treatment in patients with lupus nephritis, the increasing realization of the importance of premature atherosclerosis in lupus and an increasing amount of data supporting a role for the CD40-CD40L interactions in this process, inhibition of this pathway deserves further exploration in lupus.

Amelioration of autoimmune nephritis by imatinib in MRL/lpr mice

OBJECTIVE

To examine whether the platelet-derived growth factor (PDGF) receptor antagonist imatinib ameliorates glomerulonephritis in MRL/lpr mice, a condition that is similar to severe lupus nephritis in humans.

METHODS

Sixteen-week-old MRL/lpr female mice having an advanced stage of glomerulonephritis were divided into 3 groups according to treatment: 1) 50 mg/kg or 2) 10 mg/kg of imatinib (administered orally 4 times a week up to 24 weeks of age) or 3) vehicle solution (untreated group). The histopathologic condition of the kidneys and salivary glands of each mouse as well as the cumulative survival rates, extent of lymphadenopathy and splenomegaly, and serum chemistry and immunologic values were assessed.

RESULTS

In mice treated with 50 mg/kg imatinib, neither proliferation of glomerular cells nor crescent formation occurred. A drastic decrease in mesangial matrix was noted. Mice treated with 50 mg/kg imatinib had a prolonged life span compared with mice treated with 10 mg/kg imatinib and untreated mice. Expression of PDGF receptor and transforming growth factor beta messenger RNA in the kidneys was significantly reduced in the 50 mg/kg imatinib-treated mice compared with that in the 10 mg/kg imatinib-treated mice (P < 0.05) and the untreated mice (P < 0.01). Intriguingly, lymphadenopathy and salivary gland inflammation were also attenuated in imatinib-treated mice, in a dose-dependent manner. Serum levels of IgG and anti-double-stranded DNA antibodies were also reduced in the imatinib-treated mice.

CONCLUSION

These findings indicate that imatinib has a pleiotropic therapeutic effect, namely, the inhibition of PDGF signaling and immunosuppression, on the glomerulonephritis of MRL/lpr mice, which suggests a potential application of this drug in the treatment of human lupus nephritis.

Decreased Expression of the Ets Family Transcription Factor Fli-1 Markedly Prolongs Survival and Significantly Reduces Renal Disease in MRL/lpr Mice

Increased Fli-1 mRNA is present in PBLs from systemic lupus erythematosus patients, and transgenic overexpression of Fli-1 in normal mice leads to a lupus-like disease. We report in this study that MRL/lpr mice, an animal model of systemic lupus erythematosus, have increased splenic expression of Fli-1 protein compared with BALB/c mice. Using mice with targeted gene disruption, we examined the effect of reduced Fli-1 expression on disease development in MRL/lpr mice. Complete knockout of Fli-1 is lethal in utero. Fli-1 protein expression in heterozygous MRL/lpr (Fli-1(+/-)) mice was reduced by 50% compared with wild-type MRL/lpr (Fli-1(+/+)) mice. Fli-1(+/-) MRL/lpr mice had significantly decreased serum levels of total IgG and anti-dsDNA Abs as disease progressed. Fli-1(+/-) MRL/lpr mice had significantly increased splenic CD8(+) and naive T cells compared with Fli-1(+/+) MRL/lpr mice. Both in vivo and in vitro production of MCP-1 were significantly decreased in Fli-1(+/-) MRL/lpr mice. The Fli-1(+/-) mice had markedly decreased proteinuria and significantly lower pathologic renal scores. At 48 wk of age, survival was significantly increased in the Fli-1(+/-) MRL/lpr mice, as 100% of Fli-1(+/-) MRL/lpr mice were alive, in contrast to only 27% of Fli-1(+/+) mice. These findings indicate that Fli-1 expression is important in lupus-like disease development, and that modulation of Fli-1 expression profoundly decreases renal disease and improves survival in MRL/lpr mice.

Gene therapy for autoimmune diseases: quo vadis?

Biological therapies using antibodies and cytokines are becoming widespread for the treatment of chronic inflammatory autoimmune diseases. However, these treatments have several limitations - such as expense, the need for repeated injections and unwanted side-effects - that can be overcome by genetic delivery. This review summarizes the ingenuity, sophistication and variety of gene-therapy approaches that have been taken in the design of therapeutic molecules and vectors, the engineering of cells and the regulation of gene expression for the targeting of disease outcome. We focus our attention on multiple sclerosis, type 1 diabetes and rheumatoid arthritis.

Links between type I interferons and the genetic basis of disease in mouse lupus

Systemic lupus erythematosus (SLE), like other autoimmune diseases, is a complex genetic trait with contributions from both major histocompatibility complex (MHC) genes and multiple non-MHC genes. Most of the contributing genes have yet to be identified. Studies of mouse models of lupus have provided important insight into the immunopathogenesis of lupus-like IgG autoantibody production and lupus nephritis, and genetic analyses of these mice are helping to unravel the complex and heterogeneous genetic basis of disease. Recent studies in both human SLE and mouse models of lupus have emphasized a potential role of type I interferons (IFN-alpha/beta) in the initiation and perpetuation of disease. There is now increasing interest in genes that affect IFN-alpha/beta expression-activity and IFN-regulated target genes that may be involved in the disease process. One example is interferon-inducible gene 202 (Ifi202), which has been identified as a major candidate susceptibility gene in the New Zealand hybrid model of lupus. Studies suggest that increased expression of this transcription factor leads to lupus through inhibition of lymphocyte apoptosis, although its effects on immune function are extremely complex and have yet to be fully defined. This review will focus on the genetic basis of disease in mouse lupus with a special emphasis on those genetic contributions that may affect IFN-alpha/beta activity and those that may be target genes of IFN-alpha/beta action.

Inhibition of lupus by genetic alteration of the interferon-alpha/beta receptor

Type I interferons (IFN-alphabeta) are immunoregulatory cytokines that promote both innate and adaptive immune responses. Although they have been implicated in human SLE, recent studies in mice have helped solidify this connection. By using lupus-prone mice with knockout of the IFN-alphabeta receptor, we and others have documented that lack of IFN-alphabeta leads to a marked reduction in disease manifestations, including autoantibody production, target organ damage and mortality. Furthermore, IFN-alphabeta was found to potentially contribute to several levels of disease pathogenesis. These included the differentiation and activation of dendritic cells, the activation and proliferation of T cells, T cell survival and the activation and survival of autoantibody-producing B cells. These findings strongly support the targeting of IFN-alphabeta in SLE and suggest that definition of the specific pathways critical for disease induction will be important for optimal intervention.

Microarray analysis of interferon-regulated genes in SLE

Altered regulation of interferon-alpha (IFNalpha) in systemic lupus erythematosus (SLE) was first demonstrated nearly 25 years ago. However, only recently has due attention been directed towards the central role of this cytokine family in SLE. Several laboratories have used large-scale microarray technology to study global gene expression patterns in heterogeneous populations of peripheral blood cells from lupus patients and control subjects. The results of these studies demonstrate that IFN-regulated genes are among the most significantly overexpressed in SLE mononuclear cells. In view of the protean effects of IFNs on immune system function, increased activity of IFNs may account for many of the immune system alterations that characterize SLE and contribute to autoimmunity. Definition of the nature of the major IFNs, or other factors, that drive the IFN-regulated gene expression signature noted in SLE is an important area for investigation that may lead to new approaches to targeted therapy of SLE.

Deficiency of the cyclin kinase inhibitor p21(WAF-1/CIP-1) promotes apoptosis of activated/memory T cells and inhibits spontaneous systemic autoimmunity

A characteristic feature of systemic lupus erythematosus is the accumulation of activated/memory T and B cells. These G₀/G₁-arrested cells express high levels of cyclin-dependent kinase inhibitors such as p21, are resistant to proliferation and apoptosis, and produce large amounts of proinflammatory cytokines. Herein, we show that ablation of p21 in lupus-prone mice allows these cells to reenter the cell cycle and undergo apoptosis, leading to autoimmune disease reduction. Absence of p21 resulted in enhanced Fas/FasL-mediated activation-induced T cell death, increased activation of procaspases 8 and 3, and loss of mitochondrial transmembrane potential. Increased apoptosis was also associated with p53 up-regulation and a modest shift in the ratio of Bax/Bcl-2 toward the proapoptotic Bax. Proliferation and apoptosis of B cells were also increased in p21^−/− lupus mice. Thus, modulation of the cell cycle pathway may be a novel approach to reduce apoptosis-resistant pathogenic lymphocytes and to ameliorate systemic autoimmunity.

Interferon-α in systemic lupus erythematosus

PURPOSE OF REVIEW

To describe the lines of evidence supporting a significant role for interferon-alpha (IFNalpha) in the pathogenesis of systemic lupus erythematosus (SLE) and to propose potential mechanisms by which IFNalpha contributes to the autoimmunity and immune dysfunction of SLE.

RECENT FINDINGS

Long-standing data indicating elevated levels of IFNalpha in the circulation of patients with SLE have recently been supplemented by reports from clinical practice, gene expression data, analysis of patient cells studied ex vivo, and studies of mechanisms of induction of IFNalpha production to provide complementary data strongly supporting a pathogenic role for IFNalpha in SLE. Recombinant IFNalpha, when administered as a therapy to patients with malignancy or hepatitis infection, can induce SLE. IFNalpha-regulated genes are highly expressed in SLE peripheral blood cells compared with cells from control subjects. Functional alterations of SLE mononuclear cells have been attributed to effects of IFNalpha. In addition, immune complexes bearing lupus autoantibodies and RNA or DNA have been shown to induce IFNalpha production. Finally, progress in understanding the role of Toll-like receptors (TLR) in the activation of the innate immune response has suggested potential mechanisms by which adjuvant-like factors act through TLR to induce IFNalpha as well as effective processing of self-antigens, resulting in activation of an adaptive immune response directed against self, as well as cytokine-mediated immune dysfunction.

SUMMARY

Substantial evidence supports a significant role for IFNalpha in the pathogenesis of lupus. The IFNalpha pathway represents a promising target for therapeutic intervention in patients with SLE.

Synthetic CpG oligodeoxynucleotides accelerate the development of lupus nephritis during preactive phase in NZB x NZWF1 mice

The effect of synthetic CpG-oligodeoxynucleotides (CpG-ODN) on the development of lupus nephritis during preactive phase (within seven months of age) in autoimmune lupus NZB x NZWF1 (B/WF1) mice was examined. Treatment of CpG-ODN was started at the age of 2.75 months and continued until 6.25 months. Overt disease began at the age of six months and progressed linearly at the age of 6.75 months in CpG-ODN-treated, but not control ODN-treated (control) groups. Also compared to control group, CpG-ODN-treated mice exhibited a severe glomerulonephritis (GN), with prominent deposits of IgG2a and C3, which paralleled increased titre of IgG2a type anti-nuclear antibody in the blood. Among several cytokines (interleukin, IL-6, IL-4, IL-1alpha, IL-10, interferon-gamma and tumor necrosis factor-alpha) in blood, IL-6 production paralleled the development of lupus nephritis. The present study suggests that CpG-ODN may enhance IL-6 production. The role of IL-6 in the development of GN will be discussed.

Type I IFN Protects Against Murine Lupus

Both the type I (IFN-alpha beta) and type II (IFN-gamma) IFNs have been heavily implicated in the pathogenesis of systemic lupus erythematosus. To test the relative roles of these systems, congenic lupus-prone MRL/CD95(lpr/lpr) (MRL/lpr) mice lacking the type I IFN receptor (IFN-RI), type II IFN receptor (IFN-RII), or both, were derived. As expected, deficiency for IFN-RII protected MRL/lpr mice from the development of significant autoimmune-associated lymphadenopathy, autoantibodies, and renal disease. However, deficiency for the IFN-RI surprisingly worsened lymphoproliferation, autoantibody production, and end organ disease; animals doubly deficient for IFN-RI and IFN-RII developed an autoimmune phenotype intermediate between wild-type and IFN-RII-deficient animals, all correlating with an ability of type I IFN to suppress MRL B cell activation. Thus, type I IFNs protect against both the humoral and end organ autoimmune syndrome of MRL/lpr mice, independent of IFN-gamma. These findings warrant caution in the use of type I IFN antagonists in the treatment of autoimmune diseases and suggest further investigation into the interplay between the types I and II IFNs during the ontogeny of pathogenic autoantibodies.

Modulation of renal glomerular disease using remote delivery of adenoviral-encoded solubletype II TGF-beta receptor fusion molecule

BACKGROUND

Systemic adenoviral (Ad) gene therapy for renal disorders is largely hampered by the unique architecture of the kidney. Consequently, currently available Ad vectors are of only limited therapeutic utility in the context of glomerular and fibroproliferative renal diseases.

METHODS

The Ad vectors studied in the context of blocking renal fibrosis were AdTbeta-ExR and AdCATbeta-TR. AdTbeta-ExR encodes a chimeric soluble molecule comprising the entire ectodomain of the human type II TGF-beta receptor, genetically fused to the Fc fragment of the human IgG1 (sTbetaRII), while AdCATbeta-TR encodes only the dominant-negative truncated ectodomain of the human type II TGF-beta receptor. The biologic activity of the type II TGF-beta receptor was evaluated in vitro by its ability to inhibit cellular proliferation and in vivo in a unilateral ureter obstruction fibrosis model. Renal targeting with sTbetaRII was evaluated immunohistochemically after intramuscular (IM) delivery of AdTbeta-ExR. The renal antifibrotic effect of the Ad vectors was evaluated in a lupus murine model with both light and electron microscopy and urinalysis.

RESULTS

sTbetaRII was detected in the glomeruli after remote IM injection of AdTbeta-ExR, but not the control AdCATbeta-TR, indicating renal deposition of the heterologous soluble fusion protein after its expression in the muscle and secretion into the circulation. AdTbeta-ExR, but not AdCATbeta-TR, could transiently inhibit mesangial expansion, glomerular hypercellularity, proteinuria and cortical interstitial fibrosis in a murine lupus model. However, the autoimmune renal disease eventually surpassed the antifibrotic effect.

CONCLUSIONS

These results indicate the superiority of a soluble type II TGF-beta receptor over a dominant-negative, non-soluble type II TGF-beta receptor in the context of blocking renal fibrosis in murine models.

Aberration of CCR7 CD8 memory T cells from patients with systemic lupus erythematosus: an inducer of T helper type 2 bias of CD4 T cells

Chemokine receptors are important in the entry of leucocytes into the inflammatory sites of systemic lupus erythematosus (SLE). CCR7(+) and CCR7(-) memory T cells exert different functions in homing, cytokine production and cytotoxicity. To determine whether differential expression and functions of the CCR7 occur in SLE patients, we examined CCR3, CCR4, CCR5, CCR7 and CCR9 on CD4(+) and CD8(+) T cells from normal and SLE subjects. Flow cytometry, real-time quantitative reverse transcription polymerase chain reactions and Northern blotting were used to detect the expression of chemokine receptors and cytokines; a chemotaxis assay was used to detect their functions. CD4(+) T-cell stimulation with syngeneic CCR7(+) CD8(+) CD45RO(+) T cells and dendritic cells (including transwell chambers) was used to induce cytokine expression. We demonstrated that CCR7 was selectively, frequently and functionally expressed on CD8(+) (94.8%) but not on CD4(+) (16.1%) T cells from patients with active SLE, whereas this phenomenon was not seen in normal subjects and in those whose SLE was inactive. CCR7(+) CD8(+) CD45RO(+) memory T cells from patients with active SLE, themselves T helper type 2 (Th2) biased, were inducers of Th2 bias in CD4(+) T cells in a cell-cell contact manner in vitro, meanwhile, the cells from both normal subjects and those whose SLE was inactive drove CD4(+) T cells into a regulatory T-cell-derived cytokine pattern. Our findings might provide new clues to understanding the functions of CCR7(+) CD8(+) CD45RO(+)'central' memory T cells in autoimmune diseases (such as SLE). We suggest that in the case of active SLE, CCR7(+) central memory T cells were able to enter peripheral blood and inflammatory sites from secondary lymphoid organs, were continuously expressing CCR7, and interacted with dendritic cells and functioned as CCR7(-)'effector' memory T cells, which were described in normal humans.

Anti-monocyte chemoattractant protein-1 gene therapy attenuates pulmonary fibrosis in mice

Monocyte chemoattractant protein-1 (MCP-1) is a proinflammatory chemokine and may play an important role in the development of pulmonary fibrosis. We examined a new therapeutic strategy that comprises the transfection of the mutant MCP-1 gene into skeletal muscles as a biofactory for anti-MCP-1 therapy against bleomycin-induced pulmonary fibrosis in mice. Overexpression of the mutant MCP-1 gene at 10–14 days after intratracheal instillation of bleomycin resulted in decreased DNA damage, apoptosis, and pulmonary fibrosis at 14 days. However, overexpression of the mutant MCP-1 at 0–4 days after bleomycin instillation did not result in decreased pathological grade, DNA damage, or apoptosis at 7 and 14 days. Because, in this model, inflammatory cell infiltration begins at 3 days and is followed by interstitial fibrosis, it is likely that MCP-1 has an important role to play in the development of fibrogenesis but not in the development of early lung inflammation. This method does not require the use of viral vector or neutralizing antibody, and, as such, it is possible to avoid problems regarding the pathogenicity of the viral vector or immunocomplex. This new strategy may be a beneficial method of treating pulmonary fibrosis from the viewpoint of clinical application.

A novel method to assay proteins in blood plasma after intravenous injection of plasmid DNA

Gene therapy is expected to lead to new and useful methods to treat diseases. The development of assays to quantitate gene-therapy-derived proteins circulating in blood will be essential to investigate the effects and side effects of the introduced proteins. The purpose of this study is to evaluate whether a protein circulating at trace concentrations in blood can be measured by tagging a peptide corresponding to glucagon residues 19-29 onto its C-terminal end. We constructed plasmids encoding chimeric proteins and transferred them into rats by hydrodynamics-based delivery. When plasmids encoding human IL8-glucagon 19-29 chimeric protein were injected into rats to evaluate the accuracy of this method, there was a high correlation between chimeric proteins measured by an enzyme-linked immunosorbent assay for human IL8 and one by a radioimmunoassay for glucagon. Furthermore, when plasmids coding rat IFN gamma receptor IgG-Fc glucagon 19-29 chimeric protein were injected to evaluate the time course of chimeric proteins in blood plasma, we could calculate the concentrations in blood from 10 microl plasma samples using glucagon 19-29 tag as follows: 2815+/-2318 ng/ml after 4 hours (mean+/-s.D.), 6061+/-2789 ng/ml after 8 hours, 5752+/-2270 ng/ml after 12 hours, 2870+/-1062 ng/ml after one day, 1440+/-334 ng/ml after three days, 1120+/-433 ng/ml after seven days, and 281+/-162 ng/ml after 16 days. Blood sugar levels which might have been increased by glucagon did not increase even at peak chime- ric protein concentrations. These results demonstrate a useful and convenient method to assay gene therapy products circulating in blood using a glucagon 19-29 tagging vector.

Perspectives for gene therapy in renal diseases

Somatic cell gene therapy has made considerable progress last five years and has shown clear success in some clinical trials. In the field of nephrology, both the elucidation of pathophysiology of renal diseases and the development of gene transfer technique have become driving force for new therapy of incurable renal diseases, such as Alport syndrome and polycystic kidney disease. Gene therapy of renal cancer, although its application is limited to advanced cancer, is the front-runner of clinical application. Erythropoietin gene therapy has provided encouraging results for the treatment of anemia in uremic rats and recently progressed to the inducible one in response to hypoxia. Gene therapy for glomerulonephritis and renal fibrosis showed prominent impact on experimental models, although the safety must be confirmed for prolonged treatment. Transplant kidney is an ideal material for gene modification and induction of tolerance in the transplant kidney is an attractive challenge. Emerging techniques are becoming available such as stem cell technology and messenger RNA silencing strategies. We believe that the future of gene therapy research is exciting and promising and it holds an enormous potential for clinical application.

IL-12 gene therapy using an electrically mediated nonviral approach reduces metastatic growth of melanoma

Interleukin-12 (IL-12) has been evaluated in both preclinical and clinical immunotherapy protocols as a potential therapy for melanoma. However, delivery of IL-12 in the form of recombinant protein can result in severe toxicity, and gene therapy has had limited success against B16.F10 murine melanoma. This study investigated the therapeutic effect of delivering a plasmid encoding IL-12 followed by electroporation on primary and secondary tumors. Three treatments of intratumoral (i.t.) plasmid injection and electroporation resulted in 80% of mice with B16.F10 melanoma tumors being tumor free for >100 days (cure). The "cured animals" were resistant to challenge with B16 cells. In a separate experiment, B16 cells were injected on the opposite flank of the treated tumor on the day of treatment. Eighty-seven percent of control mice developed a distant tumor while only 43.8% of mice receiving two or three i.t. electroporation treatments developed a distant tumor. For examination of tumor development in the lungs, mice were injected intravenously with B16.F10 cells then treated with i.m. injections of plasmid with or without electroporation. Only 37.5% of mice receiving i.m. injections and electroporation developed nodules in the lungs compared to 87.5% of mice in the no-treatment group. The results show that administration of a plasmid encoding IL-12 with electroporation has a therapeutic effect on primary tumors as well as distant tumors and metastases.

Genomic absence of the gene encoding T cell receptor Vbeta7.2 is linked to the presence of autoantibodies in Sjögren's syndrome

OBJECTIVE

It is not yet known whether the absence of certain T cell receptor V(beta) (TCRBV) genes (e.g., due to genomic deletion) has functional significance. We examined this question in relation to a known 21.6-kb insertion/deletion-related polymorphism (IDRP) in the human BV locus.

METHODS

New polymerase chain reaction (PCR) genotyping methods were used. Monoclonal antibodies to TCRBV gene products were used to confirm the absence of the relevant proteins. Patients with Sjögren's syndrome (SS) or systemic lupus erythematosus (SLE) were compared with normal controls with regard to TCR genotypes and serologic profiles.

RESULTS

There are 3 known haplotypes (I, D1, D2) and 6 possible genotypes related to the 21.6-kb IDRP. Novel PCR-based methods were used to define these genotypes. In subjects with deleted/deleted (D/D) genotypes, T cells could not express V(beta)7.2 TCRs, as assayed with a new antibody specific for V(beta)7.2. This was the sole significant difference between subjects without the insertion and those with either 1 or 2 copies. Surprisingly, we found that the D/D genotype was associated with primary SS, but only when pathogenic autoantibodies were present.

CONCLUSION

These results suggest that T cells expressing TCRs with V(beta)7.2 are protective against a pathogenic immune response in SS. Thus, genomic polymorphism of TCR genes (along with the correct HLA alleles) determines whether T cells can direct a pathogenic autoimmune response.

Enhanced expression of interferon-inducible protein 10 associated with Th1 profiles of chemokine receptor in autoimmune pulmonary inflammation of MRL/lpr mice

MRL/Mp-lpr/lpr (MRL/lpr) mice spontaneously develop systemic lupus erythematosus (SLE)-like disease. The natural history of the pulmonary involvement and the underlying mechanism of leukocyte infiltration into the lungs of MRL/lpr mice and SLE patients remains elusive. We aimed to investigate the expression profiles of chemokines and chemokine receptors in the lung of the SLE-prone mouse. We examined the correlation between lung inflammation and expression of IP-10 (interferon-gamma-inducible protein 10), a CXC chemokine, and TARC (thymus- and activation-regulated chemokine), a CC chemokine, in MRL/lpr mice, MRL/Mp-+/+ (MRL/+) mice, and C57BL/6 (B6) control mice. The extent of cell infiltration in the lung was assessed histopathologically. Reverse transcriptase PCR showed up-regulation of IP-10 mRNA expression in the lungs (P < 0.05) of MRL/lpr mice, in comparison with MRL/+ or B6 mice. The increase paralleled increased expression of a specific IP-10 receptor, CXCR3, and correlated with the degree of infiltration of mononuclear lymphocytes. In contrast, lung expression of TARC and its specific receptor, CCR4, were suppressed in MRL/lpr mice. Immunohistology showed that macrophage-like cells were the likely source of IP-10. Flow cytometric analyses revealed that the CXCR3-expressing cells were mainly infiltrating CD4 T cells and macrophages, which correlated with the degree of mononuclear lymphocyte infiltration. Recent data suggest that Th1 cells and Th1-derived cytokines play an important role in the development of SLE-like disease in MRL/lpr mice. Our results suggest that IP-10 expression in the lung is involved, through CXCR3, in the pathogenesis of pulmonary inflammation associated with migration of Th1 cells.

Microarray analysis of gene expression in lupus

Recent advances in the study of global patterns of gene expression with the use of microarray technology, coupled with data analysis using sophisticated statistical algorithms, have provided new insights into pathogenic mechanisms of disease. Complementary and reproducible data from multiple laboratories have documented the feasibility of analysis of heterogeneous populations of peripheral blood mononuclear cells from patients with rheumatic diseases through use of this powerful technology. Although some patterns of gene expression, including increased expression of immune system cell surface activation molecules, confirm previous data obtained with other techniques, some novel genes that are differentially expressed have been identified. Most interesting is the dominant pattern of interferon-induced gene expression detected among blood mononuclear cells from patients with systemic lupus erythematosus and juvenile dermatomyositis. These data are consistent with longstanding observations indicating increased circulating interferon-alpha in the blood of patients with active lupus, but draw attention to the dominance of the interferon pathway in the hierarchy of gene expression pathways implicated in systemic autoimmunity.

Differential effects of interleukin-4 in peptide induced autoimmunity

BALB/c mice immunized with multimeric DWEYSVWLSN develop IgG1 anti-DNA antibodies and glomerular immunoglobulin deposits, leading us to investigate the role of IL-4 in this model of antigen induced lupus. Splenocytes from DWEYSVWLSN immunized mice secreted IL-4 but not gamma-interferon. Following peptide immunization, IgG1 anti-peptide and anti-DNA antibodies were significantly higher in IL-4 wild type mice, while IgM and IgG3 anti-DNA levels were significantly higher in IL-4 knockout mice. Titers of IgG anti-laminin and anti-histone, but not anti-Sm/RNP and anti-cardiolipin antibodies, were significantly higher in the IL-4 wild type group. Glomerular immunoglobulin deposition was substantially decreased in IL-4 knockout mice. We conclude that while IL-4 does not materially affect the generation of some autoantibody responses associated with peptide induced autoimmunity, IL-4 deficiency inhibits kidney immunoglobulin deposition. The effect of IL-4 on humoral autoimmunity in lupus is complex, and is dependent on genetic background, the antigenic trigger and stage of disease.

Intramuscular gene transfer of soluble B7.1/IgG(1) fusion cDNA induces potent antitumor immunity as an adjuvant for DNA vaccination

Soluble B7.1/IgG Fc fusion protein, which has costimulatory effects, is an effective molecular adjuvant in tumor immune therapy. Here, we describe a nonviral intramuscular (i.m.) gene transfer method to deliver this therapeutic protein. Gene transfer was greatly enhanced by electroporation and highly efficient production of this protein was achieved. Serum levels reached up to 1 microg/ml with considerable length of expression and without apparent systemic adverse effects. Lymphocytes from mice coinjected with soluble B7.1/IgG(1) and carcinoembryonic antigen (CEA)-encoding plasmids showed significantly elevated CEA-stimulated proliferation, cytokine production, and cytotoxic T-lymphocyte (CTL) activity. These mice gained significant protection against a CEA-positive transplanted tumor, in terms of reduced tumor incidence and growth. The effects were superior when soluble B7.1/IgG(1) was expressed as compared to membrane-bound wild-type B7.1. Notably, expression of soluble B7.1/IgG(1) alone did not induce any protection against tumor, confirming its primary role as a costimulatory molecule rather than a direct antitumor agent. The plasmid encoding B7.1/IgG(1) did not have to be injected at the same site as the antigen-encoding plasmid to exert its adjuvant effect, indicating that circulating protein was sufficient. Muscle histopathology revealed minimal damage to DNA-injected muscles. Importantly, we show that, after gene transfer, muscle tissue can produce this protein in large quantity to exert its immune costimulatory effect for cancer therapy and it would be otherwise difficult and expensive to maintain this high a level of recombinant protein.

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.

Using single-gene deletions to identify checkpoints in the progression of systemic autoimmunity

Systemic lupus erythematosus is a multigenic disorder of unknown etiology. To investigate the roles that specific genes play in lupus, we have examined the disease profiles in mice with single-gene deletions. In total, some 17 genes have been studied. Absence of certain genes, such as CD40L, CD28, or Igh6, abrogated induction of autoimmunity. Other genes, such as Igh5, IL-4, or ICAM-1, had little effect on the development of disease. Intermediate effects were observed in IL-6-deficient mice, while absence of beta2-microglobulin resulted in loss of hypergammaglobulinemia and IgG1 autoantibodies, but produced little change in anti-chromatin antibodies or glomerular deposits. The most interesting observations were obtained with genes related to the expression or function of interferon-gamma (IFN-gamma). Reductions in IFN-gamma levels in murine lupus are associated with reductions in both autoantibody levels and immune-complex- mediated pathology. Genes involved in up-regulation of IFN-gamma expression, such as IL-12, STAT-4, or ICE, did not significantly influence autoimmunity, whereas absence of IFN-gamma or IFN-gamma receptor led to greatly reduced autoantibody response and immunopathology. Absence of IRF-1, a gene ex-pressed in response to IFN-gamma, resulted in selective retention of anti-chromatin antibodies but little glomerular pathology. These studies suggest that the presence of a baseline level of IFN-gamma, rather than increased expression, is important for autoimmunity. Furthermore, as the IRF-1 knockout demonstrates, specific defects in signaling pathways and gene expression subsequent to IFN-gamma/IFN-gamma receptor interaction may influence only certain disease parameters. It has not escaped our attention that IFN-gamma influences the expression and function of other immunologically relevant genes, such as IL-4, IL-6, and beta2-microglobulin. Thus, these genes may be part of the downstream events following IFN-gamma/IFN-gamma receptor interaction that promote the development of autoimmunity.

IL-12 deficiency in MRL-Fas(lpr) mice delays nephritis and intrarenal IFN-gamma expression, and diminishes systemic pathology

Autoimmune disease in MRL-Fas(lpr) mice is characterized by fatal nephritis, systemic pathology, and autoantibodies, mimicking human lupus. We previously reported that 1) intrarenal IL-12 elicits nephritis by fostering the accumulation of intrarenal IFN-gamma-secreting T cells, and 2) MRL-Fas(lpr) mice deficient in the IFN-gamma receptor were spared from nephritis. Therefore, we hypothesized that eliminating IL-12 in MRL-Fas(lpr) mice reduces IFN-gamma-secreting cells and thereby prevents systemic pathology. For this purpose, we constructed an IL-12p40-deficient MRL-Fas(lpr)(IL-12(-/-)) strain. We determined that glomerular and interstitial, but not perivascular, renal pathology were decreased in IL-12(-/-) mice vs the wild-type (WT) strain (5 mo of age). Similarly, systemic pathology (lung, lacrimal and salivary glands, skin, and lymphadenopathy) was diminished. The intrarenal accumulation of T cells (CD4(+), CD8(+), CD4(-)CD8(-)B220(+)) and macrophages was dramatically reduced in IL-12(-/-) MRL-Fas(lpr) kidneys. We determined that there were fewer IFN-gamma transcripts (>70%) in the IL-12(-/-) protected kidneys compared with the WT kidneys. Similarly, cells propagated from IL-12(-/-) MRL-Fas(lpr) kidneys generated substantially less IFN-gamma when stimulated with IL-12 and IL-18 compared with those from WT kidneys, and we detected fewer CD8 and B220 T cells producing IFN-gamma in these IL-12(-/-) MRL-Fas(lpr) kidneys. Of note, survival was modestly extended in the IL-12(-/-) MRL-Fas(lpr) mice. While lung and lacrimal and salivary gland pathology remained reduced in moribund IL-12(-/-) MRL-Fas(lpr) mice, renal pathology and IFN-gamma expression were equivalent to those in the WT strain. Thus, we suggest that IL-12 is a therapeutic target for multiple tissues in lupus; however blocking IL-12 alone is not sufficient to confer enduring protection from lupus nephritis.

Type-I interferon receptor deficiency reduces lupus-like disease in NZB mice

Indirect evidence suggests that type-I interferons (IFN-alpha/beta) play a significant role in the pathogenesis of lupus. To directly examine the contribution of these pleiotropic molecules, we created congenic NZB mice lacking the alpha-chain of IFN-alpha/betaR, the common receptor for the multiple IFN-alpha/beta species. Compared with littermate controls, homozygous IFN-alpha/betaR-deleted NZB mice had significantly reduced anti-erythrocyte autoantibodies, erythroblastosis, hemolytic anemia, anti-DNA autoantibodies, kidney disease, and mortality. These reductions were intermediate in the heterozygous-deleted mice. The disease-ameliorating effects were accompanied by reductions in splenomegaly and in several immune cell subsets, including B-1 cells, the major producers of anti-erythrocyte autoantibodies. Decreases of B and T cell proliferation in vitro and in vivo, and of dendritic cell maturation and T cell stimulatory activity in vitro were also detected. Absence of signaling through the IFN-alpha/betaR, however, did not affect increased basal levels of the IFN-responsive p202 phosphoprotein, encoded by a polymorphic variant of the Ifi202 gene associated with the Nba2 predisposing locus in NZB mice. The data indicate that type-I IFNs are important mediators in the pathogenesis of murine lupus, and that reducing their activity in the human counterpart may be beneficial.

A short course of BG9588 (anti-CD40 ligand antibody) improves serologic activity and decreases hematuria in patients with proliferative lupus glomerulonephritis

OBJECTIVE

CD40-CD40 ligand (CD40L) interactions play a significant role in the production of autoantibodies and tissue injury in lupus nephritis. We performed an open-label, multiple-dose study to evaluate the safety, efficacy, and pharmacokinetics of BG9588, a humanized anti-CD40L antibody, in patients with proliferative lupus nephritis. The primary outcome measure was 50% reduction in proteinuria without worsening of renal function.

METHODS

Twenty-eight patients with active proliferative lupus nephritis were scheduled to receive 20 mg/kg of BG9588 at biweekly intervals for the first 3 doses and at monthly intervals for 4 additional doses. Safety evaluations were performed on all patients. Eighteen patients receiving at least 3 doses were evaluated for efficacy.

RESULTS

The study was terminated prematurely because of thromboembolic events occurring in patients in this and other BG9588 protocols (2 myocardial infarctions in this study). Of the 18 patients for whom efficacy could be evaluated, 2 had a 50% reduction in proteinuria without worsening of renal function. Mean reductions of 38.9% (P < 0.005), 50.1% (P < 0.005), and 25.3% (P < 0.05) in anti-double-stranded DNA (anti-dsDNA) antibody titers were observed at 1, 2, and 3 months, respectively, after the last treatment. There was a significant increase in serum C3 concentrations at 1 month after the last dose (P < 0.005), and hematuria disappeared in all 5 patients with significant hematuria at baseline. There were no statistically significant reductions in lymphocyte count or serum immunoglobulin, anticardiolipin antibody, or rubella IgG antibody concentrations after therapy.

CONCLUSION

A short course of BG9588 treatment in patients with proliferative lupus nephritis reduces anti-dsDNA antibodies, increases C3 concentrations, and decreases hematuria, suggesting that the drug has immunomodulatory action. Additional studies will be needed to evaluate its long-term effects.

Costimulatory molecule-targeted antibody therapy of a spontaneous autoimmune disease

Humans and mice deficient in Fas, a tumor necrosis factor (TNF)-receptor family member, cannot induce apoptosis of autoreactive cells, and consequently develop progressive lymphoproliferative disorders and lupus-like autoimmune diseases. Previous studies have shown that short-term administrations of agonistic monoclonal antibodies against CD137, another TNF-receptor family member, activate T cells and induce rejection of allografts and established tumors. Here we report that treatment with an agonistic monoclonal antibody to CD137 (2A) blocks lymphadenopathy and spontaneous autoimmune diseases in Fas-deficient MRL/lpr mice, ultimately leading to their prolonged survival. Notably, 2A treatment rapidly augments IFN-gamma production, and induces the depletion of autoreactive B cells and abnormal double-negative T cells, possibly by increasing their apoptosis through Fas- and TNF receptor-independent mechanisms. This study demonstrates that agonistic monoclonal antibodies specific for costimulatory molecules can be used as novel therapeutic agents to delete autoreactive lymphocytes and block autoimmune disease progression.