Inquiry into murine and human lupus

Murine models of systemic lupus erythematosus: B and T cell responses to spliceosomal ribonucleoproteins in MRL/Fas(lpr) and (NZB x NZW)F(1) lupus mice

(NZB x NZW)F(1) and MRL/Fas(lpr) lupus mice present a similar phenotype with a spectrum of autoantibodies associated with very severe nephritis. It is thought, however, that in contrast to other lupus-prone mice such as MRL/Fas(lpr) mice, (NZB x NZW)F(1) mice do not generate autoantibodies to ribonucleoproteins (RNP) Sm/RNP. In this study, we demonstrate that contrary to previous reports, the autoimmune response directed against Sm/RNP antigens also occurs in NZB x NZW mice. CD4(+) T cells from unprimed 10-week-old NZB x NZW mice proliferate and secrete IL-2 in response to peptide 131-151 of the U1-70K protein, which is known to contain a T(h) epitope recognized by CD4(+) T cells from MRL/Fas(lpr) mice. Peptide 131-151, which was found to bind I-A(k) and I-E(k) class II MHC molecules, also bound both I-A(d) and I-E(d) molecules. This result led us to also re-evaluate longitudinally the anti-Sm/RNP antibody response in NZB x NZW mice. We found that 25-week-old mice do produce antibodies reacting with several small nuclear and heterogeneous nuclear (hn) RNP proteins, such as SmD1, U1-70K and hnRNP A2/B1 proteins. The fine specificity of these antibodies was studied with overlapping synthetic peptides. The same antigenically positive and negative peptides were characterized in MRL/Fas(lpr) and NZB x NZW mice in the three proteins. This new finding can help to understand the mechanisms involved in the development of the anti-Sm/RNP antibody response and, particularly, the role played by non-MHC genes in this autoimmune response.

Predominance of Th1 immune response in diffuse proliferative lupus nephritis

OBJECTIVE

Lupus nephritis, which shows various histologic patterns, is a serious complication of systemic lupus erythematosus (SLE). We previously demonstrated the importance of Thl cell-mediated immune response in patients with diffuse proliferative lupus nephritis (DPLN). The aim of this study was to examine the relationship between the peripheral blood Th1/Th2 balance and the intrarenal immune response.

METHODS

The Th1:Th2 ratio in peripheral blood was measured by intracellular staining for cytokines with flow cytometry. Immunohistochemical analysis of renal biopsy specimens was performed to clarify the characterization of local infiltrating cells in 3 groups of subjects: SLE patients with World Health Organization (WHO) class IV nephritis (DPLN) (group I; n = 13), SLE patients with WHO class V nephritis (group II; n = 9), and patients with minor glomerular lesions (group III; n = 7). In addition, the histologic activity index and chronicity index were evaluated and correlated with the Th1:Th2 ratio.

RESULTS

Immunohistochemical studies showed higher numbers of CD68+ macrophages, CD3 + T cells, and interferon-gamma-positive cells in group I than in groups II or III. Renal tissues from patients in group I also showed up-regulation of expression of osteopontin and CD40, with a small number of infiltrating T cells expressing interleukin-4. Overall, the Thl:Th2 ratio in group I patients (SLE with DPLN) was high and correlated significantly with the histologic activity index, but not with the chronicity index.

CONCLUSION

We have identified a predominance of Thl-type response in both peripheral and renal tissues of patients with DPLN, suggesting that the peripheral blood Thl:Th2 ratio directly reflects the local histopathologic findings. In patients with lupus nephritis, the peripheral blood Th1:Th2 ratio could be useful as a parameter that reflects the renal histologic activity or the strength of the local Thl response.

Increased frequency of pre-germinal center B cells and plasma cell precursors in the blood of children with systemic lupus erythematosus

We have analyzed the blood B cell subpopulations of children with systemic lupus erythematosus (SLE) and healthy controls. We found that the normal recirculating mature B cell pool is composed of four subsets: conventional naive and memory B cells, a novel B cell subset with pregerminal center phenotype (IgD(+)CD38(+)centerin(+)), and a plasma cell precursor subset (CD20(-)CD19(+/low)CD27(+/++) CD38(++)). In SLE patients, naive and memory B cells (CD20(+)CD38(-)) are approximately 90% reduced, whereas oligoclonal plasma cell precursors are 3-fold expanded, independently of disease activity and modality of therapy. Pregerminal center cells in SLE are decreased to a lesser extent than conventional B cells, and therefore represent the predominant blood B cell subset in a number of patients. Thus, SLE is associated with major blood B cell subset alterations.

Lupus nephritis: lessons from experimental animal models

Lupus nephritis is a frequent and severe complication of SLE. In the last decades, animal models for SLE have been studied widely to investigate the immunopathology of this autoimmune disease because abnormalities can be studied and manipulated before clinical signs of the disease become apparent. In this review an overview is given of our current knowledge on the development of lupus nephritis, as derived from animal models, and a hypothetical pathway for the development of lupus nephritis is postulated. The relevance of the studies in experimental models in relationship with our knowledge of human SLE is discussed.

Elevation of proinflammatory cytokine (IL-18, IL-17, IL-12) and Th2 cytokine (IL-4) concentrations in patients with systemic lupus erythematosus

Previous studies have indicated that the autoimmune phenomenon might be caused by an imbalance of T helper cell (Th) cytokines. We measured the plasma concentrations of three novel proinflammatory cytokines interleukin (IL)-17, IL-18, IL-12 and a key Th2 cytokine IL-4 in patients with systemic lupus erythematosus (SLE) and correlated the ratio of proinflammatory/Th2 cytokines with SLE disease activity index (SLEDAI). Plasma IL-12, IL-17, IL-18 and IL-4 concentrations of 36 SLE patients and 18 sex- and age-matched control subjects were measured by enzyme linked immunosorbent assay. All were significantly higher in SLE patients than control subjects (IL-12, mean+/-s.d. of 166.7+/-84.5 vs 93.5+/-39.2 pg/ml, P<0.001; IL-17, 76.5+/-45.7 vs 37.6+/-35.3 pg/ml, P=0.002; IL-18, 368.7+/-199. 5 vs 141.1+/-47.1 pg/ml, P<0.001; and IL-4, 27.1+/-15.3 vs 17.3+/-7. 2 pg/ml, P<0.05), and IL-18/IL-4 ratio correlated positively and significantly with SLEDAI score (r=0.435, P=0.006). We propose that SLE is characterized by an elevation of both Th1 and Th2 cytokines: the elevation of proinflammatory cytokine IL-12, IL-17 and IL-18 may trigger the inflammatory process in SLE and the elevation of IL-18/IL-4 ratio suggests an imbalance of cytokine profile to mediate the inflammatory response.

IL-10 stimulates production of platelet-activating factor by monocytes of patients with active systemic lupus erythematosus (SLE)

IL-10 displays modulatory properties on the synthesis of platelet-activating factor (PAF), a potent inflammatory mediator of vascular injury. Despite the fact that IL-10 is considered to be an anti-inflammatory cytokine, IL-10 levels correlate with disease activity in SLE. Moreover, in SLE IL-10 is unable to exert its immunosuppressive and anti-inflammatory effects. We have investigated the ability of IL-10 to stimulate PAF production from monocytes of SLE patients. Spontaneous and IL-10-stimulated PAF production by peripheral blood monocytes was measured in active (n = 13) and inactive (n = 14) SLE patients and in 15 normal control subjects. We observed that monocytes derived from patients with active SLE, but not from controls or inactive SLE, spontaneously produced significant amounts of PAF. Moreover, IL-10 enhanced the synthesis of PAF from monocytes of active SLE patients only. IL-10-induced PAF production correlated with the severity of the disease and with the extent of proteinuria. These results indicate that IL-10 only stimulates the synthesis of PAF from monocytes of SLE patients when immunologically active, suggesting that IL-10 may possess a paradoxical proinflammatory effect in SLE by promoting the production of PAF, a secondary mediator of inflammation.

Measurement of intracellular interferon-gamma and interleukin-4 in whole blood T lymphocytes from patients with systemic lupus erythematosus

Contradictory data are available about the dominance of T-helper 1 (T(H)1), or T-helper 2 (T(H)2) cytokines in systemic lupus erythematosus (SLE). Therefore, intracellular interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) production of T lymphocytes was measured in whole blood of healthy donors and active and inactive SLE patients by flow cytometry. The percentage of IFN-gamma and IL-4 positive cells was low (<1%) in unstimulated samples of the healthy controls, while that of IFN-gamma and IL-4 positive cells in the stimulated cells was 25.2+/-10.6% and 0.6+/-1.5%, respectively. No significant difference was found between SLE patients and healthy controls and between active and inactive patients in these parameters either in the unstimulated or in the stimulated samples. One patient with severe disease had as high as 11.8% IL-4 positive cells and 12.5% IFN-gamma positive cells in the stimulated samples, but after the initiation of intensive corticosteroid and cytostatic therapy, the percentage of IL-4 positive T cells decreased (4.76%) while that of IFN-gamma positive T cells increased (47.91%). We conclude that the intracellular IL-4 and IFN-gamma expression of T lymphocytes does not differ markedly between SLE patients and healthy controls, with the possible exception of severe disease, when marked IL-4 overproduction may exist beside low IFN-gamma production. Furthermore, corticosteroid and cytostatic therapy might normalize this altered IFN-gamma/IL-4 ratio.

The immune system as a potential target for environmental estrogens (endocrine disrupters): a new emerging field

It is now well known that natural (17beta-estradiol) and synthetic (e.g. diethylstilbestrol) estrogens not only affect the reproductive system, but also markedly influence the immune system. Recently, a new class of estrogens that is abundant in the environment (in industrial chemicals, pesticides, and surfactants) has been recognized. Some of these estrogenic chemicals (which are a large subgroup of endocrine disrupters) have also been shown to influence the immune system. This review assimilates growing evidence in wildlife, laboratory animals and to a limited extent in humans, which suggests that environmental chemicals may also affect the immune system. Further studies are needed to ascertain the immunological consequences of exposure to environmental estrogens, especially in humans. At the present time, it is not known whether the human immune system responds to a low dose of environmental estrogens or if environmental estrogens influence certain subsets of human populations, rather than the general population. Conceivably, an alteration of the immune system by environmental estrogens could affect the individuals' ability to mount well-regulated immune responses to microbial and vaccine antigens, allergens, self and tumor antigens. Possible changes in the immune system must be investigated routinely in toxicity studies. A comprehensive mechanistic understanding of potential immunomodulatory chemicals is needed. In this regard, relevant laboratory animals may be especially useful in identifying susceptible periods of life, whether both genders are equally affected, in analysis of changes in target lymphoid organs, and to determine the immunological effects of mixtures of chemicals.

IL-12-encoding plasmid has a beneficial effect on spontaneous autoimmune disease in MRL/MP-lpr/lpr mice

Systemic lupus erythematosus (SLE) is characterized by immune abnormalities explained by the overproduction of Th(2)cytokines such as autoantibody production and polyclonal B cell activation. We examined the effect of administering a DNA plasmid encoding IL-12 on the lupus-like disease of MRL/MP-lpr/lpr (MRL/lpr) mice. Treatments were delivered intramuscularly every 4 weeks, starting at 4 weeks of age. This intervention significantly inhibited the accumulation of CD4(-)CD8(-)T cells, and reduced lymphadenopathy and splenomegaly. A significant decrease in serum IgG anti-DNA autoantibody titers was observed, and plasmid IL-12 therapy was also associated with a reduction in the proteinuria and glomerulonephritis characteristic of this disease. Serum IFN-gamma level was increased by inoculating IL-12 encoding plasmid, suggesting that the cytokine balance was skewed towards Th(1). The clinical implications of this suppression of autoimmune disease are also discussed.

Increased phosphoinositide 3-kinase activity induces a lymphoproliferative disorder and contributes to tumor generation in vivo

Alterations in the cell division:cell death ratio induce multiple autoimmune and transformation processes. Phosphoinositide 3-kinase (PI3K) controls cell division and cell death in vitro, but its effect on the function of the cellular immune system and on tumor formation in mammals is poorly characterized. Here we show that transgenic mice expressing in T lymphocytes an active form of PI3K derived from a thymic lymphoma, p65(PI3K), developed an infiltrating lymphoproliferative disorder and autoimmune renal disease with an increased number of T lymphocytes exhibiting a memory phenotype and reduced apoptosis. This pathology was strikingly similar to that described in mice exhibiting heterozygous loss of the tumor suppressor PTEN, a lipid and protein phosphatase. We show that overexpression of PTEN selectively blocks p65(PI3K)-induced 3T3 fibroblast transformation. Moreover, the early development of T cell lymphomas in p65(PI3K) Tg p53(-/-) mice indicated that PI3K contributes to tumor development. These observations demonstrate that constitutive activation of PI3K extends T cell survival in vivo, affects T cell homeostasis, and contributes to tumor generation, supporting a model in which selective increases in one type of PTEN substrate, the PI3K-derived lipid products, induce tumorigenesis. PI3K thus emerges as a potential target in autoimmune disease and cancer therapy.

Suppression of systemic lupus erythematosus disease in mice by oral administration of kidney extract

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the increased production of antibodies reactive with a variety of self and non-self antigens. A number of immunomodulatory therapies have been investigated for the disease process. Intragastric administration of low dose kidney extract (KE) three times weekly for 5 weeks and then weekly until 6 months of age in SLE mice, showed decreased anti-dsDNA antibody levels, less kidney damage and significantly prolonged survival compared with control phosphate buffered saline (PBS)-fed mice. The KE-fed mice also exhibited reduced T cell proliferative response to KE in comparison with PBS-fed controls. Serum isotype distribution of the anti-dsDNA antibodies revealed a marked reduction of IgG1 and IgG3 responses in the KE-fed mice. While the renal inflammatory cell infiltration and expression of interleukin-4 (IL-4) and IL-10 were markedly suppressed, no local enhancement of transforming growth factor-beta (TGF-beta) was detected. Oral administration of low dose KE, however, upregulated expression of IL-2, IFN-gamma and TNF-alpha in the kidneys and suppressed glomerulonephritis. These findings suggest that oral KE affects the disease process in SLE and raise the possibility that oral administration of KE or other potential autoantigens may provide a new approach for the treatment of SLE.

Impaired production of IL-12 in systemic lupus erythematosus. III: deficient IL-12 p40 gene expression and cross-regulation of IL-12, IL-10 and IFN-gamma gene expression

Interleukin 12 (IL-12) is a heterodimer comprising p35 and p40 subunits which are encoded and regulated separately. The authors previously demonstrated deficient IL-12 production in SLE which correlates negatively with disease activity. The present study was designed to determine whether deficiency of IL-12 and excess production of IL-10 and IL-6 in systemic lupus erythematosus (SLE) are due to aberrant regulation at the gene level. Using semiquantitative RT-PCR assay, it was shown that constitutive expression of IL-12 p35 gene is somewhat impaired in SLE compared with controls and that IL-12 p40 mRNA, which was present at low levels in controls, was undetectable in unstimulated SLE peripheral blood mononuclear cells (PBMC). Gene expression of IL-12 p35 and p40 was significantly increased in response to SAC, with significantly lower SAC-induced expression of p40 in SLE patients than controls. SAC-stimulated IL-12 p35 and p40 mRNAs were significantly augmented by interferon gamma (IFN-gamma). Exogenous IL-12 or IFN-gamma significantly inhibited IL-10 gene expression, without affecting IL-6 mRNA or other proinflammatory cytokine mRNA levels. These observations were further confirmed by studies of protein production at the single cell level using ELISPOT assay. Downregulation of IL-12 p40 expression appears to be the cause of IL12 p70 deficiency in SLE. If this defect could be repaired, normalization of IL-12 and IFN-gamma production should reduce excessive IL-10 and prevent pathology.

Th1/Th2 balance of peripheral T helper cells in systemic lupus erythematosus

OBJECTIVE

To analyze the Th1/Th2 balance of peripheral Th cells in patients with systemic lupus erythematosus (SLE).

METHODS

The Th1:Th2 ratio was analyzed in 3 groups: SLE without proteinuria (group I; n = 23), SLE with proteinuria (group II; n = 31), and normal controls (group III; n = 24). Group II patients who had undergone renal biopsy were classified into 3 subgroups based on their renal histopathologic findings. The intracellular cytokine detection method with flow cytometry was used to quantitate Th1 and Th2 cells.

RESULTS

There was no difference in the mean Th1:Th2 ratio between SLE patients (groups I and II) and healthy controls (group III). However, the mean value in group II was significantly higher than those in groups I and III. Moreover, within group II, the mean value in SLE patients who had diffuse proliferative lupus nephritis (World Health Organization class IV) was especially high.

CONCLUSION

Although SLE has been considered to be a disease in which Th2 cells predominate, the Th1/Th2 balance of peripheral Th cells in SLE patients in the present study did not show a predominance of these cells. In contrast, among SLE patients with WHO class IV lupus nephritis, there was a strong predominance of Th1.

High prevalence of T cell type I protein kinase A deficiency in systemic lupus erythematosus

OBJECTIVE

To estimate the prevalence of protein kinase A type I isozyme (PKA-I) deficiency in a cohort of systemic lupus erythematosus (SLE) patients, and to establish whether the isozyme deficiency is associated with SLE disease activity.

METHODS

Thirty-five SLE patients and 35 age-, sex-, and race-matched normal controls were studied. Fifteen subjects were restudied on at least 3 occasions over a 4-year interval. Clinical disease activity was estimated by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), and the T cell activation markers CD25+ and HLA-DR+ were quantified by flow cytometry. PKA-I isozyme activities were quantified in enriched T cells. Statistical analyses were performed by Student's t-test, Mann Whitney U test, and Pearson product moment test.

RESULTS

The mean PKA-I activity in SLE T cells (540 pmoles/minute/mg of protein) was significantly lower than that in control T cells (1,578 pmoles/ minute/mg of protein) (P<0.001). The prevalence of isozyme deficiency in this cohort was 80%. During a 4-year interval, PKA-I activities remained significantly reduced, whereas SLEDAI scores significantly improved. There was no relationship between deficient PKA-I activity and either SLEDAI scores or the proportion of T cells bearing CD25+ or HLA-DR+ activation markers.

CONCLUSION

There is a high prevalence of deficient T cell PKA-I isozyme activity in SLE that persists over time and is independent of SLE disease activity.

Antigen binding characteristics of experimentally-induced antibodies against hydroxyl radical modified native DNA

Hydroxyl radical, generated by UV irradiation of hydrogen peroxide caused damage to native calf thymus DNA leading to strand breaks, base modification and decrease in melting temperature. The ROS-DNA was highly immunogenic in goat. The antibody activity was inhibited to the extent of 89% with the immunogen as inhibitor. Antigenic specificity of anti-ROS-DNA antibodies by competition ELISA showed multiple cross-reactivity, recognizing B-, A- and allied conformations. The immune complex formation with native and ROS-DNA was substantiated by band shift assay. A striking observation, is the enhanced recognition of ROS-thymine and ROS-poly(dT) by the induced antibodies. These investigations suggest that ROS might be the plausible candidate for the presentation of unique epitopes on ROS-DNA, in particular of thymine, inducing antibodies cross-reacting with native DNA and play an important role in the pathogenesis of SLE.

Intrinsic Defects in Macrophage IL-12 Production Associated with Immune Dysfunction in the MRL/++ and New Zealand Black/White F1 Lupus-Prone Mice and the Leishmania major-Susceptible BALB/c Strain

We have demonstrated that macrophages (Mφ) from young, prediseased, lupus-prone MRL/++ and New Zealand Black/White F1 mice display defective production of TNF-α, IL-1, and IL-6, but normal production of IL-10. In an attempt to determine the potential functional implications of this phenotype for autoimmunity, we demonstrate here that endotoxin-activated Mφ from these lupus-prone mice showed dramatically reduced expression of IL-12, a cytokine essential for Th1 responses that may be defective during lupus. IL-12 production was also reduced by Mφ from the control BALB/c strain, compatible with the concept that a genetically programmed deficit in IL-12 levels may underlie the IL-4-dominated BALB/c response to infection by the parasite Leishmania major. Although both IL-12 and TNF-α expression defects by Mφ from lupus-prone strains are expressed rapidly after activation, treatment with each cytokine demonstrated that only TNF-α contributes to the subsequent dysregulation of Mφ IL-1 and IL-6 expression in these strains, and that the reduced autocrine activity of defective IL-12 or TNF-α levels was not causal to each other. Although the intrinsic defect in IL-12 expression by lupus-prone and BALB/c Mφ may lead to defective Th1 responses, these Mφ responded to the Th1-derived cytokine, IFN-γ, in a normal fashion suggesting a defective role in the induction, rather than the propagation, of Th1 responses in these mice. Our finding of a conserved intrinsic defect in IL-12 production by Mφ from the two principal mouse models of multigenic lupus provides insight into how excessive humoral responses may develop, and perhaps be prevented, in systemic autoimmune disease.

Linkage of a major quantitative trait locus to Yaa gene-induced lupus-like nephritis in (NZW x C57BL/6)F1 mice

In the present study, we mapped the major quantitative trait loci (QTL) differing between the NZW and C57BL/6 inbred strains of mice by making use of (NZW x C57BL/6.Yaa)F1 mice, a model in which the lupus-like autoimmune syndrome observed in male mice is associated with the presence of an as yet unidentified Y chromosome-linked autoimmune acceleration gene, Yaa. Linkage analysis of 126 C57BL/6 x (NZW x C57BL/6.Yaa)F1 backcross males provided evidence for a major QTL on chromosome 7 controlling both the severity of glomerulonephritis and the production of IgG anti-DNA autoantibody and retroviral gp70-anti-gp70 immune complexes. Two additional QTL of C57BL/6 origin on chromosome 17 had no apparent individual effects, but showed strong epistatic interaction with chromosome 7 QTL for disease severity and anti-DNA autoantibody production. Our data also identified on chromosome 13 a QTL of NZW origin with a major effect on the level of gp70, and showing an additive effect with the chromosome 7 QTL on the level of gp70 immune complexes. Our study thus provides a model to dissect the complex genetic interactions that result in manifestations of murine lupus-like disease.

Susceptibility to lupus nephritis in the NZB/W model system

Advances in genetic mapping have resulted in the identification of multiple lupus susceptibility loci in the NZB/W mouse model. The analysis of congenic strains carrying these loci is now providing functional data on their role in lupus pathogenesis and is paving the way to the identification of the susceptibility genes and their molecular characterization.

Lupus anticoagulants and antiphospholipid antibodies

In recent years, clinical syndromes involving lupus anticoagulants and antiphospholipid antibodies have come into increasing clinical prominence. Since the discovery that most antiphospholipid antibodies require the presence of anionic phospholipid-binding proteins such as B2-glycoprotein I and prothrombin, a large number of studies have attempted to delineate the specificity of these antibodies. Several mechanisms have been proposed to explain the hypercoagulable state associated with these antibodies. This review attempts to summarize these data and the challenges that confront efforts to delineate the pathogenesis of the prothrombotic state associated with the presence of these antibodies.

Effects of Bacterial DNA on Cytokine Production by (NZB/NZW)F1 Mice

Microbial DNA has multiple immune effects including the capacity to induce polyclonal B cell activation and cytokine production in normal mice. We recently described the accelerated induction of anti-DNA Abs in NZB/NZW mice immunized with Escherichia coli (EC) dsDNA; paradoxically these mice developed less renal disease than unimmunized mice or mice immunized with calf thymus DNA. We postulated that alterations in cytokine production induced by bacterial DNA may play a key role in renal protection. To determine the effect of bacterial DNA on cytokine production in NZB/NZW mice, we measured the serum cytokine levels, cell culture supernatant cytokine levels, and number of cytokine-producing splenocytes in NZB/NZW mice injected with EC DNA, calf thymus DNA, or an immune active oligonucleotide. There was a 10- to 25-fold increase in the number of cells secreting IFN-γ compared with IL-4 in mice immunized with EC DNA. IL-12-secreting cells were also increased by bacterial DNA immunization. In parallel with the increase in IFN-γ secreting cells, there was a significant rise in serum IFN-γ levels in mice receiving EC DNA. These results indicate that EC DNA modulates systemic cytokine levels in NZB/NZW mice, selectively increasing IL-12 and IFN-γ while decreasing IL-4 production. The cytokine response of NZB/NZW mice to bacterial DNA may be of significance in disease pathogenesis and relevant to the treatment of lupus-like disease.

Reactive oxygen species modified polyguanylic acid: immunogenicity and implications for systemic autoimmunity

The effect of the hydroxyl radical on polyguanylic acid [poly(G)] was investigated with regard to progressive increase of autoantibodies against it in systemic lupus erythematosus (SLE) and progressive systemic sclerosis (PSS). Rabbits immunized with both native and ROS-poly(G) induced high titre antibodies. Immune IgG exhibited a high degree of specificity towards the immunogen, reiterated visually by a gel retardation assay. The induced antibodies showed a wide range of cross-reactivity with various synthetic polynucleotides exhibiting B-, A-, and allied conformations. The specificity of induced antibodies resembled the diverse binding characteristics of lupus anti-DNA autoantibodies. Moreover, sera from scleroderma patients showed binding to native and ROS-poly(G). SLE and PSS autoantibodies showed preferential recognition of ROS-poly(G) over native poly(G). These results demonstrate that the hydroxyl modified guanine residues in DNA and RNA can induce circulating SLE and PSS autoantibodies.

DNAse treatment does not improve the survival of lupus prone (NZB x NZW)F1 mice

OBJECTIVE

To examine the efficacy of deoxyribonuclease I (DNAse) therapy in the (NZB x NZW)F1 murine model of lupus.

METHODS

Lupus-prone female (NZB x NZW)F1 mice were treated daily with 0-15 microg/g of recombinant DNAse for 1-6 months. Parameters including anti-DNA autoantibody production, activation of cytokine secreting cells, kidney function and longevity were monitored.

RESULTS

DNAse treatment selectively reduced the number of B cells secreting anti-dsDNA antibodies for approximately one month. However, neither short-term nor long-term treatment altered cytokine production, delayed the onset or reduced the severity of glomerulonephritis, or prolonged survival.

CONCLUSION

DNAse treatment initiated before, during, or after the onset of murine lupus did not improve clinical outcome.

Pathogenesis of autoimmunity in alphabeta T cell-deficient lupus-prone mice

Murine lupus in MRL mice has been strongly attributed to alphabeta T cell-dependent mechanisms. Non-alphabeta T cell-dependent mechanisms, such as gammadelta T cells, have been shown to drive antibody and autoantibody production, but they have not been considered capable of inducing end-organ disease. Here, we have expanded upon the findings of such previous work by examining the mechanism and extent of end-organ disease attainable via gammadelta T cells and/or non-alphabeta T cell-dependent mechanisms, assessing two prototypical lupus lesions, renal and skin disease, in TCR alpha -/- MRL mice that possessed either functional or defective Fas antigen (Fas + or lpr). Observed to 1 year of age, TCR alpha -/- MRL mice developed disease characterized by increased mortality, overt renal disease and skin lesions. While delayed in onset and/or reduced in severity compared with TCR alpha +/+ MRL/lpr animals, renal and skin lesions in alphabeta T cell-deficient animals were clearly increased in severity compared with age-matched control non-autoimmune mice. In contrast to TCR alpha +/+ MRL mice, whose disease reflected pan-isotype immune complex deposition with significant complement fixation, renal disease in TCR alpha -/- MRL animals reflected predominantly IgG1 immune complex deposition, with poor complement fixation. Thus, this study demonstrates conclusively that non-alphabeta T cell-dependent mechanisms can induce renal and skin injury in murine lupus, but at least in the kidney, only via humoral autoimmunity of a relatively non-pathological isotype which results in the delayed onset of end-organ damage.

Animal models for nervous system disease in systemic lupus erythematosus

Animal models have much to teach us about nervous system dysfunction in SLE. It should be stressed that the murine strains described in this review have variable expression in the onset and severity of clinical and serological features, perhaps making them more like a heterogeneous human population with SLE. With this in mind, studies involving animal models like those involving human subjects should use a sample size that ensures adequate power. It is not surprising that studies that use sample sizes as low as four to five animals per group would find discrepant results, especially in outcomes that are measured prior to the terminal phases of the disease. Similar to human SLE patients, murine models have systemic autoimmune as well as neurological manifestations. Studies with murine models must continue to consider some type of SLE disease activity measures in order to control for the effects of systemic disease on nervous system dysfunction. Because of the short time window between the earliest evidence of neurologic dysfunction and severe autoimmune disease manifestations, especially in MRL/lpr mice, the disease acceleration model may allow a more careful dissection of how immunological events are related to nervous system dysfunction. Alternatively, the study of MRL/lpr mice ultraearly (e.g., 3 weeks of age) could also provide invaluable information about the first events leading to nervous system dysfunction in SLE. Both approaches promise to identify predictors of specific nervous system manifestations that may suggest novel and more specific therapeutic interventions.

Interleukin-10 and interleukin-6 in lupus erythematosus and rheumatoid arthritis, correlations with acute phase proteins

We sought to investigate the influence of interleukin-10 (IL-10) and IL-6 on the acute phase proteins (APP) in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). IL-10, IL-6, Creactive protein (CRP), alpha-1-acid glycoprotein (AGP), and alpha1 antichymotrypsin (ACT) serum levels were determined in one hundred-eight patients (71 with SLE, 37 with RA). Quantification of the serum IL-10 level showed increased levels in SLE and RA patients as compared to healthy controls. Serum IL-6 level was found to be elevated in SLE and RA patients. A correlation between IL-10 and IL-6 serum level was found only in SLE. CRP and AGP serum levels were increased in RA as compared to controls, whereas in SLE only AGP was found elevated. A statistically significant correlation between IL-6 serum level and CRP, AGP and ACT was found only in RA. No correlation between IL-10 and serum level of CRP, AGP and ACT was established. Since IL-10 has a potent immunosuppressive activity, we expected it to be negatively correlated with APP levels. Surprisingly, IL-10 did not correlate with APP either in SLE or RA patients. However, the elevation of IL-10 serum levels in SLE and RA and the correlation between IL-10 and IL-6 in SLE may suggest that IL-10 may play a central role in inflammatory connective tissue diseases.

Roles of interferon-gamma and interleukin-4 in murine lupus

The systemic autoimmune syndrome of MRL/Mp-lpr/lpr (MRL/lpr) mice consists of severe pan-isotype hypergammaglobulinemia, autoantibody production, lymphadenopathy, and immune complex-associated end-organ disease. Its pathogenesis has been largely attributed to helper alphabeta T cells that may require critical cytokines to propagate pathogenic autoantibody production. To investigate the roles of prototypical Th1 and Th2 cytokines in the pathogenesis of murine lupus, IFN-gamma -/- and IL-4 -/- lupus-prone mice were generated by backcrossing cytokine knockout animals against MRL/lpr breeders. IFN-gamma -/- animals produced significantly reduced titers of IgG2a and IgG2b serum immunoglobulins as well as autoantibodies, but maintained comparable levels of IgG1 and IgE in comparison to cytokine-intact controls; in contrast, IL-4 -/- animals produced significantly less IgG1 and IgE serum immunoglobulins, but maintained comparable levels of IgG2a and IgG2b as well as autoantibodies in comparison to controls. Both IFN-gamma -/- and IL-4 -/- mice, however, developed significantly reduced lymphadenopathy and end-organ disease. These results suggest that IFN-gamma and IL-4 play opposing but dispensable roles in the development of lupus-associated hypergammaglobulinemia and autoantibody production; however, they both play prominent roles in the pathogenesis of murine lupus-associated tissue injury, as well as in lpr-induced lymphadenopathy.

Interleukin-4 protects against a genetically linked lupus-like autoimmune syndrome

Interleukin-4 (IL-4) provides support for humoral immune responses through upregulation of T helper (Th) type 2 cell differentiation, but it is not known whether IL-4 promotes antibody-mediated autoimmune diseases such as systemic lupus erythematosus (SLE). Here, we show that the constitutive expression of an IL-4 transgene by B cells completely prevents the development of lethal lupus-like glomerulonephritis in the (NZW x C57BL/6.Yaa)F1 murine model of SLE. This was associated with marked changes in the serum levels of IgG subclasses, rather than in the total levels of anti-DNA antibodies, with a lack of IgG3, a decrease of IgG2a, and an increase in IgG1 subclasses, and by a strong reduction in the serum levels of gp70-anti-gp70 immune complexes. This effect of the transgene appears to result from a modulation of the Th1 versus Th2 autoimmune response, since the protected mice displayed comparably modified IgG2a and IgG3 antibody response against exogenous T cell-dependent antigen, but not against T cell-independent antigens. Thus, IL-4 prevents the development of this lupus-like autoimmune disease, most likely by downregulating the appearance of Th1-mediated IgG subclasses of autoantibodies such as the IgG3 autoantibodies which have been shown to be especially nephritogenic.

Animal models of cutaneous lupus erythematosus and lupus erythematosus photosensitivity

Over the past decade, the most exciting and important finding in SLE-prone mice is the discovery of Fas/Fas ligand systems in the pathogenesis of autoimmune phenomena. A human model for murine lpr/gld disease has also been reported recently. Furthermore, as shown in Table 2, studies on Ig variable region genes, TCR genes and MHC class II genes have given us much information concerning human and murine SLE. With respect to cytokines, IL-2 deficiency and the key role of IL-6 have been found in SLE-prone mouse strains, and Th2 cytokine production has been demonstrated to play a more pathogenic role than Th1 cytokine production in human and murine SLE except for MRL/pr mice. TGF is also very intriguing because TGF-beta knockout mice show SLE-like autoantibodies and Sjögren syndrome-like lymphoproliferation. Apart from these basic scientific investigations, there are also many promising and practical therapeutic approaches. In particular, treatments with anti-CD4 antibody and murine CTLA4Ig which bound B7 and blocked binding of CD28 to B7 are outstanding. However, it remains obscure whether such new approaches are effective for the skin lesions of SLE-prone mice, although some immunosuppressive agents such as FK506, cyclosporin and Chinese herbal medicines have been evaluated to determine their selective effects on the skin lesions of MRL/lpr mice. Needless to say, mouse models are not identical, but similar, to human diseases. However, they are important in the search for the underlying pathogenesis of autoimmune diseases on the basis of careful evaluation of the similarities and differences between human diseases and these models. If such studies are steadily performed, then inbred or experimental models will become more promising tools for the investigation of cutaneous lupus erythematosus.