Dysregulation of T helper cell cytokines in autoimmune prone NZB x NZW F1 mice

PD-L1- and IL-4-expressing basophils promote pathogenic accumulation of T follicular helper cells in lupus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by anti-nuclear autoantibodies whose production is promoted by autoreactive T follicular helper (TFH) cells. During SLE pathogenesis, basophils accumulate in secondary lymphoid organs (SLO), amplify autoantibody production and disease progression through mechanisms that remain to be defined. Here, we provide evidence for a direct functional relationship between TFH cells and basophils during lupus pathogenesis, both in humans and mice. PD-L1 upregulation on basophils and IL-4 production are associated with TFH and TFH2 cell expansions and with disease activity. Pathogenic TFH cell accumulation, maintenance, and function in SLO were dependent on PD-L1 and IL-4 in basophils, which induced a transcriptional program allowing TFH2 cell differentiation and function. Our study establishes a direct mechanistic link between basophils and TFH cells in SLE that promotes autoantibody production and lupus nephritis.

Mouse models, antibodies, and neuroimaging: Current knowledge and future perspectives in neuropsychiatric systemic lupus erythematosus (NPSLE)

As a chronic autoimmune disease systemic lupus erythematosus (SLE) can also affect the central and the peripheral nervous system causing symptoms which are summed up as neuropsychiatric systemic lupus erythematosus (NPSLE). These symptoms are heterogenous including cognitive impairment, seizures, and fatigue, leading to morbidity or even mortality. At present, little is known about the pathophysiological processes involved in NPSLE. This review focuses on the current knowledge of the pathogenesis of NPSLE gained from the investigation of animal models, autoantibodies, and neuroimaging techniques. The antibodies investigated the most are anti-ribosomal P protein antibodies (Anti-rib P) and anti-N-Methyl-D-Aspartic Acid Receptor 2 antibodies (Anti-NR2), which represent a subpopulation of anti-dsDNA autoantibodies. Experimental data demonstrates that Anti-rib P and Anti-NR2 cause different neurological pathologies when applied intravenously (i.v.), intrathecally or intracerebrally in mice. Moreover, the investigation of lupus-prone mice, such as the MRL/MpJ-Faslpr/lpr strain (MRL/lpr) and the New Zealand black/New Zealand white mice (NZB × NZW F1) showed that circulating systemic antibodies cause different neuropsychiatric symptoms compared to intrathecally produced antibodies. Furthermore, neuroimaging techniques including magnetic resonance imaging (MRI) and positron emission tomography (PET) are commonly used tools to investigate structural and functional abnormalities in NPSLE patients. Current research suggests that the pathogenesis of NPSLE is heterogenous, complex and not yet fully understood. However, it demonstrates that further investigation is needed to develop individual therapy in NPSLE.

Transplantation of Adipose Tissue-Derived Mesenchymal Stem Cells Prevents the Development of Lupus Dermatitis

MRL/lpr mice spontaneously develop high titers of anti-dsDNA antibodies and symptoms such as glomerular nephritis and organ weight gain. They also develop spontaneous skin inflammation similar to the cutaneous lesions common in human lupus erythematosus. This study aimed to compare the effects of long-term serial administration of human adipose tissue-derived mesenchymal stem cells (ASCs), CTLA4Ig-overexpressing ASCs, and cyclophosphamide treatment in MRL/lpr mice. MRL/lpr mice were divided into saline (C), cyclophosphamide (Y), ASC early (E), ASC late (L), and CTLA4Ig-overexpressing ASC (CT) treatment groups. Background-matched control MRL/MPJ mice treated with saline (N) were also compared. The treatment period was 5-23 weeks, except for the L group (15-23 weeks). Blood and tissue samples were collected when the mice were 24 weeks old. Organ weight, anti-dsDNA antibodies, urine protein, skin and kidney histologic abnormalities, and trabecular bone volume were evaluated. The Y group showed the greatest decrease in anti-dsDNA antibodies, organ weight, degree of kidney inflammation and glomerular infiltration of C3, and incidence rate of severe proteinuria; the E, L, and CT treatment groups showed better results than the C group. ASC transplantation reduced anti-dsDNA antibody levels significantly. Mice treated with ASCs or CTLA4Ig-ASCs starting from the early disease stage did not show dermatitis upon gross examination; they demonstrated significant improvement in hyperkeratosis, acanthosis, and inflammatory cell infiltration scores in histopathology. Micro-CT analysis revealed that cyclophosphamide treatment significantly decreased bone volume and increased bone spacing in the trabecular bone. Thus, we found that ASC and CTLA4-ASC treatments prevent lupus dermatitis development in MRL/lpr mice without adverse effects.

A novel antagonist of Toll-like receptors 7, 8 and 9 suppresses lupus disease-associated parameters in NZBW/F1 mice

Systemic Lupus Erythematosus is an autoimmune disease characterized by production of autoantibodies against nucleic acid-associated antigens. Endogenous DNA and RNA associated with these antigens stimulate inflammatory responses through Toll-like receptors (TLRs) and exacerbate lupus disease pathology. We have evaluated an antagonist of TLR7, 8 and 9 as a therapeutic agent in lupus-prone NZBW/F1 mice. NZBW/F1 mice treated with the antagonist had lower serum levels of autoantibodies targeting DNA, RNP, Smith antigen, SSA and SSB than did untreated mice. Reduction in blood urea nitrogen and proteinuria and improvements in kidney histopathology were observed in antagonist-treated mice. The antagonist treatment also reduced serum IL-12 and IL-1β and increased IL-10 levels. Levels of mRNA for IL-6, iNOS and IL-1β were lower in the kidneys and spleen of antagonist-treated mice than in those of untreated mice. Levels of mRNA for IP-10, TNFRSF9 and FASL were lower and IL-4 mRNA were higher in spleens of antagonist-treated mice than in spleens of untreated mice. mRNA for the inflammasome component NLRP3 was lower and mRNA for the antioxidant enzymes, catalase and glutathione peroxidase 1 was higher in the kidneys of antagonist-treated mice than in those of untreated mice. These results show that the antagonist of TLR7, 8 and 9 effectively inhibits inflammatory pathways involved in the development of lupus in NZBW/F1 mice and constitutes a potential therapeutic approach for the treatment of lupus and other autoimmune diseases.

Accelerated pathological and clinical nephritis in systemic lupus erythematosus-prone New Zealand Mixed 2328 mice doubly deficient in TNF receptor 1 and TNF receptor 2 via a Th17-associated pathway

TNF-alpha has both proinflammatory and immunoregulatory functions. Whereas a protective role for TNF administration in systemic lupus erythematosus (SLE)-prone (New Zealand Black x New Zealand White)F(1) mice has been established, it remains uncertain whether this effect segregates at the individual TNFR. We generated SLE-prone New Zealand Mixed 2328 mice genetically deficient in TNFR1, in TNFR2, or in both receptors. Doubly-deficient mice developed accelerated pathological and clinical nephritis with elevated levels of circulating IgG anti-dsDNA autoantibodies and increased numbers of CD4(+) T lymphocytes, especially activated memory (CD44(high)CD62L(low)) CD4(+) T cells. We show that these cells expressed a Th17 gene profile, were positive for IL-17 intracellular staining by FACS, and produced exogenous IL-17 in culture. In contrast, immunological, pathological, and clinical profiles of mice deficient in either TNFR alone did not differ from those in each other or from those in wild-type controls. Thus, total ablation of TNF-alpha-mediated signaling was highly deleterious to the host in the New Zealand Mixed 2328 SLE model. These observations may have profound ramifications for the use of TNF and TNFR antagonists in human SLE and related autoimmune disorders, as well as demonstrate, for the first time, the association of the Th17 pathway with an animal model of SLE.

Enhanced Immune System Activation and Arterial Inflammation Accelerates Atherosclerosis in Lupus-Prone Mice

OBJECTIVE

Premature atherosclerosis is a characteristic feature of systemic lupus erythematosus, a prototypic autoimmune disease. The principle cellular and molecular mechanisms which underlie such accelerated atherosclerosis are indeterminate.

METHODS AND RESULTS

The pathophysiology of lupus-mediated atherogenesis was evaluated in a novel animal model involving transplantation of bone marrow cells from the lupus prone strain gld into Ldl-r(-/-) mice. Diet-induced atherogenesis in lethally-irradiated Ldl-r(-/-) mice transplanted with gld bone marrow cells resulted in accelerated atherosclerosis (+65%) as compared with control mice transplanted with wild-type marrow cells. Enhanced atherogenesis was associated with enhanced activation of both B and T lymphocytes and with arterial inflammation involving endothelial cell activation, monocyte recruitment, and accumulation of apoptotic debris, macrophages, and CD4 T cells, but was independent of plasma lipid levels and renal function.

CONCLUSIONS

Our data support the contention that despite the absence of both disturbed cholesterol homeostasis and renal dysfunction in autoimmune gld-->Ldl-r(-/-) mice, lupus disease induces enhanced activation of the immune system and acts locally on the vasculature to induce inflammation, together with accumulation of apoptotic debris, macrophages, and CD4 T cells, thereby accelerating plaque progression.

Maternal microchimerism leads to the presence of interleukin-2 in interleukin-2 knock out mice: implications for the role of interleukin-2 in thymic function

The role of interleukin-2 (IL-2) in thymic development is uncertain. Not surprisingly, IL-2 knockout (KO) mice have been used to address this question. However, as we report here, such mice are chimeric, containing both IL-2 KO cells and IL-2-expressing cells transferred in utero from their heterozygous mothers. These cells produce IL-2 in amounts detectable by conventional means, and their presence in lymphoid tissues confounds efforts to define the true IL-2 KO phenotype. To minimize the amount of IL-2 available to the thymus, we subjected recombinase activating gene-1 KO mice to bone marrow transplantation using IL-2 KO donors, and then followed the reconstitution of the thymus. The thymuses of these mice became increasingly aberrant over time, including abnormalities in both stromal cells and thymocytes. These results demonstrate that IL-2 is critical to several aspects of thymic function, a finding previously obscured by the presence of IL-2 in IL-2 KO mice.

T cell cytokine imbalance towards production of IFN-gamma and IL-10 in NZB/W F1 lupus-prone mice is associated with autoantibody levels and nephritis

OBJECTIVE

The role of T cell-derived cytokine production in lupus is poorly understood. We analysed the cytokine production of CD4(+) T cells in the NZB/W F1 mouse strain, the mouse model probably most closely resembling human systemic lupus erythematosus (SLE), and assessed whether a possible shift in the cytokines expressed is associated with age or disease activity.

METHODS

We used intracellular cytokine staining and flow cytometry to determine the cytokine expression of splenic CD4(+) T cells for interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), interleukin-4 (IL-4) and IL-10. NZB/W F1 mice at different ages spanning 5 to 36 weeks were analysed, healthy Balb/cxNZW F1 (CWF1) mice were used as controls. Serum anti-double-stranded DNA (anti-dsDNA) antibody levels were determined by enzyme-linked immunosorbent assay (ELISA), and proteinuria and plasma creatinine were estimated using commercial test kits.

RESULTS

The cytokine profile of CD4(+) T cells was shifted towards T-helper 1 (Th1) cells and the frequencies of Th cells expressing IFN-gamma(+) correlated with age, anti-dsDNA-immunoglobulin G (IgG) titre and proteinuria. An increased percentage of IL-10 producers correlated positively with anti-dsDNA-IgG and proteinuria, and a small gain in IL-4 producers correlated with plasma creatinine. Neither the percentage of IL-10 producers nor IL-4 producers showed a significant correlation with age. There was no significant change observed in the frequency of TNF-alpha T cells. The IFN-gamma/IL-4 ratio demonstrated an increasing shift towards a Th1-type response during disease development that was not present in healthy mouse strains.

CONCLUSION

The association between the frequencies of T cells expressing IFN-gamma and IL-10 and clinical findings suggests a key role for these cells in the pathogenesis of lupus.

Autoreactive responses to environmental factors: 3. Mouse strain-specific differences in induction and regulation of anti-DNA antibody responses due to phthalate-isomers

Little is known of the role of specific environmental factors in promoting autoimmune disorders such as systemic lupus erythematosus (SLE). This study addresses how exposure to phthalates, common environmental factors in foods, and biomedical devices could affect the immune functions of resistant and autoimmune-prone mice. We have previously shown that immunization with ortho-phthalate evokes anti-DNA antibody in BALB/c and NZB/W F1 mice, but only the latter suffer from nephritis and high mortality. BALB/c mice, in contrast, develop idiotype-specific CD8+ suppressor T cells downregulating autoreactive B cells. Here we report that all phthalate-isomers (ortho-, meta- and para-) are capable of inducing anti-DNA antibody responses and SLE-like syndromes. Kidney pathology worsens in NZB/W F1 and to a degree, in C57BL/6 mice after repeated exposure to phthalates. Only BALB/c and DBA/2 overcome adverse autoreactivity by induction of Ts cells; but in vivo depletion of these T cells renders these strains susceptible to autoreactivity. Anti-DNA antibodies in affected NZB/W F1 are largely IgG2a-type, while in BALB/c, DBA/2, and C57BL/6 mice IgG1-type. This is further corroborated by cytokine analyses that imply corresponding Th1/Th2 involvement. In summary, the commonly used phthalates appear harmful to susceptible strains, while BALB/c and DBA/2 are spared due to induction of Ts cells.

Distinct mechanisms of action of anti-CD154 in early versus late treatment of murine lupus nephritis

OBJECTIVE

Treatment with anti-CD154 antibody is known to ameliorate murine lupus nephritis when given early in the disease. The aims of this study were to identify the mechanism of this early effect, to determine whether late anti-CD154 treatment could halt established nephritis, and, if so, to examine potential mechanisms of late efficacy.

METHODS

We studied the effects of anti-CD154 treatment on autoantibody production and immune complex deposition, renal pathology, survival, and renal cytokine and chemokine messenger RNA (mRNA) expression both in (NZB x NZW)F(1) mice (BW mice) and in NZM.2410 mice.

RESULTS

Early treatment with anti-CD154 produced long-term survival in BW mice, with abrogation of renal immune complex deposition for months after treatment was stopped. Late anti-CD154 treatment, started after development of nephritis, could halt disease in approximately 40% of mice. In some mice, proteinuria could be reversed repeatedly with sequential courses of anti-CD154 antibody. The remissions induced by late treatment with anti-CD154 occurred despite ongoing renal immune complex deposition. In preliminary studies, responding mice had rapid reductions in renal mRNA for transforming growth factor beta, interleukin-10, and tumor necrosis factor alpha.

CONCLUSION

Amelioration of murine lupus by anti-CD154 therapy is mediated by distinct mechanisms in early versus late intervention. We postulate that anti-CD154 therapy prevents autoantibody production and renal immune complex deposition in the early, induction phase and limits secondary tissue damage in situ in the late, effector phase. These data demonstrate that CD40-CD154 interactions are critical for the maintenance of autoimmunity and suggest a potential role for anti-CD154 as a therapeutic agent in established human lupus.

Pivotal role of Stat4 and Stat6 in the pathogenesis of the lupus-like disease in the New Zealand mixed 2328 mice

We have developed novel genetically lupus-prone (NZB x NZW)F(1)-derived congenic New Zealand mixed (NZM) 2328 lines, which are either Stat4- or Stat6-deficient. Our studies show that the deficiency of Stat4 and Stat6 significantly alters the phenotype of the lupus-like disease in NZM 2328 congenic mice. Specifically, Stat4-deficient NZM mice develop accelerated nephritis and increased mortality in the absence of high levels of autoantibodies including anti-dsDNA Abs, and in the presence of relatively reduced levels of IFN-gamma. In contrast, Stat6-deficient NZM mice display a significant reduction in incidence of kidney disease, with a dramatic increase in survival, despite the presence of high levels of anti-dsDNA Abs. The lack of correlation between levels of these autoantibodies and kidney disease raises the question of the direct cause-effect relationships between the presence of autoantibodies and kidney disease. Furthermore, these results also question the apparent equation of the effect of Stat deficiency with loss of secretion or response to particular cytokines.

IL-4 and many roads to lupuslike autoimmunity

Interleukin-4 (IL-4) is a multifunctional cytokine. Although most studies have focused on the B-cell stimulatory and Th2 promoting properties of IL-4 in the development of autoantibodies and autoantibody-mediated diseases, a few reports suggest a T-cell suppressor role for this cytokine in lupus. Since these properties of IL-4 may sometimes result in opposing outcomes, amplifying or inhibitory, on overall B-cell functions, it is not surprising that a few studies have found no role for IL-4 in the development of autoantibodies and lupus. Evidence for a more novel role for IL-4 in the development of lupus nephritis comes from recent studies, which suggests that IL-4 may directly promote extracellular matrix deposition in the glomeruli. Consistent with this idea, blockade of IL-4 by antibody treatment or of its signaling by inactivation of the Stat6 gene ameliorates glomerulosclerosis and delays or even prevents the development of end-stage renal disease, despite the presence of high levels of IgG anti-dsDNA Antibodies. Thus, IL-4 may serve multiple roles in the development of lupus: it may enhance autoantibody production via its direct B-cell effects, protect against autoimmunity via its T-cell suppressor effect, or perpetuate tissue damage via its direct effects on target organs.

Differential contribution of IL-4 and STAT6 vs STAT4 to the development of lupus nephritis

Mechanisms that initiate lupus nephritis and cause progression to end-stage renal disease remain poorly understood. In this study, we show that lupus-prone New Zealand Mixed 2410 mice that develop a severe glomerulosclerosis and rapidly progressive renal disease overexpress IL-4 in vivo. In these mice, STAT6 deficiency or anti-IL-4 Ab treatment decreases type 2 cytokine responses and ameliorates kidney disease, particularly glomerulosclerosis, despite the presence of high levels of IgG anti-dsDNA Abs. STAT4 deficiency, however, decreases type 1 and increases type 2 cytokine responses, and accelerates nephritis, in the absence of high levels of IgG anti-dsDNA Abs. Thus, STAT6 and IL-4 may selectively contribute to the development of glomerulosclerosis, whereas STAT4 may play a role in autoantibody production.

Attenuation of autoimmune disease in Fas-deficient mice by treatment with a cytotoxic benzodiazepine

OBJECTIVE

Elimination of autoreactive cells relies on Fas-dependent activation-induced cell death mechanisms, an important component of peripheral tolerance. Defects in Fas or its cognate ligand lead to inefficient activation-induced cell death and are specific causes of lymphoproliferative and autoimmune diseases. The present study was undertaken to investigate a novel 1,4-benzodiazepine (Bz-423) that induces apoptosis and limits autoimmune disease in NZB/NZW mice, to determine its activity against lupus-like disease associated with defective Fas expression. We investigated the Fas-dependence of its cytotoxic actions, its therapeutic potential in mice deficient in Fas, and its therapeutic mechanism of action.

METHODS

Primary lymphocytes isolated from Fas-deficient MRL/MpJ-Fas(lpr) (MRL-lpr) mice were tested for sensitivity to Bz-423. Bz-423 was administered to MRL-lpr mice for short (1-week) or long (14-week) periods, and its effects on cell survival were determined along with measures of nephritis, arthritis, antibody titers, and Th subpopulations. BALB/c mice were similarly treated to determine if Bz-423 alters normal immune functions in vivo.

RESULTS

Administration of Bz-423 to MRL-lpr mice significantly reduced autoimmune disease including glomerulonephritis and arthritis. Treatment was associated with decreases in CD4+ T cells and an alteration in the Th1/Th2 balance. At the therapeutic dosage, Bz-423 did not interfere with normal T and B cell responses in BALB/c mice, suggesting that this agent is not globally immunosuppressive.

CONCLUSION

Bz-423 is a novel immunomodulatory agent that is active against disease even in the context of defective Fas signaling. It is a leading compound for further investigation into the development of selective therapies for lupus.

In vivo tolerance breakdown with dendritic cells pulsed with U1A protein in non-autoimmune mice: the induction of a high level of autoantibodies but not renal pathological changes

One of the hallmarks of systemic autoimmune diseases, such as systemic lupus erythematosus (SLE), is the immune response to nuclear autoantigens. Several studies have proposed that dendritic cells may acquire the nuclear autoantigens from the apoptotic cells to initiate the systemic autoimmune responses. To examine the immune response to a nuclear autoantigen induced by dendritic cells, bone marrow-derived dendritic cells (BMDCs) pulsed with U1 small nuclear ribonucleoprotein (snRNP)-A protein (U1A) were intravenously injected into non-autoimmune mice. The results showed that BMDCs pulsed with U1A proteins by intravenous injection into BALB/c (H-2d) and DBA-2xNZW F1 (H-2d/u) mice were capable of activating the autoreactive T cells and inducing a high titre of immunoglobulin G (IgG) anti-U1A antibodies. Both groups of mice with a high anti-U1A autoantibody titre also transiently developed IgG against double-stranded (ds) DNA. However, unlike NZBxNZW F1 (BWF1) (H-2d/u) mice, no obviously histopathological changes to the glomeruli were noted in the mice treated either with BMDCs or with U1A-pulsed BMDCs. Several months after immunization, all mice treated with U1A-pulsed BMDCs did develop IgG, but not the complement C3 deposit in the glomeruli. The cytokine profile produced by the U1A-specific T cells of primed DBA-2xNZW F1 mice was skewed toward the T helper type 1 phenotype compared with that of BWF1 mice. The model we describe here adds to the further understanding of the pathogenic mechanisms, such as self-antigen shifting, and the mechanisms that account for the different responses to self-antigens when in a normal or an autoimmune state.

Promotion of lupus in NZB x NZWF1 mice by plasmids encoding interferon (IFN)-gamma but not by those encoding interleukin (IL)-4

The present study extended our previous observation that interferon (IFN)-gamma may be responsible for the active disease that develops in NZB x NZWF1 mice and serves as a model for human systemic lupus erythematosus. Treatments with cytokine-encoding plasmids were delivered intraperitoneally every 4 weeks, starting at 3 months of age (i.e. before the onset of lupus). In comparison with the control plasmid and the IL-4-encoding plasmid, the IFN-gamma-encoding plasmid promoted increased blood urea nitrogen values and reduced the survival rate, and these changes were accompanied by the development of anti-nuclear antibody. There were no differences, however, between treatment with control plasmids and treatment with IL-4-encoding plasmids in terms of the development of lupus. The findings clearly indicated that IFN-gamma but not IL-4 contributed to the development of lupus in the NZB x NZWF1 mice.

T-cell antigenic determinants within hepatitis C virus nonstructural protein 3 and cytokine production profiles in hepatitis C

The aim of this study was to further investigate the role of T-helper cells in hepatitis C virus (HCV) infection, focusing on the T-cell antigenic determinants and cytokine profiles of nonstructural 3 (NS3) protein-stimulated peripheral blood mononuclear cells (PBMCs) of HCV patients. A total of 12 recombinant proteins of theNS3 region were purified and used to test T-cell proliferative response and antigenic determinants of HCV-seropositive patients. In addition, cytokines produced by antigen stimulated PBMCs were measured. Our data showed that PBMCs from 55.7% (34/61) of HCV patients proliferated to at least one antigen, but PBMCs of HCV seronegative patients did not. In addition, PBMCs from about 82.0% (32/39) HCV-seropositive patients produced significant amounts of cytokines (10 pg/mL). Interestingly, PBMCs from 66% of patients produced TH2-related cytokines such as interleukin (IL)-4 and IL-5. In mappingexperiments, the data showed multiple T-cell antigenic determinants. Our data demonstrated that NS3 antigen-stimulated PBMCs of HCV patients recognized multiple T-cell antigenic determinants and produced significant amounts of TH0 or TH2-related cytokines, which might play a critical role in the chronicity of HCV infection.

Unique therapeutic effects of the Japanese-Chinese herbal medicine, Sairei-to, on Th1/Th2 cytokines balance of the autoimmunity of MRL/lpr mice

Sairei-to, one of the Japanese-Chinese herbal medicines has been used for the treatment of various diseases, especially collagen disease and edema in nephrotic syndrome. However, the mechanism of the therapeutic effects remains uncertain. Therefore, we investigated the immunological changes of skin, kidney, spleen cells and serum in autoimmune-prone MRL/lpr, MRL/n and C57BL/6J mice treated with Sairei-to. In MRL/lpr mice treated with Sairei-to, the improvement of proteinuria, reduction in the number of hematoxylin bodies in kidney, and reduced serum levels of blood urea nitrogen were observed. These results indicate that Sairei-to can improve or inhibit the progression of lupus nephritis. The proportion of CD19 and the serum levels of IgG1, which is one of the pathogenesis of lupus dermatoses and lupus nephritis, were significantly reduced in Sairei-to-treated MRL/lpr mice. Therefore, it is suspected that the B cell function was suppressed by Sairei-to. In addition, CD4/8 ratio in spleen cells and the degree of lymphoproliferation in MRL/lpr mice also decreased. Interestingly, IL-4 producing spleen cells were increased significantly by ELISPOT assay, and IFN-gamma mRNA expressions were reduced in Sairei-to-treated MRL/lpr mice. Regarding the Th balance, an imbalance towards Th1 predominance may play a significant role in MRL/lpr mice, and the Th1 axis was suppressed and the Th2 axis became predominant in Sairei-to-treated MRL/lpr mice. On the other hand, Th2 cell type immunoglobulins (IgG1) were suppressed. These results suggested that Sairei-to is potential for impairing shifted Th1/Th2 balance and hypergammaglobulinemia resulting in therapeutic effects.

Reduction of serum interferon (IFN)-gamma concentration and lupus development in NZBxNZWF(1)mice by lactic dehydrogenase virus infection

The complexity of cytokine regulation and the imbalance of helper T (Th)1 and Th2 subsets in systemic lupus erythematosus (SLE) animal models and human SLE are well recognized. In this study in NZBxNZWF(1)mice, the effects of lactic dehydrogenase virus (LDV) infection on the production of interferon (IFN)-gamma in the serum and the development of autoimmune disease were examined. The progress of the disease (the development of glomerulonephritis, formation of glomerular IgG and C3 deposits, increase in the blood urea nitrogen values, and mortality) was parallel with an increase in serum IFN-gamma in uninfected NZBxNZWF(1)mice. These changes were inhibited in LDV-infected NZBxNZWF(1)mice. Our findings suggest that increase in serum IFN-gamma may be associated with the active disease in NZBxNZWF(1)mice.

The effect of cytokines on the activation-induced apoptosis of B cells in autoimmune NZB x NZW F1 mice

Programmed cell death (apoptosis) is an essential process in the development of various tissues and its involvement has been proposed for the elimination of self-reactive immature T and B lymphocytes when self antigens are first encountered. In order to further investigate the role of apoptosis in the pathogenesis of autoimmune disease, the apoptosis of lipopolysaccharide (LPS)-activated B cells, peritoneal cells from NZB x NZW F1 (NZB/W F1) mice and nonautoimmune BALB/c mice were assayed using an in vitro culture system. Splenic B cells were isolated and then stimulated with LPS before further activated with crosslinking antimu antibody. In addition, the apoptosis of peritoneal cells induced by crosslinking antimu antibody was also analyzed. The data revealed that the specific apoptosis of both activated B cells and peritoneal cells induced by crosslinking antimu antibody was very similar comparing NZB/W F1 and nonautoimmune BALB/c mice. This activation-induced B-cells apoptosis could be rescued, however, with the addition of cytokines such as interleukin (IL)-5 or IL-10, to the culture. The results suggest that there is no endogenous defect in the apoptosis of activated B cells for autoimmune NZB/W F1 comparing nonautoimmune BALB/c mice. Notably, however, abnormally high levels of the type 2 T helper (Th2)-related cytokines such as IL-5 or IL-10 may play an important role in the abnormal expansion of activated B cells in autoimmune NZB/W F1 mice.

The pathogenesis of autoimmunity in New Zealand mice

OBJECTIVE

New Zealand mice were the first spontaneous animal model of human systemic lupus erythematosus (SLE). Since their initial discovery in 1959, studies of these mice have provided insights into the immunopathogenesis and genetics of lupus and have had a substantial impact on our understanding of autoimmunity.

METHODS

We extensively reviewed published data for the past 40 years, including work in cellular immunology and molecular biology, to provide new information on the role of lymphoid subpopulations, cytokines, costimulatory molecules, apoptosis, and genetic susceptibility in the natural history of immunopathology in murine lupus.

RESULTS

Genetic factors constitute the most important contribution to autoimmunity in New Zealand mice, and specific major susceptibility loci have been described. In addition, there is evidence for a pluripotent stem cell defect, which has implications for developmental and functional defects of T and B cells. The end result of these defects is a breakdown of self-tolerance and production of autoantibodies. Further studies will undoubtedly shape our understanding of this murine model and provide the basis for novel diagnostic and therapeutic approaches in humans.

CONCLUSIONS

The advent of molecular biology, including the use of monoclonal antibody therapy in New Zealand mice, has been instrumental in our understanding of the loss of self-tolerance in SLE. Finally, identification of genetic susceptibility loci in the murine system has also led to important comparable studies in humans with SLE.

RELEVANCE

The observations in New Zealand mice are of particular importance to systemic lupus erythematosus (SLE).

Tamoxifen alleviates disease severity and decreases double negative T cells in autoimmune MRL-lpr/lpr mice

Previous study suggested that MRL-lpr/lpr mice treated with tamoxifen (TAM) had less severe proteinuria, reduced serum titre of anti-dsDNA autoantibodies and an increased survival rate. To investigate further the regulatory mechanisms of TAM on MRL-lpr/lpr female mice, a total dose of 200 microg per mice (5.5 mg/kg) was given every 2 weeks subcutaneously, while the control mice were injected with oil only. After being treated with TAM four times, the mice were killed and cellular functions were evaluated. The TAM-treated groups had smaller sized spleen and lymph nodes. Flow cytometric analysis of splenocytes had a significantly lower percentage of cell number of T cells and double negative T cells (CD4- CD8- T cells). There was no difference in cytokine production (interleukin (IL)-2, IL-4, IL-5, IL-10 and interferon-gamma (IFN-gamma)) from splenocytes stimulated with concanavalin A (Con A) or cytokines (IL-6) secreted by peritoneal exudate cells when stimulated with lipopolysaccharide (LPS). However, IL-2 from lymph node cells was significantly higher on TAM-treated mice. Finally, splenocytes or purified T cells stimulated with anti-CD3 antibody plus cross-linking immunoglobulin G (IgG) of the TAM-treated group had higher 3H-incorporation of proliferation assay compared with that of control groups. In vitro study further demonstrated that IL-2-activated proliferation of lymph node double negative (DN) T cells can be inhibited by TAM treatment in a dose-dependent manner. Our finding demonstrated that TAM may potentially influence T cells and modulate the immune function, which offers a novel approach to explore the feasibility of hormone therapy for autoimmune diseases.

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.

Th1 and Th2 T helper cell subsets affect patterns of injury and outcomes in glomerulonephritis

The recognition that human immune responses can be directed by two different subsets of T helper cells (Th1 and Th2) has been an important development in modern immunology. Immune responses polarized by either the Th1 or Th2 subset predominance result in different inflammatory effector pathways and disease outcomes. Many autoimmune diseases are associated with either Th1- or Th2- polarized immune responses. Although these different immune response patterns are relevant to glomerulonephritis (GN), little attention has been paid to the consequences of Th1 or Th2 predominance of nephritogenic immune responses for the pattern and outcome of GN. Unlike other autoimmune conditions, GN results from a variety of different immune responses and has a range of histologic features and immune effectors in glomeruli. This review assesses the data available from studies of experimental and human GN that address the Th1 or Th2 predominance of nephritogenic immune responses and their relevance to the different histopathological patterns and outcomes of GN. In particular, the evidence that Th1-predominant nephritogenic immune responses are associated with severe proliferative and crescentic GN is presented.

Exogenous dehydroepiandrosterone modified the expression of T helper-related cytokines in NZB/NZW F1 mice

The onset of lupus-like disease in NZB/NZW F1 mice was correlated with the expression of IL-10 at 4 m of age, and with a sequential enhanced expression of IFN-gamma and IL-6 between 6 to 8 m of age. The expression of IFN-gamma and IL-6 was associated with exacerbation of disease symptom, production of anti-DNA antibody, and increase in total serum IgG1. Exogenous dehydroepiandrosterone (DHEA) given in animal diet significantly prolonged survival, and delayed formation of autoantibody of NZB/NZW F1 mice as compared to mice fed on control diet. The effect of DHEA paralleled a delay in the expression of IL-10 and IL-6 and an earlier detection of IL-12 transcripts. Moreover, DHEA-fed mice had higher serum IgG2a level than control diet-fed mice. Collectively, DHEA may modify the activation of distinct subset of T helper cells in NZB/NZW F1 mice at different phases of disease progression.

IFN-γ Receptor Deletion Prevents Autoantibody Production and Glomerulonephritis in Lupus-Prone (NZB × NZW)F1 Mice

(NZB × NZW)F1 female (BW) mice spontaneously develop an autoimmune disease, characterized by the production of autoantibodies (autoAbs) and glomerulonephritis, which can be delayed by neutralizing IFN-γ Abs and accelerated by IFN-γ injections. To define the role of IFN-γ in the pathogenesis of glomerulonephritis, we established a population of BW mice deficient in IFN-γR (BWγR−/−) by repeated crossing; these mice were compared with BWγR+/+ and +/− littermates. Of the BWγR+/+ and +/− mice, 50% showed immune complex glomerulonephritis with heavy proteinuria at 8 mo of age, while only 10% of the BWγR−/− mice were affected at 14 mo. The serum concentration of anti-dsDNA and anti-histone Abs was dramatically reduced in BWγR−/− mice. The role of IFN-γ in promoting class switch to IgG2a and IgG3 could not fully account for the impaired production of anti-dsDNA in BWγR−/− animals since, IgM and IgG1 levels were also reduced. There was a high incidence of B cell lymphoma in the BWγR−/− mice, which might be related to the suppression of autoAb production. Thus, the absence of glomerulonephritis in BWγR−/− mice is likely due to a dramatic yet unexplained effect of the inactivation of IFN-γ signaling on autoAb production.

Phenotypic and functional analysis of activated B cells of autoimmune NZB x NZW F1 mice

Polyclonal B-cell activation is the central theme in the production of autoantibodies and possible activation of autoreactive T cells in both human and murine lupus. The abnormal expansion of CD5+ B cells in murine lupus has been suggested, in particular, to be one of the most characteristic findings in these mice. Activated B cells can be separated from the B cells of resting stage by the difference in cell density. The aim of this study was to investigate the characteristics of different densities of the spleen cells separated by gradient density. Furthermore, the ability of anti-DNA antibody secretion in each percoll gradient fraction of B cells was also analysed. The results showed: a higher percentage of CD5+ B cells, which corresponded to the activated B-cell population, in percoll gradient 1 and 2 fractions; that splenic B cells of NZB/W F1 mice had proliferative response to interleukin (IL)-4 or IL-5 but not to IL-10 or interferon-gamma (IFN-gamma); and that B cells isolated by percoll gradient produced anti-DNA antibody after stimulation with lipopolysaccharide (LPS) plus IL-5 and IFN-gamma, but not IL-4 and IL-10. These data suggest that B cells at different stages of activation express differential characteristics and functions.

Cytokine mRNA expression in the B/W mouse model of systemic lupus erythematosus--analyses of strain, gender, and age effects

To gain a better understanding of inherent gender-related effects on autoimmunity, cytokine genes were examined in female and male New Zealand Black X New Zealand White (B/W) mice, which are a murine model of systemic lupus erythematosus (SLE). In preliminary studies, semiquantitative reverse transcriptase-polymerase chain reaction analysis showed a trend for B/W spleen cell interferon gamma (IFN-gamma) mRNA in B/W female spleen cells to exceed that of males. This difference was obliterated following concanavalin A (Con A) stimulation. Spleen cells from B/W mice of both sexes were then examined at 6, 18, and 27 weeks of age, and results were compared with matched groups of nonautoimmune DBA/2 mice. Pooled splenocytes from all 12 groups of animals were compared simultaneously for expression of mRNA specific for IFN-gamma, interleukin 4 (IL-4) and interleukin 6 (IL-6). Strain was a potent influence on cytokine transcripts. In unstimulated splenocytes from female and male B/W mice, there was a notable trend for IFN-gamma and IL-6 mRNA expression to exceed transcripts from nonautoimmune DBA/2 mice. When comparisons were carried out by gender, a highly significant increase of IFN-gamma transcripts was apparent in B/W females compared to B/W males at the age of 27 weeks. Following Con A incubation, strain and gender differences were eliminated. IL-4 transcript expression was similar in all pools of cells, and age was not an important factor in expression of any transcript. This study represents the first examination of multiple cytokine transcripts in lymphoid cells from B/W mice. In this hormone-sensitive model of SLE, strain and gender determined in vivo expression of IFN-gamma and IL-6 mRNA.

Altered response to and production of TGF-beta by B cells from autoimmune NZB mice

New Zealand Black (NZB) mice spontaneously develop immune dysfunction manifested as autoimmune hemolytic anemia and systemic lupus erythematosus. In later life, a subset of these mice develop clonal CD5+ B cell tumors analogous to human chronic lymphocytic leukemia (CLL). NZB disease is marked by B cell hyperactivity characterized by spontaneous immunoglobulin secretion and proliferation. Elimination of autoreactive lymphocytes by apoptosis is a vital mechanism to prevent expansion of self-reactive lymphocyte population. TGF-beta appears to be an important factor in normal and abnormal immune regulation and this cytokine may play a role in the development of chronic human B cell tumors. We asked whether the response to or production of TGF-beta by NZB B cells was aberrant and could contribute to disease development. In this study, we demonstrated that the apoptotic response to TGF-beta was increased in B cells from NZB mice compared to B cells from normal BALB/c mice. The increased apoptosis was related to endogenous activation and was possibly mediated through increased expression of the TGF-beta Type II receptor. Despite functional differences between CD5-negative B cells and CD5-positive B cells, TGF-beta induced apoptosis in both populations to a similar extent. NZB B cells also secrete increased active TGF-beta compared to BALB/c B cells. We suggest that the aberrant secretion of active TGF-beta and the increased response to the apoptotic effects of TGF-beta by NZB B cells may play a role in the disease process of these mice, perhaps attempting to limit the autoimmune phenomena, but possibly also contributing to generalized immunosuppression. We also suggest that the CD5(+) tumors in the NZB mouse may not be a fully appropriate model of human CLL, since CLL B cells are abnormally resistant to the apoptotic effects of TGF-beta.