SWR X NZB)F1 Research Articles

Preclinical stage abundance and nuclear antigen reactivity of faecal Immunoglobulin A vary among males and females of lupus-prone mouse models.

Systemic lupus erythematosus (SLE) is characterized by the production of pathogenic autoantibodies with nuclear antigen (nAg) specificity. Using (SWRxNZB)F1 (SNF1) mice, we showed higher levels of Immunoglobulin A (IgA) production in the intestine and the nAg reactivity of faecal IgA under lupus susceptibility. Here, we determined whether the faecal IgA abundance and nAg reactivity are higher in, different among, various lupus-prone preclinical models (MRL/lpr, NZBxNZW-F1, SNF1, NZM2410 and NZM2328). We also determined whether the faecal IgA nAg reactivity at preseropositive ages correlates with the eventual serum autoantibody levels in males and females of these mouse models. We show that age-dependent increase in the abundance and nAg reactivity of faecal IgA can vary among different lupus-prone mouse models. Importantly, faecal IgA in these mice show significant levels of nAg reactivity, starting as early as at juvenile age. Furthermore, the pre-seropositive stage nAg reactivity of faecal IgA in most lupus-prone strains correlates well with that of eventual, seropositive stage systemic autoantibody levels. Gender differences in serum autoantibody levels were preceded by similar differences in the faecal IgA abundance and nAg reactivity. These observations suggest that faecal IgA features, nAg reactivity particularly, could serve as a biomarker for early prediction of the eventual systemic autoimmunity in lupus-prone subjects.

Abundance and nuclear antigen reactivity of intestinal and fecal Immunoglobulin A in lupus-prone mice at younger ages correlate with the onset of eventual systemic autoimmunity

Our recent studies, using (SWRxNZB)F1 (SNF1) mice, showed a potential contribution of the gut microbiota and pro-inflammatory immune responses of the gut mucosa to systemic autoimmunity in lupus. Here, using this mouse model, we determined the abundance and the nAg reactivity of IgA antibody produced in the intestine under lupus susceptibility. Intestinal lymphoid tissues from SNF1 mice, females particularly, showed significantly higher frequencies of nAg (dsDNA and nucleohistone) reactive IgA producing B cells compared to B6 females. Most importantly, younger age fecal IgA -abundance and -nAg reactivity of lupus-prone mice showed a positive correlation with eventual systemic autoimmunity and proteinuria onset. Depletion of gut microbiota in SNF1 mice resulted in the diminished production of IgA in the intestine and the nAg reactivity of these antibodies. Overall, these observations show that fecal IgA features, nuclear antigen reactivity particularly, at preclinical stages/in at-risk subjects could be predictive of autoimmune progression.

Gut microbiota differently contributes to intestinal immune phenotype and systemic autoimmune progression in female and male lupus-prone mice

The risk of developing systemic lupus erythematosus (SLE) is about 9 times higher in women as compared to men. Our recent report, which used (SWRxNZB) F1 (SNF1) mouse model of spontaneous lupus, showed a potential link between immune response initiated in the gut mucosa at juvenile age (sex hormone independent) and SLE susceptibility. Here, using this mouse model, we show that gut microbiota contributes differently to pro-inflammatory immune response in the intestine and autoimmune progression in lupus-prone males and females. We found that gut microbiota composition in male and female littermates are significantly different only at adult ages. However, depletion of gut microbes causes suppression of autoimmune progression only in females. In agreement, microbiota depletion suppressed the pro-inflammatory cytokine response of gut mucosa in juvenile and adult females. Nevertheless, microbiota from females and males showed, upon cross-transfer, contrasting abilities to modulate disease progression. Furthermore, orchidectomy (castration) not only caused changes in the composition of gut microbiota, but also a modest acceleration of autoimmune progression. Overall, our work shows that microbiota-dependent pro-inflammatory immune response in the gut mucosa of females initiated at juvenile ages and androgen-dependent protection of males contribute to gender differences in the intestinal immune phenotype and systemic autoimmune progression.

Pristane-Accelerated Autoimmune Disease in (SWR X NZB) F1 Mice Leads to Prominent Tubulointerstitial Inflammation and Human Lupus Nephritis-Like Fibrosis.

Mouse models lupus nephritis (LN) have provided important insights into disease pathogenesis, although none have been able to recapitulate all features of the human disease. Using comprehensive longitudinal analyses, we characterized a novel accelerated mouse model of lupus using pristane treatment in SNF1 (SWR X NZB F1) lupus prone mice (pristane-SNF1 mice). Pristane treatment in SNF1 mice accelerated the onset and progression of proteinuria, autoantibody production, immune complex deposition and development of renal lesions. At week 14, the pristane-SNF1 model recapitulated kidney disease parameters and molecular signatures seen in spontaneous disease in 36 week-old SNF1 mice and in a traditional IFNα-accelerated NZB X NZW F1 (BWF1) model. Blood transcriptome analysis revealed interferon, plasma cell, neutrophil, T-cell and protein synthesis signatures in the pristane-SNF1 model, all known to be present in the human disease. The pristane-SNF1 model appears to be particularly useful for preclinical research, robustly exhibiting many characteristics reminiscent of human disease. These include i) a stronger upregulation of the cytosolic nucleic acid sensing pathway, which is thought to be key component of the pathogenesis of the human disease, and ii) more prominent kidney interstitial inflammation and fibrosis, which have been both associated with poor prognosis in human LN. To our knowledge, this is the only accelerated model of LN that exhibits a robust tubulointerstitial inflammatory and fibrosis response. Taken together our data show that the pristane-SNF1 model is a novel accelerated model of LN with key features similar to human disease.

Differential effect of neonatal thymectomy on systemic and organ-specific autoimmune disease.

Thymectomy on day 3 after birth (d3tx) depletes CD4+CD25+ regulatory T cells leading to multiple independent organ-specific autoimmune diseases. However, systemic autoimmune disease such as systemic lupus erythematosus has not been reported in d3tx mice. Herein, we investigate the effect of d3tx on spontaneous autoantibody response and immune complex glomerulonephritis (GN) in the lupus-prone (SWR x NZB)F1 (SNF1) mice. The d3tx SNF1 mice developed accelerated antibody responses to double-stranded DNA and DNA-histone complexes, and an increased frequency of activated CD4+ T cells. Unexpectedly, the renal histopathology and mortality from GN were significantly ameliorated in d3tx SNF1 mice, which concomitantly exhibited a Th2-biased antibody response. By 16 weeks, the d3tx mice had higher levels of total and autoantigen-specific IgG1, and at 12 months, the autoantigen-specific IgG2a was significantly below that of the sham thymectomized mice. These differences corresponded with reduction in total and autoantigen-specific IgG2a in the renal eluates of the d3tx mice. In addition, while all the mice had immune complex deposition in the mesangium and peripheral capillary loops of the glomeruli, IgG2a and C3 deposits restricted to the mesangial regions alone were more frequent in d3tx mice. D3tx SNF1 mice, protected from lupus-like GN, developed organ-specific autoimmune responses and diseases including prostatitis, orchitis and oophoritis, and antibodies to prostate, cardiac and skeletal muscle antigens. Therefore, d3tx paradoxically protects SNF1 mice from genetically prone lupus-like GN, yet promotes de novo organ-specific autoimmunity.

Junctional region sequences of T-cell receptor beta-chain genes expressed by pathogenic anti-DNA autoantibody-inducing helper T cells from lupus mice: possible selection by cationic autoantigens.

We rescued from the spleens of 10 (SWR x NZB)F1 (SNF1) mice with lupus nephritis the T cells that were activated in vivo and cloned 268 T-cell lines and hybridomas. Only 12% of these T-cell clones had the functional ability to preferentially augment the production of pathogenic anti-DNA autoantibodies. Among these, 16 helper T-cell (Th-cell) clones that were mostly CD4+ and had the strongest autoantibody-inducing ability were analyzed for T-cell receptor (TCR) beta-chain gene usage. Seven of the 16 Th-cell clones expressed beta-chain variable region (V beta) V beta 8 (8.2 or 8.3) genes and three expressed V beta 4, whereas two clones each used a V beta 1 or V beta 2 or V beta 14 gene, suggesting some restriction in TCR gene usage. Although heterogeneous, the V-D-J junctional region sequences of TCR beta-chain genes used by these Th-cell clones invariably encoded one or more negatively charged residues (aspartic or glutamic acid) that had been generated in most cases by unspecified nucleotide (N) additions. Representative pathogenic autoantibody-inducing Th-cell clones could rapidly induce the development of lupus nephritis when injected into young prenephritic SNF1 mice. The pathogenic autoantibody-inducing Th cells expressing the anionic residues in their TCR beta-chain junctions (complementarity-determining region CDR3) were probably selected by some cationic autoantigenic peptide presented by the anti-DNA B cells they preferentially helped. These results offer a clue regarding the nature of the primary autoantigen that may drive the pathogenic autoimmune response in lupus.

T cell receptor Vβ genes expressed by IgG anti‐DNA autoantibody‐inducing T cells in lupus nephritis: Forbidden receptors and double‐negative T cells

In the (SWR x NZB)F1 (SNF1) model of lupus nephritis, pathogenic variety of IgG anti-DNA autoantibodies are induced by certain T helper (Th) cells that are either CD4+ or CD4-CD8- (double negative; DN) in phenotype. From the spleens of eight SNF1 mice with lupus nephritis, 149 T cell lines were derived and out of these only 25 lines (approximately 17%) were capable of augmenting the production of pathogenic anti-DNA autoantibodies. Herein, we analyzed the T cell receptor (TcR) V beta genes used by 16 such pathogenic autoantibody-inducing Th cell lines. Twelve of the Th lines were CD4+ and among these five lines expressed V beta 8 (8.2 or 8.3). The V beta 8 gene family is contributed by the NZB parent to the SNF1 mice, since it is absent in the SWR parental strain. Three other CD4+ Th lines expressed V beta 4, another was V beta 2+ and one line with poor autoantibody-inducing capability expressed V beta 1. Four autoantibody-inducing Th lines from the SNF1 mice had a DN phenotype and these lines were also autoreactive, proliferating in response to syngeneic spleen cells. Among these DN Th lines, two expressed V beta 6 and one expressed V beta 8.1 TcR. Both of these are forbidden TcR directed against Mls-1a (Mlsa) autoantigens expressed by the SNF1 mice and such autoreactive T cells should have been deleted during thymic ontogeny. Thus, the DN Th cells of non-lpr SNF1 mice are different from the DN cells or MRL-lpr which lack helper activity and do not express forbidden TcR. The spleens of 6 out of 19 nephritic SNF1 animals tested also showed an expansion of forbidden autoreactive TcR+ cells that were mainly DN. Two of these animals expressed high levels of V beta 6 (anti-Mlsa) and V beta 11 (anti-I-E) TcR+ cells, three others had high levels of V beta 11+ cells alone and one animal had an expanded population of V beta 17a+ (anti-I-E) cells. The I-E-reactive TcR again should have been eliminated in the SNF1 thymus, since they express I-E molecules contributed by the NZB parent. The SWR parents of SNF1, are I-E-; moreover, they lack the V beta 11 gene but they express V beta 17a in peripheral T cells. Whereas the NZB parents are I-E+, they lack a functional V beta 17a gene and they delete mature V beta 11+ T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

V region sequences of an idiotypically connected family of pathogenic anti-DNA autoantibodies.

The H and L chain V region sequences of nine anti-DNA mAb that are representative of a pathogenic population of autoantibodies produced by the nephritis prone (SWR x NZB)F1 (SNF1) mice, were determined. These nine anti-DNA autoantibodies were idiotypically connected members of a cross-reactive Id family called the Id564 cluster. Moreover, these autoantibodies were all cationic in charge, IgG2b in isotype, and their H chain C regions had the normal SWR parent's allotype. Although derived from two different SNF1 animals, these pathogenic autoantibodies possessed highly homologous Leader-VH sequences that could account for their idiotypic cross-reactivity. Furthermore, the VH region sequences of these anti-DNA antibodies contained numerous basic residues that could impart their cationic charge. The Leader-VH sequences of these autoantibodies were also highly homologous to that of an anti-NP antibody-related germ-line gene of C57BL/6 mice, called VH-23. Among these nine pathogenic autoantibodies, three sets of clonally related anti-DNA antibodies could be identified. Thus the Id564 cluster of cationic anti-DNA autoantibodies of SNF1 mice are encoded by highly related VH genes, and this idiotypically connected population of pathogenic autoantibodies are selected to undergo an oligoclonal expansion in the lupus-prone SNF1 mice.