Glomerular Immune Complex Research Articles

Role of T cell mediated inflammation in lupus-like glomerulonephritis (GN) (93.40)

Abstract Renal involvement in lupus is characterized by glomerular immune complexes, acute proliferative GN and progressive renal failure. To investigate the pathogenic role of T cells in renal lupus, an antigen-specific model of GN was established. A novel, anti-α8 integrin immunoliposomal delivery system (α8ILs) was designed for targeted delivery to the renal glomerulus. Ovalbumin loaded α8ILs (ova-α8ILs) were injected i.v. into C57BL/6 mice leading to a rapid delivery of ova in the glomerular mesangium. Injection of ova-α8ILs followed by ova-reactive transgenic OT2 cells activated in vitro, resulted in GN. On day 7 after injection, the renal cortex showed T cell, macrophage and dendritic cell infiltration. To mimic lupus GN, mice were injected with ova-α8ILs and mouse anti-ova serum forming glomerular immune complexes. This was followed by injection of naïve CSFE labeled OT2 cells. Two days after cell transfer, mice with glomerular immune complexes showed dividing OT2 cells preferentially in renal lymph nodes compared to mice given ova-α8ILs alone. Recently, macrophage infiltration into the renal interstitium has been identified as the harbinger of renal failure. Our data suggest that glomerular antigen-specific T cell infiltration may be sufficient for recruitment of macrophages into the renal cortex and the onset of progressive renal inflammation. In addition, glomerular immune complexes lead to a rapid, local activation of glomerular antigen reactive T cells.

From mother to child--transplacental effect of AT1R-AAin preeclampsia

Preeclampsia is a common hypertensive disorder of pregnancy and a leading cause of maternal and foetal morbidity and mortality worldwide. Preeclampsia requires the presence of the placenta and generally dramatically resolves after placental delivery. The abnormal placentation with failure of trophoblast remodelling of uterine spiral arterioles represents a point where current theories on mechanisms responsible for the condition converge [1]. Various pathways have been proposed to contribute to placental disease. Two major recent concepts, namely, autoimmunity and anti-angiogenesis, have helped us gain new insights into this ‘disease of theories’. Possible mediators leading to impaired angiogenesis in the placenta were recently reviewed [2]. The autoimmunity notion received support with the discovery of autoantibodies directed against the angiotensin (Ang) II Type 1 receptor (AT1R-AA) in the serum of preeclamptic women [3]. AT1R-AA activate the AT1R and induce a cascade of events in various cell types, similar to the actions of Ang II [4]. Increased oxidative stress, increased production of soluble fms-like tyrosine kinase (sFlt-1) in the placenta and initiation of pro-inflammatory and pro-coagulation responses all appear to be key mechanisms resulting from AT1R-AA actions [5]. AT1R-AA were also found in a rodent model for preeclampsia. In that model, the dams of female rats transgenic for the human angiotensinogen gene crossed with male rats transgenic for the human renin gene developed severe (telemetrymeasured) hypertension and albuminuria in the latter half of pregnancy, accompanied by glomerular endotheliosis [6]. Thus, many features of the preeclampsia-related maternal syndrome including hypertension, proteinuria and generalized endothelial dysfunction were attributed to circulating AT1R-AA. Preeclamptic AT1R-AA are IgG3 subclass immunoglobulins that target the structures contained in the second extracellular loop of AT1R and induce agonistic responses similar to Ang II despite a different binding site from the natural ligand [3]. Their actions can be neutralized with the corresponding seven-amino-acid peptide sequence or pharmacologic blockade of the AT1R. Recent studies on the pathogenesis of preeclampsia focused mainly on the features of the maternal syndrome, as preeclampsia can lead to serious maternal and foetal complications. Agonistic antibody-mediated AT1R stimulation has been demonstrated in severe vascular renal allograft rejection and the passive transfer of human IgG containing AT1R-AA induced vascular lesions similar to the human disease. Furthermore, AT1R-AA led to increased blood pressure in otherwise non-rejecting and normotensive transplanted animals [7]. Investigators from the University of Texas in Houston pursued a similar strategy of passive human IgG transfer. They recently showed that AT1R-AA recovered from the circulation of women with preeclampsia induced preeclampsia-like generalized endothelial dysfunction in pregnant mice. Short duration (5 days) of the passive transfer induced an increase in tail-cuff blood pressure measurements. Links to impaired placental angiogenesis was demonstrated with an increase in sFlt concentrations in the serum of these pregnant mice [8]. sFlt is a shorter splice variant of the functional receptor that lacks the transmembrane domain. The shortened version interferes with angiogenesis and thereby placental development. Together with previous f indings implicating overproduction of plasminogen activator inhibitor-1 and tissue factor in human trophoblast cells, their findings provided further evidence that AT1R-AA may have a causative role in abnormal placentation. Some prototypic features of maternal syndrome in terms of swelling of the endothelial cells (glomerular endotheliosis) were found in the antibody-transferred pregnant mice. However, the mouse model differed from the human disease. For instance, electron microscopic analysis revealed subendothelial deposits of immune complexes. Glomerular immune complex deposition is not common in human preeclampsia [9] and it remains to be determined whether or not the mice developed antibodies against human AT1R-AA IgG used in the transfer experiments. The team from Houston now focused on foetal complications. Intrauterine growth restriction (IUGR) can be

A New Model of Induced Experimental Systemic Lupus Erythematosus (SLE) in Pigs and Its Amelioration by Treatment with a Tolerogenic Peptide

Systemic lupus erythematosus (SLE) is characterized by a variety of autoantibodies and systemic clinical manifestations. A tolerogenic peptide, hCDR1, ameliorated lupus manifestations in mice models. The objectives of this study were to induce experimental SLE in pigs and to determine the ability of hCDR1 to immunomodulate the disease manifestations. We report here the successful induction, by a monoclonal anti-DNA antibody, of an SLE-like disease in pigs, manifested by autoantibody production and glomerular immune complex deposits. Treatment of pigs with hCDR1 ameliorated the lupus-related manifestations. Furthermore, the treatment downregulated the gene expression of the pathogenic cytokines, interleukin (IL)-1beta, tumor necrosis factor alpha, interferon gamma, and IL-10, and upregulated the expression of the immunosuppressive cytokine transforming growth factor beta, the antiapoptotic molecule Bcl-xL, and the suppressive master gene, Foxp3, hence restoring the expression of the latter to normal levels. Thus, hCDR1 is capable of ameliorating lupus in large animals and is a potential candidate for the treatment of SLE patients.

Pathogenesis of kidney disease in systemic lupus erythematosus

A combination of systemic autoimmunity and tissue response to immune injury underlie renal involvement in lupus erythematosus. In this review, we discuss recent literature investigating pathogenetic mechanisms of lupus glomerulonephritis. In lupus glomerulonephritis, glomerular immune complexes were believed to be the primary mediators of renal disease. Recent studies make it apparent that autoantibodies of multiple specificities participate in the formation of immune complexes, deposited in the kidneys. Renal infiltration by T cells, macrophages, and dendritic cells have a dominant role in the progression of lupus glomerulonephritis leading to renal failure. Activation of Toll-like receptors modulates autoantibody production and systemic interferon responses. However, glomerular cell responses to immune injury influence disease outcome. In addition, new insights on the genetics of susceptibility to end-organ damage in lupus glomerulonephritis have been discovered. Differential glomerular responses reflected in gene expression profiles during disease progression provide potential markers for diagnosis of lupus glomerulonephritis progression and flares. In addition, studies of end-organ responses provide new targets for therapeutic interventions. Lupus glomerulonephritis is a prototype of immune complex disease mediated by autoantibodies of multiple specificities, one of which is anti-DNA. Murine models of spontaneous systemic lupus erythematosus have been critical for understanding the underlying disease. Recent studies demonstrate that in addition to systemic autoimmunity, end-organ responses, and end-organ resistance to damage are also critical in determining disease outcome. This understanding should influence design of novel therapeutic approaches in systemic lupus erythematosus.

Deletion of Activating Fcγ Receptors Does Not Confer Protection in Murine Cryoglobulinemia-Associated Membranoproliferative Glomerulonephritis

Many types of glomerulonephritis are initiated by the deposition of immune complexes, which induce tissue injury via either engagement of Fc receptors on effector cells or via complement activation. Four murine Fcgamma receptors (FcgammaRs) have been identified at present. Ligand binding to FcgammaRI, III, and IV induces cell activation via the immunoreceptor tyrosine-based activation motif on the common gamma chain (FcRgamma). In this study, FcRgamma chain knockout (FcRgamma(-/-)) mice were crossed with thymic stromal lymphopoietin transgenic (TSLPtg) mice, which develop cryoglobulinemic membranoproliferative glomerulonephritis (MPGN). Female mice were studied at 30 and 50 days of age, when MPGN is in early and fully developed stages, respectively. Both TSLPtg and TSLPtg/FcRgamma(-/-) mice developed MPGN with massive glomerular immune deposits, mesangial cell proliferation, extensive mesangial matrix accumulation, and macrophage influx. TSLPtg/FcRgamma(-/-) mice had more glomerular immune complex deposits and higher levels of circulating cryoglobulins, IgG2a, IgG2b, and IgM, compared with TSLPtg mice. TSLPtg and TSLPtg/FcRgamma(-/-) mice developed similar levels of proteinuria. These results demonstrated that deletion of activating FcgammaRs does not confer protection in this model of immune complex-mediated MPGN. The findings contradict accepted paradigms on the role of activating FcgammaRs in promoting features of glomerulonephritis as seen in other model systems. We speculate engagement of FcgammaRs on cells such as monocytes/macrophages may be important for the clearance of deposited immune complexes and extracellular matrix proteins.

Circulating chromatin–anti-chromatin antibody complexes bind with high affinity to dermo-epidermal structures in murine and human lupus nephritis

Murine and human lupus nephritis are characterized by glomerular deposits of electron-dense structures (EDS). Dominant components of EDS are chromatin fragments and IgG antibodies. Whether glomerular EDS predispose for similar deposits in skin is unknown. We analysed (i) whether dermo-epidermal immune complex deposits have similar molecular composition as glomerular deposits, (ii) whether chromatin fragments bind dermo-epidermal structures, and (iii) whether deposits in nephritic glomeruli predispose for accumulation of similar deposits in skin. Paired skin and kidney biopsies from nephritic (NZBxNZW)F1 and MRL-lpr/lpr mice and from five patients with lupus nephritis were analysed by immunofluorescence, immune electron microscopy (IEM) and co-localization TUNEL IEM. Affinity of chromatin fragments for membrane structures was determined by surface plasmon resonance. Results demonstrated (i) presence of EDS containing chromatin fragments and IgG in both organs in nephritic patients, (ii) chromatin fragments possessed high affinity for dermo-epidermal laminins and collagens, (iii) glomerular immune complex deposits did not predict similar interstitial deposits in skin, although such complexes were present in capillary lumina in glomeruli and skin of all nephritic individuals. Thus, chromatin-IgG complexes accounting for lupus nephritis seem to reach skin through circulation, but other undetermined factors are required for these complexes to deposit within skin membranes.

Blockade of the CD30/CD30L pathway inhibits renal disease in young, SLE-prone NZB/W F1 mice (50.41)

Abstract CD30 and CD30L are interacting members of the TNFR and TNF family, respectively. CD30 is expressed by subsets of activated T and B cells, whereas CD30L is expressed by subsets of activated T cells, macrophages and dendritic cells. The CD30 / CD30L interaction modulates T cell activation, germinal center formation and antibody isotype class switching. Given the importance of this pathway to B cell function, we tested the hypothesis that blockade of the CD30 / CD30L pathway would decrease or abrogate autoantibody formation and renal disease in the NZB/W F1 murine model of systemic lupus erythematosis (SLE). Young (5 mo) NZB/W F1 mice were treated with 300 μg CD30L blocking (M15-N297A) or blocking / depleting (M15-IgG2a) antibody weekly for 3 months during the onset of autoimmunity. Both treatments a) reduced the onset and severity of proteinuria, b) significantly decreased the severity of renal histologic scores, c) decreased glomerular immune complex and complement deposition and d) these effects were associated with reduced production of anti-DNA antibodies of the IgG, but not IgM isotype. CD30 / CD30L blockade may be a viable approach for the treatment of SLE.

Focal Glomerular Immune Complex Deposition: Possible Role of Periglomerular Fibrosis/Atubular Glomeruli

Consensus exists among renal pathologists that, in biopsies with immune complex glomerulonephritis, even a single glomerulus with open capillary loops may be sufficient for immunofluorescence and/or electron microscopy evaluation because immune complex deposition is a diffuse phenomenon. However, we have encountered renal biopsies with focal absence of immune complexes in glomeruli on either immunofluorescence or electron microscopy examination despite presence of open glomerular capillary loops. To evaluate renal biopsies with focal immune complex deposition and look for any subtle or unusual morphologic changes in the glomeruli (and in the biopsy in general). Native and transplant renal biopsies were reviewed. All biopsies had been triaged and processed according to our routine protocol for light microscopy, immunofluorescence, and electron microscopy examination. Of 2018 renal biopsies from December 2005 to December 2007, we found 10 such biopsies; 5 native and 5 transplant kidney biopsies. We found that the glomeruli with absent immune complex deposits had periglomerular fibrosis with open, albeit, wrinkled appearing capillary loops but no glomerular sclerosis. We hypothesize that these histologic features are indicative of nonfunctional glomeruli and may be associated with disconnection between the Bowman capsule and proximal tubule (atubular glomeruli). These glomeruli may not have effective filtration, despite some degree of circulation through the open capillary loops, and therefore are unable to accumulate immune complex deposits. If biopsies are small and only such glomeruli are available for immunofluorescence or electron microscopy examination, the absence of immune complex deposition in them should be evaluated carefully.

Focal glomerular immune complex deposition: possible role of periglomerular fibrosis/atubular glomeruli.

Abstract Context.—Consensus exists among renal pathologists that, in biopsies with immune complex glomerulonephritis, even a single glomerulus with open capillary loops may be sufficient for immunofluorescence and/or electron microscopy evaluation because immune complex deposition is a diffuse phenomenon. However, we have encountered renal biopsies with focal absence of immune complexes in glomeruli on either immunofluorescence or electron microscopy examination despite presence of open glomerular capillary loops. Objective.—To evaluate renal biopsies with focal immune complex deposition and look for any subtle or unusual morphologic changes in the glomeruli (and in the biopsy in general). Design.—Native and transplant renal biopsies were reviewed. All biopsies had been triaged and processed according to our routine protocol for light microscopy, immunofluorescence, and electron microscopy examination. Results.—Of 2018 renal biopsies from December 2005 to December 2007, we found 10 such biopsies; 5 native...

The immature B‐cell subpopulation with low RAG1 expression is increased in the autoimmune New Zealand Black mouse

Receptor editing is believed to play a critical role in immunological tolerance by altering the specificity of autoreactive B cells that emerge in the bone marrow. To study whether receptor editing is altered in autoimmune disease, recombination activation gene 1 (rag1) transcription in B cells from New Zealand Black (NZB) mice was examined by introducing a GFP gene at the rag1 locus. Female NZB(RAG1-GFP) mice generated autoantibodies and glomerular immune complexes. NZB(RAG1-GFP) mice did not display increased RAG1-GFP signal in B-1 and B-2 cells from the spleen and peritoneal cavity even following in vitro stimulation compared with C57BL/6(RAG1-GFP) control mice. The early B cells in the bone marrow were classified into RAG1-GFP(-) and RAG1-GFP(+) subpopulations. The RAG1-GFP(-) immature B-cell population was in the minority in C57BL/6(RAG1-GFP) mice but was markedly increased in NZB(RAG1-GFP) mice. RAG1-GFP(-) immature B cells from NZB(RAG1-GFP) mice differentiated into anti-dsDNA Ab-producing cells after stimulation by LPS in vitro. RAG1-GFP(-) immature B cells from NZB(RAG1-GFP) mice displayed a different expression profile of transcription factors required for receptor editing, including pax5 and irf4, in comparison with the RAG1-GFP(+) immature B-cell population. In conclusion, the early B-cell subpopulation, which exhibits low RAG1 expression and presumably concomitantly low receptor editing, was found to be increased in NZB mice.

B cell antigen receptor signal strength and peripheral B cell development are regulated by a 9-O-acetyl sialic acid esterase

We show that the enzymatic acetylation and deacetylation of a cell surface carbohydrate controls B cell development, signaling, and immunological tolerance. Mice with a mutation in sialate:O-acetyl esterase, an enzyme that specifically removes acetyl moieties from the 9-OH position of α2–6-linked sialic acid, exhibit enhanced B cell receptor (BCR) activation, defects in peripheral B cell development, and spontaneously develop antichromatin autoantibodies and glomerular immune complex deposits. The 9-O-acetylation state of sialic acid regulates the function of CD22, a Siglec that functions in vivo as an inhibitor of BCR signaling. These results describe a novel catalytic regulator of B cell signaling and underscore the crucial role of inhibitory signaling in the maintenance of immunological tolerance in the B lineage.

Attenuation of immune complex nephritis in NZB/WF1 mice by a prostacyclin analogue.

Although prostaglandins have been shown to inhibit the evolution of the nephritis in NZB/W mice, the mechanisms of this effect are unknown. To characterize such inhibition, we injected the prostacyclin (PGI2) analogue, beraprost, into NZB/W mice, using 0.5 mg, 1.0 mg or 5.0 mg beraprost/kg body weight of test animals three times in 1 week when the mice were 2 months old. Evaluation included measurement of urine albumin excretion, serological parameters and splenic T cell subset, as well as examination of renal histology by light and fluorescence microscopy. Mice given beraprost showed a marked decrease in urine albumin excretion and in glomerular hypercellularity compared with untreated controls. Maximal beneficial effects occurred when the dose was 5.0 mg/kg of beraprost. These effects correlated with a reduction of immune complex deposition in glomeruli. In addition, beraprost reduced serum levels of immunoglobulins and anti-double-stranded DNA antibodies, and decreased the number of helper (L3T4+) T cells in splenocytes. These results indicate that beraprost attenuates the nephritis of NZB/W mice, and that the source of this effect is the reduced production of autoantibodies and deposition of immune complexes in glomeruli.

Glomerular subendothelial and subepithelial immune complexes, containing the same antigen, are removed at different rates

To examine the persistence of immune deposits in the subendothelial and subepithelial areas of the glomerular basement membrane in rats, immune deposits were formed by injection of radiolabelled, cationized human serum albumin (HSA) as antigen, followed by rabbit antibodies to HSA. The disappearance of the radiolabelled antigen from immune deposits in glomeruli was described by a curve consisting of two exponential components. By electron microscopy, subendothelial and subepithelial immune deposits were initially present in glomeruli. At later time-points, only subepithelial immune deposits were present. The fast component of disappearance, attributed to subendothelial deposits, had a half-life of 3.89 +/- 0.32 h. The slow component of disappearance from glomeruli, attributed to subepithelial deposits, had a half-life of 85.5 +/- 3.1 h. Since some of the injected, radiolabelled antigen was sequestered in other compartments of the body, the possibility was raised that antigen from these sites might be released and contribute to the persistence of deposits in glomeruli. This possibility, however, was excluded when transplantation of kidneys with immune deposits to untreated recipients revealed no difference in the amount of antigen persisting in nontransplanted and transplanted kidneys.

Induction of experimental systemic lupus erythematosus (SLE) in mice with severe combined immunodeficiency (SCID).

A model in which experimental SLE is induced in normal mice by the injection of a human anti-DNA MoAb expressing a common idiotype 16/6 Id has been established in our laboratory. In the present study we have attempted the induction of experimental SLE in mice with SCID by the transfer of lymphocytes obtained from mice with experimental SLE. Disease could not be induced by direct immunization of SCID mice with the 16/6 Id nor by transfusion of normal splenocytes and immunization with the 16/6 Id thereafter. In contrast, disease was induced in SCID mice which were transplanted with splenic lymphocytes obtained from SLE afflicted BALB/c mice. The disease was expressed by the presence of high titres of antibodies and glomerular immune complex deposits were present in the kidney sections of these mice. Mice that received spleen cells from donors with experimental SLE together with the 16/6 Id developed higher titres of autoantibodies and had, in addition to the immune complex deposits, glomerular histological pathology. The model of experimental SLE induction in SCID mice should help in the elucidation of the role of different cell types in the pathogenesis of SLE.

Constitutive Production of NF-κB2 p52 Is Not Tumorigenic but Predisposes Mice to Inflammatory Autoimmune Disease by Repressing Bim Expression

Normal development of the immune system requires regulated processing of NF-kappaB2 p100 to p52, which activates NF-kappaB2 signaling. Constitutive production of p52 has been suggested as a major mechanism underlying lymphomagenesis induced by NF-kappaB2 mutations, which occur recurrently in a variety of human lymphoid malignancies. To test the hypothesis, we generated transgenic mice with targeted expression of p52 in lymphocytes. In contrast to their counterparts expressing the tumor-derived NF-kappaB2 mutant p80HT, which develop predominantly B cell tumors, p52 transgenic mice are not prone to lymphomagenesis. However, they are predisposed to inflammatory autoimmune disease characterized by multiorgan infiltration of activated lymphocytes, high levels of autoantibodies in the serum, and immune complex glomerulonephritis. p52, but not p80HT, represses Bim expression, leading to defects in apoptotic processes critical for elimination of autoreactive lymphocytes and control of immune response. These findings reveal distinct signaling pathways for actions of NF-kappaB2 mutants and p52 and suggest a causal role for sustained NF-kappaB2 activation in the pathogenesis of autoimmunity.

Activated Renal Macrophages Are Markers of Disease Onset and Disease Remission in Lupus Nephritis

Costimulatory blockade with CTLA4Ig and anti-CD40L along with a single dose of cyclophosphamide induces remission of systemic lupus erythematosus nephritis in NZB/W F(1) mice. To understand the mechanisms for remission and for impending relapse, we examined the expression profiles of 61 inflammatory molecules in the perfused kidneys of treated mice and untreated mice at different stages of disease. Further studies using flow cytometry and immunohistochemistry allowed us to determine the cellular origins of several key markers. We show that only a limited set of inflammatory mediators is expressed in the kidney following glomerular immune complex deposition but before the onset of proteinuria. Formation of a lymphoid aggregate in the renal pelvis precedes the invasion of the kidney by inflammatory cells. Regulatory molecules are expressed early in the disease process and during remission but do not prevent the inevitable progression of active inflammation. Onset of proliferative glomerulonephritis and proteinuria is associated with activation of the renal endothelium, expression of chemokines that mediate glomerular cell infiltration, and infiltration by activated dendritic cells and macrophages that migrate to different topographical areas of the kidney but express a similar profile of inflammatory cytokines. Increasing interstitial infiltration by macrophages and progressive tubular damage, manifested by production of lipocalin-2, occur later in the disease process. Studies of treated mice identify a type II (M2b)-activated macrophage as a marker of remission induction and impending relapse and suggest that therapy for systemic lupus erythematosus nephritis should include strategies that prevent both activation of monocytes and their migration to the kidney.

Microbial IgA Protease Removes IgA Immune Complexes from Mouse Glomeruli In Vivo: Potential Therapy for IgA Nephropathy

The hallmark of IgA nephropathy (IgAN), the most common form of glomerulonephritis, is the presence of mesangial deposits containing IgA, specifically the IgA1 subclass, as the most prominent component. The deposited IgA is considered to be part of an immune complex. The family of enzymes known as bacterial IgA proteases exhibits substrate specificity that is essentially limited to the hinge region of IgA1. Here we demonstrate the ability of systemically administered IgA protease to remove glomerular IgA immune complexes, both the antigen and antibody components, in a passive mouse model of IgAN. Thus, IgA protease may have potential as a therapeutic agent for human IgAN.

Sémiologie musculaire

Nephrotic syndrome is in adult patients mainly due to membranous nephropathy (MN) characterized by thickening of the glomerular basement membrane (GBM) and immune complex formation between podocytes and the GBM. Autoantibodies directed against the M-type phospholipase A2 receptor (PLA2R) and thrombospondin 1 domain-containing 7 A (THSD7A) can be used as diagnostic biomarkers. THSD7A seems to be of direct pathogenic significance as is suggested by experimental models and plasmapheresis in humans. Recently, further antigens like NELL-1 (neural tissue encoding protein with EGF-like repeats-1), exostosin 1 and 2 have been discovered. Thus, MN should be classified into antibody positive and antibody negative MN. More specific immunosuppressive treatments directed against B-cells and antibody production like rituximab have been introduced in addition to already existing immunosuppressive protocols including steroids, chlorambucil, cyclophosphamide, and calcineurin inhibitors. Antibody removal using immunoadsorption or plasmapheresis leads to short-term reduction in proteinuria and might be indicated only in patients with very severe proteinuria and complications. Studies are needed to identify a more specific immunosuppression directed against the production and effects of autoantibodies in order to protect the kidneys from autoimmune mediated tissue damage and to identify patients who require an immunosuppressive treatment, as the remission rate is high in patients with MN.

Deficiency of the type I interferon receptor protects mice from experimental lupus

Systemic lupus erythematosus (SLE) is diagnosed according to a spectrum of clinical manifestations and autoantibodies associated with abnormal expression of type I interferon (IFN-I)-stimulated genes (ISGs). The role of IFN-I in the pathogenesis of SLE remains uncertain, partly due to the lack of suitable animal models. The objective of this study was to examine the role of IFN-I signaling in the pathogenesis of murine lupus induced by 2,6,10,14-tetramethylpentadecane (TMPD). IFN-I receptor-deficient (IFNAR(-/-)) 129Sv mice and wild-type (WT) 129Sv control mice were treated intraperitoneally with TMPD. The expression of ISGs was measured by real-time polymerase chain reaction. Autoantibody production was evaluated by immunofluorescence and enzyme-linked immunosorbent assay. Proteinuria and renal glomerular cellularity were measured and renal immune complexes were examined by immunofluorescence. Increased ISG expression was observed in the peripheral blood of TMPD-treated WT mice, but not in the peripheral blood of TMPD-treated IFNAR(-/-) mice. TMPD did not induce lupus-specific autoantibodies (anti-RNP, anti-Sm, anti-double-stranded DNA) in IFNAR(-/-) mice, whereas 129Sv controls developed these specificities. Although glomerular immune complexes were present in IFNAR(-/-) mice, proteinuria and glomerular hypercellularity did not develop, whereas these features of glomerulonephritis were found in the TMPD-treated WT controls. The clinical and serologic manifestations observed in TMPD-treated mice were strongly dependent on IFNAR signaling, which is consistent with the association of increased expression of ISGs with lupus-specific autoantibodies and nephritis in humans. Similar to its proposed role in human SLE, signaling via the IFNAR is central to the pathogenesis of autoantibodies and glomerulonephritis in TMPD-induced lupus. This lupus model is the first animal model shown to recapitulate the "interferon signature" in peripheral blood.

The Role of Apoptosis in the Ameliorating Effects of a CDR1-Based Peptide on Lupus Manifestations in a Mouse Model

Experimental systemic lupus erythematosus (SLE) can be induced in mice following immunization with an anti-DNA mAb expressing a major Id, 16/6Id. Treatment with a peptide, designated human CDR1 (hCDR1; Edratide), that is based on the sequence of CDR1 of the 16/6Id ameliorated disease manifestations. In the present study, we investigated the roles of apoptosis and related molecules in BALB/c mice with induced experimental SLE following treatment with hCDR1. A higher state of activation and increased rate of apoptosis were found in lymphocytes of SLE-afflicted mice as compared with healthy controls. The latter effects were associated with up-regulated caspase-8 and caspase-3, and down-regulated Bcl-x(L). The ameliorative effects of hCDR1 were associated with down-regulation of caspase-8 and caspase-3, up-regulation of Bcl-x(L), and a reduced rate of apoptosis. Treatment of diseased mice with an apoptosis-reducing compound that inhibited caspases down-regulated the secretion of the pathogenic cytokine IFN-gamma and lowered the intensity of glomerular immune complex deposits and the levels of proteinuria. Furthermore, coincubation of Bcl-x(L) inhibitors with hCDR1-treated cells abrogated the ability of hCDR1 to reduce the activation state of lymphocytes and to down-regulate the secretion of IL-10 and IFN-gamma. Moreover, the Bcl-x(L)-expressing CD4(+)CD25(+) cells from hCDR1-treated mice induced the expression of Bcl-x(L) in CFSE-labeled CD4(+)CD25(-) cells of the SLE-afflicted mice. Thus, the reduction of apoptosis and the up-regulation of Bcl-x(L), which plays an apparent role in tolerance induction, contribute to at least part of the beneficial effects of hCDR1 on lupus manifestations.