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Biomedical subjects

Michael P Madaio

Publications and source records attributed to Michael P Madaio.

At least 19 recordsLinked to original sources
PubMed2006

Modulation of autoimmunity by TLR9 in the chronic graft-vs-host model of systemic lupus erythematosus.

Chronic graft-vs-host (cGVH) disease is induced in nonautoimmune mice by the transfer of alloreactive T cells that recognize foreign MHC class II. It closely resembles systemic lupus erythematosus, with antinuclear Abs and immune-mediated nephritis. Recent work has implicated TLRs, particularly TLR9, in the recognition of certain autoantigens in vitro and in vivo. To explore further the role of TLR9 in systemic autoimmunity, we induced cGVH disease in C57BL/6 (B6) mice lacking TLR9, including B6 mice expressing the anti-DNA-encoding IgH transgenes 3H9 or 56R (B6.3H9.TLR9(-/-), B6.56R.TLR9(-/-)). We found that cGVH disease caused breakdown of B cell tolerance to chromatin and DNA in TLR9(-/-) recipients of alloreactive cells, yet that nephritis was less severe and that some autoantibody titers were lower compared with B6-cGVH controls. Spleen lymphocyte analysis showed that cGVH disease strikingly depleted marginal zone B cells in B6 mice, but did not influence T cell subsets in either B6 or B6-TLR9(-/-) hosts. B6.56R.TLR9(-/-) mice had less spontaneous production of autoantibodies than B6.56R mice, but there were no significant differences between B6.56R and B6.56R.TLR9(-/-) postinduction of cGVH disease. Taken together, these results suggested that TLR9 may worsen some aspects of systemic autoimmunity while alleviating others.

Animals↗
PubMed2006

DAF/Crry double deficiency in mice exacerbates nephrotoxic serum-induced proteinuria despite markedly reduced systemic complement activity.

Decay-accelerating factor (DAF) and complement receptor 1-related gene/protein y (Crry) are two membrane-anchored complement regulatory proteins in rodent. Although both proteins are broadly distributed and exert complement regulation at the same steps of the complement cascade, DAF knockout mice are viable whereas Crry knockout mice die in utero as a result of maternal complement attack. The latter outcome has prevented the dissection of overlapping functions of DAF and Crry in adult mouse tissues in vivo. By crossing female DAF(-/-)/Crry(-/-)/C3(-/-) mice with male DAF(-/-)/Crry(+/-)/C3(+/-) mice, we circumvented maternal complement attack during fetal development and generated viable DAF(-/-)/Crry(-/-)/C3(+/-) mice to address the consequence of DAF/Crry double deficiency. DAF(-/-)/Crry(-/-)/C3(+/-) mice were born at the expected frequency and survived to adulthood. However, they were found to have greatly reduced systemic complement activity due, at least in part, to spontaneous C3 activation and consumption. Plasma C3 proteins in DAF(-/-)/Crry(-/-)/C3(+/-) mice were 30% of that of wild-type mice, and serum complement activity, as assessed by zymosan and immune complex C3 opsonization assays, was 90% reduced in DAF(-/-)/Crry(-/-)/C3(+/-) mice. Remarkably, despite greatly reduced systemic complement activity, DAF(-/-)/Crry(-/-)/C3(+/-) mice developed more severe proteinuria after induction of nephrotoxic serum nephritis as compared with DAF(-/-)/Crry(+/-)/C3(+/-) and DAF(-/-)/Crry(-/-)/C3(-/-) littermate controls. The results highlight the critical and overlapping role of Crry and DAF in vivo in preventing complement activation and tissue injury.

Animals↗
PubMed2006

Pathology and protection in nephrotoxic nephritis is determined by selective engagement of specific Fc receptors.

Introduction of heterologous anti-glomerular basement membrane antiserum (nephrotoxic serum, NTS) into presensitized mice triggers the production of IgG anti-NTS antibodies that are predominantly IgG2b and the glomerular deposition of pathogenic immune complexes, leading to accelerated renal disease. The pathology observed in this model is determined by the effector cell activation threshold that is established by the coexpression on infiltrating macrophages of the IgG2a/2b restricted activation receptor FcgammaRIV and its inhibitory receptor counterpart, FcgammaRIIB. Blocking FcgammaRIV with a specific monoclonal antibody thereby preventing IgG2b engagement or treatment with high dose intravenous gamma-globulin (IVIG) to down-regulate FcgammaRIV while up-regulating FcgammaRIIB, protects mice from fatal disease. In the absence of FcgammaRIIB, IVIG is not protective; this indicates that reduced FcgammaRIV expression alone is insufficient to protect animals from pathogenic IgG2b immune complexes. These results establish the significance of specific IgG subclasses and their cognate FcgammaRs in renal disease.

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PubMed2005

The mitochondrial and kidney disease phenotypes of kd/kd mice under germfree conditions.

Interstitial nephritis occurs spontaneously in kd/kd mice, but the mechanisms leading to this disease have not been fully elucidated. The earliest manifestation of a phenotype is the appearance of ultrastructural defects in the mitochondria of mice as young as 42 days of age. To examine the influence of the environment on the phenotype, homozygous B6.kd/kd mice were transferred from specific pathogen-free (SPF) conditions to a germfree (GF) environment, and the development of the disease was observed. The GF state resulted in a highly significant reduction in the frequency of tubulointerstitial nephritis. In addition, GF conditions markedly reduced the appearance of the mitochondrial phenotype, with no sign of mitochondrial abnormalities in GF mice of up to 155 days of age. These results suggest that environmental factors are involved in the progression of all known manifestations of this disease phenotype.

Animals↗
PubMed2005

Glomerular and tubular epithelial defects in kd/kd mice lead to progressive renal failure.

BACKGROUND/AIM: The kd/kd mouse spontaneously develops severe and progressive nephritis leading to renal failure, characterized by cellular infiltration, tubular destruction and glomerular sclerosis. Recent identification of the mutant gene and the observation that podocytes are affected, led to the hypothesis that there are primary renal epithelial cell defects in this strain. METHODS: Clinical and pathological signs of disease in a large cohort of kd/kd mice were studied by light microscopy, electron microscopy, and biochemical analyses of serum and urine at early stages of disease. Special attention was paid to mice under 140 days of age that had normal blood urea nitrogen (BUN) levels, but had developed albuminuria. RESULTS: Although overt glomerular abnormalities are commonly observed either coincident with or after tubulointerstitial nephritis, we now report that albuminuria and visceral epithelial abnormalities, including hyperplasia and podocyte effacement may occur before the onset of either elevated BUN levels or severe interstitial nephritis, and this is accompanied by biochemical perturbations in serum typical of the nephrotic syndrome. CONCLUSIONS: The results suggest that the defect in kd/kd mice primarily affects both the tubular and glomerular visceral epithelium. The tubular epithelial defect triggers autoimmune interstitial nephritis, whereas a defect in podocytes leads to proteinuria and glomerulosclerosis. Thus, a single mitochondrial abnormality may result in differences in disease expression that vary with the type of epithelial cells. It is likely that the mitochrondrial perturbations in glomerular and tubular epithelia act in concert, through activation of different pathologic pathways, to accelerate disease progression leading to renal failure.

Animals↗
PubMed2005

The kd/kd mouse is a model of collapsing glomerulopathy.

Collapsing glomerulopathy (CG) is associated with disorders that markedly perturb the phenotype of podocytes. The kd/kd mouse has been studied for immune and genetic causes of microcystic tubulointerstitial nephritis with little attention to its glomerular lesion. Because histologic examination revealed classic morphologic features of CG, the question arises whether podocytes in kd/kd mice exhibit additional phenotypic criteria for CG. Utilizing Tg26 mice as a positive control, immunohistochemical profiling of the podocyte phenotype was conducted simultaneously on both models. Similar to Tg26 kidneys, podocytes in kd/kd kidneys showed de novo cyclin D1, Ki-67, and desmin expression with loss of synaptopodin and WT-1 expression. Electron micrographs showed collapsed capillaries, extensive foot process effacement, and dysmorphic mitochondria in podocytes. These results indicate that the kd/kd mouse is a model of CG and raise the possibility that human equivalents of the kd susceptibility gene may exist in patients with CG.

Animals↗
PubMed2005

Nuclear localizing anti-DNA antibodies enter cells via caveoli and modulate expression of caveolin and p53.

After administration to normal mice, a subset of monoclonal (m) anti-DNA antibodies (Ab) derived from MRL-lpr/lpr mice was identified that enter cells, in vivo. In the kidneys, this was associated with glomerular hypercellularity and proteinuria. In cultured cells, the same mAb bound to myosin 1 on the cell surface, prior to internalization, nuclear localization and inhibition of apoptosis. The present study focuses on the mechanisms underlying the observed functional effects. Subcellular localization studies revealed that following internalization, a prototypic, nuclear localizing, m antibody (Ab; termed H7) co-localized with myosin 1, shortly after internalization, within caveolae, near the cell membrane. Cell fractionation studies confirmed the presence of both H7 and myosin within the caveolar fraction. Since variations in caveolin protein expression have been associated with apoptotic events in cancer cells, through p53 dependent and independent pathways, modulation of caveolin by intracellular H7 was evaluated. Cellular entry of the anti-DNA Ab resulted in an increase in caveolin protein expression. Furthermore, after exposure of cells to dexamethasone to induce apoptosis, the usual increase in p53 was inhibited in the presence of intracellular H7. Taken together, the results suggest that upregulation of caveolin and inhibition of p53 induction are involved in H7-induced, inhibition of apoptosis. Furthermore, they suggest that this inhibition contributes to the glomerular hypercellularity observed in normal mice with intranuclear H7. The results also raise the possibility that inhibition of apoptotic pathways during inflammation or/and autoimmunity could influence subsequent disease events. The novel mechanism of cellular perturbation is indirect and dependent on apoptotic stimuli, and it may account for the presence of intranuclear antibodies in inflammatory and normal tissues of individuals with lupus.

Adenosine Triphosphate↗
PubMed2004

Mechanism of action of transmembrane activator and calcium modulator ligand interactor-Ig in murine systemic lupus erythematosus.

B cell-activating factor belonging to the TNF family (BAFF) blockade prevents the onset of disease in systemic lupus erythematosus (SLE)-prone NZB/NZW F(1) mice. To determine the mechanism of this effect, we administered a short course of TACI-Ig with and without six doses of CTLA4-Ig to 18- to 20-wk-old NZB/NZW F(1) mice and evaluated the effect on B and T cell subsets and on anti-dsDNA Ab-producing B cells. Even a brief exposure to TACI-Ig had a beneficial effect on murine SLE; CTLA4-Ig potentiated this effect. The combination of TACI-Ig and CTLA4-Ig resulted in a temporary decrease in serum IgG levels. However, after cessation of treatment, high titers of IgG anti-dsDNA Abs appeared in the serum and IgG Abs deposited in the kidneys. Despite the appearance of pathogenic autoantibodies, the onset of proteinuria was markedly delayed; this was associated with prolonged depletion of B cells past the T1 stage, a decrease in the size of the spleen and lymph nodes, and a decrease in the absolute number of activated and memory CD4(+) T cells. TACI-Ig treatment normalized serum levels of IgM that are markedly elevated in NZB/W F(1) mice; this appeared to be due to a prolonged effect on the ability of the splenic microenvironment to support short-lived IgM plasma cells. Finally, a short course of combination TACI-Ig and CTLA4-Ig prolonged life and even reversed proteinuria in aged NZB/W F(1) mice, suggesting that BAFF blockade may be an effective therapeutic strategy for active SLE.

Abatacept↗
PubMed2004

Isolation, culture, and characterization of endothelial cells from mouse glomeruli.

BACKGROUND: Cloned glomerular endothelial cells (GENC) have many potential uses and applications in immunologic and physiologic studies. Propagation of GENC has been difficult and available homogeneous GENC, particularly from mice, are limited. Herein we report isolation, cloning, propagation, and characterization of GENC from mice. METHODS: tsA58 immorto mice were used to isolate glomerular cells. Glomeruli were isolated by differential sieving, and decapsulated explants were cultured in permissive and optimal conditions for endothelial cells. The primary cells from glomerular outgrowths were expanded, taking advantage of the temperature-sensitive tsA58 gene, and then the cells were allowed to undergo spontaneous transformation. The cells were then sorted using anti-CD31 antibodies and their capacity to uptake acetylated-low-density lipoprotein (LDL). Individual subclones isolated by patch cloning were characterized using multiple markers. RESULTS: One of the homogeneous clones was morphologically endothelial-like, positive for CD31, CD106, CD62E, CD54, and acetylated-LDL uptake, formed tubes, and was negative for epithelial and mesangial cell markers. The functional properties of this GENC clone appeared to be intact, and signaling pathway was not altered. Two of the clones displayed the characteristics of either visceral epithelial or mesangial cells. CONCLUSION: The identified clones should have utility in multiple areas of investigation.

Animals↗
PubMed2004

Mutant prenyltransferase-like mitochondrial protein (PLMP) and mitochondrial abnormalities in kd/kd mice.

BACKGROUND: Mice that are homozygous for the kidney disease (kd) mutation are apparently healthy for the first 8 weeks of life, but spontaneously develop a severe form of interstitial nephritis that progresses to end-stage renal disease (ESRD) by 4 to 8 months of age. By testing for linkage to microsatellite markers, we previously localized the kd gene to a YAC/BAC contig. METHODS: The sequence of the entire critical region was examined, and candidate genes were identified. These candidate genes were sequenced in both mutant (kd/kd) mice and normal controls. The phenotype was further characterized by immunohistochemistry and electron microscopy. Transgenic mice were constructed that carried the wild-type allele of the prime candidate gene, and this transgene was transferred to a kd/kd background by breeding. RESULTS: We have obtained evidence that kd is a mutant allele of a novel gene for a prenyltransferase-like mitochondrial protein (PLMP). This gene is alternatively spliced, with the larger gene product having one domain that resembles transprenyltransferase and another that is similar to geranylgeranyl pyrophosphate synthase. The smaller gene product includes only the first domain. An antiserum to PLMP localizes to mitochondria, and ultrastructural defects are present in the mitochondria of renal tubular epithelial cells, and to a lesser extent, hepatocytes and heart cells from kd/kd mice. In a line of kd/kd mice that carried the wild-type PLMP allele as a transgene, only 1 out of 13 animals expressed the disease by 120 days of age. CONCLUSION: The kd allele codes for a novel protein that localizes to the mitochondria, and the kd/kd mouse has dysmorphic mitochondria in the renal tubular epithelial cells. This mouse is therefore a unique animal model for studying mechanisms that lead to tubulointerstitial nephritis.

Amino Acid Sequence↗
PubMed2003

Cutting Edge: Multiple autoimmune pathways in kd/kd mice.

The kidney disease (kd) mutation was transferred to a C57BL/6 (B6) background by selection for closely linked microsatellite markers. The resulting congenic strain, B6.kd, was mated with partners homozygous for targeted mutations of CD4, CD8, CD28, IL-2, recombinase-activating gene-1 (Rag-1), ICAM-1, or beta(2)-microglobulin. In most of the resulting double mutants, kidney disease occurred as readily and as severely as in the B6.kd controls, although disease occurred somewhat less frequently in age-matched CD28(-/-) kd/kd mice. Immunohistology demonstrated a predominance of macrophages in the lesions of B6.kd and most of the double mutants, with the remaining cells consisting of T cells and variable numbers of NK cells. In Rag-1(-/-) kd/kd, approximately 50% of infiltrating cells were macrophages, and approximately 50% were NK cells. These results suggest that the initial lesion caused by the mutant gene is intrinsic to the kidney and that the immune response that subsequently occurs can involve any one of several different cellular compositions.

Animals↗
PubMed2003

Short term administration of costimulatory blockade and cyclophosphamide induces remission of systemic lupus erythematosus nephritis in NZB/W F1 mice by a mechanism downstream of renal immune complex deposition.

NZB/W F(1) mice with established nephritis were treated with a single dose of cyclophosphamide with or without a 2-wk course of murine CTLA4Ig, either alone or in combination with anti-CD154. Sixty to 80% of treated mice entered remission, and remission could be reinduced following relapse. A decrease in the frequency of anti-DNA-producing B cells and activated T cells was observed in treated mice, but this effect lasted only 3-6 wk, while remissions were sustained for up to 20 wk. Light microscopy of the kidneys of mice in remission revealed less glomerular inflammation, less tubular damage, and less infiltration of inflammatory cells. By immunofluorescence, however, IgG and C3 staining of glomeruli was no different in treated mice vs controls. Since chemokines and their receptors play an important role in inflammatory cell infiltration of affected organs in autoimmune diseases, we examined chemokine expression in the kidneys. Decreases in the expression of inflammatory cytokines and chemokines were evident in mice in the early stages of remission, but these differences were no longer present in late remission. Increased expression of CXCL13 was detected in the inflammatory infiltrates of the control NZB/NZW mice. Strikingly, we could not detect any CXCL13 in the kidneys of the treated group even in late remission. These findings suggest that costimulatory blockade together with cyclophosphamide influence the activation state of renal CD11c-positive cells and therefore lead to less B and T cell infiltration and nephritis.

Abatacept↗
PubMed2003

The role of antibodies and B cells in the pathogenesis of lupus nephritis.

Nephritis occurs commonly in lupus patients, and many immunological and nonimmunological factors contribute to disease expression. It is generally appreciated that glomerular immune deposit formation is an early and initiating event, although the mechanisms leading to the deposition of nephritogenic antibodies continue to be debated. Furthermore, it has recently become evident that autoantibodies expressed on B cells also play an important role in pathogenesis. This review focuses on the properties of nephritogenic autoantibodies, their mechanisms of immune deposit formation, and the contribution of B cells expressing autoantibodies to lupus nephritis.

Animals↗
PubMed2003

Recent advances in the pathogenesis of lupus nephritis: autoantibodies and B cells.

Although many factors contribute to the clinical presentation and subsequent course of individuals with lupus nephritis, the formation of glomerular immune deposits is typically one of the initial events. In general, breakdown in immunologic tolerance leads to the production of autoreactive B and T cells that, either through direct infiltration and/or their secretory products, initiate inflammation. Immune deposition within glomeruli results in complement activation and recruitment of inflammatory cells, along with activation of endogenous renal cells. This inflammatory cascade leads to secretion of cytokines and chemokines, which in turn attract more infiltrating cells. Up-regulation of lymphoid-derived chemokines further enhance the cellular influx, augmenting inflammation and resulting in further tissue damage. The degree of inflammation is determined by the extent of this invasion along with both the systemic and local responses to the assault. This review focuses mainly on the contributions of pathogenic autoantibodies, autoreactive B cells to lupus nephritis, and potential immunologic therapies for lupus nephritis. Manipulation of both the cells and soluble mediators that initiate and perpetuate the disease are essential to suppressing autoreactivity and inflammation and preventing disease progression.

Animals↗
PubMed2003

Lifespan is prolonged in autoimmune-prone (NZB/NZW) F1 mice fed a diet supplemented with indole-3-carbinol.

Dietary modulation has the potential to prevent or ameliorate systemic lupus erythematosus (SLE). Indole-3-carbinol (I3C), which is abundant in cruciferous vegetables, was evaluated in a murine model of SLE because of its antiestrogenic activities. Female (NZB x NZW) F1 mice, which develop SLE, were fed an AIN76A diet without or with 0.2 g/kg I3C, starting soon after weaning or at 5 mo of age. At 12 mo of age, 80% of mice fed the I3C-supplemented diet soon after weaning were alive compared with only 10% of controls. When experimental diets were initiated at 5 mo of age, 100% of I3C fed mice and 30% of controls were alive at 12 mo of age. Anti-double-stranded DNA (dsDNA) antibodies developed in all groups, although at several time points, the levels produced in I3C-fed mice were significantly lower. Renal disease (proteinuria, histologic changes, IgG immune complex deposition, subepithelial deposits and diffuse epithelial cell foot process effacement) was more severe in controls with both protocols. The estrogen urinary metabolite ratio of 2- to 16alpha-hydroxyestrone was increased in I3C-fed mice. These findings demonstrate a profound effect of dietary I3C in experimental SLE.

Animals↗
PubMed2002

IL-10 regulates murine lupus.

MRL/MpJ-Tnfrsf6(lpr) (MRL/MpJ-Fas(lpr); MRL-Fas(lpr)) mice develop a spontaneous lupus syndrome closely resembling human systemic lupus erythematosus. To define the role of IL-10 in the regulation of murine lupus, IL-10 gene-deficient (IL-10(-/-)) MRL-Fas(lpr) (MRL-Fas(lpr) IL-10(-/-)) mice were generated and their disease phenotype was compared with littermates with one or two copies of an intact IL-10 locus (MRL-Fas(lpr) IL-10(+/-) and MRL-Fas(lpr) IL-10(+/+) mice, respectively). MRL-Fas(lpr) IL-10(-/-) mice developed severe lupus, with earlier appearance of skin lesions, increased lymphadenopathy, more severe glomerulonephritis, and higher mortality than their IL-10-intact littermate controls. The increased severity of lupus in MRL-Fas(lpr) IL-10(-/-) mice was closely associated with enhanced IFN-gamma production by both CD4(+) and CD8(+) cells and increased serum concentration of IgG2a anti-dsDNA autoantibodies. The protective effect of IL-10 in this lupus model was further supported by the observation that administration of rIL-10 reduced IgG2a anti-dsDNA autoantibody production in wild-type MRL-Fas(lpr) animals. In summary, our results provide evidence that IL-10 can down-modulate murine lupus through inhibition of pathogenic Th1 cytokine responses. Modulation of the level of IL-10 may be of potential therapeutic benefit for human lupus.

Animals↗
PubMed2002

Chronic graft-versus-host in Ig knockin transgenic mice abrogates B cell tolerance in anti-double-stranded DNA B cells.

Anti-dsDNA Abs are specific diagnostic markers of systemic lupus erythematosus, and are also implicated in kidney pathology. Anti-dsDNA B cells have been shown to be tolerized in nonautoimmune mice. The immunodysregulation that causes these cells to break tolerance is presumably part of the fundamental defects in systemic lupus erythematosus. To explore these mechanisms, we used the chronic graft-versus-host model mediated by MHC class II differences. Induction of chronic graft-vs-host in anti-DNA H chain knockin (3H9.KI) transgenic mice on a nonautoimmune background resulted in specific activation of anti-dsDNA B cells, as evidenced by high titers of soluble Ab in sera and a high frequency (70%) of anti-dsDNA B cell clones recovered as hybridomas. In addition, the lambda(+)-anti-dsDNA B cells developed increased expression of cell surface activation markers, and concentrated in the T cell area of the follicle with an Ab-forming cell-compatible phenotype. Genetic analysis of the hybridoma clones showed strong evidence of secondary rearrangements of the L chain associated with anti-dsDNA reactivity. Thus, our study indicates that alloreactive T cell help can break tolerance in a complex manner, involving several events.

Animals↗