Autoantibodies against the cell surface-associated chaperone GRP78 stimulate tumor growth via tissue factor

Tumor cells display on their surface several molecular chaperones that normally reside in the endoplasmic reticulum. Because this display is unique to cancer cells, these chaperones are attractive targets for drug development. Previous epitope-mapping of autoantibodies (AutoAbs) from prostate cancer patients identified the 78-kDa glucose-regulated protein (GRP78) as one such target. Although we previously showed that anti-GRP78 AutoAbs increase tissue factor (TF) procoagulant activity on the surface of tumor cells, the direct effect of TF activation on tumor growth was not examined. In this study, we explore the interplay between the AutoAbs against cell surface-associated GRP78, TF expression/activity, and prostate cancer progression. First, we show that tumor GRP78 expression correlates with disease stage and that anti-GRP78 AutoAb levels parallel prostate-specific antigen concentrations in patient-derived serum samples. Second, we demonstrate that these anti-GRP78 AutoAbs target cell-surface GRP78, activating the unfolded protein response and inducing tumor cell proliferation through a TF-dependent mechanism, a specific effect reversed by neutralization or immunodepletion of the AutoAb pool. Finally, these AutoAbs enhance tumor growth in mice bearing human prostate cancer xenografts, and heparin derivatives specifically abrogate this effect by blocking AutoAb binding to cell-surface GRP78 and decreasing TF expression/activity. Together, these results establish a molecular mechanism in which AutoAbs against cell-surface GRP78 drive TF-mediated tumor progression in an experimental model of prostate cancer. Heparin derivatives counteract this mechanism and, as such, represent potentially appealing compounds to be evaluated in well-designed translational clinical trials.

Generation and characterization of function-blocking anti-ectodysplasin A (EDA) monoclonal antibodies that induce ectodermal dysplasia

Development of ectodermal appendages, such as hair, teeth, sweat glands, sebaceous glands, and mammary glands, requires the action of the TNF family ligand ectodysplasin A (EDA). Mutations of the X-linked EDA gene cause reduction or absence of many ectodermal appendages and have been identified as a cause of ectodermal dysplasia in humans, mice, dogs, and cattle. We have generated blocking antibodies, raised in Eda-deficient mice, against the conserved, receptor-binding domain of EDA. These antibodies recognize epitopes overlapping the receptor-binding site and prevent EDA from binding and activating EDAR at close to stoichiometric ratios in in vitro binding and activity assays. The antibodies block EDA1 and EDA2 of both mammalian and avian origin and, in vivo, suppress the ability of recombinant Fc-EDA1 to rescue ectodermal dysplasia in Eda-deficient Tabby mice. Moreover, administration of EDA blocking antibodies to pregnant wild type mice induced in developing wild type fetuses a marked and permanent ectodermal dysplasia. These function-blocking anti-EDA antibodies with wide cross-species reactivity will enable study of the developmental and postdevelopmental roles of EDA in a variety of organisms and open the route to therapeutic intervention in conditions in which EDA may be implicated.

Effects of the ß2-adrenoceptor agonist, albuterol, in a mouse model of anti-MuSK myasthenia gravis

The β2-adrenergic receptor agonist, albuterol, has been reported beneficial in treating several forms of congenital myasthenia. Here, for the first time, we examined the potential benefit of albuterol in a mouse model of anti-Muscle Specific Kinase (MuSK) myasthenia gravis. Mice received 15 daily injections of IgG from anti-MuSK positive patients, which resulted in whole-body weakness. At neuromuscular junctions in the tibialis anterior and diaphragm muscles the autoantibodies caused loss of postsynaptic acetylcholine receptors, and reduced the amplitudes of the endplate potential and spontaneous miniature endplate potential in the diaphragm muscle. Treatment with albuterol (8 mg/kg/day) during the two-week anti-MuSK injection series reduced the degree of weakness and weight loss, compared to vehicle-treated mice. However, the compound muscle action potential recorded from the gastrocnemius muscle displayed a decremental response in anti-MuSK-injected mice whether treated with albuterol or vehicle. Ongoing albuterol treatment did not increase endplate potential amplitudes compared to vehicle-treated mice nor did it prevent the loss of acetylcholine receptors from motor endplates. On the other hand, albuterol treatment significantly reduced the degree of fragmentation of endplate acetylcholine receptor clusters and increased the extent to which the remaining receptor clusters were covered by synaptophysin-stained nerve terminals. The results provide the first evidence that short-term albuterol treatment can ameliorate weakness in a robust mouse model of anti-MuSK myasthenia gravis. The results also demonstrate that it is possible for albuterol treatment to reduce whole-body weakness without necessarily reversing myasthenic impairment to the structure and function of the neuromuscular junction.

Anti-heat shock protein 70 autoantibody epitope changes and BD091 promotes atherosclerosis in rats

It has been previously reported that the plasma levels of autoantibodies against heat shock protein 70 (HSP70) are elevated in atherosclerosis. The aim of the present study was to elucidate whether anti-HSP70 antibodies are involved in the pathogenesis of atherosclerosis. To determine this, we chose rats as an atherosclerosis model. Titers of plasma anti-HSP70 autoantibody were determined by ELISA. After the intravenous administration of antibody into the tail, the damaged areas of aorta were stained with Evans Blue, atheromatous plaque were stained by Oil Red O, and then they were measured and quantified with AxioVision computer software. The number of macrophages ([Formula: see text]), smooth muscle cells (SMCs), and T cells were determined by immunocytochemistry. The level of anti-HSP70 IgG1 antibody was apparently increased in the AS group at the tenth week, and one hybridoma of HSP70 antibody (BD091, IgG1, recognizing C-terminal) had the same binding epitope as plasma anti-HSP70 autoantibodies. After intravenous administration, the lesion area of aorta with BD091 was significantly larger than those of IgG(mouse) and SPA-810. Moreover, injection of BD091 resulted in significant endothelium damage, followed by a greater accumulation of [Formula: see text], T cells, and SMCs in lesions than in the control. In conclusion, BD091 reaction with HSP70 expressed on arterial endothelial cells inducing endothelium damage triggers the inflammatory response in the vessel wall that accelerates atherosclerosis in rats. BD091 shares the same binding epitope with HSP70 autoantibodies. These data indicated that a specific epitope of anti-HSP70 autoantibody participated in the pathogenesis of atherosclerosis.

Neurotoxic lupus autoantibodies alter brain function through two distinct mechanisms

Damaging interactions between antibodies and brain antigenic targets may be responsible for an expanding range of neurological disorders. In the case of systemic lupus erythematosus (SLE), patients generate autoantibodies (AAbs) that frequently bind dsDNA. Although some symptoms of SLE may arise from direct reactivity to dsDNA, much of the AAb-mediated damage originates from cross-reactivity with other antigens. We have studied lupus AAbs that bind dsDNA and cross-react with the NR2A and NR2B subunits of the NMDA receptor (NMDAR). In adult mouse models, when the blood-brain barrier is compromised, these NMDAR-reactive AAbs access the brain and elicit neuronal death with ensuing cognitive dysfunction and emotional disturbance. The cellular mechanisms that underlie these deleterious effects remain incompletely understood. Here, we show that, at low concentration, the NMDAR-reactive AAbs are positive modulators of receptor function that increase the size of NMDAR-mediated excitatory postsynaptic potentials, whereas at high concentration, the AAbs promote excitotoxicity through enhanced mitochondrial permeability transition. Other synaptic receptors are completely unaffected by the AAbs. NMDAR activation is required for producing both the synaptic and the mitochondrial effects. Our study thus reveals the mechanisms by which NMDAR-reactive AAbs trigger graded cellular alterations, which are likely to be responsible for the transient and permanent neuropsychiatric symptoms observed in patients with SLE. Our study also provides a model in which local AAb concentration determines the exact nature of the cellular response.

Patient autoantibodies deplete postsynaptic muscle-specific kinase leading to disassembly of the ACh receptor scaffold and myasthenia gravis in mice

The postsynaptic muscle-specific kinase (MuSK) coordinates formation of the neuromuscular junction (NMJ) during embryonic development. Here we have studied the effects of MuSK autoantibodies upon the NMJ in adult mice. Daily injections of IgG from four MuSK autoantibody-positive myasthenia gravis patients (MuSK IgG; 45 mg day(1)i.p. for 14 days) caused reductions in postsynaptic ACh receptor (AChR) packing as assessed by fluorescence resonance energy transfer (FRET). IgG from the patients with the highest titres of MuSK autoantibodies caused large (51-73%) reductions in postsynaptic MuSK staining (cf. control mice; P < 0.01) and muscle weakness. Among mice injected for 14 days with control and MuSK patient IgGs, the residual level of MuSK correlated with the degree of impairment of postsynaptic AChR packing. However, the loss of postsynaptic MuSK preceded this impairment of postsynaptic AChR. When added to cultured C2 muscle cells the MuSK autoantibodies caused tyrosine phosphorylation of MuSK and the AChR beta-subunit, and internalization of MuSK from the plasma membrane. The results suggest a pathogenic mechanism in which MuSK autoantibodies rapidly deplete MuSK from the postsynaptic membrane leading to progressive dispersal of postsynaptic AChRs. Moreover, maintenance of postsynaptic AChR packing at the adult NMJ would appear to depend upon physical engagement of MuSK with the AChR scaffold, notwithstanding activation of the MuSK-rapsyn system of AChR clustering.

Immunologic and neurodevelopmental susceptibilities of autism

Symposium 5 focused on research approaches that are aimed at understanding common patterns of immunological and neurological dysfunction contributing to neurodevelopmental disorders such as autism and ADHD. The session focused on genetic, epigenetic, and environmental factors that might act in concert to influence autism risk, severity and co-morbidities, and immunological and neurobiological targets as etiologic contributors. The immune system of children at risk of autism may be therefore especially susceptible to psychological stressors, exposure to chemical triggers, and infectious agents. Identifying early biomarkers of risk provides tangible approaches toward designing studies in animals and humans that yield a better understanding of environmental risk factors, and can help identify rational intervention strategies to mitigate these risks.

Pemphigus vulgaris and its active disease mouse model

Pemphigus is an autoimmune disease of the skin and mucous membranes and is mediated by IgG autoantibodies against desmoglein (Dsg), a cadherin-type cell-cell adhesion molecule in desmosomes. Recently, an active disease mouse model of pemphigus vulgaris (PV) was generated with a unique approach using autoantigen knockout mice, in which selftolerance of the defective gene product is not acquired. This approach included the adoptive transfer of Dsg3-/- lymphocytes to Rag2-/- immunodeficient mice that express Dsg3- induced stable production of pathogenic anti-Dsg3 IgG for over 6 months and the phenotype of PV including oral erosion with the typical histology in recipient mice. Subsequently, AK and NAK series of anti-Dsg3 IgG monoclonal antibodies were developed from the PV model mice. These monoclonal antibodies showed pathogenic heterogeneity in blister formation, which is, at least in part, explained by their epitopes, and synergistic pathogenic effects by combining several monoclonal antibodies reacting in different parts of the molecule. Although this model does not reflect the actual triggers of autoimmune diseases, it does provide a means to investigate the roles of T and B lymphocytes in perpetuating autoantibody production and to clarify unsolved immunological mechanisms in the autoimmune diseases.

Interaction of giant phospholipid vesicles containing cardiolipin and cholesterol with beta2-glycoprotein-I and anti-beta2-glycoprotein-I antibodies

Antiphospholipid syndrome is characterized with thrombotic events and/or pregnancy morbidity and antiphospholipid antibodies (aPL). The most common antigen for aPL is beta2-glycoprotein-I (beta(2)GPI), a plasma protein binding to negatively charged phospholipids. The influence of aPL on coagulation is not well understood. Giant phospholipid vesicles (GPVs) are a convenient in vitro system for studying interactions between phospholipid membranes and proteins resulting in the change of the vesicles' configuration. We aimed to set up an in vitro model and to study changes in the morphology of GPVs with high content of cardiolipin upon addition of beta(2)GPI and/or IgG fraction of a patient with antiphospholipid syndrome (APS). Addition of the IgG fraction of the APS patient caused lateral segregation of the membrane inclusions and adhesion of GPVs. Addition of beta(2)GPI caused adhesion of GPVs. Addition of both, the patient IgG fraction and beta(2)GPI caused adhesion of vesicles to the glass slides and to each other, formation of pores and burst of vesicles. Our results indicate that adhesion of the cardiolipin-containing vesicles does not seem specific for added proteins, rather, it indicates electrostatic and curvature-mediated interactions between the membrane constituents.

Human antibodies induce arthritis in mice deficient in the low-affinity inhibitory IgG receptor Fc gamma RIIB

Rheumatoid arthritis (RA) is a complex autoimmune disease with a poorly understood pathogenesis. The disease is associated with polyclonal B cell activation and the production of autoantibodies (autoAbs), but there is a longstanding controversy as to whether such Abs contribute to, or are secondary to, the pathogenesis of RA. To address the potential pathogenicity of human RA–associated Abs, we developed a passive transfer model involving mice deficient in the low-affinity inhibitory Fc receptor, FcγRIIB. We report that plasma or serum from patients with active RA can induce inflammation and histological lesions in FcγRIIB^−/− mice consistent with arthritis, and that this pathogenic activity is caused by the immunoglobulin G–rich fraction. Our results suggest that humoral autoimmunity can contribute directly to autoimmune arthritis, and that FcγRIIB^−/− mice are a promising model to evaluate the arthritogenic potential of human autoAbs.

Anti-disialosyl antibodies mediate selective neuronal or Schwann cell injury at mouse neuromuscular junctions

The human paralytic neuropathy, Miller Fisher syndrome (MFS) is associated with autoantibodies specific for disialosyl epitopes on gangliosides GQ1b, GT1a, and GD3. Since these gangliosides are enriched in synaptic membranes, anti-ganglioside antibodies may target neuromuscular junctions (NMJs), thereby contributing to disease symptoms. We have shown previously that at murine NMJs, anti-disialosyl antibodies induce an alpha-latrotoxin-like effect, electrophysiologically characterized by transient massive increase of spontaneous neurotransmitter release followed by block of evoked release, resulting in paralysis of the muscle preparation. Morphologically, motor nerve terminal damage, as well as perisynaptic Schwann cell (pSC) death is observed. The relative contributions of neuronal and pSC injury to the paralytic effect and subsequent repair are unknown. In this study, we have examined the ability of subsets of anti-disialosyl antibodies to discriminate between the neuronal and glial elements of the NMJ and thereby induce either neuronal injury or pSC death. Most antibodies reactive with GD3 induced pSC death, whereas antibody reactivity with GT1a correlated with the extent of nerve terminal injury. Motor nerve terminal injury resulted in massive uncontrolled exocytosis with paralysis. However, pSC ablation induced no acute (within 1 h) electrophysiological or morphological changes to the underlying nerve terminal. These data suggest that at mammalian NMJs, acute pSC injury or ablation has no major deleterious influence on synapse function. Our studies provide evidence for highly selective targeting of mammalian NMJ membranes, based on ganglioside composition, that can be exploited for examining axonal-glial interactions both in disease states and in normal NMJ homeostasis.

The exploration of joint-specific immunoreactions on immunoglobulins G of anti-glucose-6-phosphate isomerase antibody-positive patients with rheumatoid arthritis

The pathogenic role of autoantibodies in rheumatoid arthritis (RA) remains elusive. Anti-glucose-6-phosphate isomerase (GPI) antibodies (Abs) are candidates for arthritogenic Abs because they directly induce arthritis in mice. High titers of anti-GPI Abs are found in some RA patients with severe forms. The aim of this study was to analyze the role of IgG, including anti-GPI Abs, in the joints of RA patients. Synovial tissue was obtained from 6 patients with RA (3 anti-GPI Abs- positive and 3 anti-GPI Abs- negative) and compared histologically and immunohistochemically for IgG and C3 deposition. IgG fractions were separated from the sera of anti-GPI Abs-positive RA patients and healthy subjects, and injected into the metacarpophalangeal joints of 4 cynomolgus monkeys. On day 16, the joints were harvested and examined histologically and immunohistochemically. The expression of the C5a receptor (C5aR) molecule in the synovium was quantified by real-time PCR using cDNA from the monkeys' joints. The synovia of anti-GPI Abs-positive RA patients showed diffuse infiltration of cells, including mast cells, and strong deposition of IgG and C3. In monkeys, IgG from RA patients, including anti-GPI Abs, resulted in recruitment of granulocytes and mononuclear cells, strong deposition of IgG on the articular surface, and overexpression of C5aR, but no joint swelling. No infiltrated cells or IgG deposition were observed in monkeys injected with IgGs from healthy subjects. Our results suggest that IgG fraction from RA patients, including that of anti-GPI Abs, may play a role in the synovitis of RA, although the pathogenesis of human anti-GPI Abs is still uncertain.

Immunization with the glutamate receptor-derived peptide GluR3B induces neuronal death and reactive gliosis, but confers partial protection from pentylenetetrazole-induced seizures

Do autoantibodies (Ab's) against glutamate/AMPA receptor subtype 3 affect the severity of seizures? Rats immunized with the GluR3B-peptide (amino acids (aa) 372-395) or with the control GluR3A-peptide (aa 245-274) produced the respective anti-GluR3B and anti-GluR3A Ab's (both types of Ab's found in some epilepsy patients). The GluR3B-immunized rats exhibited neuronal death and reactive gliosis in the brain, but not overt spontaneous seizures. Surprisingly, in response to the chemoconvulsant pentylenetetrazole, the GluR3B-immunized rats displayed fewer jerks, a lower percentage of generalized seizures, and a lower overall seizure-severity score than GluR3A-immunized, scrambled GluR3B-immunized or non-immunized control rats. These findings, combined with the previously demonstrated ability of anti-GluR3B Ab's to bind, activate, and kill neurons and glia, suggest that if these Ab's are present in the brain they may cause neuronal death, which by itself may be pro-epileptic, but they may also decrease the excitability of seizure-related neural circuits, thereby conferring partial protection from seizures induced by other exogenously applied epileptogenic stimuli. The present results could have clinical implications for epilepsy.

Efficient promotion of collagen antibody induced arthritis (CAIA) using four monoclonal antibodies specific for the major epitopes recognized in both collagen induced arthritis and rheumatoid arthritis

An antibody response to defined epitopes located on the triple helical portion of type II collagen (CII) is associated with the development of collagen-induced arthritis (CIA) and rheumatoid arthritis (RA). Monoclonal antibodies to epitopes associated with arthritis, but not antibodies specific for epitopes not associated with arthritis, induce arthritis in mice, the so-called collagen antibody induced arthritis (CAIA) model. We have selected monoclonal IgG antibodies specific for four well-defined major epitopes on triple helical CII, the C1, J1, D3 and U1 epitopes. These antibodies bind the epitopes specifically as determined using recombinant or synthetic triple helical epitopes. They are encoded from somatically mutated V genes. They all bind cartilage in vivo in normal mice. All of the antibodies induce mild arthritis after injection intravenously and if injected as a cocktail they induce severe clinical arthritis. Intravenous injection of a total of 4 mg antibodies (0.5 mg antibodies per clone) induced arthritis in several different mouse strains without any secondary immune stimulus and intraperitoneal injection of LPS 7 days later dramatically raised the severity. Thus, this method is recommended as a new protocol for the induction of CAIA.

Concanavalin A inhibits pathophysiological effects of anti-ganglioside GQ1b antibodies at the mouse neuromuscular synapse

Anti-GQ1b antibodies are present in the Miller Fisher syndrome (MFS), a monophasic neuropathy characterized by ataxia, areflexia, ophthalmoplegia, and sometimes cranial muscle weakness. We have previously shown, at the mouse neuromuscular junction (NMJ) ex vivo, that anti-GQ1b antibodies, through complement classic pathway activation, block synaptic transmission in a way that resembles the effect of the pore-forming alpha-latrotoxin (alphaLTx). In order to clarify the mechanism of these alphaLTx-like effects, including possible involvement of the alternative and mannose-binding protein complement pathways, we studied the effects of concanavalin A (ConA), a lectin known to block the action of alphaLTx, immunoglobulins, and early complement components. With electrophysiological, immunohistological, and bioassay experiments, we showed that the alphaLTx-like effects of anti-GQ1b antibody and complement were inhibited by pre- and coincubation with ConA. However, ConA was not able to inhibit evolution of alphaLTx-like effects when coincubated upon addition of complement at NMJs that had already bound anti-GQ1b antibody. Our data suggest that the mannose-binding protein pathway is not involved in the alphaLTx-like effect and that the inhibiting effect of ConA principally arises through interference with presynaptic binding of anti-GQ1b antibody. In control experiments, ConA prevented the neuroexocytotic effects of alphaLTx, indicating that alphaLTx receptors were inhibited under these conditions. We conclude that, although the physiological effects at the NMJ of anti-GQ1b antibody and alphaLTx are very similar, the activity of anti-GQ1b antibody is not mediated through activation of alphaLTx receptors, but rather is caused by direct presynaptic membrane damage through classic complement pathway activation.

In vitro keratinocyte dissociation assay for evaluation of the pathogenicity of anti-desmoglein 3 IgG autoantibodies in pemphigus vulgaris

Patients with pemphigus vulgaris (PV) have circulating anti-desmoglein (Dsg) 3 immunoglobulin G (IgG) autoantibodies that induce blister formation. We developed an in vitro quantitative assay to evaluate the pathogenic strength of anti-Dsg3 IgG autoantibodies in blister formation. To obtain intercellular adhesion mediated dominantly by Dsg3, we used primary cultured normal human keratinocytes expressing low level of Dsg2 in the presence of exfoliative toxin A that specifically digests Dsg1. After incubation with various antibodies, monolayers released by dispase were subjected to mechanical stress by pipetting, and the number of cell fragments were counted. When anti-Dsg3 monoclonal antibodies (mAb) obtained from pemphigus model mice were tested, pathogenic AK23 mAb yielded significantly higher number of cell fragments than AK7 or AK20 non-pathogenic mAb. Dissociation scores, defined with AK23 mAb as the positive control, were significantly higher with active stage PV sera (n=10, 77.4+/-21.4) than controls (n=11, 16.0+/-9.6; p=0.003). When pair sera obtained from 6 PV patients in active stage and in remission were compared, the dissociation scores reflected well the disease activity as those in active stage were four to 17 times higher than those in remission. When sera from different patients showing similar ELISA scores but different clinical severity were tested (n=6), the dissociation scores with sera from severe disease activity were significantly higher than those with sera in remission. These findings indicate that this dissociation assay will provide a simple and objective biological method to measure the pathogenic strength of pemphigus autoantibodies.

Evidence that Anti-Type VII Collagen Antibodies Are Pathogenic and Responsible for the Clinical, Histological, and Immunological Features of Epidermolysis Bullosa Acquisita

Epidermolysis bullosa acquisita (EBA) is an autoimmune blistering disease characterized by autoantibodies to type VII (anchoring fibril) collagen. Therefore, it is a prototypic autoimmune disease defined by a well-known autoantigen and autoantibody. In this study, we injected hairless immune competent mice with purified immunoglobulin G (IgG) fraction of serum from rabbits immunized with the non-collagenous amino-terminal domain (NC1) of human type VII collagen, the domain known to contain immunodominant epitopes. As a control, identical mice were injected with the IgG fraction of serum from non-immunized rabbits. Mice injected with immune IgG developed subepidermal skin blisters and erosions, IgG deposits at the epidermal-dermal junction of their skin, and circulating anti-NC1 antibodies in their serum-all features reminiscent of patients with EBA. Similar concentrations of control IgG purified from normal rabbits did not induce disease in the mice. These findings strongly suggest that autoantibodies that recognize human type VII collagen in EBA are pathogenic. This murine model, with features similar to the clinical, histological, and immunological features of EBA, will be useful for the fine dissection of immunopathogenic mechanisms in EBA and for the development of new therapeutic interventions.

Budding, vesiculation and permeabilization of phospholipid membranes—evidence for a feasible physiologic role of β2-glycoprotein I and pathogenic actions of anti-β2-glycoprotein I antibodies

The in vivo physiologic role of beta2-glycoprotein I (beta2GPI) is presumed to be related to its interactions with negatively charged phospholipid membranes. Increased quantities of procoagulant microparticles derived by the vesiculation of blood cells have been detected in patients with antiphospholipid syndrome (APS) frequently associated with antibodies against beta2GPI (anti-beta2GPI). We investigated the influence of beta2GPI and anti-beta2GPI on giant phospholipid vesicles (GPVs). GPVs composed of phosphatidylserine and phosphatidylcholine were formed in an aqueous medium and individually transferred to a compartment containing either beta2GPI, anti-beta2GPI, or beta2GPI along with anti-beta2GPI. Shape changes of a single GPV were observed by a phase contrast microscope. Most GPVs transferred to the solution containing only beta2GPI budded moderately. Upon the transfer of GPVs to the solution containing beta2GPI and anti-beta2GPI either from patient with APS or mouse monoclonal anti-beta2GPI Cof-22, the budding was much more pronounced, generating also daughter vesicles. No such effects were seen when GPV was transferred to the solution containing anti-beta2GPI without beta2GPI. Our results suggest a significant physiologic role of beta2GPI in the budding of phospholipid membranes, which may be explained by the insertion of the C-terminal loop of beta2GPI into membranes, thus increasing the surface of the outer layer of a phospholipid bilayer. Anti-beta2GPI, recognizing domains I to IV of beta2GPI, enhanced the budding and vesiculation of GPVs in the presence of beta2GPI. This might be a novel pathogenic mechanism of anti-beta2GPI, promoting in vivo the expression of proadhesive and procoagulant phospholipid surfaces in APS.

Suppressive effects of Sairei-to on mesangial proliferation in a rat model of glomerulonephritis

BACKGROUND

Sairei-to (TJ-114) is a Japanese herbal medicine of standardized quality, originating from traditional Chinese medicine. In the present in vivo study, we investigated the suppressive effects of TJ-114, Shosaiko-to (TJ-9), and Saiboku-to (TJ-96) on mesangioproliferative glomerulonephritis (MsPGN) in rats. We evaluated the efficacy of these drugs on proteinuria, mesangial cell proliferation, and superoxide dismutase (SOD) activity.

METHODS

MsPGN was induced in Wistar rats by intravenous injection of rabbit anti-rat thymocyte serum (ATS). TJ-114, TJ-9, or TJ-96 (500 mg/kg per day) was orally administered to the rats in drinking water from the day of ATS injection (day 0) to day 8, when rats were killed and kidney specimens were collected. The degree of mesangial cell proliferation was evaluated by immunostaining for proliferating cell nuclear antigen (PCNA) or macrophage antigen (ED-1). SOD activity in the homogenate of the renal cortex was also evaluated.

RESULTS

The amount of urinary albumin was significantly decreased only in the TJ-114-treated group compared with the disease control group ( P < 0.05). The number of PCNA- or ED-1-positive cells was significantly decreased in all the treatment groups ( P < 0.05, respectively, compared with the disease control group). SOD activity in the renal cortex homogenate was significantly augmented in all the treatment groups, most markedly in the TJ-96- and TJ-114-treated groups ( P < 0.01, respectively, compared with the disease control group).

CONCLUSIONS

These results suggest that TJ-114 suppresses the proliferation of mesangial cells through its antioxidative activity.

Enhancement of autoantibody pathogenicity by viral infections in mouse models of anemia and thrombocytopenia

Viral infections are involved in the pathogenesis of blood autoimmune diseases such as hemolytic anemia and thrombocytopenia. Although antigenic mimicry has been proposed as a major mechanism by which viruses could trigger the development of such diseases, it is not easy to understand how widely different viruses might induce these blood autoimmune diseases by this sole mechanism. In mice infected with lactate dehydrogenase-elevating virus (LDV), or mouse hepatitis virus, and treated with anti-erythrocyte or anti-platelet monoclonal autoantibodies at a dose insufficient to induce clinical disease by themselves, the infection sharply enhances the pathogenicity of autoantibodies, leading to severe anemia or thrombocytopenia. This effect is observed only with antibodies that induce disease through phagocytosis. Moreover, the phagocytic activity of macrophages from infected mice is increased and the enhancing effect of infection on autoantibody-mediated pathogenicity is strongly suppressed by treatment of mice with clodronate-containing liposomes. Finally, the disease induced by LDV after administration of autoantibodies is largely suppressed in animals deficient for gamma-interferon receptor. Together, these observations suggest that viruses may trigger autoantibody-mediated anemia or thrombocytopenia by activating macrophages through gamma-interferon production, a mechanism that may account for the pathogenic similarities of multiple infectious agents.

Pathogenic antiphospholipid antibody: an antigen-selected needle in a haystack

Antiphospholipid antibodies represent a heterogeneous group of autoantibodies directed against anionic phospholipids (PLs) usually linked to protein cofactors. Their presence during the antiphospholipid syndrome is associated with risks of thrombosis and fetal losses. Among 5 randomly selected monoclonal antiphospholipid antibodies, all originating from a single patient suffering from this autoimmune disease, only 1 induced fetal losses when passively injected into pregnant mice. Its antiphospholipid activity was dependent on annexin A5, and its variable regions contained mainly 3 replacement mutations. To clarify the role of these mutations in the pathogenicity of the antibody, they were in vitro reverted to the germ line configuration. The resulting “germ line” antibody reacted with multiple self-antigens and only partially lost its reactivity against PLs, but it was no more dependent on annexin A5 and, more importantly, was no more pathogenic. This study illustrates that the in vivo antigen-driven maturation process of natural autoreactive B cells can be responsible for pathogenicity. (Blood. 2004;104:1711-1715)

Effects of autoantibodies against β1-adrenoceptor in hepatitis virus myocarditis on action potential and L-type Ca2+ currents

AIM: To investigate the effects of autoantibodies against β₁-adrenoceptor in hepatitis virus myocarditis on action potential and L-type Ca²⁺ currents.

METHODS: Fifteen samples of autoantibodies against β₁-adrenoceptor positive sera of patients with hepatitis virus myocarditis were obtained and IgGs were purified by octanoic acid extraction. Binding of autoantibodies against β₁-adrenoceptor to guinea pig cardiac myocytes was examined by immunofluorescence. Using the patch clamp technique, the effects on the action potential and I_Ca-L of guinea pig cardiac myocytes caused by autoantibodies against β₁-adrenoceptor in the absence and presence of metoprolol were investigated. Cell toxicity was examined by observing cell morphology and permeability of cardiac myocytes to trypan blue.

RESULTS: The specific binding of autoantibodies against β₁-adrenoceptor to guinea pig cardiomyocytes was observed. Autoantibodies against β₁-adrenoceptor diluted at 1:80 prolonged APD₂₀, APD₅₀ and APD₉₀ by 39.2%, 29.1% and 15.2% respectively, and only by 7.2%, 5.3% and 4.1% correspondingly in the presence of 1 μmol/L metoprolol. Autoantibodies against β₁-adrenoceptor diluted at 1:80, 1:100 and 1:120 significantly increased the I_Ca-L peak current amplitude at 0 mV by 55.87 ± 4.39%, 46.33 ± 5.01% and 29.29 ± 4.97% in a concentration-dependent manner. In contrast, after blocking of β₁-adrenoceptors (1 μmol/L metoprolol), autoantibodies against β₁-adrenoceptor diluted at 1:80 induced a slight increase of I_Ca-L peak amplitude only by 6.81 ± 1.61%. A large number of cardiac myocytes exposed to high concentrations of autoantibodies against β₁-adrenoceptor (1:80 and 1:100) were turned into rounded cells highly permeable to trypan blue.

CONCLUSION: Autoantibodies against β₁-adrenoceptor may result in arrhythmias and/or impairment of myocardiums in HVM, which would be mediated by the enhancement of I_Ca-L.

Adenoviral infection decreases mortality from lipopolysaccharide-induced liver failure via induction of TNF-alpha tolerance

Effects of adenoviral infection on in vivo responses to LPS mediated by TNF-alpha were evaluated in a murine model. Adenovirus-infected mice showed decreased mortality from fulminant hepatitis induced by administration of LPS or staphylococcal enterotoxin B in the presence of D-galactosamine. Importantly, TNF-alpha resistance genes within adenoviral E3 region were not required, because E1,E3-deleted vectors showed similar effects. Adenovirus-infected mice exhibited higher TNF-alpha levels after LPS stimulation, no difference in TNFR1 expression, and similar mortality from Fas-induced fulminant hepatitis. Decreased production of IL-6 and KC in response to exogenous TNF-alpha, in addition to protection from TNF-alpha, suggested that adenoviral infection results in TNF-alpha tolerance.

Anti-apoptotic effects of CNTF gene transfer on photoreceptor degeneration in experimental antibody-induced retinopathy

Autoantibodies against recoverin are found in the sera of patients with cancer-associated retinopathy syndrome, a paraneoplastic disease associated with retinal degeneration. We have previously shown that anti-recoverin autoantibodies induced photoreceptor apoptotic cell death after injection into the vitreous of Lewis rats. Ciliary neurotrophic factor (CNTF) has been shown to promote the survival of a number of neuronal cell types, including photoreceptors. In this study, we examined whether an adeno-associated virus (AAV)-mediated delivery of gene encoding the human CNTF protected photoreceptor cells from anti-recoverin antibody-induced death. One month after subretinal injection of the AAV-CNTF gene into one eye and a control vector into the other eye, an anti-recoverin antibody was injected to induce retinal cell death in Lewis rats. Subretinal administration of the virus led to an efficient transduction of photoreceptors, as indicated by immunostaining of retinas with anti-CNTF. Histological examination of the corresponding retinas showed that photoreceptor cells were significantly protected from apoptotic death in the CNTF-treated eyes. CNTF treatment of the retinas resulted in a time-dependent activation of STAT 3. The present study shows that an AAV-mediated delivery of CNTF may protect photoreceptors from antibody-induced cell death through the activation of STAT3 and the suppression of caspase 3 activity, a key caspase leading to apoptosis. Thus, CNTF may be a useful treatment for human antibody-mediated retinal degeneration.

Autoantibodies to amyloid beta-peptide (Abeta) are increased in Alzheimer's disease patients and Abeta antibodies can enhance Abeta neurotoxicity: implications for disease pathogenesis and vaccine development

Studies of amyloid precursor protein transgenic mice suggest that immune responses to amyloid beta peptide (Abeta) may be instrumental in the removal of plaques from the brain, but the initial clinical trial of an Abeta vaccine in patients with Alzheimer s disease (AD) was halted as the result of serious neurological complications in some patients. We now provide evidence that AD patients exhibit an enhanced immune response to Abeta and that, contrary to expectations, Abeta antibodies enhance the neurotoxic activity of the peptide. Serum titers to Abeta were significantly elevated in AD patients and Abeta antibodies were found in association with amyloid plaques in their brains, but there was no evidence of cell-mediated immune responses to Abeta in the patients. Abeta antibodies were detected in the serum of old APP mutant transgenic mice with plaque-like Abeta deposits, but not in the serum of younger transgenic or nontransgenic mice. Serum from APP mutant mice potentiated the neurotoxicity of Abeta. Our data suggest that a humoral immune response to Abeta in AD patients may promote neuronal degeneration, a process with important implications for the future of vaccine-based therapies for AD.

Essential role of Fc gamma receptors in anti-type II collagen antibody-induced arthritis

Anti-type II collagen (anti-CII) Ab is a well-known autoantibody observed in patients with rheumatoid arthritis. Injection of anti-CII Ab and LPS induces arthritis in mice in which anti-CII Ab as well as inflammatory cytokines, IL-1beta and TNF-alpha, play critical roles. We investigated the involvement of IgG FcRs (FcgammaRs) in this arthritis model. BALB/c mice injected with the F(ab')(2) of anti-CII Ab showed no signs of arthritis. Arthritis development was not observed in FcRgamma(-/-) mice and was partially suppressed in FcgammaRIII(-/-) mice despite the binding of anti-CII Ab and C3 to cartilage surface. Surprisingly, BALB/c mice lacking FcgammaRIIB, which is known as an inhibitory FcgammaR, developed arthritis with no exacerbation in arthritis score compared with wild-type (WT) mice, and only slight exacerbation was observed in the histopathological analysis. In contrast, aged FcgammaRIIB(-/-) BALB/c mice developed arthritis without LPS injection, suggesting an augmented susceptibility to arthritis in aged FcgammaRIIB(-/-) mice. No significant difference was observed among BALB/c-WT, -FcRgamma(-/-), and -FcgammaRIIB(-/-) mice on cytokine production induced by anti-CII Ab and LPS injection. Severe arthritis developed in BALB/c-WT and -FcgammaRIIB(-/-) mice, but not in BALB/c-FcRgamma(-/-) mice, after the injection of anti-CII Ab and inflammatory cytokines. These results suggest that the reason behind the nondevelopment of arthritis in FcRgamma(-/-) BALB/c mice is not due to a disorder in transient cytokine production, but to an irregularity downstream of cytokine production.

An animal model of Tourette's syndrome

OBJECTIVE

An animal model was used to investigate an autoimmune etiology for some cases of Tourette's syndrome.

METHOD

Sera from 12 patients with Tourette's syndrome with high levels of antineural or antinuclear antibodies were infused bilaterally into the ventrolateral striatum of rats. Sera from 12 additional Tourette's syndrome patients and 12 normal subjects (both groups with low levels of autoantibodies) were infused for comparison. Rates of oral stereotypies were recorded by observers who were blind to the origin of the infused sera.

RESULTS

Oral stereotypies significantly increased in the rats infused with sera from the patients with high levels of autoantibodies.

CONCLUSIONS

The results are consistent with an autoimmune etiology in a subset of cases of Tourette's syndrome.

Blockade of TGF-beta signaling in T cells prevents the development of experimental glomerulonephritis

Anti-glomerular basement membrane (GBM) Ab-induced glomerulonephritis (GN) at late stage is thought to be mediated by T cells. However, signaling pathways of T cells that are involved in the development of anti-GBM Ab-induced GN are unclear. We have recently established transgenic mice expressing Smad7, an inhibitor of TGF-beta signaling, in mature T cells, where signaling by TGF-beta was blocked specifically in T cells. In this study, we showed that anti-GBM Ab-induced GN was suppressed in several measures in the transgenic mice including the severity of glomerular changes, proteinuria, renal function, and CD4 T cell infiltration into the glomeruli without down-regulation of CD62 ligand (CD62L) (L-selectin) expression on CD4 T cells. Furthermore, treatment with the soluble fusion protein of CD62L and IgG enhanced anti-GBM Ab-induced GN. These findings indicated that blockade of TGF-beta signaling in T cells prevented the development of anti-GBM Ab-induced GN. Because CD62L on T cells appears to be inhibitory for the development of anti-GBM Ab-induced GN, persistent expression of CD62L on CD4 T cells may explain, at least in part, the suppression of anti-GBM Ab-induced GN in the transgenic mice. Our findings suggest that the development of anti-GBM Ab-induced GN requires TGF-beta/Smad signaling in T cells.

GluR3 autoantibodies destroy neural cells in a complement-dependent manner modulated by complement regulatory proteins

GluR3 autoantibodies have been implicated in the development of Rasmussen's encephalitis, a rare neurodegenerative disease of humans characterized by epilepsy and degeneration of a single cerebral hemisphere. GluR3 autoantibodies are found in some Rasmussen's encephalitis patients, and GluR3 antibodies raised in rabbits destroy cultured cortical cells in a complement-dependent manner. In this study, the cellular targets of anti-GluR3 antisera-mediated cytotoxicity were examined in mixed primary neuronal-glial cultures of rat cortex. Unexpectedly, astrocytes were the principal target of the cytotoxic effects as assessed by immunohistochemistry and lactate dehydrogenase activity; neurons were destroyed to a lesser extent. Astrocyte vulnerability was rescued by transfection with complement regulatory proteins, and neuronal resistance was defeated by impairing complement regulatory protein function. Astrocyte death may occur in Rasmussen's encephalitis, and destruction of this cell type may play a critical role in the progression of this disorder. The present findings suggest complement regulatory protein expression may in part determine the nature and severity of Rasmussen's encephalitis and other complement-dependent nervous system diseases and thus underscore the need for a systematic investigation of the expression of all known complement regulatory proteins in healthy and diseased nervous system tissues.

Anti-human cardiac myosin autoantibodies in Kawasaki syndrome

Kawasaki syndrome (KS) is the major cause of acquired heart disease in children. Although acute myocarditis is observed in most patients with KS, its pathogenesis is unknown. Because antimyosin autoantibodies are present in autoimmune myocarditis and rheumatic carditis, the purpose of the current study was to determine whether anticardiac myosin Abs might be present during the acute stage of KS. Sera from KS patients as well as age-matched febrile controls and normal adults were compared for reactivity with human cardiac myosin in ELISAs and Western blot assays. A total of 5 of 13 KS sera, as compared with 5 of 8 acute rheumatic fever sera, contained Ab titers to human cardiac myosin that were significantly higher than those found in control sera. Both cardiac and skeletal myosins were recognized in the ELISA by KS sera, although stronger reactivity was observed to human cardiac myosin. Only IgM antimyosin Abs from KS sera were significantly elevated relative to control sera. KS sera containing antimyosin Abs recognized synthetic peptides from the light meromyosin region of the human cardiac myosin molecule and had a different pattern of reactivity than acute rheumatic fever sera, further supporting the association of antimyosin Ab with KS. These Abs may contribute to the pathogenesis of acute myocarditis found in patients with KS.

Early anti-nucleosome autoantibodies from a single MRL+/+ mouse: fine specificity, V gene structure and pathogenicity

In systemic lupus erythematosus, the nucleosome assumes a central role in the autoimmune response to self antigens. To gain insight into the etiology and pathogenesis of anti-nucleosome antibodies (Ab), we analyzed a panel of six IgG-secreting hybridomas derived from a single young MRL +/+ mouse at the onset of the autoimmune response. All monoclonal antibodies (mAb) bound exclusively the native nucleosome, and represented five different clonotypes that recognized diverse nucleosomal epitopes, typical of a polyclonal response. The VH-complementarity-determining region (CDR)3 regions exhibited unique stretches of charged amino acids with different polarity that may be important for the interaction with the nucleosome. These early anti-nucleosome mAb displayed striking structural differences with not only anti-DNA, but also with anti-nucleosome Ab, that appear later in disease. Two of the mAb deposited in kidney glomeruli after in vivo administration to RAG-1-deficient mice, suggesting that diverse B cell clones, possibly selected by the nucleosome itself, may play a role in the initiation of kidney damage.

Antibodies against desmoglein 3 (pemphigus vulgaris antigen) are present in sera from patients with paraneoplastic pemphigus and cause acantholysis in vivo in neonatal mice

Paraneoplastic pemphigus (PNP) is an autoimmune blistering disease that occurs in association with underlying neoplasms. Patients with PNP develop characteristic IgG autoantibodies directed against multiple antigens, most of which have been identified as cytoplasmic proteins of the plakin family (desmoplakin I, II, BPAG1, envoplakin, and periplakin). This study identified cell surface target antigens of PNP. We focused on desmoglein (Dsg) 3 and Dsg1, the autoantigens of pemphigus vulgaris and pemphigus foliaceus. ELISA using baculovirus-expressed recombinant Dsgs (rDsg3, rDsg1) has revealed that 25 out of 25 PNP sera tested were positive against Dsg3 and 16 of 25 were positive against Dsg1. All of 12 PNP sera tested immunoprecipitated Dsg3. Removal of anti-Dsg3 autoantibodies by immunoadsorption was sufficient to eliminate the ability of PNP sera to induce cutaneous blisters in neonatal mice in vivo. Furthermore, anti-Dsg3-specific antibodies that were affinity purified from PNP sera were proven to be pathogenic and caused blisters in neonatal mice. These findings indicate that Dsg3 and Dsg1 are the cell surface target antigens in PNP and that IgG autoantibodies against Dsg3 in PNP sera play a pathogenic role in inducing loss of cell adhesion of keratinocytes and causing blister formation.

Autoantibodies to ribosomal P proteins penetrate into live hepatocytes and cause cellular dysfunction in culture

Abs to ribosomal P protein have been shown to bind a membrane form of the P0 38-kDa ribosomal phosphoprotein. This study shows that after affinity-purified Abs to ribosomal P proteins bind living HepG2 cells, they then penetrate these live cells and cause cellular dysfunction. Binding and penetration of anti-P Abs is the property of F(ab')2 fragments as well as whole IgG molecules showing that neither binding nor penetration depends on Fc fragments or their cognate receptors. Confocal microscopy shows that internalized Ab concentrates in perinuclear vesicles (presumably lysosomes), but substantial quantities of Ab are also found in the cytosol. This intracellular Ab adversely affects the synthesis of apolipoprotein B resulting in a threefold increase in cellular cholesterol with lipid droplet accumulation as seen in some chronic liver diseases. It also has a profound inhibitory effect on global protein synthesis as measured by [35S]methionine incorporation. These studies therefore describe a model of cellular injury effected by specific Ab to ribosomal "P" protein that may underlie certain forms of autoimmune hepatic diseases.

Autoantibodies in conventional toxicity testing

A number of drugs and chemicals can induce autoimmune disorders. The use of autoantibody assays in toxicology has been evaluated as a tool to predict and explain autoimmune reactions. Autoantibodies are divided between organ-specific and ubiquitous autoantibodies and several mechanisms have been proposed for their pathogenesis. Assay methods depend on the autoantibody investigated and the specificity of the assay required. There is only a partial correlation between the presence of autoantibodies in humans or animals and the risk of developing an autoimmune disease. Responses in animals vary according to genetic influence and extrapolation to humans is difficult. Therefore, autoantibody assays were not considered absolutely predictive of the potential of a new drug to trigger autoimmune diseases. However assays such as the Coombs test for hemolytic anemia or anti-thyroid antibody assay for thyroiditis, can be useful for explaining the possible mechanisms of autoimmune reactions which occur during toxicology studies.

Anti-cytokine autoantibodies: epiphenomenon or critical modulators of cytokine action

Low amounts of high-affinity autoantibodies to various cytokines have been detected in sera from healthy donors. Their levels, although highly variable, are increased in the circulation of patients subjected to cytokine therapy or suffering from a variety of immunoinflammatory diseases. It has been suggested that these autoantibodies play a regulatory role in the intensity and duration of an immune response. The antibodies may prevent the binding of a cytokine to its specific cell surface receptor thereby neutralizing its biological activity in vivo. They may also act as carrier proteins preventing the rapid elimination of a cytokine from the circulation and thus increase its bioactivity. Additionally or alternatively, autoantibodies may modulate cytokine-induced intracellular signal transduction pathways or trigger complement-mediated cytotoxicity towards cells carrying membrane-bound cytokines. The autoantibodies may exert their regulatory role in compliance with the other factors that control cytokine activity, including soluble cytokine receptors, cell surface decoy receptors, and receptor antagonists. Although not favored by many investigators, a less sophisticated role for naturally occurring anti-cytokine autoantibodies should be considered as well. Recent evidence has shown that autoantibodies are generated at a high frequency as part of a response to foreign antigens. These antibodies are produced by B cells arising from the process of somatic mutation. Thus anti-cytokine autoantibodies may be the result of a "leaky" B cell response triggered by immunoinflammatory processes. High-titered autoantibodies induced by cytokine therapy are of clinical concern since their occurrence is often associated with the loss of response to treatment. Moreover, they may also neutralize endogenously produced cytokines with possible pathological consequences. In this paper we have reviewed the available information on the biological and clinical significance of both naturally occurring and therapeutically induced anti-cytokine autoantibodies in animals and man with the emphasis on antibodies directed to interferons.

Antibodies to endothelial cells in Kawasaki disease lyse endothelial cells without cytokine pretreatment

Kawasaki disease (KD) is characterized by diffuse vasculitis and marked immune activation. To confirm the presence of antiendothelial cell antibodies (AECA) and cytotoxicity of AECA, we investigated the presence of AECA using ELISA and cytotoxicity of AECA in KD. Sera from patients with acute KD were assessed for binding to human umbilical vein endothelial cells (HUVEC) using a cell-based ELISA, and for cytotoxicity against HUVEC as indicated by the conversion of a tetrazolium salt (MTT) into a coloured product. IgM AECA were detected in 8/19 KD sera, IgG AECA were detected in 5/19 KD sera. Significant differences in both AECA titres existed between patients and febrile and afebrile controls. Six out of 19 patients showed complement-dependent cytotoxicity against HUVEC. Cytotoxicity was significantly enhanced by pretreating HUVEC with tumour necrosis factor (TNF), and reduced by incubation with gammaglobulin. Serum titres of IgM AECA in the KD patients were positively correlated with cytotoxicity. Findings suggest that IgM AECA mediates complement-dependent cytotoxicity against endothelial cells in patients with KD, and gammaglobulin may reduce complement-dependent cytotoxicity of AECA against endothelial cells.

Arteritis in a novel congenic strain of mice derived from MRL/Lpr lupus mice: genetic dissociation from glomerulonephritis and limited autoantibody production

An MRL/Mp strain of mice bearing the Fas deletion mutant gene, lpr (MRL/lpr), spontaneously develop systemic vasculitis and glomerulone phritis in the same individual, and both have been thought to be associated with an increase in circulating immune complexes and autoantibodies. However, the genetic basis of these diseases is poorly understood. A novel recombinant congenic mouse strain, McH5-lpr/lpr, which was established by rearrangement of the genetic background of MRL/lpr mice by hybridization with C3H/HeJ-lpr/lpr mice, developed severe granulomatous polyarteritis, as did the MRL/lpr strain, but not glomerulonephritis. Serum levels of anti-DNA and anti-myeloperoxidase antibodies in these mice were significantly reduced, as compared with MRL/lpr mice, although rheumatoid factors were not. These results indicate that each of these two diseases, arteritis and glomerulonephritis, is under the control of different background gene(s), suggesting a different pathological basis of these diseases, and that anti-DNA and anti-myeloperoxidase autoantibodies appear to have a limited pathogenic role in granulomatous arteritis in the mouse strain described.

Autoantibodies to myeloperoxidase aggravate mild anti-glomerular-basement-membrane-mediated glomerular injury in the rat

Autoantibodies to myeloperoxidase (MPO) are present in sera from patients with various forms of vasculitis-associated glomerulonephritis. Evidence for a pathogenic role of anti-MPO antibodies has been provided mainly by in vitro studies. We studied the pathogenic role of autoantibodies to MPO in a rat model of mild immune-mediated glomerular injury. Brown Norway rats were immunized with human MPO in complete Freund's adjuvant or with complete Freund's adjuvant alone. At 2 weeks after immunization, rats had developed antibodies to human and rat MPO as detected by indirect immunofluorescence, enzyme-linked immunosorbent assay, and immunoprecipitation. At this time point, rats were intravenously injected with a subnephritogenic dose of 150 micrograms of rabbit anti-rat GBM. Rats were sacrificed at 4 hours, 24 hours, 4 days, and 10 days after antibody administration. Control immunized rats developed mild glomerulonephritis characterized by slight proteinuria at day 10 (14.8 +/- 8.1 mg/24 hours) and moderate intraglomerular accumulation of ED1+ macrophages. Crescent formation, tuft necrosis, and tubular atrophy were not observed in those rats. In contrast, rats immunized with MPO developed severe glomerulonephritis characterized by the early occurrence of severe hematuria, marked proteinuria at day 10 (76.2 +/- 18.2 mg/24 hours), and massive glomerular deposition of fibrin. Complement and rat IgG were present in insudative lesions, but no linear pattern along the glomerular capillary wall was observed. By light microscopy, severe glomerular lesions were found at day 10 consisting of crescent formation and fibrinoid necrosis of capillary loops. In the interstitium, tubular necrosis and atrophy and marked interstitial mononuclear infiltration were found in conclusion, autoantibodies to MPO severely aggravate subclinical anti-GBM disease demonstrating their in vivo pathogenic potential.

Participation of glomerular endothelial cells in the capillary repair of glomerulonephritis

In many glomerular diseases severe injury to the mesangium may occur, leading to matrix dissolution and damage to the glomerular capillaries. Although the destruction of glomerular architecture may lead to permanent injury, in some cases spontaneous recovery occurs. The mechanisms that mediate this recovery are unknown. In this study we provide evidence for glomerular capillary repair (angiogenesis) in the adult injured glomerulus. Injection of anti-Thy 1 antibody into rats results in severe mesangiolysis with capillary ballooning, microaneurysm formation, and loss of endothelial cells in addition to mesangial cells. Although mesangial proliferation is a major response to injury, proliferation of endothelial cells also can be documented from days 2 to 14 in association with repair of the capillaries. The endothelial cell proliferation peaks on days 2 and 7, when it is seven- to ninefold greater than normal. Many of the endothelial cells display morphological features of angiogenesis. The initial wave of endothelial cell proliferation can be reduced by 40% with neutralizing anti-basic fibroblast growth factor antibodies (P < 0.001). The later glomerular endothelial cell proliferation is associated with upregulated expression of vascular permeability factor/endothelial cell growth factor (VPF/VEGF) and an increase of flk, a VPF/VEGF receptor. Although PDGF is expressed in this model, anti-PDGF antibody treatment did not affect the endothelial cell proliferative response. In summary, glomerular endothelial cells have an active role in the glomerular response to injury. Glomeruli are capable of healing microaneurysms, and the mechanism involves basic fibroblast growth factor- and VPF/VEGF-mediated endothelial proliferative responses.

Autoantibodies against beta-crystallins induce lens epithelial cell damage and cataract formation in mice

One-year-old B6C3/f mice, injected with beta-crystallins emulsified with CFA, developed lens epithelial cell damage. Both serum transfer and mAb transfer studies clearly established that the autoimmune insult is induced by humoral immunity. Older mice were more susceptible to autoimmune insult than younger animals. Lens epithelial cell damage invariably proceeded to cortical and posterior subcapsular cataract formation. This mouse model of experimental autoimmune cataract formation will facilitate the exploration of the relation between immune phenomena and human age-related cataract.

Methionine overcomes neural tube defects in rat embryos cultured on sera from laminin-immunized monkeys

Sera from laminin-immunized monkeys were previously found to cause neural tube defects in cultures of whole rat embryos by unknown mechanisms. In the present study, adding L-methionine to either the culture media or to the diets of the monkeys overcame the toxicity of the serum from one of these monkeys (LAM3) but not the other (LAM4). The antilaminin antibody levels and avidities for isolated murine laminin of sera from the two monkeys were comparable. However, when yolk sac homogenates were tested on ELISA, antibodies from LAM4 had greater binding than LAM3, which was further supported by immunoelectron microscopy. These differences in antibody binding were explained by the findings that antibodies from LAM4 recognized more epitopes than LAM3 and that LAM4 recognized specific epitopes not recognized by LAM3. These antibodies caused reductions in the number of microvilli on the cells and the cell sizes of the yolk sac endoderm. In addition, uptake of [14C]methionine, [14C]sucrose and [14C]valine by yolk sacs from embryos cultured on serum from LAM4 was less than that for LAM3. We suggest that the neural tube defects caused by the antilaminin antibodies were a result of reduced nutrient flow caused by the reduction in the number of microvilli on the cells of the yolk sac endoderm.

Correlation of peptide specificity and IgG subclass with pathogenic and nonpathogenic autoantibodies in pemphigus vulgaris: a model for autoimmunity

Pemphigus vulgaris (PV) is a rare, potentially fatal, autoimmune disease that affects the skin and mucous membranes. The PV antigen (PVA) has been characterized as desmoglein 3. PV patients carry HLA-DR4- or HLA-DR6-bearing extended haplotypes. We recently demonstrated that patients with active disease have high titers of PV autoantibodies of the IgG1 and IgG4 subclasses. Patients in remission, healthy unaffected relatives, and some MHC-matched normal individuals have low levels of PV autoantibodies, which are IgG1 only. Furthermore, intraperitoneal injection of IgG from patients with active disease caused clinical disease in mice, but IgG from patients in remission, healthy relatives, or MHC-matched normal individuals did not. We prepared 12 peptides of 30 amino acids each (peptides Bos 1-12) spanning the extracellular domain of PVA. Patients with active disease recognize peptides Bos 1 and Bos 6 with high titers of IgG1 and IgG4 autoantibodies. Patients in remission have IgG1 autoantibodies to peptide Bos 1 only, in statistically significantly lower titers (P < 0.01). They no longer have IgG4 subclass autoantibodies to peptide Bos 6. Healthy relatives and normal unrelated individuals have low levels of only IgG1 autoantibodies that recognize only Bos 1. In vitro studies indicate that Bos 6-specific IgG and, to a lesser extent, Bos 1-specific IgG can cause acantholysis. Our data suggest that Bos 6-specific IgG4 is probably the main acantholytic autoantibody, while Bos 1-specific IgG4 may act as a facilitator or enhancer of the process. In this study we illustrate some of the paradigms that demonstrate the interactions between the MHC, subclass of autoantibodies, and peptide specificities of the autoantibodies in the autoimmune process. Thus, PV provides an important model to study the pathogenesis of autoimmunity.

Anti-B-series ganglioside-recognizing autoantibodies in an acute sensory neuropathy patient cause cell death of rat dorsal root ganglion neurons

To examine the cytotoxicity of a patient's serum with an acute relapsing sensory neuropathy syndrome, dorsal root ganglion neurons from young adult rats were cultured in the presence of the patient's serum which had an extremely higher-titer monoclonal IgM antibody recognizing B-series gangliosides, GD2, GD1b, GT1b and GQ1b. By the addition of the inactivated patient's serum, the relatively larger cells died after undergoing of metamorphosis during several hours of culture, whilst the smaller cells survived. The IgM fraction isolated from the patient's serum showed similar cytotoxicity towards the neurons as the inactivated whole serum. No cytotoxicity was observed with the IgM fraction-containing medium after it had been absorbed with ganglioside GD1b. The results suggested that the anti-B-series ganglioside-directed antibody is the causal agent for the human neurologic disease.

Role of laminin autoantibodies on the embryo toxicity of sera from mercuric chloride treated brown Norway rats

In previous studies, antilaminin antibodies were found to be toxic to cultured rat embryos. In order to extend these studies, Brown Norway rats were treated with mercuric chloride, which led to the production of laminin autoantibodies. Sera samples from brown Norway rats treated with mercuric chloride were found to be teratogenic as well as lethal to cultured rat embryos. This embryotoxicity was not associated with sera mercury levels, but was related to the levels of antilaminin antibodies in sera. Affinity purified laminin antibodies from these mercuric chloride treated Brown Norway rats, when added to control sera, were found to be teratogenic but not lethal. These antibodies were found to bind to the laminin sequences IKVAV (A chain) and YIGSR (B1 chain), but not RGD (A chain) or YD (B1 chain). These observations suggested the possibility that an environmental pollutant such as mercury could cause the formation of embryotoxic autoantibodies that could persist in the body as embryotoxic factors for extended periods of time.

Autoantibodies against the amino-terminal cadherin-like binding domain of pemphigus vulgaris antigen are pathogenic

Complementary DNA cloning of the 130-kD pemphigus vulgaris (PV) autoantigen (PVA) has indicated that it is a member of the cadherin family of Ca(2+)-dependent cell adhesion molecules. By homology with typical cadherins, PVA has five extracellular domains (EC1 through EC5). To localize immunogenic domains and to determine whether antibodies against them might be pathogenic, we produced beta-galactosidase fusion proteins with cDNA encoding different portions of the extracellular domains of PVA (EC1-2, EC3-5, and each individual domain). Immunoblot analysis of these fusion proteins with 23 PV patients' sera demonstrated that major immunogenic regions of PVA are located on the EC1, EC2, and EC4 domains. IgG was affinity-purified from PV sera on fusion proteins representing the amino (EC1-2) and carboxy (EC3-5) terminus of the extracellular PVA, and injected into neonatal mice. PV IgG affinity-purified on the EC1-2 fusion protein caused suprabasilar acantholysis, the typical histological finding of PV, but IgG affinity-purified on the EC3-5 fusion protein or beta-galactosidase alone did not. These results indicate that at least one pathogenic epitope, which is sufficient to cause suprabasilar acantholysis in neonatal mice, is located on the amino-terminal region of PVA, an area thought to be important in cadherin homophilic adhesion.

Effect of intraventricular injection of an anti-Purkinje cell antibody (anti-Yo) in a guinea pig model

Female guinea pigs had intraventricular injections of either IgG from a patient with paraneoplastic cerebellar degeneration (PCD) and anti-Purkinje cell antibodies (anti-Yo IgG) or control IgG. In animals that received a single injection of control or anti-Yo IgG and were killed at different time intervals, IgG immunoreactivity was present in the cytoplasm of Purkinje cells at 2 h and persisted at 24 h. In guinea pigs injected for 15 days with control or anti-Yo IgG and sacrificed 24 h after the last injection, IgG was detected into the Purkinje cells in both groups, whereas animals killed 7 and 30 days after the last injection had no staining for IgG in the Purkinje cells. Clinical or pathologic evidence of cerebellar involvement was not seen in any of the animals. This study suggests that anti-Yo antibody alone may not be the cause of the Purkinje cell loss in PCD.

Histological and functional changes in the thyroid glands of mice implanted with hybridomas secreting monoclonal autoantibody against mouse thyroglobulin

Mouse hybridoma cells secreting monoclonal antibody (mAb) against mouse thyroglobulin were established. The implantation of the hybridomas succeeded to induce high titers of circulating mAb against thyroglobulin in sera of mice. By using the implantation of the hybridomas in mice, the effect of autoantibody on the thyroid glands was studied histologically and functionally. In these mice the thyroid follicles were significantly swollen and warped, whereas there was no infiltration of inflammatory cells. The 125I-uptake in their thyroid glands was markedly decreased. There were no functional changes in control mice implanted with non-secreting P3U1 partner cells. Therefore, it was suggested that high titers of anti-thyroglobulin autoantibody could definitely cause the histological and functional damages in the thyroid glands.

Local tissue injury induced by glucose oxidase conjugated with anti-collagen antibody

The conjugation of glucose oxidase with anti-collagen antibody using periodate oxidation of the enzyme carbohydrate moiety is described. After conjugation, the antibody retained its antigen-binding capacity and the enzyme retained hydrogen peroxide-generating activity. Intradermal administration of the immune conjugate into rats induced local tissue injury at doses 10-100 micrograms. Pronounced damage (local hyperemia and edema) occurred 24 h after injection and necrosis developed 1 week later. The enzyme was tightly bound to the fibrillar components of the extracellular matrix and retained its activity in vivo for a prolonged period of time. In contrast, non-immune IgG-conjugated glucose oxidase was removed rapidly from the site of injection and did not induce tissue damage. Pure native anti-collagen antibody was retained at the site of injection for 8 days, but caused no tissue injury. These results suggest that active glucose oxidase conjugated with antibodies to tissue antigen can be accumulated and retained in the tissues. At the site of accumulation local 'proinflammatory' damage develops even in the absence of the halide-peroxidase system. Similar conjugates could be potential agents for local modulation of inflammation.

Isoproterenol induced myocardial lesions in the immunized and non-immunized rat. II. Histopathological lesions after specific immunization

Rats killed 24 hours after a single injection of 30–100 mg/kg Isoproterenol (N-iso-propyl noradrenaline), show focal myocardial necrosis. Animals previously immunized against homologous (rat) heart homogenate showed a marked increase in severity and extent of the lesions. Immunization against rabbit heart caused a lesser degree of enhancement; rat kidney, rabbit serum and kidney and saline—adjuvant emulsion as antigens, gave results similar to the controls.

There was no correlation between the level of circulating anti-heart antibodies, as measured by passive haemagglutination, and the severity of the myocardial necrosis. Within each treatment group, however, animals with higher titres tended to show greater myocardial damage.

It is suggested that circulating anti-heart antibodies, normally non-toxic in vivo, become cytopathogenic after the myofibre cell barrier is broken down by Isoproterenol.