Increased Autoantibody Titers Research Articles

RELAPSING POLYCHONDRITIS IN RHEUMATOLOGY PRACTICE

The paper provides a clinical description of relapsing polychondritis, a rare systemic immunoinflammatory disease that was characterized by fever episodes, cartilage damage, and reactive arthritis. Diagnostic searching could rule out an infectious disease (by determining a wide variety of potential pathogens), as well as a septic condition due to a pronounced leukemoid reaction of the myeloid type, and the presence of toxigenic neutrophil granulation in peripheral blood and bone marrow. All available clinical, functional, and radiological studies were used to make a differential diagnosis with paraneoplastic syndrome due to blood disease, primarily with myeloma. The data obtained could interpret the changes only as reactive. No increased autoantibody titers were identified. Clinical symptoms and the good effect of prednisolone therapy allowed a diagnosis of relapsing polychondritis, a rare disease that belongs to the group of immunoinflammatory diseases according to the current ideas. It is suggested that autoinflammation plays a role in its pathogenesis.

An upregulation of TLR7 in renal dendritic cells is associated with glomerulonephritis across multiple B6. Sle1-associated strains.

Abstract Toll-like receptors (TLRs) 7 and 9 are important innate signalling molecules with opposing roles in the development and progression of Systemic Lupus Erythematosus (SLE). While multiple studies support a dependency on TLR7 for disease development, genetic ablation of TLR9 results in severe disease with glomerulonephritis (GN) by a largely unknown mechanism. In the present study we show that the autoimmune phenotypes exhibited by TLR9-deficient Sle1 mice (Sle1TLR9−/−) mice are akin to those shown by the Sle1Tg7 strain, a model with a 2-fold increase in TLR7 expression. These include increased autoantibody titers, systemic immune activation and glomerulonephritis (GN). Kidney disease in Sle1TLR9−/− mice is associated with an increase in renal CD11b+CD11c+MHC+F480− dendritic cells (DC). These cDCs have higher levels of TLR7 protein with a corresponding increased ability to stimulate T cell proliferation following R848 exposure. Our analyses of TLR7 using flow cytometry in the Sle1Tg7 and Sle123 murine lupus models indicated similar increases in protein expression within cDCs, suggesting their importance across multiple model systems. Genetic ablation of TLR9 in Sle1 mice also resulted in increased TLR7-reactive RNA/anti-RNA-associated autoantibodies, indicating that TLR9 is required for B cell tolerance to RNA-associated antigens. In summary, the increase in TLR7-reactive immune complexes (IC) and the concomitant enhanced expression of their receptor, promotes Inflammation and Disease in Sle1TLR9−/− mice.

Stat1 Regulates Lupus-like Chronic Graft-versus-Host Disease Severity via Interactions with Stat3.

Systemic lupus erythematosus (SLE) is a complex multisystem autoimmune disease, characterized by a spectrum of autoantibodies that target multiple cellular components. Glomerulonephritis is a major cause of morbidity in patients with SLE. Little is known about the pathogenesis of SLE renal damage and compromised renal function. Activation of both Stat1 and Stat3 has been reported in lupus and lupus nephritis. The reciprocal activation of these two transcription factors may have a major impact on renal inflammation. To study the role of Stat1 in a lupus model, we induced lupus-like chronic graft-versus-host disease (cGVHD) in Stat1-knockout (KO) and wild-type (WT) mice by i.p. injection of class II-disparate bm12 splenocytes. WT recipients of these alloreactive cells developed anti-dsDNA autoantibodies starting at week 2 as expected, with a decline after week 4. In contrast, Stat1-KO hosts exhibited a prolonged and significant increase of anti-dsDNA autoantibody responses compared with WT mice (week 4 to week 8). Increased autoantibody titers were accompanied by increased proteinuria and mortality in the cGVHD host mice lacking Stat1. Further analysis revealed expression and activation of Stat3 in the glomeruli of Stat1-KO host mice but not WT mice with cGVHD. Glomerular Stat3 activity in the Stat1-KO mice was associated with increased IL-6 and IFN-γ secretion and macrophage infiltration. Interactions between Stat1 and Stat3 thus appear to be crucial in determining the severity of lupus-like disease in the cGVHD model.

Regulation of Lupus Nephritis by Stat3

Systemic lupus erythematosus (SLE) is an autoimmune disorder often accompanied by nephritis, causing considerable morbidity and mortality [1,2]. Increased expression of type I Interferon (IFN) and interferon-inducible genes are frequently observed in cells from SLE patients and is associated with disease activity [3]. Activation of the interferon signaling molecules, Stat1 and Stat3, has also been reported in SLE [4,5]. Their activation levels correlated with many forms of glomerulonephritis. The reciprocal activation of these two transcription factors may have a major impact on renal inflammation. To study the role of Stat1 in a lupus model, we induced SLE-like chronic graft-versus-host disease (cGVHD) in Stat1-KO and in WT mice by intraperitoneal injection of class II-disparate bm12 splenocytes [6]. WT recipients of these alloreactive cells developed anti-dsDNA autoantibodies starting at week 2 as expected, with a decline after week 4. In contrast, Stat1-KO hosts exhibited a prolonged and significant increase of anti-dsDNA autoantibody responses compared to WT mice (week 4 to week 8). Increased autoantibody titers were accompanied by increased proteinuria and mortality in the cGVHD host mice lacking Stat1. Enhanced expression and activation of Stat3 were observed in the glomeruli of Stat1-KO host mice but not WT mice with cGVHD. Interactions between Stat1 and Stat3 thus appear to be crucial in determining the severity of lupus-like disease in the cGVHD model [6].

A suppressive role of STAT1 in lupus-like chronic graft versus host disease (IRM7P.479)

Abstract Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease driven by genetic and environmental factors with unknown etiopathogenesis. The bm12→B6 chronic graft-versus-host disease (cGVHD) is a well-studied inducible mouse model of SLE. STAT1 is dynamically regulated during the course of immune and inflammatory responses. However, little is known about the role of STAT1 in autoimmune diseases. We induced cGVHD in B6.STAT1-KO and B6.WT mice by intraperitoneally injection of 1×108 splenocytes from bm12 mice. Mice were followed for autoimmune manifestations, such as mortality, skin rash, and renal involvement. Upon injection, WT mice developed anti-dsDNA autoantibodies starting at week 2 (as expected), with decline noted after week 4. In contrast, STAT1-deficient mice exhibited a prolonged and significant increase of anti-dsDNA autoantibody responses compared to WT mice (week 4 to week 8). Severe splenomegaly also developed in cGVHD STAT1-KO mice. Increased autoantibody titers were accompanied by increased proteinuria in mice lacking STAT1 due to immune complex deposition. Three months after injection, 40% of the STAT1-KO mice with cGVH disease were dead. Anti-dsDNA isotypes in cGVH diseased STAT1-KO mice were enhanced (IgG1 responses), but IgG3 responses were absent. STAT1 seems to suppress systemic autoimmunity by altering autoantibody isotype switching. Results from these studies may provide insights into the pathogenesis of STAT1 in SLE.

Absence of CD59 Exacerbates Systemic Autoimmunity in MRL/lpr Mice

CD59 is a GPI-anchored membrane regulator of complement expressed on blood cells as well as peripheral tissues. It protects host cells from complement injury by inhibiting formation of the membrane attack complex. Recent studies in mice have suggested also a role of CD59 in T cell immune response that was mechanistically independent of complement. In the present study, we investigated the function of CD59 in the MRL/lpr model of murine lupus. We backcrossed the Cd59a knockout (Cd59a(-/-)) mouse onto the MRL/lpr background and compared Cd59a(+/+)-MRL/lpr and Cd59a(-/-)-MRL/lpr littermates for the development of systemic autoimmunity. We found that CD59a deficiency significantly exacerbated the skin disease and lymphoproliferation characteristic of MRL/lpr mice. It also increased autoantibody titers and caused a higher level of proteinuria in male MRL/lpr mice. Bone marrow transfer experiments indicated that CD59a expression on both bone marrow-derived cells and peripheral tissues played a role in lymphoproliferation, whereas the skin disease phenotype is determined mainly by local CD59a expression. Importantly, C3 gene deletion or C5 neutralization with a blocking mAb in Cd59a(-/-)-MRL/lpr mice did not rescue the proautoimmune phenotype associated with CD59a deficiency. These results together suggest that CD59a inhibits systemic autoimmunity in MRL/lpr mice through a complement-independent mechanism.

BCR/TLR7 coligation uniquely drives plasma cell differentiation of autoreactive B cells (171.34)

Abstract Endosomal Toll-like receptors (TLRs) play an important role in the manifestation of systemic autoimmune diseases such as SLE. In vitro, DNA-/RNA-associated autoantigens have been reported to activate B cells, pDCs, and other APCs, through TLR9/TLR7-dependent pathways. However, in vivo, TLR9 appears to negatively regulate TLR7-dependent responses. Hence, TLR9-/- autoimmune prone mice develop more severe disease and increased autoantibody titers against RNA associated proteins, while TLR7-/- and TLR7/9-/- autoimmune-prone mice develop less severe disease. AM14 BCR side-directed transgenic B cells recognize IgG2a-bound immune complexes (ICs) and initially proliferate in response to both DNA and RNA autoantigens. However, the TLR9-dependent DNA responses eventually promote a form of programmed cell death that can only be rescued by B cell survival factors such as BLyS. By contrast, the TLR7-dependent RNA responses promote differentiation to the plasma cell lineage. The RNA-driven phenotype is characterized by increased levels of plasma cell associated proteins such as IRF-4 and CD138 and antibody secretion. Even in the presence of BLyS, DNA containing ICs did not promote plasma cell development. Our results identify B cell intrinsic mechanisms whereby TLR9 activation restrains B cell responses and TLR7 activation induces a unique signal for plasma cell development.

Relationship of IgG and IgM autoantibodies and immune complexes to oxidized LDL with markers of oxidation and inflammation and cardiovascular events: results from the EPIC-Norfolk Study

Levels of IgG and IgM autoantibodies (AA) to malondialdehyde (MDA)-LDL and apoB-immune complexes (ICs) were measured in 748 cases and 1,723 controls in the EPIC-Norfolk cohort and their association to coronary artery disease (CAD) events determined. We evaluated whether AA and IC modify CAD risk associated with secretory phospholipase A(2) (sPLA(2)) type IIA mass and activity, lipoprotein-associated PLA(2) activity, lipoprotein (a) [Lp(a)], oxidized phospholipids on apoB-100 (OxPL/apoB), myeloperoxidase, and high sensitivity C-reactive protein. IgG ICs were higher in cases versus controls (P = 0.02). Elevated levels of IgM AA and IC were inversely associated with Framingham Risk Score and number of metabolic syndrome criteria (p range 0.02-0.001). In regression analyses adjusted for age, smoking, diabetes, LDL-cholesterol, HDL-cholesterol, and systolic blood pressure, the highest tertiles of IgG and IgM AA and IC were not associated with higher risk of CAD events compared with the lowest tertiles. However, elevated levels of IgM IC reduced the risk of Lp(a) (P = 0.006) and elevated IgG MDA-LDL potentiated the risk of sPLA(2) mass (P = 0.018). This epidemiological cohort of initially healthy subjects shows that IgG and IgM AA and IC are not independent predictors of CAD events but may modify CAD risk associated with elevated levels of oxidative biomarkers.

Relationship of IgG and IgM autoantibodies to oxidized low density lipoprotein with coronary artery disease and cardiovascular events

The relationship between autoantibodies to oxidized low density lipoprotein (OxLDL) and coronary artery disease (CAD) remains controversial. IgM and IgG OxLDL autoantibodies to malondialdehyde (MDA)-modified LDL, copper oxidized low density lipoprotein (CuOxLDL), and oxidized cholesterol linoleate (OxCL), as well as apolipoprotein B-100 immune complexes (apoB-ICs), were measured in 504 patients undergoing clinically indicated coronary angiography. Patients were followed for cardiovascular events for a median of 4 years. In univariate analysis, IgM OxLDL autoantibodies and IgM apoB-ICs were inversely associated with the presence of angiographically determined CAD, whereas IgG OxLDL autoantibodies and IgG apoB-ICs were positively associated. In logistic regression analysis, compared with the first quartile, patients in the fourth quartile of IgM OxLDL autoantibodies and apoB-ICs showed a lower probability of angiographically determined CAD (>50% diameter stenosis). Odds ratios and (95% confidence intervals) were as follows: MDA-LDL, 0.51 (0.32-0.82; P = 0.005); CuOxLDL, 0.63 (0.39-1.01; P = 0.05); OxCL, 0.63 (0.39-1.01; P = 0.05); and apoB-IC, 0.55 (0.34-0.88; P = 0.013). These relationships were accentuated in the setting of hypercholesterolemia, with the highest IgM levels showing the lowest risk of CAD for the same level of hypercholesterolemia. Multivariable analysis revealed that neither IgM or IgG OxLDL autoantibodies nor apoB-ICs were independently associated with angiographically determined CAD or cardiovascular events. In conclusion, IgG and IgM OxLDL biomarkers have divergent associations with CAD in univariate analysis but are not independent predictors of CAD or clinical events.

Evaluating the AIH Scoring System

Evaluating the AIH Scoring System

Dichotomous effects of complete versus partial class II major histocompatibility complex deficiency on circulating autoantibody levels in autoimmune-prone mice

To assess the effects of altered class II major histocompatibility complex (MHCII) expression on circulating autoantibody levels in C57BL/6 (B6) mice congenic for the Sle1 (B6.Sle1 mice) or Nba2 (B6.Nba2 mice) regions. H-2Ab(+/+) (MHCII-intact), H-2Ab(+/-) (MHCII-intermediate), and H-2Ab(-/-) (MHCII-deficient) littermate B6.Sle1 and B6.Nba2 mice were evaluated for spleen cell phenotype, numbers of splenic Ig-secreting cells, and serum levels of total IgM, total IgG, IgG antichromatin, IgG antihistone, and IgG anti-double-stranded DNA (anti-dsDNA). Compared with their MHCII-intact littermates, MHCII-deficient B6.Sle1 and B6.Nba2 mice developed markedly decreased circulating levels of IgG autoantibodies, along with decreased circulating levels of total IgG. In sharp contrast, MHCII-intermediate mice developed increased circulating levels of IgG autoantibodies. This was associated with increased numbers of splenic Ig-secreting cells and serum levels of total IgG in B6.Sle1 mice, but it occurred without concomitant increases in the numbers of splenic Ig-secreting cells or serum total IgG levels in B6.Nba2 mice. In 2 clinically healthy strains of mice with a genetic proclivity for developing autoantibodies, the effects of class II MHC expression on levels of circulating IgG autoantibodies were found to be complex. In the absence of MHCII expression, circulating IgG autoantibody levels were minimal. With full MHCII expression, circulating IgG autoantibody levels were considerable. With intermediate MHCII expression, circulating IgG autoantibody levels were even greater. These last findings may help explain why heterozygosity at the H-2 locus is associated with increased autoantibody titers and aggravated disease in certain lupus-prone mice.

Neural autoantibodies and neurophysiologic abnormalities in patients exposed to molds in water-damaged buildings.

Adverse health effects of fungal bioaerosols on occupants of water-damaged homes and other buildings have been reported. Recently, it has been suggested that mold exposure causes neurological injury. The authors investigated neurological antibodies and neurophysiological abnormalities in patients exposed to molds at home who developed symptoms of peripheral neuropathy (i.e., numbness, tingling, tremors, and muscle weakness in the extremities). Serum samples were collected and analyzed with the enzyme-linked immunosorbent assay (ELISA) technique for antibodies to myelin basic protein, myelin-associated glycoprotein, ganglioside GM1, sulfatide, myelin oligodendrocyte glycoprotein, alpha-B-crystallin, chondroitin sulfate, tubulin, and neurofilament. Antibodies to molds and mycotoxins were also determined with ELISA, as reported previously. Neurophysiologic evaluations for latency, amplitude, and velocity were performed on 4 motor nerves (median, ulnar, peroneal, and tibial), and for latency and amplitude on 3 sensory nerves (median, ulnar, and sural). Patients with documented, measured exposure to molds had elevated titers of antibodies (immunoglobulin [Ig]A, IgM, and IgG) to neural-specific antigens. Nerve conduction studies revealed 4 patient groupings: (1) mixed sensory-motor polyneuropathy (n = 55, abnormal), (2) motor neuropathy (n = 17, abnormal), (3) sensory neuropathy (n = 27, abnormal), and (4) those with symptoms but no neurophysiological abnormalities (n = 20, normal controls). All groups showed significantly increased autoantibody titers for all isotypes (IgA, IgM, and IgG) of antibodies to neural antigens when compared with 500 healthy controls. Groups 1 through 3 also exhibited abnormal neurophysiologic findings. The authors concluded that exposure to molds in water-damaged buildings increased the risk for development of neural autoantibodies, peripheral neuropathy, and neurophysiologic abnormalities in exposed individuals.

Atherosclerosis, Autoimmunity, and Systemic Lupus Erythematosus

Atherosclerosis can be considered a chronic inflammatory condition of the vessel wall. Fatty streaks, the earliest morphological lesions of atherosclerosis, are caused by lipids (primarily of cholesteryl esters) accumulated within the macrophages (foam cells) and smooth muscle cells in the intimal layer. These lesions progress into atherosclerotic plaques containing extracellular matrix components, smooth muscle cells, macrophages, connective tissues, lymphocytes, and a fibrous cap over a pool of extracellular lipid. The primary pathogenic event in atherosclerosis is not clear. The “response to injury hypothesis” postulates that long-term endothelial cell injury, from a variety of mechanisms, alters endothelial permeability and induces leukocyte and platelet adhesion.1 The release of mitogenic factors from platelets and leukocytes was proposed to induce the migration and proliferation of smooth muscle cells from the media. The “lipid hypothesis” proposes that the retention and oxidation of LDL in the subendothelium play a central role in the atherosclerotic process.2,3 The uptake of oxidatively modified LDL by the macrophage via the scavenger receptor induces foam cell formation, but unmodified native LDL has no effect. Products of LDL oxidation, such as oxidized cholesterol, phospholipids, and isoprostanes have been detected in atherosclerotic plaques.4 Oxidized LDL has a number of pro-atherogenic effects, such as being chemotactic to monocytes and T cells, promoting inflammatory gene expression in vascular cells, and inducing the expression of the macrophage scavenger receptor. …

Complete congenital heart block is associated with increased autoantibody titers against calreticulin.

Complete congenital heart block (CCHB) is associated with anti-Ro/SS-A and anti-La/SS-B antibodies. Calreticulin, a calcium-binding, multi-functional protein of the endoplasmic reticulum with C-terminal KDEL-sequence, is not part of the Ro/SS-A ribonucleoprotein complex. In this study anti-calreticulin autoantibody responses in serum samples from 18 infants with CCHB, their mothers and in a control group of 11 anti-Ro/SS-A or anti-La/SS-B positive infants without heart block and their mothers were analysed. Specific enzyme-linked immunosorbent assays were performed. Nine out of 18 sera with CCHB contained IgG anti-calreticulin antibodies. Four sera of those with IgG antibodies also had IgM antibodies. One serum contained anti-calreticulin IgM antibodies only. In the non-CCHB group two sera were positive for IgG and one serum was positive for IgM anti-calreticulin antibodies. Sera of healthy infants were negative both for anti-IgG and anti-IgM calreticulin antibodies. Calreticulin is involved in calcium storage and therefore anti-calreticulin antibodies might influence the development of CCHB. The new finding of IgM autoantibodies and the observed differences in antibody response in infants and mothers support the hypothesis of a fetally mediated and passively acquired autoimmune disease.