Nephritogenic autoantibodies but absence of nephritis in Il-12p35–deficient mice with pristane-induced lupus

Nephritogenic autoantibodies but absence of nephritis in Il-12p35–deficient mice with pristane-induced lupus.BackgroundThere is strong evidence that Th1 cytokines are essential for disease in murine models of lupus. Interleukin-12 (IL-12) is essential for Th1 cell differentiation and induces interferon-γ (IFN-γ) production. Paradoxically, it has been suggested that an IL-12 defect drives the pathogenesis of lupus, although its precise role remains unclear. We investigated the role of IL-12 for lupus-like disease induced by pristane. IL-12p35–deficient (-/-) and control (+/+) BALB/c mice were treated with pristane or phosphate-buffered saline (PBS).MethodsProteinuria was measured and renal pathology evaluated 10 months after treatment. Sera were analyzed for autoantibodies and total immunoglobulin levels. Cytokine expression and production was analyzed.ResultsPristane induced nephritogenic autoantibodies and renal immunoglobulin and complement deposition in both IL-12 -/- and +/+ mice. However, proliferative pathology and proteinuria were absent in IL-12-/- mice, whereas pristane induced severe nephritis in one third of the +/+ mice. As expected, cytokine balance was skewed toward a Th2 response in pristane-treated IL-12 -/- mice.ConclusionThese data indicate that renal immune complex deposition can occur in the absence of IL-12p35, but that structural renal damage requires the presence of IL-12p35 or mediators induced by this molecule, such as IFN-γ. In contrast to the abrogation of nephritogenic autoantibodies by the lack of IFN-γ, such antibodies are induced by pristane in IL-12p35–deficient mice. Absence of structural renal disease, despite the presence of nephritogenic autoantibodies in pristane-treated IL-12-/- mice, indicates that antibody deposition alone is not sufficient for the development of lupus nephritis in this model

Autoantibodies against the replication protein A complex in systemic lupus erythematosus and other autoimmune diseases

Replication protein A (RPA), a heterotrimer with subunits of molecular masses 70, 32, and 14 kDa, is a single-stranded-DNA-binding factor involved in DNA replication, repair, and recombination. There have been only three reported cases of anti-RPA in systemic lupus erythematosus (SLE) and Sjögren syndrome (SjS). This study sought to clarify the clinical significance of autoantibodies against RPA. Sera from 1,119 patients enrolled during the period 2000 to 2005 were screened by immunoprecipitation (IP) of (35)S-labeled K562 cell extract. Antigen-capture ELISA with anti-RPA32 mAb, immunofluorescent antinuclear antibodies (ANA) and western blot analysis with purified RPA were also performed. Our results show that nine sera immunoprecipitated the RPA70–RPA32–RPA14 complex and all were strongly positive by ELISA (titers 1:62,500 to 1:312,500). No additional sera were positive by ELISA and subsequently confirmed by IP or western blotting. All sera showed fine speckled/homogeneous nuclear staining. Anti-RPA was found in 1.4% (4/276) of SLE and 2.5% (1/40) of SjS sera, but not in rheumatoid arthritis (0/35), systemic sclerosis (0/47), or polymyositis/dermatomyositis (0/43). Eight of nine patients were female and there was no racial predilection. Other positive patients had interstitial lung disease, autoimmune thyroiditis/hepatitis C virus/pernicious anemia, or an unknown diagnosis. Autoantibody specificities found in up to 40% of SLE and other diseases, such as anti-nRNP, anti-Sm, anti-Ro, and anti-La, were unusual in anti-RPA-positive sera. Only one of nine had anti-Ro, and zero of nine had anti-nRNP, anti-Sm, anti-La, or anti-ribosomal P antibodies. In summary, high titers of anti-RPA antibodies were found in nine patients (1.4% of SLE and other diseases). Other autoantibodies found in SLE were rare in this subset, suggesting that patients with anti-RPA may form a unique clinical and immunological subset

Interferon-γ is required for lupus nephritis in mice treated with the hydrocarbon oil pristane

BACKGROUND: Although the precise mechanisms leading to lupus nephritis remain obscure, both TH1 and TH2 cytokines have been implicated. The present study examined the roles of interleukin (IL)-4 and interferon-gamma (IFN-gamma) in a novel inducible form of lupus that develops in non-autoimmune mice treated with the hydrocarbon oil pristane. METHODS: BALB/c IL-4 or IFN-gamma deficient mice (IL-4 -/-, IFNgamma -/-) and wild type controls (+/+) received either pristane or phosphate-buffered saline (PBS) IP. Serial sera were analyzed for anti-DNA/chromatin, anti-RNP/Sm, and total immunoglobulin levels. Proteinuria was measured and kidneys were examined by direct immunofluorescence and light microscopy. RESULTS: Renal disease did not develop in pristane-treated IFN-gamma -/- mice, as assessed by the absence of capillary immune deposits, glomerular pathology and proteinuria whereas IL-4 -/- mice developed renal disease similar to +/+ mice. Production of IgG anti-single stranded DNA and anti-chromatin antibodies was abrogated in IFN-gamma -/- mice. In contrast, these autoantibodies were produced at similar or higher frequencies and levels by IL-4 -/- versus wild-type mice. The frequency of anti-nRNP/Sm was markedly reduced in IFN-gamma -/- mice. IL-4 deficiency had little effect on the production of anti-DNA/chromatin and anti-nRNP/Sm. CONCLUSIONS: IFN-gamma is essential for the induction of nephritis and anti-DNA/chromatin following pristane exposure in BALB/c mice, suggesting that genetic or environmental factors influencing TH1-TH2 balance could be an important determinant of renal disease in lupus

Modeling resilience and sustainability in ancient agricultural systems

The reasons why people adopt unsustainable agricultural practices, and the ultimate environmental implications of those practices, remain incompletely understood in the present world. Archaeology, however, offers unique datasets on coincident cultural and ecological change, and their social and environmental effects. This article applies concepts derived from ecological resilience thinking to assess the sustainability of agricultural practices as a result of long-term interactions between political, economic, and environmental systems. Using the urban center of Gordion, in central Turkey, as a case study, it is possible to identify mismatched social and ecological processes on temporal, spatial, and organizational scales, which help to resolve thresholds of resilience. Results of this analysis implicate temporal and spatial mismatches as a cause for local environmental degradation, and increasing extralocal economic pressures as an ultimate cause for the adoption of unsustainable land-use practices. This analysis suggests that a research approach that integrates environmental archaeology with a resilience perspective has considerable potential for explicating regional patterns of agricultural change and environmental degradation in the past

Autoantibodies Define a Family of Proteins with Conserved Double-stranded RNA-binding Domains as Well as DNA Binding Activity

Cellular responses to viral infection are signaled by double-stranded (ds) RNA, which is not found in substantial amounts in uninfected cells. Although cellular dsRNA-binding proteins have been described, their characterization is incomplete. We show that dsRNA-binding proteins are prominent autoantigens. Sera from B6 and B10.S mice with pristane-induced lupus and human autoimmune sera immunoprecipitated a novel set of 130-, 110-, 90-, 80-, and 45-kDa proteins. The proteins were all major cellular poly(IC)-binding factors. N-terminal amino acid sequences of p110 and p90 were identical and matched nuclear factor (NF) 90 and M phase phosphoprotein 4. p45 and p90 were identified as the NF45.NF90 complex, which binds the interleukin-2 promoter as well as certain highly structured viral RNAs. NF90.NF45 and M phase phosphoprotein 4 belong to a large group of proteins with conserved dsRNA-binding motifs. Besides binding dsRNA, NF90.NF45, p110, and p130 had single-stranded and dsDNA binding activity. Some sera contained autoantibodies whose binding was inhibited by poly(IC) but not single-stranded DNA or vice versa, suggesting that the DNA- and RNA-binding sites are different. These autoantibodies will be useful probes of the function of dsRNA-binding proteins. Their interaction with dsRNA, an immunological adjuvant, also could promote autoimmunity

Increased expression of FcγRI/CD64 on circulating monocytes parallels ongoing inflammation and nephritis in lupus

INTRODUCTION: The high-affinity receptor for IgG Fcγ/CD64 is critical for the development of lupus nephritis (LN). Cross-linking Fc receptor on recruited monocytes by IgG-containing immune complexes is a key step in immune-complex-mediated nephritis in systemic lupus erythematosus (SLE). The goal of this study was to determine whether expression of Fc receptor (FcγR) I on circulating monocytes is associated with systemic inflammation and renal disease in SLE patients. METHODS: We studied 205 SLE patients (132 with LN and 73 without LN) along with 74 healthy control individuals. Surface expression of CD14 (monocytes), FcγRI/CD64, FcγRII/CD32, and FcγRIII/CD16 was evaluated by flow cytometry. Monocyte function was assessed by determining the migratory capacity and the ability to produce CCL2 (monocyte chemotractic protein 1). High-sensitivity C-reactive protein, C3 and C4 were measured by nephelometry. RESULTS: There was little difference in the expression of FcγRIII/CD16 or FcγRIII/CD32 on circulating monocytes between patients with SLE and control individuals. In contrast, FcγRI/CD64 expression was significantly higher in SLE patients and even higher in patients with LN. FcγRI/CD64 expression was positively associated with serum creatinine and indicators of systemic inflammation. Monocytes from patients with high FcγRI/CD64 expression also exhibited increased chemotaxis and capacity to produce monocyte chemotractic protein 1. CONCLUSIONS: Increased FcγRI/CD64 expression on circulating monocytes parallels systemic inflammation and renal disease in SLE patients. We propose that circulating monocytes activated by immune complexes and/or proinflammatory mediators upregulate surface expression of FcγRI/CD64 in SLE. The enhanced chemotactic and inflammatory potential of the activated monocytes may participate in a vicious cycle of immune cell recruitment and renal injury in SLE