Nucleic acid-containing amyloid fibrils potently induce type I interferon and stimulate systemic autoimmunity

Departments of Immunology and Veterinary Medicine and Surgery, University of Texas MD Anderson Cancer Center, Houston, TX 77030.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 09/2012; 109(36):14550-14555. DOI: 10.1073/pnas.1206923109
Source: PubMed


The immunopathophysiologic development of systemic autoimmunity involves numerous factors through complex mechanisms that
are not fully understood. In systemic lupus erythematosus, type I IFN (IFN-I) produced by plasmacytoid dendritic cells (pDCs)
critically promotes the autoimmunity through its pleiotropic effects on immune cells. However, the host-derived factors that
enable abnormal IFN-I production and initial immune tolerance breakdown are largely unknown. Previously, we found that amyloid
precursor proteins form amyloid fibrils in the presence of nucleic acids. Here we report that nucleic acid-containing amyloid
fibrils can potently activate pDCs and enable IFN-I production in response to self-DNA, self-RNA, and dead cell debris. pDCs
can take up DNA-containing amyloid fibrils, which are retained in the early endosomes to activate TLR9, leading to high IFNα/β
production. In mice treated with DNA-containing amyloid fibrils, a rapid IFN response correlated with pDC infiltration and
activation. Immunization of nonautoimmune mice with DNA-containing amyloid fibrils induced antinuclear serology against a
panel of self-antigens. The mice exhibited positive proteinuria and deposited antibodies in their kidneys. Intriguingly, pDC
depletion obstructed IFN-I response and selectively abolished autoantibody generation. Our study reveals an innate immune
function of nucleic acid-containing amyloid fibrils and provides a potential link between compromised protein homeostasis
and autoimmunity via a pDC-IFN axis.

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Available from: Dipyaman Ganguly, Sep 30, 2015
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    • "To date, it is a well established fact that susceptible individuals have a complex multigenic predisposition and that environmental triggers i.e. enteroviral infections may lead to enhanced beta-cell apoptosis, dendritic cell (DC) activation and subsequent T-cell priming [8]. Immune complexes containing self nucleic acids, DNA or RNA, contribute to autoimmunity in systemic lupus erythematosus, psoriasis, polyarthritis, and diabetes [9]–[11]. Aberrant miRNA expression patterns have been associated with disease progression in T1D patients [12], [13]. "
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    ABSTRACT: In addition to important regulatory roles in gene expression through RNA interference, it has recently been shown that microRNAs display immune stimulatory effects through direct interaction with receptors of innate immunity of the Toll-like receptor family, aggravating neuronal damage and tumour growth. Yet no evidence exists on consequences of microRNA immune stimulatory actions in the context of an autoimmune disease. Using microRNA analogues, we here show that pancreatic beta cell-derived microRNA sequences induce pro-inflammatory (TNFa, IFNa, IL-12, IL-6) or suppressive (IL-10) cytokine secretion by primary mouse dendritic cells in a sequence-dependent manner. For miR-29b, immune stimulation in RAW264.7 macrophages involved the endosomal Toll-like receptor-7, independently of the canonical RNA interference pathway. In vivo, the systemic delivery of miR-29b activates CD11b+B220- myeloid and CD11b-B220+ plasmacytoid dendritic cells and induces IFNa, TNFa and IL-6 production in the serum of recipient mice. Strikingly, in a murine model of adoptive transfer of autoimmune diabetes, miR-29b reduces the cytolytic activity of transferred effector CD8+ T-cells, insulitis and disease incidence in a single standalone intervention. Endogenous miR-29b, spontaneously released from beta-cells within exosomes, stimulates TNFa secretion from spleen cells isolated from diabetes-prone NOD mice in vitro. Hence, microRNA sequences modulate innate and ongoing adaptive immune responses raising the question of their potential role in the breakdown of tolerance and opening up new applications for microRNA-based immune therapy.
    PLoS ONE 09/2014; 9(9):e106153. DOI:10.1371/journal.pone.0106153 · 3.23 Impact Factor
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    • "When inoculated into the peritoneal cavity, DNA-containing amyloid fibrils induced selective pDC infiltration, which was associated with a predominant type I IFN response. After immunization with DNA-containing amyloid fibrils, non-autoimmune mice developed stable anti-nuclear autoantibodies and abroad autoreactive humoral response against DNA, RNA, Sm/RNP, and histone [145]. Proteinuria and antibody depositions in the glomeruli of the kidneys were also detected, suggesting the development of a lupus-like syndrome. "
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    ABSTRACT: Plasmacytoid dendritic cells (pDCs) were initially identified as the prominent natural type I interferon-producing cells during viral infection. Over the past decade, the aberrant production of interferon α/β by pDCs in response to self-derived molecular entities has been critically implicated in the pathogenesis of systemic lupus erythematosus and recognized as a general feature underlying other autoimmune diseases. On top of imperative studies on human pDCs, the functional involvement and mechanism by which the pDC-interferon α/β pathway facilitates the progression of autoimmunity have been unraveled recently from investigations with several experimental lupus models. This article reviews correlating information obtained from human in vitro characterization and murine in vivo studies and highlights the fundamental and multifaceted contribution of pDCs to the pathogenesis of systemic autoimmune manifestation.
    04/2014; 5(2):212. DOI:10.4172/2155-9899.1000212
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    • "Recently we observed that the precursor form of amyloid, soluble protein oligomers, can efficiently bind DNA converting them into amyloids [20]. Strikingly, these nucleic acid-containing amyloids could initiate inflammation and their injection to non-autoimmune mice lead to a broad anti-autoantigen response with the generation of anti-DNA autoantibodies [21]. "
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    ABSTRACT: The mechanistic study of inflammatory or autoimmune diseases requires the generation of mouse models that reproduce the alterations in immune responses observed in patients. Methylated bovine serum albumin (mBSA) has been widely used to induce antigen-specific inflammation in targeted organs or in combination with single stranded DNA (ssDNA) to generate anti-nucleic acids antibodies in vivo. However, the mechanism by which this modified protein triggers inflammation is poorly understood. By analyzing the biochemical properties of mBSA, we found that mBSA exhibits features of an intermediate of protein misfolding pathway. mBSA readily interact with a list of dyes that have binding specificity towards amyloid fibrils. Intriguingly, mBSA displayed cytotoxic activity and its binding to ssDNA further enhanced formation of beta-sheet rich amyloid fibrils. Moreover, mBSA is recognized by the serum amyloid P, a protein unanimously associated with amyloid plaques in vivo. In macrophages, we observed that mBSA disrupted the lysosomal compartment, signaled along the NLRP3 inflammasome pathway, and activated caspase 1, which led to the production of IL-1β. In vivo, mBSA triggered rapid and prominent immune cell infiltration that is dependent on IL-1β induction. Taken together, these data demonstrate that by mimicking amyloidogenic proteins mBSA exhibits strong innate immune functions and serves as a potent adjuvant. These findings advance our understanding on the underlying mechanism of how aberrant immune responses lead to autoimmune reactions.
    PLoS ONE 05/2013; 8(5):e63214. DOI:10.1371/journal.pone.0063214 · 3.23 Impact Factor
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