Dysfunctional interferon-α production by peripheral plasmacytoid dendritic cells upon Toll-like receptor-9 stimulation in patients with systemic lupus erythematosus

Department of Medicine, Division of Rheumatology, Center for Rheumatic Diseases and Rheumatism Research Center, Catholic Research Institutes of Medical Sciences, Catholic University of Korea, Seoul.
Arthritis research & therapy (Impact Factor: 3.75). 02/2008; 10(2):R29. DOI: 10.1186/ar2382
Source: PubMed


It is well known that interferon (IFN)-alpha is important to the pathogenesis of systemic lupus erythematosus (SLE). However, several reports have indicated that the number of IFN-alpha producing cells are decreased or that their function is defective in patients with SLE. We studied the function of plasmacytoid dendritic cells (pDCs) under persistent stimulation of Toll-like receptor (TLR)9 via a TLR9 ligand (CpG ODN2216) or SLE serum.
The concentrations of IFN-alpha were determined in serum and culture supernatant of peripheral blood mononuclear cells (PBMCs) from SLE patients and healthy controls after stimulation with CpG ODN2216 or SLE serum. The numbers of circulating pDCs were analyzed by fluoresence-activated cell sorting analysis. pDCs were treated with CpG ODN2216 and SLE serum repeatedly, and levels of produced IFN-alpha were measured. The expression of IFN-alpha signature genes and inhibitory molecules of TLR signaling were examined in PBMCs from SLE patients and healthy control individuals.
Although there was no significant difference in serum concentration of IFN-alpha and number of circulating pDCs between SLE patients and healthy control individuals, the IFN-alpha producing capacity of PBMCs was significantly reduced in SLE patients. Interestingly, the degree which TLR9 ligand-induced IFN-alpha production in SLE PBMCs was inversely correlated with the SLE serum-induced production of IFN-alpha in healthy PMBCs. Because repeated stimulation pDCs with TLR9 ligands showed decreased level of IFN-alpha production, continuous TLR9 stimulation may lead to decreased production of IFN-alpha in SLE PBMCs. In addition, PBMCs isolated from SLE patients exhibited higher expression of IFN-alpha signature genes and inhibitory molecules of TLR signaling, indicating that these cells had already undergone IFN-alpha stimulation and had become desensitized to TLR signaling.
We suggest that the persistent presence of endogenous IFN-alpha inducing factors induces TLR tolerance in pDCs of SLE patients, leading to impaired production of IFN-alpha.

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Available from: June-Yong Lee, Apr 24, 2014
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    • "The production of IFN-γ by CVID patients PBMCs was also overall reduced when compared to control subjects. Impaired secretion of these cytokines in [55] culture would not exclude excess in vivo production as continued TLR activation leading to pathway activation, may desensitize the relevant cells leading to exhaustion [56]. "
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    ABSTRACT: About half of all subjects with common variable immune deficiency (CVID) are afflicted with inflammatory complications including hematologic autoimmunity, granulomatous infiltrations, interstitial lung disease, lymphoid hyperplasia and/or gastrointestinal inflammatory disease. The pathogenesis of these conditions is poorly understood but singly and in aggregate, these lead to significantly increased (11 fold) morbidity and mortality, not experienced by CVID subjects without these complications. To explore the dysregulated networks in these subjects, we applied whole blood transcriptional profiling to 91 CVID subjects, 47 with inflammatory conditions and 44 without, in comparison to subjects with XLA and healthy controls. As compared to other CVID subjects, males with XLA or healthy controls, the signature of CVID subjects with inflammatory complications was distinguished by a marked up-regulation of IFN responsive genes. Chronic up-regulation of IFN pathways is known to occur in autoimmune disease due to activation of TLRs and other still unclarified cytoplasmic sensors. As subjects with inflammatory complications were also more likely to be lymphopenic, have reduced B cell numbers, and a greater reduction of B, T and plasma cell networks, we suggest that more impaired adaptive immunity in these subjects may lead to chronic activation of innate IFN pathways in response to environmental antigens. The unbiased use of whole blood transcriptome analysis may provides a tool for distinguishing CVID subjects who are at risk for increased morbidity and earlier mortality. As more effective therapeutic options are developed, whole blood transcriptome analyses could also provide an efficient means of monitoring the effects of treatment of the inflammatory phenotype.
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    • "It should be noted that IFN-α measurement was performed only in the BMDC culture supernatants from a few subjects; further studies are needed to confirm this finding. It is interesting to note that a recent study showed that peripheral-blood pDCs from patients with chronic SLE had decreased in vitro IFN-α-producing capacity and were desensitized to TLR9 stimulation [13]. These data, plus those reported previously [3,7,8,13,14] and our current data on BMDCs provide further important insight into the role(s) of pDCs in SLE pathogenesis. "
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    ABSTRACT: Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoreactive T and B cells, which are believed to be secondary to deficient dendritic cells (DCs). However, whether DC abnormalities occur during their development in the bone marrow (BM) or in the periphery is not known. Thirteen patients with SLE and 16 normal controls were recruited. We studied the morphology, phenotype, and functional abilities of bone marrow-derived dendritic cells (BMDCs) generated by using two culture methods: FMS-like tyrosine kinase 3 (Flt3)-ligand (FL) and granulocyte-macrophage colony-stimulating factor (GM-CSF) plus interleukin-4 (IL-4), respectively. BMDCs induced by FL exhibited both myeloid (mDC) and plasmacytoid DC (pDC) features, whereas GM-CSF/IL-4 induced mDC generation. Substantial phenotypic and functional defects of BMDCs were found from patients with SLE at different stages of cell maturation. When compared with healthy controls, SLE immature BM FLDCs expressed higher levels of CCR7. Both immature and mature SLE BM FLDCs expressed higher levels of CD40 and CD86 and induced stronger T-cell proliferation. SLE BM mDCs expressed higher levels of CD40 and CD86 but lower levels of HLA-DR and a lower ability to stimulate T-cell proliferation when compared with control BM mDCs. Our data are in accordance with previous reports that suggest that DCs have a potential pathogenic role in SLE. Defects of these cells are evident during their development in BM. BM mDCs are deficient, whereas BM pDCs, which are part of BM FLDCs, are the likely culprit in inducing autoimmunity in SLE.
    Full-text · Article · May 2010 · Arthritis research & therapy
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    • "In some previous in vitro experiments, stimulation of PBMCs with serum obtained from a patient with SLE induced IFN-α production, and serum containing DNA from necrotic cell supernatant enhanced the IFN-α production [35,36]. Based on these findings, we designed additional experiments using PBMCs and serum from patients with SLE, as described [36,37], to assess whether BAY11 functions as an inhibitor of type I IFN production under the pathophysiological condition of SLE. Initially, PBMCs from SLE patients were stimulated with CpG in the medium containing 20% auto-serum. "
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