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Interferon‐β inhibits toll‐like receptor 9 processing in multiple sclerosis
Author(s) -
Balashov Konstantin E.,
Aung Latt Latt,
VakninDembinsky Adi,
DhibJalbut Suhayl,
Weiner Howard L.
Publication year - 2010
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.22136
Subject(s) - tlr9 , interferon , cytokine , proinflammatory cytokine , immunology , multiple sclerosis , receptor , pathogenesis , tumor necrosis factor alpha , toll like receptor 9 , medicine , biology , inflammation , gene expression , gene , dna methylation , biochemistry
Objective Viral infections have been implicated in the pathogenesis of multiple sclerosis (MS). Plasmacytoid dendritic cells (pDCs) are present in peripheral blood, cerebrospinal fluid, and brain lesions of MS patients. pDCs sense viral DNA via Toll‐like receptor 9 (TLR9), which has to be cleaved from the N‐terminal to become functional (TLR9 processing). pDCs activated with TLR9 agonists promote T‐helper type 1 (Th1)/T‐helper type 17 (Th17) responses. In the animal model of MS, TLR9 agonists can induce disease. We hypothesized that pDCs are inhibited by disease‐modifying therapy such as interferon (IFN)‐β, consequently decreasing the frequency of MS attacks. Methods We separated pDCs from healthy subjects and patients diagnosed with relapsing‐remitting MS and clinically isolated syndrome. Cytokine secretion by pDCs activated with TLR9 agonists was measured by enzyme‐linked immunosorbent assay and multianalyte profiling. TLR9 gene and protein expression was studied by DNA microarrays and western blot. Results In untreated patients, pDCs activated with TLR9 agonists produced increased levels of IFN‐α, a Th1‐promoting cytokine, as compared to healthy subjects. In IFN‐β‐treated patients, activated pDCs had decreased ability to produce both IFN‐α and the proinflammatory cytokines interleukin (IL)‐6 and tumor necrosis factor α as compared to untreated patients. pDCs separated from IFN‐β‐treated patients had significantly reduced levels of the processed TLR9 protein but normal levels of the full‐length TLR9 protein and TLR9 gene expression as compared to untreated patients. Interpretation This finding represents a novel immunomodulatory mechanism of IFN‐β: inhibition of TLR9 processing. This results in decreased activation of pDCs by viral pathogens and, thus, may affect the frequency of MS exacerbations. ANN NEUROL 2010