Olivier Jaen

Dendritic cells modulated by innate immunity improve collagen‐induced arthritis and induce regulatory T cells in vivo

Dendritic cells (DCs) mediate interactions between innate and specific immunity and may induce regulatory mechanisms. We investigated the effects of modulated DCs in mice with collagen‐induced arthritis (CIA) and tested the responses of cells to induced naturally occurring regulatory T cells. DCs were stimulated or not with DNA or lipopolysaccharide (LPS) for 24 hr. DC maturation was assayed, and then modulated DCs were intraperitoneally injected on day 14 into DBA/1 mice to treat CIA. In addition to arthritis scores and type 2 collagen (CII) response, the induction of CD4+ CD25+ T cells was analysed by flow cytometry in peripheral blood and the expression of Foxp3, transforming growth factor (TGF)‐β, interleukin (IL)‐10 and cytotoxic T‐lymphocyte antigen (CTLA)‐4 was quantified. Finally, the expression of indoleamine‐2,3‐dioxygenase (IDO) was assayed in DCs. In comparison with LPS‐stimulated DCs, plasmid‐stimulated DCs expressed lower levels of major histocompatibility complex (MHC) class II, CD40, CD80 and CD86 molecules and secreted less IL‐12p70, interferon (IFN)‐γ, IL‐10 and TNF‐α, displaying a semi‐mature phenotype. Compared with non‐stimulated DCs, stimulated DCs improved arthritis scores when injected after immunization, without modifying the T helper type 1 (Th1)/Th2 balance of the immune response against collagen. Stimulated DCs induced markers for regulatory T cells (Foxp3, TGF‐β1 and CTLA‐4) in vivo. Only LPS‐stimulated DCs expressed IDO, which may explain their better therapeutic efficacy. Regulatory mechanisms were induced using DCs modulated by innate immunity stimulators. Innate immunity mechanisms do not require the presence of the disease‐causing antigen, even in T‐ and B‐cell specific diseases. Our results have implications for the treatment of rheumatoid arthritis, an autoimmune disease whose triggering antigen has not been identified, and substantially clarify the role of regulatory T cells in CIA.

No evidence of major effects in several Toll-like receptor gene polymorphisms in rheumatoid arthritis

IntroductionThe objective was to study the potential genetic contribution of Toll-like receptor (TLR) genes in rheumatoid arthritis (RA). TLRs bind to pathogen-associated molecular patterns, and TLR genes influence both proinflammatory cytokine production and autoimmune responses. Host–pathogen interactions are involved in RA physiopathology.MethodsWe tested SNPs of five TLR genes (TLR9, TLR2, TLR6, TLR1, and TLR4) in a cohort of 100 French families with RA. Genotypes were analyzed using the transmission disequilibrium test. As TLR2, TLR6, and TLR1 are located on chromosome 4, we determined the haplotype relative risk. Analyses were performed in subgroups defined by status for rheumatoid factor, anti-cyclic citrullinated peptide autoantibodies, and erosions.ResultsWe found no disequilibrium in allele transmission for any of the SNPs of the five TLR genes. In subgroup analyses, no associations were detected linking TLR9, TLR2, or TLR9/TLR2 to rheumatoid factor, anti-cyclic citrullinated peptide autoantibodies, or erosions. Haplotype analysis of the polymorphisms showed no haplotype associations in any of the subgroups.ConclusionsWe found no evidence of major effects of TLR gene polymorphisms in RA, although we tested different TLR phenotypes. Moreover, no associations were noted with autoantibody production or erosions.

In vivo induction of foxp3 in collagen-induced arthritis treatment with modified dendritic cells

We studied the prevention of a mice model of rheumatoid arthritis, the collagen-induced arthritis (CIA) model, with DNA-matured dendritic cell injection and then studied the induction of Treg through this innate immunity stimulation. CIA was induced as described in DBA/1 mice with bovine type II collagen intradermal injections. Intermediate DNA-matured dendritic cells were injected at D14 intraperitoneally. The clinical course of arthritis was followed and B-cell and T-cell responses were assayed. The induction of CD4+CD25+ was tested by flow cytometry and the induction of Treg markers was quantified by quantitative RT-PCR. Treatment of CIA with intermediate DNA-matured dendritic cells could prevent arthritis as well as lipopolysaccharide-matured dendritic cells. Neither B-cell and T-cell responses were not modified nor was a TH2 response observed. The induction of Treg (CD4+CD25+) cells was observed in blood, and lymph nodes. The induction of foxp3 could be quantified and increased with DNA-matured dendritic cells in peripheral nodes. In conclusion we observed a prevention of CIA with the injection of DNA-matured dendritic cells that did not modify the specific response against bovine type II collagen. Because of the absence of T-cell and B-cell response modification as well as TH2 modification, we believed that the induction of CD4+CD25+ cells that expressed foxp3 are involved in the prevention of CIA we observed.