Géraldine Falgarone

Vitamin D and inflammation.

Calcitriol, or 1,25-dihydroxyvitamin D3 (1,25(OH)(2)D3) is a well-known endocrine regulator of calcium homeostasis. More recently, local calcitriol production by immune cells was shown to exert autocrine or paracrine immunomodulating effects. Immune cells that produce calcitriol also express the vitamin D receptor (VDR) and the enzymes needed to metabolize vitamin D3 (1α-, 25-, and 24-hydroxylases). Studies of animal models and cell cultures showed both direct and indirect immunomodulating effects involving the T cells, B cells, and antigen-presenting cells (dendritic cells and macrophages) and affecting both innate and adaptive immune responses. The overall effect is a switch from the Th1/Th17 response to the Th2/Treg profile. The immunomodulating effects of vitamin D may explain the reported epidemiological associations between vitamin D status and a large number of autoimmune and inflammatory diseases. Such associations have been suggested by observational studies not only in rheumatoid arthritis, lupus, inflammatory bowel disease, and type 1 diabetes; but also in infections, malignancies, transplant rejection, and cardiovascular disease. In animal models for these diseases, vitamin D supplementation has been found to produce therapeutic effects. Thus, vitamin D is a key focus for public health efforts and may hold promise for the treatment of dysimmune diseases.

Rheumatoid arthritis: from autoimmunity to synovitis and joint destruction.

Rheumatoid arthritis is an autoimmune disease characterized by the production of two known antibodies - rheumatoid factor and anti-citrullinated peptide antibody (ACPA) - against common autoantigens that are widely expressed within and outside the joints. The interactions between genes and environment are crucial in all stages of the disease, involving namely genes from major histocompatibility complex locus, and antigens such as tobacco or microbes (e.g. Porphyromonas gingivalis). T and B cells are activated as soon as the earliest phases of the disease, rheumatoid arthritis appearing as a Th1 and Th17 disease. Inflammatory cytokines have a considerable importance in the hierarchy of the processes involved in RA. The joint destruction seen in RA is caused not only by cytokine imbalances, but also by specific effects of the Wnt system and osteoprotegerin on osteoclasts and by matrix production dysregulation responsible for cartilage damage. Both innate and adaptative immunity demonstrated their respective cornerstone position in rheumatoid arthritis, since targeted treatments has been efficiently developed against TNF-α, IL-6 receptor, IL-1β, CD20 B cells and T-cell/Dendritic cell interactions.

Interleukin-23: A key cytokine in inflammatory diseases

Abstract Interleukin-23 (IL-23) is a pro-inflammatory cytokine composed of two subunits, p19 and p40. The p40 subunit is shared with IL-12. IL-23 and IL-12 have different receptors and different effects. Whereas IL-12 induces development of Th1 cells, which produce interferon-γ, IL-23 is involved in differentiation of Th17 cells in a pro-inflammatory context and especially in the presence of TGF-β and IL-6. Activated Th17 cells produce IL-17A, IL-17F, IL-6, IL-22, TNF-α, and GM-CSF. Inflammatory macrophages express IL-23R and are activated by IL-23 to produce IL-1, TNF-α, and IL-23 itself. These effects identify IL-23 as a central cytokine in autoimmunity and a highly promising treatment target for inflammatory diseases. IL-23 is found in the skin of patients with psoriasis, in the bowel wall of patients with chronic inflammatory bowel disease, and in synovial membrane of patients with rheumatoid arthritis. IL-23 is involved in osteoclastogenesis, independently from IL-17, via induction of RANKL expression. Debate continues to surround the role for IL-23 in the pathophysiology of inflammatory joint diseases (rheumatoid arthritis and spondyloarthritis). Ustekinumab, which inhibits IL-12 and IL-23 by blocking p40, has been found effective in cutaneous psoriasis and psoriatic arthritis, as well as in Crohns disease. Treatments that specifically target IL-23 (antibodies to p19) are being developed.

Regulatory T cells (Treg) in rheumatoid arthritis

Modulation of the T-cell response depends chiefly on regulatory T cells (Treg), which express CD4 and CD25. Some Treg cells are present naturally, whereas others are induced in response to antigens. The immunomodulating effects of Treg cells are mediated by membrane molecules (e.g., CTLA4, GITR, and OX40) and cytokines. IL-35 seems to be a crucial mediator, although IL-10 and TGFbeta are also important. The role for Treg cells in rheumatoid arthritis (RA) has been established in both patients and animal models. Treg function is deficient in RA, whereas Treg counts vary. Treg counts increase in patients who are responding to TNFalpha antagonist therapy. Among current hypotheses, Treg expansion or transfer may hold promise for the treatment of RA.

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.

Chapter 8: Clusterin: A multifacet protein at the crossroad of inflammation and autoimmunity.

For years, clusterin has been recognized as a secreted protein and a large number of works demonstrated that this ubiquitously expressed protein has multiple activities. Among the described activities several were related to inflammation and immunity such as its regulatory activity on complement. Then it became clear that a nuclear form of the protein with proapoptotic property existed and more recently that a cytoplasmic form could regulate NF-kappaB pathway. Again, these activities have a strong repercussion in inflammation and immunity. On the other hand, data available on the exact role of CLU in these processes and autoimmunity were quite scarce until recently. Indeed, in the last few years, a differential CLU expression in subtype of T cells, the regulation of CLU expression by proinflammatory cytokines and molecules, the regulation of expression and function of CLU depending on its subcellular localization, the interaction of CLU with nuclear and intracellular proteins were all reported. Adding these new roles of CLU to the already reported functions of this protein allows a better understanding of its role and potential involvement in several inflammatory and immunological processes and, in particular, autoimmunity. In this sense, rheumatoid arthritis appears to be a very attractive disease to build a new paradigm of the role and function of CLU because it makes the link between proliferation, inflammation, and autoimmunity. We will try to see in this review how to bring altogether the old and new knowledge on CLU with inflammation and autoimmunity. Nevertheless, it is clear that CLU has not yet revealed all its secrets in inflammation and autoimmunity.

Immune Response Against Gene Therapy Vectors: Influence of Synovial Fluid on Adeno-Associated Virus Mediated Gene Transfer to Chondrocytes

Intraarticular gene transfer with adeno-associated virus (AAV) vectors may allow efficient therapeutic transgene expression within the joint. In an effort to understand potential obstacles (particularly immunity against AAV vectors) to intraarticular gene therapy better, our objective was to determine whether synovial fluid (SF) influenced AAV-mediated gene transfer to chondrocytes. SF and sera from 21 patients with joint diseases were collected. Neutralizing activity against AAV/interleukin-4 (IL-4) was determined by assessing the ability of SF or serum to inhibit AAV/IL-4 transduction to the C20A4 chondrocytes. IgGs were purified from SF by salt-dependent chromatography. Anti-AAV IgG levels were determined by ELISA in the SF. SF and sera from all the patients inhibited AAV-mediated gene transfer to chondrocytes. Six SF out of 21 exerted a stronger inhibition. Serum from healthy patients were also inhibitory. Purified IgGs from SF exhibited inhibition patterns similar to those seen with whole SF. Anti-AAV IgG were found in SF from 13 patients out of 18. Moreover, in the SF, anti-AAV IgG level was correlated with the neutralizing activity (p < 0.001, r = 0.716). A correlation was observed between levels of inhibition by the SF and serum (P < 0.0001, r = 0.813). Inhibition of AAV/IL-4 infection of C20A4 cells by SF and sera was abolished by increasing the number of AAV/IL-4 particles. SF from patients with joint disease consistently inhibited AAV infection of chondrocytes in vitro. This effect was ascribable to IgG, most probably directed against AAV. In the future, these data may be useful for tailoring intraarticular AAV-mediated gene therapy to individual patients.

Epidemiology of Primary Sjögren's Syndrome in a French Multiracial/Multiethnic Area

To describe the epidemiology of primary Sjögrens syndrome (SS) in a multiracial/multiethnic population.

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.

Systemic inflammatory and autoimmune manifestations associated with myelodysplastic syndromes and chronic myelomonocytic leukaemia: a French multicentre retrospective study

OBJECTIVE We describe myelodysplastic syndrome (MDS)-associated systemic inflammatory and autoimmune diseases (SIADs), their treatments and outcomes and the impact of SIADs on overall survival in a French multicentre retrospective study. METHODS In this study, 123 patients with MDS and SIADs were analysed. RESULTS Mean age was 70 years (s.d. 13) and the male:female ratio was 2. The SIADs were systemic vasculitis in 39 (32%) cases, CTD in 31 (25%) cases, inflammatory arthritis in 28 (23%) cases, a neutrophilic disorder in 12 (10%) cases and unclassified in 13 cases (11%). The SIADs fulfilled the usual classification criteria in 75 (66%) cases, while complete criteria were not reached in 21 (19%) cases. A significant association was shown between chronic myelomonocytic leukaemia (CMML) and systemic vasculitis (P = 0.0024). One hundred and eighteen (96%) SIAD patients were treated (91% with steroids), with an 83% response to first-line treatment, including 80% for steroids alone. A second-line treatment for SIADs was required for steroid dependence or relapse in 48% of cases. The effect of MDS treatment on SIADs could be assessed in 11 patients treated with azacytidine and SIAD response was achieved in 9/11 (80%) and 6/11 (55%) patients at 3 and 6 months, respectively. Compared with 665 MDS/CMML patients without SIADs, MDS/CMML patients with SIADs were younger (P < 0.01), male (P = 0.03), less often had refractory anaemia with ring sideroblasts (P < 0.01), more often had a poor karyotype (16% vs 11%, P = 0.04) and less frequently belonged to low and intermediate-1 International Prognostic Scoring System categories, but no survival difference was seen between patients with MDS-associated SIADs and without SIADs (P = 0.5). CONCLUSION The spectrum of SIADs associated to MDS is heterogeneous, steroid sensitive, but often steroid dependent.