Harnessing human dendritic cell subsets for medicine.

Immunity results from a complex interplay between the antigen-non-specific innate immune system and the antigen-specific adaptive immune system. The cells and molecules of the innate system employ non-clonal recognition receptors including lectins, Toll-like receptors, NOD-like receptors, and helicases. B and T lymphocytes of the adaptive immune system employ clonal receptors recognizing antigens or their derived peptides in a highly specific manner. An essential link between innate and adaptive immunity is provided by dendritic cells (DCs). DCs can induce such contrasting states as immunity and tolerance. The recent years have brought a wealth of information on the biology of DCs revealing the complexity of this cell system. Indeed, DC plasticity and subsets are prominent determinants of the type and quality of elicited immune responses. In this article, we summarize our recent studies aimed at a better understanding of the DC system to unravel the pathophysiology of human diseases and design novel human vaccines.

The efficacy of mizoribine for the treatment of rheumatoid arthritis and its correlation with renal function.

OBJECTIVES: To evaluate the correlation between the efficacy of mizoribine (MZR) and the factors that might effect MZR concentration: renal function and dosage and administration of MZR in patients with rheumatoid arthritis (RA). METHODS: The efficacy of MZR treatment was prospectively evaluated in 97 RA regardless of dosage, at the 14 participated institutions. The Disease Activity Score 28-CRP3 was used to assess RA activity. The renal function was evaluated based on the serum creatinine and serum cystatin-C (Cys-C). The patients were followed up for 24 weeks. RESULTS: The patients with a mean age 66.2 years included 18 male. The renal function assessment showed increased creatinine in 16.4% of patients and increased Cys-C in 54.5%, suggesting the higher sensitivity of Cys-C to detect impaired renal function than creatinine. In patients with good or moderate response according to the European League against Rheumatism classification criteria, the Cys-C was significantly higher compared with those with no response. MZR treatment was significantly more effective in patients with an arithmetic product of the single MZR dose used and Cys-C of 179 or more. CONCLUSIONS: The efficacy of MZR may increase in proportion to its single dose, or increased Cys-C level in patients with impaired renal function.

CD2 distinguishes two subsets of human plasmacytoid dendritic cells with distinct phenotype and functions.

Plasmacytoid dendritic cells (pDCs) are key regulators of antiviral immunity. They rapidly secrete IFN-alpha and cross-present viral Ags, thereby launching adaptive immunity. In this study, we show that activated human pDCs inhibit replication of cancer cells and kill them in a contact-dependent fashion. Expression of CD2 distinguishes two pDC subsets with distinct phenotype and function. Both subsets secrete IFN-alpha and express granzyme B and TRAIL. CD2(high) pDCs uniquely express lysozyme and can be found in tonsils and in tumors. Both subsets launch recall T cell responses. However, CD2(high) pDCs secrete higher levels of IL12p40, express higher levels of costimulatory molecule CD80, and are more efficient in triggering proliferation of naive allogeneic T cells. Thus, human blood pDCs are composed of subsets with specific phenotype and functions.

An attack of acute neuro-Behçet's disease during the course of chronic progressive neuro-Behçet's disease: report of two cases.

A 29-year-old man and a 36-year-old man developed attacks of acute neuro-Behçet's disease (NB) (right Horner's syndrome and right hemiplegia and dysarthria, respectively) during the course of chronic progressive NB (acute on chronic). Although both patients recovered from acute NB after treatment with infliximab or corticosteroids, they continued to show manifestations of chronic progressive NB. It is suggested that acute NB and chronic progressive NB are different in their pathogenesis.

Henoch-Schönlein pupura complicated by perforation of the gallbladder.

Henoch-Schönlein purpura is a systemic vasculitis of small vessels characterized by purpura, arthralgias, glomerulonephritis and gastrointestinal involvements which can cause intestinal perforation. A 75-year-old man with renal dysfunction and palpable purpura (petechiae) of which dermal specimen showed leukocytoclastic vasculitis was diagnosed as Henoch-Schönlein purpura. Corticosteroid and cyclosporine were effective, but subsequently he developed pneumocystis pneumonia. After he improved by treatment with trimethoprim-sulfamethoxazole, he presented sudden abdominal pain, caused by perforation of the gallbladder. Histological analysis revealed infiltration of inflammatory cells with bleeding in the gallbladder wall at the site of perforation. It is suggested that inflammatory disruption of capillary walls might lead to the perforation of the gallbladder.

Laser-mediated microdissection for analysis of gene expression in synovial tissue.

In experimental rheumatology, transcriptomics is one of the most important methods for investigating the pathogenesis of diseases. The biological material of most studies on rheumatoid arthritis has been bulk rheumatoid synovial tissues, but they are not suitable because they consist of several kinds of cells or structures. Laser-mediated microdissection (LMM) is a useful tool for isolating particular cells from tissue specimen to assess the functions of each cell. The LMM system employs a combination of a microscope and a laser-beam generator to cut out target areas on cryosections. Tissue compartments or even a single viable cell can be isolated using a non-focused laser beam without direct contact to avoid contamination, and this process is called laser pressure catapulting. An ultraviolet-A laser enables target cells to be procured without any influence on the surrounding. This technique has already been used in several studies in rheumatology, and its validity has been confirmed. Combined with other new techniques such as real-time quantitative polymerase chain reaction or microarray analysis, LMM is becoming more important in the analysis of gene expression in rheumatology.

Dendritic cell subsets in health and disease.

The dendritic cell (DC) system of antigen-presenting cells controls immunity and tolerance. DCs initiate and regulate immune responses in a manner that depends on signals they receive from microbes and their cellular environment. They allow the immune system to make qualitatively distinct responses against different microbial infections. DCs are composed of subsets that express different microbial receptors and express different surface molecules and cytokines. Our studies lead us to propose that interstitial (dermal) DCs preferentially activate humoral immunity, whereas Langerhans cells preferentially induce cellular immunity. Alterations of the DC system result in diseases such as autoimmunity, allergy, and cancer. Conversely, DCs can be exploited for vaccination, and novel vaccines that directly target DCs in vivo are being designed.

Novel autoantibodies against 7SL RNA in patients with polymyositis/dermatomyositis.

OBJECTIVE: Autoantibodies against signal recognition particle (SRP) are detected in patients with polymyositis/dermatomyositis (PM/DM). The SRP consists of 7SL RNA and 6 protein components. We examined autoantibodies against deproteinized 7SL RNA in PM/DM patients with anti-SRP antibodies and evaluated the association of anti-7SL RNA antibodies with PM/DM clinically and serologically. METHODS: Sera from 10 Japanese and 22 North American PM/DM patients with anti-SRP antibodies were tested for the presence of anti-7SL RNA antibodies, using the sera to immunoprecipitate deproteinized RNA extracts derived from HeLa cells. RESULTS: The immunoprecipitation analysis indicated that 5 Japanese (50%) and one North American (5%) patient with anti-SRP antibodies had novel autoantibodies against deproteinized 7SL RNA. The frequency of anti-7SL RNA antibodies was significantly higher in Japanese than North American patients (p = 0.006). The presence of anti-7SL RNA antibodies appeared to be associated with DM (2 patients) and finger swelling (2 PM patients). The seasonal onset of the disease was different (p = 0.008) for Japanese PM/DM patients with anti-7SL RNA antibodies, who developed the disease between October and January (mean month November; p = 0.01) from that of patients without these antibodies, who developed it between June and August (mean month July; p = 0.01). CONCLUSION: Novel autoantibodies against 7SL RNA were identified in patients with PM/DM, and the presence of these antibodies was correlated to ethnic background, clinical features, and season of disease onset. These findings indicated that autoantibodies against 7SL RNA are a novel serological marker for a subset of PM/DM cases.

Rapid induction of peroxisome proliferator-activated receptor gamma expression in human monocytes by monosodium urate monohydrate crystals.

OBJECTIVE: Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a member of the nuclear hormone receptor superfamily and functions as a key regulator of lipid and glucose metabolism, atherosclerosis, and inflammatory responses. This study was undertaken to evaluate the biologic role of PPAR gamma in self-limiting episodes of acute gouty arthritis. To do this, we investigated PPAR gamma expression by monosodium urate monohydrate (MSU) crystal-stimulated monocytes, and we studied the effects of PPAR gamma ligands on crystal-induced acute inflammation. METHODS: PPAR gamma expression by MSU crystal-stimulated human peripheral blood mononuclear cells was determined by reverse transcription-polymerase chain reaction and immunostaining. Expression of CD36 on monocytes was detected by flow cytometric analysis. The effects of PPAR gamma ligands on in vitro crystal-induced cytokine production and on in vivo cellular infiltration during crystal-induced acute inflammation were also investigated. RESULTS: MSU crystals rapidly and selectively induced PPAR gamma expression by monocytes. Gene expression was detected as early as 2 hours, and maximum expression was observed at 4 hours after stimulation. The induced PPAR gamma was functional, since a PPAR gamma ligand was able to up-regulate CD36 expression on monocytes. A natural ligand of PPAR gamma, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15deoxy-PGJ(2)), significantly reduced the crystal-induced production of cytokines by monocytes. Indomethacin inhibited cytokine production only at high concentrations, and an antidiabetic thiazolidinedione (troglitazone) failed to exert significant effects. Administration of troglitazone and 15deoxy-PGJ(2) significantly prevented cellular accumulation in a mouse air-pouch model of MSU crystal-induced acute inflammation. CONCLUSION: Rapid induction of PPAR gamma expression on monocytes by MSU crystals may contribute, at least in part, to the spontaneous resolution of acute attacks of gout.

Production of macrophage inflammatory protein 3alpha (MIP-3alpha) (CCL20) and MIP-3beta (CCL19) by human peripheral blood neutrophils in response to microbial pathogens.

Effects of bacterial pathogens on the production of macrophage inflammatory protein 3alpha (MIP-3alpha) and MIP-3beta from human peripheral blood neutrophils were investigated. Neutrophils produced both chemokines by coincubation with either gram-positive or gram-negative bacteria. Neutrophils may initiate antigen-specific immune responses through the release of these chemokines that are capable of promoting selective recruitment of dendritic cells and T-cell subsets.

Differential expression of leukotriene B4 receptor subtypes (BLT1 and BLT2) in human synovial tissues and synovial fluid leukocytes of patients with rheumatoid arthritis.

OBJECTIVE: To evaluate the role of leukotriene B4 (LTB4) receptors in inflammatory arthritis, we investigated the expression of BLT1 and BLT2 mRNA in synovial tissues of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Methods. BLT1 and BLT2 mRNA were detected by reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization in synovial tissues from 40 patients with RA and 10 patients with OA. Results. BLT2 (the low-affinity receptor for LTB4) showed stronger expression than BLT1 (the high-affinity receptor) in actively inflamed synovial tissue from patients with RA. Synovial macrophages, fibroblast-like cells, and lymphocytes expressed BLT2 mRNA in RA synovial tissues showing active inflammation. BLT2 mRNA was strongly expressed in the synovial lining cells, which also expressed 5-lipoxygenase, an enzyme that synthesizes LTB4. BLT1 and BLT2 mRNA expression in synovial tissues was stronger in RA than in OA by real-time quantitative PCR. In contrast, leukocytes infiltrating synovial fluid predominantly expressed BLT1 mRNA in patients with RA. It was recently reported that these 2 receptors for LTB4 have quite different pharmacological effects and a different tissue distribution. Conclusion. BLT2 is the main receptor mediating the effects of LTB4 in the synovial tissues of patients with RA; this suggests the possibility of developing a new therapy to block LTB4 in inflammatory arthritis.