Kazuko Shiozawa

Role of the MICA Polymorphism in Systemic Lupus Erythematosus

OBJECTIVE To study the genetic contribution of major histocompatibility complex class I polypeptide-related sequence A (MICA), important in natural killer (NK) cell function, in patients with systemic lupus erythematosus (SLE). METHODS Japanese patients with SLE (n=716), those with rheumatoid arthritis (RA) (n=327), and healthy control subjects (n=351) were genotyped for the Val129 Met polymorphism (rs1051792) and transmembrane (TM) alanine-encoding GCT repeats, termed A4, A5, A5.1, A6, and A9, in the MICA gene. Recombinant human MICA-GST fusion proteins were tested on the NK cell line NK92MI for the expression of NK group 2, member D (NKG2-D), NK cell-mediated cytotoxicity, and interferon-γ (IFNγ) production. RESULTS The MICA 129Met allele, TMA9 allele, and 129Met/Met genotype were positively associated with SLE (corrected P [Pcorr]=0.01 and odds ratio [OR] 1.3, Pcorr=0.003 and OR 1.6, and Pcorr=0.02 and OR 1.8, respectively), while the MICA 129Val allele was negatively associated with SLE (Pcorr=0.01, OR 0.8). The MICA 129Met;A9 haplotype was also associated with SLE (Pcorr=0.0006, OR 1.8), and there was an additive genetic effect between the MICA 129Met;A9 haplotype and HLA-DRB1*15:01. When NK92MI cells were incubated in vitro with recombinant human disease-associated 129Met;A9 (the combination of polymorphisms at 129Met and TMA9), expression of NKG2-D on NK92MI cells and cytotoxicity of the NK cells were inhibited, but production of IFNγ from NK92MI cells was enhanced. CONCLUSION The MICA polymorphism is genetically associated with SLE, and MICA appears to contribute to the pathogenesis of SLE by modulating NK cell function.

Death receptor 3 ( DR3 ) gene duplication in a chromosome region 1p36.3: gene duplication is more prevalent in rheumatoid arthritis

The death receptor 3 (DR3) gene is a member of the apoptosis-inducing Fas gene family. In the current study, fluorescence in situ hybridization (FISH) and Fiber-FISH revealed the existence of a second DR3 gene ∼200 kb upstream of the original DR3 gene. The existence of the duplicated DR3 gene was confirmed by sequencing the corresponding human artificial chromosome clones as well as with quantitative PCR that measured the ratio of the DR3 gene mutation (Rm), intrinsic to rheumatoid arthritis (RA) patients, by simultaneous amplification of the normal and mutated DR3 sequences. The DR3 gene duplication measured by FISH was found to be more frequent in patients with RA as compared to healthy individuals. We therefore surmise that the human DR3 gene can be duplicated and that this gene duplication is more prevalent in patients with RA.

Pathogenic importance of fibronectin in the superficial region of articular cartilage as a local factor for the induction of pannus extension on rheumatoid articular cartilage.

To identify the local factors in cartilage that are responsible for the induction of pannus invasion, a 14 day organ culture study in which rheumatoid synovium was grown in contact with cartilage pieces was carried out. Rheumatoid synovium preferentially extended over hyaluronidase treated cartilage pieces, but detached from untreated pieces. Rheumatoid synovium extended over hyaluronidase treated cartilage surfaces containing fibronectin more extensively than over surfaces treated with hyaluronidase only. Extension over hyaluronidase treated cartilage surfaces containing immune complexes was small. The adherence of synovial cells to hyaluronidase treated cartilage slices in vitro was specifically inhibited by the synthetic peptide, Gly-Arg-Gly-Asp-Ser-Pro, which is the adhesive portion of the fibronectin molecule. Furthermore, synovial fibroblast-like cellular extension, morphologically similar to rheumatoid pannus, was observed in the organ culture experiments in which rheumatoid synovium grew over hyaluronidase treated cartilage surfaces containing fibronectin. Synovial tissue extension over fibronectin coated surfaces was inhibited when hyaluronic acid and chondroitin-4-sulphate, major components of cartilage proteoglycans, were present on the cartilage surface. These findings suggest that fibronectin present in the superficial region of cartilage potentiates rheumatoid synovial extension and proteoglycans and immune complexes inhibit rheumatoid synovial extension. It is likely that fibronectin deposited on the eroded surface of articular cartilage induces pannus formation in rheumatoid arthritis.

Clinical studies of renal disease in Sjögren's syndrome.

When 17 patients with Sjögrens syndrome, without apparent clinical manifestations of renal disease, were examined renal function studies frequently indicated abnormalities in their renal phosphate handling. The percentage tubular reabsorption of phosphate (%TRP) was decreased in six (35.3%), and maximal tubular reabsorption rate for phosphate (TmPO4/GFR) was low in eight (47.1%). In contrast, indices of renal calcium handling and serum parathyroid hormone levels were normal, suggesting that the abnormalities of phosphate metabolism were due not to extrinsic, but rather to intrinsic disease processes occurring in the kidney in Sjögrens syndrome. When the patients were divided into two groups according to the presence or absence of a renal tubular acidification defect (RTAD), patients with RTAD were younger (p less than 0.005), had longer disease duration (p less than 0.01), lower creatinine clearance (p less than 0.05), and higher incidence of low %TRP (p less than 0.05). Thus the patients with lower creatinine clearance generally had disease of longer duration at diagnosis and tended also to have defects in concentrating and acidifying the urine.

Human wee1 kinase is directly transactivated by and increased in association with c-Fos/AP-1: rheumatoid synovial cells overexpressing these genes go into aberrant mitosis.

Wee1 kinase downregulates the M-phase promoting factor, a complex of cdc2 and cyclin B kinase, that controls mitotic cell division. We isolated human wee1 kinase gene promoter and found that it contained one AP-1-binding motif in its promoter region (5′-CGAGTCA-3′; −823/−817), through which wee1 kinase gene was directly transactivated by c-Fos/AP-1. In rheumatoid synovial cells, wee1 kinase was increased in conjunction with the increase of c-Fos/AP-1 and the substrate of wee1, cdc2, was phosphorylated. The amount of wee1 and c-Fos and the phosphorylation of cdc2 were decreased after treatment of the cells with an inhibitor of AP-1, curcumin. A significant proportion of cultured synovial cells of the patients with rheumatoid arthritis, but not those of osteoarthritis, shifted to a tetraploid (4C) state upon long-term culture. Thus, human wee1 kinase gene is directly transactivated by and increased in association with c-Fos/AP-1, and rheumatoid synovial cells overexpressing these genes go into aberrant mitosis.

Human epidermal growth factor for the stratification of synovial lining layer and neovascularisation in rheumatoid arthritis.

Immunohistochemical study showed selective localisation of human epidermal growth factor (hEGF) to the synovial lining layer. Although the synovial lining layer of the rheumatoid, osteoarthritic, and traumatic joints was hEGF positive, hEGF staining was especially dense at the rheumatoid synovial lining layer; the staining increasing linearly according to the degree of stratification of the lining layer (r = 1). Human epidermal growth factor was ultrastructurally localised to cytoplasm, especially to rough endoplasmic reticulum, of the synovial lining fibroblast-like (type B) cell. Only the cell surface of macrophage-like (type A) cells was hEGF positive. When different histological variables were compared with each other a positive correlation was found between hEGF staining of the synovial lining layer and the degree of neovascularisation of rheumatoid synovium (r = 0.72). Although some lymphocytes were weakly hEGF positive, neovascularisation did not correlate with the extent of lymphocyte infiltration or of hEGF staining of lymphocytes. Lymphocyte infiltration or hEGF staining of lymphocytes did not correlate with hEGF staining of the synovial lining layer, whereas the lymphocyte infiltration correlated positively with the extent of perivascular accumulation of lymphocytes (r = 0.89). These findings suggest that (a) hEGF is synthesised by and secreted through endoplasmic reticulum and Golgi apparatus from the synovial lining type B cell; (b) hEGF is at least partially responsible for the pathogenesis of stratification of the rheumatoid synovial lining layer, and perhaps of neovascularisation of the rheumatoid synovium, whereas it is not responsible for lymphocyte accumulation to the rheumatoid synovium.

Heat shock protein 90 maintains the tumour-like character of rheumatoid synovial cells by stabilizing integrin-linked kinase, extracellular signal-regulated kinase and protein kinase B

OBJECTIVE To clarify the contribution of heat shock protein 90 (HSP90) to the pathogenesis of RA, we studied the effects of geldanamycin (GA), an inhibitor of HSP90, on excessive cellular extension and resistance to apoptosis induction of rheumatoid synovial cells. METHODS Expression of integrin-α5β1 and integrin-linked kinase (ILK) in synovial cells was determined by western blot. The peripheral localization of ILK, reorganization of F-actin, complex formation of ILK with particularly interesting new cysteine-histidine protein (PINCH) and α-parvin, and activation of Rac/cdc42 in synovial cells were examined by using immunohistochemistry and immunoprecipitation. Apoptosis induction by GA treatment was analysed by nuclear staining, cell proliferation assay and western blot of caspase. Effects of GA on mitogen-activated protein kinase (MAPK), PI-3K/protein kinase B (Akt) pathway, mitochondrial Bcl-2 pathway and activation of nuclear factor-κB (NF-κB) were examined by western blot and ELISA. RESULTS HSP90 was overexpressed in synovial cells while GA decreased the expression of integrin-α5β1 and ILK. The peripheral localization of ILK, reorganization of F-actin, complex formation of ILK with PINCH and α-parvin, and activation of Rac/cdc42 in synovial cells were all inhibited by GA treatment. We found that HSP90 stabilized and regulated the MAPK and PI-3K/Akt pathway, thereby inhibiting HSP90-potentiated synovial apoptosis by stimulating caspases and the mitochondrial Bcl-2 pathway on the one hand and inhibiting the activation of NF-κB on the other. CONCLUSION The contribution of HSP90 is important in the pathogenesis of RA that potentiates a tumour-like synovial overgrowth by stabilizing ILK, extracellular signal-regulated kinase and Akt.

A Review of the Histopathological Evidence on the Pathogenesis of Cartilage Destruction in - Rheumatoid Arthritis

These are three ways of cartilage destruction as summarized in Fig. 1. The relative significance of the contribution among them to the pathogenesis of cartilage destruction varies individually. It appears important here to note that chondrocytes themselves are not actively involved in the pannus formation. Chondrocytes only provide a basis for extension of the pannus by proteolytic digestion of cartilage matrix. It is however possible in some individuals that the digestion of cartilage by chondrocytes plays the predominant role in their cartilage destruction. Besides the autonomous proliferative potential of pannus tissue, it seems evident that active synovitis is the main cause of cartilage loss. This is quite important from the therapeutic view point, because we can expect to halt the disease process causing joint deformities by controlling the active synovitis.

Efficacy and safety of olokizumab in Asian patients with moderate-to-severe rheumatoid arthritis, previously exposed to anti-TNF therapy: Results from a randomized phase II trial.

Abstract Objectives: This phase II, dose-ranging, double-blind, placebo-controlled, randomized study (NCT01463059) evaluated efficacy and safety of olokizumab (OKZ), a humanized anti-interleukin 6 monoclonal antibody, in Asian patients with moderately-to-severely active rheumatoid arthritis (RA) who had previously failed anti-TNF therapy. Methods: Patients were randomized to one of six treatment arms: placebo or OKZ (60 mg/120 mg/240 mg every four weeks [Q4W]; or 60 mg/120 mg every two weeks [Q2W]); stratified by country and number of prior anti-TNFs. Primary efficacy variable was Week 12 change from baseline (CFB) in DAS28 CRP for 4-week cumulative dose groups of OKZ and placebo; secondary efficacy variables were Week 12 ACR20/ACR50/ACR70 response rates. Patients continued MTX treatment from baseline, without additional csDMARDs. Results: Of 119 randomized patients, 88.2% completed the study. Greater improvements in DAS28(CRP) mean CFB at Week 12 were observed in all OKZ 4-week cumulative dose groups (60 mg/120 mg/240 mg) versus placebo (p < 0.0001). Week 12 ACR20/ACR50 response rates were higher in all OKZ cumulative dose groups versus PBO (p < 0.05). Incidences of adverse events were similar across OKZ 4-week cumulative dose groups (76.9–84.4%) and placebo (82.8%) with no deaths. Conclusions: OKZ demonstrated improvements in efficacy variables versus placebo in Asian patients with moderately-to-severely active RA who had previously failed anti-TNF therapy. The safety profile was as expected for this class of drug.

Anticitrullinated Protein Antibody, But Not Its Titer, Is a Predictor of Radiographic Progression and Disease Activity in Rheumatoid Arthritis

Objective. To study the contribution of anticitrullinated protein antibody (ACPA), and especially of its titer, to radiographic progression and disease activity in rheumatoid arthritis (RA). Methods. Patients with RA (n = 396) who attended a Japanese clinic within 2 years after disease onset were divided into the following groups according to second-generation (ACPA-2) ACPA titer on their first visit: negative (0–4.4 U/ml; n = 115), low-positive (4.5–121 U/ml; n = 141), and high-positive (> 121 U/ml; n = 140). The ACPA-2-positive groups were further subdivided into lowest (4.5–32 U/ml), low (33–121 U/ml), high (122–277 U/ml), and highest (> 278 U/ml) quartiles. All patients were treated with disease-modifying antirheumatic drugs (DMARD) including methotrexate, but not biologics. Subsequent radiographic progression and disease activity for 2 years were prospectively evaluated using the van der Heijde-modified Sharp score (SHS) and 28-joint Disease Activity Score (DAS28). Results. After treatment with DMARD, the disease activity (including number of swollen joints, number of tender joints, duration of morning stiffness, DAS28-erythrocyte sedimentation rate, and DAS28-C-reactive protein) was significantly decreased in all patient groups. Disease activity and radiographic progression as revealed by the change in SHS remained relatively higher in the ACPA-2 low- and high-positive groups as compared with the ACPA-2-negative group. The relationship between the titer of ACPA-2 at baseline and subsequent radiographic progression was not exactly linear, and the extent of disease activity or radiographic progression was similar between ACPA-2 low- and high-positive groups and also between ACPA-2 lowest- and highest-positive quartile groups. The results were demonstrable in cumulative SHS probability plots, and also repeatable in seronegative patients, which indicated that the titer of ACPA-2 is not a predictor of disease activity or radiographic progression in RA, and ACPA-2-negative patients, especially those with < 3 U/ml, showed minimal radiographic progression. Conclusion. Presence of ACPA-2, but not its titer, at baseline is a predictor of radiographic progression or disease activity, where radiographic progression is minimal in ACPA-2-negative patients.