Chikako Fukasawa

Increased CD40 Expression on Muscle Cells of Polymyositis and Dermatomyositis: Role of CD40-CD40 Ligand Interaction in IL-6, IL-8, IL-15, and Monocyte Chemoattractant Protein-1 Production

In polymyositis (PM)/dermatomyositis (DM), T cells infiltrate the muscle tissues and interact with muscle cells via cell surface molecules. Recently, myoblasts have been reported to express CD40, but little is known about the role of CD40 in myoblasts. In the present study we examined the expression and involvement of CD40 and CD40 ligand (CD40L) in the interaction between muscle cells and T cells in PM/DM. Immunohistochemical staining revealed that CD40 was expressed on muscle cells in five of five PM and four of five DM patients, and that infiltrating mononuclear cells (MNCs) expressed CD40L in all cases of PM/DM. These CD40L-expressing MNCs were primarily CD4+ T cells. IFN-γ, which is known to induce CD40 expression on various types of cells, was also expressed on the MNCs in four of the PM and four of the DM patients. Although cultured human myoblasts (SkMC 2859) did not express CD40 constitutively, IFN-γ induced CD40 expression in a dose-dependent manner. To clarify the functional roles of CD40-mediated signals, the effects of a trimeric form of recombinant human CD40L on cytokine production were studied in SkMC 2859 that were prestimulated with IFN-γ to express CD40. Recombinant human CD40L markedly increased the production of IL-6, IL-8, IL-15, and monocyte chemoattractant protein-1 of SkMC 2859. The expression of these humoral factors in muscle cells of PM and DM was demonstrated by immunohistochemistry. These results suggest that interaction between T cells and muscle cells via the CD40-CD40L system contributes to the immunopathogenesis of PM/DM by augmenting inflammation via cytokine production by the muscle cells.

Expression and function of inducible co-stimulator in patients with systemic lupus erythematosus: possible involvement in excessive interferon-γ and anti-double-stranded DNA antibody production

Inducible co-stimulator (ICOS) is the third member of the CD28/cytotoxic T-lymphocyte associated antigen-4 family and is involved in the proliferation and activation of T cells. A detailed functional analysis of ICOS on peripheral blood T cells from patients with systemic lupus erythematosus (SLE) has not yet been reported. In the present study we developed a fully human anti-human ICOS mAb (JTA009) with high avidity and investigated the immunopathological roles of ICOS in SLE. JTA009 exhibited higher avidity for ICOS than a previously reported mAb, namely SA12. Using JTA009, ICOS was detected in a substantial proportion of unstimulated peripheral blood T cells from both normal control individuals and patients with SLE. In CD4+CD45RO+ T cells from peripheral blood, the percentage of ICOS+ cells and mean fluorescence intensity with JTA009 were significantly higher in active SLE than in inactive SLE or in normal control individuals. JTA009 co-stimulated peripheral blood T cells in the presence of suboptimal concentrations of anti-CD3 mAb. Median values of [3H]thymidine incorporation were higher in SLE T cells with ICOS co-stimulation than in normal T cells, and the difference between inactive SLE patients and normal control individuals achieved statistical significance. ICOS co-stimulation significantly increased the production of IFN-γ, IL-4 and IL-10 in both SLE and normal T cells. IFN-γ in the culture supernatants of both active and inactive SLE T cells with ICOS co-stimulation was significantly higher than in normal control T cells. Finally, SLE T cells with ICOS co-stimulation selectively and significantly enhanced the production of IgG anti-double-stranded DNA antibodies by autologous B cells. These findings suggest that ICOS is involved in abnormal T cell activation in SLE, and that blockade of the interaction between ICOS and its receptor may have therapeutic value in the treatment of this intractable disease.

Increased CD40 expression in skin fibroblasts from patients with systemic sclerosis (SSc): role of CD40‐CD154 in the phenotype of SSc fibroblasts

Systemic sclerosis (SSc) is a connective tissue disease of unknown etiology that is characterized by tissue fibrosis, which may result from the activation of lesional fibroblasts exhibiting excessive production of extracellular matrix components. However, it has yet to be determined how SSc fibroblasts are activated. CD40 is a cell surface molecule expressed on various cells that is important for the response to activated T cells through CD154. CD40 mRNA was found to be constitutively expressed in both SSc and normal fibroblasts by reverse transcription PCR. Expression of CD40 protein was increased on SSc fibroblasts compared to normal fibroblasts as measured by flow cytometry. Ligation of CD40 by recombinant human CD154 (0.5–2 μg/ml) resulted in increased production of IL‐6, IL‐8, and monocyte chemoattractant protein‐1 in SSc fibroblasts in a dose‐dependent manner, whereas these phenomena were not shown in normal fibroblasts even with the addition of CD154. CD80, a costimulatory molecule, was also induced on SSc fibroblasts by CD40 ligation. In the present study, our findings suggest the possibility of a cell‐mediated response between fibroblasts and T cells in the lesional skin of SSc patients. Since it is suggested that the CD40‐CD154 system may play a crucial role in the aberrant production of immune mediators by SSc fibroblasts, blockage of CD40‐CD154 may be a novel therapeutic strategy for SSc.

Diagnostic reliability of magnetic resonance imaging for central nervous system syndromes in systemic lupus erythematosus: a prospective cohort study

BackgroundPrevious studies of magnetic resonance imaging (MRI) as a diagnostic tool for central nervous system (CNS) syndromes in systemic lupus erythematosus (SLE) contained several limitations such as study design, number of enrolled patients, and definition of CNS syndromes. We overcame these problems and statistically evaluated the diagnostic values of abnormal MRI signals and their chronological changes in CNS syndromes of SLE.MethodsWe prospectively studied 191 patients with SLE, comparing those with (n = 57) and without (n = 134) CNS syndrome. CNS syndromes were characterized using the American College of Rheumatology case definitions.ResultsAny abnormal MRI signals were more frequently observed in subjects in the CNS group (n = 25) than in the non-CNS group (n = 32) [relative risk (RR), 1.7; 95% confidence interval (CI), 1.1-2.7; p = 0.016] and the positive and negative predictive values for the diagnosis of CNS syndrome were 42% and 76%, respectively. Large abnormal MRI signals (ø ≥ 10 mm) were seen only in the CNS group (n = 7; RR, 3.7; CI, 2.9-4.7; p = 0.0002), whereas small abnormal MRI signals (ø < 10 mm) were seen in both groups with no statistical difference. Large signals always paralleled clinical outcome (p = 0.029), whereas small signals did not (p = 1.000).ConclusionsAbnormal MRI signals, which showed statistical associations with CNS syndrome, had insufficient diagnostic values. A large MRI signal was, however, useful as a diagnostic and surrogate marker for CNS syndrome of SLE, although it was less common.

The Bcl-2/Bax ratio of lymphocytes from human systemic lupus erythematosus patients

Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease. It has recently been suggested that a failure of apoptosis wherein autoreactive lymphocytes continue to survive is a major factor in the pathogenesis of SLE. Fas antigen is increased on peripheral blood lymphocytes from human SLE patients while Bcl-2 protein, which inhibits apoptosis, is highly expressed in peripheral T lymphocytes of SLE patients. The Bcl-2 family includes homologs that are believed to be related to regulation of apoptosis. Of these, Bax is capable of forming heterodimers with Bcl-2, thereby counteracting the action of Bcl-2. The present study examines the ratio of Bcl-2 to Bax in relation to the activity of SLE, with implications relating to the survival or death of lymphocytes. The ratio of Bcl-2 to Bax in active SLE was significantly higher than in inactive SLE and in normal controls. Although the exact role of apoptosis in SLE is still unclear, a high ratio of Bcl-2 to Bax in active SLE patients might support the survival of autoreactive cells.

Dipyridamole stress thallium perfusion scan for evaluating myocardial involvement in systemic sclerosis

Abstract To evaluate the usefulness of a dipyridamole stress thallium-201 (Tl-201) perfusion scan in detecting myocardial involvement in systemic sclerosis we performed Tl-201 scans, electrocardiograms (ECG), and echocardiograms (UCG) on 24 patients with systemic sclerosis (11 diffuse type, 13 limited type) sequentially selected randomly over an 8-month period, and compared the findings. Cardiac catheterization, coronary angiography (CAG), and right ventricular endomyocardial biopsy were performed as necessary. Of the 24 patients, Tl-201 scans revealed fixed defects (FDs; myocardial fibrosis) and/or reversible defects (RDs; myocardial ischemia) in nine patients, whereas ECG and UCG revealed defects in four and three patients, respectively. Biopsy specimens obtained from the three patients with FDs also showed both ECG and UCG abnormalities indicative of myocardial fibrosis despite their normal appearance with CAG. Autopsy findings on the heart of a patient who died of acute heart failure showed myocardial fibrosis predominantly in the left anteroposterior wall. This was consistent with the FDs area detected using the Tl-201 perfusion scan. In a patient with chronic heart failure, left ventriculography showed a decrease in the anterior wall motion of the left ventricle which coincided with the FDs area in the Tl-201 perfusion scan. In conclusion, dipyridamole stress Tl-201 scanning is useful for evaluating myocardial involvement in systemic sclerosis.