Differential effects of cyclophosphamide and mycophenolate mofetil on cellular and serological parameters in patients with systemic lupus erythematosus.

INTRODUCTION: Disease activity and therapy show an impact on cellular and serological parameters in patients with systemic lupus erythematosus (SLE). This study was performed to compare the influence of mycophenolate mofetil (MMF) and cyclophosphamide (CYC) therapy on these parameters in patients with flaring, organ-threatening disease. METHODS: SLE patients currently receiving CYC (n = 20), MMF (n = 25) or no immunosuppressive drugs (n = 22) were compared using a cross-sectional design. Median disease activity and daily corticosteroid dose were similar in these treatment groups. Concurrent medication, organ manifestations, and disease activity were recorded, and cellular and serological parameters were determined by routine diagnostic tests or flow cytometric analysis. In addition follow-up data were obtained from different sets of patients (CYC n = 24; MMF n = 23). RESULTS: Although both drugs showed a significant effect on disease activity and circulating B cell subsets, only MMF reduced circulating plasmablasts and plasma cells as well as circulating free light chains within three months of induction therapy. Neither MMF nor CYC were able to reduce circulating memory B cells. MMF lowered IgA levels more markedly than CYC. We did not observe a significant difference in the reduction of IgG levels or anti-dsDNA antibodies comparing patients receiving MMF or CYC. In contrast to MMF, induction therapy with CYC was associated with a significant increase of circulating CD8+ effector T cells and plasmacytoid dendritic cells (PDCs) after three months. CONCLUSIONS: The results indicate differences between MMF and CYC with regard to the mechanism of action. MMF, but not CYC, treatment leads to a fast and enduring reduction of surrogate markers of B cell activation, such as circulating plasmablasts, plasma cells and free light chains but a comparable rate of hypogammaglobulinemia.

Mycophenolic acid counteracts B cell proliferation and plasmablast formation in patients with systemic lupus erythematosus.

INTRODUCTION: Clinical trials revealed a high efficacy of mycophenolate mofetil (MMF)in inducing and maintaining remission in patients with class III-V-lupus nephritis. Also extrarenal manifestations respond to MMF treatment. However, few attempts have been undertaken to delineate its mechanism of action in systemic lupus erythematosus (SLE) a disease characterized by enhanced B cell activation. METHODS: Clinical and paraclinical parameters of 107 patients with SLE were recorded consecutively and analyzed retrospectively. Patients were divided into treatment groups (MMF: n=39, azathioprine (AZA) n=30 and controls without immunosuppressive therapy n=38). To further delineate the effect of mycophenolic acid (MPA) on naive and memory B cells in vitro assays were performed. RESULTS: Although patients taking AZA flared more frequently than patients on MMF or controls, the analysis of clinical parameters did not reveal significant differences.However, profound differences in paraclinical parameters were found. B cell frequencies and numbers were significantly higher in patients taking MMF compared to those on AZA but lower numbers and frequencies of plasmablasts were detected compared to AZA-treated patients or controls. Notably, MMF treatment was associated with a significantly higher frequency and number of transitional B cells as well as naive B cells compared to AZA treatment. Differences in T cell subsets were not significant. MPA abrogated in vitro proliferation of purified B cells completely but had only moderate impact on B cell survival. CONCLUSIONS: The thorough inhibition of B cell activation and plasma cell formation by MMF might explain the favorable outcomes of previous clinical trials in patients with SLE, since enhanced B cell proliferation is a hallmark of this disease.

Relationship between serum levels of macrophage migration inhibitory factor and the activity of antineutrophil cytoplasmic antibody-associated vasculitides.

Macrophage migration inhibitory factor (MIF) is a central proinflammatory cytokine that regulates innate and adaptive immune responses. To evaluate its role in primary vasculitides, we determined MIF by enzyme-linked immunoassay in the sera of patients with Wegener's granulomatosis (WG; n=26), microscopic polyangiitis (MPA; n=10), polyarteritis nodosa (PAN; n=9) and giant cell arteritis (GCA; n=11). Healthy controls (n=26) and patients with sarcoidosis (n=14) were studied in parallel. Serum levels of MIF were significantly higher in patients with WG (median 41.1, range 3.2-120 ng/ml) than those in healthy controls (6.0, 0.015-36.5 ng/ml; P<0.001) and in patients with sarcoidosis (13.8, 0.015-67.1 ng/ml; P<0.05). MIF values were higher in MPA patients (29.5, 9.9-69.4 ng/ml; P<0.01) in comparison with those in healthy controls. In particular, increased levels of MIF were associated with active disease as assessed by the Birmingham Vasculitis Activity Score. Sequential studies showed decreased levels of MIF after initiation of immunosuppressive therapy, with clinical improvement in WG and MPA patients. In contrast, serum levels of MIF were not significantly elevated in patients with PAN and GCA. The results suggest that MIF contributes to the inflammatory process and correlates with disease activity in antineutrophil cytoplasmic antibody-associated vasculitides.

Concomitant reduction of disease activity and IL-10 secreting peripheral blood mononuclear cells during immunoadsorption in patients with active systenic lupus erythematosus.

In patients with systemic lupus erythematosus (SLE) increased secretion of interleukin 10 (IL-10) by peripheral blood mononuclear cells (PBMC) is associated with overproduction of pathogenic autoantibodies. Herein we report the effect of immunoadsorption (IA) on the number of IL-10 secreting PBMC in patients with active SLE. Three courses of IA were performed in 9 patients with active SLE (SLAM 15,9+/-2,9). Each course consisted of 3 treatments on consecutive days. ELISPOT assay using IL-10 specific monoclonal antibodies was used to determine the number of IL- 10 secreting PBMC before and after each treatment. Eleven healthy, age and sex matched volunteers served as controls. Anti-ds-DNA autoantibodies were reduced to 67+/-14% after the treatment period. Before therapy patients showed significantly more spontaneously IL-10 secreting PBMC than controls (p<0.01). After the first course a significant reduction of the IL-10 secreting cells to normal levels was observed which paralleled the development of disease activity (p<0.01). Our results demonstrate a concomitant reduction of disease activity, anti-ds-DNA antibodies and the number of IL-10 secreting PBMC. The production of anti-ds-DNA antibodies and IL-10 are interdependent. Thus we conclude that IA is beneficial in SLE by depletion of these pathogenic antibodies which may lead to a reduced IL-10 secretion in vivo.