Effects of diacerein on the quantity and phagocytic activity of thioglycollate-elicited mouse peritoneal macrophages

Diacerhein downregulate proinflammatory cytokines expression and decrease the autoimmune diabetes frequency in nonobese diabetic (NOD) mice

NOD mice are used as experimental models as they develop type 1 diabetes mellitus (DM-1) spontaneously, with a strong similarity to the human disease. Diabetes mellitus type 1 is characterized by the destruction of the islet, orchestrated by T lymphocytes that induce cytokine release like IL-1beta, promoting an inflammatory process. Diacerhein has antiinflammatory properties, inhibiting IL-1. However, the mechanisms involved in immune modulation are not completely understood. In the present study, serum and pancreatic islets were isolated to investigate the relationship between IL-1beta, IFN-gamma, IL-12 and TNF-alpha expression and diabetes onset, morphological aspects, and diacerhein dose dependence in animals treated with different doses (5, 10 and 50 mg/kg/day) and the control group (saline solution). The results demonstrated upregulation of mRNA islets and downregulation of the serum concentration of IL-1beta, IL-12 and TNF-alpha in the group treated with 5 and 10 mg/kg/day diacerhein, when compared with the saline group, and increased IFN-gamma serum concentration in the group treated with 50 mg/kg/day. These results suggest that diacerhein in NOD mice, decreases, in a dose-dependent manner, the diabetes frequency downregulating proinflammatory cytokines, such as IL-1beta, TNF-alpha, IFN-gamma and IL-12 at posttranscriptional or posttranslational level. Furthermore, using the HPLC method, diacerhein and rhein (active metabolite) were detected in serum and pancreas of treated mice.

Rhein inhibits interleukin-1 beta-induced activation of MEK/ERK pathway and DNA binding of NF-kappa B and AP-1 in chondrocytes cultured in hypoxia: a potential mechanism for its disease-modifying effect in osteoarthritis

In the present report, we show that bovine articular chondrocytes cultured in low oxygen tension, i.e. in conditions mimicking their hypoxic in vivo environment, respond to IL-1beta (10 ng/mL) by an increased DNA binding activity of NF-kappaB and AP-1 transcription factors. Incubation of the cells with 10(-5) M rhein for 24 h was found to reduce this activity, particularly in the case of AP-1. Mitogen activated kinases (ERK-1 and ERK-2) were activated by exposure of the chondrocytes to 1-h treatment with IL-1beta. This effect was greater in hypoxia (3% O2) than in normoxia (21% O2). Rhein was capable of reducing the IL-1beta-stimulated ERK1/ERK2 pathway whatever the tension of oxygen present in the environment. The level of c-jun protein, an element of AP-1 complex, was increased by exposure of the chondrocytes to IL-1beta after 2, 6, and 24 h. Addition of rhein at 10(-5) M for 24 h did not reduce the c-jun protein amount. The mRNA steady-state levels of collagen type II (COL2A1) and aggrecan core protein were found to be significantly increased by a 24-h treatment with 10(-5) M rhein. This stimulating effect was also observed in the presence of IL-1beta, suggesting that the drug could prevent or reduce the IL-1beta-induced inhibition of extracellular matrix synthesis. IL-1-induced collagenase (MMPI) expression was significantly decreased by rhein in the same conditions. In conclusion, rhein can effectively inhibit the IL-1-activated MAPK pathway and the binding of NF-kappaB and AP-1 transcription factors, two key factors involved in the expression of several proinflammatory genes by chondrocytes. In addition, the drug can reduce the procatabolic effect of the cytokine, by reducing the MMPI synthesis, and enhance the synthesis of matrix components, such as type II collagen and aggrecan. These results may explain the antiosteoarthritic properties of rhein and its disease-modifying effects on OA cartilage, in spite of absence of inhibition at prostaglandin level.

Effect of diacerein on spontaneous polyarthritis in male New Zealand black/KN mice

OBJECTIVE

Male New Zealand black/KN (NZB/KN) mice spontaneously develop polyarthritis, characterized by destructive damages to the articular cartilage and bone. We assessed effects of diacerein in male NZB/KN mice by radiographic and histopathologic examinations.

DESIGN

Diacerein, cyclosporin A or vehicle for the control were orally administered for 7 months, initiating at 8 weeks of age when the arthritis became apparent.

RESULTS

At 39 weeks of age, the NZB/KN mice developed polyarthritis in the joints of the forelimbs and hind legs, radiographically characterized by joint space narrowing, deformation of the joint surfaces, and bone erosions. Histopathologic findings showed that the tarsal joints and knee sections from the NZB/KN mice exhibited overt arthritic lesion. Radiographic and histopathologic findings showed that diacerein and cyclosporin A at a dose of 30 mg/kg/day significantly reduced the progression of arthritis.

CONCLUSIONS

Diacerein shows articular protecting effects against the development of spontaneous arthritis in male NZB/KN mice and diacerein might be useful in the treatment of chronic inflammatory joint diseases during clinical use.

Diacerein

Rhein, the active metabolite of diacerein, inhibits interleukin-1 activity. Consequently, collagenase production in articular cartilage is reduced. Rhein dose-dependently inhibits superoxide anion production, chemotaxis and phagocytic activity of neutrophils, and macrophage migration and phagocytosis. Articular cartilage damage is reduced by diacerein in animal models of osteoarthritis. Diacerein does not alter renal or platelet cyclooxygenase activity and may therefore be tolerated by patients with prostaglandin-dependent renal function. In clinical trials of < or = 6 months' duration, oral diacerein 50mg twice daily was associated with improvement in 57 to 85% of patients with osteoarthritis. Pain scores and measures of joint function were generally reduced compared with baseline and placebo. Diacerein had similar efficacy to NSAIDs, but a slower onset of action, in comparative trials of < or = 2 months' duration conducted in patients with osteoarthritis. The predominant adverse effects of diacerein are diarrhoea and related disorders.