Vidofludimus inhibits colonic interleukin-17 and improves hapten-induced colitis in rats by a unique dual mode of action.

Vidofludimus (Vido) is a novel oral immunomodulatory drug that inhibits dihydro-orotate dehydrogenase and lymphocyte proliferation in vitro. Vido inhibits interleukin (IL)-17 secretion in vitro independently of effects on lymphocyte proliferation. Our primary goal was to evaluate the in vivo effects of Vido on IL-17 secretion and the parameters of trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. To further delineate the mechanism of action for Vido, rats were dosed concomitantly with uridine (Uri). Young Wistar rats received a 150-µl enema of either phosphate-buffered saline (PBS) or TNBS on study day 1. The ex vivo effects of Vido on 24-h colonic IL-17 secretion were determined by using colonic strips from PBS- or TNBS-treated rats. Some rats were dosed with vehicle, Vido, or Vido + Uri for 6 days. On day 6, the parameters of colitis were determined from colonic tissue. These parameters included macroscopic, histological, and transcription factor measurements, IL-17 production, and numbers of CD3+ T cells. Ex vivo Vido completely blocked IL-23 + IL-1ß-stimulated secretion of IL-17 by colonic strips. In vivo Vido treatment alone most effectively reduced macroscopic and histological pathology and the numbers of CD3+ T cells. In contrast, similarly reduced nuclear signal transducer and activator of transcription 3 (STAT3) binding and IL-17 levels were observed from animals treated with Vido alone and Vido + Uri. Vido improves TNBS-induced colonic inflammation by a unique dual mode of action: 1) inhibiting expansion of colonic T lymphocytes, and 2) suppressing colonic IL-17 production, which is independent from the control of T-lymphocyte proliferation, by inhibition of STAT3 and nuclear factor-κB activation.

4SC-101, a novel small molecule dihydroorotate dehydrogenase inhibitor, suppresses systemic lupus erythematosus in MRL-(Fas)lpr mice.

Immunosuppressive treatments of systemic lupus (SLE) remain associated with significant toxicities; hence, compounds with better toxicity profiles are needed. Dihydroorotate dehydrogenase (DHODH) inhibition with leflunomide has proven to be effective in autoimmune diseases including SLE, but leflunomide can cause a variety of side effects. We hypothesized that 4SC-101, a novel DHODH inhibitor with a more favorable toxicity profile, would be as effective as high-dose cyclophosphamide (CYC) in controlling experimental SLE of female MRL(Fas)lpr mice. Daily oral gavage of 30, 100, and 300 mg/kg 4SC-101 from 12 to 22 weeks of age was compared with either vehicle or CYC treatment (30 mg/kg/week, i.p.) in terms of efficacy and toxicity. Three hundred milligrams per kilogram 4SC-101 was as effective as CYC in depleting spleen autoreactive T cells, B cells, and plasma cells as well as the respective DNA and RNA serum autoantibodies. This was associated with a comparable amelioration of the renal, dermal, and pulmonary SLE manifestations of MRL(Fas)lpr mice. However, even the highest dose of 4SC-101 had no effect on bone marrow neutrophil counts, which were significantly reduced in CYC-treated mice. Together, the novel DHODH inhibitor 4SC-101 is as effective as high dose CYC in controlling SLE without causing myelosuppression. Hence, DHODH inhibition with 4SC-101 might be suitable to treat active SLE with fewer side effects than CYC.

The peptide-semicarbazone S-2209, a representative of a new class of proteasome inhibitors, induces apoptosis and cell growth arrest in multiple myeloma cells.

Bortezomib is the first approved member of a new class of anti-myeloma agents, the proteasome inhibitors. Further proteasome inhibitors are needed to optimise this promising treatment option. S-2209 [1-[1-{1-[(2,4-Dioxo-imidazolidin-1-ylimino)-methyl]-2-phenyl-ethylcarbamoyl}-2-(1H-indol-3-yl)-ethylcarbamoyl]-2-(1H-indol)] inhibits the chymotryptic activity of the human 20S proteasome (half maximal effective concentration, IC(50) approximately 220 nmol/l) which was determined by a proteasome inhibition assay. A nuclear factor kappaB inhibition assay revealed a half maximal effective concentration (EC(50)) of 0.9 micromol/l. The WST-1 growth assay showed inhibition of cell growth of all tested multiple myeloma (MM) cell lines with an IC(50) between 100 nmol/l and 600 nmol/l. Strong induction of apoptosis was seen in MM cells at nanomolar concentrations (IC(50) approximately 300 nm) as well as in primary myeloma cells. No induction of apoptosis was detected in peripheral blood mononuclear cells from healthy humans. Upregulation of p53, activation of JNK protein, and downregulation of Mcl-1 was revealed. Despite the administration of 15 mg S-2209/kg/d in wistar rats, no toxicity with respect to body weight, hepatic enzymes, creatinine or haemoglobin was seen. Proteasome inhibition in white blood cells isolated from the treated rats was higher in the S-2209 treated animals in comparison with the control animals treated with 0.1 mg/kg/d bortezomib. S-2209 is active in myeloma cells and shows a favourable toxicity profile in first in-vivo studies. S-2209 is a promising agent for further clinical development.

Immunosuppression with 4SC-101, a novel inhibitor of dihydroorotate dehydrogenase, in a rat model of renal transplantation.

BACKGROUND: 4SC-101 is a novel dihydroorotate dehydrogenase inhibitor and a blocker of interleukin (IL)-17 secretion with beneficial effects in experimental lupus and inflammatory bowel disease. Its immunomodulatory effect on acute kidney rejection is not known; therefore, in this study, the impact of 4SC-101 was examined in a rat model of acute kidney rejection. METHODS: The kidneys of Brown-Norway rats were orthotopically transplanted into bilaterally nephrectomized Lewis recipients. Allograft recipients were administered with 4SC-101 at dosages of 4, 20, or 60 mg/kg per day, and survival was assessed. In the second setting, the animals were harvested 3 or 5 days after transplantation (Tx), and graft histologic diagnosis was determined. The effects of 4SC-101 on impaired renal function were examined in a model of 5/6 nephrectomy in Lewis rats. RESULTS: The recipients treated with 20-mg/kg 4SC-101 showed prolonged survival compared with placebo-treated animals (mean±SEM, 24±9.3 vs. 5.4±3 days), paralleled by less severe histologic features of acute kidney rejection such as interstitial/perivascular infiltration and tubulitis 3 and 5 days after Tx, and a lower level of IL-17 messenger RNA 5 days after Tx compared with the placebo-treated animals. In the 5/6 nephrectomy model, 20-mg/kg 4SC-101 reduced proteinuria, glomerulosclerosis, and fibrosis with decreased IL-17 messenger RNA expression. CONCLUSIONS: 4SC-101 prolongs survival after Tx, paralleled by amelioration of histologic signs of acute rejection. Furthermore, it showed no worsening effects on kidney function in a remnant kidney model and even slowed the progression of proteinuria and kidney fibrosis. Therefore, 4SC-101 might be a promising pharmaceutical agent in Tx medicine for further investigations.