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Biomedical subjects

R Zitnik

Publications and source records attributed to R Zitnik.

4 recordsLinked to original sources

A global phase III randomized controlled trial of etanercept in psoriasis: safety, efficacy, and effect of dose reduction.

BACKGROUND: In previous studies, etanercept significantly improved plaque psoriasis and was well tolerated. OBJECTIVES: To examine further the efficacy and safety of etanercept and to assess maintenance of treatment effect after dose reduction of etanercept. METHODS: In this multicentre 24-week study in the U.S.A., Canada and Western Europe, patients were at least 18 years old; had active, clinically stable plaque psoriasis involving at least 10% of body surface area; had a minimum Psoriasis Area and Severity Index (PASI) of 10 at screening; and had received or were a candidate to receive systemic psoriasis therapy or phototherapy. During the first 12 weeks of the study, patients were randomly assigned to receive by subcutaneous injection etanercept twice weekly (BIW) at a dose of 50 mg or 25 mg, or placebo BIW in a double-blind fashion. During the second 12 weeks, all patients received etanercept 25 mg BIW. The primary endpoint was a 75% or greater improvement from baseline in PASI (PASI 75) at 12 weeks. RESULTS: Five hundred and eighty-three subjects were randomized and received at least one dose of study drug. At week 12, a PASI 75 was achieved by 49% of patients in the etanercept 50 mg BIW group, 34% in the 25 mg BIW group, and 3% in the placebo group (P < 0.0001 for each etanercept group compared with placebo). At week 24 (after 12 weeks of open-label 25 mg etanercept BIW), a PASI 75 was achieved by 54% of patients whose dose was reduced from 50 mg BIW to 25 mg BIW, by 45% of patients in the continuous 25 mg BIW group, and by 28% in the group that received placebo followed by etanercept 25 mg BIW. Etanercept was well tolerated throughout the study. CONCLUSIONS: Etanercept provided clinically meaningful benefit to patients with chronic plaque psoriasis, with no apparent decrease in efficacy after dose reduction.

Adolescent↗

Scatter factor modulates the metastatic phenotype of the EMT6 mouse mammary tumor.

EMT6 is a transplantable mouse mammary tumor cell line that has been utilized widely as a model system to study the effects of various treatments on local tumor growth and pulmonary metastasis. In this study, we examined the cellular mechanisms by which scatter factor (SF), a fibroblast-derived cytokine that stimulates epithelial cell motility, may contribute to tumor-cell dissemination, using the EMT6 model system. In vitro, SF stimulated EMT6 cell motility, invasiveness and cell-surface expression of urokinase (an enzyme required for cell migration through tissue). SF differentially stimulated EMT6 cell adhesion to and migration onto surfaces coated with collagen I and laminin. EMT6 cells treated in vitro with SF and injected i.v. into isogeneic BALB/c-Rw mice showed a small but significant increase (1.7-fold) in lung colony formation as compared with control cells. For EMT6 cells in vitro, SF had no effect on DNA synthesis, cell proliferation, cell size distribution, or in vitro colony-forming ability. Thus, the increase in lung colonization may be due to enhanced ability of SF-treated cells to adhere to subendothelial basement membrane or to invade through tissue. Studies of the tissue distribution of SF in BALB/c-Rw mice demonstrated high levels of active factor in the lung. Thus, the presence of endogenous pulmonary SF may have reduced the degree to which SF treatment stimulated EMT6 lung colonization. Significant SF activity was also found in extracts of EMT6 tumors. Cultured EMT6 cells did not produce SF, but did produce high titers of a soluble low-molecular-weight protein activity that is capable of stimulating SF production in human fibroblasts 3- to 5-fold. EMT6 tumor extracts contained high titers of a similar SF-inducing activity. These observations suggest that SF may contribute to the invasive and metastatic phenotype of EMT6 cells via a paracrine mechanism in which tumor cells induce the production of SF in stromal fibroblasts.

Animals↗

IL-1 and transforming growth factor-beta regulation of fibroblast-derived IL-11.

IL-11 and IL-6 are fibroblast-derived cytokines with overlapping biologic properties. To determine whether IL-11 and IL-6 are similarly regulated, we characterized the effects of rIL-1 and TGF-beta (beta 1 and beta 2) on human lung fibroblast IL-11 production and compared this regulation with that of IL-6. Unstimulated fibroblasts did not produce significant amounts of IL-11, whereas rIL-1 alpha and TGF-beta were dose-dependent stimulators of IL-11 protein production, mRNA accumulation, and gene transcription. rIL-1 alpha and TGF-beta also interacted in a synergistic fashion to further increase IL-11 protein production and mRNA accumulation. The effects of rIL-1 and TGF-beta individually were not altered by the cyclic nucleotide-dependent protein kinase inhibitor HA1004, protein kinase C (PKC) inhibition with staurosporine, or chronic phorbol ester preincubation, or the calmodulin antagonists W7 and TFP. The effects of rIL-1 alpha and TGF-beta in combination were also unaltered by HA1004, staurosporine, and chronic phorbol ester exposure. A23187, however, did induce IL-11 mRNA accumulation and W7 and TFP did reverse the synergistic stimulation caused by rIL-1 and TGF-beta in combination. In contrast with the regulation of IL-11, TGF-beta did not effectively stimulate IL-6 mRNA accumulation, rIL-1 alpha was a more potent stimulator of IL-6 than IL-11 production, and rIL-1-induced IL-6 mRNA accumulation was augmented by W7 and TFP. These studies demonstrate that: 1) rIL-1, TGF-beta, and agents that increase intracellular calcium stimulate lung fibroblast IL-11; 2) the IL-11 stimulatory effects of rIL-1 and TGF-beta are, at least partially, transcriptionally mediated and are the result of signal transduction pathways that are largely PKC, cyclic nucleotide, and calmodulin independent; and 3) rIL-1 and TGF-beta interact in a synergistic fashion to further increase fibroblast IL-11 production and that this synergy is mediated by a largely PKC- and cyclic nucleotide-independent and calmodulin-dependent activation pathway. Importantly, they also demonstrate that rIL-1 and TGF-beta stimulate lung fibroblast IL-6 and IL-11 production via distinct and differentially regulatable activation pathways.

Calcimycin↗