APC0576, a novel inhibitor of NF-kappaB-dependent gene activation, prevents pro-inflammatory cytokine-induced chemokine production in human endothelial cells

APC0576 decreases production of pro-inflammatory chemokine and extracellular matrix by human Tenon's capsule fibroblasts

PURPOSE

To control intraocular pressure in patients treated by trabeculectomy, progressive inflammation, fibroblast proliferation, and the enhanced expression of extracellular matrix (ECM), causes of scar formation at the bleb, must be prevented. Using human Tenon's capsule fibroblasts (TCFs), we examined the effect of APC0576, a suppressor of NF-kappaB-dependent gene activation of human vascular endothelial cells that does not adversely affect cell viability, on the production of pro-inflammatory chemokine and ECM. Its effect on TCF proliferation was also assessed.

METHODS

Enzyme-linked immunosorbent assay was used to detect the pro-inflammatory cytokines IL-8 and MCP-1 in the supernatant of TCFs stimulated with IL-1alpha in the presence or absence of APCO576 and ECM proteins, COOH-terminal peptide of type I procollagen (PIP), fibronectin (FN), and laminin (LN) in supernatants and lysates of TCFs stimulated with IL-1alpha or TGF-beta. The proliferative response of IL-1alpha-stimulated TCFs was examined using the SF formazan solution reaction.

RESULTS

APC0576 significantly suppressed the production by TCFs of IL-8 (p<0.0001), MCP-1(p<0.0001), PIP (supernatants: p<0.0001, cell lysates: p<0.0001), LN (supernatants: p<0.0001, lysates: p<0.0001), and FN (supernatants: p<0.0001, lysates: p<0.0001) as well as their proliferation (p<0.0001).

CONCLUSIONS

APC0576 suppressed pro-inflammatory chemokine and ECM production in TCFs as well as their proliferation. It may represent a novel candidate for the postoperative management of patients treated by trabeculectomy.

Tyrphostin AG 126 inhibits development of postoperative ileus induced by surgical manipulation of murine colon

Manipulation of the bowel during abdominal surgery leads to a period of ileus, which is most severely manifested after procedures that directly involve the colon. Ileus is associated with the increased expression of proinflammatory cytokines and chemokines, a leukocytic infiltration into the muscularis, and the release of mediators from resident and infiltrating leukocytes that directly inhibit intestinal smooth muscle contractility. Phosphorylation of tyrosine residues on regulatory proteins by protein tyrosine kinases (PTKs) occurs at multiple steps in the signaling cascades that regulate the expression of proinflammatory genes. The purpose of this study was to determine whether inhibition of PTK activity will attenuate the inflammatory response associated with colonic ileus and lead to improved function. Using a rodent model of colonic postoperative ileus, we demonstrate that a single bolus injection of the PTK inhibitor tyrphostin AG 126 (15 mg/kg sc) before surgery significantly attenuates the surgically induced impairment of colonic contractility both in vivo and in vitro. Improvement in function was associated with a reduction in magnitude of inflammatory cell infiltrate and with a decrease in transcription of genes encoding proinflammatory mediators IL-1beta and monocyte chemoattractant protein (MCP)-1, inducible nitric oxide synthase, and cyclooxygenase-2. Furthermore, tyrphostin AG 126 pretreatment significantly inhibited activation of multifactorial transcription factor NF-kappaB, which could form the basis for reduction in proinflammatory mediator expression. These data demonstrate for the first time that inhibition of PTK activity may represent a novel approach for management of ileus in the clinical setting.

APC0576: a novel small molecule, immunosuppressive agent effective in primate models

BACKGROUND

APC0576, 5-(((S)-2,2-dimethylcyclopropanecarbonyl)amino)-2-(4-(((S)-2,2-dimethylcyclopropanecarbonyl)amino)phenoxy)pyridine is a novel synthetic compound with an inhibitory activity on NF-kappaB-dependent gene activation and chemokine synthesis in human endothelial cells. This article describes the effect of APC0576 on T-cell-dependent immune functions in vitro and in vivo in primate models, because NF-kappaB is known to be one of the potent mediators in T-cell activation.

METHODS

The effects of APC0576 on interleukin-2 production and proliferative responses in human peripheral blood mononuclear cells were studied under various stimuli with in vitro culture assay. Next, female rhesus monkeys were immunized with tetanus toxoid (TTx), and APC0576 was orally administered for 4 weeks. Serum-specific antibody for TTx was monitored weekly using an enzyme-linked immunosorbent assay, and delayed-type hypersensitivity reaction was examined after 4 weeks of APC0576 treatment. To evaluate the immunosuppressive activity, APC0576 was orally administered for 32 days to rhesus monkeys that received transplants of allogeneic kidney.

RESULTS

APC0576 effectively suppressed interleukin-2 production and proliferation in activated human peripheral blood mononuclear cells. Both delayed-type hypersensitivity reaction and specific antibody formation evoked by TTx was significantly and dose-dependently attenuated by 4 weeks treatment of APC0576 without any serious toxicologic signs. Allogeneic kidneys grafted in rhesus monkeys were not rejected and fully functioned during the 32 days of APC0576 treatment, although they were rapidly rejected after the withdrawal of the drug.

CONCLUSIONS

A novel, orally available immunosuppressive agent, APC0576, effectively inhibited T-cell-based immune responses both in vitro and in vivo. APC0576 may have potential for a therapeutic agent in clinical organ transplantation and various cytokine-mediated diseases.

p47phox participates in activation of RelA in endothelial cells

Activation of endothelial cell NF-kappaB by interleukin (IL)-1 constitutes an event critical to the progression of the innate immune response. In this context, oxidants have been associated with NF-kappaB activation, although the molecular source and mechanism of targeting have remained obscure. We found that RelA, essential for NF-kappaB activation by IL-1, was associated with the NADPH oxidase adapter protein p47(phox) in yeast two-hybrid, coprecipitation, and in vitro binding studies. RelA and p47-GFP also colocalized in endothelial cells in focal submembranous dorsoventral protrusions. Overexpression of p47(phox) synergized with IL-1beta in the activation of an artificial kappaB-luciferase reporter and specifically augmented IL-1beta-induced RelA transactivation activity. p47(phox) overexpression also greatly increased IL-1beta-stimulated RelA phosphorylation, whereas it had no effect on I-kappaB degradation or on RelA nuclear translocation or kappaB binding. The tandem SH3 domains of p47(phox) were found to associate with a proline-rich mid-region of RelA (RelA-PR) located between the Rel homology and transactivation domains. The RelA-PR peptide blocked interaction of p47(phox) and RelA, and ectopic expression of RelA-PR abrogated IL-1beta-induced transactivation of the NF-kappaB-dependent E-selectin promoter. Further, suppression of NADPH oxidase function through the inhibitor diphenylene iodonium, the superoxide dismutase mimetic Mn(III) tetrakis(4-benzoic acid)porphyrin (MnTBAP), or expression of a dominant interfering mutant of a separate NADPH oxidase subunit (p67(V204A)) decreased IL-1beta-induced E-selectin promoter activation, suggesting that p47(phox) facilitates NF-kappaB activation through linkage with the NADPH oxidase. IL-1beta rapidly increased tyrosine phosphorylation of IL-1 type I receptor-associated proteins, suggesting that oxidants may operate through inactivation of local protein-tyrosine phosphatases in the proximal IL-1beta signaling pathway leading to RelA activation.