A Novel Carboline Derivative Inhibits Nitric Oxide Formation in Macrophages Independent of Effects on Tumor Necrosis Factorαand Interleukin-1βExpression

Abstract

Neuropathic pain is a maladaptive immune response to peripheral nerve injury that causes a chronic painful condition refractory to most analgesics. Nitric oxide (NO), which is produced by nitric oxide synthases (NOSs), has been implicated as a key factor in the pathogenesis of neuropathic pain. b-Carbolines are a large group of natural and synthetic indole alkaloids, some of which block activation of nuclear factor k-light-chain-enhancer of activated B cells (NF-kB), a predominant transcriptional regulator of NOS expression. Here, we characterize the inhibitory effects of a novel 6-chloro-8-(glycinyl)-amino-b-carboline (8-Gly carb) on NO formation and NF-kB activation in macrophages. 8-Gly carb was significantly more potent than the NOS inhibitor NG-nitro-Larginine methyl ester in inhibiting constitutive and inducible NO formation in primary rat macrophages. 8-Gly carb interfered with NF-kB-mediated gene expression in differentiated THP1-XBlue cells, a human NF-kB reporter macrophage cell line, but only at concentrations severalfold higher than needed to significantly inhibit NO production. 8-Gly carb also had no effect on tumor necrosis factor a (TNFa)-induced phosphorylation of the p38 mitogenactivated protein kinase in differentiated THP1 cells, and did not inhibit lipopolysaccharide-or TNFa-stimulated expression of TNFa and interleukin-1b. These data demonstrate that relative to other carbolines and pharmacologic inhibitors of NOS, 8-Gly carb exhibits a unique pharmacological profile by inhibiting constitutive and inducible NO formation independent of NF-kB activation and cytokine expression. Thus, this novel carboline derivative holds promise as a parent compound, leading to therapeutic agents that prevent the development of neuropathic pain mediated by macrophage-derived NO without interfering with cytokine expression required for neural recovery following peripheral nerve injury.

Investigation of Inactive-State κ Opioid Receptor Homodimerization via Single-Molecule Microscopy Using New Antagonistic Fluorescent Probes

“…An alternative synthetic pathway was trialed for the tetraglycine compounds by reacting intermediate 7 with N -Cbz-tetraglycine. Due to the poor solubility of the latter, the EDCI/HOBt coupling reaction was applied in dimethyl formamide (DMF) medium as well as in pyridine medium . The combination of lower yields, partial Fmoc deprotection due to the presence of pyridine, and hardship on the following Cbz deprotection rendered the latter synthetic route unfavorable though.…”

Baicalin improves the survival in endotoxic mice and inhibits the inflammatory responses in LPS-treated RAW 264.7 macrophages

“…35 Interestingly, TNF-α binding to TNF receptor can further induce NF-kB-p65 nuclear translocation, suggesting that there is a positive loop between TNF-α and NF-κB activation. 10 Treatment with baicalin was found to significantly inhibit NF-κB nuclear translocation in LPSstimulated macrophages. Considering the importance of NF-κB on inflammation and in the development of sepsis, the inhibitory effects of baicalin on these genes associated with inflammation may be at least in part mediated by suppressing NF-κB activation.…”

“…In response to LPS, the formation of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), increased markedly, which ultimately upregulates iNOS and COX-2. 9,10 It is well known that nuclear factor-κB (NF-κB) is a key transcription factor accounting for induction of various inflammatory genes, including iNOS, COX-2, pro-inflammatory cytokines. 11 Taken together, drugs with an ability to inhibit NF-κB-activated pro-inflammatory gene expression and mediator formation may have a potential to prevent the detrimental consequences of sepsis.…”

Fc gamma receptors are expressed in the developing rat brain and activate downstream signaling molecules upon cross-linking with immune complex

“…Resident peritoneal macrophages were collected from adult female Sprague Dawley rats, plated at a density of 2 × 10 5 cells/cm 2 and maintained as described [ 46 ]. Cells were plated on tissue culture plastic (Thermo Fisher Scientific) and allowed to adhere for 1 h at 37 °C in a 5% CO 2 humidified incubator.…”