GLC756 decreases TNF-alpha via an alpha2 and beta2 adrenoceptor related mechanism

Monoamine Oxidase Inhibitors: A Review of Their Anti-Inflammatory Therapeutic Potential and Mechanisms of Action

Chronic inflammatory diseases are debilitating, affect patients' quality of life, and are a significant financial burden on health care. Inflammation is regulated by pro-inflammatory cytokines and chemokines that are expressed by immune and non-immune cells, and their expression is highly controlled, both spatially and temporally. Their dysregulation is a hallmark of chronic inflammatory and autoimmune diseases. Significant evidence supports that monoamine oxidase (MAO) inhibitor drugs have anti-inflammatory effects. MAO inhibitors are principally prescribed for the management of a variety of central nervous system (CNS)-associated diseases such as depression, Alzheimer's, and Parkinson's; however, they also have anti-inflammatory effects in the CNS and a variety of non-CNS tissues. To bolster support for their development as anti-inflammatories, it is critical to elucidate their mechanism(s) of action. MAO inhibitors decrease the generation of end products such as hydrogen peroxide, aldehyde, and ammonium. They also inhibit biogenic amine degradation, and this increases cellular and pericellular catecholamines in a variety of immune and some non-immune cells. This decrease in end product metabolites and increase in catecholamines can play a significant role in the anti-inflammatory effects of MAO inhibitors. This review examines MAO inhibitor effects on inflammation in a variety of in vitro and in vivo CNS and non-CNS disease models, as well as their anti-inflammatory mechanism(s) of action.

Neuroprotection in glaucoma - Is there a future role?

In glaucoma, the major cause of global irreversible blindness, there is an urgent need for treatment modalities that directly target the RGCs. The discovery of an alternative therapeutic approach, independent of IOP reduction, is highly sought after, due to the indirect nature and limited effectiveness of IOP lowering therapy in preventing RGC loss. Several mechanisms have been implicated in initiating the apoptotic cascade in glaucomatous retinopathy and numerous drugs have been shown to be neuroprotective in animal models of glaucoma. These mechanisms and their potential treatment include excitotoxicity, protein misfolding, mitochondrial dysfunction, oxidative stress, inflammation and neurotrophin deprivation. All of these mechanisms ultimately lead to programmed cell death with loss of RGCs. In this article we summarize the mechanisms involved in glaucomatous disease, highlight the rationale for neuroprotection in glaucoma management and review current potential neuroprotective strategies targeting RGCs from the laboratory to the clinic.

Antiglaucoma drug GLC756 and its effect on cellular cAMP and tumor necrosis factor alpha release in vitro of activated human monocytic leukemia cells

PURPOSE

GLC756, a putative antiglaucoma drug with dopamine D(2) agonist and D(1) antagonist properties, significantly decreases tumor necrosis factor alpha (TNF-alpha) levels in lipopolysaccharide (LPS)-induced rats. The present study describes the effects of GLC756 on cellular adenosine 3', 5'-cyclic monophosphate (cAMP) in relation to TNF-alpha production on LPS-stimulated human acute monocytic leukemia cells.

METHODS

A human peripheral blood acute monocytic leukemia cell line (THP-1) was activated via LPS. THP-1 cells were incubated with GLC756 or betamethasone (positive control) at concentrations of 1, 10, and 30 microM. The TNF-alpha concentration in supernatant and cAMP levels in cellular extract were measured by enzyme-linked immunosorbent assay 0,1, 2.5, 4.5, 7, and 24 h post-activation.

RESULTS

Compared with LPS controls, both GLC756 at 30 muM and betamethasone at > or =1 microM had a significant inhibitory effect on TNF-alpha release from THP-1 cells 2.5 to 24 h post-activation. Parallel to the TNF-alpha decrease, GLC756 induced significant increases of cellular cAMP 2.5 and 7 h post-activation. Betamethasone had no effect on the cellular cAMP level.

CONCLUSION

Intracellular signaling pathway leading to inhibition of the production of the proinflammatory cytokine TNF-alpha after GLC756 treatment might be mediated through the second messenger cAMP.

Neuroprotection in glaucoma: drug-based approaches

In recent years the focus of glaucoma research has shifted toward neuroprotection, as the traditional strategies of lowering intraocular pressure have been shown to be unable to prevent progressive vision loss in some glaucoma patients. As a result various neuroprotective drug-based approaches have been shown capable of reducing the death of retinal ganglion cells, which is the hallmark of glaucomatous optic neuropathy. There has been increasing evidence that glaucomatous neurodegeneration is analogous to other neurodegenerative diseases in the central nervous system, with recent work from our group elucidating a strong link between basic cellular processes in glaucoma and Alzheimer's disease. Additionally, there is a growing trend for using existing neuroprotective strategies in central nervous system diseases for the treatment of glaucoma. In fact, a trial treating patients with primary open-angle glaucoma with memantine, a drug approved for the treatment of Alzheimer's disease, has recently been completed. Results of this trial are not yet available. In this review, we will examine currently advocated neuroprotective drug-based strategies in the potential management of glaucoma.