Inhibitory effects of thalidomide on cellular proliferation, endoneurial edema and myelin phagocytosis during early wallerian degeneration

The effect of thalidomide on vascular endothelial growth factor and tumor necrosis factor-alpha levels in retinal ischemia/reperfusion injury

BACKGROUND

To evaluate the effects of thalidomide treatment on the temporal course of TNF-alpha, VEGF production and the histopathological changes in ischemia/reperfusion (I/R) injured guinea pigs retina.

METHODS

Control, ischemia, and thalidomide/ischemia groups including seven animals each were formed. Retinal ischemia was induced in male guinea pigs by cannulating anterior chambers and lifting the bottle to a height of 205 cm for 90 min in the ischemia and thalidomide/ischemia groups. The thalidomide/ischemia group received thalidomide (300 mg/kg/day) via nasogastric tube 24 h before ischemia and during 7 days of reperfusion. Guinea pigs were sacrificed for histopathological examination to evaluate the mean thickness of the inner plexiform layer (IPL), polymorphonuclear leukocyte (PMNL) infiltration, and biochemical analysis of retinal VEGF and TNF-alpha levels by ELISA.

RESULTS

The mean retinal VEGF and TNF-alpha levels of the control, ischemia, and thalidomide/ischemia groups were 10.22 +/- 2.58 and 270.41 +/- 69.77 pg/ml; 35.80 +/- 5.97 and 629.93 +/- 146.41 pg/ml; 19.01 +/- 3.01 and 340.93 +/- 158.26 pg/ml, respectively. The retinal VEGF levels were significantly higher in I/R injured groups. The thalidomide/ischemia group retinal VEGF level was significantly lower versus the ischemia group. The retinal TNF-alpha levels were significantly elevated in the ischemia group, but no difference was observed between the thalidomide/ischemia and control groups. Also, the retinal TNF-alpha level was significantly lower in the thalidomide/ischemia group versus the ischemia group. The mean thickness of IPL and PMNL infiltration showed no difference between the control and thalidomide/ischemia groups. However, there was a significant difference between the control and ischemia groups.

CONCLUSION

Thalidomide treatment decreases PMNL infiltration, retinal edema, VEGF, and TNF-alpha synthesis following I/R injury to the guinea pig retina.

Thalidomide in dermatology

Thalidomide is an effective agent to treat over 25 seemingly unrelated dermatological conditions that have an inflammatory or autoimmune basis. The main side-effects of teratogenesis and peripheral neuropathy limit its use. Currently, in Australia no assurance is given as to the quality, safety and efficacy of thalidomide. The use of thalidomide for toxic epidermal necrolysis can lead to an increase in mortality, and its use as a prophylactic agent for the prevention of chronic graft-versus-host disease following bone marrow transplantation has raised more speculations as to the safety of this notorious drug. A review of the therapeutic indications for thalidomide in dermatology as well as the mechanisms of action and side-effects of this drug are presented. The current suggested guidelines for its use in clinical practice in Australia are discussed.

Antiproliferative effect of thalidomide alone and combined with carmustine against C6 rat glioma

Thalidomide could have therapeutic applications in neoplasms and in other diseases, particularly those of autoimmune origin. The objective of this study was to investigate the effect of various doses of thalidomide on the growth of C6 glioma in rats, and to determine its effects on parameters of cell proliferation and angiogenesis. Additionally, we investigated a potential enhancement of the antitumoral action of thalidomide when combined with a low dose of the antineoplastic carmustine. C6 glioma cells were implanted subcutaneously in Wistar rats. A highly malignant glioma developed in 80% of animals. When the tumour reached 2.0 cm diameter thalidomide was administered at doses of 100, 200 or 400 mg/kg/day. When given at a dose of 400 mg/kg/day thalidomide significantly reduced the tumour volume, the mitotic index and cell proliferation but not the vascular density. The combination of thalidomide plus carmustine increased the inhibitory effect on tumoral growth. Our results indicate that thalidomide is effective against malignant glioma; apparently by an antiproliferative effect, rather than by inhibition of angiogenesis; when combined with carmustine it could increase the response of glioma to antineoplastic treatment.

Concentration-dependent effects of pentoxifylline on migration and myelin phagocytosis by macrophages

The effects of pentoxifylline (POX) on macrophage migration and myelin uptake were studied in an in vitro model of myelin phagocytosis. The POX is a phosphodiesterase inhibitor which inhibits TNF-alpha (tumor necrosis factor alpha) production and reduces ICAM-1 (intercellular adhesion molecule-1) expression by macrophages. Both of these molecules have earlier been shown to be involved in the process of myelin recognition and degradation. In the present series of experiments, cocultured peripheral nerves and macrophages were treated with different concentrations of POX. Untreated controls were massively invaded by macrophages which ingested the degenerating myelin sheaths. High concentrations of POX (100 microg ml(-1)) inhibited macrophage invasion of the nerves. Lower POX concentrations (50 microg ml(-1)), in contrast, lead to an increased myelin uptake by phagocytic cells without affecting macrophage migration. These data indicate that POX may regulate different effector functions of macrophages such as migration and myelin phagocytosis during Wallerian degeneration. This is important for inflammatory demyelinating conditions in the central or peripheral nervous system (PNS) in which macrophages are also important effector cells. Since POX is used as an immunomodulatory drug in demyelinating diseases, its effects on the described macrophage functions may be of high relevance. An increased myelin uptake during Wallerian degeneration may also support a more efficient axonal regeneration by removing axonal outgrowth inhibitors.

Rediscovering thalidomide: a review of its mechanism of action, side effects, and potential uses

Thalidomide, a hypnosedative drug introduced in the 1950s, has been used in a variety of dermatologic conditions during the past few decades. Although originally withdrawn from the world market on discovery of its teratogenic effect, it has since been selectively reintroduced for use in various disorders thought to have an autoimmune or inflammatory basis. A review of the literature focused on clinical uses of thalidomide in the treatment of dermatologic diseases was performed. Diseases for which thalidomide has been found effective include erythema nodosum leprosum, prurigo nodularis, actinic prurigo, discoid lupus erythematosus, aphthous stomatitis, Behçet's syndrome, and graft-versus-host disease. Side effects such as teratogenicity and peripheral neuropathy remain its limiting factor. Thalidomide is a useful addition to the therapeutic armamentarium for treatment-resistant dermatoses as long as proper vigilance for adverse effects is maintained.