Therapeutic Perspectives of Adenosine Deaminase Inhibition in Cardiovascular Diseases

Adenosine deaminase (ADA) is an enzyme of purine metabolism that irreversibly converts adenosine to inosine or 2'deoxyadenosine to 2'deoxyinosine. ADA is active both inside the cell and on the cell surface where it was found to interact with membrane proteins, such as CD26 and adenosine receptors, forming ecto-ADA (eADA). In addition to adenosine uptake, the activity of eADA is an essential mechanism that terminates adenosine signaling. This is particularly important in cardiovascular system, where adenosine protects against endothelial dysfunction, vascular inflammation, or thrombosis. Besides enzymatic function, ADA protein mediates cell-to-cell interactions involved in lymphocyte co-stimulation or endothelial activation. Furthermore, alteration in ADA activity was demonstrated in many cardiovascular pathologies such as atherosclerosis, myocardial ischemia-reperfusion injury, hypertension, thrombosis, or diabetes. Modulation of ADA activity could be an important therapeutic target. This work provides a systematic review of ADA activity and anchoring inhibitors as well as summarizes the perspectives of their therapeutic use in cardiovascular pathologies associated with increased activity of ADA.

Curcumin improves episodic memory in cadmium induced memory impairment through inhibition of acetylcholinesterase and adenosine deaminase activities in a rat model

Curcumin, the main polyphenolic component of turmeric (Curcuma longa) rhizomes has been reported to exert cognitive enhancing potential with limited scientific basis. Hence, this study sought to evaluate the effect of curcumin on cerebral cortex acetylcholinesterase (AChE) and adenosine deaminase (ADA) activities in cadmium (Cd)-induced memory impairment in rats. Animals were divided into six groups (n = 6): saline/vehicle, saline/curcumin 12.5 mg/kg, saline/curcumin 25 mg/kg, Cd/vehicle, Cd/curcumin 12.5 mg/kg, and Cd/curcumin 25 mg/kg. Rats received Cd (2.5 mg/kg) and curcumin (12.5 and 25 mg/kg, respectively) by gavage for 7 days. The results of this study revealed that cerebral cortex AChE and ADA activities were increased in Cd-poisoned rats, and curcumin co-treatment reversed these activities to the control levels. Furthermore, Cd intoxication increased the level of lipid peroxidation in cerebral cortex with a concomitant decreased in functional sulfuhydryl (-SH) group and nitric oxide (NO), a potent neurotransmitter and neuromodulatory agent. However, the co-treatment with curcumin at 12.5 and 25 mg/kg, respectively increased the non-enzymatic antioxidant status and NO in cerebral cortex with a decreased in malondialdehyde (MDA) level. Therefore, inhibition of AChE and ADA activities as well as increased antioxidant status by curcumin in Cd-induced memory dysfunction could suggest some possible mechanism of action for their cognitive enhancing properties.

Pentostatin as rescue therapy for glucocorticoid-refractory acute and chronic graft-versus-host disease

BACKGROUND

Despite scientific advances in hematopoietic cell allografting, glucocorticoid-refractory acute (aGVHD) and chronic graft-versus-host disease (cGVHD) represent major sources of transplant-related morbidity and mortality. We aimed to characterize the activity of pentostatin as rescue therapy for refractory GVHD.

MATERIAL/METHODS

In a retrospective analysis, we examined the activity of pentostatin as rescue therapy of glucocorticoid-refractory acute and chronic GVHD.

RESULTS

In 12 patients with advanced (overall aGVHD grade III/IV in 8/12) refractory aGVHD, overall response (ORR) was achieved in 6/12, and complete remission (CR) of aGVHD in 4/12 allowing additional rescue immunosuppressive agents. Median overall survival (OS) was 1.4 months (95% CI: 0.26-2.4). Causes of death included refractory aGVHD and infection. In 18 patients with refractory cGVHD (12/18 with severe cGVHD), pentostatin induced CR in 1/18, and partial response (PR) in 9/18. Activity was observed in all affected organs. The median decrease in glucocorticoid therapy over 24 months after pentostatin initiation for refractory cGVHD was 38% (range=0-100%). Median OS was 5 months (95% CI: 1.6 - NR).

CONCLUSIONS

Allowing for the utilization of additional immune suppressive agents, this series suggests the activity of pentostatin as rescue therapy of refractory GVHD.