The Adenosine Neuromodulation System in Schizophrenia
ADENOSINE RECEPTORS IN NEUROLOGY AND PSYCHIATRY
Authors: Rial, Daniel; Lara, Diogo R.; Cunha, Rodrigo A.
Abstract
The management of schizophrenia endophenotypes, namely positive, negative, and cognitive symptoms is still an open goal, justifying the search of novel therapeutic avenues. We now review the evidence supporting the interest in targeting the adenosine modulation system to counteract the core features of schizophrenia. This interest is forwarded by the combined ability of strategies aimed at bolstering adenosine levels together with the increasingly recognized impact of adenosine A(2A) receptors to control dopaminergic signaling, working memory, and behavioral sensitization; this is further heralded by the suggested clinical effectiveness of therapies increasing extracellular adenosine such as dipyridamole and allopurinol and the emergent recognition of a role for adenosine in neurodevelopment. Finally, the combined role of A(1) and A(2A) receptors in assisting the implementation of adaptive changes and encoding of information salience in neuronal circuits together with the adaptive alterations of A(1) and A(2A) receptor density upon brain dysfunction, prompts the novel working hypothesis that the parallel imbalance of adenosine formation and of A(1) and A(2A) receptors blurs the adequate encoding of information salience in neuron-al circuits, which we propose to be a core pathogenic feature in the development of schizophrenia endophenotypes. This proposal should also provide a rationale to assist the design of future therapeutic intervention targeting the adenosine modulation system to manage schizophrenia endophenotypes: these should not be based only on an attempt to target adenosine kinase-A(1) receptors or only A(2A) receptors, but should instead simultaneously target these two arms of the adenosine modulation system.
Moving toward personalized medicine in rheumatoid arthritis: SNPs in methotrexate intracellular pathways are associated with methotrexate therapeutic outcome
PHARMACOGENOMICS
Authors: Lima, Aurea; Bernardes, Miguel; Azevedo, Rita; Seabra, Vitor; Medeiros, Rui
Abstract
Aim: Evaluate the potential of selected SNPs as predictors of methotrexate (MTX) therapeutic outcome. Patients & methods: In total, 35 SNPs in 14 genes involved in MTX intracellular pathways and Phase II reactions were genotyped in 233 rheumatoid arthritis (RA) patients treated with MTX. Binary logistic regressions were performed by genotype/haplotype-based approaches. Non-Response-and Toxicity-Genetic Risk Indexes (Non-RespGRI and ToxGRI) were created. Results: MTX nonresponse was associated to eight genotypes and three haplotypes: MTHFR rs1801131 AA and rs1801133 TT; MS rs1805087 AA; MTRR rs1801394 A carriers; ATIC rs2372536 C carriers, rs4673993 T carriers, rs7563206 T carriers and rs12995526 T carriers; CC for GGH rs3758149 and rs12681874; CGTTT for ATIC combination 1; and CTTTC for ATIC combination 2. From overall Non-RespGRI patients with indexes 6-8 had more than sixfold increased risk for MTX nonresponse than those patients with indexes 0-5. MTX-related toxicity was associated to five genotypes and two haplotypes: ATIC rs2372536 G carriers, rs3821353 T carriers, rs7563206 CC and rs12995526 CC; ADORA2A rs2267076 T; CTTCC for ATIC combination 1; and TC for ADORA2A rs2267076 and rs2298383. From overall ToxGRI, patients with indexes 3-4 had more than sevenfold increased risk for MTX-related toxicity than those patients with indexes 1-2. Conclusion: Genotyping may be helpful to identify which RA patients will not benefit from MTX treatment and, consequently, important to personalized medicine in RA. Nevertheless, further studies are required to validate these findings.