Novel small molecules inhibit proteotoxicity and inflammation: Mechanistic and therapeutic implications for Alzheimer’s Disease, healthspan and lifespan- Aging as a consequence of glycolysis

Abstract

Alzheimers Disease (AD) and other age-related diseases are increasingly among the most devastating strains on public health systems as the population ages, yet few treatments produce clinically significant protection. Although it is widely agreed that proteotoxicity drives impairments in AD and other neurological diseases, many preclinical and case-report studies indicate that increased microglial production of pro-inflammatory cytokines such as TNF-a also drive AD and other neurological conditions. The critical importance of inflammation, especially TNF-a, in driving age-related diseases is indicated by the fact that Humira, simply a monoclonal antibody to TNF-a, has become the top-selling drug in history, even though it does not cross the blood-brain barrier. Since target-based strategies to discover drugs to treat these diseases have largely failed, we developed parallel high-throughput phenotypic screens to discover small molecules which inhibit age-related proteotoxicity in a C. elegans model of AD, AND microglia inflammation (LPS-induced TNF-a). In the initial screen of 2560 compounds to delay Abeta proteotoxicity in C. elegans, the most protective compounds were, in order, phenylbutyrate (HDAC inhibitor), methicillin (beta lactam antibiotic), and quetiapine (tricyclic antipsychotic). These classes of compounds are already robustly implicated as potentially protective in AD and other neurodegenerative diseases. In addition to quetiapine, several other tricyclic antipsychotic drugs also delayed age-related Abeta proteotoxicity and microglial TNF-a. Based on these results we carried out extensive structure-activity relationship studies, leading to the synthesis of a novel congener of quetiapine, #310, which inhibits a wide range of pro-inflammatory cytokines in mouse and human myeloid cells, and delays impairments in animal models of AD, Huntingtons, and stroke. #310 is highly concentrated in brain after oral delivery with no apparent toxicity, increases lifespan, and produces molecular responses highly similar to those produced by dietary restriction. Among these molecular responses are induction of CBP and inhibition of CtBP and CSPR1, and inhibition of glycolysis, reversing gene expression profiles and elevated glycolysis associated with AD. Several lines of investigation strongly supported that the protective effects of #310 are mediated by activating the Sigma-1 receptor, whose protective mechanisms in turn also entail inhibiting glycolysis. Reduced glycolysis has also been implicated in the generally protective effects of dietary restriction, rapamycin, reduced IFG-1 activity, and ketones during aging, suggesting that aging is driven at least in part by glycolysis. Consistent with these observations, the glycolytic inhibitor 2-DG inhibited microglial TNF-a and other markers of inflammation, delayed Abeta proteotoxicity, and increased lifespan. To our knowledge no other known molecule exhibits all these protective effects which makes #310 an attractive candidate to treat AD and other age-related diseases. Indeed it is plausible that #310 or possibly even more effective congeners could displace Humira as a widely used therapy for age-related diseases. Furthermore, these studies suggest that the efficacy of tricyclic compounds to treat psychosis and depression could be due to their anti-inflammatory effects mediated by the Sigma-1 receptor, rather than the D2 receptor, and that better drugs to treat these conditions with fewer metabolic side effects could be developed by focusing on the Sigma-1 receptor rather than the D2 receptor. These results strongly support the value of phenotypic screens to discover drugs to treat AD and other age-related diseases and to elucidate mechanisms driving those diseases.