Current Medicinal Chemistry (v.16, #6)

Alzheimer's disease (AD) is the leading cause of dementia in the elderly. Although the etiology of AD remains unclear, microglia-mediated neuroinflammation is believed to play an important role in its pathogenesis. Microglial activation occurs in AD and is characterized by apparent phagocytic activity and by increased production and secretion of several cytokines, chemokines, reactive oxygen and nitrogen species, prostaglandin (PG)E2, and neurotrophic factors. Microglial activation can be neuroprotective through the release of neurotrophic factors and by phagocytosing Aand#946;, a critical neurotoxic component in AD brain. Concurrently, microglial activation causes elevated inflammatory responses that lead to paracrine damage to neurons. Therefore, a well-controlled microglial activation that diminishes microglial-mediated oxidative damage while promoting neuronal protection may be the key for AD therapy. Peroxisome proliferator-activated receptor gamma (PPARand#947;) has recently gained increasing attention in AD due to its function as a molecular target for nonsteroidal anti-inflammatory drugs (NSAIDs). In this review, we will discuss the role of PPARand#947; in microglial innate immunity in AD and how pharmacological manipulation of microglial activation using PPARand#947; ligands might facilitate the treatment of AD.

Adult Neurogenesis and the Diseased Brain by Renaud Vandenbosch, Laurence Borgs, Pierre Beukelaers, Shibeshih Belachew, Gustave Moonen, Laurent Nguyen, Brigitte Malgrange (652-666).
For a long time it was believed that the adult mammalian brain was completely unable to regenerate after insults. However, recent advances in the field of stem cell biology, including the identification of adult neural stem cells (NSCs) and evidence regarding a continuous production of neurons throughout life in the dentate gyrus (DG) and the subventricular zone of the lateral ventricles (SVZ), have provided new hopes for the development of novel therapeutic strategies to induce regeneration in the damaged brain. Moreover, proofs have accumulated this last decade that endogenous stem/progenitor cells of the adult brain have an intrinsic capacity to respond to brain disorders. Here, we first briefly summarize our current knowledge related to adult neurogenesis before focusing on the behaviour of adult neural stem/progenitors cells following stroke and seizure, and describe some of the molecular cues involved in the response of these cells to injury. In the second part, we outline the consequences of three main neurodegenerative disorders on adult neurogenesis and we discuss the potential therapeutic implication of adult neural stem/progenitors cells during the course of these diseases.

The Anti Inflammatory Effects of High Density Lipoproteins by A. Murphy, J.P. Chin-Dusting, D. Sviridov, K. Woollard (667-675).
It is well recognised that increased levels of high density lipoprotein (HDL) protect against atherosclerosis and correlate with improved prognosis for vascular disease associated events. While many of the atheroprotective effects of HDL are ascribed to the ability to remove cholesterol from the vasculature through the reverse cholesterol transport system, recent work has shown that HDL may be atheroprotective through its other functions, such as regulation of endothelial adhesion molecule expression, stimulation of endothelial nitric oxide synthase and inhibition of the damaging effects of oxidised low density lipoproteins. Recently, HDL has also been described to interact with circulating cells inhibiting both leukocyte and platelet activation, therefore having further systemic anti-inflammatory functions. This review summarises the studies and models used to examine the anti-inflammatory effects of HDL and details data describing the ability to inhibit leukocyte activation, contributing to the hypothesis that raised HDL is beneficial in the context of inflammation in atherosclerosis. Further, HDL modification in disease and current therapeutic strategies such as reconstituted HDL particles and apoA-I mimetic peptides is discussed to provide insights to the potential applicability of raising HDL to regress cardiovascular disease.

Anti-Inflammatory Effects of Fibrates: An Overview by Konstantinos Tziomalos, Vasilios Athyros, Asterios Karagiannis, Dimitri Mikhailidis (676-684).
Inflammation plays an important role in the pathogenesis of atherosclerosis. Several cardiovascular drugs exert anti-inflammatory effects and accumulating data suggest that fibrates also share this property. This review summarizes the mechanisms implicated in the anti-inflammatory actions of fibrates. We also provide an overview of the existing clinical studies addressing the effects of fibrates on markers of inflammation. Several, but not all, studies reported that fibrates exert anti-inflammatory actions. The small number of patients included in some studies, as well as differences in diagnoses and duration of follow up might partly explain this discrepancy. It is also possible that fibrates differ substantially in terms of anti-inflammatory effects. It is not clear whether an anti-inflammatory action of fibrates is clinically relevant. Future studies should assess whether the anti-inflammatory actions of fibrates (or for that matter, other drugs) will translate into a reduced risk of vascular disease.

Cholesterol Oxidation Products and Disease: An Emerging Topic of Interest in Medicinal Chemistry by Barbara Sottero, Paola Gamba, Simona Gargiulo, Gabriella Leonarduzzi, Giuseppe Poli (685-705).
Oxysterols are a family of 27-carbon cholesterol oxidation derivatives that may be absorbed with the diet or originated endogenously. These cholesterol metabolites are now considered to be potentially involved in the initiation and progression of major chronic diseases including atherosclerosis, neurodegenerative processes, diabetes, kidney failure, and ethanol intoxication. Thus we deemed it of interest to comprehensively analyze the actual relevance of oxysterols, acting through up-regulation of inflammation, apoptosis and fibrosis, to human pathology from cell signaling to disease expression; we also review the available literature on related therapeutic prospects. Oxysterols of pathophysiologic relevance generally possess a strong pro-oxidant effect, chiefly since they activate NAD(P)H oxidases. Further, stimulation of the MEK/ERK signaling pathway appears to be a common feature of the biochemical effects of this class of compounds. Selective metabolic inhibitors of NAD(P)H oxidase and the MAPK pathway might quench or even prevent the cytotoxic effects of pathological accumulation of cholesterol oxides in cells and tissues. The marked reduction of plasma oxysterols reported for statin-based therapy is interesting: it has been associated with a lower incidence and prevalence of Alzheimer's disease (AD) and vascular dementia. Quenching reactive oxygen species' generation seems the likely mechanism exploited by statins against AD incidence and development; intervention with antioxidants might thus also be reconsidered as regards molecular and#x201C;integratedand#x201D; prevention and possible therapy of human and#x201C;multifactorialand#x201D; disease processes.

Protein tyrosine phosphatases (PTPs) are considered to be involved in the etiology of diabetes mellitus, neural diseases such as Alzheimer's and Parkinson's disease, regulation of allergy and inflammation, or they are even considered to be responsible for the pathogens` virulence in vivo. Since discovery of first PTP inhibitors such as dephostatin in early 90th years, the research moved on toward search for inhibitors specific for the individual PTP molecules. Currently, dozens of new PTP inhibitors are reported each year, ranging from natural products, natural product analogs, peptides, phosphonates, nonpeptidic inhibitors, mimotopes, metalcontaining inhibitors, redox inhibitors, to simply silencing RNAs as widely used inhibitors of PTP expression. Several currently used drugs also show PTP inhibitory activity. Among them are sodium stibogluconate, phenylarsine oxide, alendronate, etidronate, vanadate, gallium nitrate, suramin, or aplidin. However, the market is still waiting for the first clinically approved selective PTP inhibitor. Here in this review are described inhibitors of activity or expression of the particular classical PTPs, with emphasis on specific inhibition of the respective PTP over the others. The inhibitors are not classified according to their chemical composition, but according to their biological activity, which should help to simplify search for inhibitors of particular classical PTPs. Even though PTP inhibitors are difficult to develop, lifting the fog of phosphatase inhibition is of the great market potential and further clinical impact.

Aldose Reductase Enzyme and its Implication to Major Health Problems of the 21st Century by Polyxeni Alexiou, Kyriaki Pegklidou, Maria Chatzopoulou, Ioannis Nicolaou, Vassilis Demopoulos (734-752).
Aldose reductase enzyme (ALR2) of the polyol metabolic pathway, apart from its role as detoxifying enzyme towards toxic aldehydes, osmoregulator in the kidney and regulator of sperm maturation, was first found to be implicated in the etiology of the long term diabetic complications. However, to date, emerging reports have suggested that under normal glucose concentration, ALR2 may be up-regulated by factors other than hyperglycemia and therefore be involved also in other pathological processes that have become major threats to human health in the 21st century. Such pathologies are a number of cardiac disorders, inflammation, mood disorders, renal insufficiency and ovarian abnormalities. In addition, ALR2 was found to be over-expressed in different human cancers such as liver, breast, ovarian, cervical and rectal cancers. Although several aldose reductase inhibitors (ARIs) have progressed to the clinical level, only one is currently on the market. Thus, attention is currently targeted to discover ARIs of distinct chemical structures, being neither hydantoin nor carboxylic acid derivatives. The present review focuses on the molecular mechanisms by which ALR2 is implicated in a number of pathologies, on various aspects concerning its catalytic mechanism and its active site, and on the main classes of ARIs that have been developed to date, as well as on reported (quantitive) structure-activity relationships. The presented data aim to support the notion that ARIs are of pharmacotherapeutic interest for the pharmaceutical community and highlight essential aspects for the development of efficient and potent ARIs.

Antibodies for Therapeutic Uses and the Evolution of Biotechniques by P. Nieri, D. Donadio, S. Rossi, B. Adinolfi, A. Podesta (753-779).
Protein therapeutics are playing an expanding role in modern medicinal chemistry. Among them, native or engineered molecules exploiting the binding and catalytic potential of the immune repertoire form an extremely exciting and emerging business area. They represent by far the single largest category of biopharmaceutical substances under investigation. The fast increase of this pharmaceutical category paralleled the scientific and technical progress from murine to chimeric, humanized and, finally, human engineered antibodies. Indeed, the development of the phage display technology, allowing libraries of shuffled murine or human antibody binding domains to be screened for affinity against a selected target antigen or activity against a specific reaction substrate, open new perspectives, disclosing the opportunity to circumvent restrictions inherent to the in vivo immunisation. Transgenic technology represents another powerful method for generating fully human monoclonal antibodies against a wide variety of drug targets, while recombinant technology continues to evolve, improving the pharmacodynamic and pharmacokinetic properties of antibody therapeutics, with the production of different antibody constructs or formats, such as bispecific antibodies, diabodies and others, and different functional activities, such as catalysis, cellular internalisation and antigen-mimicking. The aim of the present review is to overview native or recombinant antibodies while discussing the underlying antibody technology, with the aim to favour understanding of the antibody therapeutics that are in use or will enter market in the near future.