Brain network dysfunction in Alzheimer's disease (AD) involves many proteins (enzymes), processes and pathways, which overlap and influence one another in AD pathogenesis. This complexity challenges ...the dominant paradigm in drug discovery or a single-target drug for a single mechanism. Although this paradigm has achieved considerable success in some particular diseases, it has failed to provide effective approaches to AD therapy. Network medicines may offer alternative hope for effective treatment of AD and other complex diseases. In contrast to the single-target drug approach, network medicines employ a holistic approach to restore network dysfunction by simultaneously targeting key components in disease networks. In this paper, we explore several drugs either in the clinic or under development for AD therapy in term of their design strategies, diverse mechanisms of action and disease-modifying potential. These drugs act as multi-target ligands and may serve as leads for further development as network medicines.
In this study, we examined the possibility of introducing methotrexate (MTX) to the carboxylate rather than to the ε-amino side chains of proteins. We found that MTX-amino compounds covalently linked ...to the carboxylate moieties of macromolecules, undergo unusual peptide-bond cleavage, with the release of the MTX amino derivatives from the conjugates. This event takes place at an accelerated rate under acidic conditions, and at a slower rate at physiological pH values. The glutamate portion of MTX is responsible for this behavior, with little or no contribution of the p-aminobenzoate-pteridine ring that is linked to the α-amino side chain of the glutamate. Carboxylate-linked Fmoc-Glu-γ-CONH-(CH2)6-NH2 undergoes hydrolysis in a nearly indistinguishable fashion. A free α carboxylate moiety is essential for this effect. Carboxylate linked Fmoc-glutamic-amide-γ-CONH-(CH2)6-NH2 undergoes no hydrolysis under acidic conditions. Based on these findings, we engineered a cysteine specific MTX containing reagent. Its linkage to bovine serum albumin (BSA) yielded a conjugate with profound antiproliferative efficacy in a MTX-sensitive glioma cell line. In conclusion, carboxylate linked MTX-amino derivatives in particular, and carboxylate linked R-α-GLU-γ amino compounds in general are equipped with'built-in chemical machinery' that releases them under mild acidic conditions.
A family of monomodified bovine serum albumin (BSA) linked to methotrexate (MTX) through a variety of spacers was prepared. All analogues were found to be prodrugs having low MTX-inhibitory potencies ...toward dihydrofolate reductase in a cell-free system. The optimal conjugates regenerated their antiproliferative efficacies following entrance into cancerous glioma cell lines and were significantly superior to MTX in an insensitive glioma cell line. A BSA-MTX conjugate linked through a simple ethylene chain spacer, containing a single peptide bond located 8.7 Å distal to the protein back bone, and apart from the covalently linked MTX by about 12 Å, was most effective. The inclusion of an additional disulfide bond in the spacer neither enhanced nor reduced the killing potency of this analogue. Disrupting the native structure of the carrier protein in the conjugates significantly reduced their antiproliferative activity. In conclusion, we have engineered BSA-MTX prodrug analogues which undergo intracellular reactivation and facilitate antiproliferative activities following their entrance into glioma cells.
A novel small molecule named tuftsin-phosphorylcholine (TPC), which is linked to the biological activity of helminths, was constructed. The current study address the effect of TPC treatment in ...established collagen-induced arthritis (CIA) mice and propose TPC bi-functional activity. TPC treatment was initiated when clinical score was 2 to 4. Arthritis scores in TPC treated mice were lower compared to mice treated with vehicle (P < 0.001). Joint staining showed normal joint structure in TPC-treated mice compared to control groups treated with phosphate buffered saline (PBS), phosphorylcholine, or tuftsin, which exhibited severely inflamed joints. TPC enhanced anti-inflammatory response due to increased IL-10 secretion, and reduced pro-inflammatory cytokine secretion (IL-1-β, IL-6, TNF-αP < 0.001). Furthermore, TPC therapy increased expansion of CD4+CD25+FOXP3+T regulatory cells and IL-10+CD5+CD1d+B regulatory cells. We propose that the immunomodulatory activity of TPC can be a result of a bi-specific activity of TPC: (a) The tuftsin part of the TPC shifts RAW macrophage cells from pro-inflammatory macrophages M1 to anti-inflammatory M2-secreting IL-10 (P < 0.001) through neuropilin-1 and (b) TPC significantly reduce mouse TLR4 expression via NFkB pathway by HEKTM cells (P < 0.02) via the phosphorylcholine site of the molecule. Our results indicate that TPC, significantly ameliorated established CIA by its immunomodulatory activity. These data could lead to a novel self bi-functional small molecule for treating patients with progressive RA.
Rheumatoid arthritis (RA) is characterized by chronic autoinflammation of the joints, with a prevalence of about 1% in Western populations. Evidence in recent years has linked RA to changes in the ...gut microbiota (dysbiosis). Interestingly, helminths have been shown to have therapeutic activity in RA. Specifically, a glycoprotein containing phosphorylcholine (PC) extracted from helminths was found to have immunomodulatory activity. We have previously developed a novel chimeric compound composed of tuftsin-PC (TPC) that attenuates the joint destruction in mice with collagen-induced arthritis (CIA). Here, we address the interrelationship between TPC immunomodulatory activity and the gut microbiota in CIA mice. Preventive therapy with TPC in mice with arthritis maintained a physiological arthritis score as well as a steady gut microbial environment, similar to that of healthy controls, in contrast to CIA mice with severe disease. The microbial composition differed significantly between healthy and phosphate-buffered saline-treated CIA mice, enabling classifying test samples by machine learning based on levels of a small number of bacterial species. Using these bacterial biomarkers, all TPC-treated CIA mice were classified as healthy. Thus, we describe a clear correlation between TPC treatment, healthy gut microbial communities, and prevention of arthritis. This is the first study to demonstrate the immunomodulatory effect of helminth derivatives in autoimmune diseases and the link to gut microbiota.
To date, no truly efficacious drugs for Alzheimer's disease (AD) have been developed; moreover, all new anti-AD drugs developed since 2003 have failed. To succeed where previous ones have failed in ...drug development, new approaches for AD therapy are needed. Here we discuss the potential application of network medicine as a new approach to AD treatment. Unlike traditional approaches focused on a single target/pathway, network medicine targets and restores disease-disrupted networks through simultaneous modulation of numerous proteins (targets)/pathways involved in AD pathogenesis. We consider several drug candidates under development for AD therapy, including Keap1–Nrf2 regulators, endogenous neurogenic agents, and hypoxia-inducible factor 1 (HIF-1) activators. These drug candidates are multi-target ligands with the potential to further develop as network medicines, since they act as master regulators to initiate a broad range of cellular defense mechanisms/cytoprotective genes that exert their efficacy in a holistic way. We also explore their diverse mechanisms of action and potential disease-modifying effects, which may have profound implications for drug discovery.
Chelators have the potential to treat the underlying cause of Alzheimer’s disease (AD), but their therapeutic use is hampered by their poor targeting and poor permeability to the brain and/or toxic ...effects. Here, we report a new strategy for designing site-activated chelators targeting both acetylcholinesterase (AChE) and monoamine oxidase (MAO). We demonstrated that our lead 2 inhibited both AChE and MAO in vitro, but with little affinity for metal (Fe, Cu, and Zn) ions. Compound 2 can be activated by inhibition of AChE to release an active chelator M30. M30 has been shown to be able to modulate amyloid precursor protein regulation and β-amyloid reduction, suppress oxidative stress, and passivate excess metal ions (Fe, Cu, and Zn). Compound 2 was less cytotoxic and more lipophilic than the brain-permeable chelator M30. Our new strategy is relatively simple and generally produces small and simple molecules with drug-like properties; it thus holds a potential use in designing site-activated multifunctional chelators with safer and more efficacious properties for treating other metal-related diseases such as Parkinson’s disease and cancer where specific elimination of metals in cancer cells is required.
Iron‐dependent oxidative stress, elevated levels of iron and of monoamine oxidase (MAO)‐B activity, and depletion of antioxidants in the brain may be major pathogenic factors in Parkinson's disease, ...Alzheimer's disease and related neurodegenerative diseases. Accordingly, iron chelators, antioxidants and MAO‐B inhibitors have shown efficacy in a variety of cellular and animal models of CNS injury. In searching for novel antioxidant iron chelators with potential MAO‐B inhibitory activity, a series of new iron chelators has been designed, synthesized and investigated. In this study, the novel chelators were further examined for their activity as antioxidants, MAO‐B inhibitors and neuroprotective agents in vitro. Three of the selected chelators (M30, HLA20 and M32) were the most effective in inhibiting iron‐dependent lipid peroxidation in rat brain homogenates with IC50 values (12–16 µm), which is comparable with that of desferal, a prototype iron chelator that is not has orally active. Their antioxidant activities were further confirmed using electron paramagnetic resonance spectroscopy. In PC12 cell culture, the three novel chelators at 0.1 µm were able to attenuate cell death induced by serum deprivation and by 6‐hydroxydopamine. M30 possessing propargyl, the MAO inhibitory moiety of the anti‐Parkinson drug rasagiline, displayed greater neuroprotective potency than that of rasagiline. In addition, in vitro, M30 was a highly potent non‐selective MAO‐A and MAO‐B inhibitor (IC50 < 0.1 µm). However, HLA20 was more selective for MAO‐B but had poor MAO inhibition, with an IC50 value of 64.2 µm. The data suggest that M30 and HLA20 might serve as leads in developing drugs with multifunctional activities for the treatment of various neurodegenerative disorders.
The common use of dental and orthopedic implants calls for special attention to the immune response leading to peri-prosthetic bone loss and implant failure. In addition to the well-established ...microbial etiology for oral implant failure, wear debris and in particular titanium (Ti) particles (TiP) in the implant vicinity are an important trigger of inflammation and activation of bone resorption around oral and orthopedic implants, presenting an unmet medical need. Here, we employed bacterial-derived lipopolysaccharides (LPS) to model infection and TiP to model aseptic inflammation and osteolysis. We assessed inflammation
in vitro
by measuring
IL1β
,
IL6
and
TNFα
mRNA expression in primary macrophages, osteoclastogenesis in RANKL-induced bone marrow derived pre-osteoclasts and osteolysis
in vivo
in a mouse calvarial model. We also assessed the trans-epithelial penetrability and safety of the tested compound in rats. Our results show that a lipophilic super-active derivative of vasoactive intestinal peptide (VIP), namely stearyl-norleucine-VIP (SNV) presented superior anti-inflammatory and anti-osteoclastogenic effects compared to VIP
in vitro
. In the bacterial infection model (LPS), SNV significantly reduced IL1β expression, while VIP increased IL6 expression. In the aseptic models of osteolysis, SNV showed greater suppression of
in vitro
osteoclastogenesis than VIP, and significantly inhibited inflammation-induced osteolysis
in vivo
. We also observed that expression levels of the VIP receptor VPAC-2, but not that of VPAC-1, dramatically decreased during osteoclast differentiation. Importantly, SNV previously shown to have an increased stability compared to VIP, showed here significant trans-epithelial penetration and a clean toxicological profile, presenting a novel drug candidate that could be applied topically to counter both aseptic and infection-related bone destruction.
Several novel antioxidant iron chelators bearing 8-hydroxyoxyquinoline moiety were synthesized, and their various properties related to neuroprotective action were investigated.
Several novel ...antioxidant-iron chelators bearing 8-hydroxyoxyquinoline moiety were synthesized, and various properties related to their iron chelation, and neuroprotective action were investigated. All the chelators exhibited strong iron(III) chelating and high antioxidant properties. Chelator
9 (HLA20), having good permeability into K562 cells and moderate selective MAO-B inhibitory activity (IC
50 110
μM), displayed the hightest protective effects against differentiated P19 cell death induced by 6-hydroxydopamine. EPR studies suggested that Chelator
9 also act as radical scavenger to directly scavenge hydroxyl radical.
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