Project description:Glycolysis controls cellular energy, redox balance, and biosynthesis. Antiglycolytic therapies are under investigation for treatment of obesity, cancer, aging, autoimmunity, and microbial diseases. Interrupting glycolysis is highly valued as a therapeutic strategy, because glycolytic disruption is generally tolerated in mammals. Unfortunately, anemia is a known dose-limiting side effect of these inhibitors and presents a major caveat to development of antiglycolytic therapies. We developed specific inhibitors of enolase - a critical enzyme in glycolysis - and validated their metabolic and cellular effects on human erythrocytes. Enolase inhibition increases erythrocyte susceptibility to oxidative damage and induces rapid and premature erythrocyte senescence, rather than direct hemolysis. We apply our model of red cell toxicity to address questions regarding erythrocyte glycolytic disruption in the context of Plasmodium falciparum malaria pathogenesis. Our study provides a framework for understanding red blood cell homeostasis under normal and disease states and clarifies the importance of erythrocyte reductive capacity in malaria parasite growth.
Project description:Intracellular infiltration of bacteria into host cells complicates medical and surgical treatment of bacterial joint infections. Unlike soft tissue infections, septic arthritis and infection-associated inflammation destroy cartilage that does not regenerate once damaged. Herein, we show that glycolytic pathways are shared by methicillin-resistant Staphylococcus aureus (MRSA) proliferation and host inflammatory machinery in septic arthritis. MRSA readily penetrates host cells and induces pro-inflammatory cascades that persist after conventional antibiotic treatment. The glycolysis-targeting drug dimethyl fumarate (DMF) showed both bacteriostatic and anti-inflammatory effects by hindering the proliferation of intracellular MRSA and dampening excessive intraarticular inflammation. Combinatorial treatment with DMF and vancomycin further reduced the proliferation and re-emergence of intracellular MRSA. Combinatorial adjuvant administration of DMF with antibiotics alleviated clinical symptoms of septic arthritis by suppressing bacterial burden and curbing inflammation to protect cartilage and bone. Our results provide mechanistic insight into the regulation of glycolysis in the context of infection and host inflammation towards development of a novel therapeutic paradigm to ameliorate joint bioburden and destruction in septic arthritis.
Project description:Intracellular infiltration of bacteria into host cells complicates medical and surgical treatment of bacterial joint infections. Unlike soft tissue infections, septic arthritis and infection-associated inflammation destroy cartilage that does not regenerate once damaged. Herein, we show that glycolytic pathways are shared by methicillin-resistant Staphylococcus aureus (MRSA) proliferation and host inflammatory machinery in septic arthritis. MRSA readily penetrates host cells and induces proinflammatory cascades that persist after conventional antibiotic treatment. The glycolysis-targeting drug dimethyl fumarate (DMF) showed both bacteriostatic and anti-inflammatory effects by hindering the proliferation of intracellular MRSA and dampening excessive intraarticular inflammation. Combinatorial treatment with DMF and vancomycin further reduced the proliferation and re-emergence of intracellular MRSA. Combinatorial adjuvant administration of DMF with antibiotics alleviated clinical symptoms of septic arthritis by suppressing bacterial burden and curbing inflammation to protect cartilage and bone. Our results provide mechanistic insight into the regulation of glycolysis in the context of infection and host inflammation toward development of a novel therapeutic paradigm to ameliorate joint bioburden and destruction in septic arthritis.
Project description:Ensuring continued success against malaria depends on a pipeline of new antimalarials. Antimalarial drug development utilizes preclinical murine and experimental human malaria infection studies to evaluate drug efficacy. A sequential approach is typically adapted, with results from each stage informing the design of the next stage of development. The validity of this approach depends on confidence that results from murine malarial studies predict the outcome of clinical trials in humans. Parasite clearance rates following treatment are key parameters of drug efficacy. To investigate the validity of forward predictions, we developed a suite of mathematical models to capture parasite growth and drug clearance along the drug development pathway and estimated parasite clearance rates. When comparing the three infection experiments, we identified different relationships of parasite clearance with dose and different maximum parasite clearance rates. In Plasmodium berghei-NMRI mouse infections, we estimated a maximum parasite clearance rate of 0.2 (1/h); in Plasmodium falciparum-SCID mouse infections, 0.05 (1/h); and in human volunteer infection studies with P. falciparum, we found a maximum parasite clearance rate of 0.12 (1/h) and 0.18 (1/h) after treatment with OZ439 and MMV048, respectively. Sensitivity analysis revealed that host-parasite driven processes account for up to 25% of variance in parasite clearance for medium-high doses of antimalarials. Although there are limitations in translating parasite clearance rates across these experiments, they provide insight into characterizing key parameters of drug action and dose response and assist in decision-making regarding dosage for further drug development.
Project description:Emerging drug resistance and high-attrition rates in early and late stage drug development necessitate accelerated development of antimalarial compounds. However, systematic and meaningful translation of drug efficacy and host-parasite dynamics between preclinical testing stages is missing. We developed an ensemble of mathematical within-host parasite growth and antimalarial action models, fitted to extensive data from four antimalarials with different modes of action, to assess host-parasite interactions in two preclinical drug testing systems of murine parasite P. berghei in mice, and human parasite P. falciparum in immune-deficient mice. We find properties of the host-parasite system, namely resource availability, parasite maturation and virulence, drive P. berghei dynamics and drug efficacy, whereas experimental constraints primarily influence P. falciparum infection and drug efficacy. Furthermore, uninvestigated parasite behavior such as dormancy influences parasite recrudescence following non-curative treatment and requires further investigation. Taken together, host-parasite interactions should be considered for meaningful translation of pharmacodynamic properties between murine systems and for predicting human efficacious treatment.
Project description:Src homology 2 (SH2) domain-containing phosphatase 2 (SHP2) has important cellular functions in mediating signal transduction downstream of receptor tyrosine kinases and immune cell receptors. In T cells, SHP2 is a key regulator of signalling pathways downstream of the checkpoint receptor programmed cell death protein 1 (PD-1) that suppresses T cell activation, and of the T cell receptor (TCR) that promotes T cell activation. SHP2 contains two SH2 domains: the N-SH2 and C-SH2 domains. Here, we describe a new approach for the chemical targeting of SHP2 by developing a peptide inhibitor, containing a non-hydrolysable phosphotyrosine (pTyr) mimetic, which selectively binds to the C-SH2 domain of SHP2. We found that incorporation of the pTyr mimetic L-O-malonyltyrosine (L-OMT) displayed robust binding affinity to the C-SH2 domain, while the widely used pTyr mimetic phosphonodifluoromethyl phenylalanine (F2Pmp) abolished binding, showing that the use of pTyr mimetics for SH2 domains is case dependent. Our C-SH2 inhibitor peptide (CSIP) impedes SHP2 activation and inhibits SHP2 phosphatase activity in vitro. CSIP is stable, cell permeable and non-cytotoxic in a model T cell line (Jurkat), in which it displays cellular activity in modulating T cell activation. As such, CSIP is a powerful chemical tool to study SHP2, in particular the role of its C-SH2 domain, in cellular contexts. CSIP enriches the toolbox of inhibitors with different modes of action to study SHP2.
Project description:BackgroundInfantile hemangioma (IH) is the most common tumor among infants, but the exact pathogenesis of IH is largely unknown. Our previous study revealed that glucose metabolism may play an important role in the pathogenesis of IH and that the inhibition of the glycolytic key enzyme phosphofructokinase-1 suppresses angiogenesis in IH. 6-Phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) is a metabolic enzyme that converts fructose-6-bisphosphate to fructose-2,6-bisphosphate (F-2,6-BP), which is the most potent allosteric activator of the rate-limiting enzyme phosphofructokinase-1. This study was performed to explore the role of PFKFB3 in IH.MethodsMicroarray analysis was performed to screen the differentially expressed genes (DEGs) between proliferating and involuting IH tissues. PFKFB3 expression was examined by western blot and immunohistochemistry analyses. Cell migration, apoptosis and tube formation were analyzed. Metabolic analyses were performed to investigate the effect of PFKFB3 inhibition by PFK15. Mouse models were established to examine the effect of PFKFB3 inhibition in vivo.ResultsPFKFB3 was identified as one of the most significant DEGs and was more highly expressed in proliferating IH tissues and hemangioma-derived endothelial cells (HemECs) than in involuting IH tissues and human umbilical vein endothelial cells, respectively. PFKFB3 inhibition by PFK15 suppressed HemEC glucose metabolism mainly by affecting glycolytic metabolite metabolism and decreasing the glycolytic flux. Moreover, PFK15 inhibited HemEC angiogenesis and migration and induced apoptosis via activation of the apoptosis pathway. Treatment with the combination of PFK15 with propranolol had a synergistic inhibitory effect on HemECs. Moreover, PFKFB3 knockdown markedly suppressed HemEC angiogenesis. Mechanistically, inhibition of PFKFB3 suppressed the PI3K-Akt signaling pathway and induced apoptotic cell death. More importantly, the suppression of PFKFB3 by PFK15 or shPFKFB3 led to markedly reduced tumor growth in vivo.ConclusionsOur findings suggest that PFKFB3 inhibition can suppress IH angiogenesis and induce apoptosis. Thus, targeting PFKFB3 may be a novel therapeutic strategy for IH.
Project description:The prolyl-tRNA synthetase (PRS) is an essential enzyme for protein translation and a validated target against malaria parasite. We describe five ATP mimetics (L95, L96, L97, L35, and L36) against PRS, exhibiting enhanced thermal stabilities in co-operativity with L-proline. L35 displays the highest thermal stability akin to halofuginone, an established inhibitor of Plasmodium falciparum PRS. Four compounds exhibit nanomolar inhibitory potency against PRS. L35 exhibits the highest potency of ∼1.6 nM against asexual-blood-stage (ABS) and ∼100-fold (effective concentration [EC50]) selectivity for the parasite. The macromolecular structures of PfPRS with L95 and L97 in complex with L-pro reveal their binding modes and catalytic site malleability. Arg401 of PfPRS oscillates between two rotameric configurations when in complex with L95, whereas it is locked in one of the configurations due to the larger size of L97. Harnessing such specific and selective chemical features holds significant promise for designing potential inhibitors and expediting drug development efforts.
Project description:Glucose is an essential nutrient for Plasmodium falciparum and robust glycolytic activity is indicative of viable parasites. Using NMR spectroscopy, we show that P. falciparum infected erythrocytes consume ~20 times more glucose, and trophozoites metabolize ~6 times more glucose than ring stage parasites. The glycolytic activity, and hence parasite viability, can be measured within a period of 2 h to 5 h, using this method. This facilitates antimalarial bioactivity screening on ring and trophozoite stage parasites, exclusively. We demonstrate this using potent and mechanistically distinct antimalarial compounds such as chloroquine, atovaquone, cladosporin, DDD107498 and artemisinin. Our findings indicate that ring stage parasites are inherently more tolerant to antimalarial inhibitors, a feature which may facilitate emergence of drug resistance. Thus, there is a need to discover novel antimalarial compounds, which are potent and fast acting against ring stage parasites. The NMR method reported here can facilitate the identification of such molecules.
Project description:The emergence of Plasmodium falciparum resistant to frontline therapeutics has prompted efforts to identify and validate agents with novel mechanisms of action. MEPicides represent a new class of antimalarials that inhibit enzymes of the methylerythritol phosphate (MEP) pathway of isoprenoid biosynthesis, including the clinically validated target, deoxyxylulose phosphate reductoisomerase (Dxr). Here we describe RCB-185, a lipophilic prodrug with nanomolar activity against asexual parasites. Growth of P. falciparum treated with RCB-185 was rescued by isoprenoid precursor supplementation, and treatment substantially reduced metabolite levels downstream of the Dxr enzyme. In addition, parasites that produced higher levels of the Dxr substrate were resistant to RCB-185. Notably, environmental isolates resistant to current therapies remained sensitive to RCB-185, the compound effectively treated sexually-committed parasites, and was both safe and efficacious in malaria-infected mice. Collectively, our data demonstrate that RCB-185 potently and selectively inhibits Dxr in P. falciparum, and represents a promising lead compound for further drug development.