The economic burden of Lyme disease and the cost-effectiveness of Lyme disease interventions: A scoping review.

INTRODUCTION: While Lyme disease (LD) is mostly treatable, misdiagnosed or untreated LD can result in debilitating sequelae and excessive healthcare usage. The objective of this review was to characterize the body of literature on the economic burden of Lyme disease (LD) and the cost-effectiveness of LD interventions, such as antibiotic treatment and vaccination. METHODS: We followed Joanna Briggs Institute scoping review methodologies. We systematically searched terms related to LD, economic evaluations, costs, and cost-effectiveness in Medline, Embase, PsycInfo, Cochrane Library, and the grey literature up to November 2017. We included primary economic evaluations conducted in North America and Europe, reporting LD-related costs or cost-effectiveness of human interventions. Two reviewers screened articles and charted data independently. Costs were standardized to 2017 United States dollars (USD). RESULTS: We screened 923 articles, and included 10 cost-effectiveness analyses (CEA) and 11 cost analyses (CA). Three CEAs concluded LD vaccination was likely cost-effective only in endemic areas (probability of infection ≥1%). However, LD vaccination is not currently available as an intervention in the US or Europe. Six studies assessed economic burden from a societal perspective and estimated significant annual national economic impact of: 735,550 USD for Scotland (0.14 USD per capita, population = 5.40M), 142,562 USD in Sweden (0.014 USD per capita, 9.96M), 40.88M USD in Germany (0.51 USD per capita, 80.59M), 23.12M USD in the Netherlands (1.36 USD per capita, 17.08M), and up to 786M USD in the US (2.41 USD per capita, 326.63M). CONCLUSIONS: Lyme disease imposes an economic burden that could be considered significant in the US and other developed countries to justify further research efforts in disease control and management. Societal costs for Lyme disease can be equally impactful as healthcare costs, but are not fully understood. Economic literature from countries with historically high incidence rates or increasing rates of Lyme disease are limited, and can be useful for future justification of resource allocation.

A Rhodnius prolixus Insulin Receptor and Its Conserved Intracellular Signaling Pathway and Regulation of Metabolism.

The insulin signaling pathway is a modulator of metabolism in insects and can regulate functions associated with growth and development, as well as lipid and carbohydrate balance. We have previously reported the presence of an insulin-like peptide and an insulin-like growth factor in Rhodnius prolixus, which are involved in the homeostasis of lipids and carbohydrates in post-feeding and non-feeding periods. In the present study, we have characterized the first insulin receptor (IR) to be discovered in R. prolixus, Rhopr-IR, and investigated its intracellular signaling cascade and its role in nutrient control. We identified a candidate protein sequence within R. prolixus putative peptidome and predicted its conserved features using bioinformatics. Tissue-specific expression analyses indicated that the Rhopr-IR transcript is differentially-expressed in all tissues tested, with the highest values observed in the central nervous system (CNS). Treatment of insects with the IR kinase activator BpV(phen), glucose, or porcine insulin resulted in the activation of protein phosphorylation in the fat body, and stimulated the phosphorylation of protein kinase Akt, an evolutionarily conserved key regulator of the intracellular insulin signaling cascade. We also observed activation of Akt and phosphorylation of its downstream targets glycogen synthase kinase 3 ß (GSK3ß) and the transcription factor FOXO for several days following a blood meal. We used dsRNA to knockdown transcript expression and examined the resulting effects on metabolism and intracellular signaling. Furthermore, knockdown of the Rhopr-IR transcript increased lipid levels in the hemolymph, while reducing lipid content in the fat body. Interestingly, the levels of carbohydrates in the hemolymph and in the fat body did not show any alterations. The activation of Akt and phosphorylation of FOXO were also reduced in knockdown insects, while the phosphorylation pattern of GSK3ß did not change. Our results support the identification of the first IR in R. prolixus and suggest that Rhopr-IR signaling is involved in hemolymph nutrient homeostasis and fat body storage both in post-feeding and in non-feeding stages. These metabolic effects are likely regulated by the activation of Akt and downstream cascades similar to mammalian insulin signaling pathways.

Regulating the Master Regulator: Controlling Ubiquitination by Thinking Outside the Active Site.

The labeling of proteins with ubiquitin/ubiquitin-like (Ubl) proteins is crucial for several physiological processes and in the onset of various diseases. Recently, targeting ubiquitin protein labeling has shifted toward the use of allosteric mechanisms over classical activity-based approaches. Allosteric enzyme regulation offers the potential for greater selectivity and has demonstrated less susceptibility to acquired resistance often associated with active site inhibitors. Furthermore, the isoform diversity among E1 activating, E2 conjugating, E3 ligase, and deubiquitinating (DUB) enzymes offers an ideal platform for modulating activity via allostery. Herein, we have reviewed allosteric inhibitors of the ubiquitin E1-E2-E3 and DUB enzymatic cascade developed over the past decade with a focus on their mechanisms of action. We have highlighted the advantages as well as the challenges associated with designing allosteric modulators of the ubiquitin labeling machinery, and the future promise in targeting these systems using allosteric approaches.

A selective inhibitor of the UFM1-activating enzyme, UBA5.

Protein conjugation with ubiquitin and ubiquitin-like small molecules, such as UFM1, is important for promoting cancer cell survival and proliferation. Herein, the development of the first selective micromolar inhibitor of the UBA5 E1 enzyme that initiates UFM1 protein conjugation is described. This organometallic inhibitor incorporates adenosine and zinc(II)cyclen within its core scaffold and inhibits UBA5 noncompetitively and selectively over other E1 enzymes and a panel of human kinases. Furthermore, this compound selectively impedes the cellular proliferation (above 50µM) of cancer cells containing higher levels of UBA5. This inhibitor may be used to further probe the intracellular role of the UFM1 pathway in disease progression.

Mutations in UBA3 confer resistance to the NEDD8-activating enzyme inhibitor MLN4924 in human leukemic cells.

The NEDD8-activating enzyme (NAE) initiates neddylation, the cascade of post-translational NEDD8 conjugation onto target proteins. MLN4924, a selective NAE inhibitor, has displayed preclinical anti-tumor activity in vitro and in vivo, and promising clinical activity has been reported in patients with refractory hematologic malignancies. Here, we sought to understand the mechanisms of resistance to MLN4924. K562 and U937 leukemia cells were exposed over a 6 month period to MLN4924 and populations of resistant cells (R-K562(MLN), R-U937(MLN)) were selected. R-K562(MLN) and R-U937(MLN) cells contain I310N and Y352H mutations in the NAE catalytic subunit UBA3, respectively. Biochemical analyses indicate that these mutations increase the enzyme's affinity for ATP while decreasing its affinity for NEDD8. These mutations effectively contribute to decreased MLN4924 potency in vitro while providing for sufficient NAE function for leukemia cell survival. Finally, R-K562(MLN) cells showed cross-resistance to other NAE-selective inhibitors, but remained sensitive to a pan-E1 (activating enzyme) inhibitor. Thus, our work provides insight into mechanisms of MLN4924 resistance to facilitate the development of more effective second-generation NAE inhibitors.

Exploring a new frontier in cancer treatment: targeting the ubiquitin and ubiquitin-like activating enzymes.

The labeling of proteins with small ubiquitin (Ub) and ubiquitin-like (Ubl) modifiers regulates a plethora of activities within the cell, such as protein recycling, cell cycle modifications, and protein translocation. These processes are often overactive in diseased cells, leading to unregulated cell growth and disease progression. Therefore, in systems where Ub/Ubl protein labeling is dysregulated, the development of drugs to selectively and potently disrupt Ub/Ubl protein labeling offers a targeted molecular approach for sensitizing these diseased cells. This Perspective outlines the progress that has been made in the context of inhibitor development for targeting Ub/Ubl pathways.

Targeting the ubiquitin E1 as a novel anti-cancer strategy.

The proteasomal pathway of protein degradation involves two discrete steps: ubiquitination and degradation. Blocking protein degradation by inhibiting the proteasome has well described biologic effects and proteasome inhibitors are approved for the treatment of multiple myeloma and mantle cell lymphoma. In contrast, the biological effects and potential therapeutic utility of inhibiting the ubiquitination cascade and the initiating enzyme UBA1 are less well understood. UBA1 is the initial enzyme in the ubiquitination cascade and initiates the transfer of ubiquitin molecules to target proteins where they are degraded by the proteasome. Here, we review the biological effects of UBA1 inhibition and discuss UBA1 inhibitors as potential anti-cancer agents. Similar to proteasome inhibition, blocking UBA1 elicits an unfolded protein response and induces cell death in malignant cells over normal cells. Chemical UBA1 inhibitors have been developed that target different regions of the enzyme and inhibit its function through different mechanisms. These molecules are useful tools to understand the biology of UBA1 and highlight the potential of inhibiting this target for the treatment of malignancy.

The regulation of cardiac activity by nitric oxide (NO) in the Vietnamese stick insect, Baculum extradentatum.

This study examines the role of the unconventional gaseous signaling molecule nitric oxide (NO) on the regulation of heart rate in the Vietnamese stick insect, Baculum extradentatum. Using nicotinamide dinucleotide hydrogen phosphate (NADPH)-diaphorase histochemistry, as well as immunohistochemistry and Western blotting with an antibody against NO synthetase (NOS), we identified the presence of NOS in hemocytes present throughout the lumen of the dorsal vessel. We propose that NO is delivered to heart muscle tissue via hemocytes circulating within the hemolymph. In the present study, stimulation of NO levels by the application of the NO donor MAHMA-NONOate and l-arginine led to a dose-dependent decrease in heart rate. Treatment of tissues with the NOS inhibitor, L-NAME, in equimolar concentrations with l-arginine, led to a recovery of heart rate, without modifying heart rate on its own. Finally guanosine 3',5'-cyclic monophosphate (cGMP) analog, 8-bromo-cGMP, elicited similar inhibitory effects on stick insect heart rate as did the guanylate cyclase activator, YC-1, and the phosphodiesterase inhibitor, dipyridamole, indicating that cGMP is most likely the second messenger in the stick insect NO signaling pathway. Contrary to the cardioexcitatory effect of NO on other insect hearts, we have found that NO inhibits stick insect heart rate independently from any nervous system input, in a similar inhibitory fashion as that of vertebrate hearts.

Effects of crustacean cardioactive peptide on the hearts of two Orthopteran insects, and the demonstration of a Frank-Starling-like effect.

Like vertebrate cardiovascular systems, the dorsal vessel of the Orthopteran insects Baculum extradentatum and Locusta migratoria is under myogenic as well as neural control, through the action of neurotransmitters, neuromodulators and neurohormones. It was previously shown that the excitatory neuropeptide, crustacean cardioactive peptide (CCAP), triggers an increase in heart rate in B. extradentatum, and CCAP-like immunoreactivity is present in the innervation to the heart in many insects. In the present study, CCAP resulted in a dose-dependent increase in heart rate and hemolymph flow velocity, or cardiac output, in B. extradentatum. In contrast, CCAP led to a significant increase in stroke volume and cardiac output in L. migratoria without modifying heart rate or aortic contraction frequency. Hemolymph flow through the excurrent ostia of L. migratoria, small openings or valves on the posterior aorta and anterior heart, was inhibited with increasing concentrations of CCAP, with complete inhibition seen at 10(-7) M CCAP. In the locust, CCAP increases the volume of hemolymph in the dorsal vessel by the synchronous closing of the excurrent ostia, resulting in more forceful heart contractions and increased stroke volume and cardiac output, without modifying heart rate through a physiological mechanism analogous to the Frank-Starling mechanism in vertebrates. Therefore, crustacean cardioactive peptide alters the contractile properties of cardiac tissue in both B. extradentatum and L. migratoria, allowing for an increase in blood flow and circulation.

Identification of NAE Inhibitors Exhibiting Potent Activity in Leukemia Cells: Exploring the Structural Determinants of NAE Specificity.

MLN4924 is a selective inhibitor of the NEDD8-activating enzyme (NAE) and has advanced into clinical trials for the treatment of both solid and hematological malignancies. In contrast, the structurally similar compound 1 (developed by Millennium: The Takeda Oncology Company) is a pan inhibitor of the E1 enzymes NAE, ubiquitin activating enzyme (UAE), and SUMO-activating enzyme (SAE) and is currently viewed as unsuitable for clinical use given its broad spectrum of E1 inhibition. Here, we sought to understand the determinants of NAE selectivity. A series of compound 1 analogues were synthesized through iterative functionalization of the purine C6 position and evaluated for NAE specificity. Optimal NAE specificity was achieved through substitution with primary N-alkyl groups, while bulky or secondary N-alkyl substituents were poorly tolerated. When assessed in vitro, inhibitors reduced the growth and viability of malignant K562 leukemia cells. Through this study, we have successfully identified a series of sub-10 nM NAE-specific inhibitors and thereby highlighted the functionalities that promote NAE selectivity.