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Tuberculosis (TB) is one of the main causes of death from a single pathological agent, Mycobacterium tuberculosis (Mtb). In addition, the emergence of drug-resistant TB strains has exacerbated even further the treatment outcome of TB patients. It is thus needed the search for new therapeutic strategies to improve the current treatment and to circumvent the resistance mechanisms of Mtb. The shikimate kinase (SK) is the fifth enzyme of the shikimate pathway, which is essential for the survival of Mtb. The shikimate pathway is absent in humans, thereby indicating SK as an attractive target for the development of anti-TB drugs. In this work, a combination of in silico and in vitro techniques was used to identify potential inhibitors for SK from Mtb (MtSK). All compounds of our in-house database (Centro de Pesquisas em Biologia Molecular e Funcional, CPBMF) were submitted to in silico toxicity analysis to evaluate the risk of hepatotoxicity. Docking experiments were performed to identify the potential inhibitors of MtSK according to the predicted binding energy. In vitro inhibitory activity of MtSK-catalyzed chemical reaction at a single compound concentration was assessed. Minimum inhibitory concentration values for in vitro growth of pan-sensitive Mtb H37Rv strain were also determined. The mixed approach implemented in this work was able to identify five compounds that inhibit both MtSK and the in vitro growth of Mtb.

Herein a series of 4-aminoquinolines were synthesized in an attempt to optimize and study the structural features related to LABIO-17 biological activity, a Mycobacterium tuberculosis NADH-dependent enoyl-acyl carrier protein reductase (MtInhA) inhibitor previously identified by a virtual-ligand-screening approach. Structure-activity relationships led to novel submicromolar inhibitors of MtInhA and potent antitubercular agents. The lead compound is 87-fold more potent as enzymatic inhibitors and 32-fold more potent against M. tuberculosis H37Rv strain in comparison with LABIO-17. These molecules were also active against multidrug-resistant strains, devoid of apparent toxicity to mammalian cells and showed favorable in vitro ADME profiles. Additionally, these compounds were active in an intracellular model of tuberculosis (TB) infection, showed no genotoxicity signals, satisfactory absorption parameters and absence of in vivo acute toxicity. Finally, treatment with selected 4-aminoquinoline for two weeks produced bacteriostatic effect in a murine model of TB. Taken together, these findings indicate that this chemical class may furnish candidates for the future development of drug-sensitive and drug-resistant tuberculosis treatments.

Overexpressed human thymidine phosphorylase (hTP) has been associated with cancer aggressiveness and poor prognosis by triggering proangiogenic and antiapoptotic signaling. Designed as transition-state analogues by mimicking the oxacarbenium ion, novel pyrimidine-2,4-diones were synthesized and evaluated as inhibitors of hTP activity. The most potent compound (8g) inhibited hTP in the submicromolar range with a noncompetitive inhibition mode with both thymidine and inorganic phosphate substrates. Furthermore, compound 8g was devoid of apparent toxicity to a panel of mammalian cells, showed no genotoxicity signals, and had low probability of drug-drug interactions and moderate in vitro metabolic rates. Finally, treatment with 8g (50 mg/(kg day)) for 2 weeks (5 days/week) significantly reduced tumor growth using an in vivo glioblastoma model. To the best of our knowledge, this active compound is the most potent in vitro hTP inhibitor with a kinetic profile that cannot be reversed by the accumulation of any enzyme substrates.

The epidemiological importance of bacteria from the genusMycobacteriumis indisputable and the necessity to find new molecules that can inhibit their growth is urgent. The shikimate pathway, required for the synthesis of important metabolites in bacteria, represents a target for inhibitors ofMycobacterium tuberculosisgrowth. ThearoA-encoded 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) enzyme catalyzes the sixth step of the shikimate pathway. In this study, we combined gene knockout, gene knockdown and kinetic assays to evaluatearoAgene essentiality and the vulnerability of its protein product, EPSPS synthase fromMycobacterium smegmatis(MsEPSPS), under different nutritional conditions. We demonstrate by an allelic exchange-based gene knockout approach the essentiality ofMsEPSPS under rich and poor nutritional conditions. By performing gene complementation experiments with wild-type (WT) and point mutant versions ofaroAgene, together with kinetic assays using WT and mutant recombinant proteins, we show thataroAgene essentiality depends onMsEPSPS activity. To evaluateMsEPSPS vulnerability, we performed gene knockdown experiments using the Clustered Regularly Interspaced Short Palindromic Repeats interference (CRISPRi) system. The experiments were performed in both rich and defined (poor) media, using three different repression forces foraroAgene. We only observed growth impairment when bacteria were grown in defined medium without supplementation of aromatic amino acids, thereby indicating thatMsEPSPS vulnerability depends on the environment conditions.ImportanceWe evaluated both gene essentiality and target vulnerability of the enzyme that catalyzes the sixth step of the shikimate pathway, thearoA-encoded 5-enolpyruvylshikimate-3-phosphate synthase fromMycobacterium smegmatis(MsEPSPS). Combining gene knockout experiments and kinetic assays, we established a causal link betweenaroAgene essentiality and the biological function of EPSPS protein, which we advocate is an indispensable step for target validation. Moreover, we characterizedMsEPSPS vulnerability under different nutritional conditions and found it is a vulnerable target only whenM. smegmatisis grown under poor nutritional conditions without supplementation with aromatic amino acids. Based on our findings, we suggest that gene essentiality information should be obtained from gene knockout experiments and not knockdown approaches, as even low levels of a protein after gene silencing can lead to a different growth phenotype when compared to that under its complete absence, as was the case witharoAandMsEPSPS in our study.

Human thymidine phosphorylase (hTP) is overexpressed in several solid tumors and is commonly associated with aggressiveness and unfavorable prognosis. 6-(((1,3-Dihydroxypropan-2-yl)amino)methyl)-5-iodopyrimidine-2,4(1H,3H)-dione (CPBMF-223) is a noncompetitive hTP inhibitor, which has been described as a tumor angiogenesis inhibitor. The present study investigated the effects of CPBMF-223 in a xenograft tumor induced by human colorectal carcinoma cells (HCT-116). Additionally, CPBMF-223 capacity to reduce cell migration, its toxicological profile, and pharmacokinetic characteristics, were also evaluated. The intraperitoneal treatment with CPBMF-223 markedly prevented the relative tumor growth with an efficacy similar to that observed for 5-fluorouracil. Interestingly, number of vessels were significantly decreased in the treated groups. Moreover, CPBMF-223 significantly reduced the migration of cell line HCT-116. In the Ames assay and in an acute oral toxicity test, the molecule did not alter any evaluated parameter. Using the zebrafish toxicity model, cardiac and locomotor parameters were slightly changed. Regarding the pharmacokinetics profile, CPBMF-223 showed clearance of 9.42 L/h/kg after intravenous administration, oral bioavailability of 13.5%, and a half-life of 0.75 h. Our findings shed new light on the role of hTP in colorectal cancer induced by HCT-116 cell in mice, pointing out CPBMF-223 as, hopefully, a promising drug candidate.

Adenylosuccinate lyase (ASL) is involved in both de novo and salvage pathways of purine biosynthesis. ASL belongs to the argininosuccinate lyase/fumarase C superfamily of enzymes which share a general acid–base catalytic mechanism with β-elimination of fumarate as the common product. Cloning, expression, and a method to obtain homogeneous recombinant ASL from Leishmania braziliensis (LbASL) are described. Mass spectrometry analysis of recombinant LbASL, oligomeric state determination and multiple sequence alignment are presented. Steady-state kinetics of LbASL showed a Michaelis–Menten pattern. Isothermal titration calorimetry binding assays suggested that LbASL follows a Uni-Bi ordered kinetic mechanism, in which release of fumarate is followed by AMP to yield free enzyme. Initial velocity data for the reverse reaction and the Haldane relationship allowed calculation of an unfavorable equilibrium constant for the LbASL-catalyzed chemical reaction. The activation energy and thermodynamic activation parameters were estimated. Solvent kinetic isotope effects V/K and V suggest a modest contribution of solvent proton transference during the rate-limiting step of the reaction. Proton inventory data show that the modest normal effect on V arises from a single protonic site, and the transition state fractionation factor value of 0.74 suggests participation of solvent proton transfer in transition-state vibrations perpendicular to the reaction coordinate. pH-rate profiles for kcat and kcat/KM suggested amino acid residues involved in, respectively, catalysis and substrate binding. A model of LbASL was built to provide a structural basis for the experimental data. A better understanding of the mode of action of LbASL is useful for the rational design of antileishmaniasis agents.

Mice transplanted with human cord blood-derived hematopoietic stem cells (HSCs) became a powerful experimental tool for studying the heterogeneity of human immune reconstitution and immune responses in vivo. Yet, analyses of human T cell maturation in humanized models have been hampered by an overall low immune reactivity and lack of methods to define predictive markers of responsiveness. Long-lived human lentiviral induced dendritic cells expressing the cytomegalovirus pp65 protein (iDCpp65) promoted the development of pp65-specific human CD8+ T cell responses in NOD.Cg-Rag1 tm1Mom -Il2rγ tm1Wj humanized mice through the presentation of immune-dominant antigenic epitopes (signal 1), expression of co-stimulatory molecules (signal 2), and inflammatory cytokines (signal 3). We exploited this validated system to evaluate the effects of mouse sex in the dynamics of T cell homing and maturation status in thymus, blood, bone marrow, spleen, and lymph nodes. Statistical analyses of cell relative frequencies and absolute numbers demonstrated higher CD8+ memory T cell reactivity in spleen and lymph nodes of immunized female mice. In order to understand to which extent the multidimensional relation between organ-specific markers predicted the immunization status, the immunophenotypic profiles of individual mice were used to train an artificial neural network designed to discriminate immunized and non-immunized mice. The highest accuracy of immune reactivity prediction could be obtained from lymph node markers of female mice (77.3%). Principal component analyses further identified clusters of markers best suited to describe the heterogeneity of immunization responses in vivo. A correlation analysis of these markers reflected a tissue-specific impact of immunization. This allowed for an organ-resolved characterization of the immunization status of individual mice based on the identified set of markers. This new modality of multidimensional analyses can be used as a framework for defining minimal but predictive signatures of human immune responses in mice and suggests critical markers to characterize responses to immunization after HSC transplantation.

Effective immunization of patients shortly after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an unmet clinical need due to delayed de novo development of T and B cells. We demonstrated a recombinant, donor-derived cell vaccine against cytomegalovirus that can be easily manufactured, cryopreserved and, upon thaw and administration, turn themselves into highly-viable dendritic cells (DCs). The cell source consisted of monocytes from peripheral blood or cord blood (CB), transduced with an integrase-defective lentiviral vector (IDLV, co-expressing GM-CSF, IFN-α and the cytomegalovirus antigen pp65). The pharmacodynamics of the frozen/thawed vaccine (“SmyleDCpp65”) was evaluated by immunization of NOD.Rag1–/–.IL2rγ–/– mice transplanted with human CD34+ CB stem cells. SmyleDCpp65 stimulated in vivo thymic and extrathymic expansion of human cytotoxic T cells (CTL) reactive against pp65, and high levels of human immunoglobulins and immune-stimulatory cytokines in plasma. Standardized production of the IDLV and SmyleDCpp65 was established using Good Manufacturing Practices (GMP). Analytical parameters for quality control demonstrated high recovery, uniformity, purity and viability of SmyleDCpp65 after thawing. Stimulation of autologous T cells by GMP-grade SmyleDCpp65 was validated. SmyleDCpp65 showed only residual and polyclonal IDLV integration, unbiased to protooncogenic hot-spots. These results underscore further developments of this individualized cell vaccine to accelerate immune reconstitution against cytomegalovirus after allo-HSCT.