Biology subjects

Lopes, C. D.

Publications and source records attributed to Lopes, C. D..

3 recordsLinked to original sources

bioRxiv2019

Mapping the S1 and S1 subsites of cysteine proteases with new dipeptidyl nitrile inhibitors as trypanocidal agents

The cysteine protease cruzipain is considered to be a validated target for therapeutic intervention in the treatment of Chagas disease. A series of 26 new compounds waswere designed, synthesized, and tested against the recombinant cruzain (Cz) to map its S1/S1' subsites. The same series was evaluated on a panel of four human cysteine proteases (CatB, CatK, CatL, CatS) and Leishmania mexicana CPB, which is a potential target for the treatment of cutaneous leishmaniasis. The synthesized compounds are dipeptidyl nitriles designed based on the most promising combinations of different moieties in P1 (ten), P2 (six), and P3 (four different building blocks). Eight compounds exhibited a Ki smaller than 20.0 nM for Cz, whereas three compounds met these criteria for LmCPB. The three inhibitors had an EC50 value of ca. 4 M, thus being equipotent to benznidazole according to the anti-trypanosomal effects. Our mapping approach and the respective structure-activity relationships provide insights into the specific ligand-target interactions for therapeutically relevant cysteine proteases.\n\nAuthor SummaryDespite many achievements in identifying novel agents for the treatment of tropical and neglected diseases, further research continues to be of fundamental importance. Our research groups have been using the cruzipain cysteine protease in its recombinant form, cruzain (Cz), to identify new trypanocidal agents. Considering the possible interchangeability with other cysteine proteases, the same series of dipeptidyl nitriles was tested in Leishmania mexicana LmCPB. Other potential targets for such inhibitors are human cysteine cathepsins, which are involved in different disease states. Thus, the inhibitors were also tested against cathepsins B, L, K, and S. Our results demonstrate that inhibition of these cysteine proteases can be achieved by appropriate structural modifications of dipeptidyl nitriles. It was also possible to identify trypanocidal agents, equipotent to benznidazole, the current drug of choice used for the treatment of Chagas disease.

biochemistry↗

bioRxiv2018

Organometallic gold(III) Cl (L1 = SNS-donating thiosemicarbazone) complex protects mice against acute T. cruzi infection

Chagas disease remains a serious public health concern with unsatisfactory treatment outcomes due to strain-specific drug resistance and various side effects. To identify new therapeutic drugs against Trypanosoma cruzi, we evaluated both the in vitro and in vivo activity of the organometallic gold(III) complex [Au(Hdamp)(L14)]Cl (L1 = SNS- donating thiosemicarbazone), which was denoted 4-Cl. Our results demonstrated that 4- Cl was more effective than benznidazole (Bz) in eliminating both the extracellular trypomastigote and the intracellular amastigote forms of the parasite without cytotoxic effects on mammalian cells. In very-low-dose in vivo assays, 4-Cl reduced parasitaemia and tissue parasitism in addition to protecting the liver and heart from tissue damage. All these changes resulted in the survival of 100% of the mice treated with 4-Cl during the acute phase. We hypothesised that 4-Cl can act directly on the parasite and may participate in the modulation of IFN-{gamma} production at the acute stage of the disease. Molecular docking simulations showed that the compound may interact with cruzain, a thiol protease considered a possible antiparasitic drug target, primarily by hydrophobic interactions. These analyses predicted that the Cys25 residue in the cruzain binding site is approximately 3.0 [A] away from the S and Au atoms of the gold compound, which could suggest formation of a possible covalent bond between cruzain and the inhibitor. Overall, we confirmed the potential of 4-Cl as a new candidate for Chagas disease treatment.

pharmacology and toxicology↗

bioRxiv2017

Toxoplasma gondii microneme proteins 1 and 4 bind to Toll-like receptors 2 and 4 N-glycans triggering innate immune response

Infection of host cells by Toxoplasma gondii is an active process, which is regulated by secretion of microneme (MICs) and rhoptry proteins (ROPs and RONs) from specialized organelles in the apical pole of the parasite. MIC1, MIC4 and MIC6 assemble into an adhesin complex, secreted on the parasite surface and function to promote infection competency. MIC1 and MIC4 are known to bind terminal sialic acid residues and galactose residues, respectively and to induce IL-12 production from splenocytes. Here we show that rMIC1- and rMIC4-stimulated dendritic cells and macrophages to produce proinflammatory cytokines, and they do so by engaging TLR2 and TLR4. This process depends on sugar recognition, since point mutations in the carbohydrate-recognition domains (CRD) of rMIC1 and rMIC4 inhibit innate immune cells activation. HEK cells transfected with TLR2 glycomutants were selectively unresponsive to MICs. Following in vitro infection, parasites lacking MIC1 or MIC4, as well as expressing MIC proteins with point mutations in their CRD, failed to induce wild-type (WT) levels of IL-12 secretion by innate immune cells. However, only MIC1 was shown to impact systemic levels of IL-12 and IFN-{gamma} in vivo. Together, our data show that MIC1 and MIC4 interact physically with TLR2 and TLR4 N-glycans to trigger IL-12 responses, and MIC1 is playing a significant role in vivo by altering T. gondii infection competency and murine pathogenesis.\n\nAUTHOR SUMMARYToxoplasmosis is caused by the protozoan Toxoplasma gondii, belonging to the Apicomplexa phylum. This phylum comprises important parasites able to infect a broad diversity of animals, including humans. A particularity of T. gondii is its ability to invade virtually any nucleated cell of all warm-blooded animals through an active process, which depends on the secretion of adhesin proteins. These proteins are discharged by specialized organelles localized in the parasite apical region, and termed micronemes and rhoptries. We show in this study that two microneme proteins from T. gondii utilize their adhesion activity to stimulate innate immunity. These microneme proteins, denoted MIC1 and MIC4, recognize specific sugars on receptors expressed on the surface of mammalian immune cells. This binding activates these innate immune cells to secrete cytokines, which promotes efficient host defense mechanisms against the parasite and regulate their pathogenesis. This activity promotes a chronic infection by controlling parasite replication during acute infection.

immunology↗