RESUMO
Antibodies play a central role in the immune defense against SARS-CoV-2. Emerging evidence has shown that nonneutralizing antibodies are important for immune defense through Fc-mediated effector functions. Antibody subclass is known to affect downstream Fc function. However, whether the antibody subclass plays a role in anti-SARS-CoV-2 immunity remains unclear. Here, we subclass-switched eight human IgG1 anti-spike monoclonal antibodies (mAbs) to the IgG3 subclass by exchanging their constant domains. The IgG3 mAbs exhibited altered avidities to the spike protein and more potent Fc-mediated phagocytosis and complement activation than their IgG1 counterparts. Moreover, combining mAbs into oligoclonal cocktails led to enhanced Fc- and complement receptor-mediated phagocytosis, superior to even the most potent single IgG3 mAb when compared at equivalent concentrations. Finally, in an in vivo model, we show that opsonic mAbs of both subclasses can be protective against a SARS-CoV-2 infection, despite the antibodies being nonneutralizing. Our results suggest that opsonic IgG3 oligoclonal cocktails are a promising idea to explore for therapy against SARS-CoV-2, its emerging variants, and potentially other viruses.
Assuntos
COVID-19 , Imunoglobulina G , Humanos , Opsonização , SARS-CoV-2 , Fagocitose , Anticorpos Monoclonais/farmacologiaRESUMO
Chlamydia trachomatis is a strict intracellular bacterium that causes sexually transmitted infections and eye infections that can lead to life-long sequelae. Treatment options are limited to broad-spectrum antibiotics that disturb the commensal flora and contribute to selection of antibiotic-resistant bacteria. Hence, development of novel drugs that specifically target C. trachomatis would be beneficial. 2-pyridone amides are potent and specific inhibitors of Chlamydia infectivity. The first generation compound KSK120, inhibits the developmental cycle of Chlamydia resulting in reduced infectivity of progeny bacteria. Here, we show that the improved, highly potent second-generation 2-pyridone amide KSK213 allowed normal growth and development of C. trachomatis and the effect was only observable upon re-infection of new cells. Progeny elementary bodies (EBs) produced in the presence of KSK213 were unable to activate transcription of essential genes in early development and did not differentiate into the replicative form, the reticulate body (RB). The effect was specific to C. trachomatis since KSK213 was inactive in the closely related animal pathogen C. muridarum and in C. caviae The molecular target of KSK213 may thus be different in C. trachomatis or non-essential in C. muridarum and C. caviae Resistance to KSK213 was mediated by a combination of amino acid substitutions in both DEAD/DEAH RNA helicase and RNAse III, which may indicate inhibition of the transcriptional machinery as the mode of action. 2-pyridone amides provide a novel antibacterial strategy and starting points for development of highly specific drugs for C. trachomatis infections.
RESUMO
The host employs both cell-autonomous and system-level responses to limit pathogen replication in the initial stages of infection. Previously, we reported that the eukaryotic initiation factor 2α (eIF2α) kinases heme-regulated inhibitor (HRI) and protein kinase R (PKR) control distinct cellular and immune-related activities in response to diverse bacterial pathogens. Specifically for Listeria monocytogenes, there was reduced translocation of the pathogen to the cytosolic compartment in HRI-deficient cells and consequently reduced loading of pathogen-derived antigens on major histocompatibility complex class I (MHC-I) complexes. Here we show that Hri-/- mice, as well as wild-type mice treated with an HRI inhibitor, are more susceptible to listeriosis. In the first few hours of L. monocytogenes infection, there was much greater pathogen proliferation in the liver of Hri-/- mice than in the liver of Hri+/+ mice. Further, there was a rapid increase of serum interleukin-6 (IL-6) levels in Hri+/+ mice in the first few hours of infection whereas the increase in IL-6 levels in Hri-/- mice was notably delayed. Consistent with these in vivo findings, the rate of listeriolysin O (LLO)-dependent pathogen efflux from infected Hri-/- macrophages and fibroblasts was significantly higher than the rate seen with infected Hri+/+ cells. Treatment of cells with an eIF2α kinase activator enhanced both the HRI-dependent and PKR-dependent infection phenotypes, further indicating the pharmacologically malleability of this signaling pathway. Collectively, these results suggest that HRI mediates the cellular confinement and killing of virulent L. monocytogenes in addition to promoting a system-level cytokine response and that both are required to limit pathogen replication during the first few hours of infection.
Assuntos
Listeria monocytogenes/fisiologia , Listeriose/enzimologia , Proteínas Serina-Treonina Quinases/imunologia , Animais , Feminino , Humanos , Interleucina-6/genética , Interleucina-6/metabolismo , Listeria monocytogenes/genética , Listeriose/genética , Listeriose/imunologia , Listeriose/microbiologia , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação , Proteínas Serina-Treonina Quinases/genéticaRESUMO
The host-encoded Perforin-2 (encoded by the macrophage-expressed gene 1, Mpeg1), which possesses a pore-forming MACPF domain, reduces the viability of bacterial pathogens that reside within membrane-bound compartments. Here, it is shown that Perforin-2 also restricts the proliferation of the intracytosolic pathogen Listeria monocytogenes Within a few hours of systemic infection, the massive proliferation of L. monocytogenes in Perforin-2(-/-)mice leads to a rapid appearance of acute disease symptoms. We go on to show in cultured Perforin-2(-/-)cells that the vacuole-to-cytosol transitioning of L. monocytogenesis greatly accelerated. Unexpectedly, we found that in Perforin-2(-/-)macrophages,Listeria-containing vacuoles quickly (≤ 15 min) acidify, and that this was coincident with greater virulence gene expression, likely accounting for the more rapid translocation of L. monocytogenes to its replicative niche in the cytosol. This hypothesis was supported by our finding that aL. monocytogenes strain expressing virulence factors at a constitutively high level replicated equally well in Perforin-2(+/+)and Perforin-2(-/-)macrophages. Our findings suggest that the protective role of Perforin-2 against listeriosis is based on it limiting the intracellular replication of the pathogen. This cellular activity of Perforin-2 may derive from it regulating the acidification of Listeria-containing vacuoles, thereby depriving the pathogen of favorable intracellular conditions that promote its virulence gene activity.
Assuntos
Citosol/fisiologia , Listeria monocytogenes/fisiologia , Proteínas de Membrana/metabolismo , Proteínas Citotóxicas Formadoras de Poros/metabolismo , Vacúolos/fisiologia , Animais , Células Cultivadas , Citosol/microbiologia , Regulação da Expressão Gênica/fisiologia , Listeria monocytogenes/ultraestrutura , Listeriose/metabolismo , Listeriose/microbiologia , Proteínas de Membrana/genética , Camundongos , Proteínas Citotóxicas Formadoras de Poros/genética , Estrutura Terciária de ProteínaRESUMO
Chlamydia trachomatis replication takes place inside of a host cell, exclusively within a vacuole known as the inclusion. During an infection, the inclusion expands to accommodate the increasing numbers of C. trachomatis. However, whether inclusion expansion requires bacterial replication and/or de novo protein synthesis has not been previously investigated in detail. Therefore, using a chemical biology approach, we herein investigated C. trachomatis inclusion expansion under varying conditions in vitro. Under normal cell culture conditions, inclusion expansion correlated with C. trachomatis replication. When bacterial replication was inhibited using KSK120, an inhibitor that targets C. trachomatis glucose metabolism, inclusions expanded even in the absence of bacterial replication. In contrast, when bacterial protein synthesis was inhibited using chloramphenicol, expansion of inclusions was blocked. Together, these data suggest that de novo protein synthesis is necessary, whereas bacterial replication is dispensable for C. trachomatis inclusion expansion.
Assuntos
Chlamydia trachomatis/crescimento & desenvolvimento , Células Epiteliais/microbiologia , Vacúolos/microbiologia , Proteínas de Bactérias/biossíntese , Chlamydia trachomatis/genética , Chlamydia trachomatis/metabolismo , Citoplasma/microbiologia , Replicação do DNA , DNA Bacteriano/biossíntese , Células HeLa , HumanosRESUMO
Streptococcus pyogenes can cause invasive disease with high mortality despite adequate antibiotic treatments. To address this unmet need, we have previously generated an opsonic IgG1 monoclonal antibody, Ab25, targeting the bacterial M protein. Here, we engineer the IgG2-4 subclasses of Ab25. Despite having reduced binding, the IgG3 version promotes stronger phagocytosis of bacteria. Using atomic simulations, we show that IgG3's Fc tail has extensive movement in 3D space due to its extended hinge region, possibly facilitating interactions with immune cells. We replaced the hinge of IgG1 with four different IgG3-hinge segment subclasses, IgGhxx. Hinge-engineering does not diminish binding as with IgG3 but enhances opsonic function, where a 47 amino acid hinge is comparable to IgG3 in function. IgGh47 shows improved protection against S. pyogenes in a systemic infection mouse model, suggesting that IgGh47 has promise as a preclinical therapeutic candidate. Importantly, the enhanced opsonic function of IgGh47 is generalizable to diverse S. pyogenes strains from clinical isolates. We generated IgGh47 versions of anti-SARS-CoV-2 mAbs to broaden the biological applicability, and these also exhibit strongly enhanced opsonic function compared to the IgG1 subclass. The improved function of the IgGh47 subclass in two distant biological systems provides new insights into antibody function.
Assuntos
COVID-19 , Fragmentos Fc das Imunoglobulinas , Imunoglobulina G , SARS-CoV-2 , Streptococcus pyogenes , Animais , Humanos , Camundongos , Anticorpos Antibacterianos/imunologia , Anticorpos Monoclonais/imunologia , Anticorpos Antivirais/imunologia , COVID-19/imunologia , COVID-19/virologia , Fragmentos Fc das Imunoglobulinas/imunologia , Fragmentos Fc das Imunoglobulinas/genética , Fragmentos Fc das Imunoglobulinas/química , Imunoglobulina G/química , Imunoglobulina G/genética , Imunoglobulina G/imunologia , Camundongos Endogâmicos BALB C , Fagocitose , Engenharia de Proteínas/métodos , SARS-CoV-2/imunologia , Infecções Estreptocócicas/imunologia , Infecções Estreptocócicas/microbiologia , Streptococcus pyogenes/imunologiaRESUMO
In eukaryotic cells, there are two well characterized pathways that regulate translation initiation in response to stress, and each have been shown to be targeted by various viruses. We recently showed in a yeast-based model that the bacterial virulence factor YopJ disrupts one of these pathways, which is centered on the α-subunit of the translation factor eIF2. Here, we show in mammalian cells that induction of the eIF2 signaling pathway occurs following infection with bacterial pathogens and that, consistent with our yeast-based findings, YopJ reduces eIF2 signaling in response to endoplasmic reticulum stress, heavy metal toxicity, dsRNA, and bacterial infection. We demonstrate that the well documented activities of YopJ, inhibition of NF-κB activation and proinflammatory cytokine expression, are both dependent on an intact eIF2 signaling pathway. Unexpectedly, we found that cells with defective eIF2 signaling were more susceptible to bacterial invasion. This was true for pathogenic Yersinia, a facultative intracellular pathogen, as well as for the intracellular pathogens Listeria monocytogenes and Chlamydia trachomatis. Collectively, our data indicate that the highly conserved eIF2 signaling pathway, which is vitally important for antiviral responses, plays a variety of heretofore unrecognized roles in antibacterial responses.
Assuntos
Infecções por Chlamydia/metabolismo , Chlamydia trachomatis/metabolismo , Citocinas/biossíntese , Fator de Iniciação 2 em Eucariotos/metabolismo , Mediadores da Inflamação/metabolismo , Listeria monocytogenes/metabolismo , Listeriose/metabolismo , Transdução de Sinais , Yersiniose/metabolismo , Yersinia/metabolismo , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/imunologia , Proteínas de Bactérias/metabolismo , Linhagem Celular , Infecções por Chlamydia/genética , Infecções por Chlamydia/imunologia , Chlamydia trachomatis/genética , Chlamydia trachomatis/imunologia , Citocinas/genética , Citocinas/imunologia , Fator de Iniciação 2 em Eucariotos/genética , Fator de Iniciação 2 em Eucariotos/imunologia , Mediadores da Inflamação/imunologia , Listeria monocytogenes/genética , Listeria monocytogenes/imunologia , Listeriose/genética , Listeriose/imunologia , Camundongos , NF-kappa B/genética , NF-kappa B/imunologia , NF-kappa B/metabolismo , Yersinia/genética , Yersinia/imunologia , Yersiniose/genética , Yersiniose/imunologiaRESUMO
Group A streptococcus (GAS) is a highly adapted, human-specific pathogen that is known to manipulate the immune system through various mechanisms. GAS' M protein constitutes a primary target of the immune system due to its spatial configuration and dominance on the bacterial surface. Antibody responses targeting the M protein have been shown to favor the conserved C region. Such antibodies (Abs) circumvent antigenic escape and efficiently bind to various M types. The ability of GAS to bind to fibronectin (Fn), a high molecular weight glycoprotein of the extracellular matrix, has long been known to be essential for the pathogen's evolutionary success and fitness. However, some strains lack the ability to efficiently bind Fn. Instead, they have been found to additionally bind Fn via the A-B domains of their M proteins. Here, we show that human Abs can induce increased Fn-binding affinity in M proteins, likely by enhancing the weak A-B domain binding. We found that this enhanced Fn binding leads to a reduction in Ab-mediated phagocytosis, indicating that this constitutes a GAS immune escape mechanism. We could show that the Fc domain of Abs is necessary to trigger this phenomenon and that Ab flexibility may also play a key role. We, moreover, saw that our Abs could enhance Fn binding in 3 out of 5 emm type strains tested, belonging to different clades, making it likely that this is a more generalizable phenomenon. Together our results suggest a novel synergistic interplay of GAS and host proteins which ultimately benefits the bacterium.
RESUMO
Group A streptococci have evolved multiple strategies to evade human antibodies, making it challenging to create effective vaccines or antibody treatments. Here, we have generated antibodies derived from the memory B cells of an individual who had successfully cleared a group A streptococcal infection. The antibodies bind with high affinity in the central region of the surface-bound M protein. Such antibodies are typically non-opsonic. However, one antibody could effectively promote vital immune functions, including phagocytosis and in vivo protection. Remarkably, this antibody primarily interacts through a bivalent dual-Fab cis mode, where the Fabs bind to two distinct epitopes in the M protein. The dual-Fab cis-binding phenomenon is conserved across different groups of M types. In contrast, other antibodies binding with normal single-Fab mode to the same region cannot bypass the M protein's virulent effects. A broadly binding, protective monoclonal antibody could be a candidate for anti-streptococcal therapy. Our findings highlight the concept of dual-Fab cis binding as a means to access conserved, and normally non-opsonic regions, regions for protective antibody targeting.
Assuntos
Anticorpos Monoclonais , Antígenos de Bactérias , Humanos , Epitopos , FagocitoseRESUMO
Candida albicans is a common opportunistic pathogen that causes a wide variety of diseases in a human immunocompromised host leading to death. In a pathogen, cell wall proteins are important for stability as well as for acting as antigenic determinants and virulence factors. Pir32 is a cell wall protein and member of the Pir protein family previously shown to be upregulated in response to macrophage contact and whose other member, Pir1, was found to be necessary for cell wall rigidity. The purpose of this study is to characterize Pir32 by generating a homozygous null strain and comparing the phenotype of the null with that of the wild-type parental strain as far as filamentation, virulence in a mouse model of disseminated candidiasis, resistance to oxidative stress and cell wall disrupting agents, in addition to adhesion, biofilm capacities, and cell wall chitin content. Our mutant was shown to be hyperfilamentous, resistant to sodium dodecyl sulfate, hydrogen peroxide, sodium chloride, and more virulent in a mouse model when compared to the wild type. These results were unexpected, considering that most cell wall mutations weaken the wall and render it more susceptible to external stress factors and suggests the possibility of a cell surface compensatory mechanism. As such, we measured cell wall chitin deposition and found a twofold increase in the mutant, possibly explaining the above-observed phenotypes.
Assuntos
Candida albicans/fisiologia , Parede Celular/metabolismo , Quitina/metabolismo , Proteínas Fúngicas/genética , Deleção de Genes , Estresse Fisiológico , Animais , Candida albicans/citologia , Candida albicans/metabolismo , Candida albicans/patogenicidade , Candidíase/microbiologia , Candidíase/patologia , Modelos Animais de Doenças , Peróxido de Hidrogênio/toxicidade , Camundongos , Camundongos Endogâmicos BALB C , Viabilidade Microbiana/efeitos dos fármacos , Microscopia , Pressão Osmótica , Estresse Oxidativo , Cloreto de Sódio/metabolismo , Dodecilsulfato de Sódio/toxicidade , VirulênciaRESUMO
The human pathogen Streptococcus pyogenes causes substantial morbidity and mortality. It is unclear if antibodies developed after infections with this pathogen are opsonic and if they are strain specific or more broadly protective. Here, we quantified the opsonic-antibody response following invasive S. pyogenes infection. Four patients with S. pyogenes bacteremia between 2018 and 2020 at Skåne University Hospital in Lund, Sweden, were prospectively enrolled. Acute- and convalescent-phase sera were obtained, and the S. pyogenes isolates were genome sequenced (emm118, emm85, and two emm1 isolates). Quantitative antibody binding and phagocytosis assays were used to evaluate isolate-dependent opsonic antibody function in response to infection. Antibody binding increased modestly against the infecting isolate and across emm types in convalescent- compared to acute-phase sera for all patients. For two patients, phagocytosis increased in convalescent-phase serum both for the infecting isolate and across types. The increase was only across types for one patient, and one had no improvement. No correlation to the clinical outcomes was observed. Invasive S. pyogenes infections result in a modestly increased antibody binding with differential opsonic capacity, both nonfunctional binding and broadly opsonic binding across types. These findings question the dogma that an invasive infection should lead to a strong type-specific antibody increase rather than a more modest but broadly reactive response, as seen in these patients. Furthermore, our results indicate that an increase in antibody titers might not be indicative of an opsonic response and highlight the importance of evaluating antibody function in S. pyogenes infections. IMPORTANCE The bacterium Streptococcus pyogenes is a common cause of both mild and severe human diseases resulting in substantial morbidity and mortality each year. No vaccines are available, and our understanding of the antibody response to this human pathogen is still incomplete. Here, we carefully analyzed the opsonic antibody response following invasive infection in four patients. Unexpectedly, the patients did not always generate opsonic antibodies against the specific infecting strain. Instead, we found that some patients could generate cross-opsonic antibodies, leading to phagocytosis of bacteria across strains. The emergence of cross-opsonic antibodies is likely important for long-term immunity against S. pyogenes. Our findings question the dogma that mostly strain-specific immunity is developed after infection and add to our overall understanding of how immunity to S. pyogenes can evolve.
Assuntos
Bacteriemia , Infecções Estreptocócicas , Humanos , Infecções Estreptocócicas/microbiologia , Fagocitose , Streptococcus pyogenes/genética , Anticorpos Antibacterianos , Antígenos de Bactérias/genéticaRESUMO
The fungal pathogen Candida albicans is a leading causative agent of death in immunocompromised individuals. Many factors have been implicated in virulence including filamentation-inducing transcription factors, adhesins, lipases and proteases. Many of these factors are glycosylphosphatidylinositol-anchored cell surface antigenic determinant proteins. Pga1 is one such protein shown to be upregulated during cell wall regeneration. The purpose of this study was to characterise the role Pga1 plays by creating a homozygous pga1 null strain and comparing the phenotype with the parental strain. It was observed that the mutant strain showed less oxidative stress tolerance and an increased susceptibility to calcofluor white, a cell surface disrupting agent that inhibits chitin fibre assembly which translated as a 40% decrease in cell wall chitin content. Furthermore, the mutant exhibited a 50% reduction in adhesion and a 33% reduction in biofilm formation compared with the parental strain, which was reflected as a slight reduction in virulence. Our data suggest that Pga1 plays an important role in cell wall rigidity and stability. It was also observed that the pga1 null was over filamentous on both liquid and solid media and exhibited increased resistance to SDS suggesting upregulation of filamentation-inducing genes and cell surface components to partially compensate for the deletion.
Assuntos
Biofilmes/crescimento & desenvolvimento , Candida albicans/fisiologia , Adesão Celular , Proteínas Fúngicas/metabolismo , Proteínas de Membrana/metabolismo , Fatores de Virulência/metabolismo , Animais , Candida albicans/genética , Candidíase/microbiologia , Candidíase/mortalidade , Candidíase/patologia , Linhagem Celular Tumoral , Parede Celular/química , Proteínas Fúngicas/genética , Deleção de Genes , Humanos , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos BALB C , Análise de Sobrevida , Virulência , Fatores de Virulência/genéticaRESUMO
Streptococcus pyogenes is a major bacterial pathogen in the human population and isolates of the clinically important M1 serotype secrete protein Streptococcal inhibitor of complement (SIC) known to interfere with human innate immunity. Here we find that SIC from M1 bacteria interacts with TLR2 and CD14 on monocytes leading to the activation of the NF-κB and p38 MAPK pathways and the release of several pro-inflammatory cytokines (e.g. TNFα and INFγ). In human plasma, SIC binds clusterin and histidine-rich glycoprotein, and whole plasma, and these two purified plasma proteins enhanced the activation of monocytes by SIC. Isolates of the M55 serotype secrete an SIC homolog, but this protein did not activate monocytes. M1 isolates are common in cases of invasive S. pyogenes infections characterized by massive inflammation, and the results of this study indicate that the pro-inflammatory property of SIC contributes to the pathology of these severe clinical conditions.
RESUMO
Spike-specific antibodies are central to effective COVID19 immunity. Research efforts have focused on antibodies that neutralize the ACE2-Spike interaction but not on non-neutralizing antibodies. Antibody-dependent phagocytosis is an immune mechanism enhanced by opsonization, where typically, more bound antibodies trigger a stronger phagocyte response. Here, we show that Spike-specific antibodies, dependent on concentration, can either enhance or reduce Spike-bead phagocytosis by monocytes independently of the antibody neutralization potential. Surprisingly, we find that both convalescent patient plasma and patient-derived monoclonal antibodies lead to maximum opsonization already at low levels of bound antibodies and is reduced as antibody binding to Spike protein increases. Moreover, we show that this Spike-dependent modulation of opsonization correlate with the outcome in an experimental SARS-CoV-2 infection model. These results suggest that the levels of anti-Spike antibodies could influence monocyte-mediated immune functions and propose that non-neutralizing antibodies could confer protection to SARS-CoV-2 infection by mediating phagocytosis.
Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , COVID-19/imunologia , Opsonização/imunologia , Fagocitose/imunologia , SARS-CoV-2/imunologia , Glicoproteína da Espícula de Coronavírus/imunologia , Anticorpos Monoclonais/imunologia , Linhagem Celular , Células HEK293 , Humanos , Testes de Neutralização/métodosRESUMO
Yersinia pestis, the causative agent of plague, possesses a number of virulence mechanisms that allows it to survive and proliferate during its interaction with the host. To discover additional infection-specific Y. pestis factors, a transposon site hybridization (TraSH)-based genome-wide screen was employed to identify genomic regions required for its survival during cellular infection. In addition to several well-characterized infection-specific genes, this screen identified three chromosomal genes (y3397, y3399, and y3400), located in an apparent operon, that promoted successful infection. Each of these genes is predicted to encode a leucine-rich repeat family protein with or without an associated ubiquitin E3 ligase domain. These genes were designated Yersinia leucine-rich repeat gene A (ylrA), B (ylrB), and C (ylrC). Engineered strains with deletions of y3397 (ylrC), y3399 (ylrB), or y3400 (ylrA), exhibited infection defects both in cultured cells and in the mouse. C-terminal FLAG-tagged YlrA, YlrB, and YlrC were secreted by Y. pestis in the absence but not the presence of extracellular calcium and deletions of the DNA sequences encoding the predicted N-terminal type III secretion signals of YlrA, YlrB, and YlrC prevented their secretion, indicating that these proteins are substrates of the type III secretion system (T3SS). Further strengthening the connection with the T3SS, YlrB was readily translocated into HeLa cells and expression of the YlrA and YlrC proteins in yeast inhibited yeast growth, indicating that these proteins may function as anti-host T3S effector proteins.
Assuntos
Interações Hospedeiro-Patógeno , Peste/fisiopatologia , Sistemas de Secreção Tipo III/metabolismo , Fatores de Virulência/metabolismo , Yersinia pestis/patogenicidade , Animais , Transporte Biológico , Cromossomos Bacterianos , Modelos Animais de Doenças , Deleção de Genes , Genes Bacterianos , Testes Genéticos , Células HeLa , Humanos , Camundongos , Modelos Teóricos , Células RAW 264.7 , Virulência , Fatores de Virulência/genética , Yersinia pestis/genéticaRESUMO
Chlamydia trachomatis infections are a global health problem and new approaches to treat C. trachomatis with drugs of high specificity would be valuable. A library of substituted ring fused 2-pyridones has been synthesized and evaluated for their ability to attenuate C. trachomatis infectivity. In vivo pharmacokinetic studies were performed, with the best candidates demonstrating that a C8-methylsulfonamide substituent improved pharmacokinetic properties important for oral administration. C8-Methyl sulfonamide analogue 30 inhibited C. trachomatis infectivity in low micromolar concentrations. Further pharmacokinetic evaluation at an oral dose of 10 mg kg-1 showed an apparent bioavailability of 41%, compared to C8-cyclopropyl and -methoxy analogues which had negligible oral uptake. In vitro ADME (absorption, distribution, metabolism and excretion) testing of solubility and Caco-2 cell permeability revealed that both solubility and permeability is greatly improved with the C8-methyl sulfonamide 30, effectively moving it from BCS (Biopharmaceutical Classification System) class IV to II.
RESUMO
In this study, we describe the application of a transformed Chlamydia trachomatis strain constitutively expressing the red fluorescent protein mCherry, to allow real-time monitoring of the infection cycle and screening for agents that block replication of C. trachomatis. The red fluorescent C. trachomatis strain was detected autonomously without antibody staining and was equally susceptible to doxycycline as the wild type strain. A high-throughput screening assay was developed using the transformed strain and automated fluorescence microscopy. The assay was used in a pilot screen of a 349 compound library containing natural products from Australian flora and fauna. Compounds with anti-chlamydial activity were tested for dose response and toxicity to host cells and two non-toxic compounds had 50% effective concentration (EC50) values in the low micromolar range. Natural products are valuable sources for drug discovery and the identified Chlamydia growth inhibition may be starting points for future drug development. Live cell imaging was used to visualize growth of the red fluorescent C. trachomatis strain over time. The screening assay reduced workload and reagents compared to an assay requiring immunostaining and could further be used to monitor the development of Chlamydia inclusions and anti-chlamydial effect in real time.
RESUMO
Chlamydia trachomatis is a global health burden due to its prevalence as a sexually transmitted disease and as the causative agent of the eye infection trachoma. We recently discovered 3-amido thiazolino 2-pyridones which attenuated C. trachomatis infectivity without affecting host cell or commensal bacteria viability. We present here the synthesis and evaluation of nonhydrolyzable amide isosteres based on this class, leading to highly potent 1,2,3-triazole based infectivity inhibitors (EC50 ≤ 20 nM).
Assuntos
Amidas/farmacologia , Antifúngicos/farmacologia , Chlamydia trachomatis/efeitos dos fármacos , Piridonas/farmacologia , Tiazóis/farmacologia , Amidas/síntese química , Amidas/toxicidade , Antifúngicos/síntese química , Antifúngicos/toxicidade , Chlamydia trachomatis/patogenicidade , Células HeLa , Humanos , Testes de Mutagenicidade , Piridonas/síntese química , Piridonas/toxicidade , Tiazóis/síntese química , Tiazóis/toxicidadeRESUMO
The bacterial pathogen Chlamydia trachomatis is a global health burden currently treated with broad-spectrum antibiotics which disrupt commensal bacteria. We recently identified a compound through phenotypic screening that blocked infectivity of this intracellular pathogen without host cell toxicity (compound 1, KSK 120). Herein, we present the optimization of 1 to a class of thiazolino 2-pyridone amides that are highly efficacious (EC50 ≤ 100 nM) in attenuating infectivity across multiple serovars of C. trachomatis without host cell toxicity. The lead compound 21a exhibits reduced lipophilicity versus 1 and did not affect the growth or viability of representative commensal flora at 50 µM. In microscopy studies, a highly active fluorescent analogue 37 localized inside the parasitiphorous inclusion, indicative of a specific targeting of bacterial components. In summary, we present a class of small molecules to enable the development of specific treatments for C. trachomatis.