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1.
PLoS Pathog ; 19(10): e1011665, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37824458

RESUMO

Malaria is a devastating infectious disease and significant global health burden caused by the bite of a Plasmodium-infected female Anopheles mosquito. Gut microbiota was recently discovered as a risk factor of severe malaria. This review entails the recent advances on the impact of gut microbiota composition on malaria severity and consequence of malaria infection on gut microbiota in mammalian hosts. Additionally, this review provides mechanistic insight into interactions that might occur between gut microbiota and host immunity which in turn can modulate malaria severity. Finally, approaches to modulate gut microbiota composition are discussed. We anticipate this review will facilitate novel hypotheses to move the malaria-gut microbiome field forward.


Assuntos
Anopheles , Microbioma Gastrointestinal , Malária , Plasmodium , Animais , Feminino , Humanos , Fatores de Risco , Mamíferos
2.
Proc Natl Acad Sci U S A ; 118(12)2021 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-33723045

RESUMO

The randomization and screening of combinatorial DNA libraries is a powerful technique for understanding sequence-function relationships and optimizing biosynthetic pathways. Although it can be difficult to predict a priori which sequence combinations encode functional units, it is often possible to omit undesired combinations that inflate library size and screening effort. However, defined library generation is difficult when a complex scan through sequence space is needed. To overcome this challenge, we designed a hybrid valve- and droplet-based microfluidic system that deterministically assembles DNA parts in picoliter droplets, reducing reagent consumption and bias. Using this system, we built a combinatorial library encoding an engineered histidine kinase (HK) based on bacterial CpxA. Our library encodes designed transmembrane (TM) domains that modulate the activity of the cytoplasmic domain of CpxA and variants of the structurally distant "S helix" located near the catalytic domain. We find that the S helix sets a basal activity further modulated by the TM domain. Surprisingly, we also find that a given TM motif can elicit opposing effects on the catalytic activity of different S-helix variants. We conclude that the intervening HAMP domain passively transmits signals and shapes the signaling response depending on subtle changes in neighboring domains. This flexibility engenders a richness in functional outputs as HKs vary in response to changing evolutionary pressures.


Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , DNA/química , DNA/metabolismo , Microfluídica , Engenharia de Proteínas , Domínios e Motivos de Interação entre Proteínas , Proteínas Quinases/química , Proteínas Quinases/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Ativação Enzimática , Expressão Gênica , Biblioteca Gênica , Microfluídica/instrumentação , Microfluídica/métodos , Modelos Moleculares , Conformação Molecular , Engenharia de Proteínas/métodos , Proteínas Quinases/genética , Relação Estrutura-Atividade
3.
J Am Chem Soc ; 145(48): 26095-26105, 2023 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-37989570

RESUMO

Peptide-induced transmembrane pore formation is commonplace in biology. Examples of transmembrane pores include pores formed by antimicrobial peptides (AMPs) and cell-penetrating peptides (CPPs) in bacterial membranes and eukaryotic membranes, respectively. In general, however, transmembrane pore formation depends on peptide sequences, lipid compositions, and intensive thermodynamic variables and is difficult to observe directly under realistic solution conditions, with structures that are challenging to measure directly. In contrast, the structure and phase behavior of peptide-lipid systems are relatively straightforward to map out experimentally for a broad range of conditions. Cubic phases are often observed in systems involving pore-forming peptides; however, it is not clear how the structural tendency to induce negative Gaussian curvature (NGC) in such phases is quantitatively related to the geometry of biological pores. Here, we leverage the theory of anisotropic inclusions and devise a facile method to estimate transmembrane pore sizes from geometric parameters of cubic phases measured from small-angle X-ray scattering (SAXS) and show that such estimates compare well with known pore sizes. Moreover, our model suggests that although AMPs can induce stable transmembrane pores for membranes with a broad range of conditions, pores formed by CPPs are highly labile, consistent with atomistic simulations.


Assuntos
Peptídeos Penetradores de Células , Peptídeos Penetradores de Células/química , Bicamadas Lipídicas/química , Espalhamento a Baixo Ângulo , Difração de Raios X , Sequência de Aminoácidos
4.
BMC Biol ; 18(1): 83, 2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32620114

RESUMO

BACKGROUND: Experimental reproducibility in mouse models is impacted by both genetics and environment. The generation of reproducible data is critical for the biomedical enterprise and has become a major concern for the scientific community and funding agencies alike. Among the factors that impact reproducibility in experimental mouse models is the variable composition of the microbiota in mice supplied by different commercial vendors. Less attention has been paid to how the microbiota of mice supplied by a particular vendor might change over time. RESULTS: In the course of conducting a series of experiments in a mouse model of malaria, we observed a profound and lasting change in the severity of malaria in mice infected with Plasmodium yoelii; while for several years mice obtained from a specific production suite of a specific commercial vendor were able to clear the parasites effectively in a relatively short time, mice subsequently shipped from the same unit suffered much more severe disease. Gut microbiota analysis of frozen cecal samples identified a distinct and lasting shift in bacteria populations that coincided with the altered response of the later shipments of mice to infection with malaria parasites. Germ-free mice colonized with cecal microbiota from mice within the same production suite before and after this change followed by Plasmodium infection provided a direct demonstration that the change in gut microbiota profoundly impacted the severity of malaria. Moreover, spatial changes in gut microbiota composition were also shown to alter the acute bacterial burden following Salmonella infection, and tumor burden in a lung tumorigenesis model. CONCLUSION: These changes in gut bacteria may have impacted the experimental reproducibility of diverse research groups and highlight the need for both laboratory animal providers and researchers to collaborate in determining the methods and criteria needed to stabilize the gut microbiota of animal breeding colonies and research cohorts, and to develop a microbiota solution to increase experimental rigor and reproducibility.


Assuntos
Modelos Animais de Doenças , Microbioma Gastrointestinal , Malária/fisiopatologia , Plasmodium yoelii/fisiologia , Animais , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Análise Espaço-Temporal
5.
J Infect Dis ; 220(4): 687-698, 2019 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-30590681

RESUMO

BACKGROUND: Gut microbiota were recently shown to impact malaria disease progression and outcome, and prior studies have shown that Plasmodium infections increase the likelihood of enteric bacteria causing systemic infections. Currently, it is not known whether Plasmodium infection impacts human gut microbiota as a prelude to bacteremia or whether antimalarials affect gut microbiota. Our goal was to determine to what degree Plasmodium infections and antimalarial treatment affect human gut microbiota. METHODS: One hundred Kenyan infants underwent active surveillance for malaria from birth to 10 months of age. Each malaria episode was treated with artemether-lumefantrine (AL). Any other treatments, including antibiotics, were recorded. Stool samples were collected on an approximately biweekly basis. Ten children were selected on the basis of stool samples having been collected before (n = 27) or after (n = 17) a malaria episode and without antibiotics having been administered between collections. These samples were subjected to 16S ribosomal ribonucleic acid gene (V3-V4 region) sequencing. RESULTS: Bacterial community network analysis revealed no obvious differences in the before and after malaria/AL samples, which was consistent with no difference in alpha and beta diversity and taxonomic analysis at the family and genus level with one exception. At the sequence variant (SV) level, akin to bacterial species, only 1 of the top 100 SVs was significantly different. In addition, predicted metagenome analysis revealed no significant difference in metagenomic capacity between before and after malaria/AL samples. The number of malaria episodes, 1 versus 2, explained significant variation in gut microbiota composition of the infants. CONCLUSIONS: In-depth bioinformatics analysis of stool bacteria has revealed for the first time that human malaria episode/AL treatment have minimal effects on gut microbiota in Kenyan infants.


Assuntos
Antimaláricos/administração & dosagem , Combinação Arteméter e Lumefantrina/administração & dosagem , Microbioma Gastrointestinal , Malária/tratamento farmacológico , Plasmodium/efeitos dos fármacos , Biologia Computacional , Disbiose , Fezes/microbiologia , Feminino , Febre , Humanos , Lactente , Quênia , Estudos Longitudinais , Malária/patologia , Masculino , RNA Ribossômico 16S/genética
6.
Proc Natl Acad Sci U S A ; 113(8): 2235-40, 2016 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-26858424

RESUMO

Plasmodium infections result in clinical presentations that range from asymptomatic to severe malaria, resulting in ∼1 million deaths annually. Despite this toll on humanity, the factors that determine disease severity remain poorly understood. Here, we show that the gut microbiota of mice influences the pathogenesis of malaria. Genetically similar mice from different commercial vendors, which exhibited differences in their gut bacterial community, had significant differences in parasite burden and mortality after infection with multiple Plasmodium species. Germfree mice that received cecal content transplants from "resistant" or "susceptible" mice had low and high parasite burdens, respectively, demonstrating the gut microbiota shaped the severity of malaria. Among differences in the gut flora were increased abundances of Lactobacillus and Bifidobacterium in resistant mice. Susceptible mice treated with antibiotics followed by yogurt made from these bacterial genera displayed a decreased parasite burden. Consistent with differences in parasite burden, resistant mice exhibited an elevated humoral immune response compared with susceptible mice. Collectively, these results identify the composition of the gut microbiota as a previously unidentified risk factor for severe malaria and modulation of the gut microbiota (e.g., probiotics) as a potential treatment to decrease parasite burden.


Assuntos
Microbioma Gastrointestinal , Malária/microbiologia , Animais , Antibacterianos/uso terapêutico , Bifidobacterium/isolamento & purificação , Bifidobacterium/fisiologia , Microbioma Gastrointestinal/imunologia , Microbioma Gastrointestinal/fisiologia , Vida Livre de Germes , Interações Hospedeiro-Parasita/imunologia , Humanos , Lactobacillus/isolamento & purificação , Lactobacillus/fisiologia , Malária/parasitologia , Malária/terapia , Camundongos , Camundongos Endogâmicos C57BL , Carga Parasitária , Plasmodium yoelii , Probióticos/uso terapêutico
7.
Clin Infect Dis ; 67(12): 1831-1839, 2018 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-29701835

RESUMO

Background: The microbiome influences malaria parasite fitness and transmission efficiency in mosquitoes and appears to affect malaria dynamics in mammalian hosts as well. Nascent research examining the interrelationship of malaria and the mammalian microbiome has yielded interesting insights inviting further study. Methods: We conducted a systematic review of the literature examining associations between the microbiome and malaria in mammalian hosts. An electronic search algorithm was adapted to PubMed, MEDLINE, Scopus, Embase, and Web of Science, and reference lists of relevant sources were manually searched. Identified studies were screened and assessed independently by 2 authors, and results were compiled in a qualitative synthesis of the evidence. Results: Ten relevant studies were identified. They demonstrate associations between certain intestinal communities and protection against Plasmodium infection and modulation of disease severity. Plasmodium infection acutely and reversibly reshapes gut microbial composition in mice. The makeup of human skin microbial communities may influence mosquito attraction and thus disease transmission. Conclusions: Early research supports a relationship between malaria and the microbiome. The evidence is incomplete, but the observed associations are evocative and signal a promising avenue of inquiry. Microbiome-based studies of malaria can be readily integrated into field-based research.


Assuntos
Interações Hospedeiro-Parasita , Malária/prevenção & controle , Microbiota , Pele/microbiologia , Animais , Culicidae/parasitologia , Microbioma Gastrointestinal , Humanos , Malária/transmissão , Camundongos , Plasmodium
8.
PLoS Pathog ; 12(6): e1005705, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27355424

RESUMO

Triggering antimicrobial mechanisms in macrophages infected with intracellular pathogens, such as mycobacteria, is critical to host defense against the infection. To uncover the unique and shared antimicrobial networks induced by the innate and adaptive immune systems, gene expression profiles generated by RNA sequencing (RNAseq) from human monocyte-derived macrophages (MDMs) activated with TLR2/1 ligand (TLR2/1L) or IFN-γ were analyzed. Weighed gene correlation network analysis identified modules of genes strongly correlated with TLR2/1L or IFN-γ that were linked by the "defense response" gene ontology term. The common TLR2/1L and IFN-γ inducible human macrophage host defense network contained 16 antimicrobial response genes, including S100A12, which was one of the most highly induced genes by TLR2/1L. There is limited information on the role of S100A12 in infectious disease, leading us to test the hypothesis that S100A12 contributes to host defense against mycobacterial infection in humans. We show that S100A12 is sufficient to directly kill Mycobacterium tuberculosis and Mycobacterium leprae. We also demonstrate that S100A12 is required for TLR2/1L and IFN-γ induced antimicrobial activity against M. leprae in infected macrophages. At the site of disease in leprosy, we found that S100A12 was more strongly expressed in skin lesions from tuberculoid leprosy (T-lep), the self-limiting form of the disease, compared to lepromatous leprosy (L-lep), the progressive form of the disease. These data suggest that S100A12 is part of an innate and adaptive inducible antimicrobial network that contributes to host defense against mycobacteria in infected macrophages.


Assuntos
Hanseníase/imunologia , Macrófagos/imunologia , Proteína S100A12/imunologia , Citometria de Fluxo , Imunofluorescência , Perfilação da Expressão Gênica , Humanos , Macrófagos/microbiologia , Infecções por Mycobacterium/imunologia , Mycobacterium leprae/imunologia , Mycobacterium tuberculosis/imunologia , Reação em Cadeia da Polimerase em Tempo Real , Transcriptoma
9.
Biopolymers ; 109(8): e23096, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29319162

RESUMO

The hydrophobic Aß peptide is highly aggregation prone; it first forms soluble oligomers, which then convert into the amyloid fibrils found in the cerebral plaques of Alzheimer's disease. It is generally understood that as the peptide concentration of Aß increases, the fibrillization process is accelerated, but we examine the limits on this phenomenon. We found that once a threshold concentration of Aß is exceeded, a stable oligomer is formed at the expense of fibril formation. The suppression of fibril formation was observed by amyloid-binding dye Thioflavin T and solution nuclear magnetic resonance (NMR). Small-angle X-ray scattering, size exclusion chromatography, and analytical ultracentrifugation demonstrated that Aß peptides form a range of compact species, with a dimer being an early highly populated oligomer. Solution NMR allowed us to define the secondary structure of this Aß dimer, which shows interlocking contacts between C-terminal peptide strands. Thus, we present a novel Aß oligomer that resists conversion to fibrils and remains stable for more than one year.


Assuntos
Peptídeos beta-Amiloides/química , Benzotiazóis/química , Ressonância Magnética Nuclear Biomolecular , Fragmentos de Peptídeos/química , Agregados Proteicos , Humanos , Estabilidade Proteica
10.
Bioconjug Chem ; 28(3): 793-804, 2017 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-28248495

RESUMO

We design hybrid antibiotic peptide conjugates that can permeate membranes. Integration of multiple components with different functions into a single molecule is often problematic, due to competing chemical requirements for different functions and to mutual interference. By examining the structure of antimicrobial peptides (AMPs), we show that it is possible to design and synthesize membrane active antibiotic peptide conjugates (MAAPCs) that synergistically combine multiple forms of antimicrobial activity, resulting in unusually strong activity against persistent bacterial strains.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/farmacologia , Sequência de Aminoácidos , Antibacterianos/metabolismo , Peptídeos Catiônicos Antimicrobianos/metabolismo , Escherichia coli/efeitos dos fármacos , Escherichia coli/metabolismo , Infecções por Escherichia coli/tratamento farmacológico , Hemólise/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Permeabilidade , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/metabolismo
11.
J Immunol ; 194(2): 697-708, 2015 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-25505280

RESUMO

Plasmodium remains a major pathogen causing malaria and impairing defense against other infections. Defining how Plasmodium increases susceptibility to heterologous pathogens may lead to interventions that mitigate the severity of coinfections. Previous studies proposed that reduced T cell responses during coinfections are due to diminished recruitment of naive T cells through infection-induced decreases in chemokine CCL21. We found that, although Listeria infections reduced expression of CCL21 in murine spleens, lymphocytic choriomeningitis virus (LCMV)-specific T cell responses were not impaired during Listeria + LCMV coinfection, arguing against a major role for this chemokine in coinfection-induced T cell suppression. In our experiments, Plasmodium yoelii infection led to a reduced CD8(+) T cell response to a subsequent Listeria infection. We propose an alternative mechanism whereby P. yoelii suppresses Listeria-specific T cell responses. We found that Listeria-specific T cells expanded more slowly and resulted in lower numbers in response to coinfection with P. yoelii. Mathematical modeling and experimentation revealed greater apoptosis of Listeria-specific effector T cells as the main mechanism, because P. yoelii infections did not suppress the recruitment or proliferation rates of Listeria-specific T cells. Our results suggest that P. yoelii infections suppress immunity to Listeria by causing increased apoptosis in Listeria-specific T cells, resulting in a slower expansion rate of T cell responses.


Assuntos
Coinfecção/imunologia , Imunidade Celular , Listeria monocytogenes/imunologia , Listeriose/imunologia , Malária/imunologia , Plasmodium yoelii/imunologia , Linfócitos T/imunologia , Animais , Apoptose/imunologia , Quimiocina CCL21/genética , Quimiocina CCL21/imunologia , Coinfecção/genética , Coinfecção/microbiologia , Coinfecção/parasitologia , Coinfecção/patologia , Listeriose/genética , Listeriose/parasitologia , Listeriose/patologia , Malária/genética , Malária/microbiologia , Malária/patologia , Camundongos , Camundongos Transgênicos
12.
Nat Mater ; 14(7): 696-700, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26053762

RESUMO

Double-stranded DNA (dsDNA) can trigger the production of type I interferon (IFN) in plasmacytoid dendritic cells (pDCs) by binding to endosomal Toll-like receptor-9 (TLR9; refs 1-5). It is also known that the formation of DNA-antimicrobial peptide complexes can lead to autoimmune diseases via amplification of pDC activation. Here, by combining X-ray scattering, computer simulations, microscopy and measurements of pDC IFN production, we demonstrate that a broad range of antimicrobial peptides and other cationic molecules cause similar effects, and elucidate the criteria for amplification. TLR9 activation depends on both the inter-DNA spacing and the multiplicity of parallel DNA ligands in the self-assembled liquid-crystalline complex. Complexes with a grill-like arrangement of DNA at the optimum spacing can interlock with multiple TLR9 like a zipper, leading to multivalent electrostatic interactions that drastically amplify binding and thereby the immune response. Our results suggest that TLR9 activation and thus TLR9-mediated immune responses can be modulated deterministically.


Assuntos
Peptídeos Catiônicos Antimicrobianos/química , DNA/química , Interferon Tipo I/metabolismo , Receptor Toll-Like 9/metabolismo , Simulação por Computador , Ilhas de CpG , Cristalização , Células Dendríticas/citologia , Endossomos/metabolismo , Humanos , Interferon-alfa/metabolismo , Cristais Líquidos , Método de Monte Carlo , Oligonucleotídeos/química , Espalhamento de Radiação , Eletricidade Estática , Raios X , Catelicidinas
13.
Biochim Biophys Acta ; 1838(9): 2269-79, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24743021

RESUMO

Novel synthetic mimics of antimicrobial peptides have been developed to exhibit structural properties and antimicrobial activity similar to those of natural antimicrobial peptides (AMPs) of the innate immune system. These molecules have a number of potential advantages over conventional antibiotics, including reduced bacterial resistance, cost-effective preparation, and customizable designs. In this study, we investigate a family of nylon-3 polymer-based antimicrobials. By combining vesicle dye leakage, bacterial permeation, and bactericidal assays with small-angle X-ray scattering (SAXS), we find that these polymers are capable of two interdependent mechanisms of action: permeation of bacterial membranes and binding to intracellular targets such as DNA, with the latter necessarily dependent on the former. We systemically examine polymer-induced membrane deformation modes across a range of lipid compositions that mimic both bacteria and mammalian cell membranes. The results show that the polymers' ability to generate negative Gaussian curvature (NGC), a topological requirement for membrane permeation and cellular entry, in model Escherichia coli membranes correlates with their ability to permeate membranes without complete membrane disruption and kill E. coli cells. Our findings suggest that these polymers operate with a concentration-dependent mechanism of action: at low concentrations permeation and DNA binding occur without membrane disruption, while at high concentrations complete disruption of the membrane occurs. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.


Assuntos
Peptídeos Catiônicos Antimicrobianos/química , Permeabilidade da Membrana Celular/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Imunidade Inata/efeitos dos fármacos , Peptídeos Catiônicos Antimicrobianos/farmacologia , Bactérias/efeitos dos fármacos , Infecções Bacterianas/tratamento farmacológico , Membrana Celular/química , Escherichia coli/efeitos dos fármacos , Humanos , Bicamadas Lipídicas/química , Nylons/química , Polímeros/química
14.
Antimicrob Agents Chemother ; 59(6): 3672-4, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25870067

RESUMO

There is an urgent need for new antimalarial agents and strategies to treat and control malaria. This study shows an antiplasmodium effect of tulathromycin in mice infected with Plasmodium yoelii. The administration of tulathromycin around the time of infection prevented the progression of disease in 100% of the animals. In addition, highly parasitized mice treated with tulathromycin showed a decreased parasite burden and cleared the parasite faster than did untreated infected mice.


Assuntos
Antimaláricos/uso terapêutico , Dissacarídeos/uso terapêutico , Compostos Heterocíclicos/uso terapêutico , Malária/tratamento farmacológico , Plasmodium yoelii/efeitos dos fármacos , Plasmodium yoelii/patogenicidade , Animais , Feminino , Camundongos
15.
Proc Natl Acad Sci U S A ; 108(41): 16883-8, 2011 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-21969533

RESUMO

Cell-penetrating peptides (CPPs), such as the HIV TAT peptide, are able to translocate across cellular membranes efficiently. A number of mechanisms, from direct entry to various endocytotic mechanisms (both receptor independent and receptor dependent), have been observed but how these specific amino acid sequences accomplish these effects is unknown. We show how CPP sequences can multiplex interactions with the membrane, the actin cytoskeleton, and cell-surface receptors to facilitate different translocation pathways under different conditions. Using "nunchuck" CPPs, we demonstrate that CPPs permeabilize membranes by generating topologically active saddle-splay ("negative Gaussian") membrane curvature through multidentate hydrogen bonding of lipid head groups. This requirement for negative Gaussian curvature constrains but underdetermines the amino acid content of CPPs. We observe that in most CPP sequences decreasing arginine content is offset by a simultaneous increase in lysine and hydrophobic content. Moreover, by densely organizing cationic residues while satisfying the above constraint, TAT peptide is able to combine cytoskeletal remodeling activity with membrane translocation activity. We show that the TAT peptide can induce structural changes reminiscent of macropinocytosis in actin-encapsulated giant vesicles without receptors.


Assuntos
Peptídeos Penetradores de Células/metabolismo , Produtos do Gene tat do Vírus da Imunodeficiência Humana/metabolismo , Sequência de Aminoácidos , Transporte Biológico Ativo , Membrana Celular/metabolismo , Peptídeos Penetradores de Células/química , Peptídeos Penetradores de Células/genética , Citoesqueleto/metabolismo , Células HeLa , Humanos , Interações Hidrofóbicas e Hidrofílicas , Técnicas In Vitro , Modelos Biológicos , Modelos Moleculares , Pinocitose , Lipossomas Unilamelares/metabolismo , Produtos do Gene tat do Vírus da Imunodeficiência Humana/química , Produtos do Gene tat do Vírus da Imunodeficiência Humana/genética
16.
Function (Oxf) ; 5(3): zqae009, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38706961

RESUMO

Global prevalence of hypertension is on the rise, burdening healthcare, especially in developing countries where infectious diseases, such as malaria, are also rampant. Whether hypertension could predispose or increase susceptibility to malaria, however, has not been extensively explored. Previously, we reported that hypertension is associated with abnormal red blood cell (RBC) physiology and anemia. Since RBC are target host cells for malarial parasite, Plasmodium, we hypothesized that hypertensive patients with abnormal RBC physiology are at greater risk or susceptibility to Plasmodium infection. To test this hypothesis, normotensive (BPN/3J) and hypertensive (BPH/2J) mice were characterized for their RBC physiology and subsequently infected with Plasmodium yoelii (P. yoelii), a murine-specific non-lethal strain. When compared to BPN mice, BPH mice displayed microcytic anemia with RBC highly resistant to osmotic hemolysis. Further, BPH RBC exhibited greater membrane rigidity and an altered lipid composition, as evidenced by higher levels of phospholipids and saturated fatty acid, such as stearate (C18:0), along with lower levels of polyunsaturated fatty acid like arachidonate (C20:4). Moreover, BPH mice had significantly greater circulating Ter119+ CD71+ reticulocytes, or immature RBC, prone to P. yoelii infection. Upon infection with P. yoelii, BPH mice experienced significant body weight loss accompanied by sustained parasitemia, indices of anemia, and substantial increase in systemic pro-inflammatory mediators, compared to BPN mice, indicating that BPH mice were incompetent to clear P. yoelii infection. Collectively, these data demonstrate that aberrant RBC physiology observed in hypertensive BPH mice contributes to an increased susceptibility to P. yoelii infection and malaria-associated pathology.


Assuntos
Eritrócitos , Hipertensão , Malária , Plasmodium yoelii , Animais , Malária/imunologia , Malária/parasitologia , Malária/complicações , Malária/sangue , Malária/fisiopatologia , Camundongos , Eritrócitos/parasitologia , Eritrócitos/metabolismo , Suscetibilidade a Doenças , Masculino , Anemia/parasitologia , Modelos Animais de Doenças , Hemólise
17.
Artigo em Inglês | MEDLINE | ID: mdl-39078977

RESUMO

CONTEXT: Obesity is prevalent in type 1 diabetes (T1D) and is problematic with higher risk for diabetes complications. It is unknown to what extent gut microbiome changes are associated with obesity and T1D. OBJECTIVE: To describe the gut microbiome and microbial metabolite changes associated with obesity in T1D. We hypothesized significant gut microbial and metabolite differences in lean T1D youth (BMI: 5-<85%) vs. those with obesity (BMI: ≥95%). METHODS: We analyzed stool samples for gut microbial (using metagenomic shotgun sequencing) and short-chain fatty acid (SCFA) differences in lean (n=27) and obese (n=21) T1D youth in a pilot study. The mean±SD age was 15.3±2.2yrs, A1c 7.8±1.3%, diabetes duration 5.1±4.4yrs, 42.0% females, and 94.0% were White. RESULTS: Bacterial community composition showed between sample diversity differences (ß-diversity) by BMI group (p=0.013). There was a higher ratio of Prevotella to Bacteroides in the obese group (p=0.0058). There was a differential distribution of significantly abundant taxa in either the lean or obese groups, including increased relative abundance of Prevotella copri, among other taxa in the obese group. Functional profiling showed an upregulation of branched chain amino acid (BCAA) biosynthesis in the obese group and upregulation of BCAA degradation, tyrosine metabolism and secondary bile acid biosynthesis in the lean group. Stool SCFAs were higher in the obese versus the lean group (p<0.05 for all). CONCLUSIONS: Our findings identify a gut microbiome and microbial metabolite signature associated with obesity in T1D. These findings could help identify gut microbiome targeted therapies to manage obesity in T1D.

18.
JCI Insight ; 9(11)2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38687615

RESUMO

A systems analysis was conducted to determine the potential molecular mechanisms underlying differential immunogenicity and protective efficacy results of a clinical trial of the radiation-attenuated whole-sporozoite PfSPZ vaccine in African infants. Innate immune activation and myeloid signatures at prevaccination baseline correlated with protection from P. falciparum parasitemia in placebo controls. These same signatures were associated with susceptibility to parasitemia among infants who received the highest and most protective PfSPZ vaccine dose. Machine learning identified spliceosome, proteosome, and resting DC signatures as prevaccination features predictive of protection after highest-dose PfSPZ vaccination, whereas baseline circumsporozoite protein-specific (CSP-specific) IgG predicted nonprotection. Prevaccination innate inflammatory and myeloid signatures were associated with higher sporozoite-specific IgG Ab response but undetectable PfSPZ-specific CD8+ T cell responses after vaccination. Consistent with these human data, innate stimulation in vivo conferred protection against infection by sporozoite injection in malaria-naive mice while diminishing the CD8+ T cell response to radiation-attenuated sporozoites. These data suggest a dichotomous role of innate stimulation for malaria protection and induction of protective immunity by whole-sporozoite malaria vaccines. The uncoupling of vaccine-induced protective immunity achieved by Abs from more protective CD8+ T cell responses suggests that PfSPZ vaccine efficacy in malaria-endemic settings may be constrained by opposing antigen presentation pathways.


Assuntos
Imunidade Inata , Vacinas Antimaláricas , Malária Falciparum , Plasmodium falciparum , Esporozoítos , Vacinas Atenuadas , Vacinas Antimaláricas/imunologia , Vacinas Antimaláricas/administração & dosagem , Imunidade Inata/imunologia , Humanos , Animais , Malária Falciparum/prevenção & controle , Malária Falciparum/imunologia , Plasmodium falciparum/imunologia , Camundongos , Vacinas Atenuadas/imunologia , Vacinas Atenuadas/administração & dosagem , Esporozoítos/imunologia , Esporozoítos/efeitos da radiação , Linfócitos T CD8-Positivos/imunologia , Lactente , Proteínas de Protozoários/imunologia , Anticorpos Antiprotozoários/imunologia , Feminino , Parasitemia/imunologia , Parasitemia/prevenção & controle , Imunoglobulina G/imunologia , Imunoglobulina G/sangue , Eficácia de Vacinas
19.
J Biol Chem ; 287(26): 21866-72, 2012 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-22566697

RESUMO

The conserved tridisulfide array of the α-defensin family imposes a common triple-stranded ß-sheet topology on peptides that may have highly diverse primary structures, resulting in differential outcomes after targeted mutagenesis. In mouse cryptdin-4 (Crp4) and rhesus myeloid α-defensin-4 (RMAD4), complete substitutions of Arg with Lys affect bactericidal peptide activity very differently. Lys-for-Arg mutagenesis attenuates Crp4, but RMAD4 activity remains mostly unchanged. Here, we show that the differential biological effect of Lys-for-Arg replacements can be understood by the distinct phase behavior of the experimental peptide-lipid system. In Crp4, small-angle x-ray scattering analyses showed that Arg-to-Lys replacements shifted the induced nanoporous phases to a different range of lipid compositions compared with the Arg-rich native peptide, consistent with the attenuation of bactericidal activity by Lys-for-Arg mutations. In contrast, such phases generated by RMAD4 were largely unchanged. The concordance between small-angle x-ray scattering measurements and biological activity provides evidence that specific types of α-defensin-induced membrane curvature-generating tendencies correspond directly to bactericidal activity via membrane destabilization.


Assuntos
Arginina/metabolismo , Precursores de Proteínas/metabolismo , alfa-Defensinas/metabolismo , Animais , Anti-Infecciosos/química , Peptídeos Catiônicos Antimicrobianos/química , Arginina/química , Defensinas/química , Escherichia coli/metabolismo , Imunidade Inata , Lipídeos/química , Lisina/química , Camundongos , Distribuição Normal , Peptídeos/química , Espalhamento de Radiação , Raios X , alfa-Defensinas/química
20.
J Am Chem Soc ; 135(37): 13710-9, 2013 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-23962302

RESUMO

The M2 protein is a multifunctional protein, which plays several roles in the replication cycle of the influenza A virus. Here we focus on its ability to promote budding of the mature virus from the cell surface. Using high-resolution small-angle X-ray scattering we show that M2 can restructure lipid membranes into bicontinuous cubic phases which are rich in negative Gaussian curvature (NGC). The active generation of negative Gaussian membrane curvature by M2 is essential to influenza virus budding. M2 has been observed to colocalize with the region of high NGC at the neck of a bud. The structural requirements for scission are even more stringent than those for budding, as the neck must be considerably smaller than the virus during 'pinch off'. Consistent with this, the amount of NGC in the induced cubic phases suggests that M2 proteins can generate high curvatures comparable to those on a neck with size 10× smaller than a spherical influenza virus. Similar experiments on variant proteins containing different M2 domains show that the cytoplasmic amphipathic helix is necessary and sufficient for NGC generation. Mutations to the helix which reduce its amphiphilicity and are known to diminish budding attenuated NGC generation. An M2 construct comprising the membrane interactive domains, the transmembrane helix and the cytoplasmic helix, displayed enhanced ability to generate NGC, suggesting that other domains cooperatively promote membrane curvature. These studies establish the importance of M2-induced NGC during budding and suggest that antagonizing this curvature is a viable anti-influenza strategy.


Assuntos
Lipídeos de Membrana/metabolismo , Orthomyxoviridae , Proteínas da Matriz Viral/metabolismo , Liberação de Vírus , Interações Hidrofóbicas e Hidrofílicas , Difração de Raios X
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