scholarly journals Hemoglobin stimulates vigorous growth of Streptococcus pneumoniae and shapes the pathogen's global transcriptome

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Fahmina Akhter ◽  
Edroyal Womack ◽  
Jorge E. Vidal ◽  
Yoann Le Breton ◽  
Kevin S. McIver ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Positive Influence ◽  
The Body ◽  
Host Proteins ◽  
Vigorous Growth ◽  
Cultivation In Vitro ◽  
The Impact ◽  
Heme Binding Protein

Abstract Streptococcus pneumoniae (Spn) must acquire iron from the host to establish infection. We examined the impact of hemoglobin, the largest iron reservoir in the body, on pneumococcal physiology. Supplementation with hemoglobin allowed Spn to resume growth in an iron-deplete medium. Pneumococcal growth with hemoglobin was unusually robust, exhibiting a prolonged logarithmic growth, higher biomass, and extended viability in both iron-deplete and standard medium. We observed the hemoglobin-dependent response in multiple serotypes, but not with other host proteins, free iron, or heme. Remarkably, hemoglobin induced a sizable transcriptome remodeling, effecting virulence and metabolism in particular genes facilitating host glycoconjugates use. Accordingly, Spn was more adapted to grow on the human α − 1 acid glycoprotein as a sugar source with hemoglobin. A mutant in the hemoglobin/heme-binding protein Spbhp-37 was impaired for growth on heme and hemoglobin iron. The mutant exhibited reduced growth and iron content when grown in THYB and hemoglobin. In summary, the data show that hemoglobin is highly beneficial for Spn cultivation in vitro and suggest that hemoglobin might drive the pathogen adaptation in vivo. The hemoglobin receptor, Spbhp-37, plays a role in mediating the positive influence of hemoglobin. These novel findings provide intriguing insights into pneumococcal interactions with its obligate human host.

scholarly journals Exploration of bacterial bottlenecks and Streptococcus pneumoniae pathogenesis by CRISPRi-seq

2020 ◽  
Author(s):  
Xue Liu ◽  
Jacqueline M. Kimmey ◽  
Vincent de Bakker ◽  
Victor Nizet ◽  
Jan-Willem Veening
Keyword(s):  
Streptococcus Pneumoniae ◽  
Post Infection ◽  
Systemic Infection ◽  
The Body ◽  
Genetic Screens ◽  
Animal Pathogens ◽  
Genes Encoding ◽  
One Step

AbstractStreptococcus pneumoniae is a commensal bacterium of the human nasopharynx, but can cause harmful infections if it spreads to other parts of the body, such as pneumonia, sepsis or meningitis. To facilitate pathogenesis studies, we constructed a doxycycline-inducible pooled CRISPR interference (CRISPRi) library targeting all operons in protypical S. pneumoniae strain D39V. Our library design allows fitness within the pool to be assessed by a one-step PCR reaction directly followed by Illumina sequencing (CRISPRi-seq). The doxycycline-inducible CRISPRi system is tightly controllable and suitable for both bottleneck exploration and evaluation of gene fitness in vitro and in vivo. Here, we applied CRISPRi-seq to identify genetic factors important for causing pneumococcal pneumonia. Mice were infected intratracheally with our CRISPRi library and bacteria collected at 24 h (from lung) and 48 h (from both lung and blood) post-infection. CRISPRi-seq showed a critical bottleneck at 48 h after intratracheal infection, with only a few bacteria surviving the brunt of the innate immune response to cause systemic infection. However, earlier at 24 h post-infection, many significant differences in gene fitness cost between in vitro and in vivo conditions were identified, including genes encoding known and putative novel virulence factors, genes essential only in vivo, and genes essential only in vitro. A key advantage of CRISPRi-seq over traditional transposon-based genetic screens is that all genes, including essential genes, can be tested for their role in virulence and pathogenicity. The approaches developed here should be generally applicable to study infection bottlenecks and in vivo fitness for other important human and animal pathogens.

scholarly journals The Two-Component System 09 of Streptococcus pneumoniae Is Important for Metabolic Fitness and Resistance during Dissemination in the Host

2021 ◽  
Vol 9 (7) ◽  
pp. 1365
Author(s):  
Stephanie Hirschmann ◽  
Alejandro Gómez-Mejia ◽  
Thomas P. Kohler ◽  
Franziska Voß ◽  
Manfred Rohde ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Regulatory System ◽  
Immunoblot Analysis ◽  
Defined Medium ◽  
Host Cells ◽  
Two Component ◽  
Regulatory Effects ◽  
The Impact

The two-component regulatory system 09 of Streptococcus pneumoniae has been shown to modulate resistance against oxidative stress as well as capsule expression. These data and the implication of TCS09 in cell wall integrity have been shown for serotype 2 strain D39. Other data have suggested strain-specific regulatory effects of TCS09. Contradictory data are known on the impact of TCS09 on virulence, but all have been explored using only the rr09-mutant. In this study, we have therefore deleted one or both components of the TCS09 (SP_0661 and SP_0662) in serotype 4 S. pneumoniae TIGR4. In vitro growth assays in chemically defined medium (CDM) using sucrose or lactose as a carbon source indicated a delayed growth of nonencapsulated tcs09-mutants, while encapsulated wild-type TIGR4 and tcs09-mutants have reduced growth in CDM with glucose. Using a set of antigen-specific antibodies, immunoblot analysis showed that only the pilus 1 backbone protein RrgB is significantly reduced in TIGR4ΔcpsΔhk09. Electron microscopy, adherence and phagocytosis assays showed no impact of TCS09 on the TIGR4 cell morphology and interaction with host cells. In contrast, in vivo infections and in particular competitive co-infection experiments demonstrated that TCS09 enhances robustness during dissemination in the host by maintaining bacterial fitness.

scholarly journals Development and Physiological Functions of the Lymphatic System - Insights from Genetic Studies of Lymphedema

2021 ◽  
Author(s):  
Silvia Martin-Almedina ◽  
Peter Mortimer ◽  
Pia Ostergaard
Keyword(s):  
Lymphatic System ◽  
Imaging Techniques ◽  
The Body ◽  
Genetic Studies ◽  
Disease Mechanisms ◽  
Primary Lymphedema ◽  
And Function ◽  
The Impact

Primary lymphedema is a long-term (chronic) condition characterized by tissue lymph retention and swelling that can affect any part of the body, although it usually develops in the arms or legs. Due to the relevant contribution of the lymphatic system to human physiology, while this review mainly focusses on the clinical and physiological aspects related to the regulation of fluid homeostasis and edema, clinicians need to know that the impact of lymphatic dysfunction with a genetic origin can be wide ranging. Lymphatic gene dysfunction can affect immune function so leading to infection; it can influence cancer development and spread; and it can determine fat transport so impacting on nutrition and obesity. Genetic studies and the development of imaging techniques for the assessment of lymphatic function have enabled the recognition of primary lymphedema as a heterogenic condition in terms of genetic causes and disease mechanisms. In this review, the known biological function of several genes crucial to the development and function of the lymphatic system are used as a basis for understanding normal lymphatic biology. The disease conditions originating from mutations in these genes are discussed together with a detailed clinical description of the phenotype and the up-to-date knowledge in terms of disease mechanisms acquired from in vitro and in vivo research models.

scholarly journals Corynebacterium Species Inhibit Streptococcus pneumoniae Colonization and Infection of the Mouse Airway

2022 ◽  
Vol 12 ◽  
Author(s):  
Kadi J. Horn ◽  
Alexander C. Jaberi Vivar ◽  
Vera Arenas ◽  
Sameer Andani ◽  
Edward N. Janoff ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Respiratory Health ◽  
Upper Airway ◽  
Inhibitory Effect ◽  
Airway Microbiome ◽  
The Stability ◽  
Independent Effects ◽  
The Impact

The stability and composition of the airway microbiome is an important determinant of respiratory health. Some airway bacteria are considered to be beneficial due to their potential to impede the acquisition and persistence of opportunistic bacterial pathogens such as Streptococcus pneumoniae. Among such organisms, the presence of Corynebacterium species correlates with reduced S. pneumoniae in both adults and children, in whom Corynebacterium abundance is predictive of S. pneumoniae infection risk. Previously, Corynebacterium accolens was shown to express a lipase which cleaves host lipids, resulting in the production of fatty acids that inhibit growth of S. pneumoniae in vitro. However, it was unclear whether this mechanism contributes to Corynebacterium-S. pneumoniae interactions in vivo. To address this question, we developed a mouse model for Corynebacterium colonization in which colonization with either C. accolens or another species, Corynebacterium amycolatum, significantly reduced S. pneumoniae acquisition in the upper airway and infection in the lung. Moreover, the lungs of co-infected mice had reduced pro-inflammatory cytokines and inflammatory myeloid cells, indicating resolution of infection-associated inflammation. The inhibitory effect of C. accolens on S. pneumoniae in vivo was mediated by lipase-dependent and independent effects, indicating that both this and other bacterial factors contribute to Corynebacterium-mediated protection in the airway. We also identified a previously uncharacterized bacterial lipase in C. amycolatum that is required for inhibition of S. pneumoniae growth in vitro. Together, these findings demonstrate the protective potential of airway Corynebacterium species and establish a new model for investigating the impact of commensal microbiota, such as Corynebacterium, on maintaining respiratory health.

scholarly journals NLRP3 inflammasome activation in aged macrophages is diminished during Streptococcus pneumoniae infection

2018 ◽  
Vol 314 (3) ◽  
pp. L372-L387 ◽  
Author(s):  
Soo Jung Cho ◽  
Kristen Rooney ◽  
Augustine M. K. Choi ◽  
Heather W. Stout-Delgado
Keyword(s):  
Streptococcus Pneumoniae ◽  
Nlrp3 Inflammasome ◽  
The United States ◽  
Biological Aging ◽  
Inflammasome Activation ◽  
Pneumococcal Infections ◽  
Nlrp3 Inflammasome Activation ◽  
The Impact

Pneumococcal infections are the eigth leading cause of death in the United States, and it is estimated that older patients (≥65 yr of age) account for the most serious cases. The goal of our current study is to understand the impact of biological aging on innate immune responses to Streptococcus pneumoniae, a causative agent of bacterial pneumonia. With the use of in vitro and in vivo aged murine models, our findings demonstrate that age-enhanced unfolded protein responses (UPRs) contribute to diminished inflammasome assembly and activation during S. pneumoniae infection. Pretreatment of aged mice with endoplasmic reticulum chaperone and the stress-reducing agent tauroursodeoxycholic acid (TUDCA) decreased mortality in aged hosts that was associated with increased NLRP3 inflammasome activation, improved pathogen clearance, and decreased pneumonitis during infection. Taken together, our data provide new evidence as to why older persons are more susceptible to S. pneumoniae and provide a possible therapeutic target to decrease morbidity and mortality in this population.

scholarly journals Convergence of Regulatory Networks on the Pilus Locus of Streptococcus pneumoniae

2008 ◽  
Vol 76 (7) ◽  
pp. 3187-3196 ◽  
Author(s):  
Jason W. Rosch ◽  
Beth Mann ◽  
Justin Thornton ◽  
Jack Sublett ◽  
Elaine Tuomanen
Keyword(s):  
Streptococcus Pneumoniae ◽  
Regulatory Networks ◽  
Genetic Recombination ◽  
Lung Epithelial Cells ◽  
Infection Model ◽  
Transcriptional Regulatory Networks ◽  
Transport Response ◽  
The Impact

ABSTRACT The rlrA pilus locus of Streptococcus pneumoniae is an example of a pathogenicity island acquired through genetic recombination. Many acquired genetic elements commandeer preexisting networks of the new organism for transcriptional regulation. We hypothesized that the rlrA locus has integrated into transcriptional regulatory networks controlling expression of virulence factors important in adhesion and invasion. To test this hypothesis, we determined the impact on pilus expression of known regulators controlling adherence, including the two-component systems CbpR/S and HK/RR03 and the transcriptional regulators of divalent cation transporters MerR and PsaR in vitro and in vivo. It was determined that the pilus locus is down-regulated by preexisting networks designed for adhesion and cation transport/response and that its regulation occurs through RlrA. The pilus locus was found to participate in invasion specifically restricted to lung epithelial cells in vitro. While expression of pili had only a small effect on virulence with an intranasal infection model, pili were critically important with an intratracheal infection model. Thus, expression of pili appears to have become integrated into the regulatory circuits for lung-specific invasion by pneumococci.

scholarly journals Immune response and pathogen invasion at the choroid plexus in the onset of cerebral toxoplasmosis

2022 ◽  
Vol 19 (1) ◽  
Author(s):  
Caio Andreeta Figueiredo ◽  
Johannes Steffen ◽  
Lorena Morton ◽  
Sushmitha Arumugam ◽  
Oliver Liesenfeld ◽  
...  
Keyword(s):  
Immune Response ◽  
Endothelial Cells ◽  
Epithelial Cells ◽  
Choroid Plexus ◽  
The Body ◽  
Potential Contribution ◽  
Pathogen Invasion ◽  
The Impact

Abstract Background Toxoplasma gondii (T. gondii) is a highly successful parasite being able to cross all biological barriers of the body, finally reaching the central nervous system (CNS). Previous studies have highlighted the critical involvement of the blood–brain barrier (BBB) during T. gondii invasion and development of subsequent neuroinflammation. Still, the potential contribution of the choroid plexus (CP), the main structure forming the blood–cerebrospinal fluid (CSF) barrier (BCSFB) have not been addressed. Methods To investigate T. gondii invasion at the onset of neuroinflammation, the CP and brain microvessels (BMV) were isolated and analyzed for parasite burden. Additionally, immuno-stained brain sections and three-dimensional whole mount preparations were evaluated for parasite localization and morphological alterations. Activation of choroidal and brain endothelial cells were characterized by flow cytometry. To evaluate the impact of early immune responses on CP and BMV, expression levels of inflammatory mediators, tight junctions (TJ) and matrix metalloproteinases (MMPs) were quantified. Additionally, FITC-dextran was applied to determine infection-related changes in BCSFB permeability. Finally, the response of primary CP epithelial cells to T. gondii parasites was tested in vitro. Results Here we revealed that endothelial cells in the CP are initially infected by T. gondii, and become activated prior to BBB endothelial cells indicated by MHCII upregulation. Additionally, CP elicited early local immune response with upregulation of IFN-γ, TNF, IL-6, host-defence factors as well as swift expression of CXCL9 chemokine, when compared to the BMV. Consequently, we uncovered distinct TJ disturbances of claudins, associated with upregulation of MMP-8 and MMP-13 expression in infected CP in vivo, which was confirmed by in vitro infection of primary CP epithelial cells. Notably, we detected early barrier damage and functional loss by increased BCSFB permeability to FITC-dextran in vivo, which was extended over the infection course. Conclusions Altogether, our data reveal a close interaction between T. gondii infection at the CP and the impairment of the BCSFB function indicating that infection-related neuroinflammation is initiated in the CP.

Potentials of medicinal nanostructured diamond particles and coatings

2021 ◽  
Author(s):  
Moataz Dowaidar
Keyword(s):  
Chemical Stability ◽  
Clinical Medicine ◽  
The Body ◽  
Specific Cell ◽  
Diamond Surfaces ◽  
Diamond Particles ◽  
In Vivo Testing ◽  
The Impact

Particles and coatings can be manufactured utilizing low-cost, scalable processes. In both in vitro and in vivo experiments, unmodified diamond materials displayed good cell biocompatibility. Most current nanostructured diamond research focuses on diamond surfaces for specific cell and tissue interactions. Although the chemical stability of functionalized diamond surfaces has been explored for relatively short periods of time, the functionalized surface's chemical stability while its use in the body deserves additional exploration. In addition, the impact of chemistry (e.g., pH), enzymes, and microorganisms on the functionalized diamond surface's chemical stability must be considered. Moreover, the goals of studies evaluating the biological functionality of nanostructured diamond materials must be better aligned with regulatory requirements (e.g., ASTM International and the International Organization for Standardization) and in vitro and in vivo testing requirements of government agencies (e.g. the U.S. Food & Drug Administration). Because national regulatory authorities generally review medical devices rather than biomaterials, the parameters of in vitro and in vivo research should be closer to the implantation site's biological, chemical and mechanical features. Research on the breakdown of nanostructured diamond devices and the presence of degradation products in surrounding and remote tissues is needed. Thinking about how the sterilizing technique impacts the surface properties and biocompatibility of nanostructured diamond materials is equally significant. As the stability and fate of functionalized diamond particles and surfaces is better known via more in-vitro and in-vivo testing, nanostructured diamond materials are likely to play a greater role in clinical medicine.

scholarly journals Immune Response and Pathogen Invasion at the Choroid Plexus in the Onset of Cerebral Toxoplasmosis

2021 ◽  
Author(s):  
Caio Andreeta Figueiredo ◽  
JOhannes Steffen ◽  
Lorena Morton ◽  
Sushmita Arumugam ◽  
OLiver Liesenfeld ◽  
...  
Keyword(s):  
Immune Response ◽  
Endothelial Cells ◽  
Epithelial Cells ◽  
Choroid Plexus ◽  
The Body ◽  
Potential Contribution ◽  
Pathogen Invasion ◽  
The Impact

Abstract Background: Toxoplasma gondii ( T. gondii ) is a highly successful parasite being able to cross all biological barriers of the body, finally reaching the central nervous system (CNS). Previous studies have highlighted the critical involvement of the blood-brain barrier (BBB) during T. gondii invasion and development of subsequent neuroinflammation. Still, the potential contribution of the choroid plexus (CP), a main structure forming the blood-cerebrospinal fluid (CSF)-barrier (BCSFB) have not been addressed. Methods: To investigate T. gondii invasion and the onset of neuroinflammation, the CP and brain microvessels (BMV) were isolated and analysed for parasite burden. Additionally, immuno-stained brain sections and three dimensional whole mount preparations were evaluated for parasite localization and morphological alterations. Activation of choroidal and brain endothelial cells were characterized by flow cytometry. To evaluate the impact of early immune responses on CP and BMV, expression levels of inflammatory mediators, tight junctions (TJ) and matrix metalloproteinases (MMPs) were quantified. Additionally, FITC-dextran was applied to determine infection-related changes in BCSFB permeability. Finally, the response of primary CP epithelial cells to T. gondii parasites was tested in vitro . Results: Here we revealed that endothelial cells in the CP are initially infected by T. gondii, and become activated prior to BBB endothelial cells indicated by MHCII upregulation. Additionally, CP elicited early local immune response with upregulation of IFN-γ, TNF, IL-6, host-defence factors as well as swift expression of CXCL9 chemokine, when compared to the BMV. Consequently, we uncovered distinct TJ disturbances of claudins, associated with upregulation of MMP-8 and MMP-13 expression in infected CP in vivo , which was confirmed by in vitro infection of primary CP epithelial cells. Notably, we detected early barrier damage and functional loss by increased BCSFB permeability to FITC-dextran in vivo , which was extended over the infection course. Conclusions: Altogether, our data reveal a close interaction between T. gondii infection at the CP and the impairment of the BCSFB function indicating that infection-related neuroinflammation is initiated in the CP.

scholarly journals Edward F. Adolph Distinguished Lecture: Skin-deep insights into vascular aging

2017 ◽  
Vol 123 (5) ◽  
pp. 1024-1038 ◽  
Author(s):  
W. Larry Kenney
Keyword(s):  
Vascular Function ◽  
Microvascular Dysfunction ◽  
The Body ◽  
Doppler Flowmetry ◽  
Microvascular Changes ◽  
Age Related ◽  
Aged Skin ◽  
The Impact

The skin is an accessible model circulation for studying vascular function and dysfunction across the lifespan. Age-related changes, as well as those associated with disease progression, often appear first in the cutaneous circulation. Furthermore, impaired vascular signaling and attendant endothelial dysfunction, the earliest indicators of cardiovascular pathogenesis, occur in a similar fashion across multiple tissue beds throughout the body, including the skin. Because microvascular dysfunction is a better predictor of long-term outcomes and adverse cardiovascular events than is large vessel disease, an understanding of age-associated changes in the control of the human cutaneous microcirculation is important. This review focuses on 1) the merits of using skin-specific methods and techniques to study vascular function, 2) microvascular changes in aged skin (in particular, the role of the endothelial-derived dilator nitric oxide), and 3) the impact of aging on heat-induced changes in skin vasodilation. While skin blood flow is controlled by multiple, often redundant, mechanisms, our laboratory has used a variety of distinct thermal provocations of this model circulation to isolate specific age-associated changes in vascular function. Skin-specific approaches and techniques, such as intradermal microdialysis coupled with laser-Doppler flowmetry (in vivo) and biochemical analyses of skin biopsy samples (in vitro), have allowed for the targeted pharmacodissection of the mechanistic pathways controlling skin vasoreactivity and study of the impact of aging and disease states. Aged skin has an attenuated ability to vasodilate in response to warm stimuli and to vasoconstrict in response to cold stimuli.

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