The gut commensal Bacteroides vulgatus mpk reduces Candida albicans pathogenicity towards epithelial cells

The human body is colonized by various microbes, among them the yeast Candida albicans. Mostly harmless, this opportunist causes also disease, ranging from superficial infections to sepsis. Risk factors are disturbed host defenses, mucosal barrier breakdown, and antibiotic-induced dysbiosis. Hence, residing bacteria are important to protect from Candida-mediated damage or inflammation. Bacteroides vulgatus mpk, e.g., is described as positively immunomodulatory in mouse models of inflammatory bowel disease, but its effect on the mycobiota is unknown. In this study we aimed to determine if B. vulgatus mpk affects C. albicans pathogenicity. Therefore, intestinal and oral epithelial cellswere pre-infectedin vitrowith B. vulgatus mpk and then challenged with C. albicans SC5314. The role of soluble factors was investigated by spatial separation or use of Bacteroides-conditioned medium (BCM). Preincubation of host cells with B. vulgatus mpk strongly reduced C. albicans-mediated damage while fungal burden and hyphal length were unaffected by the bacterium. The protective effect did not depend on direct contact of Bacteroidesto host cellsor Candida and could be mimicked using BCM. Contact independency suggests that diffusible factors modulate host cell susceptibility. Ongoing experiments aim to identifykey soluble Bacteroides mediators as well as subsequent host cell signaling. Additionally, co-colonization experiments of germ-free mice are planned to investigate B. vulgatus mpk’s potential to mediate colonization resistance towards C. albicans. This will contribute to our understanding of how commensal bacteria affect C. albicans and host protection.

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Candida albicans Als3, a Multifunctional Adhesin and Invasin

Eukaryotic Cell ◽

10.1128/ec.00279-10 ◽

2010 ◽

Vol 10 (2) ◽

pp. 168-173 ◽

Cited By ~ 159

Author(s):

Yaoping Liu ◽

Scott G. Filler

Keyword(s):

Candida Albicans ◽

Host Cell ◽

Surface Protein ◽

Host Cells ◽

Content Type ◽

Multifunctional Protein ◽

Multiple Functions ◽

Abiotic Surfaces ◽

Disseminated Disease

ABSTRACTCandida albicansis part of the normal human flora, and it grows on mucosal surfaces in healthy individuals. In susceptible hosts, this organism can cause both mucosal and hematogenously disseminated disease. ForC. albicansto persist in the host and induce disease, it must be able to adhere to biotic and abiotic surfaces, invade host cells, and obtain iron. TheC. albicanshypha-specific surface protein Als3 is a member of the agglutinin-like sequence (Als) family of proteins and is important in all of these processes. Functioning as an adhesin, Als3 mediates attachment to epithelial cells, endothelial cells, and extracellular matrix proteins. It also plays an important role in biofilm formation on prosthetic surfaces, both alone and in mixed infection withStreptococcus gordonii. Als3 is one of two knownC. albicansinvasins. It binds to host cell receptors such as E-cadherin and N-cadherin and thereby induces host cells to endocytose the organism. Als3 also binds to host cell ferritin and enablesC. albicansto utilize this protein as a source of iron. Because of its multiple functions and its high expression levelin vivo, Als3 is a promising target for vaccines that induce protective cell-mediated and antibody responses. This review will summarize the multiple functions of this interesting and multifunctional protein.

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Metabolic Signatures of Cryptosporidium parvum-Infected HCT-8 Cells and Impact of Selected Metabolic Inhibitors on C. parvum Infection under Physioxia and Hyperoxia

Biology ◽

10.3390/biology10010060 ◽

2021 ◽

Vol 10 (1) ◽

pp. 60

Author(s):

Juan Vélez ◽

Zahady Velasquez ◽

Liliana M. R. Silva ◽

Ulrich Gärtner ◽

Klaus Failing ◽

...

Keyword(s):

Host Cell ◽

Cryptosporidium Parvum ◽

Cell Metabolism ◽

Lactate Production ◽

Glucose Consumption ◽

Host Cells ◽

Metabolic Inhibitors ◽

Low Oxygen ◽

Metabolic Signatures

Cryptosporidium parvum is an apicomplexan zoonotic parasite recognized as the second leading-cause of diarrhoea-induced mortality in children. In contrast to other apicomplexans, C.parvum has minimalistic metabolic capacities which are almost exclusively based on glycolysis. Consequently, C. parvum is highly dependent on its host cell metabolism. In vivo (within the intestine) infected epithelial host cells are typically exposed to low oxygen pressure (1–11% O2, termed physioxia). Here, we comparatively analyzed the metabolic signatures of C. parvum-infected HCT-8 cells cultured under both, hyperoxia (21% O2), representing the standard oxygen condition used in most experimental settings, and physioxia (5% O2), to be closer to the in vivo situation. The most pronounced effect of C. parvum infection on host cell metabolism was, on one side, an increase in glucose and glutamine uptake, and on the other side, an increase in lactate release. When cultured in a glutamine-deficient medium, C. parvum infection led to a massive increase in glucose consumption and lactate production. Together, these results point to the important role of both glycolysis and glutaminolysis during C. parvum intracellular replication. Referring to obtained metabolic signatures, we targeted glycolysis as well as glutaminolysis in C. parvum-infected host cells by using the inhibitors lonidamine [inhibitor of hexokinase, mitochondrial carrier protein (MCP) and monocarboxylate transporters (MCT) 1, 2, 4], galloflavin (lactate dehydrogenase inhibitor), syrosingopine (MCT1- and MCT4 inhibitor) and compound 968 (glutaminase inhibitor) under hyperoxic and physioxic conditions. In line with metabolic signatures, all inhibitors significantly reduced parasite replication under both oxygen conditions, thereby proving both energy-related metabolic pathways, glycolysis and glutaminolysis, but also lactate export mechanisms via MCTs as pivotal for C. parvum under in vivo physioxic conditions of mammals.

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The Campylobacter jejuni CiaD effector co-opts the host cell protein IQGAP1 to promote cell entry

Nature Communications ◽

10.1038/s41467-021-21579-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Nicholas M. Negretti ◽

Christopher R. Gourley ◽

Prabhat K. Talukdar ◽

Geremy Clair ◽

Courtney M. Klappenbach ◽

...

Keyword(s):

Host Cell ◽

Campylobacter Jejuni ◽

Foodborne Pathogen ◽

Small Gtpase ◽

Host Cells ◽

Cell Protein ◽

Host Cell Protein ◽

Cell Binding ◽

Actin Reorganization ◽

Cell Cytosol

AbstractCampylobacter jejuni is a foodborne pathogen that binds to and invades the epithelial cells lining the human intestinal tract. Maximal invasion of host cells by C. jejuni requires cell binding as well as delivery of the Cia proteins (Campylobacter invasion antigens) to the host cell cytosol via the flagellum. Here, we show that CiaD binds to the host cell protein IQGAP1 (a Ras GTPase-activating-like protein), thus displacing RacGAP1 from the IQGAP1 complex. This, in turn, leads to the unconstrained activity of the small GTPase Rac1, which is known to have roles in actin reorganization and internalization of C. jejuni. Our results represent the identification of a host cell protein targeted by a flagellar secreted effector protein and demonstrate that C. jejuni-stimulated Rac signaling is dependent on IQGAP1.

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A Single-Pass Type I Membrane Protein from the Apicomplexan Parasite Cryptosporidium parvum with Nanomolar Binding Affinity to Host Cell Surface

Microorganisms ◽

10.3390/microorganisms9051015 ◽

2021 ◽

Vol 9 (5) ◽

pp. 1015

Author(s):

Tianyu Zhang ◽

Xin Gao ◽

Dongqiang Wang ◽

Jixue Zhao ◽

Nan Zhang ◽

...

Keyword(s):

Membrane Protein ◽

Cell Surface ◽

Host Cell ◽

Binding Affinity ◽

Cryptosporidium Parvum ◽

Host Cells ◽

Watery Diarrhea ◽

Type I ◽

Single Pass ◽

Host Cell Surface

Cryptosporidium parvum is a globally recognized zoonotic parasite of medical and veterinary importance. This parasite mainly infects intestinal epithelial cells and causes mild to severe watery diarrhea that could be deadly in patients with weakened or defect immunity. However, its molecular interactions with hosts and pathogenesis, an important part in adaptation of parasitic lifestyle, remain poorly understood. Here we report the identification and characterization of a C. parvum T-cell immunomodulatory protein homolog (CpTIPH). CpTIPH is a 901-aa single-pass type I membrane protein encoded by cgd5_830 gene that also contains a short Vibrio, Colwellia, Bradyrhizobium and Shewanella (VCBS) repeat and relatively long integrin alpha (ITGA) N-terminus domain. Immunofluorescence assay confirmed the location of CpTIPH on the cell surface of C. parvum sporozoites. In congruence with the presence of VCBS repeat and ITGA domain, CpTIPH displayed high, nanomolar binding affinity to host cell surface (i.e., Kd(App) at 16.2 to 44.7 nM on fixed HCT-8 and CHO-K1 cells, respectively). The involvement of CpTIPH in the parasite invasion is partly supported by experiments showing that an anti-CpTIPH antibody could partially block the invasion of C. parvum sporozoites into host cells. These observations provide a strong basis for further investigation of the roles of CpTIPH in parasite-host cell interactions.

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Revisiting Ehrlichia ruminantium Replication Cycle Using Proteomics: The Host and the Bacterium Perspectives

Microorganisms ◽

10.3390/microorganisms9061144 ◽

2021 ◽

Vol 9 (6) ◽

pp. 1144

Author(s):

Isabel Marcelino ◽

Philippe Holzmuller ◽

Ana Coelho ◽

Gabriel Mazzucchelli ◽

Bernard Fernandez ◽

...

Keyword(s):

Endothelial Cells ◽

Host Cell ◽

Cell Metabolism ◽

Replication Cycle ◽

Host Cells ◽

Ehrlichia Ruminantium ◽

Host Interaction ◽

Infected Cells ◽

Related Proteins

The Rickettsiales Ehrlichia ruminantium, the causal agent of the fatal tick-borne disease Heartwater, induces severe damage to the vascular endothelium in ruminants. Nevertheless, E. ruminantium-induced pathobiology remains largely unknown. Our work paves the way for understanding this phenomenon by using quantitative proteomic analyses (2D-DIGE-MS/MS, 1DE-nanoLC-MS/MS and biotin-nanoUPLC-MS/MS) of host bovine aorta endothelial cells (BAE) during the in vitro bacterium intracellular replication cycle. We detect 265 bacterial proteins (including virulence factors), at all time-points of the E. ruminantium replication cycle, highlighting a dynamic bacterium–host interaction. We show that E. ruminantium infection modulates the expression of 433 host proteins: 98 being over-expressed, 161 under-expressed, 140 detected only in infected BAE cells and 34 exclusively detected in non-infected cells. Cystoscape integrated data analysis shows that these proteins lead to major changes in host cell immune responses, host cell metabolism and vesicle trafficking, with a clear involvement of inflammation-related proteins in this process. Our findings led to the first model of E. ruminantium infection in host cells in vitro, and we highlight potential biomarkers of E. ruminantium infection in endothelial cells (such as ROCK1, TMEM16K, Albumin and PTPN1), which may be important to further combat Heartwater, namely by developing non-antibiotic-based strategies.

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The Importance of Therapeutically Targeting the Binary Toxin from Clostridioides difficile

International Journal of Molecular Sciences ◽

10.3390/ijms22062926 ◽

2021 ◽

Vol 22 (6) ◽

pp. 2926

Author(s):

Dinendra L. Abeyawardhane ◽

Raquel Godoy-Ruiz ◽

Kaylin A. Adipietro ◽

Kristen M. Varney ◽

Richard R. Rustandi ◽

...

Keyword(s):

Host Cell ◽

The Elderly ◽

Cell Receptor ◽

Host Cells ◽

Binary Toxin ◽

Clostridioides Difficile ◽

Host Cell Receptor ◽

Oligomeric Assembly ◽

Nosocomial Disease ◽

Binary Toxins

Novel therapeutics are needed to treat pathologies associated with the Clostridioides difficile binary toxin (CDT), particularly when C. difficile infection (CDI) occurs in the elderly or in hospitalized patients having illnesses, in addition to CDI, such as cancer. While therapies are available to block toxicities associated with the large clostridial toxins (TcdA and TcdB) in this nosocomial disease, nothing is available yet to treat toxicities arising from strains of CDI having the binary toxin. Like other binary toxins, the active CDTa catalytic subunit of CDT is delivered into host cells together with an oligomeric assembly of CDTb subunits via host cell receptor-mediated endocytosis. Once CDT arrives in the host cell’s cytoplasm, CDTa catalyzes the ADP-ribosylation of G-actin leading to degradation of the cytoskeleton and rapid cell death. Although a detailed molecular mechanism for CDT entry and host cell toxicity is not yet fully established, structural and functional resemblances to other binary toxins are described. Additionally, unique conformational assemblies of individual CDT components are highlighted herein to refine our mechanistic understanding of this deadly toxin as is needed to develop effective new therapeutic strategies for treating some of the most hypervirulent and lethal strains of CDT-containing strains of CDI.

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Pathogen induced subversion of NAD+ metabolism mediating host cell death: a target for development of chemotherapeutics

Cell Death Discovery ◽

10.1038/s41420-020-00366-z ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Ayushi Chaurasiya ◽

Swati Garg ◽

Ashish Khanna ◽

Chintam Narayana ◽

Ved Prakash Dwivedi ◽

...

Keyword(s):

Cell Death ◽

Host Cell ◽

Nicotinamide Adenine Dinucleotide ◽

Malaria Parasite ◽

Host Cells ◽

Nicotinamide Adenine ◽

Targeted Therapeutics ◽

Nad Metabolism ◽

Host Cell Death ◽

Nanomolar Range

AbstractHijacking of host metabolic status by a pathogen for its regulated dissemination from the host is prerequisite for the propagation of infection. M. tuberculosis secretes an NAD+-glycohydrolase, TNT, to induce host necroptosis by hydrolyzing Nicotinamide adenine dinucleotide (NAD+). Herein, we expressed TNT in macrophages and erythrocytes; the host cells for M. tuberculosis and the malaria parasite respectively, and found that it reduced the NAD+ levels and thereby induced necroptosis and eryptosis resulting in premature dissemination of pathogen. Targeting TNT in M. tuberculosis or induced eryptosis in malaria parasite interferes with pathogen dissemination and reduction in the propagation of infection. Building upon our discovery that inhibition of pathogen-mediated host NAD+ modulation is a way forward for regulation of infection, we synthesized and screened some novel compounds that showed inhibition of NAD+-glycohydrolase activity and pathogen infection in the nanomolar range. Overall this study highlights the fundamental importance of pathogen-mediated modulation of host NAD+ homeostasis for its infection propagation and novel inhibitors as leads for host-targeted therapeutics.

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Mbov_0503 Encodes a Novel Cytoadhesin that Facilitates Mycoplasma bovis Interaction with Tight Junctions

Microorganisms ◽

10.3390/microorganisms8020164 ◽

2020 ◽

Vol 8 (2) ◽

pp. 164 ◽

Cited By ~ 1

Author(s):

Xifang Zhu ◽

Yaqi Dong ◽

Eric Baranowski ◽

Xixi Li ◽

Gang Zhao ◽

...

Keyword(s):

Host Cell ◽

Tight Junctions ◽

Binding Capacity ◽

Host Cells ◽

Mycoplasma Bovis ◽

Knock Out ◽

Cell Monolayers ◽

Protein Levels ◽

Complex Process ◽

Host Cell Surface

Molecules contributing to microbial cytoadhesion are important virulence factors. In Mycoplasma bovis, a minimal bacterium but an important cattle pathogen, binding to host cells is emerging as a complex process involving a broad range of surface-exposed structures. Here, a new cytoadhesin of M. bovis was identified by producing a collection of individual knock-out mutants and evaluating their binding to embryonic bovine lung cells. The cytoadhesive-properties of this surface-exposed protein, which is encoded by Mbov_0503 in strain HB0801, were demonstrated at both the mycoplasma cell and protein levels using confocal microscopy and ELISA. Although Mbov_0503 disruption was only associated in M. bovis with a partial reduction of its binding capacity, this moderate effect was sufficient to affect M. bovis interaction with the host-cell tight junctions, and to reduce the translocation of this mycoplasma across epithelial cell monolayers. Besides demonstrating the capacity of M. bovis to disrupt tight junctions, these results identified novel properties associated with cytoadhesin that might contribute to virulence and host colonization. These findings provide new insights into the complex interplay taking place between wall-less mycoplasmas and the host-cell surface.

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Perturbation of host autophagy by the Irish potato famine pathogen

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314091736 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C826-C826

Author(s):

Abbas Maqbool ◽

Richard Richard ◽

Tolga Bozkurt ◽

Yasin Dagdas ◽

Khaoula Belhai ◽

...

Keyword(s):

Host Cell ◽

Plant Cells ◽

Irish Potato ◽

Effector Proteins ◽

Host Cells ◽

Cell Physiology ◽

Biochemical Basis ◽

The Impact ◽

Potato Famine ◽

Irish Potato Famine

Autophagy is a catabolic process involving degradation of dysfunctional cytoplasmic components to ensure cellular survival under starvation conditions. The process involves formation of double-membrane vesicles called autophagosomes and delivery of the inner constituents to lytic compartments. It can also target invading pathogens, such as intracellular bacteria, for destruction and is thus implicated in innate immune pathways [1]. In response, certain mammalian pathogens deliver effector proteins into host cells that inhibit autophagy and contribute to enabling parasitic infection [2]. Pyhtophthora infestans, the Irish potato famine pathogen, is a causative agent of late blight disease in potato and tomato crops. It delivers a plethora of modular effector proteins into plant cells to promote infection. Once inside the cell, RXLR-type effector proteins engage with host cell proteins, to manipulate host cell physiology for the benefit of the pathogen. As plants lack an adaptive immune system, this provides a robust mechanism for pathogens to circumvent host defense. PexRD54 is an intracellular RXLR-type effector protein produced by P. infestans. PexRD54 interacts with potato homologues of autophagy protein ATG8 in plant cells. We have been investigating the structural and biochemical basis of the PexRD54/ATG8 interaction in vitro. We have purified PexRD54 and ATG8 independently and in complex from E. coli. Using protein/protein interaction studies we have shown that PexRD54 binds ATG8 with sub-micromolar affinity. We have also determined the structure of PexRD54 in the presence of ATG8. This crystal structure provides key insights into how the previously reported WY-fold of oomycete RXLR-type effectors [3] can be organized in multiple repeats. The structural data also provides insights into the interaction between PexRD54 and ATG8, suggesting further experiments to understand the impact of this interaction on host cell physiology and how this benefits the pathogen.

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Cellular and immunological basis of the host-parasite relationship during infection withNeospora caninum

Parasitology ◽

10.1017/s0031182006000485 ◽

2006 ◽

Vol 133 (3) ◽

pp. 261-278 ◽

Cited By ~ 76

Author(s):

A. HEMPHILL ◽

N. VONLAUFEN ◽

A. NAGULESWARAN

Keyword(s):

Host Cell ◽

Cell Biology ◽

Neospora Caninum ◽

Host Cells ◽

Term Survival ◽

Prevention Of Infection ◽

Parasite Relationship ◽

Potential Applications

Neospora caninumis an apicomplexan parasite that is closely related toToxoplasma gondii, the causative agent of toxoplasmosis in humans and domestic animals. However, in contrast toT. gondii, N. caninumrepresents a major cause of abortion in cattle, pointing towards distinct differences in the biology of these two species. There are 3 distinct key features that represent potential targets for prevention of infection or intervention against disease caused byN. caninum. Firstly, tachyzoites are capable of infecting a large variety of host cellsin vitroandin vivo. Secondly, the parasite exploits its ability to respond to alterations in living conditions by converting into another stage (tachyzoite-to-bradyzoite orvice versa). Thirdly, by analogy withT. gondii, this parasite has evolved mechanisms that modulate its host cells according to its own requirements, and these must, especially in the case of the bradyzoite stage, involve mechanisms that ensure long-term survival of not only the parasite but also of the host cell. In order to elucidate the molecular and cellular bases of these important features ofN. caninum, cell culture-based approaches and laboratory animal models are being exploited. In this review, we will summarize the current achievements related to host cell and parasite cell biology, and will discuss potential applications for prevention of infection and/or disease by reviewing corresponding work performed in murine laboratory infection models and in cattle.

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