Infection of human organoids supports an intestinal niche for Chlamydia trachomatis.

Several reports suggest that intestinal tissue may be a natural niche for Chlamydia trachomatis infection and a reservoir for persistent infections in the human body. Due to the human specificity of the pathogen and the lack of suitable host models, there is limited knowledge on this topic. In our study, we modelled the course of the chlamydial infection in human primary gastrointestinal (GI) epithelial cells originating from patient-derived organoids.

Intracellular Staphylococcus aureus employs the cysteine protease staphopain A to induce host cell death in epithelial cells.

Staphylococcus aureus is a major human pathogen, which can invade and survive in non-professional and professional phagocytes. Uptake by host cells is thought to contribute to pathogenicity and persistence of the bacterium. Upon internalization by epithelial cells, cytotoxic S.

α-Toxin Induces Acid Sphingomyelinase Release From a Human Endothelial Cell Line.

() is well known to express a plethora of toxins of which the pore-forming hemolysin A (α-toxin) is the best-studied cytolysin. Pore-forming toxins (PFT) permeabilize host membranes during infection thereby causing concentration-dependent effects in host cell membranes ranging from disordered ion fluxes to cytolysis. Host cells possess defense mechanisms against PFT attack, resulting in endocytosis of the breached membrane area and delivery of repair vesicles to the insulted plasma membrane as well as a concurrent release of membrane repair enzymes.

Intracellular persistence of in endothelial cells is promoted by the absence of phenol-soluble modulins.

A large proportion of clinical isolates that carry an inactive Agr system are associated with persistent infection that is difficult to treat. Once is inside the bloodstream, it can cross the endothelial barrier and invade almost every organ in the human body. Endothelial cells can either be lysed by this pathogen or they serve as a niche for its intracellular long-term survival.

The Expandables: Cracking the Staphylococcal Cell Wall for Expansion Microscopy.

Expansion Microscopy (ExM) is a novel tool improving the resolution of fluorescence microscopy by linking the sample into a hydrogel that gets physically expanded in water. Previously, we have used ExM to visualize the intracellular Gram-negative pathogens , , and . Gram-positive bacteria have a rigid and thick cell wall that impedes classic expansion strategies.

A Role of Sphingosine in the Intracellular Survival of .

Obligate human pathogenic are the second most frequent bacterial cause of sexually transmitted diseases. These bacteria invade different mucosal tissues and occasionally disseminate into the bloodstream. Invasion into epithelial cells requires the activation of host cell receptors by the formation of ceramide-rich platforms.

Staphylococcus aureus Exploits a Non-ribosomal Cyclic Dipeptide to Modulate Survival within Epithelial Cells and Phagocytes.

Community-acquired (CA) Staphylococcus aureus cause various diseases even in healthy individuals. Enhanced virulence of CA-strains is partly attributed to increased production of toxins such as phenol-soluble modulins (PSM). The pathogen is internalized efficiently by mammalian host cells and intracellular S.

Natural mutations in a Staphylococcus aureus virulence regulator attenuate cytotoxicity but permit bacteremia and abscess formation.

Staphylococcus aureus is a major bacterial pathogen, which causes severe blood and tissue infections that frequently emerge by autoinfection with asymptomatically carried nose and skin populations. However, recent studies report that bloodstream isolates differ systematically from those found in the nose and skin, exhibiting reduced toxicity toward leukocytes. In two patients, an attenuated toxicity bloodstream infection evolved from an asymptomatically carried high-toxicity nasal strain by loss-of-function mutations in the gene encoding the transcription factor repressor of surface proteins (rsp).

A novel point mutation promotes growth phase-dependent daptomycin tolerance in Staphylococcus aureus.

Recalcitrance of genetically susceptible bacteria to antibiotic killing is a hallmark of bacterial drug tolerance. This phenomenon is prevalent in biofilms, persisters, and also planktonic cells and is associated with chronic or relapsing infections with pathogens such as Staphylococcus aureus. Here we report the in vitro evolution of an S.

Cytoplasmic replication of Staphylococcus aureus upon phagosomal escape triggered by phenol-soluble modulin α.

Staphylococcus aureus is a Gram-positive human pathogen that is readily internalized by professional phagocytes such as macrophages and neutrophils but also by non-professional phagocytes such as epithelial or endothelial cells. Intracellular bacteria have been proposed to play a role in evasion of the innate immune system and may also lead to dissemination within migrating phagocytes. Further, S.

Expression of δ-toxin by Staphylococcus aureus mediates escape from phago-endosomes of human epithelial and endothelial cells in the presence of β-toxin.

Staphylococcus aureus is able to invade non-professional phagocytes by interaction of staphylococcal adhesins with extracellular proteins of mammalian cells and eventually resides in acidified phago-endosomes. Some staphylococcal strains have been shown to subsequently escape from this compartment. A functional agr quorum-sensing system is needed for phagosomal escape.

Codon-improved fluorescent proteins in investigation of Staphylococcus aureus host pathogen interactions.

Here we present the use of three fluorescent proteins in Staphylococcus aureus, Cerulean, PA-GFP, and mRFPmars. All molecules have an improved codon adaptation for expression in the A + T rich organisms and extend the fluorescent protein portfolio in staphylococcal research.

Staphylococcal alpha-toxin is not sufficient to mediate escape from phagolysosomes in upper-airway epithelial cells.

Intracellular Staphylococcus aureus has been implicated in the establishment of chronic infections. It is therefore imperative to understand by what means S. aureus is able to survive within cells.

Potential protective role of apoprotein J (clusterin) in atherogenesis: binding to enzymatically modified low-density lipoprotein reduces fatty acid-mediated cytotoxicity.

Following entrapment in the arterial intima, low-density lipoprotein (LDL) can be modified by hydrolytic enzymes to yield a lipoprotein derivative that binds C-reactive protein, activates complement, and is rapidly taken up by monocytes/macrophages. Free fatty acids contained in enzymatically modified LDL (E-LDL) render the lipoprotein cytotoxic due to their capacity to trigger programmed cell death. Apoprotein J (ApoJ) alias clusterin is a multifunctional glycoprotein with cytoprotective and anti-inflammatory properties.

Enzymatic modification of low-density lipoprotein in the arterial wall: a new role for plasmin and matrix metalloproteinases in atherogenesis.

Objective: Functionally interactive proteases of the plasminogen/plasmin and the matrix metalloproteinase (MMP) system degrade and reorganize the extracellular matrix of the vessel wall in atherosclerosis. Here we investigated whether such proteases are able to confer atherogenic properties onto low density lipoprotein by nonoxidative modification.

Methods And Results: Similar to the recently described enzymatically-modified low-density lipoprotein (E-LDL), native LDL exposed to plasmin or matrix MMP-2 or MMP-9 and cholesterylester-hydrolase (CEH) showed extensive deesterification, with ratios of free cholesterol to total cholesterol rising to 0.

Possible protective role for C-reactive protein in atherogenesis: complement activation by modified lipoproteins halts before detrimental terminal sequence.

Background: Previous work indicated that enzymatically remodeled LDL (E-LDL) might activate complement in atherosclerotic lesions via a C-reactive protein (CRP)-dependent and CRP-independent pathway. We sought to substantiate this contention and determine whether both pathways drive the sequence to completion.

Methods And Results: E-LDL was prepared by sequential treatment of LDL with a protease and cholesteryl esterase.

Enzymatically modified LDL induces cathepsin H in human monocytes: potential relevance in early atherogenesis.

Objective: Modification with proteases and cholesterylesterase transforms LDL to a moiety that resembles lipoproteins isolated from atherosclerotic lesions and possesses atherogenic properties. To identify changes in monocyte-derived foam cells laden with enzymatically modified LDL (E-LDL), we compared patterns of the most abundant transcripts in these cells after incubation with LDL or E-LDL.

Methods And Results: Serial analyses of gene expression (SAGE) libraries were constructed from human monocytes after treatment with LDL or E-LDL.

AP-1 in Toxoplasma gondii mediates biogenesis of the rhoptry secretory organelle from a post-Golgi compartment.

We have previously demonstrated that Toxoplasma gondii has a tyrosine-based sorting system, which mediates protein targeting to the lysosome-like rhoptry secretory organelle. We now show that rhoptry protein targeting is also dependent on a dileucine motif and occurs from a post-Golgi endocytic organelle to mature rhoptries in an adaptin-dependent fashion. The T.