Biology subjects

De Jesus, M.

Publications and source records attributed to De Jesus, M..

5 recordsLinked to original sources

bioRxiv2021

Mechanically active integrins direct cytotoxic secretion at the immune synapse

The secretory output of cell-cell interfaces must be tightly controlled in space and time to ensure functional efficacy. This is particularly true for the cytotoxic immune synapse (IS), the stereotyped junction formed between a cytotoxic lymphocyte and the infected or transformed target cell it aims to destroy1. Cytotoxic lymphocytes kill their targets by channeling a mixture of granzyme proteases and the pore forming protein perforin directly into the IS2, 3. The synaptic secretion of these toxic molecules constrains their deleterious effects to the target cell alone, thereby protecting innocent bystander cells in the surrounding tissue from collateral damage. Despite the importance of this process for immune specificity, the molecular and cellular mechanisms that establish secretory sites within the IS remain poorly understood. Here, we identified an essential role for integrin mechanotransduction in cytotoxic secretion using a combination of single cell biophysical measurements, ligand micropatterning, and functional assays. Upon ligand-binding, the L{beta}2 integrin LFA-1 functioned as a spatial cue, attracting lytic granules containing perforin and granzyme and inducing their fusion at closely adjacent sites within the synaptic membrane. LFA-1 molecules were subjected to pulling forces within these secretory domains, and genetic or pharmacological suppression of these forces abrogated cytotoxicity. We conclude that lymphocytes employ an integrin-dependent mechanical checkpoint to enhance both the potency and the security of their cytotoxic output.

immunology↗

bioRxiv2021

Candida auris is rendered non-viable by medium-chain fatty acids

The medium-chain fatty acids, octanoic and decanoic acid, found in coconut oil, were fungistatic and decanoic acid was fungicidal against a panel of Candida auris strains, during both planktonic and biofilm growth. The strains were from all four major geographic clades, and some were resistant to several classes of antifungal drugs. These compounds are safe, natural products and could provide a new strategy for skin decolonization and environmental decontamination.

microbiology↗

bioRxiv2019

Impact of Candida auris infection in a neutropenic murine model

Candida auris has become a global public health threat due to its multidrug resistance and persistence in hospital and nursing home settings. Although a skin colonizer, C. auris can cause fatal bloodstream infections and most patients succumb to multi-organ failure. Currently, there are limited animal models to study the progression of C. auris infection. Here we compare two murine models of neutrophil depletion using monoclonal antibodies 1A8, anti-Ly6G+ and RB6-8C5 anti-Ly6G+-Ly6C+. We also compare inoculums of 107 and 108 as well as the intravenous and gavage routes of infection. The results reveal that neutrophil depletion in BALB/c mice is sustained long-term with the 1A8 antibody and short-term with RB6-8C5. Target organs were kidney, heart and brain as these had the highest organ fungal burden in neutrophil depleted and to some extent in infected control mice. We found that C. auris is shed in urine and feces for neutrophil depleted mice. The gavage model is not an ideal route as dissemination was not detected. Eight days post C. auris infection all surviving mice display a unique behavioral phenotype characterized by torticollis and tail spin that progresses to head bobbing and body curling like phenotype by day 22, that continues to persist even 104 days post infection. Lastly, we found C. auris remains in tissues of infected control mice, 34 plus days post infection suggesting that C. auris stays present in the host without causing disease but becomes opportunistic upon a change in the hosts immune status such as neutrophil depletion.

microbiology↗

bioRxiv2019

Setting off the Alarms: Candida albicans Elicits Pro-Inflammatory Differential Gene Expression in Intestinal Peyer’s Patches

Candida albicans has been associated with a number of human diseases that pertain to the gastrointestinal (GI) tract. However, the details of how gut-associated lymphoid tissues (GALT) such as Peyers patches (PPs) in the small intestine play a role in immune surveillance and microbial differentiation, and what mechanisms PP use to protect the mucosal barrier in response to fungal organisms such as C. albicans, are still unclear. We particularly focus on PPs as they are the immune sensors and inductive sites of the gut that influence inflammation and tolerance. We have previously demonstrated that CD11c+ phagocytes located in the sub-epithelial dome (SED) within PPs sample C. albicans. To gain insight on how specific cells within PPs sense and respond to the sampling of fungi, we gavaged mice with C. albicans strains ATCC 18804 and SC5314 as well as Saccharomyces cerevisiae. We measured the differential gene expression of sorted CD45+ B220+ B-cells, CD3+ T-cells, and CD11c+ DCs within the first 24 hrs post-gavage using nanostring nCounter(R) technology. The results reveal that at 24 hrs, PP phagocytes were the cell type that displayed differential gene expression. These phagocytes were both able to sample C. albicans and able to discriminate between strains. In particular, strain ATCC 18804 upregulated fungal specific pro-inflammatory genes in CD11c+ phagocytes pertaining to innate and adaptive immune responses. Interestingly, PP CD11c+ phagocytes differentially expressed genes in response to C. albicans that were important in the protection of the mucosal barrier. These results highlight that the mucosal barrier not only responds to C. albicans, but also aids in the protection of the host.\n\nImportanceThe specific gene expression changes within PPs that send the warning signals when encountering fungi, and how PPs can discriminate between innocuous S. cerevisiae or different strains of C. albicans during early stages of sampling, have not been elucidated. Here we show that within the first 24 hours of sampling, CD11c+ phagocytes were not only important in sampling, but they were the cell type that exhibited clear differential gene expression. These differentially expressed genes play important dual roles in inflammation, chemotaxis, and fungal specific recognition, as well as maintaining homeostasis and protection of the mucosal barrier. Using nanostring technology, we were also able to demonstrate that PPs can distinguish between different strains of C. albicans and can \"set off the alarms\" when necessary.

microbiology↗

bioRxiv2018

Assessment of Environmental and Occupational Exposure while Working with Candida auris a Multidrug Resistant (MDR) Fungus in the Animal Facility.

In less than a decade since its identification in 2009, the emerging fungal pathogen Candida auris has become a major public health threat due to its multidrug resistant (MDR) phenotype, high transmissibility, and high mortality. Unlike any other Candida species, C. auris has acquired high levels of resistance to an already limited arsenal of antifungals. As an emerging pathogen, there are currently a limited number of documented murine models of C. auris infection. These animal models use inoculums as high as 107-108 cells per mouse, and the environmental and occupational exposure of working with these models has not been clearly defined. Using real-time quantitative PCR and culture, we monitored the animal holding room as well as the procedure room for up to six months while working with an intravenous model of C. auris infection. This study determined that shedding of the organism is dose-dependent, as detectable levels of C. auris were detected in the cage bedding when mice were infected with 107 and 108 cells, but not with doses of 105 and 106 cells. Autoclaving bedding in closed micro-isolator cages was found to be an effective way to minimize exposure to animal caretakers. We found that tissue necropsies of infected mice were also an important source of potential source exposure to C. auris. To mitigate these potential exposures, we implemented a rigorous \"buddy system\" workflow and a disinfection protocol that uses 10% bleach followed by 70% ethanol and can be used in any animal facility when using small animal models of C. auris infection.

microbiology↗