Biology subjects

Stienstra, Y.

Publications and source records attributed to Stienstra, Y..

3 recordsLinked to original sources

bioRxiv2021

Moxidectin and ivermectin inhibit SARS-CoV-2 replication in Vero E6 cells but not in human primary airway epithelium cells

Antiviral therapies are urgently needed to treat and limit the development of severe COVID-19 disease. Ivermectin, a broad-spectrum anti-parasitic agent, has been shown to have anti-SARS-CoV-2 activity in Vero cells at a concentration of 5 {micro}M. These in vitro results triggered the investigation of ivermectin as a treatment option to alleviate COVID-19 disease. In April 2021, the World Health Organization stated, however, the following: "the current evidence on the use of ivermectin to treat COVID-19 patients is inconclusive". It is speculated that the in vivo concentration of ivermectin is too low to exert a strong antiviral effect. Here, we performed a head-to head comparison of the antiviral activity of ivermectin and a structurally related, but metabolically more stable, moxidectin in multiple in vitro models of SARS-CoV-2 infection, including physiologically relevant human respiratory epithelial cells. Both moxidectin and ivermectin exhibited antiviral activity in Vero E6 cells. Subsequent experiments revealed that the compounds predominantly act on a step after virus cell entry. Surprisingly, however, in human airway-derived cell models, moxidectin and ivermectin failed to inhibit SARS-CoV-2 infection, even at a concentration of 10 {micro}M. These disappointing results calls for a word of caution in the interpretation of anti-SARS-CoV-2 activity of drugs solely based on Vero cells. Altogether, these findings suggest that, even by using a high-dose regimen of ivermectin or switching to another drug in the same class are unlikely to be useful for treatment against SARS-CoV-2 in humans.

microbiology↗

bioRxiv2018

Bioluminscent Mycobacterium ulcerans, a tool to study host-pathogen interactions in a murine tail model of Buruli ulcer

Buruli ulcer is a neglected tropical disease caused by infection with Mycobacterium ulcerans. In this study we used a previously reported strain of M. ulcerans, genetically engineered to constitutively produce bioluminescence, to follow the progression of Buruli ulcer in mice using an in-vivo imaging (IVIS(R)) system. We aimed to characterize a mouse tail infection model for pathogenesis, as well as for pre-clinical vaccine and drug development research for Buruli ulcer. Immune parameters, such as antibody titers and cytokine levels, were determined throughout the course of the infection and histology specimens were examined for comparison with human pathology. Nine out of ten (90%) BALB/c mice infected subcutaneously with 105 M. ulcerans JKD8049 (containing pMV306 hsp16+luxG13) exhibited light emission from the site of infection over the course of the experiment indicating M. ulcerans growth in-vivo. Five out of ten (50%) animals developed clinical signs of disease. Antibody titers were overall low and their onset was late, as measured by responses to both heterogenous (bacterial whole cell lysate) and single antigen (Hsp18) targets. IFN-{gamma}, and IL-10 are reported to play a vital role in host control of Buruli ulcer and these cytokines were elevated in animals with pathology. For mice with advanced pathology, histology revealed clusters of acid-fast bacilli within subcutaneous tissue 300-400 m beneath the epidermis of the tail, with macrophage infiltration and granuloma-formation resembling human Buruli ulcer. This study has shown the utility of using bioluminescent M. ulcerans and IVIS(R) in a mouse tail infection model to study Buruli ulcer infection.\n\nAuthor summaryBuruli ulcer is one of the so called neglected tropical diseases. It is an infectious disease, mainly occurring in West Africa but also in Australia. It manifests as skin lesion and ulcer. Up to date, the way of transmission is inadequately understood. Also, there is no vaccine to protect against the disease. Buruli ulcer is treatable with a course of antibiotics that need to be given for the duration of two months. More laboratory research is needed to elucidate the mechanism of transmission, develop a vaccine and improve and shorten antibiotic therapy. For this, animal (mouse) models of disease are used. The aim of this study was to refine and improve the mouse tail infection model of Buruli ulcer. For this, we used a genetically modified Mycobacterium ulcerans strain that emits light. After infection of animals, light emitted from the bacteria was read out with an in-vivo imaging (IVIS) camera. This allowed us to monitor the location of bacteria in the living animal over time without the need to kill the animal. We also measured parameters of the immune system such as antibodies and cytokines as a baseline for future studies into immunology, vaccine development and pathology of Buruli ulcer. We successfully improved and characterized the mouse tail infection model in Buruli ulcer with the use of modern technology using light emitting bacteria and the IVIS camera.

microbiology↗

bioRxiv2018

High-dose rifamycins enable shorter oral treatment in a murine model of Mycobacterium ulcerans disease

Buruli ulcer (BU), caused by Mycobacterium ulcerans, is a neglected tropical skin and soft tissue infection that is associated with disability and social stigma. The mainstay of BU treatment is an eight-week course of 10 mg/kg rifampin (RIF) and 150 mg/kg streptomycin (STR). Recently, the injectable STR has been shown to be replaceable with oral clarithromycin (CLR) for smaller lesions for the last four weeks of treatment. A shorter, all-oral, highly efficient regimen for BU is needed, as the long treatment duration and indirect costs currently burden patients and health systems. Increasing the dose of RIF or replacing it with the more potent rifamycin drug rifapentine (RPT) could provide such a regimen. Here, we performed a dose-ranging experiment of RIF and RPT in combination with CLR over four weeks of treatment in a mouse model of M. ulcerans disease. A clear dose-dependent effect of RIF on both clinical and microbiological outcomes was found, with no ceiling effect observed with tested doses up to 40 mg/kg. RPT-containing regimens were more effective on M. ulcerans. All RPT-containing regimens achieved culture negativity after only four weeks while only the regimen with the highest RIF dose (40 mg/kg) did so. We conclude that there is dose-dependent efficacy of both RIF and RPT and that a ceiling effect is not reached with the current standard regimen used in the clinic. A regimen based on higher rifamycin doses that are currently being evaluated against tuberculosis in clinical trials could shorten and improve therapy of Buruli ulcer.

microbiology↗