Kinetics of severe dengue virus infection and development of gut pathology in mice.

IMPORTANCE: Dengue virus, an arbovirus, causes an estimated 100 million symptomatic infections annually and is an increasing threat as the mosquito range expands with climate change. Dengue epidemics are a substantial strain on local economies and health infrastructure, and an understanding of what drives severe disease may enable treatments to help reduce hospitalizations. Factors exacerbating dengue disease are debated, but gut-related symptoms are much more frequent in severe than mild cases. Using mouse models of dengue infection, we have shown that inflammation and damage are earlier and more severe in the gut than in other tissues. Additionally, we observed impairment of the gut mucus layer and propose that breakdown of the barrier function exacerbates inflammation and promotes severe dengue disease. This idea is supported by recent data from human patients showing elevated bacteria-derived molecules in dengue patient serum. Therapies aiming to maintain gut integrity may help to abrogate severe dengue disease.

SARS-CoV-2 drives NLRP3 inflammasome activation in human microglia through spike protein.

Coronavirus disease-2019 (COVID-19) is primarily a respiratory disease, however, an increasing number of reports indicate that SARS-CoV-2 infection can also cause severe neurological manifestations, including precipitating cases of probable Parkinson's disease. As microglial NLRP3 inflammasome activation is a major driver of neurodegeneration, here we interrogated whether SARS-CoV-2 can promote microglial NLRP3 inflammasome activation. Using SARS-CoV-2 infection of transgenic mice expressing human angiotensin-converting enzyme 2 (hACE2) as a COVID-19 pre-clinical model, we established the presence of virus in the brain together with microglial activation and NLRP3 inflammasome upregulation in comparison to uninfected mice. Next, utilising a model of human monocyte-derived microglia, we identified that SARS-CoV-2 isolates can bind and enter human microglia in the absence of viral replication. This interaction of virus and microglia directly induced robust inflammasome activation, even in the absence of another priming signal. Mechanistically, we demonstrated that purified SARS-CoV-2 spike glycoprotein activated the NLRP3 inflammasome in LPS-primed microglia, in a ACE2-dependent manner. Spike protein also could prime the inflammasome in microglia through NF-κB signalling, allowing for activation through either ATP, nigericin or α-synuclein. Notably, SARS-CoV-2 and spike protein-mediated microglial inflammasome activation was significantly enhanced in the presence of α-synuclein fibrils and was entirely ablated by NLRP3-inhibition. Finally, we demonstrate SARS-CoV-2 infected hACE2 mice treated orally post-infection with the NLRP3 inhibitory drug MCC950, have significantly reduced microglial inflammasome activation, and increased survival in comparison with untreated SARS-CoV-2 infected mice. These results support a possible mechanism of microglial innate immune activation by SARS-CoV-2, which could explain the increased vulnerability to developing neurological symptoms akin to Parkinson's disease in COVID-19 infected individuals, and a potential therapeutic avenue for intervention.

Disección coronaria espontánea posterior a envenenamiento por escorpión / Spontaneous coronary artery dissection following scorpion poisoning

Resumen Hombre de 44 años que acude al servicio de urgencias posterior a picadura de escorpión. Presentaba parestesias, dolor toracoabdominal y náuseas. Desde el momento del ingreso presentó dolor torácico atípico, dolor abdominal epigástrico de intensidad leve, asociado a náuseas. Se realizó electrocardiograma que no evidenció alteraciones. La troponina fue elevada, por lo que se llevó a cuidado intensivo y se inició manejo antiisquémico, corroborando posteriormente en la angiografía una disección coronaria tipo 1 en el ramus intermedio como causante de su evento coronario. El paciente recibió un vial de suero antiescorpiónico en primer nivel de atención y posteriormente se indicó manejo con betabloqueante, antiagregación con ácido acetilsalicílico y clopidogrel, con disminución progresiva de sus síntomas. Es egresado asintomático. Se reporta un caso de infarto agudo de miocardio tipo 2 por disección coronaria posterior a una picadura de escorpión, del cual no hay casos reportados previamente en el mundo.

Abstract A 44-year-old man was admitted to the emergency department after a scorpion sting. He presented paresthesia, thoracoabdominal pain and nausea. From the moment of admission, he presented atypical chest pain, epigastric abdominal pain of mild intensity, associated with nausea. An ECG was taken that did not show alterations, troponin was elevated, he was admitted to intensive care unit, management was initiated, subsequently corroborating in the angiography, a type 1 coronary artery dissection in the intermediate ramus as the cause of coronary event. The patient received a vial of antiscorpionic serum in the first level of care, later treatment with beta-blocker, antiaggregation with acetylsalicylic acid and clopidogrel was indicated, with progressive reduction of his symptoms. He is an asymptomatic graduate. A case of type 2 acute myocardial infarction due to coronary dissection after a scorpion sting is reported, there are no previously reported cases in the world.

Cell-Extrinsic Differentiation Block Mediated by EphA3 in Pre-Leukaemic Thymus Contributes to Disease Progression.

We recently characterised the NUP98-HOXD13 (NHD13) mouse as a model of T-cell pre-leukaemia, featuring thymocytes that can engraft in recipient animals and progress to T-cell acute lymphoblastic leukaemia (T-ALL). However, loss of this engraftment ability by deletion of Lyl1 did not result in any loss of leukemogenesis activity. In the present study, we observe that NHD13 thymocytes overexpress EPHA3, and we characterise thymocyte behaviour in NHD13 mice with deletion of EphA3, which show a markedly reduced incidence of T-ALL. Deletion of EphA3 from the NHD13 mice does not prevent the abnormal accumulation or transplantation ability of these thymocytes. However, upon transplantation, these cells are unable to block the normal progression of recipient wild type (WT) progenitor cells through the normal developmental pathway. This is in contrast to the EphA3+/+ NHD13 thymocytes, which block the progression of incoming WT progenitors past the DN1 stage. Therefore, EphA3 is not critical for classical self-renewal, but is essential for mediating an interaction between the abnormally self-renewing cells and healthy progenitors-an interaction that results in a failure of the healthy cells to differentiate normally. We speculate that this may orchestrate a loss of healthy cell competition, which in itself has been demonstrated to be oncogenic, and that this may explain the decrease in T-ALL incidence in the absence of EphA3. We suggest that pre-leukaemic self-renewal in this model is a complex interplay of cell-intrinsic and -extrinsic factors, and that multiple redundant pathways to leukaemogenesis are active.

Tea tree oil extract causes mitochondrial superoxide production and apoptosis as an anticancer agent, promoting tumor infiltrating neutrophils cytotoxic for breast cancer to induce tumor regression.

The antitumor activity of the tea tree oil (TTO) derived product, Melaleuca Alternifolia Concentrate (MAC) was characterized mechanistically at the molecular and cellular level. MAC was analyzed for its anticancer activity against human prostate (LNCaP) and breast (MCF-7) cancer cell lines growing in vitro. MAC (0.02-0.06% v/v) dose-dependently induced the intrinsic (mitochondrial) apoptotic pathway in both the LNCaP and MCF-7 cell lines, involving increased mitochondrial superoxide production, loss of mitochondrial membrane potential (MMP), caspase 3/7 activation, as well as the presence of TUNEL+ and cleaved-PARP+ cell populations. At concentrations of 0.01-0.04% v/v, MAC caused cell cycle arrest in the G0/1-phase, as well as autophagy. The in vivo anticancer actions of MAC were examined as a treatment in the FVB/N c-Neu murine model for spontaneously arising breast cancers. Intratumoral MAC injections (1-4% v/v) significantly suppressed tumor progression in a dose-dependent manner and was associated with greater levels of tumor infiltrating neutrophils exhibiting anticancer cytotoxic activity. Induction of breast cancer cell death by MAC via the mitochondrial apoptotic pathway was also replicated occurring in tumors treated in vivo. In conclusion, our data highlights the potential for the Melaleuca-derived MAC product inducing anticancer neutrophil influx, supporting its application as a novel therapeutic agent.

Manipulation of epithelial cell death pathways by Shigella.

Shigella, a major cause of bacterial dysentery, knows when it is not wanted. To generate and maintain its niche within host cells, this unwelcome guest injects several dozen virulence factors via a type 3 secretion system (T3SS). In this issue, Ashida et al (2020) have elucidated the role of two such factors from Shigella flexneri-OspC1 and OspD3-that together counteract apoptotic and necroptotic death pathways in colonised epithelial cells. As a result, Shigella can replicate to high levels within the colonic epithelium, leading to the substantial epithelial damage in shigellosis and efficient bacterial release for faecal transmission.

Toxin-neutralizing antibodies elicited by naturally acquired cutaneous anthrax are elevated following severe disease and appear to target conformational epitopes.

Understanding immune responses to native antigens in response to natural infections can lead to improved approaches to vaccination. This study sought to characterize the humoral immune response to anthrax toxin components, capsule and spore antigens in individuals (n = 46) from the Kayseri and Malatya regions of Turkey who had recovered from mild or severe forms of cutaneous anthrax infection, compared to regional healthy controls (n = 20). IgG antibodies to each toxin component, the poly-γ-D-glutamic acid capsule, the Bacillus collagen-like protein of anthracis (BclA) spore antigen, and the spore carbohydrate anthrose, were detected in the cases, with anthrax toxin neutralization and responses to Protective Antigen (PA) and Lethal Factor (LF) being higher following severe forms of the disease. Significant correlative relationships among responses to PA, LF, Edema Factor (EF) and capsule were observed among the cases. Though some regional control sera exhibited binding to a subset of the tested antigens, these samples did not neutralize anthrax toxins and lacked correlative relationships among antigen binding specificities observed in the cases. Comparison of serum binding to overlapping decapeptides covering the entire length of PA, LF and EF proteins in 26 cases compared to 8 regional controls revealed that anthrax toxin-neutralizing antibody responses elicited following natural cutaneous anthrax infection are directed to conformational epitopes. These studies support the concept of vaccination approaches that preserve conformational epitopes.

Tinea gladiatorum due to Trichophyton tonsurans in a school wrestling team in Mexico: A case series.

BACKGROUND AND PURPOSE: Tinea gladiatorum is a type of dermatophytosis that occurs in combat athletes, such as wrestlers and judo fighters, as a result of Trichophyton species. Herein, we aimed to present a small outbreak of tinea gladiatorum in a high school in Mexico. MATERIALS AND METHODS: Seven individuals belonging to the school fighting team were mycologically studied with direct examinations and cultures. In four cases, T. tonsurans was isolated and identified by morphological and proteomic methods (Matrix-assisted laser desorption/ionization- time-of-flight mass spectrometry). Out of the four subjects, two cases had clinical lesions presented as tinea corporis, and two cases were healthy carriers. Trichophyton tonsurans was also isolated from one of the four training mats (25%). All positive patients were treated with systemic or topical antifungals and achieved clinical and mycological cure. CONCLUSION: We report the first outbreak of tinea gladiatorum caused by T. tonsurans among a group of high school wrestlers in Mexico.

The NUP98-HOXD13 fusion oncogene induces thymocyte self-renewal via Lmo2/Lyl1.

T cell acute lymphoblastic leukaemia (T-ALL) cases include subfamilies that overexpress the TAL1/LMO, TLX1/3 and HOXA transcription factor oncogenes. While it has been shown that TAL1/LMO transcription factors induce self-renewal of thymocytes, whether this is true for other transcription factor oncogenes is unknown. To address this, we have studied NUP98-HOXD13-transgenic (NHD13-Tg) mice, which overexpress HOXA transcription factors throughout haematopoiesis and develop both myelodysplastic syndrome (MDS) progressing to acute myeloid leukaemia (AML) as well as T-ALL. We find that thymocytes from preleukaemic NHD13-Tg mice can serially transplant, demonstrating that they have self-renewal capacity. Transcriptome analysis shows that NHD13-Tg thymocytes exhibit a stem cell-like transcriptional programme closely resembling that induced by Lmo2, including Lmo2 itself and its critical cofactor Lyl1. To determine whether Lmo2/Lyl1 are required for NHD13-induced thymocyte self-renewal, NHD13-Tg mice were crossed with Lyl1 knockout mice. This showed that Lyl1 is essential for expression of the stem cell-like gene expression programme in thymocytes and self-renewal. Surprisingly however, NHD13 transgenic mice lacking Lyl1 showed accelerated T-ALL and absence of transformation to AML, associated with a loss of multipotent progenitors in the bone marrow. Thus multiple T cell oncogenes induce thymocyte self-renewal via Lmo2/Lyl1; however, NHD13 can also promote T-ALL via an alternative pathway.

The in vitro and in vivo antiviral properties of combined monoterpene alcohols against West Nile virus infection.

West Nile Virus (WNV) is a mosquito-borne flavivirus that can cause neuroinvasive disease in humans and animals for which no therapies are currently available. We studied an established combination of monoterpene alcohols (CMA) derived from Melaleuca alternifolia, against WNV infection. The in vitro results show that CMA exhibits virucidal activity, as well as reduces the viral titres and percentage of infected cells. The antiviral mechanism of action of CMA was studied. We found that CMA did not alter the intracellular pH, neither induced apoptosis, but did induce cell cycle arrest in the G0/G1-phase although that was not the antiviral mechanism. Furthermore, we tested CMA in vivo using IRF 3(-)(/)(-)/7(-/-)mice and it was found that CMA treatment significantly delayed morbidity due to WNV infection, reduced the loss of body weight and reduced the viral titres in brain. These findings suggest that CMA could be a therapeutic agent against WNV infection.

Perfil epidemiológico de la intoxicación con burundanga en la clínica Uribe Cualla S.A. de Bogotá, D.C / Epidemic profile of the intoxication with burundanga in the Clínica Uribe Cualla of Bogotá, D. C

Introducción: Las intoxicaciones con intención delictiva constituyen un motivo frecuente de consulta en urgencias. Objetivo: Presentar el perfil epidemiológico de la intoxicación con burundanga y nueva burundanga en un centro de referencia de Bogotá. Material y métodos: Se hizo una revisión de las historias clínicas de los pacientes que consultaron a la clínica Uribe Cualla SA. entre Enero de 1998 y Julio de 2004. Resultados: Se evaluaron las historias de 860 pacientes, se encontró una mayor frecuencia de pacientes en edad reproductiva (20-50 años), del sexo masculino 79,1 por ciento, en quienes el móvil más frecuente fue el robo 67,44 por ciento. Conclusión: Los datos obtenidos en el estudio concuerdan con los de otras instituciones colombianas que reciben esta clase de pacientes. La Clínica Guillermo Uribe Cualla es un centro de referencia para patologías toxicológicas. Conocer las características de los pacientes atendidos en esta Institución permite una buena aproximación al perfil epidemiológico de estas intoxicaciones en nuestro país y con base en estos datos diseñar estudios que permitan estudiar y mejorar los problemas que traen consigo la intoxicación con estas sustancias y sus consecuencias reales sobre la salud de los Colombianos