Although mainly causing a respiratory syndrome, numerous neurological symptoms have been identified following of SARS-CoV-2 infection. However, how the virus affects the brain and how the mutations ...carried by the different variants modulate those neurological symptoms remain unclear.
We used primary human pericytes, foetal astrocytes, endothelial cells and a microglial cell line to investigate the effect of several SARS-CoV-2 variants of concern or interest on their functional activities. Cells and a 3D blood-brain barrier model were infected with the wild-type form of SARS-CoV-2, Alpha, Beta, Delta, Eta, or Omicron (BA.1) variants at various MOI. Cells and supernatant were used to evaluate cell susceptibility to the virus using a microscopic assay as well as effects of infection on (i) cell metabolic activity using a colorimetric MTS assay; (ii) viral cytopathogenicity using the xCELLigence system; (iii) extracellular glutamate concentration by fluorometric assay; and (iv) modulation of blood-brain barrier permeability.
We demonstrate that productive infection of brain cells is SARS-CoV-2 variant dependent and that all the variants induce stress to CNS cells. The wild-type virus was cytopathic to all cell types except astrocytes, whilst Alpha and Beta variants were only cytopathic for pericytes, and the Omicron variant cytopathic for endothelial cells and pericytes. Lastly wild-type virus increases blood-brain barrier permeability and all variants, except Beta, modulate extracellular glutamate concentration, which can lead to excitotoxicity or altered neurotransmission.
These results suggest that SARS-CoV-2 is neurotropic, with deleterious consequences for the blood-brain barrier integrity and central nervous system cells, which could underlie neurological disorders following SARS-CoV-2 infection.
In high-burden settings, case fatality rates are reported to be between 11% and 32% in hospitalized patients with HIV-associated tuberculosis, yet the underlying causes of mortality remain poorly ...characterized. Understanding causes of mortality could inform the development of novel management strategies to improve survival. We aimed to assess clinical and microbiologic determinants of mortality and to characterize the pathophysiological processes underlying death by evaluating host soluble inflammatory mediators and determined the relationship between these mediators and death as well as biomarkers of disseminated tuberculosis.
Adult patients with HIV hospitalized with a new diagnosis of HIV-associated tuberculosis were enrolled in Cape Town between 2014 and 2016. Detailed tuberculosis diagnostic testing was performed. Biomarkers of tuberculosis dissemination and host soluble inflammatory mediators at baseline were assessed. Of 682 enrolled participants, 576 with tuberculosis (487/576, 84.5% microbiologically confirmed) were included in analyses. The median age was 37 years (IQR = 31-43), 51.2% were female, and the patients had advanced HIV with a median cluster of differentiation 4 (CD4) count of 58 cells/L (IQR = 21-120) and a median HIV viral load of 5.1 log10 copies/mL (IQR = 3.3-5.7). Antituberculosis therapy was initiated in 566/576 (98.3%) and 487/576 (84.5%) started therapy within 48 hours of enrolment. Twelve-week mortality was 124/576 (21.5%), with 46/124 (37.1%) deaths occurring within 7 days of enrolment. Clinical and microbiologic determinants of mortality included disseminated tuberculosis (positive urine lipoarabinomannan LAM, urine Xpert MTB/RIF, or tuberculosis blood culture in 79.6% of deaths versus 60.7% of survivors, p = 0.001), sepsis syndrome (high lactate in 50.8% of deaths versus 28.9% of survivors, p < 0.001), and rifampicin-resistant tuberculosis (16.9% of deaths versus 7.2% of survivors, p = 0.002). Using non-supervised two-way hierarchical cluster and principal components analyses, we describe an immune profile dominated by mediators of the innate immune system and chemotactic signaling (interleukin-1 receptor antagonist IL-1Ra, IL-6, IL-8, macrophage inflammatory protein-1 beta MIP-1β/C-C motif chemokine ligand 4 CCL4, interferon gamma-induced protein-10 IP-10/C-X-C motif chemokine ligand 10 CXCL10, MIP-1 alpha MIP-1α/CCL3), which segregated participants who died from those who survived. This immune profile was associated with mortality in a Cox proportional hazards model (adjusted hazard ratio aHR = 2.2, 95%CI = 1.9-2.7, p < 0.001) and with detection of biomarkers of disseminated tuberculosis. Clinicians attributing causes of death identified tuberculosis as a cause or one of the major causes of death in 89.5% of cases. We did not perform longitudinal sampling and did not have autopsy-confirmed causes of death.
In this study, we did not identify a major contribution from coinfections to these deaths. Disseminated tuberculosis, sepsis syndrome, and rifampicin resistance were associated with mortality. An immune profile dominated by mediators of the innate immune system and chemotactic signaling was associated with both tuberculosis dissemination and mortality. These findings provide pathophysiologic insights into underlying causes of mortality and could be used to inform the development of novel treatment strategies and to develop methods to risk stratify patients to appropriately target novel interventions. Causal relationships cannot be established from this study.
The transition between latent and active tuberculosis (TB) occurs before symptom onset. Better understanding of the early events in subclinical disease will facilitate the development of diagnostics ...and interventions that improve TB control. This is particularly relevant in the context of HIV-1 coinfection where progression of TB is more likely. In a recent study using 18F-fluoro-2-deoxy-D-glucose positron emission/computed tomography (FDG-PET/CT) on 35 asymptomatic, HIV-1–infected adults, we identified 10 participants with radiographic evidence of subclinical disease, significantly more likely to progress than the 25 participants without. To gain insight into the biological events in early disease, we performed blood-based whole genome transcriptomic analysis on these participants and 15 active patients with TB. We found transcripts representing the classical complement pathway and Fcγ receptor 1 overabundant from subclinical stages of disease. Levels of circulating immune (antibody/antigen) complexes also increased in subclinical disease and were highly correlated with C1q transcript abundance. To validate our findings, we analyzed transcriptomic data from a publicly available dataset where samples were available in the 2 y before TB disease presentation. Transcripts representing the classical complement pathway and Fcγ receptor 1 were also differentially expressed in the 12 mo before disease presentation. Our results indicate that levels of antibody/antigen complexes increase early in disease, associated with increased gene expression of C1q and Fcγ receptors that bind them. Understanding the role this plays in disease progression may facilitate development of interventions that prevent this, leading to a more favorable outcome and may also be important to diagnostic development.
The pathogenesis of tuberculous meningitis Davis, Angharad Grace; Rohlwink, Ursula Karin; Proust, Alizé ...
Journal of leukocyte biology,
February 2019, Letnik:
105, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Tuberculosis (TB) remains a leading cause of death globally. Dissemination of TB to the brain results in the most severe form of extrapulmonary TB, tuberculous meningitis (TBM), which represents a ...medical emergency associated with high rates of mortality and disability. Via various mechanisms the Mycobacterium tuberculosis (M.tb) bacillus disseminates from the primary site of infection and overcomes protective barriers to enter the CNS. There it induces an inflammatory response involving both the peripheral and resident immune cells, which initiates a cascade of pathologic mechanisms that may either contain the disease or result in significant brain injury. Here we review the steps from primary infection to cerebral disease, factors that contribute to the virulence of the organism and the vulnerability of the host and discuss the immune response and the clinical manifestations arising. Priorities for future research directions are suggested.
Inhibition of the TOR signalling pathway by genetic or pharmacological intervention extends lifespan in invertebrates, including yeast, nematodes and fruitflies; however, whether inhibition of mTOR ...signalling can extend lifespan in a mammalian species was unknown. Here we report that rapamycin, an inhibitor of the mTOR pathway, extends median and maximal lifespan of both male and female mice when fed beginning at 600 days of age. On the basis of age at 90% mortality, rapamycin led to an increase of 14% for females and 9% for males. The effect was seen at three independent test sites in genetically heterogeneous mice, chosen to avoid genotype-specific effects on disease susceptibility. Disease patterns of rapamycin-treated mice did not differ from those of control mice. In a separate study, rapamycin fed to mice beginning at 270 days of age also increased survival in both males and females, based on an interim analysis conducted near the median survival point. Rapamycin may extend lifespan by postponing death from cancer, by retarding mechanisms of ageing, or both. To our knowledge, these are the first results to demonstrate a role for mTOR signalling in the regulation of mammalian lifespan, as well as pharmacological extension of lifespan in both genders. These findings have implications for further development of interventions targeting mTOR for the treatment and prevention of age-related diseases.
To assess the impact of local commissioners' policies for body mass index on access to knee replacement surgery in England. A Natural Experimental Study using interrupted time series and ...difference-in-differences analysis. We used National Joint Registry for England data linked to the 2015 Index of Multiple Deprivation for 481,555 patients who had primary knee replacement surgery in England between January 2009 and December 2019. Clinical Commissioning Group policies introduced before June 2018 to alter access to knee replacement for patients who were overweight or obese were considered the intervention. The main outcome measures were rate per 100,000 of primary knee replacement surgery and patient demographics (body mass index, Index of Multiple Deprivation, independently-funded surgery) over time. Rates of surgery had a sustained fall after the introduction of a policy (trend change of -0.98 operations per 100,000 population aged 40+, 95% confidence interval -1.22 to -0.74, P<0.001), whereas rates increased in localities with no policy introduction. At three years after introduction, there were 10.5 per 100,000 population fewer operations per quarter aged 40+ compared to the counterfactual, representing a fall of 14.1% from the rate expected had there been no change in trend. There was no dose response effect with policy severity. Rates of surgery fell in all patient groups, including non-obese patients following policy introduction. The proportion of independently-funded operations increased after policy introduction, as did the measure of socioeconomic deprivation of patients. Body mass index policy introduction was associated with decreases in the rates of knee replacement surgery across localities that introduced policies. This affected all patient groups, not just obese patients at whom the policies were targeted. Changes in patient demographics seen after policy introduction suggest these policies may increase health inequalities and further qualitative research is needed to understand their implementation and impact.
Strains of Mycobacterium tuberculosis vary in virulence. Strains that have caused outbreaks in the United States and United Kingdom have been shown to subvert the innate immune response as a ...potential immune evasion mechanism. There is, however, little information available as to whether these patterns of immune subversion are features of individual strains or characteristic of broad clonal lineages of M. tuberculosis.
Strains from two major modern lineages (lineage 2 East-Asian and lineage 4 Euro-American) circulating in the Western Cape in South Africa as well as a comparator modern lineage (lineage 3 CAS/Delhi) were identified. We assessed two virulence associated characteristics: mycobacterial growth (in liquid broth and monocyte derived macrophages) and early pro-inflammatory cytokine induction.
In liquid culture, Lineage 4 strains grew more rapidly and reached higher plateau levels than other strains (lineage 4 vs. lineage 2 p=0.0024; lineage 4 vs. lineage 3 p=0.0005). Lineage 3 strains were characterized by low and early plateau levels, while lineage 2 strains showed an intermediate growth phenotype. In monocyte-derived macrophages, lineage 2 strains grew faster than lineage 3 strains (p<0.01) with lineage 4 strains having an intermediate phenotype. Lineage 2 strains induced the lowest levels of pro-inflammatory TNF and IL-12p40 as compared to other lineages (lineage 2: median TNF 362 pg/ml, IL-12p40 91 pg/ml; lineage 3: median TNF 1818 pg/ml, IL-12p40 123 pg/ml; lineage 4: median TNF 1207 pg/ml, IL-12p40 205 pg/ml;). In contrast, lineage 4 strains induced high levels of IL-12p40 and intermediate level of TNF. Lineage 3 strains induced high levels of TNF and intermediate levels of IL-12p40.
Strains of M. tuberculosis from the three major modern strain lineages possess distinct patterns of growth and cytokine induction. Rapid growth and immune subversion may be key characteristics to the success of these strains in different human populations.
ABSTRACT
Resistance exercise training (RET) is widely used to increase muscle mass in athletes and also aged/cachectic populations. However, the time course and metabolic and molecular control of ...hypertrophy remain poorly defined. Using newly developed deuterium oxide (D2O)‐tracer techniques, we investigated the relationship between long‐term muscle protein synthesis (MPS) and hypertrophic responses to RET. A total of 10 men (23 ± 1 yr) undertook 6 wk of unilateral (1‐legged) RET 6 × 8 repetitions, 75% 1 repetition maximum (1‐RM) 3/wk, rendering 1 leg untrained (UT) and the contralateral, trained (T). After baseline bilateral vastus lateralis (VL) muscle biopsies, subjects consumed 150 ml D2O (70 atom percentage; thereafter 50 ml/wk) with regular body water monitoring in saliva via high‐temperature conversion elemental analyzer:isotope ratio mass spectrometer. Further bilateral VL muscle biopsies were taken at 3 and 6 wk to temporally quantify MPS via gas chromatography:pyrolysis:isotope ratio mass spectrometer. Expectedly, only the T leg exhibited marked increases in function i.e., 1‐RM/maximal voluntary contraction (60°) and VL thickness (peaking at 3 wk). Critically, whereas MPS remained unchanged in the UT leg (e.g., ∼1.35 ± 0.08%/d), the T leg exhibited increased MPS at 0‐3 wk (1.6 ± 0.01%/d), but not at 3‐6 wk (1.29 ± 0.11%/d); this was reflected by dampened acute mechanistic target of rapamycin complex 1 signaling responses to RET, beyond 3 wk. Therefore, hypertrophic remodeling is most active during the early stages of RET, reflecting longer‐term MPS. Moreover, D2O heralds promise for coupling MPS and muscle mass and providing insight into the control of hypertrophy and efficacy of anabolic interventions.—Brook, M. S., Wilkinson, D. J., Mitchell, W. K., Lund, J. N., Szewczyk, N. J., Greenhaff, P. L., Smith, K., Atherton, P. J. Skeletal muscle hypertrophy adaptations predominate in the early stages of resistance exercise training, matching deuterium oxide‐derived measures of muscle protein synthesis and mechanistic target of rapamycin complex 1 signaling. FASEB J. 29, 4485‐4496 (2015). www.fasebj.org
The drive to increase the output of animal product in some sectors of ruminant livestock production has led to greater use of feeds such as cereal grains and soyabean meal that are potentially ...human-edible. This trend has caused concern since, by so doing, ruminants compete not only with monogastric livestock but also with the human population for a limited global area of cultivatable land on which to produce grain crops. Reasons for using potentially human-edible feeds in ruminant diets include increased total daily energy intake, greater supply of essential amino acids and improved ruminal balance between fermentable energy and degradable protein. Soyabean meal, produced on land that has been in arable cultivation for many years can fulfil a useful role as a supplier of undegraded dietary protein in diets for high-yielding dairy cows. However, in the context of sustaining the production of high-quality foods from livestock to meet the demands of a growing human population, the use of potentially human-edible feed resources by livestock should be restricted to livestock with the highest daily nutrient requirements; that is, potentially human-edible feed inputs should be constrained to meeting requirements for energy and protein and to rectifying imbalances in nutrient supply from pastures and forage crops such as high concentrations of nitrogen (N). There is therefore a role for human-edible feeds in milk production because forage-only systems are associated with relatively low output per head and also low N use efficiency compared with systems with greater reliance on human-edible feeds. Profitability on farm is driven by control of input costs as well as product value and examples are given of low-cost bovine milk and meat production with little or no reliance on potentially human-edible feeds. In beef production, the forage-only systems currently under detailed real-time life-cycle analysis at the North Wyke Farm Platform, can sustain high levels of animal growth at low feed cost. The potential of all-forage diets should be demonstrated for a wide range of ruminant milk and meat production systems. The challenge for the future development of ruminant systems is to ensure that potentially human-edible feeds, or preferably human-inedible by-products if available locally, are used to complement pastures and forage crops strategically rather than replace them.
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