Lung infections with Mycobacterium abscessus, a species of multidrug resistant nontuberculous mycobacteria, are emerging as an important global threat to individuals with cystic fibrosis (CF) where they accelerate inflammatory lung damage leading to increased morbidity and mortality. Previously, M. abscessus was thought to be independently acquired by susceptible individuals from the environment. However, using whole genome analysis of a global collection of clinical isolates, we show that the majority of M. abscessus infections are acquired through transmission, potentially via fomites and aerosols, of recently emerged dominant circulating clones that have spread globally. We demonstrate that these clones are associated with worse clinical outcomes, show increased virulence in cell-based and mouse infection models, and thus represent an urgent international infection challenge.Nontuberculous mycobacteria (NTM; referring to mycobacterial species other than M. tuberculosis complex and M. leprae) are ubiquitous environmental organisms that can cause chronic pulmonary infections in susceptible individuals [1,2], particularly those with preexisting inflammatory lung diseases such as cystic fibrosis (CF) [3]. The major NTM infecting CF individuals around the world is Mycobacterium abscessus; a rapidly growing, intrinsically multidrug-resistant species, which can be impossible to treat despite prolonged combination antibiotic therapy [1,[3][4][5], leads to accelerated decline in lung function [6,7], and remains a contraindication to lung transplantation in many centers [3,8,9].Until recently, NTM infections were thought to be independently acquired by individuals through exposure to soil or water [10][11][12]. As expected, previous analyses from the 1990s and 2000s [13][14][15][16] showed that CF patients were infected with unique, genetically diverse strains of M. abscessus, presumably from environmental sources. We used whole genome sequencing at a single UK CF center and identified two clusters of patients (11 individuals in total) infected with identical or near-identical M. abscessus isolates, which social network analysis suggested were acquired within hospital via indirect transmission between patients Phylogenetic analysis of these sequences (using one isolate per patient), supplemented by published genomes from US, France, Brazil, Malaysia, China, and South Korea (Table S1), was performed and analysed in the context of the geographical provenance of isolates ( Figure 1; Figure S1). Within each subspecies, we found multiple examples of deep branches (indicating large genetic differences) between isolates from different individuals, consistent with independent acquisition of unrelated environmental bacteria. However, we also identified multiple clades of near-identical isolates from geographically diverse locations (Figure 1), suggesting widespread transmission of circulating clones within the global CF patient community.To investigate further the relatedness of isolates from different individuals, we a...

The chemokine receptors CCR5 and CXCR4 serve, in addition to CD4, as coreceptors for human immunodeficiency virus-1 (HIV-1), and infection with HIV-1 can cause dementia. In brain-derived cells, HIV-1 envelope glycoprotein gp120 initiates a signaling cascade that involves p38 mitogen-activated protein kinase and leads to neuronal cell death. Using mixed neuronal/glial cultures from rats and mice genetically deficient in one or both HIV coreceptors, we show here that CCR5, CXCR4 or both can mediate HIV/ gp120 neurotoxicity depending on the viral strain. Paradoxically, we also found evidence for a CCR5-mediated neuroprotective pathway. We identify protein kinase Akt/PKB as an essential component of this pathway, which can be triggered by the CCR5 agonists macrophage inflammatory protein-1b and regulated-and-normal-T-cell-expressed-and-secreted. Moreover, these CCR5 ligands prevent neuronal cell death induced by stromal cell-derived factor-1, a CXCR4 agonist. Both neurons and glia coexpress CXCR4 and CCR5. Ca 2 þ imaging experiments demonstrate that engagement of CCR5 prevents CXCR4-triggered increases in intracellular free Ca 2 þ . This finding suggests that CCR5 ligands can protect neurons at least, in part, by modulating CXCR4-mediated toxicity through heterologous desensitization.

Alzheimer's disease (AD) is a progressively debilitating brain disorder pathologically defined by extracellular amyloid plaques, intraneuronal neurofibrillary tangles, and synaptic disintegrity. AD has not been widely considered a disease of white matter, but more recent evidence suggests the existence of abnormalities in myelination patterns and myelin attrition in AD-afflicted human brains. Herein, we demonstrate that triple-transgenic AD (3xTg-AD) mice, which harbor the human amyloid precursor protein Swedish mutant transgene, presenilin knock-in mutation, and tau P301L mutant transgene, exhibit significant region-specific alterations in myelination patterns and in oligodendrocyte marker expression profiles at time points preceding the appearance of amyloid and tau pathology. These immunohistochemical signatures are coincident with age-related alterations in axonal and myelin sheath ultrastructure as visualized by comparative electron microscopic examination of 3xTg-AD and non-transgenic mouse brain tissue. Overall, these findings indicate 3xTg-AD mice represent a viable model in which to examine mechanisms underlying AD-related myelination and neural transmission defects that occur early during pre-symptomatic stages of the disease process.

The detection of myelin disruptions in Alzheimer's disease (AD)-affected brain raises the possibility that oligodendrocytes undergo pathophysiological assault over the protracted course of this neurodegenerative disease. Oligodendrocyte compromise arising from direct toxic effects imparted by pathological amyloid-␤ peptides and/or through signals derived from degenerating neurons could play an important role in the disease process. We previously demonstrated that 3؋Tg-AD mice, which harbor the human amyloid precursor protein Swedish mutant transgene, presenilin knock-in mutation, and tau P301L mutant transgene, exhibit significant alterations in overall myelination patterns and oligodendrocyte status at time points preceding the appearance of amyloid and tau pathology. Herein, we demonstrate that A␤ 1-42 leads to increased caspase-3 expression and apoptotic cell death of both nondifferentiated and differentiated mouse oligodendrocyte precursor (mOP) cells in vitro. Through use of a recombinant adeno-associated virus serotype-2 (rAAV2) vector expressing an A␤ 1-42 -specific intracellular antibody (intrabody), oligodendrocyte and myelin marker expression, as well as myelin integrity, were restored in the vector-infused brain regions of 3؋Tg-AD mice. Overall, this work provides further insights into the impact of A␤ 1-42 -mediated toxicity on the temporal and spatial progression of subtle myelin disruption during the early presymptomatic stages of AD and may help to validate new therapeutic options designed to avert these early impairments.

HIV-1 envelope protein gp120 has been implicated in neurotoxin production by monocytic cells, namely macrophages and microglia, and the pathogenesis of HIV-1 associated neurocognitive disorders (HAND). We previously showed in cerebrocortical cell cultures from rodents containing microglia, astrocytes and neurons, that overall inhibition of p38 MAPK signaling abrogated the neurotoxic effect of HIV-1 gp120. However, the time course of p38 MAPK activation and the contribution of this kinase in the various cell types remained unknown. In this study, we found that for HIV gp120-induced neurotoxicity to occur, active p38 MAPK is required in monocytic lineage cells, namely macrophages and microglia, and neuronal cells. In cerebrocortical cell cultures HIV-1 gp120 stimulated a time-dependent overall increase of active p38 MAPK and the activated kinase was primarily detected in microglia and neurons. Interestingly, both increased activation of p38 MAPK and neuronal death in response to gp120 were prevented by prior depletion of microglia, or in the presence of CCR5 ligand CCL4 or of p38 MAPK inhibitors. In human monocytic THP-1 cells and primary monocyte-derived macrophages (MDM), HIV gp120 stimulated production of neurotoxins was abrogated by prior introduction into the cells of a dominant-negative p38 MAPK mutant or p38 MAPK siRNA. In addition, the neurotoxic effects of cell-free supernatants from gp120-stimulated monocytic THP-1 cells were prevented in microglia-depleted cerebrocortical cells pretreated with a pharmacological inhibitor of p38 MAPK. Thus, p38 MAPK signaling was critical upon exposure to HIV gp120 for both the neurotoxic phenotype of monocytic cells and subsequent toxin-initiated neuronal apoptosis.

The innate immune system has been implicated in several neurodegenerative diseases, including human immunodeficiency virus (HIV)-1 associated dementia. Here we show that genetic ablation of CCR5 prevents microglial activation and neuronal damage in a transgenic model of HIV-associated brain injury induced by a CXCR4-utilizing viral envelope gp120. The CCR5 knockout (KO) also rescues spatial learning and memory in gp120-transgenic (tg) mice. However, the CCR5KO does not abrogate astrocytosis, indicating it can occur independently from neuronal injury and behavioral impairment. To further characterize the neuroprotective effect of CCR5-deficiency we performed a genome –wide gene expression analysis of brains from HIVgp120tg mice expressing or lacking CCR5 and non-transgenic controls. Comparison with a human brain microarray study reveals that brains of HIVgp120tg mice and HIV patients with neurocognitive impairment share numerous differentially regulated genes. Furthermore, brains of CCR5 wild-type (WT) and CCR5KO gp120tg mice express markers of an innate immune response. One of the most significantly up-regulated factors is the acute phase protein lipocalin-2 (LCN2). Using cerebrocortical cell cultures, we find that LCN2 is neurotoxic in a CCR5-dependent fashion while inhibition of CCR5 alone is not sufficient to abrogate neurotoxicity of a CXCR4-utilizing gp120. However, the combination of pharmacological CCR5 blockade and LCN2 protects neurons from toxicity of a CXCR4-utilizing gp120 thus recapitulating the finding in CCR5-deficient gp120tg mouse brain. Altogether, our study provides evidence for an indirect pathological role of CCR5 and a novel protective effect of LCN2 in combination with inhibition of CCR5 in HIV-associated brain injury.

Mycobacteria are a large family of over 100 species, most of which do not cause diseases in humans. The majority of the mycobacterial species are referred to as nontuberculous mycobacteria (NTM), meaning they are not the causative agent of tuberculous (TB) or leprosy, i.e., Mycobacterium tuberculous complex and Mycobacterium leprae, respectively. The latter group is undoubtedly the most infamous, with TB infecting an estimated 10 million people and causing over 1.2 million deaths in 2017 alone TB and leprosy also differ from NTM in that they are only transmitted from person to person and have no environmental reservoir, whereas NTM infections are commonly acquired from the environment. It took until the 1950′s for NTM to be recognised as a potential lung pathogen in people with underlying pulmonary disease and another three decades for NTM to be widely regarded by the medical community when Mycobacterium avium complex was identified as the most common group of opportunistic pathogens in AIDS patients. This review focuses on an emerging NTM called Mycobacterium abscessus (M. abs). M. abs is a rapidly growing NTM that is responsible for opportunistic pulmonary infections in patients with structural lung disorders such as cystic fibrosis and bronchiectasis, as well as a wide range of skin and soft tissue infections in humans. In this review, we discuss how we came to understand the pathogen, how it is currently treated and examine drug resistance mechanisms and novel treatments currently in development. We highlight the urgent need for new and effective treatments for M. abs infection as well as improved in vivo methods of efficacy testing.

The change in resistance of Burkholderia cepacia to ceftazidime and to ciprofloxacin during the exponential phase and up to the onset of stationary phase was assessed along the growth curve in batch culture. B. cepacia was grown in planktonic culture and in a biofilm on a membrane support. Resistance increased progressively during the exponential phase, being increased by ten-fold about every four generations. Bacteria grown in a biofilm were about 15 times more resistant than equivalent planktonic-grown bacteria. The growth rate was not the key factor for the development of resistance. The growth phase and the mode of growth have a fundamental impact on the susceptibility of B. cepacia towards antimicrobial agents. Bacteria growing at the same rate may differ greatly in their resistance to antimicrobial agents.