Disease Models & Mechanisms最新文献

Huntington's disease (HD) is traditionally viewed as an age-related disorder. Emerging evidence suggests that mutant huntingtin (mHTT) disrupts early neurodevelopment, although the contribution of developmental alterations to the late disease onset remains to be clarified. Leveraging human pluripotent stem cell-derived brain organoids, we and others are exploring how mHTT affects the developing human brain. These models reveal impaired neural progenitor organization and function, accompanied by a mitochondrial stress response, indicating reduced capacity to manage cellular stress. Enhancing mitochondrial health and promoting neural cell resilience may thus represent potential strategies for improving the brain's compensatory mechanisms, thereby prolonging a healthy state. These insights highlight a potential window of opportunity for therapeutic interventions. Targeting mitochondrial fitness and neurodevelopmental pathways at early stages - long before clinical symptoms emerge - could help prevent or delay disease onset and progression in affected individuals.

Tremor is a common movement disorder associated with several neurodegenerative diseases, yet its mechanisms are not well understood. Using a machine-learning method, Feature Learning-based Leg segmentation and Tracking (FLLIT), we previously characterised gait and tremor signatures in a Drosophila model for spinocerebellar ataxia 3 (SCA3) and found them to be analogous to those in human SCA3. Here, we carried out a functional screen for neuronal populations that underlie tremor and found that dysfunction of a specific population of neurons in the ventral nerve cord (VNC) is necessary and sufficient for tremor. Adult-onset expression of mutant ATXN3 in, or genetic hypo-activation of, these neurons led to tremor, indicating their important role in adult motor control. RNA-sequencing and functional experiments showed that dysfunction of GABAergic neurons, and not that of other neurotransmitter populations tested, causes tremor. Finally, we identified a small subset of ∼30 predominantly GABAergic neurons within the adult VNC that are essential for smooth walking. This study demonstrates that tremor in SCA3 flies arises from GABAergic dysfunction, and that FLLIT can be used to dissect motor control mechanisms.

Cryptococcus deneoformans (Cd) and C. neoformans (Cn) differ in geographic prevalence and dermatotropism, with Cd strains more commonly isolated from temperate regions and skin infections. Rising global temperatures prompt concerns regarding selection for environmental fungal species with increased thermotolerance, as high mammalian temperatures provide protection against many fungal species. Cd and Cn strains exhibit variations in thermal susceptibility, with Cd strains being more susceptible to higher temperatures. Here, we identified differences in capsular polysaccharide release, adhesion and biofilm formation between strains both in vivo and in vitro. Histological results suggested that the dermatotropic predilection associated with Cd relates to biofilm formation, possibly facilitating latency and extending fungal survival through protection from high temperatures. We demonstrated that Cn strains were more tolerant to mammalian and febrile temperatures than Cd strains. Similarly, Cd strains showed reduced expression of heat-shock protein 60 and 70, after prolonged exposure to high temperature. Our findings suggest that fungal adhesion, biofilm formation, inflammation and thermotolerance contribute to tissue tropism and disease manifestation by Cn and Cd, supporting the recently assigned species distinction to each of these serotypes.

Antimicrobial resistance represents one of the most serious threats to both public health and economic sustainability. One of the promising approaches to address this problem is phage therapy - treatment of pathogenic bacterial infections using bacteriophages. Bacteriophages have a narrow host spectrum of activity, minimal side effects and self-replication at the infection site, which positions them as promising candidates to complement or replace conventional antibiotics. Moreover, they can be easily genetically modified to enhance their effectiveness and safety. In this At a Glance article, we highlight the timely relevance of engineered phages as an innovative solution in a rapidly evolving healthcare landscape. First, we introduce bacteriophages' life cycle, ecology and therapeutic history, emphasizing their role in One Health strategies. Then, we describe advanced engineering techniques that can be used to expand bacteriophages' functionalities. Finally, we discuss innovative applications of engineered bacteriophages in biotechnological applications and as a potential countermeasure for antimicrobial resistance, including serving as a shuttle for delivering genes and drugs to the targeted bacterial and eukaryotic cells, targeting intracellular bacteria, contributing to vaccine development, facilitating advancements in tissue engineering and improving bacteriophages' antibacterial properties.

Bats are a natural reservoir for a wide variety of notorious viruses that are deadly to humans and other mammals but cause no or minimal clinical damage in bats. The co-evolution of bats and viruses for more than sixty million years has established unique and balanced immune defenses within bats against a number of viruses. With the COVID-19 pandemic, bats have gained greater attention as a likely reservoir of the SARS-CoV-2 ancestor virus. The coupling of omics technology and bat research opens an exciting new field to understand and translate discoveries from bats to humans, in the context of infectious disease and beyond. Here, we focus on the mechanism of immunity balance in bats, the application of omics and how this might lead to improvement of human health.

Since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) initiated a global pandemic resulting in an estimated 775 million infections with over 7 million deaths, it has become evident that COVID-19 is not solely a pulmonary disease. Emerging evidence has shown that, in a subset of patients, certain symptoms - including chest pain, stroke, anosmia, dysgeusia, diarrhea and abdominal pain - all indicate a role of vascular, neurological and gastrointestinal (GI) pathology in the disease process. Many of these disease processes persist long after the acute disease has been resolved, resulting in 'long COVID' or post-acute sequelae of COVID-19 (PASC). The molecular mechanisms underlying the acute and systemic conditions associated with COVID-19 remain incompletely defined. Appropriate animal models provide a method of understanding underlying disease mechanisms at the system level through the study of disease progression, tissue pathology, immune system response to the pathogen and behavioral responses. However, very few studies have addressed PASC and whether existing models hold promise for studying this challenging problem. Here, we review the current literature on cardiovascular, neurological and GI pathobiology caused by COVID-19 in patients, along with established animal models of the acute disease manifestations and their prospects for use in PASC studies. Our aim is to provide guidance for the selection of appropriate models in order to recapitulate certain aspects of the disease to enhance the translatability of mechanistic studies.

Tuberculosis (TB) is characterized by the formation of heterogeneous, immune-rich granulomas in the lungs. Host and pathogen factors contribute to this heterogeneity, but the molecular and cellular drivers of granuloma diversity remain inadequately understood owing to limitations in experimental techniques. In this study, we developed an approach that combines passive CLARITY (PACT)-based clearing with light-sheet fluorescence microscopy to visualize lesion architecture and lung involvement in Mycobacterium tuberculosis-infected C3HeB/FeJ mice. Three-dimensional rendering of post-mortem lungs revealed critical architectural features in lesion development that traditional thin-section imaging could not detect. Wild-type M. tuberculosis infection resulted in organized granulomas, with median sizes increasing to 3.74×108 µm3 and occupying ∼10% of the total lung volume by day 70 post-infection. In contrast, infection with the avirulent ESX-1 deletion mutant strain resulted in diffuse and sparsely organized CD11b recruitment (median size of 8.22×107 µm3), primarily located in the lung periphery and minimally involving the airways (0.23% of the total lung space). Additionally, we present a method for volumetric correlative light and electron microscopy, enabling tracking of individual immune cell populations within granulomas.

The antiviral enzyme cholesterol 25-hydroxylase (CH25H) and its metabolite 25-hydroxycholesterol (25HC), which modulates cholesterol metabolism during infection, have been associated with vascular pathology. Viral infections have been linked to intracerebral haemorrhage (ICH) risk, but the molecular mechanisms leading to ICH via antiviral responses remain unknown. We hypothesised that the CH25H/25HC pathway impacts neuroendothelial integrity in the context of infection-associated ICH. Using a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein-induced zebrafish ICH model and foetal human SARS-CoV-2-associated cortical tissue containing microbleeds, we identified upregulation of CH25H in infection-associated cerebral haemorrhage. Using zebrafish models and human brain endothelial cells, we asked whether 25HC promotes neurovascular dysfunction by modulating cholesterol metabolism. We found that 25HC and pharmacological inhibition of cholesterol synthesis had an additive effect to exacerbate brain bleeding in zebrafish and in vitro neuroendothelial dysfunction. 25HC-induced dysfunction was also rescued by cholesterol supplementation in vitro. These results demonstrate that 25HC can dysregulate brain endothelial function by remodelling cholesterol metabolism. We propose that CH25H/25HC plays an important role in the pathophysiology of brain vessel dysfunction associated with infection and cholesterol dysregulation in the context of ICH.

Lung disease due to non-tuberculous mycobacteria (NTM) is rising in incidence. Although both two-dimensional cell culture and animal models exist for NTM infections, a major knowledge gap is the early responses of human alveolar and innate immune cells to NTM within the human alveolar microenvironment. Here, we describe the development of a humanized, three-dimensional, alveolus lung-on-a-chip (ALoC) model of Mycobacterium fortuitum lung infection that incorporates only primary human cells, such as pulmonary vascular endothelial cells, in a vascular channel, and type I and II alveolar cells and monocyte-derived macrophages in an alveolar channel along an air-liquid interface. M. fortuitum introduced into the alveolar channel primarily infected macrophages, with rare bacteria inside alveolar cells. Bulk RNA sequencing of infected chips revealed marked upregulation of transcripts for cytokines, chemokines and secreted protease inhibitors (SERPINs). Our results demonstrate how a humanized ALoC system can identify critical early immune and epithelial responses to M. fortuitum infection. We envision potential application of the ALoC to other NTM and in studies of new antibiotics.