Search

Infection with herpes simplex virus type 1 (HSV-1) in the brains of APOE4 carriers increases the risk of Alzheimer's disease (AD). We previously found that latent HSV-1 in a three-dimensional in vitro model of APOE4-heterozygous human brain tissue was reactivated in response to neuroinflammation caused by exposure to other pathogens. Because traumatic brain injury also causes neuroinflammation, we surmised that brain injury might similarly reactivate latent HSV-1. Here, we examined the effects of one or more controlled blows to our human brain model in the absence or presence of latent HSV-1 infection. After repeated, mild controlled blows, latently infected tissues showed reactivation of HSV-1; the production and accumulation of β amyloid and phosphorylated tau (which promotes synaptic dysfunction and neurodegeneration); and activated gliosis, which is associated with destructive neuroinflammation. These effects are collectively associated with AD, dementia, and chronic traumatic encephalopathy (CTE) and were increased with additional injury but were absent in mock-infected tissue. Blocking the cytokine IL-1β prevented the induction of amyloid and gliosis in latently infected monolayer cultures after scratch wounding. We thus propose that after repeated mechanical injuries to the brain, such as from direct blows to the head or jarring motions of the head, the resulting reactivation of HSV-1 in the brain may contribute to the development of AD and related diseases in some individuals. Editor's summary: Infection with herpes simplex virus type 1 (HSV-1) is common, lifelong, and often in a latent state with periodic reactivation. It is a risk factor for neurodegenerative disease and dementia in some individuals, as are repeated head injuries like concussions. Cairns et al. found that latent HSV-1 was reactivated by repeated mechanical injury to mimic concussions in a three-dimensional human brain tissue model. This mechanism triggered the aggregation of β amyloid and other pathological features associated with neurodegenerative diseases in a manner dependent on the inflammatory cytokine IL-1β. The findings directly link two risk factors in a mechanism that may contribute to dementia-related disease. —Leslie K. Ferrarelli [ABSTRACT FROM AUTHOR]

It is increasingly common for apex predators to face a multitude of complex conservation issues. In Australia, dingoes are the mainland apex predator and play an important role in ecological functioning. Currently, however, they are threatened by hybridization with modern domestic dogs in the wild. As a consequence, we explore how increasing our understanding of the evolutionary history of dingoes can inform management and conservation decisions. Previous research on whole mitochondrial genome and nuclear data from five geographical populations showed evidence of two distinct lineages of dingo. Here, we present data from a broader survey of dingoes around Australia using both mitochondrial and Y chromosome markers and investigate the timing of demographic expansions. Biogeographic data corroborate the presence of at least two geographically subdivided genetic populations, southeastern and northwestern. Demographic modeling suggests that dingoes have undergone population expansion in the last 5,000 years. It is not clear whether this stems from expansion into vacant niches after the extinction of thylacines on the mainland or indicates the arrival date of dingoes. Male dispersal is much more common than female, evidenced by more diffuse Y haplogroup distributions. There is also evidence of likely historical male biased introgression from domestic dogs into dingoes, predominately within southeastern Australia. These findings have critical practical implications for the management and conservation of dingoes in Australia; particularly a focus must be placed upon the threatened southeastern dingo population.

Paneth cells at the bottom of small intestinal crypts secrete antimicrobial peptides, enzymes, and growth factors and contribute to pathogen clearance and maintenance of the stem cell niche. Loss of Paneth cells and their dysfunction occur commonly in various pathologies, but the mechanism underlying the control of Paneth cell function remains largely unknown. Here, we identified microRNA-195 (miR-195) as a repressor of Paneth cell development and activity by altering SOX9 translation via interaction with RNA-binding protein HuR. Tissue-specific transgenic expression of miR-195 (miR195-Tg) in the intestinal epithelium decreased the levels of mucosal SOX9 and reduced the numbers of lysozyme-positive (Paneth) cells in mice. Ectopically expressed SOX9 in the intestinal organoids derived from miR-195-Tg mice restored Paneth cell development ex vivo. miR-195 did not bind to Sox9 mRNA but it directly interacted with HuR and prevented HuR binding to Sox9 mRNA, thus inhibiting SOX9 translation. Intestinal mucosa from mice that harbored both Sox9 transgene and ablation of the HuR locus exhibited lower levels of SOX9 protein and Paneth cell numbers than those observed in miR-195-Tg mice. Inhibition of miR-195 activity by its specific antagomir improved Paneth cell function in HuR-deficient intestinal organoids. These results indicate that interaction of miR-195 with HuR regulates Paneth cell function by altering SOX9 translation in the small intestinal epithelium. NEW & NOTEWORTHY: Our results indicate that intestinal epithelial tissue-specific transgenic miR-195 expression decreases the levels of SOX9 expression, along with reduced numbers of Paneth cells. Ectopically expressed SOX9 in the intestinal organoids derived from miR-195-Tg mice restores Paneth cell development ex vivo. miR-195 inhibits SOX9 translation by preventing binding of HuR to Sox9 mRNA. These findings suggest that interaction between miR-195 and HuR controls Paneth cell function via SOX9 in the intestinal epithelium. [ABSTRACT FROM AUTHOR]

Background: PTEN hamartoma tumour syndrome (PHTS) comprises a group of genetic disorders with varied clinical presentations, including macrocephaly, developmental delay, and increased cancer susceptibility. Recent reports have highlighted the occurrence of tonsil-related issues in PHTS. Methods: Clinical data focusing on tonsil-related pathology and tonsillectomy details (indications, histology and post-operative complications) were collected from 53 patients with PHTS. Results: Tonsil issues affected 58 per cent of the cohort, with 43 per cent requiring tonsillectomy. Primary indications for tonsillectomy included obstructive sleep apnoea (43 per cent), recurrent tonsillitis (17 per cent) and other causes (17 per cent). Tonsil-related problems were observed both before (45 per cent) and after (55 per cent) PHTS. Tonsillectomy with adenoidectomy was the predominant surgical intervention performed (87 per cent), spanning a broad age range (1–27 years old). Discussion: Our findings highlight the complex nature of PHTS and its association with tonsil-related pathology, demonstrating its relevance for ENT surgeons. Early recognition and intervention are pivotal for managing sleep apnoea and the associated health problems. [ABSTRACT FROM AUTHOR]

The Special Issue on Herpes Virus Fusion and Entry in the journal Viruses explores the complex mechanisms by which herpesviruses enter host cells using viral glycoproteins. The studies focus on the role of key glycoproteins, such as gB, gH/gL, and gD, in mediating viral entry and spread. The research sheds light on the intricate processes involved in herpesvirus infection, offering insights that could inform the development of antiviral therapies and vaccines. The authors of the studies presented in this issue provide valuable contributions to understanding the fusion machinery of herpesviruses and potential targets for therapeutic interventions. [Extracted from the article]

Dingoes come from an ancient canid lineage that originated in East Asia around 8,000 to 11,000 years BP. As Australia's largest terrestrial predator, dingoes play an important ecological role. A small, protected population exists on a world heritage listed offshore island, K'gari (formerly Fraser Island). Concern regarding the persistence of dingoes on K'gari has risen due to their low genetic diversity and elevated inbreeding levels. However, whole-genome sequence data is lacking from this population. Here, we include five new whole-genome sequences of K'gari dingoes. We analyze a total of 18 whole-genome sequences of dingoes sampled from mainland Australia and K'gari to assess the genomic consequences of their demographic histories. Long (>1 Mb) runs of homozygosity (ROHs)—indicators of inbreeding—are elevated in all sampled dingoes. However, K'gari dingoes showed significantly higher levels of very long ROH (>5 Mb), providing genomic evidence for small population size, isolation, inbreeding, and a strong founder effect. Our results suggest that, despite current levels of inbreeding, the K'gari population is purging strongly deleterious mutations, which, in the absence of further reductions in population size, may facilitate the persistence of small populations despite low genetic diversity and isolation. However, there may be little to no purging of mildly deleterious alleles, which may have important long-term consequences, and should be considered by conservation and management programs. [ABSTRACT FROM AUTHOR]