The accelerated aging skin in rhino-like SHJHhr mice.

SHJHhr mice line is rhino-like mice with a nonsense Hairless (Hr) mutant, which shows the characteristic of shedding hair and wrinkled skin with increasing age. Through histological analysis and aging indexes detection, SHJHhr mice show an increased thickness skin with degraded hair follicle and dermal cysts and disorganized collagen fibres, as well as decreased level of Hyp. Meanwhile, the aging markers p16 and p21 are significantly higher in SHJHhr mouse skin than ICR mouse skin at same age. Moreover, the data of MDA and SOD show a higher oxidative stress in SHJHhr mouse skin, and the levels of Nrf2 and its targets are significantly downregulated, which suggests SHJHhr mice have a faster aging skin and its reason maybe poor antioxidative protection. Overall, this study shows SHJHhr mice with an accelerated aging skin, which suggests the role of Hr gene in skin aging.

Therapeutic reversal of Huntington's disease by in vivo self-assembled siRNAs.

Huntington's disease is an autosomal-dominant neurodegenerative disease caused by CAG expansion in exon 1 of the huntingtin (HTT) gene. Since mutant huntingtin (mHTT) protein is the root cause of Huntington's disease, oligonucleotide-based therapeutic approaches using small interfering RNAs (siRNAs) and antisense oligonucleotides designed to specifically silence mHTT may be novel therapeutic strategies for Huntington's disease. Unfortunately, the lack of an effective in vivo delivery system remains a major obstacle to realizing the full potential of oligonucleotide therapeutics, especially regarding the delivery of oligonucleotides to the cortex and striatum, the most severely affected brain regions in Huntington's disease. In this study, we present a synthetic biology strategy that integrates the naturally existing exosome-circulating system with artificial genetic circuits for self-assembly and delivery of mHTT-silencing siRNA to the cortex and striatum. We designed a cytomegalovirus promoter-directed genetic circuit encoding both a neuron-targeting rabies virus glycoprotein tag and an mHTT siRNA. After being taken up by mouse livers after intravenous injection, this circuit was able to reprogramme hepatocytes to transcribe and self-assemble mHTT siRNA into rabies virus glycoprotein-tagged exosomes. The mHTT siRNA was further delivered through the exosome-circulating system and guided by a rabies virus glycoprotein tag to the cortex and striatum. Consequently, in three mouse models of Huntington's disease treated with this circuit, the levels of mHTT protein and toxic aggregates were successfully reduced in the cortex and striatum, therefore ameliorating behavioural deficits and striatal and cortical neuropathologies. Overall, our findings establish a convenient, effective and safe strategy for self-assembly of siRNAs in vivo that may provide a significant therapeutic benefit for Huntington's disease.

Cortical microinfarcts potentiate recurrent ischemic injury through NLRP3-dependent trained immunity.

Microinfarcts are common among the elderly and patients with microinfarcts are more vulnerable to another stroke. However, the impact of microinfarcts on recurrent stroke has yet to be fully understood. The purpose of this study was to explore the negative effects of microinfarcts on recurrent stroke. To achieve this, two-photon laser was used to induce microinfarcts, while photothrombotic stroke was induced on the opposite side. The results showed that microinfarcts led to trained immunity in microglia, which worsened the pro-inflammatory response and ischemic injury in the secondary photothrombotic stroke. Additionally, the study clarified the role of NLRP3 in microglial nuclei, indicating that it interacts with the MLL1 complex through NACHT domain and increases H3K4 methylation, which suggests that NLRP3 is critical in the formation of innate immune memory caused by microinfarcts. Furthermore, the knockout of NLRP3 in microglia alleviated the trained immunity and reduced the harmful effects of microinfarcts on recurrent stroke. This study emphasizes the detrimental effect of trained immunity on recurrent stroke and highlights the critical role of NLRP3 in mediating the formation of this memory, which may offer a potential therapeutic target for mitigating recurrent strokes.

Comprehensive Assessment of Ischemic Stroke in Nonhuman Primates: Neuroimaging, Behavioral, and Serum Proteomic Analysis.

Ischemic strokes, prevalence and impactful, underscore the necessity of advanced research models closely resembling human physiology. Our study utilizes nonhuman primates (NHPs) to provide a detailed exploration of ischemic stroke, integrating neuroimaging data, behavioral outcomes, and serum proteomics to elucidate the complex interplay of factors involved in stroke pathophysiology. We observed a consistent pattern in infarct volume, peaking at 1-month postmiddle cerebral artery occlusion (MCAO) and then stabilized. This pattern was strongly correlated to notable changes in motor function and working memory performance. Using diffusion tensor imaging (DTI), we detected significant alterations in fractional anisotropy (FA) and mean diffusivity (MD) values, signaling microstructural changes in the brain. These alterations closely correlated with the neurological and cognitive deficits that we observed, highlighting the sensitivity of DTI metrics in stroke assessment. Behaviorally, the monkeys exhibited a reliance on their unaffected limb for compensatory movements, a common response to stroke impairment. This adaptation, along with consistent DTI findings, suggests a significant impact of stroke on motor function and spatial perception. Proteomic analysis through MS/MS functional enrichment identified two distinct groups of proteins with significant changes post-MCAO. Notably, MMP9, THBS1, MB, PFN1, and YWHAZ were identified as potential biomarkers and therapeutic targets for ischemic stroke. Our results underscore the complex nature of stroke and advocate for an integrated approach, combining neuroimaging, behavioral studies, and proteomics, for advancing our understanding and treatment of this condition.

Phosphorylation of AQP4 by LRRK2 R1441G impairs glymphatic clearance of IFNγ and aggravates dopaminergic neurodegeneration.

Aquaporin-4 (AQP4) is essential for normal functioning of the brain's glymphatic system. Impaired glymphatic function is associated with neuroinflammation. Recent clinical evidence suggests the involvement of glymphatic dysfunction in LRRK2-associated Parkinson's disease (PD); however, the precise mechanism remains unclear. The pro-inflammatory cytokine interferon (IFN) γ interacts with LRRK2 to induce neuroinflammation. Therefore, we examined the AQP4-dependent glymphatic system's role in IFNγ-mediated neuroinflammation in LRRK2-associated PD. We found that LRRK2 interacts with and phosphorylates AQP4 in vitro and in vivo. AQP4 phosphorylation by LRRK2 R1441G induced AQP4 depolarization and disrupted glymphatic IFNγ clearance. Exogeneous IFNγ significantly increased astrocyte expression of IFNγ receptor, amplified AQP4 depolarization, and exacerbated neuroinflammation in R1441G transgenic mice. Conversely, inhibiting LRRK2 restored AQP4 polarity, improved glymphatic function, and reduced IFNγ-mediated neuroinflammation and dopaminergic neurodegeneration. Our findings establish a link between LRRK2-mediated AQP4 phosphorylation and IFNγ-mediated neuroinflammation in LRRK2-associated PD, guiding the development of LRRK2 targeting therapy.

Ergothioneine Protects Against UV-Induced Oxidative Stress Through the PI3K/AKT/Nrf2 Signaling Pathway.

Background: Ergothioneine (EGT) is an antioxidant, which could be detected in human tissues, and human skin cells could utilize EGT and play an anti-oxidative role in keratinocytes. And in this study we are going to elucidate whether EGT could protect the skin from photoaging by Ultraviolet (UV) exposure in mice and its molecule pathway. Methods: Histological analysis was performed for evaluating the skin structure change. Malondialdehyde (MDA) and superoxide dismutase (SOD) levels were measured with biological assay for evaluating oxidative and antioxidative ability of skin exposed to UV light. And the level of marker molecules in mouse skin were detected by hydroxyproline (Hyp) assay, immunohistochemical analysis, Western blot, and quantitative real-time PCR (qRT-PCR). The markers of skin aging and cell death were tested by cell culture and treatment, Western blot and qRT-PCR. Results: EGT decreased the levels of inflammatory factors induced by UV exposure in mouse skin. MDA and SOD activity detection showed that EGT decreased MDA levels, increased SOD activity, and upregulated PI3K/Akt/Nrf2 signals in mouse skin exposed to UV, which further activated Nrf2 in the nucleus and enhanced the expression of Nrf2 target genes. In the cell model, we revealed that EGT could inhibit the increase in senescence-associated ß-galactosidase-positive cells and p16 and γ-H2A.X positive cells induced by etoposide and activate PI3K/Akt/Nrf2 signaling. Moreover, a PI3K inhibitor blocked EGT protection against etoposide-induced cell death. Conclusion: The study showed EGT may play an important protective role against cell damage or death through the PI3K/Akt/Nrf2 signaling pathway in skin.

Overexpression of Slit2 improves function of the paravascular pathway in the aging mouse brain.

Aging is associated with impairment of the paravascular pathway caused by the activation of astrocytes and depolarization of protein aquaporin­4 (AQP4) water channels, resulting in the accumulation of protein waste, including amyloid ß (Aß), in the brain parenchyma. The secreted glycoprotein slit guidance ligand 2 (Slit2) is important in regulating the function of the central nervous system and inflammatory response process. In the present study, 15­month­old Slit2 overexpression transgenic mice (Slit2­Tg mice) and two­photon fluorescence microscopy were used to evaluate the dynamic clearance of the paravascular pathway and the integrity of the blood­brain barrier (BBB). The reactivity of astrocytes, polarity of AQP4 and deposition of Aß in the brain parenchyma were analyzed by immunofluorescence. A Morris water maze test was used to examine the effect of Slit2 on spatial memory cognition in aging mice. It was found that the overexpression of Slit2 improved the clearance of the paravascular pathway by inhibiting astrocyte activation and maintaining AQP4 polarity on the astrocytic endfeet in Slit2­Tg mice. In addition, Slit2 restored the disruption of the BBB caused by aging. The accumulation of Aß was significantly reduced in the brain of Slit2­Tg mice. Furthermore, the water maze experiment showed that Slit2 improved spatial memory cognition in the aging mice. These results indicated that Slit2 may have the potential to be used in the prevention and treatment of neurodegenerative diseases in the elderly.

Targeted disruption of adenosine kinase in myeloid monocyte cells increases osteoclastogenesis and bone resorption in mice.

Adenosine kinase (ADK) serves an important role in intracellular adenosine clearance via phosphorylating adenosine to AMP. The role of adenosine and its receptors in the maintenance of bone homeostasis is well studied, particularly in osteoclastogenesis and bone resorption; however, the function of ADK in bone metabolism is still unclear. In the present study, utilizing the cre/floxp recombination system, mice with conditional loss of ADK function in myeloid monocyte cells were used to assess the effect of ADK deficiency on bone metabolism. Mice were evaluated by means of gross observation and bone histomorphometric analysis. Ex vivo osteoclast differentiation and bone resorption were also examined using genetic deletion and pharmacologic inhibition of ADK in osteoclasts. Compared with control mice, the results of the present study demonstrate that adult mice lacking ADK in the myeloid monocyte cells had reduced body weight and nasoanal length. The results of bone histomorphometric analysis revealed that bone mass was significantly decreased and osteoclastic parameters were increased in the study mice. Furthermore, in vitro cell culture revealed that inhibition of ADK function promoted osteoclast differentiation and bone resorption. Osteoclast­associated gene expression, including tartrate­resistant acid phosphatase, nuclear factor of activated T­cells, cytoplasmic 1, matrix metalloproteinase 9, Cathepsin K and calcitonin receptor, was also significantly increased. These results suggest that mice with ADK deficiency have reduced bone formation due to increased osteoclastogenesis and bone resorption. The present study provides further insight into the mechanism by which ADK serves a key role in bone metabolism.