β-Arrestin 2 protects against neurological function defects in HSV-1-induced encephalitis mice

Small Animal Models to Study Herpes Simplex Virus Infections

Herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) are two of the most prevalent human viruses worldwide. They are known to cause a variety of diseases including genital herpes, meningitis, encephalitis, cold sores and herpes stromal keratitis. The seropositive rate for HSV-1 is around 90%, whereas for HSV-2 it remains around 20-25% for the general adult population. The infections caused by these viruses remain difficult to study because a large proportion of infected individuals are asymptomatic. Furthermore, given the neurotropic characteristics of the virus, studies aimed at understanding the complex pathogenesis in humans is difficult. As a result, animal models have been developed to understand several characteristics of HSV biology, pathogenesis, disease and host responses to infection. These models are also commonly used as the first evaluation of new drugs and vaccines. There are several well-established animal models to study infection with HSV, including mice, guinea pigs and rabbits. Variables within the animal models depend on the species of animal, route of infection, viral strain, dosage, etc. This review aims at summarizing the most commonly used animal models to study HSV pathogenesis and therapies.

Effect of resveratrol on herpesvirus encephalitis: Evidences for its mechanisms of action

BACKGROUND

Herpes simplex virus type 1 (HSV-1)-induced herpes simplex encephalitis (HSE) has a high mortality rate in clinically immunocompromised patients, while recovered patients often experience neurological sequelae due to neuroinflammation. Nucleoside drugs and nucleoside analogues such as acyclovir and ganciclovir are mainly used in clinical treatment, and the emergence of resistant viral strains makes the development of new anti-herpesvirus encephalitis drugs urgent. Resveratrol is a multifunctional, plant-derived bioactive compound and its antiviral potential is attracting much attention.

PURPOSE

This study aimed to investigate the anti-HSV-1 mechanism of resveratrol in microglial cells and in the HSE mouse model.

METHODS

The antiviral effect of resveratrol on HSV-1 infection was investigated by plaque assay, virus titer, immunofluorescence, Western blot and time-of-addition assay. The influence of resveratrol on stimulator of interferon gene (STING)/Nuclear Factor kappa B (NF-κB) signaling pathway-mediated neuroinflammation was examined by Western blot, RT-qPCR and ELISA. The interaction between resveratrol and STING/heat shock protein 90 beta (HSP90β) was evaluated by molecular modeling, co-immunoprecipitation, and drug affinity responsive target stability assay. The therapeutic effect of resveratrol on HSE was evaluated in the HSE mouse model by analyzing weight loss, neurodegenerative symptoms and histopathological scores.

RESULTS

Resveratrol inhibited the early process of HSV-1 infection, and interfered with the STING/NF-κB signaling pathway to attenuate HSV-1-induced neuroinflammation and microglial M1 polarization, independent of its classical target Sirtuin1. Mechanistically, resveratrol completely bound to Glu515 and Lys491 of HSP90β, thus disrupting the HSP90β-STING interaction and promoting STING degradation. Resveratrol also significantly alleviated viral encephalitis and neuroinflammation caused by HSV-1 in the HSE mouse model.

CONCLUSION

Resveratrol acted as a non-classical HSP90β inhibitor, binding to the STING-HSP90β interaction site to promote STING degradation and attenuate HSV-1-induced encephalitis and neuroinflammation. These findings suggest the alternative strategy of targeting HSP90β and resveratrol-mediated inhibition of HSP90β as a potential antiviral approach.

Intestinal dysbiosis exacerbates susceptibility to the anti-NMDA receptor encephalitis-like phenotype by changing blood brain barrier permeability and immune homeostasis

Changes in the intestinal microbiota have been observed in patients with anti-N-methyl-D-aspartate receptor encephalitis (NMDARE). However, whether and how the intestinal microbiota is involved in the pathogenesis of NMDARE susceptibility needs to be demonstrated. Here, we first showed that germ-free (GF) mice that underwent fecal microbiota transplantation (FMT) from NMDARE patients, whose fecal microbiota exhibited low short-chain fatty acid content, decreased abundance of Lachnospiraceae, and increased abundance of Verrucomicrobiota, Akkermansia, Parabacteroides, Oscillospirales, showed significant behavioral deficits. Then, these FMT mice were actively immunized with an amino terminal domain peptide from the GluN1 subunit (GluN1356-385) to mimic the pathogenic process of NMDARE. We found that FMT mice showed an increased susceptibility to an encephalitis-like phenotype characterized by more clinical symptoms, greater pentazole (PTZ)-induced susceptibility to seizures, and higher levels of T2 weighted image (T2WI) hyperintensities following immunization. Furthermore, mice with dysbiotic microbiota had impaired blood-brain barrier integrity and a proinflammatory condition. In NMDARE-microbiota recipient mice, the levels of Evan's blue (EB) dye extravasation increased, ZO-1 and claudin-5 expression decreased, and the levels of proinflammatory cytokines (IL-1, IL-6, IL-17, TNF-α and LPS) increased. Finally, significant brain inflammation, mainly in hippocampal and cortical regions, with modest neuroinflammation, immune cell infiltration, and reduced expression of NMDA receptors were observed in NMDARE microbiota recipient mice following immunization. Overall, our findings demonstrated that intestinal dysbiosis increased NMDARE susceptibility, suggesting a new target for limiting the occurrence of the severe phenotype of NMDARE.

Immunopathology of herpes simplex virus-associated neuroinflammation: Unveiling the mysteries

The immunopathology of herpes simplex virus (HSV)-associated neuroinflammation is a captivating and intricate field of study within the scientific community. HSV, renowned for its latent infection capability, gives rise to a spectrum of neurological expressions, ranging from mild symptoms to severe encephalitis. The enigmatic interplay between the virus and the host's immune responses profoundly shapes the outcome of these infections. This review delves into the multifaceted immune reactions triggered by HSV within neural tissues, intricately encompassing the interplay between innate and adaptive immunity. Furthermore, this analysis delves into the delicate equilibrium between immune defence and the potential for immunopathology-induced neural damage. It meticulously dissects the roles of diverse immune cells, cytokines, and chemokines, unravelling the intricacies of neuroinflammation modulation and its subsequent effects. By exploring HSV's immune manipulation and exploitation mechanisms, this review endeavours to unveil the enigmas surrounding the immunopathology of HSV-associated neuroinflammation. This comprehensive understanding enhances our grasp of viral pathogenesis and holds promise for pioneering therapeutic strategies designed to mitigate the neurological ramifications of HSV infections.

β-Arrestin 2 acts an adaptor protein that facilitates viral replication in silkworm

β-Arrestin 2 is known to be a widely distributed adaptor protein in mammals but its function has never been reported in Lepidoptera insects. Herein, the β-Arrestin 2 (BmArrestin 2) gene from silkworm was cloned and characterized. The spatiotemporal expression level of BmArrestin 2 was highest in the gonads at the 3rd day of 5th instar, whereas the highest and lowest abundance of BmArrestin 2 were identified in the tracheal and testis, respectively. BmArrestin 2 is mainly distributed in the cytoplasm. Furthermore, in BmN cells，overexpression of BmArrestin 2 promoted Bombyx mori nucleopolyhedrovirus (BmNPV) and B. mori cytoplasmic polyhedrosis virus (BmCPV) replication as the increment of the concentration of plasmid transfection, whereas silencing the gene with specific siRNA inhibited viral replication. Replication of BmNPV and BmCPV also was weakened using BmArrestin 2 antiserum as the increment of the concentration. Immunofluorescent staining revealed the invasion of recombinant BmNPV or BmCPV was decreased after blocking endogenous BmArrestin 2. On the other hand, BmArrestin 2 co-localizes with recombinant BmNPV and BmCPV virions in BmN cells. These results suggest that BmArrestin 2 may represent a novel target for antiviral strategies, as it is an adaptor protein that plays a key role in virus replication.

β-arrestin-2 alleviates rheumatoid arthritis injury by suppressing NLRP3 inflammasome activation and NF- κB pathway in macrophages

Rheumatoid arthritis (RA) is a chronic inflammatory joint disorder that inflicts damage to the joints of the hands and wrist. The aim of this study was to investigate the protective effect of β-Arrestin-2 (βArr2) on RA in vivo and in vitro. The βArr2 adenovirus (βArr2-Ad) or the control (Con-Ad) was injected into the ankle joint cavity of collagen-induced arthritis (CIA) mice. According to the results, an improvement was shown in the symptoms and pathological injury of RA after an upregulation of βArr2. Correspondingly, the inflammatory response was attenuated, as evidenced by the decreased serum pro-inflammatory cytokines levels and NF-κB pathway-related proteins. Nucleotide-binding domain leucine-rich repeat and pyrin domain containing receptor 3 (NLRP3) inflammasome activation was inhibited in CIA mice treated with βArr2-Ad injection, as reflected by the diminished IL-18 level and declined protein levels of inflammasome components in the ankle joint. Likewise, the anti-inflammatory effect of macrophages was also validated by in vitro experiments. In summary, βArr2 effectively ameliorates ankle inflammation in CIA mice via NF-κB/NLRP3 inflammasome, providing theoretical and clinical basis for RA therapy.

Role of Thrombin in Central Nervous System Injury and Disease

Thrombin is a Na+-activated allosteric serine protease of the chymotrypsin family involved in coagulation, inflammation, cell protection, and apoptosis. Increasingly, the role of thrombin in the brain has been explored. Low concentrations of thrombin are neuroprotective, while high concentrations exert pathological effects. However, greater attention regarding the involvement of thrombin in normal and pathological processes in the central nervous system is warranted. In this review, we explore the mechanisms of thrombin action, localization, and functions in the central nervous system and describe the involvement of thrombin in stroke and intracerebral hemorrhage, neurodegenerative diseases, epilepsy, traumatic brain injury, and primary central nervous system tumors. We aim to comprehensively characterize the role of thrombin in neurological disease and injury.

Identification of a β-Arrestin 2 Mutation Related to Autism by Whole-Exome Sequencing

Autism spectrum disorder (ASD) is a complex neurological disease characterized by impaired social communication and interaction skills, rigid behavior, decreased interest, and repetitive activities. The disease has a high degree of genetic heterogeneity, and the genetic cause of ASD in many autistic individuals is currently unclear. In this study, we report a patient with ASD whose clinical features included social interaction disorder, communication disorder, and repetitive behavior. We examined the patient's genetic variation using whole-exome sequencing technology and found new de novo mutations. After analysis and evaluation, ARRB2 was identified as a candidate gene. To study the potential contribution of the ARRB2 gene to the human brain development and function, we first evaluated the expression profile of this gene in different brain regions and developmental stages. Then, we used weighted gene coexpression network analysis to analyze the associations between ARRB2 and ASD risk genes. Additionally, the spatial conformation and stability of the ARRB2 wild type and mutant proteins were examined by simulations. Then, we further established a mouse model of ASD. The results showed abnormal ARRB2 expression in the mouse ASD model. Our study showed that ARRB2 may be a risk gene for ASD, but the contribution of de novo ARRB2 mutations to ASD is unclear. This information will provide references for the etiology of ASD and aid in the mechanism-based drug development and treatment.