Activation of endogenous retrovirus triggers microglial immuno-inflammation and contributes to negative emotional behaviors in mice with chronic stress

Methylome-wide association study of adolescent depressive episode with psychotic symptoms and childhood trauma

BACKGROUND

Emerging evidence suggests that DNA methylation is crucial in the mental disorder pathophysiology. The current study attempted to identify the dysregulation of DNA methylation patterns in adolescent patients suffering from depressive episodes (DE) while considering the impact of various subtypes, including psychotic symptoms and a history of childhood trauma.

METHODS

The study included 67 patients with DE and 30 healthy controls (HCs) subjects. Severe depressive episode (SDE) patients were grouped according to psychotic symptoms, such as SDE with vs. SDE without psychotic symptoms (cases 29 vs. 21). The Childhood Trauma Questionnaire-Short Form helped assess childhood trauma among all patients. Thus, all the patients were divided into adolescent DE experiencing ≥ two trauma types vs. experiencing ≤ one trauma type (cases, 50 vs. 17). Methylome-wide analysis was conducted on peripheral blood to identify methylation differences in CpG sites for three comparisons: DE vs. HCs, SDE patients with vs. without psychotic symptoms, and DE patients having 0-1 type of childhood trauma vs. those having ≥two types of childhood trauma.

RESULTS

Adolescent DE patients demonstrated a predominant trend of lower methylation levels than HCs, with 259 hypermethylated and 3956 hypomethylated sites. Differentially hypomethylated sites involve related genes such as FKBP5, BDNF, NR3C1, GABRB3, SHANK1, SLC38A1, SLC6A18, CHRNB1, CTNNA2, CTTNBP2, etc. All these genes could be involved in DE pathogenesis. Significant DNA methylation differences could be observed in SDE subgroups with and without psychotic symptoms (e.g., genes like DTNB, CNTN1, CTNNA2), along with those DE patients having 0-1 type of childhood trauma compared to those with ≥2 types (e.g., VWA3B, SYT10, SDK2, CAMSAP3). Many significant methylated sites were associated with genes involved in brain development, highlighting the potential pathophysiological mechanisms linked with DE and its subtypes, such as psychotic symptoms and childhood trauma.

CONCLUSION

Our findings suggest that differential DNA methylation is associated with the pathophysiology of DE, as well as the presence of psychotic symptoms and a history of childhood trauma. These blood-based methylation patterns may serve as biomarkers for DE and shed light on underlying mechanisms across these subtypes.

Dimethyl fumarate ameliorates chronic stress-induced anxiety-like behaviors by decreasing neuroinflammation and neuronal activity in the amygdala

BACKGROUND

Chronic stress-induced neuroinflammation plays a pivotal role in the development and exacerbation of mental disorders, such as anxiety and depression. Dimethyl Fumarate (DMF), an effective therapeutic agent approved for the treatment of multiple sclerosis, has been widely reported to display anti-inflammatory and anti-oxidative effects. However, the impact of DMF on chronic stress-induced anxiety disorders and the exact underlying mechanisms remain largely unknown.

METHODS

We established a mouse model of chronic social defeat stress (CSDS). DMF was administered orally 1 h before daily stress session for 10 days in CSDS + DMF group. qRT-PCR and western blotting were used to analyze mRNA and protein expression of NLRP3, Caspase-1 and IL-1β. Immunofluorescence staining was carried out to detect the expression of Iba 1 and c-fos positive cells as well as morphological change of Iba 1+ microglia. Whole-cell patch-clamp recording was applied to evaluate synaptic transmission and intrinsic excitability of neurons.

RESULTS

DMF treatment significantly alleviated CSDS-induced anxiety-like behaviors in mice. Mechanistically, DMF treatment prevented CSDS-induced neuroinflammation by inhibiting the activation of microglia and NLRP3/Caspase-1/IL-1β signaling pathway in basolateral amygdala (BLA), a brain region important for emotional processing. Furthermore, DMF treatment effectively reversed the CSDS-caused disruption of excitatory and inhibitory synaptic transmission balance, as well as the increased intrinsic excitability of BLA neurons.

CONCLUSIONS

Our findings provide new evidence that DMF may exert anxiolytic effect by preventing CSDS-induced activation of NLRP3/Caspase-1/IL-1β signaling pathway and alleviating hyperactivity of BLA neurons.

Inflammatory damage caused by Echovirus 30 in the suckling mouse brain and HMC3 cells

Echovirus 30 (E30), a member of the species B Enterovirus family, is a primary pathogen responsible for aseptic meningitis and encephalitis. E30 is associated with severe nervous system diseases and is a primary cause of child illness, disability, and even mortality. However, the mechanisms underlying E30-induced brain injury remain poorly understood. In this study, we used a neonatal mouse model of E30 to investigate the possible mechanisms of brain injury. E30 infection triggered the activation of microglia in the mouse brain and efficiently replicated within HMC3 cells. Subsequent transcriptomic analysis revealed inflammatory activation of microglia in response to E30 infection. We also detected a significant upregulation of polo-like kinase 1 (PLK1) and found that its inhibition could limit E30 infection in a sucking mouse model. Collectively, E30 infection led to brain injury in a neonatal mouse model, which may be related to excessive inflammatory responses. Our findings highlight the intricate interplay between E30 infection and neurological damage, providing crucial insights that could guide the development of interventions and strategies to address the severe clinical manifestations associated with this pathogen.

Plasma circRNA HIPK2 as a putative biomarker for the diagnosis and prediction of therapeutic effects in major depressive disorder

BACKGROUND

Circular RNAs (circRNAs) are a prevalent type of non-coding RNAs exhibiting extensive expression in mammalian cells. Owing to their involvement in diverse pathophysiological mechanisms of major depressive disorder (MDD) and their inherent stability in peripheral blood, circRNAs have emerged as potential biomarkers of considerable significance. This study aimed to identify and validate circular RNA HIPK2 (circHIPK2) in MDD patients and to investigate its potential as a biomarker for the diagnosis and prognosis of MDD.

METHODS

Patients with MDD (n = 81) and healthy controls (HCs) (n = 48) were recruited for our study (October 2022 to June 2023). The expression of circHIPK2 in plasma was assessed using absolute quantitative polymerase chain reaction (qPCR).

RESULTS

The expression of circHIPK2 in plasma of patients with MDD exhibited a significant increase compared to HCs. The circHIPK2 levels showed an area under the curve (AUC) of 0.796, corresponding to a specificity of 97.9% and a sensitivity of 60.4% in diagnosing MDD. Additionally, the rate of change in circHIPK2 over a 14-day period exhibited an AUC curve of 0.819, indicating its predictive value for antidepressive effects.

CONCLUSIONS

CircHIPK2 could serve as a potential biomarker for diagnosing MDD and predicting therapeutic effects of MDD.

COVID-19. Biology, pathophysiology, and immunology: a pathologist view

Even if the SARS-CoV-2 pandemic has been declared over, several risks and clinical problems remain to be faced, including long-COVID sequelae and possible outbreaks of pathogenic variants. Intense research on COVID-19 has provided in these few years a striking amount of data covering different fields and disciplines, which can help to provide a knowledge shield against new potential infective spreads, and may also potentially be applied to other fields of medicine, including oncology and neurology. Nevertheless, areas of uncertainty still remain regarding the pathogenic mechanisms that subtend the multifaceted manifestations of the disease. To better clarify the pathogenesis of the disease, a systematic multidisciplinary evaluation of the many mechanisms involved in COVID-19 is mandatory, including clinical, physiological, radiological, immunological and pathological studies. In COVID-19 syndrome the pathological studies have been mainly performed on autopsy cases, and only a few studies are available on biopsies. Nevertheless, these studies have provided relevant information that can substantially contribute to decipher the complex scenario characterizing the different forms of COVID-19 and long-COVID-19. In this review the data provided by pathological investigations are recapitulated and discussed, in the light of different hypothesis and data provided by clinical, physiological and immunological data.