Mutations in HFE are the most common cause of hereditary hemochromatosis (HH). HFE mutations result in reduced expression of hepcidin, a hepatic hormone, which negatively regulates iron absorption ...from the duodenum and iron release from macrophages. However, the mechanism by which HFE regulates hepcidin expression in hepatocytes is not well understood. It is known that the bone morphogenetic protein (BMP) pathway plays a central role in controlling hepcidin expression in the liver. Here we show that HFE overexpression increased Smad1/5/8 phosphorylation and hepcidin expression, whereas inhibition of BMP signaling abolished HFE-induced hepcidin expression in Hep3B cells. HFE was found to associate with ALK3, inhibiting ALK3 ubiquitination and proteasomal degradation and increasing ALK3 protein expression and accumulation on the cell surface. The 2 HFE mutants associated with HH, HFE C282Y and HFE H63D, regulated ALK3 protein ubiquitination and trafficking differently, but both failed to increase ALK3 cell-surface expression. Deletion of Hfe in mice resulted in a decrease in hepatic ALK3 protein expression. Our results provide evidence that HFE induces hepcidin expression via the BMP pathway: HFE interacts with ALK3 to stabilize ALK3 protein and increase ALK3 expression at the cell surface.
•HFE increases Smad1/5/8 phosphorylation and hepcidin expression, and inhibition of BMP signaling abolishes HFE-induced hepcidin expression.•HFE interacts with ALK3, inhibits ALK3 ubiquitination-proteasomal degradation, and increases ALK3 cell-surface expression.
Hepcidin is an antimicrobial peptide, which also negatively regulates iron in circulation by controlling iron absorption from dietary sources and iron release from macrophages. Hepcidin is ...synthesized mainly in the liver, where hepcidin is regulated by iron loading, inflammation and hypoxia. Recently, we have demonstrated that bone morphogenetic protein (BMP)-hemojuvelin (HJV)-SMAD signaling is central for hepcidin regulation in hepatocytes. Hepcidin is also expressed by macrophages. Studies have shown that hepcidin expression by macrophages increases following bacterial infection, and that hepcidin decreases iron release from macrophages in an autocrine and/or paracrine manner. Although previous studies have shown that lipopolysaccharide (LPS) can induce hepcidin expression in macrophages, whether hepcidin is also regulated by BMPs in macrophages is still unknown. Therefore, we examined the effects of BMP signaling on hepcidin expression in RAW 264.7 and J774 macrophage cell lines, and in primary peritoneal macrophages. We found that BMP4 or BMP6 alone did not have any effect on hepcidin expression in macrophages although they stimulated Smad1/5/8 phosphorylation and Id1 expression. In the presence of LPS, however, BMP4 and BMP6 were able to stimulate hepcidin expression in macrophages, and this stimulation was abolished by the NF-κB inhibitor Ro1069920. These results suggest that hepcidin expression is regulated differently in macrophages than in hepatocytes, and that BMPs regulate hepcidin expression in macrophages in a LPS-NF-κB dependent manner.
Concussion is a serious health concern. Concussion in athletes is of particular interest with respect to the relationship of concussion exposure to risk of chronic traumatic encephalopathy (CTE), a ...neurodegenerative condition associated with altered cognitive and psychiatric functions and profound tauopathy. However, much remains to be learned about factors other than cumulative exposure that could influence concussion pathogenesis. Approximately 20% of CTE cases report a history of substance use including androgenic-anabolic steroids (AAS). How acute, chronic, or historical AAS use may affect the vulnerability of the brain to concussion is unknown. We therefore tested whether antecedent AAS exposure in young, male C57Bl/6 mice affects acute behavioral and neuropathological responses to mild traumatic brain injury (TBI) induced with the CHIMERA (Closed Head Impact Model of Engineered Rotational Acceleration) platform. Male C57Bl/6 mice received either vehicle or a cocktail of three AAS (testosterone, nandrolone and 17α-methyltestosterone) from 8-16 weeks of age. At the end of the 7th week of treatment, mice underwent two closed-head TBI or sham procedures spaced 24 h apart using CHIMERA. Post-repetitive TBI (rTBI) behavior was assessed for 7 d followed by tissue collection. AAS treatment induced the expected physiological changes including increased body weight, testicular atrophy, aggression and downregulation of brain 5-HT1B receptor expression. rTBI induced behavioral deficits, widespread axonal injury and white matter microgliosis. While AAS treatment did not worsen post-rTBI behavioral changes, AAS-treated mice exhibited significantly exacerbated axonal injury and microgliosis, indicating that AAS exposure can alter neuronal and innate immune responses to concussive TBI.
Traumatic brain injury (TBI) is an established risk factor for neurodegenerative diseases. In this study, we used the Closed Head Injury Model of Engineered Rotational Acceleration (CHIMERA) to ...investigate the effects of a single high-energy TBI in rTg4510 mice, a mouse model of tauopathy. Fifteen male rTg4510 mice (4 mo) were impacted at 4.0 J using interfaced CHIMERA and were compared to sham controls. Immediately after injury, the TBI mice showed significant mortality (7/15; 47%) and a prolonged duration of loss of the righting reflex. At 2 mo post-injury, surviving mice displayed significant microgliosis (Iba1) and axonal injury (Neurosilver). Western blotting indicated a reduced p-GSK-3β (S9):GSK-3β ratio in TBI mice, suggesting chronic activation of tau kinase. Although longitudinal analysis of plasma total tau suggested that TBI accelerates the appearance of tau in the circulation, there were no significant differences in brain total or p-tau levels, nor did we observe evidence of enhanced neurodegeneration in TBI mice compared to sham mice. In summary, we showed that a single high-energy head impact induces chronic white matter injury and altered GSK-3β activity without an apparent change in post-injury tauopathy in rTg4510 mice.
Purpose: Nonviolent communication (NVC) has been increasingly recognized as a potentially beneficial approach that could promote empathy, resolve conflicts, and improve psychosocial well-being. No ...validated measure is available to assess or quantify NVC-specific characteristics or behaviors. This paper describes the development and pilot psychometric evaluation of a self-report measure for assessing behaviors characteristic of NVC (e.g., awareness of feelings, honest self-expression). Method: We analyzed data in an online convenience sample of young adults (N = 205). Results: The 7-item Nonviolent Communication Behaviors Scale (NVCBS) was found to have satisfactory internal consistency (α = 0.789 to 0.810), good test-retest reliability (ICC = 0.781) and a single-factor structure. The NVCBS was also positively correlated with empathy while negatively correlated with negative beliefs about emotions, demonstrating its construct validity. Discussion: The study provides a reliable and valid measure of NVC behaviors which can facilitate future studies on NVC. Directions for future research are discussed.
The impacts of adverse childhood experiences (ACEs) have been well documented. One possible consequence of ACEs is dissociation, which is a major feature of post-traumatic psychopathology and is also ...associated with considerable impairment and health care costs. Although ACEs are known to be associated with both psychoform and somatoform dissociation, much less is known about the mechanisms behind this relationship. Little is known about whether social and interpersonal factors such as family environments would moderate the relationship between ACEs and somatoform dissociation. This paper discusses the importance of having a positive and healthy family environment in trauma recovery. We then report the findings of a preliminary study in which we examined whether the association between ACEs and somatoform dissociation would be moderated by family well-being in a convenience sample of Hong Kong adults (N = 359). The number of ACEs was positively associated with somatoform dissociative symptoms, but this association was moderated by the level of family well-being. The number of ACEs was associated with somatoform dissociation only when the family well-being scores were low. These moderating effects were medium. The findings point to the potential importance of using family education and intervention programs to prevent and treat trauma-related dissociative symptoms, but further investigation is needed.
Traumatic brain injury (TBI) is a major worldwide healthcare problem. Despite promising outcomes from many preclinical studies, the failure of several clinical studies to identify effective ...therapeutic and pharmacological approaches for TBI suggests that methods to improve the translational potential of preclinical studies are highly desirable. Rodent models of TBI are increasingly in demand for preclinical research, particularly for closed head injury (CHI), which mimics the most common type of TBI observed clinically. Although seemingly simple to establish, CHI models are particularly prone to experimental variability. Promisingly, bioengineering-oriented research has advanced our understanding of the nature of the mechanical forces and resulting head and brain motion during TBI. However, many neuroscience-oriented laboratories lack guidance with respect to fundamental biomechanical principles of TBI. Here, we review key historical and current literature that is relevant to the investigation of TBI from clinical, physiological and biomechanical perspectives, and comment on how the current challenges associated with rodent TBI models, particularly those involving CHI, could be improved.
Purpose
Initial graft tensioning is important in anterior cruciate ligament reconstruction (ACLR), but its effect on graft healing is still not clear. Since all previous animal studies on graft ...tensioning used bone–patellar tendon–bone, this study aimed to investigate the effect of initial graft tensioning on ACLR using tendon graft.
Methods
Fifty-five Sprague–Dawley rats underwent ACLR using flexor digitorum longus tendon graft. A constant force of 2 or 4 N was applied during graft fixation. At 0, 2, and 6 weeks, knee samples were harvested (
n
= 6) for static knee laxity test and graft pull-out test. Histological examination was performed at 2 and 6 weeks post-injury (
n
= 4).
Results
At time zero, knee laxity was restored by ACLR with 2 or 4 N tensioning as compared to ACL-deficient group (
p
< 0.001), and the 4 N group exhibited a better restoration as compared to 2 N group (
p
= 0.031). At week 2 post-operation, the 4 N group still exhibited a better restoration in knee laxity (
p
= 0.001) and knee stiffness (
p
= 0.002) than the 2 N group; the graft pull-out force (
p
= 0.032) and stiffness (
p
= 0.010) were also higher. At week 6 post-operation, there was no significant difference between the 2 and 4 N group in knee laxity and graft pull-out strength. Histological examination showed that the beneficial effect of higher initial graft tension may be contributed by maintenance of graft integrity at mid-substance and reduction in adverse peri-graft bone changes in the femoral tunnel region.
Conclusions
A higher initial graft tension favours the restoration of knee laxity and promotes graft healing in ACLR using free tendon graft in the rat model.
The annual incidence of traumatic brain injury (TBI) in the United States is over 2.5 million, with approximately 3-5 million people living with chronic sequelae. Compared with moderate-severe TBI, ...the long-term effects of mild TBI (mTBI) are less understood but important to address, particularly for contact sport athletes and military personnel who have high mTBI exposure. The purpose of this study was to determine the behavioural and neuropathological phenotypes induced by the Closed-Head Impact Model of Engineered Rotational Acceleration (CHIMERA) model of mTBI in both wild-type (WT) and APP/PS1 mice up to 8 months post-injury.
Male WT and APP/PS1 littermates were randomized to sham or repetitive mild TBI (rmTBI; 2 × 0.5 J impacts 24 h apart) groups at 5.7 months of age. Animals were assessed up to 8 months post-injury for acute neurological deficits using the loss of righting reflex (LRR) and Neurological Severity Score (NSS) tasks, and chronic behavioural changes using the passive avoidance (PA), Barnes maze (BM), elevated plus maze (EPM) and rotarod (RR) tasks. Neuropathological assessments included white matter damage; grey matter inflammation; and measures of Aβ levels, deposition, and aducanumab binding activity.
The very mild CHIMERA rmTBI conditions used here produced no significant acute neurological or motor deficits in WT and APP/PS1 mice, but they profoundly inhibited extinction of fear memory specifically in APP/PS1 mice over the 8-month assessment period. Spatial learning and memory were affected by both injury and genotype. Anxiety and risk-taking behaviour were affected by injury but not genotype. CHIMERA rmTBI induced chronic white matter microgliosis, axonal injury and astrogliosis independent of genotype in the optic tract but not the corpus callosum, and it altered microgliosis in APP/PS1 amygdala and hippocampus. Finally, rmTBI did not alter long-term tau, Aβ or amyloid levels, but it increased aducanumab binding activity.
CHIMERA is a useful model to investigate the chronic consequences of rmTBI, including behavioural abnormalities consistent with features of post-traumatic stress disorder and inflammation of both white and grey matter. The presence of human Aβ greatly modified extinction of fear memory after rmTBI.
Glial fibrillary acidic protein (GFAP) has emerged as a promising fluid biomarker for several neurological indications including traumatic brain injury (TBI), a leading cause of death and disability ...worldwide. In humans, serum or plasma GFAP levels can predict brain abnormalities including hemorrhage on computed tomography (CT) scans and magnetic resonance imaging (MRI). However, assays to quantify plasma or serum GFAP in preclinical models are not yet available.
We developed and validated a novel sensitive GFAP immunoassay assay for mouse plasma on the Meso Scale Discovery immunoassay platform and validated assay performance for robustness, precision, limits of quantification, dilutional linearity, parallelism, recovery, stability, selectivity, and pre-analytical factors. To provide proof-of-concept data for this assay as a translational research tool for TBI and Alzheimer's disease (AD), plasma GFAP was measured in mice exposed to TBI using the Closed Head Impact Model of Engineered Rotational Acceleration (CHIMERA) model and in APP/PS1 mice with normal or reduced levels of plasma high-density lipoprotein (HDL).
We performed a partial validation of our novel assay and found its performance by the parameters studied was similar to assays used to quantify human GFAP in clinical neurotrauma blood specimens and to assays used to measure murine GFAP in tissues. Specifically, we demonstrated an intra-assay CV of 5.0%, an inter-assay CV of 7.2%, a lower limit of detection (LLOD) of 9.0 pg/mL, a lower limit of quantification (LLOQ) of 24.8 pg/mL, an upper limit of quantification (ULOQ) of at least 16,533.9 pg/mL, dilution linearity of calibrators from 20 to 200,000 pg/mL with 90-123% recovery, dilution linearity of plasma specimens up to 32-fold with 96-112% recovery, spike recovery of 67-100%, and excellent analyte stability in specimens exposed to up to 7 freeze-thaw cycles, 168 h at 4 °C, 24 h at room temperature (RT), or 30 days at - 20 °C. We also observed elevated plasma GFAP in mice 6 h after TBI and in aged APP/PS1 mice with plasma HDL deficiency. This assay also detects GFAP in serum.
This novel assay is a valuable translational tool that may help to provide insights into the mechanistic pathophysiology of TBI and AD.
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