The β-adrenergic receptor blocker and anti-inflammatory drug propranolol mitigates brain cytokine expression in a long-term model of Gulf War Illness

Nerve agent exposure and physiological stress alter brain microstructure and immune profiles after inflammatory challenge in a long-term rat model of Gulf War Illness

Gulf War Illness (GWI) is a disorder experienced by many veterans of the 1991 Gulf War, with symptoms including fatigue, chronic pain, respiratory and memory problems. Exposure to toxic chemicals during the war, such as oil well fire smoke, pesticides, physiological stress, and nerve agents, is thought to have triggered abnormal neuroinflammatory responses that contribute to GWI. Previous studies have examined the acute effects of combined physiological stress and chemical exposures using GWI rodent models and presented findings related to neuroinflammation and changes in diffusion magnetic resonance imaging (MRI) measures, suggesting a neuroimmune basis for GWI. In the current study, using ex vivo MRI, cytokine mRNA expression, and immunohistological analyses of brain tissues, we examined the brain structure and immune function of a chronic rat model of GWI. Our data showed that a combination of long-term corticosterone treatment (to mimic high physiological stress) and diisopropyl fluorophosphate exposure (to mimic sarin exposure) primed the response to subsequent systemic immune challenge with lipopolysaccharide resulting in elevations of multiple cytokine mRNAs, an increased activated glial population, and disrupted brain microstructure in the cingulate cortex and hippocampus compared to control groups. Our findings support the critical role of neuroinflammation, dysregulated glial activation, and their relationship to disrupted brain microstructural integrity in the pathophysiology of GWI and highlight the unique consequences of long-term combined exposures on brain biochemistry and structural connectivity.

Chronic Corticosterone Administration-Induced Mood Disorders in Laboratory Rodents: Features, Mechanisms, and Research Perspectives

Mood disorders mainly affect the patient's daily life, lead to suffering and disability, increase the incidence rate of many medical illnesses, and even cause a trend of suicide. The glucocorticoid (GC)-mediated hypothalamus-pituitary-adrenal (HPA) negative feedback regulation plays a key role in neuropsychiatric disorders. The balance of the mineralocorticoid receptor (MR)/glucocorticoid receptor (GR) level contributes to maintaining the homeostasis of the neuroendocrine system. Consistently, a chronic excess of GC can also lead to HPA axis dysfunction, triggering anxiety, depression, memory loss, and cognitive impairment. The animal model induced by chronic corticosterone (CORT) administration has been widely adopted because of its simple replication and strong stability. This review summarizes the behavioral changes and underlying mechanisms of chronic CORT administration-induced animal models, including neuroinflammatory response, pyroptosis, oxidative stress, neuroplasticity, and apoptosis. Notably, CORT administration at different doses and cycles can destroy the balance of the MR/GR ratio to make dose-dependent effects of CORT on the central nervous system (CNS). This work aims to offer an overview of the topic and recommendations for future cognitive function research.

FDA-approved cannabidiol [Epidiolex®] alleviates Gulf War Illness-linked cognitive and mood dysfunction, hyperalgesia, neuroinflammatory signaling, and declined neurogenesis

BACKGROUND

Chronic Gulf War Illness (GWI) is characterized by cognitive and mood impairments, as well as persistent neuroinflammation and oxidative stress. This study aimed to investigate the efficacy of Epidiolex®, a Food and Drug Administration (FDA)-approved cannabidiol (CBD), in improving brain function in a rat model of chronic GWI.

METHODS

Six months after exposure to low doses of GWI-related chemicals [pyridostigmine bromide, N,N-diethyl-meta-toluamide (DEET), and permethrin (PER)] along with moderate stress, rats with chronic GWI were administered either vehicle (VEH) or CBD (20 mg/kg, oral) for 16 weeks. Neurobehavioral tests were conducted on 11 weeks after treatment initiation to evaluate the performance of rats in tasks related to associative recognition memory, object location memory, pattern separation, and sucrose preference. The effect of CBD on hyperalgesia was also examined. The brain tissues were processed for immunohistochemical and molecular studies following behavioral tests.

RESULTS

GWI rats treated with VEH exhibited impairments in all cognitive tasks and anhedonia, whereas CBD-treated GWI rats showed improvements in all cognitive tasks and no anhedonia. Additionally, CBD treatment alleviated hyperalgesia in GWI rats. Analysis of hippocampal tissues from VEH-treated rats revealed astrocyte hypertrophy and increased percentages of activated microglia presenting NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) complexes as well as elevated levels of proteins involved in NLRP3 inflammasome activation and Janus kinase/signal transducers and activators of the transcription (JAK/STAT) signaling. Furthermore, there were increased concentrations of proinflammatory and oxidative stress markers along with decreased neurogenesis. In contrast, the hippocampus from CBD-treated GWI rats displayed reduced levels of proteins mediating the activation of NLRP3 inflammasomes and JAK/STAT signaling, normalized concentrations of proinflammatory cytokines and oxidative stress markers, and improved neurogenesis. Notably, CBD treatment did not alter the concentration of endogenous cannabinoid anandamide in the hippocampus.

CONCLUSIONS

The use of an FDA-approved CBD (Epidiolex®) has been shown to effectively alleviate cognitive and mood impairments as well as hyperalgesia associated with chronic GWI. Importantly, the improvements observed in rats with chronic GWI in this study were attributed to the ability of CBD to significantly suppress signaling pathways that perpetuate chronic neuroinflammation.

A Projectile Concussive Impact Model Produces Neuroinflammation in Both Mild and Moderate-Severe Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of death and disability and is experienced by nearly 3 million people annually as a result of falls, vehicular accidents, or from being struck by or against an object. While TBIs can range in severity, the majority of injuries are considered to be mild. However, TBI of any severity has the potential to have long-lasting neurological effects, including headaches, cognitive/memory impairments, mood dysfunction, and fatigue as a result of neural damage and neuroinflammation. Here, we modified a projectile concussive impact (PCI) model of TBI to deliver a closed-head impact with variable severity dependent on the material of the ball-bearing projectile. Adult male Sprague Dawley rats were evaluated for neurobehavioral, neuroinflammatory, and neural damage endpoints both acutely and longer-term (up to 72 h) post-TBI following impact with either an aluminum or stainless-steel projectile. Animals that received TBI using the stainless-steel projectile exhibited outcomes strongly correlated to moderate-severe TBI, such as prolonged unconsciousness, impaired neurobehavior, increased risk for hematoma and death, as well as significant neuronal degeneration and neuroinflammation throughout the cortex, hippocampus, thalamus, and cerebellum. In contrast, rats that received TBI with the aluminum projectile exhibited characteristics more congruous with mild TBI, such as a trend for longer periods of unconsciousness in the absence of neurobehavioral deficits, a lack of neurodegeneration, and mild neuroinflammation. Moreover, alignment of cytokine mRNA expression from the cortex of these rats with a computational model of neuron-glia interaction found that the moderate-severe TBI produced by the stainless-steel projectile strongly associated with the neuroinflammatory state, while the mild TBI existed in a state between normal and inflammatory neuron-glia interactions. Thus, these modified PCI protocols are capable of producing TBIs that model the clinical and experimental manifestations associated with both moderate-severe and mild TBI producing relevant models for the evaluation of the potential underlying roles of neuroinflammation and other chronic pathophysiology in the long-term outcomes associated with TBI.

Pathophysiological basis and promise of experimental therapies for Gulf War Illness, a chronic neuropsychiatric syndrome in veterans

This article describes the pathophysiology and potential treatments for Gulf War Illness (GWI), which is a chronic neuropsychiatric illness linked to a combination of chemical exposures experienced by service personnel during the first Gulf War in 1991. However, there is currently no effective treatment for veterans with GWI. The article focuses on the current status and efficacy of existing therapeutic interventions in preclinical models of GWI, as well as potential perspectives of promising therapies. GWI stems from changes in brain and peripheral systems in veterans, leading to neurocognitive deficits, as well as physiological and psychological effects resulting from multifaceted changes such as neuroinflammation, oxidative stress, and neuronal damage. Aging not only renders veterans more susceptible to GWI symptoms, but also attenuates their immune capabilities and response to therapies. A variety of experimental models are being used to investigate the pathophysiology and develop therapies that have the ability to alleviate devastating symptoms. Over two dozen therapeutic interventions targeting neuroinflammation, mitochondrial dysfunction, neuronal injury, and neurogenesis are being tested, including agents such as curcumin, curcumin nanoparticles, monosodium luminol, melatonin, resveratrol, fluoxetine, rolipram, oleoylethanolamide, ketamine, levetiracetam, nicotinamide riboside, minocycline, pyridazine derivatives, and neurosteroids. Preclinical outcomes show that some agents have promise, including curcumin, resveratrol, and ketamine, which are being tested in clinical trials in GWI veterans. Neuroprotectants and other compounds such as monosodium luminol, melatonin, levetiracetam, oleoylethanolamide, and nicotinamide riboside appear promising for future clinical trials. Neurosteroids have been shown to have neuroprotective and disease-modifying properties, which makes them a promising medicine for GWI. Therefore, accelerated clinical studies are urgently needed to evaluate and launch an effective therapy for veterans displaying GWI.

Chemical exposures and suspected impact on Gulf War Veterans

Gulf War Illness (GWI) encompass a spectrum of maladies specific to troops deployed during the Persian Gulf War (1990-1991). There are several hypothesized factors believed to contribute to GWI, including (but not limited to) exposures to chemical agents and a foreign environment (e.g., dust, pollens, insects, and microbes). Moreover, the inherent stress associated with deployment and combat has been associated with GWI. While the etiology of GWI remains uncertain, several studies have provided strong evidence that chemical exposures, especially neurotoxicants, may be underlying factors for the development of GWI. This mini style perspective article will focus on some of the major evidence linking chemical exposures to GWI development and persistence decades after exposure.

Adrenoceptors as potential target for add-on immunomodulatory therapy in multiple sclerosis

This review summarizes recent findings related to the role of the sympathetic nervous system (SNS) in pathogenesis of multiple sclerosis (MS) and its commonly used experimental model - experimental autoimmune encephalomyelitis (EAE). They indicate that noradrenaline, the key end-point mediator of the SNS, acting through β-adrenoceptor, has a contributory role in the early stages of MS/EAE development. This stage is characterized by the SNS hyperactivity (increased release of noradrenaline) reflecting the net effect of different factors, such as the disease-associated inflammation, stress, vitamin D hypovitaminosis, Epstein-Barr virus infection and dysbiosis. Thus, the administration of propranolol, a non-selective β-adrenoceptor blocker, readily crossing the blood-brain barrier, to experimental rats before the autoimmune challenge and in the early (preclinical/prodromal) phase of the disease mitigates EAE severity. This phenomenon has been ascribed to the alleviation of neuroinflammation (due to attenuation of primarily microglial activation/proinflammatory functions) and the diminution of the magnitude of the primary CD4+ T-cell autoimmune response (the effect associated with impaired autoantigen uptake by antigen presenting cells and their migration into draining lymph nodes). The former is partly related to breaking of the catecholamine-dependent self-amplifying microglial feed-forward loop and the positive feedback loop between microglia and the SNS, leading to down-regulation of the SNS hyperactivity and its enhancing influence on microglial activation/proinflammatory functions and the magnitude of autoimmune response. The effects of propranolol are shown to be more prominent in male EAE animals, the phenomenon important as males (like men) are likely to develop clinically more severe disease. Thus, these findings could serve as a firm scientific background for formulation of a new sex-specific immune-intervention strategy for the early phases of MS (characterized by the SNS hyperactivity) exploiting anti-(neuro)inflammatory and immunomodulatory properties of propranolol and other relatively cheap and safe adrenergic drugs with similar therapeutic profile.

Sustainable Release of Propranolol Hydrochloride Laden with Biconjugated-Ufasomes Chitosan Hydrogel Attenuates Cisplatin-Induced Sciatic Nerve Damage in In Vitro/In Vivo Evaluation

Peripheral nerve injuries significantly impact patients' quality of life and poor functional recovery. Chitosan-ufasomes (CTS-UFAs) exhibit biomimetic features, making them a viable choice for developing novel transdermal delivery for neural repair. This study aimed to investigate the role of CTS-UFAs loaded with the propranolol HCl (PRO) as a model drug in enhancing sciatica in cisplatin-induced sciatic nerve damage in rats. Hence, PRO-UFAs were primed, embedding either span 20 or 60 together with oleic acid and cholesterol using a thin-film hydration process based on full factorial design (24). The influence of formulation factors on UFAs' physicochemical characteristics and the optimum formulation selection were investigated using Design-Expert® software. Based on the optimal UFA formulation, PRO-CTS-UFAs were constructed and characterized using transmission electron microscopy, stability studies, and ex vivo permeation. In vivo trials on rats with a sciatic nerve injury tested the efficacy of PRO-CTS-UFA and PRO-UFA transdermal hydrogels, PRO solution, compared to normal rats. Additionally, oxidative stress and specific apoptotic biomarkers were assessed, supported by a sciatic nerve histopathological study. PRO-UFAs and PRO-CTS-UFAs disclosed entrapment efficiency of 82.72 ± 2.33% and 85.32 ± 2.65%, a particle size of 317.22 ± 6.43 and 336.12 ± 4.9 nm, ζ potential of -62.06 ± 0.07 and 65.24 ± 0.10 mV, and accumulatively released 70.95 ± 8.14% and 64.03 ± 1.9% PRO within 6 h, respectively. Moreover, PRO-CTS-UFAs significantly restored sciatic nerve structure, inhibited the cisplatin-dependent increase in peripheral myelin 22 gene expression and MDA levels, and further re-established sciatic nerve GSH and CAT content. Furthermore, they elicited MBP re-expression, BCL-2 mild expression, and inhibited TNF-α expression. Briefly, our findings proposed that CTS-UFAs are promising to enhance PRO transdermal delivery to manage sciatic nerve damage.

Stressor-Specific Microbiota Intervention

To date, mental disorders are diagnosed and treated by the subjective judgment of psychiatrists based on diagnostic criteria and treatment guidelines, respectively. Mental disorders are heterogeneous illnesses with a substantial treatment-refractory rate. Thus, there is a great need for novel treatment approaches. This article proposes a treatment approach centered on the concept of the gut–brain axis. There is mounting evidence indicating an association between stressors, microbiota, microglia, and mental disorders. Stressors might facilitate dysbiosis, inflammation, and the occurrence of mental disorders. This novel treatment approach is based on the idea that stressor types instead of the heterogeneous psychiatric diagnosis might be closer to the neurobiological underpinnings of mental disorders. First of all, patients with treatment-resistant mental disorders will be asked to describe their major stressors. Then, clinicians will calculate the total threat score and the total deprivation score. Subsequently, treatment tailored to the major stressor type will be administered to restore a healthy gut microbiome. Presumably, treatment will be aimed at increasing microbiota diversity in those who mainly have deprivation stressors and boosting Actinobacteria in those who have mainly threat stressors. Large-scale clinical trials are warranted to test this hypothetical approach.