Preclinical Literature Research Articles

“Neuroinflammation”: does it have a role in chronic pain? Evidence from human imaging

Abstract Despite hundreds of studies demonstrating the involvement of neuron-glia-immune interactions in the establishment and/or maintenance of persistent pain behaviors in animals, the role (or even occurrence) of so-called “neuroinflammation” in human pain has been an object of contention for decades. Here, I present the results of multiple positron emission tomography (PET) studies measuring the levels of the 18 kDa translocator protein (TSPO), a putative neuroimmune marker, in individuals with various pain conditions. Overall, these studies suggest that brain TSPO PET signal: (1) is elevated, compared to healthy volunteers, in individuals with chronic low back pain (with additional elevations in spinal cord and neuroforamina), fibromyalgia, migraine and other conditions characterized by persistent pain; (2) has a spatial distribution exhibiting a degree of disorder specificity; (3) is parametrically linked to pain characteristics or comorbid symptoms (eg, nociplastic pain, fatigue, depression), as well as measures of brain function (ie, functional connectivity), in a regionally-specific manner. In this narrative, I also discuss important caveats to consider in the interpretation of this work (eg, regarding the cellular source of the signal and the complexities inherent in its acquisition and analysis). While the biological and clinical significance of these findings awaits further work, this emerging preclinical literature supports a role of neuron-glia-immune interactions as possible pathophysiological underpinnings of human chronic pain. Gaining a deeper understanding of the role of neuroimmune function in human pain would likely have important practical implications, possibly paving the way for novel interventions.

Sex differences in glutamate transmission and plasticity in reward related regions.

Disruptions in glutamate homeostasis within the mesolimbic reward circuitry may play a role in the pathophysiology of various reward related disorders such as major depressive disorders, anxiety, and substance use disorders. Clear sex differences have emerged in the rates and symptom severity of these disorders which may result from differing underlying mechanisms of glutamatergic signaling. Indeed, preclinical models have begun to uncover baseline sex differences throughout the brain in glutamate transmission and synaptic plasticity. Glutamatergic synaptic strength can be assessed by looking at morphological features of glutamatergic neurons including spine size, spine density, and dendritic branching. Likewise, electrophysiology studies evaluate properties of glutamatergic neurons to provide information of their functional capacity. In combination with measures of glutamatergic transmission, synaptic plasticity can be evaluated using protocols that induce long-term potentiation or long-term depression. This review will consider preclinical rodent literature directly comparing glutamatergic transmission and plasticity in reward related regions of males and females. Additionally, we will suggest which regions are exhibiting evidence for sexually dimorphic mechanisms, convergent mechanisms, or no sex differences in glutamatergic transmission and plasticity and highlight gaps in the literature for future investigation.

Microbiome contributions to pain: a review of the preclinical literature.

Over the past 2 decades, the microbiome has received increasing attention for the role that it plays in health and disease. Historically, the gut microbiome was of particular interest to pain scientists studying nociplastic visceral pain conditions given the anatomical juxtaposition of these microorganisms and the neuroimmune networks that drive pain in such diseases. More recently, microbiomes both inside and across the surface of the body have been recognized for driving sensory symptoms in a broader set of diseases. Microbiomes have never been a more popular topic in pain research, but to date, there has not been a systematic review of the preclinical microbiome pain literature. In this article, we identified all animal studies in which both the microbiome was manipulated and pain behaviors were measured. Our analysis included 303 unique experiments across 97 articles. Microbiome manipulation methods and behavioral outcomes were recorded for each experiment so that field-wide trends could be quantified and reported. This review specifically details the animal species, injury models, behavior measures, and microbiome manipulations used in preclinical pain research. From this analysis, we were also able to conclude how manipulations of the microbiome alter pain thresholds in naïve animals and persistent pain intensity and duration in cutaneous and visceral pain models. This review summarizes by identifying existing gaps in the literature and providing recommendations for how to best plan, implement, and interpret data collected in preclinical microbiome pain experiments.

Resveratrol delays the progression of diabetic nephropathy through multiple pathways: A dose-response meta-analysis based on animal models.

Accumulating experimental evidence has shown that resveratrol supplementation is effective for treating diabetic nephropathy (DN) in animal models. In this systematic review and meta-analysis, we assessed the effects and multiple mechanisms of resveratrol in animal models of DN. Before September 2023, preclinical literature was systematically searched and screened across PubMed, Web of Science, EMBASE, and the Cochrane Library. Forty-two studies were included, and the risk of bias tool from SYRCLE was used to assess the methodological quality. Pooled overall effect sizes of the results were generated by STATA 16.0. The overall results provide preliminary evidence that the consumption of resveratrol can significantly reduce the mesangial index, glomerular basement membrane thickness, glomerular hypertrophy, serum creatinine, blood urea nitrogen, 24-h urinary protein, blood glucose, kidney index, total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels. In contrast, the levels of albumin and high-density lipoprotein cholesterol are significantly increased. However, resveratrol did not significantly reduce creatinine clearance or glycated hemoglobin levels. Dose-response analysis revealed that resveratrol was most effective at improving kidney function and reducing DN when administered at lower doses of ≤15 mg/kg/day or higher doses of 100-200 mg/kg/day, with significant improvements in biochemical kidney injury markers and a better effect on dysglycemia. The benefits of resveratrol in DN are likely due to its anti-inflammatory, antioxidant, metabolic regulatory, and autophagy-promoting effects. To confirm these findings for clinical use, further large-scale, long-term, high-quality preclinical trials are warranted to accurately assess the anti-DN effects and safety of resveratrol.

Revisiting dezocine for opioid use disorder: A narrative review of its potential abuse liability.

Opioid use disorder (OUD) remains a serious public health problem. Opioid maintenance treatment is effective but under-utilized, hard to access under existing federal regulations, and, once patients achieve OUD stability, challenging to discontinue. Fewer than 2% of persons with OUD stop using opioids completely. There have been calls from public advocacy groups, governmental agencies, and public health officials for new treatments for OUD. Dezocine, a non-scheduled opioid previously used in the United States and currently widely prescribed in China for pain management, could be a candidate for a novel OUD treatment medication in the U.S. Nonetheless, to date, there have been no reviews of the clinical and preclinical literature detailing dezocine's abuse potential, a key consideration in assessing its clinical utility. There are no English language reports of human abuse, dependence, or overdose of dezocine, despite years of extensive clinical use. There are a few case reports of dezocine abuse in the Chinese literature, but there are no reports of overdose deaths. Dezocine is perceived as an opioid and is "liked" by opioid-experienced human and non-human primates, properties that are not dose-dependent and are mitigated by ceiling effects-higher doses do not result in more "liking." There is little withdrawal, spontaneous or precipitated, in humans, monkeys, rats, or mice treated chronically with dezocine alone. However, at some doses, dezocine can precipitate withdrawal in humans and monkeys dependent on other opioids. In rodents, dezocine reduces the severity of morphine withdrawal and the rewarding properties of other opioids. Although dezocine is reinforcing in humans and monkeys with prior or concurrent opioid use within a restricted dose range, there are only a few anecdotal reports of dezocine abuse despite of the long history of use in humans. Given the evidence of dezocine's limited abuse potential, it could be useful both as a treatment for OUD. However, in-depth studies would be required for dezocine to be re-considered for clinical use.

Anxiety and risk-taking behavior maps onto opioid and alcohol polysubstance consumption patterns in male and female mice.

Polysubstance use is prevalent in the population but remains understudied in preclinical models. Alcohol and opioid polysubstance use is associated with negative outcomes, worse treatment prognosis, and higher overdose risk; but underlying mechanisms are still being uncovered. Examining factors that motivate use of one substance over another in different contexts in preclinical models will better our understanding of polysubstance use and improve translational value. Here we assessed baseline anxiety-like and locomotive behavior and then measured voluntary consumption of multiple doses of alcohol and fentanyl in group housed male and female mice using our novel Socially Integrated Polysubstance (SIP) system. Fifty-six male (n=32) and female (n=24) adult mice were housed in groups of 4 for one week with continuous access to food, water, two doses of ethanol (5% and 10%) and two doses of fentanyl (5 ug/ml and 20 ug/ml). Our analyses revealed sex differences across multiple domains - female mice consumed more liquid in the dark cycle, had higher activity, a higher preference for both ethanol and fentanyl over water, and their fentanyl preference increased over the seven days. We then used machine-learning techniques to reveal underlying relationships between baseline behavioral phenotypes and subsequent polysubstance consumption patterns, where anxiety-and risk-taking-like behavioral phenotypes mapped onto discrete patterns of polysubstance use, preference, and escalation. By simulating more translationally relevant substance use and improving our understanding of the motivations for different patterns of consumption, this study contributes to the developing preclinical literature on polysubstance use with the goal of facilitating better treatment outcomes and novel therapeutic strategies.

Autism, youth suicide, and psychedelics: A review of the 21st century evidence.

The concurrent rise in the prevalence of autism and youth suicide has drawn public health and professional attention. The renaissance of psychedelics in psychiatry occurred in the early 21st century and may suggest a hope for the therapeutic effect of psychedelics in autism and suicide. The psychedelics' molecular entities are the compounds that modulate the serotoninergic and glutamatergic systems, which play a crucial role in the pathomechanisms underlying autism and suicide. This systematic review comprehensively discussed the prevalence trends of autism and youth suicide globally and in Taiwan and discussed an association between autism and suicidality based on the 21st century clinical and preclinical literature. Furthermore, this review proposed a possible neurobiological connection between autism, suicide, and psychedelics. Finally, this review discussed the potential therapeutic applications of psychedelics in autism and youth suicide.

Neurological Disorders Induced by Drug Use: Effects of Adolescent and Embryonic Drug Exposure on Behavioral Neurodevelopment.

Clinical studies demonstrate that the risk of developing neurological disorders is increased by overconsumption of the commonly used drugs, alcohol, nicotine and cannabis. These drug-induced neurological disorders, which include substance use disorder (SUD) and its co-occurring emotional conditions such as anxiety and depression, are observed not only in adults but also with drug use during adolescence and after prenatal exposure to these drugs, and they are accompanied by long-lasting disturbances in brain development. This report provides overviews of clinical and preclinical studies, which confirm these adverse effects in adolescents and the offspring prenatally exposed to the drugs and include a more in-depth description of specific neuronal systems, their neurocircuitry and molecular mechanisms, affected by drug exposure and of specific techniques used to determine if these effects in the brain are causally related to the behavioral disturbances. With analysis of further studies, this review then addresses four specific questions that are important for fully understanding the impact that drug use in young individuals can have on future pregnancies and their offspring. Evidence demonstrates that the adverse effects on their brain and behavior can occur: (1) at low doses with short periods of drug exposure during pregnancy; (2) after pre-conception drug use by both females and males; (3) in subsequent generations following the initial drug exposure; and (4) in a sex-dependent manner, with drug use producing a greater risk in females than males of developing SUDs with emotional conditions and female offspring after prenatal drug exposure responding more adversely than male offspring. With the recent rise in drug use by adolescents and pregnant women that has occurred in association with the legalization of cannabis and increased availability of vaping tools, these conclusions from the clinical and preclinical literature are particularly alarming and underscore the urgent need to educate young women and men about the possible harmful effects of early drug use and to seek novel therapeutic strategies that might help to limit drug use in young individuals.

Sex Differences in Mouse Models of Voluntary Alcohol Drinking and Abstinence-Induced Negative Emotion

Alcohol Use Disorder (AUD) is a growing problem worldwide, causing an incredible burden on health and the economy. Though AUD impacts people of all backgrounds and demographics, increasing evidence has suggested robust sex differences in alcohol drinking patterns and AUD-induced negative emotionality or hyperkatifeia. Rates of problematic drinking have significantly risen among women, and women face more severe negative emotional consequences in abstinence such as increased risk of comorbidity with an anxiety or mood disorder and more severe symptoms of depression. As such, a bevy of preclinical literature using contingent methods of alcohol (ethanol) consumption has amassed in recent years to better understand sex as a biological variable in alcohol drinking and abstinence-induced negative emotionality. Mice are widely used to model alcohol drinking, as they are conducive to genetic manipulation strategies, and many strains will voluntarily consume alcohol. Sex-specific results from these mouse studies, however, have been inconsistent. Therefore, this review aims to summarize the current knowledge on sex differences in AUD-related contingent ethanol drinking and abstinence-induced negative emotionality in mice. Various contingent mouse drinking models and negative emotional-based behavioral paradigms are introduced and subsequently discussed in the context of sex differences to show increasing indications of sex specificity in mouse preclinical studies of AUD. With this review, we hope to inform future research on potential sex differences in preclinical mouse models of AUD and provide mounting evidence supporting the need for more widespread inclusion of preclinical female subjects in future studies.

Intra-articular corticosteroids for the treatment of osteoarthritis: A systematic review and meta-analysis on the comparison of different molecules and doses.

The purpose of this study was to quantify and compare the clinical relevance of the different intra-articular corticosteroids (CS) effects in vivo for osteoarthritis (OA) treatment. The search was conducted on PubMed, Cochrane,and Web of Science in October 2023. The PRISMA guidelines were used. Inclusion criteria: animal or human randomized controlled trials (RCTs), English language andno time limitation, on the comparison of different intra-articular CS for OA treatment. The articles' quality was assessed using the Cochrane RoB2 and GRADE guidelines for human RCTs, and SYRCLE's tool for animal RCTs. Eighteen RCTs were selected (16 human and 2 animal studies), including 1577 patients (1837 joints) and 31 animals (51 joints). The CS used were triamcinolone (14 humanand 2 animal studies), methylprednisolone (7 humanand 1 animal study), betamethasone (3 human studies)and dexamethasone (1 human study). All studies addressed knee OA except for three human and one animal study. A meta-analysis was performed on the comparison of methylprednisolone and triamcinolone in humans with knee OA analysing VAS pain at very short- (≤2 weeks), short- (>2and ≤4 weeks), mid- (>4and ≤8 weeks), long- (>8and ≤ 12 weeks),and very long-term (>12and ≤24 weeks). Triamcinolone showed better post-injection values compared to methylprednisolone at very short-term (p = 0.028). No difference in terms of VAS improvement was observed at any follow-up. The available preclinical and clinical literature provides limited evidence on the comparison of different CS, hindering the possibility of determining the best CS approach in terms of molecule and dose for the intra-articular injection of OA joints. Level I.

A systematic review of normal tissue neurovascular unit damage following brain irradiation-Factors affecting damage severity and timing of effects.

Radiotherapy is key in the treatment of primary and secondary brain tumors. However, normal tissue is inevitably irradiated, causing toxicity and contributing to cognitive dysfunction. The relative importance of vascular damage to cognitive decline is poorly understood. Here, we systematically review the evidence for radiation-induced damage to the entire neurovascular unit (NVU), particularly focusing on establishing the factors that influence damage severity, and timing and duration of vascular effects relative to effects on neural tissue. Using PubMed and Web of Science, we searched preclinical and clinical literature published between January 1, 1970 and December 1, 2022 and evaluated factors influencing NVU damage severity and timing of NVU effects resulting from ionizing radiation. Seventy-two rodents, 4 canines, 1 rabbit, and 5 human studies met inclusion criteria. Radiation increased blood-brain barrier (BBB) permeability, reduced endothelial cell number and extracellular matrix proteoglycans, reduced tight junction proteins, upregulated cellular adhesion molecule expression, reduced activity of glucose and BBB efflux transporters and activated glial cells. In the brain parenchyma, increased metalloproteinases 2 and 9 levels, demyelination, cell death, and inhibited differentiation were observed. Effects on the vasculature and neural compartment were observed across acute, delayed, and late timepoints, and damage extent was higher with low linear energy transfer radiation, higher doses, lower dose rates, broader beams, and in the presence of a tumor. Irradiation of normal brain tissue leads to widespread and varied impacts on the NVU. Data indicate that vascular damage is in most cases an early effect that does not quickly resolve. More studies are needed to confirm sequence of damages, and mechanisms that lead to cognitive dysfunction.

A scoping review of the effects of mushroom and fungus extracts in rodent models of depression and tests of antidepressant activity.

One of the most important developments in psychopharmacology in the past decade has been the emergence of novel treatments for mood disorders, such as psilocybin for treatment-resistant depression. Psilocybin is most commonly found in different species of mushroom; however, the literature on mushroom and fungus extracts with potential antidepressant activity extends well beyond just psilocybin-containing mushrooms, and includes both psychedelic and non-psychedelic species. In the current review, we systematically review the preclinical literature on mushroom and fungus extracts, and their effects of animal models of depression and tests of antidepressant activity. The PICO structure, PRISMA checklist and the Cochrane Handbook for systematic reviews of intervention were used to guide the search strategy. A scoping search was conducted in electronic databases PubMed, CINAHL, Embase and Web of Science. The literature search identified 50 relevant and suitable published studies. These included 19 different species of mushrooms, as well as seven different species of other fungi. Nearly all studies reported antidepressant-like effects of treatment with extracts. Treatments were most commonly delivered orally, in both acute and chronically administered studies to predominantly male rodents. Multiple animal models of depression were used, the most common being unpredictable chronic mild stress, while the tail suspension test and forced swim test were most frequently used as standalone antidepressant screens. Details on each experiment with mushroom and fungus species are discussed in detail, while an evaluation is provided of the strengths and weaknesses of these studies.

Thyroid hormone analogues: Promising therapeutic avenues to improve the neurodevelopmental outcomes of intrauterine growth restriction.

Intrauterine growth restriction (IUGR) is a pregnancy complication impairing fetal growth and development. The compromised development is often attributed to disruptions of oxygen and nutrient supply from the placenta, resulting in a number of unfavourable physiological outcomes with impaired brain and organ growth. IUGR is associated with compromised development of both grey and white matter, predisposing the infant to adverse neurodevelopmental outcomes, including long-lasting cognitive and motor difficulties. Cerebral thyroid hormone (TH) signalling, which plays a crucial role in regulating white and grey matter development, is dysregulated in IUGR, potentially contributing to the neurodevelopmental delays associated with this condition. Notably, one of the major TH transporters, monocarboxylate transporter-8 (MCT8), is deficient in the fetal IUGR brain. Currently, no effective treatment to prevent or reverse IUGR exists. Management strategies involve close antenatal monitoring, management of maternal risk factors if present and early delivery if IUGR is found to be severe or worsening in utero. The overall goal is to determine the most appropriate time for delivery, balancing the risks of preterm birth with further fetal compromise due to IUGR. Drug candidates have shown either adverse effects or little to no benefits in this vulnerable population, urging further preclinical and clinical investigation to establish effective therapies. In this review, we discuss the major neuropathology of IUGR driven by uteroplacental insufficiency and the concomitant long-term neurobehavioural impairments in individuals born IUGR. Importantly, we review the existing clinical and preclinical literature on cerebral TH signalling deficits, particularly the impaired expression of MCT8 and their correlation with IUGR. Lastly, we discuss the current evidence on MCT8-independent TH analogues which mimic the brain actions of THs by being metabolised in a similar manner as promising, albeit underappreciated approaches to promote grey and white matter development and improve the neurobehavioural outcomes following IUGR.

Preclinical Milestones in MECP2 Gene Transfer for Treating Rett Syndrome.

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2). After gene transfer in mice, exogenous MeCP2 expression must be regulated to avoid dose-dependent toxicity. The preclinical gene therapy literature for treating RTT illustrates a duly diligent progression that begins with proof-of-concept studies and advances toward the development of safer, regulated MECP2 viral genome designs. This design progression was partly achieved through international collaborative studies. In 2023, clinicians administered investigational gene therapies for RTT to patients a decade after the first preclinical gene therapy publications for RTT (clinical trial numbers NCT05606614 and NCT05898620). As clinicians take on a more prominent role in MECP2 gene therapy research, preclinical researchers may continue to test more nuanced hypotheses regarding the safety, efficacy, and mechanism of MECP2 gene transfer. This review summarizes the history of preclinical MECP2 gene transfer for treating RTT and acknowledges major contributions among colleagues in the field. The first clinical injections are a shared milestone.

Effect-Size Discrepancies in Literature Versus Raw Datasets from Experimental Spinal Cord Injury Studies: A CLIMBER Meta-Analysis.

Translation of spinal cord injury (SCI) therapeutics from pre-clinical animal studies into human studies is challenged by effect size variability, irreproducibility, and misalignment of evidence used by pre-clinical versus clinical literature. Clinical literature values reproducibility, with the highest grade evidence (class 1) consisting of meta-analysis demonstrating large therapeutic efficacy replicating across multiple studies. Conversely, pre-clinical literature values novelty over replication and lacks rigorous meta-analyses to assess reproducibility of effect sizes across multiple articles. Here, we applied modified clinical meta-analysis methods to pre-clinical studies, comparing effect sizes extracted from published literature to raw data on individual animals from these same studies. Literature-extracted data (LED) from numerical and graphical outcomes reported in publications were compared with individual animal data (IAD) deposited in a federally supported repository of SCI data. The animal groups from the IAD were matched with the same cohorts in the LED for a direct comparison. We applied random-effects meta-analysis to evaluate predictors of neuroconversion in LED versus IAD. We included publications with common injury models (contusive injuries) and standardized end-points (open field assessments). The extraction of data from 25 published articles yielded n = 1841 subjects, whereas IAD from these same articles included n = 2441 subjects. We observed differences in the number of experimental groups and animals per group, insufficient reporting of dropout animals, and missing information on experimental details. Meta-analysis revealed differences in effect sizes across LED versus IAD stratifications, for instance, severe injuries had the largest effect size in LED (standardized mean difference [SMD = 4.92]), but mild injuries had the largest effect size in IAD (SMD = 6.06). Publications with smaller sample sizes yielded larger effect sizes, while studies with larger sample sizes had smaller effects. The results demonstrate the feasibility of combining IAD analysis with traditional LED meta-analysis to assess effect size reproducibility in SCI.

Advances in Tumor Management: Harnessing the Potential of Histotripsy.

Tissue ablation techniques have long been used in clinical settings to treat various oncologic diseases. However, many of these techniques are invasive and can cause substantial adverse effects. Histotripsy is a noninvasive, nonionizing, nonthermal tissue ablation technique that has the potential to replace surgical interventions in various clinical settings. Histotripsy works by delivering high-intensity focused ultrasound waves to target tissue. These waves create cavitation bubbles within tissues that rapidly expand and collapse, thereby mechanically fractionating the tissue into acellular debris that is subsequently absorbed by the body's immune system. Preclinical and clinical studies have demonstrated the efficacy of histotripsy in treating a range of diseases, including liver, pancreatic, renal, and prostate tumors. Safety outcomes of histotripsy have been generally favorable, with minimal adverse effects reported. However, further studies are needed to optimize the technique and understand its long-term effects. This review aims to discuss the importance of histotripsy as a noninvasive tissue ablation technique, the preclinical and clinical literature on histotripsy and its safety, and the potential applications of histotripsy in clinical practice. Keywords: Tumor Microenvironment, Ultrasound-High-Intensity Focused (HIFU), Ablation Techniques, Abdomen/GI, Genital/Reproductive, Nonthermal Tissue Ablation, Histotripsy, Clinical Trials, Preclinical Applications, Focused Ultrasound © RSNA, 2024.

The effect of early mobilisation (< 14 days) on pathophysiological and functional outcomes in animals with induced spinal cord injury: a systematic review with meta-analysis

IntroductionThe optimum time to mobilise (standing, walking) following spinal cord injury (SCI) is unknown but may have implications for patient outcomes. There are no high-quality experimental studies that examine this issue, with a paucity of guidance for clinicians. Pre-clinical studies lead research in this field and can contribute to knowledge and support future clinical practice. Objective: to evaluate the effect of early compared to no mobilisation on pathophysiological and functional outcomes in animals with induced SCI.MethodsA systematic review with meta-analysis was conducted by searching pre-clinical literature in MEDLINE (PubMed), Embase (Ovid), Web of Science, OpenGrey, and EThOS (June 2023). Studies were included of any research method giving numerical results comparing pathophysiological and functional outcomes in rats and mice mobilised within 14-days of induced SCI to those that did not mobilise. Data were synthesised using random-effects meta-analyses. The quality of the evidence was assessed using the CAMARADES checklist. The certainty of findings was reported using the GRADE approach. This study is registered on PROSPERO (CRD42023437494).ResultsSeventeen studies met the inclusion criteria. Outcomes found that Brain Derived Neurotrophic Factor levels were greater in those that initiated mobilisation within 14-days of SCI compared to the groups that did not. Mobilisation initiated within 14-days of SCI was also associated with statistically significant functional gains: (Basso, Beattie and Bresnahan locomotor rating score (BBB) = 2.13(0–21), CI 1.43, 2.84, Ladder Rung Walking Task = − 12.38(0–100), CI 20.01, − 4.76). Meta-analysis identified the greatest functional gains when mobilisation was initiated within 3 days of SCI (BBB = 3.00, CI 2.31–3.69, p < 0.001), or when delivered at low intensity (BBB = 2.88, CI 2.03–3.70, p < 0.001). Confidence in the findings from this review was low to moderate due to the risk of bias and mixed methodological quality.ConclusionMobilisation instigated within 14-days of injury, may be an effective way of improving functional outcomes in animal models following SCI, with delays potentially detrimental to recovery. Outcomes from this study support further research in this field to guide future clinical practice.

Abstract 279: Iatrogenic immunosuppression emplaces tacrolimus to drive squamous skin cancer progression and influence the microenvironment

Abstract One in thirteen organ transplant recipients (OTRs) develop post-transplant cutaneous squamous cell carcinoma (cSCC), leading to significant morbidity upon disease progression. Although chronic ultraviolet (UV) exposure primarily underlies keratinocyte carcinogenesis, long-term immunosuppression is a critical etiologic risk factor due to reduced systemic surveillance of dysplasia. Calcineurin inhibitors such as tacrolimus are commonly administered to suppress the immune system by blocking T-cell proliferation and preventing donor organ rejection. Contrarily, studies have evinced the off-target effects of immunosuppressives, namely azathioprine and cyclosporine, but not tacrolimus — the most widely used in all immunosuppression. In addition, the preclinical research literature has overlooked the contribution of stromal fibroblasts in the cSCC tumor microenvironment (TME). Hence, we hypothesize that tacrolimus exerts direct carcinogenic effects on keratinocytes and fibroblasts in the skin. We further postulate that tacrolimus enables a tumor-permissive microenvironment by activating dermal fibroblasts to cause aggressive and invasive keratinocyte carcinoma in OTRs. To examine this cellular crosstalk phenomenon, we used human keratinocytes, primary dermal fibroblasts and cSCC cells in mono- and co-cultures to mimic cutaneous and tumor complexities. Next, we assessed the molecular mechanisms utilized by tacrolimus to potentiate tumorigenesis pertinent to cell survival, proliferation and invasion. Herein, we show that tacrolimus promotes cell survival dose-dependently in cSCC cells. We also found that a fibroblast-cSCC spheroid co-culture significantly enhances cell invasion. In a wound-healing migration assay, tacrolimus increased the migratory capacity of normal keratinocytes and cSCC cells. However, cell proliferation remains nebulous due to cyclical dose-response effects in vitro. We then queried whether cell proliferation is affected in vivo using immunodeficient mice, and similar results were observed. We confirmed via immunoblotting that tacrolimus induced elevated expression of proliferation markers at distinct drug concentrations. Altogether, our findings illuminate keratinocyte-stroma interactions and particularly isolate the contributory role of tacrolimus in non-immune mediated cSCC pathogenesis. This knowledge suggests newer immunosuppressives that do not inhibit calcineurin activity may help relieve cutaneous malignancies in transplant recipients. Citation Format: Edwin Kumah, Yash Chhabra, Vania Wang, Agrani Dixit, Ashani Weeraratna, Kristin Bibee. Iatrogenic immunosuppression emplaces tacrolimus to drive squamous skin cancer progression and influence the microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 279.

Histamine-3 Receptor Availability and Glutamate Levels in the Brain: A PET-1H-MRS Study of Patients With Schizophrenia and Healthy Controls.

The histamine-3 receptor (H3R) may have a role in cognitive processes through its action as a presynaptic heteroreceptor inhibiting the release of glutamate in the brain. To explore this, we examined anterior cingulate cortex (ACC) and striatum H3R availability in patients with schizophrenia and characterized their relationships with glutamate levels in corresponding brain regions. We employed a cross-sectional study, recruiting 12 patients with schizophrenia and 12 healthy volunteers. Participants underwent positron emission tomography using the H3R-specific radio ligand [11C]MK-8278, followed by proton magnetic resonance spectroscopy to measure glutamate levels, recorded as Glu and Glx. Based on existing literature, the ACC and striatum were selected as regions of interest. We found significant inverse relationships between tracer uptake and Glu (r = -0.66, P = .02) and Glx (r = -0.62, P = .04) levels in the ACC of patients, which were absent in healthy volunteers (Glu: r = -0.19, P = .56, Glx: r = 0.10, P = .75). We also found a significant difference in striatal (F1,20 = 6.00, P = .02) and ACC (F1,19 = 4.75, P = .04) Glx levels between groups. These results provide evidence of a regionally specific relationship between H3Rs and glutamate levels, which builds on existing preclinical literature. Our findings add to a growing literature indicating H3Rs may be a promising treatment target in schizophrenia, particularly for cognitive impairment, which has been associated with altered glutamate signaling.

The Impact of Omega-3 on Improving Sleep Quality: A Systematic Review of Current Clinical Research

Introduction: Omega-3 fatty acids are known to improve cardiovascular and metabolic outcomes. While studies have suggested that omega-3 may also enhance sleep quality and regulate melatonin, the data on its efficacy for individuals with poor sleep quality or related disorders must be more consistent. We aim to pave the way for future investigations, ultimately contributing to the clinical management of sleep health. Methods: 87 articles were retrieved from MEDLINE and Cochrane databases through a systematic search strategy, and 19 articles from 2002 to 2022 were included. Inclusion criteria encompassed randomized controlled trials (RCTs) and observational studies focused on the impact omega-3 on outcomes related to sleep clinical parameters. Exclusion criteria included preclinical studies and literature reviews. Results: The review identified 19 eligible studies, consisting of 9 RCTs and ten observational studies. The results displayed a complex relationship between omega-3 supplementation and sleep quality, with some studies suggesting positive effects, particularly in specific subpopulations. In contrast, others showed no significant impact or even negative effects on sleep. Among the RCTs, 7 showed positive and promising results in favor of omega-3 supplementation for sleep quality, while 1 RCT indicated the need for further studies, and 1 RCT suggested no benefit of omega-3 on sleep quality. Among observational studies, 7 reported positive and promising outcomes with omega-3 supplementation, 2 indicated no benefit in improving sleep quality, and 1 suggested further studies. Conclusion: Based on the available data, our systematic review found that omega-3 improved sleep quality in 74% of the included clinical research; however, such evidence still needs to be conclusive due to high heterogeneity among study designs. Therefore, well-designed clinical studies are required to confirm this conclusion.