Cannabinoid receptor-2 attenuates neuroinflammation by promoting autophagy-mediated degradation of the NLRP3 inflammasome post spinal cord injury

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“Background: Neuroinflammation following spinal cord injury (SCI) results in prolonged neurological damage and locomotor dysfunction. Polarization of microglia is vital to regulation of neuroinflammation, although the underlying mechanisms have not yet been elucidated. Endocannabinoid receptor subtype 2 (CB2R) is reported to ameliorate neurodegeneration via immunomodulation activities. However, the underlying machinery in the context of SCI remains unclear.

Methods: A lipopolysaccharide-induced microglia inflammation model and a mouse model of SCI were employed to investigate the regulatory role of CB2R in the polarization of microglia in response to excess neuroinflammation. Markers of inflammation and autophagy were measured by Western blot analysis, immunofluorescence, flow cytometry, and enzyme-linked immunosorbent assays. Histological staining with hematoxylin and eosin, Nissl, and Luxol® fast blue was conducted using commercial kits. The locomotor function of the hindlimbs of the experimental mice was evaluated with the Basso Mouse Scale, Louisville Swim Scale, and footprint assay.

Results: The results showed that CB2R promoted M2 differentiation, increased interleukin (IL)-10 expression, and inhibited M1 differentiation with decreased expression of IL-1β and IL-6. CB2R activation also increased ubiquitination of the NLRP3 inflammasome and interacted with the autophagy-related proteins p62 and microtubule-associated proteins 1B light chain 3. Treatment with the CB2R activator JWH-133 reduced loss of myelin, apoptosis of neurons, and glial scarring, leading to improved functional recovery of the hindlimbs, while the CB2R antagonist AM630 produced opposite results.

Conclusion: Taken together, these results suggested that CB2R activation attenuated neuroinflammation targeting microglial polarization by promoting NLRP3 clearance, thereby facilitating functional recovery post-SCI.”

https://pubmed.ncbi.nlm.nih.gov/36238284/

https://www.frontiersin.org/articles/10.3389/fimmu.2022.993168/full

Cannabidiol-loaded injectable chitosan-based hydrogels promote spinal cord injury repair by enhancing mitochondrial biogenesis

International Journal of Biological Macromolecules

“The treatment of traumatic spinal cord injury (SCI) remains challenging as the neuron regeneration is impaired by irregular cavity and apoptosis. An injectable in situ gelling hydrogel is therefore developed for the local delivery of cannabidiol (CBD) through a novel method based on polyelectrolyte (PEC) interaction of sodium carboxymethylcellulose (CMC) and chitosan (CS). It can be injected into the spinal cord cavity with a 26-gauge syringe before gelation, and gelled after 110 ± 10 s. Of note, the in-situ forming hydrogel has mechanical properties similar to spinal cord. Moreover, the CBD-loaded hydrogels sustain delivery of CBD for up to 72 h, resulting in reducing apoptosis in SCI by enhancing mitochondrial biogenesis. Importantly, the CBD-loaded hydrogels raise neurogenesis more than pure hydrogels both in vivo and in vitro, further achieving significant recovery of motor and urinary function in SCI rats. Thus, it suggested that CMC/CS/CBD hydrogels could be used as promising biomaterials for tissue engineering and SCI.”

https://pubmed.ncbi.nlm.nih.gov/36075309/

https://www.sciencedirect.com/science/article/abs/pii/S0141813022019353?via%3Dihub


Cannabidiol attenuates hypersensitivity and oxidative stress after traumatic spinal cord injury in rats

Neuroscience Letters

“Neuropathic pain (NP) arises as a direct consequence of traumatic spinal cord injury (SCI), which leads to devastating consequences for people suffering from this condition since no specific treatment has been defined. One relevant mechanism in generating painful stimuli involves the direct participation of reactive oxygen species (ROS) at the cellular and subcellular levels.

Cannabidiol (CBD) is one of the two most crucial cannabinoid components of the cannabis plant and has been proposed as a potential treatment for NP. Its antioxidant, neuroprotective and anti-inflammatory properties have been documented. However, there is insufficient evidence regarding CBD as treatment of NP induced by SCI or the mechanisms that underlie this effect.

In this study, we evaluated the antinociceptive effect of CBD as an acute treatment after the nociceptive behaviors characteristic of NP were established (hypersensitivity threshold and hypersensitivity response). Furthermore, the participation of oxidative stress was determined by lipid peroxidation (LP) and glutathione concentration (GSH) in female Wistar rats with SCI.

Acute treatment with CBD (2.5-20 mg/kg, i.p.) decreased nociceptive behaviors in a dose-dependent manner, decreased LP, and increased GSH concentration in injured tissue 15 days after injury. The findings of this study suggest that the antinociceptive effect induced by CBD is regulated by reducing oxidative stress by decreasing the LP and increasing the concentration of antioxidant (GSH) defenses.”

https://pubmed.ncbi.nlm.nih.gov/36028005/

“Cannabidiol decreases hyperalgesia in a dose–response manner after spinal cord injury.”

https://www.sciencedirect.com/science/article/abs/pii/S0304394022004165?via%3Dihub

Treatments perceived to be helpful for neuropathic pain after traumatic spinal cord injury: A multicenter cross-sectional survey study

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“Objective: To evaluate the perceived helpfulness of pharmacological and non-pharmacological interventions and their combinations for neuropathic pain (NeuP) and subcategories of NeuP after spinal cord injury (SCI).

Methods: Three hundred ninety one individuals at least one year post traumatic SCI were enrolled. A telephone survey was conducted to determine the pharmacologic and non-pharmacologic treatments used in the last 12 months for each participant’s three worst pains, whether these treatments were “helpful”, and if currently used, each treatments’ effectiveness.

Results: Two hundred twenty participants (56%) reported 354 distinct NeuPs. Pharmacological treatments rated helpful for NeuP were non-tramadol opioids (opioids were helpful for 86% of opioid treated NeuPs), cannabinoids (83%), and anti-epileptics (79%). Non-pharmacological treatments rated helpful for NeuP were massage (76%), body position adjustment (74%), and relaxation therapy (70%). Those who used both opioids and exercise reported greater NeuP treatment helpfulness compared to participants using opioids without exercise (P = 0.03).

Conclusions: Opioids, cannabinoids, and massage were reported more commonly as helpful than treatments recommended as first-line therapies by current clinical practice guidelines (CPGs) for NeuP after SCI (antiepileptics and antidepressants). Individuals with SCI likely value the modulating effects of pharmacological and non-pharmacological treatments on the affective components of pain in addition to the sensory components of pain when appraising treatment helpfulness.”

https://pubmed.ncbi.nlm.nih.gov/35993799/

https://www.tandfonline.com/doi/full/10.1080/10790268.2022.2108665?scroll=top&needAccess=true

Cannabidiol-treated rats exhibited higher motor score after cryogenic spinal cord injury

SpringerLink

“Cannabidiol (CBD), a non-psychoactive constituent of cannabis, has been reported to induce neuroprotective effects in several experimental models of brain injury. We aimed at investigating whether this drug could also improve locomotor recovery of rats submitted to spinal cord cryoinjury.

Rats were distributed into five experimental groups. Animals were submitted to laminectomy in vertebral segment T10 followed or not by application of liquid nitrogen for 5 s into the spinal cord at the same level to cause cryoinjury. The animals received injections of vehicle or CBD (20 mg/kg) immediately before, 3 h after and daily for 6 days after surgery. The Basso, Beattie, and Bresnahan motor evaluation test was used to assess motor function post-lesion one day before surgery and on the first, third, and seventh postoperative days. The extent of injury was evaluated by hematoxylin-eosin histology and FosB expression.

Cryogenic lesion of the spinal cord resulted in a significant motor deficit. Cannabidiol-treated rats exhibited a higher Basso, Beattie, and Bresnahan locomotor score at the end of the first week after spinal cord injury: lesion + vehicle, day 1: zero, day 7: four, and lesion + Cannabidiol 20 mg/kg, day 1: zero, day 7: seven. Moreover, at this moment there was a significant reduction in the extent of tissue injury and FosB expression in the ventral horn of the spinal cord.

The present study confirmed that application of liquid nitrogen to the spinal cord induces reproducible and quantifiable spinal cord injury associated with locomotor function impairments.

Cannabidiol improved locomotor functional recovery and reduced injury extent, suggesting that it could be useful in the treatment of spinal cord lesions.”

https://pubmed.ncbi.nlm.nih.gov/21915768/

https://link.springer.com/article/10.1007/s12640-011-9273-8

The Impact of Isolated Baseline Cannabis Use on Outcomes Following Thoracolumbar Spinal Fusion: A Propensity Score-Matched Analysis

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“Background: There is limited literature evaluating the impact of isolated cannabis use on outcomes for patients following spinal surgery. This study sought to compare 90-day complication, 90-day readmission, as well as 2-year revision rates between baseline cannabis users and non-users following thoracolumbar spinal fusion (TLF) for adult spinal deformity (ASD).

Results: 704 patients were identified (n=352 each), with comparable age, sex, race, primary insurance, Charlson/Deyo scores, surgical approach, and levels fused between cohorts (all, p>0.05). Cannabis users (versus non-users) incurred lower 90-day overall and medical complication rates (2.4% vs. 4.8%, p=0.013; 2.0% vs. 4.1%, p=0.018). Cohorts had otherwise comparable complication, revision, and readmission rates (p>0.05). Baseline cannabis use was associated with a lower risk of 90-day medical complications (OR=0.47, p=0.005). Isolated baseline cannabis use was not associated with 90-day surgical complications and readmissions, or two-year revisions.

Conclusion: Isolated baseline cannabis use, in the absence of any other diagnosed substance abuse disorders, was not associated with increased odds of 90-day surgical complications or readmissions or two-year revisions, though its use was associated with reduced odds of 90-day medical complications when compared to non-users undergoing TLF for ASD. Further investigations are warranted to identify the physiologic mechanisms underlying these findings. Level of Evidence: III.”

https://pubmed.ncbi.nlm.nih.gov/35821925/

“Compared to patients with ASD who underwent TLF without baseline cannabis use, patients with isolated baseline cannabis use were found to have no increase in odds of incurring 90-day surgical complications or readmissions or revisions two years postoperatively, though reduced odds of experiencing 90-day medical complications were observed.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9210439/

Promoting Oligodendrocyte Differentiation from Human Induced Pluripotent Stem Cells by Activating Endocannabinoid Signaling for Treating Spinal Cord Injury

SpringerLink

“Transplantation of oligodendrocyte progenitor cell (OPC) at the injury site is being developed as a potential therapeutic strategy for promoting remyelination and locomotor function recovery after spinal cord injury (SCI). To this end, the development of expandable and functional human OPCs is crucial for testing their efficacy in SCI.

In mice and rats, the endocannabinoid signaling system is crucial for the survival, differentiation, and maturation of OPCs. Similar studies in humans are lacking currently. Endocannabinoids and exogenous cannabinoids exert their effects mainly via cannabinoid receptors (CB1R and CB2R). We demonstrated that these receptors were differentially expressed in iPSC-derived human NSCs and OPCs, and they could be activated by WIN55212-2 (WIN), a potent CB1R/CB2R agonist to upregulate the endocannabinoid signaling during glial induction.

WIN primed NSCs generated more OLIG2 + glial progenitors and migratory PDGFRα + OPC in a CB1/CB2 dependent manner compared to unprimed NSCs. Furthermore, WIN-induced OPCs (WIN-OPCs) robustly differentiated into functional oligodendrocytes and myelinate in vitro and in vivo in a mouse spinal cord injury model. RNA-Seq revealed that WIN upregulated the biological process of positive regulation of oligodendrocyte differentiation. Mechanistically, WIN could act as a partial smoothed (SMO) inhibitor or activate CB1/CB2 to form heteromeric complexes with SMO leading to the inhibition of GLI1 in the Sonic hedgehog pathway.

The partial and temporal inhibition of GLI1 during glial induction is shown to promote OPCs that differentiate faster than control’s. Thus, CB1R/CB2R activation results in more efficient generation of OPCs that can mature and efficiently myelinate.”

https://pubmed.ncbi.nlm.nih.gov/35725998/

https://link.springer.com/article/10.1007/s12015-022-10405-0


Will Cannabigerol Trigger Neuroregeneration after a Spinal Cord Injury? An In Vitro Answer from NSC-34 Scratch-Injured Cells Transcriptome

“Spinal cord injury affects the lives of millions of people around the world, often causing disability and, in unfortunate circumstances, death. Rehabilitation can partly improve outcomes and only a small percentage of patients, typically the least injured, can hope to return to normal living conditions. Cannabis sativa is gaining more and more interest in recent years, even though its beneficial properties have been known for thousands of years. Cannabigerol (CBG), extracted from C. sativa, is defined as the “mother of all cannabinoids” and its properties range from anti-inflammatory to antioxidant and neuroprotection. Using NSC-34 cells to model spinal cord injury in vitro, our work evaluated the properties of CBG treatments in motor neuron regeneration. While pre-treatment can modulate oxidative stress and increase antioxidant enzyme genes, such as Tnx1, decreasing Nos1 post-treatment seems to induce regeneration genes by triggering different pathways, such as Gap43 via p53 acetylation by Ep300 and Ddit3 and Xbp1 via Bdnf signaling, along with cytoskeletal remodeling signaling genes Nrp1 and Map1b. Our results indicate CBG as a phytocompound worth further investigation in the field of neuronal regeneration.”

https://pubmed.ncbi.nlm.nih.gov/35215230/

Analyzing the Impact of Cannabinoids on the Treatment of Spinal Disorders

“Purpose of review: Cannabis is among the most used illicit substances globally, with medical applications, increased legalization, and shifting social attitudes leading to increased use in recent years. Cannabinoids are a group of psychoactive substances found within the cannabis plant, with the most common being Δ9-tetrahydrocannabinol and cannabidiol. Due to the high prevalence of use, it is increasingly important to evaluate the effects of cannabis and cannabinoids on spine patients, in both operative and nonoperative settings.

Recent findings: Cannabis and cannabinoids may be effective in treating patients with chronic conditions such as back pain and spinal cord injuries. Longitudinal effects and implications on surgical outcomes and complications are poorly understood. High-quality, outcomes-focused research can inform approaches for clinicians to approach cannabis and cannabinoid use. Studies to elucidate the standardization of cannabis regimens can help develop guidelines for potential therapeutic applications. Cannabis and cannabinoids may be useful alternatives or additions for many spine patients, but future research is needed for recommendations to be determined. Our manuscript reviews the available literature regarding cannabis use and various spinal conditions, organizing our findings into the following narrative themes: (1) the management of chronic lower back pain, (2) perioperative outcomes, (3) cannabis use in general orthopaedic procedures, and (4) spinal cord injuries.”

https://pubmed.ncbi.nlm.nih.gov/35132567/

Systematic review of the impact of cannabinoids on neurobehavioral outcomes in preclinical models of traumatic and nontraumatic spinal cord injury

Spinal Cord“Objectives: To evaluate the impact of cannabinoids on neurobehavioral outcomes in preclinical models of nontraumatic and traumatic spinal cord injury (SCI), with the aim of determining suitability for clinical trials involving SCI patients.

Results: The search returned 8714 studies, 19 of which met our inclusion criteria. Sample sizes ranged from 23 to 390 animals. WIN 55,212-2 (n = 6) and AM 630 (n = 8) were the most used cannabinoid receptor agonist and antagonist respectively. Acute SCI models included traumatic injury (n = 16), ischaemia/reperfusion injury (n = 2), spinal cord cryoinjury (n = 1) and spinal cord ischaemia (n = 1). Assessment tools used assessed locomotor function, pain and anxiety. Cannabinoid receptor agonists resulted in statistically significant improvement in locomotor function in 9 out of 10 studies and pain outcomes in 6 out of 6 studies.

Conclusion: Modulation of the endo-cannabinoid system has demonstrated significant improvement in both pain and locomotor function in pre-clinical SCI models; however, the risk of bias is unclear in all studies. These results may help to contextualise future translational clinical trials investigating whether cannabinoids can improve pain and locomotor function in SCI patients.”

https://pubmed.ncbi.nlm.nih.gov/34392312/

“The results of these studies demonstrate that modulation of the endo-cannabinoid system has significant benefit for both pain and locomotor function across a range of pre-clinical models of acute spinal cord injury.”

https://www.nature.com/articles/s41393-021-00680-y