Mechanistic Insight into the Effects of Curcumin on Neuroinflammation-Driven Chronic Pain

Impact of curcumin supplementation on exercise performance and muscle damage after a soccer match: a double-blind placebo-controlled cross-over study

PURPOSE

Curcumin ingestion can mitigate muscle damage, soreness, and inflammation following a laboratory-based eccentric exercise. Similar effects were observed in recent field-based studies wherein responses were evaluated after a soccer match. However, various potential confounding factors, such as matching opponent skill levels and daily training conditions, may have influenced the outcomes. In the present study, we investigated whether curcumin intake ameliorates changes in muscle damage markers following a soccer match while controlling for the potential confounding factors.

METHODS

Fifteen collegiate athletes were tested in a randomized, double-blind, cross-over manner. They were recruited from the same college soccer team and thus followed the same daily training regimen and competition levels. Furthermore, athletes positioning during matches were counterbalanced. They consumed either 180 mg/day of curcumin or a placebo starting 1 h before the match and continuing for 2 days after a match (two 45-min plays and a 15-min half-time). Muscle soreness, jump performance (including countermovement jump and rebound jump index), and inflammatory and muscle damage markers (high-sensitive C-reactive protein, serum creatine kinase activity, and urinary N-terminal fragment of titin concentration) were evaluated before and after the match. The washout period between matches was set at 1 week.

RESULTS

After the match, all markers showed similarity between the placebo and curcumin conditions (all P > 0.208).

CONCLUSION

These findings indicate that ingesting 180 mg/day of curcumin may not expedite recovery from muscle damage elicited by soccer matches in collegiate soccer players.

Curcumin and targeting of molecular and metabolic pathways in multiple sclerosis

Multiple sclerosis (MS) is a life-threading disease that poses a great threat to the human being lifestyle. Having said extensive research in the realm of underlying mechanisms and treatment procedures, no definite remedy has been found. Over the past decades, many medicines have been disclosed to alleviate the symptoms and marking of MS. Meanwhile, the substantial efficacy of herbal medicines including curcumin must be underscored. Accumulated documents demonstrated the fundamental role of curcumin in the induction of the various signaling pathways. According to evidence, curcumin can play a role in mitochondrial dysfunction and apoptosis, autophagy, and mitophagy. Also, by targeting the signaling pathways AMPK, PGC-1α/PPARγ, and PI3K/Akt/mTOR, curcumin interferes with the metabolism of MS. The anti-inflammatory, antioxidant, and immune regulatory effects of this herbal compound are involved in its effectiveness against MS. Thus, the present review indicates the molecular and metabolic pathways associated with curcumin's various pharmacological actions on MS, as well as setting into context the many investigations that have noted curcumin-mediated regulatory effects in MS.

Inhibition of BACE1 attenuates microglia-induced neuroinflammation after intracerebral hemorrhage by suppressing STAT3 activation

Hematoma-induced neuroinflammation is the cause of poor prognosis in intracerebral hemorrhage (ICH); therefore, promoting blood clearance and blocking overactivated inflammation are rational approaches for ICH treatment. β-site amyloid precursor protein (APP) lyase-1 (BACE1) is a key molecule regulating the microglial phenotype transition in neurodegenerative diseases. Therefore, the aim of this study was to investigate the role of BACE1 in microglial phagocytosis and inflammatory features in ICH. Here, we demonstrated the unique advantages of targeting BACE1 in microglia using an autologous blood model and primary microglia hemoglobin stimulation. When BACE1 was inhibited early in ICH, fewer residual hematomas remained, consistent with an increase in genetic features that favor phagocytosis and anti-inflammation. In addition, inhibition of BACE1 enhanced the secretion of anti-inflammatory cytokines and substantially reduced the expression of proinflammatory genes, which was regulated by signal transduction and phosphorylation of activator of transcription 3 (STAT3). Further pharmacological inhibition of STAT3 phosphorylation effectively blocked the proinflammatory and weak phagocytic phenotype of microglia due to BACE1 induction. In summary, BACE1 is the critical molecule regulating the inflammatory and phagocytic phenotypes of microglia after ICH, and targeted inhibition of the BACE1/STAT3 pathway is an important strategy for the future treatment of ICH-induced neurological injury.

Metformin and curcumin co-encapsulated chitosan/alginate nanoparticles as effective oral carriers against pain-like behaviors in mice

Nanotechnology plays an integral role in multimodal analgesia. In this study, we co-encapsulated metformin (Met) and curcumin (Cur) into chitosan/alginate (CTS/ALG) nanoparticles (NPs) at their synergistic drug ratio by applying response surface methodology. The optimized Met-Cur-CTS/ALG-NPs were achieved with Pluronic® F-127 2.33% (w/v), Met 5.91 mg, and CTS:ALG mass ratio 0.05:1. The prepared Met-Cur-CTS/ALG-NPs had 243 nm particle size, -21.6 mV zeta potential, 32.6 and 44.2% Met and Cur encapsulations, 19.6 and 6.8% Met and Cur loading, respectively, and 2.9:1 Met:Cur mass ratio. Met-Cur-CTS/ALG-NPs displayed stability under simulated gastrointestinal (GI) fluid conditions and during storage. In vitro release study of Met-Cur-CTS/ALG-NPs in simulated GI fluids showed sustained release, with Met exhibiting Fickian diffusion and Cur demonstrating non-Fickian diffusion following the Korsmeyer-Peppas model. Met-Cur-CTS/ALG-NPs exhibited increased mucoadhesion and improved cellular uptake in Caco-2 cells. Additionally, Met-Cur-CTS/ALG-NPs exhibited better anti-inflammatory effects in lipopolysaccharide-stimulated RAW 264.7 macrophage and BV-2 microglial cells than the equivalent amount of the Met-Cur physical mixture, indicating a greater ability to modulate peripheral and central immune mechanisms of pain. In the mouse formalin-induced pain model, Met-Cur-CTS/ALG-NPs administered orally exhibited better attenuation of pain-like behaviors and proinflammatory cytokine release compared to the Met-Cur physical mixture. Furthermore, Met-Cur-CTS/ALG-NPs did not induce significant side effects in mice at therapeutic doses. Altogether, the present study establishes a CTS/ALG nano-delivery system for Met-Cur combination against pain with improved efficacy and safety.

The combination of Alisma and Atractylodes ameliorates cerebral ischaemia/reperfusion injury by negatively regulating astrocyte-derived exosomal miR-200a-3p/141-3p by targeting SIRT1

ETHNOPHARMACOLOGICAL RELEVANCE

The combination of Alisma and Atractylodes (AA), a classical traditional Chinese herbal decoction, may protect against cerebral ischaemia/reperfusion injury (CIRI). However, the underlying mechanism has not been characterized. Intriguingly, exosomal microRNAs (miRNAs) have been recognized as vital factors in the pharmacology of Chinese herbal decoctions.

AIM OF THE STUDY

The aim of the present study was to assess whether the neuroprotective effect of AA was dependent on the efficient transfer of miRNAs via exosomes in the brain.

MATERIALS AND METHODS

Bilateral common carotid artery ligation (BCAL) was used to induce transient global cerebral ischaemia/reperfusion (GCI/R) in C57BL/6 mice treated with/without AA. Neurological deficits were assessed with the modified neurological severity score (mNSS) and Morris water maze (MWM) test. Western blot (WB) analysis was used to detect the expression of sirtuin 1 (SIRT1) in the cerebral cortex. The inflammatory state was quantitatively evaluated by measuring the expression of phospho-Nuclear factor kappa B (p-NF-κB), Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) using WB analysis and glial fibrillary acidic protein (GFAP) immunohistochemical staining. The protein expression of zonula occluden-1 (ZO-1), occludin, caudin-5 and CD31 was examined by immunohistochemical staining to determine blood‒brain barrier (BBB) permeability. Exosomes were extracted from the brain interstitial space by ultracentrifugation and identified by transmission electron microscopy (TEM), WB analysis and nanoparticle tracking analysis (NTA). The origin of exosomes was clarified by measuring the specific mRNAs within exosomes via Real Time Quantitative PCR (RT‒qPCR). Differential miRNAs in exosomes were identified using microarray screening and were validated by RT‒qPCR. Exosomes were labelled with fluorescent dye (PKH26) and incubated with bEnd.3 cells, the supernatant was collected, IL-1β/TNF-α expression was measured using enzyme-linked immunosorbent assay (ELISA), total RNA was extracted, and miR-200a-3p/141-3p expression was examined by RT‒qPCR. In addition, the levels of miR-200a-3p/141-3p in oxygen glucose deprivation/reoxygenation (OGD/R)-induced bEnd.3 cells were quantified. The direct interaction between miR-200a-3p/141-3p and the SIRT1 3' untranslated region (3'UTR) was measured by determining SIRT1 expression in bEnd.3 cells transfected with the miR-200a-3p/141-3p mimic/inhibitor.

RESULTS

Severe neurological deficits and memory loss caused by GCI/R in mice was markedly ameliorated by AA treatment, particularly in the AA medium-dose group. Moreover, AA-treated GCI/R-induced mice showed significant increases in SIRT1, ZO-1, occludin, caudin-5, and CD31 expression levels and decreases in p-NF-κB, IL-1β, TNF-α, and GFAP expression levels compared with those in untreated GCI/R-induced mice. Furthermore, we found that miR-200a-3p/141-3p was enriched in astrocyte-derived exosomes from GCI/R-induced mice and could be inhibited by treatment with a medium dose of AA. The exosomes mediated the transfer of miR-200a-3p/141-3p into bEnd.3 cells, promoted IL-1β and TNF-α release and downregulated the expression of SIRT1. No significant changes in the levels of miR-200a-3p/141-3p were observed in OGD/R-induced bEnd.3 cells. The miR-200a-3p/141-3p mimic/inhibitor decreased/increased SIRT1 expression in bEnd.3 cells, respectively.

CONCLUSION

Our findings demonstrated that AA attenuated inflammation-mediated CIRI by inhibiting astrocyte-derived exosomal miR-200a-3p/141-3p by targeting the SIRT1 gene, which provided further evidence and identified a novel regulatory mechanism for the neuroprotective effects of AA.

An Integrative Approach to Investigate the Mode of Action of (-)-Dendroparishiol in Bacterial Meningitis: Computer-Aided Estimation of Biological Activity and Network Pharmacology

Bacterial meningitis remains one of the most prevalent infectious diseases worldwide. Although advances in medical care have improved mortality and morbidity, neurological complications remain high. Therefore, aside from antibiotics, therapeutic adjuvants targeting neuroinflammation are essential to combat the long-term neuronal sequelae of bacterial meningitis. In the present study, we propose (-)-dendroparishiol as a potential add-on therapy to improve neuroinflammation associated with bacterial meningitis. The biological activity of (-)-dendroparishiol was first predicted by computational analysis and further confirmed in vitro using a cell-based assay with LPS-induced BV-2 microglial cells. Biological pathways involved with (-)-dendroparishiol were identified by applying network pharmacology. Computational predictions of biological activity indicated possible attenuation of several inflammatory processes by (-)-dendroparishiol. In LPS-induced BV-2 microglial cells, (-)-dendroparishiol significantly reduced the expression of inflammatory mediators: iNOS, NO, COX-2, IL-6, and TNF-α. Molecular docking results demonstrated the potential iNOS and COX-2 inhibitory activity of (-)-dendroparishiol. Network pharmacological analysis indicated the plausible role of (-)-dendroparishiol in biological processes involved in oxidative stress and neuroinflammation with enrichment in neuroinflammatory pathways. Overall, this study provides scientific evidence for the potential application of (-)-dendroparishiol in the management of bacterial meningitis-associated neuroinflammation.

Preliminary Study on the Antioxidant Effect of Natural Based Products with Potential Application in Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) is a complex condition characterized by chronic pain and various sensory, motor, and autonomic symptoms. It involves a complex interplay of mechanisms in the nervous system, including neuroinflammation, sensitization of pain pathways, and dysfunction of the sympathetic nervous system. Antioxidants may play a role in CRPS by helping to counteract oxidative stress, which is an imbalance between the production of reactive oxygen species (ROS) and the body's antioxidant defences. CRPS involves inflammation and tissue damage, which can lead to increased ROS production and oxidative stress. Our paper represents a preliminary study on various commercially available natural-based products regarding their antioxidant effect. Several natural products with antioxidant properties, such as vitamins C and E, polyphenols, flavonoids, and botanical extracts, have shown promise in preclinical studies for their potential to alleviate pain and reduce inflammation associated with CRPS. The potential use of natural-based products with antioxidant effects for mitigating CRPS symptoms is still an area of ongoing research and investigation, but nonetheless it holds promise.

Is Curcumine Useful in the Treatment and Prevention of the Tendinopathy and Myotendinous Junction Injury? A Scoping Review

Physical activity in general and sports in particular, is a mechanism that produces stress and generates great force in the tendon and in the muscle-tendon unit, which increases the risk of injury (tendinopathies). Eccentric and repetitive contraction of the muscle precipitates persistent microtraumatism in the tendon unit. In the development of tendinopathies, the cellular process includes inflammation, apoptosis, vascular, and neuronal changes. Currently, treatments with oral supplements are frequently used. Curcumin seems to preserve, and even repair, damaged tendons. In this systematic review, we focus more especially on the benefits of curcumin. The biological actions of curcumin are diverse, but act around three systems: (a) inflammatory, (b) nuclear factor B (NF-κB) related apoptosis pathways, and (c) oxidative stress systems. A bibliographic search is conducted under the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) as a basis for reporting reliable systematic reviews to perform a Scoping review. After analysing the manuscripts, we can conclude that curcumin is a product that demonstrates a significant biological antialgic, anti-inflammatory, and antioxidant power. Therefore, supplementation has a positive effect on the inflammatory and regenerative response in tendinopathies. In addition, curcumin decreases and modulates the cell infiltration, activation, and maturation of leukocytes, as well as the production of pro-inflammatory mediators at the site of inflammation.

Combination of curcumin and piperine synergistically improves pain-like behaviors in mouse models of pain with no potential CNS side effects

Background

Curcumin and piperine are major bioactive compounds of Curcuma longa and Piper nigrum, widely consumed as spices and flock medicine. The combinational use of these plants is a common practice in Southeast Asia. Synergism between curcumin and piperine has been found in several animal models but not in periodontal disease and diabetes, and the antinociceptive interaction is still unknown. Hence, the present study aimed to assess the interaction between curcumin and piperine in pain and its potential CNS side effect profile.

Methods

Formalin test and in vitro LPS-stimulated RAW 264.7 macrophage cells were used to assess the synergistic interaction of curcumin and piperine in a mouse model of inflammatory pain. Tail-flick and cold plate tests were applied to determine the antinociceptive synergism between piperine and curcumin. The interaction was determined by applying isobolographic analysis. The potential CNS-side effects of the curcumin and piperine combination were also assessed using LABORAS automated home-cage behavioral analysis.

Results

Curcumin alone dose-dependently improved pain-like behaviors in the formalin, tail-flick, and cold plate tests with the ED₅₀ of 71.4, 34.4, and 31.9 mg/kg, respectively. Additionally, piperine exhibited efficacy in the formalin, tail-flick, and cold plate tests with the ED₅₀ of 18.4, 8.1, and 28.1 mg/kg, respectively. The combination of curcumin and piperine (1:1 ED₅₀ ratio) produced synergistic interaction in the formalin, tail-flick, and cold plate tests as assessed significantly lower experimental ED₅₀ values (5.9, 5.2, and 5.5 mg/kg) compared to theoretical ED₅₀ values (44.9, 21.3, and 30.0 mg/kg), isobologram analysis, and interaction index values of 0.13, 0.24 and 0.18, respectively. The synergistic interaction of curcumin and piperine was further confirmed by the efficacy of the combination in LPS-stimulated RAW 264.7 macrophage cells. Curcumin and piperine interacted synergistically, reducing proinflammatory mediators. The combination also demonstrated better compatibility profiles with neuronal cells. Furthermore, the curcumin-piperine combination had no effects on mouse spontaneous locomotor behaviors in LABORAS automated home cage monitoring.

Conclusion

Overall, the present study demonstrates strong antinociceptive synergism between curcumin and piperine in mouse models with no potential CNS side effects, suggesting its possible use in clinical trials.

The Efficacy of Curcumin Patch as an Adjuvant Therapeutic Agent in Managing Acute Orofacial Pain on the Post-Cleft Lip and Cleft Palate Surgery Patients: A Pragmatic Trial

OBJECTIVE

 Acute pain is one of the most common pains experienced by post-cleft lip or cleft surgery patients regardless of the administration of analgesic agents. This current study aimed to evaluate the efficacy of a curcumin patch as an adjuvant analgesic agent on the post-cleft lip and cleft palate surgery patients.

MATERIALS AND METHODS

 Fifty-five (33 male; 22 female) participants aged 36 months or less are recruited in this pragmatic trial and randomly assigned to a control group, where no curcumin patch was applied; or the experimental group, where the participants wore a curcumin patch with a dosage of 100mg. All participants (regardless of the group) received a standardized postsurgery analgesic agent immediately after the surgery was completed. A face, leg, activity, cry, and consolability (FLACC) scale was used to evaluate pain levels for three subsequent time points.

STATISTICAL ANALYSIS

 All data were then analyzed by using the Mann-Whitney U test to compare the mean differences between the two groups.

RESULTS

 The results of the current study revealed that there was no significant difference found between the control and the experimental group when mean pain scores were compared for the first evaluation time. Yet, there was a significant difference (p<0.01) between the two groups' mean pain scores on the second evaluation time.

CONCLUSION

 Curcumin patch was found to be effective when used as an adjuvant analgesic agent to reduce acute-orofacial postsurgery pain in cleft lip and cleft surgery patients.

Curcumin Diethyl γ-Aminobutyrate, a Prodrug of Curcumin, for Enhanced Treatment of Inflammatory Pain

Curcumin is a naturally occurring polyphenol compound with potential analgesic effects. It has been shown to improve pain-like behaviors in numerous models of pain. Despite its potential, curcumin exhibits poor physicochemical and pharmacokinetic properties, which hinder its oral therapeutic efficacy. Curcumin diethyl γ-aminobutyrate (CUR-2GE), a carbamate prodrug of curcumin, was designed to overcome these limitations and demonstrated greater anti-neuroinflammatory effects compared to curcumin in vitro. Thus, this study evaluated the effect of CUR-2GE and its parent compound on pain-like behaviors in carrageenan- and LPS-induced mouse models. The possible side effects of CUR-2GE were also assessed by exploring its effects on motor coordination and spontaneous locomotor activity after acute and chronic treatments. The results showed that CUR-2GE improved mechanical and thermal hyperalgesia and locomotor activity to a greater extent than curcumin in carrageenan-induced mice. These results are in line with the ability of CUR-2GE to suppress peripheral inflammation in the paw tissue of carrageenan-induced mice, indicated by a significant decrease in TNF-α and IL-6 expression levels. Similarly, in LPS-induced mice, CUR-2GE improved sickness and pain-like behaviors (exploratory behaviors and long-term locomotor activity) to a greater extent than curcumin. Furthermore, CUR-2GE significantly reduced the level of proinflammatory cytokines in both the plasma and spinal cord tissue of LPS-induced mice, exhibiting significantly higher inhibition than curcumin. Moreover, the motor coordination, and locomotive behaviors of mice were not affected by both acute and chronic administration of CUR-2GE, indicating no potential CNS side effects. Thus, CUR-2GE demonstrated enhanced therapeutic efficacy in mouse models of inflammatory pain without any possible CNS side effects, suggesting its potential to be developed as an analgesic agent against inflammatory pain.

Curcumin and metformin synergistically modulate peripheral and central immune mechanisms of pain

Metformin is a well-tolerated antidiabetic drug and has recently been repurposed for numerous diseases, including pain. However, a higher dose of metformin is required for effective analgesia, which can potentiate its dose-dependent gastrointestinal side effects. Curcumin is a natural polyphenol and has beneficial therapeutic effects on pain. Curcumin has been used as an analgesic adjuvant with several analgesic drugs, allowing synergistic antinociceptive effects. Nevertheless, whether curcumin can exert synergistic analgesia with metformin is still unknown. In the present study, the nature of curcumin-metformin anti-inflammatory interaction was evaluated in in vitro using lipopolysaccharide-induced RAW 264.7 macrophage and BV-2 microglia cells. In both macrophage and microglia, curcumin effectively potentiates the anti-inflammatory effects of metformin, indicating potential synergistic effects in both peripheral and central pathways of pain. The nature of the interaction between curcumin and metformin was further recapitulated using a mouse model of formalin-induced pain. Coadministration of curcumin and metformin at a 1:1 fixed ratio of their ED₅₀ doses significantly reduced the dose required to produce a 50% effect compared to the theoretically required dose in phase II of the formalin test with a combination index value of 0.24. Besides, the synergistic interaction does not appear to involve severe CNS side effects indicated by no motor alterations, no alterations in short-term and long-term locomotive behaviors, and the general well-being of mice. Our findings suggest that curcumin exerts synergistic anti-inflammation with metformin with no potential CNS adverse effects.

Inflammaging and Brain: Curcumin and Its Beneficial Potential as Regulator of Microglia Activation

Inflammaging is a term used to describe the tight relationship between low-grade chronic inflammation and aging that occurs during physiological aging in the absence of evident infection. This condition has been linked to a broad spectrum of age-related disorders in various organs including the brain. Inflammaging represents a highly significant risk factor for the development and progression of age-related conditions, including neurodegenerative diseases which are characterized by the progressive dysfunction and degeneration of neurons in the brain and peripheral nervous system. Curcumin is a widely studied polyphenol isolated from Curcuma longa with a variety of pharmacologic properties. It is well-known for its healing properties and has been extensively used in Asian medicine to treat a variety of illness conditions. The number of studies that suggest beneficial effects of curcumin on brain pathologies and age-related diseases is increasing. Curcumin is able to inhibit the formation of reactive-oxygen species and other pro-inflammatory mediators that are believed to play a pivotal role in many age-related diseases. Curcumin has been recently proposed as a potential useful remedy against neurodegenerative disorders and brain ageing. In light of this, our current review aims to discuss the potential positive effects of Curcumin on the possibility to control inflammaging emphasizing the possible modulation of inflammaging processes in neurodegenerative diseases.

Dietary Supplementation for Attenuating Exercise-Induced Muscle Damage and Delayed-Onset Muscle Soreness in Humans

Dietary supplements are widely used as a nutritional strategy to improve and maintain performance and achieve faster recovery in sports and exercise. Exercise-induced muscle damage (EIMD) is caused by mechanical stress and subsequent inflammatory responses including reactive oxygen species and cytokine production. Therefore, dietary supplements with anti-inflammatory and antioxidant properties have the potential to prevent and reduce muscle damage and symptoms characterized by loss of muscle strength and delayed-onset muscle soreness (DOMS). However, only a few supplements are considered to be effective at present. This review focuses on the effects of dietary supplements derived from phytochemicals and listed in the International Olympic Committee consensus statement on muscle damage evaluated by blood myofiber damage markers, muscle soreness, performance, and inflammatory and oxidative stress markers. In this review, the effects of dietary supplements are also discussed in terms of study design (i.e., parallel and crossover studies), exercise model, and such subject characteristics as physical fitness level. Future perspectives and considerations for the use of dietary supplements to alleviate EIMD and DOMS are also discussed.