Curcumin Attenuates the Expression and Secretion of RANTES after Spinal Cord Injury In Vivo and Lipopolysaccharide-Induced Astrocyte Reactivation In Vitro

The secondary injury cascade after spinal cord injury: an analysis of local cytokine/chemokine regulation

JOURNAL/nrgr/04.03/01300535-202406000-00035/inline-graphic1/v/2023-10-30T152229Z/r/image-tiff

After spinal cord injury, there is an extensive infiltration of immune cells, which exacerbates the injury and leads to further neural degeneration. Therefore, a major aim of current research involves targeting the immune response as a treatment for spinal cord injury. Although much research has been performed analyzing the complex inflammatory process following spinal cord injury, there remain major discrepancies within previous literature regarding the timeline of local cytokine regulation. The objectives of this study were to establish an overview of the timeline of cytokine regulation for 2 weeks after spinal cord injury, identify sexual dimorphisms in terms of cytokine levels, and determine local cytokines that significantly change based on the severity of spinal cord injury. Rats were inflicted with either a mild contusion, moderate contusion, severe contusion, or complete transection, 7 mm of spinal cord centered on the injury was harvested at varying times post-injury, and tissue homogenates were analyzed with a Cytokine/Chemokine 27-Plex assay. Results demonstrated pro-inflammatory cytokines including tumor necrosis factor α, interleukin-1β, and interleukin-6 were all upregulated after spinal cord injury, but returned to uninjured levels within approximately 24 hours post-injury, while chemokines including monocyte chemoattractant protein-1 remained upregulated for days post-injury. In contrast, several anti-inflammatory cytokines and growth factors including interleukin-10 and vascular endothelial growth factor were downregulated by 7 days post-injury. After spinal cord injury, tissue inhibitor of metalloproteinase-1, which specifically affects astrocytes involved in glial scar development, increased more than all other cytokines tested, reaching 26.9-fold higher than uninjured rats. After a mild injury, 11 cytokines demonstrated sexual dimorphisms; however, after a severe contusion only leptin levels were different between female and male rats. In conclusion, pro-inflammatory cytokines initiate the inflammatory process and return to baseline within hours post-injury, chemokines continue to recruit immune cells for days post-injury, while anti-inflammatory cytokines are downregulated by a week post-injury, and sexual dimorphisms observed after mild injury subsided with more severe injuries. Results from this work define critical chemokines that influence immune cell infiltration and important cytokines involved in glial scar development after spinal cord injury, which are essential for researchers developing treatments targeting secondary damage after spinal cord injury.

Sustainable inflammatory activation following spinal cord injury is driven by thrombin-mediated dynamic expression of astrocytic chemokines

Acute spinal cord injury (SCI) always results in sustainable recruitment of inflammatory cells driven by sequentially generated chemokines, thereby eliciting excessive neuroinflammation. However, the underlying mechanism of temporally produced chemokines remains elusive. Reactive astrocytes are known to be the main sources of chemokines at the lesion site, which can be immediately activated by thrombin following SCI. In the present study, SCI was shown to induce a sequential production of chemokines CCL2 and CCL5 from astrocytes, which were associated with a persistent infiltration of macrophages/microglia. The rapidly induced CCL2 and later induced CCL5 from astrocytes were regulated by thrombin at the damaged tissues. Investigation of the regulatory mechanism revealed that thrombin facilitated astrocytic CCL2 production through activation of ERK/JNK/NFκB pathway, whereas promoted CCL5 production through PLCβ3/NFκB and ERK/JNK/NFκB signal pathway. Inhibition of thrombin activity significantly decreased production of astrocytic CCL2 and CCL5, and reduced the accumulation of macrophages/microglia at the lesion site. Accordingly, the locomotor function of rats was remarkably improved. The present study has provided a new regulatory mechanism on thrombin-mediated sequential production of astrocytic chemokines, which might be beneficial for clinical therapy of CNS neuroinflammation.

Curcumin and chemokines: mechanism of action and therapeutic potential in inflammatory diseases

Chemokines belong to the family of cytokines with chemoattractant properties that regulate chemotaxis and leukocyte migration, as well as the induction of angiogenesis and maintenance of hemostasis. Curcumin, the major component of the Curcuma longa rhizome, has various pharmacological actions, including anti-inflammatory, immune-regulatory, anti-oxidative, and lipid-modifying properties. Chemokines and chemokine receptors are influenced/modulated by curcumin. Thus, the current review focuses on the molecular mechanisms associated with curcumin's effects on chemoattractant cytokines, as well as putting into context the many studies that have reported curcumin-mediated regulatory effects on inflammatory conditions in the organs/systems of the body (e.g., the central nervous system, liver, and cardiovascular system). Curcumin's effects on viral and bacterial infections, cancer, and adverse pregnancy outcomes are also reviewed.

Transcriptional and Chromatin Accessibility Profiling of Neural Stem Cells Differentiating into Astrocytes Reveal Dynamic Signatures Affected under Inflammatory Conditions

Astrocytes arise from multipotent neural stem cells (NSCs) and represent the most abundant cell type of the central nervous system (CNS), playing key roles in the developing and adult brain. Since the differentiation of NSCs towards a gliogenic fate is a precisely timed and regulated process, its perturbation gives rise to dysfunctional astrocytic phenotypes. Inflammation, which often underlies neurological disorders, including neurodevelopmental disorders and brain tumors, disrupts the accurate developmental process of NSCs. However, the specific consequences of an inflammatory environment on the epigenetic and transcriptional programs underlying NSCs' differentiation into astrocytes is unexplored. Here, we address this gap by profiling in mice glial precursors from neural tissue derived from early embryonic stages along their astrocytic differentiation trajectory in the presence or absence of tumor necrosis factor (TNF), a master pro-inflammatory cytokine. By using a combination of RNA- and ATAC-sequencing approaches, together with footprint and integrated gene regulatory network analyses, we here identify key differences during the differentiation of NSCs into astrocytes under physiological and inflammatory settings. In agreement with its role to turn cells resistant to inflammatory challenges, we detect Nrf2 as a master transcription factor supporting the astrocytic differentiation under TNF exposure. Further, under these conditions, we unravel additional transcriptional regulatory hubs, including Stat3, Smad3, Cebpb, and Nfkb2, highlighting the interplay among pathways underlying physiological astrocytic developmental processes and those involved in inflammatory responses, resulting in discrete astrocytic phenotypes. Overall, our study reports key transcriptional and epigenetic changes leading to the identification of molecular regulators of astrocytic differentiation. Furthermore, our analyses provide a valuable resource for understanding inflammation-induced astrocytic phenotypes that might contribute to the development and progression of CNS disorders with an inflammatory component.

IL1RAP Knockdown in LPS-Stimulated Normal Human Astrocytes Suppresses LPS-Induced Reactive Astrogliosis and Promotes Neuronal Cell Proliferation

The reactivation of astrocytes plays a critical role in spinal cord injury (SCI) repairment. In this study, IL1RAP expression has been found to be upregulated in SCI mice spinal cord, SCI astrocytes, and LPS-stimulated NHAs. Genes correlated with IL1RAP were significantly enriched in cell proliferation relative pathways. In LPS-stimulated NHAs, IL1RAP overexpression promoted NHA cell proliferation, decreased PTEN protein levels, and increased the phosphorylation of Akt and mTOR. IL1RAP overexpression promoted LPS-induced NHA activation and NF-κB signaling activation. Conditioned medium from IL1RAP-overexpressing NHAs inhibited SH-SY5Y cells viability but promoted cell apoptosis. Conclusively, IL1RAP knockdown in LPS-stimulated NHAs could partially suppress LPS-induced reactive astrogliosis, therefore promoting neuronal cell proliferation.

Protective effects of curcumin on ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is a term used to describe phenomena connected to the dysfunction of various tissue damage due to reperfusion after ischemic injury. While I/R may result in systemic inflammatory response syndrome or multiple organ dysfunction syndrome, there is still a long way to improve therapeutic outcomes. A number of cellular metabolic and ultrastructural alterations occur by prolonged ischemia. Ischemia increases the expression of proinflammatory gene products and bioactive substances within the endothelium, such as cytokines, leukocytes, and adhesion molecules, even as suppressing the expression of other "protective" gene products and substances, such as thrombomodulin and constitutive nitric oxide synthase (e.g., prostacyclin, nitric oxide [NO]). Curcumin is the primary phenolic pigment derived from turmeric, the powdered rhizome of Curcuma longa. Numerous studies have shown that curcumin has strong antiinflammatory and antioxidant characteristics. It also prevents lipid peroxidation and scavenges free radicals like superoxide anion, singlet oxygen, NO, and hydroxyl. In our study, we highlight the mechanisms of protective effects of curcumin against I/R injury in various organs.

Curcumin Facilitates Aryl Hydrocarbon Receptor Activation to Ameliorate Inflammatory Astrogliosis

Curcumin is an anti-inflammatory and neuroprotective compound in turmeric. It is a potential ligand of the aryl hydrocarbon receptor (AhR) that mediates anti-inflammatory signaling. However, the AhR-mediated anti-inflammatory effect of curcumin within the brain remains unclear. We investigated the role of AhR on the curcumin effect in inflammatory astrogliosis. Curcumin attenuated lipopolysaccharide (LPS)-induced proinflammatory IL-6 and TNF-α gene expression in primary cultured rat astrocytes. When AhR was knocked down, LPS-induced IL-6 and TNF-α were increased and curcumin-decreased activation of the inflammation mediator NF-κB p65 by LPS was abolished. Although LPS increased AhR and its target gene CYP1B1, curcumin further enhanced LPS-induced CYP1B1 and indoleamine 2,3-dioxygenase (IDO), which metabolizes tryptophan to AhR ligands kynurenine (KYN) and kynurenic acid (KYNA). Potential interactions between curcumin and human AhR analyzed by molecular modeling of ligand-receptor docking. We identified a new ligand binding site on AhR different from the classical 2,3,7,8-tetrachlorodibenzo-p-dioxin site. Curcumin docked onto the classical binding site, whereas KYN and KYNA occupied the novel one. Moreover, curcumin and KYNA collaboratively bound onto AhR during molecular docking, potentially resulting in synergistic effects influencing AhR activation. Curcumin may enhance the inflammation-induced IDO/KYN axis and allosterically regulate endogenous ligand binding to AhR, facilitating AhR activation to regulate inflammatory astrogliosis.

Anti-Inflammatory CDGSH Iron-Sulfur Domain 2: A Biomarker of Central Nervous System Insult in Cellular, Animal Models and Patients

Spinal cord injury (SCI) promotes brain inflammation; conversely, brain injury promotes spinal neuron loss. There is a need to identify molecular biomarkers and therapeutic targets for central nervous system (CNS) injury. CDGSH iron-sulfur structural domain 2 (CISD2), an NF-κB antagonist, is downregulated after injury in vivo and in vitro. We aimed to examine the diagnostic value of CISD2 in patients with CNS insult. Plasma and cerebrospinal fluid (CSF) CISD2 levels were decreased in 13 patients with CNS insult and were negatively correlated with plasma IL6 levels (associated with disease severity; r = −0.7062; p < 0.01). SCI-induced inflammatory mediators delivered through CSF promoted mouse brain inflammation at 1 h post-SCI. Anti-CISD2 antibody treatment exacerbated SCI-induced inflammation in mouse spine and brain. Lipopolysaccharide-stimulated siCISD2-transfected EOC microglial cells exhibited proinflammatory phenotypes (enhanced M1 polarization, decreased M2 polarization, and increased intranuclear NF-κB p65 translocation). Plasma and CSF CISD2 levels were increased in three patients with CNS insult post-therapeutic hypothermia. CISD2 levels were negatively correlated with plasma and CSF levels of inflammatory mediators. CISD2 inhibition and potentiation experiments in cells, animals, and humans revealed CISD2 as a biomarker for CNS insult and upregulation of CISD2 anti-inflammatory properties as a potential therapeutic strategy for CNS insult.

Freshwater Clam Extract Mitigates Neuroinflammation and Amplifies Neurotrophic Activity of Glia: Insights from In Vitro Model of Neurodegenerative Pathomechanism

Background. An extensive body of research suggests that brain inflammation and oxidative stress are the underlying causes of Parkinson’s disease (PD), for which no potent therapeutic approach exists to mitigate the degradation of dopamine neurons. Freshwater clams, an ancient health food of Chinese origin, have been documented to exhibit anti-inflammatory and antioxidant effects. We previously reported that freshwater clam extract (FCE) can attenuate astrocytic activation and subsequent proinflammatory cytokine production from substantia nigra in an MPTP-induced PD mouse model. This article provides insight into the potential mechanisms through which FCE regulates neuroinflammation in a glia model of injury. Materials and methods. In total, 1 μg/mL lipopolysaccharide (LPS) and 200 μM rotenone were conducted in primary glial cell cultures to mimic the respective neuroinflammation and oxidative stress during injury-induced glial cell reactivation, which is relevant to the pathological process of PD. Results. FCE markedly reduced LPS-induced neuroinflammation by suppressing NO and TNF-α production and the expression of pro-inflammatory cytokines. In addition, FCE was effective at reducing rotenone-induced toxicity by diminishing ROS production, promoting antioxidant enzymes (SOD, catalase, and GPx) and minimizing the decline in glial-cell-secreted neurotrophic factors (GDNF, BDNF). These impacts ultimately led to a decrease in glial apoptosis. Conclusions. Evidence reveals that FCE is capable of stabilizing reactive glia, as demonstrated by reduced neuroinflammation, oxidative stress, the increased release of neurotrophic factors and the inhibition of apoptosis, which provides therapeutic insight into neurodegenerative diseases, including PD.

Effects of Polyphenols on Oxidative Stress, Inflammation, and Interconnected Pathways during Spinal Cord Injury

Despite the progression in targeting the complex pathophysiological mechanisms of neurodegenerative diseases (NDDs) and spinal cord injury (SCI), there is a lack of effective treatments. Moreover, conventional therapies suffer from associated side effects and low efficacy, raising the need for finding potential alternative therapies. In this regard, a comprehensive review was done regarding revealing the main neurological dysregulated pathways and providing alternative therapeutic agents following SCI. From the mechanistic point, oxidative stress and inflammatory pathways are major upstream orchestras of cross-linked dysregulated pathways (e.g., apoptosis, autophagy, and extrinsic mechanisms) following SCI. It urges the need for developing multitarget therapies against SCI complications. Polyphenols, as plant-derived secondary metabolites, have the potential of being introduced as alternative therapeutic agents to pave the way for treating SCI. Such secondary metabolites presented modulatory effects on neuronal oxidative stress, neuroinflammatory, and extrinsic axonal dysregulated pathways in the onset and progression of SCI. In the present review, the potential role of phenolic compounds as critical phytochemicals has also been revealed in regulating upstream dysregulated oxidative stress/inflammatory signaling mediators and extrinsic mechanisms of axonal regeneration after SCI in preclinical and clinical studies. Additionally, the coadministration of polyphenols and stem cells has shown a promising strategy for improving post-SCI complications.

Inflammation after spinal cord injury: a review of the critical timeline of signaling cues and cellular infiltration

Traumatic spinal cord injury (SCI) is a devastating neurological condition that results in a loss of motor and sensory function. Although extensive research to develop treatments for SCI has been performed, to date, none of these treatments have produced a meaningful amount of functional recovery after injury. The primary injury is caused by the initial trauma to the spinal cord and results in ischemia, oxidative damage, edema, and glutamate excitotoxicity. This process initiates a secondary injury cascade, which starts just a few hours post-injury and may continue for more than 6 months, leading to additional cell death and spinal cord damage. Inflammation after SCI is complex and driven by a diverse set of cells and signaling molecules. In this review, we utilize an extensive literature survey to develop the timeline of local immune cell and cytokine behavior after SCI in rodent models. We discuss the precise functional roles of several key cytokines and their effects on a variety of cell types involved in the secondary injury cascade. Furthermore, variations in the inflammatory response between rats and mice are highlighted. Since current SCI treatment options do not successfully initiate functional recovery or axonal regeneration, identifying the specific mechanisms attributed to secondary injury is critical. With a more thorough understanding of the complex SCI pathophysiology, effective therapeutic targets with realistic timelines for intervention may be established to successfully attenuate secondary damage.

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

Chronic pain is a persistent and unremitting condition that has immense effects on patients' quality of life. Studies have shown that neuroinflammation is associated with the induction and progression of chronic pain. The activation of microglia and astrocytes is the major hallmark of spinal neuroinflammation leading to neuronal excitability in the projection neurons. Excessive activation of microglia and astrocytes is one of the major contributing factors to the exacerbation of pain. However, the current chronic pain treatments, mainly by targeting the neuronal cells, remain ineffective and unable to meet the patients' needs. Curcumin, a natural plant product found in the Curcuma genus, improves chronic pain by diminishing the release of inflammatory mediators from the spinal glia. This review details the role of curcumin in microglia and astrocytes both in vitro and in vivo and how it improves pain. We also describe the mechanism of curcumin by highlighting the major glia-mediated cascades in pain. Moreover, the role of curcumin on inflammasome and epigenetic regulation is discussed. Furthermore, we discuss the strategies used to improve the efficacy of curcumin. This review illustrates that curcumin modulating microglia and astrocytes could assure the treatment of chronic pain by suppressing spinal neuroinflammation.

Beneficial Impacts of Alpha-Eleostearic Acid from Wild Bitter Melon and Curcumin on Promotion of CDGSH Iron-Sulfur Domain 2: Therapeutic Roles in CNS Injuries and Diseases

Neuroinflammation and abnormal mitochondrial function are related to the cause of aging, neurodegeneration, and neurotrauma. The activation of nuclear factor κB (NF-κB), exaggerating these two pathologies, underlies the pathogenesis for the aforementioned injuries and diseases in the central nervous system (CNS). CDGSH iron-sulfur domain 2 (CISD2) belongs to the human NEET protein family with the [2Fe-2S] cluster. CISD2 has been verified as an NFκB antagonist through the association with peroxisome proliferator-activated receptor-β (PPAR-β). This protective protein can be attenuated under circumstances of CNS injuries and diseases, thereby causing NFκB activation and exaggerating NFκB-provoked neuroinflammation and abnormal mitochondrial function. Consequently, CISD2-elevating plans of action provide pathways in the management of various disease categories. Various bioactive molecules derived from plants exert protective anti-oxidative and anti-inflammatory effects and serve as natural antioxidants, such as conjugated fatty acids and phenolic compounds. Herein, we have summarized pharmacological characters of the two phytochemicals, namely, alpha-eleostearic acid (α-ESA), an isomer of conjugated linolenic acids derived from wild bitter melon (Momordica charantia L. var. abbreviata Ser.), and curcumin, a polyphenol derived from rhizomes of Curcuma longa L. In this review, the unique function of the CISD2-elevating effect of α-ESA and curcumin are particularly emphasized, and these natural compounds are expected to serve as a potential therapeutic target for CNS injuries and diseases.

CISD2 Attenuates Inflammation and Regulates Microglia Polarization in EOC Microglial Cells-As a Potential Therapeutic Target for Neurodegenerative Dementia

Background: Accumulating evidence has demonstrated a significant association between microglia-driven inflammation in the brain and neurodegenerative dementia. We previously showed a significant decline in CISD2 expression in mice models with advanced age. Moreover, we observed that the knockdown of CISD2 led to remarkable inflammation and mitochondrial dysfunction in neural cells. In the present study, we investigated whether CISD2 attenuation influences anti-inflammatory effects and M1-M2 polarization in microglia.

Materials and Methods: The knockdown of CISD2 expression by siRNA (siCISD2) in EOC microglial cells was performed to mimic the age-driven decline of CISD2 expression. The extent of the inflammatory reaction, polarization in the M1/M2 spectrum, and NFκB activation were verified in EOC microglial cells exhibiting CISD2 deficiency.

Results: In the cellular model of microglia, loss of CISD2 function mediated by siCISD2 exhibited a significant augmentation of proinflammatory signaling, as well as reduced expression levels of Arg-1, Ym1, IL-10, and BCL2. Attenuation of CISD2 expression led to a decrease in the proportion of the M2 phenotype of microglia (compared to M1). Enhanced DNA-binding activity of the NFκB p65 subunit was confirmed in cells transfected with siCISD2, as demonstrated by enzyme-linked immunosorbent assay (ELISA).

Conclusions: To the best of our knowledge, this is the first report examining the following phenomena: (1) anti-inflammatory effects of CISD2 in microglia via NFκB regulation; and (2) microglial CISD2 assistance in the restoration of M2 microglia phenotype. The anti-inflammatory effects of CISD2 in microglia eventually augment anti-apoptotic effects, which provides a rationale for the development of potential therapeutic target for neurodegenerative diseases and neurodegenerative dementia.

Effects of curcumin on neurological diseases: focus on astrocytes

Astrocytes are the most abundant glial cells in the central nervous system, and are important players in both brain injury and neurodegenerative disease. Curcumin (1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione), the major active component of turmeric, belongs to the curcuminoid family that was originally isolated from the plant Curcuma longa. Several studies suggest that curcumin may have a beneficial impact on the brain pathology and aging. These effects are due to curcumin's antioxidant, free-radical scavenging, and anti-inflammatory activity. In light of this, our current review aims to discuss the role of astrocytes as essential players in neurodegenerative diseases and suggest that curcumin is capable of direct inhibition of astrocyte activity with a particular focus on its effects in Alexander disease, Alzheimer's disease, ischemia stroke, spinal cord injury, Multiple sclerosis, and Parkinson's disease.

Wild Bitter Melon Exerts Anti-Inflammatory Effects by Upregulating Injury-Attenuated CISD2 Expression following Spinal Cord Injury

BACKGROUND

Spinal cord injuries (SCIs) induce secondary neuroinflammation through astrocyte reactivation, which adversely affects neuronal survival and eventually causes long-term disability. CDGSH iron sulfur domain 2 (CISD2), which has been reported to be involved in mediating the anti-inflammatory responses, can serve as a target in SCI therapy. Wild bitter melon (WBM; Momordica charantia Linn. var. abbreviata Ser.) contains an anti-inflammatory agent called alpha-eleostearic acid (α-ESA), a peroxisome proliferator-activated receptor-β (PPAR-β) ligand. Activated PPAR-β inhibits the nuclear factor κB (NF-κB) signaling pathway via the inhibition of IκB (inhibitor of NF-κB) degradation. The role of astrocyte deactivation and CISD2 in anti-inflammatory mechanisms of WBM in acute SCIs is unknown.

MATERIALS AND METHODS

A mouse model of SCI was generated via spinal cord hemisection. The SCI mice were administered WBM intraperitoneally (500 mg/kg bodyweight). Lipopolysaccharide- (LPS-) stimulated ALT cells (astrocytes) were used as an in vitro model for studying astrocyte-mediated inflammation post-SCI. The roles of CISD2 and PPAR-β in inflammatory signaling were examined using LPS-stimulated SH-SY5Y cells transfected with si-CISD2 or scramble RNA.

RESULTS

WBM mitigated the SCI-induced downregulation of CISD2, PPAR-β, and IκB and upregulation of glial fibrillary acidic protein (GFAP; marker of astrocyte reactivation) in the spinal cord of SCI mice. Additionally, WBM (1 μg/mL) mitigated LPS-induced CISD2 downregulation. Furthermore, SH-SY5Y neural cells with CISD2 knockdown exhibited decreased PPAR-β expression and augmented NF-κB signaling.

CONCLUSION

To the best of our knowledge, this is the first study to report that CISD2 is an upstream modulator of the PPAR-β/NF-κB proinflammatory signaling pathway in neural cells, and that WBM can mitigate the injury-induced downregulation of CISD2 in SCI mice and LPS-stimulated ALT astrocytes.

Effects of Curcumin Nanoparticles in Isoproterenol-Induced Myocardial Infarction

Curcumin has anti-inflammatory, antioxidative, anticarcinogenic, and cardiovascular protective effects. Our study is aimed at evaluating the effects of pretreatment with curcumin nanoparticles (CCNP) compared to conventional curcumin (CC) on isoproterenol (ISO) induced myocardial infarction (MI) in rats. Fifty-six Wistar-Bratislava white rats were randomly divided into eight groups of seven rats each. Curcumin and curcumin nanoparticles were given by gavage in three different doses (100 mg/kg body weight (bw), 150 mg/kg bw, and 200 mg/kg bw) for 15 days. The MI was induced on day 13 using 100 mg/kg bw ISO administered twice, with the second dose 24 h after the initial dose. The blood samples were taken 24 h after the last dose of ISO. The antioxidant, anti-inflammatory, and cardioprotective effects were evaluated in all groups. All doses of CC and CCNP offered a cardioprotective effect by preventing creatine kinase-MB leakage from cardiomyocytes, with the best result for CCNP. All the oxidative stress parameters were significantly improved after CCNP compared to CC pretreatment. CCNP was more efficient than CC in limiting the increase in inflammatory cytokine levels (such as TNF-α, IL-6, IL-1α, IL-1β, MCP-1, and RANTES) after MI. MMP-2 and MMP-9 levels decreased more after pretreatment with CCNP than with CC. CCNP better prevented myocardial necrosis and reduced interstitial edema and neutrophil infiltration than CC, on histopathological examination. Therefore, improving the bioactivity of curcumin by nanotechnology may help limit cardiac injury after myocardial infarction.

Protective Effects of CISD2 and Influence of Curcumin on CISD2 Expression in Aged Animals and Inflammatory Cell Model

BACKGROUND

Inflammation and mitochondrial dysfunction have been linked to trauma, neurodegeneration, and aging. Impairment of CISD2 expression may trigger the aforementioned pathological conditions in neural cells. We previously reported that curcumin attenuates the downregulation of CISD2 in animal models of spinal cord injury and lipopolysaccharide (LPS)-treated neuronal cells. In this study, we investigate (1) the role of CISD2 and (2) how curcumin regulates CISD2 in the aging process.

MATERIALS AND METHODS

The serial expression of CISD2 and the efficacy of curcumin treatment were evaluated in old (104 weeks) mice and long-term cultures of neural cells (35 days in vitro, DIV). LPS-challenged neural cells (with or without siCISD2 transfection) were used to verify the role of curcumin on CISD2 underlying mitochondrial dysfunction.

RESULTS

In the brain and spinal cord of mice aged P2, 8, 25, and 104 weeks, we observed a significant decrease in CISD2 expression with age. Curcumin treatment in vivo and in vitro was shown to upregulate CISD2 expression; attenuate inflammatory response in neural cells. Moreover, curcumin treatment elevated CISD2 expression levels and prevented mitochondrial dysfunction in LPS-challenged neural cells. The beneficial effects of curcumin in either non-stressed or LPS-challenged cells that underwent siCISD2 transfection were significantly lower than in respective groups of cells that underwent scrambled siRNA-transfection.

CONCLUSIONS

We hypothesize that the protective effects of curcumin treatment in reducing cellular inflammation associated trauma, degenerative, and aging processes can be partially attributed to elevated CISD2 expression. We observed a reduction in the protective effects of curcumin against injury-induced inflammation and mitochondrial dysfunction in cells where CISD2 expression was reduced by siCISD2.

Immunomodulators Inspired by Nature: A Review on Curcumin and Echinacea

The immune system is an efficient integrated network of cellular elements and chemicals developed to preserve the integrity of the organism against external insults and its correct functioning and balance are essential to avoid the occurrence of a great variety of disorders. To date, evidence from literature highlights an increase in immunological diseases and a great attention has been focused on the development of molecules able to modulate the immune response. There is an enormous global demand for new effective therapies and researchers are investigating new fields. One promising strategy is the use of herbal medicines as integrative, complementary and preventive therapy. The active components in medical plants have always been an important source of clinical therapeutics and the study of their molecular pharmacology is an enormous challenge since they offer a great chemical diversity with often multi-pharmacological activity. In this review, we mainly analysed the immunomodulatory/antinflammatory activity of Echinacea spp. and Curcuma longa, focusing on some issues of the phytochemical research and on new possible strategies to obtain novel agents to supplement the present therapies.

Protective Effects of Curcumin Against Ischemia-Reperfusion Injury in the Nervous System

Ischemia-reperfusion injury (I/R injury) is a common feature of ischemic stroke which occurs when blood supply is restored after a period of ischemia. Although stroke is an important cause of death in the world, effective therapeutic strategies aiming at improving neurological outcomes in this disease are lacking. Various studies have suggested the involvement of different mechanisms in the pathogenesis of I/R injury in the nervous system. These mechanisms include oxidative stress, platelet adhesion and aggregation, leukocyte infiltration, complement activation, blood-brain barrier (BBB) disruption, and mitochondria-mediated mechanisms. Curcumin, an active ingredient of turmeric, can affect all these pathways and exert neuroprotective activity culminating in the amelioration of I/R injury in the nervous system. In this review, we discuss the protective effects of curcumin against I/R injury in the nervous system and highlight the studies that have linked biological functions of curcumin and I/R injury improvement.

Neuregulin-1 elicits a regulatory immune response following traumatic spinal cord injury

Background

Spinal cord injury (SCI) triggers a robust neuroinflammatory response that governs secondary injury mechanisms with both degenerative and pro-regenerative effects. Identifying new immunomodulatory therapies to promote the supportive aspect of immune response is critically needed for the treatment of SCI. We previously demonstrated that SCI results in acute and permanent depletion of the neuronally derived Neuregulin-1 (Nrg-1) in the spinal cord. Increasing the dysregulated level of Nrg-1 through acute intrathecal Nrg-1 treatment enhanced endogenous cell replacement and promoted white matter preservation and functional recovery in rat SCI. Moreover, we identified a neuroprotective role for Nrg-1 in moderating the activity of resident astrocytes and microglia following injury. To date, the impact of Nrg-1 on immune response in SCI has not yet been investigated. In this study, we elucidated the effect of systemic Nrg-1 therapy on the recruitment and function of macrophages, T cells, and B cells, three major leukocyte populations involved in neuroinflammatory processes following SCI.

Methods

We utilized a clinically relevant model of moderately severe compressive SCI in female Sprague-Dawley rats. Nrg-1 (2 μg/day) or saline was delivered subcutaneously through osmotic mini-pumps starting 30 min after SCI. We conducted flow cytometry, quantitative real-time PCR, and immunohistochemistry at acute, subacute, and chronic stages of SCI to investigate the effects of Nrg-1 treatment on systemic and spinal cord immune response as well as cytokine, chemokine, and antibody production.

Results

We provide novel evidence that Nrg-1 promotes a pro-regenerative immune response after SCI. Bioavailability of Nrg-1 stimulated a regulatory phenotype in T and B cells and augmented the population of M2 macrophages in the spinal cord and blood during the acute and chronic stages of SCI. Importantly, Nrg-1 fostered a more balanced microenvironment in the injured spinal cord by attenuating antibody deposition and expression of pro-inflammatory cytokines and chemokines while upregulating pro-regenerative mediators.

Conclusion

We provide the first evidence of a significant regulatory role for Nrg-1 in neuroinflammation after SCI. Importantly, the present study establishes the promise of systemic Nrg-1 treatment as a candidate immunotherapy for traumatic SCI and other CNS neuroinflammatory conditions.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1093-9) contains supplementary material, which is available to authorized users.

Antidepressants, sertraline and paroxetine, increase calcium influx and induce mitochondrial damage-mediated apoptosis of astrocytes

The impacts of antidepressants on the pathogenesis of dementia remain unclear despite depression and dementia are closely related. Antidepressants have been reported may impair serotonin-regulated adaptive processes, increase neurological side-effects and cytotoxicity. An ‘astroglio-centric’ perspective of neurodegenerative diseases proposes astrocyte dysfunction is involved in the impairment of proper central nervous system functioning. Thus, defining whether antidepressants are harmful to astrocytes is an intriguing issue. We used an astrocyte cell line, primary cultured astrocytes and neuron cells, to identify the effects of 11 antidepressants which included selective serotonin reuptake inhibitors, a serotonin-norepinephrine reuptake inhibitor, tricyclic antidepressants, a tetracyclic antidepressant, a monoamine oxide inhibitor, and a serotonin antagonist and reuptake inhibitor. We found that treatment with 10 μM sertraline and 20 μM paroxetine significantly reduced cell viability. We further explored the underlying mechanisms and found induction of the [Ca²⁺]_i level in astrocytes. We also revealed that sertraline and paroxetine induced mitochondrial damage, ROS generation, and astrocyte apoptosis with elevation of cleaved-caspase 3 and cleaved-PARP levels. Ultimately, we validated these mechanisms in primary cultured astrocytes and neuron cells and obtained consistent results. These results suggest that sertraline and paroxetine cause astrocyte dysfunction, and this impairment may be involved in the pathogenesis of neurodegenerative diseases.

A Comparative Study of Three Different Types of Stem Cells for Treatment of Rat Spinal Cord Injury

Three different sources of human stem cells-bone marrow-derived mesenchymal stem cells (BM-MSCs), neural progenitors (NPs) derived from immortalized spinal fetal cell line (SPC-01), and induced pluripotent stem cells (iPSCs)-were compared in the treatment of a balloon-induced spinal cord compression lesion in rats. One week after lesioning, the rats received either BM-MSCs (intrathecally) or NPs (SPC-01 cells or iPSC-NPs, both intraspinally), or saline. The rats were assessed for their locomotor skills (BBB, flat beam test, and rotarod). Morphometric analyses of spared white and gray matter, axonal sprouting, and glial scar formation, as well as qPCR and Luminex assay, were conducted to detect endogenous gene expression, while inflammatory cytokine levels were performed to evaluate the host tissue response to stem cell therapy. The highest locomotor recovery was observed in iPSC-NP-grafted animals, which also displayed the highest amount of preserved white and gray matter. Grafted iPSC-NPs and SPC-01 cells significantly increased the number of growth-associated protein 43 (GAP43+) axons, reduced astrogliosis, downregulated Casp3 expression, and increased IL-6 and IL-12 levels. hMSCs transiently decreased levels of inflammatory IL-2 and TNF-α. These findings correlate with the short survival of hMSCs, while NPs survived for 2 months and matured slowly into glia- and tissue-specific neuronal precursors. SPC-01 cells differentiated more in astroglial phenotypes with a dense structure of the implant, whereas iPSC-NPs displayed a more neuronal phenotype with a loose structure of the graft. We concluded that the BBB scores of iPSC-NP- and hMSC-injected rats were superior to the SPC-01-treated group. The iPSC-NP treatment of spinal cord injury (SCI) provided the highest recovery of locomotor function due to robust graft survival and its effect on tissue sparing, reduction of glial scarring, and increased axonal sprouting.

Fluoxetine, an antidepressant, suppresses glioblastoma by evoking AMPAR-mediated calcium-dependent apoptosis

The efficacy of glioblastoma chemotherapy is not satisfactory; therefore, a new medication is expected to improve outcomes. As much evidence shows that antidepressants decrease cancer incidence and improve patients' quality of life, we therefore attempted to explore the potential for fluoxetine to be used to treat GBM and its possible underlying mechanism. The expression level of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) was determined using immunohistochemical staining and PCR analysis. The mechanism of fluoxetine-induced apoptosis of gliomas was elucidated. Computer modeling and a binding assay were conducted to investigate the interaction of fluoxetine with the AMPAR. The therapeutic effect of fluoxetine was evaluated using an animal model. We found that fluoxetine directly bound to AMPAR, thus inducing transmembrane Ca²⁺ influx. The rise in the intracellular calcium concentration ([Ca²⁺]_i) causes mitochondrial Ca²⁺ overload, thereby triggering apoptosis. AMPARs are excessively expressed in glioma tissues, suggesting that fluoxetine specifically executes glioma cells. Our in vivo study revealed that fluoxetine suppressed the growth of glioblastomas in brains of Nu/Nu mice, an effect similar to that produced by temozolomide. Our preclinical studies suggest fluoxetine, a commonly used antidepressant, might be selectively toxic to gliomas and could provide a new approach for managing this disease.

Curcumin Attenuates Inflammation, Oxidative Stress, and Ultrastructural Damage Induced by Spinal Cord Ischemia-Reperfusion Injury in Rats

OBJECTIVES

Curcumin is a molecule found in turmeric root that possesses anti-inflammatory and antioxidant properties and has been widely used to treat neurodegenerative diseases. We investigated whether curcumin stimulates the neurorepair process and improves locomotor function in a rat model of spinal cord ischemia-reperfusion injury.

METHODS

Thirty-two Wistar albino rats (190-220 g) were randomly allocated into 4 groups of 8 rats each: 1 sham-operated group and 3 ischemia-reperfusion injury groups that received intraperitoneal injections of saline vehicle, methylprednisolone (MP, 30 mg/kg following induction of ischemia-reperfusion [IR] injury), or curcumin (200 mg/kg for 7 days before induction of IR injury). Spinal cord IR injury was induced by occlusion of the abdominal aorta for 30 minutes. After 24 hours of reperfusion, locomotor function was assessed using the Basso, Beattie, and Bresnahan scale. All animals were sacrificed. Spinal cord tissues were harvested to evaluate histopathological and ultrastructural alterations and to analyze levels of malondialdehyde, tumor necrosis factor-alpha, interleukin-1 beta, nitric oxide, and caspase-3, as well as enzyme activities of superoxide dismutase and glutathione peroxidase.

RESULTS

Intraperitoneal administration of curcumin significantly reduced inflammatory cytokine expression, attenuated oxidative stress and lipid peroxidation, prevented apoptosis, and increased antioxidant defense mechanism activity in comparison to treatment with MP or saline. Histopathological and ultrastructural abnormalities were significantly reduced in curcumin-treated rats compared to the MP- and saline-treated groups. Furthermore, curcumin significantly improved locomotor function.

CONCLUSIONS

Curcumin treatment preserves neuronal viability against inflammation, oxidative stress, and apoptosis associated with ischemia-reperfusion injury.

CISD2 serves a novel role as a suppressor of nitric oxide signalling and curcumin increases CISD2 expression in spinal cord injuries

BACKGROUND

CISD2 is known to have roles in calcium metabolism, anti-apoptosis, and longevity. However, whether CISD2 is involved in the inflammatory response associated with injuries of the central nervous system (CNS) remains unclear. This issue is particularly relevant for traumatic spinal cord injuries (SCIs), which lack therapeutic targeting and often cause long-term disability in patients. The authors previously demonstrated the neuroprotective effects of curcumin against RANTES-mediated neuroinflammation. In this study, we investigated (1) the role of CISD2 in injury-induced inflammation and (2) whether curcumin influences CISD2 expression in acute SCI.

MATERIALS AND METHODS

The efficacy of curcumin treatment (40 mg/kg i.p.) was evaluated in an animal model of SCI. In a neural cell culture model, lipopolysaccharide (LPS) was administrated to induce inflammation with the aim of mimicking the situation commonly encountered in SCI. Additionally, knockdown of CISD2 expression by siRNA (siCISD2) in LPS-challenged neural cells was performed to verify the causal relationship between CISD2 and SCI-related inflammation.

RESULTS

The injuries were shown to reduce CISD2 mRNA and protein expression in vivo, and CISD2-positive cells were upregulated by the curcumin treatment. LPS led to a decrease in CISD2 expression in vitro; however, treatment with 1 μM curcumin attenuated the downregulation of CISD2. Furthermore, in a cellular model of LPS-induced injury, the loss of CISD2 function caused by siCISD2 resulted in a pronounced iNOS increase as well as a decrease in BCL2 expression.

CONCLUSIONS

To the best of our knowledge, this is the first study to report the following: (1) CISD2 exerts anti-apoptotic and anti-inflammatory effects in neural cells; and (2) curcumin can attenuate the downregulation of CISD2 in SCI and LPS-treated astrocytes.

Neurological recovery and antioxidant effects of curcumin for spinal cord injury in the rat: a network meta-analysis and systematic review

Spinal cord injury (SCI) is a devastating condition affecting young, healthy individuals worldwide. Existing agents have inadequate therapeutic efficacy, and some are associated with side effects. Our objective is to summarize and critically assess the neurological recovery and antioxidant effects of curcumin for treatment of SCI in rat models. PubMed, Embase, and Chinese databases were searched from their inception date to February 2014. Two reviewers independently selected animal studies that evaluated neurological recovery and antioxidant effects of curcumin, compared to placebo, in rats with SCI, extracted data, and assessed the methodological quality. A pair-wise analysis and a network meta-analysis were performed. Eight studies with adequate randomization were selected and included in the systematic review. Two studies had a higher methodological quality. Overall, curcumin appears to significantly improve neurological function, as assessed using the Basso, Beattie, Bresnahan (BBB) locomotor rating scale (four studies, n=132; pooled mean difference [MD]=3.09; 95% confidence interval [CI], 3.40-4.45; p=0.04), in a random-effects model and decrease malondialdehyde (MDA) using a fixed-effects model (four studies, n=56; pooled MD=-1.00; 95% CI=-1.59 to -0.42; p=0.00008). Effect size, assessed using the BBB scale, increased gradually with increasing curcumin dosage. The difference between low- and high-dose curcumin using the BBB scale was statistically significant. Neurological recovery and antioxidant effects of curcumin were observed in rats with SCI despite poor study methodological quality.

Natural polyphenols and spinal cord injury

Polyphenols have been shown to have some of the neuroprotective effects against neurodegenerative diseases. These effects are attributed to a variety of biological activities, including free radical scavenging/antioxidant and anti-inflammatory and anti-apoptotic activities. In this regard, many efforts have been made to study the effects of various well-known dietary polyphenols on spinal cord injury (SCI) and to explore the mechanisms behind the neuroprotective effects. The aim of this paper is to present the mechanisms of neuroprotection of natural polyphenols used in animal models of SCI.

Silibinin ameliorates LPS-induced memory deficits in experimental animals

Neuroinflammation is considered as one of the predisposing factor in the etiology of several neurodegenerative disorders. Therefore, the objective of the present study was to evaluate the protective effect of silibinin (SIL) in the lipopolysaccharide (LPS)-induced neuroinflammatory model. The effect of SIL on memory function was also evaluated on normal rats without LPS administration. In the first experiment, male rats were divided into five groups. Except control group animals, all rats received bilateral intracerebroventricular injection of LPS (5 μg/5 μl) into lateral ventricles on the first day of the experimental schedule. Control rats received bilateral intracerebroventricular injection of artificial cerebrospinal fluid into lateral ventricles. SIL in doses of 50, 100 and 200 mg/kg, p.o. was administered 1h before LPS injection and continued for 7 days. On Day-7, SIL attenuated the LPS-induced long-term and working memory loss in elevated plus and Y-maze test respectively. Further, SIL dose-dependently attenuated LPS-induced decrease in acetylcholine level and increase in the acetylcholinestrase activity in hippocampus and pre-frontal cortex. SIL ameliorated LPS-induced decrease in the mitochondrial complex activity (I, IV and V) and integrity, increase in lipid peroxidation and decrease in the activity of superoxide dismutase in both the brain regions. SIL attenuated amyloidogenesis in the hippocampus, while it decreased the LPS-induced increase in the level of NFκB in the pre-frontal cortex. In another study, SIL dose-dependently, enhanced memory functions in the normal rats, indicating its nootropic activity. Hence, SIL could be a potential candidate in the management of neuroinflammation-related memory disorders.

Curcumin improves the recovery of motor function and reduces spinal cord edema in a rat acute spinal cord injury model by inhibiting the JAK/STAT signaling pathway

Curcumin, a yellow pigment extracted from Carcuma longa, has been demonstrated to have extensive pharmacological activity in various studies, and it exhibits protective effects on injuries involving a number of human organs. The present study was designed to evaluate the potential effect and underlying mechanism of curcumin on the motor function and spinal cord edema in a rat acute spinal cord injury (SCI) model. The SCI model was induced by a heavy object falling. At 30min after the SCI was successfully induced, the animals were intraperitoneally given 40mg/kg curcumin. The Basso, Beattie and Bresnahan scores showed that curcumin moderately improved the recovery of the motor function in the injured rats, and hematoxylin-eosin staining demonstrated the role of this compound in reducing the hemorrhage, edema and neutrophil infiltration of the traumatic spinal cord. Furthermore, curcumin also inhibited the SCI-associated aquaporin - 4 (AQP4) overexpression and glial fibrillary acidic protein (GFAP) and repressed the unusual activation of the JAK/STAT signaling pathway. In conclusion, our data demonstrate that curcumin exhibits a moderately protective effect on spinal cord injury, and this effect might be related to the inhibition of overexpressed AQP4 and GFAP and the activated JAK/STAT signaling pathway. Curcumin may have potential for use as a therapeutic option for spinal cord injuries.

Curcumin improves the integrity of blood-spinal cord barrier after compressive spinal cord injury in rats

Previous studies have shown that curcumin (Cur) can produce potent neuroprotective effects against damage due to spinal cord injury (SCI). However, whether Cur can preserve the function of the blood-spinal cord barrier (BSCB) is unclear. The present study was performed to investigate the mechanism underlying BSCB permeability changes, which were induced by treatment with Cur (75, 150, and 300 mg/kg, i.p.) after compressive SCI in rats. BSCB permeability was evaluated by Evans blue leakage. Motor recovery of rats with SCI was assessed using the Basso, Beattie, and Bresnahan scoring system every day until the 21st days post-injury. The protein levels of heme oxygenase-1 (HO-1), tight junction protein, and inflammatory factors were analyzed by western blots. The expression of the inflammatory factors tumor necrosis factor-α (TNF-α) and nuclear factor-kappaB (NF-κB) mRNA was determined with reverse transcription-polymerase chain reactions. Treatment with Cur (150 and 300 mg/kg) significantly reduced Evans blue leakage into the spinal cord tissue at 24h after SCI. Cur (150 mg/kg) significantly increased HO-1 protein expression. The levels of TNF-α and NF-κB mRNA and protein greatly increased at 24h after SCI, and this increase was significantly attenuated by Cur treatment. ZO-1 and occludin expression was upregulated by Cur (150 mg/kg) treatment after SCI, and this effect was blocked by the HO-1 inhibitor zinc protoporphyrin. Long-term effects of Cur on motor recovery after SCI were observed. Our results indicated that Cur can improve motor function after SCI, which could correlate with improvements in BSCB integrity.

Effects of curcumin on acute spinal cord ischemia-reperfusion injury in rabbits

Object

The object of this study was to conduct a prospective, randomized, laboratory investigation of the neuroprotective effects of curcumin functionally, biochemically, and histologically in an experimental acute spinal cord ischemia-reperfusion injury on rabbits.

Methods

Eighteen rabbits were randomly assigned to 1 of 3 groups: the sham group, the ischemia-reperfusion group, or the curcumin group. Spinal cord ischemia was induced by applying an infrarenal aortic cross-clamp for 30 minutes. At 48 hours after ischemia, neurological function was evaluated with modified Tarlov criteria. Biochemical changes in the spinal cord and plasma were observed by measuring levels of malondialdehyde (MDA), advanced oxidation protein products (AOPP), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), nitrite/nitrate, and tumor necrosis factor-α (TNF-α). Histological changes were examined with H & E staining. Immunohistochemical staining with antibodies against caspase-3 was performed to evaluate cell apoptosis after ischemia.

Results

In the curcumin group, neurological outcome scores were statistically significantly better compared with the ischemia-reperfusion group. In the ischemia-reperfusion group, MDA, AOPP, and nitrite/nitrate levels were significantly elevated in the spinal cord tissue and the plasma by the induction of ischemia-reperfusion. The curcumin treatment significantly prevented the ischemia-reperfusion–induced elevation of nitrite/nitrate and TNF-α. In addition, the spinal cord tissue and the plasma SOD, GSH, and CAT levels were found to be preserved in the curcumin group and not statistically different from those of the sham group. Histological evaluation of the tissues also demonstrated a decrease in axonal damage, neuronal degeneration, and glial cell infiltration after curcumin administration.

Conclusions

Although further studies including different dose regimens and time intervals are required, curcumin could attenuate a spinal cord ischemia-reperfusion injury in rabbits via reducing oxidative products and proinflammatory cytokines, as well as increasing activities of antioxidant enzymes and preventing apoptotic cell death.

Stem cell therapy and curcumin synergistically enhance recovery from spinal cord injury

Acute traumatic spinal cord injury (SCI) is marked by the enhanced production of local cytokines and pro-inflammatory substances that induce gliosis and prevent reinnervation. The transplantation of stem cells is a promising treatment strategy for SCI. In order to facilitate functional recovery, we employed stem cell therapy alone or in combination with curcumin, a naturally-occurring anti-inflammatory component of turmeric (Curcuma longa), which potently inhibits NF-κB. Spinal cord contusion following laminectomy (T9–10) was performed using a weight drop apparatus (10 g over a 12.5 or 25 mm distance, representing moderate or severe SCI, respectively) in Sprague-Dawley rats. Neural stem cells (NSC) were isolated from subventricular zone (SVZ) and transplanted at the site of injury with or without curcumin treatment. Functional recovery was assessed by BBB score and body weight gain measured up to 6 weeks following SCI. At the conclusion of the study, the mass of soleus muscle was correlated with BBB score and body weight. Stem cell therapy improved recovery from moderate SCI, however, it had a limited effect on recovery after severe SCI. Curcumin stimulated NSC proliferation in vitro, and in combination with stem cell therapy, induced profound recovery from severe SCI as evidenced by improved functional locomotor recovery, increased body weight, and soleus muscle mass. These findings demonstrate that curcumin in conjunction with stem cell therapy synergistically improves recovery from severe SCI. Furthermore, our results indicate that the effect of curcumin extends beyond its known anti-inflammatory properties to the regulation of stem cell proliferation.

Antiepileptogenic effect of curcumin on kainate-induced model of temporal lobe epilepsy

CONTEXT

Temporal lobe epilepsy (TLE) is an intractable neurological disorder. Curcumin is the bioactive component of turmeric with anti-epileptic and neuroprotective potential.

OBJECTIVE

The beneficial effect of curcumin on the intrahippocampal kainate-induced model of TLE was investigated.

MATERIALS AND METHODS

Rats were divided into sham, curcumin-pretreated sham, kainate and curcumin-pretreated kainate groups. The rat model of TLE was induced by unilateral intrahippocampal injection of 4 μg of kainate. Rats received curcumin p.o. at a dose of 100 mg/kg/d starting 1 week before the surgery. Seizure activity (SE) and oxidative stress-related markers were measured. Furthermore, the Timm index for evaluation of mossy fiber sprouting (MFS) and number of Nissl-stained neurons were quantified.

RESULTS

All rats in the kainate group had SE, while 28.5% of rats showed seizures in the curcumin-pretreated kainate group. Malondialdehyde and nitrite and nitrate levels significantly increased in the kainate group (p < 0.01 and p < 0.05, respectively), and curcumin significantly lowered these parameters (p < 0.05). Superoxide dismutase activity significantly decreased in the kainate group (p < 0.05) and curcumin did not improve it. Rats in the kainate group showed a significant reduction of neurons in Cornu Ammonis 1 (CA1) (p < 0.05), CA3 (p < 0.005) and hilar (p < 0.01) regions, and curcumin significantly prevented these changes (p < 0.05-0.005). The Timm index significantly increased in the kainate group (p < 0.005), and curcumin significantly lowered this index (p < 0.01).

DISCUSSION AND CONCLUSION

Curcumin pretreatment can attenuate seizures, lower some oxidative stress markers, and prevent hippocampal neuronal loss and MFS in the kainate-induced model of TLE.

Cell type-specific dependency on the PI3K/Akt signaling pathway for the endogenous Epo and VEGF induction by baicalein in neurons versus astrocytes

The neuroprotective effect of baicalein is generally attributed to inhibition of 12/15-lipoxygenase (12/15-LOX) and suppression of oxidative stress, but recent studies showed that baicalein also activates hypoxia-inducible factor-α (HIF1α) through inhibition of prolyl hydrolase 2 (PHD2) and activation of the phosphatidylinositide-3 kinase (PI3K)/Akt signaling pathway. Yet, the significance and regulation of prosurvival cytokines erythropoietin (Epo) and vascular endothelial growth factor (VEGF), two transcriptional targets of HIF1α, in baicalein-mediated neuroprotection in neurons and astrocytes remains unknown. Here we investigated the causal relationship between the PI3K/Akt signaling pathway and Epo/VEGF expression in baicalein-mediated neuroprotection in primary rat cortical neurons and astrocytes. Our results show that baicalein induced Epo and VEGF expression in a HIF1α- and PI3K/Akt-dependent manner in neurons. Baicalein also protected neurons against excitotoxicity in a PI3K- and Epo/VEGF-dependent manner without affecting neuronal excitability. In contrast, at least a 10-fold higher concentration of baicalein was needed to induce Epo/VEGF production and PI3K/Akt activity in astrocytes for protection of neurons. Moreover, only baicalein-induced astrocytic VEGF, but not Epo expression requires HIF1α, while PI3K/Akt signaling had little role in baicalein-induced astrocytic Epo/VEGF expression. These results suggest distinct mechanisms of baicalein-mediated Epo/VEGF production in neurons and astrocytes for neuroprotection, and provide new insights into the mechanisms and potential of baicalein in treating brain injury in vivo.

Mechanisms of dendritic cell trafficking across the blood-brain barrier

Although the central nervous system (CNS) is considered to be an immunoprivileged site, it is susceptible to a host of autoimmune as well as neuroinflammatory disorders owing to recruitment of immune cells across the blood-brain barrier into perivascular and parenchymal spaces. Dendritic cells (DCs), which are involved in both primary and secondary immune responses, are the most potent immune cells in terms of antigen uptake and processing as well as presentation to T cells. In light of the emerging importance of DC traficking into the CNS, these cells represent good candidates for targeted immunotherapy against various neuroinflammatory diseases. This review focuses on potential physiological events and receptor interactions between DCs and the microvascular endothelial cells of the brain as they transmigrate into the CNS during degeneration and injury. A clear understanding of the underlying mechanisms involved in DC migration may advance the development of new therapies that manipulate these mechanistic properties via pharmacologic intervention. Furthermore, therapeutic validation should be in concurrence with the molecular imaging techniques that can detect migration of these cells in vivo. Since the use of noninvasive methods to image migration of DCs into CNS has barely been explored, we highlighted potential molecular imaging techniques to achieve this goal. Overall, information provided will bring this important leukocyte population to the forefront as key players in the immune cascade in the light of the emerging contribution of DCs to CNS health and disease.

Recovery from spinal cord injury using naturally occurring antiinflammatory compound curcumin: laboratory investigation

OBJECT

Spinal cord injury (SCI) is a debilitating disease. Primary SCI results from direct injury to the spinal cord, whereas secondary injury is a side effect from subsequent edema and ischemia followed by activation of proinflammatory cytokines. These cytokines activate the prosurvival molecule nuclear factor-κB and generate obstacles in spinal cord reinnervation due to gliosis. Curcumin longa is an active compound found in turmeric, which acts as an antiinflammatory agent primarily by inhibiting nuclear factor-κB. Here, the authors study the effect of curcumin on SCI recovery.

METHODS

Fourteen female Sprague-Dawley rats underwent T9-10 laminectomy and spinal cord contusion using a weight-drop apparatus. Within 30 minutes after contusion and weekly thereafter, curcumin (60 mg/kg/ml body weight in dimethyl sulfoxide) or dimethyl sulfoxide (1 ml/kg body weight) was administered via percutaneous epidural injection at the injury site. Spinal cord injury recovery was assessed weekly by scoring hindlimb motor function. Animals were killed 6 weeks postcontusion for histopathological analysis of spinal cords and soleus muscle weight evaluation.

RESULTS

Curcumin-treated rats had improved motor function compared with controls starting from Week 1. Body weight gain significantly improved, correlating with improved Basso-Beattie-Bresnahan scores. Soleus muscle weight was greater in curcumin-treated rats than controls. Histopathological analysis validated these results with increased neural element mass with less gliosis at the contusion site in curcumin-treated rats than controls.

CONCLUSIONS

Epidural administration of curcumin resulted in improved recovery from SCI. This occurred with no adverse effects noted in experimental animals. Therefore, curcumin treatment may translate into a novel therapy for humans with SCI.