Bee venom phospholipase A2 ameliorates motor dysfunction and modulates microglia activation in Parkinson's disease alpha-synuclein transgenic mice

Toxin-derived peptides: An unconventional approach to alleviating cerebral stroke burden and neurobehavioral impairments

Cerebral stroke is a pressing global health concern, ranking as the second leading cause of mortality and resulting in persistent neurobehavioral impairments. Cerebral strokes, triggered by various embolic events, initiate complex signaling pathways involving neuroexcitotoxicity, ionic imbalances, inflammation, oxidative stress, acidosis, and mitochondrial dysfunction, leading to programmed cell death. Currently, the FDA has approved tissue plasminogen activator as a relatively benign intervention for cerebral stroke, leaving a significant treatment gap. However, a promising avenue has emerged from Earth's toxic creatures. Animal venoms harbor bioactive molecules, particularly neuropeptides, with potential in innovative healthcare applications. These venomous components, affecting ion channels, receptors, and transporters, encompass neurochemicals, amino acids, and peptides, making them prime candidates for treating cerebral ischemia and neurological disorders. This review explores the composition, applications, and significance of toxin-derived peptides as viable therapeutic agents. It also investigates diverse toxins from select venomous creatures, with the primary objective of shedding light on current stroke treatments and paving the way for pioneering therapeutic strategies capable of addressing neurobehavioral deficits.

Harnessing the power of bee venom for therapeutic and regenerative medical applications: an updated review

Honeybees have been helpful insects since ancient centuries, and this benefit is not limited to being a honey producer only. After the bee stings a person, pain, and swelling occur in this place, due to the effects of bee venom (BV). This is not a poison in the total sense of the word because it has many benefits, and this is due to its composition being rich in proteins, peptides, enzymes, and other types of molecules in low concentrations that show promise in the treatment of numerous diseases and conditions. BV has also demonstrated positive effects against various cancers, antimicrobial activity, and wound healing versus the human immunodeficiency virus (HIV). Even though topical BV therapy is used to varying degrees among countries, localized swelling or itching are common side effects that may occur in some patients. This review provides an in-depth analysis of the complex chemical composition of BV, highlighting the diverse range of bioactive compounds and their therapeutic applications, which extend beyond the well-known anti-inflammatory and pain-relieving effects, showcasing the versatility of BV in modern medicine. A specific search strategy was followed across various databases; Web of sciences, Scopus, Medline, and Google Scholar including in vitro and in vivo clinical studies.to outline an overview of BV composition, methods to use, preparation requirements, and Individual consumption contraindications. Furthermore, this review addresses safety concerns and emerging approaches, such as the use of nanoparticles, to mitigate adverse effects, demonstrating a balanced and holistic perspective. Importantly, the review also incorporates historical context and traditional uses, as well as a unique focus on veterinary applications, setting it apart from previous works and providing a valuable resource for researchers and practitioners in the field.

Bee venom as a promising therapeutic strategy in central nervous system diseases

Central nervous system (CNS) disorders are one of the leading health problems today, accounting for a large proportion of global morbidity and mortality. Most these disorders are characterized by high levels of oxidative stress and intense inflammatory responses in degenerated neuronal tissues. While extensive research has been conducted on CNS diseases, but few breakthroughs have been made in treatment methods. To date, there are no disease-modifying drugs available for CNS treatment, underscoring the urgent need for finding effective medications. Bee venom (BV), which is produced by honeybee workers' stingers, has been a subject of interest and study across various cultures. Over the past few decades, extensive research has focused on BV and its therapeutic potentials. BV consists a variety of substances, mainly proteins and peptides like melittin and phospholipase A2 (PLA2). Research has proven that BV is effective in various medical conditions, including pain, arthritis and inflammation and CNS disorders such as Multiple sclerosis, Alzheimer's disease and Parkinson's disease. This review provides a comprehensive overview of the existing knowledge concerning the therapeutic effects of BV and its primary compounds on various CNS diseases. Additionally, we aim to shed light on the potential cellular and molecular mechanisms underlying these effects.

The Potentiality of Natural Products and Herbal Medicine as Novel Medications for Parkinson's Disease: A Promising Therapeutic Approach

As the global population ages, the prevalence of Parkinson's disease (PD) is steadily on the rise. PD demonstrates chronic and progressive characteristics, and many cases can transition into dementia. This increases societal and economic burdens, emphasizing the need to find effective treatments. Among the widely recognized causes of PD is the abnormal accumulation of proteins, and autophagy dysfunction accelerates this accumulation. The resultant Lewy bodies are also commonly found in Alzheimer's disease patients, suggesting an increased potential for the onset of dementia. Additionally, the production of free radicals due to mitochondrial dysfunction contributes to neuronal damage and degeneration. The activation of astrocytes and the M1 phenotype of microglia promote damage to dopamine neurons. The drugs currently used for PD only delay the clinical progression and exacerbation of the disease without targeting its root cause, and come with various side effects. Thus, there is a demand for treatments with fewer side effects, with much potential offered by natural products. In this study, we reviewed a total of 14 articles related to herbal medicines and natural products and investigated their relevance to possible PD treatment. The results showed that the reviewed herbal medicines and natural products are effective against lysosomal disorder, mitochondrial dysfunction, and inflammation, key mechanisms underlying PD. Therefore, natural products and herbal medicines can reduce neurotoxicity and might improve both motor and non-motor symptoms associated with PD. Furthermore, these products, with their multi-target effects, enhance bioavailability, inhibit antibiotic resistance, and might additionally eliminate side effects, making them good alternative therapies for PD treatment.

Protease-Sensitive and -Resistant Forms of Human and Murine Alpha-Synucleins in Distinct Brain Regions of Transgenic Mice (M83) Expressing the Human Mutated A53T Protein

Human neurodegenerative diseases associated with the misfolding of the alpha-synuclein (aS) protein (synucleinopathies) are similar to prion diseases to the extent that lesions are spread by similar molecular mechanisms. In a transgenic mouse model (M83) overexpressing a mutated (A53T) form of human aS, we had previously found that Protein Misfolding Cyclic Amplification (PMCA) triggered the aggregation of aS, which is associated with a high resistance to the proteinase K (PK) digestion of both human and murine aS, a major hallmark of the disease-associated prion protein. In addition, PMCA was also able to trigger the aggregation of murine aS in C57Bl/6 mouse brains after seeding with sick M83 mouse brains. Here, we show that intracerebral inoculations of M83 mice with C57Bl/6-PMCA samples strikingly shortens the incubation period before the typical paralysis that develops in this transgenic model, demonstrating the pathogenicity of PMCA-aggregated murine aS. In the hind brain regions of these sick M83 mice containing lesions with an accumulation of aS phosphorylated at serine 129, aS also showed a high PK resistance in the N-terminal part of the protein. In contrast to M83 mice, old APPxM83 mice co-expressing human mutated amyloid precursor and presenilin 1 proteins were seen to have an aggregation of aS, especially in the cerebral cortex, hippocampus and striatum, which also contained the highest load of aS phosphorylated at serine 129. This was proven by three techniques: a Western blot analysis of PK-resistant aS; an ELISA detection of aS aggregates; or the identification of aggregates of aS using immunohistochemical analyses of cytoplasmic/neuritic aS deposits. The results obtained with the D37A6 antibody suggest a higher involvement of murine aS in APPxM83 mice than in M83 mice. Our study used novel tools for the molecular study of synucleinopathies, which highlight similarities with the molecular mechanisms involved in prion diseases.

Screening of H2S donors with a red emission mitochondria-targetable fluorescent probe: Toward discovering a new therapeutic strategy for Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder caused by various factors such as neuroinflammation, oxidative stress, mitochondrial dysfunction, and neuronal apoptosis. Recent studies have shown that H2S supplementation reverses neuronal loss and mitigates motor deficits in PD patients through anti-inflammatory, antioxidant, improved mitochondrial function and proautophagic. Therefore, the discovery and use of H2S donors may be an exciting and intriguing strategy for the treatment of PD. Herein, we report a red emission mitochondria-targetable fluorescent probe, Rho-H2S, which can specifically and sensitively detect H2S with a limit of detection of 62.5 nM. Bioimaging experiments have shown that the probe has excellent mitochondrial targeting and good imaging capabilities for the detection of exogenous and endogenous H2S in cells. More importantly, based on the Rho-H2S probe, we first confirmed the sulforaphane (SFN) among 15 glucosinolate and isothiocyanate compounds from cruciferous vegetables with an outstanding ability to release H2S and we further proved that SFN could alleviate the symptoms of PD in vivo. All results demonstrate that Rho-H2S could be an effective tool for screening H2S donors and can contribute to the development of new therapeutic strategies for PD.

RNA- and ATAC-sequencing Reveals a Unique CD83+ Microglial Population Focally Depleted in Parkinson's Disease

All brain areas affected in Parkinson's disease (PD) show an abundance of microglia with an activated morphology together with increased expression of pro-inflammatory cytokines, suggesting that neuroinflammation may contribute to the neurodegenerative process in this common and incurable disorder. We applied a single nucleus RNA- and ATAC-sequencing approach using the 10x Genomics Chromium platform to postmortem PD samples to investigate microglial heterogeneity in PD. We created a multiomic dataset using substantia nigra (SN) tissues from 19 PD donors and 14 non-PD controls (NPCs), as well as three other brain regions from the PD donors which are differentially affected in this disease: the ventral tegmental area (VTA), substantia inominata (SI), and hypothalamus (HypoTs). We identified thirteen microglial subpopulations within these tissues as well as a perivascular macrophage and a monocyte population, of which we characterized the transcriptional and chromatin repertoires. Using this data, we investigated whether these microglial subpopulations have any association with PD and whether they have regional specificity. We uncovered several changes in microglial subpopulations in PD, which appear to parallel the magnitude of neurodegeneration across these four selected brain regions. Specifically, we identified that inflammatory microglia in PD are more prevalent in the SN and differentially express PD-associated markers. Our analysis revealed the depletion of a CD83 and HIF1A- expressing microglial subpopulation, specifically in the SN in PD, that has a unique chromatin signature compared to other microglial subpopulations. Interestingly, this microglial subpopulation has regional specificity to the brainstem in non-disease tissues. Furthermore, it is highly enriched for transcripts of proteins involved in antigen presentation and heat-shock proteins, and its depletion in the PD SN may have implications for neuronal vulnerability in disease.

Aurantiamide suppresses the activation of NLRP3 inflammasome to improve the cognitive function and central inflammation in mice with Alzheimer's disease

AIM

This study was aimed at exploring the mechanism by which aurantiamide (Aur) targeted NLRP3 to suppress microglial cell polarization.

METHODS

The 7-month-old APP/PS1 mice and C57BL/6 mice were applied to be the study objects, and Aur was administered intragastrically to APP/PS1 mice at 10 mg/kg and 20 mg/kg. The changes in the neurocognitive function of mice were measured by Morris Water Maze (MWM) test. In the in vitro experiments, the mouse BV2 cells were employed as the study objects, which were subject to treatment with 10 μM and 20 μM Aur and induced with LPS and IFN-γ in order to activate BV2 cells and induce their M1 polarization.

RESULTS

Aur was found to suppress the M1 polarization of mouse microglia, reduce central neuroinflammation, and improve the cognitive function in mice. Meanwhile, Aur suppressed the activation and the expression of NLRP3 inflammasome. The results of experiments in vitro demonstrated that Aur inhibited the activation and M1 polarization of BV2 cells.

CONCLUSION

Aur targets NLRP3 and suppresses the activation of NLRP3 inflammasome.

Therapeutic Potential of Bee and Scorpion Venom Phospholipase A2 (PLA2): A Narrative Review

Venomous arthropods such as scorpions and bees form one of the important groups with an essential role in medical entomology. Their venom possesses a mixture of diverse compounds, such as peptides, some of which have toxic effects, and enzymatic peptide Phospholipase A2 (PLA2) with a pharmacological potential in the treatment of a wide range of diseases. Bee and scorpion venom PLA2 group III has been used in immunotherapy, the treatment of neurodegenerative and inflammatory diseases. They were assessed for antinociceptive, wound healing, anti-cancer, anti-viral, anti-bacterial, anti-parasitic, and anti-angiogenesis effects. PLA2 has been identified in different species of scorpions and bees. The anti-leishmania, anti-bacterial, anti-viral, and anti-malarial activities of scorpion PLA2 still need further investigation. Many pieces of research have been stopped in the laboratory stage, and several studies need vast investigation in the clinical phase to show the pharmacological potential of PLA2. In this review, the medical significance of PLA2 from the venom of two arthropods, namely bees and scorpions, is discussed.

Microglia Polarization From M1 to M2 in Neurodegenerative Diseases

Microglia-mediated neuroinflammation is a common feature of neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). Microglia can be categorized into two opposite types: classical (M1) or alternative (M2), though there’s a continuum of different intermediate phenotypes between M1 and M2, and microglia can transit from one phenotype to another. M1 microglia release inflammatory mediators and induce inflammation and neurotoxicity, while M2 microglia release anti-inflammatory mediators and induce anti-inflammatory and neuroprotectivity. Microglia-mediated neuroinflammation is considered as a double-edged sword, performing both harmful and helpful effects in neurodegenerative diseases. Previous studies showed that balancing microglia M1/M2 polarization had a promising therapeutic prospect in neurodegenerative diseases. We suggest that shifting microglia from M1 to M2 may be significant and we focus on the modulation of microglia polarization from M1 to M2, especially by important signal pathways, in neurodegenerative diseases.

The Responsiveness of Bee Venom Phospholipase A2 on Regulatory T Cells Correlates with the CD11c+CD206+Population in Human Peripheral Blood Mononuclear Cells

Bee venom phospholipase A2 (bvPLA2) has been reported to have therapeutic effects such as neuroprotection, anti-inflammation, anti-nociception, anti-cancer properties, caused by increasing regulatory T cells (Tregs). The mechanism of Tregs modulation by bvPLA2 has been demonstrated by binding with the mannose receptor, CD206 in experimental models of several diseases. However, it remains unknown whether this mechanism can also be applied in human blood. In this study, we collected peripheral blood samples from healthy donors and analyzed the percentages of monocyte-derived dendritic cells with CD206 (CD206⁺ DCs) before expansion, the proportion of Tregs, and the subpopulations after expansion treated with bvPLA2 or PBS using flow cytometry and the correlations among them. The percentage of Tregs tended to be higher in the bvPLA2 group than in the control group. There were significant positive correlations between the CD206 population in hPBMC and the proportions of Tregs treated with bvPLA2, especially in the Treg fold change comparing the increase ratio of Tregs in bvPLA2 and in PBS. These findings indicate that bvPLA2 increased the proportion of Tregs in healthy human peripheral blood and the number of CD206⁺ DCs could be a predictor of the bvPLA2 response of different individuals.

Bee venom attenuates neurodegeneration and motor impairment and modulates the response to L-dopa or rasagiline in a mice model of Parkinson's disease

Objectives

This study aimed to investigate the effect of bee venom, a form of alternative therapy, on rotenone-induced Parkinson's disease (PD) in mice. Moreover, the possible modulation by bee venom of the effect of L-dopa/carbidopa or rasagiline was examined.

Materials and Methods

Rotenone (1.5 mg/kg, subcutaneously; SC) was administered every other day for two weeks and at the same time mice received the vehicle (DMSO, SC), bee venom (0.065, 0.13, and 0.26 mg/kg; intradermal; ID), L-dopa/carbidopa (25 mg/kg, intraperitoneal; IP), L-dopa/carbidopa+bee venom (0.13 mg/kg, ID), rasagiline (1 mg/kg, IP) or rasagiline+bee venom (0.13 mg/kg, ID). Then, wire hanging and staircase tests were performed and mice were euthanized and brains' striata separated. Oxidative stress biomarkers namely, malondialdehyde (MDA), nitric oxide (NO), reduced glutathione (GSH), paraoxonase-1 (PON-1), and total antioxidant capacity (TAC) were measured. Additionally, butyrylcholinesterase (BuChE), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), and dopamine (DA) were evaluated. Brain histopathological changes and caspase-3- expression were done.

Results

Bee venom significantly enhanced motor performance and inhibited rotenone-induced oxidative/nitrosative stress, observed as a reduction in both MDA and NO along with increasing GSH, PON-1, and TAC. Besides, bee venom decreased MCP-1, TNF-α, and caspase-3 expression together with an increase in BuChE activity and DA content.

Conclusion

Bee venom alone or in combination with L-dopa/carbidopa or rasagiline alleviated neuronal degeneration compared with L-dopa/carbidopa or rasagiline treatment only. Bee venom via its antioxidant and cytokine reducing potentials might be of value either alone or as adjunctive therapy in the management of PD.

Venoms as an adjunctive therapy for Parkinson's disease: where are we now and where are we going?

Neurodegenerative diseases, including Parkinson's disease (PD), are increasing in the aging population. Crucially, neurodegeneration of dopaminergic neurons in PD is associated with chronic inflammation and glial activation. Besides this, bradykinesia, resting tremor, rigidity, sensory alteration, and cognitive and psychiatric impairments are also present in PD. Currently, no pharmacologically effective treatment alters the progression of the disease. Discovery and development of new treatment strategies remains a focus for ongoing investigations. For example, one approach is cell therapy to prevent dopaminergic neuronal loss or to slow PD progression. The neuroprotective role of a diverse range of natural products, including venoms from bees, scorpions, snakes and lizards, are also being tested in preclinical PD models and in humans. The main findings from recent studies that have investigated venoms as therapeutic options for PD are summarized in this special report.

Bee Venom: An Updating Review of Its Bioactive Molecules and Its Health Applications

Bee venom (BV) is usually associated with pain since, when humans are stung by bees, local inflammation and even an allergic reaction can be produced. BV has been traditionally used in ancient medicine and in acupuncture. It consists of a mixture of substances, principally of proteins and peptides, including enzymes as well as other types of molecules in a very low concentration. Melittin and phospholipase A2 (PLA2) are the most abundant and studied compounds of BV. Literature of the main biological activities exerted by BV shows that most studies focuses on the comprehension and test of anti-inflammatory effects and its mechanisms of action. Other properties such as antioxidant, antimicrobial, neuroprotective or antitumor effects have also been assessed, both in vitro and in vivo. Moreover, human trials are necessary to confirm those clinical applications. However, notwithstanding the therapeutic potential of BV, there are certain problems regarding its safety and the possible appearance of adverse effects. On this perspective, new approaches have been developed to avoid these complications. This manuscript is aimed at reviewing the actual knowledge on BV components and its associated biological activities as well as the latest advances on this subject.

Apitherapy for Parkinson's Disease: A Focus on the Effects of Propolis and Royal Jelly

The vast increase of world's aging populations is associated with increased risk of age-related neurodegenerative diseases such as Parkinson's disease (PD). PD is a widespread disorder characterized by progressive loss of dopaminergic neurons in the substantia nigra, which encompasses a wide range of debilitating motor, emotional, cognitive, and physical symptoms. PD threatens the quality of life of millions of patients and their families. Additionally, public welfare and healthcare systems are burdened with its high cost of care. Available treatments provide only a symptomatic relief and produce a trail of noxious side effects, which increase noncompliance. Hence, researchers have recently focused on the use of nutraceuticals as safe adjunctive treatments of PD to limit its progress and associated damages in affected groups. Propolis is a common product of the beehive, which possesses a large number of therapeutic properties. Royal jelly (RJ) is a bee product that is fed to bee queens during their entire life, and it contributes to their high physical fitness, fertility, and long lifespan. Evidence suggests that propolis and RJ can promote health by preventing the occurrence of age-related debilitating diseases. Therefore, they have been used to treat various serious disorders such as diabetes mellitus, cardiovascular diseases, and cancer. Some evolving studies used these bee products to treat PD in animal models. However, a clear understanding of the collective effect of propolis and RJ as well as their mechanism of action in PD is lacking. This review evaluates the available literature for the effects of propolis and RJ on PD. Whenever possible, it elaborates on the underlying mechanisms through which they function in this disorder and offers insights for fruitful use of bee products in future clinical trials.

Clinical Applications of Bee Venom Acupoint Injection

Bee venom is a complex natural mixture with various pharmaceutical properties. Among these properties, its peptides and enzymes have potential medical therapy for pain relief and inflammation. In clinical settings, this therapy has been used widely to treat diseases by injecting into acupoints. In this article, we have conducted various research from PubMed, Cochrane Library, and Clinical Key from inception of July 2020. The results revealed that bee venom therapy has been reported effective in anti-inflammatory, antiapoptosis, and analgesic effects. Moreover, bee venom acupuncture has been commonly used for clinical disorders such as Parkinson disease, neuropathic pain, Alzheimer disease, intervertebral disc disease, spinal cord injury, musculoskeletal pain, arthritis, multiple sclerosis, skin disease and cancer.

Changes in the cellular fatty acid profile drive the proteasomal degradation of α-synuclein and enhance neuronal survival

Parkinson's disease is biochemically characterized by the deposition of aberrant aggregated α-synuclein in the affected neurons. The aggregation properties of α-synuclein greatly depend on its affinity to bind cellular membranes via a dynamic interaction with specific lipid moieties. In particular, α-synuclein can interact with arachidonic acid (AA), a polyunsaturated fatty acid, in a manner that promotes the formation of α-helix enriched assemblies. In a cellular context, AA is released from membrane phospholipids by phospholipase A₂ (PLA₂ ). To investigate the impact of PLA₂ activity on α-synuclein aggregation, we have applied selective PLA₂ inhibitors to a SH-SY5Y cellular model where the expression of human wild-type α-synuclein is correlated with a gradual accumulation of soluble oligomers and subsequent cell death. We have found that pharmacological and genetic inhibition of GIVA cPLA₂ resulted in a dramatic decrease of intracellular oligomeric and monomeric α-synuclein significantly promoting cell survival. Our data suggest that alterations in the levels of free fatty acids, and especially AA and adrenic acid, promote the formation of α-synuclein conformers which are more susceptible to proteasomal degradation. This mechanism is active only in living cells and is generic since it does not depend on the absolute quantity of α-synuclein, the presence of disease-linked point mutations, the expression system or the type of cells. Our findings indicate that the α-synuclein-fatty acid interaction can be a critical determinant of the conformation and fate of α-synuclein in the cell interior and, as such, cPLA₂ inhibitors could serve to alleviate the intracellular, potentially pathological, α-synuclein burden.

Tetramethylpyrazine Analogue T-006 Promotes the Clearance of Alpha-synuclein by Enhancing Proteasome Activity in Parkinson's Disease Models

Parkinson's disease (PD) is the second most common neurodegenerative disorder worldwide and is characterized in part by the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc). The main pathological hallmark of PD is the intraneuronal accumulation of misfolded α-synuclein (α-syn) aggregates. Mutations in the SNCA gene (encoding α-syn) and variations in its copy number are associated with some forms of familial PD. In the present study, T-006, a new tetramethylpyrazine (TMP) derivative with recently reported anti-Alzheimer activity, is shown to significantly promote α-syn degradation in a cellular PD model. Moreover, we illustrate that T-006 inhibits the accumulation of both Triton-soluble and -insoluble forms of α-syn and protects against α-syn-induced neurotoxicity in A53T-α-syn transgenic mice. The mechanism of action of T-006 was verified by evaluation of a potential protein degradation pathway. We found that T-006 promotes α-syn degradation in a proteasome-dependent and autophagy-independent manner. We further confirmed that T-006 enhances proteasome activity by upregulating 20S proteasome subunit β5i (LMP7) protein expression. A functional study revealed that T-006 activates the PKA/Akt/mTOR/p70S6K pathway to trigger LMP7 expression and enhance chymotrypsin-like proteasomal activity. These findings indicate that T-006 is a potent proteasome activator and a potential therapeutic agent for the prevention and treatment of PD and related diseases.

Animal venoms: therapeutic tools for tackling Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative pathology of the central nervous system, mainly involving the selective and progressive loss of dopaminergic neurons from the substantia nigra, resulting in motor and non-motor symptoms. PD remains an incurable ailment; thus, treatments are limited to symptom alleviation. With long-term use, conventional treatments can become inefficient, often triggering possible side effects. Considering these drawbacks, drug discovery constantly turns to nature as a source of efficient therapeutics. Thus, this review explores animal venoms as a rich source of bioactive compounds with potent neuropharmacological profiles for the development of effective adjuvant treatments with fewer side effects, ultimately aiming for the neuroprotection of dopaminergic neurons and the symptomatic relief of PD.

Suppressive Effects of Bee Venom-Derived Phospholipase A2 on Mechanical Allodynia in a Rat Model of Neuropathic Pain

Bee venom (BV) has a long history of being used in traditional Korean medicine to relieve pain. Here, we investigated the effect of BV-derived phospholipase A2 (bvPLA2), a major component of BV, on peripheral nerve injury-induced neuropathic pain in rats. Spinal nerve ligation (SNL) was performed in Sprague Dawley rats to induce neuropathic pain, and paw withdrawal thresholds were measured using von Frey test. Mechanical allodynia, the representative symptom of neuropathic pain, was manifested following SNL and persisted for several weeks. The repetitive bvPLA2 treatment (0.2 mg/kg/day, i.p.) for two days significantly relieved the SNL-induced mechanical allodynia. The antiallodynic effect of bvPLA2 was blocked by spinal pretreatment with α1-adrenergic antagonist prazosin (30 μg, i.t.) but not with α2-adrenergic antagonist idazoxan (50 μg, i.t.). Also, the spinal application of α1-adrenergic agonist phenylephrine (50 μg, i.t.) reduced mechanical allodynia. These results indicate that bvPLA2 could relieve nerve injury-induced neuropathic mechanical allodynia through the activation of spinal α1-adrenergic receptors.

Kir6.1/K-ATP channel modulates microglia phenotypes: implication in Parkinson's disease

Classical activation (M1 phenotype) and alternative activation (M2 phenotype) are the two polars of microglial activation states that can produce either neurotoxic or neuroprotective effects in the immune pathogenesis of Parkinson’s disease (PD). Exploiting the beneficial properties of microglia cells by modulating their polarization states provides great potential for the treatment of PD. However, the mechanism that regulates microglia polarization remains elusive. Here we demonstrated that Kir6.1-containing ATP-sensitive potassium (Kir6.1/K-ATP) channel switched microglia from the detrimental M1 phenotype toward the beneficial M2 phenotype. Kir6.1 knockdown inhibited M2 polarization and simultaneously exaggerated M1 microglial inflammatory responses, while Kir6.1 overexpression promoted M2 polarization and synchronously alleviated the toxic phase of M1 microglia polarization. Furthermore, we observed that the Kir6.1 deficiency dramatically exacerbated dopaminergic neuron death companied by microglia activation in mouse model of PD. Mechanistically, Kir6.1 deficiency enhanced the activation of p38 MAPK–NF-κB pathway and increased the ratio of M1/M2 markers in the substantia nigra compacta of mouse model of PD. Suppression of p38 MAPK in vivo partially rescued the deleterious effects of Kir6.1 ablation on microglia phenotype and dopaminergic neuron death. Collectively, our findings reveal that Kir6.1/K-ATP channel modulates microglia phenotypes transition via inhibition of p38 MAPK–NF-κB signaling pathway and Kir6.1/K-ATP channel may be a promising therapeutic target for PD.

Animal Toxins as Therapeutic Tools to Treat Neurodegenerative Diseases

Neurodegenerative diseases affect millions of individuals worldwide. So far, no disease-modifying drug is available to treat patients, making the search for effective drugs an urgent need. Neurodegeneration is triggered by the activation of several cellular processes, including oxidative stress, mitochondrial impairment, neuroinflammation, aging, aggregate formation, glutamatergic excitotoxicity, and apoptosis. Therefore, many research groups aim to identify drugs that may inhibit one or more of these events leading to neuronal cell death. Venoms are fruitful natural sources of new molecules, which have been relentlessly enhanced by evolution through natural selection. Several studies indicate that venom components can exhibit selectivity and affinity for a wide variety of targets in mammalian systems. For instance, an expressive number of natural peptides identified in venoms from animals, such as snakes, scorpions, bees, and spiders, were shown to lessen inflammation, regulate glutamate release, modify neurotransmitter levels, block ion channel activation, decrease the number of protein aggregates, and increase the levels of neuroprotective factors. Thus, these venom components hold potential as therapeutic tools to slow or even halt neurodegeneration. However, there are many technological issues to overcome, as venom peptides are hard to obtain and characterize and the amount obtained from natural sources is insufficient to perform all the necessary experiments and tests. Fortunately, technological improvements regarding heterologous protein expression, as well as peptide chemical synthesis will help to provide enough quantities and allow chemical and pharmacological enhancements of these natural occurring compounds. Thus, the main focus of this review is to highlight the most promising studies evaluating animal toxins as therapeutic tools to treat a wide variety of neurodegenerative conditions, including Alzheimer’s disease, Parkinson’s disease, brain ischemia, glaucoma, amyotrophic lateral sclerosis, and multiple sclerosis.

Melittin suppresses tumor progression by regulating tumor-associated macrophages in a Lewis lung carcinoma mouse model

Tumor-associated macrophages (TAM) are a major component of tumor stroma. It has been reported that TAMs have M2-like phenotype and facilitate tumor progression by promoting angiogenesis and immunosuppression. Melittin, a major polypeptide of bee venom, has been widely studied as an anti-cancer drug due to its cytotoxicity to malignant cells. However, very little is known regarding the effect of melittin on immune cells in the tumor microenvironment. This study focuses on the effect of melittin on TAMs in a Lewis lung carcinoma mouse model. Melittin inhibited the rapid tumor growth compared to the control in vivo. Melittin increased the M1/M2 ratio of TAMs by selectively reducing the number of CD206⁺ M2-like TAMs while not altering the population of CD86⁺ M1-like TAMs. Melittin also preferentially binds to M2 macrophages, and this binding was not associated with phagocytosis. Gene and protein expression of vascular endothelial growth factor (Vegf) and mannose receptor C type 1 (Mrc1/CD206) was reduced in M2-like bone marrow-derived macrophages by melittin treatment, but there was no significant change in the gene level of Vegf and FMS-like tyrosine kinase 1 (Flt1/VEGFR1) in tumor cells in vitro. Additionally, the levels of VEGF and CD31, markers of angiogenesis, were significantly decreased by melittin treatment in tumor tissues. This study revealed a novel role for melittin in tumor treatment and suggested that melittin could be a promising therapeutic agent for targeting M2-like TAMs.

Beneficial effects of Panax ginseng for the treatment and prevention of neurodegenerative diseases: past findings and future directions

In recent years, several therapeutic drugs have been rationally designed and synthesized based on the novel knowledge gained from investigating the actions of biologically active chemicals derived from foods, plants, and medicinal herbs. One of the major advantages of these naturalistic chemicals is their ability to interact with multiple targets in the body resulting in a combined beneficial effect. Ginseng is a perennial herb (Araliaceae family), a species within the genus Panax, and a highly valued and popular medicinal plant. Evidence for the medicinal and health benefits of Panax ginseng and its components in preventing neurodegeneration has increased significantly in the past decade. The beneficial effects of P. ginseng on neurodegenerative diseases have been attributed primarily to the antioxidative and immunomodulatory activities of its ginsenoside components. Mechanistic studies on the neuroprotective effects of ginsenosides revealed that they act not only as antioxidants but also as modulators of intracellular neuronal signaling and metabolism, cell survival/death genes, and mitochondrial function. The goal of the present paper is to provide a brief review of recent knowledge and developments concerning the beneficial effects as well as the mechanism of action of P. ginseng and its components in the treatment and prevention of neurodegenerative diseases.