Targeting spinal microglia with fexofenadine-loaded nanoparticles prolongs pain relief in a rat model of neuropathic pain

PLGA nanoparticle-mediated anti-inflammatory gene delivery for the treatment of neuropathic pain

AIM

This study aimed to mitigate neuropathic pain behavior in a sciatic nerve transection (SNT)-induced mouse model by delivering anti-inflammatory cytokines - interleukin-4 (IL-4), interleukin-10 (IL-10), and transforming growth factor-beta 1 (TGF-β1) - via poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles (NPs).

MATERIALS & METHODS

Upon gene delivery of IL-4, IL-10, and TGF- β1, the anti-inflammatory effects and induction of microglia M2 polarization were evaluated. Plasmid (IL-4, IL-10, and TGF-β1)-encapsulated PLGA NPs (PLGA@IL-4, PLGA@IL-10, and PLGA@TGF-β1) were synthesized and characterized for size, zeta potential, cellular toxicity, and cellular uptake. The analgesic effect of anti-inflammatory gene delivery using PLGA NPs was then assessed in a mouse model of neuropathic pain.

RESULTS

Gene delivery of IL-4, IL-10, and TGF-β1 showed a significant anti-inflammatory effect in LPS-treated cells and IL-4 strongly promoted microglia M2 polarization in vitro. PLGA NPs successfully delivered the anti-inflammatory cytokine-coding genes into mouse spinal cord cells, specifically targeting microglia. PLGA@IL-4, PLGA@IL-10, and PLGA@TGF-β1 NPs produced analgesic effects in a SNT-induced mouse neuropathic pain model. Notably, PLGA@IL-4 demonstrated the most effective and remarkably long-lasting analgesic effect, strongly enhancing microglia M2 polarization in spinal cord microglia.

CONCLUSION

Gene therapy using PLGA NPs for overexpression of anti-inflammatory cytokines could be a promising strategy for the treatment of neuropathic pain.

Neuronal STING-GAT1 signaling maintains paclitaxel-induced neuropathic pain in the spinal cord

ABSTRACT

Stimulator of interferon genes (STING), a pivotal immune regulator, has emerged as a contributor to nociception, yet its role in chronic pains remains still unknown. Here, we demonstrate that STING plays a dual role in normal and neuropathic pain in mature male rodents. Stimulator of interferon genes maintains type I interferon (IFN-I) level restraining pain sensitivity in normal and sham control, while activated STING/interferon regulatory factor 3 (IRF3) signaling increases the expression of gamma-aminobutyric acid (GABA) transporter 1 (GAT1) in the spinal cord (SC), thus, generating paclitaxel (PTX)-induced peripheral neuropathy. Genetic interference of STING (STING-/- mice) attenuated PTX-induced mechanical hypersensitivity with attenuated PTX-induced GAT1 increase, preventing PTX-induced increase in tonic GABAA inhibition of the spinal dorsal horn neurons. Stimulator of interferon genes regulates GAT expression through a TANK-binding kinase 1 (TBK1)-IRF3 signaling pathway, with IRF3 as a crucial transcription factor. Silencing neuronal STING, as opposed to its astrocytic counterpart, effectively restrained the PTX-induced mechanical hypersensitivity and GAT1 increase in the SC. Pharmacological inhibition of STING (H-151) efficiently diminished the TBK1/IRF3/GAT1 signaling pathway to alleviate PTX-induced mechanical hypersensitivity. Our findings show that STING-IRF3 serves a dual role: suppressing physiological nociception through IFN-I and acting as a transcriptional regulator of GAT1, contributing to chemotherapy-induced neuropathic pain.

Nanotechnology Approaches for Prevention and Treatment of Chemotherapy-Induced Neurotoxicity, Neuropathy, and Cardiomyopathy in Breast and Ovarian Cancer Survivors

Nanotechnology has emerged as a promising approach for the targeted delivery of therapeutic agents while improving their efficacy and safety. As a result, nanomaterial development for the selective targeting of cancers, with the possibility of treating off-target, detrimental sequelae caused by chemotherapy, is an important area of research. Breast and ovarian cancer are among the most common cancer types in women, and chemotherapy is an essential treatment modality for these diseases. However, chemotherapy-induced neurotoxicity, neuropathy, and cardiomyopathy are common side effects that can affect breast and ovarian cancer survivors quality of life. Therefore, there is an urgent need to develop effective prevention and treatment strategies for these adverse effects. Nanoparticles (NPs) have extreme potential for enhancing therapeutic efficacy but require continued research to elucidate beneficial interventions for women cancer survivors. In short, nanotechnology-based approaches have emerged as promising strategies for preventing and treating chemotherapy-induced neurotoxicity, neuropathy, and cardiomyopathy. NP-based drug delivery systems and therapeutics have shown potential for reducing the side effects of chemotherapeutics while improving drug efficacy. In this article, the latest nanotechnology approaches and their potential for the prevention and treatment of chemotherapy-induced neurotoxicity, neuropathy, and cardiomyopathy in breast and ovarian cancer survivors are discussed.

Harnessing nanomedicine for modulating microglial states in the central nervous system disorders: Challenges and opportunities

Microglia are essential for maintaining homeostasis and responding to pathological events in the central nervous system (CNS). Their dynamic and multidimensional states in different environments are pivotal factors in various CNS disorders. However, therapeutic modulation of microglial states is challenging due to the intricate balance these cells maintain in the CNS environment and the blood-brain barrier's restriction of drug delivery. Nanomedicine presents a promising avenue for addressing these challenges, offering a method for the targeted and efficient modulation of microglial states. This review covers the challenges faced in microglial therapeutic modulation and potential use of nanoparticle-based drug delivery systems. We provide an in-depth examination of nanoparticle applications for modulating microglial states in a range of CNS disorders, encompassing neurodegenerative and autoimmune diseases, infections, traumatic injuries, stroke, tumors, chronic pain, and psychiatric conditions. This review highlights the recent advancements and future prospects in nanomedicine for microglial modulation, paving the way for future research and clinical applications of therapeutic interventions in CNS disorders.

Development of fexofenadine self-microemulsifying delivery systems: an efficient way to improve intestinal permeability

Aim: The present study aimed to prepare and evaluate fexofenadine self-microemulsifying drug-delivery systems (SMEDDS) formulation and to determine and compare its intestinal permeability using in situ single-pass intestinal perfusion (SPIP) technique.Methods: Fexofenadine-loaded SMEDDS were prepared and optimized. Droplet size, polydispersity index, zeta potential, drug release and intestinal permeability were evaluated.Results: Optimized formulation consisted of 15% oil, 80% surfactant and 5% cosolvent. Droplet size and drug loading of optimized formulation was 13.77 nm and 60 mg/g and it has released 90% of its drug content. Intestinal permeability of fexofenadine was threefold enhanced in SMEDDS compared with free fexofenadine.Conclusion: The results of our study revealed that SMEDDS could be a promising tool for oral delivery of fexofenadine with enhanced dissolution rate and intestinal permeability.

Rejuvenating aged microglia by p16ink4a-siRNA-loaded nanoparticles increases amyloid-β clearance in animal models of Alzheimer's disease

Age-dependent accumulation of amyloid plaques in patients with sporadic Alzheimer's disease (AD) is associated with reduced amyloid clearance. Older microglia have a reduced ability to phagocytose amyloid, so phagocytosis of amyloid plaques by microglia could be regulated to prevent amyloid accumulation. Furthermore, considering the aging-related disruption of cell cycle machinery in old microglia, we hypothesize that regulating their cell cycle could rejuvenate them and enhance their ability to promote more efficient amyloid clearance. First, we used gene ontology analysis of microglia from young and old mice to identify differential expression of cyclin-dependent kinase inhibitor 2A (p16ink4a), a cell cycle factor related to aging. We found that p16ink4a expression was increased in microglia near amyloid plaques in brain tissue from patients with AD and 5XFAD mice, a model of AD. In BV2 microglia, small interfering RNA (siRNA)-mediated p16ink4a downregulation transformed microglia with enhanced amyloid phagocytic capacity through regulated the cell cycle and increased cell proliferation. To regulate microglial phagocytosis by gene transduction, we used poly (D,L-lactic-co-glycolic acid) (PLGA) nanoparticles, which predominantly target microglia, to deliver the siRNA and to control microglial reactivity. Nanoparticle-based delivery of p16ink4a siRNA reduced amyloid plaque formation and the number of aged microglia surrounding the plaque and reversed learning deterioration and spatial memory deficits. We propose that downregulation of p16ink4a in microglia is a promising strategy for the treatment of Alzheimer's disease.

Optimization of O/W Emulsion Solvent Evaporation Method for Itraconazole Sustained Release Microspheres

Itraconazole, a commonly used antifungal drug in the clinic approved by U.S. Food and Drug Administration (FDA), has been gradually found to have anti-tumor, angiogenesis inhibition and other pharmacological activities. However, its poor water solubility and potential toxicity limited its clinical application. In order to improve the water solubility and reduce the side effects caused by the high concentration of itraconazole, a novel preparation method of itraconazole sustained release microspheres was established in this study. Firstly, five kinds of polylactic acid-glycolic acid (PLGA) microspheres loaded with itraconazole were prepared by oil/water (O/W) emulsion solvent evaporation and then characterized by infrared spectroscopy. Then the particle size and morphology of the microspheres were observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). After that, the particle size distribution, drug loading rate, entrapment efficiency, and drug release experiments were evaluated. Our results showed the microspheres prepared in this study had uniform particle size distribution and good integrity. Further study found that the average drug loading of the five kinds of microspheres prepared with PLGA 7505, PLGA 7510, PLGA 7520, PLGA 5020 and PLGA 0020 were 16.88, 17.72, 16.72, 16.57, and 16.64%, respectively, and the encapsulation rate all reached about 100%. More surprisingly, the release experimental results showed that the microspheres prepared with PLGA 7520 did not show sudden release, showing good sustained release performance and high drug release rate. To sum up, this study optimized the preparation method of sustained-release microspheres without sudden release, which provides a new solution for the delivery of itraconazole in the clinic.