Trimethoxyflavanone relieves Paclitaxel-induced neuropathic pain via inhibiting expression and activation of P2X7 and production of CGRP in mice

Mesencephalic astrocyte-derived neurotrophic factor (MANF): A novel therapeutic target for chemotherapy-induced peripheral neuropathy via regulation of integrated stress response and neuroinflammation

Chemotherapy-induced peripheral neuropathy (CIPN) represents a severe complication, impacting up to 90% of cancer patients administered with chemotherapeutic agents such as oxaliplatin. The purpose of our study was to examine the potential role and therapeutic efficacy of Mesencephalic Astrocyte-derived Neurotrophic Factor (MANF), given its recognized neuroprotective and immunomodulatory properties in diverse neurological disorders. Utilizing an oxaliplatin-induced CIPN mouse model, we investigated MANF expression in the dorsal root ganglia (DRG) and spinal cord, and evaluated the impacts of AAV-mediated MANF overexpression on CIPN. Our findings revealed substantial downregulation of MANF expression in both the DRG and spinal cord of CIPN inflicted mice, with MANF majorly localized in neurons as opposed to glial cells. Intrathecal administration of AAV-MANF preceding oxaliplatin treatment yielded several beneficial results. MANF overexpression diminished mechanical hypersensitivity and decreased Calcitonin Gene-Related Peptide (CGRP) expression in DRG and the spinal dorsal horn. These enhancements were concomitant with modulation of the integrated stress response (ISR) and neuroinflammation. Intervention with AAV-MANF effectively regulated ISR markers (BiP, CHOP, and p-eIF2α), mitigated activation of microglia and astrocytes in the DRG and spinal dorsal horn, and inhibited NFκB and ERK inflammatory signaling pathways. To conclude, our study underscores the potential of MANF as a viable therapeutic target for CIPN, manifesting its ability to modulate ISR and neuroinflammation. These insights recommend that continued exploration of MANF-centered approaches could facilitate the advancement of more efficacious interventions for this incapacitating chemotherapy complication.

Sodium Danshensu alleviates bone cancer pain by inhibiting the osteoclast differentiation and CGRP expression

CONTEXT

The morbidity of bone cancer pain (BCP) is on the rise, yet current treatments have limited analgesic efficacy. Sodium Danshensu (SDSS), or sodium 3-(3,4-dihydroxyphenyl)-DL-lactate, exhibits anti-inflammatory, anti-osteoporotic properties. Current research shows that bone cancer pain is closely related to the development of osteoclasts.

OBJECTIVE

To investigate the analgesic effects of SDSS on BCP in mice and explore the underlying mechanisms.

MATERIALS & METHODS

Nociceptive behaviors in BCP mice were evaluated by paw withdrawal threshold (PWT) and limb using score (LUS). Network pharmacology, Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotation, and molecular docking identified potential targets. Histological analyses, Western blot, RT-qPCR, ELISA, and immunofluorescence staining were performed on mice femurs.

RESULTS

SDSS significantly increased PWT and LUS in BCP mice. Forty-three common targets were identified, with the estrogen signaling pathway showing the highest enrichment. Molecular docking analysis suggested a potential binding affinity between SDSS and ESRα. SDSS administration up-regulated ESRα expression and down-regulated RANKL, RANK, NFATc1, c-fos, TRAP, and Cathepsin K (CTSK). In addition, SDSS suppressed the abnormal increase of calcitonin gene-related peptide-positive (CGRP+) neural budding and expression in nerve endings, effects which were reversed by ESRa inhibitor ICI-182780.

CONCLUSIONS

SDSS relieves bone cancer pain by inhibiting osteoclast activity, providing a potential new drug option for cancer pain patients.

Focus on P2X7R in microglia: its mechanism of action and therapeutic prospects in various neuropathic pain models

Neuropathic pain (NP) is a common symptom of many diseases and is caused by direct or indirect damage to the nervous system. Tricyclic antidepressants and serotonin-norepinephrine reuptake inhibitors are typical drugs used in clinical practice to suppress pain. However, these drugs have drawbacks, including a short duration of action, a limited analgesic effect, and possible dependence and side effects. Therefore, developing more effective NP treatment strategies has become a priority in medical research and has attracted much research attention. P2X7 receptor (P2X7R) is a non-selective cation channel activated by adenosine triphosphate and is mainly expressed in microglia in the central nervous system. Microglial P2X7R plays an important role in pain regulation, suggesting that it could be a potential target for drug development. This review comprehensively and objectively discussed the latest research progress of P2X7R, including its structural characteristics, functional properties, relationship with microglial activation and polarization, mechanism of action, and potential therapeutic strategies in multiple NP models. This study aimed to provide in-depth insights into the association between P2X7R and NP and explore the mechanism of action of P2X7R in the pathological process of NP and the translational potential and clinical application prospects of P2X7R antagonists in pain treatment, providing a scientific basis for the precise treatment of NP.

Inhibition of histone deacetylase 6 alleviates neuropathic pain via direct regulating post-translation of spinal STAT3 and decreasing downstream C-C Motif Chemokine Ligand 7 synthesis

Neuropathic pain, a debilitating nerve injury-induced condition, remains a significant clinical challenge. This study evaluates the effect of histone deacetylase 6 (HDAC6) inhibition in a spared nerve injury (SNI) mouse model. Systemic administration of the selective HDAC6 inhibitor ACY-1215 (20 mg/kg/day, 14 days), alleviated SNI-induced pain in mice of both sexes. ACY-1215 increased acetylated signal transducer and activator of transcription 3 (Ac-STAT3) and reduced phosphorylated STAT3 (p-STAT3) in the lumbar spinal cord of SNI mice. HDAC6 and p-STAT3 were expressed in spinal dorsal horn neurons, and SNI-enhanced HDAC6/STAT3 interaction was reversed by ACY-1215. Neuronal STAT3 overexpression induced pain hypersensitivity and elevated p-STAT3, tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β), effects suppressed by ACY-1215. Cytokine profiling identified CC-chemokine ligand 7 (CCL7) as a key downstream effector of the HDAC6/STAT3 axis, with ACY-1215 attenuating SNI-induced CCL7 upregulation. HDAC6 knockdown in neurons reduced p-STAT3, while HDAC6 or STAT3 knockdown diminished CCL7 production. These findings demonstrate that ACY-1215 mitigates neuropathic pain by modulating STAT3 acetylation/phosphorylation and suppressing HDAC6/STAT3-driven CCL7 and cytokine release. This study underscores the role of the HDAC6/STAT3/CCL7 signaling axis in neuropathic pain and highlights the therapeutic potential of HDAC6 inhibitors for pain management.

Naringenin relieves paclitaxel-induced pain by suppressing calcitonin gene-related peptide signalling and enhances the anti-tumour action of paclitaxel

BACKGROUND AND PURPOSE

Chemotherapy-induced peripheral neuropathy (CIPN) commonly causes neuropathic pain, but its pathogenesis remains unclear, and effective therapies are lacking. Naringenin, a natural dihydroflavonoid compound, has anti-inflammatory, anti-nociceptive and anti-tumour activities. However, the effects of naringenin on chemotherapy-induced pain and chemotherapy effectiveness remain unexplored.

EXPERIMENTAL APPROACH

Female and male mouse models of chemotherapy-induced pain were established using paclitaxel. Effects of naringenin were assessed on pain induced by paclitaxel or calcitonin gene-related peptide (CGRP) and on CGRP expression in dorsal root ganglia (DRG) and spinal cord tissue. Additionally, we examined peripheral macrophage infiltration, glial activation, c-fos expression, DRG neuron excitability, microglial M1/M2 polarization, and phosphorylation of spinal NF-κB. Furthermore, we investigated the synergic effect and related mechanisms of naringenin and paclitaxel on cell survival of cancer cells in vitro.

KEY RESULTS

Systemic administration of naringenin attenuated paclitaxel-induced pain in both sexes. Naringenin reduced paclitaxel-enhanced CGRP expression in DRGs and the spinal cord, and alleviated CGRP-induced pain in naïve mice of both sexes. Naringenin mitigated macrophage infiltration and reversed paclitaxel-elevated c-fos expression and DRG neuron excitability. Naringenin decreased spinal glial activation and NF-κB phosphorylation in both sexes but influenced microglial M1/M2 polarization only in females. Co-administration of naringenin with paclitaxel enhanced paclitaxel's anti-tumour effect, impeded by an apoptosis inhibitor.

CONCLUSION AND IMPLICATIONS

Naringenin's anti-nociceptive mechanism involves CGRP signalling and neuroimmunoregulation. Furthermore, naringenin facilitates paclitaxel's anti-tumour action, possibly involving apoptosis. This study demonstrates naringenin's potential as a supplementary treatment in cancer therapy by mitigating side effects and potentiating efficacy of chemotherapy.

Chemotherapy-Induced Peripheral Neuropathy: A Recent Update on Pathophysiology and Treatment

Chemotherapy-induced peripheral neuropathy (CIPN) is a major long-lasting side effect of some chemotherapy drugs, which threatens cancer survival rate. CIPN mostly affects sensory neurons and occasionally motor neurons, causing numbness, tingling, discomfort, and burning pain in the upper and lower extremities. The pathophysiology of CIPN is not completely understood; however, it is believed that chemotherapies induce peripheral neuropathy via directly damaging mitochondria, impairing the function of ion channels, triggering immunological mechanisms, and disrupting microtubules. The treatment of CIPN is a medical challenge, and there are no approved pharmacological options. Currently, duloxetine and other antidepressants, antioxidant, anti-inflammatory, and ion-channel targeted therapies are commonly used in clinics to relieve the symptoms of CIPN. Several other types of drugs, such as cannabinoids, sigma-1 receptor antagonists, and nicotinamides ribose, are being evaluated in preclinical and clinical studies. This paper summarizes the information related to the physiology of CIPN and medicines that could be used for treating this condition.

Contributions of neuroimmune interactions to chemotherapy-induced peripheral neuropathy development and its prevention/therapy

Chemotherapy-induced peripheral neuropathy (CIPN) is a debilitating sequela that is difficult for both clinicians and cancer patients to manage. Precise mechanisms of CIPN remain elusive and current clinically prescribed therapies for CIPN have limited efficacy. Recent studies have begun investigating the interactions between the peripheral and central nervous systems and the immune system. Understanding these neuroimmune interactions may shift the paradigm of elucidating CIPN mechanisms. Although the contribution of immune cells to CIPN pathogenesis represents a promising area of research, its fully defined mechanisms have not yet been established. Therefore, in this review, we will discuss (i) current shortcoming of CIPN treatments, (ii) the roles of neuroimmune interactions in CIPN development and (iii) potential neuroimmune interaction-targeting treatment strategies for CIPN. Interestingly, monocytes/macrophages in dorsal root ganglia; microglia and astrocytes in spinal cord; mast cells in skin; and Schwann cell near peripheral nerves have been identified as inducers of CIPN behaviors, whereas T cells have been found to contribute to CIPN resolution. Additionally, nerve-resident immune cells have been targeted as prevention and/or therapy for CIPN using traditional herbal medicines, small molecule inhibitors, and intravenous immunoglobulins in a preclinical setting. Overall, unveiling neuroimmune interactions associated with CIPN may ultimately reduce cancer mortality and improve cancer patients' quality of life.

Monoclonal Antibody Targeting CGRP Relieves Cisplatin-Induced Neuropathic Pain by Attenuating Neuroinflammation

Chemotherapy-induced neuropathic pain (CIPN) is a common side effect of antitumor chemotherapeutic agents. It describes a pathological state of pain related to the cumulative dosage of the drug, significantly limiting the efficacy of antitumor treatment. Sofas strategies alleviating CIPN still lack. Calcitonin gene-related peptide (CGRP) is a neuropeptide involved in many pathologic pains. In this study, we explored the effects of CGRP blocking on CIPN and potential mechanisms. Total dose of 20.7 mg/kg cisplatin was used to establish a CIPN mouse model. Mechanical and thermal hypersensitivity was measured using von Frey hairs and tail flick test. Western blot and immunofluorescence were utilized to evaluate the levels of CGRP and activated astrocytes in mouse spinal cord, respectively. In addition, real-time quantitative PCR (RT-qPCR) was used to detect the level of inflammatory cytokines such as IL-6, IL-1β, and NLRP3 in vitro and in vivo. There are markedly increased CGRP expression and astrocyte activation in the spinal cord of mice following cisplatin treatment. Pretreatment with a monoclonal antibody targeting CGRP (ZR8 mAb) effectively reduced cisplatin-induced mechanical hypersensitivity and thermal nociceptive sensitization and attenuated neuroinflammation as marked by downregulated expression of IL-6, IL-1β, and NLRP3 in the mice spinal cord and spleen. Lastly, ZR8 mAb does not interfere with the antitumor effects of cisplatin in tumor-bearing mice. Our findings indicate that neutralizing CGRP with monoclonal antibody could effectively alleviate CIPN by attenuating neuroinflammation. CGRP is a promising therapeutic target for CIPN.

Naturally Inspired Molecules for Neuropathic Pain Inhibition-Effect of Mirogabalin and Cebranopadol on Mechanical and Thermal Nociceptive Threshold in Mice

BACKGROUND

Neuropathic pain is drug-resistant to available analgesics and therefore novel treatment options for this debilitating clinical condition are urgently needed. Recently, two drug candidates, namely mirogabalin and cebranopadol have become a subject of interest because of their potential utility as analgesics for chronic pain treatment. However, they have not been investigated thoroughly in some types of neuropathic pain, both in humans and experimental animals.

METHODS

This study used the von Frey test, the hot plate test and the two-plate thermal place preference test supported by image analysis and machine learning to assess the effect of intraperitoneal mirogabalin and subcutaneous cebranopadol on mechanical and thermal nociceptive threshold in mouse models of neuropathic pain induced by streptozotocin, paclitaxel and oxaliplatin.

RESULTS

Mirogabalin and cebranopadol effectively attenuated tactile allodynia in models of neuropathic pain induced by streptozotocin and paclitaxel. Cebranopadol was more effective than mirogabalin in this respect. Both drugs also elevated the heat nociceptive threshold in mice. In the oxaliplatin model, cebranopadol and mirogabalin reduced cold-exacerbated pain.

CONCLUSIONS

Since mirogabalin and cebranopadol are effective in animal models of neuropathic pain, they seem to be promising novel therapies for various types of neuropathic pain in patients, in particular those who are resistant to available analgesics.