Chemotherapy-induced Peripheral Neuropathy In Mice Research Articles

Abstract 2962: Chemotherapy induced senescence drives peripheral neuropathy

Abstract Chemotherapy is a mainstay of cancer therapy. Unfortunately, while chemotherapy can profoundly impact disease free survival, it is often accompanied with devastating side effects including hair loss, bone loss, cognitive impairment (referred to as "brain fog"), and peripheral neuropathies. While many of these side effects may subside after the completion of chemotherapy, some persist for a lifetime, substantially compromising the quality of life for survivors. Particularly insidious is chemotherapy-induced peripheral neuropathy (CIPN), which can impair a patient's ability to care for themselves. Shockingly, in over 30% of patients, CIPN persists even after the cessation of chemotherapy, subjecting them to a lifetime of numbness and/or pain. Paclitaxel (PTX), a common treatment for breast cancer, induces CIPN in 61-92% of patients depending on the administered dose. Unfortunately, there are currently no preventative or curative measures for CIPN resulting in side effects that persist for months or even years after the cessation of chemotherapy. Considering chemotherapy can trigger cellular senescence, leading to the release of a diverse array of factors collectively known as the senescence-associated secretory phenotype (SASP) that are capable of negatively influencing neighboring cells. To determine if senescence played a role in CIPN we treated with PTX and found that animals displayed reduced axon innervation in the paws and diminished paw withdrawal responses during the von Frey assay, characteristic symptoms of CIPN. To determine if senescent drove PTX-induced CIPN, we utilized the INKATTAC (INK) mouse, a model in which a p16INK4a promoter drives an inducible suicide transgene to eliminate p16+ senescent cells following treatment with AP20187 (AP). Employing the INK mouse, we successfully prevented CIPN by eliminating PTX-induced senescent cells. Furthermore, through bone marrow (BM) transplant studies using BM from INK mice into wildtype recipients, we failed to prevent CIPN. This result establishes that senescent immune cells, do not contribute to CIPN. In an independent approach, we found that senolytic drugs (kill senescent cells), such as dasatinib and quercetin (DQ) or ABT737 (ABT), effectively prevented and reversed CIPN in mice. Additionally, since the p38MAPK pathway has been shown to regulate SASP mRNA stability, we treated with p38 and MK2 inhibitors and found that inhibition prevented CIPN in mice. To address the mechanism behind CIPN we have carried out single cell RNA sequencing (scRNA-seq) to identify the cell population senescing in response to chemotherapy. These analyses will allow us to understand the mechanisms that drive CIPN and may lead to new treatments for patients suffering from CIPN. Citation Format: Taylor Malachowski, Ganesh Kumar Raut, Xianmin Luo, Satarupa Mullick Bagchi, Sheila Stewart. Chemotherapy induced senescence drives peripheral neuropathy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2962.

Spinal Neuronal miR-124 Inhibits Microglial Activation and Contributes to Preventive Effect of Electroacupuncture on Chemotherapy-Induced Peripheral Neuropathy in Mice.

Chemotherapy-induced peripheral neuropathy (CIPN) is a persistent and irreversible side effect of antineoplastic agents. Patients with CIPN usually show chronic pain and sensory deficits with glove-and-stocking distribution. However, whether spinal neuronal microRNA (miR)-124 is involved in cisplatin-induced peripheral neuropathy remains to be studied. In this study, miR-124 was significantly reduced in the spinal dorsal horn in CIPN mice. Overexpression of neuronal miR-124 induced by injecting adeno-associated virus with neuron-specific promoter into the spinal cord of mice prevented the development of mechanical allodynia, sensory deficits, and the loss of intraepidermal nerve fibers induced by cisplatin. Meanwhile, cisplatin-induced M1 microglia activation and the release of proinflammatory cytokines were significantly inhibited by overexpression of neuronal miR-124. Furthermore, electroacupuncture (EA) treatment upregulated miR-124 expression in the spinal dorsal horn of CIPN mice. Interestingly, downregulation of spinal neuronal miR-124 significantly inhibited the regulatory effect of EA on CIPN and microglia activity as well as spinal neuroinflammation induced by cisplatin. These results demonstrate that spinal neuronal miR-124 is involved in the prevention and treatment of EA on cisplatin-induced peripheral neuropathy in mice. Our findings suggest that spinal neuronal miR-124 might be a potential target for EA effect, and we provide, to our knowledge, a new experimental basis for EA prevention of CIPN.

A partial agonist of PPARγ prevents paclitaxel-induced peripheral neuropathy in mice, by inhibiting neuroinflammation.

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of paclitaxel, affecting 30-50% of patients. Increased survival and concern with patients' quality of life have encouraged the search for new tools to prevent paclitaxel-induced neuropathy. This study presents the glitazone 4-[(Z)-(2,4-dioxo-1,3-thiazolidin-5-ylidene)methyl]-N-phenylbenzene-sulfonamide (TZD-A1) as a partial agonist of peroxisome proliferator-activated receptor γ (PPARγ), its toxicological profile and effects on paclitaxel-induced CIPN in mice. Interactions of TZD-A1 with PPARγ were analysed using in silico docking and in vitro reporter gene assays. Pharmacokinetics and toxicity were evaluated using in silico, in vitro and in vivo (C57Bl/6 mice) analyses. Effects of TZD-A1 on CIPN were investigated in paclitaxel-injected mice. Axonal and dorsal root ganglion damage, mitochondrial complex activity and cytokine levels, brain-derived neurotrophic factor (BDNF), nuclear factor erythroid 2-related factor 2 (Nrf2) and PPARγ, were also measured. Docking analysis predicted TZD-A1 interactions with PPARγ compatible with partial agonism, which were corroborated by in vitro reporter gene assays. Good oral bioavailability and safety profile of TZD-A1 were shown in silico, in vitro and in vivo. Paclitaxel-injected mice, concomitantly treated with TZD-A1 by i.p. or oral administration, exhibited decreased mechanical and thermal hypersensitivity, effects apparently mediated by inhibition of neuroinflammation and mitochondrial damage, through increasing Nrf2 and PPARγ levels, and up-regulating BDNF. TZD-A1, a partial agonist of PPARγ, provided neuroprotection and reduced hypersensitivity induced by paclitaxel. Allied to its safety profile and good bioavailability, TZD-A1 is a promising drug candidate to prevent and treat CIPN in cancer patients.

Protease-Activated Receptor 2 (PAR2) Expressed in Sensory Neurons Contributes to Signs of Pain and Neuropathy in Paclitaxel Treated Mice

Chemotherapy-induced peripheral neuropathy (CIPN) is a common, dose-limiting side effect of cancer therapy. Protease-activated receptor 2 (PAR2) is implicated in a variety of pathologies, including CIPN. In this study, we demonstrate the role of PAR2 expressed in sensory neurons in a paclitaxel (PTX)-induced model of CIPN in mice. PAR2 knockout/wildtype (WT) mice and mice with PAR2 ablated in sensory neurons were treated with PTX administered via intraperitoneal injection. In vivo behavioral studies were done in mice using von Frey filaments and the Mouse Grimace Scale. We then examined immunohistochemical staining of dorsal root ganglion (DRG) and hind paw skin samples from CIPN mice to measure satellite cell gliosis and intra-epidermal nerve fiber (IENF) density. The pharmacological reversal of CIPN pain was tested with the PAR2 antagonist C781. Mechanical allodynia caused by PTX treatment was alleviated in PAR2 knockout mice of both sexes. In the PAR2 sensory neuronal conditional knockout (cKO) mice, both mechanical allodynia and facial grimacing were attenuated in mice of both sexes. In the DRG of the PTX-treated PAR2 cKO mice, satellite glial cell activation was reduced compared to control mice. IENF density analysis of the skin showed that the PTX-treated control mice had a reduction in nerve fiber density while the PAR2 cKO mice had a comparable skin innervation as the vehicle-treated animals. Similar results were seen with satellite cell gliosis in the DRG, where gliosis induced by PTX was absent in PAR cKO mice. Finally, C781 was able to transiently reverse established PTX-evoked mechanical allodynia. PerspectiveOur work demonstrates that PAR2 expressed in sensory neurons plays a key role in PTX-induced mechanical allodynia, spontaneous pain, and signs of neuropathy, suggesting PAR2 as a possible therapeutic target in multiple aspects of PTX CIPN.

Neutrophil extracellular traps as a unique target in the treatment of chemotherapy-induced peripheral neuropathy.

Chemotherapy-induced peripheral neuropathy (CIPN) is a severe dose-limiting side effect of chemotherapy and remains a huge clinical challenge. Here, we explore the role of microcirculation hypoxia induced by neutrophil extracellular traps (NETs) in the development of CIPN and look for potential treatment. The expression of NETs in plasma and dorsal root ganglion (DRG) are examined by ELISA, IHC, IF and Western blotting. IVIS Spectrum imaging and Laser Doppler Flow Metry are applied to explore the microcirculation hypoxia induced by NETs in the development of CIPN. Stroke Homing peptide (SHp)-guided deoxyribonuclease 1 (DNase1) is used to degrade NETs. The level of NETs in patients received chemotherapy increases significantly. And NETs accumulate in the DRG and limbs in CIPN mice. It leads to disturbed microcirculation and ischemic status in limbs and sciatic nerves treated with oxaliplatin (L-OHP). Furthermore, targeting NETs with DNase1 significantly reduces the chemotherapy-induced mechanical hyperalgesia. The pharmacological or genetic inhibition on myeloperoxidase (MPO) or peptidyl arginine deiminase-4 (PAD4) dramatically improves microcirculation disturbance caused by L-OHP and prevents the development of CIPN in mice. In addition to uncovering the role of NETs as a key element in the development of CIPN, our finding provides a potential therapeutic strategy that targeted degradation of NETs by SHp-guided DNase1 could be an effective treatment for CIPN. This study was funded by the National Natural Science Foundation of China81870870, 81971047, 81773798, 82271252; Natural Science Foundation of Jiangsu ProvinceBK20191253; Major Project of "Science and Technology Innovation Fund" of Nanjing Medical University2017NJMUCX004; Key R&D Program (Social Development) Project of Jiangsu ProvinceBE2019732; Nanjing Special Fund for Health Science and Technology DevelopmentYKK19170.

HDAC6 Inhibition Reverses Cisplatin-Induced Mechanical Hypersensitivity via Tonic Delta Opioid Receptor Signaling.

Peripheral neuropathic pain induced by the chemotherapeutic cisplatin can persist for months to years after treatment. Histone deacetylase 6 (HDAC6) inhibitors have therapeutic potential for cisplatin-induced neuropathic pain since they persistently reverse mechanical hypersensitivity and spontaneous pain in rodent models. Here, we investigated the mechanisms underlying reversal of mechanical hypersensitivity in male and female mice by a 2 week treatment with an HDAC6 inhibitor, administered 3 d after the last dose of cisplatin. Mechanical hypersensitivity in animals of both sexes treated with the HDAC6 inhibitor was temporarily reinstated by a single injection of the neutral opioid receptor antagonist 6β-naltrexol or the peripherally restricted opioid receptor antagonist naloxone methiodide. These results suggest that tonic peripheral opioid ligand-receptor signaling mediates reversal of cisplatin-induced mechanical hypersensitivity after treatment with an HDAC6 inhibitor. Pointing to a specific role for δ opioid receptors (DORs), Oprd1 expression was decreased in DRG neurons following cisplatin administration, but normalized after treatment with an HDAC6 inhibitor. Mechanical hypersensitivity was temporarily reinstated in both sexes by a single injection of the DOR antagonist naltrindole. Consistently, HDAC6 inhibition failed to reverse cisplatin-induced hypersensitivity when DORs were genetically deleted from advillin+ neurons. Mechanical hypersensitivity was also temporarily reinstated in both sexes by a single injection of a neutralizing antibody against the DOR ligand met-enkephalin. In conclusion, we reveal that treatment with an HDAC6 inhibitor induces tonic enkephalin-DOR signaling in peripheral sensory neurons to suppress mechanical hypersensitivity.SIGNIFICANCE STATEMENT Over one-fourth of cancer survivors suffer from intractable painful chemotherapy-induced peripheral neuropathy (CIPN), which can last for months to years after treatment ends. HDAC6 inhibition is a novel strategy to reverse CIPN without negatively interfering with tumor growth, but the mechanisms responsible for persistent reversal are not well understood. We built on evidence that the endogenous opioid system contributes to the spontaneous, apparent resolution of pain caused by nerve damage or inflammation, referred to as latent sensitization. We show that blocking the δ opioid receptor or its ligand enkephalin unmasks CIPN in mice treated with an HDAC6 inhibitor (latent sensitization). Our work provides insight into the mechanisms by which treatment with an HDAC6 inhibitor apparently reverses CIPN.

Kratom alkaloid mitragynine: Inhibition of chemotherapy-induced peripheral neuropathy in mice is dependent on sex and active adrenergic and opioid receptors.

Mitragynine (MG) is an alkaloid found in Mitragyna speciosa (kratom) that is used as an herbal remedy for pain relief and opioid withdrawal. MG acts at μ-opioid and α-adrenergic receptors in vitro, but the physiological relevance of this activity in the context of neuropathic pain remains unknown. The purpose of the present study was to characterize the effects of MG in a mouse model of chemotherapy-induced peripheral neuropathy (CIPN), and to investigate the potential impact of sex on MG’s therapeutic efficacy. Inhibition of oxaliplatin-induced mechanical hypersensitivity was measured following intraperitoneal administration of MG. Both male and female C57BL/6J mice were used to characterize potential sex-differences in MG’s therapeutic efficacy. Pharmacological mechanisms of MG were characterized through pretreatment with the opioid and adrenergic antagonists naltrexone, prazosin, yohimbine, and propranolol (1, 2.5, 5 mg/kg). Oxaliplatin produced significant mechanical allodynia of equal magnitude in both male and females, which was dose-dependently attenuated by repeated MG exposure. MG was more potent in males vs females, and the highest dose of MG (10 mg/kg) exhibited greater anti-allodynic efficacy in males. Mechanistically, activity at µ-opioid, α1- and α2-adrenergic receptors, but not β-adrenergic receptors contributed to the effects of MG against oxaliplatin-induced mechanical hypersensitivity. Repeated MG exposure significantly attenuated oxaliplatin-induced mechanical hypersensitivity with greater potency and efficacy in males, which has crucial implications in the context of individualized pain management. The opioid and adrenergic components of MG indicate that it shares pharmacological properties with clinical neuropathic pain treatments.

Kratom Alkaloid Mitragynine: Inhibition of Chemotherapy-Induced Peripheral Neuropathy in Mice is Dependent on Sex and Active Adrenergic and Opioid Receptors

Kratom Alkaloid Mitragynine: Inhibition of Chemotherapy-Induced Peripheral Neuropathy in Mice is Dependent on Sex and Active Adrenergic and Opioid Receptors

Methods and protocols for chemotherapy-induced peripheral neuropathy (CIPN) mouse models using paclitaxel.

While cancer patients may have chemotherapeutics to thank for being cured of their malignancy, they are often left to suffer a disabling neuropathy induced by that same cancer treatment. This neuropathy, known as chemotherapy-induced peripheral neuropathy, or CIPN, is one of the most debilitating survivorship concerns for patients, with many citing hallmark symptoms of hyperalgesia, allodynia, and numbness, and subsequently reducing their dose or even ceasing treatment altogether. Investigations into this interplay between the antineoplastic activity of chemotherapeutic agents and the preservation of peripheral nerve health are therefore crucial for the development of CIPN treatment and prevention methods. Responding to need, current literature is inundated with varying preclinical models of CIPN. This chapter thus seeks to provide a detailed and reliable methodology for the induction and assessment of CIPN in mice, using a preclinical model that is both reproducible and translatable to several aspects of the clinical phenotype. Specifically, this chapter lays out a model for intermittent low-dose paclitaxel induction of CIPN in C57BL/6J mice, and a testing of this induction via von Frey filament mechanical hypersensitivity assays, a mechanical hyposensitivity (numbness) assay, and a cold-thermal allodynia assay (acetone test). These protocols can easily be adjusted to fit the needs of individual CIPN experiments, as stated throughout the chapter.

Nasal administration of mesenchymal stem cells reverses chemotherapy-induced peripheral neuropathy in mice

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most frequently reported adverse effects of cancer treatment. CIPN often persists long after treatment completion and has detrimental effects on patient’s quality of life. There are no efficacious FDA-approved drugs for CIPN. We recently demonstrated that nasal administration of mesenchymal stem cells (MSC) reverses the cognitive deficits induced by cisplatin in mice.Here we show that nasal administration of MSC after cisplatin- or paclitaxel treatment- completely reverses signs of established CIPN, including mechanical allodynia, spontaneous pain, and loss of intraepidermal nerve fibers (IENF) in the paw. The resolution of CIPN is associated with normalization of the cisplatin-induced decrease in mitochondrial bioenergetics in DRG neurons. Nasally administered MSC enter rapidly the meninges of the brain, spinal cord and peripheral lymph nodes to promote IL-10 production by macrophages.MSC-mediated resolution of mechanical allodynia, recovery of IENFs and restoration of DRG mitochondrial function critically depends on IL-10 production. MSC from IL-10 knockout animals are not capable of reversing the symptoms of CIPN. Moreover, WT MSC do not reverse CIPN in mice lacking IL-10 receptors on peripheral sensory neurons. In conclusion, only two nasal administrations of MSC fully reverse CIPN and the associated mitochondrial abnormalities via an IL-10 dependent pathway. Since MSC are already applied clinically, we propose that nasal MSC treatment could become a powerful treatment for the large group of patients suffering from neurotoxicities of cancer treatment.

Analgesic and antiallodynic activity of novel anticonvulsant agents derived from 3-benzhydryl-pyrrolidine-2,5-dione in mouse models of nociceptive and neuropathic pain

The objective of this study was to evaluate analgesic and antiallodynic activity of four new 3-benzhydryl-pyrrolidine-2,5-dione derivatives, which demonstrated previously anticonvulsant activity in the seizure tests in mice. Analgesic activity was examined in acute (the hot plate test), tonic (the formalin test), as well as neuropathic (the oxaliplatin-induced peripheral neuropathy) pain models in mice. Moreover, potential sedative properties and hepatotoxicity were evaluated. To establish the plausible mechanism of action, in vitro assays were carried out. All tested compounds RS 34, RS 37, RS 48, and RS 49, similarly to pregabalin, were active in the second phase of formalin test, a model of tonic pain. The most promising effect was observed for compounds RS 34, RS 48, and RS 49, which in a statistically significant way attenuated the nocifensive response at all tested doses 1, 10, and 30 mg/kg. Furthermore, all compounds at a dose of 30 mg/kg revealed antiallodynic activity in neuropathic pain related to chemotherapy-induced peripheral neuropathy in mice. In experimental tests on three compounds RS 34, RS 37 and RS 48 at active doses no sedative properties were registered. In the in vitro assay the selected molecule RS 34 did not induce cytotoxic effect on hepatoma cells. The binding and functional studies did not provide firm evidence on possible mechanism of action of these derivatives. In conclusion, the tested pyrrolidine-2,5-dione derivatives with antiseizure activity exerted also analgesic and antiallodynic effects in mouse models of pain.

High mobility group box-1-toll-like receptor 4-phosphatidylinositol 3-kinase/protein kinase B-mediated generation of matrix metalloproteinase-9 in the dorsal root ganglion promotes chemotherapy-induced peripheral neuropathy.

Chemotherapy-induced peripheral neuropathy (CIPN) is a significant side effect of chemotherapeutics. The mechanisms of CIPN remain substantially unidentified, although inflammation-induced peripheral sensitization has been indicated as an important factor. Here, we aimed to illustrate the role of the matrix metalloproteinase (MMP)-9-related signaling pathway in the process of CIPN. Oxaliplatin (L-OHP) was administered to mice to establish the CIPN model. Gelatin zymography was used to measure MMP-9/2 activities. Western blotting and immunohistochemistry were used to measure the expression of high-mobility group box-1 (HMGB-1), calcitonin gene-related peptide and ionized calcium-binding adapter molecule 1. Mechanical withdrawal was measured by von Frey hairs testing. Raw 264.7 cells and SH-SY5Y cells were cultured to investigate cell signaling in vitro. Here, we report that L-OHP-induced mechanical pain in mice with significant MMP-9/2 activation in dorsal root ganglion (DRG) neurons. MMP-9 inhibition or knockout alleviated the occurrence of CIPN directly. MMP-9/2 were released from macrophages and neurons in the DRG via the HMGB-1-toll-like receptor 4 (TLR4)-phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) axis, because MMP-9/2 activities could be reduced by macrophage scavengers or PI3Kγ knockout in CIPN mice. The in vitro data revealed that induced MMP-9 activity by recombinant HMGB-1 could be abolished by TLR4, PI3K or Akt inhibitors. Finally, it was shown that N-acetyl-cysteine (NAC) could reduce MMP-9/2 activities and attenuate CIPN effectively and safely. The HMGB-1-TLR4-PI3K/Akt-MMP-9 axis is involved in the crosstalk between macrophages and neurons in the pathological process of CIPN in mice. Direct inhibition of MMP-9 by NAC may be a potential therapeutic regimen for CIPN treatment.

P38/TF/HIF-α Signaling Pathway Participates in the Progression of CIPN in Mice

Chemotherapy induced peripheral neuropathy (CIPN) is a serious adverse effect of chemotherapeutics with limited pathogenetic mechanism been known. Whether microcirculatory disturbance is involved in CIPN has not been reported. Considering that tissue factor (TF) is an endogenous coagulation factor, we hypothesize CIPN may be induced by the high expression of TF in macrophages and sciatic nerve, which induces the molecular signal related to ischemia and hypoxia. Oxaliplatin (L-OHP) was used to establish CIPN model. Von Frey Hairs was used to measure nociception. The murine macrophage cell line Raw 264.7 was used for cell experiments. Gelatin zymography and western blotting were used to measure the activity or expression of protein. TF expression and MMP-9/2 activity in sciatic nerve and blood are significantly increased by L-OHP. L-OHP increased the release of HSP70 from macrophage and enhanced the expression of p-p38 and HIF-1α in vivo and in vitro. Hirudin significantly suppressed the overexpression of p38, HIF-1α and activation of MMP-9/2 induced by L-OHP and attenuated CIPN in mice. This study suggests that a novel HSP70-TLR-4-p38-TF-HIF-1a axis may play a pivotal role in the pathological process of CIPN. It is also shown that the use of anticoagulant Hirudin can inhibit the above mechanisms and improve CIPN.

Targeting Cannabinoid 1 and Delta Opioid Receptor Heteromers Alleviates Chemotherapy-Induced Neuropathic Pain.

Cannabinoid 1 (CB1R) and delta opioid receptors (DOR) associate to form heteromers that exhibit distinct pharmacological properties. Not much is known about CB1R-DOR heteromer location or signaling along the pain circuit in either animal models or patients with chemotherapy-induced peripheral neuropathy (CIPN). Here, we use paclitaxel to induce CIPN in mice and confirm the development of mechanical allodynia. Under these conditions, we find significant increases in CB1R-DOR heteromers in the dorsal spinal cord of mice with CIPN as well as in postmortem spinal cords from human subjects with CIPN compared to controls. Next, we investigated receptor signaling in spinal cords of mice with CIPN and found that treatment with a combination of low signaling doses of CB1R and DOR ligands leads to significant enhancement in G-protein activity that could be selectively blocked by the CB1R-DOR antibody. Consistent with this, administration of subthreshold doses of a combination of ligands (CB1R agonist, Hu-210, and DOR agonist, SNC80) leads to significant attenuation of allodynia in mice with CIPN that is not seen with the administration of individual ligands, and this could be blocked by the CB1R-DOR antibody. Together, these results imply that CB1R-DOR heteromers upregulated during CIPN-associated mechanical allodynia could serve as a potential target for treatment of neuropathic pain including CIPN.

Cisplatin educates CD8+ T cells to prevent and resolve chemotherapy-induced peripheral neuropathy in mice.

The mechanisms responsible for the persistence of chemotherapy-induced peripheral neuropathy (CIPN) in a significant proportion of cancer survivors are still unknown. Our previous findings show that CD8 T cells are necessary for the resolution of paclitaxel-induced mechanical allodynia in male mice. In this study, we demonstrate that CD8 T cells are not only essential for resolving cisplatin-induced mechanical allodynia, but also to normalize spontaneous pain, numbness, and the reduction in intraepidermal nerve fiber density in male and female mice. Resolution of CIPN was not observed in Rag2 mice that lack T and B cells. Reconstitution of Rag2 mice with CD8 T cells before cisplatin treatment normalized the resolution of CIPN. In vivo education of CD8 T cells by cisplatin was necessary to induce resolution of CIPN in Rag2 mice because adoptive transfer of CD8 T cells from naive wild-type mice to Rag2 mice after completion of chemotherapy did not promote resolution of established CIPN. The CD8 T-cell-dependent resolution of CIPN does not require epitope recognition by the T-cell receptor. Moreover, adoptive transfer of cisplatin-educated CD8 T cells to Rag2 mice prevented CIPN development induced by either cisplatin or paclitaxel, indicating that the activity of the educated CD8 T is not cisplatin specific. In conclusion, resolution of CIPN requires in vivo education of CD8 T cells by exposure to cisplatin. Future studies should examine whether ex vivo CD8 T cell education could be applied as a therapeutic strategy for treating or preventing CIPN in patients.

Circulating microRNA and automated motion analysis as novel methods of assessing chemotherapy-induced peripheral neuropathy in mice.

Chemotherapy-induced peripheral neuropathy (CiPN) is a serious adverse effect in the clinic, but nonclinical assessment methods in animal studies are limited to labor intensive behavioral tests or semi-quantitative microscopic evaluation. Hence, microRNA (miRNA) biomarkers and automated in-life behavioral tracking were assessed for their utility as non-invasive methods. To address the lack of diagnostic biomarkers, we explored miR-124, miR-183 and miR-338 in a CiPN model induced by paclitaxel, a well-known neurotoxic agent. In addition, conventional and Vium’s innovative Digital Vivarium technology-based in-life behavioral tests and postmortem microscopic examination of the dorsal root ganglion (DRG) and the sciatic nerve were performed. Terminal blood was collected on days 8 or 16, after 20 mg/kg paclitaxel was administered every other day for total of 4 or 7 doses, respectively, for plasma miRNA quantification by RT-qPCR. DRG and sciatic nerve samples were collected from mice sacrificed on day 16 for miRNA quantification. Among the three miRNAs analyzed, only miR-124 was statistically significantly increased (5 fold and 10 fold on day 8 and day 16, respectively). The increase in circulating miR-124 correlated with cold allodynia and axonal degeneration in both DRG and sciatic nerve. Automated home cage motion analysis revealed for the first time that nighttime motion was significantly decreased (P < 0.05) in paclitaxel-dosed animals. Although both increase in circulating miR-124 and decrease in nighttime motion are compelling, our results provide positive evidence warranting further testing using additional peripheral nerve toxicants and diverse experimental CiPN models.

Monoclonal Antibody Targeting the Matrix Metalloproteinase 9 Prevents and Reverses Paclitaxel-Induced Peripheral Neuropathy in Mice

Chemotherapy-induced peripheral neuropathy (CIPN) is a disabling condition accompanying several cancer drugs, including the front-line chemotherapeutic agent paclitaxel. Although CIPN can force dose reduction or even discontinuation of chemotherapy, affecting survival in cancer patients, there is no US Food and Drug Administration–approved treatment for CIPN. CIPN in mice is characterized by neuropathic pain (eg, mechanical allodynia) in association with oxidative stress and neuroinflammation in dorsal root ganglia (DRGs), as well as retraction of intraepidermal nerve fibers. Here, we report that paclitaxel-induced mechanical allodynia is associated with transcriptional increase in matrix metalloproteinase (MMP) 2 and 9 and decrease in metallopeptidase inhibitor 1 (TIMP1), a strong endogenous MMP9 inhibitor. Consistently, MMP9 protein levels are increased in DRG neurons in vivo and in vitro after paclitaxel treatment, and it is demonstrated, for the first time, that intrathecal injections of exogenous TIMP1 or a monoclonal antibody targeting MMP9 (MMP9 mAb) significantly prevented and reversed paclitaxel-induced mechanical allodynia in male and female mice. Analyses of DRG tissues showed that MMP9 mAb significantly decreased oxidative stress and neuroinflammatory mediators interleukin-6 and tumor necrosis factor α, as well as prevented paclitaxel-induced loss of intraepidermal nerve fibers. These findings suggest that MMP signaling plays a key role in paclitaxel-induced peripheral neuropathy, and MMP9 mAb may offer new therapeutic approaches for the treatment of CIPN. PerspectiveChemotherapy-induced peripheral neuropathy (CIPN) remains ineffectively managed in cancer patients, potentially leading to the discontinuation of an otherwise life-saving treatment. Here, we demonstrate that a monoclonal antibody targeting MMP9 alleviates neuropathic pain and several mechanisms linked to CIPN. This study is particularly relevant, because a humanized MMP9 antibody is already in advanced clinical trials for the treatment of colitis and cancer, and it may be straightforwardly repurposed for the relief of CIPN.

Novel amide derivatives of 1,3-dimethyl-2,6-dioxopurin-7-yl-alkylcarboxylic acids as multifunctional TRPA1 antagonists and PDE4/7 inhibitors: A new approach for the treatment of pain

A series of novel amide derivatives of 1,3-dimethyl-2,6-dioxopurin-7-yl-alkylcarboxylic acids designed using a structure-based computational approach was synthesized and assayed to evaluate their ability to block human TRPA1 channel and inhibit PDE4B/7A activity. We identified compounds 16 and 27 which showed higher potency against TRPA1 compared to HC-030031. In turn, compound 36 was the most promising multifunctional TRPA1 antagonist and PDE4B/7A dual inhibitor with IC50 values in the range of that of the reference rolipram and BRL-50481, respectively. Compound 36 as a combined TRPA1/PDE4B/PDE7A ligand was characterized by a distinct binding mode in comparison to 16 and 27, in the given protein targets. The inhibition of both cAMP-specific PDE isoenzymes resulted in a strong anti-TNF-α effect of 36in vivo. Moreover, the potent anti-inflammatory and analgesic efficacy of 36 was observed in animal models of pain and inflammation (formalin test in mice and carrageenan-induced paw edema in rats). This compound also displayed significant antiallodynic properties in the early phase of chemotherapy-induced peripheral neuropathy in mice. In turn, the pure TRPA1 antagonists 16 and 27 revealed a statistically significant antiallodynic effect in the formalin test and in the von Frey test performed in both phases of oxaliplatin-induced allodynia. Antiallodynic activity of the test compounds 16, 27 and 36 was observed at a dose range comparable to that of the reference drug – pregabalin. In conclusion, the proposed approach of pain treatment based on the concomitant blocking of TRPA1 channel and PDE4B/7A inhibitory activity appears to be interesting research direction for the future search for novel analgesics.

Protective Effect of a Mitochondria-Targeted Peptide against the Development of Chemotherapy-Induced Peripheral Neuropathy in Mice.

Several chemotherapeutic agents used for cancer treatment induce dose-limiting peripheral neuropathy that compromises patients' quality of life and limits cancer treatment. Recently, mitochondrial dysfunction has been shown to be involved in the mechanism of chemotherapy-induced peripheral neuropathy. SS-20 is a mitochondria-targeted peptide that promotes mitochondrial respiration and restores mitochondrial bioenergetics. In the present study, we examined the protective effect of SS-20 against the development of chemotherapy-induced peripheral neuropathy utilizing a murine model of peripheral neuropathy induced by oxaliplatin, a first-line chemotherapy agent for colon cancer. Weekly administrations of oxaliplatin induced peripheral neuropathy as demonstrated by the development of neuropathic pain and loss of intraepidermal nerve fibers in the hind paw. Continuous administration of SS-20 protected against the development of oxaliplatin-induced neuropathic pain and mitigated the loss of intraepidermal nerve fibers to normal levels. Our findings suggest that SS-20 may be a drug candidate for the prevention of chemotherapy-induced peripheral neuropathy.

The prevention of chemotherapy induced peripheral neuropathy by concurrent treatment with drugs used for bipolar disease: a retrospective chart analysis in human cancer patients.

Peripheral neuropathy is a major adverse effect in the use of chemotherapeutic drugs. In nearly 50% of patients, chemotherapy induced peripheral neuropathy (CIPN) has been reported as irreversible. With increasing numbers of patients surviving treatment as well as increasing duration of survival after treatment, reducing the side effects of chemotherapy and improving the quality of life has become a major focus of cancer survivorship. Multiple classes of chemotherapeutic drugs including taxanes, platinum agents and vinka alkaloids list peripheral neuropathy as the main dose-limiting side effect of treatment. We previously found that drugs that interfere with the microtubule function, including taxanes and vinca alkaloids, bind to neuronal calcium sensor 1 (NCS1), leading to aberrant calcium signaling. The altered calcium signaling can be mitigated by application of drugs used to treat bipolar disease (e.g., lithium and valproic acid) prior to initiation of chemotherapy. Because pre-treatment with these drugs prevented CIPN in mice treated with taxanes, we sought clinical evidence by performing a retrospective chart review study of the VA electronic health record to see whether or not there would be evidence to support our scientific belief that patients treated with lithium or valproic acid while receiving chemotherapy have a lower risk for development of CIPN than patients who received chemotherapy alone. Our data did provide evidence supporting the belief that treatment with lithium or valproic acid concurrently with chemotherapy was associated with a decreased incidence of developing CIPN.