Gene expression profile of sodium channel subunits in the anterior cingulate cortex during experimental paclitaxel-induced neuropathic pain in mice

Serum sodium ions and chloride ions associated with taxane-induced peripheral neuropathy in Chinese patients with early-stage breast cancer: A nation-wide multicenter study

BACKGROUND

Taxane-induced peripheral neuropathy (TIPN) is a debilitating adverse effect of cancer treatments with taxanes which may require a reduction or discontinuation chemotherapy and affect clinical and survival outcomes. A number of factors have contributed to the increasing prevalence of TIPN. Nonetheless, limited knowledge exists of potential prechemotherapy blood-based biochemical factors associated with TIPN development.

METHODS

We recruited breast cancer patients at seven cancer institutions in China. Participants aged 18 years or older with stage I to III breast cancer who scheduled to undergo primary neoadjuvant and adjuvant chemotherapy with taxanes were eligible. Eligible patients underwent patient-reported neuropathy assessments using the EORTC-CIPN20 questionnaire. Patients completed the questionnaire before commencing treatment and after every cycle. For every patient, we selected the highest TIPN toxicity score for analysis since the first cycle. The posttreatment TIPN severity was compared with blood-based biochemical factors within 30 days before commencing treatment. Independent samples t tests, Mann-Whitney U tests and linear regression were used to identify blood-based and clinical associations with TIPN development.

RESULTS

The study included 873 breast cancer participants who received paclitaxel, docetaxel or nanoparticle albumin-bound (nab)-paclitaxel. In the whole cohort, factors associated with higher TIPN toxicity scores were higher cumulative chemotherapy dose (β = 0.005; 95% CI, 0.004 to 0.006; P < .001), lower sodium ions (β = -0.24; 95% CI, -0.39 to -0.09; P = .002) and higher chloride ions (β = 0.30; 95% CI, 0.16 to 0.44; P < .001).

CONCLUSIONS

The findings suggest that breast cancer patients with a higher cumulative chemotherapy dose, lower pretreatment sodium ions, and higher pretreatment chloride ions receiving taxanes should receive closer monitoring to mitigate the development of short-term and long-term TIPN.

Utilizing machine learning algorithms to predict subject genetic mutation class from in silico models of neuronal networks

Background

Epilepsy is the fourth-most common neurological disorder, affecting an estimated 50 million patients globally. Nearly 40% of patients have uncontrolled seizures yet incur 80% of the cost. Anti-epileptic drugs commonly result in resistance and reversion to uncontrolled drug-resistant epilepsy and are often associated with significant adverse effects. This has led to a trial-and-error system in which physicians spend months to years attempting to identify the optimal therapeutic approach.

Objective

To investigate the potential clinical utility from the context of optimal therapeutic prediction of characterizing cellular electrophysiology. It is well-established that genomic data alone can sometimes be predictive of effective therapeutic approach. Thus, to assess the predictive power of electrophysiological data, machine learning strategies are implemented to predict a subject’s genetically defined class in an in silico model using brief electrophysiological recordings obtained from simulated neuronal networks.

Methods

A dynamic network of isogenic neurons is modeled in silico for 1-s for 228 dynamically modeled patients falling into one of three categories: healthy, general sodium channel gain of function, or inhibitory sodium channel loss of function. Data from previous studies investigating the electrophysiological and cellular properties of neurons in vitro are used to define the parameters governing said models. Ninety-two electrophysiological features defining the nature and consistency of network connectivity, activity, waveform shape, and complexity are extracted for each patient network and t-tests are used for feature selection for the following machine learning algorithms: Neural Network, Support Vector Machine, Gaussian Naïve Bayes Classifier, Decision Tree, and Gradient Boosting Decision Tree. Finally, their performance in accurately predicting which genetic category the subjects fall under is assessed.

Results

Several machine learning algorithms excel in using electrophysiological data from isogenic neurons to accurately predict genetic class with a Gaussian Naïve Bayes Classifier predicting healthy, gain of function, and overall, with the best accuracy, area under the curve, and F1. The Gradient Boosting Decision Tree performs the best for loss of function models indicated by the same metrics.

Conclusions

It is possible for machine learning algorithms to use electrophysiological data to predict clinically valuable metrics such as optimal therapeutic approach, especially when combining several models.

Mechanisms underlying paclitaxel-induced neuropathic pain: Channels, inflammation and immune regulations

Paclitaxel is a chemotherapeutic agent widely used for many types of malignancies. However, when paclitaxel is used to treat tumors, patients commonly experience severe neuropathic pain that is difficult to manage. The mechanism underlying paclitaxel-induced neuropathic pain remains unclear. Evidence demonstrates correlations between mechanisms of paclitaxel-mediated pain and associated actions of ion channels, neuroinflammation, mitochondrial damage, and other factors. This review provides a comprehensive analysis of paclitaxel-induced neuropathic pain mechanisms and suggestions for effective interventions.

Neuroinflammation in the anterior cingulate cortex: the potential supraspinal mechanism underlying the mirror-image pain following motor fiber injury

Background

Peripheral nerve inflammation or lesion can affect contralateral healthy structures, and thus result in mirror-image pain. Supraspinal structures play important roles in the occurrence of mirror pain. The anterior cingulate cortex (ACC) is a first-order cortical region that responds to painful stimuli. In the present study, we systematically investigate and compare the neuroimmune changes in the bilateral ACC region using unilateral- (spared nerve injury, SNI) and mirror-(L5 ventral root transection, L5-VRT) pain models, aiming to explore the potential supraspinal neuroimmune mechanism underlying the mirror-image pain.

Methods

The up-and-down method with von Frey hairs was used to measure the mechanical allodynia. Viral injections for the designer receptors exclusively activated by designer drugs (DREADD) were used to modulate ACC glutamatergic neurons. Immunohistochemistry, immunofluorescence, western blotting, protein microarray were used to detect the regulation of inflammatory signaling.

Results

Increased expressions of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and chemokine CX3CL1 in ACC induced by unilateral nerve injury were observed on the contralateral side in the SNI group but on the bilateral side in the L5-VRT group, representing a stronger immune response to L5-VRT surgery. In remote ACC, both SNI and L5-VRT induced robust bilateral increase in the protein level of Nav1.6 (SCN8A), a major voltage-gated sodium channel (VGSC) that regulates neuronal activity in the mammalian nervous system. However, the L5-VRT-induced Nav1.6 response occurred at PO 3d, earlier than the SNI-induced one, 7 days after surgery. Modulating ACC glutamatergic neurons via DREADD-Gq or DREADD-Gi greatly changed the ACC CX3CL1 levels and the mechanical paw withdrawal threshold. Neutralization of endogenous ACC CX3CL1 by contralateral anti-CX3CL1 antibody attenuated the induction and the maintenance of mechanical allodynia and eliminated the upregulation of CX3CL1, TNF-α and Nav1.6 protein levels in ACC induced by SNI. Furthermore, contralateral ACC anti-CX3CL1 also inhibited the expression of ipsilateral spinal c-Fos, Iba1, CD11b, TNF-α and IL-6.

Conclusions

The descending facilitation function mediated by CX3CL1 and its downstream cascade may play a pivotal role, leading to enhanced pain sensitization and even mirror-image pain. Strategies that target chemokine-mediated ACC hyperexcitability may lead to novel therapies for the treatment of neuropathic pain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02525-8.

Neuro-immune interactions in paclitaxel-induced peripheral neuropathy

BACKGROUND

Paclitaxel is a taxane-based chemotherapeutic agent used as a treatment in breast cancer. There is no effective prevention or treatment strategy for the most common side effect of peripheral neuropathy. In this manuscript, we reviewed the molecular mechanisms that contribute to paclitaxel-induced peripheral neuropathy (PIPN) with an emphasis on immune-related processes.

METHODS

A systematic search of the literature was conducted in PubMed, EMBASE and Cochrane Library. The SYRCLE's risk of bias tool was used to assess internal validity.

RESULTS

156 studies conducted with rodent models were included. The risk of bias was high due to unclear methodology. Paclitaxel induces changes in myelinated axons, mitochondrial dysfunction, and mechanical hypersensitivity by affecting ion channels expression and function and facilitating spinal transmission. Paclitaxel-induced inflammatory responses are important contributors to PIPN.

CONCLUSION

Immune-related processes are an important mechanism contributing to PIPN. Studies in humans that validate these mechanistic data are highly needed to facilitate the development of therapeutic strategies.

Review of the Role of the Brain in Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a common, debilitating, and dose-limiting side effect of many chemotherapy regimens yet has limited treatments due to incomplete knowledge of its pathophysiology. Research on the pathophysiology of CIPN has focused on peripheral nerves because CIPN symptoms are felt in the hands and feet. However, better understanding the role of the brain in CIPN may accelerate understanding, diagnosing, and treating CIPN. The goals of this review are to (1) investigate the role of the brain in CIPN, and (2) use this knowledge to inform future research and treatment of CIPN. We identified 16 papers using brain interventions in animal models of CIPN and five papers using brain imaging in humans or monkeys with CIPN. These studies suggest that CIPN is partly caused by (1) brain hyperactivity, (2) reduced GABAergic inhibition, (3) neuroinflammation, and (4) overactivation of GPCR/MAPK pathways. These four features were observed in several brain regions including the thalamus, periaqueductal gray, anterior cingulate cortex, somatosensory cortex, and insula. We discuss how to leverage this knowledge for future preclinical research, clinical research, and brain-based treatments for CIPN.

Taxane-induced neurotoxicity: Pathophysiology and therapeutic perspectives

Taxane-derived drugs are antineoplastic agents used for the treatment of highly common malignancies. Paclitaxel and docetaxel are the most commonly used taxanes; however, other drugs and formulations have been used, such as cabazitaxel and nab-paclitaxel. Taxane treatment is associated with neurotoxicity, a well-known and relevant side effect, very prevalent amongst patients undergoing chemotherapy. Painful peripheral neuropathy is the most dose-limiting side effect of taxanes, affecting up to 97% of paclitaxel-treated patients. Central neurotoxicity is an emerging side effect of taxanes and it is characterized by cognitive impairment and encephalopathy. Besides impairing compliance to chemotherapy treatment, taxane-induced neurotoxicity (TIN) can adversely affect the patient's life quality on a long-term basis. Despite the clinical relevance, not many reviews have comprehensively addressed taxane-induced neurotoxicity when they are used therapeutically. This article provides an up-to-date review on the pathophysiology of TIN and the novel potential therapies to prevent or treat this side effect.

Pathophysiological roles and therapeutic potential of voltage-gated ion channels (VGICs) in pain associated with herpesvirus infection

Herpesvirus is ranked as one of the grand old members of all pathogens. Of all the viruses in the superfamily, Herpes simplex virus type 1 (HSV-1) is considered as a model virus for a variety of reasons. In a permissive non-neuronal cell culture, HSV-1 concludes the entire life cycle in approximately 18–20 h, encoding approximately 90 unique transcriptional units. In latency, the robust viral gene expression is suppressed in neurons by a group of noncoding RNA. Historically the lesions caused by the virus can date back to centuries ago. As a neurotropic pathogen, HSV-1 is associated with painful oral lesions, severe keratitis and lethal encephalitis. Transmission of pain signals is dependent on the generation and propagation of action potential in sensory neurons. T-type Ca²⁺ channels serve as a preamplifier of action potential generation. Voltage-gated Na⁺ channels are the main components for action potential production. This review summarizes not only the voltage-gated ion channels in neuropathic disorders but also provides the new insights into HSV-1 induced pain.

The Medial Prefrontal Cortex as a Central Hub for Mental Comorbidities Associated with Chronic Pain

Chronic pain patients frequently develop and suffer from mental comorbidities such as depressive mood, impaired cognition, and other significant constraints of daily life, which can only insufficiently be overcome by medication. The emotional and cognitive components of pain are processed by the medial prefrontal cortex, which comprises the anterior cingulate cortex, the prelimbic, and the infralimbic cortex. All three subregions are significantly affected by chronic pain: magnetic resonance imaging has revealed gray matter loss in all these areas in chronic pain conditions. While the anterior cingulate cortex appears hyperactive, prelimbic, and infralimbic regions show reduced activity. The medial prefrontal cortex receives ascending, nociceptive input, but also exerts important top-down control of pain sensation: its projections are the main cortical input of the periaqueductal gray, which is part of the descending inhibitory pain control system at the spinal level. A multitude of neurotransmitter systems contributes to the fine-tuning of the local circuitry, of which cholinergic and GABAergic signaling are particularly emerging as relevant components of affective pain processing within the prefrontal cortex. Accordingly, factors such as distraction, positive mood, and anticipation of pain relief such as placebo can ameliorate pain by affecting mPFC function, making this cortical area a promising target region for medical as well as psychosocial interventions for pain therapy.

Upregulation of tumor necrosis factor-alpha in the anterior cingulate cortex contributes to neuropathic pain and pain-associated aversion

Injury associated pain involves subjective perception and emotional experience. The anterior cingulate cortex (ACC) is a key area involved in the affective component of pain processing. However, the neuroimmune mechanisms underlying enhanced ACC excitability following peripheral nerve injury are still not fully understood. Our previous work has shown that tumor necrosis factor-alpha (TNF-α) overexpression leads to peripheral afferent hyperexcitability and synaptic transmission potentiation in spinal cord. Here, we aimed to reveal the potential role of ACC TNF-α in ACC hyperexcitability and neuropathic pain. c-Fos, a widely used neuronal activity marker, was induced especially in contralateral ACC early [postoperative (PO) 1 h] and later (PO day 7 and 10) during the development of neuropathic pain. Spared nerve injury (SNI) elevated TNF-α level in contralateral ACC from PO day 5 to 14, delayed relative to decreased ipsilateral paw withdrawal threshold apparent from PO day 1 to 14. Microinjection of anti-TNF-α antibody into the ACC completely eliminated c-Fos overexpression and greatly attenuated pain aversion and mechanical allodynia induced by SNI, suggesting an important role of ACC TNF-α in the pain aversiveness and pain maintenance. Furthermore, modulating ACC pyramidal neurons via a Gi-coupled human M4 muscarinic receptor (hM4Di) or a Gq-coupled human M3 muscarinic receptor (hM3Dq), a type of designer receptors exclusively activated by designer drugs (DREADD), greatly changed the ACC TNF-α level and the mechanical paw withdrawal threshold. The positive interactions between TNF-α and ACC neurons might modulate the cytokine microenvironment thus contribute to the neuropathic pain.

Clinical and preclinical perspectives on Chemotherapy-Induced Peripheral Neuropathy (CIPN): a narrative review

This review provides an update on the current clinical and preclinical understanding of chemotherapy induced peripheral neuropathy (CIPN). The overview of the clinical syndrome includes a review of its assessment, diagnosis and treatment. CIPN is caused by several widely-used chemotherapeutics including paclitaxel, oxaliplatin, bortezomib. Severe CIPN may require dose reduction, or cessation, of chemotherapy, impacting on patient survival. While CIPN often resolves after chemotherapy, around 30% of patients will have persistent problems, impacting on function and quality of life. Early assessment and diagnosis is important, and we discuss tools developed for this purpose. There are no effective strategies to prevent CIPN, with limited evidence of effective drugs for treating established CIPN. Duloxetine has moderate evidence, with extrapolation from other neuropathic pain states generally being used to direct treatment options for CIPN. The preclinical perspective includes a discussion on the development of clinically-relevant rodent models of CIPN and some of the potentially modifiable mechanisms that have been identified using these models. We focus on the role of mitochondrial dysfunction, oxidative stress, immune cells and changes in ion channels from summary of the latest literature in these areas. Many causal mechanisms of CIPN occur simultaneously and/or can reinforce each other. Thus, combination therapies may well be required for most effective management. More effective treatment of CIPN will require closer links between oncology and pain management clinical teams to ensure CIPN patients are effectively monitored. Furthermore, continued close collaboration between clinical and preclinical research will facilitate the development of novel treatments for CIPN.

Prevention of paclitaxel-induced neuropathy by formulation approach

Chemotherapy-induced peripheral neuropathy (CIPN) is a major adverse effect of paclitaxel. Several liposome-based products have been approved and demonstrated superior efficacy and safety profiles for other drugs. The first objective of this work was to evaluate the effect of liposome formulation of paclitaxel (L-PTX) on neurotoxicity in-vitro and in-vivo in comparison to the standard Taxol® formulation. The second aim was to investigate the effect of formulation on paclitaxel biodistribution following intravenous administration in an animal model. Free paclitaxel was toxic to cell of neuronal origin (IC50 = 18.4 μg/mL) at a lower concentration than to lung cancer cells (IC50 = 59.1 μg/mL), and L-PTX demonstrated a comparable toxicity in both cell lines (IC50 = 31.8 and 33.7 μg/mL). Administration of L-PTX at 2 mg/kg per dose for a total of 4 doses on day 0, 2, 4, and 6 to rats did not result in increased sensitivity in response to mechanical or thermal stimulation of hind paws, in comparison to Taxol® administration at the same dose level that resulted in neuropathy. Paclitaxel biodisposition was evaluated for two formulations in plasma, liver, lung, brain, spinal cord, skin and muscle of rats after single intravenous dose at 6 mg/kg. The exposure to paclitaxel in brain, spinal cord, muscle, and skin was lower in the L-PTX group compared to Taxol® group. PEGylated liposomes containing paclitaxel were successfully developed and demonstrated reduced neurotoxicity in-vitro in neuronal cells and prevented development of peripheral neuropathy in-vivo. This proof of concept study showed that formulation in nanoparticles is a promising approach for reducing (or preventing) neurotoxicity caused by cancer drugs.

miR-202 modulates the progression of neuropathic pain through targeting RAP1A

Neuropathic pain is a somatosensory disorder which is caused by disease or nerve injury that affects the nervous system. microRNAs (miRNAs) are proved to play crucial roles in the development of neuropathic pain. However, the role of miR-202 in neuropathic pain is still unknown. Sprague-Dawley rats were used for constructing the neuropathic pain model. The expression of miR-202 was determined by quantitative real-time polymerase chain reaction. Potential target gene for miR-202 was measured using bioinformatics methods and Western blot analysis. In this study, we used rats to establish a neuropathic pain model and measured the effect of miR-202 in neuropathic pain. We demonstrated that miR-202 expression was downregulated in the spinal dorsal horn of bilateral sciatic nerve chronic constriction injury (bCCI) rat. However, miR-202 expression was not changed in the dorsal root ganglion, hippocampus, and anterior cingulated cortex of bCCI rat. We identified that RAP1A was a direct target gene of miR-202 in the PC12 cell. RAP1A expression was upregulated in the spinal dorsal horn of bCCI rat. Overexpression of miR-202 could improve the pain threshold for bCCI rats in both hindpaws, indicating that miR-202 overexpression could lighten the pain threshold for model rats. Moreover, RAP1A overexpression increased the pain threshold effect of miR-202 overexpression treated bCCI rats, indicating that miR-202 could lighten the pain threshold through inhibiting RAP1A expression. These data suggested that miR-202 acted pivotal roles in the development of neuropathic pain partly through targeting RAP1A gene.

The Changes of Intrinsic Excitability of Pyramidal Neurons in Anterior Cingulate Cortex in Neuropathic Pain

To find satisfactory treatment strategies for neuropathic pain syndromes, the cellular mechanisms should be illuminated. Central sensitization is a generator of pain hypersensitivity, and is mainly reflected in neuronal hyperexcitability in pain pathway. Neuronal excitability depends on two components, the synaptic inputs and the intrinsic excitability. Previous studies have focused on the synaptic plasticity in different forms of pain. But little is known about the changes of neuronal intrinsic excitability in neuropathic pain. To address this question, whole-cell patch clamp recordings were performed to study the synaptic transmission and neuronal intrinsic excitability 1 week after spared nerve injury (SNI) or sham operation in male C57BL/6J mice. We found increased spontaneous excitatory postsynaptic currents (sEPSC) frequency in layer II/III pyramidal neurons of anterior cingulate cortex (ACC) from mice with neuropathic pain. Elevated intrinsic excitability of these neurons after nerve injury was also picked up, which was reflected in gain of input-output curve, inter-spike interval (ISI), spike threshold and Refractory period (RP). Besides firing rate related to neuronal intrinsic excitability, spike timing also plays an important role in neural information processing. The precision of spike timing measured by standard deviation of spike timing (SDST) was decreased in neuropathic pain state. The electrophysiological studies revealed the elevated intrinsic excitation in layer II/III pyramidal neurons of ACC in mice with neuropathic pain, which might contribute to central excitation.

Neuropathic Pain: Central vs. Peripheral Mechanisms

PURPOSE OF REVIEW

Our goal is to examine the processes-both central and peripheral-that underlie the development of peripherally-induced neuropathic pain (pNP) and to highlight recent evidence for mechanisms contributing to its maintenance. While many pNP conditions are initiated by damage to the peripheral nervous system (PNS), their persistence appears to rely on maladaptive processes within the central nervous system (CNS). The potential existence of an autonomous pain-generating mechanism in the CNS creates significant implications for the development of new neuropathic pain treatments; thus, work towards its resolution is crucial. Here, we seek to identify evidence for PNS and CNS independently generating neuropathic pain signals.

RECENT FINDINGS

Recent preclinical studies in pNP support and provide key details concerning the role of multiple mechanisms leading to fiber hyperexcitability and sustained electrical discharge to the CNS. In studies regarding central mechanisms, new preclinical evidence includes the mapping of novel inhibitory circuitry and identification of the molecular basis of microglia-neuron crosstalk. Recent clinical evidence demonstrates the essential role of peripheral mechanisms, mostly via studies that block the initially damaged peripheral circuitry. Clinical central mechanism studies use imaging to identify potentially self-sustaining infra-slow CNS oscillatory activity that may be unique to pNP patients. While new preclinical evidence supports and expands upon the key role of central mechanisms in neuropathic pain, clinical evidence for an autonomous central mechanism remains relatively limited. Recent findings from both preclinical and clinical studies recapitulate the critical contribution of peripheral input to maintenance of neuropathic pain. Further clinical investigations on the possibility of standalone central contributions to pNP may be assisted by a reconsideration of the agreed terms or criteria for diagnosing the presence of central sensitization in humans.

W. A. H, Lewis RJ, Vetter I. Transcriptomics in pain research: insights from new and old technologies

Physiological and pathological pain involves a complex interplay of multiple cell types and signaling pathways.