Anti-allodynic and anti-inflammatory effects of 17α-hydroxyprogesterone caproate in oxaliplatin-induced peripheral neuropathy

Current understanding of the molecular mechanisms of chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is the most common off-target adverse effects caused by various chemotherapeutic agents, such as cisplatin, oxaliplatin, paclitaxel, vincristine and bortezomib. CIPN is characterized by a substantial loss of primary afferent sensory axonal fibers leading to sensory disturbances in patients. An estimated of 19-85% of patients developed CIPN during the course of chemotherapy. The lack of preventive measures and limited treatment options often require a dose reduction or even early termination of life-saving chemotherapy, impacting treatment efficacy and patient survival. In this Review, we summarized the current understanding on the pathogenesis of CIPN. One prominent change induced by chemotherapeutic agents involves the disruption of neuronal cytoskeletal architecture and axonal transport dynamics largely influenced by the interference of microtubule stability in peripheral neurons. Due to an ineffective blood-nerve barrier in our peripheral nervous system, exposure to some chemotherapeutic agents causes mitochondrial swelling in peripheral nerves, which lead to the opening of mitochondrial permeability transition pore and cytochrome c release resulting in degeneration of primary afferent sensory fibers. The exacerbated nociceptive signaling and pain transmission in CIPN patients is often linked the increased neuronal excitability largely due to the elevated expression of various ion channels in the dorsal root ganglion neurons. Another important contributing factor of CIPN is the neuroinflammation caused by an increased infiltration of immune cells and production of inflammatory cytokines. In the central nervous system, chemotherapeutic agents also induce neuronal hyperexcitability in the spinal dorsal horn and anterior cingulate cortex leading to the development of central sensitization that causes CIPN. Emerging evidence suggests that the change in the composition and diversity of gut microbiota (dysbiosis) could have direct impact on the development and progression of CIPN. Collectively, all these aspects contribute to the pathogenesis of CIPN. Recent advances in RNA-sequencing offer solid platform for in silico drug screening which enable the identification of novel therapeutic agents or repurpose existing drugs to alleviate CIPN, holding immense promises for enhancing the quality of life for cancer patients who undergo chemotherapy and improve their overall treatment outcomes.

Mitotherapy prevents peripheral neuropathy induced by oxaliplatin in mice

Oxaliplatin (OXA) is an antineoplastic agent used for the treatment of cisplatin-resistant tumours, presenting lower incidence of nephrotoxicity and myelotoxicity than other platinum-based drugs. However, OXA treatment is highly associated with painful peripheral neuropathy, a well-known and relevant side effect caused by mitochondrial dysfunction. The transfer of functional exogenous mitochondria (mitotherapy) is a promising therapeutic strategy for mitochondrial diseases. We investigated the effect of mitotherapy on oxaliplatin-induced painful peripheral neuropathy (OIPN) in male mice. OIPN was induced by i.p. injections of oxaliplatin (3 mg/kg) over 5 consecutive days. Mechanical (von Frey test) and cold (acetone drop test) allodynia were evaluated between 7 and 17 days after the first OXA treatment. Mitochondria was isolated from donor mouse livers and mitochondrial oxidative phosphorylation was assessed with high resolution respirometry. After confirming that the isolated mitochondria were functional, the organelles were administered at the dose of 0.5 mg/kg of mitochondrial protein on days 1, 3 and 5. Treatment with OXA caused both mechanical and cold allodynia in mice that were significant 7 days after the initial injection of OXA and persisted for up to 17 days. Mitotherapy significantly prevented the development of both sensory alterations, and attenuated body weight loss induced by OXA. Mitotherapy also prevented spinal cord ERK1/2 activation, microgliosis and the increase in TLR4 mRNA levels. Mitotherapy prevented OIPN by inhibiting neuroinflammation and the consequent cellular overactivity in the spinal cord, presenting a potential therapeutic strategy for pain management in oncologic patients undergoing OXA treatment.

Changes in the expression of endocannabinoid system components in an experimental model of chemotherapy-induced peripheral neuropathic pain: Evaluation of sex-related differences

Chemotherapy-induced neuropathic pain is a serious clinical problem and one of the major side effects in cancer treatment. The endocannabinoid system (ECS) plays a crucial role in regulating pain neurotransmission, and changes in the expression of different components of the ECS have been reported in experimental models of persistent pain. In addition, sex differences have been observed in ECS regulation and function. The aim of our study was to evaluate whether administration of oxaliplatin, a neurotoxic antineoplastic agent, induced changes in the expression of ECS components in peripheral and central stations of the pain pathway, and if those changes exhibited sexual dimorphism. Adult male and female rats were injected with oxaliplatin or saline, and mechanical and cold hypersensitivity and allodynia were evaluated using Von Frey and Choi Tests. The mRNA levels corresponding to cannabinoid receptors (CB1, CB2), cannabinoid-related receptors (GPR55, 5HT1A, TRPV1) and to the main enzymes involved in the synthesis (DAGL, DAGL, NAPE-PLD) and degradation (MGL, FAAH) of endocannabinoids were assessed in lumbar dorsal root ganglia (DRGs) and spinal cord by using real time RT-PCR. In addition, the levels of the main endocannabinoids, 2-arachidonoylglycerol (2-AG) and anandamide (AEA), were evaluated using commercial ELISA kits. Oxaliplatin administration induced the development of mechanical and cold hypersensitivity and allodynia in male and female animals. Oxaliplatin also induced early and robust changes in the expression of several components of the ECS in DRGs. A marked upregulation of CB1, CB2, 5HT1A and TRPV1 was detected in both sexes. Interestingly, while DAGL mRNA levels remained unchanged, DAGL was downregulated in male and upregulated in female rats. Finally, MGL and NAPE-PLD showed increased levels only in male animals, while FAAH resulted upregulated in both sexes. In parallel, reduced 2-AG and AEA levels were detected in DRGs from male or female rats, respectively. In the lumbar spinal cord, only TRPV1 mRNA levels were found to be upregulated in both sexes. Our results reveal previously unreported changes in the expression of cannabinoid receptors, ligands and enzymes occurring mainly in the peripheral nervous system and displaying certain sexual dimorphism. These changes may contribute to the physiopathology of oxaliplatin-induced neuropathic pain in male and female rats. A better understanding of these dynamic changes will facilitate the development of mechanism- and sex-specific approaches to optimize the use of cannabinoid-based medicines for the treatment of chemotherapy-induced pain.

2-Bromopalmitate decreases spinal inflammation and attenuates oxaliplatin-induced neuropathic pain via reducing Drp1-mediated mitochondrial dysfunction

Oxaliplatin (OXA) is a third-generation platinum compound with clinical activity in multiple solid tumors. Due to the repetition of chemotherapy cycle, OXA-induced chronic neuropathy presenting as paresthesia and pain. This study explored the neuropathy of chemotherapy pain and investigated the analgesic effect of 2-bromopalmitate (2-BP) on the pain behavior of OXA-induced rats. The chemotherapy pain rat model was established by the five consecutive administration of OXA (intraperitoneal, 4 mg/kg). After the establishment of OXA-induced rats, the pain behavior test, inflammatory signal analysis and mitochondrial function measurement were conducted. OXA-induced rats exhibited mechanical allodynia and spinal inflammatory infiltration. Our fluorescence and western blot analysis revealed spinal astrocytes were activated in OXA rats with up-regulation of astrocytic markers. In addition, NOD-, LRR- and pyrin domain-containing 3 (NLRP3) inflammasome mediated inflammatory signal cascade was also activated. Inflammation was triggered by dysfunctional mitochondria which represented by increase in cyclooxygenase-2 (COX-2) level and manganese superoxide dismutase (Mn-SOD) activity. Intrathecally injection of 2-BP significantly attenuated dynamin-related protein 1 (Drp1) mediated mitochondrial fission, recovered mitochondrial function, suppressed NLRP3 inflammasome cascade, and consequently decreased mechanical pain sensitivity. For cell research, 2-BP treatment significantly reversed tumor necrosis factor-α (TNF-α) induced mitochondria membrane potential deficiency and high reactive oxygen species (ROS) level. These findings indicate 2-BP decreases spinal inflammation and relieves OXA-induced neuropathic pain via reducing Drp1-mediated mitochondrial dysfunction.

Sex-related differences in oxaliplatin-induced changes in the expression of transient receptor potential channels and their contribution to cold hypersensitivity

Transient receptor potential (TRP) channels are involved in the development of oxaliplatin-induced neuropathic pain, a frequent and debilitating side effect of cancer therapy. Here we explored whether oxaliplatin-induced changes in the expression of TRP channels, as well as the development of pain-related behaviours, differed between male and female animals. Adult rats were injected with oxaliplatin or saline and mechanical and cold allodynia were evaluated using Von Frey and Choi Tests. The mRNA levels of TRPV1, TRPM8 and TRPA1 were assessed in lumbar ganglia and spinal cord by using real time RT-PCR. Oxaliplatin administration induced mechanical and cold hypersensitivity and allodynia in both sexes, with more severe responses to cold stimulation detected in females. Oxaliplatin also induced a significant increase in the expression of TRPV1, TRPM8 and TRPA1 in lumbar dorsal root ganglia. Interestingly, while TRPV1 and TRPA1 upregulation showed no sex difference, the increase in TRPM8 mRNA levels was more pronounced in female ganglia, correlating with the increased sensitivity to innocuous cold stimuli observed in females. TRPV1 and TRPM8 were also found to be upregulated in the spinal cord of animals of both sexes. Our results reveal previously undescribed changes in the expression of TRP channels occurring in peripheral ganglia and spinal cord of both male and female oxaliplatin-treated animals, with some of these changes exhibiting sex-related differences that could underlie the development of sex-specific patterns of pain-related behaviours.

Emerging Approaches for the Management of Chemotherapy-Induced Peripheral Neuropathy (CIPN): Therapeutic Potential of the C5a/C5aR Axis

Chemotherapy-induced peripheral neuropathy (CIPN) is the most common neurologic complication of chemotherapy, resulting in symptoms like pain, sensory loss, and numbness in the hands and feet that cause lots of uneasiness in patients with cancer. They often suffer from pain so severe that it interrupts the treatment, thus invalidating the entire chemotherapy-based healing process, and significantly reducing their quality of life. In this paper, we underline the role of the complement system in CIPN, highlighting the relevance of the C5a fragment and its receptor C5aR1, whose activation is thought to be involved in triggering a cascade of events that can lead to CIPN onset. Recent experimental data showed the ability of docetaxel and paclitaxel to specifically bind and activate C5aR1, thus shining light on one of the molecular mechanisms by which taxanes may activate a cascade of events leading to neuropathy. According to these new evidence, it was possible to suggest new mechanisms underlying the pathophysiology of CIPN. Hence, the C5a/C5aR1 axis may represent a new target for CIPN treatment, and the use of C5aR1 inhibitors can be proposed as a potential new therapeutic option to manage this high unmet medical need.

17-α Hydroxyprogesterone Caproate Immunology, a Special Focus on Preterm Labor, Preeclampsia, and COVID-19

17-α hydroxyprogesterone caproate (17-OHPC) could alter the immune response and inflammation, specifically affecting the risk of preterm labor and preeclampsia. However, the exact immune and inflammatory effects of 17-OHPC remain hard to be identified. The current literature on 17-OHPC immune effects is limited and more research is needed to identify these mechanistic pathways. Further, coronavirus disease 2019 (COVID-19) infection in pregnancy involves heightened immune response, widespread inflammation and high rates of preterm labor and preeclampsia. Since the pathogenesis of preterm labor, preeclampsia and COVID-19 involves inflammation and altered immune response, it is important to explore the possible immune effects of 17-OHPC in pregnant women with COVID-19. This commentary article will explain the immune effects of 17-OHPC and their implications in preterm labor, preeclampsia and COVID-19.

Targeting strategies for oxaliplatin-induced peripheral neuropathy: clinical syndrome, molecular basis, and drug development

Oxaliplatin (OHP)-induced peripheral neurotoxicity (OIPN) is a severe clinical problem and potentially permanent side effect of cancer treatment. For the management of OIPN, accurate diagnosis and understanding of significant risk factors including genetic vulnerability are essential to improve knowledge regarding the prevalence and incidence of OIPN as well as enhance strategies for the prevention and treatment of OIPN. The molecular mechanisms underlying OIPN are complex, with multi-targets and various cells causing neuropathy. Furthermore, mechanisms of OIPN can reinforce each other, and combination therapies may be required for effective management. However, despite intense investigation in preclinical and clinical studies, no preventive therapies have shown significant clinical efficacy, and the established treatment for painful OIPN is limited. Duloxetine is the only agent currently recommended by the American Society of Clinical Oncology. The present article summarizes the most recent advances in the field of studies on OIPN, the overview of the clinical syndrome, molecular basis, therapy development, and outlook of future drug candidates. Importantly, closer links between clinical pain management teams and oncology will advance the effectiveness of OIPN treatment, and the continued close collaboration between preclinical and clinical research will facilitate the development of novel prevention and treatments for OIPN.

Neuroinflammatory Process Involved in Different Preclinical Models of Chemotherapy-Induced Peripheral Neuropathy

Peripheral neuropathies are characterized by nerves damage and axonal loss, and they could be classified in hereditary or acquired forms. Acquired peripheral neuropathies are associated with several causes, including toxic agent exposure, among which the antineoplastic compounds are responsible for the so called Chemotherapy-Induced Peripheral Neuropathy (CIPN). Several clinical features are related to the use of anticancer drugs which exert their action by affecting different mechanisms and structures of the peripheral nervous system: the axons (axonopathy) or the dorsal root ganglia (DRG) neurons cell body (neuronopathy/ganglionopathy). In addition, antineoplastic treatments may affect the blood brain barrier integrity, leading to cognitive impairment that may be severe and long-lasting. CIPN may affect patient quality of life leading to modification or discontinuation of the anticancer therapy. Although the mechanisms of the damage are not completely understood, several hypotheses have been proposed, among which neuroinflammation is now emerging to be relevant in CIPN pathophysiology. In this review, we consider different aspects of neuro-immune interactions in several CIPN preclinical studies which suggest a critical connection between chemotherapeutic agents and neurotoxicity. The features of the neuroinflammatory processes may be different depending on the type of drug (platinum derivatives, taxanes, vinca alkaloids and proteasome inhibitors). In particular, recent studies have demonstrated an involvement of the immune response (both innate and adaptive) and the stimulation and secretion of mediators (cytokines and chemokines) that may be responsible for the painful symptoms, whereas glial cells such as satellite and Schwann cells might contribute to the maintenance of the neuroinflammatory process in DRG and axons respectively. Moreover, neuroinflammatory components have also been shown in the spinal cord with microglia and astrocytes playing an important role in CIPN development. Taking together, better understanding of these aspects would permit the development of possible strategies in order to improve the management of CIPN.

Therapeutic Agents for Oxaliplatin-Induced Peripheral Neuropathy; Experimental and Clinical Evidence

Oxaliplatin is an essential drug in the chemotherapy of colorectal, gastric, and pancreatic cancers, but it frequently causes peripheral neuropathy as a dose-limiting factor. So far, animal models of oxaliplatin-induced peripheral neuropathy have been established. The mechanisms of development of neuropathy induced by oxaliplatin have been elucidated, and many drugs and agents have been proven to have neuroprotective effects in basic studies. In addition, some of these drugs have been validated in clinical studies for their inhibitory effects on neuropathy. In this review, we summarize the basic and clinical evidence for the therapeutic effects of oxaliplatin. In basic research, there are many reports of neuropathy inhibitors that target oxidative stress, inflammatory response, sodium channel, transient receptor potential (TRP) channel, glutamate nervous system, and monoamine nervous system. Alternatively, very few drugs have clearly demonstrated the efficacy for oxaliplatin-induced peripheral neuropathy in clinical trials. It is important to activate translational research in order to translate basic research into clinical research.

Therapeutic Agents for Oxaliplatin-Induced Peripheral Neuropathy; Experimental and Clinical Evidence

Oxaliplatin is an essential drug in the chemotherapy of colorectal, gastric, and pancreatic cancers, but it frequently causes peripheral neuropathy as a dose-limiting factor. So far, animal models of oxaliplatin-induced peripheral neuropathy have been established. The mechanisms of development of neuropathy induced by oxaliplatin have been elucidated, and many drugs and agents have been proven to have neuroprotective effects in basic studies. In addition, some of these drugs have been validated in clinical studies for their inhibitory effects on neuropathy. In this review, we summarize the basic and clinical evidence for the therapeutic effects of oxaliplatin. In basic research, there are many reports of neuropathy inhibitors that target oxidative stress, inflammatory response, sodium channel, transient receptor potential (TRP) channel, glutamate nervous system, and monoamine nervous system. Alternatively, very few drugs have clearly demonstrated the efficacy for oxaliplatin-induced peripheral neuropathy in clinical trials. It is important to activate translational research in order to translate basic research into clinical research.

Therapeutic Agents for Oxaliplatin-Induced Peripheral Neuropathy; Experimental and Clinical Evidence

Oxaliplatin is an essential drug in the chemotherapy of colorectal, gastric, and pancreatic cancers, but it frequently causes peripheral neuropathy as a dose-limiting factor. So far, animal models of oxaliplatin-induced peripheral neuropathy have been established. The mechanisms of development of neuropathy induced by oxaliplatin have been elucidated, and many drugs and agents have been proven to have neuroprotective effects in basic studies. In addition, some of these drugs have been validated in clinical studies for their inhibitory effects on neuropathy. In this review, we summarize the basic and clinical evidence for the therapeutic effects of oxaliplatin. In basic research, there are many reports of neuropathy inhibitors that target oxidative stress, inflammatory response, sodium channel, transient receptor potential (TRP) channel, glutamate nervous system, and monoamine nervous system. Alternatively, very few drugs have clearly demonstrated the efficacy for oxaliplatin-induced peripheral neuropathy in clinical trials. It is important to activate translational research in order to translate basic research into clinical research.

Physiopathological Role of Neuroactive Steroids in the Peripheral Nervous System

Peripheral neuropathy (PN) refers to many conditions involving damage to the peripheral nervous system (PNS). Usually, PN causes weakness, numbness and pain and is the result of traumatic injuries, infections, metabolic problems, inherited causes, or exposure to chemicals. Despite the high prevalence of PN, available treatments are still unsatisfactory. Neuroactive steroids (i.e., steroid hormones synthesized by peripheral glands as well as steroids directly synthesized in the nervous system) represent important physiological regulators of PNS functionality. Data obtained so far and here discussed, indeed show that in several experimental models of PN the levels of neuroactive steroids are affected by the pathology and that treatment with these molecules is able to exert protective effects on several PN features, including neuropathic pain. Of note, the observations that neuroactive steroid levels are sexually dimorphic not only in physiological status but also in PN, associated with the finding that PN show sex dimorphic manifestations, may suggest the possibility of a sex specific therapy based on neuroactive steroids.

Management of Oxaliplatin-Induced Peripheral Sensory Neuropathy

Oxaliplatin-induced peripheral neurotoxicity (OIPN) is a severe and potentially permanent side effect of cancer treatment affecting the majority of oxaliplatin-treated patients, mostly with the onset of acute symptoms, but also with the establishment of a chronic sensory loss that is supposed to be due to dorsal root ganglia neuron damage. The pathogenesis of acute as well as chronic OIPN is still not completely known, and this is a limitation in the identification of effective strategies to prevent or limit their occurrence. Despite intense investigation at the preclinical and clinical levels, no treatment can be suggested for the prevention of OIPN, and only limited evidence for the efficacy of duloxetine in the treatment setting has been provided. In this review, ongoing neuroprotection clinical trials in oxaliplatin-treated patients will be analyzed with particular attention paid to the hypothesis leading to the study, to the trial strengths and weaknesses, and to the outcome measures proposed to test the efficacy of the therapeutic approach. It can be concluded that (1) prevention and treatment of OIPN still remains an important and unmet clinical need, (2) further, high-quality research is mandatory in order to achieve reliable and effective results, and (3) dose and schedule modification of OHP-based chemotherapy is currently the most effective approach to limit the severity of OIPN.