Chemotherapy-induced peripheral neuropathy in immunodeficient mice: new useful ready-to-use animal models

Cisplatin, paclitaxel, and bortezomib represent the most employed chemotherapy regimens for the treatment of genitourinary cancers, breast and lung cancers and multiple myeloma. Nevertheless, their clinical use is often associated to the development of peripheral neuropathies characterized mostly by sensory alterations and pain (Argyriou et al., 2012). Several rat models of chemotherapy-induced peripheral neuropathy (CIPN) had been established in the past to describe the mechanisms of its development and pathogenesis. However, only few cancer cell lines induce the development of cancer in the rat, while immunodeficient mice best allowed human cancers xenografts to study at the same time, the antineoplastic and neurotoxic effects of chemotherapy. Here we characterized neuropathic pain, neurophysiological and neuropathological alterations induced by chronic chemotherapy in immunodeficient nude mice. Mice were treated with effective doses of cisplatin (4 mg/Kg, i.p), paclitaxel (80 mg/Kg, i.v) and bortezomib (0.8 mg/Kg, i.v) for a 4-6 weeks period. At the end of the 6th week all chemotherapy regimens determined a significant impairment of neurophysiologic parameters, mechanical allodynia and thermal hypo-or hyperalgesia. Light microscopy analysis of dorsal root ganglia (DRG) showed that bortezomib induced morphological alterations in the sensory neurons and satellite cells as dark inclusions and clear vacuolation throughout the cytoplasm. Moreover, sporadic episodes of neuronal degeneration were evident. DRG of cisplatin-treated animals showed severe neuronal atrophy. Moreover bortezomib induced moderate to severe axonal degeneration of the myelinated fibers in the sciatic nerves. More severe changes were induced by paclitaxel where also areas of fibers loss were frequently observed and rare pathological abnormalities were present in unmyelinated fibers. Similar changes were evident in paclitaxel-treated mice (degeneration at different stage of severity in myelinated fibers, enlargement of Schwann cells, fibers loss and dark inclusions in the unmyelinated fibers). These schedules demonstrated to be effective in mimicking clinical features of painful neuropathies and allows to combine the study of peripheral neurotoxicity of chemotherapy drugs to their anti-tumour activity against cancers of human origin

A new animal model of chemotherapy induced peripheral neurotoxicity: the immune-deficient mouse

Cisplatin, paclitaxel and bortezomib are anticancer drugs widely employed in the treatment of different solid tumours even though peripheral neurotoxicity represents a major limitation in their clinical use. During the last decades many rat and mouse models of chronic chemotherapyinduced peripheral neurotoxicity (CIPN) have been characterized from the clinical, pathological, neurophysiological and behavioural point of view. These models were based on immune-competent animals, however in preclinical oncology immune-deficient mice are mainly used. In this respect, the development of immune-deficient mice models could represent a basis for the concurrent investigation of both anticancer drug efficacy and neurotoxicity in animals implanted with human-derived cancer. Moreover, in the same model, neuroprotective effects and non-interference with anticancer activity could be better studied. In this study we established the feasibility of new immune-deficient murine models of peripheral neurotoxicity induced by three anticancer drugs. Forty-eight athymic nude mice were randomized in 4 groups of 12 animals, three were treated respectively with cisplatin, paclitaxel and bortezomib, and one was left untreated. All animals were followed up for 6 weeks. They were examined at baseline, week 4 and 6 for neurophysiological functions and behavioural tests, whilst morphological and morphometric analysis were performed on dorsal root ganglia (DRG) and peripheral nerves collected after 4 and 6 weeks of treatment. The results of the study demonstrate that athymic nude mice show CIPN features similar to those observed in conventional models even if some differences must be remarked as the prolonged time of treatment required to develop a chronic neuropathy. The characterization of this new mice model of CIPN will allow studies of antineoplastic and neurotoxic effects in the same animal

Morphofunctional characterization of peripheral nerve damage and recovery in sphyngomielinase deficient mice

Mutation of the acid sphingomyelinase (ASM) gene and its reduced enzymatic activity is the main cause of the Type A Niemann-Pick disease. Recent advances demonstrated that ASM is necessary and sufficient to control the formation and release of microvesiscles containing the proinflammatory cytokine interleukin-1β (IL-1β) by glial cells [1]. Since IL-1β modulates the events caused by nerve damage and repair and seems to act as a neuro-modulator between activated glia and neurons [2], the control of its production and secretion might represent a new strategy in nerve regeneration and in the control of neuropathic pain. In this study we used a well-characterized ASM knockout mouse (ASMKO, [3]) to evaluate, through a multimodal approach, the onset and the course of the morphological and functional nerve damage and of neuropathic pain after sciatic nerve crush. Adult (1 and 5 month-old) male ASMKO and age-matched wild-type (WT) mice underwent sciatic nerve crush lesion. Nerve conduction velocity (NCV), walking track analysis followed by ultra-structural and morphometric analysis of sciatic nerves were performed to evaluate the features of nerve damage. Thermal (Plantar test) and mechanical sensitivity (Dynamic Plantar Aesthesiometer apparatus) were used to measure the severity of neuropathic pain. Moreover, the rotarod test completed the analysis as an indicator of motor impairment. One or two months after the nerve crush motor functional recovery was similar in WT and KO mice and the NCV measures performed in the sciatic nerve demonstrated a moderate and progressive improvement of nerve function. The results of the morphological examination confirmed the expected course of nerve recovery, but also demonstrated defective nerve regeneration, particularly evident in older, but already present in younger ASMKO mice. Behavioral tests suggested that the mutated phenotype in ASMKO might have an effect on the onset and development of mechanical and thermal hyperalgesia after nerve crush in both 1 - month and 5 - months - old groups. In conclusion, these data suggest a possible role for ASM-related microvesicles in nerve regeneration and suggest that targeting the IL-1β production and release may represent a new therapeutic strategy for the treatment of nerve damage and neuropathic pain

Oxaliplatin-induced peripheral neurotoxicity: morphological characterization in different mouse strains

Oxaliplatin is one of the most effective anticancer drug, particularly employed in the treatment of colorectal cancer, but one of the major limitation in its use is peripheral neurotoxicity. Oxaliplatin induced peripheral neurotoxicity (OIPN) has a high incidence and is frequently long lasting or permanent. Neuropathy is characterized by distal sensory impairment initially in the legs, then extending to the arms. A prominent manifestation of sensitive damage is ataxia. Besides chronic neurotoxicity, many patients experience an acute, rapidly developing cold-induced sensory neuropathy, usually resolving within one week. OIPN clinical manifestations reflect the involvement of dorsal root ganglia (DRG) as primary target of the drug toxicity. Although this assumption is largely accepted and some pathogenetic hypothesis have been proposed, mechanisms at the basis of OIPN need to be clearly defined. OIPN may vary in frequency and severity among different cancer patients despite equal treatment schedules. A genetic susceptibility for more severe oxaliplatin-induced peripheral neurotoxicity (OIPN) has been suggested but never confirmed. Therefore we designed a study to assess the phenotypic differences induced by oxaliplatin treatment in six different mice strains (Balb c, AJ, C57Bl6, FVB, DBA, CD1) aiming at identifying the more and less severely affected. Animals were treated with OHP 3.5 mg/Kg/iv twice weekly x 4 weeks and evaluated before and after treatment. In all strains we performed a multimodal characterization of its neurotoxicity through morphological and morphometrical assessment in caudal nerve and DRG at light and electron microscopy, intra-epidermal nerve fibers density quantification, evaluation of mechanical and cold allodynia/hypoaesteshesia, caudal and digital nerve conduction velocity, activity of wide dynamic range (WDR) neurons of the spinal dorsal horn. Our preliminary data suggest that all the strains show signs of OIPN but not the same modifications in the parameters examined. We will show these results with particular attention to morphological data. This study suggests that genetic variability might have a role in the type and severity of OHP-induced peripheral damage

Reply to a Comment Paper on the Published Paper by Canta, A. et al: “Calmangafodipir Reduces Sensory Alterations and Prevents Intraepidermal Nerve Fibers Loss in a Mouse Model of Oxaliplatin Induced Peripheral Neurotoxicity”—Antioxidants 2020, 9, 594

The comments sent by Stehr, Lundstom and Karlsson with reference to our article “Calmangafodipir reduces sensory alterations and prevents intraepidermal nerve fiber loss in a mouse model of oxaliplatin-induced peripheral neurotoxicity“ are very interesting, since they suggest possible mechanisms of action of the compound, which might contribute to its protective action [...

Multimodal Comparison of Diabetic Neuropathy in Aged Streptozotocin-Treated Sprague–Dawley and Zucker Diabetic Fatty Rats

The development and progression of diabetic polyneuropathy (DPN) are due to multiple mechanisms. The creation of reliable animal models of DPN has been challenging and this issue has not yet been solved. However, despite some recognized differences from humans, most of the current knowledge on the pathogenesis of DPN relies on results achieved using rodent animal models. The simplest experimental DPN model reproduces type 1 diabetes, induced by massive chemical destruction of pancreatic beta cells with streptozotocin (STZ). Spontaneous/transgenic models of diabetes are less frequently used, mostly because they are less predictable in clinical course, more expensive, and require a variable time to achieve homogeneous metabolic conditions. Among them, Zucker diabetic fatty (ZDF) rats represent a typical type 2 diabetes model. Both STZ-induced and ZDF rats have been extensively used, but only very few studies have compared the long-term similarities and differences existing between these two models. Moreover, inconsistencies have been reported regarding several aspects of short-term in vivo studies using these models. In this study, we compared the long-term course of DPN in STZ-treated Sprague–Dawley and ZDF rats with a multimodal set of readout measures

Bortezomib-induced painful peripheral neuropathy: an electrophysiological, behavioral, morphological and mechanistic study in the mouse.

Bortezomib is the first proteasome inhibitor with significant antineoplastic activity for the treatment of relapsed/refractory multiple myeloma as well as other hematological and solid neoplasms. Peripheral neurological complications manifesting with paresthesias, burning sensations, dysesthesias, numbness, sensory loss, reduced proprioception and vibratory sensitivity are among the major limiting side effects associated with bortezomib therapy. Although bortezomib-induced painful peripheral neuropathy is clinically easy to diagnose and reliable models are available, its pathophysiology remains partly unclear. In this study we used well-characterized immune-competent and immune-compromised mouse models of bortezomib-induced painful peripheral neuropathy. To characterize the drug-induced pathological changes in the peripheral nervous system, we examined the involvement of spinal cord neuronal function in the development of neuropathic pain and investigated the relevance of the immune response in painful peripheral neuropathy induced by bortezomib. We found that bortezomib treatment induced morphological changes in the spinal cord, dorsal roots, dorsal root ganglia (DRG) and peripheral nerves. Neurophysiological abnormalities and specific functional alterations in Aδ and C fibers were also observed in peripheral nerve fibers. Mice developed mechanical allodynia and functional abnormalities of wide dynamic range neurons in the dorsal horn of spinal cord. Bortezomib induced increased expression of the neuronal stress marker activating transcription factor-3 in most DRG. Moreover, the immunodeficient animals treated with bortezomib developed a painful peripheral neuropathy with the same features observed in the immunocompetent mice. In conclusion, this study extends the knowledge of the sites of damage induced in the nervous system by bortezomib administration. Moreover, a selective functional vulnerability of peripheral nerve fiber subpopulations was found as well as a change in the electrical activity of wide dynamic range neurons of dorsal horn of spinal cord. Finally, the immune response is not a key factor in the development of morphological and functional damage induced by bortezomib in the peripheral nervous system

Bevacizumab prevented and restored peripheral nerve functions in diabetic rats.

<p>Control and STZ-diabetic rats were treated with bevacizumab according to the prevention (A, B, C) or therapeutic (D, E, F) schedule. (A) Bevacizumab prevented in a dose-dependent fashion thermal hypoalgesia, (B) mechanical threshold decrease and (C) nerve conduction velocity decrease in diabetic rats. In the therapeutic schedule, bevacizumab restored (D) thermal hypoalgesia (E) mechanical threshold and (F) nerve conduction velocity decrease in diabetic rats. Data are expressed as mean±SEM (<i>n</i> = 8 animals per group) *p<0.05 vs controls; **p<0.01 vs controls; ****p<0.001 vs controls; #*p<0.05 vs STZ; ##p<0.01 vs STZ.</p