The Protective Effect of Bergamot Polyphenolic Fraction (BPF) on Chemotherapy-Induced Neuropathic Pain.

Paclitaxel is a chemotherapeutic drug used for cancer treatment. Chemotherapy-induced peripheral neuropathy (CIPN) is a common major dose-limiting side effect of many chemotherapeutic agents, including paclitaxel. CIPN is accompanied by mechanical and thermal hypersensitivity that resolves within weeks, months, or years after drug termination. To date, there is no available preventive strategy or effective treatment for CIPN due to the fact that its etiology has not been fully explained. It is clear that free radicals are implicated in many neurodegenerative diseases and recent studies have shown the important role of oxidative stress in development of CIPN. Here, we observed how, in rats, the administration of a natural antioxidant such as the bergamot polyphenolic extract (BPF), can play a crucial role in reducing CIPN. Paclitaxel administration induced mechanical allodynia and thermal hyperalgesia, which began to manifest on day seven, and reached its lowest levels on day fifteen. Paclitaxel-induced neuropathic pain was associated with nitration of proteins in the spinal cord including MnSOD, glutamine synthetase, and glutamate transporter GLT-1. This study showed that the use of BPF, probably by inhibiting the nitration of crucial proteins involved in oxidative stress, improved paclitaxel-induced pain behaviors relieving mechanical allodynia, thermal hyperalgesia, thus preventing the development of chemotherapy-induced neuropathic pain.

Antioxidant modulation of sirtuin 3 during acute inflammatory pain: The ROS control.

Oxidative stress induced post-translational protein modifications are associated with the development of inflammatory hypersensitivities. At least 90% of cellular reactive oxygen species (ROS) are produced in the mitochondria, where the mitochondrial antioxidant, manganese superoxide dismutase (MnSOD), is located. MnSOD's ability to reduce ROS is enhanced by the mitochondrial NAD+-dependent deacetylase sirtuin (SIRT3). SIRT3 can reduce ROS levels by deacetylating MnSOD and enhancing its ability to neutralize ROS or by enhancing the transcription of MnSOD and other oxidative stress-responsive genes. SIRT3 can be post-translationally modified through carbonylation which results in loss of activity. The contribution of post-translational SIRT3 modifications in central sensitization is largely unexplored. Our results reveal that SIRT3 carbonylation contributes to spinal MnSOD inactivation during carrageenan-induced thermal hyperalgesia in rats. Moreover, inhibiting ROS with natural and synthetic antioxidants, prevented SIRT3 carbonylation, restored the enzymatic activity of MnSOD, and blocked the development of thermal hyperalgesia. These results suggest that therapeutic strategies aimed at inhibiting post-translational modifications of SIRT3 may provide beneficial outcomes in pain states where ROS have been documented to play an important role in the development of central sensitization.

Plasma N-glycome composition associates with chronic low back pain.

BACKGROUND: Low back pain (LBP) is the symptom of a group of syndromes with heterogeneous underlying mechanisms and molecular pathologies, making treatment selection and patient prognosis very challenging. Moreover, symptoms and prognosis of LBP are influenced by age, gender, occupation, habits, and psychological factors. LBP may be characterized by an underlying inflammatory process. Previous studies indicated a connection between inflammatory response and total plasma N-glycosylation. We wanted to identify potential changes in total plasma N-glycosylation pattern connected with chronic low back pain (CLBP), which could give an insight into the pathogenic mechanisms of the disease. METHODS: Plasma samples of 1128 CLBP patients and 760 healthy controls were collected in clinical centers in Italy, Belgium and Croatia and used for N-glycosylation profiling by hydrophilic interaction ultra-performance liquid chromatography (HILIC-UPLC) after N-glycans release, fluorescent labeling and clean-up. Observed N-glycosylation profiles have been compared with a cohort of 126 patients with acute inflammation that underwent abdominal surgery. RESULTS: We have found a statistically significant increase in the relative amount of high-branched (tri-antennary and tetra-antennary) N-glycan structures on CLBP patients' plasma glycoproteins compared to healthy controls. Furthermore, relative amounts of disialylated and trisialylated glycan structures were increased, while high-mannose and glycans containing bisecting N-acetylglucosamine decreased in CLBP. CONCLUSIONS: Observed changes in CLBP on the plasma N-glycome level are consistent with N-glycosylation changes usually seen in chronic inflammation. GENERAL SIGNIFICANCE: To our knowledge, this is a first large clinical study on CLBP patients and plasma N-glycome providing a new glycomics perspective on potential disease pathology.

Inhibition of Spinal Oxidative Stress by Bergamot Polyphenolic Fraction Attenuates the Development of Morphine Induced Tolerance and Hyperalgesia in Mice.

Citrus Bergamia Risso, commonly known as Bergamot, is a fruit whose Essential Oil and Bergamot Polyphenolic Fraction have numerous medicinal properties. It is also an excellent antioxidant and in this study, for the first time, its potential effect on morphine induced tolerance in mice has been investigated. Our studies revealed that development of antinociceptive tolerance to repeated doses of morphine in mice is consistently associated with increased formation of superoxide, malondialdehyde and tyrosine-nitrated proteins in the dorsal horn of the spinal cord such as the enzyme glutamine synthase. Nitration of this protein is intimately linked to inactivation of its biological function and resulting increase of glutamate levels in the spinal cord. Administration of Bergamot Polyphenolic Fraction (5-50 mg/kg) attenuated tolerance development. This effect was accompanied by reduction of superoxide and malondialdehyde production, prevention of GS nitration, re-establishment of its activity and of glutamate levels. Our studies confirmed the main role of free radicals during the cascade of events induced by prolonged morphine treatment and the co-administration of natural derivatives antioxidant such as Bergamot Polyphenolic Fraction can be an important therapeutic approach to restore opioids analgesic efficacy.

Continuous wound infusion of local anesthetic and steroid after major abdominal surgery: study protocol for a randomized controlled trial.

BACKGROUND: Inflammatory response is one of the key components of pain perception. Continuous infusion (CWI) of local anesthetics has been shown to be effective in controlling pain and reducing postoperative morphine consumption, but the effect of adding a potent anti-inflammatory drug (such as a steroid) has never been addressed. In our study, we want to investigate the effect of CWI with local anesthetic + methylprednisolone on acute and persistent pain, correlating clinical data with biomarkers of inflammation and genetic background. METHODS/DESIGN: After approval by their institutional review board, three hospitals will enroll 120 patients undergoing major abdominal surgery in a randomized, double-blind, phase III study. After a 24-h CWI of ropivacaine 0.2 % + methylprednisolone 1 mg/kg, patients will be randomly assigned to receive either ropivacaine + steroid or placebo for the next 24 h. Then, patient-controlled CWI with only ropivacaine 0.2 % or placebo (according to the group of randomization) is planned after 48 h up to 7 days (bolus 10 ml, lock-out 1 h, maximum dose of 40 ml in 4 h). Morphine equivalent consumption up to 7 days will be analyzed, together with any catheter- or drug-related side effect. Persistent post-surgical pain (PPSP) incidence will also be investigated. Our primary endpoint is analgesic consumption in the first 7 days after surgery; we will evaluate, as secondary endpoints, any catheter- or drug-related side effect, genotype/phenotype correlations between some polymorphisms and postoperative outcome in terms of morphine consumption, development of the inflammatory response, and incidence of PPSP. Finally, we will collect, in a subgroup of patients, wound exudate samples by micro-dialysis, blood samples, and urine samples up to 72 h to investigate local and systemic inflammation and oxidative stress. DISCUSSION: This is a phase III trial to evaluate the safety and efficacy of wound infusion with steroid and local anesthetic. The study is aimed also to evaluate how long this infusion has to be maintained in order to maximize effectiveness. Our data are intended to quantify the amount of ropivacaine and methylprednisolone needed by patients undergoing major abdominal surgery, to be stored in a new nanotechnology device for sustained pain treatment after surgery. We also aim to clarify the roles of inflammatory response, oxidative stress, and genetic background on postoperative and persistent pain after major abdominal surgery. TRIAL REGISTRATION: The trial was registered on ClinicalTrials.gov ( NCT02002663 ) on 24 Oct. 2013.

Targeting the overproduction of peroxynitrite for the prevention and reversal of paclitaxel-induced neuropathic pain.

Chemotherapy-induced peripheral neuropathy (CIPN) accompanied by chronic neuropathic pain is a major dose-limiting side effect of a large number of antitumoral agents including paclitaxel (Taxol). Thus, CIPN is one of most common causes of dose reduction and discontinuation of what is otherwise a life-saving therapy. Neuropathological changes in spinal cord are linked to CIPN, but the causative mediators and mechanisms remain poorly understood. We report that formation of peroxynitrite (PN) in response to activation of nitric oxide synthases and NADPH oxidase in spinal cord contributes to neuropathological changes through two mechanisms. The first involves modulation of neuroexcitatory and proinflammatory (TNF-α and IL-1ß) and anti-inflammatory (IL-10 and IL-4) cytokines in favor of the former. The second involves post-translational nitration and modification of glia-derived proteins known to be involved in glutamatergic neurotransmission (astrocyte-restricted glutamate transporters and glutamine synthetase). Targeting PN with PN decomposition catalysts (PNDCs) not only blocked the development of paclitaxel-induced neuropathic pain without interfering with antitumor effects, but also reversed it once established. Herein, we describe our mechanistic study on the role(s) of PN and the prevention of neuropathic pain in rats using known PNDCs (FeTMPyP(5+) and MnTE-2-PyP(5+)). We also demonstrate the prevention of CIPN with our two new orally active PNDCs, SRI6 and SRI110. The improved chemical design of SRI6 and SRI110 also affords selectivity for PN over other reactive oxygen species (such as superoxide). Our findings identify PN as a critical determinant of CIPN, while providing the rationale toward development of superoxide-sparing and "PN-targeted" therapeutics.

Counter-regulation of opioid analgesia by glial-derived bioactive sphingolipids.

The clinical efficacy of opiates for pain control is severely limited by analgesic tolerance and hyperalgesia. Herein we show that chronic morphine upregulates both the sphingolipid ceramide in spinal astrocytes and microglia, but not neurons, and spinal sphingosine-1-phosphate (S1P), the end-product of ceramide metabolism. Coadministering morphine with intrathecal administration of pharmacological inhibitors of ceramide and S1P blocked formation of spinal S1P and development of hyperalgesia and tolerance in rats. Our results show that spinally formed S1P signals at least in part by (1) modulating glial function because inhibiting S1P formation blocked increased formation of glial-related proinflammatory cytokines, in particular tumor necrosis factor-α, interleukin-1ßα, and interleukin-6, which are known modulators of neuronal excitability, and (2) peroxynitrite-mediated posttranslational nitration and inactivation of glial-related enzymes (glutamine synthetase and the glutamate transporter) known to play critical roles in glutamate neurotransmission. Inhibitors of the ceramide metabolic pathway may have therapeutic potential as adjuncts to opiates in relieving suffering from chronic pain.