Department of Pharmacology of Pain

General description
The Department of Pharmacology of Pain is devoted to studying the initiation and maintenance of pain processes, with particular emphasis on neuropathic pain, which occurs after peripheral nerve injuries due to lesions, cancer, diabetes, multiple sclerosis, hypoxia. This type of pain cannot be relieved by typical painkillers, therefore it is often considered a disorder without prospect of significant improvement. Despite numerous clinical and experimental studies, the molecular mechanisms involved in the development of pain is still not fully understood.
The purpose of our research is to identify alterations in endogenous opioid system homeostasis, which seem to be an important factor in the development of chronic pain. An activation of endogenous analgesic systems in response to the nervous system damage triggers homeostatic mechanisms and in consequence leads to an excessive activity of pro-nociceptive systems. Our research aims to determine various pro-nociceptive peptide pathways which contribute to the development of neuropathy.
Studies using both gene expression profiling and protein analysis indicate that neuropathic pain involves strong activation of many neuronal genes as well as genes related to the immune cell response, including microglial activation. This is an important area of research because there is no data evaluating the efficacy of combined use of opioids and inhibitors of microglia or proinflammatory factors, such as IL-1beta, CCL2, CCL5, as well as blockers of intracellular signaling pathways NF-kB, ERK1/2 and p38MAPK, in the treatment of neuropathic pain. Our studies also involve the search for new targets which could be used to develop more effective treatments of diabetic neuropathy. The results of these experiments demonstrate that modulation of neuroimmunological pathways, by administration of pentoxifylline (an inhibitor of inflammatory cytokines), minocycline (p38MAPK inhibitor), parthenolide (NF-κB inhibitor), U0126 (ERK1/2 inhibitor), SB203580 (p38MAPK inhibitor) PD98059 (MAPKK inhibitor), attenuates the development of neuropathic pain but may also augment the efficacy of opioids. We hope that the results of our research would provide an experimental basis for future clinical use of combination therapy employing opioid analgesics and glial inhibitors or other substances modulating the synthesis or action of proinflammatory factors, in order to increase the analgesic efficacy of drugs in the treatment of neuropathic pain.

Research methods

The most important recent scientific discoveries

This paper clarifies attenuated efficacy of opioid drugs in the treatment of neuropathic pain by demonstrating the presence of MOP and KOP receptors and the absence of the opioid DOP receptor on microglial cells. This finding may explain why DOP receptor agonists are inefficient in the treatment of neuropathic pain, as opposed to the attenuated effects of drugs acting through the other two opioid receptors and indicates future directions for the search for novel analgesics.

It has been shown that pro-inflammatory cytokines derived from glial cells activated by the nervous system damage play an important role in the neurotoxic effects of dynorphin in the neuropathic pain model. Inhibition of this activity significantly attenuates adverse effects of dynorphin, which is one of the factors involved in the neuropathic pain development.

More publications
  • New strategies in neuropathic pain pharmacotherapy based on the modulation of the functions of chemokine receptors CCR2 and CCR5, Klaudia Kwiatkowski, MSc
    The International Association for the Study of Pain defines pain as an unpleasant sensory and emotional experience connected with actual or potential tissue injury. We can talk about chronicity of pain when it lasts or recurs over the period longer than 3 months. It is estimated that currently it affects approximately 20% of adult Europeans, creating a serious clinical problem. When chronic pain results from a lesion or disease of the nervous system, we can talk about neuropathic pain characterized by allodynia, pain appearing due to a stimulus which normally does not induce pain and hyperalgesia, hypersensitivity to a nociceptive stimulus. Because of the wide range of accompanying symptoms such as sleeplessness, anxiety, or even depression, neuropathic pain has a negative influence on all aspects of patients’ life, significantly lowering its quality. However, the therapy of neuropathic pain, despite numerous basic and clinical studies, remains extremely difficult, mainly due to the complex and still insufficiently understood mechanism underlying its development. Recent studies indicate that interactions occurring between neurons, glia and immune cells may be crucial for the generation and maintenance of neuropathic pain. It has been suggested that this processes are largely mediated by chemokines. In our current project we are intending to analyse the changes in the level of numerous intracellular factors and cytokines, especially interleukins and chemokines, involved in a pathological pain transmission after peripheral nerves injury. We would like to focus on two important chemokine receptors, by which these endogenous nociceptive factors may act, namely CCR2 and CCR5. The latest data indicates that their expression is changed under neuropathic pain, especially on neurons and glial cells. It is known that activated glia is an important source of pronociceptive mediators and inhibiting their activation brings beneficial effects in pain therapy. We are planning to determine whether the blocking of these two receptors can inhibit the secretion of pronociceptive factors involved in the formation of neuropathic pain and promote the release of antinociceptive factors contributing to the attenuation of painful symptoms. Moreover, we are planning to compare if these potential beneficial effects are enhanced in case of a simultaneous blocking of these two chemokine receptors. We would like to check if a direct inhibition of nociceptive chemokines, such as CCL2, CCL7 and CCL8, may have even more beneficial impact under neuropathic pain. The other reason for the lack of an effective neuropathic pain therapy is the fact that commonly used opioids lose their effectiveness in painful neuropathy. Thus, current studies are beginning to search for a successful combination drug therapy, which would allow for obtaining stronger analgesia without dangerous adverse effects. Previous reports suggest that some chemokines influence opioid-induced analgesia, and blocking their action by selective chemokine receptors antagonists can serve as applicable co-analgesics effective in a neuropathic pain therapy. In the light of such promising results, we would like to examine if a dual antagonist of CCR2 and CCR5, cenicriviroc, or an inhibitor of the CCL2, CCL7, and CCL8 release, bindarit, may enhance the analgesic potency of opioids used in clinic (e.g. morphine, buprenorphine, tramadol and/or oxycodone). We wish to compare if the eventual effects extend the effects of selective antagonists, such as maraviroc (CCR5 antagonist) or RS504393 (CCR2 antagonist). What is interesting, some of the substances used in our project have already been applied in clinic (e.g. maraviroc) or included in the advanced phases of clinical trials (e.g. cenicriviroc, bindarit). However, none of them is used in patients suffering from neuropathic pain. Furthermore, we believe that the translational character of basic studies is very important, thus we find it interesting to study the effects of the examined drugs in different routes of administration. In this way, we would be able to choose the most beneficial application for patients. We are planning to publish the results obtained in this project in high impact journals and present them at conferences. Moreover, all results will become the foundation for a PhD dissertation prepared by the project coordinator. Hopefully, the results obtained in this project will allow us to expand our knowledge about the processes underlying neuropathic pain development and propose new pharmacological targets for innovative and effective therapies of neuropathic pain.
  • PRELUDIUM 12 2016/23/N/NZ7/00356 Determination of the mechanisms and potential targets for neuropathic pain therapy by investigating pharmacological interactions occurring between substances that modulates glial cells activity and opioid analgesics., Anna Piotrowska-Murzyn, PhD
    PURPOSE OF THE RESEARCH: Currently used methods of treating neuropathic pain are unsatisfactory. Establishing an effective therapy which could improve the quality of life of those who suffer from this kind of pain remains a huge challenge. Despite many years of research in this field, the mechanism of formation and maintenance of neuropathic pain is still not fully understood. Recent studies, including ours, indicate that glia are the cells which play a vital role in the development of neuropathy. The aim of the proposed project is a thorough examination the role of GPCRs such as chemokine/opioid receptors located on the surface of glial cells. Moreover, we would like to analyze the changes in the level of endogenous factors which initiate and regulate the development of neuropathy and which occur as a consequence of the sciatic nerve damage. Importantly, we are planning to use primary cultures of microglia and astrocytes, which will hopefully provide us with a better understanding of the role of these cells in the pathology of pain. A biochemical analysis will be conducted in vivo and in vitro. These tests will allow us to determine the changes in the level of receptors (CCR5, CXCR3, μ) and algesic mediators (e.g. CCL2-5,11,13,21, CXCL4,9-11, IL-1β, IL-6, IL-18) which contribute to the formation of neuropathic pain as well as endogenous analgesic mediators (IL-1RA, IL-18BP, IL-10). In addition, the project will involve the pharmacological pain modulation by the use of antagonists of chemokine receptors and inhibitors of intracellular pathways (p38MAPK, ERK1/2 among others) and the evaluation of their analgesic activity as well as the effect on the balance between pro- and anti-nociceptive factors. Minocycline, maraviroc and parthenolide are now used in the clinic, but not in the treatment of neuropathic pain. Their incorporation in our research can provide new evidence for their therapeutic effects. We are also planning to combine the administration of conventionally used analgesic opioids (for example tramadol) with selected immunomodulatory substances characterized by the highest analgesic potential. This can contribute to the establishing of foundations for a new and effective combination therapy of neuropathic pain. The results obtained in the research will bring a better understanding of the neuroimmunological bases of the formation of neuropathic pain. On the other hand, the results will enable us to evaluate the effectiveness of pharmacological substances used in relieving pain.RESEARCH HYPOTHESIS:1. In a rat/mouse model of neuropathic pain: 1.1 Chemokine receptor antagonists and inhibitors of intracellular pathways reduce pain by restoring the balance between pro- and anti-nociceptive factors. 1.2 Combined administration of opioid receptor agonist and chemokine receptor antagonist produces a synergistic analgesic effect. 1.3 Microglial cells and astrocytes are the source of the investigated nociceptive factors, therefore they are the target of pharmacological modulation. 2. In a primary culture of microglia and/or astrocytes: Pharmacological modulation of chemokine receptors and intracellular pathways important in nociception will enable us to understand their role and determine their impact on the effects of opioids. RESEARCH METHODOLOGY: Animals: All experiments will be conducted in accordance with the guidelines of the Animal Research Ethics Committee of the Institute of Pharmacology of the Polish Academy of Sciences in Krakow. Model of neuropathic pain (Bennett model): Unilateral loose ligation of the sciatic nerve in rats and/or mice. Administration of studied compounds: Intraperitoneal/subarachnoid administration of substances such as antagonists of chemokine receptors, inhibitors of intracellular pathways, agonist of opioid receptors: tramadol). Behavioral tests: Von Frey and cold plate tests. Biochemical tests: RNA Analysis: qRT-PCR. Protein analysis: Western blot/ELISA/Protein microarrays/Immunohistochemistry. Cell cultures: Primary cultures of microglia and/or astroglia. IMPACT OF THE RESULTS: According to the International Association for the Study of Pain IASP, one in five Europeans suffers from chronic pain. Symptoms which accompany the pain contribute to a significant deterioration of the quality of life. Therefore, development of an effective method of treatment is such an important issue. Defining the role of a number of immunological factors which are released during the development of neuropathy by glial cells will allow us to understand its pathomechanism and expand our knowledge in this field. Suggested research focuses on microglia and astrocytes, which have been recently recognized as important modulators of nociception. The results obtained in the project will complement the knowledge on the effects of analgesic drugs such as minocycline, parthenolide and maraviroc which are used in the clinic, but not in the treatment of neuropathy. Moreover, the use of new substances such as CXCR3 antagonist will contribute to the understanding of mechanisms conditioning the generation and maintenance of neuropathic pain. Combined administrations of analgesic opioids, which are currently used in the clinic, along with substances blocking the activity of glial cells via their receptors or intracellular pathways, can increase the efficiency of these opioids. This may result in enhancing the quality of life of patients suffering from neuropathic pain. Therefore, it seems that the pharmacological modulation of glia is a new and promising therapeutic approach in the treatment of a painful neuropathy.
  • Scientific award of L’Oréal Unesco For Women In Science, Anna Piotrowska-Murzyn, PhD
    Wednesday, 14 November 2018
  • START Scholarship Foundation for Polish Science (FNP), Anna Piotrowska-Murzyn, PhD
    Saturday, 26 May 2018
  • scholarship for outstanding scientific achievements awarded by President of the Polish Academy of Sciences, Anna Piotrowska-Murzyn, PhD
    Wednesday, 13 December 2017