Analgesic Response to Ketamine Linked to Circulating microRNA in Complex Regional Pain Syndrome


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Analgesic Response to Intravenous Ketamine

Is Linked to a Circulating microRNA Signature

in Female Patients

With Complex Regional Pain Syndrome

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The ability to measure Micro RNS’s (miRNA) in blood looks like it may become an important tool someday once it is available for the clinic. It could be used to predict if your condition will respond to various medications.

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MicroRNAs are emerging as important modulators of various psychiatric (schizophrenia, bipolar disorder) and neurological conditions including pain, epilepsy, cognitive dysfunction, neuronal development, structure and function. “MicroRNAs are small, non-coding RNAs that act as post-transcriptional regulators of gene expression.  miRNA’s can be affected by morphine and affected by other drugs. It is hoped that complex clinical phenotypes may be profiled in assays of peripheral blood and may predict response to treatment such as in this study. Ketamine is given for selected patients that have failed to respond to standard treatment.

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This research was published in Pain, June 2015, by Professor Schwartzman’s group at Drexel University. Seven of his patients with Complex Regional Pain Syndrome were ketamine responders and 6 were poor responders. They note that, “Although [ketamine] treatment is generally effective, approximately 30% of patients have an inadequate response to ketamine.”

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“Stability in circulation and dysregulation in disease state are 2 features making extracellular miRNAs useful candidates for biomarker discovery. Alterations in miRNA profiles have been reported for rheumatoid arthritis and systemic lupus erythematosus as well as for painful conditions such as irritable bowel syndrome, chronic bladder syndrome, endometriosis, and migraine. Cerebrospinal fluid from patients with fibromyalgia showed differential expression of 9 miRNAs.”

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Quoting directly from the article:

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Highlights

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•We studied ketamine treatment–induced miRNA alterations in blood from patients with CRPS.
•Differential miRNA expression was observed in whole blood before and after treatment.
•Before therapy, 33 miRNAs differed between responders and poor responders.
•Lower pretreatment levels of miR-548d-5p may contribute to higher UDP-GT activity.
•Circulating miRNAs can be potential biomarkers in predicting treatment response.

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From the Abstract

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Investigation of the mechanistic significance of hsa-miR-548d-5p downregulation in poor responders showed that this miRNA can downregulate UDP-glucuronosyltransferase UGT1A1 mRNA. Poor responders had a higher conjugated/unconjugated bilirubin ratio, indicating increased UGT1A1 activity. We propose that lower pretreatment levels of miR-548d-5p may result in higher UDP-GT activity, leading to higher levels of inactive glucuronide conjugates, thereby minimizing the therapeutic efficacy of ketamine in poor responders.

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Perspective

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This study suggests the usefulness of circulating miRNAs as potential biomarkers. Assessing miRNA signatures before and after treatment demonstrated miRNA alterations from therapy; differences in miRNA signature in responders and poor responders before therapy indicate prognostic value. Mechanistic studies on altered miRNAs can provide new insights on disease.

 

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From the Discussion

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Ketamine is also considered to be the prototype for a new generation of glutamate- based antidepressants that can alleviate depression within hours of treatment. Several biological measures have been explored to characterize treatment response and to gain insight into mechanisms underlying the rapid antidepressant effects of ketamine. A plasma metabolomics study in patients with bipolar depression suggested that the basal mitochondrial b-oxidation of fatty acids differed between responders and nonresponders to ketamine. Other studies have shown differences in baseline plasma concentrations of D-serine, serum levels of interleukin 6, and plasma levels of Shank3, a postsynaptic density protein involved in NMDA receptor tethering and dendritic spine rearrangement.

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Differences in the ability to metabolize ketamine because of interindividual differences and pharmacogenetic factors have been proposed to contribute to the varied responses to ketamine therapy and its clinical outcome. Similar conclusions have been drawn for patients with depression; plasma from patients with treatment- resistant bipolar depression who had undergone a single 40-minute infusion of a subanesthetic dose of ketamine showed that although NK is an initial metabolite, it is not the major circulating metabolite. This again suggests that other downstream metabolites of ketamine may play a role in the pharmacological effects of the drug. It is also known that (2S,6S)-hydroxynorketamine is an active and selective inhibitor of the a7 subtype of the nicotinic acetylcholine receptor; this activity was shown to contribute to the pharmacological responses associated with the antidepressant activity of (R,S)-ketamine. We postulate that in patients with CRPS, 1 factor contributing to resistance is an altered pharmacokinetic profile produced by enhanced elimination of active metabolites downstream of NK, which is mediated by hsa-miR-548d-5p. However, because we have relied on indirect evidence of a higher percentage of direct/indirect bilirubin in poor responders, indicating increased UDP-GT enzyme activity, additional studies investigating hydroxynorketamine and its downstream metabolites along with their glucuronide conjugates in plasma and urine will provide direct evidence for the role of miR-548d-5p in mediating response to ketamine therapy in responders and poor responders.

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They noted a significant difference in body weight between responders and nonresponders (heavier), but not in duration of disease and analgesic response to ketamine. Toward that end, they will publish separately upon

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… investigating the link between miR-34a, which showed 28-fold reduction in poor responders relative to responders (Table 2), and the neuroendocrine system….

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From the Conclusion

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Our studies showed that miR-548d-5p can regulate UDP-GT but not CYP3A4, suggesting that UDP-GT activity in responders and poor responders may be mediated by differences in the level of circulating miR-548d-5p. Lower levels of miR-548d-5p in poor responders before treatment could result in higher UDP-GT activity, leading to the production of more inactive glucuronide conjugates and faster elimination of active ketamine metabolites downstream of NK. Thus, the levels of hsa-miR-548d-5p could minimize the therapeutic efficacy of ketamine and pain relief. Differences in miRNA signature can thus provide molecular insights distinguishing responders from poor responders. High failure rates of drugs targeted to treat neuropathic pain warrant changes in approaches. Studies targeting well-defined patient populations for clinical trials will play a crucial in developing drugs that may be efficacious in a subset of patients. Extending this approach to other treatment and outcome assessments might permit stratification of patients for maximal therapeutic outcome.

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How frustrating it is for patients and family who must cope with an intractable condition such as pain or Bipolar Disorder or treatment resistant Major Depression that has failed all commonly prescribed medications. For all of them, we need changes in approach.

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“High failure rates of drugs targeted

to treat neuropathic pain

warrant changes in approaches.”

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Perhaps scientists reading this would comment upon how it may relate to tolerance as it differentially occurs in those receiving intermittent ketamine vs continuous intravenous infusion.

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Dysregulation of miRNA’s has been shown in psychiatric disorders including depression and schozophrenia, neurodevelopmental disorders, cognitive dysfunction,  epilepsy, chronic pain states with implication for the cause and treatment of these disorders.

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Research targeting miRNA’s as novel treatment for depression has shown that chronic fluoxetine, repeated electroconvulsive shock therapy, and acute ketamine have the capacity to alter hippocampal miRNA levels.

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It is hoped these tests may be available someday clinically as the cost of off-label treatment not covered by insurance is a great burden for those already disabled by intractable pain or treatment resistant depression.

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PUBLIC WARNING

warning reprinted with permission of Demitri Papolos, MD
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Ketamine is a controlled substance.
Administered improperly, or without the guidance of a qualified doctor,
Ketamine may cause injury or death.
No attempt should be made to use Ketamine
in the absence of counsel from a qualified doctor.

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The material on this site is for informational purposes only.
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It is not legal for me to provide medical advice without an examination.

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It is not a substitute for medical advice, diagnosis or treatment provided by a qualified health care provider.

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This site is not for email and not for appointments.

If you wish an appointment, please telephone the office to schedule.

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For My Home Page, click here:  Welcome to my Weblog on Pain Management!

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Please ignore the ads below. They are not from me.

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LDN World Database – Low Dose Naltrexone


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This is a database of persons who have tried low dose naltrexone, their diagnosis, dosage and response to it, if any. The database lists many different medical conditions.

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For example, persons with Multiple Sclerosis, will choose the link above, that has hundreds of persons with MS who have tried naltrexone. Don’t forget to see more pages once you reach the bottom. For a graph of the overall responses, then go back to the main link on Multiple Sclerosis where you see these choices:

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To view the database please click HERE

To view the Graph on how people feel about LDN please click HERE

To add your experience with LDN please click HERE – of course first select the condition you have, so your entry falls into the proper category.

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If your condition is different, just select the condition from the list on left.

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For example for fibromyalgia:

To view the database please click HERE

To view the Graph on how people feel about LDN please click HERE

To add your experience with LDN please click HERE

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Here for Irritable Bowel Syndrome, Crohn’s or Ulcerative Colitis.

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If your condition is not listed, check Other on the left side of the list.

This forum is from LDN Research Trust, a registered non-profit Charity based in the UK, with participants from many countries internationally.

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I will soon be posting several case reports of my patient responders, persons with intractable pain from various conditions. Some have been pain free one or two years on naltrexone. Some who had years of previously intractable pain have responded to low dose naltrexone and remained pain free more than one year after discontinuing LDN.

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MECHANISM

for those who like to know the science

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We have known for decades that naltrexone binds to the mu opioid receptor. It blocks the effect of opioids like morphine at the mu receptor. We now know it also acts at another receptor.

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You may wish to watch this video that explains Toll Like Receptors, TLRs for short. This is a lecture by Dr. Rachel Allen, whose PhD in immunology is from Oxford University. After that, she worked at Cambridge University on innate immune receptors such as the TLR’s.

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In 2008, it was shown that naltrexone binds at one of the Toll Like Receptors, the TLR4 receptor. There are 13 Toll Like Receptors, and so far they have studied naltrexone only at one of them, the TLR4. That is important because the TLR receptors are part of the innate immune system.

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The Toll Like Receptors are not like other receptors. Not these snug little pockets where naltrexone binds. Instead the Toll Like Receptors are like an entire football field, with enormous nooks and crannies where it has many interactions with many molecules. Now, in 2010, scientists are asking if naloxone or naltrexone is acting at TLR4 or even higher up in the cascade.

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The study of immune cell glial interactions is in its infancy. Glial cells are the immune cells in your central nervous system (brain, spinal cord). They are very involved in dysregulation of pain systems, neuroinflammation, and some neurological diseases such as Multiple Sclerosis, Alzheimer’s, Parkinson’s Disease, ALS, infections of the brain, etc.

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One of our distinguished glial scientists, Linda Watkins, PhD, in October 2010, said we are not even sure naltrexone binds to the Toll Like Receptor. Rather, it involves AKT1, close to the TLR4 receptor, very very high up in the cascade at the dimerization step, the recruitment of CD14. This is being worked out now.

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Dr. Watkins with Kennar Rice, PhD, from NIH/NIDA, et al, has a paper in press in Cell:

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Glial activation participates in the mediation of pain including neuropathic pain, due to release of neuroexcitatory, proinflammatory products. Glial activation is now known to occur in response to opioids as well. Opioid-induced glial activation opposes opioid analgesia and enhances opioid tolerance, dependence, reward and respiratory depression. Such effects can occur, not via classical opioid receptors, but rather via non-stereoselective activation of toll-like receptor 4 (TLR4), a recently recognized key glial receptor participating in neuropathic pain as well. This discovery identifies a means for separating the beneficial actions of opioids (opioid receptor mediated) from the unwanted side-effects (TLR4/glial mediated) by pharmacologically targeting TLR4. Such a drug should be a stand-alone therapeutic for treating neuropathic pain as well. Excitingly, with newly-established clinical trials of two glial modulators for treating neuropathic pain and improving the utility of opioids, translation from rats-to-humans now begins with the promise of improved clinical pain control.

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For chronic pain, targets of interest are: glial attenuation, p38 MAPK inhibition.

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Of interest, a commonly prescribed pain medication, amitriptyline, is a TLR4 inhibitor (Hutchinson, 2010).

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You can read many new publications on glia that I posted on my site here, or find it from the banner at top:

Donate to Eliminate Neuropathic Pain

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I am a member of a Neuroinflammation Research Consortium that will be studying these many conditions, some that are painful, others that are not. They involve glia and neuroinflammation.

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For more discussion of mechanisms of action of naltrexone and other publications I have posted, see here, particularly the paper by Zhang, Hong, Kim et al.

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Finally, for those who may feel they are losing heart because medicine has been too slow to adopt the use of low dose naltrexone, let me point this out:

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Dr. Linda Watkins is a University of Colorado Distinguished Professor of Psychology & Neuroscience at the University of Colorado Boulder. She is a world-renown leader in glia research and the neurological applications of glial attenuation, with a focus on alleviation of chronic pain. She is the recipient of the highest award for distinguished basic science research from the American Pain Society and the 2010 John Liebeskind Pain Management Research Award from the American Academy of Pain Management. She has over 300 peer-reviewed publications including articles in Nature, Science, Nature Neuroscience, and Journal of Neuroscience. She received over $2 million in NIH grants supporting 6 generations of IL-10 gene therapy research culminating in XT-101.

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The material on this site is for informational purposes only.

It is not a substitute for medical advice, diagnosis or treatment provided by a qualified health care provider.

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For My Home Page, click here:  Welcome to my Weblog on Pain Management!

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