Cytokine modulation is necessary for efficacious treatment of experimental neuropathic pain

Causal association between circulating inflammatory markers and sciatica development: a Mendelian randomization study

Background

This research explores the causal association between circulating inflammatory markers and the development of sciatica, a common and debilitating condition. While previous studies have indicated that inflammation may be a factor in sciatica, but a thorough genetic investigation to determine a cause-and-effect relationship has not yet been carried out. Gaining insight into these interactions may uncover novel treatment targets.

Methods

We utilized data from the OpenGWAS database, incorporating a large European cohort of 484,598 individuals, including 4,549 sciatica patients. Our study focused on 91 distinct circulating inflammatory markers. Genetic variations were employed as instrumental variables (IVs) for these markers. The analysis was conducted using inverse variance weighting (IVW) as the primary method, supplemented by weighted median-based estimation. Validation of the findings was conducted by sensitivity studies, utilizing the R software for statistical computations.

Results

The analysis revealed that 52 out of the 91 inflammatory markers studied showed a significant causal association with the risk of developing sciatica. Key markers like CCL2, monocyte chemotactic protein-4, and protein S100-A12 demonstrated a positive correlation. In addition, there was no heterogeneity or horizontal pleiotropy in these results. Interestingly, a reverse Mendelian randomization analysis also indicated potential causative effects of sciatica on certain inflammatory markers, notably Fms-related tyrosine kinase 3 ligands.

Discussion

The study provides robust evidence linking specific circulating inflammatory markers with the risk of sciatica, highlighting the role of inflammation in its pathogenesis. These findings could inform future research into targeted treatments and enhance our understanding of the biological mechanisms underlying sciatica.

Deciphering Neuroprotective Effect of Rosmarinus officinalis L. (syn. Salvia rosmarinus Spenn.) through Preclinical and Clinical Studies

Rosmarinus officinalis L. (RO, rosemary) is a well-known medicinal, aromatic, and culinary herb with traditional use in European folk medicine against memory deficits and neurodegenerative disorders. This review highlights the different neuroprotective activities of RO investigated in both preclinical and clinical studies, as well as in silico molecular docking of bioactive compounds found in RO. The neuroprotective effect of RO was searched through databases including PubMed, Web of Science (WoS), Scopus, and Clinical Trials using the keywords "Rosmarinus officinalis, rosemary, neuroprotective effect, memory, cognitive dysfunction, Alzheimer's disease." RO, which is rich in secondary metabolites that have memory-enhancing potential, has displayed neuroprotection through different molecular mechanisms such as inhibition of cholinesterase, modulation of dopaminergic and oxytocinergic systems, mediation of oxidative and inflammatory proteins, involved in neuropathic pain, among others. RO extracts exhibited antidepressant and anxiolytic activities. Also, the plant has shown efficacy in scopolamine-, lipopolysaccharide-, AlCl3-, and H2O2-induced amnesia as well as amyloid-beta- and ibotenic acid-induced neurotoxicity and chronic constriction injury-related oxidative stress memory and cognitive impairments in animal models. A few clinical studies available supported the neuroprotective effects of RO and its constituents. However, more clinical studies are needed to confirm results from preclinical studies further and should include not only placebo-controlled studies but also studies including positive controls using approved drugs. Many studies underlined that constituents of RO may have the potential for developing drug candidates against Alzheimer's disease that possess high bioavailability, low toxicity, and enhanced penetration to CNS, as revealed from the experimental and molecular docking analysis.

The role of walking exercise on axonal regrowth and neuropathic pain markers in dorsal root ganglion after sciatic nerve injury

The aim of this study was to determine whether walking exercise can regulate the expression level of neuropathic pain- and inflammatory response markers in the ipsilateral lumbar 4 to 6 dorsal root ganglion neurons after sciatic nerve injury (SNI). The experimental rats were randomly divided into seven groups: the normal control group, sedentary groups for 3, 7, and, 14 days postinjury (dpi), and walking exercise groups for 3, 7, and 14 dpi. Western blot techniques were used to evaluate specific neuropathic pain- and cytokine markers and mechanical allodynia was confirmed by paw withdrawal test. Mechanical allodynia was significantly improved in the walking exercise group compared to the sedentary group at all 7, 10, and 14 dpi. Furthermore, growth associated protein 43 and brain-derived neurotrophic factor levels were significantly increased in the walking exercise groups compared to the sedentary group at all 3, 7, and 14 dpi. Conversely, nuclear factor kappa-light-chain-enhancer of activated B cells, interleukin-6, tumor necrosis factor α, calcitonin gene-related peptide, and c-Fos expression levels were significantly decreased in the walking exercise groups compared to the sedentary group at all 3, 7, and 14 dpi. These findings suggest meaningful information that aggressive rehabilitation walking exercise applied early after SNI might be improve mechanical allodynia, neuropathic pain and inflammatory response markers following SNI.

Novel Drug Targets and Emerging Pharmacotherapies in Neuropathic Pain

Neuropathic pain is a debilitating condition characterized by abnormal signaling within the nervous system, resulting in persistent and often intense sensations of pain. It can arise from various causes, including traumatic nerve injury, neuropathy, and certain diseases. We present an overview of current and emerging pharmacotherapies for neuropathic pain, focusing on novel drug targets and potential therapeutic agents. Current pharmacotherapies, including tricyclic antidepressants, gabapentinoids, and serotonin norepinephrine re-uptake inhibitors, are discussed, as are emerging treatments, such as ambroxol, cannabidiol, and N-acetyl-L-cysteine. Additionally, the article highlights the need for further research in this field to identify new targets and develop more effective and targeted therapies for neuropathic pain management.

Systemic and Peripheral Mechanisms of Cortical Stimulation-Induced Analgesia and Refractoriness in a Rat Model of Neuropathic Pain

Epidural motor cortex stimulation (MCS) is an effective treatment for refractory neuropathic pain; however, some individuals are unresponsive. In this study, we correlated the effectiveness of MCS and refractoriness with the expression of cytokines, neurotrophins, and nociceptive mediators in the dorsal root ganglion (DRG), sciatic nerve, and plasma of rats with sciatic neuropathy. MCS inhibited hyperalgesia and allodynia in two-thirds of the animals (responsive group), and one-third did not respond (refractory group). Chronic constriction injury (CCI) increased IL-1β in the nerve and DRG, inhibited IL-4, IL-10, and IL-17A in the nerve, decreased β-endorphin, and enhanced substance P in the plasma, compared to the control. Responsive animals showed decreased NGF and increased IL-6 in the nerve, accompanied by restoration of local IL-10 and IL-17A and systemic β-endorphin. Refractory animals showed increased TNF-α and decreased IFNγ in the nerve, along with decreased TNF-α and IL-17A in the DRG, maintaining low levels of systemic β-endorphin. Our findings suggest that the effectiveness of MCS depends on local control of inflammatory and neurotrophic changes, accompanied by recovery of the opioidergic system observed in neuropathic conditions. So, understanding the refractoriness to MCS may guide an improvement in the efficacy of the technique, thus benefiting patients with persistent neuropathic pain.

Natural Herbal Non-Opioid Topical Pain Relievers-Comparison with Traditional Therapy

Pain is the predominant symptom of many clinical diseases and is frequently associated with neurological and musculoskeletal problems. Chronic pain is frequent in the elderly, causing suffering, disability, social isolation, and increased healthcare expenses. Chronic pain medication is often ineffective and has many side effects. Nonsteroidal over-the-counter and prescription drugs are frequently recommended as first-line therapies for pain control; however, long-term safety issues must not be neglected. Herbs and nutritional supplements may be a safer and more effective alternative to nonsteroidal pharmaceuticals for pain management, especially when used long-term. Recently, topical analgesic therapies have gained attention as an innovative approach due to their sufficient efficacy and comparatively fewer systemic side effects and drug-drug interactions. In this paper, we overview the main natural herbal pain relievers, their efficacy and safety, and their potential use as topical agents for pain control. Although herbal-derived medications are not appropriate for providing quick relief for acute pain problems, they could be used as potent alternative remedies in managing chronic persistent pain with minimal side effects.

Insight into the possible mechanism(s) involved in the antinociceptive and antineuropathic activity of Descurainia sophia L. Webb ex Prantl essential oil

ETHNOPHARMACOLOGICAL RELEVANCE

Descurainia sophia (L.)(Brassicaceae), popularly known as "Khaksheer", is a native species widely distributed in Iran. The seeds and essential oil has been used in local traditional medicine (Persian folk ethnomedicine) to treat fever, inflammation, back pain, and headache.

AIM OF THE STUDY

To investigate in vitro anti-nociceptive and antineuropathic activities of Descurainia sophia seeds essential oil (DSEO) in rats and to determine the possible mechanism(s) involved.

MATERIALS AND METHODS

The antinociceptive activity of DSEO or Linolenic acid (LA) was evaluated using the formalin induced paw licking test followed by determination on the role of NO-cGMP-K+ channel pathway as well as a number of non-opioid receptor systems (vanilloid, dopamine, cannabinoid, serotonin, peroxisome proliferator activated, and adrenergic receptors) in the modulation of DSEO-induced antinociceptive activity. Additionally, the cervical spinal cord contusion (CCS) model was used to study antineuropathic potential of DSEO or LA.

RESULTS

DSEO exerted significant (p < 0.05) antinociceptive activity in formalin test (both phases) and altered mechanical allodynia and hyperalgesia observed in the CCS model. Pretreatment with glibenclamide, Nω-nitro-L-arginine methyl ester, tranilast, methylene blue, SCH23390, SR141716A and SR144528 restored DSEO-induced antinociceptive activity observed in the formalin test. Furthermore, LA also reduced nociceptive responses induced in the formalin and CCS models.

CONCLUSION

DSEO inhibits inflammatory mediated nociceptive response partly via the modulation of NO-cGMP-K+ channels pathway well as the activation of vanilloid, dopamine, and cannabinoid receptors, and exerts antineuropathic activity possibly via the modulation of inflammatory mediated activity. Thus, these findings confirm the Persian ethno-medicine claim on the efficacy of D. Sophia.

Potential association factors for developing effective peptide-based cancer vaccines

Peptide-based cancer vaccines have been shown to boost immune systems to kill tumor cells in cancer patients. However, designing an effective T cell epitope peptide-based cancer vaccine still remains a challenge and is a major hurdle for the application of cancer vaccines. In this study, we constructed for the first time a library of peptide-based cancer vaccines and their clinical attributes, named CancerVaccine (https://peptidecancervaccine.weebly.com/). To investigate the association factors that influence the effectiveness of cancer vaccines, these peptide-based cancer vaccines were classified into high (HCR) and low (LCR) clinical responses based on their clinical efficacy. Our study highlights that modified peptides derived from artificially modified proteins are suitable as cancer vaccines, especially for melanoma. It may be possible to advance cancer vaccines by screening for HLA class II affinity peptides may be an effective therapeutic strategy. In addition, the treatment regimen has the potential to influence the clinical response of a cancer vaccine, and Montanide ISA-51 might be an effective adjuvant. Finally, we constructed a high sensitivity and specificity machine learning model to assist in designing peptide-based cancer vaccines capable of providing high clinical responses. Together, our findings illustrate that a high clinical response following peptide-based cancer vaccination is correlated with the right type of peptide, the appropriate adjuvant, and a matched HLA allele, as well as an appropriate treatment regimen. This study would allow for enhanced development of cancer vaccines.

Integrating the Gut Microbiome and Stress-Diathesis to Explore Post-Trauma Recovery: An Updated Model

Musculoskeletal conditions of traumatic and non-traumatic origin represent an ongoing health challenge. While the last three decades have seen significant advancement in our understanding of musculoskeletal conditions, the mechanisms of a delayed or lack of recovery are still a mystery. Here, we present an expansion of the integrated stress-diathesis model through the inclusion of the gut microbiome. Connecting the microbiome with known adverse neurobiologic, microbiologic and pathophysiologic sequelae following an injury, trauma or stressful event may help improve our knowledge of the pathogenesis of poor recovery. Such knowledge could provide a foundation for the exploration and development of more effective interventions to prevent the transition from acute to chronic pain.

High-mobility group box 1-mediated hippocampal microglial activation induces cognitive impairment in mice with neuropathic pain

Clinical evidence indicates that cognitive impairment is a common comorbidity of chronic pain, including neuropathic pain, but the mechanism underlying cognitive impairment remains unclear. Neuroinflammation plays a critical role in the development of both neuropathic pain and cognitive impairment. High-mobility group box 1 (HMGB1) is a proinflammatory molecule and could be involved in neuroinflammation-mediated cognitive impairment in the neuropathic pain state. Hippocampal microglial activation in mice has been associated with cognitive impairment. Thus, the current study examined a potential role of HMGB1 and microglial activation in cognitive impairment in mice with neuropathic pain due to a partial sciatic nerve ligation (PSNL). Mice developed cognitive impairment over two weeks, but not one week, after nerve injury. Nerve-injured mice demonstrated decreased nuclear fraction HMGB1, suggesting increased extracellular release of HMGB1. Furthermore, two weeks after PSNL, significant microglia activation was observed in hippocampus. Inhibition of microglial activation with minocycline, local hippocampal microglia depletion with clodronate liposome, or blockade of HMGB1 with either glycyrrhizic acid (GZA) or anti-HMGB1 antibody in PSNL mice reduced hippocampal microglia activation and ameliorated cognitive impairment. Other changes in the hippocampus of PSNL mice potentially related to cognitive impairment, including decreased hippocampal neuron dendrite length and spine densities and decreased α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor (AMPAR) subunits, were prevented with anti-HMGB1 antibody treatment. The current findings suggest that neuro-inflammation involves a number of cellular-level changes and microglial activation. Blocking neuro-inflammation, particularly through blocking HMGB1 could be a novel approach to reducing co-morbidities such as cognitive impairment associated with neuropathic pain.

Miconazole Mitigates Acetic Acid-Induced Experimental Colitis in Rats: Insight into Inflammation, Oxidative Stress and Keap1/Nrf-2 Signaling Crosstalk

Ulcerative colitis (UC) is the most common type of inflammatory bowel disease, characterized by oxidative stress and elevated pro-inflammatory cytokines. Miconazole is an azole antifungal that stimulates the expression of antioxidant enzymes via Nrf2 activation, which consequently inhibits ROS formation and NF-κB activation. Hence, the present study aimed to investigate the protective effect of miconazole, sulfasalazine (as a reference drug) and their combination on acetic acid (AA)-induced UC in a rat model which was induced by intra-rectal administration of 4% AA. Rats were pretreated with miconazole (20 and 40 mg/kg, orally) or sulfasalazine (100 mg/kg, orally), or their combination (20 mg/kg miconazole and 50 mg/Kg of sulfasalazine, orally). Pretreatment with miconazole significantly reduced wet colon weight and macroscopic scores, accompanied by a significant amelioration of the colonic architecture disorder. Moreover, the treatment also significantly decreased the malondialdehyde (MDA) level and prevented the depletion of superoxide dismutase (SOD) activity and GSH content in inflamed colons. Additionally, the treatment showed suppressive activities on pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and C-reactive protein (CRP), and upregulated the anti-inflammatory cytokine interleukin-10 (IL-10). Moreover, the treatment upregulated the protein levels of Nrf-2 and heme oxygenase-1 (HO-1) in the colon tissue. Taken together, miconazole is effective in alleviating AA-induced colitis in rats, and the mechanism of its action is associated with the activation of Nrf2-regulated cytoprotective protein expression.

Component-target network and mechanism of Qufeng Zhitong capsule in the treatment of neuropathic pain

ETHNOPHARMACOLOGICAL RELEVANCE

Qufeng Zhitong capsule (QFZTC) is a traditional Chinese medicine (TCM) clinically used for treating pain. However, the active ingredients of QFZTC and its pharmacological mechanism in the treatment of neuropathic pain (NP) remain unclear.

AIM OF THE STUDY

We aimed to identify the active ingredients of QFZTC and reveal its target genes and underlying mechanism of action in NP.

MATERIALS AND METHODS

High-performance liquid chromatography (HPLC) was used to identify the active ingredients of QFZTC. Network pharmacology analysis was conducted to determine the core targets and pathway enrichment of QFZTC. An NP mice model was established through chronic compression injury (CCI) surgery of the sciatic nerve, while von Frey instrumentation and a thermal stimulator were employed to measure the sensitivity of mice to mechanical and thermal stimuli. Immunofluorescence was used to observe the expression of TLR4 and p-P65 in microglia. Western blotting was used to detect the levels of protein expression of Iba-1, TLR4, MyD88, P65, p-P65, and c-Fos, while ELISA kits were used to detect the release of TNF-α, IL-6, and IL-1β.

RESULTS

Seven active ingredients were identified in QFZTC: gallic acid, loganylic acid, syringin, corilagin, loganin, ellagic acid, and osthole. Network analysis identified TLR4, TNF, IL6, IL1β, and c-Fos as core targets, and Toll-like receptors and NF-κB as core signaling pathways. Treatment with QFZTC significantly relieved mechanical allodynia and thermal hyperalgesia in CCI mice models. CCI induced an increase in the expression of TLR4 and p-P65 in microglia, whereas QFZTC dose-dependently reduced the expression of Iba-1, TLR4, MyD88, and p-P65 in the spinal cord. QFZTC inhibited the expression of the c-Fos pain marker and reduced the expression of the TNF-α, IL-6, and IL-1β inflammatory factors.

CONCLUSION

We combined the active ingredients of QFZTC with network pharmacology research to clarify its biological mechanism in the treatment of NP. We demonstrated that QFZTC reduced NP in mice probably through regulating the spinal microglia via the TLR4/MyD88/NF-κB signaling pathway. Hence, QFZTC could be regarded as a potential drug for relieving NP.

Frailty and pain, human studies and animal models

The hypothesis that pain can predispose to frailty development has been recently investigated in several clinical studies suggesting that frailty and pain may share some mechanisms. Both pain and frailty represent important clinical and social problems and both lack a successful treatment. This circumstance is mainly due to the absence of in-depth knowledge of their pathological mechanisms. Evidence of shared pathways between frailty and pain are preliminary. Indeed, many clinical studies are observational and the impact of pain treatment, and relative pain-relief, on frailty onset and progression has never been investigated. Furthermore, preclinical research on this topic has yet to be performed. Specific researches on the pain-frailty relation are needed. In this narrative review, we will attempt to point out the most relevant findings present in both clinical and preclinical literature on the topic, with particular attention to genetics, epigenetics and inflammation, in order to underline the existing gaps and the potential future interventional strategies. The use of pain and frailty animal models discussed in this review might contribute to research in this area.

The protective effects of hesperidin against paclitaxel-induced peripheral neuropathy in rats

Paclitaxel (PTX), which is widely used in the treatment of solid tumors, leads to dose limitation because it causes peripheral neuropathy. This study was conducted to evaluate the potential effects of hesperidin (HES), which has various biological and pharmacological properties, against PTX-induced sciatic nerve damage. For this purpose, Sprague Dawley rats were given PTX 2 mg/kg/b.w for 5 days, then 100 or 200 mg/kg/b.w HES for 10 days, and behavioral tests were conducted at the end of the experiment. The data obtained show that PTX-induced MDA, NF-κB, IL-1β, TNF-α, COX-2, nNOS, JAK2, STAT3, and GFAP levels decreased with HES administration. Moreover, it was observed that SOD, CAT, and GPx activities inhibited by PTX increased with HES administration. It was determined that PTX caused apoptosis in the sciatic nerve by increasing Caspase-3 and Bax levels and suppressing Bcl-2 levels. HES, on the other hand, showed an anti-apoptotic effect, increasing Bcl-2 levels and decreasing Caspase-3 and Bax levels. Also, it was observed that PTX could cause endoplasmic reticulum stress (ERS) by increasing PERK, IRE1, ATF-6, GRP78 and CHOP mRNA transcript levels, while HES could alleviate ERS by suppressing them. The results indicate that neuropathic pain associated with PTX-induced peripheral neuropathy can be alleviated by HES administration and that it is a promising compound for cancer patients. In addition, it is thought that the results of the present study contain information that will shed light for researchers regarding further studies to be conducted with HES.

Quercetin reduces inflammation in a rat model of diabetic peripheral neuropathy by regulating the TLR4/MyD88/NF-κB signalling pathway

Neuroinflammation contributes significantly to the pathogenesis of diabetic peripheral neuropathy (DPN). Quercetin reportedly exerts neuroprotective effects in DPN. Here, we aimed to evaluate the potential anti-inflammatory effects of quercetin in a DPN rat model. Eight weeks after streptozotocin administration, diabetic rats were treated with quercetin (30 and 60 mg/kg/day orally) for 6 weeks. We assessed the mechanical withdrawal threshold (MWT), nerve conduction velocity (NCV) and morphological changes in sciatic nerves. Additionally, we measured the levels of tumour necrosis factor-alpha (TNF-α), interleukin (IL)-1β, and IL-6 by ELISA and the expression of TLR4, MyD88, and NF-κB in sciatic nerves by western blotting and immunohistochemical assays. Our results revealed that blood glucose levels and body weight were unaltered following quercetin treatment. However, quercetin improved MWT (p < 0.05), NCV (p < 0.05), and pathological changes in the sciatic nerves of DPN rats. Quercetin significantly alleviated the increased expression of TNF-α (p < 0.05) and IL-1β (p < 0.001). Furthermore, high-dose quercetin administration significantly downregulated the expression of TLR4 (p < 0.001), MyD88 (p < 0.001), and NF-κB (p < 0.001) in sciatic nerves of DPN rats. Our findings revealed that quercetin could reduce the levels of inflammatory factors in DPN rats, possibly mediated via the downregulation of the TLR4/MyD88/NF-κB signalling pathway. Collectively, these results suggest that although quercetin did not decreased blood glucose levels or reversed the reduced body weight, it showed anti-inflammatory and neuroprotective effects, which was beneficial for the treatment of DPN.

An Exploration of Blood Marker×Environment Interaction Effects on Pain Severity and Interference Scores in People With Acute Musculoskeletal Trauma

OBJECTIVES

Explore the moderating effects of psychological or social variables on associations between biomarkers of inflammation/stress and clinical reports of pain.

METHODS

This is a cross-sectional exploratory study. Data were drawn from the Systematic Merging of Biology, Mental Health and Environment (SYMBIOME) longitudinal study (clinicaltrials.gov ID no. NCT02711085). Eligible participants were adults who presented to an Urgent Care Centre in Ontario, Canada within 3 weeks of a noncatastrophic musculoskeletal trauma (no surgery or hospitalization). A questionnaire package was given that included the Brief Pain Inventory (capturing pain severity and pain interference) and relevant person-level variables. Blood samples were also drawn for serum analysis of 8 target biomarkers (brain-derived neurotrophic factor, transforming growth factor beta 1 [TGF-β1], c-reactive protein, tumor necrosis factor-α, interleukin [IL]-1β, IL-6, IL-10, and cortisol).

RESULTS

Employment before trauma (employed for pay/not employed for pay) fully moderated the association between tumor necrosis factor-α and pain severity (∆R2=4.4%). Pre-existing psychopathology (yes/no) fully moderated the association between TGF-β1 and pain severity (∆R2=8.0%). Sex (male/female) fully moderated the association between c-reactive protein and pain severity (∆R2=6.3%). A pre-existing pain condition (yes/no) was significantly associated with worse pain interference (R2=7.2%), and partially moderated the effect of IL-1β on pain interference (∆R2=6.9%). Higher peritraumatic life stress significantly explained 8.9% of variance in pain interference alone, and partially moderated the effect of TGF-β1 on interference (∆R2=4.4%).

DISCUSSION

Simple bivariate associations between blood-based markers and clinical symptoms are unlikely to reveal meaningful relationships. However, when stratified by existing person-level or "metadata" variables, an association may exist for at least 1 clinically relevant subgroup.

Celastrol attenuates chronic constrictive injury-induced neuropathic pain and inhibits the TLR4/NF-κB signaling pathway in the spinal cord

Tripterygium wilfordii Hook F. is a well-known but poisonous traditional Chinese medicine used for treating a wide variety of inflammatory and autoimmune disorders. Celastrol, a quinone methyl triterpenoid compound and a representative component of T. wilfordii Hook F., shows a variety of pharmacological activities, such as anti-inflammatory and antitumor activities. Here, we investigated the antineuropathic pain (NP) effect of celastrol and its potential mechanisms. Rats with chronic constrictive injury (CCI)-induced NP were used to evaluate the analgesic effect of celastrol. Gabapentin was used as a reference compound (positive control). The results showed that gabapentin (100 mg/kg, i.p.) and multiple doses of celastrol (0.5, 1 and 2 mg/kg, i.p.) increased the threshold of mechanical and thermal pain in the rats with NP. Western blot results showed that celastrol significantly inhibited the activation of microglia and astrocytes in the spinal cord of rats with NP. Additionally, the levels of the proinflammatory cytokines tumor necrosis factor α (TNF-α), interleukin 1β and interleukin 6, detected by ELISA in the spinal cord of the rats with NP, were significantly inhibited by celastrol. Furthermore, celastrol treatment dramatically inhibited the expression of the TLR4/NF-κB signaling pathway in the spinal cord. Taken together, our findings suggested that celastrol could attenuate mechanical and thermal pain in CCI-induced NP, and this protection might be attributed to inhibiting the TLR4/NF-κB signaling pathway and exerting anti-inflammatory effects in the spinal cord.

Correlation between Hyperalgesia and Upregulation of TNF-α and IL-1β in Aqueous Humor and Blood in Second Eye Phacoemulsification: Clinical and Experimental Investigation

The aim of this study was to explore the correlation between intraoperative hyperalgesia of the second eye and the dynamic changes of tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels in aqueous humor (AH) of the second eye and whole blood after the first eye cataract surgery. A rabbit model of monocular phacoemulsification was established by administration of 0.3% levofloxacin. Whole blood and AH samples from non-surgical eyes in the experimental group (n =25) and second eye in the blank control group (n =15) were obtained and corneal sensitivity was examined after surgery (1, 3, 7, 14, and 21 days postoperatively). TNF-α and IL-1β levels in AH and TNF-α mRNA and IL-1β mRNA levels in whole blood were measured. In a clinical study, 30 patients who underwent bilateral phacoemulsification within 1 month were divided into six groups in accordance with the operation intervals (1, 3, 7, 10, 14, and 21days). TNF-α and IL-1β levels in AH were measured at the beginning of surgery and intraoperative pain was assessed immediately after surgery. Corneal sensitivity (F =244.910, P <0.05), TNF-α and IL-1β levels in AH (F =184.200, 82.900, P <0.05) of non-surgical eyes and in whole blood (F =272.800, 193.530, P <0.05) in the experimental group were significantly higher than the baseline levels after phacoemulsification. In the clinical study, NRS scores of second eye surgery were higher than those of the first eye(P =0.0025) and 19 (63.3%) patients reported more pain during the second eye surgery. TNF-α and IL-1β concentrations in AH of the second eye were significantly higher than those of the first eye (F =123.60, P <0.05; F =59.60, P <0.05). In conclusion, within 1 month after the first eye phacoemulsification, higher pain sensitivity (hyperalgesia) exists in the second eye, which may be related to dynamic changes in TNF-α, IL-1β levels in AH or whole blood.

Platelet-rich plasma and cytokines in neuropathic pain: A narrative review and a clinical perspective

BACKGROUND AND OBJECTIVE

Neuropathic pain arises as a direct consequence of a lesion or disease affecting the somatosensory system. A number of preclinical studies have provided evidence for the involvement of cytokines, predominantly secreted by a variety of immune cells and by glial cells from the nervous system, in neuropathic pain conditions. Clinical trials and the use of anti-cytokine drugs in different neuropathic aetiologies support the relevance of cytokines as treatment targets. However, the use of such drugs, in particularly biotherapies, can provoke notable adverse effects. Moreover, it is challenging to select one given cytokine as a target, among the various neuropathic pain conditions. It could thus be of interest to target other proteins, such as growth factors, in order to act more widely on the neuroinflammation network. Thus, platelet-rich plasma (PRP), an autologous blood concentrate, is known to contain a natural concentration of growth factors and immune system messengers and is widely used in the clinical setting for tissue regeneration and repair.

DATABASE AND DATA TREATMENT

In the present review, we critically assess the current knowledge on cytokines in neuropathic pain by taking into consideration both human studies and animal models.

RESULTS

This analysis of the literature highlights the pathophysiological importance of cytokines. We particularly highlight the concept of time- and tissue-dependent cytokine activation during neuropathic pain conditions.

RESULTS

Conclusion: Thus, direct or indirect cytokines modulation with biotherapies or growth factors appears relevant. In addition, we discuss the therapeutic potential of localized injection of PRP as neuropathic pain treatment by pointing out the possible link between cytokines and the action of PRP.

SIGNIFICANCE

Preclinical and clinical studies highlight the idea of a cytokine imbalance in the development and maintenance of neuropathic pain. Clinical trials with anticytokine drugs are encouraging but are limited by a 'cytokine candidate approach' and adverse effect of biotherapies. PRP, containing various growth factors, is a new therapeutic used in regenerative medicine. Growth factors can be also considered as modulators of cytokine balance. Here, we emphasize a potential therapeutic effect of PRP on cytokine imbalance in neuropathic pain. We also underline the clinical interest of the use of PRP, not only for its therapeutic effect but also for its safety of use.

ERS clinical practice guidelines on treatment of sarcoidosis

BACKGROUND

The major reasons to treat sarcoidosis are to lower the morbidity and mortality risk or to improve quality of life (QoL). The indication for treatment varies depending on which manifestation is the cause of symptoms: lungs, heart, brain, skin, or other manifestations. While glucocorticoids (GC) remain the first choice for initial treatment of symptomatic disease, prolonged use is associated with significant toxicity. GC-sparing alternatives are available. The presented treatment guideline aims to provide guidance to physicians treating the very heterogenous sarcoidosis manifestations.

MATERIALS AND METHODS

A European Respiratory Society Task Force (TF) committee composed of clinicians, methodologists, and patients with experience in sarcoidosis developed recommendations based on the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) methodology. The committee developed eight PICO (Patients, Intervention, Comparison, Outcomes) questions and these were used to make specific evidence-based recommendations.

RESULTS

The TF committee delivered twelve recommendations for seven PICOs. These included treatment of pulmonary, cutaneous, cardiac, and neurologic disease as well as fatigue. One PICO question regarding small fiber neuropathy had insufficient evidence to support a recommendation. In addition to the recommendations, the committee provided information on how they use alternative treatments, when there was insufficient evidence to support a recommendation.

CONCLUSIONS

There are many treatments available to treat sarcoidosis. Given the diverse nature of the disease, treatment decisions require an assessment of organ involvement, risk for significant morbidity, and impact on QoL of the disease and treatment.

MESSAGE

An evidence based guideline for treatment of sarcoidosis is presented. The panel used the GRADE approach and specific recommendations are made. A major factor in treating patients is the risk of loss of organ function or impairment of quality of life.

Sexually Dimorphic Immune and Neuroimmune Changes Following Peripheral Nerve Injury in Mice: Novel Insights for Gender Medicine

Neuropathic pain (NeP) in humans is often a life-long condition with no effective therapy available. The higher incidence of female gender in NeP onset is worldwide reported, and although the cause is generally attributed to sex hormones, the actual mechanisms and the players involved are still unclear. Glial and immune cells take part in NeP development, and orchestrate the neuroimmune and inflammatory response, releasing pro-inflammatory factors with chemoattractant properties that activate resident immune cells and recruit immune cells from circulation. The neuro-immune crosstalk is a key contributor to pain hypersensitivity following peripheral nervous system injury. Our previous works showed that in spite of the fact that female mice had an earlier analgesic response than males following nerve lesion, the recovery from NeP was never complete, suggesting that this difference could occur in the very early stages after injury. To further investigate gender differences in immune and neuroimmune responses to NeP, we studied the main immune cells and mediators elicited both in plasma and sciatic nerves by peripheral nerve lesion. After injury, we found a different pattern of distribution of immune cell populations showing either a higher infiltration of T cells in nerves from females or a higher infiltration of macrophages in nerves from males. Moreover, in comparison to male mice, the levels of cytokines and chemokines were differently up- and down-regulated in blood and nerve lysates from female mice. Our study provides some novel insights for the understanding of gender-associated differences in the generation and perseveration of NeP as well as for the isolation of specific neurodegenerative mechanisms underlying NeP. The identification of gender-associated inflammatory profiles in neuropathy is of key importance for the development of differential biomarkers and gender-specific personalized medicine.

Pain in Women: A Perspective Review on a Relevant Clinical Issue that Deserves Prioritization

Introduction

Gender equity and gender medicine are opportunities not to be missed, and this Expert Group Opinion Paper on pain in women aims to review the treatment of pain conditions mainly affecting women, as well as the fundamental aspects of the different clinical response to drug treatment between the genders, and what can be done for gender-specific rehabilitation.

Methods

Perspective review.

Results

Genotypic and phenotypic differences in pain between the sexes are conditioned by anatomical, physiological, neural, hormonal, psychological, social, and cultural factors, such as the response to pharmacological treatment to control pain. The examination of these factors shows that women are affected by pain diseases more frequently and severely than men and that they report pain more frequently and with a lower pain threshold than men. Some forms of pain are inherently related to gender differences, such as pain related to the genitourinary system. However, other forms of chronic pain are seen more frequently in women than men, such as migraine, rheumatological, and musculoskeletal pain, in particular fibromyalgia.

Discussion

Research is needed into the pathophysiological basis for gender differences in the generation of acute pain and maintenance of chronic pain, including the factors that put women at higher risk for developing chronic pain. In addition, different specialties need to collaborate to develop gender-related diagnostic and therapeutic guidelines, and healthcare professionals need to upskill themselves in the appropriate management of pain using existing diagnostic tools and therapeutic options.

Palmitoylethanolamide and hemp oil extract exert synergistic anti-nociceptive effects in mouse models of acute and chronic pain

The use of products derived from hemp - i.e., cannabis varieties with low Δ⁹-tetrahydrocannabinol (Δ⁹-THC) content - as self-medication for pain and other health conditions is gaining in popularity but preclinical and clinical evidence for their effectiveness remains very limited. In the present study, we assessed the efficacy of a full-spectrum hemp oil extract (HOE; 10, 50 and 100 mg-kg^-1; oral route), alone or in combination with the anti-inflammatory and analgesic agent palmitoylethanolamide (PEA; 10, 30, 100 and 300 mg-kg^-1; oral route), in the formalin and chronic constriction injury (CCI) tests. We found that HOE exerts modest antinociceptive effects when administered alone, whereas the combination of sub-effective oral doses of HOE and PEA produces a substantial greater-than-additive alleviation of pain-related behaviors. Transcription of interleukin (IL)-6 and IL-10 increased significantly in lumbar spinal cord tissue on day 7 after CCI surgery, an effect that was attenuated to the same extent by HOE alone or by the HOE/PEA combination. Pharmacokinetic experiments show that co-administration of HOE enhances and prolongs systemic exposure to PEA. Collectively, our studies lend support to possible beneficial effects of using HOE in combination with PEA to treat acute and chronic pain.

Latent profile analysis of blood marker phenotypes and their relationships with clinical pain and interference reports in people with acute musculoskeletal trauma

Background: The prevalence of inadequate treatments for chronic pain has necessitated the search for biological factors that influence the transition to chronicity.

Methods: Antecubital blood was drawn from those who experienced acute, noncatastrophic musculoskeletal trauma. Follow-up occurred at 1, 3, 6, and 12 months with the primary outcome being Brief Pain Inventory (BPI) Functional Interference scores. Eight markers were chosen for latent profile analysis: brain-derived neurotrophic factor (BDNF); transforming growth factor-beta 1 (TGF-β1); C-reactive protein (CRP); tumor necrosis factor-alpha (TNF-α); interleukins (ILs) 1-beta, 6, and 10; and the stress hormone cortisol.

Results: Mean age of the 106 participants was 44.6 years and 58.5% were female. The final model indicated a three-class solution that could be adequately described by three of the eight markers: class 1 = low concentration of all markers (33.9% of the sample), class 2 = average concentration of all markers (47.7%), and class 3 = high concentration of BDNF and TGF-β1 (18.3%). BPI Pain Interference scores captured at both inception and 6-month follow-up were compared across the three groups. Mean scores were significantly higher in class 3 for the BPI Interference subscale at inception (27.0 [SD 16.4] vs. 35.8 [SD 17.3], P = 0.05) and at 6-month follow-up (2.2 [SD 4.8] vs. 7.3 [SD 10.7], P = 0.03) compared to those of the other two classes.

Conclusions: Although recovered populations are not significantly different in BDNF and TGF-β1 levels, those who experience persisting disability are more likely to have moderate to high levels in serum.

Evaluation of Murine Macrophage Cytokine Production After In Vivo Morphine Treatment

The discovery of opioid receptor expression on immune cells has originated a large research activity on the possible modulation by opioid drugs of immune system responses. In this chapter we describe an easy methodology useful to obtain information about the potential immunomodulatory activity of opioid drugs. An in vivo treatment schedule is used, and macrophages are studied for their ability to release different cytokines.

Pulsed Ultrasound Remedies Post-thoracotomy Hypersensitivity and Increases Spinal Anti-inflammatory Cytokine in Rats

The purpose of the experiment was to study the effect of pulsed ultrasound (PUS) on post-thoracotomy pain and local tissue temperature and to correlate the findings with the alteration in spinal anti-inflammatory and pro-inflammatory cytokines. Mechanical sensitivity, subcutaneous temperature and spinal interleukin-10 (IL-10), IL-6 or tumor necrosis factor-alpha (TNF-α) expression were examined in a rat model of experimental post-thoracotomy pain. Group 1 received a sham surgery where thoracotomy was performed except for rib retraction. Group 2 underwent thoracotomy with rib retraction (TRR). Group 3 received the TRR procedure followed by PUS. Group 4 underwent the TRR procedure followed by only the massage with the ultrasound turned off. Compared with group 1 (sham), groups 2-4 showed a decrease in mechanical withdrawal thresholds on postoperative days (PODs) 10 and 11. On PODs 16, 23 and 30, group 3 (TRR+PUS-1) displayed an increase in mechanical withdrawal thresholds compared with groups 2 and 4. Subcutaneous and body temperatures in group 3 were not prominently different from group 1, group 2 (TRR only) or group 4 (TRR+PUS-0). Compared with group 2, group 3 had an increase in spinal IL-10 level on POD 30 and a decrease in spinal IL-6 or TNF-α expression on PODs 16 and 30. We concluded that mechanical hypersensitivity after TRR is postponed by PUS, and its effect continues for 3 wk. A PUS dose not increase local tissue temperature. The beneficial effect of PUS appears related to upregulation of spinal anti-inflammatory cytokine and downregulation of spinal pro-inflammatory cytokines.

Effects of rosmarinic acid on nervous system disorders: an updated review

Nowadays, the worldwide interest is growing to use medicinal plants and their active constituents to develop new potent medicines with fewer side effects. Precise dietary compounds have prospective beneficial applications for various neurodegenerative ailments. Rosmarinic acid is a polyphenol and is detectable most primarily in many Lamiaceae families, for instance, Rosmarinus officinalis also called rosemary. This review prepared a broad and updated literature review on rosmarinic acid elucidating its biological activities on some nervous system disorders. Rosmarinic acid has significant antinociceptive, neuroprotective, and neuroregenerative effects. In this regard, we classified and discussed our findings in different nervous system disorders including Alzheimer's disease, epilepsy, depression, Huntington's disease, familial amyotrophic lateral sclerosis, Parkinson's disease, cerebral ischemia/reperfusion injury, spinal cord injury, stress, anxiety, and pain.

Therapeutic effects of rosemary (Rosmarinus officinalis L.) and its active constituents on nervous system disorders

Rosemary (Rosmarinus officinalis L.) is an evergreen bushy shrub which grows along the Mediterranean Sea, and sub-Himalayan areas. In folk medicine, it has been used as an antispasmodic, mild analgesic, to cure intercostal neuralgia, headaches, migraine, insomnia emotional upset, and depression. Different investigations have highlighted rosemary neuropharmacological properties as their main topics. Rosemary has significant antimicrobial, anti-inflammatory, anti-oxidant, anti-apoptotic, anti-tumorigenic, antinociceptive, and neuroprotective properties. Furthermore, it shows important clinical effects on mood, learning, memory, pain, anxiety, and sleep. The aim of the current work is to review the potential neuropharmacological effects of different rosemary extracts and its active constituents on nervous system disorders, their relevant mechanisms and its preclinical application to recall the therapeutic potential of this herb and more directions of future research projects. The data were gathered by searching the English articles in PubMed, Scopus, Google Scholar, and Web of Science. The keywords used as search terms were 'Rosmarinus officinalis', 'rosemary', 'nervous system', 'depression', 'memory', 'Alzheimer's disease' 'epilepsy', 'addiction', 'neuropathic pain', and 'disorders'. All kinds of related articles, abstracts and books were included. No time limitation was considered. Both in vitro and in vivo studies were subjected to this investigation. This review authenticates that rosemary has appeared as a worthy source for curing inflammation, analgesic, anti-anxiety, and memory boosting. It also arranges new perception for further investigations on isolated constituents, especially carnosic acid, rosmarinic acid, and essential oil to find exquisite therapeutics and support drug discovery with fewer side effects to help people suffering from nervous system disorders.

Red nucleus IL-6 mediates the maintenance of neuropathic pain by inducing the productions of TNF-α and IL-1β through the JAK2/STAT3 and ERK signaling pathways

We previously reported that interleukin (IL)-6 in the red nucleus (RN) is involved in the maintenance of neuropathic pain induced by spared nerve injury (SNI), and exerts a facilitatory effect via Janus-activated kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) and extracellular signal-regulated kinase (ERK) signal transduction pathways. The present study aimed at investigating the roles of tumor necrosis factor-α (TNF-α) and IL-1β in RN IL-6-mediated maintenance of neuropathic pain and related signal transduction pathways. Being similar to the elevation of RN IL-6 three weeks after SNI, increased protein levels of both TNF-α and IL-1β were also observed in the contralateral RN three weeks after the nerve injury. The upregulations of TNF-α and IL-1β were closely correlative with IL-6 and suppressed by intrarubral injection of a neutralizing antibody against IL-6. Administration of either the JAK2 antagonist AG490 or the ERK antagonist PD98059 to the RN of rats with SNI remarkably increased the paw withdrawal threshold (PWT) and inhibited the up-regulations of local TNF-α and IL-1β. Further experiments indicated that intrarubral injection of exogenous IL-6 in naive rats apparently lowered the PWT of the contralateral hindpaw and boosted the local expressions of TNF-α and IL-1β. Pretreatment with AG490 could block IL-6-induced tactile hypersensitivity and suppress the up-regulations of both TNF-α and IL-1β. However, injection of PD98059 in advance only inhibited the upregulation of IL-1β, but not TNF-α. These findings indicate that RN IL-6 mediates the maintenance of neuropathic pain by inducing the productions of TNF-α and IL-1β. IL-6 induces the expression of TNF-α through the JAK2/STAT3 pathway, and the production of IL-1β through the JAK2/STAT3 and ERK pathways.

Antinociceptive and Anti-Inflammatory Effects of Nypa fruticans Wurmb by Suppressing TRPV1 in the Sciatic Neuropathies

Neuropathic pain is generally characterized by sensory abnormalities such as sensory disorders, hyperalgesia, and allodynia. Recent studies have reported that TRPV1 activation is essential for establishing of inflammation in the neuropathy pain models, showing that the expression of this receptor is increased, and contributing to enhanced thermal sensitivity. Nypa fruticans Wurmb (NF), which was used as a folk remedy, is a plant that is gaining attention due to its various effects. In this study, we investigated the antinociceptive and anti-inflammatory effects of NFE (Nypa fruticans Wurmb extracts) by controlling the neurological function of TRPV1. In sciatic crush injury rat models, a significant level of antinociceptive effect was observed in the thermal hyperalgesia test in which NF extracts (NFE 500 mg/kg) were orally administered, daily. Protein quantification of the sciatic nerve and the of the L4-L6 spinal cord showed a decrease of the TRPV1 expression, the inflammatory expression factor, COX2, and proinflammatory factors in the NFE treated groups. Our results indicate that NFE affects antinociceptive and anti-inflammatory by controlling TRPV1 in sciatic neuropathic pain models.

Gabexate mesilate ameliorates the neuropathic pain in a rat model by inhibition of proinflammatory cytokines and nitric oxide pathway via suppression of nuclear factor-κB

BACKGROUND

This study examined the effects of gabexate mesilate on spinal nerve ligation (SNL)-induced neuropathic pain. To confirm the involvement of gabexate mesilate on neuroinflammation, we focused on the activation of nuclear factor-κB (NF-κB) and consequent the expression of proinflammatory cytokines and inducible nitric oxide synthase (iNOS).

METHODS

Male Sprague-Dawley rats were used for the study. After randomization into three groups: the sham-operation group, vehicle-treated group (administered normal saline as a control), and the gabexate group (administered gabexate mesilate 20 mg/kg), SNL was performed. At the 3rd day, mechanical allodynia was confirmed using von Frey filaments, and drugs were administered intraperitoneally daily according to the group. The paw withdrawal threshold (PWT) was examined on the 3rd, 7th, and 14th day. The expressions of p65 subunit of NF-κB, interleukin (IL)-1, IL-6, tumor necrosis factor-α, and iNOS were evaluated on the 7th and 14th day following SNL.

RESULTS

The PWT was significantly higher in the gabexate group compared with the vehicle-treated group (P < 0.05). The expressions of p65, proinflammatory cytokines, and iNOS significantly decreased in the gabexate group compared with the vehicle-treated group (P < 0.05) on the 7th day. On the 14th day, the expressions of p65 and iNOS showed lower levels, but those of the proinflammatory cytokines showed no significant differences.

CONCLUSIONS

Gabexate mesilate increased PWT after SNL and attenuate the progress of mechanical allodynia. These results seem to be involved with the anti-inflammatory effect of gabexate mesilate via inhibition of NF-κB, proinflammatory cytokines, and nitric oxide.

MicroRNA-144 relieves chronic constriction injury-induced neuropathic pain via targeting RASA1

MicroRNAs (miRNAs) have been shown to participate in development of neuropathic pain. However, the role of microRNA-144 (miR-144) in neuropathic pain remains unclear. In the present study, we established a neuropathic pain mouse model via chronic constriction injury (CCI)-induction. The successful establishment of this model was confirmed via evaluation of paw withdrawal threshold (PWT) and paw withdrawal latency (PWL). By using this model, we found that miR-144 was significantly downregulated in CCI-induced neuropathic pain mice. In addition, intrathecal injection of miR-144 agomiR alleviated mechanical and thermal hyperalgesia in neuropathic pain mice as shown by the increased of PWT and PWL. Moreover, miR-144 negatively regulated neuroinflammation by decreasing the expression of proinflammatory mediators, including TNF-α (tumor necrosis factor-α), IL (interleukin)-1β, and IL-6, thus facilitating the inhibition of neuropathic pain development. Mechanistically, RASA1 (RAS P21 Protein Activator 1) was downregulated following the injection of agomiR-144, and was verified to be a target of miR-144. Furthermore, overexpression of RASA1 reversed the inhibitory effect of miR-144 on neuropathic pain. Therefore, the present study suggested that miR-144 has the potential to be explored as therapeutic target for treatment of neuropathic pain.

Prokineticin 2 promotes and sustains neuroinflammation in vincristine treated mice: Focus on pain and emotional like behavior

Vincristine (VCR) treatment is often associated to painful neuropathy. Its development is independent from antitumoral mechanism and involves neuroinflammation. We investigated the role of the chemokine prokineticin (PK)2 in a mouse model of VCR induced neuropathy using a PK-receptors (PK-R) antagonist to counteract its development. We also evaluated emotional like deficits in VCR mice. VCR (0,1 mg/kg) was i.p. injected in C57BL/6J male mice once a day for 14 consecutive days. Pain, anxiety and depressive like behaviors were assessed in animals. PK2, PK-Rs, cytokines, neuroinflammatory markers (CD68, CD11b, GFAP, TLR4) and ATF3 were evaluated in DRG, spinal cord, prefrontal cortex and hippocampus. The PK-Rs antagonist PC1, was s.c. injected (150 μg/kg) twice a day from day 7 (hypersensitivity state) until day 14. Its effect on pain and neuroinflammation was evaluated. VCR mice developed neuropathic pain but not mood alterations. After 7 days of VCR treatment we observed a neuroinflammatory condition in DRG with high levels of PK-Rs, TLR4, CD68, ATF3 and IL-1β without relevant alterations in spinal cord. At day 14, an upregulation of PK system and a marked neuroinflammation was evident also in spinal cord. Moreover, at the same time, we observed initial alterations in supraspinal brain areas. PC1 treatment significantly counteracted neuropathic pain and blunted neuroinflammation.

Impact of caloric restriction on peripheral nerve injury-induced neuropathic pain during ageing in mice

The incidence of peripheral neuropathy development and chronic pain is strongly associated with the arrival of senescence. The gradual physiological decline that begins after the mature stage produces myelin dysregulation and pathological changes in peripheral nervous system, attributed to reduction in myelin proteins expression and thinner myelin sheath. Moreover in elder subjects, when nerve damage occurs, the regenerative processes are seriously compromised and neuropathic pain (NeP) is maintained. We previously demonstrated that caloric restriction (CR) in adult (4 months) nerve-lesioned mice was able to facilitate remyelination and axons regeneration, to have anti-inflammatory action and to prevent NeP chronification. Here, we show CR therapeutic potential on nerve injury-induced neuropathy in mice at the beginning of the senescence (12 months). Long lasting decrease in hypersensitvity induced by peripheral nerve lesion and powerful reduction in proinflammatory circulating agents have been observed. Moreover, our results evidence that CR is able to counteract the ageing-related delay in axonal regeneration, enhancing Schwann cells proliferation and accelerating recovery processes. Differently from adults, it does not affect fibres myelination. In light of a continuous growth in elderly population and correlated health problems, including metabolic disorders, the prevalence of neuropathy is enhancing, generating a significant public cost and social concern. In this context energy depletion by dietary restriction can be a therapeutic option in NeP.

Miconazole alleviates peripheral nerve crush injury by mediating a macrophage phenotype change through the NF-κB pathway

BACKGROUND

Peripheral nerve injury (PNI) causes motor and sensory defects, has strong impact on life quality and still has no effective therapy. Miconazole is one of the most widely used antifungal drugs; the aims of the study were to investigate the effects of miconazole during sciatic nerve regeneration in a mouse model of sciatic nerve crush injury.

METHODS

We established peripheral nerve crush model and investigated the effects of miconazole by multiple aspects. We further studied the potential mechanism of action of miconazole by Western blotting, fluorescence immunohistochemistry, and PCR analysis.

RESULTS

Miconazole improves the symptoms of crushed nerve by improving inflammatory cell infiltration and demyelinating myelin of sciatic nerve. Affected by miconazole, the proportion of inflammatory M1 macrophages in the distal part of the sciatic nerve was reduced, and the proportion of anti-inflammatory M2 macrophages was increased. Finally, the neuroprotective properties of miconazole may be regulated by the nuclear factor (NF)-κB pathway.

CONCLUSIONS

Our data suggest that miconazole can effectively alleviate PNI, and the mechanism involves mediating a phenotype change of M1/ M2 macrophages. Thus, miconazole may represent a potential therapeutic intervention for nerve crush injury.

High-mobility group box 1-mediated microglial activation induces anxiodepressive-like behaviors in mice with neuropathic pain

Clinical evidence indicates that major depression is a common comorbidity of chronic pain, including neuropathic pain. However, the cellular basis for chronic pain-mediated major depression remains unclear. High-mobility group box 1 protein (HMGB1) has a key role in innate immune responses and appears to be have a role in mediating diverse disorders, including neuropathic pain and depression. The current study aimed to characterize neuropathic pain-induced changes in affect over time and to determine whether HMGB1 has a role in neuropathic pain-induced changes in affect. Neuropathic pain was induced by partial sciatic nerve ligation (PSNL) in mice. Anxiodepressive-like behaviors in mice were evaluated over 10 weeks, in the social interaction, forced swim, and novelty suppressed feeding tests. Mice developed anxiodepressive-like behavior 6 to 8 weeks after induction of neuropathy. Accompanying anxiodepressive-like behavior, increased HMGB1 protein and microglia activation were observed in frontal cortex at 8 weeks after PSNL. Intracerebroventricular administration of rHMGB1 in naïve mice induced anxiodepressive-like behavior and microglia activation. Blockage of HMGB1 in PSNL mice with glycyrrhizic acid (GZA) or anti-HMGB1 antibody reduced microglia activation and anxiodepressive-like behavior. These results indicate that PSNL-induced anxiodepressive-like behavior is likely mediated by HMGB1. Furthermore, the data indicate that inhibition of HMGB1-dependent microglia activation could be a strategy for the treatment of depression associated with neuropathic pain.

Targeting prokineticin system counteracts hypersensitivity, neuroinflammation, and tissue damage in a mouse model of bortezomib-induced peripheral neuropathy

BACKGROUND

Neuropathy is a dose-limiting side effect of many chemotherapeutics, including bortezomib. The mechanisms underlying this condition are not fully elucidated even if a contribution of neuroinflammation was suggested. Here, we investigated the role of a chemokine family, the prokineticins (PKs), in the development of bortezomib-induced peripheral neuropathy (BIPN), and we used a PK receptor antagonist to counteract the development and progression of the pathology.

METHODS

Neuropathy was induced in male C57BL/6J mice by using a protocol capable to induce a detectable neuropathic phenotype limiting systemic side effects. The presence of allodynia (both mechanical and thermal) and thermal hyperalgesia was monitored over time. Mice were sacrificed at two different time points: 14 and 28 days after the first bortezomib (BTZ) injection. At these times, PK system activation (PK2 and PK-Rs), macrophage and glial activation markers, and cytokine production were evaluated in the main station involved in pain transmission (sciatic nerve, DRG, and spinal cord), and the effect of a PK receptors antagonist (PC1) on the same behavioral and biochemical parameters was assessed. Structural damage of DRG during BTZ treatment and an eventual protective effect of PC1 were also evaluated.

RESULTS

BTZ induces in mice a dose-related allodynia and hyperalgesia and a progressive structural damage to the DRG. We observed a precocious increase of macrophage activation markers and unbalance of pro- and anti-inflammatory cytokines in sciatic nerve and DRG together with an upregulation of GFAP in the spinal cord. At higher BTZ cumulative dose PK2 and PK receptors are upregulated in the PNS and in the spinal cord. The therapeutic treatment with the PK-R antagonist PC1 counteracts the development of allodynia and hyperalgesia, ameliorates the structural damage in the PNS, decreases the levels of activated macrophage markers, and prevents full neuroimmune activation in the spinal cord.

CONCLUSIONS

PK system may be a strategical pharmacological target to counteract BTZ-induced peripheral neuropathy. Blocking PK2 activity reduces progressive BTZ toxicity in the DRG, reducing neuroinflammation and structural damage to DRG, and it may prevent spinal cord sensitization.

A single peri-sciatic nerve administration of the adenosine 2A receptor agonist ATL313 produces long-lasting anti-allodynia and anti-inflammatory effects in male rats

Neuropathic pain is a widespread problem which remains poorly managed by currently available therapeutics. Peripheral nerve injury and inflammation leads to changes at the nerve injury site, including activation of resident and recruited peripheral immune cells, that lead to neuronal central sensitization and pain amplification. The present series of studies tested the effects of peri-sciatic nerve delivery of single doses of adenosine 2A receptor (A_2aR) agonists on pain and neuroinflammation. The data provide converging lines of evidence supportive that A_2aR agonism at the site of peripheral nerve injury and inflammation is effective in suppressing ongoing neuropathic pain. After A_2aR agonism resolved neuropathic pain, a return of pain enhancement (allodynia) was observed in response to peri-sciatic injection of H-89, which can inhibit protein kinase A, and by peri-sciatic injection of neutralizing antibody against the potent anti-inflammatory cytokine interleukin-10. A_2aR agonist actions at the nerve injury site suppress neuroinflammation, as reflected by decreased release of interleukin-1β and nitric oxide, as well as decreased sciatic expression of markers of monocytes/macrophages and inducible nitric oxide synthase. Taken together, the data are supportive that A_2aR agonists, acting at the level of peripheral nerve injury, may be of therapeutic value in treating chronic pain of neuroinflammatory origin.

Inhibition of the protein kinase IKKepsilon attenuates neuropathic pain in mice

Inhibitor-kappaB kinase epsilon (IKKε, Ikbke) constitutes an NF-κB activating kinase with high homology to the classical I-κB kinase subunits, IKKα and IKKβ. It is expressed in nociceptive neurons in the spinal cord and in dorsal root ganglia (DRG) and involved in inflammatory nociception. Under inflammatory conditions, IKKε deficient mice show significantly less nociceptive behavior in comparison to wild type mice associated with reduced activation of NF-κB and attenuated NF-κB-dependent gene expression. The role of IKKε in neuropathic pain has not been investigated so far. We applied the spared nerve injury (SNI) model of neuropathic pain in mice and found an increased expression of IKKε in the spinal cord, the DRGs and the sciatic nerve after induction of neuropathy. Genetic depletion of IKKε or pharmacological inhibition by amlexanox led to a significant reduction of mechanical hyperalgesia and cold allodynia in comparison to control mice. Transcription factor ELISA indicated that the effects are mediated by reduced activation of NF-κB. Furthermore, immunofluorescence staining, qPCR and Western Blot analyses revealed that the decreased pain-like behavior was associated with a reduced activation of microglia, diminished expression of c-fos as well as a decreased activation of MAP-Kinases. In summary, we conclude that IKKε modulates mechanisms of neuropathic pain by activating NF-κB. The administration of IKKε inhibitors might therefore constitute a new and promising approach for the therapy of neuropathic pain.

Pro-resolving mediator maresin 1 ameliorates pain hypersensitivity in a rat spinal nerve ligation model of neuropathic pain

Background

Pro-resolving mediators (PRMs) are considered as emerging analgesics for chronic pain. Maresin 1 (MaR1) is a newly identified member of PRMs, and recent studies implicate its potential role in some pain conditions. As the function of MaR1 in neuropathic pain remains unclear, we investigated the effects of MaR1 on pain hypersensitivity and the underlying mechanism using a rat spinal nerve ligation (SNL) model of neuropathic pain.

Materials and methods

MaR1 (100 ng/10 μL) or commensurable artificial cerebrospinal fluid was delivered via intrathecal catheter from days 3 to 5 post-SNL followed by assessment of mechanical allodynia and thermal hyperalgesia. Ipsilateral L4–L5 spinal cord tissue was collected on day 7 post-SNL and assessed by Western blotting, enzyme-linked immunosorbent assay or immunohistochemistry.

Results

Intrathecal MaR1 significantly attenuated mechanical allodynia and thermal hyperalgesia from day 5 to day 7 post-SNL, which was associated with decreased spinal levels of glial markers, GFAP and IBA1. It was also found that intrathecal MaR1 downregulated phosphorylation levels of NF-κB p65 and its nuclear translocation, as well as decreased protein levels of pro-inflammatory cytokines, TNF-α, IL-1β and IL-6. Further, MaR1 treatment restored PSD95 and synapsin II levels, suggesting that MarR1 also protected synaptic integrity.

Conclusion

Our results indicate that MaR1 ameliorates the SNL-induced neuropathic pain by regulating glial activities and pro-inflammatory cytokines release. The present study offers insight into the potential of MaR1 as a novel intervention to ameliorate neuropathic pain.

Tanshinone IIA Attenuates Diabetic Peripheral Neuropathic Pain in Experimental Rats via Inhibiting Inflammation

Diabetic peripheral neuropathic pain (DPNP) is a common and intractable complication of diabetes. Conventional therapies are always not ideal; development of novel drugs is still needed to achieve better pain relief. Recent evidences have demonstrated that inflammation is involved in the onset and maintenance of DPNP. The anti-inflammatory property of Tanshinone IIA (TIIA) makes it a promising candidate to block or alter the pain perception. This study was conducted to investigate whether TIIA could attenuate DPNP in streptozotocin- (STZ-) induced rats model and its potential mechanisms. TIIA was administered to STZ-induced diabetic rats at the dose of 40 mg/kg once a day for 3 weeks. The effects of TIIA on thermal hyperalgesia and mechanical allodynia were investigated using behavioral tests. The mRNA level and expression of interleukin- (IL-) 1β, interleukin- (IL-) 6, tumor necrosis factor- (TNF-) α, and interleukin- (IL-) 10 in the fourth to sixth segments of the dorsal root ganglion (L4–6 DRG) were detected by quantitative real-time PCR (qPCR) and Western blot. TIIA treatment significantly attenuated mechanical allodynia and thermal hyperalgesia in diabetic rats. In addition, the expression of the proinflammatory cytokines IL-1β, IL-6, and TNF-α was inhibited, and the level of the anti-inflammatory cytokine IL-10 was increased by TIIA. This study demonstrated that TIIA has significant antiallodynic and antihyperalgesic effects in a rat model of STZ-induced DPNP, and the effect may be associated with its anti-inflammation property.

Low-dose NSAIDs reduce pain via macrophage targeted nanoemulsion delivery to neuroinflammation of the sciatic nerve in rat

Neuroinflammation involving macrophages elevates Prostaglandin E₂, associated with neuropathic pain. Treatment with non-steroidal anti-inflammatory drugs (NSAIDs) inhibits cyclooxygenase, reducing PGE₂. However, NSAIDs cause physiological complications. We developed nanoemulsions incorporating celecoxib and near infrared dye. Intravenous injected nanoemulsion is incorporated into monocytes that accumulate at the injury; revealed in live animals by fluorescence. A single dose (celecoxib 0.24 mg/kg) provides targeted delivery in chronic constriction injury rats, resulting in significant reduction in the visualized inflammation, infiltration of macrophages, COX-2 and PGE₂. Animals exhibit relief from hypersensitivity persisting at least four-days. The total body burden of drug is reduced by >2000 fold over oral drug delivery.

Local Application of Ultrasound Attenuates Neuropathic Allodynia and Proinflammatory Cytokines in Rats After Thoracotomy

BACKGROUND AND OBJECTIVES

We aimed to investigate the effect of therapeutic ultrasound (TU) on pain sensitivity and the concentration inflammatory cytokines in a thoracotomy rat model.

METHODS

Rats were distributed randomly into 4 groups: (1) sham operated, (2) thoracotomy and rib retraction (TRR), (3) TRR rats that received TU (TRR + TU-1), and (4) TRR rats that received TU with the ultrasound turned off (TRR + TU-0). Ultrasound was set at 1-MHz frequency (1.0-W/cm intensity and 100% duty cycle for 5 minutes), began on postoperative day (POD) 10, and then continued once per day, 5 days a week for 3 weeks.

RESULTS

The TRR and TRR + TU-0 rats encountered tactile hypersensitivity from PODs 10 to 28. Mechanical withdrawal thresholds were increased (all P < 0.05) following 5 days of TU, but thresholds remained significantly lower than baseline values. Therapeutic ultrasound increased the subcutaneous, but not body temperature. All groups receiving TRR demonstrated an increase in concentration of interleukin 1β and tumor necrosis factor α (TNF-α) on POD 14; however, the rise in TNF-α concentration was less in the TU-treated group than in the others. The decrease in concentration was greatest in the TRR + TU-1 group and similar between the TRR and TRR + TU-0 groups.

CONCLUSIONS

Mechanical allodynia was partially resolved with TU. Tissue temperature increased with ultrasound, while TU restricted the up-regulation of interleukin 1β and TNF-α around the injured intercostal nerve.

Conditioned Medium of Bone Marrow-Derived Mesenchymal Stromal Cells as a Therapeutic Approach to Neuropathic Pain: A Preclinical Evaluation

Neuropathic pain is a type of chronic pain caused by injury or dysfunction of the nervous system, without effective therapeutic approaches. Mesenchymal stromal cells (MSCs), through their paracrine action, have great potential in the treatment of this syndrome. In the present study, the therapeutic potential of MSC-derived conditioned medium (CM) was investigated in a mouse model of neuropathic pain induced by partial sciatic nerve ligation (PSL). PSL mice were treated by endovenous route with bone marrow-derived MSCs (1 × 10⁶), CM, or vehicle. Gabapentin was the reference drug. Twelve hours after administration, neuropathic mice treated with CM exhibited an antinociceptive effect that was maintained throughout the evaluation period. MSCs also induced nonreversed antinociception, while gabapentin induced short-lasting antinociception. The levels of IL-1β, TNF-α, and IL-6 were reduced, while IL-10 was enhanced on sciatic nerve and spinal cord by treatment with CM and MSCs. Preliminary analysis of the CM secretome revealed the presence of growth factors and cytokines likely involved in the antinociception. In conclusion, the CM, similar to injection of live cells, produces a powerful and long-lasting antinociceptive effect on neuropathic pain, which is related with modulatory properties on peripheral and central levels of cytokines involved with the maintenance of this syndrome.

Analgesic effect of AG490, a Janus kinase inhibitor, on oxaliplatin-induced acute neuropathic pain

Neuropathic pain often occurs during chemotherapy with oxaliplatin. AG490 has been shown to exert an antagonistic effect on inflammatory pain, but its effect on oxaliplatin-induced neuropathic pain remains poorly understood. This study sought to observe the analgesic effect of AG490 on acute neuropathic pain induced by a single oxaliplatin treatment and to address the possible mechanism. In this study, we established a model of oxaliplatin-induced acute neuropathic pain by intraperitoneal injection of 6 mg/kg oxaliplatin. On day 2 after injection, models were intraperitoneally injected with 1, 5, or 10 mg/kg AG490. Paw withdrawal threshold to mechanical stimuli and tail withdrawal latency to cold stimuli were determined. Western blot assay was performed to detect the expression of spinal phosphorylated signal transducer and activator of transcription 3 (p-STAT3). Immunohistochemistry was used to determine the immunoreactivity of p-STAT3 and interleukin-6. Results demonstrated that paw withdrawal threshold and tail withdrawal latency were significantly increased by the treatment of AG490 in rats. There was no significant difference in the effect among the different doses of AG490. AG490 10 mg/kg decreased the expression of p-STAT3, the immunoreactivity of p-STAT3 and interleukin-6 in spinal cord of acute neuropathic pain rats. These findings confirm that AG490 can attenuate oxaliplatin-induced acute neuropathic pain and is associated with the inhibition in the JAK/STAT3 signaling pathway.

Red nucleus interleukin-6 participates in the maintenance of neuropathic pain through JAK/STAT3 and ERK signaling pathways

We previously reported that interleukin-6 (IL-6) in the red nucleus (RN) is up-regulated at 3weeks after spared nerve injury (SNI), and plays facilitated role in the later maintenance of neuropathic pain. The current study aimed to reveal the roles of different signaling pathways, including Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3), extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositide 3-kinase/protein kinase B (PI3K/AKT), in RN IL-6-mediated pain modulation. In accord with the increase of IL-6 in the RN following SNI, the protein levels of phospho-STAT3 (p-STAT3), p-ERK and p-JNK were also up-regulated in the RN contralateral to the nerve injury side at 3weeks after SNI. The increases of p-STAT3 and p-ERK (but not p-JNK) were associated with IL-6 and could be blocked by anti-IL-6 antibody. Microinjection of JAK2 inhibitor AG490, ERK inhibitor PD98059 and also JNK inhibitor SP600125 into the RN significantly increased the paw withdrawal threshold (PWT) and alleviated SNI-induced mechanical allodynia. Further studies showed that microinjection of recombinant rat IL-6 (rrIL-6, 20ng) into the RN of normal rats significantly decreased the PWT of rats and increased the local protein levels of p-STAT3 and p-ERK, but not p-JNK. Pre-treatment with AG490 and PD98059 could prevent IL-6-induced mechanical allodynia. Whereas, p-p38 MAPK and p-AKT did not show any expression changes in the RN of rats with SNI or rats treated with rrIL-6. These results suggest that RN IL-6 participates in the later maintenance of SNI-induced neuropathic pain and plays facilitated role through activating JAK/STAT3 and ERK signaling pathways.