Search

The systemic administration of interleukin-16 (IL-16, 3-30 ng/kg) induced thermal hyperalgesia in mice, that was prevented by the acute injection of an anti-CD4 antibody (1 µg/kg), the depletion of circulating white blood cells by cyclophosphamide or the specific reduction of circulating CD4 + cells provoked by a high dose of an anti-CD4 antibody (30 µg/mouse, 24 h before). IL-16-induced hyperalgesia was locally inhibited after intraplantar (i.pl.) administration of the non-selective cyclooxygenase (COX) inhibitor diclofenac, the COX-1 inhibitor SC-560, the COX-2 inhibitor celecoxib, the TRPV1 antagonist capsazepine or the TRPA1 antagonist HC030031, thus demonstrating that prostaglandins and TRP channels are involved in this effect. The i.pl. administration of low doses of IL-16 (0.1-1 ng) evoked local hyperalgesia suggesting the possibility that IL-16 could participate in hypernociception associated to local tissue injury. Accordingly, IL-16 concentration measured by ELISA was increased in paws acutely inflamed with carrageenan or chronically inflamed with complete Freund´s adjuvant (CFA). This augmentation was reduced after white cell depletion with cyclophosphamide or neutrophil depletion with an anti-Ly6G antibody. Immunofluorescence and flow cytometry experiments showed that the increased concentration of IL-16 levels found in acutely inflamed paws is mainly related to the infiltration of IL-16 + neutrophils, although a reduced number of IL-16 + lymphocytes was also detected in paws inflamed with CFA. Supporting the functional role of IL-16 in inflammatory hypernociception, the administration of an anti-IL-16 antibody dose-dependently reduced carrageenan- and CFA-induced thermal hyperalgesia and mechanical allodynia. The interest of IL-16 as a target to counteract inflammatory pain is suggested., (© 2024. The Author(s).)

Aims: To explore the mechanisms involved in the transformation of analgesia produced by low doses of CCL4 (pg/kg) to hyperalgesia when higher doses (ng/kg) are administered to mice., Main Methods: The unilateral hot plate test was used to assess thermal nociception. CD3 + , CD4 + or CD8 + blood cells were depleted with selective antibodies. Expression of CCR5 and IL-16 in lymphocytes was studied by flow cytometry and IL-16 blood levels were measured by ELISA. IL-16 and CD8 were detected by immunofluorescence., Key Findings: IL-16 and CCR5 expression were demonstrated in CD4 + and CD8 + T-lymphocytes by flow cytometry. Furthermore, CCL4-induced hyperalgesia was abolished by reducing circulating T-lymphocyte levels or by selectively depleting CD4 + lymphocytes. In contrast, when the anti-CD4 antibody was acutely administered, CCL4 induced analgesia instead of hyperalgesia. A similar response was obtained when administering A-770041, that prevents CD4-mediated CCR5 desensitization by inhibiting p56 lck kinase. As occurred with the analgesic effect evoked by low doses of CCL4, analgesia evoked by combining CCL4 and A-770041 was reverted by naloxone, naltrindole or an anti-met-enk antibody. Interestingly, flow cytometry assays showed that the number of CD8 + , but not CD4 + , T-cells expressing IL-16 is reduced after the acute administration of CCL4, a result compatible with the description that CD8 + -lymphocytes can rapidly release preformed IL-16. Accordingly, the rise in IL-16 blood concentration evoked by CCL4 was prevented after CD8 + lymphocyte depletion., Significance: CCL4-evoked hyperalgesia is related to the desensitization of CCR5 in CD4 + T-cells and to the release of IL-16 from CD8 + lymphocytes., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

The cool sensor transient receptor potential melastatin channel 8 (TRPM8) is highly expressed in trigeminal and dorsal root ganglia, playing a key role in cold hypersensitivity associated to different peripheral neuropathies. Moreover, these channels are aberrantly expressed in different cancers, and seem to participate in tumor progression, survival and invasion. Accordingly, the search for potent and selective TRPM8 modulators attracted great interest in recent years. We describe new heterocyclic TRPM8 antagonist chemotypes derived from N-cloroalkyl phenylalaninol-Phe conjugates. The cyclization of these conjugates afforded highly substituted β-lactams and/or 2-ketopiperazine (KP) derivatives, with regioselectivity depending on the N-chloroalkyl group and the configuration. These derivatives behave as TRPM8 antagonists in the Ca 2+ microfluorometry assay, and confirmed electrophysiologically for the best enantiopure β-lactams 24a and 29a (IC 50 , 1.4 and 0.8 µM). Two putative binding sites by the pore zone, different from those found for typical agonists and antagonists, were identified by in silico studies for both β-lactams and KPs. β-Lactams 24a and 29a display antitumor activity in different human tumor cell lines (micromolar potencies, A549, HT29, PSN1), but correlation with TRPM8 expression could not be established. Additionally, compound 24a significantly reduced cold allodynia in a mice model of oxaliplatin-induced peripheral neuropathy.

As recently described, the administration of extremely low doses (pg/kg) of CCL4 (Macrophage inflammatory protein 1β, MIP-1β) can induce antinociceptive effects in mice (García-Domínguez et al., 2019b). We describe here that hydrodynamic delivery of a plasmid containing CCL4 cDNA provokes a biphasic response consisting in an initial thermal hyperalgesic reaction for 8 days followed by analgesia at days 10-12, being both responses blocked after the administration of the CCR5 antagonist DAPTA. Both the luminiscence evoked in liver after the administration of a plasmid containing CCL4 and luciferase cDNAs and the hepatic concentration of CCL4 measured by ELISA were maximal 4 days after plasmid administration and markedly diminished at day 10. A dose-effect curve including a wide dose range of exogenous CCL4 revealed thermal analgesia after the administration of 10-100 pg/kg whereas 1000 times higher doses (30-100 ng/kg) induced, instead, thermal hyperalgesia inhibited by DAPTA. This hyperalgesia was absent in mice with reduced white blood cells after cyclophosphamide treatment, thus supporting the involvement of circulating leukocytes. A multiarray bioluminescent assay revealed increased plasma levels of IL-1α, CCL2, CXCL1, CXCL13, IL-16 and TIMP-1 in mice treated with 100 ng/kg of CCL4. The hyperalgesic response evoked by CCL4 was prevented by IL-1R, CXCR2 or CCR2 antagonists or by the neutralization of CXCL13 or IL-16, but not TIMP-1, with selective antibodies. The administration of the anti-IL-16 antibody was the unique treatment able to convert hyperalgesia evoked by 100 ng/kg of CCL4 in an analgesic effect. The ability of IL-16 to evoke hypernociception was confirmed by studying the response to its exogenous administration (10-30 ng/kg). In summary, the present results demonstrate that CCL4 induces a dual modulation of nociception and describe some mechanisms involved in the hyperalgesic response evoked by this chemokine., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

We show here that the intraplantar administration of CCL5 in mice produces hyperalgesia at low doses but activates compensatory antinociceptive mechanisms at doses slightly higher. Thus, the injection of 3-10ng of CCL5 evoked thermal hyperalgesia through the activation of CCR1 and CCR5 receptors, as demonstrated by the inhibitory effect exerted by the selective antagonists J113863 (0.01-0.1μg) and DAPTA (0.3-3μg), respectively. The prevention of this hyperalgesia by diclofenac (1-10μg), the inhibitors of COX-1 SC-560 (0.1-1μg) or COX-2 celecoxib (1-5μg), the TRPV1 antagonist capsazepine (0.03-0.3μg) or the TRPA1 antagonist HC030031 (10-50μg) demonstrates the involvement of prostaglandin synthesis and TRP sensitization in CCL5-evoked hyperalgesia. Doses of CCL5 higher than 17μg did not evoke hyperalgesia. However, this effect was restored by the administration of naloxone-methiodide (5μg), nor-binaltorphimine (10mg/kg) or an anti-dynorphin A antibody (0.62-2.5ng). The administration of 30ng of CCL5 also induced hyperalgesia in mice with reduced number of circulating white blood cells in response to cyclophosphamide or with selective neutrophil depletion induced by an anti-Ly6G antibody. In fact, the number of neutrophils present in paws treated with 30ng of CCL5 was greater than in paws receiving the administration of the hyperalgesic dose of 10ng. Finally, the expression of the endogenous opioid peptide dynorphin A was demonstrated by double immunofluorescence assays in these neutrophils attracted by CCL5. These results support previous data describing the hyperalgesic properties of CCL5 and constitute the first indication that a chemokine of the CC group can activate endogenous analgesic mechanisms., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Chemokine CCL2, also known as monocyte chemoattractant protein-1 (MCP-1), is a molecule that in addition to its well-established role in chemotaxis can also act as nociceptor sensitizer. The upregulation of this chemokine in inflamed tissues could suggest its involvement in inflammatory hypernociception. Thus, we have measured CCL2 levels in mice with acute or chronic inflammation due to the intraplantar (i.pl.) injection of carrageenan or complete Freund's adjuvant (CFA), respectively, and we have studied whether inflammatory hyperalgesia or allodynia could be attenuated by blocking CCR2 receptors or neutralizing CCL2 with an anti-CCL2 antibody. A remarkable increase in CCL2 concentration was detected by ELISA in paw homogenates coming from carrageenan- or CFA-inflamed mice, being its expression mainly localized in macrophages, as shown by immunohistochemical assays. The s.c. (0.3-3 mg/kg) or i.pl. (0.3-3 μg) administration of the CCR2 antagonist, RS 504393, dose dependently inhibited thermal hyperalgesia measured in acutely or chronically inflamed mice, whereas s.c. administration of this drug did not reduce inflammatory mechanical allodynia. Furthermore, the inhibition of inflammatory hyperalgesia after the administration of an anti-CCL2 antibody (0.1-1 μg; i.pl.) suggests that CCL2 could be the endogenous chemokine responsible for CCR2-mediated hyperalgesic effects. Besides, the acute administration of the highest antihyperalgesic dose of RS 504393 assayed did not reduce paw tumefaction or modify the presence of inflammatory cells. These results indicate that the blockade of the CCL2/CCR2 system can counteract inflammatory hyperalgesia, being this antinociceptive effect unrelated to a decrease in the inflammatory reaction., (© 2016 Société Française de Pharmacologie et de Thérapeutique.)

The hypernociceptive role played by the chemokine CCL2, and its main receptor, CCR2, in pathological settings is being increasingly recognized. We aimed to characterize the involvement of spinal CCL2 in the hyperalgesia due to the intratibial inoculation of fibrosarcoma NCTC 2472 cells in mice. The intrathecal (i.t.) administration of the CCR2 antagonist RS 504393 (1–3 μg) or an anti-CCL2 antibody inhibited tumoral hyperalgesia. No change in the expression of spinal CCR2 was detected by western blot, whereas immunohistochemical experiments demonstrated increased CCL2 staining at the superficial laminae of the spinal cord ipsilateral to the tumor. This spinal CCL2 does not seem to be released from nociceptors since CCL2 mRNA and CCL2 levels in DRGs, as measured by RT-PCR and ELISA, remain unmodified in tumor-bearing mice. In contrast, immunohistochemical assays demonstrated the spinal up-regulations of GFAP and Iba-1, respective markers of astroglia and microglia, and the expression of CCL2 in both types of glial cells at the superficial laminae of the spinal cord of tumor-bearing mice. Finally, since CCL2 could induce astroglial or microglial activation, we studied whether the blockade of CCR2 could inhibit the increased spinal glial expression. GFAP, but not Iba-1, up-regulation was reduced in tumor-bearing mice treated for 3 days with i.t. RS 504393, indicating that spinal CCL2 acts as an astroglial activator in this setting. The participation at spinal level of CCL2/CCR2 in tumoral hypernociception, together with its previously described involvement at periphery, makes attractive the modulation of this system for the alleviation of neoplastic pain.

The participation of the chemokine CCL2 (monocyte chemoattractant protein-1) in inflammatory and neuropathic pain is well established. Furthermore, the release of CCL2 from a NCTC 2472 cells-evoked tumor and its involvement in the upregulation of calcium channel α2δ1 subunit of nociceptors was demonstrated. In the present experiments, we have tried to determine whether the increase in CCL2 levels is a common property of painful tumors and, in consequence, the administration of a chemokine receptor type 2 (CCR2) antagonist can inhibit tumoral hypernociception. CCL2 levels were measured by ELISA in the tumoral region of mice intratibially inoculated with NCTC 2472 or B16-F10 cells, and the antihyperalgesic and antiallodynic effects evoked by the administration of the selective CCR2 antagonist RS 504393 were assessed. Cultured NCTC 2472 cells release CCL2 and their intratibial inoculation evokes the development of a tumor in which CCL2 levels are increased. Moreover, the systemic or peritumoral administration of RS 504393 inhibited thermal and mechanical hyperalgesia, but not mechanical allodynia evoked after the inoculation of these cells. Thermal hyperalgesia was also inhibited by the peritumoral administration of a neutralizing CCL2 antibody. In contrast, no change in CCL2 levels was observed in mice inoculated with B16-F10 cells, and RS 504393 did not inhibit the hypernociceptive reactions evoked by their intratibial inoculation. The peripheral release of CCL2 is involved in the development of thermal and mechanical hyperalgesia, but not mechanical allodynia evoked by the inoculation of NCTC 2472 cells, whereas this chemokine seems unrelated to the hypernociception induced by B16-F10 cells.

Although previous studies describe the up-regulation of purinergic P2X(3) receptors expressed at peripheral nociceptive fibers in experimental painful neoplastic processes, the analgesic efficacy of P2X(3) receptor antagonists has not been tested in these settings. We study here the effect of the P2X(3) receptor antagonist, A-317491, on thermal hyperalgesia produced by the intratibial inoculation of NCTC 2472 fibrosarcoma cells to C3H/HeJ mice. The peritumoral administration of A-317491 (10-100 microg) dose-dependently attenuated osteosarcoma-induced thermal hyperalgesia without modifying thermal latencies measured in the contralateral paws. This antihyperalgesic effect was inhibited by the coadministration of naloxone-methiodide (0.1-1 microg) or the systemic injection of the selective mu-opioid receptor antagonist cyprodime (1 mg/kg), demonstrating the involvement of peripheral mu-opioid receptors. Furthermore, the antihyperalgesic effect induced by A-317491, was antagonised by the coadministration of an anti-enkephalin antibody supporting the participation of endogenous enkephalins. Consistent with this result, the antihyperalgesic effect induced by A-317491 was dramatically enhanced by the administration of an enkephalin-degrading inhibitor, Debio 0827, as demonstrated by isobolographic analysis. This synergism opens the theoretical possibility that the combination of both types of drugs could be useful to counteract some nociceptive symptoms derived from tumor development.

Background: This study examined the development of chronic pain, a cardinal symptom of rheumatoid arthritis (RA), in mice with antigen- and collagen-induced arthritis (ACIA). Since the role of CD8+ T cells in arthritis is controversial, we investigated the consequences of CD8-depletion on arthritis development and opioid modulation of pain in this novel model of chronic autoimmune arthritis.Methods: Disease severity in control and CD8-depleted animals was determined by histological assessment of knee-joint sections and measurement of autoantibody formation. Pain was evaluated by measuring mechanical allodynia and thermal hyperalgesia in von Frey and Hargreaves tests, respectively. The production and release of endogenous opioids and inflammatory cytokines was assessed in immunoassays.Results: In ACIA, mice display persistent mechanical allodynia and thermal hyperalgesia for more than 2 months after induction of arthritis. The blockade of peripheral opioid receptors with naloxone-methiodide (NLXM) transiently increased thermal hyperalgesia, indicating that endogenous opioid peptides were released in the arthritic joint to inhibit pain. CD8+ T cell depletion did not affect autoantibody formation or severity of joint inflammation, but serum levels of the pro-inflammatory cytokines TNFα and IL-17 were increased. The release of opioid peptides from explanted arthritic knee cells and the NLXM effect were significantly reduced in the absence of CD8+ T cells.Conclusions: We have successfully modeled the development of chronic pain, a hallmark of RA, in ACIA. Furthermore, we detected a yet unknown protective role of CD8+ T cells in chronic ACIA since pro-inflammatory cytokines rose and opioid peptide release decreased in the absence of these cells. [ABSTRACT FROM AUTHOR]

Background The first line pharmacological treatment of cancer pain is morphine and surrogates but a significant pain relief and a reduction of the side-effects of these compounds makes it necessary to combine them with other drugs acting on different targets. The aim of this study was to measure the antinociceptive effect on cancer-induced bone pain resulting from the association of the endogenous opioids enkephalin and non-opioid analgesic drugs. For this purpose, PL265 a new orally active single dual inhibitor of the two degrading enkephalins enzymes, neprilysin (NEP) and aminopeptidase N (APN) was used. It strictly increased the levels of enkephalin at their sites of releases. The selected non-opioid compounds are: gabapentin, A-317491 (P2X 3 receptor antagonist), ACEA (CB1 receptor antagonist), AM1241 (CB2 receptor antagonist), JWH-133 (CB2 receptor antagonist), URB937 (FAAH inhibitor), and NAV26 (Nav1.7 channel blocker). Methods Experiments . Experiments were performed in 5–6 weeks old (26–33 g weight) C57BL/6 mice. Cell culture and cell inoculation. B16-F10 melanoma cells were cultured and when preconfluent, treated and detached. Finally related cells were resuspended to obtain a concentration of 2 × 10 6 cells/100 μL. Then 10 5 cells were injected into the right tibial medullar cavity. Control mice were treated by killed cells by freezing. Behavioural studies . Thermal withdrawal latencies were measured on a unilatered hot plate (UHP) maintained at 49 ± 0.2 °C. Mechanical threshold values were obtained by performing the von Frey test using the “up and down” method. To evaluate the nature (additive or synergistic) of the interactions between PL265 and different drugs, an isobolographic analysis following the method described by Tallarida was performed. Results The results demonstrate the ability of PL265, a DENKI that prevents the degradation of endogenous ENKs, to counteract cancer-induced bone thermal hyperalgesia in mice, by exclusively stimulating peripheral opioid receptors as demonstrated by used of an opioid antagonist unable to enter the brain. The development of such DENKIs, endowed with druggable pharmacokinetic characteristics, such as good absorption by oral route, can be considered as an important step in the development of much needed novel antihyperalgesic drugs. Furthermore, all the tested combinations resulted in synergistic antihyperalgesic effects. As shown here, the greatest synergistic antinociceptive effect (doses could be lowered by 70%) was produced by the combination of PL265 with the P2X 3 receptor antagonist (A-317491), cannabinoid CB1 receptor agonist (exogenous, ACEA and endogenous URB937-protected-AEA) and Na v 1.7 blocker (NAV26) whose mechanism of action involves the direct activation of the enkephalinergic system. Conclusions These multi-target-based antinociceptive strategies using combinations of non-opioid drugs with dual inhibitors of enkephalin degrading enzymes may bring therapeutic advantages in terms of efficacy and safety by allowing the reduction of doses of one of the compounds or of both, which is of the utmost interest in the chronic treatment of cancer pain. Implications This article presents synergistic antinociceptive effect produced by the combination of PL265 with non-opioid analgesic drugs acting via unrelated mechanisms. These multi-target-based antinociceptive strategies may bring therapeutic advantages by allowing the reduction of doses, which is of great interest in the chronic treatment of cancer pain. [ABSTRACT FROM AUTHOR]

Chemokines are chemotactic cytokines whose involvement in nociceptive processing is being increasingly recognized. Based on the previous description of the involvement of CC chemokine receptor type 1 ( CCR1) in pathological pain, we have assessed the participation of CCR1 and its endogenous ligands CCL3 and CCL5 in hyperalgesia and allodynia in mice after acute inflammation with carrageenan and chronic inflammation with complete Freund's adjuvant ( CFA). The subcutaneous administration of the CCR1 antagonist J113863 (3-30 mg/kg; 30 min. before) dose dependently inhibited carrageenan- and CFA-evoked thermal hyperalgesia and mechanical allodynia produced by CFA, but not by carrageenan. The maximal dose of J113863 did not modify the increase in paw thickness induced by carrageenan or CFA. An almost ten times augmentation of CCL3 levels was detected by ELISA assays in both carrageenan and CFA paws, but not in spinal cords of inflamed mice, whereas CCL5 concentrations remained unaltered. Accordingly, a marked increase of CCL3 mRNA expression was observed in inflamed paws, with CCL3 protein detected in neutrophils and macrophages by immunohistochemical experiments. The intraplantar administration of an anti- CCL3 antibody (0.3-3 μg) blocked thermal hyperalgesia in carrageenan- and CFA-inflamed mice as well as CFA-evoked mechanical allodynia. Our data suggest that the increased concentrations of CCL3 present in inflamed tissues can be involved in acute and chronic inflammatory hyperalgesia as well as in chronic mechanical allodynia, and that these hypernociceptive symptoms can be counteracted by its neutralization with an antibody or by the blockade of CCR1 receptors. [ABSTRACT FROM AUTHOR]

The newly designed fentanyl derivative [(±)-N-(3-fluoro-1-phenethylpiperidine-4-yl)-N-phenyl propionamide] (NFEPP) was recently shown to produce analgesia selectively via peripheral mu-opioid receptors (MOR) at acidic pH in rat inflamed tissues. Here, we examined the pH-dependency of NFEPP binding to brain MOR and its effects on bone cancer-induced pain in mice. The IC50 of NFEPP to displace bound [3H]-DAMGO was significantly higher compared to fentanyl at pH 7.4, but no differences were observed at pH 5.5 or 6.5. Intravenous NFEPP (30–100 nmol/kg) or fentanyl (17–30 nmol/kg) inhibited heat hyperalgesia in mice inoculated with B16-F10 melanoma cells. The peripherally-restricted opioid receptor antagonist naloxone-methiodide reversed the effect of NFEPP (100 nmol/kg), but not of fentanyl (30 nmol/kg). The antihyperalgesic effect of NFEPP was abolished by a selective MOR- (cyprodime), but not delta- (naltrindole) or kappa- (nor-binaltorphimine) receptor antagonists. Ten-fold higher doses of NFEPP than fentanyl induced maximal antinociception in mice without tumors, which was reversed by the non-restricted antagonist naloxone, but not by naloxone-methiodide. NFEPP also reduced heat hyperalgesia produced by fibrosarcoma- (NCTC 2472) or prostate cancer-derived (RM1) cells. These data demonstrate the increased affinity of NFEPP for murine MOR at low pH, and its ability to inhibit bone cancer-induced hyperalgesia through peripheral MOR. In mice, central opioid receptors may be activated by ten-fold higher doses of NFEPP. [ABSTRACT FROM AUTHOR]