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ARA 290, a peptide derived from the tertiary structure of erythropoietin, produces long-term relief of neuropathic pain coupled with suppression of the spinal microglia response.

Swartjes M, van Velzen M, Niesters M, Aarts L, Brines M, Dunne A, Cerami A, Dahan A - Mol Pain (2014)

Bottom Line: ARA290 exerted a dose-response effect by significantly reducing mechanical allodynia up to 20 weeks when compared to vehicle.The reduction of cold allodynia was significant up to 20 weeks for the doses 3, 10, 30 and 60 μg/kg when compared to vehicle.In group 1, significant microglia reactivity was observed in the L5 segment of the spinal cord of animals treated with vehicle when compared to sham operated, while animals treated with 10 or 30 μg/kg did not show a increase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesiology, Leiden University Medical Center, P5-Q, 2300 RC Leiden, The Netherlands. a.dahan@lumc.nl.

ABSTRACT

Background: Neuropathic pain is a difficult to treat disorder arising from central or peripheral nervous system lesions. The etiology of neuropathic pain consists of several overlapping pathways converging into an exaggerated pain state with symptoms such as allodynia and hyperalgesia. One of these pathways involves activation of spinal cord microglia and astrocytes, which drive and maintain the inflammatory response following the lesion. These cells are a potential target for drugs for neuropathic pain relief. In this current study, we investigated the dose-effect relationship of the tissue protective peptide ARA 290, derived from the tertiary structure of erythropoietin, on allodynia and concurrent spinal cord microglia and astrocytes.

Results: Following a spared nerve injury in rats, vehicle or ARA290 (administered in either one of 4 doses: 3, 10, 30 and 60 μg/kg) was administered on days 1, 3, 6, 8 and 10. ARA290 exerted a dose-response effect by significantly reducing mechanical allodynia up to 20 weeks when compared to vehicle. The reduction of cold allodynia was significant up to 20 weeks for the doses 3, 10, 30 and 60 μg/kg when compared to vehicle. The effect 10 and 30 μg/kg ARA290 and vehicle on the microglia response (iba-1-immunoreactivity, iba-1-IR) and astrocyte reaction (GFAP-immunoreactivity, GFAP-IR) was investigated in animals surviving 2 (group 1) or 20 (group 2) weeks following lesion or sham surgery. In group 1, significant microglia reactivity was observed in the L5 segment of the spinal cord of animals treated with vehicle when compared to sham operated, while animals treated with 10 or 30 μg/kg did not show a increase. In group 2, a more widespread and increased microglia reactivity was observed for animals treated with 0 and 10 μg/kg when compared to sham operated animals, indicated by involvement of more spinal cord segments and higher iba-1-IR. Animals treated with 30 μg/kg did not show increased microglia reactivity. No difference in astrocyte reaction was observed.

Conclusions: The erythropoietin-analogue ARA290 dose-dependently reduced allodynia coupled to suppression of the spinal microglia response, suggestive of a mechanistic link between ARA290-induced suppression of central inflammation and relief of neuropathic pain symptoms.

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Effect of ARA 290 on Iba-1 immunoreactivity in the L5 spinal cord segment of animals 2 weeks after spared nerve injury. Representative photomicrographs of Iba-1 immunoreactivity (green) in the L5 spinal cord segment of animals 2 weeks after spared nerve injury (SNI). (A-C) Low power magnifications, (D-F) detailed images of (A-C) as indicated by the white rectangles, and (G-I) high power magnifications of the spinal cord of animals that underwent: A, D and G. SNI and vehicle treatment, B, E and H. SNI and treatment with 30 μg/kg ARA 290, C, F and I. sham surgery without treatment. The left-hand side of the photomicrographs represents the ipsilateral side of the animal, innervating the site of spared nerve injury.
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Figure 3: Effect of ARA 290 on Iba-1 immunoreactivity in the L5 spinal cord segment of animals 2 weeks after spared nerve injury. Representative photomicrographs of Iba-1 immunoreactivity (green) in the L5 spinal cord segment of animals 2 weeks after spared nerve injury (SNI). (A-C) Low power magnifications, (D-F) detailed images of (A-C) as indicated by the white rectangles, and (G-I) high power magnifications of the spinal cord of animals that underwent: A, D and G. SNI and vehicle treatment, B, E and H. SNI and treatment with 30 μg/kg ARA 290, C, F and I. sham surgery without treatment. The left-hand side of the photomicrographs represents the ipsilateral side of the animal, innervating the site of spared nerve injury.

Mentions: In Figure 3, representative overviews are given from the spinal cords of animals after 2 weeks of survival that received SNI with vehicle (Figure 3A), SNI with 30 μg/kg ARA 290 (Figure 3B) or sham surgery without treatment (Figure 3C). There was an apparent increased iba-1-immunoreactivity (iba-1-IR) on the side of the injury that seemed more pronounced in the 0 μg/kg treated group when compared to the 30 μg/kg group. The dorsal horns of animals that received SNI and treatment with vehicle (Figure 3D), 30 μg/kg ARA 290 (Figure 3E) or sham surgery without treatment (Figure 3F) showed increased iba-1-IR in the dorsal horn which was more pronounced in vehicle-treated animals. High power magnifications of individual microglia from the dorsal horns of animals that received SNI and treatment with vehicle (Figure 3G), 30 μg/kg ARA 290 (Figure 3H) or sham surgery without treatment (Figure 3I). Microglia from the vehicle-treated group showed an activated phenotype with an amoeboid shape and retracted rami, whereas microglia from the 30 μg/kg treatment group and sham surgery group showed a resting phenotype with a stretched soma and rami. For further analysis, computerized calculation of the amount of immunoreactivity was performed.


ARA 290, a peptide derived from the tertiary structure of erythropoietin, produces long-term relief of neuropathic pain coupled with suppression of the spinal microglia response.

Swartjes M, van Velzen M, Niesters M, Aarts L, Brines M, Dunne A, Cerami A, Dahan A - Mol Pain (2014)

Effect of ARA 290 on Iba-1 immunoreactivity in the L5 spinal cord segment of animals 2 weeks after spared nerve injury. Representative photomicrographs of Iba-1 immunoreactivity (green) in the L5 spinal cord segment of animals 2 weeks after spared nerve injury (SNI). (A-C) Low power magnifications, (D-F) detailed images of (A-C) as indicated by the white rectangles, and (G-I) high power magnifications of the spinal cord of animals that underwent: A, D and G. SNI and vehicle treatment, B, E and H. SNI and treatment with 30 μg/kg ARA 290, C, F and I. sham surgery without treatment. The left-hand side of the photomicrographs represents the ipsilateral side of the animal, innervating the site of spared nerve injury.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928087&req=5

Figure 3: Effect of ARA 290 on Iba-1 immunoreactivity in the L5 spinal cord segment of animals 2 weeks after spared nerve injury. Representative photomicrographs of Iba-1 immunoreactivity (green) in the L5 spinal cord segment of animals 2 weeks after spared nerve injury (SNI). (A-C) Low power magnifications, (D-F) detailed images of (A-C) as indicated by the white rectangles, and (G-I) high power magnifications of the spinal cord of animals that underwent: A, D and G. SNI and vehicle treatment, B, E and H. SNI and treatment with 30 μg/kg ARA 290, C, F and I. sham surgery without treatment. The left-hand side of the photomicrographs represents the ipsilateral side of the animal, innervating the site of spared nerve injury.
Mentions: In Figure 3, representative overviews are given from the spinal cords of animals after 2 weeks of survival that received SNI with vehicle (Figure 3A), SNI with 30 μg/kg ARA 290 (Figure 3B) or sham surgery without treatment (Figure 3C). There was an apparent increased iba-1-immunoreactivity (iba-1-IR) on the side of the injury that seemed more pronounced in the 0 μg/kg treated group when compared to the 30 μg/kg group. The dorsal horns of animals that received SNI and treatment with vehicle (Figure 3D), 30 μg/kg ARA 290 (Figure 3E) or sham surgery without treatment (Figure 3F) showed increased iba-1-IR in the dorsal horn which was more pronounced in vehicle-treated animals. High power magnifications of individual microglia from the dorsal horns of animals that received SNI and treatment with vehicle (Figure 3G), 30 μg/kg ARA 290 (Figure 3H) or sham surgery without treatment (Figure 3I). Microglia from the vehicle-treated group showed an activated phenotype with an amoeboid shape and retracted rami, whereas microglia from the 30 μg/kg treatment group and sham surgery group showed a resting phenotype with a stretched soma and rami. For further analysis, computerized calculation of the amount of immunoreactivity was performed.

Bottom Line: ARA290 exerted a dose-response effect by significantly reducing mechanical allodynia up to 20 weeks when compared to vehicle.The reduction of cold allodynia was significant up to 20 weeks for the doses 3, 10, 30 and 60 μg/kg when compared to vehicle.In group 1, significant microglia reactivity was observed in the L5 segment of the spinal cord of animals treated with vehicle when compared to sham operated, while animals treated with 10 or 30 μg/kg did not show a increase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesiology, Leiden University Medical Center, P5-Q, 2300 RC Leiden, The Netherlands. a.dahan@lumc.nl.

ABSTRACT

Background: Neuropathic pain is a difficult to treat disorder arising from central or peripheral nervous system lesions. The etiology of neuropathic pain consists of several overlapping pathways converging into an exaggerated pain state with symptoms such as allodynia and hyperalgesia. One of these pathways involves activation of spinal cord microglia and astrocytes, which drive and maintain the inflammatory response following the lesion. These cells are a potential target for drugs for neuropathic pain relief. In this current study, we investigated the dose-effect relationship of the tissue protective peptide ARA 290, derived from the tertiary structure of erythropoietin, on allodynia and concurrent spinal cord microglia and astrocytes.

Results: Following a spared nerve injury in rats, vehicle or ARA290 (administered in either one of 4 doses: 3, 10, 30 and 60 μg/kg) was administered on days 1, 3, 6, 8 and 10. ARA290 exerted a dose-response effect by significantly reducing mechanical allodynia up to 20 weeks when compared to vehicle. The reduction of cold allodynia was significant up to 20 weeks for the doses 3, 10, 30 and 60 μg/kg when compared to vehicle. The effect 10 and 30 μg/kg ARA290 and vehicle on the microglia response (iba-1-immunoreactivity, iba-1-IR) and astrocyte reaction (GFAP-immunoreactivity, GFAP-IR) was investigated in animals surviving 2 (group 1) or 20 (group 2) weeks following lesion or sham surgery. In group 1, significant microglia reactivity was observed in the L5 segment of the spinal cord of animals treated with vehicle when compared to sham operated, while animals treated with 10 or 30 μg/kg did not show a increase. In group 2, a more widespread and increased microglia reactivity was observed for animals treated with 0 and 10 μg/kg when compared to sham operated animals, indicated by involvement of more spinal cord segments and higher iba-1-IR. Animals treated with 30 μg/kg did not show increased microglia reactivity. No difference in astrocyte reaction was observed.

Conclusions: The erythropoietin-analogue ARA290 dose-dependently reduced allodynia coupled to suppression of the spinal microglia response, suggestive of a mechanistic link between ARA290-induced suppression of central inflammation and relief of neuropathic pain symptoms.

Show MeSH
Related in: MedlinePlus