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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 on L1-L6 spinal cord segments of animals 2 and 20 weeks after spared nerve injury. A. Representative photomicrographs of Iba-1 immunoreactivity (green) in the lumbar dorsal horns of animals 2 weeks after spared nerve injury (SNI). Animals were either treated with vehicle (upper row), 10 μg/kg ARA 290 (second row) or 30 μg/kg ARA 290 (third row). The bottom row represents sham-operated animals without treatment. In each column, the Iba-1 immunoreactivity signal at different lumbar spinal cord levels (L1-L6) is shown. Inserts show higher magnifications of the photomicrographs. B. Representative photomicrographs of Iba-1 immunoreactivity (green) in the lumbar dorsal horns of animals 20 weeks after spared nerve injury (SNI). Animals were either treated with vehicle (upper row), 10 μg/kg ARA 290 (second row) or 30 μg/kg ARA 290 (third row). The bottom row represents sham-operated animals without treatment. In each column, the Iba-1 immunoreactivity signal at different lumbar spinal cord levels (L1-L6) is shown. Inserts show higher magnifications of the photomicrographs.
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Figure 4: Effect of ARA 290 on Iba-1 immunoreactivity on L1-L6 spinal cord segments of animals 2 and 20 weeks after spared nerve injury. A. Representative photomicrographs of Iba-1 immunoreactivity (green) in the lumbar dorsal horns of animals 2 weeks after spared nerve injury (SNI). Animals were either treated with vehicle (upper row), 10 μg/kg ARA 290 (second row) or 30 μg/kg ARA 290 (third row). The bottom row represents sham-operated animals without treatment. In each column, the Iba-1 immunoreactivity signal at different lumbar spinal cord levels (L1-L6) is shown. Inserts show higher magnifications of the photomicrographs. B. Representative photomicrographs of Iba-1 immunoreactivity (green) in the lumbar dorsal horns of animals 20 weeks after spared nerve injury (SNI). Animals were either treated with vehicle (upper row), 10 μg/kg ARA 290 (second row) or 30 μg/kg ARA 290 (third row). The bottom row represents sham-operated animals without treatment. In each column, the Iba-1 immunoreactivity signal at different lumbar spinal cord levels (L1-L6) is shown. Inserts show higher magnifications of the photomicrographs.

Mentions: Representative images of recorded photomicrographs of iba-1-IR in lumbar dorsal horns L1 to L6 of animals at 2 weeks and 20 weeks following SNI surgery and treated with the various ARA 290 doses are given in Figure 4A and B with high power magnifications of microglia cells presented in the inserts. For group 1 (2 weeks post injury), microglia in the L5 segment of the vehicle treatment group showed an activated phenotype, whereas the microglia in other panels show a resting phenotype. Iba-1-IR was increased in the L5 segment following vehicle treatment only (Figure 5A, p < 0.05 versus sham). Irrespective of treatment, no increase in reactivity was observed in any of the other segments. In contrast, in group 2 (20 weeks post injury), iba-1-IR had spread both cranially and caudally to multiple spinal cord segments in vehicle-treated animals (Figure 4B) with significantly increased iba-1-IR in segments L2 to L5 (p < 0.05 vs. sham). As shown in the inserts of Figure 4B, microglia in the L1-L6 segments of the vehicle and 10 μg/kg treatment groups showed an activated phenotype, whereas the microglia in the 30 μg/kg and sham groups showed a resting phenotype. In Groups 1 and 2, treatment with 30 μg/kg ARA 290 prevented an increase in iba-1-IR as shown by the absence of iba-1-IR in all segments (Figure 5A and B; 30 μg/kg: ns vs. sham, p < 0.05 vs. vehicle at segments L2 to L4). In Group 2, treatment with 10 μg/kg of ARA 290 did not decrease iba-1-IR relative to vehicle-treated animals (Figure 5B; ns vs. vehicle, p < 0.05 vs. 30 μg/kg at segments L2-L4).


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 on L1-L6 spinal cord segments of animals 2 and 20 weeks after spared nerve injury. A. Representative photomicrographs of Iba-1 immunoreactivity (green) in the lumbar dorsal horns of animals 2 weeks after spared nerve injury (SNI). Animals were either treated with vehicle (upper row), 10 μg/kg ARA 290 (second row) or 30 μg/kg ARA 290 (third row). The bottom row represents sham-operated animals without treatment. In each column, the Iba-1 immunoreactivity signal at different lumbar spinal cord levels (L1-L6) is shown. Inserts show higher magnifications of the photomicrographs. B. Representative photomicrographs of Iba-1 immunoreactivity (green) in the lumbar dorsal horns of animals 20 weeks after spared nerve injury (SNI). Animals were either treated with vehicle (upper row), 10 μg/kg ARA 290 (second row) or 30 μg/kg ARA 290 (third row). The bottom row represents sham-operated animals without treatment. In each column, the Iba-1 immunoreactivity signal at different lumbar spinal cord levels (L1-L6) is shown. Inserts show higher magnifications of the photomicrographs.
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Figure 4: Effect of ARA 290 on Iba-1 immunoreactivity on L1-L6 spinal cord segments of animals 2 and 20 weeks after spared nerve injury. A. Representative photomicrographs of Iba-1 immunoreactivity (green) in the lumbar dorsal horns of animals 2 weeks after spared nerve injury (SNI). Animals were either treated with vehicle (upper row), 10 μg/kg ARA 290 (second row) or 30 μg/kg ARA 290 (third row). The bottom row represents sham-operated animals without treatment. In each column, the Iba-1 immunoreactivity signal at different lumbar spinal cord levels (L1-L6) is shown. Inserts show higher magnifications of the photomicrographs. B. Representative photomicrographs of Iba-1 immunoreactivity (green) in the lumbar dorsal horns of animals 20 weeks after spared nerve injury (SNI). Animals were either treated with vehicle (upper row), 10 μg/kg ARA 290 (second row) or 30 μg/kg ARA 290 (third row). The bottom row represents sham-operated animals without treatment. In each column, the Iba-1 immunoreactivity signal at different lumbar spinal cord levels (L1-L6) is shown. Inserts show higher magnifications of the photomicrographs.
Mentions: Representative images of recorded photomicrographs of iba-1-IR in lumbar dorsal horns L1 to L6 of animals at 2 weeks and 20 weeks following SNI surgery and treated with the various ARA 290 doses are given in Figure 4A and B with high power magnifications of microglia cells presented in the inserts. For group 1 (2 weeks post injury), microglia in the L5 segment of the vehicle treatment group showed an activated phenotype, whereas the microglia in other panels show a resting phenotype. Iba-1-IR was increased in the L5 segment following vehicle treatment only (Figure 5A, p < 0.05 versus sham). Irrespective of treatment, no increase in reactivity was observed in any of the other segments. In contrast, in group 2 (20 weeks post injury), iba-1-IR had spread both cranially and caudally to multiple spinal cord segments in vehicle-treated animals (Figure 4B) with significantly increased iba-1-IR in segments L2 to L5 (p < 0.05 vs. sham). As shown in the inserts of Figure 4B, microglia in the L1-L6 segments of the vehicle and 10 μg/kg treatment groups showed an activated phenotype, whereas the microglia in the 30 μg/kg and sham groups showed a resting phenotype. In Groups 1 and 2, treatment with 30 μg/kg ARA 290 prevented an increase in iba-1-IR as shown by the absence of iba-1-IR in all segments (Figure 5A and B; 30 μg/kg: ns vs. sham, p < 0.05 vs. vehicle at segments L2 to L4). In Group 2, treatment with 10 μg/kg of ARA 290 did not decrease iba-1-IR relative to vehicle-treated animals (Figure 5B; ns vs. vehicle, p < 0.05 vs. 30 μg/kg at segments L2-L4).

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