Different phosphoinositide 3-kinase isoforms mediate carrageenan nociception and inflammation

作者：Pritchard Rory A; Falk Lovissa; Larsson Mathilda; Leinders Mathias; Sorkin Linda S^*

来源：Pain, 2016, 157(1): 137-146.

DOI：10.1097/j.pain.0000000000000341

• c-Fos
• Edema
• Macrophage
• Neutrophil
• Plasma extravasation
• Pain

Phosphoinositide 3-kinases (PI3Ks) participate in signal transduction cascades that can directly activate and sensitize nociceptors and enhance pain transmission. They also play essential roles in chemotaxis and immune cell infiltration leading to inflammation. We wished to determine which PI3K isoforms were involved in each of these processes. Lightly anesthetized rats (isoflurane) were injected subcutaneously with carrageenan in their hind paws. This was preceded by a local injection of 1% DMSO vehicle or an isoform-specific antagonist to PI3K-alpha (compound 15-e), -beta (TGX221), -delta (Cal-101), or -gamma (AS252424). We measured changes in the mechanical pain threshold and spinal c-Fos expression (4 hours after injection) as indices of nociception. Paw volume, plasma extravasation (Evans blue, 0.3 hours after injection), and neutrophil (myeloperoxidase; 1 hour after injection) and macrophage (CD11b+; 4 hour after injection) infiltration into paw tissue were the measured inflammation endpoints. Only PI3K-gamma antagonist before treatment reduced the carrageenan-induced pain behavior and spinal expression of c-Fos (P <= 0.01). In contrast, pretreatment with PI3K-alpha, -delta, and-gamma antagonists reduced early indices of inflammation. Plasma extravasation PI3K-alpha (P <= 0.05), -delta (P <= 0.05), and -gamma (P <= 0.01), early (0-2 hour) edema -alpha (P <= 0.05), -delta (P <= 0.001), and -gamma (P <= 0.05), and neutrophil infiltration (all P <= 0.001) were all reduced compared to vehicle pretreatment. Later (2-4 hour), edema and macrophage infiltration (P <= 0.05) were reduced by only the PI3K-delta and -gamma isoform antagonists, with the PI3K-delta antagonist having a greater effect on edema. PI3K-beta antagonism was ineffective in all paradigms. These data indicate that pain and clinical inflammation are pharmacologically separable and may help to explain clinical conditions in which inflammation naturally wanes or goes into remission, but pain continues unabated.

• 出版日期2016-1