Effect of endotoxin treatment on the expression and localization of spinal cyclooxygenase, prostaglandin synthases, and PGD₂receptors

Abstract

Systemic inflammation leads to increased expression of spinal cyclooxygenase (COX)‐2 and to a subsequent increase of prostaglandin (PG) biosynthesis, which contribute to the development of hyperalgesia and allodynia. In this study, endotoxin caused a sequential induction of membrane bound prostaglandin E synthase‐1 and lipocalin‐type PGD synthase (L‐PGDS) in the mouse spinal cord. L‐PGDS expression was detected in the leptomeninges, oligodendrocytes, and interestingly, in discrete perivascular cells. Endotoxin‐caused increase was most prominent in oligodendrocytes. Endotoxin‐induced COX‐2 and membrane bound prostaglandin E synthase‐1 were restricted to the leptomeninges and perivascular cells. COX‐1 was not influenced by endotoxin. We found COX‐1 expressed in microglia, some of them in close proximity to L‐PGDS‐positive oligodendrocytes and co‐localization of COX‐1 with L‐PGDS in perivascular and leptomeningeal cells under control conditions. It can be assumed, that PGD2 biosynthesis under control conditions is mediated via COX‐1 and that during inflammation, increased PGD2 is dependent on COX‐2. We found the PGD2 receptors DP1 and chemoattractant receptor homologous molecule expressed on T helper type 2 cells (CRTH2) localized in neurons of the dorsal, and motoneurons in the ventral horn. The localization of the PGD2 receptors DP1 and CRTH in spinal cord neurons, particularly in neurons of lamina I and II involved in the processing of nociceptive stimuli, supports a role of PGD2 under inflammatory conditions.

Neuronal prostaglandin E 2 receptor subtype EP3 mediates antinociception during inflammation

“…Currently mainly cyclooxygenase inhibitors are used to treat musculoskeletal pain. However, general inhibition of prostaglandin synthesis may also reduce beneficial prostaglandin effects such as for prostaglandin D 2 (PGD 2 ), which is anti-inflammatory (31), antinociceptive under inflammatory conditions (32), and/or neuroprotective (33). Selective activation of EP3 receptors may be an alternative, in particular because this pain inhibitory mechanism is only functional under pathophysiological conditions such as inflammation.…”

Putative Role of Prostaglandin Receptor in Intracerebral Hemorrhage

“…Despite its expression in the spinal cord and its anti-inflammatory effect as an activator of peroxisome proliferator-activated receptors, little is known about the role of DP2 receptors after stroke (Genovese et al, 2008; Grill et al, 2008; Morgenweck et al, 2010). Based on the role of the DP2 receptor in cAMP inhibition and Ca 2+ activation, we hypothesize that activation of this receptor could lead to aggravated brain damage and its inhibition could lead to better functional and anatomical outcomes after ICH.…”

Interaction of eosinophils with endothelial cells is modulated by prostaglandin EP4 receptors

“…Purified eosinophils were treated with vehicle or 30 nM ONO AE1-329 for 10 min, activated with vehicle, eotaxin (3 nM), or PGD 2 (30 nM) for 12 min at 371C in the presence of mAb 24 (1:50) or isotype control Ab followed by staining with Alexa Fluor 488-labeled secondary Ab (1:500). The stained samples were either directly measured by flow cytometry [59] or were cytospun onto microscope slides (600 rpm 3 min, Cytospin3, Shandon) and observed with a Olympus IX70 fluorescence microscope and UPlanFI -60 Â /1.20 lens; images were acquired using a Hamamatsu ORCA-ER digital camera [60].…”

“…Purified eosinophils were treated with vehicle or 30 nM ONO AE1-329 for 10 min, activated with vehicle, eotaxin (3 nM), or PGD 2 (30 nM) for 12 min at 371C in the presence of mAb 24 (1:50) or isotype control Ab followed by staining with Alexa Fluor 488-labeled secondary Ab (1:500). The stained samples were either directly measured by flow cytometry [59] or were cytospun onto microscope slides (600 rpm 3 min, Cytospin3, Shandon) and observed with a Olympus IX70 fluorescence microscope and UPlanFI -60 Â /1.20 lens; images were acquired using a Hamamatsu ORCA-ER digital camera [60].Immunofluorescence staining of EP4 receptor on eosinophils EP4 expression of purified human eosinophils was detected by immunofluorescence and laser-scanning microscopy. The monoclonal mouse Ab used targets the C-terminal intracellular tail of the EP4 receptor, and thus the cells were fixed and permeabilized, and nonspecific binding sites were blocked with Ultra V Blocking solution for 30 min at room temperature.…”