Mast Cell Degranulation and Fibroblast Activation in the Morphine-induced Spinal Mass: Role of Mas-related G Protein-coupled Receptor Signaling.

BACKGROUND: As the meningeally derived, fibroblast-rich, mass-produced by intrathecal morphine infusion is not produced by all opiates, but reduced by mast cell stabilizers, the authors hypothesized a role for meningeal mast cell/fibroblast activation. Using the guinea pig, the authors asked: (1) Are intrathecal morphine masses blocked by opiate antagonism?; (2) Do opioid agonists not producing mast cell degranulation or fibroblast activation produce masses?; and (3) Do masses covary with Mas-related G protein-coupled receptor signaling thought to mediate mast cell degranulation? METHODS: In adult male guinea pigs (N = 66), lumbar intrathecal catheters connected to osmotic minipumps (14 days; 0.5 µl/h) were placed to deliver saline or equianalgesic concentrations of morphine sulfate (33 nmol/h), 2',6'-dimethyl tyrosine-(Tyr-D-Arg-Phe-Lys-NH2) (abbreviated as DMT-DALDA; 10 pmol/h; µ agonist) or PZM21 (27 nmol/h; biased µ agonist). A second pump delivered subcutaneous naltrexone (25 µg/h) in some animals. After 14 to 16 days, animals were anesthetized and perfusion-fixed. Drug effects on degranulation of human cultured mast cells, mouse embryonic fibroblast activation/migration/collagen formation, and Mas-related G protein-coupled receptor activation (PRESTO-Tango assays) were determined. RESULTS: Intrathecal infusion of morphine, DMT-DALDA or PZM21, but not saline, comparably increased thermal thresholds for 7 days. Spinal masses proximal to catheter tip, composed of fibroblast/collagen type I (median: interquartile range, 0 to 4 scale), were produced by morphine (2.3: 2.0 to 3.5) and morphine plus naltrexone (2.5: 1.4 to 3.1), but not vehicle (1.2: 1.1 to 1.5), DMT-DALDA (1.0: 0.6 to 1.3), or PZM21 (0.5: 0.4 to 0.8). Morphine in a naloxone-insensitive fashion, but not PZM21 or DMT-DALDA, resulted in mast cell degranulation and fibroblast proliferation/collagen formation. Morphine-induced fibroblast proliferation, as mast cell degranulation, is blocked by cromolyn. Mas-related G protein-coupled receptor activation was produced by morphine and TAN67 (∂-opioid agonist), but not by PZM21, TRV130 (mu biased ligand), or DMT-DALDA. CONCLUSIONS: Opiates that activate Mas-related G protein-coupled receptor will degranulate mast cells, activate fibroblasts, and result in intrathecal mass formation. Results suggest a mechanistically rational path forward to safer intrathecal opioid therapeutics.

Colorectal metastasis to the gallbladder mimicking a primary gallbladder malignancy: histopathological and molecular characteristics.

AIMS: Outcomes of colorectal cancer (CRC) treatment and survival have steadily improved during the past decades, accompanied by an increased risk of developing second primary tumours and metastatic tumours at unusual sites. Metastatic CRC can show mucosal colonisation, thereby mimicking a second primary tumour. This potential confusion could lead to incorrect diagnosis and consequently inadequate treatment of the patient. The aim of this study was to differentiate between metastatic CRC and a second primary (gallbladder cancer, GBC) using a combination of standard histopathology and molecular techniques. METHODS AND RESULTS: Ten consecutive patients with both CRC and GBC were identified in our region using the Dutch National Pathology Archive (PALGA). Two patients served as negative controls. Histology of GBC was reviewed by nine pathologists. A combination of immunohistochemistry, microsatellite analysis, genomewide DNA copy number analysis and targeted somatic mutation analysis was used to aid in differential diagnosis. In two patients, CRC and GBC were clonally related, as confirmed by somatic mutation analysis. For one case, this was confirmed by genomewide DNA copy number analysis. However, in both cases, pathologists initially considered the GBC as a second primary tumour. CONCLUSIONS: Metastatic CRC displaying mucosal colonisation is often misinterpreted as a second primary tumour. A combination of traditional histopathology and molecular techniques improves this interpretation, and lowers the risk of inadequate treatment.