Disodium cromoglycate stabilizes mast cell degranulation while reducing the number of hemoglobin-induced microvascular leaks in rat mesentery

Mast cells can contribute to axon-glial dissociation and fibrosis in peripheral nerve

Expression of the human epidermal growth factor receptor (EGFR) in murine Schwann cells results in loss of axon-Schwann cell interactions and collagen deposition, modeling peripheral nerve response to injury and tumorigenesis. Mast cells infiltrate nerves in all three situations. We show that mast cells are present in normal mouse peripheral nerve beginning at 4 weeks of age, and that the number of mast-cells in EGFR(+) nerves increases abruptly at 5-6 weeks of age as axons and Schwann cells dissociate. The increase in mast cell number is preceded and accompanied by elevated levels of mRNAs encoding the mast-cell chemoattractants Rantes, SCF and VEGF. Genetic ablation of mast cells and bone marrow reconstitution in W(41) x EGFR(+) mice indicate a role for mast cells in loss of axon-Schwann cell interactions and collagen deposition. Pharmacological stabilization of mast cells by disodium cromoglycate administration to EGFR(+) mice also diminished loss of axon-Schwann cell interaction. Together these three lines of evidence support the hypothesis that mast cells can contribute to alterations in peripheral nerves.

A crucial role for TNF-alpha in mediating neutrophil influx induced by endogenously generated or exogenous chemokines, KC/CXCL1 and LIX/CXCL5

BACKGROUND AND PURPOSE

Chemokines orchestrate neutrophil recruitment to inflammatory foci. In the present study, we evaluated the participation of three chemokines, KC/CXCL1, MIP-2/CXCL2 and LIX/CXCL5, which are ligands for chemokine receptor 2 (CXCR2), in mediating neutrophil recruitment in immune inflammation induced by antigen in immunized mice.

EXPERIMENTAL APPROACH

Neutrophil recruitment was assessed in immunized mice challenged with methylated bovine serum albumin, KC/CXCL1, LIX/CXCL5 or tumour necrosis factor (TNF)-alpha. Cytokine and chemokine levels were determined in peritoneal exudates and in supernatants of macrophages and mast cells by elisa. CXCR2 and intercellular adhesion molecule 1 (ICAM-1) expression was determined using immunohistochemistry and confocal microscopy.

KEY RESULTS

Antigen challenge induced dose- and time-dependent neutrophil recruitment and production of KC/CXCL1, LIX/CXCL5 and TNF-alpha, but not MIP-2/CXCL2, in peritoneal exudates. Neutrophil recruitment was inhibited by treatment with reparixin (CXCR1/2 antagonist), anti-KC/CXCL1, anti-LIX/CXCL5 or anti-TNF-alpha antibodies and in tumour necrosis factor receptor 1-deficient mice. Intraperitoneal injection of KC/CXCL1 and LIX/CXCL5 induced dose- and time-dependent neutrophil recruitment and TNF-alpha production, which were inhibited by reparixin or anti-TNF-alpha treatment. Macrophages and mast cells expressed CXCR2 receptors. Increased macrophage numbers enhanced, while cromolyn sodium (mast cell stabilizer) diminished, LIX/CXCL5-induced neutrophil recruitment. Macrophages and mast cells from immunized mice produced TNF-alpha upon LIX/CXCL5 stimulation. Methylated bovine serum albumin induced expression of ICAM-1 on mesenteric vascular endothelium, which was inhibited by anti-TNF-alpha or anti-LIX/CXCL5.

CONCLUSION AND IMPLICATIONS

Following antigen challenge, CXCR2 ligands are produced and act on macrophages and mast cells triggering the production of TNF-alpha, which synergistically contribute to neutrophil recruitment through induction of the expression of ICAM-1.

Sodium cromoglycate inhibits absorption of the major soybean allergen, Gly m Bd 30K, in mice and human intestinal Caco-2 cells

Our previous data showed that Gly m Bd 30K was absorbed from the gastrointestinal tract and circulated in blood in mice. This study was conducted to determine the mechanism and identify the inhibitor of such absorption. Using sandwich ELISA and immunoblotting, we found that intact Gly m Bd 30K was absorbed from apical to basolateral solutions and intracellularly accumulated by Caco-2 cells in a dose- and time-dependent manner. The absorption and intracellular accumulation of Gly m Bd 30K were significantly suppressed when Caco-2 cells were treated with sodium cromoglycate (SCG) (0-50 mmol/L) in a dose-dependent manner. In 24-d-old mice orally treated with SCG (10-1000 mg/kg body weight), plasma Gly m Bd 30K concentration decreased significantly 30-120 min after Gly m Bd 30K (2000 mg/kg body weight) administration. Moreover, inhibitors that suppress the clathrin-dependent endocytosis dansylcadaverine, the caveolae-dependent endocytosis nystatin and clathrin, and the caveolae-dependent endocytosis methyl-beta-cyclodextrin had inhibitory effects on the absorption and intracellular accumulation of Gly m Bd 30K by Caco-2 cells. These data indicate that Gly m Bd 30K is absorbed and intracellularly accumulated in Caco-2 cells via clathrin- or caveolae-dependent endocytosis. We propose that the absorption and intracellular accumulation of Gly m Bd 30K are inhibited by SCG via clathrin- or caveolae-dependent endocytosis.