Histamine and tryptase modulate asthmatic airway smooth muscle GM-CSF and RANTES release

Degranulating mast cells are increased in the airway smooth muscle (ASM) of asthmatics, where they may influence ASM function. The aim of the present study was to determine whether histamine and tryptase modulate ASM cell granulocyte-macrophage colony-stimulating factor (GM-CSF) and RANTES (regulated on activation, normal T-cell expressed and secreted) release and also to examine which receptors are involved in this release. Confluent, quiescent ASM cells from asthmatic and nonasthmatic donors were treated with histamine (1 microM-100 microM) with and without histamine receptor antagonist pre-treatment, or the protease-activated receptor (PAR)-2 agonists tryptase (0.5-5 nM) and SLIGKV (100 and 400 microM). The cells were then stimulated with interleukin (IL)-1beta and/or tumour necrosis factor (TNF)-alpha (10 ng.mL(-1)) or left unstimulated for 24 h. Release of GM-CSF and RANTES was determined by ELISA and prostaglandin (PG)E(2) measured by enzyme immunoassay. Neither histamine nor tryptase induced ASM GM-CSF or RANTES secretion. However, histamine increased IL-1beta-induced GM-CSF release and markedly reduced TNF-alpha-induced RANTES release by both asthmatic and nonasthmatic cells to a similar extent, but did not modulate PGE(2) release. All changes involved activation of the histamine H1 receptor as they were partially or fully blocked by chlorpheniramine, but not ranitidine. Tryptase, via its proteolytic activity, also potentiated GM-CSF, but not RANTES, release from asthmatic and nonasthmatic ASM cells induced by both cytokines. PAR-2 involvement in the tryptase potentiation was unlikely because SLIGKV had no effect. In conclusion, mast cells, through histamine and tryptase, may locally modulate airway smooth muscle-induced inflammation in asthma.

Mechanisms of serum potentiation of GM-CSF production by human airway smooth muscle cells

Inflammation and vascular leakage are prevalent in asthma. This study aimed to elucidate the mechanisms involved in serum potentiation of cytokine-induced granulocyte macrophage colony stimulating factor (GM-CSF) production by human airway smooth muscle cells and to identify possible factors responsible. Serum-deprived cells at low density were stimulated with TNF-alpha and IL-1beta for 24 h. Human AB serum (10%), inhibitors of RNA and protein synthesis or specific signaling molecules, or known smooth muscle mitogens were then added for 24 h. Culture supernatants were analyzed for GM-CSF levels, and cells were harvested to assess viability, cell cycle progression, GM-CSF-specific mRNA content, and p38 phosphorylation. Serum potentiated GM-CSF release when added before, together with (maximal), or after the cytokines. The potentiation involved both new GM-CSF-specific mRNA production and protein synthesis. The mitogens IGF, PDGF, and thrombin all potentiated GM-CSF release, and neutralizing antibodies for EGF, IGF, and PDGF reduced the serum potentiation. Inhibitor studies ruled as unlikely the involvement of p70(S6kinase) and the MAPK p42/p44, two signaling pathways implicated in proliferation, and the involvement of the MAPK JNK, while establishing roles for p38 MAPK and NF-kappaB in the potentiation of GM-CSF release. Detection of significant p38 phosphorylation in response to serum stimulation, through Western blotting, further demonstrated the involvement of p38. These studies have provided evidence to support p38 being targeted to interrupt the cycle of inflammation, vascular leakage and cytokine production in asthma.

Prediction of ifosfamide/mesna associated encephalopathy

Ifosfamide and mesna were administered to 77 patients with advanced malignancies. Seven (9%) experienced a severe but reversible encephalopathy. In 56% of patients in whom EEG data was available, characteristic changes were seen with or without mild clinical toxicity. Discriminant analysis identified low serum albumin concentration, high serum creatinine concentration and the presence of pelvic disease as variables which predispose patients to the development of severe encephalopathy. A nomogram has been constructed which can be used to determine the probability that an individual patient may be given ifosfamide and mesna safely. This has important implications for the clinical use of a highly active chemotherapy regimen.

Distribution of fibronectin in the rectal mucosa

Fibronectin is a glycoprotein of high molecular weight present in tissues, plasma, and tissue fluids. Its distribution in the rectal mucosa was studied by immunofluorescent and immunoperoxidase techniques using a monospecific antiserum. Immunofluorescent reactivity for fibronectin was present in the normal rectal mucosa of control subjects in epithelial cells, on basement membranes, and as a loose cribriform network of extracellular reactivity in the lamina propria that codistributed with histochemically demonstrable reticulin. Fibronectin was demonstrated immunoelectromicroscopically on collagen fibres, on smooth muscle cells and within and between columnar epithelial cells. In the rectal mucosa of patients with colitis with marked inflammatory changes, fibronectin appeared thickened and more prominent when present on basement membranes and as sparse strands between inflammatory cells infiltrating the lamina propria. In patients with longstanding colitis and less inflammatory cell infiltration there was a diffuse increase in fibronectin which was densely and uniformly present throughout the lamina propria. Fibronectin is a structural component of the rectal mucosa and changes in its distribution may form an important part of the local reaction to inflammatory bowel disease.