prostaglandin-d2 and Airway-Obstruction

Prostaglandin (PG)D2 is a major product of arachidonic acid metabolism in pulmonary mast cells. We therefore attempted to determine whether measurement of the stable urinary metabolite of PGD2, 9 alpha, 11 beta-PGF2, could serve as a marker of mast cell activation in the lungs. A commercially available enzyme immunoassay was validated and found to be specific and sensitive when applied to unpurified urine. There was no diurnal variation in the levels of 9 alpha, 11 beta-PGF2 in healthy volunteers. Morning baseline values of urinary 9 alpha, 11 beta-PGF2 were measured in three groups--healthy volunteers (n = 9), patients with atopic asthma (n = 14), and aspirin-intolerant patients with asthma (n = 12)--and found to be very similar, 54 +/- 9, 62 +/- 6, and 71 +/- 15 ng/mmol creatinine, respectively (means +/- SEM). Urinary excretion of 9 alpha, 11 beta-PGF2 was increased threefold immediately after allergen-induced bronchoconstriction in nine patients with atopic asthma. Bronchial challenge with inhaled lysine aspirin in eight aspirin-intolerant patients with asthma produced bronchoconstriction without extrapulmonary symptoms and was also followed by a significant increase in the urinary excretion of 9 alpha, 11 beta-PGF2. In addition, challenge with a higher dose of aspirin produced an even greater increase in urinary 9 alpha, 11 beta-PGF2, supporting dose-dependent release of PGD2 during aspirin-induced bronchoconstriction. In contrast, the postchallenge levels of urinary 9 alpha, 11 beta-PGF2 were not increased when bronchoconstriction was induced by histamine challenge in the aspirin-intolerant patients with asthma. The study confirms mast cell involvement in allergen-induced bronchoconstriction and provides novel data, which strongly support the hypothesis that pulmonary mast cells are activated during aspirin-induced airway obstruction. It is finally suggested that measurement of urinary 9 alpha, 11 beta-PGF2 with enzyme immunoassay may be used as a new noninvasive strategy to monitor mast cell activation in vivo.

Topics: Adult; Airway Obstruction; Allergens; Aspirin; Asthma; Bronchial Provocation Tests; Chromatography, High Pressure Liquid; Cross-Over Studies; Dinoprost; Double-Blind Method; Histamine; Humans; Immunoenzyme Techniques; Lysine; Mast Cells; Middle Aged; Prostaglandin D2

Asthma, a multifactorial, chronic inflammatory disease encompasses multiple complex pathways releasing number of mediators by activated mast cells, eosinophils and T lymphocytes, leading to its severity. Presently available medications are associated with certain limitations, and hence, it is imperative to search for anti-inflammatory drug preferably targeting signaling cascades involved in inflammation thereby suppressing inflammatory mediators without any side effect. Curcumin, an anti-inflammatory molecule with potent anti-asthmatic potential has been found to suppress asthmatic features by inhibiting airway inflammation and bronchoconstriction if administered through nasal route. The present study provides new insight towards anti-asthmatic potential of intranasal curcumin at lower doses (2.5 and 5.0 mg/kg) in Balb/c mice sensitized and challenged with ovalbumin (OVA) which is effective in inhibiting airway inflammation. These investigations suggest that intranasal curcumin (2.5 and 5.0 mg/kg) regulates airway inflammation and airway obstruction mainly by modulating cytokine levels (IL-4, 5, IFN-ƴ and TNF-α) and sPLA2 activity thereby inhibiting PGD2 release and COX-2 expression. Further, the suppression of p38 MAPK, ERK 42/44 and JNK54/56 activation elucidate the mechanism behind the inhibitory role of intranasal curcumin in asthma progression. Thus, curcumin could be better alternative for the development of nasal formulations and inhalers in near future.

Topics: Administration, Intranasal; Airway Obstruction; Animals; Asthma; Curcumin; Cytokines; Disease Models, Animal; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Humans; MAP Kinase Kinase 4; Mice; Mice, Inbred BALB C; p38 Mitogen-Activated Protein Kinases; Prostaglandin D2

Novel prostaglandin D(2) (PGD(2)) receptor antagonists were synthesized as a potential new class of antiallergic agents having a bicyclo[2.2.1]heptane ring system with sulfonamide groups. Some of them exhibit extremely potent antagonism of the PGD(2) receptor in radioligand binding and cAMP formation assays with IC(50) values below 50 nM and much less antagonism of TXA(2) and PGI(2) receptors. These potent PGD(2) receptor antagonists, when given orally, dramatically suppress various allergic inflammatory responses such as increased vascular permeability in allergic rhinitis, conjunctivitis, and asthma models. The excellent pharmacological profiles of PGD(2) receptor antagonists, originally synthesized in our laboratories, are of potentially great clinical significance. This study also provides experimental evidence suggesting that PGD(2) plays an important role in the pathogenesis of allergic diseases.

Topics: Administration, Oral; Airway Obstruction; Animals; Anti-Allergic Agents; Blood Platelets; Bridged Bicyclo Compounds; Capillary Permeability; Conjunctiva; Cyclic AMP; Guinea Pigs; Hexanes; Humans; In Vitro Techniques; Prostaglandin D2; Radioligand Assay; Receptors, Epoprostenol; Receptors, Immunologic; Receptors, Prostaglandin; Receptors, Thromboxane; Stereoisomerism; Structure-Activity Relationship; Sulfonamides

In an earlier paper, we reported that novel prostaglandin D(2) (PGD(2)) receptor antagonists having the bicyclo[2.2.1]heptane ring system as a prostaglandin skeleton were a potent new class of antiallergic agents and suppressed various allergic inflammatory responses such as those observed in conjunctivitis and asthma models. In the present study, we synthesized PGD(2) receptor antagonists having the 6,6-dimethylbicyclo[3.1.1]heptane ring system. These derivatives have the amide moiety, in contrast to those with the bicyclo[2.2.1]heptane ring system, which have the sulfonamide group. The derivatives having the 6,6-dimethylbicyclo[3.1.1]heptane ring also exhibited strong activity in PGD(2) receptor binding and cAMP formation assays. In in vivo assays such as allergic rhinitis, conjunctivitis, and asthma models, these series of derivatives showed excellent pharmacological profiles. In particular, compound 45 also effectively suppressed eosinophil infiltration in allergic rhinitis and asthma models. This compound (45, S-5751) is now being developed as a promising alternative antiallergic drug candidate.

Topics: Administration, Oral; Airway Obstruction; Animals; Anti-Allergic Agents; Asthma; Blood Platelets; Bridged Bicyclo Compounds; Capillary Permeability; Conjunctiva; Cyclic AMP; Eosinophils; Guinea Pigs; Heptanes; Humans; Prostaglandin D2; Radioligand Assay; Receptors, Immunologic; Receptors, Prostaglandin; Rhinitis, Allergic, Perennial; Stereoisomerism; Structure-Activity Relationship; Thiophenes

Although prostaglandin D2 (PGD2), a mast cell-derived inflammatory mediator, may trigger allergic airway inflammation, its potency and the mechanism by which it induces airway microvascular leakage, a component of airway inflammation, is not clear.. We wanted to evaluate the relative potency of PGD2 to cause microvascular leakage as compared to airflow obstruction, because both responses were shown to occur simultaneously in allergic airway diseases such as asthma. The role of thromboxane A2 receptors (TP receptors) in inducing these airway responses was also examined.. Anesthetized and mechanically ventilated guinea pigs were given i.v. Evans blue dye (EB dye) and, 1 min later, PGD2 (30, 100, 300 or 1,000 nmol/kg). For comparison, the effect of 150 nmol/kg histamine or 2 nmol/kg leukotriene D4 (LTD4) was also examined. Lung resistance (R(L)) was measured for 6 min (or 25 min for selected animals) and the lungs were removed to calculate the amount of extravasated EB dye into the airways as a marker of leakage. In some of the animals, specific TP receptor antagonists, S-1452 (10 microg/kg) or ONO-3708 (10 mg/kg), or a thromboxane A2 synthase inhibitor, OKY-046 (30 mg/kg), was pretreated before giving PGD2.. Injection of PGD2 produced an immediate and dose-dependent increase in RL (peaking within 1 min), which was significant at all doses studied. At 1,000 nmol/kg, PGD2 induced a later increase in R(L), starting at 3 min and reaching a second peak at 8 min. By contrast, only PGD2 at doses of 300 and 1,000 nmol/kg produced a significant increase in EB dye extravasation. The relative potency of 1,000 nmol/kg PGD2 to induce leakage as compared to airflow obstruction was comparable to histamine at most of airway levels, but less than LTD4. Both responses caused by PGD2 were completely abolished by S-1452 and ONO-3708, but not by OKY-046.. PGD2 may induce airway microvascular leakage by directly stimulating TP receptors without generating TXA2 in guinea pigs. Microvascular leakage may play a role in the development of allergic airway inflammation caused by PGD2.

Topics: Airway Obstruction; Animals; Blood Pressure; Capillaries; Capillary Permeability; Dose-Response Relationship, Drug; Evans Blue; Guinea Pigs; Histamine; Leukotriene D4; Lung; Prostaglandin D2; Receptors, Thromboxane; Thromboxane-A Synthase; Time Factors

Prostaglandin D2 (PGD2) was infused intravenously into normal male volunteers. Seven subjects received infusions of 16, 32, 64 ng/kg/min and six of these a further dose of 128 ng/kg/min. Each individual's maximum dose was limited by discomfort caused by intense facial flushing and nasal congestion. At these doses there was no significant effect on systolic or diastolic blood pressure nor on spirometric measurements. There was a small but statistically significant tachycardia at 64 and 128 ng/kg/min. Collagen- and adenosine diphosphate (ADP)-induced platelet aggregation ex vivo was not affected at any of the infusion rates. Infused PGD2 is unlikely to be a useful antithrombotic agent.

Topics: Adenosine Diphosphate; Adult; Airway Obstruction; Blood Pressure; Collagen; Flushing; Heart Rate; Humans; Infusions, Parenteral; Male; Platelet Aggregation; Prostaglandin D2; Prostaglandins D; Tachycardia