oxadiazoles and Hypersensitivity

In the present article synthesis and medicinal applications of [1, 2, 4] oxadiazoles are reviewed. The oxadiazoles have a wide range of applications such as Antitussive, Anti-inflammatory, Anaesthetic, Vasodilator, anthelmintic, antiallergic, antiplatelet effects in vitro, antithrombotic properties in vivo, etc. Many researchers have synthesized novel heterocyclic compounds containing oxadiazoles with the concept of bioisosterism.

Topics: Anesthetics; Animals; Anti-Inflammatory Agents; Antineoplastic Agents; Apoptosis; Blood Platelets; Fibrinolytic Agents; Hypersensitivity; Oxadiazoles; Platelet Aggregation Inhibitors; Vasodilator Agents; Venous Thrombosis

Soluble guanylyl cyclase (sGC) is an enzyme highly expressed in the lung that generates cGMP contributing to airway smooth muscle relaxation. To determine whether the bronchoconstriction observed in asthma is accompanied by changes in sGC expression, we used a well-established murine model of allergic asthma. Histological and biochemical analyses confirmed the presence of inflammation in the lungs of mice sensitized and challenged with ovalbumin (OVA). Moreover, mice sensitized and challenged with OVA exhibited airway hyperreactivity to methacholine inhalation. Steady-state mRNA levels for all sGC subunits (alpha1, alpha2, and beta1) were reduced in the lungs of mice with allergic asthma by 60-80%, as estimated by real-time PCR. These changes in mRNA were paralleled by changes at the protein level: alpha1, alpha2, and beta1 expression was reduced by 50-80% as determined by Western blotting. Reduced alpha1 and beta1 expression in bronchial smooth muscle cells was demonstrated by immunohistochemistry. To study if sGC inhibition mimics the airway hyperreactivity seen in asthma, we treated naïve mice with a selective sGC inhibitor. Indeed, in mice receiving ODQ the methacholine dose response was shifted to the left. We conclude that sGC expression is reduced in experimental asthma contributing to the observed airway hyperreactivity.

Topics: Animals; Asthma; Bronchial Hyperreactivity; Bronchoconstrictor Agents; Enzyme Inhibitors; Guanylate Cyclase; Homeostasis; Hypersensitivity; Isoenzymes; Methacholine Chloride; Mice; Ovalbumin; Oxadiazoles; Quinoxalines; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Soluble Guanylyl Cyclase

Because interferon-gamma, interleukin-4, and interleukin-5 have been identified at the mRNA and protein levels in the lesional skin of patients with atopic dermatitis, we investigated the roles played by granulocytes as effector cells in allergic inflammation by using two unique murine skin models. In vitro generated Th1 and Th2 cells from naïve splenocytes of antiovalbumin T cell receptor transgenic BALB/C mice were adoptively transferred with ovalbumin into the ear pinnae or air-pouches produced in the back skin of naïve, nontransgenic BALB/C mice. The injection of Th1 cells with ovalbumin induced delayed type ear swelling that peaked at 48 h, whereas that of Th2 resulted in ear swelling that peaked at a much earlier time, 24 h. Histologic study of the swollen ear skin and granulocytes recruited into the air-pouch demonstrated that, although the Th1-induced inflammation caused a neutrophil-predominant infiltrate with few eosinophils, larger numbers of eosinophils accumulated in the Th2-induced inflammation. Using these murine models, we further evaluated the effects of drugs used for the treatment of atopic diseases. The results showed that FK506 administration could effectively reduce skin inflammation induced by either Th cells. Interestingly, the neutrophil elastase inhibitor ONO-6818 efficiently inhibited Th1-induced inflammation. In contrast, a leukotriene receptor antagonist, ONO-1078, specifically suppressed Th2-induced inflammation. We also found that each ONO drug exerted direct influence on specified granulocytes, as neither affected in vitro production of relevant Th cytokines. Thus, we succeeded in developing animal skin inflammation models in which we can evaluate the contribution of protein antigen-specific Th1 or Th2 cells through the action of granulocytic effector cells.

Topics: Animals; Cells, Cultured; Chromones; Dermatitis, Atopic; Disease Models, Animal; Ear; Edema; Enzyme Inhibitors; Eosinophils; Hypersensitivity; Immunosuppressive Agents; Leukotriene Antagonists; Male; Mice; Mice, Inbred BALB C; Neutrophils; Ovalbumin; Oxadiazoles; Pyrimidinones; Skin; Tacrolimus; Th1 Cells; Th2 Cells

In humans intimal thickening is aprerequisite of atherosclerosis. Application of a silicone collar around the rabbit carotid artery induces an intimal thickening but in addition it increases the sensitivity to the vasoconstrictor action of serotonin (5-hydroxytryptamine, 5-HT). The 5-HT receptors involved in collar-induced hypersensitivity to 5-HT were investigated using several agonists and antagonists. One week after placement of collars around both carotid arteries of anaesthetized rabbits, rings (2 mm width) from inside (=collar) and outside (=sham) the collars were mounted in organ baths (10 ml) for isometric force measurements at 6 g loading tension. Collared rings were more sensitive to the contractile effect of 5-HT (7.6 fold) and 5-carboxamidotryptamine (31 fold, 5-CT, 5-HT1 agonist) in cumulative concentration response curves. Sumatriptan (5-HT1B/1D agonist) caused concentration-dependent constrictions in collared rings only. Collar placement did not significantly alter pA2 values (Schild regression) or apparent pKb values (non-linear regression) of spiperone and methysergide (mixed 5-HT2A/5-HT1 antagonists) or ketanserin and ritanserin (5-HT2A antagonists), indicating unchanged binding characteristics of the 5-HT2A receptor. However, the reduced slope of the Schild regression pointed to a heterogeneous receptor population in collared rings. In contrast, the apparent pKb value of methiothepin (5-HT1B antagonist) was significantly reduced by collar placement, and its antagonism shifted from non-surmountable in sham rings to surmountable in collared segments. Taken together, this study demonstrates that the serotonergic receptor involved in the hypersensitivity to 5-HT of rabbit collared carotid artery is a 5-HT1B receptor subtype.

Topics: 8-Hydroxy-2-(di-n-propylamino)tetralin; Animals; Braces; Carotid Arteries; Dose-Response Relationship, Drug; Hypersensitivity; In Vitro Techniques; Ketanserin; Male; Methysergide; Oxadiazoles; Piperazines; Potassium Chloride; Rabbits; Receptor, Serotonin, 5-HT1B; Receptor, Serotonin, 5-HT2A; Receptors, Serotonin; Ritanserin; Serotonin; Serotonin Antagonists; Serotonin Receptor Agonists; Spiperone; Sumatriptan; Tryptamines; Vasoconstriction