Cysteinyl leukotriene (cysLT) overproduction is a hallmark of aspirin-exacerbated respiratory disease (AERD), but its mechanism is poorly understood. Because adherent platelets can convert the leukocytederived precursor leukotriene (LT)A 4 to LTC 4 , the parent cysLT, through the terminal enzyme LTC 4 synthase, we investigated the contribution of platelet-dependent transcellular cysLT production in AERD. Nasal polyps from subjects with AERD contained many extravascular platelets that colocalized with leukocytes, and the percentages of circulating neutrophils, eosinophils, and monocytes with adherent platelets were markedly higher in the blood of subjects with AERD than in aspirintolerant controls. Platelet-adherent subsets of leukocytes had higher expression of several adhesion markers than did platelet nonadherent subsets. Adherent platelets contributed more than half of the total LTC 4 synthase activity of peripheral blood granulocytes, and they accounted for the higher level of LTC 4 generation by activated granulocytes from subjects with AERD compared with aspirintolerant controls. Urinary LTE 4 levels, a measure of systemic cysLT production, correlated strongly with percentages of circulating platelet-adherent granulocytes. Because platelet adherence to leukocytes allows for both firm adhesion to endothelial cells and augmented transcellular conversion of leukotrienes, a disturbance in plateletleukocyte interactions may be partly responsible for the respiratory tissue inflammation and the overproduction of cysLTs that characterize AERD. (Blood. 2012;119(16):3790-3798) IntroductionAspirin-exacerbated respiratory disease (AERD) is a distinctive syndrome characterized clinically by a triad of asthma, nasal polyposis, and aspirin sensitivity. It is a chronic inflammatory disease associated with eosinophilic infiltration of respiratory tissues, peripheral eosinophilia, and excessive production of cysteinyl leukotrienes (cysLTs), a class of inflammatory lipid mediators that are thought to contribute to several of the characteristic features of AERD. Individuals with this syndrome account for 4% to 11% of all adult patients with asthma, and for a disproportionate share (ϳ 30%) of patients with severe asthma. 1 The confirmatory diagnostic feature of AERD is an idiosyncratic respiratory reaction, including symptoms of acute bronchoconstriction, nasal congestion, and eye watering, on ingestion of aspirin or another nonselective cyclooxygenase (COX) inhibitor. Despite the strikingly consistent clinical phenotype of AERD, the pathogenesis of the disease remains unclear.CysLTs derive from the metabolism of arachidonic acid by effector cells of the innate immune system. In inflammatory leukocytes (neutrophils, monocytes, eosinophils, mast cells, and basophils), arachidonic acid is oxidized by 5-lipoxygenase (5-LO) to form the unstable intermediate leukotriene (LT)A 4 . 2 In neutrophils, LTA 4 is preferentially hydrolyzed by LTA 4 hydrolase to form LTB 4 , whereas in monocytes, mast cells, eosinophils, and basophils, it i...

Background Aspirin-exacerbated respiratory disease (AERD) is an inflammatory condition of the respiratory tract and is characterized by overproduction of leukotrienes (LT) and large numbers of circulating granulocyte-platelet complexes. LT production can be suppressed by prostaglandin E2 (PGE2) and the cyclic AMP-dependent protein kinase A (PKA). Objective To determine if PGE2-dependent control of LT production by granulocytes is dysregulated in AERD. Methods Granulocytes from well-characterized patients with and without AERD were activated ex vivo and subjected to a range of functional and biochemical analyses. Results Granulocytes from subjects with AERD generated more LTB4 and cysteinyl LTs than did granulocytes from controls with aspirin-tolerant asthma and controls without asthma. When compared with controls, granulocytes from subjects with AERD had comparable levels of EP2 protein expression and PGE2-mediated cAMP accumulation, yet were resistant to PGE2-mediated suppression of LT generation. Percentages of platelet-adherent neutrophils correlated positively with LTB4 generation and inversely with responsiveness to PGE2-mediated suppression of LTB4. The PKA inhibitor H89 potentiated LTB4 generation by control granulocytes but was inactive in granulocytes from individuals with AERD and had no effect on platelet P-selectin induction. Both tonic PKA activity and levels of PKA catalytic gamma subunit protein were significantly lower in granulocytes from individuals with AERD relative to those from controls. Conclusions Impaired granulocyte PKA function in AERD may lead to dysregulated control of 5-lipoxygenase activity by PGE2, whereas adherent platelets lead to increased production of LTs, which contributes to the features of persistent respiratory tract inflammation and LT overproduction.

We report the case of a seven-year-old boy with an ingested foreign body, which was retained within the appendix for a known duration of ten months, ultimately requiring appendectomy. The ingested foreign body was incidentally discovered by abdominal x-ray at an emergency room visit for constipation. Despite four bowel cleanouts, subsequent x-rays showed persistence of the foreign body in the right lower quadrant. While the patient did not have signs or symptoms of acute appendicitis, laparoscopic appendectomy was performed due to the risk of this foreign body causing appendicitis in the future. A small metallic object was found within the appendix upon removal. This case highlights the unique challenge presented by foreign body ingestions in non-verbal or developmentally challenged children and the importance of further diagnostic workup when concerns arise for potential retained foreign bodies.

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