Generation and Metabolism of Leukotrienes in Granulocytes of Patients with Cystic Fibrosis

Abstract

We studied the generation and metabolism of lipoxygenase products in peripheral granulocytes from children suffering from cystic fibrosis (CF). Peripheral granulocytes were stimulated at different times (days) before and during anti-infectious treatment with the Ca ionophore (7.5 μM, 5 and 20 min), opsonized zymosan (2 mg) and arachidonic acid (50 μM); the amount of lipoxygenase products in the cell supernatants was determined by high performance liquid chromatography. Granulocytes from patients with CF, compared to an age-matched control group, showed an increased ω-oxidation of the synthesized leukotriene (LTB₄) into 20-OH- and 20-COOH-LTB₄ after stimulation with the Ca ionophore (ratio of LTB₄ versus ω-oxidated products in patients with CF: 0.77 ± 0.07, mean ± SEM, n = 11; control group: 1.07 ± 0.1, n = 11, p < 0.01) whereas the combined amounts of LTB₄ and its ω-oxidated products did not differ significantly. A comparable profile was observed with opsonized zymosan. Stimulation of the cells with the Ca ionophore combined with arachidonic acid led to a significantly increased formation of lipoxygenase products in the patient group, whereas only a slight enhancement was observed in the control group. During the 14-day anti-infectious treatment a normalization of the altered pattern was observed. 12-Hydroxyeicosatetraenoic acid (12-HETE) production from platelets within the granulocyte fraction was significantly depressed in the CF group compared to the controls (38.5 ± 12.5 versus 339 ± 93 ng/5 ± 10⁶ cells, p < 0.005). Within the CF group a strong correlation between the release of LTB₄ and its metabolites, the production of 12-HETE and clinical (e.g. pO₂, FEV₁) and laboratory findings (e.g. IgE and IgG levels, C-reactive protein) was established. Our data suggest that the inflammatory process in patients with CF is associated with an alteration of the lipoxygenase pathway of granulocytes which correlates with the clinical signs of inflammation.

20-Hydroxy- and 20-carboxy-leukotriene (LT) B4 downregulate LTB4-mediated responses of human neutrophils and eosinophils

“…In contrast, some clinical trials involving LTB 4 modulators reported pulmonary infections as severe adverse events indicating that in humans, LTB 4 should not be regarded as a pro‐inflammatory effector but rather as a booster of innate immunity and host defense. Of note, the ω‐LTB 4 /LTB 4 ratio is increased in neutrophils purified from the blood of cystic fibrosis patients and from severely burned patients, two conditions in which infections are not well controlled. Furthermore, 20‐OH‐LTB 4 and 20‐COOH‐LTB 4 were detected in the sputum of patients with cystic fibrosis in larger amount than LTB 4 itself (55% 20‐COOH‐LTB 4 :20% 20‐OH‐LTB 4 :25% LTB 4 ) .…”

Neutrophils in cystic fibrosis

“…Alternatively, chemotaxis in CF might be impaired due to differential responsiveness to stimulants or chemoattractants. Previous studies have suggested that the lipoxygenase pathway and resulting leukotrienes are involved in CF lung disease (Saak et al, 1990). Leukotriene B4 (LTB 4 ) has been further associated with impaired neutrophil chemotaxis in patients with rheumatoid arthritis, chronic bowel disease and CF (Lawrence and Sorrelli, 1992).…”

Effect of cystic fibrosis exacerbations on neutrophil function

“…For example, neutrophils and eosinophils isolated from CF patients have been shown to have an altered arachidonic acid turnover [12], and an increased release of myeloperoxidase (MPO), eosinophil cationic protein (ECP), and eosinophil protein X (EPX) [13]. In addition, isolated peripheral neutrophils from CF patients generated higher levels of elastase when exposed to stimuli such as IL-8 and TNFa compared to neutrophils isolated from controls [14].…”