Arachidonic acid metabolites in human nasal polyps

Is there a role for leukotriene antagonists in the prevention of recurrent nasal polyps?

PURPOSE OF REVIEW

The aim of this review is to provide the current available data for leukotriene receptor antagonists in the treatment of nasal polyps, the use in the postoperative therapy single or as an add-on to standard treatments.

RECENT FINDINGS

Surgical treatment of nasal polyps was refined in the last 30 years by the introduction of functional endoscopic sinus surgery and nasal endoscopy for monitoring nasal polyp patients. As the relapse is the main challenge and as nasal steroids only delay it, a more efficient treatment is needed. Leukotriene antagonists have effects on asthma and allergic rhinitis; preliminary data show some benefits in nasal polyps.

SUMMARY

In the surgery of nasal polyps, recurrence is the main problem. Steroids are the current standard therapy, but the limitations are obvious. The role of leukotrienes in the disorder of nasal polyps is well established now, and with the antagonists available, interest rose in treating nasal polyps. A total of 356 patients took part in several studies involving leukotriene antagonists in the nasal polyp population. Some studies have minor levels of evidence; the data show positive effects for patients in preoperative and postoperative studies and medical treatments. There were benefits as an add-on to steroids and data from allergic rhinitis studies also show possible synergism with antihistamines. There are hints for a positive effect on eosinophil inflammation, clinical symptom scores, nasal airflow, sneezing and postnasal drip. Although some effects are shown, more controlled studies are necessary for reliable data.

Montelukast as an adjunct to oral and inhaled steroid therapy in chronic nasal polyposis

OBJECTIVE

To examine the potential of montelukast, a leukotriene receptor antagonist, as an adjunct to oral and inhaled steroid in subjects with chronic nasal polyps.

STUDY DESIGN

Prospective, randomized controlled trial.

SUBJECTS AND METHODS

Thirty-eight consecutive adult patients with bilateral nasal polyps were randomized into two groups. Eighteen subjects were treated with oral prednisolone for 14 days and budenoside nasal spray for 8 weeks. Twenty subjects received similar treatment with additional oral montelukast for 8 weeks. Subjects completed a modified nasal ICSD symptom score at 8 and 12 weeks after beginning treatment and the SF-36 quality of life questionnaire at 12 weeks.

RESULTS

Symptom scores improved in both groups after treatment. Subjects treated with montelukast reported significantly less headache (P = 0.013), facial pain (P = 0.048) and sneezing (P = 0.03) than controls. Four weeks after completing treatment, no significant differences were recorded.

CONCLUSION

Montelukast therapy may have clinical benefit as an adjunct to oral and inhaled steroid in chronic nasal polyposis, but effects are not maintained after cessation of treatment.

Molecular and cellular staging for the severity of chronic rhinosinusitis

OBJECTIVES

To correlate objective and subjective clinical parameters with molecular, cellular, and histologic markers and to acknowledge the importance of these basic science parameters in a severity classification system for chronic rhinosinusitis (CRS).

STUDY DESIGN

Retrospective analysis of prospectively collected data of consecutive patients undergoing endoscopic sinus surgery for CRS in an academic institution.

METHODS

The preoperative computed tomography (CT) scans of all patients with CRS scheduled for surgery were graded according to Lund and Mackay. The patients completed a Sino-Nasal Outcome Test (SNOT)-20 questionnaire and had a preoperative nasal endoscopy performed, which was graded by assigning an endoscopy score according to Lanza and Kennedy. Subjects had a medical questionnaire regarding presence of aspirin sensitivity, allergic rhinitis, asthma, and medication usage. Subjects also underwent pulmonary function testing and had skin tests for allergies. At the time of surgery, blood was drawn to determine the level of peripheral eosinophilia and the degree of polymorphisms of the leukotriene C4 synthase gene. Sinus mucosal and polyp tissue was examined pathologically for the number of eosinophils per high-powered filed (HPF) and was stained for EG2 to determine the portion of activated eosinophils. Leukotriene C4 levels (pg/g of tissue) were determined using a sensitive competitive enzyme immunoassay. Endoscopy and SNOT-20 scores were reevaluated 1 year after surgery. Data were analyzed for disease-severity correlation to recommend a severity classification system for CRS that incorporates the contribution of clinical, molecular, cellular, and histologic parameters.

RESULTS

The presence of polyps resulted in higher preoperative CT scores and higher preoperative and postoperative symptom scores. Average preoperative CT scores were significantly higher in asthmatics and allergy patients and correlated with endoscopy scores. Patients with more than five eosinophils/HPF of sinus tissue had higher frequency of polyps and asthma and higher CT and endoscopy scores than patients without sinus tissue eosinophilia (less than or equal to 5 cells/HPF sinus tissue). The subgroup of patients with eosinophilic nasal polyps (eosinophilic hyperplastic rhinosinusitis) had more severe disease by CT and endoscopy than the subgroup of patients with nasal polyps (hyperplastic rhinosinusitis) but without eosinophilia. Similarly, patients without polyps but with tissue eosinophilia had more severe disease than patients without polyps and without eosinophilia. Leukotriene C4 levels were elevated in all patient groups. Symptom scores did not correlate with any of the parameters.

CONCLUSION

We suggest the following severity classification system for CRS: 1) eosinophilic chronic hyperplastic rhinosinusitis (ECHRS): patients with polyps and sinus tissue eosinophilia; 2) noneosinophilic chronic hyperplastic rhinosinusitis (NECHRS): patients with polyps but without sinus tissue eosinophilia; 3) eosinophilic chronic rhinosinusitis (ECRS): patients without polyps but with sinus tissue eosinophilia; 4) noneosinophilic chronic rhinosinusitis (NECRS): patients without polyps and without sinus tissue eosinophilia.

Pharmacological Management of Nasal Polyposis

Nasal polyposis affects nearly 4% of the total population in Western countries, and presents a real challenge to the physician because of its severity, chronicity and recurrence rate. Characteristic histomorphological features of polyps are an eosinophilic inflammation and the destruction of connective tissue; recent research has focused on cytokines, chemokines, growth factors and metalloproteinases to explain these features, as the aetiology of nasal polyposis remains largely unclear. Currently, topical and systemic corticosteroids are first-choice drug therapy approaches, and good evidence from controlled trials is available for topical, but not for systemic, corticosteroid therapy. Surgery is indicated if adequate drug treatment fails, which often needs to be maintained after surgery. There is limited experience for other drugs, such as antihistamines, leukotriene antagonists and frusemide (furosemide), which may be added to corticosteroid therapy in selected patients. Aspirin (acetylsalicylic acid) desensitisation may be a therapeutic option for patients who do not respond to corticosteroids or surgery. Recently, antibiotics such as macrolides have been suggested to have therapeutic activity based on their anti-inflammatory properties but large-scale controlled trials are lacking. New approaches are currently evolving, specifically targeting eosinophilic recruitment (chemokine receptor 3, eotaxin) and inflammation (interleukin-4, -5, -13), immunoglobulin-E, or tissue remodeling by reducing the activity of metalloproteinases. This review summarises current knowledge on pathogenesis as well as established and future approaches in the pharmacological management of bilateral eosinophilic nasal polyposis.

Cysteinyl leukotriene expression in chronic hyperplastic sinusitis-nasal polyposis: importance to eosinophilia and asthma

BACKGROUND

Chronic hyperplastic eosinophilic sinusitis (CHS) results from the unregulated proliferation of eosinophils, T(H)2-like lymphocytes, goblet cells, mast cells, and fibroblasts and is present in most patients with asthma. The frequent coexpression of these disorders and their shared pathophysiology suggests that these are similar disorders affecting the upper and lower airways.

OBJECTIVE

We evaluated the expression of cysteinyl leukotrienes (CysLTs) in sinus tissue from subjects with CHS compared with that seen in healthy sinus tissue.

METHODS

Nasal polyp and sinus tissue was evaluated from 58 individuals undergoing elective functional endoscopic sinus surgery. The diagnosis of CHS was demonstrated through the presence of eosinophilia and activated (EG2(+)) eosinophils, as determined by means of tissue immunohistochemistry. Data were compared with those from both nasal polyp tissue without eosinophilic inflammation and healthy control sinus tissue obtained from the sinus ostiomeatal complex at the time of surgery for unrelated disorders. CysLTs were quantified by means of ELISA in lipid-extracted tissue. Activation of the metabolic pathway leading to CysLT synthesis was demonstrated by ribonuclease protection. Subjects were genotyped for leukotriene C(4) (LTC(4)) synthase C-to-A promoter polymorphism.

RESULTS

CysLT concentrations were significantly higher in tissue obtained from subjects with CHS (776.7 +/- 201.9 pg/g tissue) compared with that seen in healthy sinus tissue (355.7 +/- 101.6 pg/g tissue, P <.03). CysLT concentrations within noneosinophilic nasal polyps (328.0 +/- 116.4 pg/g tissue) were similar to those in control tissue. The presence of CysLTs in CHS was associated with increased expression of LTC(4) synthase mRNA. The C-to-A promoter polymorphism was associated with trends toward the increased presence of CHS and CysLTs.

CONCLUSIONS

CHS is characterized by the increased presence of CysLTs when compared with concentrations seen in tissue from patients with chronic inflammatory sinusitis or healthy sinus tissue. These studies support the use of LT modifiers as anti-inflammatory agents that might have clinical benefit in patients with these disorders.

Cysteinyl leukotrienes in chronic hyperplastic rhinosinusitis

OBJECTIVES

Our study was designed to demonstrate that, similar to asthma, eosinophilic chronic rhinosinusitis is a disease characterized by activation and the expression of cysteinyl leukotrienes (LTs).

METHODS

Nasal polyp tissue was evaluated from 28 consecutive individuals undergoing elective polypectomy in whom neutrophils were not present on pathologic examination. Tissue was analyzed for pathosis with particular attention to the presence of eosinophils. Patients with moderate to high levels of mucosal eosinophils were classified as having eosinophilic rhinosinusitis (ECRS). Those with few or absent mucosal eosinophils were classified as having noneosinophilic rhinosinusitis (NECRS). Cysteinyl LTs were quantified by a sensitive competitive enzyme immunoassay, and the levels of cysteinyl LTs were compared in the groups.

RESULTS

There were 20 patients with ECRS and 8 patients with NECRS. Cysteinyl LTs were identified in polyp tissue from 24 of 28 subjects and were >5 pg/gm tissue in 15 of 28. The average level of LTC(4) in patients with few mucosal eosinophils was 38.3 pg/g. The average amount in those with moderate to large amounts of mucosal eosinophils was 36.7 pg/g. There was no significant difference between the 2 groups.

CONCLUSION

ECRS and NECRS can be considered diseases of excessive expression of cysteinyl LTs. LT expression occurs in patients who demonstrate few or no mucosal eosinophils, which indicates that cell lines other than eosinophils may be responsible for LT production in chronic rhinosinusitis.

Arachidonic acid metabolism in nasal tissue and peripheral blood cells in aspirin intolerant asthmatics

Aspirin intolerance (AI) is characterized by polypous rhinosinusitis, bronchial asthma and adverse reactions to aspirin. The common intolerance to all cyclo-oxygenase inhibitors allows us to focus study of the pathogenesis of AI on the metabolism of arachidonic acid (AA). We studied the metabolism of AA in nine aspirin intolerant asthmatics (AIA) and eight healthy volunteers (controls) by measuring prostaglandin E2 (PGE2) and peptido-leukotrienes (pLT = LTC4/D4/E4) in nasal tissue and peripheral blood cells (PBCs) using a specific immunoassay. In all patients with AI the tests were performed before and after bronchial provocation with lysine-ASA. In the control group the tests were done before and after 500 mg ASA p.o. The release of pLT in nasal polyps of AIA was found to be significantly higher than in normal mucosa of AIAs and controls. In every tissue a significant increase of pLT after aspirin challenge was observed. Nasal polyps of AIA show a significantly lower release of PGE2 than normal mucosa of AIAs and controls. Peripheral blood cells of AIA show a significantly higher release of pLT and a significantly lower release of PGE2 than PBCs of controls. Therefore clinical manifestations of AI may be based on an alteration of AA metabolism in AIA.

Cyclooxygenase and lipoxygenase metabolite generation in nasal polyps

A role of prostaglandins (PGs) and leukotrienes (LTs) in the pathogenesis of nasal polyps has been recently suggested. Cyclooxygenase (CO) products (thromboxane B2, PGE2 and 6-keto PGF1 alpha) and lipoxygenase (LO) products (LTB4 and LTC4) were investigated by radioimmunoassay in polyps, hypertrophic turbinates and nasal mucosa from 14 patients with non-allergic (n = 6), allergic chronic rhinitis (n = 6) and aspirin-sensitive asthma (ASA) (n = 2), who underwent polypectomy. In all tissues CO metabolite levels were found higher than LO products (P < 0.01). Nasal polyps showed a significantly lower (P < 0.05) arachidonic acid (AA) metabolism in comparison to nasal mucosa. In polyps of allergic patients significantly higher LTB4 levels (P < 0.001) and a tendency to produce higher amounts of CO products in comparison to non-allergic subjects were observed, whereas in turbinates of non-allergic patients LT levels were significantly higher in comparison to those of allergic ones (P < 0.01). In ASA patients a decreased CO/LO ratio was found supporting the hypothesis of an imbalance of AA metabolism in this syndrome. These findings seem to indicate that the occurrence of nasal polyps may represent the result of different chronic inflammatory stimuli, regulated in part by AA metabolites.

Inhibition of mediator and cytokine release from dispersed nasal polyp cells by terfenadine

The mechanism of action of H1-blockers requires elucidation because they may possess properties unrelated to the blockage of histamine at its receptor level. A study was performed with enzymatically dispersed cells obtained from nasal polyps to examine the effect of terfenadine (0.1-10 mumol) on the release of leukotrienes (LT) (LTC4/D4 and LTB4) after stimulation by anti-IgE, and on the spontaneous release of cytokines (granulocyte/macrophage-colony stimulating factor [GM-CSF] and tumor necrosis factor-alpha [TNF-alpha]) released from cells cultured for 6 h. Terfenadine inhibited significantly, and in a dose-dependent manner, the release of LTC4/D4, LTB4, TNF-alpha, and GM-CSF. IC50 values were determined for LTC4/D4 (8 mumol), LTB4 (9.9 mumol), TNF-alpha (6.1 mumol), and GM-CSF (4 mumol). Terfenadine was found to possess new antiallergic properties with a novel in vitro model which mimics more closely inflammatory cells of allergic rhinitis or asthma.

Arachidonic acid metabolites and sinonasal polyposis. I. Possible prognostic value

PURPOSE

The etiology of sinonasal polyps is sometimes obscure. This study was undertaken to evaluate the potential role of arachidonic acid metabolites (AAm) on recurrent polyposis.

MATERIALS AND METHODS

Tissue production of prostaglandin E2 (PGE2), 6-keto-prostaglandin F1-alpha (PGI2), thromboxane A2 (TxA2), and leukotriene C4 (LTC4) by nasal mucosa was determined by radioimmunoassay in 27 patients with sinonasal polyposis (SNp) and in 10 volunteers.

RESULTS

The group of patients with SNp with the evidence of recurrences in postoperative period (Group 1) showed significantly lower PGE2 concentrations than group of patients with SNp recurrences (Group 2). The differences in concentrations of PGI2 in mentioned groups were insignificant. In comparison with other groups, a group of patients who underwent surgery several times for SNp (Group 4) had a higher mean TxA2 concentration. The LTC4 concentrations were the highest in groups of patients where SNp recurrences were observed. When the incidence of polyposis recurrences (within 18 months after surgery) was correlated with the level of LTC4 production at the time of surgery, the rate of recurrence was significantly higher in patients with increased LTC4 level than in those with normal LTC4 levels.

CONCLUSIONS

LTC4 might have a prognostic value. The possible role of AAm in occurrence of SNp is apparent and suggests possible role for medical intervention.