TNF-alpha production by eosinophils in upper airways inflammation (nasal polyposis).
TNF-alpha is a cytokine with a wide spectrum of proinflammatory activities. Nasal polyps (NP), which occur in association with allergic rhinitis and asthma, are characterized by a marked infiltration of activated eosinophils, epithelial damage, and varying degrees of stromal fibrosis. By using Southern blot analysis after a reverse transcription-PCR, we detected a signal specific for TNF-alpha mRNA in five of seven NP samples, but not in control nasal mucosal samples. With in situ hybridization, we detected cells expressing mRNA specific for TNF-alpha in eight of thirteen NP samples, but not in four control samples. Counterstaining with chromotrope 2R demonstrated that virtually all cells expressing TNF-alpha message were eosinophils. The ratio of eosinophils expressing TNF-alpha to the total number of eosinophils varied greatly among tissues; as an average, we observed 24% TNF-alpha-positive eosinophils. Using a mAb against human TNF-alpha, we demonstrated TNF-alpha localization in 12 NP tissues (48.8 +/- 16.5 positive cells/mm2) but not in three control samples. Morphologically, cells localizing TNF-alpha were both mononucleated and polynucleated with only a small number of eosinophils, as determined by aniline blue counterstaining. Studies of purified blood eosinophils from a patient with hypereosinophilic syndrome and from four healthy donors indicated that TNF-alpha is produced, but rapidly secreted, so that TNF-alpha mRNA-positive cells contain little detectable protein. Furthermore, cells that retain detectable TNF-alpha may not contain sufficient TNF-alpha mRNA to be detected by using the probe developed for our studies. Together, these findings identify a novel mechanism by which eosinophils may contribute to mucosal inflammation and provide an approach to future investigation.
Finotto
S
S
Department of Pathology, McMaster University, Hamilton, Ontario, Canada.
Ohno
I
I
Marshall
J S
JS
Gauldie
J
J
Denburg
J A
JA
Dolovich
J
J
Clark
D A
DA
Jordana
M
M
D004802:Eosinophilia / Q000503:physiopathology; D004804:Eosinophils / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D017403:In Situ Hybridization; D009297:Nasal Mucosa / Q000503:physiopathology; D015508:Nasal Obstruction / Q000503:physiopathology; D009298:Nasal Polyps / Q000503:physiopathology*; D012333:RNA, Messenger / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha