Morphological and immunological evidence of a unique selective production and endoplasmic reticular accumulation of interleukin-1alpha in rat peritoneal macrophages induced by Pseudomonas aeruginosa exotoxin A.
The immunotoxicity of Pseudomonas aeruginosa exotoxin A (ETA) on macrophages was evaluated by incubating rat peritoneal macrophages (RPM) with 1-100 ng/ml ETA for 3-60 h. Although the overall changes in cell viability and DNA, RNA, and protein synthesis of the ETA-treated RPM (E-RPM) were reduced in a dose- and time-dependent manner, there was a transient but evident rebound in RNA and/or protein synthesis at 24-36 h post-incubation (HPI) at 1-50 ng/ml ETA. However, a more apparent enhancement appeared in RNA and protein synthesis at 36-48 HPI in 10 and 50 ng/ml E-RPM after normalized on the basis of viable cell. Most 50-100 ng/ml E-RPM underwent necrosis/apoptosis before 24 HPI. By 36 HPI, 41% of 10 ng/ml E-RPM remained viable but were full of cytoplasmic granules due to the accumulation of glycoprotein in segmentally dilated endoplasmic reticulum. Immunological staining of the granules revealed strong IL-1alpha but weak or no signals for IL-1beta, IL-1 receptor antagonist, IL-6, and TNF-alpha. A time-dependent increase in IL-1alpha but no IL-1beta was detected in cell lysate of 10 ng/ml E-RPM; however, neither IL-1alpha nor IL-1beta was detected in culture supernatant. Thus, besides cytopathic and functional effects, ETA could induce a unique selective production and endoplasmic reticular accumulation of IL-1alpha in RPM.
Graduate Institute of Veterinary Medicine, National Taiwan University, 106, ROC, Taipei, Taiwan.
Yen-Te
YT
Huang
Chian-Ren
CR
Jeng
Chiung-Hsiang
CH
Cheng
Ling-Ling
LL
Chueh
Jiuan Judy
JJ
Liu
Victor Fei
VF
Pang
D036002:ADP Ribose Transferases / Q000276:immunology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology; D001427:Bacterial Toxins / Q000276:immunology*; D002470:Cell Survival / Q000276:immunology; D004396:Coloring Agents / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D053938:DNA Fragmentation / Q000276:immunology; D004721:Endoplasmic Reticulum / Q000276:immunology / Q000378:metabolism*; D005098:Exotoxins / Q000276:immunology*; D005562:Formazans / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D007375:Interleukin-1 / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000276:immunology / Q000378:metabolism*; D008297:Male; D008855:Microscopy, Electron, Scanning; D011550:Pseudomonas aeruginosa / Q000276:immunology*; D012313:RNA / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D013047:Specific Pathogen-Free Organisms; D013778:Tetrazolium Salts / Q000378:metabolism; D014343:Trypan Blue / Q000378:metabolism; D037521:Virulence Factors / Q000276:immunology*; D000097668:Pseudomonas aeruginosa Exotoxin A
D036002:ADP Ribose Transferases; D001427:Bacterial Toxins; D004396:Coloring Agents; D004247:DNA; D005098:Exotoxins; D005562:Formazans; D007375:Interleukin-1; D012313:RNA; D013778:Tetrazolium Salts; D014343:Trypan Blue; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A; C079782:MTT formazan