Reduced infiltration and increased apoptosis of leukocytes at sites of inflammation by systemic administration of a membrane-permeable IkappaBalpha repressor.
OBJECTIVE
NF-kappaB activation is associated with several inflammatory disorders, including rheumatoid arthritis (RA), making this family of transcription factors a good target for the development of antiinflammatory treatments. Although inhibitors of the NF-kappaB pathway are currently available, their specificity has not been adequately determined. IkappaBalpha is a physiologic inhibitor of NF-kappaB and a potent repressor experimentally when expressed in a nondegradable form. We describe here a novel means for specifically regulating NF-kappaB activity in vivo by administering a chimeric molecule comprising the super-repressor IkappaBalpha (srIkappaBalpha) fused to the membrane-transducing domain of the human immunodeficiency virus Tat protein (Tat-srIkappaBalpha).


METHODS
The Wistar rat carrageenan-induced pleurisy model was used to assess the effects of in vivo administration of Tat-srIkappaBalpha on leukocyte infiltration and on cytokine and chemokine production.


RESULTS
Systemic administration of Tat-srIkappaBalpha diminished infiltration of leukocytes into the site of inflammation. Analysis of the recruited inflammatory cells confirmed uptake of the inhibitor and reduction of the NF-kappaB activity. These cells exhibited elevated caspase activity, suggesting that NF-kappaB is required for the survival of leukocytes at sites of inflammation. Analysis of exudates, while showing decreases in the production of the proinflammatory cytokines tumor necrosis factor alpha and interleukin-1beta, also revealed a significant increase in the production of the neutrophil chemoattractants cytokine-induced neutrophil chemoattractant 1 (CINC-1) and CINC-3 compared with controls. This result could reveal a previously unknown feedback mechanism in which infiltrating leukocytes may down-regulate local production of these chemokines.


CONCLUSIONS
These results provide new insights into the etiology of inflammation and establish a strategy for developing novel therapeutics by regulating the signaling activity of pathways known to function in RA.
Blackwell
Nathan M
NM
Bone and Joint Research Unit, William Harvey Research Institute, Queen Mary's School of Medicine and Dentistry, University of London, London, UK.
Sembi
Phupinder
P
Newson
Justine S
JS
Lawrence
Toby
T
Gilroy
Derek W
DW
Kabouridis
Panagiotis S
PS
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001172:Arthritis, Rheumatoid / Q000473:pathology; D002351:Carrageenan; D053148:Caspase 3; D020169:Caspases / Q000032:analysis; D004195:Disease Models, Animal; D015696:Gene Products, tat; D020672:I-kappa B Proteins / Q000008:administration & dosage* / Q000494:pharmacology; D007249:Inflammation / Q000139:chemically induced / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D000072000:NF-KappaB Inhibitor alpha; D009504:Neutrophils / Q000502:physiology; D010998:Pleurisy / Q000139:chemically induced; D051381:Rats; D035165:Transcription Factors, General / Q000037:antagonists & inhibitors* / Q000502:physiology
D015696:Gene Products, tat; D020672:I-kappa B Proteins; C000606204:NFKBIA protein, human; C000606206:Nfkbia protein, rat; D035165:Transcription Factors, General; D000072000:NF-KappaB Inhibitor alpha; D002351:Carrageenan; C505407:CASP3 protein, human; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases