Therapeutic effects of cysteine protease inhibition in allergic lung inflammation: inhibition of allergen-specific T lymphocyte migration.
OBJECTIVE
We have evaluated the effects of the broad-spectrum cysteine protease inhibitor E64 on allergic lung inflammation in the mouse ovalbumin model of human asthma. We have also characterised membrane-associated cathepsin enzyme activity on a range of cell types.


METHODS
Balb/C mice, E64 and CA074, various cell lines.


METHODS
E64 was administered by subcutaneous minipump into ovalbumin-sensitised mice prior to intranasal ovalbumin challenge. The effect of E64 on ovalbumin-induced inflammation in vivo and ovalbumin-specific T cell proliferation in vitro and ex vivo was examined. Membrane-associated cathepsin activity on various cell types was measured.


RESULTS
E64 treatment (0.36-0.48 mg/day) led to a significant reduction in eosinophil numbers and lung weights in the mouse model. Histological examination of lungs confirmed the anti-inflammatory effect. E64 greatly reduced ovalbumin-specific T cell numbers in the lymph nodes draining the lung following intranasal challenge whilst an accumulation of these T cells was found in the 'priming' lymph nodes. An analysis of various cells involved in lymphocyte priming and migration revealed that monocytes, dendritic cells and endothelial cells express high levels of membrane-associated cathepsin B activity.


CONCLUSIONS
Since E64 is not cell permeable and does not inhibit antigen-induced T cell proliferation in vitro or in vivo, the data indicate that membrane-associated cysteine proteases, possibly cathepsin B, may regulate T lymphocyte migration in vivo.
Layton
G T
GT
British Biotech Pharmaceuticals plc, Cowley, Oxford, UK. layton@britbio.co.uk
Harris
S J
SJ
Bland
F A
FA
Lee
S R
SR
Fearn
S
S
Kaleta
J
J
Wood
M L
ML
Bond
A
A
Ward
G
G
D000485:Allergens / Q000494:pharmacology*; D000818:Animals; D002401:Cathepsin B / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000627:therapeutic use*; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D006412:Hematopoietic Stem Cells / Q000187:drug effects; D007930:Leucine / Q000031:analogs & derivatives / Q000627:therapeutic use; D008168:Lung / Q000201:enzymology / Q000473:pathology; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000276:immunology; D011014:Pneumonia / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D013601:T-Lymphocytes / Q000187:drug effects*
D000485:Allergens; D015853:Cysteine Proteinase Inhibitors; D010047:Ovalbumin; D002401:Cathepsin B; D007930:Leucine; C024974:E 64