Inhibition of tumor necrosis factor-alpha-induced intercellular adhesion molecule-1 expression in diabetic rats: role of insulin.
OBJECTIVE
The effects of insulin on intercellular adhesion molecule (ICAM)-1-mediated leukocyte adhesion and migration were investigated.


METHODS
Diabetic rats (alloxan, 42 mg/kg, i. v., 42 days), matching controls, and insulin (NPH, 2 IU/day for 12 days) treated diabetic rats were used. The internal spermatic fascia of the animals was used for direct vital microscopy of the microcirculation, and for quantitation of ICAM-1 expression by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR). Experiments were performed 2 h after the local injection of recombinant rat tumor necrosis factor-alpha (5 ng).


RESULTS
Relative to controls (C), diabetic (D) rats exhibited a reduced number of adhered (D: 2.2 +/- 0.4 and C: 14.1 +/- 0.6 cells/100 microm venule length, P < 0.001) and migrated leukocytes (D: 1.1 +/- 0.3 and C: 6.3 +/- 0.6 cells/1,000 microm (2), P < 0.001) accompanied by low expression of ICAM-1 in postcapillary venules (D: 18 +/- 4 and C: 51 +/- 7 arbitrary units, P < 0.001). There were no differences in ICAM-1 mRNA levels (D: 1.01 +/- 0.05 and C: 1.18 +/- 0.09 ICAM-1/GAPDH ratio, P > 0.05). Treatment of diabetic rats with insulin restored the number of adhered (10.9 +/- 1.2 cells/100 microm venule length), and migrated leukocytes (4.0 +/- 0.3 cells/1,000 microm (2)) as well as ICAM-1 expression (45 +/- 3 arbitrary units). Levels of mRNA for ICAM-1 remained unchanged after treatment (1.15 +/- 0.04 ICAM-1/GAPDH ratio).


CONCLUSIONS
Insulin modulates TNF-alpha-induced ICAM-1 expression on microvascular endothelium controlling, therefore, leukocyte adhesion and migration.
Anjos-Valotta
E A
EA
Research Division, Institute of Heart (InCor), LIM-11, University of São Paulo Medical School, Av. Dr. Enéas de Carvalho Aguiar 44, 05403-000 São Paulo, SP, Brazil.
Martins
J O
JO
Oliveira
M A
MA
Casolari
D A
DA
Britto
L R G
LR
Tostes
R C
RC
Fortes
Z B
ZB
Sannomiya
P
P
D000818:Animals; D002448:Cell Adhesion; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism* / Q000628:therapy; D004730:Endothelium, Vascular / Q000378:metabolism; D007150:Immunohistochemistry; D007328:Insulin / Q000378:metabolism*; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis*; D007962:Leukocytes / Q000166:cytology; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
D007328:Insulin; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1