Interleukin-10 fails to modulate low shear stress-induced neointimal hyperplasia.
BACKGROUND
Overexpression of the anti-inflammatory cytokine interleukin-10 (IL-10) blocks atherosclerotic events in vivo, and IL-10 has been recently hailed as an "immunologic scalpel" for atherosclerosis. Alternatively, mice lacking IL-10 receiving atherogenic diets have increased occlusive lesions. It remains unclear whether such IL-10 modulation broadly applies to other forms of occlusive arterial remodeling. We hypothesized that lack of IL-10 would exacerbate, and exogenous or overexpression of IL-10 would abrogate low shear stress-induced neointimal hyperplasia (NIH).


METHODS
Wild-type (WT) and IL-10-deficient (IL-10-/-) mice underwent unilateral common carotid artery (CCA) ligation. Low shear stress in the patent ligated artery results in remodeling and formation of neointima containing BrdU and SMC alpha-actin-positive cells. Additional groups of WT mice underwent CCA ligation and were treated daily with intraperitoneal saline or 1 microg of human IL-10. Chronic delivery gene therapy approaches were also utilized to define the role of IL-10 signaling. WT mice were treated adventitially with 1 x 10(10) adenovirus/green fluorescent protein (Ad/gfp) and an Ad/empty control to confirm the veracity of adventitial delivery. Then, Ad viral IL-10 (vIL-10), Ad/empty, and virus buffer alone were applied directly to the adventitia of the CAA immediately following ligation. In separate experiments, 1 x 10(10) Ad/empty or Ad/vIL-10 was injected intramuscularly. CCAs were perfusion fixed 28 days postligation, the time at which NIH is near maximum.


RESULTS
IL-10-/- mice developed identical NIH areas compared to WT controls. Mice receiving IL-10 demonstrated NIH equivalent to saline controls. Mice receiving intramuscular or adventitial Ad/IL-10 developed high serum levels of IL-10 yet formed NIH areas similar to those of controls. Serum IL-10 levels were significantly higher (P = 0.04) with adventitial delivery. Mice treated adventitially with Ad/gfp showed reliable transfection of cells within the adventitia of CAA. No antibody to human IL-10 was found in the sera of intraperitoneal IL-10-treated mice, which failed to attenuate NIH.


CONCLUSIONS
Under the conditions of this experiment, lack of IL-10 does not exacerbate low shear stress-induced NIH, nor does exogenous administration or overexpression of IL-10 attenuate it. Despite high serum levels of vIL-10 in mice treated with ad/vIL-10 adventitially, there appears to be no therapeutic effect despite the confirmed transfection of adventitial cells. Discrepancies between these findings and previous research may be related to IL-10 dosing, inflammation induced by the adenoviral vector, or disparities between the NIH models.
Rectenwald
John E
JE
University of Florida College of Medicine, Gainesville, Florida 32610, USA.
Minter
Rebecca M
RM
Moldawer
Lyle L
LL
Abouhamze
Zaher
Z
La Face
Drake
D
Hutchins
Elizabeth
E
Huber
Thomas S
TS
Seeger
James M
JM
Ozaki
C Keith
CK
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002340:Carotid Artery Diseases / Q000188:drug therapy / Q000473:pathology*; D017536:Carotid Artery, Common / Q000473:pathology*; D005260:Female; D015316:Genetic Therapy; D049452:Green Fluorescent Proteins; D006965:Hyperplasia; D007202:Indicators and Reagents / Q000378:metabolism; D016753:Interleukin-10 / Q000235:genetics* / Q000494:pharmacology; D008026:Ligation; D008164:Luminescent Proteins / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013314:Stress, Mechanical; D017539:Tunica Intima / Q000473:pathology*
D007202:Indicators and Reagents; D008164:Luminescent Proteins; D016753:Interleukin-10; D049452:Green Fluorescent Proteins