This study found that immune deficiency results in increased neointimal formation (thickening of the artery wall) after arterial injury in mice. Adoptive transfer of B cells from wild type mice to immune deficient Rag-1 KO mice inhibited neointimal formation in the Rag-1 KO mice after arterial injury, regardless of diet. The presence of immunoglobulins like IgM and IgG increased in the injured arteries of wild type mice and B cell reconstituted Rag-1 KO mice. This suggests that humoral aspects of the immune system mediated by B cells and immunoglobulins may play a role in inhibiting neointimal formation after arterial injury.

1. Inhibitory effect on arterial injury-induced neointimal
formation by adoptive B cell transfer in Rag-1 KO mice
P. Dimayuga, B. Cercek, S. Oguchi, G. N. Fredrikson,
J. Yano, P. K. Shah, S. Jovinge, J. Nilsson
Department of Medicine, Lund University, University Hospital MAS, Malmö, Sweden
Atherosclerosis Research Center, Cedars-Sinai Medical Center, Los Angeles, California;
Department of Biomedical Laboratory Science, Health and Society,
Malmö University, Malmö, Sweden

2. General Findings:
• Immune-deficiency results in increased neointimal
formation after arterial injury in mice.
• Humoral aspects of the immune system may be
involved in inhibiting neointimal formation:
B cells produce “natural antibodies” ?

3. Background
•T cell deficiency results in increased neointima in
injured rats (antibodies against T cell CD markers and
nu/nu rats)
Hansson, et al PNAS/Circ 1991
Remskar et al Circ Res. 2001
•CD40-CD40 ligand interaction mediates response to
arterial injury
Remskar et al Circ Res. 2001
•B cells implicated in bone-healing response as a
limiting factor
Marusic, et al LI 2000
•Homologous oxLDL immunization reduces
neointimal formation in injured hypercholesterolemic
rabbits
Nilsson et al JACC 1997

4. Arterial Injury
Activation of signaling cascades
Increased expression of inflammatory proteins/
medial SMC activation
Immune functions
physiologic IFN-γ
Immunoglobulins
Immune-deficiency
Vascular repair and Intimal formation

5. Hypothesis: B cells are involved in the response to
arterial injury.
Methods:
•Injure Rag-1 KO mice and compare to WT mice.
•“Rescue” Rag-1 KO mice with B cell reconstitution
from spleens of WT
•Repeat rescue with donor and recipients on western
diet

6. Arterial Cuff Injury
Tygon tube
Right carotid artery

7. harvest spleen from WT mice
squeeze through mesh to isolate cells
add paramagnetic beads
coated with T cell antibody
expose solution to magnetic field and
aspirate supe = negative selection of B cells
classify cell population
and/or spin and concentrate
Inject cells into Rag-1 KO mice via tail vein
Cell enrichment procedure

8. *p<0.05 vs. WT NC; †
p<0.05 vs. Rag NC
B cell reconstitution inhibits intimal formation
in Rag-1 KO mice fed normal chow

9. B cell reconstitution inhibits intimal formation
in Rag-1 KO mice fed western diet
*p<0.05 vs. WT HC; †
p<0.05 vs. Rag HC

10. WT HC Rag-KO Rag-1 KO Brec
Effect of B cell reconstitution on
intimal formation in injured Rag-1 KO mice

11. Neointimal stain for SM α-actin
(western diet-fed mice)
WT Rag-1 KO Rag-1 KO Brec

12. Mφ stain in arteries 21 days after injury
(western diet-fed mice)
WT Rag-1 KO Rag-1 KO Brec

13. IgM in injured arteries of western diet-fed mice
Left contra-lateral (uninjured) Injured right carotid artery
No reconstitution B cell reconstituted
WT
Rag-1 KO

14. WT
Rag-1 KO
Left contra-lateral (uninjured) Injured right carotid artery
No reconstitution B cell reconstituted
IgG in injured arteries of western diet-fed mice

15. Relative immunoglobulin levels
in B cell reconstituted mice

16. Summary of Study
•Neointimal formation after injury is inhibited in Rag-1
KO mice reconstituted with B cells regardless of diet.
•Immunoglobulin presence is increased in injured
arteries of WT mice and in B cell reconstituted Rag-1
KO mice.