CD69 limits the severity of cardiomyopathy after autoimmune myocarditis.
BACKGROUND
Experimental autoimmune myocarditis (EAM), a mouse model of post-infectious cardiomyopathy, reflects mechanisms of inflammatory cardiomyopathy in humans. EAM is characterized by an infiltration of inflammatory cells into the myocardium that can be followed by myocyte fibrosis, edema, and necrosis, leading to ventricular wall dysfunction and heart failure. Different data indicate that CD69 exerts an important immunoregulatory effect in vivo. However, the possible role of CD69 in autoimmune myocarditis has not been studied.


RESULTS
We have explored the role of the leukocyte regulatory molecule CD69 in the inflammation that leads to cardiac dysfunction after myocardial injury in EAM. We have found that after induction of EAM, the draining lymph nodes from CD69-deficient mice developed an exacerbated Th17 inflammatory response, resulting in increases in the numbers of infiltrating leukocytes in the myocardium. In the chronic phase of EAM, transthoracic echocardiography revealed a significantly reduced left ventricular fractional shortening and a decreased ejection fraction in CD69-deficient mice, indicative of an impaired cardiac contractility. This condition was accompanied by a greater extent of myocardial fibrosis, an elevated number of sinus pauses on ECG, and an enhanced ratio of heart weight to body weight in CD69-/- mice. Moreover, both bone marrow transplantation and adoptive transfer of Th17 cells isolated from immunized CD69-/- mice with EAM into naive wild-type recipients reproduced the severity of the disease, demonstrating that CD69 exerts its function within the lymphocyte compartment.


CONCLUSIONS
Our findings indicate that CD69 negatively regulates heart-specific Th17 responses, cardiac inflammation, and heart failure progression in EAM.
Cruz-Adalia
Aranzazu
A
Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III, Melchor Fernández Almagro, Madrid, Spain.
Jiménez-Borreguero
Luis Jesús
LJ
Ramírez-Huesca
Marta
M
Chico-Calero
Isabel
I
Barreiro
Olga
O
López-Conesa
Erica
E
Fresno
Manuel
M
Sánchez-Madrid
Francisco
F
Martín
Pilar
P
D000818:Animals; D015703:Antigens, CD / Q000235:genetics; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics; D001327:Autoimmune Diseases / Q000235:genetics / Q000276:immunology / Q000503:physiopathology*; D003433:Crosses, Genetic; D004719:Endomyocardial Fibrosis / Q000276:immunology / Q000503:physiopathology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D037181:Lectins, C-Type / Q000172:deficiency* / Q000235:genetics; D008198:Lymph Nodes / Q000166:cytology / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D009205:Myocarditis / Q000235:genetics / Q000276:immunology / Q000503:physiopathology*; D018995:Myosin Heavy Chains / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology; D012720:Severity of Illness Index; D013154:Spleen / Q000166:cytology / Q000502:physiology; D000099192:CD69 Antigens
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D037181:Lectins, C-Type; D018995:Myosin Heavy Chains; D010446:Peptide Fragments; D000099192:CD69 Antigens