Functional role of NKX2-5 and Smad6 expression in developing rheumatic heart disease

X.-L. Lu, X.-L. Yao, C.-Y. Yan, Q.-L. Wan, Y.-M. Li

Department of Cardiology, Huaihe Hospital of Henan University, Kaifeng, Henan Province, China. liyanming199@hotmail.com

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• Cardiology

 26957275 OBJECTIVE: Rheumatic heart disease (RHD) results due to the cross reaction of the host immune system when it develops immunity against group A streptococcal infection. This autoimmune disease progress with different pathological conditions and the genes associated with it are still less understood.

MATERIALS AND METHODS: To understand the role of NKX2-5 and Smad-6 in developing an RHD, we successfully developed RHD model using BALB/c mice and we evaluate the expression of NKX2-5 and Smad-6 in different conditions.

RESULTS: The disease conditions are confirmed through histological sectioning of RHD heart tissue with its associated Aschoff bodies. The histological of control heart tissue in the absence of NKX2-5 looks abnormal with an enlarged nucleus and in the absence of Smad-6 the solid nature of heart tissue loosens. The mice developed a complex form of acute RHD with tissue hardening in the absence of either NKX2-5 or Smad-6 which are confirmed in NKX2-5 or Smad-6 null mice. Immunohistochemical studies reveal that the NKX2-5 and Smad-6 expression get down regulated on developing with RHD. Through experiments, we detected that both Nkx2-5 and Smad-6 are both inter-dependable and it negatively regulated each other by inhibiting them. In the absence of NKX2-5 or Smad-6, a severe form of RHD is observed together with down-regulation of either NKX2-5 or Smad-6.

CONCLUSIONS: The present investigation of NKX2-5 and Smad-6 in RHD provides a new insight of data that helps to understand the disease pathogenesis.

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