The Myocardium of Fetuses with Endocardial Fibroelastosis Contains Fewer B and T Lymphocytes than Normal Control Myocardium

Abstract

The observation that endocardial fibroelastosis (EFE) can result from an immune response to maternal autoantibody deposition in the fetal myocardium raises the possibility that the fetal immune system may contribute to the pathogenesis of idiopathic EFE and dilated cardiomyopathy (DCM). This study sought to characterize myocardial immune cell presence in fetuses and neonates with idiopathic EFE + DCM, in those with EFE + structural heart disease, and in normal control subjects. Paraffin tissue sections from fetuses identified from the pathology database were stained for B cell, T cell, macrophage, and general hematopoietic cell surface markers. Of the 14 fetuses included in the study, 5 had EFE + DCM, 4 had EFE + structural heart disease, and 5 were normal control fetuses. The EFE + DCM group had fewer B cells than the control group (0.15 vs. 0.44 cells/mm(2); p = 0.005). The EFE + heart disease group had both fewer B cells (0.18 vs. 0.44 cells/mm(2); p = 0.08) and T cells (0.29 vs. 0.80 cells/mm(2); p = 0.04) than the control group. The CD4/CD8 ratio was similar in the EFE + DCM and EFE + heart disease groups (1.0 vs. 0.9; p = 0.17) but higher in the EFE + DCM group than in the control group (0.9 vs. 0.3; p = 0.03). The myocardium of fetuses with EFE contains fewer B and T lymphocytes than normal control fetuses.

Endocardial fibroelastosis and dilated cardiomyopathy – the past and future of the interface between histology and genetics

“…This process can be triggered by various factors; therefore, some authors consider the term of idiopathic EFE to be more appropriate. The first identified damaging factors for EFE are Coxsackie and mumps virus, genetic syndromes, autoimmune disease, metabolic and vascular disorders [ 18 , 19 ].…”

“…Patients born from mothers with anti-Ro or anti-La antibodies develop fibroelastosis associated with different types of cardiomyopathies. Their myocardium specimens were found to have increased IgG, IgM and T-lymphocytes [ 19 ].…”

“…Fernandes et al used autopsy specimens to study the different impact of immune cells in the pathogenesis of ( i ) fetuses with EFE and DCM; ( ii ) fetuses with secondary EFE (caused by outflow tract obstruction); and ( iii ) fetuses with normal hearts (control group) [ 19 ]. In their study, they excluded ( a ) syndromic cases; ( b ) intrauterine infection and/or maternal autoimmune history; ( c ) hypothyroidism; and ( d ) prenatal drug abuse.…”

“…The secondary fibroelastosis group had lower T-lymphocytes than the normal control group. These findings indicate either an initial shortage of immune cells in the myocardium, either their depletion [ 19 ]. In both situations, it seems that the myocardium is unable to fight against infections in the context of aggressive inflammatory process.…”