Altered iron metabolism in lymphocytes from subjects with restless legs syndrome.
OBJECTIVE
Studies using cerebrospinal fluid, magnetic resonance imaging, and autopsy tissue have implicated a primary role for brain iron insufficiency in restless legs syndrome (RLS). If the abnormalities of brain iron regulation reflect a basic disturbance of iron metabolism, then this might be expressed at least partially in some peripheral systems. Thus the study aim was to determine whether patients with RLS and control subjects show differences in lymphocyte iron regulator proteins.


METHODS
Fasting morning blood samples were used to obtain common serum measures of iron status and to determine lymphocyte iron management proteins. Twenty-four women with early-onset RLS and 25 control women without RLS symptoms were studied.


RESULTS
RLS and control subjects were matched for age, hemoglobin, and serum iron profile. However, transferrin receptor (TfR) and DMT1 (divalent metal transporter 1 protein) levels in lymphocytes were significantly higher for RLS patients than for controls. No significant differences in ferritin subtypes or transferrin levels were found. No significant correlations were found between lymphocyte and serum indices of iron status.


CONCLUSIONS
RLS lymphocytes showed an increase in ferroportin, implying increased cellular iron excretion, in the face of increased iron need (increased TfR and DMT1). In the absence of changes in H-ferritin, the findings indicate a balance between input and output with no net iron change but probable overall increase in iron turnover. The lack of any significant correlation between serum and lymphocyte iron indices indicates that iron management proteins from lymphocytes are at a minimum an alternative and independent marker of cellular iron metabolism.
Department of Neurology, Johns Hopkins University, Baltimore, MD, USA. cearley@jhmi.edu
Christopher J
CJ
Earley
Padmavathi
P
Ponnuru
Xinsheng
X
Wang
Stephanie M
SM
Patton
James R
JR
Conner
John L
JL
Beard
Dennis D
DD
Taub
Richard P
RP
Allen
D000328:Adult; D027682:Cation Transport Proteins / Q000097:blood*; D005260:Female; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D007501:Iron / Q000378:metabolism*; D008214:Lymphocytes / Q000378:metabolism*; D008875:Middle Aged; D011990:Receptors, Transferrin / Q000378:metabolism*; D012148:Restless Legs Syndrome / Q000378:metabolism* / Q000503:physiopathology*; D000099236:Solute Carrier Family 11, Member 2
D027682:Cation Transport Proteins; D006454:Hemoglobins; D007501:Iron; D011990:Receptors, Transferrin; D000099236:Solute Carrier Family 11, Member 2