Firestormm
Senior Member
- Messages
- 5,055
- Location
- Cornwall England
Via Tate Mitchel and Co-cure
@Legendrew thought you might be interested as well as others.
26 February 2014
Autoimmune Basis for Postural Tachycardia Syndrome
Hongliang Li, MD, PhD;Xichun Yu, MD;Campbell Liles, BS;Muneer Khan, MD; Megan Vanderlinde‐Wood, MD;Allison Galloway, MD;Caitlin Zillner, BS;Alexandria Benbrook, BS; Sean Reim, BS;Daniel Collier, BS;Michael A. Hill, PhD;Satish R. Raj, MD;Luis E. Okamoto, MD; Madeleine W. Cunningham, PhD;Christopher E. Aston, PhD;David C. Kem, MD
Background
Patients with postural tachycardia syndrome (POTS) have exaggerated orthostatic tachycardia often following a viral illness, suggesting autoimmunity may play a pathophysiological role in POTS. We tested the hypothesis that they harbor functional autoantibodies to adrenergic receptors (AR).
Methods and Results
Fourteen POTS patients (7 each from 2 institutions) and 10 healthy subjects were examined for α1AR autoantibody‐mediated contractility using a perfused rat cremaster arteriole assay.
A receptor‐transfected cell‐based assay was used to detect the presence of β1AR and β2AR autoantibodies. Data were normalized and expressed as a percentage of baseline.
The sera of all 14 POTS patients demonstrated significant arteriolar contractile activity (69±3% compared to 91±1% of baseline for healthy controls, P<0.001) when coexisting β2AR dilative activity was blocked; and this was suppressed by α1AR blockade with prazosin.
POTS sera acted as a partial α1AR antagonist significantly shifting phenylephrine contractility curves to the right. All POTS sera increased β1AR activation (130±3% of baseline, P<0.01) and a subset had increased β2AR activity versus healthy subjects.
POTS sera shifted isoproterenol cAMP response curves to the left, consistent with enhanced β1AR and β2AR agonist activity. Autoantibody‐positive POTS sera demonstrated specific binding to β1AR, β2AR, and α1AR in transfected cells.
Conclusions
POTS patients have elevated α1AR autoantibodies exerting a partial peripheral antagonist effect resulting in a compensatory sympathoneural activation of α1AR for vasoconstriction and concurrent βAR‐mediated tachycardia.
Coexisting β1AR and β2AR agonistic autoantibodies facilitate this tachycardia. These findings may explain the increased standing plasma norepinephrine and excessive tachycardia observed in many POTS patients.
New evidence of autoimmunity in POTS!
February 25, 2014 autoimmune, POTS, research
IS POTS AN AUTOIMMUNE DISEASE?
Big news this week in POTS research! Researchers from the University of Oklahoma and Vanderbilt University have identified evidence of adrenergic receptor autoantibodies in a small group of POTS patients, suggesting that POTS may be an autoimmune condition in these patients. The study was published in the Journal of the American Heart Association (JAHA). JAHA is an official journal of the American Heart Association, so this is great news for POTS awareness!
To help patients better understand what this means, Dr. David Kem from the University of Oklahoma Health Sciences Center has kindly provided Dysautonomia International with a patient friendly explanation of this complex research. Before we get to Dr. Kem’s explanation, let’s go over the basics of adrenergic receptors and autoantibodies...
Read blog...
@Legendrew thought you might be interested as well as others.