Plasma neuropeptide Y: a biomarker for symptom severity in chronic fatigue syndrome.

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Dolphin

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Free full text at: http://www.behavioralandbrainfunctions.com/content/6/1/76

Plasma neuropeptide Y: a biomarker for symptom severity in chronic fatigue syndrome.

Behav Brain Funct. 2010 Dec 29;6:76.

Fletcher MA, Rosenthal M, Antoni M, Ironson G, Zeng XR, Barnes Z, Harvey JM, Hurwitz B, Levis S, Broderick G, Klimas NG.

Department of Medicine, University of Miami Miller School of Medicine, 1600 NW 10th Ave, Miami, FL USA. mfletche@med.miami.edu.

Abstract
ABSTRACT:

BACKGROUND: Chronic fatigue syndrome (CFS) is a complex, multi-symptom illness with a multisystem pathogenesis involving alterations in the nervous, endocrine and immune systems.Abnormalities in stress responses have been identified as potential triggers or mediators of CFS symptoms. This study focused on the stress mediator neuropeptide Y (NPY). We hypothesized that NPY would be a useful biomarker for CFS.

METHODS: The CFS patients (n = 93) were from the Chronic Fatigue and Related Disorders Clinic at the University of Miami and met the 1994 case definition of Fukuda and colleagues. Healthy sedentary controls (n = 100)) were from NIH or VA funded studies. Another fatiguing, multi-symptom illness, Gulf War Illness (GWI), was also compared to CFS. We measured NPY in plasma using a radioimmunoassay (RIA). Psychometric measures, available for a subset of CFS patients included: Perceived Stress Scale, Profile of Mood States, ATQ Positive & Negative Self-Talk Scores, the COPE, the Beck Depression Inventory, Fatigue Symptom Inventory, Cognitive Capacity Screening Examination, Medical Outcomes Survey Short Form-36, and the Quality of Life Scale.

RESULTS: Plasma NPY was elevated in CFS subjects, compared to controls (p = .000) and to GWI cases (p = .000). Receiver operating characteristics (ROC) curve analyses indicated that the predictive ability of plasma NPY to distinguish CFS patients from healthy controls and from GWI was significantly better than chance alone. In 42 patients with CFS, plasma NPY had significant correlations (<0.05) with perceived stress, depression, anger/hostility, confusion, negative thoughts, positive thoughts, general health, and cognitive status. In each case the correlation (+ or -) was in the anticipated direction.

CONCLUSIONS: This study is the first in the CFS literature to report that plasma NPY is elevated compared to healthy controls and to a fatigued comparison group, GWI patients. The significant correlations of NPY with stress, negative mood, general health, depression and cognitive function strongly suggest that this peptide be considered as a biomarker to distinguish subsets of CFS.

PMID: 21190576 [PubMed - in process]
 

Dolphin

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It is interesting that they try to die this in with viruses (amongst other things):

Another consideration of interest regarding NPY and CFS is the possibility of chronic viral infection in some patients. Du, et al [64], recently described increased NPY expression in the central nervous system (CNS) of mice following infection with a neurovirulent polytropic retrovirus. This virus infects macrophages and microglial cells resulting in production of proinflammatory cytokines [65], including interleukin 1 alpha (IL-1α), IL-β, and Il-6 known to be elevated in CFS [19]. Viral triggers such as EBV and HHV6 have long been suspected of involvement in the onset and persistence of CFS [3,5,6]. Evidence of xenotropic murine leukemia virus - related virus (XMRV) in peripheral blood mononuclear cells (PBMCs) in the majority of CFS cases, but not controls, supported the viral infection hypothesis [11]. This report by Lombardi, et al was followed by 4 subsequent reports of failure to detect any murine leukemia virus (MLV)-related virus gene sequences in blood from CFS patients [12,14,66,67] and one report of MLV-like virus gag gene sequences, but not XMRV, in 86.5% CFS cases compared with only 6.8% of healthy volunteer blood donors [13].
I think if others had written it we wouldn't have heard about viruses.
 

Dolphin

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Presuming they looked at all eight SF-36 subscales (they appear to), the fact that SF-36 General Health, Emotional Well-being (presumably role emotional) and Social Functioning (along with the other scales from other instruments) doesn't feel me with confidence that this is a marker of severity, but maybe I'm missing something.

If they were wanting to look at symptom severity, it is also disappointing they didn't measure "symptoms" more directly (rather than moods, etc).

In this study, we found that the stress hormone, NPY, was statistically elevated in plasma from CFS cases compared to healthy controls - and to a group of patients with another fatiguing, multi-symptom illness, GWI. This later finding was unexpected. However, it might be explained by gender distribution, which was very different between CFS and GWI.
They have the data so it is a pity they don't give us a breakdown by gender to see if it could be an issue.
 
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