Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.

Plasma Endogenous Met- and Leu-Enkephalin Levels Are Decreased and Associated with Clinical and Laboratory Parameters in Early Systemic Sclerosis.

McNearney4,  Terry A., Sluka2,  Kathleen A., Ahn5,  Chul W., Reveille6,  John D., Fischbach1,  Michael, Mayes3,  Maureen D.

Univ Texas Hlth Sci Ctr at San Antonio, San Antonio, TX
University of Iowa Medical Center, Iowa City, IA
University of Texas -Houston Health Sciences Center, Houston, TX
University of Texas Medical Branch, Galveston, TX
University of Texas Southwestern Medical Center, Dallas, TX
University of Texas-Houston Health Sciences Center, Houston, TX


Met-and leu-enkephalins are endogenous opioid neuropeptides with potent analgesic, vasoactive, immunomodulatory and anti-apoptotic properties. Endogenous enkephalin levels demonstrate modest effects on vascular patency under normal physiologic conditions in the brain, but have appreciable influence under periods of traumatic or anoxic stress. We hypothesized that clinical or immunological variables of early systemic sclerosis (SSc) might be correlated to plasma enkephalin levels.


Plasma samples were collected at study entry of the Genetics versus Environment in Scleroderma Outcomes Study (GENISOS) cohort (early SSc, N=136). Plasma met-enkephalin and leu-enkephalin levels (ug/ml) were measured by high performance liquid chromatography (HPLC) and correlated to clinical and laboratory parameters in the GENISOS database. Statistical analyses were performed by nonparametric Wilcoxon rank sum tests and Pearson correlation coefficients.


1. SSc patient vs matched normal controls study: SSc patients had significantly lower plasma met-enkephalin levels (0.16±0.10 vs 0.28±0.14 mg/ml, p=0.05) and lower plasma leu-enkephalin levels (1.04±0.90 vs 2.45±0.10 mg/ml, respectively, p<0.03); 2. Significantly lower plasma met-enkephalin levels were associated with anti-topoisomerase-I seropositivity (6±8.3 vs 14.9±22.8 ug/ml, p=0.02). 3. Plasma leu-enkephalin levels were significantly higher in SSc patients with digital pulp loss (95.6±130 vs 64.9±101 ug/ml, p=0.03). Lower mean plasma met-enkephalin levels and inversely higher leu-enkephalin levels were noted in SSc patients with Raynaud's phenomena (p=NS). Plasma endogenous enkephalin levels were independent of seasonal temperatures, when analyzed by month or season (p=NS).


Lower plasma levels of endogenous enkephalins in small SSc vs matched control groups may reflect depressed synthesis or increased degradation related to ongoing neurogenic, vasogenic or fibrogenic processes. The associations of plasma enkephalin levels to immunologic or clinical pathologies in early SSc may underscore their vasogenic or fibrogenic significance and potential as therapeutic targets.

To cite this abstract, please use the following information:
McNearney, Terry A., Sluka, Kathleen A., Ahn, Chul W., Reveille, John D., Fischbach, Michael, Mayes, Maureen D.; Plasma Endogenous Met- and Leu-Enkephalin Levels Are Decreased and Associated with Clinical and Laboratory Parameters in Early Systemic Sclerosis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1226
DOI: 10.1002/art.28992

Abstract Supplement

Meeting Menu