INCREASED EXPRESSION OF pERK AND pJNK KINASES IN PERIPHERAL BLOOD MONONUCLEAR CELLS REFLECTS DISEASE ACTIVITY IN SYSTEMIC LUPUS ERYTHEMATOSUS PATIENTS
Bloch O. 1, Molad Y. 5 , Yona E. 3 , Amit M. 4, Rapoport M.J. 1,2
Diabetes Research Laboratory,2Department C of Internal Medicine, 3Day Hospital and
4Rheumatology Departments, Assaf Harofeh Medical Center,
and 5Rheumatology Department, Rabin Medical Center,
both affiliated to Sackler Faculty of Medicine,
Tel-Aviv University, Israel
Background
It was demonstrated previously that aberrant signaling of the p21RAS /MAP kinase pathway reflects disease activity in systemic lupus erythematosis (SLE) patients ( Rapoport MJ et al 1999,2002). In addition, up-regulated activity of JNK kinase in lymphocytes of (NZBxNZW)F1 mice which manifest SLE -like disease is normalized following curative treatment ( Rapoport MJ et al, 2005).
Aim
The aim of this study was to investigate whether expression and activity of the MAP kinases ERK and JNK reflect disease activity in SLE patients.
Patients and methods
Forty-two SLE patients (36 females and 6 males) were recruited from 2 Israeli hospital rheumatology outpatient clinics: Assaf Harofeh Medical Center and Rabin Medical Center. The patients had a mean age of 44.312.75 (range 25 to 79) and mean disease duration was 14.1 1.74 years. Patients were observed during routine consecutive 3-4 visits in the outpatient clinics. During each visit Disease activity was assessed using the SLE Disease Activity Index (SLEDAI) and whole blood was drawn and sent immediately to a central laboratory. Mean study duration from first to last visit was 13.4 0.83 months and mean interval between visits was 4.9 0.33 months. SLE patients with inactive disease were defined as SLEDAI score of 0 - 3 points and patients with active disease as a score of 4 – 20 SLEDAI points. The later group was divided on mild SLE ( SLEDAI 4 to 6 points) and moderate/severe SLE ( SLEDAI 7 to 20 points). The SELENA-SLEDAI modification score was used to assess changes in disease activity: an increase in SLEDAI ≥3 points was defined as mild or moderate flare and SLEDAI increase ≥12 as severe flare. Control group included samples of 20 healthy subjects. Expression of inactive (ERK, JNK) and phosphorylated active forms (pERK and pJNK) were determined in whole protein lysates of peripheral blood mononuclear cells by Western Blot analysis and quantified by computing densitometry.
Results
The mean levels of active pERK and pJNK kinases were significantly increased in active disease patients as compared with inactive SLE patients p=0.03 and p= 0.04 respectively and when compared to healthy controls (p=0.03 and p=0.003). Meanwhile, the mean expression of the inactive forms of ERK and JNK, remained unchanged in active and non active SLE patients. pERK/ERK ratio was increased in active SLE (1:1) versus healthy patients (1:2) as well as pJNK/JNK ratio which was higher in active SLE ( 1:2 ) compared with control (1:3).
Conclusions:
These results demonstrate that ERK/JNK kinase activity reflects SLE disease activity in human patients. These MAP kinases may serve as potential biomarkers or future therapeutic targets.
