Download especially b-lymphocytes from patients with sjögren´s syndrome

Thema: 3 x 3 (3 Slides in 3 Minutes) Abstract Präsentationen - I
49.15
ESPECIALLY B-LYMPHOCYTES FROM PATIENTS WITH SJÖGREN´S SYNDROME SHOW A
DYSREGULATION IN THE GENE EXPRESSION OF COMPONENTS OF THE PROTEASOME
SYSTEM
Martinez Gamboa L.1, Lesemann K.1, Scheffler S.1, Kuckelkorn U.2, Egerer K.3, Dörner T.4, Burmester
G.4, Faustman D.5, Feist E.4
(1) Charite Universitätsmedizin Berlin / Rheumatologie u. Klinische Immunologie, Forschungslabor AG Dr.
Eugen Feist, Berlin, (2) Charite Universitätsmedizin Berlin, Institut für Biochemie, Berlin, (3) Charite
Universitätsmedizin Berlin / Rheumatologie u. Klinische Immunologie, Rheumatologisches Labor, Berlin, (4)
Charité Universitätsmedizin Berlin - Campus Mitte, Med. Klinik III, Schwerpunkt Rheumatologie und Klin.
Immunologie, Berlin, (5) Harvard Medical School/Massachusetts General Hospital, Immunobiology
Laboratory, Charlestown
Zielsetzung
Some components of the proteasome system has been shown to be dysregulated in total peripheral blood
mononuclear cells (PBMCs) from patients with primary Sjögren's syndrome (pSS), but it is not yet clear
which specific blood cell subsets are involved. Due to the central role of the proteasome for the immune
response through antigen processing/presentation and in apoptosis, elucidation of the involved cell subset(s)
in relation to the proteasome alteration could be important for understanding disease pathogenesis.
Therefore, we compared gene expression of constitutive and inducible catalytic subunits of the 20S
proteasome in isolated blood immune competent cellular subsets. Additional investigations in vitro included
analysis of proteasome activity and of apoptosis after exposure to the proteasome inhibitor Bortezomib.
Methodik
CD4+ and CD8+ T-lymphocytes, CD19+ B-lymphocytes, CD14+ monocytes and total dendritic cells were
sorted from peripheral blood samples of patients and controls. Transcript levels of proteasome system
components, including the constitutive catalytic subunits Delta, Z and MB1, and their corresponding inducible
ones LMP2, MECL and LMP7, were relative quantified by real time PCR.
After proteasome inhibition in vitro, proteasome activity was measured based on hydrolysis of the fluorogenic
substrate Suc-LLVY-AMC, and apoptosis was assessed based on the activity of caspase-3 and -7.
For statistic analysis, Mann-Whitney test and P-values <0.005 were applied.
Ergebnisse
Especially B-lymphocytes from pSS showed a marked activation of the proteasome system, with significant
up-regulation of all constitutive and inducible subunits. Apart from B-cells, transcript levels of LMP7 were
also highly increased in CD8+ T-cells and in monocytes from patients, reflecting the systemic autoimmune
process. Preliminary data from further in vitro studies confirm the dysregulation of the proteasome in B-cells:
after exposition to Bortezomib, proteasome activity is reduced in a similar degree in PBMCs and Tlymphocytes, but to a lesser extent in B-lymphocytes, and apoptosis is stronger induced in total PBMCs and
T-cells than in B-cells.
Schlussfolgerung
Our results show that the proteasome system is strongly activated specially in B-lymphocytes from patients
with Sjögren's syndrome. According to our preliminary data, B-cells seem to be more resistant to the effects
of proteasome inhibition with Bortezomib than other cell subsets. These results should encourage further
investigations in the field of proteasome inhibition in patients with Sjögren's syndrome.