Congresos y reuniones científicas
Título:
AUTOANTIBODY LEVELS INFLUENCES THE NUMBER AND PHENOTYPE OF INFILTRATING NEUTROPHILS IN INFLAMED JOINTS OF PATIENTS WITH RHEUMATOID ARTHRITIS
Autor/es:
GORLINO, C; DIAZ‐GABUTTI, MS; DAVE, M; BLAS, R; MUNARRIZ A; TAMASHIRO, H; PARDO HIDALGO, RA; PISTORESI, MC; DI GENARO, S
Reunión:
Congreso; Congreso latinoamericano de Inmunología 2015; 2015
Resumen:
Rheumatoid arthritis (RA) manifests with persistent synovial inflammation, cellular infiltration
and proinflammatory
cytokine production, and results in progressive joint destruction.
Although the etiology and pathogenesis of RA are still unclear, there are many inflammatory
cells accumulated in the synovial fluid (SF) which are involved in the pathogenesis of RA. Of all
the cell types implicated in the pathology of RA, neutrophils are the most abundant cells present
either in the SF of the affected joints or at the pannus/cartilage interface. In RA, neutrophils are
commonly recruited into joints by chemoattractants and enhance tissue damage. Among the
numerous autoantibodies associated with RA, anticyclic
citrullinated peptide antibodies
(ACPA) are now recognized as the most diseasespecific
biomarker. Although the presence or
absence of autoantibodies in patients with RA can guide clinical practice, the specific role of
autoantibody status is unclear. The aim of this study was to investigate the association between
neutrophil infiltration into inflamed joints and the presence of ACPA in RA patients.
Synovial fluid (SF) samples were obtained from 65 patients who fullfilled
the American College
of Rheumatology/European League Against Rheumatism (ACR/EULAR) RA classification
criteria. All patients gave informed consent, and the protocol of the study was approved by the
ethic board from IBYME (CE 0032/
2013). Disease activity was evaluated by 28joint
count
Disease Activity Score (DAS28).
Immunoglobulin G (IgG) ACPA (CCP3) and interleukin (IL)8
levels were tested in SF samples using commercial ELISA kit; total IgG levels in SF were
determined by radial immunodiffusion assay. Flow cytometric analysis was used to assess
surface expression of CD16, CD62L, CXCR1 and CD54 on in vitrostimulated
neutrophils from
peripheral blood of healthy individuals and on SFneutrophils
from RA patients. Spearman test
was performed to identify correlations. A p value less than 0.05 was considered as statistically
significant.
We found that in the presence of ACPA autoantibodies (ACPApositive
patients), the number of
neutrophils infiltrating inflamed joints correlated with severe disease activity (p=0.014). This
was not the case for ACPAnegative
patients (p=0.31). Additionally, in ACPApositive
patients,
neutrophil counts correlated positively with IL8
levels (p=0.04) and higher levels of this
cytokine were related with worse clinical manifestations (r=0.3; p=0.04). We also demonstrated
that the ratio of ACPA/total IgG in SF was positively correlated with disease activity (p=0.03).
For this reason, we decided to investigate the effect of the presence of ACPA autoantibodies on
neutrophil phenotype by flow cytometry. Upon in vitrostimulation
of peripheral bloodneutrophils
with SF, we showed that a subset of CD16highCD62Llow neutrophils appeared and
that the percentage of these cells was higher after stimulation with SF from RA patients with
higher ACPA/total IgG ratio. When we analyzed neutrophils from SF of RA patients, we found
that this subset of CD16highCD62Llow neutrophils was also related with ACPA/total IgG ratio and that these cells showed decreased levels of CXCR1 marker and an increased expression of
CD54.
Our study provides a novel evidence of the relationship among the presence of ACPA antibodies
with disease activity and with the numbers of infiltrating neutrophils and their phenotype in
inflamed joints of RA patients. Our results suggest that ACPA levels may modulate neutrophil
activity and thus contributing with joint inflammation in RA patients.