Induction of neutrophil-derived reactive oxygen species and neutrophil extracellular trap generation by calcium pyrophosphate dihydrate crystals.

MARÍA BELÉN LUFFI; RODRIGO BLAS; VICTORIA BORGIA; MARCOS BORGIA; IVÁN BORGIA; ALFREDO BORGIA; MARÍA CRISTINA PISTORESI; MARÍA SILVIA DI GENARO; CAROLINA GORLINO

Mar del Plata

Congreso; Reunión Conjunta SAIC SAI&FAIC SAFIS 2022; 2022

Sociedades científicas SAIC, SAI&FAIC, SAFIS

Deposition of calcium pyrophosphate dihydrate (CPP) crystals injoints and soft tissues is the cause of acute or chronic inflammatory responses known as Calcium Pyrophosphate Crystal DepositionDisease (CPPD). Cell activation by CPP crystals is a central featureand pro-inflammatory crystals can interact with all of the major synovial cell types, including neutrophils. Although the neutrophil is amajor inflammatory cell type found in inflamed joints of acute CPPDpatients, little is known about interactions of neutrophils with CPPcrystals. In this study, we aimed at studying whether CPP crystalsinduce a pro-inflammatory profile in neutrophils, measured by degranulation, induction of reactive oxygen species (ROS) and neutrophil extracellular trap (NET) generation. Neutrophils were isolatedfrom healthy subjects and incubated with synthesized CPP crystals(CPP) or with synovial fluid from CPPD patients (CPPD-SF). Degranulation (measured by the expression of CD66b), ROS production (determined by DHR-123 assay) and NET formation (detectedby Sytox Green fluorescence) was studied by flow cytometry in basal neutrophils (control), neutrophils stimulated with synthesized CPPcrystals (CPP) or with CPPD-SF. P value is the result of one-wayANOVA (Kruskal-Wallis test) followed by Dunn’s post-hoc test orMann-Whitney test, when appropriate. We found that the presenceof CPP crystals in SF from CPPD patients induced extracellular DNAexposure in neutrophils (%SYTOX-Green positive cells, control vsCPPD-SF; p=0.03) as well as an up-regulation of CD66b expression (p=0.03). Moreover, CPPD-SF samples significantly increasedrespiratory burst in neutrophils (control vs CPPD-SF, p=0.04). Inconclusion, these data suggest that the presence of CPP crystals inSF from CPPD patients could have a role in the amplification of theinflammatory response by stimulating up-regulation of CD66b, NETrelease and ROS production in neutrophils