Involvement of protein kinase C in C5a-primed neutrophils for ANCA-mediated activation

C5a and the neutrophil C5a receptor play a central role in antineutrophil cytoplasmic antibody (ANCA)-mediated neutrophil recruitment and activation. Our recent study found that activation of p38 mitogen-activated protein kinase (p38MAPK), extracellular signal-regulated kinase (ERK) and phosphoinositol 3-kinase (PI3 K) are all important steps in the translocation of ANCA antigens by C5a-mediated priming and activation of neutrophils. The current study further investigated the protein kinase C (PKC) pathway of C5a-mediated neutrophils for ANCA-induced activation.The effect of the PKC inhibitor (bisindolylmaleimide I, BIS) was tested on respiratory burst and degranulation of C5a-primed neutrophils activated with ANCA, as well as on C5a-induced increase in expression of PR3 and MPO.For C5a-primed neutrophils for MPO-ANCA-induced respiratory burst, the mean fluorescence intensity (MFI) value was 369.8 ± 18.8, which decreased to 308.3 ± 14.2 upon pre-incubation with BIS (P < 0.001). For PR3-ANCA-positive IgG, the MFI value increased in C5a-primed neutrophils, which decreased upon pre-incubation with BIS. The lactoferrin concentration increased from 414.8 ± 26.9 ng/ml in the non-primed neutrophils supernatant to 1099.8 ± 80.7 ng/ml in C5a-primed neutrophils induced by MPO-ANCA-positive IgG supernatant (P < 0.001), and decreased to 814.5 ± 45.3 ng/ml upon pre-incubation with BIS (P < 0.01). The lactoferrin concentration also increased in C5a-primed neutrophils induced by PR3-ANCA-positive IgG supernatant and decreased upon pre-incubation with BIS. Membrane expression of PR3 (mPR3) expression increased from 788.0 ± 87.5 in untreated cells to 1071.3 ± 81.3 after C5a treatment and decreased to 827.3 ± 48.1 by BIS (P < 0.05).Activation of PKC is an important step in the translocation of ANCA antigens and C5a-induced activation of neutrophils by ANCA.

► PKC involved in the membrane expression of PR3 by C5a-mediated priming. ► PKC inhibitor decreased MPO concentration in C5a-primed neutrophils supernatant. ► PKC involved in C5a-primed neutrophils for ANCA-induced respiratory burst.