Biology subjects

Nierkens, S.

Publications and source records attributed to Nierkens, S..

2 recordsLinked to original sources

bioRxiv2022

Soluble signal inhibitory receptor on leukocytes-1 is released from activated neutrophils by proteinase 3 cleavage

Signal inhibitory receptor on leukocytes-1 (SIRL-1) is an immune inhibitory receptor expressed on human granulocytes and monocytes which dampens antimicrobial functions. We previously showed that sputum neutrophils from infants with severe respiratory syncytial virus (RSV) bronchiolitis have decreased SIRL-1 surface expression compared to blood neutrophils, and that SIRL-1 surface expression is rapidly lost from in vitro activated neutrophils. This led us to hypothesize that activated neutrophils lose SIRL-1 by ectodomain shedding. Here, we developed an ELISA and measured the concentration of soluble SIRL-1 (sSIRL-1) in RSV bronchiolitis and hospitalized COVID-19 patients, which are both characterized by neutrophilic inflammation. In line with our hypothesis, sSIRL-1 concentration was increased in sputum compared to plasma of RSV bronchiolitis patients, and in serum of hospitalized COVID-19 patients compared to control serum. In addition, we show that in vitro activated neutrophils release sSIRL-1 by proteolytic cleavage, which can be prevented by proteinase 3 inhibition. Finally, we found that SIRL-1 shedding is prevented by extracellular adherence protein (Eap) from S. aureus. Notably, we recently showed that SIRL-1 is activated by PSM3 from S. aureus, suggesting that S. aureus may counteract SIRL-1 shedding to benefit from preserved inhibitory function of SIRL-1. In conclusion, we are the first to report that SIRL-1 is released from activated neutrophils by proteinase 3 cleavage and that endogenous sSIRL-1 protein is present in vivo.

immunology↗

bioRxiv2022

Functional Specialization of Specific DC Subsets in the Synovial Fluid of JIA Patients

Dendritic cells (DC) are crucial for initiating and shaping immune responses. So far, little is known about heterogeneity and functional specialization of human DC subsets in (local) inflammatory conditions. We profiled conventional (c)DC1, cDC2 and monocytes based on phenotype, transcriptome and function from a local inflammatory site, namely synovial fluid (SF) from patients suffering from a chronic inflammatory condition, Juvenile Idiopathic Arthritis (JIA). cDC1, a relatively small dendritic cell subset in blood, are strongly enriched in SF. SF cDC1 showed a quiescent immune signature without a clear inflammatory profile low expression of PRR, chemokine, and cytokine receptors, and poor induction of T cell proliferation and cytokine production, but selective production of IFN{lambda} upon polyinosinic:polycytidylic acid exposure. In stark contrast, cDC2 and monocytes from the same environment, showed a pro-inflammatory transcriptional profile, high levels of (spontaneous) pro-inflammatory cytokine production, and strong induction of T cell proliferation and cytokine production, including IL-17. Although the cDC2 and monocytes showed an overlapping transcriptional core profile, there were clear differences in the transcriptional landscape and functional features, indicating that these cell types retain their lineage identity in chronic inflammatory conditions. In conclusion, our findings suggest that at the site of inflammation, there is specific functional programming of human DC subsets, especially cDC2. In contrast, the enriched subset of cDC1 remains relatively quiescent and seemingly unchanged under inflammatory conditions, pointing to a more regulatory role.

immunology↗