Biology subjects

Minns, D.

Publications and source records attributed to Minns, D..

3 recordsLinked to original sources

bioRxiv2020

The outcome of neutrophil-T cell contact differs depending on activation status of both cell types

Neutrophils and T cells exist in close proximity in lymph nodes and inflamed tissues during health and disease. They are able to form stable interactions, with profound effects on the phenotype and function of the T cells. However, the outcome of these effects are frequently contradictory; in some systems neutrophils suppress T cell proliferation, in others they are activatory or present antigen directly. Published protocols modelling these interactions in vitro do not reflect the full range of interactions found in vivo; they do not examine how activated and naive T cells differentially respond to neutrophils, or whether de-granulating or resting neutrophils induce different outcomes. Here, we established a culture protocol to ask these questions with human T cells and autologous neutrophils. We find that resting neutrophils suppress T cell proliferation, activation and cytokine production but that de-granulating neutrophils do not, and neutrophil released intracellular contents are pro-activatory. Strikingly, we also demonstrate that T cells early in the activation process are susceptible to suppression by neutrophils, while later-stage T cells are not, and naive T cells do not respond at all. Our protocol therefore allows nuanced analysis of the outcome of interaction of these cells and may explain contradictory results observed previously.

immunology↗

bioRxiv2020

Ultra-pure isolation of low density neutrophils casts doubt on their exceptionality in health and disease

Low density neutrophils (LDNs) are described in a number of inflammatory conditions, cancers and infections and associated with immunopathology, and a mechanistic role in disease. The role of LDNs at homeostasis in healthy individuals has not been investigated. We have developed an isolation protocol that generates high purity LDNs from healthy donors. Healthy LDNs were identical to healthy NDNs, aside from reduced neutrophil extracellular trap formation. CD66b, CD16, CD15, CD10, CD54, CD62L, CXCR2, CD47 and CD11b were expressed at equivalent levels in LDNs and normal density neutrophils (NDNs) and underwent apoptosis and ROS production interchangeably. Healthy LDNs had no differential effect on CD4+ or CD8+ T cell proliferation or IFN{gamma} production compared with NDNs. LDNs were generated from healthy NDNs in vitro by activation with TNF, LPS or fMLF, suggesting a mechanism of LDN generation in disease however, we show neutrophilia in people with Cystic Fibrosis (CF) was not due to increased LDNs. LDNs are present in the neutrophil pool at homeostasis and have limited functional differences to NDNs. We conclude that increased LDN numbers in disease reflect the specific pathology or inflammatory environment and that neutrophil density alone is inadequate to classify discrete functional populations of neutrophils. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/156588v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@1d10e01org.highwire.dtl.DTLVardef@1ee6bc3org.highwire.dtl.DTLVardef@1e5037dorg.highwire.dtl.DTLVardef@480797_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2020

The neutrophil antimicrobial peptide cathelicidin promotes Th17 differentiation

The host defence peptide cathelicidin (LL-37 in humans, mCRAMP in mice) is released from neutrophils by de-granulation, NETosis and necrotic cell death; it has potent antibacterial, antiviral and antifungal activity as well as being a powerful immunomodulator. It is released in proximity to CD4+ T cells during inflammatory and infectious disease but its impact on T cell phenotype is scarcely understood. Here we demonstrate that cathelicidin is a powerful Th17 potentiating factor which increases expression of the aryl hydrocarbon receptor (AHR) and the ROR{gamma}t transcription factor, in a TGF-{beta}1-dependent manner. We show that cathelicidin induces IL-17F production in particular, and that its induction of IL-17A+F+ double producing cells is dependent on AHR while its induction of IL-17F single producing cells is not. In the presence of TGF-{beta}1, cathelicidin profoundly suppressed IL-2 and down-regulated T-bet, specifically directing T cells away from Th1 and into a Th17 phenotype. Strikingly, Th17, but not Th1 cells were protected from apoptotic death by cathelicidin, in the first example of a neutrophil-released mediator inducing survival of a T cell subset. Finally, we show that cathelicidin is released by neutrophils in mouse lymph nodes following inoculation of heat-killed Salmonella typhimurium and that cathelicidin-deficient mice have suppressed Th17 responses during inflammation, but not at steady state. We propose that the release of cathelicidin by neutrophils is required for maximal Th17 differentiation and IL-17 production by CD4+ T cells, and that this is one method by which early neutrophilia directs subsequent adaptive immune responses with some sophistication.

immunology↗