Altered neutrophil G-protein receptor signalling linked to impaired chemotaxis and increased ROS and NET production in older people with frailty

BackgroundImmune function alters with age, and is often accompanied by chronic, low-grade inflammation (inflammageing). In individuals with frailty, inflammageing is increased, reducing immune function and increasing susceptibility to serious outcomes from infection. In this study we investigated the changes that take place in human neutrophils during healthy ageing and ageing with frailty (FR) using RNAseq and functional assays. We also compared neutrophil phenotype in frailty with rheumatoid arthritis (RA) neutrophils. MethodsBlood neutrophil RNAseq data were analysed using IDEP2 and Ingenuity Pathway Analysis (IPA). Neutrophil phenotype was assessed for reactive oxygen species (ROS) production, neutrophil extracellular trap (NET) release, chemotaxis, and bacterial killing capacity. Experimental data were analysed by ANOVA in R (v4.5.1). ResultsRNAseq identified activation of G-protein coupled receptors, interferon and cytokine receptor signalling, and chemotaxis pathways in frail individuals (n=10) compared to healthy older (n=9) and healthy younger people (n=8, adj. p<0.05). FR neutrophils expressed more IL-8 receptors (CXCL1 and CXCL2) and CD177 on their surface (p<0.05). FR neutrophil phenotype was similar to RA, with significantly higher ROS production and impaired chemotaxis and bacterial killing capacity (p<0.05). FR neutrophils also released significantly more NETs in response to LPS (10ng/mL, p<0.05). ConclusionsThis work provides novel insight into the changes to neutrophil phenotype associated with ageing in good health and ageing with frailty, and highlights similarities between inflammageing in frailty and chronic inflammation in RA. This may be important in the development of future therapeutics and/or health management strategies to support healthy living as we age. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=148 HEIGHT=200 SRC="FIGDIR/small/25342352v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@15decc0org.highwire.dtl.DTLVardef@1627086org.highwire.dtl.DTLVardef@1c9982eorg.highwire.dtl.DTLVardef@262730_HPS_FORMAT_FIGEXP M_FIG In this study we have combined RNAseq with functional experiments to describe the phenotype of neutrophils from people with frailty. We found that frailty neutrophils had altered gene expression with activation of G-protein coupled receptors, interferon and cytokine receptor signalling, and chemotaxis pathways. This was associated with altered ROS and NET production, impaired chemotaxis and impaired bacterial killing capacity compared to healthy older neutrophils. Created in BioRender. Abdullah, G. (2026) https://BioRender.com/ze634lt and https://BioRender.com/7khpj2z. C_FIG