Burton, A. R. | Search bioRxiv

bioRxiv2022

Determining distinct roles of IL-1α through generation of an IL-1α knockout mouse with no defect in IL-1β expression

Interleukin 1 (IL-1) and IL-1{beta} are the founding members of the IL-1 cytokine family, and these innate immune inflammatory mediators are critically important in health and disease. Early studies on these molecules suggested that their expression was interdependent, with an initial genetic model of IL-1 depletion, the IL-1 KO mouse (Il1a-KOline1), showing reduced IL-1{beta} expression. However, studies using this line in models of infection and inflammation resulted in contrasting observations. To overcome the limitations of this genetic model, we have generated and characterized a new line of IL-1 KO mice (Il1a-KOline2) using CRISPR-Cas9 technology. In contrast to cells from the Il1a-KOline1, where IL-1{beta} expression was drastically reduced, bone marrow-derived macrophages (BMDMs) from Il1a-KOline2 mice showed normal induction and activation of IL-1{beta}. Additionally, Il1a-KOline2 BMDMs showed normal inflammasome activation and IL-1{beta} expression in response to multiple innate immune triggers, including both pathogen-associated molecular patterns and pathogens. Moreover, using Il1a-KOline2 cells, we confirmed that IL-1, independent of IL-1{beta}, is critical for the expression of the neutrophil chemoattractant KC/CXCL1. Overall, we report the generation of a new line of IL-1 KO mice and confirm functions for IL-1 independent of IL-1{beta}. Future studies on the unique functions of IL-1 and IL-1{beta} using these mice will be critical to identify new roles for these molecules in health and disease and develop therapeutic strategies.

cell biology↗

bioRxiv2021

SARS-CoV-2-specific memory B cells can persist in the elderly despite loss of neutralising antibodies

Memory B cells (MBC) can provide a recall response able to supplement waning antibodies with an affinity-matured response better able to neutralise variant viruses. We studied a cohort of vulnerable elderly care home residents and younger staff, a high proportion of whom had lost neutralising antibodies (nAb), to investigate their reserve immunity from SARS-CoV-2-specific MBC. Class-switched spike and RBD-tetramer-binding MBC with a classical phenotype persisted five months post-mild/asymptomatic SARS-CoV-2 infection, irrespective of age. Spike/RBD-specific MBC remained detectable in the majority who had lost nAb, although at lower frequencies and with a reduced IgG/IgA isotype ratio. Functional spike/S1/RBD-specific recall was also detectable by ELISpot in some who had lost nAb, but was significantly impaired in the elderly, particularly to RBD. Our findings demonstrate persistence of SARS-CoV-2-specific MBC beyond loss of nAb, but highlight the need for careful monitoring of functional defects in RBD-specific B cell immunity in the elderly. One sentence summaryCirculating class-switched spike and RBD-specific memory B cells can outlast detectable neutralising antibodies but are functionally constrained in the elderly.

immunology↗