Hering, D. | bioRxiv Science

bioRxiv2022

Effects of woody riparian vegetation on macroinvertebratesare context-specific and large in urban and especiallyagricultural landscapes

O_LIWoody riparian vegetation (WRV) benefits benthic macroinvertebrates. However, in recent large scale studies, the effects of WRV on macroinvertebrates were small compared to catchment landuse, raising the question about the relevance of WRV in restoration. Limited effects of WRV might be due to context specificity: While some functions are provided by WRV irrespective of catchment landuse, others depend on the landscape setting. C_LIO_LIRecursive partitioning modelling was used to identify context dependent effects of WRV on streams macroinvertebrates ecological status in small lowland (n = 361) and mountain streams (n = 748). WRV cover was quantified from orthophotos along the near (500 m) and far (5,000 m) upstream river network and used to predict the sites ecological status. Agricultural, urban and woodland cover at the local and catchment scales along with hydromorphology were considered as partitioning variables. C_LIO_LIIn rural agricultural landscapes, the effect of WRV on the ecological status was large, indicating that establishing WRV can improve the ecological status by as much as two classes. C_LIO_LIIn streams impacted by catchment urbanization, effects of WRV were largest, but WRV cover and ecological status were both low, indicating practical limitations of WRV restoration in urban catchments. C_LIO_LISynthesis and applications: Independent effects of WRV on macroinvertebrates ecological status can be discerned from catchment landuse. While WRV can also improve the ecological status in urban settings, it is especially relevant for river management in rural agricultural catchments, where developing WRV potentially are effective measures to reach good ecological status C_LI

ecology↗

bioRxiv2021

GPR55 in B cells limits atherosclerosis development and regulates plasma cell maturation

Identifying novel pathways regulating the adaptive immune response in chronic inflammatory diseases such as atherosclerosis is of particular interest in view of developing new therapeutic drugs. Here we report that the lipid receptor GPR55 is highly expressed by splenic B cells and inversely correlates with atheroma plaque size in mice. In human carotid endarterectomy specimen, GPR55 transcript levels were significantly lower in unstable compared to stable carotid plaques. To study the impact of GPR55 deficiency in atherosclerosis, we crossed Gpr55 knockout mice with apolipoprotein E (ApoE) knockout mice and subjected the mice to Western diet for 4 to 16 weeks. Compared to ApoE-/- controls, ApoE-/-Gpr55-/- mice developed larger plaques with increased necrotic core size, associated with elevated circulating and aortic leukocyte counts. Flow cytometry, immunofluorescence and RNA-sequencing analysis of splenic B cells in these mice revealed a hyperactivated B cell phenotype with disturbed plasma cell maturation and immunoglobulin (Ig)G antibody overproduction. The specific contribution of B cell GPR55 in atherosclerosis was further studied in mixed Gpr55-/-/{micro}MT bone marrow chimeras on low density receptor deficiency (Ldlr-/-) background, revealing that B-cell specific depletion of Gpr55 was sufficient to promote plaque development. Conversely, adoptive transfer of wildtype B cells into ApoE-/-Gpr55-/- mice blunted the proatherogenic phenotype. In vitro stimulation of splenocytes with the endogenous GPR55 ligand LPI promoted plasma cell proliferation and enhanced B cell activation marker expression, which was inhibited by the GPR55 antagonist CID16020046. Collectively, these discoveries provide new evidence for GPR55 as key modulator of the adaptive immune response in atherosclerosis. Targeting GPR55 could be useful to limit inflammation and plaque progression in patients suffering from atherosclerosis.

immunology↗