Chronic kidney disease leads to microglial potassium efflux and inflammasome activation in the brain.

Cognitive impairment is common in extracerebral diseases such as chronic kidney disease (CKD). Kidney transplantation reverses cognitive impairment, indicating that cognitive impairment driven by CKD is therapeutically amendable. However, we lack mechanistic insights allowing development of targeted therapies. Using a combination of mouse models (including mice with neuron-specific IL-1R1 deficiency), single cell analyses (single nuclei RNA sequencing and single cell thallium autometallography), human samples and in vitro experiments we demonstrate that microglia activation impairs neuronal potassium homeostasis and cognition in CKD. CKD disrupts the barrier of brain endothelial cells in vitro and the blood-brain barrier in vivo, establishing that the uremic state modifies vascular permeability in the brain. Exposure to uremic conditions impairs calcium homeostasis in microglia, enhances microglial potassium efflux via the calcium-dependent channel KCa3.1, and induces p38-MAPK associated IL-1ß maturation in microglia. Restoring potassium homeostasis in microglia using a KCa3.1-specific inhibitor (TRAM34) improves CKD-triggered cognitive impairment. Likewise, inhibition of the IL-1ß receptor 1 (IL-R1) using anakinra or genetically abolishing neuronal IL-1R1 expression in neurons prevent CKD-mediated reduced neuronal potassium turnover and CKD-induced impaired cognition. Accordingly, in CKD mice, impaired cognition can be ameliorated by either preventing microglia activation or inhibiting IL-1R-signaling in neurons. Thus, our data suggest that potassium efflux from microglia triggers their activation, which promotes microglia IL-1ß release and IL-1R1-mediated neuronal dysfunction in CKD. Hence, our study provides new mechanistic insight into cognitive impairment in association with CKD and identifies possible new therapeutic approaches.

LMWH prevents thrombo-inflammation in the placenta via HBEGF-AKT signalling.

Low molecular weight heparins (LMWH) are used to prevent or treat thromboembolic events during pregnancy. While studies suggest an overall protective effect of LMWH in preeclampsia (PE), their use in preeclampsia remains controversial. LMWH may convey beneficial effects in preeclampsia independent of their anti-coagulant activity, possibly by inhibiting inflammation. Here we evaluated whether LMWH inhibit placental thrombo-inflammation and trophoblast NLRP3 inflammasome activation. Using an established procoagulant extracellular vesicle (EV)-induced and platelet-dependent preeclampsia-like mouse model, we show that LMWH reduces pregnancy loss and trophoblast inflammasome activation, restores altered trophoblast differentiation and improves trophoblast proliferation in-vivo and in-vitro. Moreover, LMWH inhibits platelet independent trophoblast NLRP3 inflammasome activation. Mechanistically, LWMH activates via Heparin binding epidermal growth factor (HBEGF) signaling the PI3-Kinase-AKT pathway in trophoblasts thus preventing inflammasome activation. In human preeclampsia placental explants, inflammasome activation and PI3-Kinase-AKT signaling events were reduced with LMWH treatment compared to those without LMWH treatment. Thus, LMWH inhibits sterile inflammation via the HBEGF signaling pathway in trophoblasts and ameliorates preeclampsia-associated complications. These findings suggest that drugs targeting the inflammasome may be evaluated in preeclampsia and identify a signaling mechanism through which LMWH ameliorates preeclampsia, thus providing a rationale for the use of LMWH in preeclampsia.

Tissue factor binds to and inhibits interferon-α receptor 1 signaling.

Tissue factor (TF), which is a member of the cytokine receptor family, promotes coagulation and coagulation-dependent inflammation. TF also exerts protective effects through unknown mechanisms. Here, we showed that TF bound to interferon-α receptor 1 (IFNAR1) and antagonized its signaling, preventing spontaneous sterile inflammation and maintaining immune homeostasis. Structural modeling and direct binding studies revealed binding of the TF C-terminal fibronectin III domain to IFNAR1, which restricted the expression of interferon-stimulated genes (ISGs). Podocyte-specific loss of TF in mice (PodΔF3) resulted in sterile renal inflammation, characterized by JAK/STAT signaling, proinflammatory cytokine expression, disrupted immune homeostasis, and glomerulopathy. Inhibiting IFNAR1 signaling or loss of Ifnar1 expression in podocytes attenuated these effects in PodΔF3 mice. As a heteromer, TF and IFNAR1 were both inactive, while dissociation of the TF-IFNAR1 heteromer promoted TF activity and IFNAR1 signaling. These data suggest that the TF-IFNAR1 heteromer is a molecular switch that controls thrombo-inflammation.