Zindel, J. | Search bioRxiv

bioRxiv2021

Single cell chronoatlas of regenerating mouse livers reveals early Kupffer cell proliferation

The liver is exemplar to study tissue regeneration due to its inherent ability of repair and regrowth. It replaces its lost or injured tissue by the proliferation, interaction and temporal coordination of multiple residential cell types. Until now we lacked a detailed description of the specific contributions of each cell type to the regenerative process, and therefore analyzed mouse livers 0, 3, 6, and 24 hours following two-thirds partial hepatectomy (PHx) by single cell RNA-sequencing (scRNA-seq) and mass cytometry. Our resulting genome wide temporal atlas contains the time dependent transcriptional changes in hepatocytes, endothelial cells, bone marrow-derived macrophages (BMDM) and Kupffer cells. In addition, it describes the cell specific contribution of mitogenic growth factors from biliary epithelial, endothelial and stellate cells as well as chemokines and cytokines from BMDM and granulocytes. And interestingly, Kupffer cells as opposed to hepatocytes emerged as the first cell to proliferate presenting a new dynamic in the liver following PHx. Here, we provide a robust data set at cellular resolution to uncover new elements and revisit current dogmas on the mechanisms underlying liver regeneration. To facilitate access to the data, we have launched the portal www.phxatlas.ch in which the scRNA-seq data can be visualized.

developmental biology↗

bioRxiv2018

Connexin-43 dependent ATP release mediates macrophage activation during peritonitis

Peritonitis is the consequence of bacterial spillage into a sterile environment by gastrointestinal hollow-organ perforation that may lead to fulminant sepsis. Outcome of peritonitis-induced sepsis critically depends on macrophage activation by extracellular ATP release and associated para- and autocrine signaling via purinergic receptors. Mechanisms that mediate and control ATP release, however, are poorly understood. Here we show that TLR-2 and -4 agonists trigger ATP release via Connexin-43 (CX43) hemichannels in peritoneal macrophages leading to poor survival during sepsis. In humans, CX43 expression was upregulated on macrophages isolated from the peritoneal cavity in patients with intraperitoneal infection but not in healthy controls. Using a murine caecal ligation and puncture (CLP) model, we identified increased CX43 expression in activated infiltrating peritoneal, hepatic and pulmonary macrophages. Conditional MAC-CX43 KO Lyz2cre/creCx43flox/flox mice were developed to specifically assess the CX43 impact in macrophages. Both macrophage-specific CX43 deletion (using Lyz2cre/creCx43flox/flox mice) or pharmacological CX43 blockade were associated with reduced cytokine secretion by macrophages in response to LPS and CLP. This was ultimately resulting in increased survival in Lyz2cre/creCx43flox/flox mice and after pharmacological blockade. Specific inhibition of the purinergic receptor P2RY1 abrogated CX43 elicited cytokine responses. In conclusion, inhibition of autocrine ATP signaling via CX43 on macrophages and P2RY1 improves sepsis outcome in experimental peritonitis.\n\nBrief SummaryConnexin-43-mediated ATP release from macrophages in response to TLR-4 and -2 agonists modulates autocrine activation of macrophages in a P2Y1-dependent manner, ultimately determining sepsis survival.

immunology↗