Overturning the paradigm that IL6 signaling drives liver regrowth while shining light on a new therapeutic target for regenerative medicine

It is accepted that IL6 signaling in hepatocytes, mediated via glycoprotein 130 (gp130), is beneficial and that HyperIL6 promotes liver regeneration by activating STAT3. Recently, autocrine IL11 activity, which also signals via gp130 and ERK, was found to be hepatotoxic. Here we examined whether the beneficial effects of HyperIL6 could reflect unappreciated competitive inhibition of IL11 signaling. In hepatocytes, HyperIL6 inhibited N-acetyl-p-aminophenol (APAP)-induced cell death that mimicked inhibition of IL11 signaling and was unrelated to STAT3 phosphorylation. In mice, expression of HyperIL6 reduced liver damage due to IL11 dosing or APAP and promoted hepatic regeneration in a STAT3-independent manner. Following APAP, mice deleted for Il11 were protected from liver failure and exhibited spontaneous regeneration. Despite robustly activating STAT3, HyperIL6 had no beneficial effect in Il11 null mice. These data overturn the premise that IL6 promotes liver regeneration, show STAT3 activation to be redundant and suggest IL11 as a focus for regenerative medicine.