Depletion of myeloid cells exacerbates hepatitis and induces an aberrant increase in histone H3 in mouse serum

Abstract

Tissue-resident macrophages and bone marrow (BM)-derived monocytes play a crucial role in the maintenance of tissue homeostasis; however, their contribution to recovery from acute tissue injury is not fully understood. To address this issue, we generated an acute murine liver injury model using hepatocyte-specific Cflar-deficient (Cflar Hep-low ) mice. Cellular FLICE-inhibitory protein expression was down-regulated in Cflar-deficient hepatocytes, which thereby increased susceptibility of hepatocytes to death receptor-induced apoptosis. Cflar Hep-low mice developed acute hepatitis and recovered with clearance of apoptotic hepatocytes at 24 hours after injection of low doses of tumor necrosis factor a (TNFa), which could not induce hepatitis in wild-type (WT) mice. Depletion of Kupffer cells (KCs) by clodronate liposomes did not impair clearance of dying hepatocytes or exacerbate hepatitis in Cflar Hep-low mice. To elucidate the roles of BM-derived monocytes and neutrophils in clearance of apoptotic hepatocytes, we examined the effect of depletion of these cells on TNFa-induced hepatitis in Cflar Hep-low mice. We reconstituted Cflar Hep-low mice with BM cells from transgenic mice in which human diphtheria toxin receptor (DTR) was expressed under control of the lysozyme M (LysM) promoter. TNFa-induced infiltration of myeloid cells, including monocytes and neutrophils, was completely ablated in LysM-DTR BM-reconstituted Cflar Hep-low mice pretreated with diphtheria toxin, whereas KCs remained present in the livers. Under these experimental conditions, LysM-DTR BM-reconstituted Cflar Hep-low mice rapidly developed severe hepatitis and succumbed within several hours of TNFa injection. We found that serum interleukin-6 (IL-6), TNFa, and histone H3 were aberrantly increased in LysM-DTR BM-reconstituted, but not in WT BM-reconstituted, Cflar Hep-low mice following TNFa injection. Conclusion: These findings indicate an unexpected role of myeloid cells in decreasing serum IL-6, TNFa, and histone H3 levels via the suppression of TNFa-induced hepatocyte apoptosis. (HEPATOLOGY 2017;65:237-252).

A FRET biosensor for necroptosis uncovers two different modes of the release of DAMPs

“…MEFs and aMoC1 cells were plated onto 96-well plates and cultured for 12 h in 10% DMEM. Cells were stimulated with mTNF (10 ng ml −1 ) in the absence or presence of BV6 (1 μM), GSK’872 (5 μM), zVAD (20 μM), or Nec-1 (20 μM) for 8 h. The values of LDH release from cells were determined by Cytotoxicity Detection Kit (Roche) as described previously 13 .…”

“…Intriguingly, IL-33 is cleaved by caspase 3 in apoptotic cells, resulting in the inactivation of its biological activity 12 . Moreover, we recently reported that large amounts of histone H3 are released from apoptotic hepatocytes and potentially involved in the development of endothelial cell injury in the livers and lungs 13 . Together, these results suggest that DAMPs are critically involved in inflammation, immune responses, and tissue injury.…”

A murine model of acute lung injury identifies growth factors to promote tissue repair and their biomarkers

“…Metabolome analysis was performed as previously described (Piao et al, ). Briefly, fifty microliters of the sera from mice of the indicated genotype before or after DT treatment was used for the analysis of ionic metabolites.…”

Suberoylanilide hydroxamic acid alleviates orthotopic liver transplantation‑induced hepatic ischemia‑reperfusion injury by regulating the AKT/GSK3β/NF‑κB and AKT/mTOR pathways in rat Kupffer cells

“…The mRNA and protein levels of ATG5 were measured by RT-qPCR and western blotting, respectively. To deplete Kcs in the donor livers, clodronate liposomes (cLs) were used as before (37). Then KCs (2x10 7 cells) that were isolated from the liver tissue of AAV-ATG5-shRNA-or scramble-treated rats, were injected into recipients via the portal vein during OLT (38).…”

“…For the IR+SA group, the donors and recipients were both intraperitoneally injected with a dose of 50 mg/kg SAHA (MedchemExpress) 12 h prior to operation, and the recipients continued to receive 50 mg/kg SAHA q12 h right from reperfusion via intra-peritoneal injection (39). For the IR+SA+CL group, cL (Encapsula NanoSciences) were injected into the donors at a dose of 4 µl/g body weight via the tail vein 48 h prior to surgery according to the manufacturer's protocol (37). Depletion of KCs were verified by using flow cytometry and immunohistochemistry, respectively.…”