Alcohol reversibly disrupts TNF-α/TACE interactions in the cell membrane

BACKGROUND: Alcohol abuse has long been known to adversely affect innate and adaptive immune responses and pre-dispose to infections. One cellular mechanism responsible for this effect is alcohol-induced suppression of TNF-α (TNF) by mononuclear phagocytes. We have previously shown that alcohol in part inhibits TNF-α processing by TNF converting enzyme (TACE) in human monocytes. We hypothesized that the chain length of the alcohol is critical for post-transcriptional suppression of TNF secretion. METHODS: Due to the complex transcriptional and post-transcriptional regulation of TNF in macrophages, to specifically study TNF processing at the cell membrane we performed transient transfections of A549 cells with the TNF cDNA driven by the heterologous CMV promoter. TNF/TACE interactions at the cell surface were assessed using fluorescent resonance energy transfer (FRET) microscopy. RESULTS: The single carbon alcohol, methanol suppressed neither TNF secretion nor FRET efficiency between TNF and TACE. However, 2, 3, and 4 carbon alcohols were potent suppressors of TNF processing and FRET efficiency. The effect of ethanol, a 2-carbon alcohol was reversible. CONCLUSION: These data show that inhibition of TNF-α processing by acute ethanol is a direct affect of ethanol on the cell membrane and is reversible upon cessation or metabolism

PKCα and PKCδ Regulate ADAM17-Mediated Ectodomain Shedding of Heparin Binding-EGF through Separate Pathways

Epidermal growth factor receptor (EGFR) signalling is initiated by the release of EGFR-ligands from membrane-anchored precursors, a process termed ectodomain shedding. This proteolytic event, mainly executed by A Disintegrin And Metalloproteases (ADAMs), is regulated by a number of signal transduction pathways, most notably those involving protein kinase C (PKC). However, the molecular mechanisms of PKC-dependent ectodomain shedding of EGFR-ligands, including the involvement of specific PKC isoforms and possible functional redundancy, are poorly understood. To address this issue, we employed a cell-based system of PMA-induced PKC activation coupled with shedding of heparin binding (HB)-EGF. In agreement with previous studies, we demonstrated that PMA triggers a rapid ADAM17-mediated release of HB-EGF. However, PMA-treatment also results in a protease-independent loss of cell surface HB-EGF. We identified PKCα as the key participant in the activation of ADAM17 and suggest that it acts in parallel with a pathway linking PKCδ and ERK activity. While PKCα specifically regulated PMA-induced shedding, PKCδ and ERK influenced both constitutive and inducible shedding by apparently affecting the level of HB-EGF on the cell surface. Together, these findings indicate the existence of multiple modes of regulation controlling EGFR-ligand availability and subsequent EGFR signal transduction

Brentuximab vedotin. A new targeted approach for the treatment of relapsed or refractory Hodgkin's lymphoma patients

Brentuximab vedotin is a new antibody drug conjugate consisting of a monoclonal antibody which is specifically linked to a potent synthetic cytostatic drug. This construct is directed against the CD30 antigen that is highly expressed on the malignant cells of Hodgkin's lymphoma (HL) tumors. A systematic review of the current status of therapy of HL with brentuximab vedotin is presented. A systematic literature search was performed in Pubmed, MEDLINE, current guidelines and by manual searching. Relevant publications from the last 5 years were analyzed and the results are summarized in a structured review. Brentuximab vedotin has demonstrated high clinical activity in trials performed in intensively pretreated patients with HL showing an overall response rate (ORR) of 75 %. The most commonly observed side effects include moderate neutropenia and more rarely peripheral neuropathy. Brentuximab vedotin was registered by the European Medicines Agency (EMA) in October 2012 for the treatment of relapsed and refractory HL patients in Europe. With the approval of brentuximab vedotin a new standard of care for patients with relapsed or refractory HL has become available. Current clinical trials are evaluating brentuximab vedotin as a combination partner for conventional chemotherapy in first and second line treatment. Moreover, brentuximab vedotin has been used as bridging treatment before allogeneic stem cell transplantation in patients with multiple recurrences