CD40 Ligation Protects Bronchial Epithelium against Oxidant-Induced Caspase-Independent Cell Death

Abstract

CD40 and its ligand regulate pleiotropic biological responses, including cell proliferation, differentiation, and apoptosis. In many inflammatory lung diseases, tissue damage by environmental or endogenous oxidants plays a major role in disease pathogenesis. As the epithelial barrier is a major target for these oxidants, we postulated that CD40, the expression of which is increased in asthma, plays a role in the regulation of apoptosis of bronchial epithelial cells exposed to oxidants. Using 16HBE 14o؊ cells exposed to oxidant stress, we found that ligation of CD40 (induced by G28-5 monoclonal antibodies) enhanced cell survival and increased the number of cells in G2/M (interphase between DNA synthesis and mitosis) of the cell cycle. This was associated with NF-B and activator protein-1 activation and increased expression of the inhibitor of apoptosis, c-IAP1. However, oxidant stress-induced apoptosis was found to be caspase-and calpain-independent implicating CD40 ligation as a regulator of caspase-independent cell death. This was confirmed by the demonstration that CD40 ligation prevented mitochondrial release and nuclear translocation of apoptosis inducing factor. In conclusion, we demonstrate a novel role for CD40 as a regulator of epithelial cell survival against oxidant stress. Furthermore, we have identified, for the first time, an endogenous inhibitory pathway of caspase-independent cell death.

Cysteinyl Leukotriene-1 Receptor Activation in a Human Bronchial Epithelial Cell Line Leads to Signal Transducer and Activator of Transcription 1-Mediated Eosinophil Adhesion

“…The 16HBE cell line was cultured as an adherent monolayer in Eagle's minimum essential medium supplemented with 10% heatinactivated (56°C, 30 min) fetal calf serum ϩ 100 U/ml penicillin and 100 mg/ml streptomycin. 16HBE cells have previously been used to study the functional properties of bronchial epithelial cells in inflammation (Merendino et al, 2006). Because 16HBE cells have been showing a weak and variable expression of cysLT 1 R, we enhanced and normalized its expression by transfection and transinfection with a pBH-CysLT 1 R construct.…”

The dissociation of the Hsp60/pro-Caspase-3 complex by bis(pyridyl)oxadiazole copper complex ( CubipyOXA ) leads to cell death in NCI-H292 cancer cells

“…Treated and untreated cells were lysed by submersion into ice-cold lysis solution containing radioimmunoprecipitation assay (RIPA) buffer, as previously described [23]. Cell lysates were then incubated for 30 min on ice and then centrifuged at 16,000 × g for 30 min at 4°C.…”

Epithelium dysfunction in asthma

“…26,[30][31][32] For many years, ''epithelial desquamation'' has been described as a pathological feature in asthma death, 33 but until recently, its significance has not been fully appreciated. 34,35 Bronchial biopsy studies from patients with asthma of increasing severity demonstrate not only physical damage to the columnar cell layer but also evidence for injury through the expression of cell stressors such as heat shock protein 70, 36 evidence for activation of the caspase enzyme cascade involved in apoptosis both in asthma 26,[37][38][39] and in a murine model of airway inflammation, 40 and enhanced surface expression of epidermal growth factor receptors (EGFRs), [41][42][43] as well as other receptors involved in innate immunity, including CD40 and TLRs. 44,45 These epithelial markers of stress and injury increase in proportion to disease severity and chronicity.…”