The ion channel transient receptor potential melastatin-2 does not play a role in inflammatory mouse models of chronic obstructive pulmonary diseases

<p>Abstract</p> <p>Background</p> <p>There is strong evidence that oxidative stress is associated with the pathogenesis of chronic obstructive pulmonary disease (COPD). The transient receptor potential melastatin-2 (TRPM2) is an oxidative stress sensing channel that is expressed in a number of inflammatory cells and therefore it has been suggested that inhibition of TRPM2 could lead to a beneficial effect in COPD patients. In this study, we have investigated the role of TRPM2 in a variety of mouse models of oxidative stress and COPD using TRPM2-deficent mice.</p> <p>Methods</p> <p>Mice were exposed to ozone (3 ppm for 4 h) or lipopolysaccharide (LPS, 0.3 mg/kg, intranasaly). In another model, mice were exposed to tobacco smoke (750 μg/l total wet particulate matter) for 30 min twice a day on three consecutive days. For the exacerbation model, the smoke exposure on the morning of day 3 animals was replaced with intranasal administration of LPS (0.3 mg/kg). Animals were killed 3 and 24 h after the challenge (ozone and LPS model) or 18 h after the last tobacco smoke exposure. In vitro neutrophil chemotaxis and monocyte activation were also studied using cells isolated from wild type and TRPM2-deficient animals. Statistical significance for the in vivo data (<it>P </it>< 0.05) was determined using analysis of variance with Kruskal-Wallis and Dunns multiple comparison test.</p> <p>Results</p> <p>In all models studied, no difference in the bronchoalveolar lavage inflammation could be evidenced when comparing wild type and TRPM2-deficient mice. In addition, no difference could be seen in the lung inflammation as assessed by the measurement of various cytokines/chemokines. Similarly in various in vitro cellular activation assays using isolated neutrophils and monocytes no significant differences could be observed when comparing wild type and TRPM2-deficient mice.</p> <p>Discussion</p> <p>We have shown, in all the models tested, no difference in the development of airway inflammation or cell activation between TRPM2-deficient mice and their wild type counterparts. These results would suggest that inhibiting TRPM2 activity in COPD would have no anti-inflammatory effect.</p

An afucosylated anti-CD32b monoclonal antibody induced platelet-mediated adverse events in human Fcg receptor transgenic mouse model and its potential human translatability

A monoclonal, afucosylated, anti-CD32b (FCGR2B) antibody, NVS32b, was developed internally as a therapeutic candidate for treatment of B-cell malignancies. To assess its safety and tolerability, a humanized transgenic (Tg) mouse model that reportedly expresses all human Fc gamma receptors (FCGRs) while lacking all mouse FCGRs was used. Prior to its use, the model was extensively characterized and found to express all human FCGRs in a pattern similar to humans, with some deviations, such as low CD32 expression on T cells, substantial individual variation in the transgene copy number, integration of additional human genes, and overall higher expression of all FCGRs on myeloid cells compared to human. Unexpectedly, NVS32b induced severe thrombosis in huFCGR mice. The mechanism and relevance for human was further investigated. Species differences, in the NVS32b-driven in vitro platelet binding, activation and aggregation were observed (CD32a-binding by Fc and CDR of NVS32b causing platelet activation in huFCGR mice opposing to CD32a-binding by Fc and off-target-binding by CDR of NVS32b only after platelet activation in human). Therefore huFCGR mice may not be fully predictive of the risk of NVS32b-induced thromboembolic events in the clinic. Nevertheless the program was terminated as a result of this potential safety liability. This model could be considered beneficial in the pre-clinical research of immunotherapies targeting or involving FCGRs. While potential biological implications resulting from the differences in theFCGR expression pattern in humans cannot be predicted, these deviations should be considered and further evaluated when using this huFCGR mouse model