007P Queen Elizabeth II Conference Centre London
BPS Winter Meeting 2011

 

 

Role of the Ion Channel TRPM2 in Inflammatory Mouse Models of Chronic Obstructive Pulmonary Diseases

Alexandre Trifilieff2, Benjamin Cochin de Billy2, Mark Freeman1, Rachel Glover1, Natalia Kupfer1, Daniel Wyss2, Liz Hardaker1. 1Novartis Institute for BioMedical Research, Respiratory Diseases Area, Horsham, UK, 2Novartis Institute for BioMedical Research, Respiratory Diseases Area, Basel, Switzerland

 

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. Male and female mice were used in these studies. Animals were exposed to ozone (3ppm for 4 h) or lipopolysaccharide (LPS, 0.3 mg/kg, intranasaly). In another model, mice were exposed to tobacco smoke (750µg/l total wet particulate matter) for 30 min twice a day on three consecutive days with at least a 5 h gap between each exposure. For the exacerbation model, the smoke exposure on the morning of day 3 animals was replaced with intranasal administration of lipopolysaccharide (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, by intraperitoneal injection of pentobarbitone (250 mg/kg). Data are expressed as means±SEM (n = 7-11) and statistical significance (P < 0.05) was determined using analysis of variance with Kruskal-Wallis and Dunns multiple comparison test. Cell numbers (105 cells) and soluble mediators (ng/ml) were measured in the bronchoalveolar lavage.

As shown in the table below, in all models studied, no difference in the bronchoalveolar lavage inflammation could be evidenced when comparing wild type (WT) and TRPM2-deficient (KO) mice. In addition, no difference could be seen in the lung inflammation as measured by measurement of various cytokines/chemokines.

Ozone 3 h Ozone 24h LPS 3 h LPS 24h Smoke Exacerbation
Neutrophil
WT
KO
0.64±0.08
1.07±0.14
1.92±0.30
1.90±0.37
0.41±0.12
0.50±0.13
1.23±0.26
1.02±0.19
2.66±0.23
2.14±0.24
0.35±0.08
0.48±0.11
CXCL1
WT
KO
0.83±0.05
0.94±0.05
0.19±0.01
0.16±0.02
8.6±1.1
13.3±1.6
1.9±0.4
2.2±0. 6
1.1±0.2
1.0±0.1
6.9±1.7
4.3±0.8
CXCL2
WT
KO
0.35±0.03
0.35±0.04
0.18±0.01
0.14±0.01
4.2±0.5
5.7±0.8
1.1±0.1
1.1±0.1
Not done
Not done
Not done
Not done
IL-6
WT
KO
0.51±0.08
0.66±0.07
0.06±0.01
0.05±0.01
1.9±0.2
2.8±0.4
1.0±0.2
0.9±0.2
0.13±0.10
0.13±0.12
1.2±.0.5
1.1±0.3

We have shown that in a mechanistic model of oxidative stress-induced lung injury (ozone exposure) and in several models thought to reproduce aspects of the inflammation observed in COPD, TRPM2-deficiency did not affect the development of airway inflammation. These data suggest that TRPM2 blockers may not have beneficial effect in patients with COPD.