Christophe Créminon

Cigarette smoke (CS) inhalation causes an early inflammatory response in rodent airways by stimulating capsaicin-sensitive sensory neurons that express transient receptor potential cation channel, subfamily V, member 1 (TRPV1) through an unknown mechanism that does not involve TRPV1. We hypothesized that 2 alpha,beta-unsaturated aldehydes present in CS, crotonaldehyde and acrolein, induce neurogenic inflammation by stimulating TRPA1, an excitatory ion channel coexpressed with TRPV1 on capsaicin-sensitive nociceptors. We found that CS aqueous extract (CSE), crotonaldehyde, and acrolein mobilized Ca2+ in cultured guinea pig jugular ganglia neurons and promoted contraction of isolated guinea pig bronchi. These responses were abolished by a TRPA1-selective antagonist and by the aldehyde scavenger glutathione but not by the TRPV1 antagonist capsazepine or by ROS scavengers. Treatment with CSE or aldehydes increased Ca2+ influx in TRPA1-transfected cells, but not in control HEK293 cells, and promoted neuropeptide release from isolated guinea pig airway tissue. Furthermore, the effect of CSE and aldehydes on Ca2+ influx in dorsal root ganglion neurons was abolished in TRPA1-deficient mice. These data identify alpha,beta-unsaturated aldehydes as the main causative agents in CS that via TRPA1 stimulation mediate airway neurogenic inflammation and suggest a role for TRPA1 in the pathogenesis of CS-induced diseases.

Prion diseases are transmissible neurodegenerative disorders affecting humans and animals for which no therapeutic or prophylactic regimens exist. During the last three years several studies have shown that anti-PrP monoclonal antibodies (mAbs) can antagonize prion propagation in vitro and in vivo, but the mechanisms of inhibition are not known so far. To identify the most powerful mAbs and characterize more precisely the therapeutic effect of anti-PrP antibodies, we have screened 145 different mAbs produced in our laboratory for their capacity to cure cells constitutively expressing PrPSc. Our results confirm for a very large series of antibodies that mAbs recognizing cell-surface native PrPc can efficiently clean and definitively cure infected cells. Antibodies having a cleaning effect are directed against linear epitopes located in at least four different regions of PrP, suggesting an epitope-independent inhibition mechanism. The consequence of antibody binding is the sequestration of PrPc at the cell surface, an increase of PrPc levels recovered in cell culture medium, and an internalization of antibodies. Taken together these data suggest that the cleaning process is more likely due to a global effect on the PrP trafficking and/or transconformation process. Two antibodies, Sha31 and BAR236, show an IC50 of 0.6 nM, thus appearing 10-fold more efficient than previous antibodies described in the literature. Finally, five co-treatments were also tested, and only one of them, described previously (SAF34 + SAF61), lowered PrPSc levels in the cells synergistically.

Inflammation appears to have a major role in the development of atherosclerotic lesions affecting native and transplanted coronary arteries. The subsequent risk of plaque rupture and acute ischemic events correlates with the degree of inflammation and may be modified by aspirin, an anti-inflammatory cyclooxygenase inhibitor. Cyclooxygenase-2 (Cox-2) and inducible nitric oxide synthase (iNOS) are involved in the inflammatory response via the rapid and exaggerated production of prostanoids and nitric oxide, both of which may have proatherosclerotic effects. These effects may be mediated by the formation of peroxynitrite in the case of nitric oxide and involve "cross talk" between the two enzyme systems. This study aimed to investigate native and transplant atherosclerosis for the presence and distribution of Cox-2 and iNOS. Immunocytochemical studies were performed on atherosclerotic lesions from patients with native (n=12) and transplant (n=5) coronary disease by using antibodies to Cox-2, iNOS, and nitrotyrosine (an indicator of peroxynitrite production). Control tissue was obtained from unused donor hearts and at the time of autopsy. Cox-2 and iNOS colocalized predominantly in macrophages/foam cells in both types of atherosclerosis. Cox-2 expression was also detected in medial smooth muscle cells and endothelial cells, including those of the vasa vasorum. Nitrotyrosine was found in the same distribution as that of iNOS and was colocalized with Cox-2 in macrophages. Cox-2 and iNOS are coexpressed in native and transplant atherosclerosis, possibly allowing for interaction between the enzymes and suggesting an alternative mechanism for the benefits of aspirin via inhibition of Cox-2 activity.