Isolation and characterization of novel glycoproteins from fish epidermal mucus: correlation between their pore-forming properties and their antibacterial activities

AbstractIn fish, a layer of mucus covers the external body surface contributing therefore, among other important biological functions, to the defense system of fish. The prevention of colonization by aquatic parasites, bacteria and fungi is mediated both by immune system compounds (IgM, lysozyme, etc.) and by antibacterial peptides and polypeptides. We have recently shown that only the hydrophobic components of crude epidermal mucus of fresh water and sea water fish exhibit strong pore-forming properties, which were well correlated with antibacterial activity [N. Ebran, S. Julien, N. Orange, P. Saglio, C. Lemaitre, G. Molle, Comp. Biochem. Physiol. 122 (1999)]. Here, we have isolated novel glycosylated proteins from the hydrophobic supernatant of tench (Tinca tinca), eel (Anguilla anguilla) and rainbow trout (Oncorhynchus mykiss) mucus. The study of their secondary structure was performed by circular dichroism and revealed structures in random coil and α-helix in the same proportions. When reconstituted in planar lipid bilayer, they induced the formation of ion channels. This pore-forming activity was well correlated with a strong antibacterial activity (minimal inhibitory concentration<1 μM for the three proteins) against both Gram-negative and Gram-positive bacteria. Our results suggest that fish secrete antibacterial glycoproteins able to kill bacteria by forming large pores (several hundreds to thousands of pS) in the target membrane

Genetic variability of environmental sensitivity revealed by phenotypic variation in body weight and (its) correlations to physiological and behavioral traits

Adaptive phenotypic plasticity is a key component of the ability of organisms to cope with changing environmental conditions. Fish have been shown to exhibit a substantial level of phenotypic plasticity in response to abiotic and biotic factors. In the present study, we investigate the link between environmental sensitivity assessed globally (revealed by phenotypic variation in body weight) and more targeted physiological and behavioral indicators that are generally used to assess the sensitivity of a fish to environmental stressors. We took advantage of original biological material, the rainbow trout isogenic lines, which allowed the disentangling of the genetic and environmental parts of the phenotypic variance. Ten lines were characterized for the changes of body weight variability (weight measurements taken every month during 18 months), the plasma cortisol response to confinement stress (3 challenges) and a set of selected behavioral indicators. This study unambiguously demonstrated the existence of genetic determinism of environmental sensitivity, with some lines being particularly sensitive to environmental fluctuations and others rather insensitive. Correlations between coefficient of variation (CV) for body weight and behavioral and physiological traits were observed. This confirmed that CV for body weight could be used as an indicator of environmental sensitivity. As the relationship between indicators (CV weight, risk-taking, exploration and cortisol) was shown to be likely depending on the nature and intensity of the stressor, the joint use of several indicators should help to investigate the biological complexity of environmental sensitivity

Pravastatin Reverses Established Radiation-Induced Cutaneous and Subcutaneous Fibrosis in Patients With Head and Neck Cancer: Results of the Biology-Driven Phase 2 Clinical Trial Pravacur

International audiencePURPOSE:The "PRAVACUR" phase 2 trial (NCT01268202) assessed the efficacy of pravastatin as an antifibrotic agent in patients with established cutaneous and subcutaneous radiation-induced fibrosis (RIF) after head and neck squamous cell carcinoma (HNSCC) radiation therapy and/or radiochemotherapy.METHODS AND MATERIALS:The main inclusion criteria were: NSCC in remission, grade ≥2 cutaneous and subcutaneous neck RIF (National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0), and no current treatment with statins or fibrates. Patients received pravastatin 40 mg/d for 12 months. The primary endpoint was reduction of RIF thickness by more than 30% at 12 months, as measured by cutaneous high-frequency ultrasonography. Secondary endpoints included RIF severity reduction, pravastatin tolerance, and quality of life.RESULTS:Sixty patients with grade 2 (n = 37), grade 3 (n = 22), or grade 4 (n = 1) RIF were enrolled from February 2011 to April 2016. The mean interval between RIF diagnosis and pravastatin initiation was 17.1 months. Pravastatin was stopped before 11 months of treatment in 18 patients (because of grade ≥2 adverse events related to pravastatin in 8 patients [13%]). In the 40 patients in whom pravastatin efficacy was assessed by high-frequency ultrasonography at baseline and at 12 months of treatment, a reduction of RIF thickness ≥30% was observed in 15 of 42 patients (35.7%; 95% confidence interval, 21.6%-52.0%). At the 12-month clinical evaluation, RIF severity was decreased in 50% of patients (n = 21; 95% confidence interval, 34.2%-65.8%), and the patients' self-perception, mood state, and social functioning were significantly improved. Pravastatin was well tolerated, with a very low occurrence of grade 3 toxicities (myalgia, n = 1) and grade 2 toxicities (myalgia/arthralgia or esophagitis, n = 3).CONCLUSIONS:This phase 2 prospective study supports the notion of radioinduced fibrosis reversibility. It showed that pravastatin (40 mg/d for 12 months) is an efficient antifibrotic agent in patients with grade ≥2 cutaneous and subcutaneous fibrosis after HNSCC radiation therapy