Chemerin Impairs In Vitro Testosterone Production, Sperm Motility, and Fertility in Chicken: Possible Involvement of Its Receptor CMKLR1

International audienceThe chemokine chemerin is a novel adipokine involved in the regulation of energy metabolism but also female reproductive functions in mammals. Its effects on male fertility are less studied. Here, we investigated the involvement of chemerin in chicken male reproduction. Indeed, the improvement of the sperm of roosters is a challenge for the breeders since the sperm quantity and quality have largely decreased for several years. By using specific chicken antibodies, here we show that chemerin and its main receptor CMKLR1 (chemokine-like receptor 1) are expressed within the chicken testis with the lowest expression in adults as compared to the embryo or postnatal stages. Chemerin and CMKLR1 are present in all testicular cells, including Leydig, Sertoli, and germinal cells. Using in vitro testis explants, we observed that recombinant chicken chemerin through CMKLR1 inhibits hCG (human chorionic gonadotropin) stimulated testosterone production and this was associated to lower 3βHSD (3beta-hydroxysteroid dehydrogenase) and StAR (steroidogenic acute regulatory protein) expression and MAPK ERK2 (Mitogen-Activated Protein Kinase Extracellular signal-regulated kinase 2) phosphorylation. Furthermore, we demonstrate that chemerin in seminal plasma is lower than in blood plasma, but it is negatively correlated with the percentage of motility and the spermatozoa concentration in vivo in roosters. In vitro, we show that recombinant chicken chemerin reduces sperm mass and individual motility in roosters, and this effect is abolished when sperm is pre-incubated with an anti-CMKLR1 antibody. Moreover, we demonstrate that fresh chicken sperm treated with chemerin and used for artificial insemination (AI) in hen presented a lower efficiency in terms of eggs fertility for the four first days after AI. Taken together, seminal chemerin levels are negatively associated with the rooster fertility, and chemerin produced locally by the testis or male tract could negatively affect in vivo sperm quality and testosterone production through CMKLR1

Implementation of Model-Based Dose Adjustment of Tobramycin in Adult Patients with Cystic Fibrosis

Therapeutic drug monitoring (TDM) of tobramycin is widely performed in patients with cystic fibrosis (CF), but little is known about the value of model-informed precision dosing (MIPD) in this setting. We aim at reporting our experience with tobramycin MIPD in adult patients with CF. We analyzed data from adult patients with CF who received IV tobramycin and had model-guided TDM during the first year of implementation of MIPD. The predictive performance of a pharmacokinetic (PK) model was assessed. Observed maximal (Cmax) and minimal (Cmin) concentrations after initial dosing were compared with target values. We compared the initial doses and adjusted doses after model-based TDM, as well as renal function at the beginning and end of therapy. A total of 78 tobramycin courses were administered in 61 patients. After initial dosing set by physicians (mean, 9.2 ± 1.4 mg/kg), 68.8% of patients did not achieve the target Cmax ≥ 30 mg/L. The PK model fit the data very well, with a median absolute percentage error of 4.9%. MIPD was associated with a significant increase in tobramycin doses (p < 0.001) without significant change in renal function. Model-based dose suggestions were wellaccepted by the physicians and the expected target attainment for Cmax was 83%. To conclude, the implementation of MIPD was effective in changing prescribing practice and was not associated with nephrotoxic events in adult patients with CF

Pattern and causes of the establishment of the invasive bacterial potato pathogen Dickeya solani and of the maintenance of the resident pathogen D. dianthicola

International audienceInvasive pathogens can be a threat when they affect human health, food production or ecosystem services, by displacing resident species, and we need to understand the cause of their establishment. We studied the patterns and causes of the establishment of the pathogen Dickeya solani that recently invaded potato agrosystems in Europe by assessing its invasion dynamics and its competitive ability against the closely related resident D. dianthicola species. Epidemiological records over one decade in France revealed the establishment of D. solani and the maintenance of the resident D. dianthicola in potato fields exhibiting blackleg symptoms. Using experimentations, we showed that D. dianthicola caused a higher symptom incidence on aerial parts of potato plants than D. solani, while D. solani was more aggressive on tubers (i.e. with more severe symptoms). In co-infection assays, D. dianthicola outcompeted D. solani in aerial parts, while the two species co-existed in tubers. A comparison of 76 D. solani genomes (56 of which have been sequenced here) revealed balanced frequencies of two previously uncharacterized alleles, VfmBPro and VfmBSer, at the vfmB virulence gene. Experimental inoculations showed that the VfmBSer population was more aggressive on tubers, while the VfmBPro population outcompeted the VfmBSer population in stem lesions, suggesting an important role of the vfmB virulence gene in the ecology of the pathogens. This study thus brings novel insights allowing a better understanding of the pattern and causes of the D.solani invasion into potato production agrosystems, and the reasons why the endemic D. dianthicola nevertheless persisted