J. Asín

Antibiotic-eluting orthopedic device to prevent early implant associated infections: Efficacy, biocompatibility and biodistribution studies in an ovine model: Infection Prevention Using Drug Eluting Orthopedic Implants

Infection of orthopedic devices is a major complication in the postsurgical period generating important health issues and economic consequences. Prevention strategies could be based on local release of antibiotics from the orthopedic device itself to avoid adhesion and growth of bacteria. The purpose of this work is to demonstrate the efficiency to prevent these infections by a cefazolin-eluting, perforated stainless steel implant in an in vivo ovine model. The device was placed in the tibia of sheep, one group receiving cefazolin-loaded implants whereas the control group received empty implants. All implants were experimentally infected by direct inoculation of Staphylococcus aureus ATCC 6538. In vitro cytotoxicological studies were also performed to check the effect of antibiotic on cell viability, integrity, and cycle. Results showed that sheep receiving cefazolin-loaded devices were able to avoid implant-associated infections, with normal tissue healing process. The antibiotic release followed a local concentric pattern as demonstrated by high-performance liquid chromatography detection in tissues. The in vitro results indicate the lack of relevant cytotoxic effects for the maximum antibiotic concentration released by the device. These results demonstrate the efficiency and safety of cefazolin-eluting implants in an ovine model to prevent early postsurgical infections of orthopedic devices.

Congenital Hepatic Fibrosis in a Purebred Spanish Horse Foal: Pathology and Genetic Studies on PKHD1 Gene Mutations:

A 1-month-old Purebred Spanish Horse (PSH) foal presented with progressive hepatic failure culminating in death. Hepatic lesions were consistent with congenital hepatic fibrosis (CHF). Genetic studies in the PKHD1 gene in the affected foal revealed that it was heterozygous for the 2 previously described single-nucleotide polymorphisms (SNPs) linked to CHF in Swiss Franches-Montagnes (SFM) horses. In addition, 2 novel mutations were detected, the foal being homozygous for one of them and heterozygous for the other. Genetic studies in a healthy PSH population (n = 35) showed a 3-fold higher genotypic frequency for PKHD1 SNP g.49,630,834G>A and a 5-fold higher genotypic frequency for PKHD1 SNP g.49,597,760A>T compared with those reported for SFM horses. SNPs in the PKHD1 gene in CHF-affected SFM horses might not fully explain the CHF observed in the PSH. Other mutations in the PKHD1 gene could play a more important role in the PSH.

Molecular Signature of Aluminum Hydroxide Adjuvant in Ovine PBMCs by Integrated mRNA and microRNA Transcriptome Sequencing

There have been few in vivo studies on the effect of aluminum hydroxide adjuvant and its influence on the immune response to vaccination. In this study, lambs received a parallel subcutaneous treatment with either commercial vaccines containing aluminum hydroxide or an equivalent dose of this compound only with the aim of identifying the activated molecular signature. Blood samples were taken from each animal at the beginning and at the end of the experiment and PBMCs isolated. Total RNA and miRNA libraries were prepared and sequenced. After alignment to the Oar3.1 reference genome and differential expression with 3 programs, gene enrichment modeling was performed. For miRNAs, miRBase and RNAcentral databases were used for detection and characterization. Three expression comparisons were made: vaccinated animals at the beginning and at the end of the treatment, adjuvanted animals at the same times, and animals of both treatments at the end of the experiment. After exposure to both treatments, a total of 2,473; 2,980 and 429 differentially expressed genes were identified in vaccinated animals, adjuvanted animals and animals at the end of both treatments, respectively. In both adjuvant and vaccine treated animals the NF-κB signaling pathway was enriched. On the other hand, it can be observed a downregulation of cytokines and cytokine receptors in the adjuvanted group compared to the vaccinated group at the final time, suggesting a milder induction of the immune response when the adjuvant is alone. As for the miRNA analysis, 95 miRNAs were detected: 64 previously annotated in Ovis aries, 11 annotated in Bos taurus and 20 newly described. Interestingly, 6 miRNAs were differentially expressed in adjuvant treated animals, and 3 and 1 in the other two comparisons. Lastly, an integrated miRNA-mRNA expression profile was developed, in which a miRNA-mediated regulation of genes related to DNA damage stimulus was observed. In brief, it seems that aluminum-containing adjuvants are not simple delivery vehicles for antigens, but also induce endogenous danger signals that can stimulate the immune system. Whether this contributes to long-lasting immune activation or to the overstimulation of the immune system remains to be elucidated.