Research progress on biodegradable polymeric platforms for targeting antibiotics to the bone

The treatment of bone infections still involves systemic or local antibiotic therapy in high doses for prolonged periods. Current research focuses on the application of different drug delivery systems to the bone, aiming at a targeted local administration that will decrease the number of drugs used and their toxicity, compared to the systemic route. The gold standard in clinical practice is currently poly(methyl methacrylate) (PMMA) cement. The main drawback of PMMA, however, is that it is non-biodegradable, requiring a second follow-up surgery to remove the implant. Biodegradable delivery systems, on the other hand, are easily resorbable within the organism, and less invasive alternative with better patient compliance. Among biodegradable materials, natural and synthetic polymers are being studied as local drug delivery systems due to their excellent biocompatibility, sustained effect, and antibiotic release with high penetrability to infected bone and soft tissue. In this review, we focus on biodegradable polymeric platforms, such as micro- and nanoparticles, scaffolds, and hydrogels, as well as multi-delivery systems for targeting antibiotics to the bone. Additionally, we discuss the reported drug release profiles that provide important information about the systems' functionality.

Poly(DL-lactic acid) scaffolds as a bone targeting platform for the co-delivery of antimicrobial agents against S. aureus-C. albicans mixed biofilms

New strategies for the treatment of polymicrobial bone infections are required. In this study, the co-delivery of two antimicrobials by poly(D,L-lactic acid) (PDLLA) scaffolds was investigated in a polymicrobial biofilm model. PDLLA scaffolds were prepared by solvent casting/particulate leaching methodology, incorporating minocycline and voriconazole as clinically relevant antimicrobial agents. The scaffolds presented a sponge-like appearance, suitable to support cell proliferation and drug release. Single- and dual-species biofilm models of Staphylococcus aureus and Candida albicans were developed and characterized. S. aureus presented a higher ability to form single-species biofilms, compared to C. albicans. Minocycline and voriconazole-loaded PDLLA scaffolds showed activity against S. aureus and C. albicans single- and dual-biofilms. Ultimately, the cytocompatibility/functional activity of PDLLA scaffolds observed in human MG-63 osteosarcoma cells unveil their potential as a next-generation co-delivery system for antimicrobial therapy in bone infections.

Targeted massively parallel sequencing for congenital generalized lipodystrophy

Objective

Our aim is to establish genetic diagnosis of congenital generalized lipodystrophy (CGL) using targeted massively parallel sequencing (MPS), also known as next-generation sequencing (NGS).

Methods

Nine unrelated individuals with a clinical diagnosis of CGL were recruited. We used a customized panel to capture genes related to genetic lipodystrophies. DNA libraries were generated, sequenced using the Illumina MiSeq, and bioinformatics analysis was performed.

Results

An accurate genetic diagnosis was stated for all nine patients. Four had pathogenic variants in AGPAT2 and three in BSCL2. Three large homozygous deletions in AGPAT2 were identified by copy-number variant analysis.

Conclusion

Although we have found allelic variants in only 2 genes related to CGL, the panel was able to identify different variants including deletions that would have been missed by Sanger sequencing. We believe that MPS is a valuable tool for the genetic diagnosis of multi-genes related diseases, including CGL.

The effects of waste sorting in environmental microbiome, THP-1 cell viability and inflammatory responses

Workers in the waste sorting industry are exposed to diverse bioaerosols. Characterization of these bioaerosols is necessary to more accurately assess the health risks of exposure. The use of high-throughput DNA sequencing for improved analysis of microbial composition of bioaerosols, in combination with their in vitro study in relevant cell cultures, represents an important opportunity to find answers on the biological effects of bioaerosols. This study aimed to characterize by high-throughput sequencing the biodiversity present in complex aerosol mixtures retained in forklift air conditioning filters of a waste-sorting industry and its effects on cytotoxicity and secretion of proinflammatory cytokines in vitro using human macrophages derived from monocytic THP-1 cells. Seventeen filters from the filtration system from forklifts operating in one waste sorting facility and one control filter (similar filter without prior use) were analyzed using high-throughput sequencing and toxicological tests in vitro. A trend of positive correlation was seen between the number of bacterial and fungal OTUs (r = 0.47, p = 0.06). Seven filters (39%) exhibited low or moderate cytotoxicity (p < 0.05). The highest cytotoxic responses had a reduction in cell viability between 17 and 22%. Filter samples evoked proinflammatory responses, especially the production of TNFα. No significant correlation was found between fungal richness and inflammatory responses in vitro. The data obtained stress the need of thorough exposure assessment in waste-sorting industry and to take immunomodulatory properties into consideration for bioaerosols hazard characterization. The broad spectrum of microbial contamination detected in this study demonstrates that adequate monitoring of bioaerosol exposure is necessary to evaluate and minimize risks. The combined techniques can support the implementation of effective environmental monitoring programs of public and occupational health importance.

Clinical application of ACMG-AMP guidelines in HNF1A and GCK variants in a cohort of MODY families

Maturity-onset diabetes of the young (MODY) is a form of monogenic diabetes with autosomal dominant inheritance. GCK -MODY and HNF1A -MODY are the prevalent subtypes. Currently, there is growing concern regarding the correct interpretation of molecular genetic findings. The American College of Medical Genetics and Genomics (ACMG) updated guidelines to interpret and classify molecular variants. This study aimed to determine the prevalence of MODY ( GCK / HNF1A ) in a large cohort of Brazilian families, to report variants related to phenotype, and to classify them according to ACMG guidelines. One hundred and nine probands were investigated, 45% with clinical suspicion of GCK -MODY and 55% with suspicion of HNF1A -MODY. Twenty-five different variants were identified in GCK gene (30 probands-61% of positivity), and 7 variants in HNF1A (10 probands-17% of positivity). Fourteen of them were novel (12- GCK /2- HNF1A ). ACMG guidelines were able to classify a large portion of variants as pathogenic (36%- GCK /86%- HNF1A ) and likely pathogenic (44%- GCK /14%- HNF1A ), with 16% (5/32) as uncertain significance. This allows us to determine the pathogenicity classification more efficiently, and also reinforces the suspected associations with the phenotype among novel variants.

Incidental mild hyperglycemia in children: two MODY 2 families identified in Brazilian subjects

Maturity-onset diabetes of the young (MODY) is characterized by an autosomal dominant mode of inheritance, early onset of hyperglycemia, and defects of insulin secretion. MODY subtypes described present genetic, metabolic, and clinical differences. MODY 2 is characterized by mild asymptomatic fasting hyperglycemia, and rarely requires pharmacological treatment. Hence, precise diagnosis of MODY is important for determining management and prognosis. We report two heterozygous GCK mutations identified during the investigation of short stature. Case 1: a prepubertal 14-year-old boy was evaluated for constitutional delay of growth and puberty. During follow-up, he showed abnormal fasting glucose (113 mg/dL), increased level of HbA1c (6.6%), and negative β-cell antibodies. His father and two siblings also had slightly elevated blood glucose levels. The mother had normal glycemia. A GCK heterozygous missense mutation, p.Arg191Trp, was identified in the proband. Eighteen family members were screened for this mutation, and 11 had the mutation in heterozygous state. Case 2: a 4-year-old boy investigated for short stature revealed no other laboratorial alterations than elevated glycemia (118 mg/dL); β-cell antibodies were negative. His father, a paternal aunt, and the paternal grandmother also had slightly elevated glycemia, whereas his mother had normal glycemia. A GCK heterozygous missense mutation, p.Glu221Lys, was identified in the index patient and in four family members. All affected patients had mild elevated glycemia. Individuals with normal glycemia did not harbor mutations. GCK mutation screening should be considered in patients with chronic mild early-onset hyperglycemia, family history of impaired glycemia, and negative β-cell antibodies.