Genetic, structural, and functional analysis of pathogenic variations causing methylmalonyl-CoA epimerase deficiency

Human methylmalonyl-CoA epimerase (MCEE) catalyzes the interconversion of d-methylmalonyl-CoA and l-methylmalonyl-CoA in propionate catabolism. Autosomal recessive pathogenic variations in MCEE reportedly cause methylmalonic aciduria (MMAuria) in eleven patients. We investigated a cohort of 150 individuals suffering from MMAuria of unknown origin, identifying ten new patients with pathogenic variations in MCEE. Nine patients were homozygous for the known nonsense variation p.Arg47* (c.139C > T), and one for the novel missense variation p.Ile53Arg (c.158T > G). To understand better the molecular basis of MCEE deficiency, we mapped p.Ile53Arg, and two previously described pathogenic variations p.Lys60Gln and p.Arg143Cys, onto our 1.8 Å structure of wild-type (wt) human MCEE. This revealed potential dimeric assembly disruption by p.Ile53Arg, but no clear defects from p.Lys60Gln or p.Arg143Cys. We solved the structure of MCEE-Arg143Cys to 1.9 Å and found significant disruption of two important loop structures, potentially impacting surface features as well as the active-site pocket. Functional analysis of MCEE-Ile53Arg expressed in a bacterial recombinant system as well as patient-derived fibroblasts revealed nearly undetectable soluble protein levels, defective globular protein behavior, and using a newly developed assay, lack of enzymatic activity - consistent with misfolded protein. By contrast, soluble protein levels, unfolding characteristics and activity of MCEE-Lys60Gln were comparable to wt, leaving unclear how this variation may cause disease. MCEE-Arg143Cys was detectable at comparable levels to wt MCEE, but had slightly altered unfolding kinetics and greatly reduced activity. These studies reveal ten new patients with MCEE deficiency and rationalize misfolding and loss of activity as molecular defects in MCEE-type MMAuria

Antibacterial burst-release from minimal Ag-containing plasma polymer coatings

Biomaterials releasing silver (Ag) are of interest because of their ability to inhibit pathogenic bacteria including antibiotic-resistant strains. In order to investigate the potential of nanometre-thick Ag polymer (Ag/amino-hydrocarbon) nanocomposite plasma coatings, we studied a comprehensive range of factors such as the plasma deposition process and Ag cation release as well as the antibacterial and cytocompatible properties. The nanocomposite coatings released most bound Ag within the first day of immersion in water yielding an antibacterial burst. The release kinetics correlated with the inhibitory effects on the pathogens Pseudomonas aeruginosa or Staphylococcus aureus and on animal cells that were in contact with these coatings. We identified a unique range of Ag content that provided an effective antibacterial peak release, followed by cytocompatible conditions soon thereafter. The control of the in situ growth conditions for Ag nanoparticles in the polymer matrix offers the possibility to produce customized coatings that initially release sufficient quantities of Ag ions to produce a strong adjacent antibacterial effect, and at the same time exhibit a rapidly decaying Ag content to provide surface cytocompatibility within hours/days. This approach seems to be favourable with respect to implant surfaces and possible Ag-resistance/tolerance built-up

The Wnt-Driven Mll1 Epigenome Regulates Salivary Gland and Head and Neck Cancer

Summary: We identified a regulatory system that acts downstream of Wnt/β-catenin signaling in salivary gland and head and neck carcinomas. We show in a mouse tumor model of K14-Cre-induced Wnt/β-catenin gain-of-function and Bmpr1a loss-of-function mutations that tumor-propagating cells exhibit increased Mll1 activity and genome-wide increased H3K4 tri-methylation at promoters. Null mutations of Mll1 in tumor mice and in xenotransplanted human head and neck tumors resulted in loss of self-renewal of tumor-propagating cells and in block of tumor formation but did not alter normal tissue homeostasis. CRISPR/Cas9 mutagenesis and pharmacological interference of Mll1 at sequences that inhibit essential protein-protein interactions or the SET enzyme active site also blocked the self-renewal of mouse and human tumor-propagating cells. Our work provides strong genetic evidence for a crucial role of Mll1 in solid tumors. Moreover, inhibitors targeting specific Mll1 interactions might offer additional directions for therapies to treat these aggressive tumors. : Mutations of Mll1 genes were described in leukemia, but little is known about the roles of Mll1 in solid tumors. Zhu et al. provide genetic evidence for a crucial role of Mll1 in Wnt/β-catenin-driven salivary gland and head and neck cancers. Keywords: tumor-propagating cells, epigenetics, solid tumors, ChIP-seq, H3K4me3 at promoters, SET domain, Axin

Stage III N2 non-small cell lung cancer treatment: decision-making among surgeons and radiation oncologists.

Background Stage III N2 non-small cell lung cancer (NSCLC) is a very heterogeneous disease associated with a poor prognosis. A number of therapeutic options are available for patients with Stage III N2 NSCLC, including surgery [with neoadjuvant or adjuvant chemotherapy (CTx)/neoadjuvant chemoradiotherapy (CRT)] or CRT potentially followed by adjuvant immunotherapy. We have no clear evidence demonstrating a significant survival benefit for either of these approaches, the selection between treatments is not always straightforward and can come down to physician and patient preference. The very heterogeneous definition of resectability of N2 disease makes the decision-making process even more complex. Methods We evaluated the treatment strategies for preoperatively diagnosed stage III cN2 NSCLC among Swiss thoracic surgeons and radiation oncologists. Treatment strategies were converted into decision trees and analysed for consensus and discrepancies. We analysed factors relevant to decision-making within these recommendations. Results For resectable "non-bulky" mediastinal lymph node involvement, there was a trend towards surgery. Numerous participants recommend a surgical approach outside existing guidelines as long as the disease was resectable, even in multilevel N2. With increasing extent of mediastinal nodal disease, multimodal treatment based on radiotherapy was more common. Conclusions Both, surgery- or radiotherapy-based treatment regimens are feasible options in the management of Stage III N2 NSCLC. The different opinions reflected in the results of this manuscript reinforce the importance of a multidisciplinary setting and the importance of shared decision-making with the patient

Surveillance of invasive pneumococcal disease in 30 EU countries: Towards a European system?

In this era of new pneumococcal conjugate vaccines (PCV), we described and compared surveillance of invasive pneumococcal disease (IPD) and PCV policies in 30 European countries to provide guidance for Europe-wide surveillance. We confirmed the heterogeneity of surveillance systems and case definitions across countries but identified elements common to all countries, such as the availability of serotyping and the surveillance of pneumococcal meningitis. PCV impact was monitored in 11/15 countries using it. We propose steps for the monitoring of incidence rates and serotype distribution at EU level, to assess the need to introduce PCV and monitor its impact once introduced.Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Serotype-specific changes in invasive pneumococcal disease after pneumococcal conjugate vaccine introduction: a pooled analysis of multiple surveillance sites

BACKGROUND: Vaccine-serotype (VT) invasive pneumococcal disease (IPD) rates declined substantially following introduction of 7-valent pneumococcal conjugate vaccine (PCV7) into national immunization programs. Increases in non-vaccine-serotype (NVT) IPD rates occurred in some sites, presumably representing serotype replacement. We used a standardized approach to describe serotype-specific IPD changes among multiple sites after PCV7 introduction. METHODS AND FINDINGS: Of 32 IPD surveillance datasets received, we identified 21 eligible databases with rate data ≥ 2 years before and ≥ 1 year after PCV7 introduction. Expected annual rates of IPD absent PCV7 introduction were estimated by extrapolation using either Poisson regression modeling of pre-PCV7 rates or averaging pre-PCV7 rates. To estimate whether changes in rates had occurred following PCV7 introduction, we calculated site specific rate ratios by dividing observed by expected IPD rates for each post-PCV7 year. We calculated summary rate ratios (RRs) using random effects meta-analysis. For children <5 years old, overall IPD decreased by year 1 post-PCV7 (RR 0.55, 95% CI 0.46-0.65) and remained relatively stable through year 7 (RR 0.49, 95% CI 0.35-0.68). Point estimates for VT IPD decreased annually through year 7 (RR 0.03, 95% CI 0.01-0.10), while NVT IPD increased (year 7 RR 2.81, 95% CI 2.12-3.71). Among adults, decreases in overall IPD also occurred but were smaller and more variable by site than among children. At year 7 after introduction, significant reductions were observed (18-49 year-olds [RR 0.52, 95% CI 0.29-0.91], 50-64 year-olds [RR 0.84, 95% CI 0.77-0.93], and ≥ 65 year-olds [RR 0.74, 95% CI 0.58-0.95]). CONCLUSIONS: Consistent and significant decreases in both overall and VT IPD in children occurred quickly and were sustained for 7 years after PCV7 introduction, supporting use of PCVs. Increases in NVT IPD occurred in most sites, with variable magnitude. These findings may not represent the experience in low-income countries or the effects after introduction of higher valency PCVs. High-quality, population-based surveillance of serotype-specific IPD rates is needed to monitor vaccine impact as more countries, including low-income countries, introduce PCVs and as higher valency PCVs are used. Please see later in the article for the Editors' Summary