Clinical Features of Optic Disc Drusen in an Ophthalmic Genetics Cohort.

MATERIALS AND METHODS: Electronic medical records of patients evaluated in the Ophthalmic Genetics clinic at the National Eye Institute (NEI) between 2008 and 2018 were searched for a superficial ODD diagnosis. Color fundus and autofluorescence images were reviewed to confirm ODD, supplemented with optical coherence tomography (OCT) in uncertain cases when available. Demographic information, examination, and genetic testing were reviewed. Disc areas and disc-to-macula distance to disc diameter ratios (DM : DD) were calculated. RESULTS: Fifty six of 6207 patients had photographically confirmed ODD (0.9%). Drusen were predominantly bilateral (66%), with a female (62%) and Caucasian (73%) predilection. ODD prevalence in our cohort of patients with inherited retinal degenerations was 2.5%, and ODD were more prevalent in the rod-cone dystrophy subgroup at 2.95% (OR = 3.3 [2.1-5.3], P < 0.001) compared to the ophthalmic genetics cohort. Usher patients were more likely to have ODD (10/132, 7.6%, OR = 9.0 [4.3-17.7], P < 0.001) and had significantly smaller discs compared to the rest of our ODD cohort (disc area: P=0.001, DM : DD: P=0.03). Discussion. While an association between ODD and retinitis pigmentosa has been reported, this study surveys a large cohort of patients with inherited eye conditions and finds the prevalence of superficial ODD is lower than that in the literature. Some subpopulations, such as rod-cone dystrophy and Usher syndrome, had a higher prevalence than the cohort as a whole.

BRCA1-IRIS promotes human tumor progression through PTEN blockade and HIF-1α activation.

BRCA1 is an established breast and ovarian tumor suppressor gene that encodes multiple protein products whose individual contributions to human cancer suppression are poorly understood. BRCA1-IRIS (also known as "IRIS"), an alternatively spliced BRCA1 product and a chromatin-bound replication and transcription regulator, is overexpressed in various primary human cancers, including breast cancer, lung cancer, acute myeloid leukemia, and certain other carcinomas. Its naturally occurring overexpression can promote the metastasis of patient-derived xenograft (PDX) cells and other human cancer cells in mouse models. The IRIS-driven metastatic mechanism results from IRIS-dependent suppression of phosphatase and tensin homolog (PTEN) transcription, which in turn perturbs the PI3K/AKT/GSK-3ß pathway leading to prolyl hydroxylase-independent HIF-1α stabilization and activation in a normoxic environment. Thus, despite the tumor-suppressing genetic origin of IRIS, its properties more closely resemble those of an oncoprotein that, when spontaneously overexpressed, can, paradoxically, drive human tumor progression.

Identification of molecular mechanisms used by Finegoldia magna to penetrate and colonize human skin.

Finegoldia magna is a Gram-positive anaerobic commensal of the human skin microbiota, but also known to act as an opportunistic pathogen. Two primary virulence factors of F. magna are the subtilisin-like extracellular serine protease SufA and the adhesive protein FAF. This study examines the molecular mechanisms F. magna uses when colonizing or establishing an infection in the skin. FAF was found to be essential in the initial adherence of F. magna to human skin biopsies. In the upper layers of the epidermis FAF mediates adhesion through binding to galectin-7 - a keratinocyte cell marker. Once the bacteria moved deeper into the skin to the basement membrane layer, SufA was found to degrade collagen IV which forms the backbone structure of the basement membrane. It also degraded collagen V, whereby F. magna could reach deeper dermal tissue sites. In the dermis, FAF interacts with collagen V and fibrillin, which presumably helps the bacteria to establish infection in this area. The findings of this study paint a clear picture of how F. magna interacts with human skin and explain how it is such a successful opportunistic pathogen in chronic wounds and ulcers.

Identification of pili on the surface of Finegoldia magna--a gram-positive anaerobic cocci.

Pili have only been discovered in the major Gram-positive pathogens in the past decade and they have been found to play an important role in colonisation and virulence. Pili have been shown to have many important functions including attachment to host tissues, mediating bacterial aggregation, biofilm formation and binding to proteins in the extracellular matrix. In this study, sortase-dependent pili have been found to be expressed on the surface of Finegoldia magna ALB8. F. magna is a Gram-positive anaerobic coccus that, primarily, is a commensal of the skin and mucous membranes, but has also been isolated from various clinical infection sites and is associated with soft-tissue abscesses, wound infections and bone and prosthetic joint infections. In this study, F. magna ALB8 was found to harbour three sortases at the pilus locus, two of which bear high similarity to class C sortases in Streptococcus pneumoniae. Two putative sortase-dependent pili proteins were found in the locus, with one being identified as the major pilus subunit, Fmp1 (F. magna pilus subunit 1), due to its high similarity to other major pilus proteins in prominent Gram-positive pathogens. The presence of sortase-dependent pili was confirmed experimentally through recombinant production of Fmp1 and production of antiserum. The Fmp1 antiserum was used in Western blot to show the presence of a high molecular weight protein ladder, characteristic of the presence of pili, in trypsin released cell wall surface proteins from F. magna. The presence of sortase-dependent pili was visually confirmed by transmission electron microscopy, which showed the binding of gold labelled anti-Fmp1 to individual pilus proteins along the pilus. Furthermore, pili could also be found to bind and interact with keratinocytes in the epidermal layer of human skin, suggesting an adhesive role for pili on F. magna. Our work represents the first description of pilus structures in F. magna. This discovery further elucidates F. magna physiology and allows for additional analysis of host-bacterial interactions in future studies.

FAF and SufA: proteins of Finegoldia magna that modulate the antibacterial activity of histones.

Many bacterial pathogens have developed methods to overcome the defences of the host innate immune system. One such defence is the release of antimicrobial peptides (AMPs). Histones have been found to function as AMPs, in addition to their main biological function of packaging and organising DNA into nucleosomes. In this study, the Gram-positive anaerobic coccus Finegoldia magna was found to bind histones by Western blot and immunoprecipitation analysis. F. magna, which is normally a commensal of the skin and mucous membranes, is also known to act as an opportunistic pathogen and has been isolated from various clinical infection sites. It was found to bind to histones extracted from human skin epidermis through its surface and extracellular adhesion protein FAF. Through FAF binding, F. magna was protected from histone bactericidal activity. Furthermore, the histones were found to be degraded by SufA, a subtilisin-like extracellular serine protease of F. magna. Hence, the results of the present study will give more insight into how F. magna persists both as a commensal organism at the basement membrane of the skin and as an opportunistic pathogen during infection.

The effect of environmental conditions on expression of Bacteroides fragilis and Bacteroides thetaiotaomicron C10 protease genes.

BACKGROUND: Bacteroides fragilis and Bacteroides thetaiotaomicron are members of the normal human intestinal microbiota. However, both organisms are capable of causing opportunistic infections, during which the environmental conditions to which the bacteria are exposed change dramatically. To further explore their potential for contributing to infection, we have characterized the expression in B. thetaiotaomicron of four homologues of the gene encoding the C10 cysteine protease SpeB, a potent extracellular virulence factor produced by Streptococcus pyogenes. RESULTS: We identified a paralogous set of genes (btp genes) in the B. thetaiotaomicron genome, that were related to C10 protease genes we recently identified in B. fragilis. Similar to C10 proteases found in B. fragilis, three of the B. thetaiotaomicron homologues were transcriptionally coupled to genes encoding small proteins that are similar in structural architecture to Staphostatins, protease inhibitors associated with Staphopains in Staphylococcus aureus. The expression of genes for these C10 proteases in both B. fragilis and B. thetaiotaomicron was found to be regulated by environmental stimuli, in particular by exposure to oxygen, which may be important for their contribution to the development of opportunistic infections. CONCLUSIONS: Genes encoding C10 proteases are increasingly identified in operons which also contain genes encoding proteins homologous to protease inhibitors. The Bacteroides C10 protease gene expression levels are responsive to different environmental stimuli suggesting they may have distinct roles in the bacterial-host interaction.

Interaction of Bacteroides fragilis and Bacteroides thetaiotaomicron with the kallikrein-kinin system.

Many bacterial pathogens interfere with the contact system (kallikrein-kinin system) in human plasma. Activation of this system has two consequences: cleavage of high-molecular-mass kininogen (HK) resulting in release of the potent proinflammatory peptide bradykinin, and initiation of the intrinsic pathway of coagulation. In this study, two species of the Gram-negative anaerobic commensal organism Bacteroides, namely Bacteroides fragilis and Bacteroides thetaiotaomicron, were found to bind HK and fibrinogen, the major clotting protein, from human plasma as shown by immunoelectron microscopy and Western blot analysis. In addition, these Bacteroides species were capable of activating the contact system at its surface leading to a significant prolongation of the intrinsic coagulation time and also to the release of bradykinin. Members of the genus Bacteroides have been known to act as opportunistic pathogens outside the gut, with B. fragilis being the most common isolate from clinical infections, such as intra-abdominal abscesses and bacteraemia. The present results thus provide more insight into how Bacteroides species cause infection.

EDTA-derivatized deoxythymidine as a tool for rapid determination of protein binding polarity to DNA by intermolecular paramagnetic relaxation enhancement.

EDTA-derivatized deoxythymidine (dT-EDTA), incorporated into DNA and complexed to Fe2+ in the presence of dithiothreitol, is a widely used reagent for sequence-specific cleavage of duplex DNA. Using HPLC/electrospray mass spectrometry, we show that cleavage is specific to Fe2+, and no cleavage occurs when DNA-EDTA is complexed to other metal ions such as Ca2+, Mn2+, and Fe3+ even after many days. Because dT-EDTA can be incorporated at any desired position of a synthetic oligonucleotide, DNA-EDTA is ideally suited for the measurement of intermolecular paramagnetic relaxation enhancement effects between a paramagnetic ion chelated to DNA-EDTA and a bound protein. Measurements on the SRY/DNA-EDTA complex using two double-stranded oligonucleotides bearing dT-EDTA at opposite ends of the sequence indicate that intermolecular 1HN-T2 enhancement by chelated Mn2+ can be used to readily ascertain the polarity of protein binding to DNA and to derive quantitative long-range distance information for structure refinement. In the case of the SRY-DNA complex, excellent agreement between observed and calculated 1HN-T2 paramagnetic relaxation enhancement data can be achieved with insignificant shifts in the atomic coordinates ( approximately 0.25 A for all heavy atoms) while simultaneously satisfying all other experimental restraints. A unique feature of DNA-EDTA is that the relaxation enhancement effect can be tuned by judicious choice of the paramagnetic metal ion, thereby permitting a wide range of long-range intermolecular electron-proton distances, ranging from approximately 9 to 35 A, to be probed.