PRDM16 Deletion Is Associated With Sex-dependent Cardiomyopathy and Cardiac Mortality: A Translational, Multi-Institutional Cohort Study.

BACKGROUND: 1p36 deletion syndrome can predispose to pediatric-onset cardiomyopathy. Deletion breakpoints are variable and may delete the transcription factor PRDM16. Early studies suggest that deletion of PRDM16 may underlie cardiomyopathy in patients with 1p36 deletion; however, the prognostic impact of PRDM16 loss is unknown. METHODS: This retrospective cohort included subjects with 1p36 deletion syndrome from 4 hospitals. Prevalence of cardiomyopathy and freedom from death, cardiac transplantation, or ventricular assist device were analyzed. A systematic review cohort was derived for further analysis. A cardiac-specific Prdm16 knockout mouse (Prdm16 conditional knockout) was generated. Echocardiography was performed at 4 and 6 to 7 months. Histology staining and qPCR were performed at 7 months to assess fibrosis. RESULTS: The retrospective cohort included 71 patients. Among individuals with PRDM16 deleted, 34.5% developed cardiomyopathy versus 7.7% of individuals with PRDM16 not deleted (P=0.1). In the combined retrospective and systematic review cohort (n=134), PRDM16 deletion-associated cardiomyopathy risk was recapitulated and significant (29.1% versus 10.8%, P=0.03). PRDM16 deletion was associated with increased risk of death, cardiac transplant, or ventricular assist device (P=0.04). Among those PRDM16 deleted, 34.5% of females developed cardiomyopathy versus 16.7% of their male counterparts (P=0.2). We find sex-specific differences in the incidence and the severity of contractile dysfunction and fibrosis in female Prdm16 conditional knockout mice. Further, female Prdm16 conditional knockout mice demonstrate significantly elevated risk of mortality (P=0.0003). CONCLUSIONS: PRDM16 deletion is associated with a significantly increased risk of cardiomyopathy and cardiac mortality. Prdm16 conditional knockout mice develop cardiomyopathy in a sex-biased way. Patients with PRDM16 deletion should be assessed for cardiac disease.

Cardiovascular Manifestations of Turner Syndrome: Phenotypic Differences Between Karyotype Subtypes.

Turner syndrome (TS) is a genetic disorder presenting in phenotypic females with total or partial monosomy of the X chromosome. Cardiovascular abnormalities are common, including congenital heart defects (CHD) and aortic dilation. Although mosaic TS is suspected to have less severe phenotype as compared to non-mosaic TS, differences in cardiovascular manifestations between karyotypes are not well studied. This is a single-center retrospective cohort study including patients with TS seen from 2000 to 2022. Demographic data, chromosomal analysis, and imaging were reviewed. Karyotypes were categorized as monosomy X (45X), 45X mosaicism, isochromosome Xq, partial X deletions, ring X (r(X)), TS with Y material, and others. Prevalence of CHD and aortic dilation were compared between monosomy X and other subtypes using Pearson's chi-square test and Welch two-sample t-test. We included 182 TS patients with median age 18 (range 4-33) years. CHD was more common in monosomy X as compared with others (61.4% vs. 26.8%, p < 0.001), including bicuspid aortic valve (44.3% vs. 16.1%, p < 0.001), partial anomalous pulmonary venous return (12.9% vs. 2.7%, p = 0.023), persistent left superior vena cava (12.9% vs. 1.8%, p = 0.008), and coarctation of the aorta (20.0% vs. 4.5%, p = 0.003). Cardiac surgery (24.3% vs. 8.9%, p = 0.017) was more prevalent in the monosomy X group. There was no statistically significant difference for presence of aortic dilation (7.1% vs 1.8%, p = 0.187). Although CHD and need for cardiac surgery are more common in TS with monosomy X as compared to others, all TS subtypes may have similar risk of developing aortic dilation. All TS patients should have similar cardiovascular surveillance testing to monitor for aortic dilation.

Multiple mitochondrial dysfunctions syndrome 1: An unusual cause of developmental pulmonary hypertension.

Pulmonary hypertension (pHTN) is a severe, life-threatening disease, which can be idiopathic or associated with an underlying syndrome or genetic diagnosis. Here we discuss a patient who presented with severe pHTN and was later found to be compound heterozygous for pathogenic variants in the NFU1 gene causing multiple mitochondrial dysfunctions syndrome 1 (MMDS1). Review of autopsy slides from an older sibling revealed the same diagnosis along with pulmonary findings consistent with a developmental lung disorder. In particular, these postmortem, autopsy findings have not been described previously in humans with this mitochondrial syndrome and suggest a possible developmental basis for the severe pHTN seen in this disease. Given the rarity of patients reported with MMDS1, we review the current state of knowledge of this disease and our novel management strategies for pHTN and MMDS1-associated complications in this population.

Swimming bacteria promote dispersal of non-motile staphylococcal species.

Swimming motility is considered a beneficial trait among bacterial species as it enables movement across fluid environments and augments invasion of tissues within the host. However, non-swimming bacteria also flourish in fluid habitats, but how they effectively spread and colonize distant ecological niches remains unclear. We show that non-motile staphylococci can gain motility by hitchhiking on swimming bacteria, leading to extended and directed motion with increased velocity. This phoretic interaction was observed between Staphylococcus aureus and Pseudomonas aeruginosa, Staphylococcus epidermidis and P. aeruginosa, as well as S. aureus and Escherichia coli, suggesting hitchhiking as a general translocation mechanism for non-motile staphylococcal species. By leveraging the motility of swimming bacteria, it was observed that staphylococci can colonize new niches that are less available in the absence of swimming carriers. This work highlights the importance of considering interactions between species within polymicrobial communities, in which bacteria can utilize each other as resources.

Material properties of biofilms-a review of methods for understanding permeability and mechanics.

Microorganisms can form biofilms, which are multicellular communities surrounded by a hydrated extracellular matrix of polymers. Central properties of the biofilm are governed by this extracellular matrix, which provides mechanical stability to the 3D biofilm structure, regulates the ability of the biofilm to adhere to surfaces, and determines the ability of the biofilm to adsorb gases, solutes, and foreign cells. Despite their critical relevance for understanding and eliminating of biofilms, the materials properties of the extracellular matrix are understudied. Here, we offer the reader a guide to current technologies that can be utilized to specifically assess the permeability and mechanical properties of the biofilm matrix and its interacting components. In particular, we highlight technological advances in instrumentation and interactions between multiple disciplines that have broadened the spectrum of methods available to conduct these studies. We review pioneering work that furthers our understanding of the material properties of biofilms.

Single particle tracking reveals spatial and dynamic organization of the E. coli biofilm matrix.

Biofilms are communities of surface-adherent bacteria surrounded by secreted polymers known as the extracellular polymeric substance (EPS). Biofilms are harmful in many industries, and thus it is of great interest to understand their mechanical properties and structure to determine ways to destabilize them. By performing single particle tracking with beads of varying surface functionalization it was found that charge interactions play a key role in mediating mobility within biofilms. With a combination of single particle tracking and microrheological concepts, it was found that Escherichia coli biofilms display height dependent charge density that evolves over time. Statistical analyses of bead trajectories and confocal microscopy showed inter-connecting micron scale channels that penetrate throughout the biofilm, which may be important for nutrient transfer through the system. This methodology provides significant insight into a particular biofilm system and can be applied to many others to provide comparisons of biofilm structure. The elucidation of structure provides evidence for the permeability of biofilms to microscale objects, and the ability of a biofilm to mature and change properties over time.

Functional delivery of siRNA in mice using dendriworms.

Small interfering RNAs (siRNAs) mediate cleavage of specific, complementary mRNA sequences and thus regulate gene expression. Not surprisingly, their use for treatment of diseases that are rooted in aberrant gene expression, such as cancer, has become a paradigm that has gained wide interest. Here, we report the development of dendrimer-conjugated magnetofluorescent nanoworms that we call "dendriworms" as a modular platform for siRNA delivery in vivo. This platform maximizes endosomal escape to robustly produce protein target knockdown in vivo, and is tolerated well in mouse brain. We demonstrate that siRNA-carrying dendriworms can be readily internalized by cells and enable endosomal escape across a wide range of loading doses, whereas dendrimers or nanoworms alone are inefficient. Further, we show that dendriworms carrying siRNA against the epidermal growth factor receptor (EGFR) reduce protein levels of EGFR in human glioblastoma cells by 70-80%, 2.5-fold more efficiently than commercial cationic lipids. Dendriworms were well-tolerated after 7-days of convection-enhanced delivery to the mouse brain and in an EGFR-driven transgenic model of glioblastoma, anti- EGFR dendriworms led to specific and significant suppression of EGFR expression. Collectively, these data establish dendriworms as a multimodal platform that enables fluorescent tracking of siRNA delivery in vivo, cellular entry, endosomal escape, and knockdown of target proteins.