The complexity of extracellular vesicles: Bridging the gap between cellular communication and neuropathology.

Brain-derived extracellular vesicles (EVs) serve a prominent role in maintaining homeostasis and contributing to pathology in health and disease. This review establishes a crucial link between physiological processes leading to EV biogenesis and their impacts on disease. EVs are involved in the clearance and transport of proteins and nucleic acids, responding to changes in cellular processes associated with neurodegeneration, including autophagic disruption, organellar dysfunction, aging, and other cell stresses. In neurodegenerative disorders (e.g., Alzheimer's disease, Parkinson's disease, etc.), EVs contribute to the spread of pathological proteins like amyloid ß, tau, ɑ-synuclein, prions, and TDP-43, exacerbating neurodegeneration and accelerating disease progression. Despite evidence for both neuropathological and neuroprotective effects of EVs, the mechanistic switch between their physiological and pathological functions remains elusive, warranting further research into their involvement in neurodegenerative disease. Moreover, owing to their innate ability to traverse the blood-brain barrier and their ubiquitous nature, EVs emerge as promising candidates for novel diagnostic and therapeutic strategies. The review uniquely positions itself at the intersection of EV cell biology, neurophysiology, and neuropathology, offering insights into the diverse biological roles of EVs in health and disease.

Ion permeation pathway within the internal pore of P2X receptor channels.

P2X receptor channels are trimeric ATP-activated ion channels expressed in neuronal and non-neuronal cells that are attractive therapeutic targets for human disorders. Seven subtypes of P2X receptor channels have been identified in mammals that can form both homomeric and heteromeric channels. P2X1-4 and P2X7 receptor channels are cation-selective, whereas P2X5 has been reported to have both cation and anion permeability. P2X receptor channel structures reveal that each subunit is comprised of two transmembrane helices, with both N-and C-termini on the intracellular side of the membrane and a large extracellular domain that contains the ATP binding sites at subunit interfaces. Recent structures of ATP-bound P2X receptors with the activation gate open reveal the unanticipated presence of a cytoplasmic cap over the central ion permeation pathway, leaving lateral fenestrations that may be largely buried within the membrane as potential pathways for ions to permeate the intracellular end of the pore. In the present study, we identify a critical residue within the intracellular lateral fenestrations that is readily accessible to thiol-reactive compounds from both sides of the membrane and where substitutions influence the relative permeability of the channel to cations and anions. Taken together, our results demonstrate that ions can enter or exit the internal pore through lateral fenestrations that play a critical role in determining the ion selectivity of P2X receptor channels.

A Systematic Review of Longitudinal Risk and Protective Factors and Correlates for Posttraumatic Stress and Its Natural History in Forcibly Displaced Children.

BACKGROUND: Posttraumatic stress (PTS) results in significant distress or functional impairment. Prevalence studies report higher rates of PTS in forcibly displaced children (FDC). Current evidence deriving mainly from cross-sectional studies is unable to make causal attributions. Given rising rates of forcible displacement reported by the United Nations High Commissioner for Refugees (UNHCR) in 2014, there is increasing need to determine the best policies and practice for engaging mental health needs of FDC. METHODS: This systematic review identifies (1) longitudinal risk and protective factors and correlates for PTS and (2) its natural history in FDC, contributing to research identifying vulnerable subgroups and malleable factors for PTS and understanding its natural history. No meta-analysis was conducted due to heterogeneity; results were analyzed through narrative synthesis. RESULTS: Eleven longitudinal studies were identified. All but one were prospective cohort designs. They identified prevalence rates between 20% and 48.7% at baseline, 10% and 48.3% at 1 year ( k = 7), 18% and 48% at 2-3 years ( k = 2), 8% and 38% at 6 years ( k = 2), and 35% at 12 years using nine measurement methods in seven independent samples. Evidence from multiple associations supported the following risk factors: exposure to traumatic stressors or other stress, older age, and prior psychopathology. Evidence predominantly supported the stability of PTS with some decline. CONCLUSION: While results should be interpreted with caution given small or unrepresentative samples, they suggest regular mental health screenings should be conducted for FDC, who are a vulnerable subgroup with variable onset and remission. Risk associations with prior psychopathology also suggest that screening upon arrival may be advisable for early intervention and prevention.

Urinary tract abnormalities in boys with recurrent urinary tract infections after hypospadias repair.

OBJECTIVE: To examine the development of recurrent urinary tract infections (UTIs) in boys who have undergone hypospadias repair. MATERIALS AND METHODS: We retrospectively reviewed the records of all boys who had recurrent UTIs after primary or redo tubularized incised plate (TIP) or transverse island flap (TVIF) repairs, between 1998 and 2009. Data on age, operating details, postoperative complications and imaging studies were collected. We attempted to identify risk factors for recurrent UTIs after hypospadias repair. RESULTS: During the study period, 43/2249 boys (1.91%) were diagnosed with recurrent UTIs after hypospadias repair. The boys' mean (range) age at repair was 14 (6-24) months and the median (range) follow-up was 6.5 (1.5-11) years. Primary TIP and TVIF were performed in 47% (20/43) and 35% (15/43) of the boys, respectively. Redo surgeries were performed in 18% of the boys (8/43). The initial meatal location was proximal in all TVIF and redo repairs, and in one of the TIP repairs. Postoperative voiding cysto-urethrography, ultrasonography and dimercapto-succinic acid (DMSA) scans were performed in 58% (25/43), 90% (39/43) and 19% (8/43) of the boys, respectively. Abnormalities were noted. Of those boys who underwent a TVIF repair, urethral diverticula were seen in 47% (7/15) and urethral fistulae were also seen in 47% (7/15). Conversely, in those who had a TIP repair, an elevated PVR and vesico-ureteric reflux were more common; they were found in 40% (8/20) and 50% (10/20) of patients, respectively. CONCLUSIONS: The pathophysiology of recurrent UTI is multifactorial, but postoperative complications seem to vary with type of procedure. Recurrent UTIs after hypospadias surgery should prompt a specific assessment for potentially functionally relevant and correctable anatomical abnormalities.

Association between germline HOXB13 G84E mutation and risk of prostate cancer.

Recently, a G84E mutation in HOXB13, a gene involved in prostate development, was shown to be strongly associated with an increased risk of prostate cancer. To confirm this association in a screening setting, we conducted a case-control study and sequenced germline DNA from peripheral leukocytes of 1843 men diagnosed with prostate cancer (case subjects) and 2225 men without prostate cancer (control subjects) for mutations in HOXB13. Subjects (aged 40-94 years) were prescreened and underwent a prostate biopsy at two tertiary care centers in Canada. The frequency of HOXB13 variants was determined in case subjects and control subjects by race, and odds ratios and 95% confidence intervals were based on 2×2 table analysis. All statistical tests were two-sided. Twelve men of white race were identified to be carriers of the G84E mutation. The G84E mutation was more frequent among white case subjects than among white control subjects (10 of 1525 [0.7%] vs 2 of 1757 [0.1%], P = .01) and was associated with an increased risk of prostate cancer (unadjusted odds ratio = 5.8, 95% confidence interval = 1.3 to 26.5, P = .01).

Type IV collagen induces podocytic features in bone marrow stromal stem cells in vitro.

Bone marrow-derived stromal stem cells (BMSC) can differentiate along a variety of mesenchymal lines, including mesangial cells. For determining whether BMSC can be induced to differentiate along podocytic lines in vitro, canine BMSC were cultured on plastic, type I collagen, and NC1 hexamers of type IV collagen from normal and Alport canine glomerular basement membrane. Results were compared with a mouse podocyte cell line. In the case of the podocyte line, differentiation occurred on all three matrices as indicated by the expression of synaptopodin and CD2-associated protein (CD2AP) and organization of myosin heavy chain IIA into a linear pattern. BMSC proliferated equally well on all matrices, but cells that were grown on type IV collagen NC1 hexamers became larger and stellate. Evidence for podocytic differentiation occurred on all three collagen matrices as indicated by the redistribution of myosin IIA to a linear pattern and expression of synaptopodin, CD2AP, and alpha-actinin. A punctate distribution of CD2AP was seen only in cells that were grown on normal and Alport glomerular basement membrane NC1 hexamers. Differentiated podocytes expressed the alpha1, alpha2, and alpha5 chains of type IV collagen but at higher levels in cells that were grown on NC1 hexamers. Similar results were obtained in BMSC for the alpha1 and alpha2 chains only. The alpha3, alpha4, and alpha6 chains were never detected in the podocyte line or BMSC. These results indicate that BMSC undergo a degree of podocytic differentiation in vitro and greater when grown on type IV collagen NC1 hexamers than type I collagen. Alport and normal NC1 hexamers seem equally permissive to BMSC growth and differentiation, suggesting that these processes are not influenced specifically by the alpha3/alpha4/alpha5 network. BMSC may be useful in the development of stem cell-based reconstitution of glomeruli that are damaged by disease and for gene therapy of genetic glomerular diseases such as Alport syndrome.

DDR1-deficient mice show localized subepithelial GBM thickening with focal loss of slit diaphragms and proteinuria.

BACKGROUND: Type IV collagen in basement membranes is a ligand for the receptor tyrosine kinase discoidin domain receptor 1 (DDR1). DDR1 is expressed in renal cells and regulates cell adhesion and proliferation ex vivo. The interaction between type IV collagen and cell surface receptors is believed important for normal renal function as well as significant in chronic renal diseases and we therefore analyzed mice with a targeted deletion of DDR1. METHODS: Homozygous DDR1 knockout mice were compared to heterozygous and wild-type animals. The quantitative and qualitative amount of proteinuria was measured by urine-microelectrophoresis. Structural changes of the kidneys were determined by immunohistochemistry, light microscopy, and electron microscopy. RESULTS: Compared to heterozygous littermates, adult DDR1 knockout mice showed a selective middle- to high-molecular proteinuria of up to 0.3 g/L and urinary acanthocytes. There was no evidence of uremia with no change in serum urea in the first 9 months of age. Little apparent change in renal morphology was detected using light microscopy. However, electron microscopy showed a localized, subepithelial, mushroom-like isodense thickening of the glomerular basement membrane (GBM). Within these areas, a focal loss of the podocytic slit diaphragms occurred. CONCLUSION: The loss of cell-matrix communication in DDR1-deficient podocytes appears to result in excess synthesis of basement membrane proteins leading to disturbed anchorage of foot processes and disruption of the slit diaphragm. Our data suggest that the interaction between type IV collagen and DDR1 plays an important role in maintaining the structural integrity of the GBM.