The elastic properties of renal glomeruli and their capillaries permit them to maintain structural integrity in the presence of variable hemodynamic forces. Measured by micro-indentation, glomeruli have an elastic modulus (E, Young’s modulus) of 2.1 kPa, and estimates from glomerular perfusion studies suggest that the E of glomeruli is between 2 and 4 kPa. F-actin depolymerization by latrunculin, inhibition of acto-myosin contractility by blebbistatin, reduction in ATP synthesis, and reduction of the affinity of adhesion proteins by EDTA reduced the glomerular E to 1.26, 1.7, 1.5, and 1.43 kPa, respectively. Actin filament stabilization with jasplakinolide and increasing integrin affinity with Mg2+ increased E to 2.65 and 2.87 kPa, respectively. Alterations in glomerular E are reflected in commensurate changes in F/G actin ratios. Disruption of vimentin intermediate filaments by withaferin A reduced E to 0.92 kPa. The E of decellularized glomeruli was 0.74 kPa, indicating that cellular components of glomeruli have dominant effects on their elasticity. The E of glomerular basement membranes measured by magnetic bead displacement was 2.4 kPa. Podocytes and mesangial cells grown on substrates with E values between 3 and 5 kPa had actin fibers and focal adhesions resembling those of podocytes in vivo. Renal ischemia and ischemia-reperfusion reduced the E of glomeruli to 1.58 kPa. These results show that the E of glomeruli is between 2 and 4 kPa. E of the GBM, 2.4 kPa, is consistent with this value, and is supported by the behavior of podocytes and mesangial cells grown on variable stiffness matrices. The podocyte cytoskeleton contributes the major component to the overall E of glomeruli, and a normal E requires ATP synthesis. The reduction in glomerular E following ischemia and in other diseases indicates that reduced glomerular E is a common feature of many forms of glomerular injury and indicative of an abnormal podocyte cytoskeleton.

No abstract

extended early antibiotic exposure in the neonatal intensive care unit is associated with an increased risk for the development of late-onset sepsis (LoS). However, few studies have examined the mechanisms involved. We sought to determine how the neonatal microbiome and intestinal immune response is altered by transient early empiric antibiotic exposure at birth. neonatal mice were transiently exposed to broad-spectrum antibiotics from birth for either 3-(SE) or 7-days (LE) and were examined at 14-days-old. We found that mice exposed to either SE or LE showed persistent expansion of Proteobacteria (2 log difference, P < 0.01). Further, LE mice demonstrated baseline translocation of E. coli into the liver and spleen and were more susceptible K. pneumoniae-induced sepsis. Le mice had a significant and persistent decrease in type 3 innate lymphoid cells (ILC3) in the lamina propria. Reconstitution of the microbiome with mature microbiota by gavage in Le mice following antibiotic exposure resulted in an increase in ILC3 and partial rescue from LOS. We conclude that prolonged exposure to broad spectrum antibiotics in the neonatal period is associated with persistent alteration of the microbiome and innate immune response resulting in increased susceptibility to infection that may be partially rescued by microbiome reconstitution. Seventy five percent of preterm babies admitted to the neonatal intensive care unit (NICU) receive antibiotics empirically 1,2. Empiric antibiotics are generally broad-spectrum and prescribed based on risk assessment and not direct evidence of infection. The majority of infants in the NICU are exposed to transient antibiotics from birth that ranges from 2 to 7 days. Prolonged empiric antibiotics, lasting more than 2 days, are administered to approximately 35% to 50% of infants with a low gestational age 3. Many babies born prematurely are also exposed to antibiotics in utero just prior to birth. Several clinical studies have demonstrated that exposure to transient early antibiotics in the NICU can increase the risk for development of late-onset sepsis (LOS) 1,2,4,5. LOS is an important cause of morbidity and mortality in the NICU 5,6. Alteration of the intestinal microbiome and innate immune response may play an important role in increasing the risk for LOS in preterm infants. Early normal bacterial colonization is important for normal development of the gut 7 : strengthening and promoting gut barrier integrity 8,9 , protecting against pathogens 10 and regulating host immunity 11-13. Establishment of the microbiome during the neonatal period depends on multiple factors, including mode of delivery, breast versus formula feeding, gestational age, infant hospitalization, maternal diet and antibiotic use by the infant 14,15. While antibiotics are beneficial for treating human bacterial infections, even

No abstract

No abstract