Glomerular Elasticity and Gene Expression Patterns Define Two Phases of Alport Nephropathy.

Rationale: We take a unique approach to understanding the causes of podocyte injury in collagen IV nephropathies, a crucial step in developing targeted therapies for conditions like Alport Syndrome. Objectives: We characterize the structural, functional, and biophysical properties of glomerular capillaries and podocytes in Col4α3 -/- mice and analyze kidney cortex transcriptional profiles at various disease stages. We investigate the effects of the ER stress mitigator TUDCA on these parameters. Furthermore, we used human FSGS associated podocyte enriched genes to identify molecular pathways rescued by TUDCA thereby offering potential therapeutic targets for Alport Syndrome. Findings: We find a clear disease progression timeline in Col4α3 -/- mice. Podocyte injury develops by 3 months, with glomeruli reaching maximum deformability at 4 months, associated with a 40% loss of podocytes. This is followed by progressive stiffening of glomerular capillaries, increasing proteinuria, reduced renal function, inflammatory infiltrates, and fibrosis from months 4 to 8. Bulk RNA sequencing at 2, 4, and 7 months reveals a progressive increase in expression of genes related to cytokine and chemokine signaling, matrix and cell injury, and activation of the TNF pathway, similar to observations in a NEPTUNE FSGS cohort. Podocyte-enriched genes from FSGS patients mapped to mice found that TUDCA, which mitigated glomerular and renal injury suppressed molecular pathways associated with extracellular matrix and basement membrane synthesis, podocyte stress and hypertrophy. Conclusions: We uncover two distinct phases of Col4α3 -/- nephropathy progression. The first is characterized by podocytopathy, increased glomerular capillary deformability and accelerated podocyte loss, and the second by increased capillary wall stiffening and renal inflammatory and profibrotic pathway activation. The response of podocytes to TUDCA treatment provides novel insights into downstream signaling pathways, offering potential therapeutic targets for treating Alport and related nephropathies.

Staphylococcus aureus isolates from children with clinically differentiated osteomyelitis exhibit distinct transcriptomic signatures.

There is substantial genomic heterogeneity among Staphylococcus aureus isolates of children with acute hematogenous osteomyelitis (AHO) but transcriptional behavior of clinically differentiated strains has not been previously described. This study evaluates transcriptional activity of S. aureus isolates of children with AHO that may regulate metabolism, biosynthesis, or virulence during bacterial growth and pathogenesis. In vitro growth kinetics were compared between three S. aureus clinical isolates from children with AHO who had mild, moderate, and severe illness. Total RNA sequencing was performed for each isolate at six separate time points throughout the logarithmic phase of growth. The NASA RNA-Sequencing Consensus Pipeline was used to identify differentially expressed genes allowing for 54 comparisons between the three isolates during growth. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment pathways were used to evaluate transcriptional variation in metabolism, biosynthesis pathways and virulence potential of the isolates. The S. aureus isolates demonstrated differing growth kinetics under standardized conditions with the mild isolate having higher optical densities with earlier and higher peak rates of growth than that of the other isolates (p<0.001). Enrichment pathway analysis established distinct transcriptional signatures according to both sampling time and clinical severity. Moderate and severe isolates demonstrated pathways of bacterial invasion, S. aureus infection, quorum sensing and two component systems. In comparison, the mild strain favored biosynthesis and metabolism. These findings suggest that transcriptional regulation during the growth of S. aureus may impact the pathogenetic mechanisms involved in the progression of severity of illness in childhood osteomyelitis. The clinical isolates studied demonstrated a tradeoff between growth and virulence. Further investigation is needed to evaluate these transcriptional pathways in an animal model or during active clinical infections of children with AHO.

"Spot and hop": internal referencing for surface plasmon resonance imaging using a three-dimensional microfluidic flow cell array.

We have developed a novel referencing technique for surface plasmon resonance imaging systems referred to as "spot and hop." The technique enables internal referencing for individual flow cells in a parallel processing microfluidic network. Internal referencing provides the ability to correct for nonspecific binding and instrument drift, significantly improving data quality at each region of interest. The performance of a 48-flow-cell device was demonstrated through a series of studies, including "rise and fall" time, ligand preconcentration, ligand immobilization, analyte binding, and regeneration tests. Interfacing parallel processing fluidics with imaging systems will significantly expand the throughput and applications of array-based optical biosensors while retaining high data quality.