Caspase-1 inhibition improves cognition without significantly altering amyloid and inflammation in aged Alzheimer disease mice.

Human genetic and animal model studies indicate that brain microglial inflammation is a primary driver of cognitive impairment in Alzheimer Disease (AD). Inflammasome-activated Caspase-1 (Casp1) is associated with both AD microglial inflammation and neuronal degeneration. In mice, Casp1 genetic ablation or VX-765 small molecule inhibition of Casp1 given at onset of cognitive deficits strongly supports the association between microglial inflammation and cognitive impairment. Here, VX-765 significantly improved episodic and spatial memory impairment eight months after the onset of cognitive impairment in aged AD mice with significant amyloid beta peptide (Aß) accumulation and microglial inflammation. Unexpectedly, while cognitive improvement was associated with dendritic spine density and hippocampal synaptophysin level recovery, VX-765 only slightly decreased Aß deposition and did not alter biochemically-measured Aß levels. Furthermore, increased hippocampal Iba1+-microglia, GFAP+-astrocytes, IL-1ß, and TNF-α levels were unaltered by VX-765. These results support the hypothesis that neuronal degeneration, not Aß or microglial inflammation, drives cognitive impairment in AD.

Therapeutic potential of Nlrp1 inflammasome, Caspase-1, or Caspase-6 against Alzheimer disease cognitive impairment.

The sequential activation of Nucleotide-binding oligomerization domain, Leucine rich Repeat and Pyrin domain containing protein 1 (Nlrp1) inflammasome, Caspase-1 (Casp1), and Caspase-6 (Casp6) is implicated in primary human neuron cultures and Alzheimer Disease (AD) neurodegeneration. To validate the Nlrp1-Casp1-Casp6 pathway in vivo, the APPSwedish/Indiana J20 AD transgenic mouse model was generated on either a Nlrp1, Casp1 or Casp6 null genetic background and mice were studied at 4-5 months of age. Episodic memory deficits assessed with novel object recognition were normalized by genetic ablation of Nlrp1, Casp1, or Casp6 in J20 mice. Spatial learning deficits, assessed with the Barnes Maze, were normalized in genetically ablated J20, whereas memory recall was normalized in J20/Casp1-/- and J20/Casp6-/-, and improved in J20/Nlrp1-/- mice. Hippocampal CA1 dendritic spine density of the mushroom subtype was reduced in J20, and normalized in genetically ablated J20 mice. Reduced J20 hippocampal dentate gyrus and CA3 synaptophysin levels were normalized in genetically ablated J20. Increased Iba1+-microglia in the hippocampus and cortex of J20 brains were normalized by Casp1 and Casp6 ablation and reduced by Nlrp1 ablation. Increased pro-inflammatory cytokines, TNF-α and CXCL1, in the J20 hippocampus were normalized by Nlrp1 or Casp1 genetic ablation. CXCL1 was also normalized by Casp6 genetic ablation. IFN-γ was increased and total amyloid ß peptide was decreased in genetically ablated Nlrp1, Casp1 or Casp6 J20 hippocampi. We conclude that Nlrp1, Casp1, or Casp6 are implicated in AD-related cognitive impairment, inflammation, and amyloidogenesis. These results indicate that Nlrp1, Casp1, and Casp6 represent rational therapeutic targets against cognitive impairment and inflammation in AD.

Children with vesicoureteric reflux have joint hypermobility and occasional tenascin XB sequence variants.

INTRODUCTION: To consider alternative mechanisms that give rise to a refluxing ureterovesical junction (UVJ), we hypothesized that children with a common heritable urinary tract defect, vesicoureteric reflux (VUR), may have a defect in the extracellular matrix composition of the UVJ and other tissues that would be revealed by assessment of the peripheral joints. Hypermobile joints can arise from defects in the extracellular matrix within the joint capsule that affect proteins, including tenascin XB (TNXB). METHODS: We performed an observational study of children with familial and non-familial VUR to determine the prevalence of joint hypermobility, renal scarring, and DNA sequence variants in TNXB. RESULTS: Most children (27/44) exhibited joint hypermobility using the Beighton scoring system. This included 15/26 girls (57.7%) and 12/18 boys (66.7%), which is a significantly higher prevalence for both sexes when compared to population controls (p<0.005). We found no association between joint hypermobility and renal scarring. Seven of 49 children harbored rare pathogenic sequence variants in TNXB, and two also exhibited joint hypermobility. No sequence variants in TNXB were identified in 25/27 children with VUR and joint hypermobility. Due to the observational design of the study, there was missing data for joint hypermobility scores in six children and for dimercaptosuccinic acid (DMSA) scans in 17 children. CONCLUSIONS: We observed a high prevalence of VUR and joint hypermobility in children followed within a tertiary care pediatric urology clinic. While mutations in TNXB have been reported in families with VUR and joint hypermobility, we identified only two children with these phenotypes and pathogenic variants in TNXB. We, therefore, speculate that VUR and joint hypermobility may be due to mutations in other extracellular matrix genes.

Heterozygous loss-of-function mutation in Odd-skipped related 1 (Osr1) is associated with vesicoureteric reflux, duplex systems, and hydronephrosis.

Odd-skipped related 1 (Osr1) is a transcriptional repressor that plays critical roles in maintaining the mesenchymal stem cell population within the developing kidney. Here, we report that newborn pups with a heterozygous null mutation in Osr1 exhibit a 21% incidence of vesicoureteric reflux and have hydronephrosis and urinary tract duplications. Newborn pups have a short intravesical ureter, resulting in a less competent ureterovesical junction which arises from a delay in urinary tract development. We describe a new domain of Osr1 expression in the ureteral mesenchyme and within the developing bladder in the mouse. OSR1 was sequenced in 186 children with primary vesicoureteric reflux, and 17 have single nucleotide polymorphisms. Fifteen children have a common synonymous variant, rs12329305, one child has a rare nonsynonymous variant, rs3440471, and one child has a rare 5'-UTR variant, rs45535040 The impact of these SNPs is not clear; therefore, the role of OSR1 in human disease remains to be elucidated. Osr1 is a candidate gene implicated in the pathogenesis of vesicoureteric reflux and congenital abnormalities of the kidney and urinary tract in mice.

Vesicoureteric reflux and reflux nephropathy: from mouse models to childhood disease.

Vesicoureteric reflux (VUR) is a common congenital urinary tract defect that predisposes children to recurrent kidney infections. Kidney infections can result in renal scarring or reflux nephropathy defined by the presence of chronic tubulo-interstitial inflammation and fibrosis that is a frequent cause of end-stage renal failure. The discovery of mouse models with VUR and with reflux nephropathy has provided new opportunities to understand the pathogenesis of these conditions and may provide insight on the genes and the associated phenotypes that need to be examined in human studies.