Caspase-9 inhibition confers stronger neuronal and vascular protection compared to VEGF neutralization in a mouse model of retinal vein occlusion

PurposeRetinal vein occlusion (RVO) is a sight-threatening condition typically treated with intravitreal injection of vascular endothelial growth factor (VEGF) antagonists. Treatment response to anti-VEGF therapies is highly variable, with poor visual outcomes and treatment response in patients with significant retinal nonperfusion following RVO. Recently, caspase-9 has been identified as a potent regulator of edema, gliosis, and neuronal dysfunction during acute retinal hypoxia. The purpose of this study was to compare the therapeutic effect of caspase-9 inhibition against VEGF-neutralization in an established mouse model of RVO.MethodsAdult male C57Bl/6 J mice were randomized to induction of RVO and treatment with either vehicle, intravitreal injection of anti-VEGF antibody, topical administration of a selective caspase-9 inhibitor (Pen1-XBir3), or a combination therapy. Animals were followed on days 1, 2, and 8 after RVO with fundus retinal imaging, and with optical coherence tomography (OCT) to capture retinal swelling, capillary nonperfusion (measured by disorganization of retinal inner layers, DRIL), hyperreflective foci (HRF), and retinal atrophy. Focal electroretinography (ERG) measurements were performed on day 7. Histology was performed on retinal sections from day 8.ResultsBoth VEGF neutralization and caspase-9 inhibition showed significant retinal protection from RVO compared to vehicle treatment arm. Retinal reperfusion of occluded veins was accelerated in eyes receiving caspase-9 inhibitor, but not significantly different from vehicle in the anti-VEGF group. Retinal edema was suppressed in all treatment groups, with approximately 2-fold greater edema reduction with caspase-9 inhibition compared to VEGF neutralization. HRF were reduced similarly across all treatment groups compared to vehicle. Retinal detachment was reduced only in eyes treated with caspase-9 inhibitor monotherapy. Caspase-9 inhibition reduced retinal atrophy and preserved ERG response; VEGF neutralization did not prevent neurodegeneration following RVO.ConclusionCaspase-9 inhibition confers stronger neuronal and vascular protection compared to VEGF neutralization in the mouse laser-induced model of RVO

Mutations in CRADD Result in Reduced Caspase-2-Mediated Neuronal Apoptosis and Cause Megalencephaly with a Rare Lissencephaly Variant.

Lissencephaly is a malformation of cortical development typically caused by deficient neuronal migration resulting in cortical thickening and reduced gyration. Here we describe a "thin" lissencephaly (TLIS) variant characterized by megalencephaly, frontal predominant pachygyria, intellectual disability, and seizures. Trio-based whole-exome sequencing and targeted re-sequencing identified recessive mutations of CRADD in six individuals with TLIS from four unrelated families of diverse ethnic backgrounds. CRADD (also known as RAIDD) is a death-domain-containing adaptor protein that oligomerizes with PIDD and caspase-2 to initiate apoptosis. TLIS variants cluster in the CRADD death domain, a platform for interaction with other death-domain-containing proteins including PIDD. Although caspase-2 is expressed in the developing mammalian brain, little is known about its role in cortical development. CRADD/caspase-2 signaling is implicated in neurotrophic factor withdrawal- and amyloid-β-induced dendritic spine collapse and neuronal apoptosis, suggesting a role in cortical sculpting and plasticity. TLIS-associated CRADD variants do not disrupt interactions with caspase-2 or PIDD in co-immunoprecipitation assays, but still abolish CRADD's ability to activate caspase-2, resulting in reduced neuronal apoptosis in vitro. Homozygous Cradd knockout mice display megalencephaly and seizures without obvious defects in cortical lamination, supporting a role for CRADD/caspase-2 signaling in mammalian brain development. Megalencephaly and lissencephaly associated with defective programmed cell death from loss of CRADD function in humans implicate reduced apoptosis as an important pathophysiological mechanism of cortical malformation. Our data suggest that CRADD/caspase-2 signaling is critical for normal gyration of the developing human neocortex and for normal cognitive ability

Independent chromatin binding of ARGONAUTE4 and SPT5L/KTF1 mediates transcriptional gene silencing.

Eukaryotic genomes contain significant amounts of transposons and repetitive DNA elements, which, if transcribed, can be detrimental to the organism. Expression of these elements is suppressed by establishment of repressive chromatin modifications. In Arabidopsis thaliana, they are silenced by the siRNA-mediated transcriptional gene silencing pathway where long non-coding RNAs (lncRNAs) produced by RNA Polymerase V (Pol V) guide ARGONAUTE4 (AGO4) to chromatin and attract enzymes that establish repressive chromatin modifications. It is unknown how chromatin modifying enzymes are recruited to chromatin. We show through chromatin immunoprecipitation (ChIP) that SPT5L/KTF1, a silencing factor and a homolog of SPT5 elongation factors, binds chromatin at loci subject to transcriptional silencing. Chromatin binding of SPT5L/KTF1 occurs downstream of RNA Polymerase V, but independently from the presence of 24-nt siRNA. We also show that SPT5L/KTF1 and AGO4 are recruited to chromatin in parallel and independently of each other. As shown using methylation-sensitive restriction enzymes, binding of both AGO4 and SPT5L/KTF1 is required for DNA methylation and repressive histone modifications of several loci. We propose that the coordinate binding of SPT5L and AGO4 creates a platform for direct or indirect recruitment of chromatin modifying enzymes

A cross‐sectional study comparing the inflammatory profile of menstrual effluent vs. peripheral blood

Abstract Background and Aims Cytokine profiles of peripheral blood and other bodily fluids provide diagnostic indicators for assessing inflammatory processes. Menstrual effluent may provide a noninvasive source of biological material for monitoring cytokine levels in blood and in endometrial tissues. This pilot study investigated the potential of measuring cytokines in menstrual effluent, and compared the cytokine profiles of menstrual versus peripheral blood. Methods Seven healthy donors (aged ≥18 and ≤45 years) collected menstrual effluent on day 2 of menses. Matched peripheral blood samples were collected by venous blood draw on the same day. Levels of 62 cytokines were measured in all samples by 62‐plex Luminex assay. Results Peripheral blood and menstrual effluent cytokine profiles were tenuously correlated (r2 = 0.26, p  0.05) for 53/62 cytokines in menstrual effluent versus peripheral blood. Levels of TGF‐β (r2 = 0.87, p = 0.002) and CCL7 (r2 = 0.63, p = 0.033) were significantly positively correlated between matched menstrual and peripheral blood samples. Conclusion In this group of study participants, the cytokine profile of menstrual effluent was quantitatively distinct from peripheral blood, and also characterized by higher levels of inflammatory signaling. This pattern of comparative menstrual blood cytokine profiles points to a need for further studies to evaluate the relationship between peripheral and menstrual blood cytokines in broader populations including both healthy and diseased states

Endothelial activation of caspase-9 promotes neurovascular injury in retinal vein occlusion

Retinal vein occlusion can cause blindness, and features neuronal dysfunction, inflammation and breakdown of vascular integrity. Here the authors report a non-apoptotic role of endothelial caspase-9 in regulating blood-retina barrier integrity and neuronal survival, which can be therapeutically targeted in a mouse model of retinal vein occlusion

Author Correction: Endothelial activation of caspase-9 promotes neurovascular injury in retinal vein occlusion

An amendment to this paper has been published and can be accessed via a link at the top of the paper