Inflammation is increasingly recognized as an important contributor to a host of CNS disorders; however, its regulation in the brain is not well delineated. Nucleotide-binding domain, leucine-rich repeat, pyrin domain containing 3 (NLRP3) is a key component of the inflammasome complex, which also includes ASC (apoptotic speck-containing protein with a card) and procaspase-1. Inflammasome formation can be triggered by membrane P2X 7 R engagement leading to cleavage-induced maturation of caspase-1 and interleukin-1␤ (IL-1␤)/IL-18. This work shows that expression of the Nlrp3 gene was increased Ͼ100-fold in a cuprizone-induced demyelination and neuroinflammation model. Mice lacking the Nlrp3 gene (Nlrp3 Ϫ/Ϫ ) exhibited delayed neuroinflammation, demyelination, and oligodendrocyte loss in this model. These mice also showed reduced demyelination in the experimental autoimmune encephalomyelitis model of neuroinflammation. This outcome is also observed for casp1 Ϫ/Ϫ and IL-18 Ϫ/Ϫ mice, whereas IL-1␤ Ϫ/Ϫ mice were indistinguishable from wild-type controls, indicating that Nlrp3-mediated function is through caspase-1 and IL-18. Additional analyses revealed that, unlike the IL-1␤ Ϫ/Ϫ mice, which have been previously shown to show delayed remyelination, Nlrp3 Ϫ/Ϫ mice did not exhibit delayed remyelination. Interestingly, IL-18Ϫ/Ϫ mice showed enhanced remyelination, thus providing a possible compensatory mechanism for the lack of a remyelination defect in Nlrp3 Ϫ/Ϫ mice. These results suggest that NLRP3 plays an important role in a model of multiple sclerosis by exacerbating CNS inflammation, and this is partly mediated by caspase-1 and IL-18. Additionally, the therapeutic inhibition of IL-18 might decrease demyelination but enhance remyelination, which has broad implications for demyelinating diseases.

Evaluation of the central nervous system (CNS) in the developing mouse presents unique challenges given the complexity of ontogenesis, marked structural reorganization over very short distances in three dimensions each hour, and numerous developmental events susceptible to genetic and environmental influences. Developmental defects affecting the brain and spinal cord arise frequently both in utero and perinatally as spontaneous events, following teratogen exposure, and as sequelae to induced mutations, and thus are a common factor in embryonic and perinatal lethality in many mouse models. Knowledge of normal organ and cellular architecture and differentiation throughout the mouse’s lifespan is crucial to identify and characterize neurodevelopmental lesions. By providing a well-illustrated overview summarizing major events of normal in utero and perinatal mouse CNS development with examples of common developmental abnormalities, this annotated, color atlas can be used to identify normal structure and histology when phenotyping genetically engineered mice (GEM) and will enhance efforts to describe and interpret brain and spinal cord malformations as causes of mouse embryonic and perinatal lethal phenotypes. The schematics and images in this atlas illustrate major developmental events during gestation from embryonic day (E) 7.5 to E18.5 and after birth from postnatal day (P)1 to P21.

We have shown previously the importance of MHC class II for central nervous system remyelination; however, the function of MHC class II during cuprizone-induced demyelination has not been examined. Here, we show that I-A β −/− mice exhibit significantly reduced inflammation and demyelination. RAG-1 −/− mice are indistinguishable from controls, indicating T cells may not play a role. The role of MHC class II depends on an intact cytoplasmic tail that leads to the production of IL-1β, TNF-α, and nitric oxide, and oligodendrocyte apoptosis. Thus, the function of MHC class II cytoplasmic tail appears to increase microglial proliferation and activation that exacerbates demyelination.

Purpose Determine the roles of the phosphatidylinositol 3-kinase (PI3K) isoforms p110α and p110β in PTEN-deficient, estrogen receptor α (ER)-positive breast cancer, and the therapeutic potential of isoform-selective inhibitors. Experimental Design Anti-estrogen-sensitive and -resistant PTEN-deficient, ER+ human breast cancer cell lines, and mice bearing anti-estrogen-resistant xenografts were treated with the anti-estrogen fulvestrant, the p110α inhibitor BYL719, the p110β inhibitor GSK2636771, or combinations. Temporal response to growth factor receptor-initiated signaling, growth, apoptosis, predictive biomarkers, and tumor volumes were measured. Results p110β primed cells for response to growth factor stimulation. While p110β inhibition suppressed cell and tumor growth, dual targeting of p110α/β enhanced apoptosis and provided sustained tumor response. The growth of anti-estrogen-sensitive cells was inhibited by fulvestrant, but fulvestrant inconsistently provided additional therapeutic effects beyond PI3K inhibition alone. Treatment-induced decreases in phosphorylation of AKT and Rb were predictive of therapeutic response. Short-term drug treatment induced tumor cell apoptosis and proliferative arrest to induce tumor regression, while long-term treatment only suppressed proliferation to provide durable regression. Conclusions p110β is the dominant PI3K isoform in PTEN-deficient, ER+ breast cancer cells. Upon p110β inhibition, p110α did not induce significant reactivation of AKT, but combined targeting of p110α/β most effectively induced apoptosis in vitro and in vivo and provided durable tumor regression. Since apoptosis and tumor regression occurred early but not late in the treatment course, and proliferative arrest was maintained throughout treatment, p110α/β inhibitors may be considered short-term cytotoxic agents and long-term cytostatic agents.

Rodent progressive cardiomyopathy (PCM) encompasses a constellation of microscopic findings commonly seen as a spontaneous background change in rat and mouse hearts. Primary histologic features of PCM include varying degrees of cardiomyocyte degeneration/necrosis, mononuclear cell infiltration, and fibrosis. Mineralization can also occur. Cardiotoxicity may increase the incidence and severity of PCM, and toxicity-related morphologic changes can overlap with those of PCM. Consequently, sensitive and consistent detection and quantification of PCM features are needed to help differentiate spontaneous from test article-related findings. To address this, we developed a computer-assisted image analysis algorithm, facilitated by a fully convolutional network deep learning technique, to detect and quantify the microscopic features of PCM (degeneration/necrosis, fibrosis, mononuclear cell infiltration, mineralization) in rat heart histologic sections. The trained algorithm achieved high values for accuracy, intersection over union, and dice coefficient for each feature. Further, there was a strong positive correlation between the percentage area of the heart predicted to have PCM lesions by the algorithm and the median severity grade assigned by a panel of veterinary toxicologic pathologists following light microscopic evaluation. By providing objective and sensitive quantification of the microscopic features of PCM, deep learning algorithms could assist pathologists in discerning cardiotoxicity-associated changes.