Mouse Model System Research Articles

Peripheral MC1R Activation Modulates Immune Responses and is Neuroprotective in a Mouse Model of Parkinson’s Disease

BackgroundMelanocortin 1 receptor (MC1R) is a key pigmentation gene, and loss-of-function of MC1R variants that produce red hair may be associated with Parkinson’s disease (PD). We previously reported compromised dopaminergic neuron survival in Mc1r mutant mice and dopaminergic neuroprotective effects of local injection of a MC1R agonist to the brain or a systemically administered MC1R agonist with appreciable central nervous system (CNS) permeability. Beyond melanocytes and dopaminergic neurons, MC1R is expressed in other peripheral tissues and cell types, including immune cells. The present study investigates the impact of NDP-MSH, a synthetic melanocortin receptor (MCR) agonist that does not cross BBB, on the immune system and the nigrostriatal dopaminergic system in mouse model of PD.MethodsC57BL/6 mice were treated systemically with MPTP.HCl (20 mg/kg) and LPS (1 mg/kg) from day 1 to day 4 and NDP-MSH (400 µg/kg) or vehicle from day 1 to day 12 following which the mice were sacrificed. Peripheral and CNS immune cells were phenotyped and inflammatory markers were measured. The nigrostriatal dopaminergic system was assessed behaviorally, chemically, immunologically, and pathologically. To understand the role of regulatory T cells (Tregs) in this model, CD25 monoclonal antibody was used to deplete CD25 + Tregs.ResultsSystemic NDP-MSH administration significantly attenuated striatal dopamine depletion and nigral dopaminergic neuron loss induced by MPTP + LPS. It improved the behavioral outcomes in the pole test. Mc1r mutant mice injected with NDP-MSH in the MPTP and LPS paradigm showed no changes in striatal dopamine levels suggesting that the NDP-MSH acts through the MC1R pathway. Although no NDP-MSH was detected in the brain, peripheral, NDP-MSH attenuated neuroinflammation as observed by diminished microglial activation in the nigral region, along with reduced TNF-α and IL1β levels in the ventral midbrain. Depletion of Tregs was associated with diminished neuroprotective effects of NDP-MSH.ConclusionsOur study demonstrates that peripherally acting NDP-MSH confers protection on dopaminergic nigrostriatal neurons and reduces hyperactivated microglia. NDP-MSH modulates peripheral immune responses, and Tregs may be involved in the neuroprotective effect of NDP-MSH.

Study of the effects of trehalose on the enteric and central nervous system in a transgenic mouse model of Parknison's disease

Study of the effects of trehalose on the enteric and central nervous system in a transgenic mouse model of Parknison's disease

Talazoparib enhances the quinacrine-mediated apoptosis in patient-derived oral mucosa CSCs by inhibiting BER pathway through the modulation of GCN5 and P300.

The presence of cancer stem cells (CSCs) in the tumor microenvironment (TME) is majorly responsible for the development and recurrence of cancer. Earlier reports suggested that upon DNA damage, poly-(ADP-ribose) polymerase-1 (PARP-1) helps in chromatin modulation and DNA repair process, thereby promoting CSC survival. But whether a combination of DNA damaging agents along with PARP inhibitors can modulate chromatin assembly, inhibit DNA repair processes, and subsequently target CSCs is not known. Hence, we have investigated the effect of nontoxic bioactive compound quinacrine (QC) and a potent PARP inhibitor Talazoparib in patient-derived oral mucosa CSCs (OM-CSCs) and in vivo xenograft mice preclinical model systems. Data showed that QC + Talazoparib inhibited the PARP-1-mediated chromatin remodelers' recruitment and deregulated HAT activity of GCN5 (general control nonderepressible-5) and P300 at DNA damage site, thereby preventing the access of repair proteins to the damaged DNA. Additionally, this combination treatment inhibited topoisomerase activity, induced topological stress, and induced apoptosis in OM-CSCs. Similar results were observed in an in vivo xenograft mice model system. Collectively, the data suggested that QC + Talazoparib treatment inhibited BER pathway, induced genomic instability and triggered apoptosis in OM-CSCs through the deregulation of PARP-1-mediated chromatin remodelers (GCN5 and P300) activity. Schematic representation of QC + Talazoparib-induced apoptosis in oral mucosa CSCs. (1) Induction of DNA damage takes place after QC treatment (2) PARP1-mediated PARylation at the site of DNA damage, which recruits multiple chromatin remodelers (3) Acetylation at the histone tails relax the structure of chromatin and recruits the BER pathway proteins at the site of DNA damage. (4) BER pathway activated at the site of DNA damage. (5) CSCs survive after successful repair of DNA damage. (6) Treatment of QC-treated CSCs with PARP inhibitor Talazoparib (7) Inhibition of PARylation results in failure of chromatin remodelers to interact with PARP1. (8) Inhibition of acetylation status leads to chromatin compaction. (9) BER pathway proteins are not recruited at the site of DNA damage, resulting in inhibition of BER pathway and accumulation of unrepaired DNA damage, leading to apoptosis and cell death.

P264 Using antisense oligonucleotide therapy to rescue dystrophin (DMD) in the central nervous system in the mdx23 mouse model of Duchenne muscular dystrophy

P264 Using antisense oligonucleotide therapy to rescue dystrophin (DMD) in the central nervous system in the mdx23 mouse model of Duchenne muscular dystrophy

OS10.7.A TUMOR-ASSOCIATED ASTROCYTES PROMOTE TUMOR PROGRESSION OF SONIC HEDGEHOG MEDULLOBLASTOMA BY SECRETING LCN2

Abstract BACKGROUND Sonic Hedgehog (SHH) subgroup of medulloblastoma (MB) accounts for about 25% of all subgroups of MB. Tumor microenvironment (TME) may play a key role in the tumor progression and therapeutic resistance. Tumor-associated astrocytes (TAAs) are reshaped to drive tumor progression through multiple paracrine signals. However, the mechanism by which TAAs modulate MB cells remains elusive. MATERIAL AND METHODS We explored the function of TAAs of SHH-MB in transgenic mouse model and co-culture system by a series of molecular biological techniques. To illuminate the TAAs distribution pattern during tumor progression of MB, we firstly detected MB transgenic mice bearing tumor at different time points by nuclear Magnetic resonance imaging (MRI). Histologic sections were then evaluated under microscope after H&E staining. The RNA-sequencing was also performed to evaluate differential expression between normal astrocytes (ASs) and tumor-associated astrocytes (TAAs). Bio-informatic analysis was followed to find the specific gene expressed in TAAs. Drug treatment of TAA inhibitor was finally applied in the animal model to clarify its effects on tumor progression. RESULTS We illuminated that TAAs showed a specific and dynamic pattern during SHH-MB development. Most TAAs gathered to the tumor margin during the tumor progression, rather than evenly distributed in the early-stage tumors and dissemination foci. We further demonstrated that LCN2 secreted by TAAs could promote the tumor growth and was correlated with the poor prognosis of MB patients. Knocking down LCN2 in TAAs in vitro impeded the proliferation and migration abilities of MB cells. In addition, we identified that TAAs accelerated the tumor growth by secreting LCN2 via STAT3 signaling pathway. Accordingly, blockade of STAT3 signaling by its inhibitor WP1066 in TAAs abrogated the effects of LCN2 on tumor progression in vitro and in vivo. CONCLUSION We for the first time clarified that LCN2, secreted by TAAs, could promote MB tumor progression via STAT3 pathway and has potential prognostic value. Our findings unveiled a new sight in reprogramming the TME of SHH-MB and provided a potential therapeutic strategy targeting TAAs.

Omega-3 with and without insulin replacement alleviates detrimental effects of type II diabetes on reproductive system of male C57BL/6 mice

Aimsthis study aimed to examine the protective role of omega-3 and insulin on reproductive system of the male mouse model of type II diabetes mellitus (T2DM), especially DNA integrity and chromatin quality. Main methodsadult age-matched mice were divided into intact, sham, or T2DM groups (n = 7) which received a high-fat diet/low-dose streptozotocin. T2DM-induced animals underwent no treatment as diabetic control (T2DM), received omega-3 (T2DM + Omg3), received insulin (T2DM + Ins) and their combination (T2DM + Omg3 + Ins) for 35 days. After which, testicular and sperm parameters and testosterone levels were evaluated. Key findingsour findings revealed that the various examined parameters were comparable between the intact and sham groups, while most testicular and sperm parameters were affected by T2DM. Treatment of T2DM-induced animals with omega-3, alone and in combination with insulin, significantly improved sperm motility, normal morphology, sperm chromatin quality, DNA integrity, Leydig cell number and non-significantly testosterone levels. SignificanceT2DM interferes with spermatogenesis and steroidogenesis as well as sperm quality and DNA integrity, which can be partially ameliorated by long-term administration of omega-3 in combination with or without insulin. Although our findings should be confirmed in clinical studies, since previous clinical trials have found omega-3 consumption to be beneficial in humans, its use seems to be safe and effective.

The impact of non-caloric artificial sweetener aspartame on female reproductive system in mice model

BackgroundArtificial sweeteners, used as sugar substitutes have found their ways into almost all the food items due to the notion that they are non-caloric. Aspartame is used in numerous food products throughout the world. The primary users of aspartame include diabetics and calorie conscious people who intend to limit their calorie intake.MethodsFemale Swiss albino mice were divided into three groups (12 mice each) for the duration of 30 and 60 days consecutively. The treatment groups received 40 mg/kg b. w. aspartame orally. Hormone assays using ELISA and tissue histopathology have been performed along with the fertility assay to access the treatment outcomeon the fertility of treated mice in comparison to controls.ResultsPresent study reports that female mice treated with aspartame for 30 and 60 days showed significant reduction in body weight, relative organ weight of (liver and kidney) and gonadosomatic index. These changes were more significantly recorded in 60 days treatment group. Aspartame treated animals for 30 and 60 days showed duration-dependent decrease gonandotropins (follicle stimulating hormone and luteinizing hormone), and steroids (estradiol and progesterone). Moreover, severe histopathological changes, reduction in number of growing follicles, degenerative changes in follicular structure, corona radiata and zonagranulosa were also observed. Besides, histomorphological changes were also observed in the uterine structure including atrophic uterine endometrial glands, contracted endometrial lining, disruption of the endometrial structure and the shapes of blood vessels were also altered.ConclusionNon-nutritive artificial sweeteners including aspartame negatively impact the function of ovaries and feedback mechanism of reproductive hormones by affecting the hypothalamic–pituitary–gonadal axis. In light of present findings the aspartame negatively impacted the reproductive system of female mice. More studies are required to identify the molecular mechanism and the pathways involved.

Oral exposure to inorganic mercury or methylmercury elicits distinct pro-inflammatory and pro-oxidant intestinal responses in a mouse model system.

Humans are mainly exposed to mercury (Hg) through contaminated foodstuffs. However, the effects of Hg on the intestinal tract have received little attention. We performed a subchronic exposure to inorganic mercury or methylmercury in mice through drinking water (1, 5 or 10mg/L for four months) to evaluate their intestinal impact. Histological, biochemical and gene expression analyses showed that both Hg species induced oxidative stress in small intestine and colon, while inflammation was mainly detected in the colon. Increased fecal albumin content indicated a compromised epithelial barrier. Mucus production was possibly also affected, as an increase in Muc2 expression was detected. However, differential effects were detected between both Hg species. Activation of p38 MAPK and increased crypt depth were detected in colon only with MeHg. Minor differences in microbiota composition were detected between unexposed and exposed mice. Although significant differences were detected between both Hg species at 10mg/L, only the relative abundances of low abundance taxa were affected. Concentrations of microbial-derived short-chain fatty acids were decreased, suggesting an effect on microbial metabolism or increased demand by the intestinal epithelium. Results obtained confirm previous in vitro studies and highlights the intestinal mucosa as an initial target of Hg.

Protecting human amnion and chorion matrices during processing: Performance enhancement in a diabetic mouse model and human co-culture system.

Recent evidence suggests that protecting human amnion and chorion matrices (HACM) during processing enhances the performance of HACM for wound repair and tissue regeneration. We utilised a diabetic (db/db) delayed wound healing mouse model. Treatment of db/db full-thickness excisional wounds with HACM, processed with a polyampholyte preservative accentuated the proliferative phase of wound healing that decreased the time necessary to heal wounds. Polyampholyte protection improved the preservation of growth factors and cytokines during room temperature storage following E-beam sterilisation and improved its function in wound healing applications. Our findings indicate protected HACM tissue up-regulated MIP2, NF-kB, TNF-α, KI-67, and Arg1 (0.6-fold to 1.5-fold) but those changes were not statistically significant. Immunofluorescent assessment identifying cell activity illustrated an induction of the proliferative phase of wound healing and a switch from an inflammatory macrophage phenotype (M1) to a pro-regenerative macrophage phenotype (M2a). Genomic profiling of 282 genes was performed using Nanostring from co-cultures of human macrophages and fibroblasts. The polyampholyte + HACM-treated group, compared with the HACM or polyampholyte alone groups, had a statistically significant up-regulation (32-368 fold) of 12 genes primarily involved in macrophage plasticity including CLC7, CD209, CD36, HSD11B1, ICAM1, IL1RN, IL3RA, ITGAX, LSP1, and PLXDC2 (adj. p-value < 0.05). The polyampholyte alone group demonstrated statistically significant down-regulation of four genes ADRA2, COL7A1, CSF3, and PTGS2 (adj. p < 0.05). The HACM alone group up-regulated four genes ATG14, CXCL11, DNMT3A, and THBD, but the results were not statistically significant. Biomechanical measurements indicated that wounds treated with polyampholyte-protected HACM had more tensile integrity compared with wounds treated with HACM alone. These findings indicate that better protection of HACM during processing stabilises the HACM matrix, which may lead to improved wound healing outcomes.

The Effects of the Levels of Hypoxia in the Olfactory Nervous System in Mouse Model.

Intermittent hypoxia (IH) results in low-grade inflammation, sympathetic overactivity, and oxidative stress. However, the specific effects of IH on olfaction have not yet been directly assessed and remain unclear. Therefore, the purpose of this study was to investigate the cytotoxic effects of IH exposure on the mouse olfactory epithelium and the relationship between the concentration of hypoxia and the degree of destruction of the olfactory system. Thirty mice were randomly divided into six groups: control (room air for 4weeks), recovery control (room air for 5weeks), IH 5% oxygen concentration, IH 7% oxygen concentration, recovery 5% hypoxia, and recovery 7% hypoxia groups. Mice in the two hypoxia groups were exposed to 5% and 7% oxygen for 4weeks. Mice in the two recovery groups were exposed to room air for 1week after 4weeks of hypoxia period. Based on, the olfactory marker protein (OMP), Olfr1507, ADCY3, and GNAL were lower, whereas S100b and NGFRAP1 messenger RNA (mRNA) levels were higher in the 5% hypoxia group than those in the control group in the olfactory neuroepithelium. In the brain tissue, the changes in RNA analysis for Olfr 1507, OMP, ADCY, and GNAL mRNA were not typical. However, NeuN and GFAP levels were decreased under 5% hypoxia in the brain tissue. In the recovery state, CNPase, S100b and NeuN levels were increased significantly in both the olfactory neuroepithelium and brain tissue in the 5% hypoxia group. The change in RNA activity in PCR was much higher in the 5% hypoxia group than in the 7% hypoxia group. Our findings suggest that IH damages the olfactory neuroepithelium and brain tissue in mouse model. The activity of olfactory marker genes and neurogenesis in the olfactory neuroepithelium were decreased. The levels of oxygen may be affect changes in the olfactory neuroepithelium. The olfactory ensheathing cell may be a major factor in the recovery of the olfactory neuroepithelium.

MicroRNA-1 targets ribosomal protein genes to regulate the growth, development and reproduction of Schistosoma japonicum

Eggs laid by mature female schistosomes are primarily responsible for the pathogenesis of schistosomiasis and critical for transmission. Consequently, elucidating the mechanism of sexual maturation as well as egg production may lead to new strategies for the control of schistosomiasis. MicroRNAs (miRNAs) are involved in multiple biological processes including reproduction in many organisms, yet their roles have not been well characterized in schistosomes. Here, we investigated microRNA-1 (miR-1), which was downregulated gradually in both male and female Schistosoma japonicum after they reached sexually maturity. The expression of miR-1, as shown with quantitative reverse transcription PCR (qRT-PCR), was lower in the reproductive organs of adult females compared with the somatic tissues. Overexpression of miR-1 in adult worms destroyed the morphological architecture of reproductive organs and reduced the subsequent oviposition, which may be due to the activation of apoptosis pathways. Through in silico analysis, 34 potential target genes of miR-1 were identified, including five ribosomal protein genes, called rp-s13, rp-l7ae, rp-l14, rp-l11 and rp-s24e. In vitro dual-luciferase reporter gene assays and miRNA overexpression experiments further validated that these ribosomal protein genes were directly regulated by miR-1. In contrast to the gene expression of miR-1, qRT-PCR and in situ hybridization experiments demonstrated these ribosomal protein genes were enriched in the sexual organs of adult females. Using RNA interference to silence the ribosomal protein genes in different developmental stages in a mouse model system, we demonstrated that these miR-1 target genes not only participated in the reproductive development of S. japonicum, but also were required for the growth and survival of the parasite in the early developmental stages. Taken together, our data suggested that miR-1 may affect the growth, reproduction and oviposition of S. japonicum by targeting the ribosomal protein genes, which provides insights for exploration of new anti-schistosome strategies.

Novel Strategy to Combat the Procoagulant Phenotype in Heparin-Induced Thrombocytopenia Using 12-LOX Inhibition.

Heparin-induced thrombocytopenia (HIT) is a major concern for all individuals that undergo cardiac bypass surgeries or require prolonged heparin exposure. HIT is a life- and limb-threatening adverse drug reaction with an immune response following the formation of ultra-large immune complexes that drive platelet activation through the receptor FcγRIIA. Thrombotic events remain high following the standard of care treatment with anticoagulants, while increasing risk of bleeding complications. This study sought to investigate a novel approach to treatment of HIT. Recent reports demonstrate increased procoagulant activity in HIT; however, these reports required analysis ex vivo, and relevance in vivo remains unclear. Using human and mouse model systems, we investigated the cooperativity of PARs (protease-activated receptors) and FcγRIIA in HIT. We challenged humanized FcγRIIA transgenic mice with or without endogenous mouse Par4 (denoted as IIA-Par4+/+ or IIA-Par4-/-, respectively) with a well-established model IgG immune complex (anti [α]-CD9). Furthermore, we assessed the procoagulant phenotype and efficacy to treat HIT utilizing inhibitor of 12-LOX (12[S]-lipoxygenase), VLX-1005, previously reported to decrease platelet activation downstream of FcγRIIA and PAR4, using the triple allele HIT mouse model. IIA-Par4+/+ mice given αCD9 were severely thrombocytopenic, with extensive platelet-fibrin deposition in the lung. In contrast, IIA-Par4-/- mice had negligible thrombocytopenia or pulmonary platelet-fibrin thrombi. We observed that pharmacological inhibition of 12-LOX resulted in a significant reduction in both platelet procoagulant phenotype ex vivo, and thrombocytopenia and thrombosis in our humanized mouse model of HIT in vivo. These data demonstrate for the first time the need for dual platelet receptor (PAR and FcγRIIA) stimulation for fibrin formation in HIT in vivo. These results extend our understanding of HIT pathophysiology and provide a scientific rationale for targeting the procoagulant phenotype as a possible therapeutic strategy in HIT.

Mesothelial Cell Recruitment Towards Sites of Post-Surgical Adhesion Formation in the Peritoneal Cavity

Abstract Background Abdominal surgeries are often inevitable and live-saving procedures, however, they can be associated with post-surgical complications, such as the formation of irreversible scar bands called peritoneal adhesions. Adhesions in the peritoneal cavity can lead to serious health burden by causing small bowel obstruction, infertility, and chronic pelvic pain. Unfortunately, no effective treatment for adhesion patients exists today. Mesothelial cells and mesothelial cell-derived mesenchymal myofibroblasts have been identified as key players in the pathogenesis of adhesions, and thus represent a novel target for pharmacological interventions. Aims Our aim is to study the molecular mechanisms of mesothelial cell recruitment towards peritoneal adhesion sites, which could serve as potential drug targets to effectively prevent the formation of adhesions. Methods By exploiting genetic lineage tracing and experimental animal surgery, we have established a surgical-transgenic mouse model system that allows us to study mesothelial cell recruitment during processes of scar-free wound healing and wound healing associated with adhesion formation. To identify candidate molecules predominantly required for the recruitment of mesothelial cells towards adhesion sites, we apply an untargeted transcriptomics-based research strategy (spatial transcriptomics, single cell RNA sequencing). Results Histological characterization of our mouse model showed that over seven days post-surgery increasing numbers of mesothelial or mesothelial cell-derived cells accumulate at adhesion sites whereas their numbers stay constant in wounds healing without scar formation. Along with these findings, we have determined candidate molecules potentially triggering mesothelial cell migration towards sites of adhesion formation and will next test their proposed function in vivo and in vitro. Conclusions Mesothelial cells and mesothelial cell-derived mesenchymal myofibroblasts particularly accumulate at sites of adhesion formation. Therapeutic targeting of the recruitment mechanism of these cells might represent a novel strategy to prevent post-surgical adhesion formation in the peritoneal cavity.

Hardwiring tissue-specific AAV transduction in mice through engineered receptor expression

The development of transgenic mouse models that express genes of interest in specific cell types has transformed our understanding of basic biology and disease. However, generating these models is time- and resource-intensive. Here we describe a model system, SELective Expression and Controlled Transduction In Vivo (SELECTIV), that enables efficient and specific expression of transgenes by coupling adeno-associated virus (AAV) vectors with Cre-inducible overexpression of the multi-serotype AAV receptor, AAVR. We demonstrate that transgenic AAVR overexpression greatly increases the efficiency of transduction of many diverse cell types, including muscle stem cells, which are normally refractory to AAV transduction. Superior specificity is achieved by combining Cre-mediated AAVR overexpression with whole-body knockout of endogenous Aavr, which is demonstrated in heart cardiomyocytes, liver hepatocytes and cholinergic neurons. The enhanced efficacy and exquisite specificity of SELECTIV has broad utility in development of new mouse model systems and expands the use of AAV for gene delivery in vivo.

The parasite intraerythrocytic cycle and human circadian cycle are coupled during malaria infection

During infections with the malaria parasites Plasmodium vivax, patients exhibit rhythmic fevers every 48 h. These fever cycles correspond with the time the parasites take to traverse the intraerythrocytic cycle (IEC). In other Plasmodium species that infect either humans or mice, the IEC is likely guided by a parasite-intrinsic clock [Rijo-Ferreiraet al., Science 368, 746-753 (2020); Smith et al., Science 368, 754-759 (2020)], suggesting that intrinsic clock mechanisms may be a fundamental feature of malaria parasites. Moreover, because Plasmodium cycle times are multiples of 24 h, the IECs may be coordinated with the host circadian clock(s). Such coordination could explain the synchronization of the parasite population in the host and enable alignment of IEC and circadian cycle phases. We utilized an ex vivo culture of whole blood from patients infected with P. vivax to examine the dynamics of the host circadian transcriptome and the parasite IEC transcriptome. Transcriptome dynamics revealed that the phases of the host circadian cycle and the parasite IEC are correlated across multiple patients, showing that the cycles are phase coupled. In mouse model systems, host-parasite cycle coupling appears to provide a selective advantage for the parasite. Thus, understanding how host and parasite cycles are coupled in humans could enable antimalarial therapies that disrupt this coupling.

Fgf8 regulates first pharyngeal arch segmentation through pouch-cleft interactions.

Introduction: The pharyngeal arches are transient developmental structures that, in vertebrates, give rise to tissues of the head and neck. A critical process underlying the specification of distinct arch derivatives is segmentation of the arches along the anterior-posterior axis. Formation of ectodermal-endodermal interfaces is a key mediator of this process, and although it is essential, mechanisms regulating the establishment of these interfaces vary between pouches and between taxa. Methods: Here, we focus on the patterning and morphogenesis of epithelia associated with the first pharyngeal arch, the first pharyngeal pouch (pp1) and the first pharyngeal cleft (pc1), and the role of Fgf8 dosage in these processes in the mouse model system. Results: We find that severe reductions of Fgf8 levels disrupt both pp1 and pc1 development. Notably, out-pocketing of pp1 is largely robust to Fgf8 reductions, however, pp1 extension along the proximal-distal axis fails when Fgf8 is low. Our data indicate that Fgf8 is required for specification of regional identity in both pp1 and pc1, for localized changes in cell polarity, and for elongation and extension of both pp1 and pc1. Discussion: Based on Fgf8-mediated changes in tissue relationships between pp1 and pc1, we hypothesize that extension of pp1 requires physical interaction with pc1. Overall, our data indicate a critical role for the lateral surface ectoderm in segmentation of the first pharyngeal arch that has previously been under-appreciated.

Abstract 242: A Novel Strategy To Combat The Procoagulant Phenotype In Immune Thrombotic Thrombocytopenia Using 12-LOX Inhibition

The risk of stroke or other thrombotic complications following vaccination of SARS-CoV-2 has been extensively reported since widespread vaccination efforts began in early 2021. This disorder, termed vaccine-induced immune thrombotic thrombocytopenia (VITT), has remarkable overlap in clinical manifestations to that of heparin-induced thrombocytopenia (HIT). HIT and VITT are pathologies caused by IgG immune complexes that activate platelets via Fc Receptor for IgG IIA (FcγRIIA), which are collectively categorized as immune thrombotic thrombocytopenia (ITT) disorders. Thrombotic events remain high following the standard of care treatment with concurrent risk of bleeding complications. This study sought to investigate a novel approach to treatment of ITT. Recent reports demonstrate increased procoagulant activity in ITT. However, these reports required ex vivo analysis, and in vivo relevance remains unclear. Using human and mouse model systems, we investigated the cooperativity of protease activated receptors (PARs) and FcγRIIA in ITT. We challenged humanized FcγRIIA transgenic mice with or without endogenous mouse Par4 (denoted as IIA-Par4 +/+ or IIA-Par4 -/- , respectively) with a well-established model IgG immune complex (αCD9). IIA-Par4 +/+ mice given αCD9 were severely thrombocytopenic, with extensive platelet-fibrin deposition in the lung. In contrast, IIA-Par4 -/- mice had negligible thrombocytopenia or pulmonary platelet-fibrin thrombi. These data demonstrate for the first time the need for dual platelet receptor (PAR and FcγRIIA) stimulation for fibrin formation in ITT in vivo . In human platelets, we observed that PAR1, PAR4, and FcγRIIA each contributed to the procoagulant phenotype, via receptor-specific increases in cytosolic Ca 2+ . As inhibition of 12(S)-lipoxygenase has been reported to decrease platelet activation downstream of FcγRIIA and PAR4, we used inhibitor VLX-1005 and observed significant reduction in both platelet procoagulant phenotype ex vivo , and thrombocytopenia and thrombosis in our humanized mouse model of HIT in vivo . These results extend our understanding of ITT pathophysiology and provide a scientific rationale for targeting the procoagulant phenotype as a possible therapeutic strategy in ITT.

Deubiquitinase USP1 influences the dedifferentiation of mouse pancreatic β-cells

Loss of insulin-secreting β-cells in diabetes may be either due to apoptosis or dedifferentiation of β-cell mass. The ubiquitin-proteasome system comprising E3 ligase and deubiquitinases (DUBs) controls several aspects of β-cell functions. In this study, screening for key DUBs identified USP1 to be specifically involved in dedifferentiation process. Inhibition of USP1 either by genetic intervention or small-molecule inhibitor ML323 restored epithelial phenotype of β-cells, but not with inhibition of other DUBs. In absence of dedifferentiation cues, overexpression of USP1 was sufficient to induce dedifferentiation in β-cells; mechanistic insight showed USP1 to mediate its effect via modulating the expression of inhibitor of differentiation (ID) 2. In an invivo streptozotocin (STZ)-induced dedifferentiation mouse model system, administering ML323 alleviated hyperglycemic state. Overall, this study identifies USP1 to be involved in dedifferentiation of β-cells and its inhibition may have a therapeutic application of reducing β-cell loss during diabetes.

Tobacco and mental health- Deciphering the vulnerability to nicotine in patients with schizophrenia as a function of their dopamine neurotransmission genes: a clinical and preclinical study

IntroductionSchizophrenia (SZ) is a severe and frequent mental disorder that has multifactorial origins (genetic but also environmental vulnerability, gene environment interactions). Our team has shown that in France smoking is common among these patients and often begins before the onset of symptoms. This calls into question the hypothesis of self-medication of psychotic symptoms and cognitive disorders by tobacco consumption, and raises the question of specific interactions between nicotine consumption and the genes of the dopaminergic and cholinergic nicotinic systems, in particular with regard to adolescence, period of neurodevelopmental vulnerability.Objectivesto study (i) the interactions between the DA system and exogenous nicotine in a pre-clinical mouse model (transgenic for DAT) (ii) the impact of smoking on the psychotic and clinical phenotype in a national cohort of SZ patients (iii) interactions between tobacco consumption and several genetic polymorphisms of the dopaminergic and nicotinic system in SZ population. Hypothesis: Disruption of the balance between DA and nicotine systems by nicotine consumption in adolescence may be a key neurobiological mechanism for the emergence of SZ disorders.MethodsThe characterization of the model is behavioral (anxiety, memory, social interactions, locomotion, motor coordination) but also biochemical. For the clinical approach, we exploit the clinical / cognitive / genetic data of a national cohort (Fondamental foundation) and another smaller and local cohort.ResultsWe demonstrate, for the clinical study, that some clinical and cognitive characteristics are associated with tobacco use in schizophrenia patients, with more cognitive distubrances in smokers, against the self medication hypothesis. Genes envionment interactions also demonstrate associations with genes involved in dopaminergic system. Regarding the preclinical study, we show a gene environment interaction, as heterozygote mice for the DAT gene exposed to Nicotine durig a critical neurodevelopmental window ( adolescence) show a loss of familiarity in the social memory test and a loss of cognitive flexibility at the set shifting test, similar to what is found in schizophrenia.ConclusionsTBetter characterization of patients with schizophrenia is necessary to better understand the physiopathology of this disease and explore new personalized preventive and therapeutical targets. We show that tobacco is associated with cognitive disturbances in schizophrenia patients, against selfmedication hypothesis; and in our animal model, that nicotine exposition during the adolescence combined to a moderate cortical and limbic hyperdopaminergia, is associated with persistent cognitive and social deficits, in favor of a gene environment interaction.Disclosure of InterestNone Declared

The RUNX/CBFβ Complex in Breast Cancer: A Conundrum of Context.

Dissecting and identifying the major actors and pathways in the genesis, progression and aggressive advancement of breast cancer is challenging, in part because neoplasms arising in this tissue represent distinct diseases and in part because the tumors themselves evolve. This review attempts to illustrate the complexity of this mutational landscape as it pertains to the RUNX genes and their transcription co-factor CBFβ. Large-scale genomic studies that characterize genetic alterations across a disease subtype are a useful starting point and as such have identified recurring alterations in CBFB and in the RUNX genes (particularly RUNX1). Intriguingly, the functional output of these mutations is often context dependent with regards to the estrogen receptor (ER) status of the breast cancer. Therefore, such studies need to be integrated with an in-depth understanding of both the normal and corrupted function in mammary cells to begin to tease out how loss or gain of function can alter the cell phenotype and contribute to disease progression. We review how alterations to RUNX/CBFβ function contextually ascribe to breast cancer subtypes and discuss how the in vitro analyses and mouse model systems have contributed to our current understanding of these proteins in the pathogenesis of this complex set of diseases.