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Hereditary tyrosinemia type 1 is an autosomal recessive disorder caused by mutations (pathogenic variants) in fumarylacetoacetate hydrolase, an enzyme involved in tyrosine degradation. Its loss results in the accumulation of toxic metabolites that mainly affect the liver and kidneys and can lead to severe liver disease and liver cancer. Tyrosinemia type 1 has a global prevalence of approximately 1 in 100,000 births but can reach up to 1 in 1,500 births in some regions of Québec, Canada. Mutating functionally related "modifier' genes (i.e. genes that, when mutated, affect the phenotypic impacts of mutations in other genes) is an emerging strategy for treating human genetic diseases. In vivo somatic genome editing in animal models of these diseases is a powerful means to identify modifier genes and fuel treatment development. In this study, we demonstrate that mutating additional enzymes in the tyrosine catabolic pathway through liver-specific genome editing can relieve or worsen the phenotypic severity of a murine model of tyrosinemia type 1. Neonatal gene delivery using recombinant adeno-associated viral vectors expressing Staphylococcus aureus Cas9 under the control of a liver-specific promoter led to efficient gene disruption and metabolic rewiring of the pathway, with systemic effects that were distinct from the phenotypes observed in whole-body knockout models. Our work illustrates the value of using in vivo genome editing in model organisms to study the direct effects of combining pathological mutations with modifier gene mutations in isogenic settings., Competing Interests: Conflicts of interest The authors declare that they have no competing interests., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Genetics Society of America.)

Introduction: Pregnancy complications, including preeclampsia (PE), preterm birth (PTB), and intra-uterine growth restriction (IUGR) have individually been associated with inflammation but the combined comparative analysis of their placental profiles at the transcriptomic and histological levels is lacking., Methods: Bulk RNA-sequencing of human placental biopsies from uncomplicated term pregnancies (CTL) and pregnancies complicated with early-onset (EO), and late-onset (LO) PE, as well as PTB and term IUGR were used to characterize individual molecular profiles. We also applied immune-cell-specific cellular deconvolution to address local immune cell compositions and analyzed placental lesions by histology to further characterize these complications., Results: Transcriptome analysis revealed that clinically distinct complications differentiated themselves in unique ways compared to CTLs. Only TMEM136 was commonly modulated. Compared to CTLs, we found that PTB and IUGR were the most distinct, with LOPE being the least distinct. PTB and IUGR revealed differently enhanced inflammatory pathways, where PTB had general inflammatory responses and IUGR had immune cell activation. This inflammation was reflected in the histological profile for PTB only, whereas structural lesions were elevated in all complications. Placental lesions additionally had corresponding enhancement in inflammatory and structural biological processes. We observed that having co-complications, particularly for PTB with or without IUGR, impacted placental transcriptomes. Lastly, cellular deconvolution uncovered shared immune features among the complications., Discussion: Overall, we provide evidence that these pregnancy complications are not only distinct in their clinical manifestations but also in their placental profiles, which could be leveraged to understand their underlying mechanisms and could offer therapeutic targets., Competing Interests: Declaration of competing interest The authors report no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: Postpartum preeclampsia (PPPE) is an under-diagnosed condition, developing within 48 hours to 6 weeks following an uncomplicated pregnancy. The etiology of PPPE is still unknown, leaving patients vulnerable and making the identification and treatment of patients requiring postpartum care an unmet need. We aimed to understand the immune contribution to PPPE at the time of diagnosis, as well as uncover the predictive potential of perinatal biomarkers for the early postnatal identification of high-risk patients., Methods: Placentas were collected at delivery from uncomplicated pregnancies (CTL) and PPPE patients for immunohistochemistry analysis. In this initial study, blood samples in PPPE patients were collected at the time of PPPE diagnosis (48h-25 days postpartum; mean 7.4 days) and compared to CTL blood samples taken 24h after delivery. Single-cell transcriptomics, flow cytometry, intracellular cytokine staining, and the circulating levels of inflammatory mediators were evaluated in the blood., Results: Placental CD163+ cells and 1 st trimester blood pressures can be valuable non-invasive and predictive biomarkers of PPPE with strong clinical application prospects. Furthermore, changes in immune cell populations, as well as cytokine production by CD14+, CD4+, and CD8+ cells, suggested a dampened response with an exhausted phenotype including decreased IL1β, IL12, and IFNγ as well as elevated IL10., Discussion: Understanding maternal immune changes at the time of diagnosis and prenatally within the placenta in our sizable cohort will serve as groundwork for pre-clinical and clinical research, as well as guiding clinical practice for example in the development of immune-targeted therapies, and early postnatal identification of patients who would benefit from more thorough follow-ups and risk education in the weeks following an uncomplicated pregnancy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Couture, Brien, Rechtzigel, Ling, Ledezma-Soto, Duran Bishop, Boufaied, Dal Soglio, Rey, McGraw, Graham and Girard.)

Introduction: The use of antiretroviral therapy drastically reduces vertical transmission of Human Immunodeficiency Virus. However, recent studies demonstrate associations between ART use during pregnancy and placental inflammation, particularly within protease inhibitor (PI)-based regimens. We sought to characterize placental macrophages, namely Hofbauer cells, according to the class of ART used during pregnancy., Methods: Using immunofluorescence and immunohistochemistry, placentas from 79 pregnant people living with HIV (PPLWH) and 29 HIV-uninfected people were analyzed to quantify the numbers and frequencies of leukocytes (CD45 + ) and Hofbauer cells (CD68 + and/or CD163 + ). PPLWH were stratified into three groups based on class of ART: non-nucleoside reverse transcriptase inhibitor (NNRTI)-based, integrase strand-transfer inhibitor (INSTI)-based, and PI-based regimens., Results: Placentas of PPLWH contained significantly more leukocytes and Hofbauer cells than controls. Multivariable analyses revealed that this increase in immune cells was associated with a predominantly CD163 + profile in all ART subgroups compared to the HIV-negative group. This was characterized by an increase in total CD163 + cells in the PI and INSTI subgroups, and a higher frequency of CD163 + cells and CD163 + /CD68 + ratio in the NNRTI and PI subgroups., Discussion: Placentas of PPLWH treated with any ART regimen during their entire pregnancy displayed a selection for CD163 + cells compared to the HIV-negative group, regardless of class of ART, suggesting that class of ART does not intrinsically affect selection of CD163+ and CD68 + Hofbauer cells. Further investigations into the role of Hofbauer cells in ART-associated placental inflammation are warranted to identify the mechanisms behind their potential involvement in maternal-fetal tolerance maintenance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objectives: The incidence of very-early-onset inflammatory bowel disease (VEO-IBD) and early-onset IBD (EO-IBD) is increasing. Here, we report their phenotype and outcomes in a Montreal pediatric cohort., Methods: We analyzed data from patients diagnosed with IBD between January 2014 and December 2018 from the CHU Sainte-Justine. The primary endpoint was to compare the phenotypes of VEO-IBD and EO-IBD. The secondary endpoints involved comparing outcomes and rates of steroid-free clinical remission (SFCR) at 12 (±2) months (m) post-diagnosis and at last follow-up., Results: 28 (14 males) and 67 (34 males) patients were diagnosed with VEO-IBD and EO-IBD, respectively. Crohn's disease (CD) was more prevalent in EO-IBD (64.2% vs. 39.3%), whereas unclassified colitis (IBD-U) was diagnosed in 28.6% of VEO-IBD vs. 10.4% of EO-IBD ( p  < 0.03). Ulcerative colitis (UC) and IBD-U predominantly presented as pancolitis in both groups (VEO-IBD: 76.5% vs. EO-IBD: 70.8%). Combining all disease subtypes, histological upper GI lesions were found in 57.2% of VEO-IBD vs. 83.6% of EO-IBD ( p  < 0.009). In each subtype, no differential histological signature (activity, eosinophils, apoptotic bodies, granulomas) was observed between both groups. At 12 m post-diagnosis, 60.8% of VEO-IBD and 62.7% of EO-IBD patients were in SFCR. At a median follow-up of 56 m, SFCR was observed in 85.7% of VEO-IBD vs. 85.0% of EO-IBD patients., Conclusion: The rate of patients in SFCR at 1-year post-diagnosis and at the end of follow-up did not significantly differ between both groups., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Chapuy, Leduc, Godin, Damphousse, Patey, Dal Soglio, Jantchou and Deslandres.)

Objective: To assess the impact of a quality-improvement initiative designed to increase diagnostic accuracy and adequate management of clinical chorioamnionitis (CC) at a tertiary center. Chorioamnionitis occurs in 1%-13% of term pregnancies and increases maternal and neonatal peripartum complications; often over-diagnosed, it leads to unnecessary investigations and treatments., Methods: This was an interrupted time-series study. In September 2017 two interventions were implemented: (1) staff training and (2) standardized clinical protocol for the management of fever in labor. All singleton term pregnancies were included. CC cases were reviewed in the pre-intervention (2015-2016, n = 179) and post-intervention (2017-2018, n = 142) groups. CC criteria based on the American College of Obstetricians and Gynecologists guidelines, antibiotics, maternal and neonatal outcomes, and pathology were compared. A cost-consequence analysis was performed., Results: Incidence of CC decreased from 8.2 to 5.6 per 10 person-year (P < 0.001). This was associated with a significant increase in diagnostic accuracy from 15.7% to 73.2% (P < 0.001). Weight-adjusted tobramycin dosage improved from 8.8% to 69.1% (P < 0.001). Maternal length of hospitalization and readmissions decreased significantly, without affecting neonatal sepsis rate. Interventions decreased yearly hospital costs associated with CC by 23.4%., Conclusion: Standardizing the management of fever in labor significantly increased the diagnostic accuracy of CC and decreased the misuse of antibiotics in term pregnancies. CC costs decreased by 23.4%., (© 2022 The Authors. International Journal of Gynecology & Obstetrics published by John Wiley & Sons Ltd on behalf of International Federation of Gynecology and Obstetrics.)

Puberty is associated with transient insulin resistance that normally recedes at the end of puberty; however, in overweight children, insulin resistance persists, leading to an increased risk of type 2 diabetes. The mechanisms whereby pancreatic β cells adapt to pubertal insulin resistance, and how they are affected by the metabolic status, have not been investigated. Here, we show that puberty is associated with a transient increase in β cell proliferation in rats and humans of both sexes. In rats, β cell proliferation correlated with a rise in growth hormone (GH) levels. Serum from pubertal rats and humans promoted β cell proliferation, suggesting the implication of a circulating factor. In pubertal rat islets, expression of genes of the GH/serotonin (5-hydroxytryptamine [5-HT]) pathway underwent changes consistent with a proliferative effect. Inhibition of the pro-proliferative 5-HT receptor isoform HTR2B blocked the increase in β cell proliferation in pubertal islets ex vivo and in vivo. Peripubertal metabolic stress blunted β cell proliferation during puberty and led to altered glucose homeostasis later in life. This study identifies a role of GH/GH receptor/5-HT/HTR2B signaling in the control of β cell mass expansion during puberty and identifies a mechanistic link between pubertal obesity and the risk of developing type 2 diabetes.

Competing Interests: Competing interests: WDF reports grants from Canadian Institutes of Health Research, during the conduct of the study; grants from Astra Zeneca, outside the submitted work.

Introduction : The detailed expression pattern of calretinin immunohistochemistry in the transition zone (TZ) of Hirschsprung disease (HSCR) has not yet been reported. This study aims to examine the value of calretinin immunohistochemistry for more accurately determining the distal and proximal border of the TZ in short segment HSCR. Methods : Specimens of pull-through surgery from 51 patients with short form of HSCR were analyzed on two longitudinal strips using hematoxylin and eosin (H&E) staining and calretinin immunohistochemistry. Results : In all but two patients, the first appearance of calretinin expression was seen on mucosal nerve fibers before the appearance of any ganglion cells, indicating the distal border of the TZ. The maximum distance between the distal border of the TZ and the proximal border of the TZ, defined by ganglion cells in a normal density on H&E stained sections, a strong calretinin expression on mucosal nerve fibers and in >80% of submucosal and myenteric ganglion cells, with no nerve hypertrophy and absence of ganglionitis was 60 mm. Conclusion : The distal border of the TZ is characterized by calretinin positive intramucosal neurites in nearly all of short form of HSCR and not by calretinin expression on ganglion cells.

Introduction: There is currently little knowledge on factors associated with the relapse of Crohn's disease (CD) in children. The aims of this study were to describe the risk factors associated with relapse in pediatric CD and the changes in the relapse rate over the past decade., Methods: Patients younger than 18 years and diagnosed between 2009 and 2019 were included in this retrospective cohort study. Clinical, endoscopic, histological, and laboratory data, as well as induction and maintenance treatments, were collected from the medical records. Survival analyses and Cox regression models were used to assess the impact of these risk factors on relapse., Results: Six hundred thirty-nine patients were included. There was a decrease in the clinical relapse rate over the past decade: 70.9% of the patients diagnosed between 2009 and 2014 relapsed as compared with 49.1% of the patients diagnosed between 2015 and 2019 (P < 0.0001). The following variables were associated with clinical relapse: female sex (adjusted hazard ratio [aHR] = 1.52, P = 0.0007), exposure to oral 5-ASA (aHR = 1.44, P = 0.04), use of immunomodulatory agents compared with tumor necrosis factor-alpha inhibitors (methotrexate aHR = 1.73, P = 0.003; thiopurines aHR = 1.63, P = 0.002), presence of granulomas (aHR = 1.34, P = 0.02) and increased eosinophils on intestinal biopsies (aHR = 1.36, P = 0.02), high levels of C-reactive protein (aHR = 1.01, P < 0.0001) and fecal calprotectin (aHR = 1.08, P < 0.0001), and low serum infliximab levels (aHR = 2.32, P = 0.001)., Discussion: Relapse of pediatric CD has decreased in the past decade. The risk of relapse is significantly associated with clinical, endoscopic, histological, and laboratory variables and treatment strategies., (Copyright © 2022 by The American College of Gastroenterology.)

Background and Aims: The aims of this study were to describe the trends in the behavior of pediatric CD during the last decade and to describe the seasonal variation of disease presentation., Methods: Patients under 18 years old and diagnosed between 2009 and 2019 were included. The clinical, endoscopic, histological, and laboratory data were collected from the medical records. We analyzed the trends of these parameters according to the year and season of diagnosis., Results: 654 patients were included in the study. The number of incident CD cases increased yearly. Patients diagnosed between 2015 and 2019 were younger at diagnosis (OR 2.53, p = 0.02), had more perianal diseases (OR: 2.30, p < 0.0001) and more granulomas (OR: 1.61, p = 0.003), but fewer eosinophils (OR: 0.35, p < 0.0001) and less chronic lymphoplasmacytic infiltrate (OR: 0.56, p = 0.008) as compared to the 2009-2014 cohort. There was fewer CD diagnosis during winter. Patients diagnosed in the fall had lower PCDAIs, less failure to thrive and less extensive digestive involvement. Colonic disease was significantly more frequent during summer and fall., Conclusion: The clinical and histological phenotype of CD has changed over time and there are important seasonal trends in the frequency and severity on disease behavior suggesting possible disease triggers., Competing Interests: Declaration of Competing Interest None declared., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Modeling the tumor-immune cell interactions in humanized mice is complex and limits drug development. Here, we generated easily accessible tumor models by transforming either primary skin fibroblasts or induced pluripotent stem cell-derived cell lines injected in immune-deficient mice reconstituted with human autologous immune cells. Our results showed that fibroblastic, hepatic, or neural tumors were all efficiently infiltrated and partially or totally rejected by autologous immune cells in humanized mice. Characterization of tumor-immune infiltrates revealed high expression levels of the dysfunction markers Tim3 and PD-1 in T cells and an enrichment in regulatory T cells, suggesting rapid establishment of immunomodulatory phenotypes. Inhibition of PD-1 by Nivolumab in humanized mice resulted in increased immune cell infiltration and a slight decrease in tumor growth. We expect that these versatile and accessible cancer models will facilitate preclinical studies and the evaluation of autologous cancer immunotherapies across a range of different tumor cell types., Competing Interests: The authors have no conflicts of interest to disclose. C.R. and M.P. are co-founders, shareholders, and officers of the regenerative medicine company Morphocell Technologies, Inc., (© 2021 The Authors.)