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Bordetella pertussis is the causative agent of whooping cough in humans, a disease that has recently experienced a resurgence. In contrast, Bordetella bronchiseptica infects the respiratory tract of various mammalian species, causing a range of symptoms from asymptomatic chronic carriage to acute illness. Both pathogens utilize type III secretion system (T3SS) to deliver the effector protein BteA into host cells. Once injected, BteA triggers a cascade of events leading to caspase 1-independent necrosis through a mechanism that remains incompletely understood. We demonstrate that BteA-induced cell death is characterized by the fragmentation of the cellular endoplasmic reticulum and mitochondria, the formation of necrotic balloon-like protrusions, and plasma membrane permeabilization. Importantly, genome-wide CRISPR-Cas9 screen targeting 19,050 genes failed to identify any host factors required for BteA cytotoxicity, suggesting that BteA does not require a single nonessential host factor for its cytotoxicity. We further reveal that BteA triggers a rapid and sustained influx of calcium ions, which is associated with organelle fragmentation and plasma membrane permeabilization. The sustained elevation of cytosolic Ca 2+ levels results in mitochondrial calcium overload, mitochondrial swelling, cristolysis, and loss of mitochondrial membrane potential. Inhibition of calcium channels with 2-APB delays both the Ca 2+ influx and BteA-induced cell death. Our findings indicate that BteA exploits essential host processes and/or redundant pathways to disrupt calcium homeostasis and mitochondrial function, ultimately leading to host cell death.IMPORTANCEThe respiratory pathogens Bordetella pertussis and Bordetella bronchiseptica exhibit cytotoxicity toward a variety of mammalian cells, which depends on the type III secretion effector BteA. Moreover, the increased virulence of B. bronchiseptica is associated with enhanced expression of T3SS and BteA. However, the molecular mechanism underlying BteA cytotoxicity is elusive. In this study, we performed a CRISPR-Cas9 screen, revealing that BteA-induced cell death depends on essential or redundant host processes. Additionally, we demonstrate that BteA disrupts calcium homeostasis, which leads to mitochondrial dysfunction and cell death. These findings contribute to closing the gap in our understanding of the signaling cascades targeted by BteA., Competing Interests: The authors declare no conflict of interest.

Background and Purpose: Orbital lesions are rare but serious. Their characterization remains challenging. Diagnosis is based on biopsy or surgery, which implies functional risks. It is necessary to develop noninvasive diagnostic tools. The goal of this study was to evaluate the diagnostic performance of dynamic contrast-enhanced MR imaging at 3T when distinguishing malignant from benign orbital tumors on a large prospective cohort., Materials and Methods: This institutional review board-approved prospective single-center study enrolled participants presenting with an orbital lesion undergoing a 3T MR imaging before surgery from December 2015 to May 2021. Morphologic, diffusion-weighted, and dynamic contrast-enhanced MR images were assessed by 2 readers blinded to all data. Univariable and multivariable analyses were performed. To assess diagnostic performance, we used the following metrics: area under the curve, sensitivity, and specificity. Histologic analysis, obtained through biopsy or surgery, served as the criterion standard for determining the benign or malignant status of the tumor., Results: One hundred thirty-one subjects (66/131 [50%] women and 65/131 [50%] men; mean age, 52 [SD, 17.1] years; range, 19-88 years) were enrolled. Ninety of 131 (69%) had a benign lesion, and 41/131 (31%) had a malignant lesion. Univariable analysis showed a higher median of transfer constant from blood plasma to the interstitial environment ( K trans ) and of transfer constant from the interstitial environment to the blood plasma (minute -1 ) (Kep) and a higher interquartile range of K trans in malignant-versus-benign lesions (1.1 minute -1 versus 0.65 minute -1 , P  = .03; 2.1 minute -1 versus 1.1 minute -1 , P  = .01; 0.81 minute -1 versus 0.65 minute -1 , P  = .009, respectively). The best-performing multivariable model in distinguishing malignant-versus-benign lesions included parameters from dynamic contrast-enhanced imaging, ADC, and morphology and reached an area under the curve of 0.81 (95% CI, 0.67-0.96), a sensitivity of 0.82 (95% CI, 0.55-1), and a specificity of 0.81 (95% CI, 0.65-0.96)., Conclusions: Dynamic contrast-enhanced MR imaging at 3T appears valuable when characterizing orbital lesions and provides complementary information to morphologic imaging and DWI., (© 2024 by American Journal of Neuroradiology.)

Objectives: To differentiate OCVM from other orbital lesions using structural MRI., Methods: This IRB-approved a historical-prospective cohort single-center analysis of a prospective cohort that included consecutive adult patients presenting with an orbital lesion undergoing a 3T MRI before surgery from December 2015 to May 2021. Two readers blinded to all data read all MRIs assessing structural MRI characteristics. A univariate analysis followed by a stepwise multivariate analysis identified structural MRI features showing the highest sensitivity and specificity when diagnosing OCVM., Results: One hundred ninety-one patients with 30/191 (16%) OCVM and 161/191 (84%) other orbital lesions were included. OCVM were significantly more likely to present with a higher signal intensity than that of the cortex on T2WI: 26/29 (89.7%) versus 28/160 (17.5%), p < 0.001, or with a chemical shift artifact (CSA): 26/29 (89.7%) versus 16/155 (10.3%), p < 0.001, or to present with a single starting point of enhancement, as compared to other orbital lesions: 18/29 (62.1%) versus 4/159 (2.5%), p = 0.001. The step-wise analysis identified 2 signatures increasing performances. Signature 1 combined a higher signal intensity than that of the cortex on T2WI and a CSA. Signature 2 included these two features and the presence of a single starting point of enhancement. Sensitivity, specificity, and accuracy were 0.83, 0.94, and 0.92 for signature 1 and 0.97, 0.93, and 0.93 for signature 2, respectively., Conclusion: Structural MRI yields high sensitivity and specificity when diagnosing OCVM., Key Points: • Structural MRI shows high sensitivity and specificity when diagnosing orbital cavernous venous malformation. • We identified two signatures combining structural MRI features which might be used easily in routine clinical practice. • The combination of higher signal intensity of the lesion as compared to the cortex on T2WI and of a chemical shift artifact yields a sensitivity and specificity of 0.83 and 0.94 for the diagnosis of orbital cavernous venous malformation, respectively., (© 2022. The Author(s), under exclusive licence to European Society of Radiology.)

Purpose: The purpose of this prospective study was to determine the capabilities of intravoxel incoherent motion (IVIM) MRI at 3 Tesla in discriminating between IgG4-related orbital disease (IgG4-ROD) and other causes of orbital inflammation., Materials and Methods: Main selection criteria for the patients enrolled in this prospective study were age over 18 years and histopathologicaly proven orbital inflammatory lesion. MRI examinations were performed prior to surgery and treatment in all patients with suspected orbital inflammation. Two neuroradiologists, blinded to clinical data, independently analyzed structural MRI examinations and IVIM sequences obtained with 15 b values ranging from 0 to 2000 s/mm². Apparent diffusion coefficient (ADC), "true" diffusion coefficient (D), perfusion fraction (f) and pseudodiffusion coefficient (D*) values were calculated from all orbital lesions. Diagnostic capabilities of IVIM parameters were assessed using receiver operating-characteristic (ROC) curves and area under the curve (AUC). Sensitivity, specificity, and accuracy of IVIM parameters were calculated for the best threshold values and reported with their corresponding 95% confidence intervals (CI)., Results: Thirty-five patients (21 women and 14 men; mean age, 49.2 ± 13.75 [SD] years; age range: 23-77 years) with 48 orbital lesions were enrolled in the study. Fifteen patients (15/35; 43%) had IgG4-ROD and 20 (20/35; 57%) had other causes of orbital inflammation. Median D value was significantly greater in patients with IgG4-ROD (1 × 10 -3  mm 2 /s; interquartile range [IQR]: 0.9 × 10 -3 ; 1.2 × 10 -3 ) as compared to patients with non IgG4-ROD (0.80 × 10 -3 mm 2 /s; IQR: 0.7 × 10 -3 ; 1 × 10 -3 ) (P = 0.04). There was no significant difference for ADC, f or D*. Area under the curve were of 0.54, 0.73, 0.63 and 0.56 for ADC, D, f and D*, respectively. Optimal threshold derived from ROC curves for D was 0.87 × 10 -3 mm 2 /s, yielding 92% sensitivity (95% CI: 62-100%) and 71% specificity (95% CI: 44-90%) for the diagnosis of IgG4-ROD. No differences in standard morphological MRI criteria were found between IgG4-ROD and non IgG4-ROD., Conclusion: Our study shows that IVIM MRI is a useful imaging technique to distinguish IgG4-ROD from other causes of orbital inflammation., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interest., (Copyright © 2021 Société française de radiologie. Published by Elsevier Masson SAS. All rights reserved.)