This issue features a collection of Physician-Scientist Development articles that highlight the work, challenges, and goals faced along the physician-scientist career path. It is introduced by an Editorial from Oliver Eickelberg, Christopher S. Williams, and Kyu Y. Rhee. The cover image is a collage of drawings that were produced by children who were prompted to illustrate what comes to mind when they think of a physician-scientist. Illustrations were provided by Demetri Kitsios, Liam Snyder, Elizabeth Neal, and Jocelyn L. (clockwise from the top right).
Oxidative stress driven by malfunctioning respiratory complex I (RC-I) is a crucial pathogenic factor in liver ischemia/reperfusion (I/R) injury. This study investigates the role of alkaline ceramidase 3 (ACER3) and its unsaturated long-chain ceramide (CER) substrates in regulating liver I/R injury through RC-I. Our findings demonstrated that I/R upregulated ACER3/Acer3 and decreased unsaturated long-chain CER levels in human and mouse livers. Both global and hepatocyte-specific Acer3 ablation, as well as treatment with CER(d18:1/18:1), led to a significant increase of CER(d18:1/18:1) levels in the liver, which mitigated the I/R-induced hepatocyte damage and inflammation in mice. Mechanistically, Acer3 modulated CER(d18:1/18:1) levels in mitochondria-associated membranes and endoplasmic reticulum (ER), thereby influencing the transport of CER(d18:1/18:1) from ER to mitochondria. Acer3 ablation and CER(d18:1/18:1) treatment elevated CER(d18:1/18:1) in mitochondria, where CER(d18:1/18:1) bound to the RC-I subunit Ndufa6 to inactivate RC-I and reduced reactive oxygen species production in the I/R-injured mouse liver. These findings underscore the role of CER(d18:1/18:1)-Ndufa6 interaction in suppressing RC-I-mediated oxidative-stress-driven pathogenesis in liver I/R Injury.
Kai Wang, Leyi Liao, Hanbiao Liang, Pengxiang Huang, Qingping Li, Baoxiong Zhuang, Chen Xie, Xiangyue Mo, Xuesong Deng, Jieyuan Li, Yang Lei, Minghui Zeng, Cungui Mao, Ruijuan Xu, Cuiting Liu, Xianqiu Wu, Jie Zhou, Biao Wang, Yiyi Li, Chuanjiang Li
We developed a 29-color spectral cytometry panel to enhance nonhuman primate (NHP) models for cross-reactive immunophenotyping. This panel is suitable for biosafety level 4 (BSL-4) viruses and can be used with both human and NHP samples in BSL-2 research settings. Tissues from humans, rhesus monkeys (RhMs), crab-eating macaques (CEMs), and green monkeys (GMs) were stained with a 29-color immunophenotyping panel requiring only two clone substitutions. Comparable staining was observed for all samples. Unbiased analysis showed acceptable overlap in T-cell phenotypes across samples, with differences in human and NHP B cells and granulocytes. In CEMs, most circulating CD8+ T cells were from effector memory cells, with significantly higher levels than in humans (p<0.0001), RhMs (p<0.05), and GMs (p<0.01). Analysis of samples from various anatomical sites revealed distinct location-specific phenotypes. In Nipah-virus-exposed animals, splenocytes showed a substantial increase in IgM+ B cells (p<0.0001) and a reduction in effector memory CD8+ T cells (p<0.0001) compared to unexposed controls. Lymph nodes from Ebola-virus-exposed animals showed a loss of CXCR3+CD8+ T cells vs unexposed controls. This panel may guide the development of additional multi-color panels in preclinical and clinical settings and potentially increase understanding of the pathogenesis of diseases caused by emerging and re-emerging viruses.
Andrew P. Platt, Bobbi Barr, Anthony Marketon, Rebecca Bernbaum, Deja F.P. Rivera, Vincent J. Munster, Daniel S. Chertow, Michael R. Holbrook, Scott M. Anthony, Bapi Pahar
Biliary atresia (BA) is a pediatric liver disease that often necessitates parenteral nutrition (PN) to support growth due to impaired liver function. While soy oil lipid emulsions (SLE) are commonly used in PN, they may contribute to cholestatic liver injury. In contrast, mixed oil lipid emulsions (MLE) show promise in preventing cholestasis in non-BA infants, potentially by restoring bile flow. However, their effectiveness in cases of complete bile duct obstruction, as seen in BA, remains uncertain. To explore the potential benefits of MLE in BA, we utilized a neonatal pig model of bile duct ligation (BDL). Pigs underwent either BDL or sham surgery and were subsequently fed either MLE or SLE via PN, or enterally with formula. The MLE-BDL pigs exhibited significantly greater weight gain compared to those fed SLE or formula enterally. Additionally, MLE-BDL pigs showed higher serum bile acid and gamma-glutamyl transferase concentrations compared to SLE-BDL pigs. However, no significant differences in liver injury, assessed by ductular reaction or fibrosis, were observed between MLE- and SLE-BDL pigs. Based on weight gain alone, MLE may be a superior lipid emulsion for use in neonates with obstructive cholestasis.
Greg Guthrie, Caitlin Vonderohe, Valeria Meléndez Hebib, Barbara Stoll, Douglas Burrin
The role of gamma-delta T (γδT) cells in immune responses to common allergens is poorly understood. Here, we utilized single-cell (sc) transcriptomic analysis of allergen-reactive γδT cells in humans to characterize the transcriptional landscapes and TCR repertoires in response to cockroach (CR) and mouse (MO) allergens. Using a novel Activation-Induced Marker (AIM) assay that allows detection of γδT cells combined with scRNA sequencing and TCR repertoire analysis, we identified both shared and allergen-specific γδT cell activation patterns and gene expression profiles. While CR extract activated both Vδ1 and Vδ2 subsets, MO extract primarily stimulated Vδ2 cells. Our analysis revealed allergen-specific clusters with distinct functional signatures, including enhanced inflammatory responses and cytotoxic effector functions in MO-specific γδT cells and natural killer cell-mediated immunity and IFNγ signaling in CR-specific populations. Comparison of allergic and non-allergic individuals highlighted differences in gene expression and TCR repertoires, including a higher IFNG expression in the CR-allergic compared to non-allergic cohorts, suggesting that phenotypic and functional differences are associated with γδT allergen responses. This study provides insights into the cellular and molecular heterogeneity and functionality of allergen-reactive γδT cells, offering a foundation for understanding their role in allergic diseases and potential therapeutic interventions
Kendall Kearns, Sloan A. Lewis, Esther Dawen Yu, Adam Abawi, Eric Wang, Synaida Maiche, Monalisa Mondal, Pandurangan Vijayanand, Grégory Seumois, Bjoern Peters, Alessandro Sette, Ricardo Da Silva Antunes
Fibroblasts are central to pathogenesis of systemic sclerosis (SSc). However, studies of conventional explant fibroblast cultures incompletely reflect disease biology and treatment response. We isolated a second non-migratory “resident” population of fibroblasts from skin biopsies after outgrowth of explant “migratory” cells. These non-motile resident fibroblasts were compared with migratory cells from the same biopsy, using functional studies, bulk and scRNAseq, and localised in situ by multichannel immunofluorescence. Migratory and resident fibroblast populations in SSc showed distinct pro-fibrotic characteristics and gene expression for pathogenic pathways differing by stage and autoantibody subgroup. TGFβ signalling was highly active in migratory fibroblasts in early stage dcSSc. Conversely, resident fibroblasts had less upregulated TGFβ signalling, especially in late dcSSc. Increased chemokine expression was a hallmark of resident fibroblasts at all stages. In vitro studies confirmed differential response to TGFβ1 and CCL2 between migratory and resident cells. We suggest that migratory fibroblasts are especially important in early skin disease whereas non-migratory fibroblasts may have a regulatory role and contribute more to fibrosis in later stage disease. Thus, we have identified a pathogenic fibroblast population in SSc, not isolated by conventional explant culture, that could play an important role in fibrosis and be targeted therapeutically.
Kristina E.N. Clark, Shiwen Xu, Moustafa Attar, Voon H. Ong, Christopher D. Buckley, Christopher P. Denton
In this episode, Davide Croci, Sandra van Wilpe, and Niven Mehra explain that their manuscript predicts clinical benefit to immunotherapy by analyzing combined biomarkers from circulating tumor DNA and immune cell gene expression data in blood...