Tissue-based T cells are important effectors in the prevention and control of mucosal viral infections – less is known about tissue-based B cells. We demonstrate that B cells and antibody-secreting cells (ASCs) are present in inflammatory infiltrates in skin biopsies of persons during symptomatic HSV2 reactivation and early healing. Both CD20+ B cells, most of which are antigen-inexperienced by co-expression of IgD, and ASCs, characterized by dense IgG RNA expression in combination with CD138, IRF4 and Blimp1 RNA, are seen in association with T cells. ASCs are found clustered with CD4+ T cells, suggesting potential for crosstalk. HSV2-specific antibodies to virus surface antigens are also present in tissue and increase in concentration during HSV2 reactivation and healing, unlike in serum where concentrations remain static over time. B cells, ASCs, and HSV-specific antibody were rarely detected in biopsies of unaffected skin. Evaluation of serial biopsies demonstrate that B cells and ASCs follow a more migratory than resident pattern of infiltration in HSV-affected genital skin, in contrast to T cells. Together, these observations suggest distinct phenotypes of B cells in HSV-affected tissue; dissecting their role in reactivation may reveal new therapeutic avenues to control these infections.
Emily S. Ford, Anton M. Sholukh, RuthMabel Boytz, Savanna S. Carmack, Alexis Klock, Khamsone Phasouk, Danica Shao, Raabya Rossenkhan, Paul T. Edlefsen, Tao Peng, Christine Johnston, Anna Wald, Jia Zhu, Lawrence Corey
As part of the centennial celebration of insulin’s discovery, this review summarizes the current understanding of the genetics, pathogenesis, treatment, and outcomes in type 1 diabetes (T1D). T1D results from an autoimmune response that leads to destruction of the β cells in the pancreatic islet and requires life-long insulin therapy. While much has been learned about T1D, it is now clear that there is considerable heterogeneity in T1D with regards to genetics, pathology, response to immune-based therapies, clinical course, and susceptibility to diabetes-related complications. This review highlights knowledge gaps and opportunities to improve the understanding of T1D pathogenesis and outlines emerging therapies to treat or prevent T1D and reduce the burden of T1D.
Alvin C. Powers
GDP-mannose-pyrophosphorylase-B (GMPPB) facilitates the generation of GDP-mannose, a sugar donor required for glycosylation. GMPPB defects cause muscle disease due to hypoglycosylation of α-dystroglycan (α-DG). Alpha-DG is part of a protein complex, which links the extracellular matrix with the cytoskeleton thus stabilizing myofibers. Mutations of the catalytically inactive homolog GMPPA cause AAMR syndrome, which is characterized by achalasia, alacrima, mental retardation, and muscle weakness. Here we show that Gmppa KO mice recapitulate cognitive and motor deficits. As structural correlates we found cortical layering defects, progressive neuron loss, and myopathic alterations. Increased GDP-mannose levels in skeletal muscle and in vitro assays identify GMPPA as an allosteric feedback inhibitor of GMPPB. Thus, its disruption enhances mannose incorporation into glycoproteins including α-Dg in mice and men. This increases α-Dg turnover and thereby lowers α-Dg abundance. In mice dietary mannose restriction beginning after weaning corrects α-DG hyperglycosylation and abundance, normalizes skeletal muscle morphology, and prevents neuron degeneration and the development of motor deficits. Cortical layering and cognitive performance, however, are not improved. We thus identify GMPPA defects as the first congenital disorder of glycosylation characterized by α-DG hyperglycosylation, unravel underlying disease mechanisms and point to potential dietary treatment options.
Patricia Franzka, Henriette Henze, M. Juliane Jung, Svenja C. Schüler, Sonnhild Mittag, Karina Biskup, Lutz Liebmann, Takfarinas Kentache, José Morales, Braulio Martínez, Istvan Katona, Tanja Herrmann, Antje-Kathrin Huebner, J. Christopher Hennings, Susann Groth, Lennart J. Gresing, Rüdiger Horstkorte, Thorsten Marquardt, Joachim Weis, Christoph Kaether, Osvaldo M. Mutchinick, Alessandro Ori, Otmar Huber, Véronique Blanchard, Julia von Maltzahn, Christian A. Hübner
Troponin C (TnC) is a critical regulator of skeletal muscle contraction: it binds Ca2+ to activate muscle contraction. Surprisingly, the gene encoding fast skeletal TnC (TNNC2) has not yet been implicated in muscle disease. Here, we report two families with pathogenic variants in TNNC2. Patients present with a distinct, dominantly inherited congenital muscle disease. Molecular dynamics simulations suggest that the pathomechanisms by which the variants cause muscle disease include disruption of the binding sites for Ca2+ and for troponin I. In line with these findings, physiological studies in myofibers isolated from patients’ biopsies revealed a markedly reduced force response of the sarcomeres to [Ca2+]. This pathomechanism was further confirmed in experiments in which contractile dysfunction was evoked by replacing TnC in myofibers from healthy control subjects with recombinant, mutant TnC. Conversely, the contractile dysfunction of myofibers from patients was repaired by replacing endogenous, mutant TnC with recombinant, healthy TnC. Finally, we tested the therapeutic potential of the fast skeletal muscle troponin activator tirasemtiv in patients’ myofibers and showed that the contractile dysfunction was repaired. Thus, our data reveal that pathogenic variants in TNNC2 cause congenital muscle disease, and they provide therapeutic angles to repair muscle contractility.
Martijn van de Locht, Sandra Donkervoort, Josine M. de Winter, Stefan Conijn, Leon Begthel, Benno Kusters, Payam Mohassel, Ying Hu, Livija Medne, Colin Quinn, Steven A. Moore, A. Reghan Foley, Gwimoon Seo, Darren T. Hwee, Fady I. Malik, Thomas Irving, Weikang Ma, Henk Granzier, Erik-Jan Kamsteeg, Kalyan Immadisetty, Peter Kekenes-Huskey, Jose Renato Pinto, Nicol Voermans, Carsten G. Bönnemann, Coen A.C. Ottenheijm
Cholangiopathies caused by biliary epithelial cell (BEC) injury represent a leading cause of liver failure. No effective pharmacologic therapies exist, and the underlying mechanisms remain obscure. We aimed to explore the mechanisms of bile duct repair after targeted BEC injury. Injection of intermedilysin into BEC-specific human CD59 (hCD59) transgenic mice induced acute and specific BEC death, representing a model to study the early signals that drive bile duct repair. Acute BEC injury induced cholestasis followed by CCR2+ monocyte recruitment and BEC proliferation. By using microdissection and next generation RNA sequencing, we identified five genes that were most upregulated in proliferating BECs after acute injury including Mapk8ip2, Cdkn1a, Itgb6, Rgs4, and Ccl2. Immunohistochemistry analyses confirmed robust upregulation of integrin αvβ6 (ITGβ6) expression in this BEC injury model, after bile duct ligation, and in patients with chronic cholangiopathies. Deletion of Itgb6 gene attenuated BEC proliferation post-acute bile duct injury. Macrophage depletion or Ccr2-deficiency impaired ITGβ6 expression and BEC proliferation. In vitro experiments revealed that bile-acid activated monocytes promoted BEC proliferation through ITGβ6. Our data suggest that BEC injury induces cholestasis, monocyte recruitment, and induction of ITGβ6, which work together to promote BEC proliferation, and that therefore represent potential therapeutic targets for cholangiopathies.
Adrien Guillot, Lucia Guerri, Dechun Feng, Seung-Jin Kim, Yeni Ait Ahmed, Janos Paloczi, Yong He, Kornel Schuebel, Shen Dai, Fengming Liu, Pal Pacher, Tatiana Kisseleva, Xuebin Qin, David Goldman, Frank Tacke, Bin Gao
Several COVID-19 studies have focused on neuropathology. In this issue of the JCI, Qin, Wu, and Chen, et al. focused specifically on people whose acute infection lacked obvious neurological involvement. Severely infected patients showed abnormal grey matter volumes, white matter diffusion, and cerebral blood flow compared with healthy controls and those with mild infection. The data remain associative rather than mechanistic, but correlations with systemic immune markers suggest effects of inflammation, hypercoagulation, or other aspects of disease severity. Mechanistic research is warranted. Given the lack of obvious neurological symptoms, neurocognitive assessments were not performed, but the findings suggest that such assessments may be warranted in severely affected patients, even without obvious symptoms. Further, studying CNS involvement of other disorders with overlapping pathophysiologies, such as inflammation, coagulation, hypoxia, or direct viral infection may reveal the causes for COVID-19 related neuropathology.
Amit Mahajan, Graeme F. Mason
Multisystem Inflammatory Syndrome in Children (MIS-C), a hyperinflammatory syndrome associated with SARS-CoV-2 infection, shares clinical features with toxic shock syndrome, which is triggered by bacterial superantigens. Superantigen specificity for different Vβ-chains results in Vβ-skewing, whereby T cells with specific Vβ-chains and diverse antigen specificity are overrepresented in the TCR repertoire. Here, we characterized the TCR repertoire of MIS-C patients and found a profound expansion of TCR Βeta Variable gene (TRBV)11-2, with up to 24% of clonal T cell space occupied by TRBV11-2 T cells, which correlated with MIS-C severity and serum cytokine levels. Analysis of TRBJ gene usage and CDR3 length distribution of MIS-C expanded TRBV11-2 clones revealed extensive junctional diversity. Patients with TRBV11-2 expansion showed HLA class I allele restriction to HLA-I A02, C35 and C04, indicating a novel mechanism for CDR3-independent T cell expansion. In silico modelling indicated that polyacidic residues in the Vβ chain encoded by TRBV11-2 strongly interact with the superantigen-like motif of SARS-CoV-2 spike glycoprotein, suggesting that unprocessed SARS-CoV-2 spike may directly mediate TRBV11-2 expansion. Overall, our data indicate that a CDR3-independent interaction between SARS-CoV-2 spike and TCR leads to T cell expansion and possibly activation, which may account for the clinical presentation of MIS-C.
Rebecca A. Porritt, Lisa Paschold, Magali Noval Rivas, Mary Hongying Cheng, Lael M. Yonker, Harsha Chandnani, Merrick Lopez, Donjete Simnica, Christoph Schultheiß, Chintda Santiskulvong, Jennifer van Eyk, John K. McCormick, Alessio Fasano, Ivet Bahar, Mascha Binder, Moshe Arditi
Melanomas commonly undergo a phenotype switch, from a proliferative to an invasive state. Such tumor cell plasticity contributes to immunotherapy resistance, however, the mechanisms are not completely understood and thus therapeutically unexploited. Using melanoma mouse models, we demonstrated that blocking the MNK1/2-eIF4E axis inhibited melanoma phenotype switching and sensitized melanoma to anti-PD-1 immunotherapy. We showed that phospho-eIF4E-deficient murine melanomas expressed high levels of melanocytic antigens, with similar results verified in patient melanomas. Mechanistically, we identified phospho-eIF4E-mediated translational control of NGFR, a critical effector of phenotype switching. Genetic ablation of phospho-eIF4E reprogrammed the immunosuppressive microenvironment, exemplified by lowered production of inflammatory factors, decreased PD-L1 expression on dendritic cells and MDSCs, and increased CD8+ T-cell infiltrates. Finally, dual blockade of the MNK1/2-eIF4E axis and the PD-1/PD-L1 immune checkpoint demonstrated efficacy in multiple melanoma models regardless of their genomic classification. An increase in the presence of intratumoral stem-like TCF1+PD-1+CD8+ T cells, a characteristic essential for durable anti-tumor immunity, was detected in mice administered a MNK1/2 inhibitor and anti-PD-1 therapy. Using MNK1/2 inhibitors to repress phospho-eIF4E thus offers a new strategy to inhibit melanoma plasticity and improve response to anti-PD-1 immunotherapy.
Fan Huang, Christophe Goncalves, Margarita Bartish, Joelle Rémy-Sarrazin, Mark E. Issa, Brendan Cordeiro, Qianyu Guo, Audrey Emond, Mikhael Attias, William Yang, Dany Plourde, Jie Su, Marina Godoy Gimeno, Yao Zhan, Alba Galán, Tomasz Rzymski, Milena Mazan, Magdalena Masiejczyk, Jacek Faber, Elie Khoury, Alexandre Benoit, Natascha Gagnon, David Dankort, Fabrice Journe, Ghanem Ghanem, Connie M. Krawczyk, H. Uri Saragovi, Ciriaco A. Piccirillo, Nahum Sonenberg, Ivan Topisirovic, Christopher E. Rudd, Wilson H. Miller Jr., Sonia V. del Rincón
Although cancer cells are frequently faced with nutrient- and oxygen-poor microenvironment, elevated hexosamine-biosynthesis pathway (HBP) activity and protein O-GlcNAcylation (a nutrient sensor) contribute to rapid growth of tumor and are emerging hallmarks of cancer. Inhibiting O-GlcNAcylation could be a promising anti-cancer strategy. The gluconeogenic enzymes phosphoenolpyruvate carboxykinase 1 (PCK1) was downregulated in hepatocellular carcinoma (HCC). However, little is known about the potential role of PCK1 in enhanced HBP activity and HCC carcinogenesis under glucose-limited conditions. In this study, PCK1 knockout markedly enhanced the global O-GlcNAcylation levels under low glucose condition. Mechanistically, metabolic reprogramming in PCK1-loss hepatoma cells led to oxaloacetate accumulation and increased de novo UTP synthesis contributing to uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) biosynthesis. Meanwhile, deletion of PCK1 also resulted in AMPK-GFAT1 axis inactivation promoting UDP-GlcNAc synthesis for elevated O-GlcNAcylation. Notably, lower expression of PCK1 promoted CHK2 threonine 378 O-GlcNAcylation counteracting its stability and dimer formation, increasing CHK2-dependent Rb phosphorylation and HCC cell proliferation. Moreover, aminooxyacetic acid hemihydrochloride and 6-diazo-5-oxo-L-norleucine blocked HBP-mediated O-GlcNAcylation and suppressed tumor progression in liver-specific Pck1-knockout mice. We reveal a link between PCK1 depletion and hyper-O-GlcNAcylation that underlies HCC oncogenesis and suggest therapeutic targets for HCC that act by inhibiting O-GlcNAcylation.
Jin Xiang, Chang Chen, Rui Liu, Dongmei Gou, Lei Chang, Haijun Deng, Qingzhu Gao, Wanjun Zhang, Lin Tuo, Xuanming Pan, Li Liang, Jie Xia, Luyi Huang, Ke Yao, Bohong Wang, Zeping Hu, Ailong Huang, Kai Wang, Ni Tang
X-linked adrenoleukodystrophy (ALD) is a progressive neurodegenerative disease caused by mutations in ABCD1, the peroxisomal very long-chain fatty acid (VLCFA) transporter. ABCD1 deficiency results in accumulation of saturated VLCFAs. A drug screen using a phenotypic motor assay in a zebrafish ALD model identified chloroquine as the top hit. Chloroquine increased expression of stearoyl-CoA desaturase-1 (scd1), the enzyme mediating fatty acid saturation status, suggesting that a shift towards mono-unsaturated fatty acids relieved toxicity. In human ALD fibroblasts chloroquine also increased SCD1 levels and reduced saturated VLCFAs. Conversely, pharmacological inhibition of SCD1 expression led to an increase in saturated VLCFAs, and CRISPR knockout of scd1 in zebrafish mimicked the motor phenotype of ALD zebrafish. Importantly, saturated VLCFAs caused ER stress in ALD fibroblasts whereas mono-unsaturated VLCFA did not. In parallel, we used liver X receptor (LXR) agonists to increase SCD1 expression, causing a shift from saturated towards mono-unsaturated VLCFA, and normalizing phospholipid profiles. Finally, Abcd1-/y mice receiving LXR agonist in their diet had VLCFA reductions in ALD-relevant tissues. These results suggest that metabolic rerouting of saturated to mono-unsaturated VLCFAs may alleviate lipid toxicity, a strategy that may be beneficial in ALD and other peroxisomal diseases in which VLCFAs play a key role.
Quentin Raas, Malu-Clair van de Beek, Sonja Forss-Petter, Inge M.E. Dijkstra, Abigail DeSchiffart, Briana C. Freshner, Tamara J. Stevenson, Yorrick R.J. Jaspers, Liselotte M. Nagtzaam, Ronald J.A. Wanders, Michel van Weeghel, Joo-Yeon Engelen-Lee, Marc Engelen, Florian Eichler, Johannes Berger, Joshua L. Bonkowsky, Stephan Kemp
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