Commentary
Abstract
Group B Streptococcus (GBS) is an important cause of infections, including meningitis. The molecular events underlying its pathogenesis are poorly understood. A study in this issue of the JCI reports that the GBS invasion-associated gene (iagA) contributes to meningeal infection and virulence by facilitating invasion of the cells that compose the blood-brain barrier and of other host cells. The mechanism involved most likely relates to the gene product’s role in synthesis of a glycolipid anchor for a bacterial cell-surface entity that interacts directly with host cells.
Authors
Miriam J. Baron, Dennis L. Kasper
Abstract
Invariant natural killer T (iNKT) cells are T lymphocytes that behave similarly to cells of the innate immune system. The glycolipid α-galactosylceramide (α-GalCer) is a potent and specific activator of mouse and human iNKT cells and has been used in cancer clinical trials to drive NKT cell–mediated immune responses. However, little is known about the dynamics of the iNKT cell response to α-GalCer in vivo. In this issue of the JCI, Parekh and colleagues demonstrate that administration of α-GalCer causes iNKT cells to become unresponsive, for at least 1 month, in mice. This leads us to ask, should sequential administration of α-GalCer still be used to activate iNKT cells given the anergic state it has been shown here to induce? This intriguing article raises the issue of the avoidance of anergy induction in the design of treatment regimens that use α-GalCer as a specific activator of iNKT cells.
Authors
Barbara A. Sullivan, Mitchell Kronenberg
Abstract
Akt is an important signaling molecule that modulates many cellular processes such as cell growth, survival, and metabolism. Akt activation has been proposed as a potential strategy for increasing cardiomyocyte survival following ischemia. In mammalian cells, 3 distinct isoforms of Akt exist, but their precise roles in cardiovascular biology were previously unknown. Three separate studies published in this issue of the JCI now provide important new insight into the central role of Akt1 in the regulation of angiogenesis and the maladaptive or deleterious consequences of chronic unregulated Akt activation in the heart (see the related articles beginning on pages 2108, 2119, and 2128). Here we discuss the implications of these exciting new studies.
Authors
Brian T. O’Neill, E. Dale Abel
Abstract
Reports of neoplasia related to insertional activation of protooncogenes by retroviral vectors have raised serious safety concerns in the field of gene therapy. Modification of current approaches is urgently required to minimize the deleterious consequences of insertional mutagenesis. In this issue of the JCI, Adjali and colleagues report on their treatment of SCID mice lacking the 70-kDa protein tyrosine kinase, ZAP-70, with direct intrathymic injection of a ZAP-70–expressing T cell–specific lentiviral vector, which resulted in T cell reconstitution. Using lentiviral vectors and in situ gene transfer may represent a safer approach than using retroviral vectors for ex vivo gene transfer into HSCs, avoiding 3 factors potentially linked to leukemogenesis, namely HSC targets, ex vivo transduction and expansion, and standard Moloney leukemia virus–based retroviral vectors.
Authors
Ruth Seggewiss, Cynthia E. Dunbar
Abstract
While the release of pollen into the air is essential for the reproduction of plants, the accidental yet inevitable uptake of pollen into human airways can cause symptoms of seasonal allergies and asthma. The symptomatic response to pollen is caused by granulocytes that produce inflammation, which is due in part to oxidative stress through the action of NADPH oxidases. The recruitment of these inflammatory granulocytes was previously thought to depend entirely on the activation of an adaptive immune response. In this issue of the JCI, Boldogh et al. demonstrate that pollens contain endogenous NADPH oxidase activity, which functions to generate local “danger signals” in nearby airway epithelium. These signals in turn trigger the early recruitment of granulocytes, even in the absence of the adaptive immune response. These findings suggest that inhibition of the pollen oxidase may provide a way to antagonize allergic inflammation at a very early step.
Authors
Darren R. Ritsick, J. David Lambeth
Abstract
The discovery of the antiinflammatory effect of insulin and the proinflammatory effect of glucose has not only provided novel insight into the mechanisms underlying several disease states but has also provided a rationale for the treatment of hyperglycemia in several acute clinical conditions. Van den Berghe et al. previously showed the benefits of intensive glycemic control with insulin in patients admitted to intensive care units. In this issue of the JCI, the same group of investigators now demonstrates that infusion of insulin to restore euglycemia in these patients results in a marked reduction in inflammatory indices such as adhesion molecules, hepatic iNOS, and plasma NO metabolites. The reduction in the mediators of inflammation may thus be responsible for the impressive improvement in clinical outcomes following insulin therapy, and the results suggest a new paradigm in which glucose and insulin are related not only through their metabolic actions but also through their opposite effects on inflammatory mechanisms.
Authors
Paresh Dandona, Priya Mohanty, Ajay Chaudhuri, Rajesh Garg, Ahmad Aljada
Abstract
Macrophage scavenger receptors, such as CD36 and class A scavenger receptor (SR-A), have previously been thought to play a central role in foam cell formation and atherogenesis by mediating the uptake of oxidized LDL. In this issue of the JCI, Moore et al. report that Apoe–/– mice deficient in either CD36 or SR-A did not have less atherosclerosis at the level of the aortic valve than did wild-type Apoe–/– mice. In contrast, similar studies by previous investigators found that deletion of these receptors decreased atherogenesis. The reasons for the different results are not known, but these data suggest that the role of these receptors in atherogenesis remains unresolved.
Authors
Joseph L. Witztum
Abstract
Bile acids are natural detergents that assist in the absorption and digestion of fats in the intestine. In liver, the synthesis of bile acids from cholesterol is regulated by multiple signaling cascades that repress transcription of the gene encoding cholesterol 7α-hydroxylase (CYP7A1), the rate-limiting enzyme in the classic bile acid synthesis pathway. In this issue of the JCI, Ito and coworkers demonstrate that mice lacking βKlotho, a membrane protein with 2 putative glycosidase domains, have increased Cyp7a1 mRNA levels and bile acid concentrations. βKlotho-KO mice also have small gallbladders and are resistant to cholesterol gallstone formation. These findings highlight the central role of βKlotho in bile acid homeostasis and raise the possibility that this protein could be a pharmacologic target for the treatment of gallstones.
Authors
Antonio Moschetta, Steven A. Kliewer
Abstract
The distinction between peptides that bind to class II MHC products under laboratory conditions and those that do so physiologically is important for the prediction of antigens recognized by autoreactive T cells. In this issue of the JCI, Suri et al., using antigen-presenting cells, compared the peptides that bound to human HLA-DQ8 and those that bound to mouse I-Ag7, both class II MHC products that predispose their carriers to type 1 diabetes. The rules of engagement for the peptide ligands of the DQ8 and I-Ag7 molecules involve similarities in their anchor residues, which mediate stable interaction with class II MHC products. The peptides identified derive from overlapping sets of self proteins.
Authors
Hidde L. Ploegh
Abstract
Recently, mutations causing juvenile hemochromatosis have been identified in a novel gene, hemojuvelin (HJV), located on chromosome 1. Mouse models of this disease have now been developed by 2 groups, Huang et al. and Niederkofler et al., through targeted disruption of the Hjv gene (see the related articles beginning on pages 2180 and 2187). These mutant mice will allow further investigation into the role of HJV in the regulation of iron homeostasis, a role that to date remains elusive.
Authors
Sophie Vaulont, Dan-Qing Lou, Lydie Viatte, Axel Kahn
No posts were found with this tag.
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)