editorials 1. Stetson DB, Medzhitov R. Recognition of cytosolic DNA ac-
tivates an IRF3-dependent innate immune response. Immunity 2006;24:93-103. 2. Ishii KJ, Coban C, Kato H, et al. A Toll-like receptor-independent antiviral response induced by double-stranded B-form DNA. Nat Immunol 2006;7:40-8. [Erratum, Nat Immunol 2006;7:427.] 3. Ishikawa H, Barber GN. STING is an endoplasmic reticulum adaptor that facilitates innate immune signalling. Nature 2008; 455:674-8. [Erratum, Nature 2008;456:274.] 4. Sun L, Wu J, Du F, Chen X, Chen ZJ. Cyclic GMP-AMP synthase is a cytosolic DNA sensor that activates the type I interferon pathway. Science 2013;339:786-91. 5. Wu J, Sun L, Chen X, et al. Cyclic GMP-AMP is an endogenous second messenger in innate immune signaling by cytosolic DNA. Science 2013;339:826-30. 6. Liu Y, Jesus AA, Marrero B, et al. Activated STING in a vascular and pulmonary syndrome. N Engl J Med 2014;371:507-18. 7. Lafaille FG, Pessach IM, Zhang SY, et al. Impaired intrinsic
immunity to HSV-1 in human iPSC-derived TLR3-deficient CNS cells. Nature 2012;491:769-73. 8. Rice GI, del Toro Duany Y, Jenkinson EM, et al. Gain-offunction mutations in IFIH1 cause a spectrum of human disease phenotypes associated with upregulated type I interferon signaling. Nat Genet 2014;46:503-9. 9. Liu L, Okada S, Kong XF, et al. Gain-of-function human STAT1 mutations impair IL-17 immunity and underlie chronic mucocutaneous candidiasis. J Exp Med 2011;208:1635-48. 10. Gall A, Treuting P, Elkon KB, et al. Autoimmunity initiates in nonhematopoietic cells and progresses via lymphocytes in an interferon-dependent autoimmune disease. Immunity 2012;36: 120-31. 11. Crow YJ. Type I interferonopathies: a novel set of inborn errors of immunity. Ann N Y Acad Sci 2011;1238:91-8. DOI: 10.1056/NEJMe1407246 Copyright © 2014 Massachusetts Medical Society.
Shaken, Not Sonicated? Colin L. Masters, M.D. Investigators studying the infectious protein (prion protein, PrP) have long sought a sensitive and minimally invasive diagnostic tool that is specifically targeted to the particular protein that causes the disease. For all forms of Creutzfeldt–Jakob disease — sporadic, inherited, and acquired — such diagnostic tools are emerging, as illustrated by two similar technologies now reported in the Journal by Orrú et al.1 and Moda et al.2: a real-time quaking (shaking)- induced conversion (RT-QuIC) assay applied to nasal olfactory epithelial brushings1 and a sonicated protein misfolding cyclic amplification (PMCA) assay applied to urine.2 Both assays rely on imparting kinetic energy into a pathway in which very small amounts of misfolded protein seeds (abnormal conformers) are amplified into larger amyloidogenic or protease-resistant protein aggregates. Although future research will shed light on the relative merits of RT-QuIC and PMCA, the sensitivity (93 to 97%) and specificity (100%) reported in these preliminary studies are encouraging, especially considering that the assays may detect amounts as small as 40 to 100 oligomers of misfolded seed per milliliter. A major issue with these tests is the propensity of the native protein to convert itself into β-sheet rich oligomers and fibrils in the absence of abnormal seeds,3 giving rise to “breakthrough” false positive results. Moreover, although the
specificity was reported as 100% in both studies, we do not yet have precise estimates of the specificities of the tests, as indicated by the wide confidence intervals. Creutzfeldt–Jakob disease is extremely uncommon, and a test without near-perfect specificity may also result in many false positive results if it is applied to patients with a low probability of having the disease. In these circumstances, it is important to highlight the preliminary nature of these studies. Detection of abnormal PrP seeds in olfactory mucosal brushings at concentrations equivalent to those in diseased brain, and several logs greater than those in cerebrospinal fluid, may have implications for infection control. There is no epidemiologic evidence of nasal or aerosolborne transmission of sporadic Creutzfeldt– Jakob disease, but Orrú et al. point to recent evidence that these pathways are highly effective in experimental models. Some experts have recommended appropriate decontamination of surgical instruments that come into contact with the olfactory epithelium of patients at high risk for Creutzfeldt–Jakob disease.4 In contrast, detection of low amounts of abnormal PrP seeds in the urine of patients with variant Creutzfeldt–Jakob disease caused by exposure to bovine spongiform encephalopathy (and not in the urine of patients with other forms of Creutzfeldt–Jakob disease) confirms the
n engl j med 371;6 nejm.org august 7, 2014
The New England Journal of Medicine Downloaded from nejm.org at EMORY UNIVERSITY on August 6, 2015. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
571
editorials
widespread dispersal of the variant Creutzfeldt– Jakob disease prion throughout the body. The PMCA assay is also showing promise for the detection of variant Creutzfeldt–Jakob disease prion protein in blood.5 These assays that use shaking or sonication inputs with amyloid or protease-resistance outputs may prove to be extremely useful in the diagnosis of other protein-aggregation diseases. Most important will be the detection of the abnormal conformers of the amyloid beta (Aβ) peptide, which lies at the center of Alzheimer’s disease.6 Preliminary data from Salvadores et al. (i.e., Soto’s laboratory) show a sensitivity of 90% and a specificity of 92% for a test that amplifies Aβ oligomers from cerebrospinal fluid.7 Surprisingly, in this scenario, shaking performed better than sonication, perhaps reflecting the more fragile nature of Aβ oligomers as compared with abnormal PrP seeds. Perhaps these structural properties also relate in some way to the lack of transmissibility of Alzheimer’s disease, as compared with Creutzfeldt–Jakob disease. Ian Fleming’s Bond8 would be pleased to learn of this added dimension to “shaken, not stirred.”
Disclosure forms provided by the author are available with the full text of this article at NEJM.org. From the Florey Institute of Neuroscience and Mental Health, the University of Melbourne, Melbourne, VIC, Australia. 1. Orrú CD, Bongianni M, Tonoli G, et al. A test for Creutzfeldt–
Jakob disease using nasal brushings. N Engl J Med 2014;371:51929. 2. Moda F, Gambetti P, Notari S, et al. Prions in the urine of patients with variant Creutzfeldt–Jakob disease. N Engl J Med 2014;371:530-9. 3. Ladner-Keay CL, Griffith BJ, Wishart DS. Shaking alone induces de novo conversion of recombinant prion proteins to β-sheet rich oligomers and fibrils. PLoS One 2014;9(6):e98753. 4. Sethi N, Kane J, Condon L. Creutzfeldt-Jakob disease and ENT. J Laryngol Otol 2013;127:1050-5. 5. Lacroux C, Comoy E, Moudjou M, et al. Preclinical detection of variant CJD and BSE prions in blood. PLoS Pathog 2014;10(6): e1004202. 6. Masters CL, Selkoe DJ. Biochemistry of amyloid β-protein and amyloid deposits in Alzheimer disease. In: Selkoe DJ, Mandelkow E, Holtzman DM, eds. The biology of Alzheimer’s disease. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press, 2012:181-204. 7. Salvadores N, Shahnawaz M, Scarpini E, Tagliavini F, Soto C. Detection of misfolded Aβ oligomers for sensitive biochemical diagnosis of Alzheimer’s disease. Cell Rep 2014;7:261-8. 8. Fleming I. Diamonds are forever. London: Jonathan Cape, 1956. DOI: 10.1056/NEJMe1407419 Copyright © 2014 Massachusetts Medical Society.
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572
n engl j med 371;6 nejm.org august 7, 2014
The New England Journal of Medicine Downloaded from nejm.org at EMORY UNIVERSITY on August 6, 2015. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
tivates an IRF3-dependent innate immune response. Immunity 2006;24:93-103. 2. Ishii KJ, Coban C, Kato H, et al. A Toll-like receptor-independent antiviral response induced by double-stranded B-form DNA. Nat Immunol 2006;7:40-8. [Erratum, Nat Immunol 2006;7:427.] 3. Ishikawa H, Barber GN. STING is an endoplasmic reticulum adaptor that facilitates innate immune signalling. Nature 2008; 455:674-8. [Erratum, Nature 2008;456:274.] 4. Sun L, Wu J, Du F, Chen X, Chen ZJ. Cyclic GMP-AMP synthase is a cytosolic DNA sensor that activates the type I interferon pathway. Science 2013;339:786-91. 5. Wu J, Sun L, Chen X, et al. Cyclic GMP-AMP is an endogenous second messenger in innate immune signaling by cytosolic DNA. Science 2013;339:826-30. 6. Liu Y, Jesus AA, Marrero B, et al. Activated STING in a vascular and pulmonary syndrome. N Engl J Med 2014;371:507-18. 7. Lafaille FG, Pessach IM, Zhang SY, et al. Impaired intrinsic
immunity to HSV-1 in human iPSC-derived TLR3-deficient CNS cells. Nature 2012;491:769-73. 8. Rice GI, del Toro Duany Y, Jenkinson EM, et al. Gain-offunction mutations in IFIH1 cause a spectrum of human disease phenotypes associated with upregulated type I interferon signaling. Nat Genet 2014;46:503-9. 9. Liu L, Okada S, Kong XF, et al. Gain-of-function human STAT1 mutations impair IL-17 immunity and underlie chronic mucocutaneous candidiasis. J Exp Med 2011;208:1635-48. 10. Gall A, Treuting P, Elkon KB, et al. Autoimmunity initiates in nonhematopoietic cells and progresses via lymphocytes in an interferon-dependent autoimmune disease. Immunity 2012;36: 120-31. 11. Crow YJ. Type I interferonopathies: a novel set of inborn errors of immunity. Ann N Y Acad Sci 2011;1238:91-8. DOI: 10.1056/NEJMe1407246 Copyright © 2014 Massachusetts Medical Society.
Shaken, Not Sonicated? Colin L. Masters, M.D. Investigators studying the infectious protein (prion protein, PrP) have long sought a sensitive and minimally invasive diagnostic tool that is specifically targeted to the particular protein that causes the disease. For all forms of Creutzfeldt–Jakob disease — sporadic, inherited, and acquired — such diagnostic tools are emerging, as illustrated by two similar technologies now reported in the Journal by Orrú et al.1 and Moda et al.2: a real-time quaking (shaking)- induced conversion (RT-QuIC) assay applied to nasal olfactory epithelial brushings1 and a sonicated protein misfolding cyclic amplification (PMCA) assay applied to urine.2 Both assays rely on imparting kinetic energy into a pathway in which very small amounts of misfolded protein seeds (abnormal conformers) are amplified into larger amyloidogenic or protease-resistant protein aggregates. Although future research will shed light on the relative merits of RT-QuIC and PMCA, the sensitivity (93 to 97%) and specificity (100%) reported in these preliminary studies are encouraging, especially considering that the assays may detect amounts as small as 40 to 100 oligomers of misfolded seed per milliliter. A major issue with these tests is the propensity of the native protein to convert itself into β-sheet rich oligomers and fibrils in the absence of abnormal seeds,3 giving rise to “breakthrough” false positive results. Moreover, although the
specificity was reported as 100% in both studies, we do not yet have precise estimates of the specificities of the tests, as indicated by the wide confidence intervals. Creutzfeldt–Jakob disease is extremely uncommon, and a test without near-perfect specificity may also result in many false positive results if it is applied to patients with a low probability of having the disease. In these circumstances, it is important to highlight the preliminary nature of these studies. Detection of abnormal PrP seeds in olfactory mucosal brushings at concentrations equivalent to those in diseased brain, and several logs greater than those in cerebrospinal fluid, may have implications for infection control. There is no epidemiologic evidence of nasal or aerosolborne transmission of sporadic Creutzfeldt– Jakob disease, but Orrú et al. point to recent evidence that these pathways are highly effective in experimental models. Some experts have recommended appropriate decontamination of surgical instruments that come into contact with the olfactory epithelium of patients at high risk for Creutzfeldt–Jakob disease.4 In contrast, detection of low amounts of abnormal PrP seeds in the urine of patients with variant Creutzfeldt–Jakob disease caused by exposure to bovine spongiform encephalopathy (and not in the urine of patients with other forms of Creutzfeldt–Jakob disease) confirms the
n engl j med 371;6 nejm.org august 7, 2014
The New England Journal of Medicine Downloaded from nejm.org at EMORY UNIVERSITY on August 6, 2015. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
571
editorials
widespread dispersal of the variant Creutzfeldt– Jakob disease prion throughout the body. The PMCA assay is also showing promise for the detection of variant Creutzfeldt–Jakob disease prion protein in blood.5 These assays that use shaking or sonication inputs with amyloid or protease-resistance outputs may prove to be extremely useful in the diagnosis of other protein-aggregation diseases. Most important will be the detection of the abnormal conformers of the amyloid beta (Aβ) peptide, which lies at the center of Alzheimer’s disease.6 Preliminary data from Salvadores et al. (i.e., Soto’s laboratory) show a sensitivity of 90% and a specificity of 92% for a test that amplifies Aβ oligomers from cerebrospinal fluid.7 Surprisingly, in this scenario, shaking performed better than sonication, perhaps reflecting the more fragile nature of Aβ oligomers as compared with abnormal PrP seeds. Perhaps these structural properties also relate in some way to the lack of transmissibility of Alzheimer’s disease, as compared with Creutzfeldt–Jakob disease. Ian Fleming’s Bond8 would be pleased to learn of this added dimension to “shaken, not stirred.”
Disclosure forms provided by the author are available with the full text of this article at NEJM.org. From the Florey Institute of Neuroscience and Mental Health, the University of Melbourne, Melbourne, VIC, Australia. 1. Orrú CD, Bongianni M, Tonoli G, et al. A test for Creutzfeldt–
Jakob disease using nasal brushings. N Engl J Med 2014;371:51929. 2. Moda F, Gambetti P, Notari S, et al. Prions in the urine of patients with variant Creutzfeldt–Jakob disease. N Engl J Med 2014;371:530-9. 3. Ladner-Keay CL, Griffith BJ, Wishart DS. Shaking alone induces de novo conversion of recombinant prion proteins to β-sheet rich oligomers and fibrils. PLoS One 2014;9(6):e98753. 4. Sethi N, Kane J, Condon L. Creutzfeldt-Jakob disease and ENT. J Laryngol Otol 2013;127:1050-5. 5. Lacroux C, Comoy E, Moudjou M, et al. Preclinical detection of variant CJD and BSE prions in blood. PLoS Pathog 2014;10(6): e1004202. 6. Masters CL, Selkoe DJ. Biochemistry of amyloid β-protein and amyloid deposits in Alzheimer disease. In: Selkoe DJ, Mandelkow E, Holtzman DM, eds. The biology of Alzheimer’s disease. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press, 2012:181-204. 7. Salvadores N, Shahnawaz M, Scarpini E, Tagliavini F, Soto C. Detection of misfolded Aβ oligomers for sensitive biochemical diagnosis of Alzheimer’s disease. Cell Rep 2014;7:261-8. 8. Fleming I. Diamonds are forever. London: Jonathan Cape, 1956. DOI: 10.1056/NEJMe1407419 Copyright © 2014 Massachusetts Medical Society.
early job alert service available at the nejm careercenter
Register to receive weekly e-mail messages with the latest job openings that match your specialty, as well as preferred geographic region, practice setting, call schedule, and more. Visit the NEJM CareerCenter at NEJMjobs.org for more information.
572
n engl j med 371;6 nejm.org august 7, 2014
The New England Journal of Medicine Downloaded from nejm.org at EMORY UNIVERSITY on August 6, 2015. For personal use only. No other uses without permission. Copyright © 2014 Massachusetts Medical Society. All rights reserved.
