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Quantitative estimates of Thioflavin S-positive Aβ CP affecting the cerebral cortex in subjects with iCJD and sporadic AD (sAD). A: the density of Aβ CP, expressed as the percentage of cerebral cortex area occupied, was 5 times greater in subjects with sAD than in iCJD. B: size of Aβ CP (N=500), expressed as diameter, was greater in patients with sAD than in those with iCJD. C and D: representative microscopic fields showing fewer and smaller CP (arrows) in iCJD (C) than sAD (D) where cluster of very large CP (dashed square) could be detected. Bar graphs are expressed as mean ± standard error of the mean (SEM) in A or as mean ± standard deviation in B. Student's t-test (two-tailed). (PDF 3338 kb)

Size of blood vessels examined and semiquantitative evaluation of the percentage of the vessel wall perimeters occupied by Aβ deposits in subjects with iCJD and sporadic AD (sAD). A: scatter plot showing the similar sizes of the blood vessels from the subarachnoid spaces of frontal, occipital and cerebellar regions examined for the semiquantitative determinations made in B; size of individual vessels is measured as perimeter. B: the percentage of the blood vessel wall occupied by Aβ was significantly greater in iCJD than sAD. Bar graphs are expressed as mean±SEM. Student's t-test (two-tailed). (PDF 228 kb)

Histopathology of an atypical US iCJD (case 5, Table 1). A-C: HE staining. D and E: PrP immunohistochemistry. A: spongiform degeneration (SD) with large and confluent vacuoles typical of the sCJDMM2 subtype, but limited to layer II of the frontal cortex, and severe neuronal loss and gliosis affecting all layers. B: high magnification of the area highlighted in A showing SD with large vacuoles. C: severe loss of granule cells and gliosis of the cerebellum; Grl. L: granular layer; Mol. L: molecular layer. D and E: diffuse or “synaptic” PrP immunostaining in the frontal cortex (D), and molecular and granular layers of the cerebellum (E); A-C: HE staining. D and E: PrP immunohistochemistry with Ab 3F4. (PDF 30981 kb)

Kaplan–Meier estimates of iCJD and sCJD controls. A: survival graphs representing whole iCJD cohort and its GH- and DM-iCJD subsets as well as sCJD cases. B: survival graphs of 21 iCJD and all sCJD divided into two groups according to age: 54 years or younger (≤54y), and older than 54 years (> 54y). Median survivals are indicated on the X-axis in A and B (arrowheads). Significant differences in median survivals, determined by the log rank (Mantel-Cox), were found between GH-iCJD and sCJD (P=0.0017) (A) or DM-iCJD ≤ 54y and sCJD ≤ 54y (P=0.0027) (B). (PDF 2348 kb)

WB profile of resPrPSc from iCJD and sCJD controls using different WB systems for PrP detection. BHs from the frontal cortex (lanes 8-10) and cerebellum (lanes 1-7) treated with 100 U/ml PK (~2000 μg/ml) were probed with indicated Abs. PrP bands were resolved in 15% Tris-HCl, 8.7 cm-long (A-C and E) and 20 cm-long (D) gels, and visualized with near-infrared LI-COR system (A-D and E(i)) or chemiluminescence (E(ii) and E(iii)). A: profiles of resPrPSc from CJD obtained with an 8.7 cm-long gel are similar to those obtained with the 20 cm-long gels in Fig. 2. The unglycosylated resPrPSc ~21 kDa of type 1 (21), ~20 kDa of type i (i), ~19 kDa of type 2 (2) and ~18 kDa (18) are indicated. B: the ~20 kDa of type i (i) and ~21 kDa of type 1 (21) (lanes 3-8), but not the ~19 kDa band of type 2, immunoreact with Ab 12B2. Profile of resPrPSc from iCJDMMi (lane 5) is indistinguishable from that of CJDMVi+2 (lanes 3 and 4), but differs from those of iCJDMM1 and sCJDMM1 (lanes 6-8), as the ~21 kDa band predominates in these three conditions. C: only ~19 kDa (type 2), but not ~21 kDa (type 1) and ~20 kDa (type i) immunoreacted with Tohoku-2 (To-2). An ~18 kDa (18) band in CJDVV2 and CJDMVi+2, and an unidentified lower size fragment (large arrow) in all cases harboring type 2 were also detected. A non-specific band (indicated by three asterisks) was present in all tested samples. D: high resolution gel electrophoresis in 20-cm long gel revealing ~21 kDa (21) and the ~20 kDa band (i and arrowhead). E(i): enhanced image of dashed area in A showing the bands ~21 kDa (21), ~20 kDa (i and arrowhead), and ~19 kDa (19; lane 4). The detection of the resPrPSc ~20 kDa band in addition to the prominent ~21 kDa fragment in CJDMM1 is most likely due to our use of a high resolution electrophoretic systems. E(ii): profiles of unglycosylated resPrPSc from the same cases in E(i) visualized on film by chemiluminescence. Note that the three CJDMM1 (lanes 6-8) show only ~21 kDa bands. E(iii): the ~20 kDa and ~21 kDa bands visible in B (lanes 3-5) resolve as a single band of ~21 kDa (lanes 4 and 5) when visualized on film by chemiluminescence. (PDF 6122 kb)

Figure S1. Aβ, TDP-43 and PrP immunoreactivity in CTE Cases 1–3. a: Widespread Aβ deposits in the subpial surface (arrow) and core dense Aβ plaques (arrowhead) in the frontal cortex. b: TDP-43 cytoplasmic inclusions (arrow) and “dot-like” structures (arrowhead) in the hippocampus. c and d: Plaque-like PrP deposits (arrow in c) and intense PrP immunoreactivity in the subcortical white matter of the temporal lobe. e and f: Granular Aβ deposits (e) and diffuse Aβ plaques (f) in the parietal (e) and frontal (f) cortices; e, inset: a rare core dense Aβ plaque. Abs: 4G8 (a, e, f), TDP-43 in (b), 3F4 (c and d). Scalebar inset in e: 20 μm. (PDF 3628 kb)

Table S1. Molecular classification of sCJD subtypes [8, 15]. Table S2 showing sex, sCJD subtype, age at onset and death, disease duration in study cases and respective controls. (DOCX 17 kb)

Prevalence of Aβ and tau pathologies in iCJD and sCJD used as controls. Table S5. Aβ diffuse plaque staging in cases of iCJD and sCJD not associated with Aβ CP pathology. Table S6. Brain distribution and severity of NFT and DN in iCJD and control cases of sCJD and AD. (DOCX 49 kb)

Table S1. Molecular classification of sCJD subtypes [8, 15]. Table S2 showing sex, sCJD subtype, age at onset and death, disease duration in study cases and respective controls. (DOCX 17 kb)

Age, disease duration and incubation period in iCJD and sCJD divided into three groups according to age at death. Table S2. Demographic data and molecular subtypes of 67 sCJD cases from the countries providing iCJD cases used as age-group matched controls in assessing prevalence of Aβ and tau pathologies. Table S3. Demographic and medical data on iCJD and sCJD used as controls. (DOCX 37 kb)

Age, disease duration and incubation period in iCJD and sCJD divided into three groups according to age at death. Table S2. Demographic data and molecular subtypes of 67 sCJD cases from the countries providing iCJD cases used as age-group matched controls in assessing prevalence of Aβ and tau pathologies. Table S3. Demographic and medical data on iCJD and sCJD used as controls. (DOCX 37 kb)

Prevalence of Aβ and tau pathologies in iCJD and sCJD used as controls. Table S5. Aβ diffuse plaque staging in cases of iCJD and sCJD not associated with Aβ CP pathology. Table S6. Brain distribution and severity of NFT and DN in iCJD and control cases of sCJD and AD. (DOCX 49 kb)

The presence of pathology related to the deposition of amyloid-β (Aβ) has been recently reported in iatrogenic Creutzfeldt-Jakob disease (iCJD) acquired from inoculation of growth hormone (GH) extracted from human cadaveric pituitary gland or use of cadaveric dura mater (DM) grafts. To investigate this phenomenon further, a cohort of 27 iCJD cases – 21 with adequate number of histopathological sections – originating from Australia, France, Italy, and the Unites States, were examined by immunohistochemistry, amyloid staining, and Western blot analysis of the scrapie prion protein (PrPSc), and compared with age-group matched cases of sporadic CJD (sCJD), Alzheimer disease (AD) or free of neurodegenerative diseases (non-ND). Cases of iCJD and sCJD shared similar profiles of proteinase K-resistant PrPSc with the exception of iCJD harboring the “MMi” phenotype. Cerebral amyloid angiopathy (CAA), either associated with, or free of, Thioflavin S-positive amyloid core plaques (CP), was observed in 52% of 21 cases of iCJD, which comprised 37.5% and 61.5% of the cases of GH- and DM-iCJD, respectively. If only cases younger than 54 years were considered, Aβ pathology affected 41%, 2% and 0% of iCJD, sCJD and non-ND, respectively. Despite the patients’ younger age CAA was more severe in iCJD than sCJD, while Aβ diffuse plaques, in absence of Aβ CP, populated one third of sCJD. Aβ pathology was by far most severe in AD. Tau pathology was scanty in iCJD and sCJD. In conclusion, (i) despite the divergences in the use of cadaveric GH and DM products, our cases combined with previous studies showed remarkably similar iCJD and Aβ phenotypes indicating that the occurrence of Aβ pathology in iCJD is a widespread phenomenon, (ii) CAA emerges as the hallmark of the Aβ phenotype in iCJD since it is observed in nearly 90% of all iCJD with Aβ pathology reported to date including ours, and it is shared by GH- and DM-iCJD, (iii) although the contributions to Aβ pathology of other factors, including GH deficiency, cannot be discounted, our findings increase the mounting evidence that this pathology is acquired by a mechanism resembling that of prion diseases. Electronic supplementary material The online version of this article (10.1186/s40478-017-0503-z) contains supplementary material, which is available to authorized users.