Search

Amyloid A (AA) amyloidosis is experimentally transmissible in some animal species, such as mice and chickens. While the spleen is important as the initial deposition site in the transmission of AA amyloidosis, it is not essential for establishing the transmission, and its role is not precisely understood. In this study, to clarify why the spleen is the first site of deposition in transmissible AA amyloidosis, we administered amyloid enhancing factor, which is AA fibrils extracted from AA amyloidosis affected mouse to local organs (liver, spleen, kidney, stomach wall, and Peyer's patches), to tail vain and into peritoneum; then compared the amyloid distribution. Interestingly, initial amyloid deposition was observed at the administration site in each administered organ, not just the spleen. Furthermore, the amount of amyloid deposition in intra-organ administration groups was larger than that of the intravenous or intraperitoneal administration groups. This study indicates that locally exposed AEF initiates in situ amyloid deposition, from which amyloid deposition spreads throughout the body.

Keratinic primary localized cutaneous amyloidosis is a disease in humans; however, no similar condition has been reported in animals. This study aimed to investigate cutaneous keratinic amyloid deposition in dogs and elucidate its etiology. Canine hair follicle tumor tissues were histopathologically analyzed. Immunohistochemistry and mass spectrometry–based proteomic analyses were performed to identify precursor protein candidates. Structural prediction and in vitro fibrillization analyses were conducted to determine the amyloidogenic region and gene sequencing analysis was performed to assess mutations. Of the 266 samples, 16 had amyloid deposition. Amyloid deposits were found in the stroma of tumors and in the margins of keratin debris and around normal hair follicles. Cytokeratin 5 (CK5) was identified as a precursor protein candidate. C-terminal truncation of CK5 was observed in amyloid deposits, and the truncation sites varied depending on the deposition pattern. There was a significantly higher incidence of amyloid deposition in Shiba dogs, and CK5 amino acid polymorphisms were identified in these dogs. A part of the C-terminal region of both canine and human CK5 exhibited highly amyloidogenic properties in vitro. This study revealed the existence of cutaneous keratinic amyloid deposition in animals and identified CK5 as an amyloid precursor protein, providing novel insights into understanding the etiology of cutaneous amyloidosis.

Amyloid A (AA) amyloidosis is a lethal disease characterized by systemic AA amyloid deposition, and is reported in many animal species. Despite experiments have shown that AA amyloidosis can be transmitted orally, horizontal transmission and cross-species transmission are concerns, the transmission mechanism has been unknown. In this study, we examined the oral transmission efficiency of AA amyloidosis using oxazolone-induced gastrointestinal disorder mice. As a result, the upper or lower gastrointestinal disorder groups developed more severe amyloid deposition in systemic tissues than the group without gastrointestinal disorders. The results of this study suggest that gastrointestinal damage promotes the oral transmission of AA amyloidosis.

Amyloidosis is diagnosed by the histologic detection of amyloid deposits; however, this method has limitations such as a prolonged diagnosis time and the need for histologic proficiency. We aimed to develop a rapid and simple method for diagnosing amyloidosis by targeting amyloid-specific endogenous fluorescence, which has not been reported previously, to our knowledge. Fluorescence fingerprint analysis of amyloid extracts and tissue homogenates derived from amyloid A (AA) amyloidosis-affected cattle exhibited a specific intrinsic fluorescence pattern. Furthermore, principal component analysis using analytical data revealed that AA could be identified by peaks near λex 350 nm and λem 430 nm. Fluorescence spectrometry analysis using tissue homogenates, which does not require special histochemical staining, enables the rapid detection of bovine AA.

In AA amyloidosis, cross-species oral transmission has been demonstrated in several animal models. While it is known that the transmission efficiency of AA amyloidosis between different species is lower than that among the same species, the mechanism of this species-barrier is unclear. In this study, we found at first that mice orally given a large amount of bovine AA simultaneously with inflammatory stimulation did not develop AA amyloidosis. Therefore, we hypothesized that the low efficiency of the cross-species oral transmission of AA amyloidosis might be due to the low absorption rate in Peyer’s patches. To evaluate the hypothesis, we next investigated whether bovine AA was taken up by Peyer’s patches and translocated to other organs in vivo and ex vivo models. The direct absorption of bovine AA by Peyer’s patches was not observed. Besides, translocation of bovine AA to the mesenteric lymph nodes, spleen, liver, or kidney was not observed except the mesenteric lymph node of a single mouse. Thus, absorption of bovine AA by Peyer’s patches occurred much less efficiently in mouse models of cross-species oral transmission of AA amyloidosis. The present study suggests that the less efficient amyloid uptake by Peyer’s patches may be involved in the species-barrier of oral transmission of AA amyloidosis.

The brain of a chimpanzee estimated to be 68 years old, the oldest reported so far, has been examined. Pathological analyses revealed the formation of mild tau-positive neuritic clusters and cytoplasmic α-synuclein aggregates, in addition to severe cerebral amyloid angiopathy and diffuse plaques, but no tangle lesions were observed.

In animals, most cases of systemic amyloidosis are of amyloid A type, and the other types of systemic amyloidoses are rare. This study analyzed systemic amyloidosis in a 15-year-old female Tsushima leopard cat. Amyloid deposits strongly positive for Congo red staining were observed in the arterial walls as well as the interstitium in multiple organs. Mass spectrometry–based proteomic analysis with laser microdissection of amyloid deposits identified epidermal growth factor–containing fibulin-like extracellular matrix protein 1 (EFEMP1) as a prime amyloidogenic protein candidate. Immunohistochemistry showed that the amyloid deposits were positive for the N-terminal region of EFEMP1. From these results, the present case was diagnosed as EFEMP1-derived amyloidosis. It is the first such case in an animal. EFEMP1-derived amyloidosis in humans has recently been reported as a systemic amyloidosis, and it is known as an age-related venous amyloidosis. The present case showed different characteristics from human EFEMP1-derived amyloidosis, including the amyloid deposition sites and the amyloidogenic region of the EFEMP1 protein, suggesting a different pathogenesis between Tsushima leopard cat and human EFEMP1-derived amyloidosis.

Amyloidosis is classified according to the amyloid precursor protein, and accurate diagnosis of the amyloidosis type may guide appropriate treatment. Immunohistochemistry and Congo red staining are the most frequently used methods used to distinguish types of amyloidosis, but problems with specificity and sensitivity indicate the need for an alternative diagnostic method. In this study, we evaluated laser microdissection-liquid chromatography-tandem mass spectrometry (LMD-LC-MS/MS) for the diagnosis of amyloid light-chain (AL) amyloidosis in animals. Plasmacytomas with amyloid deposits from 15 dogs and 2 cats were subjected to Congo red staining with or without potassium permanganate pretreatment, immunohistochemistry for kappa and lambda light chains, and LMD-LC-MS/MS. Congo red staining was diagnostic in 12 of 17 cases based on resistance to potassium permanganate pretreatment, but in 5 of 17 cases the pretreatment unexpectedly reduced Congo red staining or abrogated the birefringence and a definitive diagnosis could not be reached. Immunohistochemistry detected kappa or lambda light chains in 6 of 17 cases. With LMD-LC-MS/MS, immunoglobulin lambda light chain was detected in all 17 cases. The amyloid signature proteins ApoA-I, ApoA-IV, and ApoE were detected in 9, 1, and 3 of the 15 canine cases by LMD-LC-MS/MS, but not in the feline cases. In conclusion, LMD-LC-MS/MS consistently determined the amyloid type in all examined specimens, while Congo red staining after potassium permanganate treatment and immunohistochemistry were less sensitive tests.