Proteomic analysis shows that the main constituent of subepidermal localised cutaneous amyloidosis is not galectin-7

Identification of uromodulin deposition in the stroma of perinephric fibromyxoid nephrogenic adenoma by mass spectrometry

Nephrogenic adenoma (NA) is an epithelial lesion that usually occurs in the mucosa of the urinary tract. Rare cases of deep infiltrative or perinephric lesions have also been reported. Recently, NA with characteristic fibromyxoid stroma (fibromyxoid NA) has been proposed as a distinct variant. Although shedding of distal renal tubular cells due to urinary tract rupture has been postulated as the cause of NA in general, the mechanism underlying extraurinary presentation of NA and fibromyxoid stromal change in fibromyxoid NA remains unknown. In this study, we performed mass spectrometry (MS) analysis in a case of perinephric fibromyxoid NA of an 82-year-old man who underwent right nephroureterectomy for distal ureteral cancer. The patient had no prior history of urinary tract injury or radiation. Periodic acid-Schiff staining-positive eosinophilic structureless deposits in the stroma of fibromyxoid NA were microdissected and subjected to liquid chromatography/MS. The analysis revealed the presence of a substantial amount of uromodulin (Tamm-Horsfall protein). The presence of urinary content in the stroma of perinephric fibromyxoid NA suggests that urinary tract rupture and engraftment of renal tubular epithelial cells directly cause the lesion.

Characterization of Epidermal Function in Individuals with Primary Cutaneous Amyloidosis

Purpose

To compare epidermal biophysical properties, indicators of epidermal function, in individuals with and without primary cutaneous amyloidosis (PCA).

Patients and Methods

This study incorporated 189 patients with PCA and 166 healthy individuals. The GPSkin Barrier was employed to measure transepidermal water loss (TEWL) rates and hydration levels of the stratum corneum. The Sebumeter and the Skin pH Meter were utilized to determine the skin surface's sebum content and pH, respectively. The severity of pruritus in participants was evaluated using the visual analog scale (VAS).

Results

Compared to the control group without PCA, individuals with PCA displayed a notable increase in skin surface pH and TEWL and a decrease in the hydration levels of the stratum corneum (p<0.0001 for all parameters). Additionally, the sebum content was markedly lower in those with PCA than in the controls (p<0.0001). Of particular note, both TEWL and skin surface pH at the lesion sites on the back and the shin were more elevated in lichenoid amyloidosis (LA) and in macular amyloidosis (MA), whereas hydration levels of the stratum corneum and sebum levels were diminished in LA compared to MA (p<0.05). In conclusion, both hydration levels of the stratum corneum and sebum content exhibited an inverse relationship with pruritus severity, whereas TEWL and skin surface pH demonstrated a positive correlation with pruritus intensity.

Conclusion

The function of the epidermis is compromised in individuals diagnosed with PCA. However, the mechanisms underlying these changes await further investigation.

Barrier function and ultrastructure characteristics of epidermis in patients with primary cutaneous amyloidosis

Previous studies on primary cutaneous amyloidosis (PCA) have mainly focused on exploring genetic mutation and components of amyloid in patients with PCA. However, studies on skin barrier function in PCA patients are scarce. Here, we detected the skin barrier function in PCA patients and healthy people by using noninvasive techniques and characterized ultrastructural features of PCA lesions compared with healthy people using transmission electron microscopy (TEM). The expression of proteins related to skin barrier function was examined by immunohistochemistry staining. A total of 191 patients with clinically diagnosed PCA and 168 healthy individuals were enrolled in the study. Our analysis revealed that all investigated lesion areas displayed higher transepidermal water loss and pH values, and lower Sebum levels and stratum corneum hydration levels in PCA patients compared with the same site area in healthy individuals. The TEM results showed that the intercellular spaces between the basal cells were enlarged and the number of hemidesmosomes decreased in PCA lesions. Immunohistochemical staining showed that the expression of integrin α6 and E-cadherin in PCA patients was less than that in healthy controls, while no differences in the expression of loricrin and filaggrin were observed. Our study revealed that individuals with PCA displayed skin barrier dysfunction, which may be related to alterations in epidermal ultrastructure and a decrease in the skin barrier-related protein E-cadherin. However, the molecular mechanisms underlying skin barrier dysfunction in PCA remain to be elucidated.

Keratinic amyloid deposition in canine hair follicle tumors

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.

Clinical Amyloid Typing by Proteomics: Performance Evaluation and Data Sharing Between Two Centres

Amyloidosis is a relatively rare human disease caused by the deposition of abnormal protein fibres in the extracellular space of various tissues, impairing their normal function. Proteomic analysis of patients’ biopsies, developed by Dogan and colleagues at the Mayo Clinic, has become crucial for clinical diagnosis and for identifying the amyloid type. Currently, the proteomic approach is routinely used at National Amyloidosis Centre (NAC, London, UK) and Istituto di Tecnologie Biomediche-Consiglio Nazionale delle Ricerche (ITB-CNR, Milan, Italy). Both centres are members of the European Proteomics Amyloid Network (EPAN), which was established with the aim of sharing and discussing best practice in the application of amyloid proteomics. One of the EPAN’s activities was to evaluate the quality and the confidence of the results achieved using different software and algorithms for protein identification. In this paper, we report the comparison of proteomics results obtained by sharing NAC proteomics data with the ITB-CNR centre. Mass spectrometric raw data were analysed using different software platforms including Mascot, Scaffold, Proteome Discoverer, Sequest and bespoke algorithms developed for an accurate and immediate amyloid protein identification. Our study showed a high concordance of the obtained results, suggesting a good accuracy of the different bioinformatics tools used in the respective centres. In conclusion, inter-centre data exchange is a worthwhile approach for testing and validating the performance of software platforms and the accuracy of results, and is particularly important where the proteomics data contribute to a clinical diagnosis.

Amyloid nomenclature 2020: update and recommendations by the International Society of Amyloidosis (ISA) nomenclature committee

The ISA Nomenclature Committee met electronically before and directly after the XVII ISA International Symposium on Amyloidosis, which, unfortunately, had to be virtual in September 2020 due to the ongoing COVID-19 pandemic instead of a planned meeting in Tarragona in March. In addition to confirmation of basic nomenclature, several additional concepts were discussed, which are used in scientific amyloid literature. Among such concepts are cytotoxic oligomers, protofibrils, primary and secondary nucleation, seeding and cross-seeding, amyloid signature proteins, and amyloid plaques. Recommendations for their use are given. Definitions of amyloid and amyloidosis are confirmed. Possible novel human amyloid fibril proteins, appearing as 'classical' in vivo amyloid, were discussed. It was decided to include fibulin-like extracellular matrix protein 1 (amyloid protein: AEFEMP1), which appears as localised amyloid in portal veins. There are several possible amyloid proteins under investigation, and these are included in a new Table.