Unraveling a rare cause of spinal stenosis: Coexistent AL and ATTR amyloidosis involving the ligamentum flavum

Background: Amyloidosis is a protein misfolding disorder that leads to the deposition of beta-pleated sheets of a fibrillar derivative of various protein precursors. Identification of the type of precursor protein is integral in treatment decision-making. The presence of two different types of amyloid in the same patient is unusually rare, and there are no previous reports of two different types of amyloid deposition in the ligamentum flavum (LF) in the same patient. Case Description: Here, we describe two patients with spinal stenosis who underwent laminectomies and were found to have AL and ATTR amyloid deposits in the LF. Conclusion: As the spine is becoming recognized as a site for ATTRwt amyloid deposition, patients undergoing spinal decompression surgery may potentially benefit from evaluation for amyloidosis in the LF.

Trans ε-Viniferin Decreases Amyloid Deposits With Greater Efficiency Than Resveratrol in an Alzheimer’s Mouse Model

In a previous study, we showed that viniferin decreased amyloid deposits and reduced neuroinflammation in APPswePS1dE9 transgenic mice between 3 and 6 months of age. In the present study, wild type and APPswePS1dE9 transgenic mice were treated from 7 to 11 or from 3 to 12 months by a weekly intraperitoneal injection of either 20 mg/kg viniferin or resveratrol or their vehicle, the polyethylene glycol 200 (PEG 200). The cognitive status of the mice was evaluated by the Morris water maze test. Then, amyloid burden and neuroinflammation were quantified by western-blot, Enzyme-Linked ImmunoSorbent Assay (ELISA), immunofluorescence, and in vivo micro-Positon Emission Tomography (PET) imaging. Viniferin decreased hippocampal amyloid load and deposits with greater efficiency than resveratrol, and both treatments partially prevented the cognitive decline. Furthermore, a significant decrease in brain uptake of the TSPO PET tracer [18F]DPA-714 was observed with viniferin compared to resveratrol. Expression of GFAP, IBA1, and IL-1β were decreased by viniferin but PEG 200, which was very recently shown to be a neuroinflammatory inducer, masked the neuroprotective power of viniferin.

AA-amyloidosis in captive northern tree shrews (Tupaia belangeri)

A high prevalence of AA-amyloidosis was identified in a breeding colony of northern tree shrews ( Tupaia belangeri) in a retrospective analysis, with amyloid deposits in different organs being found in 26/36 individuals (72%). Amyloid deposits, confirmed by Congo red staining, were detected in kidneys, intestines, skin, and lymph nodes, characteristic of systemic amyloidosis. Immunohistochemically, the deposited amyloid was intensely positive with anti-AA-antibody (clone mc4), suggesting AA-amyloidosis. The kidneys were predominantly affected (80%), where amyloid deposits ranged from mild to severe and was predominantly located in the renal medulla. In addition, many kidneys contained numerous cysts with atrophy of the renal parenchyma. There was no significant association between concurrent neoplastic or inflammatory processes and amyloidosis. The lack of distinctive predisposing factors suggests a general susceptibility of captive T. belangeri to develop amyloidosis. Clinical and laboratory findings of a female individual with pronounced kidney alterations were indicative of renal failure. The observed tissue tropism with pronounced kidney alterations, corresponding renal dysfunction, and an overall high prevalence suggests amyloidosis as an important disease in captive tree shrews.

Amyloid cast nephropathy: A rare presentation of multiple myeloma–associated light chain amyloidosis

Introduction: Monoclonal immunoglobulins can cause a variety of histologic patterns of kidney injury, depending on the physicochemical properties. Multiple myeloma manifests more often as light-chain nephropathy. On the other hand, light-chain amyloidosis leads to glomerular and vascular amyloid deposits, but a less common presentation with amyloid casts has also been described. Rarely, more than one histologic pattern can be present in the same patient. Case report: We report a case of a 73-year-old man, diagnosed with multiple myeloma that 8 months after achieving partial response to chemotherapy develops acute kidney injury and nephrotic syndrome. Kidney biopsy revealed features of light-chain nephropathy, amyloid cast nephropathy, and glomerular and vascular amyloid deposits. Immunofluorescence was positive for IgA (++) and lambda chains (+++) and negative for kappa chains. After the diagnosis of multiple myeloma-associated light-chain amyloidosis, chemotherapy was initiated; unfortunately, the patient died 1 month after the diagnosis. Conclusion: Amyloid casts, isolated or accompanied by other renal or extra-renal amyloid deposits, are another form of tubular toxicity caused by dysproteinemias and should be systematically screened in kidney biopsies.

An Observational, Non-Interventional Study for the Follow-up of Patients with Amyloidosis Who Received Miridesap Followed by Dezamizumab in a Phase 1 Study

Background: Miridesap depletes circulating serum amyloid P (SAP) and dezamizumab (anti-SAP monoclonal antibody) targets SAP on amyloid deposits, triggering amyloid removal. In a Phase 1, first-in-human study (FIHS), progressive amyloid removal was observed in some patients after ≤3 cycles of miridesap/dezamizumab.Methods: This observational, non-interventional study in patients who received miridesap/dezamizumab during the FIHS (planned follow-up: 5 years) evaluated response to treatment based on routine assessments of disease status and key organ function. In a post hoc analysis, patients responding to treatment in the FIHS during follow-up were identified as responders and further categorized as sustained or declining responders.Results: In the FIHS, 17/23 patients were treatment responders. Of these patients, seven (immunoglobulin light chain [AL], n=6; serum amyloid A, n=1) were considered sustained responders and ten (fibrinogen-a alpha chain [AFib], n=5; AL, n=4; apolipoprotein A-I, n=1) were considered declining responders. We primarily present responder patient-level data for functional, cardiac, laboratory and imaging assessments conducted during the follow-up period, with non-responder data presented as supplementary.Conclusion: No further development of miridesap/dezamizumab is planned in amyloidosis. However, long-term follow-up of these patients may provide insight into whether active removal of amyloid deposits has an impact on disease progression. Trial registration: ClinicalTrials.gov, NCT01777243. Registered 28 January 2013, https://clinicaltrials.gov/ct2/show/study/NCT01777243.

Evaluation of renal biopsies in various kidney diseases with reference to staining

Renal diseases of different origin and nature may produce essentially similar disturbances of renal functions and may have clinical similarities and hence there was a need to classify renal diseases more scientifically. The basic approach was to correlate clinical signs and symptoms with histological changes in the tissue, using both simple and special staining techniques so as to reach to a definitive diagnosis.The present study was conducted on renal biopsy referred to pathology department. Criteria for successful biopsy were as follows-Adequate biopsy sample size, correct processing of specimen, informed interpretation and issue of an accurate report. A total of 29 renal biopsies were examined. In minimal change disease, only in 4 patients the glomerulus was sclerosed. Membranous glomerulonephritis comprised of the maximum number of cases (9/30). Total of 3 cases of renal biopsies revealed amyloidosis. Focal amyloid deposits with deposits either near the hilum or perivascular areas were found in 33.3% of cases, while extensive amyloid deposits were found in 33.3% of the cases.It is necessary to determine both the type of renal disease and the cause of the primary disorder in order to make the diagnosis and various staining techniques play a very helpful role. The likelihood that the biopsy specimen accurately reflects the type and severity of the underlying disease is directly related to both the diffuseness of the disease process and the amount of tissue examined.

Machine learning quantification of amyloid deposits in histological images of ligamentum flavum

ABSTRACTBackgroundWild-type transthyretin amyloidosis (ATTRwt) is an underdiagnosed and potentially fatal disease. Interestingly, ATTRwt deposits have been found to deposit in the ligamentum flavum (LF) of patients with lumbar spinal stenosis prior to the development of systemic and cardiac amyloidosis. In order to study this phenomenon and its possible relationship with LF thickening and systemic amyloidosis, a precise method of quantifying amyloid deposits in histological slides of LF is critical. However, such a method is currently unavailable. Here, we present a machine learning quantification method with Trainable Weka Segmentation (TWS) to assess amyloid deposition in histological slides of LF.MethodsImages of ligamentum flavum specimens stained with Congo red are obtained from spinal stenosis patients undergoing laminectomies and confirmed to be positive for ATTRwt. Amyloid deposits in these specimens are classified and quantified by TWS through training the algorithm via user-directed annotations on images of LF. TWS can also be automated through exposure to a set of training images with user-directed annotations, and then application to a set of new images without additional annotations. Additional methods of color thresholding and manual segmentation are also used on these images for comparison to TWS.ResultsWe develop the use of TWS in images of LF and demonstrate its potential for automated quantification. TWS is strongly correlated with manual segmentation in the training set of images with user-directed annotations (R = 0.98; p = 0.0033) as well as in the application set of images where TWS was automated (R = 0.94; p = 0.016). Color thresholding was weakly correlated with manual segmentation in the training set of images (R = 0.78; p = 0.12) and in the application set of images (R = 0.65; p = 0.23).ConclusionTWS machine learning closely correlates with the gold standard comparator of manual segmentation and outperforms the color thresholding method. This novel machine learning method to quantify amyloid deposition in histological slides of ligamentum flavum is a precise, objective, accessible, high throughput, and powerful tool that will hopefully pave the way towards future research and clinical applications.

Plasmin activity promotes amyloid deposition in a transgenic model of human transthyretin amyloidosis

Cardiac ATTR amyloidosis, a serious but much under-diagnosed form of cardiomyopathy, is caused by deposition of amyloid fibrils derived from the plasma protein transthyretin (TTR), but its pathogenesis is poorly understood and informative in vivo models have proved elusive. Here we report the generation of a mouse model of cardiac ATTR amyloidosis with transgenic expression of human TTRS52P. The model is characterised by substantial ATTR amyloid deposits in the heart and tongue. The amyloid fibrils contain both full-length human TTR protomers and the residue 49-127 cleavage fragment which are present in ATTR amyloidosis patients. Urokinase-type plasminogen activator (uPA) and plasmin are abundant within the cardiac and lingual amyloid deposits, which contain marked serine protease activity; knockout of α2-antiplasmin, the physiological inhibitor of plasmin, enhances amyloid formation. Together, these findings indicate that cardiac ATTR amyloid deposition involves local uPA-mediated generation of plasmin and cleavage of TTR, consistent with the previously described mechano-enzymatic hypothesis for cardiac ATTR amyloid formation. This experimental model of ATTR cardiomyopathy has potential to allow further investigations of the factors that influence human ATTR amyloid deposition and the development of new treatments.