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Animal Models Of Connective Tissue Diseases
Published in Marcos Rojkind, Connective Tissue in Health and Disease, 2017
Gerald Α. Hegreberg, Lynetta J. Freeman
Amyloidosis is a condition in which amyloid, an abnormal protein with a characteristic beta-pleated conformation, is deposited extracellularly in tissues of the body.230-232 The major forms of amyloid are termed primary and secondary amyloid, depending on the source. Amyloid is composed of both major and minor proteins, and the major protein forms the fibril component of the amyloid.184,230,231 in primary amyloidosis, the major protein is derived from the light chain of the immunoglobulin molecule and is called amyloid light chain (AL). Primary amyloidosis either occurs in the absence of a recognizable disease process or is associated with multiple myeloma. The major protein in secondary amyloidosis is not related to immunoglobulin but is derived from the protein component of high-density lipoprotein from serum. This major protein is termed amyloid A (AA), and because it is derived from serum, it is also termed serum amyloid A (SAA). SAA is an acute phase protein which is produced in inflammatory diseases. Secondary amyloidosis is found coexistent with, or as a result of, a variety of conditions including chronic infections, neoplasia, and heritable diseases in which the deposition of amyloid is a major disease component. A serum-derived minor protein component, termed serum amyloid Ρ (SAP), has a structure similar to C-reactive protein and is always found in amyloid deposits.184
Case 80: Renal Failure in an Intravenous Drug User
Published in Layne Kerry, Janice Rymer, 100 Diagnostic Dilemmas in Clinical Medicine, 2017
Secondary AA amyloidosis is associated with chronic inflammatory conditions, such as rheumatoid arthritis or systemic lupus erythematosus, but is becoming more frequently identified in the intravenous drug using population who often experience recurrent viral and bacterial infections. People who ‘skin-pop’ in particular are at risk of chronic cutaneous infections. Serum amyloid A protein is an acute phase protein and thus levels rise in the presence of inflammation. Deposition of amyloid A fibrils within the kidneys can lead to renal amyloidosis, presenting with proteinuria and progressing to renal failure.
An EM Autoradiography and Immunofluorescence Study Examining the Pathway of Serum Amyloid a Through the Macrophage
Published in Gilles Grateau, Robert A. Kyle, Martha Skinner, Amyloid and Amyloidosis, 2004
Serum amyloid A (SAA) is an evolutionarily conserved acute phase protein whose plasma concentration increases 1000-fold during inflammation (1,2). The major biological function of AP-SAA still remains to be elucidated though there is growing evidence that SAA is involved in cholesterol transport (3). In this study we investigated the pathway that HDL/SAA followed through murine peritoneal macrophages to elucidate a putative role for SAA during inflammation. Using both immunofluorescence and EM autoradiography we showed that HLD/SAA was taken up rapidly by macrophages, proceeded through the cytoplasm to the peri-nuclear region, was then observed in the nucleus, later re-emerged to the cytoplasm and the plasma membrane where it was exocytosed into the extracellular environment. Through both of these techniques we were able to demonstrated that SAA has a finite association with macrophages that last approximately 1 hour, which is consistent with the half-life of SAA in the circulation. The observation that SAA is in the nucleus is to the best of our knowledge a novel finding and has implications that SAA may play a role in gene regulation.
An expert overview of pulmonary fibrosis in sarcoidosis
Published in Expert Review of Respiratory Medicine, 2023
Rohit Gupta, Jin Sun Kim, Robert P Baughman
A critical risk factor for development of fibrosis is non-resolving inflammation [24]. Although the pathophysiology of fibrosis is not clearly understood, studies have found associations between fibrosis development and changes in transforming growth factor-B, macrophage switching, and Th1 to Th2 transition [25,26]. As regulatory T-cells are activated, acute phase proteins like serum amyloid A are secreted, triggering a cascade of pro-inflammatory cytokines to amplify inflammation [27–29]. On histopathology, fibrotic changes seen in end-stage pulmonary sarcoidosis are distinct from that of usual interstitial pneumonia seen in idiopathic pulmonary fibrosis [30–33]. Patients with fibrotic sarcoidosis have lymphangitic distribution of fibrosis, rare foci of fibroblasts or architectural distortion, and the presence of granulomatous inflammation. Explanted lungs from patients with advanced pulmonary sarcoidosis undergoing transplantation similarly found fibrosis along a central and peribronchovascular distribution, granulomatous involvement in all compartments (parenchyma, vasculature, pleura, and lymph nodes) suggesting widespread but variable involvement of granulomatous inflammation and fibrosis in end-stage pulmonary sarcoidosis (Figure 2) [34]. Some patients can have a usual interstitial pneumonitis pattern with fibroblastic foci [30,32]. This subgroup of progressive fibrosis in sarcoidosis needs further study.
Comparison of the ELISA method with the nephelometric method for determination of serum amyloid A in patients with COVID 19
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2023
Boris Jegorović, Neda Milinković, Marija Sarić Matutinović, Sandra Šipetić Grujičić, Svetlana Ignjatović
This method comparison study included 80 serum samples tested in parallel by two methods analyzed. Serum samples were obtained from the patients with the COVID-19, examined in the outpatient setting of the Clinic for Infectious and Tropical Diseases of the University Clinical Center of Serbia. Study included 34 female and 46 male patients. The average age of patients (95% Confidence Interval for mean, CI) was 56.1 (51.6–60.7) years. The average duration of infection was 6.3 (5.5–7.2) days. Serum samples were collected strictly following standard venipuncture procedures [9]. Becton & Dickinson closed venipuncture systems (reusable adapter, 22 standard wire gauge diameter needles, and serum separator tube disposable gel vacutainers) were used for blood collection. After aliquoting, the samples were stored at −20 °C until analysis. We have determined serum amyloid A levels from each specimen in duplicate by the nephelometry and comparative method. Specimens were selected to cover the entire working range and represented the spectrum of values expected in routine use. This research was approved by the decision of the Ethics Commission of the Medical Faculty of the University of Belgrade under number 1322/II-1,2 from 24 February 2022.
Sarcoidosis-associated renal AA amyloidosis and crescentic necrotizing glomerulonephritis
Published in Baylor University Medical Center Proceedings, 2022
Albert Bui, Cherise Cortese, Nabeel Aslam
In summary, our patient presented with AKI due to biopsy-proven AA amyloidosis and CNG. Sarcoidosis was strongly suspected to be the impetus, as evidenced by enlargement of necrotizing and nonnecrotizing granulomatous lesions in the liver and spleen, lymphadenopathy, inflammatory lesions in osseous structures, pleural effusions, and elevated angiotensin-converting enzyme and alkaline phosphatase level.1,2,8–12 AA amyloidosis is derived from serum amyloid A protein, an acute phase reactant generated from various inflammatory conditions.13 We specifically identified AA amyloid via proteomic methods with robust diagnostic value.14 AA amyloidosis presenting with CNG is rare, reported primarily in rheumatoid arthritis, vasculitis, and malignancies.15–18 This case is the first to report coexisting entities in sarcoidosis.