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Serum amyloid A1

About: Serum amyloid A1 is a research topic. Over the lifetime, 111 publications have been published within this topic receiving 3623 citations. The topic is also known as: PIG4 & SAA.


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Journal ArticleDOI
TL;DR: Although the precise role of A-SAA in host defense during inflammation has not been defined, many potential clinically important functions have been proposed for individual SAA family members, including involvement in lipid metabolism/transport, induction of extracellular-matrix-degrading enzymes, and chemotactic recruitment of inflammatory cells to sites of inflammation.
Abstract: The serum amyloid A (SAA) family comprises a number of differentially expressed apolipoproteins, acute-phase SAAs (A-SAAs) and constitutive SAAs (C-SAAs). A-SAAs are major acute-phase reactants, the in vivo concentrations of which increase by as much as 1000-fold during inflammation. A-SAA mRNAs or proteins have been identified in all vertebrates investigated to date and are highly conserved. In contrast, C-SAAs are induced minimally, if at all, during the acute-phase response and have only been found in human and mouse. Although the liver is the primary site of synthesis of both A-SAA and C-SAA, extrahepatic production has been reported for most family members in most of the mammalian species studied. In vitro, the dramatic induction of A-SAA mRNA in response to pro-inflammatory stimuli is due largely to the synergistic effects of cytokine signaling pathways, principally those of the interleukin-1 and interleukin-6 type cytokines. This induction can be enhanced by glucocorticoids. Studies of the A-SAA promoters in several mammalian species have identified a range of transcription factors that are variously involved in defining both cytokine responsiveness and cell specificity. These include NF-κB, C/EBP, YY1, AP-2, SAF and Sp1. A-SAA is also post-transcriptionally regulated. Although the precise role of A-SAA in host defense during inflammation has not been defined, many potential clinically important functions have been proposed for individual SAA family members. These include involvement in lipid metabolism/transport, induction of extracellular-matrix-degrading enzymes, and chemotactic recruitment of inflammatory cells to sites of inflammation. A-SAA is potentially involved in the pathogenesis of several chronic inflammatory diseases: it is the precursor of the amyloid A protein deposited in amyloid A amyloidosis, and it has also been implicated in the pathogenesis of atheroscelerosis and rheumatoid arthritis.

1,038 citations

Journal ArticleDOI
TL;DR: Daily colchicine is the mainstay of the therapy for the disease, resulting in complete remission or marked reduction in the frequency and duration of attacks in most patients, and is also effective in preventing and arresting renal amyloidosis.
Abstract: Familial Mediterranean fever (FMF) is the most frequent hereditary inflammatory disease characterized by self-limited recurrent attacks of fever and serositis. It is transmitted in an autosomal recessive pattern and affects certain ethnic groups mainly Jews, Turks, Arabs, and Armenians. FMF is caused by mutations in MEFV gene, which encodes pyrin. This protein is expressed mainly in myeloid/monocytic cells and modulates IL-1β processing, NF-κB activation, and apoptosis. A mutated pyrin probably results in uncontrolled inflammation. The most devastating complication of FMF is amyloidosis, leading to chronic renal failure. M694V homozygocity, male gender and the α/α genotype of serum amyloid A1 gene are the currently established risk factors for development of amyloidosis. Daily colchicine is the mainstay of the therapy for the disease, resulting in complete remission or marked reduction in the frequency and duration of attacks in most patients. It is also effective in preventing and arresting renal amyloidosis.

278 citations

Journal ArticleDOI
06 Mar 2019-Nature
TL;DR: It is shown that hepatocytes coordinate myeloid cell accumulation and fibrosis within the liver and, in doing so, increase the susceptibility of the liver to metastatic seeding and outgrowth.
Abstract: The liver is the most common site of metastatic disease1. Although this metastatic tropism may reflect the mechanical trapping of circulating tumour cells, liver metastasis is also dependent, at least in part, on the formation of a 'pro-metastatic' niche that supports the spread of tumour cells to the liver2,3. The mechanisms that direct the formation of this niche are poorly understood. Here we show that hepatocytes coordinate myeloid cell accumulation and fibrosis within the liver and, in doing so, increase the susceptibility of the liver to metastatic seeding and outgrowth. During early pancreatic tumorigenesis in mice, hepatocytes show activation of signal transducer and activator of transcription 3 (STAT3) signalling and increased production of serum amyloid A1 and A2 (referred to collectively as SAA). Overexpression of SAA by hepatocytes also occurs in patients with pancreatic and colorectal cancers that have metastasized to the liver, and many patients with locally advanced and metastatic disease show increases in circulating SAA. Activation of STAT3 in hepatocytes and the subsequent production of SAA depend on the release of interleukin 6 (IL-6) into the circulation by non-malignant cells. Genetic ablation or blockade of components of IL-6-STAT3-SAA signalling prevents the establishment of a pro-metastatic niche and inhibits liver metastasis. Our data identify an intercellular network underpinned by hepatocytes that forms the basis of a pro-metastatic niche in the liver, and identify new therapeutic targets.

219 citations

Journal ArticleDOI
TL;DR: A broad overview of the many ways that SAA could contribute to tumour development, and accelerate tumour progression and metastasis is provided to gain a better understanding of this acute-phase reactant as a possible link between chronic inflammation and neoplasia.
Abstract: The synthesis of acute-phase protein serum amyloid A (SAA) is largely regulated by inflammation- associated cytokines and a high concentration of circulating SAA may represent an ideal marker for acute and chronic inflammatory diseases. However, SAA is also synthesized in extrahepatic tissues, e.g. human carcinoma metastases and cancer cell lines. An increasing body of in vitro data supports the concept of involvement of SAA in carcinogenesis and neoplastic diseases. Accumulating evidence suggests that SAA might be included in a group of biomarkers to detect a pattern of physiological events that reflect the growth of malignancy and host response. This review is meant to provide a broad overview of the many ways that SAA could contribute to tumour development, and accelerate tumour progression and metastasis, and to gain a better understanding of this acute-phase reactant as a possible link between chronic inflammation and neoplasia.

193 citations

Journal ArticleDOI
TL;DR: Computer-generated surface profiles show slight differences in accessibility, hydrophilicity and flexibility between the proteins, which may help to explain why SAA2 is found in amyloid fibrils whereas SAA1 is not.
Abstract: C.d. studies have shown that mouse SAA2 (serum amyloid A2) protein has about one-half of the alpha-helix content of the SAA1 (serum amyloid A1) analogue (15 as against 32%), although secondary-structure prediction analyses based on sequence data do not suggest such a large difference between the forms. The decreased helical content may be a reflection or indication of a stronger propensity to aggregation of the SAA2 form compared with SAA1. The main elements of secondary structure in both proteins are beta-sheets/turns. Interactions with Ca2+ are accompanied by small losses in alpha-helix content, whereas binding to chondroitin-6-sulphate in the presence of millimolar Ca2+ also decreases the amount of secondary structure. However, SAA2 binding to heparan sulphate increases its beta-sheet structure, whereas with SAA1 secondary structure is not apparently altered by its interaction with heparan sulphate. Computer-generated surface profiles show slight differences in accessibility, hydrophilicity and flexibility between the proteins. Understanding these differences may help to explain why SAA2 is found in amyloid fibrils whereas SAA1 is not. In particular, a stronger tendency to aggregation might be the reason why SAA2 is deposited exclusively in these fibrils.

168 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202111
20209
201914
20189
201710
20165