Expression Of Serum Amyloid A Research Articles

CHRONIC CRITICAL ILLNESS-INDUCED MUSCLE ATROPHY: INSIGHTS FROM A TRAUMA MOUSE MODEL AND POTENTIAL MECHANISM MEDIATED VIA SERUM AMYLOID A.

Background: Chronic critical illness (CCI), which was characterized by persistent inflammation, immunosuppression, and catabolism syndrome (PICS), often leads to muscle atrophy. Serum amyloid A (SAA), a protein upregulated in critical illness myopathy, may play a crucial role in these processes. However, the effects of SAA on muscle atrophy in PICS require further investigation. This study aims to develop a mouse model of PICS combined with bone trauma to investigate the mechanisms underlying muscle weakness, with a focus on SAA. Methods: Mice were used to examine the effects of PICS after bone trauma on immune response, muscle atrophy, and bone healing. The mice were divided into two groups: a bone trauma group and a bone trauma with cecal ligation and puncture group. Tibia fracture surgery was performed on all mice, and PICS was induced through cecal ligation and puncture surgery in the PICS group. Various assessments were conducted, including weight change analysis, cytokine analysis, hematological analysis, grip strength analysis, histochemical staining, and immunofluorescence staining for SAA. In vitro experiments using C2C12 cells (myoblasts) were also conducted to investigate the role of SAA in muscle atrophy. The effects of inhibiting receptor for advanced glycation endproducts (RAGE) or JAK2 on SAA-induced muscle atrophy were examined. Bioinformatic analysis was conducted using a dataset from the GEO database to identify differentially expressed genes and construct a coexpression network. Results: Bioinformatic analysis confirmed that SAA was significantly upregulated in muscle tissue of patients with intensive care unit-induced muscle atrophy. The PICS animal models exhibited significant weight loss, spleen enlargement, elevated levels of proinflammatory cytokines, and altered hematological profiles. Evaluation of muscle atrophy in the animal models demonstrated decreased muscle mass, grip strength loss, decreased diameter of muscle fibers, and significantly increased expression of SAA. In vitro experiment demonstrated that SAA decreased myotube formation, reduced myotube diameter, and increased the expression of muscle atrophy-related genes. Furthermore, SAA expression was associated with activation of the FOXO signaling pathway, and inhibition of RAGE or JAK2/STAT3-FOXO signaling partially reversed SAA-induced muscle atrophy. Conclusions: This study successfully develops a mouse model that mimics PICS in CCI patients with bone trauma. Serum amyloid A plays a crucial role in muscle atrophy through the JAK2/STAT3-FOXO signaling pathway, and targeting RAGE or JAK2 may hold therapeutic potential in mitigating SAA-induced muscle atrophy.

Clinical diagnostic value of IL-14, 1L-16 and SAA in periodontitis.

Periodontitis is a chronic infectious disease, which leads to inflammatory destruction of periodontal supporting tissues. Interleukin 14 (IL-14), Interleukin 16 (IL-16) and serum amyloid A (SAA) have been demonstrated to be abnormally expressed in inflammatory diseases. Therefore, this study was performed to analyzed the expression and potential clinical values of IL-14, 1L-16 and SAA in periodontitis. A total of 100 periodontitis patients and 100 healthy volunteers were recruited and the saliva and serum samples were collected. Then the C-reactive protein (CRP), procalcitonin (PCT), IL-14, 1L-16 and SAA levels in the saliva and serum of periodontitis patients were measured by Elisa kits. Besides, the significance of CRP, PCT, IL-14, 1L-16 and SAA in periodontitis patients were analyzed by receiver operating characteristic (ROC) analysis. The results showed that CRP, PCT, IL-14, 1L-16 and SAA levels were significantly increased in the the saliva and serum of the periodontitis patients. Additionally, the area under the curve (AUC) of saliva CRP, PCT, IL-14, 1L-16 and SAA for the diagnosis of periodontitis were 0.9035, 0.9435, 0.9508, 0.9500 and 0.9467, respectively. The AUC of serum CRP, PCT, IL-14, 1L-16 and SAA for the diagnosis of periodontitis were 0.9035, 0.9435, 0.9508, 0.9500 and 0.9467, respectively. What's more, the diagnostic value of IL-14, 1L-16 and SAA were enhanced when combining with CRP and PCT. This study demonstrated that IL-14, IL-16 and SAA expressions were upregulated in periodontitis patients and exhibited a significant significance for periodontitis diagnosis.

A SNP in the 5’ flanking region of the SAA1 gene is associated with serum levels of serum amyloid A and cardiovascular risk factors

BackgroundElevated serum levels of serum amyloid A (SAA) are associated with increased risk of cardiovascular disease. In this study, we examine associations between allelic variation in the rs11024595 single nucleotide polymorphism (SNP) in the 5’ flanking region of the SAA1 gene and adipose tissue gene expression, serum levels of SAA and cardiovascular risk factors.MethodsDNA samples from 729 participants in the SibPair study, comprising weight discordant siblings and their biological parents, and 3542 participants (1783 patients treated with bariatric surgery and 1759 controls) from the Swedish Obese Subjects (SOS) study were used. The rs11024595 SNP was genotyped in both cohorts using Pyrosequencing or the Sequenom MassARRAY platform, respectively. Blood chemistry and anthropometry were assessed at study start. Adipose tissue SAA1 gene expression and serum levels of SAA in the SibPair study were analyzed with DNA microarray or immunoassay, respectively.ResultsIn the SibPair study, the rs11024595 SNP was associated with serum levels of SAA (P = 0.0050) where T allele carriers displayed lower levels of SAA (P = 0.0025) but no association between genotype and adipose tissue SAA1 gene expression was found. In the SOS study, the rs11024595 SNP was associated with serum levels of HDL cholesterol (P = 0.0045), triglycerides (P = 0.025) and apolipoprotein E (P = 0.026). Moreover, T allele carriers had lower levels of HDL cholesterol (P = 0.0148), but higher levels of triglycerides (P = 0.0418) and apolipoprotein E (P = 0.028) compared to C allele homozygotes. The rs11024595 SNP was also associated with plasma glucose (P = 0.044).ConclusionsThe rs11024595 SNP in the 5’ flanking region of the SAA1 gene is associated with both serum levels of SAA and other cardiovascular risk factors. Future studies are required to elucidate whether the rs11024595 SNP can affect the risk of cardiovascular events.Trial registrationClinicalTrials.gov Identifier: NCT01479452 Registered 24 November 2011 - retrospectively registered.

Aspirin-Triggered Resolvin D1 Reduces Proliferation and the Neutrophil to Lymphocyte Ratio in a Mutant KRAS-Driven Lung Adenocarcinoma Model.

Simple SummaryAspirin-triggered resolvin D1 (AT-RvD1) is biosynthesised by leukocytes as a mechanism to resolve inflammation during infection and/or injury. Emerging studies reveal that AT-RvD1 also has anti-cancer properties associated with stimulating macrophage-mediated clearance of tumour debris. No study to date has investigated how AT-RvD1 influences the neutrophil to lymphocyte ratio (NLR) in lung cancer, an established marker of poor prognosis. The biosynthesis of AT-RvD1 is dependent on the ALOX5 gene, and we reveal that ALOX5 mRNA expression was markedly reduced in lung adenocarcinoma tumours. We next utilised an oncogenic KrasG12D lung adenocarcinoma mouse model to investigate the efficacy of AT-RvD1 in vivo. We show for the first time that AT-RvD1 reduces tumour growth in the lungs of KrasG12D mice and alters the immune landscape in tumours by reducing the NLR.Tumour-associated neutrophils (TANs) can support tumour growth by suppressing cytotoxic lymphocytes. AT-RvD1 is an eicosanoid that can antagonise neutrophil trafficking instigated by ALX/FPR2 ligands such as serum amyloid A (SAA). We aimed to establish whether SAA and ALOX5 expression associates with TANs and investigate the immunomodulatory actions of AT-RvD1 in vivo. MPO-positive neutrophils were quantified in tumour blocks from lung adenocarcinoma (n = 48) and control tissue (n = 20) by IHC. Tumour expression of SAA and ALOX5 were analysed by RTqPCR and an oncogenic KrasG12D lung adenocarcinoma mouse model was used to investigate the in vivo efficacy of AT-RvD1 treatment. ALOX5 expression was markedly reduced in lung adenocarcinoma tumours. The SAA/ALOX5 ratio strongly correlated with TANs and was significantly increased in tumours harbouring an oncogenic KRAS mutation. AT-RvD1 treatment reduced tumour growth in KrasG12D mice, which was accompanied by suppressed cellular proliferation within parenchymal lesions. In addition, AT-RvD1 significantly reduced the neutrophil to lymphocyte ratio (NLR), an established prognostic marker of poor survival in adenocarcinoma. This study identifies a novel molecular signature whereby elevated levels of SAA relative to ALOX5 favour accumulation of TANs. Furthermore, the ALOX5/5-LO enzymatic product, AT-RvD1, markedly reduced the NLR and suppressed tumour growth in KrasG12D mice.

Mycoplasma synoviae induces serum amyloid A upregulation and promotes chicken synovial fibroblast cell proliferation

Mycoplasma synoviae (MS) infection causes infectious synovitis and arthritis with hyperplasia of synovial cells in the chicken joint. However, its mechanism is unknown. We used primary chicken synovial fibroblast (CSF) as the research object to study the role of MS in the proliferation of MS-infected CSF and determine the mechanisms involved. Using integrated transcriptomic and proteomic analyses of the interaction between CSF and MS, we screened a proliferation-regulated factor, serum amyloid A (SAA), that may regulate proliferation of MS-infected CSF. SAA appears to be associated with MS-induced CSF proliferation. To study the role of SAA in MS-induced CSF proliferation, a eukaryotic expression vector overexpressing SAA and a small interfering RNA (siRNA) targeting Saa were constructed to manipulate the expression of SAA. Cell proliferation and apoptosis were detected via cell counting kit-8 (CCK-8), 5-Ethynyl-2′-deoxyuridine (EdU), or terminal deoxyribonucleotidyl transferase-mediated dUTP nick-dnd labeling (TUNEL) assays, respectively. Western blot analysis was used to examine the protein expression level of SAA, cyclin E1, and cyclin-dependent kinase 2 (CDK2). In vitro, MS significantly promoted the proliferation of CSF and increased the production of SAA. Overexpression of SAA accelerated the proliferative ability of CSF, whereas knockdown of SAA depressed the proliferative ability of CSF. A TUNEL assay indicated that MS did not induce apoptosis. Silencing of SAA suppressed the expression of cyclin E1 and CDK2. These results suggest that MS may upregulate the expression of SAA, accelerate the cell cycle, and promote proliferation of CSF.

Evaluation of indirect diagnostic tests and PBMC expression of innate immune genes in subclinical mastitis in dairy cows

The aim of this study was to estimate the prevalence of subclinical mastitis (SCM), its innate immunity and to compare the efficacy of indirect diagnostic tests [California mastitis test (CMT), differential electrical conductivity (DEC), absolute EC, enzyme based color detection method (Tanucheck kit) and brothymol blue strip (BTB) tests] to milk somatic cell count (SCC) method using 200×103 cells/ml as a cut off value in Deoni (N=27) and HF crossbred (N=32) cows. Cumulative prevalence of SCM was 38% and 63% in Deoni and HF crossbred cows, respectively on milk SCC basis (N=215). Breed, udder health status and its interaction had significant effect on SCC level. The overall sensitivity and specificity of above indirect tests were 38 and 99%; 52 and 72%; 52 and 69%; 76 and 31%, and 1 and 100%, respectively. mRNA expression of serum amyloid A (SAA), IL-1β and TNF- α genes were significantly up-regulated while, TNF-α gene was significantly down-regulated in PBMC of SCM affected HF crossbred and Deoni cows, respectively. It is concluded that, DEC is more suitable indirect method to detect SCM and mRNA expression of SAA and TNF-α was strongly related to SCM in HF crossbred and Deoni cows, respectively.

Abstract 12527: Serum Amyloid A, Inflammasome Activation and Stroke

Serum amyloid A (SAA) proteins are critical to the regulation of inflammation in systemic as well as neurological diseases. Studies have shown that during an acute phase response (APR), SAA levels increase 1000-fold and can stimulate the inflammasome, trigger the recruitment of immune cells to inflammatory sites, and elicit the induction of enzymes that degrade extracellular matrix. Our long-term goal is to dissect the mechanisms regulating SAA function, particularly the contribution to stroke related damage. Recent studies have demonstrated that activation of the inflammasome is a critical event in stroke progression in mice. The central hypothesis is that SAA activates the NLRP3 inflammasome, and amplifying the local inflammatory responses that enhance neuronal cell death and stroke progression. We show that activation of the NLRP3 inflammasome by SAA exacerbates stroke in mice. Using mice deficient in SAA, RAGE and various inflammasome components (cathepsin B, NLRP3, ASC, caspase-1 and IL-1beta) or IL-1R mice, we demonstrated that SAA-mediated stroke outcomes are dependent on the NLRP3 inflammasome. In addition, using microglial cell cultures, we determined the impact of SAA on RAGE mediated pathologies (ROS generation, etc.) as well as the influence of SAA-HDL on SAA-mediated NLRP3 activation. We tested the hypothesis that systemic SAA exacerbates the progression of neuronal cell death and inflammation in stroke. We showed that SAA deficient mice determined the impact on stroke infarct volume and outcomes. In addition, using viral vectors to express SAA as well as an inducible transgene help us determine the role of SAA with specific expression of SAA. The impact of SAA on inflammation, neuronal cell death, matrix remodeling, etc. was attenuated in SAA deficient mice. In addition, we demonstrated the role of SAA and the inflammasome in human stroke, and the relationship between plasma SAA, IL-1beta and the impact on stroke outcomes.

Serum amyloid A exhibits pH dependent antibacterial action and contributes to host defense against Staphylococcus aureus cutaneous infection

Serum amyloid A (SAA), one of the major highly conserved acute-phase proteins in most mammals, is predominantly produced by hepatocytes and also by a variety of cells in extrahepatic tissues. It is well-known that the expression of SAA is sharply increased in bacterial infections. However, the exact physiological function of SAA during bacterial infection remains unclear. Herein, we showed that SAA expression significantly increased in abscesses of Staphylococcus aureus cutaneous infected mice, which exert direct antibacterial effects by binding to the bacterial cell surface and disrupting the cell membrane in acidic conditions. Mechanically, SAA disrupts anionic liposomes by spontaneously forming small vesicles or micelles under acidic conditions. Especially, the N-terminal region of SAA is necessary for membrane disruption and bactericidal activity. Furthermore, we found that mice deficient in SAA1/2 were more susceptible to infection by S. aureus In addition, the expression of SAA in infected skin was regulated by interleukin-6. Taken together, these findings support a key role of the SAA in host defense and may provide a novel therapeutic strategy for cutaneous bacterial infection.

The interaction between serum amyloid A and Toll-like receptor 2 pathway regulates inflammatory cytokine secretion in human gingival fibroblasts.

Serum amyloid A (SAA) has been identified to trigger inflammation response, and play a crucial role in chronic inflammatory diseases. However, the regulatory mechanism of SAA still remains unclear during the development of periodontitis METHODS: SAA mRNA and protein expression were detected in healthy and inflammatory gingival tissues using real-time polymerase chain reaction (PCR) and immunohistochemistry. Human recombinant SAA (Apo-SAA), Pam3CSK4 (a Toll-like receptor (TLR) 2 ligand), siRNA-SAA, or TLR2 neutralizing antibody was applied to treat human gingival fibroblasts, respectively, or combined. SAA, TLRs, and inflammatory cytokines interleukin (IL)-6 and IL-8 were analyzed by real-time PCR, western blotting, or enzyme-linked immunosorbent assay. SAA expression increased in human inflammatory gingival tissues from patients with periodontitis (P<0.05). Apo-SAA could increase not only the mRNA expression of TLR2 (P<0.05), but also IL-6 and IL-8 mRNA and protein levels (P<0.05) which was suppressed by TLR2 antibody in human gingival fibroblasts. Pam3CSK4 increased SAA, IL-6, and IL-8 levels (P<0.05). However, the expression of SAA, IL-6, and IL-8 decreased after transfection of siRNA-SAA (P<0.05). SAA not only increases in inflammatory gingiva, but also triggers inflammatory cytokine secretion via interacting with TLR2 pathway in human gingival fibroblasts, which indicates that SAA is involved in periodontal inflammation.

Differential expression of bovine major acute phase proteins, cytokines and metabolic indicator genes in clinical endometritis cows

Among the uterine diseases, clinical endometritis (CE) is a major challenge to livestock farming as it causes sub- or infertility problems in dairy animals. The aim of this study was to evaluate the expression of cytokines (IL- 1β, TNF-α, IL-6, and IL-8), acute phase proteins [APPs; haptoglobin (Hp), serum amyloid A (SAA) and alpha-1 acid glycoprotein (AGP)] and energy indicators [leptin and insulin-like growth factor (IGF)-1] genes in uterine tissue of CE affected cows. The uterine biopsy from CE cows (4) and non-endometritis cows (4) was processed for quantitative real-time PCR to study the mRNA expression of these innate immune molecules. We observed that mRNA expression of SAA, IL-1β, IL-8 and leptin genes were significantly up-regulated while, TNF-α and IGF-I genes were significantly down-regulated in CE cows. It can be concluded that bovine APPs, cytokines and energy indicators genes are differentially expressed in CE affected cows.

Temporal Effects of High Fishmeal Diet on Gut Microbiota and Immune Response in Clostridium perfringens-Challenged Chickens

Necrotic enteritis (NE) caused by Clostridium perfringens is responsible for huge financial losses in the poultry industry annually. A diet highly supplemented with fishmeal is one factor predisposing chickens to the development of clinical NE. However, the effects of fishmeal-rich diets on the gut microbiota and immune response in chickens with C. perfringens challenge over the long-term are not well-understood. Here, a chicken NE model was established in which chickens were fed high fishmeal diet and subsequently infected with C. perfringens (FM/CP). Two control groups of chickens, one that was not infected and had a high fishmeal feeding (FM) and another group only infected with C. perfringens with basic diets (CP), were used as comparators. We analyzed the gut microbiota and immune response of the three groups at the age of 20, 24 [1 day post-infection (dpi)] and 30 days (7 dpi) using 16S rDNA sequencing and real-time PCR, respectively. We found that the composition of the gut microbiota had significant shifted in both the CP and FM/CP groups, although the CP group did not have intestinal lesions. The structure of the gut microbiota in C. perfringens-challenged chickens, independent of a high fishmeal diet, had the tendency to return to their non-infection state if the chickens no longer received C. perfringens challenge. Gut microbiota variation with time in challenged chickens with high fishmeal diet feeding was superimposed upon that of non-infected chickens with high fishmeal feeding. For the immune response, the relative expression of IL-8 in the ileum was significantly higher in infected chickens independent of high fishmeal feeding than in non-infected chickens. However, the expression of alpha 1-acid glycoprotein (AGP) and serum amyloid A (SAA) genes in chicken liver were significantly increased in FM/CP compared to the other groups. In conclusion, high fishmeal feeding induced significant changes to the structure of chicken gut microbiota over time and such changes provided an opening for C. perfringens infection to progress to NE. The relative expression of AGP and SAA in liver tissue may be used as diagnostic biomarkers for poultry NE but such an indication requires further investigation.

Endometrial expression of the acute phase molecule SAA is more significant than HP in reflecting the severity of endometritis

This study investigated the correlation between endometrial local expressions of serum amyloid A (SAA) and haptoglobin (Hp) and severity of endometritis in 20 Chinese Holstein dairy cows at 40–60 days postpertum, aged 3–6, and 2–5 parities. Endometrial biopsies were collected and categorized into normal, mild endometritis, and severe endometritis based on clinical signs and histopathology. The protein and mRNA expression of SAA and Hp in endometrial tissue were measured using western blot and real-time PCR, respectively. Furthermore, bovine endometrial epithelial cells were isolated and cultured in vitro. The protein and mRNA expression of SAA and Hp were also determined in the cells treated with increasing concentrations of lipopolysaccharide (LPS; 0, 1, 5, 10 μg/ml). The results showed that both of protein and mRNA of SAA was increased in endometritis or in LPS-stimulated cells, and the increases were positively correlated with severity of endometritis in vivo or LPS stimulation strength in vitro. Meanwhile, protein expression of Hp were also increased in endometritis or in LPS-stimulated cells, but the increases were negatively correlative with severity of inflammation as well as mRNA expression of Hp in vivo or in vitro. Therefore, our results suggest that endometrial local expression of SAA is more significant than Hp as a potential biomarker to assess severity of endometritis in cows.

Toll-like receptor signalling induces the expression of serum amyloid A in epidermal keratinocytes and dermal fibroblasts.

Toll-like receptors (TLRs) play critical roles in innate immune response by sensing pathogen- or damage-associated molecular patterns. Epidermal keratinocytes and dermal fibroblasts also produce proinflammatory cytokines and chemokines under stimulation with TLR ligands. Serum amyloid A (SAA) is an essential factor in the pathogenesis of secondary amyloidosis, and also has immunomodulatory functions. SAA are produced mainly by hepatocytes but also by a variety of cells, including immune cells, endothelial cells, synoviocytes, and epidermal keratinocytes. However, SAA expression in human dermal fibroblasts has not been shown to date. To investigate the effect of TLR ligands on SAA expression in epidermal keratinocytes and dermal fibroblasts. We investigated whether TLR ligands induce the expression of SAA in normal human epidermal keratinocytes (NHEKs) and normal human dermal fibroblasts (NHDFs) by real-time quantitative PCR and ELISA. The effect of SAA on its own expression in NHDFs was also studied. SAA expression was induced via nuclear factor-κB by TLR1/2, 3, 5 and 2/6 ligands in NHEKs. In NHDFs, TLR1/2 and TLR2/6 ligands increased SAA expression. SAA further induced its own expression via TLR1/2 and NF-κB in NHDFs, as previously reported for NHEKs. Our results provide new evidence that the skin's innate immune response contributes to the production of SAA, which might lead to an increased risk of systemic complications such as secondary amyloidosis of recessive dystrophic epidermolysis bullosa.

λ-Carrageenan initiates inflammation via activation of heterodimers TLR2/6 and TLR4/6

Abstract λ-Carrageenan (λCGN) is frequently used to model local inflammation, however, the mechanism by which λCGN functions has not been fully examined. Swine whole blood was stimulated with λCGN and biomarkers were evaluated. Monocyte Chemotactic Protein-1(MCP-1) and Interleukin-8 protein levels were increased, while Serum Amyloid A (SAA) and Tumor Necrosis Factor-α (TNFα) protein levels were unchanged. Gene expression of MCP-1, Phosphatidylinositol 3-Kinase, and Alveolar Macrophage Chemotactic–II were increased; gene expression of SAA, Interleukin-6, and TNFα were unchanged; and gene expression of Thrombospondin-2 Precursor were decreased. Assessment of which TLRs (Toll-Like Receptors) were involved in the λCGN activation pathway, HEK-293 cells transfected with one plasmid containing either TLR2 or TLR4, along with a second plasmid to release SEAP (secreted embryonic alkaline phosphatase) upon NFκB activation were stimulated with λCGN. TLR2 and TLR4 both showed increased SEAP release after λCGN stimulation. The lack of TNFα production after λCGN stimulation suggested that it was not working through a classic TLR4 homodimer. To determine if a common mechanism could explain these results, RNA silencing studies were initiated. TLR6 was silenced in SEAP HEK-293 cells containing a plasmid for either TLR2 or TLR4. In both cell lines where TLR6 was silenced, λCGN was unable to induce a SEAP response, while these cells maintained responsiveness to a TLR1/2 ligand and a TLR 4 ligand, respectively. These results suggest that λCGN initiates inflammation via TLR2/6 and TLR4/6 heterodimers.

Augmented Serum Amyloid A1/2 Mediated by TNF-induced NF-κB in Human Serous Ovarian Epithelial Tumors.

Tumor necrosis factor-α (TNF) is well known to be involved in the immune system and ovarian inflammation. Ovarian cancer is an inflammation-related malignancy that lacks early screening strategies, resulting in late diagnosis followed by high mortality. Based on our previous data, TNF induced abundant serum amyloid A (SAA), an acute phase protein linked to inflammation, in ovarian granulosal cells. To date, the regulation and expression of SAA in ovarian cancer is not fully elucidated. Here, we investigated the relationship between TNF and SAA by comparing human normal ovarian tissues and serous ovarian tumors. We found that SAA1/2 was significantly expressed in tumor tissues, but no or trace expression levels in normal tissues. TNF was also significantly upregulated in ovarian tumor tissues compared to normal tissues. Moreover, TNF significantly increased SAA1/2 levels in human ovarian cancer cell lines, OVCAR-3 and SKOV-3, in a time-dependent manner. Since the SAA1 promoter contains two nuclear factor (NF)-κB sites, we examined whether TNF regulates SAA1 promoter activity. Deletion analysis revealed that the proximal NF-κB site (−95/−85) played a critical role in regulating TNF-induced SAA1 promoter activity. Within 2 h after intraperitoneal injection of lipopolysaccharide, a product known to stimulate release of TNF, SAA preferably localized to ovarian epithelial cells and the thecal-interstitial layers compared to granulosal cell layers. Based on Gene Expression Omnibus (GEO) database, SAA1/2 and TNF were dominantly expressed in advanced grade ovarian cancer. Taken together, the accumulation of SAA1/2 in ovarian cancer could be mediated by TNF-induced NF-κB activation.

Increased serum amyloid A as potential diagnostic marker for lung cancer: a meta-analysis based on nine studies.

BackgroundPrevious studies have disclosed that serum amyloid A (SAA) is likely involved in the lung cancer pathogenesis and progression. We performed a systematic evaluation and meta-analysis to disclose the correlation between the expression of SAA and lung cancer and to evaluate its value for lung cancer diagnosis.MethodsWe searched the relevant articles from the databases of Medline, Embase, Cochrance Library and Web of Science and calculated the standardized mean difference (SMD) with 95 % confidence interval (CI) to assess the expression difference of SAA between lung cancer and normal patients. Moreover, we counted the positive rate, sensitivity and specificity and drew a summary receiver operating characteristic curve (SROC) to evaluate the diagnostic value of SAA for lung cancer.ResultsA total of nine studies with 1392 individuals were included in this analysis. The results showed an increased SAA was correlated with the incidence of lung cancer (P < 0.001), especially with the lung squamous cell carcinoma (LSCC) (p = 0.012). The overall sensitivity and specificity of SAA for discerning lung cancer was 0.59 (95 % CI: 0.54–0.63) and 0.92 (95 % CI: 0.88–0.95), respectively. The area under the SROC curve was 0.9066 (SE = 0.0437).ConclusionsIncreased SAA in lung cancer was intimately correlated with the development and progression of lung cancer. A higher specificity of SAA suggested that it should be a significant biomarker for discerning lung cancer from normal individuals, especially for LSCC (p = 0.012).

Structure and Expression of Different Serum Amyloid A (SAA) Variants and their Concentration-Dependent Functions During Host Insults.

Serum amyloid A (SAA) is, like C-reactive protein (CRP), an acute phase protein and can be used as a diagnostic, prognostic or therapy follow-up marker for many diseases. Increases in serum levels of SAA are triggered by physical insults to the host, including infection, trauma, inflammatory reactions and cancer. The order of magnitude of increase in SAA levels varies considerably, from a 10- to 100-fold during limited inflammatory events to a 1000-fold increase during severe bacterial infections and acute exacerbations of chronic inflammatory diseases. This broad response range is reflected by SAA gene duplications resulting in a cluster encoding several SAA variants and by multiple biological functions of SAA. SAA variants are single-domain proteins with simple structures and few post-translational modifications. SAA1 and SAA2 are inducible by inflammatory cytokines, whereas SAA4 is constitutively produced. We review here the regulated expression of SAA in normal and transformed cells and compare its serum levels in various disease states. At low concentrations (10-100 ng/ml), early in an inflammatory response, SAA induces chemokines or matrix degrading enzymes via Toll-like receptors and functions as an activator and chemoattractant through a G protein-coupled receptor. When an infectious or inflammatory stimulus persists, the liver continues to produce more SAA (> 1000 ng/ml) to become an antimicrobial agent by functioning as a direct opsonin of bacteria or by interference with virus infection of host cells. Thus, SAA regulates innate and adaptive immunity and this information may help to design better drugs to treat specific diseases.

Serum amyloid A expression in the breast cancer tissue is associated with poor prognosis.

BackgroundSerum amyloid A (SAA), an acute-phase protein, is expressed primarily in the liver, and recently found also expressed in cancer tissues. However, its expression and prognostic value in breast cancer have not been described.ResultsSAA protein was found expressed in tumor cells in 44.2% cases and in TAM in 62.5% cases. FISH showed more frequent SAA mRNA expression in TAM than in tumor cells (76% versus 12%, p < 0.001), and a significant association between the frequencies of SAA mRNA expression in TAM and tumor cells (rs = 0.603, p < 0.001). The immunoreactivities of SAA protein in TAM and tumor cells were both associated with lymphovascular invasion and lymph node metastasis. Moreover, SAA-positivity in TAMs was associated with larger tumor-size, higher histological-grade, negative estrogen-receptor and progesterone-receptor statuses, and HER-2 overexpression. It was also linked to worse recurrence-free survival in a multivariable regression model.MethodsImmunohistochemistry was applied on the tumor tissues from 208 breast cancer patients to evaluate the local SAA-protein expression with additional CD68 stain to identify the tumor-associated macrophage (TAM) on the serial tissue sections. Fluorescent in situ hybridization (FISH) was conducted on serial tissue sections from 25 of the 208 tumors to examine the expression and location of SAA mRNA.ConclusionsOur results suggested that the TAMs may be a pivotal and main source of SAA production in tumor microenvironment of breast cancer. SAA immunoreactivity in TAM is associated with worse recurrence-free survival, and is therefore a biomarker candidate for postoperative surveillance and perhaps a therapeutic target for breast cancer.

Immunostains Used to Subtype Hepatic Adenomas Do Not Distinguish Hepatic Adenomas From Hepatocellular Carcinomas.

Immunostains are used to subtype hepatic adenomas to stratify for the risk of malignant transformation. The most common panel of immunostains used for this purpose includes liver fatty acid-binding protein (LFABP), serum amyloid A (SAA) protein, C-reactive protein (CRP), and glutamine synthetase (GS). Importantly, some pathologists use these stains in an attempt to distinguish hepatocellular carcinomas (HCC) from hepatic adenomas. However, there are limited data on the performance of these stains in HCCs. To investigate the staining characteristics of HCCs, we studied 159 HCCs (92 well-differentiated, 67 moderately differentiated, and 7 poorly differentiated) and 7 fibrolamellar carcinomas for the expression of LFABP, SAA, CRP, and GS. All of the stains were positive in at least a subset of HCCs: SAA was positive in 27 of 159 (17%), CRP in 86 of 159 (54%), and GS in 23 of 47 (49%) cases; LFABP showed loss of staining in 36 of 159 (23%) cases. Fibrolamellar carcinomas were consistently CRP positive (7 of 7 cases) and frequently showed loss of LFABP (4 of 7 cases). There was no association between expression of SAA, CRP, and GS as well as loss of LFABP expression and other clinicopathologic features. HCCs with loss of LFABP were more frequently associated with negative GS expression (11 of 14 cases, P=0.02). These data show that immunostains used to subtype hepatic adenomas are not useful for distinguishing HCCs from hepatic adenomas and should be used only after a diagnosis of hepatic adenoma has been made using other criteria.

Production of serum amyloid A in equine articular chondrocytes and fibroblast-like synoviocytes treated with proinflammatory cytokines and its effects on the two cell types in culture.

To investigate the role of the major equine acute phase protein serum amyloid A (SAA) in inflammation of equine intraarticular tissues. Articular chondrocytes and fibroblast-like synoviocytes (FLSs) from 8 horses (4 horses/cell type). Chondrocytes and FLSs were stimulated in vitro for various periods up to 48 hours with cytokines (recombinant interleukin [IL]-1β, IL-6, tumor necrosis factor-α, or a combination of all 3 [IIT]) or with recombinant SAA. Gene expression of SAA, IL-6, matrix metalloproteinases (MMP)-1 and -3, and cartilage-derived retinoic acid-sensitive protein were assessed by quantitative real-time PCR assay; SAA protein was evaluated by immunoturbidimetry and denaturing isoelectric focusing and western blotting. All cytokine stimulation protocols increased expression of SAA mRNA and resulted in detectable SAA protein production in chondrocytes and FLSs. Isoforms of SAA in lysed chondrocytes and their culture medium corresponded to those previously detected in synovial fluid from horses with joint disease. When exposed to SAA, chondrocytes and FLSs had increased expression of IL-6, SAA, and MMP3, and chondrocytes had increased expression of MMP-1. Chondrocytes had decreased expression of cartilage-derived retinoic acid-sensitive protein. Upregulation of SAA in chondrocytes and FLSs stimulated with proinflammatory cytokines and the proinflammatory effects of SAA suggested that SAA may be involved in key aspects of pathogenesis of the joint inflammation in horses.