Serum amyloid A expression in liver promotes synovial macrophage activation and chronic arthritis via NFAT5.

Nuclear factor of activated T-cells 5 (NFAT5), an osmo-sensitive transcription factor, can be activated by isotonic stimuli, such as infection. It remains unclear, however, whether NFAT5 is required for damage-associated molecular pattern-triggered (DAMP-triggered) inflammation and immunity. Here, we found that several DAMPs increased NFAT5 expression in macrophages. In particular, serum amyloid A (SAA), primarily generated by the liver, substantially upregulated NFAT5 expression and activity through TLR2/4-JNK signalling pathway. Moreover, the SAA-TLR2/4-NFAT5 axis promoted migration and chemotaxis of macrophages in an IL-6- and chemokine ligand 2-dependent (CCL2-dependent) manner in vitro. Intraarticular injection of SAA markedly accelerated macrophage infiltration and arthritis progression in mice. By contrast, genetic ablation of NFAT5 or TLR2/4 rescued the pathology induced by SAA, confirming the SAA-TLR2/4-NFAT5 axis in vivo. Myeloid-specific depletion of NFAT5 also attenuated SAA-accelerated arthritis. Of note, inflammatory arthritis in mice strikingly induced SAA overexpression in the liver. Conversely, forced overexpression of the SAA gene in the liver accelerated joint damage, indicating that the liver contributes to bolstering chronic inflammation at remote sites by secreting SAA. Collectively, this study underscores the importance of the SAA-TLR2/4-NFAT5 axis in innate immunity, suggesting that acute phase reactant SAA mediates mutual interactions between liver and joints and ultimately aggravates chronic arthritis by enhancing macrophage activation.

The serum amyloid A3 promoter-driven luciferase reporter mice is a valuable tool to image early renal fibrosis development and shows the therapeutic effect of glucosyl-hesperidin treatment.

Tubulointerstitial fibrosis is a progressive process affecting the kidneys, causing renal failure that can be life-threatening. Thus, renal fibrosis has become a serious concern in the ageing population; however, fibrotic development cannot be diagnosed early and assessed noninvasively in both patients and experimental animal models. Here, we found that serum amyloid A3 (Saa3) expression is a potent indicator of early renal fibrosis; we also established in vivo Saa3/C/EBPß-promoter bioluminescence imaging as a sensitive and specific tool for early detection and visualization of tubulointerstitial fibrosis. Saa3 promoter activity is specifically upregulated in parallel with tumor necrosis factor α (TNF-α) and fibrotic marker collagen I in injured kidneys. C/EBPß, upregulated in injured kidneys and expressed in tubular epithelial cells, is essential for the increased Saa3 promoter activity in response to TNF-α, suggesting that C/EBPß plays a crucial role in renal fibrosis development. Our model successfully enabled visualization of the suppressive effects of a citrus flavonoid derivative, glucosyl-hesperidin, on inflammation and fibrosis in kidney disease, indicating that this model could be widely used in exploring therapeutic agents for fibrotic diseases.

Thymol and Carvacrol Affect Hybrid Tilapia through the Combination of Direct Stimulation and an Intestinal Microbiota-Mediated Effect: Insights from a Germ-Free Zebrafish Model.

BACKGROUND: Essential oils (EOs) are commonly used as animal feed additives. Information is lacking on the mechanisms driving the beneficial effects of EOs in animals, especially the role played by the intestinal microbiota of the host. OBJECTIVE: The purpose of this study was to clarify the relative contribution of direct effects of EOs on the physiology and immune system of tilapia and indirect effects mediated by the intestinal microbiota by using a germ-free zebrafish model. METHODS: Juvenile hybrid tilapia were fed a control diet or 1 of 4 treatment diets containing 60-800 mg Next Enhance 150 (NE) (an EO product containing equal levels of thymol and carvacrol)/kg for 6 wk. The key humoral and cellular innate immune parameters were evaluated after the feeding period. In another experiment, the gut microbiota of tilapia fed a control or an NE diet (200 mg/kg) for 2 wk were transferred to 3-d postfertilization (dpf) germ-free (GF) zebrafish, and the expression of genes involved in innate immunity and tight junctions was evaluated in zebrafish at 6 dpf. Lastly, NE was directly applied to 3-dpf GF zebrafish at 3 doses ranging from 0.2 to 20 mg/L, and the direct effect of NE on zebrafish was evaluated after 1 and 3 d. RESULTS: NE supplementation at 200 mg/kg enhanced phagocytosis activity of head kidney macrophages (×1.36) (P < 0.05) and plasma lysozyme activity (×1.69) of tilapia compared with the control (P < 0.001), indicating an immunostimulatory effect. Compared with those colonized with control microbiota, GF zebrafish colonized with NE microbiota showed attenuated induction of immune response marker genes serum amyloid a (Saa; ×0.62), interleukin 1ß (Il1ß; ×0.29), and interleukin 8 (Il8; ×0.62) (P < 0.05). NE treatment of GF zebrafish at 2 and 20 mg/L for 1 d upregulated the expression of Il1ß (×2.44) and Claudin1 (×1.38), respectively (P < 0.05), whereas at day 3 the expression of Occludin2 was higher (×3.30) in the 0.2-mg NE/L group compared with the GF control (P < 0.05). CONCLUSION: NE may affect the immunity of tilapia through a combination of factors, i.e., primarily through a direct effect on host tissue (immune-stimulating) but also an indirect effect mediated by microbial changes (immune-relieving).

Effects of the Dietary ω3:ω6 Fatty Acid Ratio on Body Fat and Inflammation in Zebrafish (Danio rerio).

The diets of populations in industrialized nations have shifted to dramatically increased consumption of ω6 polyunsaturated fatty acids (PUFA), with a corresponding decrease in the consumption of ω3 PUFA. This dietary shift may be related to observed increases in obesity, chronic inflammation, and comorbidities in the human population. We examined the effects of ω3:ω6 fatty acid ratios in the context of constant total dietary lipid on the growth, total body fat, and responses of key inflammatory markers in adult zebrafish (Danio rerio). Zebrafish were fed diets in which the ω3:ω6 PUFA ratios were representative of those in a purported ancestral diet (1:2) and more contemporary Western diets (1:5 and 1:8). After 5 mo, weight gain (fat free mass) of zebrafish was highest for those that received the 1:8 ratio treatment, but total body fat was lowest at this ratio. Measured by quantitative real-time RT-PCR, mRNA levels from liver samples of 3 chronic inflammatory response genes (C-reactive protein, serum amyloid A, and vitellogenin) were lowest at the 1:8 ratio. These data provide evidence of the ability to alter zebrafish growth and body composition through the quality of dietary lipid and support the application of this model to investigations of human health and disease related to fat metabolism.

Characterization and functional classification of American lobster (Homarus americanus) immune factor transcripts.

The American lobster (Homarus americanus) is the most important commercially exploited marine species in Canada. Very little is known about the H. americanus molecular humoral immune response or how to determine if a seemingly healthy lobster is infected with a pathogen. The goal of this work is to characterize several important H. americanus immune genes as well as highlight and classify hundreds of others into functional immune groups. The protein sequence of H. americanus acute phase serum amyloid protein A (SAA) was found to be similar to that of vertebrate SAA, and is likely a good clinical marker for immune activation in lobsters and some crustaceans. Additionally, only one gene, Trypsin 1b, was found to be differentially regulated during bacterial, microparasitic and viral challenges in lobster and is likely critical for the activation of the H. americanus immune response. Bioinformatic analysis was used to functionally annotate, 263 H. americanus immune genes and identify the few shared patterns of differential gene expression in lobsters in response to bacterial, parasitic and viral challenge. Many of the described immune genes are biomarker candidates which could be used as clinical indicators for lobster health and disease. Biomarkers can facilitate early detection of pathogens, or anthropomorphic stressors, so that mitigation strategies can be developed in order to prevent the devastating economic losses that have occurred in Southern New England, USA. This work is contributes to further our understanding of how the lobster immune system works and how it can be used to maintain the health and sustainability of the overall American lobster fishery.

Bovine colostrum improves intestinal function following formula-induced gut inflammation in preterm pigs.

BACKGROUND & AIMS: Only few hours of formula feeding may induce proinflammatory responses and predispose to necrotizing enterocolitis (NEC) in preterm pigs. We hypothesized that bovine colostrum, rich in bioactive factors, would improve intestinal function in preterm pigs following an initial exposure to formula feeding after some days of total parenteral nutrition (TPN). METHODS: After receiving TPN for 2 days, preterm pigs were fed formula (FORM, n = 14), bovine colostrum (COLOS, n = 6), or formula (6 h) followed by bovine colostrum (FCOLOS, n = 14). Intestinal lesions, function, and structure, abundance and location of bacteria, and inflammation markers were investigated. RESULTS: NEC severity and interleukins (IL)-1ß and -8 protein concentrations were lower, while villus height, galactose absorption, and brush-border enzyme activities were increased in the distal small intestine in COLOS and FCOLOS pigs, relative to FORM pigs. Intestinal gene expression of serum amyloid A, IL-1ß, -6 and -8, and bacterial abundance, correlated positively with NEC severity of the distal small intestine. CONCLUSIONS: Bovine colostrum restores intestinal function after initial formula-induced inflammation in preterm pigs. Further studies are required to test if bovine colostrum may also benefit preterm infants during the challenging transition from total parenteral nutrition to enteral nutrition, when human milk is unavailable.

Towards a better understanding of salivary and meat juice acute phase proteins determination in pigs: an expression study.

Acute phase proteins (APPs) determination in different fluids like serum, saliva and meat juice measured with ultrasensitive assays can be used to evaluate the disease status of porcine populations under field conditions. Liver is the main production site of serum APPs, but the origin of APPs that can be determined in body fluids different from blood remains unknown. The objective of this study was to clarify the origin of three APPs: C-reactive protein (CRP), serum amyloid A (SAA) and haptoglobin (Hp) in saliva and meat juice. The mRNA expression of these proteins was measured in liver, salivary gland and diaphragmatic muscle by quantitative PCR and compared with the protein levels in serum, saliva and meat juice, respectively in healthy and naturally diseased animals. As expected, concentrations of all APP were significantly higher in all body fluids from diseased animals. Levels of all APPs mRNA were very low in diaphragmatic muscle tissue, and the expression was independent of the disease status. In contrast, we found higher expression levels of SAA and Hp mRNA in the salivary gland of diseased animals, while CRP mRNA was not detected. Our data indicate that the APP present in meat juice derived predominantly from serum. This assumption is also supported by the good correlation of the levels of both proteins in meat juice with those in serum. Further, the lower variability of the APP levels within the two groups of animals, suggests meat juice as an alternate sampling material. The APP levels that are determined in saliva, however, appear to result from an increased local production except for CRP, indicating that the salivary gland responds to disease. These findings are relevant for the establishment of saliva as the preferred diagnostic sample for health monitoring programmes, due to the technical and ethical advantages of the collection.

Hepatic and extrahepatic expression of serum amyloid A3 during lactation in dairy cows.

Serum amyloid A3 (SAA3) is the predominant SAA isoform secreted by mammary epithelial cells in dairy cows; it is also expressed in bovine adipose tissue (AT). The adipokine SAA3 is linked to obesity and insulin resistance of AT and the respective inflammatory response, at least in mice. Dietary treatment with conjugated linoleic acids (CLA) reportedly also affects insulin sensitivity and inflammatory status in monogastrics. Both SAA3 and CLA thus seem to alter similar functions. Based on changes in insulin sensitivity and the inflammatory status throughout lactation, we hypothesized that the mRNA abundance of SAA3 in various tissues might be regulated as well and that CLA could be a modulator of SAA3 mRNA expression. In 2 trials, 21 pluriparous and 25 primiparous Holstein cows were fed 100g/d of a CLA or a control fat supplement from d 1 to 182 or 105 postpartum, respectively. Biopsies from liver and subcutaneous (s.c.) AT from pluriparous cows and samples from 3 different visceral AT and 3 s.c. AT, muscle, mammary gland, and liver tissue from slaughtered primiparous cows were obtained. In an adipocyte cell culture system, cell samples were collected during differentiation of bovine preadipocytes at d 0, 2, 6, 8, 10, 12, and 13 relative to the onset of differentiation. The SAA3 mRNA abundance in tissues and in differentiating bovine preadipocytes was measured by real-time PCR. The presence of the SAA protein was confirmed by Western blotting. Treatment with CLA yielded only few and inconsistent effects on SAA3 mRNA abundance. In both trials, SAA3 mRNA peaked at d 1 postpartum in all tissues except in mesenteric AT, in which the change was not significant. The highest SAA3 mRNA expression was observed in the mammary gland, followed by omental AT. The SAA protein was present in the visceral and s.c. AT depots investigated. Adipocytes as one source of SAA3 were confirmed by the SAA3 mRNA profile in differentiating adipocytes. The longitudinal changes observed point to SAA3 being involved in the inflammatory situation around parturition.

Chicken amyloid arthropathy: serum amyloid A, interleukin-1beta, interleukin-6, tumour necrosis factor-alpha and nitric oxide profile in acute phase (12th hour).

Acute phase response (APR) is part of the early defense system, which is triggered by different stimuli including, infection, trauma, stres, inflammation and neoplasia. The APR complex is a reaction which induces homeostasis and recovery. In this research, serum amyloid A (SAA), interlaukin (IL)-1beta, IL-6, tumour necrosis factor alpha (TNF-alpha) and nitric oxide (NO) levels were measured 12 hours following injection. For this purpose, Thirty-two 5 weeks old laying chicken were allocated into four groups and intra-articular injections of Freund's adjuvant were used to induce amylod arthropathy in Groups II, III and IV. Vitamin A in group II, and methylprednisolone in group IV were added to enhance and to reduce the severity of amyloidosis, respectively. At the end of the research, it was observed that TNF-alpha and NO increased significantly (P < 0.05) in vitamin A and methylprednisolone groups whereas SAA decreased significantly (P < 0.05) in all groups. It was also observed that IL-6 increased (P < 0.05) in vitamin A group and decreased in all other gorups however, IL-1beta decreased in vitamin A and methylprednisolone groups, while it was increased in the control group. The results of this study suggest that there is a positive correlation between serum TNF-alpha levels in acute and chronic phase in chickens with amyloid arthropathy.

A transcriptomic analysis of American lobster (Homarus americanus) immune response during infection with the bumper car parasite Anophryoides haemophila.

Anophryoides haemophila is an important protistan parasite of American lobster, Homarus americanus, as it has been found to infect lobsters in the wild as well as causing major losses of lobsters maintained in commercial holding facilities. Expression of over 14,500 H. americanus hepatopancreatic genes were monitored during an A. haemophila infection challenge in order to elucidate molecular mechanisms involved in the lobster immune response. One hundred and forty-five genes were found to be differentially expressed during infection. For many genes, this study is the first to link their expression to an immune response to a known lobster pathogen. Several of the genes have previously been linked to crustacean or invertebrate immune response including: several anti-lipopolysaccharide factor isoforms (ALFHa), acute phase serum amyloid protein A (SAA), a serine protease inhibitor, a toll-like receptor, several haemocyanin subunits, phagocyte signaling-impaired protein, vitelline membrane outer layer protein-1, trypsin, and a C-type lectin receptor. Microarray results were verified using RT-qPCR and agreement was good between the two methods. The expression of six ALFHa isoforms was monitored via microarray where ALFHa-1, ALFHa-2, ALFHa-4 and ALFHa-6 were differentially expressed while ALFHa-3 and ALFHa7 were not. RT-qPCR analysis confirmed that ALFHa-1, ALFHA-2 and ALFHa-4 expression increased during infection with a peak at 5-7weeks for ALFHa-1 and 10weeks for ALFHa-2 and ALFHa-4. This suggests that different ALFHa isoforms are temporally expressed during A. haemophila infection. Importantly, these results provide evidence that different ALFHa isoforms have more significant roles in responding to A. haemophila infection. Significant increases in SAA gene expression were also found, corroborating previous findings of increased SAA expression during Aerococcus viridans infections; highlighting the importance of SAA as a marker of H. americanus immune activation and potential indicator of H. americanus health.

Diet supplement CoQ10 delays brain atrophy in aged transgenic mice with mutations in the amyloid precursor protein: an in vivo volume MRI study.

We tested the hypotheses that supplemental intake of the diet supplement Coenzyme Q10 (CoQ10) could delay brain atrophy in double transgenic amyloid precursor protein (APP) / presenilin 1 (PS1), single transgenic APP and PS1 as well as wild type mice by volume MR image in vivo. One hundred and twelve mice (28 APP/PS1, 28 APP, 28 PS1 and 28 wild types) were studied. Half of each genotype group (n = 14 per group) was treated with CoQ10 2400 mg/kg/day, and the other half with placebo for 60 days. Magnetic resonance (MR) images were used to obtain the volumes of the hemispheres and hippocampi. APP / PS1, APP, PS1 and wild type mice treated with CoQ10 exhibited significantly less atrophy in hemisphere and hippocampus than those receiving placebo. The neuro-protective effect of the CoQ10 on hemispheric volume, and hippocampal volume was related to genotype; greater in APP/PS1 than APP and PS1 mice and less in wild type mice. Our result indicated that CoQ10 may have therapeutic potential in the prevention and treatment of MCI and AD.

Amyloid arthropathy in chickens.

The present paper presents an overview of current knowledge of amyloid arthropathy in chickens, and covers the pathogenesis of amyloidosis in general and in birds, field cases reported, and the studies performed to assess the amyloidogenicity of various agents compared to that of Enterococcus faecalis. An animal model of amyloid arthropathy is presented, as are studies on the pathogenesis of arthropathic and amyloidogenic E. faecalis infections in brown layers. The review concludes with a description of the pathology of amyloid arthropathy, the biochemical characterization of the chicken joint amyloid protein as being of the AA type, investigation of the serum amyloid A (SAA) gene involved, and local SAA mRNA expression in joint and liver.

YY1 represses rat serum amyloid A1 gene transcription and is antagonized by NF-kappa B during acute-phase response.

Serum amyloid A (SAA), one of the major acute-phase proteins, increases several hundredfold in concentration in plasma following acute inflammation, primarily as a result of a 200-fold increase in its transcriptional rate. Functional analysis of the rat SAA1 promoter has identified a 65-bp cytokine response unit (CRU; positions -135 to -71) that could confer cytokine responsiveness on a heterologous promoter. Within this CRU, two cis-regulatory elements, corresponding to NF-kappa B- and C/EBP-binding sites, were found to be functionally important and exerted synergistic effects on induced SAA1 expression. In this report, we show that a third transcription factor interacts with the CRU through a region located between the NF-kappa B- and C/EBP-binding sites. On the basis of its gel mobility shift patterns, ubiquitous binding activity, sequence specificity of DNA binding, zinc-dependent binding activity, and gel mobility supershift by specific antibodies, we concluded that this factor is identical to YY1. Methylation interference studies revealed that YY1 binding sequences overlapped with those of NF-kappa B, and gel mobility studies showed that NF-kappa binding to the CRU was effectively inhibited by YY1. Consistent with its presumed antagonistic role to NF-kappa B, YY1 exerted a negative effect on SAA1 expression, whereas disruption of its binding in the promoter elevated basal and cytokine-induced activities. Furthermore, overexpression of YY1 trans-repressed SAA1 promoter activity. Thus, our results demonstrate that SAA1 expression is tightly regulated by an on-off switch of activators and repressors, presumably to ensure that it is expressed only under appropriate physiological conditions.