Plasma Serum Amyloid A Levels Research Articles

Study of age-related changes in plasma metabolites and enzyme activity of healthy small dogs that underwent medical checkups.

In Japan, the importance of medical checkups for pet dogs is increasing. In this study, we retrospectively explored the effects of age on plasma biomarkers in healthy small dogs that underwent medical checkups. Based on the modified American Animal Hospital Association Canine Life Stage Guidelines, 52 healthy small dogs were divided into 3 groups according to their life stage: young adult (1-4 years old), mature adult (5-11 years old), senior (12-15 years old). None of the dogs were obese. Plasma was collected from animals that underwent medical checkups at Muromi Animal Hospital (Fukuoka, Japan). Plasma glucose, triglyceride (TG), total protein, blood urea nitrogen (BUN), creatinine, total cholesterol, and albumin concentrations; alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase (ALP) activities; c-reactive protein (CRP), non-esterified fatty acid, malondialdehyde (MDA), serum amyloid A (SAA), insulin, and adiponectin (ADN) concentrations; glutathione peroxidase (GPx), superoxide dismutase (SOD), malate dehydrogenase (MDH), and lactate dehydrogenase (LDH) activities; and M/L ratio (MDH/LDH) were examined. Changes in the abovementioned plasma biomarker levels were compared between canines in different life stages. Plasma ADN concentrations and GPx, SOD, and MDH activities significantly decreased with age, whereas plasma ALP, BUN, TG, and MDA concentrations gradually increased. Plasma SAA levels measured by the latex agglutination method in 51 of the 52 small dogs that underwent medical checkups were below the detection limit. Plasma ADN concentrations, GPx, SOD activity, and BUN levels may be important biomarkers for clarifying the effect of age in healthy dogs that undergo medical checkups. However, plasma SAA values obtained by the latex agglutination method were not considered an age-related inflammation marker for healthy dogs.

Combined repetitive transcranial magnetic stimulation and medication treatment for depression is associated with serum amyloid a level: Evidence from naturalistic clinical practice.

ObjectiveRepetitive transcranial magnetic stimulation (rTMS) has a positive effect on patients with depressive disorder, while the underpinning molecular mechanism is unknown. Here, we aimed to investigate the effect of rTMS on serum levels of serum amyloid A (SAA) and testosterone in a real-world setting.Materials and methodsIn total, ninety-seven patients with depressive disorder were treated with medicine and rTMS (the rTMS group) while 122 patients were treated using the medicine only (the control group). Plasma levels of SAA (n = 52) and testosterone (n = 37) were measured before and after 2 weeks of treatment, and the treatment effect was evaluated by Hamilton Rating Scale for Depression (HAMD).ResultsThe treatment effect revealed by the percentage of decrease in HAMD in the second week was significantly greater in the rTMS group compared with the control group. No significant difference was found in SAA or testosterone levels between the two groups. However, the percentage of changes in SAA (r = −0.492, p = 0.017) in the second week was significantly correlated with the percentage of decrease in HAMD score in the rTMS group, but not in the control group.ConclusionPatients with depression benefit more from combined rTMS and medication treatment in this naturalistic study. Changes in SAA level, but not testosterone level, were related to depressive remission after 2 weeks’ combined treatment.

Serum amyloid A, a host-derived DAMP in pregnancy?

Serum amyloid A (SAA) is one of the acute phase proteins released primarily from the liver in response to infection, inflammation and trauma. Emerging evidence indicates that SAA may function as a host-derived damage-associated molecular pattern (DAMP) protein to sense danger signals in pregnancy. The plasma SAA levels in maternal circulation are significantly increased in normal parturition, particularly in postpartum, as well as in gestational disorders such as premature preterm rupture of membranes, pre-eclampsia, gestational diabetes, and recurrent spontaneous abortion. It is likely that SAA acts as a non-specific DAMP molecule in response to inflammation and trauma experienced under these conditions. Notably, SAA can also be synthesized locally in virtually all gestational tissues. Within these gestational tissues, under the induction by bacterial products, pro-inflammatory cytokines and stress hormone glucocorticoids, SAA may exert tissue-specific effects as a toll-like receptor 4 (TLR4)-sensed DAMP molecule. SAA may promote parturition through stimulation of inflammatory reactions via induction of pro-inflammatory cytokines, chemokines, adhesion molecules and prostaglandins in the uterus, fetal membranes and placenta. In the fetal membranes, SAA may also facilitate membrane rupture through induction of matrix metalloproteases (MMPs)- and autophagy-mediated collagen breakdown and attenuation of lysyl oxidase-mediated collagen cross-linking. SAA synthesized in extravillous trophoblasts may promote their invasiveness into the endometrium in placentation. Here, we summarized the current understanding of SAA in pregnancy with an aim to stimulate in-depth investigation of SAA in pregnancy, which may help better understand how inflammation is initiated in gestational tissues in both normal and abnormal pregnancies.

Serum amyloid A predicts poor functional outcome in patients with ischemic stroke receiving endovascular thrombectomy: a case control study

BackgroundPost-stroke inflammation contributes to poor outcomes, but its impact on patients with stroke receiving endovascular thrombectomy (EVT) remains unknown.MethodsWe enrolled adult patients with stroke who received EVT, with blood sampling...

Marked Changes in Serum Amyloid A Distribution and High-Density Lipoprotein Structure during Acute Inflammation.

High-density lipoprotein- (HDL-) cholesterol measurements are generally used in the diagnosis of cardiovascular diseases. However, HDL is a complicated heterogeneous lipoprotein, and furthermore, it can be converted into dysfunctional forms during pathological conditions including inflammation. Therefore, qualitative analysis of pathophysiologically diversified HDL forms is important. A recent study demonstrated that serum amyloid A (SAA) can remodel HDL and induce atherosclerosis not only over long periods of time, such as during chronic inflammation, but also over shorter periods. However, few studies have investigated rapid HDL remodeling. In this study, we analyzed HDL samples from patients undergoing orthopedic surgery inducing acute inflammation. We enrolled 13 otherwise healthy patients who underwent orthopedic surgery. Plasma samples were obtained on preoperative day and postoperative days (POD) 1-7. SAA, apolipoprotein A-I (apoA-I), and apolipoprotein A-II (apoA-II) levels in the isolated HDL were determined. HDL particle size, surface charge, and SAA and apoA-I distributions were also analyzed. In every patient, plasma SAA levels peaked on POD3. Consistently, the HDL apoA-I : apoA-II ratio markedly decreased at this timepoint. Native-polyacrylamide gel electrophoresis and high-performance liquid chromatography revealed the loss of small HDL particles during acute inflammation. Furthermore, HDL had a decreased negative surface charge on POD3 compared to the other timepoints. All changes observed were SAA-dependent. SAA-dependent rapid changes in HDL size and surface charge were observed after orthopedic surgery. These changes might affect the atheroprotective functions of HDL, and its analysis can be available for the qualitative HDL assessment.

Synergy between serum amyloid A and secretory phospholipase A2.

Serum amyloid A (SAA) is an evolutionally conserved enigmatic biomarker of inflammation. In acute inflammation, SAA plasma levels increase ~1,000 fold, suggesting that this protein family has a vital beneficial role. SAA increases simultaneously with secretory phospholipase A2 (sPLA2), compelling us to determine how SAA influences sPLA2 hydrolysis of lipoproteins. SAA solubilized phospholipid bilayers to form lipoproteins that provided substrates for sPLA2. Moreover, SAA sequestered free fatty acids and lysophospholipids to form stable proteolysis-resistant complexes. Unlike albumin, SAA effectively removed free fatty acids under acidic conditions, which characterize inflammation sites. Therefore, SAA solubilized lipid bilayers to generate substrates for sPLA2 and removed its bioactive products. Consequently, SAA and sPLA2 can act synergistically to remove cellular membrane debris from injured sites, which is a prerequisite for tissue healing. We postulate that the removal of lipids and their degradation products constitutes a vital primordial role of SAA in innate immunity; this role remains to be tested in vivo.

Course of serum amyloid A (SAA) plasma concentrations in horses undergoing surgery for injuries penetrating synovial structures, an observational clinical study

BackgroundInjuries penetrating synovial structures are common in equine practice and often result in septic synovitis. Significantly increased plasma levels of serum amyloid A (SAA) have been found in various infectious conditions in horses including wounds and septic arthritis. Plasma SAA levels were found to decrease rapidly once the infectious stimulus was eliminated. The purpose of the current study was to investigate the usefulness of serial measurements of plasma SAA as a monitoring tool for the response to treatment of horses presented with injuries penetrating synovial structures. In the current study plasma SAA concentrations were measured every 48 hours (h) during the course of treatment.ResultsA total of 19 horses with a wound penetrating a synovial structure were included in the current study. Horses in Group 1 (n = 12) (injuries older than 24 h) only needed one surgical intervention. Patients in this group had significantly lower median plasma SAA levels (P = 0.001) between 48 h (median 776 mg/L) and 96 h (median 202 mg/L) after surgery. A significant decrease (P = 0.004) in plasma SAA levels was also observed between 96 h after surgery (median 270 mg/L) and 6 days (d) after surgery (median 3 mg/L). Four horses (Group 2) required more than one surgical intervention. In contrast to Group 1 patients in Group 2 had either very high initial plasma concentrations (3378 mg/L), an increase or persistently high concentrations of plasma SAA after the first surgery (median 2525 mg/L). A small group of patients (n = 3) (Group 3) were admitted less than 24 h after sustaining a wound. In this group low SAA values at admission (median 23 mg/L) and peak concentrations at 48 h after surgery (median 1016 mg/L) were observed followed by a decrease in plasma SAA concentration over time.ConclusionsA decrease in plasma SAA concentrations between two consecutive time points could be associated with positive response to treatment in the current study. Therefore, serial measurements of plasma SAA could potentially be used as an additional inexpensive, quick and easy tool for monitoring the treatment response in otherwise healthy horses presented with injuries penetrating synovial structures. However further studies will be necessary to ascertain its clinical utility.

Serum Amyloid A Production Is Triggered by Sleep Deprivation in Mice and Humans: Is That the Link between Sleep Loss and Associated Comorbidities?

Serum amyloid A (SAA) was recently associated with metabolic endotoxemia, obesity and insulin resistance. Concurrently, insufficient sleep adversely affects metabolic health and is an independent predisposing factor for obesity and insulin resistance. In this study we investigated whether sleep loss modulates SAA production. The serum SAA concentration increased in C57BL/6 mice subjected to sleep restriction (SR) for 15 days or to paradoxical sleep deprivation (PSD) for 72 h. Sleep restriction also induced the upregulation of Saa1.1/Saa2.1 mRNA levels in the liver and Saa3 mRNA levels in adipose tissue. SAA levels returned to the basal range after 24 h in paradoxical sleep rebound (PSR). Metabolic endotoxemia was also a finding in SR. Increased plasma levels of SAA were also observed in healthy human volunteers subjected to two nights of total sleep deprivation (Total SD), returning to basal levels after one night of recovery. The observed increase in SAA levels may be part of the initial biochemical alterations caused by sleep deprivation, with potential to drive deleterious conditions such as metabolic endotoxemia and weight gain.

Significant Increase in C-Reactive Protein and Serum Amyloid A in the Early Hours of Paroxysmal Atrial Fibrillation

BackgroundA number of data have been accumulated on inflammation in persistent and permanent atrial fibrillation (AF). Our aim was to study the process in paroxysmal AF (PAF) by measuring plasma concentrations of high-sensitivity C-reactive protein (hs-CRP), serum amyloid A (SAA) and fibrinogen in dynamics.MethodsThe markers were investigated in 51 patients (26 males and 25 females; 59.84 ± 1.60 years) at hospital admission (baseline), 24 hours and 28 days after sinus rhythm restoration. Fifty-two controls (26 males and 26 females; 59.50 ± 1.46 years) were selected.ResultsAt baseline, hs-CRP and SAA concentrations were higher in patients (8.12 ± 0.82 vs. 5.57 ± 0.21 mg/L, P = 0.003; 16.04 ± 0.93 vs. 5.12 ± 0.23 ng/mL, P < 0.001, respectively) and these changes persisted 24 hours after sinus rhythm restoration (8.16 ± 0.71 vs. 5.57 ± 0.21 mg/L, P < 0.001; 12.99 ± 0.75 vs. 5.12 ± 0.23 ng/mL, P < 0.001, respectively). On the 28th day, no significant difference was measured (5.42 ± 0.29 vs. 5.57 ± 0.21 mg/L, P = 0.68; 5.89 ± 0.38 vs. 5.12 ± 0.23 ng/mL, P = 0.08, respectively). At any measurement, fibrinogen levels did not differ between patients and controls (3.30 ± 0.17 vs. 3.22 ± 0.11 g/L, P = 0.70; 3.32 ± 0.11 vs. 3.22 ± 0.11 g/L, P = 0.52; 3.24 ± 0.13 vs. 3.22 ± 0.11 g/L, P = 0.90, respectively).ConclusionPAF is associated with dynamics in hs-CRP and SAA plasma levels. The results suggest that inflammation is closely related to the arrhythmia initiation.

Serum Amyloid A as a Biomarker for Radiation Exposure.

There is a need for minimally invasive biomarkers that can accurately and quickly quantify radiation exposure. Radiation-responsive proteins have applications in clinical medicine and for mass population screenings after a nuclear or radiological incident where the level of radiation exposure and exposure pattern complicate medical triage for first responders. In this study, we evaluated the efficacy of the acute phase protein serum amyloid A (SAA) as a biomarker for radiation exposure using plasma from irradiated mice. Ten-week-old female C57BL6 mice received a 1-8 Gy single whole-body or partial-body dose from a Pantak X-ray source at a dose rate of 2.28 Gy/min. Plasma was collected by mandibular or cardiac puncture at 6, 24, 48 and 72 h or 1-3 weeks postirradiation. SAA levels were determined using a commercially available ELISA assay. Data was pooled to generate SAA μg/ml threshold values correlating plasma SAA levels with radiation dose. SAA levels were statistically significant over control at all exposures between 2 and 8 Gy at 24 h postirradiation but not at 6, 48 and 72 h or 1-3 weeks postirradiation. SAA levels at 1 Gy were not significantly elevated over control at all time points. Total-body-irradiated (TBI) SAA levels at 24 h were used to generate a dose prediction model that successfully differentiated TBI mice into dose received cohorts of control/1 Gy and ≥ 2 Gy groups with a high degree of accuracy in a blind study. Dose prediction of partial-body exposures based on the TBI model correlated increasing predictive accuracy with percentage of body exposure to radiation. Our findings indicate that plasma SAA levels might be a useful biomarker for radiation exposure in a variety of total- and partial-body irradiation settings.

2B.08

Objective: Serum amyloid A (SAA) is an apolipoprotein transported within the high density lipoprotein (HDL) in plasma. The SAA plasma levels increase during inflammatory conditions, e.g., in patients with chronic renal failure (CRF). The SAA-dependent reduction in anti-inflammatory condition of HDL and its pro-inflammatory response in smooth muscle cells was shown previously. The aim of this study was to investigate the signaling pathways of SAA in macrophages and therefore its influence on inflammatory vascular disease. Design and method: THP-1 (human) monocytes were activated via PMA to macrophages and used for monocyte chemoattractant protein-1 (MCP-1) experiments. Murine RAW264.7 monocytes/macrophages were used for nitrite experiments. MCP-1 production was detected by Luminex™ technology. Nitrite production were measured via Griess Assay. Cell viability was determined via MTS assay. Results: SAA accumulates in plasma of patients during conditions of CRF. Whereas there is only a slight increase within CRF stage 1 and 2, the plasma level of SAA further increase during CRF stage 3 to 5. Beside the pro-inflammatory potential of SAA to induce MCP-1 in vascular smooth muscle cells, it also induces MCP-1 secretion in human THP-1 macrophages in a dose-dependent manner. In addition, the production of nitrite was dose-dependently increased in murine RAW264.7 cells. Both, MCP-1 and nitrite production induced by SAA were regulated via TLR and SR-BI receptor activation. The TLR2/4 antagonist oxPAPC and the SR-BI antagonist BLT-1 diminished the SAA-induced MCP-1 and nitrite production. The activation of FPR2 seems not to be involved in the signaling pathway in macrophages after SAA stimulation in that experimental condition. Stimulation with receptor agonists confirmed these findings. The concentration used for agonists/antagonists had no significant influence on cell viability of macrophages. Conclusions: In conclusion, the pro-inflammatory reaction of SAA in macrophages in vitro depends on TLR2/4 and SR-BI activation. The accumulation of SAA plasma levels during CRF may substantially contribute to the increased cardiovascular risk of these patients.

Abstract 114: Serum Amyloid A Plays an Important Role in Making HDL Lose Its Anti-inflammatory Effect on Adipocytes

Adipose tissue inflammation associates with insulin resistance and increased cardiovascular disease risk. HDL has both anti-inflammatory and atheroprotective properties. We recently showed that HDL from healthy humans and lean mice inhibits palmitate-induced monocyte chemotactic factor expression by decreasing lipid raft (LR) content in adipocytes. However, little is known regarding whether inflammation would cause HDL to lose these anti-inflammatory effects on adipocytes. To generate HDL under conditions of sterile inflammation, HDL was purified from plasma of AgNO 3 -injected C57BL/6 mice. In 3T3L-1 adipocytes, “inflamed HDL” did not disrupt the formation of LR or inhibit monocyte chemotactic factor expression. Moreover, inflamed HDL lost its ability to facilitate cholesterol efflux in adipocytes. To determine causal factors of HDL that might be responsible for this loss of anti-inflammatory effect on adipocytes, we investigated role of serum amyloid A (SAA), levels of which are increased up to 1000 fold in HDL by acute inflammation. In a loss of function study, inflamed HDL from AgNO 3 -injectd SAA1/2 double knockout (DKO) mice restored part of its anti-inflammatory and cholesterol efflux capacity. Conversely, in a gain of function study, increasing the SAA content in uninflamed HDL by exposure to 293 HEK cells with lentiviral overexpression of SAA2 resulted in a partial loss of its anti-inflammatory effect and cholesterol efflux capacity. To determine whether HDL from moderately inflamed humans had similar effects on adipocyte inflammation, HDL isolated from patients with systemic lupus erythematosus (n=18) also demonstrated impaired anti-inflammatory effects in adipocytes. The extent of impairment associated positively with plasma SAA levels ( r =0.80; p &lt;0.001), and negatively with cholesterol efflux capacity of the HDL ( r =-0.74; p &lt;0.001). These findings indicate that inflamed HDL loses its anti-inflammatory effect and cholesterol efflux capacity on adipocytes. The presence of SAA in HDL may contribute to the generation of dysfunctional HDL and should be considered as a causal factor, not simply as a biomarker of dysfunctional HDL.

Imbalanced gp130 signalling in ApoE-deficient mice protects against atherosclerosis

ObjectiveInterleukin (IL)-6 is a key modulator of the acute phase response (APR), and while both are implicated in atherosclerosis, the pathological role of specific IL-6 signalling cascades is ill-defined. Since IL-6 employs the cytokine receptor gp130 to primarily activate the STAT3 pathway, here we evaluate whether gp130-dependent STAT3 activation modulates atherosclerosis. MethodsHigh-fat diet-induced atherosclerosis was established in ApoE−/− mice crossed with gp130F/F knock-in mice displaying elevated gp130-dependent STAT3 activation and production of the APR protein, serum amyloid A (SAA). Also generated were gp130F/F:Stat3−/+:ApoE−/− mice displaying genetically-normalised STAT3 activation and SAA levels, and bone marrow chimeras involving ApoE−/− and gp130F/F:ApoE−/− mice. At 10 weeks post high-fat diet, aortic atherosclerotic lesions, including the presence of CD68+ macrophages, and plasma lipid and SAA profiles, were assessed. ResultsAortic plaque development and plasma triglyceride levels in gp130F/F:ApoE−/− mice were significantly reduced (3-fold, P < 0.001) compared to ApoE−/− littermates. By contrast, in gp130F/F:ApoE−/− mice, atherosclerotic plaques contained augmented CD68+ macrophage infiltrates, and plasma SAA levels were elevated, compared to ApoE−/− mice. Atherosclerotic lesion development and plasma triglyceride levels in gp130F/F:ApoE−/− and gp130F/F:Stat3−/+:ApoE−/− mice were comparable, despite a significant (P < 0.05) reduction in macrophage numbers in lesions, and also plasma SAA levels, in gp130F/F:Stat3−/+:ApoE−/− mice. Aortic plaque development and plasma triglyceride levels were comparable in ApoE−/− mice reconstituted with gp130F/F:ApoE−/− (ApoEF/F:ApoE) or ApoE−/− (ApoEApoE) bone marrow cells. ConclusionsDeregulation of gp130/STAT3 signalling augments the APR and macrophage infiltration during atherosclerosis without impacting on the development of aortic plaques.

128: Modulation of atherosclerosis in ApoE-deficient mice by gp130 signalling

Interleukin (IL)-6 is a key modulator of the acute phase response (APR), and while both have been implicated in atherosclerosis, the pathological role of signalling cascades downstream of IL-6 is ill-defined. Since IL-6 employs the cytokine receptor gp130 to primarily activate the STAT3 signalling cascade, here we evaluate whether gp130-dependent STAT3 activation modulates atherosclerosis. High-fat diet-induced atherosclerosis was established in ApoE −/− mice crossed with gp 130 F / F knock-in mice displaying elevated gp130-dependent STAT3 activation and production of the APR protein, serum amyloid A (SAA). Also generated were gp 130 F / F :Stat3 −/+ :ApoE −/− mice displaying genetically-normalised STAT3 activation and SAA levels, and bone marrow chimeras involving ApoE −/− and gp 130 F / F :ApoE −/− mice. At 10 weeks post high-fat diet, aortic atherosclerotic lesions, including the presence of CD68 + macrophages, and plasma lipid and SAA profiles, were assessed. Aortic plaque development and plasma triglyceride levels in gp 130 F / F :ApoE −/− mice were significantly reduced (3-fold, P < 0.001) compared to ApoE −/− littermates. By contrast, in gp 130 F / F :ApoE −/− mice, atherosclerotic plaques contained augmented CD68 + macrophage infiltrates, and plasma SAA levels were elevated, compared to ApoE −/− mice. Atherosclerotic lesion development and plasma triglyceride levels in gp 130 F / F :ApoE −/− and gp 130 F / F :Stat3 −/+ :ApoE −/− mice were comparable, despite a significant ( P < 0.05) reduction in macrophage numbers in lesions, and also plasma SAA levels, in gp 130 F / F :Stat3 −/+ :ApoE −/− mice. Finally, aortic plaque development and plasma triglyceride levels were comparable in ApoE −/− mice reconstituted with gp 130 F / F :ApoE −/− (ApoE F / F :ApoE) or ApoE −/− (ApoEApoE) bone-marrow cells. Deregulation of gp130/STAT3 signalling augments the APR and macrophage infiltration during atherosclerosis without impacting on the development of aortic plaques.

Adipose tissue-derived human serum amyloid a does not affect atherosclerotic lesion area in hSAA1+/-/ApoE-/- mice.

Chronically elevated serum levels of serum amyloid A (SAA) are linked to increased risk of cardiovascular disease. However, whether SAA is directly involved in atherosclerosis development is still not known. The aim of this study was to investigate the effects of adipose tissue-derived human SAA on atherosclerosis in mice. hSAA1+/− transgenic mice (hSAA1 mice) with a specific expression of human SAA1 in adipose tissue were bred with ApoE-deficient mice. The hSAA1 mice and their wild type (wt) littermates were fed normal chow for 35 weeks. At the end of the experiment, the mice were euthanized and blood, gonadal adipose tissue and aortas were collected. Plasma levels of SAA, cholesterol and triglycerides were measured. Atherosclerotic lesion areas were analyzed in the aortic arch, the thoracic aorta and the abdominal aorta in en face preparations of aorta stained with Sudan IV. The human SAA protein was present in plasma from hSAA1 mice but undetectable in wt mice. Similar plasma levels of cholesterol and triglycerides were observed in hSAA1 mice and their wt controls. There were no differences in atherosclerotic lesion areas in any sections of the aorta in hSAA1 mice compared to wt mice. In conclusion, our data suggest that adipose tissue-derived human SAA does not influence atherosclerosis development in mice.

Metabolites of arachidonic acid acting in the small intestine mediate systemic and vascular inflammation in LDLR null mice (832.13)

We previously reported that a Western Diet increased levels of free arachidonic acid (AA) and its metabolites in the small intestine and plasma of LDLR null mice and increased plasma levels of serum amyloid A (SAA). To determine the role of AA metabolites in initiating inflammation, LDLR null mice on a chow diet were or were not administered 15‐hydroxyeicosatetraenoic acid (15‐HETE) at a dose of 5 μg/day (mixed into the chow) or the mice received 5 μg/day subcutaneously (SQ). After two weeks the mice were bled, perfused with saline to remove any remaining blood and the heart was harvested. Plasma levels of SAA were determined by ELISA and levels of free AA and its metabolites were determined in plasma by LC‐ESI‐MS/MS. Plasma SAA levels increased from 6.4 ± 1.9 ug/mL on chow without 15‐HETE to 15 ± 7 ug/mL with oral 15‐HETE (p&lt;0.0001) and 15 ± 8 µg/mL with SQ (p = 0.0004). Plasma levels of free AA increased from 2435 ± 420 ng/mL on chow to 3274 ± 517 ng/mL with oral 15‐HETE (p&lt;0.0001) and 2712 ± 479 ng/mL with SQ (p = 0.001). Three hours after the last SQ dose, plasma 15‐HETE levels were 0.9 ± 0.4 ng/mL on chow, 2.7 ± 1.5 ng/mL after oral (p&lt;0.0001) and 1.5 ± 0.3 ng/mL after SQ 15‐HETE (p&lt;0.0001). 5‐HETE and 12‐HETE levels also increased (p&lt;0.001) and the magnitude of the changes were similar whether the 15‐HETE was administered orally or SQ. We conclude i) 15‐HETE administration increases plasma SAA, and free AA levels to a similar degree whether administered orally or SQ; ii) These results suggest that AA metabolites such as 15‐HETE can act in the small intestine to regulate systemic inflammation.Grant Funding Source: NIH

D‐4F‐mediated reduction in metabolites of arachidonic and linoleic acids in the small intestine is associated with decreased inflammation in low‐density lipoprotein receptor‐null mice (LB708)

Our group hypothesized that intestine is a major site of action for D‐4F, low‐density lipoprotein receptor null (LDLR) mice were fed a Western diet (WD) and administered the peptide subcutaneously (SQ) or orally. Plasma and liver D‐4F levels were 298‐fold and 96‐fold higher, respectively, after SQ administration, whereas D‐4F levels in small intestine were similar whether D‐4F was administered orally or SQ. Levels of metabolites of arachidonic and linoleic acids known to bind with high affinity to D‐4F were significantly reduced in intestine, liver and hepatic bile to a similar degree whether administered SQ or orally. However, levels of 20‐hydroxyeicosatetraenoic acid (HETE), which is known to bind the peptide with low affinity, were unchanged. D‐4F treatment reduced plasma serum amyloid A (SAA) and triglyceride levels and increased HDL‐cholesterol levels after SQ or oral administration. Plasma levels of metabolites of arachidonic and linoleic acids significantly correlated with SAA levels. Feeding 15‐HETE chow diet (without WD) significantly increased plasma SAA and triglyceride levels and decreased HDL‐cholesterol and paraoxonase activity, all of which were significantly enhanced by SQ D‐4F. Our group concludes that D‐4F administration reduces levels of free metabolites of arachidonic and linoleic acids in the small intestine and this is associated with decreased inflammation in LDLR null mice.

HIV infection and drugs of abuse: role of acute phase proteins

BackgroundHIV infection and drugs of abuse such as methamphetamine (METH), cocaine, and alcohol use have been identified as risk factors for triggering inflammation. Acute phase proteins such as C-reactive protein (CRP) and serum amyloid A (SAA) are the biomarkers of inflammation. Hence, the interactive effect of drugs of abuse with acute phase proteins in HIV-positive subjects was investigated.MethodsPlasma samples were utilized from 75 subjects with METH use, cocaine use, alcohol use, and HIV-positive alone and HIV-positive METH, cocaine, and alcohol users, and age-matched control subjects. The plasma CRP and SAA levels were measured by ELISA and western blot respectively and the CD4 counts were also measured.ResultsObserved results indicated that the CRP and SAA levels in HIV-positive subjects who are METH, cocaine and alcohol users were significantly higher when compared with either drugs of abuse or HIV-positive alone. The CD4 counts were also dramatically reduced in HIV-positive with drugs of abuse subjects compared with only HIV-positive subjects.ConclusionsThese results suggest that, in HIV-positive subjects, drugs of abuse increase the levels of CRP and SAA, which may impact on the HIV infection and disease progression.

A novel approach to oral apoA-I mimetic therapy

Transgenic tomato plants were constructed with an empty vector (EV) or a vector expressing an apoA-I mimetic peptide, 6F. EV or 6F tomatoes were harvested, lyophilized, ground into powder, added to Western diet (WD) at 2.2% by weight, and fed to LDL receptor-null (LDLR(-/-)) mice at 45 mg/kg/day 6F. After 13 weeks, the percent of the aorta with lesions was 4.1 ± 4%, 3.3 ± 2.4%, and 1.9 ± 1.4% for WD, WD + EV, and WD + 6F, respectively (WD + 6F vs. WD, P = 0.0134; WD + 6F vs. WD + EV, P = 0.0386; WD + EV vs. WD, not significant). While body weight did not differ, plasma serum amyloid A (SAA), total cholesterol, triglycerides, and lysophosphatidic acid (LPA) levels were less in WD + 6F mice; P < 0.0295. HDL cholesterol and paroxonase-1 activity (PON) were higher in WD + 6F mice (P = 0.0055 and P = 0.0254, respectively), but not in WD + EV mice. Plasma SAA, total cholesterol, triglycerides, LPA, and 15-hydroxyeicosatetraenoic acid (HETE) levels positively correlated with lesions (P < 0.0001); HDL cholesterol and PON were inversely correlated (P < 0.0001). After feeding WD + 6F: i) intact 6F was detected in small intestine (but not in plasma); ii) small intestine LPA was decreased compared with WD + EV (P < 0.0469); and iii) small intestine LPA 18:2 positively correlated with the percent of the aorta with lesions (P < 0.0179). These data suggest that 6F acts in the small intestine and provides a novel approach to oral apoA-I mimetic therapy.

D-4F-mediated reduction in metabolites of arachidonic and linoleic acids in the small intestine is associated with decreased inflammation in low-density lipoprotein receptor-null mice

To test the hypothesis that intestine is a major site of action for D-4F, LDLR(-/-) mice were fed a Western diet (WD) and administered the peptide subcutaneously (SQ) or orally. Plasma and liver D-4F levels were 298-fold and 96-fold higher, respectively, after SQ administration, whereas peptide levels in small intestine only varied by 1.66 ± 0.33-fold. Levels of metabolites of arachidonic and linoleic acids known to bind with high affinity to D-4F were significantly reduced in intestine, liver and hepatic bile to a similar degree whether administered SQ or orally. However, levels of 20-HETE, which is known to bind the peptide with low affinity, were unchanged. D-4F treatment reduced plasma serum amyloid A (SAA) and triglyceride levels (P < 0.03) and increased HDL-cholesterol levels (P < 0.04) similarly after SQ or oral administration. Plasma levels of metabolites of arachidonic and linoleic acids significantly correlated with SAA levels (P < 0.0001). Feeding 15-HETE in chow (without WD) significantly increased plasma SAA and triglyceride levels and decreased HDL-cholesterol and paraoxonase activity (P < 0.05), all of which were significantly ameliorated by SQ D-4F (P < 0.05). We conclude that D-4F administration reduces levels of free metabolites of arachidonic and linoleic acids in the small intestine and this is associated with decreased inflammation in LDL receptor deficient mice.