Dietary patterns and longitudinal change in hip bone mineral density among older men

Studying dietary patterns is often more informative than individual nutrients or foods. We found that a Prudent dietary pattern (rich in vegetables and fish) was associated with reduced loss of total hip BMD in older men. A Prudent dietary pattern may be a potential lifestyle strategy for minimizing bone loss.

INTRODUCTION

This study aimed to identify baseline dietary patterns using factor analysis in a cohort of older men and to evaluate whether the dietary patterns were associated with bone mineral density change (%ΔBMD) at the total hip and femoral neck over time.

METHODS

Participants (n = 4379; mean age 72.9 ± 5.5 years) were from the Osteoporotic Fractures in Men (MrOS) prospective cohort study and had dietary data collected at baseline (March 2000-April 2002) and BMD measured at baseline and Visit 2 (March 2005-May 2006). Dietary intake was assessed with a brief Block food frequency questionnaire (FFQ); factor analysis was used to derive dietary patterns. BMD was measured by dual-energy x-ray absorptiometry (DXA); %ΔBMD was calculated from baseline to Visit 2. We used generalized linear regression to estimate least square (LS) means of %ΔBMD in quartiles of the dietary pattern scores adjusted for potential confounding factors.

RESULTS

Two major dietary patterns were derived: Prudent (abundant in vegetables, salad, and non-fried fish) and Western (rich in hamburger, fries, processed meats, cheese, and sweets/desserts). There was an inverse association between adherence to the Prudent pattern and total hip %ΔBMD (p-trend = 0.028 after adjusting for age and clinical site; p-trend = 0.033 after further adjustment for smoking, calcium supplement use, diabetes, hypertension, and total energy intake). No other consistent associations between dietary patterns and %ΔBMD were observed.

CONCLUSIONS

Greater adherence to a Prudent dietary pattern may attenuate total hip BMD loss (%ΔBMD) in older men.

Rest-activity circadian rhythms and bone mineral density in elderly men

Background

Disrupted rest-activity circadian rhythm (RAR) patterns have been associated with poor health outcomes (i.e. diminished cognitive function, increased risk of dementia and falls). Circadian time cues in bone influence the differentiation of osteoblasts and osteoclasts, and bone turnover markers exhibit circadian variation; relationships between bone outcomes and RAR are emerging areas of research. We evaluated associations between RAR and areal bone mineral density (aBMD) at the total hip and femoral neck in older men from the Osteoporotic Fractures in Men (MrOS) cohort. We hypothesized that weaker RAR patterns would be associated with lower aBMD.

Methods

MrOS is an ongoing prospective cohort study following ambulatory men ≥ 65 years (n = 5994) at 6 U.S. clinics (baseline enrollment 3/2000–4/2002); participants for this analysis are from an ancillary study, Outcomes of Sleep Disorders in Older Men (MrOS Sleep). We included data from men who had technically adequate measures of RAR and aBMD at Sleep Visit 1 (12/2003–3/2005), with repeat aBMD at core Visit 3 (3/2007–3/2009) (n = 2412; mean age at Sleep Visit 1: 75.7 ± 5.2 years). aBMD was measured by dual energy x-ray absorptiometry (DXA). Actigraphs worn on the non-dominant wrist were used to collect circadian activity data over 4.8 ± 0.8 consecutive 24-hour periods. An extension of the traditional cosine curve was used to fit RAR to the activity data [Ancoli-Israel et al., 2003; Marler et al., 2006]. Six RAR parameters were evaluated: acrophase (time of peak activity), amplitude (rhythm strength), mesor (mean of activity fitted curve), pseudo F-statistic (overall circadian rhythmicity of rest and activity), alpha statistic (daytime to nighttime activity ratio), and beta statistic (daytime activity). Associations between RAR and aBMD (Sleep Visit 1), and RAR and ΔaBMD (Sleep Visit 1-Visit 3) were assessed with generalized linear models. Covariates included age, clinic site, physical activity, race, comorbidity, body mass index (BMI), smoking, alcohol, caffeine, beta blocker use, serum 25(OH) vitamin D and urinary melatonin and calcium.

Results

Pseudo F-statistic was significantly associated with total hip aBMD (p-trend = 0.009), femoral neck aBMD (p-trend = 0.007) and total hip ΔaBMD (p-trend = 0.017) in minimally adjusted models but not after multivariate (MV) adjustment. Alpha statistic was significantly associated with femoral neck aBMD (p-trend = 0.029) and femoral neck ΔaBMD (p-trend = 0.019) in minimally adjusted models; significance was retained in the femoral neck ΔaBMD model (p-trend = 0.034) after MV adjustment. There were no consistent, significant associations between the other RAR variables and aBMD or ΔaBMD.

Conclusions

The data demonstrate modest associations between overall circadian rhythmicity of rest and activity (measured by pseudo F-statistic), as well as daytime to nighttime activity ratio (measured by alpha statistic), aBMD and ΔaBMD, but adjustment for covariates related to lifestyle, BMI and comorbidities attenuated most of these associations. These results suggest that RAR patterns are not independently associated with aBMD or four-year ΔaBMD at the total hip or femoral neck in older men, but additional research is needed.

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Disrupted rest-activity circadian rhythm (RAR) undermines health outcomes.

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We modeled RAR patterns and areal bone mineral density (aBMD) in older men.

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Most associations lost significance after multivariate adjustment.

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RAR patterns are not independently associated with aBMD or ΔaBMD in older men.

The role of a dairy fraction rich in milk fat globule membrane in the suppression of postprandial inflammatory markers and bone turnover in obese and overweight adults: an exploratory study

Background

Inflammation is associated with increased bone resorption; the role of inflammation in postprandial bone turnover has not been explored. Consumption of milk fat globule membrane (MFGM) reduces inflammation in animal models. This study aimed to measure postprandial changes in bone turnover after intake of high saturated fat test meals, with- and without the anti-inflammatory ingredient MFGM.

Methods

Subjects (n = 36 adults) were obese (BMI 30–39.9 kg/m²) or overweight (BMI 25–29.9 kg/m²) with two traits of Metabolic Syndrome. Subjects consumed a different test meal on four occasions at random; blood draws were taken at baseline and 1, 3, and 6 h postprandial. Test meals included whipping cream (WC), WC + MFGM, palm oil (PO) and PO + MFGM. Biomarkers of bone turnover and inflammation were analyzed from all four time points.

Results

Test meal (treatment) by time interactions were significant for bone resorption marker C-telopeptide of type 1 collagen (CTX) (p < 0.0001) and inflammatory marker interleukin 10 (IL-10) (p = 0.012). Significant differences in overall postprandial response among test meals were found for CTX and soluble intercellular adhesion molecule (sICAM), with the greatest overall postprandial suppression of CTX occurring in meals containing MFGM. However, test meal by MFGM interactions were non- significant for bone and inflammatory markers. Correlations between CTX and inflammatory markers were non-significant.

Conclusion

This exploratory analysis advances the study of postprandial suppression of bone turnover by demonstrating differing effects of high SFA meals that contained MFGM; however MFGM alone did not directly moderate the difference in postprandial CTX response among test meals in this analysis. These observations may be useful for identifying foods and ingredients which maximize the suppression of bone resorption, and for generating hypotheses to test in future studies examining the role of inflammation in postprandial bone turnover.

Trial registration

Clinicaltrials.gov NCT01811329. Registered 11 March 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-017-0189-z) contains supplementary material, which is available to authorized users.

Rest-activity patterns and falls and fractures in older men

Dysregulated rest-activity rhythm (RAR) patterns have been associated with several health conditions in older adults. This study showed that later acrophase was associated with a modestly greater risk of falls but not fractures in elderly men. Associations between dysregulated RAR patterns and osteoporosis risk warrant further investigation.

PURPOSE

The purpose of this study was to investigate the relationship between rest-activity rhythm (RAR) patterns and risk of falls/fractures in older men. We hypothesized that dysregulated RAR would be associated with incident falls/fractures.

METHODS

We used wrist-worn actigraphy to measure RAR over 4.8 ± 0.8 24-h periods in men (≥67 years) enrolled in the multicenter Outcomes of Sleep Disorders in Men (MrOS Sleep) Study (n = 3001). Men were contacted every 4 months to report occurrence of falls/fractures. RAR parameters included amplitude (difference between peak and nadir activity in counts/minute), mesor (activity counts/minute), acrophase (time of day of peak activity), and pseudo-F statistic (rhythm robustness) and were evaluated as continuous variables with associations reported per SD increase/decrease in models adjusted for confounders. Logistic regression was used to estimate the likelihood (odds ratio, OR) of recurrent falls in the year after the visit. Proportional hazards models were used to estimate the risk (hazard ratio, HR) of fractures.

RESULTS

One year after the visit, 417 men (14%) had recurrent (≥2) falls. Later acrophase (OR 1.18, 95% CI 1.06-1.32) was associated with a modestly greater likelihood of falls. In 8.6 years (SD 2.6 years) of >97% complete follow-up, 256 men (8.53%) had a major osteoporotic fracture, 85 (2.8%) had a clinical spine fracture, and 110 (3.7%) had a hip fracture. No consistent, significant associations were observed between RAR patterns and fractures.

CONCLUSIONS

Later acrophase was associated with a modestly greater risk of falls; this association did not translate into a higher fracture risk in this cohort of elderly men.

Is bone equally responsive to calcium and vitamin D intake from food vs. supplements? Use of (41)calcium tracer kinetic model

Background

Few interventions directly compare equivalent calcium and vitamin D from dairy vs. supplements on the same bone outcomes. The radioisotope calcium-41 (⁴¹Ca) holds promise as a tracer method to directly measure changes in bone resorption with differing dietary interventions.

Objective

Using ⁴¹Ca tracer methodology, determine if 4 servings/day of dairy foods results in greater ⁴¹Ca retention than an equivalent amount of calcium and vitamin D from supplements. Secondary objective was to evaluate the time course for the change in ⁴¹Ca retention.

Methods

In this crossover trial, postmenopausal women (n = 12) were dosed orally with 100 nCi of ⁴¹Ca and after a 180 day equilibration period received dairy (4 servings/day of milk or yogurt; ~ 1300 mg calcium, 400 IU cholecalciferol (vitamin D₃/day)) or supplement treatments (1200 mg calcium carbonate/day and 400 IU vitamin D₃/day) in random order. Treatments lasted 6 weeks separated by a 6 week washout (WO). Calcium was extracted from weekly 24 h urine collections; accelerator mass spectrometry (AMS) was used to determine the ^41/40Ca ratio. Primary outcome was change in ^41/40Ca excretion. Secondary outcome was the time course for change in ⁴¹Ca excretion during intervention and WO periods.

Results

The ^41/40Ca ratio decreased significantly over time during both treatments; there was no difference between treatments. Both treatments demonstrated a significant retention of ⁴¹Ca within 1–2 weeks (p = 0.0007 and p < 0.001 for dairy and supplements, respectively). WO demonstrated a significant decrease (p = 0.0024) in ⁴¹Ca retention within 1–2 weeks, back to pre-intervention levels.

Conclusion

These data demonstrate that urinary ⁴¹Ca retention is increased with an increase in calcium and vitamin D intake regardless of the source of calcium, and the increased retention occurs within 1–2 weeks.

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Investigated, using ⁴¹Ca tracer, whether bone response to calcium and vitamin D differed based on the source of nutrients, foods vs. supplements.

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There was no difference in the bone response by treatment group.

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Both dairy foods and supplements resulted in reduce ⁴¹Ca excretion in urine.

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Reduction in ⁴¹Ca excretion occurred with 2 weeks of initiating the interventions.

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Removal of interventions resulted in 41Ca excretion returning to pre-intervention levels

Addition of a dairy fraction rich in milk fat globule membrane to a high-saturated fat meal reduces the postprandial insulinaemic and inflammatory response in overweight and obese adults

Meals high in SFA, particularly palmitate, are associated with postprandial inflammation and insulin resistance. Milk fat globule membrane (MFGM) has anti-inflammatory properties that may attenuate the negative effects of SFA-rich meals. Our objective was to examine the postprandial metabolic and inflammatory response to a high-fat meal composed of palm oil (PO) compared with PO with an added dairy fraction rich in MFGM (PO+MFGM) in overweight and obese men and women (n 36) in a randomised, double-blinded, cross-over trial. Participants consumed two isoenergetic high-fat meals composed of a smoothie enriched with PO with v. without a cream-derived complex milk lipid fraction ( dairy fraction rich in MFGM) separated by a washout of 1-2 weeks. Serum cytokines, adhesion molecules, cortisol and markers of inflammation were measured at fasting, and at 1, 3 and 6 h postprandially. Glucose, insulin and lipid profiles were analysed in plasma. Consumption of the PO + MFGM v. PO meal resulted in lower total cholesterol (P = 0·021), LDL-cholesterol (P = 0·046), soluble intracellular adhesion molecule (P = 0·005) and insulin (P = 0·005) incremental AUC, and increased IL-10 (P = 0·013). Individuals with high baseline C-reactive protein (CRP) concentrations (≥3 mg/l, n 17) had higher (P = 0·030) insulin at 1 h after the PO meal than individuals with CRP concentrations <3 mg/l (n 19). The addition of MFGM attenuated this difference between CRP groups. The addition of a dairy fraction rich in MFGM attenuated the negative effects of a high-SFA meal by reducing postprandial cholesterol, inflammatory markers and insulin response in overweight and obese individuals, particularly in those with elevated CRP.

Lamina propria lymphocytes, not macrophages, express CCR5 and CXCR4 and are the likely target cell for human immunodeficiency virus type 1 in the intestinal mucosa

Most human immunodeficiency virus type 1 (HIV-1) infections are acquired via mucosal surfaces, and transmitted viruses are nearly always macrophage-tropic, suggesting that mucosal macrophages participate in early HIV-1 infection. Mucosal lymphocytes isolated from normal human intestine expressed CD4 (14,530+/-7970 antibody-binding sites [ABSs]/cell), CCR5 (2730+/-1524 ABSs/cell), and CXCR4 (2507+/-1840 ABSs/cell), but intestinal macrophages, which also expressed CD4 (2959+/-2695 ABSs/cell), displayed no detectable CCR5 or CXCR4 ABS. The absence of CCR5 on intestinal macrophages was not due to expression of the Delta32 deletion allele because matched-blood monocytes expressed CCR5. CCR5(+)CXCR4(+) intestinal lymphocytes supported both R5 (BaL) and X4 (IIIB) HIV-1 replication, whereas the CCR5(-)CXCR4(-) macrophages were not permissive to either isolate or other laboratory isolates (ADA and DJV) and primary isolates (MDR 24 and JOEL). In the intestinal mucosa, lymphocytes, not macrophages, are the likely target cell for R5 (and X4) HIV-1 and are the major source of HIV-1 production during early infection.

Biological parameters of HIV-1 infection in primary intestinal lymphocytes and macrophages

Mucosal surfaces are the portal of entry for most HIV-1 infections and play an important role in disease pathogenesis. To characterize the biological parameters of HIV-1 infection in mucosal cells, we used purified lamina propria lymphocytes and macrophages from normal human small intestine to determine the distribution of the HIV-1 receptor and coreceptors on intestinal mononuclear cells and the permissiveness of these cells to HIV-1 infection. Lamina propria lymphocytes expressed CD4, CCR5, and CXCR4. In contrast, lamina propria macrophages expressed CD4 but not CCR5 or CXCR4. Intestinal lymphocytes supported replication by R5 and X4 isolates of HIV-1, but lamina propria macrophages were permissive to neither. RANTES, macrophage inflammatory protein-1alpha (MIP-1alpha), and MIP-1beta inhibited infection of intestinal lymphocytes by BaL, indicating that R5 infection of the intestinal lymphocytes was mediated by CCR5. Thus, resident lamina propria lymphocytes, not macrophages, are the target mononuclear cell for HIV-1 infection in the intestinal mucosa during early HIV-1 infection.

Retinyl substituted-benzyl ethers. Inhibition of mammary carcinogenesis by retinyl 3,4,5-trimethoxybenzyl ether (RTMBE)

Recently, we reported that retinyl 2-propynyl ether (RPE) inhibits MNU-induced mammary cancer in rats and is less toxic than RME and retinyl acetate. The preparation and biological investigations of retinyl ethers have now been extended to retinyl substituted-benzyl ethers, some of which bind to cellular retinol-binding protein. In long-term (160-180 days) experiments, retinyl 3,4,5-trimethoxybenzyl ether (RTMBE) has been shown to be active against MNU-induced mammary cancer in Sprague-Dawley rats. In effectiveness, RTMBE is comparable, at least, to retinyl acetate; but, unlike retinyl acetate, RTMBE is comparatively non-toxic to rats and mice, is not converted enzymatically to retinol, and does not cause significant increases in retinyl palmitate concentrations in the liver. RTMBE reaches high concentrations in mammary tissue. Two of the four RTMBE congeners that were evaluated in 90 day studies were moderately effective in inhibiting mammary carcinogenesis.

Nurses' responses to people with schizophrenia

General nurses, psychiatric nurses and lay people were investigated to identify differences between their personal standards concerning how they should respond, and beliefs about how they actually would respond, towards the target group, 'people with schizophrenia', in each of three response domains (thinking, feeling and behaving). Significant differences were identified between the response types and between the different response domains. Significant interaction effects were also identified based on participants professional status in nursing. It is argued that the results support Devine's (1989) theory concerning the automatic activation of stereotypes and their controlled inhibition in favour of different personal beliefs. It is also argued that professional specialization in psychiatric nursing facilitates this process in relation to the target group.

Acute and chronic administration of ibogaine to the rat results in astrogliosis that is not confined to the cerebellar vermis

Acute administration of high doses of ibogaine (IBG) to the male rat results in degeneration of Purkinje cells and reactive gliosis in the cerebellar vermis. We examined whether acute and chronic administration of IBG to male and female rats results in gliosis as determined by quantification of the astroglial intermediate filament protein, glial fibrillary acidic protein (GFAP). After acute administration of IBG, rats of both sexes showed dose-related increases in GFAP that were not confined to the cerebellar vermis. After chronic administration of IBG, female, but not male rats, showed large (as much as 200% of control), dose-related increases in GFAP in hippocampus, olfactory bulbs, brain stem and striatum, but not cerebellum. In hippocampus, the cytoskeletal proteins, neurofilament 68 (NF-68) and beta-tubulin were increased in females treated chronically with IBG, findings consistent with a damage-induced sprouting response. Together, the data indicate that IBG damages areas of the brain outside the cerebellum and that the sites damaged are dependent on sex and dosage regimen.

Murine toxicology and pharmacology of UAB-8, a conformationally constrained analog of retinoic acid

(2E, 4E, 6E)-8-[3'-Ethyl-2'-(1-methylethyl)-2'-cyclohexen-1'-ylidene] -3, 7-dimethyl-2,4,6-octatrienoic acid (UAB-8) has potent activity in preventing papillomas on the skin of mice similar to that determined in a previous study for the homolog containing one less carbon atom. To evaluate the toxicological profile for UAB-8, relative to all-trans-retinoic acid (RA), female mice were dosed by oral gavage for 29 days with amounts of 0.05, 0.1, or 0.2 mmol/kg/day. For the two compounds, the effects on body weights were similar. Mice dosed with UAB-8, however, had a lower incidence of clinical signs of toxicity (alopecia, scaly skin, and limping). At necropsy, bone fractures, skin abnormalities, and splenomegaly were observed in some mice dosed with RA but not in any dosed with UAB-8. Lymph node hyperplasia was noted in some mice dosed with either dose of RA but only in those dosed with the highest dose of UAB-8. All dose levels of RA produced microscopic lesions in the bones of mice; only the highest dose of UAB-8 had this effect. RA and UAB-8 had similar effects on chondrogenesis in cultures of cells from mouse limb buds, an indication of comparable teratogenic effects. For mice dosed i.v. (10 mg/kg), there was a saturated phase of elimination of RA from plasma (Km = 0.61 microgram/ml and Vmax = 2572 micrograms/hr); no such phase was noted when UAB-8 was administered. UAB-8 had values for t1/2 alpha and t1/2 beta of 0.47 and 17.1 hr, respectively. Relative to RA, UAB-8 has a favorable toxicological profile and different pharmacokinetics.

A conformationally defined 6-s-trans-retinoic acid isomer: synthesis, chemopreventive activity, and toxicity

A conformationally defined retinoic acid analog (1) which contains a dimethylene bridge to maintain the 6-s-trans orientation for two terminal double bonds in the polyene chain was synthesized. A Reformatsky reaction was utilized to extend the polyene chain of the starting enone, which provided exclusively the 9Z-configuration for the intermediate aldehyde. A Horners-Emmons condensation with this aldehyde then produced retinoic acid analogs with both 9Z- and 9Z,13Z-configurations. An I2-catalyzed isomerization of the intermediate 9Z-aldehyde yielded the all-E-aldehyde, which was olefinated as above to yield the (all-E)- and (13Z)-retinoic acid analogs of 1. Each configurational isomer of 1 was evaluated for its ability to inhibit the binding of retinoic acid to CRABP (chick skin) and to inhibit the chemical induction of ornithine decarboxylase in mouse skin. In each assay (all-E)-1 was the most active isomer, and this activity was comparable to or better than that for (all-E)-retinoic acid. (all-E)-1 and (13Z)-1 were both shown to be equally effective as (13Z)-retinoic acid in suppressing the proliferation of human sebaceous cells in vitro. (all-E)-1 was further evaluated for its ability to prevent the induction of mouse skin papillomas and to induce signs of vitamin A toxicity in mice. The cancer chemopreventive activity of (all-E)-1 was comparable to that of (all-E)-retinoic acid, and the toxicity was comparable to or slightly better than that of the natural vitamin.

Cancer chemopreventive 3-substituted-4-oxoretinoic acids

The introduction of substituents at position 3 of methyl 4-oxoretinoate can be effected in good yields by alkylating the lithium dienolate. A second substituent can be introduced also, but the resulting 3,3-disubstituted-4-oxoretinoates were isolated in lower yields. Evidence was obtained for a slower rate of alkylation at the alpha-position (carbon 14) of the ester group. Some of these 4-oxoretinoic acid analogues showed high activity in assays in vivo for the inhibition of ornithine decarboxylase activity and carcinogen-induced papillomas in mouse skin.

Identification of a 43-kilodalton human T lymphocyte membrane protein as a receptor for pertussis toxin

Pertussis toxin (PTx), an exotoxin of Bordetella pertussis has been used as a molecular probe to study stimulus-response coupling in a wide variety of cells. We have previously shown that PTx activates the same signal transduction pathways as Ag or mAb directed against the CD3-T cell Ag receptor complex in human T cells. Because the EC50 for mitogenic stimulation by PTx was 1.7 nM, we suspected that the toxin was specifically interacting with a membrane protein or receptor. We have used both chemical cross-linking and Western blotting techniques to demonstrate that PTx shows specific binding to a 43 kDa-membrane protein on cells that respond to PTx by rapid second messenger production. The PTx receptor can be detected in both the E6-1 Jurkat cell line and a CD3-TCR-negative Jurkat line, demonstrating that it is not coordinately expressed with the Ag receptor complex. The 43 kDa-protein is also found in the HPB-ALL human T cell line and PBL, but not in a murine T cell hybridoma or human neutrophils, both of which are unresponsive to PTx activation. These data suggest that the biochemical basis for the mitogenic activity of PTx may lie in its binding to a specific membrane receptor that is capable of transmitting an activation signal.

Identification of a 43-kilodalton human T lymphocyte membrane protein as a receptor for pertussis toxin

Pertussis toxin (PTx), an exotoxin of Bordetella pertussis has been used as a molecular probe to study stimulus-response coupling in a wide variety of cells. We have previously shown that PTx activates the same signal transduction pathways as Ag or mAb directed against the CD3-T cell Ag receptor complex in human T cells. Because the EC50 for mitogenic stimulation by PTx was 1.7 nM, we suspected that the toxin was specifically interacting with a membrane protein or receptor. We have used both chemical cross-linking and Western blotting techniques to demonstrate that PTx shows specific binding to a 43 kDa-membrane protein on cells that respond to PTx by rapid second messenger production. The PTx receptor can be detected in both the E6-1 Jurkat cell line and a CD3-TCR-negative Jurkat line, demonstrating that it is not coordinately expressed with the Ag receptor complex. The 43 kDa-protein is also found in the HPB-ALL human T cell line and PBL, but not in a murine T cell hybridoma or human neutrophils, both of which are unresponsive to PTx activation. These data suggest that the biochemical basis for the mitogenic activity of PTx may lie in its binding to a specific membrane receptor that is capable of transmitting an activation signal.

Arachidonic acid turnover in peritoneal macrophages is altered in endotoxin-tolerant rats

Peritoneal macrophages from endotoxin-tolerant rats have been found to exhibit depressed metabolism of arachidonic acid (AA) to prostaglandins and thromboxane in response to endotoxin. The effect of endotoxin tolerance on AA turnover in peritoneal macrophages was investigated by measuring [14C]AA incorporation and release from membrane phospholipids. Endotoxin tolerance did not affect the amount of [14C]AA incorporated into macrophages (30 min-24 h). However, the temporal incorporation of [14C]AA into individual phospholipid pools (15 min-24 h) was altered. In endotoxin-tolerant macrophages, [14C]AA incorporation into phosphatidylcholine (PC) (2, 4, 24 h) and phosphatidylethanolamine (PE) (8 h) was increased, while the incorporation into phosphatidylserine (PS) (2-24 h) was reduced (P less than 0.005) compared to control macrophages. There was no change in [14C]AA incorporation into phosphatidylinositol (PI). Following 2 or 24 h of incorporation of [14C]AA, macrophages were incubated (3 h) with endotoxin (50 micrograms/ml) or A23187 (1 microM), and [14C]AA release was measured. Endotoxin-tolerant macrophages released decreased (P less than 0.05) amounts of [14C]AA in response to both endotoxin and the calcium ionophore A23187 compared to controls. Control macrophages in response to endotoxin released [14C]AA from PC, PI and PE. In contrast, tolerant cells released [14C]AA only from PC (P less than 0.05). A23187 released [14C]AA from all four pools in the control cells, but only from PC and PE in the tolerant cells. These data demonstrate that endotoxin tolerance alters the uptake and release of AA from specific macrophage phospholipid pools. These results suggest that changes in AA turnover and/or storage are associated with endotoxin tolerance.

The effect of dietary supplementation with n-3 polyunsaturated fatty acids on the synthesis of interleukin-1 and tumor necrosis factor by mononuclear cells

We examined whether the synthesis of interleukin-1 or tumor necrosis factor, two cytokines with potent inflammatory activities, is influenced by dietary supplementation with n-3 fatty acids. Nine healthy volunteers added 18 g of fish-oil concentrate per day to their normal Western diet for six weeks. We used a radioimmunoassay to measure interleukin-1 (IL-1 beta and IL-1 alpha) and tumor necrosis factor produced in vitro by stimulated peripheral-blood mononuclear cells. With endotoxin as a stimulus, the synthesis of IL-1 beta was suppressed from 7.4 +/- 0.9 ng per milliliter at base line to 4.2 +/- 0.5 ng per milliliter after six weeks of supplementation (43 percent decrease; P = 0.048). Ten weeks after the end of n-3 supplementation, we observed a further decrease to 2.9 +/- 0.5 ng per milliliter (61 percent decrease; P = 0.005). The production of IL-1 alpha and tumor necrosis factor responded in a similar manner. Twenty weeks after the end of supplementation, the production of IL-1 beta, IL-1 alpha, and tumor necrosis factor had returned to the presupplement level. The decreased production of interleukin-1 and tumor necrosis factor was accompanied by a decreased ratio of arachidonic acid to eicosapentaenoic acid in the membrane phospholipids of mononuclear cells. We conclude that the synthesis of IL-1 beta, IL-1 alpha, and tumor necrosis factor can be suppressed by dietary supplementation with long-chain n-3 fatty acids. The reported antiinflammatory effect of these n-3 fatty acids may be mediated in part by their inhibitory effect on the production of interleukin-1 and tumor necrosis factor.

Selective enhancement of thromboxane in macrophages and kidneys in cyclosporine-induced nephrotoxicity. Dietary protection by fish oil

Cyclosporine (CsA) associated renal dysfunction is related in part to renal vasoconstriction. To identify the role of cyclooxygenase metabolites in the induction of vasoconstriction, we analyzed the effect of CsA on the synthesis of thromboxane (TxA2) prostacyclin (PGI2) and prostaglandin E2 (PGE2) in the kidney and peritoneal macrophages. Groups of rats were pair-fed diets enriched with 20% fish oil (FO) or corn oil (CO) for 4 weeks and then were injected with CsA 12.5 mg/kg/day i.p. for 2 weeks. CsA induced the synthesis of TxA2 and modestly reduced PGE2 and PGI2 in renal cortex and peritoneal macrophages. Feeding rats a diet enriched in FO containing omega-3 fatty acids as compared with CO without these fatty acids suppressed the increase in TxA2 and decreased the vasodilators PGE2 and PGI2 in the kidney and peritoneal macrophages, while modifying the decrease in the glomerular filtration rate and vacuolization in proximal convoluted tubules characteristic of rodent CsA-associated nephrotoxicity. Thus, CsA-initiated renal vasoconstriction is related to an increase in the vasoconstrictive Tx molecule and the reduction in vasodilator metabolites. Intrarenal macrophages represent a likely source of this Tx production. Feeding rats diets containing omega-3 fatty acids, known to be competitive inhibitors of cyclooxygenase metabolites, prevents CsA from selectively increasing TxA2 and preserves renal function.

Differential alteration of lipoxygenase and cyclooxygenase metabolism by rat peritoneal macrophages induced by endotoxin tolerance

Altered macrophage arachidonic acid metabolism may play a role in endotoxic shock and the phenomenon of endotoxin tolerance induced by repeated injections of endotoxin. Studies were initiated to characterize both lipoxygenase and cyclooxygenase metabolite formation by endotoxin tolerant and non-tolerant macrophages in response to 4 different stimuli, i.e. endotoxin, glucan, zymosan, and the calcium ionophore A23187. In contrast to previous reports of decreased prostaglandin synthesis by tolerant macrophages, A23187-stimulated immunoreactive (i) leukotriene (LT)C4/D4 and prostaglandin (PG)E2 production by tolerant cells was greater than that by non-tolerant controls (p less than 0.001). However, A23187-stimulated i-6-keto-PGF1 alpha levels were lower in tolerant macrophages compared to controls. Stimulation of prostaglandin and thromboxane (Tx)B2 synthesis by endotoxin or glucan was significantly less in tolerant macrophages compared to controls (p less than 0.05). iLTC4/D4 production was not significantly stimulated by endotoxin or glucan, but was stimulated by zymosan in the non-tolerant cells. Synthesis of iLTB4 by control macrophages was stimulated by endotoxin (p less than 0.01). These results demonstrate that arachidonic acid metabolism via the lipoxygenase and cyclooxygenase pathways in macrophages is differentially altered by endotoxin tolerance.