Iron metabolism is prospectively associated with insulin resistance and glucose intolerance over a 7-year follow-up period: the CODAM study

OBJECTIVES

Several markers of iron metabolism have been associated with insulin resistance (IR) and type 2 diabetes mellitus in cross-sectional studies. However, prospective data on these associations are scarce, and it is currently unclear in which tissues iron metabolism may contribute to IR. Therefore, we investigated whether markers of iron metabolism were associated with IR in muscle, liver, and adipocytes, and with glucose intolerance over a 7-year follow-up period.

DESIGN AND METHODS

Serum ferritin, transferrin, total iron, non-transferrin-bound iron, and transferrin saturation were determined at baseline of a prospective cohort study in 509 individuals (60 % men, age 59 ± 6.9 years, body mass index 28.5 ± 4.3). Both at baseline and after a 7-year follow-up (n = 386), measures of glucose, insulin (during glucose tolerance tests), and non-esterified fatty acids were obtained. Using generalized estimating equations, we investigated associations between baseline iron markers and indices of muscle, liver, and adipocyte insulin resistance (adipocyte IR), as well as glucose intolerance, over the 7-year period.

RESULTS

Over a 7-year period, baseline serum ferritin (per 10 μg/L increase) was positively associated with homeostasis model assessment insulin resistance (HOMA2-IR) [β = 0.77 % (95 % CI 0.50-1.03)], hepatic insulin resistance (hepatic IR) [β = 0.39 % (0.23-0.55)], adipocyte IR [β = 1.00 % (0.65-1.35)], and AUCglucose [β = 0.32 % (0.18-0.46)] after adjustment for several covariates, including inflammatory markers (all p < 0.001). Similarly, serum transferrin (per 0.1 g/L) was associated with HOMA2-IR [β = 2.66 % (1.55-3.78)], hepatic IR [β = 1.16 % (0.47-1.85)], adipocyte IR [β = 3.75 % (2.27-5.25)], and AUCglucose [β = 1.35 % (0.74-1.96)] over 7 years.

CONCLUSIONS

Iron metabolism and related factors may contribute to IR in muscle, liver, and adipocytes, eventually leading to impaired glucose metabolism and hyperglycaemia.

Broadband light trapping in thin film solar cells with self-organized plasmonic nano-colloids

The intense light scattered from metal nanoparticles sustaining surface plasmons makes them attractive for light trapping in photovoltaic applications. However, a strong resonant response from nanoparticle ensembles can only be obtained if the particles have monodisperse physical properties. Presently, the chemical synthesis of colloidal nanoparticles is the method that produces the highest monodispersion in geometry and material quality, with the added benefits of being low-temperature, low-cost, easily scalable and of allowing control of the surface coverage of the deposited particles. In this paper, novel plasmonic back-reflector structures were developed using spherical gold colloids with appropriate dimensions for pronounced far-field scattering. The plasmonic back reflectors are incorporated in the rear contact of thin film n-i-p nanocrystalline silicon solar cells to boost their photocurrent generation via optical path length enhancement inside the silicon layer. The quantum efficiency spectra of the devices revealed a remarkable broadband enhancement, resulting from both light scattering from the metal nanoparticles and improved light incoupling caused by the hemispherical corrugations at the cells' front surface formed from the deposition of material over the spherically shaped colloids.

Autophagy and inflammasome interplay

Inflammation is a defensive response of the organism to manage harmful stimuli sensed by innate immune cells. The signal alarm is triggered by the recognition of pathogen-associated molecular patterns, such as microbial components, or host-derived damage-associated molecular patterns (DAMPs), namely high-mobility group box 1 protein (HMGB1) and purine metabolites, through a set of highly conserved receptors in immune cells termed pattern recognition receptors. Among these receptors, membrane-associated toll-like receptors (TLRs) and cytosolic nucleotide binding and oligomerization domain (nod)-like receptors (NLRs) assume particular relevance in the inflammatory process. Once activated, NLRs induce the assembly of multiprotein complexes called inflammasomes, leading to production of proinflammatory cytokines (e.g., interleukin-1) and induction of inflammatory cell death (pyroptosis) through the activation of caspase-1. Although these processes intend to protect the body from insults, prolonged or exacerbated inflammatory responses associated with inflammasome activation are related to a growing number of diseases. Recently, inflammasome activation and autophagy were shown to be linked and to mutually influence each other. Therefore, we aim, in this review, to discuss the recent evidences concerning the cross talk between autophagy and inflammasome activation and its potential roles in disease progression.

A healthy diet is associated with less endothelial dysfunction and less low-grade inflammation over a 7-year period in adults at risk of cardiovascular disease

BACKGROUND

A healthy diet rich in fish, fruit, and vegetables, but moderate in alcohol and low in dairy products and meat, has been associated with a lower rate of incident cardiovascular disease (CVD). The underlying mechanisms, however, remain unclear. Endothelial dysfunction and low-grade inflammation play important roles in CVD. A healthy diet might modify these phenomena.

OBJECTIVE

We investigated the associations between the above food groups and overall biomarker scores of endothelial dysfunction and low-grade inflammation in a 7-y longitudinal study.

METHODS

Using longitudinal data from 557 participants at increased CVD risk from the CODAM (Cohort on Diabetes and Atherosclerosis Maastricht) Study, we assessed diet intake by food-frequency questionnaire and measured plasma biomarkers of endothelial dysfunction [von Willebrand factor, soluble vascular cell adhesion molecule 1, soluble endothelial selectin, soluble thrombomodulin, soluble intercellular adhesion molecule 1 (sICAM-1)] and low-grade inflammation [C-reactive protein, serum amyloid A, interleukin (IL)-6, IL-8, tumor necrosis factor α, and sICAM-1]. At baseline, participants were aged 59.6 ± 6.9 y. Measurements were performed then and after 7 y. Biomarkers were combined into overall scores (sum of z scores; higher scores indicating worse function). Longitudinal data were analyzed with generalized estimating equations and adjusted for sex, age, glucose metabolism, energy intake, body mass index, physical activity, alcohol consumption, and smoking.

RESULTS

Higher consumption of fish (per 100 g/wk), but not total consumption of vegetables, fruit, alcohol-containing beverages, dairy products, or meat, was associated with a lower overall endothelial dysfunction score over 7 y (β: -0.027; 95% CI: -0.051, -0.004). No associations were observed with the overall low-grade inflammation score. Further food component analyses indicated that consumption of more lean fish (per 100 g/wk) and raw vegetables (per 100 g/d), and fewer high-fat dairy products (per 100 g/d) was associated with less endothelial dysfunction [(β: -0.038; 95% CI: -0.072, -0.005), (β: -0.095; 95% CI: -0.191, 0.000), and (β: -0.070; 95% CI: -0.131, -0.009), respectively]. Consumption of more fresh fruit (per 100 g/d), wine (per 100 mL/wk), and poultry (per 100 g/d), and fewer high-fat dairy products (per 100 g/d) was associated with less low-grade inflammation [(β: -0.074; 95% CI: -0.133, -0.015), (β:-0.006; 95% CI: -0.013, 0.001), (β:-0.247; 95% CI: -0.479, -0.014), and (β:-0.100; 95% CI: -0.182, -0.019), respectively].

CONCLUSION

These data suggest that the dietary modification of endothelial dysfunction and low-grade inflammation, processes that are important in atherothrombosis, is possible.

A control systems approach to quantify wall shear stress normalization by flow-mediated dilation in the brachial artery

Flow-mediated dilation is aimed at normalization of local wall shear stress under varying blood flow conditions. Blood flow velocity and vessel diameter are continuous and opposing influences that modulate wall shear stress. We derived an index FMDv to quantify wall shear stress normalization performance by flow-mediated dilation in the brachial artery. In 22 fasting presumed healthy men, we first assessed intra- and inter-session reproducibilities of two indices pFMDv and mFMDv, which consider the relative peak and relative mean hyperemic change in flow velocity, respectively. Second, utilizing oral glucose loading, we evaluated the tracking performance of both FMDv indices, in comparison with existing indices [i.e., the relative peak diameter increase (%FMD), the peak to baseline diameter ratio (Dpeak/Dbase), and the relative peak diameter increase normalized to the full area under the curve of blood flow velocity with hyperemia (FMD/shearAUC) or with area integrated to peak hyperemia (FMD/shearAUC_peak)]. Inter-session and intra-session reproducibilities for pFMDv, mFMDv and %FMD were comparable (intra-class correlation coefficients within 0.521-0.677 range). Both pFMDv and mFMDv showed more clearly a reduction after glucose loading (reduction of ~45%, p≤0.001) than the other indices (% given are relative reductions): %FMD (~11%, p≥0.074); Dpeak/Dbase (~11%, p≥0.074); FMD/shearAUC_peak (~20%, p≥0.016) and FMD/shearAUC (~38%, p≤0.038). Further analysis indicated that wall shear stress normalization under normal (fasting) conditions is already far from ideal (FMDv << 1), which (therefore) does not materially change with glucose loading. Our approach might be useful in intervention studies to detect intrinsic changes in shear stress normalization performance in conduit arteries.

Persistence at 12 months with denosumab in postmenopausal women with osteoporosis: interim results from a prospective observational study

To determine persistence with subcutaneous denosumab every 6 months in women being treated for osteoporosis, we conducted a single-arm prospective, observational study in the United States and Canada. Among 935 patients enrolled, 12-month persistence was 82%, with 66 patients (7%) reporting serious adverse events and 19 patients (2%) reporting fractures.

INTRODUCTION

Increased persistence with osteoporosis therapy is associated with reduced fracture risk. Denosumab reduced fracture risk in clinical trials; persistence in community settings is undetermined. This study evaluates persistence with denosumab in community practice in the United States (US) and Canada.

METHODS

In a 24-month multicenter, prospective, single-arm, observational study, women being treated for osteoporosis were enrolled ≤4 weeks after the first subcutaneous injection of denosumab. For this 12-month prespecified interim analysis, endpoints include persistence (one injection at study entry and another within 6 months + 8 weeks), attributes associated with persistence (univariate analysis), and serious adverse events (SAEs).

RESULTS

Among 935 patients (mean age 71 years), mean baseline T-scores were -2.18 (femoral neck) and -2.00 (lumbar spine); 50% of patients had experienced osteoporotic fracture(s). At 12 months, 82 % of patients were persistent with denosumab. Baseline factors significantly (p < 0.05) associated with higher persistence included use of osteoporosis medications >5 years previously, lumbar spine T-score > -2.5, and treatment by female physicians (US). Lower persistence was associated (p < 0.05) with psychiatric diagnoses including depression, southern US residence, being divorced, separated, or widowed (US), and prior hip fracture (Canada). SAEs were reported in 66 patients (7%); no SAEs of osteonecrosis of the jaw, atypical femoral fracture, fracture healing complications, hypocalcemia, eczema, or hypersensitivity were reported. Nineteen patients (2%) reported osteoporotic fractures.

CONCLUSIONS

The 12-month persistence observed in this single-arm open-label study of US and Canadian community practice extends the evidence regarding denosumab's potential role in reducing fracture risk in postmenopausal women with osteoporosis.

Oxidative stress-dependent activation of the eIF2α–ATF4 unfolded protein response branch by skin sensitizer 1-fluoro-2,4-dinitrobenzene modulates dendritic-like cell maturation and inflammatory status in a biphasic manner [corrected]

The pathogenesis of allergic contact dermatitis, the most common manifestation of immunotoxicity in humans, is intimately connected to hapten-induced maturation of dendritic cells (DC). The molecular mechanisms driving this maturational program are not completely known; however, initial danger signals such as the generation of reactive oxygen species (ROS) were shown to play a critical role. Recent evidence linking ROS production, endoplasmic reticulum (ER) stress, and the pathogenesis of several inflammatory diseases led us to analyze, in the present work, the ability of the skin sensitizer 1-fluoro-2,4-dinitrobenzene (DNFB) to evoke ER stress in DC-like THP-1 cells and the concomitant consequences to their immunobiology. We found that DNFB triggers a ROS-dependent activation of the PERK-eIFα-ATF4 unfolded protein response (UPR) branch conferring cytoprotection and modulating the maturation/proinflammatory cell status in a biphasic manner. Early DNFB induction of ATF4 positively modulates autophagy-related genes MAP1LC3B and ATG3 and stabilizes the transcription factor Nrf2, causing a strong induction of the HMOX1-detoxifying gene. Moreover, we observed that in a first phase, DNFB-induced ATF4 upregulates IL8 mRNA levels while blocking CD86, IL1B, IL12B, and CXL10 transcription. Later, following ATF4 decay, HMOX1 and IL8 transcription drastically decrease and CD86, IL1B, and Il12B are upregulated. Overall, our results evidence a connection between sensitizer-induced redox imbalance and the establishment of ER stress in DC-like cells and provide new insights into the role of UPR effectors such as ATF4 to the complex DC maturational program.

Denosumab significantly increases bone mineral density and reduces bone turnover compared with monthly oral ibandronate and risedronate in postmenopausal women who remained at higher risk for fracture despite previous suboptimal treatment with an oral bisphosphonate

Managing osteoporotic patients suboptimally adherent to bisphosphonates (BPs) is difficult. Such patients who remained at higher risk for fracture (≥1 risk factor) were transitioned to denosumab or a monthly oral BP. Denosumab-treated subjects had significantly greater increases in bone mineral density and decreases in bone turnover in this 12-month study.

INTRODUCTION

A clinical need exists to manage patients who are suboptimally adherent to oral BPs and remain at higher risk for fracture. Here, we compare the effects on bone mineral density (BMD) and bone turnover of transitioning such patients to denosumab or monthly oral BP (ibandronate or risedronate).

METHODS

In two previous multicenter, open-label studies, postmenopausal women ≥55 years previously treated with, though suboptimally adherent to, a daily or weekly BP were randomized to denosumab 60 mg subcutaneously every 6 months (N = 852) or oral BP 150 mg monthly (N = 851) for 12 months. In this combined post-hoc analysis, a subset of higher risk subjects was identified, and the percentage changes from baseline in BMD and serum C-telopeptide of type I collagen (sCTX-1) were assessed.

RESULTS

In the overall population, denosumab was associated with greater gains in BMD at 12 months than monthly oral BP at the total hip, femoral neck, and lumbar spine (p < 0.0001 for all). In higher risk subjects, denosumab led to greater gains in BMD than oral BPs at the total hip (2.2 vs 0.8 %), femoral neck (1.8 vs 0.3 %), and lumbar spine (3.7 vs 1.4 %) (p < 0.0001 for all). Denosumab also led to greater decreases in sCTX-1 in the overall population and higher risk subjects at months 1 and 6 (p < 0.0001 for both). Adverse events and serious adverse events were generally similar between treatment groups.

CONCLUSIONS

Transitioning to denosumab was well tolerated and more effective in increasing BMD and reducing bone turnover than cycling to a monthly oral BP treatment in subjects who remained at higher fracture risk despite suboptimal BP treatment.

Complement factor 3 is associated with insulin resistance and with incident type 2 diabetes over a 7-year follow-up period: the CODAM Study

OBJECTIVE

Immune dysregulation can affect insulin resistance (IR) and β-cell function and hence contribute to development of type 2 diabetes mellitus (T2DM). The complement system, as a regulator of immune and inflammatory homeostasis, may be a relevant contributor therein. However, longitudinal studies focusing on complement as a determinant of T2DM and IR are scarce. Therefore, we prospectively investigated the association of plasma complement factor 3 (C3) with (estimates of) IR in muscle, liver, and adipocytes, as well as with glucose tolerance, including incident T2DM.

RESEARCH DESIGN AND METHODS

Fasting C3, nonesterified fatty acids, glucose, and insulin (the latter two during oral glucose tolerance tests) were measured at baseline (n = 545) and after 7 years of follow-up (n = 394) in a prospective cohort study.

RESULTS

Over the 7-year period, C3 levels (per 0.1 g/L) were longitudinally associated with higher homeostasis model assessment of IR (HOMA2-IR; β = 15.2% [95% CI 12.9-17.6]), hepatic IR (β = 6.1% [95% CI 4.7-7.4]), adipocyte IR (β = 16.0% [95% CI 13.0-19.1]), fasting glucose (β = 1.8% [95% CI 1.2-2.4]), 2-h glucose (β = 5.2% [95% CI 3.7-6.7]), and area under the curve for glucose (β = 3.6% [95% CI 2.7-4.6]). In addition, greater changes in C3 (per 0.1 g/L) were associated with greater changes in HOMA2-IR (β = 0.08 [95% CI 0.02-0.15]) and greater changes in hepatic IR (β = 0.87 [95% CI 0.12-1.61]) over 7 years, but not glucose tolerance. Moreover, baseline C3 was associated with the 7-year incidence of T2DM (odds ratio 1.5 [95% CI 1.1-2.0]).

CONCLUSIONS

Changes in C3 were associated with changes in several measures of IR and may reflect progression of metabolic dysregulation, which eventually leads to abnormalities in glucose tolerance and T2DM.

Broadband photocurrent enhancement in a-Si:H solar cells with plasmonic back reflectors

Plasmonic light trapping in thin film silicon solar cells is a promising route to achieve high efficiency with reduced volumes of semiconductor material. In this paper, we study the enhancement in the opto-electronic performance of thin a-Si:H solar cells due to the light scattering effects of plasmonic back reflectors (PBRs), composed of self-assembled silver nanoparticles (NPs), incorporated on the cells' rear contact. The optical properties of the PBRs are investigated according to the morphology of the NPs, which can be tuned by the fabrication parameters. By analyzing sets of solar cells built on distinct PBRs we show that the photocurrent enhancement achieved in the a-Si:H light trapping window (600 - 800 nm) stays in linear relation with the PBRs diffuse reflection. The best-performing PBRs allow a pronounced broadband photocurrent enhancement in the cells which is attributed not only to the plasmon-assisted light scattering from the NPs but also to the front surface texture originated from the conformal growth of the cell material over the particles. As a result, remarkably high values of J(sc) and V(oc) are achieved in comparison to those previously reported in the literature for the same type of devices.

The cross-sectional association between uric acid and atherosclerosis and the role of low-grade inflammation: the CODAM study

OBJECTIVES

The aims of this study were to investigate (i) associations between uric acid and prevalent cardiovascular disease (CVD), ankle-arm blood pressure index (AAIx) and carotid intima-media thickness (CIMT) in the total population and in predefined subgroups according to glucose metabolism status and (ii) the extent to which these associations are explained by low-grade inflammation.

METHODS

Cross-sectional analyses were conducted among 530 individuals [60.6% men, mean age 58.9 years (s.d. 6.9), 52.6% normal glucose metabolism (NGM)] at increased risk of CVD from the Cohort of Diabetes and Atherosclerosis Maastricht study. A low-grade inflammation score was computed by averaging the z-scores of eight inflammation markers [CRP, TNF-α, IL-6, IL-8, serum amyloid A, intercellular adhesion molecule 1 (ICAM-1), ceruloplasmin and haptoglobin].

RESULTS

After adjustment for traditional CVD risk factors, plasma uric acid (per s.d. of 81 μmol/l) was associated with CVD in individuals with NGM [odds ratio (OR) = 1.66, 95% CI 1.06, 2.58] but not with disturbed glucose metabolism (DGM) (OR = 0.81, 95% CI 0.55, 1.19, P interaction = 0.165). Uric acid was associated with CIMT in the total population (β = 0.024, 95% CI 0.007, 0.042) and slightly more strongly in individuals with NGM (β = 0.030, 95% CI 0.006, 0.054) than DGM (β = 0.018, 95% CI -0.009, 0.044, P interaction = 0.443). There was no association between uric acid and AAIx in any group (P interaction = 0.058). Uric acid was associated with low-grade inflammation in the total population (β = 0.074, 95% CI 0.013, 0.134, P interaction = 0.737). Adding low-grade inflammation to the models did not attenuate any of the associations.

CONCLUSION

The associations for uric acid with CIMT, and with CVD in NGM only, were not explained by low-grade inflammation. A difference in the strength of the associations between individuals with NGM and DGM was suggested.

Vaccines and biologics

Patients with autoimmune rheumatic diseases are more susceptible to infectious complications during the course of their disease. The introduction of biologics has been a major achievement in treating these diseases, but an increased risk of infection associated with these therapies has become evident. Some infections can be prevented by vaccination and it is clearly worthwhile considering which immunisations would be sensible and practicable for these patients. To date no formal specific recommendations for patients on biologics have been published. A search was made of Medline (via PubMed) from 1970 to January 2014 to provide results. This review aims to provide a systematic analysis of the data about vaccines and biologics and considers recommendations for vaccination in adult patients with autoimmune rheumatic diseases treated with biologics.

Coccidial dispersion across trans- and cis-Andean antbirds (Passeriformes: Thamnophilidae): Isospora sagittulae (Apicomplexa: Eimeriidae) from nonsympatric hosts

Isospora sagittulae McQuistion and Capparella, 1992 (Protozoa: Apicomplexa: Eimeriidae) is reported from White-throated Antbirds (Gymnopithys salvini (Berlepsch, 1901)) and from Common Scale-backed Antbirds (Willisornis poecilinotus (Cabanis, 1847)), which are thamnophilid birds from the Brazilian Amazon. Its oocysts are ovoidal to ellipsoidal, 28.4 μm × 22.4 μm, with smooth, bilayered wall, 1.1 μm. Micropyle and oocyst residuum are absent, but one to three polar granules are present. Sporocysts are subspherical to ovoidal, 15.0 μm × 12.6 μm. Stieda body thin and flattened and substieda body triangular to round. Sporocyst residuum composed of scattered granules. Sporozoites with refractile body and nucleus. This coccidium was originally described from the Spotted Antbird (Hylophylax naevioides (Lafresnaye, 1847)), a trans-Andean antbird that is not sympatric with G. salvini and W. poecilinotus, which are cis-Andean antbirds from lowland Amazon forest; therefore, this current study presents some assumptions to explain the dispersion of I. sagittulae among antbird species.

Denosumab compared with risedronate in postmenopausal women suboptimally adherent to alendronate therapy: efficacy and safety results from a randomized open-label study

Denosumab has been shown to reduce new vertebral, nonvertebral, and hip fractures in postmenopausal women with osteoporosis. In subjects who were treatment-naïve or previously treated with alendronate, denosumab was associated with greater gains in bone mineral density (BMD) and decreases in bone turnover markers when compared with alendronate-treated subjects. This trial was designed to compare the efficacy and safety of denosumab with risedronate over 12 months in postmenopausal women who transitioned from daily or weekly alendronate treatment and were considered to be suboptimally adherent to therapy. In this randomized, open-label study, postmenopausal women aged ≥55 years received denosumab 60 mg subcutaneously every 6 months or risedronate 150 mg orally every month for 12 months. Endpoints included percentage change from baseline in total hip BMD (primary endpoint), femoral neck, and lumbar spine BMD at month 12, and percentage change from baseline in sCTX-1 at months 1 and 6. Safety was also assessed. A total of 870 subjects were randomized (435, risedronate; 435, denosumab) who had a mean (SD) age of 67.7 (6.9) years, mean (SD) BMD T-scores of -1.6 (0.9), -1.9 (0.7), and -2.2 (1.2) at the total hip, femoral neck, and lumbar spine, respectively, and median sCTX-1 of 0.3 ng/mL at baseline. At month 12, denosumab significantly increased BMD compared with risedronate at the total hip (2.0% vs 0.5%), femoral neck (1.4% vs 0%), and lumbar spine (3.4% vs 1.1%; p<0.0001 at all sites). Denosumab significantly decreased sCTX-1 compared with risedronate at month 1 (median change from baseline of -78% vs -17%; p<0.0001) and month 6 (-61% vs -23%; p<0.0001). Overall and serious adverse events were similar between groups. In postmenopausal women who were suboptimally adherent to alendronate therapy, transitioning to denosumab was well tolerated and more effective than risedronate in increasing BMD and reducing bone turnover.

Complement c3 is inversely associated with habitual intake of provitamin A but not with dietary fat, fatty acids, or vitamin E in middle-aged to older white adults and positively associated with intake of retinol in middle-aged to older white women

Complement factor 3 (C3) has been identified as a novel risk factor for obesity-associated cardiometabolic diseases. Data in the literature suggest that C3 concentrations may be influenced by diet. Therefore, we investigated the associations of intake of total fat, specific fatty acids, and fat-soluble vitamin E (and individual tocopherols) and vitamin A (and its dietary precursors) with circulating C3. In a white cohort [Cohort on Diabetes and Atherosclerosis Maastricht (CODAM); n = 501; 59.4 ± 7.1 y; 61% men], associations of habitual nutrient intake (assessed by a food-frequency questionnaire) with circulating C3 were evaluated by using cross-sectional multiple linear regression analyses. Adjustments were first performed for age, sex, glucose metabolism status (i.e., impaired glucose metabolism or type 2 diabetes), and energy intake and subsequently for BMI, waist circumference, alcohol intake, smoking behavior, and season of blood collection. No associations with C3 were observed for total dietary fat intake or intake of specific fatty acids [saturated, monounsaturated, polyunsaturated, n-6 (ω-6), and n-3 (ω- 3) fatty acids], vitamin E, or individual tocopherols. We observed an inverse association with intake of provitamin A carotenoids α-carotene (in μg/d; regression coefficient β = -0.075; 95% CI: -0.140, -0.010; P = 0.025) and β-carotene (in μg/d; β = -0.021; 95% CI: -0.044, 0.002; P = 0.068) with C3 (in mg/L). In contrast, and only in women, dietary retinol intake (in μg/d) was positively associated with C3 (β = 0.116; 95% CI: 0.014, 0.218; P = 0.026; n = 196). In conclusion, these data suggest that fasting concentrations of C3 may, in a complex manner, be modifiable by variation in dietary provitamin A carotenoids and/or retinol content of the usual diet but most likely not by variations in fat composition and vitamin E content.

Adapted dietary inflammatory index and its association with a summary score for low-grade inflammation and markers of glucose metabolism: the Cohort study on Diabetes and Atherosclerosis Maastricht (CODAM) and the Hoorn study

BACKGROUND

Diet may be associated with the development of type 2 diabetes through its effects on low-grade inflammation.

OBJECTIVES

We investigated whether an adapted dietary inflammatory index (ADII) is associated with a summary score for low-grade inflammation and markers of glucose metabolism. In addition, we investigated the mediating role of inflammation in the association between ADII and markers of glucose metabolism.

DESIGN

We performed cross-sectional analyses of 2 Dutch cohort studies (n= 1024). An ADII was obtained by multiplying standardized energy-adjusted intakes of dietary components by literature-based dietary inflammatory weights that reflected the inflammatory potential of components. Subsequently, these multiplications were summed. Six biomarkers of inflammation were compiled in a summary score. Associations of the ADII (expressed per SD) with the summary score for inflammation and markers of glucose metabolism were investigated by using multiple linear regression models. Inflammation was considered a potential mediator in the analysis with markers of glucose metabolism.

RESULTS

A higher ADII was associated with a higher summary score for inflammation [β-adjusted = 0.04 per SD (95% CI: 0.01, 0.07 per SD)]. The ADII was also adversely associated with insulin resistance [homeostatic model assessment of insulin resistance (HOMA-IR): β-adjusted = 3.5% per SD (95% CI: 0.6%, 6.3% per SD)]. This association was attenuated after the inclusion of the summary score for inflammation [β-adjusted+inflammation = 2.2% (95% CI: -0.6%, 5.0%)]. The ADII was also adversely associated with fasting glucose and postload glucose but not with glycated hemoglobin.

CONCLUSION

The significant mediating role of low-grade inflammation in the association between the ADII and HOMA-IR suggests that inflammation might be one of the pathways through which diet affects insulin resistance.