Victoria E. Rogers

γ-Tocopherol-rich supplementation additively improves vascular endothelial function during smoking cessation☆

Oxidative stress and inflammation persist years after smoking cessation thereby limiting the restoration of vascular endothelial function (VEF). Although short-term smoking cessation improves VEF, no studies have examined co-therapy of antioxidants in combination with smoking cessation to improve VEF. We hypothesized that improvements in γ-tocopherol (γ-T) status during smoking cessation would improve VEF beyond that from smoking cessation alone by decreasing oxidative stress and proinflammatory responses. A randomized, double-blind, placebo-controlled study was conducted in otherwise healthy smokers (22 ± 1 years; mean ± SEM) who quit smoking for 7 days with placebo (n=14) or γ-T-rich supplementation (n=16; 500 mg γ-T/day). Brachial artery flow-mediated dilation (FMD), cotinine, and biomarkers of antioxidant status, oxidative stress, and inflammation were measured before and after 7 days of smoking cessation. Smoking cessation regardless of supplementation similarly decreased plasma cotinine, whereas γ-T-rich supplementation increased plasma γ-T by seven times and its urinary metabolite γ-carboxyethyl hydroxychroman by nine times (P<0.05). Smoking cessation with γ-T-rich supplementation increased FMD responses by 1.3% (P<0.05) beyond smoking cessation alone (4.1 ± 0.6% vs 2.8 ± 0.3%; mean ± SEM). Although plasma malondialdehyde decreased similarly in both groups (P<0.05), plasma oxidized LDL and urinary F2-isoprostanes were unaffected by smoking cessation or γ-T-rich supplementation. Plasma TNF-α and myeloperoxidase decreased (P<0.05) only in those receiving γ-T-rich supplements and these were inversely related to FMD (P<0.05; R=-0.46 and -0.37, respectively). These findings demonstrate that short-term γ-T-rich supplementation in combination with smoking cessation improved VEF beyond that from smoking cessation alone in young smokers, probably by decreasing the proinflammatory mediators TNF-α and myeloperoxidase.

Vitamin D deficiency associates with γ-tocopherol and quadriceps weakness but not inflammatory cytokines in subjects with knee osteoarthritis.

Knee osteoarthritis (OA) is a degenerative joint condition and a leading cause of physical disability in the United States. Quadriceps weakness and inflammatory cytokines contribute to the pathogenesis of knee OA, and both of which, increase with vitamin D deficiency. Other micronutrients, such as vitamins C and E and β-carotene, modulate inflammatory cytokines and decrease during inflammation. The purpose of this study was to test the hypothesis that vitamin D deficiency associates with quadriceps weakness, an increase in serum cytokines, and a decrease in circulating micronutrients in subjects with knee OA. Subjects (age, 48±1 y; serum 25(OH)D, 25.8±1.1 ng/mL) with knee OA were categorized as vitamin D deficient (n=17; serum 25(OH)D≤20 ng/mL), insufficient (n=21; serum 25(OH)D 20–29 ng/mL), or sufficient (n=18; serum 25(OH)D≥30 ng/mL). Single-leg strength (concentric knee extension–flexion contraction cycles at 60 °/s) and blood cytokine, carotene (α and β), ascorbic acid, and tocopherol (α and γ) concentrations were measured. Quadriceps peak torque, average power, total work, and deceleration were significantly (all p<0.05) impaired with vitamin D deficiency. Serum γ-tocopherol concentrations were significantly (p<0.05) increased with vitamin D deficiency. In the vitamin D sufficient group, γ-tocopherol inversely correlated (r=−0.47, p<0.05) with TNF-α, suggesting a pro-inflammatory increase with a γ-tocopherol decrease despite a sufficient serum 25(OH)D concentration. We conclude that vitamin D deficiency is detrimental to quadriceps function, and in subjects with vitamin D sufficiency, γ-tocopherol could have an important anti-inflammatory role in a pathophysiological condition mediated by inflammation.

Pro-inflammatory cytokines mediate the decrease in serum 25(OH)D concentrations after total knee arthroplasty?

Vitamin D is a fat-soluble micronutrient that regulates inflammation and skeletal muscle size and function. Inflammation and skeletal muscle dysfunction (i.e., atrophy and weakness) are predominant impairments that continue to challenge the rehabilitation from total knee arthroplasty (TKA). Data suggest a decrease in serum 25-hydroxyvitamin D (25(OH)D) concentrations after TKA. Despite the decrease being attributed to a systemic inflammatory response, it is unclear what inflammatory mediator(s) is contributing to the decrease in serum 25(OH)D concentrations after TKA. In immune cells, pro-inflammatory cytokines mediate the enzymatic conversion of 25(OH)D to 1,25-dihydroxyvitamin D, implying that pro-inflammatory cytokines contribute to the decrease in substrate availability (i.e., 25(OH)D). We propose the hypothesis that pro-inflammatory cytokines mediate the decrease in serum 25(OH)D concentrations after TKA. To complement the supporting literature for the proposed hypothesis, we analyzed serum 25(OH)D and pro-inflammatory cytokine concentrations prior to and serially after TKA in a case subject (female; age, 62 year; height, 160 cm; body mass, 63 kg; body mass index, 26.5 kg/m(2)). The subtle decrease (12%) from pre-surgery to 2-d post-surgery and the more pronounced decrease (74%) from 3-week to 8-week post-surgery in serum 25(OH)D concentrations corresponded with the increase in serum pro-inflammatory cytokine (i.e., TNF-α, IFN-γ, IL-1β, GM-CSF, and IL-6) concentrations. This observation lends credence to the proposed hypothesis that pro-inflammatory cytokines could contribute to the decrease in serum 25(OH)D concentrations after TKA. Clearly, future research is needed to confirm the proposed hypothesis and to identify if attenuating the decrease in serum 25(OH)D concentrations improves patient outcomes after TKA.

Supplemental vitamin D increases serum cytokines in those with initially low 25-hydroxyvitamin D: a randomized, double blind, placebo-controlled study.

The purpose of this study was to determine if vitamin D status before supplementation influences the cytokine response after supplemental vitamin D. Forty-six reportedly healthy adults (mean(SD); age, 32(7) y; body mass index (BMI), 25.3(4.5) kg/m(2); serum 25-hydroxyvitamin D (25(OH)D), 34.8(12.2) ng/mL) were randomly assigned (double blind) to one of three groups: (1) placebo (n=15), or supplemental vitamin D (cholecalciferol) at (2) 4000 (n=14) or (3) 8000IU (n=17). Supplements were taken daily for 35days. Fasting blood samples were obtained before (Baseline, Bsl) and 35-days after (35-d) supplementation. Serum 25(OH)D, 1,25-dihydroxyvitamin D (1,25(OH)D), cytokines, and intact parathyroid hormone with calcium were measured in each blood sample. Supplemental vitamin D increased serum 25(OH)D (4000IU, ≈29%; 8000IU, ≈57%) and 1,25(OH)D (4000IU, ≈12%; 8000IU, ≈38%) without altering intact parathyroid hormone or calcium. The vitamin D metabolite increases in the supplemental vitamin D groups (n=31) were dependent on initial levels as serum 25(OH)D (r=-0.63, p<0.05) and 1,25(OH)D (r=-0.45, p<0.05) at Bsl correlated with their increases after supplementation. Supplemental vitamin D increased interferon (IFN)-γ and interleukin (IL)-10 in subjects that were vitamin D insufficient (serum 25(OH)D<29ng/mL) compared to sufficient (serum 25(OH)D⩾30ng/mL) at Bsl. We conclude that supplemental vitamin D increase a pro- and anti-inflammatory cytokine in those with initially low serum 25(OH)D.

Serum cytokines are increased and circulating micronutrients are not altered in subjects with early compared to advanced knee osteoarthritis

Knee osteoarthritis (OA) is a leading cause of physical disability. At the early stage of knee OA, the increase in synovial fluid cytokine concentrations could contribute to the pathogenesis of OA by degrading articular cartilage. It is unknown, however, if inflammatory cytokines increase systemically at the early or advanced stage of knee OA. The systemic increase of inflammatory cytokines could be detrimental to the endogenous status of micronutrients that protect against excessive inflammation and cytokine-mediated events. The purpose of this study was to test the hypothesis that an increase in serum cytokines associate with a decrease in circulating micronutrients in subjects with early compared to advanced knee OA. Advanced knee OA subjects (n=14) displayed radiographic, pain, and muscular weakness symptoms of knee OA. Early knee OA subjects (n=14) were matched (age, gender, and body mass index) to the advanced OA group and displayed one or two of the aforementioned symptoms of knee OA. Inflammatory cytokines, vitamins C (ascorbic acid), D (25-hydroxyvitamin D), and E (α- and γ-tocopherols), and β-carotene were measured in fasting blood samples. In the early OA group, serum tumor necrosis factor (TNF)-α, interleukin (IL)-5, IL-6, IL-12, and IL-13 concentrations were significantly (all p<0.05) increased. Circulating ascorbic acid, 25-hydroxyvitamin D, α- and γ-tocopherols, and β-carotene concentrations were not significantly different between groups. Based on these preliminary results, we conclude that the systemic increase of inflammatory cytokines is not associated with a decrease in circulating micronutrients in subjects with early compared to advanced knee OA.

Improvement in muscle strength after an anterior cruciate ligament injury corresponds with a decrease in serum cytokines

The purpose of this communication was to identify if a decrease in serum cytokine concentrations associates with an improvement in muscle strength after an anterior cruciate ligament (ACL) injury. To establish groups with contrasting serum cytokine concentrations, subjects scheduled for ACL reconstructive surgery were separated into one of two groups (gender matched) based on their time from injury occurrence: (1) Early (<21-d from injury occurrence; n=22) or (2) Late (⩾21-d from injury occurrence; n=22). Before surgery, each subject provided a fasting blood sample and performed single-leg peak isometric force testing on the injured (INJ) and non-injured (NI) limbs. Compared to the NI limb, peak isometric force in the INJ limb was decreased (p<0.05) in both groups (Early, ∼35%; Late, ∼18%). The deficit in peak isometric force, however, was increased (p<0.05) in the Early compared to Late group. Similarly, serum granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-6, and IL-13 were increased (all p<0.05) in the Early group. These unique findings show a concurrent increase in muscular weakness and serum cytokine concentrations shortly after (<21-d) an ACL injury. Importantly, muscular weakness persisted thereafter (⩾21-d) but at an attenuated level and parallel to a decrease in circulating cytokine concentrations. We conclude that a decrease in serum cytokines associates with a reduction in muscular weakness after an ACL injury.

Soluble TNF Receptors are Modulated by Vitamin D Status but not by Acute Perturbations in 25-Hydroxyvitamin D Following A Bolus of Supplemental Vitamin D

The first objective of this study was to identify if soluble tumor necrosis factor-receptor 1 (sTNFr1) and -receptor 2 (sTNFr2) are modulated by vitamin D status (insufficient vs. sufficient). The second objective was to reveal if soluble TNF receptors fluctuate with serum 25-hydroxyvitamin D (25(OH)D) concentrations following a bolus of supplemental vitamin D. Reportedly healthy male adults were randomly (double-blind) assigned to a placebo (n=15) or vitamin D (100,000 IU of cholecalciferol; n=14) supplement. Supplements were taken as a bolus immediately after and on the same day as providing the first blood sample (baseline (Bsl)). Fasting blood samples were also obtained at 1-, 3-, 7-, and 24-d after the bolus. Serum 25(OH)D, 1,25-dihyroxyvitamin D (1,25(OH)D), tumor necrosis factor (TNF)-α, sTNFr1, and sTNFr2 were measured in each blood sample. At Bsl, subjects were classified as vitamin D insufficient (serum 25(OH)D

Circulating interleukin-6 is not altered while γ-tocopherol is increased in subjects scheduled for knee surgery with low vitamin D

The purpose of this study was to identify if circulating interleukin (IL)-6 and γ-tocopherol (γT) fluctuate with vitamin D status in subjects with an underlying knee joint injury or disease. We hypothesized that low vitamin D associates with an increase in plasma γT while serum IL-6 remains unchanged in subjects with an underlying knee joint trauma or disease. Fifty-four subjects scheduled to undergo primary, unilateral anterior cruciate ligament reconstructive surgery (ACL; n=27) or total knee arthroplasty (TKA; n=27) were studied. Circulating γT, α-tocopherol (αT), lipids (cholesterol and triglycerides), IL-6, and 25-hydroxyvitamin D (25(OH)D) were measured in fasting blood samples obtained prior to surgery. Subjects were classified as vitamin D deficient, insufficient, or sufficient if they had a serum 25(OH)D concentration <50, 50-75, or >75nM, respectively. The majority (57%) of the subjects possessed a serum 25(OH)D less than 50nM. Circulating cholesterol, triglycerides, and IL-6 were not significantly (all p>0.05) different between vitamin D status groups. However, lipid corrected αT was significantly (p<0.05) decreased and both lipid- and non-lipid-corrected plasma γT concentrations were significantly (both p<0.05) increased with low serum 25(OH)D (i.e., <50nM). A significant (p<0.05) multi-variate analysis revealed that an increase in plasma γT per lipids was significantly (p<0.05) predicted by a decrease in serum 25(OH)D but not by a decrease in plasma αT per lipids. We conclude that low vitamin D associates with an increase in plasma γT but not IL-6 in subjects with an underlying joint injury or disease.

Serum cytokines and muscle strength after anterior cruciate ligament surgery are not modulated by high-doses of vitamins E (α- and γ-tocopherol's) and C.

The purpose of this investigation was to identify if supplemental vitamin E (consisting of α- and γ-tocopherols) and C modulate serum cytokine and muscle strength following an ACL injury and surgery. Subjects were randomly assigned to one of two groups: (1) placebo (n=14) or (2) vitamins E (α-[600m g RRR-α-tocopherol, αT] and γ-[600 mg of RRR-γT]) and C (1000 mg ascorbic acid, AA) (EC; n=15). Supplements were taken daily starting ∼2-wk prior to and concluding 16-wk after surgery. Fasting blood samples were obtained and single-leg peak isometric force measurements were performed at baseline (prior to supplementation), before surgery (∼120-min - blood draw only), and 8-wk, 12-wk, and 16-wk after surgery. αT, γT, AA, and cytokines were measured in each blood sample, and peak isometric force was measured on the injured and non-injured legs separately at each testing session. An exercise protocol consisting of repetitive knee and hip extension and flexion contractions to exhaustion was performed on the injured limb at 16-wk. Vitamin E and C supplementation significantly (all p<0.05) increased plasma αT (∼40%), γT (∼160%), and AA (∼50%) concentrations. Serum cytokine concentrations, peak isometric force, and time to exhaustion during the exercise protocol were not significantly different between groups. Based on these findings, we conclude that vitamin E and C supplementation increases their endogenous levels without minimizing muscular weakness or modulating serum cytokine concentrations after ACL surgery.