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School of Nursing, Institute of Clinical Sciences, University of Birmingham, Edgbaston, Birmingham, UK
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Vitamin D has well-documented effects on calcium homeostasis and bone metabolism but recent studies suggest a much broader role for this secosteroid in human health. Key components of the vitamin D system, notably the vitamin D receptor (VDR) and the vitamin D-activating enzyme (1α-hydroxylase), are present in a wide array of tissues, notably macrophages, dendritic cells and T lymphocytes (T cells) from the immune system. Thus, serum 25-hydroxyvitamin D (25D) can be converted to hormonal 1,25-dihydroxyvitamin D (1,25D) within immune cells, and then interact with VDR and promote transcriptional and epigenomic responses in the same or neighbouring cells. These intracrine and paracrine effects of 1,25D have been shown to drive antibacterial or antiviral innate responses, as well as to attenuate inflammatory T cell adaptive immunity. Beyond these mechanistic observations, association studies have reported the correlation between low serum 25D levels and the risk and severity of human immune disorders including autoimmune diseases such as inflammatory bowel disease, multiple sclerosis, type 1 diabetes and rheumatoid arthritis. The proposed explanation for this is that decreased availability of 25D compromises immune cell synthesis of 1,25D leading to impaired innate immunity and over-exuberant inflammatory adaptive immunity. The aim of the current review is to explore the mechanistic basis for immunomodulatory effects of 25D and 1,25D in greater detail with specific emphasis on how vitamin D-deficiency (low serum levels of 25D) may lead to dysregulation of macrophage, dendritic cell and T cell function and increase the risk of inflammatory autoimmune disease.
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Low plasma levels of vitamin D causes bone mineral change that can precipitate osteopenia and osteoporosis and could aggravate autoimmune diseases, hypertension and diabetes. The demand for vitamin D supplementation becomes necessary; however, the consumption of vitamin D is not without risks, which its toxicity could have potentially serious consequences related to hypervitaminosis D, such as hypercalcemia and cerebral alterations. Thus, the present study describes the electroencephalographic changes caused by supraphysiological doses of vitamin D in the brain electrical dynamics and the electrocardiographic changes. After 4 days of treatment with vitamin D at a dose of 25,000 IU/kg, the serum calcium levels found were increased in comparison with the control group. The electrocorticogram analysis found a reduction in wave activity in the delta, theta, alpha and beta frequency bands. For ECG was observed changes with shortened QT follow-up, which could be related to serum calcium concentration. This study presented important evidence about the cerebral and cardiac alterations caused by high doses of vitamin D, indicating valuable parameters in the screening and decision-making process for diagnosing patients with symptoms suggestive of intoxication.
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Purpose
This study aims to investigate the associations of the systemic immune-inflammation index (SII) with bone mineral density (BMD) and osteoporosis in adult females from a nationally representative sample.
Methods
A cross-sectional study was performed among 4092 females aged ≥20 years from the National Health and Nutrition Examination Survey 2007–2010. Linear and logistic regressions were applied to explore the relationships of SII with BMD and the risk of osteoporosis, respectively.
Results
Linear regression analyses found that a doubling of SII levels was significantly correlated with a 1.39% (95% CI: 0.57%, 2.20%) decrease in total femur BMD, a 1.16% (95% CI: 0.31%, 2.00%) decrease in femur neck BMD, a 1.73% (95% CI: 0.78%, 2.66%) decrease in trochanter BMD, and a 1.35% (95% CI: 0.50%, 2.20%) decrease in intertrochanteric BMD among postmenopausal women, after adjusting for covariates. Logistic regression analyses showed that compared with postmenopausal women in the lowest SII quartile, those in the highest quartile had higher risks of osteoporosis in the total femur (odds ratio (OR) = 1.70, 95% CI: 1.04, 2.76), trochanter (OR = 1.86, 95% CI: 1.07, 3.38), intertrochanter (OR = 2.01, 95% CI: 1.05, 4.04) as well as overall osteoporosis (OR = 1.57, 95% CI: 1.04, 2.37). In contrast, there was no significant association between SII and BMD in premenopausal women.
Conclusions
SII levels were negatively associated with BMD levels in postmenopausal women but not in premenopausal women. Elevated SII levels could be a potential risk factor for osteoporosis in postmenopausal women.
