Osteoporose na artrite reumatoide: papel do sistema vitamina D/hormônio paratireóideo

The Potential Role of Vitamin D Supplementation in Cognitive Impairment Prevention

BACKGROUND

Vitamin D is implicated in many processes in the central nervous system (CNS), such as neurogenesis, neurotransmitter synthesis, synaptogenesis and protection against oxidative stress, thereby exerting a neuroprotective effect.

OBJECTIVE

In the present review, we aimed to evaluate the potential benefit(s) of vitamin D supplementation for CNS aging in different clinical contexts.

METHODS

We performed a literature search, looking for clinical trials and randomized clinical trials evaluating the effect of vitamin D supplementation on different endpoints related to cognitive outcomes.

RESULTS

Firstly, we identified 16 papers dealing with the impact of vitamin D supplementation on cognitive function in healthy subjects; the current literature suggests a real role for vitamin D supplementation in the prevention of cognitive decay in this clinical setting. Conversely, two papers suggest that vitamin D supplementation may be beneficial in patients with mild cognitive impairment (MCI). Finally, current data on vitamin D in Alzheimer's disease are contradictory.

CONCLUSION

Vitamin D supplementation may improve the cognitive outcomes of patients with MCI, whereas there is no evidence that it may prevent dementia or modulate the course of Alzheimer's disease.

Increased Prevalence of Autoimmune Rheumatologic Diseases in Patients With Primary Hyperparathyroidism

Background Parathyroid hormone (PTH) and Dickkopf-related protein 1 (DKK-1) have been mentioned together at the intersection of autoimmune rheumatologic diseases (ARDs) and osteoimmunology. However, few studies have evaluated the association between primary hyperparathyroidism (PHPT) and ARDs. Methodology This retrospective study included 225 PHPT patients and 386 patients with thyroid nodules as a control group. The electronic hospital records of all patients were screened going back nine years for the presence of ARDs. Patients who were diagnosed at least three months ago, had complete serologic tests, and were continuing with rheumatologic follow-up were included. Results The prevalence of ARDs in the PHPT group was 9.77% (22/225), while the prevalence of ARDs in the CG was 1.04% (4/386, p < 0.001). The prevalence of rheumatoid arthritis in the PHPT group was 4.4% (10/225), ankylosing spondylitis 3.1% (7/225), systemic lupus erythematosus 0.88% (2/225), Behçet's disease 0.88% (2/225), and mixed connective tissue disease 0.44% (1/225). Of the 22 patients with ARDs, 21 (95.45%) were diagnosed before they were diagnosed with PHPT, and the median time from diagnosis with ARD to the onset of PHPT was 36 months (interquartile range = 61.5). Logistic regression analysis showed a positive correlation between the duration of PHPT and ARDs (odds ratio (OR) = 1.06; 95% confidence interval (CI) = 1.02-1.09, p < 0.001) and a negative correlation between ARDs and calcium levels (OR = 0.26; 95% CI = 0.09-0.79, p = 0.018). Conclusions The prevalence of ARDs increased in PHPT patients and PHPT accompanying ARDs developed after rheumatologic disease. ARDs with PHPT are cases with a prolonged duration of PHPT and mildly elevated calcium, probably preceded by parathyroid hyperplasia. Therefore, the factors that cause ARDs may trigger a process that leads to mild PHPT.

Vitamin D in Systemic Sclerosis: A Review

(1) Background: In the present paper we aimed to review the evidence about the potential implication of vitamin D in the pathogenesis and management of systemic sclerosis (SSc); (2) Methods: we performed a review of the literature looking for studies evaluating the potential role of vitamin D and its analogs in SSc. We searched the PubMed, Medline, Embase, and Cochrane libraries using the following strings: (vitamin D OR cholecalciferol) AND (systemic sclerosis OR scleroderma). We included cohort studies, case-control studies, randomized controlled trials, and observational studies. (3) Results: we identified nine pre-clinical and 21 clinical studies. Pre-clinical data suggest that vitamin D and its analogs may suppress fibrogenesis. Clinical data are concordant in reporting a high prevalence of hypovitaminosis D and osteoporosis in SSc patients; data about the association with clinical manifestations and phenotypes of SSc are, conversely, far less consistent; (4) Conclusions: in vitro data suggest that vitamin D may play an antifibrotic role in SSc, but clinical data confirming this finding are currently lacking. Hypovitaminosis D is common among SSc patients and should be treated to reduce the risk of osteoporosis.

Pathophysiological Role and Therapeutic Implications of Vitamin D in Autoimmunity: Focus on Chronic Autoimmune Diseases

Vitamin D is a pleiotropic secosteroid yielding multiple actions in human physiology. Besides the canonical regulatory activity on bone metabolism, several non-classical actions have been described and the ability of vitamin D to partake in the regulation of the immune system is particularly interesting, though far stronger and convincing evidence has been collected in in vitro as compared to in vivo studies. Whether vitamin D is able to regulate at physiological concentrations the human immune system remains unproven to date. Consequently, it is not established if vitamin D status is a factor involved in the pathogenesis of immune-mediated diseases and if cholecalciferol supplementation acts as an adjuvant for autoimmune diseases. The development of autoimmunity is a heterogeneous process, which may involve different organs and systems with a wide range of clinical implications. In the present paper, we reviewed the current evidences regarding vitamin D role in the pathogenesis and management of different autoimmune diseases.

To Supplement or not to Supplement? The Rationale of Vitamin D Supplementation in Systemic Lupus Erythematosus

Background:

Systemic Lupus Erythematosus (SLE) is a systemic autoimmune disease characterised by abnormal activation of the immune system, chronic inflammation and organ damage. Lupus patients are more prone to be vitamin D deficient. However, current evidence is not conclusive with regards to the role played by vitamin D in SLE development, progression, and clinical manifestations.

Objective:

Here, we will summarise the current knowledge about vitamin D deficiency prevalence, risk factors, molecular effects, and potential pathogenic role in SLE. We will focus on the link between vitamin D deficiency and lupus clinical manifestations, and on the clinical trials assessing the effects of vitamin D supplementation in SLE.

Method:

A detailed literature search was performed exploiting the available databases, using “vitamin D and lupus/SLE” as keywords. The relevant interventional trials published over the last decade have been considered and the results are reported here.

Conclusion:

Several immune cells express vitamin D receptors. Thus, an immunomodulatory role for vitamin D in lupus is plausible. Numerous observational studies have investigated the relationship between vitamin D levels and clinical/serological manifestations of SLE with contrasting results. Negative correlations between vitamin D levels and disease activity, fatigue, renal and cardiovascular disease, and anti-dsDNA titres have been described but not conclusively accepted. In experimental models of lupus, vitamin D supplementation can improve the disease. Interventional trials have assessed the potential therapeutic value of vitamin D in SLE, but further larger studies are needed.

Vitamin D and Type I Diabetes

Vitamin D is a fat-soluble vitamin that plays an important role in bone metabolism but is also endowed with the capability of modulating inflammatory and immune function. Recent studies reported a relationship between low vitamin D levels and several autoimmune diseases such as Type 1 Diabetes. Vitamin D regulates the expression of over 200 genes, also related to immune modulation, suggesting a putative role in these diseases pathogenesis. This review overviews the most recent advances on the association between vitamin D and increased risk of Type 1 Diabetes as well as between vitamin D and either glucose homeostasis or insulin sensitivity. The effects of vitamin D in modulating the immune response and balancing anti-inflammatory cytokines, suggest that vitamin D system may represent an unforeseen target for the design of novel strategies for the treatment of patients with autoimmune diseases and in particular Type 1 Diabetes.

New Insights on Low Vitamin D Plasma Concentration as a Potential Cardiovascular Risk Factor

The role of Vitamin D hormone in human health and disease is still debated. Recently, growing attention has been paid to its putative role in cardiovascular system homeostasis with several studies that suggested a correlation between low vitamin D levels and increased cardiovascular risk. Several mechanisms are involved in the development of cardiovascular diseases: systemic inflammation, endothelial dysfunction, arterial hypertension and insulin resistance. In the present paper, we have revised the current literature supporting a role for vitamin D in the development of these pathogenetic processes. Finally, we have evaluated the current evidence linking vitamin D to atherosclerosis and its natural consequence, cardiovascular diseases.

Detrimental Impact of Interferon-Based Regimens for Chronic Hepatitis C on Vitamin D/Parathyroid Hormone Homeostasis

Background:

Both the anti-infective and anti-inflammatory properties of vitamin D, an essential hormone of calcium homeostasis, have ample support in the literature. The high rates of vitamin D deficiency among patients with chronic hepatitis C are also well known. That supplementation with vitamin D may boost sustained viral response rates in vitamin D deficient, hepatitis C virus (HCV) infected patients undergoing Interferon-alpha (IFN) treatment, on the other hand, is controversial. Surprisingly, studies considering in this latter setting what are the effects of IFN treatment (with or without vitamin D supplementation) on the other major regulator of mineral metabolism, i.e. the Parathyroid hormone (PTH), are lacking.

Aim:

Evaluate the impact of interferon-based treatment against HCV (±cholecalciferol supplementation) on vitamin D and PTH homeostasis.

Methods:

A series of 40 consecutive patients received pegylated IFN plus ribavirin to treat chronic hepatitis C. At the discretion of their physician, some of them (N. = 27) received vitamin D supplementation while others did not (N. = 13). All had measured plasma 25-hydroxycholecalciferol and PTH concentrations at baseline, at completion of the 4th (TW4) and 12th treatment week (TW12) and at 24 weeks after the end of therapy (SVR24).

Results:

Plasma PTH concentration increased significantly from baseline during treatment, raising to 44.8 [30.7-57.2] pg/mL at TW4 (p=0.01), 47.0 [37.1-63.2] pg/mL at TW12 (p=0.006) to return to baseline levels in the follow-up (34.5 [27.6-43.0]; p=0.16). The proportion of patients who satisfied criteria for hyperparathyroidism was higher at TW12 (N=10, 25%) than at TW4 (N=6, 15%). There was no statistical correlation between vitamin D and PTH blood levels (ρ=-0.07; p=0.65).

Conclusion:

An increase in plasma PTH occurs systematically during IFN treatment of HCV patients and cannot be prevented by vitamin D supplementation.

Vitamin D, Inflammation and Osteoporosis in Rheumatoid Arthritis

Patients with Rheumatoid Arthritis (RA) commonly develop osteoporosis and fragility fractures. This fact cannot be explained only with the use of glucocorticoids, known to be detrimental for bone health. RA is characterized by a chronic inflammation caused by the continuous activation of innate and adaptive immunity with proinflammatory cytokines overproduction. This process is detrimental for several organs and physiological processes, including the impairment of bone remodeling. We will briefly review the pathogenesis of inflammation-related bone loss in RA, describing well-known and new molecular pathways and focusing on vitamin D and Parathyroid Hormone role.

Role of Vitamin D in Rheumatoid Arthritis

Vitamin D is a fat soluble hormone, with a well described role in bone health and calcium/phosphate metabolism. Recent evidences have related vitamin D to other physiological functions and pathological conditions. Specifically, vitamin D has widely proven activities on immune system and evidences suggest that it may be implicated in the pathogenesis of rheumatoid arthritis (RA). The relationship between vitamin D and RA is complex, also because a deficitary vitamin D status, which is very common in RA patients, can contribute to the increased risk of osteoporosis typical of RA. In this chapter, will be described and discussed the main aspects of the relationship between RA and vitamin D.