High levels of serum vitamin D-binding protein in patients with psoriasis: A case-control study and effects of ultraviolet B phototherapy

The association between vitamin D binding protein levels and periodontal status: A systematic review

BACKGROUND AND OBJECTIVES

Vitamin D binding protein (DBP) is biosynthesised in the liver and is predominantly expressed in serum. Its primary role centres on facilitating the systemic transportation of vitamin D and its metabolites, notably 25-hydroxyvitamin D, to specific target tissues where vitamin D exerts its biological functions. Due to the paucity of studies, it is unclear whether there is an association between DBP and periodontal status and thus its potential use as a diagnostic biomarker. Therefore, the aim of the systematic review is to investigate the association between DBP in periodontal disease.

METHODS

Two independent reviewers (YD and RG) performed a systematic literature search of English publications using several databases including MEDLINE (OVID interface, 1946 onwards), EMBASE (OVID interface, 1974 onwards), and Global Health (OVID interface, 1973 onwards). This search strategy enabled the identification of relevant publications and the development of a comprehensive library of studies. Studies were included based on previously agreed eligibility criteria. Of the eight studies included as part of this systematic review, seven were case-control studies and one was a cross-sectional study. The quality assessment was based on the Newcastle-Ottawa Scale (NOS) for case-control studies and the modified NOS for the cross-sectional study.

RESULTS

The NOS quality assessment was 'favorable' for 6 included case control studies; and 'fair' for one study. The modified NOS quality assessment for the single cross-sectional study demonstrated a medium risk of bias. The results of the majority of the included studies indicated a statistically significant higher concentration of DBP levels in individuals with periodontitis in comparison to those who were periodontally healthy. This trend held true irrespective of the sampling method employed for the assessment of DBP concentration.

CONCLUSION

The results summarised in this systematic review indicate a positive association between DBP and periodontitis. Nonetheless, there is a need for longitudinal, prospective trials, to confirm the use of DBP as a potential biomarker for the diagnosis of periodontitis.

Phototherapy-induced hypocalcemia and hypoparathyroidism in icteric term newborns

OBJECTIVES

Phototherapy is demonstrated to cause hypocalcemia by decreasing melatonin levels and increasing cortisol levels. However, the relationship between parathyroid hormone (PTH) level and calcium has not been previously evaluated in patients receiving phototherapy. Our study aimed to evaluate the effect of phototherapy on ionized calcium (iCa), total calcium (tCa), corrected calcium (cCa), magnesium (Mg), phosphorus (P), 25-hydroxyvitamin D (25(OH)D), and PTH levels.

METHODS

Infants who were born at term and received inpatient phototherapy for indirect hyperbilirubinemia were included in our study. The patients' gestational age, birth weight, and phototherapy durations were recorded. Total bilirubin, albumin, iCa, tCa, cCa, Mg, 25(OH)D, and PTH levels before and after phototherapy were compared. Laboratory results were also compared between patients who received phototherapy for ≤24 h, 25-47 h, and ≥48 h.

RESULTS

A total of 166 term infants were included in the study. The mean duration of phototherapy was 31.9 ± 9.2 h. Albumin levels before and after phototherapy were similar (p=0.246). However, there were significant decreases in iCa, tCa, cCa, Mg, 25(OH)D, and PTH levels after phototherapy (p<0.001), while P level was significantly increased after phototherapy (p<0.001). In addition, P levels increased with >24 h of phototherapy, while iCa, tCa, cCa, Mg, 25(OH)D, and PTH levels decreased significantly with ≥48 h of phototherapy (p=0.002, p=0.008, p=0.001, p=0.012, and p<0.001, respectively).

CONCLUSIONS

This study demonstrates that PTH suppression is one of the causes of phototherapy-induced hypocalcemia.

Vitamin D Signaling in Psoriasis: Pathogenesis and Therapy

Psoriasis is a systemic, chronic, immune-mediated disease that affects approximately 2–3% of the world’s population. The etiology and pathophysiology of psoriasis are still unknown, but the activation of the adaptive immune system with the main role of T-cells is key in psoriasis pathogenesis. The modulation of the local neuroendocrine system with the downregulation of pro-inflammatory and the upregulation of anti-inflammatory messengers represent a promising adjuvant treatment in psoriasis therapies. Vitamin D receptors and vitamin D-mediated signaling pathways function in the skin and are essential in maintaining the skin homeostasis. The active forms of vitamin D act as powerful immunomodulators of clinical response in psoriatic patients and represent the effective and safe adjuvant treatments for psoriasis, even when high doses of vitamin D are administered. The phototherapy of psoriasis, especially UVB-based, changes the serum level of 25(OH)D, but the correlation of 25(OH)D changes and psoriasis improvement need more clinical trials, since contradictory data have been published. Vitamin D derivatives can improve the efficacy of psoriasis phototherapy without inducing adverse side effects. The anti-psoriatic treatment could include non-calcemic CYP11A1-derived vitamin D hydroxyderivatives that would act on the VDR or as inverse agonists on RORs or activate alternative nuclear receptors including AhR and LXRs. In conclusion, vitamin D signaling can play an important role in the natural history of psoriasis. Selective targeting of proper nuclear receptors could represent potential treatment options in psoriasis.

Vitamin D-Binding Protein and the Free Hormone Hypothesis for Vitamin D in Bio-Naïve Patients with Psoriasis

High levels of vitamin D-binding protein (DBP) have been reported in patients with psoriasis and the possibility of DBP as a marker of inflammation has been discussed. Furthermore, high DBP levels might negatively affect free 25(OH)D concentrations. According to the free hormone hypothesis, only the free fraction of a steroid hormone is capable of exerting biological action. Thus, free 25(OH)D level could be a better biomarker of vitamin D status than total 25(OH)D level. The objectives of this study were to identify the strongest determinants for DBP levels and to test the free hormone hypothesis for vitamin D in psoriasis. Additionally, we also aimed to investigate correlations between directly measured free 25(OH)D levels in serum and psoriasis disease severity compared to total 25(OH)D levels. This was a retrospective cross-sectional study including 40 bio-naïve patients with mild to severe plaque psoriasis. Psoriasis disease severity was evaluated using high sensitivity C-reactive protein (hsCRP), Psoriasis Area Severity Index (PASI) and visual analogue scale (VAS). Vitamin D metabolites including directly measured free 25(OH)D and serum DBP levels were measured. DBP levels were higher in patients with self-reported arthropathy than those without irrespective of confounding factors like sex, age and body weight. Total and free 25(OH)D levels correlated well (ρ = 0.77, p < 0.0001) and both were inversely correlated to intact parathyroid hormone (iPTH) (ρ = −0.33, p = 0.038 for total 25(OH)D and ρ = −0.40, p = 0.010 for free 25(OH)D). Only total 25(OH)D correlated to serum calcium levels (ρ = 0.32, p = 0.047). No correlations between any of the vitamin D metabolites and psoriasis disease severity were observed. In conclusion, DBP might be a new inflammatory biomarker in psoriasis, especially in psoriatic arthritis. Total 25(OH)D was a reliable measure for vitamin D status in this psoriasis cohort. However, evaluation of free 25(OH)D in patients with psoriatic disease and multiple co-morbidities and/or ongoing biologic treatment should be considered.

Impact of Etanercept on Vitamin D Status and Vitamin D-binding Protein in Bio-naïve Patients with Psoriasis

High levels of serum vitamin D-binding protein have been shown previously in patients with psoriasis compared with healthy controls; a possible role in inflammation is implied. The primary objective of this study was to investigate the impact of 24-week etanercept treatment on vitamin D status and vitamin D-binding protein in patients with psoriasis. The secondary aim was to explore whether pre-treatment vitamin D levels could predict the treatment effect. A prospective observational study was performed, including 20 patients with psoriasis and 15 controls. Serum samples were analyzed for, among others, vitamin D metabolites, vitamin D-binding protein and highly sensitive Creactive protein. Baseline levels of vitamin D-binding protein were higher in patients with self-reported arthropathy than in those without. After 24 weeks’ treatment, an improvement in psoriasis was noted, as was a decrease in highly sensitive C-reactive protein. Vitamin D-binding protein decreased in those with self-reported arthropathy. Higher baseline levels of vitamin D were associated with faster and greater improvement in psoriasis. Vitamin D-binding protein may have an inflammatory biomarker role.