Vitamin D, innate immunity, and sarcoidosis granulomatous inflammation: insights from mycobacterial research

Vitamin D Supplementation in Sarcoidosis: A Double-Edged Sword

Sarcoidosis is complicated by disordered vitamin D and calcium metabolism, which has important implications on disease activity and bone health. Although the majority of the patients with sarcoidosis are typically deficient in 25-hydroxyvitamin D, repletion of vitamin D is controversial in light of the hypercalcemia risk. Presently, there are no clear guidelines regarding vitamin D supplementation as a part of osteoporosis prevention in patients with vitamin D deficiency and sarcoidosis. We report a patient with sarcoidosis who presented with severe hypercalcemia following vitamin D supplementation and review the debated role of vitamin D supplementation in vitamin D-deficient sarcoid patients.

The role of vitamin D in sarcoidosis

After the initial description of extrarenal synthesis of 1,25-dihydroxyvitamin D (1,25-(OH)₂D) three decades ago, extensive progress has been made in unraveling the immunomodulatory roles of vitamin D in the pathogenesis of granulomatous disorders, including sarcoidosis. It has been shown that 1,25-(OH)₂D has dual effects on the immune system, including upregulating innate immunity as well as downregulating the autoimmune response. The latter mechanism plays an important role in the pathogenesis and treatment of sarcoidosis. Vitamin D supplementation in patients with sarcoidosis has been hampered owing to concerns about the development of hypercalcemia and hypercalciuria given that extrarenal 1-α hydroxylase is substrate dependent. Recently, a few studies have cast doubt over the mechanisms underlying the development of hypercalcemia in this population. These studies demonstrated an inverse relationship between the level of vitamin D and severity of sarcoidosis. Consequently, clinical interest has been piqued in the use of vitamin D to attenuate the autoimmune response in this disorder. However, the development of hypercalcemia and the attendant detrimental effects are real possibilities. Although the average serum calcium concentration did not change following vitamin D supplementation, in two recent studies, hypercalciuria occurred in one out of 13 and two out of 16 patients. This review is a concise summary of the literature, outlining past work and newer developments in the use of vitamin D in sarcoidosis. We feel that larger-scale placebo-controlled randomized studies are needed in this population. Since the current first-line treatment of sarcoidosis is glucocorticoids, which confer many systemic adverse effects, and steroid-sparing immunosuppressant treatment options carry additional risks of adverse effects, adjunct management with vitamin D in combination with potent anti-osteoporotic medications could minimize the risk of glucocorticoid-induced osteoporosis and modulate the immune system to attenuate disease activity in sarcoidosis.

Lung gene expression signatures suggest pathogenic links and molecular markers for pulmonary tuberculosis, adenocarcinoma and sarcoidosis

Previous reports have suggested a link between pulmonary tuberculosis (TB), which is caused by Mycobacterium tuberculosis (Mtb), and the development of lung adenocarcinoma (LUAD) and sarcoidosis. Furthermore, these lung diseases share certain clinical similarities that can challenge differential diagnosis in some cases. Here, through comparison of lung transcriptome-derived molecular signatures of TB, LUAD and sarcoidosis patients, we identify certain shared disease-related expression patterns. We also demonstrate that MKI67, an over-expressed gene shared by TB and LUAD, is a key mediator in Mtb-promoted tumor cell proliferation, migration, and invasion. Moreover, we reveal a distinct ossification-related TB lung signature, which may be associated with the activation of the BMP/SMAD/RUNX2 pathway in Mtb-infected macrophages that can restrain mycobacterial survival and promote osteogenic differentiation of mesenchymal stem cells. Taken together, these findings provide novel pathogenic links and potential molecular markers for better understanding and differential diagnosis of pulmonary TB, LUAD and sarcoidosis.

Previous work has suggested potential links between Mycobacterium tuberculosis infection and the development of both lung cancer and sarcoidosis, in addition to tuberculosis. Here, Qiyao Chai, Zhe Lu, Zhidong Liu and colleagues report a transcriptomic analysis of lung tissue from tuberculosis, lung adenocarcinoma, and sarcoidosis patients and find that while many disease-linked expression changes are shared between the three diseases, each also has distinct transcriptional signatures that could be useful as molecular markers.

Genes and metabolic pathway of sarcoidosis: identification of key players and risk modifiers

INTRODUCTION

Sarcoidosis is a rare multisystem granulomatous disease with unknown etiology. The interplay of vitamin D deficiency and genetic polymorphisms in genes coding for the proteins relevant for metabolism of vitamin D is an important, but unexplored area. The aim of this study was to investigate the association between single nucleotide polymorphisms (SNPs) in CYP2R1 (rs10741657), CYP27B1 (rs10877012), DBP (rs7041; rs4588), and VDR (rs2228570) genes and sarcoidosis, as well as the association between these SNPs and 25(OH)D levels in sarcoidosis patients.

MATERIAL AND METHODS

For that purpose we genotyped 86 sarcoidosis patients and 50 healthy controls using the PCR-RFLP method.

RESULTS

Subjects carrying the CC genotype of CYP27B1 rs10877012 have 10 times lower odds of suffering from sarcoidosis. Moreover, DBP rs4588 AA genotype was shown to be a susceptibility factor, where carriers of this genotype had eight times higher odds for developing sarcoidosis. In addition, the A allele of the DBP gene (rs4588) was associated with lower levels of 25(OH)D in sarcoidosis patients.

CONCLUSIONS

These results suggest that patients with vitamin D deficiency should be regularly tested for genetic modifiers that are related to sarcoidosis in order to prevent development of serious forms of sarcoidosis.

25-Hydroxyvitamin D concentrations in dogs with naturally acquired blastomycosis

Background

Hypovitaminosis D is common in humans with tuberculosis, and adequate serum 25‐hydroxyvitamin D [25(OH)D] concentrations may improve response to therapy. The pathomechanism of Blastomyces dermatitidis is similar to that of Mycobacterium tuberculosis, but the 25(OH)D status of dogs with blastomycosis has not been investigated.

Objectives

To determine if dogs with blastomycosis have lower 25(OH)D concentrations compared with healthy controls and to explore the prognostic value of 25(OH)D concentrations in blastomycosis.

Animals

35 control dogs (16 client‐owned, healthy dogs and 19 healthy, random‐source hound mixes) and 22 dogs with blastomycosis.

Methods

Prospective study. Serum concentrations of 25(OH)D, parathyroid hormone (PTH), ionized calcium were measured, and biochemistry and hematology profiles were performed. The 25‐hydroxyvitamin D concentrations were compared between groups, and factors associated with 25(OH)D variation were investigated in dogs with blastomycosis. Dogs with blastomycosis were followed for up to 5 years after discharge and factors associated with survival were investigated.

Results

Dogs with blastomycosis had significantly lower concentrations of 25(OH)D and PTH and higher concentrations of ionized calcium than did control dogs. In dogs with blastomycosis, 25(OH)D concentrations were independently associated with neutrophil count, pCO₂, and with bone and skin involvement. The 25‐hydroxyvitamin D concentration was not associated with survival in dogs with blastomycosis, whereas lactate concentrations; bone, skin, and lymph node involvement; number of affected sites; and, presence of respiratory signs were associated with survival.

Conclusions and Clinical Importance

Dogs with blastomycosis had lower 25(OH)D concentrations than did healthy controls. Despite no impact on survival, investigating the effect of 25(OH)D supplementation on recovery is warranted.

Current concepts regarding calcium metabolism and bone health in sarcoidosis

PURPOSE OF REVIEW

Vitamin D supplementation is widespread used in the general population. In sarcoidosis, up to 50% of patients, especially postmenopausal women and those taking corticosteroids, show evidence of increased bone fragility. The purpose of this review is to provide an evidence-based rationale on how to treat sarcoidosis patients with bone health issues.

RECENT FINDINGS

Evidence from observational studies show that decreased 25-hydroxy vitamin D is common in sarcoidosis. However, the great majority of sarcoidosis patents have normal or often elevated levels of 1,25-dihydroxy vitamin D (calcitriol), a marker associated with disease activity. High calcitriol levels may often be associated with hypercalcemia and hypercalcuria. The few interventional randomized controlled studies in the field, suggest that vitamin D supplementation may not be well tolerated because of hypercalcemia, moreover without substantial benefit on bone health and risk for fractures in these patients.

SUMMARY

Vitamin D supplementation may be withheld in sarcoidosis patients with bone fragility, unless calcitriol levels are below normal limits. A treating scheme is proposed.

Enhanced LPS-induced activation of IL-27 signalling in sarcoidosis

RATIONALE

Granulomas in sarcoidosis have recently been described as containing Interleukin (IL)-27, one of the members of the IL-12 family of cytokines, which also includes IL-35. Levels of these cytokines and the IL-27 receptor subunits were hypothesised to differ between patients with sarcoidosis compared to healthy controls in peripheral blood.

METHODS

Using a cross-sectional study design, plasma and peripheral blood mononuclear cells (PBMC) were collected from patients and control subjects. Protein and mRNA (in PBMC) levels for IL-27 and IL-35 (IL27, EBI3, IL12A subunits) as well as IL-27 receptor (IL6ST and IL27RA subunits) were assessed spontaneously and following direct (LPS) and indirect (anti-CD3/28 activation beads) macrophage stimulation using RT- PCR, ELISA and flow cytometry.

RESULTS

Following stimulation with LPS, PBMC of patients with sarcoidosis displayed significantly enhanced expression of IL27 and EBI3 mRNA (p = 0.020 and p = 0.037 respectively) compared to PBMCs from healthy controls. There was also significantly enhanced production of IL-27 by PBMC from patients with sarcoidosis compared to healthy controls in response to LPS stimulation (p = 0.027). IL6ST mRNA and IL6ST protein were significantly lower in patients with sarcoidosis (mRNA p = 0.0002; MFI p = 0.0015) whilst IL27RA protein levels were significantly higher in patients with sarcoidosis compared to healthy controls (MFI p < 0.0001). Plasma IL-35 protein levels did not differ between control and sarcoidosis subjects (p = 0.23).

CONCLUSION

These results suggest there may be exaggerated activation of IL-27 signalling in response to LPS in sarcoidosis.

Calcium and vitamin D in sarcoidosis: is supplementation safe?

Granulomas in sarcoidosis express high levels of 1α-hydroxylase, an enzyme that catalyzes the hydroxylation of 25-OH vitamin D to its active form, 1,25(OH)2 vitamin D. Overproduction of 1α-hydroxylase is held responsible for the development of hypercalcemia in sarcoidosis patients. Corticosteroids are used as first-line treatment in organ-threatening sarcoidosis. In this light, osteoporosis prevention with calcium and vitamin D (CAD) supplementation is often warranted. However, sarcoidosis patients are at risk for hypercalcemia, and CAD supplementation affects the calcium metabolism. We studied calcium and vitamin D disorders in a large cohort of sarcoidosis patients and investigated if CAD supplementation is safe. Retrospectively, data of 301 sarcoidosis patients from July 1986 to June 2009 were analyzed for serum calcium, 25-hydroxy vitamin D (25-(OH)D), 1,25-dihydroxy vitamin D (1,25(OH)2 D), and use of CAD supplementation. Disease activity of sarcoidosis was compared with serum levels of vitamin D. Hypercalcemia occurred in 8%. A significant negative correlation was found between 25-(OH)D and disease activity of sarcoidosis measured by somatostatin receptor scintigraphy. In our study, 5 of the 104 CAD-supplemented patients developed hypercalcemia, but CAD supplementation was not the cause of hypercalcemia. Patients without CAD supplementation were at higher risk for developing hypercalcemia. During CAD supplementation, no hypercalcemia developed as a result of supplementation. Hypovitaminosis D seems to be related with more disease activity of sarcoidosis and, therefore, could be a potential risk factor for disease activity of sarcoidosis. Thus, vitamin D-deficient sarcoidosis patients should be supplemented.

A practical approach to cutaneous sarcoidosis

Sarcoidosis is a chronic inflammatory disorder that has the potential to affect multiple organs, including the skin. Its cutaneous manifestations are varied and can provide clues to underlying systemic manifestations. Unfortunately, they also can be disfiguring. Therapy is usually directed at the organ system most severely affected, which often may help cutaneous disease. However, cutaneous disease may be recalcitrant to treatment directed at extracutaneous disease, or it may be severe enough to require targeted therapy. This article focuses on the dermatologist's role in recognizing and diagnosing cutaneous sarcoidosis, evaluating patients for systemic disease involvement, and treating the skin manifestations of sarcoidosis.

Muscular sarcoidosis detected by F-18 FDG PET/CT in a hypercalcemic patient

Sarcoidosis is a systemic granulomatous disease of unknown etiology that involves many organs, occasionally mimicking malignancy. We herein report a 50-yr-old woman of muscular sarcoidosis of chronic myopathic type, manifested by hypercalcemia and muscle wasting. Besides insignificant hilar lymphadenopathy, her sarcoidosis was confined to generalized atrophic muscles and therefore, F-18 FDG PET/CT alone among conventional imaging studies provided diagnostic clues for the non-parathyroid-related hypercalcemia. On follow-up PET/CT during low-dose steroid treatment, FDG uptake in the muscles disappeared whereas that in the hilar lymph nodes remained. PET/CT may be useful in the evaluation of unexpected disease extent and monitoring treatment response in suspected or known sarcoidosis patients.

Antimicrobial peptide elicitors: New hope for the post-antibiotic era

Antimicrobial peptides or host defense peptides are fundamental components of human innate immunity. Recent and growing evidence suggests they have a role in a broad range of diseases, including cancer, allergies and susceptibility to infection, including HIV/AIDS. Antimicrobial peptide elicitors (APEs) are physical, biological or chemical agents that boost human antimicrobial peptide expression. The current knowledge of APEs and their potential use in the treatment of human infectious diseases are reviewed, and a classification system for APEs is proposed. The efficient use of APEs in clinical practice could mark the beginning of the urgently needed post-antibiotic era, but further trials assessing their efficacy and safety are required.

Bone health issues in sarcoidosis

Sarcoidosis affects the bone directly in only a minority of patients. Nonetheless, bone health should be considered in the management of all patients with sarcoidosis. Deficiency in vitamin D, an important contributor to bone health, has been linked to autoimmune disease incidence. Studies have shown that patients with sarcoidosis frequently have low levels of vitamin D-25 but may have normal or increased levels of vitamin D-1,25. In addition, granuloma formation has been linked to a failure of the innate immune system, which could be related to a deficiency in vitamin D, although this relationship has not been fully characterized. Furthermore, many patients with sarcoidosis are treated with corticosteroids, which are known to induce osteoporosis. Therefore, bone health may be impacted in several ways in sarcoidosis--by direct involvement with granulomas, vitamin D deficiency, or corticosteroid therapy.