Impact of vitamin D on infectious disease

The Vitamin D for Enhancing the Immune System in Cystic Fibrosis (DISC) trial: Rationale and design of a multi-center, double-blind, placebo-controlled trial of high dose bolus administration of vitamin D3 during acute pulmonary exacerbation of cystic fibrosis

Vitamin D deficiency is highly prevalent in children and adults with cystic fibrosis (CF). Recent studies have found an association between vitamin D status and risk of pulmonary exacerbations in children and adults with CF. The ongoing Vitamin D for enhancing the Immune System in Cystic fibrosis (DISC) study is a multi-center, double-blind, randomized, placebo-controlled trial that will test the hypothesis of whether high dose vitamin D given as a single oral bolus of 250,000 IU to adults with CF during a pulmonary exacerbation followed by a maintenance dose of vitamin D will improve time to next pulmonary exacerbation and re-hospitalization, improve survival and lung function compared to placebo and reduce the rates of pulmonary exacerbation,. Subjects will be randomized 1:1 at each clinical site to vitamin D or placebo within 72 hours of hospital admission for pulmonary exacerbation. Clinical follow-up visits will occur at 1, 2, 3, and 7 days, and 1, 3, 6 and 12 months after randomization. Blood and sputum will be collected and determination of clinical outcomes will be assessed at each visit. The primary endpoint will be the time to next pulmonary exacerbation requiring antibiotics, re-hospitalization or death. The secondary endpoints will include lung function assessed by forced expiratory volume in 1 second (FEV1), blood markers of inflammatory cytokines, anti-microbial peptide expression by peripheral blood mononuclear cells and circulating concentrations in blood. Other exploratory endpoints will examine the phenotype of neutrophils and monocyte/macrophages in sputum. Nutritional status will be assessed by 3 day food records and food frequency questionnaire.

Evaluation of vitamin status in patients with pulmonary tuberculosis

OBJECTIVE

Vitamins are known to be associated with immunity and nutrition. Moreover, vitamin deficiency can affect host immunity to various infectious diseases, including tuberculosis. Although patients with tuberculosis often have vitamin D deficiency, little is known about the levels of other vitamins. Here, we aimed to investigate the status of vitamins A, B12, D, and E in patients with tuberculosis. We also aimed to investigate the clinical and laboratory variables related to vitamin status in patients with tuberculosis.

METHODS

We performed a case-control study to investigate the serum vitamin concentrations in 152 patients with tuberculosis and 137 control subjects. The concentrations of vitamin A, vitamin D, vitamin E, homocysteine, and methylmalonic acid were measured using high-performance liquid chromatography (HPLC) or HPLC-tandem mass spectrometry. Patient demographic data and other biochemical parameters were also analyzed.

RESULTS

The serum concentrations of vitamins A, D, and E were significantly lower in patients with tuberculosis than in control subjects (1.4 vs. 2.0 μmol/L, P < 0.001; 10.6 vs. 19.3 ng/mL, P < 0.001; and 22.8 vs. 30.6 μmol/L, P < 0.001, respectively). In contrast, the methylmalonic acid levels were higher in patients with tuberculosis (134.9 vs. 110.8 nmol/L, P < 0.001). The prevalences of vitamin deficiencies were significantly higher in patients with tuberculosis. Moreover, multiple vitamin deficiencies were only observed in patients with tuberculosis (22.4% of all patients with tuberculosis vs. 0% of all control subjects). Positive correlations among vitamin A, D, and E concentrations were observed (vitamins A and D, r = 0.395; vitamins D and E, r = 0.342; and vitamins A and E, r = 0.427, P < 0.001). Body mass index, total cholesterol, low-density lipoprotein, iron, and total iron-binding capacity all showed positive correlations with vitamin A, D, and E concentrations.

CONCLUSIONS

Vitamin deficiencies are common in patients with tuberculosis. Further research investigating the clinical importance of vitamin and nutritional status in patients with tuberculosis is needed.

Vitamin D: not just the bone. Evidence for beneficial pleiotropic extraskeletal effects

Vitamin D is a fat-soluble vitamin and a steroid hormone that plays a central role in maintaining calcium-phosphorus and bone homeostasis in close interaction with parathyroid hormone, acting on its classical target tissues, namely, bone, kidney, intestine, and parathyroid glands. However, vitamin D endocrine system regulates several genes (about 3 % of the human genome) involved in cell differentiation, cell-cycle control, and cell function and exerts noncalcemic/pleiotropic effects on extraskeletal target tissues, such as immune and cardiovascular system, pancreatic endocrine cells, muscle, and adipose tissue. Several studies have demonstrated the role of vitamin D supplementation in the prevention/treatment of various autoimmune diseases and improvement of glucose metabolism, muscle, and adipose tissue function. Hence, this review aims to elucidate the effects of vitamin D on extraskeletal target tissues and to investigate the potential therapeutic benefit of vitamin D supplementation among a broad group of pathological conditions, especially with regard to metabolic and autoimmune diseases. In addition, we focused on the best daily intakes and serum levels of vitamin D required for extraskeletal benefits which, even if still controversial, appear to be higher than those widely accepted for skeletal effects.

Efficacy of vitamin D3 supplementation in reducing incidence of pulmonary tuberculosis and mortality among HIV-infected Tanzanian adults initiating antiretroviral therapy: study protocol for a randomized controlled trial

Background

HIV-infected adults initiating antiretroviral therapy (ART) in sub-Saharan Africa continue to experience high rates of morbidity and mortality during the initial months of treatment. Observational studies in high-income and resource-limited settings indicate that HIV-infected adults with low vitamin D levels may be at increased risk of mortality, HIV disease progression, and incidence of pulmonary tuberculosis (TB). As a result, vitamin D₃ supplementation may improve survival and treatment outcomes for HIV-infected adults initiating ART.

Methods/Design

The Trial of Vitamins-4 (ToV4) is an individually randomized, double-blind, placebo-controlled trial of vitamin D₃ (cholecalciferol) supplementation conducted among 4000 HIV-infected adults with low vitamin D levels [25-hydroxyvitamin D (25(OH)D) <30 ng/mL] initiating ART in Dar es Salaam, Tanzania. The two primary aims of the trial are to determine the effect of a vitamin D₃ supplementation regimen on incidence of (1) mortality and (2) pulmonary TB as compared to a matching placebo regimen. The primary safety outcome of the study is incident hypercalcemia. The investigational vitamin D₃ regimen consists of oral supplements containing 50,000 IU vitamin D₃ taken under direct observation at randomization and once a week for 3 weeks (four doses) followed by daily oral supplements containing 2000 IU vitamin D₃ taken at home from the fourth week until trial discharge at 1 year post ART initiation. Trial participants are followed up at weekly clinic visits during the first month of ART and at monthly clinic visits thereafter until trial discharge at 1 year post ART initiation. Secondary aims of the trial are to examine the effect of the vitamin D₃ regimen on CD4 T cell reconstitution, incidence of non-TB comorbidities, body mass index (BMI), depression and anxiety, physical activity, bone health, and immunologic biomarkers.

Discussion

The ToV4 will provide causal evidence on the effect of vitamin D₃ supplementation on incidence of pulmonary TB and mortality among HIV-infected Tanzanian adults initiating ART. The trial will also give insight to whether vitamin D₃ supplementation trials for the prevention of pulmonary TB should be pursued in HIV-uninfected populations.

Trial registration

ClinicalTrials.gov, NCT01798680. Registered on 21 February 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1819-5) contains supplementary material, which is available to authorized users.

The association of the vitamin D status with the persistence of anti-HBs antibody at 20years after primary vaccination with recombinant hepatitis B vaccine in infancy

BACKGROUND AND OBJECTIVE

Vitamin D has potent immunoregulatory effects due to the expression of its receptor on the majority of immune cells. The aim was to evaluate the association of the vitamin D status with the persistence of anti-HBs antibody and immune response to booster immunization at 20years after primary vaccination with hepatitis B (HB) vaccine.

METHODS

Blood samples were collected from 300 adults 20years after completion of the primary HB vaccination in infancy. The serum levels of vitamin D and anti-HBs antibody were measured by ELISA. A single booster dose of a recombinant HB vaccine was administered to a total of 138 subjects, whose anti-HBs titer was<10IU/L. The sera of revaccinated subjects were re-tested for anti-HBs antibody, 4weeks after booster vaccination.

RESULTS

At 20years after primary vaccination, the mean vitamin D concentrations were significantly higher in seroprotective subjects as compared to non-seroprotective individuals (P<0.01). The levels of anti-HBs were significantly increased with advanced concentrations of vitamin D (P<0.01). Overall, 125/138 (90.6%) of the revaccinated subjects showed an anamnestic response to booster vaccination. The concentrations of vitamin D were significantly higher in subjects with an anamnestic response to booster vaccination as compared with subjects without this response (P<0.01).

CONCLUSION

Vitamin D status may influence the persistence of anti-HBs antibody and durability of protection after primary vaccination with a recombinant HB vaccine in infancy.

Vitamin D deficiency: What does it mean for chronic obstructive pulmonary disease (COPD)? a compherensive review for pulmonologists

OBJECTIVES

Vitamin D deficiency and Chronic Obstructive Pulmonary Disease (COPD) are both under-recognized health problems, world-wide. Although Vitamin D has long been known for calcemic effects it also has less known noncalcemic effects. Recent data have shown that Vitamin D deficiency is highly prevalent in patients with COPD and correlates with forced expiratory volume in one second (FEV₁ ) and FEV₁ decline. The objective of this work was to review the current literature on vitamin D deficiency in relation with COPD.

DATA SOURCE

A literature search, using the words "vitamin D" and "COPD", was undertaken in Pubmed database.

RESULTS

The noncalcemic effects of vitamin D relating with COPD may be summarised as increasing antimicrobial peptide production, regulation of inflammatory response and airway remodelling. Vitamin D inhibits the production of several proinflammatory cytokines and leads to suppression Th1 and Th17 responses which may be involved in the pathogenesis of COPD. Vitamin D insufficiency may also contribute to chronic respiratory infections and airway colonization so returning vitamin D concentrations to an optimal range in patients with COPD might reduce bacterial load and concomitant exacerbations.Vitamin D is also important for COPD-related comorbodities such as osteoporosis, muscle weakness and cardiovascular diseases. Data about the effect of Vitamin D supplementation on those comorbidities in relation with COPD are been scarce.

CONCLUSION

Improving the blood level of Vitamin D into the desired range may have a beneficial effect bones and muscles, but more studies are needed to test to test that hypothesis.

Human cytomegalovirus infection downregulates vitamin-D receptor in mammalian cells

Vitamin D (VD) is essential for the human body and involved in a wide variety of critical physiological processes including bone, muscle, and cardiovascular health, as well as innate immunity and antimicrobial responses. Here, we elucidated the significance of the VD system in cytomegalovirus (CMV) infection, which is one of the most common opportunistic infections in immunocompromised or -suppressed patients. We found that expression of vitamin D receptor (VDR) was downregulated in CMV-infected cells within 12h [hrs] post infection [p.i.] to 12% relative to VDR expression in mock-infected fibroblasts and did not recover during the CMV replication cycle of 96h. None of the biologically active metabolites of VD, cholecalciferol, calcidiol, or calcitriol, inhibit CMV replication significantly in human fibroblasts. In a feedback loop, expression of CYP24A1 dropped to 3% by 12h p.i. and expression of CYP27B1 increased gradually during the replication cycle of CMV to 970% probably as a consequence of VDR inhibition. VDR expression was not downregulated during influenza virus or adenovirus replication. The potent synthetic vitamin D analog EB-1089 was not able to inhibit CMV replication or antagonize its effect on VDR expression. Only CMV replication, and none of the other viral pathogens evaluated, inhibited the vitamin D system in vitro. In view of the pleiotropism of VDR, CMV-mediated downregulation may have far-reaching virological, immunological, and clinical implications and thus warrant further evaluations in vitro and in vivo.

The Effects of First-Line Anti-Tuberculosis Drugs on the Actions of Vitamin D in Human Macrophages

Tuberculosis (TB) is a major global health problem. Patients with TB have a high rate of vitamin D deficiency, both at diagnosis and during the course of treatment with anti-tuberculosis drugs. Although data on the efficacy of vitamin D supplementation on Mycobacterium tuberculosis (Mtb) clearance is uncertain from randomized controlled trials (RCTs), vitamin D enhances the expression of the anti-microbial peptide human cathelicidin (hCAP18) in cultured macrophages in vitro. One possible explanation for the mixed (primarily negative) results of RCTs examining vitamin D treatment in TB infection is that anti-TB drugs given to enrolled subjects may impact actions of vitamin D to enhance cathelicidin in macrophages. To address this hypothesis, human macrophage-like monocytic (THP-1) cells were treated with varying doses of first-line anti-tuberculosis drugs in the presence of the active form of vitamin D, 1N1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃). The expression of hCAP18 was determined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). 1,25(OH)₂D₃ strongly induced expression of hCAP18 mRNA in THP-1 cells (fold-change from control). The combination of the standard 4-drug TB therapy (isoniazid, rifampicin, pyrazinamide and ethambutol) in the cultured THP-1 cells demonstrated a significant decrease of hCAP18 mRNA at the dosage of 10 ug/mL. In 31 subjects with newly diagnosed drug-sensitive TB randomized to either high-dose vitamin D₃ (1.2 million IU over 8 weeks, n=13) versus placebo (n=18), there was no change from baseline to week 8 in hCAP18 mRNA levels in peripheral blood mononuclear cells or in plasma concentrations of LL-37, the protein product of hCAP18.These data suggest that first-line anti-TB drugs may alter the vitamin D-dependent increase in hCAP18 and LL-37 human macrophages.

Interactions of Aspergillus fumigatus Conidia with Airway Epithelial Cells: A Critical Review

Aspergillus fumigatus is an environmental filamentous fungus that also acts as an opportunistic pathogen able to cause a variety of symptoms, from an allergic response to a life-threatening disseminated fungal infection. The infectious agents are inhaled conidia whose first point of contact is most likely to be an airway epithelial cell (AEC). The interaction between epithelial cells and conidia is multifaceted and complex, and has implications for later steps in pathogenesis. Increasing evidence has demonstrated a key role for the airway epithelium in the response to respiratory pathogens, particularly at early stages of infection; therefore, elucidating the early stages of interaction of conidia with AECs is essential to understand the establishment of infection in cohorts of at-risk patients. Here, we present a comprehensive review of the early interactions between A. fumigatus and AECs, including bronchial and alveolar epithelial cells. We describe mechanisms of adhesion, internalization of conidia by AECs, the immune response of AECs, as well as the role of fungal virulence factors, and patterns of fungal gene expression characteristic of early infection. A clear understanding of the mechanisms involved in the early establishment of infection by A. fumigatus could point to novel targets for therapy and prophylaxis.

Vitamin D and airway infections: a European perspective

Vitamin D has immuno-modulatory properties, and deficient levels of circulating 25-hydroxyvitamin D (<30 nmol/l) may contribute to increased risk of infectious illnesses. This narrative review summarises data on vitamin D status in Europe and updates results of randomised controlled trials (RCTs) regarding vitamin D and airway infections such as tuberculosis (TB) and acute upper respiratory tract infection. In Europe, the prevalence of vitamin D deficiency is up to 37% in the general population and up to 80% in nursing home residents and non-European immigrants. Half of TB patients have a migration background. While results of RCTs do not support the concept of beneficial adjunctive effects of vitamin D supplements in anti-TB treatment [odds ratio (OR) = 0.86; 95% CI 0.62-1.19], the few published RCTs on the prophylaxis of TB suggest some protective vitamin D effects in individuals with deficient circulating 25-hydroxyvitamin D levels. Regarding acute respiratory tract infection, RCTs indicate a significant risk reduction by vitamin D supplements [OR = 0.65; 95% confidence interval (CI) 0.50-0.85]. There is evidence that daily administration is more effective than high-dose bolus administration [OR = 0.48 (95% CI 0.30-0.77) vs. OR = 0.87 (95% CI 0.67-1.14)] and that individuals with deficient or insufficient (30-50 nmol/l) circulating 25-hydroxyvitamin D levels benefit most. Several vitamin D effects on innate immunity may explain these protective effects. In summary, there is possible evidence from RCTs for protective vitamin D effects on TB and likely evidence for protective effects on acute airway infection. Since vitamin D deficiency is prevalent in Europe, especially in institutionalised individuals and non-European immigrants, daily oral vitamin D intake, e.g. 1000 international units, is an inexpensive measure to ensure adequate vitamin D status in individuals at risk.

What diseases are causally linked to vitamin D deficiency?

The classical clinical consequence of vitamin D deficiency is osteomalacia, presenting as rickets in children. This remains a common problem in parts of the Middle East and the Indian subcontinent, and occurs when serum 25-hydroxyvitamin D levels are <25 nmol/L. Osteomalacia remains the only problem that is unequivocally a consequence of vitamin D deficiency. Low levels of 25-hydroxyvitamin D are observed in a wide range of conditions, but consistent trial evidence of amelioration of these conditions with vitamin D is lacking. Monotherapy with vitamin D has not been found to be effective in meta-analyses of trials assessing its effects on bone density, fractures or falls. At present, supplements should be advised for individuals at risk of having serum 25-hydroxyvitamin D levels in the 25-40 nmol/L range, or below, with a view to prevention of osteomalacia.

Mycobacterial infection induces a specific human innate immune response

The innate immune system provides the first response to infection and is now recognized to be partially pathogen-specific. Mycobacterium tuberculosis (MTB) is able to subvert the innate immune response and survive inside macrophages. Curiously, only 5-10% of otherwise healthy individuals infected with MTB develop active tuberculosis (TB). We do not yet understand the genetic basis underlying this individual-specific susceptibility. Moreover, we still do not know which properties of the innate immune response are specific to MTB infection. To identify immune responses that are specific to MTB, we infected macrophages with eight different bacteria, including different MTB strains and related mycobacteria, and studied their transcriptional response. We identified a novel subset of genes whose regulation was affected specifically by infection with mycobacteria. This subset includes genes involved in phagosome maturation, superoxide production, response to vitamin D, macrophage chemotaxis, and sialic acid synthesis. We suggest that genetic variants that affect the function or regulation of these genes should be considered candidate loci for explaining TB susceptibility.

Vitamin D every day to keep the infection away?

Within the last decade, vitamin D has emerged as a central regulator of host defense against infections. In this regard, vitamin D triggers effective antimicrobial pathways against bacterial, fungal and viral pathogens in cells of the human innate immune system. However, vitamin D also mediates potent tolerogenic effects: it is generally believed that vitamin D attenuates inflammation and acquired immunity, and thus potentially limits collateral tissue damage. Nevertheless, several studies indicate that vitamin D promotes aspects of acquired host defense. Clinically, vitamin D deficiency has been associated with an increased risk for various infectious diseases in epidemiological studies; yet, robust data from controlled trials investigating the use of vitamin D as a preventive or therapeutic agent are missing. In this review, we summarize the current knowledge regarding the effect of vitamin D on innate and acquired host defense, and speculate on the difficulties to translate the available molecular medicine data into practical therapeutic or preventive recommendations.

Autophagy in the fight against tuberculosis

Tuberculosis (TB), a chronic infectious disease mainly caused by the tubercle bacillus Mycobacterium tuberculosis, is one of the world's deadliest diseases that has afflicted humanity since ancient times. Although the number of people falling ill with TB each year is declining, its incidence in many developing countries is still a major cause of concern. Upon invading host cells by phagocytosis, M. tuberculosis can replicate within infected cells by arresting the maturation of the phagosome whose function is to target the pathogen for elimination. Host cells have mechanisms of controlling this evasion by inducing autophagy, an elaborate cellular process that targets bacteria for progressive elimination, decreasing bacterial loads within infected cells. In addition, autophagy activation also aids in the control of inflammation, contributing to a more efficient innate immune response against M. tuberculosis. Several innovative TB therapies have been envisaged based on autophagy manipulation, with some of them revealing high potential for future clinical trials and eventual implementation in healthcare systems. Thus, this review highlights the recent advances on the innate immune response regulation by autophagy upon M. tuberculosis infection and the promising new autophagy-based therapies for TB.