BCG vaccination: a role for vitamin D?

The osteo-metabolic phenotype of COVID-19: an update

CONTEXT

In the multifaceted COVID-19 clinical scenario characterized by a multi-system disorder with negative implications not only on respiratory function but also on cardiac, hematological, neurological and endocrine-metabolic systems, a distinctive osteo-metabolic phenotype with an independent influence on disease severity and recovery of patients affected was early reported.

AIM

To summarize and update the main evidences regarding the distinct components of this phenotype in acute and Long COVID-19, reinforcing its clinical relevance and discussing the main pathophysiological and clinical-therapeutic implications of the most recent reported findings.

RESULTS

This emerging phenotype is characterized by a widespread acute hypocalcemia and hypovitaminosis D with an impaired compensatory parathyroid hormone response, and a high prevalence of skeletal complications such as vertebral fractures. The clinical relevance of this osteo-metabolic phenotype on acute COVID-19 is well characterized, and novel seminal evidences are progressively highlighting its importance also in predicting patient's long-term outcomes and Long COVID-19 occurrence.

CONCLUSIONS

These findings reinforced the central role of a multidisciplinary team, including endocrinologists, in evaluating these patients for a proactive search of each aspect of the osteo-metabolic phenotype components since they may represent suitable therapeutic targets to prevent SARS-CoV-2 infection, poor COVID-19 outcomes, Long COVID-19 occurrence and even possibly better responses to COVID-19 vaccination.

Progressive Host-Directed Strategies to Potentiate BCG Vaccination Against Tuberculosis

The pursuit to improve the TB control program comprising one approved vaccine, M. bovis Bacille Calmette-Guerin (BCG) has directed researchers to explore progressive approaches to halt the eternal TB pandemic. Mycobacterium tuberculosis (M.tb) was first identified as the causative agent of TB in 1882 by Dr. Robert Koch. However, TB has plagued living beings since ancient times and continues to endure as an eternal scourge ravaging even with existing chemoprophylaxis and preventive therapy. We have scientifically come a long way since then, but despite accessibility to the standard antimycobacterial antibiotics and prophylactic vaccine, almost one-fourth of humankind is infected latently with M.tb. Existing therapeutics fail to control TB, due to the upsurge of drug-resistant strains and increasing incidents of co-infections in immune-compromised individuals. Unresponsiveness to established antibiotics leaves patients with no therapeutic possibilities. Hence the search for an efficacious TB immunization strategy is a global health priority. Researchers are paving the course for efficient vaccination strategies with the radically advanced operation of core principles of protective immune responses against M.tb. In this review; we have reassessed the progression of the TB vaccination program comprising BCG immunization in children and potential stratagems to reinforce BCG-induced protection in adults.

Effectiveness of Comirnaty® Vaccine and Correlates of Immunogenicity and Adverse Reactions: A Single-Center Prospective Case Series Study

The literature suggests that real-world data on the effectiveness and safety of the BNT162b2 vaccine depend on the characteristics of the vaccinated volunteers. The purpose of this study was to evaluate antibody responses and kinetics, established association with sociodemographic and clinical characteristics, and adverse reactions after complete vaccination with the BNT162b2 vaccine. A single-center prospective case series study was conducted with 112 eligible volunteers who were institutionalized elderly and health care workers with had a negative anti-SARS-CoV-2 IgG test prior to receiving the first dose of vaccine. At least one serological antibody test after each dose of vaccine was performed. Volunteers with a positive SARS-CoV-2 PCR test before vaccination were excluded. A chemiluminescent immunoassay anti-S1 antibody assay performed a serological evaluation. Both vaccine doses elicited positive IgG antibodies 3799.0 ± 2503.0 AU/mL and 8212.0 ± 4731.0 AU/mL after 20 days of the first and second doses of BNT162b2, respectively. Comirnaty® vaccine induced an immune response with antibody production against SARS-CoV-2 in 100% of participants, regardless of age (Spearman rho = −0.10, p-value = 0.312), body mass index (Spearman rho = 0.05, p-value = 0.640), blood group first dose (p-value for Kruskal−Wallis test = 0.093) and second dose (p-value for Kruskal−Wallis test = 0. 268), number of drugs (Spearman rho = −0.07, p-value = 0.490), and number of chronic diseases first dose (p-value for Kruskal−Wallis test = 0.632) and second dose (p-value for Kruskal−Wallis test = 0.510). IgG antibodies to SARS-CoV-2 were intensely elevated after the second administration of the BNT162b2 vaccine. The higher the titer of anti-peptide IgG antibodies generated after the first dose of vaccine, the higher the titer generated by the second dose of vaccine (Spearman rho = 0.86, p-value < 0.001) and the total antibody titer (Spearman rho = 0.93, p-value < 0.001). Furthermore, no serious adverse effects were reported among participants, although mild to moderate adverse effects (local or systemic) were reported after both doses of the BNT162b2 vaccine, being more frequent after the first dose of the vaccine. No participants showed a positive PCR. The BNT162b2 vaccine induces a robust and rapid antibody response regardless of participant characteristics. The second dose might be especially important because of the increased immunogenicity it produces and the possible temporal distancing of the interval between doses. In general, the vaccines were well tolerated.

A prospective trial investigating the role of Serum 25-Hydroxyvitamin D in diagnosis and prognosis of bladder cancer

Purpose

Higher levels of serum 25-hydroxyvitamin D 25(OHD) are associated with better prognosis in breast and colorectal cancer. However, the evidence is still inconclusive for bladder cancer (BC). Herein, we investigated the diagnosis and prognosis roles of serum levels of 25(OHD) in suspected BC patients presented by hematuria.

Methods

This prospective cohort study involved suspected patients of BC presented with hematuria. Patients were evaluated by CT urogram, office cystoscopy and urine cytology with subsequent inpatient biopsy for positive findings. Baseline blood samples were collected for measurement of 25(OHD) by electrochemiluminescence binding assay at the time of diagnosis. Patients with non-muscle-invasive BC (NMIBC) underwent transurethral resection of bladder tumor (TURBT) and adjuvant intravesical chemotherapy or BCG instillation. Patients were followed up for their recurrence status during 10 to 24 months. Recurrence was defined as the first time of NMIBC pathological relapse during the follow up period.

Results

A total of 115 patients were included in the final analysis. Patients had proven pathological BC (64 with NMIBC, and 20 with muscle invasive) and 31 patients were considered as control group. Controls were those patients with BC-free workup (including cytology, cystoscopy, and upper tract imaging). BC group showed a lower level of 25(OHD) than control group 16.47±5.88 versus 28.99±3.19 ng/mL (p<0.001). In addition, muscle invasive group also showed a lower level than NMIBC group 13.17±4.5 versus 17.49±5.04 ng/mL (P = 0.003). During the follow-up period of, tumor recurrence occurred in 16 (25%) of NMIBC patients. The baseline 25(OHD) were decreased in patients who experienced early recurrence; without being statistically significant (15.99 ± 5.17 vs. 18.38 ± 5.14 ng/mL; p = 0.08). 25(OHD) deficiency/insufficiency occurred in 5 (16.1%) and 64 (76.2%) in control and BC patients, respectively, (odds-ratios (OR): 2.13; 95% confidence intervals (CI), 1.52–2.99; P < 0.0001).

Conclusion

Serum 25(OHD) is significantly decreased in BC patients especially those with tumor muscle invasive group. However, the baseline serum 25(OHD) does not predict the recurrence in the NMIBC patients.

The Immunomodulatory Function of Vitamin D, with Particular Reference to SARS-CoV-2

Vaccines are the only way to reduce the morbidity associated to SARS-CoV-2 infection. The appearance of new mutations urges us to increase the effectiveness of vaccines as a complementary alternative. In this context, the use of adjuvant strategies has improved the effectiveness of different vaccines against virus infections such as dengue, influenza, and common cold. Recent reports on patients infected by COVID-19 reveal that low levels of circulating vitamin D correlate with a severe respiratory insufficiency. The immunomodulatory activity of this micronutrient attenuates the synthesis of pro-inflammatory cytokines and at the same time, increases antibody production. Therefore, the present review proposes the use of vitamin D as adjuvant micronutrient to increase the efficacy of vaccines against SARS-CoV-2 infection.

Dietary 25(OH)D3 supplementation to gestating and lactating sows and their progeny affects growth performance, carcass characteristics, blood profiles and myogenic regulatory factor- related gene expression in wean-finish pigs

Objective

This experiment investigated the effects of supplementing vitamin D₃-fortified sow and progeny diets with 25(OH)D₃ on growth performance, carcass characteristics, immunity, and pork meat quality.

Methods

The present study involved the assessment of supplementing the diet of sows and their progeny with or without 25 (OH)D₃ in a 2×2 factorial arrangement on the performance and production characteristics of wean-finish pigs. Forty-eight multiparous sows were assigned to a basal diet containing 2000 IU/kg vitamin D₃ and supplemented without (CON) or with (TRT) 50 μg/kg 25 (OH)D₃. At weaning, a total of 80 pigs each from CON and TRT sows were allocated to weaning and growing-finishing basal diets fortified with 2,500 and 1,750 IU/kg vitamin D₃ respectively and supplemented without or with 50 μg/kg 25(OH)D₃.

Results

Sows fed 25(OH)D₃-supplemented diets improved pre-weaning growth rate of nursing piglets. A significant sow and pig weaning diet effect was observed for growth rate and feed efficiency (p<0.05) during days 1 to 42 post-weaning. Pigs consuming 25(OH)D₃-supplemented diets gained weight faster (p = 0.016), ate more (p = 0.044) and tended to convert feed to gain more efficiently (p = 0.088) than those fed CON diet between days 98 and 140 post-weaning. Supplemental 25(OH)D₃ improved water holding capacity and reduced drip loss of pork meat, increased serum 25(OH)D₃ level, produced higher interleukin-1 and lower interleukin-6 concentrations in blood circulation, downregulated myostatin (MSTN) and upregulated myogenic differentiation (MYOD) and myogenic factor 5 (MYF5) gene expressions (p<0.05).

Conclusion

Supplementing vitamin D₃-fortified sow and wean-finish pig diets with 50 μg/kg 25(OH)D₃ significantly improved production performance suggesting their current dietary vitamin D₃ levels are insufficient. In fulfilling the total need for vitamin D, it is strongly recommended to add 50 μg/kg 25(OH)D₃ “on top” to practical vitamin D₃-fortified sow and wean-finish pig diets deployed under commercial conditions.

A century of BCG: Impact on tuberculosis control and beyond

BCG turns 100 this year and while it might not be the perfect vaccine, it has certainly contributed significantly towards eradication and prevention of spread of tuberculosis (TB). The search for newer and better vaccines for TB is an ongoing endeavor and latest results from trials of candidate TB vaccines such as M72AS01 look promising. However, recent encouraging data from BCG revaccination trials in adults combined with studies on mucosal and intravenous routes of BCG vaccination in non-human primate models have renewed interest in BCG for TB prevention. In addition, several well-demonstrated non-specific effects of BCG, for example, prevention of viral and respiratory infections, give BCG an added advantage. Also, BCG vaccination is currently being widely tested in human clinical trials to determine whether it protects against SARS-CoV-2 infection and/or death with detailed analyses and outcomes from several ongoing trials across the world awaited. Through this review, we attempt to bring together information on various aspects of the BCG-induced immune response, its efficacy in TB control, comparison with other candidate TB vaccines and strategies to improve its efficiency including revaccination and alternate routes of administration. Finally, we discuss the future relevance of BCG use especially in light of its several heterologous benefits.

On BCG Vaccine Protection from COVID-19: A Review

Bacille Calmette-Guérin (BCG) vaccine has been globally used to protect infants against tuberculosis (TB) for about a century. This vaccine has been shown to provide some degree of non-specific protection from other respiratory tract infections. This advantage has encouraged researchers to investigate the potential protection of this vaccine from the coronavirus disease 2019 from different perspectives in the ongoing pandemic. In this study, we have comprehensively reviewed the latest articles on potential vaccine effectiveness of BCG on COVID-19 and summarized the possible impacts of the BCG against SARS-COV-2 in detail.

Serum Vitamin D and Immunogenicity of Influenza Vaccination in the Elderly

Vaccination is the most effective preventive measure that reduces the risk of influenza and post-influenza complications. It prevents influenza-related hospitalizations and deaths in 50-60% and about 80% of patients aged over 65, respectively. There is the clinical plausibility of the association between serum vitamin D (VIT D) content and viral respiratory infections. In this study, we addressed the issue of a vitamin D modulatory effect on the immune response to seasonal influenza vaccination in elderly persons. The study comprised 96 participants aged 60-75 during the 2016/17 epidemic season. After the determination of the baseline content of VIT D and anti-hemagglutinin antibodies (H1, H3, and HB), participants were vaccinated with a trivalent vaccine. The content of the anti-hemagglutinin antibodies was rechecked 4-5 weeks afterward, showing inappreciable alterations. The negative findings of this study make the influence of serum VIT D content on the immunogenicity of influenza vaccination highly unlikely in elderly persons.

Risk factors for diphtheria outbreak in children aged 1-10 years in East Kalimantan Province, Indonesia

Background: Diphtheria remains a health problem, especially in developing countries. In November 2017, the Indonesian Ministry of Health stated that there was a diphtheria outbreak in Indonesia. East Kalimantan is one of the provinces that experienced this disease outbreak. This study analyzes the risk factors for diphtheria outbreak in children aged 1-10 years. Methods: A case-control study was conducted on 37 respondents. Research variables consist of immunization status against diphtheria, pertussis and tetanus (DPT), nutritional status, children mobility, source of transmission, physical home environment (natural lighting, ventilation area, occupancy density, wall and floor type), knowledge of diphtheria and attitudes towards the diphtheria prevention program. Results: We found that the most of the children who had diphtheria had been immunized against DPT. Additionally the nutritional status of children (p=0.049), mobility (p=0.000) and the source of transmission (p=0.020) were significantly associated with diphtheria. Conclusions: Child/parent mobility (OR=8.456) is the main risk factor for diphtheria outbreak. It is recommended to limit the mobility of children to travel to areas that are experiencing increased cases of diphtheria, improve the nutritional status, and further research on the effectiveness of diphtheria vaccine.

Global prevalence and disease burden of vitamin D deficiency: a roadmap for action in low- and middle-income countries

Vitamin D is an essential nutrient for bone health and may influence the risks of respiratory illness, adverse pregnancy outcomes, and chronic diseases of adulthood. Because many countries have a relatively low supply of foods rich in vitamin D and inadequate exposure to natural ultraviolet B (UVB) radiation from sunlight, an important proportion of the global population is at risk of vitamin D deficiency. There is general agreement that the minimum serum/plasma 25-hydroxyvitamin D concentration (25(OH)D) that protects against vitamin D deficiency-related bone disease is approximately 30 nmol/L; therefore, this threshold is suitable to define vitamin D deficiency in population surveys. However, efforts to assess the vitamin D status of populations in low- and middle-income countries have been hampered by limited availability of population-representative 25(OH)D data, particularly among population subgroups most vulnerable to the skeletal and potential extraskeletal consequences of low vitamin D status, namely exclusively breastfed infants, children, adolescents, pregnant and lactating women, and the elderly. In the absence of 25(OH)D data, identification of communities that would benefit from public health interventions to improve vitamin D status may require proxy indicators of the population risk of vitamin D deficiency, such as the prevalence of rickets or metrics of usual UVB exposure. If a high prevalence of vitamin D deficiency is identified (>20% prevalence of 25(OH)D < 30 nmol/L) or the risk for vitamin D deficiency is determined to be high based on proxy indicators (e.g., prevalence of rickets >1%), food fortification and/or targeted vitamin D supplementation policies can be implemented to reduce the burden of vitamin D deficiency-related conditions in vulnerable populations.

The role of UV radiation and vitamin D in the seasonality and outcomes of infectious disease

The seasonality of infectious disease outbreaks suggests that environmental conditions have a significant effect on disease risk. One of the major environmental factors that can affect this is solar radiation, primarily acting through ultraviolet radiation (UVR), and its subsequent control of vitamin D production. Here we show how UVR and vitamin D, which are modified by latitude and season, can affect host and pathogen fitness and relate them to the outcomes of bacterial, viral and vector-borne infections. We conducted a thorough comparison of the molecular and cellular mechanisms of action of UVR and vitamin D on pathogen fitness and host immunity and related these to the effects observed in animal models and clinical trials to understand their independent and complementary effects on infectious disease outcome. UVR and vitamin D share common pathways of innate immune activation primarily via antimicrobial peptide production, and adaptive immune suppression. Whilst UVR can induce vitamin D-independent effects in the skin, such as the generation of photoproducts activating interferon signaling, vitamin D has a larger systemic effect due to its autocrine and paracrine modulation of cellular responses in a range of tissues. However, the seasonal patterns in infectious disease prevalence are not solely driven by variation in UVR and vitamin D levels across latitudes. Vector-borne pathogens show a strong seasonality of infection correlated to climatic conditions favoring their replication. Conversely, pathogens, such as influenza A virus, Mycobacterium tuberculosis and human immunodeficiency virus type 1, have strong evidence to support their interaction with vitamin D. Thus, UVR has both vitamin D-dependent and independent effects on infectious diseases; these effects vary depending on the pathogen of interest and the effects can be complementary or antagonistic.

"Let there be light": the role of vitamin D in the immune response to vaccines

Vitamin D's non-skeletal actions, including immunomodulatory role, have been increasingly recognized. Of significance, many immune cells are able to synthesize a biologically active form of vitamin D from circulating 25-hydroxyvitamin D with subsequent intracrine actions, and the vitamin D receptor is broadly distributed. In this review, we discuss vitamin D's potent role in innate and adaptive immune responses and published studies evaluating the impact of serum vitamin D, vitamin D gene pathway polymorphisms or empiric vitamin D supplementation on vaccine immunogenicity. We highlight existing knowledge gaps and propose the steps needed to advance the science and answer the question of whether vitamin D may prove valuable as a vaccine adjuvant for certain vaccines against infectious diseases.

Diphtheria in Lao PDR: Insufficient Coverage or Ineffective Vaccine?

Background

During late 2012 and early 2013 several outbreaks of diphthe-ria were notified in the North of the Lao People’s Democratic Republic. The aim of this study was to determine whether the re-emergence of this vaccine-preventable disease was due to insufficient vaccination coverage or reduction of vaccine effectiveness within the affected regions.

Methods

A serosurvey was conducted in the Huaphan Province on a cluster sampling of 132 children aged 12–59 months. Serum samples, socio-demographic data, nutri-tional status and vaccination history were collected when available. Anti-diphtheria and anti-tetanus IgG antibody levels were measured by ELISA.

Results

Overall, 63.6% of participants had detectable diphtheria antibodies and 71.2% tetanus antibodies. Factors independently associated with non-vaccination against diphtheria were the distance from the health centre (OR: 6.35 [95% CI: 1.4–28.8], p = 0.01), the Lao Theung ethnicity (OR: 12.2 [95% CI:1,74–85, 4], p = 0.01) and the lack of advice on vac-cination given at birth (OR: 9.8 [95% CI: 1.5–63.8], (p = 0.01) while the level of maternal edu-cation was a protective factor (OR: 0.08 [95% CI: 0.008–0.81], p = 0.03). Most respondents claimed financial difficulties as the main reason for non-vaccination. Out of 55 children whose vaccination certificates stated that they were given all 3 doses of diphtheria-containing vaccine, 83.6% had diphtheria antibodies and 92.7% had tetanus antibodies. Furthermore, despite a high prevalence of stunted and underweight children (53% and 25.8%, respectively), the low levels of anti-diphtheria antibodies were not correlated to the nutritional status.

Conclusions

Our data highlight a significant deficit in both the vaccination coverage and diphtheria vaccine effectiveness within the Huaphan Province. Technical defi-ciencies in the methods of storage and distribution of vaccines as well as unreliability of vac-cination cards are discussed. Several hypotheses are advanced to explain such a decline in immunity against diphtheria and recommendations are provided to prevent future outbreaks.

Can we translate vitamin D immunomodulating effect on innate and adaptive immunity to vaccine response?

Vitamin D (VitD), which is well known for its classic role in the maintenance of bone mineral density, has now become increasingly studied for its extra-skeletal roles. It has an important influence on the body’s immune system and modulates both innate and adaptive immunity and regulates the inflammatory cascade. In this review our aim was to describe how VitD might influence immune responsiveness and its potential modulating role in vaccine immunogenicity. In the first instance, we consider the literature that may provide molecular and genetic support to the idea that VitD status may be related to innate and/or adaptive immune response with a particular focus on vaccine immunogenicity and then discuss observational studies and controlled trials of VitD supplementation conducted in humans. Finally, we conclude with some knowledge gaps surrounding VitD and vaccine response, and that it is still premature to recommend “booster” of VitD at vaccination time to enhance vaccine response.

Myeloid derived suppressor cells are present at high frequency in neonates and suppress in vitro T cell responses

Over 4 million infants die each year from infections, many of which are vaccine-preventable. Young infants respond relatively poorly to many infections and vaccines, but the basis of reduced immunity in infants is ill defined. We sought to investigate whether myeloid-derived suppressor cells (MDSC) represent one potential impediment to protective immunity in early life, which may help inform strategies for effective vaccination prior to pathogen exposure. We enrolled healthy neonates and children in the first 2 years of life along with healthy adult controls to examine the frequency and function of MDSC, a cell population able to potently suppress T cell responses. We found that MDSC, which are rarely seen in healthy adults, are present in high numbers in neonates and their frequency rapidly decreases during the first months of life. We determined that these neonatal MDSC are of granulocytic origin (G-MDSC), and suppress both CD4+ and CD8+ T cell proliferative responses in a contact-dependent manner and gamma interferon production. Understanding the role G-MDSC play in infant immunity could improve vaccine responsiveness in newborns and reduce mortality due to early-life infections.

Serum concentrations of 25-hydroxyvitamin D and immunoglobulins in an older Swiss cohort: results of the Senior Labor Study

BACKGROUND

Vitamin D and the components of humoral immunity play important roles in human health. Older people have lower 25-hydroxyvitamin D (25(OH)D) serum levels than younger adults. We aimed to determine the levels of 25(OH)D serum concentrations in healthy senior citizens and to study their relationship to the levels of components of humoral immunity.

METHODS

A total of 1,470 healthy Swiss men and women, 60 years or older, were recruited for this study. A total of 179 subjects dropped out of the study because of elevated serum concentrations of C-reactive protein. Fasting blood sera were analyzed for 25(OH)D with the high-performance liquid chromatography (HPLC) and for parathyroid hormone (PTH), immunoglobulins and complement C4 and C3 concentrations with immunoassays. The percentage of participants in each of the four 25(OH)D deficiency groups--severely deficient (<10 ng/ml), deficient (10 to 20), insufficient (21 to 29 ng/ml) and normal (>=30 ng/ml)--were statistically compared. The relationship of the major components of the humoral system and age with 25(OH)D levels was also assessed.

RESULTS

About 66% of the subjects had insufficient levels of 25(OH)D. Normal levels of 25(OH)D were found in 26.1% of the subjects of which 21% were males and 30.5% were females (total study population). Severely deficient levels of 25(OH)D were found in 7.98% of the total study population. Low levels of 25(OH)D were positively associated with IgG2 (P = 0.01) and with C4 (P = 0.02), yet were inversely related to levels of IgG1 and IgA (P < 0.05) and C3 (P = 0.01). Serum levels of total IgA, IgG, IgG2 and IgG4 peaked together with 25(OH)D during late summer.

CONCLUSIONS

Approximately two-thirds of the healthy, older Swiss population presented with Vitamin D insufficiency. The incremental shift in IgA and C3 levels might not necessarily reflect a deranged humoral immune defense; however, given the high prevalence of vitamin D deficiency, the importance of this condition in humoral immunity will be worth looking at more closely. This study supports the role of vitamin D in the competent immune system.

How important is vitamin D in preventing infections?

Interaction with the immune system is one of the most recently established nonclassic effects of vitamin D (VitD). For many years, this was considered to be limited to granulomatous diseases in which synthesis of active 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) or calcitriol is known to be increased. However, recent reports have supported a role for 1,25(OH)2D3 in promoting normal function of the innate and adaptive immune systems. Crucially, these effects seem to be mediated not only by the endocrine function of circulating calcitriol but also via paracrine (i.e., refers to effects to adjacent or nearby cells) and/or intracrine activity (i.e., refers to a hormone acting inside a cell) of 1,25(OH)2D3 from its precursor 25(OH)D3, the main circulating metabolite of VitD. The ability of this vitamin to influence human immune responsiveness seems to be highly dependent on the 25(OH)D3 status of individuals and may lead to aberrant response to infection or even to autoimmunity in those who are lacking VitD. The potential health significance of this has been underlined by increasing awareness of impaired status in populations across the globe. This review will examine the current understanding of how VitD status may modulate the responsiveness of the human immune system. Furthermore, we discuss how it may play a role in host resistance to common pathogens and how effective is its supplementation for treatment or prevention of infectious diseases in humans.

How vitamin D works on bone

Vitamin D is important for the normal development and maintenance of bone. The elucidation of the vitamin D activation pathway and the cloning of the vitamin D receptor have advanced our understanding of the actions of vitamin D on bone. The preponderance of evidence indicates that 1,25(OH)₂D₃ enhances bone mineralization through its effects to promote calcium and phosphate absorption. Although 1,25(OH)₂D₃ stimulates bone resorption in vitro, treatment in vivo can prevent bone loss and fracture through several potential mechanisms. The development of vitamin D analogues has provided new therapeutic options for increasing bone mineral density and reducing fractures.

The role of vitamin D in asthma

Vitamin D metabolites are important immune-modulatory hormones and are able to suppress Th2-mediated allergic airway disease. Some genetic factors that may contribute to asthma are regulated by vitamin D, such as vitamin D receptor (VDR), human leukocyte antigen genes (HLA), human Toll-like receptors (TLR), matrix metalloproteinases (MMPs), a disintegrin and metalloprotein-33 (ADAM-33), and poly(ADP-ribosyl) polymerase- 1 (PARP-1). Vitamin D has also been implicated in asthma through its effects on the obesity, bacillus Calmettee Guérin (BCG) vaccination and high vitamin D level, vitamin D supplement, checkpoint protein kinase 1 (Chk1), plasminogen activator inhibitor-1 (PAI-1) and gamma delta T cells (gdT). Vitamin D plays a role in asthma and exerts its action through either genomic and/or non-genomic ways.

Vitamin D in early childhood and the effect on immunity to Mycobacterium tuberculosis

A potential role for vitamin D as a therapeutic immunomodulator in tuberculosis (TB) has been recognised for over 150 years, but has only recently returned to the centre of the research arena due to the increasing awareness of the global vitamin D deficiency epidemic. As early as birth a child is often deficient in vitamin D, which may not only affect their bone metabolism but also modulate their immune function, contributing to the increased susceptibility to many infections seen early in life. Recent studies have begun to explain the mechanisms by which vitamin D affects immunity. Antimicrobial peptides are induced in conjunction with stimulation of innate pattern recognition receptors enhancing immunity to particular infections. In contrast the role of vitamin D within the adaptive immune response appears to be more regulatory in function, perhaps as a mechanism to reduce unwanted inflammation. In this paper we focus on the effect of vitamin D on immunity to TB. Where much of the attention has been paid by past reviews to the role of vitamin D in adult TB patients, this paper, where possible, focuses on research in paediatric populations.

Vitamins A & D inhibit the growth of mycobacteria in radiometric culture

BACKGROUND

The role of vitamins in the combat of disease is usually conceptualized as acting by modulating the immune response of an infected, eukaryotic host. We hypothesized that some vitamins may directly influence the growth of prokaryotes, particularly mycobacteria.

METHODS

The effect of four fat-soluble vitamins was studied in radiometric Bactec® culture. The vitamins were A (including a precursor and three metabolites,) D, E and K. We evaluated eight strains of three mycobacterial species (four of M. avium subspecies paratuberculosis (MAP), two of M. avium and two of M. tb. complex).

PRINCIPAL FINDINGS

Vitamins A and D cause dose-dependent inhibition of all three mycobacterial species studied. Vitamin A is consistently more inhibitory than vitamin D. The vitamin A precursor, β-carotene, is not inhibitory, whereas three vitamin A metabolites cause inhibition. Vitamin K has no effect. Vitamin E causes negligible inhibition in a single strain.

SIGNIFICANCE

We show that vitamin A, its metabolites Retinyl acetate, Retinoic acid and 13-cis Retinoic acid and vitamin D directly inhibit mycobacterial growth in culture. These data are compatible with the hypothesis that complementing the immune response of multicellular organisms, vitamins A and D may have heretofore unproven, unrecognized, independent and probable synergistic, direct antimycobacterial inhibitory activity.