TLR ligands that stimulate the metabolism of vitamin D3 in activated murine dendritic cells can function as effective mucosal adjuvants to subcutaneously administered vaccines. Vaccine. 2008;26:601-613. [PMID: 18178294 DOI: 10.1016/j.vaccine.2007.11.084]

Association between Vitamin D Deficiency and Serologic Response to Hepatitis B Virus Vaccination among Heavy Industry Workers

INTRODUCTION

Hepatitis B virus (HBV) vaccination has decreased the overall incidence of HBV infection; however, approximately 5 to 10% of people are non-responders to the vaccination. This study investigated the factors associated with non-response to HBV vaccination, with an emphasis on vitamin D deficiency (VDD).

METHODS

This retrospective observational study focused on adult workers in a single heavy industry. Individuals with negative initial hepatitis B surface antibody (anti-HBs) levels prior to vaccination and who then received a two- or three-dose series of HBV vaccinations were enrolled. The study endpoint was failure to achieve a seroprotective antibody response, defined as an anti-HBs titer less than 10 mIU/mL. Propensity score matching (PSM) and binary logistic regression models were used to adjust the outcomes for other clinical characteristics.

RESULTS

Among 760 workers, 566 (74.5%) exhibited VDD. The non-response rates to HBV vaccination were 13.4% (76/566) and 5.7% (11/194) among workers with and without VDD, respectively (p = 0.005). Even after adjustment using PSM, VDD was still associated with a higher rate of response failure (adjusted odds ratio 2.74; 95% confidence interval 1.40-5.38, p = 0.003). The binary logistic regression model showed that VDD, older age, omission of the third vaccine dose, lower initial anti-HBs titer, and current smoking were associated with response failure.

CONCLUSIONS

Our study suggests that VDD may impair the serologic response following HBV vaccination. Further research is needed to evaluate the effectiveness of vitamin D supplementation in increasing the response to HBV vaccination.

Lack of relationship between 25-hydoxyvitamin D concentration and a titer of antibodies to hepatitis B surface antigen in children under 12 years of age

The effect of vitamin D levels on the response to the hepatitis B vaccine in childhood and the induced levels of antibodies against the hepatitis B surface antigen (anti-HBs) is not yet well understood. The study aimed to investigate the relationship between age, serum 25-hydroxyvitamin D (25(OH)D) concentration and anti-HBs titer among children under 12 years old. Serum 25(OH)D concentration and anti-HBs titer were determined in 352 healthy Caucasian children with the average age of 4.2 (2.5; 6.3) years. All children were vaccinated with 3 doses of hepatitis B vaccine (Engerix-B, GlaxoSmithKline Pharmaceuticals Limited) in infancy according to the Centers for Disease Control and Prevention recommendations. Only 14.5% of children had an optimal concentration of 25(OH)D ≥ 30 ng/mL and 71.9% children had a seroprotective anti-HBs titer ≥ 10 mIU/mL. Significant negative correlations were found between 25(OH)D, anti-HBs titer and age (r = –0.420, p = 0.000; r = –0.425, p = 0.000, respectively), and a weak positive correlation between 25(OH)D concentration and anti-HBs titer (r = 0.243, p = 0.000). Analysis of six clusters of children demonstrated that age is the main factor affecting anti-HBs titer. One third of children under 12 years of age had nonprotective anti-HBs titer < 10 mIU/mL and around 40% had vitamin D deficiency. We conclude that vitamin D status has no impact on anti-HBs titer in children vaccinated against hepatitis B virus in infancy. Age, so time since the receipt of the last dose of hepatitis B vaccine, is the main factor influencing a decline in anti-HBs titer.

SARS-CoV-2 spike protein antibody titers 6 months after SARS-CoV-2 mRNA vaccination among patients undergoing hemodialysis in Japan

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is shown to prevent severe illness and death in hemodialysis (HD) patients, but the immune response to vaccines is reduced in this population. This study compared SARS-CoV-2 spike protein antibody titers between HD patients and healthy controls in Japan for up to 6 months following vaccination.

METHODS

A multi-institutional retrospective study at five clinics in Japan was conducted using 412 HD patients and 156 healthy controls who received two doses of the BNT162b2 (Pfizer-BioNTech) mRNA vaccine. Anti-SARS-CoV-2 spike protein S1 IgG antibody titers were measured at 1, 3, and 6 months after the second dose. The attenuation speed was calculated as slope (i.e., -β) using a linear mixed-effects model toward the log-transformed antibody titers.

RESULTS

The HD group had significantly lower month 1 antibody titers (Ab-titer-1) than the controls, and these remained lower through month 6 (95% CI: 2617.1 (1296.7, 5240.8) vs. 7285.4 (4403.9, 11,000.0) AU/mL at Ab-titer-1, and 353.4 (178.4, 656.3) vs. 812.0 (498.3, 1342.7) AU/mL at Ab-titer-6 (p < 0.001, respectively)). Lower log Ab-titer-1 levels in the HD group were significantly associated with a lower log Ab-titer-6 (0.90 [0.83, 0.97], p < 0.001). The -β values in the HD patients and healthy controls were -4.7 ± 1.1 and -4.7 ± 1.4 (year-1), respectively.

CONCLUSION

SARS-CoV-2 spike protein antibody titers were significantly lower in HD patients than in healthy controls at 1 (peak) and 6 months after the second vaccination. Low peak antibody titers contributed to low 6-month antibody titers.

Vitamin D: A Potential Mitigation Tool for the Endemic Stage of the COVID-19 Pandemic?

The impact of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and associated development of clinical symptoms of COVID-19 have presented an enormous global impact on our health care systems, public health and economy. To date several observational epidemiological studies consistently found that vitamin D deficiency, measured as low levels of circulating 25-hydroxyvitamin D, is associated with cardiovascular diseases, diabetes, certain cancers, autoimmune diseases and many infectious diseases, including acute respiratory infections. Since vitamin D is not merely immunosuppressive but also acts as an immunomodulator in tolerance and homeostasis, many experts have considered a role of vitamin D in the prevalence and severity of immune mediated inflammatory diseases, such as SARS-CoV-2, adding to the evidence of the importance of vitamin D in the immune response against viral respiratory infections and reinforcing the need for targeted vitamin D supplementation, with a focus on high-risk populations and a high-dose supplementation treatment for COVID-19 hospitalized patients. The expected transition to endemicity of SARS-CoV-2 even further corroborates as a potential of vitamin D as an potential mitigation tool for the prevention of COVID-19. The aim of this paper is to analyse the current evidence regarding vitamin D and present a hypothesis of its potential role in the current COVID-19 pandemic and in the future as a potential preventive measurement in public health.

The Effects of 1,25(OH)2D3 treatment on Immune Responses and Intracellular Metabolic Pathways of Bone Marrow-Derived Dendritic Cells from Lean and Obese Mice

Vitamin D affects differentiation, maturation, and activation of dendritic cells (DCs). Obesity-related immune dysfunction is associated with metabolic changes in immune cells. Objectives of the study are to investigate the effects of vitamin D and obesity on immune responses and markers related to immunometabolism of bone marrow-derived dendritic cells (BMDCs). Bone marrow cells (BMCs) were isolated from lean and obese mice, and BMDCs were generated by culturing BMCs with rmGM-CSF. BMDCs were treated with 1 or 10 nM of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), and maturation was induced by LPS (50 ng/mL) stimulation for 24 h. Cell phenotypes, cytokine productions, and expression of proteins and genes involved in Akt/mTOR signaling pathway and glycolytic pathway were determined. 1,25(OH)2D3 treatment inhibited differentiation of BMDCs (CD11c⁺ %), expression of phenotypes related with DC function (MHC class II and CD86) and production of IL-12p70 in both lean and obese mice. The expression of PD-L1 and the ratio of IL-10/IL-12p70 were increased by 1,25(OH)2D3. With 1,25(OH)2D3 treatment, Akt/mTOR signaling pathway was suppressed, and expression of genes related to glycolysis (Glut1, Pfkfb4, Hif1A) was increased. The upregulation of glycolysis-related genes observed with 1,25(OH)2D3 treatment seems to be associated with the induction of tolerogenic features of BMDCs from lean and obese mice, and Hif1A seems to have a potential role in conveying the effect of 1,25(OH)2D3 on glycolysis. This article is protected by copyright. All rights reserved.

Cholecalciferol supplementation to improve the hepatitis B vaccination response in hemodialysis patients: A first randomized open label pilot study (DeVitaHep)

BACKGROUND

Patients with advanced chronic kidney disease should be vaccinated against hepatitis B. In observational studies vitamin D insufficiency is associated with a reduced seroconversion rate. The effect of cholecalciferol supplementation on hepatitis B vaccination response in haemodialysis patients with vitamin D insufficiency is unknown.

METHODS

In this randomized open label pilot study 40 unvaccinated haemodialysis patients with 25(OH)D insufficiency (<30 ng/mL) were enrolled. In the supplementation group, we administered cholecalciferol orally in a dose of 28,000 IU weekly for a maximum of 12 weeks. Hepatitis B vaccination (HBvaxPRO 40 µg i.m. months 0, 1, 6) was performed after achieving a 25(OH)D level >30 ng/mL or after completing three months of supplementation despite failure to achieve the target level. In the control group, patients were vaccinated immediately after randomization. Anti-hepatitis B-antibody titer (anti-HBs) was measured eight weeks after completing the vaccination course.

RESULTS

Thirty-seven (26 male, 11 female) patients aged 65 (13.5) years underwent randomization with 17 patients allocated to the control group and 20 patients included in the supplementation group. After 12 weeks of cholecalciferol supplementation, mean (SD) 25(OH)D concentration increased from 15.0 (8.0) to 31.0 (7.1) ng/mL, but remained unchanged in the control group (14.0 (7.1) to 11.6 (7.5) mg/mL). Neither the number of patients with seroconversion (anti-HBs titer ≥ 10 IU/L; n = 6 (35.3%) vs n = 3 (27.3%), p = 0.704), nor the number of patients with seroprotection (anti-HBs titer >100 IU/L; n = 4 (23.5%) vs n = 2 (18.2%) differed between treatment groups. Cholecalciferol supplementation was safe without treatment-related adverse events.

CONCLUSION

In this small pilot study, high-dose oral cholecalciferol supplementation did not improve the hepatitis B vaccination response in haemodialysis patients with vitamin D insufficiency. This clinical trial was registered within EudraCT (EudraCT number 2011-004621-26).

The Safety and Immunogenicity of the mRNA-BNT162b2 SARS-CoV-2 Vaccine in Hemodialysis Patients

Background

Hemodialysis patients are at high risk for severe COVID-19. SARS-CoV-2 vaccination related safety and immunogenicity data in these patients are rare.

Methods

In this observational study SARS-CoV-2-seronegative hemodialysis patients were vaccinated with two doses of the Pfizer/BioNTech mRNA-BNT162b2 vaccine (COMIRNATY^® 30 µg) and followed for 90 days. Local and systemic side effects were assessed at every dialysis session during the first post-vaccination week after the first and second vaccine dose. Immunogenicity was determined four weeks after vaccination by quantifying anti-SARS-CoV-2 spike protein IgG antibodies (LIAISON^® SARS-CoV-2-TrimericS IgG chemiluminescent immunoassay) expressed in binding activity units per milliliter (BAU/mL) adapted to the WHO International standard.

Results

Fifty patients (32% women, 68% men) with a mean (SD) age of 67.6 (14.8) years were included. Mild local reactions occurred in 38% after the first injection, and in 29.2% with mild, in 2.1% with moderate and in 2.1% with severe degree after the second injection. Systemic reactive events occurred less often, with diarrhea (4% mild, 4% moderate) and fatigue (8% mild) being the most frequent ones. After the first injection 42% of the patients developed a positive response using the assay specific cut-off value of 33.8 binding activity units per milliliter (BAU/mL) with a median (Q1, Q3) anti-SARS-CoV-2 spike IgG concentration of 20.0 (11.7, 51.0) BAU/mL. After the second injection the percentage of seropositive patients increased to 97.9% with an anti-SARS-CoV-2 spike IgG concentration of 1075 (290.8, 1735) BAU/mL. Higher age and immunosuppression were associated with lower, calcitriol treatment and prior seroconversion to hepatitis B vaccination with significantly higher antibody concentration.

Conclusions

The mRNA-BNT162b2 SARS-CoV-2 vaccine appears to be safe and well-tolerated and shows a high immunogenicity in hemodialysis patients.

Vitamin D, zinc and glutamine: Synergistic action with OncoTherad immunomodulator in interferon signaling and COVID‑19 (Review)

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was identified in December, 2019 in Wuhan, China. Since then, it has continued to spread rapidly in numerous countries, while the search for effective therapeutic options persists. Coronaviruses, including SARS-CoV-2, are known to suppress and evade the antiviral responses of the host organism mediated by interferon (IFN), a family of cytokines that plays an important role in antiviral defenses associated with innate immunity, and has been used therapeutically for chronic viral diseases and cancer. On the other hand, OncoTherad, a safe and effective immunotherapeutic agent in the treatment of non-muscle invasive bladder cancer (NMIBC), increases IFN signaling and has been shown to be a promising therapeutic approach for COVID-19 in a case report that described the rapid recovery of a 78-year-old patient with NMIBC with comorbidities. The present review discusses the possible synergistic action of OncoTherad with vitamin D, zinc and glutamine, nutrients that have been shown to facilitate immune responses mediated by IFN signaling, as well as the potential of this combination as a therapeutic option for COVID-19.

Synergy of melanin and vitamin-D may play a fundamental role in preventing SARS-CoV-2 infections and halt COVID-19 by inactivating furin protease

Since the birth of Christ, in these 2019 years, the man on earth has never experienced a survival challenge from any acellular protist compared to SARS-CoV-2. No specific drugs yet been approved. The host immunity is the only alternative to prevent and or reduce the infection and mortality rate as well. Here, a novel mechanism of melanin mediated host immunity is proposed having potent biotechnological prospects in health care management of COVID-19. Vitamin D is known to enhance the rate of melanin synthesis; and this may concurrently regulate the expression of furin expression. In silico analyses have revealed that the intermediates of melanin are capable of binding strongly with the active site of furin protease. On the other hand, furin expression is negatively regulated via 1-α-hydroxylase (CYP27B1), that belongs to vitamin-D pathway and controls cellular calcium levels. Here, we have envisaged the availability of biological melanin and elucidated the bio-medical potential. Thus, we propose a possible synergistic application of melanin and the enzyme CYP27B1 (regulates vitamin D biosynthesis) as a novel strategy to prevent viral entry through the inactivation of furin protease and aid in boosting our immunity at the cellular and humoral levels.

The Role of Micronutrients in Support of the Immune Response against Viral Infections

Viral infections are a leading cause of morbidity and mortality worldwide, and the importance of public health practices including handwashing and vaccinations in reducing their spread is well established. Furthermore, it is well known that proper nutrition can help support optimal immune function, reducing the impact of infections. Several vitamins and trace elements play an important role in supporting the cells of the immune system, thus increasing the resistance to infections. Other nutrients, such as omega-3 fatty acids, help sustain optimal function of the immune system. The main aim of this manuscript is to discuss of the potential role of micronutrients supplementation in supporting immunity, particularly against respiratory virus infections. Literature analysis showed that in vitro and observational studies, and clinical trials, highlight the important role of vitamins A, C, and D, omega-3 fatty acids, and zinc in modulating the immune response. Supplementation with vitamins, omega 3 fatty acids and zinc appears to be a safe and low-cost way to support optimal function of the immune system, with the potential to reduce the risk and consequences of infection, including viral respiratory infections. Supplementation should be in addition to a healthy diet and fall within recommended upper safety limits set by scientific expert bodies. Therefore, implementing an optimal nutrition, with micronutrients and omega-3 fatty acids supplementation, might be a cost-effective, underestimated strategy to help reduce the burden of infectious diseases worldwide, including coronavirus disease 2019 (COVID-19).

The effects of 1,25-dihydroxyvitamin D3 on markers related to the differentiation and maturation of bone marrow-derived dendritic cells from control and obese mice

Vitamin D has been reported to regulate the maturation and function of dendritic cells (DCs). Obesity was shown to be associated with the dysregulation of vitamin D metabolism and malfunction of DCs. We investigated the effects of in vitro 1,25(OH)₂D₃ treatment (0, 1, or 10 nM) on phenotype and expression of genes related to function of bone marrow-derived DCs (BMDCs) from control and obese mice. C57BL/6 N mice were fed a control or high-fat (10% or 45% kcal fat: CON or HFD) diets for 15 weeks. Differentiation toward DCs was induced with GM-CSF (20 ng/ml) and maturation was induced by LPS (50 ng/ml); 10 nM 1,25(OH)₂D₃ treatment inhibited BMDC differentiation (CD11c⁺) and decreased the percentage of mature DCs (MHCII^highCD11c⁺ and CD86^highCD11c⁺) in both CON and HFD groups. The Il10 expression in stimulated BMDCs from the CON group increased with the 10 nM 1,25(OH)₂D₃ treatment, but not in those from the HFD group. The Il12b mRNA levels in stimulated BMDCs were lower in the HFD group than in the CON group. In conclusion, lower levels of Cd 40, Cd83 and Il12 mRNA in LPS-stimulated BMDCs from obese mice suggest malfunction of DCs as antigen presenting cells. 1,25(OH)₂D₃ treatment inhibited the differentiation and maturation of BMDCs in both control and obese mice. Differential effects of 1,25(OH)₂D₃ on the expression of Il10 between control and obese mice suggest that regulation of immune response by vitamin D could be influenced by obesity.

The potential for vaccines against scour worms of small ruminants

This review addresses the research landscape regarding vaccines against scour worms, particularly Trichostrongylus spp. and Teladorsagia circumcincta. The inability of past research to deliver scour-worm vaccines with reliable and reproducible efficacy has been due in part to gaps in knowledge concerning: (i) host-parasite interactions leading to development of type-2 immunity, (ii) definition of an optimal suite of parasite antigens, and (iii) rational formulation and administration to induce protective immunity against gastrointestinal nematodes (GIN) at the site of infestation. Recent 'omics' developments enable more systematic analyses. GIN genomes are reaching completion, facilitating "reverse vaccinology" approaches that have been used successfully for the Rhipicephalus australis vaccine for cattle tick, while methods for gene silencing and editing in GIN enable identification and validation of potential vaccine antigens. We envisage that any efficacious scour worm vaccine(s) would be adopted similarly to "Barbervax™" within integrated parasite management schemes. Vaccines would therefore effectively parallel the use of resistant animals, and reduce the frequency of drenching and pasture contamination. These aspects of integration, efficacy and operation require updated models and validation in the field. The conclusion of this review outlines an approach to facilitate an integrated research program.

Vitamin D and the hepatitis B vaccine response: a prospective cohort study and a randomized, placebo-controlled oral vitamin D3 and simulated sunlight supplementation trial in healthy adults

Purpose

To determine serum 25(OH)D and 1,25(OH)₂D relationship with hepatitis B vaccination (study 1). Then, to investigate the effects on hepatitis B vaccination of achieving vitamin D sufficiency (serum 25(OH)D ≥ 50 nmol/L) by a unique comparison of simulated sunlight and oral vitamin D₃ supplementation in wintertime (study 2).

Methods

Study 1 involved 447 adults. In study 2, 3 days after the initial hepatitis B vaccination, 119 men received either placebo, simulated sunlight (1.3 × standard-erythema dose, 3 × /week for 4 weeks and then 1 × /week for 8 weeks) or oral vitamin D₃ (1000 IU/day for 4 weeks and 400 IU/day for 8 weeks). We measured hepatitis B vaccination efficacy as percentage of responders with anti-hepatitis B surface antigen immunoglobulin G ≥ 10 mIU/mL.

Results

In study 1, vaccine response was poorer in persons with low vitamin D status (25(OH)D ≤ 40 vs 41–71 nmol/L mean difference [95% confidence interval] − 15% [− 26, − 3%]; 1,25(OH)₂D ≤ 120 vs ≥ 157 pmol/L − 12% [− 24%, − 1%]). Vaccine response was also poorer in winter than summer (− 18% [− 31%, − 3%]), when serum 25(OH)D and 1,25(OH)₂D were at seasonal nadirs, and 81% of persons had serum 25(OH)D < 50 nmol/L. In study 2, vitamin D supplementation strategies were similarly effective in achieving vitamin D sufficiency from the winter vitamin D nadir in almost all (~ 95%); however, the supplementation beginning 3 days after the initial vaccination did not effect the vaccine response (vitamin D vs placebo 4% [− 21%, 14%]).

Conclusion

Low vitamin D status at initial vaccination was associated with poorer hepatitis B vaccine response (study 1); however, vitamin D supplementation commencing 3 days after vaccination (study 2) did not influence the vaccination response.

Clinical trial registry number

Study 1 NCT02416895; https://clinicaltrials.gov/ct2/show/study/NCT02416895; Study 2 NCT03132103; https://clinicaltrials.gov/ct2/show/NCT03132103.

Electronic supplementary material

The online version of this article (10.1007/s00394-020-02261-w) contains supplementary material, which is available to authorized users.

Repurposing the psoriasis drug Oxarol to an ointment adjuvant for the influenza vaccine

Aluminum precipitates have long been used as adjuvants for human vaccines, but there is a clear need for safer and more effective adjuvants. Here we report in a mouse model that the psoriasis drug Oxarol ointment is a highly effective vaccine adjuvant. By applying Oxarol ointment onto skin, humoral responses and germinal center (GC) reactions were augmented, and the treated mice were protected from death caused by influenza virus infection. Keratinocyte-specific vitamin D3 receptor (Vdr) gene expression was required for these responses through induction of the thymic stromal lymphopoietin (Tslp) gene. Experiments involving administration of recombinant TSLP or, conversely, anti-TSLP antibody demonstrated that TSLP plays a key role in the GC reactions. Furthermore, cell-type-specific Tslpr gene deletion or diphtheria toxin-mediated deletion of specific cell types revealed that CD11c+ cells excluding Langerhans cells were responsible for the Oxarol-mediated GC reactions. These results indicate that active vitamin D3 is able to enhance the humoral response via Tslp induction in the skin and serves as a new vaccine adjuvant.

Vitamin D and toll like receptors

It has been demonstrated that vitamin D (VD) significantly modulates immune responses. Toll like receptors (TLRs) are the main innate immunity receptors which are expressed on the cell membrane and intracellular vesicles and recognize several pathogen associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs) to induce immune responses. Based on the important roles played by TLRs in physiologic and pathologic functions of immune responses and due to the immunomodulatory functions of VD, it has been hypothesized that VD may present its immunomodulatory functions via modulation of TLRs. This review article collates recent studies regarding the interactions between VD and TLRs and discussed the controversial investigations.

Vitamin D deficiency in children with recurrent respiratory infections, with or without immunoglobulin deficiency

PURPOSE

The objective of this study was to evaluate thevitamin D concentration in patients with recurrent respiratory infections with or without immunoglobulin G, A or M (IgG, IgA, IgM) deficiency, and to find a correlation between the vitamin D concentration and the response to hepatitis B vaccination.

MATERIALS AND METHOD

The study involved 730 patients with recurrent respiratory infections. The concentration of 25-hydroxyvitamin D (25(OH)D), immunoglobulins G, A and M, anti-HBs was determined.

RESULTS

The tests showed that 11% of patients presented IgG levels below the age related reference values. Children with reduced IgG concentration were also found to have significantly lower vitamin D concentrations in comparison to children with normal IgG. Vitamin D deficiency was observed in schoolchildren between 7 and 18 years of age. No correlation was found between 25(OH)D concentration and Hbs antibody levels.

CONCLUSIONS

An investigation of a large group of patients who have recurrent infection found patients with IgG deficiency to whom special proceeding have to be performed: 1. Significantly lower vitamin D concentration observed in the group of children with IgG deficiency implicated in long-lasting monitoring of vitamin D level require adding to the practice guidelines for Central Europe 2013. 2. Intervention treatment with suitable doses of vitamin D to clarified metabolism of vitamin D has to be plan for children with IgG deficiency and significant lower vitamin D concentration.

Parenterally Administered Norovirus GII.4 Virus-Like Particle Vaccine Formulated with Aluminum Hydroxide or Monophosphoryl Lipid A Adjuvants Induces Systemic but Not Mucosal Immune Responses in Mice

Norovirus (NoV) is a main cause of acute gastroenteritis across all ages worldwide. NoV vaccine candidates currently in clinical trials are based on noninfectious highly immunogenic virus-like particles (VLPs) delivered intramuscularly (IM). Since NoV is an enteric pathogen, it is likely that mucosal immunity has a significant role in protection from infection in the intestine. Due to the fact that IM delivery of NoV VLPs does not generate mucosal immunity, we investigated whether NoV genotype GII.4 VLPs coadministered with aluminum hydroxide (Al(OH)₃) or monophosphoryl lipid A (MPLA) would induce mucosal antibodies in mice. Systemic as well as mucosal IgG and IgA antibodies in serum and intestinal and nasal secretions were measured. As expected, strong serum IgG, IgG1, and IgG2a antibodies as well as a dose sparing effect were induced by both Al(OH)₃ and MPLA, but no mucosal IgA antibodies were detected. In contrast, IN immunization with GII.4 VLPs without an adjuvant induced systemic as well as mucosal IgA antibody response. These results indicate that mucosal delivery of NoV VLPs is needed for induction of mucosal responses.

Vitamin D immunoregulation through dendritic cells

Vitamin D (VD3) has been linked to immunological processes, and its supplementation may have a role in treatment or prevention of diseases with underlying autoimmune or pro‐inflammatory states. As initiators of the immune responses, dendritic cells (DC) are a potential target of VD3 to dampen autoimmunity and inflammation, but the role of DC in VD3‐mediated immunomodulation in vivo is not understood. In addition to being targets of VD3, DC can provide a local source of bioactive VD3 for regulation of T‐cell responses. Here we review existing studies that describe the tolerogenic potential of VD3 on DC, and discuss them in the context of current understanding of DC development and function. We speculate on mechanisms that might account for the potent but poorly understood tolerogenic activities of VD3 and the role of DC as both targets and sources of this hormone.

Parenteral Vaccination Can Be an Effective Means of Inducing Protective Mucosal Responses

The current paradigm in vaccine development is that nonreplicating vaccines delivered parenterally fail to induce immune responses in mucosal tissues. However, both clinical and experimental data have challenged this concept, and numerous studies have shown that induction of mucosal immune responses after parenteral vaccination is not a rare occurrence and might, in fact, significantly contribute to the protection against mucosal infections afforded by parenteral vaccines. While the mechanisms underlying this phenomenon are not well understood, the realization that parenteral vaccination can be an effective means of inducing protective mucosal responses is paradigm-shifting and has potential to transform the way vaccines are designed and delivered.

Regulation of Dendritic Cell Function by Vitamin D

Studies over the last two decades have revealed profound immunomodulatory aspects of vitamin D on various aspects of the immune system. This review will provide an overview of Vitamin D metabolism, a description of dendritic cell subsets, and highlight recent advances on the effects of vitamin D on dendritic cell function, maturation, cytokine production and antigen presentation. The active form of vitamin D, 1,25(OH)₂D₃, has important immunoregulatory and anti-inflammatory effects. Specifically, the 1,25(OH)₂D₃-Vitamin D₃ complex can affect the maturation and migration of many dendritic cell subsets, conferring a special immunoregulatory role as well as tolerogenic properties affecting cytokine and chemokine production. Furthermore, there have been many recent studies demonstrating the effects of Vitamin D on allergic disease and autoimmunity. A clear understanding of the effects of the various forms of Vitamin D will provide new opportunities to improve human health.

Modulation of the immune response to respiratory viruses by vitamin D

Background: Vitamin D deficiency has been shown to be independently associated with increased risk of viral acute respiratory infection (ARI) in a number of observational studies, and meta-analysis of clinical trials of vitamin D supplementation for prevention of ARI has demonstrated protective effects. Several cellular studies have investigated the effects of vitamin D metabolites on immune responses to respiratory viruses, but syntheses of these reports are lacking. Scope: In this article, we review the literature reporting results of in vitro experiments investigating immunomodulatory actions of vitamin D metabolites in human respiratory epithelial cells infected with respiratory viruses. Key findings: Vitamin D metabolites do not consistently influence replication or clearance of rhinovirus, respiratory syncytial virus (RSV) or influenza A virus in human respiratory epithelial cell culture, although they do modulate expression and secretion of type 1 interferon, chemokines including CXCL8 and CXCL10 and pro-inflammatory cytokines, such as TNF and IL-6. Future research: More studies are needed to clarify the effects of vitamin D metabolites on respiratory virus-induced expression of cell surface markers mediating viral entry and bacterial adhesion to respiratory epithelial cells.

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.

Does vitamin D protect against respiratory viral infections?

The active form of vitamin D has effects on both innate and adaptive immune responses that may influence the outcome in many infectious diseases. Observational studies conclusively show that a low vitamin D status is associated with an increased occurrence of respiratory viral infections, which globally represent significant health and financial burdens. However, no consistent protective effects are evident in prospective clinical trials carried out to date where vitamin D was provided as a dietary supplement, except possibly in cases where the starting vitamin D status of the individual was considered deficient. Thus far, vitamin D has not been found to enhance the immune response to vaccines. The design of future prospective clinical trials assessing a role for vitamin D in respiratory viral infections requires very careful planning to avoid the uncertainties associated with the data available currently.

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.

Effects of vitamin D on antigen-specific and non-antigen-specific immune modulation: relevance for type 1 diabetes

Vitamin D is a fat-soluble precursor of the circulating 25-hydroxyvitamin D₃ (25(OH)D₃)which can be converted by the 1α-hydroxylase (1α(OH)ase) enzyme into the bioactive hormonal metabolite 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), generally known to promote bone mineralization through its ability to enhance calcium absorption from the gut. Importantly, in humans, vitamin D is mainly derived from endogenous production of vitamin D₃ from ultraviolet (UV) radiation exposure to the skin while a small part (<10%) is obtained via dietary intake of dairy products and fatty fish (1). Taking these factors into account, geographic distribution and seasonality, skin pigmentation, age, and lifestyle may predispose certain populations to be at a higher risk of developing vitamin D insufficiency or deficiency (2). The first valid reports correlating the importance of an adequate vitamin D status to optimal human health originate from the early part of the 20th century, when vitamin D was described to prevent and treat the bone disease rickets. Since then, the findings that vitamin D receptors (VDR) are present in many body tissues and that vitamin D metabolizing enzymes can be found in various cells outside the kidney, including the intestine, prostate, immune cells, and within the skin itself (reviewed in reference 3), have revolutionized the vitamin D business. In this review, we will mainly focus on vitamin D as a component of immune regulation and on the role of vitamin D in antigen-specific and non-specific therapies with potential relevance for type 1 diabetes (T1D).

Impact of vitamin D administration on immunogenicity of trivalent inactivated influenza vaccine in previously unvaccinated children

As vitamin D (VD) has a significant regulatory effect on innate and adaptive immunity, the aim of this prospective, randomized, single-blinded, placebo-controlled study was to measure the impact of VD administration on the immune response to trivalent influenza vaccination (TIV). A total of 116 children (61 males, 52.6%; mean age 3.0 ± 1.0 y) with a history of recurrent acute otitis media (AOM), who had not been previously vaccinated against influenza, were randomized to receive daily VD 1,000 IU or placebo by mouth for four months. All of them received two doses of TIV (Fluarix, GlaxoSmithKline Biologicals) one month apart, with the first dose administered when VD supplementation was started. There was no difference in seroconversion or seroprotection rates, or antibody titers, in relation to any of the three influenza vaccine antigens between the VD and placebo groups, independently of baseline and post-treatment VD levels. The safety profile was also similar in the two groups. These data indicate that the daily administration of VD 1,000 IU for four months from the time of the injection of the first dose of TIV does not significantly modify the antibody response evoked by influenza vaccine.

A vitamin D3 analog augmented interleukin-8 production by human monocytic cells in response to various microbe-related synthetic ligands, especially NOD2 agonistic muramyldipeptide

Active metabolite vitamin D(3), 1α,25-dihydroxyvitamin D(3), is a pleiotropic factor and exhibits various physiological functions, including immunomodulating activities. In this study, the possible regulation of innate immune responses of human monocytic cells by a vitamin D(3) analog was examined. Human monocytic THP-1 cells were pre-treated with OCT, vitamin D(3) analog, 1α,25-dihydroxy-22-oxavitamin D(3), followed by stimulation with various chemically synthesized Toll-like receptors (TLR) and NOD1 and NOD2 ligands. OCT-treated cells produced more IL-8 than non-treated cells upon stimulation with various chemically-synthesized ligands: TLR2-agonistic lipopeptide (FSL-1), TLR3-agonistic poly I:C, TLR4-agonistic lipid A (E. coli-type LA-15-PP), NOD1-agonistic FK565 and NOD2-agonistic muramyldipeptide (MDP). Among the ligands, MDP was the highest inducer of IL-8 production in OCT-treated THP-1 cells, and IL-8 production increased depending on the treatment time until 72h. OCT up-regulated the expression of NOD2 in THP-1 cells, and OCT-treated cells exhibited higher activation of p38, JNK and ERK in the MAPK pathway, IκBα in the NF-κB pathway, and TAK1 upstream in response to MDP than non-treated cells. Analysis using siRNA against NOD2 and inhibitors of specific signal molecules indicated that the existence of NOD2 and activation of the above signaling molecules are required for enhanced production of IL-8 in OCT-treated THP-1 cells. These findings suggested that NOD2, NF-κB and MAPK pathways are involved in the activity of OCT to augment the response of human monocytic cells to MDP.

Therapeutic DNA vaccine induces broad T cell responses in the gut and sustained protection from viral rebound and AIDS in SIV-infected rhesus macaques

Immunotherapies that induce durable immune control of chronic HIV infection may eliminate the need for life-long dependence on drugs. We investigated a DNA vaccine formulated with a novel genetic adjuvant that stimulates immune responses in the blood and gut for the ability to improve therapy in rhesus macaques chronically infected with SIV. Using the SIV-macaque model for AIDS, we show that epidermal co-delivery of plasmids expressing SIV Gag, RT, Nef and Env, and the mucosal adjuvant, heat-labile E. coli enterotoxin (LT), during antiretroviral therapy (ART) induced a substantial 2-4-log fold reduction in mean virus burden in both the gut and blood when compared to unvaccinated controls and provided durable protection from viral rebound and disease progression after the drug was discontinued. This effect was associated with significant increases in IFN-γ T cell responses in both the blood and gut and SIV-specific CD8+ T cells with dual TNF-α and cytolytic effector functions in the blood. Importantly, a broader specificity in the T cell response seen in the gut, but not the blood, significantly correlated with a reduction in virus production in mucosal tissues and a lower virus burden in plasma. We conclude that immunizing with vaccines that induce immune responses in mucosal gut tissue could reduce residual viral reservoirs during drug therapy and improve long-term treatment of HIV infection in humans.

Vitamin D deficiency is associated with poor response to active hepatitis B immunisation in patients with chronic kidney disease

Vitamin D deficiency is highly prevalent in patients suffering from chronic kidney disease. At present it is not known whether this condition is associated with poor response to hepatitis B vaccination in these patients. We performed a retrospective analysis of 200 patients with chronic kidney disease stages 3-5D, who had undergone hepatitis B vaccination with three 40 μg recombinant hepatitis B vaccine doses in a single centre. Anti-HBs antibody titres and 25-hydroxyvitamin D (25(OH)D) levels were measured by chemiluminescence immunoassays. Vitamin D deficiency with serum levels <10 ng/mL was found in 35.5% of patients. These patients had a lower seroconversion rate than did patients with levels ≥10 ng/mL (45% vs 64%; P=0.011) and their median (25th, 75th percentile) anti-HBs antibody titres were lower (0 (0, 117)IU/L vs 48 (0, 236.5)IU/L). Non-responders had lower 25(OH)D concentrations than did responders (12.9±6.5 ng/mL vs 15.1±7.4 ng/mL; P=0.034). Treatment with a vitamin D receptor activator had no influence on the immune response. In a multiple logistic regression analysis vitamin D deficiency (OR 0.480; P=0.023) and diabetes (OR 0.496; P=0.038) remained independent and significant negative predictors of seroconversion. In conclusion, in patients with chronic kidney disease vitamin D deficiency is associated with a poor antibody formation upon hepatitis B vaccination.

TLR2-dependent modulation of dendritic cells by LT-IIa-B5, a novel mucosal adjuvant derived from a type II heat-labile enterotoxin

A host of human pathogens invades the body at mucosal surfaces. Yet, strong, protective mucosal immune responses directed against those pathogens routinely cannot be induced without the use of adjuvants. Although the strongest mucosal adjuvants are members of the family of HLTs, the inherent toxicities of HLT holotoxins preclude their clinical use. Herein, it is shown that LT-IIa-B(5) enhances mucosal immune responses by modulating activities of DCs. i.n. immunization of mice with OVA in the presence of LT-IIa-B(5) recruited DCs to the NALT and significantly increased uptake of OVA by those DCs. Furthermore, LT-IIa-B(5) increased expression of CCR7 by DCs, which mediated enhanced migration of the cells from the NALT to the draining CLNs. LT-IIa-B(5) also enhanced maturation of DCs, as revealed by increased surface expression of CD40, CD80, and CD86. Ag-specific CD4(+) T cell proliferation was augmented in the CLNs of mice that had received i.n. LT-IIa-B(5). Finally, when used as an i.n. adjuvant, LT-IIa-B(5) dramatically increased the levels of OVA-specific salivary IgA and OVA-specific serum IgG. Strikingly, each of the activities induced by LT-IIa-B(5) was strictly TLR2-dependent. The data strongly suggest that the immunomodulatory properties of LT-IIa-B(5) depend on the productive modulation of mucosal DCs. Notably, this is the first report for any HLT to demonstrate in vivo the elicitation of strong, TLR2-dependent modulatory effects on DCs with respect to adjuvanticity.

Distribution of primed T cells and antigen-loaded antigen presenting cells following intranasal immunization in mice

Priming of T cells is a key event in vaccination, since it bears a decisive influence on the type and magnitude of the immune response. T-cell priming after mucosal immunization via the nasal route was studied by investigating the distribution of antigen-loaded antigen presenting cells (APCs) and primed antigen-specific T cells. Nasal immunization studies were conducted using the model protein antigen ovalbumin (OVA) plus CpG oligodeoxynucleotide adjuvant. Trafficking of antigen-specific primed T cells was analyzed in vivo after adoptive transfer of OVA-specific transgenic T cells in the presence or absence of fingolimod, a drug that causes lymphocytes sequestration within lymph nodes. Antigen-loaded APCs were observed in mediastinal lymph nodes, draining the respiratory tract, but not in distal lymph nodes. Antigen-specific proliferating T cells were first observed within draining lymph nodes, and later in distal iliac and mesenteric lymph nodes and in the spleen. The presence at distal sites was due to migration of locally primed T cells as shown by fingolimod treatment that caused a drastic reduction of proliferated T cells in non-draining lymph nodes and an accumulation of extensively divided T cells within draining lymph nodes. Homing of nasally primed T cells in distal iliac lymph nodes was CD62L-dependent, while entry into mesenteric lymph nodes depended on both CD62L and α4β7, as shown by in vivo antibody-mediated inhibition of T-cell trafficking. These data, elucidating the trafficking of antigen-specific primed T cells to non-draining peripheral and mucosa-associated lymph nodes following nasal immunization, provide relevant insights for the design of vaccination strategies based on mucosal priming.

Efficient tetanus toxoid immunization on vitamin D supplementation

BACKGROUND/OBJECTIVES

Vitamin D mediates immunomodulatory functions, and its deficiency has been associated with an increased prevalence of immunological diseases. The supplementation of vitamin D might be therapeutically beneficial, for example, in lupus erythematosus patients. However, its affect on established recall immune responses is undefined.

SUBJECTS/METHODS

In all, 32 individuals were randomized in a placebo controlled, double-blind setting, and received vitamin D (daily 2000 IU) for 10 weeks followed by tetanus toxoid (TT) booster immunization.

RESULTS

During vitamin D supplementation the median 25-hydroxyvitamin D serum concentration increased to 80.3 nM, which as expected decreased in the placebo group to 29.1 nM during the ultraviolet-deprived winter months. The TT-specific immunoglobulin G (IgG) boost efficiency was marginal higher in the vitamin D group (P = 0.04). The increase of the 25-hydroxyvitamin D levels correlated with the increase of TT-IgG serum concentrations. The induction of specific serum IgA and specific antibody secreting cells was comparable between both groups. Accordingly, the TT-specific and polyclonally triggered T-cell cytokine profiles were stable as well.

CONCLUSIONS

Vitamin D supplementation was successful and booster immunization induced efficiently specific antibodies titers.

Delivery of Exogenous Antigens to Induce Cytotoxic CD8+ T Lymphocyte Responses

Vaccines intended to induce a cytotoxic CD8+ T-cell response are highly sought after. However, some of these vaccines can be problematic if they replicate in the host. An alternative strategy is to exploit cross-presentation of exogenous antigens to express peptides on major histocompatibility complex (MHC) class I molecules. During cross-presentation, the delivered exogenous antigen can be taken up and processed through diverse mechanisms. Here, we will discuss the recent advances regarding the complex nature of the cross-priming process and the models that reflect its relevance in vivo. Moreover, we summarize current data that explore potential adjuvants and vaccine vectors that deliver antigens to activate CD8+ T cells relying on cross-presentation.

Human dendritic cell antigen presentation and chemotaxis are inhibited by intrinsic 25-hydroxy vitamin D activation

The immunomodulatory effects of vitamin D have primarily been investigated using the biologically active form 1,25-dihydroxy vitamin D3 (1,25-D3). It was recently demonstrated that dendritic cells (DC) are able to convert the inactive 25-hydroxy vitamin D3 (25-D3) into the active form via 1 alpha-hydroxylase. In this study, we set out to examine the possible consequences of this conversion on adaptive immune functions. Human monocyte-derived DC were matured by lipopolysaccharide (LPS) in the presence or absence of 25-D3. Subsequently, the conversion of 25-D3 into 1,25-D3, and the effects on surface marker expression, cytokine production, antigen-presenting capacity and chemotaxis of the DC were examined. 25-D3 was clearly converted into 1,25-D3 in the DC cultures and the process was accompanied by a reduced expression of CD80 (p<0.01), CD83 (p<0.01), CD86 (p=0.02), and HLA-DR (p=0.02). Also, the levels of the pro-inflammatory cytokines tumour necrosis factor (TNF) alpha (p=0.02) and interleukin (IL) 12 (p<0.01) were reduced. Interestingly, however, the CD14 expression (p<0.01) and the production of IL-1 beta (p<0.01) and IL-6 (p<0.01) increased. Thus, 25-D3 affected the delicate interplay between anti- and pro-inflammatory cytokines produced by the DC. Concurrently, 25-D3 reduced DC capacity to induce proliferation of antigen-specific T cells and DC chemotaxis towards chemokine (CC) ligand 21. This indicates that 25-D3 has a regulating function following intrinsic 1 alpha-hydroxylation, a mechanism that potentially has an immunomodulatory effect in vivo.

Enhanced humoral and cellular immune responses after sublingual immunization against human papillomavirus 16 L1 protein with adjuvants

Needle-free nonparenteral vaccines offer a number of practical advantages, especially in developing countries. To address the effects of vaccine administration route, we tested mucosal and systemic immune responses against human papillomavirus 16 L1(HPV16L1) protein using intranasal, intravaginal, transdermal, sublingual (SL) and intramuscular routes. The SL route provided the most effective mucosal secretory IgA (sIgA) and serum IgG responses. After a 150 microg antigen dose via the SL route, saliva sIgA levels were 7.2- and 5.8-fold higher than those achieved via intravaginal and transdermal routes, respectively. Notably, SL administration even produced 4.6-fold higher levels of vaginal sIgA levels than did intravaginal delivery of 150 microg antigen. To enhance the immunogenicity of SL vaccines, we tested the adjuvanticity of nine molecules: three toll-like receptor agonists, three nucleotide-binding oligomerization-domain agonists, vitamin D3, poly-gamma-glutamic acid and cholera toxin subunit B (CTB). Among the molecules tested, CTB provided the most enhanced mucosal sIgA and systemic IgG induction. SL-applied CTB enhanced the production of interleukin-4 and interferon-gamma from stimulated CD4+ T cells. Moreover, interferon-gamma-producing CD8+ T cell responses were increased 1.7-fold after co-treatment with SL CTB and HPV16L1. These results suggest the potential of the SL route for delivery of HPV16L1 vaccines using CTB as an adjuvant.

Vitamin d and serum cytokines in a randomized clinical trial

Background. The role of vitamin D in the body's ability to fight influenza and URI's may be dependent on regulation of specific cytokines that participate in the host inflammatory response. The aim of this study was to test the hypothesis that vitamin D can influence intracellular signaling to regulate the production of cytokines. Subjects and Methods. This study was a 3-month prospective placebo-controlled trial of vitamin D3 supplementation in ambulatory adults [Li-Ng et al., 2009]. 162 volunteers were randomized to receive either 50 μg/d (2000 IU) of vitamin D3 or matching placebo. 25(OH)D and the levels of 10 different cytokines (IL-2, 4, 5, 6, 8, 10, 13, GM-CSF, IFN-γ, TNF-α) were measured in the serum of participants at baseline and the final visit. There were 6 drop-outs from the active vitamin D group and 8 from the placebo group. Results. In the active vitamin D group, we found a significant median percent decline in levels of GM-CSF (-62.9%, P < .0001), IFN-γ (-38.9%, P < .0001), IL-4 (-50.8%, P = .001), IL-8 (-48.4%, P < .0001), and IL-10 (-70.4%, P < .0001). In the placebo group, there were significant declines for GM-CSF (-53.2%, P = .0007) and IFN-γ (-34.4%, P = .0011). For each cytokine, there was no significant difference in the rate of decline between the two groups. 25(OH)D levels increased in the active vitamin D group from a mean of 64.3 ± 25.4 nmol/L to 88.5 ± 23.2 nmol/L. Conclusions. The present study did not show that vitamin D3 supplementation changed circulating cytokine levels among healthy adults.

Cytokine content in lymphoid and white adipose tissues after repeated CpG oligodeoxynucleotide administration in trained rats

The increased threat of bioterrorism and the emergence of potentially fatal diseases underscores the need to improve treatments for protecting all segments of the human population including military personnel. New methods need to be developed. The ability of oligodeoxynucleotides containing the CpG motif (CpG ODNs) to promote the production of T(H)1-type pro-inflammatory cytokines suggest they might be useful as vaccine adjuvants, but their potential effects during exercise have not been widely studied. Repeated administration of CpG ODN in sedentary rats promoted the production of T(H)1-type pro-inflammatory cytokines in spleen, Peyer's patches and adipose tissues. However, such an increase was not observed in trained rats, suggesting that CpG would not be the best agent for vaccine adjuvants and immunomodulation in intensely trained rats.

Therapeutic targeting of Toll-like receptors for infectious and inflammatory diseases and cancer

Since first being described in the fruit fly Drosophila melanogaster, Toll-like receptors (TLRs) have proven to be of great interest to immunologists and investigators interested in the molecular basis to inflammation. They recognize pathogen-derived factors and also products of inflamed tissue, and trigger signaling pathways that lead to activation of transcription factors such as nuclear factor-kappaB and the interferon regulatory factors. These in turn lead to induction of immune and inflammatory genes, including such important cytokines as tumor necrosis factor-alpha and type I interferon. Much evidence points to a role for TLRs in immune and inflammatory diseases and increasingly in cancer. Examples include clear roles for TLR4 in sepsis, rheumatoid arthritis, ischemia/reperfusion injury, and allergy. TLR2 has been implicated in similar pathologic conditions and also in systemic lupus erythematosus (SLE) and tumor metastasis. TLR7 has also been shown to be important in SLE. TLR5 has been shown to be radioprotective. Recent advances in our understanding of signaling pathways activated by TLRs, structural insights into TLRs bound to their ligands and antagonists, and approaches to inhibit TLRs (including antibodies, peptides, and small molecules) are providing possiblemeans by which to interfere with TLRs clinically. Here we review these recent advances and speculate about whether manipulating TLRs is likely to be successful in fighting off different diseases.

TLR-induced local metabolism of vitamin D3 plays an important role in the diversification of adaptive immune responses

The addition of monophosphoryl lipid A, a minimally toxic derivative of LPS, to nonmucosally administered vaccines induced both systemic and mucosal immune responses to coadministered Ags. This was dependent on an up-regulated expression of 1alpha-hydroxylase (CYP27B1, 1alphaOHase), the enzyme that converts 25-hydroxycholecalciferol, a circulating inactive metabolite of vitamin D(3), into 1,25(OH)2D(3) (calcitriol). In response to locally produced calcitriol, myeloid dendritic cells (DCs) migrated from cutaneous vaccination sites into multiple secondary lymphoid organs, including classical inductive sites of mucosal immunity, where they effectively stimulated B and T cell immune responses. The endogenous production of calcitriol by monophosphoryl lipid A-stimulated DCs appeared to be Toll-IL-1R domain-containing adapter-inducing IFN-beta-dependent, mediated through a type 1 IFN-induced expression of 1alphaOHase. Responsiveness to calcitriol was essential to promote the trafficking of mobilized DCs to nondraining lymphoid organs. Collectively, these studies help to expand our understanding of the physiologically important roles played by locally metabolized vitamin D(3) in the initiation and diversification of adaptive immune responses. The influences of locally produced calcitriol on the migration of activated DCs from sites of vaccination/infection into both draining and nondraining lymphoid organs create a condition whereby Ag-responsive B and T cells residing in multiple lymphoid organs are able to simultaneously engage in the induction of adaptive immune responses to peripherally administered Ags as if they were responding to an infection of peripheral or mucosal tissues they were designed to protect.

Type 1 diabetes, the A1 milk hypothesis and vitamin D deficiency

The 'A1' genetic variant of beta-casein in milk has been linked to type 1 diabetes (T1D). The keystone piece of supporting evidence is an ecological study positively correlating the incidence of T1D with amount of A1 beta-casein consumption per capita. Of relevance, A1 beta-casein consumption is also positively correlated with latitude, itself implicated in T1D through vitamin D deficiency. Ecological and biological evidence convincingly implicate vitamin D deficiency in T1D. Latitude is a confounder of the ecological data that underpin the hypothesis that A1 beta-casein in cow's milk is a causative factor in T1D.

Environmental cues, dendritic cells and the programming of tissue-selective lymphocyte trafficking

Lymphocytes are imprinted during activation with trafficking programs (combinations of adhesion and chemoattractant receptors) that target their migration to specific tissues and microenvironments. Cytokines contribute, but, for gut and skin, evolution has cleverly adapted external cues from food (vitamin A) and sunlight (ultraviolet-induced vitamin D3) to imprint lymphocyte homing to the small intestines and T cell migration into the epidermis. Dendritic cells are essential: they process the vitamins to their active metabolites (retinoic acid and 1,25(OH)(2)D3) for presentation with antigen to lymphocytes, and they help export environmental cues through lymphatics to draining lymph nodes, to program the trafficking and effector functions of naive T and B cells.